Statistical study of particle flux footprint widths with tungsten divertor in EAST

Abstract

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Study of power width scaling in scrape-off layer with 2D electrostatic turbulence code based on EAST L-mode discharges

“…8, it is evaluated at the inner divertor and the in-out asymmetry of the SOL power width in EAST is significant. 10 The predictions by the HD model are evaluated by Eq. (1) in Ref.…”

“…A number of experimental studies have been carried out in the last twenty years to scale k q . [1][2][3][4][5][6][7][8][9][10] Some of the most prominent work in this area is done by Eich et al 2,4 They proposed a multimachine (Eich) scaling law of k q based on the multimachine databases, which predicts that k q,ITER % 1 mm for the ITER baseline inductive H-mode scenario. 4 The Eich scaling of k q shows a strong negative dependence on the poloidal magnetic field at the OMP separatrix B p , given by k q ¼ 0:63B À1:19 p , and is independent of the major radius.…”

“…9 In EAST, k q scalings also exhibit the same dependence on B p , but with about two times larger (the same) amplitudes at the outer (inner) divertor. 5,6,8,10 The reason for the larger amplitude at the outer divertor is probably due to the lower hybrid wave (LHW) heating scheme. 8,11 Even though the scaling dependence on B p is robust, recent studies indicate that there is another important scaling parameter that is not included in the Eich scaling, i.e., the edge electron temperature T e,edge .…”

“…8,11 Even though the scaling dependence on B p is robust, recent studies indicate that there is another important scaling parameter that is not included in the Eich scaling, i.e., the edge electron temperature T e,edge . 7,10 In ASDEX-Upgrade (AUG) L-mode plasmas, k q scaling yields k q / W MHD =n e;edge À Á À0:93 / T À0:93 e;edge for stiff pressure profiles, where n e,edge is the edge electron density. 7 In EAST H-mode plasmas, the scaling of particle flux fall-off width k js at the inner divertor is k js / W MHD = n e ð Þ À0:5 / T À0:5 e;edge for stiff pressure profiles, where n e is the line-averaged electron density.…”

“…7 In EAST H-mode plasmas, the scaling of particle flux fall-off width k js at the inner divertor is k js / W MHD = n e ð Þ À0:5 / T À0:5 e;edge for stiff pressure profiles, where n e is the line-averaged electron density. 10 According to Refs. 5 and 6, the ratio of k js to k q is a constant (%1.3) for measurement by the divertor Langmuir probes.…”