1. 1 Progress on the MICE Cooling Channel Magnets Michael A. Green Lawrence Berkeley National Laboratory 28 June 2005

2. 2 3D View of the MICE Cooling Channel AFC Module RFCC Module Coupling Magnet Cryostat Courtesy of S. Yang Oxford University

3. 3 Three Quarter Section View of the MICE Cooling Channel Coupling Coil Focusing Magnet Coil Courtesy of S. Yang Oxford University

4. 4 Half Section View of the MICE Cooling Channel Coupling Coil Focusing Magnet Coil Liquid Hydrogen Absorber 201 MHz RF Cavities Courtesy of S. Yang Oxford University

5. 5 Cooling Channel Magnet Progress The cooling channel consists of three AFC modules and two RFCC modules. This report will discuss the progress made since the last meeting on the focusing magnet and the coupling magnet. Progress on the tracker magnet (detector magnet) will not be presented. This information was presented on June 27th.

6. 6 Focusing Magnet

7. 7 The MICE AFC Module Courtesy of S. Yang Oxford University

8. 8 The Center of the MICE AFC Module Magnet Mandrel Safety Window LH 2 Pipes Liquid Helium Feed Pipe Gas He Pipe Hydrogen Window S/C Coil #1 LH 2 Absorber S/C Coil #2 Coil Cover Plate Courtesy of S. Yang Oxford University

9. 9 The Focusing Magnet Parameters These are the worst cases based on p = 240 MeV/c and b = 420 mm

10. 10 Focusing Magnet Progress Progress has been made on the focusing magnet quench protection system and in the power system for the magnets. The quench simulations show that the focusing magnets can be passively quenched without a formal quench protection system. The three focusing magnets can be connected in series. External diodes and resistors are used to control the voltages across the coils.

11. 11 Focusing Magnet Quench One Magnet & 3 in Series

12. 12 250 A Focusing Magnet Quench Flip Mode & Non-flip Mode

13. 13 Focusing Magnet Mandrel T after a Quench in the Flip Mode Max T = 51.9 K Min T = 4.41 K Quench Time = 4 s I start = 250.8 A  = ~0.80 p = 240 MeV/c  = 420 mm Courtesy of H. Witte Oxford University

14. 14 Focusing Magnet Mandrel T after a Quench in the Non-flip Mode Max T = 41.7 K Min T = 4.69 K Quench Time = 4 s I start = 130.3 A  = ~0.80 p = 240 MeV/c  = 420 mm Courtesy of H. Witte Oxford University

15. 15 Focusing Magnet Mandrel Hot Spot T as a Function of Time Max T = 51.9 K Min T = 4.41 K Quench Time = 4 s I start = 250.8 A  = ~0.80 p = 240 MeV/c  = 420 mm Quench back occurs. Courtesy of H. Witte Oxford University

16. 16 Focusing Magnet Power System

17. 17 Coupling Magnet

18. 18 The MICE RFCC Module Coupling Magnet Cavity RF Coupler Dished Be Window RF Cavity Module Vacuum Vessel Vacuum Pump Magnet Vacuum Vessel Courtesy of S. Yang Oxford University

19. 19 Coupling Magnet Parameters

20. 20 Coupling Magnet Progress Progress has been made on the coupling magnet quench protection system and in the power system for the magnets. The quench simulations show that the coupling magnets can be passively quenched without a formal quench protection system. The two coupling magnets can be connected in series, but it may be better to power the two magnets separately. Cold diodes and resistors are used to control the voltages within the coils.

21. 21 Coupling Magnet Quench One & Two Magnets in Series

22. 22 Coupling Magnet Quench 6061-T6 and 1100-O Mandrels

23. 23 Coupling Magnet Mandrel T after a Quench in the Flip Mode Max T = 83.9 K Min T = 4.21 K Quench Time = 5 s  = ~0.92 p = 240 MeV/c  = 420 mm Courtesy of H. Witte Oxford University

24. 24 Coupling Magnet Mandrel Hot Spot T as a Function of Time Max T = 83.9 K Min T = 4.21 K Quench Time = 5 s  = ~0.92 p = 240 MeV/c  = 420 mm Quench back occurs. Courtesy of H. Witte Oxford University

25. 25 Coupling Magnet Power System

26. 26 Coupling between Magnet Circuits

27. 27 Coupling Coefficients between Coils Magnet Circuit Self Inductance and the Mutual Inductances in the Flip Mode Magnet Circuit Self Inductance and the Mutual Inductance in the Non-flip Mode Courtesy of H. Witte Oxford University

28. 28 Conclusions from the Self and Mutual Inductance Calculations Every magnet circuit in MICE is coupled to every other magnet circuit in MICE. The charging or discharging of one magnet circuit will affect every other magnet circuit, but the power supplies can handle the effect. A quench of one magnet circuit will not drive other magnets normal by changing the currents too much. AC losses induced by a quench do not appear to be a factor, except from mandrel heating.

29. 29 Coupling between Magnet Coil Circuits and other Magnet Mandrels

30. 30 Currents for Various Cases and the Coupling Coefficients Coil Currents for Various Cases where p = 240 MeV/c and  = 420 mm Coil to Mandrel Coupling Coefficients for Various Cases Courtesy of H. Witte Oxford University

31. 31 Heating of the Coupling Mandrel by a Focusing Quench (Flip Mode) Max T = 4.45 K Min T = 4.41 K Quench Time = 4  = ~0.0018 p = 240 MeV/c  = 420 mm A quench of the focusing magnet circuit is unlikely to quench the coupling magnet in the flip mode. Courtesy of H. Witte Oxford University

32. 32 Heating of the Coupling Mandrel by a Focusing Quench (Non-flip Mode) Max T = 4.76 K Min T = 4.69 K Quench Time = 4 s  = ~0.0137 p = 240 MeV/c  = 420 mm A quench of the focusing magnet circuit may quench the coupling magnet in the non-flip mode, at high momenta. Courtesy of H. Witte Oxford University

33. 33 Heating of the Focusing Mandrel by a Coupling Quench (Flip Mode) Max T = 6.30 K Min T = 4.22 K Quench Time = 5 s  = ~0.0813 p = 240 MeV/c  = 420 mm A quench of the coupling magnet circuit is likely to quench the focusing magnet in either mode. Courtesy of H. Witte Oxford University

34. 34 Coupling Coefficients between Magnet Circuits and Various Mandrels The quench of a cooling channel magnet circuit is unlikely to cause a quench of a tracker magnet. A tracker magnet quench won’t quench the channel magnets. Courtesy of H. Witte Oxford University

35. 35 Conclusions from the Magnet Coupling Calculations A quench of a focusing magnet is unlikely to quench any other magnet except the coupling magnet at high muon momenta in the non-flip mode. A quench of a coupling magnet is likely to quench the focusing magnet except at low muon momenta. A coupling magnet quench will not quench the tracking magnet. A quench of the tracker magnet is unlikely to quench any of the other magnets in MICE.

36. 36 Concluding Comments Engineering progress has been made on all of the MICE magnets and their sub-systems. Quench calculations show that the MICE focusing and coupling magnets will quench safely. It is probable that the detector magnets will also quench safely. This will be verified before the next meeting. A coupling magnet quench will cause the focusing magnet to quench, but a quench of the other magnets is unlikely to cause a quench of other magnets in MICE.