1 RF-Structures Mock-Up FEA Assembly Tooling V. Soldatov, F. Rossi, R. Raatikainen

2 INDEX 1.EBW tooling for PETS Introduction General description Assembly on tooling Transportation EBW process FEA Loading and Boundary Conditions Results Conclusions 2.Brazing tooling for AS Introduction General description Assembly on tooling Brazing process FEA Loading and Boundary Conditions Results Conclusions

3 1.EBW tooling for PETS Introduction General description Assembly on tooling Transportation EBW process FEA Loading and Boundary Conditions Results Conclusions 2.Brazing tooling for AS Introduction General description Assembly on tooling Brazing process FEA Loading and Boundary Conditions Results Conclusions

4 General description Closure assy 1 Mock-up (damped) assembly Minitank (short) assembly Middle connection assy mm mm  202 mm Closure assembly 2 Frictional contact Frictional contact EBW Minitank assembly NO

5 Assembly on tooling Bearing Upper eye-bolt Upper bolt Upper cap cover Lateral eye-bolt Holding- device Lower cap cover Lower bolt Lateral eye-bolt Nut Threaded rod Nut Bearing: allow EBW tooling rotation around its axis, once it is positioned on the EBW machine. Upper cap cover: apply clamping force to PETS unit, once the nut is screwed on the threaded rod. Upper bolt: fix upper cap cover and closure assy 2. Eye-bolts: for lifting and handling. Threaded rod (M16): connection between the upper and the lower cap cover. Lower cap cover: sustain PETS unit during the assembly on the tooling. Lower bolt: fix lower cap cover and closure assy 1. Nut (M16): after it is screwed using a torque spanner, a compressive axial load is applied to PETS units (while the rod has tensile stresses). Holding device: fix axial and angular position between minitanks and adapter disks.

6 Assembly on tooling 1. The second mock-up (damped) assembly is inserted into the middle connection assy 2. Minitank assembly is positioned 3. Closure assy 1 is positioned 4. Threaded rod is inserted and the upper cap cover is positioned

7 Assembly on tooling 6. Clamping force is applied using a torque spanner 5. The holding device is fixed 1st FEM analysis: calculate gap variation in function of the applied load 7. Tack welding

8 Transportation 8. Rotation and transport to the EBW machine. 9. The holding device is removed. Frictional contact Frictional contact EBW 2nd FEM analysis: calculate the clamping force necessary to maintain the contact in the designed area (friction forces between adapter disks and mock-up bars are greater than mock-up bars weight)

9 Clamping force vs. Tightening torque M a [Nmm] = F v ·(0.159·P ·d₂·µ g + 0.5·d Km ·µ k ) = ~ 3·F v [N] CLAMPING FORCE (F v ) CLAMPING FORCE (F v ) TIGHTENING TORQUE (M a ) TIGHTENING TORQUE (M a ) M16 P = thread pitch (2 mm) d 2 = thread diameter (16 mm) µ g = friction coefficient of the thread (0.15) d Km = average diameter of the bolt head (22.16 mm) µ k = friction coefficient of the bolt head (0.15) d km

10 EBW process Welding Bearing Chuck driven by the welding machine Fixed V-support Ground

FEA Aim 1.Calculate the axial force necessary to hold the assembly on the tooling during the EBW process 2.Calculate the deformation involved in the process Hypothesis The problem is considered as a static structural and no dynamical effects were taken into account (e.g. rotational speed rad/s) Model and initial clamping force range for further studies FE-model including: -All copper parts (Cu-OFE) of PETS -St.Steel PETS flanges, minitank and tooling The initial gap of 50 µm is reduced to zero. High deformations of minitanks occur. Friction forces between adapter disks and mock-up bars are lower than mock-up bars weight (the contact is not in the designed area) Maximum 50 kN Minimum 0.3 kN

Clamping force Fixed Gravity 1 st position 2 nd position Fixed (Motor chuck) Loading & Boundary Conditions Bearing condition -The selected ball bearing allows ̴ 10 ̓(0.17°) of rotation -Rotation due to gravity is allowed -Translation d.o.f. is fixed

Results – Axial force of 1 kN Δ gap max ̴1 µm Δ deflection ̴10.5 µm

Results – Axial force of 2.5 kN Δ gap max ̴2 µm Δ deflection ̴10.8 µm Max. Stress 3 MPa

