Effects of space charge and reactive wall impedance on bunched beams

Space charge and reactive wall impedance create longitudinal forces inside the bunch which change the incoherent phase oscillation frequency, the bunch length and the size of the RF-bucket. These effects have been investigated with bunched beams in the ISR. By measuring the shift of the quadrupole mode phase oscillation frequency, the strength of the self-forces was determined. The inductive wall is dominant and its impedance (divided by the mode number) was measured to be mod Z mod /n approximately=26 Ohms. An increase of bunch length with current was measured. The reduction of the bucket size affects the stacking process. By correcting for it, an increased density of the stacked beam was achieved. (14 refs)

Thoughts and spirits by wireless: imagining and building psychic telegraphs in America and Britain, circa 1900-1930

This is the author accepted manuscript. The final version is available from Taylor & Francis via the DOI in this record.This paper revises current understandings of the connections between electrical and psychic forms of communication in the early twentieth century. It builds on and moves beyond scholarly studies that explore the metaphorical and analogical uses of electrical communication in understanding telepathy, spiritualism and other psychic phenomena. I argue that in American and British cultures of wireless telegraphy, electrical experimentation, psychical research and spiritualism, there were sincere attempts to extend electrical-psychic analogies into technological thinking and realisation. Inspired by debates about telepathy, brain waves and other psychic effects, members of these cultures imagined and constructed electrical communication technologies that would address a range of psychic puzzles. Although the technological solutions to psychic puzzles ultimately proved inconclusive, they provide historians with striking insights into the role of ‘irrational’ topics in shaping imagined and actual technological development