Containment of plasma in a trap with combined magnetic field

The containing properties of an adiabatic trap with a magnetic field increasing in the longitudinal and radial directions are investigated. This field is obtained from a combination of the ordinary mirror field configuration (main field H0) and the field of a system of current-carrying conductors laid parallel to the axis of the trap (stabilizing field H). The conductors are placed uniformly in azimuth around the side walls. The trap is filled with plasma of density n10⁹–10¹⁰ cm^–3 and proton energy T_i5eV (T_e20 eV). The plasma lifetime is measured as a function of H. and the neutral gas pressure. From the results obtained, it is concluded that such combined fields ensure stable containment of the plasma, unbroken by magnetohydrodynamic instabilities at any rate for = nI/(H²/8) 10^–4]. The stabilization of the instability is confirmed by analysis of the plasma oscillations for various values of H. The disintegration of the plasma is determined by the charge exchange of fast ions in the residual gas; the maximum containment time which can be achieved is 0.06 sec for p = 7.10^–9mmHg. A qualitative picture of the plasma density over the radius of the trap is obtained.Translated from Atomnaya Énergiya, Vol. 17, No. 5, pp. 366–375, November, 1964