PURPOSE: To obtain a hot-cathode electron impact type ion source of high sensitivity which is used for a tetrode analyzer by installing a hot cathode around an anode and by installing doughnut-like electrodes (which constitute an electron diaphragm electrode) over and under the hot cathode.
CONSTITUTION: An annular hot cathode 3 is installed around a cylindrical cage- like anode 1 which has an electron permeable grid-like or mesh-like circumferential area. At the same time, doughnut-like electrode plates 21 and 22 (which constitute an electron diaphragm electrode 2) are installed over and under the cathode 3, thereby constituting a hot-cathode electron impact type ion source for a tetrode analyzer. As a result, it is possible to concentrate thermions discharged from the hot cathode 3 efficiently in the cylindrical cage-like anode 1 without deteriorating the electron diaphragm effect, thereby obtaining an ion source of high sensitivity.
KOMAKI SHIYOUJIROU
MIYAMOTO MASAO
ITOU TAKAO
WATANABE FUMIO