Laser-Stimulated Fusion In The Core?

[acaldarone]

(This is a rather large deviation from the common fusor, involving the elimination of the outer cage, but because it still incorporates the inner grid I think it still is related enough to standard fusor technology to pertain to this board).

Here's a quick schematic I did in Paint.NET about what I am theorizing. For simplicity, I left the vacuum/electrical/pumping equipment out and put in the bare basics of what I am proposing. It is a hybrid involving the fusor system and something similar to inertial confinement fusion. Instead of two cages with opposing charges, I propose using several (can vary in the final model, in this schematic I put two) ion guns which fire deuterium toward a central normal grid. However, in addition, I propose putting a third electrode in the center, with the same charge as the electron guns, but at a smaller value. Powerful enough to keep the ions from collecting on it and damaging it, but weak enough to keep them from repelling too far and limiting collisions. This would also be the focal point for one or several lasers, which would provide additional energy for the fusion reaction through heating. Obviously most of the force would still be coming from the electrical potential between the electrodes, but a small amount of laser energy could = more energetic ions = more collisions = more fusion reactions = more energy. Right now the fusor's main drawback is the probability of ions hitting each other in just the precise way of creating fusion. A lot of energy is put into the device to get all those ions moving, but only a fraction actually do what we want them to and fuse. Getting more to fuse can tip the energy return odds in our favor.

Thoughts? (This is from a layman who only studied Newtonian physics in high school and is for the most-part self-taught in nuclear physics, so be gentle. ).

EDIT: Just realized I had the signs flipped. Derp. Just mentally flip them when examining this schematic.

[John Futter]

Andrew
The biggest drawback I can see is getting a powerful enough laser with a spectrum that D will absorb

The other thing is that the D if it absorbed laser energy would become more energetic therefore moving away in some random manner

keep thinking

[acaldarone]

But wouldn't more energy = more sum collisions = more opportunities for successful collisions that could result in fusion? Or would the increased randomization cancel out any increased probability of fusion-capable collisions?

An alternative that could also be considered is pulse lasing. Shooting short, powerful bursts at the core. Either way, there needs to be, IMO, an increase in energy and collisions if there is ever to be breakeven. I am also, besides lasers, hypothesizing about possible uses for magnets to guide ions to have more fusion-capable collisions.

[Jerry Biehler]

I have an excimer laser that would probably do the trick. Nasty gas though, fluorine in that stuff. I think it lases at 184nm.

[Edward Miller]

Laser's only add more cost/inefficiency. By the time the light hits the target you only have ~2% of the energy you put into the laser. Also they are very very fragile and complicated. To get time a laser powerful enough to do fusion you'll have to wait years and get a lot of support.

The ions are already moving about at fusible energies, adding more expensive heat doesn't really help solve anything. If you wanted to add more RF or something would be faster/cheaper/easier.

There are cheaper lasers that I believe can be used for diagnostics of the plasma that would be interesting work...

[Richard Hull]

Lots of bright ideas, but as Edward notes,...... Lotsa' folks coming to the table with ideas before knowing key efficiency issues or crunching numbers at even the simplest level. Don't feel bad though, NIF is already doing this sort of thing.....Wasting energy in the quest of fusion.

Richard Hull

[acaldarone]

I take it you don't have much faith in ICF, then?

I wonder if one could incorporate aspects of MCF into the fusor? *grabs his schematics notebook and starts doodling concepts*

[Richard Hull]

I have little faith left to give after 60 years of observing nothing for countless billions spent on fusion. Finally, nothing sounds remotely feasible that is on the theory table or in progress of having money spent on it.

Fusion is pretty much a wash.

It is more like the Edison lament offered up by Tesla. "Edison will look for a needle in a haystack by removing one straw at a time"

Of course, Edison, after trying thousands of combinations did come up with a workable electric light, but he didn't spend tens and hundreds of millions on each iteration.

