Effects of Radial Transport on Potential Formation and Mode Transition in a Tandem Mirror

Abstract

Effects of radial transport on potential formation in the plug cell of a tandem mirror are studied. The radial transport equation including a mobility for potential-trapped electrons in the plug cell is solved numerically in the steady state. It is shown that radial particle diffusion-losses enhance the confining potential for plug-cell electrons, of which magnitude is obtained as a function of radial diffusion-loss time for different values of the mobility and for different profiles of the potential. It is also found that a hysteresis arises in the relation between the potential and the radial diffusion-loss time, which causes a mode transition.