ALCATEL SPACE PLASMA PROPULSION SUBSYSTEM QUALIFICATION STATUS

Transcription

1 ALCATEL SPACE PLASMA PROPULSION SUBSYSTEM QUALIFICATION STATUS Pascal GARNERO, Olivier DULAU ALCATEL SPACE 100, Bd. du Midi, BP CANNES LA BOCCA Cedex FRANCE Contact : pascal.garnero@space.alcatel.fr, olivier.dulau@space.alcatel.fr IEPC INTRODUCTION This article presents the main performed qualification tests for the ALCATEL SPACE Plasma Propulsion. The objective of these qualification tests was to demonstrate capability of the Plasma Propulsion Subsystem to operate in an environment simulating the orbit conditions. These tests complete qualification for use of Plasma Propulsion onto SPACEBUS family platform. These tests allow ALCATEL SPACE to access to an exhaustive data bank of parameters during the Plasma Propulsion life. 1. PLASMA PROPULSION SUBSYSTEM LIFE TEST ALCATEL SPACE is presently using FAKEL SPT100 thrusters on its SPACEBUS spacecraft. In this frame, ALCATEL SPACE, in coordination with CNES and SNECMA, started a subsystem life test mid 1998 to demonstrate on ground the actual performances of the subsystem over a complete satellite mission (15 years) in ambient temperature conditions. In order to be more representative of the orbit temperature conditions, ALCATEL SPACE has performed specific cold starts at FAKEL's facilities with the same thruster. 501 hours of firing have been performed with cold starts, 102 at the beginning of life and 399 at the end of the required operational life. Elements of the cathode are sensitive to cold starts. So an additional thermal vacuum life test has been performed on a SPT100 cathode. 1.1 Plasma Propulsion Life Test at Ambient Temperature At SNECMA s facilities, a flight representative Plasma Propulsion Subsystem has been accommodated in the test set-up. It includes the following flight representative hardware : One Stationary Plasma Thruster (SPT100 QM) FAKEL (SPT100 S/N 49) Two Xenon Flow Controllers (XFC QM) - FAKEL One Power Processing Unit (PPU QM) ALCATEL ETCA One Filter Unit (FU QM) SNECMA/EREMS One Pressure Regulator (identical to FM) MU-SPACE COMPONENTS A set of representative tubing and harness

2 data acquisition and control SPT100 Simulator PPU EGSE Vacuum Chamber Test EGSE PPU/TSU FU SPT100 < Vacuum Chamber Pressure Regulator XFC Xenon Ground Support Storage Electrical harnesss Xenon tubing XXX : Flight like equipment Management of test parameterss XXX : Ground support equipment Figure 1 : PPS Life Test Set-Up The current status of the life test is that 6900 hours of firing and 2700 cycles have been performed, that represents the nominal duration for the foreseen satellite mission of ASTRA 1K (13 years), including 1.5 margin factor. This current status allows to present now the performance of the whole Plasma Propulsion Subsystem over a satellite mission : Thrust 100 1rst cold cycles 2nd cold cycles Thrust (mn) SPT100 cumulated firing (hours) Figure 2 : Thrust Evolution during PPS Life Test

3 Thrust deviation to local mean Frequency Thrust deviation (mn) 0 Figure 3 : Thrust Deviation during PPS Life Test Specific Impulse rst cold cycles 2nd cold cycles ISP (s) SPT100 cumulated firing (hours) Figure 4 : Specific Impulse Evolution during PPS Life Test Efficiency 0.6 1rst cold cycles 2nd cold cycles Efficiency SPT100 cumulated firing (hours) Figure 5 : Specific Impulse Evolution during PPS Life Test

4 Note : Efficiency calculation Method : 2 Thrust η = 2. MassFlowRa te. ElectricPower Figure 6 : View of SPT100 after 6900 hours of Firing The life test will be extended until 8900 hours of thruster firing to demonstrate a 1.5 margin coefficient over the nominal required lifetime for the heaviest SPACEBUS platforms. 1.2 SPT100 Cold Starts In order to be more representative of the orbit temperature conditions, ALCATEL SPACE has decided to perform specific cold starts at Fakel's facilities in the frame of the Plasma Propulsion Subsystem Life Test. 501 cold starts have been performed on the SPT100 S/N49 : 1 st test cycle : 102 cycles (1167 hours to 1269 hours of total firing duration of the Plasma Propulsion Subsystem Life Test) 2 nd test cycle : 399 cycles (4387 hours to 4786 hours of total firing duration of the Plasma Propulsion Subsystem Life Test) This test was carried out on Fakel's facilities from December 1999 to February 2000 and from April to June 2001.

5 During this test only the qualification model thruster and the associated XFCs are included. The SPT power is a PPU test bench provided by FAKEL. XFCs temperatures are not specified for this test and shall only remain into their qualification domain. The thruster is mounted in the thermal test bench used for acceptance and qualification thermal tests. This bench is represented here below. Thruster Front Thermal Screen XFCs The material under test is cooled via liquid nitrogen thermal screens, simulating the radiation towards space. Excessive cooling is prevented by electrical heaters. Before thruster start, front screen is removed, in order to allow the plume ejection and Xenon pumping. Each test cycle consisted of one sequence per day. Each sequence includes : - Thruster cooling down to 44 C at least - One hour firing at nominal operating point (300 ± 3 V ; 4.5 ± 0.1 A) - Thruster cooling down to 25 C at least - One hour firing (same conditions) - Thruster cooling down to 25 C at least - One hour firing (same conditions) During 1 st test cycle, this sequence has been repeated 33 times (on cathode K1) + 1 time (on cathode K2) at the end. During 2 nd test cycle, the sequence has been repeated as follow : 1 st Part : [32 times (on K1) + 1 time (on K2)] twice + 1 time (on K1) at the end 2 nd Part : 31 times (on K1) + 1 time (on K2) + 33 times (on K1) + 1 time (on K2) 1.3 SPT100 Cathode Thermal Vacuum Test Elements of the cathode are sensitive to cold starts. An additional thermal vacuum test was carried out on ALCATEL SPACE facilities on a cathode of the qualification model SPT100 S/N9. The aim of this test was to make on the specimen 3700 vacuum cycles of switch ON / OFF in cold environment.

