| 摘要 |
<p>An electron gun comprising a source (2) with electron-emitting micro-points, an anode (8) spaced apart from the micro-points, a device (16) for applying a high voltage to the anode, and a set (10) of electrodes distributed around the beam from the source to strip focus the beam onto the anode, and acting as an electrostatic shield for shielding the source from the high voltage, said set of electrodes being arranged between the source and the anode and comprising two or more different-sized pairs of electrodes (18a, 18b, 20a, 20b) at positive and negative voltages respectively, their value being such that a weak electrostatic field is generated between the source and the set of electrodes while a strong electrostatic field is generated between the set of electrodes and the anode. The gun further comprises a device for applying medium voltage to the set of electrodes, and a device for applying a suitable voltage to the micro-points.</p> |
