Aneutronic fusion questions...

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Spencer DePue
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Aneutronic fusion questions...

Post by Spencer DePue » Fri Oct 08, 2010 9:40 pm

Hello everyone, I am designing a hybrid pyroelectric/electronic polywell and I want to know somethings about the detection of aneutronic fusion in the polywell. First question is how would I know besides physically seeing a plasma, that I am getting aneutronic fusion with proton/boron fuel sources. (Detection equipment ideas would be useful) My other question is that if I achieve fusion and find a way to harness it, would the energy generated completely melt all of my electrodes and the excess wires? Please advise.

Dan Tibbets
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Re: Aneutronic fusion questions...

Post by Dan Tibbets » Fri Oct 08, 2010 10:11 pm

What ever you use to power the system (accelerate the electrons), you will needs millions af watts. And to power the copper magnets (or to charge up the superconducting magnets), you will need perhaps more than a million watts. If you are going to create a plasma that can fuse P-B11 at required levels, you will be producing enough waste X- rays to kill your self within minutes (unless very well shielded or far away). There are occasional neutrons produced and at the levels for break even, these would probably be easily detectable, or even very dangerous, though you would have to be careful to be sure they were from P-B11 side reactions instead of contaminating deuterium . The vast majority of fusion products are Alpha particles. These are easy to detect, but the detector would have to be inside the vacuum vessel and would be exposed to lots of electronic noise, thermal loads, etc. Perhaps some type of plastic detector would work (like Cr39).
And, yes, your system would melt into a puddle of metal unless you aggressively cooled the system. The projected cost for a breakeven Polywell is ~ 200 million dollars. This probably includes little or no cooling (except for the magnets- a challenge in itself), as it will probably only run at a few seconds at a time.

Piezoelectric power might deliver high voltage, and perhaps can be scaled up massively to provide the necessary current, but this is a pulsating source, unless you hook up a bunch in parallel with capacitors. And remember, you have to load the piezoelectric power source first by stressing the crystals. This take more power than you get out of the crystals, otherwise you are violating the second law of thermodynamics. Else, why worry about fusion, just use the crystals as your power source.

If you want to only demonstrate a little P-B11 fusion in a Polywell like device, the challenges are tremendously less, but still probably requires a lot of work and probably 10-100,000s of of dollars.

The current EMC2 experiments may be extended to try to demonstrate P-B11 fusion (not breakeven). This is with a 60 cm (?) diameter magnet grid, will require completely different fuel input, and to get to this point, they will have spent $5- 10 million. The electron accelerating power source is one of the simplest requirements to achieve.

If you want to use piezoelectricity , I suspect it might more suited to a Dense Plasma Focus type device, where you want very short high voltage and current power pulses.

Dan Tibbets

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Carl Willis
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Re: Aneutronic fusion questions...

Post by Carl Willis » Fri Oct 08, 2010 10:39 pm

Spencer:

Applicability of various detection techniques depends on what the goal of the measurement is (qualitative, quantitative, degree of precision) and how intense the reaction is (or is intended to be). As the designer of whatever you have in mind, you would need to clarify those points to get meaningful suggestions.

But first things first. Your second question about harnessing fusion and melting your electrodes from the energy generated makes me wonder how much background research you have done and whether any of the project you are designing has a grounding in physical reality at this point. Our forum has historically gotten very many pronouncements and questions linked to p-B11 fusion, suggesting very limited familiarity with fusion concepts and research in general on behalf of the contributors. The fact of the matter is that NO amateur effort has yet even seriously contemplated p-B11, and few fusion professional fusion research efforts attempt it, for reasons that become obvious when one considers the hazardous chemicals, small nuclear cross-section, and other details of practical relevance.

I should add that the presence of a visible plasma is not an indication of a fusion reaction.

Also, detection issues should be posted to the Neutron and Radiation Detection forum in the future.

-Carl
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Spencer DePue
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Re: Aneutronic fusion questions...

Post by Spencer DePue » Sat Oct 09, 2010 1:51 am

Thank you for your input. I know a lot about fusion for someone who is an amateur. However, this is my first fusion attempt. I have been designing this reactor in theory for 3 years now and I am currently 17 years of age. I still need to prove that this reactor will work. The entire design costs under $3000. The majority of the cost is from the pyroelectric crystal, vacuum parts, and custom made steel chamber. According to some basic electronic theory, the wattage could potentially be in the millions range. ( 100000 volts x 60 amps- 6 million watts theoretically). All I need is a lot of lead, highly resistive output wire, and cooling. The reactor will be running for approx. 2 minutes. As much as I make this sound simple, I completely understand the complexity of this achievement.

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Carl Willis
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Re: Aneutronic fusion questions...

Post by Carl Willis » Sat Oct 09, 2010 4:02 am

So you have a lofty and ambitious goal--a polywell device driven by a pyroelectric crystal doing p-B11 fusion. Now this is not precluded by any laws of physics, but it's a multidisciplinary project of huge proportions, novel territory on many fronts. If you're serious, wouldn't it make sense to at least organize your project in terms of realistic, sequentially-approachable sub-goals?

For example:

-----------------------------------------------------------

>1. Design a small proof-of-concept "demo" device to make voltage, current measurements on pyroelectric crystals, test your magrid cathode ideas, get a vacuum system in order, learn fabrication techniques
>2. Build a low-power prototype to achieve easily-measurable, non-toxic, high-yield DD fusion, and solve any problems identified
>3. Build a higher-power prototype with further improvements
>[etc.]
>27. Experiment with the p-B11 reaction
>[etc.]
>118. Build a 6-MW power plant
----------------------------------------------------------

Right now, you're talking about detectors for p-B11, you're talking about 6 MW, you're talking about radiation shielding...and like virtually every single p-B11 enthusiast to grace this site before you, there is not a hair of practicality to the approach in evidence. If you'd made it to Step 26 (in my example), then it might make sense to talk about detectors for this reaction. And if you'd made it to Step 117, then it's time to be concerned about millions of watts melting your electrodes.

