IPAC2011 - List of Keywords (permanent-magnet)

Paper	Title	Other Keywords	Page
TUODA02	Status of Sirius – a New Brazilian Synchrotron Light Source	dipole, emittance, lattice, synchrotron	931
	L. Liu, R. Basílio, J.F. Citadini, R.H.A. Farias, R.J.F. Marcondes, X.R. Resende, F. Rodrigues, A.R.D. Rodrigues, P.P. Sanchez, R.M. Seraphim, G. Tosin, F. H. de Sá LNLS, Campinas, Brazil
	We present an overview of the new synchrotron light source project Sirius, currently being designed at the Brazilian Synchrotron Light Laboratory (LNLS) in Campinas, São Paulo. Sirius will consist of a 480 m circumference, 3.0 GeV, 20 TBA cells, 1.7 nm.rad emittance storage ring. The dipoles will be based on the use of permanent magnet technology and will combine low field magnets (0.5 T) for the main beam deflection with a short slice of high field magnet (2.0 T) to generate photons of 12 keV critical energy with modest total energy loss. There will be 18 straight sections for insertion devices. In this report we describe the current status for the magnet lattice design and some of the subsystems.
	Slides TUODA02 [2.434 MB]

TUODB03	Innovative Design of the Fast Switching Power Supplies for the SOLEIL EMPHU Insertion and its Fast Correctors	power-supply, controls, undulator, simulation	982
	F. Bouvet, D. Aballea, R. Ben El Fekih, S. Bobault, M. Bol, Y. Bouanani, Y. Dietrich, A. Hardy, F. Marteau SOLEIL, Gif-sur-Yvette, France
	A new electromagnetic/permanent magnets helical undulator has been designed and is under commissioning at SOLEIL. For a fast switching of the photon polarization, it requires a power supply able to switch between +/350 A within 50 ms, without any current overshoot and with a very good current resolution over the full scale (50 ppm). The in-house design is based on two full switching bridges with interleaved commands. Combined with a regulation scheme using sophisticated algorithms, such a design enables to reach a high control bandwidth, permitting fast transitions. Such a fast and accurate system needs well performing digital control electronics. We chose the digital control cards developed at Paul Scherrer Institute (Villigen CH) for the SLS (Swiss Light Source). The components, measurements, interlocks, control interfaces, and electronic cards were developed and assembled together at SOLEIL. This paper will present the main lines of this development and the performances achieved during the EMPHU insertion commissioning. The design of the fast power supplies (±20 A) needed for corrector magnets of this insertion will also be presented.
	Slides TUODB03 [3.017 MB]

TUPS087	Development of Permanent Magnet Focusing for Klystrons	klystron, cathode, focusing, target	1743
	Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan S. Fukuda, T. Matsumoto, S. Michizono, M. Yoshida KEK, Ibaraki, Japan
	Funding: KEK Applying permanent magnet technology to beam focusing in klystrons can reduce their power consumption and reliability. These features benefit variety of applications especially for large facilities that use number of klystrons such as ILC. A half scaled model will be available in summer and full model should be available in September. Research and Development status will be reported.

WEOBA03	Non-scaling Fixed Field Alternating Gradient Permanent Magnet Cancer Therapy Accelerator	acceleration, proton, cavity, lattice	1923
	D. Trbojevic BNL, Upton, Long Island, New York, USA V.S. Morozov JLAB, Newport News, Virginia, USA
	Funding: Work performed under U.S. DOE Contract Number DE-AC02-98CH10886. We present a design of the proton therapy accelerator from 31 MeV to 250 MeV by using racetrack lattice made of Non-Scaling Fixed Field Alternating Gradient (NS-FFAG) arcs and two parallel straight sections. The magnets in the arcs are separated function Halbach type magnets. The dipole bending field is 2.3 T, while the Neodymium Iron Boron magnetic residual induction is Br=1.3 T. The radial orbit offsets in the NS-FFAG arcs, for the kinetic energy range between 31 MeV < Ek < 250 MeV or momentum offset range -50% < δp/p < 50%, are -11.6 mm < x max < 16.8 mm, correspondingly. The straight sections used for the cavities and single turn injection/extraction kickers and septa are with zero orbit offsets. The permanent magnets accelerator should reduce overall and operating cost. It could fit into 8 x 12 m space.
	Slides WEOBA03 [2.789 MB]

