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Efficiency enhancement in a two-stream Free Electron Laser (FEL) by a tapered wiggler prior to saturation regime is treated. Wave-particle interaction is described by a set of nonlinear coupled differential equations in 1D approximation. The scaled vector potential correspond to the out-put power is plotted versus scaled axial distance. It was found, that, the output power was enhanced to a level of almost 51.79%. Bunching parameter was plotted and compared with the case of un-tapered wiggler field. It is found, that, bunching parameter increased when tapering of the wiggler is executed. Bunching of the electrons in a phase space is shown, too.

Temperature effects on the electron trajectory and growth rate are investigated for a two-stream free-electron laser (FEL) with a helical wiggler along with a guide magnetic field. Both longitudinal and transverse components of the beam temperature are including providing the full beam temperature effects. Two different cases namely, conventional and reversed guide field are considered. Based on the fluid theory, the dispersion relation for the right hand polarized of the electromagnetic wave, including the important influence of temperature is obtained and solved numerically. Two resonances occur in this model: FEL and two-stream FEL (TS-FEL) resonances. It is shown that both of the peak growths of the resonances are reduced due to temperature. However, peak growth rates are substantially affected owing to transverse component of the beam temperature. The result shows, in the case of a reversed guide field the TS-FEL resonance has low thermal sensitivity with respect to the conventional guide field.

During the last decade, Budker Institute of Nuclear Physics (BINP) manufactured nine multipole superconducting wigglers on the basis of NbTi superconductor. These wigglers are operating at various synchrotron radiation centers worldwide. High magnet parameters were achieved due to using NbTi wire of high NbTi/Cu ratio, up to a factor of two, and by grading the current density in the coils. So, further increase in the magnet parameters is limited by the properties of NbTi conductor. Another important feature of the BINP wigglers is the magnet design, with superconducting coils manufactured separately and connected with a splicing resistance of well below 0.1 nΩ at an operating current of about 1 kA. That yields significant decrease in the heat load on cryocoolers because the total amount of splicings in one wiggler exceeds 200. The existing demand in superconducting wigglers and undulators for higher magnet parameters can be realized by using Nb3Sn wire. The ultimate aim of the on-going work at BINP is to make an Nb3Sn superconducting wiggler with separate coils, the terminals of which will be connected by NbTi wires with low splicing resistance, below 0.1 nΩ. During assembling of such a wiggler, these coils will be connected via NbTi terminals by the technology available at BINP. This article reports on first results of testing five samples of Nb3Sn-NbTi wire splicing. The experimental setup is described. The samples are two-turn loops made of Nb3Sn and NbTi wires. The samples were charged by currents of up to 500 A, and the resistance of these superconducting wire connections was evaluated from the current decay using a Hall sensor. All samples have demonstrated very low resistance, estimated as several Ohm.

The paper describes the new X-ray imaging resources, including micro-computed tomography (CT), phase-contrast CT, low-temperature CT and time-resolved topography, that are available at beamline 07 of the SAGA Light Source., The SAGA Light Source provides X-ray imaging resources based on high-intensity synchrotron radiation (SR) emitted from the superconducting wiggler at beamline 07 (BL07). By combining quasi-monochromatic SR obtained by the newly installed water-cooled metal filter and monochromatic SR selected by a Ge double-crystal monochromator (DCM) with high-resolution lens-coupled X-ray imagers, fast and low-dose micro-computed tomography (CT), fast phase-contrast CT using grating-based X-ray interferometry, and 2D micro-X-ray absorption fine structure analysis can be performed. In addition, by combining monochromatic SR obtained by a Si DCM with large-area fiber-coupled X-ray imagers, high-sensitivity phase-contrast CT using crystal-based X-ray interferometry can be performed. Low-temperature CT can be performed using the newly installed cryogenic system, and time-resolved analysis of the crystallinity of semiconductor devices in operation can be performed using a time-resolved topography system. The details of each instrument and imaging method, together with exemplary measurements, are presented.

Second harmonic generation (SHG) using intense Hermite-Gaussian laser beam (HGLB) propagating through the plasma for mode-indices m = 0 and m = 1 is reported in the present work. Ponderomotive force induced density perturbation beats with the oscillatory velocity of electrons at incident laser frequency, generate the second harmonic nonlinear current that give rise to SHG. Using paraxial approximations, we have derived the coupled equations for the beam width parameter of HGLB and second harmonic's normalized amplitude. Resonance condition is obtained by considering wiggler magnetic field which providing an extra momentum to the second harmonic photon and this result a significant increase in the amplitude of SHG. Our analysis shows the prominent rise in normalized amplitude of second harmonic on increasing the value of the intensity of fundamental laser pulse, normalized wiggler magnetic field and normalized density of plasma. It is notified that the gain of SHG is more prominent for m = 1. Dependency of laser and plasma parameters on SHG is also reported in the current work.

