175 results on '"Hyun Kyung Chung"'
Search Results
2. Subclinical Hypothyroidism: Prevalence, Health Impact, and Treatment Landscape
- Author
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Won Sang Yoo and Hyun Kyung Chung
- Subjects
subclinical hypothyroidism ,diagnosis ,prevalence ,treatment ,Diseases of the endocrine glands. Clinical endocrinology ,RC648-665 - Abstract
Subclinical hypothyroidism (sHypo) is defined as normal serum free thyroid hormone levels coexisting with elevated serum thyroid-stimulating hormone (TSH) levels. sHypo is a common condition observed in clinical practice with several unique features. Its diagnosis should be based on an understanding of geographic and demographic differences in biochemical criteria versus a global reference range for TSH that is based on the 95% confidence interval of a healthy population. During the differential diagnosis, it is important to remember that a considerable proportion of sHypo cases are transient and reversible in nature; the focus is better placed on persistent or progressive forms, which mainly result from chronic autoimmune thyroiditis. Despite significant evidence documenting the health impacts of sHypo, the effects of levothyroxine treatment (LT4-Tx) in patients with sHypo remains controversial, especially in patients with grade 1 sHypo and older adults. Existing evidence suggests that it is reasonable to refrain from immediate LT4-Tx in most patients if they are closely monitored, except in women who are pregnant or in progressive cases. Future research is needed to further characterize the risks and benefits of LT4-Tx in different patient cohorts.
- Published
- 2021
- Full Text
- View/download PDF
3. Modeling α-Synuclein Propagation with Preformed Fibril Injections
- Author
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Hyun Kyung Chung, Hoang-Anh Ho, Dayana Pérez-Acuña, and Seung-Jae Lee
- Subjects
Neurology. Diseases of the nervous system ,RC346-429 - Published
- 2020
- Full Text
- View/download PDF
4. Modeling α-Synuclein Propagation with Preformed Fibril Injections
- Author
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Hyun Kyung Chung, Hoang-Anh Ho, Dayana Pérez-Acuña, and Seung-Jae Lee
- Subjects
Alpha-synuclein ,Animal models ,Parkinson’s disease ,Protein aggregation ,Neurology. Diseases of the nervous system ,RC346-429 - Abstract
The aggregation of α-synuclein (α-syn) has been implicated in the pathogenesis of many neurodegenerative disorders, including Parkinson’s disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). Postmortem analyses of α-syn pathology, especially that of PD, have suggested that aggregates progressively spread from a few discrete locations to wider brain regions. The neuron-to-neuron propagation of α-syn has been suggested to be the underlying mechanism by which aggregates spread throughout the brain. Many cellular and animal models has been created to study cell-to-cell propagation. Recently, it has been shown that a single injection of preformed fibrils (PFFs) made of recombinant α-syn proteins into various tissues and organs of many different animal species results in widespread α-syn pathology in the central nervous system (CNS). These PFF models have been extensively used to study the mechanism by which aggregates spread throughout the brain. Here, we review what we have learned from PFF models, describe the nature of PFFs and the neuropathological features, neurophysiological characteristics, and behavioral outcomes of the models.
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- 2019
- Full Text
- View/download PDF
5. Recent Advances in Autoimmune Thyroid Diseases
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Won Sang Yoo and Hyun Kyung Chung
- Subjects
Autoimmune thyroid disease ,Graves disease ,Hashimoto disease ,Diseases of the endocrine glands. Clinical endocrinology ,RC648-665 - Abstract
Autoimmune thyroid disease (AITD) includes hyperthyroid Graves disease, hypothyroid autoimmune thyroiditis, and subtle subclinical thyroid dysfunctions. AITD is caused by interactions between genetic and environmental predisposing factors and results in autoimmune deterioration. Data on polymorphisms in the AITD susceptibility genes, related environmental factors, and dysregulation of autoimmune processes have accumulated over time. Over the last decade, there has been progress in the clinical field of AITD with respect to the available diagnostic and therapeutic methods as well as clinical consensus. The updated clinical guidelines allow practitioners to identify the most reasonable and current approaches for proper management. In this review, we focus on recent advances in understanding the genetic and environmental pathogenic mechanisms underlying AITD and introduce the updated set of clinical guidelines for AITD management. We also discuss other aspects of the disease such as management of subclinical thyroid dysfunction, use of levothyroxine plus levotriiodothyronine in the treatment of autoimmune hypothyroidism, risk assessment of long-standing antithyroid drug therapy in recurrent Graves' hyperthyroidism, and future research needs.
- Published
- 2016
- Full Text
- View/download PDF
6. Data on erosion and hydrogen fuel retention in Beryllium plasma-facing materials
- Author
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Gregory De Temmerman, Kalle Heinola, Dmitriy Borodin, Sebastijan Brezinsek, Russell P. Doerner, Marek Rubel, Elżbieta Fortuna-Zaleśna, Christian Linsmeier, Daisuke Nishijima, Kai Nordlund, Michael Probst, Juri Romazanov, Elnaz Safi, Thomas Schwarz-Selinger, Anna Widdowson, Bastiaan J. Braams, Hyun-Kyung Chung, and Christian Hill
- Subjects
Beryllium ,Controlled fusion ,Plasma-facing material ,Erosion–deposition ,Dust ,Nuclear engineering. Atomic power ,TK9001-9401 - Abstract
ITER will use beryllium as a plasma-facing material in the main chamber, covering a total surface area of about 620 m2. Given the importance of beryllium erosion and co-deposition for tritium retention in ITER, significant efforts have been made to understand the behaviour of beryllium under fusion-relevant conditions with high particle and heat loads. This paper provides a comprehensive report on the state of knowledge of beryllium behaviour under fusion-relevant conditions: the erosion mechanisms and their consequences, beryllium migration in JET, fuel retention and dust generation. The paper reviews basic laboratory studies, advanced computer simulations and experience from laboratory plasma experiments in linear simulators of plasma–wall interactions and in controlled fusion devices using beryllium plasma-facing components. A critical assessment of analytical methods and simulation codes used in beryllium studies is given. The overall objective is to review the existing set of data with a broad literature survey and to identify gaps and research needs to broaden the database for ITER.
- Published
- 2021
- Full Text
- View/download PDF
7. Population Kinetics Modeling of Low-Temperature Argon Plasma
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Hyun-Kyung Chung, Mi-Young Song, Ji-Won Kwon, Myeong-Geon Lee, Jihoon Park, Namjae Bae, Jeamin Song, Gon-Ho Kim, Dipti, and Yuri Ralchenko
- Subjects
argon optical emission spectroscopy ,plasma processing ,coronal models ,collisional-radiative model ,nonlocal thermodynamic equilibrium plasmas ,population kinetics ,Nuclear and particle physics. Atomic energy. Radioactivity ,QC770-798 - Abstract
Optical emission spectroscopy has been widely used in low-temperature argon plasma diagnostics. A coronal model is usually used to analyze the measured line ratios for diagnostics with a single temperature and density. However, many plasma processing conditions deviate from single temperature and density, optically thin conditions, or even coronal plasma conditions due to cascades from high-lying states. In this paper, we present a collisional-radiative model to investigate the validity of coronal approximations over a range of plasma conditions of Te = 1–4 eV and Ne = 108–1013 cm−3. The commonly used line ratios are found to change from a coronal limit where they are independent of Ne to a collisional-radiative regime where they are not. The effects of multiple-temperature plasma, radiation trapping, wall neutralization, and quenching on the line ratios are investigated to identify the plasma conditions under which these effects are significant. This study demonstrates the importance of the completeness of atomic datasets in applying a collisional-radiative model to low-temperature plasma diagnostics.
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- 2021
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8. Cardiac Arrest Related to Torsades de Pointes in a Patient Recovering from Diabetic Ketoacidosis
- Author
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Ju Yeop Lee, Won Sang Yoo, Hyun-Kyung Chung, Myung Yong Lee, and Jinmo Kim
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medicine.medical_specialty ,endocrine system diseases ,Diabetic ketoacidosis ,business.industry ,Internal medicine ,Cardiology ,nutritional and metabolic diseases ,Medicine ,Torsades de pointes ,business ,medicine.disease - Abstract
Diabetic ketoacidosis (DKA) is an acute complication related to severe hyperglycemia. While the mortality rate for DKA is low with appropriate therapy, several complications may lead to deterioration of the clinical course. Here, we report a case of a 23-year-old patient with DKA who suffered from a rare but hemodynamically unstable cardiac arrhythmia, polymorphic ventricular tachycardia with prolonged QT interval, or Torsades de Pointes. During the recovery phase of DKA, three episodes of Torsades de Pointes suddenly occurred, and were recovered by immediate defibrillation. The patient did not have structural heart disease or a genetic predisposition. To the best of our knowledge, this is the first report of an adult with DKA complicated with QT prolongation related to Torsades de Points after correction of ketosis. To manage DKA, more attention may be needed on changes in the QT interval as well as risk factors for Torsades de Points.
