This article presents the results of a study into the new concept of the microcathode arc thruster; a thruster with an ablative anode (AA-μCAT). Such a thruster uses a triggerless discharge initiation, and has a coaxial electrode configuration where the central miniature anode is made of an ablative material (brass, solder, copper, etc), and an outer annular cathode, with optional magnetic coil. We show that the use of an ablative material (brass) increases the ion-to-arc current ratio from ∼2 to ∼4% without any focusing magnetic field, and up to 7% with a magnetic field of 0.33 T, compared with the case where the central anode is made of nonablative stainless steel, for the same pulsing power circuitry and parameters. For the first time, we demonstrate that even without a magnetic field, the AA-μCAT has a higher thrust (7 μN) and a higher thrust-to-power ratio (5.5 μN W −1 ) with respect to the thruster with a nonablative refractory stainless steel anode (5.5 μN and 4.8 μN W −1 , respectively). This fact is direct evidence of possible improvements to the microcathode arc thruster thrust-to-power ratio due to anode ablation.
With over 272 attempted launches since 2000, CubeSat technology has exponentially increased as industries and universities have realized their potential. While this growth looks promising for space research possibilities, there are still a number of issues, with the largest being CubeSat maneuverability. The majority of CubeSats cannot orient or propel themselves, meaning mission functionality is limited and collision probability will increase as time goes on. CubeSat technology has been improving, and the mission of this technology has become increasingly more important in the development and advancement of new technologies. The Micro-propulsion and Nanotechnology Laboratory at The George Washington University has constructed a four-channel Micro-Cathode Arc Thruster (μCAT) micro-propulsion subsystem that allows these satellites to perform missions without reliance on their launch vehicles. The propulsion system has a volume of approximately 541 cm 3 that can produce specific impulse values up to 3000 s. Each μCAT onboard is used for the CubeSat's attitude control, orbit change, de-orbiting, and movement. The μCAT system was integrated into the USNA's 1.5U CubeSat (BRICSat-P) to be used to perform three maneuvers while at an orbit of 500 km: de-tumbling, spin, and a delta-V that will attempt to change the orbit of the CubeSat relative to the orientation of Earth's magnetic field. The objective of this paper is to provide an overview of the thruster subsystem's development and application for the BRICSat-P mission parameters. In addition, the μCAT subsystem's circuitry, thruster head design, and development will be reviewed to provide the information used to reach CubeSat flight standards.
Presented is the ablative anode microcathode arc thruster AAμCAT. The AAμCAT is a new concept that comes from the microcathode arc thruster μCAT, which implements the idea that an ablative anode can significantly improve the thrust-to-power ratio as a result of additional utilization of electron current flowing to and ablating the anode. Three versions of the AAμCAT were analyzed, and the results were presented and compared to the standard μCAT. Total ion current, ion velocity, and erosion rate measurement experiments were performed to characterize the thrusters. For the ion current evaluation, each combination was tested with three annular permanent magnets of differing strengths: 0.1, 0.143, and 0.3 T. All three thrusters achieved approximately 36% cathodic jet transport efficiency when equipped with the 0.1 T magnet. The result of the ion velocity testing showed that each system achieved similar ion velocities (10-13 km∕s). The goal of this exercise was to determine if having an ablative anode, in addition to cathodic ablation, would increase ion current and velocity, therefore increasing specific impulse and thrust in comparison with the standard μCAT. From the experiments presented in this paper, this was found to be true.
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