Anisotropic Neutron Emission - Discussion

It may be difficult to separate "theory" from "application," but let''s see if this helps facilitate the discussion.
Post Reply
User avatar
Richard Hull
Moderator
Posts: 14991
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Anisotropic Neutron Emission - Discussion

Post by Richard Hull »

The historic, observational, reported physics of D-D fusion from the pros militates for generally isotropic neutron emission during all such fusions.

Reports of anisotropic neutron emission have been made in these forums.

I am worried that somewhat less than convincing data exists for this. Such issues fall back upon, what I perceive as, poor experimental controls. My issues with such reports are:

1. Most fusors are not completely stable over any long runs and, in general, not repeatable to sufficient accuracy over different runs with much the same level of operational parameters.
2. Instrumentation to warrant neutron measurement has been somewhat spotty due to.
a. Insensitive instrumentation, (lower inherent efficiency)
b. Not having enough collection time or data point numbers to make the data viable
3. The fusor, as commonly constructed, has more than enough protuberences, external attachments and nearby instrumentation that might just deflect enough neutrons to show measurable neutron "shadows" or zones of neutron paucity, should even good instrumentation be on hand.
4. Nearby items, furnature, walls, people, etc., can disturb what might be considered the "neutron field" under consideration via reflected, deflected or absorbed neutrons. (Basically, this is a failure to control the local environment)
5. Possibility of "zoning" of neutron production within the fusor in areas within the volume of the device. Neutrons produced in "hot zones" might be more or less affected by nearby chamber protuberences and constructional elements.

One fairly good report recently forwarded positing for neutron anisotropy worried me mostly related to points 3 and 4.

We are just too unsure of operations within the fusor and how various surroundings affect data taken to be able to rigidly control a number of key parameters and the environment. within and without the fusor.

Before long held professional results are to be questioned or refuted, better experimental controls on any anisotropy claim need to be inplace.

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
User avatar
Monroe Lee King Jr
Posts: 105
Joined: Thu Aug 22, 2013 11:57 pm
Real name: Monroe Lee King Jr
Location: Lampasas, Texas
Contact:

Re: Anisotropic Neutron Emission - Discussion

Post by Monroe Lee King Jr »

Bubble dosimetry may give you what your looking for if the fusor is contained inside the gel it could give you a better understanding of the radiation patterns due to the things you mentioned.

Monroe
Today's the Day! We go into Space!
User avatar
Richard Hull
Moderator
Posts: 14991
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Anisotropic Neutron Emission - Discussion

Post by Richard Hull »

What!! Dropping a fusor inside a vessel full of the bubble gel??! Ridiculous......and........it will never happen.

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
KJNW
Posts: 55
Joined: Thu Feb 18, 2010 12:32 am
Real name: Carl Greninger
Location: Federal Way Washingtojn
Contact:

Re: Anisotropic Neutron Emission - Discussion

Post by KJNW »

Hi Richard,

I am more than amused that you do not believe competent research can occur beyond your opinion regarding this subject. The students of the Northwest Nuclear Consortium have been coached with rigor during their design of experiment phase, and engineers from the Boeing Radiation Effects Lab, American Nuclear Society, Coalition for Plasma Sciences, Hanford and PNL have all reviewed and lauded their findings as well. Their entry on IEC Anisotropy won second place in the world at ISEF. I have personally mentored this team from the beginning, and am keenly aware of the issues. Let's cut to the chase. I have uploaded a link from the University of Wisconsin–Madison, Inertial Electrostatic Confinement Fusion web page below.

http://iec.neep.wisc.edu/usjapan/9th-US ... /Rusch.pdf
The closing line of this research reads; "Neutron rates were increased by as much as 30% when titanium was applied to the UW-IEC walls."

