and the university of iowa - nasa · geocentric radia3. distance in the geomagnetic equatorial...
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I P " -- ___ -A_--
Department of Fhysics and Astronomy
THE UNIVERSITY OF IOWA Iowa City, Iowa
- A u u
0
https://ntrs.nasa.gov/search.jsp?R=19650014702 2020-03-31T23:55:25+00:00Z
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4 I
. . .
U. of 1- 65-13
Inward Radial Diffusion of Electrons E > 1.6 MeV i n the
Outer Radiation Zen+
Department of Physics arid Astronomy University of Iowa Iowa City, Iowa
* Research supported in part by the Nationa3 Aeronautics and Space Administration under Grant NsG-233-62 and by the Office of &vi? Eesesrch iiiider Contract Nonr-1509(06).
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ABSTRACT pW3
Observations of the temporal variations of electron
(E > 1.6 MeV) intensi t ies near the geomagnetic equator i n the
outer radiation zone with Explorer xw (2 October 1962 to
8 August 1963) strongly suggest that replenishment of energetic
electrons i n the outer radiatioc zone during the ceveral weeks
following a period of geomagnetic act ivi ty prmeeirs by an
inward radial motion of energetic electrons Prom L > 5 .
The apparent, inward radial velocity of the “wave” of
electrons (E > 1.6 Me9 is - 0.4 earth radius (rlay)” at
L = 4.7 and - 0.03 earth radius (day)’l at L = 3.4 and varies
as - L8 between these L-shells. These inward radial velocit ies
for the several repleniskiment cycles of outer zone electrons
(E > 1.6 h V ) observed with Ekplorer XIV a t a given L-shell
are equal t o within experimental errors.
provide evidence f o r a continually active mechanism f o r diffusing
These measurements
energetic electrons across Eshells i n the outer radiation zone.
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I. INTROlXJCaON
The existence of a belt of energetic electrons
(E - 1 MeV) encircling the earth and centered at - 25,000 km
geocentric radia3. distance in the geomagnetic equatorial
plane (i.e., the outer radiation zone) was demonstrated by
in s i t u measurements with some of the earliest earth satellites
and lipace probes [cf. Van Allen, Ludwig, Ray, and I l c l l d n ,
1958; Van Allen md Frank, 1359 a, bl.
energetic electrons i n the interplanetary medium beyond the
earrth's magnetosphere and of energetic electrons precipitated
into the earth's upper atnosphere reveal that the inter-
--
Since measurements of
planetary intensi t ies are insufficient for mintairling the
outer zone intensit ies, a "local" (i.e., within or i n the
immediate vicini ty of the earth' s magnetosphere) acceleration
mechanism driven with the energy of t he solar wind is
generally invoked. i n order t o account fo r the ljnergetic
electrons of t h e outer radiation zone.
zone electron intensi t ies has been stuclied by means of a variety
of Geiger-Mueller tubes and scintilla+,ors on severa l earth
satellites [cf. Forbush e t EL, 1962; McIlwain, 1963; Frank
et al., 1964; Freeman, 1%4].
of these electron intensit ies during end folloWir,g a period of
The morphology of outer
Briefly, the tempord variations
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r
r
geomagnetic act ivi ty are characterized by (a) 811 immediate
enhancement of - 40 keV electron intensi t ies beyond L 2 3.5
and (b) a severe decrease of - 1 MeV electron intensi t ies a t
the onset of the geomagnetic activity, (c) subsequent decay of
electron E - 40 keV intenaities a f te r the i n i t i a l increase of
intensit ies, (d) m increase of electron E - 1 MeV intensi t ies
within a few days a f t e r the onset of the geomagnetic act ivi ty
a t L - - 5 and an increasing time delay ( - three weeks a t
L - 3.5) for the enhancement of intensi t ies with decreasing
L-value, and (e) a,n orderly decay of electron (E - 1 MeV) in-
tens i t ies after the enhancement of intensi t ies at a given
Eshel l .
l e ] revealed that the temporal variations of the radial
profi le of electron (E > 1.6 MeV) intensi t ies near the geo-
magnetic equator ia l plane were characterized by an inward
radial motion of the inner boundary of the intensity peak
persisting for periods of a t l e a s t several weeks and an
apparent radial. velocity - 0.02 earth radius (day)” follow-
ing a magnetic storm.
indicates tha t in-ward diffusion of energetic electrons across
E s h e l l s from L > 5 i s a soxrcc of energetic outer zone
electrons.
