Background

The ESI CCD dewar is cooled by liquid nitrogen (LN) cryogen in order to maintain the detectors at their optimal operating temperateres of -120 C. This webpage describes adopted practices in achieving accepable dewar vacuum, timescale for cooling the dewar after a warm fill and for warming the dewar when cryogen is exhausted.

Acceptable Vacuum

TBD

Cooldown Curve

The following plot shows the behavior of the dewar temperature following a warm fill. The dewar can typically achieve the standard operating temperature within about 2.5 hours after the LN warm fill.

DEIMOS cooling plot Click to enlarge

Warmup Curve

TBD