Doppler model for adiabatic toroidal compressor driftwave frequency profiles

Microwave and CO₂ laser scattering experiments on the ATC adiabatic toroidal compressor tokamak have shown that there exists a spectrum of fluctuations with frequencies l f l ≲ 1 MHz at wavelengths λ ∼ 0.28 cm and with l f l ≲ 400 kHz for λ ∼ 1 cm. However, a typical maximum frequency calculated for given experimental density and temperature profiles is f ≲ 150 kHz for the longer wavelengths and differs from the experimental results by roughly a factor of 2 or 3. At shorter wavelengths the calculated maximum f≲ 100 kHz, which differs quite substantially from the experimental result. This discrepancy is interpreted as evidence of an E × B Doppler shift from a radial electric field.