Richard Hull

[Chris Bradley]

Richard,

This is especially for you! - A video of a presentation on laser fusion. I just know you'll not be able to contain your enthusiam to watch it all and lap it up, every second.

http://science-education.pppl.gov/video ... H.264.html

[I can't actually say I've watched it myself.... I copied it from the url to a local drive, http://www.pppl.gov/video/SOS12FEB2011_ ... mputer.m4v , then fffast forwarded it]

[acaldarone]

Wow, never thought I'd here something like that in the fusor community.

Fusion, IMO, is simply a door we need to unlock. We've seen it through the peephole, now it's just a matter of figuring out the tumblers and tapping it's full potential. We've managed to crack so many of mother nature's codes, why not this one, as well?

We've already cracked half the code: we've managed to overcome the coulomb force to replicate the sun, now it's just a matter of increasing the efficiency. The fusor's main drawback is the inaccuracy of ion collisions, ICF is the need to power the laser, and MCF is the need to power electromagnets. To me, it seems like we will find the key to fusion somewhere in the middle of all of these.

If we can find someway to reduce the energy input into the machine to JUST ENOUGH per-ion for it to overcome the coulomb force, and then a way to capture that energy*, we can make this work. Science is always overcoming opposition (sometimes even within it's own ranks), I have hope fusion energy can, too.

*I have theorized that it is possible to use something like a chamber-lined photovolt that is sensitive to X-rays, gamma rays, and even neutrons themselves (and possibly decay products), to generate electricity.

[Carl Willis]

Energy generation is the most sensational application for fusion, but a goal that is particularly distant within the scope and resources of individual hobby fusion projects. A lot of newcomers measure their ambition against this lofty goal and even arrive with the thought stuck in their heads that they'll be the "lucky donkey" who solves the global energy crisis. However, my observation over the last 12 years of forum participation is that the treatment of this particular application has been limited to little more than a noisy and endless parade of dime-a-dozen ideas (most with obvious shortfalls, most repeating earlier ones, most betraying a lack of close study of the particular salient issues).

Our most realistic role in fusion power, as a community of hobbyists, is to cultivate experience with relevant experimental techniques and confer a first-hand taste of SOME of the field's challenges. People can take this kind of education into professional careers where it will serve them well and where I think they have a much greater chance of making an impact. The fusion energy problem is so multidisciplinary that I see large professional projects as far and away the most likely avenue toward a solution, wishful thinking of certain individuals notwithstanding.

-Carl

[acaldarone]

Which is where I hope to take it (I'm hoping I can use the fusor as a basis for a doctoral thesis eventually).

Anyway, I just don't agree with fatalistic attitude I'm getting. The whole "always 40 years away" thing has one major flaw, and that's the exponential advancements of technology. Other things humans once said would "always be 40 years away" actually came to fruition. Eventually fusion's numbers will come up as well, and I personally feel that emerging nano and quantum technologies will play a role. For example, better ion channeling systems or ways to capture fusion energy.

It's time BETTER come, fusion is our last, best hope for deep space travel. If we ever hope to send people to the stars, we need fusion.

[Dan Tibbets]

Laser assisting fusor performance?. I would think no on first glance. Fusion IC is far different from a fusor. Inertion and compressional heating and ignition is involved with laser fusion. Fusors are electrostatic devices. They use voltage to heat the plasma, and if there is any central convergence, some compression effect. But this is to densities of perhaps 10^15 to 10^22 particles per cubic meter. Laser confinement fusion compresses the fuel to perhaps 10^27 or more particle densities. Atmospheric density is 10^25 particles per cubic meter.

Heating the particles to desired fusion temperatures is a trivial matter in a fusor. The areas where improvements might be made is in the effective densities, beam- beam chariteristics, convergence (central focus (density related again)). On the other side of the equation is trying to minimize input energy- improve containment.

Lasers are good at exciting atoms at resonant frequencies- the electrons climb to a higher orbit or escape (ionizing). But exciting/ heating nuclei is a different matter. Much higher energy lasers may be required, Energies of over ~ 1 MeV may be required, ie:x-ray lasers, in order to excite the nuclei to the extent that they start falling apart- of course these tend to be endothermic reactions Microwaves can assist in ionizing and perhaps heating the electrons(?) which can also result in ion heating (?). And changes in the distribution of ions may occur. Things like POPS efforts. Perhaps a Maser might be better than a laser(?).

