Fig. 3

Volumetric flow of helium versus heater power describing the filter efficiencies: (a) two characteristic regions laminar and turbulent are shown for YBCO-123 filter and presented as the three measured series—blue triangles, red squares, and yellow stars. (b) comparison of laminar regions for classical and superconducting entropy filters. The slopes define individual efficiencies: red circles and yellow triangles are taken from¹⁵ together with the data from Nakai’s paper—the dashed line (the average of the values from¹³). Red squares, blue triangles, red squares, and yellow stars represent three series of YBCO-123 filter.