UBC Theses and Dissertations
The evolution from Rydberg gas to plasma in an atomic beam of Xe : with comparative simulations to a strongly blockaded Rydberg gas of Rb Hung, Jachin
We study a supersonic beam of cold, dense, xenon Rydberg atoms as it evolves to an ultracold plasma. At early times, while the free electron density is low, d-series Rydbergs atoms undergo long-range ℓ-mixing collisions producing states of high orbital angular momentum. These high-ℓ states drive dipole-dipole interactions where Penning ionization provides a seed of electrons in a cloud of Rydberg atoms excited into the 51d state. The electron density increases and reaches the threshold for avalanche into plasma at 25 μs. After 90 μs the plasma becomes fully formed developing rigidity to a 432 V/cm ionizing field as well as sensitivity to a weak 500 mV/cm field. A shell model was developed to understand the dynamics behind this process. In addition, in collaboration with the Weidemüller group, a model was developed using Penning ionization to seed the spontaneous avalanche of a cloud of strongly blockaded Rydberg atoms in a MOT.
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