Paper

Effect of Scrape-Off-Layer Current on Reconstructed Tokamak Equilibrium

Kruger, S E, Hebert, J D, Hanson, J D, King, J R, Held, E D, Jepson, J R, Groebner, R J

2017

Overview

Methods are described that extend fields from reconstructed equilibria to include scrape-off-layer current through extrapolated parametrized and experimental fits. The extrapolation includes both the effects of the toroidal-field and pressure gradients which produce scrape-off-layer current after recomputation of the Grad-Shafranov solution. To quantify the degree that inclusion of scrape-off-layer current modifies the equilibrium, the \\(\\chi\\)-squared goodness-of-fit parameter is calculated for cases with and without scrape-off-layer current. The change in \\(\\chi\\)-squared is found to be minor when scrape-off-layer current is included however flux surfaces are shifted by up to 3 cm. The impact on edge modes of these scrape-off-layer modifications is also found to be small and the importance of these methods to nonlinear computation is discussed.

• Publisher: Cornell University Library, arXiv.org
• Subject: Equilibrium methods / Goodness of fit / Parameter modification / Pressure gradients / Tokamak devices