Validation of a plasma burn-through simulation with an ECH power absorption model in KSTAR

An electron cyclotron heating (ECH) power absorption model was integrated with a plasma burn-through simulator, DYON, and the new version, DYON-EC, was validated against KSTAR ECH-assist start-up experiments. The absorbed ECH power was calculated with an analytic formula which is a function of the electron density and electron temperature and ECH hardware settings, namely, the injected power, wave frequency, harmonic number, mode fraction, and beam injection angles. Wave parameter changes by wall reflection was also included to simulate multiple reflections. The absorbed ECH power was self-consistently included in the electron energy balance equation. The simulation settings of the plasma-wall interaction model and the electromagnetic scenario including the eddy current model were optimized to reproduce the plasma parameter evolution and line emission data in a pure ohmic start-up discharge. The study revealed that assumption of double-path EC beam absorption is required to reproduce a KSTAR ECH-assisted start-up discharge. Using the same optimized settings, DYON-EC modelling successfully reproduced multiple KSTAR EC-assisted discharges in a large range of operation parameters. The good statistical reproduction of measured plasma parameter evolution confirms the validity of the DYON burn-through modelling with ECH.

Automated summary

An electron cyclotron heating (ECH) power absorption model, DYON-EC, was developed and validated against KSTAR ECH-assist start-up experiments. The absorbed ECH power was calculated based on electron density, temperature, and hardware settings, with consideration of wave parameter changes due to wall reflection. The DYON-EC model successfully reproduced multiple KSTAR EC-assisted discharges using optimized simulation settings, confirming its validity.