Jz. Xu et al., CRYOGENIC TRICK FOR ENHANCED COOLING USING LIQUID-NITROGEN, Journal of vacuum science & technology. A. Vacuum, surfaces, and films, 11(3), 1993, pp. 726-727
The thermal transpiration method has been employed to replace the temp
erature of liquid nitrogen by approximately 12 K. This is done by bubb
ling He (g) through the liquid nitrogen.