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US 4,047,102 AGranted
Dual chamber, high sensitivity gas sensor and pump
AssigneeVarian Associates, Inc.
InventorKimo M. Welch
Life of this patent
Estimating the term…
Abstract
Apparatus for measuring gas comprising a gas sensing unit having a gas inlet membrane and being evacuated by a sputter ion pump via a restrictive conductance. Said conductance has a very low value relative to the pumping speed of the pump, whereby a change in the pumping speed of the pump causes substantially no change in the pumping speed with which the gas sensing unit is evacuated, so that the output signal of said gas sensing unit is a true reflection of the gas entering said inlet, without distortion which would otherwise be caused by changes in pumping speed of said pump.
Claims19
Gas sensing apparatus comprising:
- a gas sensing unit;
- inlet means to said gas sensing unit comprising an inlet wall preferentially transmissive to gas under investigation;
- a gas pumping unit having means for pumping gas, and passage means forming a conductance interconnecting said sensing and pumping units;
- said sensing unit being constructed to have little or no pumping speed relative to the pumping speed of said pumping unit;
- and
- the value of said conductance being small relative to the pumping speed of said pumping unit, whereby in operation the pressure in said sensing unit is higher than the pressure in said pumping unit to provide high sensitivity.
3 more elements
Gas selective sensing apparatus comprising:
- means for selecting a gas from a plurality of unseparated gases for sensing said selected gas;
- an ion-forming and collecting unit having an anode, cathode means spaced from said anode, and means for forming a magnetic field for causing electrons to follow a circuitous route in reaching said anode, said ion-forming and collecting unit being connected to said gas selecting means;
- a sputter-ion pump unit having an anode, cathode means spaced from said anode, and means for forming a magnetic field for causing electrons to follow a circuitous route in reaching said anode, said cathode means in said sputter-ion pump unit being of a material which provides substantial pumping and said cathode means in said ion-forming and collecting unit being of a material which provides little or no pumping relative to the pumping provided by said sputter-ion pump unit;
- passage means forming a conductance interconnecting said pump unit and said ion-forming and collecting unit;
- and
- the value of said conductance being small relative to the pumping speed of said sputter-ion pumping unit, whereby in operation the pressure in said ion-forming and collecting unit is higher than the pressure in said pumping unit to provide high sensitivity.
3 more elements
Apparatus for sensing the content of particular gas in a container comprising:
- a sensing chamber whose interior cavity is coupled to said container via a membrane, said sensing chamber comprising at least one cell, said cell including an anode and a cathode, said membrane having gas specific transmission characteristics whereby in a mixture of gases a particular gas is selectively admitted to said sensing chamber, said cathode being chemically inert with respect to said selected gas;
- and
- a pumping chamber comprising a gas pump, said pumping chamber's interior cavity being coupled to the interior cavity of said sensing chamber via conducting means whose conductance is small in relation to the pumping speed of said pumping chamber, whereby in operation the pressure in said sensing chamber is higher than the pressure in said pumping chamber to provide high sensitivity.
Apparatus for sensing gas present outside said apparatus comprising:
- a sensing chamber having a gas-permeable inlet membrane, said sensing chamber comprising at least one sensor cell, said sensor cell comprising an anode and a chemically non-active cathode;
- a pumping chamber comprising a sputter-ion pump with at least one pumping cell, said pumping cell comprising an anode and a chemically active cathode, the interior cavity of said pumping chamber being coupled to the interior cavity of said sensing chamber via a small aperture conducting means whose conductance is small in comparison with the pumping speed of said pumping chamber, whereby in operation the pressure in said sensing chamber is higher than the pressure in said pumping chamber to provide high sensitivity;
- and
- means to measure the electrical current flowing through the cathode of said sensing chamber.
1 more element
A method of sensing gas comprising the steps of:
- communicating a pressure sensing unit with an unknown concentration of gas;
- pumping gas out of said sensing unit by means of a pumping unit connected to the sensing unit via a restricted conductance;
- said pumping being performed at a pumping speed which is high relative to the value of said conductance to obtain a pressure in said sensing unit which is higher than the pressure in said pumping unit to provide high sensitivity in said sensing unit;
- and
- using the output of said pressure sensing unit to obtain information about said unknown concentration of gas.
2 more elements
Dependencies are inferred from the claim text.