High Power Density Electron Beam Research Articles

A study on multi-hole machining of high-power density electron beam using a vaporized amplification sheet

Recently, electron beam machining technology has been used in various ways depending on the industrial field. It is used in technologies in the fields of shipbuilding, aerospace, and transportation. In the case of the existing electron beam machining technology, a technology for welding or joining two materials was proposed. In this paper, in order to perform electron beam drilling, a multi-hole is created by increasing the instantaneous vaporization pressure during electron beam machining through a vaporized amplification sheet. A vaporized amplification sheet was prepared for electron beam drilling. The vaporized amplification sheet was made of a 1:3.25 combination of silicone and brass powder. Also, in order to bond the produced vaporized amplification sheet to the SUS 304 stainless steel, a primer was applied on the surface of the metal material to firmly bond the two materials with different properties. If the bonding is weak, the effectiveness decreases due to pressure leakage during electron beam machining. Multi-holes were processed using the fabricated material to fix an acceleration voltage of 120 kV and a current of 12 mA. Also, to compare the multi-hole shape and the processing result, the comparison was performed according to the exposure time of the electron beam. The lower the exposure time, the more fine holes were secured, and as the exposure time increased, the molten pool phenomenon occurred, and processing was not performed in the experimental results.

A Study on Proposal of E-Beam Drilling Machining Criterion by Using on Vaporized Amplification Sheets in a High-Power Density Electron Beam.

As the consumer market in the mold, automation and aerospace industries grows, the demand for laser machining using on electron beam drilling. To enhance the machinability and productivity of the e-beam (electron beam), we want to develop a vaporized amplification sheet. The e-beam was used to mainly utilize for polishing, finishing, welding, a lithography process etc. However, the electron beam drilling machine does not develop in the country because it is difficult to make high power density and vaporized amplification sheets. The vaporized amplification sheets with fine particles are one of the essential factors and decided the quality of machined micro holes according to the macromolecule. So, this paper considers the preparation process of vaporized amplification sheets and the analysis of macromolecule for improving the electron beam processability and machinability efficiency. Also, we analyzed process conditions for the optimization of the electron beam machining process.

Narrow gap laser welding for potential nuclear pressure vessel manufacture

High power density electron beam and laser beam welding show their unique advantages in the welding of thick-section steels for potential nuclear pressure vessel manufacture. Compared with traditional submerged arc welding or newly developed narrow-gap submerged arc welding, electron beam welding and laser beam welding techniques offer high welding speeds, low heat inputs, lower levels of residual stresses and distortion, while consuming less filler material and power. As a part of the new nuclear manufacturing EPSRC Program, this study aimed to develop narrow gap laser welding procedures and parameters for joining 30–130 mm thick ferritic steels for potential application to pressure vessel manufacture in civil nuclear power plants. The results showed that high quality welded joints in 30 mm thick steels had been achieved with a combination of an autogenous root pass and multipass narrow gap (4–5 mm parallel grooves) welding with a defocused laser beam welding and filler wire addition, at laser powers of 7.5–8 kW, a welding velocity of 0.4 m/min, a diameter of the laser spot of 6 mm, and wire feed rates of 4–6 m/min. The results also showed that cracking, lack of sidewall fusion, and porosity were the main defects in multiple pass narrow gap laser welds in thick-section ferritic steels if the welding parameters were not optimized. The microhardness of the multipass weld was lower than that of the autogenous weld as tempered martensite was achieved in multipass welding.

Investigation of Point Defects Modification in Silicon Dioxide by Cathodoluminescence

The aim of this work is study of point defects modification in silicon dioxide by a high power density electron beam. In this work we used the method which allows to estimate quantitative content of luminescent point defects by dependence of cathodoluminescence on current density. Content of point defects was evaluated and changing of point defect content in silicon dioxide under electron beam was assessed. It is shown that content of defect connected with silicon deficit decreases whereas content of defect connected with oxygen deficit increases. The model of point defects transformation was suggested on the basis of these results.

Silicon nanoclusters formation in silicon dioxide by high power density electron beam

Silicon nanoclusters formation in silicon dioxide by high power density electron beam

Silicon nanoclusters formation in silicon dioxide by high power density electron beam

Abstract New method of silicon nanoclusters growth was proposed. Silicon nanoclusters are formed in silicon dioxide under high power density electron beam irradiation. The irradiated region of SiO 2 is overheating due to low heatconductivity. The temperature of overheating is depended on electron current density. It was estimated by Monte-Carlo method. This work was devoted to study of nanoclusters formation at different electron beam power density.

Study of ion diffusion in superionic crystals by EPMA and local CL

In this work the effect of ionic diffusion was studied in crystals AgI, HgI 2 and heterostructure Ag 2Hg 4I, obtained by a solid state chemical reaction (SSCR). The main aim was to characterize the structure of AgI–Ag 2HgI 4–HgI 2 p–n heterojunction and study the influence of a high power density electron beam on the ionic diffusion rate in this system. All structures were examined by electron probe microanalysis (EPMA) and local cathodoluminescence (CL). Dependence of elemental distribution and CL spectra on the p–n junction distance was revealed. Diffusion of Ag + ions was observed both in AgI crystals and through the interface of Ag 2HgI 4–HgI 2 in HgI 2 crystals.

