Minutes of feedthrough meeting of 14 August, 2000. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Present: GV, Pof, PB, MLenc, AD, TH *) Milestones: - 100 Vacuum Cables arrived on 1 August. Visual inspections were completed today (14 Aug). One cable was failed due to a bent springclip; all others passed. - Greg and Aaron cleaned 20 warm flanges, 20 cold flanges, and 12 bellows at the TRIUMF ultrsonic bath on 9 and 10 August. The cleaning went quicker than expected, and they were finished by 2:00 on 10 August. A second support bar (for holding the pieces while being dipped in the bath) would further speed the job. *) Aaron has finished writing the detailed Cold Test procedures. We expect to start the cold electrical and leak tests on Wednesday or Thursday this week. A further set of thermal tests will also be performed. *) Alberto Desirelli notified Terry by email that the latest set of weld samples shipped to CERN on 5 July 00 are not acceptable, but failed to elaborate on what sort of problems they found. This has come as a complete and unwelcomed surprise. Terry will try to get further information from TIS. Terry wonders if TIS might be trying to manouver us into providing a weld sample in a geometry closer to that of the feedthroughs, ie, cylindrical rather than flat. TIS has in the past made suggestions that they cut open our first production feedthrough for inspection... *) Terry heard from Tom Muller of BNL regarding the `leaky pincarrier' problems. Glasseal is now suggesting that the problems they have encountered might be due to the Timpken steel. As a test, they will produce ten pincarriers out of standard 304L steel (ie, not low inclusion) to see if the problems persist. Tom Muller, Terry, and Michel will meet Bill Hubbard of Glasseal at HCC in California next week to investigate the problem further. In the meantime, BNL is looking into the possibility of aquiring more CERN low inclusion steel in case the Timken steel does turn out to be at the root of the problem. Even is the problem is solved immediately, we should probably not count on another batch of pincarriers until mid October at the earliest... *) The heater power supplies proposed by CERN operated at a maximum of 3 amps and 48 Volts, providing 144 watts (in our worst case scenario of 1.5 bar in the bellows, we estimate that we would require 145 watts). The effective resistance of our heaters (six 50 ohm resistors in parallel) is 8.33 ohms, which would deliver only 75 watts of power at the maximum 3 amp current. For the record, BNL's heaters are 12.5 ohms, leading to a maximum power of 113 watts. One possible solution is to use 100 ohm resistors (same footprint as the 50 ohm resistors) in place of the 50 ohm resistors, giving us a maximum of 138 watts of heating power at 48 volts. Another solution would be to use 75 ohm resistors, which would give us an equivalent of 12.5 ohms with the six resistors in parallel, equivalent to BNL's heaters. More on this topic next week... Agenda for next week: ^^^^^^^^^^^^^^^^^^^^^ - Milestones - Plans for HCC visit - Bellows news - Heater update - Cold Test report - AOB