  AC losses of YBCO coated conductors are investigated by calculation and
experiment for the higher frequency regime. Previous research using YBCO film
deposited onto single crystal substrates demonstrated the effectiveness of
filamentary subdivision as a technique for AC loss reduction. As a result of
these studies the idea of subdividing YBCO coated conductors (both YBCO,
overlayer, and even underlayer) into such stripes suggested itself. The
suggestion was implemented by burning grooves into samples of coated conductor
using laser micromachining. Various machining parameters were investigated, and
the striping and slicing characteristics are presented. Loss measurements were
performed on unstriped as well as striped samples by the pick-up coil technique
at frequencies of from 50-200 Hz at field sweep amplitudes of up to 150 mT. The
effect of soft ferromagnetic Fe shielding was also investigated. The results of
the experiments form a starting point for a more general study of reduced loss
coated conductor design (including hysteretic, coupling, normal eddy current,
and transport losses) projected into higher ranges of frequency and field sweep
amplitude with transformer and all cryogenic motor/generator applications in
mind.
