Minutes of feedthrough meeting of 19 March, 2001. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Present: PB, Pof, GV, AD, FH, MLenc, MGF, ML, RKK *) Milestones - The two 8-row and four 7-row pincarriers which arrived on 12 March have been cold cycled three times and have passed all leak checks. - The remaing 11 of the 60 ordered `seal ring -to- cryostat chimney' O-rings have arrived. - The Tektronix 3052 scope and its GPIB interface arrived today. - All 7200 nylon spacers to be used when plugging in the vacuum cables have been delivered. *) Pof will arrange that Chris Oram visits our lab sometime during the construction of ft04 for a `mini production review'. *) BNL has found that the use of a small video camera and video monitor is very useful for the visual inspection of pincarriers, checking for small burrs and conductive debris that may result in a short to ground. Pof and Mark will check into the availabilty of small video camera and monitor for use in our lab. *) Due to BNL's experience with conductive debris in the pincarriers resulting in shorts to ground, but considering the possible damage that might result from subjecting our cables to 1000 V HiPot tests, it was agreed that we will do 1000 V HiPot tests on the pincarriers alone, and then use 100 V HiPot tests on the full feedthrough assembly before welding shut. *) Pof will contact Tom Muller to request that more pincarriers be sent, preferable two full sets (eight 7-row plus eight 8-row). *) Pof, PB, and Mark reported on their trip to BNL. Notes from the trip are listed below: Pof's notes from the 13-16 March trip to BNL ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ *) Comparison of feedthrough assembly speed between BNL and UVIC and other notes related to speed and efficiency: -) More people (5 or 6) `on the floor' assembling and testing barrel feedthroughs at BNL, although some of these have other jobs and so are not always present. -) Electrical and Vacuum testing is much faster at BNL. The cold electrical tests are strictly TDR based, which can be done in about one hour per feedthrough. The feedthroughs can be installed into the cold test station by one person, and the entire cold test (vacuum and electrical) can be completed in 24 - 36 hours. -) BNL uses very short (~15 cm) pigtail shorting loops, and have sufficient numbers of these that they get installed early in the assembly procedure and are left on until all electrical tests are completed. -) BNL does not use jackscrews to install their test leads, but have designed a handle for the ATI connector which allows the test leads to be plugged in and removed easily. The non-use of jackscrews also makes it easier to detect a bent pin while plugging in the connector. -) When installing the vacuum cables, BNL does not `bottom out' the vacuum cable jackscrews until an entire pincarrier is filled. This makes it easier to install the vacuum cables when the plastic cases may be slightly over tolerance in width. -) The UVIC assemly area is generally cleaner than the BNL assembly area. *) Pincarrier preparation and inspection notes: -) BNL cleans all pincarriers in acetone; no rinse to remove any residues from acetone bath. -) BNL visually inspects all pincarriers before use. They have a number of tools for this, ranging from standard visors to video camera setups with backlighting to shine through the glass beads. The visual inspections pick out potential problems such as whiskers left over from deburring, conductive debris left at the base of the pins, and the minute wire strands used in the pincarrier manufacture that sometimes get left wrapped around a pin. -) Some pins have been found that are not centred in their sockets. -) Some pincarriers have been found with gold plating at the weld lip. *) Pincarrier production issues: -) Glasseal is presently producing nine pincarriers per week, but is expected now (ie, mid March) to increase this rate to 20 per week (we'll believe it when we see it...). -) BNL can handle 10 pincarriers per week (six feedthroughs per month). -) Pof communicated to Tom Muller that UVIC's feedthrough production rate is not as high as BNL's. In the interest of optimizing the overall ATLAS construction schedule, it is important that BNL be prepared to `share the pain' and that UVIC receive at least some pincarriers sooner rather that later. *) HiPot and TDR test issues (all HiPot tests are done at 1000 Volts): -) All pigtails and vacuum cables are HiPot tested individually before installation into the feedthrough. The main purpose of the HiPot tests on the vacuum cables is to detect the defect which allows adjacent lines to short. It is unclear to me why one would subject the pigtails to a HiPot test at this point. TDR tests are also done on the individual cables. -) All