Preface

Power production and its consumption and distribution are among the most urgent problems of civilization. Despite huge efforts and positive dynamics in introducing renewable sources of energy such as solar and wind, nuclear power plants still remain the major source of carbon-free electric energy. However, the deposits of nuclear fuel are limited. Fusion can be an alternative to fission for the foreseeable future. Nuclear fusion takes place in the sun and provides energy for life on Earth. Research in the field of controlled nuclear fusion has been ongoing for almost 100 years. Since 1920, many physics and engineering problems of fusion have been successfully resolved, and several fusion technologies have been implemented in other fields of science and technology. Magnetic confinement systems are the most promising for effective implementation, and the International Thermonuclear Experimental Reactor (ITER) is under construction in France. ITER is designed to demonstrate a 10-fold return on energy.

To accomplish nuclear fusion on Earth, we have to resolve a wide scope of scientific and technological problems. This is why the nuclear fusion international community consists of a large number of divisions. For example, nuclear fusion problems start from those of nuclear physics, which demonstrate the basics of energy release from the fusion of light atoms to heavier atoms. To realize controlled nuclear fusion, many schemes have been discovered and suggested, for example magnetic confinement and inertial synthesis. Magnetic confinement systems can be divided into tokamaks and stellarators. These two types of nuclear fusion devices can in turn be classified into spheromaks and torsatrons. Plasma is proposed for creating the conditions for controlled nuclear fusion. Plasma physics and engineering are also a very large part of physics. Plasma used to be unstable and needed additional efforts to prevent plasma discharge breakdown. Many physicists have devoted themselves to studying plasma instabilities and searching for ways to suppress or avoid these instabilities. Electromagnetic waves propagate in the fusion plasmas. The waves can be used for plasma heating up to the temperatures of nuclear fusion reactions. We also have to understand how to excite these waves and how to propagate them. These waves interact with the plasma, the walls of the chamber, and with each other, and we need to understand how they are absorbed. Many problems are associated with designing and constructing the antennae to excite electromagnetic waves and the power supply for the antennae. We have to know how to extract the energy from the future thermonuclear power plant. Finally, we need materials to produce a chamber in which the plasmas can be "boiled." These materials should be stable to significant heat and mechanical loads, as well as to undesirable interaction with aggressive hot plasmas.

For decades, many national and international journals have published papers devoted to fusion-related topics. It is clear that any single book cannot cover all the topics of nuclear fusion research. This monograph includes selected chapters of nuclear physics and mechanical engineering within the scope of nuclear fusion.

In the first chapter, "Nuclear Fusion: Holy Grail of Energy," harnessing the energy produced in a nuclear fusion reaction in a laboratory environment is discussed.

Various research programs in the field of controlled nuclear fusion are also discussed. Emphasis is given to overcoming some of the technological challenges, such as surmounting the Coulomb barrier, confining the plasma, and achieving the ignition temperature.

The second chapter, "Fusion Reaction of Weakly Bound Nuclei," is devoted to comparison of a semiclassical and full quantum mechanical approach to study the total fusion reaction cross-section and the fusion barrier distribution for several systems such as 6 Li + 64Ni, 11B + 159Tb, and 12C + 9 Be. The results obtained from the numerical calculations based on these two approaches are compared with the available experimental data.

Thorium is a fertile element that can be applied in the conceptual blanket design of a fusion/fission hybrid energy reactor, in which 232Th is mainly used to breed 233U by capture reaction. The activation γ-ray offline method for determining the thorium reaction rates is developed in the third chapter, "Fusion Neutronics Experiments for Thorium Assemblies" The 232Th (n, γ), 232Th (n, f), and 232Th (n, 2n) reaction rates in assemblies are measured by using ThO2 foils and an HPGe γ spectrometer.

The fourth chapter, "Mechanical Mockup of IFE Reactor Intended for the Development of Cryogenic Target Mass Production and Target Rep-Rate Delivery into the Reaction Chamber" describes the efforts that are underway at the Lebedev Physical Institute of Russian Academy of Sciences to arrange target production and delivery into the reaction chamber for inertial fusion. The current status and future trends of developments in the area of advanced target technologies are discussed.

Section 1

Selected Problems of Nuclear

Physics

1

While fusion plasmas are very hot, magnetic coils should be very cold to provide stable static magnetic fields of high intensity. The mechanical behavior of the cable in a conduit conductor is studied in the fifth chapter, "The Mechanical Behaviors of Cable-in-Conduit Conductor for the ITER Project," because of its high importance for understanding the mechanical response and assessing the safety of the superconducting structures in the ITER.

This book is intended for nuclear scientists, engineers, and advanced students with a basic understanding of nuclear fusion and power reactors. It discusses several issues of nuclear physics as well as those of mechanical engineering related to nuclear fusion.

> **Igor Girka, Professor** Corresponding Member of National Academy of Sciences of Ukraine, V. N. Karazin Kharkiv National University, Ukraine

Section 1
