Acceleration Of Charged Particles Research Articles

X-Ray Polarimetry of Magnetic Turbulence and Cosmic Rays in Supernova Remnants

Young supernova remnants (SNRs) are effective accelerators of charged particles. Particle acceleration is accompanied by the amplification of turbulent magnetic fields. The structure of SNR synchrotron intensity and polarization maps is sensitive to features of this field, especially in the X-ray energy band. Numerical modeling of synchrotron SNR maps is performed for different models of magnetic turbulence. The capabilities of a new-generation IXPE polarimeter designed to study magnetic turbulence in the vicinity of SNRs are discussed.

About Azimuthal Acceleration of the Electrons by Azimuthal Surface Waves in a Dielectric-Lined Circular Waveguide With Two Thin Annular Rotating Electron Beams

Considering two annular rotating electron beams in a dielectric-lined waveguide, the frequency spectrum of the azimuthal waves and their field profile distribution are investigated. The charged particle acceleration due to the tangential component of the electric field is simulated. The simulation is carried out for important factors, such as the electron energy gain (acceleration gradient) and the deflection angle in two different vacuum regions (the core and clad of the dielectric waveguide). The graphs of the mentioned parameters versus the traveled distance by the electron are presented, and they are compared with each other. It is found that in some cases, the tangential acceleration of the charged particle in the clad of the cylindrical waveguide can be more effective.

Particle acceleration mechanism due to interaction between one-dimensional fast plasma flow and perpendicular magnetic field

We have numerically investigated the behavior of one-dimensional fast plasma flow in a perpendicular magnetic field for understanding the particle acceleration mechanisms of collisionless shocks in the non-relativistic region. Electromagnetic hybrid particle-in-cell simulation was performed for simulating pulsed-power-driven fast plasma flow. Numerical results showed that accelerated particles are generated in the plasma flow after passing through the perpendicular magnetic field. The gradient of the compressed magnetic field due to the propagation of the plasma flow affects the acceleration of charged particles. The maximum energy of accelerated particles depends on the initial peak strength of the perpendicular magnetic field.

Ultrashort Optical Pulses and Their Generation in Resonant Media (Scientific Summary)

Our recent studies of methods for obtaining ultrashort light pulses and analysis of the impact of ultrashort optical pulses on classical and quantum micro-objects with the identification of the determining role of the degree of unipolarity of pulses (maximum for strictly unipolar pulses) in the efficiency of direct laser acceleration of charged particles and excitation of atoms and molecules have been reviewed. Special attention has been paid to the coherent mode locking regime in lasers, which is implemented when the laser pulse duration is less than the relaxation time of the working transition in media with resonance amplification and absorption (laser analog of the phenomenon of self-induced transparency). Experimental data on coherent mode locking in a titanium-sapphire laser with a cell with rubidium vapor at self-induced transparency in rubidium have been presented. The interaction of ultrashort pulses in resonant media has also been analyzed.

Design of a 352.2 MHz, 100 kW CW power klystron

ABSTRACTA 352.2 MHz klystron with an output power of 100 kW CW is under development at CSIR-CEERI for charged particle accelerator application. The paper presents various design results achieved through simulation of the electron gun, radio frequency (RF) interaction structure and collector for the device. Based on the design results, a beam stick tube has been developed and hot tested for which the test results are given. A study for the design of RF interaction structure of this klystron has been carried out to get the optimized design parameters using 1-D code AJDISK and MAGIC (2D/3D). The intermediate RF cavities have been developed and characterized for their designed frequencies and the results of cold RF measurements are given.

A System for Beam-Position Diagnostics in the Channel of the Multiturn Microtron–Recuperator at the Novosibirsk Free-Electron Laser

A system for diagnostics of the electron-beam position in the channel of the microtron–recuperator (MR) of the Novosibirsk free-electron laser is described. The position of the beam is measured using electrostatic BPM stations that are installed in different parts of the vacuum chamber on the path of the beam along the accelerator channel. The features of the operation of the multiturn MR resulted in the necessity to develop an algorithm for measuring the beam position that differs from the algorithms that are used on other charged-particle accelerators. This system can be used to measure the positions separately of both accelerated and decelerated beams that are simultaneously present in some segments of the MR.

