Superconducting Wavelength Shifter Research Articles

Design and Fabrication of NbTi Coils for a Superconducting Wavelength Shifter

Design and Fabrication of NbTi Coils for a Superconducting Wavelength Shifter

Beam loss study and its application to the Taiwan Light Source and Taiwan Photon Source

The mechanism of beam loss and radiation hot spots at the Taiwan Light Source (TLS) and Taiwan Photon Source (TPS) are studied using various types of beam loss monitors (BLMs). The performance of readout devices and the system integration are also presented in this paper. At the TLS, the high beam loss spots downstream of the superconducting wigglers comes from the vertical aperture limit. The highest radiation is detected after the injection section and comes mainly from X-rays generated by the superconducting wavelength shifter installed between the 3rd and 4th kickers. At the Taiwan Photon Source, the high radiation spots are located before the second bending magnet and straight section because there are photon absorbers nearby to contain synchrotron radiation. In order to enhance the sensitivity to beam loss, 1-mm thick lead is used to shield synchrotron radiation to the BLM. The beam loss coming from scattering occurs downstream of the following bending magnet in a poor vacuum region for inelastic scattering and after vertical aperture limitation for elastic scattering. During routine operation in which the beam loss mainly comes from intra beam scattering during decay period, the beam loss pattern varies with the gap and phase of the insertion devices especially for the narrowest gaps. These BLMs are used to adjust skew-quads or sextupoles to minimize the beam loss for maximum beam lifetime. The precise beam energy of the TPS is also calibrated using spin-depolarization in which the beam losses are detected by scintillation detectors. The energy stability during continuous routine operation can be kept to within 10−5 by radio frequency adjustments and fast orbit feedback.

Grazing Incidence X-Ray Diffraction using Synchrotron Light at SLRI

This work demonstrates the capability of the grazing incidence X-ray diffraction technique using synchrotron light. The measurement system is set up at the BL7.2W:MX beamline of the Synchrotron Light Research Institute (SLRI). The beamline utilizes hard X-rays from a 6.5-Tesla Superconducting Wavelength Shifter. The photon energy can be chosen between 7 to 18 keV with a photon flux of more than 1010 photons/sec at 100mA stored electron beam. The X-ray beam size can be reduced down to 20 microns, allowing XRD measurements in grazing geometry, thus crystal structures of very thin films with a thickness of tens nanometers can be identified. The diffraction patterns are recorded with a 2D CCD detector, allowing more diffraction spots of single crystalline films to be recorded.

Design and Performance of Power Supplies for Superconductor Insertion Devices at TLS 1.5-GeV Ring

A sophisticated power supply system was developed, installed, and successfully put into operation for the superconducting insertion devices at the 1.5-GeV Taiwan Light Source. These magnets include a superconducting wavelength shifter, a superconducting multipole wiggler, and three in-achromate superconducting wigglers. The power supply, with ±350-A/±15-V output power, is a four-quadrant bipolar switching step-down converter. The power supply, employing multiple regulation loops, slew rate control, and ultra high precision current transducer for feedback loop, is capable of delivering highly stable and reliable current to the superconducting loads. The topology, control scheme, and its performance are described in this paper. The power supply system's performance and reliability will be further improved and adopted to power low-temperature superconducting devices at the National Synchrotron Radiation Research Center in the future.

