| 摘要 |
PURPOSE:To obtain high sensitivity by changing the structure of a shock electron beam generating mechanism in an ion source suitable to be used for a mass spectrometer and further controlling the voltage to be applied to it. CONSTITUTION:The electrode application voltage when using an ion source is made V1 volts for a grid 16 and V2 volts for a grid 17 in relation to the potential of a filament 8. The potential between the grid 17 and an ionization chamber 1 is made V3 volts in relation to the potential of the grid 17. A shock electron beam 11 enters the ionization chamber by the energy of (V1-V2+V3) eV, then it is reflected via the action of the negative voltage of an electron collector electrode 10 and is returned into the ionization chamber 1. The electron beam 11 returned into the ionization chamber 1 is again reflected by the voltage of the grid 17 having the negative potential in relation to the ionization chamber 1 and is returned into the ionization chamber 1. Accordingly, the shock electron beam 11 is reciprocated between the grid 17 and electron collector electrode 10. Furthermore, electrons having uniform energy among shock electrons generated from the filmment 8 can be selected and guided to the ionization chamber by changing the value of the voltage V2 applied to the grid 16. |
