General Fusion in the news

[crowberry]

General Fusion is updating their webpages. There are additional papers that can be downloaded directly from their home page at http://www.generalfusion.com/blog/categ ... ic-papers/ like this paper:

Status of Progress Towards Acoustic Magnetized Target Fusion at General Fusion
Scientific Papers 9 Jun 2013

Abstract
Magnetized Target Fusion (MTF) is a hybrid approach to fusion in which a self-organized plasma is compressed with the inertia of a conductive liner to conditions that fulfill the Lawson criterion [1]. This paper provides an overview of MTF and the ongoing research at General Fusion (GF) to design, test, and demonstrate the ability to produce energy using its acoustic MTF technology.

Richardson, D., Froese, A., Suponitsky, V., Reynolds, M., Plant, D. “Status of Progress Towards Acoustic Magnetized Target Fusion at General Fusion” Published in Proceedings of the 34th Annual Conference of the Canadian Nuclear Society, 20

http://www.generalfusion.com/blog/wp-co ... S-2013.pdf

The other available papers in addition to the old 2007 and 2008 papers are:

Richtmyer–Meshkov instability of a liquid–gas interface driven by a cylindrical imploding pressure wave
Scientific Papers 20 Jan 2014

Progress Towards Acoustic Magnetized Target Fusion
Scientific Papers 10 Jun 2012

Developing Acoustic Magnetized Target Fusion
Scientific Papers 5 Jun 2011

[crowberry]

It turned out that this paper is still behind a paywall unless you have access to a library:

Richtmyer–Meshkov instability of a liquid–gas interface driven by a cylindrical imploding pressure wave
Scientific Papers 20 Jan 2014

Anyway three additional General Fusion papers is nice, even if the papers are from previous years.

[mvanwink5]

Crowberry,
Thank you alerting us to GF's website update. Recently the new CEO mentioned their target of putting in place full scale prototype funding by 2014's end and the mention of possibly 300 pistons vs previous vision of 200 pistons. GF's schedule is aggressive on all fronts, scientific, testing, simulation and finally financially. Apart from Tri-Alpha I see no dark horse team that has a complete team that compares to GF's. It is also worth emphasizing that development snapshots are well over a year old and in this fast moving development picture (speed of which in itself is amazing) needs to be recognized and digested properly.

My wild guess is the issue is more nailing down engineering details for the financial plan rather than "if" they have the working pieces (such as how many pistons and where to place them). Engineering in itself is not trivial and that has to be there before a supplier list gets winnowed down, bids solicited, results reviewed, and decisions made. Practicality, real world meets science team. An amazing symphony to watch using the scraps of information we get.

[swamijake]

There is still a big question on if this will work. From my read and rumours in the neighbourhood, there are still some major challenges, namely, keeping the plasma clean in the injectors, keeping the plasmoids alive long enough to get to the center of the reactor, and then what happens regarding plasma contamination during an implosion.

Yes they are getting fully prepared for success, but the science isn't finished. Keep in mind that Canada, and BC in particular, has some great tax benefits that go along with doing this type of research. The risk to the investors is relatively low as they have likely already recouped 60-70% of their investment through tax benefits.

[mvanwink5]

Yes, until the full size prototype is built and results show success, the bird is still in the bushes.

[prestonbarrows]

Polywell probably can argue that it's a good neutron source, but how much better than other neutron sources is it?

The only published numbers that I am aware of regarding Polywell neutron output are ~2*10^5 n/pulse at ~10^9 n/s. These numbers are from an info-dump by Bussard before his death and not strongly peer reviewed; questionable at best.

Taking these as a starting point, Polywell is basically useless as a commercial neutron generator. Commercial off the shelf units are available in the ballpark of 10^10 n/s at continuous duty. More specialized and expensive units are available into the 10^11 - 10^12 n/s continuous as custom jobs. This is about the limit for non-national-lab, non-fission-reactor, neutron sources; beam transport in the accelerator becomes too difficult/expensive.

