Manuscript Information Authors

[1]	Amr Hasheim Bekheit, Plasma & Nuclear Fusion Department, Nuclear Research Center, Atomic Energy Authority, Cairo, Egypt.

Abstract

Most of the analysis of Edge Transport Barriers (ETB) in small size divertor tokamak so far concentrated on the regime with dominant ion heating, i.e with (T_i ＞ T_e). As rector conditions are characterized by dominant electron heating, and consequently (T_i  T_e). The Edge Transport Barrier in the regime with dominant electron heating, (T_i  T_e) can be simulated by using B2SOLPS5.0 2D multifluid transport code. The results of simulation demonstrated the following: (1) In a small size divetor tokamak in regime with dominant electron heating, (T_i  T_e) have a strong effect on plasma density. (2) Regime dominant with electron heating, (T_i  T_e) has a strong influence on Ion Edge Transport Barriers (IETB). (3) The depth of the radial electric field well in the regime with dominant by electron heating, (T_i  T_e) is greater than the depth of the radial electric field in the regime dominated by coupling electron and ion heating (T_e = T_i). Within this framework, deeper ‘E_r’ wells provide stronger radial field shear, which increased the capacity for turbulence suppression, leading to improved plasma confinement. Also the depth of the radial electric field is a function of electron temperature. (4) A direct comparison of the pressure characteristic scale length ‘L_P’ and stability parameter ‘_e’ shows very little change in response to regime dominant with electron heating, (T_i  T_e). This provides additional evidence for strong edge pressure profiles in ‘ETB’ and there appears to be significant ‘_e’ constraint. Due to the coupling of characteristic lengths of electron temperature and plasma density via ‘_e’ = 0.006_{Ti  Te}, the profile inside ‘ETB’ can be specified by the limit on ‘L^P’. (5) Lowing the plasma line density results in an elevated the stability parameter ‘_e’ and effectively shifting of plasma density outboard.

Keywords

Pressure Length, ETB, E_r Well

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