The fusion of light nuclei is a promising candidate to supply energy for future generations. The high temperature required for the process can be obtained by coupling radio frequency (RF) power with antennas to the magnetically confined plasma.
A consequence is often the generation of electric fields in the plasma. Rectification in the plasma of components of the RF electric fields produced by the antennas leads to DC electric fields. Processes such as microcircuit fabrication use these electric fields empirically as tools (e.g. to sputter away material). In nuclear fusion, these fields and their effects reduce the effectiveness of an otherwise highly successful heating method.
Theoretical descriptions and numerical simulations are active research topics, but quantitative experimental verifications are missing since they require simple geometries, specific diagnostics and sufficient experimental time; all this is lacking. We will, therefore, utilize a novel dedicated test facility (IShTAR, Ion cyclotron Sheath Test Arrangement) to develop diagnostic methods, validate and improve theoretical predictions, and optimize antennas. The issue is fundamentally related to our understanding of the generation, our ability to measure and our capability to control electric field in plasmas.
A better understanding of these electric fields and their effects will allow an optimisation of the RF heating method in fusion reactors but also improvements in areas where they are used as tools.