Indus-2 Synchrotron Radiation Source: current status and utilization

Indus Synchrotron Radiation complex at Raja Ramanna Centre for Advanced Technology at Indore, India houses two synchrotron radiation sources: Indus-1 and Indus-2. Indus-1 is a 450 MeV source emitting in VUV/ soft x-ray region and operating at 100 mA since 1999. Indus-2 is designed for 2.5 GeV, 300 mA operation and is operating at 2 GeV and 100 mA since March 2010 in 24x7 mode and a beam lifetime of about 22 hrs has been achieved. Operation at 2.5 GeV and 100 mA has recently been demonstrated with the addition of in-house developed solid state RF amplifiers. Indus-2 can accommodate 21 bending magnet (BM) and 5 insertion device (ID) beamlines. Sixteen BM beamlines have been planned and six BM beamlines namely i) Angle Dispersive XRD ii) Energy dispersive XRD iii) Energy dispersive EXAFS iv) Soft and deep x-ray lithography v) X-ray fluorescence micro-probe and vi) X-ray photoelectron spectroscopy beamlines have been commissioned. These are being used by researchers from different universities, national institutes and laboratories for carrying out several investigations. Two more beamlines namely 'Grazing incidence x-ray scattering' and 'Protein crystallography' are nearing commissioning. A number of materials research related problems have been investigated using these beamlines and several papers have already been published. Here we will report on the current status of the source, details of the beamlines already operational, beamlines to be commissioned soon and several up-gradation schemes that are being planned. Five IDs consisting of two soft x-ray planar undulators, one superconducting wavelength shifter / wiggler, one APPLE II soft x-ray helical undulator and one hard x-ray undulator will be installed during the next few years. Three new ID based beamli-nes for Atomic and Molecular physics, Angle integrated / Angle resolved PES and Magnetic Circular Dichroism experiments will be commissioned.

Effect of wavelength shifter on Indus-1

The Indus-1 is a 450 MeV synchrotron radiation source for the production of VUV radiation ( λ c=61 Å). In order to produce the radiation of shorter wavelength ( λ c=31 Å), a superconducting wavelength shifter (WLS) with a peak field of 3 T is being considered for Indus-1. In the Indus-1 beam lifetime is short; therefore, WLS will be kept on during beam injection. To predict WLS effect, Smith's Hamiltonian for Halbach's magnetic field model has been re-derived to estimate linear and nonlinear component under the compensated electron beam trajectory transformation. To minimize the linear effects of WLS, various linear compensation schemes and its effects on Indus-1 operation are presented.

A 6.4 T superconducting wavelength shifter for the generation of hard X-rays at the Siam Photon Source

The Siam Photon Source plans to provide hard X-rays to synchrotron radiation users specifically those in the fields of macromolecular crystallography and X-ray absorption fine-structure spectroscopy. In order to generate synchrotron radiation in the hard X-ray spectral range from a low-energy (1.2 GeV) electron storage ring, installation of a high-field superconducting insertion device is necessary. A warm-bore superconducting magnet wavelength shifter, which was given to NSRC by MAX-LAB, Sweden, will be inserted into the storage ring in the middle of a straight section. The magnet consists of three pairs of iron-cored superconducting NbTi coils with a nominal peak field of 6.4 T. This report will discuss the characteristics of the WLS, the beam dynamics effects of the wiggler on the SPS storage ring optics and the necessary compensations, as well as radiation properties and radiation masking.

A superconducting wavelength shifter as primary radiometric source standard in the X-ray range

For more than 20 years, the Physikalisch-Technische Bundesanstalt (PTB) has been using the calculable radiation of bending magnets from the BESSY I and BESSY II electron storage rings in the visible, UV, vacuum-UV (VUV) and X-ray spectral range for radiometry, especially for the calibration of radiation sources and energy-dispersive detectors. Due to its—compared to bending magnets—higher magnetic field, wavelength shifters (WLS) have the potential to extend the usable spectral range for these applications to higher photon energies. Thus, the characteristic energies of BESSY II bending magnet radiation and a 6 T WLS radiation are 2.5 and 11.5 keV, respectively. Within the scope of this work, the properties of the synchrotron radiation from the 6 T WLS have been investigated and compared to theoretical predictions for photon energies up to 150 keV. Good agreement within the experimental uncertainty of several percent was found. Further improvements for a future radiometric use of WLS radiation with low uncertainties will be discussed.

