Russ Rucinski, PPD/MD/DZero Ops DZero Solenoid What changed? Solenoid was warmed up during this shutdown to fix a vapor cooled current lead leak. Also wanted to de-rime cryogenic piping. –This was the Sixth cool down cycle of it’s life: 1.Factory - Toshiba 2.FNAL Fall ’98 - found bad conductor splice 3.Fall ’99 verify splice repair 4.May 2000 run with VLPC cryostats 5.April 2001 – Run 2 start 6.Fall 2004 – Fix Lead flow leak, de-rime
Russ Rucinski, PPD/MD/DZero Ops DZero Solenoid – Indicators so far Heat load testing – 25 to 30 Watts increased heat load to helium system (over ’98 tests) Req’d helium flow in 1998 was 1.5 g/s now it’s 3.6 g/s. We were running at nominally 3.8 g/s in 11/18 & 11/19 tests No clear cause for extra heat load yet –Coil, Support cylinder, mechanical supports & LN2 shield temperatures look almost same as before. Would need a local hot spot of 8 K!? –Vacuum good – 10E-8 torr –Outer vacuum jackets of control dewar and transfer line (that we can see or measure) shows no temperature depressions.
Russ Rucinski, PPD/MD/DZero Ops DZero Solenoid – To do Continuing to investigate data and try to get to full current. –Run at flowrates > 5.2 g/s. Can go to > 8 g/s. Trying 6.5 g/s at this very moment. –Training? Each quench seems to be at higher current for given polarity. –Calculate local coil temperature for 30 Watt point heat load. –Verify Lhe flow and other instrumentation. –Estimate 2 phase Lhe flow regime in coil given higher heat load & flow, could gas pockets be in cooling pipes? –Soaking periods at current, then smaller steps up in current? –Run LN2 circuit colder? Lhe system change? Would take some time. As of today, we can run at 4600/4750 = 96.8 % of 2 Tesla field in Reverse polarity.