Anomalous penetration of an electromagnetic field into a nonisothermal plasma with two species of ions

It is shown that a change in the ion composition of a nonisothermal plasma is accompanied by nontrivial changes in the effective penetration depth of a strong quasi-stationary electromagnetic field generating ion-acoustic instability.     

Fermi energy of electrons in a thin metallic plate

A strict analytical expression for the Fermi energy of electrons in a thin metallic plate as a function of the plate thickness at a given electron density has been derived for the first time. The derivation has been carried out taking into account the size quantization in the free-electron approximation at zero temperature.     

Regularities in penetration of electromagnetic waves through metallic magnetic films

Penetration of millimeter electromagnetic waves through permalloy films under magnetic resonance conditions is studied experimentally and theoretically. Measurements are taken on film samples from 40 to 200 nm in thickness in a frequency range from 26 to 38 GHz. Magnetic resonance, antiresonance, and spin-wave resonance are observed. The resonance spectrum is reconstructed. The Gilbert damping constant is determined for a series of films. It is shown that the damping constant decreases upon an increase in the film thickness. The resonance line profile is calculated, and the dependences of resonance line amplitude and width on experimental conditions and material parameters of the film are determined.     

金属薄板弹性各向异性检测

当平面声波入射到液体中的金属薄板上时，透射系数将随声波入射角变化，根据这一规律，能够准确地测定声波入射面与金属薄板交线方向上金属板材料的弹性常数，测得金属薄板面内不同方向的弹性常数，对金属薄板弹性各向异性情况将有一清蜥的认识，由于测试过程采用微机控制、数据采集和处理，实现了各向异性测量的全自动化，该方法测试时间短、所需样品小且加工方便，并可测试金属薄板弹性各向异性的均匀度。     

Local fracture of thin metallic films during electromagnetic loading

The pulsed electrodynamic fracture of thin (10–50 nm) aluminum films deposited onto polymer substrates is experimentally studied. The fracture of the films manifests itself in the form of discontinuity (crack) channel growth across an applied electric field. The roles of a magnetic pressure, thermomechanical stresses, and Joule heating at the tip of a growing crack are analyzed at high current densities (∼10¹⁰−10¹² A/m²). In contrast to the results well known for the electrodynamic fracture of bulk metallic samples, the first two factors in the films are insignificant. The effect of the electric explosion of the crack tip is found to play a key role in the beginning of fracture.     

Modulational instability of matter waves under strong nonlinearity management

We study modulational instability of matter-waves in Bose-Einstein condensates (BEC) under strong temporal nonlinearity-management. Both BEC in an optical lattice and homogeneous BEC are considered in the framework of the Gross-Pitaevskii equation, averaged over rapid time modulations. For a BEC in an optical lattice, it is shown that the loop formed on a dispersion curve undergoes transformation due to the nonlinearity-management. A critical strength for the nonlinearity-management strength is obtained that changes the character of instability of an attractive condensate. MI is shown to occur below (above) the threshold for the positive (negative) effective mass. The enhancement of number of atoms in the nonlinearity-managed gap soliton is revealed.     

电磁干扰下时间分辨测量系统信号外触发技术

在实验的基础上给出了束参数时间分辨测量系统的实验布局和特点,分析高压电磁干扰对直线感应加速器中时间分辨测量系统外触发性能的影响和变化规律;进一步探讨系统高压电磁干扰后的抑制措施。针对电磁空间干扰情况,主要通过采用光纤传输控制信号的措施,能很好地传输窄脉冲,信号延时抖动小于2 ns,达到了高速信号的可靠传输要求,采用嵌入式控制器既解决了抗电磁干扰的要求,也满足了束参数时间分辨测量系统的使用要求。     

电磁干扰下时间分辨测量系统信号外触发技术

在实验的基础上给出了束参数时间分辨测量系统的实验布局和特点,分析高压电磁干扰对直线感应加速器中时间分辨测量系统外触发性能的影响和变化规律;进一步探讨系统高压电磁干扰后的抑制措施。针对电磁空间干扰情况,主要通过采用光纤传输控制信号的措施,能很好地传输窄脉冲,信号延时抖动小于2ns,达到了高速信号的可靠传输要求,采用嵌入式控制器既解决了抗电磁干扰的要求,也满足了束参数时间分辨测量系统的使用要求。     

Analysis of the conditions for ultradeep penetration of powder particles into a metallic matrix

The critical conditions for ultradeep penetration of particles when a flux of high velocity particles interacts with a matrix material are examined from the standpoint of nonequilibrium thermodynamics. The problem of the change in entropy consistent with their deformation during loading is solved qualitatively for the example of aluminum and copper samples. It is shown that ultradeep penetration of particles is a system process of mass and energy transfer owing to a developed instability in the material caused by the shock-wave action of the particle flux. The degree of disequilibrium of the process is described by the dependence of the change in entropy on the deformation of the matrix material. It turns out that the ultradeep particle penetration process occurs only in a region lying beyond a bifurcation point. Zh. Tekh. Fiz. 68, 124–125 (July 1998)     

Anomalous electromagnetic waves in a multicomponent insulator

The permittivity of an amorphous insulator consisting of several types of molecules is found. The concepts of polarizability averaged over molecule types and of polarizability fluctuation are introduced, which, when taken into consideration, impart dispersive properties to the permittivity of the medium. It is shown that, near the frequencies at which the average polarizability vanishes, the permittivity depends on the average quadratic fluctuation of the molecular polarizability. Anomalous electromagnetic waves in these frequency intervals are considered.     

Relaxation under conditions of strong interaction

A method is developed for considering a nonequilibrium transition in an isolated system when the correlation time [2] and relaxation time are of the same order. The perturbation V in the Hamiltonian of (1.1) is not restricted in any way. The method is based on the assumption [4] that it is possible to use a representation in which the indeterminacy of the energy of a nonstationary system appears explicitly.     

Anomalous lepton moment in a non-Abelian gauge model in an intense electromagnetic field

The effect of an external electromagnetic field on the magnitude of the anomalous magnetic moment (AMM) of a lepton in the Weinberg model (1967) is investigated using the method of analytic continuation, previously applied to problems in quantum electrodynamics with an external field. The behavior of the AMM is studied as a function of the value of the dynamic parameter X=p_oH/mH_o.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 26–28, January, 1983.     

Secondary buckling patterns of a thin plate under in-plane compression

We study the nonlinear deformations of a long rectangular elastic plate clamped along its edges and submitted to in-plane biaxial compression. Using the F?ppl-von Kármán equations, we predict various secondary buckling modes according to the applied longitudinal and transverse compressions. A model experiment is carried out in a thin polycarbonate film, and the observed buckling patterns are found in good agreement with theory. Pattern selection in the delamination of compressed thin films is discussed in the light of these results. Received 22 January 2002