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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.

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.

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.

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.

The effects of the phase variation, the evolution of the electron beam, the evolution of the radiation intensity, and the higher-order modes due to waveguides on a free-electron laser (FEL) oscillator have been analyzed by using two electron beams of different energies based on the proposed FEL facility which is to be operated in the far-infrared and infrared regions. The three-dimensional (3D) effects on a FEL oscillator due to waveguides and higher-order modes were studied using an extended 3D FEL code with two electron beams that we have developed. The effects of the variation on the amplitude of radiation on the electron beam's emittance and energy spreads were also calculated in the case of waveguide for multi-particle and multi-pass numbers by using a new 3D code. The phase variation, the variation in the beam envelope, the evolution of the amplitude, and power were calculated for the fundamental mode. The results were compared with those of the higher-order modes of the wiggler for various TE and TM modes for determining the FEL's performance which is required for high-quality electron beams.

In this paper, the self-focusing property of an intense circularly polarized laser pulse in hot magnetized plasma is investigated theoretically. First, an envelope equation governing the spot-size of the laser beam for both left- and right-hand polarizations has been derived in the presence of a planar wiggler. Furthermore, non-linear dispersion relation of laser pulse is obtained by using Maxwell’s equations and relativistic fluid momentum equation. The numerical results show that with increasing the wiggler field, strength self-focusing of the right-hand polarization laser pulse is enhanced, while for the left-hand polarization, laser de-focusing is enhanced. In addition, it is shown that with increasing the wiggler frequency, the normalized laser power has an enhancing behavior. Besides, it is found that effect of the wiggler field on the density profile in the right-hand polarization is more prominent.

The development of a high-flux beamline for X-ray footprinting at NSLS-II is presented., Hydroxyl-radical mediated synchrotron X-ray footprinting (XF) is a powerful solution-state technique in structural biology for the study of macromolecular structure and dynamics of proteins and nucleic acids, with several synchrotron resources available to serve the XF community worldwide. The XFP (Biological X-ray Footprinting) beamline at the NSLS-II was constructed on a three-pole wiggler source at 17-BM to serve as the premier beamline for performing this technique, providing an unparalleled combination of high flux density broadband beam, flexibility in beam morphology, and sample handling capabilities specifically designed for XF experiments. The details of beamline design, beam measurements, and science commissioning results for a standard protein using the two distinct XFP endstations are presented here. XFP took first light in 2016 and is now available for general user operations through peer-reviewed proposals. Currently, beam sizes from 450 µm × 120 µm to 2.7 mm × 2.7 mm (FWHM) are available, with a flux of 1.6 × 1016 photons s−1 (measured at 325 mA ring current) in a broadband (∼5–16 keV) beam. This flux is expected to rise to 2.5 × 1016 photons s−1 at the full NSLS-II design current of 500 mA, providing an incident power density of >500 W mm−2 at full focus.

The dynamical stability of electron trajectories of a free-electron laser with a quadrupole wiggler is studied. For this purpose, the numerical computation of Kolmogorov entropy is used. Self-electric and self-magnetic fields are taken into account, and the focusing of the beam is enhanced by an axial magnetic field. A considerable decrease in the dynamical stability of electron trajectories was found when self-fields are considered. Also, it was found that an axial magnetic field can significantly alter the regular trajectories of the electrons.

A superconducting wiggler with a magnetic field of 7 T is installed as an insertion device for three X-ray beamlines with photon energies of more than 30 keV used at the Dortmund Electron Accelerator (DELTA, Germany), a source of 1.5 GeV synchrotron radiation. Each of the two side beamlines is separated from the central one by 15 mrad and all three beamlines use a horizontal aperture of 5 mrad. To meet these requirements, the insertion device must have a period of 127 mm and a magnetic field of 7 T for the vertical aperture of a beam vacuum chamber 10 mm long and a flange-to-flange distance of 2.2 m. A superconducting 22-pole wiggler with a field of 7 T and a period of 127 mm operating in the zero boil-off mode is described. The concept and main approaches to designing the magnetic and the cryogenic systems are presented, along with the main parameters and results from testing the new 7-tesla superconducting wiggler for the DELTA storage ring.

The present analysis develops a novel theory of terahertz radiation generation by beating of two laser beams, incident obliquely on the array of vertically aligned carbon nanotubes (CNTs) in the presence of an external wiggler magnetic field. The array of CNTs behaves as nanoantenna to generate THz radiations. The incident lasers exert a ponderomotive force on the electrons of the CNTs to produce nonlinear oscillatory velocity, which beats with the applied wiggler magnetic field. This beating produces a nonlinear current at (ω2 − ω1, k2 − k1 + k0) which acts as an antenna to produce the THz radiation. We observe that when the beat frequency (ω2 − ω1) lies near the effective plasmon frequency of the CNTs, strong THz radiation is produced due to a resonant interaction of the laser with CNT electrons. The externally applied wiggler magnetic field enhances the efficiency of THz radiation of nanoantenna by providing the necessary momentum to the generated THz radiation. We explore the impact of radius and length of nanotubes on the efficiency of THz generation. The generated THz power is enhanced at an optimum angle of incidence of lasers with an array of CNTs.

