Design Of Electron Gun Research Articles

Design and study of the shape parameters for the electrode plates of the electron gun in the four-dimensional transmission electron microscope.

The accelerating electrode of a four-dimensional transmission electron microscope electron gun is modeled. The general expression of the electric-field distribution is derived for any point on the axis in a cylindrical coordinate system, and equations for the shape parameters of the electrode plate are obtained. The accuracy of the field expression is determined for different electrode plate parameters, and the shape parameters of the electron gun electrode are further investigated. This work can provide a theoretical basis for the initial design of a transmission electron microscope electron gun and the retrofit design of a four-dimensional electron gun.

Design and performance of a low-emittance electron gun for electron beam probe

An Electron Beam Probe (EBP) is preferable to provide a non-interceptive measurement of the transverse distribution of a dense bunched ion beam. During EBP operation, it was observed that the electron beam spot subjects to expansion when scanned across the ion beam due to the strong space charge field of the ion bunch, leading to significant degradation of spatial resolution. To mitigate this effect, a small electron beam spot is beneficial as demonstrated in previous research. This paper presents design details of a low-emittance, small-spot, and long-work-distance electron gun. Geometry optimization of the gun and focus lens is conducted using a multiobjective genetic algorithm (MOGA) interfaced with space charge simulation codes to maintain normalized thermal emittance within an acceptable increase and achieve a small spot at a long work distance. The emittance is measured using a slit-screen technique, resulting in a norm. rms emittance of 0.046(+-0.005) um*rad under low beam current conditions (50 nA). In high-resolution mode, a beam spot size of 0.6 mm (rms) is achieved at a work distance of 1.2 m with the combination of Einzel lens and solenoid. The gun has been successfully operated as part of EBP experiments for accurate and high-resolution measurement of ion beam width, demonstrating excellent agreement with wire scanner measurements with relative deviation not exceeding 1%.

FENNECS: A novel particle-in-cell code for simulating the formation of magnetized non-neutral plasmas trapped by electrodes of complex geometries

This paper presents the new 2D electrostatic particle-in-cell code FENNECS developed to study the formation of magnetized non-neutral plasmas in geometries with azimuthal symmetry. This code has been developed in the domain of gyrotron electron gun design, but solves general equations and can be applied in other domains of plasma physics. FENNECS is capable of simulating electron-neutral collisions using a Monte Carlo approach and considers both elastic and inelastic (ionization) processes. It is also capable of solving the Poisson equation on domains with arbitrary geometries with either Dirichlet or natural boundary conditions. The Poisson solver is based on a meshless Finite Element Method, called web-splines, based on b-splines of any order, and used for the first time in the domain of plasma physics. In addition, the effect of fast ions colliding with the electrodes and causing ion induced electron emission at the electrode surfaces has been implemented in the code. In this paper, the governing equations solved by FENNECS and the numerical methods used to solve them are presented. A number of verification cases are then reported. Finally, the parallelization scheme used in FENNECS and its parallel scalability are presented.

Electrostatic Design of a Tunable Tetrode Electron Gun for Electron Beam Additive Manufacturing Device

Electrostatic Design of a Tunable Tetrode Electron Gun for Electron Beam Additive Manufacturing Device

EARLI: design of a laser wakefield accelerator for AWAKE

Following the successful Run 1 experiment, the Advanced Proton Driven Plasma Wakefield Acceleration Experiment (AWAKE) Run2 experiment requires the design and implementation of a compact electron source. The “high-quality Electron Accelerator driven by a Reliable Laser wakefield for Industrial uses” (EARLI) project aims to design a stand-alone high-quality electron injector based on a laser wakefield accelerator (LWFA) as an alternative proposal to AWAKE’s baseline design of an X-band electron gun. This project is currently in the design phase, including simulations and experimental tests. Exhaustive beam physics studies for conventional accelerators are applied to LWFA physics.

