Construction of Neutron Grade Fusor

[Enzo Carter]

I have made demo fusor out of glass then from metal (when i burnt the cathode) then made the setup turbo friendly then upgraded from a 30kV a 70kV power supply then added a deuterium tank and after that added neutron counters. Now its time to document my neutron grade build because I think I have a good enough setup.

All work being done at the University of our House - UoH. operation of HV restricted to supervision. handling of anything liberating energy randomly restricted to supervision.

most items originally sourced from ebay, then borrowed from the University. i have had to pay for some items that we could not get from UoH stock like a NW50 to iso100 for the turbo at 75 dollars.

Roughing Pump
Edwards two stage E2M5
Best pressure 38mT isolated. leaky but quietish

Leybold Turbo Pump
Model TW250S
+control

Varian screw valve
NW50 to NW50

Vacuum chamber
4-way NW 50 cross - stainless

view port
NW-50 view port

Granville Phillips Vacuum gauge
Foreline Pirani-275 mini-convectron

cathode
1-stainless sphere wound using acrylic rod
2-nickle with 8 holes and tungsten rods so more melt proof

High Voltage feedthrough
25kV rated
50kV tested
3.6mm shaft

Spellman Power Supply -70kV 8.56 mA
DXM70N600X3547

high voltagfe control panel
in home made

High voltage wire
40kV 22awg

Ballast resistor
100k Ohms 100W

Fluke 80K-40 40kV high voltage probe

Gammaspectacular GS-Neutron
Neutron Detector - modified for moderator removal

to
Rigol DS1054 Scope as discriminator and for neutron visuals

t0
HP 5334A Universal Counter

Deuterium bottle (ebay) 50mm x 230mm
charged to 15psi from 5L deuterium lecture bottle @ 1500psi
with two needle valves from ace hardware sscrounging

several cameras.
gopro
iphone
plcmDvr72 7 inch screen and dual recorsing camea set from amazon

Custom 1/4 inch acrylic high voltage screen
laser cut in garage

moderators
hdpe blocks from ebay 50mm x 150mm x 110mm
gulf wax blocks 60mm x 80mm x 80mm
gs-neutron 90mm diameter 40mm from tube to outside - looks like black hdpe

i have been doing runs for a few weeks now and am getting close to something to show to the forum. safety is key so i have not been able to work unsupervised which limits my reactor time

this is hard for me in many ways as I think and talk fast but type slow.

its ten parts research to one part lab

i will say that what Richard says is so true; keeping the plasma lit and controlling pressure to work up the voltage is less science and ,more art. This is hard even with the expert help and support from this forum and my family. thank you.

[Richard Hull]

Great effort. Keep up the good work. You will get there, I am sure.
Patience is not highly valued in the excitement of youthful bravado, but is part of what a good scientist and researcher needs to succeed.

Richard Hull

[Enzo Carter]

I have a neutron run I would like to document here. The run was on 1/11/19 and it took me this long to put together the data as it is a slow process.

i have data, picturs, and some cute video

setup;
The hardware is listed above.

We took the roughing pump to bring the chanber down to 100 microns. Then we turned on the turbo to suck it down to well below the gauge minimum of 1 micron. likely 10-5 or -6.

Then we shut the NW50 valve to almost closed. closed minus just a fraction of a turn

after that we let in a little gas then we shut the gas valve so it wouldnt raise the chamber pressure too much. Now we a chamber with deuterium gas in it at 100 to 300 microns.

Then we light the cathode and the pressure jumps up and arcs out the supply. so we open the NW50 a little more and keep lighting the palsma as the pressure drops.

note the plasma lighting raises the pressure in the vacuum chamber quickly and if does that for any amout of time keeps us above the target prssure

It is a very long and tedius process to get the cathode nice for fusion as it needs to be pre-heated to be good for plasma.

Because our power supply only goes to 8mA its a constant push button start, arc out, push button start to keep it running. We get short stable runs of 1-3 seconds of stable plasma which is enough to seperate neutrons from noise.

It took three nights to get this run and capture it on video and in data all at once. much harder than it would seem.

Enzos Neutron Run
1/11/19

Nickel + Tungsten-rod cathode
13.5kV
57 mT / 48mT
Spellman DXM -70K Supply

About 1 second intervals
22 N/s @13.5kV @57mT
0 N/s @13.5kV @57mT (tube removed from moderator)
0 N/s @13.5kV @57mT (tube removed from moderator)
0 N/s @13.5kV @57mT (tube removed from moderator)
13 N/s @13.5kV @57mT
10 N/s @13.5kV @47mT
0 N/s @13.5kV @45mT (tube removed from moderator)
0 N/s @13.5kV @46mT (tube removed from moderator)
0 N/s @13.5kV @47mT (tube removed from moderator)
37 N/s @14kV @48mT

Average Neutrons/sec with moderator 15
Average neutrons/sec without moderator 0

Screen shot from xls is easier to read

This data is visible in this video: I think in the video I explain what is going on pretty well. If something isnt clear pease ask I will definitely answer it for you
https://youtu.be/nCGECKeXrpI

I have a lot of data on pumpdown times, fusor pressure leakage, and xrays testing i did. I dont think its really relevant to this run. But I will post it when I can figure out how to make graphs better.

