Typically, 70-80% of the laser energy can be converted to x-rays. This energy causes the fuel capsule to implode. Laser beams enter the hohlraum through holes in the end caps, heat the walls of the cylinder, which then radiate soft x-rays, filling the hohlraum with a bath of radiant energy.
With indirect drive, the capsule is positioned in the center of a cylindrically symmetric container called a hohlraum. With direct drive, this uniform heating of the capsule is caused by simultaneously illuminating the capsule from all sides with many laser beams and taking great care (via beam conditioning to avoid speckle etc.) to assure that 2 points close to one another on the capsule surface are driven with the same illumination. The capsule must not only be driven hard, but also uniformly over its entire surface to cause uniform compression of the fuel to the center.
That shell surrounds a hot spot of fuel with sufficient temperature (roughly 10 keV or 100 million degrees) to ignite a fusion reaction. When the shell and its contained fuel stagnates upon itself at the culmination of the implosion, most of the fuel is in a compressed shell which is at 1000 times solid density. = cgs]), generating an acceleration of the shell of about 10 trillion gees, and causing that shell to reach, over the course of a few nanoseconds, an implosion velocities of 300 km/sec.
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