| The main subject of this thesis is the implementation of the Electron Cyclotron E-mission Imaging (ECEI) diagnostic technique on the tokamak devices. The focus of this thesis is the integrated design of the large aperture, long focus quasi-optics with focal plane translation and vertical zoom features, the new generation wide band electronics and the 384-channel high speed data acquisition system for the 384-channel ECEI system on the EAST tokamak. The main advantages of ECEI technique are the high spatial and temporal resolutions and the two dimensional diagnostics ability, and the main advance in the 384-channel ECEI system is the much larger radial coverage.Millimeter wave heterodyne mixer antenna array and quasi-optics techniques have already been widely used in radio astronomy, and were creatively migrated to the plasma diagnostic field and then became the prototype of the ECEI diagnostic. The quasi-optics technique is a convenient and efficient way of realizing wide-band low-loss millimeter wave propagation. In 1990s, the integration of the wide-band inter-mediate frequency (IF)electronics to the ECEI system brought the real time two dimensional ability to ECEI diagnostic. This electronics is based on the micro-strip and the print circuit board (PCB)techniques, and the essence of the electronics is the double down conversion process to retrieve the time-resolved intensity information from the raw ECE signals. High speed(?2MISPS),multiple-channel (> 100) data acquisition (DAQ) system have removed the limitation on the time resolution in the DAQ system end, and the ability to communicatewith MDSplus server make the international cooperation of different ECEI systems all over the world easier. Most of the discussions in this thesis are about the design and development of the 384-channel ECEI system on the EAST tokamak, and the detailed discussion starts from the 384-channel DAQ system.The electronics part in the 384-channel ECEI system are about to export 384-channel,400kHz bandwidth, analog voltage signals simultaneously, and the 384-channel DAQ sys-tem is designed to realize the high speed data acquisition and the real time digital data process of these output signals. 12 customized digitizers, each one featured with 32 high speed analog to digital modules and large capacity on-board memory are integrated to form 384 channels. The digitizers are customized to retrieve high common mode rejection ratio (CMRR). Multi-channel, high precision splitters for the trigger and clock signals are used to sync the time bases of all 384 channels, and the system can accept external trigger and clock signal via customized opto-isolator. Well defined multi-ethernet card scheme and the high speed local ethernet have ensured secured high speed data transfer for the ECEI system. The amount of the data acquired in one shot can be up to 7.6 gigabytes, and the data transfer from the DAQ cards to the data server can be done within 30 seconds after each shot. Several basic commands are integrated into various DAQ scripts for multiple DAQ mode and a full automatic DAQ scheme is designed specially for the experiment on EAST tokamak. Multiple remote monitoring ways and error handling abilities are pro-vided for system debugging. The 384-channel high speed DAQ system have already been used in the 2012 EAST campaign, and it have already got 384-channel synced data with high sampling depth and acquisition rate in the regular shots (10s) and the long pulse shots (less than 30s).A novel wide-band electronics is developed for the 384-channel ECEI system to realize the second frequency down conversion process and retrieve a much larger radial coverage.The bandwidth of the novel electronics is at least 2 times as much as that of the other ECEI systems in the world. Since the bandwidth of the electronics is approximately direct proportion to the radial coverage, the radial coverage is basically 2 times as much as the other ECEI systems. The maximum video bandwidth is 400kHz and the fast ion induced modes of which frequency could be ? 100kHz can be resolved by this ECEI system. This novel electronics has already been tested in late 2011 and implemented in the physics experiment of 2012 EAST spring campaign. The larger radial coverage have led to several deeper understandings of some large-scale phenomenons.The design of the quasi-optics is the hardest part in ECEI system design, and it could hardly be shared among different tokamak devices. The quasi-optics design for the new generation ECEI system on the EAST tokamak starts from the calculation of the port interface dimension needed for high resolution high field side imaging. And the actual size of the ECEI window on EAST have lead to a 1cm best vertical resolution. The design is based on the synthetic method of the geometric optics approximation and the gaussian beam propagation models. A large aperture, long focus and thin lens design with the focal plane translation and vertical zoom features is retrieved after many rounds of try-and-error procedures. The maximum vertical zoom factor is about 2.5, and the radial coverage of the focal plane could cover the whole tokamak cross section under the widest zoom configuration. The results from the optics characterization have shown a good consistency with the design. During the tokamak operation, the ability to identify the inversion surface of the sawtooth activity under various discharge conditions and different optical configurations has indicated the realization of the focal plane translation and vertical zoom features of the optics, while the spatial correlation studies during sawtooth precursors have shown that the channel cross-talk level is relatively low.Preliminary imaging results have been retrieved from the 384-channel ECEI system on the EAST tokamak, and the advantage of each part have brought more opportunities of getting higher quality imaging data, and also the experience is accumulated for the future two dimensional imaging diagnostic under high discharge parameters and various auxiliary heating scheme on the EAST tokamak. |
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