Electric propulsion for satellites and spacecraft: established technologies and novel approaches

Abstract

This contribution presents a short review of electric propulsion technologies for satellites and spacecraft. Electric thrusters, also termed ion or plasma thrusters, deliver a low thrust level compared to their chemical counterparts, but they offer significant advantages for in-space propulsion as energy is uncoupled to the propellant, therefore allowing for large energy densities. Although the development of EP goes back to the 1960's, the technology potential has just begun to be fully exploited because of the increase in the available power aboard spacecrafts, as demonstrated by the very recent appearance of all-electric communication satellites. This article first describes the fundamentals of EP: momentum conservation and the ideal rocket equation, specific impulse and thrust, figures of merit and a comparison with chemical propulsion. Subsequently, the influence of the power source type and characteristics on the mission profile is discussed. Plasma thrusters are classically grouped into three categories according to the thrust generation process: electrothermal, electrostatic and electromagnetic devices. The three groups, along with the associated plasma discharge and energy transfer mechanisms, are presented via a discussion of long-standing technologies like arcjet thrusters, MPD thrusters, pulsed plasma thrusters, ion engines as well as Hall thrusters and variants. More advanced concepts and new approaches for performance improvement are discussed afterwards: magnetic shielding and wall-less configurations, negative ion thrusters, and plasma acceleration with a magnetic nozzle. Finally, various alternative propellant options are analyzed and possible research paths for the near future are examined.

A Comprehensive Cold Gas Performance Study of the Pocket Rocket Radiofrequency Electrothermal Microthruster

“…Finally, electromagnetic propulsion boasts the mature Hall-effect thruster [16] and its variants [17][18][19], as well as newer technologies like magnetoplasmadynamic (MPD) thrusters [20,21] and ablative pulsed plasma thrusters (PPTs) [22]. For more information, a comprehensive review of electric propulsion is available in Charles [23] and Mazouffre [24], while Micci and Ketsdever [25] and Scharfe and Ketsdever [26] compiles a review of both classes of propulsion technologies with a specific focus on micropropulsion for microspacecraft.…”

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

“…123 The function of the cathode neutralizer is threefold: (1) it serves as the negative terminal of the thruster circuit, thus responsible for the generation of the thruster's accelerating electric field; (2) it produces sufficient electrons to neutralize the ion beam ejected from the thruster; and (3) it generates the primary electrons for the thruster unit ignition process. To couple with Hall and ion micro-thrusters, the cathode must be able to generate discharge current levels below 1 A.…”

“…17 From this perspective, they compare favorably to solid and liquid . Electric propulsion systems demonstrate much higher exhaust velocities reaching 10 4 m  s À1 (and importantly, there are no physical limitations for the further enhancement), but at significantly lower thrust levels and thrust-to-weight ratios not exceeding 0.01; hence, these systems are not capable of launching the vehicle from the Earth's surface.…”

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].…”