You're not even to Step 1. Traditionally, even for those of us with less ambition, getting beyond Step 3 is years (and thousands of dollars) in the coming. What do you say? Nobody around here is going to think any less of you or your goals for being a pragmatist and starting at the beginning...in fact, quite the opposite. Save the meltdown talk and the detector issue until their time. Instead, how about describing your work so far in more detail? What does your research plan look like?

-Carl
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Spencer DePue
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Re: Aneutronic fusion questions...

Post by Spencer DePue » Sat Oct 09, 2010 5:17 am

Yeah, I guess I am getting a bit ahead of myself.. I do plan to measure crystal voltage/battery amperage in the circuit as a "dry" test with no fusion or vacuum just to see what my real amperage/volts will be. I am somewhat cautious about posting my exact plans because of potential idea theft.. but I hope that those on this website will be trustworthy enough. But I really appreciate the plans, ideas, and general feedback that I am getting here. But even if the potential of my fusion fails at first, I can always work on it until I perfect it.

Starfire
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Re: Aneutronic fusion questions...

Post by Starfire » Sat Oct 09, 2010 9:39 pm

Search the forums - it has been discused before

viewtopic.php?f=13&t=5601&hilit=b11#p34045

Richard Hester
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Re: Aneutronic fusion questions...

Post by Richard Hester » Sun Oct 10, 2010 12:54 am

I would use a simple fusor at high voltage/lowish currents with a hydrogen fill to see if I could observe the p-B11 reaction at all - that would be a very ambitious first step. R. Hull's comments in the referenced thread on using a drift tube to separate out alphas for detection are well taken - that's something I've also considered.

Introducing the boron in a form that won't kill you, blow up the place, or corrode the insides of your fusor is a big, big problem. The boron hydrides are out for casual experimenters. Check their characteristics if you don't believe me. Boron halides are out due to corrosion/contamination/toxicity issues. What left is an evaporation setup using brute force current or a laser. Evaporation of boron is difficult with a normal setup, as it tends to eat up a lot of the boat materials used. Folks experienced in vacuum evap techniques are invited to chime in, as I'm sure it's done somehow. Ablation with a pulsed laser is the least problematic method I can see, requiring a good window with AR coating. The laser need not be all that ambitious, and one can use the number of hits/second to dole out the necessary boron concentration.

Since the inside of the fusor will eventually get coated with boron, shields and sacrificial windows will be necessary to protect the viewports and feed through insulator.
At any rate, there's enough problems involved to keep a well-heeled amateur busy for a few years. It would be quite a coup just to be able to observe the p-B11 reaction in a fusor, and worth a journal paper somewhere.

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Richard Hull
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Re: Aneutronic fusion questions...

Post by Richard Hull » Mon Oct 11, 2010 4:51 pm

Wow! This has already gone pretty far afield. A lot of good info has been passed on here. Carl has stated some proper steps in a tongue-in-cheek outline of some of those steps.

The aneutronic fusion of P-B11 is a buzz word that has never been turned into a realized effort by any amateur on the planet. Why a 17 year old is tilting at this windmill when he ought to just do the seocnd most simple fusion in the universe, (D-D fusion), to get some quality time with real, realizable fusion is a mystery to me. In the process he might gain knowledge of just how hard his planned effort is with P-B11.

Rather than be a total looser with a failed P-B11 effort and only say "I failed to do any fusion", he could say I did real D-D fusion and know what real fusion was like and still tried P-B11 fusion and failed due to its inherent cost and difficulties.

To say you are going to do P-B11 in a polywell system which no amateur has ever attempted and succeeded at with simple D-D fusion is a real cast of the net that boggles the mind.

Of course, when one is 17, one feels like anything is possible..........Until one gets tangled up with all the money issues, dangers, technologies involved and securing a vast armada of stuff needed to make those pipe dreams a reality.

Finally, No one here has ever done P-B11 and any suggestions given here are shots into a wilderness that no one has ever roamed in. However, those who do offer advice on P-B11 have done real fusion with there own hands and know that P-B11 is a dark world that demands more than they can muster in dollars and time. These are people with lofty degrees in physics and engineering with regular day jobs who can finance, out of pocket, their fusion efforts here. Yet, these same folks quake in their booties at doing P-B11, not because it is impossible due to the physics, but due to their wallet and the foreknowledge of just what might be involved.

No one here is even willing to make a polywell! This is partly due to costs and partly because they haven't seen any hard evidence of any polywell ever doing any kind of fusion.

You have a costly battle of the highest order ahead of you.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

Richard Hester
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Re: Aneutronic fusion questions...

Post by Richard Hester » Mon Oct 11, 2010 6:12 pm

I wouldn't say I'm quaking in my boots, but trying p-B11 before even getting D-D fusion is a road to frustration and failure. There are enough roadblocks in the way for the relatively easy D-D fusion to make that a big challenge. Best to try that first and get the obvious problems out of the way before tacking something hideously difficult. The D-D platform can also be used for perfecting the detection scheme needed for the alphas from the p-B11 reaction by using the protons from the D-D reaction. No one from this forum has tried this as far as I know, though some of us have the necessary detectors. The group at U. Wisconsin have detected D-D protons in the course of their experiments with D-He3 (the D-D is a side reaction to the main course of D-He3), so we know it can be done.

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