The passage of debris from a high altitude ( 400 km) nuclear burst over the ionospheric plasma is found to be capable of exciting large amplitude whistler waves which can act to structure a collisionless shock. This instability will occur in the loss cone exits of the nuclear debris bubble, and the accelerated ambient ions will freestream along the magnetic field lines into the magnetosphere. Using Starfish-like parameters and accounting for plasma diffusion and thermalization of the propagating plasma mass, it is found that synchronous orbit plasma fluxes of high temperature electrons (near 10 keV) will be significantly greater than those encountered during magnetospheric substorms. These fluxes will last for sufficiently long periods of time so as to charge immersed bodies to high potentials and arc discharges to take place

Cipolla, J. A.

Golden, K. I.

Pavel, A. L.

Silevitch, M. B.

English

NASA Technical Reports Server

i, .4 ,
i ?- '
!%' Co.tents
i J I. Intr_ducttofl IC,8
! _ 2. Instability Excltat|ot_ Ig9
_" 3. Comparison of BUrst Fluxes With l_lagneto-
i-_t , spheric Substorm Fluxes 17 1
L;' 4. Conclusions i73
i i_ References 173
.}
ii
= i
_-
9. Nuclear Burst Plasma Injection into the!i,
! _';:_ Magnetosphere and Resulting
_ Spacecraft Charging
;_ A.L. Pavel
_ Air F6rce Geophysics labOratory
_: Bedford,Mass.
c_
_,: J.A. Cipolla,M. I_. Sil_vitch,0ndK. 1. G_ldJn
_. N_rth_!stem Uni v_rsiiy
1.5,_
• i} '
:)! :
_, Abstract
The passage of debris from a high altitude (>400 km) nuclear burst over the
i___" ionospheric pl_.sma is found to be capable of exciting large amplitude whistler
_ ,_. waves which can act to structure a collisionless shock. This instability will occur
!=__ inthe losscone exitsofthe nucleardebrisbubble,and theaccelel-atedambient
,_:! ions will free-stream along the magnetic field lines into the magnetosphere. Us-
_-0%;:' tngStarfish-likeparameters and accountingforplasma diffusionand thermalization
of the propagating plasma mass, it is found that synchronous orbit plasma fluxes of
...... high temperature electrons (neai- 10 keV) will be significantly greater than those
encountered during magnetospheric substorms. These fluxes will last for s_ffi-
,: clentlylongperiodsoE tim_ so as to chat'heimmersed bodiestohighpotentialsand
_ arc discharges to take place. Synchi'onous o_-bit satellites expecting to operate in
_ a high latitude, hi:_h altitude nuclear burst environment should be d_signed against
_!. this effect as well as the radiation encountered.
°i
1_7
o
?,
. , ........... , ,.
O0000002-TsF04 "
https://ntrs.nasa.gov/search.jsp?R=19780002197 2020-03-20T12:39:45+00:00Z
I. IVI'i|oIII:'I'III%
TurbuLent coupling between the ejected debris plasma and background air
plasma of a high-altitude nuclear burst appears capable of brin_irtg about electl-on
streaming to high altittides. Itt the presence of the compressed magnetic field
which can penetrate the debris bubble, plasma turbulence takes the form _f large
amplitude whistler waves. Tht_se waves can couple the background air plasma
w.tth the expanding debris plasma, tTot electrons are acquired and some have
sufficiently l_rg_ velocities to escape along the distended field lines. The zlonlin-
ear wave-resonant particle interactions produce anomalous resistivity who_e _cale
length detern_ines the extent of magnetic field penetration into the bubble which, in
turn, determines the rate of escape of _ and plasma electrons.
b_uperalfvdnic debris plasma can escap_ directly through loss cone exits in the
debris bubble since, iti general, the cylindrical axis of the bomb casing is not
initially aligned With.the direction of the geomagnetic field. The more perpendic-
