Development of a Gridded Energy Analyzer for Measurement of the Mochi Experiment Ion Energy Distribution

Abstract

A new experiment at the University of Washington called Mochi is intended to simulate astrophysical jets in the laboratory and investigate their stability, with particular interest in conservation of canonical helicity. As a new experiment, Mochi’s plasma parameters are relatively unknown. This thesis describes the development of a gridded energy analyzer (GEA), the ultimate goal of which is to provide initial measurements of Mochi’s ion energy distribution. The concept of the Mochi.GEA is to start with the simplest possible design and make necessary improvements based on observed performance. The initial design suffered from a space charge limitation issue, which was mitigated using a pinhole aperture. Secondary electron emission was also identified as a major issue and addressed with a secondary electron suppressor. The analyzer has successfully measured the electron energy distribution but not yet successfully measured the ion energy distribution. However, the Mochi.GEA design is easily modifiable, and further development may arrive at a working design.