“Nuclear fusion is 30 years away; and always will be." I wonder how this phrase manages to hold after 50 years since its inception.
We could compare it to the state of general AI, but at least in the machine learning field, progress is being made without knowing the feasibility or path to reaching general in AI. In fusion it appears that the theory has already been set and maintaining the chain reaction going for long enough is the limitation (progress being made here), would it be the same case that the final steps are still missing without a clear path, or would the current progress be enough to eventually reach it?
AI research has made slow scientific progress but great engineering progress. Fusion has made great scientific progress but still has a lot of engineering left to do.
Engineering work halted 30+ years ago. There has been no recent work on structural materials that could withstand the neutron bombardment, and no work on extracting bred tritium at parts per billion concentration from thousands of tons of "blanket" material needed for the next day's operation.
There is no possibility of any present scheme operating at even 10x the cost of fission. Fission is not today competitive, and falls further behind each day.
> Engineering work halted 30+ years ago. There has been no recent work on structural materials that could withstand the neutron bombardment
We've made massive strides compacting designs, thereby transforming their unit-economic envelope, using low-temperature superconducting magnets. Those magnets continue to improve, driving potential gains in designs faster than experiments can be funded and built. Optimizing for structural materials, or even blanket versus replaceable structure, seems premature when we don't know the parameters or even type of bombardment we'd be working with.
You can get around the tritium problem with boron-proton fusion. Also gets around the inefficiency of converting to heat / turbines. Obviously not any closer to production (and probably further) than tritium fusion, though. https://hb11.energy/how-it-works/
It's been done by firing lasers at a HB pellet, so I assume you mean not possible to be done commercially? And why would you have to reflect gamma rays?
Obviously you can fuse about anything by accelerating nuclei at each other fast enough. If it takes more energy to do it than you can get back, it is of purely academic interest. Firing lasers comes up many orders of magnitude short.
Another alternative is magnetic confinement, but radiative loss goes up with the 4th power of temperature, so would be 10000 times as much as for a D-T plasma, IIUC.
This chart rests upon faulty assumptions about the efficacy of tokamaks, but it does demonstrate how little interest the U.S. federal government has had towards research of fusion.
We could compare it to the state of general AI, but at least in the machine learning field, progress is being made without knowing the feasibility or path to reaching general in AI. In fusion it appears that the theory has already been set and maintaining the chain reaction going for long enough is the limitation (progress being made here), would it be the same case that the final steps are still missing without a clear path, or would the current progress be enough to eventually reach it?