AlM-94-2737 RUSSIAN EXPERIENCE OF EP A PL I CAT IO SPACE AND ON THE GROUND Alexander S.Bober *)I VIadimir Kim**), K.N. Kozubsky *), 6.Ya. Kofodny ***I, N.A. Maslenikov *), Alexey I.Morozov*'**), Vladimir A.Obu khov**), Gary A.Popov**), Yury P.Rylov*"***)

*) "Fakel" Design Bureau 181 Moskovskl prosp., Kaliningrad (obl), 236005, Russia Tel.: (01 1) 246-17-47, fax: (01 'I) 246-17-26

**) Research Institute of Applied Mechanics and Electrodynamics of Moscow Aviation Institute 4, Votokolamskae shosse, Moscow, 125871, Russia Tel: (095) 158-OO-20, fax: (095) 7 58-03-67

* **> 'I Po I y u s" Enterprize Moscow, Russia

****) I.V.Kurchatov institute of Atomic Energy PLKurchatova, Moscow, 123098, Russia

*****I All-Russlan Institute of Electrornechanics lstra of MOSCOW region, 443500, 'Russia

30th

June 27-29, 1994 / Indianapolis, IN Jr permisslon to copy or republish, contact the Amerlcan Institute of Aeronautics and Astronautics

'-370 L'Entant Promenade, S.W., Washington, D.C. 20024

RUSSIAN EXPERIENCE OF EP APBLlCATlON IN SPACE AND ON THE GROUND Alexander S.Bober *h VladimiP Kim**), K.N. Kozubsky *), G.Ya. Kolodny ***I,

N A , Mssbnikov *), Alexey LMorozov****), V l a W r A.Obuklnav**), Garry A.Popov**), -I

**e**) Yupy P.RyIov

*) "Fakel" Design Busenu 18 I Moskovski prosp., Kaliningrad (obl), 236005, Russia ?'el.: (01 I) 246-17-47, fax: (01 1) 246-17-26 Research Institute of Applied Mechanics and Electrodynamics of Moscow Aviation 4, Volokdamskoe shosse, Moscow, 125871 Russia

**) Institute

Td: (095) 158-00-20, fax: (095) 158-03-67

***) "Polyus" Enterprize MOSCOW, Russia

****) 1.V.Knrchatov Institute of Atomic Energy P1-Rnrchatova, MOSCOW, 123098, Russia

*****I All-Russian Institute of E1ectromech:hanics lstra of Moscow region, 143500, Russia

Abstract The experience of practical EP

application for the satellite orbit corrcction and attitude controI, as well as of the usage of ions and accelerated plasma flows sources on the EP basis for the reaIization of processes of vacuum ion-plasma technology is reviewed in the report. In particular, the efficiency is studied for solving the task of orbit parameters improvement up to the given afler the insertion into the orbit, the task of parameters correction and eccentricity variation for the satellite circular orbits and task of the satellite attitude control by EP using. In addition, the peculiarities of the propulsion set operation control while solwing the above mentioned tasks are presented as well as the test results for the propulsion set compatibility with other sateIli te s ys terns.

As EPs are highly efficient sources of accelerated plasma flows and charged particles, it is possible to develop the technologic sourccs on their basis for solving the tasks of vacuum ion-plasma technology. Examples of technologic tasks solution using plasma sources on the basis of SPT and ion sources, as well as compensated ion flows deceleration systems on the basis of systems with closed electron drift are in the report.

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I ntrodudion. Historical review As it's well known [1-6] considerable

successes in development and practical use of the electric propulsions (EP) in Russia have been achieved. They were based on great volume of research works, which have been realized in Russia and other republics of the former Soviet Union. And these efforts havc given a series of considerable results. Some of them will be considered below.

1. General information about flight tests and usage of EPS

The pulsed plasma truster (PPI) was the first EP deveIoped in the 1.V.Kurchatov Institute of Atomic Energy OAE) on base of which propulsion system (PS) with the PPT has been created and tested on the interplanetary spacecraft (SC) "Zond-2" in 1964 131. The pulsed plasma sources on the base of the PPT have been used many times as injectors of plasmoids during realization of the geophysical experiments 131.

