Coaxial connector adapters have their place in both test and production systems. This page details the dos and don’ts of their use in plasma systems.
Coaxial adapter kits There are various multi-adapter kits available similar to the image to the right. These are typically used for low level signals (under 50 watts). Based on the quality of the included components, they may be limited to low frequencies. It is best to test the adapter for VSWR or return loss at the frequency of use. In all cases, these parts are not designed for extreme mechanical stresses or high RF currents. DO NOTuse these parts to connect the plasma output of an impedance matching network to a plasma load.
Coaxial vacuum feedthroughs Vacuum component/fitting manufacturers offer many different types of coaxial vacuum feedthroughs with all types of coaxial connectors and flanges. Be aware that some of these parts are specified for instrumentation and small signal applications only. Others are rated for use with high power RF. Our direct experience has shown that any of these components using nichrome wire as the center conductor should be avoided when used with high RF power (over 50 watts @ 13.56MHz) as the wire is lossy and changes property when the RF current is applied.