Ion temperature measurements in tokamak plasmas by Rutherford scattering

For understanding the behaviour of thermonuclear plasmas, diagnostics play an indispensable role. The ion temperature is a crucial quantity, but rather difficult to measure. A technique to measure the ion temperature is the Rutherford scattering method, which is the subject of this thesis.Energetic light atoms, injected as a diagnostic beam into the plasma, are elastically scattered by the thermally moving plasma ions. The broadening of the energy spectrum of the atoms, scattered through small angles, is a direct measure for the temperature of the ions. This thesis describes the development of the Rutherford scattering diagnostic and its application at the medium-sized TEXTOR tokamak. Up to now, ion temperatures have been measured throughout the complete plasma discharge with an accuracy of 8 percent and a time and space resolution of 100 ms and 0.05 m, respectively at a scattering angle of 7 deg. Deuteron density profiles could be deduced from the scattering yield measured at different radial positions in the plasma. The ratio of hydrogenic isotopes, hydrogen and deuterium, was determined from the separate contributions in the spectrum of helium particles scattered on hydrogen and deuterium. (author). 115 refs.; 59 figs.; 8 tabs