Effect of the anode-current magnetic field on the motion of electrons in a triode with a virtual cathode

The effect of the anode-current magnetic field on the electron motion in a triode with a virtual cathode is considered. It is shown that the anode-current magnetic field influences the oscillation period and trajectories of electrons. The condition of self-isolation of the electron beam is investigated as a function of the diode parameter. It is shown that the displacement of the beam electrons under the action of the anode-current magnetic field leads to a decrease in the electron phase modulation and an increase in the spread in the electron oscillation amplitude; as a result, the generation efficiency of microwave radiation decreases.     

Addition to the Solution of the Problem on the Motion of a Free Nonrelativistic Electron in a Magnetic Field

In addition to the solution of the quantum mechanical problem on the motion of a free electron in a magnetic field, given by L. D. Landau in his pioneering work, this quantum mechanical problem is solved in view of the fact that the sum of the components of the free kinetic energy of an electron along two axes is a periodic quantity varying identically within the boundaries of every Landau energy level. This periodicity is a consequence of the quantized motion of an electron in a plane normal to the direction of the external magnetic field.     

Diagnostics of a hollow relativistic electron beam from the transfer function of a converting target

Methods for measuring angular, geometrical, and energy characteristics of a hollow relativistic electron beam using the transfer function of a converting target are developed. A relationship between the anisotropy parameters of bremsstrahlung behind the target, angular characteristics of electrons, and geometrical parameters of the electron beam in the target plane is established. The energy balance equation that describes the interaction between the electron beam and converting target is studied. The transfer function of the target and its behavior versus electron energy are found. The time and integral characteristics of the electron beam are examined.     

Models of the Classical Electron after a Century

The point charge and the extended charge as models of the classical electron are studied. The problems inherent to each model with respect to self-interaction are disclosed and the possible solutions are analysed. The possible relation between these models is also discussed. We argue that a totally electromagnetic electron, as well as a point electron, is beyond the scope of classical electrodynamics. This work is intended as a complement to F. Rohrlich's recent account in the sense that it points at challenges still present in the way to a deeper understanding of the electron.     

Amplification of light during the scattering of a relativistic electron by a nucleus in a moderately strong field of a circularly polarized light wave

The amplification (attenuation) factor of an electromagnetic wave during the scattering of a relativistic electron by a nucleus in a moderately strong field of a circularly polarized electromagnetic wave is studied theoretically. The effect of amplification of an electromagnetic field is discovered in a certain interval of polar angles of the incident electron; this interval of angles essentially depends on the electron energy and the field intensity. It is shown that the amplification of a field attains its maximum for nonrelativistic electrons in the range of medium fields. As the electron energy increases, the amplification decreases and vanishes for ultrarelativistic electrons. An increase in the field intensity for a given electron energy also leads to a slow decrease in the amplification of a field. At high intensities of the wave, the effect of amplification vanishes. It is shown that, in the range of optical frequencies for medium fields (F ～ 10⁶V/cm), the amplification factor of laser light may amount to about μ ～ 10^?1 cm^?1 for sufficiently high-power electron beams.     

Completely bound motion of a positive-energy electron in the coulomb field of a motionless nucleus and a uniform magnetic field

We show that the completely bound classical motion of a positive-energy electron is realized in the Coulomb field of a motionless nucleus and a uniform magnetic field. Such a motion exists due to conservation of the so-called invariant tori in the phase space of the system for not only the negative, but also for the positive energy of an electron. The completely bound trajectories occupy a much larger interval of the velocity directions compared with free trajectories for the same energy in a range of distances from the nucleus in which the typical time of the electron transit near the nucleus is larger than the cyclotron-gyration period, while the negative energy of Coulomb interaction is larger (in absolute value) than the total electron energy. The indicated range of distances is realized in the case of a low electron energy or a strong magnetic field when the Larmor radius of the electron is smaller than the characteristic impact parameter of the close Coulomb collisions in the absence of a magnetic field. The required conditions are realized in the photospheres of isolated magnetic white dwarfs and in the experiments on creation of antihydrogen.     

Surface states and the charge of a dust particle in a plasma

We investigate electron and ion surface states of a negatively charged dust particle in a gas discharge and identify the charge of the particle with the electron surface density bound in the polarization-induced short-range part of the particle potential. On that scale, ions do not affect the charge. They are trapped in the shallow states of the Coulomb tail of the potential and act only as screening charges. Using orbital-motion limited electron charging fluxes and the particle temperature as an adjustable parameter, we obtain excellent agreement with experimental data.     

Measurement of electron density distribution in the probe of a low voltage SEM

A method for measuring the electron density distribution in the probe of a low voltage scanning electron microscope is described. It is shown that the focused electron probe of an S 4800 scanning electron microscope at the electron energy of 200 eV has a Gaussian shape of the electron density with the effective diameter of the probe of 20 nm.     

Resonant scattering of a lepton by a lepton in the pulsed light field

The process of resonant scattering of a lepton by a lepton in the field of pulsed light wave in general relativistic case is studied theoretically. The approximation when a pulsewidth is considerably greater than the characteristic time of wave oscillation is considered. The analytical expression for the resonant differential cross-section of concerned process is derived within the framework of the first order of the perturbation theory with respect to external laser field; it contains the resonant peak, the altitude and the width of which are defined by the external pulsed wave characteristics. It is demonstrated, that the resonant differential cross-section of scattering of an electron by an electron (an electron by a positron, an electron by a muon) in the pulsed light field may be several orders of magnitude greater than the corresponding one in the external field absence. The derived results may be verified experimentally for example by scientific facility at SLAC National Accelerator Laboratory.     

