Liquid Helium Level Indicator
Original Publication Date: 1981-Jan-01
Included in the Prior Art Database: 2005-Feb-10
In a closed Dewar vessel partly filled with liquid helium (He), a manometer reads the He vapor differential pressure between the space above the level and the He vapor pressure in a small vertical glass pipe submerged to nearly the bottom of the Dewar. In this sensor tube the liquid He is driven out by evaporating with the aid of small amounts of heat introduced by the thin copper wire extending inside along the tube.