| 摘要 |
PURPOSE:To obtain a highly sensitive mass spectrometer causing no discharge phenomenon by constituting the application structure of the ion acceleration voltage so that a switching is capable to set shield tubes, an analyzing tube, outgoing slit, and incidence slit at the ground potential when the ion source is at a positive potential and to set them at the negative potential when the ion source is at the ground potential. CONSTITUTION:Under a condition that an ion source is at a high positive potential and an acceleration target is at the ground potential as shown by solid lines, a normal measurement is feasible as before. Since an ion source 7, housing 8, and collector housing 10 are metallic vacuum containers assembled at the ground potential, no effects are given by shield tubes 17,19, 21. However, when a transfer switch 22 is switched to the state of dotted lines, an ionization chamber 1 is set at the ground potential and the acceleration target is set at the high negative potential. Under such a condition, no discharge phenomenon occurs caused by a high potential on the ion source side. Further more, individual component elements in the acceleration field are simpler in the insulation structure and easier to apply a high potential compared with the ion source side thereby are applied with a large negative potential, thus resulting in a high ion accleration voltage. |
