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Orientational ordered soft matter possessing diverse microstructures has become a focal point of scientific research and technological exploration, thanks to its advancements in serving as an indispensable optical platform enabling propagation of light with multidimensional and manipulatable states. Herein, a facile way is developed to manipulate the in‐plane light beam transition dynamics by harnessing a time‐variable nematic liquid crystal (NLC) film through the electrical‐field‐induced topological defects. The results show that the dynamic change of optical branched flow is associated with the growth in the correlation length of optical potential and the reduction in the density of topological defects. The optical branching can continuously transform to deterministic and tunable beam steering at the low‐defect‐density regime through annihilation kinetics of defects. The explored soft matter system provides an excellent planar platform for the fundamental physics of light interacting with topological defects and may offer new perspectives for novel optics elements toward the applications of soft matter photonics. [ABSTRACT FROM AUTHOR]

Broadband vibration attenuation is a challenging task in engineering since it is difficult to achieve low-frequency and broadband vibration control simultaneously. To solve this problem, this paper designs a piezoelectric meta-beam with unidirectional electric circuits, exhibiting promising broadband attenuation capabilities. An analytical model in a closed form for achieving the solution of unidirectional vibration transmission of the designed meta-beam is developed based on the state-space transfer function method. The method can analyze the forward and backward vibration transmission of the piezoelectric meta-beam in a unified manner, providing reliable dynamics solutions of the beam. The analytical results indicate that the meta-beam effectively reduces the unidirectional vibration across a broad low-frequency range, which is also verified by the solutions obtained from finite element analyses. The designed meta-beam and the proposed analytical method facilitate a comprehensive investigation into the distinctive unidirectional transmission behavior and superb broadband vibration attenuation performance. [ABSTRACT FROM AUTHOR]

We investigate the dynamics of electrons initially counter-propagating to an ultra-fast ultra-intense near-infrared laser pulse using a model for radiation reaction based on the classical Landau–Lifshitz–Hartemann equation. The electrons, with initial energies of 1 GeV, interact with laser fields of up to 10 23 W/ cm 2 . The radiation reaction effects slow down the electrons and significantly alter their trajectories, leading to distinctive Thomson scattering spectra and radiation patterns. It is proposed to use such spectra, which include contributions from harmonic and Doppler-shifted radiation, as a tool to measure laser intensity at focus. We discuss the feasibility of this approach for state-of-the-art and near-future laser technologies. We propose using Thomson scattering to measure the impact of radiation reaction on electron dynamics, thereby providing experimental scenarios for validating our model. This work aims to contribute to the understanding of electron behavior in ultra-intense laser fields and the role of radiation reaction in such extreme conditions. The specific properties of Thomson scattering associated with radiation reaction, shown to be dominant at the intensities of interest here, are highlighted and proposed as a diagnostic tool, both for this phenomenon itself and for laser characterization in a non-intrusive way. [ABSTRACT FROM AUTHOR]

This paper is concerned with the well-posedness and long-time dynamics of a class of beam/plate equations with rotational inertia and nonlinear energy damping. The model is derived from nonlocal dissipative energy models for flight structures, as proposed by Balakrishnan-Taylor (Proceedings Damping 89, Flight Dynamics Lab and Air Force Wright Aeronautical Labs, WPAFB, 1989). Our main results address the existence of compact global attractors. The work complements the degenerate coefficient case left open by Sun and Yang (J. Math. Anal. Appl., Volume 512, Issue 2, 2022). [ABSTRACT FROM AUTHOR]

This document provides a summary of a special issue titled "Advances in Particle Acceleration: Novel Techniques, Instruments, and Applications." The special issue covers various topics related to particle acceleration. It discusses recent advancements in accelerator technologies, including new materials, fabrication techniques, and novel acceleration methods. The document specifically focuses on the advancements in radiotherapy methods for cancer treatment, as well as the development of radioisotope therapy. It also explores the pursuit of compact light sources and advancements in accelerator technologies for enhanced miniaturization, power capacity, reliability, sustainability, and cost-efficiency. The special issue includes several papers that cover topics such as beam dynamics software, RF cavity optimization, niobium cavity coating, efficient accelerator lattice design, plasma accelerator concept, and improvements to electrostatic dust accelerators. Overall, the special issue provides valuable insights into the latest advancements in particle acceleration. [Extracted from the article]

In the manual ball-and-beam task, participants have to control a ball that is rolling continuously on a long and hand-held beam. Since the task can be performed individually, in a solo action setting, as well as collaboratively, in a (dyadic) joint action setting, it allows us to investigate how joint performances arise from individual performances, which we investigate in a series of interrelated studies. Here we focused on individual skill acquisition on the ball-and-beam task in the solo action setting, with the goal to characterize the behavioral dynamics that arise from learning to couple (ball motion) perception and (beam motion) action. By moving a beam extremity up and down to manipulate the beam's inclination angle, the task's objective was to roll the ball as fast as and accurately as possible between two indicated targets on the beam. Based on research into reciprocal aiming tasks, we hypothesized that the emergent dynamics of the beam's inclination angle would be constrained by the size of the targets, such that large targets would evoke a continuous beam movement strategy, while small targets would lead to a discrete beam movement strategy. 16 participants individually practiced the task in two separate six-block sessions. Each block consisted of one trial per target-size condition (small, medium and large). Overall, the number of target hits increased over trials, due to a larger range of motion of the beam's inclination angle, a stronger correlation between the ball and beam motion and a smaller variability of the beam motion. Contrary to our expectations, target size did not appreciably affect the shape of the beam movement patterns. Instead, we found stable inter-individual differences in the movement strategies adopted that were uncorrelated with the number of target hits on a trial. We concluded that multiple movement strategies may lead to success on the task, while individual skill acquisition was characterized by the refinement of behavioral dynamics that emerged in an early stage of learning. We speculate that such differences in individual strategies on the task may affect the interpersonal coordination that arises in joint-action performances on the task. [ABSTRACT FROM AUTHOR]

