Investigation of the potential for high gain, shock-ignition on the National Ignition Facility

Shock ignition, a new concept for igniting thermonuclear fuel, offers the potential for a near-term test of high gain inertial confinement fusion on the National Ignition Facility at less than 1MJ drive energy and without the need for new laser hardware. In shock ignition, compressed fusion fuel is separately ignited by a strong spherically-converging shock and, because capsule implosion velocities are significantly lower than those required for conventional hotpot ignition, simulations indicate that high fusion energy gains of ∼60 may be achievable on NIF at laser drive energies around ∼0.5 MJ, extending to ∼100 at 1 MJ. Because of the simple all- DT or DT/CH target designs, their in-flight robustness, the potential need for only 1D SSD beam smoothing, minimal early-time LPI preheat issues, and employment of day-1 laser hardware, these targets may be easier to field on NIF than a conventional (polar) direct drive hotspot ignition target. Like fast ignition, shock ignition has the potential for high fusion yields at low drive energy, but requires only a single laser with less demanding timing and spatial focusing requirements. Of course, conventional symmetry and stability constraints will apply, thus a key immediate step for shock ignition on NIF is to demonstrate the adequacy of low-mode uniformity and shock symmetry in the polar drive configuration. Shock ignition offers the prospects for high-gain targets that may lead to smaller, more economic fusion power reactors and a cheaper fusion energy development path.