Development of one-dimensional plasma transport code and the application to MPS-LD linear plasma device

To investigate plasma transport in the Multiple Plasma Simulation Linear Device (MPS-LD), a one-dimensional (1D) finite-volume (FV) fluid code LDPFT1D for edge plasma transport along the magnetic field is developed and coupled with a Monte Carlo (MC) code MCNT for neutral-particle transport. The coupled code LDPFT-MCNT1D is highly modular and extensible, allowing it to be flexibly adapted to various physical problems. LDPFT1D is benchmarked against the BOUT++ LPD module, and LDPFT-MCNT 1D is compared against experimental measurements from hydrogen plasma discharges in MPS-LD. Overall agreement is obtained in both comparisons, supporting the numerical implementation and physical model. Using LDPFT-MCNT 1D, the effects of H⁻ mediated dissociative attachment molecular activated recombination (DA-MAR) on plasma transport are investigated. The results show that DA-MAR provides an additional H⁺ loss channel in the near target region through dissociative attachment and mutual neutralization. The resulting reduction in the local net particle source decreases the electron density, ion flux, and heat flux at the target. Within the parameter range considered in this study, the contribution of DA-MAR to the total volumetric loss of H⁺ exhibits a pronounced dependence on the electron temperature. DA-MAR is primarily active in the low-temperature range 2 eV < Te < 4.5 eV, where it accounts for approximately 20%–30% of the total volumetric loss of H⁺. These results demonstrate that DA-MAR is an important molecular process affecting hydrogen plasma transport.