Plasma source for spectrometry
AssigneeVarian Australia PTY LTD
InventorMichael R Hammer
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Abstract
A plasma source for a spectrometer for spectrochemical analysis of a sample is characterised by use of the magnetic field component of applied microwave energy for exciting a plasma. The source includes a waveguide cavity (10) fed with TE10 mode microwave power. A plasma torch (16) passes through the cavity (10) and is axially aligned with a magnetic field maximum (18) of the applied microwave electromagnetic field. Magnetic field concentration structures such as triangular section metal bars (20) may be provided. In an alternative embodiment a resonant iris may be provided within a waveguide and the plasma torch positioned relative thereto such that the microwave electromagnetic field at the resonant iris excites the plasma.
Claims33
A method of producing a plasma for spectrochemical analysis of a sample comprising
- supplying a plasma forming gas to a plasma torch,
- applying microwave power to the plasma torch, and
- relatively positioning the plasma torch to axially align it substantially with a magnetic field maximum of the microwave electromagnetic field,
- wherein the applied microwave power is such as to maintain a plasma of the plasma forming gas for heating a sample entrained in a carrier gas for spectrochemical analysis of the sample.
A plasma source for a spectrometer comprising
- microwave generation means for generating microwave power,
- a waveguide for receiving and supplying the microwave power,
- a plasma torch having passages for supply of respectively at least a plasma gas and a carrier gas with entrained sample,
- wherein the plasma torch is positioned relative to the waveguide such that it is substantially axially aligned with a magnetic field maximum of the microwave electromagnetic field for excitation of a plasma of the plasma forming gas for heating the sample for spectrochemical analysis.
A waveguide for a microwave induced plasma source for spectrochemical analysis of a sample,
- wherein the waveguide is dimensioned to operate in the TE10 mode and includes apertures for accommodating a plasma torch, wherein the apertures are located such that in use a plasma torch located in the waveguide and extending through said apertures will be axially aligned with a magnetic field maximum of the microwave electromagnetic field.
A plasma source for a spectrometer including
- a waveguide containing a resonant iris,
- a plasma torch associated with the resonant iris such that a microwave electromagnetic field can be applied to the resonant iris via the waveguide and for a magnetic field maximum of the electromagnetic field in the resonant iris to be substantially axially aligned with the plasma torch for exciting a plasma in a plasma forming gas that passes through the plasma torch.
Dependencies are inferred from the claim text.