Author(s)
Weddle, Leonard Earl.; Olsen, Richard C.
Title
Ion gun generated electromagnetic interference on the SCATHA satellite.
Publisher
Issue Date
1987
URL
http://hdl.handle.net/10945/22328
This document was downloaded on May 04, 2015 at 23:26:06
L
NAV
"
NAVAL POSTGRADUATE SCHOOL
Monterey
,
California
THESIS
ION GUN GENERATED ELECTROMAGNETIC INTERFERENCE
ON THE SCATHA SATELLITE
by
Leonard Earl Weddle
December I98?
Thesis Advisor:
R. C.
Olsen
Approved for public release; distribution is unlimited.
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ION GUN GENERATED ELECTROMAGNETIC INTERFERENCE ON THE SCATHA SATELLITE.
12
PERSONAL AJTHOR(S)
Weddle
,
Leonard E.
TYPE OF RE D OR T
13a
3b
Master's Thesis
=
r
'ME
COVERED
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DATE OF REPORT
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(Year,
Month, Day)
15
PAGE COUNT
71
198? December
T
ROM
SUPPLEMENTARY NOTATION
16
COSATi CODES
F
E.D
GROUP
ABSTRACT (Continue on
19
18
reverse
if
SUBJECT TERMS (Continue on reverse
if
necessary and identify by block number)
Ion gun, Ion beam, Plasma waves, SCATHA, Spacecraft charge
control, Satellite charging, Artificial particle beams
SUB-GROUP
necessary
and
number)
identify by block
Spacecraft charging at geosynchronous orbit can cause satellite anomalies and failure.
Experiments in charge control were conducted on the joint Air Force/NASA P?8-2 (SCATHA)
satellite using both electron and positive ion emission systems. These experiments were
monitored by a variety of plasma wave and particle detectors. Plasma wave data show that
arcing was taking place during n on -neutralized ion beam emission. The arcing was seen to
cease when either the beam was neutralized or the beam acceleration voltage was turned off.
Evidence exists which indicate that the arcing is due to differential charging on the
satellite surface. A possible effect of non -neutral, non-accelerated ion beam emission is
The effect
the shielding of the electric field antenna from ion gun generated plasma waves.
of shielding these signals is an increase in the sensitivity of the electric field receiver
to natural signals.
DiSTR'BUTiON- AVAILABILITY OF ABSTRACT
20
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Approved for public release; distribution is unlimited
Ion Gun Generated Electromagnetic Interference
on the SCATHA Satellite
by
Leonard Earl Weddle
Lieutenant, United States Navy
B.S., Purdue University, 1979
Submitted in partial fulfillment of the
requirements for the degree of
MASTER OF SCIENCE IN PHYSICS
from the
NAVAL POSTGRADUATE SCHOOL
December 1987
ABSTRACT
Spacecraft
anomalies
satellite
at
geosynchronous orbit can cause
Experiments
failure.
and
conducted
were
control
charging
on
the joint Air Force/NASA P78-2
(SCATHA)
satellite
using
both
emission
systems.
These
experiments
data
show
ized
ion
either
beam emission.
the
were monitored by
a
Plasma wave
beam
was
The arcing was seen to cease when
neutralized or the beam acceleration
Evidence exists which indicate that
arcing is due to differential charging on the satellite
surface.
ion
and positive ion
that arcing was taking place during non-neutral-
voltage was turned off.
the
electron
of plasma wave and particle detectors.
variety
in charge
beam
antenna
A possible effect of non-neutral, non-accelerated
emission
is
the shielding of the electric field
from ion gun generated plasma waves.
The effect of
shielding these signals is an increase in the sensitivity of
the
electric
field
receiver
to
natural
signals.
TABLE OF CONTENTS
PAGE
I.
II.
III.
IV.
V.
INTRODUCTION
7
A.
PROBLEM OF SATELLITE CHARGING
7
B.
HISTORY OF ACTIVE EXPERIMENTS
8
C.
THEORETICAL EXPECTATIONS
9
SCATHA PROGRAM
11
A.
SATELLITE
11
B.
ION GUN
11
C.
DETECTORS
13
OBSERVATIONS
17
A.
19 JULY 1979
B.
2
C.
SUMMARY OF OBSERVATIONS
APRIL 1979
2214:00 - 2314:00 UT
17
1513 - 1538 UT
40
52
CALCULATIONS
54
CONCLUSIONS
58
APPENDIX - EXPERIMENTS AND GUN COMMANDS
60
LIST OF REFERENCES
64
BIBLIOGRAPHY
67
INITIAL DISTRIBUTION LIST
69
-002
LIST OF FIGURES
PAGE
I.
The P78-2 SCATHA satellite
12
2
SC4-2 ion gun block diagram
14
3.
SC4-2 ion gun electrical schematic
15
4.
Spectrogram of the period 2302:34
19 July 1979
5.
Frequency spectrum of magnetic field data at
2302:59 19 July 1979 using 3 second averaging
21
6.
Frequency spectrum of electric field data at
2302:05 19 July 1979 using 3 second averaging
22
7.
Spectrogram of the period 2217:55 - 2218:38
19 July 1979
23
8.
Frequency spectrum of magnetic field data at
2218:00 19 July 1979 using 3 second averaging
25
9.
Frequency spectrum of electric field data at
2218:15 19 July 1979 using 3 second averaging
27
.
-
2303:26
19
10. Spectrogram of the period 2226:36 - 2227:18
19 July 1979
28
II. Spectrogram of the period 2228:30 - 2229:14
19 July 1979
30
12. Frequency spectrum of electric field data at
2228:53 19 July 1979 using 3 second averaging
31
13. Frequency spectrum of magnetic field data at
2229:45 19 July 1979 using 3 second averaging
32
14. Plasma waves generated by beam-plasma interactions - 33
15.
Spectrogram of the period 2233:56 - 2234:37
19 July 1979
35
16.
Spectrogram of the period 2301:09 - 2301:55
19 July 1979
37
PAGE
17. Narrowband filter data for 2130-2330 19 July 1979
—
38
18.
Spectrogram of the period 1512:54
2 April 1979
1513:28
42
19.
Spectrogram of the period 1517:22 - 1518:02
2 April 1979
43
20. Spectrogram of the period 1518:37 - 1519:16
44
2
-
April 1979
21. Spectrogram of the period 1519:44 - 1520:24
2
46
April 1979
22. Spectrogram of the period 1520:58 - 1521:38
2
47
April 1979
23. Spectrogram of the period 1522:00 - 1522:40
2
48
April 1979
24. Spectrogram of the period 1540:14 - 1540:56
2
50
April 1979
25. Narrowband filter data for 1400-1600 2 April 1979
26. Hollow cathode density profile
—
51
55
I
A.
INTRODUCTION
.
PROBLEM OF SATELLITE CHARGING
immersed in a plasma will reach an equilibrium
probe
A
potential
where
the
probe
zero.
