干涉仪系统传递函数测量及影响因素的分析

波前功率谱密度(PSD)被用于评价惯性约束聚变(ICF)激光驱动器光学元件中频段的波前误差。干涉仪对PSD较高空间频率分量的测量存在失真效应,可通过干涉仪系统传递函数(STF)的检测标定来获得真实的波前PSD分布。采用台阶板位相比较法测得大口径菲索相移干涉仪检测系统在透射和反射检测情形下的传递函数。对传递函数测试算法进行了比较分析,明确了干涉仪系统zoom倍率的改变等因素对传递函数测量的影响,为波前PSD的准确检测奠定了基础。     

On the problem of the distribution of impurity ions in the F-region of the ionosphere

One-dimensional nonisothermal diffusion in ionospheric plasma (the F-region) is considered in the stationary case. The analysis is carried out for two species of positive ions with allowance for the ionization and recombination processes and the effect of gravity. A system of two coupled equations is derived for the concentrations of the electrons and ions. A transition is made to the case when the ions which determine dissociative recombination are impurity ions. For this case criteria are presented whose fulfilment causes the distribution that has been found to coincide with that obtained by Mange [9] without allowance for photochemical processes.     

Measurements of the QED structure of the photon

The structure of both quasi-real and highly virtual photons is investigated using the reaction , proceeding via the exchange of two photons. The results are based on the complete OPAL dataset taken at centre-of-mass energies close to the mass of the Z boson. The QED structure function and the differential cross-section for quasi-real photons are obtained as functions of the fractional momentum x from the muon momentum which is carried by the struck muon in the quasi-real photon for values of ranging from 1.5 to 400 GeV. The differential cross-section for highly virtual photons is measured for GeV and GeV, where and are the negative values of the four-momentum squared of the two photons such that . Based on azimuthal correlations the QED structure functions and for quasi-real photons are determined for an average of 5.4 GeV. Received: 8 February 1999 / Published online: 28 September 1999     

Analysis of the Topology of the Kerr Metric

The equations of motion of a test particle are integrated for the field of a rotating Kerr black hole (BH) (in accordance with [1]). Due to the lack of analytical transformations for the Carter–Penrose diagrams (CPDs) for the Kerr metric, the topology of the Kerr BH is studied by analytical investigation of the equations of motion. Transformations for the CPDs for the Reisner–Nordström metric are analyzed. The problem of boundary conditions for the Reisner–Nordström topology is analyzed. A solution to this problem of boundary conditions is proposed. It is proved that, in the Reisner–Nordström topology, only one way to go to another universe is possible. For the Kerr topology, the possibility of the existence of an alternative transition to another universe that does not coincide with the universe for the ordinary transition is found. This alternative transition is performed through a surface with a zero radial coordinate (zero radius). Initial conditions for the falling particle are found that correspond to an alternative transition to another universe. The tidal forces acting on a falling body in the Kerr metric are estimated, and the possibility of the transition of the body to other universes without being destroyed by tidal forces is proved.     

On the predictability of the positions of the convergence zones in the ocean

The disagreement between the experimental and calculated positions of the first convergence zone are known from many publications. The most probable cause for such a disagreement, namely, the incorrect specification of the input data for the calculations, is considered. The lack of simultaneity between the hydrological surveys of the region and the acoustic experiments is emphasized. The experimental data obtained by the author in five ocean regions are presented. These data characterize the diurnal variability of the distance from the source to the nearest boundary of the convergence zone. The relations proposed by different researchers for calculating the sound speed from the temperature, salinity, and hydrostatic pressure are analyzed. It is shown that these relations lead to a substantial difference in the estimated depth dependence of the hydrostatic gradient of the sound speed. The position of the first convergence zone is calculated for the propagation conditions determined by vertical temperature and salinity profiles with the subsequent recalculation of these profiles into sound speed profiles by using eight different formulas known from the literature. It is shown that different formulas lead to different values of the distance to the first zone; this difference is substantially greater than that between the calculations and experiment. The necessity of improving the recalculation relations in view of the experimental data on sound propagation in natural oceanic waveguides, including the data on the actual positions of the convergence zones, is emphasized.     

On the calculation of the bremsstrahlung in the region of the plasma frequency

On the basis of the classical theory of radiation produced in incomplete Coulomb interaction, a formula is derived for the coefficient of the bremsstrahlung of fully ionized plasma. In the region of rectilinear approximation a comparison is made with the results of the quantum formula derived from the Born approximation. Furthermore, the influence of dispersion upon the emission coefficient is taken into account; some relations for the region of dispersion are given.     

Contributions of the cornea and the lens to the aberrations of the human eye

The relative contributions of optical aberrations of the cornea and the crystalline lens to the final image quality of the human eye were studied. The aberrations of the entire eye were obtained from pairs of double-pass retinal images, and the aberrations of the cornea were obtained from videokeratographic data. Third-order spherical aberration and coma were significantly larger for the cornea than for the complete eye, indicating a significant role of the lens in compensating for corneal aberrations. In a second experiment retinal images were recorded in an eye before and after we neutralized the aberrations of the cornea by having the subjects wear swimming goggles filled with saline water, providing a direct estimate of the optical performance of the crystalline lens.     

Application of the Jost Function for Calculation of the Discrete Spectrum of the Helium Atom

Russian Physics Journal - A method for calculating bound states of the helium atom is proposed based on searching for roots of the Jost function for the process of electron scattering by a singly...     

