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    User name smithg

    Log entry time 15:09:57 on April 25,2003

    Entry number 60087

    keyword=target parked

    So the cryogens were boiled off late this morning after some fan power tests were completed. The new PID has been set up by the target group. At the moment, we are in a PID mode which controls the Loop 2 JT valve by looking at the cold return temperature in the valve box. The goal temperature there is 30K. This is keeping both loops around 30K as well (31-32K). The JT for loop 2 is at around 14%, and we are pulling something like 2-3 g/s from the ESR, which is providing ~16K coolant at the moment. The supply temp. went up considerably during the boil off. The temperature we are pidding on is on channel 2 of the uppermost ITC in the Hall (top of the rack). You can also see it in the cryostat GUI on the right-hand side of the valve box.

    Note that the fans are off, the HPH power supplies are also off. The Loop 3 JT is fully closed. The warm return valve is also closed (was never opened).

    Mike asks that we keep close tabs on the pressures in the system. Currently we have 39 and 42 psia in the H2 and D2 bottles, respectively. We want to look for long steady drops in this pressure that might be the result of a leak, and we want to make sure we don't get even close to going sub-atmospheric. We are still connected to the ballast tanks, so this shouldn't happen. If these pressures drop by more than even a few psi, please page an expert.

    Note also that if you think you need to make a manual change to the JT, in other words if the PID that's been set up breaks at some point, then you will have to come into the hall and adjust the JTs manually. The JT GUI you would normally use from the main tgtgui is disabled while we are running them in PID.