Improved energy confinement with neon injection in the DIII-D tokamak

In this paper the authors will report the first direct measurements of the fully stripped neon 10+ density profile in a plasma with enhanced energy confinement due to neon injection. This is made with a calibrated charge exchange recombination (CER) system. It is found that the neon 10+ density is peaked like the electron density with a slightly higher concentration towards the edge. The good news is that the neon 10+ fraction is less than 1% (normalized to the electron density). The radial electric field can also be computed from the CER measurements on DIII-D. The shear in the E x B velocity is found to exceed the maximum growth rate of the ion temperature gradient (ITG) mode over part of the profile, a condition for the suppression of turbulent transport. This agrees with the reduced power balance thermal diffusivities near the magnetic axis