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(EX/P5-12) Effect of Limiter Biasing on Plasma MHD-Stability in GDT Device

A.A. Ivanov¹⁾, P.A. Bagryansky¹⁾, A.A. Lizunov¹⁾, A.L. Solomachin²⁾, A.A. Zuev^1)
 
1) Budker Institute of Nuclear Physics, Novosibirsk, Russia
²⁾ Novosibirsk State University, Novosibirsk, Russia

Abstract.  Radial electric field can essentially alter plasma MHD-stability in a long axisymmetric mirror traps stabilized by remote MHD-anchors. In particular, estimate show that for the Gas Dynamic Trap (GDT), the radial electric field is essential comparing with magnetic field curvature effects. Influence of the radial electric field on the MHD-stability was studied in the GDT using a set of electrically biased radial limiters and segmented end walls. That provides a control of the radial profile of ambipolar potential. It was shown that biasing the peripheral end wall section to a potential of $\sim$150 V leads to considerable increase of the energy confinement time due to reduction of the electric field in the plasma volume. The MHD-stability boundary was significantly modified. Possible stabilization mechanism is considered in the paper.

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