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Crystal channeling technology has offered various opportunities in the accelerator community with a viability of ultrahigh gradient (TV/m) acceleration for future HEP collider. The major challenge of channeling acceleration is that ultimate acceleration gradients might require a high power driver in the hard x-ray regime (~ 40 keV). This x-ray energy exceeds those for x-rays as of today, although x-ray lasers can efficiently excite solid plasma and accelerate particles inside a crystal channel. Moreover, only disposable crystal accelerators are possible at such high externally excited fields, which would exceed the ionization thresholds which destroy the atomic structure, so acceleration will take place only in a short time before full dissociation of the lattice. Carbon-based nanostructures have great potential with a wide range of flexibility and superior physical strength, which can be applied to channeling acceleration. This paper presents a beamdriven channeling acceleration concept with CNTs and discusses feasible experiments with the Advanced Superconducting Test Accelerator (ASTA) at Fermilab. [ABSTRACT FROM AUTHOR]

The preliminary experiments of wire array implosion were performed on PTS, a 10 MA z-pinch driver with a 70 ns rise time. A set of diagnostics have been developed and fielded on PTS to study pinch physics and implosion dynamics of wire array. Radiated power measurement for soft x-rays was performed by multichannel filtered x-ray diode array, and flat spectral responses x-ray diode detector. Total x-ray yield was measured by a calibrated, unfiltered nickel bolometer which was also used to obtain pinch power. Multiple time-gated pinhole cameras were used to produce spatialresolved images of x-ray self-emission from plasmas. Two time-integrated pinhole cameras were used respectively with 20-μm Be filter and with multilayer mirrors to record images produced by >1-keV and 277±5 eV self-emission. An optical streak camera was used to produce radial implosion trajectories, and an x-ray streak camera paired with a horizontal slit was used to record a continuous time-history of emission with one-dimensional spatial resolution. A frequency-doubled Nd:YAG laser (532 nm) was used to produce four frame laser shadowgraph images with 6 ns time interval. We will briefly describe each of these diagnostics and present some typical results from them. [ABSTRACT FROM AUTHOR]

Fast Z-pinch has produced the most powerful X-ray radiation source in laboratory and also shows the possibility to drive inertial confinement fusion (ICF). Recent advances in wire-array Z-pinch researches at the Institute of Applied Physics and Computational Mathematics are presented in this paper. A typical wire array Z-pinch process has three phases: wire plasma formation and ablation, implosion and the MRT instability development, stagnation and radiation. A mass injection model with azimuthal modulation coefficient is used to describe the wire initiation, and the dynamics of ablated plasmas of wire-array Z-pinches in (r, θ) geometry is numerically studied. In the implosion phase, a two-dimensional(r, z) three temperature radiation MHD code MARED has been developed to investigate the development of the Magneto-Rayleigh-Taylor(MRT) instability. We also analyze the implosion modes of nested wirearray and find that the inner wire-array is hardly affected before the impaction of the outer wire-array. While the plasma accelerated to high speed in the implosion stage stagnates on the axis, abundant x-ray radiation is produced. The energy spectrum of the radiation and the production mechanism are investigated. The computational x-ray pulse shows a reasonable agreement with the experimental result. We also suggest that using alloyed wire-arrays can increase multikeV K-shell yield by decreasing the opacity of K-shell lines. In addition, we use a detailed circuit model to study the energy coupling between the generator and the Z-pinch implosion. Recently, we are concentrating on the problems of Zpinch driven ICF, such as dynamic hohlraum and capsule implosions. Our numerical investigations on the interaction of wire-array Z-pinches on foam convertors show qualitative agreements with experimental results on the "Qiangguang I" facility. An integrated two-dimensional simulation of dynamic hohlraum driven capsule implosion provides us the physical insights of wire-array plasma acceleration, shock generation and production, hohlraum formation, radiation ablation and fuel compression. [ABSTRACT FROM AUTHOR]

X pinches are well known to produce very small, dense plasma pinches ("hot spots") that emit short bursts of 1.5-8 keV radiation. Hard X-ray radiation in the 8-100 keV range is also emitted, only a small portion of which is associated with the X-pinch hot spot. In hybrid X-pinches, the "long" X-ray pulse is terminated by fast closure of t he gap between the two conical electrodes by rapidly expanding electrode plasmas. The temporal, spectral, and spatial properties of this higher energy radiation, 10-60 keV, have been studied. This radiation was used for point-projection imaging with magnification between 1.5 and 3, and spatial resolution less than 100 micrometers was demonstrated. [ABSTRACT FROM AUTHOR]

Behind-armor debris that results from tungsten rods penetrating armor steel at 2 km/s was studied by analysis of recovered fragments. Fragment recovery was by means of particle board. Individual fragments were analyzed by x-ray tomography, which provides information for fragment identification, mass, shape, and penetration down to masses of a few milligrams. The experiments were complemented by AUTODYN and EPIC calculations. Fragments were steel or tungsten generated from the channel or from the breakout through the target rear surface. Channel fragment motions were well described by Tate theory. Breakout fragments had velocities from the projectile remnant to the channel velocity, apparently depending on where in the projectile a fragment originated. The fragment size distribution was extremely broad and did not correlate well with simple uniform-fragment-size models. [ABSTRACT FROM AUTHOR]

The high-intensive source of soft X-ray emission was developed by femtosecond laser pulses irradiation of submicron size CO2 clusters, produced in custom designed super-sonic nozzle while mixing the 10% CO2+90% He expanding gases. The LiF crystal soft X-ray detectors have been used for obtaining absorption images of ultrathin (nanoscale) foils and biological structures illuminated by the developed source. It was demonstrated that even if the foil is essentially transparent for the soft X-ray radiation (like 100 nm thick Zr foil), the image contrast could be significantly increased due to the influence of propagation-based phase-contrast effect, by placing the detector at the proper distance from the sample. [ABSTRACT FROM AUTHOR]

