Fusion Message Board

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Subject: Re: HV insulator feedthroughs
Date: Nov 17, 4:24 pm
Poster: Richard Hull

On Nov 17, 4:24 pm, Richard Hull wrote:

>These are 18mm plugs and they are "rebuildable." The insulator is set into the body with a packing nut kind of arrangement and the inner electrode is also held in the insulator with a nut. The whole unit breaks down into its individual components.
>In this case the center electrode could be replaced by the stainless rod "stalk" for the center grid, but I had not thought of trimming back the threaded part, seems I was thinking I might could use the threads for mounting the plug in my base plate - foolishly neglecting the effects the hv might have with the "stalk" so close to the body of the plug.
>This plug is somewhat larger than your standard 14mm and the extra space might let you dump more power through it. ?
>Planning for down the road, miniature plugs might be used for the insulated leads into an ion gun?


Those old repairable plugs are really nice, but are now virtual collector's items! It was related to the old mentality of just fixing what is broken and not throwing away the entire plug when just the points were shot. Another era long before our throw away, trash culture of today.

Ultra miniature plugs are available form certain model airplane engine suppy stores as not all of the engines use or used glow plugs in the past.
The threads on a modern car plug would get in the way and limit the ultimate voltage. That is why I cut them off and added the alumina TIG gas nozzle as an additional insulator cup. Check out the pix of the real expensive vacuum feedthroughs in the Lesker catalog (what a wish book!!!)

The larger plugs you have will indeed handle more voltage than modern stuff.

Richard Hull