High power lasers focussed onto solid or sometimes gaseous targets are used to produce plasmas. These plasmas rapidly expand, but interesting high density states of matter are briefly produced (see, for example, the discussion on warm dense plasmas below). Laser-plasmas are sources for high energy particles (electrons and ions) and bright emitters of x-ray and extreme ultra-violet (EUV) light. The high density plasmas produced by laser irradiation can be used to simulate astrophysical plasma expansion and to understand plasma properties (such as opacity). Researchers in the Department are investigating these and other aspects of laser-produced plasmas.