Research
Professional 
RESEARCH EXPERIENCE
Professor Gilchrist specializes in plasma electrodynamics and the development of associated sensor systems with emphasis to space plasmas and applications. He is in the forefront of efforts to develop space tether technology for scientific and technological applications which include exploration of the ionosphere/thermosphere as well as developing electrodynamic tethers for propulsion applications. He has led the development of an advanced microwave interferometer for highly accurate plasma density and turbulence measurements of space electric propulsion plasma plumes and designed a successful neutral gas release system for spacecraft charge neutralization. He is Principal Investigator for the Shuttle Electrodynamic Tether System (SETS) experiment which flew on the STS-75 shuttle mission in 1996 as part of the Tethered Satellite System (TSS) mission. He is a Co-I on the NASA MSFC ProSEDS electrodynamic tether experiment selected for flight in August, 2000. He is a Co-I on an Air Force program to developed a high powered Hall electric propulsion thruster and was a Co-PI on another program investigating spacecraft electromagnetic interaction effects of advanced electric propulsion systems. He is also PI for an Air Force effort to investigate fundamental issues associated with propagating artificially generated relativistic electron beams in space. Prior to receiving his Ph.D., he held industry R&D and management positions over a twelve year period developing numerous microwave components and sub-systems including the first integrated microwave sampler for aerospace applications. His instructional emphasis is in the areas of electromagnetics, radiowave propagation, plasma electrodynamics, and design of spacecraft systems.
As a Co-I for NASA's ProSEDS electrodynamic tether propulsion mission which is to fly on a Delta-II in August, 2000, Professor Gilchrist is responsible for providing both plasma diagnostics and high-voltage control instrumentation. This includes a Langmuir probe and spacecraft potential monitor designed to rapidly operate in a variable plasma environment. In addition, he is responsible for providing high-voltage tether current flow control and monitoring interface instrument. Of special interest, is that Professor Gilchrist is a leading a group of over 60 University of Michigan students to build a small instrumented satellite to be placed at the end of the ProSEDS tether to provide enhanced tether dynamics data to NASA and its commercial partners on ProSEDS.
As Principal Investigator for the SETS experiment on the 1996 TSS shuttle mission (STS-75), he lead a team of researchers from the University of Michigan, Utah State University, and Stanford University in the investigation of tether electrodynamic fundamentals in the Earth's ionosphere and the use of space tethers for scientific and technological applications. The SETS team specifically addressed questions pertaining to system level current-voltage characteristics and ionospheric effects as well as the use of tethers as long baseline double probes to measure natural electric fields, as long receiving antennas, as a method to enable simultaneous multipoint in-situ ionospheric measurements, as a remote electrical reference for spacecraft charging studies, and the study of electromagnetic pulse propagation along a conductor in a magnetized plasma. The TSS-1R experimental results, which the SETS team helped generate, have been pivotal in establishing the ability to drive high currents through the ionosphere for power generation and propulsion applications. Professor Gilchrist made specific contributions in identifying mechanisms for the highest tether currents generated during the mission.
Professor Gilchrist was Co-PI for an AFOSR program to make fundamental plasma electromagnetic measurements to support the development and integration of closed-drift, hall-effect electric thrusters for next generation spacecraft. This included establishing quantitative measures of amplitude and phase distortion to electromagnetic signals propagating through plasma plumes. He has led the development of an advanced microwave interferometer for highly accurate plasma density measurements for electric propulsion diagnostics. In addition, techniques using Ion Acoustic Wave (IAW) propagation in a moving plasma to establish ion temperature and drift velocity has been developed by his students. Now, he is Co-I on a follow-on AFOSR is Co-I on an AFOSR program to develop a high power to develop a high power Hall thruster. He is responsible for developing a 35 GHz interferometer which is being used to investigate small scale plasma structure near the primary ionization zone of the thruster.
