The limitation of an explosive instability of two counter-streaming electron beams

Second-order perturbation calculation shows that an explosive instability of three resonantly interacting waves is limited and converted into a multi-periodic process by non-linear terms of the same order as those that destabilize the waves in the first-order approximation.     

Upconversion of whistler waves by gyrating ion beams in a plasma

A gyrating ion beam, with a ring-shaped distribution in velocity, supports negative energy beam modes near the harmonics of beam gyro-frequency. An investigation of the non-linear interaction of high-frequency whistler waves with the negative energy beam cyclotron mode is made. A non-linear dispersion relation is derived for the coupled modes. It is shown that a gyrating ion-beam frequency upconverts the whistler waves separated by harmonics of beam gyro-frequency. The expression for the growth rate of whistler mode waves has been derived. In Case 1, a high-amplitude whistler wave decays into two lower frequency waves, called a low-frequency mode and a side band of frequency lower than that of pump wave. In Case 2 a high-amplitude whistler wave decays into two lower frequency daughter waves, called the low-frequency mode and whistler waves. Generation mechanism of these waves has application in space and laboratory plasmas.     

Filamentation instability in two counter-streaming laser plasmas

The filamentation instability was observed in the interaction of two counter-streaming laser ablated plasma flows,which were supersonic, collisionless, and also closely relevant to astrophysical conditions. The plasma flows were created by irradiating a pair of oppositely standing plastic(CH) foils with 1ns-pulsed laser beams of total energy of 1.7 k J in two laser spots. With characteristics diagnosed in experiments, the calculated features of Weibel-type filaments are in good agreement with measurements.     

Direct acceleration of electrons using two crossed Laguerre--Gaussian laser beams in vacuum

The basic physical characteristics of electrons accelerated by two linearly polarized and circularly symmetric crossed Laguerre--Gaussian (LG) laser beams with equal frequency and amplitude in vacuum are studied in detail. The condition, under which electrons can be accelerated effectively, and the energy gain are discussed.     

Instability of spatially separated plasma beams. III

Two-stream instability in spatially separated plasma beams having a finite thickness are investigated in the quasihydrodynamic approximation. It is shown that in beams having a finite thickness the instability domain is bounded for both low and high drift velocities. The minimum drift velocity at which instability develops may be less than the corresponding magnitude in semibounded beams. With decreasing thickness of the layers, the maximum growth rate of the amplified waves falls off. An influence of a dielectric interlayer between beams on the character of the instability is revealed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 15, No. 4, pp. 521–527, April, 1972.     

Bremsstrahlung production by colliding beams of protons and electrons

The differential cross section of bremsstrahlung emitted in the head-on collision of beams of energetic protons and electrons is calculated in the laboratory frame. The angular distribution of the photons is more isotropic than in the common bremsstrahlung production on stationary target atoms. The total cross section is determined by integration over the photon angles which are allowed kinematically.     

Experimental study of intense screw beams with trapped electrons

The velocity spread and average oscillatory energy of intense screw beams of gyrotrons are experimentally studied in the presence of electrons reflected from a magnetic mirror and captured in an adiabatic trap. The results of the experiments indicate a significant influence of trapped electrons on the parameters of beams, especially in systems forming quasilaminar beams. Modifications of magnetron-injector guns are considered in which a certain reduction of the influence of reflected electrons is reached.Institute of Applied Physics, Russian Academy of Science, Nizhny Novgorod. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 38, No. 8, pp. 860–869, August, 1995.     

Stability of high-current beams of relativistic electrons in cyclic systems

Stability conditions of high-current thin beams of relativistic electrons against excitation of long-wave oscillations in a stellatron and modified betatron have been investigated theoretically. The influence of self electric and magnetic fields obtained from electron beam delayed potentials has been taken into consideration. The correspondent dispersion relation has been found. The electron beam of the modified betatron has been shown to be always unstable against excitation of the oscillations considered. Necessary and sufficient conditions for the elec-tron beam confinement in a stellatron have been found.     

Contribution to the theory of helical beams with trapped electrons

Institute of Applied Physics, Academy of Sciences of the USSR. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 33, No. 12, pp. 1406–1411, December, 1990.     

2D scattering of unpolarized beams of electrons by charged nanomagnets

2D spin-dependent scattering of slow unpolarized beams of electrons by charged nanomagnets is analyzed in the Born approximation. The obtained scattering lengths are larger than those from the neutral nanomagnets approximately by one order. It is shown that for particular parameters of the system it is possible to polarize completely the scattered electrons in a narrow range of scattering angles. The most suitable system for realization of these effects is 2D Si electron gas with immersed nanomagnets.     

Attosecond-correlated dynamics of two electrons in argon

In this work we explored strong field-induced decay of doubly excited transient Coulomb complex Ar ^?? → Ar ²⁺ + 2e. We measured the correlated two-electron emission as a function of carrier envelop phase (CEP) of 6 fs pulses in the non-sequential double ionization (NSDI) of argon. Classical model calculations suggest that the intermediate doubly excited Coulomb complex loses memory of its formation dynamics. We estimated the ionization time difference between the two electrons from NSDI of argon and it is 200 ± 100 as (N Camus et al, Phys. Rev. Lett. 108, 073003 (2012)).     

Interference patterns of two non-diffracting beams

The interference field of two non-diffracting beams is derived analytically. We arrange the experiments with an axicon illuminated by two monochromatic oblique beams. Based on the diffraction properties of an axicon in the case of oblique illumination, the intensity distribution of interference pattern was calculated, and it was demonstrated to be the superposition of zero-order Bessel functions. The locus of interference fringes is also analyzed to be hyperbola according to the zero formula of zero-order Bessel function. The experimental results are verified the numerical simulation.     

Runaway electrons and Generation of high-power subnanosecond electron beams in dense gases

Works on the physics of electron runaway in gases, developing a new understanding of formation of runaway electron beams in gas discharge, are reviewed. Results of experiments with atmospheric-pressure gas-filled diodes, in which subnanosecond electron beams with a record current amplitude were obtained, are reported. The properties of volume nanosecond discharge, allowing to obtain such beams, are analyzed.     

Gravitational force between two electrons in superconductors

The attractive gravitational force between two electrons in superconductors is deduced from the Eddington–Dirac large number relation, together with Beck and Mackey electromagnetic model of vacuum energy in superconductors. This force is estimated to be weaker than the gravitational attraction between two electrons in the vacuum.     

Dynamical localization of two electrons in triple-quantum-dot shuttles

The dynamical localization phenomena in two-electron quantum-dot shuttles driven by an ac field have been investigated and analyzed by the Floquet theory. The dynamical localization occurs near the anti-crossings in Floquet eigenenergy spectrum. The oscillation of the quantum-dot shuttles may increase the possibility of the dynamical localization. Especially, even if the two electrons are initialized in two neighbor dots, they can be localized there for appropriate intensity of the driven field. The studies may help the understanding of dynamical localization in electron shuttles and expand the application potential of nanoelectromechanical devices.