Various approaches to mechanical modeling are available in practice to calculate the dynamic response of railway bridges under high-speed traffic, differing significantly in their complexity and accuracy. Very simple models often overestimate the vibrations occurring in reality but are much more computationally efficient and dependent on only a few input parameters than more complex and accurate models. Modeling the high-speed train as a multi-body system can represent the beneficial vehicle-bridge interaction, but it requires knowledge of numerous vehicle parameters, which manufacturers rarely disclose. In contrast, the track-bridge interaction can also be depicted by a simple coupling beam modeling of the structure, requiring only a few input parameters representing the dynamic stiffness and damping of the track. Several calculations on different single-span steel girder bridges demonstrate the influence of different model variants and input parameters on the acceleration results of the structure. Additionally, an approach for determining a dynamic distribution of the train axle loads affecting the bridge depending on the assumed vertical track stiffness is presented. [ABSTRACT FROM AUTHOR]

Solar type III radio bursts are crucial indicators of energetic electron activity in the solar corona and interplanetary space. Our assessment of 43 interplanetary type III bursts, recorded by the FIELDS instrument on board the Parker Solar Probe during Encounters 05 to 11, has led to significant and complex findings. We have analyzed time profile features across a frequency range of 19–0.5 MHz, revealing dependencies on frequency and providing insights into duration, burst speeds, bandwidths, and drift rates. This novel analysis has unveiled a spectral index of −0.63 ± 0.04 for rise, −0.69 ± 0.03 for decay time, and −0.68 ± 0.03 for the total duration. We have determined the average electron beam velocities for front, middle, and back as 0.15 c, 0.13 c, and 0.08 c, respectively. Our findings show that faster electron beams generate emissions with shorter duration. The average ratio of the front-to-back velocity is 1.87, and the ratio of front-to-middle velocity is 1.23. We have also discovered a strong relationship between burst duration with rise, peak, and decay times, particularly pronounced with decay time (correlation coefficient = 0.95). This indicates that the entire temporal profile, including rise, peak, and decay phases, collectively contributes to event duration and is not solely influenced by external factors like plasma conditions or electron beam dynamics but also by internal burst processes. These complex findings shed light on the physical mechanisms governing burst dynamics, revealing intricate interactions between electron beam characteristics and observed temporal and spectral traits of type III solar radio bursts. [ABSTRACT FROM AUTHOR]

The High Intensity Muon Beams (HIMB) project at the Paul Scherrer Institute (PSI) will deliver muon beams with unprecedented intensities of up to 10 10 muons / s for next-generation particle physics and material science experiments. This represents a hundredfold increase over the current state-of-the-art muon intensities, also provided by PSI. We performed beam dynamics optimisations and studies for the design of the HIMB beamlines MUH2 and MUH3 using Graphics Transport, Graphics Turtle, and G4beamline, the latter incorporating PSI's own measured π + cross-sections and variance reduction. We initially performed large-scale beamline optimisations using asynchronous Bayesian optimisation with DeepHyper. We are now developing an island-based evolutionary optimisation code glyfada based on the Paradiseo framework, where we implemented Message Passing Interface (MPI) islands with OpenMP parallelisation within each island. Furthermore, we implemented an island model that is also suitable for high-throughput computing (HTC) environments with asynchronous communication via a Redis database. The code interfaces with the codes COSY INFINITY and G4beamline. The code glyfada will provide heterogeneous island model optimisation using evolutionary optimisation and local search methods, as well as part-wise optimisation of the beamline with automatic advancement through stages. We will use the glyfada for a future large-scale optimisation of the HIMB beamlines. [ABSTRACT FROM AUTHOR]

The measurement of the spatial distribution of the nearly monocyclic terahertz (THz) fields by a raster scanning diaphragm is the widely used approach in THz pulse time-domain holography (PTDH) applied in imaging, optical component design, and wavefront sensing tasks. However, it is historically plagued by a compromise between the balance between the signal-to-noise ratio (SNR) and resolution. To address this challenge and keep both parameters at a high level, we proposed to replace the scanning aperture with the scanning module containing a conjugated diaphragm and lens. This solution allowed us for the first time to experimentally investigate the spatio-temporal dynamics of a Gauss–Bessel beam generated in a widespread low-energy THz system based on a femtosecond laser with a pulse energy of around a dozen nanojoules and a repetition rate of tens of megahertz. In particular, this allowed us to observe the temporal spectrum of the THz Gauss–Bessel field at the beam periphery with SNR ≈ 0.5 , which was not possible using a conventional raster scanning system. A careful numerical analysis of the proposed solution reveals a signal enhancement in the spectral domain of approximately 2.5 times compared to the THz PTDH raster scan detection employing only a diaphragm. Moreover, we have shown that the given solution ensures the temporal profiles remain unaffected by the quadratic phase aberration experienced in conventional raster field scanning with only a single aperture. [ABSTRACT FROM AUTHOR]

