Negative Hydrogen Ion Source 3 D Pic/mcc Numerical Simulation Research

Since the launch of the global ITER project, many scientists have done a lot of work in the plasma of controlled thermonuclear fusion research, based on the high-energy negative hydrogen ion source neutral beam injection. Among them, the multi-cusp magnetic field of negative hydrogen ion source has a great application prospects because of the high yield of the negative hydrogen ions in the neutral beam injection system. The most widely used models of the device in this type of ion source are JAERI10A, J-PARC, JT-60U, Camembert Ⅲ and so on.In this paper, the three dimensional PIC/MCC algorithm is applied to simulate two kinds of negative hydrogen ion source of JAERI10A and J-PARC, which based on the CHIPIC software platform. The main research and achievements of this thesis are as follows:1. Three dimensional finite difference algorithm of rectangular permanent magnet is presented in the Cartesian coordinates. It is translated into program and is added to permanent magnet compute model of CHIPIC soft. Multi-cusp magnetic field of negative hydrogen ion source is calculated accurately by means of the method.2. Three dimensional PIC/MCC algorithm used for numerical simulation of negative hydrogen ion source is realized on the CHIPIC software platform, it is derived by combining the PIC algorithm with the MCC algorithm.3. At first, the three dimensional PIC/MCC algorithm was used to simulate numerically JAERI10A negative hydrogen ion source. The results of numerical simulation showed that non-uniform distribution of electrons is related to multi-cusp magnetic field configuration of extraction region.Then, by changing the distribution of permanent magnet and the structure of ion source, two schemes about space uniformity optimization are put forward. On the one hand, two special multi-cusp magnetic field configuration, external magnetic filter and tent-shaped filter, were analyzed respectively, their influences on electronic energy distribution were compared. The simulation results show that they all can confine diffusion of particles and can extract negative hydrogen ions, their electronic energy distributions are basically similar, presenting double energy state, both of them are consistent with plasma discharge basic mechanism; the former is stronger in confining diffusion of particles, is significantly better able to produce more particles, the tent-shaped magnetic field can efficiently prevent electronic drift caused by inhomogeneous longitudinal magnetic field, leading to more uniform spatial distribution of negative hydrogen ions. On the other hand, by readjusting the structure of ion source rationally, uniform ion beam is obtained.4. By using the three dimensional PIC/MCC algorithm in two different J-PARC negative hydrogen ion sources, discharge mechanism is researched, the relation between efficiency of volume production and position of calibration magnet is analyzed. The results of numerical simulation showed that spatial distribution of the first ion source is uniform and efficiency of volume production is higher, so mechanism of surface production is not necessarily required, the design efforts are relaxed and the production cost is reduced.