Optical probing of relativistic plasma singularities

Abstract

Singularities in multi-stream flows of relativistic plasmas can efficiently produce coherent highfrequency radiation, as exemplified in the concepts of the Relativistic Flying Mirror [S. V. Bulanov, et al., Phys. Rev. Lett. 91, 085001 (2003)] and Burst Intensification by Singularity Emitting Radiation (BISER) [Pirozhkov, et al., Scientific Reports 7, 17968 (2017)]. Direct observation of these singularities is challenging due to their extreme sharpness (tens of nanometers), relativistic velocity, and transient nonlocal nature. We propose to use an ultrafast (a few light cycles) optical probe for identifying relativistic plasma singularities. Our Particle-in-Cell (PIC) simulations show that this diagnostic is feasible.

Enhanced diagnostics of radiating relativistic singularities and BISER by nonlinear post-compression of optical probe pulse

“…The spectrum and the temporal shape of the initial and compressed pulses are plotted in figure 4 (a,b). As was shown earlier in [14], such duration is appropriate for probing of singularities emitting BISER radiation.…”

“…Multiple application of such mirrors leads to a decrease in the compression efficiency and to the appearance of pre-and post-pulses. Calculations show that, on several reflections from such mirrors, pulse compression, whose spectrum and spectral phase correspond to the implementation of 15.1 mJ/cm 2 (figure 3), makes it possible to achieve a duration of more than 20 fs, which is considered insufficient for qualitative observation of singularities [14]. Therefore, for achieving the required probing pulse duration in the given configuration of the experimental scheme, it is necessary to optimize the parameters of the medium, the fluence, and the number of reflections from chirped mirrors.…”

“…In the work [14] it was proposed to investigate plasma singularities during BISER by the Schlieren method. It was shown that in this case satisfactory resolution may be attained by using a probe pulse with a duration of a few optical field oscillations.…”

Numerical Studies on Bow Waves in Intense Laser-Plasma Interaction

“…Te electron beam accelerated by the wakefeld can generate ultra-short pulses and high-order harmonics [14,15]. Moreover, high-frequency pulses [16] and self-generated magnetic feld can be generated by using ultra-fast electrons to refect the probe light [17].…”

Ultra-strong attosecond laser focus produced by a relativistic-flying parabolic mirror

“…The RFM is a high-density electron layer and a part of the plasma cavity formed behind a propagating laser pulse. The physical properties of a laser pulse reflected by the RFM can be found in recent publications [2][3][4][5][6][7]. The RFM formed in the plasma cavity can be understood as a relativistic-flying parabolic mirror (RFPM) due to its paraboloidal shape.…”