MASS SPECTROMETER ION GUIDE PROVIDING AXIAL FIELD, AND METHOD
First Claim
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1. An ion guide comprising:
- a plurality of rods, arranged in multipole about an axis that extends lengthwise from a first end to a second end of said ion guide, to guide ions in a guide region along and about said axis;
wherein each of said plurality of rods is closer to said axis proximate said first end of said ion guide than said axis proximate said second end of said ion guide;
a conductive casing surrounding said plurality of rods;
at least one voltage source, interconnected to said plurality of rods and to said casing to produce a voltage gradient between said casing and said axis, said voltage gradient having a different magnitude at different positions along said axis to produce an axial electric field along said axis.
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Abstract
An ion guide includes a plurality of rods, arranged about an axis that extends lengthwise from one end to the other of the guide. The rods guide ions in a guide region along and about the axis. A conductive casing surrounds the rods. The casing and the rods are geometrically arranged to produce an axial electric field along the axis. Specifically, the geometry is such that a first constant applied DC voltage (UDC), applied to the rods, and a second constant applied DC voltage (UCASE) applied to the casing, produce a voltage gradient between said casing and said axis that has a different magnitude at different positions along said axis.
56 Citations
31 Claims
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1. An ion guide comprising:
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a plurality of rods, arranged in multipole about an axis that extends lengthwise from a first end to a second end of said ion guide, to guide ions in a guide region along and about said axis; wherein each of said plurality of rods is closer to said axis proximate said first end of said ion guide than said axis proximate said second end of said ion guide; a conductive casing surrounding said plurality of rods; at least one voltage source, interconnected to said plurality of rods and to said casing to produce a voltage gradient between said casing and said axis, said voltage gradient having a different magnitude at different positions along said axis to produce an axial electric field along said axis. - View Dependent Claims (2, 3, 4)
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5. An ion guide comprising:
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a plurality of rods, arranged about an axis that extends lengthwise from a first end to a second end of said ion guide, to guide ions in a guide region along and about said axis; a conductive casing surrounding said plurality of rods; wherein said casing and said plurality of rods are geometrically arranged so that a first constant applied DC voltage (UDC) applied to said rods, and a second constant applied DC voltage (UCASE) applied to said conductive casing, produce a voltage gradient between said casing and said axis that has a different magnitude at different positions along said axis, to produce an axial electric field along said axis. - View Dependent Claims (13, 14, 17, 19, 20, 21, 23, 25)
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6. (canceled)
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26. A method comprising:
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providing a plurality of rods about an axis that extends lengthwise from a first end to a second end to guide ions in a guide region along and about said axis; providing a conductive casing surrounding said plurality of rods creating a multipolar electric field between said plurality of rods to contain ions in said guide region, applying a substantially DC voltage to said conductive casing and said rods, wherein said casing and said plurality of rods are geometrically arranged so that said substantially DC voltage to said casing and said rods, produce a voltage gradient between said casing and said axis that has a different magnitude at different positions along said axis, to produce an axial electric field along said axis. - View Dependent Claims (27, 29, 30, 31)
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28. (canceled)
Specification