Why IEC fusors can't work

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Why IEC fusors can't work

Postby Doug Coulter » Tue Jan 25, 2011 12:10 pm

There's a provocative title for you. We are attempting the impossible, so either this guy has to be wrong, or we have to be more right than he, and more subtle/clever.
Critique.pdf
Rider critique
(2.21 MiB) Downloaded 245 times


A longer version (his thesis) is here. Warning, it's 18 megabytes. Don't you hate people who just scan in PDF's so they are a long series of images instead of the much more compact original form?

Reading these, as ChrisB and I both have, I think leads well into a discussion of why we think our approaches aren't silly -- we both address the issues described here in our own ways, and I'm convinced that any successful other plan will have to also. I believe that someone calculated that for a straight Farnsworth fusor you need recirculation on the order of 7000 times before an ion is lost to get to gain. I'm sure not seeing that in any tests here, or even close, the time that would take to die off after an ion source would show easily on my gear, and I see very fast shutdown -- perhaps one or two transit times of the ions at the expected energies (and I have hints that the actual energies are much less than expected from oversimple analysis).

However, while this guy is good, he's not perfect either, and not everything he says is quite right. Not that his errors necessarily work in our favor, but it's encouraging that even an amateur can also pick some of his points apart.

For example, to get the ball rolling, Fig 1-1 on page 8 of the attachment is somewhere between wrong and dead wrong, as it ignores the charge on the ions affecting the potential well, and in actual conditions, it may cancel it completely! So we begin right off with a failure to take the reality of the real system into account (not uncommon for academics). Further, the potential well inside a grid is not like that created by a point electrode in the middle -- it has a more complex shape than that. It's not just me saying that one -- many schemes try to keep some electrons around to prevent this (think plain old plasmas) which then become tokomak-like things, which then fall afoul of thermalization, or the spreading out of the ion energy/motion vectors into all degrees of freedom, which kinda wastes most of the input energy on that.

I'll have some more as I re-read these (good to go back once in awhile) but here I'm just getting a ball rolling so we can have "many eyes" looking at this. Large as it is, it's the most compact and complete list of the issues we have in the library (I think).

So have at, people -- this is the real thing we're trying to learn to overcome with various schemes, the things our inventions have to handle in one way or another if we want to have hope of gain -- or even a very nifty neutron source capable of breeding fission fuel. Actually, it left out a few things....but we can get to those in time. Just one example here. Collision properties are assumed smeared out statistically (mean free paths assuming random spatial distribution of the individual nuclei -- and they're not random as their charge tries to space them out more evenly), but in a focus situation they're not, as the density isn't "thermal" and spread out for say, the case of firing one single nucleus at another with accurate charged particle optics. At that point, the probably of collision can be raised with the only limit being the precision of your "aim" and timing, and can go to near 100%. The assumption that probability is purely density in a random distribution of "aims" isn't questioned in these writings either.
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Re: Why IEC fusors can't work

Postby chrismb » Tue Jan 25, 2011 2:45 pm

I'll say straight off that I have read this, his thesis, some of his papers and the few of his presentations around the internet also, and I am essentially in complete agreement with Rider. Sure, some of the analyses he runs through miss out some chunks of what one might call 'real world', but where else would you start?

Just to note, his main 'target' was, as I understood it, the 'Polywell' and the figures 1-1 and 1-2 are, I believe, 'prior art' images straight from the Bussard patent.

The reason I am fully on board with Rider is that a) he has followed precisely the same path of thinking I have done (co-incidentally, of course!), b) he has arrived at the same conclusions [by mathematics far more involved than mine; whereas I do the 'Rutherford-thing' of insisting an equation has to means something with real numbers in it, he is good enough to play tunes on the algebra], and c) he does not exclude the possibility that 'generally cold-locally hot' could be made to work and is humble enough to admit that, but simply that he's not figured out how to 'do it'.

It is my opinion that the key to all that Rider says is to recognise that this, his critique, grew from studying the Polywell in particular, and that if you read Appendix E in his PhD thesis, the 18MB one, it will become clear that Rider has also been properly, and rigorously, thinking through the same possible solutions that we are doing.

