Adv. Space Roe. Vol. I, pp. 129—140. 0273—117]/81/02U1—0129$05.00/O~k10SPAR, 1981. Printed in Great Britain.

EXPERIMENTS WITH INJECTIONOF POWERFUL PLASMA JET INTOTHE IONOSPHERE

R. Z. Sagdeev,*G. 0. Managadze,*A. A. Martinson,Yu. A. Romanovsky,** R. I. Moisya,*****W. K. Riedler,*** M. F. Friedrich,***T. G. Adeishvily,**** S. B. Lyakhov,*L. S. Novikov,** N. A. Leonov,***** T. I. Gagua*andI. I. Slyusarenko*****

*SpaceResearchInstitute, USSRsslnstituteofApplied Geophysics,USSR

***Institute of Communicationsand WavePropagation,

Austria* **A bastumanyAstrophysicalObservatory,Georgian

AcademyofSciences,USSR** ***Kiev StateUniversity, USSR

ABSTRACT

This paper describes two rocket experiments “Aelita” with high po-

wer lithium plasma injection. The results of onboard magnetometer,

massepectrometer, photometer, plasma, corpuscular and ground radar

measurements are given. Dynamics and structure of plasma formation

are discussed.

EXPERIMENT DESCRIPTION

To study the features of the 3truoture and dynamics of the power-

ful plasma jet as well as perturbations of the electrical and mag—

netic fields due to the plasma injection two experiments in theframework of the AELITA program were carried out where the injecti-

on of the powerful plasma jets was performed from a MR—12rocket

at heights 100 to 145 km. The data on the experiments are given in

Table 1.

129

130 R.Z. Sagdeev et al-.

TABLE 1 AELITA Experiments Data

Experiment Date LT Solar K Pitch— Commentsdepression ~ angle ofdegrees’ injection

Aelita 1 6.X.78 5.55 11’ 1 9O~-15O ~o sepa—(AL—i) + ration

Aelita 2 25.X.79 0.005 2_ 66~-114° Separation(AL—2) of plasma

gun

Both experiments used a stationary plasma accelerator of the end—

—type [iJ with the following parameters: a propulsive mass—lithi-

um, ion current — 300 A,jet velocity up to 10 km s1, ion ener-

gy — 4 * 10 eV, angular divergence of the jet ±10°, jet density

at the injector cross—section — 1014 cm3, Te = 2.3 eV. During

the AELITA (AL—i) experiment the injection was made into the upper

hemisphere with pitch—angles 90.150°, during AELITA—2 (AL—2) with

pitch—angles 66+114°. In the AL—2 experiment the accelerator was

separated from the rocket with a velocity of 3.5 m s~ being in a

stable position. The plasma was injected in continuous and discrete

modes.

To analyze the artificial plasma formation (APP) and the effects

of perturbations in the ionosphere the rocket was equipped with the

following instruments: probes for measuring Te and ~Le~as ion p~o—

be for m8asuring Zi1,. and E1, photometers for emission at 6300 A

and 6708A, a three—component magnetometer, a detector of the elec-

trical field, Geiger counters for measuring fluxes of electrons

with E>40 key, mass—spectrometers, a spectroanalyzer of lithium

ions.

To analyze APP by means of radlooccultation the records of a car-

rier—frequency amplitude from the on—board telemetry transmitter

were analyzed. In addition, to study the structure and dynamics

of APP in the ionosphere the data from the meteor radar {2)

working at two frequencies: f1=22.5 and f2—33.8 MHz (

2.f and ~ =

=13.3 and 8.7 m, respectively) were used. Radiolocation was per-

formed within the angle of aspect, i.e. the radar beam was perpen-

dicular to a magnetic field vector in the radiolocation region.