- Published
- 2021
- Full Text
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9. The constraint of plasma power balance on runaway avoidance
- Author
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Christopher J. McDevitt, Xian-Zhu Tang, Christopher J. Fontes, Prashant Sharma, and Hyun-Kyung Chung
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Plasma Physics (physics.plasm-ph) ,Nuclear and High Energy Physics ,FOS: Physical sciences ,Condensed Matter Physics ,Physics - Plasma Physics - Abstract
In a post-thermal-quench plasma, mitigated or unmitigated, the plasma power balance is mostly between collisional or Ohmic heating and plasma radiative cooling. In a plasma of atomic mixture { n α } with α labeling the atomic species, the power balance sets the plasma temperature, ion charge state distribution { n α i } with i the charge number, and through the electron temperature T e and ion charge state distribution { n α i } , the parallel electric field E ∥ . Since the threshold electric field for runaway avalanche growth E a v is also set by the atomic mixture, ion charge state distribution and its derived quantity, the electron density n e , the plasma power balance between Ohmic heating and radiative cooling imposes a stringent constraint on the plasma regime for avoiding and minimizing runaways when a fusion-grade tokamak plasma is rapidly terminated.
- Published
- 2022
10. Non-thermal evolution of dense plasmas driven by intense x-ray fields
- Author
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Shenyuan Ren, Yuanfeng Shi, Quincy Y. van den Berg, Muhammad F. Kasim, Hyun-Kyung Chung, Elisa V. Fernandez-Tello, Pedro Velarde, Justin S. Wark, and Sam M. Vinko
- Subjects
Plasma Physics (physics.plasm-ph) ,High Energy Physics - Theory ,High Energy Physics - Theory (hep-th) ,FOS: Physical sciences ,General Physics and Astronomy ,Physics - Plasma Physics - Abstract
The advent of x-ray free-electron lasers (XFELs) has enabled a range of new experimental investigations into the properties of matter driven to extreme conditions via intense x-ray-matter interactions. The femtosecond timescales of these interactions lead to the creation of transient high-energy-density plasmas, where both the electrons and the ions may be far from local thermodynamic equilibrium (LTE). Predictive modelling of such systems remains challenging because of the substantially different timescales on which electrons and ions thermalize, and because of the vast number of atomic configurations that are required to describe the resulting highly-ionized plasmas. Here we explore the evolution of systems driven to high energy densities using CCFLY, a non-LTE, Fokker-Planck collisional-radiative code. We use CCFLY to investigate the evolution dynamics of a solid-density plasma driven by an XFEL, and explore the relaxation of the plasma to local thermodynamic equilibrium on femtosecond timescales in terms of the charge state distribution, electron density, and temperature.
- Published
- 2022
11. Subclinical Hypothyroidism: Prevalence, Health Impact, and Treatment Landscape
- Author
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Hyun Kyung Chung and Won Sang Yoo
- Subjects
Thyroid Hormones ,Pediatrics ,medicine.medical_specialty ,endocrine system ,diagnosis ,Endocrinology, Diabetes and Metabolism ,Health impact ,prevalence ,Levothyroxine ,Reference range ,Review Article ,Hyperthyroidism ,Diseases of the endocrine glands. Clinical endocrinology ,Autoimmune thyroiditis ,Endocrinology ,Hypothyroidism ,Pregnancy ,medicine ,Humans ,Aged ,Subclinical infection ,Thyroid ,treatment ,business.industry ,medicine.disease ,RC648-665 ,Confidence interval ,subclinical hypothyroidism ,Thyroxine ,Female ,Differential diagnosis ,business ,medicine.drug ,Hormone - Abstract
Subclinical hypothyroidism (sHypo) is defined as normal serum free thyroid hormone levels coexisting with elevated serum thyroid-stimulating hormone (TSH) levels. sHypo is a common condition observed in clinical practice with several unique features. Its diagnosis should be based on an understanding of geographic and demographic differences in biochemical criteria versus a global reference range for TSH that is based on the 95% confidence interval of a healthy population. During the differential diagnosis, it is important to remember that a considerable proportion of sHypo cases are transient and reversible in nature; the focus is better placed on persistent or progressive forms, which mainly result from chronic autoimmune thyroiditis. Despite significant evidence documenting the health impacts of sHypo, the effects of levothyroxine treatment (LT4-Tx) in patients with sHypo remains controversial, especially in patients with grade 1 sHypo and older adults. Existing evidence suggests that it is reasonable to refrain from immediate LT4-Tx in most patients if they are closely monitored, except in women who are pregnant or in progressive cases. Future research is needed to further characterize the risks and benefits of LT4-Tx in different patient cohorts.
- Published
- 2021
12. A Case of an Elderly Graves' Patient with Fatal Pulmonary Embolism
- Author
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Won Sang Yoo, Hyun-Kyung Chung, and Joo Yeop Lee
- Subjects
medicine.medical_specialty ,business.industry ,Internal medicine ,General Engineering ,medicine ,Cardiology ,General Earth and Planetary Sciences ,business ,medicine.disease ,General Environmental Science ,Pulmonary embolism - Published
- 2021
- Full Text
- View/download PDF
13. Analysis on the FLYCHK opacity of X-pinch wire materials
- Author
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Min Sang Cho, Byoung-ick Cho, Sang June Hahn, J. H. Sohn, and Hyun-Kyung Chung
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010302 applied physics ,Range (particle radiation) ,Materials science ,Opacity ,Scattering ,General Physics and Astronomy ,chemistry.chemical_element ,02 engineering and technology ,Plasma ,Tungsten ,021001 nanoscience & nanotechnology ,01 natural sciences ,Computational physics ,chemistry ,Molybdenum ,0103 physical sciences ,Radiative transfer ,Pinch ,0210 nano-technology - Abstract
The plasma opacities of the widely used X-pinch target materials (Cu, Mo, W) are calculated over a wide temperature and density range (T = 10–3–102 keV, ρ = 1016–1024 cm−3) by using the collisional radiative code FLYCHK. Including the scattering effect, the FLYCHK opacity of the mid-Z element copper is in good agreement with the Los Alamos opacity code ATOMIC in the broad T–ρ range corresponding to typical X-pinch plasma conditions. In a strongly coupled region, a few corrections, such as the degeneracy effect for the free–free opacity, may be required to improve accuracies. The absence of a Δn = 0 transition and the simple scattering opacity formula in FLYCHK also cause the characteristics of the FLYCHK opacity data. The plasma opacities of the high-Z elements molybdenum and tungsten are also calculated. These results can be used as basic inputs for various radiative hydrodynamic simulations not only for X-pinch plasmas but for different types of high-energy–density plasma research.
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- 2021
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14. The Management of Thyroid Disease in COVID-19 Pandemic
- Author
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Hyun Kyung Chung and Yoo Won Sang
- Subjects
Pediatrics ,medicine.medical_specialty ,Coronavirus disease 2019 (COVID-19) ,business.industry ,Thyroid disease ,Pandemic ,Medicine ,business ,medicine.disease - Published
- 2020
- Full Text
- View/download PDF
15. Cost Assessment of a Tokamak Fusion Reactor with an Inventive Method for Optimum Build Determination
- Author
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Gahyung Jo, Hyun-Kyung Chung, Bong-Guen Hong, Ara Cho, and Jae-Min Kwon
- Subjects
Neutron transport ,Technology ,Control and Optimization ,Tokamak ,Renewable Energy, Sustainability and the Environment ,Nuclear engineering ,Energy Engineering and Power Technology ,Solenoid ,Fusion power ,law.invention ,tokamak fusion reactor ,coupled systems analysis ,law ,Range (aeronautics) ,cost assessment ,Capital cost ,Electric power ,Electrical and Electronic Engineering ,Cost of electricity by source ,Engineering (miscellaneous) ,Energy (miscellaneous) - Abstract
An inventive method was applied to determine the minimum major radius, R0, and the optimum build of a tokamak fusion reactor that simultaneously meets all physics, engineering, and neutronics constraints. With a simple cost model, tokamak systems analyses were carried out over ranges of system parameters to find an optimum build of a tokamak fusion reactor at minimum cost. The impact of a wide range of physics parameters and advanced engineering elements on costs were also addressed. When a central solenoid was used to ramp up a plasma current, design solutions with a cost of electricity (COE) between 109 and 140 mills/kWh, direct capital cost between 5000 and 6000 M/USD, and net electric power, Pe between 1000 and 1600 MW could be found with a minimum R0 between 6.0 and 7.0 m, and fusion power, Pfusion between 2000 and 2800 MW. When the plasma current was driven by a non-inductive external system, the system size and costs could be reduced further; a COE between 98 and 130 mills/kWh, direct capital cost between 4000 and 5000 M$, and Pe between 1000 and 1420 MW could be found with a minimum R0 between 5.1 and 6.7 m, and Pfusion between 2000 and 2650 MW.
