Robert M Crawford

US Patent:

6486469, Nov 26, 2002

Filed:

Oct 29, 1999

Appl. No.:

09/429063

Inventors:

Steven M. Fischer - Hayward CA
Robert K. Crawford - Palo Alto CA

Assignee:

Agilent Technologies, Inc. - Palo Alto CA

International Classification:

B01D 5944

US Classification:

250288, 250281, 250290, 250293

Abstract:

For delivery of ions from a higher pressure ion source to a mass analyzer operating at high vacuum, high pass ion filtration is effected within a dielectric capillary interface between the higher pressure ionization chamber and the lower pressure environment of a mass analyzer, by application of electrical potentials to end electrodes and to at least one electrode associated with the dielectric capillary between the ends, to create an end-to-end electric field generally opposing gas flow-assisted movement of ions from the upstream end to the downstream end, and to create a steeper voltage gradient along an upstream portion than along a downstream portion of the capillary. The voltage gradient along the steeper upstream portion of the capillary is sufficiently steep to cause ions having drift velocities below a lower limit to stall within the capillary. The respective potentials may be adjusted to increase the steepness of the upstream voltage gradient to increase the drift velocity lower limit.

US Patent:

6546607, Apr 15, 2003

Filed:

Apr 3, 2000

Appl. No.:

09/541863

Inventors:

Robert K. Crawford - Palo Alto CA
J. Gerson Goldberg - Mountain View CA

Assignee:

Agilent Technologies, Inc. - Palo Alto CA

International Classification:

H01G 700

US Classification:

29 2542, 29 2541, 29841, 29846, 29852, 427 79, 427 97, 427123, 427230

Abstract:

A method for forming a crater-style sampling capacitor. The capacitor includes a dielectric having a smooth crater shaped input electrode on a first surface and output and guard electrodes on a second surface. A sampling capacitor is defined by the input and output electrodes, and a guard capacitor is defined by the input and guard electrodes. The edge of input electrode is positioned below the first surface to increase surface flash over voltage, further, the input electrode is curved to eliminate corona discharge at edges of the input electrode and to reduce self-heating to negligible levels. The apparatus is suitable for high-voltage radio-frequency applications, such as a mass spectrometer, or other high-voltage applications that require an accurate sampling capacitor for amplitude control and accurate sampling of radio-frequency wave-forms.

US Patent:

6647347, Nov 11, 2003

Filed:

Jul 26, 2000

Appl. No.:

09/625909

Inventors:

Randy K. Roushall - Redwood City CA
Robert K. Crawford - Palo Alto CA

Assignee:

Agilent Technologies, Inc. - Palo Alto CA

International Classification:

G06F 1900

US Classification:

702 75, 25039008

Abstract:

Improved data acquisition systems and methods that enable large numbers of data samples to be accumulated rapidly with low noise are described. In accordance with this inventive approach, a plurality of data samples is produced from a transient sequence in response to sampling clock, and corresponding data samples across the transient sequence are accumulated in response to an accumulation clock that is shifted in phase relative to the sampling clock.

US Patent:

6661003, Dec 9, 2003

Filed:

Aug 20, 2002

Appl. No.:

10/224637

Inventors:

Steven M. Fischer - Hayward CA
Robert K. Crawford - Palo Alto CA

Assignee:

Agilent Technologies, Inc. - Palo Alto CA

International Classification:

B01D 5944

US Classification:

250288, 250281, 250283

Abstract:

For delivery of ions from a higher pressure ion source to a mass analyzer operating at high vacuum, high pass ion filtration is effected within a dielectric capillary interface between the higher pressure ionization chamber and the lower pressure environment of a mass analyzer, by application of electrical potentials to end electrodes and to at least one electrode associated with the dielectric capillary between the ends, to create an end-to-end electric field generally opposing gas flow-assisted movement of ions from the upstream end to the downstream end, and to create a steeper voltage gradient along an upstream portion than along a downstream portion of the capillary. The voltage gradient along the steeper upstream portion of the capillary is sufficiently steep to cause ions having drift velocities below a lower limit to stall within the capillary. The respective potentials may be adjusted to increase the steepness of the upstream voltage gradient to increase the drift velocity lower limit.

