General Fusion in the news

[mvanwink5]

http://www.vancouversun.com/business/Tech+businesses+open+doors+attendees/9624549/story.html
Tech businesses open doors to TED attendees
Some hope to attract investors, others want to showcase innovative work

— and General Fusion, which is developing a small, commercially viable fusion reactor using proprietary technology.

So, a company getting ready to solve world's energy problem gets one sentence and 15 minutes of showtime at TED clapfest. Deep pockets and pea brains.

Does that meet the minimum criteria for a rant?

[hanelyp]

http://www.vancouversun.com/business/Tech+businesses+open+doors+attendees/9624549/story.html
Tech businesses open doors to TED attendees
Some hope to attract investors, others want to showcase innovative work

— and General Fusion, which is developing a small, commercially viable fusion reactor using proprietary technology.

So, a company getting ready to solve world's energy problem gets one sentence and 15 minutes of showtime at TED clapfest. Deep pockets and pea brains.

Does that meet the minimum criteria for a rant?

Eh, I can still see reason showing underneath the emotion.

[mvanwink5]

The Richtmeyer-Meshkov instability can be a problem too, see the FPA presentation on page 6 and the following two papers.
If there is too much lead contamination in the plasma then it will cool off. There are several things that GF can adjust to keep the problems under control like the acoustic pulse amplitude, duration, the angular velocity of the PbLi-fluid, possible injection of Li-nearest the center of the reactor to avoid Pb-contamination. Also the temperature and density of the plasma before the acoustic compression are important parameters. To have an idea of the good parameter set realistic simulations are needed. Currently the GF simulations are simplified and are missing important aspects of the acoustic vortex compression.

First, thanks for the papers and links. It would have been nice to get the full articles, but the abstracts were almost enough especially with the first RM paper filling in a lot of details. I did not understand the RM slide on page 6 of the December release of the September 25, 2013 FPA presentation until looking through the RM instability modeling paper. So, the plasma compression problem is twofold, spheromak compression stability, first, and second, the acoustic compression lead - plasma chaotic interface. Also, Pb contamination from the RM instability was completely off my radar. Having knobs to turn to compensate for these issues makes for a photo finish, or build it and see situation. The VC's will earn their money on this project. Again, thanks for those papers.

Ok, I am dropping my Trifecta bet a bit for GF.

[crowberry]

I think it is sensible for GF to retain a conservative approach until they have shown scientifically net gain.So when Michel Laberge quotes the chances of success as 50-50 it really means that there is a real significant risk that their concept will not work. Results from their net gain demonstration experiment (AKA "Large Scale Plasma Compression") will be very interesting to hear about once they have progress in that area.

I happened to find a very good paper (behind a paywall) from last year on the overall progress of GF. The content is basically the same as in their presentations, but it gives a clearer overview and is much more readable and understandable than their slides.
Acoustically driven Magnetized Target Fusion, http://dx.doi.org/10.1109/SOFE.2013.6635495

[mvanwink5]

GF had begun large scale compression tests before their Kobe, Japan September 25, 2013 presentation. In the December 2013 release of the September 25, 2013 slides (the updated release had fewer slides and left these large scale test pictures out - 30 pages vs 49 pages), GF showed pictures of the 42 cm diameter, 10.5 mm thick liner, 60 MJ driver and test pictures, no data, so it looks like a non instrumented preliminary test just to visually check compressive explosion for uniformity and time the wall collapse. Frost was on the ground for the test (in the mountains?) and the hefty concrete blocks for containing the blast got knocked around. So, GF seemed to start their large tests by October of 2013.

It is now middle of March, so would not be surprised if they have had positive progress on their large compression test program, and bringing Nathan Gilliland on board as CEO looks like a move to go for a round of big financing, which would also put weight behind positive results for their large scale compression tests. On the other hand, it may be that he was brought on board early enough so he can get up to speed in anticipation of future positive results, and do some glad handing with TED attracted VC's.