WEPO017	Status of CLIC Magnets Studies	quadrupole, linac, solenoid, acceleration	2433
	M. Modena CERN, Geneva, Switzerland A.S. Vorozhtsov JINR, Dubna, Moscow Region, Russia
	R&D Magnets activities for CLIC Project have now entered a new phase with the design & manufacturing of several prototypes investigating the most challenging aspects of the CLIC Project. As concerning the CLIC Magnet System, challenges can be related to pure technical aspects (e.g. the Final Focus QD0 quadrupole where a gradient of more than 550 T/m is requested) or to industrial production choices (e.g. the Main Beam Quadrupoles where compactness and high tolerances are requested for the mechanical assembly, or the Drive Beam Quadrupoles where a productions of more than 40000 units is needed). In this paper the key aspects of the magnets under studies such as the Drive Beam, Main Beam and the Final Focus quadrupoles will be presented and discussed. Results on prototypes under assembly and measured performances will also be addressed.

THPC149	Development of PrFeB Cryogenic Undulator (CPMU) at SOLEIL	undulator, cryogenics, vacuum, storage-ring	3233
	C. Benabderrahmane, P. Berteaud, N. Béchu, L. Chapuis, M.-E. Couprie, J.P. Daguerre, J.-M. Filhol, C. Herbeaux, A. Lestrade, M. Louvet, J.L. Marlats, K. Tavakoli, M. Valléau, D. Zerbib SOLEIL, Gif-sur-Yvette, France
	A R&D programme for the construction of a 2 m long 18 mm period CPMU is under progress at SOLEIL. The cryogenic undulator will provide photons in the region of 1.4 to 30 keV. It will be installed in the next few months on the long straight section (SDL13) of the storage ring, and could be used later on to produce photons for the NANOSCOPIUM beamline. The use of PrFeB which features a 1.35 T remanence (Br) at room temperature enables to increase the peak magnetic field at 5.5 mm minimum gap, from 1.04 T at room temperature to 1.15 T at a cryogenic temperature of 77 K. Praseodymium was chosen instead of Neodymium magnetic material, because it is more resistant against the appearance of the Spin Reorientation Transition. Different corrections were performed first at room temperature to adjust the phase error, the electron trajectory and to reduce the multipolar components. The mounting inside the vacuum chamber enables the fitting of a dedicated magnetic measurement bench to check the magnetic performance of the undulator at low temperature. The results of the magnetic measurements at low temperature and the comparison with the measurement at room temperature are reported.

THPC151	The 65 mm Period Electromagnetic/Permanent Magnets Helical Undulator at SOLEIL	undulator, power-supply, electron, wiggler	3239
	F. Marteau, P. Berteaud, F. Bouvet, L. Chapuis, M.-E. Couprie, J.P. Daguerre, T.K. El Ajjouri, J.-M. Filhol, P. Lebasque, J.L. Marlats, A. Mary, K. Tavakoli SOLEIL, Gif-sur-Yvette, France
	SOLEIL prepares a new 65 mm period Electromagnetic/Permanent Magnets Helical Undulator (EMPHU), with a rapid switching at 5 Hz of the polarization required for dichroïsm experiments. The vertical field Bz is produced by coils fed by a fast switching power supply (designed and built in house), with a maximum current of 350 A and a polarity switching time shorter than 100 ms. The coils consist of 25 stacked copper layers shaped by water jet cutting. The current flows in 16 layers and 9 of them are cooled with thermal drain to a water piping. 4 additional power supplies feed 2 types of correction coils for the dynamic compensation of the field integrals, besides the ones for the termination. 1.28 T remanence NdFeB permanent magnets generate the horizontal field Bx. Peak Bz and Bx in the helical configuration reach 0.24 T at 14.7 mm minimum gap. Thermal modelling and measurements aim at keeping the magnet temperature constant. The static magnetic configuration was optimised using the ID_Builder software and the trajectory were checked for insuring a good reproducibility of the photon beam pointing when sweeping from one helicity to the other.

