RF Transmission Cable Assembly

RF transmission cable assemblies and RF feedthrough assemblies both carry high-power RF signal from the generator and matching network into the chamber, solving two different problems along that path: the cable carries the signal with minimal loss over distance, and the feedthrough gets that signal through the vacuum chamber's wall without breaking the vacuum seal.

The feedthrough has to maintain vacuum integrity and RF performance simultaneously, which is a harder joint engineering problem than either requirement alone. A vacuum feedthrough's primary job is sealing — keeping atmosphere out of the chamber through the port where the conductor passes — but it also has to preserve the RF signal's impedance and power-handling capability right at that crossing point; a feedthrough that seals well but introduces RF loss or a bad impedance transition undermines the carefully matched power delivery the rest of the system was tuned to achieve.

Cable loss at RF frequencies isn't negligible, which is why transmission cable assemblies for plasma power are purpose-built rather than generic coaxial cable. Standard cable loses more power per meter at RF frequencies than it would at DC, and the kilowatt-range power levels plasma generators deliver mean even a small percentage loss translates into real, wasted power and real heat generated inside the cable itself — RF transmission cable assemblies for plasma systems are selected and rated specifically for these higher power levels and frequencies, not treated as an interchangeable commodity cable.

RF transmission cable and feedthrough assemblies together carry power along the one path that connects the carefully tuned generator-and-match system to the actual plasma, and any loss or impedance mismatch introduced along either piece of that path directly undoes some of the precision the rest of the RF power delivery chain was built to achieve.