Development of the Molybdenum Millimeter Wave Target Tile for ECRH Antenna Alignment after the Evacuation in LHD

Alignment of the quasi-optical millimeter wave antenna for electron cyclotron resonance heating (ECRH) can be required even after evacuation vacuum vessel in fusion oriented plasma experimental devices. We developed a molybdenum target tile and installed it as one protection tiles wall Large Helical Device (LHD) on opposite side ECRH antennas. Inside tile, sheathed thermocouple is mounted to measure temperature increase during injection toward this tile. In magnetic field configurations where neither first nor second (ECR) exists, measured increased sufficiently detected by approximately 100 kW 0.1 s Under assumption that distance between point brings largest just above head gives offset corrected, angle was confirmed with an accuracy 0.4◦ changing shot shot.