The comeback of shock waves in inertial fusion energy

The shock waves in laser plasma interaction have played an important role in the study of inertial fusion energy (IFE) since the 1970's and perhaps earlier. The interaction of laser, or any other high power beam, induced shock waves with matter was one of the foundations of the target design in IFE. Even the importance of shock wave collision was studied and its importance forgotten. In due course, the shock waves were taken as granted and became "second fiddle" in IFE scenario. The analysis of the shock wave in the context of IFE is revived in this paper. At the forefront of the past decade the concept of fast ignition was introduced. The different ideas of fast ignition are summarized with special emphasis on shock wave fast ignition. The ignition is achieved by launching a shock wave during the final stages of the implosion. In this paper, a possible instability in the propagation of the igniting shock wave is analyzed. The idea of combining the fast ignition fusion with an impact shock wave is suggested and analyzed. This is achieved by launching a shock wave by an accelerated foil during the final stage of the implosion in order to ignite the compressed fuel. In this scheme, like other fast ignition schemes, a significant reduction of the driver energy in comparison with standard IFE scenarios is required for the same high gain fusion.