HOT-CATHODE ELECTRON IMPACT TYPE ION SOURCE

摘要

PURPOSE:To increase the extraction efficiency of ions by causing the electric field of a mesh-like electrode to intrude into the ionization chamber by installing a mesh-like electrode facing the output opening of the ionization chamber in a hot-cathode electron impact type ion source for a tetrode analyzer. CONSTITUTION:Shield electrodes 3 and 3' and an annular hot cathode 2 are placed around a cylindrical anode 1 which has an electron permeable network 1'' in its circumferential area to make an ionization chamber. After that, a lead-out electrode 4 having a network 4' is installed facing the output opening 5 of the ionization chamber so that the electric field of the electrode 4 intrudes into the ionization chamber, thereby constituting a hot-cathode electron impact type ion source for a tetrode analyzer 7. Owing to the above constitution, it is possible to introduce the magnitude and the direction of an electric field produced in an ion production space formed within the ionization chamber almost ideally toward the network 4' of the lead-out electrode 4 by controlling the structure of the network of the lead-out electrode 4 and the electric potential applied to the electrode 4. Consequently, it is possible to increase the production efficiency of ions.