Experimental investigation of stability in a high energy plasma confined by a simple magnetic mirror field (MIGMA)

A plasma, formed by direct injection of 1.1 to 1.25 MeV molecular deuterium ions, was stably confined by a simple magnetic mirror field, in a device named Migma. The plasma ion number was determined by using both silicon surface barrier detectors and an RF pickup system. For the former, a Monte Carlo type simulation of the system was employed to analyze the experimental data. The two methods were found to agree at a value for the trapped ion number within the experimental error. The RF system also measured the impact parameter distribution of the trapped ions. An analytic simulation of beam-gas dissociation was found to fit the experimental data at poor vacuums (the Migma II experiments); at good vacuums (Migma III), the expermental data indicated a higher trapping rate than possible due to beam-gas collisions, and an impact parameter more highly peaked at cell center than expected. This indicates that other dissociation mechanisms were in effect, such as Lorentz and beam-plasma