Dynamics of moving electron vortices and magnetic ring in laser plasma interaction

Abstract

Moving electron vortices have been observed in laser interaction with non-uniform near-critical-density plasma by multi-dimensional Particle-in-Cell simulations. In two dimensional geometry there are two vortices with opposite magnetic polarity, moving perpendicularly to the plasma density gradient direction. The field distribution and particle motion composing such moving structure have been clearly observed in simulations, which explains the vortex motion. Two components of loop currents are formed around each electron vortex, which dominate the vortex motion. The moving velocity can be as large as 0.2c level, forming relativistic vortices inside the plasma. Laser plasma conditions such as intensity, polarization, density profile and external magnetic field effects on the vortex motion and evolution are also studied. In three dimensions, the structure appears as an expanding magnetic ring with an internal magnetic field up to 1000 Tesla. Such vortex structures suggest an interesting way of energy (with more than 5% of the laser energy) transportation to ambient plasmas as far as 50µm away from the laser-plasma interaction region, which may have applications in laser plasma based inertial confinement fusion and laboratory astrophysics.

Electrostatic shock waves driven by electron vortices in laser–plasma interactions

“…At the same time, it traps electrons from the low-density region, as shown in figure 2(d), to keep its rotating current, which supports the quasi-static electric and magnetic fields. The fields then drive the forward motion of the vortex [35]. In our simulation we find that for the first 400 T 0 period the vortex energy is linearly dissipated along the transverse direction and it can move to a distance about 100 µm.…”

“…The two EVs move perpendicular to the laser propagation direction with a velocity of V d ≈ 0.28c, as shown in figure 1(a), where c represents the light speed in vacuum. Such structures have been studied and reported in previous literature [26,34,35]. Here, we focus on the following process of vortex motion and its interaction with the ambient plasma.…”

“…One can see that the vortex and shock structures can exist in a wide range of laser-plasma parameters. The drift velocity of the vortex (V d ) is approximately proportional to the laser intensity (a 0 ) and the density gradient (−∇n e ) [34,35]. With higher laser intensity, the EVs contain more electromagnetic energy and can excite higher shock velocities.…”

Post-solitons and electron vortices generated by femtosecond intense laser interacting with uniform near-critical-density plasmas

“…[11,12] And high-order harmonic generation (i.e., laser-driven attosecond sources) can be applied in materials science and molecular biology. [6] For near-critical-density (NCD) plasmas, nonlinear physical processes or structures like stimulated Raman scattering (SRS), [13] post-solitons [7,14] and electron vortices [9,10,15,16] have also been studied. However, the symbiotic relationships of these structures have not been explored in detail.…”