56 mhz srf cavity thermal analysis and vacuum chamber strength c. pai 1-19-2011
TRANSCRIPT
56 MHz SRF Cavity Thermal Analysis
and Vacuum Chamber Strength
C. Pai1-19-2011
Thermal Analysis of Transition adaptor
Purpose of the calculation1. Verify the function of the thermal transition. The thermal transition
is a bridge to connect the superconducting cavity to the room temperature cryostat. It should minimize the heat load into SRF cavity. This thermal transition has no cooling tube attached.
2. Calculate the total heat load input from room temperature to the superconducting Cavity from 3 sources.
2.1 Conduction from cryostat to the cavity. 2.2 Radiation heat from room temperature beam pipe into cavity
space.This heat is conservatively assumed that half of the radiation heat is deposited
in the neck of the tuner plate. 2.3 Heat generated by field emission current in the cavity gap.The field emission heat is when gap temperature is kept at 6.5 K.
3. Calculate the maximum temperature in the tuner plate.
4. Calculate the heat load in the Helium bath and Cooling channel.
Thermal Transition of 56 MHz cryomodule
Thermal Transition
SRF Cavity
Cryostat
Tuning plate Connecting yoke
ANSYS Model of Thermal transition with tuner plate for heat transfer analysis
Tuning Plate
Nb Formed Head
Double welded bellow
Formed bellow
End flange Welded to vacuum chamber
Tuner yoke with Helium channel embedded Beam
pipe Flange
Cooling Channel
Note: The Tuner yoke has liquid Helium channel embedded (Cold anchor)
Tuner Yoke with Helium flow Channel
Case 1, Heat leak from cryostat only, No radiation and field emission heat in the gap
Helium channel , at 4.5 K
Brass threaded rod
Room temperature
Helium Temperature4.5 K
Result of case 1, Overall Temperature distribution Heat input from cryostat only, No radiation and field emission heat in the gap
300 K
Vacuum chamber: Q= +.294 W
Pipe flange:Q: + .0191 W
Helium headQ: -.298 W
Tuner RF body , cooling channel Q: -.005 W
Yoke anchorQ: -.010 W
TotalQ: +.313 WQ: -.313 W
4.5 K
4.537 K
4.5 K
Result of case 1, Tuner Neck temperature Heat input from cryostat only, No radiation and no field emission heat in the gap
4.5 K
4.87 K
Result of case 1, Yoke and tuner neck Temperature, Heat input from cryostat only, No radiation and field emission heat in the gap
Case 2, Heat input from cryostat plus radiation heat. No field emission heat in the gap
Radiation heat: half of 3.38 watt (in half model) deposited in the neck of tuner plate
Room temperature
300 K
Vacuum chamber: Q= +.294 W
Pipe flange:Q: + .0192 W
Helium headQ: -.299 W
Tuner RF body , cooling channel Q: -.815 W
Yoke anchorQ: -.0489 W
Radiation heatQ: +.85 W
TotalQ: +1.163 WQ: -1.163 W
4.5K
Result of case 2, Overall Temperature distribution Heat input from cryostat plus radiation. No field emission heat in the gap
4.5K
6.84K
Result of case 2, Tuner Yoke and neck temperature, Heat input from cryostat plus radiation. No filament current heat in the gap
6.30K
From Field emission heat, T= 6.5 K
Case 3, Heat input from cryostat, plus radiation and Field emission heat in the gap
Radiation heat: half of 3.38 watt (in half model) deposited in the neck of tuner plate
Room temperature
300 K
Vacuum chamber: Q= +.293 W
Pipe flange:Q: + .0192 W
Helium headQ: -.299 W
Tuner RF body , cooling channel Q: -7.494 W