Dan Tibbets

[Chris Bradley]

Andrew Caldarone wrote:
> Anyway, I just don't agree with fatalistic attitude I'm getting. The whole "always 40 years away" thing has one major flaw, and that's the exponential advancements of technology. Other things humans once said would "always be 40 years away" actually came to fruition.

It's not a 'bad' sentiment to harbour, but it is *just* a sentiment unless you do something about it. You can't wait around expecting someone else to magic something up, just because that's how science seems to have happened in the past. Someone's got to *do* something about it.

Looking to the skies with your feet on the ground is quite different to head-in-the-clouds. The objections presented reflect a concern that you are in the latter scenario. Drum up your figures for ponderomotive forces, confinement times versus laser pulse times, plasma densities and all the other assorted variables that might feed into your dream reaction and let's see what the likely boundary conditions are. Are the size/scale/density/power/material capabilities even remotely plausible?

[Richard Hull]

Chris,

I watched the video. Those who have been at my HEAS conferences over the years have met my lady friend Kim Goins. She is a research physicist at NRL. She has worked on the KrF laser as part of the NIKE laser group which has now morphed into this ICF group. Kim was small in stature and was the physicist of choice to change the Hibachi in her early days there. She notes that the noise of the firing of the NIKE laser makes it to every office in the facility.

Kim gave me a great Litchtenberg figure in a large piece of the lexan from one of the hibachi firings replacement efforts.

Kim has now moved over to another ultra-secret portion of the lab that is not involved with fusion at all.

As with all such efforts, and as the man said, Fusion is the energy of the future and always will be.

The robust 24-7 operation of a GW fusion power plant built around this ICF concept is the game stopper. If one is sympathetic to the speaker's quest, he has noted that all that remains is seemingly a mechanical and engineering issue.

Still, no pellet has been dropped in the KrF system. He is relying on the NIF testing as proof of concept at some core level. A big issue is the cost of any final, power ready system in competition with that of a fission plant.

As noted before, I do not believe anyone who is reading this or even those just born, will ever, in their lifetime, use one watt of fusion energy delivered from their wall outlet.

Richard Hull

[acaldarone]

I wasn't talking about my theories, just fusion in general.

And if my theories do seem a bit dreamy, it's because in their most earliest forms...they sorta are. :/ I've said my reasoning for this several times, already. ATM theorizing is all I can really do, I'm transitioning from a gap year after high school into college this fall. All my time and money is going to that in the short-to-middle-term. Had I found out about fusors sooner (when I had the near-term time and funds to build one), I'd probably be building something more tried-and-true, and modifying it to test different theories after the fact, but since all I can do at the moment is put pen-to-paper, I might as well be working on some rough theories while planning a basic fusor (which I HAVE been doing, too ). That way, once I'm taking my physics classes, and I can begin putting numbers to the mechanics, I can begin to refine my theories, and have one that I can use for an eventual doctoral thesis (my ultimate goal).

[Edward Miller]

I don't think anyone intends to be pessimistic.

Very smart people have spent tens of billions of dollars and decades of research trying to crack this code and have not succeeded. Of course we're all a bit smarter about plasma's and ions but nowhere near solving the fusion efficiency problem. The Sun is very inefficient and of course that works out well for our planet but it's technique doesn't carry over very well to our machines.

It's not that simple either. The solution is not in the middle. Ions and electrons are the problem. You can't live with them and you can't overcome repulsion without their energies. We've done some amazing science over the past 150 years but we're not that smart, we have a God complex. The reality is most energy is made by burning stuff to boil water. Computing advances rapidly but it's reward is directly tied to it's incremental progress. Fusion is stuck in the punchcard era. Breaking stored energy is much easier than combining atoms efficiently.

