Multicyclic fatigue of stainless steel treated by a high-intensity electron beam: surface layer structure

It is shown that an electron-beam treatment of the 08X18H10T steel specimens under the condition of melting of the ~5 μm surface layer (electron beam energy density 25 J/cm²) increases their fatigue life by a factor of 3.5. The structural-phase states and defect substructure of this steel are studied by the methods of optical, scanning and transmission electron microscopy, and the factors responsible for its increased fatigue life are revealed.     

On the modulation of an electron beam by the slow light wave

The modulation of an electron beam with a large energy spread at optical frequencies on the basis of the stimulated Cherenkov absorption has been shown to posses an advantage over the Schwarz and Hora method. Two possible realizations of the Cherenkov modulation scheme are proposed.     

Hardening of steel by alloying in a relativistic electron beam

The possibility was demonstrated of hardening a steel surface layer by alloying it using the energy of relativistic electrons. Investigations were made of how the structure, hardness, and depth of the hardened layer depend on the processing regime and on the initial temperature of the steel in the case of alloying with boron carbide and with Cr+C and Cr+B₄C mixtures. The greatest hardening was achieved by alloying with a mixture of Cr and B₄C powders. This was due to a higher volume fraction of the second phase in the layer and to the precipitation of chromium carboborides. Several types of alloying utilizing Cr+B₄C and containing additional agents and modifiers were developed on the basis of the data obtained.Institute of Hardening Physics and Materials Research, Siberian Branch of the Russian Academy of Sciences. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 57–63, March, 1993.     

Backscattering of an intense laser beam by an electron

We present a novel, simple asymptotic expansion for the spectrum of radiation that is backscattered from a laser by a counterpropagating (or copropagating) electron. The solutions are presented in such a way that they explicitly show the relative merit of using an intense laser and of an energetic electron beam in x-ray production in the single particle regime. Simple scaling laws are given.     

Silicon dioxide modification by an electron beam

The overheating temperature of a microvolume of silicon dioxide produced by bombardment by a high specific-power electron beam has been estimated. Calculations showed that the maximum temperature to which a microvolume of silicon dioxide is overheated can be as high as 1200°C for an electron beam current of 100 nA. The variation in the cathodoluminescence characteristics of amorphous silica with different contents of hydroxyl groups was studied for various electron beam specific-power levels. The impact of a high specific-power electron beam was shown to create additional lattice defects up to the formation of silicon clusters.     

RAFM钢TIG焊和电子束焊疲劳性能实验和分析模拟

利用ANSYS 对低活化铁素体马氏体(RAFM)钢进行非熔化极气体保护焊(TIG 焊)与电子束焊的抗疲劳模拟分析，再利用SDS200 电液伺服疲劳试验机对TIG 焊和电子束焊的两种RAFM 钢试件进行实验。通过施加相同梯度负荷对TIG 焊和电子束焊试件进行焊缝的疲劳性能实验。与实验结果对比分析，结果显示电子束焊优于 TIG 焊，但在一定负载下可以用TIG 焊代替电子束焊。     

On the 1920 Å continuous spectrum of the supersonic argon jet excited by an electron beam

The T₀/?(T₀) dependences (T₀ is the intensity of the 1920 Å continuum at its maximum, ? is the concentration of argon atoms at the intersection of an electron beam and a jet, T₀ is the temperature of argon at the nozzle) for the 1920 Å continuum radiated by a supersonic argon jet excited by an electron beam were investigated at various pressures of argon at the entry to a nozzle. The experiments performed suggested a possible generation mechanism of the 1920 Å continuum emitted by an argon jet.     

电子束驱动的回旋激射不稳定性

对弱相对论性电子束驱动的回旋激射(maser)不稳定性的一般理论作了详细讨论.对在获得增长率实用表达式过程中若干解析表达式的推导与细节做了仔细的补充讨论和说明，还增加了增长率的近似表达式，并由此得到了回旋激射不稳定性主要特征的解析分析以及与精确计算的比较，使整个理论有一个完整的描述.侧重解析讨论，也提供了部分一般性的数值计算结果. 关键词： 回旋激射不稳定性 弱相对论性电子束 增长率     

Plasma instabilities excited by an azimuthal electron beam

The paper describes the effect of the finite temperature T of an azimuthal electron beam on plasma stability. Only instabilities for which the longitudinal macroscopic velocity of the beam is of no importance are discussed. It is shown that at the limit of applicability the weak and strong inhomogeneity approximations give the same results.     

On the pumping of plasma lasers by a high-frequency-modulated electron beam

The possibility of effective pumping of plasma lasers by a high-frequency-modulated electron beam, i.e. an electron beam in the form of a periodic train of electron bunches, is discussed. It is shown that if such parameters of the medium as the relaxation times of the electron temperature ρ_Te and the electron density ρ_Ne are in agreement with the pulse width ρ_p and the interval between pulses, 1/?_m, this will facilitate effective laser pumping and amplitude modulation of the laser radiation. Existing microwave tubes, such as a traveling-wave tube and a klystron, provide the required parameters of a periodic train of current pulses (electron bunches) over a wide range of pulse widths ρ_p and pumping current amplitudes.     

