Cryogen usage

Approximate cryogen consumption and service frequency for CSO instruments.

Instrument Precool and
Initial
Subsequent Frequency
LHe LN2 LHe LN2
Bolocam 85 80 25 5 daily
Sharc II 60 110 15 10 2 days
Zspec 160 360 40 50 2 days
230/460 GHz 13 8 4 days
345/650 GHz 13 8 7 days
Barney (345 GHz) 15 25 10 3 daily
850 GHz 13 8 4 days
  • Usage in liters.
  • When the Sharc II low temperature stage is not cycled, 15 l of LHe will last 6 days.
  • Zspec requires daily LN2 service.
  • Additional LN2 for receiver tuning, calibrations, etc.: 3–5 l daily.
  • LHe supplied in 60 l or 100 l dewars, nominal contents in Hilo.
  • Because of depressurization and other losses, LHe dewars arrive at telescope with 80-85% of contents.
  • LHe availability on short notice may be difficult.
  • LN2 supplied in 160 l or 180 l tanks.
  • This spreadsheet provides an approximate estimate of cryogen costs.
    • Change the number of observing nights (in red) for an approximate scaling.
    • The estimate is reasonable for 3 < nights < 15.
    • Costs are subject to change.
    • Final costs will depend on instrument and cryogen delivery schedules.
    • Assumes a Sharc II cycle every night.
    • The heterodyne instruments include 5 l /day of LN2 for tuning and calibration.
    • The sidecab receivers are combined.
    • For the sidecab and 850 GHz receivers, 60 l LHe dewars are used.
    • For the other instruments, 100 l LHe dewars are used.
    • LHe dewar quantization is only approximate.
    • LHe boiloff from the delivery dewars is ignored.
    • For the LHe dewars, rental days = observing nights + 2.
    • Staggered deliveries of LHe are ignored.

Refererence information

cso/instruments/cryogens.txt · Last modified: 2013-05-31 20:34 by admin
 
Recent changes RSS feed Donate Powered by PHP Valid XHTML 1.0 Valid CSS Driven by DokuWiki