The models of the ion thrusters (IT) of different designs have been realized and studied. In 1964-66, the first flight tests of the IT'S, as a part of the ionospheric laboratories, have been carried out [4]. At present time the works in this direction are connected with development of effective ion injectors for instaIlations of controlled thermo-nuclear fusion and space injectors of ions [s] and also

technological ion sources for ion-plasma treatment of surfaces in a vacuum.

-' The models of stationary End Hail Thrusters @HT) have been developed and studied. These Magnetoplasmadynamic trusters (MPT) with external magnetic fidd arc operating on alkali or alkaline earth metars with thrust efficiency of up to 30-40% at operation on lithium and powers of up to - 100 k W 161. High current MPT's with self induced magnetic field on litbiurtl are able to achieve the efliciency us to 60 % under specific impulse -6000 s and powers -300-500 kW [6]. Plasma sources on base of MPT including gas modifications had been used during rcalizstion of several geophysical experiments jn space 131.

The rcsuks of researches and development of the so-called Stationary Plasma Thrusters (SPT) with closed drift of electrons, which begun in the IAE under the leadership of professor A.I.Morozov, art: widely known [1,2]. These researches have been continued in the MA], the TsXAM, the MIREA, the NIlTP and other organizations, The Design Bureau "Fakel" has taken part since 1969 in development of the flight models of the SPTs and the propulsion systems on their base and over 60 units of the SPT had operated successfuify as parts of the regular systems of satellite orbits correction. By now thc production-type of SPT-70 thruster having thrust - 40 mN and power consumption - 0,7 k W has been qualified and is selled. The posterior production-type of SPT- IO0 thruster has been qualifcd under the Russian Standards and is being qualifyed according to western Standards by the joint Russian-American Company "Internationai Space Technology Inc" (ISTI) [7] Propulsion system with eight SPT-100 is operating now on board of Russian geostationary satellite "GALS" providing satellite station keeping in the North-South and East-West directions [SI.

In the Russia a very cIose to the SPT the thruster with so-called anode layer (TAL) had bccn developed and widely enough studied. These researches have begun in the TsNIlTMASH under leadership of A.V.Zhatinov and are continuing there at present time 191. The TAL i s also very close to the SPT by its performances, but has lower degrec of design development and qualification and was not tested in space.

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Extensive range of researches and developments had beeii realized for electrothermal trusters, namely resistojet ones (RJT) and arcjet ones (AJT). The practical result had been obtained from works on the RJT and by the present time the production- type of the thruster has been developed. It is able to provide thrust from 15 mN up to 1 N and l ie time up to 1OOOhours [l,Z]. In the orbit correction systems of the satellites of "Meteor" and "Metear-Priroda" type 40-ty of RJT have been operated successfully. Specific impulse of the thruster at operation on ammonia is 220-300 seconds depending on power consumption unexcelding 4 kW/N.

So, experience of Russian EP practical application is great enough. And some results of EP flight tests and usage will be considered below.

2. Main results of flight tests rand EP applications in space

In 1960 in the Soviet Union the program of electric propulsion (EP) and onboard power systems development and flight tests was formed. And mentioned EP flight tests were performed according to this program. During the preparation and tests the following tasks have been solved:

- Integration of electric propulsion systems (EPS) on board of Satellite. - Comparison of thruster performance received in Space and during ground tests.

- Confirmation of the EPS effectiveness as a satellite orbit correction and maneuvering system.

-Confirmation of the EPS reliability and thruster performance stability.

- Confhnation of SPT compatibility with other onboard satellite subsystems.

The first SPT flight tests were provided in 1972 [IO]. It was SPT-60 with outer diameter of accelerating channel of 60mm. Experimental propulsion system called "Eol- 1" (Fig. 1) consisted of 2 thrusters, propellant storage unit and control system, power processing and control unit (PPCU). The total mass of this PS was about 32 kg. The "Eol-I" PS was integrated serious on board of "Meteor" satellite without problems (Fig.2).

