Quantitative experiments with electrons in a positively charged beam
- Heavy-Ion Fusion Science Virtual National Laboratory, Berkeley, California 94720 and Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)
Intense ion beams are difficult to maintain as non-neutral plasmas. Experiments and simulations are used to study the complex interactions between beam ions and (unwanted) electrons. Such ''electron clouds'' limit the performance of many accelerators. To characterize electron clouds, a number of parameters are measured, including total and local electron production and loss for each of three major sources, beam potential versus time, electron line-charge density, and gas pressure within the beam. Electron control methods include surface treatments to reduce electron and gas emission, and techniques to remove electrons from the beam or block their capture by the beam. Detailed self-consistent simulations include beam-transport fields and electron and gas generation and transport; these compute unexpectedly rich behavior, much of which is confirmed experimentally. For example, in a quadrupole magnetic field, ion and dense electron plasmas interact to produce multi-kV oscillations in the electron plasma and distortions of the beam velocity space distribution, without the system becoming homogeneous or locally neutral.
- OSTI ID:
- 20975080
- Journal Information:
- Physics of Plasmas, Vol. 14, Issue 5; Other Information: DOI: 10.1063/1.2436850; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 1070-664X
- Country of Publication:
- United States
- Language:
- English
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