Acceleration Of Charged Particles Research Articles

Huizhou accelerator complex facility and its future development

This paper provides an overview of the frontier research fields and significant questions in nuclear physics regarding particle accelerators, and the status and future development trends for big-science facilities of particle accelerators are reviewed. Two Chinese government-approved “12th Five-Year” major science infrastructure facilities, the “High Intensity heavy-ion Accelerator Facility (HIAF)” and “China Initiative Accelerator Driven System (CiADS)”, are being constructed in Huizhou, Guangdong Province. Based on these two big-science projects (HIAF and CiADS), we proposed to establish a large-scale charged particle accelerator complex facility named the “Bright Electron and Ion research Facility (BEIF).” This facility will be dedicated to the research and development of nuclear physics and its interdisciplinary frontier fields. The research frontier fields of nuclear physics at the BEIF will include nuclear structure and astrophysics, nucleon structure, quark matter phase structure, and interdisciplinary fields between several significant frontiers of fundamental and nuclear physics, such as highly charged atomic physics and heavy ion-driven high energy density physics. BEIF will be a large-scale scientific complex facility comprising several superconducting ion LINAC accelerators, synchrotrons, storage rings, reactors, and various large experimental detectors and setups. BEIF will be built in three construction phases and will become one of the premier global large-scale particle accelerator complex facilities dedicated to the research of nuclear physics and technology.

Non-resonant acceleration of charged particles driven by the associated effects of the radiation reaction

In the present analysis, we study effects of the radiation reaction (RR) on the dynamics of charged particles submitted to the action of localized longitudinal high-frequency carriers travelling at the speed of light. As the wave's crests and troughs keep overtaking particles, dissipative RR forces tend to drag particles alongside the wave in an effort to reduce the relative wave–particle speed. Particles of course never reach the phase velocity of the wave, but are instead driven to an ever-growing velocity, towards the speed of light, while in the wave localization region. We developed a modified average Hamiltonian formalism capable of describing the intricacies of the corresponding dynamics. The modified formalism agrees with simulations and is of particular usefulness in the study of optimum values for the localization length and maximum wave amplitude.

Acceleration of charged particles in rotating magnetized star

Charged particles at the crust of compact stars may be ejected and accelerated by the induced electric field generated due to the rotation of the magnetized star. For neutron or hybrid stars, the negatively charged particles are usually electrons, and the positively charged particles are mainly protons and iron. Whereas, the existence of strange stars also includes the possibility of ejection of strangelets from the star surface. The energy of such strangelets emitted from all known pulsars is in the range of 109–1010 GeV. Therefore, such massive strangelets can be one of the candidates for the sources of the highest-energy cosmic rays that have still eluded us. Our model proposes a possible origin of these ultra high energy cosmic rays.

Solar Cosmic Ray Acceleration at the Front of a Fast Shock in the Lower Solar Corona

Based on the theory of diffusive shock acceleration of charged particles, we have numerically studied the spectra of protons produced by a fast shock with a speed of 5000 km s–1 in the lower solar corona with known solar plasma parameters. We show that protons with energies $$ \gtrsim $$ 105 MeV can be produced at a distance up to 3 $${{R}_{ \odot }}$$ ( $${{R}_{ \odot }}$$ is the solar radius) within 274 s.

Two Phases of Solar Flares and a Stochastic Mechanism for Acceleration of Electrons and Protons

The hypothesis of two phases of charged particle acceleration in solar flares is well known, with subrelativistic electrons accelerated in the first phase and relativistic electrons and protons in the second. Both phases are distinguished in the solar proton events and their parent flares of December 26, 2001 (M7.1), November 2, 2003 (X8.3), and August 9, 2011 (X6.9), while in the interplanetary space only electrons were observed from the first phase and electrons and protons from the second. The temporal profiles of the electrons and protons from the second phase are similar; hence, it is concluded that the relativistic electrons and protons observed in the interplanetary space are predominantly accelerated in flares, rather than in the shock front of a coronal mass ejection. Most likely a stochastic acceleration mechanism is realized in flares where protons and electrons gain energy in many elementary events over the entire duration of the flare which lasts much longer than an elementary event. To ensure consistency of a stochastic acceleration process with the existence of two phases in solar flares it is necessary to consider gyrosynchronous radiative electron losses in the second phase which can be neglected in the first phase. The energy of the accelerated protons in the first phase is small for their detection in processes taking place on the sun, but in the second phase it may be sufficient to produce gamma lines, both nuclear and from pion decay.

