The Experts below are selected from a list of 315 Experts worldwide ranked by ideXlab platform
T Hatae - One of the best experts on this subject based on the ideXlab platform.
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internal transport barrier on q 3 surface and poloidal plasma spin up in jt 60u high beta p discharges
Physical Review Letters, 1994Co-Authors: Y Koide, M Kikuchi, M Mori, S Tsuji, S Ishida, N Asakura, Y Kamada, T Nishitani, Y Kawano, T HataeAbstract:Spontaneous formation of an internal transport barrier was observed associated with improved confinement in the high-${\mathrm{\ensuremath{\beta}}}_{\mathit{p}}$ discharges in the JT-60U tokamak. The radial location of the transport barrier was found to be on the q=3 surface. A fast magnetohydrodynamic event localized at the transport barrier triggered the subsequent formation of an edge transport barrier that resulted in the further confinement improvement. In these discharges, a high poloidal rotation velocity that significantly exceeded the prediction of the present Neoclassical Theory was also observed at r/a=0.8.
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internal transport barrier on q 3 surface and poloidal plasma spin up in jt 60u high β p discharges
Physical Review Letters, 1994Co-Authors: Y Koide, M Kikuchi, M Mori, S Tsuji, S Ishida, N Asakura, Y Kamada, T Nishitani, Y Kawano, T HataeAbstract:Spontaneous formation of an internal transport barrier was observed associated with improved confinement in the high-${\mathrm{\ensuremath{\beta}}}_{\mathit{p}}$ discharges in the JT-60U tokamak. The radial location of the transport barrier was found to be on the q=3 surface. A fast magnetohydrodynamic event localized at the transport barrier triggered the subsequent formation of an edge transport barrier that resulted in the further confinement improvement. In these discharges, a high poloidal rotation velocity that significantly exceeded the prediction of the present Neoclassical Theory was also observed at r/a=0.8.
J L Velasco - One of the best experts on this subject based on the ideXlab platform.
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incompressibility of impurity flows in low density tj ii plasmas and comparison with Neoclassical Theory
Nuclear Fusion, 2013Co-Authors: J Arevalo, Javier Alonso, K J Mccarthy, J L VelascoAbstract:Poloidal and toroidal velocities of fully ionized carbon are measured by means of charge exchange recombination spectroscopy in the TJ-II stellarator. We present a detailed treatment of the 3D geometry and show that flow measurements, performed at different locations of the same flux surface, are compatible with flow incompressibility for the low density plasmas under study (line averaged electron densities ¯ ne 10 19 m −3 ). Furthermore, comparison with Neoclassical calculations shows quantitative agreement with the measured radial electric field and ion parallel mass flow in the absence of an external momentum input. (Some figures may appear in colour only in the online journal)
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incompressibility of impurity flows in low density tj ii plasmas and comparison with Neoclassical Theory
arXiv: Plasma Physics, 2012Co-Authors: J Arevalo, Javier Alonso, K J Mccarthy, J L VelascoAbstract:Poloidal and toroidal velocities of fully-ionised carbon are measured by means of charge exchange recombination spectroscopy (CXRS) in the TJ-II stellarator. We present a detailed treatment of the 3D geometry and show that flow measurements, performed at different locations of the same flux surface, are compatible with flow incompressibility for the low density plasmas under study (line averaged electron densities $\bar{n}_e\,\le\,10^{19}$ m$^{-3}$). Furthermore, comparison with Neoclassical calculations shows quantitative agreement with the measured radial electric field and ion bootstrap parallel flow in the absence of an external momentum input.
Javier Alonso - One of the best experts on this subject based on the ideXlab platform.
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electrostatic potential variation on the flux surface and its impact on impurity transport
Nuclear Fusion, 2017Co-Authors: J M Garciaregana, C D Beidler, P Helander, R Kleiber, A Mollen, Javier Alonso, Matt Landreman, H Maasberg, H M Smith, Y TurkinAbstract:The impurity transport in magnetically confined plasmas under some conditions finds neither quantitatively nor qualitatively a satisfactory Theory-based explanation. This compromises the successful realization of thermo-nuclear fusion for energy production since impurity accumulation is known to be one of the causes that limits the plasma performance through radiative losses and plasma dilution. Under stellarator reactor-relevant conditions, accumulation is supported by the negative (inwards pointing) radial electric field which must arise to satisfy the ambipolarity constraint on the Neoclassical particle fluxes. The high charge number of the impurities makes their transport particularly sensitive to the presence of electric fields and, consequently, the electrostatic potential variation on the flux surface, , which conventional Neoclassical Theory usually neglects, may contribute to the theoretical interpretation of experimental results not yet fully understood, e.g. Ida et al (2009 Phys. Plasmas 16 056111) and Yoshinuma et al (2009 Nucl. Fusion 49 062002). In the present work we have considered different stellarator configurations and assessed the impact that has on the radial particle transport of selected impurities. The results for LHD show that can strongly modify this transport, resulting in large deviations of the level of inward impurity flux predicted by the standard Neoclassical Theory in most cases. In Wendelstein 7-X, on the contrary, is significantly smaller and, for the parameters considered, its effect only appreciable for impurities with high charge number. Finally, in TJ-II the potential variation leads to appreciable changes of the impurity radial flux, although not to the extent its large amplitude might lead one to think. The dependence on the chosen parameters and open questions for future developments are discussed.