Relativistic HPIC-LBM and its application in large temporal-spatial turbulent magnetic reconnection. Part II. Role of turbulence in the flux rope interaction

Quantitatively analyzing the role of turbulence in the magnetic fluctuation-induced self-generating-organization region and the plasma turbulence-induced self-feeding-sustaining region, which is closely related to the evolution of null points and the magnetic helical structure, represents the key issues in understanding the magnetic energy release-conversion, plasma heating, and charged particles energization and acceleration in three-dimensional large temporal-spatial scale turbulent magnetic reconnection (3D LTSTMR). The first part of this two-paper series developed and validated the continuous kinetic-dynamic-hydro fully coupled temporal-spatial scale relativistic hybrid particle-in-cell and lattice Boltzmann (RHPIC-LBM) model and code for investigating the fine structure evolution of the 2.5D solar atmosphere LTSTMR activities. Based on the model and code developed in Part I, in this paper, we investigate the turbulence of the magnetic helical structure, current density vector fields, self-generating-organization magnetic potential vector fields, self-feeding-sustaining plasma motion, and the ion and electron acceleration of 3D LTSTMR with 100,000 CPU cores on the Tianhe-2 from National Supercomputer Center in Guang Zhou (NSCC-GZ). According to the simulation evidence, we discovered and confirmed the following results: (i) Slipping magnetic reconnection (MR) exists in the adjacent magnetic field lines (MFLs) during the compress-stretch-slip process on the quasi-separatrix layers (QSLs and MFLs drastically change and form a linkage span) and the adjacent MFLs’ break-rejoin MR exists on the separatrix surfaces (SLs). Both are consistent to observations; (ii) The slipping MR (defined as 1st type MR) and the MFLs’ break-rejoin MR (defined as 2nd type MR) are closely linked with the oblique and resistive tearing instabilities, respectively. In the 3D model, the 1st type MR forms O-type null points, while the 2nd type MR forms X-type null points. The magnetic energy conversion is dominated by turbulence-induced oblique instabilities in the 3D model instead of the resistive tearing instabilities in the 2D/2.5D model, which is consistent with the 3D observations; (iii) Magnetic energy conversion occurs in the interaction of the plasmoid-to-flux rope, plasmoid-to-plasmoid, and flux rope-to-flux rope. The turbulent acceleration is an independent acceleration mechanism in LTSTMR, induced by the interaction of waves-to-waves and waves-to-particles, which is different from the original hybrid acceleration mechanism (composed of parallel electric fields, betatron, shock and Fermi) ; (iv) Particles can be energized and accelerated at a longer time scale (−30 s) and can be accelerated to relativistic energies after being pre-accelerated by a Fermi-Betatron-shock wave acceleration process. These results are in agreement with the observations.

Studying the Energy Spectra of Background Gamma Radiation Increases

Several detectors have been integrated into a single system for monitoring the electromagnetic component of secondary cosmic rays (SCRs) at the Cosmic Ray Laboratory of the Polar Geophysical Institute (Apatity). The system includes a differential gamma-ray spectrum detector based on a NaI(Tl) crystal. One gamma-ray spectrum is collected in 30 min. The energy range is 0.2–8 MeV. It should be noted that like other detectors, the spectrometer was precalibrated using known lines. Background gamma radiation increases during precipitation. More than 1500 such events have been detected since the detector became operational. A number of long-term measurements have been made thus far, which make it possible to study in detail the energy parameters of increase events. The main aim of the study is to compare the characteristics between the spectra in clear weather and under different types of precipitation. Particular attention is given to radiation analysis of samples collected during the rain. The results show there is no pollution of water with radionuclides. It is concluded that the observed effect is due to purely atmospheric effects. A preliminary interpretation of the phenomenon is the creation of a model for the acceleration of charged particles of SCRs in the electromagnetic fields of nonthunderstorm rain clouds. The results from calculations are presented, and their consistency with the experimental data is shown.

