1. MICE Absorber cryostat Forces and power dissipation - for normal operation and during a magnet quench Elwyn Baynham James Rochford MICE Meeting November 2003

2. Outline Magnet Forces and Quench Issues »Scope –To review the interactions between the magnet system and the H2 absorber units –Magnet system brief overview – focus coils and absorber geometry – separation of modules – not all latest geometry –Magnetic Forces l Static - schematic of forces on coils – internal/external – force management – interaction with absorber l Quench – worst case unbalanced forces – management – interaction with absorber –Quench – present eddy currents,forces,power generated in absorber bodies and windows – for both flip and solenoid mode –Review Impact on absorber design and safety

3. Operational forces 183T228.5T Internal force restraint Suspension -internal axial force restraint External axial force restraint Between cryostats Nett 45T LH Flip mode 240MeV/c,b=43cm Nett 60T Nett 7.9T (Forces for outer most pair of flip coils)

4. Operational forces 146T99T Internal force restraint Suspension -internal axial force restraint External axial force restraint Between cryostats Nett 47.4T LH Solenoid mode 200MeV/c,b=7cm Nett 74.9T Nett 1.2T (Forces for outer most pair of flip coils)

5. Magnet Quench 2d Quench model

6. Magnet Quench Current rundown during a quench for 51H with no protection resistance

7. Magnet Quench Eddy current distribution in holders and windows 2s into a quench whilst operating in 240MeV/C,Beta=43cm mode Eddy current distribution in windows in flip mode

8. Magnet Quench Power dissipated in the inner vessel windows during a quench in 240MeV/C,Beta=43cmm mode

9. Magnet Quench Power dissipated in the inner vessel bodies during a quench in 240MeV/C,Beta=43cmm mode

10. Magnet Quench Force on the inner vessel windows during a quench in 240MeV/C,Beta=43cm mode

11. Magnet Quench Using expression We can estimate the peak stress in the window

12. Magnet Quench Model changed to look at the effect of offsetting a window axially

13. Magnet Quench Force on the inner vessel bodies during a quench in 240MeV/C,Beta=43cm mode with the vessels offset axially by 5mm

14. Magnet Quench Eddy current distribution in holders and windows 2s into a quench whilst operating in solenoid mode -200MeV/C,Beta=7cm Eddy current distribution in windows For Solenoid mode

15. Magnet Quench Power dissipated in the inner vessel windows during a quench for solenoid mode -200MeV/C,Beta=7cm

16. Magnet Quench Power dissipated in the inner vessel bodies during a quench for solenoid mode -200MeV/C,Beta=7cm

17. Magnet Quench Force on the inner vessel windows during a quench for solenoid mode -200MeV/C,Beta=7cm

18. Conclusions –Magnetic Forces l Static – internal/external force management is well understood – no significant interaction with absorber l Quench – coil body forces understood and controlled within magnet cryostat –Quench –eddy current l forces on windows very small cf vacuum/liquid loads l power generated in absorber bodies and windows will not cause significant pressure rise/liquid boil off –Impact on absorber design and safety –– no special design requirements for magnet interactions