ular the cylindrical axis is to the field lines, the greater the number of _ueh
escape particles. Their superalfvdnic velocities suggest the formation of parallel
collisionless shock waves {Vshock] I_ _ geomagnetic field}. Studies 1, '2 reveal
that such shock fronts are structured by turbulent whistler modes which couple the
incoming background air plasma to tbp __hocked debris plasma. Air plasma can
therefore be picked up by the loss cone debr[c and accelerated to high altitudes.
The presence of a magnetic field has a significant effect on shock wave _truc-
ture. Gradients in the magnetic field give rise te electrOn currents that can drive
ion acoustic waves unstable and increase the effective collision frequency (3' 4)
(this dictates the penetration depth of the compredscd magnetic field into the debris
bubble, so that the rate of escape of debris and air electrons is profoundly affected}.
When propagation is perpendicular to the magnetic field, the magnetic field can
inhibit the electrons from shorting out ion plasma oscillations for wavelengtl_s long
compared with the electron gyroradius 5' 6, 7, 8, 9, 10 and wavelengths short com-
pared with the electron gyroradius. 11, 12 Interactions between the ion beam mode
and the electron Bernstein modes generate instabilities which are stabilized by
electron heating, resonance broadening, or ion trapping. For oblique or parallel
propagation, interactions of whistler waves with ion acoustic beam modes 13 or
ion-cyclotron beam modes 1, 2 are likely to be important, and the existence of
Whistlers depends upon the presence of a magnetic field.
An instability found to be especially attractive as a eollisionless mechanism
for pickup and heating of air electrons is the ion cyclotron beam mode-_hi_tler
mode (current-free) instability that Golden 1' 2 found to be operative along the field
lines and particle trajectories issuing directly from the loss cone exits.
lf;8
.......... - ' /\ . _, _,o ':,, °_°°0 _ "0., o' ........:'_:-__" 8700013£)1313_-T.q _'N_
i ! I ! t I I I
The colllsionlesshock waves can be modeled as Mott-Smith layersof inter-
penetratingunshocked (backgroundair)and shocked (thermallzeddebrls-alrpiston)
flows,so thatthese layersare naturalenvironments for streaming instabilities.
Recent lineardispersioninvestigationsof parallelshock layers2 which form
ahead ofthe debrisplasma issuingfrom tht:losscone exitsrevealthat,fora given
Mach number M A > M* _2.77 (MA - Vu/CA, Vu --shock velocity,CA =Alfv_n
: speed in unshocked plasrnv), the shocked hot ion cyclotron beam mode can always
drive unstable a particular whistler mode which, in the rest frame of the shock
front,isstationarynear theleadingedge. An analysisof the shock interior ,_.
revealsthatthe shock Mach 6urnbeedetermines theportionof the shock thickness
in which unstablewhistlersare stationaryhLthe shock restframe. For M A _ 2.77,
such modes may stand onlyatthe leadingedge, whereas for strongershocks
(M A > 2._7),theymay standat allpointsbetween the leadingedge and some interior
pointwhich isdepefldenton shock strength. For very strongshocks (MA >> I),
fullyone-thirdof the shock thicknessisfilledwiththese modes, which can there-
fore grow to largeamplitudeand couplethequiescentbackground air plasma to the
expandifigdebris-viepiston.
"2. I_1"t!111.11"! EXI:il"t'rIIIX
The number of such debrisparticleswhich entera losscone exitdepends
criticallyon the mass and orientationof thebomb casingjustprior tothe burst.
In the losscone corridor,thedebrisplasma drivesa shock wave. This shock is
structuredby unstablewhistlerwaves which stand at itsleadingedge. To verify
