POLOIDAL ASYMMETRY AND GRADIENT DRIVE IN-CORE ELECTRON-DENSITY AND TEMPERATURE-FLUCTUATIONS ON THE TEXAS EXPERIMENTAL TOKAMAK-UPGRADE

Electron temperature and density fluctuations are measured in the core of the Texas Experimental Tokamak-Upgrade (TEXT-U) [P. H. Edmonds, E. R. Solano, and A. J. Wootton, in Proceedings of the 15th Symposium on Fusion Technology, Utrecht (Elsevier Science, Amsterdam, 1989), Vol. 1, p. 342] plasma across the poloidal cross section. The high spatial resolution of the heavy-ion beam probe (HIBP) and correlation radiomet ry of electron cyclotron emission (CRECE) reveal that both the density and temperature fluctuations are strongly poloidally asymmetric. Temp erature fluctuation measurements indicate a broadband drift wave featu re localized near the plasma equatorial plane on both the high- and lo w-field sides, which is consistent with density fluctuation measuremen ts by far infrared (FIR) scattering. In contrast, the HIBP observes th is feature localized only to the low-field side. Excellent spatial res olution allows us to investigate whether changes in the gradient affec t the fluctuation amplitudes. We find that indeed, the temperature flu ctuations increase with the electron temperature gradient. Results als o link density fluctuations to changes in the density gradient. (C) 19 96 American Institute of Physics.