Several programs and variations have been developed to determine statistical means of different plasma parameters when binned in different variables. These parameters include temperature, densities and spacecraft potentials for any of the ion species, as well as ratios of these variables for any other ion species to the corresponding variable for H(+). The variables for binning include L, radial distance, and geomagnetic latitude; and separate statistics are automatically run for local morning and local evening data. These programs all run from output files from the plasma parameter thin sheath analysis program. A variant program also bins for magnetic activity, using either Kp or Dst, which requires an additional magnetic activity input file. These programs can be run either interactively or in batch mode, using file listings generated by a DIRECTORY command. In addition to printed output, these programs generate output files which can be used to plot the results. Programs to plot these averaged data are under development

Comfort, R. H.

Horwitz, J. L.

English

Research activities on the following topics were summarized: (1) software for the Space Plasma computer Analysis Network (SPAN), (2) plasmaspheric field-aligned temperature gradients, (3) the shift in spacecraft potential as a function of plasma density, (4) plasma flow, (5) the Fabry-Perot interferometer, and (6) the Differential Ion Flux Probe (DIFP)

NASA Technical Reports Server

.. 
. ' 
QUARTERLY PROGRESS REPORT 
NASA_CR-171080 
19840021305 
Contract NAS8-33982 
PLASMA AND MAGNETOSPHERIC RESEARCH 
March 1984 - May 1984 
by 
Richard H. Comfort 
and 
James L. Horwitz 
Prepared for 
National Aeronautics and Space Administration 
George C. Marshall Space Flight Center 
Marshall Space Flight Center, Alabama 35812 r ;~rij 0 !illl! 
LdLltilHlil U 
Submitted by 
The University of Alabama in Huntsville 
School of Mathematical and Natural Sciences 
Huntsville, Alabama 35899 
June 1984 
1111111111111 11\11111111111111\11111111111111 
NF02666 
: . .' 2 :i 19H4 
U-\NGLEY RESEARCH ,; -I', r'K 
LIBRARY, NASA -
HN.~PTO~L YJRGINIA 
https://ntrs.nasa.gov/search.jsp?R=19840021305 2020-03-20T22:31:47+00:00Z
ANALYSIS TECHNIQUES AND SOFTWARE DEVELOPMENT 
We have been cooperating with Tom Moore in the development of 
practical techniques for treating calibration and saturation problems. Low 
altitude data from 1981 day 314 was analyzed with the RPA analysis program 
and with the spin curve program to compare with the electrometer data. 
Both the calibration and saturation problems must be addressed 
simultaneously since the electrometer is sensitive primarily when 
saturation is likely to occur. When the program (under development) which 
incorporates the inline calibration and compensates for the saturation 
effects is completed, the RPA analysis program must be modified to 
incorporate the new program in the data preparation part. 
In the previous report an apparent enhancement in z head 
efficiencies at energies below 1 eV was noted. Based on a study of the 
construction of the RPA by Alan Biddle, this enhancement has been 
tentatively ascribed to a "lens focusing effect" at the electrometer 
aperture. 
A computer program has been written to determine particle velocity and 
size from contamination particulates observed by the Induced Environmental 
Contamination Monitor (IECM). 
We are participating in the development of software for the Space 
Plasma computer Analysis Network (SPAN) scientific work station. This also 
includes the development of software facilities for producing and accessing 
META code graphics files. 
Dennis Gallagher is now the chairman of the Software Standards 
subgroup of the Data System Users Working Group (DSUWG). This group is the 
formal advisory organization for SPAbl, which has been designated a NASA 
pilot project. SPAN has grown to become the most successful of all NASA 
:3 
sponsored scientific data analysis networks, joining researchers in space 
plasma science at 14 institutions throughout the United States, and 
projected to double in size in the next year. 
Dr. Gallagher also continues to serve on the SSL computer committee, 
acting as 'one of several advisors regarding the development of SSL computer 
facilities. 
SATELLITE DATA ANALYSIS 
In order to look for plasmaspheric field-aligned temperature gradients 
in the early RIHS data, we have plotted both the high and low altitude 
parts of the temperature profile together as a function of L (dividing at 
the minimum L shell) • An interesting finding is that during 
geomagnetically quiet times, the high altitude plasmasphere either is in 
thermal equilibrium with lower altitudes (inner L shells for local 
morning) or acts as a heat source for lower altitudes (outer L shells in 
local morning, all L shells in local evening). During disturbed times, 
however, this balance shifts so that the high altitude plasmasphere can 
either be in equilibrium with low altitudes (local evening) or cooler than 
low altitudes (local morning). Comparisons of the ion temperature profiles 
indicate that this is not due to heating at low altitudes, but to depressed 
temperatures at high altitudes during magnetically active periods. This 
could result from either enhanced cooling or decreased heating at high 
altitudes during active times. These results have been incorporated into 
the draft of the paper on DE l/RIMS ion temperatures (Ref. 1). 
The PC-S paper with Hunter Waite (Ref. 2) has now been sent to all 
interested parties, prior to submission for publication. Special caution 
is being used with this paper because our results contradict published 
4 
results by Cahill et al. We interpret the combined measurements of RIMS 
and the PWI static electric field instruments to indicate that a PC-5 wave 
structure from the dayside magnetossheath passed by the DE 1 spacecraft, 
rather than DE 1 passing through a stationary wave structure. Some of the 
amplitude variations are also being interpreted as due to spatial structure 
in the wave resonance, rather than entirely due to temporal variations in 
the wave source. The resulting picture of the wave structure in the 
magnetosphere is very interesting, and we are now trying to have our 
interpretation rendered in an artist's drawing. 
The study of high densities and ion outflows from the polar cap has 
concentrated on analyzing a single event. Conclusions from studying that 
event are that there exists a population of 15-20 cm-3 of purely convecting 
+ + -H , a population of 5-10 cm-3 of flowing and convecting Hand 20-25 cm 3 
of flowing and convecting 0+. The flowing ions are highly collimated 
within a solid angle of ±S degrees and, including the convection, have a 
direction of ~135° with respect to the geomagnetic fie]d. These results 
were presented to the Spring AGU Meeting (Ref. 3) and a paper detailing 
them is in preparation (Ref. 4). Work on a follow-on study has begun to 
identify other passes with similar features during the lifetime of HAPI. 
The second study will focus on statistical information and morphology. 
SCATHA measurements of radial electric fields observed during eclipse 
(at local midnight) have been analyzed for most of the 1979 events. 
Preliminary results were presented to the Spring AGU Meeting (Ref. 5). A 
paper on this topic is in the rough draft stage (Ref. 6). 
