Analysis of the normal transition event of the LHD helical coils

Author

Yanagi, N. ; Imagawa, S. ; Mito, T. ; Iwamoto, A. ; Chikaraishi, H. ; Hamaguchi, S. ; Nishimura, A. ; Satow, T. ; Nakamura, Y. ; Satoh, S. ; Motojima, O. ; Gavrilin, A.V.

Author_Institution

Nat. Inst. for Fusion Sci., Toki, Japan

Volume

10

Issue

1

fYear

2000

fDate

3/1/2000 12:00:00 AM

Firstpage

610

Lastpage

613

Abstract

Normal transitions and a subsequent quench were experienced with the pool-cooled helical coils of the Large Helical Device (LHD) during its excitation test. Although the initiated normal zone once started to recover, a disruptive transverse propagation followed and triggered an emergency discharging program. The cryogenic stability of the composite-type superconductor has been studied by sample experiments as well as by numerical calculations. Due to the rather long magnetic diffusion time constant in the pure Al stabilizer, transient stability of the conductor seems to play an important role for driving finite propagation of a normal zone. The cause of the final quench is also discussed from the viewpoint of cooling deterioration due to a possible accumulation of He bubbles.

Keywords

Tokamak devices; fusion reactor design; superconducting coils; superconducting magnets; Al; Al stabilizer; He; He bubbles; LHD; Large Helical Device; cryogenic stability; helical coils; magnetic diffusion time constant; normal transition; quench; transverse propagation; Conductors; Cooling; Hydrogen; Indium tin oxide; Plasma devices; Superconducting coils; Testing; Toroidal magnetic fields; Voltage;

fLanguage

English

Journal_Title

Applied Superconductivity, IEEE Transactions on

Publisher

ieee

ISSN

1051-8223

Type

jour

DOI

10.1109/77.828308

Filename

828308