Effect of periscope reflecting mirror on uncertainty of measured temperature of an electron beam heated metal vapor source

The temperature of the hot zone created by impact of a high power density electron beam (e-beam) needs to be monitored for reasons concerning process evaluation and safety. In high throughput e-beam evaporators, direct line of sight viewing of the hot zone using an optical pyrometer on a continuous basis is ruled out due to opacity introduced by rapid coating of the vacuum windows within a few seconds. An alternative that permits continuous visual monitoring relies on a periscopic arrangement that makes use of process generated thin film mirror formed by deposition of evaporating metal atoms. This paper discusses the additional error introduced by the thin film mirror during this type of monitoring arrangement for the case when a two-color pyrometer is used as temperature sensor. The dominant factors, namely temperature, pressure and reactivity of metal being evaporated, which affect the measured temperature are found and their effects are confirmed through our experimental data. It is shown that due to dynamically changing spectral reflectivity of the thin film mirror, the additional error in measured temperature could be in the range of ∼0–35% of the value recorded by direct viewing method depending upon the above parameters. Finally, as an alternative, we propose a novel method and show through calculations that this method avoids errors experienced in the periscopic method and yet allows extended continuous monitoring time.

Calculation of the temperature during electron pulse annealing of silicon

High power density electron beams offer new opportunities for studies of epitaxial growth of semiconductor materials. Assuming that the mechanism of epitaxial growth can be understood as a surface melting followed by supercooling regrowth, the heat flow equation has been applied to calculate the temperature reached after an electron beam pulse of power density between 0.5–2 J/cm2. Comparison with laser annealing is made.

電子ビームによる金属箔の穴あけ

In electron beam drilling, accelerating voltages in the range of several tens of kV to 150 kV are practically used. In these voltages, electrons can penetrate about ten to several tens of microns into solid metal. Electron penetration range, therefore, is an important factor for drilling characteristics. In the present paper, the drilling characteristics of metal foils are discussed on the basis of energy loss of electron beams in the foil, heat conduction and experimental data obtained by 100 kV electron beams. As a result, in the case of foils thinner than the electron penetration range it became clear that in spite of the fact that copper has a higher thermal conductivity and a higher melting point than aluminum, copper foil can be more easily drilled than aluminum foil, i. e., the drilling characteristics depend not only on the thermal properties but also on the relation between foil thickness and electron penetration range. Moreover, using saturation hole size drilled in thinner foil than the electron penetration range, a new determination method of beam size of high power density electron beam is proposed. The value obtained by this method agrees well with the value obtained by the conventional method.

A contribution to explain the deep penetration of high-power density electron beams in metals

A contribution to explain the deep penetration of high-power density electron beams in metals

アルミニウム箔の穴あけとパワー密度分布

For electron beam drilling, a high power density beam must be used. However, decision of distribution of high power density electron beam is very difficult, because such a beam can easily drill a metal target. In the present paper, a method for deciding the distribution of power density is discussed. Namely, the distribution of temperature rise is calculated by assuming that the power density obeys the normal distribution, of which standard deviation is different with respect to x-axis and y-axis respectively and that transforming the conduction of heat to the two dimensional problem by using a thin aluminum foil, of which thickness is smaller than the range of electron penetration. Moreover, the foil is drilled by pulsed beam. From the experimental dimensions of hole, the pulse duration and the calculated temperature rise, the distribution of power density is estimated.

Artificial fulgurites

A high power density electron beam can produce artificial fulgurites in a bed of quartzose sand. The volume of each fulgurite is nearly linearly proportional to the total energy deposited by the electron beam. We suggest that a similar relationship could hold for natural fulgurites, thus allowing the energy deposited by certain ligthning strokes to be determined directly by measuring the volumes of the fulgurites they produce.

単一パルス高パワー密度電子ビームによる金属の穴あけ加工

It has been said that the high power density electron beam drilling is performed by the heating inside the target which is caused by the phenomenon that the high potential electrons penetrate into target. However, from the view-points of heat conduction theory and dynamic theory it has not been made clear. In this paper, the mechanism of high power density electron beam drilling of metals is discussed on the bases of heat conduction and force balance between vapour pressure and shrinking pressure due to surface tension. Namely, the critical temperature of generation of molten metal removal and the drilling speed are estimated. The estimated speed coincides with the experimental value. Moreover, the phenomenon of saturation of drilled depth is explained rationally.

High Power Density Electron Beam Bombardment Type Ion Source with Hot Hollow Electron Cathode Using Static Electron Lens

High Power Density Electron Beam Bombardment Type Ion Source with Hot Hollow Electron Cathode Using Static Electron Lens

A New Electron Bombardment Type Ion Gun for High Brightness Metal Ion Beam

If a metal target is bombarded by the high power density electron beam, the target material are made to evaporate and the evaporated atoms will be ionized by collision with the incident electrons. As these ions have lower energy than several electron volts, the incident electron beam can trap these ions in the potential valley of space charges. The trapped ions are diffused and accelerated toward the electron cathode which have the hole in the centre (in practice the spirally wound tantalum wire was used). And the ions are taken out through this cathode hole.Ion beams got by above process have fine diameter and low aperture angle, then the brightness of ion beam become higher in itself though the total ion current is not so high.Several metals as Cr, Si, Mg-Al alloy and others were used as targets. In the case of Mg-Al target the values of normalized brightness of the ion beam reached the order of 2×10-94.6×1010 A/m2 ·rad2. And the masses of ion beam components were analyzed by using the circular pole magnet.This ion gun will be usable as a fine metal ion source and a mass analyzer of target material.

高動力密度電子ビームの金属への侵入

The high power density electron beam can produce a narrow and deep melting in metal. This phenomenon is caused by the deep penetration of electron beam into metal. In this paper the mechanism of this deep penetration is discussed. Namely, the X-ray generated by collision of electron with metal is measured by scintillation counter and X-ray film and then the new model about the penetration path of electron beam originated from the experimental data of X-ray and the theoretical considerations is proposed. Moreover, the fluctuation of the penetration path is discussed theoretically and the change of the shape of molten zone with respect to metals can be explained.