thatthese whistlermodes can grow tosufficientlylarge amplitudeto scatterincom-
ing air ions(as viewed inthe referenceframe of theshock front)the following
" analysis is performed: During daylight burst conditions the density of oxygen ions
z_ isno + -,,105-106, thelargervalue reflectingmaximum sunspot activity.For an
ambient fieldstrengihB ---0,3 gauss, thiscorresponds toan Alfvenspeed
CA _- 163 - 516 kin/see trt the ambient air plasma.
For typical initial casing velocities of from 500 km[sec to 2000 kin/see, the
initial Alfven Mach numbers are from 1.96 to 12.22. A summary of the spectrum
of stationary unstable leading edge whistlers, based on the whistler dispersion
relation, 14 is given in Figure 1. It Is seen there that a broad range of wave num-
bers can grow to large amplitude during daytime (n _- 10it cm "3) bursts. TO
investigate whether these modes can achieve these large amplitudes in the loss
cone exit,we must calculatethe _rowth rateofthese unstablewaves. For slmplic-
Itywe choose ]klCA/_cl 2 _orwhich M A _ 4.12, indicatinga realisticinitial
debrisve_,-cityofu 674 kin/see. Inthiscase the calculatedlineargrowth rate
- o... ,::.o ...... ;:o....." " .... " O0000002-TSF06
I 1 ' I ! ' I
!
i
14
for leadin/_ edge modes, from the whistler dispersion relation, is -_ lfi7yl
where ri is shock strength expressed as the ratio of shocked to unshocked d_nsi-
ties. Fori - 500km and_ =.2 at the shock leading edge, we find'_ _/u _ 10,
indicating 10 e-folding times pass as the shock traverses 5o0 km of the loss
cone corridor. This I kj a 2Stci/C A unstable whistler mode can grow to suf-
ficiently large amplitude after traveling 500 km aloag the loss cone corridor to
pick up background air plasma. "rhe air electrons are rapidly accelerated by
ensuing iOn-electron electrostatic instabilities. Since the calculation is bused
on the lower bound of MA0 it is clear that 10 e-folding times in 500 km is a con-
servative estimate since stronger shocks will have larger growth rates.
3. (:()_11'_{IS():_ OF Iii II_T I,'l,I \1']_ _l'l'll XlXi_M,:'I'iI_I'ilI.]IIII:_l I_S'I'tIIIXiI,'l.l.\t:, _
In the pas*. few years there has been considerable concern over the phenomena
of synchrozkous orbit satellites charging to high potetktials as a resul_ of magneto-
spheric substorms. 15 These substorms consist of the injection of high energy
plasma from the eartll's magnetotail into the reg,.on of synchronous orbit. Those
portions of a satellite subject to the high energy plasma will charge to a potential
several times the electron energy, while other portions of the satellite will remain
at ground potential. Potentials near ground are maintained by photoelectron emis-
sion from illuminated surfaces on the spacecraft or by contact with the ambient
low energy plasma.
During eclipse photoelectron emission disappears, and during a substorm the
ambient low energ), plasma flux is strongly dominated by the injected high energy
plasma. The most damaging discharges probably occur between shadowed space-
craft components influenced by substorm plasma and illuminated components at
ground potential. When the discharge passes througll electrical circuitry between
the components, damage can result. Electromagnetic interference can also result
from surface discharges and considerable surface deterioration can be caused by
arcing.
The following discussion will be an assessment of the possible spacecraft
charging effects which can result from the large scale transport of ionospheric
plasma to synchronous orbit by a nuclear burst. The plasma instability just dis-
cussed demonstrates a mechanism for structuring a eollisionless shock wave.
This mechanism will Operate during a high altitude nuclear burst as the expanding