Check out Rider's paper on better routes to fusion: http://www.longwood.edu/assets/chemphys/FusionRoute.pdf

It starts out simple. Just make and keep ions in a small space. As you dig deeper you start to discover new problems. The electrons get away and cool everything off, so I'll fix that with x. But then the plasma is unstable... There are layers upon layers of problems with fusion. The more you know, the more you realize you don't know. And then you stumble on something truly original and start working toward testing it. And after you put your own blood, sweat, tears, and money into testing your original idea and you find another layer of problems and curse the whole damn thing.

And let me add that any new technique for fusion will get opposition from the scientific community. Scientists demand calculations, data, numbers, and experiments. So if it's new you'll have to test it yourself. They'll instantly write you off as a crackpot doing cold fusion. Most people don't even believe that it's possible to do fusion on a table top via a fusor.

You can't just throw magnets, or energy, or money, or brainpower at the fusion problem and expect any return other than your own personal intellectual enrichment and another layer of issues. There are still a lot of unknowns in physics as you get deeper into it. I've talked to some of the smartest living physicists about some of these problems and they say the same thing as most folks here, "I don't know, do some experiments, and we'll see if we can figure it out."

So maybe the problem is outside of our mental capability and a computer given sufficient information about plasmas and particles could figure out more efficient designs/variations. I know of two legit groups that are testing computer designed plasma systems. They're probably getting into new territory/layers but I doubt plasma will ever work for reasons outlined in Rider's paper.

Why we don't even know how to make powdered detergent and the God complex.
http://www.ted.com/talks/tim_harford.html

If you're interested in the latest MCF check out GeneralFusion.

It would be easier to work on a device to convert energy from fission "waste" material.

We don't need to send people to the stars. The little robots like the ones on Mars work very hard and collect a lot of data and don't complain.

Options
1. Try to improve plasma systems but add magnets/lasers/rf/xrays and/or change the shape to sphere/cylinder/toroid/etc.
2. Trial and error of new ideas. Fail cheaply & rapidly. Repeat.
3. Let computers iterate novel experimental designs.

I think this is the best hobby ever and I enjoy learning about all of it and interacting/collaborating with fellow fusioneers and scientists. Having experimented on my own design, I'm personally working on getting a degree in physics and pursuing the problem via new ideas and computing.

[acaldarone]

Thanks for the links. I love TED talks. And some of those fusion routing methods look quite interesting. So many possibilities out there. Maybe it's just that I'm a usually optimistic person, but I view the fusion problem like an artichoke. Yeah, there's lots of layers to uncover, but as we uncover them, we learn a bit more (and all tested methods of fusion so far have added something to the knowledge pot), and eventually we get better at navigating the layers, and someday we'll reach the heart.

Oh, and we will eventually need to send people to the stars, when our star goes red giant and Earth ends up being a crispy critter consumed by a giant red fireball. Fusion is the only feasible option (there's antimatter-matter annihilation, I guess, but that opens up it's own set of problems not to be discussed here), both fission and chemical reactions can't do it.

And I like all three of those options (but aren't 1 and 2 basically the same thing? ). Lord knows I have tons of ideas I'd love to test someday. (What I've posted on these forums is only a fraction of what I've been designing).

[Richard Hull]

Ed Miller has a very balanced approach to the fusion issue, but more importantly, he sees right to the core issues that I have hammered away on for years here.

We still, and will probably continue to, boil water for all our energy needs in the gigawatt range. (Put on the kettle) No super efficient direct conversion of fusion energy.

We will surely continue, for a long time, to "hunter-gather" stuff with locked up potential energy for our massive energy needs. No creation of net usable, distributable energy from fusion. (unless you have a giga-watt solar panel)

But, hey, isn't 100% of even the hunter-gatherer stuff attributable, over the eons, to fusion energy? The issue is, we get it back as unit electron volt energies, for the most part, while lusting after the mev energies that we just can't have from direct fusion.

Dreams? Hope? You bet! These are always allowed and welcomed in order to escape, if but for a little while, the realities of life and the greasy, hands-on part of living it.

Richard Hull