Starting from a three-wave interaction system of equations for free-electron lasers in the framework of a quantum fluid model, the full spatio-temporal solution of this set of equations is numerically obtained. Although this quantum fluid model does not take into account the electron recoil, it is accurate enough to model free-electron lasers down to soft X-ray range using a counter propagating optical wiggler and a moderately relativistic electron beam for a table-top compact device. We have shown that the scattered radiation is amplified and divided into sub-pulses while it absorbs energy from the optical wiggler through the negative energy beam plasma mode. Furthermore, the leading pulse gets more energy than the others while the longitudinal waist is reduced and has a shape similar to a “π-pulse” solution from the sine-Gordon equation.

The generation of coherent Terahertz (THz) radiation is studied which is produced from moving the relativistic electron beam through a helical wiggler with axial magnetic field. The relativistic electron beam is modulated via interacts with the beat wave of two laser beams that have frequency difference in THz range. When the modulated relativistic beam of electrons go through the helical wiggler with axial magnetic field, it radiates coherent THz electromagnetic wave as an antenna. In addition, the numerical study has shown the maximum THz power increases with the increasing axial magnetic field power.

We have analyzed the effects of the wiggler error due to the electron beam's emittance, energy spreads, and higher-order modes in a free-electron laser (FEL) oscillator by using two electron beams of different energies based on the proposed FEL facility which is operated at a far-infrared and infrared regions. The three-dimensional (3D) effects in a FEL oscillator due to the wiggler error were calculated and an evaluation of the effect of the beam's emittance and energy spread was performed for the case of the coupled two-beam oscillator for phase shift errors and wiggler errors. The mode construction was studied on the higher-order modes of the wiggler for the various wiggler error parameters for FEL performance which is required for the high-quality electron beam. The radiation intensity at the fundamental mode was calculated for the rms phase shake in wiggler errors with sinus type, constant type, and parabolic type in the two-beam oscillator system using the 3D calculations. The results are compared with those of the fundamental modes without wiggler errors.

Present work focuses on Hermite-cosh-Gaussian (HchG) laser-induced third harmonic generation (THG) in plasma on account of self-focusing. HchG laser beam gets self-focused due to ponderomotive force while propagating in plasma. Interaction of intense laser pulse results ponderomotive force on electrons and induce density perturbation that produces density oscillations at second harmonic frequency. Induced density perturbation beats with quiver velocity of electrons at laser frequency to produce a third harmonic nonlinear current. Application of wiggler magnetic field satisfies the phase matching condition which results resonant THG. Significant enhancement in the efficiency of THG is observed by using HchG laser profile for mode index m = 2. Small variation in decentered parameter also affects the THG efficiency which shows the sensitivity of decentered parameter.

We study the generation of x-rays from the interaction of relativistic electrons with ultra-intense laser pulse either directly or via laser generated ion channels. The laser pulse acts as the accelerator and wiggler leading to an all-optical synchrotron-like x-ray source. The mm sized accelerator and micron-sized wiggler leads to a compact source of high brightness, ultrafast x-rays with applications in relativistic nonlinear optics, ultrafast chemistry, biology, inner-shell electronic processes and phase transitions.

One of the most important devices for the High Energy Photon Source Test Facility project, the 2.6 T 32-pole 3W1 superconducting wiggler, was designed by the Institute of High Energy Physics (IHEP); its magnetic gap is 68 mm, and its storage energy is 286 kJ. It will be installed at the storage ring of the Beijing Electron Positron Collider Upgrade Project at the IHEP to replace the old permanent wiggler. The primary purpose of the cryostat is to create a safe and reliable system and realize long-term operation with zero liquid helium consumption. To maintain liquid helium temperature, four identical two-stage cryocoolers are placed symmetrically at the wiggler ends. The cryostat has only one 60 K thermal shield, which is used to reduce the heat load to the liquid helium vessel. The cryostat has several novel features, including a suspension system with little heat leakage that is self-centered during cooling of the cryostat, a special copper liner and high-efficiency condensers, three pairs of binary current leads, and three-level safety design. The cryogenic system has been cooled three times, and the residual cooling capacity is approximately 0.41 W at 4.2 K without current.

