Losses in multifilamentary superconductors at low levels of excitation

Zenkevitch, V.B.; Romaniuk, A. S.

doi:10.1109/tmag.1977.1059368

Cited by 19 publications

(4 citation statements)

References 3 publications

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“…To measure hysteresis loss more accurately, a periodic field variation, such as a sinusoidal wave with DC offset, is better than a single pulse according to a theoretical circuit model [8]. Because the loss with long time constants can be eliminated by a periodic variation, the difference between the extrapolated and hysteresis losses may decrease.…”

Section: Resultsmentioning

confidence: 99%

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: Resultsmentioning

confidence: 99%

Hysteresis Loss in Poloidal Coils of the Large Helical Device

Takahata

Chikaraishi

Mito

et al. 2011

Plasma and Fusion Research

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“…Subtracting the eddy current loss occurring in the copper saddles from the measured loss, we estimate the time constant, , of the coupling currents in the joint. The details of the formulas in (1) are described in [5].…”

Section: B Experimental Results and Discussionmentioning

confidence: 99%

“…The coupling loss is estimated as follows, which is based on the theoretical analysis [5], (2) where , , , , and are the time step, the coupling loss per volume during to , the magnetic field at , the effective current at , the time at , and the coupling time constant respectively as shown in Fig. 9.…”

Section: Total Loss Calculationmentioning

confidence: 99%

AC Loss and Temperature Rise at CIC Conductor Joint in EF Coil of JT-60SA

Takao

Masuda

Mitsui

et al. 2010

IEEE Trans. Appl. Supercond.

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Japan and EU are promoting the project that the coils in JT-60 installed in Japan Atomic Energy Agency are changed to superconducting coils. We numerically and experimentally evaluate thermal stability of a conductor joint in the planning superconducting coil (EF coil). We measured an AC loss of the prototype joint, and estimated the coupling time constant. The AC loss at the EF coils joint segment was calculated based on the coupling time constant and the magnetic field distribution. Moreover, the temperature rise due to the AC loss was numerically derived. The calculation result showed that the temperature rise was small and the coil was enough stable.

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“…Therefore we assumed the coupling time constant as an parameter to investigate and compare the measured coupling losses. The coupling loss per unit volume per cycle is explained generally as follows [4,5]. we = A *~~H , ' Q * (1) where H, is the peak value of the external magnetic field and A* is a factor which is defined by the configuration of the conductor such as a cross-sectional shape and a cable twist pitch.…”

Section: B Assumption Of the Coupling Time Constantmentioning

confidence: 99%