Alternative Reactor Design

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Royce Jones
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Alternative Reactor Design

Post by Royce Jones » Fri Aug 28, 2015 2:27 pm

I am looking at a change in the basic architecture of the Fusor as the starting point for future development, possibly leading to a Fusion/Fission reactor. I have rearranged the Fusor in an attempt to make it more effective. I call this the Linear Focused Fusion Reactor.

The Linear Focused Fusion Reactor is a form of “Fusor” but with a substantially different architecture. The architecture is cylindrical rather than spherical (there are some cylindrical Fusors), linear and focused from just two directions (compared to 360 degrees). The goal of this effort is to build a Linear Focused Fusion Reactor that can generate high neutron levels for use in a Fusion/Fission Engine for space energy and propulsion. The device is relatively simple and inexpensive to construct and based on well understood physics.

Benefits of the new architecture:
Compact cylindrical shape.
The fuel is completely ionized before it enters the reactor from each end. Current designs most often ionize the fuel slowly after it enters the reactor resulting in a very low level of active ions (>1%).
The reactor has a mechanism for confinement of low energy ions, at each end, which keeps them from flooding the reactor thereby reducing low energy (unproductive) collisions.
The center cathode grid is two-dimensional (rather than spherical), there are only two ways to approach the grid and each way is 180 degrees opposite resulting in high speed ion collisions. This is a major change in architecture and a patentable design.
The reactor operates at the “sweet spot” of D-T fusion at 100,000 volts on the center grid. However, this is achieved with only 50,000 volts since the well is two sided. Ions approaching the grid from either side are capable of fusion at or near the grid.
Another unique feature is that the ions that don’t fuse are collected at the end grids until they have sufficient energy to escape toward the center grid for another attempt. This keeps ions from randomly flowing around the reactor causing low energy collisions.
Permanent magnets are used to help confine the ions into a narrow band toward the center of the well.
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Linear.png

KevinCobley
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Re: Alternative Reactor Design

Post by KevinCobley » Mon Oct 19, 2015 1:27 pm

How do you propose to overcome the Brillouin Limit? This will mean that you have only a very low density of charged particles contained by the magnetic field.

Also the decelerating ions that don't interact will produce Brehmstrallung radiation as they decelerate in the field - this lost energy would have to be captured and recycled if you want to make net fusion energy.

Finally, Coulomb scattering will require that energy be spent re-focussing the beams after collision. The scattering is likely to be uniform in all directions leading to a general spreading of the beam, so the H field will do work to refocus them (assuming they dont impact a conducting surface on the way)

I thought about a similar scheme, but it seems not to solve many of the main problems of the Fusor and introduces some new problems by its linear nature.

Kevin
Last edited by KevinCobley on Mon Oct 19, 2015 5:27 pm, edited 1 time in total.
Don't ask me - I know very little.

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Richard Hull
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Re: Alternative Reactor Design

Post by Richard Hull » Mon Oct 19, 2015 4:10 pm

I am sure this design with minor modifications will fuse. Now, who will build it? Certainly not the proposer.... as usual. Will it fuse better than a regular simple fusor? ......Again, who is going to build it to prove it will?
Will it cost more than a regular simple fusor? Absolutely
Who has the extra cash, verve and know-how to make the ion guns, magnetic cusps, etc.?

It is really a straight-forward design as it is exactly what the original Farnsworth team did in 1964, but with a spherical chamber and 6 and then 8 centrally focused ion guns. Cost? About $250,000 in 1964 money.

Another brilliant armchair idea bites the dust.

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.

KevinCobley
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Re: Alternative Reactor Design

Post by KevinCobley » Tue Oct 20, 2015 7:24 am

Go easy on the poor guy - at least he's having a think about it. We all have to start in our heads to begin with - thats what makes Humans unique - our capacity for imagination.

I guess I'm interested to know whether the folks here agree with Todd Rider's analysis which basically claims all fusion reactors are impossible to make break even, or whether we think there is a chink of hope?

No doubt I should go search the archives..

Kevin.
Don't ask me - I know very little.

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Jason C Wells
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Re: Alternative Reactor Design

Post by Jason C Wells » Tue Oct 20, 2015 10:58 pm

I never shared my early designs with anyone. I was inspired by the polywell. My first concept was to make the polywell more spherical by making a dodecahedron apparatus. I wanted to squash those leaky cusps Bussard complained about. The polywell was expensive though. I was half way into linear acceleration before I made my first post here.

I wonder what I would think if I went back and looked at those designs now, knowing what I know. Maybe I should burn them before anybody finds out. There are a lot of ways to do this hobby badly. This community is tough, and tough it should be. I appreciate that about you guys.

