Intense Pulsed Electron Beam Research Articles

Stability domain of alumina thermally grown on Fe–Cr–Al-based model alloys and modified surface layers exposed to oxygen-containing molten Pb

The paper gives experimental results concerning the morphology, composition, structure and thickness of the oxide scales grown on Fe–Cr–Al-based bulk alloys during exposure to oxygen-containing molten lead. The results are discussed and compared with former results obtained on Al-containing surface layers, modified by melting with intense pulsed electron beam and exposed to similar conditions.The present and previous results provide the alumina stability domain and also the criterion of the Al/Cr ratio for the formation of a highly protective alumina layer on the surface of Fe–Cr–Al-based alloys and on modified surface layers exposed to molten lead with 10−6 wt.% oxygen at 400–600 °C. The protective oxide scales, grown on alumina-forming Fe–Cr–Al alloys under the given experimental conditions, were transient aluminas, namely, kappa-Al2O3 and theta-Al2O3.

Surface-alloy formation in film–substrate melting by intense pulsed electron beam. Part 2

The elemental and phase composition and defect structure of the surface layer on 5140 steel is considered after alloying by melting of a film–substrate (5140 steel) system under irradiation by intense pulsed electron beam; the film consists of aluminum or titanium. Treatment of the titanium–5140 steel system results in alloying to the depth of the molten layer (about 15 μm); polycrystalline structure (with submicron grains) based on α-phase hardened by titanium-carbide nanoparticles is formed. For the aluminum–5140 steel system, only a thin surface layer (about 2 μm) is alloyed, on account of the evaporation of aluminum from the steel surface. Martensit structure hardened by iron-aluminide nanoparticles is formed.

Surface structure of commercially pure VT1-0 titanium irradiated by an intense pulsed electron beam

It is shown that pulsed electron beam irradiation of commercially pure titanium at a beam energy density of 10 J/cm2, pulse duration of 150 μs, number of pulses of N = 5 pulses, and pulse repetition frequency of 0.3 Hz with attendant polymorphic α→β→α transformations allows a more than five-fold decrease in the grain and subgrain sizes of the material structure.

Infrared imaging diagnostics for intense pulsed electron beam.

Infrared imaging diagnostic method for two-dimensional calorimetric diagnostics has been developed for intense pulsed electron beam (IPEB). By using a 100-μm-thick tungsten film as the infrared heat sink for IPEB, the emitting uniformity of the electron source can be analyzed to evaluate the efficiency and stability of the diode system. Two-dimensional axisymmetric finite element method heat transfer simulation, combined with Monte Carlo calculation, was performed for error estimation and optimization of the method. The test of the method was finished with IPEB generated by explosive emission electron diode with pulse duration (FWHM) of 80 ns, electron energy up to 450 keV, and a total beam current of over 1 kA. The results showed that it is possible to measure the cross-sectional energy density distribution of IPEB with energy sensitivity of 0.1 J/cm(2) and spatial resolution of 1 mm. The technical details, such as irradiation protection of bremsstrahlung γ photons and the functional extensibility of the method were discussed in this work.

Surface-alloy formation in film–substrate melting by intense pulsed electron beam. Part 1

The elemental and phase composition and defect structure of the surface layer on 40X steel is compared for two cases: (1) treatment by intense pulsed electron beam; (2) alloying by melting of a film–substrate (copper–40X steel) system under irradiation by intense electron pulses. The evolution of the structure in the steel’s surface layer is studied as a function of the energy density of the pulsed electron beam. Highspeed solidification and subsequent quenching of 40X steel leads to the formation of a modified layer (thickness up to 30 µm). Cell structure is formed in the surface layer; the mean cell size is increased from 240 to 500 nm with increase in energy density of the pulsed electron beam from 10 to 20 J/cm2 (ten pulses). The treatment of a film–substrate (copper–40X steel) system by intense electron pulses is accompanied by the formation of surface alloy with quenched structure, hardened by copper nanoparticles.

Fatigue life of silumin irradiated by high intensity pulsed electron beam

The electron-beam processing of silumin, leading to the evolution of structure-phase state of its surface is carried out. It has been shown that this alloy is a multiphase material and contains, except an aluminum-based phase, the particles of intermetallic compounds of Al-Si- Fe-Mn. It is shown that electron beam treatment of the eutectic silumin surface increases the fatigue service life more than in 3.5 times. The analysis of structure-phase states modification of silumin subjected to electron beam treatment with the following fatigue loading up to the failure is carried out by methods of optical and scanning electron diffraction microscopy. Analysis of the surface layer structure revealed the sources of nucleation of submicrocracks. It is revealed that the large silicon plates located on the surface and in the subsurface layer are the most dangerous stress concentrators.

