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Record Details

Record 19 of 25703
Mode Transitions in Hall Effect Thrusters
External Online Source: hdl:2014/44402
Author and Affiliation:
Sekerak, Michael J.(Michigan Univ., Ann Arbor, MI, United States)
Longmier, Benjamin W.(Michigan Univ., Ann Arbor, MI, United States)
Gallimore, Alec D.(Michigan Univ., Ann Arbor, MI, United States)
Brown, Daniel L.(Air Force Research Lab., Edwards AFB, CA, United States)
Hofer, Richard R.(Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA, United States)
Polk, James E.(Jet Propulsion Lab., California Inst. of Tech., Pasadena, CA, United States)
Abstract: Mode transitions have been commonly observed in Hall Effect Thruster (HET) operation where a small change in a thruster operating parameter such as discharge voltage, magnetic field or mass flow rate causes the thruster discharge current mean value and oscillation amplitude to increase significantly. Mode transitions in a 6-kW-class HET called the H6 are induced by varying the magnetic field intensity while holding all other operating parameters constant and measurements are acquired with ion saturation probes and ultra-fast imaging. Global and local oscillation modes are identified. In the global mode, the entire discharge channel oscillates in unison and azimuthal perturbations (spokes) are either absent or negligible. Downstream azimuthally spaced probes show no signal delay between each other and are very well correlated to the discharge current signal. In the local mode, signals from the azimuthally spaced probes exhibit a clear delay indicating the passage of "spokes" and are not well correlated to the discharge current. These spokes are localized oscillations propagating in the ExB direction that are typically 10-20% of the mean value. In contrast, the oscillations in the global mode can be 100% of the mean value. The transition between global and local modes occurs at higher relative magnetic field strengths for higher mass flow rates or higher discharge voltages. The thrust is constant through mode transition but the thrust-to-power decreased by 25% due to increasing discharge current. The plume shows significant differences between modes with the global mode significantly brighter in the channel and the near-field plasma plume as well as exhibiting a luminous spike on thruster centerline. Mode transitions provide valuable insight to thruster operation and suggest improved methods for thruster performance characterization.
Publication Date: Jul 14, 2013
Document ID:
20150008024
(Acquired May 19, 2015)
Subject Category: SPACECRAFT PROPULSION AND POWER
Document Type: Conference Paper
Meeting Information: AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit; 49th; 14-17 Jul. 2013; San Jose, CA; United States
Meeting Sponsor: American Inst. of Aeronautics and Astronautics; Los Angeles, CA, United States
American Society of Mechanical Engineers; Naperville, IL, United States
Society of Automotive Engineers, Inc.; Warrendale, PA, United States
American Society for Engineering Education; Urbana, IL, United States
Contract/Grant/Task Num: FA9550-09-1-0695
Financial Sponsor: Jet Propulsion Lab., California Inst. of Tech.; Pasadena, CA, United States
Air Force Research Lab.; Edwards AFB, CA, United States
Description: 37p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: HALL EFFECT; HALL THRUSTERS; PLASMAS (PHYSICS); PLASMA POTENTIALS; OSCILLATIONS; MAGNETIC FIELDS; MAGNETIC FLUX; AZIMUTH; MASS FLOW RATE
Other Descriptors: SATELLITE STATION-KEEPING; INTERPLANETARY EXPLORATION
Availability Source: Other Sources
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