Study of High Voltage Connectors for Coaxial Cables Used in Kicker Applications at CERN

Abstract

The CERN accelerator complex uses kicker magnets that are pulsed with voltages of up to 80 kV and pulse rise times as fast as 100 ns. For pulse transmission, special coaxial high voltage cables are used together with custom designed connectors with high dielectric strength, low partial discharges, and precise impedance. Several types of connectors are in use at CERN since decades. The aim is to develop a connector, which will be used for a polyethylene prototype cable at 60 kV, to possibly replace the existing SF6 gas filled cables. Improvements for better voltage holding and significantly reduced partial discharges have been investigated and are outlined. The connectors are simulated using Finite Element Method (FEM) analysis and are subsequently high voltage tested to identify weaknesses and finally introduce a new improved connector design. Existing connectors have been inspected, simulated, HV tested in the laboratory, and their weak points have been analyzed. The influence of triple points inside the connector and the ways to treat them were studied. The test procedure, including partial discharge measurements and inception voltage tests, is outlined. Based on the knowledge gained, a new design for future 60 kV connectors has been developed and is analyzed. Results of simulations and HV tests are presented and show the initial feasibility of the design.