The Key Technology Research Of 140GHz ECRH Transmission Line

Electron cyclotron resonance heating(ECRH) is a kind of attractive auxiliary heating method, and it is the preferred scheme to change plasma temperature, density and current profile and to control plasma magnetohydrodynamics(MHD) instability in the international thermonuclear experimental reactor experiment reaction(ITER), so ECRH experiment research is becoming one of the international frontier topic to carry out magnetic confinement controlled fusion research. ECRH transmission technology research has become increasingly active which is dedicated to achieving high efficiency transmission of megawatt, long-pulse millimeter wave, and the technology for real-time measurement of high power millimeter wave power and the polarization characteristics is one of the hot research topics. These related researchs can provide necessary technical means for the ECRH system?s efficient running and control of the microwave?s injection pattern optimization.Research of the key components in 140 GHz transmission line is the subject of this thesis, and the research is mainly focused on design of the power monitoring miter bend based on apeture-coupling theory and design of the high power polarizer which is based on vector diffraction theory. Transmission efficiency of the ECRH transmission line and the microwave source?s parameters such as input power of the ECRH system can be achieved by microwave power measurement, and in order to control the polarization direction of microwave, study of the high power polarizer is need.The main research content is divided into three parts.1. The ECRH transmission line system is going to be briefly introduced, and some components of the transmission line will be mainly introduced, such as the miter bends and corrugated waveguides. Besides these, loss of the transmission line and coupling efficiency of the fundamental gaussian mode with the 11 HE mode will be analyzed.2. Advantages and disadvantages of several methods for the high power millimeter wave power measuring will be analyzed, and the method of a directional coupler and a millimeter wave power meter is going to be put forward. With a brief introduction of the aperture-coupling theory, in this part, we will carry out structural design and parameter optimization of the power monitoring miter bend to monitor transmitted power of the 140 GHz ECRH transmission line, and the research will focus on the theoretical analysis and the software simulation. Ultimately, parameters of the double-aperture coupling structure will be determined, and tolerance analysis of the double-apertures coupling structure? parameters and machining discussion will be carried out.3. After a summary of the current high power polarizer grooved structures, a cosine grooved structure is going to be presented in this paper. The vector diffraction theory will be introduced briefly, what? s more, we will design the grooved structure of the high-power polarizer and optimize parameters of the grooves by software programming based on vector diffraction theory, and the grooves? parameters of the circular polarizer and the linear polarizer which can change microwave polarization characteristics will be determined. Affect of the grooves? structure parameters to the polarizer?s polarization characteristics, such as groove shape? distortion will be discussed. Tolerance analysis of the grooves? structure parameters and mechanical discussion are going to be carried out. In the end, a low power experimental measurement system of microwave polarization parameters, as well as the relationship between the incident angle to plasma and the polarization characteristics will be discussed.