SCR Upgrade

28 10 2011

All photos.

I received the new SCR. It can handle 3000 amps peak current. It is much larger than the SCR I recently destroyed:

IRKT136-14 data sheet.

Here it is installed. Everything works:

I also added leads to the current sense resistor to avoid touching the back of the power supply:

The pressure necessary for plasma is still too high. I tried another tweak to the electron gun:

No joy. It requires about 24 millitorr for a stable plasma. UG.

LIFT Conference

23 10 2011

I will be giving a talk at the LIFT conference in Geneva in February 2012!

Mark Suppes is a extreme amateur! He is the member of a growing community of “fusioneers” – amateur science junkies who are building homemade fusion reactors, for fun and with an eye to being part of the solution to that problem. Mark is the 38th independent amateur physicist in the world to achieve nuclear fusion from a homemade reactor.

Lift12 first confirmed speakers!

Electron Gun Tweaks

20 10 2011

All photos.

Today I tweaked the electron gun.

My goal is to bring the electron gun closer to ground. This should reduce the pressure needed to strike a plasma.

I used Stuart’s DIY spot welder to make a hoop from welding wire:

I installed this hoop on the electron gun:

This arrangement brings ground potential closer to the electron gun.

And it worked somewhat.

With this hoop, I can strike a stable plasma at 18 millatorr. Better than yesterday’s 25 millatorr. Still needs work to get back to 8.5 millatorr.

When I went to fire the coils I discovered my SCR is shot:

Turns out the SCR’s peak current is 2,000 amps. At 2,300 amps we are well beyond that!

I have to order a new SCR tonight. Suggestions welcome.

Elsewhere… I drilled a hole in the langmuir probe holder to allow trapped gas to escape:

Also tested out the supercapacitors in my friend Arnie’s forklift:

They were able to lift Arnie twice!

Video of operation:

Supercapacitors are Super

19 10 2011

All photos.

Electric double-layer capacitors are a newish energy storage technology. I find them fascinating and I want to play with them.

Like a capacitor they can charge and discharge very quickly due to their low equivalent series resistance.

But supercapacitors store roughly two orders of magnitude more energy than normal capacitors!

I bought five 3000 farad, 2.7V Boostcaps:

3000 farad!

I machined aluminum strips to form connecting bars. A 13.5 V series stack:

Check out this video of a full-charge short circuit:

Test Shots

18 10 2011

All photos.

Today I wired up the Polywell.

I made an armature to accomodate the new high voltage probe:

I tested the coils: definitely hitting 2.3 kA, which is what we want.

But when I tested the electron gun I saw a problem: It needs 25 millitorr of air to strike a plasma, up from the 8.5 millitorr of the original configuration. This is a problem because high pressure reduces potential well formation.

I was able to take some test shots… everything is working. The potential wells are shallow due to the high pressure.

Here you see the current on channel 1 (the bump that goes up) with a peak of 800A. The potential well is on channel 2 (bump that goes down) with a peak of -8V. For current in amps, multiply by 1000. For potential well in volts multiply by 1000.

New High Voltage Probe

18 10 2011

Just got this Tektronix P6015 high voltage probe. It goes up to 40 kV!

Well actually it only goes to 27 kV without the fluorocarbon 114 dielectric.

It’s huge! Shown next to a normal probe:

Just in time for the next run.

This is the same probe used in the Sydney experiment.

Ready for Next Run

17 10 2011

All photos.

I’ve been working towards re-running the Sydney experiment with 2.3 kA of current through the coils. This required completely re-arranging the pieces of the experiment.

A big change was moving the langmuir probe to the same flange as the coils for better alignment.

I’ve been waiting for two weeks for this part from shapeways (thingaverse). It’s a new holder for the langmuir probe:

It holds a ceramic tube like so:

Now the probe is always nicely centered:

I cut down the electron gun for the new arrangement:

I made new ceramic standoffs because the previous ones were poorly crafted. These ones turned out nicely:

Here you can see the electron gun on the left and coils in the center:

I buttoned everything up:

I got the vacuum down to 1.1 millitorr. Not great, but good enough for this experiment.

Tomorrow I will wire up the electrical and run the sydney experiment at full power.

From CRT to Electron Gun

6 10 2011

This post is dedicated to Steve Jobs. Hero, and inspiration to all.

All photos.

I bought a second CRT; broke the vacuum by drilling an unused pin; scored it and smashed it!

Now we have an electron gun:

I installed it in the chamber and wired it up:

Here you can see down the beam line to the hot cathode.

I taped a piece of broken phosphor screen on the viewport so I can see the electron beam:

But something is not working, no beam.

Time to troubleshoot.

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