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Anisotropic Neutron Emission - Discussion

Posted: Mon Sep 09, 2013 5:52 pm
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

Re: Anisotropic Neutron Emission - Discussion

Posted: Tue Sep 24, 2013 11:13 pm
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

Re: Anisotropic Neutron Emission - Discussion

Posted: Wed Sep 25, 2013 3:09 pm
by Richard Hull
What!! Dropping a fusor inside a vessel full of the bubble gel??! Ridiculous......and........it will never happen.

Richard Hull

Re: Anisotropic Neutron Emission - Discussion

Posted: Wed Sep 25, 2013 6:31 pm
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

Re: Anisotropic Neutron Emission - Discussion

Posted: Wed Sep 25, 2013 7:16 pm
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.

Re: Anisotropic Neutron Emission - Discussion

Posted: Wed Sep 25, 2013 8:13 pm
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

Re: Anisotropic Neutron Emission - Discussion

Posted: Wed Sep 25, 2013 8:30 pm
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?

Re: Anisotropic Neutron Emission - Discussion

Posted: Wed Sep 25, 2013 9:02 pm
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

Re: Anisotropic Neutron Emission - Discussion

Posted: Wed Sep 25, 2013 9:11 pm
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.

Re: Anisotropic Neutron Emission - Discussion

Posted: Wed Sep 25, 2013 9:19 pm
by KJNW
I agree completely. Our research makes no such assertions.

Carl - NWNC