Limits...
Hysteresis in Transport Critical-Current Measurements of Oxide Superconductors

View Article: PubMed Central - PubMed

ABSTRACT

We have investigated magnetic hysteresis in transport critical-current (Ic) measurements of Ag-matrix (Bi,Pb)2Sr2Ca2Cu3O10–x (Bi-2223) and AgMg-matrix Bi2Sr2CaCu2O8+x (Bi-2212) tapes. The effect of magnetic hysteresis on the measured critical current of high temperature superconductors is a very important consideration for every measurement procedure that involves more than one sweep of magnetic field, changes in field angle, or changes in temperature at a given field. The existence of this hysteresis is well known; however, the implications for a measurement standard or interlaboratory comparisons are often ignored and the measurements are often made in the most expedient way. A key finding is that Ic at a given angle, determined by sweeping the angles in a given magnetic field, can be 17 % different from the Ic determined after the angle was fixed in zero field and the magnet then ramped to the given field. Which value is correct is addressed in the context that the proper sequence of measurement conditions reflects the application conditions. The hysteresis in angle-sweep and temperature-sweep data is related to the hysteresis observed when the field is swept up and down at constant angle and temperature. The necessity of heating a specimen to near its transition temperature to reset it to an initial state between measurements at different angles and temperatures is discussed.

No MeSH data available.


Ic at 0.1 µV/cm versus magnetic field (initial/virgin curves) for the Bi-2223 specimen for various temperatures and angles: (a) 90°, (b) 0°.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4862823&req=5

f10-j64goo: Ic at 0.1 µV/cm versus magnetic field (initial/virgin curves) for the Bi-2223 specimen for various temperatures and angles: (a) 90°, (b) 0°.

Mentions: Temperature cross sections of the Bi-2223 specimen’s critical surface are shown in Fig. 10 at 90° and 0°. The curves shown were taken with increasing field. The specimen was flash heated before each curve. For each angle, the curves at different temperatures are similar. The curves at different angles differ. The x-axis is logarithmic to better illustrate the dependence over a wide range of magnetic fields. If the x-axis were linear, these cross sections of the critical surface would appear quite different.


Hysteresis in Transport Critical-Current Measurements of Oxide Superconductors
Ic at 0.1 µV/cm versus magnetic field (initial/virgin curves) for the Bi-2223 specimen for various temperatures and angles: (a) 90°, (b) 0°.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4862823&req=5

f10-j64goo: Ic at 0.1 µV/cm versus magnetic field (initial/virgin curves) for the Bi-2223 specimen for various temperatures and angles: (a) 90°, (b) 0°.
Mentions: Temperature cross sections of the Bi-2223 specimen’s critical surface are shown in Fig. 10 at 90° and 0°. The curves shown were taken with increasing field. The specimen was flash heated before each curve. For each angle, the curves at different temperatures are similar. The curves at different angles differ. The x-axis is logarithmic to better illustrate the dependence over a wide range of magnetic fields. If the x-axis were linear, these cross sections of the critical surface would appear quite different.

View Article: PubMed Central - PubMed

ABSTRACT

We have investigated magnetic hysteresis in transport critical-current (Ic) measurements of Ag-matrix (Bi,Pb)2Sr2Ca2Cu3O10–x (Bi-2223) and AgMg-matrix Bi2Sr2CaCu2O8+x (Bi-2212) tapes. The effect of magnetic hysteresis on the measured critical current of high temperature superconductors is a very important consideration for every measurement procedure that involves more than one sweep of magnetic field, changes in field angle, or changes in temperature at a given field. The existence of this hysteresis is well known; however, the implications for a measurement standard or interlaboratory comparisons are often ignored and the measurements are often made in the most expedient way. A key finding is that Ic at a given angle, determined by sweeping the angles in a given magnetic field, can be 17 % different from the Ic determined after the angle was fixed in zero field and the magnet then ramped to the given field. Which value is correct is addressed in the context that the proper sequence of measurement conditions reflects the application conditions. The hysteresis in angle-sweep and temperature-sweep data is related to the hysteresis observed when the field is swept up and down at constant angle and temperature. The necessity of heating a specimen to near its transition temperature to reset it to an initial state between measurements at different angles and temperatures is discussed.

No MeSH data available.