THPC154	Shimming of the Dynamic Field Integrals of the BESSY II U125 Hybrid Undulator	undulator, wiggler, electron, injection	3248
	J. Bahrdt, W. Frentrup, A. Gaupp, M. Scheer, I. Schneider, G. Wüstefeld HZB, Berlin, Germany
	Within a continuous program the BESSY II undulators are prepared for Topping-Up operation. The BESSY II U125 planar hybrid undulator has a period length of 125 mm and a pole width of only 60 mm. The horizontal defocusing of the 1.7 GeV e-beam may result in a significant reduction of the horizontal dynamic aperture, reducing the injection efficiency when injecting into the closed gap. The dynamic field integrals are derived from a 2D-Fourier decomposition of the 3D-field. An analytic description of the dynamic multipoles based on the Fourier coefficients is presented. Magic fingers have been installed in order to minimize the dynamic field integrals and to enlarge the good field region of the device.

THPC157	Hot-/Cold-Side Characterization of Asymmetric Undulator Magnets	undulator, magnet-design, induction, insertion	3257
	F.-J. Börgermann Vacuumschmelze GmbH & Co. KG, Hanau, Germany S. Marks LBNL, Berkeley, California, USA
	The homogeneity of permanent magnets for use in undulators is dominantly described by small variations in remanence (±1%) and magnetic angles (±1°). The definition and measurement of the so-called hot-/cold-side-effect has proven to be useful as characterization of higher order variations of the local field components. It is measured by a Hall probe at a distance of the half gap width from both magnet pole-surfaces. Typical results for a batch of magnets lie in a range of about ±2% or less. For symmetrical permanent magnet geometries, the distribution is symmetric about the value of zero. In a batch of magnets for a new EPU at LBNL, however, we found an asymmetric distribution of the hot-/cold-side-effect. This asymmetry is attributed to the geometrically asymmetric cut-outs inside the magnets used for fixture on the aluminum keepers. We present a theoretical model which can predict this asymmetric influence on the hot-/cold-side-effect resulting from these small geometric asymmetries. The method may also be used to pre-calculate corrected specification values for the near-field results for future undulator magnets.

THPC158	Field Optimization for Short Period Undulators	undulator, wiggler, insertion, damping	3260
	P. Peiffer, A. Bernhard KIT, Karlsruhe, Germany R. Rossmanith Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany D. Schoerling CERN, Geneva, Switzerland
	Undulators dedicated to low energy electron beams, like Laser Wakefield Accelerators, require very short period lengths to achieve X-ray emission. However, at these short period lengths (~5 mm) it becomes difficult to reach magnetic field amplitudes that lead to a K parameter of ~1, which is generally desired. Room temperature permanent magnets and even superconductive undulators using Nb-Ti as conductor material have proven insufficient to achieve the desired field amplitudes. The superconductor Nb3Sn has the theoretical potential to achieve the desired fields. However, up to now it is limited by several technological challenges to much lower field values than theoretically predicted. Alternatives for higher fields would be to manufacture the poles of the undulator body from Holmium instead of iron or to use Nb-Ti wires with a higher superconductor/copper ratio. The advantages and challenges of the different options are compared in this contribution.