nuclear debris passes over the stationary ionospheric plasma. Through the inter-
actiotl of large amplitude whistler mode waves, plasma will be picked up by the
collisionless shock and accelerated into the magnetosphere.
171
O0000002-TSF08
, I I I I I I , l
6
'j
=_!
-_, [_!sing nuclvar burst parameters for a Starfish-like (nominally I. 5 megaton)
t burst, 16 calculationsl4 have conservatively estimated that near 1027 0_ ions
, would be carried by the shock when 1 percent of the total debris exits the loss
cone. Depending on orientation, mass, and shape of the bomb casing, this number
i could be considerably higher. This number is reasonably estimated by the mass
: of debris Which exits the loss cone, for ion pickup slows the debris piston and
_, eventually shuts off the pickup instability.
;il The total propagation time for the plasma mass from the burst point just
i. above the earth's surface to synchronou_ orbit is tens of seconds and more than
: sufficient to have thermalization of the complete plasma mass at near the ion
; 17
temperature as the mass slows and diffu,_es.
" The estimated pickup of I02"_04 ions by the nuclear burst shock wave would
have an energy of approximately I0 keV at reasonable shock velocities. The
demands of plasma neutrality would quickly accelerate an equal number of electrons17
_:- which would thermalize with energies equal to or greater than the ion energy.
_/ At the ).oss cone exits these i027 electrons with energies of 10 keV would be in a
(" cylindrical volume of approximately 2 y 1021 cm 3, assuming I percent of the
": nuclear burst bubble as comprising the loss cone exit and the plasma pickup region
being several hundred kilometers in extent. These numbers and energies translate
=, = 3 v I0i5 electrons/cm2-sec.to an omnidirectional flux at the loss cones of Jo
;:' The calculation of fluxes at higher altitudesthan the burst altitudefollows
°_i directly from the Liouville Theorem that a differentialintensityalong particle
=_" trajectory is constant (Jo : Jr)" Conservation of magnetic Flux (BodA ° = BfdAf)
-}' and solid angle area (d,AodL_ o = dAfd_f) yields the following relation between initial
_: omnidirectional flux (Jo) and final omnidirectional flux (Jf); from J =fj d_ and
_. 4_
i.i
( dA° )o, f jfd ,f=f Jo f Jod 'o '• ii 4r 41r o 4_ "
; the relationship, f _ Bo
During a magnetospertc substc,rm, many of the plasma injections observed
--::; are characterized by omnidirectional electron fluXes her 109 electrons/
: cm 2-see. {8, 19 The previous calculations would yield omnidirectional electron
• fluxes from high altitude nuclear bursts of approximately Jf _ 1013 electron._/cm 2-
_ec at synchronous orbit. It i_ clear that these fluxes are significanily greatt_r
than those encountered during a magnetospheric ,_ubsiorm and would poi,sc a strtmp
,spacecraft charging environment.
172
w I /
O0000002-TSF09
While the duration of the nuclear burst and resulting injection will be on the
order of seconds and therefore much _horter than.a typical substorm, ._tudics 20
indicate the charging process takes only fractions of a second.
I. I:ll.M:LI._ IIIX._
The atmospheric nuclear burst environment appears to present the potential
for spacecraft charging effects at synchronous orbits. The calculated rluxe._.
and energies of the injected electrons are greater than those encountered
during substorms0 and wl_ich have been observed to cause spacecraft charging. 4,,
These calculations contain many approximationS, but preliminary results
indicate that it may be expected that synchronous orbit satellites under certain
nuclear burst conditions would find themselves subject to a short, but intense,
