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14 results on '"Impurity density"'

1. Statistical Properties of Aerosol Density in Turbulent Flows.

Author

Gribova, E. Z.

Abstract

Density fluctuations of a clot of aerosol particles in the atmosphere are studied. A one-dimensional case is considered characteristic of the motion of particles in a narrow vertical fire column or in an aircraft trail. The effect of localization of clots is shown to be observed under certain conditions, which consists in the formation of compact areas of high density of aerosol particles surrounded by areas of low density. Knowledge of such properties of impurity density can be useful in solving inverse problems of aerosol optics. [ABSTRACT FROM AUTHOR]

Published
2022
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2. 土中水膜厚度变化规律及未冻水含量预测方法.

Author

万旭升, 颜梦宇, 路建国, and 晏忠瑞

Abstract

Copyright of Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2022
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4. Effect of impurities in vacuum vessels on the plasma parameters in inductive discharges.

Author

Kim, Young-Gi, Yeom, H.J., Kwon, Deuk-Chul, Kim, Kwan-Yong, Chae, Gwang-Seok, Yoon, Jung-Sik, Kim, Jung-Hyung, and Lee, Hyo-Chang

Subjects
*CONTROLLED fusion, *ELECTRON density, *PLASMA density, *PLASMA-wall interactions, *PLASMA stability
Abstract

The mechanisms affecting plasma by external and internal inputs must be understood for both semiconductor processing and controlled nuclear fusion, which require stable and steady-state plasmas. Among various factors that can change the state of plasma, detecting and controlling the plasma–wall interactions inside the reactor are challenging. In particular, although water is a commonly encountered impurity in most vacuum systems including process chambers, studies on the direct evidence of water effect on plasma are limited. Herein, we show that there is a clear negative correlation between the impurity density and the plasma density. A small change in water impurity could cause an immediate change in the plasma density because impurities contribute to increasing the total energy loss in the steady-state plasma sustainment. To observe the impurity effect distinctly, we conducted experiments under various conditions to analyze the effect of vessel impurities on plasma parameters, such as applied power, wall contamination, and wall materials. In the experiments, it is found that the plasma density is significantly influenced by the impurity density. The results were compared with the global model calculation and they are in agreement on the relative change of the electron density. • Influence of impurity on inductively coupled plasma is analyzed. • Introduction of impurities with high rate constants decreases the electron density. • Simulation shows 0.1% H 2 O/Ar flowrate ratio lowers electron density by 74%. • Discharge cleaning effectively reduces impurity content in the vacuum vessel. • Impurity content in the vessel depends on wall material characteristics. [ABSTRACT FROM AUTHOR]

Published
2023
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8. Evaluation of impurity densities from charge exchange recombination spectroscopy measurements at ASDEX Upgrade

Author

Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear, EUROfusion Consortium, McDermott, R. M., Dux, R., Pütterich, T., Geiger, B., Kappatou, A., Lebschy, A., Bruhn, C., Cavedon, M., Frank, A., Harder, N. den, Viezzer, Eleonora, Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear, EUROfusion Consortium, McDermott, R. M., Dux, R., Pütterich, T., Geiger, B., Kappatou, A., Lebschy, A., Bruhn, C., Cavedon, M., Frank, A., Harder, N. den, and Viezzer, Eleonora

Abstract

At ASDEX upgrade (AUG) a new framework for the evaluation of impurity densities based on measurements from charge exchange recombination spectroscopy (CXRS) diagnostics has been developed. The charge exchange impurity concentration analysis code, or CHICA, can perform these calculations for all of the beam-based CXRS diagnostics at AUG and is equipped with the atomic data for all of the regularly measured charge exchange spectral lines (He, Li, B, C, N, O, and Ne). CHICA includes four different methods for the evaluation of the neutral density populations, which feature different implementations and contain varying levels of sophistication. These methods have been thoroughly benchmarked against one another, enabling the important processes for the evaluation of neutral densities to be identified as well as the neutral populations that are most critical to the accurate interpretation of the measured CXRS intensities. For the AUG neutral beams, charge exchange with the ground state of the first energy component is typically the dominant contribution to the measured CXRS intensities, but emission from reactions with the n = 2 beam halo population can contribute up to 35% to the total signal and must be included in the analysis. Neglect of this population leads to incorrect magnitudes and incorrect profile shapes of the calculated impurity density profiles. The edge lines of sight (LOS) of the core CXRS diagnostics at AUG intersect the edge pedestal inside of the neutral beam volume. Therefore, the impurity density is not constant along the LOS, complicating the interpretation of the measured intensities. Within CHICA a forward model for the edge impurity densities has been implemented, enabling the reconstruction of accurate edge profiles.

