Ion heating and orbit losses in Ni experiments on Wendelstein VII-A

The ion temperature of 1 keV as measured by energy analysis of cx neutrals has been confirmed by measurements of the Doppler broadening of the 0 VIII line both perpendicular and parallel to B, and the neutron flux from thermal D-D reactions. To fulfill the overall energy balance the necessary confinement of the fast particles has to be improved by a radial electric field which is built up by lost particles. Lost particles have been detected by the laser induced fluorescence of the sputtered Fe atoms. The stationary hydrogen spectrum has found to agree with the calculation assuming collisional slowing down of the injected particles. The measured neutron flux depends on the collisional slowing down time as expected. The transient response of the neutron flux and the cx particle flux at switching off the deuterium injector have been measured. Low harmonics of the ion cyclotron frequency have been observed by probe measurements