NIF(National Ignition Facility at the Lawrence Livermore National Laboratory in California) uses the ICF (inertial confinement fusion) approach in order to harvest fusion energy.
At NIF, indirect drive laser ICF uses a "hohlraum" which is irradiated with a laser beam to bathe a peppercorn - sized fusion capsule inside with smooth high intensity X-rays. The capsule contains hydrogen fuel (actually its isotopes, deuterium and tritium), and when compressed, it creates a hot, dense ball 1/60000 th its original volume. Inside this tiny sphere, a cascade of fusion reactions would release many times more energy than the laser delivered. The newly formed helium would not be able to escape easily, and the heat generated from these extra collisions would encourage more hydrogen to fuse. Fusion would briefly become self-sustained leading to a huge jump in the energy produced (at least in principle).
The problem is maintaining the symmetry of the implosion. Once the capsule begins to collapse, instead of remaining spherical, as the simulations predicted, the capsule warps into an amorphous blob. Little bumps emerge on its surface, and these imperfections grow exponentially. The highest energy output achieved (according to a report in December 2012) was at most a third of the amount needed to trigger the helium collisions that would ignite the fuel.
A possible solution. Instead of using plastic coated fuel capsules, why not use capsules made of deuterium saturated palladium? The crystal structure of the hydrogen palladium system would represent a multitude of deuterium microcapsules embedded in the crustal structure of palladium. At implosion, the Coulomb repulsion would be easily overcome, due to the imploding crystal structure of the palladium. Not to be discouraged here that deuterium saturated palladium was considered by Pons and Fleischmann in their cold fusion experiments, proved to be misleading (in their case, fusion was not a factor). It has nothing to do with that , but the deuterium saturated palladium capsules could be feasible for ICF.