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Significant advances in microwave and millimeter wave technology over the past decade have enabled the development of a new generation of imaging diagnostics for current and envisioned magnetic fusion devices. Prominent among these are microwave electron cyclotron emission imaging, microwave phase imaging interferometers, imaging microwave scattering, and microwave imaging reflectometer systems for imaging Te and ne fluctuations (both turbulent and coherent) and profiles (including transport barriers) on toroidal devices such as tokamaks, spherical tori, and stellarators. The diagnostic technology is reviewed, and typical diagnostic systems are analyzed. Representative experimental results obtained with these novel diagnostic systems are also presented.

Understanding the behavior of fluctuations in magnetically confined plasmas is essential to the advancement of turbulence-based transport physics. Though microwave reflectometry has proven to be an extremely useful and sensitive tool for measuring small density fluctuations in some circumstances, this technique has been shown to have limited viability for large amplitude, high kθ fluctuations and/or core measurements. To this end, a new instrument based on two-dimensional imaging reflectometry has been developed to measure density fluctuations over an extended plasma region in the TEXTOR tokamak. This technique is made possible by collecting an extended spectrum of reflected waves with large-aperture imaging optics. Details of the imaging reflectometry concept, as well as technical details of the TEXTOR instrument, are presented. Data from proof-of-principle experiments on TEXTOR using a prototype system is presented, as well as results from a systematic off-line study of the advantages and limitations of...

A 128 channel electron cyclotron emission imaging instrument has been routinely used to study magnetohydrodynamics physics such as m=1 and m=2 modes on the TEXTOR tokamak. As currently configured, each of the 16 mixer array elements measures plasma emission at 8 simultaneous frequencies to form a 16×8 image of electron temperature profiles and fluctuations over an area of 16cm (vertical) by 6cm (horizontal). A redesigned mixer array, coupled with new wideband electronics to be installed later this year, will increase the plasma coverage to 17cm(v)×9cm(h). The new arrangement offers increased temperature resolution together with new gain and video bandwidth controls in a highly modular configuration for ease of maintenance and facilitation of future upgrades both in frequency coverage as well as number of channels.