Patent ID: 7628861

Claim:
A system for delivering pulses of gas, wherein each pulse comprises a desired mass of the gas, comprising: a chamber; a first valve controlling gas flow into the chamber; a second valve controlling gas flow out of the chamber; a pressure transducer providing measurements of pressure within the chamber; an input interface for providing a desired mass for each pulse of gas to be delivered by the system; a controller connected to the valves, the pressure transducer and the input interface and configured and arranged to, receive the desired mass of gas through the input interface, receive chamber pressure measurements from the pressure transducer, fill the chamber whenever the pressure within the chamber falls to a predetermined lower level by closing the second valve, opening the first valve until the pressure within the chamber rises to a predetermined upper level, wherein the first valve is closed, and deliver successive pulses of gas from the chamber by opening and closing the second valve after the first valve has been closed and whenever the pressure within the chamber is greater than the predetermined lower level, wherein each pulse is delivered by opening the second valve at time=t 0 , and closing the second valve at time=t* when the mass of gas discharged equals the desired mass, wherein the controller calculates the mass discharged when the second valve is open, and wherein the mass discharged, Δm, for each pulse is equal to, Δ m=m ( t 0 )− m ( t *)= V/R [( P ( t 0 )/ T ( t 0 ))−( P ( t *)/ T ( t *))] wherein m(t 0 ) is the mass of the gas in the chamber at time=t 0 , m(t*) is the mass of the gas in the chamber at time=t*, V is the volume of the chamber, R is equal to the universal gas constant (8.3145 J/mol K), P(t 0 ) is the pressure in the chamber at time=t 0 , P(t*) is the pressure in the chamber at time=t*, wherein for delivery of the mass of gas, the outlet valve is open for a time of about 100 milliseconds to about 500 milliseconds.