Measurements of low-energy neutral hydrogen efflux during ICRF heating

Using the Low Energy Neutral Atom Spectrometer, measurements were made of the Ho and Do efflux from PLT during ion cyclotron heating experiments. The application of RF power at frequencies appropriate to fundamental and second-harmonic heating results in a rapid, toroidally uniform rise in the charge-exchange efflux at a rate of about 1015 cm−2 · s−1 · MW−1. This flux increase is larger at lower plasma currents. The cause of this flux and its impact on plasma behaviour are discussed.