Magneto-hydrodynamic simulations provide a powerful tool for improving our understanding of the complex physical processes underlying the behavior of wire array Z-pinches. We show how, by using large scale parallel 3D simulations of the array as a whole, it is possible to encompass all of the important features of the wire ablation, implosion and stagnation phases and to observe how these phenomena control the X-ray pulse that is achieved. Comparison of code results with experimental data from the ‘Z’ and MAGPIE pulsed power generators is shown to provide a detailed benchmark test for the models. The simulation results are also used to highlight key areas for future research. [ABSTRACT FROM AUTHOR]

X-ray computed tomography is a powerful non-invasive imaging technique for viewing an object's inner structures in two-dimensional cross-section images without the need to physically section it. The invention of CT techniques revolutionised the field of medical diagnostic imaging because it provided more detailed and useful information than any previous non-invasive imaging techniques. The method is increasingly being used in industry, aerospace, geosciences and archaeology. This paper describes the development of an X-ray computed tomography system for imaging of industrial materials. The theoretical aspects of CT scanner, the system configurations and the adopted algorithm for image reconstruction are discussed. The penetrating rays from a 160 kV industrial X-ray machine were used to investigate structures that manifest in a manufactured component or product. Some results were presented in this paper. [ABSTRACT FROM AUTHOR]

Material flow in FSW is being studied here. It is shown how X-Ray computed microtomography (μCT) can be applied for the visualization of Ti-powder which is implanted into Al-sheets as marker material. During welding of the sheets the process is rapidly stopped and the region around the weld pin is being studied by μCT. Volume data sets of the marker distribution have been generated and are presented. Material flow is compared for material originating from two different positions and for two different tool geometries. Significant differences in the flow patterns have been seen. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The Nanometer Optical Component measuring Machine (NOM) has been developed at BESSY for the purpose of measuring the surface figure of optical components up to 1.2 m in length used at grazing incidence in Synchrotron Radiation beamlines. It is possible to acquire information about slope and height deviations and the radius of curvature of a sample in the form of line-scans and in a three dimensional display format. With the NOM surfaces up to 600 cm2 have been measured with an estimated measuring uncertainty in the range of 0.01 arcsec rms and with a correspondingly high reproducibility. This is a five to tenfold improvement compared to the present state of the art of surface measuring techniques. The engineering conception, the design of the NOM and the first measurements are discussed in detail. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

CMOS imagers are matrix-addressed photodiode arrays, which have been utilized in devices such as commercially available digital cameras. The pixel size of CMOS imagers is usually larger than that of CCD and smaller than that of TFT, giving them a unique position. Although CMOS x-ray imaging devices have already become commercially available, they have not been used as an x-ray area detector in synchrotron radiation experiments. We tested performance of a CMOS detector from Rad-icon (Shad-o-Box1024) in medical imaging, small-angle scattering, and protein crystallography experiments. It has pixels of 0.048 mm square, read-out time of 0.45 sec, 12-bit ADC, and requires a frame grabber for image acquisition. The detection area is 5-cm square. It uses a Kodak Min-R scintillator screen as a phosphor. The sensitivity to x-rays with an energy less than 15 keV was low because of the thick window materials. Since the readout noise is high, the dynamic range is limited to 2000. The biggest advantages of this detector are cost-effectiveness (about 10,000 US dollars) and compactness (thickness < 3 cm, weight < 2 kg). © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The last 25 years have seen an explosion in the number of new x-ray based imaging methods and applications. In reviewing these new capabilities we see that the ability to generate improved data quality underlies a number of the major advances. Improvement in the quality of x-ray sources, in detector resolution and dynamic range, in data analysis methods both in image processing and in reconstruction techniques have yielded significant advances in image quality. In addition to the improved imaging hardware, the use of computers play a key role in extending capabilities in high speed computed tomography, in real time image enhancement, in automated defect recognition and in the development of accurate x-ray inspection simulations. The ability to generate information and to analyze the complexities introduced by typical inspection demands can quickly outstrip even today’s computational resources. Developments in parallel computing and computer memory are beginning to managing the huge data volumes now routinely produced and open up a number of new applications. Some examples include high-resolution 3D-image generation with the capability to probe micron length scales, dual energy computed tomography providing improved airport security, materials characterization techniques providing new tool for process development, and x-ray image formation modeling. The ability to model the details of the generation of bremsstrahlung radiation and its interaction with the complex geometry of the object under consideration provide for the first time a means to determine and quantify the optimal parameters for an inspection. These advances over the last 25 years represent exciting time in x-ray imaging, the impact of which will be played out in the next decade. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

This paper deals with the X-ray inspection of objects translating upon a conveyor belt. When volumetric information about the object is required, a solution consists in using a limited number of X-ray viewpoints, typically 3 to 6. The projections can be combined using an iterative Algebraic Reconstruction Technique (ART). Nevertheless, the ART algorithm adapted to our specific geometry still provides underestimated quantitative values. In this paper, we propose to reconstruct accurate 3D quantitative measures inside the object, by integrating a priori knowledge concerning the object when available. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In a previous laboratory study, it has been shown that x-rays can be used for corn flow rate measurements. In addition to the corn, there are many other agricultural crops and chemicals that require accurate flow rate measurements. Development of x-ray based techniques for flow rate quantification of such materials should be preceded by data about how those chemicals and products attenuate x-rays and what kind of x-ray tube operating parameters need to be used for measurements. In this work, feasibility of using x-rays for measuring flow rates of such materials have been studied both theoretically and experimentally. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]