Electron beam ion trap bi-annual report 1996/1997

Abstract

The research of the EBIT (Electron Beam Ion Trap) program in N Division of the Physics and Space Technology Directorate at LLNL continues to contribute significantly to the understanding of physical processes with low energy highly charged ions in atomic physics, plasma physics, and material science. Low-energy highly charged ions (up to U92+), provided by the EBIT facilities, provide a unique laboratory opportunity to study high field effects in atomic structures and dynamic interaction processes. The formation, existence, and structure of highly charged ions in astrophysical environments and laboratory plasmas make highly charged ions desirable for diagnosing various plasma conditions. The strong interaction of highly charged ions with matter and the response of solid surfaces make them a sensitive analysis tool and possibly a future capability for materials modifications at the atomic scale (nano technology). These physical applications require a good understanding and careful study of the dynamics of the interactions of the ions with complex systems. The EBIT group hosted an international conference and a workshop on trapped charged particles. The various talks and discussions showed that physics research with trapped charged particles is a very active and attractive area of innovative research, and provides a basis for researchmore » efforts in new areas. It also became obvious that the EBIT/RETRAP project has unique capabilities to perform important new experiments with trapped very highly charged ions at rest, which are complementary to and competitive with research at heavy ion storage rings and other trapping facilities planned or in operation in Europe, Japan, and the United States. Atomic structure research at EBIT provides ever better and more experimental complete benchmark data, supplying data needed to improve atomic theories. Research highlights through 1996 and 1997 include hyperfine structure measurements in H-like ions, QED studies, lifetime and polarization measurements on high-Z highly charged ions. Studies of the interaction of highly charged ions with solid surfaces and thin foil targets reveal new interaction phenomena. The measurements of high secondary ion sputter yields led to the development of a prototype electron/ion emission microscope, which allows simultaneous topographic and chemical composition analysis with high sensitivity and spatial resolution. The enabling technology to trap, confine, and cool hundreds of highly charged ions in a precision Penning trap has been established and first evidence for the formation of a strongly coupled highly charged ion plasma via a sympathetic laser/ion cooling scheme has been observed. The benefits to DOE programs for a continued long term EBIT program are evident. The program requires the application and development of state-of-the-art experimental techniques necessary for spectroscopy, ion confinement and manipulation with spin-off applications in other laboratory programs. Thus, it serves as an excellent training ground for young scientists who will later work on energy-related plasma research or similar areas. It promises new research results towards the growth of our understanding of basic physics phenomena in atomic, nuclear and plasma physics, such as solid phases, astrophysical plasma evolution, and quantum control. This reserach will also provide input for applications in areas like ion beam manipulation and control for materials research. The activities at EBIT have created great interest among scientists from other areas (e.g. biology and environmental sciences) with several new ideas and research directions emerging. External funding for the project has in part been provided by the DOE office of Basic Energy Science (Chemical Science Division) and by NASA.« less