My fusor design with a lack of neutrons

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Andrew Seltzman
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Re: My fusor design with a lack of neutrons

Post by Andrew Seltzman »

For isolating the gap, having the ceramic overlap is usually sufficient. Using several nested ceramic tubes may be required to get the diameters correct, but this is usually ok.
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Dennis P Brown
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Re: My fusor design with a lack of neutrons

Post by Dennis P Brown »

Go to an auto parts store and get spark plug wire. They should sell rolls of it - most can handle at least 25 kV or more. That will reduce the corona issues. You could try placing the diode multiplier under oil - synthetic oil is excellent for that purpose.

How are you getting 20 kV? Have you got a new power supply? Again, I do not think that NST will get you clean signals - 4 counts/min over background (BG) isn't too strong a signal; however, if you make a run with no modulator and with, and get the excessive count (only with the modulator) then you are starting to make a case for the signal being real. Also, proving your background signal is a bit problematic - runs with a stable plasma for those time periods and making many runs (both BG, and then with and without modulator) will start to make your case. Getting reliable statistics with only 4 counts/min. above BG will be a challenge - especially with a limited supply of deuterium.

Your efforts and build are impressive.

Thanks for the translation. Didn't know that.
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Alexander Lichte
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Re: My fusor design with a lack of neutrons

Post by Alexander Lichte »

I am building a better HV power supply with my NST now.
I think you will be more satisfy with it.
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Dennis P Brown
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Re: My fusor design with a lack of neutrons

Post by Dennis P Brown »

What voltage are you using for your BF3 detector?
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Alexander Lichte
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Re: My fusor design with a lack of neutrons

Post by Alexander Lichte »

I use a Voltage Source adjustable from 300V - 1200V and a 8M2 Series resistor.
The detector current is adjusted to 5µA. The current is important for me. I do not know the real voltage at the detector.
But I do not have the 1600V from the data sheet. This is only necessary for a 100M Series resistor.
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Dennis P Brown
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Re: My fusor design with a lack of neutrons

Post by Dennis P Brown »

Thanks for that information; I have less then no knowledge on voltage variation allowances of BF3 detectors and have one. Wondering if below 1600 volts that is generally called for/normally used is an issue for detector performance? I ran mine at 1600 volts and got good results on neutrons signals but blew my counter after a while. So have given up on it.

In any case, I look forward to your post on your new higher voltage supply - obviously, might take some time.
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Richard Hull
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Re: My fusor design with a lack of neutrons

Post by Richard Hull »

BF3 tubes are typically far more immune to gamma rays than 3He tubes by a factor of a full order of magnitude! While both tubes are already highly immune, the BF3 in a good setup is usually "photon bullet proof".
Unfortunately, BF3 tubes in large sizes require 2800 volts or more to function. This can lead to coronal and oscillatory noise factors if fed by less than plus-ultra bias supplies or poorly wired home built BF3 detectors, connected by noisy cables and failure to terminate in characteristic impedances.

BF3 tubes do not require the huge pressures found in 3He tubes and are often filled to pressures at or just below atmosphere.

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Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Mark Rowley
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Re: My fusor design with a lack of neutrons

Post by Mark Rowley »

As evidenced with my system and the $150 Neutron Detector post (viewtopic.php?f=13&t=13216), I'll second what Richard is saying about BF3 detectors. Gamma, xray, and electrical noise blindness is excellent. If you elect to use an old Soviet 3He tube, expect it to be a headache when using it near an xray producing / electrically noisy fusor (as all fusors are). The Soviet 3He tubes are great for isotopic or static neutron sources like a fission reactor, Pu detection, Am/Be sources, and the like. But near a fusor you'll be registering a torrent of false counts from the noise.

Newer name brand 3He tubes from mainstream companies like LND seem to perform much better.

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Alexander Lichte
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Re: My fusor design with a lack of neutrons

Post by Alexander Lichte »

Nice to see your forum online again.
It was offline when I wanted to make the last post.

I've build a HV-cascade and it works fine.
There have been huge troubles with sparks:
There were sparks inside the reactor and these interfered with the neutron detector.
After all interference suppression measures were unsuccessful, I shielded the HV cable. This kept the interference away from the detector.
An iron powder choke in the HV supply line has significantly increased the stability of the gas discharge.

