First results of multi-fluid modeling of detached hydrogen plasmas in a linear plasma device using fluid code LINDA-NU

In order to simulate hydrogen (H) plasma in the linear plasma device NAGDIS-II, we have modified the fluid code LINDA-NU to allow the simultaneous calculation of multiple ion species consisting of hydrogen atomic ions ($H^{+}$) and molecular ions ($H_2^{+},H_3^{+}$). In this simulation, H and $H_2$ neutrals are assumed to be uniformly distributed in space in order to obtain initial qualitative results. The fraction of $H_3^{+}$ ions increases as the $H_2$ molecular density increases, and the recombination process between $H_3^{+}$ and electrons is observed to reduce the particle flux to the target plate. With an increase in H density, the electron density increases due to the decrease in ion flow velocity due to the change exchange process, and the electron temperature decreases to less than 1 eV, leading to the detached plasma formation attributed to the electron-ion recombination process.