Development Of IR/Visible Integrated Diagnostics System And The Experimental Results On EAST Tokamak

Experimental Advanced Superconducting Tokamak(EAST) is a fully superconducting tokamak, aimed at achieving high power and long pulse steady-state operations. Long-time interactions between the plasma and the tokamak device could lead to overheating of the first wall, which is a serious challenge for the security of the first wall. In order to protect the first wall, the real-time temperature monitoring of the first wall and the studies on heat flux on the divertor under the different conditions are very essential. Moreover, the runaway electron are need to be monitored.Motivated by the above discussion, this paper focuses on the development and application of the Infrared/Visible integrated diagnostics system on EAST, and the development of the heat load calculation program for the water-cooled divertor with the temperature measurement by the infrared system. Furthermore, the characteristics of heat flux distribution onto the first wall under different conditions and the runaway electron behavior also have been studied. The main research and innovation of this thesis are as follows: 1.Development and application of the Infrared/Visible integrated endoscope.The development and application of the Infrared/Visible integrated diagnostics system and its parameter calibration has been completed. In the endoscope system, the pinhole imaging principle and spectroscope were used, which makes the system with a wide angle of 47o×58o and enables to acquire images of the temperature and the visible radiation of the EAST at the same angle of view. The Infrared/Visible endoscope system was located in the K port, which can monitor the N-port?O-port?P-port?LHW antenna?movable limiter?inner wall?upper and lower divertors. In order to improve the measured precision of the temperature, a black body furnace has been used to demarcate the transmission coefficient of the endoscope system and the emissivity of graphite is demarcated.2.Data acquisition and processing of IR/Visible integrated diagnostic system.The IR/Visible cameras data acquisition, real time data upload process and the image dithered using stabilization technology are developed. Clock synchronization for each data acquisition system is vital to experimental analysis on EAST. The IR/Visible cameras also need to receive trigger signal sent by the central clock system for triggering data acquisition. Based on C++ program development, a set of IR/Visible data real-time acquisition and upload process is established, which can realize real-time upload data to a large data server for data sharing. 3. Design and development the program code for the divertor heat flux calculationBased on the temperature measurement by the infrared system, the heat load calculation program for the water-cooled divertor has been developed. And the numerical method for solving heat conduction for semi-infinite body considered the thermal resistance of surface layers is given. The program is the basis of analyzing the characteristics of heat flux on the first wall under different condition. 4.The studies of heat flux on the divertor and the runaway electron behaviorThe characteristics of heat flux on the first wall under different conditions and the runaway electron behavior have been studied based on the IR/Visible images. Several minor disruptions have often been observed before the major disruption under the high plasma density in EAST. During the minor disruption, the heat fluxes are mainly deposited on the upper/lower divertors. As for the VDE disruption, under the heating power of 1MW on the EAST device, the maximum heat flux received on the dome plate can be up to 11MW/m2, and the spatial distribution of heat flux exhibits strong toroidal and radial asymmetries. And the behaviors of the runaway electrons including the effects of the hybrid waves(LHWs) and Neutral beam injection(NBI) are investigated. It is found that the fast electrons excited by LHWs can be accelerat-ed to runaway electrons during the initial phase of the LHWs injection. Follow, the runaway electrons generation is mitigated by the reduction of the electric field as the LHCD injection.