Effective control of skyrmion rotation is of significant importance in designing skyrmion-based nano-oscillators. In this work, we numerically study the optical vortex-driven skyrmion rotation in frustrated magnets using the Landau–Lifshitz–Gilbert simulations. The skyrmion rotation is induced by the orbital angular momentum (OAM) transfer from the optical vortex to the skyrmion, which is regardless of the sign of the OAM quantum number m due to the helicity degree of freedom of the frustrated skyrmion. This property highly broadens the parameter range of the optical vortex in controlling the skyrmion rotation. The direction of the rotation is determined by the sign of m, and the radius and angular velocity depend on the magnitude of m, light polarization, and intensity. Interestingly, the helicity oscillation induced by the linearly polarized beam is much slower than that driven by the circularly polarized beam with a same intensity, resulting in a faster rotation of the skyrmion. This phenomenon demonstrates the advantage of the linearly polarized beam in controlling the dynamics of the frustrated skyrmion, benefiting energy-saving and high-efficient device design. [ABSTRACT FROM AUTHOR]

In the present work, we extend the results of a previous investigation on the dynamics of electrons under the action of an inverse free-electron-laser scheme (Almansa et al. , Phys. Plasmas , vol. 26, 2019, 033105). While the former work examined electrons as single test particles subject to the combined action of a modulated wiggler plus a laser field, we now look at electrons as composing a particle beam, where collective space-charge effects are relevant and included in the analysis. Our previous work showed that effective acceleration is achieved when the initial velocities of the particles are close enough to the phase velocity of the beat-wave mode formed by the laser and the wiggler fields. Electrons are then initially accelerated by a ponderomotive uphill effect generated by the beat mode and, once reaching the phase velocity of the beat, undergo a final strong resonant acceleration step resembling a catapult effect. The present work shows that, under proper conditions, space-charge effects play a similar role as the initial (or injected) velocity of the beam. Even if acceleration is absent when space charge is neglected, it may be present and effective when charge effects are taken into account. We also discuss how far the space charge can grow without affecting the sustainability of the acceleration process. [ABSTRACT FROM AUTHOR]

In this paper, we have studied the influence of laser polarization on the dynamics of the ionization-injected electron beams, and subsequently, the properties of the emitted betatron radiation in laser wakefield accelerators (LWFAs). While ionizing by strong field laser radiation, the generated photo-electrons carry a residual transverse momentum in excess of the ionization potential via the above threshold ionization (ATI) process. This ATI momentum explicitly depends on the polarization state of the ionizing laser and eventually governs the dynamics of the electron beam trapped inside the wake potential. In order to systematically investigate the effect of the laser polarization, here, we have employed complete three-dimensional particle-in-cell simulations in the nonlinear bubble regime of the LWFAs. We focus, in particular, on the effects the laser polarization has on the ionization injection mechanism, and how these features affect the final beam properties, such as beam charge, energy, energy spread, and transverse emittance. We have also found that as the laser polarization gradually changes from linear to circular, the helicity of the electron trajectory, and hence the angular momentum carried by the beam, increases significantly. Studies have been further extended to reveal the effect of laser polarization on the radiation emitted by the accelerated electrons. The far-field radiation spectra have been calculated for the linear and circular polarization states of the laser. It has been shown that the spatial distributions and the polarization properties (Stokes parameters) of the emitted radiation in the above two cases are substantially different. Therefore, our study provides a facile and efficient alternative to regulate the properties of the accelerated electron beams and x-ray radiation in LWFAs, utilizing ionization injection mechanism. [ABSTRACT FROM AUTHOR]

Self-focusing emerges as a nonlinear optical phenomenon resulting from an intense laser field and plasma interaction. This study investigates the self-focusing behavior of Gaussian laser beams within magnetized plasma environments utilizing a novel approach, source-dependent expansion. By employing source-dependent expansion, we explore the intricate dynamics of laser beam propagation, considering the influence of plasma density and external magnetic fields. The interplay between the beam's Gaussian profile and the self-focusing mechanism through rigorous mathematical analysis and numerical simulations, particularly in the presence of plasma-induced nonlinearities, is elucidated here. Our findings reveal crucial insight into the evolution of laser beams under diverse parameters, including the ponderomotive force, relativistic factors, plasma frequency, polarization states, external magnetic field, wavelength, and laser intensity. This research not only contributes to advancing our fundamental understanding of laser–plasma interactions but also holds promise for optimizing laser-driven applications. [ABSTRACT FROM AUTHOR]

Aluminum and its alloys are widely used in various applications including e-mobility applications due to their lightweight nature, high corrosion resistance, good electrical conductivity, and excellent processability such as extrusion and forming. However, aluminum and its alloys are difficult to process with a laser beam due to their high thermal conductivity and reflectivity. In this article, the two most used laser processes, i.e., laser welding and laser powder bed fusion (LPBF) additive manufacturing, for processing of aluminum have been studied. There are many common laser-material interaction mechanisms and challenges between the two processes. Deep keyhole mode is a preferred method for welding due to improved productivity, while a heat conduction mode is preferred in LPBF aiming for zero-defect parts. In LPBF, the processing maps are highly desirable to be constructed, which shows the transition zone. Presented numerical modeling provides a more in-depth understanding of porosity formation, and different laser beam movement paths have been tested including circular oscillation paths. High accuracy processing maps can be constructed for LPBF that allows us to minimize tedious and time-consuming experiments. As a result, a modeling framework is a highly viable option for the cost-efficient optimization of process parameters. [ABSTRACT FROM AUTHOR]