<italic>In situ</italic>measurements of the solar eruption

This work introduces a deep space mission of the great significance on the aspects of sciences and applications. Success of this mission will allow us to observe and detect the magnetic activities and the reconnection region occurring on a star at an unprecedentedly short distance by combining the remote sensing and the in situ approaches. First of all, we propose to access the core of the energy release region for the solar storm, namely the reconnecting current sheet, detecting and measuring fine structures and details of several important processes that include the magnetic diffusion, energy conversion, charged particle accelerations, and so on. Second, we shall perform the in situ measurement of components and distributions of the plasma and magnetic field inside the coronal mass ejection (CME, also known as the solar storm), helping us investigate and study the mechanism of CME and the original source of the plasma inside CME; detect the radio bursts caused by the energetic particles produced by reconnection in the current sheet and the CME-driven shock, collect these particles, and perform the in situ measurements of the CME-driven shock. Third, we shall measure the coronal magnetic field directly at the helio-distance ranging from 5$R_{\\rm~odot}$ to 10$R_{\\rm~odot}$, which is a key for looking into the energetics and dynamics of the solar eruption, and will further help as well resolve the problem of the corona heating, a century-long puzzle for solar physicists. Fourth, applying the method of imagining and spectroscopy, we are able to observe and study the dynamic process taking place in the high layer of the solar atmosphere with fairly high resolution. Usually, the highest resolution of observing the corona on the ground is around 1.5 arc-second ($1.5^{\\prime\\prime}$), and this value is lower in most of the cases, the in situ measurements at very short distance would enhance the resolution by a factor between 5 and 30. This will provide us an opportunity to study, look into, and understand the closest and the most important star to us at an unprecedentedly high level, and eventually help resolve the long-term problem and the puzzle like triggering of the solar eruption, magnetic reconnection, and corona heating. This is also a unique chance for us to look closely at or to perform the in situ measurement of the magnetic reconnection process taking place in the atmosphere of a star.

Acceleration of charged particles to extremely large energies by a sub-Dreicer electric field

Acceleration of a fraction of initially low-energy electrons in a cold, collisional plasma to energies orders of magnitude larger than thermal is shown to be possible with a sub-Dreicer electric field. Because such an electric field does not satisfy the runaway condition, any acceleration will be statistical. Random scattering collisions are probabilistic such that there is 63% chance that a particle collides after traveling one mean free path and a 37% chance of not colliding. If one considers only the electrons that do not collide on traversing a mean free path and also considers that the collisional mean free path scales quadratically with particle kinetic energy, one realizes that there will be a small fraction of electrons that never collide and are accelerated to increasingly high energy. Because the mean free path scales quadratically with kinetic energy, after each successfully traveled mean free path, continued acceleration becomes more likely. This model is applied to an MHD-driven plasma jet experiment at Caltech and it is shown that electrons are accelerated by an electric field associated with a fast magnetic reconnection event occurring as the jet breaks apart. This statistical acceleration model indicates that a fraction ∼1.3 × 10−7 of electrons with initial energy distributed according to a Maxwellian with T = 2 eV will be accelerated to 6 keV in the Caltech experiment and then collide to produce the observed X-ray signal. It is shown that the statistical acceleration model provides a credible explanation for the production of solar energetic electrons.

Проблемы обеспечения радиационной безопасности персонала при эксплуатации терапевтических ускорителей протонов на примере центра протонной терапии в Димитровграде

Currently, charged particle accelerators are used not only as a tool for basic research, but they are also becoming increasingly common in industry and medicine. In Russia in the coming years it is planned to create 3 centers of proton and ion therapy. At the same time, the instrumental, methodological, metrological and regulatory support of radiation monitoring does not currently correspond to the energy range of the generated radiation. The paper analyzes the compliance of existing regulatory and advisory documents with the goals of ensuring radiation safety during proton therapy.

