PURPOSE: To prevent dielectric breakdown attributable to the secondary electrons generated from an ion beam impingement portion as a result of impingement of deflected ion beams.
CONSTITUTION: In an ion beam apparatus comprising deflection electrodes 9, 10 for deflecting the travel orbit of an ion beam 3 running within a vacuum container 4, and an impinging electrode 14 for causing the ion beam 3 to impinge thereupon so as to cut off the ion beam 3, a bias power supply 15 is provided for biasing the impinging electrode 14 toward a positive side from the potential of the vacuum container 4. The secondary electrons 16 generated from the impinging electrode 14 as a result of impingement of ion beams thereupon are subjected to repulsion by an earth potential of the inner walls of the vacuum container 4 and returned back to the impinging electrode 14.
Kimiaki Ando
Nao Tanabe
