Heat Transport in Interacting Magnetized Electron Temperature Filaments

Results are presented from basic heat transport experiments and numerical simulations of multiple magnetized electron temperature filaments in close proximity. This arrangement samples cross-field transport from nonlinear drift-Alfven waves and large scale convective cells. Experiments are performed in the Large Plasma Device (LAPD) at UCLA. The setup consists of three biased CeB$_{\mathrm{6}}$ crystal cathodes that inject low energy electrons (below ionization energy) along a strong magnetic field into a pre-existing large and cold plasma forming 3 electron temperature filaments embedded in a colder plasma, and far from the machine walls. A triangular spatial pattern is chosen for the thermal sources and multiple axial and transverse probe measurements allow for determination of the cross-field mode patterns and axial filament length. We have characterized the spontaneous thermal waves and drift-Alfven waves that develop on an individual filament when a single source is activated. When the 3 sources are activated, and in close proximity, a complex wave pattern emerges due to interference of the various wave modes leading to enhanced cross-field transport and chaotic mixing. Steep thermal gradients develop in a periphery region of the filaments where higher azimuthal wavenumber drift-Alfven modes are excited. Detailed spectral analysis and comparison with nonlinear fluid and gyrokinetic simulations will be reported.