Optimal matching control of a low energy charged particle beam in particle accelerators

Particle accelerators are devices used for research in scientific problems such as high energy and nuclear physics. In a particle accelerator, the shape of particle beam envelope is changed dynamically along the forward direction. Thus, this reference direction can be considered as an auxiliary &#x201C time &#x201D beam axis. In this paper, the optimal beam matching control problem for a low energy transport system in a charged particle accelerator is considered. The beam matching procedure is formulated as a finite &#x201C time &#x201D dynamic optimization problem, in which the Kapchinsky-Vladimirsky &#x0028 K-V &#x0029 coupled envelope equations model beam dynamics. The aim is to drive any arbitrary initial beam state to a prescribed target state, as well as to track reference trajectory as closely as possible, through the control of the lens focusing strengths in the beam matching channel. We first apply the control parameterization method to optimize lens focusing strengths, and then combine this with the time-scaling transformation technique to further optimize the drift and lens length in the beam matching channel. The exact gradients of the cost function with respect to the decision parameters are computed explicitly through the state sensitivity-based analysis method. Finally, numerical simulations are illustrated to verify the effectiveness of the proposed approach.

Dynamics of relativistic laser-produced plasmas

We present a brief overview of physical processes in a plasma under the action of relativistically strong electromagnetic radiation generated by high-power lasers. Attention is focused on nonlinear waves in a laser plasma for the creation of compact electron accelerators. Then, we address the acceleration of plasma bunches by the radiation pressure of light, which is the most efficient regime of ion acceleration. Coherent hard electromagnetic radiation in the relativistic plasma is generated in the form of high harmonics and/or electromagnetic pulses, which are compressed and intensified after reflection from relativistic mirrors created by nonlinear plasma waves. These processes are of interest in view of the development of novel methods for acceleration of charged particles and the development of sources of bright and hard electromagnetic radiation.

Energy Release from Magnetospheres Deformed by Gravitational Waves

Abstract In this work, we consider the possibility of energy release in pulsar magnetospheres deformed by gravitational waves (GWs) from nearby sources. The strong electromagnetic fields in the magnetospheres may release non-negligible energy despite the weakness of the GW. When the background spacetime is perturbed due to the passage of a GW, the original force-free state of the inner magnetosphere will be slightly violated. The plasma-filled magnetosphere tends to evolve into new force-free states as the spacetime varies with time. During this process, a small portion of the electromagnetic energy stored in the magnetosphere will be released to the acceleration of charged particles along the magnetic field lines. When the pulsar is close enough to the GW source (e.g., pc to the GW sources observed recently), the resulting energy loss rate is comparable with the radio luminosity of the pulsar. It is also noticed that, under very stringent conditions (for magnetars with much shorter distance to the sources), the released energy can reach the typical energy observed from fast radio bursts.

The Study of Ar I and Ne I Spectral Line Shapes in the Cathode Sheath Region of an Abnormal Glow Discharge

The cathode sheath (CS) region is the most important part of abnormal glow discharge (GD), where various processes relevant for the operation and application occur. The most important parameter of the CS is the distribution of electric field strength E which is of crucial importance for charged particles acceleration, their trajectories, kinetic energies, and collisions with other particles and cathode sputtering. All these processes are relevant for the operation of GD as well as for numerous applications in the field of spectroscopic analysis, plasma etching, thin film deposition, and depth profiling of cathode material. Thus, the importance of non-perturbing technique for E distribution measurement in the CS region was recognized long time ago. Within this article, a simple technique based on standard optical emission spectroscopy (OES) and typical laboratory equipment has been used for E mapping in the CS region of an abnormal glow discharge.