Increasing the fatigue life of steel and alloys by electron-beam treatment

The number of cycles to failure for 08X18H10T, 20X23H18, 2X13, and Э76Ф steel and Silumin (Al–12% Si alloy) may be increased by a factor of 3.5 by electron-beam treatment with the following parameters: energy density of the electron beam 10–40 J/cm2; pulse length 50–150 µs; 3–5 pulses; and pulse frequency 0.3 s–1. By scanning and transmission electron-diffraction microscopy, the structure and phase states and defect substructure of these materials may be investigated. The increase in the fatigue life of the steel is due to the transformation of the surface structure of the material under the action of the intense pulsed electron beam. In physical terms, the influence of the multilevel structure and phase state on the mechanical properties of the surface layer indicates redistribution of the elastic energy both on account of the interaction of the elastic fields of structural elements at different scale levels and on account of the reduction of the scale level corresponding to localization of the plastic deformation.

Formation of the surface alloys by high-intensity pulsed electron beam irradiation of the coating/substrate system

The results of the analysis of the structure and properties of the surface layer of aluminum A7 subjected to alloying by the intense pulsed electron beam melting of the film / substrate system. Fold increase in strength and tribological properties of the modified surface layer due to the formation of submicro - nanoscale multiphase structure have been revealed.

An average method for intense pulsed electron beam incident angles

Electron incident angles have a heavy effect on the energy deposition profile (EDP) in material of the intense pulsed electron beam. The average of electron incident angles must be taken into consideration when carrying out the diagnosis technology research and numerical simulation study, while a widely received method to solve the problem has not yet been presented. This article gives a qualitative analysis on the energy deposition function, which is formed by the energy loss function and energy deposition efficiency function. An average method of electron beam incident angles based on EDP, which is named as EDP average method, is developed, and a qualitative explanation of the electron beam EDP curve is given. The error and applicability of this method are analyzed. M-C tests are designed for comparison with theoretical analysis. The EDP average method has a better performance in calculation of the EDP than the method using arithmetic average directly, especially in the shallow of target material.

Simulation on surface morphology evolution of metal targets irradiated by intense pulsed electron beam

Based on the review of previous experimental and theoretical studies on the surface processing by a pulsed intense electron beam, the induced temperature field in aluminum and 304 stainless steel is simulated by the finite element method (FEM) to estimate the existing time and depth of molten metal flow field on the irradiated surface. The generation of craters is attributed to the thermal resistance formed by the grain boundaries, and the influence of material properties on the mechanism of crater evolution is also discussed. Two-phase flow field simulation on molten metal is carried out with a combination of level-set method and FEM to estimate the mass transfer behavior at the craters and surface protuberance. It is revealed that the mass transfer effect driven by surface tension is an important factor for the formation and evolution of round-shaped craters on the surface of metals with high melting point, viscosity and surface tension coefficient. However, for metals with low melting point, due to the strong disturbance by ablating gas plume and low surface tension effect, the craters are more likely to have irregular splashing edges.

一种强流脉冲电子束入射角等效计算方法

一种强流脉冲电子束入射角等效计算方法

Characterization and analysis of infrared imaging diagnostics for intense pulsed ion and electron beams

A two-dimensional calorimetric diagnostic technique with infrared imaging method has been developed. The technique, which enables the measuring of two-dimensional energy density distribution of intense pulsed ion beam (IPIB) and intense pulsed electron beam (IPEB) with particle energy typically of hundreds of keV, is applicable for the diagnostics of IPIB and IPEB for material treatment purpose such as fast quenching, surface melt coating, etc. Testing of the technique has been carried out with IPIB on pulsed ion beam accelerator BIPPAB-450. The maximum ion energy was 450 keV, the density of the ion current was 150 A/cm 2 , and the pulse duration (at half height) was 80 ns. The results showed that the technique can achieve surface energy density sensitivity of 0.1 J/cm 2 and spatial resolution of 1 mm. Also, the validity and precision of the method was checked by establishing a modeling based on Fourier's Law with Finite Element Method (FEM). The applicability and principles of the technique for IPIB and IPEB was also discussed reasonably. • Infrared imaging diagnostics developed for intense pulsed ion/electron beams. • Principals, validation and applicability of the method. • 2-D Energy distribution, stability and focusing test results with the method. • Analysis of optimization of the method under different circumstances.

