Viewing 6 posts - 16 through 21 (of 21 total)
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  • #13348
    Impaler
    Participant

    My simplistic math based on the numbers off Tim1’s Sankey flowchart shows that the combined collector efficiency is expected to be 80% and each collector is individually also shown at 80%.

    Furthermore if efficiency of the combined power collection drops to below 61% then their is no longer a net surplus for the grid (the device would just manage to maintain self-cycling while throwing off lots of heat). If we assume 80% for the beam collector (the more mature technology) then the X-ray collection needs to be greater then 33% to still produce net power.

    Naturally the net power output increases with higher efficiency, for each 1% increase in combined efficiency above the 61% floor the total net power output to grid increases by 263 kw or about 1/4 of a MW.

    Any increase in Fusion output / input energy would of course change the break even points considerably.

    #13349
    nemmart
    Participant

    zapkitty wrote:

    The thermal output of an FF unit operating at 200 Hz has been estimated at ~7 MW thermal… doable, but pushing things a bit.

    Initiating each shot requires 100 KJ from the capacitors. If the conversion efficiency is low (say 40%) then you won’t get enough energy from each shot to recharge the capacitors for the next shot. And the shots/sec is irrelevant.

    The question is core temperature and so the results will be the same whether you increase the shot rate or the energy per shot.

    The final set of beryllium electrodes will be quite a bit smaller than the old copper and current tungsten designs. Less mass and closer to the plasmoid. Increase the temperature too much [em]and the anode is going to be slag.[/em]

    nemmart wrote: A plan B designed around a lower conversion efficiency would require far more energy from the fusion reactions, something like 400 KJ per shot instead of the planned 66 KJ.

    That would, of course, mean switching from an aneutronic to a neutronic process. Switching from pB11 fuel to D-T fuel… from hydrogen-boron to deuterium-tritium .

    And that just means that the anode will not only be slag but the entire FF core will be highly radioactive for centuries to come. Not very good for the FF project.

    The temptation of D-T… the low-hanging but extremely radioactive fruit of the fusion fuel tree.

    Interesting aside: EMC2’s Polywell project recently seems to be trying to use the prospect of D-T fuel to lure in investors… which seems odd since D-T’s intense high-energy neutron flux would quench the HTSC coils a Polywell power generator would need to function.

    Oh come on Zap, why would you assume that the only way to increase the fusion output beyond 66 KJ is by changing to D-T fuel? There are more parameters that can be tweaked than just the fuel. Why not go to a higher power like 3 MA, perhaps by increasing the capacitor voltage, or going to 15 capacitors instead of 12? See, I don’t know the various parameters that can be tweaked and what the real physical limitations are. But there must be someone on the forums who does know the parameters and could formulate a realistic plan B.

    #13351
    zapkitty
    Participant

    nemmart wrote:
    Oh come on Zap, why would you assume that the only way to increase the fusion output beyond 66 KJ is by changing to D-T fuel?

    Would you believe it was your statement of the need to increase the fusion gain by a factor of 6? 🙂

    nemmart wrote: There are more parameters that can be tweaked than just the fuel…

    But they all amount to increased heat in the core… unless you’re postulating some currently unknown mechanism that will lead to a far more efficient fusion process than is currently envisioned?

    While there is some flexibility there, some leeway towards a core that is a bit hotter or a bit cooler, there is just not near enough margin to septuple the output without melting the core.

    #13352
    nemmart
    Participant

    zapkitty wrote:

    Oh come on Zap, why would you assume that the only way to increase the fusion output beyond 66 KJ is by changing to D-T fuel?

    Would you believe it was your statement of the need to increase the fusion gain by a factor of 6? 🙂

    nemmart wrote: There are more parameters that can be tweaked than just the fuel…

    But they all amount to increased heat in the core… unless you’re postulating some currently unknown mechanism that will lead to a far more efficient fusion process than is currently envisioned?

    While there is some flexibility there, some leeway towards a core that is a bit hotter or a bit cooler, there is just not near enough margin to septuple the output without melting the core.

    Well, if the scaling law is roughly the current to the 5th power, then a raising the fusion output by an additional factor of 6 might not be that big of a deal. It might be far easier to raise the fusion output by a factor of 6 than to hit the conversion efficiency targets of 80-90%.

    And in terms of heat, if you raise the fusion output, just slow down the shot rate so you don’t overheat the core.

    #13751
    Engineer
    Participant

    Hi I am new to this site. I think high temp thermoelectric converters are the simplest way to use waste heat. Not sure what X-rays do to them.

    #13783
    JimmyT
    Participant

    If the onion and ion beam capture hit the 80-90% targets then everything will be just peachy.

    But I’ve been following this project for a while and there are more twists and turns than a
    mountain road. Switch problems that had to be overcome, arcing issues, plasma impurities,
    and several redesigns of the cathode and anode…

    >I agree with you completely about the twists and turns, but I wonder if the difference in this research project is that Eric is very open and public with not just his successes, but his setbacks too. Eric is very WYSIWYG.

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