Beam alignment of ECH transmission line using moment method

In the 84 GHz CPI gyrotron, with a single-stage depressed collector in the TE/sub 15,3/ oscillating mode, a geometric optics Vlasov converter was installed in the tube to convert the mode into a Gaussian beam. The low power test stand where intensity and phase patterns can be measured was prepared at the National Institute for Fusion Science (NIFS). The sizes and tilt angles of quasi-optical beams are deduced from the measured intensity and phase profiles using the moment method. The Gaussian-like beam is coupled into the HE/sub 11/ corrugated waveguide with tilt angle adjustment. The beam radiated from the waveguide after coupling is analyzed with the moment method. The Gaussian content in the radiated beam is also discussed.