Overview of Electric Propulsion Activities in Russia

The paper provides a review of major activities in the Russian industry and research organizations in a field of research, development and application of Electric Propulsion. Leading spacecraft manufacturers in Russia NPO PM (Krasnoyarsk), Rocket Corporation “Energiya” (Korolev city), Khrunichev Space Center (Moscow), VNIIEM (Moscow) continue successful EP application on GEO and LEO spacecrafts. Design Bureau “Arsenal” (Saint Petersburg) and NPO Mash (Reutov city) plan to use EP on their satellites. Growing EP application generates new requirements to the parameters of the propulsion systems and stimulates development and research activity at EDB “Fakel”, RIAME, TsNIIMASH, MIREA, Keldysh Research Center. For Hall thrusters the main directions of these activities are to expand operation range in regard to specific impulse, thrust and power. Several thruster schemes are under evaluation – one stage SPT and TAL, two stages SPT and TAL. For low power propulsion systems PPT and low power Hall systems are under consideration. EP application is supported by permanently improving computer modeling necessary for calculation of different plasma effects accompanying EP operation onboard of a spacecraft (SC). Space experiments on the International Space Station are undergoing in support of verification and improvement of the computer codes and physical models. Introduction The paper presents joined materials contributed by leading Russian spacecraft manufacturers using different types of electric propulsion (EP), as well as organizations dealing with research, design and production of EP systems, thrusters and plasma devices. * Deputy Head of Division, Head of Electric Propulsion Laboratory, avs@tse.ru Scientific and Production Association of Applied Mechanic (NPO PM, Krasnoyarsk) Application of electric propulsion at NPO PM has been started by launch of spacecraft (SC) “Potok” May 18, 1982. Four stationary plasma thrusters SPT-70 have been used for north-south and east-west orbit correction. In total 15 SC of Potok and Luch series with 4 SPT-70 onboard of each one have been launched in 1982...1999 year time frame. In 1994 first SC Gals with SPT -100 developed by EDB “Fakel” has been successfully launched. Since 1994 11 SC of GALS, EXPRESS and SESAT series have been equipped by SPT-100 thrusters using Xenon as a propellant. For the first EXPRESS and GALS satellites the propellant mass was one of the key parameters limiting SC design lifetime. Mass of xenon carried in the SC tanks for the first EXPRESS and GALS satellites was selected based on 5-year lifetime design requirement. But later on an experience obtained during exploitation of these SC allowed to improve the algorithms of EP system operation and minimize the EP firing time. That. In turn, allowed to expand SC lifetime up to 7 year. Last satellites EXPRESS series have 12.5 year lifetime. It should be note, that progress in SC lifetime has been achieved taking into account detailed study of interaction between EP and SC subsystems. Interaction and potential influence of SPT thrusters and plasma plumes on a SC always are in a focus of NPO PM efforts during development and exploitation of EP onboard their satellites. Special measurements performed during operation of all satellites allowed to get proven data and verify computer model developed in MAI for calculation of plasma beam interaction with solar panels and corresponding appearance of mechanical torques. Two spacecrafts namely EXPRESS-#2 and #3 launched in 2003 have been equipped by set of probes to measure parameters of plasma flow generating by EP thrusters. These probes allow to measure ion energy and flow density. Two probes were installed near satellite payload and another two one were attached to solar arrays. The arrays rotate relatively to SC and EP thrusters, and attached probes provide data about angular distribution of the plasma beam parameters. Besides that, measurements of electric field in several points on a surface of EXPRESS-A #2 and #3 has been performed without and with EP operation. For future programs NPO PM considers several potential EP manufactures and supports several activities aimed on development of a Hall thruster with specific impulse (Isp) higher than one for modern SPT-100. New thruster KM-5 (T-120) developed by Keldysh Research Center now is in use onboard of EXPRESS-A4 for northsouth correction. Higher Isp will allow to minimize mass of xenon propellant for satellites with increased lifetime. Next generation of thrusters with improved and expanded range of operating parameters are now under development at EDB “Fakel”, Keldysh Research Center and TsNIIMASH in accordance with NPO PM specification. POTOK spacecraft EXPRESS AM satellite Figure 1. General view of POTOK and EXPRESS AM spacecrafts [] The 30 International Electric Propulsion Conference, Florence, Italy September 17-20, 2007 2 All-Russia Scientific and Research Institute of Electro-Mechanic (VNIIEM) Scientific and production enterprise VNIIEM is actually the first SC manufacturer in the world tested SPT-type thrusters (EOL-1) in space onboard of METEOR satellite in 1972 ]. The successful flight tests were performed in 1974...1976 and provided unique database and knowledge in regard to EP system parameters, compatibility with SC subsystems, optimized algorithms of low thrust systems operation. The total accumulated firing time of the EP system was about 1000 hour, and it is important to note, that no failures or incorrect operation of the system were observed. Exploitation of the SPT thrusters was combined with unique research program performed with help of scientific probes installed on the SC []. Most remarkable results of this study can be summarized as following: 1) variation of the spacecraft own atmosphere was identified during operation of EP system – density of the particles reached up to 10 cm (for orbit 900 km), ion energy = up to 30 eV, and SC floating potential was about 10 V. 2) there is a dependence of the plume propagation on its orientation relatively to Earth magnetic field, 3) electromagnetic emission with frequency ranges 5...20 kHz and 0,8...1,5 MHz accompanying the EP system operation were found; 4) mechanical torque from plasma beam impinging solar arrays was identified and measured for different relative orientation of the beam and the solar panels, 5) no degradation of the solar arrays output characteristics were found, and survivability of the arrays under interaction with plasma beam was demonstrated. After successful tests of SPT a new GEO meteorological SC “ELECTRO” utilizing monopropellant ammonia resistojet has been developed at VNIIEM. The satellite has been launched and successfully operated in a period 1988...1994. The used ammonia thrusters are able to provide thrust 0,15 N and total impulse 130 Ns, EP system consisted of 12 thrusters and provided orbit correction and orientation of the SC. Important aspects of the SC own atmosphere variations, potential condensation of the product from jet exhaust plume were studied. As a result of flight tests of different EP systems possibility of their application has been proven. Now VNIIEM is under design process of a new small Earth observing satellite KANOPUS with low power SPT onboard. General view of the SC is shown on the Figure 2. Specific of the satellite and propulsion system is the operation at 200 W only. Propulsion system based on SPT-50 type thruster from EDB “Fakel” has been selected for this mission. The propulsion system has to provide orbit correction, maneuvering and SC orientation with total impulse 50 000 Ns. Thruster block with two SPT is designed to perform all mentioned functions, it is intended to provide thrust vector control by variation of SC orientation.