In-out impurity density asymmetry in the pedestal region of Alcator C-Mod

TY - JOUR

T1 - In-out impurity density asymmetry in the pedestal region of Alcator C-Mod

AU - Churchill, R. M.

AU - Lipschultz, B.

AU - Theiler, C.

PY - 2013/12/1

Y1 - 2013/12/1

N2 - Measurements 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.

AB - Measurements 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.

UR - http://www.scopus.com/inward/record.url?scp=84889038020&partnerID=8YFLogxK

U2 - 10.1088/0029-5515/53/12/122002

DO - 10.1088/0029-5515/53/12/122002

M3 - Article

AN - SCOPUS:84889038020

SN - 0029-5515

VL - 53

JO - Nuclear Fusion

JF - Nuclear Fusion

IS - 12

M1 - 122002

ER -