In the present paper, second harmonic generation (SHG) of cosh-Gaussian laser in a magnetized plasma is analyzed. During laser propagation through plasma, electrons acquire the oscillatory velocity and result density perturbation. The density oscillations beat with the oscillatory velocity to produce second harmonic current which drives SHG. Wiggler magnetic field adds the additional momentum to the photons of second harmonic and fulfills the phase matching condition which results in resonant SHG. Wiggler magnetic field also helps to maintain the cyclotron frequency due to which plasma electrons remain confined within the plasma region and results SHG of higher efficiency. Using paraxial approximation, we have derived the equation for the amplitude of SHG and studied its variation for different values of intensity parameter of incident laser, wiggler magnetic field, decentered parameter and plasma density. The efficiency of SHG is significant at higher values of intensity of incident laser, wiggler field, and plasma density as observed in our analysis.

X-ray absorption spectroscopy (XAS) beamlines worldwide are steadily increasing their emphasis on full photon-in/photon-out spectroscopies, such as resonant inelastic X-ray scattering (RIXS), resonant X-ray emission spectroscopy (RXES) and high energy resolution fluorescence detection XAS (HERFD-XAS). In such cases, each beamline must match the choice of emission spectrometer to the scientific mission of its users. Previous work has recently reported a miniature tender X-ray spectrometer using a dispersive Rowland refocusing (DRR) geometry that functions with high energy resolution even with a large X-ray spot size on the sample [Holden et al. (2017). Rev. Sci. Instrum. 88, 073904]. This instrument has been used in the laboratory in multiple studies of non-resonant X-ray emission spectroscopy using a conventional X-ray tube, though only for preliminary measurements at a low-intensity microfocus synchrotron beamline. This paper reports an extensive study of the performance of a miniature DRR spectrometer at an unfocused wiggler beamline, where the incident monochromatic flux allows for resonant studies which are impossible in the laboratory. The results support the broader use of the present design and also suggest that the DRR method with an unfocused beam could have important applications for materials with low radiation damage thresholds and that would not survive analysis on focused beamlines.

A two-bunch scheme to generate high-power, high-repetition-rate THz radiation for pump–probe experiments at LCLS II is studied. The two-bunch beam dynamics, the THz wiggler and radiation are described, as well as the transport system bringing the THz pulses from the wiggler to the X-ray experimental hall., Experiments using a THz pump and an X-ray probe at an X-ray free-electron laser (XFEL) facility like the Linac Coherent Light Source II (LCLS II) require frequency-tunable (3 to 20 THz), narrow bandwidth (∼10%), carrier-envelope-phase-stable THz pulses that produce high fields (>1 MV cm−1) at the repetition rate of the X-rays and are well synchronized with them. In this paper, a two-bunch scheme to generate THz radiation at LCLS II is studied: the first bunch produces THz radiation in an electromagnet wiggler immediately following the LCLS II undulator that produces X-rays from the second bunch. The initial time delay between the two bunches is optimized to compensate for the path difference in THz transport. The two-bunch beam dynamics, the THz wiggler and radiation are described, as well as the transport system bringing the THz pulses from the wiggler to the experimental hall.

The analytical formalism for whistler-pumped FEL amplifiers in collective Raman regime is developed. Compton regime (CR) has also feasible for the low-current gain; however, in practical, it does not exist for reasonable growth rate due to require of extremely high magnetic fields density (i.e., 10–15 T) to operate up to 200–250 GHz frequencies; hence, Raman regime plays an important role with the finite space charged mode only. The dispersive nature of the whistler-pumped FEL amplifiers is sensitive to frequency of electron cyclotron, plasma frequency, and magnetic fields of the amplifiers. The simultaneously of the pumped frequency with strong magnetic fields and plasma frequency should be synchronized for electron cyclotron frequency, which can rapidly increases the wiggler wave number to the radiation of amplification in the slow-whistler mode for high frequencies from millimeter to the sub-millimeter ranges. It is also clear that the background plasma should be lesser than the beam density for the charge neutralization and guiding of the signal into waveguides; hence, the plasma density can also improve the stability of high frequencies. In Raman regime, the growth rate is larger while it decreases as increases the frequency of operations and vice versa. The tapering of an axial field also plays a typical role to raise the efficiency as well as reduction in the length of interaction with axis.

The X-ray fluorescence (XRF) analysis with using synchrotron radiation (SR) is a powerful technique for resolving elemental composition of the different samples with high sensitivity. This technique is suitable for nondestructive multi-elemental analyses of heavy elements such as rare-earth elements. In this paper, the choice of optimal excitation energies for the determination of the trace amounts of the different rare-earth elements (REEs) from La to Lu by the SRXRF method was discussed. The SRXRF spectra have received at the synchrotron radiation (SR) station using radiation from the 9-pole wiggler on VEPP-4M at the Siberian Synchrotron and Terahertz Radiation Center (SSTRC). As samples the Russian and international standards of magmatic rocks (AGV-1, BCR-1, DNC-1, BIR-1, SGD-1A, and G-2) were used. This powerful technique should be useful for nondestructive analyses of rare-earth and heavy elements in geological, geochemical and archaeological samples as well as industrial materials.

