PETS EuCARD. Present status and precision assembly

L. Sánchez, F. Aragón, J. Calero, J.L. Gutiérrez, E. Rodríguez, F. Toral, CIEMAT

26/10/2011

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

Vacuum mini-tank: finished and measured. In tolerances

Present status of the components (ii):

Nominal dimension 466.85 Real 466.98Nominal dimension 462.05 +/-0.05 Real 462.016Nominal 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

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.

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.

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

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

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

0.2Mini 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.

Real tolerances:

0.09

0.180.17

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

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)

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

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

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-ringsVacuum port. CF40. ClosedVacuum port.CF40. Pumping