My setup:
Fusor_Vorderansicht_komplett.jpg
1: Backing pump
2: Diffusion pump
3: Throttle valve to the pump
4: 10 kV NST (NOT center-tapped)
5: HV Cascade, 10nF capacitors, went up to -35kV, 2mA@-25kV
5a: Washer as a field homogenizer
6: series resistor (transformer protection)
7: HV-Terminal
8: 200MOhm series resistor for voltage measurement (1:200 divider)
9: Shielding of the high voltage cable
10: Inductor with iron powder core in the HV-Cable:
Great EMI countermeasure!
11: Capacitive pressure gauge CMR275 Range: 0.1mBar
12: Spark gap as over voltage protection
13: CHM11 BF3 neutron detector with d=2.5cm Paraffin and some Plastic
14: Power source for neutron detector I=5µA
15: Red Pitaya as MCA for NaJ and n detector
16: Auto-transformer to adjust the HV

The D2 System is made completely new:
Fusor_Rueckansicht_Gaseinlass.jpg
1: PEM Cell
2: Pressure regulator for the PEM cell viewtopic.php?t=14483
3: Homemade needle valve
4: PEM Cell current
5: Throttle valve to the pump
6: ignition plug (extra insulated)
7: Shielding of the high voltage cable
8: HV-Voltage, 1:200 divider
9: HV current (3mA Range)

Yesterday I reached -26kV @ 2mA, Pressure: 16..18µBar:
Object-Name__000018__data_kl.jpg
I use a very solid steel wire d=0.8mm for the grid D=2.4cm (1 inch).
This gave me the highest dielectric strength.

I measure the neutron within 10 minutes - without / with moderator under the same conditions:
neutronen_gegenueberstellung.png
You can see approx. 1 neutron/min without moderator. That's the solar background radiation.
The first run was made one week before, with higher background.

With moderator, the count rate is always about a factor of 10 higher.

So I assume that this run released a significant number of neutrons.
There are not a lot of neutrons, but I'm sure Richard is right:
I need more power to achieve even more.
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Richard Hull
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Re: My fusor design with a lack of neutrons

Post by Richard Hull »

The image of the star tells me you are on the right track. You do need a bit more power, not much, however. Perhaps 5ma of current at close to 30kv then you should see many more neutrons. Really good work.

Question you should label the x and y Axis. I asume the x is in seconds? the Y is ????

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Alexander Lichte
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Re: My fusor design with a lack of neutrons

Post by Alexander Lichte »

Oh, Thank you for your praise!

I use a "red pitaya" as muti-cannel-analyzer:
http://pavel-demin.github.io/red-pitaya-notes/mcpha/
Many thanks to Pavel!

You can see a Histogram:
x-Axis: The Energy Level (in ADC counts)
y-Axis: The amount, how often this energy level was count.

Even if you cannot use it to measure the energy of the slow neutrons, the histogram gives indications when disturbances are affecting the measurement:
sparks_in_mca.png
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Dennis P Brown
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Re: My fusor design with a lack of neutrons

Post by Dennis P Brown »

You are running a bit on the low side relative to total power; certainly your neutron count shows that your device is clearly achieving fusion. The photo shows a blue plasma - this is due to your camera?
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Alexander Lichte
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Re: My fusor design with a lack of neutrons

Post by Alexander Lichte »

The color of the discharge is about right now.
The spectrum of the deuterium discharge consists mainly of the red 656nm D-α and the blue 486nm D-β line.
For me, the 486nm line is dominant.
For Liam David it is the 656nm line.
I don't know why.
Voltage - Current - Hydrogen Contamination?
To clarify this, I bought another spectrometer. But it hasn't arrived yet.
https://www.ebay.de/itm/143989529085
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Dennis P Brown
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Re: My fusor design with a lack of neutrons

Post by Dennis P Brown »

You are correct that the color varies. Appears that it turns out that both colors are generated but current density affects which dominates. LOL - didn't realize this fact. Follows with your lower current (2 ma) the bluer color occurs where as I have 30 ma and get the redder color (our cathodes both have 4Pi steradians of plasma discharge but only differ by available current supplied to the cathode.) See the discharge tube photo - both colors appear simultaneously but due to different current densities, the colors change depending on the tube diameter.
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Deuterium gas in fusor
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Deuterium Plasma Glow in Discharge Tube both colors
Deuterium Plasma Glow in Discharge Tube both colors
Matt_Gibson
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Re: My fusor design with a lack of neutrons

Post by Matt_Gibson »

You guys are lucky to see anything at all. My cathode glows so brightly that I can’t see anything at all. No star, no nothing. Looks like a light bulb.
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Alexander Lichte
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Re: My fusor design with a lack of neutrons

Post by Alexander Lichte »

Hello Dennis, your pictures are interesting - great!

Even if my primary goal is to gain experience for future LENR experiments, I would be delighted to be accepted into your legendary club.

@Andrew: Don't use cameras with autofocus and other automatisms: These are too confused by the plasma.
I use an astro camera with a 35mm lens.
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