Recent Progress in the USSR Electric Propulsion 88-004

V.V.Zhurin, A.S.Koroteev, A.A.Porotnikov, B..Roucervich

Academ- of Sciences, Moscow, USSR

Abstract.

Since 1971 in the USSR the stationary plasma thrusters ( SPT )

are continuing to be utilized successfully. The main problem here

for research scientists and engineers is to bring and verify thrus-

ters resource up to 7-10 ;years.

Together with SPT in the combined plasma jet unit of space

satellites and similar space apparatuses there is a significant

interest now for electrothermal or thermocatalitic thrusters which

have the lowest thrust pay ( just a few units of Watts for a gram

of thrust ).

New promising results are received with magneto-plasmadynamic

( MPD ) thrusters, which allow to have the flow velocities in an

order of value higher than in plasmatrons and the particles concen-

trations in an order of value higher than it in any other stationa-

ry accelerators. They are used widely in geophysical investigations,

on satellites, for ballistic experiments and became indispensable

in the technology of implantation of deposited material in a lining.

In these areas the pulsed plasma thrusters ( PPT ), which are

actually MPD thrusters, can be considered as equal partners.

The rIIPD thrusters could be honoured to become the main perfor-

mers for realizing the widely discussed recently international

flight project to the Mars.

Starting 1971 the stationary plasma thrusters - SPT are con-

tinuing to be exploited successfully with "Meteor" type satellites

/ 1,2 /. Let us remind its scheme ( Pig 1 ). At the level of con-

sumed electrical energy about 0.5 kWt they create the thrust aro-

und 2 grams with specific impulse 2000 sec when working material

is Xenon.

The system of collection and processing of measured informa-

tion requires the transfer from a single satellite at conditional-

ly synchronous orbit ( satellite's passing of fixed region after

some given time or after a definite number of turns ) to the sys-

tem of satellites from average height up to geostationary orbits

/ 3 /.

37

The utilization of EPS ( Electric Propulsion System ) solves

the problem of development of similar space systems, providing

the change or the stabilization of satellites relative placing in

the system. The time of active functioning of EPS must be up to

7 - 10 years and must be verified by ground laboratory tests, in-

spite of relatively difficult "heavy" shortened tests. It is clear

that the real "firing" resource is less than the required time

( 7-10 years ), but thruster must be ready to the next switching

on. The summary impulse of EPS reaches several millions of !ew-

ton-seconds, and the thrust of EPS as the correction executing

system has tenths fraction of Uewton. The space apparatus energy

capability composes Kilowatts of energy and will be increasing

with time.

The thrust unsteadiness of EPS caused by shortened time of

initial correction and increasing of accuracy of satellite corre-

cting maneuvers, must be no more than 3-5% .The SPT dynamic cha-

racteristics, in particular, the activation time and after action

time are determined by the requirement of operativity increase

and must be no more than is and 0.3-1 Ns, correspondingly. The

number of SPT switchings is required on a level of 10 -105 .

Together with SPT in combined EPS there is considerable

interest to thermoelectrical or thermocatclitic thrusters working

on hydrazine and ammonia, having the lowest thrust price ( units

of Watts for 1gram of thrust ).

The new promising results were received with IiPD ( butt-end )

accelerators, allowing to reach the plasma flow velocity in order

of value higher than in plasmatrons or in electrothermal thrusters;

also here particles concentrations are higher in order of value

than in other stationary plasma accelerators. These high characte-

ristics and pulsed plasma accelerators, which are in fact LIPD-acce-

lerators, allow to utilize them extensively in geographical studies

on satellites and in ballistic experiments. The main problems which

are solving here : physics of space plasma, investigation of struc-

ture and dynamics of artificial plasma creations in ionosphere,

investigation of -shock waves, plasma instabilities, induced stimu-

lation of substorm phenomena, stimulated precipitation of captured

particles, excitation of artificial luminescence of ionosphere, its

38

conductivity and so on.

The detailed analysis of results is published regulerily in

Soviet periodical scientific journals.

Let us give a small Table of most characteristic parameters

of utilized Soviet accelerators / 4 / :

Table 1

N Type of '.:orking Fl3w Power,accelerator material rate Energy

Stationary Plasma Accelerators

1 SPT Xe 10-3g/s 500 it

2 MPD K 10-3g/s 2.5 kIit

3 MIPD Air (1-3)10-3g/s 3 kWt

4 IPD Cs 0.3 g/s 4 kWt

5 MvPD Li 0.15g/s 15 k; t

Pulsed Plasma Accelerators

6 PPT BaC12 1017 particles 100j

7 PPT C2F4 1018 particles 600j

8 PPT C2 F4 1019 particles 1400j

The technological plasma accelerators discover quite a broad

use in industrial applications, From the first industrial instal-

lations "Bulat", "Pusk", till appearance of modern advanced inst-

allations the different collection of means is accumulated for

plating special covers and films, implantation and cementation,

introduction into materials different other materials, creation

of atomically pure surfaces, growing of different crystals and so

on. The utilization of plasma accelerators provides the uniformi-

ty in width, the absence of porousity, the good adhesion with

backing, the stability in time of perfoming characteristics, the

mechanical strength, the thermal stability, the absence of impu-

rities in pure metals films and conservation of stoichiometry

composition in films of complex composition. One of new technology

first users became the instrumentation industry because they found

excellent proof of increasing in oder of value and more of instru-

ment's wear resistance.

