| 摘要 |
In an ion beam apparatus a structure for controlling the surface potential of the target comprising an electron source adjacent to the beam for providing electrons to the beam and means between the target and source for inhibiting rectilinear radiations, i.e., electron and other particle and photon radiations between said source and said target. This prevents heating of the target by the electron source and cross-contamination between the source and the target. The apparatus further includes means for maintaining said shield means at a lower temperature than said target. A further structure is provided for the measurement of the ion beam current while controlling said surface potential of the target which includes: walls adjacent to and electrically insulated from the target and surrounding the beam whereby the walls and target provide a Faraday Cage, means for introducing variable quantities of electrons into the beam within the Faraday Cage, means for measuring the target current, means for combining and measuring the target and wall currents to provide said ion beam current measurement and means for varying the quantities of introduced electrons to control the target current and thereby the target surface potential. Likewise, this apparatus further includes means for maintaining said shielding means at a temperature lower than said target. |
