1. PETS EuCARD. Present status and precision assembly L. Sánchez, F. Aragón, J. Calero, J.L. Gutiérrez, E. Rodríguez, F. Toral, CIEMAT 26/10/2011

2. Present status of the components (i): Copper rods: eight copper rods finished, measured and ultrasonic cleaned. In tolerances. Dimensional control reports sent to CERN Pre-assembly of the rods: in vertical position, laying on a granite table using several pieces and rings for alignment. Centering piece for rod assembly

3. Vacuum mini-tank: finished and measured. In tolerances Present status of the components (ii): Nominal dimension 466.85 Real 466.98 Nominal dimension 462.05 +/-0.05 Real 462.016 Nominal dimension 2.45 0/+0.05 Rigth side 2.472mm Left side 2.478mm Nominal diameter 117 -0.1/-0.2 Rigth side 116.89 Left side 116.82 Leak test of the vacuum ports will be made before welding

4. Present status of the components (iii): Couplers: finished, measured and ultrasonic cleaned. Just sent to brazing (ECOR, Italy). All parts within tolerances, although some points out of tolerances. Dimensional control reports are available.

5. Couplers quality control Dimensional control of individual parts. Dimensional control of assembly before and after brazing: Leak testing after brazing:  Cooling circuit.  RF volume. Similar cooling circuit previously tested Pieces for QCF and CF63 Inspection of the brazed joints inside the couplers with a borescope: ensuring no filler overflow.

6. On the copper parts, two HT for stress relieving during machining were carried out (bars, couplers). Conditions: 1 h at 250ºC in air. On the stainless steel parts (X-band Flanges). One HT for stress relieving during machining Conditions: 20 min at 950-1000ºC in air. Heat treatments (HT): On SiC pieces: firing treatment. Conditions: 1h at 1000ºC and vacuum 10 -5 mbar

7. All pieces have been ultrasonic cleaned in a 5% vol. Citranox solution in distilled water at 45-55ºC, rinsed in deminerialised water and alcohol and dried with dry nitrogen. Roughness:  RF surfaces: Ra 0.3  Brazing surfaces Ra 0.8 (Ni plating of SS pieces is not necessary due to the high vacuum of the brazing furnace)  Vacuum tank: Ra 0.8 to improve the pumping  Vacuum tank/ancillary ring joint: Ra 1.6 Surface preparation

8. Joint design The weld joint preparation has been designed for guaranteeing the mechanical and electrical contact between the EBW bars and the couplers Nominal tolerances: 0.05 0.2 Mini tank Additional ring JOINT DESIGN Weld preparation:  Edge joint (Square –lip) for reducing distortion in the rest of the structure.  0.05 Gap. It guarantees the bars/couplers mechanical contact during the pre-assembly before welding.  0.2 Gap. It guarantees that the maximum contraction during welding is 0.4.

9. Real tolerances: 0.09 0.18 0.17 How to control the stress/contraction during welding (i) After accurate measurement of all pieces, the real dimensions of the joint are the following: In the worst case, the contraction during welding will be a bit less than 0.35 mm TIG welding without filler material: lower heat input Partial penetration of the weld joint: lower contraction: Expected contraction lower than 0.35 mm Previous dummy test will be made for adjusting welding parameters and measure the contraction

10. Welding procedure: manual welding.  Spots welds in both joints and subsequent verification of the positioning.  Make short weld beads alternating between both joints and opposite sides of the joints How to control the stress/contraction during welding (ii)

11. Alignment before welding (i) Tolerance requirements: The couplers must be aligned better than 0.05º in radial direction. Vacuum ports must be perpendicular to waveguide ports of the couplers. Before final TIG welding, PETS structure will be supported by an internal bar firmly screwed at both sides Alignment 0.05º. The holes for the support will be used as reference.  In agreement with the 0.05º, maximum deviation of the hole position is 0.064 mm.  Couplers positioning using a dimensional control equipment

12. Alignment before welding (ii) Perpendicularity. The holes or the flat sides of the couplers with the vacuum ports can be used as reference: In the worst case, 0.4 mm of perpendicularity deviation: Perpendicularity tolerance of the vacuum ports in the vacuum tank: 0.2 mm Geometrical tolerances in the couplers side: 0.2 mm Possible alignment between the vacuum ports and the couplers

13. Helium leak test will be carried out after TIG welding Quality control welded joints in the tank Mini-tank: vacuum ports: Welded PETS: Helium leak test Minitank: closed with two caps and o-rings Vacuum port. CF40. Closed Vacuum port.CF40. Pumping