Statistical properties of electromagnetic fluctuations in the scrape-off layer of the C-2W Field-Reversed Configuration

In the C-2W Field Reversed Configuration (FRC), initial comparisons of transport-relevant fluctuation properties in hydrogen and deuterium plasmas have been made. In addition to density fluctuation data probed by multi-channel Doppler Backscattering (DBS, in the toroidal wavenumber range $0.5 ≤ k_{/theta}/rho_{s} ≤ 5$), initial cross-polarization scattering (CPS) measurements of magnetic fluctuations have been made, indicating significant electromagnetic fluctuation components. These measurements target presently mainly the inner scrape-off-layer of the FRC plasma. Doppler Backscattering measurements show that statistical fluctuation properties such as the skewness of the density fluctuation amplitude probability distribution, and the prevalence of streamers with long-range radial correlations change significantly near the excluded flux radius. Via divertor bias voltage termination, the toroidal plasma rotation and radial $ extbf{ extit{E}} imes extbf{ extit{B}}$ velocity shear can be manipulated, allowing direct measurements of the fluctuation response. [1]. Radial transport barrier formation in both hydrogen and deuterium plasmas maintains a core plasma state characterized by very low ion-scale fluctuation levels [1] in agreement with global gyrokinetic simulations [2].