An Alternative Optical Concept for Electron Cyclotron Emission Imaging (ECEI)

The implementation of advanced ECEI systems on tokamak experiments has revolutionized the diagnosis of MHD activities and improved our understanding of instabilities, which lead to disruptions. It is therefore desirable to have an ECEI system on ITER. However, present ECEI systems require large access ports and employ cumbersome optical components that have, up to now, precluded the implementation of such an ECEI system on ITER. This poster describes an alternative optical ECEI concept that utilizes a single spherical mirror as the primary optical component and exploits the astigmatism of such a mirror to produce an image of the radiating plasma with one-dimensional spatial resolution on the detector. Since this alternative approach would only require a thin slit as the viewing port to the plasma, it would make the implementation of an ECEI system on ITER feasible. Experimental results from laboratory characterization of this optical system are presented and compared to numerically simulated results. Possible approaches to implementing this ECEI system on ITER are also discussed.