High Voltage Electron Beam Research Articles

Development of a high-voltage power supply with ultra-low ripple of beam current on electron beam gun.

Electron beam guns with grid-controlled electrodes and hot-cathodes are widely used in accelerator physics facilities, high-voltage electron beam welding machines, electron beam 3D additive manufacturing, x-ray sources, etc. The ripple of electron beam current is one of the most critical factors affecting beam quality, and the electron beam current ripple is generally more than 2% with traditional circuit topology. This paper presents the expression for beam current, high voltage, and bias voltage derived from experimental data on a certain electron beam gun. Furthermore, the main causes of affecting beam current ripple are analyzed, and a novel circuit topology is proposed. According to the ISO14744, Welding-Acceptance inspection of electron beam welding machines, a Faraday cup is used to collect the beam from the electron beam gun. In this paper, the ripple of the beam current of the electron gun driven by the traditional and proposed circuits is tested, respectively. The experimental results show that the ripple of beam current of the novel circuit topology can be achieved to within ±0.18% when the voltage is 150kV and the beam current is 33 mA, lower than 10 percent of that of the traditional power supply. The stability of beam current is better than 5 μA at 150kV and 3.3 mA.

Rapid synthesis of ultra-wear-resistant nanocrystallite stainless steel via electron beam direct irradiation

Surface nanocrystallization is a highly effective approach for enhancing the surface wear resistance of stainless steel. However, the attainment of fast nanocrystallization on stainless steel surfaces remains a significant obstacle. Thus, a novel form for high-voltage electron beam radiation with a rapid response time of 50 ms is proposed to break through this bottleneck. The results revealed the presence of significant quantities of nanocrystals and an amorphous structure in the modified layer of stainless-steel surfaces. A large number of dislocation lines resulted in an interplane distance increase in the (110) planes of Fe-Cr. In addition, the dislocation walls can inhibit the growth of the crystal, contributing to a remarkable enhancement in their surface wear resistance. Significantly, the wear volume of the modified layer decreased from 0.0124 mm3 to 0.0013 mm3, a remarkable reduction of 90 % compared to the initial state due to surface nanocrystallization, dispersion strengthening, and dislocation walls. This study provides novel concepts for the production of surface nanocrystals in ultra-wear-resistant stainless steel.

Enhanced EBAC localization of gate oxide defects after high voltage electron beam irradiation

Electron Beam (EB) irradiation with high acceleration voltage is widely reported to have resulted in significant degradation on transistor parametric performances. Therefore, high voltage EB should be avoided during nanoprobing transistor device characterization. There are many studies that mainly emphasize on prevention, cause, and consequences of such detrimental effects but rarely focus on the exploitation of these EB effects. In fact, high voltage EB could possibly leverage to enhance nanoscale fault isolation. In this paper, it was discovered that high voltage EB effects can be utilized to enhance the EBAC localization of Gate Oxide breakdown defects. Three successful case studies are described to demonstrate these enhancements on P-type and N-type MOSFET gate oxide defect isolation through the suppression on the gate leakage by high voltage EB induced charge trapping mechanism.

Preliminary Experimental Research on Split-Cathode-Fed Relativistic Magnetron With Bidirectional Emission Structure

Simulations and experiments of an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}$ </tex-math></inline-formula> -band TEM-output relativistic magnetron (RM) driven by split cathode (SC) are proposed. In the previous researches on SC, as a result of the space-charge-screening effect of squeeze-state electrons accumulated nearby the emission surface, the diode current is limited, which finally results in low output power. To improve the output performance, a bidirectional emission SC (BSC) is introduced. Experimental results on EPA-90 high-voltage electron beam accelerator demonstrate that when the voltage is around 480 kV and the axial magnetic field is 0.49 T, comparing with a conventional unidirectional emission SC, the output power can be enhanced from 124 to 400 MW by adding an extra downstream emitter. This work lays a foundation for further researches to make the SC-fed RM more practical.

Characterization of Extracellular Vesicles by Transmission Electron Microscopy and Immunolabeling Electron Microscopy.

Transmission electron microscopy (TEM) is currently the only method that enables the observation of extracellular vesicles (EVs) at a nanometer scale. Direct visualization of the whole content of EV preparation provides not only crucial insights on the morphology of EVs but also an objective evaluation of the content and purity of the preparation. Coupled to immunogold labeling, TEM allows the detection and association of proteins at the surface of EVs. In these techniques, EVs are deposited on grids and are chemically immobilized and contrasted to withstand a high-voltage electron beam. Under high vacuum, the electron beam hits the sample and the electrons that scatter forward are collected to form an image. Here, we describe the steps needed to observe EVs by classical TEM and the extra steps required to label proteins through immunolabeling electron microscopy (IEM).

