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Xu S, Maeyama S, Watanabe TH, Gürcan ÖD. Reversal of the Parallel Drift Frequency in Anomalous Transport of Impurity Ions. PHYSICAL REVIEW LETTERS 2024; 132:105101. [PMID: 38518327 DOI: 10.1103/physrevlett.132.105101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 02/02/2024] [Indexed: 03/24/2024]
Abstract
It is found that, in the studies of heavy ion transport with gyrokinetic simulations, the ion parallel drift frequency can reverse sign in velocity space when the amplitude variation of the electrostatic potential fluctuation is strong along the magnetic field line. As a result, the particle transport related to the parallel dynamics is strongly enhanced. It is noted that, while parallel gradient of the fluctuation amplitude can be instigated by a large magnetic shear or safety factor in a tokamak, the generic mechanism is independent of its cause, which suggests broader applications to kinetic plasma problems. Some relevant topics are briefly addressed in the end.
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Affiliation(s)
- Shaokang Xu
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
- Nagoya University, Furo-cho, Nagoya 464-8602, Japan
| | - S Maeyama
- Nagoya University, Furo-cho, Nagoya 464-8602, Japan
- National Institute for Fusion Science, Toki, Gifu 509-5292, Japan
| | - T-H Watanabe
- Nagoya University, Furo-cho, Nagoya 464-8602, Japan
| | - Ö D Gürcan
- Laboratoire de Physique des Plasmas, CNRS, Ecole Polytechnique, Sorbonne Université, Université Paris-Saclay, Observatoire de Paris, F-91120 Palaiseau, France
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2
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Pak C, Billings V, Schlitters M, Bergeson SD, Murillo MS. Preliminary study of plasma modes and electron-ion collisions in partially magnetized strongly coupled plasmas. Phys Rev E 2024; 109:015201. [PMID: 38366520 DOI: 10.1103/physreve.109.015201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Accepted: 12/07/2023] [Indexed: 02/18/2024]
Abstract
Magnetic fields influence ion transport in plasmas. Straightforward comparisons of experimental measurements with plasma theories are complicated when the plasma is inhomogeneous, far from equilibrium, or characterized by strong gradients. To better understand ion transport in a partially magnetized system, we study the hydrodynamic velocity and temperature evolution in an ultracold neutral plasma at intermediate values of the magnetic field. We observe a transverse, radial breathing mode that does not couple to the longitudinal velocity. The inhomogeneous density distribution gives rise to a shear velocity gradient that appears to be only weakly damped. This mode is excited by ion oscillations originating in the wings of the distribution where the plasma becomes non-neutral. The ion temperature shows evidence of an enhanced electron-ion collision rate in the presence of the magnetic field. Ultracold neutral plasmas provide a rich system for studying mode excitation and decay.
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Affiliation(s)
- Chanhyun Pak
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - Virginia Billings
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - Matthew Schlitters
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - Scott D Bergeson
- Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
| | - Michael S Murillo
- Department of Computational Mathematics, Science and Engineering, Michigan State University, East Lansing, Michigan 48824, USA
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3
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Sabot R, Hennequin P, Colas L. Fluctuation Measurements and Their Link with Transport on Tore Supra. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst09-a9176] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- R. Sabot
- CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
| | - P. Hennequin
- Laboratoire de Physique des Plasmas, CNRS, Ecole Polytechnique, 91128 Palaiseau, France
| | - L. Colas
- CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
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4
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Waltz RE. Rho-Star Scaling and Physically Realistic Gyrokinetic Simulations of Transport in DIII-D. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst05-a1059] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- R. E. Waltz
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
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5
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Hoang GT. Key Role of the Current Density Profile on Core Confinement and Transport in Tore Supra Plasmas: Electron Heat and Particle Transport. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst09-a9185] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- G. T. Hoang
- CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
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6
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Bucalossi J. Problems and Issues for Tokamak Long-Pulse Operation: Major Progress on Tore Supra. FUSION SCIENCE AND TECHNOLOGY 2017. [DOI: 10.13182/fst04-a554] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Jérôme Bucalossi
- Euratom-CEA Association CEA0DSM0DRFC, CEA Cadarache, 13108 St-Paul-Lez-Durance, France
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7
