HV Feedthrough Build
Posted: Thu Dec 22, 2011 2:24 am
Thought I'd share my new feedthrough that I'll put to test in a few days (flying home tomorrow for winter break). It is basically a copy of Doug's design. I'm using 1"OD 0.157" Wall Pyrex, with an inside 5/8"OD 0.094" Wall Pyrex slip-fit.
I found a nice way to make the end plug go in and out forever without any need for lube and without ever damaging the o-rings (diamond chamfering helps but didn't fully solve the problem from what I tried). I just put the tube in the lathe, and torched the end for a minute or two and it, and it flared out adding probably 0.1" to the diameter (forgot to measure it, now it's all packed up for the flight home tomorrow). Just enough to let the o-ring not touch the glass as it first slides in, but be in full contact after sliding in an inch. As long as you do this to only one side it doesn't interfere with its use since you can always put the quick-coupling on from the other side. Although if it really bothers you to have it only single-side access on that, you can carve off the excess from the outside of the tube until it fits into the coupling. I did that on a few of my tubes then realized there's really no point and just left it after flaring.
I'll post back hopefully next week with how it's working, excited to use this with my feedback-regulated power supply and hopefully get a few million n/s at a stability that I can just sit back and activate stuff forever. Never really had good stability in my fusor.
I found a nice way to make the end plug go in and out forever without any need for lube and without ever damaging the o-rings (diamond chamfering helps but didn't fully solve the problem from what I tried). I just put the tube in the lathe, and torched the end for a minute or two and it, and it flared out adding probably 0.1" to the diameter (forgot to measure it, now it's all packed up for the flight home tomorrow). Just enough to let the o-ring not touch the glass as it first slides in, but be in full contact after sliding in an inch. As long as you do this to only one side it doesn't interfere with its use since you can always put the quick-coupling on from the other side. Although if it really bothers you to have it only single-side access on that, you can carve off the excess from the outside of the tube until it fits into the coupling. I did that on a few of my tubes then realized there's really no point and just left it after flaring.
I'll post back hopefully next week with how it's working, excited to use this with my feedback-regulated power supply and hopefully get a few million n/s at a stability that I can just sit back and activate stuff forever. Never really had good stability in my fusor.