Detailed observation of space–charge dynamics using ultracold ion bunches

Abstract

Control of Coulomb expansion in charged particle beams is of critical importance for applications including electron and ion microscopy, injectors for particle accelerators and in ultrafast electron diffraction, where space-charge effects constrain the temporal and spatial imaging resolution. The development of techniques to reverse space-charge-driven expansion, or to observe shock waves and other striking phenomena, have been limited by the masking effect of thermal diffusion. Here we show that ultracold ion bunches extracted from laser-cooled atoms can be used to observe the effects of self-interactions with unprecedented detail. We generate arrays of small closely spaced ion bunches that interact to form complex and surprising patterns. We also show that nanosecond cold ion bunches provide data for analogous ultrafast electron systems, where the dynamics occur on timescales too short for detailed observation. In a surprising twist, slow atoms may underpin progress in high-energy and ultrafast physics.

Extraction dynamics of electrons from magneto-optically trapped atoms

“…[4][5][6][7][8][9] As we are primarily interested in the development of an ultracold electron source, we do not discuss the extensive work which has been carried out on the development of ultracold ion sources. Many of the traits which make a cold atom electron source appealing are shared with cold ion sources which have facilitated, for example, the observation of space charge dynamics 10 and high-resolution imaging. 8,11 A review of cold atom ion sources is presented in Ref.…”

Ion friction at small values of the Coulomb logarithm

“…These systems have enabled studies of plasma dynamics and evolution in a highly idealized environment [32,33], serving, in a way, as high-energy-density plasma simulators [34,35]. They are generated by resonantly photo-ionizing mK-temperature atoms [36][37][38][39][40] or molecules [41,42]. The initial plasma density (10 7 to 10 12 cm −3 ) and electron temperature (5 to 500 K) are selected with small uncertainties.…”

A high repetition deterministic single ion source

“…Alongside the established ion sources [13,14], progress in field ionization sources [15,16] and new sources based on photoionization of ultracold atoms [17] extend the range of available species and possible applications. Only little work has been undertaken so far to control the number of ions in a beam and to trace the space-time trajectory of the individual ions [18]. Having full control over each single ion in a beam [19] would, however, offer a complete new portfolio of ion beam techniques, bridging quantum optical and materials science applications [20].…”