NSRRC, Hsinchu
An in-vacuum undulator with a room-temperature permanent magnet and a superconducting wiggler has become a mature technology and is widely used; it can adopt a short-period length in a medium-energy facility to provide an enhanced photon flux in the hard x-ray region. A cryogenic permanent magnet is applicable for an in-vacuum undulator to enhance the remanence field (Br) and the coercivity force. In future, a cryogenic permanent-magnet undulator and a superconducting wiggler will become mainstream to fulfill a user's requirement of a discrete and a continuous spectrum, respectively, but superconducting technology with HTS wires will have the best potential for the development of insertion devices after the next decade. HTS bulk magnets with magnet flux density 17 T are applicable even for a superconducting undulator; such an undulator can decrease the period length to about 10 mm. A small magnet gap with an extremely- short-period length (about 5 mm) has been studied with a stacked-layer of thin HTS tapes for a superconducting undulator. This report is a review to describe the current and future developments of insertion devices for a medium-energy storage ring and FEL facility.
KEK, Ibaraki
KEK is studying the design of the interaction region quadrupoles for the SuperKEKB of which the two beams of 4GeV/7GeV for LER/HER have a crossing angle of 83 mrad. For each beam, the final beam focusing system consisting of superconducting and permanent magnets is studied. The superconducting quadrupoles close to the interaction point for each beam are located in the compensation superconducting solenoid which cancels the solenoid field by the particle detector, Belle. These magnet parameters are optimized to obtain higher luminosity. In this paper, the design progress of final focusing system and magnets will be reported.
Kyoto ICR, Uji, Kyoto
ILL, Grenoble
RID, Delft
ANL, Argonne
KURRI, Osaka
RIKEN, Wako, Saitama
ANSTO, Menai
KEK, Ibaraki
We have developed a motorized magnetic lens for focusing of pulsed white neutron beams. The lens is composed of two concentric permanent magnet arrays, in sextupole geometry, with bore of 15 mm and magnet length of 66 mm. The inner magnet array is stationary, while the outer array is rotated (the frequency of the modulation of magnetic field inside the bore ν ≤ 25Hz), providing a sextupole magnetic field gradient range of 1.5x104T/m2 ≤ g' ≤ 5.9x104T/m2. By synchronization of a pulsed neutron beam with the sinusoidal modulation of the magnetic field in the lens, the beam is focused, without significant chromatic aberration, over a wide neutron wavelength band. We have constructed a focusing-SANS (Small Angle Neutron Scattering) test bed on the PF2-VCN (Very Cold Neutron) beam line at the Institut Laue-Langevin in Grenoble. The beam image size matched the source size (≈ 3mm) over of wavelength range of 30Å ≤ λ ≤ 48Å with focal length of ~ 2.3 m. Further, we have demonstrated the performance of this device for high resolution time-of-flight (tof) SANS for a selection of polymeric & biological samples, in a compact geometry of just 5 m.
SLAC, Menlo Park, California
CERN, Geneva
University of Pisa and INFN, Pisa
INFN/LNF, Frascati (Roma)
BINP SB RAS, Novosibirsk
A final focus magnet design that uses super-ferric magnets is introduced for the Super-B interaction region. The baseline design has air-core super-conducting quadrupoles. This idea instead uses super-conducting wire in an iron yoke. The iron is in the shape of a Panofsky quadrupole and this allows for two quadrupoles to be side-by-side with no intervening iron as long as the gradients of the two quads are equal. This feature allows us to move in as close as possible to the collision point and minimize the beta functions in the interaction region. The super-ferric design has advantages as well as drawbacks and we will discuss these in the paper.
JASRI/SPring-8, Hyogo-ken
RIKEN/SPring-8, Hyogo
A beam halo region of an electron beam at a linear accelerator might hit the undulator magnets and degrade undulator permanent magnets. An interlock sensor is indispensable to protect the magnets against radiation damage. We have been developing an electron beam halo monitor using diamond detectors for an interlock sensor at the X-ray free electron laser facility at SPring-8 (XFEL/SPring-8). The diamond detectors are operated in photoconductive mode. Pulse-by-pulse measurements are adopted to suppress the background noise efficiently. The feasibility tests of this monitor have been performed at the SPring-8 compact SASE source (SCSS) test accelerator for XFEL/SPring-8, and the results will be summarized.
