Charge Exchange Loss of High Temperature Plasma Confined by Mirror Magnetic Field

Abstract

Relaxation of the distribution function of ions confined in a mirror field is in investigated theoretically taking both the charge exchange and scattering effects into account. The result is compared with experiment.
If the particles are not thermalized sufficiently, the ion density decays exponentially due to the charge exchange, but only linearly due to the mirror loss. The life time, τ_cx, is proportional to the ion velocity while that of the mirror loss, τ_m, is proportional to it to the power three.
The experiment is performed on the HX-0 device, a mirror machine for high temperature experiments. A decay time of 26 μs is obtained for high energy protons which are trapped in the mirror magnetic field at the background pressure of 10⁻⁵mm Hg.