Abstract: The invention provides a cathode system for an Electron Ionization (EI) source comprising a filament and current supply posts, the current supply posts dividing the filament into segments and each current supply post supplying or returning the current for at least two segments of the filament. Each filament segment is connected, for instance by spot welding, to the supply posts delivering the heating current. The filament segments may be arranged in a row, or substantially parallel to each other. Filament segments arranged in a row may form a closed loop, for instance, a ring. Other embodiments encompass the filament shape of a helical coil.

Abstract: An apparatus and method for introducing ions into a vacuum chamber of a mass spectrometer includes producing ions in an ionization chamber of an ion source. The ions are sampled into an intermediate pressure chamber via a first ion transfer tube. In particular, the pressure within the intermediate pressure chamber is maintained at a value that exceeds a maximum pressure for being sampled into the vacuum chamber of the mass spectrometer. Some of the ions are sampled from the intermediate pressure chamber via at least a second ion transfer tube, the at least a second ion transfer tube having an outlet end that is in communication with a low-pressure chamber. In particular, the pressure within the low-pressure chamber is maintained at a value that is less than a maximum pressure for being sampled into the vacuum chamber of the mass spectrometer. Some of the ions are sampled from the low-pressure chamber into the vacuum chamber of the mass spectrometer.

Abstract: A device for transporting and focusing ions in a low vacuum or atmospheric-pressure region of a mass spectrometer is constructed from a plurality of longitudinally spaced apart electrodes to which oscillatory (e.g., radio-frequency) voltages are applied. In order to create a tapered field that focuses ions to a narrow beam near the device exit, the inter-electrode spacing or the oscillatory voltage amplitude is increased in the direction of ion travel.

Abstract: A method and apparatus for directing ions from an ionization source to a mass analyzer is provided. The method includes producing ions from a sample in an ionization source. Some of the ions are transferred to a first region via a passageway that is in fluid communication with the ionization source. Next, some of the ions are sampled from the first region into a second region via an aperture that is defined thorough a partition element. The aperture is centered about a longitudinal axis that passes through an ion transfer element within the second region. An electric field is established for deflecting some of the ions that pass through the aperture of the partition element. In particular, the electric field is directed transverse to the longitudinal axis such that relatively more ions enter an input end of the ion transfer element compared to when the ions are not deflected.

Abstract: A device for transporting and focusing ions in a low vacuum or atmospheric-pressure region of a mass spectrometer is constructed from a plurality of longitudinally spaced apart electrodes to which oscillatory (e.g., radio-frequency) voltages are applied. In order to create a tapered field that focuses ions to a narrow beam near the device exit, the inter-electrode spacing or the oscillatory voltage amplitude is increased in the direction of ion travel.

Abstract: An ion guide having a plurality of spheroidal or similarly shaped electrodes is disclosed. The electrodes are arranged in pairs about a central ion flow axis, and an RF voltage is applied in a prescribed phase relation to create an electric field that focuses and radially confines an ion beam. A defocusing effect associated with the electrode shape may be reduced by placement of a separate skirt electrode immediately downstream in the ion path, or by forming the electrodes in a composite structure, whereby the trailing portion of the electrode is fabricated from or coated with an insulative material.

Abstract: An ion source includes an ion transfer tube having two segments for transporting a sample fluid containing ions between a first chamber and a second chamber maintained at a reduced pressure relative to the first chamber. A first segment may include a plurality of channels and heat conductive walls forming the plurality of channels. The plurality of channels and walls forming the channels promote efficient convective heat transfer to the sample fluid, thereby enabling operation at relatively high sample fluid flow rates, resulting in an increase in the number of ions that may be delivered to a mass analyzer. A second segment forms a single common channel that receives a plurality of sample streams and enables them to combine into a single ion stream that may be introduced as a single gas stream expansion into the second chamber.

Abstract: An ion source includes an ion transfer tube having two segments for transporting a sample fluid containing ions between a first chamber and a second chamber maintained at a reduced pressure relative to the first chamber. A first segment may include a plurality of channels and heat conductive walls forming the plurality of channels. The plurality of channels and walls forming the channels promote efficient convective heat transfer to the sample fluid, thereby enabling operation at relatively high sample fluid flow rates, resulting in an increase in the number of ions that may be delivered to a mass analyzer. A second segment forms a single common channel that receives a plurality of sample streams and enables them to combine into a single ion stream that may be introduced as a single gas stream expansion into the second chamber.

Abstract: A method and apparatus for directing ions from an ionization source to a mass analyzer is provided. The method includes producing ions from a sample in an ionization source. Some of the ions are transferred to a first region via a passageway that is in fluid communication with the ionization source. Next, some of the ions are sampled from the first region into a second region via an aperture that is defined thorough a partition element. The aperture is centered about a longitudinal axis that passes through an ion transfer element within the second region. An electric field is established for deflecting some of the ions that pass through the aperture of the partition element. In particular, the electric field is directed transverse to the longitudinal axis such that relatively more ions enter an input end of the ion transfer element compared to when the ions are not deflected.

Abstract: An apparatus and method for introducing ions into a vacuum chamber of a mass spectrometer includes producing ions in an ionization chamber of an ion source. The ions are sampled into an intermediate pressure chamber via a first ion transfer tube. In particular, the pressure within the intermediate pressure chamber is maintained at a value that exceeds a maximum pressure for being sampled into the vacuum chamber of the mass spectrometer. Some of the ions are sampled from the intermediate pressure chamber via at least a second ion transfer tube, the at least a second ion transfer tube having an outlet end that is in communication with a low-pressure chamber. In particular, the pressure within the low-pressure chamber is maintained at a value that is less than a maximum pressure for being sampled into the vacuum chamber of the mass spectrometer. Some of the ions are sampled from the low-pressure chamber into the vacuum chamber of the mass spectrometer.

Abstract: An ion guide having a plurality of spheroidal or similarly shaped electrodes is disclosed. The electrodes are arranged in pairs about a central ion flow axis, and an RF voltage is applied in a prescribed phase relation to create an electric field that focuses and radially confines an ion beam. A defocusing effect associated with the electrode shape may be reduced by placement of a separate skirt electrode immediately downstream in the ion path, or by forming the electrodes in a composite structure, whereby the trailing portion of the electrode is fabricated from or coated with an insulative material.