Carbon and nitrogen impurity transport coefficients are determined from gas
puff experiments carried out during repeat L-mode discharges on the Mega-Amp
Spherical Tokamak (MAST) and compared against a previous analysis of helium
impurity transport on MAST. The impurity density profiles are measured on the
low-field side of the plasma, therefore this paper focuses on light impurities
where the impact of poloidal asymmetries on impurity transport is predicted to
be negligible. A weak screening of carbon and nitrogen is found in the plasma
core, whereas the helium density profile is peaked over the entire plasma
radius.Comment: 17 pages, 7 figure
