Results of an experiment relating apparent Doppler ion temperatures with non-thermal velocities in hot-fusion plasmas
We present the results of an experiment carried out in the core of a hot magnetically confined plasma to substantiate a claimed relationship between apparent ion temperatures and non-thermal velocities. For this, the heaviest ions were injected into the plasma by laser ablation and localised ion temperatures were obtained from Doppler line-widths and energy spectra of escaped charge-exchange neutrals. Strong collisional coupling between majority (H+) and impurity ions ensures that these should be well thermalised. However, the linear dependence found between apparent ion temperature and mass (H, O, Si, Fe) permits one to relate apparent Doppler ion temperatures to non-thermal velocities. The implications for the physics and diagnosis of thermonuclear plasmas are addressed.