A rocket or satellite in the ionosphere or
is
sum
of
the charging currents to the
magnetosphere is just such a probe.
the
space environment are due to incident ambient electrons
and
photoemission,
ions,
Experimental
to
results
potentials
ambient
in
the
to
eclipse.
thermal
In
at
not
a
high
altitudes.
of the
sunlight, positive
problem
charging is
low altitudes because of low
at
Satellites at high
such as those in geosynchronous orbits, however,
altitudes,
into the negative kilovolt range.
charging
experience
Clearly
energy
Satellite
temperatures and high densities.
plasma
emission.
of a few volts are found due to the dominance of
photoemission
generally
secondary
and
show that satellites typically charge
comparable
plasma,
potentials
can
The largest currents in
satellite carrying experiments designed to study
a
the satellite environment will have problems doing so if the
satellite
surrounding
satellite
plasma.
users
differential
many
always changing its potential relative to the
is
though
charging.
different
Of
much
greater concern to most
is electrical discharges caused by
A
satellite's
surface is made of
materials, some of which are conductors and
7
.
These different materials can charge to
dielectrics.
some
When the potential difference
greatly different potentials.
between
surfaces
two
is
of
sufficient magnitude, an
The current thus induced
electrical
discharge
will occur.
cause
anomalous
commands
can
to
be
sent
satellite
to
minor or major damage to satellite components, and
systems,
complete
sometimes
system
satellite
or
failure.
(Refs.
1,2,3,4)
B.
HISTORY OF ACTIVE EXPERIMENTS
charging
satellite
was
satellite
(SCATHA)
P78-2
The
created
to
study
and provided with active charge control
The SCATHA satellite
ion and electron guns.
devices,
e.g.
was
first satellite at geosynchronous orbit capable of
the
observing
VLF
emission
ion
experiments
conducted
by
in
ionosphere
the
rockets
a
positive
have been, however, many
There
system.
aloft
carried
waves during operation of
plasma
also
that
with
ion beams
carried plasma wave
receivers
Porcupine
The
During
detected
and
ARCS
gun
ion
near
at
the
rockets
sounding
rocket
experiments
harmonics
of
carried a Xe
electrostatic
H
and
ion gun.
emissions were
cyclotron frequencies
lower hybrid frequency (Refs. 5,6,7,8).
carried
Ar
ion
guns.
These
The
experiments
observed many low frequency electrostatic emissions with the
most abundant being near the lower hybrid frequency and some
8
near
also
Two
upper
the
frequency (Refs. 9,10).
hybrid
ion generators were flown on a sounding rocket
Ar
launched from Sondre Stromfjord, Greenland to study ion beam
dynamics
and
parallel
to
perpendicular.
During
observed
and
the
that
field
produced
one emitted its beam
the other one
and
cyclotron frequency
frequency.
emissions
The
beam operations emissions
parallel
hybrid
ionosphere.
the
on
near multiples of the H
lower
operations
such
magnetic
the
were
effects
arranged
were
generators
beam
ion
at
Perpendicular beam
cyclotron
and
He
harmonics (Ref. 11).
C.
THEORETICAL EXPECTATIONS
limited
A
done
such
for
hydrogen
observed
experiments
is
the
beam
magnetic
regions.
the
give
experiments.
They
predict the
H
While
the
ionosphere
where H
is a
At geosynchronous orbit the environment
ranging
with
density
field
in
These
5,7,9,10,12,13).
(Refs.
place
took
constituent.
mostly
beam
ion
cyclotron harmonics and the upper and lower hybrid
frequencies
minor
number of theoretical calculations have been
large
strength
compared
is
also
from 10 to 50 percent and
to
ambient.
the
different
in
the
The
two
these differences prevent us from applying
results of these calculations to our situation, they do
us
reasonable
ideas on where to start looking.
to
assume
that
We believe it is
plasma waves at some frequency
would
generated
be
orbital
altitudes,
the SCATHA ion gun.
by
the
H
cyclotron
At the SCATHA
frequency
and
the
lower hybrid frequency are too low to be observed by the SCI
experiment,
although
second
receiver
(SC10)
is
occasionally available for this lower frequency regime.
The
electron
The
a
cyclotron frequency was generally a few kilohertz.
majority
of
the
work
which
higher frequency range.
10
follows deals with this
SCATHA PROGRAM
II.
SATELLITE
A.
P78-2
The
part
of
nearly
5.3
AT
Altitude (SCATHA).
High
perigee,
shaped
satellite
meters
high.
and
7.8
measures
made
is
surfaces.
insulating
solar cell glass covers.
mostly
is
composed
with
stabilized
axis
-
earth
experiments
positions
P78-2
The
of
are covered primarily by
sides
conducting
up of insulating and
The forward end of the
surface while the after end is
insulators.
satellite
The
was spin
period of about 60 seconds with its spin
a
the plane of the orbit and nearly perpendicular to
in
the
a
The cylindrically
1.7 meters in diameter and 1.75
surface
Its
It was placed into a
apogee.
R^
conducting
satellite
1979 as
orbit with a 7.9 degree inclination,
geosynchronous
R^
launched January 30,
was
joint Air Force/NASA program to study Spacecraft
a
Charging
satellite
sun
line.
carried
on
Appendix
The
SCATHA
has a list of the
shows
the
of some of the experiments on the satellite.
The
experiments
used
and
Figure
1
this work are the ion gun and
for
plasma wave experiments. (Refs. 14,15,16)
B.
ION GUN EXPERIMENT
The
positive
ion
gun
charge,
experiment (SC4
to
- 2)
was designed to emit
induce negative voltages, and to test
11
SC 10-3
Electric Field
Experiment
sen-
i
Magnetic Field Sensor
SC10-2
SC2-2 V Cente:
Tube
\
-Z
SC6-1
SG7-3
SClO-y*
SC11-1
+Y
-Y
SC4-2
+z
\
Aft End View
^X^SGl-^
yscio-^
SG2-1
Figure 1.
The P?8-2 SGA'THA satellite.
12
the effectiveness of ion beams in controlling charging.
experiment
electron
included
which could be used to neutralize the beam
source
The ion system used
cathode discharge to ionize xenon gas which could then be
a
accelerated
cathode
either
by
a
kV or
1
and exit aperture.
increments
in
diagram
of
from
The
functions.
(Ref. 17)
kV potential between the
gun
and
Appendix
to
2
mA
Figure
lists
2
is a block
is an
electrical
Figure
.
3
gun commands and
ion
DETECTORS
.
wave
receiver.
wave
experiment.
antenna
for
portion of the SCI experiment was a VLF
A
The
measures
100
m
experiment
tip
with
2
area
is
receiver
has
sensitivities
field
1
/2
'
)
at
receiver
m
loop antenna is
The
and mounted on a
shielded
575
The inner 30 m of each half
insulation.
effective
V/(mHz
a
10
x
5
sensitivity of
13
m boom.
Its
The electric field
at 1.3 kHz.
of
2
3
x
10
-7
and 10
-7
The magnetic
1.3 and 10.5 kHz respectively.
has
dipole
The two halves extend
tip.
to
Kapton
electrostatically
SC10
the
The dipole antenna
field measurements.
perpendicular to the spin axis.
coated
used
field measurements and an air - core
electric
magnetic
for
loop
diagnostic used in this work is the plasma
primary
The
is
2
The ion current could be varied
mA
0.3
ion
the
schematic.
C
positive ion emission system and an
a
ions or to provide electrons alone.
of
The
—6
nT/Hz
1 /
2
4
at
c
o
H
C\2
I
o
en
CD
faO
•H
14
ANODE
NOTE
CURRENTS SmOWN
FOR IONS
TELEMETRY
RETURN
Figure 3-
SG^-2 ion gun electrical schematic.
