Electric Thruster Based on Plasma Propulsion including Power Processing Unit

Objectives

The European satellite industry is engaged in the ESA Large Platform mission project, a new high performance satellite platform with a payload power range between 12 and 18 kW, developed jointly by Alcatel Space and Astrium within the ALPHABUS team. This project will enhance the European competitiveness on the satellite world market.

The new platform requires the introduction of advanced technologies in a number of areas. Electric propulsion is one such key technology for this new platform.

This project, carried out between March 2003 and December 2004, had as a goal the pre-development of an electric thruster with its associated power processing unit. The Hall-effect stationary plasma thruster solution, which was the subject of this contract, will have a thrust just under 200 mN with a specific impulse higher than 2200 s, a 30 % increase with respect to the current state of the art. Its power level is as high as 5 kW, which in turn is more than three times higher than the currently qualified European Hall-effect thrusters.

Under the present program, Snecma Moteurs and ETCA were able to carry out the successful pre-development of the technologies and solutions necessary for an efficient and competitive high power Hall-effect thruster subsystem. Development activities have begun for the flight-model thruster, called PPS®5000, along with its associated high power processing unit (HPPU).







Conceptual schematic of PPS®5000 on lightweight orientation mechanism



click for larger image



The PPS®X000, a technological demonstrator for the PPS®5000


Challenges

Current, state of the art Hall (plasma) thrusters operating at lower power levels have demonstrated long operational lifetimes. A key issue addressed in this project - and a very significant step forward indeed -  was the demonstration of long life capability for a Hall thruster at high discharge voltage (> 500 V). Such a voltage level provides a very promising combination of specific impulse -  or propellant use efficiency - and thrust-specific power, in kW/N, which is a measure of the cost of generating the desired thrust.

Another challenge addressed in this project is the design of a highly efficient (95 %) High Power Processing Unit providing 5kW.

Benefits

By increasing its specific impulse, Hall effect technology will allow satellite manufacturers to consider station keeping performance close to that which can be reached by gridded ion engines: the slightly lower Isp is balanced by a lower system dry mass and lower recurring costs.

In addition, with their extended range of throttleability and low to very-low thrust-specific power operating points, Hall thrusters can bring a decisive advantage for orbit transfer manoeuvres.

Finally, the present program is at the forefront of world efforts toward the development of high specific impulse Hall-effect thrusters. Such devices already qualified or currently in the process of becoming flight-qualified in the US or in Russia are limited to 400 V (specific impulse below 2000 s). The European Hall-effect thruster technology will thus appear as a unique solution not only for the mid- to long-term geostationary satellites world market, but also for many space exploration missions.

Features

The high power Hall-effect thruster subsystem proposed under this contract is dedicated to station keeping and possibly orbit topping duties for large platform. Thus, it involves at least 4 Hall-effect thrusters along with their cathode (one cathode per thruster can be sufficient), their Xenon Flow Controllers (one XFC per cathode) and their electrical supplies.

Each thruster electrical supply includes the thruster power supplies themselves, as well as an electrical Filter Unit (FU) for impedance matching and EMI/ESD protection between the thruster and its supplies, and harnesses to connect the different subsystem components.

The thruster power supplies (discharge supply, cathode heater supply, cathode ignitor supply, magnets supply, XFC supplies) are implemented in the Power Processing Unit (PPU). The number of PPUs (one or two thrusters per PPU) and FUs (FU implemented in the PPU or standalone FU) will depend of the subsystem trade-offs.

Plan

As early as end of 1999, Snecma Moteurs and Alcatel/ETCA started activities on a high power Hall-effect thruster solution. In addition, with CNES and ESA support, a technological demonstrator thruster called PPS®X000 and a Bread Board HPPU anode supply have been manufactured and tested.

In a first part of the activity, PPS®X000 characterization tests were extended up to 1000 V and over 6 kW of discharge voltage and power, respectively. A thrust level of 340 mN was measured, as well as a specific impulse in excess of 3200 s. A short-duration endurance test at 700 V was also carried out, and was followed by a successful 1000-hr endurance test at 550 V, a world-record discharge voltage for an endurance test on a Hall thruster.

The two HPPU anode supply modules have been tested up to 800 V / 6 kW, with a measured efficiency of 95% at 700 V / 5 kW. A joint test between the PPSÃ’X000 and the HPPU anode supply Bread Board was also successfully conducted in October 2004. This test served as a validation of the coupling between the anode supply and the technology demonstrator thruster.

The PPSÃ’5000 is the flight-design, 1:1 scale version of the PPS®X000 technology demonstrator. The PPS®5000 Preliminary Design Review (PDR) was held at beginning of September 2004, and will be followed by a PDR closing beginning of December 2004 when the HPPU design and breadboard were also completed.

Current status


  • Predevelopment is now completed.

  • High voltage characterisation tests of the PPSÃ’X000 have been performed, and demonstrated capabilities of thrust and specific impulse for the PPS®X000 up to 340 mN and 3200 s, respectively.

  • A 1000-hr endurance test was also successfully completed on the PPSÃ’X000, at 4.5 kW and 550 V of thruster power and discharge voltage, respectively (specific impulse: 2200 s).

  • The HPPU breadboard, including two anode modules, has been tested up to 800V / 6kW. An efficiency of 95 % was measured at 700V / 5kW. The HPPU breadboard was then successfully coupled with the PPS®X000 and operated at 550V, 350V and 300V in October 2004.

  • The PDR data package has been issued and the PDR was successfully held between September 2004 and December 2004.

Contacts

Status date

Friday, August 10, 2007 - 14:21