Microstructure evolution occurring in the modified surface of 316L stainless steel under high current pulsed electron beam treatment

High current pulsed electron beam (HCPEB) surface treatment of 316L stainless steel (SS) was carried out with a wide spectrum of treating parameters. Microstructure changes occurring in the modified surface were characterized with microscopy, X-ray diffractometry and electron backscatter diffractometry (EBSD) techniques. The evolution regularities of surface craters and microstructure refinement, as well as preferred orientation of (1 1 1) crystal planes were discussed on considering the coupled temperature-stress fields formed in surface layers after an absorption of HCPEB energy.     

Surface modification of Al-20Si alloy by high current pulsed electron beam

Hypereutectic Al-20Si (Si 20 wt.%, Al balance)alloy surface was treated with high current pulsed electron beam (HCPEB) under different pulse numbers. The results indicate that HCPEB irradiation induces the formation of metastable structures on the treated surface. The coarse primary Si particle melts, producing a “halo” microstructure with primary Si as the center on the melted surface. A supersaturated solid solution of Al is formed in the melted layer caused by Si atoms dissolving into the Al matrix. Cross-section structure analysis shows that a 4 μm remelted layer is formed underneath the top surface of the HCEPB-treated sample. Compared with the matrix, the Al and Si elements in the remelted layer are distributed uniformly. In addition, the grains of the Al-20Si alloy surface are refined after HCPEB treatment, as shown by TEM observation. Nano-silicon particles are dispersed on the surface of remelted layer. Polygonal subgrains, approximately 50-100 nm in size, are formed in the Al matrix. The hardness test results show that the microhardness of the α(Al) and eutectic structure is increased with increasing pulse number. The hardness of the “halo” microstructure presents a gradient change after 15 pulse treatment due to the diffusion of Si atoms. Furthermore, hardness tests of the cross-section at different depths show that the microhardness of the remelted layer is higher than that of the matrix. Therefore, HCPEB technology is a good surface modification method for enhancing the surface hardness of hypereutectic Al-20Si alloy.     

On the self-consistent states of a planar vacuum diode with an electron beam

The self-consistent stationary solutions for a planar vacuum diode with a monoenergetic electron beam are fully classified. Formulas are presented to calculate potential distributions of all types and the maximum electric current that can pass through the diode under steady-state conditions at an arbitrary applied voltage. The stability of the solutions is studied.     

Exchange self-polarization of an electron beam

Self-organization of a beam of free electrons injected by an optical cathode is discussed. It is shown that exchange interaction may cause beam self-polarization in a vacuum and sustain beam polarization in the material.     

强流电子束碰撞电离背景气体研究

利用数值计算与粒子模拟两种方法,结合实际的实验数据,对高功率微波二极管中相对论电子束与背景气体相互作用碰撞产生的等离子体密度进行了研究.研究结果表明：碰撞产生的等离子体密度数值计算结果与粒子模拟结果基本一致,背景气压在0.01 Pa—0.05 Pa时,碰撞产生的等离子体密度在4—12×10⁹cm^-3,即便在考虑电子离子复合的情况下,数值计算结果与粒子模拟结果依然符合得很好.另外,粒子模拟结果表明：随着气压的增加,等离子体密度呈现先增大再减小然后又逐渐增大的过程, 关键词： 相对论电子束 等离子体 数值计算 粒子模拟     

Installation for studying the plasma of Z-pinch initiated by an electron beam

An installation is developed for studying the dynamics of Z-pinch plasma with the discharge initiation by an electron beam. Research and commissioning works are performed for creating a system of electron beam formation using the adiabatic plasma lens. The study results are presented.     

On the nature of emissions of polymethyl methacrylate excited by an electron beam of subnanosecond or nanosecond duration

The results of studies of the physical nature of emissions produced in polymethyl methacrylate excited by electron beams of a subnanosecond or a nanosecond duration are presented. The spatial, amplitude, and spectral-kinetic properties of emissions have been examined under an electron beam energy density varying from 10^–4 to 4 × 10^–1 J/cm². It has been found that cathodoluminescence is the primary type of emission under low energy densities of the electron beam. When the energy density of a nanosecond electron beam and/or the number of pulses of excitation by a subnanosecond electron beam were increased, an electrical breakdown of polymethyl methacrylate occurred in the irradiated region. This process was accompanied by a burst of emission of dense, low-temperature plasma.     

Evolution of the dislocation substructure in an annealed pro-eutectoid steel upon irradiation with a high-current electron beam

The gradient evolution of the dislocation substructures of an annealed pro-eutectoid steel whose surface was treated with a pulsed low-energy, high-current electron beam has been quantitatively analyzed with the use of transmission diffraction electron microscopy.     

Structural analysis of electron beam irradiated steel/molybdenum systems

Layered systems, obtained by e-beam irradiation of molybdenum sheets mechanically clamped to ARMCO iron, plain carbon steel and high alloy austenitic steel substrates, have been analysed by means of conversion X-ray Mössbauer scattering and X-ray diffraction. When the substrate is iron or carbon steel, the structure of the surface layer is completely ferritic with a certain amount of iron-atoms coordinated with molybdenum atoms. If the substrate is fully austenitic, the e-beam treated surface structure presents a broad ferritic-martensitic component. The influence of the cooling rate of the e-beam molten layer is also discussed in relation to the observed surface structures.