Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Idomura, Yasuhiro; Nakata, Motoki; Jolliet, S.*
Plasma and Fusion Research (Internet), 9(Sp.2), p.3503028_1 - 3503028_7, 2014/04
Full-f gyrokinetic simulations compute both turbulent transport and profile formations under fixed power, momentum, and particle input as in experiments. This approach has the capability of dictating plasma profiles, provided that time scale of the simulation is long enough to establish power, momentum, and particle balance conditions. Recent Peta-scale supercomputers made such long time scale simulations feasible, and full-f gyrokinetic simulations are applied to reactor relevant numerical experiments. In this paper, physical models, numerical approaches, and accuracy issues of the gyrokinetic full-f Eulerian code GT5D are summarized, and then, its recent applications to the scaling studies of turbulent transport with respect to plasma size and heating power are reviewed.
Jolliet, S.; McMillan, B. F.*; Villard, L.*; Vernay, T.*; Angelino, P.*; Tran, T. M.*; Brunner, S.*; Bottino, A.*; Idomura, Yasuhiro
Journal of Computational Physics, 231(3), p.745 - 758, 2012/02
Times Cited Count:14 Percentile:61.76(Computer Science, Interdisciplinary Applications)Jolliet, S.; Idomura, Yasuhiro
Nuclear Fusion, 52(2), p.023026_1 - 023026_14, 2012/02
Idomura, Yasuhiro; Jolliet, S.*
Proceedings of International Conference for High Performance Computing, Networking, Storage and Analysis (SC '11) (USB Flash Drive), 9 Pages, 2011/11
Plasma turbulence simulations based on the five dimensional (5D) gyrokinetic equation, which is the first principle model of fusion plasmas, are standard tools in analyzing turbulent transport phenomena. However, 5D turbulence simulations at the ITER size requires extreme scale computation, and therefore, an efficient use of massively parallel computers has been an important issue in computational fusion science. In GT5D, which is a 5D Eulerian code developed by JAEA, 5D phase space is parallelized using multi-dimensional domain decomposition based on physical symmetry properties of the equation system. By implementing this parallel model on a multilayer network consisting of multiple MPI communicators and a SMP layer, the scalability is highly improved, and the sustained performance of Tflops is achieved on 16384 cores of BX900.
Idomura, Yasuhiro; Jolliet, S.
Progress in Nuclear Science and Technology (Internet), 2, p.620 - 627, 2011/10
Jolliet, S.; Idomura, Yasuhiro
Progress in Nuclear Science and Technology (Internet), 2, p.85 - 89, 2011/10
Camenen, Y.*; Idomura, Yasuhiro; Jolliet, S.; Peeters, A. G.*
Nuclear Fusion, 51(7), p.073039_1 - 073039_11, 2011/07
Times Cited Count:93 Percentile:96.13(Physics, Fluids & Plasmas)Idomura, Yasuhiro; Jolliet, S.; Yoshida, Maiko; Urano, Hajime
Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03
An impact of the toroidal rotation and the safety factor q on the ion temperature gradient driven (ITG) turbulence is studied using a global gyrokinetic toroidal full-f five dimensional Euleriancode GT5D. In the rotation scan numerical experiments, the radial electric field Er profile is changed depending on the toroidal rotation. Although local transport levels are affected by the Er profile, global transport properties are not changed, when the magnitudes of its shearing rate are in similar levels on average. In the q scan numerical experiments, turbulent transport is significantly enhanced at higher q. It is found that the stabilizing effect of Er shear on liner ITG modes becomes less effective at higher q. Both the ion heat transport and the non-diffusive momentum transport are enhanced. The former leads to lower ion temperature gradient, while the latter produces larger inward momentum flux and co-current spontaneous rotation in the plasma core.
Labit, B.*; Pochelon, A.*; Rancic, M.*; Piras, F.*; Bencze, A.*; Bottino, A.*; Brunner, S.*; Camenen, Y.*; Chattopadhyay, P. K.*; Coda, S.*; et al.
Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 8 Pages, 2011/03
Jolliet, S.*; Idomura, Yasuhiro
Nuclear Fusion, 52(2), p.023026_1 - 023026_14, 2011/02
Times Cited Count:41 Percentile:84.20(Physics, Fluids & Plasmas)Villard, L.*; Bottino, A.*; Brunner, S.*; Casati, A.*; Chowdhury, J.*; Dannert, T.*; Ganesh, R.*; Garbet, X.*; Grler, T.*; Grandgirard, V.*; et al.
