First-principles-based multiple-isotope particle transport modelling at JET

TL;DR

This study uses a first-principles-based gyrokinetic model to accurately simulate core particle transport in mixed isotope plasmas at JET, revealing invariant isotope ratios and peaking behaviors consistent with experimental observations.

Contribution

It demonstrates the successful application of the QuaLiKiz model within JINTRAC for predicting isotope transport and profiles in mixed H-D plasmas, validating against experimental data.

Findings

Both H and D profiles are predicted to be peaked regardless of isotope source.

The isotope ratio remains nearly invariant and tied to the electron density profile.

Simulation results are robust against boundary condition and physics setting variations.

Abstract

Core turbulent particle transport with multiple isotopes can display observable differences in behaviour between the electron and ion particle channels. Experimental observations at JET with mixed H-D plasmas and varying NBI and gas-puff sources [M. Maslov et al., Nucl. Fusion 7 076022 (2018)] inferred source dominated electron peaking, but transport dominated isotope peaking. In this work, we apply the QuaLiKiz quasilinear gyrokinetic transport model within JINTRAC flux-driven integrated modelling, for core transport validation in this multiple-isotope regime. The experiments are successfully reproduced, predicting self consistently $ j $, $ n_{e} $, $ n_{Be} $, $ T_{e} $, $ T_{i} $, $\omega_{tor}$ and the isotope composition. As seen in the experiments, both H and D profiles are predicted to be peaked regardless of the core isotope source. An extensive sensitivity study confirmed that this result does not depend on the specific choices made for the boundary conditions and physics settings. While kinetic profiles and electron density peaking did vary depending on the simulation parameters, the isotope ratio remained nearly invariant, and tied to the electron density profile. These findings have positive ramifications for multiple-isotope fuelling, burn control, and helium ash removal.