Magnetic field immersion model electron gun and magnetic field immersion die electron gun manipulation manner

摘要

PURPOSE: To reduce color aberration and spherical aberration of an electrostatic lens system possessed by an electro gun by focusing electron beams generated from a cathode by means of the electrostatic lens the superposing strong electromagnetic field at a point where the aberration of the electron beam becomes remarkable. ;CONSTITUTION: In vacuum containers 215 and 217, thermoelectrons generated at a cathode 201 are accelerated by an anode 205 to form an electron beam. The electron beam is focused on a central axis by electric field generated by an electrostatic lens. The electrostatic lens is disposed between the cathode and the anode and formed of a drawing electrode 203 close to the cathode 201 and a lens electrode 204. An annular electromagnet 220 formed of a coil a magnetic body 209 disposed around the electron beam is provide outside the vacuum container 215 so as to generate magnetic field for focusing the electron beam. Then, the annular electromagnet 220 is adjusted in its position by a moving mechanism 221 so that the peak value of the abovementioned magnetic field strength is controlled to coincide with a point where aberration is most remarkable in the electrostatic lens.;COPYRIGHT: (C)1994,JPO&Japio