Nuclear Fusion (Jan 2024)
Ti/Te effects on transport in EAST low q95 plasmas
Abstract
Enhanced confinement is observed in EAST low ${q_{95}}$ ( ${q_{95}} < 3.5$ ) plasmas with the temperature ratio ( ${T_i}/{T_e}$ ) increasing. A statistically significant positive correlation between ${H_{98y2}}$ and ${T_i}/{T_e}$ has been established. Increased ${T_i}\,$ triggerd by Neutral Beam Injection in experiments maintaining constant ${T_e}$ leads initially to an improved ${T_i}/{T_e}$ ratio, which subsequently mitigates heat transport in the ion channel. The Trapped Gyro–Landau Fluid transport model was applied to analyse the dependence of the turbulent transport on ${T_i}/{T_e}$ . Simulation results demonstrate that the Ion Temperature Gradient mode is stabilized in high ${T_i}/{T_e}$ plasma, with ion flux results from predictive modelling further validating this effect. These findings corroborate the Weiland model and complement one another. This study contributes to a deeper understanding of how the dimensionless parameter ${T_i}/{T_e}$ influences plasma transport, and helps demonstrate the feasibility of operations under the low ${q_{95}}$ condition required for the ITER-inductive scenario in the new ${T_i}/{T_e}$ regime.
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