During these tests the thrust was measured using 2 methods: - By measurement of the rotation speed change operating in the satellite attitude control system due to the additiona! moment

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created by operating thruster with axis specially shifted relativc to the satellite center

- By measurement of the orbit parameter changes caused by operating thruster, Le,: it was possible to measure the satellite rotation period T change. The "Meteor" satellite orbit was close to circular with mean value of orbit height - 900 km. So, measuring the T magni- tude change AT it was possible to determine the thrust with accuracy -7%.

The measured thrust of SPT-60 was 17-20 mN [IO] and these values were close lo measured during ground tests - (20-2s)mN. The direerence of received results was possible to be exprained by difference of dynamic pressures in vacuum chambers (*1-2*10 4 Torr) and in Space as well as by interaction of thruster plume with the satellite solar panels.

The second task of the first flight tests was to demonstrate the possibility of the satellite orbit parameter change and satellite orbit height was changed by -17 km after operation of the thruster during -170 hours. Xn total PS "Eol- 1 " operated in Space for - 1 $0 hours and as a result of its operation the satellite orbit

-.. was transferred to convcntionally synchronous, when satellite is crossing equator in some (14 in our case) turns at the same points.

Tbird task was to check EPS compatibility with other subsystems of satellite. I t was found that under angles between solar panets and thruster axes less than 20" it was possible to register additional mechanical disturbing moments using control system telemetry signal. There was not found another significant impact of EPS operation upon other satellite subsystem operation. So it was confirmed that EPS is compatible with other meteor satellite systems.

The second EPS on base of SPT called "Eol-2" was tested on board of "Meteor- Priroda" satellite I1 11, having approximately the same orbit parameters, as "Metcor'l satellite. It was the prototype of EPS for "Meteor" type satellites orbit correction system on base of modified SPT-60 with the thruster level (-20 mN) and power consumption (-400 W). Main tasks of this tests were:

- To demonstrate the thruster performance

__ ofrnasscs,

A stability and EPS rcliability,

-To check more carefully the EPS compatibility with other sateilite subsystems.

- To demonstrate the sateUite maneuvering capabilities with usage of SPT.

The EPS "Eol-2" operated for - 600 hrs with 271 switchings during 27 months in orbit. The thruster perfomance was stable for whole period of operation and total thrust pulse -385 kNs was produced by EPS, having total mass -50 kg [I 11.

As a result of tests the satellite orbit was transferred to the synchronous type with accuracy of earth equator plane inter- section of -0,5 s, in several turns [I 31 allowing to fix satellite traces on the earth surface with accuracy of f I km. The possibility was demonstrated also reduce orbit excentrisity down to 5 *IO-4, to change satellite phase in orbit by 300.

The influence of SPT pIume interaction with solar panets during -300 hours was studied when the current density at the panel surface was estimated as -0,25 A h 2 (mean energy of ions -100 eV). The degradation of power production was close to the natural one in space.

Concerning the SPT operation influence on the operation of radio communication it was found that under close position of receiving on board antennae to thrustcr plume it was possible to loose some commands, But under their nominal mutual position no troubles have been found.

Thus the possibility to ensure high enough reliability and eflectiveness of EPS as orbit correction system, its compatibility with other subsystem were demonstrated. And after those tests all next EPS on base SPT operated in space as regular satellite subsystems for orbit correction. Some additionaI results were rcceived during tests of EPS "Eol-3" on base of SPT-50 having under power -400 W higher efficiency than SPT-60 [I 21. They confirmed all mentioned above conclusions,

As it was mentioned after successfull experiencs of the SPT usage the EPS on base of ammonia RJT was developed and tested on board of meteosats. Last ones allow to solve all orbit correction tasks, considered above, and atfitude controk tasks. And now EPS on base of RJT is used as a regular orbit correction system for meteosats.

On board of telecommunication geosta- tionary satellites EPS on base of SPT-70 with

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eWciency of -so%, specific impulse lsp 2 (I 500 - 1600)s and lifetime of -3000 hours, confirmed by ground life tests arc used since 1982 [13], And there were no problems with reliability and compatibility of EPS with other satellite subsystems 1141. These EPS were used for the satellite positioning in orbit and station keepind in the East-West direction. The statistical data show that maximum operating time of one thruster (out of four) was around 300 hours for this mission at (3-5) years OF satellite operation time.

