My first introduction to Vadim Dudnikov was at the International Conference on Ion Sources held in Berkeley, California, in 1989. The following year I had the pleasure of meeting him again at his own laboratory at the Budker Institute of Nuclear Physics in Novosibirsk, Russia. At that time Vadim was already well recognized internationally as a leader in the areas of charge exchange and negative ion production. In 1971 he had discovered the enhancement of negative ion generation in gas discharge plasmas that is brought about by a small admixture of cesium (or other low ionization potential material) to the plasma – the cesiation effect. This method, which dramatically enhances negative ion production, is now a widely used technique for the production of intense, high brightness, negative ion beams. The early work on charge exchange and cesium catalysis carried out at the Budker Institute is well recorded in the literature, and includes the ground-breaking work of Vadim Dudnikov and other key researchers at Novosibirsk – Belchenko, Dimov, Derevyankin, Klenov, Davydenko and others.
There have evolved over the years a great number of embodiments of surface plasma negative ion sources utilizing cesium catalysis. In surface plasma sources, a flux of negative ions is produced when electrons are captured from the cesiated electrode surface by sputtered and reflected particles. Discovery of the physical basis of cesium catalysis has led to the development of surface plasma sources (also called surface production sources, referring to the cesiated surface at which the negative ions are formed) in many laboratories in the USA, France, Germany, Italy, Japan, Russia, U.K. and other countries. Cesium catalysis is used in neutral beam injectors for experimental thermonuclear fusion devices, and the negative ion sources that produce the H– ion beams from which the immensely intense neutral beams are subsequently formed by charge exchange have reached hugely impressive parameters. The International Thermonuclear Experimental Reactor (ITER) presently being constructed at Cadarache, France, calls for two cesium-seeded negative ion sources each producing beams of H– or D– ions at energy 1 MeV and current 73 A (H–) or 40 A (D–) for an on-time of one hour. It is remarkable – the beam current that can be generated has increased by a factor of about 10,000 in the past several decades. To paraphrase Darwin, there is grandeur in this view of science.
Vadim's book describes the origin, history, development and applications of negative ion sources, with emphasis on cesium seeding and those kinds of sources that utilize this phenomenon. It forms an impressive account, including sources that have been developed and used for accelerator injection, ion implantation, accelerator mass-spectrometry, neutral beam injectors, and more. The book will make a valuable contribution to the ion source literature, and will be particularly valuable to the negative ion source community. I hope you enjoy and appreciate it as much as I have.
Ian Brown
Berkeley, California
