Gas-Controlled Heat Pipes for Accurate Liquid-Vapour Transitions Measurements

At IMGC several gas-controlled heat-pipes have been used to realise liquid-vapour transitions of pure fluids, such as water, potassium, mercury, sodium. A very uniform and stable temperature zone has been realised in all cases, at the millikelvin level. Therefore, very accurate temperature phase transitions measurements are possible, using platinum resistance thermometers. The heat-pipes features and capabilities are summarised, together with a description of the pressure control systems. The most important results achieved using the gas-controlled heat-pipes in primary thermometry and in liquid-vapour phase transition curves measurements are here reported.