Depression of Insulator Charging in Vacuum by Partial Mechanical Processing

This paper describes experimental results on surface charging of partially mechanically processed insulators in vacuum. The charging phenomena were observed when insulators were exposed to a ramped dc voltage, by using a capacitive probe embedded in the cathode. First, we examined a partially roughened cylindrical insulator. The height of the roughened surface measured from the cathode, was varied while keeping the total length of the insulator constant. Second, in the same way, we examined a cylindrical insulator having a truncated conical frustum or a chamfer at its cathode-side end. Based on these experiments we have proved that the partial mechanical processing is effective for suppressing insulator charging in vacuum