Physics
Scientific paper
Dec 1991
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1991jpl..rept.....b&link_type=abstract
Annual Report, 1990 Jet Propulsion Lab., California Inst. of Tech., Pasadena.
Physics
Computerized Simulation, Interplanetary Spacecraft, Ion Engines, Ion Propulsion, Systems Integration, Throttling, Charge Exchange, Hollow Cathodes, Plasmas (Physics), Xenon
Scientific paper
The work performed on the Ion Propulsion System Technology Task in FY90 is described. The objectives of this work fall under two broad categories. The first of these deals with issues associated with the application of xenon ion thrusters for primary propulsion of planetary spacecraft, and the second with the investigation of technologies which will facilitate the development of larger, higher power ion thrusters to support more advanced mission applications. Most of the effort was devoted to investigation of the critical issues associated with the use of ion thrusters for planetary spacecraft. These issues may be succinctly referred to as life time, system integration, and throttling. Chief among these is the engine life time. If the engines do not have sufficient life to perform the missions of interest, then the other issues become unimportant. Ion engine life time was investigated through two experimental programs: an investigation into the reduction of ion engine internal sputter erosion through the addition of small quantities of nitrogen, and a long duration cathode life test. In addition, a literature review and analysis of accelerator grid erosion were performed. The nitrogen addition tests indicated that the addition of between 0.5 and 1.0 percent of nitrogen by mass to the xenon propellant results in a reduction in the sputter erosion of discharge chamber components by a factor of between 20 and 50, with negligible reduction in thruster performance. The long duration test of a 6.35-mm dia. xenon hollow cathode is still in progress, and has accumulated more than 4,000 hours of operation at an emission current of 25 A at the time of this writing. One of the major system integration issues concerns possible interactions of the ion thruster produced charge exchange plasma with the spacecraft. A computer model originally developed to describe the behavior of mercury ion thruster charge exchange plasmas was resurrected and modified for xenon propellant. This model enables one to calculate the flow direction and local density of the charge exchange plasma, and indicates the degree to which this plasma can flow upstream of the thruster exhaust plane. A continuing effort to investigate the most desirable throttling technique for noble gas ion thrusters concentrated this year on experimentally determining the fixed flow rate throttling range of a 30-cm dia. thruster with a two-grid accelerator system. These experiments demonstrated a throttling capability which covers a 2.8 to 1 variation in input power. This throttling range is 55 percent greater than expected, and is due to better accelerator system performance at low net-to-total voltage ratios than indicated in the literature. To facilitate the development of large, higher power ion thrusters several brief studies were performed.
Brophy John R.
Garner Charles E.
Goodfellow Keith D.
No associations
LandOfFree
Electric propulsion system technology does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Electric propulsion system technology, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electric propulsion system technology will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1540178