AC loss study by AC susceptibility measurement in a commercial Bi:2223/Ag tape prepared by the CTFF method: H \parallel c axis and short specimen

Abstract

The effect of temperature, field amplitude, frequency and orientation of the field on AC losses in a commercial Bi:2223/Ag tape prepared by the continuous filling and forming (CTFF) method has been investigated. The measurements were performed using an AC susceptometer. The experimental results show that the losses depend on field amplitude, temperature, DC field, orientation of the sample and strongly on frequency. Due to the strong dependence of AC losses on frequency, measurements were pursued at several frequencies between 20 Hz and 10 kHz at various temperatures (10, 20, 30 and 77 K). The strong frequency dependence at these low temperatures is attributed to eddy current losses and/or inter-filamentary coupling losses. At higher temperatures and low frequencies, the main contribution to AC losses comes from hysteresis losses due to the flux entry into and exit from the superconducting tape during the up and down swings of the magnetic field. We have calculated coupling losses as a function of frequency and temperature-dependent time constant. Experimental data are analyzed by comparing them with the calculated curves. From the DC field dependence of the AC susceptibility, we obtained the irreversibility line.

AC losses in superconductors shielded by a normal metal or another superconductor

“…The losses per cycle therefore decrease weaker at higher frequencies. Some measurements indicate this [21][22][23][24][25][26]. Our results are obtained by the analogy with the induced currents in normal metals.…”

Effect of dc field on ac-loss peak in a commercial Bi:2223/Ag tape

“…The fitting parameters of H *m0 = 110 Oe, n = 0.25, p = 2.2, T cm = 108 K gives quite good results to compare the experimental and calculated curves. Since we have kept the frequency fixed at low enough value (20 Hz), we neglected the contribution of eddy current and coupling loss here which is discussed in references [23,24]. TUBITAK-TBAG is gratefully knowledge for supporting the current study under grant contract no.…”

“…In addition, many researchers have studied analyzing the parameters playing the role of the ac losses of BSCCO/ Ag tapes [14][15][16][17][18][19][20][21][22][23][24]. Exploration of the parameters playing roles in the loss mechanisms can be useful in order to determine the optimum operating conditions.…”

“…Exploration of the parameters playing roles in the loss mechanisms can be useful in order to determine the optimum operating conditions. Çelebi et al have investigated the effect of frequency, field amplitude, and orientation of the field (namely parallel [23] and perpendicular [24] to the wide face of the tape) on ac losses in a commercial Bi:2223/Ag tape.…”

AC susceptibility as a characterization tool for coated conductor tapes

“…As one can see in this section magnetization data can be used to evaluate the AC susceptibility parts that comprise information about AC loss in the imaginary part. Therefore a measurement of AC susceptibility also automatically provides the value of AC loss in a sample exposed to an AC magnetic field [23,[30][31][32][33][34]. Figure 2 illustrates this correspondence and there is another detail worth noting: χ″ can be interpreted as the 'efficiency' of converting into heat the energy delivered to the sample by the source of the applied field, that in turn is proportional toB .…”