High-aspect nano-groove fabrication in thick film resists using 150-kV high acceleration voltage electron beam lithography

High acceleration voltage (150 kV) electron beam lithography is applied to two types of thick film resists with different contrasts (γ). When using 1.6-μm thick high-γ resist, the lowest width discrepancy, 35 nm, was observed at 150 kV in the cross-sectional shape, which was almost vertical. At 50 kV, the discrepancy was more than four times greater than the width at 150 kV. The 50-kV cross-sections were drop shaped. The maximum line widths were similar for both resists, while the top line widths were smaller for the high-γ resist than for the low- γ resist. In addition, Monte Carlo simulation results were consistent with the experimental values, especially at 150 kV.

Design of 325 MHz RF grid-controlled high voltage thermionic cathode electron gun

The electron gun with high repetition rate and high average current has a very wide range of applications. This paper presents the design of a microwave grid-controlled high-voltage thermionic electron gun working in CW mode with a bunch repetition rate of 325 MHz and elaborates the experimental principles of this kind of electron guns. Firstly, simulation software EGUN, POISSON (Poisson Superfish) and GPT (General Particle Tracer) are used to accomplish the structure design of a300kV high-voltage DC electron gun and beam dynamics verification.Secondly, to feed the microwave into the gap between the cathode and the grid of the electron gunefficiently, design of a power supply with a scheme of impedance matching from the radio frequency power source to the cathode is completed.Accordingly, a 325 MHz dual-mode coaxial power supply device is designed, and its feasibility is verified and analyzed..

Plasma chemical reactions initiation in supersonic jets by a high-voltage electron beam

The results of the study of processes occurring in supersonic flows of gas mixtures under the influence of high voltage electron beam are presented. The research was performed on the gas-dynamic complex of experimental installations located in the Department of Applied Physics of Novosibirsk State University. Spectral methods and molecular beam mass spectrometry were used to diagnose the processes. A significant difference in the clustered argon mass spectra was found in comparison of spectrum recorded during ionization by a quadrupole mass spectrometer own ionizer and spectrum obtained with the transport of ions formed by an electron beam in the jet through a skimmer to the mass spectrometer detector (without using an ionizer of spectrometer). The second variant of gas flow ionization presents the possibility of registering the mass spectrum of a hydrocarbon series with features indicating the occurrence of heavier hydrocarbons in the jet. The mechanism of intracluster energy exchange with the transfer of excitation initiated by electrons with subsequent intense radiation at certain wavelengths of a neutral argon atom was detected and identified.

On the similarity of traditional and cluster jets during supersonic gas outflow into flooded space

Annotation. The visualization of gas flows expanding from supersonic nozzles into flooded space under the cluster formation conditions is considered. The technique of exciting the supersonic flow by a well-focused high-voltage electron beam is applied in conjunction with the scanning equipment for the gas objects. The reasons for the secondary cluster jet formation in a flow of easily condensing gases are discussed. A comparison is made between the formation of a traditional spindle-shaped jet and a secondary cluster one. The measurement results of the diameters of the traditional and cluster jets in maximum sections, obtained by the photometry method, are presented. It is shown that for the characteristic sizes of cluster jets of condensing gases, the dependence on parameters proposed by Sherman and Ashkenas is applicable in the entire range of the studied stagnation and background pressures. The similarity of the formation processes of traditional monomeric jets and secondary cluster jets under the conditions of developed condensation of the initial supersonic flow is supposed.

Causes of the Glow of the Anomalous Secondary Flow in Supersonic Clustered Jets Excited by a High-Voltage Electron Beam

The role of clustered particles in the formation of a secondary flow (“wake”) upon the outflow of gas into a rarefied medium in condensation modes is found out. The boundaries of the “wake” are found by comparing the spectral and photometric measurements. Possible mechanisms of the initiation of its glow are considered. The role of the energy exchange of clusters with background gas in the afterglow of the “wake” is established. The wavelengths and corresponding transitions in the neutral (Ar-I) and singly ionized (Ar-II) argon atoms, which cause the anomalous glow, are determined. The lifetimes of particles in the excited state in the central part and on the periphery of the clustered flow are found. The effect of condensation on the penetration of the background gas into the primary traditional supersonic jet and into the “wake” zone is found.

