Estimation of the scrape-off-layer width in tokamak using the electron balance equations

Abstract

The width of the scrape-off-layer has been a critical issue in the design of fusion reactors. This width has been derived using Braginskii electron energy balance and electron momentum balance equations. The most significant influence on the edge plasma profiles, especially on the divertor heat flux, was the drift element. Therefore, the drift mechanisms are used to find the width of scrape-off-layer. The derivation of these formulas with some presumptions leads to the width of scrape-off-layer ∼ qρci, where q is a safety factor, and ρci is an ion Larmor radius. The plasma parameters for the small-size divertor tokamak are solved using the B2SOLPS5.02D code at different locations. Then, they are applied in the scrape-off-layer width relation to correlate the width with these variables. In these locations, the scrape-off-layer width was found to be uneven. The results show that the diffusion coefficient, heat flux density, impurities, and the creation of edge transport barriers significantly affect scrape-off-layer width.