Alignment Method of ECH Transmission Lines Based on the Moment and Phase Retrieval Method Using IR Images

Abstract

New alignment methods of millimeter-wave transmission lines for Electron Cyclotron resonance Heating are proposed and evaluated on a high power level. These methods are based on the measured data of infrared images on the target, which is irradiated by the high power millimeter-waves at several positions. The first and second moments and retrieved phase obtained from these data are used to determine the propagation direction of the millimeter-wave beam along the waveguide axis. It is demonstrated that these methods have sufficient resolution to discriminate 0.1 deg., which is required to restrict the transmission loss below 1% over the 100 GHz range.

The Multiple Gyrotron System on the DIII-D Tokamak

“…The rf beam is propagated into free space for short pulses a few ms in length and hits a paper target placed at a series of locations about 10 cm apart along the beam as it travels away from the gyrotron [26]. Infrared images of the target are made, the sequence of which is subjected to phase retrieval analysis [27,28], which yields both the propagation angle with respect to the gyrotron output flange and the transverse offset of the beam center at the gyrotron output window.…”

Handling Technology of Mega-Watt Millimeter-Waves For Optimized Heating of Fusion Plasmas

“…and 2.9 mm, respectively, for the 168 �H�� transmission through a corrugated waveguide with a diameter of 88.9 mm [Ohkubo et al, 1997]. We have been researching an alignment method for high power millimeter-waves to corrugated waveguides based on infrared (IR) images on a target irradiated by high power millimeter-waves [Ku��ne��ov et al, 1991, Shimo��uma et al, 2005. One method is based on phase information, which is sensitive to the propagating wave characteristics.…”

Development of a Millimeter-Wave Beam Position and Profile Monitor for Transmission Efficiency Improvement in an ECRH System

“…Alignment methods of the corrugated waveguides and methods of a propagating mode-content analysis in the waveguide have been proposed and developed [3][4][5][6]. These methods were based on the measured field pattern on the target plate irradiated from an open edge of the corrugated waveguide.…”