Metal surface layers after pulsed electron beam treatment

Irradiation of metal targets with intense pulsed electron beams leads to rapid melting and solidification of the target surface layers. For beams generated by the GESA facility with 120kV acceleration voltage, 20–80J/cm2 beam energy density, and 20–50μs pulse duration, the induced changes in material properties are accompanied by the evolution of a topographical pattern on the target surface, typically tens of micrometers in height and hundreds of micrometers laterally. In this work, GESA-modified surface layers of stainless steel, copper, and aluminum alloy targets are characterized by a post-treatment study. Larger surface roughness is found for treatment with an electron beam of higher energy density. Similarly, the roughness amplitude increases for the repetitive application of high energy density pulses (60–80J/cm2, 40–50μs). Several shorter pulses with lower energy density (~30J/cm2, 25–30μs) lead to a coarsening of the surface features. The target material inhomogeneity and the aspect of the melt front are investigated by cross-sectional analysis. Material homogenization is observed in the melted surface layer. Straight melt fronts are found for stainless steel, whereas aluminum alloy shows non-uniform melting. Based on the experimental findings, different processes and their influence on the surface layer dynamics during the melted stage are discussed. These include intense evaporation and dissolution of inclusions into the surrounding melt material.

Surface Layer Dynamics During E-Beam Treatment

The interaction of a pulsed intense electron beam with a metal target leads to rapid heating and subsequent cooling of the surface layer, accompanied by a series of phase transitions among the solid, liquid, vapor, and plasma phase. As a consequence of the treatment, depending on the beam parameters, the metal target is eroded and a topographical pattern (waviness, craters, etc.,) evolves on its surface. Surface roughening, a major drawback of pulsed intense electron beam treatment, is well known but lacks comprehensive understanding. In this paper, the process of pulsed intense electron beam interaction with metal targets is studied with special attention to the dynamics of the target surface layer and the development of surface roughness. The pulsed electron beam facility GESA generates electron beams with power density 0.5-2 MW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , electron energy up to 120 keV, and pulse duration up to 200 μs. Different fast in situ diagnostics are applied to study the various processes occurring at the target surface: 1) melting and resolidification are visualized by time and space resolved imaging of the surface specular reflectivity; 2) spectroscopy is used to characterize the plasma phase adjacent to the target surface; 3) the evolution of irregularities and bubbles at the surface is studied by high-resolution microscopy; and 4) a stroboscopic imaging technique is applied to catch the evolution of the surface topography. The experimental data are compared with numerical simulations of heat transfer. All results and processes involved in pulsed intense electron beam treatment are discussed with respect to the target surface layer dynamics.

Novel Injector of Intense Long Pulse Electron Beam for Linear Plasma Devices

A novel high-power (10 MW) sub-millisecond electron beam is developed for injection into the open (linear) plasma devices. The beam is produced by extraction of electrons from a plasma of pulsed arc discharge in hydrogen. The beam is extracted and accelerated with multiaperture diode-type electron optical system with 241 small round apertures, which are arranged in a hexagon-al pattern. The injector prototype was installed into the end plasma tank of GOL-3 multiple mirror trap and tested to produce an electron beam with up to 100 keV electron energy, about 100 A total beam current and 0.7 ms or longer pulse duration. In a series of preliminary experiments the electron beam was injected into the GOL-3 plasma chamber filled with deuterium gas with a density of 1014-1015cm-3 and transported in a corrugated magnetic field (<B> up to 1.4 T) along the trap at a distance of 12 m.

Improving oxidation resistance and thermal insulation of thermal barrier coatings by intense pulsed electron beam irradiation

In this paper, intense pulsed electron beam was used for the irradiation treatment of 6–8% Y2O3-stablized ZrO2 thermal barrier coating prepared by electron beam-physical vapor deposition to achieve the “sealing” of columnar crystals, thus improving their thermal insulation properties and high temperature oxidation resistance. The electron beam parameters used were: pulse duration 200μs, electron voltage 15kV, energy density 3, 5, 8, 15, 20J/cm2, and pulsed numbers 30. 1050°C cyclic oxidation and static oxidation experiments were used for the research on oxidation resistance of the coatings. When the energy density of the electron beam was larger than 8J/cm2, ZrO2 ceramic coating surface was fully re-melted and became smooth, dense and shiny. The coating changed into a smooth polycrystalline structure, thus achieving the “sealing” effect of the columnar crystals. After irradiations with the energy density of 8–15J/cm2, the thermally grown oxide coating thickness decreased significantly in comparison with non-irradiated coatings, showing that the re-melted coating improved the oxidation resistance of the coatings. The results of thermal diffusivity test by laser flash method showed that the thermal diffusion rate of the irradiated coating was lower than that of the coating without irradiation treatment, and the thermal insulation performance of irradiated coating was improved.

