Nonlinear amplification effects in a periodically perturbed period-doubling series resonance circuit

The influence of small near-resonant perturbations on the period-doubling b ifurcations in a nonlinear series resonance circuit has been investigated i n detail. The series resonance circuit contains ferroelectric triglycine su lfate (TGS) as nonlinear capacitor. If the temperature of the TGS-crystal i s below the Curie-temperature this dynamical system is a good experimental realization of a Duffing-like oscillator with double-well potential. The de pth of the double-well potential may be changed easily by temperature varia tion of the TGS-crystal. Variation of the amplitude of the driving voltage in the order of magnitude of the coercive field strength and the frequency of the driving voltage in the range of domain relaxation can be used to tun e the system towards period-doubling bifurcations. An additional near-reson ant perturbation has been introduced into the system by amplitude modulatio n of the driving voltage. The observed effects (small signal amplification, shift of the bifurcation point, multiple-side peaks around odd harmonics o f half the driving frequency) are compared to theoretically derived results . They are well understood on the basis of the center manifold analysis tak ing into account nonlinear effects in the normal form of the period-doublin g bifurcation.