New leak element using anodic aluminum oxide

• A new leak element is developed using anodic aluminum oxide (AAO).
• The effective area of AAO is controlled by shadow coating technique.
• The conductance of the leak element is measured based on difference method.
• The gas flow through the leak element is molecular flow range up to 105 Pa.

A leak element has been developed based on anodic aluminum oxide (AAO) by means of the shadow coating technique. The gas flow through the leak element can exhibit the molecular flow in the pressure range from high vacuum to atmospheric pressure for helium and other heavy gases, since the AAO is made of multi tubes with the diameter of about 70 nm. The shadow coating technique could achieve a specific number of tubes on AAO to satisfy the conductance required for vacuum applications. Some key characteristics of molecular flow are demonstrated according to the conductance measurement using difference method. The flow rate of any other test gases introduced in to the vacuum chamber can be predictable with the known flow rate of helium through the fabricated leaks.