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In This paper we will introduce the process of design and manufacturing an electron accelerator with 10MeV energy and 100kW power as the first Iranian powerful industrial electron accelerator. This accelerator designed based on modeling of one of the most powerful industrial accelerator called Rhodotron. But the design of the accelerator in a way that can be localize by relying on domestic industries. So although it looks like a Rhodotron accelerator structure but has some different in design and manufacture of components, the results are satisfactory

Copyright of Metallophysics & Advanced Technologies / Metallofizika i Novejsie Tehnologii is the property of G.V. Kurdyumov Institute for Metal Physics, N.A.S.U and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Purpose: For scanning particle beam therapy, interference between scanning patterns and interfield organ motion may result in suboptimal dose within target volume. In this study, we developed a simple offline correction technique for uniform scanning proton beam (USPB) delivery to compensate for the interplay between scanning patterns and respiratory motion and demonstrate the effectiveness of our technique in treating liver cancer. Methods: The computed tomography (CT) and respiration data of two patients who had received stereotactic body radiotherapy for hepatocellular carcinoma were used. In the simulation, the relative beam weight delivered to each respiratory phase is calculated for each beam layer after treatment of each fraction. Respiratory phases with beam weights higher than 50% of the largest weight are considered "skipped phases" for the next fraction. For the following fraction, the beam trigger is regulated to prevent beam layers from starting irradiation in skipped phases by extending the interval between each layer. To calculate dose‐volume histogram (DVH), the dose of the target volume at end‐exhale (50% phase) was calculated as the sum of each energy layer, with consideration of displacement due to respiratory motion and relative beam weight delivered per respiratory phase. Results: For a single fraction, D1%, D99%, and V100% were 114%, 88%, and 32%, respectively, when 8 Gy/min of dose rate was simulated. Although these parameters were improved with multiple fractions, dosimetric inhomogeneity without motion management remained even at 30 fractions, with V100% 86.9% at 30 fractions. In contrast, the V100% values with adaptation were 96% and 98% at 20 and 30 fractions, respectively. We developed an offline correction technique for USPB therapy to compensate for the interplay effects between respiratory organ motion and USPB beam delivery. Conclusions: For liver tumor, this adaptive therapy technique showed significant improvement in dose uniformity even with fewer treatment fractions than normal USPB therapy. [ABSTRACT FROM AUTHOR]

Vigorously developing nuclear power is the main development direction of current renewable energy. In the nuclear environment, in order to avoid nuclear radiation damage to maintenance personnel and improve the efficiency of nuclear reaction, it is necessary and urgent to realize automatic replacement of vulnerable parts in the electron gun. As the key equipment for the generation and control of nuclear reactions in nuclear reactors, electron guns have been widely used in nuclear power plants of traveling wave reactors. However, the “high-voltage conductive ring” in electron guns is a vulnerable part. It is likely to cause nuclear reactor accidents when the vulnerable part is damaged. Automatic replacement of vulnerable parts is an important part of the entire maintenance equipment. Considering the entire maintenance equipment and the working environment, an innovative design process for vulnerable parts replacement is established. Under the guidance of the process, in order to ensure the continuity of a series of maintenance actions, the technical contradiction resolution theory is first used to conduct the overall analysis of the general direction to obtain the design layout. Then, the contradiction resolution theory and the object-field model analysis are utilized to get and improve the detailed design of the device mechanism. The theory of TRIZ can help us to get the overall mechanical structure design that meets the engineering requirements. The device is designed with a replacement part adjustment scheme to ensure the completion of the maintenance actions. Furthermore, the design provides a solution to the possible jamming phenomenon in the automatic maintenance process and achieves the maximum use efficiency of the storage and replacement of vulnerable parts. [ABSTRACT FROM AUTHOR]

The space-charge field at the cathode limits the current density extracted from particle sources such as photoinjectors. For a long time, the maximum current has been estimated by using the classical Child-Langmuir law, which is derived with an assumption inconsistent with the conditions of modern laser-driven electron guns. Here, we introduce a theoretical model that accurately accounts for space-charge effects in transversely confined particle beams emerging from photocathodes. The model enables us to (i) determine the maximum current density extractable from the photocathode for an arbitrary cathode radius, (ii) reveal its dependence on the transverse profile of the particle beam, and (iii) predict its upper limit for structured beams such as the ones produced by surface-plasmon resonance-enhanced photocathodes. [ABSTRACT FROM AUTHOR]

