IFS Seminar

Abstract: 

Thermal waves, as they are termed, are not actually waves

but they act and behave similar to a ‘standard wave’ more precisely

they are diffusive-type oscillations with propagation characteristics.

Over the past few decades thermal waves have been used extensively

to study the optical, thermal and electronic properties of solids, liquids 

and gases. This is mainly accomplished using a device known

as a driven thermal wave resonator cavity (TWRC) where frequency

and cavity length scanning are used to measure the thermal and other

properties. In this talk I will illustrate how these concepts can be carried 

over to the plasma medium. Thermal waves are produced using

sinusoidally time-varying heat sources and can be generated in 

magnetized plasmas through  external wave sources, such as electron 

cyclotron heating or through oscillatory electron beams, as is the case in 

the experiments I will describe that were carried out using the Large 

Plasma Device (LAPD) at UCLA. Using this technique and mapping out 

the thermal wave field, we were able to obtain precise measurements of

the thermal conductivity in the magnetized plasma. The mathematical 

properties of thermal waves are also interesting and I will describe

some of the progress in modeling thermal waves in inhomogeneous 

plasmas, making use of field theory concepts.