The Promise of Controlled Nuclear Fusion Part XVI

In the last report, I warned, in the context of the upcoming Melbourne Cup, that horse racing can turn up some remarkably unexpected wins from outsiders. In the event, a week later, the race was won by a 50:1 outsider, ridden by a female jockey! I’m not sure which part of that was the greater shock to the still very chauvinist Australian racing fraternity but my original point was that the controlled nuclear fusion race is at least as uncertain as horse racing. Of course, that race to abundant, clean energy generation is not confined to LENR but includes hot fusion as well and it is this “bigger brother” in the fusion stakes that I want to concentrate on this time.

Last time, I did touch briefly on hot fusion by noting the November 2nd Time Magazine article entitled “A Star is Born” by Lev Grossman. His excellently written article should be regarded as a “must read”. It is not freely available on-line or in print, but is well worth the price.

The article is mostly about one particular enterprise, Tri Alpha, and its co-founder and champion, Michl Binderbauer. It is one of several recent startups in the hot fusion field which I shall return to later but I think it is instructive to look further back in time (if not in Time!).

As I noted in part one in this series, the very first efforts in controlled hot fusion started well over half a century ago and, as a schoolboy in 1958, I remember the fanfare when the British made ZETA first seemed to have achieved it. Later, a very embarrassing retraction had to be made. There is a Wikipedia article on the Zeta, also a “must read”, which is instructive from a number of viewpoints, including technical, historical, political and psychological.

ZETA, short for “Zero Energy Thermonuclear Assembly”, was a major experiment in the early history of fusion power research. It was the ultimate device in a series of UK designs using the Z-pinch confinement technique, and the first large-scale fusion machine to be built. It sought to exploit the strongly exothermic (energy releasing) nuclear reaction between deuterium and tritium, known as the D-T reaction. Because of this bonus energy at the outset, the D-T is still the reaction that many physicist turn to. In fact, JET, ITER and most of the other old and new plasma fusion devices are still based on it. However, as we noted in part one, this reaction requires Tritium, a rare and mildly radioactive gas and it produces huge numbers of neutrons, which, unless harmlessly captured will “activate” any surrounding metal to create radioactive isotopes, not all of which will quickly decay away.

But, back to 1958. Students of science history may find it difficult to appreciate just how big an event the Zeta was at the time. It seemed to represent an “Indian Summer” for British science versus the always better funded and seemingly endless “American Summer” of R&D on all fronts. British jingoists even hailed the Zeta as more important than the world’s first artificial satellite, Sputnik 1, launched by the USSR in October 1957. There was another, more ironic Cold War element in that a leading “British” fusion researcher was Klaus Fuchs who, as we know today, had already passed atomic bomb secrets to the USSR!

The Zeta failed for complicated reasons but chief among them was that it was basically a straight tube device and so the magnetic fields diverged at each end. This made the choice of a toroid shape as assumed by the Russian Tokamak (and that Jet and ITER are still based on) a seemingly obvious one but, as history shows, that “new” approach has yet to succeed half a century later!

But, although the Zeta shed light on a number of crucial issues which assisted future Tokamak and other devices, the acute embarrassment its overall failure caused still influences the PR around fusion to this day. In my opinion, it was the memory of that “red faced moment” of 1958 that surely influenced the “survivors” to be almost pathologically skeptical when Fleischmann and Pons took the stage in 1989, offering what was erroneously called “cold fusion” and quickly but unfairly dismissed.

Again, the Zeta miasma also resulted in the hot fusion effort reverting to a very slow but very sure, peer reviewed, paper-driven academic exercise which still characterizes the JET and ITER projects to this day. Only the advent of the new generation of startup corporations typified by Tri Alpha can perhaps restore the pre-Zeta spirit of rapid and exciting progress in hot fusion with any fear of failure rightly outweighed by the wider fear for the whole planet if there is very much more coal and oil burning in the future!

So let us now take our own look at these “new kids on the hot fusion block”. Surely the most bizarre would be the Canada-based General Fusion Reactor, which looks as if it has walked straight out of a Jules Verne novel! In it, fusion temperatures are achieved by 300 pneumatic rams providing extreme adiabatic compression upon an inner core of molten lead and lithium. In a 2008 article, it was dubbed “a thermonuclear diesel engine” which, IMHO, is not a bad marketing phrase, even if founder, Michel Laberge doesn’t seem to like it. At first thought, the design concepts seem to be too far out of left field but, the more you think about them, the better they seem to sound. Big money investors from inside and outside Canada obviously concur, having so far stumped up over 100 million dollars!

Another (nearly) new kid on the block is Lockheed Martin’s High Beta Fusion Reactor that we introduced a year ago, in part 10. So, strictly speaking, project leader Tom McGuire is already one “real-world” year into his then projected five year schedule for achieving a small fusion reactor prototype. The project already has its skeptics, curious for at least some interim results, if only broad estimates of temperature and confinement.

But the most exciting of the “new kids” is surely, as the Time article indicates, the Tri Alpha, conceived by the late Norman Rostoker and developed his protege  Michl Binderbauer. Like the General Fusion Reactor, it is the result of large servings of lateral thinking and paradigm shifts but is still within the broad confines of nuclear physics and particle accelerator technology in particular.

Noting that the Large Hadron Collider and its ancestors never had much trouble in keeping the particle orbits stable – the big problem with Tokamaks – they reasoned that twin particle accelerators could be placed to fire directly at each other. At the collision point, a chamber hosting six neutral beam injectors combines everything to produce a 10 million degree plasma, sized and shaped like a rugby ball with a hole through the center. In this configuration, as Binderbauer designed and calculated, it actually generates its own magnetic field that, in turn, confines it. As Grossman writes “It’s an elegant piece of plasma-physics bootstrappery”.

Crucially, the resultant plasma has been stable for as much as 5 milliseconds – a very long time in the hot fusion world so far and perhaps long enough to ultimately produce net energy. But Binderbauer’s ambitions go beyond this. As we mentioned above, the D-T reaction, for all its low threshold and energy efficiency will inevitably produce radiation by-products which may well destroy the whole “much cleaner than fission” image that hot fusion has always promised – at least at the PR level. Binderbauer ultimately wants to use a much cleaner nuclear reaction, the Proton-Boron (P-B) one, inside the Tri-Alpha. The catch is that it is both less energy efficient and requires a much higher temperature threshold to achieve. A more convenient measure of that plasma temperature is in terms of the energy the particles comprising it would typically have and this is usually given in terms of electron volts. The threshold for the P-B reaction is 600,000 electron volts or 600 Kev. However, in terms of particle accelerator energies, this is comparatively modest. Even Aura II, the now obsolete particle accelerator that I myself worked with at Auckland University (c. 1968), could produce deuteron beams with energies up to 7 million electron volts (7Mev)! However (as I recall), this energy beam was only present in tiny levels of current, in the order of micro-amps or millionths of amps. Very much higher beam currents would be required for fusion power production.

I must conclude this already “bumper edition” but, of course, there is much more to be examined about the history and current direction of hot fusion. A broad overview appears in Wikipedia here, although the article is almost completely dismissive of what it calls “cold fusion”, or LENR as we have come to call it.

But, surely, the point is that both hot fusion and LENR must now be treated with equally serious respect and urgency. They are both ultimately striving for the same goal. If we care to reflect on the twin threats of global warming and rising sea levels that are being accelerated by ongoing oil and coal burning, we should recognize this goal as nothing less dramatic than saving the world!

P W Power
November 2015

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