| 摘要 |
PURPOSE:To increase the production rate of ions by outwardly expanding the meshy area of the anode of an ion source for a device such as a mass spectrometer and installing a cathode at the approximate focus of an electron lens formed by the expanded meshy area. CONSTITUTION:A cylindrical anode 1 has an outwardly expanded electron-permeable grid-like or meshy area 1'. An annular hot cathode 2 is placed at the approximate focus of an electron lens formed by the effect of electric field produced by the meshy protruding surface. After that, an electron beam diaphragm electrode 3 is placed between the anode 1 and the cathode 2, thereby constituting a convergence electron impact type ion source for a device such as mass spectrometer. Because of the above constitution, parallel electron beams traveling from the expanded grid 1' into the anode 1 come out from the opposite side of the anode 1 before being concentrated on the hot cathode 2 and reflected by it. After that, the reflected electron beams are attracted by the anode 1 thereby repeating the same movement. Accordingly, it is possible to greatly increase the production rate of ions. |
