Multiple-isotope pellet cycles captured by turbulent transport modelling in the JET tokamak

TL;DR

This paper demonstrates the first successful simulation of a multiple-isotope pellet cycle in a tokamak using reduced turbulent transport modelling, aligning well with experimental data and supporting future fusion reactor fuel management.

Contribution

It introduces a novel integrated simulation framework that accurately reproduces pellet cycles in a multi-isotope plasma using reduced turbulence models.

Findings

Successful reproduction of pellet cycle and isotope penetration times

Good agreement between reduced turbulence model and high-fidelity simulations

Implications for improved fuel management in future reactors

Abstract

For the first time the pellet cycle of a multiple-isotope plasma is successfully reproduced with reduced turbulent transport modelling, within an integrated simulation framework. Future nuclear fusion reactors are likely to be fuelled by cryogenic pellet injection, due to higher penetration and faster response times. Accurate pellet cycle modelling is crucial to assess fuelling efficiency and burn control. In recent JET tokamak experiments, deuterium pellets with reactor-relevant deposition characteristics were injected into a pure hydrogen plasma. Measurements of the isotope ratio profile inferred a Deuterium penetration time comparable to the energy confinement time. The modelling successfully reproduces the plasma thermodynamic profiles and the fast deuterium penetration timescale. The predictions of the reduced turbulence model QuaLiKiz in the presence of a negative density gradient following pellet deposition are compared with GENE linear and nonlinear higher fidelity modelling. The results are encouraging with regard to reactor fuelling capability and burn control.