647 research outputs found
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
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