- Published
- 2021
16. Modeling α-Synuclein Propagation with Preformed Fibril Injections
- Author
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Dayana Perez-Acuña, Hyun Kyung Chung, Seung-Jae Lee, and Hoang-Anh Ho
- Subjects
medicine.medical_specialty ,Neurology ,Parkinson's disease ,Central nervous system ,Review Article ,Protein aggregation ,Fibril ,lcsh:RC346-429 ,lcsh:RC321-571 ,Alpha-synuclein ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Atrophy ,0502 economics and business ,Medicine ,lcsh:Neurosciences. Biological psychiatry. Neuropsychiatry ,lcsh:Neurology. Diseases of the nervous system ,Dementia with Lewy bodies ,business.industry ,05 social sciences ,medicine.disease ,nervous system diseases ,Animal models ,medicine.anatomical_structure ,chemistry ,nervous system ,Parkinson’s disease ,Biophysics ,α synuclein ,Neurology (clinical) ,Erratum ,business ,Neuroscience ,050203 business & management ,030217 neurology & neurosurgery - Abstract
The aggregation of α-synuclein (α-syn) has been implicated in the pathogenesis of many neurodegenerative disorders, including Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). Postmortem analyses of α-syn pathology, especially that of PD, have suggested that aggregates progressively spread from a few discrete locations to wider brain regions. The neuron-to-neuron propagation of α-syn has been suggested to be the underlying mechanism by which aggregates spread throughout the brain. Many cellular and animal models has been created to study cell-to-cell propagation. Recently, it has been shown that a single injection of preformed fibrils (PFFs) made of recombinant α-syn proteins into various tissues and organs of many different animal species results in widespread α-syn pathology in the central nervous system (CNS). These PFF models have been extensively used to study the mechanism by which aggregates spread throughout the brain. Here, we review what we have learned from PFF models, describe the nature of PFFs and the neuropathological features, neurophysiological characteristics, and behavioral outcomes of the models.
- Published
- 2020
- Full Text
- View/download PDF
17. Recommended electron-impact excitation and ionization cross sections for Be I
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Hyun-Kyung Chung, Oleg Zatsarinny, Dmitry V. Fursa, Klaus Bartschat, Igor Bray, Tapasi Das, Yu. Ralchenko, Dipti, and Connor Ballance
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Physics ,Nuclear and High Energy Physics ,010308 nuclear & particles physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Original data ,Ionization ,0103 physical sciences ,Physics::Atomic Physics ,Limit (mathematics) ,Atomic physics ,010306 general physics ,Close coupling ,Electron ionization ,Excitation - Abstract
Analytic fits to the recommended electron-impact excitation and ionization cross sections for Be I are presented. The lowest 19 terms of configurations 2 s n l ( n ≤ 4) and 2 p 2 terms below the first ionization limit are considered. The fits are based on the accurate calculations with the convergent close coupling (CCC) method as well as the B-spline R-matrix (BSR) approach. The fitted cross sections provide rate coefficients that are believed to approximate the original data within 10% with very few exceptions. The oscillator strengths for the dipole-allowed transitions between all the considered states are calculated with the relativistic multi-configuration Dirac–Hartree–Fock (MCDHF) approach and compared with the CCC and BSR results. This comparison shows a very good agreement except for a handful of cases with likely strong cancellations.
- Published
- 2019
- Full Text
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18. Invited Review
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Elżbieta Fortuna-Zaleśna, Bastiaan J. Braams, Daisuke Nishijima, Thomas Schwarz-Selinger, R.P. Doerner, Marek Rubel, E. Safi, Dmitriy Borodin, Kalle Heinola, Christian Linsmeier, Kai Nordlund, Anna Widdowson, Christian Hill, Michael Probst, Hyun-Kyung Chung, Gregory De Temmerman, Juri Romazanov, S. Brezinsek, Institut des Hautes Etudes pour l’Innovation et l’Entrepreneuriat (IHEIE) (IHEIE), Mines Paris - PSL (École nationale supérieure des mines de Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), International Atomic Energy Agency [Vienna] (IAEA), Forschungszentrum Jülich GmbH | Centre de recherche de Juliers, Helmholtz-Gemeinschaft = Helmholtz Association, Center for Energy Research [La Jolla], University of California [San Diego] (UC San Diego), University of California (UC)-University of California (UC), Royal Institute of Technology [Stockholm] (KTH ), Warsaw University of Technology [Warsaw], Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Helsinki Institute of Physics (HIP), Helsingin yliopisto = Helsingfors universitet = University of Helsinki, Leopold Franzens Universität Innsbruck - University of Innsbruck, Max-Planck-Institut für Plasmaphysik [Garching] (IPP), Culham Science Centre [Abingdon], Centrum Wiskunde & Informatica (CWI), Korea Institute of Fusion Energy, European Project, Centrum Wiskunde & Informatica, Amsterdam (CWI), The Netherlands, MINES ParisTech - École nationale supérieure des mines de Paris, University of California-University of California, University of Helsinki, University of Innsbruck, Department of Physics, Helsinki Institute of Sustainability Science (HELSUS), Helsinki Institute of Urban and Regional Studies (Urbaria), and Doctoral Programme in Materials Research and Nanosciences
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Nuclear and High Energy Physics ,JET-ILW ,Materials Science (miscellaneous) ,Nuclear engineering ,chemistry.chemical_element ,114 Physical sciences ,01 natural sciences ,ISOTOPE RETENTION ,010305 fluids & plasmas ,[SPI]Engineering Sciences [physics] ,NEUTRON-IRRADIATED BERYLLIUM ,0103 physical sciences ,Plasma-facing material ,010306 general physics ,Erosion-deposition ,Erosion–deposition ,[PHYS]Physics [physics] ,DEUTERIUM RETENTION ,TK9001-9401 ,CORE-LEVEL SHIFTS ,Dust ,Plasma ,Research needs ,respiratory tract diseases ,ION-BEAM ANALYSIS ,ELECTRONIC-STRUCTURE ,Nuclear Energy and Engineering ,chemistry ,Hydrogen fuel ,[SDE]Environmental Sciences ,TRITIUM RELEASE ,Erosion ,Nuclear engineering. Atomic power ,Environmental science ,ITER-LIKE WALL ,Critical assessment ,Beryllium ,BE-9(P,ALPHA(0))LI-6 CROSS-SECTIONS ,Literature survey ,Controlled fusion ,ddc:624 - Abstract
International audience; ITER will use beryllium as a plasma-facing material in the main chamber, covering a total surface area of about 620 m. Given the importance of beryllium erosion and co-deposition for tritium retention in ITER, significant efforts have been made to understand the behaviour of beryllium under fusion-relevant conditions with high particle and heat loads. This paper provides a comprehensive report on the state of knowledge of beryllium behaviour under fusion-relevant conditions: the erosion mechanisms and their consequences, beryllium migration in JET, fuel retention and dust generation. The paper reviews basic laboratory studies, advanced computer simulations and experience from laboratory plasma experiments in linear simulators of plasma–wall interactions and in controlled fusion devices using beryllium plasma-facing components. A critical assessment of analytical methods and simulation codes used in beryllium studies is given. The overall objective is to review the existing set of data with a broad literature survey and to identify gaps and research needs to broaden the database for ITER.
- Published
- 2021
- Full Text
- View/download PDF
19. Effect of TSH Suppression Therapy on Bone Mineral Density in Differentiated Thyroid Cancer: A Systematic Review and Meta-analysis
- Author
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Hwa Young Ahn, Seung Hoon Woo, Won Sang Yoo, Jin-Woo Park, Eun Kyung Lee, Eu Jeong Ku, Hyun Kyung Chung, and Jun Hwa Hong
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Oncology ,medicine.medical_specialty ,Endocrinology, Diabetes and Metabolism ,Clinical Biochemistry ,Osteoporosis ,Thyrotropin ,Context (language use) ,Adenocarcinoma ,Biochemistry ,Hyperthyroidism ,Endocrinology ,Bone Density ,Internal medicine ,Medicine ,Humans ,Thyroid Neoplasms ,Thyroid cancer ,Subclinical infection ,Femoral neck ,Bone mineral ,business.industry ,Biochemistry (medical) ,medicine.disease ,Prognosis ,Confidence interval ,medicine.anatomical_structure ,Meta-analysis ,Thyroidectomy ,business - Abstract
Context Because subclinical hyperthyroidism increases the risk of osteoporosis and fractures, concerns are growing about the long-term skeletal safety of TSH suppression therapy after total thyroidectomy in patients with differentiated thyroid cancer (DTC). Objective We aimed to determine the effect of TSH suppression therapy on bone mineral density (BMD) in DTC patients. Methods We searched PubMed, Embase, the Cochrane library, and other sources. Eligible observational studies included DTC patients who underwent TSH suppression therapy and BMD measurement. Two independent reviewers extracted data on the studies’ characteristics and outcomes and determined their risk of bias. Data were extracted from each study for postmenopausal/premenopausal women’s and men’s lumbar spine (LS), femoral neck (FN), and total hip (TH) BMD and summed using a random-effects meta-analysis model. The weighted mean differences with 95% CIs are expressed for the differences in outcome measurements between groups. Results Seventeen studies (739 patients and 1085 controls) were included for quantitative analysis. In postmenopausal women, TSH suppression therapy showed a significant decrease in LS BMD (-0.03; -0.05, -0.02), and a similar trend was seen in TH. In premenopausal women, TSH suppression therapy significantly increased LS BMD (0.04; 0.02, 0.06) and FN BMD (0.02; 0.01, 0.04). In men, there was no significant association between TSH suppression therapy and BMD at any site compared with the controls. Conclusion Evidence from observational studies suggests that postmenopausal women treated with TSH suppression therapy are at risk for lower BMD. Attention should be paid to long-term skeletal safety in DTC survivors.
