Symmetry Test

27 07 2012

All photos

This project is moving into a new phase. Now that we have a working electron gun/polywell setup, it’s time to begin studying the way they interact. To do this, we need a more comprehensive measurement apparatus.

In light of last week’s murky trial results, It’s apparent that a single langmuir probe in the center of our polywell core does not give us a clear picture of the whole well. I think a good first step would be to try to understand how the differs at different distances from the center.

In other words, how is the well different at different points on the red line?

Before I try to answer this question,  I want to make sure that each of the six coils behaves in more or less the same way. In other words, I want to make sure  If the red line above was pointing in the direction of the left coil instead of the right one, it would made no difference. I’m going to call this a symmetry test, because it will reveal whether or not the well is electromagnetically “symmetrical” about the x, y and z axes.

The symmetry test will work like this: Two more langmuir probes into the core, one on the extreme right of the chamber, and the other at the extreme left.

Right Langmuir

Left Langmuir

If our oscilloscope readings from the two probes are the same, then we may safely assume that the faces are interchangeable.

We’re rapidly running out of feedthrough pins

Core, from the right.

I can’t imagine that the thing’s not symmetrical, because the construction of each coil is identical to that of all others. However, thoroughness never hurt anybody. Also, I’m going to leave the center probe in, so we will be able to compare the center of the well to the edge, which will be interesting in its own right.

Domenick Bauer


16 07 2010

All Photos.

TV Asahi did a report from the lab:

We received the final ceramic for the Langmuir probe. It fits a little loose, but I think it will do.

Finally got a new drill… I’ve been borrowing my shop mate’s!

I started to explore the gas type calibration on the ion gauge. Until now it’s been set to air. But now we are running a deuterium atmosphere, so I tried setting the gauge to D2:


We saw the following difference in reading:

So 10 millitorr on the air setting is equilivent to 29 millitor on the deuterium setting. Big difference.

The lower pressure threshold to strike a plasma is ~20 millitoor in deuterium mode.


So it was noted on the fusor forums that I’m getting about 10% of the fusion I should be for the power going in. This is likely due to a leak or other contaminant in the chamber. Carl Willis suggested I drop rubbing alcohol into each gasket individually and check for a change in plasma color (hydrocarbons glow a steel gray compared to the purple of the deuterium plasma).I took a first stab at this but didn’t see any color changes. Here is a dropper of alcohol:

I also got a mirror for safer viewing of the plasma (the mirror does not reflect xrays):

Speaking of safety, I have a meeting with Dept of Health’s Dr.Karam. He’s a scientist and he sounds genuinely interested in the project. A radiation specialist, he is bringing a wide array of detectors to get a full profile of our radiation output. Should be really educational. Looking forward to it.

And finally I had lunch at Google NYC the other day:

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