PPPS-2013: Optimal control of laser-plasma instabilities using spike trains of uneven duration and delay (STUD pulses)

摘要

We show new results on the effectiveness of STUD pulses to control, in an adaptive manner, fast or slow parametric instabilities in laser-plasma interactions¹. Fluid simulations² and statistical optical theory are used to show how Stimulated Brillouin Scattering (SBS) can be suppressed in inhomogeneous flowing plasmas in the strong ion-wave damping regime with structured laser beams. When STUD pulses are being tailored to the evolution of the instability to be controlled, a number of key pulse shaping ingredients must be varied to optimize the fit. Chief among these is the modulation period, the duty cycle and the spatial scrambling rate of the pump laser's space-time evolution profile. We will show that for a probe beam, which is also composed of fast STUD pulse modulations, steady state behavior of drastically reduced instability levels is possible with the proper adaptive targetting of the pump STUD pulse profile. Nothing need be known about the plasma conditions a priori in order to execute this plan. It is believed that future lasers for high intensity laser-matter interactions and laser-fusion where instabilities are expected to be controlled and steered, STUD pulses offer a very attractive path forward. Current ambiguities and disasters in such high intensity inertial confinement fusion (ICF) settings could be a thing of the past with the implementation of these ultra-fast optics inspired pulse shaping techniques. Statistical, nonlinear and ultrafast optics are the three major ingredients necessary to execute this plan. These will be amply demonstrated.