[FernandoTN]

“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?

[jl6]

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.

[JumpCrisscross]

> has made great scientific progress but still has a lot of engineering left to do

It’s made serious engineering progress too.

[ncmncm]

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.

[JumpCrisscross]

> 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.

[ncmncm]

Bombardment is with hot neutrons.

Period.

[fallingknife]

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/

[ncmncm]

There is no reason to expect that p-11B fusion is possible.

It might be, in a hundred years, if our present understanding is wrong, and somebody figures out how to reflect gamma rays.

[fallingknife]

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?

[Apocryphon]

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.

http://i.imgur.com/sjH5r.jpg

https://hardware.slashdot.org/story/12/04/11/0435231/mit-fus...

[Trouble_007]

Timeline of Nuclear Fusion : https://en.m.wikipedia.org/wiki/Timeline_of_nuclear_fusion