Four-Frame UV/X-Ray Picoframe II Framing Camera

ABSTRACT Electron-optical framing cameras having X-ray/XUV photosensitivities and which can provide a sequence of framed images in the subnanosecond regime are of major relevance and importance to the quantitative monitoring of the kinetics of laser-produced plasmas. Our Picoframe family of framing cameras which has been developed comprise specially designed image tubes that permit the recording of single or multiple frames in the picosecond domain. For instance, an experimental UV-sensitive Picoframe I camera system has been demonstrated to have temporal and spatial resolution of 100 ps, 8 Ip/mm in single frame format and 250 ps, 8 Ip/mm in a double-frame format having an interframe period between 1.5 ns and 2ns.In this presentation we will describe a double-aperture Picoframe II version of this camera and details will be given in respect of the performance of a demountable, UV-sensitive system. Particular emphasis will be devoted to its operation in a four-frame image format where the generation and implementation of appropriate deflection voltage profiles are especially significant. Experimental data will be presented to show that four discrete frames can be recorded with a frame period of 230 ps, interframe time of ~1 ns and a dynamic spatial resolution (referred to the photocathode) of 7 Ip/mm. This spatial resolution was retained over the entire area of the 6 mm x 6 mm image geometry at the photocathode. Such a UV-sensitive camera can be readily adapted for operation in the soft X-ray spectral region, as previously reported for the Picoframe I counterpart, and some of the projected performance characteristics will be discussed.1. INTRODUCTIONWith the development of ultra-high power, short pulse lasers significant interest has been shown in their potential use to initiate fusion reactions in microballoon type deuterium-tritium filled targets. In order for the reaction to be efficient it is essential that the target be illuminated evenly on all sides in order to provide uniform compression and hence maintain confinement time. It is therefore important to study the two-dimensional evolution of X-ray self-emission of laser-produced plasmas with