Assessment of the T5 and T6 Hollow Cathodes as Reaction Control Thrusters

Abstract

Hollow cathodes have been proposed as reaction control thrusters for all-electric and small spacecraft. This paper makes an assessment of modified T5 and T6 hollow cathodes for use as millinewton range thrusters. The influence of terminal parameters such as discharge current, mass flow rate, and cathode/anode geometry on thrust production is discussed. The data indicate that the T5 cathode may be able to develop specific impulses in the range of 150-250 s with argon at reasonable thrust efficiencies of up to 14%. As such, hollow-cathode thrusters may meet some limited applications. However, it is unlikely that this type of thruster could be improved significantly or could compete with similar thrusters in the same operating range. High specific impulse operation is also shown to develop large discharge voltage fluctuations, which may significantly limit the lifetime of such a device.

Microplasma thruster powered by X-band microwaves

“…A comparison of representative operating parameters/conditions and thrust performance is given in Table II, for several microplasma thrusters of electrothermal type (with power inputs on the order of 1-10 W) that have so far been reported in the literature. [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49]…”

“…The electromagnetic thrusters rely on the plasma acceleration via interaction of the current and magnetic fields: micro pulsed plasma thrusters. 31,32 The electrothermal thrusters rely on the plasma/gas heating via plasma discharge followed by supersonic plasma/ gas expansion through de Laval nozzles: micro arcjet thrusters, 33,34 hollow cathode thrusters, 35 and plasma thrusters using dc microdischarges, 36,37 ac/rf microcavity discharges, 38,39 capacitively coupled rf discharges in a dielectric tube, [40][41][42][43][44][45][46][47] and microwave discharges. 48,49 We have developed a mm-scale microplasma thruster of the electrothermal type with azimuthally symmetric surface wave-excited plasmas (SWPs), [50][51][52][53][54][55][56][57][58] consisting of a microplasma source followed by a converging-diverging micronozzle as schematically shown in Fig.…”

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

“…The second is electric propulsion, which can be grouped into three distinct categories: electrothermal, electrostatic, and electromagnetic. Electrothermal propulsion includes devices like arcjets [4][5][6], resistojets [7], hollow cathode thrusters [8,9], and the Pocket Rocket microthruster [10] which is the subject of this paper. Electrostatic propulsion has been dominated by a large variety of gridded ion thrusters, the most recent developments including NASA's annular-geometry ion engine (AGI-Engine) [11,12] and the NASA evolutionary xenon thruster (NEXT) [13,14], but also include experimental technologies like the field emission electric propulsion (FEEP) concept [15] and its precedent colloid thrusters.…”

Validation of an additively manufactured resistojet through experimental and computational analysis

“…Such performance can result in either propellant mass savings or increased capability with respect to cold gas thrusters [4]. The primary application for a high performance resistojet is for primary propulsion on small satellite platforms [5] with an emerging possibility of utilisation as a secondary propulsion system for all-electric telecommunication satellite platforms, where a complement of thrusters would form a reaction control system (RCS) using xenon as a common propellant in combination with a primary electric propulsion system [6].…”