Superconducting Septa and Fast Ramped cos(θ) Magnets

Transcription

1 Superconducting Septa and Fast Ramped cos(θ) Magnets K. Sugita, E. Fischer, H. Müller, P. Schnizer Superconducting Magnets and Testing Group, Primary Beams, GSI March 2015 FCC Week 2015 Washington D.C. USA

2 Contents Introduction 1. Superconducting magnets in SIS Superconducting septum magnet for the SIS300 extraction a) Concept and theory b) Conceptual 2D design c) Magnet end design 3. Further design options and realization aspects a) Quadrupole and combined function septum magnets b) Nuclotron cable for high field magnets Summary 2

3 Introduction: FAIR accelerator complex International collaboration SIS18 SIS100/300 SIS300 Extraction Compared to GSI existing facility Primary beam intensities: 100 Secondary beam intensities: Primary beam energies: 10 Antiproton production Schedule for Start version: SIS100, Super-FRS, CBM/HADES, APPA, NuSTAR, PANDA 2019 FAIR Accelerator installed 2020 Facility operational 3

4 Superconducting Magnets in SIS300 SIS300 is not part of the start version of FAIR later integration is considered in civil construction plannings currently small scale R&D work Dipoles: 48/12 (long / short) cos( ) type curved 1 layer coil usable aperture circular, 86 mm low loss Rutherford cable small NbTi filaments (2.5 µm) 36 strands, mm Ø CuMn interfilamentary matrix stainless steel core between layers 4

5 Superconducting Magnets in SIS300 Dipole magnet development at INFN, Italy (Discorap, EU-CRISP ) Inner diameter of coil mm 100 Eff. Magnet Length m 7.757/3.879 Curvature Radius m 66.7 Max. Magnetic Field T 4.5 Max. Ramp Rate T/s 1 Operation current A 8920 Peak field on coil T 4.9 Key technology Low loss superconducting strand Fast-ramp cosine-theta curved magnet SIS300 Dipole in Cryostat Status: Prototype magnet was built and successfully tested in collaboration with INFN 5

6 Superconducting Magnets in SIS300 Main Quadrupole: Cable Parameters Number of strand 19 Strand diameter, mm 0,825 Cable width, mm 8,25 Cable middle thickness, mm 1,45 Transposition pitch, mm 60 Coating of strands Sn+5%Ag Stainless steel core, m 25 Rc (Ra), mω 500 (0.01) Insulation (polyimide film): 3 layers 25 m 1 layer 55 m Cable critical current, (5T; 4.2K; 1 V/cm, UNK wire), ka Cable critical current (5T; 4.2K; 1 V/cm, Bochvar wire, ka) 130 m

7 Superconducting Magnets in SIS300 Quadrupole/corrector magnets development at IHEP, Russia Inner diameter of coil mm 125 Eff. Magnet Length m 1 Max. Mag. Field Gradient T/m 45 Max. Ramp Rate T/m/s 10 Operation current A 6260 Peak field on coil T 3.51 Status: Prototype (2 quadrupole,1 steering) magnets were built and tested successfully. (Steering magnet) GSI will continue R&D programs for SIS300 together with international partners INFN, IHEP, Bochvar 7

8 Contents Introduction 1. Superconducting magnets in SIS Superconducting septum magnet for the SIS300 extraction a) Concept and theory b) Conceptual 2D design c) Magnet end design 3. Further design options and realization aspects a) Quadrupole and combined function septum magnets b) Nuclotron cable for high field magnets Summary 8

9 -60 y [mm] +60 SC Septum for SIS300 Extraction Dipole field 3.65 T, effective length 4 m, Curved Magnet Magnetic Septa Beam direction Circulating beam Electrostatic septa Lambertson septum Kicker modules SIS300 Superconducting Septum Beam direction Preliminary design Circulating beam direction 9

10 SC Septum for SIS300 Extraction Design options: a) Normal-conducting, conventional design: Iron saturation, stray field b) Superconducting Preceding studies Concept Truncated double cosine theta superconducting magnet [1], [2] (no iron): Realization BNL g-2 inflector [3] (no iron) [1] F. Krienen et al., The truncated double cosine theta superconducting septum magnet, Nucl. Instr. and Meth., vol. A283, pp. 5 12, [2] F. Krienen, MagneticFieldGenerator, U.S.Patent , July3, [3] A. Yamamoto et al., The superconducting inflector for the BNL g-2 experiment, Nucl. Instr. and Meth., vol. A491, pp ,

11 SC Septum for SIS300 Extraction BNL g-2 inflector No iron, small aperture SIS300 Extraction Iron yoke, large aperture How to do? outer current of a truncated single cosine theta magnet is replaced by image current of an iron yoke. By taking limit (iron yoke radius goes to cosine theta current radius) all the currents correspond. Total current (Ampere turn) is a half of truncated single cosine theta magnet. 11