Boron neutron capture therapy: Current status and future perspectives.

The development of new accelerators has given a new impetus to the development of new drugs and treatment technologies using boron neutron capture therapy (BNCT). We analyzed the current status and future directions of BNCT for cancer treatment, as well as the main issues related to its introduction. This review highlights the principles of BNCT and the key milestones in its development: new boron delivery drugs and different types of charged particle accelerators are described; several important aspects of BNCT implementation are discussed. BCNT could be used alone or in combination with chemotherapy and radiotherapy, and it is evaluated in light of the outlined issues. For the speedy implementation of BCNT in medical practice, it is necessary to develop more selective boron delivery agents and to generate an epithermal neutron beam with definite characteristics. Pharmacological companies and research laboratories should have access to accelerators for large‐scale screening of new, more specific boron delivery agents.

NON-EXCITING WAKEFIELD STRUCTURED BUNCHES IN A ONE-DIMENSIONAL PLASMA MODEL

A model of one-dimensional (1D) cold plasma with an external train of rigidly structured bunches with diverse charges has been introduced. In this model, a solution is presented that cancels the wakefield after the train is found. The density of such bunches can be much greater than the density of the plasma, and a high amplitude electrical field arising inside the train can be used for charged-particle acceleration. In addition, analytical and numerical simulations have been performed.

An 18.3 MJ charging and discharging pulsed power supply system for the Space Plasma Environment Research Facility (SPERF). I. The overall design.

The Space Plasma Environment Research Facility (SPERF) is a new ground-based experimental device for fundamental research studies on space plasma currently under construction at Harbin Institute of Technology in China. Scientific objectives of the SPERF include studying the asymmetric reconnection dynamics relevant to the interaction between the interplanetary and magnetospheric plasmas, reproducing the inner magnetosphere to simulate the processes of trapping, acceleration, and transport of energetic charged particles restrained in a dipole magnetic field configuration, and revealing the physical mechanism of the dipolarization front in the magnetotail. The device comprises a vacuum chamber, 11 coils consisting of 18 groups of sub-coils that are independently programmablely energized, and the plasma source system to provide the magnetic field and the plasma required by the physical experiments. Thus, each of these 18 groups of sub-coils requires a separate pulsed power supply; furthermore, the 18 pulsed power supplies constitute the pulsed power supply system of the SPERF of which the total storage energy is up to 18.3 MJ, and the technical challenges have to be overcome. The power supply energizing a dipole field coil (labeled OJC coil) wired by the copper wire to provide a dipole magnetic field is the most energetic power supply (labeled OJC power supply) with a 2.42 MJ, 16.8 mF capacitor bank charged to 20 kV. The OJC power supply delivers a current with a peak of 18 kA for a rise time of ∼26.69 ms, and the duration of the current is not less than 95% of the peak over 10 ms to the OJC coil. Meanwhile, the most challenging power supply is the power supply labeled poloidal field power supply with a 5.04 mF capacitor bank charged to 20 kV, which provides the excitation current for the load coil set with the current not less than 360 kA at the typical time of 0.11 ms to produce the sufficient growth of the magnetic field that the experiments need. In this paper, the overall design of the pulsed power supply system, the design concept of the modularization, and the principle selection basis of the key components are presented. The technical details of each power supply will be demonstrated in the future.

Physics-based deep neural networks for beam dynamics in charged particle accelerators

This paper presents a novel approach for constructing neural networks which model charged particle beam dynamics. In our approach, the Taylor maps arising in the representation of dynamics are mapped onto the weights of a polynomial neural network. The resulting network approximates the dynamical system with perfect accuracy prior to training and provides a possibility to tune the network weights on additional experimental data. We propose a symplectic regularization approach for such polynomial neural networks that always restricts the trained model to Hamiltonian systems and significantly improves the training procedure. The proposed networks can be used for beam dynamics simulations or for fine-tuning of beam optics models with experimental data. The structure of the network allows for the modeling of large accelerators with a large number of magnets. We demonstrate our approach on the examples of the existing PETRA III and the planned PETRA IV storage rings at DESY.