We have developed an extended three-dimensional free-electron laser (3D FEL) code with source-dependent expansion to calculate the intensity of the radiation field and the spot size in a free-electron laser oscillator. The effect of the wiggler field errors was evaluated for the case of a planar wiggler generated by a magnet stack with parabolic shaped pole faces by using the extended three-dimensional equations in a free-electron laser oscillator based on the proposed FEL facility which is to be operated in the far-infrared and the infrared regions. The radiation spot size due to the wiggler field errors also have been analyzed for wiggler errors of ΔB/B = 0.0, 0.03, 0.06 and 0.09% at z = 1 m and z = 2 m. The effect of the diffraction of radiation field due to the wiggler field errors of ΔB/B = 0.0 and ΔB/B = 0.09% at 200 passes was evaluated by using the extended 3D code that we developed. The variation of the curvature of the phase front and the effect of the radiation field intensity due to the wiggler field errors were also evaluated for B = 0.5 T and B = 0.7 T with the wiggler error of ΔB/B = 0.09% at 200 passes and the results were compared to those of without errors. The intensity of the radiation, behavior of the radiation spot size and the variation of the curvature of the phase were highly sensitive to the wiggler error of ΔB/B > 0.09%, but were less sensitive to the wiggler errors for ΔB/B< 0.09% in a free-electron laser (FEL) oscillator based on the proposed FEL facility.

The cryostat chiefly consists of external vacuum housing, 60 K shield screens, liquid helium vessel with an SC multipole magnet inside, vacuum chamber (beam duct) with copper liner inside, and four two-stage cryocoolers with a stage temperature of 4.2 K/60 K. Current leads have heat in-leak interception in vacuum using cryocoolers. The helium vessel is suspended with four vertical and four horizontal CFRP (T300) tension rods connected to the external cryostat vessel. These tension rods pass throughout the 60 K shield screens and attach to bolts on the external housing walls and are used for precise alignment of the vertical magnet position.

This paper presents a scheme of electron energy enhancement by employing frequency - chirped lowest order axicon focussed radially polarised (RP) laser pulse in vacuum under the influence of wiggler magnetic field. Terawatt RP laser can be focussed down to ∼5μm by an axicon optical element, which produces an intense longitudinal electric field. This unique property of axicon focused Gaussian RP laser pulse is employed for direct electron acceleration in vacuum. A linear frequency chirp increases the time duration of laser-electron interaction, whereas, the applied magnetic wiggler helps in improving the strength of ponderomotive force v → × B → and periodically deflects electron in order to keep it traversing in the accelerating phase up to longer distance. Numerical simulations have been carried out to investigate the influence of laser, frequency chirp and magnetic field parameters on electron energy enhancement. It is noticed that an electron from rest can be accelerated up to GeV energy under optimized laser and magnetic field parameters. Significant enhancement in the electron energy gain of the order of 11.2 GeV is observed with intense chirped laser pulse in the presence of wiggler magnetic field of strength 96.2 kG.

PROBLEM TO BE SOLVED: To provide a small-sized and economical electron storage ring capable of low emittance operation and being inserted with a mini-undulator or a superconducting wiggler. SOLUTION: An electron storage ring is formed so that three same-shaped first deflection electromagnets 1, 2, 3 arranged in series and two four-pole electromagnets 4, 5 interposed therebetween are used as major elements, that a tripple chromatic bend(TCB), wherein a horizontal beta function βx and a dispersion function η in the center of each of the electromagnets are reduced as much as possible even if the dispersion function at an end of a module becomes a comparatively large value, is used as a first basic module, that, second deflection electromagnets each having a half length of the first deflection electromagnets being used, the electromagnets are arranged in order of the first deflection electromagnet - the four-pole electromagnet - the second deflection electromagnet - the second deflection electromagnet - the four-pole electromagnet - the first deflection electromagnet, that a TCB wherein a dispersion function in each of straight line parts formed between the second deflection electromagnets is made zero is used as a second basic module, and that these basic modules are arranged plurally in series.

The construction of the «Siberian Photon Ring Source», the SKIF synchrotron, in Novosibirsk is underway. At the first stage, six research workstations will be created, most of the devices of which work in a high vacuum. Synchrotron radiation is generated by superconducting Wigglers for two stations. The total radiation power is approaching 49 kW, and the power density on the axis is 92 kW/mrad2. The high energy density of the beam creates quite difficult conditions for the thermal management of optical elements at the workstations. The article presents specific requirements for cooling devices, an overview of the used and promising cooling systems is made, an example of calculating the temperature, stress and strain distribution in a diamond filter with a thickness of 300 microns using the ANSYS Fluent software package is given.

