Vacuum arc thruster
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A vacuum arc thruster (VAT) is a form of electric spacecraft propulsion. It uses a vacuum arc discharge, across an insulator, between two electrodes to produce thrust. A metal plasma is produced from micrometer-size cathodic spots and the momentum from the plasma creates thrust for the vacuum arc thruster.[1] Thus, whereas the insulator is used as propellant in a pulsed plasma thruster, in a VAT the solid metallic cathode is consumed as propellant.[2] Vacuum arc thrusters are used for propulsion on CubeSats, microsatellites, and nanosatellites.[2][1]
Thruster arrays
Vacuum arc thrusters are sometimes implemented in multi-unit arrays, in which two or more devices are arranged in a grid configuration. Because individual VATs provide low impulse per pulse, VAT arrays can increase the total impulse and improve reliability. The off-axis placement of thrusters allows for rotational motion which can be used for altitude control. However, VAT arrays require a larger power processing unit and an additional control system which pose integration issues for CubeSats and other small satellites.
Some VAT array designs implement cathode architectures where multiple discharge sites are integrated into a single device rather than integrated as several thrusters. In these configurations, the central segments are the primary source of propulsion and the peripheral segments can be used for altitude control. Segmented VAT arrays can also provide fine velocity adjustments for satellite formation flying.[3]
