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(EXP4/29) Static and Dynamic Behaviors of Plasma Detachment in Divertor Simulator NAGDIS-II

S. Takamura¹⁾, N. Ohno¹⁾, Y. Uesugi¹⁾, D. Nishijima¹⁾, M. Motoyama¹⁾, N. Hattori¹⁾, H. Arakawa¹⁾, N. Ezumi²⁾, S. I. Krasheninnikov³⁾, A. Pigarov³⁾, U. Wenzel^4)
 
1) Department of Energy Engineering and Science, Graduate School of Engineering, Nagoya, University, Nagoya 464-8603, Japan
²⁾ Nagano National College of Technology, Nagano 381-8550, Japan
³⁾ University of California at San Diego, La Jolla, California 92093-0411, USA
⁴⁾ Max-Planck-Institut für Plasmaphysik, EURATOM Association, D-1011 Berlin, Germany

Abstract.  Abstract. We have performed comprehensive investigation on the static and dynamic behaviors in detached recombining plasmas in the linear divertor plasma simulator, NAGDIS-II. For the stationary plasma detachment, the transition from electron-ion recombination (EIR) to molecular activated recombination (MAR) has been observed by injecting hydrogen gas to high density He plasmas. The particle loss rate due to MAR is found to be comparable to that of EIR. We have also performed experiments on injection of a plasma heat pulse produced by rf heating to the detached recombining He plasma to demonstrate the dynamic behavior of the volumetric plasma recombination. Negative spikes in Balmer series line emissions were observed similar to the so called negative ELM observed in tokamak divertors, which were analyzed with collisional-radiative model in detail. Rapid increase of the ion flux to the target plate was observed associated with the re-ionization of the highly excited atoms generated by EIR.

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