LNLS, Campinas
"Green solutions" using permanent magnets are being proposed for the dipoles and quadrupoles of the second Brazilian Synchrotron Light Source - LNLS2 - magnetic lattice. The main purpose is to reduce as much as possible the electrical energy consumption, assuring the reliability of the magnets during several years. Sextupoles will have multiple functions due to the limited space in the lattice design.
SOLEIL, Gif-sur-Yvette
The production of hard X rays at SOLEIL, a 2.75 GeV, requires short period and small gap in-vacuum undulators. For shifting further the radiation toward higher energies, the peak magnetic field of the undulators can be further increased by cooling the permanent magnets at cryogenic temperature below 100 K. A R&D programme for the construction of a 2 m long 18 mm period CPMU is launched: the use of PrFeB enables to increase the peak magnetic field at a cryogenic temperature of 77 K. Praseodymium was chosen instead of Neodymium type magnets, because it prevents the appearance of the Spin Reorientation Transition. The magnetic characterisation of different permanent magnet grades at cryogenic temperatures (NdFeB and PrFeB), and the magnetic and thermal measurements on a small 4 period NdFeB cryogenic undulator are presented. The status on the progress of the CPMU conception is given. The magnetic and mechanical design, including the cooling of the girders at 77K, and the thermal budget are described. The designs of the dedicated magnetic measurement benches, which will be required to check the magnetic performance of the undulator at low temperature, are also reported.
ESRF, Grenoble
An important upgrade of the ESRF is planned from 2009 to 2016. It is mainly driven by the improvement of beamlines performances and capacity. On the storage ring side, the length of the straight sections will be increased from 5 m to 6 m with a possible further extension to 7 m. These long sections will provide a higher photon flux, and it will allow the installation of canted undulators. The length of the insertion devices (ID), such as revolver undulators and in-vacuum undulators, will be modified to fit the first upgraded beamline sections. The resulting implication on the length of new IDs will be presented. The concept of canted undulators is a proposed optional feature. It will rely on novel permanent magnet chicane providing a maximal separation angle of 5.4 mrad while keeping short distance between canted undulators. Magnetic chicane magnets with low fringe field and homogeneous longitudinal field integral have been designed. The developed magnets will be presented.
BNG, Würzburg
Karlsruhe Institute of Technology (KIT), Karlsruhe
Superconducting insertion devices (IDs) are very attractive for synchrotron light sources since they allow increasing the flux and/or the photon energy with respect to permanent magnet IDs. Babcock Noell GmbH (BNG) completed the fabrication of a 1.5 m long unit for ANKA at KIT. The period length of the device is 15 mm for a total of 100.5 full periods plus an additional matching period at each end. The key specifications of the system are: a K value higher than 2 for a magnetic gap of 5 mm, the capability of withstanding a 4 W beam heat load and a phase error smaller than 3.5 degrees. The field performance of the magnets has been qualified with liquid helium in a vertical dewar. As a result of this test the local correction coils have been installed and the magnets inserted in the final cryostat. During the factory acceptance test, the conduction cooling operation has been qualified and at the moment the undulator is ready to be tested at KIT. This paper describes the main features of the system and the results of the factory acceptance tests.
RIKEN/SPring-8, Hyogo
PSI, Villigen
JASRI/SPring-8, Hyogo-ken
The cryogenic permanent magnet undulator (CPMU) is an insertion device in which permanent magnets are cooled down to cryogenic temperature (CT) to improve the magnetic performances. Although CPMUs are realized by a slight modification of in-vacuum undulators (IVUs), we have several technical challenges to be overcome. Among them, the most important one is how to ensure the magnetic performance, in other words, how to measure the magnetic field at CT, and how to correct it if necessary. A new method of the phase-error correction has been proposed at SPring-8, in which the gap variation is corrected by adjusting mechanically the in-vacuum beam. What is important in this method is that the correction can be done at CT without breaking the vacuum, i.e., an 'in-situ' field correction is possible. The correction method has been tested to check the feasibility using the new CPMU with a magnetic period of 14 mm and a magnetic length of 1.7 m constructed for Swiss Light Source. In this paper, the principle and results are described together with the details of the new measurement system SAFALI (self aligned field analyzer with laser instrumentation) for the field measurement of CPMUs.
