Worlds smallest Fusor.

[TannerOates]

Hello, for about 6 months now I have been working on a new fusor project. This project is aimed at being completely computer controlled (in respect to D2 flow, vacuum, voltage applied.) and of course being the worlds smallest. The main chamber of this reactor is 1 1/3" inches across, about half the size of the Chad Ramey's current 2.75" reactor. My design works off of a di-hemisphere compressible grid making it possible to have a large confinement area in relation to chamber size. This grid design allows the reactor to function on both AC and DC current, making it extremely versatile. The construction is complete stainless steel with the only viewport being made of thick lead glass. At -50kv@7.5ma there were no x-rays detected out of the chamber, which means it is safe to view in demo mode at high voltages. Due to the extremely small size of the reactor, at moderate voltages (-15kv@5ma) plasma extinguishes at around 100mbar. I will be attempting fusion this coming weekend and detecting neutrons with a victoreen 488a meter. I also will be doing a more in depth write up of the reactor at this time as well.

The first image is a DC -25kv@6ma plasma and the second is the reactor in hand. Let it be noted I will be adding a 2179a MKS flow meter to the chamber which will increase its size on the z-axis slightly.

Any technical comments and questions are always welcome.

[Tyler Christensen]

Looks nice. What instrument did you use to determine that there is no x-ray leakage at 50kv? Even 1/8" thick stainless usually starts leaking x-rays at 50kv, I find it unlikely that much thinner wall hardware used in 1.33 fittings wouldn't have pretty substantial leakage at that voltage.

Tyler

[TannerOates]

I used a monitor-4 counter, which I have confirmed to be an adequate x-ray detector. The fittings are quite thick, the smallest being 1/4" thick blank flange.

[Richard Hull]

A more complete exposition of images from all angles would be nice. How did you get 50kv into that tiny thing!!??

No x-rays! I am with Tyler on that one.... If the item is in any cross or any fitting that is thin, x-rays will pour out and come on like gang busters at 50kv 7.5ma.

Just saying.... based on 15 years of playing with this stuff.

Richard Hull

[TannerOates]

Again, I will do a more complete write up after I attempt fusion this coming weekend. Proper grounding and an adequate power source. Yes, there is a moderately thin part on the side but there is no 'line of sight' thin path to the x-ray source. I have done detection on the entire body of the reactor and found no x-rays, I will try again with another detector to double and triple check.


What is the best path to register this as worlds smallest besides for GWR(which I am waiting on).

Thanks again!

[chad ramey]

Looks great! Made any neutrons from it yet?

-Chad

[TannerOates]

Thanks! Im going for fusion this weekend.

[tbogusiak]

Dang, that's the same size chamber I'm planning on using, you beat me to it.
As for the X-rays, the 1.33" conflat cubes are made out of a solid block of stainless (I have no clue how they machine out a sphere inside it though), the THINNEST sections are about 5mm thick, you can sort of see the thick shell around the ports on my little cube. Congrats on a fine looking fusor


It'd take a bit of voltage to push a decent quantity of X-rays through those walls

[Roberto Ferrari]

Hello
Is a beautiful setup but I am still waiting for the answer to Richard'question:
" How did you get 50kv into that tiny thing!!??"

Regards

Roberto

[TannerOates]

I already answered it. I used an adequate power supply and safe grounding. If the pressure gets too low it will arc, but aside from that, it is very stable.

[George Dowell]

The Monitor 4 does not have a GM tube saturation feature, neither does Ludlum Model 3 etc.

A GM tube when overloaded, will simply saturate, the meter will read zero CPM.

IF you MUST use a GM tube for X-Rays at least use something like an AWARE meter, which will not saturate with the same tube that other meters will. Yes I know some think otherwise, but it's true.

The proper X-Ray detector is of course an intergrating ion chamber, with a thin entrance window.

End of that discussion.


George Dowell

[Chris Bradley]

TannerOates wrote:
> If the pressure gets too low it will arc, but aside from that, it is very stable.
I regret, that this makes no sense to me.

This would rather seem to imply you are not seeing 50 kV at the actual electrodes. When a plasma strikes the voltage will get pulled down in an unregulated supply (or even a regulated one without enough 'guts' to push the power out!). The only reason I can think of for arcing when the plasma extinguishes is that the voltage has ramped up because the supply is soft and has recovered to the nominal voltage.

A small volume becomes extremely high impedance at low pressure, because you get well beyond the left of those 'up-strokes' in the Paschen pd breakdown diagram as the 'd' get very small. So you should get less arcing, not more, unless the voltage has shot up as the plasma extinguishes.

What's your power supply?

[Rich Feldman]

TannerOates wrote:
> What is the best path to register this as worlds smallest besides for GWR(which I am waiting on).
Do you mean, the smallest "fusor" which has been brought to the attention of the fusor.net club?
Have you ever registered a star name for yourself or a loved one?

What is GWR?
Can't find anything that makes sense on...
http://en.wikipedia.org/wiki/GWR
http://www.acronymattic.com/GWR.html
http://www.all-acronyms.com/cat/0/GWR
http://www.abbreviations.com/GWR
http://abbreviations.wordcrow.com/define/GWR/
http://www.gaarde.org/acronyms/?lookup=GWR
God's Waiting Room? I guess every person of faith gets there soon enough.

[TannerOates]

A glassman ml series

[TannerOates]

Haha, guinness world records? I guess we are all in god's waiting room haha!

[Chris Bradley]

So, this would appear to be the ML40N07.5 model? 40 kV / 7.5 mA?

http://www.glassmanhv.com/PDFs/ML_Series.pdf

I'm wondering what its voltage characteristics are with a load impedance that draws more than the 7.5 mA rated output. How are you monitoring volts and current? Even though it is a regulated supply, if you try to draw more current than it is rated to deliver, the voltage regulation will not be able to meet the rated voltage.

[Richard Hull]

I believe this significant claim is being handled in the images du jour in an archived report. Tanner says he is attempting to meter voltage, current and pressure and report to an acceptable level. We are waiting for this effort to generate a better and more complete report acceptable to critical review.

Richard Hull

[TannerOates]

Yes, I believe that is it. I will confirm when I am near the unit tonight. Will Jack sent me the manual for this series glassman to make a controller, I seem to have misplaced them. Would anybody on here have access to these documents and a scanner? Thanks.