Investigation of Electromagnetic Behavior of MACOR for View Dump Application

This article examines the impact of various view dump geometries on their electromagnetic (EM) behavior within the microwave-millimeter range, particularly at frequencies between 60 and 180 GHz. Since the view dump is to be placed inside the tokamak machine, it is expected that the material that is used for its fabrication should have certain required properties, such as low reflection in the desired range of frequencies, sustained at high temperature and high vacuum conditions, low outgassing rate, and low thermal expansion rate. The MACOR material meets all these desired mechanical requirements. For EM absorption capabilities in the desired frequency range, the slab geometry made of MACOR material was first analyzed using CST Microwave Studio. Further, to enhance the EM absorption capabilities of the slab geometry, the slab geometry was modified into various other geometries such as triangular groove, pyramid, inverted pyramid, cone, and inverted cone. In addition, an extensive simulation study was also performed to identify the structural parameters associated with these different geometries, which have the utmost impact on the EM behavior. Experimental investigations for the simulated geometries were obtained by fabricating a prototype of MACOR. The experimental and simulated results for the slab, pyramid, and inverted cone geometries are in good agreement.