Publication

Drift Stabilisation of Ballooning Modes in an Inward-Shifted LHD Configuration

Wilfred Anthony Cooper
2010
Conference Papers

Abstract

A drift-magnetohydrodynamic theory is applied to a background anisotropic pressure equilibrium state to generate a drift corrected ballooning mode equation. The ratio of the mode frequency to the hot particle drift frequency constitutes the critical expansion parameter. The fast particles thus contribute weakly to the instability driving mechanism and also to the diamagnetic drift stabilisation. This equation is used to model the inward-shifted Large Helical Device (LHD) configuration. In the single-fluid limit, a weakly ballooning unstable band that encompasses a third of the plasma volume develops in the core of the plasma at low that becomes displaced towards the edge of the plasma at the experimentally achieved similar or equal to 5%. Finite diamagnetic drifts (mainly due to the thermal ions) effectively stabilise these ballooning structures at all values of . The validity of the large hot particle drift approximation is verified for hot to thermal ion density ratios that remain smaller than 2%. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

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https://infoscience.epfl.ch/entities/publication/69e6ffa1-5a36-41c4-85e9-10bab15571e7

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Wilfred Anthony Cooper
2010
Conference Papers

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/69e6ffa1-5a36-41c4-85e9-10bab15571e7

About this result

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The stability of a plasma is an important consideration in the study of plasma physics. When a system containing a plasma is at equilibrium, it is possible for certain parts of the plasma to be disturbed by small perturbative forces acting on it. The stability of the system determines if the perturbations will grow, oscillate, or be damped out. In many cases, a plasma can be treated as a fluid and its stability analyzed with magnetohydrodynamics (MHD).

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Drift Stabilisation of Ballooning Modes in an Inward-Shifted LHD Configuration

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