Plasma Physics : Kinetic Theory and MHD

My doctoral degree in Physics was obtained at University of Maryland at College Park. The thesis was in the field of Plasma Physics, and was written under the supervision of Dr. Fred Skiff (who is now at the University of Iowa). While in graduate school, I was supported mainly through departmental Teaching Assistantships, and a Research Assistantship paid through National Science Foundation (NSF) grants.

When temperatures are extremely high, such as in the interior of stars, atoms and molecules can be ionized into electrons and ions/radicals. The positively and negatively charged particles make up the plasma, and they interact with each other thru electric and magnetic forces. My dissertation involved studying the perturbations in the ion distribution functions, when low frequency waves are launched in a plasma. The research involved the use of tunable lasers to measure the distribution functions.

Above is a plot of a Perturbed Ion Distributions in a plasma. One sees the typical wave structure propagating along the spatial direction, while the velocity axis shows the sloshing back and forth of the ions due to the wave.

Based on the data, we have been able to determine the 3D wave vector and wave potentials, made the first observations of wave-particle resonances in velocity space (a comparison is that of a surfer harnessing the energy of waves) and observed kinetic (or ballistic) modes in velocity space. Contrary to what earlier theoretical work suggested, we found that some of the kinetic modes did not damp very strongly, and instead propagated quite a distance through the plasma. You can read our preprint to Physics of Plasmas, to learn more about these new kinetic waves that we have been studying. There is still a lot more work to be done in this field.

When I have time to do so, I also run a 3d MHD code for Dr. Adil Hassam of UMCP, to study stabilisation of a tokomak plasma using velocity shear. So far we are fairly certain that the shear, and an elongated cross section for the plasma, does help stabilise the plasma - but we still have one or two questions to answer (and the code takes ages to run .....). Click here here to see some computer simulations of a tokomak plasma that started out laminar, went unstable, and then has been partly stabilized by using velocity shear.

Studies such as the above two are all tied into developing fusion energy as a viable alternative for mankind.