公开(公告)号：US06208711B1

公开(公告)日：2001-03-27

申请号：US09399910

申请日：1999-09-21

Applicant: Roy E. Rand ,  Khem Garewal ,  James F. Heilman

Inventor： Roy E. Rand ,  Khem Garewal ,  James F. Heilman

IPC: H01J3514

CPC classification number: G21K1/08 ,  A61B6/032 ,  A61B6/4028 ,  H01J35/02

Abstract: In a scanning electron beam CT system, a positive ion clearing electrode system is disposed within the CT system solenoid coil, and is operated from a single power source. Mounted coaxially about the electron beam, preferably the electrode system includes three sections, each having two electrode elements, one element being coupled to about −800 V to about −2 kV and the other element being grounded. Within the electrode system, the ratio between element diameter and electron beam diameter is substantially constant. Preferably elements are helically twisted about the beam axis. The electrode configuration cancels net quadrupole (focusing) and octopole (aberration-producing) fields. In the presence of electric discharge, essentially zero electron beam displacement and deflections occurs, and changes in focusing strength remain zero.

Abstract translation: 在扫描电子束CT系统中，正离子清除电极系统设置在CT系统螺线管线圈内，并从单个电源操作。 优选地，电极系统包括三个部分，每个部分具有两个电极元件，一个元件耦合到大约-800V至大约-2kV，另一个元件接地。 在电极系统内，元件直径与电子束直径之间的比率基本上是恒定的。 优选地，元件围绕光束轴线螺旋扭曲。 电极配置消除了净四极（聚焦）和八极（产生像差）场。 在放电的情况下，发生基本为零的电子束位移和偏转，并且聚焦强度的变化保持为零。