A new diffraction beamline for materials science has been built at the Canadian Light Source synchrotron. The X-ray source is an in-vacuum wiggler with a 2.5 T peak magnetic field at 5.2 mm gap. The optical configuration includes a toroidal mirror, a single side-bounce Bragg monochromator, and a cylindrical mirror, producing a sub-150 µm vertical × 500 µm horizontal focused beam with a photon energy range of 7–22 keV and a flux of 1012 photons per second at the sample position. Three endstations are currently open to general users, and the techniques available include high-resolution powder diffraction, small molecule crystallography, X-ray reflectivity, in situ rapid thermal annealing, and SAXS/WAXS. The beamline design parameters, calculated and measured performance, and initial experimental results are presented to demonstrate the capabilities for materials science.

In this paper, the electron acceleration and its relativistic dynamics in an ion-channel formed due to the laser pulse propagation through the plasma and under influence of the ion channel space-charge and a heliacal wiggler as well as the oblique magnetic field have been investigated. The equations for investigation of the electron dynamics are the tree-dimension Lorentz equations. For analytical analysis of the obtained equations, a three-dimension single particle code and forth order Runge-Kutta method is used as well. The electron energy gain and the relativistic electron dynamics drastically are affected by the ion-channel potential and the helical wiggler and also the external oblique magnetic field. The results of this paper can be significant in the selection of the appropriate parameters for plasma-based accelerators design.

At the Institute of Nuclear Physics, a nine-pole hybrid wiggler is developed and successfully installed on the VEPP-4 accelerator complex. The nine poles of the wiggler are electromagnets with iron cores. To achieve the largest field, permanent magnets with a residual induction of 1.2 T are installed between the wiggler poles. Such a combination of electromagnets and permanent magnets made it possible to achieve a maximum magnetic induction of 1.9 T, with an interpolar gap of 30 mm. Currently, at the Siberian Center of Synchrotron and Terahertz Radiation, several research methods using the “hard” X-ray range (50–250 keV) based on radiation from a nine-pole wiggler are being certified. For example, using this radiation, the X‑ray imaging of fast processes, X-ray computed tomography, X-ray fluorescence analysis, and X-ray diffraction studies are carried out. A brief review of these studies is presented.

An investigation of the damping wiggler effect to reduce the emittance in the Pohang Accelerator Laboratory (PAL), a fourth-generation storage ring (4GSR) that uses a multi-bend achromat, is presented. A 4GSR lattice which has reduced emittance and increased dynamic aperture to amplify the synergy with two existing light sources (PLS-II and PAL-XFEL) at PAL is described.

The influence of axial magnetic field and self-fields in the electron gas column and electron beam with elliptical cross section is investigated. Further effects of cross section demotions and beam...

High Energy Photon Source-Test Facility (HEPS-TF) is a pre-research project for the construction of high energy synchrotron radiation source in the 12th five-year plan period. The purpose is to research the key technology and develop the key equipment of high energy synchrotron radiation source. Superconducting 3W1 magnet is the first self-developed superconducting wiggler magnet in China, and it is also one of the key research topics of HEPS. The author has completed a new digital closed-loop control algorithm for the superconducting 3W1 magnet with large load time constant and the nonlinear characteristics of inductance increasing with current, namely three-branch structure algorithm. In the face of the rapid development of high energy accelerator technology, the application of intelligent technology has become an inevitable development trend in the field of accelerator magnet power supply technology. Although the digital control of accelerator magnet power supply has been widely used, it is the first time to apply the new closed-loop control algorithm to realize fast adjustment and precision tracking in accelerator superconducting magnet power supply in China. According to the nonlinear characteristics of inductance and output current of superconducting magnet, a new digital closed-loop control algorithm for the load of superconducting magnet power supply with large time constant is proposed. This algorithm is quite different from the traditional algorithm and can attain the independent tracking and adjustment of the control target. Finally, by testing the ripple, error and stability of superconducting 3W1 magnet power supply, the correctness, practicability and reliability of power supply system as well as the digital control algorithm are verified. The results provide a new idea for the control of accelerator magnet power supply.

