Drift Wave Chaos and Turbulence in a LAPTAG Plasma Physics experiment

Whenever there is a pressure gradient in a magnetized plasma drift waves occur spontaneously. Drift waves have density and electrical potential fluctuations but no self magnetic field. In our experiment the drift waves form spontaneously in a narrow plasma column. ($n_{e} =5X10^{11}cm^{3},\mbox{\, }T_{e} =3eV,B=200Gauss,\mbox{\, d}ia=\mbox{\, 5\, cm,\, L=\, 1.5\, m})$. As the drift waves grow from noise simple averaging techniques cannot be used to map them out in space and time. The ion saturation current $I_{sat} \propto n\sqrt{T_{e}}$ is recorded for an ensemble of 50 shots on a fixed probe located on the density gradient and for a movable probe. The probe signals are not sinusoidal and are filtered to calculate the cross-spectral function CSF $ = \int {\sum\limits_{nshot} Ifix_{,\omega } (\vec{{r}}_{1} } ,t)I_{mov,\omega} \left( {\vec{{r}}_{1} + \Delta \vec{{r}},t+\tau } \right)dt$, which can be used to extract the temporal and spatially varying wave patterns. The dominant wave at 18 kHz is a rotating spiral with m$=$2. LAPTAG is a university-high school alliance outreach program, which has been in existence for over 20 years. Work done at the BaPSF and supported by NSF/DOE.