15
1.3 kHz and a 60 dB dynamic range.
filters and a broadband mode.
band
narrow
filters
Outputs consist of eight
bandwidths
have
10.5,
The narrow band
of + 7.5% and frequencies of 0.4,
100 and 300 kHz.
In the broadband
1.3,
2.3,
3.0,
mode
the
receiver can be set to cover either the
or
-
5
kHz
30,
frequency
16
range.
(Refs.
0-3
kHz
14,15)
Ill
Three
for satellite charge control is with both the ion beam
mode
and
First, the primary
modes were studied.
gun
ion
OBSERVATIONS
.
neutralizer
satellite
The
on.
thus
is
emitting
a
neutralized
ion
experiments
were
conducted
neutralizer
off.
Only zenon ions are emitted in this mode.
Finally,
third
trickle
a
mode
acceleration
beam.
the
mode
with
exists
beam
ion
the
ion beam on and the
termed 'trickle mode'.
discharge
is on,
In
but without
We will look at data taken in
grids.
the
by
induced (negative) charging
Next,
each of these three modes.
22:14:00
19 JULY 1979
A.
first
The
ion
-
23:14:00 UT
example of plasma wave observation during an
gun experiment comes from 19 July 1979 (Day 200).
This
example illustrates typical observations for:
-
gun off.
-
gun and high voltage on, neutralizer off.
- gun on,
The
high voltage and neutralizer off (trickle mode).
satellite
between
varies
=7.6
L
from
frequency
is
is near local dusk
location
1.8
and 8.0.
kHz
around
to
1
(1954-2042 LT),
The electron cyclotron frequency
2.2 kHz.
The hydrogen cyclotron
Hz and the lower hybrid frequency is
1?
-
40
about
50
Hz,
and hence these latter two fundamental
frequencies are off scale.
form
wave data we shall show is primarily in the
plasma
The
The vertical axis is frequency and all of our
axis is time.
Hz to 4.0 kHz frequency range. Signal
spectrograms cover a
strength
is
spectrogram
exist
In the spectrograms the horizontal
spectrograms.
of
indicated
will
grey
a
where
frequencies
at
received.
Comparison
frequencies
is
made
Thus,
scale.
the
white at frequencies where no signals
be
dark
and
using
signal
of
signals
are being
strength at different
by comparing the relative darkness of
the spectrogram at those frequencies, with the darker region
higher
representing
signal
strength.
The plasma wave
receiver on the satellite switches antennas every 16 seconds
between the electric field antenna and the magnetic
cycling
field
antenna.
electric
seconds.
data
Typical
and
the spectrograms cycle between the
the magnetic field data every 16
'gun-off
data are shown in spectrogram
in Figure 4 which covers the period of time 2302:34 to
form
2303:26.
plasma
in
field
Hence,
The 19 July 1979 broadband data was taken with the
wave
receiver in the
0-3
kHz mode.
this mode introduces a roll-off at
spectrogram.
noise
3
kHz,
The bandwidth
as seen in the
This spectrogram shows the receiver background
normally present in the magnetic field (B) data.
The
receiver noise is the resonant response of the receiver to a
white
noise
input,
as
determined by ground calibration.
18
I
(
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noise is not visible in the electric field (E) data at
This
Also visible is
level used to make these spectrograms.
the
interference
monochromatic
interference
700 Hz and 2100 Hz and weak
at
These signals are caused by a 700
at 1400 Hz.
tuning-fork driver circuit in another experiment and are
Hz
not
in the electric field data.
seen
show
The next two figures
the features of Figure 4 more clearly.
Figure
5
shows
a frequency spectrum of the magnetic field data with the gun
taken
off
create
2100
and
frequency
the
Hz
background.
is
clearly
are
shows
6
a
The 700 Hz
to be well above
seen
frequency spectrum of the
Two
The latter signal
found at 2570 Hz and 3155 Hz.
are
low
signals
Figure
probably
The
spectrums we shall show.
field data with the gun off taken at 2303:05.
electric
peaks
Three second averages were used to
2302:59.
at
electron cyclotron harmonic, or (3/2)f
the
frequency
peak
(about 100 Hz) may be an artifact
the spacecraft.
generated
on
frequency
cut-off of the receiver band-pass. (Refs. 18,19)
data
The
or
near
It is near the low
set presented below (e.g. the broadband data)
began
while the ion gun was on with an accelerating voltage
of
kV
1
and
a
beam
filament power was off.
region,
The neutralizer
The satellite was in the dusk bulge
in a relatively quiet plasma sheet environment.
was uncharged
approximately
(Ref.
current of 2.0 mA.
20).
(<
It
+10 V) when the gun was off, and charged to
-800 V when the gun was on, and unneutralized
The
top
of
panel
20
Figure
7
is a spectrogram
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Ion gun power
Ion gun high voltage
-
Neutralizer power
Ion beam voltage
.0mA
1.0mA
0.3mA
Ion beam current
-
2mA
.2mA
-
0.4mA
-
2
I
n
1
.
0V
NBL -10V
-25V
-100V
-
Neutralizer current
Neutralizer bias level
-I
Figure 7.
Spectrogram of the period 221 7:55
2218:38 19 July 1979.
23
-
about
showing
seconds of plasma wave data for this ion
43
Also shown in Figure
operating mode.
gun
voltage
current
beam
ion
(V, ),
neutralizer
(HV),
neutralizer
and
switched
of
current
(I
),
Again, the receiver was
3
kHz is due
There is a broad maximum from 1.0 to
spectrogram
the
at those frequencies.
present in the electric field data.
not
is
striations
vertical
data,
neutralizer
(^vJ*
beam voltage
visible in the magnetic field data as shown by the
darkening
signal
ion
16 seconds and the roll-off at
every
kHz
1.5
(NP),
bias level (NBL).
the receiver mode.
to
power
are the ion gun
gun power (IGP), high
ion
include
These
settings.
mode
7
This
Brief,
in the data, particularly the magnetic
show a broad spectrum which we interpret as the signal
generated
arcing
by
striations
obviously
are
considerably
The vertical
on or in the satellite.
due
less than a second.
to
pulses with periods
The frequency spectrum is
analyzed in more detail in the following two figures. Figure
8
is
frequency
a
spectrum
of the magnetic field data at
The spiky elements attributed to arcing have largely
2218.
been averaged out by three second averaging.
that
followed
peak
most
the
by
to
Consideration
average
signals are below 500 Hz,
broad peak from 1.1 - 1.4 kHz.
a
is the broad
similar
this
intense
Figure 8 shows
the
of
This latter
maximum visible in the spectrogram and is
receiver
noise
signal shown in Figure
5.
filter data (below) show that
calibrated
signal is orders of magnitude higher in amplitude than
2k
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background
receiver
Figure
response
appears
to
be,
therefore,
the
an intense white noise input signal.
to
frequency spectrum of the electric field data
is a
9
broad
A
2218:15.
at
This
noise.
from near zero to about 1.5
signal,
kHz, monotonically decreasing in amplitude is seen in Figure
but was not present in the gun-off data of Figure 6.
