Optimization of Nonlinear Turbulence in Stellarators

Fuente: arXiv
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Autori principali: Kim, Patrick, Buller, Stefan, Conlin, Rory, Dorland, William, Dudt, Daniel W., Gaur, Rahul, Jorge, Rogerio, Kolemen, Egemen, Landreman, Matt, Mandell, Noah R., Panici, Dario
Natura: Preprint
Pubblicazione: 2023
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author Kim, Patrick
Buller, Stefan
Conlin, Rory
Dorland, William
Dudt, Daniel W.
Gaur, Rahul
Jorge, Rogerio
Kolemen, Egemen
Landreman, Matt
Mandell, Noah R.
Panici, Dario
author_facet Kim, Patrick
Buller, Stefan
Conlin, Rory
Dorland, William
Dudt, Daniel W.
Gaur, Rahul
Jorge, Rogerio
Kolemen, Egemen
Landreman, Matt
Mandell, Noah R.
Panici, Dario
contents We present new stellarator equilibria that have been optimized for reduced turbulent transport using nonlinear gyrokinetic simulations within the optimization loop. The optimization routine involves coupling the pseudo-spectral GPU-native gyrokinetic code GX with the stellarator equilibrium and optimization code DESC. Since using GX allows for fast nonlinear simulations, we directly optimize for reduced nonlinear heat fluxes. To handle the noisy heat flux traces returned by these simulations, we employ the simultaneous perturbation stochastic approximation (SPSA) method that only uses two objective function evaluations for a simple estimate of the gradient. We show several examples that optimize for both reduced heat fluxes and good quasisymmetry as a proxy for low neoclassical transport. Finally, we run full transport simulations using the T3D stellarator transport code to evaluate the changes in the macroscopic profiles.
format Preprint
id arxiv_https___arxiv_org_abs_2310_18842
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Optimization of Nonlinear Turbulence in Stellarators
Kim, Patrick
Buller, Stefan
Conlin, Rory
Dorland, William
Dudt, Daniel W.
Gaur, Rahul
Jorge, Rogerio
Kolemen, Egemen
Landreman, Matt
Mandell, Noah R.
Panici, Dario
Plasma Physics
We present new stellarator equilibria that have been optimized for reduced turbulent transport using nonlinear gyrokinetic simulations within the optimization loop. The optimization routine involves coupling the pseudo-spectral GPU-native gyrokinetic code GX with the stellarator equilibrium and optimization code DESC. Since using GX allows for fast nonlinear simulations, we directly optimize for reduced nonlinear heat fluxes. To handle the noisy heat flux traces returned by these simulations, we employ the simultaneous perturbation stochastic approximation (SPSA) method that only uses two objective function evaluations for a simple estimate of the gradient. We show several examples that optimize for both reduced heat fluxes and good quasisymmetry as a proxy for low neoclassical transport. Finally, we run full transport simulations using the T3D stellarator transport code to evaluate the changes in the macroscopic profiles.
title Optimization of Nonlinear Turbulence in Stellarators
topic Plasma Physics
url https://arxiv.org/abs/2310.18842