The effect of laser intensity distribution along the line focus on the uniformity of the line-shaped plasmas produced is investigated with time-integrated and time-resolved soft X-ray and optical diagnostics. Evident plasma condition nonuniformities along the line focus resulting from nonuniform laser intensity distributions have been observed with a conventional simple line-focusing technique. With a new line-focusing technique producing a uniform laser illumination, a uniform, line-shaped plasma can be obtained. It is also found that nonuniformities under uniform laser illumination occur mostly during laser heating. The line-shaped uniform laser plasma can be used as a large, uniform X-ray source besides its importance in X-ray laser demonstration and amplification. As an application of such line-shaped plasmas as X-ray sources, the no-overcoat 5F X-ray film is calibrated for the first time by a new method in the soft X-ray range from 10–80 A.
Laser plasma interaction in copper nano-particle targets