Finite elements method-based ICRF wave heating simulation integrating with SOL plasma for EAST tokamak

Abstract

Ion cyclotron range of frequency (ICRF) waves heating simulation is often carried out in the core plasma region. However, the inclusion of scrape-off layer (SOL) plasma in the simulation model may lead to new physical phenomenon and needs to be studied. In this paper, we apply finite elements method (FEM) based on the approach of [Vallejos 2019], to simulate ICRF waves heating in account of the realistic SOL plasma for EAST tokamak. In the presence of density pedestal near last closed flux surface (LCFS), a kind of cavity mode is observed for the case of low parallel wave number. Near ion-ion hybrid resonance (IIR) layer in SOL region, mode conversion from fast waves to slow waves takes place. ICRF waves coupling characteristics are roughly consistent with the prediction of the dispersion relation except for some small deviations, which may be caused by fast waves reflection in the high field side. Approximate on axis heating of minority H is observed and power deposition zone broadens with parallel wave number increasing. Waves energy dissipation in SOL plasma is less than 7% and localized near IIR region. Furthermore, the comparison between D(H) and D(He-3) minority heating scenarios is also carried out. The results and conclusions in this paper can provide theoretical reference to ICRF heating experiments and may supply a new insight in ICRF waves form in the plasma edge.

Summary of the 10th Conference on Magnetically Confined Fusion Theory and Simulation (CMCFTS)

“…Jiahui Zhang reported the effects of edge density perturbation on the ICRF wave propagation and heating of core plasmas. It is found that, as the scale of density perturbation is comparable to the ICRF wavelength, it may significantly affect the core plasma heating by ICRF [61]. A positive correlation of ICRF scattering to the amplitude and perpendicular scale of the density perturbation was also observed.…”

An alternative method to mimic mode conversion for ion cyclotron resonance heating

“…The way to cope with this is simply to force the linear disturbed plasma density n j to approach zero near the fundamental cyclotron resonance layer for species j. It is also worth noting that the wave equation set here will degrade to the FEMIC circumstance [18,24] if the second term in the bracket of equation ( 16) is neglected…”

“…The advantage of the INTFLUK code is its ability to make a simulation with a realistic SOL and a complicated geometric construction. Inclusion of the SOL is important for analyzing effects such as wave coupling, surface waves around the LCFS and mode conversion in the SOL [24]. The 2D full-wave simulation model for EAST is shown in figure 14.…”

Influences of plasma density perturbations on ion cyclotron resonance heating

“…The finite element method (FEM) based ICRF full wave code integrating the core with the edge, first established by Vallejos [21], has the potential to analyze the influence of plasma density perturbations on ICRH. Previously, we developed this code to carry out the global ICRH simulation on EAST [22]. In this paper, we continue to apply this code to analyze the influence of plasma density perturbations on ICRH for the EAST tokamak.…”