11 results on '"Sips, George"'
Search Results
2. The role of JET for the preparation of the ITER exploitation
- Author
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Romanelli, Francesco, Laxåback, Martin, Durodié, Frédéric, Horton, Lorne, Lehnen, Michael, Murari, Andrea, Rimini, Fernanda, Sips, George, and Zastrow, Klaus-Dieter
- Published
- 2011
- Full Text
- View/download PDF
3. Modelling of combined ICRF and NBI heating in JET hybrid plasmas
- Author
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Gallart Dani, Mantsinen Mervi, Challis Clive, Frigione Domenico, Graves Jonathan, Hobirk Joerg, Belonohy Eva, Czarnecka Agata, Eriksson Jacob, Goniche Marc, Hellesen Carl, Jacquet Philippe, Joffrin Emmanuel, Krawczyk Natalia, King Damian, Lennholm Morten, Lerche Ernesto, Pawelec Ewa, Sips George, Solano Emilia, Tsalas Maximos, and Valisa Marco
- Subjects
Physics ,QC1-999 - Abstract
During the 2015-2016 JET campaigns many efforts have been devoted to the exploration of high performance plasma scenarios envisaged for ITER operation. In this paper we model the combined ICRF+NBI heating in selected key hybrid discharges using PION. The antenna frequency was tuned to match the cyclotron frequency of minority hydrogen (H) at the center of the tokamak coinciding with the second harmonic cyclotron resonance of deuterium. The modelling takes into account the synergy between ICRF and NBI heating through the second harmonic cyclotron resonance of deuterium beam ions which allows us to assess its impact on the neutron rate RNT. We evaluate the influence of H concentration which was varied in different discharges in order to test their role in the heating performance. According to our modelling, the ICRF enhancement of RNT increases by decreasing the H concentration which increases the ICRF power absorbed by deuterons. We find that in the recent hybrid discharges this ICRF enhancement was in the range of 10-25%. Finally, we extrapolate the results to D-T and find that the best performing hybrid discharges correspond to an equivalent fusion power of ∼7.0 MW in D-T.
- Published
- 2017
- Full Text
- View/download PDF
4. The Role of Combined ICRF and NBI Heating in JET Hybrid Plasmas in Quest for High D-T Fusion Yield
- Author
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Mantsinen Mervi, Challis Clive, Frigione Domenico, Graves Jonathan, Hobirk Joerg, Belonohy Eva, Czarnecka Agata, Eriksson Jacob, Gallart Dani, Goniche Marc, Hellesen Carl, Jacquet Philippe, Joffrin Emmanuel, King Damian, Krawczyk Natalia, Lennholm Morten, Lerche Ernesto, Pawelec Ewa, Sips George, Solano Emilia R., Tsalas Maximos, and Valisa Marco
- Subjects
Physics ,QC1-999 - Abstract
Combined ICRF and NBI heating played a key role in achieving the world-record fusion yield in the first deuterium-tritium campaign at the JET tokamak in 1997. The current plans for JET include new experiments with deuterium-tritium (D-T) plasmas with more ITER-like conditions given the recently installed ITER-like wall (ILW). In the 2015-2016 campaigns, significant efforts have been devoted to the development of high-performance plasma scenarios compatible with ILW in preparation of the forthcoming D-T campaign. Good progress was made in both the inductive (baseline) and the hybrid scenario: a new record JET ILW fusion yield with a significantly extended duration of the high-performance phase was achieved. This paper reports on the progress with the hybrid scenario which is a candidate for ITER longpulse operation (∼1000 s) thanks to its improved normalized confinement, reduced plasma current and higher plasma beta with respect to the ITER reference baseline scenario. The combined NBI+ICRF power in the hybrid scenario was increased to 33 MW and the record fusion yield, averaged over 100 ms, to 2.9x1016 neutrons/s from the 2014 ILW fusion record of 2.3x1016 neutrons/s. Impurity control with ICRF waves was one of the key means for extending the duration of the high-performance phase. The main results are reviewed covering both key core and edge plasma issues.
