Stability test results on the aluminum stabilized superconductor for the helical coils of LHD

Yanagi, N.; Satow, T.; Mito, T.; Imagawa, S.; Takahata, K.; Iwamoto, A.; Chikaraishi, H.; Yamaguchi, S.; Satoh, Shuichi; Motojima, O.; Noguchi, So; Ishiyama, Atsushi

doi:10.1109/77.783493

Cited by 11 publications

(4 citation statements)

References 8 publications

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“…Therefore, the current shifted to the stabilizer from the tail end of the normal zone, where the conductor recovered to the superconducting state. This phenomenon is called "traveling normal zone" [4]. The traveling normal zone moved through the taps V4 and V5, and disappeared in the upper part of the test coil where the magnetic field was lower than that of the test part.…”

Section: A Typical Waveforms Of Stability Test Resultsmentioning

confidence: 99%

“…A composite superconductor, which is used for the helical coils, consists of a NbTi/Cu Rutherford cable, a pure aluminum stabilizer and a copper sheath with electron beam welds. The conductor has rectangular shape with 12.5 mm 18.0 mm size, and Cu-oxide layer covers the outer surface of it [4]. The cross-sectional view of the LHD conductor is shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

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Cooling Stability Test of He II Cooled LHD Conductor (2)—Experimental Results

Ohya¹,

Higuchi²,

Shirai³

et al. 2004

IEEE Trans. Appl. Supercond.

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Cooling stability tests of the Large Helical Device (LHD) conductor immersed in pressurized He I and He II were carried out. A small test coil wound and short-circuited with a LHD conductor on a stainless steel bobbin was used. The test coil was set coaxially in the center of a superconducting magnet (field magnet), which supplies a certain magnetic field to the test conductor. A large current was supplied to the test coil conductor by use of a transformer effect, that is, the test coil current was induced by increasing the current of the field magnet. Stability tests of the LHD conductor at a certain pulse heat input were performed for the magnetic flux densities from 1.2 T to 6.8 T and the bulk liquid He temperatures from 2.0 K to 4.2 K at atmospheric pressure. Experimental results can be classified into three groups. The normal zone arose only around the heater and disappeared after the heat pulse (Group I). The normal zone moved to only one side direction and disappeared (Group II). The normal zone spread on both sides and the conductor current decreased greatly (Group III). The maximum conductor current without a quench at the pulse heat input increased greatly by shifting to He II regime from He I regime. The advances of the He II cooling on the stability of the LHD conductor were confirmed.Index Terms-Aluminum stabilized superconductor, cryogenic stability, superfluid helium.

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Section: A Typical Waveforms Of Stability Test Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cooling Stability Test of He II Cooled LHD Conductor (2)—Experimental Results

Ohya¹,

Higuchi²,

Shirai³

et al. 2004

IEEE Trans. Appl. Supercond.

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“…The STARS conductor with internal electrical insulation has been designed firstly as shown in figure 1, which gives almost a similar layout as that without insulation [9], having an outer dimension of 22.5 mm by 10 mm. Note that the cross-sectional area of this choice would be the same as that of the aluminumstabilized NbTi/Cu conductor used in the LHD helical coils with 18 mm by 12.5 mm [14]. Two sample conductors having 1-m and 3-m lengths were fabricated with internal electrical insulation.…”

Section: Stars Conductor With Internal Electrical Insulationmentioning

confidence: 99%

Stable operation characteristics and perspectives of the large-current HTS STARS conductor

Yanagi,

Narushima,

Onodera

et al. 2023

J. Phys.: Conf. Ser.

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The High-Temperature Superconducting (HTS) magnet option has been explored for fusion reactors as well as for next-generation fusion experimental devices. The Stacked Tapes Assembled in Rigid Structure (STARS) conductor uses HTS tapes with simple stacking without twisting and transposition. A practically applicable STARS conductor is presently being developed with an operating current of 18 kA at 20 K temperature and ~15 T magnetic field. The conductor is required to have a high current density of 80 A/mm2. For the second stage of the conductor development, internal electrical insulation is applied between the copper stabilizer casing and the outer stainless-steel jacket, and a 6-m conductor sample was fabricated in a solenoid coil shape with a 600-mm diameter and three turns. The coiled sample was tested in 8 T, 20 K using a facility equipped with a maximum 13-T, 700-mm bore solenoid coil. Excitation up to the rated current of 18 kA was successfully attained with stable operation. The characteristics of the conductor observed during the excitation test are discussed.

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“…In 2D simulation, however, it is impossible to deal with the Hall current generation exactly because it is anisotropic. Therefore, the equivalent resistivity caused by the Hall current generation is obtained from the experimental data [2] as shown in Fig. 4.…”

Section: Hall Current Generation In 2d Simulationmentioning

confidence: 99%