Yoke anchorQ: -.0696 W
Radiation heatQ: +.85 W
TotalQ: +7.862 WQ: -7.764 W
4.5K
Field emission heat:Q: +6.7 W
Result of case 3, Overall Temperature distribution Heat input from cryostat plus radiation and field emission heat in the gap
4.5K
7.73K
6.5 KAssumed by filed emission heat
Result of case 3, Tuner Yoke and neck temperature, Heat input from cryostat plus radiation and filed emission heat in the gap
7.0K
Summary of results (Note number is for whole model)Case 1: Heat leak: From cryostat only, No radiation or field emission heat in the gap Heat load in the system: Total: .626 W From: Cryostat, +.626 W To: Helium Bath, -.616 W Tuner plate and cooling channel, -.01 W Maximum temperature: (Helium at 4.5 K) At end tip of Tuner plate : 4.537 K At Tuner Yoke: 4.87 K
Case 2: Heat input: From cryostat plus Radiation. No field emission heat in the gap Heat load in the system: Total: 2.326 W From: Cryostat,+ .626 W Radiation, +1.70W (Conservatively, in the neck of tuner plate) To: Helium Bath: -.695 W Tuner plate and cooling channel: -1.63 W Maximum temperature: (Helium at 4.5 K) At end tip of Tuner plate : 6.84 K, most of the neck is below 6.3 K At Tuner Yoke: 6.84 K
Summary of results (Continue)
Case 3: Heat input: Heat input from cryostat plus radiation and field emission heat in the gap Heat load in the system: Total: 15.724 W From: Cryostat, +.624 W Radiation: +1.7 W Field emission heat : + 13.4 W (when Gap Max. T at 6.5 K) To: Helium Bath, -.737 W Tuner plate and cooling channel, -14.988 W Maximum temperature: (Helium at 4.5 K) At end tip of Tuner plate : 7.73K, At Cavity Gap: 6.50 K At Tuner Yoke: 7.73K
Model, 56 MHz SRF Cavity Vacuum chamber
Thickness:Cylinder: 5/16”Head: .375”Material: SS304Yield strength: 30,000 psi
Displacement, in cylindrical coordinate, radialUnder Vacuum P=14.7 psi
Cylindrical Coordinate
Max : .0216”
Equivalent Stress, cylinder shell
Max. Equivalent stress”S=4,600 psi
Yield Strength: 30,000 psiAllowable:Membrane: 20,000 psiBending: 30,000 psi
Equivalent Stress, cylinder shell
Max. Equivalent stress”S=3,971 psi
Yield Strength: 30,000 psiAllowable:Membrane: 20,000 psiBending: 30,000 psi
Equivalent Stress, 3 port Head
Max. Equivalent stress”S=7,680, psi
Yield Strength: 30,000 psiAllowable:Membrane: 20,000 psiBending: 30,000 psi
Equivalent Stress, 4 port Head Max. Equivalent stress”S=5,345 psi
Yield Strength: 30,000 psiAllowable:Membrane: 20,000 psiBending: 30,000 psi
Buckling Multiplier in cylinder, M=12.39,> 2.5 (Cylinder)
P=14.7 psi
ASME Viii-2Required Multiplier for Cylinder: 2.5
Buckling Multiplier in Head, M=91.5,>16.13 (head)
ASME Viii-2Required Multiplier for head: 16.13
Cost Estimate of Cryomodule AssemblyMach.
Mat. Cost Estimate Hr Mach. Costhr
1 Vacuum chamber $78,650 730 $80,3002 Thermal transition $5,284 136 $14,9603 Outer Magnetic shield $19,669 100 $11,0004 Space frame $19,698 76 $8,3605 Outer Super insulation $2,5805 Thermal heat shield $1,735 104 $11,4406 Middle Super insulation $2,7207 Inner Magnetic shield $12,176 160 $17,6008 Inner super insulation $1,8759 Radial Nitrionic Rod 8 sets $960 48 $5,280
10 Axial Nitronic Rod, 8 sets $960 48 $5,28011 Nuts, and bolts, etc $6,800 56 $6,16012 Welding, cryo and vacuum 120 $13,20013 RF-Shielded Gate Valves (2) $78,00014 Misc. Components $18,530
$249,637 1578 $173,580$ hr $
Total Mat. Mach.