Published
2018

9. Evaluation of impurity densities from charge exchange recombination spectroscopy measurements at ASDEX Upgrade

Author

Asdex Upgrade Team, T, Mcdermott, R, Dux, R, Putterich, T, Geiger, B, Kappatou, A, Lebschy, A, Bruhn, C, Cavedon, M, Frank, A, Harder, N, Viezzer, E, Asdex Upgrade Team T., McDermott R. M., Dux R., Putterich T., Geiger B., Kappatou A., Lebschy A., Bruhn C., Cavedon M., Frank A., Harder N. D., Viezzer E., Asdex Upgrade Team, T, Mcdermott, R, Dux, R, Putterich, T, Geiger, B, Kappatou, A, Lebschy, A, Bruhn, C, Cavedon, M, Frank, A, Harder, N, Viezzer, E, Asdex Upgrade Team T., McDermott R. M., Dux R., Putterich T., Geiger B., Kappatou A., Lebschy A., Bruhn C., Cavedon M., Frank A., Harder N. D., and Viezzer E.

Abstract

At ASDEX upgrade (AUG) a new framework for the evaluation of impurity densities based on measurements from charge exchange recombination spectroscopy (CXRS) diagnostics has been developed. The charge exchange impurity concentration analysis code, or CHICA, can perform these calculations for all of the beam-based CXRS diagnostics at AUG and is equipped with the atomic data for all of the regularly measured charge exchange spectral lines (He, Li, B, C, N, O, and Ne). CHICA includes four different methods for the evaluation of the neutral density populations, which feature different implementations and contain varying levels of sophistication. These methods have been thoroughly benchmarked against one another, enabling the important processes for the evaluation of neutral densities to be identified as well as the neutral populations that are most critical to the accurate interpretation of the measured CXRS intensities. For the AUG neutral beams, charge exchange with the ground state of the first energy component is typically the dominant contribution to the measured CXRS intensities, but emission from reactions with the n = 2 beam halo population can contribute up to 35% to the total signal and must be included in the analysis. Neglect of this population leads to incorrect magnitudes and incorrect profile shapes of the calculated impurity density profiles. The edge lines of sight (LOS) of the core CXRS diagnostics at AUG intersect the edge pedestal inside of the neutral beam volume. Therefore, the impurity density is not constant along the LOS, complicating the interpretation of the measured intensities. Within CHICA a forward model for the edge impurity densities has been implemented, enabling the reconstruction of accurate edge profiles.

Published
2018

10. Calculation of impurity density and electron-spin relaxation times in p-type GaAs:Mn.

Author

Burobina, Veronika

Subjects
*ELECTRON relaxation time, *MAGNETIC semiconductors, *RELAXATION for health, *MAGNETIC moments, *ELECTRON spin, *AUDITING standards
Abstract

• Electron-spin relaxation times in 3D and 2D p-type GaAs were discussed. • Concentrations of deep and show impurities were calculated for prolonged electron spin relaxation times. • The concentration of shallow donors needs to exceed the concentration of the shallow acceptor. • The maximum spin relaxation times for the 2D and 3D materials are 77 ns and 154 ns, respectively. Magnetic semiconductors have aroused interest due to their various functionalities related to spintronic devices. Manganese (Mn) as a substitutional impurity in A 3 B 5 semiconductors supplies not only holes, but also localized spins. The ejection of Mn atoms with an uncompensated magnetic moment leads to the appearance of ferromagnetic properties. The most suitable material characterized by long-term spin dynamics is n-type GaAs. In p-type GaAs, the spin relaxation time of electrons is generally much shorter. For purposes of this research, electron-spin relaxation times in 3D and 2D p-type GaAs were studied. Calculation of impurity densities and charge state of magnetic acceptors demonstrate the essential composition of the material. Comparison of theoretical and experimental data in optical-spin orientation of electrons reveal the longest spin relaxation time of 77 ns in 2D GaAs:Mn, less than twice the best time in the p-type 3D GaAs material. [ABSTRACT FROM AUTHOR]

Published
2020
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12. Evaluation of impurity densities from charge exchange recombination spectroscopy measurements at ASDEX Upgrade

Author

Asdex Upgrade Team T., McDermott R. M., Dux R., Putterich T., Geiger B., Kappatou A., Lebschy A., Bruhn C., Cavedon M., Frank A., Harder N. D., Viezzer E., Universidad de Sevilla. Departamento de Física Atómica, Molecular y Nuclear, EUROfusion Consortium, Asdex Upgrade Team, T, Mcdermott, R, Dux, R, Putterich, T, Geiger, B, Kappatou, A, Lebschy, A, Bruhn, C, Cavedon, M, Frank, A, Harder, N, Viezzer, E, and ASDEX Upgrade Team, Max Planck Institute for Plasma Physics, Max Planck Society

Subjects
Tokamak, Population, impurity density, 01 natural sciences, Spectral line, 010305 fluids & plasmas, law.invention, ASDEX Upgrade, neutral beam attenuation, Impurity, law, 0103 physical sciences, 010306 general physics, education, Spectroscopy, tokamak, Impurity transport, Physics, education.field_of_study, Neutral beam attenuation, Impurity density, Change exchange recombination spectroscopy, Condensed Matter Physics, ddc, impurity transport, Nuclear Energy and Engineering, charge exchange recombination spectroscopy, Atomic physics, Ground state, Beam (structure)
Abstract