An effort is being made to analyze a substantial portion of the 
available plasmasphere data for temperatures and densities for the period 
when the RU1S radial RPA was functioning properly. All available data for 
5 
the period of only H+ and He+ observations (Day 280 to Day 290, 1981) have 
been analyzed. Data files containing temperatures, densities and 
spacecraft potentials are being stored on a PDP disk to serve as a data 
base for future studies. Selected sets of data are being plotted versus 
invariant latitude for correlation with Brace's DE 2/LANG ionospheric 
electron densities .and temperatures. Other data sets are being used to 
examine plasmasphere structure and its relation to local time and magnetic 
activity history. 
A study has been initiated to determine sub storm characteristics, 
primarily rise and fall time constants, for steady IMF intervals. 
'ole have participated in analysis of data obtained during the STS-3 
space shuttle mission. Some results of this analysis will be reported in a 
paper being prepared for submission to GRL (Ref. 7). 
The study on the relationship of the dusk sector electric field to 
electron energy dispersion was completed. Results were presented to the 
Spring AGU Meeting (Ref. 8) and submitted for publication (Ref. 9). The 
initial study of a period of plasmasphere filling was also concluded, and 
the results submitted for publication (Ref. 10). Work on the heavy ion 
enhancement study with Torn Roberts, has continued. 
Data for 1981 Days 295 and 296 was analyzed and densities and 
temperatures were sent to Janet Kozyra for her study of SAR arcs and ring 
current decay. The periods were times of ion cyclotron events reported by 
Don Gurnett at the last DE meeting. 
6 
SPACECRAFT SHEATH EFFECTS 
The distribution function technique has been applied to a number of 
eclipse passages in the 1982 eclipse season in order to determine the shift 
in spacecraft potential as a function of plasma density. Potential shifts 
of about 0.5 V typically correspond to densities near 200 cm-s , with larger 
shifts found for lower· densities. These transitions have also been 
examined using spin curve techniques. The combination of the RPA curves 
from the end heads and the spin curves from the radial detectors provides 
the opportunity to obtain absolute potentials, as well as the shift. 
Preliminary results show the same shift in potential, but disagreement on 
the potentials of the different detector assemblies. During this period, 
the radial detector appears to be 0.5 to 1.0 V less positive than the -z 
detector, with the +Z detector maintaining its 2 V negative bias with 
respect to the -Z detector. 
LABORATORY PLAS}~ FLOW STUDIES 
A new Langmuir probe has been constructed and is to be mated with an 
electronic circuit to accommodate fast voltage sweeps. Following 
correction of problems with circuit components, the electronics for this 
probe will be tested with another Langmuir probe. Once successful testing 
has been completed, the new probe should provide satisfactory measurements 
of electron and ion temperatures for the plasma flow experiments. 
Results of previous experiments on the plasma expansion process are 
being reported in several forums. Some of these experimental results will 
be reported by Uri Samir in a poster paper at the 1984 International 
Conference on Plasma Physics, with a summary paper to be published in the 
conference proceedings (Ref. 11). The final draft of the paper on the 
7 
plasma wake experiments is being completed for submission to JGR (Ref. 12). 
A paper on the expansion of space plasmas into a vacuum will also be 
presented to the URSI meeting (Ref. 13). 
REMOTE OBSERVATIONS 
John Bird travelled to College, Alaska to work with Gary S,.;renson in 
obtaining data to provide thermospheric temperatures and winds, using the 
Fabrey-Perot interferometer. Modifications to the instrument were 
successful, and a considerable amount of data was taken. Programs to 
analyze the data are being developed. 
INSTRUMENT DEVELOPMENT 
A number of test fixtures were designed and built for the large vacuum 
chamber. Parts were fabricated for Differential Ion Flux Probe (DIFP) 
heads. A substantial part of the design and fabrication of the dual ion 
source was completed. 
PRESENTATIONS AND PUBLICATIONS 
Drs. Gallagher, Horwitz, and Olsen travelled to the Spring AGU Meeting 
in Cincinnati, OH, where they presented papers (Refs. 3,8,14). In 
addition to those, a paper on the p1asmaspheric bulge region was presented 
by Pierette Decreau (Ref. 15). Dr. Olsen will present a paper to the URSI 
meeting in Italy (Ref. 16). 
In addition to the papers noted above, the following are at the 
indicated stage of the publication cycle. 
Papers published: a report of the p1asmapause meeting (Ref. 17); the 
initial report on the dusk sector relation between electric field and 
8 
electron energy dispersion (Ref. 18); the paper on diffusive equilibrium 
+ distributions of He in the plasmasphere (Ref. 19); and the Finland 
Workshop paper (Ref. 20). 
Papers accepted and in press: a study on the implications of solar 
flares for substorms (Ref. 21); a paper on residence time heating effects 
on auroral conic generation (Ref. 22); the paper on magnetospheric plasma 
dynamics (Ref. 23); the supersonic polar wind paper (Ref. 24). 
Papers submitted and under review: the paper on magnetosheath 
electrostatic waves (Ref. 25). 
Papers in preparation: the equatorial heating paper (Ref. 26); the 
plasmapause review paper (Ref. 27). 
R. H. Comfort 
. / <-..-) 
tho L. Horwitz 
" 
9 
REFERENCES 
1. Comfort, R. H., J. H. lolaite, Jr., and C. R. Chappell, Thermal ion 
temperatures from the Retarding Ion Mass Spectrometer on DE 1, to be 
submitted to J. Geophys. Res., 1984. 
2. Waite, Jr., J. G., J. F. E. Johnson, C. R. Chappell, D. L. Gallagher, 
R. C. Olsen, R. H. Comfort, D. Weimer, S. D. Shawhan, W. K. Peterson, 
and E. G. Shelly, Plasma and wave observations of a PC-5 wave event, 
to be submitted to J. Geophys. Res., 1984. 
3. Gallagher, D. L., J. D. Menietti, A. M. Persoon, J. H. Waite, Jr., and 
C. R. Chappell, Evidence of high densities and ion outflows in the 
polar cap during the recovery phase, EOS, Transaction of the American 
Geophysical Union, ~, 256, 1984; pres;nted to the Spring Meeting of 
the American Geophysical Union, Cincinnati, OH, May 14-18, 1984. 
4. Gallagher, D. L., J. D. Menietti, A. M. Persoon, J. H. Waite, Jr., and 
C. R. Chappell, Evidence of high densities and ion outflows in the 
polar cap during the recovery phase, to be submitted to Geophys. Res. 
Lett. 1984. 
5. Ledley, B. G., T. L. Aggson, and R. C. Olsen, Radial electric field 
measurements near the midnight plasmapause, EOS, Transactions of the 
American Geophysical Union, ~, 256, 1984; presented to the Spring 
Meeting of the American Geophysical Union, Cincinnati, OH, May 14-18, 
1984. 
6. Olsen, R. C., T. L. Aggson, and B. Ledley, Observations of radial 
electric fields near the plasmapause, to be submitted to J. Geophys. 
