High-current Accelerator Research Articles

Electric Vehicle Boost Charging System Using Supercharging Capacitor

Over the past two and a half decades, electric vehicles (EVs) have attained a magnificent market, and the day by day it is increasing throughout the world. It is also one of the hopeful remedies for the greenhouse gases. But the main difficulty is the charging of the battaries. To charge an electric vehicle takes a long time period, and it is also not safe because they use lithium-ion batteries to run them. Lithium-ion batteries require 5 to 6 hours for their charging, and the battery banks are bulky as well as heavier and are not fireproof. The lifespan of lithium-ion batteries is also too short; they last for less than 3 years. By using the supercharging capacitor instead of lithium-ion batteries in electric vehicles, the above-mentioned restrictions can be overcome easily. Super-capacitor modules can provide the high current and high acceleration while the vehicle is starting, as well as they are very hopeful to increase the life of batteries. The design of this project includes a charger and battery technology that is fast in charging, fireproof, and long-lasting. This charging system has high-amps-supported electronic circuits and electronic components used for charging of 2.7 V and 1000 F (500 F x 2 Nos.) capacitors.

Electron Screening in Laboratory Nuclear Reactions

A thorough understanding of nuclear reaction rates at low energies is essential for improving our understanding of energy generation in stars and primordial and stellar nucleosynthesis. At low energies, fusion reactions between charged particles are strongly suppressed by the presence of the Coulomb barrier, which classically inhibits the penetration of one nucleus into another. The barrier penetration causes the cross section to have a steep energy dependence at low energies, making cross section measurements very challenging. Furthermore, little is known about the impact of surrounding electrons in stellar plasmas that are currently beyond the reach of experiments. As a result, measuring the bare cross sections as accurately as possible is essential. Reaction rate measurements at very low energies have been made possible in recent years by the development of high-current low-energy accelerators as well as enhanced target and detection methods. Nevertheless, the presence of atomic electrons, which alter the Coulomb barrier by screening the nuclear charge and increase the cross section at low energies compared to the case of bare nuclei, complicates these observations. A review of the experimental and corresponding theoretical work on laboratory electron screening performed so far will be presented.

Ultrafast laser triggered electron emission from ultrananocrystalline diamond pyramid tip cathode

Nitrogen-incorporated ultrananocrystalline diamond [(N)UNCD] pyramid tip cathode has been considered as a next-generation high peak current electron source for dielectric laser accelerators as well as other high peak current particle accelerator applications. In this work, we study non-linear photoemission from an (N)UNCD pyramid tip cathode using an ultrafast laser with the pulse length of 150 fs with the central wavelength of 800 nm in the peak intensity range of 109–1010W/cm2. We demonstrated that as the incident laser intensity increases, the current emitted from the nano-tip first increases as a power function with an exponent of about 5 and then starts to roll over to an exponent of 3. This roll over is attributed to the Coulomb interaction between electrons emitted from the tip also known as the space charge. We also measured the photoemission electron energy spectra that show electrons with energies as high as ∼10 eV. Based on the shape of the electron energy spectra, we conclude that the high-energy electrons are thermally emitted electrons due to ultrafast laser heating at the tip of the (N)UNCD pyramid tip cathode.

Simulation of Secondary X-Ray of Sterilization Setup Based on High-Current Pulse Electron Accelerator SINUS-320

Simulation of Secondary X-Ray of Sterilization Setup Based on High-Current Pulse Electron Accelerator SINUS-320

Fabrication and rejuvenation of high quantum efficiency caesium telluride photocathodes for high brightness and high average current photoinjectors