Plasma Physics and Controlled Fusion, 52(12), p.124038_1 - 124038_18, 2010/11
Times Cited Count:21 Percentile:60.74(Physics, Fluids & Plasmas)McMillan, B. F.*; Lapillonne, X.*; Brunner, S.*; Villard, L.*; Jolliet, S.; Bottino, A.*; Grler, T.*; Jenko, F.*
Physical Review Letters, 105(15), p.155001_1 - 155001_4, 2010/10
Times Cited Count:108 Percentile:93.64(Physics, Multidisciplinary)Bottino, A.*; Scott, B. D.*; Brunner, S.*; McMillan, B. F.*; Tran, T. M.*; Vernay, T.*; Villard, L.*; Jolliet, S.; Hatzky, R.*; Peeters, A. G.*
IEEE Transactions on Plasma Science, 38(9), p.2129 - 2135, 2010/09
Times Cited Count:26 Percentile:67.96(Physics, Fluids & Plasmas)Jolliet, S.*; Bottino, A.*; Angelino, P.*; Hatzky, R.*; Tran, T. M.*; McMillan, B. F.*; Sauter, O.*; Appert, K.*; Idomura, Yasuhiro; Villard, L.*
Computer Physics Communications, 177(5), p.409 - 425, 2007/09
Times Cited Count:192 Percentile:98.52(Computer Science, Interdisciplinary Applications)A global plasma turbulence simulation code, ORB5, is presented. A particular feature is the use of straight-field-line magnetic coordinates and a field-aligned Fourier filtering technique that dramatically improves the performance of the code in terms of both the numerical noise reduction and the maximum time step allowed. Another feature is the capability to treat arbitrary axisymmetric ideal MHD equilibrium configurations. The code is validated against an analytical theory of zonal flows and against other codes for a selection of linear and nonlinear tests.
Bottino, A.*; Angelino, P.*; Allfrey, S. J.*; Brunner, S.*; Hatzky, R.*; Idomura, Yasuhiro; Jolliet, S.*; Sauter, O.*; Tran, T. M.*; Villard, L.*
Theory of Fusion Plasmas, ISPP21, p.75 - 86, 2004/00
The global nonlinear electrostatic PIC code ORB5 solves the gyrokinetic Vlasov-Poisson system assuming adiabatic electrons in realistic tokamak magnetohydrodynamic (MHD) equilibria. The present version of ORB5 shows remarkable particle and energy conservation properties and can be used for physics studies in toroidal geometry. In particular, the optimized tracer loading method has been adapted to tokamak geometry and implemented in ORB5 together with a new adaptive gyro-average algorithm. Basic physical conservation properties (energy and particle number) are used as indicators of the quality of the numerical simulations. In this paper we present the first nonlinear results of electrostatic collisionless microinstabilities of realistic MHD shaped equilibria, provided by the MHD equilibrium code CHEASE, including the toroidicity induced geometrical coupling of the zonal ExB flow and the parallel velocity nonlinearlity.
Jolliet, S.*; Angelino, P.*; Bottino, A.*; Idomura, Yasuhiro; Villard, L.*
Theory of Fusion Plasmas, ISPP21, p.345 - 351, 2004/00
Global particle-in-cell (PIC) simulations are a very useful tool for studying the time evolution of turbulence induced by ion-temperature-gradient (ITG) instabilities. Unfortunately, the linear code LORB5 and its non-linear version ORB5 require high computational power. In order to study more sophisticated models, we need to optimize these codes. We will focus on LORB5, which uses a cylindrical grid (r,z) for solving the Vlasov equation and a (s,) grid for the Poisson equation. The approach presented in this work consists of implementing the gyrokinetic model using a single (s,
) grid. Here
is the straight-field-line poloidal coordinate. A method to avoid the singularity at the magnetic axis is presented, and a benchmark with the CYCLONE case is shown.
Idomura, Yasuhiro; Jolliet, S.
no journal, ,
Plasma turbulence simulations based on the five dimensional (5D) gyrokinetic equation, which is the first principle model of fusion plasmas, is a standard approach in studying turbulent transport phenomena in fusion plasmas. However, an application of such 5D turbulence simulations to realistic machine sizes requires huge computational resources, and therefore, an efficient use of massively parallel computers has been an important issue in computational fusion science. In this work, a 5D mesh code GT5D is ported on six advanced massively parallel platforms and comprehensive benchmark tests are performed. By using a hybrid parallelization technique based on physical properties of the gyrokinetic equation, the scalability of the code is improved beyond cores with multi-core processors. Through comparisons of performances on the six platforms, the dependency of processing performances on processor architectures and issues in improving communication performances are clarified.
Idomura, Yasuhiro; Jolliet, S.
no journal, ,
Plasma turbulence simulations based on the five dimensional (5D) gyrokinetic equation, which is the first principle model of fusion plasmas, is a standard approach in studying turbulent transport phenomena in fusion plasmas. However, an application of such 5D turbulence simulations to realistic machine sizes requires huge computational resources, and therefore, an efficient use of massively parallel computers has been an important issue in computational fusion science. In this work, multilayer parallelization techniques on a gyrokinetic 5D mesh code GT5D are discussed. In GT5D, a 5D phase space is parallelized using a multi-dimensional domain decomposition based on physical properties and symmetries of the equation system. By implementing this parallelization techniques with a multilayer network consisting of multiple MPI communicators and SMP, the scalability is highly improved, and the sustained performance of TFlops is achieved on 16384 cores of BX900.
Jolliet, S.*; Idomura, Yasuhiro
no journal, ,