When
an intense laser pulse interacts with a solid, liquid or gas, it very
quickly drives it into the fourth state of matter; plasma. A plasma is
formed when electrons are released from their host atoms in the presence
of the extremely high electric fields of the laser, generating a
gaseous soup of subatomic particles consisting of ions and electrons.
All
types of radiation are given off during a high power laser-plasma
interaction, including beams of electrons, protons, ions, X-rays, gamma
rays and neutrons. The radiation is sampled using various diagnostics in
the target chamber, which can you give you information about the
interaction, such as the plasma temperature. The laser-plasma only
exists for the briefest of times, much less than a billionth of a
second, but a lot of very interesting and useful physics can go on in
that time.
Why are we interested in high power lasers?