Res., 1984 
7. Stone, N. H. and K. H. Wright, Jr., An interaction boundary about the 
space shuttle, to be·submitted to Geophys. Res. Lett., 1984. 
8. Horwitz, J. L., A simple formula relating the dusk sector radial 
electric field to electron energy dispersion at the inner edge of the 
plasma sheet, EOS, Transactions of the American Geophysical Union, ~ 
264, 1984; presented to the Spring Meeting of the American Geophysical 
Union, Cincinnati, OH, May 14-18, 1984. 
9. Horwitz, J. L. Relationship of dusk sector electric fields to electron 
energy dispersion at the inner edge of the plasma sheet for 
off-equatorially-mirroring electrons, submitted to J. Geophys. Res., 
1984. 
10. Horwitz, J. 
composition 
plasmasphere 
submitted to 
L., R. H. Comfort, and C.R. Chappell, Thermal ion 
measurements of the formation of the new outer 
and double plasmapause during storm recovery phase, 
Geophys. Res. Lett., 1984. 
11. Wright, K. H., N. H. Stone, U. Samir, Plasma expansion observed in 
laboratory wake experiments, to be presented to the 1984 International 
" 
10 
Conference on Plasma Physics, June 27-July 3, 1984, Lausanne, 
Switzerland. 
12. Wright, K. H., N. H. Stone, and U. Samir, The wake of the semi-infi-
nite plasma - the plasma expansion phenomenon, to be submitted to ~ 
Geophys. Res •• 
13. Samir, U., N. H. Stone, and K. H. Wright, Jr., The expansion of a 
rarefied space-plasma (e.g. ionosphere-magnetosphere) into a vacuum, 
to be presented to the XXI URSI General Assembly, August 28-September 
5, 1984, Florence, Italy. 
14. Olsen, C. R., D. L. Gallagher, C. R. Chappell, J.L. Green, and S. D. 
Shawhan, The hidden ion population - revisited, EOS, Transactions of 
the American Geophysical Union, ~, 256, 1984; presented to the Spring 
Meeting of the American Geophysical Union, Cincinnati, OH, May 14-18, 
1984. 
15. Decreau, R. M. E., C. R. Chappell, J. L. Green, J. H. Waite, Jr., D. 
Gurnett, R. H. Comfort, R. C. Olsen, and A. Pedersen, A 
three-dimensional view of the plasmaspheric bulge: GEOS-2/DE-1 
comparisons, EOS, Transactions of the American Geophysical Union, ~, 
256, 1984; presented to the Spring Meeting of the American Geophysical 
Union, Cincinnati, OH, May 14-18, 1984. 
16. Olsen, R. C., Recent results from the SCATHA satellite, to be 
presented to the XXI URSI General Assembly, August 28-September 5, 
1984, Florence, Italy. 
17. Green, J. L. and J. L. Horwitz, Fundamental nagnetospheric processes 
in the plasmapause region, EOS, Transactions of the American 
Geophysical Union, ~, 110, 1984-.--
18. Horwitz, J. L., Relationship of a dusk-sector electric field to 
electron energy dispersion at the inner plasma sheet, J. Geophy. Res., 
1984. 
19. Waite, Jr., J. H., J. L. Ho~,1itz, and R. H. Comfort, Diffusive 
equilibrium distributions of He in the plasmasphere, Planet. Space 
Sci., E, 611, 1984. 
20. Horwitz, J. L. and C. R. Chappell, Menu of DE 1 low energy plasma 
phenomena for Finnish collaboration, in Proceedings of the Second 
United States - Finnish Workshop on Magnetospheric and Ionospheric 
Phenomena in Auroral Regions, ed. by T. J. Rosenberg and J. Oksran, 
University of Maryland Press, pp. 69-77, 1984. 
21. Moore, R., J. L. Horwitz, and J. L. Green, Implications of solar flare 
dynamics for reconnection in magnetospheric substorms, Planet. Space 
Sci., in press, 1984. 
22. Horwitz, J. L., Residence time heating effects in auroral conic 
generation, Planet. Space Sci., in press, 1984. 
· '. 
-" 
11 
23. Horwitz, J. L., Dynamics of magnetospheric plasmas, to be published in 
AlAA book on spacecraft charging, ed. by A. L. Vampola, 1984. 
24. Nagai, T., J. H. Waite, Jr., J. L. Green, C. R. Chappell, R. C. Olsen, 
and R. H. Comfort, First measurements of supersonic polar wind in the 
polar magnetosphere, Geophys. Res. Letters, in press, 1984. 
25. Gallagher, D. L., Short wavelength electrostatic waves in the Earth's 
magnetosheath, submitted to J. Geophys. Res., 1984. 
26. Olsen, R. C. ,So D. Shawhan, D. L. Gallagher, J. L. Green, and C.R. 
Chappell, Observations of plasma heating at the Earth's magnetic 
equator, to be resubmitted to J. Geophys. Res., 1984. 
27. Horwitz, J. L. and J. L Green, Fundamental magnetospheric processes in 
the plasmapause region, to be submitted to Rev. Geophys. Space Phys., 
1984. 
· .~ 
Amount of Contract 
FINANCIAL DATA 
NAS8-33982 
Expenditures through May 31, 1984 
Balance Remaining 
End of Document 


Plasma and magnetospheric research

Analysis techniques and software development; data analysis and modeling; spacecraft sheath effects; laboratory plasma flow studies; and instrument development are described

Research developments in the following areas are discussed: (1) an ion trajectory computer code which plots the paths of ions ejected from the polar cusp ionosphere; (2) the response of plasmaspheric ion temperatures to geomagnetic activity; (3) spacecraft sheath effects; (4) plasma flow; (5) neutral gas temperatures; and (6) instrument fabrication, modification, and maintenance

QUARTERLY PROGRESS REPORT
Contract NAS8-33982
PLASMA AND MAGNETOSPHERIC RESEARCH
July-September 1985
by
Richard H. Comfort
and
James L. Horwitz
Prepared for
National Aeronautics and Space Administration
George C. Marshall Space Flight Center
Marshall Space Flight Center, Alabama 35812
{NASA-CB-176326) PJ.ASUA AND HAGHETOSPHEHIC N86-13.138
RESBABCfl Quarterly Progress Beport, Jul, ,-
Sep. , 1985 (Alabama Oniv,, Hcntsville.). 12 p
HC A02/HF A01 . CSCL .201 Unclas
G3/75 04740
Submitted by
The University of Alabama in Huntsville
School of Science
Huntsville. Alabama 35899
October 1985
https://ntrs.nasa.gov/search.jsp?R=19860003670 2020-03-20T15:59:44+00:00Z
ANALYSIS TECHNIQUES AND SOFTWARE DEVELOPMENT
Several programs and variations have been developed to determine statisti-
cal means of different plasma parameters when binned in different variables.
