Measuring low vapor pressures employing the Knudsen effusion technique and a magnetic suspension balance.

A new Knudsen effusion apparatus employing a magnetic suspension balance (MSB) to measure low vapor pressures <1 Pa is presented. The intention of the work is developing a method for measuring vapor pressures that covers a wider range of pressure than established procedures do. A cooled condensation plate is used to collect a large fraction of effused molecules which have left a Knudsen cell.