With their high quantum efficiency (QE) and excellent photoemissive properties, cesium telluride (Cs-Te) photocathodes are the current workhorse in the high average current electron accelerators around the globe. Their ability to generate high brightness and high charge electron beams has opened the doorway to numerous applications, including fundamental particle physics research, radiation therapy, high-energy physics experiments, and high repetition rate free-electron lasers (FELs). Their long-term performance is critical. In this work, we analyze the systematic production and rejuvenation of photocathodes via thermal evaporation and deposition techniques (both sequential and co-deposition), showing excellent values of QE exceeding 20% using deep ultraviolet illumination (λ=262–266 nm). To extend the photocathode lifetime, the rejuvenation process is performed via multilayer thin-film co-deposition, demonstrating the feasibility of reliably recovering the initial QE even after air exposure. We evaluated their final performance in both high gradient dc and rf gun setups and obtained consistent results of QE and lifetimes. The technique can be used at the gun level, which significantly extends the sustained accelerator operation without major interventions. These approaches significantly enhance the robustness and performance of Cs-Te photoinjectors and represent a significant advancement for reliable high average current electron accelerators and FELs. Published by the American Physical Society 2024

Research on the heat resistance and electrical properties of fluorinated polyimide/nano-Al2O3/nano-Si3N4 composite materials

Polyimide (PI) refers to a polymer containing an imide ring characteristic structure on the main chain. It has excellent thermal stability, insulation properties and other characteristics. The Tesla transformer is the core component of the primary pulse source of the high-current electron beam accelerator. It is also an essential component of the energy storage pulse power supply. Therefore, it has broad application prospects in the fields of national defense and civil industry. If the insulation performance of the turn-to-turn coils of the Tesla transformer does not meet the standards, it will break down during high-voltage corona discharge, causing transformer failure. Therefore, it is crucial to improve the insulation performance of Tesla transformer inter-turn wrapping materials. The incorporation of fluorine-containing groups has proven to be a transformative strategy that significantly enhances the physical, chemical, optical, and electrical properties of PI films. In addition, numerous studies have demonstrated that introducing inorganic fillers into the polyimide matrix can substantially enhance the insulating properties of polyimide films. This paper specifically concentrates on elevating the insulating and thermal attributes of polyimide. Initially, a range of polyimide films was synthesized for performance assessment by employing various fluorinated dianhydride and diamine components, utilizing them as substrates. Then, we used nano-silicon nitride (nano-Si3N4) and nano-alumina (nano-Al2O3) as doping phases to prepare PI composite films, which reduced the dielectric constant and increased the breakdown strength.

Profile of Inner Magnetically Insulated Transmission Lines to Minimize Energy Loss Under MA/Cm Lineal Current Density for High-Current Pulsed-Power Accelerators

Profile of Inner Magnetically Insulated Transmission Lines to Minimize Energy Loss Under MA/Cm Lineal Current Density for High-Current Pulsed-Power Accelerators

Conceptual design of the high-power electron beam irradiator using niobium-tin superconducting cavity

In recent years, there has been an increasing demand for high-intensity beams in the field of electron beam irradiation. This includes mass production of nuclear medicine examinations using 99Mo and high-efficiency production through material modification via material irradiation. Although superconducting cavities can achieve high-current beam acceleration, a compact accelerator is desirable for general-purpose irradiation beams. In this paper, we designed a practical 10 MeV, 50 mA high-current beam irradiator using a new Nb3Sn superconducting cavity.

Beam Dynamics Studies for the Target Beamlines of the High Brilliance Neutron Source

The High Brilliance Neutron Source (HBS) belongs to the class of High Current Accelerator based Neutron Sources (Hi-CANS). The driver Linac for the HBS must be able to reliably accelerate a 100 mA proton beam to an energy of 70 MeV [2, 1, 3]. The beam is sent pulse-by-pulse to three different targets via a multiplexer in the High Energy Beam Transfer (HEBT) section. Each individual proton pulse behind the multiplexer has a specific time structure in order to optimally serve the different instruments grouped around one target station. The main development steps of the HEBT are the development of a three-field septum magnet, which is an essential part of the multiplexer magnet system, the beam dynamics integration of the multiplexer magnet system into the beamline, and the ion-optical layout of the individual target beamlines.

