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Millimeter wave technology advances have made possible active and passive millimeter wave imaging for a variety of applications including advanced plasma diagnostics, radio astronomy, atmospheric radiometry, concealed weapon detection, all-weather aircraft landing, contraband goods detection, harbor navigation/surveillance in fog, highway traffic monitoring in fog, helicopter and automotive collision avoidance in fog, and environmental remote sensing data associated with weather, pollution, soil moisture, oil spill detection, and monitoring of forest fires, to name but a few. The primary focus of this paper is on technology advances which have made possible advanced imaging and visualization of magnetohydrodynamic (MHD) fluctuations and microturbulence in fusion plasmas. Topics of particular emphasis include frequency selective surfaces, planar Schottky diode mixer arrays, electronically controlled beam shaping/steering arrays, and high power millimeter wave local oscillator and probe sources.

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Twelve ballet dancers with various levels of dancing experience and skill were examined with the visual suppression test using post-rotatory nystagmus (PRVST) and caloric stimulation (CVST). The PRVST results showed a suppression rate that was higher than in untrained subjects. The CVST results showed a suppression rate similar to that in untrained subjects. A correlation between the PRVST and CVST suppression rates and the length of dancing experience showed that the suppression rate increased as the level of experience and skill rose. These results indicate that the PRVST and CVST can aid in the clinical and quantitative assessment of the function of the central nervous system in visual-vestibular interactions in ballet dancers. Additionally, testing may have determined function of vestibulo-cerebellar pathways through habituation of visual-vestibular interactions. Findings indicate that it may be possible to use suppression rates of PRVST and CVST to determine the approximate level of a dancer's experience and skill.

In this article, we describe the electron cyclotron emission (ECE) imaging system applied to the Large Helical Device (LHD) at the National Institute for Fusion Science. The imaging system consists of focusing optics installed inside the vacuum chamber of LHD and planer-type detectors fabricated by monolithic microwave integrated circuit technology. The detector consists of the integration of a bowtie antenna, a down-converting mixer using a Schottky barrier diode, and heterojunction bipolar transistors (HBTs) on a GaAs substrate. The HBTs work as an intermediate frequency (IF) amplifier with a 10 GHz bandwidth and a 10 dB voltage gain. The ECE signal and local oscillator beam are irradiated from both sides of the detector. The ECE signals are down-converted at the mixers and the IF signal is fed to a filter bank with center frequencies of 1–8 GHz. The time evolution and the intensity of the ECE signals agree with those obtained by a conventional ECE heterodyne receiver. The cross-correlation spectra of the signals obtained with different IF frequencies (radial correlation) and different detectors (poloidal correlation) are obtained.

For plasma diagnostic imaging systems such as the electron cyclotron emission imaging (ECEI) system, spurious rf heating power may saturate or even damage the mixer arrays. Without protection, the sensitivity of the mixers can significantly decrease or in the extreme case, the diodes can even be burnt. A metallic dichroic plate is usually used to rejection the spurious rf heating power. However, as a high pass filter, the dichroic plate can not be used when the frequency of the heating power is in the middle of the frequency range of interest. Consequently, a frequency selective surface (FSS) has been introduced as a planar filter in ECEI systems. FSSs can work as low pass, high pass, and band stop filters according to the various system requirements. Also, as a thin, light, planar filter, it is very easy to mount in imaging systems. This paper will focus on the design and fabrication of the FSS notch filter applied in TEXTOR, which is used to protect the imaging array from stray 140 GHz ECRH power. The filter is used in TEXTOR due to its deep rejection, and excellent angle insensitivity. The design procedure will be presented. More FSS applications will be talked in this paper. The new fabrication technique Electro Fine Forming (EF2) technology will also be introduced. FSS filters in the millimeter wave range also have possible applications in imaging systems in other fusion machines such as KSTAR, DIIID, and LHD.