Magnetospheric physics, space plasma physics.
My main research interest is in magnetospheric physics, with specific emphasis on the sources, transport, and acceleration of magnetospheric particle populations. This includes the design, fabrication, and testing of state-of-the-art instrumentation for spacecraft and the analysis of the data collected by these instruments. Our group's particular specialty is measuring the composition of ions in space plasmas and using the composition measurement both as a tool for distinguishing the sources of the ions and for differentiating between different acceleration and transport mechanisms.
I have been involved in building instruments and analyzing the data for a number of missions. Most recently, I am starting to look at data from the CLUSTER mission, a joint U.S.-European mission, which involves four spacecraft flying in close formation in order to study plasma processes on small scales and to distinguish spatial from temporal changes in the plasma properties. The satellites were put successfully into orbit by two launches in July and August, 2000. Our group provided an ion composition instrument which uses time-of-flight techniques to measure the distribution functions of the plasma in space.
I am the lead investigator for a similar instrument on the German Equator-S satellite. Results from this data set include a better understanding of ion transport from the ionosphere to the equatorial magnetosphere and into the inner magnetosphere, and evidence for stable, long-term magnetic reconnection at the earth's magnetopause. A similar instrument is on-board the FAST (Fast Auroral SnapshoT) spacecraft. FAST flies in a polar orbit, taking data over the aurora in order to study ion acceleration in the auroral region. A recent study using this data set showed the importance of charge exchange as a loss process by comparing how the relative fluxes of different ion species change with radial distance.
A somewhat different type of instrument was built for the Advanced Composition Explorer (ACE), a spacecraft that orbits at the L1 Lagrangian point between the earth and the sun and monitor solar particles and cosmic rays. Our instrument, SEPICA, uses a combination of electrostatic deflection, a multi-wire proportional counter, and a solid state detector to measure particles from solar flares and particles accelerated in interplanetary space.
I believe graduate students should be exposed to all aspects of a spacecraft project: the design, building, and testing of the flight hardware; developing the software necessary to handle the large quantities of data; and the final data analysis. Although the time scales of spacecraft projects can be too long for a student to be involved in all phases on one project, we have enough ongoing projects that a student can be involved in the hardware stage on one project but do his/her final thesis work using the data from another project.
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