CCDTL 8th technical meeting for production of 7 CCDTL modules for Linac4 (ISTC contract #3888 and #3889), 18-21 June 2012 at BINP

Participants:

BINP Novosibirsk: A. Tribendis (ISTC Projects 3888/89 manager, deputy RF group leader BINP), E. Kenzhebulatov (RF scientist), N. Matyash (senior support engineer), V. Stepanov (technician), Yu Biryuchevsky (design engineer)

VNIITF Snezhinsk: M. Naumenko (ISTC Projects 3888/89 sub-manager, design group leader VNIITF)

CERN Geneva: Frank Gerigk (ISTC Projects 3888/89 coordinator at CERN, RF scientist), Jean-Frederic Fuchs (Linac4 metrology), B. Riffaud (mechanical designer)

Contents

1. Supporting documents in EDMS
2. Technical summary
2.1 Construction status and planning
2.2 Metrology
2.3 Vacuum tests on module 4
2.4 Water cooling scheme
2.5 Other points

1. Supporting documents in EDMS

• Metrology report, JF. Fuchs
• Visit report MME, B. Riffaud
• 3D models and execution drawings of supports (limited access)
• Metrology analysis of Helicoflex joints used for module 4
• Morphology and EDS analysis of Helicoflex joints used for module 4
• Investigation of voids on stem joint surface
• Technical schedule, status June 2012

2. Technical Summary

2.1 Construction status and planning

• 6 (out of 7) modules have been delivered to BINP,
• the packing of the first 2 modules starts next week and preparations are made for delivery in August,
• the first 2 supports will also be shipped (on a separate truck) in August,
• assembly of the first 2 modules on their supports at CERN is foreseen to start on September 17th,
• assembly of the 2nd batch of modules should start in November and finish before the end of the year,
• for the last visit #3889 needs to be extended by 3 quarters (up to May 2013),
• detailed schedule: Technical schedule, status June 2012

2.2 Metrology

A detailed report is in Metrology report, JF. Fuchs. In short: Without a special effort the goal of aligning all cavities and drift tubes around the beam axis within -+ 0.3 mm was achieved!!

2.3 Vacuum tests on module 4

• during vacuum tests on module 4 big leaks were detected on all 3 half tank joints,
• the surfaces were roughened according to the CERN recommendations, while all other joint surfaces were not,
• one theory is that the joints are perfectly centered, since the joints are installed in vertical position, so if the surface marks are indeed circular a non-centered joint may lead to leaks,
• another theory is that there is a problem with this particular batch of joints,
• after the first round of tests two of the half-tank joint surfaces were polished but could not yet be tested due a lack of new joints,
• joint samples will be analysed at CERN,
• all other joints were leak tight with leak rates below the measurement sensitivity,

CERN analysis of joints:

metrology analysis: EDMS 1235932

• the imprinted roughness was measured on both sides of the joint samples and values between Ra 0.2 and Ra 1.33 have been found,
• the recommended surface roughness is 1.6 < Ra < 3.2 um,
• from the shape measurements of the samples it is not clear why one would see 2 imprints on joint contact areas,

morphology analysis: EDMS 1228818

• with these measurements it was confirmed that there are indeed 2 lines of different width and depth present on the joints,
• no Cu traces or other impurities were found on the joints,

preliminary conclusions:

• it is very unlikely that the vacuum leaks were caused by the Cu plating,
• there is no explanation why we see 2 contact areas on these joints instead of one,
• joints from a different batch were sent to BINP to be tested on the same surfaces to see if there is a difference with the joints,
• if these tests reveal the same leaks then the surfaces will be polished again because this seemed to be ok for the tests on module 2,
• new tests will be done at BINP in September,
• if the reasons for the leaks on the module 4 half-tanks cannot be identified the module will be shipped to CERN for further investigation,

2.4 Water cooling scheme

• the 2 small channels (nose, 30 mm2) of each coupling cell shall be connected in parallel, and then in series with the rest of the coupling cell channels (60 mm2),
• the coupling cells can be in series with the drift tubes, which means 2 channels for all drift tubes and coupling cells of one module,
• the tanks will not be cooled in the Linac4 tunnel. Nevertheless, the hoses will be connected in series and we need 2-3 channels per module (the end cell nose channels (50 mm2) are internally connected to the end wall radial channels (95 mm2)),
• the manifolds will be made such that also the tanks can be connected, even if this is not foreseen for Linac4 operation, furthermore the manifolds will have one spare channel,
• the maximum usable pressure drop for the accelerating structures is 5 bars and for each module there is a maximum flow of 5.5 l/min available, the flow is adjustable for each channel,
• Cern will prepare elbow connectors (see photos, which Alexey had sent), and send photos of these connectors to Alexey,
• drawings for draft manifolds will be sent to Benoit for integration in tunnel, (Alexey will include connection for a spare channel)

2.5 Other points

• it was agreed (after the visit) that the plate, which is used to tighten the drift tubes will be zinc plated,
• the supports will have a big number plate with the names of both institutes and the following text: “CCDTL Module No PXACDTL001-BI000001” … “.. PXACDTL007-BI000001”
• the half tanks will be numbered: “PXACDTL001-BI000001, half tank 1” ….
• it was decided that the alignment pins are fixed in the arm plates instead of in the support plates to avoid damage of the arm plates, this will apply for supports 3-7,
• the assembly procedure was discussed and will be finalised by B. Riffaud.
• the tanks will be delivered on their yellow steel frames and the packing of the drift tubes was defined:
  

-- FrankGerigk - 13-Aug-2012