THPC165	Estimations for Demagnetization of ID Permanent Magnets due to Installation of OTR	electron, radiation, simulation, undulator	3281
	Y. Asano RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan T. Bizen JASRI/SPring-8, Hyogo, Japan
	Demagnetization due to high energy electron irradiation is one of the crucial issues for stable operation of X-ray free electron laser (XFEL) and Synchrotron radiation (SR) facilities. Especially, during the commissioning, electron beam is scattered and then hits permanent magnets of insertion devices due to installation of some instrumentations such as OTR (Optical Transition Radiation) for beam diagnosis so that the estimation of demagnetization is very important to perform the commissioning smoothly. Fortunately, we found the index of demagnetization of Nd2Fe14B permanent magnets due to high energy electron irradiation. Star density produced by high energy photo-neutron reproduces experimental results of demagnetization. At SPring-8, in-vacuum type undulators have been employed for XFEL so that we estimate the demagnetization of the undulators for various cases such as electron energy in ranging from 2 GeV to 8 GeV and the permanent magnet gap from 2 mm to 40 mm. And we also estimate the allowable time to be able to insert the OTR.

THPC173	Modelization of Inhomogeneities in Permanent Magnet Blocks	undulator, insertion, insertion-device, simulation	3305
	V. Massana, J. Campmany, J. Marcos CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
	Nowadays one of the main objectives for insertion devices manufacturers is to reduce the gap of undulators as much as possible while keeping the features of the generated magnetic field. Because of that, the effects of magnetic blocks’ inhomogeneities are playing an increasing role in the quality of the whole device. In this paper we present a modelization of the inhomogeneities of permanent magnet blocks used to build wigglers and undulators. The model is based in splitting individual magnet blocks in different parts which are considered magnetically homogeneous. The model takes into account the relative orientation of magnet blocks assembled into their holders as well as local magnetic properties. We have applied the model to fit magnetic field integrals measured with a fixed stretched wire bench and magnetization data obtained from Helmholtz coils measurements for both single blocks and groups of blocks mounted on a common holder. The results of the model fit with experimental data within an rms error of 6•10^-4 mT•m for individual blocks and 1.5•10^-4 mT•m in the case of magnet groups.

Paper

Title

Other Keywords

Page

TUODA02

Status of Sirius – a New Brazilian Synchrotron Light Source

dipole, emittance, lattice, synchrotron

931

L. Liu, R. Basílio, J.F. Citadini, R.H.A. Farias, R.J.F. Marcondes, X.R. Resende, F. Rodrigues, A.R.D. Rodrigues, P.P. Sanchez, R.M. Seraphim, G. Tosin, F. H. de Sá
LNLS, Campinas, Brazil

We present an overview of the new synchrotron light source project Sirius, currently being designed at the Brazilian Synchrotron Light Laboratory (LNLS) in Campinas, São Paulo. Sirius will consist of a 480 m circumference, 3.0 GeV, 20 TBA cells, 1.7 nm.rad emittance storage ring. The dipoles will be based on the use of permanent magnet technology and will combine low field magnets (0.5 T) for the main beam deflection with a short slice of high field magnet (2.0 T) to generate photons of 12 keV critical energy with modest total energy loss. There will be 18 straight sections for insertion devices. In this report we describe the current status for the magnet lattice design and some of the subsystems.

Slides TUODA02 [2.434 MB]

TUODB03

Innovative Design of the Fast Switching Power Supplies for the SOLEIL EMPHU Insertion and its Fast Correctors

power-supply, controls, undulator, simulation

982

F. Bouvet, D. Aballea, R. Ben El Fekih, S. Bobault, M. Bol, Y. Bouanani, Y. Dietrich, A. Hardy, F. Marteau
SOLEIL, Gif-sur-Yvette, France

A new electromagnetic/permanent magnets helical undulator has been designed and is under commissioning at SOLEIL. For a fast switching of the photon polarization, it requires a power supply able to switch between +/350 A within 50 ms, without any current overshoot and with a very good current resolution over the full scale (50 ppm). The in-house design is based on two full switching bridges with interleaved commands. Combined with a regulation scheme using sophisticated algorithms, such a design enables to reach a high control bandwidth, permitting fast transitions. Such a fast and accurate system needs well performing digital control electronics. We chose the digital control cards developed at Paul Scherrer Institute (Villigen CH) for the SLS (Swiss Light Source). The components, measurements, interlocks, control interfaces, and electronic cards were developed and assembled together at SOLEIL. This paper will present the main lines of this development and the performances achieved during the EMPHU insertion commissioning. The design of the fast power supplies (±20 A) needed for corrector magnets of this insertion will also be presented.