- Published
- 2021
20. X-ray Spectroscopic Studies of a Solid-Density Germanium Plasma Created by a Free Electron Laser
- Author
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Shenyuan Ren, G. Pérez-Callejo, Ming-Fu Lin, Oliver Humphries, Tim Brandt van Driel, Ryan Royle, Justin Wark, B. A. Hammel, Hyun-Kyung Chung, Tomáš Burian, T. R. Preston, V. Vozda, and Sam Vinko
- Subjects
Materials science ,chemistry.chemical_element ,Germanium ,Electron ,Photon energy ,01 natural sciences ,lcsh:Technology ,Spectral line ,010305 fluids & plasmas ,Ion ,lcsh:Chemistry ,0103 physical sciences ,Physics::Atomic and Molecular Clusters ,General Materials Science ,Emission spectrum ,010306 general physics ,Instrumentation ,lcsh:QH301-705.5 ,Fluid Flow and Transfer Processes ,solid density ,lcsh:T ,Process Chemistry and Technology ,General Engineering ,Free-electron laser ,Plasma ,lcsh:QC1-999 ,3. Good health ,Computer Science Applications ,germanium ,LCLS ,chemistry ,lcsh:Biology (General) ,lcsh:QD1-999 ,lcsh:TA1-2040 ,X-ray spectroscopy ,Physics::Accelerator Physics ,Atomic physics ,lcsh:Engineering (General). Civil engineering (General) ,lcsh:Physics - Abstract
The generation of solid-density plasmas in a controlled manner using an X-ray free electron laser (XFEL) has opened up the possibility of diagnosing the atomic properties of hot, strongly coupled systems in novel ways. Previous work has concentrated on K-shell emission spectroscopy of low Z (<, = 14) elements. Here, we extend these studies to the mid-Z(=32) element Germanium, where the XFEL creates copious L-shell holes, and the plasma conditions are interrogated by recording of the associated L-shell X-ray emission spectra. Given the desirability of generating as uniform a plasma as possible, we present here a study of the effects of the FEL photon energy on the temperatures and electron densities created, and their uniformity in the FEL beam propagation direction. We show that good uniformity can be achieved by tuning the photon energy of the XFEL such that it does not overlap significantly with L-shell to M-shell bound-bound transitions, and lies below the L-edges of the ions formed during the heating process. Reasonable agreement between experiment and simulations is found for the emitted X-ray spectra, demonstrating that for these higher Z elements, the selection of appropriate XFEL parameters is important for achieving uniformity in the plasma conditions.
- Published
- 2020
21. A planning study for virtual DEMO development in Korea
- Author
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Ara Cho, Jae-Min Kwon, Hyun-Kyung Chung, Juhyung Kim, Jisung Kang, Won-Jae Choi, and Eun Sang Lee
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Nuclear Energy and Engineering ,Mechanical Engineering ,General Materials Science ,Civil and Structural Engineering - Published
- 2022
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22. Understanding how minority relativistic electron populations may dominate charge state balance and radiative cooling of a post-thermal quench tokamak plasma
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Nathan A. Garland, Hyun-Kyung Chung, Mark C. Zammit, Christopher J. McDevitt, James Colgan, Christopher J. Fontes, and Xian-Zhu Tang
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Condensed Matter Physics - Published
- 2022
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23. A Case Study on PhiloGraphics and importance of humanities in design - A Case Study on Jenes Carreras
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Jae-hyung Kim and Hyun-kyung Chung
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Library science ,General Medicine ,Sociology - Published
- 2018
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- View/download PDF
24. Addition of Genetics to Quantitative MRI Facilitates Earlier Prediction of Dementia: A Non-invasive Alternative to Amyloid Measures
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Lei Huang, Naisha Shah, Ilan Shomorony, Jian Wu, Nafisa Bulsara, Christine Leon Swisher, Lei Yang, David S. Karow, Hyun-Kyung Chung, James B. Brewer, Dmitry Tkach, Graff Alexander M, Natalie M. Schenker-Ahmed, Svetlana Bureeva, Robyn Heister, Peter Garst, Wayne Delport, Tetiana Dadakova, and Arya Iranmehr
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Genetics ,0303 health sciences ,Proportional hazards model ,business.industry ,Concordance ,Context (language use) ,medicine.disease ,3. Good health ,03 medical and health sciences ,0302 clinical medicine ,medicine ,Dementia ,Brain segmentation ,Biomarker (medicine) ,Age of onset ,business ,030217 neurology & neurosurgery ,Survival analysis ,030304 developmental biology - Abstract
SUMMARYBackgroundAlzheimer’s disease is a major health problem, affecting ~4⋅5% of people aged 60 and older in 2016 with over 43 million affected globally1. The traditional approach for detection evaluates an individual in the presence of symptoms. However, it has been established that amyloid deposits begin to accumulate years before symptoms begin to appear2,3. With improved technology, there is increased focus on risk reduction, timely diagnosis, and early intervention. Early identification of at-risk individuals may enable patients and their families to better prepare for and reduce the impact of this condition.MethodsWe obtained data for patients from two longitudinal retrospective cohorts (Alzheimer’s Disease Neuroimaging Initiative: ADNI and National Alzheimer’s Coordinating Center: NACC), including T1-weighted MRI and genetics data. The polygenic risk score (PRS) used in this study was built based on a published Genome Wide Association Study (GWAS) that identified variants associated with Alzheimer’s disease. Quantitative MRI features were obtained using a 3D U-Net neural network for brain segmentation. Cox proportional hazards (CPH) regression models were used with subjects censored at death or the last evaluation. Time-to-event was defined as the time it takes for an individual who is dementia-free at the baseline MRI to progress to dementia as defined by the criteria described by ADNI. Time-dependent ROC areas under curve (AUCs) were estimated in the presence of censored data. The time-dependent AUCs were compared among models using the Wilcoxon rank sum test for dependent samples. Data was binned into three groups according to survival probability to eight years after baseline and Kaplan-Meier survival analysis was used to estimate the probability of surviving at least to time t. Calibration for both training and validation cohorts was evaluated using the predicted survival probability, splitting samples into five risk groups of equal size based on the predicted survival probability.FindingsWe developed a model that predicts the onset of dementia over an eight-year time window in individuals with genetics data and a T1-weighted MRI who were dementia-free at baseline. We then validated the model in an independent multisite cohort.We observed that models using PRS in addition to MRI-derived features performed significantly better as measured by time-varying AUC up to eight years in both the training (p = 0⋅0071) and validation (p = 0⋅050) cohorts. We observed improved performance of the two modalities versus MRI alone when compared with more invasive amyloid measures. The combined MRI and PRS model showed equivalent performance to cerebral spinal fluid (CSF) amyloid measurement up to eight years prior to disease onset (p = 0⋅181) and while the MRI only model performed worse (p = 0⋅040). Finally, we compared to amyloid positron emission tomography (PET) three to four years prior to disease onset with favorable results.InterpretationOur finding suggests that the two modalities are complementary measures, in that MRI reflects near-term decline and the addition of genetics extends the prediction scope of quantitative MRI by adding additional long-term predictive power.The proposed multimodal model shows potential as an alternate solution for early risk assessment given the concordance with CSF amyloid and amyloid PET. Future work will include further comparison with amyloid PET (greater than four years) and with CSF (greater than eight years) as additional long-term data becomes available. Also, the model will be evaluated for its clinical utility in the “active surveillance” of individuals who may be concerned about their risk of developing dementia but are not yet eligible for assessment by amyloid PET or CSF.RESEARCH IN CONTEXTEvidence before this studyThe most significant known genetic factor in Alzheimer’s disease (AD) is the ε4 allele for theApolipoprotein E(APOE) gene. Carriers of the allele have a three-fold increased risk of developing AD, whereas individuals who are homozygous have a 15-fold increased risk. Genome-wide association studies (GWASs) have identified many additional genetic variants that are associated with AD. Recent studies have shown that the risk for AD is better predicted by combining effects from several genetic variants into “polygenic risk scores” (PRS). Studies have also demonstrated that the age of onset for AD is better predicted using PRS rather thanAPOEstatus alone. Regional brain atrophy, as measured using volumetric MRI, is also an important biomarker for evaluating an individual’s risk of developing dementia. Previous predictions have shown that medial temporal lobe atrophy, as measured by a Hippocampal Occupancy Score (HOC) is highly associated with progression from MCI to AD.Added value of this studyIn the proposed model, the addition of genetics to MRI data lengthens the time over which the model can predict onset of dementia. The two measures appear to be complementary, with MRI showing near-term decline and genetics providing additional predictive power in the long-term. When compared to more invasive measures of amyloid, which have been shown to have long-term predictive power, we observed equivalent performance to CSF amyloid up to 8 years prior to disease onset and equivalent performance to amyloid PET three to four years prior to disease onset.Implications of all the available evidenceAlthough MRI remains relatively expensive, it is less expensive, less invasive, more accessible, and more commonly available than amyloid PET. Furthermore, MRI is already part of standard clinical practice and this model may be applied to standard clinical MRIs with no additional acquisition required. A recent survey of patients and their caregivers has highlighted a desire for access to better diagnostics, such as amyloid PET, to aid them in long-term legal, financial and healthcare planning. Our model, given the concordance with CSF and amyloid PET could be an alternate solution to fulfill this need. Furthermore, our model could facilitate the “active surveillance” of individuals who are high-risk and thereby enhance the possibility of early intervention.