These parameters include temperatures, densities and spacecraft potentials for
any of the ion species, as well as ratios of these variables for any other ion
species to the corresponding variable for H . The variables for binning in-
clude L, radial distance, and geomagnetic latitude; and separate statistics are
automatically run for local morning and local evening data. These programs all
run from output files from the plasma parameter thin sheath analysis program.
A variant program also bins for magnetic activity, using either Kp or Dst,
which requires an additional magnetic activity input file. These programs can
be run either interactively or in batch mode, using a f i l e listing generated by
a "DIRECTORY" connmand. In addition to printed output, these programs generate
output files which can be used to plot the results. Programs to plot these
averaged data are under development.
DATA ANALYSIS AND MODELLING
Semi-empirical models of flux vs spin angle have been.established for the
RIMS Z heads, analogous to those for the radial head, by fitting the same
empirical model to the numerical results from parametric calculations with the
SHEATH program. Although the Z heads do not spin, these curves are needed to
specify the relationship between the flux at 90 degrees and that in the ram
direction. This w i l l later be used to try to improve the determination of
density from the Z head data.
Considerable progress has been made in the study of the ionosphere of
Uranus. A standard neutral atmosphere has been developed as the basis for
comparisons of the effects of electron precipitation, as well as new chemical
processes such as the influx of water or methane, on the upper atmosphere.
Eight separate cases for the ionosphere have been modelled, consisting of
different energies and flux levels for precipitating electrons. These auroral
simulations are being used to determine the dependence of the Lyman alpha
emissions on the energy flux of the precipitating electrons. This w i l l , in
turn, provide information on the energy deposition necessary in the Uranian
atmosphere to produce the observed levels of Lyman alpha emissions.
In the process of developing the standard neutral atmosphere, the
importance of vibrationally excited H3+ has been studied. This work includes
some recently determined reaction rates for reactions of excited H3+ with
neutrals. The effects of an influx of methane have been included in the most
recent versions of the neutral atmosphere. An influx of methane or perhaps
water is possible from the Uranian rings and could have significant impact on
the ionosphere.
In response to the referees' comments on the C++ paper (Ref. 1),
simulations have been performed to study the effect on the ion and electron
temperature of the strength and location of ion and electron heat sources in
the high altitude plasmasphere (L=3). These results suggest that while the high
altitude temperatures are highly sensitive to the magnitude of the source, the
spatial width (centered about the equatorial plane) is of minor importance in
determining the temperature structure along the f i e l d line. Additional
simulations of the 0-n- and N+ populations in the plamasphere have been
initiated to answer further comments by the referees on this paper.
SPACECRAFT SHEATH EFFECTS
The analysis of the charging event on ISEE-1 has been largely completed,
with the tentative conclusion that the fundamental cause was relatively low
conductivity on the solar arrays. Although the solar arrays were coated with
indium oxide to provide a conducting surface, it is apparent that the surface
characteristics of the ISEE-1 satellite were poorly determined, and varied
between ground tests. Charging studies of indium oxide coated surfaces show
that they can easily maintain differential potentials of many volts per meter,
and that they w i l l charge with respect to the ambient plasma when irradiated by
electron beams. These conclusions suggest that future scientific satellites,
with conductive coatings, should be treated in such a way as to insure (as much
as possible) that the level of conductivity is higher than that of ISEE-1 at
launch.
Analysis of electron gun operations on the SCATHA satellite shows evidence
for beam-plasma interactions, resulting in the heating of the ambient plasma
around the satellite. These results bear a strong resemblence to the SEPAC
operations on Spacelab 1. Preliminary results w i l l be presented to the Fal l
AGU meeting (Ref. 2)
Analysis of the spin modulation of the SCATHA satellite potential has been
completed. A manuscript (Ref. 3) has been prepared, reviewed by coauthors, and
revised in accordance with their comments; it should be submitted shortly.
An empirical relationship between the mean spacecraft potential and the
mean H density has been determined, using a variant of one of the statistical
programs discussed above. Based on data from about 60 plasmaspheric passes,
this relationship shows a monotonic decrease in spacecraft potential,
saturating at about -0.4 volt deep in the plasmasphere. The potential becomes
positive for densities below about 1000 cm" ; also, the standard deviation
increases substantially for these lower densities. This is probably associated
with both increased uncertainties in the analysis and effects of increasing
temperatures. Small, but significant, differences were found between results
from the morning and evening data sets. These may be effects of systematic
temperature differences, compositional differences, or a result of an
insufficient data sample.
LABORATORY PLASMA FLOW STUDIES
The Differential Ion Flux Probe (DIFP) for the Centaur I la payload has
been delivered to Southwest Research Institute fo integration. The functional
calibration, vibration, and post-vibration tests were completed in September,
Analysis of the laboratory calibration data w i l l take place during the next
reporting period. Launch of the Centaur I la w i l l take place in January 1986.
Fabricated parts for the dual ion source have been received from the
machine shop, and it is now being assembled. Testing w i l l begin in the next
reporting period.
INSTRUMENT DEVELOPMENT
The following tasks were carried out during this reporting period:
o Parts for a mass spectrometer were completed
o Fabrication of parts for a collimator were completed
o Parts were completed for the dual ion source
o Modifications and parts for the gimbal system of the vacuum tank were
completed
o Fabrication of parts for 5 detector heads is 90% complete
o A number of miscellaneous parts were manufactured and modifications
to instruments and systems were made.
PERSONNEL
We are pleased to have Dr. Roy Torbert join the UAH Physics Department
from the University of California at San Diego; he w i l l be carrying out
research under this contract.
PUBLICATIONS
In addition to the papers noted above, the following papers are at the
indicated stage of the publication cycle.
o Papers published during this reporting period:
those on ISEE-1 measurements of plasmapause structure (Ref. 4), the cleft
ion fountain (Ref. 5. 6). RIMS observations of molecular ions (Ref, 7). and the
geomagnetic mass spectrometer (Ref.8).
o Papers accepted for publication and in press are those on:
differential ion flux measurements on Spacelab 2 (Ref. 9). comparing
plasma disturbances caused by the space shuttle with those caused by small
ionospheric satellites (Ref. 10). DE-1 eclipse observations (Ref. 11).
supersonic outflows in the polar magnetosphere (Ref. 12), and solar wind
control of the geomagnetic mass spectrometer (Ref. 13).
o Papers submitted and in review are those on:
ions observed in the wake of DE 1 by RIMS (Ref. 14). ion acceleration
associated with plasma expansion into a vacuum (Ref. 15), the expansion of a
col Iisionless plasma into the wake of a moving body (Ref. 16). the
electrodynamic effects of the space shuttle on the environmental plasma from
OSS-1/STS-3 (Ref. 17). velocity filter mechanism producing bowl-shaped
distribution functions (Ref. 18), destiny of earthward streaming plasma sheet
boundary layer plasma (Ref. 19), plasma boundaries in the inner magnetosphere
(Ref. 20), equality of H and O* velocities (Ref. 21), transport of accelerated
ions in the polar magnetosphere (Ref. 22), SCATHA eclipse observations of
electric fields (Ref. 23), record charging events on ATS-6 (Ref. 24), RIMS
obsevations with the aperture bias (Ref. 25), PC 5 wave observations (Ref. 26),
and latitudinal distribution of plasma in the dusk bulge region (Ref. 27).
o Papers in preparation are those on:
equatorial ion observations (Ref. 28), ion velocities in the plasmasphere
(Ref. 29), and extensive comparisons between DE-1 and DE-2 observations of
plasmasphere-ionosphere coupling (Ref. 30).
