A tube furnace is a type of furnace that heats materials inside a tube-shaped cavity. In some cases, it may be necessary to perform heating in a vacuum environment. A vacuum tube furnace is typically designed to create and maintain a low-pressure, or vacuum, environment within the tube cavity during heating.

The vacuum function of a tube furnace is important because it can help to prevent oxidation, contamination, and other types of chemical reactions that may occur when materials are heated in the presence of air or other gases. By creating a vacuum, the furnace can remove oxygen and other reactive gases from the environment, which can help to minimize unwanted reactions and ensure that the material being heated remains pure.

To create a vacuum in a tube furnace, the furnace is typically equipped with a vacuum pump and a vacuum gauge. The vacuum pump is used to remove air and other gases from the tube cavity, while the vacuum gauge is used to monitor the level of vacuum inside the furnace. Once the desired level of vacuum has been achieved, the heating process can begin.