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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
- Chart/MVE Cryogenic Gases Data Book (alternate source)