Structure, phase composition and mechanical properties of hard alloy treated by intense pulsed electron beams

Phase and structural changes in surface layers of WC–TiC–Co hard alloy treated by intense pulsed electron beams (IPEB) with electron energy of 20kV are studied. IPEB energy density absorbed by surface layer was 10–80J/cm2, pulse duration was 100–200μs. IPEB action with energy density of 30–80J/cm2 results in the formation of tungsten-supersaturated solid solution (Ti,W)C and transformation WC→W2C caused by melting of surface layers and their subsequent rapid quenching from liquid. Electron beam treatment leads to the formation of layered structure. Changes of structure and phase composition result in the increase of surface microhardness in 1.5–3 times and in the reduction of friction coefficient in 2–3.5 times.

In-Situ Diagnostics of the Development of Surface Waviness due to Treatment with an Intense Pulsed Electron Beam

Metal surfaces treated with pulsed electron beams having a power density of some MW/cm show a wavelike surface after solidification. For several applications, the waviness of the surface-modified layers has to be limited and, more importantly, controlled. Therefore, the development of such treatment-induced roughness is investigated systematically. Timeand space-resolved imaging of the target surface and measurement of the intensity modulation of a reflected laser beam are the diagnostic tools applied to evaluate the origin and development of the roughness during melting and solidification. The intensity modulation measurements of the reflected laser beam are performed using a HeNe-laser (632.8 nm) in normal reflection. A streak camera (Hamamatsu C7700) with high dynamic range is used, as well as a framing camera by PCO Imaging. This allows the time evolution to be measured and the target surface to be visualized with high spatial resolution. Metals with significantly different physical (paramagnetic and diamagnetic) and thermodynamic properties, like Ti, Ta, stainless steel, Al, Ag, and Au, are investigated in these experiments. The results indicate that the surface waviness mainly depends on the physical and the thermodynamic properties of the target materials and that the electron beam parameters play only a secondary role.

Surface modification/alloying using intense pulsed electron beam as a tool for improving the corrosion resistance of steels exposed to heavy liquid metals

The alloying of steel surface with aluminum (Al) using Microsecond-pulsed Intense Electron Beams (MIEB-Al) was developed and optimized in order to be used for improving the corrosion resistance of the 316, 1.4970 and T91 steels, exposed to liquid Pb and Pb–Bi-eutectic. The procedure consists in two steps: (i) coating the steel surface with Al or an Al-containing alloy layer and (ii) melting the coating layer and the steel surface layer using intense pulsed electron beam. In order to cover the steel surface with an homogeneous and crack-free Al-alloyed layer, the following experimental conditions are required: Al coating thickness range 5–10 μm, electron kinetic energy 120 keV; pulse duration 30 μs; energy density 40–45 J/cm 2; number of pulses 2–3. Using the mentioned procedure, the corrosion resistance of the 316, T91 and 1.4970 steels, exposed to Pb and Pb–Bi-eutectic with different oxygen concentrations and under different temperatures, was considerably improved due to the formation of a thin alumina layer (which thickness is lower than 1 μm for all the tested temperatures and durations) acting as an anti-corrosion barrier.

K -line spectra from tungsten heated by an intense pulsed electron beam

The plasma-filled rod-pinch diode (PFRP) is an intense source of x-rays ideal for radiography of dense objects. In the PRFP megavoltage electrons from a pulsed discharge concentrate at the pointed end of a 1 mm diameter tapered tungsten rod. Ionization of this plasma might increase the energy of tungsten's Kα(1) fluorescence line, at 59.3182 keV, enough for the difference to be observed by a high-resolution Cauchois transmission crystal spectrograph. When the PFRP's intense hard bremsstrahlung is suppressed by the proper shielding, such an instrument gives excellent fluorescence spectra, albeit with as yet insufficient resolution to see any effect of tungsten's ionization. Higher resolution is possible with various straightforward upgrades that are feasible thanks to the radiation's high intensity.