It is shown that an extensive set of accurate ionization-chamber measurements with a primary polychromatic synchrotron X-ray beam transmitted through various filter combinations/thicknesses can be used to quite effectively estimate the absolute flux distribution. The basic technique is simple but the `inversion' of the raw data to extract the flux distribution is a fundamentally ill-posed problem. It is demonstrated, using data collected at the Imaging and Medical Beamline (IMBL) of the Australian Synchrotron, that the absolute flux can be quickly and reliably estimated if a suitable choice of filters is made. Results are presented as a function of the magnetic field (from 1.40 to 4.00 T) of the superconducting multi-pole wiggler insertion device installed at IMBL. A non-linear least-squares refinement of the data is used to estimate the incident flux distribution and then comparison is made with calculations from the programsSPECTRA,XOPandspec.exe. The technique described is important not only in estimating flux itself but also for a variety of other, derived, X-ray properties such as beam quality, power density and absorbed-dose rate. The applicability of the technique with a monochromatic X-ray beam for which there is significant harmonic contamination is also demonstrated. Whilst absolute results can also be derived in this monochromatic beam case, relative (integrated) flux values are sufficient for our primary aim of establishing reliable determinations of the percentages of the various harmonic components.

We present the numerical analysis of optimization of wiggler wave number for density transition based second harmonic generation during laser plasma interaction. Wiggler wave number required for phase matching increases with plasma density and the intensity of pump wave. It is due to the fact that wiggler magnetic field offers the additional angular momentum which is necessary to make the second harmonic generation process resonant. A considerable enhancement in the resonant second harmonic generation of an ultra-short pulse laser in plasma with density transition surrounded by a magnetic wiggler is observed. Density transition in plasma plays a key role in self-focusing which further enhances the harmonic generation of second order in plasma. Also we have examined the effect of magnetic wiggler on the harmonic generation of second order in plasma.

A bent Bragg–Laue monochromator (BLM) is proposed for high-energy X-ray (∼25–60 keV) beamlines. The BLM has the unique feature of bi-directional focusing. A sagittally bent Laue crystal can focus the large horizontal fan of a bending magnet or wiggler source. A meridionally bent Bragg crystal focuses the beam vertically and corrects for the anticlastic bending effects of the Laue crystal. This monochromator geometry relies on the crystal orientations being optimized. It is shown that the focusing condition and Rowland condition can be simultaneously satisfied at a given energy. Detailed ray tracings indicate that a BLM can provide similar energy resolution and higher flux density compared to a sagittally bent double-Laue monochromator configuration. A prototype BLM with a symmetric Bragg crystal and an asymmetric Laue crystal was tested. Matching of the bend radii of the two crystals in the meridional direction was demonstrated. In general, the horizontal acceptance of the sagittally bent Laue crystal is limited by the large curvature. This horizontal BLM acceptance could be increased by translating the Laue crystal along its sagittal bending axis.

We reason that in the free-electron radiation if the transition rate τ is less than the radiation frequency ν, the radiation is of broad-band spectrum whereas if τ ≫ ν, the radiation is of monochromatic. We find that when a weaker magnetic wiggler (MW) is superpositioned on a predominantly strong uniform magnetic field, free-electron two-quantum magnetic-wiggler (FETQMW) radiation takes place. In FETQMW radiation, the MW and the electron’s intrinsic motivity to change its internal configuration through radiation play as two first-order perturbers while the uniform magnetic field acts as the sole zeroth-order perturber. When ΔE≪ hν, where ΔE is the uncertainty in the electron energy produced by transverse wiggling due to the MW in conjuction with a Heisenberg’s uncertainty principle ΔEΔx ~ h and E = (m 2 c 4 + c 2 p 2)1/2, the power of FETQMW radiation cannot exceed hν 2. However, we find that this power cap is lifted by the amount of νΔE when ΔE ≫ hν holds [1,2]. This lift-up of the saturated radiation power is the responsible mechanism for the effective external injection of a 20 kW maser in an electron-cyclotron maser (ECM). We find that an MW-added ECM with radius 5 cm and length 1 m and operating parameters of the present beam technology can yield laser power of 50 MW at the radiation wavelength of 0.001 cm.

We reason based on the concept of stationary plasma fluctuation that in the free-electron laser (FEL), the Coulomb force from the surrounding electrons and the Amperian force arising from the beam current do not disrupt the density-deviation mode driven by the laser field in cooperation with the magnetic wiggler. We adopt the synchronization principle that in the state of a stationary plasma density-wave and laser wave, all electrons arriving at the same position can emit laser photons all together only at t = NT + t o , where N is an integer and T is the laser period. We find that in the FEL, the incident laser radiation acts as a dummy field in net stimulated radiation. Using these findings and noticing a previously-recognized concept that the radiation power from an electron is given by ΔE/T, where ΔE is the amplitude of the net work done by the electron during T [1], we derive the laser gain of a self-launched FEL. The thusly derived gain is in excellent agreement with the measured gain.

