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XRays leaking from feedthru

Posted: Mon Sep 23, 2019 5:06 pm
by Mark Rowley
This is nothing new but I haven’t seen a post about it for awhile. If anything, it’ll serve as a good reminder to folks currently building their systems.

There is always valid concern about xrays leaking from the glass viewport. However, don’t forget about the ceramic feedthru. My 2.75” system is heavily shielded with 1/8” lead and the viewport / camera arrangement is totally encompassed as well.

I generally use a pancake detector for monitoring xrays near the operating position. After pushing the fusor past 27kV I began to notice some X-ray leakage below the fusor near the feedthru. It wasn’t much, but enough to shine a bit into the operator area. After sweeping the feedthru with the pancake, it was clear this was the 2nd “window” of concern.

I then built another shield (yellow X) that dropped X-ray levels to nothing. Affixed to the backside of the panel is a sheet of 1/8” lead.

Mark Rowley

Re: XRays leaking from feedthru

Posted: Mon Sep 23, 2019 6:52 pm
by Richard Hull
Yes I noticed this and posted on it back in the old songs and early intranet forums. I also include a segment in my second fusor video tape back in 2000 showing the x-ray blast exiting the insulator area. It is wise to never let the window or the insulator face outwards towards the operator or the viewing public. 1/8" lead shielding is more than adequate shielding for 95% of all fusors. The shadow cone shied I have mentioned in the FAQs is the simplest of all shields to employ for the operator. Catches all those pesky x-rays. see the old post. Note: I will now add a small graphic image of the shield to this old 2007 posting.


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Richard Hull