ISIR, Osaka
KEK, Ibaraki
The edge-focusing (EF) wiggler has been fabricated to evaluate its performance rigorously with the magnetic field measurement. It is a 5-period planar wiggler with an edge angle of 2° and a period length of 60 mm. The magnetic field is measured using Hall probes at four different wiggler gaps. It is experimentally confirmed that a high field gradient of 1.0 T/m is realized, as designed, along the beam axis. The magnetic field gradient of the EF wiggler is derived as a function of the magnetic gap. The field gradient decreases with increasing magnet gap more slowly than the peak magnetic field does for the present experimental model. An analytic formula for the field gradient of the EF wiggler is derived and it is shown that the slope of the field gradient with the magnet gap can be changed by varying the magnet width of the EF wiggler. We analyzed the relation between the orientation errors of the measurement system and the measured magnetic field or field gradient using a model magnetic field of the EF wiggle. We corrected the measurement magnetic field based on this analysis and evaluated the performance of the EF wiggler.
USTC/NSRL, Hefei, Anhui
The enhancement of arbitrary odd harmonic field is analyzed for pure permanent magnet undulator. The two dimensional analytical formula of the magnetic field is given for a modified Harbch type undulator, in which the magnet blocks have different size. It is shown that the odd harmonic field can be enhanced by optimal the length ratio of the vertical magnetized magnet blocks and the horizontal magnetized magnet blocks, the 3rd harmonic field can exceeded 20% of the fundamental field and 7th harmonic field can exceeded 3 % of the fundamental field for magnet gap-period ratio equal to 0.1.
NSRRC, Hsinchu
Shimming magnetic field error on each pole in the Elliptically Polarized Undulator (EPU) is a time-consuming work and highly based on experience without scientific systematic methods. Therefore, an auto-field shimming program is developed to save time on pole shimming process. The program is including two major steps to analyze where the poles is defective or imperfect. Step one is to clarify the magnetic pole quality. If its quality is far away to user-defined standards, we change the pole instead of processing to balance them relatively for uniform magnetic field. The magnetic pole quality is based on deltaB/Bavg and deltaI/Iavg(half period of integral) percentage. The second step is to build the effective field and once integral model of pole and permanent magnet calculation. If we shim the defective pole by moving vertically and transversely, it would surge intrinsic change of the deltaB/Bavg and deltaI/Iavg at defective and surrounded poles. Auto-field shimming algorithm would assist us to plan shimming strategies to deal with magnetic poles.
KEK, Ibaraki
J-PARC, KEK & JAEA, Ibaraki-ken
The power supply current ripple of the quadrupole magnets of the J-PARC main ring has been measured to be the order of 10-4. The magnetic field of the quadrupole magnets has been measured and the ripple frequency distribution of each magnet was observed to be depending on where the magnet is in the magnet chain. A transmission line model for the cable and magnets was able to explain the distribution. The field ripple made by the common mode current ripple was reduced by changing the magnet cabling to be symmetrical with respect to the N and S poles of the quadrupole magnets. The common mode ripple was drastically reduced. The normal mode ripple of 600, 1200 and 1800 Hz however remained. The field ripple was further reduced using resistors those are connected in parallel to the magnet coils and bypass the current ripple. It was effective to the higher frequency ripple of 1200 and 1800 Hz and the effect was in a good agreement with an electric circuit simulation program LTspice.
Kyoto ICR, Uji, Kyoto
KEK, Ibaraki
A prototype of a permanent magnet quadrupole lens for ILC final focus doublet is fabricated. In order to demonstrate the feasibility, it will be tested in a real beam line. Such practical experiences include its shipping, storage, handling, installation, alignment technique, and so on. Because permanent magnets cannot be switched off in contradistinction to electromagnets, they should be evacuated from beam lines when no interference is desired and the process should be quick with enough reproducibility. The magnetic center and strength stability including reproducibility are also important issues during the beam test. In order to reduce interferences with current ongoing testing items at ATF2, the magnet will be installed at a further upstream position of the ATF2 beam line. The installation and test plan will be described.
UCLA, Los Angeles, California
RadiaBeam, Marina del Rey
One of the challenges of the proposed muon collider is the beam size at the interaction region. The current target for the beta function (beta-star) is 10mm for the 1.5TeV scenario with a beam emittance of 25mm-mrad. In this paper, we describe the design and development of a final focusing scheme that attempts to reach these parameters. The final focus scheme is based on the use of permanent magnet quadrupoles (PMQ) in a triplet configuration. Initial simulations show that the PMQs reach gradients as high as ~990T/m using Praseodymium based magnets in a Halbach style arrangement. Possible methods for tuning the PMQs at the interaction region, via temperature control and high-resolution movers, are also described.