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TT: Tiefe Temperaturen
TT 2: Supraleitung in Hochfrequenz und Elektronik
TT 2.4: Talk
Monday, March 17, 1997, 11:00–11:15, F2
Nonlinear surface impedance in low and high Tc - superconductors — •J. Halbritter — IMF1, Forschungszentrum Karlsruhe
The degradation of the surface impedance Z = R + iX with rf power is a principle limit for rf measurements and applications. Such nonlinearities occur for normal conducting cavities by heating or electron loading. But superconductors show a much richer spectrum of causes for nonlinearities. The nonlinearities in the surface resistance δ R ∝ γ Hn and surface reactance δ X ∝ α Hn can be classified by the ratio r = δ X / δ R. This ratio in value, temperature or frequency dependence differs for the different mechanisms allowing a unique identification of those mechanisms. This identification is a prerequisit for an improved rf cavity design and improvement of superconducting materials.