Expansion of ultracold neutral plasmas with exponentially decaying density distributions
Abstract
We present a study of the expansion of an ultracold neutral plasma (UCNP) with an initial density distribution that decays exponentially in space, created by photoionizing atoms shortly after their release from a quadrupole (or biconic cusp) magnetic trap. A characteristic ion acoustic timescale is evident in the evolution of the plasma size and velocity, indicating that the dynamics are reasonably well described by a model of hydrodynamic expansion of a quasi-neutral plasma. However, for low plasma density and high initial electron temperature, excess ion kinetic energy in the vicinity of the central density peak suggests significant local non-neutrality at early times. Observations are compared to the well-understood self-similar expansion of a UCNP with an initial Gaussian density distribution, and a similar scaling law describes the evolution of plasma size for both cases.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Feb 01, 2021
- Source ID
- 10.1063/5.0042460
Entities
People
- Grant M Gorman
- M. K. Warrens
- Stephen Bradshaw
- Thomas C Killian
Organizations
- Air Force Office of Scientific Research
- National Science Foundation
- Rice University