Abstract The AXSIS project (Attosecond X-ray Science: Imaging and Spectroscopy) aims to develop a THz-driven compact X-ray source for applications e.g. in chemistry and biology by using ultrafast coherent diffraction imaging and spectroscopy. The key components of AXSIS are the THz-driven electron gun and THz-driven dielectric loaded linear accelerator as well as an inverse Compton scattering scheme for the X-rays production. This paper is focused on the prototype of the THz-driven electron gun which is capable of accelerating electrons up to tens of keV. Such a gun was manufactured and tested at the test-stand at DESY. Due to variations in gun fabrication and generation of THz-fields the gun is not exactly operated at design parameters. Extended simulations have been performed to understand the experimentally observed performance of the gun. A detailed comparison between simulations and experimental measurements is presented in this paper. [ABSTRACT FROM AUTHOR]

Abstract The AWAKE collaboration prepares a proton driven plasma wakefield acceleration experiment using the SPS beam at CERN. A long proton bunch extracted from the SPS interacts with a high power laser and a 10 m long rubidium vapor plasma cell to create strong wakefields allowing sustained electron acceleration. The electron beam to probe these wakefields is created by an electron accelerator consisting of an rf-gun and a booster structure. This electron source should provide beams with intensities between 0.1 and 1 nC, bunch lengths between 0.3 and 3 ps and an emittance of the order of 2 mm mrad. The booster structure should accelerate the electrons to 16 MeV. The electron line includes a series of diagnostics (pepper-pot, BPMs, spectrometer, Faraday cup and screens) and an optical transfer line merges the electron beam with the proton beam on the same axis. The installation of the electron line started in early 2017 and the commissioning will take place at the end of 2017. The first phase of operation is called RUN1. After the long shutdown of LHC a second phase for AWAKE is planned starting 2021 called RUN2. In this phase the aim is to demonstrate the acceleration of high quality electron beams therefore a bunch length of the order of 100 fs rms is required corresponding to a fraction of the plasma wavelength. The AWAKE collaboration is studying the design of such an injector either based on classical rf-gun injectors or on laser wake-field acceleration. The focus for the RF accelerator is on a hybrid design using an S-band rf-gun and x-band bunching and acceleration cavities. The layout of the current and the future electron accelerator and transfer line, including the diagnostics will be presented. Highlights • Electron source for the AWAKE experiment at CERN. • Design of an ultra-short bunches electron source. • Optical and electrical diagnostics for the AWAKE experiment at CERN. [ABSTRACT FROM AUTHOR]

Abstract The concept of the electron multi-beam linear accelerator EVT invokes aspects of a two-beam accelerator. Here, effective transformation of several drive beams energy into the high-voltage accelerated beam energy takes place. It combines an RF generator and essentially an accelerator within the same vacuum envelope. Acceleration occurs in inductively-tuned cavities. The ratios between values of RF beam currents and their voltages are similar to ratios for an electric transformer that allows to designate this device as an Electron Voltage Transformer (EVT). The EVT accelerator properties prove to be true by the example of numerical simulations of two-stage EVT operating in S-band with a 60 kV gun and generating a 1 A, 4.5 MV beam at its output, having efficiency of 25% is presented. ©2001 Elsevier Science. All rights reserved. [ABSTRACT FROM AUTHOR]

