Frequency dependence of hysteresis loss in YBCO tapes

We measured the frequency dependence of hysteresis loss in non-striated and striated YBCO coated conductors in the frequency range from 1 mHz up to 350 mHz at 77 K. At these frequencies the coupling losses in YBCO coated conductors do not exist and in filamentary YBCO tapes they can be practically neglected. The dominant loss component is the hysteresis loss. We have found that for magnetic fields above the full penetration field the hysteresis loss increases with increasing frequency and this dependence can be described by a power law function. For magnetic fields below the penetration field the hysteresis loss decreases with frequency. This behaviour supports the previous theoretical results indicating that the field dividing the behaviour of hysteresis losses versus frequency is the penetration field. The experiments with YBCO samples on non-metallic substrate at frequencies up to 600 Hz show that the dependence of hysteresis losses measured at millihertz frequencies can be extrapolated to higher frequencies of the order of 100 Hz. We propose a simple procedure to separate the hysteresis losses from the total measured losses based on the measurement of the frequency dependence of losses at low frequencies. Taking into account the frequency dependence of hysteresis losses we can considerably reduce the errors in the separation of hysteresis losses from the total measured losses