College of Liberal Arts & Sciences

# Math Physics Seminar

**Abstract:**

Hot plasmas have a large number of degrees of freedom.

Generally in physics, a fundamental way to explore the degrees of freedom is through scattering. In plasma physics it is traditional to describe waves using fluid theory where the plasma degrees of freedom consist of a few collective modes with discrete dispersion relations w(k). However, experiments on wave scattering, for example on the ion acoustic wave, produce inconsistent results in the fluid model.

Theoretically, even with the simplifications of a 1-D, low-frequency, electrostatic model where the electrons are treated as a neutralizing fluid, Vlasov-ion plasma actually supports an uncountable infinity of

modes: the Case-Van-Kampen continuum. In weakly-collisional plasma, I am not sure what the degrees of freedom are theoretically. In this talk I will describe my efforts to develop a scattering theory for collective excitations in hot (Vlasov) and weakly-collisional plasma.

It is a work in progress.