Initial stages of hydrodynamic expansion of plasma heated by intense laser radiation

The hydrodynamic equations describing the average behavior of a one-dimensionally expanding plasma heated by laser radiation are solved analytically. For the small parameter approximation, the hydrodynamic expansion depends on the parameter (16P/9Ml02)1/3τL, where P is the laser power, M is the plasma mass, l0 is the initial plasma length, and τL is the laser pulse duration. With τL=τei, the electron ion relaxation time, it is possible to compute φmax (≈5.6×10−6n04l03miT−9/2, where mi is the plasma ion mass and T is the temperature), the maximum flux density below which the hydrodynamic expansion may be neglected. We find that a 5-kJ 75-ns neodymium glass laser is capable of acheiving break-even conditions for a 50% mixture of deuterium-tritium gas.