Detailed inspection of Explorer XIV data [Frank e t d.,
This apparent radial mt ion strongly
The follow5ng investigation extends the above
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preliminary analysis of the apparent radial d i f m i o n of
energetic electrons (E > 1.6 MeV) observed by Explorer XIV.
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The S.U.I. detector array i n Zxplorer XLV (launch,
2 October 1962; apogee altitude, 98,533 km; perigee altitude,
281 km; orbital inclination, 33") included three collimated
Anton type U 3 thin-windowed Geiger-Mueller tubes with differing
par t ic le energy thresholds and an omnidirectional, shielded
Anton type 302 Geiger-Mueller tube. (Rk a detailed descrip-
tion of these detectors, see Frank, Van Allen, and K i l l s
[ 19641 -) Of particular iaterest i n the present investigation
is the response of the familiar 302 G.M. tube (shielding of
265 rcg
t o penetrating energetic electrans (E > 1.6 MeV) i n the
outer radiation zone from L 2 3 to L - - 5 .
the shielded 302 G.M. tube hss been shown to be tha t due to
penetrating electrons (E > 1.6 MeV) over th i s L-sheU range
by demonstrating that the response due t o penetrating 2rotons
E > 23 MeV [McIlwain, 19631 and due t o nonpenetrating electron
bremsstrahlung [Frank, 1962; E'rank e t al., 19641 is negligible
i n comparison t o the penetrating electron response. The omni-
directional geometric factor (EG) of the 30!2 G.M. tube fo r
counting electrons @ > 1.6 M~V)LS 0.1 & 0.05) cm f o r typical
outer radiation zone spectrums; the present study is concerned
magnesium and 400 mg (cm)02 stainless s tee l )
The response of
2
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with the coqarison of the L-shell profiles of the relative
responses of this detector for sequences of consecutive passes
of the satellite through the outer radiation zone.
response of -the 302 G.M. tube is sanipled for 10.24 seconds
even? 76.8 seconds and the corresponding sanple density is
- 1 sample per 300 km geocentric radial distance along the
portions of the Ekplorer X I V trajectory of interest in the
present investigation.
The
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An example of appazent, radial ly inward motion of
energetic electrons (E > 1.6 MsV) as observed by Explorer XIV
has been given by Fraak, Van Allen, and H i l l s c19641 and is
presently reviewed i n Figures 1 and 2. Figure 1 displays the
omnidirectiond intensity profiles of electrons (E > 1.6 MeV)
as a function of L for three similar passes (in magnetic
la t i tude) through the outer radiation zone preceding a period
of geomagnetic act ivi ty beginning on 17 December 1%2. An
orderly decline of intensit ies Over the ent i re L-shell
range displayed here is evident and the absence of the "slot"
or minimum of intensi t ies at L - 3 is due t o a r t i f i c i a l l y
injected electrons framthe Soviet high-altitude nuclear
explosions i n late October and early Noveniber 1962.
these L-shell intensi typrofi les after the period of geomagnetic
activity, Figure 2 clearly shows the systematic movement of the
inner edge of' the intensity prof i le from L 2 3.8 t o L - - 3.3
and a slow decay of peak intensit ies over a period of - 20 aaJrs, and a return of the intensit ies observed a t L > 4.7 t o pre-
storm vctlues by 8 January 1903.
observation of t h i s slow radia3 movement of energetic electrons
that the period of geamag;netic act ivi ty be followed by a period
Continuing
It is essential t o the abwe
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1 .
of several weeks characterized by re lat ive magnetic quiescace
insofar a~ compolmded cycles cannot be easi ly separated i n an
observational sense. For example, the rCp daily sums c Kp for tne period discussed above were > 30 fo r 17-20 December
and - < 15 over the period 23 December 1962 t o 8 January 1963
with the exceptions of c IQ, = 23 and 18 on 26 and 31 December
respectively (see Frank e t a L E19641).
radial velocity of the inner edge of the outer radiation zone
i n the example e v e n above is - 3 x loo2 earth radius (day)-'
at L - - 3.4.
-
The apparent inward
The long operational l i f e t ine of EqLorer XNprovided
several observations of the chain of events discussed above.
