Heidelberg 2015 – scientific programme

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A: Fachverband Atomphysik

A 22: Ultra-cold atoms, ions and BEC III (with Q)

A 22.1: Talk

Wednesday, March 25, 2015, 11:00–11:15, M/HS1

Space charge dynamics and diffraction with ultracold electron and ion bunches — •Robert Scholten, Dene Murphy, Rory Speirs, Dan Thompson, Joshua Torrance, Richard Taylor, Andrew McCulloch, and Ben Sparkes — School of Physics, University of Melbourne, Australia

Cold electron and ion sources based on photoionisation of laser cooled atoms provide a unique system for investigating Coulomb interactions within complex charged particle bunches and for high coherence diffractive imaging. Space-charge driven expansion in charged particle beams is of critical importance for applications including electron and ion microscopy, mass spectrometry, synchrotrons and x-ray free electron lasers, and in electron diffraction where space-charge effects constrain the capacity to obtain diffraction information. Self-field effects are often difficult to observe because of thermal diffusion with traditional sources. Cold atom sources produce ions with temperatures of a few mK, such that subtle space-charge effects are apparent. We illustrate the capabilities through detailed investigation of a complex ion bunch shape, showing collective behaviour including high density caustics and shockwave structures arising from long-range interactions between small charge bunches. We also demonstrate ultra-fast diffraction with cold electrons.