US Patent:

6878931, Apr 12, 2005

Filed:

Jul 26, 2000

Appl. No.:

09/625916

Inventors:

Randy K. Roushall - Redwood City CA, US
Robert K. Crawford - Palo Alto CA, US

Assignee:

Agilent Technologies, Inc. - Palo Alto CA

International Classification:

B01D059/44
H01J049/00

US Classification:

250287, 250286, 250288, 250281, 250282, 250283

Abstract:

Improved data acquisition systems and methods that enable large numbers of data samples to be accumulated rapidly with low noise are described. In one aspect, a data acquisition system includes an accumulator that has two or more parallel accumulation paths and is configured to accumulate corresponding data samples across a transient sequence through different accumulation paths.

US Patent:

6998605, Feb 14, 2006

Filed:

May 25, 2000

Appl. No.:

09/579276

Inventors:

William D. Frazer - Mountain View CA, US
Steven M. Fischer - Hayward CA, US
Robert K. Crawford - Palo Alto CA, US

Assignee:

Agilent Technologies, Inc. - Palo Alto CA

International Classification:

B01D 59/44
H01J 49/00

US Classification:

250281, 250282, 250287, 250288, 250292, 250423 R, 250423 F, 250424, 250425

Abstract:

The present invention relates to an apparatus for delivering ions to a vacuum chamber. The apparatus comprises an ionization chamber, an ionization region within the ionization chamber, a vacuum interface at a vacuum interface voltage and a vacuum chamber, wherein the ionization chamber communicates with the vacuum chamber through the vacuum interface. Sample is introduced into the ionization chamber from an electrospray assembly at approximately ground potential. Two electrodes are provided within the chamber such that three electric fields are generated, a first field extending from the electrospray assembly to the first electrode, a second field extending from the second electrode to the first electrode, and a third field extending from the second electrode to the vacuum interface. Ions are forced to travel through the fields in order before entering the vacuum chamber. In addition, the invention provides a method of delivering ions to a vacuum chamber.

US Patent:

7041966, May 9, 2006

Filed:

Oct 29, 2004

Appl. No.:

10/977179

Inventors:

William D. Frazer - Mountain View CA, US
Steven M. Fischer - Hayward CA, US
Robert K. Crawford - Palo Alto CA, US

Assignee:

Agilent Technologies, Inc. - Palo Alto CA

International Classification:

B01D 59/44
H01J 49/00

US Classification:

250281, 250282, 250287, 250288, 250292, 250423 R, 250423 F, 250424, 250425

Abstract:

The present invention relates to an apparatus for delivering ions to a vacuum chamber. The apparatus comprises an ionization chamber, an ionization region within the ionization chamber, a vacuum interface at a vacuum interface voltage and a vacuum chamber, wherein the ionization chamber communicates with the vacuum chamber through the vacuum interface. Sample is introduced into the ionization chamber from an electrospray assembly at approximately ground potential. Two electrodes are provided within the chamber such that three electric fields are generated, a first field extending from the electrospray assembly to the first electrode, a second field extending from the second electrode to the first electrode, and a third field extending from the second electrode to the vacuum interface. Ions are forced to travel through the fields in order before entering the vacuum chamber. In addition, the invention provides a method of delivering ions to a vacuum chamber.

US Patent:

7064322, Jun 20, 2006

Filed:

Oct 1, 2004

Appl. No.:

10/956585

Inventors:

Robert K. Crawford - Palo Alto CA, US
James L. Bertsch - Palo Alto CA, US

Assignee:

Agilent Technologies, Inc. - Palo Alto CA

International Classification:

H01J 49/00

US Classification:

250290, 250288, 250282, 250292

Abstract:

The invention provides a multipole device for a mass spectrometer system. In general, the multipole device contains a plurality of conductive rods each comprising a conductive layer, a resistive layer, and an insulative layer between the conductive and resistive layers. The invention finds use in a variety of applications, including ion transport, ion fragmentation and ion mass filtration. Accordingly, the invention may be employed in a variety of mass spectrometer systems.