9
smaller
The
peaks
2.5 kHz and 3.1 kHz are still visible.
frequency spectrum is similar to that found in the
low
magnetic
signal
near
data
field
Figure
but, again there is no
8,
region of the electric field
- 1.4 kHz
1.0
the
in
of
data as there is in the magnetic field data.
at
(f
3.1
kHz
is
=
2.1
kHz
ce
data
The
again
at
thought
this
be the (3/2)f
to
time,
The small peak
as
signal
calculated from SC11
)
At
the high voltage is turned off resulting in
2226:55
trickle
A net current of 10
mode.
- 20
microamps is still
being emitted (according to gun diagnostics).
The result of
this
ion emission is a satellite potential near zero (< +10
V).
The
measurement
field
show
as
shown
7
by
ceases during an electric
Figure 10.
Still visible
trickle mode is the broad maximum from 1.0 - 1.5 kHz
during
in
arcing seen in Figure
the
magnetic
field data.
Calibrated filter data still
substantial enhancement over receiver background.
intense
low
The
frequency (near 100 Hz) signal in the electric
field data present with the gun off, and the gun on, remains
visible.
The
signals
become
26
clearer
over
the
next few
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a
.^ri.jUiiliiijsjii2ig._J
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ON
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I
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-
-
-
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1.2mA
n
0.4mA
2
I
0V
NBL -10V
-25V
-100V
-
-
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Figure 10.
Spectrogram of the period 2226:36
2227:18 19 July 1979.
23
-
Figure
minutes.
shows
11
that at 2229 both the broadband
signal in the magnetic field data and the very low frequency
in the electric field data have become more intense,
signal
but have not substantially changed in character.
narrow
field
period.
because
natural
latter
This
data.
this
a
now visible at about 1.2 kHz in the electric
signal
during
There is
We
of
its
signal is not generally visible
interpret
width
finite
signal as being
this
and
variation
in
frequency. Figure 12 is a frequency spectrum of the electric
The intense signal from near zero to
field data at 2228:53.
about
up
Hz remains, with several additional narrow peaks
200
about
to
500
Hz
.
Also
the
line spectrum shows the
feature seen in Figure 11 at 1190 Hz, and an additional peak
exists
weakness
kHz
3.16
at
of
(again
(3/2)f
).
The apparent
3.16 kHz signal is partly due to receiver
the
roll-off in this mode. Figure 13 is a frequency spectrum for
the magnetic field data at 2229:45.
1.5
kHz
is
similar
The broad peak from 1.0
to that found previously; that is,
similar
to the receiver resonance response to a white noise
input.
The
Figure
lower
frequency
8
is
now
nominally
be
associated
plasma,
while
induced
by
and
14(a)
the
(below 500 Hz) seen in
Hence the low frequency peak must
with
the accelerated beam in the
broad peak (white noise) is most likely
interactions between the cold, dense gun plasma
ambient plasma.
shows
gone.
peak
a
To illustrate this graphically, Figure
velocity distribution for an accelerated Xe
29
KeH-
*
B
-5»K-
4-
ON
OFF
IGP
HV
ON
OFF
NP
ON
OFF
V.
2kV
lkV
b
2
x
I
b
n
1
2
1
2229:00
.0mA
.0mA
.
3mA
.
2mA
.2mA
.4mA
0V
NBL -10V
-25V
L00V
Figure 11.
Spectrogram of the period 2228:30
2229:1^ 19 July 1979.
30
-
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,-H
Beam
in
Plasma
Mixed Plasma Clouds
f
f
Cold Xe+
AmJBient
H+
t
Velocitv
(a)
Velocitv
(o)
White Noise
Ion Acoustic
Mode
Frequency
Frequency
(d)
00
53
g
> 1
K
vH
o d.
/T^\
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/
<V
V
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cc
cc
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Frequency
"
(e)
Figure 1^.
Plasma waves generated by
beam-plasma interactions.
33
H+
beam
in
cold
a
instability
plasma.
H
waves
is
in
frequency
distribution
21,22).
Similarly,
distribution
It
for
likely
is
suggest
Figure
Xe
possible
result of this
acoustic
ion
in
Figure
14(c)
shows
shown
as
cold
a
the
A
cloud
mode
with a
14(b)
(Refs.
a
in a cold H
velocity
plasma.
that this distribution is also unstable.
that
result
the
is a
We
spectrum of nearly constant
amplitude over a wide frequency range (white noise) as shown
in
Figure
produce
receiver response as shown in Figure 14(e).
a
magnetic
Again, a white noise signal is known to
14(d).
field
data
have
The
cleaned up substantially and in
particular, the 700 Hz and 2100 Hz lines are not visible. It
is
now clear that this is because more intense signals have
driven
AGC down, and these relatively weak markers are
the
below the noise level.
now
voltage is turned back on.
former
their
resume
intense
artifact
be
driven
Re f
.
2
The AGC may
by a different portion of the frequency spectrum
latter
characteristics
(
character. The signals do appear more
of AGC and processing variations.
this
trickle
The arcing resumes, and the data
the spectrogram (not shown), but this is partly
in
an
during
At 2232:03 (not shown) the high
mode
of
This could reflect different
period.
differential
charging following the
induced discharge of the dielectric materials
3).
There
are
changes in the data which are independent of
gun status change.
Figure 15 shows that at 2234:04 there is
34
* B^
IGP
HV
ON
OFF
ON
OFF
223^:04
-
NP
ON
OFF
-
V.
b
2kV
lkV
-
2
.0mA
1.0mA
D
0.3mA
I.
-
-
I
2.2mA
1.2mA
n
0.4mA
-
-
0V
NBL -10V -25V -100V J
Figure 15.
Spectrogram of the period 2233:56
223^:37 19 July 1979-
35
-
a
changes
in intensities which is independent of any
change
sharp
gun
ion
the
in
of the narrowband filter
Examination
however.
unchanged,
The spectrum is largely-
status.
data (shown below) reveals that this amplitude change occurs
the .4 kHz - 3.0 kHz channels of the electric field data
in
turned
about
one
mA
decrease
frequency
of
two
to
spin
than
decrease
to
Figure
in
intensity, and
16 shows data at 0.3 mA
The spikes that indicate arcing are seen to
intense
less
and
fewer
were
they
in
number per each 16 second
at 2.0 mA beam current.
characteristics of the spectrum remain the same.
all
periods).
caused the arcing signals
current
occurrence.
current.
window
beam
in
striations)
(vertical
be
(one
at 2300:22 the beam current is decreased to 0.3 mA.
and
beam
dB above the
10
At 2258:06 the beam current is decreased to 1.0
data.
Each
3.0 kHz
operating mode changed the plasma
gun
the
in
to
5
-
The transient period lasts
levels.
minutes
two
to
Changes
wave
gun-on
state'
'steady
data in the 0.4
field
approximately
briefly
peak
range
electric
the
on,
When high voltage is
mode operations.
trickle
both
after
ion
gun
power
is
turned
off.
All other
At 2301:39
Figure 16 shows that
arcing ceases and the the 700, 1400 and 2100 Hz interference
lines are again visible.
operation
The
narrowband
filter
shown
both
for
summarized
is
data
for
antennas.
the
Figure 17.
The
period 2130 - 2330 UT is
Trickle
36
in
mode
operations were
IGP
ON
HV
ON
NP
ON
OFF
V,
2kV H
lkV
b
I.
D
-
1.0mA
0.3mA
-
.2mA
-
0.4mA
-
NBL -10V
-25V
-100V
-
I
n
1
-
-
Figure 16.