Plasma wakefield acceleration revolutionized the field of particle accelerators by generating gigavolt-per-centimeter fields. To compete with conventional radio-frequency (RF) accelerators, plasma technology must demonstrate operation at high repetition rates, with a recent research showing feasibility at megahertz levels using an Argon source that recovered after about 60 ns. Here we report about a proof-of-principle experiment that demonstrates the recovery of a Hydrogen plasma at the sub-nanosecond timescale. The result is obtained with a pump-and-probe setup and has been characterized for a wide range of plasma densities. We observed that large plasma densities reestablish their initial state soon after the injection of the pump beam (< 0.7 ns). Conversely, at lower densities we observe the formation of a local dense plasma channel affecting the probe beam dynamics even at long delay times (> 13 ns). The results are supported with numerical simulations and represent a step forward for the next-generation of compact high-repetition rate accelerators. The authors report about a proof-of-principle experiment that demonstrates the recovery of a Hydrogen plasma accelerator at the sub-nanosecond timescale. The result is obtained with a pump-andprobe setup and represent a step forward for the next-generation of compact high-repetition rate plasma-based accelerators. [ABSTRACT FROM AUTHOR]

The design, simulation, and beam dynamics analysis of the integrated illumination system of the scanning electron microscope (SEM) have been reported. The dimensions and capacity of the SEM components, such as the electron gun, electron column, and lenses, were determined using the finite element method. The optimization of the illumination system was performed, and characteristics beam parameters were studied analytically. The gun consisted of a simple diode structure having; cathode, Wehnelt, and anode electrodes. A tungsten cathode of diameter 150 μm was used to emit the electrons thermionically. The electrons beam was generated at 2700 K with acceleration potential of 15 kV. Pair of electromagnetic lenses producing field strengths, 221 mT and 253 mT, respectively, focused the beam at 56.5 mm from cathode, with beam diameter of 9 μm in the post anode region. The calculated value of beam brightness was 2.97 × 106 A/(mm-rad)2. The final beam spot thus obtained was stable and perfectly symmetric along the two transverse directions. Gun assembly and lenses are thermally stable at the operational temperature. The illumination system geometry offers full-beam collimation control with reduced column length, making it suitable for electron diffraction studies, where focusing of the beam onto a sample is desired. [ABSTRACT FROM AUTHOR]

At an experiment on acceleration of a polarized proton beam up to an energy at , the possibility of crossing the transition energy at by a jump is considered. The scheme of crossing by a rapid change of transition energy, assumes the longitudinal movement in Barrier Bucket RF near the zero value of the slip-factor. The jump itself is carried out in the absence of an RF field. The paper presents the influence of the above features on the dynamics of a polarized beam. [ABSTRACT FROM AUTHOR]

Fourth-generation storage rings enabled by multi-bend achromat lattices are being inaugurated worldwide and many more are planned for the next decade. These sources deliver stable ultra-high brightness radiation with unmatched levels of transverse coherence by virtue of their highly advanced magnetic lattices. Optimization of these challenging and strongly nonlinear lattices with many degrees of freedom bounded by extensive sets of constraints and multiple often conflicting optimization goals is highly demanding and requires application of the most advanced numerical tools available to the community. While multi-objective genetic algorithms have been very successful in supporting these optimization efforts, the algorithms suffer from a fundamental limitation of their stochastic nature: an exceedingly vast number of candidate lattices, most of which eventually are rejected, has to be fully evaluated. This comes at immense computational cost and thus drives excessive runtime despite use of large supercomputing clusters. We therefore propose to employ deep learning techniques and iterative retraining of neural networks to massively accelerate such lattice evaluation, thereby allowing lattice optimization to rely on far fewer a priori assumptions, open up to larger search ranges, and include right from the start and in parallel multiple error distributions to find truly global optima, all while completing a full optimization campaign in weeks rather than months. In this paper we present the neural network designs, the deep learning approach, iterative retraining procedures, and demonstrate how these machine learning techniques can be incorporated into existing state-of-the-art optimization workflows with only minimal changes applied to the optimization pipeline itself and none at all to the employed tracking codes.

Abstract In contrast to conventional E-mode resonance accelerators, H-mode DTLs provide for compact linac sections and have been established as highly efficient resonators during the last decades. Thus, H-mode structures are widely applied for heavy-ion acceleration with medium beam energies because of their outstanding capability to provide high acceleration gradients with relatively low energy consumption. To build upon those advantages, an alternating phase focusing beam dynamics layout has been applied to provide for a resonance accelerator design without internal lenses, which allows for eased commissioning, routine operation, maintenance, and potential future upgrades. The features of such a channel are going to be demonstrated on the example of two interdigital H-mode cavities, separated by an external quadrupole triplet. This setup provides for heavy ion (mass-to-charge ratio A / z ≤ 6 $A/z\le 6$ ) acceleration from 300 keV/u to 1400 keV/u and is used as an injector part of the superconducting continuous wave accelerator HELIAC. Hence, this promising approach generally enables effective and compact routine operation for various applications, such as super heavy ion research, material science, and radio biological applications such as heavy-ion tumor therapy.

