Antenna to Core: A New Approach to RF Modelling

Abstract

Abstract.A new technique for the calculation of RF waves in toroidal geometry enables the simultaneous incorporation of antenna geometry, plasma facing components (PFCs), the scrape off-layer (SOL) and core propagation [Shiraiwa et al, "HIS-TORIC: Extending core ICRF wave simulation to include realistic SOL plasmas", Nucl. Fusion in press 10 (2017)]. The calculation of antenna coupling has been traditionally performed separately from those of core propagation whereas this method allows them to be combined permitting the modelling of such phenomena as waves reflected from plasma-vacuum boundary or cyclotron resonances back to the antenna. Calculations with this technique also naturally capture wave propagation in the SOL and its interactions with non-conforming PFCs permitting self-consistent calculation of core absorption and edge power loss.

Effect of poloidal phasing on ion cyclotron resonance heating power absorption

“…the coupling and antenna spectrum, but use more simplified models of the plasma core [8,14]. In [28,29], a modeling technique which is able to have an accurate representation of both the core plasma and the SOL and antenna region is described. This is achieved by using a code based on the FEM to describe the regions outside the separatrix, while the core plasma is described using the TORIC code [21].…”

Recent progress in modeling ICRF-edge plasma interactions with application to ASDEX Upgrade

“…Simulations for Alcator C-Mod show that the computed core RF field pattern with HIS-TORIC is similar to that computed with the regular TORIC code [153]. Later, the Petra-M model [106] (Physics Equation Translator for MFEM) solving the RF wave physics in the SOL was used instead of COMSOL to couple with TORIC [106,107], which allows the simulations to be extended to 3D geometry and run more effectively.…”

“…To further include ICRF core physics, it would be useful to couple an edge antenna and a core ICRF code in one package, such that the wave excitation, propagation and absorption can all be taken into account. To achieve this goal, the HIS-TORIC (hybrid integration of SOL to TORIC) code package is developed to couple a SOL cold collisional plasma model based on COMSOL with the core heating code TORIC [107,153]. The philosophy is to solve the core and SOL physics separately for all boundary Fourier modes, and then join the two domains together using the continuity BC for the tangential electric and magnetic fields at their interfaces.…”

“…This enables PETRA-M to exploit a trade-off between element order and number of degrees of freedom, enabling it to give accurate solutions while solving smaller systems of equations. The Petra-M code had been used for 3D full wave simulations in minority heating regime for Alcator C-Mod [106,107] and the HHFW regime for both NSTX-U and LAPD plasmas including realistic antenna geometries [108].…”

RF wave simulation for cold edge plasmas using the MFEM library

“…Recently we tackled this issue with an alternative strategy, in which we solved core and edge regions separately, but stitch them afterwards. An initial work of this approach ("domain partitioning") was presented at the previous conference [5], and a successful simulation of H-minority ICRF heating on Alcator C-Mod was recently published [6]. In ref 5 and 6, the wave in the hot core plasma was solved by the TORIC spectral solver [7], and the SOL and antenna regions were discretized by unstructured triangles (HIS-TORIC: Hybrid Integration of SOL to TORIC) and solved using a commercial FEM package, COMSOL.…”