Superconducting multipole insertion devices (wigglers and undulators) used to generate synchrotron radiation significantly increase the photon flux, especially in the hard spectral region. Over the past 35 years, more than 25 superconducting wigglers for leading centers of synchrotron radiation have been created at the BINP. A cryogenic system based on cryocoolers has been developed, which makes is possible to operate superconducting insertion devices for several years without consuming liquid helium. In this paper, the characteristics of various superconducting insertion devices created at the BINP are presented. The design features and recent advances in the development of the magnetic and cryogenic system with liquid and indirect cooling are discussed.

This article investigates the effects of ion-channel guiding, axial magnetic fields, helical wiggler magnetic fields (HWMFs), and self-fields on trajectories of the elliptical relativistic electron beam. Two equations for the average axial velocity and the function $\Phi $ are calculated for an electron in the considered fields by solving the motion equation. In the meantime, the effects of elliptical cross section demotions and elliptical electron beam density are also studied. The results are compared in the limit that the elliptical electron beam is converted to a circular electron beam, which have also been graphically presented. It is shown that in the considered conditions, in the case of the elliptical beam, and for spatial cases, there are three types of trajectories. This result is different from the case circular beam because in the case circular beam, there are two types of trajectories. It means that in the case of the elliptical cross section, there are two resonance frequencies of the orbits. Moreover, the resonant frequency of the transverse velocity in the circular beam case is within two resonant frequencies in the elliptical beam case. Furthermore, it has been indicated that for special cases, with increasing $\bar {\omega }_{p} $ , the resonance frequencies of transverse velocity tend toward higher values of $\bar {\omega }_{i} $ . Finally, the conditions of stability of electron orbits in the elliptical electron beam are investigated by considering HWMF. Furthermore, a detailed analysis of the gain equation in an FEL with elliptical electron beam is presented. The obtained gain for an FEL together with a relativistic electron beam with elliptical cross section is compared to the maximum gain for an FEL together with a relativistic electron beam with circular cross section. It is shown that with increasing the ratio of the semimajor to semiminor axes of the beam cross section, the ratio of the gain of the elliptical electron beam increases compared to when a circular electron beam is used for the group I orbits, while for group II orbits the gain decreased, but in special conditions for group II orbits the gain increased. We investigated a study more precisely on the stability of electron orbits of this free-electron laser in the Appendix.

The Iranian Light Source Facility (ILSF) is a 3-GeV third-generation synchrotron radiation laboratory in the basic design phase. The storage ring (SR) is based on a five-bend achromat (5BA) lattice, which provides ultra-low horizontal emittance of 0.27 nm rad. It is recommended to use short-length wigglers for hard x-ray generation because of the ILSF storage ring straight section limitations. This article describes the magnetic design and optimization of the three-pole wiggler and its beam dynamics effects on the SR lattice that have been investigated for the ILSF. The 3D modeling and flux calculations have been carried out by the Radia, SPECTRA and SRW Codes.

Increasing the output power of a long-wavelength free-electron laser (FEL), despite the destroying effects of beam energy spread, is studied using the optimal pre-bunching of the thermal electron beam along with the optimal tapering of the planar wiggler magnetic field. A set of self-consistent coupled nonlinear differential equations in three dimensional that describe the evolution of radiation and electron beam in the interaction zone are solved numerically by the Runge–Kutta method. The axial energy spread is considered and it degrades the FEL performance by reducing the saturation power and increasing the saturation length. To compensate these destroying effects, the optimum function or degree of electron beam pre-bunching and optimum parameters of wiggler tapering are found by the successive runs of the simulation code.

Hybrid photon-counting detectors are widely established at third-generation synchrotron facilities and the specifications of the Pilatus3 X CdTe were quickly recognized as highly promising in charge-density investigations. This is mainly attributable to the detection efficiency in the high-energy X-ray regime, in combination with a dynamic range and noise level that should overcome the perpetual problem of detecting strong and weak data simultaneously. These benefits, however, come at the expense of a persistent problem for high diffracted beam flux, which is particularly problematic in single-crystal diffraction of materials with strong scattering power and sharp diffraction peaks. Here, an in-depth examination of data collected on an inorganic material, FeSb2, and an organic semiconductor, rubrene, revealed systematic differences in strong intensities for different incoming beam fluxes, and the implemented detector intensity corrections were found to be inadequate. Only significant beam attenuation for the collection of strong reflections was able to circumvent this systematic error. All data were collected on a bending-magnet beamline at a third-generation synchrotron radiation facility, so undulator and wiggler beamlines and fourth-generation synchrotrons will be even more prone to this error. On the other hand, the low background now allows for an accurate measurement of very weak intensities, and it is shown that it is possible to extract structure factors of exceptional quality using standard crystallographic software for data processing (SAINT-Plus,SADABSandSORTAV), although special attention has to be paid to the estimation of the background. This study resulted in electron-density models of substantially higher accuracy and precision compared with a previous investigation, thus for the first time fulfilling the promise of photon-counting detectors for very accurate structure factor measurements.