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- 2019
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25. Impact of free electron degeneracy on collisional rates in plasmas
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Gareth O. Williams, V. Hilbert, Marta Fajardo, S. Künzel, Bianca Iwan, B. Barbrel, P. Zeitoun, Willem Boutu, A. I. Gonzalez, Eduardo Granados, Philip Heimann, Byoung-ick Cho, S. Daboussi, Howard A. Scott, Ulf Zastrau, Eric Galtier, Richard W. Lee, Bob Nagler, Hae Ja Lee, Hamed Merdji, Hyun-Kyung Chung, P. Renaudin, and Publica
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Free electron model ,Physics ,Code (set theory) ,Degenerate energy levels ,FOS: Physical sciences ,Plasma ,01 natural sciences ,Measure (mathematics) ,Physics - Plasma Physics ,010305 fluids & plasmas ,Plasma Physics (physics.plasm-ph) ,Physics::Plasma Physics ,Quantum electrodynamics ,0103 physical sciences ,Degeneracy (biology) ,010306 general physics ,Computer Science::Databases - Abstract
Degenerate plasmas, in which quantum effects dictate the behavior of free electrons, are ubiquitous on earth and throughout space. Transitions between bound and free electron states determine basic plasma properties, yet the effects of degeneracy on these transitions have only been theorized. Here, we use an x-ray free electron laser to create and characterize a degenerate plasma. We observe a core electron fluorescence spectrum that cannot be reproduced by models that ignore free electron degeneracy. We show that degeneracy acts to restrict the available electron energy states, thereby slowing the rate of transitions to and from the continuum. We couple degeneracy and bound electron dynamics in an existing collisional-radiative code, which agrees well with observations. The impact of the shape of the cross section, and hence the magnitude of the correction due to degeneracy, is also discussed. This study shows that degeneracy in plasmas can significantly influence experimental observables such as the emission spectra, and that these effects can be included parametrically in well-established atomic physics codes. This work narrows the gap in understanding between the condensed-matter and plasma phases, which coexist in myriad scenarios.
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- 2019
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26. Review of the 10th Non-LTE Code Comparison Workshop
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Christopher J. Fontes, Howard A. Scott, Hyun-Kyung Chung, Stephanie Hansen, Yu. Ralchenko, and Evgeny Stambulchik
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Plasma Physics (physics.plasm-ph) ,Nuclear and High Energy Physics ,Radiation ,Computer science ,Nuclear engineering ,0103 physical sciences ,Code (cryptography) ,FOS: Physical sciences ,010306 general physics ,01 natural sciences ,Dense matter ,Physics - Plasma Physics ,010305 fluids & plasmas - Abstract
We report on the results of the 10th Non-LTE code comparison workshop, which was held at the University of San Diego campus November 28 through December 1, 2017. Non-equilibrium collisional-radiative models predict the electronic state populations and attendant emission and absorption characteristics of hot, dense matter and are used to help design and diagnose high-energy-density experiments. At this workshop, fifteen codes from eleven institutions contributed results for steady-state and time-dependent neon, aluminum, silicon, and chlorine cases relevant to a variety of high-density experimental and radiation-driven astrophysical systems. This report focuses on differences in the predictions from codes with different internal structure, completeness, density effects, and rate fidelity and the impact of those differences on hot, dense plasma diagnostics., Comment: submitted to HEDP
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- 2019
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27. Effect of TSH Suppression Therapy on Bone Mineral Density in Differentiated Thyroid Cancer: A Systematic Review and Meta-analysis.
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Eu Jeong Ku, Won Sang Yoo, Eun Kyung Lee, Hwa Young Ahn, Seung Hoon Woo, Jun Hwa Hong, Hyun Kyung Chung, Jin-Woo Park, Ku, Eu Jeong, Yoo, Won Sang, Lee, Eun Kyung, Ahn, Hwa Young, Woo, Seung Hoon, Hong, Jun Hwa, Chung, Hyun Kyung, and Park, Jin-Woo
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THYROTROPIN ,THYROID cancer ,OSTEOPOROSIS ,ADENOCARCINOMA ,RESEARCH ,THYROIDECTOMY ,META-analysis ,HYPERTHYROIDISM ,THYROID gland tumors ,RESEARCH methodology ,SYSTEMATIC reviews ,PROGNOSIS ,MEDICAL cooperation ,EVALUATION research ,COMPARATIVE studies ,RESEARCH funding ,BONE density - Abstract
Context: Because subclinical hyperthyroidism increases the risk of osteoporosis and fractures, concerns are growing about the long-term skeletal safety of TSH suppression therapy after total thyroidectomy in patients with differentiated thyroid cancer (DTC).Objective: We aimed to determine the effect of TSH suppression therapy on bone mineral density (BMD) in DTC patients.Methods: We searched PubMed, Embase, the Cochrane library, and other sources. Eligible observational studies included DTC patients who underwent TSH suppression therapy and BMD measurement. Two independent reviewers extracted data on the studies' characteristics and outcomes and determined their risk of bias. Data were extracted from each study for postmenopausal/premenopausal women's and men's lumbar spine (LS), femoral neck (FN), and total hip (TH) BMD and summed using a random-effects meta-analysis model. The weighted mean differences with 95% CIs are expressed for the differences in outcome measurements between groups.Results: Seventeen studies (739 patients and 1085 controls) were included for quantitative analysis. In postmenopausal women, TSH suppression therapy showed a significant decrease in LS BMD (-0.03; -0.05, -0.02), and a similar trend was seen in TH. In premenopausal women, TSH suppression therapy significantly increased LS BMD (0.04; 0.02, 0.06) and FN BMD (0.02; 0.01, 0.04). In men, there was no significant association between TSH suppression therapy and BMD at any site compared with the controls.Conclusion: Evidence from observational studies suggests that postmenopausal women treated with TSH suppression therapy are at risk for lower BMD. Attention should be paid to long-term skeletal safety in DTC survivors. [ABSTRACT FROM AUTHOR]- Published
- 2021
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28. Model uncertainties of local-thermodynamic-equilibrium K-shell spectroscopy
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Roberto Mancini, G. Loisel, F. Gilleron, Joseph J. MacFarlane, Ph. Cosse, Gregory Rochau, Carlos A. Iglesias, Hyun-Kyung Chung, Ricardo Florido, Richard W. Lee, James Colgan, Stephanie Hansen, Taisuke Nagayama, James E. Bailey, Chris Fontes, D. P. Kilcrease, G. Faussurier, M. E. Sherrill, Jean-Christophe Pain, C. Blancard, and Igor Golovkin
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Physics ,Nuclear and High Energy Physics ,X-ray spectroscopy ,Electron density ,Radiation ,Opacity ,Thermodynamic equilibrium ,business.industry ,Electron shell ,01 natural sciences ,010305 fluids & plasmas ,Optics ,0103 physical sciences ,Electron temperature ,Plasma diagnostics ,Atomic physics ,010306 general physics ,Spectroscopy ,business - Abstract
Local-thermodynamic-equilibrium (LTE) K-shell spectroscopy is a common tool to diagnose electron density, ne, and electron temperature, Te, of high-energy-density (HED) plasmas. Knowing the accuracy of such diagnostics is important to provide quantitative conclusions of many HED-plasma research efforts. For example, Fe opacities were recently measured at multiple conditions at the Sandia National Laboratories Z machine (Bailey et al., 2015), showing significant disagreement with modeled opacities. Since the plasma conditions were measured using K-shell spectroscopy of tracer Mg (Nagayama et al., 2014), one concern is the accuracy of the inferred Fe conditions. In this article, we investigate the K-shell spectroscopy model uncertainties by analyzing the Mg spectra computed with 11 different models at the same conditions. We find that the inferred conditions differ by ±20–30% in ne and ±2–4% in Te depending on the choice of spectral model. Also, we find that half of the Te uncertainty comes from ne uncertainty. To refine the accuracy of the K-shell spectroscopy, it is important to scrutinize and experimentally validate line-shape theory. We investigate the impact of the inferred ne and Te model uncertainty on the Fe opacity measurements. Its impact is small and does not explain the reported discrepancies.
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- 2016
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29. Opacity calculation for aluminum, iron, and gold plasmas using FLYCHK code
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Byoung-ick Cho, Hyun-Kyung Chung, S.J. Hahn, S. Fujioka, Min Sang Cho, and Kazuki Matsuo
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education.field_of_study ,Radiation ,Materials science ,010504 meteorology & atmospheric sciences ,Opacity ,Population ,chemistry.chemical_element ,Plasma ,Kinetic energy ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Spectral line ,Ion ,Computational physics ,chemistry ,Aluminium ,education ,Spectroscopy ,0105 earth and related environmental sciences - Abstract
The opacity information of a finite-temperature plasma is an important property and requires the population distribution of a given plasma condition. A population kinetic code for plasma spectroscopy, FLYCHK, has been widely used by researchers to study the spectroscopic properties of high-energy-density plasmas under a wide range of conditions. In this study, the FLYCHK calculation of the Planck and Rosseland mean opacities of low- to high-Z elements, such as aluminum (Z = 13), iron (Z = 26), and gold (Z = 79), under a wide temperature and density range (T = 10−3–102 keV, ρ = 10−6–102 g/cc) is reported. This study mainly focused on the quantitative comparisons of FLYCHK opacities with commonly used opacities: ATOMIC and PROPACEOS. Comparisons show that the FLYCHK mean opacities are comparable to other results over a wide range of plasma conditions. Aluminum opacities were analyzed in detail to understand the characteristics of FLYCHK opacity simulations.
