
Here be Fusion – A Visit to General Fusion - curtis
http://wavewatching.net/2013/12/30/here-be-fusion/?1
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DaniFong
Would love to be pointed towards any kind of mathematical analysis of this at
all. There's a really big problem -- you need high ion temperatures to achieve
fusion, but it's electron pressure that's transfered by a shockwave, and
therefore it should be electron temperature that will increase. It takes on
the order of seconds for electrons to transfer their heat -- of a temperature
of hundreds of millions of degrees kelvin to ions.

Can a spherically compressed high pressure concentration really maintain
itself for the time required to heat the ions?

A good treatment of this is in the 1978 Nobel Prize Lecture of Soviet
physicist Pyotr Kapitsa

[http://www.nobelprize.org/nobel_prizes/physics/laureates/197...](http://www.nobelprize.org/nobel_prizes/physics/laureates/1978/kapitsa-
lecture.pdf)

~~~
ihnorton
The idea is to run just below the Bohm limit (see eg pg 13 in [1]), where the
temperature and density required is much lower than that for Tokamak-style
inertial confinement fusion. They adiabatically pre-heat and then inject a
field-reversed configuration plasma immediately before implosion. So the
plasma is at thermal equilibrium and the magnetic confinement minimizes
conductivity loss during implosion.

Los Alamos has an MTF program that has demonstrated fusion under these
conditions, and there are several other programs. See [2] and [3] for recent
experimental and simulation results (different driver mechanism, but same
ignition region).

[1]
[http://fire.pppl.gov/fpa04_wurden.pdf](http://fire.pppl.gov/fpa04_wurden.pdf)
[2]
[http://fire.pppl.gov/IFE_NAS3_MTF_Wurden.pdf](http://fire.pppl.gov/IFE_NAS3_MTF_Wurden.pdf)
[3]
[http://sites.apam.columbia.edu/SMproceedings/11.ContributedP...](http://sites.apam.columbia.edu/SMproceedings/11.ContributedPapers/11.Thio_etal.pdf)

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addisonj
a bit of background about this tech (as understood by a non-physicist)

1\. Take a big metal ball and surround it by a whole bunch of synchronized
pistons

2\. Fill said ball with molten metal

3\. Fire a wave of plasma from both ends of the ball

4\. Time the firing of the pistons so that the plasma and pressure wave from
the pistons all meet in the center and create the conditions necessary for
fusion to occur.

While it isn't yet proven, if this method works it would be quite a bit
simpler than the other lines of research into fusion reactors which require
massive arrays of magnets to suspend plasma and exotic materials that don't
exist yet.

I have no idea if this is actually feasible, but it sure sounds cool!

~~~
pm90
This makes me wonder: what are the current constraints on fusion reactors? I
mean, I had heard that the problem is that the current reactors consume more
energy than they produce. Is that the case or is it just not possible to get
fusion in the laboratory?

~~~
arethuza
It's actually pretty straightforward to create fusion:

[http://en.wikipedia.org/wiki/Fusor](http://en.wikipedia.org/wiki/Fusor)

The catch is doing it in a way that actually produces a surplus of energy that
isn't a bomb. NB Even with bombs, most H-bomb designs actually get more energy
from fission than fusion.

Edit: I wish there was some rule that said that a small percentage of mega-
projects like ITER had to be used to fund competing approaches like this.

[http://en.wikipedia.org/wiki/ITER](http://en.wikipedia.org/wiki/ITER)

~~~
maaku
While we are completely off topic, for those who are interested: an H-bomb
typically originates more energy from does get more energy from fission than
fusion, but the fissile energy is converted into more destructive forms by the
fusion reaction. Much of the destructive power of an H-bomb compared with a
more conventional fission design is from the fusion reaction.

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Element_
Ever since reading the original Popular Science article on this company it has
amazed me how little attention it has received in the media. It seems like
they are really on to something and their budget compared to other fusion
projects is tiny. I hope they receive continued funding.

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modeless
This sounds awesome; I wish there was more information available. I can't
quite visualize how the vortex would work. It needs to reach all the way to
the bottom of the chamber so the plasma can be injected through it, but it
also needs to be small in diameter at the center of the chamber so the
pressure wave can collapse it completely. Can those requirements be met
simultaneously? How fast would you need to spin the metal? Is it really
possible to make a stable vortex such that no liquid metal ever falls into the
lower plasma injector (which would presumably destroy it), even as you send
shockwaves through the chamber once every second?

~~~
Element_
You are over thinking it...the outlet port to circulate/drain the molten metal
would be the same hole the lower plasma injector uses. By using a curved
surface it can take advantage of the centrifugal force and surface tension of
the liquid metal to prevent the metal from falling down lower into the
injector. So basically there is a doughnut shaped orifice around the top of
the lower plasma injector that's connected to a pipe which feeds into the
liquid metal circulation system. Here is a cutaway drawing where you can see
it:
[http://1.bp.blogspot.com/_VyTCyizqrHs/ScF7J2w-TOI/AAAAAAAADL...](http://1.bp.blogspot.com/_VyTCyizqrHs/ScF7J2w-TOI/AAAAAAAADL8/1J2ryeF54Q8/s1600/gf0.jpg)

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HCIdivision17
Every picture in the article is just awesome. It's a dream lab: giant
industrial machines mixed with lab tech and whatever-it-takes-to-work.

Every bit looks to have a story. On the image of the sensor there's a sharpie
note "<\-- STUD" pointing to where a stud was taken off (I assume). Or the
aluminum foil wrapped around a pipe in the last image. This is what GTD
engineering looks like; it can be polished later.

The entire setup just looks _fun_ , like how I always imagined early rocket
labs must have looked like. Serious, but utterly interesting and ever
changing, tweaking, and upgrading.

Also the article is good. (But the eye candy made my day.)

