Electromagnetic Turbulence In Increased Beta Plasmas In The Large Plasma Device

The variation of pressure-gradient-driven turbulence with plasma beta (up to beta approximate to 15%) is investigated in linear, magnetized plasma. The magnitude of magnetic fluctuations is observed to increase substantially with increasing beta. More importantly, parallel magnetic fluctuations are observed to dominate at higher beta values, with delta B-parallel to/delta B-perpendicular to approximate to 2 and delta B/B-0 approximate to 1%. Parallel magnetic fluctuations are strongly correlated with density fluctuations and the two are observed to be out of phase. The relative magnitude of and cross-phase between density and parallel magnetic field fluctuations are consistent with the dynamic pressure balance (P + B-0(2)/2 mu(0) = constant). A local slab model theory for electromagnetic, modified drift Alfven waves, including parallel magnetic fluctuations, shows partial agreement with experimental observations.