High-aspect-ratio line focus and plasma production using a random phase plate

Abstract
The use of rectangular-element random phase plates to generate a line focus is described. Photographic records of the resultant focus are presented and compared with theoretical calculations made by using an interference code. Good agreement is found. The code is used to investigate possible design modifications to produce a more square-topped line focus. A 12-ps Raman-shifted KrF (λ = 0.268 μm) laser pulse is used in combination with such plates to produce a laser plasma. The plasma conditions are extensively characterized by using time-resolved extreme UV spectroscopy and a pinhole camera, and their suitability for x-ray laser applications is discussed.