High Gradient Accelerating Column Design and Construction

A high voltage, high gradient accelerating column to provide good optics for high current beams has been built and tested by MURA. Design details were chosen to eliminate all possible sparking or corona discharges for reliable high voltage performance. The 12-in. accelerating gap features stainless steel spherical geometry electrodes shaped to produce a converging field. The electrodes are supported by titanium alloy spacers bonded to ceramic rings with a vinyl seal. There are 14 ceramic rings of 14 in. ID, 16 in. OD, and 1-15/32 in. long, giving a column length of 21 in. This column is insulated externally by sulfur hexafluoride gas at three atmospheres absolute pressure confined by a fiber glass pressure shell. The completed column has been tested at 600 kV. Work is being done on ceramic-to-metal seals to eliminate organic materials.