Development of a Hybrid Permanent Magnet Quadrupole CERN

Development of a Hybrid Permanent Magnet Quadrupole CERN Workshop on special compact and low consumption magnet design November 2014 P. N’gotta, J. Chavanne, G. Le Bec P. N’gotta 1

Outline Future ligth source magnets § Driving criteria § Review of design proposed Magnet design § Specifications § constraints § Magnets performances Prototype § Assembly § Results Conclusion P. N’gotta 2

Introduction 4 GLS magnets requirement Dipoles Quadrupoles § Small apertures § Low field dipoles § High gradient quadrupoles P. N’gotta 3

Introduction For example: ESRF Upgrade S 10 Lattice Specificity: Limited longitudinal space P. N’gotta 4

Introduction Future ligth source magnets design criteria: • Strong multipolar field • Compactness • Tight mechanical tolerances (small bore radius) • Low power consumption (operational cost) P. N’gotta 5

magnet design examples Current quadrupoles prototypes: CLIC final focusing CLIC Beam drive Decelerator • Iron dominated, PM + coils • Gradient 525 T/m • Aperture 8. 25 mm • Tuning Range 80 % • Iron dominated, PM • Gradient 60. 4 T/m • Aperture 27. 2 mm • Tuning Range 75 % B. J. A. SHEPHERD, Daresbury, IPAC 2012 M. MODENA, CERN, IPAC 2012 SIRIUS quadrupole ILC final focusing • Iron dominated, PM + coils • Gradient 28 T/m • Aperture 55 mm • Tuning Range 30 % G. TOSIN, LNLS, PRST-AB 2012 • PM • Gradient 120 T/m • Aperture 20 mm • Tuning BY 7 T/m steps Y. IWASHITA, Kyoto, EPAC 2006 P. N’gotta 6

High gradient quadrupole specifications Based on ESRF-II high gradient quadrupole characteristics Specifications • Gradient: 100 T/m • Bore radius: 12 mm • Asymmetric GFR radius: 7 mm & 5 mm • ΔG/G 0 <10 ־ ³ • Length: 226 mm Halbach ? Resistive Constraints • Vertical gap: 10 mm • Compactness • Assembly Simplicity Hybrid (Iron dominated + PM) P. N’gotta 7

Magnets performances Choice of the structure Magnets performances/compactness comparison Halbach Hybrid Resistive Simulation models parameters • Bore radius: 19 mm • Current density: 4 A/mm 2 • Magnet Nd. Feb 1. 2 T • Halbach magnet number: 16 Gradient vs Transverse diameter PM structures Performances and compactness P. N’gotta 8

Magnets performances Choice of the structure Magnets field quality comparison q Field sensitivity essentially driven by PM errors q Random PM errors applied Simulation models constraints • Bore radius: 19 mm • GFR : 19 mm*3/4 • ΔG/G <10 ־ ³ Angle Remanent induction Dimension Halbach < 0. 05° < 1. 5% < 30µm Hybrid (Iron+PM) < 1° < 3% < 50µm PM tolerances errors Halbach structure Sensitive to PM errors P. N’gotta 9

Magnets performances summary Resistive Hybrid Halbach Field strength Compactness __ + ++ Field quality ++ + __ Hybrid structure Good compromise between performances criteria P. N’gotta 10

Hybrid quadrupole design H-type structure, simple mechanical parts Characteristics • 36 Nd. Fe. B magnets (Br =1. 1 T) • Steel ARMCO • Simple and flexible structure • Simple magnet block shape • Magnets far from electron beam (radiation damage protection) • 3 D optimization • Gauss-Newton algorithm + SVD • Result in 5 iterations (<10 min) • Large space for X-rays beam port, extension possibility (Le Bec et al. , IPAC 14) Iron Magnet P. N’gotta 11

Hybrid quadrupole prototype • PM mass: 12 kg • Iron mass: 25 kg 210 mm Characteristics Field correction shim m • Total mass : 45 kg 23 0 m • 1 hour for assembly ( before shimming) 160 mm P. N’gotta 12

Hybrid quadrupole prototype Results • Stretch wire method • Nominal gradient: 82 T/m • Field quality (harmonics) @ 7 mm, GFR P. N’gotta 13

Hybrid quadrupole prototype Field tuning Flexible structure • Required space for coil by moving magnets • Possibility to reach large field tuning • But with nominal gradient decrease • Compromise to be found Br =1. 2 T • 5 mm magnet translation • Current density: 1 A/mm 2 • Field tuning: 1% P. N’gotta 14

Conclusion H-type Hybrid structure : • Possible structure for future ligth source • Strong gradient & compactness • Simple field correction • Easy assembly • Possibility to implement tuning coils • No power consumption Prospects : • Mechanical improvement • Field tuning • Temperature compensation • Correction tools improvement P. N’gotta 15

Thanks for your attention

Field tuning appendix Without tuning With tuning P. N’gotta