Regards,
Jason C. Wells

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Richard Hull
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Re: Alternative Reactor Design

Post by Richard Hull » Wed Oct 21, 2015 4:32 am

Thanks for the comments about our being tough. I have been accused of negativity. Actually I am a set of gravity boots to wild ideas that fly in the face of common, easily acquired, basic knowledge.

Your comment about "the doing" was a revelation you experienced due to that "doing" you did. The "doing always shines a blinding light on the realities involved with fusion or any true effort that involves real hands-on, time and treasure. Ideas flood the active, thoughtful brain.... Most all have flaws. Only those that are shared can be critcally reviewed by one's peers. Peers who have been there, spent their time lashed to the mast, learned from their hands-on experience, personal time spent in the effort and personal treasure never to be returned, to "do" and actually did!

Negative returns on an idea by those in the know who offer reasoned responses from hard won experience is not to be laughed at or totally ignored, lest you proceed at your own risk. However if one's idea is so great and burning within, we can only say, "show me". Now the ball is firmly back in the poser's court and senselessly bouncing. Most posers of ideas just let that ball go through the naturally occuring decay of the bounce and allow it to roll aimlessly over to the sidelines. This is because they only have ideas and do not pack the gear to do.

Ideas that are based on real science with real physics behind them are the ones we respond to seriously. Wild machinations where physics is not even good enough to be considered dead wrong, but are more of a word salad of terms strung together with no real connection to reality are the ones that get either no response or terse rebuffs.

We and I am tough as we need to keep this site's goal of amateur fusion and all of the many facets involved in the "doing" focused, active and free of detritus

Thanks again for sharing you real world experiences with us related to your project. This is what the site is all about.

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.

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Steven Sesselmann
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Re: Alternative Reactor Design

Post by Steven Sesselmann » Wed Oct 21, 2015 7:31 am

Royce,

Your design is not completely novel. I have been building linear colliders for 10 years, just search the forum for STAR and FICS, both produced neutrons.

With the right parameters the ions can be made to recirculate through the cathode, so you don't need an ion source at both ends.

I am now working on FICS-IV but it will take some time to finish. I will post more on it later.

Steven
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http://www.gammaspectacular.com - Gamma Spectrometry Systems
https://www.researchgate.net/profile/Steven_Sesselmann - Various papers and patents on RG

Dan Tibbets
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Re: Alternative Reactor Design

Post by Dan Tibbets » Wed Oct 21, 2015 10:41 pm

Some observations that may be pertinent. The sweat spot for D-T fusion is closer to 50 KV or even 35 KV once some thermalization issues are considered. D-D would be closer to 100KV.
Lateral confinement by magnetic fields is a leaky process. With cusps and ExB cross field diffusion, loses can mount up. Edge instabilities may also contribute. Consideration of recirculation of the plasma through the cusps may be a critical component of such designs (re the Lockheed approach and the Polywel).

With a fusion/ fission approach many of the considerations are eased considerably. The fission provides the power, the fusion is just a neutron source to drive a subcritical fissionable fuel to the desired output. This is a different control mechanism than control rods balancing the system at supercritical boundaries and may lend itself to more control and robustness. The conventional fission reactor can be scrammed (emergency shutdown) but the reactor cannot then be easily restarted (I think). The issues with heat, radioactive decay heat management, etc would not be changed. As such I am uncertain what is gained by using a fusion moderator for the fission process, except as I mentioned- a perhaps finer and forgiving control.

Beam- beam fusion has advantages, but it is more challenging. If you can focus two opposing beams of fusable ions through a tiny intercept area and have at least some degree of ion repeat passes, even a low density , perhaps below the Brillion limit might produce enough fusion , at least for the fusion/ fission approach. But, if this was easy, then it would have been done long ago. Cathode grid transparency is still a problem. The approach using electrostatic acceleration that avoids this is the Polywell and to a lesser extent some other experiments. A group of MIT graduates tried to do this with focused multiple electrode directed spherical convergence of multiple beams, but they ran out of money and abandoned the effort. I don't know if they made any progress.

I think Boeing has proposed a fusion/ fission hybrid, except they propose laser heated fusion instead of electrostatic heating.

Dan Tibbets

Royce Jones
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Re: Alternative Reactor Design

Post by Royce Jones » Mon Nov 20, 2017 2:49 pm

Better control is one major plus for Fusion/Fission but also there is the potential for fission fuel breeding using the Fusion generated neutrons. For example using UF6, which is a waste product of fission fuel production, the fusion generated neutrons can transmute the U238 into Plutonium. Another example would be transmuting Thorium into U233. So the fusion reactor can more rapidly breed fission fuel. Why would you want to do this? Well, producing energy would be one example, powering a Starship would be another.

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