GLTRS--Glenn
TITLE AND SUBTITLE:
Ferroelectric Emission Cathodes for Low-Power Electric Propulsion

AUTHOR(S):
Scott D. Kovaleski

REPORT DATE:
September 2002

FUNDING NUMBERS:
WU-755-B4-04-00
NAS3-00145

PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES):
QSS Group, Inc.
21000 Brookpark Road
Cleveland, Ohio 44135

PERFORMING ORGANIZATION REPORT NUMBER:
E-13554

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

REPORT TYPE AND DATES COVERED:
Final Contractor Report

SPONSORING/MONITORING AGENCY REPORT NUMBER:
NASA CR-2002-211872
AIAA-2002-4242

SUPPLEMENTARY NOTES:
Prepared for the 38th Joint Propulsion Conference and Exhibit cosponsored by AIAA, ASME, SAE, and ASEE, Indian-
apolis, Indiana, July 7-10, 2002. Project Manager, Tom Burke, Systems Engineering Division, NASA Glenn Research Center, organization code 7800, 216-433-5712.

ABSTRACT:
Low- or no-flow electron emitters are required for low-power electric thrusters, spacecraft plasma contactors, andelectrodynamic tether systems to reduce or eliminate the need for propellant/expellant. Expellant-less neutralizers can improve the viability of very low-power colloid thrusters, field emission electric propulsion devices, ion engines, Hall thrusters, and gridded vacuum arc thrusters. The NASA Glenn Research Center (GRC) is evaluating ferroelectric emission (FEE) cathodes as zero expellant flow rate cathode sources for the applications listed above. At GRC, low voltage(100s to ~1500 V) operation of FEE cathodes is examined. Initial experiments, with unipolar, bipolar, and RF burst applied voltage, have produced current pulses 250 to 1000 ns in duration with peak currents of up to 2 A at voltages at or below 1500 V. In particular, FEE cathodes driven by RF burst voltages from 1400 to 2000 V peak to peak, at burst frequencies from 70 to 400 kHz, emitted average current densities from 0.1 to 0.7 A/cm2. Pulse repeatability as a function of input voltage has been initially established. Reliable emission has been achieved in air background at pressures as high as 10-6 Torr.

SUBJECT TERMS:
Electric propulsion; Cathodes; Ferroelectric materials

NUMBER OF PAGES:
16

PDF AVAILABLE FROM URL:
2002/CR-2002-211872.pdf
( 291 KB )
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