In inertial confinement fusion, a small (~ 1 mm radius) capsule is imploded to reach the temperatures and densities needed for fusion. In the National Ignition Campaign (NIC), we are using the indirect drive approach to ignition. In indirect drive, the deuterium-tritium filled capsule is held inside a high Z can or hohlraum. The National Ignition Facilities (NIF) 192 laser beams are focused into this hohlraum, where the laser energy is converted to xrays, which drive the capsule. The NIF laser was dedicated in May 2009 and target physics experiments began in the summer of 2009. Since that time, we have been conducting experiments to tune the capsule for ignition. In order to achieve ignition, we need to tune the shape of the implosion, tune the series of four shocks to accelerate the shell while keeping it on a low adiabat, tune the laser pulse to achieve the required peak velocity, and control hydrodynamic mix of ablator material into the fuel. The campaign in the spring of 2011 focused on improving the adiabat of the fuel, which is needed to achieve adequate compression. These experiments led to an increase in the rho*r of the shell by more than 50%. The current campaign is focused on getting high velocity while maintaining good compression and shape. In this talk, we will discuss progress in each of these areas on the way to ignition and techniques used to model these experiments.
*This work was performed under the auspices of the U.S. Department of
Energy by Lawrence Livermore National Laboratory under Contract
DE-AC52-07NA27344.
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