Plasma Jet Injection into Ionosphere 131

EXPEI~Il:~ENTAL RESULTS

Fig.1 presents the pulse sequence of the plasma injection in the

first experiment as well as the APP radar data

50 100 150 200 250 300

Pig.i. Data on the rocket trajectory and the APP radio—

location at two frequencies for the continuous

() and discrete (———) injections of the plas-

ma; — injection of neutral lithium, h is

the trajectory altitude (kin) 0 is the effective

cross—section of APP scattering at frequencies

f1=22.5 and f2=33.8 L~Hz (rn2).

The values of the effective cross—sections of scattering ~ for

waves ~ and 212 averaged over 1 s are given to which the critical

values of 1e equal to 6.3 x io6 crn3 and 1.4x107 cm3 correspond.

Fig.1 shows that APP occurs at once after the plasma jet injection

and persists during the injection. The values of C’ and APP—di-

mensions increase by 1.5 to 2.0 times with the rocket ascending.

The maximum dimensions of APP adequate to the critical levels of

and n~ are: L1=1 kin and L2=0.5 km.

According to the mass—spectrometer data the energy of lithium ions

measured reaches 5.10 eV which agrees with the data of ions ener—

gy measurements in the laboratory.

The density distribution in the plasma jet obtained from the data

of the direct and radar measurements is shown in Fig.2.

132 R.Z. Sagdeevet al.

~.

x probes

~radar

- ~.c:~:‘~‘‘I jo2

Fig.2. Density distribution in the plasma jet:

points — experiment; the curve — model, Ne — a

density of plasma (cm3); L — distance from theaccelerator (m).

Synchronous enhancements of signals from the probes as well as

from the photometer were observed at 160 and 190 s of the flight

when the distance between the accelerator and the rocket was -~5Om

and~’15O m, respectively. The maximum distance at which the opti-.

cal emission associated with the plasma injection was recorded was

about 600 m. Pig. 2 also gives the model distribution of the plas-

ma density calculated in accordance with • The agreement

between the experimental data and the model is observed in the

rocket vicinity. At larger distances the model density values des—

crease more than the experimental data.

The peculiarities in the plasma density variations near the rocket

with the accelerator switched on and off are shown in Pig.3 based

on the radar and probes data in the AL—i experiment.

On injecting the jet the local density of the plasma is 5x109 to

5x101° cm3 at a distance of 0.7 in from the rocket. When the in—

section stops the local density of the plasma decreases sharplyto ne=(345)xi07 cm3. This effect duration changes from 0.1 to

0.2 s at 110 to 120 km and up to 0.3 to 0.4 a at 140 km.

The peculiarities of the structure and dynamics of the APP develop-.

ment during the plasma injection and after, it manifest themselves

clearly in the process of the plasma cloud radiolocation. Fig.3

also shows the data on the amplitude arid phase characteristics of

Plasma Jet Injection into Ionosphere 133

~l~~- ~

A1~l

U~~

~~J~LJJ((

.

~ 2pO2CJls

Pig.3. Variations of the local density of the

plasma during the jet injection. The amplitude U1,U2 and phase ~, ~characteristics of a radar sig-

nal from APP, the amplitude characteristic of

a carrier frequency of the on—board telemetry du-

ring the plasma accelerator operation. Vertical

bars correspond to the appearance of the plasma

Irthomogeneities in APP. The dotted line shows

reflections from the natural radiometeor. The

shadowed band illustrates the period of the plas-ma injection. T is the launch time in seconds,

Ne — a local density of plasma in cm3.

a radar signal to compare them with the results of direct measure-

ments of the plasma density.

The “suiuoth” reflected signal U1 and U2 at two frequeucies of the

radar corresponds to the plasma injection periods that indicates

to the relative homogeneity of APP at different levels of the plas-

ma density. The velocity of the reflecting surface of APP moving

across the magnetic field (along the radar beam) determined from

phase characteristics are 200 to 300 m s~. It means that the pe-

ripheral part of APP from which radiowaves ere reflected at fre-

quencies f1 and f2 is almost retarded. When the plasma injection

134 R.Z. Sagdeevat al.

stops the radar signal becomes finely structured which indicates

the appearance of plasma inhomogeneities in APP which form many

scattering centres. The plasma density decrease is followed by

the transition from the monochromatic spectrum of phases $ andto quasi—noise type which is observed during Q2 to 0.4 sec af-

ter the injection has stopped. This pass shows that with the acce-

lerator switched off the APP motion changes, i.e. instead of direc-

tional it becomes random. The occurrence of the plasma inhomoge—

neities is also confirmed by the appearance of a modulation of the

on—board transmitter signal amplitude that is also shown in Fig.3.