Highlights • KoHLT-EB (Korea Heat Load Test facility with Electron Beam gun) is operated for the performance testing of PFCs in Korea. • Various tungsten mockups were fabricated by HIP (Hot Isostatic Pressing) and VPS (vacuum plasma spray) coating technique. • A thermal fatigue test was performed to validate manufacturing technology, thermo-hydraulic performance and design validation. Abstract KoHLT-EB (Korea Heat Load Test facility with Electron Beam gun) is operated for the performance qualification testing of the plasma facing components (PFC), ITER first wall (FW), ITER TBM (Test Blanket Module) FW, and DEMO PFCs in Korea. A thermal fatigue test shall be performed on the fabricated mockups to validate manufacturing technology, thermo-hydraulic performance and design validation using high heat load testing. The test parameters are defined along with numerically simulated conditions. For the high heat flux testing, various mockups were fabricated by each bonding technique, such as HIP (Hot Isostatic Pressing), vacuum plasma spray (VPS) coating technique. Each fabricated mockup was installed inside the vacuum chamber of KoHLT-EB, and thermo-hydraulic performance tests and thermal fatigue tests were performed to qualify the mockups specification and bonding techniques. [ABSTRACT FROM AUTHOR]

Abstract: The dynamics of the electron beam in a C-band linear accelerator, a bremsstrahlung source with a boundary energy switched between 2.5 MeV and 6 MeV, which is intended for stereotactic and three-dimensional conformal radiotherapy in static and rotational modes, was calculated. [ABSTRACT FROM AUTHOR]

Highlights • A new apparatus using a linear ion trap and pulsed electron gun was set-up. • The experimental system was prepared for optical cooling and detection of calcium ions. • The integral cross sections for electron impact ionization of calcium atoms were measured in the energy range from 16 to 160 eV. • The results are in good agreement with other available data sets. Abstract An apparatus for production of various atomic and molecular ions inside a linear Paul trap has been set up. The system applies a custom-made, low energy, pulsed electron gun to produce ions in electron impact process. Such ionization method can find some interesting possible applications such as derivation of ions inaccessible other ways, which can be used in molecular ion experiments. The technique allows also for determination of cross sections for various collisional processes. As a feasibility study, the apparatus was used for determination of ionization integral cross section of calcium in the 16-160 eV range of electron impact energy. The obtained cross section values are discussed and compared with existing data sets. [ABSTRACT FROM AUTHOR]

Here, we present an optical fiber-based electron gun designed for the ultrafast streaking of low-energy electron bunches. The temporal profile of the few tens of the picosecond long electron bunch composed of 200 electrons is well characterized using a customized streak camera. Detailed analysis reveals that the stretched optical trigger pulse owing to the dispersion effects inside the waveguide dominantly determines the temporal length of the low density electron bunch. This result illustrates the capability to control the observable time-window in the streak diffraction experiment by tailoring geometrical parameters of the fiber source and its coupling condition. With the electrostatic Einzel lens system integrated on the fiber-based cathode, we also demonstrate spatial focusing of the electron beam with the RMS spot size of 98 μm and imaging of the static low-energy electron diffraction pattern of monolayer graphene in the electron kinetic energy range of 1.0–2.0 keV. [ABSTRACT FROM AUTHOR]

An extended interaction frequency-locking oscillator based on carbon nanotube (CNT) cold cathode is proposed to overcome locked-frequency limits of the conventional oscillator. Compared with the conventional oscillators, the oscillation frequency is locked by a modulation electron beam, which can be obtained in a field emission CNT cold cathode electron gun. The frequency-locking signal does not enter the high-frequency (HF) system but imposes an additional HF electric field on the cathode surface by a microstrip structure, which consumes considerably less power to lock the oscillation frequency. A ladder structure extended interaction oscillator operating in 2π mode is numerically investigated by three-dimensional Particle-In-Cell simulation code. By analysing the impacts of different frequency-locking power on the locked ranges, the results show that the average output power of 30.6 W is achieved at 35.11 GHz when the frequency-locking power consumption is 460 mW. The 3-dB bandwidth of a frequency-locking region reaches 100 MHz. [ABSTRACT FROM AUTHOR]

