Saturday, January 07, 2012

Capacity Focus, 30: The Polywell -- polyhedral potential well -- fusion reactor initiative

The Wb-6 Polywell lab scale reactor
Over the past twenty or so years, Robert Bussard and his successors have championed a polyhedral electrostatic potential well fusion reactor, that if successful would be orders of magnitude more compact and less expensive than the Tokamak toroidal design that has been dominant in fusion research in recent years.

The basic concept of the polywell reactor is that if a space charge cloud of electrons can be trapped in a magnetic zone, then it creates a virtual cathode that will draw down injected light atoms into the potential well; in effect substituting a much smaller electrostatic field well for the sort of massive gravity-based well that forms stars, the natural fusion reactors that provide energy to the universe. These may then fuse, releasing energy. 

That energy is then potentially harvested in various ways, depending on application and the particular nuclear reactions triggered based on what atoms have been injected. Fusion, of course, generally gives rise to much shorter lifespan radioactivity so wastes will be much more manageable than with fission of heavy elements, the conventional nuclear technology of today.

Both fission and fusion rely on the Einstein relationship between mass and energy, E = M*c^2 :

The source of nuclear energy

The suggested big advantage of a polywell reactor, is that this would be a much more compact -- thus potentially modular -- design than the Tokamak doughnut reactor that has dominated fusion research in recent years.

Bussard's Google Talk, given in 2006, gives a useful overview of not only the possibilities, but also the challenges to move forward a minority initiative in an era of science driven by big government and institutional dominance:

In the talk, Bussard highlights how in effect water would be the fuel of the future (along with Boron etc), how a polywell plant could be used to drive a sugar cane to fuel process, and desalination that would enable agriculture in the desert regions of the world. Such would transform the global economy in many ways, opening up many tropical and semi-tropical regions as energy powerhouses for the global economy, getting the world out of oil addiction -- and oil wars -- and transforming deserts into productive land.

In addition, he points out that a rocket based on the fusion reactor would reach Titan, the moon of Saturn, in 74 days; i.e. this technology -- if successful -- would open up solar system colonialisation. 

A summary of the Google talk (which may have a few mistakes in it) is here, and a paper by Bussard towards space flight is here. At an Ars Technica discussion, commenter AndersDK summed up the basic challenge faced by this and many other alternative energy and development projects:
. . . The problem with this kind of tech is that while the possible payoff is HUUUUGE, the research is expensive, there is NO guarantee for success AT ALL and even if it works there is a lot of infrastructure out there that has to ad[a]pt to it. How many people would dump $100-200 mill in tech with an unclear chance (could be 1%, could be 50%) of payoff of BILLION and BILLIONS. If you had a lot of smaller but equal risky programs you would rather choose those to diversify your risk.
To this, commenter slowtech replied:

True, but how many people would be willing to invest $100-$200? maybe not a million, but enough to lower that total figure a little.
This is the precise problem that ever so many high potential payoff but unproven initial investigatory projects face: they are expensive, they run into bureaucratic red tape tangles in existing institutions, and it is hard to draw enough public attention and interest to get a large cluster of small injections that add up. So, they limp along, half-starved and carried by self-sacrificing visionaries.

The web is one step towards the solution, as something that draws a swarm of attention can start on a shoestring then snowball if it can "go viral." For that, you need some sort of attention-getting event, presentation or incident that triggers a critical mass of wider attention and interest. (I cannot but think that the AA CCS initiative needs this sort of push, in addition to a demonstration course done in part as a proof of concept and in part as a publicity event . . .  [candidate courses: here, here, here, here].)

Which is why a newsworthy incident, a videotaped public presentation sponsored by a significant organisation or the like are all so helpful. In this case, we had a Google Talk event that led to a web buzz, and some onward funding to do a WB-7 has been secured.

Of course, all of the ideas being discussed are visionary and high-risk/high potential payoff, but they open up another way to look at the world and its possibilities,  especially sustainable energy and sustainable development. 

In that context, we need to reflect on this technology in parallel with Marcin (pronounced: "march-in") Jakubowski's Open Source Ecology and Global Village Construction Set ideas and the like; which recently got a publicity boost through a 5 or so minute TED talk. (Ironically, Jakubowski is a Fusion Physics PhD who concluded that his fusion physics background had no relevance . . . )

A briefer video that shows what a commercial polywell reactor might look like, to scale, is here:

Monitoring developments and opening minds to possible alternatives, so we can re-think development and sustainability out of the box . . . END


Dave said...

There's actually a board devoted to the concept.

GEM of The Kairos Initiative said...

Thanks ever so much. Quite a forum!

GEM of The Kairos Initiative said...

Dave, please do something about your technical FAQ page. First link says, moved. Next page came up, threat detected by my antivirus. A pity.