The problem of signal amplification in a plasma microwave amplifier is considered in the linear approximation and with allowance for nonlinear effects leading to saturation of instability. The solutions of the exact dispersion equation and an approximate dispersion equation used in calculation of parameters of plasma microwave amplifiers are compared. It is shown that the solutions of these equations in the region of high frequencies are significantly different. Nonlinear dynamics of beam–plasma instability in plasma microwave amplifiers is described by a system of differential equations which is obtained by the slowly varying amplitude method and yields an approximate dispersion equation when it is linearized. A method for modifying parameters of a nonlinear system of differential equations to make it consistent with the exact dispersion equation is proposed and the calculation results are demonstrated. [ABSTRACT FROM AUTHOR]

In proton acceleration from laser-irradiated thin foil targets, adding foams on the front surface or connecting a helical coil on the rear surface of the foil has proven to be an effective scheme to enhance proton energy. In this paper, we make the first attempt to incorporate the above two enhancement schemes for laser-proton acceleration by simultaneously adding foams and connecting a helical coil to a thin foil target. By utilizing such integrated targets in the experiment, focused beams were generated. The maximum proton energy and the number of energetic protons are apparently enhanced. Moreover, quasi-monoenergetic peaks were formed at the high-energy end of the spectra. Particle-in-cell plasma simulations and electromagnetic beam dynamics simulations show that the double-layer target not only enhances the energy of protons but also leads to a multiple-fold increase in the number of escaped electrons, which results in an enhanced post-acceleration in helical coil subsequently. [ABSTRACT FROM AUTHOR]

A fundamental understanding of the theory and measurement procedures for characterizing a solenoid is crucial for making a project cost-effective and achieving the desired performance for its use in a LINAC. This paper attempts to comprehend the beam dynamics of charged particles by considering the conservation of canonical angular momentum, which can take on positive, negative, and zero values. The analytical expression to generate a parallel beam using a solenoid is derived. The effect of the final beam size on the values of a solenoid's spherical aberration coefficient and the position of the minimum beam size with respect to the focal length is studied using electron trajectories. A practical procedure to tune the above two parameters of a solenoid is demonstrated by simply modifying the demountable disks connected at each end. A mathematical model is proposed to accurately determine the axis of a solenoid and the magnetic centre using the measured magnetic field data, which is validated experimentally. Several solenoids, used in the 9.5 MeV 10 kW electron LINAC suitable for sterilizing medical products and food irradiation, have been characterised using this procedure. [ABSTRACT FROM AUTHOR]

The nonlinear Schrödinger equation was originally derived in nonlinear optics as a model for beam propagation, which naturally requires its application in cylindrical coordinates. However, that derivation was performed in Cartesian coordinates for linearly polarized fields with the Laplacian Δ ⊥ = ∂ x 2 + ∂ y 2 transverse to the beam z -direction, and then, tacitly assuming covariance, extended to axisymmetric cylindrical setting. As we show, first with a simple example and next with a systematic derivation in cylindrical coordinates for axisymmetric and hence radially polarized fields, Δ ⊥ = ∂ r 2 + 1 r ∂ r must be amended with a potential V (r) = 1 r 2 , which leads to a Gross–Pitaevskii equation instead. Hence, results for beam dynamics and collapse must be revisited in this setting. [ABSTRACT FROM AUTHOR]

In contrast to conventional E-mode resonance accelerators, H-mode DTLs provide for compact linac sections and have been established as highly efficient resonators during the last decades. Thus, H-mode structures are widely applied for heavy-ion acceleration with medium beam energies because of their outstanding capability to provide high acceleration gradients with relatively low energy consumption. To build upon those advantages, an alternating phase focusing beam dynamics layout has been applied to provide for a resonance accelerator design without internal lenses, which allows for eased commissioning, routine operation, maintenance, and potential future upgrades. The features of such a channel are going to be demonstrated on the example of two interdigital H-mode cavities, separated by an external quadrupole triplet. This setup provides for heavy ion (mass-to-charge ratio A / z ≤ 6 ) acceleration from 300 keV/u to 1400 keV/u and is used as an injector part of the superconducting continuous wave accelerator HELIAC. Hence, this promising approach generally enables effective and compact routine operation for various applications, such as super heavy ion research, material science, and radio biological applications such as heavy-ion tumor therapy. [ABSTRACT FROM AUTHOR]

In classical electrodynamics, the well-known Lorentz force law falls short of providing a satisfactory result for the trajectory of point-like charged particles when considering that particle's own self-force. While there have been many historical attempts, Gralla, Harte and Wald developed a new model for classical charged particles that is free from pathologies while being consistent with Maxwell's equations and conserves stress-energy. Expanding upon this approach, we derive a relativistically correct, modified Lorentz force law in vector form, which includes radiation reaction, and spin- and magnetic moment-dependent correction terms, suitable to be included in classical electrodynamics lectures and beam dynamics simulation tools. As by-products we obtain evolution equations for mass, spin angular momentum and the radiated power. We compare the new equations to the classical ones and use the new equations to conduct numerical simulations, showing that the results are free of any nonphysical artifacts, and which might be possible to test in future experiments at particle accelerators. The new equations foster improved insight into beam dynamics. [ABSTRACT FROM AUTHOR]

Tropospheric systems are widely used by military forces as they provide long-distance, real-time communication. Slow-fading propagation loss reduces link availability and limits its data-carrying capacity. Beam pointing dynamics provides knowledge of favorable heights at different times of the day in different seasons and a useful steering range. Beam steering, based on the beam pointing dynamics of the link, can overcome slow fading. The main contributions of this paper are the derivation of a realistic and accurate tropospheric channel model obtained by making important modifications to Dinc's ray-based model. This paper also presents a method for determining beam pointing dynamics using the modified model. Beam pointing dynamics for two different links located in India have been determined in this paper using real-world data obtained from the Indian Meteorological Department. Another significant contribution of the paper is presenting the prospect of dual data streaming on tropospheric links using a fixed beam and a dynamically steered beam, based on the examination of beam pointing dynamics obtained for the two links. The main result presented in this paper is the comparison of powers received from the most favorable heights in a steerable beam system with the powers received in conventional fixed-beam systems for different days of the year. It has been shown that a higher received power can be achieved with beam steering. Another important result shown is the comparison of the achievable data rates for a single fixed-beam system and a dual-beam (one fixed beam and one dynamically steered beam) system. It has been shown that almost double the data rate is achievable in a dual-beam system. The method for the determination of beam pointing dynamics and the possibility of dual data streaming presented in this paper can significantly enhance the availability and capacity of tropospheric links. [ABSTRACT FROM AUTHOR]

