• G. Tosin, R. Basílio, S. Casas, R.J.F. Marcondes
  LNLS, Campinas

We present several alternative designs of hybrid bending magnets based on the use of ferrite blocks with steel pole pieces to be used in the new Brazilian storage ring - LNLS2. Their main magnetic and mechanical characteristics are presented. Such models are compared to electromagnet magnets, and some advantages and disadvantages are listed, as well as a cost estimate.

• Y. Iwashita, T. Sugimoto
  Kyoto ICR, Uji, Kyoto
• M. Masuzawa, T. Tauchi, K. Yokoya
  KEK, Ibaraki

Funding: Work partially supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (A), 18204023(2006)

Although the base line technology of the Final Focus Doublet for ILC is superconducting magnet, which is supposed to be conventional, the slender structure may be suffered from its vibration. The permanent magnets, however, do not have any vibration source in it at the steady state. The five-ring-singlet configuration, proposed by R. L. Gluckstern adds 100% strength adjustability to permanent magnet quadrupole (PMQ) lens. A prototype of this lens is fabricated and under evaluation. It was originally designed for ILC that also has the extra hole for the outgoing beam. In order to realize the beam test at ATF2, the inner bore is enlarged from D20mm to D50mm to clear the background photons from Shintake-Monitor. The magnet is described.

• M.S. Jaski, E.R. Moog, S. Sasaki
  ANL, Argonne

Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under contract number DE-AC02-06CH11357.

Investigation into a circular polarizing quasi-periodic undulator is presented here. Electromagnets are used to generate the vertical field. Permanent magnets are used to generate the horizontal field. Calculated maximum effective vertical and horizontal magnetic fields on the undulator axis higher than 8.5 kGauss are achieved at a 10.5-mm gap for a 9-cm-period undulator. Fields of this magnitude are difficult to achieve in purely electromagnetic devices. Switching the sign of the current for the vertical field electromagnets allows for right- or left-handed circular polarization. A laminated core can be introduced to allow for fast helicity switching in order to utilize lock-in detection techniques. Quasi-periodicity can be introduced in the vertical electromagnet field by reducing the current at the quasi-periodic poles and can be turned on, off, or somewhere in between. Quasi-periodicity can be introduced in the horizontal permanent magnet field by inserting weakened magnets at the quasi-periodic poles. Since it is built into the magnet structure, this quasi-periodicity cannot be turned off.

• A.B. Temnykh
  CLASSE, Ithaca, New York

Funding: Work supported by National Science Foundation under contract DMR 0225180

The paper describes the design as well as short prototype and the prototype test result of undulator magnet planned for use in Cornell Energy Recovery Linac. The prototype has pure permanent magnet (PPM) structure with 24mm period, 5mm diameter round gap and is 30cm long. In comparison with conventional undulator magnets it has: a) full X-ray polarization control; b) 40% stronger magnetic field in linear and approximately 2 times stronger in circular polarization modes; c) compactness. These advantages were achieved through a number of non-conventional approaches. Among them is control of the magnetic field strength via longitudinal motion of the magnet arrays. The moving mechanism is also used for x-ray polarization control. The compactness is achieved using a recently developed permanent magnet soldering technique for fastening PM blocks. We call this device a "Delta" undulator after the shape of it's PM blocks.

• G. Lebec, J. Chavanne
  ESRF, Grenoble
• C. Benabderrahmane
  SOLEIL, Gif-sur-Yvette

Cryogenic Permanent Magnet Undulators (CPMU) are currently being developed in some Synchrotron Light Sources. Low Temperature NdFeB Permanent Magnets are used to achieve both a high remanence and a high coercive field. Low temperature magnetization hysteresis curves cannot be obtained by a simple transformation of ambient temperature curves; this requires a specific simulation tool. A Monte-Carlo based Permanent Magnet Simulator has been developed at the ESRF. In this simulator, the magnets can be described as a set of several magnetic grains. The model inputs are physical parameters such as anisotropy constants, easy-axis distribution and coercive field. The orientation of magnetic moments are calculated for each grain according to an analytical model and optimization methods are used for fast computations. Magnetization versus external field curves is calculated in a few seconds. This fits with low temperature NdFeB magnetization measurements. These curves have been efficiently used to obtain Radia material parameters for CPMU design.

• G. Sikler, W. Gaertner, St. Sattler
  BNG, Würzburg
• A. Schöps, M. Tischer
  DESY, Hamburg

Babcock Noell GmbH manufactured for DESY 11 identical planar permanent magnet-undulators (8 for the PETRA III upgrade and 3 for FLASH). The positioning accuracy and the movement reproducibility of the two girders, defining the magnetic gap of an undulator, are of vital importance for the quality of the synchrotron light. To reach the desired performance a high quality standard was kept during the choice and procurement of the components, during the high precision machining of the parts and during the assembly phase. After the alignment, laser tracker-measurements were made and evaluated for all the 11 systems. Both, the means by which the accuracy and reproducibility were achieved, and the results of the measurements will be presented here.

