Simulating a 1-kW arcjet thruster using a nonlinear active load
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Publications and source records attributed to Altenburger, Gene P..
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Arcjet thrusters are known to have distinctly nonlinear electrical characteristics with negative incremental resistance throughout their normal operating region. The 1-kW arcjet simulator proposed here accurately mimics these characteristics statically, and dynamically up to 40 kHz. Testing with a power-processing unit (PPU) and the simulator, a 1-kW arcjet, and a resistive load bank established that the simulator accurately predicted the transient behavior of the PPU-arcjet combination, while the resistive load bank did not. The simulator uses resistors and insulated-gate bipolar transistors to dissipate the PPU output power; a nonlinear feedback is applied to produce the desired v-i characteristics. This feedback is analyzed dynamically. The arcjet simulator allows development of a PPU to a higher level of confidence before beginning testing at an arcjet facility.
A 1 kW electronic load was programmed to simulate the nonlinear i-v (volt-ampere) characteristics of an arcjet, both ignited and unignited. The simulator was tested and found to closely resemble an arcjet both for large transients and small perturbances up to about 40 kHz. No attempt was made to simulate the ignition process itself. The dynamic behavior of the arcjet (and the simulator) was shown to differ significantly from that of a resistor bank. Previous research led to the design and construction of a 1 kW arcjet power supply. A high voltage ignition circuit was added to this hardware, and tests on a 1 kW arcjet were performed at NASA-Lewis. All tests were successful and no ignition failures were observed. Circuit documentation and test results are included.