Ultracold charged particle sources

Ultracold plasmas are produced by near-threshold photoionization of laser-cooled and trapped atoms. In turn, these plasmas are a novel source of electron and ion beams that for instance provide a route to achieving high brightness from an extended source due to the low temperature. Application of such ultracold beams in focused ion beam instruments is actively being pursued. Here, reducing disorder-induced heating and achieving low energy spread lead to competing demands in order to optimize focal spot size. In electron diffraction, cold sources allow for ultrashort pulses of substantial charge with relatively large coherence length. Our ultimate goal is to apply these to studies of the structural dynamics of macromolecules.