He was PI for a NASA funded study of space tether application to ionospheric/thermospheric research and was organizer for a 1994 international workshop on the subject with over 50 participants from five countries. The unique ability to use space tethers for simultaneous, multipoint measurements was of special interest to the participants. Professor Gilchrist, in 1994, also led a team of University of Michigan students, engineers, and collaborating organizations (NASA Marshall Space Flight Center, Lockheed-Martin Corporation (Denver), Tether Applications Incorporated, University of Texas (Dallas), University of Alabama (Huntsville), and NASA Goddard Space Flight Center) in proposing a space tether mission to the lower thermosphere/ionosphere called AIRSATT (Atmospheric-Ionospheric Research Satellite using Advanced Tether Technology). The AIRSATT mission was selected by the University Space Research Association as one of six (out of sixty-six) proposals for an in-depth Phase 1 study for eventual flight as part of a NASA funded program called STEDI (STudent Explorer Demonstration Initiative).
He is also PI for an Air Force program to investigate theoretical issues of propagating artificially generated relativistic electron beams in space. This effort has generated quantitative models describing beam propagation, the scattering by the atmosphere, and the importance of the Earth's magnetic field in confining beam spread. He was responsible for early relativistic particle models used in describing ionization effects in the mesosphere and supported the initial assessment of relativistic electron beam induced modifications to atmospheric electric fields.
Professor Gilchrist was a Co-Investigator on the 1992 high energy electron beam CHARGE-2B tethered rocket experiment with responsibility for the science design of its neutral gas payload charge-neutralization experiment. He participated in both the VCAP Experiment on the Spacelab-2 Shuttle mission and the CHARGE-2 tethered rocket experiment which was a conducting tether experiment testing some of the TSS concepts.
His doctoral research at Stanford University was divided into two primary areas: a) investigations of electrodynamic effects due to electron beam and neutral gas emissions into a space plasma; and, b) radar and theoretical investigations of energetic electron beam generated artificial plasma density structures in the ionosphere using rockets and spacecraft. His masters thesis research, sponsored in part by a General Electric Fellowship, at the University of Illinois involved implementing an ionospheric total electron content radio measurement experiment optimized for nighttime application in the E and lower F regions of the ionosphere. The experiment was based on Faraday rotation, using a ground based HF transmitter, rocket borne receiver, and digital signal processing to extract the desired signals.
Professor Gilchrist has also held both technical and supervisory positions in industry (Watkins-Johnson Company) over a twelve year period associated with microwave integrated circuit and subsystem design for radar and ecm applications. Research activities included: phased array radar, low-noise amplifiers, phase-shifters, and microwave sample-and-hold circuits.
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PROFESSIONAL EXPERIENCE CHRONOLOGY
1991-Present:
Professor (Associate, 5/1997-5/2003; Assistant, 9/1991-5/1997) at The University of Michigan in Electrical Engineering and Computer Science (Radiation Laboratory) and the Atmospheric, Oceanic and Space Sciences Department (Space Physics Research Laboratory). Responsibilities include undergraduate and graduate education and research. His instructional emphasis is in the areas of electromagnetics, plasma electrodynamics, systems design, and spacecraft design.
1989-1994:
Deputy Investigator (since 1991) and Program Manager (since 1990) for SETS. Responsibilities included: a) development and coordination of mission planning inputs to achieve SETS/TSS-1 science goals; b) science experiment design; c) overall management of SETS contractual responsibilities including flight hardware and mission support operations; and d) all decisions reflecting SETS relations with NASA and other TSS-1 teams. (1989-1990: Deputy Program Manager SETS)
1984-1991:
Graduate Research Assistant- Research was divided into three areas: a) investigations of electrodynamic effects due to electron beam and neutral gas emissions into a space plasma; b) radar and theoretical investigations of energetic electron beam generated artificial plasma density structures in the ionosphere using rockets and spacecraft including modeling of relativistic electron beam penetration into the atmosphere; and c) development of functional objectives to meet SETS science requirements for TSS-1 mission and their coordination with mission personnel. Advisor: Professor Peter M. Banks
1978-1990:
Watkins-Johnson Company- Held both technical and supervisory positions associated with microwave integrated circuit and subsystem design for radar and ecm applications. Research activities included: phased array radar, low-noise amplifiers, phase-shifters, and microwave sample-and-hold circuits.
1977-1978:
Graduate Research Assistant in the University of Illinois Aeronomy Laboratory Rocket Program- Implemented a nighttime ionospheric electron density measurement experiment based on Faraday rotation, using a ground based HF transmitter and a rocket borne receiver. Advisor: Professor Leslie G. Smith