Slides TUODB03 [3.017 MB]

TUPS087

Development of Permanent Magnet Focusing for Klystrons

klystron, cathode, focusing, target

1743

Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
S. Fukuda, T. Matsumoto, S. Michizono, M. Yoshida
KEK, Ibaraki, Japan

Funding: KEK
Applying permanent magnet technology to beam focusing in klystrons can reduce their power consumption and reliability. These features benefit variety of applications especially for large facilities that use number of klystrons such as ILC. A half scaled model will be available in summer and full model should be available in September. Research and Development status will be reported.

WEOBA03

Non-scaling Fixed Field Alternating Gradient Permanent Magnet Cancer Therapy Accelerator

acceleration, proton, cavity, lattice

1923

D. Trbojevic
BNL, Upton, Long Island, New York, USA
V.S. Morozov
JLAB, Newport News, Virginia, USA

Funding: Work performed under U.S. DOE Contract Number DE-AC02-98CH10886.
We present a design of the proton therapy accelerator from 31 MeV to 250 MeV by using racetrack lattice made of Non-Scaling Fixed Field Alternating Gradient (NS-FFAG) arcs and two parallel straight sections. The magnets in the arcs are separated function Halbach type magnets. The dipole bending field is 2.3 T, while the Neodymium Iron Boron magnetic residual induction is Br=1.3 T. The radial orbit offsets in the NS-FFAG arcs, for the kinetic energy range between 31 MeV < Ek < 250 MeV or momentum offset range -50% < δp/p < 50%, are -11.6 mm < x max < 16.8 mm, correspondingly. The straight sections used for the cavities and single turn injection/extraction kickers and septa are with zero orbit offsets. The permanent magnets accelerator should reduce overall and operating cost. It could fit into 8 x 12 m space.

Slides WEOBA03 [2.789 MB]

WEPO017

Status of CLIC Magnets Studies

quadrupole, linac, solenoid, acceleration

2433

M. Modena
CERN, Geneva, Switzerland
A.S. Vorozhtsov
JINR, Dubna, Moscow Region, Russia

R&D Magnets activities for CLIC Project have now entered a new phase with the design & manufacturing of several prototypes investigating the most challenging aspects of the CLIC Project. As concerning the CLIC Magnet System, challenges can be related to pure technical aspects (e.g. the Final Focus QD0 quadrupole where a gradient of more than 550 T/m is requested) or to industrial production choices (e.g. the Main Beam Quadrupoles where compactness and high tolerances are requested for the mechanical assembly, or the Drive Beam Quadrupoles where a productions of more than 40000 units is needed). In this paper the key aspects of the magnets under studies such as the Drive Beam, Main Beam and the Final Focus quadrupoles will be presented and discussed. Results on prototypes under assembly and measured performances will also be addressed.

