By John Sheffield
Elsevier
Hardback: €50.95
E-book: €50.95
One thing the reader learns from this book is that the path towards achieving controlled nuclear fusion is not smooth or free from the vagaries of funding agencies. You also realize how incredibly difficult the problem is.
The fusion process is well understood and a number of experiments around the world have verified the principles. However, it still has to be demonstrated that a gain in energy can be achieved. There are two main approaches to accomplishing this. One is the magnetic confinement of deuterium–tritium plasma and the other is laser compression of a cryogenic layer of deuterium and tritium in a pellet. Sheffield takes the reader on a personal journey in the quest for a fusion device capable of producing net energy gain, recounting some amusing moments from his career as he oscillated between Europe and the US. Interspersed between the many stories, there is an historical account of modern fusion activity, covering both science and politics.
His research career in fusion started when he joined the United Kingdom Atomic Energy Authority laboratory at Harwell, close to Oxford, in 1958. There he began working on shock-wave experiments to reach the temperatures necessary for fusion. In these early shock experiments, as in all fusion experiments, high-voltage systems were the norm – and where large amounts of electrical energy are stored, sparks and explosions can occur. Sheffield recounts several stories of such explosions, sparks and fires. He was always amazed that no one was seriously injured – this was not a result of stringent safety precautions, but sheer luck. Today, safety officers reading these stories of capacitors accidentally discharging megajoules of energy would swiftly close down the site. Sheffield’s early experiments on shock waves were indeed shut down, but because they were a dead end in terms of fusion. Nevertheless, by the end they had amassed a wealth of data on collisionless shock waves. This science of collisionless shocks is now an active research area in space physics and astrophysics.
The imagination of fusion scientists shows no bounds when it comes to thinking of new magnetic-field topologies to contain plasma with a temperature of 100 million degrees. However, the closing down of machines is a major problem in fusion research, which has resulted in there being today only a few major facilities, such as the Joint European Torus in the UK, the ITER international tokamak device being built in France, and the National Ignition Facility in the US, where a laser-fusion machine is operating and producing interesting results. Sheffield describes the “dinosaur chart” he created when accused by a congressional staffer that fusion scientists never wanted to close any line of research or a machine. The chart shows how projects are closed or cancelled. A parallel in accelerator physics is the Superconducting Super Collider (SSC) in the US, but most of the machines described in the dinosaur chart were being used for science, unlike the SSC, which was never completed.
The book is, in a sense, a short history of the quest for fusion, mainly through magnetic confinement, and the various stories paint an interesting picture of some of the characters in the field. A number of them are well known in fusion circles, but little known outside, so this will interest readers who are already working in fusion or plasma physics, where the stories and characters will be familiar. A few exceptions include Edward Teller, Andrei Sakharov, Lev Artsimovich and Marshall Rosenbluth.
There is some useful information about the various fusion processes and while the book is not comprehensive, it gives the main ideas – even if briefly – behind magnetic and inertial fusion. It conveys a strong message that fusion is well worth the effort, even though it is likely to be decades before energy is delivered to the Grid. It will appeal to those who have an interest in fusion and in the psychology behind scientific activity.