Electrostatic deflection of electrons by a pair of charged metal plates was studied over a range of electron kinetic energies. This was achieved using an electron gun in a cathode-ray tube assembly powered by a variable high-voltage controller. A deflection voltage was applied across charged symmetrical metal plates to deflect an electron beam vertically, and tracked on the phosphor screen of the cathode-ray tube. The deflection plates were shaped to allow maximum deflection: the beginning half of each was parallel, while the end portion was tapered. Our experimental results confirmed a universal scaling relationship between the electron deflection, as measured by the deflection tangent, and the voltage ratio of deflection versus acceleration, within 2% uncertainty over the range of accelerating voltage between 248 V and 527 V. A proper geometric ratio of plate length over its separation was 3.41 which by conventional analysis without considering the fringe field, served as a scaling factor for beam deflection versus the voltage ratio of deflection and accelerating biases. Our study demonstrated that fringe fields contribute considerably to the electron beam deflection, both prior to and after it going through the charged region. By considering the effects of the fringe fields, our model analysis revealed that fringe fields contribute up to 20% of the electron deflection, accounting for experimental results within 2%. [ABSTRACT FROM AUTHOR]

The Hybrid Illinois Device for Research and Applications (HIDRA) is a toroidal fusion device at the University of Illinois at Urbana–Champaign, Urbana, IL, USA. HIDRA is the former WEGA stellarator that was operated at the Max Planck Institut für Plasmaphysik, Greifswald, Germany. The machine is a five-period, $l=2, m=5$ stellarator, with major radius $R_{0}=0.72$ m, and minor radius $a=0.19$ m. Initial heating is achieved with 2.45-GHz electron cyclotron resonance heating and an on-axis magnetic field of $B_{0}=0.087$ T that can go as high as $B_{0}=0.5$ T. HIDRA has the ability to operate as both a stellarator and a tokamak, initially operating in the stellarator mode. The focus of research on HIDRA will be doing dedicated studies on plasma-material interactions (PMIs) using the wealth of knowledge and experience at the Center for Plasma Material Interactions, Urbana, IL, USA. In early 2016, the first experiments were performed on HIDRA. This paper presents some of the first results obtained from the machine such as initial magnetic fields’ measurements and plasma discharges. It also shows the development of the control system being currently implemented and introduces HIDRA-materials analysis tool, the in situ PMI facility that will be mounted on HIDRA in the near future to further enhance the diagnostics and material testing experiments meant to be conducted on the machine. [ABSTRACT FROM AUTHOR]

A novel S-Band Micro-Pulse electron Gun (MPG) which works at the left crossover point energy E c I on the Secondary Electron Yield (SEY) curve was proposed. The working principles of the MPG were presented. The maximum output beam current limited by space charge effects and beam loading effects was investigated by theoretical analysis. The result shows that the maximum beam current is decided by the parameters of the MPG such as resonant frequency, cavity length, shunt impedance and the secondary emission property of the cathode and grid, having nothing to do with the power flowed into the cavity. The low shunt impedance and the low slope of the SEY curve can help increasing the maximum beam current. According to the principles, a MPG with the frequency of 2.856 GHz has been designed and constructed. The steady working state was achieved by using oxygen free copper and molybdenum grid with different transmission coefficient. It was found a good agreement between the analysis and the experiments. [ABSTRACT FROM AUTHOR]

This paper seeks to investigate the space flight dynamics of a rotating barbell Electric Sail (E-Sail). This E-Sail contains two 6U CubeSats connected to 8 km tethers joined at a central hub. The central hub is designed to be an insulator so that each tether can have differing voltages. An electron gun positively charges each tether which interacts with the solar wind to produce acceleration. If the voltage on each tether is different, the trajectory of the system can be altered. Flapping modes and tension spikes are found during many of these maneuvers and care must be taken to mitigate the magnitude of these oscillations. Using sinusoidal voltage inputs, it is possible to control the trajectory of this two-body E-Sail and propel the system to Near-Earth-Objects or even deep space. [ABSTRACT FROM AUTHOR]

This paper presents the results of a newly developed 2-D electron beam analyzing code (EBAC) and its capabilities. This finite element cylindrical axis-symmetric code tracks particles by the fourth-order Runge–Kutta method in the local coordinate of elements and calculates steady-state results for both particle trajectories and the emitted current under space-charge limited condition. Two analytical test cases, along with an experimental case are presented to validate the EBAC results. Some techniques have also been developed to augment the basic algorithm of gun codes, dealing with computation of both the emitted current and particle trajectories. These proposed techniques in EBAC have proven to be efficient for reducing convergence time of the basic steady-state algorithm in Pierce-type structures for producing rectilinear electron beam. [ABSTRACT FROM AUTHOR]