12 Zero Field Zero Field Zero Field SC Septum for SIS300 Extraction Superconducting Septum Magnet Simple model (numerical, no FEM) Simple model (numerical, no FEM) line line currents + image + image currents currents turns turns per per pole pole Draw flux flux lines lines (equipotential lines) lines) the in the aperture aperture Truncated iron-yoked cosine-theta Well-known cosine-theta Image current Real current A A θ t = π/2 A Yoke boundary θ t > π/2 θt < π/2 Almost all the flux lines are captured in in region A A 12

13 B SIS300 Septum Magnet: 2D Design Comparison of two coils θt > π/2 or θt < π/2 θt < π/2 type Iron yoke is necessary! (for image current, flux return) Extracted beam Cons More Ampère turn More dead space Difficulty of coil end Pros Thin septum thickness Better field quality (?) θt =60 No iron Iron yoke can be cut partly 13

14 SIS300 Septum Magnet: 2D Design Conceptual design Curved Magnet (tight space limitation) Truncated Iron-yoked Cosine-Theta Magnet Two-in-one magnet: Circulating beam - Extracted beam Optimized with Roxie Iron Yoke Extracted Beam Circulating Beam 493mm 14mm Maximum magnetic field in the iron 3.45T 14

15 B SIS300 Septum Magnet: 2D Design 15

16 SIS300 Septum: Magnet end design Next step: 3D coil end design cosine-theta + bedstead combined coil end 16

17 SIS300 Septum: Magnet end design Iron yoke magnet end middle part, cross section Circulating Beam Extracted Beam Iron Yoke Iron Yoke Cut off for bedstead end Yoke end Cut off may be omitted by optimized coil end design. 17

18 SC Septum for SIS300 Extraction 18

19 Contents Introduction 1. Superconducting magnets in SIS Superconducting septum magnet for the SIS300 extraction a) Concept and theory b) Conceptual 2D design c) Magnet end design 3. Further design options and realization aspects a) Quadrupole and combined function septum magnets b) Nuclotron cable for high field magnets Summary 19

20 Further Design Options 20

21 Further Discussion Design for realization Options and and Cables Nuclotron cable cable for for high high field field magnets magnets (and fast ramping) Insulations Fixation wire Sc. strands Cooling tube 2 phase Helium [1] A. Kovalenko, Workshop on Accelerator Magnet Superconductors, Archamps, France, Mar 2004, pp GSI-JINR Design Study: 4.0 T Single Layer Dipole Yoke 1.9 T 0.3 T [Design Option] Yoke SIS100 Dipole Magnet SIS100 Steering Magnet Superferric, window frame type type Cosine-theta type (H/V nested) Fast-Ramp, Truncated, Iron-yoked, cosine-theta septum magnet 17 21

22 Further Options and Realization Main Design Aspects Field quality: trade-off Ideally the iron yoke radius should be as close as possible to the cosine-theta current radius. By introducing the non-magnetic collar to avoid effect of iron saturation, field quality may be degraded. Cable design: Keystoned cable, flat cable or Nuclotron cable Coil end design Magnetic force: maintained by the septum wall 22

23 Summary The first superconducting prototype magnets for the SIS300 accelerator are built and tested successfully (1 dipole, 2 quadrupoles,1 steering magnet) A high field superconducting septum magnet for the SIS300 extraction is considered as a truncated, iron-yoked cosine-theta A high field superconducting septum magnet for the SIS300 extraction is type magnet. considered as a truncated, iron-yoked cosine-theta type magnet. After conceptual verification with simple line current models, After conceptual verification with simple line current models, preliminary 2D preliminary and coil end design 2D and have coil done. end design have done. Further optimizations from theoretical and practical (manufacturing) aspects are still necessary. Further optimizations from theoretical and practical (manufacturing) aspects are still necessary. Truncated, iron-yoked cosine-theta type magnet might be a candidate of a Truncated, iron-yoked cosine-theta type magnet might be a septum magnet for future circular colliders as well. candidate of a septum magnet for future circular colliders as well. Thank you for your attention eference Main References for Septa: 1] [1] K. K. Sugita, Novel Novel concept concept of truncated of iron-yoked cosine cosine theta theta magnets magnets and design and design studies studies for FAIR for septum FAIR septum magnets, EEE magnets, Trans. on IEEE Appl. Trans. Supercond. Appl. vol. Supercond. 22, no. 3, June vol , no. 3, June ] [2] K. K. Sugita, Sugita, Improved Septum Septum Magnet, Magnet, EU Patent, EU Patent, Appl. Appl. No. EP , No. EP , Sept 06, Sept , GSI GSI Helmholtzzentrum für für Schwerionenforschung GmbH 1923