JAXA multimode thruster tops 110mN/kW in krypton test

(SpaceEnergy) JAXA researchers have demonstrated a multimode krypton thruster producing more than 110mN/kW, potentially combining high-specific-impulse electric propulsion and higher-thrust manoeuvring in one propulsion device.

The Multimode Acceleration Coaxial, or MAC, thruster integrates a nozzled hollow cathode into a Hall thruster, allowing Hall, gas-jet and combined operating modes using shared components and propellant. The researchers are targeting applications including in-space servicing, assembly and manufacturing.

Tests of a breadboard model at JAXA's Sagamihara Campus used a vacuum facility providing 220,000 litres/s effective krypton pumping speed, 20 times that of earlier experiments.

In Hall mode, the system produced 1,200-1,800 seconds specific impulse and 40-55mN/kW across a 600-1,400W power range. Simultaneously operating the Hall thruster and gas jet produced more thrust than the measured sum of the two modes individually.

The combined mode exceeded 110mN/kW around the 1kW level using krypton, which the researchers said is expected to improve the manoeuvrability of small all-electric satellites.

The team cautioned that the chamber pressure remained substantially above true orbital conditions. On-orbit experiments will therefore be needed to establish whether the measured performance synergy persists in space.

The research was funded by Japan's Acquisition, Technology & Logistics Agency under its Innovative Science and Technology Initiative for Security.