In addition to those noted above the following papers have been or w i l l be
presented to national or international meetings.
o Paper presented was one on observations relating to the Coulomb excitation
mechanism for SAR arcs (Ref. 31).
o Abstracts have been submitted on:
the t a i l lobe ion mass spectrometer (Ref. 32), the destiny of earthward
streaming plasma (Ref. 33), ion bowl distribution (Ref. 34). the construction
of a three-dimensional electric potential model for high latitudes (Ref. 35),
and calculations of three-dimensional trajectories in the magnetosphere (Ref.
36).
, L
R. H. Comfort J. L.
REFERENCES
1. Chandler, M. 0., J. J. Ponthieu. T. E. Cravens, A. F. Nagy, and P. G.
Richards, Model calculations of minor ion populations in the plasmasphere,
submitted to JL. Qeoptiva^ . Res^ .. 1985.
2. Olsen, R. C. and H. A. Cohen, Electron beam experiments at high altitudes,
to be presented to the F a l l Meeting of the American Geophysical Union,
December 9-13, 1985, San Francisco, CA.
3. Craven, P. D. , R. C. Olsen, J. Fennel I, D, Croley, and T. Aggson,
Potential modulations on the SCATHA spacecraft, to be submitted to J^
Res-., 1985.
4. Nagai , T. , J. L. Horwitz, R. R. Anderson, and C. R. Chappell, Structure of
the plasmapause from ISEE-1 low-energy plasma and wave observations, J^
G£O_ptiy.S— RfiS-., 9J), 6622, 1985.
5. Lockwood, M. , M. 0. Chandler. J. L. Horwitz, J. H. Waite, Jr., T. E.
Moore, and C. R. Chappell, The cleft ion fountain, J*. Gao.pl>y_s^  Bas^ , 30.,
9736, 1985.
6. Horwitz, J. L. and M. Lockwood, The cleft ion fountain: a two-dimensional
kinetic model, J^ CeapJiys^  Bes^ , SQ. 9749, 1985.
7. Craven, P. D. , R. C. Olsen, C. R. Chappell, and L. Kakani , Observations of
molecular ions in the Earth's magnetosphere, J.^ GeopJiys.^  Bes^ , 2Q, 7599,
1985.
8. Lockwood, M. , T. E. Moore, J. H. Waite, Jr., C. R. Chappell. J. L.
Horwitz, and R. A. Heel is, The geomagnetic mass spectrometer — mass and
energy dispersions of ionospheric ion flows into the magnetosphere,
, 612. 1985.
9. Stone. N. H., B. J. Lewter. W. L. Chisolm. and K. H. Wright, An instrument
for differential ion flux vector measurements on Spacelab 2, in press.
Sci- I nstrum. , 1985.
10. Samir, U., N. H. Stone, and K. H. Wright, On plasma disturbances caused by
the motion of the space shuttle and small satellites — a comparison of in
situ observations, in press, J_ Gfiop&ys^  Res^ , 1985.
11. Olsen, R. C.. C. R. Chappell, D. L. Gallagher. J. L. Green, and D. A.
Gurnett, The hidden ion population -revisited, in press, J.^ GeopHys^
1985.
12. Horwitz, J. L., J. H. Waite, Jr., and T. E. Moore, Supersonic ion
outflows in the polar magnetosphere via the geomagnetic spectrometer, in
press. J— GfiopHy.^  Res^ , 1985.
13. Waite, Jr., J. H. . M. Lockwood, T. E. Moore, M. 0. Chandler, J. L.
Horwitz, and C. R. Chappelt. Solar wind control of the geomagnetic mass
spectrometer, in press, Proceedings of the Solar Wind-Magnetosphere
Coupling Conference, Pasadena, CA, Febrruary, 1985.
14. Samir, U., R. H. Comfort, C. R. Chappell, and N. H. Stone, The
distribution of low energy ions in the vicintiy of a magnetospher ic
satellite, submitted to iL. GfiojitLys-. Rea^ ., 1985.
15. Samir, U. , N. H. Stone, and K. H. Wright, Ion acceleration: a phenomenon
characteristic of the expansion of a plasma into a vacuum, submitted for
publication in the Monograph on Ion Acceleration in the Magnetosphere and
Ionosphere, Wellesley, MA. June 3-7, 1985.
16. Wright, K. H., D. E. Parks, I. Katz, N. H. Stone, and U. Samir, A note on
plasma expansion phenomena in wakes, submitted to J.^ Elasjna E&ys^ ., 1985.
17. Stone, N. H., K. H. Wright, K. Hwang, U. Samir, M. Murphy, and S. D.
Shawhan, Further observations of space shuttle plasma-electrodynamic
effects from OSS-1/STS-3, submitted to Gpnphys.Res. L£t±~, 1985.
18. Horwitz, J. L., Velocity-filter mechanism for ion bowl distributions,
submitted to iL. CeupJi^ s^  Bes.^ , 1985.
19. Green, J. L., and J. L. Horwitz, Destiny of earthward-streaming ions in
the magnetotail boundary layer, submitted to Geo-pDys^ Be^  Le-tt-., 1985.
20. Horwitz. J. L., S. Menteer, J. Turnley, C. R. Chappell. J. L. Burch, D.
Winningham, J. Craven, D. W. Slater. Plasma boundaries in the inner
magnetosphere, iL. Qfiophys-. B£S^ , SLQ, 1985.
21. Horwitz, J. L., and T. E. Moore, Comment on "A possible mechanism for
equal velocities of H* and 0+ in the distant magnetosphere" by Singh and
Schunk, submitted to J^. Geaptiys^  Bes^ ., 1985.
22. Horwitz, J. L., M. Lockwood. J. H. Waite. Jr., T. E. Moore, C. R.
Chappell, and M. 0. Chandler, Transport of accelerated low-energy ions in
the polar magnetosphere, submitted for publication in the Monograph on Ion
Acceleration in the Magnetosphere and Ionosphere, Wellesley, MA, June 3-7,
1985.
