Questions and answers with Francis F. Chen

By Jermey N. A. Matthews

Plasma physicist Francis (Frank) Chen has spent more than five decades conducting theoretical and experimental research in magnetic fusion, laser fusion, plasma diagnostics, basic plasma physics, and low-temperature plasma physics. A graduate of Harvard University, Chen was hired in 1954 for Princeton University’s Project Matterhorn, which conducted fusion research for domestic energy production. Using a stellarator built by space physicist James van Allen, Chen was the first to show that electrons could be trapped by a magnetic field for millions of transits; that discovery advanced the field of plasma fusion.

Though formally retired from UCLA, where he has been since 1969, Chen continues to manage an active low-temperature plasma research lab and occasionally advises graduate students. He is author of An Indispensable Truth: How Fusion Power Can Save the Planet (Springer, 2011). Physics Today recently caught up with him to discuss the book.

PT : What motivated you to write this book?

Chen : It has been clear for a long time that being a member of a large experimental team would not be the best way for me to contribute to fusion. What is needed is to get the public interested in supporting it. The media have been exceptionally bad in understanding fusion enough to treat it favorably. In astronomy, there was Carl Sagan; in cosmology, there is Steve Hawking; in string theory there is Brian Greene. I’m not such a personality, but I’ve had success in bringing plasma physics down to the undergraduate level: My textbook, Introduction to Plasma Physics, has been selling well since 1973. However, explaining plasma fusion to a lay audience is an entirely different matter, and I grossly underestimated the difficulty.

PT : Obviously, the title of the book plays off the title of former vice president Al Gore’s documentary, An Inconvenient Truth. To what extent do you think your book can have a similarly successful impact on popularizing fusion power?

Chen : I tried to write in a conversational style for an ordinary, non-scientific audience, but I have not reached a large readership. Book club readers are used to flipping the pages and devouring a 400-page book in a day. They can’t get through two pages with real facts in them. In the climate change chapter, I thought I had used bar charts in a clever way, but my wife says she is used to xy-charts like the Dow-Jones index and can’t understand bar charts. Al Gore got professional help from the entertainment industry. Fusion needs such help. It needs grass-roots support. Fusion can solve Al Gore’s problem of global warming.

The second half of the book is intended to be a resource for physicists and policymakers. It gives the facts about fusion without overselling it. I am hoping that my book can garner support for fusion, perhaps not from the [Obama] administration, which is worried about jobs, but maybe from the Sierra Club, the Nature Conservancy, the Environmental Defense Fund, or EPRI [the Electric Power Research Institute].

PT : What got you interested in fusion research? And are you still professionally engaged in the field?

Chen : Fusion is in my blood, since I was one of the earliest workers in the field. In 1973 a marvelous collaboration with international visitors at UCLA, where I’ve been since 1969, launched the field of parametric instabilities in laser fusion. I then changed to that field for 10 years, after which it evolved into plasma accelerators. But for the last 20 years I have been in low-temperature plasma physics, four orders lower than fusion temperatures.

PT : Cynics like to say that fusion power is always 20 years away. How do you address that sort of skepticism in your book?

Chen : You have to understand how it was before 1990. We didn’t know how to prevent instabilities from destroying plasma confinement, or even what the instabilities were. The skepticism stems from those early days when we were flying blind. But great changes came in the 1990s as large tokamaks were built, confinement got better, and a better understanding of scaling was possible. Supercomputers allowed three-dimensional simulations of toroidal plasmas. High-confinement modes were invented, and internal transport barriers could be made by tailoring the current distribution with radio-frequency power. The problems, which are still hard, are well enough understood now that the ITER machine in France can be planned with a definite schedule. The people who still retain their impressions from 1970 should realize that the situation has changed. That is the main point I was trying to explain in my book.

PT : What is your take on existing clean energy technologies, which aim to fill the gap until fusion power comes online?

Chen : Wind power is very efficient. Solar cells are now cheap. But they are not steady, and you can’t store the electricity for base power. Adding more than 10% of temporary power would destabilize the grid. Carbon sequestration wastes 30% of the energy produced and is very expensive. To store the CO2, you have to compress it, which takes energy, and then inject into a geological reservoir, which could be leak-proof only if you didn’t drill holes into it for injection. Nuclear power is very clean and very safe. Public hysteria is its problem. It should be used until fusion comes online. The power plants and grids can remain the same; the power core simply changes from fission to fusion.

PT : What book are you reading at the moment?

Chen : I’m reading David McKay’s Sustainable Energy—Without the Hot Air (UIT Cambridge, 2009) just to learn how to write more simply.