THPC149

Development of PrFeB Cryogenic Undulator (CPMU) at SOLEIL

undulator, cryogenics, vacuum, storage-ring

3233

C. Benabderrahmane, P. Berteaud, N. Béchu, L. Chapuis, M.-E. Couprie, J.P. Daguerre, J.-M. Filhol, C. Herbeaux, A. Lestrade, M. Louvet, J.L. Marlats, K. Tavakoli, M. Valléau, D. Zerbib
SOLEIL, Gif-sur-Yvette, France

A R&D programme for the construction of a 2 m long 18 mm period CPMU is under progress at SOLEIL. The cryogenic undulator will provide photons in the region of 1.4 to 30 keV. It will be installed in the next few months on the long straight section (SDL13) of the storage ring, and could be used later on to produce photons for the NANOSCOPIUM beamline. The use of PrFeB which features a 1.35 T remanence (Br) at room temperature enables to increase the peak magnetic field at 5.5 mm minimum gap, from 1.04 T at room temperature to 1.15 T at a cryogenic temperature of 77 K. Praseodymium was chosen instead of Neodymium magnetic material, because it is more resistant against the appearance of the Spin Reorientation Transition. Different corrections were performed first at room temperature to adjust the phase error, the electron trajectory and to reduce the multipolar components. The mounting inside the vacuum chamber enables the fitting of a dedicated magnetic measurement bench to check the magnetic performance of the undulator at low temperature. The results of the magnetic measurements at low temperature and the comparison with the measurement at room temperature are reported.

THPC151

The 65 mm Period Electromagnetic/Permanent Magnets Helical Undulator at SOLEIL

undulator, power-supply, electron, wiggler

3239

F. Marteau, P. Berteaud, F. Bouvet, L. Chapuis, M.-E. Couprie, J.P. Daguerre, T.K. El Ajjouri, J.-M. Filhol, P. Lebasque, J.L. Marlats, A. Mary, K. Tavakoli
SOLEIL, Gif-sur-Yvette, France

SOLEIL prepares a new 65 mm period Electromagnetic/Permanent Magnets Helical Undulator (EMPHU), with a rapid switching at 5 Hz of the polarization required for dichroïsm experiments. The vertical field Bz is produced by coils fed by a fast switching power supply (designed and built in house), with a maximum current of 350 A and a polarity switching time shorter than 100 ms. The coils consist of 25 stacked copper layers shaped by water jet cutting. The current flows in 16 layers and 9 of them are cooled with thermal drain to a water piping. 4 additional power supplies feed 2 types of correction coils for the dynamic compensation of the field integrals, besides the ones for the termination. 1.28 T remanence NdFeB permanent magnets generate the horizontal field Bx. Peak Bz and Bx in the helical configuration reach 0.24 T at 14.7 mm minimum gap. Thermal modelling and measurements aim at keeping the magnet temperature constant. The static magnetic configuration was optimised using the ID_Builder software and the trajectory were checked for insuring a good reproducibility of the photon beam pointing when sweeping from one helicity to the other.

THPC154

Shimming of the Dynamic Field Integrals of the BESSY II U125 Hybrid Undulator

undulator, wiggler, electron, injection

3248

J. Bahrdt, W. Frentrup, A. Gaupp, M. Scheer, I. Schneider, G. Wüstefeld
HZB, Berlin, Germany

Within a continuous program the BESSY II undulators are prepared for Topping-Up operation. The BESSY II U125 planar hybrid undulator has a period length of 125 mm and a pole width of only 60 mm. The horizontal defocusing of the 1.7 GeV e-beam may result in a significant reduction of the horizontal dynamic aperture, reducing the injection efficiency when injecting into the closed gap. The dynamic field integrals are derived from a 2D-Fourier decomposition of the 3D-field. An analytic description of the dynamic multipoles based on the Fourier coefficients is presented. Magic fingers have been installed in order to minimize the dynamic field integrals and to enlarge the good field region of the device.