This article reports the design, three-dimensional magnetostatic simulation results, coil fabrication, assembly, and low-temperature test results of a C-frame, iron-dominated high-temperature superconductor dipole magnet for ultra high vacuum magnetic-sensitive spectroscopy techniques at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. The magnet is required to provide fields up to ~1 T along two spatial directions. With an added capability to rotate about its vertical axis of symmetry, the magnet system is capable of delivering field along all three principal axes. The combination of this magnet and fast-switched, elliptically polarized soft X-rays produced by the NSLS elliptically polarized wiggler forms the basis for an excellent tool for polarization-sensitive studies of magnetic materials. The prototype magnet consists of a set of pancake coils fabricated from BSCCO tape reinforced with stainless steel. Those pancake coils are clamped in a low-carbon AISI 1006 grade steel pole and yoke assembly. For testing purposes, a cold He gas environment provided cooling the superconducting magnet to subtransition temperatures; for operation in an ultra high vacuum endstation environment, cooling can be provided by an external cryocooler. The low-temperature tests establish the safe-operating parameters needed to achieve the target magnetic field values. The measured magnetic field values are in close agreement with the magnetic simulation results, thereby confirming that the magnet design fulfills the performance requirements. The final section of this article lists some suggestions to improve the magnet performance.

The results of synchrotron-radiation experiments, carried out at the VEPP-4M electron-positron collider in a wide energy range from 10 eV to 200 keV, are presented. To increase the radiation intensity, the electron-beam energy in the VEPP-4M accelerator ring is raised from 4 to 4.5 GeV. To carry out experiments in the high-energy range of synchrotron radiation, a new multipole hybrid wiggler, producing a field of 1.9 T, is installed at the accelerator ring. A method for calibrating the energy of electrons in the accelerator using a laser polarimeter is discussed.

Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand 13th International Particle Accelerator Conference, IPAC'22, Bangkok, Thailand, 17 Jun 2022 - 22 Jun 2022; [Geneva] : JACoW Publishing, Geneva, Switzerland 25-29 (2022). doi:10.18429/JACoW-IPAC2022-MOIYSP2, In next-generation synchrotron radiation sources targeting extremely low emittance around the so-called diffraction limit, the Touschek and intrabeam scattering (IBS) effects are important factors determining the performance of the facility. As the emittance decreases, the bunch volume decreases and the Touschek beam lifetime also decreases. However, this downward trend in beam lifetime is expected to turn to increase in the emittance region below a certain threshold. Since this threshold is determined by the emittance at equilibrium including the IBS effect, a self-consistent treatment is necessary for a correct and unified understanding of the beam characteristics. In currently operating facilities, such as MAX-IV, or in next-generation light sources under construction or in the planning stages, it is expected that such effects may be observed depending on the operating conditions. This talk will be reviewing Touschek and IBS Effects in terms of how these effects limit the ring performance., Published by JACoW Publishing, Geneva, Switzerland, [Geneva]

Second-harmonic generation of the relativistic self-focused chirped laser pulse in plasma has been studied with the exponential plasma density ramp profile in the presence of a planar magnetostatic wiggler. It is evident that the exponential plasma density ramp is helpful in enhancing second-harmonic generation as, with the introduction of the exponential plasma density ramp, self-focusing becomes stronger and hence, it leads to enhance the harmonic generation of the second order in the plasma. Also, it is observed that the efficiency of second-harmonic generation enhances significantly with an increase in the value of the chirp parameter. Further, the magnetostatic wiggler helps in enhancing the harmonic generation of the second order. This is due to the fact that dynamics of the oscillating electrons is altered due to the Lorentz force which, in turn, modifies the plasma wave and, hence, results in the efficient second-harmonic generation.