specifically on single-component plasmas, with emphasis on pure electron and pure ion plasmas. Research and development in this area is likely to have a significant impact on a wide range of important applications, such as new generations of precision clocks; chemical analysis by improved methods of mass spectrometry; and the accumulation, storage, and transportation of antimatter.
Early research on nonneutral plasmas predated by many decades common usage of the term "plasma." For example, efforts to investigate the equilibrium and stability properties of nonneutral electron flow began with Child (1911), and continued with the work of Langmuir (1923), Llewellyn (1941) and Brillouin (1945), and work on beam-type microwave devices in the 1940s and 1950s. During the past 20 years, interest in the physics of single-component plasmas has grown substantially in such diverse areas as the equilibrium, stability, and transport properties of these plasmas; phase transitions in two- and three-dimensional plasmas; astrophysical studies of large-scale nonneutral plasma regions in the magnetospheres of neutron stars; and the development of positron and antiproton ion sources.
In the case of trapped-ion plasmas, an important synergism has developed between atomic physicists and plasma physicists. Atomic physicists have developed methods to confine and study small collections of ions with great precision. With the addition of more particles, issues of collective oscillations and confinement properties of spatially extended, three-dimensional plasmas become relevant and raise a number of important questions. Study of these questions has illuminated fundamental issues in plasma physics. It has resulted in enhanced capabilities in the creation and control of pure ion plasmas for precision measurements of fundamental constants and for applications such as atomic clocks.
A significant fraction of nonneutral plasma research is closely tied to important technological applications. In contrast to the general development of fundamental plasma experiments that has been hindered significantly in the past two decades due to lack of support, experimental progress in nonneutral plasma research has been excellent, which has stimulated much progress in the theory of nonneutral plasmas. It is the conclusion of the panel that the relative success of research on nonneutral plasmas was due to a strong and dedicated program of support in this area by the Office of Naval Research, with complementary support from the National Science Foundation and the Department of Energy. The panel concludes that this mode of support for nonneutral plasma research should be considered a model for the support of fundamental plasma experiments in the broader area of neutral plasma research.
The following summarizes significant advances in the physics of nonneutral plasmas during the past decade.