Diffraction-limited Storage Rings Research Articles

Studies of round beam at HEPS storage ring by driving linear difference coupling resonance

Strong intra beam scattering (IBS) effect and short Touschek lifetime become common issues for ultra-low-emittance storage ring (USR). One efficient approach to reduce these effects is operating such a machine under round-beam mode, a beam with equal horizontal and vertical emittance. Operating on the coupling resonance to obtain round beam will be most likely the method of choice for many of the future diffraction limited storage ring light sources. In this paper, we carried out a systematic study on round beam generation by driving linear difference coupling resonance using skew quadrupoles with same phase difference between horizontal and vertical planes. Theoretical analysis and application of this method at High Energy Photon Source (HEPS) storage ring are presented. Based on the simulation results of HEPS, we find that round beam can effectively mitigate the horizontal emittance growth due to IBS and increase the Touschek lifetime. Furthermore, the dynamic aperture is still be accommodated using on-axis injection when introducing reasonably skew quadrupole fields along the ring and closing to the coupling resonance to achieve round beam.

Physics issues of the diffraction-limited storage ring light source

<p indent=0mm>The synchrotron radiation light source based on electron storage ring is the most widely used high-performance X-ray source in the field of basic scientific research in the 20th century, and has undergone three generations of development. One important direction of the new generation light source, i.e., the fourth generation light source, is the so-called diffraction-limited storage ring (DLSR) light source. DLSR, with ultra-high average brightness, high repetition frequency, multi-user, high stability, complementary to the free electron laser (FEL), has a great development in recent decades. By adopting lattice design based on compact multi-bend achromats (MBAs), DLSR allows to achieve one or two orders of magnitude lower emittance approaching the diffraction limit of X-rays, and much higher brightness and coherence than available in the third generation light source, while inheriting the high brightness, multi-user and high stability advantages of existing ring light sources. In this paper, the progress made in the last few decades in physics design and optimization of the DLSR, especially on the ultralow-emittance lattice and injection schemes, will be overviewed. To achieve an ultralow emittance, lattice structures of standard MBA and hybrid MBA, and novel magnets of high-gradient quadrupole, antibend, longitudinal gradient dipole and complex bend, have been proposed. To obtain optimized beam dynamics in a DLSR, theoretical and numerical methods have been developed to date. Due to the fact that the nonlinearities are extremely high in a DLSR and the nonlinear dynamics is greatly coupled with the linear optics, the most effective and most commonly used way is global and stochastic optimization of the ring performance evaluated by numerical tracking. To deal with the challenges of injecting to a DLSR with small dynamic acceptance, different injection schemes, such as, pulsed multipole injection, on-axis swap-out injection and on-axis longitudinal injection, have been proposed. Collective effects, especially the intra beam scattering and the Touschek effects, become significant as emittance decreases, requiring methods of bunch lengthening and transverse feedback to ensure the stability of the particle motion at a high beam current. Besides, a few developing topics in DLSR physics will be discussed. Machine learning, the method of transferring disorder data into useful information, is an important branch of artificial intelligence, and has been used in accelerator control system and beam commissioning. This method would be very useful and helpful in the design and optimization, initial commissioning and daily operation of a DLSR. A rational combination of machine learning and multi-objective optimization algorithm, like multi-objective genetic algorithm and multi-objective particle swarm algorithm, can effectively improve the optimization performance, and has been successfully applied in nonlinear optimization of light sources. In addition, improving the performance of synchrotron radiation by combining the beam physics of DLSR and the principle of FEL is one developing research topic which might be able to provide base for further development of the DLSR. Combined with bypass and transverse gradient undulator, high gain FEL could be achieved in the storage ring. Besides, double ring light source, divided into two loops, the inner ring is DLSR, and the other is FEL with more long straight sections, was proposed to improve the utilization rate of the beams.

Development of a stripline kicker for the Hefei Advanced Light Facility

A fast kicker is a significant component for on-axis injection of the new generation synchrotron light source with ultralow emittance. The Hefei Advanced Light Facility (HALF) plans to be a fourth-generation diffraction limited storage ring in the future. The preliminary research work is proceeding smoothly. On-axis longitudinal injection scheme is under consideration for the beam accumulation and has not yet been decided. This paper mainly introduces the development of a stripline kicker optimized for this injection scheme. The kicker, combined with a high-voltage pulse generator, can provide a deflection field for the injected bunch and making it completely transparent to circulating bunches without disturbing them. The structure was simulated by CST. The design results were judged by S-parameters and TDR. The S-parameters of the kicker were measured by a network analyzer, and the reliability of the simulation results was verified by comparing the measured and simulated results. The prototype was tested with a high-voltage pulse generator, and the change of the pulse in the prototype was obtained.

