Magnet designs for the ESRF-SR2 Compact and Low Consumption Magnet Designs for Future Linear and Circular Colliders Geneva, November 26-28, 2014 Magnet designs for the ESRF-SR2 G. Le Bec, J. Chavanne

Introduction: the ESRF-SR2 OUTLINE Introduction: the ESRF-SR2 Generalities about compact and efficient magnets Reducing the aperture Minimum aperture magnets Permanent magnets? Compactness and power efficiency for the ESRF-SR2 PM dipole with longitudinal gradient EM high gradient quadrupole EM combined dipole-quadrupole Conclusion G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

OUTLINE Introduction G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Reduced horizontal emittance: 4000  147 pm.rad Introduction ESRF Upgrade Phase II Reduced horizontal emittance: 4000  147 pm.rad Same insertion devices source points New storage ring Increased number of magnets: 7-bend achromat Reduced longitudinal space Reduced power consumption G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

ESRF Upgrade Phase II magnets: one cell Introduction ESRF Upgrade Phase II magnets: one cell 32 cells ~1000 magnets (without correctors) G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

High gradient quads (up to 85 T/m) High gradient combined magnets Introduction Design challenges High gradient quads (up to 85 T/m) High gradient combined magnets Dipoles with longitudinal gradient Longitudinal compactness required Integration of vacuum chambers and beam ports G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

OUTLINE Compact and efficient magnets Reducing the aperture Compactness and power consumption G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Small aperture magnets Power consumption and bore radius If the magnets are not saturated: Dipole power consumption  g 2 Quadrupole power consumption  R 4 Sextupoles power consumption  R 6 Low power and compactness  Reduced magnet apertures Main limitations Integration: vacuum chambers, beam ports, etc. Sensitivity to mechanical errors Compact magnet Minimum aperture reached Compactness refers to the external dimensions G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Small aperture magnets Mechanical error Assembly errors Errors at the GFR boundary Multipolar error at the bore radius Bore radius (GFR radius = r) Error @ r =R/4 r0=R r0=R/2 Quadrupolar e2 4e2 Sextupolar e3 8e3 Octupolar e4 16e4 Compact & low consumption  Tigh mechanical tolerances G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Compactness… in which direction? Compact magnets Compactness… in which direction? At constant integrated field (in first approximation: no saturation, no flux leakage, etc.) Transverse size variation is much faster if the magnet is saturated H L Compromise Longitudinal compactness Transverse compactness (also true for EM magnets) G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Transverse Compactness vs. Power consumption WYOKE WPOLE WCOIL HCOIL Fixed parameters NI WPOLE & WYOKE WCOIL (magnet length is fixed) Compact Low power High J Low J G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Length, transverse dimensions AND Power consumption Fixed integrated gradient: 50 T Variable length Variable NI and outer radius Bore radius: 12.5 mm Constant current density: 5 A/mm2 G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Compact and efficient magnets Normal conducting vs. permanent magnets OUTLINE Compact and efficient magnets Normal conducting vs. permanent magnets G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Short period undulator Lattice magnets PM micro-motor PM DC motor Asynchronous motor Power plant generator mm m Short period undulator Lattice magnets G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

scale factor g g g g g Characteristic aperture (g0 is obviously design dependent, this is a very first approximation) Gap < a few centimeters PM dipoles are more compact than EM dipoles G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

More compact for small aperture magnets Permanent magnets PM systems advantages More compact for small aperture magnets No coil head: iron length = magnet length No power consumption But… Risk of radiation damage? No if Sm2Co17 material is used Temperature variation? Can be compensated passively Mechanical complexity, tolerance stack-up Limited tunability G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Mechanical complexity Permanent magnets Mechanical complexity Yoke+pole: rigid assembly Yoke+pole: different parts Need spacers Tolerance stack-up Not compatible with laminated designs G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Permanent magnets Tunability h Trimming coils Permanent magnets = air gaps for coils Field in the gap: Optimization of PM volume: Coil field at optimum PM dimensions: x2 Amp turns needed! wY Yoke wP g Coils G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Permanent magnets Tunability x1 x2 w h Trimming coils Similar result for quad (Tosin, NIMA 2012) Optimization of PM volume: Coil induced gradient at optimum PM dimensions: where G0 is the gradient obtained without PM Coil efficiency reduced by a factor 2 G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Permanent magnets Tunability 10% of these Amp turns 5% tuning range G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Permanent magnets tunability Moving parts? Gap motions on insertion devices: 100% field tunability But… Field quality and magnet centre may depends on the position of the moving parts Possible reliability issues (may be improved using stepper motors) Accuracy of mechanical assembly is not easy to reach, even without motion Complex mechanical system high cost G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Outline Compactness and power efficiency for the ESRF-SR2 Dipoles with longitudinal gradient (DL) G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

