Ultrafast lasers and nuclear fusion
Tue Jul 25 21:44:39 BST 2006
Things that we can do now that we could not five years ago: create attosecond pulses of coherent X-rays. We can do this by hitting a gas with a very short (femtoseconds long), very intense laser (terrawatt peak power) pulses. The underlying physics is multiphoton acceleration of the electrons in the atoms of the gas - the laser is intense enough that the potential seen by the electron changes on the timescale of the electron's vibration in the atom, so resonant forcing occurs.
How does this relate to fusion? One approach to fusion is to hit the fusion pellet fast enough and with enough energy that [inertial confinement] occurs. This means that the energy has no time to be distributed over the entire pellet, but instead is concentrated in the area where the laser pulse hits. This region turns into a plasma and the back reaction compresses and heats the pellet enough that fusion occurs.
Here is the idea: take the attosecond pulse production setup and cause it to create a sphere of pulses around the central target. Use a holographic diffraction element to produce the desired intensity profile from a single beam for ease of synchronisation. The pulses will hit the central target and dump a large amount of energy into it in a short amount of time. Short enough for fusion?
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