Numerical study on ion filtering of titanium hydride cathodic vacuum arc plasma through a double-layer extraction grid

Abstract

A novel method of filtering titanium hydride cathodic vacuum arc ions through a double-layer extraction grid is proposed in this paper. Two grids with different transmission rates are placed very closely, and apertures of the two grids are staggered. Due to the differences of ions in the charge state and kinetic energy, H + can easily go through the second grid after passing the first grid and then be extracted, while most Ti i+ (i=1∼3) are blocked and absorbed by the second grid. Using a 2D electrostatic particle-in-cell simulation, the effectiveness of the double-layer extraction grid on ion filtering is verified. The results show that the fraction of H + can be increased from 39% to 80% by the double-layer grid and the fraction of metal ions decreases significantly. The fraction of H + depends on the distance and the overlap length of the two grids. Besides, in a wide range of extraction voltage, the double-layer grid is effective in increasing the fraction of H + .

Cathode and plasma phenomena in vacuum-arc sources of hydrogen isotope ions: I. Desorption of hydrogen isotopes during the operation of vacuum arc cathode spots

“…Historically, the efforts aimed at improving the efficiency of vacuum neutron tubes with arc ion sources (increasing neutron yield, enhancing stability, and lengthening lifetime) were mainly focused on optimizing the source design and electrical circuit and on increasing the efficiency of hydrogen isotope extraction from the arc plasma (see, e.g. [6][7][8][9] and other publications). At the same time, the processes occurring directly in a vacuum-arc ion source remained poorly understood.…”

Metal ion filtering of vacuum arc ion source through an inclined-aperture extraction grid

“…By accurately setting the inclination angle of each aperture, we can make every grid aperture effective for increasing H + ion fraction. But this is much more difficult for the double-layer grid we studied in [11] because of more complex structure. Similar to the double-layer grid, another function of the inclined-aperture extraction grid is to block metal vapor.…”

“…In our previous paper [11], we have reported a new method of filtering metal ions, which utilizes a staggered double-layer grid to block heavy ions. In this method, the parameters of the two grids are specially designed so that light ions can be extracted under the action of transverse electric fields, while most of heavy ions are blocked by the grids.…”

Numerical study on variable aperture extraction grids of a titanium hydride cathodic vacuum arc ion source

“…The first one is the ideal uniform distribution as presented in figure 6a. Although the uniform distribution is difficult to achieve in experiments, it is still widely used for numerical study for the comprehension of vacuum arc discharge plasma [12,13]. The second one is the Gaussian distribution.…”

“…The methods to increase the extracted H + /D + ion fraction have been widely studied experimentally and theoretically. These methods are based on the magnetic field to filter out metal ions [9], the filter based on the difference of angular distribution of light nonmental ions and metal ions during vacuum arc plasma expansion [10,11], the specially designed extraction grid including double-layer and inclined-aperture ones [12,13].…”