It has long been reported on this board that a prolonged operation of the fuser, without entering the vessel, will "condition" the system with the corresponding outcome that neutron rates are substantially increased, and that if the system is left at vacuum, the effect will continue to grow over time. Now certainly there is a substantial part of this "conditioning" that can be explained as the purging of foreign materials or outgassing of seals. But we have discovered that if we "pre-heat" our fuser in a high current glow mode with high D2 flow for a couple of hours prior to operation, there is a very big difference in the neutron output. At 60 KV we are approaching 3X10^6 output. Further, we can take an HE3 probe and simply pass it around the vessel, and quickly observe "hot-spots" that are well beyond what could be accounted for in normal scattering scenario's. These "hot-spots" represent neutron production in the first wall that corresponds to the 6 point pattern of the 3 hoop inner grid while in "star" mode and to the findings from the UW. Stainless steel is not an ideal material to imbed D2 ions in, but it works none the less, and is the source of the reported anisotropy in my opinion. We are now constructing a titanium inner grid that will serve to continually coat the chamber during operation. The downside is, we may use more gas in this scenario, but the increase in neutron production will be worth it. We will prepare a video over the weekend so you all may observe the phenomenon as it is VERY repeatable.

Carl - NWNC
Carl Greninger
North West Nuclear Consortium
http://www.NWNC.us.com
cgren@microsoft.com
User avatar
Chris Bradley
Posts: 2930
Joined: Fri May 02, 2008 7:05 am
Real name:

Re: Anisotropic Neutron Emission - Discussion

Post by Chris Bradley »

KJNW wrote:I am more than amused that you do not believe competent research can occur beyond your opinion regarding this subject.
Carl, not that I wish to be seen to defend Richard, for the simple reason that he is highly competent at doing that for himself!! But I don't think he was suggesting anything contrary to anything you've done/pitched/posited/&c.. Simply that putting a fusor in a big tub of neutron sensitive gel is arm-chair experimenting gone too far.

On the thread subject, I have been very clear with my conclusions from my work for some time now, which extend beyond fusor work itself. When I set about constructing my epicyclotron project, it was on the basis that the fusions were beam-gas. I am entirely satisfied that the reason I saw what I saw in those experiments was because fusor fusions are NOT from beam-gas, else I would have seen big positive neutron signals in my own device. What I actually saw was a lot of beam ion neutralisation going on instead. Loads of it. So much I began to wonder how the fusor pushes ions around at all, for any length of time. The conclusion was inevitable - it doesn't [that is, for very long]!

Putting 2-2 together, even though my epicyclotron project is not a fusor, I am confident it does say something about fusor fusion, which I am drawn to conclude is from fast-neutrals into the shell. As a fusor continues to operate, there is a build up of interstitial deuterium in the metal from those bombarding fast neutrals. Whatever metal is best at doing that, is therefore best at being a fusor shell. As the fast neutrals, generated in the beams, bombard the shell and build up this interstitial deuterium so the chances of more fusions goes up.

The probability of a fast neutral being formed in an ion/molecule/electron collision is some 8 to 10 Orders of Magnitude more likely than a fusion event. So the chances that an ion turns into a fast neutral and finds something to fuse with in the shell is considerably higher than an ion colliding with another ion or gas molecule in a fusing collision.

This is entirely consistent with your own observations and, again at fear of misinterpreting RIchard's position, I think Richard has expressed regard for my conclusions in the past, which therefore supports your own outcomes.

I'm pretty confident in my interpretation that the fusor is a device that does most of its fusion from a series of hot-spots in the shell (at the ends of the beams, which is exactly why the star mode is a precursor to fusion). If this is so, then anisotropy would therefore be assured, close up to a fusor.
KJNW
Posts: 55
Joined: Thu Feb 18, 2010 12:32 am
Real name: Carl Greninger
Location: Federal Way Washingtojn
Contact:

Re: Anisotropic Neutron Emission - Discussion

Post by KJNW »

Hi Chris,

If I have reacted to harshly towards Richard, it is only because I have worked seemlessly with three young fusioneer's for the last year in developing the most rigorously vetted experiments possible to bring an end to this question. Until now, I have kept my own theories to myself and let them drive the efffort, and now that you have done a better job of describing the phenomenon than I have, I shall continue to do so.

It was Richards remark; "Before long held professional results are to be questioned or refuted, better experimental controls on any anisotropy claim need to be in place."