Photo-emission electron gun and electron optical simulation for ultrafast scanning electron microscope

Ultrafast scanning electron microscope (USEM) integrates pump-probe technique with microscopic imaging, enabling the visualizing of photon-induced surface charge dynamics with high spatial and temporal resolution. This capability is crucial for high-resolution detection of semiconductor surface states and optoelectronic devices. This work discusses the parametric design of a thermionic emission electron gun that has been modified into a photoemission electron gun, based on a home-built ultrafast scanning electron microscope. Given that the dose of the photoemitting electron beam is usually much lower than that of thermionic emission, the transition to photoemission requires the removal of the self-bias voltage function of the original electron microscope power supply to ensure the normal operation of the Wehnelt electrode. We quantitatively analyze the dependence of bias voltage, cathode, Wehnelt electrode, and anode on the position, size and divergence angle of crossover, which helps to improve the parameter adjustment of the modified electron gun. The analysis results indicate that if the distance between the Wehnelt electrode and the anode is adjusted from 8 to 23 mm, the distance between the filament and wehnelt can be changes from 0.65 to 0.45 mm to cooperate with the bias adjustment, so that the normal use of high-resolution thermionic emission mode, low voltage mode and photoemission mode can be realized. Subsequently, the effect of the mirror’s position on the electron optical path is analyzed. It is found that when the anode is raised 1.4 mm above the mirror, the influence on the electron optical path can be ignored. Additionally, the zero-of-time and temporal broadening of the photo-electron pulse are further simulated. The results indicate that with the increase of bias voltage, the time zero of photoemission will be delayed and the temporal broadening will become larger. This study lays a foundation for the future development of ultrafast electron microscope and the design of photoemission electron sources.

Design of a simplified electron gun without BFE for linear beam tubes

Design of a simplified electron gun without BFE for linear beam tubes

Design and experimental evaluation of electron gun and periodic permanent magnet focussing structure of a Ku-band space-TWT

Design and experimental evaluation of electron gun and periodic permanent magnet focussing structure of a Ku-band space-TWT

Design and development of a sheet-beam electron gun with large current for a THz traveling-wave tube

Design and development of a sheet-beam electron gun with large current for a THz traveling-wave tube

A Novel Electron Gun Design Approach With an Externally Assembled Anode

A Novel Electron Gun Design Approach With an Externally Assembled Anode

Design and testing of a high perveance sheet beam electron gun

This paper presents the design, prototype engineering, and initial testing of a relatively low-voltage, high aspect ratio electron gun for versatile pulsed power applications. The sheet beam, diode electron gun is designed for (23–25) kV voltage and 6 µA/V1.5, as is required for x-band klystron, as a part of a compact Klylac delivering electron beam energy in the MeV range. The gun prototype was engineered, built, and tested using a Scandinova M1-0.5 modulator. Beam loss on the anode aperture is evaluated from transient waveforms and equivalent circuit modeling.

Design, fabrication, and tuning of a THz-driven electron gun

We present the design, fabrication, and cold testing of a THz-driven field emission electron gun. The gun is designed as a two-cell standing-wave structure with a copper tip inserted halfway into the first cell that serves as the field emission source. It is powered by a 110 GHz gyrotron and is expected to produce 51 fC, 360 keV electron bunches with an input power of 500 kW. Several gun structures were fabricated using a high precision diamond turned mandrel and copper electroforming. The frequencies of the cavity resonances were mechanically tuned using azimuthal compression.

Effect of the Gap Size between the Cathode and the Wehnelt Cylinder Bore on the Emittance of the Thermionic Electron Gun

This paper includes simulating an electron gun design to investigate the effect of the distance between the cathode and the Wehnelt cylinder bore on the quality of the ion beam emittance and to obtain the best distance of that geometrical factor. A study of a group of designs was conducted to find this distance. The SIMION8.0 program has been used to calculate the trajectories of the electrons with initial kinetic energy of (0.1 eV) and electron current of (1×10-12 A). The investigation also includes comparisons between the equipotential line trajectories for each design as well as the field distribution and the electron trajectories. The best emittance distance was concluded to be (3 mm).