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- 2020
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30. Impact of a minority relativistic electron tail interacting with a thermal plasma containing high-atomic-number impurities
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Tim Wildey, Hyun-Kyung Chung, Nathan A. Garland, Mark C. Zammit, Christopher J. Fontes, Xian-Zhu Tang, James Colgan, Todd Elder, and Chris McDevitt
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Physics ,Atomic Physics (physics.atom-ph) ,FOS: Physical sciences ,food and beverages ,Plasma ,Electron ,Condensed Matter Physics ,Physics - Plasma Physics ,Physics - Atomic Physics ,Ion ,Plasma Physics (physics.plasm-ph) ,Orders of magnitude (time) ,Physics::Plasma Physics ,Ionization ,Stopping power (particle radiation) ,Electron temperature ,Atomic physics ,Collisional excitation - Abstract
A minority relativistic electron component can arise in both laboratory and naturally occurring plasmas. In the presence of high-atomic-number ion species, the ion charge state distribution at a low bulk electron temperature can be dominated by relativistic electrons, even though their density is orders of magnitude lower. This is due to the relativistic enhancement of the collisional excitation and ionization cross sections. The resulting charge state effect can dramatically impact the radiative power loss rate and the related Bethe stopping power of relativistic electrons in a dilute plasma.
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- 2020
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31. Iso-nuclear tungsten dielectronic recombination rates for use in magnetically-confined fusion plasmas
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N. R. Badnell, Won Ae Lee, Chris Fontes, T. Nakano, James Colgan, M. G. O'Mullane, S. P. Preval, Bowen Li, Y.B. Fu, Hyun-Kyung Chung, D.-H. Kwon, Ehud Behar, Bastiaan J. Braams, Connor Ballance, Xiaobin Ding, Chenzhong Dong, and Multiscale Dynamics
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Nuclear and High Energy Physics ,Chemistry ,Fusion plasma ,Experimental data ,chemistry.chemical_element ,Tungsten ,7. Clean energy ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,010305 fluids & plasmas ,Ion ,Nuclear physics ,0103 physical sciences ,Atomic physics ,010306 general physics ,QC ,Recombination ,Atomic data - Abstract
Under the auspices of the IAEA Atomic and Molecular Data Center and the Korean Atomic Energy Research Institute, our assembled group of authors has reviewed the current state of dielectronic recombination (DR) rate coefficients for various ion stages of tungsten (W). Subsequent recommendations were based upon available experimental data, first-principle calculations carried out in support of this paper and from available recombination data within existing atomic databases. If a recommendation was possible, data were compiled, evaluated and fitted to a functional form with associated uncertainty information retained, where available. This paper also considers the variation of the W fractional abundance due to the underlying atomic data when employing different data sets.
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- 2018
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32. Talk 'Next-Generation Simulations For Xfel-Plasma Interactions With Solid Density Targets With Picongpu'
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Axel Huebl, René Widera, Richard Pausch, Marco Garten, Heiko Burau, Alexander Matthes, Benjamin Worpitz, Fabian Koller, Thomas Kluge, Jan Vorberger, Alexander Debus, Thomas Cowan, Ulrich Schramm, Hyun-Kyung Chung, and Michael Bussmann
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laser-plasma simulation modeling HPC exascale ionization xfel - Abstract
PIConGPU reportedly is the fastest particle-in-cell code in the world with respect to sustained Flop/s. Written in performance-portable, single-source C++ we constantly push the envelope towards Exascale laser-plasma modeling. However, solving previously week-long simulation tasks in a few hours with a speedy framework is only the beginning. This talk will present the architecture and recent additions driving PIConGPU. As we speak, we run on the fastest machines and the community approaches a new generation of TOP10 clusters. Within those, many-core computing architectures and severe limitations in available I/O bandwidth demand fundamental rethinking of established modeling workflows towards in situ-processing. We present our ready-to-use open-source solutions and address scientific repeatability, data-reduction in I/O, predictability and new atomic modeling for XFEL pump-probe experiments., This research used resources of the Oak Ridge Leadership Computing Facility located in the Oak Ridge National Laboratory, which is supported by the Office of Science of the Department of Energy under Contract DE-AC05-00OR22725.
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- 2017
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33. Modelling K shell spectra from short pulse heated buried microdot targets
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Richard W. Lee, E. W. Magee, E.G. Hill, N. Sircombe, John J. L. Morton, M. P. Hill, Hyun-Kyung Chung, E. Marley, J. Nilsen, S. J. Rose, Ronnie Shepherd, J.W.O. Harris, M. Jeffery, Steven James, J. Emig, C. R. D. Brown, David Hoarty, Peter Beiersdorfer, and L. M. R. Hobbs
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Nuclear and High Energy Physics ,Materials science ,Fluids & Plasmas ,PLASMAS ,Electron shell ,01 natural sciences ,010305 fluids & plasmas ,law.invention ,Physics, Fluids & Plasmas ,law ,0103 physical sciences ,DENSE ALUMINUM ,Plasma heating with laser beams ,010306 general physics ,Absorption (electromagnetic radiation) ,Spectroscopy ,ULTRASHORT LASER-PULSES ,HOT ,Science & Technology ,02 Physical Sciences ,Radiation ,Dense plasma spectroscopy ,Physics ,Microdot ,Pulse duration ,Laser ,Physical Sciences ,Electron temperature ,Atomic physics ,Beam divergence - Abstract
K shell X-ray emission measurements have been used to diagnose plasma conditions in short-pulse heated buried microdot targets on the Orion high power laser. These experiments have been used to validate simulations of short pulse laser-solid interaction that combine hybrid PIC modelling of the laser absorption with radiation-hydrodynamics simulations including an electron transport model. Comparison of these simulations with streaked K shell spectroscopy show the importance of including radial gradients in fitting the spectra. An example is presented of the emission of sulphur from a 50 µm diameter microdot sample buried in a plastic foil. Previously agreement between simulation and experiment was obtained only by treating the absorbed energy, electron temperature and beam divergence as fitting parameters. The good agreement obtained in this work used the measured laser energy and laser pulse length and calculated the laser-solid target interaction from first principles.
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- 2017
34. Atomic processes modeling of X-ray free electron laser produced plasmas using SCFLY code
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Byoung-ick Cho, R. W. Lee, O. Ciricosta, Justin Wark, Hyun-Kyung Chung, and Sam Vinko
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Free electron model ,Physics ,Free-electron laser ,Plasma ,Electron ,Laser ,law.invention ,Atomic orbital ,law ,Ionization ,Physics::Atomic and Molecular Clusters ,State of matter ,Physics::Accelerator Physics ,Physics::Atomic Physics ,Atomic physics - Abstract
With the development of X-ray free electron lasers (XFEL), a novel state of matter of highly transient and non-equilibrium plasma has been created in laboratories. As high intensity X-ray laser beams interact with a solid density target, electrons are ionized from inner-shell orbitals and these electrons and XFEL photons create dense and finite temperature plasmas. In order to study atomic processes in XFEL driven plasmas, the atomic kinetics model SCFLY containing an extensive set of configurations needed for solid density plasmas was applied to study atomic processes of XFEL driven systems. The code accepts the time-dependent conditions of the XFEL as input parameters, and computes time-dependent population distributions and ionization distributions self-consistently with electron temperatures and densities assuming an instantaneous equilibration of electron energies. The methods and assumptions in the atomic kinetics model and unique aspects of atomic processes in XFEL driven plasmas are described.
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- 2017
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35. Special Issue on Spectral Line Shapes in Plasmas
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Manuel Á. González, Annette Calisti, Evgeny Stambulchik, and Hyun-Kyung Chung
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Nuclear and High Energy Physics ,Magnetic fusion ,Series (mathematics) ,Computer science ,Spectral line shapes in plasma ,Plasma ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Spectral line ,n/a ,Computer engineering ,Code (cryptography) ,lcsh:QC770-798 ,lcsh:Nuclear and particle physics. Atomic energy. Radioactivity ,Atomic physics ,Spectral line shapes ,33 Ciencias Tecnológicas - Abstract
Producción Científica, Line-shape analysis is one of the most important tools for diagnostics of both laboratory and space plasmas. Its reliable implementation requires sufficiently accurate calculations, which imply the use of analytic methods and computer codes of varying complexity, and, necessarily, varying limits of applicability and accuracy. However, studies comparing different computational and analytic methods are almost non-existent. The Spectral Line Shapes in Plasma (SLSP) code comparison workshop series [1] was established to fill this gap. Numerous computational cases considered in the two workshops organized to date (in April 2012 and August 2013 in Vienna, Austria) not only serve the purpose of code comparison, but also have applications in research of magnetic fusion, astrophysical, laser-produced plasmas, and so on. Therefore, although the first workshop was briefly reviewed elsewhere [2], and will likely be followed by a review of the second one, it was unanimously decided by the participants that a volume devoted to results of the workshops was desired. It is the main purpose of this special issue.