ESRF dipole with longitudinal gradient (DL) Field ranging from 0.17 T up to 0.55 T or 0.67 T Total length: 1.85 m Gap: 25 mm Magnet mass: 400 kg PM Mass: 25 kg/Sm2Co17 and 25 kg Strontium ferrite per dipole (Design and measurements of the DL magnet: J. Chavanne) G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

ESRF dipole with longitudinal gradient (DL) Aluminium spacers Iron pole and yoke PM blocks DL module Number of PM blocks is module dependent Temperature compensation is not shown here Complete DL magnet on its support G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

ESRF dipole with longitudinal gradient (DL) Homogeneity of central field Quality dominated by pole faces parallelism May need refinement of mechanical tolerances Easy and fast mechanical correction (shimming) Tolerance: DB/B < 10-3 @13 mm Module 1 without shims (Hall probe meas.) Module 2 without shims (Hall probe meas.) G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

ESRF dipole with longitudinal gradient (DL) Integrated field Preliminary study on straight integrals Stretched wire method Two modules with 0.62 T and 0.41 T Longitudinal gap 5 mm between poles End effect (sextupole) shims not installed Will improve with additional modules G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

ESRF dipole with longitudinal gradient (DL) Longitudinal field Flat top field at longitudinal gap gs = 5 mm The optimum gs may change between the modules of the full magnet (field step dependence) gs G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Outline Compactness and power efficiency for the ESRF-SR2 High gradient quadrupoles G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

High gradient quadrupoles ESRF-SR2 85 T/m nominal gradient 12.8 mm bore radius, 0.5 m long Normal conducting Longitudinal compactness optimized 90 A, 69 turns Low power consumption (1.6 kW) Total mass ~1 ton Fast pole shaping algorithm developed Prototype being manufactured 600 mm 600 mm 500 mm G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

High gradient quadrupoles Excitation curves and saturation Moderate gradient quads optimized at a linear working point High gradient quads optimized at a saturated working point 1.5 T 2 T 1.5 T 1 T 1 T 0.5 T 0.5 T (a) (b) Magnetization m0M [T] of a moderate gradient (a) and high gradient (b) quadrupoles at nominal current. Excitation curves G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

High gradient quadrupoles Energy savings and compactness Low power quadrupole Compact quadrupole Current density 3.25 5 A/mm2 Power 1.65 2.50 kW Height 605 535 mm Mass 860 740 kg G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Outline Compactness and power efficiency for the ESRF-SR2 Combined dipole-quadrupoles (DQ) G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Combined Dipole-Quadrupoles Bz Bz x x Tapered dipole High field, low gradient Offset quadrupole High field, high gradient G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Combined Dipole-Quadrupoles Bz x DQ specifications GFR radius 7 mm Field 0.54 T Gradient 34 T/mm Offset quadrupole High field, high gradient G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Combined Dipole-Quadrupoles Field of an offset quad GFR x Bz Region of interest Additional power consumption, weight, etc. G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Combined Dipole-Quadrupoles A new target for DQ field Pro Lower power consumption and weight Easy access on one side (vacuum chamber, magnetic measurements) Cons Design and construction are more complex GFR x Bz G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Combined Dipole-Quadrupoles Single-sided dipole-quadrupole 2 poles + 2 “half” poles 0.54 T field, 34 T/m gradient Iron length: 1.1 m Magnet mass ~ 1 ton Power consumption: 1.5 kW Main pole Main coil Auxiliary pole Auxiliary coil (in series with main coil) Trimming coil G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Combined Dipole-Quadrupoles Magnetic design GFR Vertical field vs. position. Field is almost zero on one side. DG/G expressed in 10-3. Specification: DG/G < 10-2. GFR: 7x5 mm Field integration along an arc. G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Combined Dipole-Quadrupoles Energy savings and compactness Single-side DQ vs. offset quadrupole Single-sided DQ Compact offset quadrupole Low power offset quadrupole Current density 3.25 5 A/mm2 Power 1.5 3.9 2.5 kW Width x height 330 x 470 415 x 415 465 x 465 mm Mass 900 940 1050 kg G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Compactness and efficiency Small aperture magnets (tight tolerances) Conclusions Compactness and efficiency Small aperture magnets (tight tolerances) Trade off between compactness and power consumption Trade off between length and transverse dimensions PM magnets? Good choice if reduced a tuning range is accepted (coil efficiency x1/2 for dipole and quadrupoles) Tight tolerances to be anticipated (more parts, tolerances stack-up) ESRF-SR2 magnets: lower power and compact designs Dipole with longitudinal gradient: PM, compact, no power consumption Quadrupoles: low power, not so compact Combined dipole-quadrupoles: low power, single-sided design G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014

Many thanks for your attention G. Le Bec, Magnet designs for the ESRF-SR2, Compact and Low Consumption Magnets Workshop, Geneva, November 2014