Experimental Study of the Compressibility of a Helium Plasma at a Pressure up to 20 TPa

A nonideal helium plasma has been compressed to a density of ρ ≈ 14 g/cm3at a pressure ofP≈20TPa (200Mbar) in a spherical two-cascade device. The design of the device has been presented and the thermodynamic parameters of the helium plasma reached in it have been estimated. Data on the dynamics of the external and internal cascades in the device used to choose the calculation method have been obtained in a preliminary experiment with a hemispherical prototype. The experiment has been performed on the X-ray complex at the Russian Federal Nuclear Center All-Russian Research Institute of Experimental Physics, which includes BIM 234.3000 betatrons with a boundary energy of 60 MeV used in the multipulse bremsstrahlung generation regime with a multichannel optoelectronic system of recording X-ray images. A high-current linear accelerator LIU-R-T and an image detector assembly consisting of photochromic ADC screens have been used in addition to betatrons to detect the compressed shell cavity.

Electric field in the RF cavity with large beam duct for high current beam acceleration

A acceleration scheme using a bunch of single-cell cavities as the first-stage acceleration of ion beams. The single-cell cavity has been shown the possibility of accelerating high-current beams of 1 A or more. As an elemental test before we started a cavity fabrication, we compared simulations of the electric field distribution with experiments utilizing the existing cavity.

Experimental Study of the Compressibility of a Helium Plasma at a Pressure up to 20 TPa

A nonideal helium plasma has been compressed to a density of ρ ≈ 14 g/cm3 at a pressure of \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$P \\approx 20{\\kern 1pt} $$\\end{document} TPa (200 Mbar) in a spherical two-cascade device. The design of the device has been presented and the thermodynamic parameters of the helium plasma reached in it have been estimated. Data on the dynamics of the external and internal cascades in the device used to choose the calculation method have been obtained in a preliminary experiment with a hemispherical prototype. The experiment has been performed on the X-ray complex at the Russian Federal Nuclear Center All-Russian Research Institute of Experimental Physics, which includes BIM 234.3000 betatrons with a boundary energy of 60 MeV used in the multipulse bremsstrahlung generation regime with a multichannel optoelectronic system of recording X-ray images. A high-current linear accelerator LIU-R-T and an image detector assembly consisting of photochromic ADC screens have been used in addition to betatrons to detect the compressed shell cavity.

OPTICAL DIAGNOSTICS SYSTEM AT THE INURA ACCELERATOR

A system has been created for extracting and transporting light radiation from the irradiation chamber and the protective box of the INURA accelerator. Light outside the protective box is recorded using compact spectrometers, photomultipliers, photodetectors in the range from 300 nm to 2.1 µm. At present, the accelerator operates in the ion acceleration mode; the number of problems to be solved should increase when switching to the electron acceleration mode. The system was tested in the registration of light radiation from the interelectrode gap of the diode assembly. Lines of a hydrogen atom and an oxygen atom associated with the decomposition of absorbed water vapor and the discharge over the dielectric surface at the anode of the high-current accelerator diode have been registered.

Innovative research and development activities on high energy and high current isochronous proton accelerator

