The goal of the Phase I research is to develop a preliminary version of antenna sheath analysis tool (ANSAT), a post-processor for the ARGUS code. ARGUS is an existing full wave electromagnetic code which can be used to determine the electromagnetic fields produced by ICRF (ion cyclotron range of frequencies) antennas in the context of ion-cyclotron heating of fusion plasmas. The ANSAT code will use the output from ARGUS to calculate radio frequency (rf)-sheath driving voltages on the Faraday shield of an antenna. In Phase I, critical aspects of the physics and code development will be examined in order to assess the prospects for developing a complete sheath analysis tool in Phase II. A preliminary version of the code will be developed in Phase I to show how the rf sheaths driving voltages can be calculated and employed to assess the strengths and weaknesses of an antenna design with respect to critical voltage handling and edge plasma interaction issues. These issues include hot spots on the screen, weak points with regard to breakdown, ICRF-convective cells, power dissipated in the sheaths, and the influx of impurities resulting from rf-driven sputtering processes at the Faraday shield. Anticipated Results /Potential Commercial Applications as described by the awardee:If successful, the Phases I to III research and development projects will result in a user friendly postprocessing code or suite of codes that will support the design of ICRF antennas operating in fusion plasmas. The codes will provide a unique capability to assess antenna designs for important sheath related phenomena to a degree that is not presently available. Antenna designs will be an important part of upcoming plans for both the Tokomak Physics Experiment (TPX) and International Thermonuclear Experimental Reactor (ITER) tokamaks, as well as possibly IGNITOR, Wendelstein VII-X, and Faraday screenless operation on Joint European Torus (JET). The availability of a sheath antenna design tool will be both timely and marketable to the Federal Government and/or the joint central team of ITER, as well as to the European and possible the Japanese fusion communities.