That got my juices turning. We have a fuser that can run 100 minutes at a time hands-off. It is a bit like balancing a grape fruit on a picket fence, but our controls allow us the granularity to do it. If you don't believe that Richard just threw a bunch of well generalized cold water in the direction of our research on anisotropy, then I apologize. Otherwise, I am compelled to defend what has been recognized by a plethora of others as a well organized and carefully executed research project by these young people.

Image
Carl Greninger
North West Nuclear Consortium
http://www.NWNC.us.com
cgren@microsoft.com
User avatar
Monroe Lee King Jr
Posts: 105
Joined: Thu Aug 22, 2013 11:57 pm
Real name: Monroe Lee King Jr
Location: Lampasas, Texas
Contact:

Re: Anisotropic Neutron Emission - Discussion

Post by Monroe Lee King Jr »

Richard
??? Why? I'm just speculating indeed but wouldn't that give you a good idea of the radiation in a 3D view? Could you not determine from the pattern left in the gel exactly where the radiation is produced and what effects your chamber has on it?
What if I can reproduce the gel cheaply? Why wouldn't that work?

Monroe

if it's a heat problem can't the fusor be pulsed? Or does it require a long run to heat it up enough to produce the neutrons?
Today's the Day! We go into Space!
KJNW
Posts: 55
Joined: Thu Feb 18, 2010 12:32 am
Real name: Carl Greninger
Location: Federal Way Washingtojn
Contact:

Re: Anisotropic Neutron Emission - Discussion

Post by KJNW »

Hi Monroe,

Imagine surrounding the entire fusor with CR-39 chips. Then developing the chips in sodium hydroxide. Then reading the chips with digital processing. Then using a special mathematical software package that converts the data into a sphere. This was part of the project.
Image

Carl
Carl Greninger
North West Nuclear Consortium
http://www.NWNC.us.com
cgren@microsoft.com
User avatar
Chris Bradley
Posts: 2930
Joined: Fri May 02, 2008 7:05 am
Real name:

Re: Anisotropic Neutron Emission - Discussion

Post by Chris Bradley »

KJNW wrote:It was Richards remark; "Before long held professional results are to be questioned or refuted, better experimental controls on any anisotropy claim need to be in place." That got my juices turning.
I think you're talking crossed-purposes with Richard's point.

Some here were hinting towards their idea that it is the fusion itself that is acting anisotropically, not simply that a fusor produces neutrons anisotropically. Measuring anisotropic neutron field around a fusor is, as we are agreeing here, entirely plausible if you model isotropic neutron production at particular spots in the shell. I seem to recall at the time Richard made this thread, there were some claims that such observations meant the fusion collisions themselves were anisotropic without enough controls in place to discriminate these other possible effects/mechanisms.

The established wisdom is that fusion collisions emit their products randomly (unless the colliding particles are comparable in velocity to the product particles would be). Overturning that would be interesting, but would need a much higher standard [if not completely different form of] proof than simply showing anisotropy from a fusor.
KJNW
Posts: 55
Joined: Thu Feb 18, 2010 12:32 am
Real name: Carl Greninger
Location: Federal Way Washingtojn
Contact:

Re: Anisotropic Neutron Emission - Discussion

Post by KJNW »

I agree completely. Our research makes no such assertions.

Carl - NWNC
Carl Greninger
North West Nuclear Consortium
http://www.NWNC.us.com
cgren@microsoft.com
User avatar
Richard Hull
Moderator
Posts: 14991
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Anisotropic Neutron Emission - Discussion

Post by Richard Hull »

The issue of beam on target fusion in the fusor is real and can cause apparent hot spots, still isotropic, mind you, but appearing as multi-sourced neutron generators. (at the beam-wall junctures) I have noted before that coating a fusor interior with nickel, Titanium, or better still, paladium, would certainly dramatically impact the fusion numbers in a positive manner due to beam-on-target fusion adding to the far more mixed isotropic ion on ion gas collisons throughout the volume.

I have long posted many cold runs on Fusor IV here with full multi-run data that I positied were conditioning runs as in successive days, the runs got better and better as D was buried and remained hung in the walls when kept under vacuum between the frequent runs. SS and all metals suffer in a hydrogen environment and the energetic atoms will load into the crystalline matrix. (The very basis for the long suffering cold fusion work) Hydrogen embrillment is a very serious engineering issue in materials science and metallurgy, but for us, it is a boon.