Erratum: “The Acceleration of Charged Particles at a Spherical Shock Moving through an Irregular Magnetic Field” (2017, ApJ, 848, 123)

Erratum: “The Acceleration of Charged Particles at a Spherical Shock Moving through an Irregular Magnetic Field” (2017, ApJ, 848, 123)

Towards ultra-high gradient particle acceleration in carbon nanotubes

Charged particle acceleration using solid-state nanostructures is attracting new attention in recent years as a method of achieving ultra-high acceleration gradients in the order of TV/m. The use of carbon nanotubes (CNTs) has the potential to overcome limitations of using natural crystals, e.g. channelling aperture and thermo-mechanical robustness. In this work, we present preliminary particle-in-cell simulation results of laser and beam interaction with a single CNT, modelled as 20 parallel plates of Carbon ions and electrons. This is the equivalent to a 10-layers tube in 3D. We further discuss simulation of anisotropic particles to model 2D quasi-free electrons in CNT walls. Further research ideas are outlined along with the presentation of a possible proof-of-principle experiment.

Cross sections of alpha-particle induced reactions on natNi: Production of 67Cu

The 67Cu is considered as one of the most perspective radio isotopes in targeted radio-immunotherapy medical applications. 67Cu is a β–-emitter with a mean β– energy, which allows treating tumors in size up to about 4 mm. Its decay is followed by emission of low energy gamma-rays suitable for gamma-camera imaging. The about three days half-life (T1/2 = 61.83 h) is optimal for human applications. However, one of the main drawback factors for its application is still the limited supply of 67Cu. There are several possibilities to produce 67Cu. High flux reactors, charged particle accelerators and high-energy bremsstrahlung radiations can be used to produce 67Cu. In this work we have studied one of the promising charged particle production routes based on the 64Ni(α,p)67Cu nuclear reaction. Cross sections for formation of 67,64,61,60Cu, 62,63Zn and 56,57Ni were studied up to 50 MeV alpha-particle energy on nickel targets with natural isotopic composition.

Diagnostics of the Efficiency of a Gas Stripping Target of a Tandem Accelerator with Vacuum Insulation

Abstract— Diagnostics have been developed for measuring the efficiency of stripping a beam of negative ions in a gas stripping target of a tandem charged particle accelerator. The coefficient of ion-electron emission during the bombardment of copper by protons with an energy of 1 MeV was measured. A bending magnet with a horizontal nozzle was installed, which made it possible to place a Faraday cup and receive a stream of neutrals formed on it as a result of incomplete stripping of negative ions in the stripping target. Diagnostics of the efficiency of the gas stripping target were put into operation on the basis of measuring the current of electrons emitted from the surface of a Faraday cup during its bombardment by a directed stream of neutrals and the proton current by a non-contact current sensor.

Measuring the Emittance of a Charged-Particle Beam in a Small Linear Accelerator

A “non-contact” method for measuring the emittance of a corpuscular flow extracted from the Penning ion source of a small linear charged-particle accelerator has been developed and tested. The emittance is calculated by minimizing the difference between the theoretically calculated and experimentally measured beam sizes in the ion-optical system of the accelerator. The dimensions are measured during photographic recording of a luminous trace of a corpuscular flow in the ion-optical system. The results of applying the non-contact method for measuring the emittance of a particle beam flow are presented.

Nonstationary Quasiperpendicular Shock and Ion Reflection at Mars

AbstractCollisionless shocks in space plasma are regions of heating and acceleration of charged particles and dissipation of kinetic energy. These accelerated particles are the source of electromagnetic emissions from supernova remnants and other astrophysical structures. At high Mach numbers, shocks can be inherently nonstationary and exhibit modulated energy transfer and recurring plasma compression areas in the form of reformation. We use data from the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft to study reformation of the Martian bow shock, which has a relatively high curvature compared to that at Earth, and the upstream solar wind is often mass loaded with a population of pickup ions. We show evidence of ion reflection effects in reformation of a supercritical quasiperpendicular shock.