Recently, considerable work has been directed at the development of an ultracompact X-ray free-electron laser (UCXFEL) based on emerging techniques in high-field cryogenic acceleration, with attendant dramatic improvements in electron beam brightness and state-of-the-art concepts in beam dynamics, magnetic undulators, and X-ray optics. A full conceptual design of a 1 nm (1.24 keV) UCXFEL with a length and cost over an order of magnitude below current X-ray free-electron lasers (XFELs) has resulted from this effort. This instrument has been developed with an emphasis on permitting exploratory scientific research in a wide variety of fields in a university setting. Concurrently, compact FELs are being vigorously developed for use as instruments to enable next-generation chip manufacturing through use as a high-flux, few nm lithography source. This new role suggests consideration of XFELs to urgently address emerging demands in the semiconductor device sector, as identified by recent national need studies, for new radiation sources aimed at chip manufacturing. Indeed, it has been shown that one may use coherent X-rays to perform 10–20 nm class resolution surveys of macroscopic, cm scale structures such as chips, using ptychographic laminography techniques. As the XFEL is a very promising candidate for realizing such methods, we present here an analysis of the issues and likely solutions associated with extending the UCXFEL to harder X-rays (above 7 keV), much higher fluxes, and increased levels of coherence, as well as methods of applying such a source for ptychographic laminography to microelectronic device measurements. We discuss the development path to move the concept to rapid realization of a transformative XFEL-based application, outlining both FEL and metrology system challenges. [ABSTRACT FROM AUTHOR]

Particle-driven plasma wakefield acceleration (PWFA) exploits the intense wakefields excited in a plasma by a high-brightness driver beam in order to accelerate a trailing, properly delayed witness electron beam. Such a configuration offers notable advantages in achieving very large accelerating gradients that are suitable for applications in particle colliders and photon production. Moreover, the amplitude of the accelerating fields can be enhanced by resonantly exciting the plasma using a multi-pulse driver beam with a proper time structure. Before the injection into the plasma stage, the pulsed electron beam, conventionally termed the comb beam, is usually produced and pre-accelerated in a radio-frequency (RF) linear accelerator (linac). In this pape, we discuss challenging aspects of the dynamics that comb beams encounter in the RF injector stage preceding the plasma. In particular, the examples we analyze focus on the use of velocity bunching to manipulate the time structure of the beam and the impact of dipole short-range wakefields on the transverse emittances. Indeed, both processes crucially affect the phase space distribution and its quality, which are determinant features for an efficient acceleration in the plasma. In addition, the analyses we present are performed with the custom tracking code MILES, which utilizes semi-analytical models for a simplified evaluation of wakefield effects in the presence of space charge forces. [ABSTRACT FROM AUTHOR]

[Objective] Due to the extensive application of self-imaging effects in different fields such as precise measurements, structured light illumination, high-resolution imaging, image processing, and other fields, studies on self-imaging effects, also known as the Talbot effects, have gradually expanded to various physical systems. In the field of optics, it has been theoretically predicted and experimentally demonstrated that self-imaging effects can be realized by using different types of structural beams. Meanwhile, optical beams carrying orbital angular momentum have significant applications in optical manipulation, optical imaging, quantum key distribution, and quantum entanglement. Propagation dynamics of vortex beams are a hotspot in optics research. Focusing on the formation of well-ordered spatial arrays of optical vortices, the effect of different optical vortices on the dynamic behavior of periodic beam evolution would offer novel ideas and ways to systematically understand the evolution dynamic behaviors of vortex beams and the realization of novel structural beams. [Methods] Herein, theoretical and numerical investigations on the propagation dynamics of three different types of vortex Gaussian beams are performed. Classical optical vortex beams, asymmetric power-law optical vortices, beams and symmetric power-law optical vortices beams are considered. Both the intensity distribution and self-imaging distance of transverse periodic Gaussian beams are determined based on the Fresnel diffraction integral theorem. Afterward, the above three types of vortex phases imposed on the initial transverse periodic Gaussian beams are considered, which are chosen as the input beams to directly solve the two-dimensional paraxial wave equation numerically by using the beam propagation method. The dynamic behavior of beam energy evolution is obtained. In addition, the light field distribution is examined in detail, and its self-imaging distance is determined. Comparison of the theoretical and numerical results is performed. [Results] The focus is on the dynamics of three types of optical vortex Gaussian beams modeled by the two-dimensional paraxial wave equation. The simulation results reveal that: 1) All three types of optical vortex Gaussian beams can produce integer and fractional self-imaging effects, where the optical field is periodically self-imaged along a straight trajectory during propagation, and the field pattern of the fractional self-imaging effects shows a half-period shift along the transverse direction. 2) The self-imaging distance of the three kinds of optical vortex Gaussian beam is measured by the reproducing distance of the self-imaging phenomenon generated by the transverse periodic Gaussian beam. 3) The vortex phases for the three optical vortex Gaussian beams are still basically unchanged during the propagation. [Conclusions] The light field structure on the self-imaging plane is composed of well-ordered two-dimensional annular beamlet arrays with ring-shaped fields for all the Talbot planes. The intensity distribution on the self-imaging planes is closely associated with the topological charge and power exponent order of the vortex phase and suffers from some distortions resulting from the weak intensity at the center of the incident beam. For the three types of optical vortex Gaussian beams, the array beam demonstrates various field strength distributions of circular, spiral, and petal shapes. However, the vortex phases for all optical vortex Gaussian beams can remain constant during long propagation distances. According to this principle and method, further research is warranted on the self-imaging effects produced by other structure beams, such as power exponent fractional order optical vortices beams and non-Gaussian periodic beams. [ABSTRACT FROM AUTHOR]

