Calibrated Scintillator Probe for Determining Energy Distribution, Density, and Mean Energy of the Electronic Component of a Pyrotron Plasma

Abstract

A method of determining some of the characteristics of a deuterium plasma generated and confined in a magnetic-mirror machine is described. In this case the electronic component of the plasma is characterized by a mean energy considerably greater than the ionic component. The mirror configuration readily allows detection of the flux of particles which escape through the mirror loss cone from the plasma confined between the mirrors. Scintillator probes placed near a mirror and outside the confinement region do not interfere with the confined plasma. By the use of thin aluminum absorbers placed in front of the scintillator, a determination was made of the energy distribution of the electron flux as a function of time during the decay of the pulsed mirror field. Such measurements were used to infer plasma conditions by consideration of the processes resulting in the leakage of plasma particles through the mirror. In determining the density of the plasma, the correction to be made to the integral of electron flux over time is based on conclusions as to plasma stability and the known decay rate of the pulsed magnetic field.