Spectrogram of the period 2301:09
2301:55 19 July 1979.
37
-
r
r
r
r
SCATHA
AEROSPACE RECEIVERS
1
JULY 1979
9
SCI- 8A
MAGNETIC ANTENNA
ELECTRIC ANTENNA
—————
i
N
X -40.0
? - 50.0
§ - 60.0
ro
I
i
i
i
_
™i
———
—
i
i
i
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————
i
i
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I
I
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-
-
7 0.
40
O
O
5
60
7
I
4
O
to
CD
o
30
60
70
H
I
1
I
I
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II
1
I
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H
:
40
I
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I
i
i
V
I
trickle mode
trickle mode
|
V
v
,
V
tfrfVr^
3
6
70
Id
Q
3
40
o
3
ro
60.
0.
70
<
^h^wm-r^
LN**1
40
rO
30
CVJ
60
-
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70,
:7*t^r
40
ro
3
60
70
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40
30.
60
70
'
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I
I
L
79200
13000
I
|
l
I
l
82800
223000
|
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213000
UNIVERSAL TIME
Figure 17.
Narrowband filter data for
2130 - 2330 19 July 1979.
38
J_
I
79200
82800 (SEC)
30 00
=
from 2159:06 to 2203:35 as well as the 2226:55 to
conducted
2232:03
2.3
1.3,
and
electric
in
mode.
amplitude
magnetic
trickle
The
increase
is
greater
The
amplitude
field
data
field
scale.
the
The
to near background values during trickle
magnetic
off
antennas.
both
data show 20 - 30 dB increases in amplitude
return
The
of
Hz to 3.0 kHz range with the ion beam on.
400
amplitudes
channels
kHz
3.0
field
the
peaks
Both periods are clearly seen on the 0.4,
period.
shows that at 400 Hz the
than
1.3
-
40 dB and the signal
3.0 kHz channels show
increases of 35 - 40 dB.
During
mode the magnetic field amplitudes show a decrease,
but
remain
as
showing
frequencies
15 - 30 dB above background.
that
by
the
no
interference
gun
during
trickle
We interpret this
generated at these
mode reaches the
electric antenna, but that an electrostatic or
electromagnetic
signal
is caused by the interaction of the
'dense' xenon plasma from the gun with the ambient plasma in
the
this
100
immediate vicinity (a few meters) of the satellite, and
signal
kHz
strength
to
the
is
observed by the magnetic loop antenna.
The
electric field channel shows an increase in signal
during trickle mode.
This frequency is comparable
upper hybrid resonance or the plasma frequency near
the satellite.
39
.
B.
APRIL 1979
2
on
1513 - 1548 UT
The
second operation we shall present occurs in eclipse
Day
92 of 1979.
Plasma wave response to gun operations
appear similar to those observed in the dusk bulge region on
This example illustrates typical observations for:
day 200.
high voltage and neutralizer on.
- gun,
-
gun and high voltage on, neutralizer off.
-
gun on, high voltage and neutralizer off (trickle mode).
-
gun off.
During
this period the satellite is between L = 7.3 and 7.6
and the time is just after local midnight.
in
The electron cyclotron
from 1430:00 - 1537:53.
eclipse
The satellite is
frequency varies from 3.2 to 3.6 kHz, the hydrogen cyclotron
frequency
varies
about
is
from
75
data
narrowband
to
for
Hz,
2
85
and the lower hybrid frequency
Only
Hz.
this
period
the
spectrograms
are shown.
and
Attempts to
generate amplitude plots for the frequency spectrum were not
because of the age of the magnetic tape on which
successful
the
data was stored.
the
0-5
Therefore,
The data for this period was taken in
kHz receiver mode, but only
no
receiver
roll-off
at
3
0-4
kHz is shown.
kHz occurs for this
data
This
voltage
with
data
at
1
set
begins
with
the ion beam on with beam
kV and beam current at 1.0 mA; neutralizer on
neutralizer current at 1.2 mA and the neutralizer bias
^0
level
-10 V.
at
Hence,
spacecraft,
the
data
field
the
signal
are
regularly
from
Examination
2
kHz region showing slightly greater
A faint spectrum exists in the electric
- 1.5 kHz.
0.4
during
seen
continuous band of signals
The 700 Hz and 2100 Hz interference lines
visible.
data
field
-
strength.
not
a
The magnetic
kHz to the top of the spectrogram at 4 kHz
1
kHz
1
charges positively.
it
Figure 18 show
in
from just below
with
and
there is a net positive current to
This diffuse spectrum is
neutralized
such
beam operations.
of filter data (presented below) show that this
amplitude has increased relative to the gun off data
signal
(also presented below).
Figure
off
data
shows how arcing occurs with the neutralizer
19
(neutralizer
Day
from
off at 1517:47).
200
same gun settings.
the
at
This data resembles the
The broad
frequency spikes and the intense 1.0 - 1.5 kHz band are both
present in the magnetic field data.
The electric field data
appear similar to the arcing data shown for day 200.
20
I.
setting,
as the high voltage is turned off at
The gun enters trickle mode at that point.
1518:50.
that
taken
data
shows
=
and
1.0
mA
hence
reflects
ionization
emitted current is only 10
time
in
Figure
- 20
the
beam
rate
discharge current
in the chamber.
microamps).
(Note
The
Visible at this
the magnetic field data are the 700,
1400 and 2100
Hz interference lines and the diffuse background noise.
The
electric field data contains a very low frequency (less than
m
K-Er*
ON
OFF H
IGP
HV
ON
OFF H
NP
ON
OFF H
V.
2kV A
lkV
b
f—
1513:00
-
2
.0mA
-
1.0mA -—
0.3mA -
n
2
1
2mA
.2mA
.
0.4mA
-
-
-
0V
NBL -10V
-25V
-100V
-|
-I
Figure 18.
Spectrogram of the period 1512:5^
1513:28 2 April 1979.
42
-
^— b^K
(kHz)
IGP
ON
HV
ON
NP
ON
V,
b
2kV H
lkV
I,
1.0mA
I
1
D
n
B
-H«-=-
.2mA
0V
-
NBL -10V
-25V
-100V
-
Figure 19.
Spectrogram of the period 1517:22
1518:02 2 April 1979-
^3
-
M
—
K
(kHz)
*K
*K
B
*l
-L%.
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—
5£%##sg»
JjJiU'wfcj^JLjJixiii^iV
q
IGP
HV
±
ON
OFF
ON
OFF
1518:50
-
NP
ON
OFF
V.
2kV H
lkV
b
",.-t
!
-
-
2
.0mA
1.0mA
D
0.3mA
-
I.
-
-
2
I
.2mA
1.2mA
n
0.4mA
0V
NBL -10V
-25V
-100V
-
-I
Figure 20.
Spectrogram of the period 1518:37
1519:16 2 April 1979.
44
-
100 Hz) signal and some spotty signals near one kHz.
shows
21
which
fluctuations
further
apparently
are
magnetic
data
field
due
to
continue
Figure
in the electric field data
ambient
plasma waves.
The
show the broad, diffuse
to
spectrum.
