ION SOURCE

PURPOSE:To obtain an ion source whose operation is stabilized and which is minimally contaminated by applying voltage across a plate-like first electrode and a second electrode placed facing each other and installing a plural number of permanent magnets on the first electrode. CONSTITUTION:A magnetic field 18 parallel to a first electrode 13 is produced over the first electrode 13 by means of two facing permanent magnets 14 having different polarities. An electric field 19 perpendicular to the magnetic field 18 is produced by applying voltage across the first and the second electrodes 13 and 16. When ionized gas is introduced through a gas introduction inlet 20, molecules of the gas are ionized by bumping against rotating electrodes thereby producing plasma through electric discharge. Positive ions in the plasma are discharged through a beam hole 21 as ion beams 22. The first and the second electrodes 13 and 16 are prepared from carbon graphite, so that a polymer film hardly adheres to the electrodes 13 and 16 and stabilized operation of the ion source is achieved.