- Published
- 2017
- Full Text
- View/download PDF
5. Progress and first results with the new multifrequency ECRH system for ASDEX upgrade
- Author
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Wagner, Dietmar H., Stober, Jorg Karl, Leuterer, Fritz, Sips, George, Grunwald, Gerhard, Monaco, Francesco, Munich, Max J., Poli, Emanuele, Schutz, Harald, Volpe, Francesco, Treutterer, Wolfgang, Zohm, Hartmut, Franke, Thomas, Thumm, Manfred, Heidinger, Roland, Gantenbein, Gerd, Meier, Andreas, Kasparek, Walter, Lechte, Carsten, Litvak, Alexander G., Denisov, Gregory G., Chirkov, Alexei, Tai, Evgeny, Popov, Leonid, Nichiporenko, Vadim, Myasnikov, Vadim, Solyanova, Elena, and Malygin, Sergey
- Subjects
Electron paramagnetic resonance -- Analysis ,Business ,Chemistry ,Electronics ,Electronics and electrical industries - Abstract
A multifrequency electron cyclotron resonance heating (ECRH) system is currently under construction at the ASDEX Upgrade tokamak experiment. The system employs depressed collector gyrotrons, step tunable in the range of 105-140 GHz, with a maximum output power of 1 MW and a pulse length of 10 s. One two-frequency GYCOM gyrotron has been in routine operation at ASDEX Upgrade since 2006. A further extension of the system with three more gyrotrons is underway. An in situ calibration scheme for the broadband torus window has been developed. The system is equipped with fast steerable mirrors for real-time MHD control. The gyrotron and the mirrors are fully integrated into the discharge control system. The ECRH system turned out to be essential for the operation of H-modes after covering the plasma facing components of ASDEX Upgrade with tungsten. Deposition of ECRH inside [[rho].sub.tor] < 0.2 is necessary to prevent accumulation of W in plasmas with high pedestal temperatures. With respect to the limited loop voltage available in ITER, the use of ECRH for neutral-gas preionization to facilitate plasma breakdown and its application during the current ramp-up to increase the conductivity in order to save transformer flux have been demonstrated successfully for 105 GHz, 3.2 T (O1-mode) and 140 GHz, 2.2 T (X2-mode), corresponding to 170 GHz at ITER with the full and half values of its foreseen toroidal field of 5.3 T. Index Terms--Electron cyclotron resonance heating (ECRH), fast steerable launcher, step-tunable Gyrotron.
- Published
- 2009
6. Norovirus outbreak in a natural playground: A One Health
- Author
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Sips, George, Dirven, MJG, Donkervoort, JT, van Kolfschoten, FM, Schapendonk, Claudia, Phan, Vu, Bloem, Annemieke, Leeuwen, AF, Trompenaars, MCE, Koopmans, Marion, Baltissen - van der Eijk, Annemiek, de Graaf, Miranda, Fanoy, E B, Medical Microbiology & Infectious Diseases, and Virology
- Subjects
fluids and secretions ,SDG 3 - Good Health and Well-being ,virus diseases - Abstract
Norovirus constitutes the most frequently identified infectious cause of disease outbreaks associated with untreated recreational water. When investigating outbreaks related to surface water, a One Health approach is insightful. Historically, there has been a focus on potential contamination of recreational water by bird droppings and a recent publication demonstrating human noroviruses in bird faeces suggested this should be investigated in future water-related norovirus outbreaks. Here, we describe a One Health approach investigating a norovirus outbreak in a natural playground. On social media, a large amount of waterfowl were reported to defecate near these playground premises leading to speculations about their potential involvement. Surface water, as well as human and bird faecal specimens, was tested for human noroviruses. Norovirus was found to be the most likely cause of the outbreak but there was no evidence for transmission via waterfowl. Cases had become known on social media prior to notification to the public health service underscoring the potential of online media as an early warning system. In view of known risk factors, advice was given for future outbreak investigations and natural playground design.