The MW class proton accelerators are expected to play important roles in many fields, attracting institutions to continue researching and tackling key problems. The continuous wave (CW) isochronous accelerator obtains a high-power beam with higher energy efficiency, which is very attractive to many applications. Scholars generally believe that the energy limitation of the isochronous cyclotron is ∼1 GeV. To get higher beam power by the isochronous machine, enhancing the beam focusing become the most important issue.Adjusting the radial gradient of the average magnetic field makes the field distribution match the isochronism. When we adjust the radial gradient of the peak field, the first-order gradient is equivalent to the quadrupole field, the second-order, the hexapole field, and so on. Just like the synchrotron, there are quadrupoles, hexapole magnets, and so on, along the orbits to get higher energy, as all we know.If we adjust the radial gradient for the peak field of an FFA's FDF lattice and cooperate with the angular width (azimuth flutter) and spiral angle (edge focusing) of the traditional cyclotron pole, we can manipulate the working path in the tune diagram very flexibly. During enhancing the axial focusing, both the beam intensity and the energy of the isochronous accelerator are significantly increased. Here a 2 GeV CW FFA with 3 mA of average beam intensity design is presented. It is essentially an isochronous cyclotron although we use 10 FDF lattices. The key difficulty is that the magnetic field and each order of gradient should be accurately adjusted in a large radius range.As a high-power proton accelerator with high energy efficiency, we adopt high-temperature superconducting (HTS) technology for the magnets. 15 RF cavities with a Q value of 90000 provide energy gain per turn of ∼15 MeV to ensure the CW beam intensity reaches 3 mA. A 1:4 scale, 15-ton HTS magnet, and a 1:4 scale, 177 MHz cavity have been completed. The results of such R&D will also be presented in this paper.

Thermal moderator-reflector design of the 24 Hz target station for the High Brilliance Neutron Source

The High Brilliance Neutron Source (HBS) project develops a high current accelerator driven neutron source (HiCANS), aiming to substitute existing neutron research reactors, that reach the end of life. This study focuses on the thermal neutron moderator design for a low frequency, long pulse target station of HBS. We investigate the neutronic characteristics of the D2O+H2O mixture moderator material using the Monte Carlo particle transport code PHITS. Our findings show that, compared to D2O with lower neutron absorption, confinement of H2O is the dominant factor in achieving a high neutron flux within the moderator and thus a high neutron brightness. We find that surrounding the central thermal water moderator with a D2O+H2O mixture can achieve a better balance between confinement and absorption. However, because of multiple angles of reflecting neutron, this design will also increase the divergence of the neutron beam.

The High Brilliance Neutron Source Target Stations

High Current Accelerator driven Neutron Sources (HiCANS) are a cost-efficient alternative for future large scale neutron facilities. They excel in transforming neutrons released by the primary nuclear reaction into a spectral range usable for applications. In particular, the cost of a target station represents only a minor fraction of the overall construction cost due to the lower energy of the primary neutrons, which requires less shielding. They can be designed to provide optimized pulse and spectral properties for applications in neutron scattering, analytics and imaging experiments. For the High Brilliance neutron Source (HBS) project at Forschungszentrum Jülich, we have developed a modular design that meets the radiation protection requirements while providing sufficient space in its core to adapt the target-moderator-reflector assembly to the different applications. In the following, we present the basic target station design which will be used at HBS for three different realizations with their own instrument suite. All relevant components have been designed, built and tested at the JULIC Neutron Platform which has produced neutrons since December 12th 2022. The simulated performance of a target station shows that the brightnesses of the moderators are in the range of modern research reactors and sub-MW power spallation sources.

Model of a 5-MA Linear-Transformer-Driver Accelerator: Transmission-Line-Circuit Method and Three-Dimensional Field-Circuit Coupling Method

A 5-MA-LTD-based, high current accelerator is modeled using transmission line code. And the machine performances are presented for driving short-circuit loads, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Z$ </tex-math></inline-formula> -pinch loads, and bremsstrahlung electron beam diodes. With simulation analysis, it is expected that the short-circuit load current can reach 4.7 MA in 100 ns with ±80 kV LTD charge voltage, and the peak of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Z$ </tex-math></inline-formula> -pinch load current when the machine is conducted with a 0.45 mg wire-array can be high as 4.2 MA, the peak kinetic energy is 49 kJ, and the energy coupling efficiency is estimated as 38%. The physical model of the reflex triode load which is typical electron beam diode is presented in detail. By incorporating the physics-based reflex triode model into a 3-D transient electromagnetic model, the field-circuit coupling simulation can be performed and the results are compared with the circuit model. The results from these two methods are in good agreement. The peak load current when the machine is configured with a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 0.15~\Omega $ </tex-math></inline-formula> reflex triode load is ~2.8 MA. The energy coupling efficiency to the reflex triode load is 35.8%.