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- 2014
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36. Design of Zeeman spectroscopy experiment with magnetized silicon plasma generated in the laboratory
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Sandrine Ferri, Hyun-Kyung Chung, King Fai Farley Law, John Moody, Shinsuke Fujioka, Kazuki Matsuo, Hiroki Morita, Seung Ho Lee, Chang Liu, Bradley Pollock, and Shohei Sakata
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Nuclear and High Energy Physics ,Radiation ,Materials science ,Zeeman effect ,Spectrometer ,Plasma parameters ,Plasma ,01 natural sciences ,010305 fluids & plasmas ,Magnetic field ,symbols.namesake ,Stark effect ,0103 physical sciences ,symbols ,Atomic physics ,Spectral resolution ,010306 general physics ,Spectroscopy - Abstract
A laboratory measurement of the Zeeman effect in the soft X-ray range can be realized using a laser-produced strong magnetic field and laser-driven magnetic field compression. In this measurement, a pair of laser-driven capacitor-coil targets produces a spatially uniform seed magnetic field of several hundred Tesla, and a low-density SiO2 foam is soaked in the magnetic field. A strongly magnetized high-energy-density SiO2 plasma is then produced by laser-driven compressions of both the foam and the magnetic field. According to a numerical hydrodynamic simulation, a > 10 kT peak magnetic field is achievable with a 100 T seed magnetic field produced by the GEKKO-XII laser facility at Osaka University, Japan. The soft X-ray spectrum is calculated using the MASCB-PPPB code with plasma parameters obtained with the FLASH code. Zeeman splitting of the 4 f − 3 d transition line from lithium-like Si ions of 1.2 eV is observed at 95.4 eV emission peak energy, which is observable even considering the Stark broadening and the spectral resolution of the spectrometer.
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- 2019
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37. Exercise-induced inflammatory responses-reduced a-synuclein aggregation and improve motor function in a transgenic mouse model of Parkinson's disease
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Seung-Jae Lee, He-Jin Lee, Tae-Kyung Kim, Eun-Jin Bae, and Hyun Kyung Chung
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Genetically modified mouse ,Parkinson's disease ,business.industry ,General Neuroscience ,Synuclein ,Medicine ,business ,medicine.disease ,Neuroscience ,Motor function - Published
- 2019
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38. Drug screening for regulating α-synuclein propagation
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Hyun-Kyung Chung, Seung-Jae Lee, and Joo-Ok Min
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Drug ,Chemistry ,General Neuroscience ,media_common.quotation_subject ,α synuclein ,media_common ,Cell biology - Published
- 2019
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39. Spectral Line Shapes in Plasmas II
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Hyun-Kyung Chung, Evgeny Stambulchik, Manuel Á. González, and Annette Calisti
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Physics ,Nuclear and High Energy Physics ,Reprint ,Plasma ,Condensed Matter Physics ,01 natural sciences ,Engineering physics ,Atomic and Molecular Physics, and Optics ,Spectral line ,n/a ,0103 physical sciences ,lcsh:QC770-798 ,lcsh:Nuclear and particle physics. Atomic energy. Radioactivity ,Atomic physics ,010306 general physics ,010303 astronomy & astrophysics - Abstract
For the first two Spectral Line Shapes in Plasma workshops, participants submitted in total over 1,500 line-shape calculations. The studies collected in this Special Issue explore only a part of this immense work. This book is a reprint of the special issue that appeared in the online open access journal Atoms (ISSN 2218-2004) in 2014 (available at: http://www.mdpi.com/journal/atoms/special_issues/SpectralLineShapes).
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- 2019
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40. Medical Treatment of Graves' Disease
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Hyun Kyung Chung
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Pediatrics ,medicine.medical_specialty ,Medical treatment ,business.industry ,Graves' disease ,medicine ,medicine.disease ,business - Published
- 2019
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41. Therapeutic Effect of Quadruple Oral Hypoglycemic Agents in Patients with Type 2 Diabetes Mellitus Who Have Insulin Limitations
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Hyun Kyung Chung, Do Hee Kim, Won Sang Yoo, and Hee Jin Kim
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medicine.medical_specialty ,endocrine system diseases ,Combination therapy ,medicine.drug_class ,business.industry ,Insulin ,medicine.medical_treatment ,nutritional and metabolic diseases ,Type 2 Diabetes Mellitus ,030209 endocrinology & metabolism ,030204 cardiovascular system & hematology ,Hypoglycemia ,medicine.disease ,Gastroenterology ,Sulfonylurea ,Metformin ,03 medical and health sciences ,0302 clinical medicine ,Internal medicine ,Diabetes mellitus ,medicine ,business ,Pioglitazone ,medicine.drug - Abstract
Background: Insulin therapy is the treatment of choice in type 2 diabetes mellitus (T2DM) patients who are not achieving glycemic goals despite triple oral hypoglycemic agent (OHA) combination therapy. However, there is still no additional treatment option for patients who cannot afford insulin therapy or who have various clinical limitations. The purpose of this study was to evaluate the clinical efficacy and safety of four OHA combination therapy in poorly controlled T2DM patients who could not afford insulin therapy. Methods: Forty-seven T2DM patients were enrolled according to the following criteria: 1) glycosylated hemoglobin [HbA1c] > 8.5%, 2) ongoing treatment with 3 OHA combination therapy (metformin, sulfonylurea, dipeptidyl peptidase-4 inhibitor), or 3) combined limitations for applying insulin therapy. Patients were given the fourth OHA (pioglitazone) in addition to their previous treatment for 12 months. We evaluated changes in HbA1c, body weight, hypoglycemic events, and side effects. Results: At study completion, mean HbA1c and fasting plasma glucose were significantly reduced from 9.6% to 8.04% and from 198.4 mg/dL to 161.5 mg/dL, respectively (P < 0.001). Mean body weight was significantly increased from 66.7 kg to 69.3 kg. Hypoglycemia and side effects were observed 18 times and only 3 cases showed abnormal liver function tests or edema. In addition, subjects with higher initial HbA1c levels and HOMA-beta showed an independent association with a greater reduction in HbA1c. Conclusion: The 4 OHA combination therapy is effective and safe when insulin is not feasible.
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- 2019
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42. Spectral Line Shapes in Plasmas
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Evgeny Stambulchik, Annette Calisti, Hyun-Kyung Chung, Gonzalez, Manuel A., Weizmann Institute of Science [Rehovot, Israël], Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), International Atomic Energy Agency [Vienna] (IAEA), Departamento de Optica y Fisica Aplicada, Universidad de Valladolid [Valladolid] (UVa)-Facultad de Ciencias, Evgeny Stambulchik, Annette Calisti, Hyun-Kyung Chung, Manuel A. Gonzalez, Martyn Rittman, and Calisti, Annette
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[PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph] ,[PHYS.PHYS.PHYS-PLASM-PH] Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph] - Abstract
International audience; For the first two Spectral Line Shapes in Plasma workshops, participants submitted in total over 1,500 line-shape calculations. The studies collected in this Special Issue explore only a part of this immense work. This book is a reprint of the special issue that appeared in the online open access journal Atoms (ISSN 2218-2004) in 2014 (available at: http://www.mdpi.com/journal/atoms/special_issues/SpectralLineShapes).
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- 2015
43. Comparison and analysis of collisional-radiative models at the NLTE-7 workshop
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Yu. Ralchenko, Chris Fontes, C. Bowen, Hyun-Kyung Chung, and Stephanie Hansen
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Physics ,Nuclear and High Energy Physics ,Radiation ,Thermodynamic equilibrium ,Krypton ,chemistry.chemical_element ,Spectral line ,Nuclear physics ,Plasma kinetics ,chemistry ,Ionization ,Principal quantum number ,Radiative transfer ,Relaxation (physics) ,Atomic physics - Abstract
We present the main results of the 7th Non-Local Thermodynamic Equilibrium Code Comparison Workshop held in December 2011 in Vienna, Austria. More than twenty researchers from nine countries, who actively work on development of collisional-radiative codes for plasma kinetics modeling, attended the meeting and submitted their results for a number of comparison cases. The cases included free-electron-laser-inspired time-dependent relaxation of photoexcited Ne-like Ar, ionization balance and spectra for highly charged tungsten, spectroscopic diagnostics of krypton L-shell spectra, and an investigation of Ne model convergence with principal quantum number.
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- 2013
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44. Testing the reliability of non-LTE spectroscopic models for complex ions
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C. Bowen, Stephanie Hansen, Jean-Raphael Marques, Hyun-Kyung Chung, Evgeny Stambulchik, Chris Fontes, Olivier Peyrusse, Gregory Armstrong, F. de Dortan, S. Bastiani-Ceccotti, Akira Sasaki, F. Gilleron, F. Thais, Robin Piron, James Colgan, Yu. Ralchenko, and M. Poirier
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Nuclear and High Energy Physics ,Radiation ,Materials science ,Opacity ,Plasma ,Laser ,Spectral line ,law.invention ,Quality (physics) ,law ,Atomic theory ,Metastability ,Electron temperature ,Atomic physics - Abstract
Collisional-radiative atomic models are widely used to help diagnose experimental plasma conditions through fitting and interpreting measured spectra. Here we present the results of a code comparison in which a variety of models determined plasma temperatures and densities by finding the best fit to an experimental L-shell Kr spectrum from a well characterized, but not benchmarked, laser plasma. While variations in diagnostic strategies and qualities of fit were significant, the results generally confirmed the typically quoted uncertainties for such diagnostics of ±20% in electron temperature and factors of about two in density. The comparison also highlighted some model features important for spectroscopic diagnostics: fine structure was required to match line positions and relative intensities within each charge state and for density diagnostics based on emission from metastable states; an extensive configuration set was required to fit the wings of satellite features and to reliably diagnose the temperature through the inferred charge state distribution; and the inclusion of self-consistent opacity effects was an important factor in the quality of the fit.
