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Configuration and calibration of pickup coils for measurement of ac loss in long superconductors
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10.1063/1.1766100
/content/aip/journal/jap/96/4/10.1063/1.1766100
http://aip.metastore.ingenta.com/content/aip/journal/jap/96/4/10.1063/1.1766100

Figures

Image of FIG. 1.
FIG. 1.

Scheme of single-turn (a), (b) and multipleturn (c) saddlelike pickup coils used to measure ac losses in long superconductors.

Image of FIG. 2.
FIG. 2.

Schematics of theoretical and practical configurations for the measurement of ac losses and magnetization, where (a) shows an external sinusoid field of amplitude generated by a source solenoid coil with a sinusoidal current of amplitude from a current source at a voltage . (b) indicates a change in the voltage by at the current source when a magnetic sample is introduced in ac field . It is noted that is generally many orders of magnitude greater than . (c) replaces the source coil with a simple coil; an ac current is now required to produce the same field from the current source at a voltage . In (d) the voltage change due to a magnetic sample is comparable to . It is noted, however, that the current required to generate an useful applied field with such a simple coil is often too high to be practical. (e) shows the practical solution of maintaining the source solenoid coil for field generation and using the simple coil as the pickup to measure the magnetic signal from the sample against a background inductive pickup of similar magnitude.

Image of FIG. 3.
FIG. 3.

Numerically calculated errors, , of estimating ac losses of tapes under perpendicular fields with Eq. (6) for single-turn coils of different width, . Different tape side ratios, (squares) and (circles), have been considered. The results correspond to saturation field (full symbols) and (open symbols).

Image of FIG. 4.
FIG. 4.

(a) Errors calculated for a tape of under perpendicular ac fields using coils of different dimensions and with (a) infinite number of turns , Eq. (9). The lines are the errors for a single-turn coil and the shaded areas in the basal plane are the configurations that give errors higher than . (b) Finite number of turns, , Eq. (8). Light gray and dark gray surfaces correspond to and , respectively. A reference plane at is plotted.

Image of FIG. 5.
FIG. 5.

Calculated errors estimated using Eq. (6) to obtain losses of tapes under parallel fields using single-turn pickup coils of different dimensions, . Different tape side ratios, (□) and (▵), have been considered. The results correspond to the saturation field (full symbols) and (open symbols).

Image of FIG. 6.
FIG. 6.

Calculated errors of the losses estimated using Eq. (11) for tapes under parallel fields using single-turn pickup coils of different dimensions, . The same symbols as in Fig. 4 have been used.

Image of FIG. 7.
FIG. 7.

(a) Calculated errors of the losses estimated using Eq. (9) for a tape of under parallel fields using pickup coils of infinite number of turns and different dimensions. The solid and dashed lines correspond to errors of 5% and , respectively. (b) Errors of using Eq. (8) for narrow coils as a function of . Different values of the applied parallel fields (full symbols) and (open symbols); and tape aspect ratios 30 (circles) and 10 (squares) have been considered.

Image of FIG. 8.
FIG. 8.

(a) Experimentally measured losses of the tape under perpendicular ac fields using a narrow planar coil (circles), a wide planar coil (triangles), and a solenoid coil of eight turns (line). The ratio between the losses measured with the one-turn coils and the eight-turn coil are plotted in (b).

Image of FIG. 9.
FIG. 9.

(a) Experimentally measured losses of the tape under parallel ac fields using a narrow planar coil (circles), a wide planar coil (triangles), and a solenoid coil of eight turns (line). The ratio between the losses measured with the one-turn coils and the eight-turn coil are plotted in (b).

Tables

Generic image for table
Table I.

Recommended pickup coil configurations for ac loss measurements.

Generic image for table
Table II.

Characteristics of conductor used in experimental trials

Generic image for table
Table III.

Experimental details for the tested pickup coils. in , in ; in .

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/content/aip/journal/jap/96/4/10.1063/1.1766100
2004-08-02
2014-04-17
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752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Configuration and calibration of pickup coils for measurement of ac loss in long superconductors
http://aip.metastore.ingenta.com/content/aip/journal/jap/96/4/10.1063/1.1766100
10.1063/1.1766100
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