Particle-in-Cell Investigation on Temporal Flow and Expansion Behaviors of Deuterium-Titanium Plasmas From Ion Source to Expansion Cup

By using a self-programed circular cylindrical coordinates 2-D, three velocity component, particle-in-cell (2D3V-PIC) code, the temporal dynamic flow and expansion behaviors of deuterium–titanium plasmas from the ion source to expansion cup are numerically studied in this article. The simulation results demonstrate as follows. There is a notable plasma sheath near the wall of the ion source with the electric field intensity on the order of MV/m in the radial direction; this plasma sheath will accelerate ions and decelerate electrons. Compared with Ti ²⁺ ion, the radial dispersion phenomenon of D ⁺ ion is more obvious. The electric field intensity of plasma sheath is first increased and then decreased, which consistently influences the radial dispersion behavior of ions in the expansion cup. Due to the plasma sheath near the wall of the ion source, the ion radial-accelerating effect always exists. Due to the separation between ion and electron, there is also an ion axial-accelerating phenomenon. Moreover, the ion axial-accelerating effect will decrease and, finally, disappear due to the decrease in the separation effect between electron and ion. In the steady phase, the ion current on the extraction wall is higher than the loss of ion current on the wall of the ion source, and the ion extraction efficiency of Ti ²⁺ is much higher than D ⁺ .