10 Questions for Steven Cowley, New Director of the Princeton Plasma Physics Laboratory

Steven Cowley, a theoretical physicist and international authority on fusion energy, became the seventh Director of the Princeton Plasma Physics Laboratory (PPPL) on July 1 and will be Princeton professor of astrophysical sciences on September 1. Most recently president of Corpus Christi College and professor of physics at the University of Oxford in the United Kingdom since 2016, Cowley previously was chief executive officer of the United Kingdom Atomic Energy Authority (UKAEA) and head of the Culham Centre for Fusion Energy. He earned his doctorate at Princeton University in astrophysical sciences in 1985 and was a staff scientist at PPPL from 1987 to 1993. He is a Fellow of the Royal Society and of the Royal Academy of Engineering, and was knighted by the Queen of England in June 2018 for his role in fusion science.

1. Why are you returning to the Princeton Plasma Physics Laboratory?

The short answer is because I think it will be fun. The science and technology at PPPL is world-leading and I am looking forward to being part of that capability. I am also deeply committed to making fusion power a reality, and PPPL is central to that mission.

2. What do you hope to accomplish?

Although it is clear that fusion is possible, we do not yet have all the knowledge to make fusion cost-effective. Specifically, we need to create innovations that will bring down the cost and scale of future fusion facilities. The National Spherical Torus Experiment-Upgrade (NSTX-U) at PPPL is critical to exploring the promise of compact and cost-effective spherical devices that can deliver such innovation. We are going to finish the reconstruction of the NSTX-U and bring the device back as the world’s strongest spherical tokamak, to fulfill its mission in fusion energy research.

3. Why is fusion important; what are its benefits?

Fusion is the perfect way to make energy: the fuel is abundant, it has low environmental impact and it is safe. Imagine an energy source that can last millions of years, is widely available, and does not harm the planet — inexhaustible and zero-carbon. Controlled fusion is clearly difficult to do on Earth, but not impossible as the results of 1990s experiments, such as the Tokamak Fusion Test Reactor at PPPL, and the Joint European Torus show. In those experiments we actually created fusion power. This source of energy is simply too important not to pursue.

4. What is plasma and why is it so special?

Plasma is the fourth state of matter where the electrons are separated from the nuclei and move freely. Plasma makes up 99 percent of the visible universe — stars like our sun are giant balls of plasma. But the behavior of plasma is extraordinarily complex, and invariably turbulent. In the last decade, theory and computation have finally become powerful enough that we can simulate the behavior of real turbulent plasmas, creating an understanding that will help us produce controlled fusion on Earth.

5. Are there other advantages to fusion research, besides providing virtually unlimited energy?

The science of plasmas has been developed largely for fusion research. But the understanding that has been achieved has been applied to plasmas in astrophysics, space physics and to numerous industrial applications. PPPL has played a role in all areas of plasma research — that is surely one of the many strengths of the laboratory. Fusion research has also been a driver for technological innovation — from high-powered particle beams to strong magnetic field superconducting coils. So the spinoffs are many.

6. Why is it taking so long? Put another way, what are the current challenges to providing fusion energy and how (and when) will we overcome them?

It has taken longer than expected to make progress in fusion, in large part because we did not expect that confined plasmas would be so turbulent and difficult to control. But the progress has been extraordinary when you consider the extreme complexity of the physics in our experiments. I see four areas that must be improved to overcome the challenges. We must:

Confine the plasma better, or in other words, decrease the energy loss from the plasma;

Increase the pressure of the plasma that we confine (in physics talk, increase the plasma beta) to get the nuclei to fuse more rapidly;

Find a way to handle the huge exhaust heat, and;

Find materials that can withstand the battering of neutrons in the fusion device. It is truly a grand challenge — as much an engineering and materials science problem as it is a physics challenge.

7. There are different types of fusion devices all around the world. Do we need them all?

We certainly need them all. In fact, we need more. There are many unexplored magnetic configurations. For example, the compact stellarator ideas that were developed at Princeton over a decade ago have never been explored — and they are beautiful ideas. There are other types of approaches to fusion in addition to magnetic confinement. The best fusion configuration is not clear and we need to experiment with many different types of machines to determine the best path forward.

8. PPPL has an extensive staff of savvy scientists. What else besides fusion are they working on?

There is so much that I cannot mention it all. I shall only highlight some examples. The growth of astrophysical plasma research at PPPL is of great attraction to me. I have a long-standing interest in the origin of magnetic fields in the universe — so called magneto-genesis (a rather pretentious name!). Some of our smartest young people are thinking deeply about that problem. It is also wonderful to see PPPL’s instrument-building capability in the form of the X-ray spectrometer making inroads into other areas of research. The impact of PPPL’s industrial research is profound and I hope we can continue to strengthen our impact on the economy.

9. Can commercial fusion energy be a reality?

You bet! It is inevitable that eventually fusion energy will play a significant role in world energy production. Our job is to make it happen soon.

10. What are some of your hobbies or interests besides plasma physics?

I was once a very mediocre trumpet player; I remain a huge jazz fan. The Golden State Warriors play the prettiest basketball I have ever seen. But if I have a spare couple of hours I like to do algebra — once a nerd always a nerd.