O.I. Akhiezer Institute of Theoretical Physics

Professor A.I. Akhiezer is an outstanding Soviet theoretical physicist who made an outstanding contribution to the development of science. He is one of the most active in the field of theoretical physics of Soviet scientists. He has done about a hundred papers on various problems of nuclear physics, quantum electrodynamics, and the theory of charged particle accelerators. A number of difficult and ingenious studies, which gave fundamental results, made a significant contribution to the development of these problems and made his name known and authoritative among scientists of the Soviet Union and abroad. Professor A.I. Akhiezer is one of the best Soviet theoretical physicists working in the field of atomic nucleus physics and quantum electrodynamics. He is the author of first-class works on the scattering of γ-quanta by nuclei, on the diffraction scattering of nuclear particles. He established the possibility of a new phenomenon — diffraction splitting of deuterons by nuclei. AI Akhiezer is the author of the pioneering work on the scattering of neutrons in crystals, which have become particularly important in connection with the question of the moderation of neutrons. Of great importance was his first work to determine the critical dimensions of the reactor, taking into account the slowing down of neutrons. Of particular note are the works of Professor A.I. Akhiezer and his school on the theory of linear accelerators of charged particles and the theory of plasma.

Electric Area of an Extremely Short Pulse and Moment of Force

The electric area of a radiation pulse, which is defined as a time integral of the electric field strength, is interpreted as a mechanical moment of the Lorentz force acting on a unit electric charge upon its interaction with the radiation pulse. Correspondence between the classical mechanics law of conservation of momentum and the change in the moment of force upon the interaction of a quantum object with an intense extremely short radiation pulse is demonstrated. The high efficiency of acceleration of charged particles with quasi-unipolar radiation pulses is confirmed.

Radiation reaction of a charged particle with the external rectangular force

We considered the equation of motion of an accelerating point charged particle which produced the radiation reaction force that described by the Abraham-Lorentz equation. Then we considered another equation of motion from a different approach so-called Landau-Lifshitz equation which came from a limit in the case of a finite spherical shell charged particle. This latter equation shows that an acceleration of charged particle depends on an external force and its derivative. We showed the solution of the acceleration from the external rectangular force of these equations. So we solved the velocity and position of the charged particle. As a result, we compared the solutions from the Abraham-Lorentz and Landau-Lifshitz equations of motion.

Piezoelectric Accelerator

Here we propose the conception of small-size piezoelectric accelerator of charged particles that operates due to the piezoelectric effect at varying mechanical force applied to piezoelectrics in vacuum. The accelerating voltage and the energy of accelerated particles are estimated. In the proof-of-principle experiment we demonstrate the effect of the emission of X-ray radiation at the mechanical compression of piezoelectric ceramics in vacuum. The compression leads to the appearance of charges and potentials on the surfaces of the piezoelectrics and also to the arising of the electric field in vacuum. Electrons are accelerated in the electric field, strike the matter and produce the X-ray radiation. In the experiment, we have observed emission of the characteristic and bremsstrahlung X-ray radiation of energy up to 60 keV due to the compression of piezoelectric ceramics in vacuum. This means that electrons are accelerated in the piezoelectric accelerator up to the energy at least of 60 keV. The agreement of calculated and experimental data confirms the conception. Advantages of the piezoelectric accelerator and possibilities of its development and applications are discussed.

Electron Acceleration and Subsecond Time Delays of Hard X-Rays of Solar Flares According to Lomonosov Satellite Data

On the basis of satellite observations obtained with the help of X-ray and gamma-ray detector units (BDRG/Lomonosov in Russian), using digital filtering methods, the analysis of time delays between the second pulsations of time profiles of hard X-ray radiation of different frequency bands from the solar flare that occurred on July 21, 2016 has been made. It is shown that the count rate in energy channels of 10–20, 20–35, and 35–60 keV detected by BDRG/Lomonosov are correlated with an accuracy up to 0.1 s. The result agrees well with the observations of the Gamma-ray Burst Monitor on board the Fermi satellite and supposes an effective acceleration of charged particles over the entire length of the flare magnetic arc.