Churchill, R.M.Lipschultz, B.Theiler, C.2017-09-302017-09-302017-09-30201310.1088/0029-5515/53/12/122002https://infoscience.epfl.ch/handle/20.500.14299/140904Measurements are presented of the boron (B5+) density in the pedestal region at the low-field side (LFS) midplane and the high-field side (HFS) midplane of Alcator C-Mod. In H-mode plasmas, a large (>=10x) in–out asymmetry in impurity density forms, with larger densities at the HFS. In contrast, there is no impurity density asymmetry in L-mode or I-mode plasmas. A comparison of pedestal parameters in H-mode plasmas shows that the HFS impurity density pedestal width and position remain fairly fixed over a range of plasma conditions, while the LFS pedestal width widens, and the pedestal position shifts in towards the core as the plasma current is lowered, indicating a change in the underlying transport.text::journal::journal article::research article