Энергосберегающая методика изучения физической модели высоковольтного инвертора на основе электронно-лучевого клапана

The schemes of inverters applied in static reactive power compensators (SRPC) are as a rule developed with the use of power semiconductor devices (PSD); however, attempts to develop industry-grade prototypes of high-voltage inverters on the basis of serially produced vacuum-tube devices (VTD) are also made. High-voltage electron beam valves (EBV), which feature—owing to beam recovery at the anode — the minimum possible voltage drop across the anode-cathode section in the conductive state among the VTDs and a high steepness of the impulse front and trailing edges in comparison with PSDs, seem to be promising for such applications. An EBV was simulated in the EWB circuit engineering computer program environment to determine the minimum permissible load resistance at which the EBV has the maximum electrical efficiency up to 0.99. To determine whether it is advisable to construct such inverters, it is necessary to conduct not only theoretical, but also experimental investigations on physical models using dedicated test benches. A high-voltage energy-saving bench for testing EBVs operating within the SRPC circuit in an inverter mode has been developed. The bench takes power supply from the 3x380 V, 50 Hz network. The bench comprises a three-phase high-voltage transformer, using which the power supply voltage can be increased to a 40 kV level. This voltage is rectified according to the Larionov bridge scheme, and, owing to an artificial midpoint, the 0 to +20 kV and 0 to -20 kV voltages with the maximum current up to 1 A are obtained. The voltage amplitude can be smoothly varied using a three-phase electromechanical regulator installed in the high-voltage transformer primary winding. A 50 Hz sine-wave voltage is produced in the inverter mode by means of pulse-width modulation (PWM) with a clock frequency smoothly variable in the 1...3 kHz range and is applied to a water equivalent of load. To increase the bench power level during the test and achieve energy saving, a gating logic device (GLD) was introduced, which allows the EBV control system to operate in an intermittent PWM generation mode. The GLD produces pulses using which three cycles of a 50 Hz sine-wave voltage (with the total duration equal to 60 ms) repeating at approximately 1.2 s intervals are generated. The use of the GLD producing packs of control pulses makes it possible to study the EBV operation modes on the bench at a short-term power of up to 200 kW in pulse-periodic mode, which is significantly (by 10.20 times) higher than the average power of the bench constant-voltage network power supply source. The GLD output voltage waveforms and the load voltage and current front and trailing edge waveforms are given.

Features of using traditional diagnostic tools for recording supersonic jets of rarefied gases in flows with clusters

Features of the formation of supersonic underexpanded jets in condensation, as well as measurements in such jets by electron-beam and molecular-beam methods are considered. It is shown that the clusters in the flow can change both the geometry and the structure of the supersonic jets. It is determined that the readings of the mass analyzer used as a detector of a narrowly directed molecular beam depend to a large extent on the size of the clusters and the value of the detector’s solid angle. The examples which compare the traditional method of mass spectrometry with ionization and a new method ionization by high-voltage electron beam with the subsequent transport of ions to the mass spectrometer detector with its own turned-off ionization block illustrate changes in the detected clusters.

Alloying effect of Ti-6Al-4V on composite of 321 stainless steel fabricated by electron beam additive manufacturing

For the present significant progress has been made in understanding additive manufacturing processes Additive manufacturing techniques such as selective laser melting and laser-based directed energy deposition are widely used, but in comparison, electron-beam melting offers two unique advantages that are particularly important for titanium alloys: a high-vacuum medium and a preheating capacity for both substrate and feed material. This work describes experimental studies of a component built from 321 stainless steel and Ti-6Al-4V. The coating was formed through deposition of a wire with the use of a high-voltage electron beam in the high-vacuum medium. Two materials of deposition on the substrate were carried out in this study. As a result, 321 stainless steel composite coating can successfully form surface with gradient microstructure during EBAM cladding process. At Ti-6Al-4V of compositions was cracked, which led to the destruction of the top of the sample. The presence the intermetallic compounds of the top of the sample adversely affected of the composite that cracking occurred in the material.

Mass spectrometric study of gas clusters by a high-voltage electron beam

The possibility of using a high-voltage electron beam as an ionizer of supersonic clusters of argon and methane gas jets in molecular beam mass spectrometry are investigated. The formation of clusters occurs when the gas flows through the supersonic nozzle into the vacuum. The ionization of the flow is carried out by electrons with an energy of 10 keV. The diaphragm (skimmer) from jet forms a molecular beam, which passes into the input aperture of the mass spectrometer through the sections of the installation. The ion focusing is provided with the use of collimating diaphragms as electrostatic lenses. A quadrupole mass spectrometer is used as a cluster ion analyzer. The obtained mass spectra are compares with the signals observes with the usage of traditional molecular beam mass spectrometry, in which ionization of particles occurs in the electron analyzer’s own block with energies of the 100 eV order. The justification of the standard approach shortcomings is proposed. Obtained data shows chemical reactions in hydrocarbons and cluster magic numbers for argon, obtained result is consistent with known data.

