Thrust Measurements on the High Efficient and Reliable Vacuum Arc Thruster (HERVAT)

In this work, thrust measurements of the high efficient and reliable vacuum arc thruster (HERVAT) are performed for different pulse energies. The thruster system includes a thruster head together with a newly developed pulse processing unit (PPU). The complete system (HERVAT + PPU) is able to perform more than 1 × 107 pulses. Moreover, the influence of an integrated active magnetic nozzle is investigated. As a result, the thrust to power ratio, the average thrust level and the impulse bit for each configuration are measured and calculated. For the thrust measurements, a highly sensitive horizontal thrust balance with an active force actuator is used and operated in the thrust compensation mode. The investigated system is able to achieve levels from 5 to 40 μN and thrust to power ratios from 1 to 2 μN/W. The experimental results are compared to the data available in literature.

Characterization of Vacuum Arc Thruster Performance in Weak Magnetic Nozzle

Vacuum arc thruster performance in a magnetic nozzle configuration is experimentally characterized. Measurements are performed on a miniature coaxial thruster with an anode inner diameter of 1.8 mm. The magnetic field B is produced by a single air coil, 18 mm in diameter. Direct measurement of thrust, mass consumption and arc current are performed. To obtain statistically viable results ≈ 6000 arc pulses are analyzed at each operational point. Cathode mass erosion is measured using laser profilometry. To sustain thruster operation over several measurement cycles, an active cathode feeding system is used. For 0 < B ≤ 0.2 T, performance increase over the non-magnetic case is observed with the best thrust to arc power ratio T / P ≈ 9 μ N/W obtained at B ≈ 0.2 T. A parametric model is provided that captures the performance enhancement based on beam collimation and acceleration by the magnetic nozzle. For B > 0.2 T, the arc discharge is shown to be suppressed nullifying any additional gains by the nozzle effect.