The Fusion Group has been working hard to improve our understanding of the deuterium-tritium (D-T) plasmas carried out at JET during late 2021. These experiments broke the world fusion energy record and are providing us with invaluable physical insight in preparation of ITER’s experiments.
Our research has culminated in two recent papers published at Plasma Physics and Controlled Fusion. One tackles the optimization of the H and 3He minority heating schemes for D-T, while the other describes a recent upgrade we developed for the calculation of the diffusion operator. A brief overview is given together with their links to the journal version as follows.
1. Prediction of ICRF minority heating schemes for JET DT experiments
Achieving high performance discharges has been one of the main goals of JET in preparation for the D-T campaign. A number of physical mechanisms have been under investigation during previous campaigns, especially plasma heating.
This paper focuses on the study of the D-T prediction of the two main workhorse plasma heating schemes at JET: H and 3He minority. Both schemes provide different benefits and paths to achieve high-performing conditions in D-T, which are thoroughly discussed. More importantly, the minority concentration range is rigorously studied in order to achieve the optimal benefits from each scheme. Finally, the paper gives an optimal concentration range for each.
2. Effect of inclusion of pitch-angle dependence on a simplified model of RF deposition in tokamak plasma
The calculation of power absorption by resonant particles during radio-frequency (RF) heating is of utmost importance to understand plasma heating physics, transport, and fast particles born from external heating mechanisms. The computation of the power absorption is dependent on the so-called RF diffusion operator.
In this work, we explain how we upgraded its calculation to carefully consider the presence of resonant particles at different energies by means of the velocity distribution function. We validated our results against experimental results and shown that this addition is particularly relevant for low mass particles (as it is usually the case, such as H) and harmonic heating. This work can provide a more precise picture for the expected RF scheme during the activated phase of ITER, the 2nd T harmonic.