Experiments on the ATC Tokamak

A study of electron density fluctuations in the ATC is presented, using both microwave and CO2 laser scattering. Fluctuations are observed with wavelength between 2 cm and 0.3 mm and with frequencies up to 1.5 MHz. Their amplitude is of the order of 0.01. Local measurements of the safety factor q and effective Z are also reported. The value of q was obtained from the shifts of injected ion orbits relative to the magnetic surfaces; effective Z was obtained from the scattering rate of radially localized injected ions. Both these measurements indicate a peaking of effective Z on axis. Finally, measurements of the parallel and anti-parallel fast neutral spectra are presented which indicate very different profiles for the parallel and antiparallel ion temperature.