ELECTRON
PRECIPITATION PULSATIONS
By
F.
V,
Coroniti
and
C.
F.
Kennel
Technical Report
on
SA
Grant
NSG
243
and
NGb
05-003-012
Space Sciences Laboratory Series
10,
Issue
37
Space
Sciences
Laboratory
University
of
California
Berkeley, Ca
1
i
fornia
94720
ELECTRON
PRECIPITATION PULSATIONS
F.
V.
Coroniti
Department of Physics and Space Sciences Laboratory
University
of
California, Berkeley, and
Department
of
Physics, University
of
California,
Los
Angeles
and
’
C.
F.
Kennel
Department
of
Physics
University of California, Los Angeles
Technical Report
on
NASA
Grant
WNGL
05-003-012
Space Sciences Laboratory Series
10,
Issue
37
This work
was
supported
in
part by National Aeronautics
and Space Administration Grant
University of California, Berkeley; National Science Foundation
Grant GP-6817, Office
of
Naval Research Grant NONR-4756
(011,
Atomic Energy Commission Contract
AT(11-1)
-34, Project 157, and
National Aeronautics and Space Administration Contract
NGR
05-007-116,
University of California, Los Angeles; and NASA Contract
AVCO-NASW-1400,
AVCO
Everett Rseeaxeh Laboratory, Everett, Massachusetts.
NGL
05-003-012
I
Electron
Pre
cipitntion
Puls
r?tj
oils
F.
V,
Coi-oniti
211r-l
C.
P.
Keanel
University
of
Celifornia,
Los
Angelcs
ABSTRACT
\%en
high
fre'qaency
wave
turbulence
is
present,
10:~
frequency
TiIiCrOpUlS
ations
czn
s
tYong1.y
nadulate
the
high frccpicncy
wave
amplitudes, leading
to
finite
ercpiitude
pulsations in
thc
loss
rate
of
ens-gctic
electrons
fl-oln
the
magnstospherc,
nic~o~iulsntiort
znplitudk
is
srnall
,
An
extrenely
idealizecl model
suggcsfs
thnt
the
precipit
at
ion
moclulat
ion
depends
exponent
ia
1
ly
on
thc
micropulsation amplitude, tilien
the
nicropulsation period
is
less
than
thc
electron
precipitation
lifetiinc.
*
2-
I.
Introduction
-
.-_._-
--
It
hss
hecn
popu1;2r to rclatc thc
loss
of
cha~ged
pnrtielcs frori
tilc
n;aenctcsyhcre
to
tlic
etnosp?icr~
to
pitch aiig1.e diffusion
drivcn
by micioseopj
c
plasm
turbulence.
(Brice,
1963;
Andronov
and
Tr&htdngc:lrts,
1964;
GCI~I
arid Pe:schek,
1966;
Cor~wz:ll,
1966;
Roberts,
19GS,
1969;
Kcnilel,
1969.)
Those
theoi-i
es
have
gcnc
ral3.y
dcs crj
b
t?d
teii~pora
1
ly
qms
i
-
s
t‘
e
P
dy
p1.c
ci
1)
i
1:
::
t
i
oil
iIot’r.evc3+, observed electron precipitation, which
is
we1
1
docuaicntcd,
is
rarely
even
cliinsi-steady,
exhibiting
a
variety
of
tenporsl
feaiuycs
on
riiillisccoiid to
perhaps
thousand
secoad
tj.inil
scales
(Anderson,
196s)
,
Less
is
know
about
the
teiiipral
stnxturc
of
proton prccipitation.
we
atteript
a
plzusible explanation
for
sone
of
the
elec’iron
pwcipit;i”sion
modulations which
is
within
the
frantework
of
pitch ongle
cliffusion
tlicorjes.
In
so
doing,
we
propose
a
new, but
simple-nindcd,
nonlimar int.eracti.o;i
between
tiavc
moclcs
vhich
is
strongcr
tlwn
those con\rcntionally
di
s.cusscd
in
the
plasia
turbulence
literelure.
In
this
pqxr
-.
s.
’,
The
shortest
millisecond
to
second tinie scale fluctuatioiis in
the
electron precipitation rate
may
we11
be due
to
ionospheric effects
ncar
tl:e
detector
[Lanpton,
1967;
Perkins,
1965)
a
The
similarity
betwcn
the
spatiial
m~rphology and structure
of
x-ray microbursts and
whistler
node
chorus
emissions,
pointed
out
by Russcll,
et
al.
(1969),
suggests
that
1
second
structure(
precipitation
is
related
to
the structurc
in
the
basic turbulent spectrun
resyoiisible
for
precipitation.
of
periods 1or.ger than
a
fer$
seconds need
not
be
localized
may
the
earth,
arid
nay
not
depend strongly
on
thc structure
of
the turbulcnt spectrun,
since
electrons
bounce
many
times
through
the
equatorial planc in
;?
piils2tio.i
pcriod,
durinr!
which
tim
thc
cliorus
structure
has
chanrcd. Hov3fully,
lorirr
llie
mechanism driving prccipitation
pulsntions