X-ray beamlines for structural studies at the NSRRC superconducting wavelength shifter

Using a superconducting-wavelength-shifter X-ray source with a photon flux density of 10(11)-10(13) photons s(-1) mrad(-1) (0.1% bandwidth)(-1) (200 mA)(-1) in the energy range 5-35 keV, three hard X-ray beamlines, BL01A, BL01B and BL01C, have been designed and constructed at the 1.5 GeV storage ring of the National Synchrotron Radiation Research Center (NSRRC). These have been designed for structure-related research using X-ray imaging, absorption, scattering and diffraction. The branch beamline BL01A, which has an unmonochromatized beam, is suitable for phase-contrast X-ray imaging with a spatial resolution of 1 microm and an imaging efficiency of one frame per 10 ms. The main beamline BL01B has 1:1 beam focusing and a medium energy resolution of approximately 10(-3). It has been designed for small-angle X-ray scattering and transmission X-ray microscopy, used, respectively, in anomalous scattering and nanophase-contrast imaging with 30 nm spatial resolution. Finally, the branch beamline BL01C, which features collimating and focusing mirrors and a double-crystal monochromator for a high energy resolution of approximately 10(-4), has been designed for X-ray absorption spectroscopy and high-resolution powder X-ray diffraction. These instruments, providing complementary tools for studying multiphase structures, have opened up a new research trend of integrated structural study at the NSRRC, especially in biology and materials. Examples illustrating the performances of the beamlines and the instruments installed are presented.

Design, Construction, and Performance Testing of a 6.5 T Superconducting Wavelength Shifter

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A compact three-pole superconducting magnet with an aluminum warm beam duct was designed and fabricated as an X-ray source in a 1.5 GeV Taiwan Light Source (TLS) or the 3 GeV Taiwan Photon Source (TPS). Three pairs of racetrack NbTi superconducting coils were connected to one main power supply to create a central field of over 6.5 T. Two low current trim power supplies were connected in parallel to the two side pairs of the coil to eliminate the first and second field integrals. The wavelength shifter magnet was cooled in a pool boiling helium bath. Helium boils off at 1.3 L/hr. The vapor-cooled current lead is used to pass the 350 A excitation current. The magnetic field strength was measured at room temperature using a Hall probe and a stretched wire system. The magnet was tested successfully to 308 A, at which the central field exceeded 6.5 T, and the peak field on coil was 8.2 T. The design and construction of the magnet and the cryostat, the quenching protection, and field measurement results will be presented and discussed. </para>

X-Rays at the SIAM Photon Source

In this note, we describe the upgrade effort to convert the SIAM Photon source into an Xray synchrotron radiation facility with photon energies up to some 15 keV. This conversion of SIAM Photon into a third generation light source can be achieved through an increase of the electron beam energy and the addition of recently available superconducting wavelength shifter and multipole wiggler magnets. A gradual retrofit of vacuum chambers aiming at a reduction of electron beam instabilities as well as a modification of the focusing structure are expected to greatly increase the brightness of the photon beam. These upgrades will be implemented gradually over a few years to minimize the interruption of ongoing experimental activities. As an ultimate upgrade, a study has been started which shows the feasibility to implement a 2 GeV storage ring replacing the present ring in the same foot print. This new ring is configured to provide double the number of insertion device photon beam lines.

A new small angle X-ray scattering station at NSRRC

Using the X-ray source generated by a newly installed superconducting wavelength shifter at the Taiwan Light Source storage ring of the National Synchrotron Radiation Research Center (NSRRC), we have constructed an X-ray beamline equipped with a small angle X-ray scattering (SAXS) station for nanostructure research. This beamline can deliver a photon flux of ∼3×1011photons/s in the energy range of 5–22keV, with a beam divergence of ∼0.3mrad in vertical direction. With the new SAXS end station we have studied PtRu nanoparticles embedded in fine carbon grains using anomalous SAXS. We illustrate other features of the SAXS instrument with a few more measurements on phase transitions of diblock-polymers, structural evolution of aluminium alloys under an artificial aging at high temperature, and folding and unfolding of lysozyme in aqueous solutions.