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Sierchio JM, Cziegler I, Terry JL, White AE, Zweben SJ. Comparison of velocimetry techniques for turbulent structures in gas-puff imaging data. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:023502. [PMID: 26931844 DOI: 10.1063/1.4939672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Recent analysis of Gas Puff Imaging (GPI) data from Alcator C-Mod found blob velocities with a modified tracking time delay estimation (TDE). These results disagree with velocity analysis performed using direct Fourier methods. In this paper, the two analysis methods are compared. The implementations of these methods are explained, and direct comparisons using the same GPI data sets are presented to highlight the discrepancies in measured velocities. In order to understand the discrepancies, we present a code that generates synthetic sequences of images that mimic features of the experimental GPI images, with user-specified input values for structure (blob) size and velocity. This allows quantitative comparison of the TDE and Fourier analysis methods, which reveals their strengths and weaknesses. We found that the methods agree for structures of any size as long as all structures move at the same velocity and disagree when there is significant nonlinear dispersion or when structures appear to move in opposite directions. Direct Fourier methods used to extract poloidal velocities give incorrect results when there is a significant radial velocity component and are subject to the barber pole effect. Tracking TDE techniques give incorrect velocity measurements when there are features moving at significantly different speeds or in different directions within the same field of view. Finally, we discuss the limitations and appropriate use of each of methods and applications to the relationship between blob size and velocity.
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Affiliation(s)
- J M Sierchio
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - I Cziegler
- Center for Momentum Transport and Flow Organization, University of California, San Diego, La Jolla, California 92093, USA
| | - J L Terry
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - A E White
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - S J Zweben
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
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8
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Liu P, Deng Z, Yang L, Zhan M, Wang X. Network approach to the pinning control of drift-wave turbulence. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 89:062918. [PMID: 25019862 DOI: 10.1103/physreve.89.062918] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Indexed: 06/03/2023]
Abstract
Network of coupled oscillators has long been employed as an important approach to explore the complicated dynamics in spatially extended systems. Here we show how this approach can be used to the analysis of turbulence pinning control. Specifically, by use of a model of two-dimensional drift-wave plasma turbulence, we investigate how the performance of the turbulence control is influenced by the spatial distribution of the pinning strength. It is found that the dynamics of pinned turbulence can be well captured by a simple model of networked modes, based on which the dependence of the control performance on the pinning distribution can be analytically obtained. In particular, the model predicts that as the distribution of the pinning strength becomes more nonuniform, the performance of turbulence control will be gradually decreased. This theoretical prediction is in good agreement with the results of numerical simulations, including the sinusoidal and localized pinning distributions. Our studies provide a new viewpoint to the mechanism of mode couplings in drift-wave turbulence, as well as be constructive to the design of new schemes for controlling turbulence in realistic systems.
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Affiliation(s)
- Panpan Liu
- Department of Physics, Zhejiang University, Hangzhou 310027, China and School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China
| | - Zhigang Deng
- Department of Physics, Zhejiang University, Hangzhou 310027, China and School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China
| | - Lei Yang
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Meng Zhan
- Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Xingang Wang
- Department of Physics, Zhejiang University, Hangzhou 310027, China and School of Physics and Information Technology, Shaanxi Normal University, Xi'an 710062, China
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9
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Zhong WL, Zou XL, Bourdelle C, Song SD, Artaud JF, Aniel T, Duan XR. Convective velocity reversal caused by turbulence transition in tokamak plasma. PHYSICAL REVIEW LETTERS 2013; 111:265001. [PMID: 24483800 DOI: 10.1103/physrevlett.111.265001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Indexed: 06/03/2023]
Abstract
Particle transport has been studied in the Tore Supra tokamak by using modulated ion cyclotron resonance heating to generate perturbations of density and temperature. For the first time, a reversal of the particle convective velocity and a strong increase in the turbulent particle flux have been clearly observed. When the mixed critical gradient ζc=R/L(T)+4(R/L(n))=22 is exceeded, the particle flux increases sharply and the convective velocity reverses from inward to outward. These observations are in agreement with quasilinear, gyrokinetic calculations. The critical gradient corresponds to a transition from an instability driven by the ion temperature gradient to the onset of another instability caused by trapped electrons.
