A comprehensive investigation has been performed of the static and dynamicbehaviour of detached recombining plasmas in the linear divertor plasmasimulator NAGDIS-II. For stationary plasma detachment, the transitionfrom electron-ion recombination (EIR) to molecular activatedrecombination (MAR) has been observed by injecting hydrogen gas intohigh density helium plasmas. The particle loss rate due to MAR is found tobe comparable to that of EIR. Experiments have also been performed bythe injection of a plasma heat pulse produced by RF heating into thedetached helium plasma to demonstrate the dynamic behaviour of volumetricplasma recombination. Negative spikes in the Balmer series lineemission were observed and found to be similar to the so callednegative ELM observed in tokamak divertors. Observed Balmer spectrawere analysed in detail using the collisional-radiative model. A rapidincrease of the ion flux to the target plate was observed associatedwith the re-ionization of the highly excited atoms generated byEIR.
One-dimensional simulation and validation of divertor detachment induced through nitrogen seeding on HL-2A