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Electron acceleration is investigated in a plasma wake generated via the interaction of a high-intensity laser pulse with the plasma in the presence of a perpendicular magnetic field. For this purpose, using the Maxwell equation, the wakefield profile in the perpendicularly magnetized plasma is obtained and then using the magnetized wakefied the electron energy and momentum equations are numerically solved. It turns out that the electron acceleration in a magnetized wake having a different profile than unmagnetized one increases with the perpendicular magnetic field strength so that in presence of a magnetic field with a strong enough amplitude the acceleration goes beyond the resonance regime. The numerical results demonstrate that the electron could be significantly accelerated in a low-amplitude laser-driven wake in presence of an external perpendicular magnetic field which can be superseded the high-amplitude laser-driven wake acceleration regime. Furthermore, we concluded in such systems that the electron acceleration is drastically sensitive to amplitude and initial phase of the wakefield as well as the initial energy of the electron. [ABSTRACT FROM AUTHOR]

High-field Terahertz (THz) with a broad frequency spectrum has important application in THz optics and imaging. In this paper we report a way for generating THz fields, which uses an electron beam propagating opposite to the laser pulse. The laser excites wakefields via charge separation associate with the ponderomotive force. The laser wakefield couples with the negative energy electron beam to drive the THz electromagnetic mode. The applied magnetic field provides an additional resonance to this parametric interaction between the laser and electron beam. The THz fields of 20 GV/cm with spectrum band covering the range from 1 to 15 THz can be realized. Several scaling laws are provided to optimize the THz fields. This work provides a reasonable approach to generate THz radiation fields during intense laser-plasma interactions. [ABSTRACT FROM AUTHOR]

The brightness of betatron radiation generated by laser wakefield accelerated electrons can be increased by utilizing the laser driver with shorter duration at the same energy. Such shortening is possible by pulse compression after its nonlinear self-phase modulation in a thin plate. However, this method can lead to a rather complex femtosecond-scale time structure of the pulse. In this work, the results of numerical simulations show that the presence of prepulses containing a few percent of the main pulse energy can significantly alter the acceleration process and lead to either lower or higher energies of accelerated electrons and generated photons, depending on the prepulse parameters. Simultaneously, the presence of a pedestal inhibits the acceleration process lowering the brightness of the betatron source. Furthermore, postpulses following the main pulse are not found to have a significant effect on betatron radiation. [ABSTRACT FROM AUTHOR]

The effects of super-Gaussian chirped laser pulse and inhomogeneity of plasma on space distribution and amplitude of wakefield are studied. The different super-Gaussian chirped laser pulse envelopes are used to strike the uniform and various inhomogeneous plasmas. The results show that compared with the unchirped laser pulse, the chirped laser pulse can enhance the wakefield generation, make the bubbles’ structure deformative seriously, reduce the numbers of bubbles in the same longitudinal distance, and enlarge the size of the wakefield bubbles. Besides, the stronger wakefield is generated in inhomogeneous plasma compared with a uniform one. Moreover, the characteristics of the wakefield can be controlled efficiently by the super-Gaussian pulse index. That is, the amplitude and spatial structure of the plasma wakefield can be modulated by the super-Gaussian chirped laser pulse and the inhomogeneity of the plasma. [ABSTRACT FROM AUTHOR]