To compare the natural and artificial plasma formations in the io-

nosphere Fig. 3 gives the amplitude and phase characteristics of

a signal from the natural radiometeor recorded in the experiment.

The significant local perturbations of the magnetic field occur

during the plasma jet injection in the rocket vicinity as follows

from the records of the magnetometer deployed on the boom 1 m away

from the rocket. It is seen in Fig. 4 where the data recorded from

different components of the magnetometer are shown (in the AL-i

experiment)

‘The amplitudes of signals over “÷X” and “—Y” — channels decrease

during the injection arid the amplitudes over “—X” and ~+Y~ — chan-

nels increase; the value of these effects reaches ~H~-(3 to 5)x

x103 gammas. It should be noted that during the plasma injection

the inversion of “+Z”—signal fron~the magnetometeris observed

which is coherently modulated with “—Z”—signal of the spinning

rocket. When the injection stops the levels of signals over TT+X~~

and “+Y” channel as well as the antiphase character of modulation

of signals above ~ and “—Z”—channels appropriate to the undi-

sturbed conditions are recovered during 0.1 to 0.5 a (depending

on height).

The results of magnetometer measurements in both experiments in-

dicate that the dimension of a diamagnetic cavity, the formationof which is possible due to pushing out the magnetic field by the

plasma [3,4J,canno’t exceed 1 m under the experimental conditions.

In the second experiment the local disturbances of the magnetic

Plasma Jet Injection into Ionosphere 135

:#he: a~pe~fma~nth,rn~#e~r AL-I

:tA :4/4%—~ -

~ _________

.4 . . . -

:Ay-y~ ~f:

~~_j~•• ~ ‘~:~~- ~

123 125 12? ~

Fig.4. Records of signal a~nplitudesover channels: ±X,

±Y~+Z of the magnetometerwhen the plasma accelera-tor operated under the conditions .appropriate to

Fig.2 in the AL-i experiment. Each of ~X and ±~channels covers 5x104 gammas and of +Z channel —5x103 gaimnas. The value of 1~Hshows the changes

in appropriate channels due to the plasma injec-

tion. Signal amplitudes over ±X, ±Yand ±Zchan-

nels are modulated because of the rocket spin.

field up to several hundreds of gammaswere observed at distances

50 in from the plasma injection with the enhancements of the plasmadensity seen in Pig. 2. In other regions of the plasma jet the per-

turbations of the magnetic field, if they were present, did not

exceed.~H”300 gammas.

To illustrate the peculiarities of the electrical field distur-

bances in the ionosphere during the jet injection Pig.5 presents

the data of tbe electrical field variations recorded by the elect-

rical field detector during separation the plasma accelerator in

the AL-2 experiment.

136 R.Z. Sagdeev at al.

11E AL-2

ioo7 a ,/ari ~a s/art c/ sep4sra~(’on

N-v~KI /OCmV.iii’

50’.. :~lIt i”~’ Vj~~Mck~rnd --

0% __________________________________135 /43 I’iS /47 /49 7~

0 /4.0 2/0 £,in

Fig.5. Changes of DC electric field of the plasma

jet during the accelerator separation.

UE_OUtput of a telemetry channel (~).

L — distance between the rocket and the

accelerator during the separation (m)

It is seen from the data given above that the electrical field

disturbances are observed at distances up to 25 in from the rocket

and the polarized electrical field amplitude reaches 200 to

300 mV m~and significantly exceeds the electrical field strenghts

in the ionosphere of 1 to 10 mV

To characterize the variations of the fluxes of energetic elect-

rons with E>40 key under the experimental conditlons,Pig.6 shows

the data on count rates recorded by Geiger counters.

