US3842269A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Mass spectrometer of high detection efficiency
Assignee: Max-Planck-Gesellschaft zur Förderung der Wissenschaften eV
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Filing: 1973-12-26
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Granted: 1974-10-15
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Expires: 1993-12-26
Abstract
Abstract The ion source of a mass spectrometer is designed to draw ions from a relatively large volume through a diaphragm with a relatively large opening into a magnetic field in a wedge shaped space between diverging plane pole faces, entering such space parallel to the line of intersection of the pole face planes near the wide end of said space. The ions are focused after 90* deflection into an exit slit or diaphragm on the line of intersection of the pole faces. Certain parameters for the position of the exit slit are given.
Inventors
- 👤 H Liebl
- 👤 K Rasskopf
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:15
CPC Classifications
H; H01; H01J; H01J49/00; H01J49/02; H01J49/10; H01J49/14
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
469 words
A mass spectrometer of high detection efficiency comprising: an ion source (20) including a chamber in which a rarified gas to be analyzed is adapted to be ionized, a metallic open helix (22) surrounding a portion of said chamber, a source of electrons (21) outside said helix, open grids (23, 24) adjacent to and obstructing the two ends of said helix (22), a first diaphragm (25) spaced from one end of said helix (22) centered axially thereto, an open grid (25a) across the opening of said first diaphragm, each of the aforesaid grids (23, 24, 25a) perpendicular to the axis (22a) of said helix (22), and means for applying electric potential (16) so as to make said grid (23) adjacent the end of said helix (22) farthest from sid first diaphragm (25) mOst positive, said grid (24) adjacent the other end of said helix (22) slightly less positive, said helix (22) at a potential intermediate that of said end grids (23, 24), said electron source (21) considerably less positive, and said frst diaphragm (25) and its grid (25i a), most negative, the voltage between said end grids (23, 24) of said helix being less than 5 percent of the acceleration voltage between the said open grid (24) at the end of said helix (22) nearer said first diaphragm (25) and the open grid (25a) across said first diaphragm; means for producing a substantially steady magnetic field (11, 28, 29) directed at right angles to the axis (22a) of said helix (22) of said ion source (20) including two pole pieces (11) having diverging pole faces (11a, 11b) lying in planes intersecting in a line (10) parallel to the axis (22a) of said helix (22) of said ion source (20) and each having also first and second mutually perpendicular sides (11c, 11d) forming edges with said pole faces (11a, 11b), said first sides (11d) being perpendicular to the axis (22a) of said helix (22) and said second sides (11c), being parallel to the line of intersection (10) of said pole face planes and respectively intersecting said diverging pole faces (11a, 11b) in lines defining their edge of nearest approach and hence also defining the throat of the space enclosed by said diverging faces, and a second diaphragm (12) in the form of a slit bisected by said line of intersection (10) of said pole face planes, said second diaphragm (12) being at a distance A0 from a boundary plane comprising said second sides (11c) of said pole pieces which is parallel to said line of intersection (10) as aforesaid, being also offset by a distance of substantially 1.35 A0 from a plane comprising said first sides (11d) of said pole pieces, and being further offset by a distance of substantially 2.10 A0 from said axis (22a) of said helix (22).
Claim 2
Dependent Claim
469 words
A mass spectrometer of high detection efficiency comprising: an ion source (20) including a chamber in which a rarified gas to be analyzed is adapted to be ionized, a metallic open helix (22) surrounding a portion of said chamber, a source of electrons (21) outside said helix, open grids (23, 24) adjacent to and obstructing the two ends of said helix (22), a first diaphragm (25) spaced from one end of said helix (22) centered axially thereto, an open grid (25a) across the opening of said first diaphragm, each of the aforesaid grids (23, 24, 25a) perpendicular to the axis (22a) of said helix (22), and means for applying electric potential (16) so as to make said grid (23) adjacent the end of said helix (22) farthest from sid first diaphragm (25) mOst positive, said grid (24) adjacent the other end of said helix (22) slightly less positive, said helix (22) at a potential intermediate that of said end grids (23, 24), said electron source (21) considerably less positive, and said frst diaphragm (25) and its grid (25i a), most negative, the voltage between said end grids (23, 24) of said helix being less than 5 percent of the acceleration voltage between the said open grid (24) at the end of said helix (22) nearer said first diaphragm (25) and the open grid (25a) across said first diaphragm; means for producing a substantially steady magnetic field (11, 28, 29) directed at right angles to the axis (22a) of said helix (22) of said ion source (20) including two pole pieces (11) having diverging pole faces (11a, 11b) lying in planes intersecting in a line (10) parallel to the axis (22a) of said helix (22) of said ion source (20) and each having also first and second mutually perpendicular sides (11c, 11d) forming edges with said pole faces (11a, 11b), said first sides (11d) being perpendicular to the axis (22a) of said helix (22) and said second sides (11c), being parallel to the line of intersection (10) of said pole face planes and respectively intersecting said diverging pole faces (11a, 11b) in lines defining their edge of nearest approach and hence also defining the throat of the space enclosed by said diverging faces, and a second diaphragm (12) in the form of a slit bisected by said line of intersection (10) of said pole face planes, said second diaphragm (12) being at a distance A0 from a boundary plane comprising said second sides (11c) of said pole pieces which is parallel to said line of intersection (10) as aforesaid, being also offset by a distance of substantially 1.35 A0 from a plane comprising said first sides (11d) of said pole pieces, and being further offset by a distance of substantially 2.10 A0 from said axis (22a) of said helix (22).
Claim 3
Dependent Claim
56 words
A mass spectrometer as defined in claim 1 in which said second diaphragm (12) has an opening which is small compared to the opening of said first diaphragm (25) and in which the voltage between the open grids (23, 24) at the ends of said helix is not more than 2 percent of said acceleration voltage.
Claim 4
Dependent Claim
87 words
A mass spectrometer as defined in claim 1 in which said helix (22), said source of electrons (21) and said open grids (23, 24) at the ends of said helix are surrounded by an electrostatic screen (26) which also encloses the end of said helix (22) farthest from said first diaphragm (25) and in which said electrostatic screen (26) is connected to said means for applying electric potential (16) so that it is at a potential in the neighborhood of that of said source of electrons (21).
Claim 5
Dependent Claim
63 words
A mass spectrometer as defined in claim 3 in which said source of electrons (21) is a thermionic cathode of substantially hairpin shape and in which said electrostatic screen (26) is connected to said means for applying of potential (16) so as to maintain it at a voltage slightly more negative than the potential at which said source of electrons (21) is maintained.
Claim 6
Dependent Claim
35 words
A mass spectrometer as defined in claim 1 in which said open grids (23, 24) adjacent to the extremeties of said helix (22) are electrically connected to the respectively adjacent ends of said helix (22).
Claim 7
Dependent Claim
68 words
A mass spectrometer as defined in claim 1 in which there are provided means for varying either the acceleration voltage or the magnetic field strength, or both, said acceleration voltage being defined as a voltage between said first diaphragm (25) and its grid (25a) and that one (24) of said open grids (23, 24) which is adjacent the end of said helix (22) nearer said first diaphragm (25).
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-14 | 1978-04-15 | 1978-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-14 | 1982-04-15 | 1982-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-14 | 1986-04-15 | 1986-10-15 | $7700.00 | Window Closed / Lapsed |