| 摘要 |
An illumination method and device has a micro-wave powered plasma source contained by a windowless plasma containment structure. When incorporated as a photo-ionization device in an ion mobility spectrometer (IMS), the resolution of the spectrometer may be improved by operation at higher pressures and through selective ionization of elements and compounds. A gas flows into a discharge gap of a micro-wave ring resonator, but is restricted from flowing away by the windowless containment structure. When microwave power is supplied, the discharge gap is energized and a plasma initiated and sustained. Photons emitted by the plasma photo-ionize a sample gas. As the containment structure is windowless, the wavelength of the emitted radiation depends on the plasma-forming gas, not on the transmission characteristics of a window material. The range of substances in the sample that are ionized may be influenced by selecting the plasma-forming gas.
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