Effect of pressure profile on stochasticity of magnetic field in a conventional stellarator

In this study, the stochastization of the magnetic field in a simplified stellarator, which has a strong magnetic shear in the peripheral region, is studied using a nonlinear 3D equilibrium calculation code, HINT, which calculates the nonlinear resistive steady state using the relaxation method with...

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Bibliographic Details
Published in:Plasma physics and controlled fusion 2020-10, Vol.62 (10), p.104001
Main Author: Suzuki, Yasuhiro
Format: Article
Language:English
Subjects:
3D equilibrium
equilibrium beta limit
non-linear 3D equilibrium response
stochasticity of magnetic field
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Summary:In this study, the stochastization of the magnetic field in a simplified stellarator, which has a strong magnetic shear in the peripheral region, is studied using a nonlinear 3D equilibrium calculation code, HINT, which calculates the nonlinear resistive steady state using the relaxation method without the assumption of nested flux surfaces. For the finite beta equilibrium, the pressure-induced perturbed field breaks the nested flux surfaces, and the stochastization of the magnetic field appears in the region of the strong magnetic shear. The stochastization penetrates into the plasma core due to the increased beta and the effective plasma confinement degrades; in other words, the effective plasma volume shrinks. The stochastization strongly depends on the profile shape of the plasma pressure. Since the pressure gradient drives the Pfirsch-Schlüter current, the pressure profile affects the stochastization of the magnetic field. In order to understand the equilibrium beta limit due to the stochastization of the magnetic field, the profile shape of the plasma pressure is an important factor.
ISSN:0741-3335
1361-6587
DOI:10.1088/1361-6587/ab9a13