Still, my take on the 50-50 comment was that simulations of such a complex event (it is all simulation until the net system is built, even with full scale subsystem tests), numerical computer simulation of acoustic compression of plasma by 200 pistons in a 3 meter diameter sphere, can only be trusted so far. Therefore, I take that seemingly grudging odds comment as really encouraging that their full scale subsystems test results are indeed positive and ready for building a net test device (planned for 2018?). The TED event then must be perfect timing in that regard, and Nathan Gilliland value is he knows the special VC hand shake; how much will an accountant be able to come up to speed in the end, anyway.

I think they are going for financing the net machine at TED.

Best regards

[mvanwink5]

An article written from a visit to GF (facility tours seemed to have been arranged coincidental with the TED conference.)

http://recode.net/2014/03/18/the-future-may-be-getting-close-to-reality-in-vancouver-with-d-wave-and-general-fusion/
The Future May Be Getting Close to Reality in Vancouver, With D-Wave and General Fusion
March 18, 2014, 2:11 PM PDT

Meanwhile, a 15-minute drive away, General Fusion, which shares investors with D-Wave, is about two to three years out from creating its own power plant. Today, the pistons work well, and the plasma is hot enough and dense enough. Within the last month, the gas donut has started lasting long enough for the system to work, so now the company is turning its focus to compression and timing, according to Michael Delage, VP of strategy and corporate development.

Similar to D-Wave, General Fusion is at a point where it needs to get its system working and cost effective. “We expect to be at break-even energy in a couple of years,” said CEO Nathan Gilliland.
When this is built out, General Fusion thinks it can provide power at a cost of seven cents per kilowatt, comparable to the cost of coal.
Why this is important? As Laberge said, “It could solve all our energy problems cleanly for the next billion years.”

So, smooth acoustic compression in the liquid lead reactor is the last hurdle after all (dealing with RM liquid lead - plasma interface instability), and stable spheromak plasma compression itself is solved.

[crowberry]

It's nice to hear that there is good progress at General Fusion. They also published their electricity production cost estimate:

When this is built out, General Fusion thinks it can provide power at a cost of seven cents per kilowatt, comparable to the cost of coal.

That should be kWh of course. Being competitive in price with coal will be very important if fusion energy is going to be deployed on a large scale. The simpler and the cheaper the fusion device is the better this goal can be achieved.

[mvanwink5]

crowberry,
7 cents/kwh I suspect is the total system cost - turbine, generator, station service (auxiliaries), but maintenance and operation costs are just as important, so in my view I always put doubt in numbers without seeing what assumptions are made, and it is rare that the assumptions are stated. I suspect GF is being conservative, but have no real idea.

possible injection of Li-nearest the center of the reactor to avoid Pb-contamination

Any idea how GF could use lithium in this way? How does one go about injecting, using a jet of lithium aimed at the center of the sphere?

GF has been working on the multiple issues in parallel, and have had over 1.5 years (first vortex collapse July 2012) to look into this and work towards solutions using the 1 meter diameter reactor to compare results with their simulation code. Further, GF only had one slide on the RM stability, so I wonder how concerned they are with this issue at this point? Perhaps there was no rush on solving the RM stability issue as based on their focus GF seemed to see stable spheromak compression as their chief obstacle, and they perhaps were surprised to have made such progress with plasma compression. At any rate I have no way to surmise how tough GF views this RM issue, but I am surprised that it seems to be the last issue to be resolved (for this project stage).

[hanelyp]

Lithium in the plasma is less problematic than lead, but how does vapor pressure compare for a liquid lithium vs. lead first wall?

[crowberry]

crowberry,
7 cents/kwh I suspect is the total system cost - turbine, generator, station service (auxiliaries), but maintenance and operation costs are just as important, so in my view I always put doubt in numbers without seeing what assumptions are made, and it is rare that the assumptions are stated. I suspect GF is being conservative, but have no real idea.

possible injection of Li-nearest the center of the reactor to avoid Pb-contamination

Any idea how GF could use lithium in this way? How does one go about injecting, using a jet of lithium aimed at the center of the sphere?

