Experimental Study of the Maxwell Stress in Electromagnetic Collisional Drift Turbulence

We present experimental results for magnetic field fluctuations observed in an Argon plasma column produced in Controlled Shear Decorrelation Experiment (CSDX), operated with a helicon waves source. The observed magnetic fluctuations have power spectra, spatial distributions, and parametric variations that are similar to the potential and density fluctuations, which have been previously shown to be collisional drift waves. The magnitude of the normalized magnetic field fluctuations is much smaller than the normalized density and potential fluctuations, and is roughly consistent with theoretical expectations. These results suggest that the observed magnetic fluctuations are small magnetic components of these essentially electrostatic drift waves, and are not drift Alfven waves. The Maxwell stress has been calculated from the cross-spectrum of the B˜r and B˜ theta components, and is much smaller than that of the Reynolds stress observed previously in CSDX, indicating that the Maxwell stress does not significantly influence the formation of the shear layer which is driven by the Reynolds stress in CSDX.