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Affiliation(s)
- W L Zhong
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - X L Zou
- CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
| | - C Bourdelle
- CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
| | - S D Song
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
| | - J F Artaud
- CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
| | - T Aniel
- CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
| | - X R Duan
- Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, People's Republic of China
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10
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Xiao WW, Zou XL, Ding XT, Yao LH, Feng BB, Song XM, Song SD, Zhou Y, Liu ZT, Yuan BS, Sun HJ, Ji XQ, Gao YD, Li YG, Yan LW, Yang QW, Liu Y, Dong JQ, Duan XR, Liu Y, Pan CH. Observation of a spontaneous particle-transport barrier in the HL-2A tokamak. PHYSICAL REVIEW LETTERS 2010; 104:215001. [PMID: 20867107 DOI: 10.1103/physrevlett.104.215001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2008] [Indexed: 05/29/2023]
Abstract
Using the profile analysis, the density perturbation transport analysis, and the Doppler reflectometry measurement, for the first time a spontaneous and steady-state particle-transport barrier has been evidenced in the Ohmic plasmas in the HL-2A tokamak with no externally applied momentum or particle input except the gas puffing. A threshold in density has been found for the observation of the barrier. The particle diffusivity is well-like, and the convection is found to be inward outside the well and outward inside the well. The formation of the barrier coincides with the transition between the trapped electron mode and the ion temperature gradient driven mode.
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Affiliation(s)
- W W Xiao
- Southwestern Institute of Physics, P.O. Box 432, Chengdu, China
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11
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Futatani S, Garbet X, Benkadda S, Dubuit N. Reversal of impurity pinch velocity in tokamaks plasma with a reversed magnetic shear configuration. PHYSICAL REVIEW LETTERS 2010; 104:015003. [PMID: 20366368 DOI: 10.1103/physrevlett.104.015003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2009] [Indexed: 05/29/2023]
Abstract
Impurity transport in tokamak core plasmas is investigated with a three-dimensional fluid global code. It is shown that, in the presence of an internal transport barrier (ITB) created by a reversed magnetic shear configuration, one can obtain a reversal of the impurity pinch velocity which can change from the inward direction to the outward direction. This scenario is favorable for expelling impurities from the central region and decontaminating the core plasma. The mechanism of pinch reversal is attributed to a change of direction of the curvature pinch and to a modification of the dominant underlying instability caused by a change of the gradient of the ion temperature and consequently of the ITB formation.
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Affiliation(s)
- S Futatani
- International Institute for Fusion Science, CNRS-Université de Provence, Centre de St. Jérôme, Case 321, 13397 Marseille Cedex 20, France
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12
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Angioni C, Peeters AG. Direction of impurity pinch and auxiliary heating in tokamak plasmas. PHYSICAL REVIEW LETTERS 2006; 96:095003. [PMID: 16606271 DOI: 10.1103/physrevlett.96.095003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2005] [Indexed: 05/08/2023]
Abstract
A mechanism of particle pinch for trace impurities in tokamak plasmas, arising from the effect of parallel velocity fluctuations in the presence of a turbulent electrostatic potential, is identified analytically by means of a reduced fluid model and verified numerically with a gyrokinetic code for the first time. The direction of such a pinch reverses as a function of the direction of rotation of the turbulence in agreement with the impurity pinch reversal observed in some experiments when moving from dominant auxiliary ion heating to dominant auxiliary electron heating.