Traveling-wave tubes (TWTs) in broadband power-combining applications should have closely matched gain and phase to achieve high system-level efficiency. A gain- and phase-matched TWT operating over a frequency band of 7.5–18 GHz with a minimum output power of 60 W is currently under production at Teledyne e2v. The tube design is based on an existing mini-TWT that incorporates focus electrode switching gun, phase velocity tapered helix slow wave structure, single-stage depressed collector, subminiature A connector at the input, and threaded Neill–Concelman connector at the output. During development and production stages, a number of devices were manufactured and their performances were matched. In this paper, we have described gain- and phase-matching techniques of such devices. Experimental results of 132 matched devices have been collated that show a gain match within ±3 dB and phase match within ±15°. [ABSTRACT FROM AUTHOR]

An equivalent multisector analytical method is proposed for the high-frequency characteristics of the slow-wave structure (SWS) in an integrated three-helix traveling wave tube. The discrete unit in the SWS is divided into multiple regions, and every region is treated equivalently as a sector using the equal area method. The accuracy of the equivalent multisector structure is verified by comparing it with an equivalent circular structure and the original SWS in computer simulation technology (CST). The analytical solution for high-frequency characteristics of the equivalent multisector structure is obtained by using the tape-helix model and the infinite number of vanes model. The calculation result is obtained and compared with the CST simulation result to analyze the accuracy of the method. The maximum error for dispersion characteristics and coupling impedance is 5.3% and 6.1%, respectively, so the feasibility of the analytical method is verified. [ABSTRACT FROM AUTHOR]

High efficiency and broadband operation of a gyrotron traveling wave amplifier (gyro-TWA) require a high-quality electron beam with low-velocity spreads. The beam velocity spreads are mainly due to the differences of the electric and magnetic fields that the electrons withstand the electron gun. This paper investigates the possibility to decouple the design of electron gun geometry and the magnet system while still achieving optimal results, through a case study of designing a cusp electron gun for a W-band gyro-TWA. A global multiple-objective optimization routing was used to optimize the electron gun geometry for different predefined magnetic field profiles individually. Their results were compared and the properties of the required magnetic field profile are summarized. [ABSTRACT FROM AUTHOR]

The evaluation, design, and simulations of two different electron guns generating the beams for W-band second cyclotron harmonic gyro-TWTs forming a high-gain powerful amplifier cascade are presented. The optimum configurations of the systems creating nearly axis-encircling electron beams having velocity pitch-factor up to 1.5, voltage/current of 40 kV/0.5 A, and 100 kV/13 A with acceptable velocity spreads have been found and are presented. [ABSTRACT FROM AUTHOR]

There are many applications of electron beams in accelerator facilities: for electron coolers, electron lenses, and electron beam ion sources (EBIS) to mention a few. Most of these applications require magnetic compression of the electron beam to reduce the beam radius with the goal of either matching the circulating ion beam (electron lenses and electron coolers) or increasing the ionization capability for the production of highly charged ions (EBIS). The magnetic compression of the electron beam comes at a cost of increasing share of the transverse component of energy and therefore increased angles of the electron trajectories to the longitudinal axis. Considering the effect of the magnetic mirror, it is highly desirable to produce a laminar electron beam in the electron gun. The analysis of electron guns with different configurations is given in this paper with emphasis on generating laminar electron beams. [ABSTRACT FROM AUTHOR]

The results of electron-beam surfacing in air of protective coatings by a low-energy (120 keV) electron beam produced by an electron gun with a plasma emitter are presented. The gun is mounted on an industrial robotic manipulator KUKA, which allows the electron beam to be moved to the atmosphere along a given path without electromagnetic sweep. The combined (self-propagating high-temperature synthesis and electron-beam surfacing) method for obtaining coatings from reaction mixtures of TiO2: 2.1C and TiO2: 0.3Cr2O3: 3.3С is implemented using this setup. The optimum composition of the reaction mixtures and the deposition regimes are determined by thermodynamic modeling using the TERRA program. The obtained coatings with a thickness of 120-200 μm have a microhardness of 12 GPa. The coatings and the transition layer are established to have good heat resistance up to 900°C. Noticeable changes in the weight characteristics of coatings occur at above 1000°C. [ABSTRACT FROM AUTHOR]