There is no-one that I have read that I think has as thorough an understanding of these systems as Rider, all the more so that he can actually see what needs to be done to fix the 'catch-you-out's, even if he's not got to the how-to. It is a loss to fusion research that he appears to have become sufficiently disillusioned by his own work that he changed discipline to bio-sciences!
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Re: Why IEC fusors can't work

Postby Doug Coulter » Tue Jan 25, 2011 3:40 pm

Right, well we agree, though his take on a detailed read is that debunking the Bussard design automatically debunks the surely-worse gridded fusor.
Because somehow ions don't hit the magnets in a bussard design like they do a grid. Hah, what baloney. And of course what I'm finding with grids is that you can design things so they take very few hits due to focus effects. I can run in 600-700w of power on an accurate one without getting it incandescent now. So an awful lot of the input energy isn't going there. Most of the heat appears to be generated at the tank walls from electron strikes there, as well as the X rays from there. I'm working on some one pixel cameras for gamma and neutrons to prove this beyond doubt.

I will have a lot more to say as I go over all this again. My main issues are some of the assumptions and combinations of assumptions he makes to get to math even as tractable as it winds up (not very, in other words). Because in some of the cases, if even one of them is even a little bit wrong, the thing just falls completely apart again. He fails to cover some (all?) situations that don't involve equal numbers of ions and electrons for example, and this isn't what I measure in the lab at all, not even close. This leads to the line that made me kind of unpopular over at fusor.net, where people would assume ions when they wanted to tug on them with some field, then silently assume neutrality when they didn't want to have them repel one another. Unless you have a specific mechanism to accomplish that, you just can't have it both ways at once! So while pretending to cover non thermal cases, he lets assumptions of thermalization creep back in to the predictions here and there. Yes, as is obvious, things will thermalize unless you take steps (as both our approaches do) to deal with that. They don't start out that way, however, and with feedforward math, especially stuff on the point of becoming divergent, you've got to get the initial conditions right!

So, he doesn't handle the case of time varying fields, which both of our approaches use. He doesn't touch the case of pure positive charges (like in an ion trap) which my approach uses. No bunching, and as far as I can see -- no explanation for the little recirculation that does exist (there's some kind of circulation there, just not as much as most fusor people wish for, and it may not be recirculation, but just new ion production in places that cause the new ones to go through the grid again).

Or in other words, his sins are in making assumptions that maybe aren't quite right -- and republishing "prior art" ones that are wrong and not mentioning they are wrong counts there, as well as plenty of sins of omission, though I will look at that appendix again myself -- going through the long version now.

One thing I caught somewhere in there was an assumption that this calculation sets a lower limit on losses via electron/ion transfer in maxwellian distributions which both fails to take into account he possibility of non-maxwellian ones, and also makes the barely stated assumption that any kind of deviation from pure-thermal makes it worse. This one has been proved wrong by of all people, the tokomak boys, who are finding some of the previous instability modes get better at really high powers, after which they help reduce losses, not increase them. Maybe subtle but that incorrect assumption breaks the following two pages of math right off. Of a case where you're working in a more ion-trap-like configuration and there are essentially no electrons present to create these various losses at all. Uh oh, broken assumptions again.

Early tests of the composite grid seem to say I can shove in a lot more power with less gas pressure, and less light losses, as well as less heat everywhere but the tank walls. I took that one out as there were other issues (long break in time seems to be a big one for that design, and sputtered graphite getting on the ceramic) as I have some demos for beginners scheduled Thursday and Friday, so I went back to my base configuration for that. That will do fine (better, really) to teach them the things I need to get into their heads to save them some time getting going.

The big lesson of a lot of experiments here is that this "simple" system is more than capable of some interesting kinds of emergent behavior (which make plenty of sense with the laws of physics, but only after -- in hindsight), it's a lot trickier than mere hydrodynamics, which itself has very little useful feed-forward math -- it can predict the onset of turbulence for example without saying what kind of which direction it begins in and where it winds up. Just that above some Reynolds number you get turbulence. That kind of thing is useful, but not sufficient in cases we're trying to deal with here.

This tells me more lab time and less computer time is what's going to be needed (which the tokomak guys also found out recently). The models simply aren't good enough yet.
I think it's important for people to gain an empirical understanding, that all important "feel" for things to help progress -- example, how much current of particles of what energy can I push down this pipe without losing a certain degree of focus? What's the actual force (in grams, tons, dynes, whatever) between two D's at the point of fusion, and how does that function vary with geometry in a many particle situation? Or in other words, what the effective "spring rate" and time constant given the masses we have -- and this non linear spring we also have? What is the velocity and position vs time plot of a single ion in a fusor in the fields generated by the grid and the other ions? Things like that.
These are all approachable with relatively simple experiments and math -- but I don't see anyone doing it other than my feeble attempts, which so far have been pretty feeble indeed, and I'm kind of asking for help on that here.

