Reference leak generating device and ultra-fine leak testing device using same

Abstract

There is provided a reference leak generating device capable of precisely generating an ultra-fine reference leak. The reference leak generating device adapted to be connected to an upstream side of a measurement chamber includes a chamber connected to the measurement chamber through an orifice or a porous plug having a molecular flow conductance C and a pressure to establish molecular flow conditions which are known in advance, and is characterized in that a pressure p 1 of testing gas to be introduced into the chamber is precisely determined by using a static expansion method once or more times, and a leak rate of a reference leak at the pressure p 1 is obtained in accordance with a product of C and p 1 .

1 . A reference leak generating device adapted to be connected to an upstream side of a measurement chamber, comprising:
 a chamber connected to the measurement chamber through an orifice or a porous plug having a molecular flow conductance C and a pressure to establish molecular flow conditions which are known in advance,   wherein a pressure p 1  of testing gas to be introduced into the chamber is precisely determined by a static expansion method of one time or more, and is set so that testing gas flowing through the orifice or the porous plug satisfies the molecular flow conditions, and a leak rate of a reference leak at the pressure p 1  is obtained in accordance with a product of C and p 1 .   
     
     
         2 . The reference leak generating device according to  claim 1 , wherein the static expansion method is performed by expanding a volume of testing gas from V 0  to V 0 +V 1  between a second chamber of the volume V 1  which is connected to the upstream side of the measurement chamber and a first chamber of the volume V 0  which is connected to an upstream side of the second chamber. 
     
     
         3 . An ultra-fine leak testing device or an outgassing measurement device comprising a reference leak generating section constituted of the reference leak generating device according to  claim 1 , and a fine leak measuring section,
 said fine leak measuring section including a measurement chamber for measuring a leak or an outgassing from a test piece, a partial pressure analyzer connected to the measurement chamber, and an entrapment vacuum pump connected to the measurement chamber and adapted not to trap testing gas,   said reference leak generating section comprising, on the upstream side of the measurement chamber, the chamber connected to the measurement chamber through the orifice or the porous plug having the molecular flow conductance C and the pressure to establish the molecular flow conditions which are known in advance,   wherein the pressure p 1  of testing gas to be introduced into the chamber is precisely determined by using the static expansion method once or more times, and is set so that testing gas flowing through the orifice or the porous plug satisfies the molecular flow conditions, the leak rate of the reference leak at this time is obtained in accordance with the product of C and p 1 , an increasing rate of a partial pressure of testing gas is measured with the partial pressure analyzer, and an increasing rate of an output signal of the partial pressure analyzer is compared with the leak rate of the reference leak to perform calibration.   
     
     
         4 . The ultra-fine leak testing device or the outgassing measurement device according to  claim 3 , wherein testing gas is inert gas such as helium or the like. 
     
     
         5 . An ultra-fine leak testing device or an outgassing/permeation measurement device comprising a reference leak generating section constituted of the reference leak generating device according to  claim 1 , and a fine leak measuring section,
 said fine leak measuring section including a measurement chamber for measuring a leak or an outgassing from a test piece, a partial pressure analyzer connected to the measurement chamber, and a kinetic vacuum pump connected to the measurement chamber,   said reference leak generating section comprising, on the upstream side of the measurement chamber, the chamber connected to the measurement chamber through the orifice or the porous plug having the molecular flow conductance C and the pressure to establish the molecular flow conditions which are known in advance,   wherein the pressure p 1  of testing gas to be introduced into the chamber is precisely determined by using the static expansion method once or more times, and is set so that testing gas flowing through the orifice or the porous plug satisfies the molecular flow conditions, the leak rate of the reference leak at this time is obtained in accordance with the product of C and p 1 , and a partial pressure of testing gas in equilibrium conditions which is measured with the partial pressure analyzer is compared with the leak rate of the reference leak to perform calibration.