- Published
- 2020
7. Een norovirusuitbraak in een natuurspeeltuin: een One-Health-benadering
- Author
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Sips, George, Dirven, MJG, Donkervoort, FM, Schapendonk, Claudia, Phan, Vu, Bloem, Annemieke, Leeuwen, AF, Trompenaars, M, Koopmans, Marion, Baltissen - van der Eijk, Annemiek, de Graaf, Miranda, Fanoy, E B, Medical Microbiology & Infectious Diseases, and Virology
- Published
- 2019
8. Viral neuroinvasion:causes, mechanisms and potential consequences
- Author
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Sips, George, Sips, George, Sips, George, and Sips, George
- Abstract
Meer inzicht in ontstaan virale ziekten van het centrale zenuwstelsel Over het ontstaan van ernstige neurologische ziekten zoals de ziekte van Alzheimer, Multiple Sclerose (MS) en de ziekte van Parkinson, is nog veel onduidelijk. Wel vermoeden wetenschappers dat er een verband zou kunnen bestaan tussen virale infecties en de ontwikkeling van deze chronische neurologische ziekten. George Sips onderzocht in zijn proefschrift de oorzaken, mechanismen en mogelijke gevolgen van virale infecties van het centrale zenuwstelsel. Deze inzichten kunnen in de toekomst helpen om behandelingen ‘op maat’ te ontwikkelen., The origin and pathogenesis of severe neurological diseases such as Alzheimer’s disease, Multiple Sclerosis and Parkinson’s disease remain largely unclear. Scientists suspect that there may be causal associations between viral infections and the development of these chronic neurological disorders. George Sips, in his thesis, examined the causes, mechanisms and potential consequences of viral infections of the central nervous system. These insights may aid the future development of “personalized” treatments.
- Published
- 2014
9. The Role of Combined ICRF and NBI Heating in JET Hybrid Plasmas in Quest for High D-T Fusion Yield
- Author
-
Barcelona Supercomputing Center, Mantsinen, Mervi, Challis, Clive, Frigione, Domenico, Graves, Jonathan, Hobirk, Joerg, Belonohy, Eva, Czarnecka, Agata, Eriksson, Jacob, Gallart, Dani, Goniche, Marc, Hellesen, Carl, Jacquet, Philippe, Joffrin, Emmanuel, King, Damian, Krawczyk, Natalia, Lennholm, Morten, Lerche, Ernesto, Pawelec, Ewa, Sips, George, Solano, Emilia R., Tsalas, Maximos, Valisa, Marco, JET Contributors, Barcelona Supercomputing Center, Mantsinen, Mervi, Challis, Clive, Frigione, Domenico, Graves, Jonathan, Hobirk, Joerg, Belonohy, Eva, Czarnecka, Agata, Eriksson, Jacob, Gallart, Dani, Goniche, Marc, Hellesen, Carl, Jacquet, Philippe, Joffrin, Emmanuel, King, Damian, Krawczyk, Natalia, Lennholm, Morten, Lerche, Ernesto, Pawelec, Ewa, Sips, George, Solano, Emilia R., Tsalas, Maximos, Valisa, Marco, and JET Contributors
- Abstract
Combined ICRF and NBI heating played a key role in achieving the world-record fusion yield in the first deuterium-tritium campaign at the JET tokamak in 1997. The current plans for JET include new experiments with deuterium-tritium (D-T) plasmas with more ITER-like conditions given the recently installed ITER-like wall (ILW). In the 2015-2016 campaigns, significant efforts have been devoted to the development of high-performance plasma scenarios compatible with ILW in preparation of the forthcoming D-T campaign. Good progress was made in both the inductive (baseline) and the hybrid scenario: a new record JET ILW fusion yield with a significantly extended duration of the high-performance phase was achieved. This paper reports on the progress with the hybrid scenario which is a candidate for ITER longpulse operation (∼1000 s) thanks to its improved normalized confinement, reduced plasma current and higher plasma beta with respect to the ITER reference baseline scenario. The combined NBI+ICRF power in the hybrid scenario was increased to 33 MW and the record fusion yield, averaged over 100 ms, to 2.9x1016 neutrons/s from the 2014 ILW fusion record of 2.3x1016 neutrons/s. Impurity control with ICRF waves was one of the key means for extending the duration of the high-performance phase. The main results are reviewed covering both key core and edge plasma issues., This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission., Peer Reviewed, Postprint (published version)