This contribution presents the solution of technological aspects in mass production of die-cast aluminium alloys as well as the design of new modules necessary for successful dealing with production. The welded parts are made of near eutectic aluminium alloy AlSi10Mg(Fe) / EN AC-43400 by high pressure die-casting process. Materials by its chemical composition and narrow solidification range do not represents significant problem from weldability point of view. Major problem is material contamination caused by the die-casting process. Several procedures were proposed to eliminate the problem of reduced weldability. Except for technological problems this contribution presents the concept design of mass production welding machine which is based upon experiences of welding process optimization. Special attention is payed to design of welding machine modules such as discharge protection module and module for online monitoring and recording welding process parameters. Application of discharge protection module increase welding process stability and allow prolongation the electron gun maintenance time. Module for online monitoring and recording allows implementation of Quality Management processes required by automotive industry. [ABSTRACT FROM AUTHOR]

Generally, a standard bunching system is composed of a standing-wave (SW) pre-buncher (PB), a traveling-wave (TW) buncher (B) and a standard accelerating structure. In the industrial area, the bunching system is usually simplified by eliminating the PB and integrating the B and the standard accelerating structure together to form a β -varied accelerating structure. The beam capturing efficiency for this kind of simplified system is often worse than that for the standard one. The hybrid buncher (HB) has been proved to be a successful attempt to reduce the cost but preserve the beam quality as much as possible. Here we propose to exclusively simplify the standard bunching system by integrating the PB, the B and the standard accelerating structure together to form a Hybrid Bunching-accelerating Structure (HBaS). Compared to the standard bunching system, the one based on the HBaS is more compact, and the cost is lowered to the largest extent. With almost the same beam transportation efficiency ( ∼ 70%) from the electron gun to the linac exit, the peak-to-peak (p-to-p) beam energy spread and the 1 σ emittance of the linac with the HBaS are ∼ 20% and ∼ 60% bigger than those of the linac based on the split PB/B/standard accelerating structure system. Nonetheless, the proposed HBaS can be widely applied in the industrial linacs to greatly increase the beam capturing efficiency without fairly increasing the construction cost. [ABSTRACT FROM AUTHOR]

The current requirements from civil and commercial applications lead to the development of compact free-electron laser (FEL)-based terahertz (THz) radiation sources. A picosecond electron gun plays an important role in an FEL-THz facility and attracts significant attention, as machine performance is very sensitive to initial conditions. A novel thermionic gun with an external cathode (EC) and two independently tunable cavities (ITCs) has been found to be a promising alternative to conventional electron sources due to its remarkable characteristics, and correspondingly an FEL injector can achieve a balance between a compact layout and high brightness benefitting from the velocity bunching properties and RF focusing effects in the EC-ITC gun. Nevertheless, the EC-ITC gun has not been extensively examined as part of the FEL injector in the past years. In this regard, to fill this gap, a development focusing on the experimental setup of an FEL injector based on an EC-ITC gun is described in detail. Before assembly, dynamic beam simulations were performed to investigate the optimal mounting position for the Linac associated with the focusing coils, and a suitable radio-frequency (RF) system was established based on a power coupling design and allocation. The testing bench proved to be fully functional through basic experiments using typical diagnostic approaches for estimating primary parameters. Associated with dynamic beam calculations, a performance evaluation for an EC-ITC gun was established while providing indirect testing results for an FEL injector. [ABSTRACT FROM AUTHOR]

A triode-type cusp electron gun was optimized through numerical simulations for a W-band gyrotron traveling wave amplifier. An additional electrode in front of the cathode could switch the electron beam on and off instantly when its electric potential is properly biased. An optimal electron beam of current 1.7 A and a velocity ratio (alpha) of 1.12 with an alpha spread of ∼10.7% was achieved when the triode gun was operated at 40 kV. [ABSTRACT FROM AUTHOR]