At ASDEX upgrade (AUG) a new framework for the evaluation of impurity densities based on measurements from charge exchange recombination spectroscopy (CXRS) diagnostics has been developed. The charge exchange impurity concentration analysis code, or CHICA, can perform these calculations for all of the beam-based CXRS diagnostics at AUG and is equipped with the atomic data for all of the regularly measured charge exchange spectral lines (He, Li, B, C, N, O, and Ne). CHICA includes four different methods for the evaluation of the neutral density populations, which feature different implementations and contain varying levels of sophistication. These methods have been thoroughly benchmarked against one another, enabling the important processes for the evaluation of neutral densities to be identified as well as the neutral populations that are most critical to the accurate interpretation of the measured CXRS intensities. For the AUG neutral beams, charge exchange with the ground state of the first energy component is typically the dominant contribution to the measured CXRS intensities, but emission from reactions with the n = 2 beam halo population can contribute up to 35% to the total signal and must be included in the analysis. Neglect of this population leads to incorrect magnitudes and incorrect profile shapes of the calculated impurity density profiles. The edge lines of sight (LOS) of the core CXRS diagnostics at AUG intersect the edge pedestal inside of the neutral beam volume. Therefore, the impurity density is not constant along the LOS, complicating the interpretation of the measured intensities. Within CHICA a forward model for the edge impurity densities has been implemented, enabling the reconstruction of accurate edge profiles. EUROfusion Consortium 633053

Published
2018

13. Electrical properties of poly(ethylene glycol dimethacrylate-n-vinyl imidazole)/single walled carbon nanotubes/n-Si schottky diodes formed by surface polymerization of single walled carbon nanotubes

Author

Ali Kara, Hakan Kockar, Nalan Tekin, M. Ahmetoglu, Saadet Kayiran Beyaz, Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü., Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü., Ahmetoğlu, Muhitdin, Kara, Ali, AAG-6271-2019, and Fen Edebiyat Fakültesi

Subjects
Semiconducting silicon compounds, Barrier heights, Electrical measurement, Schottky diodes, Leakage currents, law.invention, Polymerization, chemistry.chemical_compound, Single walled carbon nanotube, law, Impurity, Capacitance voltage characteristic, Single-walled carbon, Materials Chemistry, Imidazole, Semiconductor diodes, Electrical measurements, Physics, condensed matter, Composite material, Capacitance voltage measurements, Physics, applied, Physics, Metals and Alloys, Impurity density, Surfaces and Interfaces, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Schottky barriers, Materials science, multidisciplinary, Current voltage characteristics, Schottky Diodes, Thermionic Emission, Interface States, Cvd method, Materials science, coatings & films, Current voltage, Ideality factors, Silicon, Materials science, Schottky barrier, Surface polymerization, Capacitance, Carbon nanotube, Ethylene, Ethylene glycol, Room temperature, Single-walled carbon nanotubes (swcn), Electrical characteristic, N-vinyl imidazole, Schottky diode, Diodes, Carbon, Reverse-bias, chemistry, Chemical engineering, Semiconducting silicon, Bias voltage, Schottky barrier diodes, Adsorption, Metal semiconductor-structure
Abstract

Köçkar, Hakan (Balikesir Author), In this paper we report the electrical characteristics of the Schottky diodes formed by surface polymerization of the Poly(ethylene glycol dimethanylate-n-vinyl imidazole)/Single Walled Carbon Nanotubes on n-Si The Single Walled Carbon Nanotubes were synthesized by CVD method. The main electrical properties of the Poly(ethylene glycol dimethanylate-n-vinyl imidazole)/Single Walled Carbon Nanotubes/n-Si have been investigated through the barrier heights, the ideality factors and the impurity density distribution, by using current-voltage and reverse bias capacitance voltage characteristics. Electrical measurements were carried out at room temperature. Poly(ethylene glycol dimethacrylate-n-vinyl imidazole)/Single Walled Carbon Nanotubes/n-Si Schottky diode current-voltage characteristics display low reverse-bias leakage currents and average barrier heights of 0.61 +/- 0.02 eV and 0.72 +/- 0.02 eV obtained from both current-voltage and capacitance-voltage measurements at room temperature, respectively.

Published
2012

14. Poloidal asymmetries due to ion cyclotron resonance heating

Author

Kazakov, Ye O., Pusztai, I., Fülöp, T., Johnson, Thomas, Kazakov, Ye O., Pusztai, I., Fülöp, T., and Johnson, Thomas

Abstract

The poloidal density asymmetry of impurity ions in ion cyclotron resonance heated (ICRH) discharges is calculated. The link between the asymmetry strength and ICRH and plasma parameters is quantified. The main parameter governing the asymmetry strength is identified to be the minority ion temperature anisotropy. Through numerical simulations with the full-wave TORIC code coupled to the Fokker-Planck quasilinear solver SSFPQL, the dependence of the anisotropy on various parameters, such as ICRH power, background density and temperature, minority and impurity concentration and toroidal wavenumber has been investigated. An approximate expression for the poloidal asymmetry of impurities as a function of plasma parameters, resonance location and ICRH power is given. A quantification of the link of the impurity asymmetry and ICRH heating is valuable not only for understanding the changes in the cross-field transport but also for the possibilities to use the asymmetry measurements as diagnostics., QC 20121029

Published
2012
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