Now the EPS on base of well known SPT-100 is operating on board of GALS geostationary satellite providing the satcllite positioning and full station keeping of this satellite.

So EPS are the regular part of Russian hydrometeorological and cornmunicatio satellites

3. Ground Application of ion and plasma sources developed 010 base sf EB.

Successfull EP development ensured the possibility of usage ion and plasma sources for ground applications and some of such sources has been developed and used in Russia. As in the West most extensive application have ion sources of different types in a microelectronics manufacturing procedures. They are used for the ion beam cleaning of subtrate surfaces, polishing and etching them, sputtering of different inaferiaks and deposition of sputtered particles, ion assisting of vapor deposition etc. During last decade there is increase of interest to the optical coatings received with usage of ion and plasma technology. And some samples of their successful1 usage will be indicated below,

One of them is multiiayer interference optical coatings are being widely used in the modern technology including optical instruments, cinema and photo equipment, space arid laser technology, scientific investigation, etc. Such coatings cover -90 percents of optical details (increase and decrease retlection of optical substrate surfaces, designed for sharing, polarization and filtration of light radiation).

Multilayer coatings consist of the consequence of films with high and low refraction index, including 1-70 Iaycrs on polished substrates made of optical transparent materials, such as glass, quartz, different artificial crystals. During Iast time

polymer and plastic lens, watersoluble crystals of LiIO,, LaCI, and others are being successfully covercd by optical coatings with usage of iodplasma technology.

Optical thickness of every film is usually has to be about part of wave length. Technological personal chooses the structure of coating, including a number and consequence of deposited layers, their refraction indexes and optical thicknesses. The important advantages of ion and plasma sources is good control characteristics allowing to reach high quality of such coatings.

Typical set-up for the multilayer coatings production on base of electron beam deposition equipment (Fig.3) consists of vacuum block, feeding sources and control system. Vacuum chamber is pumped out with the speed 8000-15000 liters per second. Thc plant could be supplied by 2 electron beam evaporators and if necessary by resistive evaporators, control calculation complex to produce deposition automatically 1151. Memory setup of control system permits for introduce the parameters of different cvaporation materials, technological processes and layer types for different materials, including a number of maximums in optical control, evaporation time, the value of the optical thickness layer, etc.

Interference method of optical thickness layers control during the deposition is applied.

The ion source on base of SPT i s very effective for the ion beam assisting of deposition processes @I. Existing experience showed that we could had low ion energy (100-200eV) and ion flux density 0,l-1,0 mA/cm 2 at distance 500 mm from the source exit plane. It was used successfulIy for receiving of hard coatings on polymers, polystird, water soluble crystals, etc without overheating of subtrates [lq. Main adventage of SPT type ion source is wide enough beam, allowing to treat many details simultaneously and to receive high quality of coatings due to low ion energies (- 100 eV). Additional advantages are as following:

- simplicity of their design and exploitation procedures;

- high enough life-time and reliability even when source is operating on active gases (for example on oxygen).

Ton source of Kaufmann type also have been used [8,15J. This type of ion source

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(diameter 100 mm) provides a great variations o f ion flux density (from 0,f W c m 2 to 10,O rntVcm2) depending from operating mode

,and distance between ion source and ion energy from0,2 toseveral keV and small divergence of beam (-IOo). It was used for two purposes: - Fer ion assisted deposition under electron beam evaporation.

- For deposition of metal or dielectric materials under pressure of Ar+O, in vacuum chamber - 1 * 10-4 Torr (Fig.4).

Advantage of such coatings is high refraction index, close to bulk of material, high hardness, good adhesion and gotnogeneus structure. Multilayer optical coatings, including films of TiO, and SO,, have low passive losses at wavelength 632 nm, equal 10-

To receive ion energies, lower than 200 cV it's possible to use together with ion source so called decelerators [l7ll .

So, thc technology developed in the field of the space electric propulsion activity are effectively used in ground technology,

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.- -I__. Conclusion

In total presented date is confirming the point that electric propulsion and ion and plasma sources on their base are now day technology in Russia. Their application were and arc giving really useful results.

Ref e ren ci es 1. Bober A.S., Kiln K, Komreev A S . ,

Morazov A.I., Popov G.A., Rylov Ju.P., Zhurin V.K State of Work on Electrical Thrusters in the Procecodings of 22 IEPC, Viareggb, Italy, 199 1.

