Ion temperature measurements in tokamak plasmas by Rutherford scattering
A Rutherford scattering diagnostic has been applied at the TEXTOR tokamak to obtain spatially and temporally resolved information on the temperature of the bulk ions in the plasma. A helium atomic beam passes vertically through the plasma core. A small part of the injected atoms is scattered elastically by the thermally moving plasma ions. The ion temperature in the scattering volume can be determined from the broadening of the energy spectrum of the scattered particles. Energy analysis of the scattered atoms is performed by a mass-selective time of flight analyser detecting the particles at an observation angle which is selectable between 3 and 8 . Coincidence techniques have been applied successfully in this detector for rejection of background events triggered by detections of neutrons and gamma radiation. Ion temperature profiles were measured on a shot-to-shot basis by shifting the cross-section of the diagnostic beam and the observational volume of the analyser through the plasma. The ion temperatures measured in ohmic deuterium plasmas were found to be in reasonable agreement with those obtained from passive neutral particle analysis. Deuteron density profiles could be deduced from the scattering yield measured at different radial positions in the plasma. Although theoretical predictions showed that the majority of the probing helium atoms lose one electron during the elastic scattering process on multiply charged carbon and oxygen ions, contributions from impurities to the observed experimental spectrum appear dominant for impure plasmas.
Bibliographic Reference: Article: Review of Scientific Instruments, Vol. 63 (1992) No. 6, pp. 3359-3368
Record Number: 199211267 / Last updated on: 1994-11-29
Original language: en
Available languages: en