Wall stabilization of the rigid ballooning m=1 mode in a long-thin mirror trap

The prospect of stabilization of the m = 1 'rigid' ballooning mode in an open axially symmetric long-thin trap with the help of a conducting lateral wall surrounding a column of isotropic plasma is studied. It was found that for effective wall stabilization, the beta parameter beta must exceed some critical value beta (crit). The dependence of beta (crit) on the mirror ratio, radial pressure profile, axial profile of the vacuum magnetic field, and the width of vacuum gap between plasma and lateral wall was studied. Minimal critical beta at the level of 70% is achieved at zero vacuum gap, although stability zone at beta -> 1 exists even at extremely wide vacuum gap. It is shown that when a conducting lateral wall is combined with conducting end plates simulating attachment of the end MHD stabilizers to the central cell of an open trap, there are two critical beta values and two stability zones that can merge, making stable the entire range of allowable beta values 0 < beta < 1.

Automated summary

This article studies the prospect of stabilizing the 'rigid' ballooning mode in a long-thin trap by using a conducting lateral wall around a column of isotropic plasma. The study finds that for effective wall stabilization, the beta parameter beta must exceed a critical value beta (crit). The dependence of beta (crit) on various factors such as mirror ratio, pressure profile, magnetic field profile, and vacuum gap width is also examined.