Langmuir probe diagnostics of the exhaust plume of a miniature DC-discharge plasma-thruster

Abstract

This study is concerned with the design and construction of a com- puterised measurement acquisition system to be applied to the problem of diagnosing the exhaust plume of a U-shaped miniature DC-discharge micro-thruster. The system includes the design and construction of Lang- muir probes in various sizes and the design and construction of a position- ing bench for the Langmuir probes which can be used inside of the vacuum chamber of the plasma propulsion laboratory wherein the probe measure- ments will take place. The collective measurement acquisition system is designed to automatically conduct a survey or collection of probe mea- surements whilst producing data reports and computationally applying the Langmuir method to each IV curve found and for each speci ed point in the exhaust plume. Pro le plots are produced for each measurement parameter. The system and its components were also tested with a con- tained plasma using specially constructed discharge tubes. The associated software and robotics collectively aim to eliminate any need for tedious and time consuming manual measurements and seek to reduce human er- ror. These tools will be used by the plasma propulsion laboratory to aid in future studies and designs of DC-discharge micro-thrusters. Due to a relocation of the laboratory, time constraints prevented tests of the probe mechanism on actual micro-thruster systems