Implementation of multi-opening orifices in the primary metrology of vacuums and small gas throughputs

A multi-opening orifice is a device for the primary measurement of gas flows and related vacuum quantities. This device maintains a constant molecular flow regime and thus the possibility to very accurately calculate the conductance from the geometrical dimensions for relatively high pressures, and the value of the conductance is sufficiently high to achieve reasonable parameters of the vacuum system in use. Suitable shapes of a multi-opening orifice duct and the principles of multi-opening orifice design are discussed. An example of the multi-opening orifice manufactured with grinding is given. The limits and requirements for further development are drafted.