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
ANALYSIS TECHNIQUES AND SOFTWARE DEVELOPMENT

Several programs and variations have been developed to determine statistical 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 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 file s 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 fil e listin g 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 wil 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 will , 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 highl y 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 fiel 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 wil 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 wil 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 wil l take place during the next

reporting period. Launch of the Centaur I la wil 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 wil 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 wil 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 filte r 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 field s (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 wil 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 tai 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 Fal 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 flu x 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: refillin 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

fiel 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 tai 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 Fal l

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 Fal 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 Fal 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