Enhancement of ion energy and flux by the influence of magnetic reconnection in foam targets

Laser-driven ion acceleration attracts large attention due to variety of applications. In order to enhance accelerated proton energy and flux, we investigate the influence of laser-driven relativistic magnetic reconnection on the ion acceleration processes. In this relativistic regime, the longitudinal electric field becomes significantly enhanced and plays an important role in charged particle acceleration. To realize conditions for the magnetic reconnection, two spatially separated relativistic laser beams were used. The results obtained show a shift of high energy proton propagation direction compare to that corresponding to the target normal sheath acceleration scenario as well as enhancement in proton flux.

DIELECTRIC RF RESONATORS WITH OPEN BOUNDARIES FOR STUDYING RADIATION EFFECT ON ELECTRODYNAMIC CHARACTERISTICS OF SOLID DIELECTRICS

The use of dielectric materials in the charged particles accelerators requires investigation of changes in the electrodynamic properties of these materials under the influence of ionizing radiation. First of all it is necessary to study the effect of radiation on the complex dielectric permittivity (ꜫ and tgδ) of these materials. The actual task is to measure very small relative changes in the dielectric constant, for example, ∆ꜫ/ꜫ~10-4. Such accuracy can be provided by resonator methods. In the present work results of theoretical and experimental research of microwave dielectric resonators with open boundaries are given. It is shown, that they can be used to measure dielectrics during irradiation by gamma radiation or charged particles beam. The analysis of factors that affect the accuracy of measurements is carried out.

Juno Observations of Heavy Ion Energization During Transient Dipolarizations in Jupiter Magnetotail.

Transient magnetic reconnection and associated fast plasma flows led by dipolarization fronts play a crucial role in energetic particle acceleration in planetary magnetospheres. Despite large statistical observations on this phenomenon in the Earth's magnetotail, many important characteristics (e.g., mass or charge dependence of acceleration efficiency and acceleration scaling with the spatial scale of the system) of transient reconnection cannot be fully investigated with the limited parameter range of the Earth's magnetotail. The much larger Jovian magnetodisk, filled by a mixture of various heavy ions and protons, provides a unique opportunity for such investigations. In this study, we use recent Juno observations in Jupiter's magnetosphere to examine the properties of reconnection associated dipolarization fronts and charged particle acceleration. High-energy fluxes of sulfur, oxygen, and hydrogen ions show clear mass-dependent acceleration with energy ~ m 1/3. We compare Juno observations with similar observations in the Earth's magnetotail and discuss possible mechanism for the observed ion acceleration.

Machine learning for orders of magnitude speedup in multiobjective optimization of particle accelerator systems

High-fidelity physics simulations are powerful tools in the design and optimization of charged particle accelerators. However, the computational burden of these simulations often limits their use in practice for design optimization and experiment planning. It also precludes their use as online models tied directly to accelerator operation. We introduce an approach based on machine learning to create nonlinear, fast-executing surrogate models that are informed by a sparse sampling of the physics simulation. The models are 10^6 to 10^7 times more efficient to execute.We also demonstrate that these models can be reliably used with multi-objective optimization to obtain orders-of-magnitude speedup in initial design studies and experiment planning. For example, we required 132 times fewer simulation evaluations to obtain an equivalent solution for our main test case, and initial studies suggest that between 330 to 550 times fewer simulation evaluations are needed when using an iterative retraining process. Our approach enables new ways for high-fidelity particle accelerator simulations to be used, at comparatively little computational cost.

Basic types and technological implementation of charged particle accelerators

The modern particle accelerators have developed greatly over the last 100 years. This article provides an overview of all main types of particle accelerators. Simple charts are given to exhibit conceptual and technological evolutions of major particle accelerators. It also briefly introduces the basic types, fundamental principles, technological approaches, and typical technical features of various types of particle accelerators.