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Affiliation(s)
- C Angioni
- Max-Planck-Institut für Plasmaphysik, IPP-EURATOM Association, D-85748 Garching bei München, Germany
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13
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Vlad M, Spineanu F, Benkadda S. Impurity pinch from a ratchet process. PHYSICAL REVIEW LETTERS 2006; 96:085001. [PMID: 16606191 DOI: 10.1103/physrevlett.96.085001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2005] [Indexed: 05/08/2023]
Abstract
A ratchet-type average velocity is shown to appear for test particles moving in a stochastic potential and a magnetic field that is space dependent. This is a possible explanation for impurity behavior in tokamak plasmas.
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Affiliation(s)
- M Vlad
- Association EURATOM-MEdC Romania, NILPRP, MG-36, Magurele, Bucharest, Romania.
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14
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Mantica P, Thyagaraja A, Weiland J, Hogeweij GMD, Knight PJ. Heat pinches in electron-heated Tokamak plasmas: theoretical turbulence models versus experiments. PHYSICAL REVIEW LETTERS 2005; 95:185002. [PMID: 16383908 DOI: 10.1103/physrevlett.95.185002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2005] [Indexed: 05/05/2023]
Abstract
Two fluid turbulence models, the drift wave based quasilinear 1.5D Weiland model and the electromagnetic global 3D nonlinear model CUTIE, have been used to account for heat pinch evidence in off-axis modulated electron cyclotron heating experiments in the Rijnhuizen Tokamak Project. Both models reproduce the main features indicating inward heat convection in mildly off-axis cases. In far-off-axis cases with hollow electron temperature profiles, the existence of outward convection was reproduced only by CUTIE. Turbulence mechanisms driving heat convection in the two models are discussed.
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Affiliation(s)
- P Mantica
- Istituto di Fisica del Plasma P. Caldirola, Associazione Euratom-ENEA-CNR, Milano, Italy
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15
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Hallatschek K, Dorland W. Giant electron tails and passing electron pinch effects in tokamak-core turbulence. PHYSICAL REVIEW LETTERS 2005; 95:055002. [PMID: 16090885 DOI: 10.1103/physrevlett.95.055002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2004] [Indexed: 05/03/2023]
Abstract
The anomalous particle transport in a tokamak core is believed to be linked to the advection of magnetically trapped electrons alone, owing to the passing electrons maintaining a thermal equilibrium along the field lines. Surprisingly, in nonlinear numerical studies, the radial flux of passing electrons rivals that of the trapped ones. The strong interaction of passing electrons and electric fluctuations is mediated by long tails of the modes along the magnetic field, which are generated by the passing electrons in the first place.
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Affiliation(s)
- K Hallatschek
- Centre for Interdisciplinary Plasma Science, Max-Planck Institut für Plasmaphysik, EURATOM-IPP Association, D-85748 Garching, Germany
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16
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Hoang GT, Bourdelle C, Garbet X, Artaud JF, Basiuk V, Bucalossi J, Clairet F, Fenzi-Bonizec C, Gil C, Ségui JL, Travère JM, Tsitrone E, Vermare L. Parametric dependence of turbulent particle transport in tore supra plasmas. PHYSICAL REVIEW LETTERS 2004; 93:135003. [PMID: 15524729 DOI: 10.1103/physrevlett.93.135003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2004] [Indexed: 05/24/2023]
Abstract
Steady state full noninductive current tore supra plasmas offer a unique opportunity to study the local parametric dependence of particle pinch velocity, in order to discriminate among different theories. Magnetic field shear is found to generate an inward pinch which is dominant in the gradient region (normalized radius 0.3</=r/a</=0.6). In contrast, the direction of the pinch in the plasma core (r/a</=0.3) is correlated with the electron temperature gradient length. The results are in agreement with both the turbulent theoretical and computational predictions.
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Affiliation(s)
- G T Hoang
- Euratom-CEA Association, CEA/DSM/DRFC, CEA Cadarache F-13108, Saint-Paul-Lez-Durance, France
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