Thales Alenia Space Experience on Plasma Propulsion
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Thales Alenia Space Experience on Plasma Propulsion IEPC-2007-301 Presented at the 30th International Electric Propulsion Conference, Florence, Italy September 17-20, 2007 Michel LYSZYK* and Laurent LECARDONNEL.† Thales Alenia Space, Cannes, 06150, France Abstract: Thales Alenia Space experience on plasma propulsion has been developed in the frame of Stentor, Astra 1K and GEI programs with plasma propulsion systems using SPT100 thrusters manufactured by Fakel and commercialized by Snecma . The PPS (plasma propulsion system) use in house equipments such as Power Processing Unit (PPU) manufactured by TAS-ETCA in Charleroi and the Thruster Orientation Mechanism (TOM) manufactured by TAS-France in Cannes . The PPS subsystem is used on board our SpaceBus satellite family to perform North-South station keeping. The on going activity on the XPS (Xenon Propulsion System) is devoted to the next European platform Alphabus currently under joint development by Thales Alenia Space and Astrium with CNES and ESA support. The XPS uses also the PPU manufactured by TAS-ETCA , the TOM manufactured by TAS-France and the Xe tank developed by TAS-Italy ; it use also the PPS1350 thruster under qualification by Snecma , a xenon regulator and a latch valve under development at Marotta Ireland. I. Introduction HIS document describes the Thales Alenia Space experience gained through Stentor , Astra 1K , GEI, T Spacebus and Alphabus programs on plasma Hall effect thrusters propulsion subsystems . For Spacebus application a description of the subsystem is given together with the general achieved performances . For Alphabus application a general status of the on going activities is given . * Head of electric propulsion section, Propulsion Department, [email protected]. † Head of propulsion department, Propulsion Department , [email protected] . 1 The 30th International Electric Propulsion Conference, Florence, Italy September 17-20, 2007 Thales Alenia Space Experience on Plasma Propulsion ..................................................................1 I. Introduction ...........................................................................................................................1 II. SpaceBus Plasma Propulsion Subsystem.................................................................................3 III. PPS DESCRIPTION...........................................................................................................4 A. GAS MODULE ...............................................................................................................4 B. PLASMA THRUSTER MODULES.................................................................................5 C. POWER PROCESSING UNIT........................................................................................6 D. LAYOUT ........................................................................................................................6 E. KEY FEATURES............................................................................................................7 IV. Stentor application..............................................................................................................7 F. PROPULSION SYSTEM DESIGN .....................................................................................8 G. Satellite Assembly Integration and Tests Flow chart ........................................................9 H. Synthesis of Stentor ground qualification experience .......................................................9 V. ASTRA 1K application .....................................................................................................10 I. SPT100 Cold Starts...........................................................................................................11 J. Thruster Module / PPU Coupled Test: ..............................................................................11 VI. ALPHABUS application....................................................................................................12 VII. Conclusion ........................................................................................................................13 Acknowledgments........................................................................................................................13 References ...................................................................................................................................13 2 The 30th International Electric Propulsion Conference, Florence, Italy September 17-20, 2007 II. SpaceBus Plasma Propulsion Subsystem The function of the Plasma Propulsion Subsystem is to provide inclination and eccentricity control for North/South station keeping and in addition it allows unloading of reaction wheels. For SPACEBUS platform, the technology retained is based on the use of SPT 100 thrusters which offer an in- orbit great experience as they have been flying since beginning of 1994 on GALS satellites in Russia. They also offer great advantage because of their good compromise between a good specific impulse (1510 s), a high thrust level (80mN) and a decent-sized electrical power needs in comparison with the other electrical thrusters. The Plasma Propulsion Subsystem uses Xenon as propellant. It includes all devices to store and supply Xenon to the electrical thrusters, four Stationary Plasma Thrusters (SPT100) which are accommodated by pairs on two orientation mechanisms, electronic units required to manage and provide power to the thrusters and the orientation mechanisms. As shown in the following Figure , the PPS can be divided in three main parts : · The Gas Module (GM) · The Power Processing Unit (PPU), which includes one Thruster Selection Unit (TSU). Two PPU are provided, one nominal and one redundant. · The Thruster Module (TM), with two SPT’s and associated Xenon Flow Controller (XFC), an orientation mechanism bearing and canting the SPT’s. Two thruster modules are provided, one for the North maneuvers and one for the South maneuvers, each one including a nominal and a redundant thruster. The North (resp. South) module is implemented on the anti-earth face on the north (resp. south) face of the satellite and is used for South (resp. North) Station keeping maneuvers. Figures 1 : STENTOR AND ASTRA 1K GAS MODULE INTEGRATED ON JIG 3 The 30th International Electric Propulsion Conference, Florence, Italy September 17-20, 2007 Figure 2 : ASTRA1K PPS GAS MODULE ON THE SATELLITE III. PPS DESCRIPTION A. GAS MODULE The Gas Module is required to store Xenon and isolate the Xenon storage from the Plasma thrusters during prelaunch, launch and orbit raising phases in safe conditions. During on-orbit phase, it will then supply Xenon to the Thruster Modules at the required regulated pressure and cleanliness level. The Plasma Gas Module includes the following equipments : · two Xenon tank to store Xenon up to 150 bar, · a high pressure fill and drain valve to pressurize the tanks, · a normally closed pyro valve isolating the storage volume during ground integration activities and launch, · two high pressure transducers for Xenon gauging, · associated titanium feed lines (1/4” diameter). · Three fill and drain valves located upstream and downstream the pressure regulator. These valves are used for ground tests, · two valves in parallel in order to provide isolation of the distribution assembly in case of abnormal external leakage, · a filter in order to protect all the downstream components of any abnormal particulate cleanliness, · a mechanical pressure regulator which is fully series redundant. Each stage is capable of delivering Xenon at a regulated pressure to the thruster module over the complete range of temperature, inlet pressure and flow rate during thruster operation and it provides leak tightness between two thruster operations. · two low pressure transducers used to tightly monitored the level of the regulated pressure at the outlet of the pressure regulator. · titanium feed lines up to the thruster modules and titanium-stainless steel connection which ensure leak- tightness of the subsystem as a whole and minimizes mass. The arrangement of the high pressure transducers (upstream) and of the low pressure transducers (downstream) provide a full redundancy and allows to measure: 4 The 30th International Electric Propulsion Conference, Florence, Italy September 17-20, 2007 · the pressures in the tanks and in the feed lines for general monitoring. · the pressure delivered by the pressure regulator for general monitoring. · the pressure accumulated downstream of the pressure regulator in worst case of leakage (if any) to prevent over pressure. · the pressure conditions at the XFC inlet for general monitoring. · the needed measured pressures for propellant gauging purposes. The PGM is kept clear of any liquid Xenon. The Thermal Control Subsystem (TCS) provides thermistors and heaters to control accurately the Xenon temperatures and state inside the tank and at the puppet level of the pressure regulator. B. PLASMA THRUSTER MODULES Each Thruster Module consists of the following elements: · Two SPT-100 plasma thrusters, one nominal and one redundant, · Two Xenon Flow Controllers (XFC) associated to each thruster. Each XFC are feeding each the cathode and the anode and providing by the way redundancy. The XFC includes a thermo throttle which allows to control the Xenon mass flow-rate. · Two Filter Unit (FU). The filter unit is located upstream each SPT in order to limit electromagnetic conduction