Conclusions On the basis of FEA performed, the selected clamping force is 2.5 kN, which corresponds to a tightening torque of 7.5 Nm According to the results, the reduction of initial flanges gap (50 µm) due to the applied load is negligible. The results show that larger clamping forces do not have significant influence on the transversal deflection of PETS. Anyway, this elastic deflection will be completely recovered once the structure is supported on the designed supports for TM0. The highest stresses occur around the contact area close to the edge inside the adapter disk. For a clamping force of 2.5 kN the maximum value is less than 3 MPa (σ Y = 69 MPa)

16 1.EBW tooling for PETS Introduction General description Assembly on tooling Transportation EBW process FEA Loading and Boundary Conditions Results Conclusions 2.Brazing tooling for AS Introduction General description Brazing process Assembly on tooling FEA Loading and Boundary Conditions Results Conclusions

17 General description Cooling circuit Vacuum flange RF flange Manifold Interconnection flange RF waveguide Accelerating structure Super-accelerating structure Target sphere

18 Brazing process BRAZING (Au/Cu 25/75, 1040 °C) 1.WFM WG cover + WFM WG body (x32=4x8) 2.Waveguide damping interface half 1 + half 2 (x32=4x8) 3.Stack type 1 (x6) 4.Stack type 2 (x1) 5.Stack type 3 (x1) 6.Manifold cover (tank int.) + vacuum tube P1 (x8) 7.Manifold small cover 3 + small cover 3 insert (x32=4x8) TIG WELDING 1.Manifold cover 2 assembly (x8) MACHINING 1.WFM WG brazed (x24=3x8) 2.WG damping interface (x16=2x8) BRAZING (Au/Cu 25/75, 1040 °C) 1.Manifold (hor) assembly (x8=1x8) 2.Hor. manifold (mirrored) assembly (x8=1x8) 3.Vert. manifold assembly (x16=8x2) BRAZING (Au/Cu 35/65, 1020 °C) 1.Structure type 1 (x6) 2.Structure type 2 (x1) 3.Structure type 3 (x1) BRAZING (Au/Cu 50/50, 980 °C) 1.Brazed stack 1 + AS cooling fitting adapters 2.Brazed stack 2 + AS cooling fitting adapters

19 Brazing process 900 °C 1020 °C Temperature history

20 Assembly on tooling Rod Nut Lower plate Lateral support Lateral spring Lateral plate Upper support Upper spring Wedges Lower plate (graphite): support the assembly during alignment operations and brazing cycle. Wedges (ceramic): allow small adjustment of manifolds in the vertical direction. Lateral springs (graphite): apply an horizontal force to the manifolds through the lateral plates and allow thermal expansion of the assembly during the brazing cycle (k=20 N/mm). Lateral supports (stainless steel): support the springs. Upper spring (graphite): apply a vertical force on the manifolds through the upper support and allow thermal expansion of the assembly during the brazing cycle. Rod (stainless steel): connect upper support and lower plate.

21 Assembly on tooling 1. Graphite plate2. Disks stack3. Wedges4. Manifolds 5. Lateral supports, plates and springs 6. Upper support 7. Rod 8. Upper spring and nut

Tooling for the 1 st brazing step FEA A static thermal and structural analysis with a temperature variation from 20 °C to 1020 °C was carried out for the accelerating structure The thermal expansion is constrained only by the springs, which are situated on the opposite sides of the fixed lateral support All the connections were considered ideally frictionless to reduce the computational time Fixed surfaces connected to the lateral support (without springs) Free surfaces constrained by the springs Supported on the ground For the springs a constant stiffness of 20 N/mm was used

Results – thermal expansion x yz Max. in x-direction 4.6 mm Max. in y-direction 7.2 mm Max. in z-direction 5.3 mm

Results – stresses Max. 0.1 MPa Stress due to thermal expansion

On the basis of the FEA the displacements and the stresses due to thermal expansion have been calculated The transversal displacement of the manifolds is approximately 5 mm The axial displacement of the whole structure is approximately 5 mm During the brazing process the calculated stresses are below the copper yield strength at 1020 °C (σ Y = 7.5 MPa) Future work -Transient thermal analysis to model the temperature history -Thermal and structural simulations for the brazing of 4 AS -Structural analysis for the AS intermediate EBW tooling Conclusion