A glass or metal double-walled flask for holding a liquid without much loss or gain of heat; a vacuum bottle or thermos. Generally used for scientific purposes and in particular for cryogenic work
A vacuum flask; a vessel which keeps its contents hotter or cooler than their environment without the need to modify the pressure, by interposing an evacuated region to provide thermal insulation between the contents and the environment
A double-walled vessel for holding liquid Nitrogen (LN2) used to cool the detector chip RÖNTEC UHV dewars are constructed with multiple walls and vacuum chambers to provide excellent thermal isolation and low LN2 boil off rates
CCDs operate at their optimum when cold Dewars are made for just that purpose Astronomers want only optimized equipment to collect the most light possible from distant objects For the CCD to run at its best, it needs to be cold--as cold as liquid nitrogen (77 Kelvin/-321°F/-196°C) CCDs generate electrons just from being warm (by warm, we mean room temperature), without exposure to light Also, the chamber where the CCD resides needs to be under vacuum The CCD will be below the freezing point of water, once cooled Water vapor in the atmosphere would condense on the surface of the device (frost!), if the atmospheric air was not removed, and affect the images