Experimental study of acceleration processes in Hall Effect Thrusters

Paper number

IAC-12,E2,1,8,x16322

Author

Mr. Julien Vaudolon, CNRS, France

Year

2012

Abstract

Chemical spacecraft propulsion systems create thrust by thermodynamically expanding heated propellant gas
through a nozzle. Chemical propulsion allows generation of a large thrust level. As a direct consequence, it is possible
for the spacecraft to quickly reach a high speed. However, the fast propellant consumption becomes a drawback for
long-distance missions since either very large tanks are needed or the firing phase will be very short. The stability of
the chemical propellant during a long time period is also a critical issue. Besides, many desirable future space
missions require velocity increments that are an order of magnitude, or more, higher than this. For missions that
require a high velocity increment (such as orbit transfer, de-orbit manoeuvre and interplanetary journeys), an
alternative method of propulsion having a higher specific impulse or exhaust gas velocity can be achieved using
electric propulsion (EP). The Gridded Ion Engine (GIE) and the Hall Effect Thruster (HET) are presently two EP
propulsion devices mature enough with a long flight heritage to be envisaged as a solid option for main spacecraft
propulsion in the case of outer planet exploration and science missions. Although GIE devices are able to attain very
high specific impulse exceeding 4000 s at moderate applied power with xenon as a propellant, the ion current flowing
through the grid assembly is limited by the Child-Langmuir principle, meaning a restricted thrust level. In other words,
a large thrust can only be achieved with a very large grid area, which generates technological constraints and issues.
The high thrust-to-power ratio (3 to 4 times as big as GIEs), the efficiency and the lifetime of HETs give this technology
a serious advantage for primary propulsion of space probes during interplanetary journeys (as demonstrated by the
successful SMART-1 Moon flyby mission of the European Space Agency).

Abstract document

IAC-12,E2,1,8,x16322.brief.pdf

Manuscript document

IAC-12,E2,1,8,x16322.pdf (🔒 authorized access only).

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