A high-power superconducting linac with an energy of 30 MeV and a beam current of 100 mA has been proposed and designed. The primary challenge lies in beam loss control and a robust lattice structure to ensure stable operation. This paper discusses the physics design study, design principles and simulation results considering machine errors. Extensive multiparticle simulations (a cumulative statistic of 1 × 1 0 5 macroparticles) demonstrated that this linac, operating at 100 mA, could maintain beam losses lower than 1 W/m in error scenarios. [ABSTRACT FROM AUTHOR]

We consider the time dependent Euler–Bernoulli beam equation with discontinuous and singular coefficients. Using an extension of the Hörmander product of distributions with non-intersecting singular supports (L. Hörmander, 1983 [25]), we obtain an explicit formulation of the differential problem which is strictly defined within the space of Schwartz distributions. We determine the general structure of its separable solutions and prove existence, uniqueness and regularity results under quite general conditions. This formalism is used to study the dynamics of an Euler–Bernoulli beam model with discontinuous flexural stiffness and structural cracks. We consider the cases of simply supported and clamped-clamped boundary conditions and study the relation between the characteristic frequencies of the beam and the position, magnitude and structure of the singularities in the flexural stiffness. Our results are compared with some recent formulations of the same problem. [ABSTRACT FROM AUTHOR]

Branched flow is a universal phenomenon in which treebranch-like filaments form through traveling waves or particle flows in irregular mediums. Branched flow of high-current relativistic electron beams (REBs) in porous materials has been recently discovered [Jiang et al., Phys. Rev. Lett. 130, 185001 (2023)]. REB branching is accompanied by extreme beam focusing, up to a hundred times the initial value, at predictable caustic locations. The energy coupling efficiency between the beam and porous material surpasses that in homogeneous targets by two orders of magnitude. This paper examines REB branching, focusing on how beam parameters (e.g., Lorentz factor and density) and characteristics of the porous materials (e.g., pore size, skeleton thickness, and density) influence branching patterns. Analyses of the dynamics of individual beam electrons are also provided. The findings pave the way for further understanding REB branching and its potential applications in the future. [ABSTRACT FROM AUTHOR]

In this paper, the effects of initial curvature and lattice core shape on the bending vibration of sandwich beams are investigated. The three-dimensional (3D) sandwich beam is simulated by combining a two-dimensional (2D) cross-sectional analysis with a one-dimensional (1D) nonlinear beam analysis. The sandwich beam is composed of two identical isotropic faces covering a lattice core. Four different lattice core structures are used to take into account the effect of core unit cell shape on the dynamic properties of the sandwich beam. The nonlinear governing equations of the sandwich beam are Discretized using a time-space scheme. Numerical results show that the lattice unit cell shape affects both in-plane and out of plane stiffness values and hence changes the dynamic behavior of the beam. Furthermore, it is observed that by changing the density ratio of the beam, modes veer away from each other at a specific value of density ratio for specific unit cell types. Moreover, the initial curvature of the beam is shown to affect the dynamics of the beam especially lower modes. Finally, it is obtained that the dynamics of the beam is different when it is initially curved or curved due to an applied end follower moment. [ABSTRACT FROM AUTHOR]

Polymers are ultra-versatile materials that adapt to a myriad of applications, as they can be designed appropriately for specific needs. The realization of new compounds, however, requires the appropriate experimental characterizations, also from the mechanical point of view, which is typically carried out by analyzing the vibrations of beams, but which still have some unclear aspects, with respect to the well-known dynamics of elastic beams. To address this shortcoming, the paper deals with the theoretical modeling of a viscoelastic beam dynamics and pursues the elucidation of underlying how the flexural vibrations may be affected when an axial pre-load, compressive or tensile, is applied. The analytical model presented is able to shed light on a peculiar behavior, which is strongly related to the frequency-dependent damping induced by viscoelasticity. By considering as an example a real polymer, that is, a synthetic rubber, it is disclosed that an axial pre-load, in certain conditions, may enhance or suppress the oscillatory counterpart of a resonance peak of the beam, depending on both the frequency distribution of the complex modulus and the length of the beam. The analytical model is assessed by a finite element model, and it turns out to be an essential tool for understanding the dynamics of viscoelastic beams, typically exploited to experimentally characterize polymeric materials, and which could vary enormously simply through the application of constraints and ensued pre-loads. [ABSTRACT FROM AUTHOR]

The article discusses the upcoming BESSY III light source at the Helmholtz-Zentrum Berlin (HZB) and its potential impact on materials research. BESSY III will provide powerful experimental capabilities for in-situ and operando investigations using soft to tender X-rays, which are crucial for understanding the electronic structure of materials. The facility will feature beamlines covering different energy ranges, specialized end stations, and advanced sample environments. It will also prioritize sustainability in its construction and operation. The article emphasizes the importance of data management, metrology, and collaboration with other research institutions. [Extracted from the article]

