Mitigating the hosing instability in relativistic laser-plasma interactions

Abstract

A new physical model of the hosing instability that includes relativistic laser pulses and moderate densities is presented and derives the density dependence of the hosing equation. This is tested against two-dimensional particle-in-cell simulations. These simulations further examine the feasibility of using multiple pulses to mitigate the hosing instability in a Nd:glass-type parameter space. An examination of the effects of planar versus cylindrical exponential density gradients on the hosing instability is also presented. The results show that strongly relativistic pulses and more planar geometries are capable of mitigating the hosing instability which is in line with the predictions of the physical model.

Channel optimization of high-intensity laser beams in millimeter-scale plasmas

“…e FLASH simulations predict that this will be true for Z 1 mm as can be seen in Figure 2(a), though the AFR ts suggest that this may be closer to Z 0.11 mm which would then cover the entire interaction region. In a signi cantly underdense plasma, the channel depth is determined by the number of particles with which the beam has interacted [32]. Because the density is greater in the cold plasma, it is appropriate that the channel would not have penetrated as deeply.…”

“…is lends support to the whole-beam selffocusing scheme referenced in the introduction. e pulses focused at a high density had a larger spot size as they propagated through the plasma, and thus they were more susceptible to lamentation [34] while interacting with more particles, leading to earlier pulse depletion [32].…”

“…sity will increase by a factor of the self-focusing ratio, R ≡ w 0 /w > 1, in 3D compared to 2D. According to the physical models present in the literature, the holeboring depth is given by [32,45]:…”

“…However, several instabilities occur during the pulse's travel-time which may erode the quality of the resulting channel. Perhaps most notable are the lamentation [25][26][27][28][29] and hosing instabilities [30][31][32] which together cause the pulse to bifurcate and alter its propagation direction. By doing so, the electromagnetic energy in any given beamlet is reduced and the resulting fast particles or photons in these schemes will be misdirected.…”

Advantages to a diverging Raman amplifier

“…High energy picosecond pulses, ideally in the ultra-violet, also have implications in inertial confinement fusion. The fast particle beams generated by these short pulses would provide auxiliary heating to the fusion fuel, either through collisional stopping 6,7 or two beam instabilities [8][9][10] . Since damage thresholds of solid state devices decrease in the ultra-violet range, ionised compression or gain media will be required.…”