AC loss measurement of 46 kA-13T Nb/sub 3/Sn conductor for ITER

Takahashi, Yoshikazu; Matsui, K.; Nishii, Kenji; Koizumi, N.; Nunoya, Y.; Isono, T.; Ando, T.; Tsuji, Hiroshi; Murase, S.; Shimamoto, S.

doi:10.1109/77.920071

Cited by 34 publications

(20 citation statements)

References 8 publications

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“…The hysteresis loss in superconducting coils has actually been measured by extrapolating several pulse or cyclic excitation data sets with different sweep rates or frequencies. However, previous studies using other coils with CICC suggest that the extrapolated loss obtained by the above-mentioned method was much larger than the hysteresis loss estimated using the magnetic hysteresis of the strands or theoretical calculations [5,6]. Our measurements show similar behavior.…”

Section: Introductionsupporting

confidence: 66%

Hysteresis Loss in Poloidal Coils of the Large Helical Device

Takahata

Chikaraishi

Mito

et al. 2011

Plasma and Fusion Research

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Hysteresis loss in poloidal coils of the Large Helical Device (LHD) has been measured during single-pulse operation. The superconductors of the coils are Nb-Ti cable-in-conduit conductors (CICC) cooled by forcedflow supercritical helium. The loss was measured by monitoring the enthalpy increase of the helium coolant between the inlet and outlet. Although the hysteresis loss was extracted by extrapolating several data sets from pulse excitations with different sweep rates, the extrapolated loss was much larger than the estimation using the magnetic hysteresis of the conductor. The anomalous increase in the loss is likely due to inter-strand coupling loss with long time constants from the order of 10 to 1000 s. The calculations show that the additional coupling loss behaves like a hysteresis loss.

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Section: Introductionsupporting

confidence: 66%

Hysteresis Loss in Poloidal Coils of the Large Helical Device

Takahata

Chikaraishi

Mito

et al. 2011

Plasma and Fusion Research

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“…AC losses of a CICC can be expressed by the following equation [5]. (1) where is the mass-flow rate at the outlet (g/s), , enthalpy at outlet (J/g), and , initial enthalpy at outlet (J/g).…”

Section: Experimental Setup and Measurement Methodsmentioning

confidence: 99%

AC Loss Characteristics of the KSTAR CSMC Estimated by Pulse Test

Lee

Chu

Chung

et al. 2006

IEEE Trans. Appl. Supercond.

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The KSTAR Central Solenoid Model Coils (CSMC), which are in the form of split coils with same dimension, have been tested. The CSMC were successfully charged up to 20 kA and down to zero with different ramp rates. Various pulse waveforms were applied to the CSMC to analyse the AC-loss characteristics of the coils. The measurement method was a gas-flow calorimetry. In this work, two types of waveforms, the DC-biased sinusoidal wave ( = 2, 4 kA;

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“…Several parameters such as the current wave form, the AC losses, the inlet boundary condition, the magnetic field distribution along the CH5 length, and the KSTAR superconducting strand were modeled to calculate the thermo-hydraulics about the unipolar operation by using several external routines in the code. The AC losses were calculated with taking into account of the coupling loss and the hysteresis loss of superconducting strand including the eddy current loss of jacket, which had been dominantly influenced at low current operations [8]. The coupling constant time was 64 ms in this calculation.…”

Section: A Boundary Conditions For Aimulationmentioning

confidence: 99%

Analysis of the Reversal Flow Phenomenon of Supercritical Helium Due to AC Losses in the KSTAR PF Magnets at the Low Current

Lee

Park²,

Chu³

et al. 2011

IEEE Trans. Appl. Supercond.

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Superconducting magnets of the Korea Superconducting Tokamak Advanced Research (KSTAR) are cooled by supercritical helium with 4.5 K, which was supplied and recovered by the 9 kW of the Helium Refrigerator System (HRS). While current is being charged, the supercritical helium expands to both side of the helium inlet and the outlet of the magnets due to the generated AC losses. To maintain the pressure gradient, both the supply and the return pressures of the HRS are increased at the same time and the differential pressure of the HRS was reduced after the event. However, the pressure rising in the magnets may block the helium flow or create reversal flow of the helium. During unipolar experiment of PF1 magnet up to 2 kA with 1 kA/s of ramp-up rate, the mass flow rate was decreased at the PF1 cooling tube (manifold) in the helium distribution system (HDS), whereas the pressure is increased and the temperature is to be increased or decreased according to compression and expansion of the heated helium in the magnets. For the bipolar experiment of PF1 up to 2 kA with 1 kA/s ramp-up rate and 2 kA/s ramp-down rate, the conditions in the helium flow were drastically changed, especially the mass flow rate was measured to be maintained at zero for a few second (more than 4 s). This behavior could decisively affect the cryogenic stabilities in the magnet, and may impose a major limit on the long pulse operation of KSTAR. In this paper, we investigated this behavior and analysed by using 1-dimentional thermo-hydraulic code, GANDALF.Index Terms-CICC, KSTAR, reversal flow, thermo-hydraulic phenomenon of supercritical helium.

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AC loss measurement of 46 kA-13T Nb/sub 3/Sn conductor for ITER

Cited by 34 publications

References 8 publications

Hysteresis Loss in Poloidal Coils of the Large Helical Device

Hysteresis Loss in Poloidal Coils of the Large Helical Device

AC Loss Characteristics of the KSTAR CSMC Estimated by Pulse Test

Analysis of the Reversal Flow Phenomenon of Supercritical Helium Due to AC Losses in the KSTAR PF Magnets at the Low Current

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