Gyrokinetic turbulent transport simulations on steady burning condition in D-T-He plasmas

Abstract

Ion temperature gradient(ITG) and trapped electron modes(TEM) driven turbulent transport in an ITER-like plasma is investigated by means of multi-species gyrokinetic Vlasov simulations with D, T, He, and real-mass kinetic electrons including their inter-species collisions. Beyond the conventional zero-dimensional power balance analysis presuming the global energy and particle confinement times, gyrokinetic-simulation-based evaluation of a steady burning condition with He-ash exhaust and D-T fuel inward pinch is demonstrated. It is clarified that a significant imbalance appears in the turbulent particle flux for the fuel ions of D and T, depending on the D-T density ratio and the He-ash accumulation. Then several profile regimes to satisfy Reiter's steady burning condition are, for the first time, identified by the gyrokinetic simulation. Also, the impacts of zonal flows and nonthermal He-ash on the optimal profile regimes are examined.

Figures (8)

• Figure 1: Ignition curves influenced by He-ash accumulation($n_{\text{He}}/n_{\text{e}}$) and the steady burning curves for $\rho_{\tau}\! := \!\tau_{\text{p}}/\tau_{\text{E}}$, where $\tau_{\text{p}} \! \simeq \! \tau_{\text{He}}$. See also Ref. 14 and 15.
• Figure 2: Normalized linear growth rate and mode frequency of ITG($\omega_r<0$) and TEM($\omega_r>0$) instabilities in pure-D, pure-T, D-T($n_{\text{D}}\! =\! n_{\text{T}} \! =\! 0.5n_{\text{e}}$), and D-T-He($n_{\text{D}}\! =\! n_{\text{T}} \! =\! 0.4n_{\text{e}}$, $n_{\text{He}}\! =\! 0.1n_{\text{e}}$) plasmas.
• Figure 3: Time evolution of (a)turbulent energy flux and (b)particle flux in the ITG-TEM turbulence of D-T-He plasma. (c)Temperature fluctuations at $t = 65.4R_{\mathrm{ax} }/v_{\mathrm{tH} }$ of D(blue), T(yellow), and He(red). The fluctuations are simultaneously visualized by the superposition of differently colored luminescence.
• Figure 4: Distributions of the turbulent particle fluxes along the field lines in the D-T plasma and the single-ion approximated plasma with the effective ion mass $A_{\text{eff}}$. The flux surface of $\rho=0.5$ is displayed by the curve in green.
• Figure 5: D-T ratio dependencies of the mean (a)energy and (b)particle fluxes of D and T for He-ash accumulations of $n_{\text{He}}/n_{\text{e}}$ = {0%(solid), 5%(dotted), and 10%(dashed)}, where the ion fluxes are normalized by the electron ones. The D-T ratio corresponding to the balanced flux is shown by the vertical line.