GLTRS--Glenn
TITLE AND SUBTITLE:
Integration Issues of a Plasma Contactor Power Electronics Unit

AUTHOR(S):
Luis R. Piņero, Kenneth W. York, and Glen E. Bowers

REPORT DATE:
June 1995

FUNDING NUMBERS:
WU-478-43-00

PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
Lewis Research Center
Cleveland, Ohio 44135-3191

PERFORMING ORGANIZATION REPORT NUMBER:
E-9739

SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
Washington, D.C. 20546-0001

REPORT TYPE AND DATES COVERED:
Technical Memorandum

SPONSORING/MONITORING AGENCY REPORT NUMBER:
NASA TM-106977
AIAA-95-362

SUPPLEMENTARY NOTES:
Prepared for the 30th Intersociety Energy Conversion Engineering Conference cosponsored by ASME, IEEE, AIChE, ANS, SAE, ASC, and AIAA, Orlando, Florida, July 31-August 4, 1995. Luis R. Piņero, NASA Lewis Research Center; Kenneth W. York, Analex Corporation, 3001Aerospace Parkway, Brook Park, Ohio 44142 (work funded by NAS3-25776); Glen E. Bowers, Gilcrest Electric, 3000 Aerospace Parkway, Brook Park, Ohio 44142 (work funded by NASA Contract NAS3-27351). Responsible person, Luis R. Piņero, organization code 5330, (216) 433-7428.

ABSTRACT:
A hollow cathode-based plasma contactor is baselined on International Space Station Alpha (ISSA) for spacecraft charge control. The plasma contactor system consists of a hollow cathode assembly (HCA), a power electronics unit (PEU), and an expellant management unit (EMU). The plasma contactor has recently been required to operate in a cyclic mode to conserve xenon expellant and extend system life. Originally, a DC cathode heater converter was baselined for a continuous operation mode because only a few ignitions of the hollow cathode were expected. However, for cyclic operation, a DC heater supply can potentially result in hollow cathode heater component failure due to the DC electrostatic field. This can prevent the heater from attaining the proper cathode tip temperature for reliable ignition of the hollow cathode. To mitigate this problem, an AC cathode heater supply was therefore designed, fabricated, and installed into a modified PEU. The PEU was tested using resistive loads and then integrated with an engineering model hollow cathode to demonstrate stable steady-state operation. Integration issues such as the effect of line and load impedance on the output of the AC cathode heater supply and the characterization of the temperature profile of the heater under AC excitation were investigated.

SUBJECT TERMS:
Power electronics; Plasma contactor; Hollow cathodes

NUMBER OF PAGES:
08

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