2. Rylov Ju.P, Electropropulsion application history and tasks to be Solved on the spouccraft. Proceloiings of the seminar "Rocket propulsion technologies: Today and the Future". Moscow, MAT, November 7- 15, 1992, pp 275-285.

3, P o p G.A. State of electric propulsion development in Russia. Procccding of the seminar "Rocket propulsion technologies: Today and the Futul'c". MOSCOW, MA& November 7- 15, 1992, pp, 136- 179,

4. Grodzov-yky G.L., Nikitin V.E., Shot- tsov KV. The problem of spacecraft

interaction with ionospherc. In book: Physics and Application of plasma accelerators". Minsk, "Nauka i technika", 1974,pp,290-308 (In Russian).

5. Komvkin KN., Latyshev EA., Oh- khov V.A., Grygoran V.G. Research of ion thruster in the USSR. In the proceeding of 22 IEPC, volume 2, Viareggio, Italy, 1991, pp.Il .

6. Zhurin V. K, Popov G.A., Porotnikov A. A., Tichonov V.B., Utkin Ju.A. The state of research and development of end plasma thruster in the USSR. In proceeding of 22- IEPC, volume 2, Viareggio, Italy, 1991,

7. Golbert T., Day M., Fisher G., k7m K , Kozubsky K., Mastennikov N,, Randolph' T., Rogers W., Yen T. Plan and Status of the Development and Qualification Progmm for the Stationary Plasma Thruster. Ppaper AIAA-93- 1787.

8. Bober A., Kozubsky K, Kurnarov Q., Mmknnikov N.A., Kozlov A., Rommhk A. Development and Qualification Test of a SPT Electric Propulsion System for "GALS" Space Craft. Paper IEPC-93-008, PP.8-

9. Garkmha Kl., Lyapdrt EA., Semmkin A. V,, Tvsdokhlebov S.O. Anode layer thruster state of the art and problems - paper IEPS-

IO. Artsimovich L A . , el al. Development of the Stationary plasma thruster (SPT) and its test on "Meteor" Satellite. In yournal "Kosmicheskie issledovanij a", v .Xi I, N.3, 1974, pp.451-468 (Kn Russian).

11. Shsrernetyevsky N.N. et al. Main results of the electric propulsion systems with SPT in Space on hoard of "Meteor-prrirodd' satellite. In the book: VI all Union Conference on plasma accelerators and ion injectors". MOSCOW, VNTI "Center", 1978,

12, Sheremetyevsky N.N. et a!. Application of Electric propulsion system in the orbit' currectiun natural resources. In the book: TV allWnion conference on plasma accele- rators and ion injectors". - Moscow, WTX "Center", 1978, pp.324-325.

PP.6.

93-228, pp.8.

pp, 3 1 7-32 I .

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13. Arkhipov17.A. el ul. SPT electric propulsion system for Spacecraft Orbit Mansuering" Paper WGC-El? 92-07 in the baok: " 1-st Russian-German conference on electric propulsion Sigines w.nd Their Applications". Conference Proceedings". - Cicsen, 1992.

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14. Reshernev MI?, f??trWt?V~Gfa KK. Telecommunication Satellite Electric Thrusters Operational Experience" Paper RGC-EP 92-02 in the book" I -st Russian- German conference on electric propulsion engines and their Applications". Gicsen, 1992.

15. Kolodrry G. Ya. Interference muItilayer Optical Coatings for Orbital Instruments and Lasers. - Materials of "Seminar on Russian High Technologies Material Processing" Seou(, May lg-th, 1992, pp.13.

16. Schwicker H., Dui B., Kim V., et ul. Reactive ion-assisted deposition processes for interference coatings// IPAT Europe 8- th International Conference: Ion and plasma techniques) Brussd, May 1991,

17. Obukhov V.A. The system ion souce - ion decelerator for forming of dence beams of superlow encrgy ions. Proceedings of 10-th Internationat conference OR Gas Discharges and Their Applications. Swansea, 1992, Voi I , pp.502-505.

pp. 147-1 52.

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