| 摘要 |
PURPOSE:To obtain an ion-etching negative ion source having an excellent stability by providing an anode electrode and a cathode which are negatively biased and installed in the body of an ion source, a solenoid coil installed around the body and at least two lead-out electrodes placed on the ion-discharging surface of the body. CONSTITUTION:After the internal space of the body of an ion source 23 is sufficiently vacuumed, an ionization gas is introduced from a gas introduction inlet 27. A voltage of about 50V is applied from power supply (E1) to an anode electrode 22. Thermions produced from a cathode 21 travel toward the anode electrode 22. When a magnetic field is applied by energizing a solenoid coil 26, thermions bump against gas molecules and atoms to efficiently ionize them thereby producing electric discharge. After that, the anode electrode 22 is negatively biased by means of an external power supply (E2), a first lead-out electrode 24 is negatively biased by means of a bias power supply (E3) and a second lead-out electrode 25 is positively biased by means of a bias power supply (E4) so as to discharge negative ions toward a sample 28. |