Here is the picture of the cathode

As always i would like to thank fusor.net for all of the constructive support. I could not have done this without you. I think there is a very big difference between going to the library and getting a book on fusion. This forum is like 100 libraries filled with fusion books written by people who have actually handled the material and done or tried to do fusion.

Enzo

[Dennis P Brown]

The 13-14 kV and a maximum of just 8 ma is not a voltage/power that generally yields many neutrons in most fusor systems (generally, 200 watts power is a better goal.) However, the high pressure can compensate in a small chamber for lower voltages but that is extremely low operating voltage/power.

Since your plasma isn't under control (creating emf bursts) that can lead to issues in electronics via ground loops and/or emf shielding issues in detectors/line/powers cables/lower voltage supplies. Not saying it did, just it can. Your unstable plasma is a concern; hence I understand your getting one second data readings with the varying voltages/pressures. This type of system/data readings can cause issues for accurate data collection. If such is the case, neutron data might be due to emf issues (yes, I see you measured no mod but your total data runs and neutron level isn't necessarily enough to provide clean data) - hence, only a few short runs isn't very reliable data (necessarily.) The high pressure can cause issues with stability in a fusor - most people find 5 to 15 microns a far more steady operating region and allows higher voltages to be sustained.

Also, you should not average counts with runs done at different voltages and pressures - that isn't good technique for data reduction. You say it took three days to get these results. Again, if the data is taken with substantially different time frames or different runs, again, the data should be handle separately and not average together. Not mandatory but good practice - certainly, flag the data runs with their associated time stamps.

You may be getting real counts but I am not certain. Others with more experience will, I am sure, give further, and no doubt, better advice. Still, I would suggest much longer runs and hold the parameters more steady before averaging data. Certainly, a higher voltage like 20 kV would give more clear results so you should consider a lower system pressure - that might allow a higher voltage and more stable plasma. Even then, the net power is extremely low (assuming your getting the full 8 ma.) You should consider, if possible (but not needed) measuring the current.

A good beginning and hope you continue to get better results.

[Joe Gayo]

Spellman's DXM and SLM are built on the same platform and with several component changes and firmware you can convert one to the other. The lack of constant current and voltage fold-back with the DXM version makes stable operation with a plasma very challenging. You have a couple of options:

- Contact Spellman (Cliff S.) and get instructions to convert your DXM to a SLM
- Increase your ballast resistor substantially which will reduce the max cathode voltage but also make control easier
- Add an ion source to stabilize operation (viewtopic.php?f=12&t=5011)
- Risky Option: replace the driver board with an unregulated half bridge and power with a variac for voltage control (you need to use the feedback connector to measure the output voltage and current viewtopic.php?f=11&t=11146)

I'm not judge or jury for the neutron club, but stable higher power/voltage operation will help your case.

[Bob Reite]

Since you have a 70KV supply I would increase your ballast resistor to 2.5 megohms! Yes, that's 2,500,000 ohms. Assuming that you are drawing 8 mA, that in theory should drop only 20 KV across the resistor leaving 50 KV across the fusor, assuming that your supply does put out an honest 70 KV at 8 mA. Yes, the resistor will have to dissipate 160 watts. With that much voltage dropped across the resistor it would be best to make it out of several resistors in series.

This will make the supply behave more like a constant current source and be more controllable.

[Richard Hull]

All of the foregoing is good advice. Get a stable plasma for more than a minute above 25 kv and at a pressure of about 5-20mT and that is where you are going to see early fusion results. Burst of neutrons are more likely bursts of RF pulses into the detector.

Again, what is your detection method. I would hate to claim fusion results at 13.5kv even with my big 3He tube you are still in a statistics battle and this would be with a perfectly controlled 10 minute stable smooth plasma.

You have a ways to go yet.

Richard Hull

[Rex Allers]

Enzo,

I just posted this in another thread
viewtopic.php?f=6&t=12441&start=20#p82045

The other young person I mentioned is you, so what I said applies to you too.

Very nice to see some young people deep into technology and science. Real physical, measurable stuff. Good to know not all are stuck in the world of their phones.

[Enzo Carter]

Since you have a 70KV supply I would increase your ballast resistor to 2.5 megohms! Yes, that's 2,500,000 ohms...

I didn't have a ballast resistor that big but, I did have a couple smaller ones so I pieced together 163,000 omhs and shorting out was less commen.

Thanks for the export advice.

[Enzo Carter]

...
- Increase your ballast resistor substantially which will reduce the max cathode voltage but also make control easier
- Add an ion source to stabilize operation (viewtopic.php?f=12&t=5011)
...

Thanks for the suggestions. I added an ion source from fellow fusor member Andrew S. and now my plasma stays on much easier and at lower pressures allowing higher voltages.

Also added as much ballast as I could. It also helped.

its not firing directly at my cathode because of the NW50 lengths I have to work from, but it grazes it.

side view of ion source installed

side view of cathode as viewed by ion source

looks like a hamster was living in my NW50. Its nuclear fallout