Past Work:

 1.      We developed a technique for identifying magnetospheric
 particles that have travelled between pairs of spacecraft in
 the magnetosphere.  The difference in the particle energy at
 the two spacecraft then gives the magnetospheric electrostatic
 potential difference between the two locations.  This enables the
 mapping of potentials by different spacecraft to be tied together
 so that a global map of potentials can be constructed.  This work
 has been published in the Journal of Geophysical Research, Vol.
 103, No. A1, Pages 93-102, Jan. 1, 1998.  See "Publications".

  2.      We extended this technique to obtain the magnetospheric
 potential distribution along a spacecraft path by identifying
 particle paths that intercept the spacecraft path at two different
 times.  From this the component of the electric field along the
 particle path can be obtained.  Thus electric field information
 can be obtained from particle data.  This work has been published in
 Geophysical Research Letters, Vol. 26, No. 11, Pages 1561-1564,
 June 1, 1999.  See "Publications".

Present Work:
 

 1.      We have applied this technique to data from the German
 Equator-S spacecraft, using data from the ESIC (Equator-S Ion
 Composition) instrument.  We were able to obtain the electric
 field and the potential distribution along the spacecraft path
 from the ESIC ion data, and have compared this electric field with
 that obtained from the EDI (Electric Drift Instrument) on
 Equator-S.  A paper describing this work is under preparation.

 2.      Dr. Elden Whipple presented an invited paper at the Cluster II
 Workshop which was held in London, September 22-24, 1999.  The
 title of the paper was "On the Possibility of Identifying and
 Using Magnetospheric Particles that Travel between the Cluster
 Spacecraft".  This paper has been written and will be published
 in the Proceedings of the Workshop.  See "Publications".

Future Work:
 

 1.      We plan to begin work on extending some previous results on
 the acceleration of particles in magnetospheric current sheets,
 such as those which occur at the magnetopause and in the magnetotail.
 The previous work developed drift equations for charged particles
 in thin current sheets where it was previously thought that
 adiabatic theory should not apply.  We have shown that it is
 possible to use so-called "generalized adiabatic theory" to obtain
 particle acceleration in such regions.  This would have a direct
 application to the "reconnection" process, which is still poorly
 understood.  We plan to apply these theoretical results, once
 they have been developed, to plasma data obtained by the Hydra
 instrument on the Polar spacecraft.

 2.      We plan to continue our work on the identification and use of
 charged particles that travel between pairs of spacecraft.  A
 number of participants in the London Cluster II Workshop expressed
 interest in becoming familiar with this technique.  We will work
 with Cluster investigators to acquaint them with the technique
 which we have developed and help work out applications to the set
 of four Cluster spacecraft.

Publications:
 

 1.      "Identification of magnetospheric particles that travel
 between spacecraft and their use to help obtain magnetospheric
 potential distributions", J. Geophys. Res., Vol. 103, No. A1,
 Pages 93-102, Jan. 1, 1998.

 Pdf  (700 K)

 2.      "Magnetospheric electric fields from ion data", Geophys. Res.
 Lett., Vol, 26, No. 11, Pages 1561-1564, June 1, 1999.

 Postscript  (11.6 M)
 Pdf  (338 K)

 3.      "On the possibility of identifying and using magnetospheric
 particles that travel between the Cluster spacecraft", to be
 published in the Proceedings of the Cluster II Workshop, London,
 September 22-24, 1999.

 Postscript  (4.3 M)
 Pdf  (457 K)

Other Links:

• HYDRA Homepage
• (U,B,K) information
• University of Washington's Space Physics

Contact Information:
 

Prof. Elden Whipple:

Affiliate Professor at University of Washington
Geophysics Program
P. O. Box 351650
Seattle, WA 98195-1650

whipple@geophys.washington.edu
353 Johnson Hall
Phone:(206) 616-5796

Undergraduate Student at University of Washington
danstarr@u.washington.edu

Phyisics Graduate Student at U.C., Berkeley
jazzman@socrates.berkeley.edu

Last modified: 10/01/99.    Web page questions & comments may be directed to: Dan Starr