| 摘要 |
A flowing discharge ion source for supplying negative and positive ions to a mass spectrometer has an elongated, confined flow and discharge region through which flow the sample to be analyzed and a reagent gas and in which ionizing discharge electrodes are located. Inlet and outlet gas flow orifices are independently variable so that the reagent gas pressure in the discharge region and flow velocity therethrough are controlled. Controlling flow velocity provides one way for determining reagent and sample gas residence time, which is further controlled by making the position of the discharge electrodes adjustable along the length of the ionization region. A controllable heater is provided upstream of the discharge region to regulate reagent and sample gas temperature.
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