Abstract
The interaction of two energetic electron bunches generated in the wakefields of two intense intersecting laser pulses in rarefied plasmas is investigated using particleincell simulations. It is found that, with suitable intersection angle between the two laser pulses, the initially independent wakefield accelerated electron bunches can merged into a single one with high charge, energy, and narrow energy spread. The dynamics of the laserpulse intersection and wakebubble merging process is also investigated, and the crucial roles of the intersection angle are pointed out and analyzed.
This work was supported by the National Natural Science Foundation of China under the Grant No. 10835003 and was also supported by the National High Technology Research and Development Program of China.
I. INTRODUCTION
II. MERGING OF TWO ELECTRON BUNCHES
III. DYNAMICS OF ELECTRON MERGING
IV. EFFECT OF INTERLASER ANGLE
V. DISCUSSION AND CONCLUSION
Key Topics
 Carrier generation
 9.0
 Particleincell method
 8.0
 Electron beams
 4.0
 Electric fields
 3.0
 Laser plasma interactions
 3.0
H05H9/00
Figures
Schematic of the interaction of two nonaligned intense laser pulses with a rarefied plasma. The two pulses are identical except in the polarization. They are lunched into the simulation box from the left boundary with an interlaser angle and separation distance d.
Schematic of the interaction of two nonaligned intense laser pulses with a rarefied plasma. The two pulses are identical except in the polarization. They are lunched into the simulation box from the left boundary with an interlaser angle and separation distance d.
For , the electron density at (a) t = 40, (b) t = 65, (c) t = 150, and (d) t = 300.
For , the electron density at (a) t = 40, (b) t = 65, (c) t = 150, and (d) t = 300.
Properties of the energetic electrons (of energy ) for the merged electron bunch at t = 150. As reference, the properties of the energetic electrons generated by a single laser pulse along the xaxis at the same time are also shown. (a) Energy spectra. Inset: the divergence angle. (c) Charge distribution in the longitudinal direction.
Properties of the energetic electrons (of energy ) for the merged electron bunch at t = 150. As reference, the properties of the energetic electrons generated by a single laser pulse along the xaxis at the same time are also shown. (a) Energy spectra. Inset: the divergence angle. (c) Charge distribution in the longitudinal direction.
The merging process of the two groups of energetic electrons depicted in the phase space . p_{y} is normalized by , with m_{e} the electron mass and c the light speed. Electrons are colored according to the laser pulses. The snapshot of the energetic electrons at t = 65 (a) and t = 150 (b). The trajectories of two energetic electrons plotted in the real space (c) and in the phase space (d).
The merging process of the two groups of energetic electrons depicted in the phase space . p_{y} is normalized by , with m_{e} the electron mass and c the light speed. Electrons are colored according to the laser pulses. The snapshot of the energetic electrons at t = 65 (a) and t = 150 (b). The trajectories of two energetic electrons plotted in the real space (c) and in the phase space (d).
(a) Distribution of the effective focusing field F_{y} at t = 150. (b) Evolution of . F_{y} is normalized by , with ω the laser frequency and e the electron charge.
(a) Distribution of the effective focusing field F_{y} at t = 150. (b) Evolution of . F_{y} is normalized by , with ω the laser frequency and e the electron charge.
Effect of the interlaser angle θ on the merging process of the electron bunches. (a) Variation of the maximumdensity distance, D_{MD} , as a function of t for , 0.09, and 0.15. (b) The variation of the averaged transverse position, Y_{AP} , as a function of t for and 0.15. For comparison, the variation of Y_{AP} for the case of a singlelaser propagating along the axis is also given.
Effect of the interlaser angle θ on the merging process of the electron bunches. (a) Variation of the maximumdensity distance, D_{MD} , as a function of t for , 0.09, and 0.15. (b) The variation of the averaged transverse position, Y_{AP} , as a function of t for and 0.15. For comparison, the variation of Y_{AP} for the case of a singlelaser propagating along the axis is also given.
By 3D PIC simulations, the energetic electron density at t = 100 shown in (a) the (x, y) plane, (b) the (x, z) plane, and (c) the (y, z) plane.
By 3D PIC simulations, the energetic electron density at t = 100 shown in (a) the (x, y) plane, (b) the (x, z) plane, and (c) the (y, z) plane.
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