569 / 2019-03-20 18:22:19

Two plasmon decay by lasers with large incidence angles

Direct drive ignition; Two-plasmon decay, Double beam, Oblique incidence

全体主题 > Laser and Particle Beam Fusion

In direct-drive laser fusion, two-plasmon decay (TPD) is a significant concern as a hot electron source due to its low threshold. We find that when laser incident plasma in a direction close to 60 degrees with the density gradient, its threshold can be largely reduced. In this situation, the turning-point density can be lower than the quarter-critical density thus TPD can be excited near where the laser gets reflected. PIC simulation show that significant amount of hot electrons can be generated. In addition, when two laser beams with large angles in between, the weak oblique laser can trigger TPD even though the normal-incident laser’s intensity is below its threshold. This may increase the preheating risk in direct drive ignition.