Stimulated excitation of thermal diffusion waves in a magnetized plasma pressure filament*

Results are presented from basic heat transport experiments using a magnetized electron temperature filament that behaves as a thermal resonator. The experiments were carried out in the Large Plasma Device (LAPD) at the Basic Plasma Science Facility (BaPSF), University of California, Los Angeles. Using a small cathode source, low energy electrons are injected along the magnetic field into the afterglow of a pre-existing plasma forming a hot electron filament embedded in a colder plasma. A series of low amplitude, sinusoidal perturbations are added to the cathode discharge bias that create an oscillating heat source capable of driving large amplitude electron temperature oscillations. Langmuir probes are used measure the amplitude and phase of the thermal wave field over a wide range of driver frequencies. The results are used to verify the excitation of thermal waves, confirm the presence of thermal resonances, and demonstrate the diagnostic potential of thermal waves through measurement of the parallel  and cross-field thermal diffusivity.