56 MHz SRF Cavity Cryostat support system and Shielding C. Pai 1-19-2011.

56 MHz SRF Cavity Cryostat support system and

ShieldingC. Pai

1-19-2011

Configuration of 56 MHz Cryostat

Total Weight estimate of 56 RF cavity cryostat

Niobium + Titanium Vessel: 760 lbTuner Linkage: 100 lbSpace Frame: 400 lbHeat Shield: 150 lbInner Magnetic Shield: 200 lbOuter Magnetic Shield: 250 lbMis. : 240 lb Total Inside cryostat: 2100 lbVacuum Chamber: 1500 lbTuner, 2nd stage 200 lbThermal transition+ 500 lbPiping and Mis. 200 lb

Total in Cryomodule: 4500 lb

Space Frame and Nitronic Rod (Cavity not shown)

Load Path in the 56 MHz Cryostat

Cryostat support

IsolatorActuator

Nitronic Rod Stretch and spring Load

Radial Nitronic rod configuration

1. Length of Rod: Warm: 22.158” Cold shrink: a. Due to Helium tank shrink: + .0085” too long ( 22.1498”) b. Due to Rod shrink: -.0339” Net shrink of rod: +.0085-.0339= -.0254” (D)2. Force induced in the rod with out spring: F=K*D=962 lb

Parts No. AM281413 Quantity: 2 in parallelMaterial: Stainless steelLoad at 3/4 deflection: =540 lb x2=1080 lbK of spring =42,477 lb/in (2 in Parallel)

Stiffness of Rod: 37,909 lb/in (K)

Combined stiffness of system: K=20,031 lb/in

Force induced in the rod: F= 500.7 lb

Add two Disk Springs for Radial support

Axial Nitronic Rod Configuration

1. Length of Rod: Warm: 26.5875” Cold shrink: a. Due to Helium tank shrink: - .0054” ( 26.5929”) b. Due Rod shrink: -.03988” Net shrink of rod: -.0054-.03988= -.04528” (D)2 Force induced in the rod without spring: F=K*D= 1,430 lb

Torsion spring for Nitronic Rod(No Friction Loss for Tuning operation)

Material: Ti-6Al-4VYield strength: 128,000 psiK=840/.02=42,000 lb/in

Stiffness of Rod: 31,593 lb/in (K)

Combined stiffness of System: K=18,117 lb/in

Force induced in the rod: F=K*D= 815 lb (@ 3/5 load)

S=70,123 psi

56 MHz SRF CavityNitronic Rod Support System

Stiffness Analysis

C. Pai1-19-2011

SRF cavity Support, Space Frame with Nitronic Rods

Space Frame

Axial Nitronic Rods

Radial Nitronic Rods

Model, Helium vessel support by Nitronic rods, with disk spring

Loading in Nitronic RodsCase 1. Cold Shrink forceCase 2. Tuning ForceCase 3. Combined Shrink + tuning

Springs are simulated by Combined elastic modulus

E radial: 14.7E6 psiE axial: 16.1E6 psi

Loading in the Nitronic rods

Loading in Nitronic RodsCase 1. Tuning Force, 300 lb Case 2. Shrink to 4.5 KCase 3. Combined Shrink + tuning force

Stress plot, loading: Under tuning force only

Tuning ForceF=300 lbf

Stress in Nitronic rodMax. S: 1313 psiYield Strength: 55,000 psi Annealed

Under tuning force only, deflection plot

Max. deflection at Bracket: .00181”Ratio of stiffness: tuning plate to support system Ratio=.060/.00181=33.1

Under Tuning Force only, Animation

Temperature distribution in the support system

4.5 K

300K

Unit: F

Thermal load only, Stress plot

Stress in Nitronic rodMax S: 34,242 psi, Axial S: 15,638 psi, RadialYield Strength: 55,000 psi Annealed

Thermal load only, Deflection plot

Max. deflection: Far end: -.0799”Near End: .0194”

Fixed bracket: about .001”

Thermal load only, Animation

Both Thermal and force load, Stress plot

Stress in Nitronic rodMax S: 32,939 psi, Axial S: 14,890 psi, RadialYield Strength: 55,000 psi Annealed

Both Thermal and force load, Deflection plot

Max. deflection: Far end: -.0818”Near End: .0175”

Fixed bracket:DY= .0033”

Animation, Both thermal and force load

Space Frame strength Calculation

Model and Loading

Material: SS304Yield strength: 30,000 psi

Gusset

Deflection

Max. ∆ Y=.040”

Max. ∆ Y=.023”

Max stress, S=15,454 psi

Von Mises Stress

Max stress, S=15,454 psiYield strength: 30,000 psi

Eqv Stress

Stress at end plate

Typical bending stress, S=3867 psi

Heat shield, Inner and Outer Magnetic shields

Cross section view of 3 shields

Thermal heat shieldSupported by Vacuum chamber

Inner magnetic shieldInside of Space Frame

Outer magnetic shieldOutside of spaced frame

Space Frame

Thermal Heat Shield (aluminum, .080”) Cooling Tube ID: 0.5” (aluminum extrusion)Thickness for welding, t=.19”Supported by Vacuum chamber

Inner Magnetic shield, Supported at inside of space frameAmumetal, .062”, Room Temperature

Outer Magnetic Shield, Supported at outside of space frameAmumetal, .062”, room temperature

Magnetic shielding effect: (Attenuation) Properties of Amumetal: Mu=60,000, t= .0625” Inner Radius: 18.148 in, Outer Radius: 21.25 in Attenuation of outer shield = 88.8 Attenuation of inner shield=103.8 Total combined Attenuation: 2643. Effect: if stray magnetic field from DX magnet is 10 gauss, the penetrated field to RF cavity is about .00378 gauss.

Magnetic shielding effect: (Attenuation)

Assembled Cryostat