Discharge Ignition and Lifetime Optimization in Micro-Cathode Vacuum Arc Thruster

Micro-cathode vacuum arc thrusters (μCATs) are simple and reliable propulsion engines for small satellites such as CubeSats^{1, 2}. This type of thrusters produce thrust as a result of quasi-neutral plasma jet expansion formed at the cathode. in this work, we analyzed the discharge ignition mechanism and lifetime optimization approaches, for the pulsed micro-cathode triggerless vacuum arc thruster model. To this end, a simplified model³ of the thruster consisting of two rectangular electrodes on alumina ceramic plate with interelectrode gap covered by carbon paint is considered. It is shown that after optimizing the inter-electrode gap, electrical power and the value of magnetic field, such “idealized” thruster model can provide up to 1.2-1.3 million pulses with the high degree of stability of ignition and amplitude of arc current. These findings may be used in designing of micro-cathode thrusters with the rigidly fixed, unmovable electrodes. Our results allow one to conclude that in order to provide sufficient thruster lifetime for long space missions, special attention should be given to the insulator selection and cathodic jet interaction with the insulator surface.

Micro-cathode vacuum arc thrusters (μCATs) are simple and reliable propulsion engines for small satellites such as CubeSats^{1, 2}. This type of thrusters produce thrust as a result of quasi-neutral plasma jet expansion formed at the cathode. In this work, we analyzed the discharge ignition mechanism and lifetime optimization approaches, for the pulsed micro-cathode triggerless vacuum arc thruster model. To this end, a simplified model³ of the thruster consisting of two rectangular electrodes on alumina ceramic plate with interelectrode gap covered by carbon paint is considered. It is shown that after optimizing the inter-electrode gap, electrical power and the value of magnetic field, such “idealized” thruster model can provide up to 1.2-1.3 million pulses with the high degree of stability of ignition and amplitude of arc current. These findings may be used in designing of micro-cathode thrusters with the rigidly fixed, unmovable electrodes. Our results allow one to conclude that in order to provide sufficient thruster lifetime for long space missions, special attention should be given to the insulator selection and cathodic jet interaction with the insulator surface.