Low-frequency microinstabilities in the PLT tokamak

Abstract

A turbulence with wavelengths in the range 2–0.2 cm and with a spectrum in the range of frequencies of drift waves has been observed in the PLT discharge with scattering of microwaves. The total density fluctuation was ñe/n̄e≃5×10−3–10−2. It is estimated that this turbulence can cause an anomalous transport much larger than that predicted by neoclassical theory. As the PLT discharge developed a central minimum of the electron temperature, an increase in the turbulence level was observed with a very strong poloidal localization on the outside of the plasma torus.