Microwave plasma source
AssigneeVarian Austrailia PTY LTD
InventorMichael R. Hammer
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Abstract
A plasma source for a spectrometer includes a plasma torch (10) located within a waveguide or resonant cavity (40) for both the electric and the magnetic field components of a microwave electromagnetic field to excite a plasma (54). This produces a plasma (54) having a generally elliptical cross section into which sample is relatively easily injected but which still provides good thermal coupling between the plasma and the sample. The invention gives significantly improved limits of detection compared to prior art microwave induced plasma systems. The torch is preferably axially aligned with the direction of the magnetic field component and may be located within a resonant iris (32) within the waveguide or cavity (40).
Claims13
A plasma source for a spectrometer including
- a plasma torch having at least one passage for supply of a plasma forming gas,
- means for applying a microwave electromagnetic field to the plasma torch,
- said means being associated with the torch for both the electric and the magnetic field components of the applied microwave electromagnetic field to excite a plasma of the plasma forming gas.
A method of producing a plasma for spectrochemical analysis of a sample including relatively locating a plasma torch within a microwave electromagnetic field for both the electric and the magnetic field components of the microwave electromagnetic field to be applied to the plasma torch for both the field components simultaneously to excite a plasma in a plasma forming gas flowing through the torch.
Dependencies are inferred from the claim text.