Coil Power Supply: Current Measurements

22 08 2011

All photos.

Today I took a step back and measured the current going through the coils.

Previously I measured 1,200 amps going through the coils with the capacitors charged to 450V.

My setup is a little different now: There are 2 meters of cabling + feedthrough between the coils and their power supply.

For all of these shots, the capacitors were charged to 450V. The shunt resistor shows 100mV across for 100A through. Multiply the voltage by 1000 to get the current in amps.

Surprisingly I’m seeing significant variation of current for identical conditions.

The most current I saw was 1,095 amps:

But with the same conditions I saw this much lower 344 amp current:

The median current reading was around 734 amps:

Disconnected, the coil shows 0.8 ohm of resistance.

I’m rather surprised by this variation. What could be the cause?

I tried some other conditions.

With the capacitors charged to 200V, I got 560 amps of current:

I also tried charging 5 out of 10 capacitors to 450V. With an average current of 500 amps.

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Deepest Potential Well Yet: 43 Volts

17 08 2011

All photos.

I’ve been running shots on the Polywell yesterday and today.

Just got my deepest potential well yet: 43 Volts.

10KV, 10mA on electron gun. 420V through coils. 8.5 millitorr air:

Be sure to check out the conditions I ran yesterday and today. Each shot has an oscilloscope photo with experimental parameters in caption.





Vacuum Degreasing

15 08 2011

All photos.

A vacuum specialist suggested a better technique for degreasing vacuum equipment:

Lightly swab with acetone, followed by reagent grade ethyl alcohol.

The acetone degreases, and the alcohol removes residual acetone.

 

I used this cleaning technique before reassembling the Polywell:

Back in the chamber soon!





Destroyed Coils

11 08 2011

All photos.

Today I removed the coils to inspect the damage from the last run.

Blown apart pretty good!

I’m attempting to clean the teflon in hydrochloric acid now.

The coils are easy enough to rewind.

There are little droplets of cooled molten copper inside the chamber!





Condition: Thinest Atmosphere Possible

7 08 2011

All photos.

My goal today was to find the thinest atmosphere that still creates a plasma.

The oscilloscope attached to the langmuir probe reveals this behavior transition around 8 millitorr:

Above 8 millitorr the plasma is relatively stable. As the pressure drops below 8 millitorr, the behavior transitions to extreme spikes in floating potential. The electron gun is at 25KV, current limited to 1mA.

This transition is not apparent from watching the plasma or power supply. New information!

As the pressure continues to drop, the spikes become less frequent and more extreme.

Until eventually I heard a rather loud pop…. which blew out the trigger circuit on my coil power supply!

I’ll have to repaire the coil power supply now. I must point out the bleed resistors did their job and slowly discharged the coil capacitors. Crucial safety feature.

So we learned something and I broke something. Good day.

UPDATE: A continuity test of the coil failed. The coil is damaged. The coil power supply is fine





Control: Fire the Coils Without Electron Beam

3 08 2011

In comments, chrismb suggested I fire the coils without the electron beam.

Great idea! This shows the effects of the coils alone… a control.

Results (same air pressure as before):

It seems the coils contribute a small positive voltage spike.

I did 3 test fires, all with similar results.





Sydney Experiment: We Have Electron Confinement!!!

2 08 2011

All photos.

1 year,  7 months  and 8 days ago I learned of the copper coil Polywell that Joe Khachan and his team built.

I decided to repeat Joe’s experiment. Although challenging it seemed possible to achieve. I dubbed this endeavor the Sydney Experiment.

It took far longer than I expected to fabricate all the necessary parts for the experiment.

Today with great pleasure I ran the Sydney Experiment. Here we see what appears to be electron confinement:

This acquisition shows the floating potential of the langmuir probe.

This run was done with air plasma at 10 millitorr :

The electron gun was running  10KvDC @ 6.5mA:

The coil power supply was charged to ~ 400VDC:

This is just a first run. Now begins the actual experimentation and data gathering.

I do believe this is the WORLD’S FIRST AMATEUR POLYWELL!!!

 

The plasma during the run:








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