Study of energy loss processes during hydrogen gas puffing by the PIC simulation

This research numerically studies the formation of a detached plasma and the energy loss processes during hydrogen (H) gas puffing by using the 1D-3 V Particle-In-Cell (PIC) code. In this study, the 1D-3 V PIC with Monte Carlo Collision (MCC) and cumulative scattering angle Coulomb collision has been developed for investigating the kinetic behavior of the detached plasma. The plasma density increases near the target plate with increasing neutral pressure. The flow velocity, the ion temperature, and the electron temperature are reduced toward the target plate when gas puffing is performed by enhancing the charge-exchange (CX), the ionization, and the excitation loss. For the 15 mTorr neutral pressure case, all of the T_e||, T_e⊥, T_i||, and T_i⊥ reduce to less than 1 eV. The heat flux on the target plate reduces with the increment of neutral pressure. The heat flux is remarkably suppressed for the 15 mTorr neutral pressure. The sheath and the presheath potential drop on the target are affected with changing neutral pressure. The power loss terms are enhanced according to the increase of H neutral pressure. For all cases, the CX loss is shown to be higher than 70%. The excitation loss and ionization loss are shown to be nearly 15% and 6%, respectively. The recombination loss is found to be small, but it increases with increasing neutral pressure.