744 / 2019-07-14 18:44:10

Theoretical study of helium ash transport driven by micro-turbulence in tokamak plasmas

全体主题 > 磁约束核聚变理论与模拟

The alpha particles from deuterium (D)-tritium (T) reaction in tokamak fusion reactor become helium ash after heating plasmas. Removing the helium ash from the core of devices is one of the biggest challenges for the steady and safety operation of fusion reactor.
In our works, we theoretically studied the transport of helium ash driven by ion temperature gradient (ITG) turbulence [1] and parallel velocity shear (PVS) turbulence [2], respectively. Both works found that the efficiency of expelling helium ash through micro-turbulence might become worse when the temperature of helium ash (T_z) becomes lower. Isotopic effects (i.e., increasing the effective ion mass number A_(i, eff)), may be unfavorable (favorable) for expelling helium ash by ITG (PVS) turbulence. Furthermore, we also found that increasing T_z of helium ash could enhance both the level of residual zonal flow (ZF) [3] and ZF linear growth rate [4] driven by collisionless trapped electron mode (CTEM) turbulence. This indicates that higher temperature helium ash may be favorable for improving the confinement of plasmas.
These studies could supply the theoretical references to expel helium ash out and understand the effects of helium ash on plasma confinement in the future burning plasmas.