Initial Characterization of the EEDF of an ECR-based Plasma Cathode Operating on Molecular Gases

Electron cyclotron resonance (ECR) plasma cathodes utilize RHCP wave heating in a magnetic field to ionize a neutral gas. The extraction of electrons from this device is dependent on the ratio of charged-particle collecting areas; therefore, the source region (where the ionizations occur) is biased negatively to collect ions, while the electrons are collected at a downstream anode. This work seeks to characterize and evaluate the performance of ECR plasma cathodes on molecular gasses, for purposes such as in-situ utilization. Previous experimental testing with this configuration has identified the presence of an electron beam escaping downstream of the anode, representing a collection loss in the device. The goal of this work is therefore to first characterize the energy distribution of this escaping electron beam, and then to identify ways to control this EEDF to reduce beam loss in the device, thereby increasing extracted current and device efficiency.