Development of Advanced Millimeter - Wave Plasma Diagnostics

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During the period of this research, following subjects were studied under the international collaboration program.(1) Development of millimeter-wave Imaging Arraya) Millimeter-wave two dimensional imaging array has been applied to the GMMA 10tandem mirror. The imaging array successfully measures the three-dimensional profiles of electron density and electron cyclotron emission (ECE). The ECE imaging has also been applied to the RPT tokamak in the Netherlands for the study of electron temperature profiles and temperature fluctuations.b) A novel detector using MMIC technology has been fabricated Teratec Corporation. The heterodyne characteristics of the detector were evaluated at 70-140 GHz. The response of intermediate frequency up to 8-10 GHz was confirmed, which is one order broader than that of a hybrid detector.c) The optics for ECE imaging on Large Helical Device (LHD) were designed and fabricated by using the similar method as the GAMMA 10 system. The Airy pattern of a Point sourc … More e and the magnification factor at 140 GHz were in good agreement with the designed values.2. Development of ultrashort-pulse reflectometrya) The proof-of-principle experiment of an ultrashort-pulse reflectometry using a 65 ps FWHM and 8 V impulse has been carried out. The observed values of time-of-flight agreed well with calculated ones using the Abel-inverted profile from the ineterferometry data. The possibility of simultaneous measurements of density profile and density fluctuations was demonstrated using high repetition of the impulse generator.b) Two-dimensional simulator models to investigate millimeter-wave diagnostics has been presented, which can describe propagation, reflection, and cross-polarization scattering of the ordinary and extraordinary modes.3. Establishment of cross-polarization scattering (CPS) method for diagnostics of internal magnetic fluctuationsa) The CPS experiment has been carried out on GAMMA 10 by using an ultrashort pulse as an incident wave. The effect of wall reflection can be eliminated by the time-of-flight measurements. The received time-of-flight were consistent with those calculated considering mode conversion by magnetic fluctuations.b) The simulation of magnetic field reconstruction by using extraordinary-mode reflectometry and CPS diagnostics has been performed base on the simulator model. The results was compared with the experimental results. Less