Fusor Forums

Does anyone have a low-cost source for Cu or Cu/Be in-vacuum electrical connectors used for stalks and other feedthrough assemblies? I'm looking for something similar to Cermatec barrel-with-set-screw type connectors, ideally without the megabucks cost? Even vacuum compatible compression or set screw connectors would do the trick.

Years ago we made our own connectors for connecting wires and posts on ion sources. We cut pieces of 1/8" OD stainless tubing, drilled and tapped (0-80) a hole about 1/8" from each end, and put in 0-80 x 1/8" pan head screws. We used pan head screws rather than set screws because it was easy to lose the set screws. This was the standard type connector used in those days. You could buy them, but it was cheaper to make them. If you need to connect to larger rods (e.g. feedthrough conductors) you can use 1/4" OD tubing.

It seems like this is almost always going to be screws and nuts for the low-budget.


Accu-Glass has many options including circular "C-sub" connectors for multi-pin instrumentation and larger pin-and-sleeve connectors. However they are dear.


If you are OK with brass in your chamber, you have many options. My strategy is to buy the appropriate size of Euro-style terminal block strip like this: https://www.allelectronics.com/item/tb- ... ock/1.html and then to carefully cut away all the plastic.

One can then replace the slotted screws with socket-head set screws and have an excellent connector.


Another thing worth considering is the "bullet" or bannana style connectors used for high current connections in the world of R/C cars, planes, and drones. I don't know the exact material -- something copper alloy ish with gold or fake gold plating.

I am interested if anyone has gone the route of the Banana connectors if they would be willing to share their expertise.
Otherwise, we'll have to go the route Dan suggests with a 1/8" O.D. steel tube.

Our fusor will have a 2.75" CF HV feedthrough flange. There are two connections for two input wires. On the inside, these two connections run parallel for about 1 cm (ceramic insulated) and both terminate as a screw thread + hex nut (exposed). Unfortunately I do not have a photo.

Our plan is to build a demo fusor, testing various internal grid geometries (pyramid, cube, sphere, etc.), so it would be advantageous to have a ceramic insulated stalk lead to the center of the spherical chamber, and at the end of the stalk have a female banana jack connection.

Then changing the grid shape is as easy as plug and play with a male banana connector. Any tips?

Banana hardware is usually plated brass, which is not a good material to use in vacuum, especially if if gets hot. The other problem with banana connectors is that they are "spring" fit. The plugs will lose their "spring" when hot and the connection will fail. One can buy spring connectors from vacuum suppliers, but they are expensive. Threaded or crimped connectors are your best bet.