Nonlinear dynamics of beta induced Alfv\'en eigenmode driven by energetic particles

Nonlinear saturation of beta induced Alfv\'en eigenmode, driven by slowing down energetic particles via transit resonance, is investigated by the nonlinear hybrid magnetohyrodynamic gyro-kinetic code (XHMGC). Saturation is characterized by frequency chirping and symmetry breaking between co- and counter-passing particles, which can be understood as the the evidence of resonance-detuning. The scaling of the saturation amplitude with the growth rate is also demonstrated to be consistent with radial resonance detuning due to the radial non-uniformity and mode structure

Profiling and variation of laser pulse parameters as a way to preserve the stability of self-injected bunches during excitation of a wakefield in plasma

The paper considers the excitation of a wakefield in a metal-density plasma using a chain of x-ray laser pulses. The profiling parameters and the necessary parameters of laser pulses for obtaining stable high-quality bunches are found. An essential problem is the destruction of self-injected bunches in the course of their motion. The results of the study are one of the ways to solve the problem of transverse betatron oscillations, which lead to the destruction of bunches.Comment: 5 pages, 12 figure

Control of Characteristics of Self-injected and Accelerated Electron Bunch in Plasma by Laser Pulse Shaping on Radius, Intensity and Shape

At the laser acceleration of self-injected electron bunch by plasma wakefield it is important to form bunch with small energy spread and small size. It has been shown that laser-pulse shaping on radius, intensity and shape controls characteristics of the self-injected electron bunch and provides at certain shaping small energy spread and small size of self-injected and accelerated electron bunch.Comment: 4 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:2001.01246, arXiv:2007.1298

Homogeneous Focusing Field for Short Relativistic Electron Bunches in Plasma

Plasma wake lens in which all short relativistic electron bunches of sequence are focused identically and uniformly is studied analytically and by numerical simulation. For two types of lenses necessary parameters of focused sequence of relativistic electron bunches are formulated. Verification of these parameters is performed by numerical simulation

Spectroscopy of doubly charmed baryons: Ξcc+\Xi_{cc}^{+} and Ξcc++\Xi_{cc}^{++}

Using the quark-diquark approximation in the framework of Buchm\" uller-Tye potential model, we investigate the spectroscopy of doubly charmed baryons: $\Xi_{cc}^{++}$ and $\Xi_{cc}^{+}$. Our results include the masses, parameters of radial wave functions of states with the different excitations of both diquark and light quark-diquark system. We calculate the values of fine and hyperfine splittings of these levels and discuss some new features, connected to the identity of heavy quarks, in the dynamics of hadronic and radiative transitions between the states of these baryons.Comment: 10 pages, Latex file, 1 fig, corrected some typo

Tornado model for a magnetised plasma

A new analytical model of axially-symmetric magnetic vortices with both a twisted fluid flow and a magnetic field is proposed. The exact solution for the three-dimensional structure of the fluid velocity and the magnetic field is obtained within the framework of the ideal magnetohydrodynamic equations for an incompressible fluid in a gravitational field. A quasi-stationary localised vortex arises when the radial flow that tends to concentrate vorticity in a narrow column around the axis of symmetry is balanced by the vertical vortex advection in the axial direction. The explicit expressions for the velocity and magnetic field components are obtained. The proposed analytic model may be used to parameterise the observed solar tornadoes and can provide a new indirect way for estimating magnetic twist from the observed azimuthal velocity profiles

Special case of sunset: reduction and epsilon-expansion

We consider two loop sunset diagrams with two mass scales m and M at the threshold and pseudotreshold that cannot be treated by earlier published formula. The complete reduction to master integrals is given. The master integrals are evaluated as series in ratio m/M and in epsilon with the help of differential equation method. The rules of asymptotic expansion in the case when q^2 is at the (pseudo)threshold are given.Comment: LaTeX, 13 pages, 1 figur

МЕХАНОХИМИЧЕСКИЙ СИНТЕЗ КАРБИДА ВОЛЬФРАМА С УЧАСТИЕМ РАЗЛИЧНЫХ УГЛЕРОДНЫХ КОМПОНЕНТОВ

It has been established that the basic criteria of realization of mechano-chemical tungsten carbide synthesis are the structure of carbon modifications and the degree of their aromaticity. The prospects of application of carbon modifications obtained as a result of pyrolysis of vegetative raw materials for synthesis of tungsten carbide with minimum contents of sulfur are shown.Установлено, что основными критериями реализации механохимического синтеза карбида вольфрама являются структура углеродных модификаций и степень их ароматичности. Показана перспективность использования модификаций углерода, полученных в результате пиролиза растительного сырья, для синтеза карбида вольфрама с минимальным содержанием серы