大气湍流对遥感系统分辨力的影响

以平面波为例,分别针对较弱和较强的湍流模型,通过计算到达角起伏讨论了高空光学遥感系统由大气湍流引起的地面图像分辨力问题。结果表明,对于给定的遥感系统口径和高度,较强湍流引起的图像分辨力的1cm左右;而较强湍流引起的图像分辨力则可达10cm量级。对于自身的地面分辨力具有m的量级的传统光学遥感系统,上述影响并不明显。对于现代高辨力光学遥感系统,这种影响便不容忽略,特别是对较强的湍流,往往需要用自适应光学等方法加以补偿。     

Control of the spectrum of the biphoton field

The main methods for controlling the biphoton field, as well as the problems for which the width and the shape of the spectrum of the biphoton field are of decisive importance, are discussed. The method for controlling the spectrum of the spontaneous parametric downconversion of light based on the spatial modulation of the refractive indices of a nonlinear crystal in which the generation of biphotons has been analyzed. Modulation is due to the thermo-optic and electro-optic effects.     

Influence of the thickness of the liquid layer on the ratio of the dimensions of a convection cell

A theory is developed for a new type of transition — a change in the ratio of the longitudinal and transverse dimensions of a convection cell as the thickness of a liquid layer is varied. A sudden change in the ratio of the cell dimensions takes place because of a change in the predominant mechanism for excitation of convection. The governing influence of buoyancy forces gives way to one of thermocapillary forces, and they in turn give way to the influence of thermoelectric forces for yet thinner layers. As the layer thickness is reduced gradually at a fixed external heating, the ratio of the dimensions will take on the values 0.7, 0.65, and 1, respectively. Zh. Tekh. Fiz. 68, 7–11 (November 1998)     

Design and analysis of the tunnel connecting the beamcorridor and the spectrum hall of the CSNS

There is a tunnel connecting the beamcorridor and the target station in the spectrum hall in the CSNS project.The length of the tunnel is about 20 m.The shielding design of the tunnel is very significant for the persons working in the spectrum hall because the tunnel is not covered ed soil for shielding.In order to reduce the dose rate at the exit of the cable ducts,we use the ISIS construction,which is designed with four turnings,as a reference for the tunnel design.The thickness of the shielding is obtained by a simulationwith the Monte Carlo Code FLUKA.The result is compared with the data obtained with Moyer Mode and the reliability of the simulation is proved.This paper provides the basis for the design of the tunnel.     

Calculation of the interruption function in the fourth order of the perturbation theory

General expressions for fourth-order terms for calculating the interruption function S(b) in terms of the perturbation theory are derived for molecules with different symmetry properties and arbitrary trajectories of the relative motion of colliding molecules. An expression for a quadruple integral over time appearing in the definition of new resonance functions is written in terms of the Fourier transform of the coefficients of the intermolecular interaction potential.     

On the Locality of the No Hair Conjecture and the Measure of the Universe

We reanalize the recently proposed proof by Jensen and Stein-Schabes [1] of the No Hair Theorem for inhomogeneous spacetimes, putting a special emphasis on the asymptotic behaviour of the shear and curvature. We conclude that the theorem only holds locally and estimate the minimum size a region should be in order for it to inflate. We discuss in some detail the assumptions used in the theorem. In the last section we speculate about the possible measure of the set of spacetimes that would undergo inflation.     

On the calculation of the Debye-Waller factor of alloys

Relations are derived and discussed for the temperature dependence of the diffraction of X-rays on alloys. It is shown that in a certain approximation one can separate the influence of the inter-atomic force constants from that of the masses of the alloy atoms. A reciprocal matrix is found for the linear chain and the equation for the diffraction of X-rays on an alloy is transformed in a certain approximation to an equation for diffraction on a perfect chain.     

Influence of the polarisation of the medium on the radiation of channeled particles

The theory of the electromagnetic radiation from channeled particles is developed with inclusion of a virtual photon interaction with the crystal. Simple estimates are made for the spectral and angular distribution of the radiation. It is shown that the polarisation of the medium may lead to a drastic shrinking of the frequency range allowed for the radiation. The possibility of an increase of the transverse energy of a particle caused by radiation is predicted.     

Amplification of electromagnetic field in the course of the nonrelativistic electron scattering by ion in the presence of the field of the medium-intensity elliptically polarized light wave

The amplification factor of the electromagnetic field is theoretically studied for the scattering of nonrelativistic electrons by ions in the presence of the field of the elliptically polarized electromagnetic wave. A simple analytical formula for the gain is derived for the medium-intensity range. The formula supplements and extends the domain of applicability of the known Marcuse formula for the linear polarization in the presence of a weak field. It is demonstrated that the maximum gain is reached when the initial electron velocities belong to the polarization plane of the electromagnetic wave. In the range of optical frequencies, the amplification factor of the laser radiation can be significant for relatively high powers of electron beams.     

On the Diagonalization of the Bethe–Salpeter Equation for the Imaginary Part of the Scattering Amplitude

The Bethe–Salpeter (BS) equation for the imaginary part of the scattering amplitude is examined in the ladder approximation of scalar quantum electrodynamics (QED). Asymptotic solutions of the BS equation derived for the imaginary part of the scattering amplitude are shown to exhibit the Regge amplitude behavior for small momentum transfer and scattering in the forward direction and at arbitrary angles.     

Design and analysis of the tunnel connecting the beamcorridor and the spectrum hall of the CSNS

There is a tunnel connecting the beamcorridor and the target station in the spectrum hall in the CSNS project. The length of the tunnel is about 20 m. The shielding design of the tunnel is very significant for the persons working in the spectrum hall because the tunnel is not covered by soil for shielding. In order to reduce the dose rate at the exit of the cable ducts, we use the ISIS construction, which is designed with four turnings, as a reference for the tunnel design. The thickness of the shielding is obtained by a simulation with the Monte Carlo Code FLUKA. The result is compared with the data obtained with Moyer Mode and the reliability of the simulation is proved. This paper provides the basis for the design of the tunnel.