Regensburg 2000 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe

TT: Tiefe Temperaturen

TT 22: Postersitzung III: Supraleitende Anwendungen (1-4) Massive HTSL, Bandleiter, Filme (5-26), Transport in HTSL (27-30), Elektronenstruktur in Supraleitern (31-43), Borkarbide (44-50), Quantenphasen- und Metall-Isolator-Überg
änge (51-69)

TT 22.24: Poster

Donnerstag, 30. März 2000, 14:00–17:30, A

Rf field dependence of the surface impedance of YBCO - time and frequency domain — •Kai Numssen¹, Ermile Gaganidze², and Juergen Halbritter² — ¹TU Muenchen, James-Frank Str. 1, D-85747 Garching, Germany — ²Forschungszentrum Karlsruhe, IMF 1, Postfach 3640, D-76021 Karlsruhe, Germany

The application of HT_c-superconducting wafers in rf devices requires a profound knowledge of the rf field dependent surface impedance Z_s=R_s+iX_s. It has been found that the mechanisms yielding a nonlinear behaviour Z_s(H) can best be classified on the basis of the ratio r=dX_s/dR_s. In contrast to R_s(H) and X_s(H), the determination of this quantity is independent of geometric factors and of a measurement set-up.

We present a pulse measurement technique which combines frequency and time domain. The parameter r is directly derived by fitting nonlinear resonator response curves to the measurement data. Moreover, by the examination of the excess transmission at the beginning of the pulse response this measurement technique gives hints on the dynamics of the underlying nonlinear mechanisms.

From the power dependence δ Z(H_rf) and observed r-values, r= 1..10, we conclude, that Josephson fluxons in weak links play the most important role.