Structure and mechanical properties of a two-layered material produced by the E-beam surfacing of Ta and Nb on the titanium base after multiple rolling

The study has been conducted in line with the current approach to investigation of materials obtained by considerably deep surface alloying of the titanium substrate with Ta, Nb, and Zr. The thickness of the resulting alloyed layer was equal to 2 mm. The coating was formed through weld deposition of a powder with the use of a high-voltage electron beam in the air. It has been lately demonstrated that manufactured such a way alloyed layers possess corrosion resistance which is significantly higher than the resistance of titanium substrates. It has already been shown that such two-layered materials are weldable. The study objective is to investigate the feasibility of rolling for necking the sheets with the Ti-Ta-Nb anticorrosion coating with further fourfold decrease in their thickness. The research is also aimed at investigation of the material properties after rolling. Anticorrosion layers were formed both on CP-titanium and on VT14 (Ti-4Al-3Mo–1 V) durable titanium alloy. The results of chemical composition determination, structure examination, X-ray phase analysis and mechanical properties observations (including bending properties of the alloyed layers) are presented in the paper. The combination of welding, rolling, and bending enables the manufacture of corrosion-resistant vessels and process pipes which are made from the developed material and find technological application.

The technology of forming Ti-Nb layers on the surface of titanium alloy plates using a high-voltage electron beam output into a protective argon medium

The structure and properties of layers obtained by electron-beam melting of titanium-niobium powder mixtures in a protective argon medium are studied in the work. The method allows cladding traces 16.5 … 17.5 mm wide with a maximum thickness of 3.5 … 4.5 mm. The concentration of niobium in the formed surface layers is 6.6 and 13.8%. The cladded material has a predominantly lamellar structure. The production of layers in the protective medium of argon makes it possible to increase the microhardness level, as well as the corrosion resistance of titanium in boiling solutions of nitric and sulfuric acid.

Low-voltage-exposure-enabled hydrogen silsesquioxane bilayer-like process for three-dimensional nanofabrication

We report a bilayer-like electron-beam lithographic process to obtain three-dimensional (3D) nanostructures by using only a single hydrogen silsesquioxane (HSQ) resist layer. The process utilizes the short penetration depth of low-energy (1.5 keV) electron irradiation to first obtain a partially cross-linked HSQ top layer and then uses a high-voltage electron beam (30 keV) to obtain self-aligned undercut (e.g. mushroom-shaped) and freestanding HSQ nanostructures. Based on the well-defined 3D resist patterns, 3D metallic nanostructures were directly fabricated with high fidelity by just depositing a metallic layer. As an example, Ag-coated mushroom-shaped nanostructures were fabricated, which showed lower plasmon resonance damping compared to their planar counterparts. In addition, the undercut 3D nanostructures also enable more reliable lift-off in comparison with the planar nanostructures, with which high-quality silver nanohole arrays were fabricated which show distinct and extraordinary optical transmission in the visible range.

Ultrahigh charging of dust grains by the beam−plasma method for creating a compact neutron source

Generation of high-voltage high-current electron beams in a low-pressure (P = 0.1–1 Torr) gas discharge is studied experimentally as a function of the discharge voltage and the sort and pressure of the plasma-forming gas. The density of the plasma formed by a high-current electron beam is measured. Experiments on ultrahigh charging of targets exposed to a pulsed electron beam with an energy of up to 25 keV, an electron current density of higher than 1 A/cm2, a pulse duration of up to 1 μs, and a repetition rate of up to 1 kHz are described. A numerical model of ultrahigh charging of dust grains exposed to a high-energy electron beam is developed. The formation of high-energy positive ions in the field of negatively charged plane and spherical targets is calculated. The calculations performed for a pulse-periodic mode demonstrate the possibility of achieving neutron yields of higher than 106 s–1 cm–2 in the case of a plane target and about 109 s–1 in the case of 103 spherical targets, each with a radius of 250 μm.

A 0.14 THz relativistic coaxial overmoded surface wave oscillator with metamaterial slow wave structure

This paper presents a new kind of device for generating the high power terahertz wave by using a coaxial overmoded surface wave oscillator with metamaterial slow wave structure (SWS). A metallic metamaterial SWS is used to avoid the damage of the device driven by a high-voltage electron beam pulse. The overmoded structure is adopted to make it much easy to fabricate and assemble the whole device. The coaxial structure is used to suppress the mode competition in the overmoded device. Parameters of an electron beam and geometric structure are provided. Particle-in-cell simulation results show that the high power terahertz wave at the frequency of 0.14 THz is generated with the output power 255 MW and conversion efficiency about 21.3%.

Development of Power Supply for Inverter Electron Beam Welder Based on Zero-Voltage Switching Technology

In this paper, introduce the power supply for full-bridge inverter high frequency high voltage electron beam welder, applying PWM-Buck integrated circuit and zero-voltage switching technology and the control system. Getting continuously adjustable, stable over current and over voltage protection, and the regulator the accuracy requirements of output voltage from high voltage power supply, and improve the energy conversion efficiency of the system.