In the AL-i experiment where the accelerator was not separated from

the rocket the count rate during the injections was 20—30 timeshigher than the backgroundlevel and 2—5 times higher in pausesbetween the injections. The significant anomalies in the count

rate were not observedon the descendingpart of the trajectory

upon stopping the injection. In the AL—2 experiment when the ac-

celerator was separated from the rocket no noticeable integral in-crease of the count rate was observed.

The photometer included in the rocket payload (AL—2) measuredthe

emission of atomic oxygen (&“630 run) excited in the process of

Plasma Jet Injection into Ionosphere 137

~ M,p-s’ ,qL-I10

/02

/0’\~ck9ro~rncJ

we /

10’ ~

0 4 8 4f,S

Pig.6. Variations of the count rate of the Gei-

ger counter recorded in the experiments. AL—i

(the upper panel) and AL—2 (the bottom one);

N — count rate (pulse.S’).

‘the plasma injection. Upon separating the injector, the increase

of the intensity of the emission was observed. It was modulated

by the rocket spinning and correlated with injection pulses. There

was also observed a sharp increase of the emission intensity in

each 4—th or 5—th pulse of the injection, on an average, i.e. with

a periodicity of 12 to 16 a. In the AL—i experiment the neutral

lithium emission was also measured.The data obtained are discussedin [~]

DISCUSSION

The initial stage of the jet motion when riplasma> ~ is charac-

terized by free broadening of the jet [3,4J in the injection zone,

and by forcing out the magnetic field since the condition

~rz~I’1zV. S~/B2> 1 is realized. The values of rL*and L* appropriate

tofi =1 are n=i08 cin3 and L*=i to 10 in with.~tH~H.The

magnetometer measurementsshow that the diamagnetic cavity is not

larger than 1 in under the experimental, conditions. It proves that

the magnetic field diffusion into the jet is rather fast

due to which the injected jet is magnetized. The magnetometer data

138 R.Z. Sagdeev at al.

show that the jet injection results in the appearance of cur-

rents in the rocket vicinity (Fig.4).

The plasma jet motion across the magnetic field must generate the

polarization electric field with strength E=V0xH/C=300 mV m~.

As follows from the direct measurements of the electrical field

(Fig.5) such values of E were measured in the experiment, and in

this case the zone of the polarized flow is 20 to 30 m from the

injector.. The plasma density is 106 to ~ cm3 at the periphery

of the polarized region of the jet.

The radar data show that the effective deceleration of the di-

rectional motion of the jet occurs when the jet motion

is perpendicular to fi and the plasma density is 106 to 1O7 cm3 the-~ -1jet velocity across H does not exceed 200 to 300 ma whereasit

is 10 km s~ at the exit of the accelerator. Such a stopping of the

transverse directional motion of the jet is probably associated with

the ~‘short—circui’t” of the polarization field of the jet by the

field-aligned currents in the background ionosphere [4]

It is worthwhile to stress the appearanceof the anomalousplasma

structures — “focuses” — in the jet (Fig.2).

The possibility of forming such regions during the transverse in-

jection of the plasma at the jet periphery has been shown bySagdeevand A.I.’LIorozov [63 . At relatively low densities of

plasma,ions injected across the magnetic field must be concentratedafter one Larnor turn, in the mode region, “focuses”, at distances

from the accelerator. The ion concentrations in

these “focuses” must be high as comparedwith the background. The

possibility of the “focuses” appearancewas investigated where the

injection was carried out from the separated body within 66to114°—pitchangles. Becauseof the main body together with the in—

strumen’tation complex being in the lower hemisphere,the possibleformation of focuses is considered only during the injection down-

wards with pitch—angles of 66°.