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- 2013
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45. Development of a krypton-doped gas symmetry capsule platform for x-ray spectroscopy of implosion cores on the NIF
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Michael Rosenberg, Arthur Pak, H. Chen, Howard A. Scott, Brian Spears, Ryan Nora, Hyun-Kyung Chung, Hong Sio, M. A. Barrios, B. A. Hammel, Leonard Jarrott, L. F. Berzak Hopkins, Shahab Khan, Brandon Lahmann, P. K. Patel, Susan Regan, Tammy Ma, C. R. Weber, Daniel Casey, and Marilyn Schneider
- Subjects
X-ray spectroscopy ,Materials science ,Krypton ,Implosion ,chemistry.chemical_element ,01 natural sciences ,010305 fluids & plasmas ,chemistry ,0103 physical sciences ,Plasma diagnostics ,Emission spectrum ,Atomic physics ,010306 general physics ,National Ignition Facility ,Spectroscopy ,Instrumentation ,Inertial confinement fusion - Abstract
The electron temperature at stagnation of an ICF implosion can be measured from the emission spectrum of high-energy x-rays that pass through the cold material surrounding the hot stagnating core. Here we describe a platform developed on the National Ignition Facility where trace levels of a mid-Z dopant (krypton) are added to the fuel gas of a symcap (symmetry surrogate) implosion to allow for the use of x-ray spectroscopy of the krypton line emission.
- Published
- 2016
46. Spectroscopic studies of hard x-ray free-electron laser-heated foils at 10 16 Wcm -2 irradiances
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D. Milathianaki, S. M. Vinko, P. Audebert, F. Deneuville, David Fritz, Ronnie Shepherd, Marta Fajardo, O. Ciricosta, Maxence Gauthier, Garth J. Williams, J. Park, Hyun-Kyung Chung, A. B. Steel, James Dunn, Alexander Graf, Justin Wark, Stephen J. Moon, C. Fourment, Hyesog Lee, Anna Lévy, Julien Fuchs, Richard W. Lee, Marco Cammarata, Jérôme Gaudin, and Bob Nagler
- Subjects
Physics ,Spectrometer ,business.industry ,Free-electron laser ,chemistry.chemical_element ,Warm dense matter ,Laser ,Linear particle accelerator ,law.invention ,Optics ,chemistry ,Beamline ,law ,Beryllium ,Atomic physics ,business ,Beam (structure) - Abstract
We report a recent experiment where the first hard x-ray beam line, X-ray Pump Probe (XPP) instrument using the SLAC National Accelerator Laboratory's Linac Coherent Light Source (LCLS) free electron laser, was used to heat thin foils to high energy densities ∼ 107 J/cm 3. An intense 9 keV, 60 fs (FWHM) duration beam with energy of 2 - 4 mJ at the XPP beam line was focused using beryllium lenses to an irradiance approaching 1016 Wcm -2. Targets of 0.5 - 3.5 μm thick foils of Ag and Cu were studied using a suite of diagnostics including Fourier Domain Interferometry, energy calorimetry and grating and crystal spectrometers. The experimental details and spectroscopic results from the campaign will be described. Preliminary results indicate that the target is heated relatively uniformly to a temperature lower than 20 eV. © 2011 SPIE.
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- 2016
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47. High energy density science with FELs, intense short pulse tunable X-ray sources
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S. J. Rose, Hyun-Kyung Chung, Siegfried Glenzer, Gianluca Gregori, Richard W. Lee, R. C. Cauble, Otto Landen, Howard A. Scott, David Riley, and Stephen J. Moon
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Physics ,Brightness ,Photon ,business.industry ,Optical engineering ,Free-electron laser ,Optical communication ,Plasma ,Warm dense matter ,Laser ,law.invention ,Optics ,law ,Optoelectronics ,business - Abstract
Short pulse (< 100 fs) tunable X-ray and VUV laser sources, based on the free electron laser (FEL) concept, will be a watershed for high energy density research in several areas. These new 4th generation light sources will have extremely high fields and short wavelength (~0.1 nm) with peak spectral brightness -photons/(s/mrad2/mm2/0.1% bandwidth- 1010 greater than 3rd generation light sources. We briefly discuss several applications: the creation of warm dense matter (WDM), probing of near solid density plasmas, and laser-plasma spectroscopy of ions in plasmas. The study of dense plasmas has been severely hampered by the fact that laser-based probes that can directly access the matter in this regime have been unavailable and these new 4th generation sources will remove these restrictions. Finally, we present the plans for a user-oriented set of facilities that will incorporate high-energy, intense short-pulse, and x-ray lasers at the first x-ray FEL, the LCLS to be opened at SLAC in 2009.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
- Published
- 2016
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48. Resonant Kα spectroscopy of solid-density aluminum plasmas
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O. Ciricosta, P.A. Heimann, Libor Juha, Jaromír Chalupský, K. Engelhorn, Tomáš Burian, D. S. Rackstraw, Justin Wark, Diling Zhu, Joshua J. Turner, Hyun-Kyung Chung, C. R. D. Brown, Benny Wu, Sven Toleikis, A. Scherz, Ulf Zastrau, Roger Falcone, Byoung-ick Cho, L. Vysin, William F. Schlotter, Andrew Higginbotham, Nina Rohringer, Catherine Graves, Tianhan Wang, M. Messersmidt, R W Lee, H. J. Lee, Věra Hájková, Bob Nagler, Sam Vinko, C. D. Murphy, Jacek Krzywinski, and Yuan Ping
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Free electron model ,Physics ,Photon ,Astrophysics::High Energy Astrophysical Phenomena ,General Physics and Astronomy ,Electron ,Ion ,Atom ,ddc:550 ,Production (computer science) ,Absorption (logic) ,Atomic physics ,Spectroscopy - Abstract
Physical review letters 109, 245003 (2012). doi:10.1103/PhysRevLett.109.245003, Published by APS, College Park, Md.
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- 2016
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49. Detailed model for hot-dense aluminum plasmas generated by an X-ray free electron laser
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C. Jackson, Sam Vinko, Justin Wark, Hyun-Kyung Chung, Richard W. Lee, T. R. Preston, O. Ciricosta, and D. S. Rackstraw
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Physics ,Electron density ,Isochoric process ,Plasma ,Condensed Matter Physics ,01 natural sciences ,010305 fluids & plasmas ,Degree of ionization ,Ionization ,0103 physical sciences ,Plasma diagnostics ,Emission spectrum ,Atomic physics ,Ionization energy ,010306 general physics - Abstract
The possibility of creating hot-dense plasma samples by isochoric heating of solid targets with high-intensity femtosecond X-ray lasers has opened up new opportunities in the experimental study of such systems. A study of the X-ray spectra emitted from solid density plasmas has provided significant insight into the X-ray absorption mechanisms, subsequent target heating, and the conditions of temperature, electron density, and ionization stages produced (Vinko et al., Nature 482, 59–62 (2012)). Furthermore, detailed analysis of the spectra has provided new information on the degree of ionization potential depression in these strongly coupled plasmas (Ciricosta et al., Phys. Rev. Lett. 109, 065002 (2012)). Excellent agreement between experimental and simulated spectra has been obtained, but a full outline of the procedure by which this has been achieved has yet to be documented. We present here the details and approximations concerning the modelling of the experiment described in the above referenced work. We show that it is crucial to take into account the spatial and temporal gradients in simulating the overall emission spectra, and discuss how aspects of the model used affect the interpretation of the data in terms of charge-resolved measurements of the ionization potential depression.
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- 2016
50. Measurement of carbon ionization balance in high-temperature plasma mixtures by temporally resolved X-ray scattering
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Otto Landen, Christoph Niemann, Gianluca Gregori, Bastian Holst, Susan Regan, Nathan Meezan, Richard W. Lee, Hiroshi Sawada, Ronald Redmer, Hyun-Kyung Chung, Dustin Froula, John Moody, and Siegfried Glenzer
- Subjects
Radiation ,Materials science ,Scattering ,Impurity ,Ionization ,Radiation hydrodynamics ,X-ray ,Plasma ,Graphite ,Atomic physics ,Spectroscopy ,Atomic and Molecular Physics, and Optics ,Spectral line - Abstract
We have measured carbon ionization balance in a multi-component plasma in the high-temperature, up to fully ionized, regime by spectrally resolved X-ray scattering. In particular, the measurements have been performed in an underdense ( n e ≈ 10 21 cm - 3 ) 0.35- μ m laser-produced plasma, containing a mixture of C, H with Al and Ar impurities, by using time-resolved back-scattered spectra from a 9.0 keV Zn He- α X-ray probe detected with a high-efficiency graphite Bragg crystal coupled to a framing camera. Measured values for the plasma temperature and carbon ionization state as well as impurity concentrations were obtained by fitting the Doppler-broadened and Compton-shifted scattered spectra at various times after the plasma heating with a modified X-ray form factor that includes the full effects of cross-correlation between different species. These data test collisional-radiative and radiation hydrodynamics modeling from cold ( T e ≲ 5 eV) to fully ionized carbon ( T e ∼ 280 eV).
- Published
- 2016
- Full Text
- View/download PDF
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