In the microelectronics ( production of integral schemes and

theirs elements ), in the tensoprobes production, in the supercon-

ductivity technics, in the optical instruments production and other

39

spheres of technics the thin films of different types - conducting

and dielectric, films of different composition found a very good

application.

Few words on IMarsian Program.

Now two space apparatuses "Fobos" are moving to Mars, in 1994

we expect to have there Marsian Balloons and Liars Vehicle, in

1998 the Marsian soil is planned to be returned to Earth and what

else, we are waiting for preparations for Mars expedition ( by the

way the expedition was discussed during recent Moscow meeting of

two leaders M.Gorbachev and R.Reygan ).

In recent article by acad.V.P.Glushko et al. presented the

following initial data for one year and half flight to Mars: for

the start from the low Earth orbit of space ship using the chemical

th'u.sters the initial mass of space ship will be 2500 tons, in case

of nuclear thrusters with direct heating of working material, it

will be 800 tons, but with nuclear electric propulsion - only 450

tons ( Fig 2 ). Let us remind, that the useful loading, which can

be transfered into near Earth orbit by rocket-carrier "Energia"

( after it modification ), will bo 200 tons.

Even providing the acceleration in 10 4g the summary EPS thrust

will be 45 kg ( 450 N ). It is clear that such propulsion system

must be developed according to the module scheme. This is important

factor for EPS reliability increase and for simplification of pro-

cessing of each module unit.

At the characteristic resource of EPS in 10' hours and working

material flow velocities up to 107 cm/s we can have the summary

power in tens of Megaatts.

As example of stationary high current MPD accelerator would

be the thruster with Bismuth liquid-metallic cathode, shown in

Fig 3. By the direct accelerators thrust and by the measurement

of material flow the velocity plasma flow was determined and

reached ( 4-6.5 ) 106 cm/s. At power supply voltage in 50-100 v

the disharge current was 3-8 kA.

At common low voltage power sources placed on board of space

apparatus such thrusters can be combined with them without any

additional converters of high voltage in tens of .egaWatts.

40

As we could see from this brief review all mentioned develop-

ments in electric accelerators today already give very interesting

results and later we expect much more.

It is worth to mention that in our country the regular USSR

Conferences on Plasma Accelerators and Ion Injectors are continuing

to have place.The last one was held in Dnepropetrovsk, September

16 - 18, 1986. About 160 papers were presented. The Conference

showed more deep theoretical understanding of working processes

and their's erperimental support as in classical schemes of accele-

rators and a necessity for search of new schemes with new physical

problems. For example, the group scientists, headed by Dr.V.E.For-

tov / 5 /, studied the acceleration regimes of dielectric materi-

als ( in particular, polycarbonate with mass about 1g ) and dynamics

of plasma piston in the rail-type accelerator. It is shown that in

such accelerator with length of electrodes about 1m the velocity

can be reached up to 6km/s.

In order to give an impression on type of problems which were

of main interest at last Soviet Conference, let us tgive the titles

of 8 sections and a number of papers presented :

1. The accelerators with anode layer - 10 papers

2. The accelerators with closed drift of

electrons and extended zone of acceleration - 28 papers

3. The ion and plasma-optical systems - 29 papers

4. The systems for plasma accelerators and

ion sources - 14 papers

5. The high current plasma accelerators - 26 papers

6. The diagnostic methods - 10 papers

7.The numerical modelling - 15 papers

8. The applications of plasma accelerators in

science and technology - 25 papers

References

1. V.V.Zhurin, A.A.Porotnikov, V.P.Shadov, "Electric Propulsion

Research and Development in the USSR", AIAA paper, 76-1073

2. A.I.Morozov, "Physical Foundations of Space Electric Thrusters",

v1, Atomizdat, Lioscow, 1978 ( in Russian )

41

3. E.V.Iitusov, V.P.Khodnenko, "Perspectives of SPT Utilization

for Meteorologic Space Systems Orbit Corrections", VIth Soviet

Conference "Plasma Accelerators and Ion Injectors", Dnepropet-

rovsk, Sept 16-18, 1986 ( in Russian )

4. S.I.Avdjushin et al, "Utilization of Plasma Accelerators for

Study the Physical Processes in Space", in Proceedings "Plasma

Accelerators and Ion Injectors", Iauka, Iloccow, 1984 ( in Russianl

5. MI.MI.Kondratenko et al, "Regimes of Dielectric IMaterials Accele-

ration and Dynamics of Plasma Piston in Rail-Type Accelerator",

Vth Soviet Conference "Plasma Accelerators and Ion Injectors",

Dnepropetrovsk, Sept 16-18, 1986, ( in Russian )

42

Fig.1 Accelerator with closed driftand extended zone of acceleration1 - anode - gas distributor2 - dielectric walls3 - cathode neutralizer4 - working material supply - Xe

12 34

Fig.2 Electric Propulsion System ( EPS )with nuclear reactor-generator :1 - reactor-generator2 - shield3 - converter of electric energy4 - EPS5 - radiator- cooler6 - room for equipment7 - useful loading

43

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Fig.3 High current accelerator withliquid metal cathode1 - centrfugal injector for liquid Bi2 - conical cathode3 - collector4 - isolator5 - anode

44

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