| 摘要 |
<p>Both focusing screens (2) are placed on a cylindrical rod (4) and are electrically isolated from a secondary-electron emitter (1), while field-emission emitters (3) are located on both screens and are separated from each other by a vacuum gap (9). The anode (10) is earthed and negative working voltage is passed to the secondary-electron emitters and the emitted electrons are accelerated by the electromagnetic field passed to the surface of the secondary-electron emitters, with secondary electrons being multiplied in cascade manner to form the working current.</p> |
