Ion-pumped mass spectrometer leak detector apparatus and method and ion pump therefor

Claim 2

A leak detector in accordance with claim 1 in which said means for continually depositing some of said material upon said walls of said getter-ion-pumping means comprises a vapor deposition means and said source of getter material is distinct and separate from said positive ion target.

Claim 3

A leak detector in accordance with claim 3 in which the effective area for capturing gas molecules is at least five times greater than the effective area for capturing positive ions.

Claim 4

A leak detector comprising, in combination: a sealed high-vacuum system including a first portion, a second portion and a third portion; valve means between said first anD second portions and between said first and third portions; means for connecting a test vessel, exposed to a probe gas, to said first portion; a bypass portion for communicating said first portion with said third portion, said bypass portion including a membrane member which is permeable to said probe gas and impermeable to all other gases within said vacuum system; a roughing pump connected to said second portion to reduce the pressure of said high-vacuum system to roughing pressure; a mass spectrometer connected to said third portion for detecting the presence of probe gas withing said high-vacuum system; and high-vacuum pump means connected to said third portion to reduce the pressure of said high-vacuum system from roughing pressure to mass spectrometer pressure, said pump means comprising: a getter-ion-pumping means including a chamber having walls defining a space in communication with said third portion, a source of getter material, and means for continually depositing some of said getter material upon said walls for capturing gas molecules colliding with said walls, and noble-gas-pumping means disposed within said space and including a positive ion target positioned with respect to said source of getter material and said depositing means for receiving a deposit of said getter material, means for generating positive ions from at least the noble gas molecules, and means for accelerating said positive ions towards said ion target for capture by said ion target and for burial by the getter material continually being deposited upon said ion target.

Claim 5

A leak detector comprising, in combination: a sealed high-vacuum system including a first portion, a second portion and a third portion; valve means between said first and second portions and between said first and third portions; means for connecting a test vessel, exposed to a probe gas, to said first portion; a fourth portion disposed between said first portion and said third portion; throttling valve means between said first portion and said fourth portion; isolation valve means between said fourth portion and said third portion; a bypass portion for communicating said first portion with said fourth portion, said bypass portion including a membrane member which is permeable to said probe gas and impermeable to all other gases withing said vacuum system; a roughing pump connected to said second portion to reduce the pressure of said high-vacuum system to roughing pressure; a mass spectrometer connected to said third portion for detecting the presence of probe gas within said high-vacuum system; and high-vacuum pump means connected to said third portion to reduce the pressure of said high-vacuum system from roughing pressure to mass spectrometer pressure, said pump means comprising: a getter-ion-pumping means including a chamber having walls defining a space in communication with said third portion, a source of getter material, and means for continually depositing some of said getter material upon said walls for capturing gas molecules colliding with said walls; and noble-gas-pumping means disposed within said space and including a positive ion target positioned with respect to said source of getter material and said depositing means for receiving a deposit of said getter material, means for generating positive ions from at least the noble gas molecules, and means for accelerating said positive ions towards said ion target for capture by said ion target and for burial by the getter material continually being deposited upon said ion target.

Claim 6

A vacuum pump comprising: an evacuable chamber having a wall defining a main and an auxiliary space adapted to contain gas molecules and including means for coupling said chamber to an evacuable system said main space being larger than said auxiliary space, a source of getter material disposed withing said main space; means for vaporizing some of said getter material from said source And for depositing the vapor upon the wall defining said chamber to absorb gas molecules coming into contact with said walls; cathode means immovably disposed within said auxiliary space and positioned to have deposited thereon a portion of said vaporized getter material; means for connecting said cathode means to a source of negative potential with respect to the potential of said walls to provide an electric field; and means for providing a magnetic field in a selected direction across said auxiliary space and of such an extent that at least the major portion of said cathode means lies within said magnetic field whereby some of said gas molecules are ionized by collision with electric and magnetic field accelerated electrons for absorbing impact upon said cathode means and subsequent burial by the deposit of getter material thereon.

Claim 7

A vacuum pump in accordance with claim 7 in which said cathode means comprises a pair of facing cathode electrodes whose effective area comprises the major portion of the facing surfaces of said cathode electrodes, and in which said effective area is less than one-fifth of the area of said wall.

Claim 8

A vacuum pump in accordance with claim 8 in which said auxiliary space and said means for coupling are separated by said main space.

Claim 9

A vacuum pump in accordance with claim 7 in which said cathode means is constructed of a material optimizing noble-gas-ion retention after absorbing impact.