No, it has not. Apart from stars and thermonuclear weapons, there are no fusion reactions that yield more energy than they require, i.e. the achieve break-even. It has not happened.
That's true, but irrelevant. Producing more energy from the reaction than was required to start the reaction is a different thing from ending up with more total energy in the system than you started with. Even stars don't do that- they just have sufficiently good containment that they don't lose all of the initial ignition energy, and thus don't need additional power inputs to replace non-existent losses.
You seem to be confusing the total power available in a fusion system with the total power available at the output terminals of a generator. The first is relevant to a rocket. The second is not.
To date, energy recovery inefficiencies for fusion reactors have always been high enough that the energy lost to neutrinos / waste heat / etc. is large than the amount produced by the reaction, meaning that the power available at the output terminals is less than the input power. Break-even does not necessarily mean that the reaction itself produces more power than the ignition apparatus- it means that the total useful power you can extract from the system, whether you put it there to begin with or not, is larger than the power required by the ignition apparatus. But a rocket doesn't care about recovery. Any power produced by the fusion reaction counts as a gain.
So in a hypothetical reactor that requires 1000 watts to sustain fusion but produces 250 watts of fusion power, only the 250 watt fraction is exploitable -- the original power must be reserved for heating the plasma. That's why break-even is essential.
You are implicitly assuming that some of the 250W surplus can be extracted, but that none of the original 1000W can. That's a physically indefensible assumption. If you put in 1000W and the reaction generates 250W, then there's a total of 1250 indistinguishable watts running through the system, and you need to be able to harness at least 1000W to keep the system in steady state. If you can extract more than that, you've got a generator.
To date, there have been no -- that's NO -- laboratory fusion generators that produce more power than they require for initiation.
I made no claim that there were. I said that research into this kind of fusion generator has been done, not that it has resulted in a working generator yet. See, e.g., focus fusion, or magnetoplasmadynamic generators.
>> No, it has not. Apart from stars and thermonuclear weapons, there are no fusion reactions that yield more energy than they require, i.e. the achieve break-even. It has not happened.
> That's true, but irrelevant.
That's the topic of discussion. Therefore it is relevant.
> Break-even does not necessarily mean that the reaction itself produces more power than the ignition apparatus ...
That is exactly, precisely what it means. That is how break-even is defined.
Quote: "The fusion energy gain factor, usually expressed with the symbol Q, is the ratio of fusion power produced in a nuclear fusion reactor to the power required to maintain the plasma in steady state. The condition of Q = 1 is referred to as breakeven."
Any questions?
> You are implicitly assuming that some of the 250W surplus can be extracted, but that none of the original 1000W can.
I am not implicitly assuming anything. In the example, because 1000 Watts is required to sustain the plasma in a fusing state, none of that power is available for any other purpose -- it might as well not exist. An attempt to harvest any part of that power will extinguish the fusion reaction. This leaves 250 watts. Those are the facts.
> That's a physically indefensible assumption.
Okay, you need to learn basic physics. One cannot harvest more than 250 watts from the hypothetical system without extinguishing the reaction. The original 1000 watts is unavailable -- it might as well not exist.
>> To date, there have been no -- that's NO -- laboratory fusion generators that produce more power than they require for initiation.
> I made no claim that there were.
Yes, you did. That was your claim -- that fusion reactors produced more power than they required for initiation. Here's what you said:
> Thus, if you can do fusion at all, you will end up with more total energy than you started with.
It is false. While the reaction is underway, you do not have more total energy than you started with, you have less. I have explained why this is so, very clearly.
You simply are not even reading. Nobody said anything about maintaining any steady state. That's needed for a generator. This project is talking about doing one off detonations.
Have you heard of a hydrogen bomb? If they lost energy to creating the fusion in a hydrogen bomb, what would be the point? If you removed the fusion part of a hydrogen bomb, would you get a bigger explosion? No. You get MORE ENERGY using fusion. However, we don't have a way to harness that to make electricity yet to maintain a steady reaction. But maintaining a steady reaction is not what this project proposes doing. Do you get it yet?
Edit: smaller explosion -> bigger explosion. So many explosions.
And your evidence is that I quoted everything that I replied to, word for word, and quoted from the original NASA project documents as well?
> Nobody said anything about maintaining any steady state.
I did, and so did NASA. You missed its significance. Pulsed systems have an average power level, and a peak power level. Both need to be analyzed.
> That's needed for a generator.
Yes, and NASA wants a net generator of energy, something better than break-even, otherwise it's not worth doing. And they say this in their documents about the project.
> This project is talking about doing one off detonations.
I can't believe you missed the significance of NASA'a remarks about break-even. Don't you understand that, pulsed or not, break-even still has a meaning, and if they can't get to break-even, the project makes no sense?
A steady state generator either does or doesn't achieve break-even. A generator that consists of a series of pulses also does or doesn't achieve break-even. Here's what NASA has to say about this:
Quote: "A subscale, laboratory liner compression test facility will be assembled with sufficient liner kinetic energy (~ 0.5 MJ) to reach fusion breakeven conditions."
I can't believe NASA thinks break-even is an essential program goal. Maybe they should hire you as a consultant, so they won't waste taxpayer dollars trying for break-even, after all, according to you, because the output is pulsed, break-even has no meaning.
> But maintaining a steady reaction is not what this project proposes doing.
You very clearly do not understand the relationship between peak and average power. The device being described generates a series of pulses, but for there to be a point to the exercise, the average output power must exceed break-even.
A radar has a peak output power of two megawatts and a steady-state input power of ten watts. Does the radar violate the principle of energy conservation? Yes or no?
A fusion reactor has a peak output power of two megawatts and requires an average plasma sustaining power of 200 KW. Such a generator either does or does not achieve break-even over time, and as quoted above, NASA cares very much which is so.
> But maintaining a steady reaction is not what this project proposes doing.
You need to learn the relationship between peak and average power. Stop embarrassing yourself.
You seem to be confusing the total power available in a fusion system with the total power available at the output terminals of a generator. The first is relevant to a rocket. The second is not.
To date, energy recovery inefficiencies for fusion reactors have always been high enough that the energy lost to neutrinos / waste heat / etc. is large than the amount produced by the reaction, meaning that the power available at the output terminals is less than the input power. Break-even does not necessarily mean that the reaction itself produces more power than the ignition apparatus- it means that the total useful power you can extract from the system, whether you put it there to begin with or not, is larger than the power required by the ignition apparatus. But a rocket doesn't care about recovery. Any power produced by the fusion reaction counts as a gain.
You are implicitly assuming that some of the 250W surplus can be extracted, but that none of the original 1000W can. That's a physically indefensible assumption. If you put in 1000W and the reaction generates 250W, then there's a total of 1250 indistinguishable watts running through the system, and you need to be able to harness at least 1000W to keep the system in steady state. If you can extract more than that, you've got a generator. I made no claim that there were. I said that research into this kind of fusion generator has been done, not that it has resulted in a working generator yet. See, e.g., focus fusion, or magnetoplasmadynamic generators.