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This paper reports the simulation of an electron gun. The effects of some
parameters on the beam quality were studied and optimal choices were
identified. It gives numerical beam qualities in common electrostatic triode
gun, and the dependences on design parameters such as electrode geometries and
bias voltages to these electrodes are shown. An ele...
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The High Energy Photon Source (HEPS) is the first high-energy diffraction-limited storage ring (DLSR) light source to be built in China, with a natural emittance of a few tens of pm rad and a circumference of 1360.4 m. After 10 years' evolution, the accelerator physics design of the HEPS has been basically determined, with the ring consisting of 48...
Citations
... Beam trajectories under electromagnetic fields are obtained from particle tracking solver (TRK). Static electromagnetic fields can be defined as the components along the beamline, where the charged particles are generated from static source area and/or volume [32,33]. The calculation is simply deduced from equation of motions, given by Lorentz force. ...
An alternative technique to verify terahertz (THz) Smith–Purcell radiation (SPR) was proposed by using different grating periods. A compact DC electron gun, serving as a THz source, was modified to generate continuous 35 keV electron beam that passes by a metal-coated silicon grating in order to induce SPR. A design on beam optics to generate high-brightness beam was carried out by using Computer Simulation Technology (CST) Studio Suite® software package. The optimization of beam parameters was obtained and experimentally performed. Results show that the root-mean-square (rms) beam size (diameter) is about 1 mm when supplying beam current of 200 µA, and rms beam emittance is about 3π mm mrad. The CST simulation software was, furthermore, employed to observe radiation spectra when using different grating structures. A liquid–helium cooled silicon bolometer together with a low-pass filter was used to detect radiation power. The results reveal that incoherent THz signal with power of 1.5 µW cm⁻² is observed when the continuous-beam current is about 200 µA. The dependence of THz frequency and power on the grating period, that is associated to the SPR, was also investigated in this work.
The electron gun, as a critical device for emitting high-speed electrons, determines the electron beam current and quality in electron beam additive manufacturing (EBAM). In this article, a tetrode electron gun with a control electrode is designed to improve the quality and controllability of the electron beam. The control electrode, optimized by parametric simulation, provides secondary confinement of the electron beam. This confinement aims to reduce the beam spot size and emittance while decoupling spot size from the current. Specifically, the maximum attainable current reaches 200 mA, while the beam waist radius contracts to a mere 1.09 mm. The normalized emittance, a crucial parameter, measures at 1.536
10
. Furthermore, stability analysis of the electron gun explores the influence of electrode potential on its performance. By co-regulating the bias voltage and the control voltage, the electron beam current can smoothly rise to 200 mA while maintaining the beam spot radius of 2 mm. This article indicates the tetrode electron gun’s potential for precise control, thereby improving the quality and precision of high melting point alloy additive manufacturing processes.
Low-perveance electron guns are highly desired in high-efficiency space TWTs mainly due to the low operating beam current. In a low-perveance electron gun, the distance between the cathode and beam-forming electrode (BFE) plays a critical role in achieving laminar electron beam flow with the required specifications. It is an extremely sensitive parameter that gets affected by minor variations in the dimensions occurring due to thermal expansion. Hence, thermal and structural simulations are carried out to back-calculate the distance at which the cathode must be placed from the BFE during fabrication under cold conditions. In this article, the authors have presented the development of two electron guns–one developed based on the ideal simulation results and for the other one, the practical brazing conditions were considered in the simulations. Both the guns were integrated with TWTs, and their performances were evaluated under the same operating voltages and magnetic focusing conditions. It has been observed that the electron gun fabricated based on practical simulation conditions performed well with a low helix interception current. In contrast, the other gun had poor performance with a high helix interception current. Hence, it experimentally validates the fact that simulation considering the practical brazing scenario has resulted in precise back-computation of the cathode-BFE distance and hence better beam transmission characteristics of the tube.
PurposeThe research focuses on the simulation of influence of cathode positions on beam current characteristics in the thermionic electron gun.Methods
The electric field distribution, bias voltage range and electron beam quality under different cathode positions were simulated by CST software.ResultsChanges in the cathode position can cause changes in the electric field distributions under the cathode emission surface change, thereby changing the size of the effective emitting area and affecting the relationship between the bias voltage and beam current.Conclusions
Only when the cathode is installed in the proper positions, the beam current and the bias voltage have an approximately linear proportional relationship. When the cathode is installed improperly, the electron beam emission is disordered, resulting in decreased electron beam quality.
Spectroscopy of transient anions and radicals by gated and accelerated time-of-flight experiment is a new spectrometer developed in UCLouvain. This instrument measures high-resolution photodissociation spectra of mass-selected ions by the combination of a time-of-flight spectrometer including a specific gating, bunching, and re-referencing unit with a nanosecond pulsed dye laser, a pulsed deflection, and an energy selector. The ionic species are generated in a supersonic jet expansion by means of an electric discharge or by the impact of electrons coming from an electron gun. The versatility of the molecular systems that can be addressed by this instrument is illustrated by the presentation of mass spectra of cations, anions, and ionic clusters formed from different gas mixtures and backing pressures. The high-resolution spectrum of the A~2Σ+(002)←X~2Π3/2(000) and A~2Σ+(002)←X~2Π1/2(000) rovibronic bands of N2O⁺ has been measured and analyzed to provide refined molecular parameters in the A~2Σ+(002) upper state. The A~2Σ+(002)←X~2Π3/2(000) band has been used to evaluate the quality of the experimental setup in terms of rotational temperature, time of measurement for certain signal to noise ratio, and the accuracy of the determination of the wavenumber scale.
Electron beam welding (EBW) has many advantages as a space environment welding technology. EBW is suitable for vacuum operations. It can ensure the quality of aerospace material welding joints, high energy efficiency, and maximum penetration depth regardless of the material type and surface conditions. It has been tested successfully many times in actual space environments. The effects of the space environment on the welding technology are analyzed from the aspects of microgravity, vacuum conditions, and temperature differences in this article. The research directions of space welding technology, the principles, and the structure and development course of vacuum electron beam welding are also expounded. The development of space electron beam gun technology in the United States and former USSR has been reviewed in detail, and the two typical structures and characteristics have been analyzed. This review can provide reference for the design of new space electron beam guns.
PurposeA structure, used as a complex source of X-rays and neutron source, is designed with the assistance of CST module tool.Methods
Particles of H- and electron, attracted from a plasma source, are designed to be separated by an energy selector. Soon after the separation, the trajectory and beam quality of H- are controlled by a special designation of potential barrier and potential well. And both particles are then accelerated by
three pairs of pierce similar pole to an energy of 150 keV to produce X-rays/neutron.ResultsWith proper optimization of structure and potential combination, a binocular structure with beam center distance of 15 mm, beam diameter smaller than 3.5 mm has been devised, which gives a feasible suggestion to produce two rays with one structure in the same time.