Ptychographic characterization of a coherent nanofocused X-ray beam.

The NanoMAX hard X-ray nanoprobe is the first beamline to take full advantage of the diffraction-limited storage ring at the MAX IV synchrotron and delivers a high coherent photon flux for applications in diffraction and imaging. Here, we characterize its coherent and focused beam using ptychographic analysis. We derive beam profiles in the energy range 6-22 keV and estimate the coherent flux based on a probe mode decomposition approach.

Time Resolved in situ X-Ray Tomographic Microscopy Unraveling Dynamic Processes in Geologic Systems

X-ray tomographic microscopy is a well-established analysis technique in different fields of the Earth Sciences to access volumetric information of the internal microstructure of a large variety of opaque materials with high-spatial resolution and in a non-destructive manner. Synchrotron radiation, with its coherence and high flux, is required for pushing the temporal resolution into the second and sub-second regime and beyond, and therefore moving from the investigation of static samples to the study of fast dynamic processes as they happen in 3D. Over the past few years, several hardware and software developments at the TOMCAT beamline at the Swiss Light Source contributed to establishing its highly flexible and user-friendly fast tomography endstation, making a large variety of new dynamic in situ and operando investigations possible. Here we present an overview of the different devices, including an in-house developed detector, a new highly efficient macroscope and a programmable fast rotation stage. Their tight interplay and synchronization are key for lifting experimental design compromises and follow dynamic processes with high spatial and temporal resolution unfolding over prolonged periods of time, as often required by many applications. We showcase these new capabilities for the Earth Sciences community by presenting three different geological studies, which make use of different sample environments. With a tri-axial deformation rig, chemo-mechanical-hydraulic feedbacks between gypsum dehydration and halite deformation have been studied, while the spatio-temporal evolution of a solute plume has been investigated for the first time in 3D with a flow cell. A laser-based heating system available at the beamline provides access to the high temperatures required to address bubble growth and collapse as well as bubble-bubble interaction and coalescence in volcanological material. With the integration of a rheometer, information on bubble deformation could also be gained. In the near future, upgrades of most large-scale synchrotron radiation facilities to diffraction-limited storage rings will create new opportunities, for instance through sub-second tomographic imaging capabilities at sub-micron length scales.

Design Status of DESY IV – Booster Upgrade for PETRA IV

In PETRA IV project the on-axis injection scheme is preferred since there is no sufficient dynamic aperture for off-axis injection in ultra low emittance storage rings. The challenge is the frequent preparation the injected bunches with the smaller emittance and larger intensity. The current injector complex including the accumulator and booster does not fulfill the requirements and thus will need refurbishments. The injector upgrade option chosen will be composed of an upgraded electron gun, a higher energy LINAC, and the new booster synchrotron DESY IV which has smaller emittance. DESY IV will be located in the existing tunnel of the current booster DESY II. The design of the lattice and some simulation results are addressed in this article.

Design and simulation of thin eddy-current septum for injection of diffraction limited storing ring

Ultra-low emittance in Diffraction Limited Storage Ring (DLSR) usually has small Dynamic Aperture (DA), which makes the traditional off-axis injection inadequate. Fast kickers together with thin septum magnets or direct current lambertsons could support on-axis injection for closely-spaced bunches with small DA. Thin eddy-current septum prototype had been designed for injection with laminated silicon steel sheets as magnet core. Theoretical analysis and transient simulation had been carried out within OPERA software. Due to the minimum thickness of the septa is only 1 mm, several optimization approaches had been applied, such as shielding with strongly paramagnetic material and exciting with full cycle driving pulse, to satisfy the requirement that the leakage field is less than 0.1% with respect to the main one.

A shared vision for macromolecular crystallography over the next five years.

Macromolecular crystallography (MX) is the dominant means of determining the three-dimensional structures of biological macromolecules, but the method has reached a critical juncture. New diffraction-limited storage rings and upgrades to the existing sources will provide beamlines with higher flux and brilliance, and even the largest detectors can collect at rates of several hundred hertz. Electron cryomicroscopy is successfully competing for structural biologists' most exciting projects. As a result, formerly scarce beam time is becoming increasingly abundant, and beamlines must innovate to attract users and ensure continued funding. Here, we will show how data collection has changed over the preceding five years and how alternative methods have emerged. We then explore how MX at synchrotrons might develop over the next five years. We predict that, despite the continued dominance of rotation crystallography, applications previously considered niche or experimental, such as serial crystallography, pink-beam crystallography, and crystallography at energies above 25 keV and below 5 keV, will rise in prominence as beamlines specialize to offer users the best value. Most of these emerging methods will require new hardware and software. With these advances, MX will more efficiently provide the high-resolution structures needed for drug development. MX will also be able to address a broader range of questions than before and contribute to a deeper understanding of biological processes in the context of integrative structural biology.