In this paper, efficiency enhancement and saturation length reduction of three-dimensional free-electron laser (FEL) operating with harmonically coupled two cold electron beams with different energies was studied. To enhance the efficiency of the facility, method of wiggler tapering was used and prebunching of the lower energy electron beam was considered in order to reduce the saturation length of the system. A wiggler with planar geometry was considered to produce higher harmonics of radiation. Energies of the electron beams were chosen so that the fundamental resonance of the fast beam to be at the third harmonic of the slow beam. A set of nonlinear equations based on the scheme introduced in MEDUSA code, were solved numerically. To consider the effect of wiggler tapering, the magnetic field of the wiggler decreased linearly when saturation of the third harmonic radiation field started. The optimum slope and starting point of the wiggler field were found by successive runs of the simulation code to obtain the maximum radiation power. It was found that after tapering of the wiggler field, the power of up-converted third harmonic radiation enhances dramatically and prebunching of the lower energy beam has significant effect on saturation length reduction of the facility. The introduced schemes can be used in production of high power, short wavelength FELs.

A linearly polarized laser pulse has been employed as a wiggler in a free-electron laser (FEL) in the presence of a plasma background for generating short wavelength radiation down to the extreme ultraviolet ray and X-ray spectral regions. Introducing plasma background in the FEL interaction region would lessen the beam energy requirement and also enhance both the beam current and the electron-bunching process. This configuration affords the possibility of scaling the device to more compact FELs and would have a higher tunability by changing the plasma density and the temperature of the electron beam. Electron trajectories have been analyzed using single-particle dynamics. The effect of plasma density on electron orbits has been investigated. A polynomial dispersion relation considering longitudinal thermal motion has been derived, by employing perturbation analysis. Numerical studies indicate that by increasing plasma density, the growth rate for groups I and II decreases, while the growth rate for group III increases. In addition, the effect of beam temperature and cyclotron frequency on the growth rate has been discussed. It has been found that by increasing the thermal velocity of the electron beam, the growth rate for groups I and III trivially decreases, while it increases for group II orbits. Besides, an increase in cyclotron frequency cause growth enhancement for group I orbits, while it present a growth decrement for group II and III orbits.

The propagation of a high power laser beam, with frequency ω 1 and wave vector k 1 z ˆ , through a semiconductor under chirped pulse effect has been investigated which results in the harmonic generation of second order. When a highly intense beam of laser propagates through a semiconductor under the impact of wiggler magnetic field, the transverse current density starts oscillating with a frequency which is twice of the laser field. Enhancement in the second harmonic generation of chirped pulse laser in semiconductor under the influence of wiggler magnetic field is seen. We have also examined the effect of chirped pulse on power conversion efficiency of the second harmonic generation which increases with the increase of the chirp parameter.

In this paper, a free-electron laser (FEL) growth rate with a laser wiggler in which plasma background is used to generate short wavelengths in x-ray regimes, has been investigated theoretically. A linearly polarized laser pulse, due to having short wiggler periods (inrange) is able to produce coherent radiations in x-ray regions and can be applied as a planar wiggler in a FEL. Phase velocity of the laser pulse in presence of plasma background decreases. In this case, the electron beam can be in synchronism with the laser pulse and enters the interaction region with less energy which leads to producing x-ray pulses by low enegy beams, without requiring high beam energies. This configuration allows obtaining higher frequencies than conventional FELs (with magnetostatic wigglers) for a device. Employing a perturbation analysis for the momentum transfer, continuity, and Maxwell equations, the dispersion relation for system has been derived and the effect of plasma density variation on growth rate of a free electron laser with a laser wiggler and plasma background has been discussed. In addition, cross section of electron trajectories for different values of axial magnetic field has been simulated by using fourth order Runge-Kutta method. Results shows that by increasing plasma density, growth rate for group and decreases, while for group increases

Microbeam Radiation Therapy (MRT) is an emerging cancer treatment modality characterised by the use of high-intensity synchrotron-generated x-rays, spatially fractionated by a multi-slit collimator (MSC), to ablate target tumours. The implementation of an accurate treatment planning system, coupled with simulation tools that allow for independent verification of calculated dose distributions are required to ensure optimal treatment outcomes via reliable dose delivery. In this article we present data from the first Geant4 Monte Carlo radiation transport model of the Imaging and Medical Beamline at the Australian Synchrotron. We have developed the model for use as an independent verification tool for experiments in one of three MRT delivery rooms and therefore compare simulation results with equivalent experimental data. The normalised x-ray spectra produced by the Geant4 model and a previously validated analytical model, SPEC, showed very good agreement using wiggler magnetic field strengths of 2 and 3 T. However, the validity of absolute photon flux at the plane of the Phase Space File (PSF) for a fixed number of simulated electrons was unable to be established. This work shows a possible limitation of the G4SynchrotronRadiation process to model synchrotron radiation when using a variable magnetic field. To account for this limitation, experimentally derived normalisation factors for each wiggler field strength determined under reference conditions were implemented. Experimentally measured broadbeam and microbeam dose distributions within a Gammex RMI457 Solid Water® phantom were compared to simulated distributions generated by the Geant4 model. Simulated and measured broadbeam dose distributions agreed within 3% for all investigated configurations and measured depths. Agreement between the simulated and measured microbeam dose distributions agreed within 5% for all investigated configurations and measured depths.