Another example of the replenishment of energetic electron
(E > 1.6 b&V) intensi t ies is shown i n Figure 3 for the period
9-24 March 1963 when the sa t e l l i t e passed through the outer
radiation zone along a trajectory of similar B and L every
three days. The intensity profiles of Figure 3 are displayed
as R function of radial distance f r o m the center of easth and
the variations of magnetic latitude for t h i s series of prof i les
are indicated by a sample geomagnetic I n t i t i e given at
30,OOO km for each profile.
temporal. vari;ttions of the p ro f i l e s displayed i n Figure 3 are
The salient features of the
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the characteristic sparsity of electrons during the storm
period on 9 Ma.rch 1963, the subsequent increase of eiectron
(E > 1.6 &V) intensities in the outer radiation zoae until
- 15 March with a peak intensity at a radid distance of
25,000 km during a period of geo-etic activity) and
sdsequent decay of intensities beyond - 25,OOO km with an apparent motion of the peak of intensities inward to - 20,000 km
by 24 March.
suggests that the electron (E > 1.6 MeV) intensities are
rapidly enhanced during the several &ys follaring the initial
decrease in intensities at the onset of geomagnetic actiety
for L > 5 and proceed t o lower bshells by radial diffusion.
Since the rate of radial diffusion is a strong function of L,
increasing rapidly with increasing L, the initial enhancement
for L > 5 shown in Figure 3 can occur by diffusion of electrons
f’rom the vicinity of the magr:etopause but is beyond the
temporal resolution of the Explorer X I V orbit.
the instrunent is sensitive to only electrons (E > 1.6 MeV)
and, if the first adiabatic invariantp is conserved in this
diffusion process, then the electrons which radially drift
into the outer radiation zone to L - 4 with
This set of chronological intensity profiles
Further, since
E - 1.6 MeV
(detector threshold for penetrating electrons ) have
energies 5 150 keV at L =loand hence are well below the
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302 G.M. tube penetrating-electron energy threshold. The above
two factors l M t the L-shell range over which we can determine
the rates of inward radial diffusion of these electrons.
The third and final example of replenishment of electrons
(E > 1.6 MeV) i n the outer radiation zone is shown i n Figure 4;
the relat ive intensity contours preceding the period of geo-
magnetic act ivi ty beginning 30 April displayed an orderly decline
over the E s h e l l s 3.2 t o 4.6 with a more rapid decay with in-
creasing L. During the storm period a typical rapid decrease
was detected on the 1 April Explorer XIV pass through the outer
zone on all L-shells presented here with somewhat smaller
decreases on the lower L-shells.
intensi t ies of electrons (E > 1.6 MeV) Were enhanced with
increasing time delay and decreasing anrplitude for decreasing
values of L.
intensi t ies at L = 3.2 may be a maiifestation of the inabi l i ty
of the present experimental appratus t o discern a small
increase of intensities on t h i s L-shell above the intensi t ies
of a r t i f i c i a l l y injected electrons frcin the Soviet high-altitude
explosions (see Figure 2) although the absolute intensi t ies at
L = 3.2 and 3.4 do not differ by more than 30% and the
intensi t ies a t L = 3.4 increased by a factor of
time history of the decay of a r t i f i c i a l ly injected electrons
Following the decrease the
The observation of rio sigr,ificant irrcrease of
5. The
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in the "slot" at L - 3 (Figures 1, 2, and 4) indicates that
loss mechanisms i n this region are not more effective than i n
the outer radiation zone [cf. Van Allen, 19641 and indicates
tha t perhaps the presence of the "slot" i s not primarily a
manifestation of a loss mechanism which is more effective along
these Eshel l s but may be attributed t o a weaker source.
temporal intensity profiles of Figures 2 and 4 a l l o w a raugh
determination of the velocities of inward radial diffusion as
a function of L i n the outer radiation zone. These velocit ies
have been estimated by calculating the appsrent inward radial
velocity of the logarithmic half-maxirmrm of t h e inner side of
the "wave" of energetic electrons.
t ion for the two electron (E > 1.6 MeV) replenishment cycles of
December 1%2--Janua,ry 1963 and April-bby 1963 are shown i n
Figure 5.
electrons (E > 1.6 MeV) i s - 0.4 earth radius (day)" and a t
L = 3 . j ~ is - 0.03 earth radius (day)" and the dependence of
t h i s rate of diffusion upon L is - L . velocit ies for the two replenishment cycles are equal a% a
given E s h e l l within the experimentd errors of the present
experiment.
manifestation of the instrument's inabi l i ty t o detect 8 change
i n intensity on this Gshell over the background of art if icially
The
The resul ts of t h i s cdcula-
A t L = 4.7 the apparent rate of inward diffusion of
a The inward radial
The anomalously l o w point a t L = 3.2 ma;y be a
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injected electrcms. A coarse upper limit of - 0.003 earth radius (aay)-l at L = 2.1 has been obtained
measurements [Van Allen, McIldn, and Ludwig, 1959; McnWain,
19613 of artificislly injected electrons produced by the
Argus tests during 1958.
