Ultra-intense attosecond pulses emitted from laser wakefields in non-uniform plasmas

Abstract

A scheme of generating ultra-intense attosecond pulses in ultra-relativistic laser interaction with under-dense plasmas is proposed. The attosecond pulse emission is caused by an oscillating transverse current sheet formed by an electron density spike composed of trapped electrons in the laser wakefield and the residual transverse momentum of electrons left behind the laser pulse when its front is strongly modulated. As soon as the attosecond pulse emerges, it tends to feed back to further enhance the transverse electron momentum and the transverse current. Consequently, the attosecond pulse is enhanced and developed into a few cycles later until the density spike is depleted out due to the pump laser depletion. To control the formation of the transverse current sheet, a non-uniform plasma slab with an up-ramp density profile in front of a uniform region is adopted, which enables one to obtain attosecond pulses with higher amplitudes than that in a uniform plasma slab.

Electromagnetic radiation from laser wakefields in underdense plasma

“…As shown in Figure 4(a), the field for is about 20 times that for . This is the regime which we have identified before [13, 14] . Likewise, the frequency spectrum differs significantly for the weakly relativistic, fully relativistic, and the wave-breaking regimes, as illustrated in Figure 4(b).…”

“…If one increases the plasma density and the laser intensity, the radiation shows up in the form of a pulse chain with frequency around the laser frequency. As the laser intensity is enhanced further, wake wave-breaking occurs and XUV radiation is emitted [13, 14] . A simple theoretical analysis is presented for the physical mechanisms involved.…”

Spectrum bandwidth narrowing of Thomson scattering X-rays with energy chirped electron beams from laser wakefield acceleration

“…For coherent sources, radiation based on high harmonics generation in laser-solid interaction or coherent Thomson scattering from laser nanometer electron sheet interaction are studied [9][10][11]. The latter has attracted more and more interests recently due to the feasibility of electron sheet generation resulting from laser plasma interactions [12][13][14].In this paper, we focus on incoherent radiation from laser electron Thomson scattering. We use the electron beam accelerated from a laser wakefield accelerator [15,16], which may allow easy synchronization between the electron beams and laser pulses.…”

“…For coherent sources, radiation based on high harmonics generation in laser-solid interaction or coherent Thomson scattering from laser nanometer electron sheet interaction are studied [9][10][11]. The latter has attracted more and more interests recently due to the feasibility of electron sheet generation resulting from laser plasma interactions [12][13][14].…”