
Unexpected electric current that could stabilize fusion reactions discovered - bookofjoe
https://phys.org/news/2020-09-unexpected-electrical-current-stabilize-fusion.html
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Animats
A big problem with fusion systems has always been stabilizing the plasma.
Stars do it with gravity, which pulls inward only. Doing it with magnetic
fields requires fancy geometry to try to get the effect of a uniform inward
push. None of the approaches are all that great.

A few groups have tried active stabilization of plasma. It's being planned for
China's new tokomak.[1] The instabilities are on the order of milliseconds,
not too fast for active control. This new development may advance that work.
Maybe. Possibly.

[1]
[https://www.sciencedirect.com/science/article/abs/pii/S09203...](https://www.sciencedirect.com/science/article/abs/pii/S0920379619306994)

~~~
njarboe
What is interesting is that one can use current in the plasma itself (which
creates a magnetic field) to confine the plasma, if one can control the
current well enough. This design [1] does that. Unfortunately DOE funding for
new fusion concepts has been almost zero for many decades and ITER has further
depleted the DOE research fusion. On the bright side there has been some
recent VC funding in the space and CTFusion is working on this design
concept[2].

[1] [https://spectrum.ieee.org/energy/nuclear/inside-the-
dynomak-...](https://spectrum.ieee.org/energy/nuclear/inside-the-dynomak-a-
fusion-technology-cheaper-than-coal)
[2][https://ctfusion.net/technology/](https://ctfusion.net/technology/)

~~~
sbierwagen
Yes, confinement by running a current through the plasma is well known. First
use was by the ZETA experiment in 1957.
[https://en.wikipedia.org/wiki/Z-pinch](https://en.wikipedia.org/wiki/Z-pinch)

The eternal problem in science journalism: a scientist will explain how their
machine works, and the journalist will get the impression that they have
independently invented each part of the apparatus, with no prior art. The
incentives encourage it: the scientist wants to take credit for everything
possible, and the journalist wants to report on a maximally new and exciting
machine.

~~~
njarboe
I agree, a journalists description of such new fusion concept is unlikely to
be useful to people trying to understand what is new about the concept. I am
not a fusion scientist, but my dad is the "Tom Jarboe" in the article. From my
limited understanding from talking to him, the main reason that they think the
dynomak design has a chance of working is because they solved the problem of
adding energy to a stable plasma without disrupting it by using a new type of
helicity injector. Not sure if it would really work, but hopefully they can
get enough funds to try.

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eximius
The title is terrible, but what is interesting to me is whether this could
allow the _direct_ draw of power from a nuclear reactor, instead of just
through heat.

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soperj
How much more power would you get from a direct draw vs just through heat?

~~~
iaw
Thermal efficiency in the Rankine cycle (which powerplants apparently
leverage) is around 30%.

So it sounds like there's a lot of potential improvement. Of course, given
we're talking fusion and not fission any power plants are purely hypothetical
at the moment as all publicly known fusion facilities are for research.

~~~
falseprofit
>publicly known

Do you feel that this is an important qualifier?

~~~
iaw
Energy generation is a national security concern. While all signs point to
engineering issues preventing creation of a successful fusion plant, the
reality is there are only a small handful of issues left that prevent energy
generation from fusion.

The Lockheed SR-71 Blackbird first flew in 1964, the titanium used for its
construction was purchased in secret via front operations by the CIA from the
USSR. The Soviet Union was the only country that had enough titanium to build
the SR-71.

The reason I reference this is because with enough money and resources
anything is possible to do in secret. The SR-71 included some revolutionary
technological innovations to solve the problems created by super-sonic flight.
Energy viable controlled fusion is a little farther than the SR-71 was but not
so much so that it is impossible.

Hence the qualifier.

~~~
falseprofit
Thanks for the interesting historical example!

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Booktrope
The writing is really horrible.

Interactions of waves in plasma "conspire" to produce effects.

Electrons ride waves like "surfers".

Interesting findings, extremely badly presented.

~~~
lambdatronics
Phys.org is the Applebee's of science journalism -- they warm over some canned
press release topped with a thin sauce of quotes from the co-authors (they
can't be bothered to get someone independent to comment).

In fact, this wasn't even written by phys.org staff -- it was from the
Princeton PR department.

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_trampeltier
What is a low and what is a high frequency. It would be nice if there would be
some kind of numbers in such texts.

~~~
iaw
It's probably in the original paper if you have access

[https://aip.scitation.org/doi/10.1063/5.0011516](https://aip.scitation.org/doi/10.1063/5.0011516)

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hinkley
Do we understand how the magnetic fields in stars work?

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datameta
Depends on which stars. We recently discovered through relativistic ray
tracing of x-rays that neutron stars may have more than two magentic poles and
as such two poles may even be located quite close to one another in the same
hemisphere. There really is much left to discover about them!

[https://ui.adsabs.harvard.edu/abs/2019ApJ...887L..21R/abstra...](https://ui.adsabs.harvard.edu/abs/2019ApJ...887L..21R/abstract)