I am actually undergoing this just now as I have run fusor IV for 12 runs over 12 days loading it up for the HEAS conference demo. The best run on day one was 42,000n/s, by the 4 th day's run, I was at 500,000 n/s and only last night hit 1.1mega n/s. This climb is not due to better vacuum or better techniques, but better wall loading I would warrant. This wall loading not only benefits beam-on-target fusion but also acts as a deuteron creation area at the wall via cook out and electron bombardment in the beam to enhance full energy deuteron arrival levels at the inner grid. (deuterons created at the ideal wall point) A double win.

As noted for some years here, the fusor operates on many levels that ARE doing fusion in many ways and places within it. It is so simple, the actual fusion methodology is complex and involves the entire volume and components.

In 1998 we noted that the fusor fused in the central grid star. By 2002 we had modified to the fact that it fused over the volume of the fusor and as early as 2006 we also added beam on target fusion. Our simple little fusor of 1998 got complicated and almost mystical in the number of fusion modality possibilities.

Chris got it right, I was commenting on the absurd idea of dipping a fusor in a bubble gel.

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
User avatar
Monroe Lee King Jr
Posts: 105
Joined: Thu Aug 22, 2013 11:57 pm
Real name: Monroe Lee King Jr
Location: Lampasas, Texas
Contact:

Re: Anisotropic Neutron Emission - Discussion

Post by Monroe Lee King Jr »

Oh I see you actually want to insult me eh?

lol whatever

Monroe

I like the direct approach I don't have time to play the guessing game.
Today's the Day! We go into Space!
User avatar
Monroe Lee King Jr
Posts: 105
Joined: Thu Aug 22, 2013 11:57 pm
Real name: Monroe Lee King Jr
Location: Lampasas, Texas
Contact:

Re: Anisotropic Neutron Emission - Discussion

Post by Monroe Lee King Jr »

KJNW

Ahh indeed thank you for letting me in on whats going on. Yes, that does sound like a pretty quantifiable analysis method to me! Humm can you direct me to more information about the project? Interesting.

I still like the hard evidence bubble Dosimetry could provide. I don't see the polymer development being impossible to recreate. I suppose you could divide a tank in half that you could close around the fusor perhaps acrylic. I just like a direct visible method that could be much cheaper.

Monroe

I know they do it for MRI's and other imaging equipment not for neutrons but x-rays and such. So why not for neutrons?
Today's the Day! We go into Space!
User avatar
Carl Willis
Posts: 2841
Joined: Thu Jul 26, 2001 7:33 pm
Real name: Carl Willis
Location: Albuquerque, New Mexico, USA
Contact:

Re: Anisotropic Neutron Emission - Discussion

Post by Carl Willis »

I'm glad the apparent confusion in this thread got sorted out.

To reiterate / summarize: When it's observed that the neutron field around a fusion apparatus is not symmetric, "anisotropy" (referring to the neutron-producing nuclear reaction) is very low on the list of explanations. According to the well-established measurements and theories pertaining to DD fusion, it's only really a plausible explanation in high-energy accelerator beam experiments, and most notably shows up when there are kinematic constraints on the product angle and energy distributions in some of the source reactions.

Likely causes for apparent neutron field asymmetry in hobby fusion projects are capture and scattering in surrounding materials, asymmetry in the source, inaccurate assumptions about the location of the source, and detector placement issues. All of these have just been competently discussed in this thread, and have been discussed previously. Jon Rosenstiel notably measured differences in the flux from a fusor that I was able to simulate through MCNP modeling of the stainless steel chamber.

Monroe: Carl's and his students' project has been discussed extensively in archived discussions and as soon as you get into those, you'll note he has a website as well. These existing resources should bring you up to speed on their project. I don't think anyone is out to insult you, but you've gotta realize that the credibility of some ideas--such as surrounding a fusor with a drop detector bath--can only be established through actual demonstration. I'm evidently not alone in doubting the practicality of this idea (for many reasons).