pigtails are HiPot tested after they are inserted into the cold flange. The main purpose of this is to check for conductive debris left in the pincarrier. -) After installation of the vacuum cables, but before welding, all pigtails and vacuum cables subjected to one last HiPot test. This test is also done primarily to check for conductive debris left in the pincarrier. There are *no* HiPot tests done after welding. -) After welding, the feedthroughs are TDR tested warm, then cold, and then warm again. Note that, even though the pigtails are looped all slots are tested so that each pair of lines is tested from both directions. *) HiPot test statistics: -) 1005 pigtails tested, three cycles each, five cables damaged. The damage has always been at the micro-D, starting with a dielectric failure, then a dead short. No pigtail failures have been detected aside from the damage done from the test itself. -) One test lead pigtail has been subjected to more than 600 HiPot cycles with no failure, but that cable has no micro-D. -) 2200 vacuum cables tested, three cycles each, no cables damaged. The rate of HiPot failures that have been found for the vacuum cables when tested individually is approximately 1 in 30. (The exact failure rate is unknown, and may be as high as 1 in 20 or as low as 1 in 50.) -) Ten feedthrough assemblies have been HiPot tested, with a failure rate ranging from two to three per flange side. These failures have been mostly due to conductive debris in the pincarrier, and are easily `repaired' by cleaning. *) Pedestal issues: -) The baseplane lifts off (hinged at one end?) to allow pluggin in of the warm cables. -) The vacuum plumbing will be installed before the warm cables. -) There appears ample room for the use of the `stiff' HEC LV warm cables. -) The warm cables used in the BNL mockup are ~28 cm face-to-face. The distance from the warm flange to the baseplane was (crudely) measured to be ~13 cm. Note that the baseplane slots for the rear (smaller local z) slots are offset toward smaller local z relative to the warm flange slots by about 10 cm. *) Micro-D issues: -) BNL has broken three micro-D's during testing and assembly, although this might be due to BNL's not using the micro-D jackscrews to plug them in during testing. Bob Hackenburg prefers not to subject the micro-D's to any more plugins than absolutely necessary, considering them to be a `one plugin' device only. Note that BNL's TDR electrical tests at CERN require plugins only at the warm flange. *) Other issues: -) BNL has been applying lock-tight to the pigtail jackscrews, however no checks have been made that lock-tight will not poison the Argon. BNL trip - Mark's notes & misc. ramblings (proper grammar not guaranteed). ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ *) Shipping container comments The BNL shipping container is quite stout. To remove the FT from the BNL box requires the unscrewing of a top lid and four individual restraint ribs. The shipping container design is not conducive for any testing while the FT is inside it unless the ends are removed from the box. I am not sure if these ends where not attached in a permanent fashion making their removal awkward. The BNL container currently is not intended to have any kind plastic wrap or desiccant. Cleanliness of this design at moment is not as good as the UVIC version. Basic consensus among the UVIC contingent present at BNL and also one BNL tech, is that the UVIC shipping container is a preferable design. An idea that can be used from the BNL design is the use of external handles instead of cut out slots in the current UVIC FT shipping container. *) Pedestal stuff There were two pedestals on a mockup. Unfortunately they were both still non-production prototypes. The basics were there however. After consultation with production drawings it was confirmed that the UVIC heater will fit in the pedestal FT cutout. BNL will be receiving 4 pre-production pedestals for evaluation in the very near future. There was very loose talk that we at UVIC might be able to get our paws on one for evaluation here at UVIC. It was discovered that the fuse circuit board is (until further notice) on the wrong side of the UVIC prototype heater. This will have to be checked and rechecked to be confident beyond a shadow of a doubt. The length of wires and routing of the power wires and RTD wires looks to be straight forward and can be finalized with the procurement of production pedestal drawings and filter box drawings. The plumbing for the pedestal is still not finalized. Ken Sexton was still in the process of building a production prototype with a flexible tube and VAT valve that we saw at their workshop. *) Filter box issues The first day and a half of our visit to BNL was consumed with observing, photographing