Installation and Commissioning of a 6-Tesla Superconducting Wavelength Shifter at Taiwan Light Source

The Taiwan Light Source (TLS) is the first third-generation light source in Asia. The storage ring has six straight sections one section for injection, one for the RF cavities and diagnostic instrumentation and four sections for insertion devices, which are U5, U9, EPU and W20. Generating high-energy X-ray photons is a high priority at TLS. A single hybrid type wiggler is associated with three beam lines to serve X-ray users. The installed Superconducting Wavelength Shifter (SWLS) is very compact in size and can produce very high-energy photons. The injection section at TLS can barely accommodate the SWLS. The expected multipole components of the SWLS are strong, shrink the dynamic aperture; perturb the beta function, and reduce the beam lifetime. The increase in the synchrotron radiation by the SWLS also changes beam emittance and increases the energy spread. The influence of SWLS on the low-energy, 1.5 GeV, storage-ring should not be neglected. The downstream kicker with the water-cooled copper mask must be modified to prevent a potential meltdown of the welding junction of the ceramic chamber because the heat load is high. The 1.2 μs half-sine pulse field of the kicker is then altered by the copper-made radiation mask, which is installed inside the ceramic chamber. The operating capability of cryogenic system is established to ensure the smooth commissioning of the SWLS. The magnetic field mapping, the dynamic aperture simulation data and commissioning results will be presented and discussed herein.

Commissioning of a 6.4T superconducting wavelength shifter at MAX-lab

The 6.4 T wavelength shifter at MAX-lab is a three pole superconducting planar wiggler with a warm bore, i.e. the vacuum tube passing through the wavelength shifter is at ambient temperature. The wavelength shifter, including surrounding systems such as power supply and He liquifier, has been assembled, tested, and commissioned at MAX-lab. The wavelength shifter has been installed into the 1.5 GeV MAX II electron storage ring. A field of 6.4 T in the central pole has been obtained and a consumption of 4.3 l/h of liquid helium has been measured under nominal working conditions. The influence on the stored electron beam in the MAX II ring has been measured and the measurements have shown that the wavelength shifter will not degrade the performance of MAX II. The wavelength shifter is however not in use at present and it has been taken out of the MAX II storage ring.

Mechanical structure analysis of a compact superconducting wavelength shifter

A three-pole superconducting wavelength shifter (SWLS) cooled by a 1.5 W @ 4.2 K Gifford-McMahon cryocooler will be installed in SRRC's storage ring in the year 2002 to provide the synchrotron radiation light source with critical energy at 9 keV. This article shows the mechanical structure design of the cryogen-free SWLS. The three pairs of coils are supported in an aluminum-reinforced block and bonded by two iron return yokes. The poles are fixed to the return yoke and will move with the yoke. The finite element method is used to evaluate the stresses caused from the thermal contraction of materials and the coil's Lorentz force. The simulation result shows that the thermal stress of coil from 293 K to 4.2 K is too large and will cause the failure of the coil if the poles, the coils, and the aluminum support are all fixed together. The stress level is not reduced even the soft material is placed among the interfaces of these different parts. The reduction of the stress level is achieved by leaving a suitable clearance among these interfaces and allowing relative sliding motion between the return yoke and the coil, and between the coil and the aluminum support. Analysis results show that such a design will reduce the stress to a level of two to three times less.

Design and construction performance of a compact cryogen-free superconducting wavelength shifter

A compact cryogen-free superconducting wavelength shifter with a warm bore for electron beam has been constructed for generating synchrotron radiation hard X-rays. This magnet consists of three pairs of racetrack NbTi superconducting coils that can produce a maximum magnetic field of 6.0 Tesla at the central pole. The superconducting coils, the aluminum supporting block, and the return iron yokes are cooled to 4 K, and the thermal shielding and HTS current leads to 60 K, by using a 1.5 W Gifford-McMahon type cryocooler. The technical issues on the magnet design and the construction process are presented. Several different measurement systems are used to characterize the magnetic field performance.

