Dynamical bunching and density peaks in expanding Coulomb clouds

Abstract

Expansion dynamics of single-species, non-neutral clouds, such as electron bunches used in ultrafast electron microscopy, show novel behavior due to high acceleration of particles in the cloud interior. This often leads to electron bunching and dynamical formation of a density shock in the outer regions of the bunch. We develop analytic fluid models to capture these effects, and the analytic predictions are validated by PIC and N-particle simulations. In the space-charge dominated regime, two and three dimensional systems with Gaussian initial densities show bunching and a strong shock response, while one dimensional systems do not; moreover these effects can be tuned using the initial particle density profile and velocity chirp.

16 pages, 6 figures(spread over 18 png files); No changes to the text --- however I had mis-spelled Chong-Yu Ruan's first name in the metadata. (It was originally Chung-Yu). This typo has been addressed

References in corpus (3)

• Radiation Pressure Dominate Regime of Relativistic Ion Acceleration
• Incompressible relativistic spheres: Electrically charged stars, compactness bounds, and quasiblack hole configurations
• Measurement of net electric charge and dipole moment of dust aggregates in a complex plasma

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• Rapid charge redistribution leading to core hollowing in a high-intensity ion beam
• Density shocks in the relativistic expansion of highly charged one component plasmas
• Longitudinal crossover and the dynamics of uniform electron ellipsoids focused by linear chirp
• Toward nonthermal control of excited quantum materials: framework and investigations by ultrafast electron scattering and imaging