Mostly Agreed: there may be applications such experimental astrophysics, but that's certainly not the main motivation.
> 2. It has no consequence for any civilian project. The target that produced a couple of MJ cost $10M. (2.4 MJ is <0.7 kWh.) A real plant would need to feed them in at a high rate. Q is not the important measure. Dollars out / dollars in is the right measure, and everyone is still at exactly zero, with no plausible prospect of ever exceeding 1.
The cost of just about anything new regarding fusion experiments is not very meaningful: likely it had to be invented, designed and manufactured just for them. Of course it's crazy expensive, but it doesn't mean prices won't go down after an industry around fusion has been established. Just look at the price of a c-Si solar cell in the 70s.
> 5. No research has gone into identifying a viable material, in decades, despite that none is known. After a short time the reactor parts would all become weak and (also) fiercely radioactive.
I don't know about inertial confinement, but in magnetic fusion that is completely false. Materials with low activation, radiation damage resistance and good plasma properties have been continuously researched for the last 30 years: the current candidate for ITER is EUROFER97 for which you can find almost 800 publications. [1]
> 5. Repairs would need robots not yet designed.
Also false. Not only there are several remote handling designs for DEMO power plants, but they have also existed for a long time. For example, JET had been operated remotely since 1997, during the DT1 campaign. [2]
> 6. Civil fusion would require a large amount of tritium, which no one knows how to make economically.
Well, this is dishonest. Of course no one knows how to breed tritium economically: we don't know what the economy will look like in 40-50 years, but we surely know how to do it.
Fusion power plants are designed for self-sufficiency, producing more tritium that they consume by a factor of at least 1.05 (called tritium breeding ratio). Very briefly, this involves a breeding blanket that converts lithium to tritium and a complex chemical plant to extracts newly produced tritium from the blanket and also recovers it from the unburnt plasma fraction. See [3] for an overview of various design that will be tested in ITER.
For as long as there are a few CANDU reactors around, the current tritium supply will be enough to bootstrap future fusion plants without expensive ad-hoc production. [4]
[1]: https://www.journals.elsevier.com/nuclear-materials-and-ener...
[2]: https://yewtu.be/watch?v=hg6MnjG7m6U