THPC157

Hot-/Cold-Side Characterization of Asymmetric Undulator Magnets

undulator, magnet-design, induction, insertion

3257

F.-J. Börgermann
Vacuumschmelze GmbH & Co. KG, Hanau, Germany
S. Marks
LBNL, Berkeley, California, USA

The homogeneity of permanent magnets for use in undulators is dominantly described by small variations in remanence (±1%) and magnetic angles (±1°). The definition and measurement of the so-called hot-/cold-side-effect has proven to be useful as characterization of higher order variations of the local field components. It is measured by a Hall probe at a distance of the half gap width from both magnet pole-surfaces. Typical results for a batch of magnets lie in a range of about ±2% or less. For symmetrical permanent magnet geometries, the distribution is symmetric about the value of zero. In a batch of magnets for a new EPU at LBNL, however, we found an asymmetric distribution of the hot-/cold-side-effect. This asymmetry is attributed to the geometrically asymmetric cut-outs inside the magnets used for fixture on the aluminum keepers. We present a theoretical model which can predict this asymmetric influence on the hot-/cold-side-effect resulting from these small geometric asymmetries. The method may also be used to pre-calculate corrected specification values for the near-field results for future undulator magnets.

THPC158

Field Optimization for Short Period Undulators

undulator, wiggler, insertion, damping

3260

P. Peiffer, A. Bernhard
KIT, Karlsruhe, Germany
R. Rossmanith
Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
D. Schoerling
CERN, Geneva, Switzerland

Undulators dedicated to low energy electron beams, like Laser Wakefield Accelerators, require very short period lengths to achieve X-ray emission. However, at these short period lengths (~5 mm) it becomes difficult to reach magnetic field amplitudes that lead to a K parameter of ~1, which is generally desired. Room temperature permanent magnets and even superconductive undulators using Nb-Ti as conductor material have proven insufficient to achieve the desired field amplitudes. The superconductor Nb3Sn has the theoretical potential to achieve the desired fields. However, up to now it is limited by several technological challenges to much lower field values than theoretically predicted. Alternatives for higher fields would be to manufacture the poles of the undulator body from Holmium instead of iron or to use Nb-Ti wires with a higher superconductor/copper ratio. The advantages and challenges of the different options are compared in this contribution.

THPC165

Estimations for Demagnetization of ID Permanent Magnets due to Installation of OTR

electron, radiation, simulation, undulator

3281

Y. Asano
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
T. Bizen
JASRI/SPring-8, Hyogo, Japan

Demagnetization due to high energy electron irradiation is one of the crucial issues for stable operation of X-ray free electron laser (XFEL) and Synchrotron radiation (SR) facilities. Especially, during the commissioning, electron beam is scattered and then hits permanent magnets of insertion devices due to installation of some instrumentations such as OTR (Optical Transition Radiation) for beam diagnosis so that the estimation of demagnetization is very important to perform the commissioning smoothly. Fortunately, we found the index of demagnetization of Nd2Fe14B permanent magnets due to high energy electron irradiation. Star density produced by high energy photo-neutron reproduces experimental results of demagnetization. At SPring-8, in-vacuum type undulators have been employed for XFEL so that we estimate the demagnetization of the undulators for various cases such as electron energy in ranging from 2 GeV to 8 GeV and the permanent magnet gap from 2 mm to 40 mm. And we also estimate the allowable time to be able to insert the OTR.

THPC173

Modelization of Inhomogeneities in Permanent Magnet Blocks

undulator, insertion, insertion-device, simulation

3305

V. Massana, J. Campmany, J. Marcos
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

Nowadays one of the main objectives for insertion devices manufacturers is to reduce the gap of undulators as much as possible while keeping the features of the generated magnetic field. Because of that, the effects of magnetic blocks’ inhomogeneities are playing an increasing role in the quality of the whole device. In this paper we present a modelization of the inhomogeneities of permanent magnet blocks used to build wigglers and undulators. The model is based in splitting individual magnet blocks in different parts which are considered magnetically homogeneous. The model takes into account the relative orientation of magnet blocks assembled into their holders as well as local magnetic properties. We have applied the model to fit magnetic field integrals measured with a fixed stretched wire bench and magnetization data obtained from Helmholtz coils measurements for both single blocks and groups of blocks mounted on a common holder. The results of the model fit with experimental data within an rms error of 6•10^-4 mT•m for individual blocks and 1.5•10^-4 mT•m in the case of magnet groups.