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Magnetization vs. applied field measurements ( -loops) were taken on YBCO thin films with filaments patterned into them. The YBCO was deposited onto LaAlO 3 substrates using PLD, and the filaments were formed by laser ablation.-loops were taken at 4.2 K in fields up to 9 T using a vibrating sample magnetometer technique, the field applied perpendicular to the film width, . The losses were seen to be greatly reduced by filament width reductions following the standard expression 10. The penetration field was also well described by the standard "high field" expression = (0 4 ) ln( + 1), where is the film thickness. The regimes of applicability of the loss expression were investigated, in particular near . A more general form of the loss equation was obtained and compared with the high-field approximation. The result was that although still increased in proportion to , the rate of increase decreased as approached .Index Terms-AC loss, hysteretic loss, penetration field, YBCO.

Abstract-Many future military systems will depend heavily on high electrical power input ranging from 100's kilowatts up to the multimegawatt level. These weapon systems include electromagnetic launch applications as well as electrically driven directed energy weapons (DEW), such as high power microwaves and solid state lasers. These power generation subsystems must often be packaged using limited space and strict weight limits on either ground mobile or airborne platforms. Superconducting generators made of high temperature superconductors (HTS) will enable megawatt-class airborne power systems that are lightweight and compact. Also discussed briefly are new advances in HTS conductors and refrigeration systems furthering the development of HTS power systems.

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