DEVELOPMENT OF AN R&D ELECTROSTATIC SEPTUM FOR THE 50-GEV PROTON SYNCHROTRON

The electrostatic septum for the slow extraction system of the JHF 50-GeV proton synchrotron is one of the crucial hardware components. Its required electric field strength is 6.8 MV/m in the gap of 25 mm and the length of 1.5 m. The voltage across the gap becomes 170 kV. In order to achieve these design goals, we started R&D by making a septum model. The feedthrough has a ceramics cylinder filled with Fluorinert ™ as an insulating material. The wires are 80 µm in diameter and arranged with a 1.25 mm spacing; the material is W(97%)-Re(3%). The cathode material is stainless steel (SUS304), and the length is 0.7 m. We have attained a field strength of 7.3 MV/m (183 kV/25 mm), which is higher than the goal of 6.8 MV/m (170 kV/25 mm), and 10.5 MV/m with a gap of 10 mm.