Fusor Forums

Hello all!

As some of you may remember, not too long ago I made a post about the state of my reactor. Now, two weeks later, I'm ready to post my updates. In this post I'd like to share my progress as well as ask a few questions. Here's the link to the first post: viewtopic.php?f=6&t=11527.

Here's a picture of the entire setup and an incredibly basic diagram:
The most obvious change with the setup is the new electrical feedthrough:
The biggest modification made though, was at the back of the reactor:
Previously, it was closed off with a blank cap, but now it's taken from Cf35 down to 1/4 through a series of reducers and adapters. The reason for this is so I have place to connect the deuterium line as well as the thermocouple gauge. As of now, the ports are closed off with caps (such as the brass piece at the end of the reactor.

I also purchased some high voltage (40kv) wire:
You can see in some of the pictures I've used it to connect the reactor to the power supply.

I also purchased brand new copper gaskets for the reactor, as the original ones I had been using were sold to me used. I should have noticed, but it got past me.

The last major update made was the grid:
It's made of .031" thick tantalum wire which is clamped onto the feedthrough with 1/4" SS pipe. Along with these updates, I cleaned all of the parts that where to be exposed to vacuum with acetone and then 91% isopropyl alcohol to remove remaining acetone.

However, there is one issue:
The grid won't light up. The very first time I turned the reactor on with it;s new upgrades it was fine, unless you count the fact the plasma wasn't confined in the center as I hoped it would. Then, the plasma slowly began to extinguish on the grid. It continued until there was absolutely none on the actual grid, but all on the SS pipe, as you can see in the picture. Why is this? I've been looking all over, and the only two explanations I can find are that the pressure is too low (which I doubt since it isn't confined in the middle) or there isn't enough "fuel". I take "fuel" to be power as in watts, which is believable I suppose. Thank you for your time!

Thank you for all the suggestions on the first post, they helped inspire some of the updates done.

The issue of your plasma not becoming centrally confined within the grid can be fixed by using a ceramic (usually alumina) tube to cover the stainless steel pipe.
Check McMaster Carr
Of course power and pressure are important in determining whether or not you will have a good plasma. Most likely the "fuel" had to do with pressure as well.

Regards,
-Matthew

Looks like your pressure is far too high to be getting any confined plasma, fix this and you will get much better results. You should get a vacuum gauge to determine what is actually happening within your chamber. From there you can perform leak tests and figure out where your leak is.

Regards,
Sam

Way ahead of you. I'm currently waiting for the last part I need to attach my thermocouple Gauge. The vacuum is probably pretty weak do to the used copper gasket on the electrical feedthrough. This is in case the grid fails (which it did) I won't have to use another copper gasket. I have a viton one in the mail.