That said, the Polywell should have much more headroom to scale up in theory. There is no experimental data available for how neutron output would actually scale with device size in the real world. Even being conservative and just scaling with core volume, a device the scale of existing commercial neutron generators (on the order of meters) would put you into the same ballpark or above. Being restricted to a pulsed reactor can also be an advantage for certain applications.

If it could indeed scale into a feasible net-gain type device, the neutron output would blow all of the existing technologies out of the water. That is an enormous "if" though. One could also claim that a tokamak like ITER will blow away any other existing system in terms of neutron output; this does not mean it is a reasonable solution for a neutron source.

The real questions are:
1) Reproducing fusion reactions at all in a Polywell geometry in a proper peer-reviewed experiment. Bonus if down at continuous duty or at least long pulsed.
2) Getting at least some idea of how output scales with size, b-field, electron energy etc.

[D Tibbets]

Polywell probably can argue that it's a good neutron source, but how much better than other neutron sources is it?

The only published numbers that I am aware of regarding Polywell neutron output are ~2*19^5 n/pulse at ~10^9 n/s. These numbers are from an info-dump by Bussard before his death and not strongly peer reviewed; questionable at best.
...

Considering a Polywell as a neutron source is limited in applicability at best. The Polywell is a highly modified fusor and this has been developed as a neutron source by Dalmer - Benze, though they didn't quite commercialize it. I suppose they decided it couldn't compete with current neutron sources.

I don't know where your numbers come from. What is 2*19^5 n/ pulse?
WB 6 results were reported as 500 *10^6 (500 million) neutrons per second isotropic output equivalent. This was based of a statistically uncertain count of ~ 3 neutrons/ test detected. With the counter calibration, stand off distance and claimed significant test duration of ~ 0.25 milliseconds the expected output of 500 million neutrons per second was calculated. This was an admittedly brief test duration, though Bussard's claim that this was several orders of magnitude longer test time than the physics involved- thus giving a picture of steady state operation.

Peer review of WB6 results are questionable at best. WB7 and WB8 is a different story. Plenty of peer review by respected physicists, just no open publication of the results for us to chew upon. Earlier EMC2 work was under review by a purported Navy review panel, though WB6 results obtained at the end of the contractual program probably was not scrutinized by the Navy overseers.

Speaking of output scaling by size is of modest importance at best. It is the B scaling that is the key. And the real questions concern the input complexities and scaling, not the output.

Dan Tibbets

[prestonbarrows]

Sorry typo, edited to fix. Those numbers are from "The advent of clean nuclear fusion - superperformance space power and propulsion".

My point is that top of the line, commercial, continuous duty, electric neutron generators today are on the order of 1E9 to 1E12 n/s DD or DT. This is only on the order of 0.0001-1.0 Watts of fusion power released.

For a polywell reactor to ever be a reasonable power source in the future, it would need to produce on the order of 1E3 to 1E6 Watts. If it could ever be demonstrated to come close to that without ballooning in size and complexity like a tokamak, such a device could make an excellent neutron source even if break-even is never achieved.

If one could scale output with B-field, so much the better. Higher power density and higher neutron flux is always good for a neutron generator. Again, scaling with volume is a much more conservative assumption; I do not believe there is any published experimental data on B-field scaling at fusion-relavent conditions. If anyone has any, I would love to see; The best examples are Park's demonstration of high beta transition and Carr's thesis on well depth scaling at very low energy. All the scaling laws people cite are based off first principles on paper with gross assumptions. Look to the history of essentially any fusion project in history and those simple assumptions on scaling never turn out as good as you would expect.

The original poster was asking for context in regards to polywell's neutron output in terms of existing neutron generators.

tl;dr: a small, Q<1, polywell has the possibility to make an excellent neutron source assuming it actually works.

[D Tibbets]

As a neutron source, the Polywell is a poor choice. General fusion is also a poor choice probably. If I had to chose a horse in the race purely for a useful powerful neutron source of modest size- perhaps even small enough to fit in a drill bore hole (though still far short of breakeven) I would go with the Dense Plasma Focus. For large scale neutron production as part of a working power plant (>1 Q). The Polywell, FRC, General Fusion all have potential. As you say though, all of this is predicated on the system actually working as hoped.