GF has been working on the multiple issues in parallel, and have had over 1.5 years (first vortex collapse July 2012) to look into this and work towards solutions using the 1 meter diameter reactor to compare results with their simulation code. Further, GF only had one slide on the RM stability, so I wonder how concerned they are with this issue at this point? Perhaps there was no rush on solving the RM stability issue as based on their focus GF seemed to see stable spheromak compression as their chief obstacle, and they perhaps were surprised to have made such progress with plasma compression. At any rate I have no way to surmise how tough GF views this RM issue, but I am surprised that it seems to be the last issue to be resolved (for this project stage).

As the PbLi-liquid is spinning very fast it will mix very well so I don't really know how to do it. I guess this would be a last resort option and it would need studies and simulations on how to do it in practice.

General Fusion has surely known from that start that the Richtmeyer-Meshkov instability can be a potential show stopper.
Their paper from June 2013, "Acoustically Driven Magnetized Target Fusion",http://dx.doi.org/10.1109/SOFE.2013.6635495
contains this text that I quote:

A smaller-scale aspect of the wave-surface interaction dynamics is the onset of the Richtmyer-Meshkov (RM) instability, which in the worst possible case would completely undermine the ability of liner to cleanly compress the CT plasma.

The problem has not really previously been studied in the spherical geometry used by GF, so they need to continue with the simulations and check them against the data from the 1 m "Mini-Sphere". A practical complication mentioned in the paper is that the pressure distribution they have so far achieved in the "Mini-Sphere" is of the wrong shape, which can actually enhance rather than damp the RM-instability. The relative timing between the different pistons allows GF to shape the geometry of the pressure pulse, but this is not so easy to do with the 14 piston "Mini-Sphere" as with a full scale 200 piston system. But in order to design the 200 piston system, they need to better understand what level of initial disturbances are tolerable in the vortex surface. So there is much work remaining before this issue can be settled.

[quixote]

As the PbLi-liquid is spinning very fast it will mix very well

Wouldn't the high centripetal acceleration tend to separate the Pb and Li rather than mix them based on the sedimentation principle? That is, wouldn't it act like a centrifuge, separating the elements?

[quixote]

As the PbLi-liquid is spinning very fast it will mix very well

Wouldn't the high centripetal acceleration tend to separate the Pb and Li rather than mix them based on the sedimentation principle? That is, wouldn't it act like a centrifuge, separating the elements rather than mixing them?

[hanelyp]

As the PbLi-liquid is spinning very fast it will mix very well

Wouldn't the high centripetal acceleration tend to separate the Pb and Li rather than mix them based on the sedimentation principle? That is, wouldn't it act like a centrifuge, separating the elements rather than mixing them?

If the liquid metals don't dissolve together and turbulence is kept low (as I expect it must be for the General Fusion implosion to work right) the metals should separate into layers by density.

One point I'm not seeing is how you get an other than paraboloid core in the spinning liquid metal. Or does General Fusion intend a mostly 2D driven implosion?

[mvanwink5]

Next Big Future has a GF update, but we have seen it earlier here. http://nextbigfuture.com/2014/03/general-fusion-making-progress-to-full.html#disqus_thread

In the comments Soylent posted a link to the full pdf of a research article we only had the abstract of with full article behind a paywall. Here is that link:
http://arxiv-web3.library.cornell.edu/pdf/1310.6010v2.pdf

[DeltaV]

One point I'm not seeing is how you get an other than paraboloid core in the spinning liquid metal. Or does General Fusion intend a mostly 2D driven implosion?

Wild guess here, but in line with the geometry of conic sections and their associated surfaces of revolution:

Slicing a two-nappe regular cone with a plane of varying tilt, relative to the cone's axis, gives (starting with 90 deg to axis) a circle, a family of ellipses, a parabola (ellipse with one "focus at infinity"), then a family of hyperbolas. Point being that there is a continuous progression of curves. Similarly for the surfaces.

Since the container is a closed hollow sphere instead of an open-ended cylinder, above some critical angular speed the equilibrium surface approximates a prolate ellipsoid having both foci inside the sphere. As speed goes up, the upper focus moves from vertical infinity to inside the sphere.

Spinning faster approximates a sphere (foci coincide). Even faster, an oblate ellipsoid (coincident foci become a single horizontal circle).