Relativistic versus Nonrelativistic Approaches to a Low Perveance High Quality Matched Beam for a High Efficiency Ka-Band Klystron

Advanced technical solution for the design of a low perveance electron gun with a high quality beam dedicated to high power Ka-band klystrons is presented in this paper. The proposed electron gun can be used to feed linear accelerating structures at 36 GHz with an estimated input power of 20 MW, thus achieving an effective accelerating electric field in the (100–150) MV/m range. Additionally, in the framework of the Compact Light XLS project, a short Ka-band accelerating structure providing an integrated voltage of at least 15 MV, has been proposed for bunch-phase linearization. For the klystron, a very small beam dimension is needed and the presented electron gun responds to this requirement. An estimate of the rotational velocity at beam edge indicates that the diamagnetic field due to rotational currents are small compared to the longitudinal volume. A detailed analysis of how this has been achieved, including compression of the beam, rotation in the magnetic field, and analysis of the subsequently generated diamagnetic field has been discussed.

Optical simulation analysis and study of UTEM electron gun

In this paper, the electric field intensity of the electrode structure of the thermally emitted electron gun of UTEM is simulated, and the relation between the electric field intensity distribution and the electrode plate is analyzed. Using the electronic optics software, the optical system of the electron gun is simulated, the performance parameters of the electron gun are obtained, and the advantages and disadvantages of the whole optical system are analyzed. The research results of this paper can provide a reference for the design and simulation of similar electron gun.

A High-Current-Density Electron Beam for Millimeter-Wave Amplifiers

We present experimental characterization of a 20-kV, 130-mA thermionic electron gun, which is a component of a ${W}$ -band traveling-wave tube (TWT) power amplifier. The electron beam is strongly focused by a 6.6-kG permanent magnet solenoid, producing a peak current density up to 800 A/cm2. The cathode temperature, focus electrode voltage, and modulating anode voltage are varied to characterize the emitted cathode current and beam transport through the beam tunnel of the TWT RF circuit. We observe the variation of the cathode current from 107 to 155 mA and peak beam transmission of 95% measured at the collector. Experimental results are compared to 2-D simulations with the electron gun and collector design code MICHELLE.

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..

A co-axial electron gun to generate millimeter-wave RF using the two-stream instability.

A novel source for broadband millimeter-wave RF is being designed at Los Alamos National Laboratory utilizing the two-stream instability. This RF source offers the potential for consistent output power over a large bandwidth on a single device. The source is designed to use two co-axial electron beams coupled into solenoidal magnetic fields. This is accomplished using two cathodes independently modulated nested in each other. The electron beam energy from the innermost cathode will fall in the range between 15 and 20 keV with the beam energy from the outer cathode being 75%-95% of the inner beam energy. In order to efficiently match the beam from the outer cathode into the solenoidal magnetic field, shields are used around the cathodes to shape the electric field in the gun region to extend the electrostatic focal length of the beams for better coupling into the magnetic field. We present the design of electron guns and expected performance using Trak simulations.

Thermionic electron gun design and prototyping

Boğaziçi Üniversitesi KAHVE Laboratuvarı’nda prototip termiyonik electron tabancası, endüstriyel elektron demeti uygulamalarında deneyim kazanmak amacıyla tasarlanmış ve üretilmiştir. Elektron tabancası tungsten filament, Wehnelt bardağı, Faraday bardağı ve solenoid bileşenlerinden oluşmaktadır. Elektron tabancası benzetimleri IBSimu isimli program kullanılarak gerçekleştirilmiştir. Üretimi gerçekleştirilen elektron tabancası, 20 kV potansiyel ve 3 mA’e kadar demet akımında çalışmaktadır. Bu çalışma, termiyonik elektron tabancasının üretimi sırasında karşılaşılan sorunları ve deneysel sonuçları raporlamaktadır.

Design of an Electron Gun for an 8 MW Peak, 30kW Average Power S-Band Klystron

High Power S-band pulsed klystrons with peak power greater than 6 MW are widely used as RF sources in particle accelerators. This paper presents an electron gun (pierce type) design for such a klystron with an output power of 8 MW peak and 30 kW average with its intended applications in accelerators for food processing. The targeted device is currently under design at CSIR-CEERI and will be developed later on. The results of electron gun simulation through computational codes like Trak, CST particle studio, and Opera are compared to find an optimum design for the electron gun to be fabricated for the klystron.