Advanced Microwave/Millimeter-Wave Imaging Technology

Abstract

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.

2-D Passive Millimeter Wave Imaging System for Plasma Diagnostics

“…The front end optics must be actively cooled and thermal analysis needs to be performed on the optics. [9] After comparisons with other unit cell structures such as within 15°incident angle is shown is Fig. 6.…”

A large-aperture strip-grid beam splitter for partially combined two millimeter-wave diagnostics on Korea Superconducting Tokamak Advanced Research

“…Several types of quasi-optical components have been employed in millimeter-wave imaging diagnostics on tokamaks: the large-aperture beam splitter, dichroic plate as a high-pass filter, 1 notch filter for system protection, 2,3 and half-wave plate for 90 • rotation of beam polarization. 4 Among them, the beam splitter is widely used to split two beams for a single diagnostic or partially combined two diagnostics.…”

High-power terahertz optically pumped NH3 laser for plasma diagnostics

“…The use of imaging reflectometry [12] will make it possible to visualize the shape and motion of the surface of the critical plasma density in studying collective oscillations or plasma turbulence. Such methods have been previously developed with the use of microwave sources [13] for tokamaks with a plasma density of up to 10 14 cm -3 .…”