[Lex Computer & Tech Group/LCTG] Nuclear fusion...

Tue Dec 13 14:37:41 PST 2022

More complicated even than that

Here's how they did their calculation and what was omitted

Fusion Energy calculated from
fast neutrons leaving the target chamber of the NIF -- 14.1 MeV per fusion
threw in the 3.5 MeV carried off by the "Hot" alpha particle [Helium
nucleus]
so each fusion reaction which occurred yielded a total of 17.6 MeV
estimated the total amount of fusion fuel in the diamond walled capsule
the claim is that the "fusion burn" yielded 3.15 MJ of fusion energy --
corresponding to  1.1e24 fusions during the "burn"   [1MeV = 1.60218e-19 MJ]

Trigger Energy due to the 192 Lasers [1 pulse each] deposited into the
Hohlraum containing the target capsule --- 2.05 MJ
that gives a Q of 1.5
most expansive [optimistic definition] only 250 KJ of the 2.05 MJ of UV
actually contributed to compressing the target capsule
that gives a Q of 12.6
even less of the x-rays produced in the hohlraum actually successfully2100
coupled to the actual target pelet -- perhaps 10 to 15 KJ
that gives you a "Star Wars" Q = 2100

Of course if you account for the amount of electrical energy needed to
produce the laser pulse -- things are a bit more pessimistic]
300 MJ was used to pump the Neodymium Glass disks which produced the IR
pulses that were up-converted to UV [about 50% overall conversion
efficiency]
that would be a Q = 1.05e-2

Ted

from Physics Today
DOI:10.1063/PT.6.2.20221213a
13 Dec 2022 in Politics & Policy
National Ignition Facility surpasses long-awaited fusion milestone
The shot at Lawrence Livermore National Laboratory on 5 December is the
first-ever controlled fusion reaction to produce an energy gain.
David Kramer
https://physicstoday.scitation.org/do/10.1063/PT.6.2.20221213a/full/

The yield surpasses the criteria for ignition established by the National
Research Council in 2007.
By other measures, such as the amount of energy deposited on the fuel
capsule—around 250 kilojoules—the gain, or Q, is around 10, says Michael
Campbell, who led NIF construction until 1999.

According to Mark Herrmann, program director for weapons physics and design
at LLNL, a laser shot performed on 5 December produced about 3.15
megajoules of fusion energy from the 2.05 MJ of laser light that reached
the small cylindrical chamber known as a hohlraum, which converts the UV to
x rays. Suspended inside was a diamond-coated, peppercorn-size capsule
containing deuterium–tritium fuel, which the x rays imploded.

Yet the amount of fusion energy from the record shot amounts to just 1% of
the 300 MJ from the grid that’s required to power the 192-beam NIF laser,
Herrmann says. Thus, although the lab’s achievement is a significant step,
inertial fusion is still a long way from becoming a viable energy source.

On Tue, Dec 13, 2022 at 4:28 PM Michael Alexander <mna.ma at yahoo.com> wrote:

> Carl,
>
> We could take your remark even further, Carl.  The “shot” on Dec 5 was far
> from the “first controlled fusion experiment in history”:  It was the
> first in which the energy of fusion exceeded the energy of the pulsed laser
> beams that initiated the fusion.  (Preceding experiments failed.)
>
> We language snobs should, however, be consoled by the fact that the
> general public probably understood what the LLNL/DOE people were *trying*
> to say.
>
>     – Mike Alexander
>
> On Tuesday, December 13, 2022, 4:02 PM, carllazarus at comcast.net wrote:
>
> I read that “The LLNL said a team at its National Ignition Facility (NIF)
> conducted the first controlled fusion experiment in history on December 5,
> achieving what is known as "scientific energy breakeven."”
>
> What is counted in “scientific energy” and what does it omit?
>
>
>
> -- Carl
>
>
>
> *From:* LCTG <lctg-bounces+carllazarus=comcast.net at lists.toku.us> *On
> Behalf Of *Ted Kochanski
> *Sent:* Monday, December 12, 2022 7:32 PM
> *To:* Drew King (dking65 at kingconsulting.us) <dking65 at kingconsulting.us>
> *Cc:* Lex Computer Group <lctg at lists.toku.us>
> *Subject:* Re: [Lex Computer & Tech Group/LCTG] Nuclear fusion...
>
>
>
> All,
>
>
>
> Be careful about Hype versus simple reality
>
>
>
> Yes it does appear that LLNL National Ignition Facility may have hammered
> a poor defenseless target pellet into producing more fusion energy than was
> absorbed by the pellet
>
> so technically Q>1 [about 1.2]
>
>
>
> BUT -- and I'll admit a bias toward Magnetic Confinement Fusion -- the
> Energy used to produce the Energy delivered to the pellet was not part of
> the calculation
>
>
>
> While Magnetic Fusion with Superconducting Magnets in a Tokamak
> configuration probably need Q>2 to be a credible Eureka Moment -- The
> energy needed to fire the lasers probably needs a Q>30
>
>
>
> Ted
>
>
>
>
>
> On Mon, Dec 12, 2022 at 5:30 PM Drew King (dking65 at kingconsulting.us) <
> dking65 at kingconsulting.us> wrote:
>
> All,
>
> The Verge: A “scientific breakthrough” in nuclear fusion? How to watch the
> announcement tomorrow.
>
> https://www.theverge.com/2022/12/12/23505416/nuclear-fusion-scientific-breakthrough-how-to-watch-announcement-biden
>
> --
> Drew King
>
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