DZero Solenoid status

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DZero Solenoid status

• November 29, 2004

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Recent Quenches Design is 4750 A for 2 tesla
5.2 g/s Lhe flow 11/26
2nd try evening 11/19
1st turn on evening 11/18
Polarity Reverse Forward
Flow decrease
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Overall Running since shutdown
4600 Amps
4500 A
Cryogenic tests
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11/26 quench Quarter tap voltage
Cryogenic tests
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Solenoid Instrumentation
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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 its life
  
• Factory - Toshiba
• FNAL Fall 98 - found bad conductor splice
• Fall 99 verify splice repair
• May 2000 run with VLPC cryostats
• April 2001 Run 2 start
• Fall 2004 Fix Lead flow leak, de-rime

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DZero Solenoid Indicators so far

• Heat load testing 25 to 30 Watts increased heat
  load to helium system (over 98 tests)
• Reqd helium flow in 1998 was 1.5 g/s now its
  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.

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DZero Solenoid To do

• Continuing to investigate data and try to get to
  full current.
• Run at flowrates gt 5.2 g/s. Can go to gt 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.