The
while
the
1400
Since
these
their
disappearance could again be caused by changes in the
broad
background amplitude or by attenuation of the signals
the
in
turned
2100
are presumably of constant amplitude,
arcing
that
data
field
neutralizer
1.2
at
are
similar
after
those
and bias level -100 V.
mA
delay
is not seen in similar data).
to
changes
level
shown
almost
level
changes
Neutralizer
presenting
23.
here.
made
during
the
bias
level
time
Four bias
period we are
In all four cases there was no detectable
in the magnetic field data.
change
a
made during neutral beam emission have
no effect on the plasma wave data.
were
(Note time
The characteristics of
the field data is now the same as in Figure 18.
bias
already
an error in the command log as this
may
due
to
1521:15 turn on of the
the
delay
be
when the high voltage is
The arcing signature ceases in Figure
seconds
few
a
resumes
Figure 21
The characteristics of the electric
at 1520:05.
on
presented for arcing.
22
Hz lines can no longer be seen.
xenon plasma cloud around the satellite.
magnetic
and
and
signals
shows
also
700 Hz interference line is barely visible,
change from -100 V to
Plasma wave data during
V is shown in Figure
The electric field data now shows some fine structure.
^5
—
(kHz)
k
?k
^
B
fH
O
3
a?
o
IGP
ON
OFF
HV
ON
OFF
-
NP
ON
OFF
-
V.
2kV
lkV
-
.0mA
.0mA
-
0.3mA
-
b
2
1
1520:05
-
-
-
.2mA
-
1.2mA
0.4mA
-
2
I
n
0V
NBL -10V
-25V
-100V
-
-I
Figure 21.
Spectrogram of the period 1519:^+
1520:2^ 2 April 1979-
k6
-
K
(kHz)
I
W
*
B
3-—in,
;
,.i
l!M
i
* B^
i
j
IGP
HV
ON
OFF
ON
OFF
j.
-^^mj
•
-
NP
ON
OFF
-
V.
2kV
lkV
-
b
j
-
.0mA
-
1.0mA
0.3mA
-
2
I
-
.2mA
-
1.2mA
0.4mA
-
2
I
n
-
0V
NBL -10V
-25V
-100V
-
-«
Figure 22.
Spectrogram of the period 1520:58
1521:38 2 April 1979.
^7
-
B
(kHz)
ON
OFF
IGP
HV
NP
V
>K-
^H— b-H
1522:18
ON
OFF
-
ON
OFF
—
2kV
IkV
b
.0mA
.0mA
3mA
2
b
.
I
n
2
1
.
2mA
.2mA
.4mA
0V
NBL -10V
-
-25V
L00V
Figure 23.
Spectrogram of the period 1522:00
1522:^0 2 April 1979.
^3
-
lowest
The
about
is
300
and
Hz
the
Similar
seen at other times when the bias level was
were
results
signal
spacing between signals is about 170 Hz.
frequency
level changes between different negative voltages
Bias
V.
frequency
had no effect on the electric field data.
At 1540:30 the satellite is no longer in eclipse and the
ion gun power is turned off.
shown
is
interference
data.
Figure
in
The
24.
700,
1400 and 2100 Hz
are again visible in the magnetic field
lines
signals
No
Plasma wave data for this time
visible in the electric field data
are
after the gun is turned off.
operation
This
narrowband
-
The
1600
two trickle mode
mode
on
as
analyze
to
day
200.
because
Other mode changes are
they were done over a short
compared to the time scale of Figure 25.
period
and
Figure 25.
The electric and magnetic field data responded
trickle
difficult
were
there
time
this
operations.
to
in
data is shown for the period 1400
filter
During
UT.
summarized
is
The 10 kHz
frequency channels show large amounts of signal
higher
day
200 data (Figure 17)
showed these bands to be much quieter.
This signal activity
activity
correlates
satellite
exists
lower
these
in
well
was
bands.
The
the
period of time during which the
in eclipse.
Assuming that this 'noise' also
with
the
frequency channels lower than 10 kHz, these
channels
would be difficult to analyze even with the
in
time scale expanded.
^9
*
K— b— 4
(kHz;
B
4-
O
ON
OFF
IGP
1
1540:30
ON
OFF
HV
NP
ON
OFF
V.
2kV
lkV
b
-
-
-I
-I
2.0mA
-
.0mA
-
1
0.3mA
-
n
2mA
-
.2mA
-
0.4mA
-
2
1
.
0V
NBL -10V
-25V
-100V
-»
Figure 24.
Spectrogram of the period 1540:14
1540:56 2 April 1979.
50
-
H
—
I
h
I
r
I
SCATHA
AEROSPACE RECEIVERS
APRIL 1979
2
SCI-8A
ANTENNA
ELECTRIC
————————
i
~i
40. Of-
i
I
i
i
i
i
I
I
I
4-
1
I
-40.0
1
I
i
i
i
r
i
^W^^/T-^
— — —exit —eclipse
——
-70
i
i
i
enter eclipse
i
I
i
— ————————
1
I
I
I
4-
I
I
I
i
I-
exit eclipse
-50
-60.0
-70
"""
-f""^
mode
— — — —trickle
t—h— — — —
H
o
i
enter eclipse
O -500s -«o.oF
o
o
i
ANTENNA
MAGNETIC
»
-40.0
-50.0
l
I
I
I
i
I
N
-"- "
I-
H
1
1
1
-70.0
1
1
1
1
1
h
trickle mode
j#M^
-60
1
GQ
LU
Q
\-
O
-I
CL
CM
rO
*•
-500
50400
14 00 00
15
50400
14 00 00
54000
00 00
UNIVERSAL TIME
Figure 25.
Narrowband filter data for
li+00 - 1600
2 April 1979.
51
54000
15 00 00
(SEC)
.
SUMMARY OF OBSERVATIONS
C.
Broadband
narrowband plasma wave data taken during
and
gun operations conducted on several different days were
ion
surveyed.
Data presented above were chosen to show typical
responses
observed
response
dependence
Emission
ion
to
non-neutral
gun
operations
did
not
Plasma
show any
satellite location within the magnetosphere
on
of
a
neutralized ion beam produced near zero
potentials
satellite
and
beam emissions and during trickle mode.
accelerated
wave
neutral
during
(slightly
electron current than ion current).
positive
due to higher
The plasma wave data at
such times show broadband signals recognized as the receiver
response
to
white
a
noise input and occasional naturally
occurring signals.
Non-neutralized
of negative charging on the satellite.
effects
the
beam operations were conducted to study
Plasma
wave data during these emissions show that for beam currents
of
1
mA and higher, differential charging induced arcing is
occurring.
Operation
dense
No
data
cloud
Xe
to form in the vicinity of the satellite.
arcing occurs during this operating mode.
shows
magnetic
the
of the ion gun in trickle mode causes a cold,
that
field
electric
white
antenna
field data.
noise
is
being
The broadband
received
by the
and only natural signals appear in
Examination of narrowband filter
52
data
for
mode shows that input to the electric field
this
antenna at 30 kHz and below is at gun-off background levels,
the magnetic field antenna is still receiving signals
while
with
amplitudes
whatever
interfere
electric
shielding
signals
signals
with
field
of
due
20
-
are
above
dB
30
generated
plasma
antenna.
wave
background.
near the satellite do not
observations
In
Hence,
addition,
with
there
the
should
long
be
the electric antenna from satellite generated
to attenuation in the Xe
53
cloud as shown next.
CALCULATIONS
IV.
