Development Of Field-reversed Configuration Device

Harnessing nuclear fusion energy is believed to be the ultimate way to solve the future energy crisis of humankind.Magnetic confinement and inertia confinement are two mainstream fusion approaches.Though great achievements have been made in both fields,commercializing controlled nuclear fusion energy is still far-reached.In particular,Tokamaks face many formidable challenges,such as complicated engineering,long construction cycle and high cost of construction and maintenance,to name a few.Hence,there are a few universities,research institutes,and companies actively exploring a variety of more economic and compact concepts to realize fusion.Field-Reversed Configuration,with its unique advantages,is a promising candidate for such research.Yingguang-I device was built to study the formation and confinement of the FRC plasma injector for the Magnetized Target Fusion(MTF)at the Institute of Fluid Physics,Chinese Academy of Engineering Physics in 2013.The FRC uses the formation method of ?-pinch.The plasma density is 1016 cm-3,plasma temperature is 200 eV,separatrix radius is 4 cm and lifetime is 3 ?s.The colliding and merging KMAX-FRC device reported in this dissertation is developed on the basis of retaining the characteristics of KMAX(Keda Mirror with Axisymmetricity)tandem mirror.The source region of the FRC is located in the conical chamber on both sides of the main vessel of the KMAX device.Initial FRC plasmas are formed in the source region using?-pinch.The FRC plasmas formed at both ends are ejected by the Loren force generated by the radial magnetic field and the FRC toroidal current,and collided and merged into a FRC in the cetral cell.The plasma temperature,density,and lifetime are respectively,60-100eV??3×1018 m-3 and?300 ?s for the current operating conditions.The KMAX-FRC we have developed is the first colliding and merging FRC in China to author's knowledge,and experiences gained in our work may be instrumental to the development of FRC's commercial fusion reactor,perhaps more importantly is to promote the development of our country's compact fusion research.The main work of this paper is to develop the first experimental device of colliding and merging Field-Reversed Configuration of China--KMAX-FRC at University of Science and Technology of China.In the first chapter of this paper,we analyze the world energy structure and the urgent demand for the development of fusion energy,thus lead to the concept of Field-Reversed Configuration,and discuss the development status and formation technology of Field-Reversed Configuration.From the second chapter to the seventh chapter,we have carried out a detailed description of the development of the KMAX-FRC device,including the antenna system,the pulse energy system,the pulse trigger system,the pulse gas injection system and so on.Among them,two sets of antenna systems are installed in the vacuum chamber of the KMAX device.Each antenna system uses 16 rings of single turn copper as an antenna,and the antenna length is 1025 mm,the diameter is 350,350,400,450 mm respectively.The antenna is wound on the staircase quartz glass tube,and the conical half-angle of the antenna is about 2.8°.The pulse energy system adopts the design mode of 8 sets of high voltage pulse synchronous discharge,and each group of pulses is controlled by four high voltage and high current switches for time series discharge.The time precision needs to reach the magnitude of microseconds and the total energy is 115 kJ.The pulse trigger system is the key to ensure the KMAX-FRC's time series discharge.In the KMAX-FRC device,we use 3 nanosecond delay devices as the timing control source of the 32 high voltage pulse generators,and then control the time series discharge of the FRC.In order to increase the uniformity of gas distribution,we have built four sets of pulse gas injection systems,namely vertical injection and oblique backward injection.It will be described in detail in the seventh chapter.After the design and construction of the KMAX-FRC device,we carried out a series of experiments to measure the parameters of FRC,mainly including the measurement of electron temperature and electron density,the internal magnetic field profile diagnostic,high-speed photography,the measurement of the squeezed flux and the measurement of the velocity of the plasmoid.To measure the FRC profile,we built a set of telescopic and rotatable magnetic probe system,which can perform the radial profile scanning of FRC.In addition,APD light intensity diagnostic system was fabricated,and FRC transmission speed were determined.