โ Scribed by B.K. Jones
No coin nor oath required. For personal study only.
using 0.05 mm diameter, 500 cm long PE ShOK constantan current leads, led out through the liquid helium bath, is shown as curve 3. In this case, the heat flow in the stationary state was ,~ 10 -14 W, while the Joule heating dissipated in the leads exceeded this by many orders of magnitude (N 10-6 W). From the fact that in the absence of charcoal, the thermometer with constantan leads, led through the liquid helium bath, did not cool below ,-~ 60 K, one can conclude that in the presence of the adsorbent, it was at a higher temperature than the adsorbent. Curve 4 refers to an experiment with a very overheated thermometer, since the 0.5 diameter, 500 cm long Pe ShOK constantan leads went directly to room temperature. In spite of the large amount of heat conducted to the thermometer in these conditions, the final temperature recorded by the thermometer was 9.4 K, which points to the appreciable influence of the temperature of the charcoal on the thermometer.
By comparing the results of the two series of experiments (curves 1-2 and 3-4), we can conclude that the true cooling curve lies between curves 2 and 3, that is, the end temperature of the adsorbent is close to the temperature of the surrounding bath, but reaches it after 30-40 hours.
From these results it follows that in normal experiments to achieve temperatures below 1 K, the adsorbent is first at a temperature which is far from corresponding to the bath temperature, since the time from the start of cooling until adsorption starts is not more than 30-40 rain. In the subsequent adsorption of helium vapour from an initial temperature of 1.5 K (a pressure of 3.6 torr for "He and 50.8 tort for 3He), two processes take place: (1) the rapid cooling of the adsorbent because of the heat conductivity of the gas, and (2) its heating up by the heat of adsorption. This leads to an equilibrium
๐ SIMILAR VOLUMES