Thread: Latest Fusion News : National Ignition Facility achieves 70% of the laser energy delivered to the fuel capsule.

BBC News reports a new NIF record in fusion research*. Quoting from the article:

"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."

More from the article:

"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."

Sounds like they are getting a lot closer to break-even. Don't know a lot about the details of these reactors, but the results sound encouraging.

The 70% yield increases previous attempts "eight times NIF's previous record, established in Spring 2021, and 25 times the yield from experiments carried out in 2018."



"US lab stands on threshold of key nuclear fusion goal"

* https://www.bbc.co.uk/news/science-environment-58252784

Main problem (for both NSF and Tokamack) has always been engineering, not science. How to build a machine that is useful, not just demonstrates.

Originally Posted by mathman

Main problem (for both NSF and Tokamack) has always been engineering, not science. How to build a machine that is useful, not just demonstrates.

By useful, you likely mean how to convert the excess energy into electricity, etc.

"Demonstration" simply proves an excess of energy from a self-sustaining reaction.

How much more complicated is all this supposed to be? Most of us just assumed the excess energy would be "useful" as it is being produced, not thinking of the means for using it.

At 100 million K, it is a rather hot plasma, after all......

I think one of the perspective directions could be combination of dense plasma focus with a femtosecond or picosecond laser. It could be much cheaper than NIF as it may use just one or few lasers instead of hundreds and there is no need to prepare expensive targets (hohlraums). The first experiments of that kind had been conducted in 1970-th, but there were no powerful picosecond lasers back then.
Soft X Rays from a Laser‐Heated Dense Plasma Focus: Journal of Applied Physics: Vol 42, No 13 (scitation.org)
Now it may work much better.

Originally Posted by Double Helix

Originally Posted by mathman

Main problem (for both NSF and Tokamack) has always been engineering, not science. How to build a machine that is useful, not just demonstrates.

By useful, you likely mean how to convert the excess energy into electricity, etc.

"Demonstration" simply proves an excess of energy from a self-sustaining reaction.

How much more complicated is all this supposed to be? Most of us just assumed the excess energy would be "useful" as it is being produced, not thinking of the means for using it.

At 100 million K, it is a rather hot plasma, after all......

What I simply meant as "useful" is building a power plant to generate electricity at a sensible cost.

Originally Posted by mathman

What I simply meant as "useful" is building a power plant to generate electricity at a sensible cost.

The whole technical aspect of constructing a functional power plant from a fusion reactor reminds me of the thread on fusion powered spaceships. Read a lot of "ideas" of this on other threads, and sci-fi movies, but no one seems to have a way of converting the high temperature plasma into useful applications. We have no materials available to deal with such high temperature forms of energy, other than containment of the plasma to permit fusion.

Was hoping that someone with more knowledge of harnessing fusion power could tell us how this might be accomplished for a working power plant. Turning water into steam sounds very practical, but how would this be accomplished from such high reactor temperatures?

So the question remains:

You have a successful self-sustained fusion reactor running at 100 million K. How do you build a facility to convert the extra energy for some kind of power plant? It almost seems more difficult than developing the reactor itself. One needs to access the plasma directly or indirectly to obtain some functional mechanism to use the energy. Sounds like a need for a controlled "leaky" mechanism to harness a fusion reactor's output at manageable temperatures somewhere in the "leak stream".

Probably reasonable to assume we won't be seeing these for a while.

Originally Posted by Double Helix

We have no materials available to deal with such high temperature forms of energy, other than containment of the plasma to permit fusion.

This is not so much problem with inertial fusion, as there is no need for a solid container walls. One of the concept is a "lead waterfall", under which there are liquid, not solid walls. The walls cannot melt as they are already molten. Lead in liquid form is both energy carrier and protects external walls from damaging radiation. External walls could be made of some radiation resistant material such as Boron, but not necessarily made of metal.