Fusion for the Future: ITER

The way of the future is fusion. I dream of a world where humans have harnessed the power of the Sun. Clean, safe, energy. But there is no clear path to fusion. The most exciting possibility for a future with fusion may be the International Thermonuclear Experimental Reactor or ITER. ITER is not the only option of course. Previously, I have discussed the National Ignition Facility or NIF which has pioneered unique technologies is the field, but their success is not ensured. Many small research projects around the world are also struggling to realize the dream of fusion, but with budget shortfalls and increasing pressure to produce results we as a society may shortsightedly end the dreams of a fusion future.

Fusion is what powers the Sun and all stars in our Universe. Fusion is the joining of two or more separate atomic nuclei into a larger nuclei. Fusion can create energy because the mass of the input and output nuclei are not necessarily equal in mass. An overview of what fusion is and why it is so important can be seen on my previous post on Fusion for the Future. Many scientists in the field acknowledge that a rapid development of fusion is unlikely, much less a commercial development, but there is hope. A reasonable time frame may be half a century before we see a world powered by the same process which drives the Sun. It will be an almost entirely clean, limitless, reliable, and safe source of power.

Christopher Llewellyn Smith states some cold hard numbers that are worth mentioning again. The price of ITER is at least 13 billion Euros or $17 billion. This cost is justified and dwarfed by the magnitude of the energy usage on Earth which amounts to a $5 trillion dollar a year market (I checked some of these numbers and they seem approximately correct. Did you know that you can download the International Energy Agency's annual reports as an iPhone or iPad app?). Particularly shocking are the subsides to fossil fuels which are over $500 billion a year worldwide (I am not so sure about this number, but the United States alone subsides fossil fules to the tune of $10 billion a year) while the subsides to renewables are only $45 billion worldwide. Smith says that the renewable energy sources of wind, bio, geothermal, and marine will never be able to meet the world's energy needs a current consumption rates. We must use solar, fission, or fusion energy.

It is a curious thing to ask a scientist to speculate on the future, but these two scientists have indulged us with a time frame for achieving fusion. Maybe the middle of this century at best they say. What makes fusion so difficult?

The key to releasing the energy of the Sun is forcing the nuclei of atoms close enough together for them to overcome their electrical repulsion and allow the strong force which binds nuclei to merge the nuclei together. Such favorable conditions for atoms to smash into each other can only occur under extreme temperatures and pressures, like say at the center of a star, but it is almost impossible to hold a star on earth. Anything which is hot enough to undergo fusion is also hot enough to burn through any container, thus we must contain something without quite touching it. Enter the magnetic doughnut known as the tokamak. A tokamak is a toroidal or doughnut shaped container that uses magnetic fields to confine plasma. Plasma is a state of matter where all the atoms are ionized (the electrons that normally orbit the protons in the nucleus have escaped)—and at these temperatures the atoms contained in the tokamak are definitely ionized. Magnetic fields apply a force on the charged particles of plasma such that the plasma can be corralled and kept away from the walls of the container. In an actual tokamak huge magnets encircle the enclosure as shown in the figure here where the magnetic coils and the ITER plasma surface is shown. The colors and contour lines indicate the magnetic field strength which is not quite perfect, the lines are wavy, due to deviations from perfect symmetry in the structure because the tordioal magnetic field is made of a finite number of magnetic coils. The ITER tokamak will be huge. Check out the tiny little person (bottom left) in the image below.

The complexity of this machine is astounding. One key challenge that must be overcome is the confinement of the plasma in a controlled manner. The Confinement Topical Group will determine exactly how to accomplish the confinement and avoid the performance degrading effects of Edge Localized Modes or (ELM modes). The hotter the plasma is the more internal plasma pressure is that must be balanced by stronger magnetic pressure fields; we could view this system in analogy to a balloon where that the plasma is the air under pressure and balloon's walls are the magnetic fields. The exact ratio of the plasma's internal current, the physical size of the tokamak, and the torodial magnetic field is a carefully tuned parameter to balance the gas temperature and magnetic pressures which does not yet have a known optimal configuration (the goal is I/aB < 2.5 where I is the plasma current, a is the minor radius, and B is the toroidal field on axis). It has been observed that the ELM modes periodically become unstable and have breakouts. This creates a large energy flux in a short time, like that of a solar flare on the Sun, where hot plasma breaks free of the magnetic fields. When this occurs the plasma may touch the side walls of the tokamak and overheat the internal surfaces to many thousands of degrees. The side wall surfaces will be evaporated and eroded inside the plasma chamber. In this way the ELM modes result in the introduction of plasma impurities which contribute to raising the effective atomic number (the number of free protons per particle) of the plasma which results in greatly reduced fusion efficiency or even the halting of the fusion reaction entirely; the target is to keep the effective atomic number below two. The aggregate erosion is large and the lining of the tokamak walls may  need be replaced often. In order to operate the machine continuously and cost effectively the ELM modes must be controlled. The control of ELM is paramount for a successful fusion tokamak. In the video below Alberto Loarte tells us a little more about the control of ELM modes and clever ways that the ELMs are dealt with.

