US lab stands on threshold of key nuclear fusion goal
By Paul Rincon
Science editor, BBC News website
A US science institute is on the verge of achieving a longstanding goal in nuclear fusion research.
The National Ignition Facility uses a powerful laser to heat and compress hydrogen fuel, initiating fusion.
An experiment suggests the goal of "ignition", where the energy released by fusion exceeds that delivered by the laser, is now within touching distance.
Harnessing fusion, the process that powers the Sun, could provide a limitless, clean energy source.
In a process called inertial confinement fusion, 192 beams from NIF's laser - the highest-energy example in the world - are directed towards a peppercorn-sized capsule containing deuterium and tritium, which are different forms of the element hydrogen.
This compresses the fuel to 100 times the density of lead and heats it to 100 million degrees Celsius - hotter than the centre of the Sun. These conditions help kickstart thermonuclear fusion.
An experiment carried out on 8 August yielded 1.35 megajoules (MJ) of energy - around 70% of the laser energy delivered to the fuel capsule. Reaching ignition means getting a fusion yield that's greater than the 1.9 MJ put in by the laser.
https://www.bbc.co.uk/news/science-environment-58252784
FlashDangerpants wrote: ↑Sun Aug 15, 2021 12:56 am
You mark your own homework very leniently...
that's what a feasibility study looks like...
what you've got is pretty much a daydream!
You would have years of R&D before you were ready to begin a feasibility study.
What's interesting is the degree to which intellectual curiosity informs research agendas - as opposed to practical goals, for it would seem, strangely in the case of fusion - there's a co-incidence of a scientific challenge inherent to nuclear physics, and national security interests, vis a vis energy policy, that has kept the project alive - like some oft reanimated corpse. Nuclear fusion has held out the promise of limitless clean energy since 1932 - and it still doesn't work. Nonetheless, governments are still funding research into fusion on the basis fusion promises limitless clean energy.
My layman's impression of the field is that fusion cannot work in earth gravity. It's the enormous gravitational force of the sun that overcomes the Exclusion Principle and allows for sustained fusion reactions. Simply pumping in massive amounts of energy, to create pressure, to, effectively crash atoms into each other and fuse - is not the same as atoms being crushed together by the gravity of the sun. In each case, the Exclusion Principle is overcome - but only under gravity is there a sustained reaction. After any single fusion event in an 'energy forced' system, it returns, mathematically - to the same probabilistic state that two atoms will crash randomly together, whereas, under massive gravity, the occurrence of fusion increases the probability of fusion. In gravitationally induced fusion, atoms are packed tightly together, then crushed further by ongoing fusion energy events - to overcome Exclusion. They are not excited by absurd temperatures, costing vast amounts of energy - as if to cause sufficient random collisions to sustain fusion. Ergo, fusion can be made to occur, but it cannot be sustained, nor produce more energy than it consumes in earth gravity.
I have no way of checking whether these impressions are correct. What I do know is that after 90 years - holding out the promise of limitless clean energy, it might be wise to also look elsewhere - and isn't the earth a massive ball of molten rock? I thought so - but admittedly, I'm no scientist! I'm just interested in science.
https://en.wikipedia.org/wiki/Timeline_ ... ch%20other.