• G. Lebec, J. Chavanne, C. Penel, F. Revol
  ESRF, Grenoble
• C.A. Kitegi
  SOLEIL, Gif-sur-Yvette

A cryogenically cooled in-vacuum undulator was installed in the ID6 test beamline of the ESRF in January 2008. This 2 metre long hybrid undulator has a period of 18 mm. The magnetic assembly is based on NdFeB permanent magnets cooled at a temperature close to 150 K . A liquid nitrogen closed loop is used for the cooling of the undulator. This cooling system is well adapted for achieving a uniform temperature along the magnetic assembly. An important part of the study was focused on the heat budget of the undulator under beam in the different filling modes delivered at the ESRF. The impact of the undulator on the ultra high vacuum of the ring was investigated with several warming/cooling cycles. This paper presents the main outcomes from this first experience.

• S. Prestemon, D.R. Dietderich, A. Madur, S. Marks, D. Schlueter
  LBNL, Berkeley, California

Funding: This work was supported by the Director, Office of Science, U.S. Department of Energy, under contract No. DE-AC02-05CH11231.

Superconducting undulators are currently under development at a number of light sources to serve as the next generation of insertion devices, with higher fields providing enhanced spectral range for users. Most of these devices are designed with wire-based technologies appropriate for periods greater than ~10mm. New undulator concepts yielding very short-period, high-field devices with periods of a few millimeters and a K~1 have the potential to significantly reduce the cost and enhance the performance of FEL's. Here we describe a design using high temperature superconductor tapes that are commercially available, and that promise a cost-effective fabrication process using micromachining or lithography. Detailed magnetic and spectral performance analysis will be provided.

• F. Marteau, P. Berteaud, F. Bouvet, L. Chapuis, M.-E. Couprie, J.P. Daguerre, J.-M. Filhol, A. Mary, K. Tavakoli
  SOLEIL, Gif-sur-Yvette

A new electromagnetic/permanent magnets helical undulator, with a 65 mm magnetic period is under development at SOLEIL for providing a rapid switching of the photon polarization required to perform dichroïsm experiments. The vertical field will be produced by coils fed by a fast switching power supply, with a maximum current of 350 A and a polarity switching time shorter than 100ms. The coils consist of copper sheets cut by water jet method. 26 layers of copper will be stacked together while 10 of them will be water cooled. The current-regulated power supply should be able to operate in the 4 quadrants with a 50 ppm current resolution over the full scale. The design of this home made power supply will be described. The horizontal field will be generated by NdFeB permanent magnets. The design vertical and horizontal peak field values in the helical configuration are 0.24 T at the minimum 15.5 mm gap. The magnetic design and the correction scheme will be described. A prototype was built to characterise and validate the technical choices, and the results will be discussed. The efficiency of the cooling system and the results of the magnetic measurements will be presented.

• M.K. Sullivan, K.J. Bertsche, A. Novokhatski, J. Seeman, U. Wienands
  SLAC, Menlo Park, California

Funding: Work supported by the Department of Energy under contract number DE-AC03-76SF00515.

The PEP-II B-Factory was designed and optimized to run at the Upsilon 4S resonance (10.580 GeV with a 9 GeV e^- beam and a 3.1 GeV e⁺ beam). The interaction region (IR) used permanent magnet dipoles to bring the beams into a head-on collision. The first focusing element for both beams was also a permanent magnet. The IR geometry, masking, beam orbits and beam pipe apertures were designed for 4S running. Even though PEP-II was optimized for the 4S, we successfully changed the center-of-mass energy (Ecm) down to the Upsilon 2S resonance and completed an Ecm scan from the 4S resonance up to 11.2 GeV. The luminosity throughout these changes remained near 1x10³⁴ cm^-2s^-1 . The Ecm was changed by moving the energy of the high-energy beam (HEB). The beam energy differed by more than 20% which produced significantly different running conditions for the RF system. The energy loss per turn changed 2.5 times over this range. We describe how the beam energy was changed and discuss some of the consequences for the beam orbit in the interaction region. We also describe some of the RF issues that arose and how we solved them as the high-current HEB energy changed.

• G.H. Gillespie, W. Hill
  G.H. Gillespie Associates, Inc., Del Mar, California
• J.F. DeFord, B. Held
  STAAR/AWR Corporation, Mequon

Funding: Work at G. H. Gillespie Associates, Inc. funded by the U.S. Department of Energy SBIR grant number DE-FG02-05ER84360

An automated procedure for the calculation of particle transfer maps using computed magnetic field data has been developed for several types of magnetic quadrupoles. The Automated Transfer Map Generator (ATMG) software used for these calculations combines the Analyst program and specialized modules of the Particle Beam Optics Laboratory (PBO Lab). Analyst's scripted solids capability is used to develop models of different magnet concepts. The geometry and material attributes for a given magnet concept are encapsulated by a small number of magnet parameters. Quadrupoles of the same basic concept can be simulated by using different values for the magnet parameters. The three-dimensional magnetic field solver (MS3p) of the Analyst program is used to obtain the fields. New PBO Lab modules are used to automate the field computation, and then calculate the transfer maps and matrices through third-order using the Venturini-Dragt method. Examples for three different types of magnetic quadrupole lenses are presented: electromagnetic air-core, electromagnetic iron-core, and rare-earth permanent magnet quadrupoles.