Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:0705.3056 · Physical Review Letters

Experimental Realization of an Exact Solution to the Vlasov Equations for an Expanding Plasma

S. Laha, Priya Gupta, Clayton E. Simien, H. Gao, Jose Castro, Thomas Pohl, T. C. Killian

Published Oct 8, 2007• 68 citations
arXivHTMLPDF

Abstract

We study the expansion of ultracold neutral plasmas in the regime in which inelastic collisions are negligible. The plasma expands due to the thermal pressure of the electrons, and for an initial spherically symmetric Gaussian density profile, the expansion is self-similar. Measurements of the plasma size and ion kinetic energy using fluorescence imaging and spectroscopy show that the expansion follows an analytic solution of the Vlasov equations for an adiabatically expanding plasma.

DOI
10.1103/physrevlett.99.155001

Related papers

Ultracold neutral plasma expansion in two dimensions

E. A. Cummings, J. E. Daily, Dallin Durfee +1 more

An isothermal model of ultracold neutral plasma expansion is extended to systems without spherical symmetry. It is used to interpret new fluorescence measurements on ultracold neutral calcium plasmas. For a self-similar expansion, the fluid equations are solved both analytically and numerically. The density and velocity solutions are used to predict fluorescence signals induced by a laser beam weakly focused into the plasma. Despite the simplicity of the model, predicted fluorescence signals reproduce major features of the experimental data.

arXiv:physics/0508217•Physics of Plasmas•Dec 1, 2005•27 citations

Electron-Temperature Evolution in Expanding Ultracold Neutral Plasmas

Priya Gupta, S. Laha, Clayton E. Simien +4 more

We have used the free expansion of ultracold neutral plasmas as a time-resolved probe of electron temperature. A combination of experimental measurements of the ion expansion velocity and numerical simulations characterize the crossover from an elastic-collision regime at low initial Gamma(e), which is dominated by adiabatic cooling of the electrons, to the regime of high Gamma(e) in which inelastic processes drastically heat the electrons. We identify the time scales and relative contributions of various processes, and we experimentally show the importance of radiative decay and disorder-induced electron heating for the first time in ultracold neutral plasmas.

arXiv:0705.3416•Physical Review Letters•Aug 17, 2007•67 citations

Ultracold neutral plasma expansion in two dimensions

Cummings, E A, Daily, J E, Dallin Durfee +1 more

An isothermal model of ultracold neutral plasma expansion is extended to systems without spherical symmetry. It is used to interpret new fluorescence measurements on ultracold neutral calcium plasmas. For a self-similar expansion, the fluid equations are solved both analytically and numerically. The density and velocity solutions are used to predict fluorescence signals induced by a laser beam weakly focused into the plasma. Despite the simplicity of the model, predicted fluorescence signals reproduce major features of the experimental data

•Aug 30, 2005•27 citations

Simulating The Expansion Of Ultracold Neutral Plasmas Using A Kinetic Code In Spherical Coordinates

Lucas J. Stanek, J. Haack, Michael S. Murillo

Ultracold neutral plasmas (UNPs) are created in a vacuum by photoionizing laser-cooled atoms. The expansion of UNPs begins as a non-equilibrium system that quickly relaxes to a local equilibrium state [1] . We aim to quantify and compare the transport processes that govern the relaxation to equilibrium in the expanding UNP. Using a 1D-1V kinetic code in spherical coordinates, we model the radial expansion of an UNP. We compare our simulation results against analytic expressions to determine where the expansion of the UNP is adiabatic or isothermal. We carry out simulations for various initial density distributions such as an exponentially decaying density distribution [2] . We ultimately aim to extend this approach to a 1D-3V multi-component kinetic code that incudes collisions [3] .

