Shock Ignition in Indirect Drive

Shock ignition is an approach to ignition and thermonuclear burn in ICF that has the potential to produce higher fusion energy gains at lower laser drive energies compared with conventional central hotspot ignition. However, to date it has only been considered generally feasible in laser direct drive. Here, we present preliminary research that might permit shock ignition to be obtained in indirect drive in a hohlraum. Our conventional indirect drive ignition platform on NIF uses a single laser pulse shape to compress and ignite a thin shell of fusion fuel at high velocity. By contrast, here we assemble a thick, low velocity shell in indirect drive in 3w blue light that is then separately ignited by a strong shock driven by a subset of the NIF beams in 2w green light. By decoupling the compression from the ignition, significantly more fuel mass can be assembled and ignited, resulting in higher fusion yields/gains relative to conventional targets. Moreover, the thick, low-aspect-ratio shells may be less affected by symmetry and stability perturbations. A central issue will be LPI driven by the high intensity shock pulse. Compared to other advanced ICF ignition concepts, not only could this be testable on NIF with present day hardware (in all-blue light) or near-term hardware (mixed blue/green light) but, being indirect drive, its knowledge base is underpinned by the extensive experimental database of the NIF ignition program