Research Interests

Plasma Physics

It is estimated that more than 99% of the known matter in the universe is in the  plasma state. Consequently, it is not surprising that plasma physics has  become an area of intense research activity and has developed into an  important, well-defined branch of physics. Much of the current research  in plasma physics is directed toward the solution of problems relating to  controlled thermonuclear fusion. Control of the hydrogen bomb fusion  reaction involves heating and containing a plasma with thermal energies  in the 100 million degree range. Other important applications of plasma  physics which continue to suggest research problems include the areas of  ionospheric and magnetospheric physics, astrophysics, solid state plasma  physics, gaseous electronics, MHD energy conversion, ion propulsion, and  laser development.

 Current research by Professor Willett and co-workers involves solution of Maxwell's equations for the electric  and magnetic fields in conjunction with either kinetic or fluid equations  which describe the dynamics of the particles in a plasma or relativistic  electron beam. The kinetic approach employs the Vlasov equation for the  distribution function of each species of charged particle. The fluid  approach employs continuity, momentum transfer, and state equations  either for each species of particles or for the plasma considered as a  single continuous medium. The most recent projects relate to controlled  fusion and free-electron lasers.

"Free Electron Laser with Longitudinal Wiggler and Finite Magnetic Field in a Partially Filled Waveguide", H. Mehdian, J.E. Willett, B. Maraghechi, and Y. Aktas, Phys. Plasmas 3, 1130 (1996).

"Beam SpaceCharge Modes in a FreeElectron Laser", J.E. Willett, Y. Aktas, and B. Bolon, Phys. Plasmas 3, 2441 (1996).

"Response to Comment on FreeElectron Laser with Longitudinal Wiggler and Finite Magnetic Field in a Partially Filled Waveguide", J.E. Willett, Phys. Plasmas 3, 3866 (1996).

"Electrostatic Beam Modes in a FreeElectron Laser with a Coaxial Wiggler", J.E. Willett, U.H. Hwang, Y. Aktas, and H. Mehdian, Phys. Rev. E 57, 2262 (1998).

"SpaceCharge Waves in a Coaxial Plasma Waveguide", U.H. Hwang, J.E. Willett, and H. Mehdian, Phys. Plasmas 5, 273, (1998).

"SpaceCharge Waves in the Wiggler Field of a Raman FreeElectron Laser, J.E. Willett, B. Bolon, Y. Aktas, and H. Mehdian, Phys. Rev. E 57, 7169 (1998).

"Effects of Wiggler and Axial Guide Fields on Wave Propagation in a FreeElectron Laser", H. Mehdian, J.E. Willett, and Y. Aktas, Phys. Plasmas 5, November (1998).