The laser pulse, that propagates from left to right, drives a strong wake with relativistic curved front. Reprinted with permission from Ref. 15.
The laser pulse that propagates from left to right, expels electrons on his path, forming a positively charged cavity. The radially expelled electrons flow along the cavity boundary and collide at the bubble base, before being accelerated behind the laser pulse.
Electron beam distribution for different plasma densities showing the transition from the self modulated laser wakefield and the forced laser wakefield to the bubble/blow-out regime. From top to bottom, the plasma density values are , and .
Top: The target schematic representation with embedded supersonic gas jet into a capillary that is filled with hydrogen gas, Bottom: the charge (squares), energy (circles), and energy spread (triangles) as a function of the peak jet density. Reprinted with permission from Ref. 54.
A few shots representative for those 10% of all the shots with lowest energy spread for self-injection (top) and injection at a density transition (bottom). The horizontal axis in each image corresponds to the transverse electron beam size; the vertical axis shows electron energy. Reprinted with permission from Schmid et al., Phys. Rev. ST Accel. Beams 13, 091301 (2010). Copyright © 2010 by the American Physical Society.
Scheme of principle of the injection with colliding laser pulses: (a) the two laser pulses propagate in opposite direction, (b) during the collision, some electrons get enough longitudinal momentum to be trapped by the relativistic plasma wave driven by the pump beam, and (c) trapped electrons are then accelerated in the wake of the pump laser pulse.
(a) Evolution of the electron beam peak energy and its energy spread as a function of the collision position for two parallel polarized laser beams. The electron beam peak energy is shown in red, and the energy spread in blue. Each point is an average over 35 shots and the error bars correspond to the standard deviation. The position corresponds to injection at the middle of the gas jet, whereas corresponds to early injection close to the entrance of the gas jet. Reprinted with permission from Ref. 58. (b) Evolution of charge (red solid line with squares), at FWHM (blue dotted line with circles) with the angle between the polarizations of injection and pump lasers (, parallel polarizations; , crossed polarizations). Parameters are , 3 mm gas jet, . (c) Deconvolved spectra with a high resolution spectrometer measurement.Physical parameters: , 3 mm gas jet, . Reprinted with permission from Rechatin et al., Phys. Rev. Lett. 102, 164801 (2009). Copyright © 2009 by the American Physical Society.
Longitudinal electric field computed at t = 43 fs in 1D PIC simulation (solid red line), and in fluid simulations (dotted blue line). The transverse electric field is also represented (thin dotted line). The laser pulse duration is 30 fs FWHM, the wavelength is 0.8 m, , and . The laser pulses propagate in a plasma with electron density . In (a), the case of parallel polarization and in (b) the case of crossed polarization.
Normalized longitudinal electric field (continuous line). (a) The laser (dotted line) wakefield. (b) The electron bunch (dashed line) wakefield. (c) Field resulting from the superposition of the laser and electron beam wakefields. The normalized vector potential is , the laser pulse duration is 30 fs, , the bunch duration is 10 fs and its diameter is 4 m. Reprinted with permission from Rechatin, Ph.D. thesis.
(a) Schematic of the experimental setup showing the laser beam, the two-stages gas cell, on left the injector part and on right the accelerator part. (b) Magnetically dispersed electron beam images from a 4 mm injector-only gas cell (top) and the 8 mm two-stages cell (bottom). Reprinted with permission from Pollock et al., Phys. Rev. Lett. 107, 045001 (2011). Copyright © 2011 by the American Physical Society.
(a) Principle of the injection by colliding laser pulses: in the “hot” injection scheme, injection is achieved thanks to momentum (red/continuous arrow) gained by electrons from the plasma wave (green/dashed curve) during the collision, which allows them to cross the separatrix (blue/continuous curve). Injection principle in the cold injection scheme: electrons are injected by being dephased from the front of the main pulse to its back without momentum gain (balck/dashed arrow). After dephasing, electrons are efficiently injected over the separatrix. (b) Principle of electron dephasing in a standing wave (dotted line) generated by the collision between two counter-propagating circular laser pulses. Reprinted with permission from Davoine et al., New J. Phys. 12, 095010 (2010). Copyright © 2010 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft.
Article metrics loading...
Full text loading...