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User name silviu, greg
Log entry time 17:02:04 on December 19,2002
Entry number 54921
keyword=emptier empty target
The target has been warmed up another 10 K and restabilized around 35 K / 19.9 psig. The GH2 density here is 1.75 kg/m^3, about 2.4 % of the liquid in running conditions. The coolant seems to be in a metastable oscillatory mode and holding. The whole thing has been achived by closing the JT valve 1% from the setting for target at 26 K. The cryogroup is not very happy about it, Ganni told us that although we are close to the cold compressor tripping point we didn't reach it yet. We are still on cold return, the coolant flow is about 2 g/s, coolant in is 31.5 K, coolant out is 33.5 K. Coolant back to the refrigerator is 45 K!
The pump is still at 60 Hz.
For overnight target operators: do not touch the JT valve (you may screw up the thd equilibrium irreversibly). The target is in PID regulation with the power limit set at 20 W for now, do not exceed 40 W in this density. Do not put more than 5 uA beam on target (in the thd conditions described above the cooling power is about 30 W if we trust the cold flowmeter, but the heat transfer is very poor).