hard gold to reduce migration in plasma environment?

Are there types of so-called "hard gold" alloys that have good electrical conductivity, but are less prone to migrate in a plasma environment. I have
an rf feedthrough which is the only source of gold in the system. There is a plasma discharge running and I see gold collecting in certain areas of the discharge on metal surfaces. The gold is not directly exposed to the plasma. Has anyone encountered this problem? Solution? Does anyone have experience with gold alloys for coaxial rf feedthroughs? Detailed specifications? Good vendors? The application calls for a plating process, not vapor deposition.
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