Laser Radiation Implosions
There has been much interest in the use of large lasers to ignite small amounts of fusion material. This process is known as inertial confinement fusion (ICF). As part of that research, much information on radiation implosion technology has been declassified.
When using optical lasers, there is a distinction made between "direct drive" and "indirect drive" systems. In a direct drive system, the laser beam(s) are directed onto the target, and the rise time of the laser system determines what kind of compression profile will be achieved.
In an indirect drive system, the target is surrounded by a shell (called a Hohlraum) of some intermediate-Z material, such as selenium. The laser heats this shell to a temperature such that it emits x-rays, and these x-rays are then transported onto the fusion target. Indirect drive has various advantages, including better control over the spectrum of the radiation, smaller system size (the secondary radiation typically has a wavelength 100 times smaller than the driver laser), and more precise control over the compression profile.
Read more about this topic: Radiation Implosion
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