A two-stage μCAT-MPD thruster: toward millinewton thrust

Abstract

We discuss our efforts aimed at simultaneous improvement of the levels of thrust, thrust-to-power ratio (TPR) and efficiency of the two-stage micro-cathode arc thruster with magneto-plasma-dynamical second stage (μCAT-MPD). Such efforts include planar construction of the first stage (μCAT) with tightly-pressed ring anode and central disc cathode, enhanced hardness and durability of the inter-electrode dielectric gap provided by deposited boron-copper thin film, refractory (Mo) second-stage electrode, higher and stabilized second-stage voltage, and improved thermal isolation of the permanent magnet from the discharge area. Aforementioned features allowed achieve the average thrust of milli-newton range – up to 1.7 ± 0.3 mN, together with high TPR of 37 μN/W and efficiency of 50%, remaining low mass (~ 100 g) and low consuming power (~ 50 W) of the thruster.