Radiation control in Tritium and Deuterium-Tritium JET baseline plasmas – part II

In ITER and next step fusion reactors, the chosen materials for the first wall are Beryllium and Tungsten because of their good thermodynamic and mechanical properties, low level of erosion, neutron activation, and Tritium retention. However, radiation events due to the release of such high Z materials, can be responsible of plasma cooling, which can affect the ELM dynamics [A.R. Field et al. 2021 Plasma Phys. Control. Fusion 63 095,013], trigger MHD instabilities [G. Pucella et al. 2021 Nucl. Fusion 61 046,020], and inhibit the achievement of thermonuclear temperatures. For these reasons, over the years, methods to control the radiation level have been developed and integrated in the scenario design development. JET is the ideal testbed experiment to conduct radiation control studies being equipped with an ITER-like wall and able to operate with Tritium and Deuterium-Tritium fuel mixtures in plasmas with input power up to 33 MW. In this work, radiation control in JET ITER-like wall baseline plasmas during Tritium and Deuterium-Tritium baseline operations is reported, complimenting the work presented in [L. Piron et al. Radiation Control in Deuterium, Tritium and Deuterium-Tritium JET baseline plasmas – part I]. The behavior of radiation control methods has been investigated statistically. Such analysis suggests that, in Tritium hollow density profiles develop because of the high density level achieved at the plasma edge. This turns out to affect the ELM dynamics, exacerbating the radiation control. A possible solution to counter radiation build up is proposed and consists in exploiting the presence of error field correction coils to mitigate the ELM dynamics, and to induce density pump-out, thus affecting the density profile evolution.