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Ultrahigh-speed two-dimensional x-ray imaging by using an image sampling technique on an x-ray streak camera has been developed and applied to observe the imploded core plasmas of inertial confinement fusion targets. Various one-dimensional and two-dimensional sampling techniques of two-dimensional images were compared, and the multi-imaging x-ray streak camera (MIXS), was found to be one of the most successful schemes. MIXS was used in an implosion experiment of a shell target with a cone for fast ignition at the OMEGA laser facility. Nonuniform structure in imploded core plasma dynamics was clearly observed with temporal and spatial resolutions of 10 ps and 10-20 μm, respectively. [ABSTRACT FROM AUTHOR]

A time-resolved pinhole camera is being developed for monochromatic soft x-ray imaging of z-pinch plasmas on the Z accelerator [R. B. Spielman et al., Phys. Plasmas 5, 2105 (1998)] at Sandia National Laboratories. Pinhole images will reflect from a planar multilayer mirror onto a microchannel plate detector. A W/Si or Cr/C multilayer reflects a narrow energy range (full width at half maximum <10 eV) centered at 277 eV with peak reflectivity up to 20%. This choice of energy will allow final implosion imaging of any wire-array z-pinch fielded on Z, as well as bench testing using a carbon Kα source. Aluminized parylene filters will eliminate optical and second harmonic reflection, and the 34° multilayer grazing angle will allow detector shielding from high energy x rays produced by the Z accelerator. The system will also include a standard in-line pinhole camera, which can be filtered to obtain simultaneous higher-photon-energy images. Future instruments could use multiple mirrors to image at several energies, or operate at a low grazing angle to image 1–10 keV K-shell emission. [ABSTRACT FROM AUTHOR]

Examines the applications of several novel x-ray imaging schemes to measure plasma parameters in inertial-confinement fusion experiments. Concentration on soft x-ray moire deflectometer approaches and annular coded-aperture microscope; Production of a probe beam with the moire deflectometry approach.

We present diagnostic images taken of an X-pinch plasma x-ray source driven by the XP pulser (100 ns, 500 kA) at Cornell University using an x-ray bubble compound refractive lens. The lens consists of a 200 μm inside diameter glass capillary that contains about 100 biconcave microlenses formed by a string of bubbles in epoxy. A precise system for lens alignment with of 3–5 arcmin accuracy is described. X-ray images of four-wire X pinches were obtained with a spatial resolution of approximately 2 μm. [ABSTRACT FROM AUTHOR]

The performance of image plates based on the photostimulable phosphor BaF(Br,l):Eu2+ has been investigated and compared with x-ray film. Evaluation of detective quantum efficiency (DQE), sensitivity, dynamic range, and linearity was carried out for several types of commercially available image plate, using the Excalibur soft x-ray calibration facility at AWE. Image plate response was found to be linear over a dynamic range of 5 orders of magnitude. One type of image plate was found to have a number of advantages for soft x-ray detection, with a measured sensitivity 1 order of magnitude greater than that of Kodak Industrex CX and DEF-5 x-ray film. The DQE of this plate was found to be superior to that of film at low [less than 103 photons/(50 μm)2] and high fluxes [greater than 104 photons/(50 μm)2]. The spatial resolution of image plates, scanned with several models of commercial image plate readers, has been evaluated using a USAF resolution test target. The highest spatial resolution measured is 35 μm. Though this is significantly lower than the resolution possible with film, it is sufficient for many applications. Image plates were fielded in a refractive x-ray lens imaging diagnostic on the 1 TW Helen laser and these results are discussed. [ABSTRACT FROM AUTHOR]

Reports on the production and characterization of large scale-length plasmas created by illuminating gas-filled thin-walled balloonlike targets using the Nova laser. Targets consisting of a skin surrounding one atom of neopentane; Evaluation of the uniformity of the plasma based on the results.

The TFTR x-ray imaging system (XIS) is an array of 64-Si surface barrier diodes which image the plasma poloidally. Special absorber foils have been installed to permit measurement of electron temperature T[sub e] with < 100-µs time resolution along 10-30 chords. The technique uses the ratio of x-ray fluxes transmitted through two different foils, which depend mainly on T[sub e]. Simulations show that strong line radiation can change this ratio. To correct for these effects, special beryllium-scandium filters are employed to select the line-free region between 2 and 4.5 keV. Separate filter pairs allow correction for strong L line radiation as well as Ti or Ni Kα emission. The T[sub e] determination is based on simulations. Comparison of results with T[sub e] values from the electron-cyclotron emission and x-ray pulse height analysis diagnostics is presented. [ABSTRACT FROM AUTHOR]

An x-ray imaging system is described for 2D reconstructions of plasmas with viewing access limitations. A relatively small number of 72 detectors distributed over six fan arrays first provides partial views of the toroidal plasma in a poloidal plane. Next, the line-integrated data is deconvoluted using a computerized tomographic approach based on linear algebra and a leastsquares fit. The arrangement and the number of detectors have been optimized to the point where significant reconstruction improvements are limited by available viewing access rather than by the number of lines of sight. [ABSTRACT FROM AUTHOR]