Measurement of Momentum and Recoil Impulse of Plasma Jet of Vacuum Arc Thruster

Abstract

To measure the mechanical momentum of a plasma jet, the deflection of a collector suspended on long threads in front of the jet was analyzed (ballistic pendulum method). Alternatively, the recoil impulse in frequency mode of arc operation was measured with a specially designed thrust balance. The dependence of the vacuum arc plasma jet momentum and recoil impulse on the arc current amplitude was studied in the current range from 10 to 800 A. The experiment shows that at a relatively low arc current ( $150~\mu \text{N}$ /A, which is consistent with the known data; with a further increase in the arc current (>100–150 A), the specific reaction force increases and can significantly exceed the above mentioned value. In addition, the specific reaction force strongly increases when the axial magnetic field is applied to the discharge cell. The experiments performed with two cathode materials are also compared. The material presented in the article is of interest for fundamental and methodological issues as well as for applications primarily to the creation and testing of vacuum arc based micro-thrusters ( $\mu $ VAT) for small/ultra-small satellites.