Error study and correction of Hefei Advanced Light Source

Hefei Advanced Light Source (HALS) is a future diffraction limited storage ring. The machine performance under all kinds of magnet errors is a vital component in physical design. In this paper, we present our work on the closed orbit correction, the linear beam optics compensation and the coupling control in HALS. After correction, the dynamical aperture can suffice the injection scheme.

Design and Simulation of Thin Eddy-Current Septum for Injection of Diffraction Limited Storage Ring

Design and Simulation of Thin Eddy-Current Septum for Injection of Diffraction Limited Storage Ring

Comparison of constrained optimization methods for designing a multi-bend achromat lattice

In the design of a multi-bend achromat (MBA) lattice for a diffraction-limited storage ring, there are usually many magnet parameters to be optimized and some stringent constraints to be satisfied. For example, to cancel out nonlinear dynamics effects, the phase advances between some sections are generally required to be set to certain values in the lattice design. For better designing a MBA lattice using an evolutionary algorithm, the handling of constraints will be important, because it is very hard to satisfy the constraints for most or even all of solutions in the early generations of the algorithm. This paper will first describe some methods for handling constraints, which are then applied to designing a hybrid 7BA lattice. The comparison of these methods shows that better lattice solutions can be obtained by including constraints into objective functions.

Optimization of a phase-space beam position and size monitor for low-emittance light sources.

The recently developed vertical phase-space beam position and size monitor (ps-BPM) system has proven to be able to measure the electron-source position, angle, size and divergence simultaneously in the vertical plane at a single location of a beamline. The optimization of the ps-BPM system is performed by ray-tracing simulation to maximize the instrument sensitivity and resolution. The contribution of each element is studied, including the monochromator, the K-edge filter, the detector and the source-to-detector distance. An optimized system is proposed for diffraction-limited storage rings, such as the Advanced Photon Source Upgrade project. The simulation results show that the ps-BPM system can precisely monitor the source position and angle at high speed. Precise measurements of the source size and divergence will require adequate resolution with relatively longer integration time.

The prototype of equipment protection system based on Ethernet POWERLINK for HALS

Abstract The Hefei Advanced Light Source (HALS) is brought forward to be a new diffraction limited storage ring (DLSR) light source. The technical pre-research project for the HALS is in progress. As an critical part of the project, a prototype of the equipment protection system (EPS) is developed to study the interlock protection for components of the light source. The prototype of the EPS is a distributed system based on Gigabit Ethernet POWERLINK (EPL) under EPICS architecture. A PC is used as the master managing node (MN), and 10 FPGA-based controllers is employed for the slave controlled nodes (CNs). EPL is used for the communication between the MN and CNs. This paper reports the design and results of a series of performance tests of the prototype system. The test results indicate that the prototype system can run stably with a communication cycle time 275 μ s , and the maximum global response time is about 870 μ s . This system is a feasible solution for the EPS of large-scale scientific facilities. In the further studies, the response time is expected to be further reduced by choosing high-speed photo couplers and properly arranged input signals.

Longitudinal injection scheme for an ultra-low-emittance storage ring light source with a sine wave kicker

The method of longitudinal injection to an ultra-low emittance storage ring by a sine wave kicker is investigated in this paper. Beam dynamics of the injected and stored beams are both studied. With a third-harmonic kicker, the emittance and the orbit of the stored beam can be well preserved and the injection efficiency can reach 100%.

Coherent Bragg imaging of 60 nm Au nanoparticles under electrochemical control at the NanoMAX beamline.

Nanoparticles are essential electrocatalysts in chemical production, water treatment and energy conversion, but engineering efficient and specific catalysts requires understanding complex structure-reactivity relations. Recent experiments have shown that Bragg coherent diffraction imaging might be a powerful tool in this regard. The technique provides three-dimensional lattice strain fields from which surface reactivity maps can be inferred. However, all experiments published so far have investigated particles an order of magnitude larger than those used in practical applications. Studying smaller particles quickly becomes demanding as the diffracted intensity falls. Here, in situ nanodiffraction data from 60 nm Au nanoparticles under electrochemical control collected at the hard X-ray nanoprobe beamline of MAX IV, NanoMAX, are presented. Two-dimensional image reconstructions of these particles are produced, and it is estimated that NanoMAX, which is now open for general users, has the requisites for three-dimensional imaging of particles of a size relevant for catalytic applications. This represents the first demonstration of coherent X-ray diffraction experiments performed at a diffraction-limited storage ring, and illustrates the importance of these new sources for experiments where coherence properties become crucial.

Laser-slicing at a low-emittance storage ring.

