Formation of multi-charged ions and plasma stability at quasigasdynamic plasma confinement in a mirror magnetic trap

It is known that an increase in plasma density in sources of multicharged i ons leads to a substantial increase of ion current and slightly improves th e ion distribution over charge states. The validity of this statement was v erified in experiments with plasma densities not exceeding several units of 10(12) cm(-3). In the present work it is demonstrated experimentally that, for the electron densities exceeding 10(13) cm(-3), the regime of plasma c onfinement in a trap changes significantly and the quasigasdynamic regime o f plasma confinement is realized. Comparison of numerical simulations and e xperimental data showed the essential influence of the anisotropy of electr on velocity distribution in a plasma on the ion charge state distribution. This allows looking for the optimal conditions for the creation of highly c harged ions in plasma. In this article we also address problems of plasma s tability in an axisymmetric mirror trap under powerful microwave pumping. F irst experiments on ion extraction from a dense plasma pumped by millimeter wave radiation are described. (C) 2000 American Institute of Physics. [S00 34-6748(00)61402-8].