A Review of Low-Power Electric Propulsion Research at the Space Propulsion Centre Singapore

Abstract

The age of space electric propulsion arrived and found the space exploration endeavors at a paradigm shift in the context of new space. Mega-constellations of small satellites on low-Earth orbit (LEO) are proposed by many emerging commercial actors. Naturally, the boom in the small satellite market drives the necessity of propulsion systems that are both power and fuel efficient and accommodate small form-factors. Most of the existing electric propulsion technologies have reached the maturity level and can be the prime choices to enable mission versatility for small satellite platforms in Earth orbit and beyond. At the Plasma Sources and Applications Centre/Space Propulsion Centre (PSAC/SPC) Singapore, a continuous effort was dedicated to the development of low-power electric propulsion systems that can meet the small satellites market requirements. This review presents the recent progress in the field of electric propulsion at PSAC/SPC Singapore, from Hall thrusters and thermionic cathodes research to more ambitious devices such as the rotamak-like plasma thruster. On top of that, a review of the existing vacuum facilities and plasma diagnostics used for electric propulsion testing and characterization is included in the present research.

Introduction to Plasma Based Propulsion System: Hall Thrusters

“…In chemical thruster, the exhaust velocity depends to thermal heating, which cannot reach very high magnitude. In a chemical thruster, the propellant is burned and the hot gas is expelled from the thruster with the help of a nozzle but in plasma thrusters the plasma expels without an explosion taking place [2,3,[5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The performances of different types of electric thrusters have been discussed in Table 1.…”

“…Unlike chemicals and electric rockets (solid rocket motors, liquid rocket engines and hypergolic engines), the propulsion thrust in a Hall thruster is achieved by a propellant (usually Xenon). Typical chemical thruster specific impulses range around 200-500 sec, though electric thrusters can have specific impulses up to 3000 sec or greater [1,[5][6][7]19]. The pressure inside the channel is on the order of 0.1 Pa. Now a days, most of the countries are using the Hall thruster technology in their space mission.…”

“…One of them is a stationary plasma thruster (has an extended acceleration zone) and second is a thruster with anode layer (has a more narrow acceleration zone). The electric field of strength $1000 V/ m gets generated inside the discharge channel along the axial direction of the device [5]. ISRO (India) used Hall effect ion propulsion thrusters in GSAT-4 back in 2010, carried by GSLV Mk2 D3.…”

“…Hollow cathodes are used in Hall thruster to provide electrons (with the help of DC electron-discharge plasma generator) to neutralize the body of the spacecraft (to manage spacecraft charging) as well to sustain the plasma discharge and. The hollow cathode are made up with refractory metal tube and lanthanum hexaboride [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. The cathode operates at 30 V to 40 V negative of the anode in a mercury thruster depending on the design consideration.…”

Incident-angle dependence of deformation characteristics of aluminum surface under low-energy xenon-ion impact

“…Electric propulsion, a key and revolutionary technology for the new generations of satellites, has attracted considerable attention in recent years due to its outstanding advantages such as superior fuel efficiency, unprecedented specific impulse, high thrust precision, low costs, and long endurance [1][2][3][4]. These properties make it promising technology for potential applications in a broad range of fields such as orbit correction and deep space exploration [5,6].…”