Design and installation of the closed helical divertor in LHD

作者：Masuzaki S^*; Shoji M; Tokitani M; Murase T; Kobayashi M; Morisaki T; Yonezu H; Sakamoto R; Yamada H; Komori A

来源：Fusion Engineering and Design, 2010, 85(6): 940-945.

DOI：10.1016/j.fusengdes.2010.08.048

• LHD heliotron
• Closed divertor
• EIRENE code
• Hydrogen recycling

Neutral particle behavior in the Large Helical Device heliotron has been investigated to conduct the effective particle control using the intrinsic helical divertor. It was revealed that the torus in-out asymmetry observed in the neutral pressure distribution depended on the divertor particle flux distribution, and thus, on the operational magnetic configuration. It was also revealed that the neutral pressure in the vacuum vessel in LHD was below 0.1 Pa. Degradation of the plasma confinement with increasing of the neutral pressure was observed, and that suggested the effective particle control is necessary for the sustaining of long discharge with high performance plasma and the further improvement of the confinement. The modification of the open helical divertor to the closed one was investigated for the particle control using helical divertor by using EIRENE code. Results of the calculation showed that proper rearrangement of divertor plates and additional components, such as dome structure make the neutral particles to be compressed well in the divertor region, and effective divertor pumping to be possible. Based on the simulation and experimental results, design of the closed helical divertor was completed and it will be partially installed in the Large Helical Device before the experimental campaign in 2010.

• 出版日期2010-11