NEW ADVANCES OF THE PLASMA VISUALIZATION SYSTEM FOR KSTAR

A 2-D plasma visualization system is being developed for the KSTAR tokamak to image electron temperature and electron density fluctuations. Optical designs are being revised to accommodate a new lens-antenna configuration developed for plasma imaging use. This approach employs an array of miniaturized lenses, with a single imaging antenna placed at the center of each lens, resulting in both increased RF bandwidth and RF sensitivity. Progress is also being made in the development of quasi-optical notch filters that protect the imaging arrays from stray ECRH power. High performance 84 GHz and 170 GHz notch filters have been designed which exhibit large rejection (>35 dB) at the resonant (notch) frequency, and retain this high rejection over an incident angle range of ±10°.