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dc power control for a liquid-fed resistojetA simple breadboard power controller was designed and demonstrated for a new liquid-fed water resistojet. The 1-piece laboratory model thruster has an integrated vaporizer/superheater using a single heating element. Heater temperature was maintained at or near a preset reference value with the closed loop controller providing pulse width modulated (PWM) dc power into the thruster heater. A combined thruster, temperature readout, PWM transfer function was experimentally determined. This transfer function was used to design a proportional plus integral controller that demonstrated zero steady state error, conservative stability margins and adequate transient response to step changes in propellant flow rate, input voltage and temperature reference. Initial turn-on temperature overshoot from room temperature to a 650 C setpoint was 80 C. In addition, EMI was alleviated by reducing heater dI/dt and dV/dt using a simple diode-inductor-capacitor network. Based on limited initial tests, thruster preheat with no propellant flow was necessary to achieve stable system operation during startup. Breadboard power efficiency was 99 percent at 1 kW, and component mass was 0.4 kg excluding the power loss and mass of an input filter required for spacecraft integration.
Document ID
19890060086
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Gruber, Robert P.
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
August 14, 2013
Publication Date
January 1, 1988
Subject Category
Spacecraft Propulsion And Power
Meeting Information
Meeting: International Electric Propulsion Conference
Location: Garmisch-Partenkirchen
Country: Germany
Start Date: October 3, 1988
End Date: October 6, 1988
Sponsors: AIAA, Japan Society of Aeronautical and Space Sciences, DGLR
Accession Number
89A47457
Distribution Limits
Public
Copyright
Other

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