period of spacecraft charging. Potentials tn the tens of kilovolts are suggested.
The resulting transient charging arid arc discharging Should be a part of the
destgti criteria of any spacecraft e_pected to _urvive a situation where high
altitude nuclear bursts are involved.
References
1. Golden, K.I., Linson, L.M., and Mani, S.A. (1973) Ion streaming instabilities
with application of collisionless shock wave structure, Phys. Fluid 16:2319.
2. Cipolla, J.W., and Golden, K.I. (1975) Role of streaming plasma instabilities
in parallel shock wave structures, Phys. Lett. 51A:251.
3. Jackson, J.D. (1960) Longitudinal plasma oscillations, Plasma Phys.
(J. Nuclear Energy, Part C) 1:171.
4. Stringer, T.E. (1964) E_.eetrostatic instabilities in c'arrent-carrying and
counterstreaming plasmas, J. Nuclear Energy, Part C 6:267.
5. Papadopoulos, K., Davidson, EI.C., Dawson, J.M., Haber, L, Hammer, D.A.,
Krall, N.A., and 5barmy, El. (1971) tteating of counterstreaming ion beams
in an external magnetic field, Phys. Fluids 14:849.
6. Landau, El. W. (19721 Counterstreaming ion instability for arbitrary angles,
Phys. Fluids 15:1(k91.
7. McBride, J.B., and Ott, E. 11972) Electromagnetic and finite f'e effects on the
modified two stream instability, Phys. Lett. 39A:363,
[ 8. Ott, E., McBride, J.l_., t)r0ns, J.H., and l]oris, J.P. (1972)Turbulent
heatinl_ in computer simulations of the modified plasma two _trearn in,_ta-
bility, Phys. Hey. l,ett. 2_ uS.
173
% i
,o, ,, 0 000000020 0, -TSFIO
.i L 1 I I I I i I
9. McBride, J.B,, ()tt, E., lhJri_. J.P., and ()ren_, J.11. (1972)['hcory :_nd
._imulation -f turbulent heatin_ by tho m,dified t;,,.-L, tr(.a.i in._t:d,tlit?.'.
Phys. ],'luid.-* 15:2367.
10. Cipolla, J.W., and Golden, K.I. (1975) ('r,_field Ix_ap,neh,:_,nic two, _Ire:lm
instability, Can.J. Phys. 5:4:1022.
ll. Lampe, M., Mannheimer, W.M., Mcl_ride, J. lt., Pup:tdopoulos, I'{.,
()rens, J. II., :;hanny, R., and Sudan, H.N. (1973) Theory and _itlnd;,ti_,yL
- of the beam cyclotron instability, l_'hys. I*'luids 15:6f;2.
12. Forslund, D., Morse, R., Nielson, C., anti l.'u. J. (1972) Electrum ryt'h.tron
drift instability and turbulence, Phys. Fluids 15:1303.
13. Lindmatld, E. I,., and Drummond, _,V.I!;. (1071) Studi(.._ _,f t)l)lique ?;hock
Structure, Report ARA-28, Austin Hesearch A-_0ciate_/-|nt::_-_ L
Texas.
14. Cipolla, J.W., Golden, K.I., Pavel, A.L., and Sile_P.,-IL M.IL (l_,Tf;)
-_, Nuclear Burst Induced Shock Wave iModeling of Energetic Electron_Ir_(tion
.into .the _!agneto.sphere r A FG [,-T H -7 _;-0186, A l." (;e,_ph)'s ics [,al)orato ry,
Bedford, Mass.
15. Rosen, A. (1975) Spacecraft Char_ing: Environment indnced anom:dif_s,
_ AIAA Paper 75-91.
16. Zinn, T., Hoerlin, ll., and P. tachek, A. (1.(H;6)Motit_n of btmfl) debris
following the Starfish test, Had|at|on TraE_.d in the Earth's Magnetic
Field, Edited by]lilly McCt)rmac (Gordon and Breach, New York).
:'_ 17. Biskamp, D. (1!,73) Collisionless shock wave_ in plasmas, Nuclear t.'usion,
13:719.
"-_' 18. Sharp, R,D., and Johnson, H.G. (1972) The I)ehavior of h)w-energy parti(*l_s
during substorms, Planet. and Space Sci. 20(N().9):1433.
_.: 19. DeForest, S.F., and Mcllwain, C.F. (1971) I_la_a clouds in the _akmeto-
sphere, J. Geophys. Res. 76(No. 1#;) :3 5117.
_ 20. Rothwell, P.I,., Rubin, A.G., Pavel, A.I,., and Katz, I,. tl_7,)._imulatitm
_'" of the plasma sheath surrounding a ('ha_ed spacecraft, l'roc. (ff(',nlf(,r('nct'
,; on Spacecraft ('harging by Magnctospheric Plas-,;,_, AIAA.
!.
%
--'i, _.


Nuclear burst plasma injection into the magnetosphere and resulting spacecraft charging

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server