Long HTS Tapes With High In-Field Performance Manufactured via Multibeam PLD With “Dynamic” Drum Concept

Alternative concepts based on drum design and reel-to-reel design were studied in the course of the development of industrial technology of long (up to 600 m) YBCO coated tapes. According to our previous route we investigated double disordered YBCO layers deposited by using extrinsic precipitations as well as intrinsic precipitations and structural defects. These superimposing of the nano-defect and inhomogeneities resulted in very high critical currents optimized for high-field operation. The HTS layers in our experiments were deposited onto CrNi stainless steel substrates which were polished and buffered with an in-plane textured yttria-stabilized-zirconia layer, 1.2-2 μ m thick. Critical currents in 220 and 550 m long tapes were 20-30% lower compared to length of 20 m, but still representing champion current values for long tapes. Development of the process based on drum concept resulted in finding a relationship between the tape throughput and the wall thickness of the drum. A concept of light, dynamic drum with thin walls, reduced heat capacity, and radial elasticity was analyzed and employed in processing of long, up to 600 m YBCO coated tapes. Comparison between drum and reel-to-reel techniques is provided. Newest status in long tape processing is reported.