Background, Basics, and Some IEC Experiments

Abstract

This book is dedicated to the field of inertial electrostatic confinement (IEC) fusion. Confinement of a hot plasma for fusion or plasma processing is difficult because the hot plasma prevents use of a material confinement vessel. IEC fusion is one of the various methods that can be used to confine a hot fusion plasma. As will be apparent from this book, IEC fusion offers many potential advantages, including simplified support structures and the ability to create non-Maxwellian plasmas that can be used with a variety of fusion fuels. However, a majority of fusion scientists are studying magnetic field confinement in the form of a closed torus (e.g., a Tokamak). Alternately, the fast pulsed approach used in laser fusion attempts to rapidly compress the plasma to an ultrahigh density, and the inertia of the ions maintains the high density long enough such that the fusion energy produced exceeds the input compression energy. Thus, this approach was termed inertial confinement fusion (ICF). These two approaches have led to current major fusion experiments: the international ITER Tokamak in France and the National Ignition Fusion (NIF) experiment using a laser at the Lawrence Livermore National Laboratory (LLNL). Both confinement approaches require very large and complex units, costing billions of dollars to construct. A number of alternate confinement concepts have been proposed with the objective of achieving smaller, less expensive power plants. Some also have the objective of burning “advanced fuels,” defined loosely as any non-D–T fuels [1]. Examples include deuterium–deuterium (D–D), deuterium–helium-3 (D–3He), and hyrdrogen–boron-11 (H–B11). One objective of using such fuels is to minimize neutron production, thus neutron-induced radioactivity and damage in structural materials. A second objective is to reduce or eliminate the need for tritium handling and breeding, greatly simplifying the chamber blanket systems. Hydrogen–boron-11 (or H–B11, often termed p–B11) is ideal with a plentiful fuel supply and a reaction that produces three energetic alpha particles with no neutron (hence aneutronic). However, burning p–B11 generally requires very high ion temperatures (~ 170 keV vs. ~ 25 keV for D–T) and low electron temperatures (< 1/5 the ion temperature), plus elimination of magnetic fields within the hot fusing plasma to minimize Bremsstrahlung and cyclotron radiation losses, respectively. The IEC is one of only a few alternate confinement approaches that theoretically offer the highly non-Maxwellian plasma conditions needed to burn p–B11. Experimental demonstration of this is a key objective for IEC experiments but is very challenging, as discussed in later chapters.