Flow of He 2 through porous-plug phase separators

A porous-plug is one of the important components for onboard cooling systems which separates the vapor from the liquid helium (He 2). Flow characteristics through porous-plugs and physical situations of He II flow inside plugs are experimentally investigated by examining the temperature distributions inside plugs. It is clarified that He 2 flows ideally, i.e., London's relation is held, in flows through the most part of a plug and turns into vapor phase near the downstream end of it. The flow of the normal fluid component remains laminar in plugs in any experimental conditions. The liquid-vapor phase boundary is formed just at the downstream end and goes down toward the upstream side as the mass flow rate increases. The thermodynamic states of He 2 are also revealed from these flow characteristics.