Yes, too bad he quit this line of work. I'm guessing some discussion with him would be profitable, he's one of the few with a clue. But even he falls into some of the more obvious traps.

Hey, if this were simple, someone would be doing it already!
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Re: Why IEC fusors can't work

Postby chrismb » Tue Jan 25, 2011 7:02 pm

Doug,

Rider has dealt with 'all ions' elsewhere. Not sure if it is embedded in his thesis, but you can see it in a presentation of his;

http://www.fusor.net/board/getfile.php? ... tt_id=3718

..see slide 14, which indicates a max of 100W/m^3 if you try to do fusion without electrons.

Of course, if 100W/m^3 is all the power/neutrons you are after, then he isn't saying it is not possible.....

So he tends to leave 'all-ions' alone because he discounts it as a route to fusion energy, which is his goal/discussion point.
Last edited by chrismb on Tue Jan 25, 2011 7:07 pm, edited 1 time in total.
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Re: Why IEC fusors can't work

Postby chrismb » Tue Jan 25, 2011 7:06 pm

Incidentally, did you see my recent reply on fusor.net to a similar question? I said much the same - enemy no. 1 as I see it is thermionic electrons running away and taking electrical energy with them (and the current driving that is what gets the grid hot). Your graphite grid is a cool fix! I'd still like to see you wrap a solenoid around the whole thing and generate a few 10's or 100 gauss. That should be enough to bog the electrons down, without upsetting the ions too much.
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Re: Why IEC fusors can't work

Postby Doug Coulter » Tue Jan 25, 2011 10:09 pm

I will check that out, I'm still going through the initial papers at this point. I'm still looking to develop the math I mentioned above -- where do the curves cross ideally in a case where we are looking at spacing vs probability of fusion of two nuclei, and how hard is the best hard to push them together (for how long) for the least input and most output. This math doesn't exist as one piece yet. Intuitively, the more ion current you have, the worse that gets for Q. After all, all the nuclei repel all others until they fuse so that's an N x N x N force kind of thing, and the shape of probability of fusion vs time and distance is it's own (squared?) shape. Until you have that simple(?) thing worked out, the entire rest of this might be moot.

None, or nearly none of the electrons can be thermionic in my system, nothing gets hot enough. They're all secondary emission created. Ions hit the grid (heating it some) but each one seems to knock out several secondaries (which only take a few eV energy apiece to do, and a certain multiple is observed in experiments going way back to the middle of the last century) which are then seeing the field from grid to tank as a quick way to the tank walls, where they hit and release another set of secondary emission electrons, nearly all of which have relatively low energies and see the same field taking them back to the tank walls. Just as in a triode tube, those latter batch don't matter much, as they return to the anode pretty quickly. It's the ones generated at the grid that make the problems, and the difference between graphite and tungsten work functions for electron release in this context (single digit eV) is nil, but yes, the graphite stays much cooler because it radiates heat better, and is more thermally conductive -- there is a conduction path in my system for heat via the fat copper feed-through stalk. Secondary electron emission is well studied as a result of vacuum valve development (and photo-tubes, but here we're working the opposite side of the street). Limiting the current of direct ion hits on the graphite with those ceramic rods does seem to help a bit, but they are arcing through as they gather field from ions hitting them on the outside side too -- I may have to redesign that to make them more vane like so they are wide enough to hold off the voltages.

If you went to multiple grids, there'd be other effects from secondaries, of course, that would have to be controlled -- see the development of the pentode, and later the beam tetrode for details on how that's been found and and taken care of (sometimes using the extra electrons to advantage as their own field can help direct new ones in the resulting net field). A fusor operating with a single species (just ions) is directly analogous to an inside out electron tube, with a virtual plate in many regards.

