Design of the upgraded TJ-II quasi-optical transmission line

TJ-II plasma start-up and heating are performed by electron cyclotron resonance waves with a frequency of 53.2 GHz at the second harmonic. Two quasi-optical transmission lines transmit the microwave power. The first line launches the microwave power under fixed injection geometry. To get more flexibility in experiments on heating and current drive the first transmission line is being upgraded. The design is presented here. An internal mirror focuses the beam and changes the injection angle. A polarizer consisting of two corrugated mirrors is incorporated to get the appropriate wave polarization. Two mirrors with an array of coupling holes and calorimetric measurements of the energy absorbed in the barrier window allow the estimation of the microwave power launched into the TJ-II.