Thermomechanical responses of the drift tube to beam loss at the China spallation neutron source.

The China Spallation Neutron Source drift tube linac (DTL) is a high current intensity linear accelerator operated in pulsed mode. Beam loss is the most important cause of DTL performance degradation. Therefore, control of beam loss is very crucial to the linac's commission and routine operation. The beam loss in beam pulse width (∼several hundreds of microseconds) can be regarded as an instantaneous process, which may cause the local temperature of the drift tubes (DTs) to exceed the melting point or the thermal stress to exceed the material yield strength, resulting in permanent damage to the DTs. RF heating and beam loss are two major heat sources of the DTs during operation. First, temperature rise due to RF power dissipation is evaluated in this paper. Then, the thermomechanical response due to beam loss at different energies is investigated. It is found that the 3-MeV beam loss has the greatest stopping power and causes the largest temperature rise to the DTs. The maximum beam current loss for different working conditions is analyzed by both analytical method and ANSYS simulations, and the details will also be discussed in this paper.

Direct comparison of analytically derived “Fedosov” solution with experimental measurements and numerical simulations of relativistic thin annular electron beam generation and propagation in magnetically insulated coaxial diode of SINUS-6 high-current electron-beam accelerator

The analytically derived solution for a thin annular electron-beam generation in a magnetically insulated coaxial diode (MICD), also known as “Fedosov solution,” is validated by direct experimental measurements of current–voltage (I–V) characteristics of MICD driven by the high-current electron-beam accelerator SINUS-6 and numerical particle-in-cell (PIC) simulations of a thin annular electron-beam generation and propagation in computer model of MICD of corresponding geometry and initial/boundary conditions. The experimental measurements of I–V characteristics of MICD are performed by monitoring and analyzing a voltage applied to MICD and an electron-beam current generated by an explosive-emission cathode of MICD. Numerical simulations of MICD operation are performed using ICEPIC code. The comparisons of analytically derived “Fedosov” solution with experimentally measured I–V characteristics of MICD as well as with results of ICEPIC simulations of a three-dimensional computer model of MICD operation are analyzed, and a conclusion is made that all three measures are pretty much consistent with each other. The appliance of the analysis is purposed now in using SINUS-6 accelerator for designing, prototyping, and studying different variants of O-type slow-wave high-power microwave/millimeter-wavelength vacuum electronic devices.

The design of a high-voltage, long-pulse width, flat-top compensation pulse generator based on metal oxide varistors.

In recent years, the pulse forming technology based on metal oxide varistors (MOVs) has been verified to be an effective way to generate high-voltage quasi-square pulses. Due to the limited varistor voltage of a single MOV brick, multiple MOV bricks connected in series are required to stabilize a pulse with high amplitude (larger than hundreds of kV), which leads to the rise of the series inductance of the MOV branch and the flat-top droop in the output waveform. This paper provides two solutions to reduce the influence of the MOV branch inductance on output waveforms. One is that a coaxial evolute structure of the MOV bricks connected in series is designed, which can not only improve the insulation capacity but also reduce the branch inductance. Another is that a flat-top compensation scheme named "PFN-MOV" (Pulse Forming Network) is proposed, which adds an LC filtering branch to shape the signal into a flat-top rising wave with ripple and then offsets the flat-top droop caused by the inductance of the MOV branch. Based on the above ideas, a high-voltage, long-pulse width, flat-top compensation pulse generator is designed and tested, and a quasi-square pulse with voltage amplitude of more than 500kV, pulse width greater than 800ns, rise time of less than 50ns, and flat top of about 600ns is obtained experimentally. This MOV based generator has the advantage of simple design, compact construction, and better flat top, which is promising to be used as a compact long-pulse driver in many fields, such as high-current accelerator, industrial dedusting, medical sterilization, and cancer treatment.