Overview:

Professor Gilchrist specializes in plasma electrodynamic sensors and technological applications principally for in-space applications. His research efforts span in-space plasma measurements, ground-based chamber simulations of high-speed space plasma flows principally to investigate current collection and sheath physics, and the development of advanced space electric propulsion applications. He is Co-PI for the development of the nanoparticle Field Extraction Thruster (nanoFET) concept that was selected by the NASA Institute for Advanced Concepts (NIAC) for Phase 2 level development. He is in the forefront of efforts to develop space tether technology for scientific and technological applications including electrodynamic tethers as a new propellantless space propulsion technology. He was a Co-I on the NASA MSFC ProSEDS electrodynamic tether experiment providing plasma diagnostics and high-voltage tether control instrumentation. Also, Professor Gilchrist led a team of over 100 students to develop Michigan’s first-ever student satellite (called Icarus) for NASA and is co-faculty lead for a new student space experiment called TSATT (Tethered SATellite Testbed). He has led the development of an advanced microwave interferometer for highly accurate plasma density and turbulence measurements of space electric propulsion plasma thrusters and designed a successful neutral gas release system for spacecraft charge neutralization. He was PI for the Shuttle Electrodynamic Tether System (SETS) experiment that flew on the STS-75 shuttle mission in 1996 as part of the Tethered Satellite System (TSS) mission. He was 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., Prof. Gilchrist 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, plasma electrodynamics, radiowave link design, systems design, and design of spacecraft systems. He has been a faculty advisor for Michigan’s student Solar Car Race Team and the Student Space Systems Fabrication Laboratory (S3FL). He has well over 100 refereed and conference publications.

Details:

Professor Gilchrist is a Co-PI in the development of the Nanoparticle Field Emission Thruster (nanoFET). Using highly accelerated nanoparticles it is possible to create a paradigm shift in electric space propulsion technology. The nanoFET concept uses microelectromechanical (MEMS) structures to transport, charge, extract, and electrostatically accelerate nanoparticles for propulsive thrust in new ways that can substantially improve performance and mission capabilities. The nanoFET recently was selected by NASA’s Institute for Advanced Concepts (NIAC) for further development. Highly accelerated nanoparticles is also be explored for biomedical and material processing applications.

As a Co-I for NASA’s ProSEDS electrodynamic tether propulsion mission, developed is to fly on a Delta-II in 2003, Professor Gilchrist was 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 was responsible for providing a high-voltage tether current control and monitoring instrument. Of special interest, was that Professor Gilchrist also lead a group of University of Michigan students (over 100) to build a small, independent instrumented satellite for the ProSEDS mission to be placed at the end of its tether to provide enhanced tether dynamics data to NASA.

He was 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 advanced microwave and millimeter wave interferometers 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. He was also Co-I on a follow-on AFOSR program to develop a high power to develop a high power Hall thruster. He and his students were responsible for developing 17, 35, and 70 GHz interferometers which are being used to investigate small scale plasma structure near the primary ionization and acceleration zones of EP thrusters.

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 possible flight as part of a NASA funded program called STEDI (STudent Explorer Demonstration Initiative).

He was 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.