Burning fraction, radial transport, and steady state profiles of multi-species particles in CFETR burning plasmas

Abstract

The burning fraction of fuel particles is a crucial issue for future fusion reactors. In order to achieve the high tritium burning fraction required by China Fusion Engineering Test Reactor (CFETR) engineering design, fueling depths and quantities should be estimated by particle control analysis for different scenarios. Thus, in this paper, a multi-species fluid model of deuterium-tritium (D-T) fusion plasmas is applied to study radial transport and profile evolution with CFETR parameters under different fueling conditions. In the model, alpha particles are treated with a slowing down model and diffusion coefficients are introduced according to τ E _ 9 8 . Then, in such a self-consistent burning plasma simulation, the results show that the fusion reaction and fueling parameters effect remarkably changes the shape of D/T profiles, while to alphas and helium ash however, the effect of the fueling parameters is much weaker. It is also seen that the burning fraction is increased substantially with the fueling depth, and significantly affected by particle confinement. Furthermore, by substantially raising the D:T ratio to the regime of above unity, the burning fraction can be increased notably, but with a cost of a certain level of fusion power reduction.

Effects of alpha particles on the transport of helium ash driven by collisionless trapped electron mode turbulence

“…The prescribed concentration of helium ash in both ITER and CFETR should be less than 10% [7,8], and successive progress on CFETR further requires 5% as the upper operational limit due to the decrease of fusion power and T burnup fraction by helium ash [9]. α particles from the D-T reaction, acting as the source of helium ash [10], would affect the density profile of helium ash [11,12]. The experiments on TFTR tokamak show that except the very central region, the transport level of helium ash in D-T plasmas is much higher than the prediction from neoclassical theory [13].…”

Estimation of China Fusion Engineering Test Reactor performance and burning fraction in different pellet fueling scenarios by a multi-species radial transport model

“…While the kinetic simulation is computational-time-consuming [13] and the momentum of the fueling source term is hardly estimated both in theory and experiment, the reduced Braginskii [14] equations are used in our model with source and sink terms due to fueling and fusion reaction. As introduced previously [12] and taking the thermal transport into account, the set of model equations is thus written: where the term S D,T is the PI source term, as described in section 4.2. To explore the possibility of satisfying the burn fraction criterion, certain assumptions are made including 100% fueling efficiency and 50:50 deuterium to tritium ratio.…”

“…In section 2, we first start from a zero-dimensional (0D) burning fraction model to make a magnitude estimation of the requirement for future reactor design. Then, a 1D radial transport model introduced in our previous work [12] is modified to take the temperature profile evolution into account and with the pellet deposition described by the neutral gas (NGS) and magnetohydrodynamic (MHD) drift model. This extended transport model with boundary conditions and CFETR parameters applied is described in section 3.…”