High power failure of superconducting microwave filters: Investigation by means of thermal imaging

Abstract

We have investigated power handling of high-temperature superconducting microstrip filters employing highly sensitive thermal imaging. At low power, the images show small heating effects localized to areas with high current densities (ΔT<0.5 K), consistent with the known surface resistance and simulations of the current distribution. The breakdown at high-power levels, however, is always nucleated by a frequency independent local hot spot (T≳Tc). Scanning electron microscopy analysis of this area reveals a flaw in the superconducting material, presumably reducing the local critical current. The maximum power handling of these filters is, therefore, still open to improvement.

Direct imaging of hot spots in Bi2Sr2CaCu2O8+δ mesa terahertz sources

“…The strong temperature dependence arises from the energy transfer process 15 making a sensitive thermal probe of an object coated with this material. Previously, variations of this technique employing small concentrations of Eu-chelates dissolved in polymer films have been used to image the onset of dissipation in superconducting microwave filters 16 and in micro-bridges. 17 In this work, we use films of EuTFC directly sublimated onto the surface of Bi-2212 mesas, which significantly improves the sensitivity and reduces the image acquisition time (Fig.…”

Temperature dependent photoluminescence down to 4.2K in EuTFC

“…In practical use FMI has been applied in several reports for electronic failure analysis [3][4][5], failure in solar cell [6] and study of biologicals cells [7]. Heat generation in superconductors has been measured at temperatures down to 50 K [8][9][10]. Thermal imaging was also demonstrated in wind tunnel experiments at 110 K [11].…”

Microwave losses and structural properties of large-area YBa/sub 2/Cu/sub 3/O/sub 7/ films on r-cut sapphire buffered with [001]/(111) oriented CeO/sub 2/

“…The YBCO films were grown epitaxially on r-cut sapphire buffered with a Ce02 layer of mixed (001)/( 11 1) orientation. The surface of these films on sapphire is smooth and free of cracks and outgrowths, which among others (i) favors these films for applications which require high-quality patterning and (ii) might be an indication, that hot spots are less likely to develop at high powers [12,14]. The properties of the YBCO films are stable in time.…”