Thermally induced oscillations of helium in cryogenic apparatus

Pulsating submerged jet and thermally induced oscillations

“…This explanation accounts for the previously known experimental fact [6] of thermally induced oscillations with a steady-state amplitude.…”

“…Experiments on the test apparatus described in [6] have confirmed the fact that, because of the intensification of heat transfer in connection with thermally induced oscillations, the volatility in liquid-helium equipment can exceed the normal value by a factor of 200 in individual tests due to heat inputs via the gas column and heat bridges as well as through the thermal insulation.…”

“…Self-excited oscillations of the helium vapor are easily generated in such tubes and are sustained by a steady flux of thermal energy; they are called thermally induced oscillations [6]. In this case the tube operates like a steam engine, except that there are no valves, the role of which is taken by the vortices and mass transfer near the open end of the tube.…”

“…According to [6], the thermally induced oscillations of helium in nonuniformly heated tubes whose orifices are close to the surface of liquid helium in a tank become particularly strong when the distance from the surface of the liquid to the orifice of the tube is about 2-8 cm. The experiments with the reflector, which functions as a liquid surface in connection with thermally induced oscillations, explain this effect, as well as the considerable attenuation of the oscillations as the tube is brought closer to the liquid-helium tank.…”