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incompressibility of impurity flows in low density tj ii plasmas and comparison with Neoclassical Theory
Nuclear Fusion, 2013Co-Authors: J Arevalo, Javier Alonso, K J Mccarthy, J L VelascoAbstract:Poloidal and toroidal velocities of fully ionized carbon are measured by means of charge exchange recombination spectroscopy in the TJ-II stellarator. We present a detailed treatment of the 3D geometry and show that flow measurements, performed at different locations of the same flux surface, are compatible with flow incompressibility for the low density plasmas under study (line averaged electron densities ¯ ne 10 19 m −3 ). Furthermore, comparison with Neoclassical calculations shows quantitative agreement with the measured radial electric field and ion parallel mass flow in the absence of an external momentum input. (Some figures may appear in colour only in the online journal)
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incompressibility of impurity flows in low density tj ii plasmas and comparison with Neoclassical Theory
arXiv: Plasma Physics, 2012Co-Authors: J Arevalo, Javier Alonso, K J Mccarthy, J L VelascoAbstract:Poloidal and toroidal velocities of fully-ionised carbon are measured by means of charge exchange recombination spectroscopy (CXRS) in the TJ-II stellarator. We present a detailed treatment of the 3D geometry and show that flow measurements, performed at different locations of the same flux surface, are compatible with flow incompressibility for the low density plasmas under study (line averaged electron densities $\bar{n}_e\,\le\,10^{19}$ m$^{-3}$). Furthermore, comparison with Neoclassical calculations shows quantitative agreement with the measured radial electric field and ion bootstrap parallel flow in the absence of an external momentum input.
Y Koide - One of the best experts on this subject based on the ideXlab platform.
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internal transport barrier on q 3 surface and poloidal plasma spin up in jt 60u high beta p discharges
Physical Review Letters, 1994Co-Authors: Y Koide, M Kikuchi, M Mori, S Tsuji, S Ishida, N Asakura, Y Kamada, T Nishitani, Y Kawano, T HataeAbstract:Spontaneous formation of an internal transport barrier was observed associated with improved confinement in the high-${\mathrm{\ensuremath{\beta}}}_{\mathit{p}}$ discharges in the JT-60U tokamak. The radial location of the transport barrier was found to be on the q=3 surface. A fast magnetohydrodynamic event localized at the transport barrier triggered the subsequent formation of an edge transport barrier that resulted in the further confinement improvement. In these discharges, a high poloidal rotation velocity that significantly exceeded the prediction of the present Neoclassical Theory was also observed at r/a=0.8.
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internal transport barrier on q 3 surface and poloidal plasma spin up in jt 60u high β p discharges
Physical Review Letters, 1994Co-Authors: Y Koide, M Kikuchi, M Mori, S Tsuji, S Ishida, N Asakura, Y Kamada, T Nishitani, Y Kawano, T HataeAbstract:Spontaneous formation of an internal transport barrier was observed associated with improved confinement in the high-${\mathrm{\ensuremath{\beta}}}_{\mathit{p}}$ discharges in the JT-60U tokamak. The radial location of the transport barrier was found to be on the q=3 surface. A fast magnetohydrodynamic event localized at the transport barrier triggered the subsequent formation of an edge transport barrier that resulted in the further confinement improvement. In these discharges, a high poloidal rotation velocity that significantly exceeded the prediction of the present Neoclassical Theory was also observed at r/a=0.8.
J Arevalo - One of the best experts on this subject based on the ideXlab platform.
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incompressibility of impurity flows in low density tj ii plasmas and comparison with Neoclassical Theory
Nuclear Fusion, 2013Co-Authors: J Arevalo, Javier Alonso, K J Mccarthy, J L VelascoAbstract:Poloidal and toroidal velocities of fully ionized carbon are measured by means of charge exchange recombination spectroscopy in the TJ-II stellarator. We present a detailed treatment of the 3D geometry and show that flow measurements, performed at different locations of the same flux surface, are compatible with flow incompressibility for the low density plasmas under study (line averaged electron densities ¯ ne 10 19 m −3 ). Furthermore, comparison with Neoclassical calculations shows quantitative agreement with the measured radial electric field and ion parallel mass flow in the absence of an external momentum input. (Some figures may appear in colour only in the online journal)
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incompressibility of impurity flows in low density tj ii plasmas and comparison with Neoclassical Theory
arXiv: Plasma Physics, 2012Co-Authors: J Arevalo, Javier Alonso, K J Mccarthy, J L VelascoAbstract:Poloidal and toroidal velocities of fully-ionised carbon are measured by means of charge exchange recombination spectroscopy (CXRS) in the TJ-II stellarator. We present a detailed treatment of the 3D geometry and show that flow measurements, performed at different locations of the same flux surface, are compatible with flow incompressibility for the low density plasmas under study (line averaged electron densities $\bar{n}_e\,\le\,10^{19}$ m$^{-3}$). Furthermore, comparison with Neoclassical calculations shows quantitative agreement with the measured radial electric field and ion bootstrap parallel flow in the absence of an external momentum input.