-Carl
Carl Willis
http://carlwillis.wordpress.com/
TEL: +1-505-412-3277
User avatar
Monroe Lee King Jr
Posts: 105
Joined: Thu Aug 22, 2013 11:57 pm
Real name: Monroe Lee King Jr
Location: Lampasas, Texas
Contact:

Re: Anisotropic Neutron Emission - Discussion

Post by Monroe Lee King Jr »

Ok Carl well I'm not there yet. When I get to making neutrons and feel the need for the bubble dosimeter I will find out if it's feasible for me to test. If the polymer turns out to be able to be recreated cheaply I will try it myself. It was a hypothetical solution albeit one I like.

Monroe

Does it take time for the fusor to come to equilibrium before it produces neutrons or can it be pulsed? Held evacuated and then pulsed again? Or does it have to be hot all the time?
Today's the Day! We go into Space!
JakeJHecla
Posts: 91
Joined: Fri Aug 26, 2011 6:19 pm
Real name:

Re: Anisotropic Neutron Emission - Discussion

Post by JakeJHecla »

Just to clarify, as someone who had a hand in designing this set of experiments, the hypothesis behind the apparent anisotropy was that we were seeing beam-on-target fusion in the walls, and therefore the field doesn't look like what we would expect from a point source in the poissor. We never suggested or intended to suggest the neutrons emitted from the D(d,n) reaction had a preferred direction! As a next step, I feel that measuring the neutron flux using the fusor assembly with an AmBe (or other) neutron source held where the grid would (with the unit obviously off!) be would be helpful. It would rule out any shielding or reflection issues, as we know in this case that the neutron source can be modeled as a pointlike emitter. If we see deviations from a uniform field consistent with our previous results, it's an external condition and our previous data is an artifact of external conditions. If not, then back to searching for the culprit.
User avatar
Richard Hull
Moderator
Posts: 14991
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Anisotropic Neutron Emission - Discussion

Post by Richard Hull »

No one has used a fusor successfully in pulse mode and reported back with a fusion "win". However, fusion should be very doable in pulsed mode.

Only a binned, calibrated, BTI bubble detector could be readily used in a manner that would be really acceptable at the amateur level here for quantitative work. The reason for this is that electronic counters would be very difficult to use due to their suseptability to EMP issues, pulse count separation, etc., and the difficulty in overcoming same in a credible manner. I have spoken of how a pulsed fusor might still use an electronic detection method in, now distant, past postings.

Pulsed work would have to be presented in a believable scenario with full voltage and current measurements in a time ordered manner, such as overlapping dual channel scope shots. It would be interesting work to poke around in, but most likely far less productive than a continuous run fusor, in amateur hands.

Current would lag voltage and significant, useful fusion would probably only be observed where the voltage was above 25kv, regardless of current. I would hope a 60kv peak voltage at discharge would be most successful. Richard Hester produced some interesting diagrams long ago using a hydrogen thyratron tube as the capacitor switch which is the desideratum due to its fast switch time, large current handling capability (1000's of amps) and ability to have a rather rapid duty cycle. (up to ~1000hz rate provided the joule rate capacity is not exceeded.) 60kv H2 thyratrons are very expensive. Custom spark gaps, while crude and limited could be fashioned by capable hands.

A more elegant and modern setup for pulsed work would involve IGBT switching of an H bridge into a custom oil bathed pulse transformer.

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
Richard Hester
Posts: 1519
Joined: Thu Jul 05, 2001 12:07 am
Real name:

Re: Anisotropic Neutron Emission - Discussion

Post by Richard Hester »

I was going to suggest a titanium vessel, but that would be prohibitively expensive and a perfect pain in the rear to fabricate. Coating the insides with Ti, as suggested earlier, is the easier route. Some bits and bobs from a Ti sublimation pump might be useful for such an attempt.

Later - I checked out the price of Ti Sublimation parts at Duniway, and boy are they expensive, even the replacement filaments. Seems they are a Mo-Ti alloy. Surplus/junk would be the way to go...
Post Reply

Return to “Fusor and/or General Fusion Theory (& FAQs)”