Superconducting tunnel junction refrigerator based on phonon deficit effec

The work presented in this thesis is divided into two related areas. The first area of research is a study of superconductor-insulator-normal metal (SIN) or superconductor-insulator-superconductor ( SIS) tunnel junctions as cooling device. The efficiency of these refrigerators depends on the tunneling transparency of the insulating barrier. The second area of research is a study of the quantum action which permits to define quantum chaos in analogy to classical chaos.;We study the "phonon deficit effect" in a low temperature superconductor-insulator-normal metal and low temperature superconductor-insulator-low temperature superconductor tunnel junctions using kinetic equations which have been derived many years ago. The mechanism of the "phonon deficit effect" is based on the violation of the detailed balance of hole and electron quasiparticle distributions in superconductors under certain circumstances.;We propose a micro-refrigerator design with phonon filters which increases the efficiency of the microrefrigerator. As filter we chose superlattice filters (Bragg grating) to suppress emitted phonons by superconductor-insulator-superconductor tunnel junction and thus prevent heating of the solid. At the same time we permit phonons with frequencies in the absorption window to enter into superconductor-insulator-superconductor tunnel junction and be absorbed by electrons. We demonstrated theoretically that in some temperature region the phonon absorption exists over all frequencies in low temperature SIN tunnel junctions. Using Bragg grating filters increases the efficiency of SIS and SIN tunnel junction microrefrigerators.;The low temperature superconductors are effective below 30--40 K. There is no other kind of solid state micro-refrigerators working in the range of 30K to 150K. The recently discovered high temperature superconductors are possible candidates to this region. An expression of the tunnel current for the superconductor-insulator-normal metal tunnel junction is calculated in the framework of the bipolaron theory of superconductivity. The refrigeration processes in those materials in the framework of bipolaron theory of superconductivity are presented and discussed.;The second part of this thesis is devoted to the quantum action and quantum chaos theory developed recently by Professor Helmut Kroger with his coworkers. The existence of quantum action is supported by numerical analysis and results of different numerical methods show consistency. The presented quantum action permits to define and analyze the quantum chaos like its classical counterpart via Lyapunov exponents and Poincare sections.