Experimental Plasma Physics
(949) 824-4253 email: mcw@uci.edu
My laboratory webpage has an extensive overview of my research activities.
Professor McWilliams earned his Ph.D. in 1980 from Princeton University and the B.A. from the University of California, Irvine in 1975. Prior to finishing his Ph.D. he joined the faculty at UCI. His teaching has been recognized with multiple awards for Outstanding Contributions to Undergraduate Education at UCI. He was the inaugural winner of the UC systemwide Presidential Faculty Award for Excellence in Undergraduate Research recognizing his leadership in creating and overseeing undergraduate research opportunities. He is founding director of the Campuswide Honors Program and founder of the Undergraduate Research Opportunities Program.
Plasma physics, the study of matter in the ionized state, is undergoing revolutionary synthesis of theory and experiment. In a general sense, plasma physics is developing most in nonlinear dynamics. Experimentalists seek unprecedented phase-space and turbulence diagnostics, higher spatial and spectral resolution of laboratory and astrophysical measurements, and delineation of particle and energy transport mechanisms. Synthesis of theory and experiment come on a number of fronts, partially responding to empirical advances; large scale computing allows three dimensional, nonlinear models which simulate plasma configurations in laboratory and space. Theoretical, computational, and experimental results allow a coherent picture of plasma physics phenomena to unfold.
Among the most challenging problems for plasma physicists is the understanding of transport properties of plasmas, especially in turbulent regimes. The basic processes of diffusion, for example, have yet to be understood. The transport of particles and energy is an exciting area of plasma research at UCI.
Wave energy transport is understood partially in the linear regime, yet nature is inherently nonlinear in its dynamics. In the laboratories at UCI there is now a sophisticated experimental diagnostic base for addressing transport questions. We have made progress in understanding ion diffusion in quiet or turbulent plasmas, measuring both spatial diffusion and velocity space transport. Measurements have been compared to Fokker-Planck predictions with success.
Experiments study ion diffusion and convection in turbulent plasmas via laser induced fluorescence diagnostics. Wave propagation measurements help to identify the electric field structures responsible for the transport. Experiments with flaring magnetic fields have allowed the study of unusual distribution functions formed by ions interacting with radio frequency waves and the diverging field, phenomena observed momentarily by satellites in the Earth's magnetosphere.
The development of new research tools is important in the plasma laboratory since new tools allow new scientific pursuits. Presently, we are helping develop a new class of diode lasers for laser induced fluorescence diagnostics.
All of this research is done with the close collaboration of graduate and undergraduate students with research physicists and faculty. A primary reason for performing the research at UCI is to train students. Placing students in forefront research efforts is the best training available, allowing considerable one-on-one teaching on topics of interest not only to the student and professor but also to other leading researchers in physics.
Representative Publications
Direct Measurement of Velocity Space Transport in a Plasma, (with J. Bowles and N. Rynn) Phys. Plasmas 1, 3814 (1994).
Transverse Ion Acceleration and Ion Conic Formation in a Divergent-Field Laboratory Plasma, (with M. Zintl and N. Wolf) Phys. Plasmas 2, 4432 (1995).
Single Beam Laser Induced Fluorescence Technique for Plasma Transport Measurements, (with D.A. Edrich and N.S. Wolf) Rev. Sci. Instrum. 67, 2812 (1996).