Utilizing RF Electric Field for Injection-Trapping High Energy Molecular Ions in Mirror Field, (I)

Abstract

A method of using rf electric field in a device for high-energy InJection is described, and the behavior of the molecular ions injected into a system combining rf and DC magnetic fields is investigated by calculation and observation.In this method, some of the injected molecular ions are decelerated by the rf field, and trapped in a small region between the mirror fields, where they are dissociated by collision with the background gas or with the plasma particles, and are thus trapped in the form of atomic ion. The relation between the rf frequency ro and the Larmor frequencies !J.Hi, !J.Hi is given by ro=N/2· !J.Hi =N/4· 0Hi. where N is the number of rf electrodes. The number N is chosen so that N/2 is an integer and N/4 a non-integer.Calculation shows that the ions injected in a certain favorable phase are stably decelerated despite their initially possessing a precessional motion. This is proven by observation of actual electron behavior.