Theory of Photo-emission from the Two-Dimensional t-J Model on a Triangular Lattice

The electron spectral function, the electron dispersion, and the electron density of states of the two-dimensional t-J model on a triangular lattice are studied within the selfconsistent fermion-spin mean-field theory. It is shown that there is a gap in the electron dispersions, and the global features of the electron spectral function is qualitatively similar to the result of the t-J model on a square lattice.     

Indication of the ferromagnetic instability in a dilute two-dimensional electron system

The magnetic field B(c), in which the electrons become fully spin polarized, is found to be proportional to the deviation of the electron density from the zero-field metal-insulator transition in a two-dimensional electron system in silicon. The tendency of B(c) to vanish at a finite electron density suggests a ferromagnetic instability in this strongly correlated electron system.     

Studying the possibility of building a single-electron transistor based on a molecule with a monatomic charge center

The single-particle electron energy spectrum and total electron energy spectra of a hydrogenically passivated central fragment of a coordination compound of rhodium with an aurophile terpyridine derivative (CCRATD) in different charge states ranging from–3e to +3e are obtained. The electron transport characteristics for a single-electron molecular transistor based on a CCRATD molecule are calculated and analyzed.     

有限引导磁场下相对论环形电子注色散特性的研究

采用等效媒质处理方法来研究有限引导磁场下沿纵向运动的相对论环形电子注.首先建立运动坐标系以电子注纵向速度匀速运动,在运动坐标系中电子注可以被考虑成静止的磁化等离子体,再通过四维空间的洛伦兹变换得到电子注在静止的实验室坐标系下可以被等效为双各向异性媒质,其不仅具有张量形式的电导率和磁导率,还具有手征特性.在此基础上同时考虑了由于电子注表面波动所引起的表面电流密度.采用该方法研究了有限引导磁场下圆柱波导中沿纵向运动的相对论环形电子注,推导出该模型的色散方程,并进行了数值计算.计算结果表明该研究方法能够得到更准 关键词： 相对论环形电子注 磁化等离子体 色散特性     

Anomalous magnetic moment of the electron in a medium

Radiative effects are considered for an electron moving in a medium in the presence of an external electromagnetic field. Anomalous magnetic moment (AMM) of the electron in -order is calculated under these conditions in the form of two-dimensional integral. Behavior of AMM of high energy electron under influence of multiple scattering in a medium is analyzed. Both mentioned effects lead to reduction of AMM.     

Effects of initial electron beam parameters of a linear accelerator on the properties of bremsstrahlung radiation in a radiotherapy setting

The dependence of the initial electron-beam parameters on absorbed dose distributions have been investigated using a CyberKnife radiotherapy accelerator (Accuray, United States). To describe the initial electron-beam characteristics, simulations of the linear electron accelerator are performed and the electron distributions in the beam of a linac output are analyzed. The radial distributions of electrons are assumed exponential, whereas the energy electron distributions are approximated by monoenergetic and rectangular spectra. There is no significant dependence of depth-dose curves in a phantom on the shape of the electron beam. Importantly, a clear dependence of the radiation field profile on the size of the electron beam is observed not just in the penumbra region, but also in the open part.     

Simulation of the Formation of the Squeezed State of an Electron Beam with a Sublimiting Beam Current in a Closed Drift Tube

Technical Physics - The dynamics of formation of a virtual cathode and the squeezed beam state (SBS) in a setup with a sublimiting relativistic electron beam under repeated input of the electron...     

Images of the phase space diagrams during the unfurling of theelectrons when a plasma expands into a plasma

Using a 1-D1v (one dimension for space, one for velocity) electrostatic particle-in-cell (PIC) code, we simulate the dynamics of the expansion of a plasma into a limited plasma, between two polarized electrodes. We show the phase space diagrams for the two electron families, on which we observe the electron unfurling. The unfurling branches are observed to fold up on the others. The velocity distribution is broadened: the electron population is heated     

Eccentricity of the electron beam in a gyrotron cavity

Dependence of the coupling of the electron beam and RF field in a gyrotron cavity on eccentricity of the electron beam is studied.     

Temperature dependence of the electron self-energy in a polar-crystal slab

In this paper we investigate temperature dependence of the electron self-energy in the polar-crystal slab using Green-function method. We introduce Q2D free Green's function for the first time. Numerical calculations of the electron self-energy using GaAs as an example are performed. The results show that the electron self-energy is a decreasing function of temperature. In calculation, we consider the effect of the excited states on the electron self-energy and find the ground-state energy be about 11% lower than that of bulk polaron. The results also imply that the high excited states pay a larger contribution to the electron self-energy with increasing temperature.     

The spread of the initial energy of electrons in a gyrotron due to the negative-mass instability developing in a magnetron-injector gun

The formation of an electron beam in a magnetron-injector gun of a gyrotron is investigated in the case when it is affected by the negative-mass instability due to the Coulomb repulsion and nonisochronous cyclotron rotation of particles. A technique is proposed for calculating the spread of the initial energy of electrons caused by the instability, which develops as the electron beam moves in the presence of a nonuniform magnetostatic field of the magnetron-injector gun. It is demonstrated that this instability can be one of the main factors providing the energy spread in electron guns of gyrotrons.