Wlorer N
It is of interest to note that if
the present result is extrapolated to higher Lshells and
a~suming that this apparent inwaxd radid velocity is not a
strong function of electron energy, diff’usion of electrons f r a n
L - 10 (new the magnetopause) to L 2 5 would take place in a
period of - 1 day, a result which is completely satisfactory
with regard to the temporal resolution of the Explorer XIV
orbit for successive outer radiation zone passes (orbita3.
period of sate l l i te : 36.4 hours).
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Iv. DISCUSSION
The present study of the temporal variations of
electron (E > 1.6 MeV) intensities in the outer radiation zone
during several replenishment cgcles followixq periods of geo-
magnetic activity strongly inrplizs that inward raCial diff'usion
of electrons from the vicinity of the magnetospheric boundary
is the primary source of the energetic electrcns in the outer
radiation zone L - 3.0. of electrois (E > 1.6 MeV) is - 0.4 earth radius (day),' at
L = 4.7 and * 0.03 earth redius (day)" at L = 3.4 and varies
&6 - L8 between these L-shells. mgnetic activity (roughly, C KJ? & 30) is followed within
approximately 1 or 2 days by the appearmce of large increases in
the intensities of electrons (E > 1.6 I k V ) in the outer radiation
zone beyond L - 5 and the subsequent inward motion of this
wave" of electrons over a period of weeks following the
> !Che inward radial velocity of the "wave"
The onset of period of geo-
n
geomagnetic storm period.
diff'usion of energetic electrons across Lshells is active
durlng periods of relative magnetic quiescence and the r a i d
diffusion velocities (see Figure 5) are equal to within experi-
mental uncertainties for each replenishment cycle of the outer
radiation zone during this period of observations.
The mechanism responsible for this
From
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extrapolation of the present result and assuming that the rate
of diffusion is not a strong f'unction of electron energy, it
is estimated tha t approximately 1 or 2 days &re required for
an electron t o diffuse inward from the vicini ty of the
msgnetospheric boundary to L - 5 i n agreemeut with the observa-
t ions of the temporal variations of electron (E > 1.6 MeV)
intensi t ies reported here. Hence it appebs!: that the increases
of electrons@ > 1.6 Me9 intensit ies i n the ou";er radiation
zone reflect , wi th the appropriate t i m e delay, increases of
energetic electron intensit ies i n the vicini ty of the magneto-
pause during periods of geomagnetic act ivi ty as indicated by
ZKp and hence are positively correlated with the solar wind
velocity [Snyder, Neugebauer, and Rao, 1g431.
adiabatic invariant p is conserved as an electron moves by
radial. diffusion from L - 10 t o L - 4, then a 150 keV electron
a t the mapfnetopause w i l l acquire ,., 1.5 MeV upon arrival a t
L - - 4.
for the increases of electron (E > 1.6 MeV) intensi t ies i n the
outer radiation zone an increase of electron (E - 150 keV)
intensi t ies i n the transition region or just within the
magnetopause must be positively correlated with a,n increased
solar wind velocity.
( - lo6 t o 10 cm (sec)"') of electrons E 2 40 keV inside
If the first
>
Hence from tne above interpretation i n order t o account
The existence of large intensi t ies
8 2
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the magnetopause is well known [cf. Freeman, 1364; Frank,
19651; and recent measurements [Pan e t al., 1964; Frank and
Van Allen, 1964; Anderson and H a r r i s , 19651 have sham tha t
‘spikes’ of intensit ies of electrons i n t h i s energy range are
frequent i n the transit ion region and are positively correlated
with 3-hour Kp values [cf. Frank and Van Allen, 19641.
[I9601 and Herlofson [1960] have suggested tha t diff is ion is
an ixportant source of enezgetic electrons i n the mter radiation
zone; and recent cElculations by Hess e t al. [19641, Mead and
Nakada [19&], and Nakada e t al. [1$41 assuming that charged
par t ic le trans-L d i m i o n proceeds with conservation of the
ffrst two adiabatic iwariants of motion show t h a t the diffusion
times (i.e., the time required for a charged par t ic le t o mve
from L = 6, f o r example, t o a lower L-shell) would vasy as L
i n agreement with the present coarse experimental result.
