Minutes of feedthrough meeting of 10 April, 2000. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Present: MGF, GV, AD, Pof, MLenc, RL, JL, TH, RKK, PB *) Milestones: - The jig to hold the flanges during electrosonic cleaning is finished. - The jig to hold the gland during welding is finished. - The electrical test equipment hardware is now working, the last problem regarding simultaneous running of Phred and Phreda finally being solved. Work continues on finetuning the software. - Full `production mode' continuity (Cirris) and crosstalk tests were done on FT-1 installed in the cold station, but under ambient conditions. The total time required to complete the tests (with one person only) was approximately 3 hrs. *) Terry is to check the delivery schedule for the 7-row pincarriers. *) The two weld samples sent last week to CERN have arrived. *) Terry has ordered the ferrite scope. *) Aboud has agreed to purchase the four pincarriers offered to him for a total price of $4293.14. *) The first shipment of 350 Vacuum cables is expected to be shipped to us this week. *) The bolt rings have been returned to Sicom for alodine treatment. *) Many of the 51 ambient flanges received last week were slightly undertolerance in one axis of the pincarrier slots, on the B side only. Our pincarriers, however, will fit in the slots if the flange is preheated with a heat gun. All of the 51 ambient flanges have been fully processed. *) AD is working on a prototype aluminum flange heater. This will be installed on FT-1 to evaluate during the cold tests this week. *) Roy received the sample thermal contact sheets. The price is negligible, about US$50 per sq yard. Terry will order two types, one for between the heater plate and the ambient flange, and the other for between the resistors and the heater plate. *) Terry received the written report from Bacon Donaldson regarding the steel flaw. The flaw is an inclusion, about 7mm long, presumably resulting from the deoxidizing agents. *) Items still required to start feedthrough construction: - bellows - Roy will check on expected delivery date. - vacuum cables - expected any time now. - cold flanges - expected end of April. - some pigtails (slots 1,14,15) - MGF will contact Orsay. - funnel bases - expected 17 April, then to be sent to SM. - glands (T-pieces) - expected 1 May. *) Paul B has returned from his Leak Checker Maintenance course in San Jose. Our HLT160 leak checker is now repaired and will be shipped back next week. A decision has been made to purchase a second leak checker, which is more robust and simpler to repair (the HLT270) at a cost of US$20,000. Paul's notes are reproduced below. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Begin Paul Birney's notes ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Our HLT 160 Leak checker This leak checker in general. The two most common problems with the HLT 160 are:- 1) Dirt in the valve block - ie. A leaky valve 2) Contaminated grid - ie. Reduced sensitivity of the analyzer Rebuilding the valve block is relatively straightforward and does not require many parts, but this does take time to dismantle, clean and reassemble. There is also a possibility that one or more of the valves can leak at a valve seat or at a bonnet seal. Rebuilding the analyzer is more difficult, it requires several expensive parts, and is extremely difficult to align. If the alignment of the filament is not set perfectly the leak checker may not change smoothly between the high and low ranges, may not detect He at the low leak ranges, or may not even see helium at all. Our Leak Checker It looks like there were two problems with our leak checker. Contamination on the grid causing reduced sensitivity and calibration problems and a bad main processor board causing the error 15 on startup and resetting to default values (including 50 Hz). This bad processor board may have affected operation of the leak checker in an unknown way. In addition the lubrication felt for the bearings in the turbo molecular pump was changed and the valve block was rebuilt. Our leak checker looked to be in very good shape, I can not think of any reason why the main processor board gave trouble. I understand that the grid screen needs to be changed along with the filament every four to five years as a result of "stuff" coming off of the filament and landing on the grid. Why our grid became contaminated after only one year is unknown. The location of the analyzer at the top of the turbo pump normally keeps contamination away from the analyzer. (Normally only Helium back streams through the turbo pump). Option of Trading In our leak checker - (depending on cost??) The HLT 160 leak checker is no longer in production, Pfeiffer now sells a different leak checker with a totally different analyzer. This analyzer is supposed to be harder to contaminate, go longer between rebuilds and much easier and cheaper to rebuild when it requires it. It also will test chambers with a pressure as high as 25 mBars, and it is clamed to detect leaks as low as 5 x 10-12 mBar l / s. It has a liquid crystal display which has several display modes including a leak rate vs. time graph. The HLT 270 comes with a dry diaphragm pump (or a scroll pump) for a completely oil free system. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ End Paul Birney's notes ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Agenda for next week: ^^^^^^^^^^^^^^^^^^^^^ - Milestones - 7-row pincarrier delivery schedule (TH) - Expected delivery date for bellows (RL) - Cold tests / heater performance - Missing pigtails/labels - AOB