Fig. 1. Section of generic high-gain laser fusion spherical target design.

Fig. 2. Predicted target energy gains versus incident laser energy for several designs. Shock-ignition gains are similar to fast-ignition target gains, and KrF lasers have superior performance due to their shorter laser wavelength and the ability to reduce the focal spot size to match the imploding target.

Fig. 3. Generic laser pulse shape for the shock-ignition target. The prepulse sets the initial radial adiabat. The main pulse compresses the cold fuel. The ignitor pulse produces the spark for ignition. The conventional direct-drive target pulse shape is similar except without the final ignitor pulse.

Fig. 4. Naval Research Laboratory’s electron beam pumped Electra KrF laser system. The laser output window is between the two black magnet coils in the center of the photo. The arrow shows the laser path. The magnets guide the electron beams into the laser gas. The pulsed power systems for the electron beams consist of the blue pulse forming lines and the two white tanks that flank the laser cell.

Table 1. Comparison of target performances for a shock-ignition target driven by the two types of laser, with the same ablation pressure, and similar fuel mass and thermonuclear yields. For the DPSSL, with its poorer laser–target coupling, the target energy gain drops significantly and the possible deleterious effects of laser–plasma instabilities increase significantly