High thrust-to-power ratio micro-cathode arc thruster

Abstract

The Micro-Cathode Arc Thruster (μCAT) is an electric propulsion device that ablates solid cathode material, through an electrical vacuum arc discharge, to create plasma and ultimately produce thrust in the μN to mN range. About 90% of the arc discharge current is conducted by electrons, which go toward heating the anode and contribute very little to thrust, with only the remaining 10% going toward thrust in the form of ion current. A preliminary set of experiments were conducted to show that, at the same power level, thrust may increase by utilizing an ablative anode. It was shown that ablative anode particles were found on a collection plate, compared to no particles from a non-ablative anode, while another experiment showed an increase in ion-to-arc current by approximately 40% at low frequencies compared to the non-ablative anode. Utilizing anode ablation leads to an increase in thrust-to-power ratio in the case of the μCAT.

Space Propulsion Technology for Small Spacecraft

“…A type of Vacuum arc thruster called Micro-Cathode Arc Thruster (µCAT) of the University of Washington [78], [79] has flown on the BRICSat-P mission, a 1.5 U Cubesat launched in spring 2015, featuring 4 µCAT thruster heads. Fig.…”

Vacuum Testing of a Miniaturized Switch Mode Amplifier Powering an Electrothermal Plasma Micro-Thruster

“…Space inherently engages with a multitude of disciplines with plasma physics often playing an important role, whether directly (electric propulsion [1]) or indirectly (plasma processing of components and sensors used in the space sector [2]). There are a variety of concepts currently under development to provide propulsion for nano-satellites with some of the technology already under testing in orbit (resisto-jets, ion spray thruster, low power arcjet, hollow cathode thruster, pulsed plasma thruster [3][4][5][6][7]). A good example is the development by a university group of the micro cathodic arc jet with a recent satellite detumbling demonstration in orbit [3,7].…”

“…There are a variety of concepts currently under development to provide propulsion for nano-satellites with some of the technology already under testing in orbit (resisto-jets, ion spray thruster, low power arcjet, hollow cathode thruster, pulsed plasma thruster [3][4][5][6][7]). A good example is the development by a university group of the micro cathodic arc jet with a recent satellite detumbling demonstration in orbit [3,7]. The result of having on-board propulsion rather than only attitude determination control systems (reaction wheels, magnetorquers) would be satellites that survive longer, have a wider envelope of performance, and which can produce research data and commercial returns of greater quality and quantity, especially if formation flying and orbit maneuvers could be routinely achieved.…”

Space micropropulsion systems for Cubesats and small satellites: From proximate targets to furthermost frontiers

“…74 One of the major inefficiencies of the system is associated with the fact that only about 10% of the discharge current is the ion current, which contributes to the thrust. 20 90% of the discharge current is conducted by electrons contributing to the anode heating. By utilizing the ablative anode material (or modifying the anode geometry) so that anode ablation becomes significant, a twofold result is expected: the anode temperature will be decreased due to ablative cooling, and the anode material will be injecting, thus increasing the flow rate.…”

“…Another member of the family, the variable specific impulse magnetoplasma rocket also known as VASIMIR, 19 which employs radio waves for propellant ionization and heating and a magnetic field for its acceleration, promises to fill the niche for a system that can operate in high-thrust, low-specific impulse and low-trust, high-specific impulse modes. Other systems currently being developed include pulsed plasma thrusters, 20 magnetoplasma-dynamic thrusters, and numerous others. One of the critical challenges of electric propulsion systems lies in its dependence on the electric energy to increase the velocity of the ionized propellant, making the life-time and efficiency of the device power limited.…”