IEEE International Conference on Plasma Science (ICOPS)•May 22, 2022•0 citations

Expansion of ultracold neutral plasmas with exponentially decaying density distributions

M. K. Warrens, Grant M. Gorman, S. J. Bradshaw +1 more

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.

arXiv:2012.14577•Physics of Plasmas•Feb 1, 2021•11 citations

Electron trapping in freely expanding ultracold neutral plasmas

R. Ayllon, Hugo Terças, José Tito Mendonça

We report on the self-induced electron trapping occurring in an ultracold neutral plasma that is set to expand freely. At the early stages of the plasma, the ions are not thermalized which follow a Gaussian spatial profile, providing the trapping to the coldest electrons. In the present work, we provide a theoretical model describing the electrostatic potential and perform molecular dynamics simulations to validate our findings. We show that in the strong confinement regime, the plasma potential is of a Thomas-Fermi type, similar to the case of heavy atomic species. The numerically simulated spatial profiles of the particles corroborate this claim. We also extract the electron temperature and coupling parameter from the simulation, so the duration of the transient Thomas-Fermi is obtained.

arXiv:1804.06957•Physics of Plasmas•Mar 1, 2019•5 citations
We study the expansion of ultracold neutral plasmas in the regime in which inelastic collisions are negligible. The plasma expands due to the thermal pressure of the electrons, and for an initial spherically symmetric Gaussian density profile, the expansion is self-similar. Measurements of the plasma size and ion kinetic energy using fluorescence imaging and spectroscopy show that the expansion follows an analytic solution of the Vlasov equations for an adiabatically expanding plasma.
An isothermal model of ultracold neutral plasma expansion is extended to systems without spherical symmetry. It is used to interpret new fluorescence measurements on ultracold neutral calcium plasmas. For a self-similar expansion, the fluid equations are solved both analytically and numerically. The density and velocity solutions are used to predict fluorescence signals induced by a laser beam weakly focused into the plasma. Despite the simplicity of the model, predicted fluorescence signals reproduce major features of the experimental data.
We have used the free expansion of ultracold neutral plasmas as a time-resolved probe of electron temperature. A combination of experimental measurements of the ion expansion velocity and numerical simulations characterize the crossover from an elastic-collision regime at low initial Gamma(e), which is dominated by adiabatic cooling of the electrons, to the regime of high Gamma(e) in which inelastic processes drastically heat the electrons. We identify the time scales and relative contributions of various processes, and we experimentally show the importance of radiative decay and disorder-induced electron heating for the first time in ultracold neutral plasmas.
An isothermal model of ultracold neutral plasma expansion is extended to systems without spherical symmetry. It is used to interpret new fluorescence measurements on ultracold neutral calcium plasmas. For a self-similar expansion, the fluid equations are solved both analytically and numerically. The density and velocity solutions are used to predict fluorescence signals induced by a laser beam weakly focused into the plasma. Despite the simplicity of the model, predicted fluorescence signals reproduce major features of the experimental data
Ultracold neutral plasmas (UNPs) are created in a vacuum by photoionizing laser-cooled atoms. The expansion of UNPs begins as a non-equilibrium system that quickly relaxes to a local equilibrium state [1] . We aim to quantify and compare the transport processes that govern the relaxation to equilibrium in the expanding UNP. Using a 1D-1V kinetic code in spherical coordinates, we model the radial expansion of an UNP. We compare our simulation results against analytic expressions to determine where the expansion of the UNP is adiabatic or isothermal. We carry out simulations for various initial density distributions such as an exponentially decaying density distribution [2] . We ultimately aim to extend this approach to a 1D-3V multi-component kinetic code that incudes collisions [3] .
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.
We report on the self-induced electron trapping occurring in an ultracold neutral plasma that is set to expand freely. At the early stages of the plasma, the ions are not thermalized which follow a Gaussian spatial profile, providing the trapping to the coldest electrons. In the present work, we provide a theoretical model describing the electrostatic potential and perform molecular dynamics simulations to validate our findings. We show that in the strong confinement regime, the plasma potential is of a Thomas-Fermi type, similar to the case of heavy atomic species. The numerically simulated spatial profiles of the particles corroborate this claim. We also extract the electron temperature and coupling parameter from the simulation, so the duration of the transient Thomas-Fermi is obtained.