South African National Space Agency, Hermanus, South Africa; University of the Witwatersrand, Johannesburg, South Africa; School of Mechanical, Industrial and Aeronautical Engineering, University of the Witwatersrand, Johannesburg, South Africa
Lun, J., South African National Space Agency, Hermanus, South Africa, University of the Witwatersrand, Johannesburg, South Africa; Law, C., School of Mechanical, Industrial and Aeronautical Engineering, University of the Witwatersrand, Johannesburg, South Africa
Vacuum arc thrusters (VATs) are a potentially useful technology for use as microthrusters, given their simplicity, low mass, and low-power requirements. However, further development is still needed to improve and mature their performance and operation. In an effort to improve thruster characteristics, we investigate the use of conically shaped convergent cathode surface profiles in a low-power coaxial VAT design. Experimental measurements of ion current density distribution, thrust, and erosion rate were taken for a range of cathode profiles and materials. Results show that modifying the profile of the cathode face can affect the plasma jet's plume distribution and even improve thrust production in certain cases. One likely cause of the thrust improvement is speculated to be increased charge exchange collisions resulting in a lower average ion charge state of the ejecting plasma. © 1973-2012 IEEE.