6 Cathode switch OFF 20 C -37 C 160 s Cathode switch ON 3700 cycles The cathode has been mounted on the base plate of the thermal equipment. A cover was screwed on this plate to make the specimen environment steady. When the cathode cold temperature was reached, the cathode was switched ON during 160 s (nominal warmup procedure in flight) and switch OFF again. The thermal vacuum test has been done under better than 10-5 mbar pressure. The specimen was equipped with 4 thermocouples : 2 mounted on cathode foot 2 mounted on cathode body Figure 7 : View of SPT100 Cathode with thermocouples All of the 3700 switch ON/OFF cycles have been done. All of the specifications on specimen s temperature level and cycle length have been respected, namely : -37 C on the 4 specimen TC for the cold level, max temperature on cathode body was +260 C,

7 Cathode Life Test - Resistance & Power R à froid R à chaud Puissance Ohms Watts Cycles After this SPT100 cathode thermal vacuum test, the cathode has been reinstalled on the SPT100 S/N9. The thruster has been fired and all the parameters were nominal. 1.4 Conclusion on the Plasma Propulsion Subsystem Life Test The qualification was already achieved at equipment level and this life test has demonstrated the qualification of an integrated Plasma Propulsion Subsystem. The three kinds of tests has allowed to fully qualify the ALCATEL SPACE Plasma Propulsion Subsystem in a space representative environment. The obtained results are consistent with the previous SPT100 life tests (SPT100 S/N3 and S/N5). 2. THRUSTER MODULE / PPU COUPLED TEST 2.1 Objective of the Test The objective is to test the performances of the ALCATEL SPACE Thruster Module and the ALCATEL ETCA PPU during one firing sequence on each thruster / each cathode. 2.2 Test configuration One Thruster Module Flight Model (including 2 SPT100, 4 XFC and 2 FUs integrated on one Thruster Orientation Mechanism (TOM)) is placed inside a vacuum chamber and connected to 2 PPUs Flight Models. The test on each of the two Thruster Modules consists in performing 4 thruster firings (1 on each cathode) with the dedicated power supply, while performing a TOM actuation on a range of +/- 2.

8 One of the two Thruster Modules is a PFM and is submitted to a thermal balance and will be fully equipped with thermistors and thermocouples in order to correlate the Thruster Module thermal model. 2.3 Test Measurements During the test, the following parameters will be registered : Electrical parameters of the PPU and FU TOM position EMC measurements Performances of the Thermal Control of the Module. 2.4 Test Set-up The vacuum chamber included devices to simulate space thermal environment (in cold conditions) data acquisition and control PPU EGSE PPU 2 Test EGSE TOM EGSE XFC FU 2 XFC FU 1 TOM SPT100-2 SPT100-1 Vacuum Chamber Xenon Ground Support Storage PPU 1 Electrical harnesss Xenon tubing Management of test parameters Figure 8 : Thruster Module / PPU Coupled Test Set-up Figure 9 : Thruster Module inside the Vacuum Chamber

9 2.5 Conclusion on Thruster Module / PPU Coupled Test This test has allowed to verify the performances of the ALCATEL SPACE Thruster Module and to correlate the Thermal Model. It has also demonstrate a very good behavior of the Thruster Module and the PPU. 3. CONCLUSION During STENTOR and ASTRA1K programs system environment tests, ALCATEL SPACE has successfully performed performances and end-to-end tests of the Plasma Propulsion Subsystem integrated in the spacecraft. Unfortunately STENTOR and ASTRA1K will never reach their geostationary orbit, but all the qualification plan has been achieved and the ALCATEL SPACE Plasma Propulsion Subsystems have been formally accepted for flight by two major customers, the CNES with its expertise and SES with its strong commercial and industrial approach. ALCATEL SPACE has acquired a valuable experience and is now in a strong position to offer qualified Plasma Propulsion Subsystem onto its SPACEBUS family. Figure 10 : Photos of an ASTRA1K Thruster Module on Spacecraft

10 REFERENCES : [1] P.GARNERO, T.GRASSIN, A.JAMIN, I.JOUIN "Electric and Chemical propulsion at Alcatel Space" 3 rd propulsion conference on Spacecraft Propulsion, Cannes, France, October 2000 [2] X.RAGOT, N.MATTEI "Plasma propulsion subsystem life test-alcatel" 3 rd propulsion conference on Spacecraft Propulsion, Cannes, France, October 2000 [3] T. GRASSIN, L. BRIZE, O. DULAU, N. MATTEI, X. RAGOT "Plasma Propulsion Activities at ALCATEL" 36 th AIAA/ASME/SAE/ASEE Joint Propulsion Conference, Huntsville, Alabama USA, July 2000 [4] A.ROLFO, A. CADIOU, O. SECHERESSE, P. DUMAZERT, V.GOUNOT, X.RAGOT, N.MATTEI, T.GRASSIN "Plasma Thrusters Development in France" 52 nd International Astronautical Congress, Toulouse, France, Oct, 2001 [5] P. GARNERO "Satellite Propulsion Systems Needs in the Field of Equipment" AAAF, Aerospace energetic Equipment, Avignon, France, November 2002