Bremen 2017 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 21: Plasma Technology

P 21.2: Poster

Mittwoch, 15. März 2017, 16:30–18:30, HS Foyer

Bend for the 28 GHz transmission line on TJ-K — •Enrique Casado Romero, Burkhard Plaum, Walter Kasparek, Gabriel Sichardt, and Günter Tovar — Plasmaforschung, Universität Stuttgart, Stuttgart, Germany

At the stellarator TJ-K, a 28GHz Electron Cyclotron Resonance Heating (ECRH) system will be installed. The oversized transmission line from the gyrotron with TE02 mode output to the stellarator consists of mode converters and a circular polarizer in order to generate a HE11 mode at the end of the 63.5 mm corrugated waveguide. Due to the geometry of the system, it is necessary to integrate a 90° bend. The objective is having an optimal behavior of the bend, with minimum losses and preservation of the HE11 mode. Two options are investigated: the first one is a gradually curved waveguide bend. By optimizing the size and curvature of the bend, one can minimize mode conversion in the bend, i.e. to keep the same mode as in the input. The second option is a low-loss 90° mitre bend at the diameter 123 mm, including a taper from 63.5 mm diameter to 123 mm. By appropriate phase correction of the mitre bend mirror, high transmission efficiency is obtained. Simulations for Gaussian beam and for HE11 mode are performed. We make all the simulations with the programming tool *PROFUSION* created in the IGVP in Stuttgart, which allow us to calculate and simulate fields along waveguides and its different possible components. In the poster, the two designs for the bend are discussed and compared, and first tests of the transmission line components are presented.