ILC Main Linac Superconducting Magnets

1. ILC Main Linac Superconducting Magnets V. Kashikhin for ILC Magnet Group June 6, 2006

2. Superconducting Magnets • Main Linac quadrupoles • Horizontal and Vertical Dipole correctors • Skew quadrupoles ILC Main Linac superconducting magnets

3. Main Linac Quadrupoles ILC Main Linac superconducting magnets

4. Main Linac Cryomodule Central support 300 mm pipe SCRF SCRF Quadrupole ILC Main Linac superconducting magnets

5. TESLA Quadrupoles TESLA 60 T/m Quadrupole TESLA 20 T/m Superferric Quadrupole ILC Main Linac superconducting magnets

6. Quadrupoles for Main Linac • ILC Main Linac Quadrupoles • Low current (50 –100 A) • Aperture 78 mm • Gradient 54 T/m • Length ~ 0.66 m • Adjustable field -20% • Quantity 428 • Magnetic center stability better than 2 μm • Low fringing fields: 1 μT during SCRF cooling down • 10 μT during SCRF operation • Possible issues: • - magnetic center motion (SC magnetization, Lorentz forces, mechanics, iron saturation and hysteresis, etc) • - fringing field trapped in SCRF at cooling down and operation substantially reduces Q quality factor SCRF Calculated 2-4 μm magnetic center displacement in quadrupole with dipole correctors ILC Main Linac superconducting magnets

7. Dipole Correctors for Main Linac • Three versions of correctors: • Combined with main quadrupole (TESLA,CIEMAT) • Stand alone shell type dipoles+skew correctors • Stand alone window-frame type dipoles+skew correctors Proposal: 1. Separate main quadrupole and dipole correctors to eliminate coupling effects 2. Move quadrupole+corrector in space between cryomodules ILC Main Linac superconducting magnets

8. Shell Type Dipole Corrector Magnet Parameters Integrated field 0.02 T-m Center field 0.29 T(both coils) 0.2 T/coil Winding ampere-turns 18kA Current 90 A Superconductor NbTi SC diameter 0.5 mm Outer diameter 140 mm Magnet length ~ 200 mm Flux density and flux lines at max current in both dipole coils Field homogeneity at max current in both dipole coils (+/- 1% at R< 30mm) Advantages: Compact radial dimensions Effective winding Low fringing fields in radial directions Disadvantages: Long coil ends ~ 50 mm (bedstead coils?) Very short strait coil part Long end fields +50mm/end Complicated winding ILC Main Linac superconducting magnets

9. Window-Frame Dipole Corrector Magnet Parameters Integrated field 0.02 T-m Center field 0.2 T(both coils) 0.14 T/coil Winding ampere-turns 12 kA Current 60 A Superconductor NbTi SC diameter 0.5 mm Shield outer diameter 320 mm Magnet length ~ 150 mm Flux density and flux lines at max current in both dipole coils Field homogeneity at max current in both dipole coils (+/- 1% at R< 30mm) Advantages: Compact longitudinal dimensions Simple coil and yoke manufacturing, assembly Short coil ends Good integrated field quality Good SC coil stability Disadvantages: Radial ferromagnetic shield Thicker iron yoke ILC Main Linac superconducting magnets

10. Window-Frame Dipole Corrector 3D Analysis Magnet Parameters Integrated field 0.017 T-m Center field 0.1 T(one coil) Dipole ampere-turns 9 kA Current 60 A Superconductor NbTi SC diameter 0.5 mm Shield outer diameter 320 mm Magnet length ~ 150 mm Dipole coil, yoke and shield geometry Integrated field at 9 kA total current in one dipole coil (0.3% homogeneity at R< 30mm) Magnet effective length is 180 mm Coil number of turns 150 Coil max field 0.15 T Dipole inductance 15 mH 3D Field calculations showed the 0.3% integrated field homogeneity at 30 mm aperture radius. This is a good result for the very short magnet ILC Main Linac superconducting magnets

11. Summary • Linac superconducting magnets are feasible • R&D and prototyping are needed to confirm the specified performance and cost estimation • Cost estimation can be made on the base of CERN correctors and TESLA • prototype magnets • Main issues: • - Magnetic center stability during –20% field change • - Combined or stand alone correctors • - Fringing fields in SCRF areas ILC Main Linac superconducting magnets