Menwain [19651 has recently reported an i m d radial lcovement
of a secondary peak of proton (40 < E < U O MeV) intensi t ies
at L - - 2.2 by 0.15
- 2 x loo4 earth radius (day)” which is only a factor of
- 5 less than tha t given by extrapolation of the present
r e s f i t for electrons (E > 1.6 M ~ v ) to L = 2.2.
of resul ts may indicate that the mechanism responsible for
radial diffusion of chargedparticles i s not strongly dependent
Parker
-0
over a period of two years o r
This comparison
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upon particle mass.
present results obtained near solar minimum with obsemtions
during a different portion of the solar cycle by Escplorers V I
and V I I which were also equipped with shielcled 302
F’urther experiments with increased sensit ivity over a larger
energy range, and for longer periods of observation are
necessary i n order t o further investigate diffusion mechanlbrms
8,s sources of energetic electrons i n the outer radiation zone.
It w i l l b e of interest to conrpare the
G.M. tubes.
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I em indebted to Dr. J. A. Van Allen for several stimulat-
ing discussions concerning the present investigation,
research waa supported in part by the National Aeronautics and
Space Administration under grant NsG-233-62 and by the Office
of Naval Research under contract I$om-l503(O6).
This
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.
Anderson, K. A., H. K. H a S r i s , and R. J. Paoli, Energetic electron fluxes i n and beyond the earth 's outer magnetosphere, J. Geophys . Res., - 70, 1039-1050, 1965 .
Fan, C. Y., G. Gloeckler, and J. A . Simpson, hrldence for > 30 keV electrons accelerated i n the shock transit ion region beyond the earth's mgnctospheric boundary,
Phys, Rev. Letters, - 13, 149-153, 1964.
Fbrbush, S. E., G. Pizzella, and D. Venkatesan, The morphology m d tpsroord variations of the Van AUen radht ion belt , October 1959 t o December 1960, J. Geuphys. Res.,
- 67, 365103668, 1962.
L. A., Wficiency of a Geiger-Mueller tube for non- penetrating electrons, J. Franklin Inst i tute , 273, 91-16> 1962.
L. A., A survey of electrons E > 40 keV beyond 5 ear th radii with Ekplorer XN, J. Geophys. Res., 2, 1593-1626, 1955 . L. A., arid J. A. VB? ALhen, Measurements of energetic electrons i n the vicinity of the sunward magnetospheric boundary with Explorer 14, J. Geugh:%. Res., 9, 493-4932, 1954
L. A. , 3. A. Van Allen, and H. K. HiUs, A study of charged particles in the earth's outer radiation zone with Explorer 14, J. Geopkiys. Res., - 69, dL[L-zLyL, LYW.
.---- A- -.. - - T I .
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Freeman, J. W., The morphology of the electron distribution i n the outer radiation zone and near the magnetospheric boundary as observed by Explorer XTI, J. Ckophys. Res.,
9, 1691-1723, 1964.
Herlofson, N., Mff'usion of particles i n the earth's radiation belts, Phys. Rev. Letters, - 5, 414-416, 1960.
Hess, W. N., J. W. Dungey, andM. P. Nakada, On fluxes of outer be l t protons, Trans. Am. Geophysical Union, 3, 85, 1964 (abstract).
McIlwain, C. E., Coordinates for mapping the distribution of
magnetically trapped particles, J. Geuphys. Res., 66, 3681-3692, 191.
IJfcIlwain, C. E., The radiat ion belts, natural and artificial,
Science, - 142, 355-361, 1963.
McIlmin, C. E., Long-term changes i n the distribution of the 40- t o 110-MeV trapped prctons, Trans. Am. Geophysical - - Union, 46, 141, 1965 (abstract).
Nead, G. D., and M. P. N&&, The Parker mchanism and protons i n the otlter radiation bel t , Trans. AT. Geophysical - Union, 45, 85, 1g64 (abstract).
Nakada, M. P., J. W. Dungey, and W. N. Hess, Theoretical studies of protons i n the outer radiation bel t , Goddard Space Flight Center Res. R e p . X-640-64-U0, 1964.
Parker, E. N., Geomagnetic fluctuations ami tine Toriii of th? outer zone of the Van Allen radiation belt , J. Geophys.
Res., 9, 3117-3130, 1960.
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Snyder, C. W., M. Neugebauer, and U. R. €bo., The solar wind
velocity and its correlation with cosmic-ray m i a t i o n s and with solar and geomagnetic activity, J. Geophys.
A, Res - 68, 6361-6370, lg63.
Van Allen, J. A., Lifetimes of geomagnetically trapped electrons of several MeV energy, Nature, 203, 1006-1~, 1964.