A method is proposed to control the transverse motion and X-ray emission of an electron beam in a laser driven wakefield by tuning the laser spatial chirp. The dispersion of a transversely chirped laser pulse and the transverse nonuniform refractive index of the plasma channel result in transverse laser centroid oscillations, which leads to periodic transverse oscillations of the laser-driven wake. Electrons accelerated inside the wake also undergo transverse oscillations making wiggler like motion. Both the oscillation period and amplitude can be controlled by tuning the laser chirp, the pulse duration or the plasma channel width. As a result, the far field spectral distributions of the X-ray emission can be flexibly manipulated., 8 pages, 5figures

Electron-beams with a sinusoidal energy modulation have the potential to emit sub-femtosecond x-ray pulses in a free-electron laser. The energy modulation can be generated by overlapping a powerful infrared laser with an electron-beam in a magnetic wiggler. Here we report on a new infrared source for this modulation, coherent radiation from the electron-beam itself. In this self-modulation process, the current spike on the tail of the electron-beam radiates coherently at the resonant wavelength of the wiggler, producing a six-period carrier-envelope-phase (CEP) stable infrared field with gigawatt power. This field creates a few MeV, phase-stable modulation in the electron-beam core. The modulated electron-beam is immediately useful for generating sub-femtosecond x-ray pulses at any machine repetition rate, and the CEP-stable infrared field may find application as an experimental pump or timing diagnostic.

Even though high-quality X and gamma-rays with photon energy below mega-electron-volt (MeV) are available from large scale X-ray free electron lasers and synchrotron radiation facilities, it remains a great challenge to generate bright gamma-rays over ten MeV. Recently, gamma-rays with energies up to MeV level were observed in Compton scattering experiments based on laser wakefield accelerators, but the yield efficiency was as low as $10^{-6}$, owing to low charge of the electron beam. Here, we propose a scheme [1] to efficiently generate gamma-rays of hundreds of MeV from sub-micrometer wires irradiated by petawatt lasers, where electron accelerating and wiggling are achieved simultaneously. The wiggling is caused by the quasistatic electric and magnetic fields induced around the wire surface, and these are so high that even quantum electrodynamics (QED) effects become significant for gamma-ray generation, although the driving lasers are only at the petawatt level. Our full three-dimensional simulations with the KLAPS code [2] show that directional, ultra-bright gamma-rays are generated, containing $10^{12}$ photons between 5 and 500 MeV within 10 femtosecond duration. The brilliance, up to $10^{27}$ photons ${\rm s^{-1}~ mrad^{-2}~ mm^{-2}}$ per 0.1\% bandwidth at an average photon energy of 20 MeV, is the second only to X-ray free electron lasers, while the photon energy is 3 orders of magnitude higher than the latter. In addition, the gamma-ray yield efficiency approaches 10\%, i.e., 5 orders of magnitude higher than the Compton scattering based on laser wakefield accelerators. Such high-energy, ultra-bright, femtosecond-duration gamma-rays may find applications in nuclear photonics, radiotherapy, and laboratory astrophysics. [1]Wei-Min Wang, Zheng-Ming Sheng, Paul Gibbon, Li-Ming Chen, Yu-Tong Li, and Jie Zhang, Collimated ultrabright gamma rays from electron wiggling along a petawatt laser-irradiated wire in the QED regime, PNAS 115 (40), 9911–9916 (2018). [2]W.-M. Wang, P. Gibbon, Z.-M. Sheng, Y.-T. Li, and J. Zhang, Laser opacity in underdense preplasma of solid targets due to quantum electrodynamics effects, Phys. Rev. E 96, 013201 (2017).

