What Could a Fusion 'Breakeven' Reactor Look Like?

[68658]

After poureing over countless fusion related text and information an idea struck me: Why is breakeven, breakeven? If the amount of energy you can extract off of a fusion reaction is highly effiecent and the fusion production method is equaly effiecent, then wouldn't that mean that input to output (breakeven) equality would be lower, and possibly more easly reached or overcome? Assumeing this what other methods could be used to extract power from fusion, photoelectric/photovoltaic effects where first to come to my mind? But then that would mean a fusor could produce "breakeven" assuming one used solar panels and enough lux where created, right? My thought of a "breakeven" reactor design then was to line a large fusor with enough solar cells to power a closed loop solar power production system with fusion opperating componnents tied in. Yet is this even possible? And could it be if not or if so, then with what revisions to the idea?

 

[MisterX]

Fusors made so far have been very far from break even, AFAIK. The fusor is not a promising power producing reactor design due to grid collisions that happen during operation.

The energy produced by fusion reactions will typically be carried by high energy neutrons or light element nuclei. I'm not sure if solar panels would be an appropriate way to harvest this energy. Perhaps photovoltaics could be used to harvest the electromagnetic radiation emitted from the plasma.

High energy nuclei are already electricity, and energy could be obtained from them via something like a particle accelerator in reverse.

Another method is to use fusion to generate heat, and use the heat to generate steam like in a fission plant.

 

[68658]

Heat as way to produce energy is highly in efficeint, thermodynamics is very clear when it comes to energy contained in a susbstance. My thoughts are that breakeven is far less than widley concieved because of the ways energy is created from them, and further most if not all lititure on fusion pretains to tokkamacs and laser detonation fusion. All or most partialy use maxwellian concepts to create fusion, thermoneuclear reactions i should say. In a fusor electrostatic indifferences and potientials cause particle acceleration to the poisor where fusion may or may not occur. Now in a fusor the fusions per second rate are low but what about the light intensities created at super high voltages. Couldn't that biproduct of fusion generate electricity, also don't gamarays exibit god phtovoltaic accurences at less than 50 Kev ranges, which is in the ball park of most IEC machine?

 

[Drakkith]

"Breakeven" in fusion can be taken as one of two things.

A. The point where the heat or energy generated from the fusion sustains the reactions. IE the fusion reactions release more energy than is put into the reaction. (Before inefficiencies during conversion and such are taken into account)

B. The point where the we reach NET energy gain. IE where the energy released during the reaction is not only enough to sustain further reactions, but also to generate electricity through whatever method you use.

Neither A nor B has been reached yet in any reactor. A standard Fusor has been shown to be unable to reach breakeven in all current designs. While further research MIGHT allow it to, the chances are much less than tokamaks and other designs. (I say chances, but I mean that without some type of alteration to the current designs it is not possible)

Also, any light generated from the fusion events does not produce a large amount of energy compared to the kinetic energies of the other products. The light created from the non fusing plasma via high voltage can be recovered, but not fully.

 

[68658]

Ok but... Let's say i build a fusion reactor.

I build a 24 side truncated cube (a 3d octagon of sorts) i line the 14 square sides with solar cells. This is the vacuum chamber, it is 2 feet in diameter each of the square 14 sides measure 10 inches by 10 inches. A solar cell takes up 2 by 2 inches, so I fit 25 cells a square, that comes out to 350 celles total. Each cell produces 0.6 volt amperes of electricity in normal direct sunlight. This equates to 210 volts of electrical energy (if the light intensity is sufficeint). The electriacl energy created here is run to a battery charge regulater that charges a bank of batteries. From this bank a 12V DC to 120V AC sine wave inverter is attached from this now 120V AC a 15 Kw transformer attached to a 1.5 megavolt ampere tesla coil. The 1.5 MvA is then rerouted to the electrostatic grid. The electrostatic grid is comprised of an electromagneticaly protected tube which has the voltage aplied to its outer skin, think polywell just sphereicaly and radialy. Could it work?

 

[Drakkith]

It could work in the sense that you could probably get reactions if you set everything up correctly. But you would still be inputting (from the solar cells) more power than you are getting out of the reactions. You would be better off just using those same solar cells hooked up to a batter or something instead. You would be wasting the energy from the solar cells by hooking them up to a reactor that didn't hit breakeven.

 

[68658]

But yes, what defines breakeven when operateing a machine such as this. By the way this would be a proof of concept, the hoy grail would be to use black body qusicrystals which would abosrb 90% or so of the electromagnetic energy given off.

 

[Drakkith]

What? If the reactor was able to achieve a reaction rate greater than breakeven you wouldn't even need the solar cells. You could simply use part of the energy generated sustain the reactions and the extra as generated power.

 

[68658]

My point is do you really need to have breakeven furion reaction rates, to have a self powered reactor.

 

[Drakkith]

Yes, the reaction needs to be breakeven.

 

[68658]

But what constitues breakeven because under:
"B. The point where the we reach NET energy gain. IE where the energy released during the reaction is not only enough to sustain further reactions, but also to generate electricity through whatever method you use."
It would seem as though you only need enough reactions per second to successfully illuminate a solar array, which I am assuming would be far below "breakeven" of a conventional manner

 

[Drakkith]

You cannot reach B without first reaching A. Period. Do you understand why A needs to happen? This has absolutely nothing to do with solar panels or anything else with equipment. It is purely this: The power input to the reactions needs to be LESS than than the power generated from said reactions, otherwise anything you do to gather the energy won't matter.

Edit: And realize that currently the breakeven point between A and B is about 2-10 times more for B because of inefficiencies in applying the power to the reactions and then gathering the generated power.

 

[68658]

Well youre stateing heat, so i assume youre talking about the average energy conatined with in said matter. So how many eV do you suppose i need?

 

[Drakkith]

I don't understand your question. Could you elaborate?

 

[68658]

Youve stated in A heat needs to be sufficent enough to sustian fusion, so how many eV per barn would you say is break even (though i must point out now that i think about it i think youre thinking on a more thermonuclear fusion basses, and I am thinking on a more inertial electrostatic confinement fusion basis)

 

[Drakkith]

The eV of the fuel only determines the cross section, aka how likely they are to fuse. Too little and they can't get close enough, too much and the cross section is reduced so far there is practically no fusion. The window of optimum eV is different depending on the fuel. The entire issue with the reactors aren't that they can't generate enough eV to cause the fuel to fuse, it is generating the required eV efficiently. That depends on multiple things such as confinement time of ions and electrons, density of the fuel, etc.

Currently we cannot do this.

Edit: The average kinetic energy of the fuel is also a measure of the heat. You can use eV or temperature.

 

[68658]

I argue we can D+T reaction has the lowest cross section through clever electrical engenering and the use of the most easly fused isotopes we can easly generate net power.

 

[russ_watters]

This is silly. If it were that easy, it would already be done. Locked.