Abstract: A heat pipe structure, especially for cooling in a spacecraft, is equipped with a main heat pipe and at least one smaller diameter auxiliary heat pipe arranged so that the main and auxiliary pipes are in thermal contact with each other at the evaporator end of the main heat pipe. The condenser end of the auxiliary heat pipe, or pipes, is connected in a heat exchange manner with an auxiliary radiator or heat exchanger which is smaller than and thermally insulated from a main heat exchanger, the latter being in thermal contact with the condenser end of the main heat pipe. The auxiliary heat pipe, or pipes, super cools a bubble trap in the main heat pipe for removing of gas and/or vapor bubbles from the liquid flow path of the main heat pipe.

Abstract: A heat pipe is equipped with a bubble trap. Such bubble trap takes the form of a baffle that restricts the liquid flow in the liquid flow channel of the heat pipe to divide the two-phase flow in the liquid channel into a liquid flow and into a bubble and liquid flow. A cage of wire mesh is positioned downstream of the baffle to entrap the bubbles. In another embodiment the bubble trapping cage is a chamber that extends all the way into the evaporating end of the pipe while the baffle is arranged upstream of such a chamber which is additionally connected through perforations to the liquid flow channels.