Funding: U.K. Science and Engineering Research Council under Grant No. EP/N028694/1 (R.A.C.). In the present analysis, we study the dynamics of charged particles under the action of slowly modulated electromagnetic carrier waves. With the use of a high-frequency laser mode along with a modulated static magnetic wiggler, we show that the ensuing total field effectively acts as a slowly modulated high-frequency beat-wave field typical of inverse free-electron laser schemes. This effective resulting field is capable of accelerating particles in much the same way as space-charge wake fields do in plasma accelerators, with the advantage of being more stable than plasma related methods. Acceleration occurs as particles transition from ponderomotive to resonant regimes, so we develop the ponder- omotive formalism needed to examine this problem. The ponderomotive formalism includes terms that, although not discussed in the usual applications of the approximation, are nevertheless of crucial importance in the vicinity of resonant capture. The role of these terms is also briefly discussed in the context of generic laser-plasma interactions. Postprint

Ultra-fast synchrotron radiation emission can arise from the transverse betatron motion of an electron in a laser plasma wakefield, and the radiation spectral peak is limited to tens of keV. Here, we present a new method for achieving high-energy radiation via accelerated electrons wiggling in an additional laser field whose intensity is one order of magnitude higher than that for the self-generated transverse field of the bubble, resulting in an equivalent wiggler strength parameter K increase of approximately twenty times. By calculating synchrotron radiation, we acquired a peak brightness for the case of the laser wiggler field of 1.2 × 1023 ph/s/mrad2/mm2/0.1%BW at 1 MeV. Such a high brilliance and ultra-fast gamma-ray source could be applied to time-resolved probing of dense materials and the production of medical radioisotopes.

Physical review accelerators and beams 22(7), 071302 (2019). doi:10.1103/PhysRevAccelBeams.22.071302, Published by American Physical Society, College Park, MD

The 2.0 T superconducting (SC) Wiggler on the CLSI Hard X-ray Micro Analysis (HXMA) beamline [1-2] ran at a field of 1.9 Tesla during normal operation, lower than the design specification. After ten years of operation, CLSI experienced significant downtime and wiggler magnetic field decreasing due to frequent breakdowns at the cryogenic system [3]. There were total of three emergency repairs at the cryo-cooler and cryo-compressor in 2015. The magnetic field at the Wiggler had to reduce from its normal operation field of 1.9 Tesla to 1.7 Tesla to maintain the operation of the storage ring and HXMA beamline during most time in 2016 due to one of the 4.2K cryo-cooler reaching its limit temperature. The cryogenic system was not reliable and became a risk of extended beamline shutdown. The operating cost of the HXMA wiggler had been very high due to frequent cryo-cooler failures and high liquid helium consumption level. Wiggler upgrades were installed in spring, 2017 including a replacement of the entire cryogenic system from Leybold to Sumitomo [3]. The associated components were also replaced by Budker Institute of Nuclear Physics (BINP) with a new design at cold fingers (gilded pins) and design modifications at the current lead assemblies, the shield cryo-cooler housings and the central throat assembly. The operation temperatures and pressure inside the wiggler cryostat have reduced dramatically after this replacement and modifications. There is no liquid helium consumption and the wiggler has been running at a higher magnetic field of 2.2 Tesla compared to the initial design specification of 2.0 Tesla since this upgrade. The HXMA beamline performance has improved in overall at operation reliability, stability, flex and beam quality.

Microbeam radiotherapy (MRT) appears to target tumour cells while sparing normal healthy cells. However, it is in its preclinical stage at present. Clinical trials of MRT can be done in the Imaging and Medical Beamline (IMBL) of the Australian Synchrotron provided that the dose rate deliverable by the X-ray beam in Hutch 3B of the IMBL, where the required patient positioning equipment is located, is sufficiently high for MRT. At present the deliverable dose rate there is only 75 Gy s − 1 . However, a deliverable dose rate of between and including 375 Gy s − 1 and 750 Gy s − 1 is required for doing MRT clinical trials in Hutch 3B due to the irradiation profile inherent to MRT. The height of the focused beam in Hutch 3B must also be between and including 1.0 mm and 10 mm. A kinoform compound refractive lens (kinoform CRL) made of [ 3 . 5 × 1 0 18 P atoms c m − 3 ]-doped Si is proposed to be used in the Scenario where the X-ray beam, produced by a superconducting multipole wiggler source (SCMPW) operating at a maximum magnetic field of 4.000 T, is filtered by 0.6 mm of diamond before reaching the kinoform CRL. This is the Diamond-Optic Scenario. In this Scenario, the dose rate deliverable in Hutch 3B using the optic ranges from 380 Gy s − 1 to 1300 Gy s − 1 with beam heights ranging from 3.55 mm down to 1.0 mm, respectively. Also, the weighted average photon energies of the beam in Hutch 3B in this Scenario are almost entirely suitable for MRT in the IMBL. The X-ray beam in this Scenario can heat the P-doped Si optic to a few hundred degrees Kelvin above the hypothesised melting point of the P-doped Si due to its high power density. Therefore, the optic must be cooled lest it melt. The Diamond-Optic Scenario is not used routinely in the IMBL due to its excessive power. A variation of the Diamond-Optic Scenario, namely that the kinoform CRL be placed before sensitive components instead of after them is proposed for the routine use of this Scenario.