Stewart C. Prager, the director of the Department of Energy’s Princeton Plasma Physics Laboratory and a professor of astrophysical sciences at Princeton University, here offers a fresh defense of continued substantial support for research on extracting usable energy from nuclear fusion.

His “Your Dot” contribution builds on a recent fusion post by Burton Richter, a Nobelist in physics and author of a valuable book on energy, and another from Robert L. Hirsch, who directed the country’s fusion energy program in the 1970s. Here’s Prager’s post:

We need to keep our eyes on fusion as a transformative source of energy for the world. There are many powerful reasons why we need to forge ahead.

As budget negotiations heat up, so does the debate over the balance between investments in the long-term future and short-term necessities. Fusion is a long-term opportunity that will transform how we energize our society. The fact that ignition in a large American experimental inertial confinement fusion facility did not occur as hoped by Sept. 30 has sadly raised questions about the scientific legitimacy of that pursuit. That the scientists did not meet their goal by that day probably has little bearing on that field’s ultimate success. Importantly, this non-event should not bear any relation to the fate of other vital work centering on an entirely different approach known as magnetic fusion.

The magnificent lasers at the Lawrence Livermore National Laboratory’s National Ignition Facility are aimed to compress a pellet of fusion fuel such that it “ignites” – converts the energy of the lasers that bombard the pellet into fusion energy. The lasers work spectacularly well but the problem of fusion ignition is scientifically rich and complex. So far at least, the pellets have not yet behaved as expected and the milestone of ignition has not yet been achieved. This, of course, should not dull interest in the American inertial confinement fusion program: Not achieving a major scientific result by a pre-determined and artificial deadline is far from a failure.

Further, the fact that conquering this complex problem in laser fusion has not been “on schedule” has nothing to say about progress in magnetic fusion – it has been and continues to be remarkable.

Those with a long memory will recall the very early optimism about fusion energy that existed in the late 1950s and 1960s. On the heels of the quick success in moving fission energy forward, it was thought practical fusion would follow closely behind. Instead, the world’s scientists ran into an unexpected barrier — the immense physics complexity and seeming impossibility of taming fusion plasmas.

The ensuing decades have seen an intense scientific focus on what is truly a grand scientific challenge. Scientists now are teasing out the secrets of complex multi-scaled layers of turbulence in plasmas, the movement of particles through those plasmas, their interaction with magnetic fields, and numerous other phenomena that impact the plasma’s ability to be harnessed as an energy source. This focus in magnetic fusion has driven the development of a new scientific field, plasma physics, with huge benefits for science in general – from understanding cosmic plasmas to employing these hot, ionized gases for computer chip manufacturing.

On the energy front, we have advanced from fusion energy production of milliwatts in the 1970s to 16 megawatts (for a duration of 1 second) in the 1990s. With our existing underpowered machines, magnetic fusion scientists are producing and producing close to fusion energy-grade plasmas around the world on a daily basis. We are confident that abundant fusion energy can be produced on a very large scale and are now focused on the remaining physics and engineering challenges to make it practical and attractive.

The next major experimental step in magnetic fusion is ITER – the international experiment that will generate 500 megawatts of fusion power, at a physical scale of a power plant. Under construction in France, ITER will begin operation within ten years. It involves participation of the entire developed world, with the ITER partners representing the governments of half the world’s population. The scientific basis for ITER was separately scrutinized and approved by scientific panels in each of these nations. ITER is large, complex, and full of challenges. But, the likelihood of scientific success is high.

Most nations involved in ITER have robust fusion research programs that are essential to tackle other key scientific and technical issues. With these accompanying programs, we would be ready to operate a demonstration fusion power plant following ITER about 25 years from today.

The charge by some that both inertial and magnetic fusion have been beset with failure is unwarranted. These include remarks in a commentary by Dr. Burton Richter in the Oct. 18 Dot Earth blog: “Both approaches have gone from failure to ever larger failure, but each time a great deal has been learned…”

In fairness, the comment is preceded by brief, informative technical capsules. As a fusion-knowledgeable scientist who does not work in fusion energy research, Dr. Richter includes some supportive comments for the fusion program, tempered by discerning skepticism. But, for fusion scientists, Dr. Richter’s comments on failure are difficult to understand. We are unaware of any major project failures in magnetic fusion research. Quite the opposite: One of the key reasons that ITER was funded across the world is that a series of ever larger experiments have been so successful as to provide confidence that the yet larger ITER will be similarly successful.

Other commentary has appeared, offering incorrect information. In a separate Dot Earth commentary concerning magnetic fusion on Oct. 19, Dr. Robert Hirsch, an administrator of the fusion energy program at the U.S. Atomic Energy Commission in the 1970s, offers views reflecting the state of the field at the time of his departure from the AEC some 35 years ago. His view is framed by stating that fusion must be made practical, which means economically and technologically attractive. This is certainly correct and indeed, the criteria for such practicality have provided significant guidance to fusion research for decades. Dr. Hirsch cites a series of challenges that he thinks are roadblocks, but are not. He worries that the energy stored by superconducting magnets poses a serious threat and regulatory burden. This is not so. ITER has proven otherwise. France’s strict nuclear regulatory authorities have concluded the magnets pose no radiological safety concerns for the public. Dr. Hirsch states that the radioactive materials of a fusion reactor will be a major problem. This also is not so. The amount and toxicity is orders of magnitude less than for fission. Dr. Hirsch would be interested to learn that the rigorous French licensing regime is very successfully nearing completion. Licensing, although requiring significant efforts, will not be a barrier to fusion.

Some, like Dr Hirsch, have suggested that fusion machines are so large and complex that they will never be cost competitive. No one knows the ultimate costs, but our best engineering analyses indicate that, with some luck, fusion can indeed be cost- competitive. As an alternative to the mainline approaches to fusion energy, Dr. Hirsch puts forth his research idea from the 1970s of inertial electrostatic confinement (IEC). I agree that the fusion program very much needs to pursue multiple approaches, even within magnetic fusion. But extensive peer review has found IEC far more difficult to achieve than the ITER and related approaches in magnetic fusion.

Fusion is a nearly ideal energy source – essentially inexhaustible, clean, safe, and likely available to all nations. When proven practical, it will transform our energy future. At this moment, research investment by the rest of the world – China, Korea, the EU – is surging in magnetic fusion, while the U.S. investment is stagnating. The U.S. is at a turning point. We either maintain our long-developed leadership position in this energy and science frontier, or slip behind as other nations take the fruit of decades of scientific research – much of it from the U.S. – and convert it into a practical energy source for powering the world.