1. SIS 100 main magnets G. Moritz, GSI Darmstadt (for E. Fischer, MT-20 4V07)) Cryogenic Expert Meeting, GSI, September 19/20 2007

2. Main sc magnets of the synchrotron SIS 100

3. 3334 W 7623 W 533 W 2078 W 1361 W static load @ 4K beam induced loss dynamic load @ 4K liquefaction static load @ 50-80K (4K equivalent) Example: Cryogenic load distribution of the Synchrotrons SIS 100/200 (maximum load)

4. AC loss contributions (dynamic heat load) Magnet iron yoke (hysteresis loss) Structural elements (hysteresis and eddy current loss) Beam pipe (eddy current loss) Conductor (hysteresis and eddy current loss )

5. Mechanical structure / lifetime of the magnets SIS100 : 200 millions cycles within 20 years SIS 300: 1 million cycles within 20 years minimization of movement of any part R&D on material fatigue, crack propagation Main R&D Topics for rapidly-cycling magnets (Hz-range) Eddy and persistent currents affect field quality produce large steady-state AC-losses in coil, yoke, structural elements, beam pipe minimization of these effects good heat removal

6. SIS 100 superferric dipole iron-dominated superferric design (window frame type) cold iron maximum field: 1.9 T ramp rate: 4 T/s 3 m long, 16 turns based on Nuclotron dipole Collaboration: JINR (Dubna) 1- cooling tube, 3 - Superconducting wire, 3 - NiCr wire, 4 - Kapton tape, 5 – adhesive Kapton tape hollow-tube superconducting cable with low hydraulic resistance two-phase helium cooling strands indirectly cooled compact, low cost design

7. example: calculation of hysteresis loss in the brackets AC loss reduction (model magnets / FEM- calculations) 70% of the Nuclotron dipole losses are in the yoke!!! Experimental studies on model magnetsTheoretical ANSYS calculations example: loss reduction by slitting the pole and reduce brackets material

8. Modifications:  removed brackets  laser cut lamination slits  minimized coil ends R & D Results: AC loss reduction @ 4 K assumption for 20years operation costs comparison study: nc version: 26M€ sc version: 2.6 M€ Loss (J) per cycle (0-2T, 4T/s), 1.4 m long test dipoles

9. SIS100 dipole coil design Goal: accurate positioning reduction of point load Result : tube will survive 20 years of operation! Status : mockups were produced mechanical properties tested at 77K Coil support structureFatigue /crack propagation of the Cu-Ni- tube detailed ANSYS model of the coil / conductor (Courtesy of E. Bobrov)

10. 3 full length dipoles / 1 quadrupole under construction 2.1 T dipole, straight at BNG 2.1 T dipole, straight at JINR 1.9 T dipole, curved at BINP 27 T/m quad, 1. 3 m at JINR

11. Cooling magnet –coil and yoke in series, coil first, determines the flow resistance vacuum chamber (reinforced by rips) –by insulated pipes soldered to the rips from BINP

12. operating cycles / loads magnet designed for cycle 2c: 800 msec Injection, 1 sec Pulse (0-2 T, 4 T/s) design limited by hydraulic resistance!! new requirement: triangular cycle, 1 sec → load almost doubled!!! → Consequences for the refrigerator

13. pressure drop Reduction of hydraulic resistance increase tube diameter → filling of aperture, double layer reduce number of turns → high current, single layer

14. Possible redesign of the magnet → increase iron outlet temperature !

15. Cooling system Magnets cooled in parallel Dipole defines the highest hydraulic resistance –→ some magnets (quadrupole, correctors) cryogenically in series Adaptation by orifices question: how much is the variation of flow resistance?