23. Olsen. R. C., T. L. Aggson, and B. G. Ledley, Observations of electric
fields near the plasmapause, submitted to iL. GecpJays^  fies-., 1985.
24. Olsen, R. C., The record charging events from ATS-6, submitted to
Spacecca£± BucJiels, 1985.
25. Olsen, R. C., C. R. Chappell, and J. L. Burch, Aperture plane potential
control for thermal ion measurements, submitted to J.^ Geapl)¥S.~ Bes^ . 1985.
26. Waite, Jr., J. H. , J. F. E. Johnson, C. R. Chappell, D. L. Gallagher, R.
C. Olsen, R. H. Comfort, D. Weimer, S. D. Shawhan, W. K. Peterson, and E.
G. Shelley, Plasma and wave observations of a PC 5 wave event, submitted
to J- Geflpiys^  Bes-., 1984.
10
27. Oecreau. P. M. E.. D. Carpenter, C. R. Chappell, R. H. Comfort. J. L.
Green. D. A. Gurnett. R. C. Olsen, and J. H. Waite, Jr., Latitudinal
plasma distribution in the dusk plasmaspheric bulge: r e f i l l i n g phase and
quasi-equi I ibrium state, submitted to xL. Gecpbys^  fias^, 1985.
28. Olsen, R. C., S. D. Shawhan, D. L. Gallagher, J. L. Green, C. R. Chappell
and R. R. Anderson, Plasma observations at the Earth's magnetic equator,
to be submitted to iL* G£aph¥S~ &£S~, 1985.
29. Chandler, M. 0., and C. R. Chappell, The flow of H and He along magnetic
f i e l d lines in the plasmasphere, to be submitted to vL. Geoptiys^  BJSS^ ,
1985.
30. Horwitz, J. L., L. H. Brace, R. H. Comfort, and C. R. Chappell, Dual
spacecraft measurements of plasmasphere-ionosphere coupling, to be
submitted to J^ . Qeoptiya^  &£S^ ., 1985.
31. Kozyra, J. u., T. E. Cravens, A. F. Nagy, D. W. Slater, R. H. Comfort, and
W, K. Peterson, An examination of the Coulomb collision excitation
mechanism for SAR arcs using Dynamics Explorer satellite data, presented
to the 5th Scientific Assembly of IAGA, Prague, Czechoslovakia, August 5-
17, 1985.
32. Horwitz, J. L., The t a i l lobe ion mass spectrometer , to be presented to the
Chapman Conference on Magnetotail Physics, Laurel, MD, October 28-31,
1985.
33. Green, J. L., and J. L. Horwitz, Destiny of earthward-streaming ions in
the magnetotail boundary layer, to be presented to the Chapman Conference
on Magnetotail Physics, Laurel, MD, October 28-31, 1985.
34. Horwitz, J. L., Ion bowl distributions, to be presented to the Fall
Meeting of the American Geophysical Union, December 9-13,1985, San
Francisco, CA.
35. Swinney, K. R., and J. L. Horwitz, A three-dimensional electric potential
model for high latitudes, to be presented to the F a l l Meeting of the
American Geophysical Union, December 9-13,1985, San Francisco, CA.
36. Reyes, T. R., and J. L. Horwitz, Three-dimensional ion trajectories in the
magnetosphere, to be presented to the F a l l Meet ing .of the American
Geophysical Union, December 9-13,1985, San Francisco, CA.
11
FINANCIAL DATA
NAS8-33982
AMOUNT OF CONTRACT $$1,254,999.00
Expenditures through September 1985 1,147,151.66
Balance September 30. 1985 107 847.34


Methods employed in the analysis of plasmas and the magnetosphere are examined. Computer programs which generate distribution functions are used in the analysis of charging phenomena and non maxwell plasmas in terms of density and average energy. An analytical model for spin curve analysis is presented. A program for the analysis of the differential ion flux probe on the space shuttle mission is complete. Satellite data analysis for ion heating, plasma flows in the polar cap, polar wind flow, and density and temperature profiles for several plasmasphere transits are included

QUARTERLY PROGRESS REPORT
Contract NAS8-33982
PLASMA AND MAGNETOSPHERIC RESEARCH
December 1983 - February 1984
by
Richard H. Comfort
and
James L. Horwitz
Prepared for
National Aeronautics and Space Administration
George C. Marshall Space Flight Center
Marshall Space Flight Center, Alabama 35812
Submitted by
The University of Alabama in Huntsville
School of Mathematical and Natural Sciences
Huntsville, Alabama 35899
March 1984
https://ntrs.nasa.gov/search.jsp?R=19840017137 2020-03-20T21:56:44+00:00Z
ANALYSIS TECHNIQUES AND SOFTWARE DEVELOPMENT
During this period, the program which converts DE/RIMS RPA data into
distribution functions' (RIMSDF) has been improved and extended. This
technique is desirable for analyzing charging phenomena, plasmas
characterized by multiple temperatures, and other non-Maxwellian plasmas.
By using the distribution function constructed from the measurements and
calculating the moments, it is possible to characterize such plasmas in
terms of a density and average energy. This method will be applied to the
warm, equatorially trapped plasmas frequently encountered by DE 1.
An instrumental artifact has been noted with this analysis technique.
For the ram direction the distribution function method provided plasma
parameters in agreement with those obtained by the thin sheath analysis of
the RPA curves from the radial head. This comparison was carried out in
the plasmasphere at a density of about 1000 cm 3, with temperatures of 0.4
to 0.5 eV. However, when end head data were analyzed, it appeared that
there was a colder population, as suggested by a sharp rise in the ion
distribution function below 1 eV. A fit to the 0-1 eV portion of the
distribution function indicated a temperature of M3.1 eV. Radial detector
data taken 90° from the ram direction showed a similar effect. This also
appears to correspond to the deviation of the thin sheath model from the
end head RPA data, noted in the previous report. Although it seems
plausible that this might be a sheath effect, analysis of eclipse data has
demonstrated that this phenomenon is independent of spacecraft potential.
This reduces the liklihood that this results from a sheath problem.
One interpretation of this phenomenon is that it results from an
increase in detector efficiency by about a factor of 5 for energies below 1
eV, due to stray electric fields within the entrance aperture region. An
empirical "fudge factor" has been developed and incorporated into the
distribution function analysis to remove this effect, until a clear
understanding of the problem can be used to develop an adequate
quantitative model to compensate for it.
