Advanced Quasi Optical Launcher Systems

Recently completed electromagnetic analysis and synthesis codes have been used to generate efficient designs for Vlasov-Denisov-type quasi-optical (QO) launchers in gyrotrons. However, significant improvements still can be achieved over existing QO launcher and mirror transmission approaches. Examples of advanced QO launcher concepts include compact QO launchers, coaxial mode QO launchers, step-tunable launchers, and systems for direct coupling of cavity mode power to corrugated waveguide. In this project, existing codes, developed for the analysis and design of Vlasov-Denisov type QO launchers, will be modified to increase capability and computational speed. These codes will then be used to design advanced QO launcher systems that are relevant for gyrotrons for the International Thermonuclear Experimental Reactor, the DIII-D tokamak at General Atomics, and the ASDEX tokamak in Germany. In Phase I, the QO launcher analysis and synthesis codes were extended to increase their speed and capability. Using the extended synthesis code, a large improvement was achieved in the design of a two-frequency launcher. The extended analysis code allowed a rapid calculation of scattering. Phase II will perform additional optimization and extensions of the QO launcher analysis and synthesis codes. The improved codes will be used to design a compact launcher and a multi-frequency coax launcher. The launchers then will be built and tested. Commercial Applications and other Benefits as described by the awardee: The QO launcher systems should reduce electron-cyclotron heating-system costs by approximately 10%, allowing gyrotron systems to be more compact. The technology also should increase the efficiency of launcher systems and deliver more power to the tokamak plasma. Other applications include the stabilization of neoclassical tearing modes, plasma diagnostics, and spectroscopy (including electron paramagnetic resonance spectroscopy).