Propagation of electromagnetic waves through
a
plasma is
a
In general, many simplifing
complex situation to analyze.
assumptions are needed to allow solutions to be obtained. In
estimate
order
to
near
the
-
attenuation of low frequency waves
the
satellite
assume
shall
we
the following:
wave frequency much exceeds the xenon ion cyclotron
frequency (f>>f .).
- no
pressure gradient effects (cold plasma).
- no
external magnetic field (B
-
The
zero intrinsic impedance (collisionless plasma).
density
around
hollow
experimental
density
expected
density
data shows
at
seen
1
profiles
is
to
m
known but can be estimated.
not
profiles as measured in a
density
shown
cathode
is
is
cathode
are
laboratory
the
trickle mode of the xenon plasma cloud
during
satellite
the
Typical
from
=0).
in
a
Figure
26
(Ref.
This
24).
typical density a few centimeters
between
fall-off
10
7
cm
—3
sharply
to be about 10
5
cm
—3
and 10
with
to 10
8
cm
—3
.
density
the
6
—3
cm"
The
.
These
should be comparable to those for the ion
gun operated at geosynchronous orbit.
5^
A
10=
Z\— A
run
0--0
RUN 2
1
i
^
10
CO
o
g
a:
Eh
O
w
10
&
o
—
io-
25
50
75
100
PRGBE TC CATHODE DISTANCE (cm)
Figure 26.
"Typical" hollow cathode density
profiles in laboratory.
55
125
150
dispersion relation for electromagnetic waves using
The
the assumptions made above is
c
S
2
1
where
frequency,
light
in
plasma
the
kHz.
a
2
/6J
is the plasma frequency,
and c is the speed of
vacuum
For our situation the
frequency
(Refs.
25,26).
on the order of 10 kHz to 100 kHz and
is
wave frequencies we are concerned with are less than 10
When
frequency
attenuated
over
M
-6J p
velocity in the plasma, 6J is the wave
is the phase
v
2
wave
the
frequency
the medium.
in
than the plasma
velocity is imaginary and the wave is
phase
the
less
is
If d is defined as the distance
which the wave amplitude decreases by a factor of l/e,
then
c
1
d =
L0 p
Using
(Ref. 26).
r
(i
2
-CO
/^
2
1
)
this expression one obtains the following attenuation
distances (for 700 Hz).
n (cm
10
10
10
10
10
d
)
4
(m)
53
5
17
6
5.3
7
1.7
8
0.5
56
.
Densities
of
cm
10
to
would be consistent
cm"
10
with available laboratory data, observations of signals near
kHz
100
is
100
in the electric field data (xenon plasma frequency
kHz
for
n
=
3
A6
of the interference lines.
x
10
7
1/cm 3
),
and the attenuation
The actual xenon density profile around the satellite is
known,
not
and
attenuation
not
is
possible to verify that
The disappearance of
interference lines from the magnetic field
during trickle mode could simply be an artifact caused
data
by
it
is actually taking place.
tuning-fork
the
thus
the
AGC
.
However,
it
is
consistent with theory and
observation that low frequency wave attenuation by the dense
xenon
cloud
generated during trickle mode is improving the
data
57
.
CONCLUSIONS
V.
emission
positive
The
system
satellite showed that
SCATHA
a
experiment on board the
neutralized ion beam is very
effective in discharging a differentially charged satellite.
However,
the
plasma
arcing
that
result
can
non-neutralized
wave experiments on board SCATHA show
from
the
operation
of a
Some major points of interest in
ion beam.
the data are:
arcing seen during emission of accelerated ions
without neutralization depends on the beam current, with
more frequent arcing at higher beam current.
- The
If
-
Arcing ceases when the acceleration voltage is turned
off, while the gun is still emitting ions.
-
Arcing ceases when the neutralizer is turned on.
-
A broadband (1-2 kHz) signal exists on the magnetic
antenna during trickle mode but not on the electric
antenna
-
Intense low (<100 Hz) frequency signals seen in the
electric field data with the gun off and during
non-neutralized beam emissions are not seen during
neutralized beam emissions.
arcing, is due to differential charging it is clear
the
that it would be a function of the beam current level.
trickle
means
mode
of
and
discharging
arcing to cease.
caused
by
neutralizer
the
operations
satellite
Both
would provide a
causing
the surface
For these reasons we believe the arcing is
differential
charging of the satellite surface.
58
signals
The
trickle
mode
seen
magnetic
the
in
field data during
could be associated with plasma turbulence or
ion
acoustic waves in close proximity to the satellite.
is
not
clear
these
if
It
signals are electrostatic or
electromagnetic (Ref. 12).
broad
The
-
(1
2
gun operations.
ion
kHz) signal is regularly seen during
This signal is apparently the receiver
response to a white noise input.
emission
The
to
of a neutralized ion beam, which is known
provide control of spacecraft charging, was found not to
plasma
generate
which
waves
might interfere with the
experimental observation of ambient signals.
that
the
emission
of
a
It is possible
sufficiently dense, cold, neutral
plasma (trickle mode with neutralizer on, bias level at
could
dipole
allow
the
antenna)
shielding
from
of
satellite
antennas (such as the SC10
interference
allowing for control of satellite charging.
59
V)
while still
)
APPENDIX
TABLE
1
SCATHA SATELLITE EXPERIMENTS
Exp
Id
SCI
Parameters Measured
Title
Engineering Experiments
Plus VLF and HF Receivers
(1
(2
(3
(4
SC2
Spacecraft Sheath Fields
Plus Energetic Ions
(1
(2
(3
(4
Surface potentials
of various materials
EM VLF wave analyzer
(a few Hz to 300 kHz)
EM RF wave analyzer
(2 MHz to 30 MHz)
Transient pulse
shape analyzer
Potentials of spherical probes
Low energy electrons
and ions (15 eV/q to
18.6 keV/q)
Energetic protons
(17 keV to >3.3 MeV)
Energetic ions 1>2
(E >90 keV/neucleon)
SC3
High Energy Particle
Spectrometer
High energy electrons
and protons (E =50 keV
e
to 5.3 MeV, E = 1.0 MeV
P
to 200 MeV)
SC4
Satellite Electron and
Positive Ion Beam System
(1)
Electron beam emission system E =50
eV to 3.0 keV? I =
e
(2)
Positive ion (Xenon)
beam emission system
= 1.0 and 2 .0
(E
x
= 0.3 mA
keV; I
to 2.0 mA
1.0/A.A to 13 mA)
SC5
Rapid Scan Particle Detector
60
Electrons and ions
= 50 eV to
1.0 MeV;
(E
e
=50 eV to 35 MeV)
E
)
TABLE
Exp
Id
SC6
1
Continued.
