Design And Research Of An Advanced Cesium Oven For The Negative Ion Source In The N-NBI System

In recent decades,many countries have built various fusion devices to realize the commercialization of nuclear fusion,and magnetic confinement fusion has developed unstintingly.In order to realize magnetic confinement fusion,one of the difficulties to be solved is to heat the plasma to more than 100 million ?.Researchers around the world have studied various heating methods,among which the heating effect is the most significant,and the clearest physical mechanism is the neutral beam injection(NBI)heating system.However,with the larger and larger fusion devices built,the heating power required is getting higher and higher,and the positive ion neutral beam inject(PNBI)system has been difficult to provide higher energy neutral beam particles due to the limitations of its physical properties.In recent years,many countries have been devoted to the research and construction of the heating system of negative ion neutral beam injection(N-NBI)which can provide higher energy particles for fusion devices.In 1970,it was found that cesium injection can increase the yield of negative ions.It is a common practice to feed cesium to a negative ion source to increase the density of negative ions.Accurate injection of cesium into negative ion source has become an important research topic in the development of negative ion source.In this paper,an advanced cesium oven system for injecting cesium vapor into a negative ion source is studied and designed.The cesium vapor flux is controlled by controlling the temperature of the oven body,and the injection of cesium vapor is precisely controlled by an external detection device.The main conclusions of this thesis are as follows:1)Based on Solid Works software,the design scheme of the advanced cesium oven is made,and the 3D model diagram of the advanced cesium oven is given,and the design is briefly described.The finite element analysis of the advanced cesium oven system is carried out,and the temperature of each point,the thermal stress and the thermal shape variable generated by heating are analyzed.The simulation verifies the reliability and rationality of the design.At the same time,the temperature variation of the heating wire in the cesium oven under the rated power is simulated,and the reliability of the heating time are analyzed.The variation of caesium vapor flux with temperature at different temperatures is simulated,which provides a reference for caesium spray gun to be used in experiments;2)The corrosion of cesium to iron was simulated by using LAMMPS molecular dynamics software at six different temperatures by adjusting the temperature,and the corrosion process was further explained by calculating the radial distribution function.By calculating the corrosion of cesium to iron,it is concluded that cesium has a certain corrosion effect on iron.Therefore,in order to prolong the service life of the cesium oven,it is necessary to protect the inner wall of the cesium oven with coating.