European transport simulator modeling of JET-ILW baseline plasmas: predictive code validation and DTE2 predictions

Abstract

The European transport simulator is a fusion machine simulator useful for making predictions of high-performance fusion plasmas, in particular for DT reactors. Recent developments introducing self-consistent simulations of combined RF + NBI heating schemes in which majority, minority and beam ions are simultaneously heated is documented. The predictive simulations are first validated by comparison with the experimental data on a DD JET baseline plasma. In order to prepare the next JET DTE2 experimental campaign, extrapolations of fusion performance on DT plasma from DD plasma are made with a particular focus on ion cyclotron resonance heating (ICRH) computation. Traditional ion cyclotron range of frequency heating models do not permit the study of Coulomb collisional interaction of various ion species simultaneously including neutral beam injection ions, and generally forces one to consider only minority populations. Accounting for multi-population interaction is made possible here by solving coupled sets of Fokker–Planck equations for all ion species adopting the non-linear collision operator for arbitrary distribution functions, accounting for effects, such as the self-collisions of majority (or large minority) populations. To answer the question whether H minority scheme or 3He minority ICRH scheme is better for boosting the DT fusion performance, minority concentration scans are produced.

Simulation of heating and current drive sources for scenarios of the ITER research plan

“…For the specific example at hand, this is the case: the neutron rate associated with 9 Be-p reactions is reduced by an order of magnitude because the wave power is spread over a wider region, yielding lower tail energies and hence less reactions. This effect was already demonstrated in [6] and has recently been confirmed by simulations [30] using the FUSREAC code for calculating nuclear reactions [18,31].…”

Modelling performed for predictions of fusion power in JET DTE2: overview and lessons learnt

“…Such studies continued in campaigns that are more recent. Two independent modelling efforts found similar results for the prediction of the baseline discharges 92 436 [49] and 96 482 [50,51], respectively. Predictive simulations in temperature (T e0 = 8.5 keV, T i0 = 10.8 keV for the H scheme and T e0 = 8.3 keV, T i0 = 11.2 keV for the 3 He scheme) for a 50:50 D-T prediction of 92 436 were achieved using ETS/CYRANO.…”

Maximising D − T fusion power by optimising the plasma composition and beam choice in JET

“…The starting point for a more in depth study is a set of simulations documented in [6]. Huynh adopted the parameters of JET discharge 92436-which was executed with a D majority, using D beams and a H minority concentration of ≈ 1.7%-but changed the plasma composition to a balanced D and T, a mixed D and T beam and allowing both for H and 3 He minorities, adjusting the magnetic field and frequency to ensure a maximum absorbed power density at the same location slightly away from the magnetic axis.…”

“…Because the various populations collisionally interact, also species not directly heated indirectly feel the impact of the heating and hence it is not possible to disentangle the exact role of each individual heating mechanism. In [6] as well as [16] it is shown that when dropping the RF power to zero or to very small levels while adopting the same (imposed) bulk temperatures reduces the fusion power by 2-3 MW. Applying 5 MW of power to a JET-size plasma in absence of beams would yield much lower temperatures and would reduce the fusion power to a negligible level.…”

“…One element of the optimisation is to determine the appropriate plasma composition. Huynh et al [6] studied the optimal choice of the minority species and its concentration. The two classical choices are a H or 3 He minority, both heated at their fundamental cyclotron frequency which coincides with the second harmonic resonance of either the D population (when using H) or the T population (when using 3 He).…”