Numerical Simulation On The Designing Optimization Of Plasma Switch With Cold Cathode

In the work of pulsed power modulation, traditional vacuum switch devices have some limitations. For example, there will be some problems that the device load is minor, the response cutting-edge is instability, the lifetime is short, etc.. Therefore, in the process of high-power modulation, a low pressure switch is used generally. From the theoretical analysis, the characteristics of low-pressure switching device are following three aspects during working.①The plasma, as a carrier which formed in the gas discharge, turns high-power pulse;②The sensitivity on the voltage changing of the gas discharge between plates is used to complet) the rapid response of the pulse modulation;③It is taken to control the extent of secondary electron emission of cathode so that the purpose of increasing device lifetime could be achieved.In order to design a switch device that is provided with the advantages of the thyratron and the hard tube, and optimize a plasma device with pulse current conduction, FDTD and YEE mesh method are used, with Xoopic software, for numerical simulation on the active process of the switch device. This article includes:1. It is analysed that the emergence of preionization and stability of ionization region which are influenced by electric potential difference between source grid and control grid, relation of relative position on two grids and hole diameter of grids, and distribution of electrical magnetic field, etc. The numerical range of the relevant physical quantity on the grid and the reasonable limits of electromagnetic field configuration are identified for optimally employable state. Effective assist is provided for optimization of the switch device designed.2. It is also analysed that the density of plasma generated by ionization which are influenced by gas pressure in the device, and the region of gas discharge controlled by the magenetic field which is applied on the device. In the meanwhile, with a necessary theoretical analysis on cathode sputtering, the authors elementary ascertain the qualitative range of the magenetic field. Theory basis is provided for optimization of the switch device designed, which lays the foundation of a further research.3. We make a simulation analysis of the secondary emission coefficient of cathode material, the secondary emission level, and electromagnetic field distribution with the impact on the conduction and working process stability of switch. It is determined the factors which influence the discharge status and ignition time of the system, and effective modulation of a peak pulse current. At the same time it is analyzed to reduce the cathode sputtering, and extend the device lifetime.