| 摘要 |
Method and apparatus are disclosed for improved transfer of ionizing particles from a source chamber to a detection zone in an ionization chamber in an ionization detector. An ionization detector includes a source chamber, an inlet for introducing detector gas to the source chamber, a transitional structure including a flow guide that directs detector gas flow between the source chamber and the adjacent ionization chamber, an inlet for introducing sample gas containing an analyte into the ionization chamber, and an outlet port for exhausting the mixture of the sample gas and the detector gas. The aspect ratio of the flow guide causes the linear velocity of the detector gas stream to be highest at a throat in the flow guide and to decrease as the detector gas stream approaches a detection zone in the ionization chamber, thereby suppressing analyte diffusion from the ionization chamber through the flow guide. The aspect ratio of the flow guide also provides an unimpeded path for transit of photons from the source chamber to the detection zone in the ionization chamber.
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