I'll have to see where the 100w per cube meter (of what? Total volume, inside the grid?) comes from, but for the moment as I break much above the micro-watt level I'm scaling back down -- that's my more or less arbitrary limit on how much neutron radiation (single digit millions/second) I want to have in my lab with me there too. I am not yet in the know enough about how things act to even determine that it would be better at higher or lower volume, but my intuition is that at lower ion currents a lot of things are going to be easier. Size probably matters, but maybe not "bigger is better", dunno at this point. I do seem to be getting the highest Q's here in other experiments where the ion current is pretty darn low, more in line with factor 60 less than what would work well with electrons the same energies. Everything starts acting more like simple theory at that point. Bunching may help a heck of a lot, also don't know, but intuitively it's a lot easier to catch and shape a big loose bunch at some larger radius before firing it at center for a very short time (and short focal length, the idea being to minimize the area under the time/space volume they are close to one another) -- the initial big space implies less force needed to contain a bunch of ions, and more time for them to get spread out equally spaced in the bunch (eg cool off in essence) so that when you fire them though the focus, you've got real repeatable and tunable conditions each major pass. By defining trajectories and accelerating the bunch(es) while all the components of the bunch are still far apart, you get them all heading where you want (including possible pre-corrections) easier, and once they're moving fast, they simply pass through the focus before much spreading can occur -- this is also well worked out in basic CRT design. They get a similar effect in big linacs, where there the effect is time compression due to relativity effects -- the particles get heavier, and this is good because E/H field focus fields are no longer strong enough to keep focus when they are a tiny fraction of the already-achieved energy down the axis.

As I progress along these lines, generally what I'm seeing is less light and heat to the point it gets hard to photograph, or even see in the dark, but more output with the same or less input...so I'm following a gradient in the design space it seems. Whether it leads to a local or global ideal point is yet to be found out.

And just about everything I've tried that disturbs the "dynamic equilibrium" vastly increases net Q, even pretty stupid appearing things like injecting 60 hz on another electrode in the tank that switches the main grid off and on (the second electrode also acts like an electron sweep-out on one half cycle, and a nice ion source on the other). So I'm hot to try some real bunching at the frequencies that the math says should be the right ones for electromechanical resonance with the ion cloud. With the 60 hz thing, during the "normal" half cycle, I do see main grid pulses at about 1-2 ms intervals, and that's when all the neutron counters mostly count -- so something a bit odd is going on, as that time interval is far too long unless things are going back and forth a bit in some sort of supercycles per pulse. Transit times should be in the mhz region.

I have fooled with magnets a little, and last I tried, no effect I could see from a 4" diameter ~500g at the face magnet slipped over the FT just behind the grid. Might take more than that. This would be easy to try and it's on the list to get done -- I'd just have to build a support for two of them facing each other, insulated electrically, just past the ends of the grid, and accept that they're going to fail in a few minutes due to heating, and besides, mechanically intercept any ions moving through where they are that weren't affected before. But that should be enough test to learn whether it's worth pursuing. You must know that a field that makes the gyromagnetic radius less than that tank is much tinier than needed here due to some electrons being sped up, and all of them being jiggled by forces from the other particles (see Rider!)...I expect to see much difference it's going to take a couple thousand gauss, actually. But it is worth looking at.
If it really takes the big fields that the theory indicates (not the oversimplified version) than it's not going to be super practical unless it gives a huge gain. The outside of the chamber is already too hot for all but very specialized wire insulation (eg fiberglass or similar). Make it self heating by winding losses on top of that and I see real design issues there. I'm already seeing 200-300c type chamber wall temperatures when I push in the power.
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Re: Why IEC fusors can't work

Postby vmike » Wed Jan 26, 2011 11:17 am

I'm always hesitant to post, simply because I don't necessarily see things the same way as most people. After reading the papers the first thing that pops into my mind is, "can't work for what?" There are a wealth of successes listed in the papers posted. I've always thought of IEC fusors as "tools" to discover paths to new knowledge. It has been evident from my earliest experiments this was a tough road to break even or power generation. But it is full of anomalies and detours, obstacles and strange results, what a great tool for learning. Not to mention time and money sink. :)

As a side note, for a living my job is to make PHDs look good at any cost, because that is the product we sell. (Even though I are one.) The one thing I've come to learn after leaving the private sector to become institutionalized, a PHD can always tell you why something will not work, even if they've never tried it!

To me." it's all attitude and perspective."

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Re: Why IEC fusors can't work

Postby Doug Coulter » Wed Jan 26, 2011 11:47 am

vmike wrote:I'm always hesitant to post, simply because I don't necessarily see things the same way as most people.


Around here, that's probably the best reason there is for posting, actually. It's the whole point of having more than one of us! We (like everyone else) don't need a ton of disagreement for its own sake (especially if there's nothing to back it up), but reasoned discussion from varying points of view is how the very best stuff gets done, at least in my opinion and experience. A single point of view will always get "stuck" on something that is a little beyond the owner's vision, or at least it happens all too often, even to me, and I'm pretty wild and wide open intellectually.

