Small-Scale Density Fluctuations in the Adiabatic Toroidal Compressor

A new class of density fluctuations has been observed in the adiabatic toroidal compressor (ATC) tokamak by spectral analysis of scattered microwaves. The observed frequency spectrum is consistent with that of drift waves with amplitudes that are maximum in the wavelength range 0.5-1.0 cm where the transverse inertia of ions is important for plasma stability. The total density fluctuation is ${\tilde{n}}_e\gtrsim 5\times {10}^{-3\mathrm{}}{\overline{n}}_e$. We estimate that these fluctuations could account for a large fraction of the electron energy losses of the ATC discharge.