56 MHz SRF Cavity Cryostat support system and Shielding C. Pai

Configuration of 56 MHz Cryostat

Total Weight estimate of 56 RF cavity cryostat Niobium + Titanium Vessel: 760 lb Tuner Linkage: 100 lb Space Frame: 400 lb Heat Shield: 150 lb Inner Magnetic Shield: 200 lb Outer Magnetic Shield: 250 lb Mis. : 240 lb Total Inside cryostat: 2100 lb Vacuum Chamber: 1500 lb Tuner, 2 nd stage 200 lb Thermal transition+ 500 lb Piping 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 Isolator Actuator

Nitronic Rod Stretch and spring Load

Radial Nitronic rod configuration 1. Length of Rod: Warm: ” Cold shrink: a. Due to Helium tank shrink: ” too long ( ”) b. Due to Rod shrink: ” Net shrink of rod: = ” (D) 2. Force induced in the rod with out spring: F=K*D=962 lb

Parts No. AM Quantity: 2 in parallel Material: Stainless steel Load at 3/4 deflection: =540 lb x2=1080 lb K 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= lb Add two Disk Springs for Radial support

Axial Nitronic Rod Configuration 1. Length of Rod: Warm: ” Cold shrink: a. Due to Helium tank shrink: ” ( ”) b. Due Rod shrink: ” Net shrink of rod: = ” (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-4V Yield strength: 128,000 psi K=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 Cavity Nitronic Rod Support System Stiffness Analysis C. Pai

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 Rods Case 1. Cold Shrink force Case 2. Tuning Force Case 3. Combined Shrink + tuning Springs are simulated by Combined elastic modulus E radial: 14.7E6 psi E axial: 16.1E6 psi

Loading in the Nitronic rods Loading in Nitronic Rods Case 1. Tuning Force, 300 lb Case 2. Shrink to 4.5 K Case 3. Combined Shrink + tuning force

Stress plot, loading: Under tuning force only Tuning Force F=300 lbf Stress in Nitronic rod Max. S: 1313 psi Yield 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 rod Max S: 34,242 psi, Axial S: 15,638 psi, Radial Yield Strength: 55,000 psi Annealed

Thermal load only, Deflection plot Max. deflection: Far end: ” Near End:.0194” Fixed bracket: about.001”

Thermal load only, Animation

Both Thermal and force load, Stress plot Stress in Nitronic rod Max S: 32,939 psi, Axial S: 14,890 psi, Radial Yield Strength: 55,000 psi Annealed

Both Thermal and force load, Deflection plot Max. deflection: Far end: ” Near End:.0175” Fixed bracket: DY=.0033”

Animation, Both thermal and force load

Space Frame strength Calculation

Model and Loading Material: SS304 Yield 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 psi Yield 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 shield Supported by Vacuum chamber Inner magnetic shield Inside of Space Frame Outer magnetic shield Outside 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 frame Amumetal,.062”, Room Temperature

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

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

Assembled Cryostat