- Published
- 2017
10. Modelling of combined ICRF and NBI heating in JET hybrid plasmas
- Author
-
Barcelona Supercomputing Center, Gallart, Dani, Mantsinen, Mervi, Challis, Clive, Frigione, Domenico, Graves, Jonathan, Hobirk, Joerg, Belonohy, Eva, Czarnecka, Agata, Eriksson, Jacob, Goniche, Marc, Hellesen, Carl, Jacquet, Philippe, Joffrin, Emmanuel, Krawczyk, Natalia, King, Damian, Lennholm, Morten, Lerche, Ernesto, Pawelec, Ewa, Sips, George, Solano, Emilia, Tsalas, Maximos, Valisa, Marco, JET Contributors, Barcelona Supercomputing Center, Gallart, Dani, Mantsinen, Mervi, Challis, Clive, Frigione, Domenico, Graves, Jonathan, Hobirk, Joerg, Belonohy, Eva, Czarnecka, Agata, Eriksson, Jacob, Goniche, Marc, Hellesen, Carl, Jacquet, Philippe, Joffrin, Emmanuel, Krawczyk, Natalia, King, Damian, Lennholm, Morten, Lerche, Ernesto, Pawelec, Ewa, Sips, George, Solano, Emilia, Tsalas, Maximos, Valisa, Marco, and JET Contributors
- Abstract
During the 2015-2016 JET campaigns many efforts have been devoted to the exploration of high performance plasma scenarios envisaged for ITER operation. In this paper we model the combined ICRF+NBI heating in selected key hybrid discharges using PION. The antenna frequency was tuned to match the cyclotron frequency of minority hydrogen (H) at the center of the tokamak coinciding with the second harmonic cyclotron resonance of deuterium. The modelling takes into account the synergy between ICRF and NBI heating through the second harmonic cyclotron resonance of deuterium beam ions which allows us to assess its impact on the neutron rate RNT. We evaluate the influence of H concentration which was varied in different discharges in order to test their role in the heating performance. According to our modelling, the ICRF enhancement of RNT increases by decreasing the H concentration which increases the ICRF power absorbed by deuterons. We find that in the recent hybrid discharges this ICRF enhancement was in the range of 10-25%. Finally, we extrapolate the results to D-T and find that the best performing hybrid discharges correspond to an equivalent fusion power of ∼7.0 MW in D-T., This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014-2018 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission. Dani Gallart would like to thank “La Caixa” for support of his PhD studies., Peer Reviewed, Postprint (published version)
- Published
- 2017
11. Viral neuroinvasion: causes, mechanisms and potential consequences
- Author
-
Sips, George and Wilschut, Jan
- Abstract
Meer inzicht in ontstaan virale ziekten van het centrale zenuwstelsel Over het ontstaan van ernstige neurologische ziekten zoals de ziekte van Alzheimer, Multiple Sclerose (MS) en de ziekte van Parkinson, is nog veel onduidelijk. Wel vermoeden wetenschappers dat er een verband zou kunnen bestaan tussen virale infecties en de ontwikkeling van deze chronische neurologische ziekten. George Sips onderzocht in zijn proefschrift de oorzaken, mechanismen en mogelijke gevolgen van virale infecties van het centrale zenuwstelsel. Deze inzichten kunnen in de toekomst helpen om behandelingen ‘op maat’ te ontwikkelen.
- Published
- 2014
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