and discussing various FT production issues. Unfortunately we were not able to make contact with Don Makoviecki on our final half day at BNL to discuss some of the filter box issues. Although it would have been best to speak with Don face to face I believe it is quite possible to finalize our power and RTD connections with a flurry of emails. *) Pin carrier odds & sods I sized up a big collection of reject pin carriers in various stages of machining for possible use as cool paperweights. Ken showed me a test plug to check the break over voltage between the pins and pin carrier body. This test had a plug that electrically connected all the pins together. I can't remember exactly what he did next, but I assume that a voltage was then applied between the pins and body to check for break over, or a ohm meter was used to measure any direct shorts between pins and body. Pof is looking to do something similar to our pin carriers possibly using the Cirrus tester. BNL washes the pin carriers in acetone. BNL also uses compressed air to blow out and debris or reluctant bits that may be clinging to the inside of the pin carrier. A generic home use (approx. 2hp) compressor supplies this compressed air with a typical water/oil/dust trap regulator assembly. Should UVIC employ compressed air, I would recommend an additional air drying canister (desiccant filled) for a 100% dry air supply. We observed a video inspection station for looking over pin carriers, looking for any kind of machining flaws like metal debris, shavings, whiskers or just plain dirt. A small metal pick was used to probe or manipulate any garbage that was found in the vicinity of a pin base. A compressed air nozzle was in close proximity to dispatch any flaw that was loosened by probing. It also was possible to see a small unplated band around each pin where wire wrap was affixed to each individual pin. The video inspection looks to be a useful routine to implement. However it seems to me it would be useful to have a work table that has a guide that would only allow a pure left/right motion. At higher magnifications, it is hard to manipulate the pin carrier without making a big shaky motions that hamper inspection. There has been mention of possibly motorizing this table also. We may also consider making this movable table big enough to inspect pin carriers when they have been welded into flanges. A convenient and rigid vertical adjustment on the camera would be handy too for focussing purposes. The magnification of the camera was varied by inserting or removing a spacer between the camera and its lens. BNL has a nice metal, tight fitting pin straightening/inspection device. This device was demonstrated on a pin carrier. It was snug, but did not bend pins back perfectly back on axis, though it would work if pins were any more out of alignment than what was shown to us. Without seeing if the tendency of production pin carriers having large amounts of crooked pins, I am not sure we need this item. *) Micro-D conversations I was not too in on these discussions, but a few points did seem to sink in. Some of the insulation of the Micro-D's was chipped when the plug was mildly mishandled. By mishandled it is meant that the plug was possibly inserted at too much of an angle rather than somewhat parallel. The pins on the Micro-D appear to be compressed wire, possibly made from the core material (strands) of the wire. These tiny "pins" are regarded to be fragile if abused and any insertions should be straight on. *) BNL in general The place is quite spread out over many square miles. Guards at the entrance had a big ass gun hanging on the wall if people misbehaved. Tons of deer hang around the site munching on young trees and brown grass. Also there were flying rats (geese) and wild turkeys hanging around the premises. Cafeteria is an interesting architectural exercise. It is concrete construction in a 60's futuristic type style, open and multi faceted walls, perpendiculars surfaces are scarce. Food is affordable and palatable. Low level offices are spread out around the property. To get from one end to another, or from office to workshop one would actually use a vehicle. The RHIC accelerator is very fresh looking and boasts the largest Helium refrigeration/compressor in the world for their super-conducting magnets. BNL also has its own reactor and at one time either stored or made their own fissionable material. Tom gave us a short video describing RHIC in a generally understandable manner for us simple folk eh. For those interested in seeing it, it is in room 203 for now until I find a more appropriate spot for it. Agenda for next week: ^^^^^^^^^^^^^^^^^^^^^ - Milestones - Pincarrier HiPot tests - Pincarrier video inspection setup - Plans for ft03 construction - AOB