Estimation of SOL/Divertor Plasma Heating by Electron Cyclotron Radiation from Core Plasma in ITER

摘要

1. Introduction. Coupling of the plasma located1 inside the separatrix (the core plasma) with that-outside (SOL and divertor plasma) is usually taken into account via an exchange of boundary conditions (at the separatrix) between the transport codes for respective parts of plasma. In ITER tokamak, this pertains to the Automated System for Transport Analyses(ASTRA) [1] and the SOLPS4.3 [2] code. Since the mean free path(m.f.p.) of neutral atoms in ITER plasma is rather short and the intensity of the electron cyclotron (EC) waves with m.f.p. comparable with the minor radius of the plasma column is high [3]-[5], the EC radiation emitted by the core plasma could contribute to nonlocal coupling of the core and the SOL+divertor plasmas. Recent calculations [6] of the local electron energy balance for parameters needed for the steady-state operation of ITER [7] were based on a self-consistent model employing ID transport and 2D equilibrium models (1.5D approximation). That modeling included calculation of the electron cyclotron radiation (ECR) power density profile using the CYNEQ code [4],[6],[8] incorporated into the ASTRA framework. However, modeling, [6] did not allow for the absorption of the EC waves in the SOL+divertor region, despite the total power of EC radiation (on the top of the ECRH/ECCD power) in the vacuum vessel can amount, in the regime [7], to as much as -30 MW.