Which fusion has the most chancess for success?

[Breakable]

I think it would be interesting to perform an objective analysis of existing fusion approaches to try to predict which approach will most likely succeed.
I am not a physicist so I would like not to speculate myself, but maybe someone can try to list all the unknowns in each (or at least the one you know best) of the fusion technologies that need to be explored before a net energy reactor can be produced, and also what is the likelihood for them to be positive. Then it would be possible to make a table to compare each approach side by side and calculate the most likely candidate:
Probability_of_success =
(Σ (probability_of_required_breakthrough))/required_breakthroughs_count

Edit:Changed "unknown" to "required_breakthrough"
Edit:Anyone cares to recommend a wiki?

[jnaujok]

...which approach will most likely succeed.

I'll take the easy one -- gravitationally confined fusion.

Chance of success 100%

Examples: Approximately 70 Septillion stars in the visible universe...

(Sorry, couldn't resist.)

[chrismb]

Unfortunately, even gravitationally confined fusion only barely works and has a lower specific output than, say, mammalian bodily mass by a couple of orders of magnitude. viz. running a 2m^3 cow is a better power generator than a 200m^3 'stellar' fusion plasma, and grass is easier to obtain as a fuel than tritum, or 11B, to boot.

I do not think this type of gap-analysis would work for fusion. There are three possibilities;

a) fusion power is impossible,

b) the means to create fusion power already exists, technologically, but no-one has yet 'assembled' the 'correct' elements of the puzzle to make it work,

c) the means to create fusion power does not currently exist and needs a key new finding.

The analysis is therefore erroneous because either a) there's no point, b) it's a case of finding [read; inventing] the one with no issues, c) we're not going to find 'the one' just yet.

[TallDave]

Depends what you mean by "succeed." There's little question we could build really really expensive net power tokamaks, but it's not clear whether that would be useful or economically sensible.

[DeltaV]

There are three possibilities;

a) fusion power is impossible,

b) the means to create fusion power already exists, technologically, but no-one has yet 'assembled' the 'correct' elements of the puzzle to make it work,

c) the means to create fusion power does not currently exist and needs a key new finding.

Actually, there is at least one other possibility;

d) the means to create fusion power already exists, technologically, and has been dark-sided by covert, elitist, reptilian overlords to keep it out of the minds and workshops of the common cattle.

[MSimon]

There are three possibilities;

a) fusion power is impossible,

b) the means to create fusion power already exists, technologically, but no-one has yet 'assembled' the 'correct' elements of the puzzle to make it work,

c) the means to create fusion power does not currently exist and needs a key new finding.

Actually, there is at least one other possibility;

d) the means to create fusion power already exists, technologically, and has been dark-sided by covert, elitist, reptilian overlords to keep it out of the minds and workshops of the common cattle.

how about

e) visitors from another planet in flying saucers already know and won't tell us

[Aero]

e) visitors from another planet in flying saucers already know and won't tell us

That's the same as d.

[KitemanSA]

How about

f) I know what caused the FlashForward.

Oh, sorry, wrong thread!

[MSimon]

e) visitors from another planet in flying saucers already know and won't tell us

That's the same as d.

Modified. No intentional contact. Not overlords. Just monitors.

[DeltaV]

Thank you for not portraying us as invaders.

We are of peace. Always.

Delta'V'

[MSimon]

Thank you for not portraying us as invaders.

We are of peace. Always.

Delta'V'

Well peace for our time then. That is a relief.

[DeltaV]

We will release the Polywell data when your world is ready for it.

[jmc]

Well in terms of achieving ignition, if we are to believe the ICF people, then the national ignition facility will get there in a few years.

(And then ofcourse there's the sun and H-bombs)

But neither approach will produce net plug to socket electricity.

In terms of producing net energy, I think ITER or DEMO will get there eventually (JET got pretty close)

In terms of making fusion cheaper, in my mind its quite simple, if you want a smaller machine, you need a higher field, high beta plasmas provide the most efficient means of confining a plasma, so you want a small high field high beta plasma.

With this in mind, the pulsed compression of beta~1 FRCs are a good candidate for the cheapest way to achieve nuclear. The science behind FRC's is already well-understood (or atleast better understood the focus fusion or Polywells) so I'd agree with Art Carlson in saying they are they best candidates for cheap fusion energy in the near term.

There are quite a few private companies pursuing approaches along this avenue of development:

Helion
http://nextbigfuture.com/2009/04/helion ... -john.html

General Fusion
http://www.generalfusion.com/

I think Tri-Alpha are also doing something along the lines of an FRC though in a different manner.

LANL is doing experiments on FRC compression and hope to achieve fusion plasmas of 1000 Teslas contained in a volume that is merely millimetres across

http://wsx.lanl.gov/mtf.html

[chrismb]

In terms of producing net energy, I think ITER or DEMO will get there eventually (JET got pretty close)

Depends on how you juggle and spin the numbers;

best JET DT pulse;
energy into plasma = 22MJ
energy out of plasma = 18MJ

but

energy required to form the magnetic field = 1GJ

total efficiency = 2%

efficiency required = 1000%

[David_Jay]

Chris:

I have always thought of you as a Polywell skeptic.

I have to apologize, I now see that you are a general skeptic, not a "contained" skeptic

Seriously - keep on challenging everything, iron sharpens iron!