Interaction of parametric instabilities from 3ω and 2ω lasers in large-scale inhomogeneous plasmas

Abstract

The mechanism of energy transfer from 3ω pump light to stimulated Brillouin scattering (SBS) generated by 2ω pump light is proposed. The backscattering light of stimulated Raman scattering (SRS) generated by 3ω pump light can work as a seed of the SBS of 2ω pump light, which results in the increase of the latter. Adding 2ω pump light into 3ω pump light will decrease the reflectivity of SBS generated from 3ω pump light. The total reflectivity will first decrease and then increase with an increase of the ratio of 2ω light intensity to the intensity of 2ω and 3ω lights f = I 2ω0 /(I 2ω0 + I 3ω0 ), and will be controlled in a lower level when this ratio f is about 10%−20%. These results give a method to control the total reflectivity of SBS and SRS in inertial confinement fusion (ICF) by adding 2ω light into 3ω light.

Stimulated Brillouin scattering enhanced by the stimulated Raman process near the quarter-critical density

“…The second harmonic can serve as a seed to induce SBS in the low-density region, then resulting in a much higher reflectivity of SBS. The interactions between SRS and SBS are widely studied, such as the SBS of SRS light [33], and the energy transfer from 3ω pump light to SBS generated by 2ω pump light [34]. Here we attempt to study the new interaction: SBS can be enhanced by the second harmonic of SRS light.…”

Suprathermal electrons from the anti-Stokes Langmuir decay instability cascade

“…However, in high-Z plasmas such as Au plasmas, the collisional damping is even stronger than the Landau damping of ion-acoustic waves. The research of parametric instabilities in different ion-species homogeneous [54] and inhomogeneous plasmas [53] were investigated in detail by Feng et al…”

“…The 1D and 3D Particle-in-Cell (PIC) code EPOCH [52,53] was used to investigate the hot electron generation mechanisms from the different instabilities to confirm the 045208-13 veracity of the results in Sec. II when extrapolated to higher dimensions (this was not possible with the Vlasov code due to the available computational resources).…”

Suppression of stimulated Brillouin and Raman scatterings using an alternating frequency laser and transverse magnetic fields

“…[26] All these methods or combinations of them have been widely used to control the peak intensities of laser spatial speckles and hence to suppress instabilities in ICF, but they cannot reduce LPIs to a tolerable level. [27,28] Recently, some new theoretical schemes for suppressing LPIs by changing lasers have also been proposed, including various broadband technologies, [29][30][31][32] two-color incident light, [33][34][35] spike trains of uneven duration and delay (STUD), [36][37][38][39] rotating polarization, [40][41][42] alternating polarization, [43,44] the discretely changing phase, [45] etc. It can be seen that in order to reduce the development of LPIs, existing schemes focus on changing the laser frequency, amplitude, polarization direction and phase.…”