L-mode plasmas analyses and current ramp-up predictions for a JT-60SA hybrid scenario

Abstract

In this work, L-mode analyses are performed in order to assess a modeling framework for the prediction of electron cyclotron resonant heating (ECRH) -assisted current ramp-up phases for JT-60SA tokamak hybrid scenario #4-2. We compare two turbulence transport models, CDBM and TGLF, using the integrated modeling code CRONOS. Model validation is performed on the basis of an L-mode ramp-up phase in a JET plasma, and a flat-top L-mode TCV (Tokamak a configuration variable) plasma with applied ECRH. Parameter scans in and in-edge electron temperature (T e ) are performed. Our results indicate effective prediction of the q profile in JET ramp-up if edge T e is properly captured. Indeed, our sensitivity scan demonstrates the strong impact of edge T e on q profile evolution. The results of CDBM and TGLF modeling show good agreement with the experimental measurements. With respect to a JT-60SA hybrid scenario, a significant amount of ECRH off-axis is required to maintain a q profile above unity across the entire plasma radius. Based on an analysis of power deposition location, we find that ECRH applied close to ρ = 0.33 allows a compromise between a q profile larger than unity, and high central T e . We evaluate two current ramp-up rates, where the fast rate is double that of the slower rate. The quantity of ECRH required for the fast ramp scenario is found to be greater by almost a factor of two than that required in the slow ramp scenario.