ELECTRON IMPACT, FIELD EMISSION TYPE ION SOURCE

摘要

PURPOSE:To stabilize ion current by providing a control electrode between an auxiliary electrode and an ion source, electrically connecting such control electrode and auxiliary electrode and disposing a self-bias resistance in the course of connection between such connecting point and ion source. CONSTITUTION:A control electrode 13 is disposed between a chip 2 and an auxiliary electrode 7, it is electrically connected with the auxiliary electrode 7 and a self-bias resistance 14 is inserted in the course of the connection between such connecting point and an acceleration electrode 8. When the chip 2 is irradiated with the electron beam 10 and the ion beam 11 is released, temperature of chip 2 changes due to the electron beam 10 generated from the filament, a emitted ion current i becomes i+ or -DELTAi because of a change as much as + or -DELTAi. This current flows through a bias resistance 14, controlling a voltage of control electrode 13 for the chip 2. Thereby, an ion current can be stabilized.