Passage of monochromatic radiation through a resonance radiation absorbing medium

The problem of passage of monochromatic radiation pulses through a one-dimensional medium containing several types of nonuniformly distributed absorption centers with coincident energy levels are considered. The physical picture associated with the effect of a brightening wave arising in an optically dense absorbing medium is analyzed. The investigated relations represent a generalization of Bouguer's law for the case of powerful fluxes of monochromatic radiation with allowance for absorption saturation.     

掺杂超晶格量子阱的沟道效应与沟道辐射

分析了超晶格量子阱的沟道效应和沟道辐射,利用正弦平方势描述了掺杂超晶格量子阱沟道粒子的运动行为,并在经典力学框架内,把粒子的运动方程化为摆方程。用Jacobian椭圆函数和椭圆积分解析地给出了系统的解和粒子运动周期,导出了量子阱沟道辐射的辐射强度和辐射能量。结果表明,对于能量为100 MeV左右的电子,辐射能量可达keV量级（X能区）。指出了用量子阱沟道辐射作为X激光或γ激光的可能性。     

Nonlinear absorption of monochromatic radiation in gases

The absorption coefficient as a function of the density of monochromatic collimated radiation is discussed for an arbitrary ratio of natural to Doppler width, with allowance for the effects of collisions between molecules.We are indebted to M.A. El'yashevich for a discussion and to Ya. S. Vasilevskaya and UP. Pesotskaya in preparing the paper.     

Relativistic quantum theory for charged spinless particles in external vector fields

Guided by a diagonalized form of the classical field-energy we construct a time-dependent canonical pair of Schrödinger fields _t (x) and _t (x) which diagonalizes the field-HamiltonianH _t . These Schrödinger fields in general belong to inequivalent representations of the canonical commutation relations for differentt's.The Heisenberg field is constructed by solving the Heisenberg equation of motion and its time-evolution turns out to be governed by a unitary operator, i.e. the Heisenberg fields at different times are unitarily equivalent.Scattering theory (including eventual incoming and/or outgoing bound-states) is finally constructed.     

On the quantum theory of radiation by channeling particles

On the basis of the Dirac equation the intensity of the spontaneous γ-radiation by relativistic channeling particles has been calculated. In the ultrarelativistic limit the quantum treatment gives a result close to that of the classic calculation.     

Spectral method in quantum theory of channeling phenomena of fast charged particles in crystals

We show the possibility of using the spectral method to determine the quantum characteristics of interaction between fast charged particles and crystal when the channeling occurs. Basing on this method, we have developed the procedure for calculation of particles transversal motions eigenlevels for plane channeling. We considered origin of new levels with increasing of particle's energy and zone structure forming from these levels with increasing number of potential wells. We discuss also the possibility of using the spectral method in number of other problems of quantum theory of channeling.     

Drift theory of the resonant interaction of charged particles with wave packets

Averaged equations of motion are obtained for charged particles resonantly interacting with high-frequency wave packets in the case of finite cyclotron radius. It is shown that the mean action of the packet on the particle is not a potential function. Cherenkov resonance of particles with the beats of two wave packets in inhomogeneous plasma is considered.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 10–13, April, 1982.     

Electromagnetic radiation of a charged tachyon moving in a dispersive medium

At the present time a number of studies [1–6] have considered the possible properties of ultrarelativistic tachyon particles. In particular, [5, 6] were dedicated to analysis of the radiation of charged tachyons in a vacuum. The goal of the present study is to analyze the radiation emitted by charged tachyons in an immobile dispersive medium. We will consider the following problem: a charged particle moves with velocity v in an immobile dispersive medium and at time t=0 decays to neutral particles and a charged tachyon which moves at a velocity v₀. The tachyon in turn, because of collisions with neutral particles of the medium, at time t= forms a charged particle (electron) also moving with velocity v.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 130–134, June, 1978.In conclusion, the author expresses his sincere thanks to Professor Ya. P. Terletskii for his interest and aid in the study.     

The quantum theory of the radiation from charged polarized fermions moving in crossed fields

The radiation of a charged Dirac particle, moving at relativistic velocity in orthogonal electric and magnetic fields (E H), is examined here. The formulas obtained are applicable for arbitrary orientation of the particle spin.     

Chaotic dynamics of charged particles in the field of two monochromatic waves in a magnetized plasma

We study the dynamics of charged particles in the presence of two electrostatic waves propagating obliquely to an ambient magnetic field. The presence of a second wave makes the problem a two-dimensional and time-dependent one with a complicated phase space behavior. We derive a set of difference equations (maps) for the nonrelativistic particle motion limit and numerically study them to elucidate the various aspects of the phase space dynamics. For the general case of oblique propagation, we observe synergistic effects leading to the lowering of the stochasticity threshold and the concomitant reduction in electric field amplitudes for particle heating applications. These results can be understood in terms of the resonance structures associated with the two waves and we obtain approximate analytic expressions for the thresholds. For the degenerate case of omega(1)=nOmega,omega(2)=mOmega (where omega(1),omega(2) are the frequencies of the two waves, Omega is the cyclotron frequency and n,m are integers) and strictly perpendicular propagation, the problem simplifies to a one-and-one-half-dimensional one. We observe the presence of stochastic webs in this situation. (c) 1996 American Institute of Physics.     

Coherent electromagnetic radiation of a modulated beam of charged particles

The intensity of electromagnetic radiation produced by a modulated beam of charged particles is estimated. The coherence effect is due to the modulation, i.e. to periodicity in the particles distribution.     

Nonlinear quantum mechanics is a classical theory

Quantum mechanics with nonlinear operators is shown to be an essentially classical theory. A general scheme of delinearization of a quantum theory is described.     

Stark shifts of charged particles in semiconductor quantum wells

 We calculate the effect of a homogeneous electric field on electrons, holes and excitons confined in a quantum well structure consisting of alternate thin layers of well and barrier material. The electric field which acts perpendicular to the quantum well is taken as a perturbation on the quantum well structure confining the charges. The electron and hole energies in the conduction and valence subbands are calculated by solving a one-dimensional Schr?dinger equation. The exciton binding energy is calculated using an improved excitonic model. Results obtained indicate the importance of higher-order excitons in optical transitions at high electric fields. Received: 29 February 1996/Accepted: 19 August 1996     

Relativistic quantum theory of cyclotron resonance in a medium

The relativistic quantum theory of cyclotron resonance in a medium with arbitrary dispersive properties is presented. The quantum equation of motion for a charged particle in the field of a plane electromagnetic wave and in the uniform magnetic field in a medium is solved in the eikonal approximation. The probabilities of induced multiphoton transitions between the Landau levels in a strong laser field are calculated.