The plasma instabilities inside a fusion reactor are a serious engineering challenge, but they are not a safety concern at all. Unlike a fission reactor, when a fusion reactor is compromised it does not go critical in a dangerous explosion (like a fission reactor would), instead it just fizzles out harmlessly. This technology is not perfect though because while some may claim that a fusion reactor would create no dangerous radioactive material in fact it would produce some radioactive material that would need to be handled. It is the walls of the reactor which will become slightly radioactive (through neutron activation). Conveniently though the half life of such radioactive waste materials is less than 100 years and could be entirely handled on site.

We should all be hoping for fusion. I spoke with Michel Claessens, the head of communications for ITER,  and one of the questions I asked him was, what should the public know about fusion and ITER?

As much as possible. More seriously, I would be happy if people understood the differences between fission and fusion.

And he has a point I think. Most people simply don't understand what is at stake and what our options our. If you are reading this then you are already more informed than most. Tell people about the difference between fusion and fission and encourage your government (no matter what country you live in) to follow a wise energy policy. While I was writing this article the United States changed its funding proposition for ITER which was a welcome change because at one point the United States looked like it would falter on its commitment to fusion research and ITER completely. This is an investment in our future and the Earth. I asked Claessens a question about this topic too, how important is worldwide collaboration in achieving a successful ITER project?

Worldwide collaboration is useful and even necessary - to pool and ensure the best use of resources (human and financial). The ITER project is so complex that no single country has the scientific and technological skills to build the machine alone. In addition, the international collaboration was seen by ITER fathers (Gorbachev and Reagan) as a way out to cold war.

The idea of harnessing the power of the Sun on the Earth is so much more than just a scientific endeavor. It is a very human dream to hold the Sun (what culture does not have some kind of original creation story or explanation for the sun?) and it is possible that realizing this dream may bring us together for all of the right reasons.

The Last Question

The last question was asked for the first time, half in jest, on May 21, 2061, at a time when humanity first stepped into the light. The question came about as a result of a five dollar bet over highballs, and it happened this way:

Alexander Adell and Bertram Lupov were two of the faithful attendants of Multivac. As well as any human beings could, they knew what lay behind the cold, clicking, flashing face -- miles and miles of face -- of that giant computer. They had at least a vague notion of the general plan of relays and circuits that had long since grown past the point where any single human could possibly have a firm grasp of the whole.

Continue reading The Last Question by Isaac Asimov or hear it spoken below.

It is interesting to note that different versions of this story I have encountered state the the sun will burn for ten billion years or 20 billion years. The written story above says twenty while the spoken story says ten. I don't know what the original version said (does anyone out there?). Perhaps this reflects our changing understanding of our sun which suggests that ten billion years is more appropriate.

Imagine the next 60 years

Futurism is an endeavor fraught with speculation. This is an inescapable fact. Many people, myself included, like to think about the future and wild things like space travel or exotic space ships, but this thinking is too often aimed at tangible objects and fiction. What we need is a frame work for thinking about the future that involves the most important factor and that is people. Consider the future in terms of the human development index versus planetary health. Consider how the future might be and what we want the future to be like. This is a refreshing approach to futurism because rather than an obsession with a singular aspect of the future, like the singularity, we are encouraged to make a plan for what to do with the wild technologies we may or may not obtain. Here is Dr. Chris Luebkeman with four predictions for Earth's future.

Spirit, Already Dead

On January 26th, 2274 Mars days into the mission, NASA declared Spirit a 'stationary research station', expected to stay operational for several more months until the dust buildup on its solar panels forces a final shutdown.

If the Spirit rover is just a little robot crawling around on a little red planet somewhere, then why are we so sad that it is dying? The rover is certainly easy to anthropomorphize, but I think there is more to it. The spectrum of sentient to insentient, is just that a spectrum. When we speak of these concepts we make subtle judgments through the connotation of our words. For example is the robot going to die, or is it going to shutdown? On some level it must be alive, or, at least it was.

Missing Pages

This film mesmerizes me. Missing Pages is a short film by Jerome Oliver about a genius professor and the time machine he creates which leads him into internal battles, a war for humanities humanness, and a reckoning with reality. It is set in a sort of post-singularity minimalist landscape. The entire film is composed of manipulated digital photography with a technique called fotomation. If you enjoy film for films sake then one would argue solely on their use of an experimental approach that it should be watched, but I just really liked the film all around. The music adds a depth which keeps bringing me back.

Above is just the first third of the film. The above clip does not do justice to the film's quality. The clip was removed because it violated terms of service. Anyways, you can get all three parts of the film in high definition full screen for free from itunes here.