Two-dimensional structure of the detached recombining helium plasma associated with molecular activated recombination

The structural change of the detached plasmas associated with the molecular activated recombination (MAR) has been studied in a high density helium pl asma with helium or hydrogen puff in the linear divertor plasma simulator, NAGDIS-II. The ion particle Aux with the hydrogen gas puff starts to decrea se in the upstream region close to the plasma source, compared to that with the helium puff. The reduction of the ion particle flux along the magnetic field is found to depend on the plasma density. With the hydrogen gas puff , the attenuation of the ion particle flux is getting smaller as increasing plasma density, which is opposite tendency in pure helium detached plasma where the conventional electron-ion recombination (EIR) is dominating. (C) 1999 Elsevier Science B.V. All rights reserved.