Radio frequency quadrupole coolers (RFQCs) are very suitable to cool ion beams with moderate energy spread, typically ions of exotic nuclear species (like $^{132}$ Sn $^{1+}$) as in the Selective Production of Exotic Species project at the Laboratori Nazionali di Legnaro, whose ion source supplies 40 keV ions. Beam dynamics includes ion–gas collisions (with a balance of cooling and diffusion effects), acceleration and deceleration and radiofrequency confinement, which can be supplemented by static magnetic field effects. Insertion of a prototype RFQC in the solenoid of the Eltrap machine is also discussed here, with innovations in beam extraction and in modelling, now also based on stochastic equations. Practical consideration on gas pumping and voltage distribution are also included. Typical limits of RFQC are discussed, with special attention to the extracted beam root mean square emittance, which is shown to strongly depend not only on cooler parameters, but also on extraction optics. [ABSTRACT FROM AUTHOR]

Unusual thermal self‐focusing of two‐dimensional beams in plasma which axis is parallel to the equilibrium straight magnetic field is considered. The equilibrium parameters of plasma determine scenario of a beam divergence (usual or unusual) which is stronger as compared with a flow without magnetic field. Nonlinear thermal self‐action of a magnetosonic beam behaves differently in the ordinary and unusual cases. Damping of wave perturbations and normal defocusing in gases leads to reduction of the magnitude of initially planar perturbations at the axis of a beam. Additional thermal self‐focusing nonspecific for gases occurs in plasma under some condition which counteracts this reduction. The theory and numerical examples concern thermal self‐action of initially focused (defocused) magnetosonic beam. Dynamics of perturbations in a beam is determined by dimensionless parameters responsible for diffraction, damping of the wave perturbations, initial radius of a beam's front curvature, and the ratio of viscous to thermal damping coefficients. [ABSTRACT FROM AUTHOR]

Superconducting (SC) radio-frequency quadrupoles (RFQs) have exhibited outstanding performance in transmitting and accelerating high-current continuous-wave (CW) ion beams. They can complete beam acceleration at a much higher gradient and with much lower power consumption compared with normal conducting (NC) RFQs. In this study, we introduce a novel SC RFQ scheme operating at 162.5 MHz to accelerate 10 mA proton beams from 30 keV to 2.5 MeV. It will be used as a crucial component for a neutron source dedicated to Boron Neutron Capture Therapy (BNCT) and neutron imaging projects. For efficient transmission of proton beams, we selected a relatively high inter-vane voltage of 240 kV, and the beam dynamics design yielded satisfactory results. Subsequently, RF design and multi-physics analysis were carried out to validate the reliability of the design. A 30-centimeter-long cavity was specifically designed for the vertical test and allowed for a thorough evaluation of the performance of the SC RFQ after post-treatments. Additionally, the tuning design of the 30 cm cavity was also carried out. [ABSTRACT FROM AUTHOR]

The results of the Oxygen 5+ beam dynamics simulation in the regular section of a 7,5 MeV/u linear accelerator are presented. Linear accelerator LU-1 consists of several ion sources, RFQ section (Radio Frequency Quadrupole) and two groups of identical IH (Interdigital H-type) cavities. Beam transport between the accelerating sections is done via low energy (LEBT) line, two medium energy MEBT-1 and MEBT-2 lines, and high energy (HEBT) line that transfers the beam to the booster synchrotron or a beam dump. This paper contains the results on Oxygen 5+ A/Z = 3.2 beam dynamics end-to-end simulation in the LU-1 sections (LEBT, RFQ, MEBT-1, MEBT-2 beam transport lines and both groups of IH cavities). [ABSTRACT FROM AUTHOR]

The heavy ion facility for technological applications is developed at the Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences. The booster synchrotron with electron cooling is one of the main parts of the facility. This work presents the beam dynamics simulation with betatron coupling and nonlinearities of the guided magnetic field. The transverse betatron coupling excited by electron cooling solenoid was compensated by the pair of skew quadrupole triplets with antisymmetric supply and located symmetrically relative to the solenoid center. The calculation of the vertical dispersion excited by the magnetic field of toroidal sections of the electron cooler was performed. The accelerator lattice was optimized for minimization of vertical dispersion. Another important factor of the beam dynamics is the tune dependence versus momentum deviation called chromaticity. To correct chromaticity, sextupole magnets are applied. On the other hand, sextupoles excite nonlinear resonances that can lead to significant limitation of the dynamic aperture. The dynamic aperture of the synchrotron was simulated by scanning of horizontal and vertical tunes in conditions of chromaticity and betatron coupling suppression. This method makes it possible to identify dangerous resonances. According to the calculations presented, a scheme with application of six sextupole families are developed. This scheme makes it possible to significantly reduce the influence of most dangerous resonances. The wide area of tunes with a fairly large dynamic aperture for particles with required momentum spread was found in simulations. Selection of the operating point in this particular area makes it possible to reduce the space charge effect on the dynamic aperture. At the chosen operating point, the influence of eddy currents and magnetic fields nonlinearities on the dynamic aperture was investigated. [ABSTRACT FROM AUTHOR]

The structure of a compact X-ray source based on inverse Compton scattering and the beam dynamics in the linac and the storage ring is considered. The features of collective effects in the storage rings of such installations are studied in compaаrison with fourth-generation SR sources. The thresholds of longitudinal microwave instability and transverse instability of coupled modes are calculated. [ABSTRACT FROM AUTHOR]