Description:
Princeton Docket # 12-2808
Researchers at Princeton Plasma Physics Laboratory have developed a
novel method to achieve feedback control of low-frequency azimuthal waves
(rotating spoke oscillation) in the ExB discharge of a Hall thruster. This technology will enhance thruster
efficiency and performance.
The Hall thruster is a plasma-based propulsion system for
satellites and in the future, space vehicles. The field
traps electrons in azimuthal ExB orbits inside the thruster channel,
neutralizing the ion space charge and allowing the Hall thruster to produce a
high thrust density. With a typical
propellant velocity around 20 km/s, and thrust from 10-1000 mN, Hall thrusters
are attractive for orbit station-keeping, orbit insertion, and inner-planetary
missions. However, the
efficiency of the thruster is degraded by azimuthal oscillations that increase
electron transport to the anode. Further, electromagnetic interference
from plasma oscillations in the thruster can interfere with satellite
electronics. Thus, there is an
urgent need for controlling the azimuthal oscillations in the Hall thrusters.
Princeton
researchers have designed a special anode that is split azimuthally into a
number of segments. The current to each segment oscillates as the rotating spoke
passes over it, and feedback is accomplished by either by resistors connected in
series with each anode segment or more complex passive feedback circuitry
comprising resistor, inductor and/or capacitor and or active feedback, which
causes the voltage on a segment to decrease in proportion to the current through
that segment. A laboratory
prototype of this system with feedback based on resistors has been fabricated
and demonstrates that this new method can suppress a coherent azimuthal wave in
a Hall thruster and decrease the time-averaged total discharge current by up to
13.2%.
Applications
·
To suppress azimuthal oscillations in Hall thrusters and other ExB
devices
·
To excite and control azimuthal
oscillations
Advantages
·
Enhanced Hall thruster performance by reducing electron cross-field
transport
·
Improved Hall thruster efficiency by allowing the production of
more thrust for a given power input
·
More stable operation of the Hall
thruster
Intellectual Property
status
Patent
protection is pending.