Now that we have a working electron gun, the next challenge is to pulse the Polywell core while we shoot a beam of electrons into it. Trivial as it may sound, the hardest part of this is just getting all the components in the chamber aligned correctly and with electrical feed-throughs.
My previous e-gun armature was way too bulky, so I scraped it. After several different designs, I came to this:
The round base goes around the feed-through pins and fits snugly into the hole in the conflat:
The two screws visible in these pictures allow for adjustments to the distance between the anode and the cathode.
As for the cathode holder, I cut the filament off of a light bulb, and soldered it’s ends to two pieces of 12 gauge copper wire, each about an inch-long. I attached them to the feed-through pins with two crimp connectors. Not as a cool as a 3D printed holder, but much more compact, and no plastic to out-gas or melt from the heat of the filament.
Here’s the whole thing
Then we cleaned everything with acetone and ethyl alcohol.
Began the assembly. After much trial and error, I got everything in and aligned correctly, and got the vacuum down to about 8 x 10^-4 torr.
The only thing left to do is to hook up the Polywell power supply, so we’re pretty much ready for the run!