Integrated modelling of the ramp-up phase of the hybrid scenario for the JT-60SA tokamak

JT-60SA is a large superconducting tokamak built and operated by Europe and Japan under the Broader Approach Satellite Tokamak Program. The machine is designed to support the exploitation of ITER and the investigation of key physics and engineering issues for future demonstration power plants. The main operational parameters of the plasma scenarios, envisaged for the Integrated Research Phase and described in the JT-60SA Research Plan [1], were simulated using the 0.5-dimensional code METIS and the 2-dimensional equilibrium code ACCOME, as reported in [2]. Moreover, the feasibility of the flat-top phase of these scenarios was confirmed by means of 1.5-dimensional transport codes [3, 4]. However, it is of primary importance to simulate the ramp-up in order to assess whether the main plasma parameters foreseen for the scenario are achievable and under which range of assumptions. The goal of this study is to model the ramp-up phase of the scenario 4-2 (hybrid) (3.5 MA/2.28 T, q95=4.4, βN =3.0) with the JINTRAC [5] suite of codes and the Bohm/gyro-Bohm [6] semi-empirical transport model, taking as starting point the modelling performed with the METIS code. We are predicting the current density, ion density, ion temperature and electron temperature, self-consistently with the plasma equilibrium. The speed of the current ramp-up is imposed, while a feedback loop acting on the gas puff rate is controlling the density in order to follow the target volume averaged density. The heating power deposition profiles and current densities of ECRH and NBI are modelled with the GRAY [7] and PENCIL [8] codes respectively, injecting the power of 37 MW (7 MW of ECRH and 30 MW of NBI). The results of the modelling in terms of plasma kinetic profiles evolution, L-H transition, flux consumption and neutral beam shine-through are presented for different levels of ECRH power and different NBI switching on times. JINTRAC results are fairly close to the ones predicted by METIS, however the L-H transition, predicted by Martin scaling, is found earlier in JINTRAC. The electron temperature profiles are also very sensitive to the different shape of the ECRH power deposition computed by GRAY, with respect to the Gaussian-like profiles imposed by METIS. References [1] JT-60SA Research Plan, version 4.0 www.jt60sa.org/pdfs/JT-60SA_Res_Plan.pdf (September 2018) [2] G. Giruzzi et al 2020 Plasma Phys. Control. Fusion 62 014009 [3] L. Garzotti et al 2018 Nucl. Fusion 58 026029 [4] J. Garcia et al 2014 Nucl. Fusion 54 093010 [5] Romanelli M. et al 2014 Plasma and Fusion Research 9 3403023 [6] M Erba et al 1997 Plasma Phys. Control. Fusion 39 261 [7] D. Farina, Fusion Science and Technology 154, 52 (2007) [8] C.D. Challis et al 1989 Nucl. Fusion 29 56