Another area of significant development involves techniques for spin
curve analysis. Previously, Mike Chandler had generated a "catalog" of
spin curves from the SHEATH program for a broad range of values of Mach
number and spacecraft potential. By empirically testing a number of
mathematical models, we have determined one which represents the parametric
dependence of the spin curves on these two variables within 3% over the
range covered. This empirical, analytical model has been incorporated into
a computer subroutine, SPNMOD, for ready numerical evaluation of spin
modulated data. Another subroutine, TSP1N, has been developed which uses
TSHETH for normalization and SPNMOD for spin modulation. The TSPIN routine
has been incorporated into MSSPEC, the program which generates theoretical
spin curves for comparison with RIMS observed spin curves. This software
is now available for use in calibration and analysis studies and for the
further development of analysis techniques.
Development of methods for performing spin analysis on PWI Step
Frequency Receiver data is nearing completion. This effort is a vital link
in the identification of observed wave emissions. One of the first
applications will be to look for plasma noise generated in the DE 1 wake.
While developing this procedure, we also discovered a small error in
the interpretation of the spin phase angle of the RIMS data with respect to
the observed magnetic field. Since the error is of the order of one
degree, it is significant only to those RIMS studies which attempt to
obtain that order of angular resolution. One such study is that being
carried out by Mike Chandler, who is trying to resolve small field-aligned
flows of thermal ions in the plasmasphere.
We have continued to participate in efforts to obtain a Local Area
Network (LAN) for the Space Science Laboratory (SSL). Since that process
has been incorporated into the Class VI procurement, we have worked closely
with SSL personnel to produce wording in the Class VI RFP which will result
in the purchase of the best LAN for SSL. Dr. Gallagher is now serving as a
member of the SSL Computer Committee. Work has also started on the SCAN
workstation, most of the hardware and software having been received. All
these developments portend significant changes in the methods for carrying
out data analysis in SSL in the near future.
During this period, we completed installation at UAH of a computer
terminal which is connected to the SCAN central mode via a MSFC supplied
dedicated data line. This terminal is capable of displaying Tektronics
4010/4014 graphics and, with a compatible printer, could reproduce both
text and graphics. It will greatly facilitate the use of the SCAN central
node and the SSL Magnetosphere Branch PDF 11/34 computer by UAH researchers
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who must be at the University for other reasons.
A computer program to aid in the analysis of data acquired by the
Differential Ion Flux Probe (DIFP) on the STS-3 mission (March, 1982) has
>
been completed. This program generates a plot of the space shuttle
silhouette in any desired coordinate plane. For a given plane, several
vector projections and their variations over a one minute interval are
displayed: (1) the relative motion between the instrument and the shuttle;
(2) the instrument normal and tangent; (3) the plasma ram velocity; (4) and
the ambient magnetic field direction (the latter two assumed constant over
the interval). Use of these plots is essential in analyzing the observed
secondary (non-ram) ion streams. Preliminary indications are that these
secondary streams are correlated with the magnetic field direction and that
an interaction boundary may exist in front of the shuttle.
SATELLITE DATA ANALYSIS
Analysis of conical ion distributions between 1 and 10 thousand
kilometers altitude near the plasma sheet boundary has revealed 90 degree
pitch angle distributions and enhanced temperatures which are indications
of ion heating in the measurement region. DE/RIMS is apparently making the
first in situ measurements of ion acceleration in the topside ionosphere.
We find that hydrogen, helium, nitrogen, and singly and doubly charged
oxygen all participate in this process. Since pitch angle distributions
peaked at 90 degrees generally appear in only one mass species, it appears
that the heating of different ions occurs at different altitudes.
The study of high densities and plasma flows in the polar cap has made
considerable progress. HAPI observes 20 kms field-aligned flows and
transverse drifts of similar magnitude during a day 287, 1981 traversal of
the polar cap. Densities derived from PWI observations are found to be
about 50 cm"3. Both RIMS and HAPI also suggest high densities. RIMS
observations of low energy (<5eV) H and He indicate anti-sunward
convection at < 5 km s . These results will be presented to the Spring
AGU Meeting (Ref. 1).
Extensive effort was devoted to a detailed analysis of polar wind
observations on Day 287, 1981 for T. Nagai's study. The important
geophysical result was the first demonstration that an observed "classical"
polar wind flow was clearly supersonic. Much was also learned about
techniques for using aperture bias observations in conjunction with the
unbiased data, when this is possible. An interesting side result was the
determination that the data set analyzed had the characteristics of data
taken with an "open aperture" (90° half angle) RPA. This apparently
resulted from the integration over spin angle in assembling the data set or
because the distribution was sufficiently folded toward the field line that
all available flux entered the aperture. Future polar wind studies should
keep this latter possibility in mind in analyzing the data. This work has
been submitted for publication in GRL (Ref. 2).
Activity has also continued on Hunter Waite's PC-5 study. Detailed
quantitative analysis has been carried out to determine density,
temperature, and composition. Ambiguities associated with positive
spacecraft potentials have been difficult to resolve since other
conditions, not necessarily associated with the PC-5 event, appear to be
changing along the DE 1 orbit. The additional time taken for this
extensive analysis has also permitted a more thorough literature search,
which will result in an improved study. The paper documenting this study
is in a revised draft stage and will be submitted to JGR for publication in
the next reporting period (Ref. 3).
We have provided density and temperature profiles for several
plasmasphere transits to Larry Brace (GSFC) for comparison with his
Langmuir probe measurement on DE 2. These comparisons show a good
correlation between a topside ionosphere electron temperature enhancement
and the location (in invariant latitude) of the plasmapause density and
temperature gradients identified by RIMS. It appears that heating
processes causing the enhanced ion temperature gradient near the
plasmapause at high altitudes are also heating the electrons, followed by
thermal conduction down the field lines to the ionosphere. It remains to
be determined how prevalent this signature is.
LABORATORY PLASMA FLOW STUDIES
Data from the laboratory plasma flow interaction with a "semi-
infinite" plate experiment has been completed. The objective of the
experiment was to verify experimentally the existence of phenomena
occurring in the wake region associated with "plasma expansion into a
vacuum" theory. The characteristics of the data, specifically the
rarefaction wave, expansion front motion, ion velocity field, and ion
velocity behavior at the expansion from position, are all consistent with
the plasma expansion process. These results demonstrate the operation of
this process in the wake region of the plasma flow/body interaction.
Preliminary results were presented to the 1984 Yosemite meeting (Ref. 4),
and a draft of a paper containing detailed results is in preparation for
submission to JGR (Ref. 5).
PUBLICATIONS AND PRESENTATION
In addition to those noted above, the following papers are at the
indicated stage of the publication cycle.
Papers published were those on ionosphere-plasmasphere plasma
interchange (Ref. 6), multiple ion streams near the space shuttle (Ref. 7),
MHD model of whistler duct structure (Ref. 8) and four papers in the
proceedings of the Spacecraft/Plasma Interactions meeting (Ref. 9-12).
