Line shapes in hot fusion plasma can refelct the existence of velocity shear in the plasma. High resolution spectroscopy is needed to differentiate between line broadening by this effect and thermal line broadening. We used this technique to study plasma rotation on the RTP tokamak and the T2R reversed field pinch. Line shifts of hydrogen revealed atom speeds of 40 km/s resp. 20 km/s. Observations of the C IV resonance lines on RTP showed a relation between changes in velocity shear and the deposition of electron cyclotron heating with respect to the location of electron thermal transport barriers as well as a poloidal roation of several km/s.
F. G. Meijer, F. G. Meijer,
"Line shapes and plasma movements in hot fusion plasmas", Proc. SPIE 5258, IV Workshop on Atomic and Molecular Physics, (17 November 2003); doi: 10.1117/12.544331; https://doi.org/10.1117/12.544331