MICE Absorber cryostat Forces and power

dissipation -for normal operation and during a

magnet quench

Elwyn Baynham

James RochfordMICE Meeting November 2003

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

Static - schematic of forces on coils – internal/external – force management – interaction with absorber 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

Operational forces

183T 228.5T

Internal force restraint

Suspension -internal axial force restraint

External axial force restraint

Between cryostats

Nett

45T

LH

Flip mode 240MeV/c,b=43cm

Nett

60TNett

7.9T

(Forces for outer most pair of flip coils)

Operational forces

146T 99T

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

74.9TNett

1.2T

(Forces for outer most pair of flip coils)

Magnet Quench

2d Quench model

Magnet Quench

Current rundown during a quench for 51H with no protection resistance

0

0.2

0.4

0.6

0.8

1

0 2 4 6

Time (S)

J/J

max

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

Magnet Quench

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

Windows power dissipation

0

5

10

15

20

25

0.00 1.00 2.00 3.00 4.00

Time (S)

pow

er (

W)

Vacuum window

Absorber window

Magnet Quench

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

Window holder power dissipation

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

0.00 1.00 2.00 3.00 4.00

Time (S)

pow

er (

W)

Vacuum body

Absorber body

Magnet Quench

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

Body f orce on windows

0

50

100

150

200

250

0.00 1.00 2.00 3.00 4.00

Time (S)

Axia

l For

ce (

N)

Vacuum window

Absorber window

Magnet Quench

rJB ..Using expression

We can estimate the peak stress in the window

Magnet Quench

Model changed to look at the effect of offsetting a window axially

Magnet Quench

Force on the inner vessel bodies during a quench in 240MeV/C,Beta=43cm mode with the vessels offset

axially by 5mm

Force on inner vesels off set by 5mm

-600

-400

-200

0

200

400

600

800

0.00 1.00 2.00 3.00 4.00

Time (S)

Axia

l For

ce (

N)

Vacuum body

Absorber body

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

Magnet Quench

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

Windows power dissipation

0

5

10

15

20

25

30

0.00 1.00 2.00 3.00 4.00

Time (S)

pow

er (

W)

Vacuum window

Absorber window

Magnet Quench

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

Window holder power dissipation

0

5000

10000

15000

20000

25000

0.00 1.00 2.00 3.00 4.00

Time (S)

pow

er (

W)

Vacuum body

Absorber body

Magnet Quench

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

Body force on windows

-30

-20

-10

0

10

20

30

40

50

60

0.00 1.00 2.00 3.00 4.00

Time (S)

Axia

l For

ce (

N)

Vacuum window

Absorber window

Conclusions

–Magnetic Forces

Static – internal/external force management is well understood – no significant interaction with absorber

Quench – coil body forces understood and controlled within magnet cryostat

–Quench –eddy current

forces on windows very small cf vacuum/liquid loads

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