I do doubt the Polywell will reach Q>1 at outputs much less than 100 MW (unless you invoke highly optimistic evolved capabilities). The DPF and FRC may reach Qs greater than one at a few MW. The problem with these is that the optimistic Q performance peaks at a few MW. Polywell, in theory at least, can scale up to almost any output. The economics of many small reactors versus a few larger reactors(like Polywells) versus a single huge reactor (Tokamak) is interesting. If the fusion reactor works but cannot compete with continuing advances in wind and solar along with other renewables the usefulness is questionable. Except for medical isotopes and weapons research, a big fusion reactor or marginally profitable small fusion reactor may be a niche product. I don't know where General Fusion would fit in this picture.

WB 8, whether it reached Beta= 1 or not, should have shown shown scaling over a range of B fields (~1-8 thousand Gauss) relative to WB6/WB7 baselines. If they did not generate this data, they were neglecting the whole primary advertized purposes of that stage of research. The major fly in the ointment seems (from my outsider perspective) the challenge of getting electrons into the machine, not containing them once internalized- or perhaps more significantly, doing both at the same time.

Dan Tibbets

[crowberry]

General Fusion has published a new promotional video on Youtube at http://www.youtube.com/watch?v=n8qgAgyqdBM.It is 3 min 31 s long. There is a new rendering of their piston driven reactor.

[mvanwink5]

Youtube video is slick. The video is ground work to get cash, lots of cash. PR work gets GF in a better negotiating position when talking to VC's. Money from Uncle Sam is fickle, slow, and the strings attached put the needed bridge to be built in the desert where there is no river (in other words politics yields absurdity). VC money is the way to go because these guys want the project to succeed, fast, it is the only way to get their money back (about tax credits, tax credits are like getting the cute dress for sale at a great discount, "discount" doesn't make money, it reduces money spent).

So, this is the work of their new CEO, Nathan Gilliland, to get the Big money, or at least that is my thinking.

[Skipjack]

Youtube video is slick. The video is ground work to get cash, lots of cash. PR work gets GF in a better negotiating position when talking to VC's. Money from Uncle Sam is fickle, slow, and the strings attached put the needed bridge to be built in the desert where there is no river (in other words politics yields absurdity). VC money is the way to go because these guys want the project to succeed, fast, it is the only way to get their money back (about tax credits, tax credits are like getting the cute dress for sale at a great discount, "discount" doesn't make money, it reduces money spent).

So, this is the work of their new CEO, Nathan Gilliland, to get the Big money, or at least that is my thinking.

I don't think GF ever got money from Uncle Sam. They are a Canadian company.

[mvanwink5]

Yes, Unka Samm has not put any money in the kitty, but politics is the same the world over.

[crowberry]

The video is probably in preparation for the next round of investments needed to build the pilot plant reactor.

[GIThruster]

Youtube video is slick. The video is ground work to get cash, lots of cash. PR work gets GF in a better negotiating position when talking to VC's. Money from Uncle Sam is fickle, slow, and the strings attached put the needed bridge to be built in the desert where there is no river (in other words politics yields absurdity). VC money is the way to go because these guys want the project to succeed, fast, it is the only way to get their money back (about tax credits, tax credits are like getting the cute dress for sale at a great discount, "discount" doesn't make money, it reduces money spent).

So, this is the work of their new CEO, Nathan Gilliland, to get the Big money, or at least that is my thinking.

VC money also has the outcome that the investor takes over ownership of the lion's share of the IP value and stocks. It's not the simple thing you think. there are almost no projects that VC's involve themselves in, where they take anything less than a huge portion of the cash value of the company and its properties, including all IP's, trade secrets, licenses sold in the future, etc. personally I think though it's a huge hassle, the way to go is grants when possible. But of course, GF doesn't have access to US grant funds.