Ultrafast electron cooling in an expanding ultracold micro-plasma
Abstract
Strong-field ionization of a quantum gas by ultrashort laser pulses allows creating electrons and ions with tunable excess energy. A single femtosecond laser pulse focused to a micrometer-sized waist can ionize up to several thousand atoms out of a Bose-Einstein condensate, thus triggering the formation of strongly coupled ultracold plasmas. We report on the observation of electron cooling in an expanding micro-plasma from initially 5000 K electron temperature to about 1 K within a few hundred nanoseconds. Our experimental setup grants access to the electronic kinetic energy distribution with meV resolution. Furthermore, we have performed numerical simulations of the collective Coulomb driven plasma dynamics which are in excellent agreement with the measurements. The simulations reveal an efficient energy transfer to the ionic system within the first ten picoseconds.
This work is funded by the Cluster of Excellence 'The Hamburg Centre for Ultrafast Imaging' of the Deutsche Forschungsgemeinschaft (DFG) - EXC 1074 - project ID 194651731.- Publication:
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APS Division of Atomic, Molecular and Optical Physics Meeting Abstracts
- Pub Date:
- 2020
- Bibcode:
- 2020APS..DMPM06005S