Papers accepted and in press include those on: electron energy dispersion
at the inner plasma sheet (Ref. 13), plasmaspheric He in diffusive
equilibrium (Ref. 14) and magnetospheric plasma dynamics (Ref. 15).
Submitted and under review are the paper on equatorial plasma heating (Ref.
16) and an article on the plasmapause conference (Ref. 17). The paper on
electrostatic waves in the magnetosphere (Ref. 18) has undergone such
extensive revision that it will be resubmitted. Abstracts for papers on
the following topics have also been submitted for presentation to the
Spring AGU Meeting: electron energy dispersion (Ref. 19), more hidden ions
(Ref. 20), radial electric field measurements (Ref. 21), and GEOS/DE1
comparisons of the bulge region (Ref. 22).
Jki
u
R. H. Comfort J. L. Horwitz -J
REFERENCES
1. Gallagher, D. L., J. D. Menietti, A. M. Persoon, J. H. Waite, Jr., and
C. R. Chappell, Evidence of high densities and ion outflows in the
polar cap during the recovery phase, to be presented to the Spring
Meeting of the American Geophysical Union, Cincinnati, OH, May 14-18,
1984.
2. Nagai, T., J. H. Waite, Jr., J. L. Green, C. R. Chappell, R. C. Olsen,
and R. H. Comfort, First measurements of supersonic polar wind in the
polar magnetosphere, submitted to Geophys. Res. Letters, 1984.
3. Waite, Jr., J. G., J. F. E. Johnson, C. R. Chappell, D. L. Gallagher,
R. C. Olsen, R. H. Comfort, D. Weimer, S. D. Shawhan, W. K. Peterson,
and E. G. Shelly, Observations of a PC-5 wave event on 1982 Day 195 by
particle and wave instruments on the DE 1 spacecraft, to be submitted
to J. Geophys. Res., 1984.
4. Stone, N. H., U. Samir, and K. H. Wright, The plasma expansion
phenomenon: Its characteristics, experimental observations and
possible application to the environmental dynamics of celestial
bodies, presented to the 1984 Yosemite Conference on the Planetary
Plasma Environment: A Comparative View, Yosemite, CA, January
28-February 3, 1984.
5. Wright, K. H., N. H. Stone, and U. Samir, The wake of the
semi-infinite plasma - the plasma expansion phenomenon, to be
submitted to J. Geophys. Res..
6. Horwitz, J. L., Major questions on the interchange of the thermal
plasmas between the ionosphere and the plasmasphere, J. Atmosph. Terr.
Phys., 45, 765, 1983.
10
7. Stone, N. H., U. Samir, K. H. Wright, Jr., D. L. Reasoner, and S. D.
Shawhan, Multiple ion streams in the near vicinity of the Space
shuttle, Geophys. Res. Lett., 10, 1215, 1983.
8. Wang, S., J. F. Wang, and R. H. Comfort, A magnetohydrodynamic model
of whistler duct structure in the magnetosphere, Planet Space Sci. ,
32_, 143, 1984.
9. Olsen, R. C., C. R. Chappell, D. L. Gallagher, J. L. Green, and S. D.
Shawhan, Potential control methods for thermal plasma measurements on
the DE-1 satellite, proceedings of the 17th ESLAB Symposium on
Spacecraft-plasma Interactions and their Influence on Field and
Particle Measurements, September 13-16, 1983, Noodwijk, Netherlands,
p. 177.
10. Olsen, R. C., P. M. E. Decreau, G. L. Wrenn, J. F. E. Johnson, A.
Pedersen, and K. Knott, A comparison of thermal plasma observations on
SCATHA and GEOS, proceedings of the 17th ESLAB Symposium on
Spacecraft-plasma Interactions and their Influence on Field and
Particle Measurements, September 13-16, 1983, Noodwijk, Netherlands,
p. 57.
11. Pedersen, A., C. R. Chappell, K. Knott, and R. C. Olsen, Methods for
keeping a conductive spacecraft near the plasma potential, proceedings
of the 17th ESLAB Symposium on Spacecraft-plasma Interactions and
their Influence on Field and Particle Measurements, September 13-16,
1983, Noodwijk, Netherlands, p. 185.
11
12. Whipple, E. C., R. C. Olsen, I. Krinsky, and R. Torbert, Anomalously
high potentials observed on ISEE-1 in sunlight, proceedings of the
17th ESLAB Symposium on Spacecraft-plasma Interactions and their
Influence on Field and Particle Measurements, September 13-16, 1983,
Noodwijk, Netherlands, p. 35.
13. Horwitz, J. L., Relationship of a dusk-sector electric field to
electron energy dispersion at the inner plasma sheet, in press, J.
Geophy. Res., 1984.
14. Waite, Jr., J. H. , J. L. Horwitz, and R. H. Comfort, Diffusive
equilibrium distributions of He in the plasmasphere, in press,
Planet. Space Sci., 1984.
15. Horwitz, J. L., Dynamics of magnetospheric plasmas, to be published in
AIAA book on spacecraft charging, ed. by A. L. Vampola, 1984.
16. Olsen, R. C., S. D. Shawhan, D. L. Gallagher, J. L. Green, and C. R.
Chappell, Observations of plasma heating at the Earth's magnetic
equator, submitted to J. Geophys. Res., 1983.
17. Horwitz, J. L. and J. L. Green, Fundamental magnetospheric processes
in the plasmapause region, submitted for publication in EOS,
Transactions of the American Geophysical Union, 1984.
18. Gallagher, D. L., Electrostatic waves in the Earth's magnetosheath, to
be resubmitted to J. Geophys. Res., 1984.
19. Horwitz, J. L., A simple formula relating the dusk sector radial
electric field to electron energy dispersion at the inner edge of the
plasma sheet, to be presented to the Spring Meeting of the American
Geophysical Union, Cincinnati, OH, May 14-18, 1984.
12
20. Olsen, C. R., D. L. Gallagher, C. R. Chappell, J. L. Green, and S. D.
Shawhan, The hidden ion population - revisited, to be presented to the
Spring Meeting of the American Geophysical Union, Cincinnati, OH, May
14-18, 1984.
21. Ledley, B. G., T. L. Aggson, and R. C. Olsen, Radial electric field
measurements near the midnight plasmapause, to be presented to the
Spring Meeting of the American Geophysical Union, Cincinnati, OH, May
14-18, 1984.
22. Decreau, R. M. E., C. R. Chappell, J. L. Green, J. H. Waite, Jr., D.
Gurnett, R. H. Comfort, R. C. Olsen, and A. Pedersen, A three-dimen-
sional view of the plasmaspheric bulge: GEOS-2/DE-1 comparisons, to
be presented to the Spring Meeting of the American Geophysical Union,
Cincinnati, OH, May 14-18, 1984.


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