Laser-slicing at a diffraction-limited storage ring light source in the soft X-ray region is investigated with theoretical and numerical modelling. It turns out that the slicing efficiency is favoured by the ultra-low beam emittance, and that slicing can be implemented without interference to the standard multi-bunch operation. Spatial and spectral separation of the sub-picosecond radiation pulse from a hundreds of picosecond-long background is achieved by virtue of 1:1 imaging of the radiation source. The spectral separation is enhanced when the radiator is a transverse gradient undulator. The proposed configuration applied to the Elettra 2.0 six-bend achromatic lattice envisages total slicing efficiency as high as 10-7, one order of magnitude larger than the demonstrated state-of-the-art, at the expense of pulse durations as long as 0.4 ps FWHM and average laser power as high as ∼40 W.

On the advantages of operation in second-order diffraction of blazed gratings in soft X-ray monochromators.

The fact that a diffraction grating can provide twofold-smaller bandwidth when operated in second-order diffraction is long known and applied routinely in the laboratory for spectroscopy in the visible and ultraviolet spectral range. A similar routine operation in monochromators for the soft X-ray range is not reported yet. This study will thus address the feasibility of efficient diffraction of soft X-rays in the second order at reflection gratings when operated at grazing angles of incidence. The related systematic study could make profitable use of a recently introduced simple analytical equation for the prediction of the diffraction efficiency of blazed gratings with an ideal sawtooth profile. The predictions are then verified by use of rigorous calculations. The principle finding is that, by operation of gratings with lower groove densities, and thus with higher efficiencies, in higher order diffraction, one can extend the tuning in existing instruments with mechanical/optical limitations to larger photon energies. The performance in terms of transmission and spectral resolving power can be very similar to the performance of a grating with a larger groove density, which would otherwise have to be used for accessing the same energy range. This would allow operation of a single highly efficient grating over a larger photon energy interval at a modern synchrotron radiation source, e.g. from 0.3 to 2.2 keV. Without any requirement for a sophisticated grating exchange scheme, a related instrument promises to be sufficiently stable for the needs imposed by the improvements in source point stability at diffraction-limited storage rings.

Design of a hybrid ten-bend-achromat lattice for a diffraction-limited storage ring light source

Abstract The hybrid multi-bend achromat (MBA) lattice concept, proposed by ESRF EBS, has been used in some diffraction-limited storage ring (DLSR) designs due to both the lower emittance and the better nonlinear performance achieved. In this paper, to reduce the emittance for a given storage ring circumference, we extended the hybrid MBA lattice from the typical hybrid 7BA to a hybrid 10BA with three additional combined function bending magnets in the lattice center, since the emittance scales inversely with the third power of the number of bending magnets. For the hybrid 10BA lattice, two kinds of phase advances between dispersion bumps have been studied in designing a DLSR with an energy of 2.4 GeV and a circumference of 324 m. The dynamic aperture of the designed DLSR with a natural emittance of 120 ∼ 130 pm ⋅ rad is large, and the momentum aperture is also acceptable.

Stitching interferometry for synchrotron mirror metrology at National Synchrotron Light Source II (NSLS-II)

With the fast development of diffraction-limited storage rings and free electron lasers, the requirement for ultimate quality X-ray mirror is getting higher and the mirror surface needs to approach the sub-nm root mean square height specifications. These ultimate specifications challenge the X-ray mirror metrology community. In this work, we present our developed dedicated stitching metrology platform for X-ray mirror metrology. Various stitching methods with different stitching parameters are investigated in our stitching interferometric system. Some experimental results are given to demonstrate its validity and performance. According to the measurement results, the repeatability of measuring a flat mirror in the software stitching mode is at 0.1 nm RMS level. In relative angle determinable stitching mode when measuring a curved mirror with its radius of curvature varying from 50 m to 175 m, the repeatability is around 1 nm RMS.

X-ray photon correlation spectroscopy of protein dynamics at nearly diffraction-limited storage rings.

This study explores the possibility of measuring the dynamics of proteins in solution using X-ray photon correlation spectroscopy (XPCS) at nearly diffraction-limited storage rings (DLSRs). We calculate the signal-to-noise ratio (SNR) of XPCS experiments from a concentrated lysozyme solution at the length scale of the hydrodynamic radius of the protein molecule. We take into account limitations given by the critical X-ray dose and find expressions for the SNR as a function of beam size, sample-to-detector distance and photon energy. Specifically, we show that the combined increase in coherent flux and coherence lengths at the DLSR PETRA IV yields an increase in SNR of more than one order of magnitude. The resulting SNR values indicate that XPCS experiments of biological macromolecules on nanometre length scales will become feasible with the advent of a new generation of synchrotron sources. Our findings provide valuable input for the design and construction of future XPCS beamlines at DLSRs.