Simulation Study on Discharge Characteristics of Microwave Ion Source for Neutron Tube

The discharge in cavity of microwave ion source,an advanced component of neutron tube,was mathematically modeled,theoretically analyzed and numerically simulated with software Comsol for design optimization.The influence of the discharge conditions,including the magnetic field profile,pressure,microwave input power,size and layered materials of cavity-wall,on the electron density was investigated.The results show that a descending impact-factor may exist:magnetic-field distributions > pressure > cavity surface material > cavity-size(microwave-power).For example,the triple permanent-magnet rings provide the gyromagnetic field and confinement of electron and ions;and as the pressure increases,e-density significantly increased.The effect of the microwave power,size and surface property of cavity wall on the e-density was also tentatively discussed.We suggest that the simulated results be of some basic and technological interest in design optimization of neutron tube.