I agree, this is a fertile field for learning -- we are working in an area no one else really is as I mentioned on another thread. This "simple" system produces all sorts of "emergent behavior" most of which is only obvious in hindsight, which to me is an indicator that there's probably some low hanging fruit, because most of it wasn't predicted by the "authorities". And therefore hasn't been exposed to the "many eyes" that "make all bugs shallow" yet. So here we are, trying to do just that.

I don't have anything against PhD's if they are also smart. What I object to is those (formally educated or not) who don't know what they don't know, and make from-paper predictions of what will happen in the lab without taking things like emergent behavior into account, using barely-understood (by them) theory to do it. Those guys need to get into a lab a little more before they spout off. They need to see more than a picture of a fusor as tuned for what the owner thinks is best operation -- they need to see all the modes these can get into or they have a very narrow preselected data set to work off that doesn't reflect all of reality too well.

When I see a paper on this (especially one as nice as Rider's) by the guy who finally also gives us a closed form version of the three body gravity problem -- then I'll be a lot more impressed.
That is what is lacking in all modern math theory so far -- too little predictive ability, just a way to explain things afterwards. Good as far as it goes, but when people who can't do prediction step beyond what they are good at, I'm instantly suspicious. Zero percent of them predicted the 500x better Q pulsed mode that trivially happens in my lab anytime I reproduce the conditions.
And guess what -- free particles responding to E fields imposed, and their own, are just the multibody gravitational problem, with a few little tricks on the side.


This guy seems OK, actually, he's giving it a good try, but as I said, had to make so many assumptions to make the math tractable that he missed a number of possibilities (or so it seems to me) which might well invalidate that math as it applies here -- because it may not apply with that further knowledge (from the lab) as stated. Or it might. His objections are mostly valid within his reference frame -- your standard DC driven fusor, but I suspect his frame - and even he doesn't seem to be able to hew to it consistently. I don't blame him for that -- it's hard to hold all that in one's head at once, and if you go in with some bias for what the answers will show, it becomes near impossible to discover things you didn't expect.

My feeling about all too much of modern science is that if someone brought a researcher a petri dish that had some weird fungus in it killing the desired culture, it would just be done over, more carefully, and the fungus that became penicillin would elude us to this day. I'm therefore trying really hard not to be like that! Really, I'm trying to expect the unexpected (which is pretty hard to do in real life) because looking back on the great advances that have been made -- it usually played a pretty decent role in the process. One has to be willing to see it and willing to change direction when one does, which we know isn't always easy. Usually it's all too easy to cling to a particular view and toss out any "outliers" in the data that might show up, instead of chasing them down to find out if that's what they really are. A group of outliers might actually be part of some other valid distribution!

At any rate, my wanting to post this and discuss it was just that -- I don't think even the writer proposes that his analysis covers all possible modes -- just the ones he assumes, and neither Chris or I are working on approaches covered by these papers on purpose - we think the guy has a clue, just not ALL the clues.
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Re: Why IEC fusors can't work

Postby chrismb » Wed Jan 26, 2011 6:45 pm

Actually, I think Rider almost totally nailed what I am doing right through the middle! I came up with the idea in ~1985, he wrote his thesis in 1995, and I started building a prototype in ~2007 - quite independently of each other. I've never seen anyone get even close to describing it, yet here is Rider giving a description of my device, point-by-point, without ever actually knowing how to create such a device! It's spooky for me to read, actually.

Go see p.270 of his PhD - section E2.2. It is so prescient of what I am up to that after reading that section I am now calling my device 'closed orbit, high velocity resonant' following his description, because I think that is a very concise/insightful description of it.

In particular, at the end of that section, Rider writes 'these types of devices might also be useful for other purposes' and, indeed [and to address Mike's post] I have filed the device as a patent, claiming general ion manipulation uses, for utilities including mass spectrometry and separation, and beam forming processes.

I think you should get down to reading the whole of that Appendix E, Doug. I think you'll like it!
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Re: Why IEC fusors can't work

Postby Doug Coulter » Wed Jan 26, 2011 8:13 pm

I will, Chris. Right now, I have visitors for demos starting tomorrow AM, so am getting ready for that and hoping nothing new fails in the interim..."I'll be back".
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