Progress on a Laser Inverse Compton Scattering Runaway Electron Diagnostic Design for DIII-D

We report on progress in the design and component testing of a Laser Inverse Compton Scattering diagnostic (i) to measure runaway electrons in the range of 3-30 MeV in the DIII-D tokamak during triggered disruptions. An 80 picosecond, 2-3 Joule, rep-rated Nd:Yag laser is being developed at Voss Scientific. This short-pulse high energy laser is required due to the large background soft x-ray levels and low density of runaway electrons being diagnosed. A 4-channel gated soft x-ray imager (based on ones used at NIF) has been tested on the synchrotron Advanced Photon Source at Argonne National Laboratory. A synthetic diagnostic model is being developed at Woodruff Scientific to optimize design issues, with regards to geometry and choice of filters. Finally, a suitable (tentative) tangential port has been identified on the DIII-D tokamak, and a diagnostic design package is being completed. (i) G. A. Wurden, J. A. Oertel, T. E. Evans, Rev Sci. Instr. 85(11), 11E111, (2014)