Investigation of Pulse Glow Discharge Excitation Modes in N2 in a Hollow Cylindrical Combined Cathode

Electric discharge excitation modes and N2 pressure range for a stable formation and maintaining of pulse glow discharge plasma in a hollow combined cathode have been investigated. It has been found that both of these parameters are influenced by the constructive peculiarities of the cathode. It has been established experimentally that the value of N2 breakdown voltage for the studied construction of the cathode within the range of 50-250 Pa does not exceed -700 V

Andreev reflection in bosonic condensates

We study the bosonic analog of Andreev reflection at a normal-superfluid interface where the superfluid is a boson condensate. We model the normal region as a zone where nonlinear effects can be neglected. Against the background of a decaying condensate, we identify a novel contribution to the current of reflected atoms. The group velocity of this Andreev reflected component differs from that of the normally reflected one. For a three-dimensional planar or two-dimensional linear interface Andreev reflection is neither specular nor conjugate.Comment: 5 pages, 3 figures. Text revise

Investigation of Peculiarities of the Discharge Excitation with Hollow Cathode Effect in N2 in a Tube Electrode

The influence of some constructive discharge system elements on the electric excitation modes and stable maintaining of pulse glow discharge plasma in N2 in a hollow tube cathode has been investigated. The following discharge system changes have been performed: the position of a hollow electrode-cathode in the dielectric tube-holder; the method of plasma forming gas feeding to the discharge area; the distance between the electrode-cathode and counter-electrode (grounded anode). The investigation has been carried out within 50–700 Pa N2 pressure range. The obtained results may be used in the design of gas discharge systems with hollow cathode effect

Loss of Andreev Backscattering in Superconducting Quantum Point Contacts

We study effects of magnetic field on the energy spectrum in a superconducting quantum point contact. The supercurrent induced by the magnetic field leads to intermode transitions between the electron waves that pass and do not pass through the constriction. The latter experience normal reflections which couple the states with opposite momenta inside the quantum channel and create a minigap in the energy spectrum that depends on the magnetic field

Focused Crossed Andreev Reflection

We consider non-local transport in a system with one superconducting and two normal metal terminals. Electron focusing by weak perpendicular magnetic fields is shown to tune the ratio between crossed Andreev reflection (CAR) and electron transfer (ET) in the non-local current response. Additionally, electron focusing facilitates non-local signals between normal metal contacts where the separation is as large as the mean free path rather than being limited by the coherence length of the superconductor. CAR and ET can be selectively enhanced by modulating the magnetic field

Tunable space-time crystal in room-temperature magnetodielectrics

We report the experimental realization of a space-time crystal with tunable periodicity in time and space in the magnon Bose-Einstein Condensate (BEC), formed in a room-temperature Yttrium Iron Garnet (YIG) film by radio-frequency space-homogeneous magnetic field. The magnon BEC is prepared to have a well defined frequency and non-zero wavevector. We demonstrate how the crystalline "density" as well as the time and space textures of the resulting crystal may be tuned by varying the experimental parameters: external static magnetic field, temperature, thickness of the YIG film and power of the radio-frequency field. The proposed space-time crystals provide a new dimension for exploring dynamical phases of matter and can serve as a model nonlinear Floquet system, that brings in touch the rich fields of classical nonlinear waves, magnonics and periodically driven systems