Heike R2010-11 R64

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RUN NOVEMBER 2010

First Run with Cu-Stage!

Summary

  • 11.29. : Cryo closed
  • 11.30. : Start filling LN (13:30)
  • 12.01. : Start filling LHe (12:40), Start conditions: TSi=166K, TMag,TOP=155K, TDewar=110K.
  • 12.01. : After 400l of LHe (11:40) dewar is filled and TSi=4.2K.
  • 12.17. : MIX OUT

Tests

We did a lot of test with our new build in devices and connected heat-switches.

  • Thermometry:
    • Test Si-Diode (Model: DT-470-CU): Works great down to approximately 1.1K There is only a small deviation of 0.1K at 4.2K. So we should do some small corrections of the calibration curve.
    • Test PdFe- Susceptibility Thermometer: Doesn't work!
    • Test ET- Susceptibility Thermometer: Works! :)
    • Test Pt-NMR: Works so far. Frozen in a persistent current of 1.5A, but we weren't able to read out the NMR quit well since we didn't know whether the Cu-stage was cold or not.
    • FPD: Read-out doesn't work with the digital Lock-In amplifier ITHACO 3961B due to its too high noise on the analog signal output. Therefore we changed to a analog Lock-In amplifier (ITHACO 393). With this device we are now able to detect all five TC's.
  • Persistent Current Switch:
    • Test PCS of Pt-NMR: Works! (1.5Amp)
    • Test Heat-Switch of Cu-Stage: Doesn't work! :( Seems like the superconducting wire has a small ohmic resistance of a few m. This leads to small heating of some mW and causes the shunting via the 4K-flange!


TO DO

  • Get rid of ground loops.
  • Fixing the superconducting PCS of the thermal link connecting the Cu-stage.
  • Suppress magnetic noise
  • Remove filters in NMR-line.
  • ...