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See full abstract here:
http://ocs.ciemat.es/EPS2019ABS/pdf/P2.3012.pdf
The kinetic effects on the dust particles observed in a plasma crystal locally irradiated by a narrow pulsed electron beam with energy 12 and 13 keV and peak current 4 mA are presented [1]. We observe in the top layer of the plasma crystal the formation of a stable dust flow along the irradiation direction in the first hundred milliseconds of the interaction. The spatial velocity profile of the dust flow can be well fitted with the sum of two Gaussian curves, one representing the velocity spread of the core stream due to the dust being pushed by the electron beam and the second being a measure of the kinetic energy deposited into the flow edge. The dust flow eventually becomes perturbed later in time, with the dust particles having chaotic trajectories as they are still drifting in the beam direction. The speed of the dust flow is mapped in a horizontal plane using the particle image velocimetry technique (PIV) [2]. A strong transversal heating of the dust particles takes place at the impact of the beam with the plasma crystal. At 13 keV the heating wave propagates rapidly sideways from the impact zone with a speed between 66 ± 2 mm/s and 81 ± 5 mm/s. It appears that in a transversal direction the kinetic energy decays exponentially with distance, with a decaying rate given by L-1, where L= 6.3-7.1 mm. The rich complexity of kinetics effects observed in the experiment presented here recommends the ensemble electron beam-plasma crystal as a suitable system for studying strongly coupled charged flows at convenient spatiotemporal scales.
[1] C.M. Ticos, D. Ticos and J.D. Williams (unpublished). [2] J.D. Williams, J. Plasma Phys. 82, 615820302 (2016).
