Plasma Visualization Diagnostics For The Kstar Tokamak

To understand the fundamental physical phenomena of the hot confinement plasma located inside of the controlled fusion experimental devices called Tokamaks, good spatial and temporal measurements of the electron temperature and density fluctuations are needed. Two powerful plasma visualization diagnostics, Electron Cyclotron Emission Imaging (ECEI) and Microwave Imaging Reflectometry (MIR), have been developed by the plasma diagnostic group in University of California at Davis. Unlike the conventional 1-D diagnostic methods, they are able to provide 2-D high resolution image of the electron temperature and density fluctuations.This dissertation will focus on the development of the ECEI system customized for the KSTAR tokamak in Korea. The physics principle of the electron cyclotron radiation in fusion plasmas is firstly reviewed, followed by a description of the system architecture of the ECEI diagnostic. Technology advancements in a variety of the system components are discussed, including the miniature elliptical substrate lenses, dual-dipole antennas and mixers array, quasi-optical planar filters, double down-conversion heterodyne electronics, and local oscillator power coupling. Particular emphasis is given to the design methods and major innovations in the advanced optical coupling system for the KSTAR ECEI. This includes step-by-step descriptions on the imaging lens design analysis, as well as the realization of the advanced imaging features, such as independent zoom and focus control. The development of the frequency selective surface (FSS) notch filter is also discussed in detail. The FSS's basic configurations, design principles, and the numerical design tools will be discussed. The previous notch filter designs as well as the new generation multilayer configuration, which brings significant performance improvements, will be summarized. The laboratory testing platform and the fabrication considerations will also be presented. The KSTAR ECEI diagnostic, fabricated and installed in 2010, represents a new benchmark in imaging diagnostic system in terms of plasma coverage, resolution, and imaging flexibility. It also represents a major step forward in the standardization of many ECEI system components, such as dual detector array with mini lens and planar quasi-optical filter components.