Van !=en, J. A., a d L. A. Frank, Radiation around the earth t o a radial distance of 107,400 kilometers, Nature (London), 183, 430-434, 1959a.
Vsn men, 3. A., and L. A. Frank, Radiation measurements t o 658,300 km with Pioneer IV, Nature (bndon), 184, 23.9-224, 1sB.
Van Allen, J. A., G. H. Ludwig, E. C. Ray, and C. E. Mlwain, Observation of high intensity radiation by sa t e l l i t e s 19% aQha and gamma, Jet Prupulsion, - 28, 588-592, 1958
Van Allen, J. A., C. E. Mdlwain, and G. H. Ludwig, Sa te l l i t e observations of electrons a r t i f i c i a l l y injected into the geomgnetic field, J. Geaphys. Res., e, 87'7-891, 1959.
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FIGURE c m o m
Figure 1. Measurements of electron (E > 1.6 MeV) intensi t ies i n the outer radiation zone (Am 5 30") 8s a function of L for several passes of Explorer XIV preceding and
during the onset of geomagnetic ac t iv i ty on 17 December 1962 (after Frank, Van m e n , and H U s , 1%).
Figure 2. A continuation of Mgure 1 W i n g t he geomagnetfca3ly quiescent period a f te r 22 December which fisrlap the
systematic inward motion of the inner side of the peak of electron (E > 1.6 MeV) intensi t ies (mer Frank, V' Allen, and H i l l s , 1964).
Figure 3. A selected set of radial profi les of the omnidirectionaA intensi t ies of electrons (E > 1.6 MeV) for sever& similar Ekplorer XTV passes through the outer radiation zone .
Figure 4. Relative omnidirectional intensity contours of electrons (E L 6 MeV) as a function of time for various E s h e l l s precedi-ng and after the onset of gecmagnetic ac t iv i ty on X April 1963 which display
the i n i t i a l sudden decrease follawed by an orderly replenishment of electron intensities.
Figure 5. Velocity of inward radial motion of the inner edge of the outer radiation zone peak of electron (E > 1.6 MeV) intensit ies as a function of L. straight line h s been drawn through the data points. If these data are f i t t e d wLth a power law kLn
A
1) (see t e x t ) .
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,
11-39-?,01
IO'
I
IO!
Jo
IO'
lo I
~
EQUATORIAL INTENSITIES OF ELECTRONS, €2 1.6 MeV
I - DEC. 7, 1962 2- DEC. 13 3- DEC. I7
2.0 ~
3
2
0 L
FIGURE 1
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.
IO 8
J O
1 0 4
IOS
EQUATORIAL INTENSITIES OF ELECTRONS, E L 1.6 MeV I - DEC. 7, 1962 4- DEC. 20 5- DEC. 23 6- DEC. 29 7- JAN.8 .1963
laf-37-tjQ 1 I
2 .o 3 .O 4.0 I 0
L
FIGURE 2
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I o6
10'
JO
I 0'
10'
IO2
IO5
JO
to4
to3
IO2
RADIAL PROFILES OF THE OMNIDIRECTIONAL INTENSITIES OF ELECTRONS (E-I.6MeV) FOR SEVERAL SIMILAR TRAJECTORIES
DURING GEOMAGNETIC STORM PERIOD
-- \ I I I
1 I
:CM2-SEc)-'I I -21"
I
- 10 20 30 40
' I ' l l / -23*
POST- STORM
-21"
) 20 30 40
- - 2 2 O I
[MARCH] 1 I I I 1 I I
I 20 30 x 103 KM RADIAL DISTANCE FROM THE CENTER OF THE EARTH
FiGiiiii 3
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> I- CT: z LL I- 2
LL
I-
LL CK
-
-
2 a -
TEMPORAL VARIATIONS OF THE INTENSITIES OF ELECTRONS (E > 1.6 MeV) FOR SELECTED L-SHELLS IN THE OUTER RADIATION ZONE
EXPLORER X I E -
e e
-
- -// I //- f L 4 . 2
\ I 7 /
FIGURE 4
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I .o
IO-
10-2
10-3
APPARENT RATE OF INWARD DIFFUSION OF ELECTRONS ( E > 1.6 MeV) IN THE OUTER RADIATION ZONE
/ /
/ /
/
EXPLORER XE
0
0
DEC, I962 - JAN., I963
APRIL- MAY, 1963
f-
2 .o
/ ' /
/
T
3.0 L
FIGURE 5
4x) 5.0