A major source of energy loss in laser-driven fusion could be remedied with the use of optical elements called zooming-phase plates.
For several decades, researchers have been using the world’s most powerful lasers to try to recreate the fusion reaction that occurs in stars. The process, called inertial confinement fusion (ICF), uses multiple laser beams to compress and heat a small, spherical target containing nuclear fuel, in order to ignite thermonuclear fusion. In principle, the heat released from the reaction could provide an alternative energy source, but the challenges to achieving ignition are many. One, in particular, is to understand and control a process first identified in the mid-1990s [1] called crossed-beam energy transfer (CBET), in which the laser beams exchange energy with each other as they overlap in the plasma. In laser-driven fusion experiments, CBET occurs just before the laser beams deposit their energy into the target. The effect can therefore modify the finely tuned symmetry of the beams [2, 3] or cause energy to leak out of the target [4, 5].
Now, Igor Igumenshchev from the Laboratory for Laser Energetics at the University of Rochester in New York and colleagues are proposing a new technique to mitigate the negative effects of CBET. In Physical Review Letters, Igumenshchev et al. use simulations to show that dynamically reducing—or “zooming”—the spot size of the lasers as they interact with the target would reduce energy transfer between the beams, without disrupting the symmetry of the laser illumination [6]—a negative side effect of some existing proposals for correcting CBET.
To read more, click here.