If the injection angle is 66° and the ion energy is 10 eV the high-

density regions (“focuses”) must be formed at approximately 60 m

Plasma Jet Injection into Ionosphere 139

from the plasma source along the magnetic field. In this case the

typical dimension of focuses along the magnetic field will be

30 to 50 m and 40 to 50 m across the field. The crossing of plasma“focuses” by the rocket will occur once per 12 to 16 s. The de-

tection of the photometer and probe signal enhancements with this

periodicity and at distances predicted by the nodel shows the proposed

interpretation possible.

The results of magnetometer measurements of the AL—i experiment

can also confirm the possibility of for:~iing LarL:or curren~ “cir-

cles” of ions appearing during the cyclotron motion of ions. The

amplitude variation and the phase drift of Z—component (Fig.4) re-

corded by the magnetometer traces inside this “circle” testify

the appearance of the additional field generated by the ion current.

The accelerator motion relative to the rocket made it possible to

determine dimensions of the jet along the magnetic field up to its

total thermalization and “submergence” into the ionospheric plasma.

The results of the probe and mass—spectrometer measurements show

that the longitudinal size of the plasma jet is not shorter that

600 m since under the experimental conditions the density of ions

I~i+ at this distance exceeded that of ionospheric ions not less

than by one order of magnitude.

So, at the plasma jet injection across the magnetic field the ar-

tificial plasma formation occurs in the, ionosphere with L~up to

70 to 100 m and L11 up to 1,000 in and density n~i06 cm3. This

formation has a large—scale inhomogeneousstructure and is due to both

the motion and spinning of the rocket which results in a

“plasma helix”, the peculiarities of cyclotron motion of ions

during the transverse injection leads to the generation of plasmaclusters. According to the radar data, small—scale inhomogeneities

with L~1Om develop as the injection stop, these night be simulated

by plasma instabilities of different types [43

The effects due to the count rate increase observedin the AELITA—1 experiment can at present not be interpreted unambiguously and

need further studies. The preliminary data of laboratory experi-

ments where a possible direct effect of the plasma jet on the Gel—

140 R.Z. Sagdeev at a’l.

ger counter records was investigated showed that under the labo-ratory conditions such an effect was not observed. In this con-

nection it can be assumed that the mentioned effects of the count

rate increase in the AL—i experiment can not be caused by the in-

fluence of the jet on the counter. These effects might be explained

by the appearance of fluxes of electrons accelerated in col-

lective processes in the ionosphere during the plasma jet

injection, i.e. when the typical dimensions of APP are much larger

than those obtained under the laboratory conditions.

~he authors are very grateful to the colleagues of the Space Re-

search Institute, the Institute of Applied Geophysics and the KievState University and also to Dr. A.A.Schidlovsky and his co—wor-

kers, who contributed much to the successful experiments.

References

1. A.I.Torozov, Physical Fundamentals of Space ER Thrusters,

Part 1, Atomizdat, Ifoscow, 1978 (in Russian).

2. R.I.’ioisya, Vestnik of KSU, 21, 80 (i979).

3. I.A.Zhulin, V.I.Karpman and R.Z.Sagdeev, Critical Problems of

~fagnetospheric Physics, NAS, Washington, 245, 1972.4. A.A.Galeev, V.S.Dokukin, I.A.Zhulin, V.A.Kapitanov, K.N.Ko—

zubsky, A.I.Morozov, E.V.1~.lshin,I.I.Ruzhin, R.Z.Sagdeev,G.Haerendel, A.P.Shubin and R.K.Snarsky, Investigations on

Solar—Terrestrial Physics, 152, 1977 (in Russian).

5. T.G.Adeischvili, G.G.L~anagadze, and A.A.I4artinson, Bulletin of

the Academy of Sciences of the Georgian SSR, ~, 2 (i979).

6. R.Z.Sagdeev, and A.I.Eorozov, Report presented at USSR—USA

Joint fleeting on Soyuz—Apollo Pro.ject,Idoscow, August 1973.