Influence of expanding and contracting magnetic field configurations on detached plasma formation in a linear plasma device

We investigated the effects of magnetic field structure on detached plasma formation by simulating magnetically expanding and contracting plasma in a linear plasma device. The present study helps to characterize the geometries of a conventional poloidal divertor and advanced divertors, e.g., super-X divertor. The total ion particle flux measured with a large-diameter target plate dramatically changed under the detached plasma condition compared to that in attached plasma. Under the detached plasma condition, the magnetically expanding plasma clearly exhibited a significant influence on the degradation of detached plasma formation. Further, the magnetically contracting plasma slightly enhanced the electron-ion recombination (EIR) processes. By changing the magnetic field structure from contraction to expansion, the electron density (n(e)) decreased and the electron temperature (T-e) increased upstream from the recombination front, leading to the degradation of the EIR processes. The effect of the decrease in parallel flow velocity under the magnetically contracting plasma on the plasma detachment was not observed because the driven flow due to pressure gradient compensated the effect. Published by AIP Publishing.