An overview of the insertion device development at SRRC

Five high performance insertion devices, namely W20, U10, U5, U9 and EPU5.6, have been constructed and installed in the storage ring of the Synchrotron Radiation Research Center (SRRC). Among them, the 2-m-long conventional undulator U10 and the 4-m-long elliptically polarized undulator EPU5.6 were designed and built in-house. These two devices have achieved high magnetic field quality and high spectral performance. To facilitate hard-X-ray experiments, the project of building a superconducting wavelength shifter (SWLS) and a superconducting multi-pole wiggler (SMPW) is ongoing. These two superconducting insertion devices were designed to be cryogen-free.

Monochromators for High-Energy Synchrotron Radiation

Several monochromators, which are based on the use of cylindrically bent perfect Si crystals, have been constructed at the High Energy X-ray Scattering beamlines of the ESRF. The monochromators provide different focusing conditions, and the energy band-passes are optimized for the needs of different experiments. Formulas are given for calculation of the focal distances, reflectivity curves, and energy distributions. The lay-out of the beamlines follows the Troika concept, where the radiation fan is either split in 3 beams, or the central beam is utilized successively by semi-transparent monochromators to serve three experimental stations simultaneously. The radiation sources are a 7-period permanent magnet asymmetric wiggler and a superconducting wavelength shifter. The critical energies are 45 keV and 96 keV, respectively. The lowest operation energy is 30 keV, and transmission type monochromators have been used up to 1 MeV photon energies. Typical X-ray flux at the sample is 10

The design of a compact cryogen-free superconducting wavelength shifter for synchrotron radiation

A compact three-pole superconducting magnet with a warm bore for electron orbit has been designed to serve as a wavelength shifter for Taiwan synchrotron radiation light sources. The wavelength shifter will have a warm beam duct, which is 600 mm in length, 100 mm in width and 20 mm in high. Three pairs of racetrack superconducting coils were designed to create a central field and to adjust the integral field close to zero. A maximum magnetic field of 6.5 Tesla at the central pole will be generated. To avoid induced currents, all six coils are connected electrically in series and powered by a high current power supply. Two low current trim power supplies are used to adjust currents on the two side pairs of coils in order to eliminate the first and the second magnetic field integrals. The shape of pole pieces and superconducting coils are specially designed to minimize the higher harmonic terms of the magnetic field, especially the sextupole field component. Both the superconducting coils and the iron yokes are cooled by a single 1.5 W Gifford-McMahon cryo-cooler. The normal operation of the 6.5 T wavelength shifter will be cryogen free.

Scanning X-ray spectrometer for high-resolution Compton profile measurements at ESRF

A scanning-type crystal spectrometer for high-resolution Compton profile measurements has been constructed at the High Energy Inelastic Scattering Beamline (ID15B) of the ESRF. Radiation from a seven-period asymmetrical permanent-magnet wiggler or from a superconducting wavelength shifter is focused horizontally onto the sample by a bent-crystal monochromator. Typical energies are 30, 50 and 60 keV, the flux on the sample is 1012 photons s−1, and the relative energy bandwidth is 3 × 10−4. The spectrometer operates in the Rowland circle geometry, where the sample is fixed and the cylindrically bent analyser crystal and the detector move on the focusing circle by synchronized translations and rotations. The main detector is a large-diameter NaI scintillation counter, the incident beam is monitored by an Si diode, and scattering from the sample is detected using a Ge detector. The recorded spectrum is corrected for the energy-dependent response of the spectrometer, background and multiple scattering, and converted to the momentum scale. The resolution of the spectrometer is calculated from the geometrical factors and the reflectivity curve of the analyser crystal, and the result is checked against the widths of the elastically scattered line and fluorescent lines. So far, 0.1 a.u. resolution in electron momentum has been achieved. The typical average count rate over the Compton profile is about 1000 counts s−1 from a weakly absorbing sample.