Inertial Confinement Fusion
The fuel pellet, or target, is compressed and heated with what are called energy drivers. These high-powered sources of energy are usually either high-powered laser or ion beams, which bombard the target from all sides symmetrically. The outer layer of the pellet vaporizes and moves away from the pellet like a rocket. This projection creates shock waves which go on to compress and heat the core. The compressed fuel then burns, releasing much energy, and expands. This is partially offset by the shock waves, which tend to continue compressing the material. This behavior is known as inertia. The result is an inertal confinement fusion reaction.
Direct and Indirect Drive Fusion Ignition
There are two types of targets: a direct-drive inertial fusion energy target, and an indirect one. The direct-drive targets are just the spherical pellets containing the fuel (most likely a mix of dueterium and tritium) which will be pounded directly by a laser or ion beam. The indirect-drive targets have the fuel pellet placed inside a hohlraum, which is a small and thin cylindrical container composed of a high atomic number material, like gold or lead. The container will convert the driver beams into x-rays, which subsequently compresses the fuel.
The image to the right is a reperesentation of indirect-drive using a hohlraum. The blue objects in the image are beams entering the hohlraum. The dime is there to show the relative size of the hohlraum used.
Another Promising Advance - The Fast IgnitorThe fast ignitor is a variation on the standard inertial confinement methods. The difference is that an extremely short and intense laser creates a hotspot in the center of the fuel which ignites the core. There are four steps in this process:
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