Sensitivity Testing of the NSTAR Ion Thruster IEPC-2007-010

Content Provider	Semantic Scholar
Author	Sengupta, Anita Anderson, John Brophy, John R.
Copyright Year	2007
Abstract	During the Extended Life Test (ELT) of the DS1 flight spare ion thruster, the engine was subjected to sensitivity testing in order to characterize the dependence of discharge plasma production on operating conditions and component wear. The discharge chamber sensitivity to small variations in main flow, cathode flow, beam current, and grid voltages, was determined for 0.5 to 2.3 kW operation. The degree of variation was consistent with the control band provided by the DS1 PPU and feed system (3-5%). For each power level investigated, 16 high/low operating conditions were chosen to vary the flows, beam current, and grid voltages in a matrix that mapped out the entire parameter space. The matrix of data generated was used to determine the partial derivative or sensitivity of the dependent discharge parameters to the variations in the independent parameters (throttle set points). The sensitivities of each dependent parameter with respect to each independent parameter were determined using a least-squares fit routine. Several key findings have been ascertained from the sensitivity testing. Discharge operation is most sensitive to changes in cathode flow and to a lesser degree main flow. The data also confirms that the NSTAR thruster plasma production is limited by primary electron input for a fixed neutral population. Key sensitivities along with their change with thruster wear (operating time) will be presented. In addition double ion content measurements with an ExB probe will be presented to illustrate beam ion content sensitivity to discharge chamber operating parameters.
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Alternate Webpage(s)	http://erps.spacegrant.org/uploads/images/images/iepc_articledownload_1988-2007/2007index/IEPC-2007-010.pdf
Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article