Isotopic thin Samarium (Sm) targets of 150–200 μg/cm 2 thickness have been fabricated in high vacuum (HV) environment by thermal evaporation method on carbon (C) backing of 20–25 μg/cm 2 thickness at Inter University Accelerator Centre (IUAC), New Delhi. Salient features of the method used for fabrication of 144 , 154 Sm targets are enumerated below: • A very thin layer of C of thickness 5–10 μg/cm 2 has been evaporated on Sm using electron-gun bombardment technique. • The detailed fabrication procedure along with various challenges faced (peeling off, oxidizing nature of the target etc.) has been discussed in this article. • Energy dispersive X-ray fluorescence (EDXRF) has been used to access the purity, thickness and elemental composition of targets. There is no trace of high Z impurity present in the prepared targets. • These targets have been successfully used in three nuclear physics experiments using the National Array of Neutron Detectors (NAND), HYbrid Recoil Mass Analyzer (HYRA) and General Purpose Scattering chamber (GPSC) at IUAC, New Delhi. [ABSTRACT FROM AUTHOR]

We report details of an electron-ion coincidence apparatus, which has been developed for molecular-frame electron energy loss spectroscopy studies. The apparatus is mainly composed of a pulsed electron gun, an energy-dispersive electron spectrometer, and an ion momentum imaging spectrometer. Molecular-orientation dependence of the high-energy electron scattering cross section can be examined by conducting measurements of vector correlation between the momenta of the scattered electron and fragment ion. Background due to false coincidences is significantly reduced by introducing a pulsed electron beam and pulsing scheme of ion extraction. The experimental setup has been tested by measuring the inner-shell excitation of N2 at an incident electron energy of 1.5 keV and a scattering angle of 10.2°. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Machine Construction & Maintenance is the property of Institute for Sustainable Technologies - National Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The concept of a miniature transmission electron microscope (TEM) on chip is presented. This idea assumes manufacturing of a silicon-glass multilayer device that contains a miniature electron gun, an electron optics column integrated with a high vacuum micropump, and a sample microchamber with a detector. In this article the field emission cathode, utilizing carbon nanotubes (CNT), and an electron optics column with Einzel lens, made of silicon, are both presented. The elements are assembled with the use of a 3D printed polymer holder and tested in a vacuum chamber. Effective emission and focusing of the electron beam have been achieved. This is the first of many elements of the miniature MEMS (Micro-Electro-Mechanical System) transmission electron microscope that must be tested before the whole working system can be manufactured. [ABSTRACT FROM AUTHOR]

We studied mathematical models for degradation behaviors of current and voltage in electron guns especially using oxide cathodes. We found that the current and the voltage, I(t) and V(t), follow the stretched exponential decay in oxide cathodes. On this basis, we derived a general expression for the time-dependent current–voltage relation as I(t)=p(t)V(t)δ(t), where δ(t) is a time-dependent exponent and the perveance, p(t), is a function of δ(t). The exponent δ(t) indicates the deviation of the classical Child–Langmuir relation (I=pV3/2). This deviation is attributed to the gradual change of the electron gun geometry over time. [ABSTRACT FROM AUTHOR]

A two-stage ferroelectric electron gun is employed in a free-electron maser (FEM) oscillator experiment. This gun produces a pulsed electron beam of a 5-15 keV energy, ∼0.5 A current, and ∼3% energy spread. The FEM output microwave pulse train is coupled out with a 66 W peak power. The microwave frequency is tunable in the range of 2.9-3.3 GHz by varying the electron beam energy. The interaction mechanism is identified by a comparison to the known FEM tuning relation. The energy spread of the two-stage ferroelectric electron gun satisfies the FEM acceptance parameter in the microwave regime. [ABSTRACT FROM AUTHOR]

Electron Guns are considered as important and useful devices in electron scattering studies. So far, different models of these guns have been designed. In this paper, using the computational code SIMION- 8.0 3D we simulate a low energy electron gun which is appropriate for the electron collision process. This computational code may be used to correct the canonical properties of electrostatic lenses and also to calculate the imposed voltages on the optical components of the electron gun. Moreover, by applying this code the location and diameter of all the apertures (electrodes) and also the tracing of the electron beams through the electrostatic lenses can be determined. The designed electron gun system accelerates and focuses the electrons leaving a thermionic emitter to an interaction domain (target) in a wide range of variable final energy.