-
Parameters Measured
Title
Thermal Plasma Analyzer
Thermal electrons and
ions (E & E T from
eV t§ 100 eV)
SC7
Light Ion Mass Spectrometer
Light ion density, temperature and composition
(£
H
SC8
Energetic Ion Composition
Experiment
(1)
= 0_.0 £o 100 eV;
T
He
o
)
Ion composition of
energetic plasma
(E
=
100 eV to 32 keV; M =
0.8 to 160 AMU with M/Q=
1,2,4 or 16)
(2)
(E
Low energy electrons
= 70 eV to 24 keV
in 4 channels)
SC9
UCSD Charged Particle
Experiment
Electrons and ions (one
set with E = few eV to
81 keV, two others with
E = 0.2 eV to
1.55 keV)
SC10 Electric Field Detector
DC and ELF electric
fields and satellite
potential (ELF 0.2 to
200 Hz; common mode
voltage
to + 5 keV)
SC11 Magnetic Field Monitor
DC and ELF magnetic
field (range from
+ 0.3 to + 500 nT;
ELF about 1 to 100 Hz)
ML12 Spacecraft Contamination
Plus Thermal Control
Materials Monitoring
Contaminant mass
1
deposition rates
(2) Solar absorptance
of test materials
TPM
(
Electromagnetic pulse
environment on satellite
(Pulse amplitude 2 mV to
240 V, current 2 mA to
Transient Pulse Monitor
1700 A)
61
..
TABLE
2
SC4-2 ION GUN COMMANDS
Function
Command
1
Instrument on
Turns on instrument power
2.
Instrument off
Turns off all instrument power
3.
Expellant valve open
Opens solenoid valve
4.
Expellant valve closed
Closes expellant valve
5
Cathode heater preheat
Turns on the cathode to Level
1 and turns on discharge
supply
6.
Ion gun power on
Turns on the ion gun power
7.
Ion gun power off
Turns off the ion gun power
8.
Beam voltage Level
1
Sets the beam power supply to
1000 V
9.
Beam voltage Level
2
Sets the beam power supply to
2000 V
10. Keeper off
Turns the keeper supply off
11. Discharge current and
Sets the discharge current
reference to achieve 20 mA
current; sets neutralizer
emission level to 0.4 mA
neutralizer emission
Level 1
12. Discharge current and
neutralizer emission
Level 2
13. Discharge current and
neutralizer emission
Level 3
14. Neutralizer emission
Level 4
Sets the discharge current
reference to achieve 125 mA
current; sets neutralizer
emission level to 1.2 mA
Sets the discharge current
reference to achieve 200 mA
current; sets neutralizer
emission level to 2.2 mA
Sets neutralizer emission
level to 2 l\K
62
TABLE
2
-
Continued.
Function
Command
15. Neutralizer emission
Level
5
16. Neutralizer No.
1
Sets neutralizer emission
level to 20 .HA
Selects neutralizer filament
No.
17. Neutralizer No.
2
1
Selects neutralizer filament
No 2
18. Neutralizer heater on
Turns on the neutralizer
cathode heater
19. Neutralizer heater off
Turns off the neutralizer
heater
20. Neutralizer bias off
Turns off the neutralizer
bias power supply
21. Neutralizer bias
Sets the neutralizer bias
for positive polarity
positive
22. Neutralizer bias
negative
23. Neutralizer bias
Level
1
24. Neutralizer bias
Level
2
25. Neutralizer bias
Level
3
26. Neutralizer bias
Level 4
27. Neutralizer bias
Level
5
Sets the neutralizer bias
for negative polarity
Turns on the neutralizer
bias to 10 V
Turns on the neutralizer
bias to 25 V
Turns on the neutralizer
bias to 100 V
Turns on the neutralizer
bias to 500 V
Turns on the neutralizer
bias to 1000 V
28. High voltage off
Turns off the beam and accel
power supplies
29. Cathode conditioning
Turns on the cathode heater
63
LIST OF REFERENCES
1.
Olsen, R. C, "Observations of Charging Dynamics," Journal of Geophysical Research v. 88, p. 5657, 1 July
1983.
,
2.
Grard, R., Knott, K. and Pedersen, "Spacecraft Charging
Effects, " Space Science Reviews v. 34, pp. 289-304,
1983.
,
3.
Garrett, H. B., "The Charging of Spacecraft Surfaces,"
Reviews of Geophysics and Space Physics v. 19, pp. 577616, November 1981.
,
4.
Whipple, E. C, Potentials of Surfaces in Space pp. 165, University of California at San Diego, La Jolla,
California, February 1981.
5.
Kintner, P. M. and Kelley, M. C., "Plasma Waves Produced
by the Xenon Ion Beam Experiment on the Porcupine Sounding Rocket, " in Artificial Partical Beams in Space Plasma Studies pp. 199-205, edited by Grandal, B., NATO
Advanced Study Institute Series, Series B, v. 79, 1982.
,
,
6.
Kintner, P. M. and Kelley, M. C, "Ion Beam Produced
Plasma Waves Observed by the Delta n/n Plasma Wave Receiver During the Porcupine Experiment, " in Advances in
Space Research, Active Experiments in Space Plasmas v.
1, n. 2, pp. 107-115, edited by Russell, C. T. and
Rycroft, M. J., Pergamon Press Ltd., Oxford 0X3 0BW,
England, 1981.
,
7.
Kintner, P. M. and Kelley, M. C, "A Perpendicular Ion
Beam Instability: Solutions to the Linear Dispersion
Relation," Journal of Geophysical Research v. 88, pp.
357-359, 1 January 1983.
,
"Xe -Induced Ion-Cyclotron Harmonic Waves,"
in Advances in Space Research, Active Experiments in
Space Plasmas , v. 1, n. 2, pp. 103-106, edited by
Russell, C. T. and Rycroft, M. J., Pergamon Press Ltd.,
Oxford 0X3 0BW, England, 1981.
8.
Jones, D.,
9.
Walker, D. N., "Perpendicular Ion Beam-Driven Instability in a Multicomponent Plasma: Effects of Varying Ion
Composition on Linear Flute Mode Oscillations, " Journal
of Geophysical Research v. 91, p. 3305, 1 March 1986.
,
6/+
"
10.
Hudson, M. K. and Roth, I., "Thermal Fluctuations From
an Artificial Ion Beam Injection Into the Ionosphere,"
Journal of Geophysical Research v. 89, pp. 9812-9813,
1 November 1984.
,
11. Erlandson,
R. E., and others, "Initial Results From the
Operation of Two Argon Ion Generators in the Auroral
Ionosphere," Journal of Geophysical Research v. 92, pp.
4601-4608, 1 May 1987.
,
12. Haerendel, G. and Sagdeev, R. Z., "Artificial Plasma Jet
in the Ionosphere," in Advances in Space Research, Active Experiments in Space Plasmas , v. 1, n. 2, pp. 2946, edited by Russell, C. T. and Rycroft, M. J.,
Pergamon Press Ltd., Oxford 0X3 0BW, England, 1981.
13.
Roth, I., and others, "Simulations of Beam Excited Minor
Species Gyroharmonics in the Porcupine Experiment,
Journal of Geophysical Research v. 88, pp. 8115-8122,
1 October 1983.
,
14.
Fennell, J. F., "Description of P78-2 (SCATHA) Satellite
and Experiments, " in IMS Source Book pp. 65-78, AGU,
Washington D.C., 1982.
,
15. Olsen,
tudes
,
R. C., Electron Beam Experiments at High Altipaper presented at NATO meeting, June 1986.
16. Air Command and Staff College, Air University, Maxwell
Air Force Base, Space Handbook p. 1-13, Government
,
Printing Office, Washington, D.C., 1985.
17. Masek,
T. D.
Beam System,
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,
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3il
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89?
DUDLEY KNOX
Thesis
W33285
c.l
Meddle
Ion gun generated
electromagnetic interference on the SCATHA
satellite.
I