Measurements of low-energy neutral hydrogen efflux during ICRF heating

Using the Low Energy Neutral Atom Spectrometer, measurements were made of the H o and D o 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 10 15 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.