| 摘要 |
PURPOSE:To rise electron density and to improve ionization efficiency, by providing convex repeller plate at inner side from circumference passing respective filaments, reflecting and colliding thermal electrons to neutral beam penetrating center domain of ionization part. CONSTITUTION:A vaporizing source 1 is heated by a coil 2 to vaporize a metal therein, jetting it to an ionization part 4 of high vacuum from a jetting nozzle 1a, and cluster is formed by adiabatic expansion. On the other hand, thermal electrons released from a filament 6 are drawn out by a grid 5, and reflected by the convex repeller plate 8. The plate 8 is provided at inner side than circumference passing respective filaments 6, thermal electrons are reflected repeatedly thereby in various directions, and collided repeatedly to cluster penetrating center domain of ionization chamber over the wide range to ionize the cluster. In this way, electron density in a space is rised and ionization efficiency is improved remarkably. |
