Abstract
A sequence of simulations is performed with RAPLICASOL and SSWICH to compare two AUG ICRF antennas. RAPLICASOL outputs have been used as input to SSWICH-SW for the AUG ICRF antennas. Using parallel electric field maps and the scattering matrix produced by RAPLICASOL, SSWICH-SW, reduced to its asymptotic part, is able to produce a 2D radial/poloidal map of the DC plasma potential accounting for the antenna input settings (total power, power balance, phasing). Two models of antennas are compared: 2-strap antenna vs 3-strap antenna. The 2D DC potential structures are correlated to structures of the parallel electric field map for different phasing and power balance. The overall DC plasma potential on the 3-strap antenna is lower due to better global RF currents compensation. Spatial proximity between regions of high RF electric field and regions where high DC plasma potentials are observed is an important factor for sheath rectification.
| Original language | English |
|---|---|
| Article number | 03020 |
| Journal | EPJ Web of Conferences |
| Volume | 157 |
| DOIs | |
| State | Published - Oct 23 2017 |
| Externally published | Yes |
| Event | 22nd Topical Conference on Radio-Frequency Power in Plasmas 2017 - Aix en Provence, France Duration: May 30 2017 → Jun 2 2017 |
Funding
Simulations were performed with RAPLICASOL and SSWICH-SW to characterize two AUG ICRF antennas. Qualitative features of the experimental observation are well captured by the calculations. Progress was also made for quantitative predictions. We believe the accuracy is constrained by uncertainties in the experimental input and loosely constrained numerical parameters in SSWICH. Repeating the scan in power balance and phasing with a 3D density [19] could help to close the discrepancy. SSWICH-SW only accounts for the slow wave and its mechanism for generating transverse DC current is likely oversimplified. Furthermore, the RF electric field outside the antenna limiters are presently neglected. Replacing it with SSWICH-FW (Full Wave) [16] would bring the fast wave into the mix and open the way to a 3D SSWICH-FW. Acknowledgments This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the European research and training programme under grant agreement N◦633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.
| Funders | Funder number |
|---|---|
| European research and training programme | N◦633053 |
| Horizon 2020 Framework Programme | 633053 |