Design Development and Test of the RIT-ÁX Mini Ion Engine System
Design Development and Test of the RIT-ÁX Mini Ion Engine System
Design Development and Test of the RIT-ÁX Mini Ion Engine System
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VI. Conclusion <strong>and</strong> Outlook<br />
The development <strong>of</strong> a <strong>RIT</strong>-µX miniaturized ion engine elegant breadboard model has been successfully<br />
completed. In an extensive functional test campaign <strong>the</strong> basic thruster performance has been mapped. For <strong>the</strong><br />
desired thrust range, 50-500µN, specific impulse <strong>and</strong> power consumption are available. The performance has been<br />
mapped also for lower <strong>and</strong> higher thrust levels. When sufficient power is available on board <strong>the</strong> spacecraft, <strong>RIT</strong>-µX<br />
is fully operable in an extended thrust range. With pervance tests <strong>the</strong> full thrust range has been validated with<br />
respect to <strong>the</strong> dynamic <strong>of</strong> ion optics. EBS tests showed that <strong>the</strong> dangerous effect <strong>of</strong> back streaming electrons is not<br />
critical for small ion engines. Especially, when operated with a gasless neutralizer <strong>the</strong> maximum available electron<br />
current is limited. Moreover, <strong>the</strong> ion optics design shows ample margins.<br />
Controllability <strong>and</strong> thrust noise are key issues for high precision low thrust systems. <strong>RIT</strong>-µX shows an<br />
impressive performance: The function between comm<strong>and</strong>ed thrust <strong>and</strong> thrust response is highly linear. The engine<br />
is mastering both small thrust variations <strong>and</strong> large thrust stepping. A thrust resolution better than +/- 0.1µN is found.<br />
The tests show clearly that that <strong>the</strong> limits for thrust resolution <strong>and</strong> controllability are given by <strong>the</strong> thruster electronics<br />
<strong>and</strong> not by <strong>the</strong> thruster itself.<br />
Finally, first thrust noise measurements have been performed. The measurement shows an electric thrust noise<br />
even bellow <strong>the</strong> limits for ESA's challenging LISA mission.<br />
In a first endurance test <strong>the</strong> engine has been operated for more than 1,700 hours at a constant thrust level <strong>of</strong> 500<br />
µN. The results will be published in a separate document.<br />
Meanwhile <strong>the</strong> European Space Agency has extended <strong>the</strong> baseline contract for <strong>the</strong> described activity. In <strong>the</strong><br />
frame <strong>of</strong> <strong>the</strong> extension all steps for <strong>the</strong> <strong>RIT</strong>-µX qualification will be performed. Completion <strong>of</strong> <strong>the</strong> qualification is<br />
scheduled for <strong>the</strong> second half <strong>of</strong> 2010. In parallel, ESA has granted contracts for <strong>the</strong> development <strong>of</strong> thruster<br />
electronics (Astrium Satellites, Friedrichshafen, D) <strong>and</strong> a dedicated flow control unit (Nanospace, S). A coupled<br />
system test is planned before end <strong>of</strong> 2010.<br />
References<br />
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41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference, Tucson, Arizona, July 10-13, 2005<br />
[2] H.Leiter et al. “<strong>RIT</strong>-µX - High Precision Micro <strong>Ion</strong> Propulsion <strong>System</strong> Based on RF-Technology”, 43rd<br />
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2007-5250<br />
[3]Horst W. Loeb et al.: <strong>Development</strong> <strong>of</strong> a <strong>RIT</strong>-Millithruster, IAC-04-S.4.04<br />
55th International Astronautical Congress, Vancouver, Canada, Oct. 4-8, 2004<br />
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Joint Propulsion Conference, Salt Lake City, UT, July 8-11, 2001<br />
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Joint Propulsion Conference <strong>and</strong> Exhibit, Huntsville, Alabama, July 20-23, 2003<br />
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[7] [H.J. Leiter et al.:Perfomance Inprovement <strong>of</strong> Radi<strong>of</strong>requency <strong>Ion</strong> Thrusters - The Evolution <strong>of</strong> <strong>the</strong> <strong>RIT</strong> 15 <strong>Ion</strong>, <strong>Engine</strong>, 26th<br />
International Electric Propulsion Conference, Kokuro-kita, Kitkyushu, Japan, 17.-21. Oktober 1999, Paper No. IEPC-99-154<br />
[8] H.J. Leiter et al.: <strong>RIT</strong> 15 S und <strong>RIT</strong> 15 LP - The <strong>Development</strong> <strong>of</strong> High Performance Mission Optimized <strong>Ion</strong> Thrusters, 35th<br />
Joint Propulsion Conference, Los Angeles, CA, 20.-24. Juni 1999, AIAA-Paper, No. 99-2444<br />
[9] Horst Loeb et al.: Forty-years <strong>of</strong> Giessen EP-Activities <strong>and</strong> <strong>the</strong> recent µN-<strong>RIT</strong>, IEPC-2005-031<br />
[10]Davar Feili et al.: Performance Mapping <strong>of</strong> new µN-<strong>RIT</strong>s at Giessen, IPEC-2005-252<br />
[11] H.Leiter et al. <strong>RIT</strong>-µX - The New Modular High Precision Micro <strong>Ion</strong> Propulsion <strong>System</strong> IEPC-2007-209<br />
9<br />
The 31st International Electric Propulsion Conference, University <strong>of</strong> Michigan, USA<br />
September 20 – 24, 2009