Measurements of soft x-ray emission from a nitrogen/helium double-stream gas puff target irradiated with the Prague Asterix Laser System (PALS) have been performed. The aim of the studies was to measure the absolute yields of soft x-ray radiation in the water window from a gas puff laser plasma source and to verify the possibilities of using of this source in x-ray imaging microscopy.

The vacuum spark X-ray source is a device operating at high frequency, of the order of several kilohertz, where the X- rays are emitted in small dose in each pulse. At ALFT, we are developing such X-ray sources for lithography in a series of models called VSX. Continuous operation at 10 kHz, full voltage (14~15 kV) for more than 9 hours has been routinely obtained with a carefully designed trigger and a movable anode. The X-ray output is 275 (mu) J/pulse at the source with a capacitance of 13 nF. An extendibility study has been carried out focused mainly on debris management and heat dissipation. The study evaluated the possibility of extending the machine to the 150 W X-ray output level required by the semiconductor industry within the operating regime of 40 kHz and anode moving at speed up to 11.2 m/sec.

A novel soft X-ray source has been developed that generates soft X-rays of 2.36 nm wavelength. The source is based on focusing a 10 keV electron beam on a continuous jet of water, exciting oxygen K_(alpha ) characteristic radiation. A high-resolution spectrum was recorded which shows a background-free peak at 2.36 nm with a FWHM of 0.017 nm. The brightness of this source is limited by the amount of electron energy that can be dissipated inside the water jet, without endangering the stability of the source. We succeeded in focusing 60 (mu) A onto one side of the jet, at which value the brightness is ~5*10⁸ photons/(sec sr micrometers ²). The source is of potential interest for use in tabletop soft X-ray microscopy, because the line radiation falls just within the water window, the wavelength region that is employed in this type of microscopy.

We report on the recent progress of a compact laser Compton monochromatic X-ray source based on the inverse Compton scattering of 100mJ, 100 femtosecond laser pulses by 13MeV, 3 picosecond, InC electron bunches. Experimental results are reviewed on the 4.6keV, 3 picosecond and 2.3keV, 300 femtosecond X-ray pulses.

A compact indirect laser-driven ultrashort electron and hard-x-ray source based on the combination of a high-repetition rate femtosecond laser system with a conventional x-ray tube is demonstrated. The influence of laser parameters on thermionic electron emission and on the hard-x-ray generation efficiency is studied. This source has an outstanding performance in terms of average power, simplicity, handling, and applicability as compared to the sources based on high-power laser-produced plasmas.

The x-ray emission of Ti, Fe, Mo, W and Pt x-pinches are currently bieng studied at the Nevada Terawatt Facility z- pinch machine (0.9-1.0 MA, 100 ns). New x-ray diagnostics for time-resolved spectroscopy and imaging has been developed and used in x-pinch experiments. The total x- ray/EUV yield was more than 10 kJ. The minimum x-ray pulse duration was 1.1 ns (Mo, W, Pt). For Ti, Mo and W pinches x-ray pulses occurred in two or three groups in the narrow time intervals after the start of the current. The most compact emitting region has been observed for a planar-loop Mo x-pinch (the number of hot spots ranging from 1-5 with a minimum size smaller than 30 micrometers at (lambda) <1.5-2 Angstoms). Strong jets were observed (Ti, Fe, Mo) directed toward the discharge axis, perpendicular to the wires. A structure of an x-pinch includes energetic electron beams directed toward the anode and along wires. The total beam energy increases from Ti to W. A pulse of hard x-ray radiation was observed moving upwards along the axial axis with an energy of several hundred keV(Mo). The size of this source was smaller than 1 mm. The measurements of temperature and density of x-pinch plasmas were based on theoretical modeling of K-shell Ti and L-shell Mo spectra (T_e=1.5 keV for Ti, 0.8 keV for Mo, N_e up to 2- 3x10²² cm^-3 with 1-10% of hot electrons).

More than 100 years after the discovery of X-rays by Roentgen the basic design of X-ray tubes remains nearly unchanged. A polychromatic spectrum of X-rays is generated by deceleration of electrons in a heavy (metal) target, superimposed by the characteristic fluorescence lines of that material. Nowadays, in many applications the need for near monochromatic radiation is beneficial or even mandatory. In this paper an X-ray tube is described which emits a spectrum consisting only of characteristic fluorescence radiation. Measurements of the yield and spectral distribution are presented, as well as possible applications.

The challenges that medical diagnostic x-ray source engineers must meet depend upon the modality. Cardiac-x-ray sources must improve both fluoro and cine high power output while maintaining small physical size and weight. Angiography must have small focal spots for higher magnification work as well as high power capability using the large focal spot. Some filtration is applied to modify the bremsstrahlung spectrum so that maximum contrast can be achieved with contrast-enhancing agents in the patient's body. Computed tomography (CT) sources have design requirements that take into account the source's increasingly rapid circular motion about the patient's body and tight specifications on focal spot motion and drift. The decrease in scan time requires an increase in source power in order to maintain sufficient x-ray photon flux density at the detector elements for proper signal-to-noise. Mammography x-ray sources face a demand for higher power in smaller focal spots at low electron accelerating voltage. Although focal spot sizes approach 0.1 mm, the resolution of small tissue abnormalities remains a current problem. Management of the dose to the patient is a concern that is common to all the modalities.

Polycapillary x-ray optics provide an innovative new way to control x-ray beams. Placing these optics after the object to be imaged provides very efficient rejection of Compton scatter, while allowing image magnification without loss of resolution, image demagnification, or image shaping to match with digital detectors. An extensive study of the effects of surface and profile defects have greatly enhanced the understanding of the manufacturing process and lead to improved reproducibility and manufacturability of the optics. Measurements were performed on magnifying tapers. The optics had measured primary transmissions greater than 50% and scatter transmission of less than 1%. For a 5-cm thick Lucite phantom, this resulted in a contrast enhancement compared to a conventional grid of nearly a factor of two. The magnification from the tapered capillary optics improved the MTF at all frequencies out to 1.9 times the original system resolution. Increases below the system resolution are most important because clinically relevant structures generally occupy lower spatial frequencies. Alternatively, placing a collimating optic and diffracting crystal before the patient provides sufficient monochromatic beam intensity for medical imaging. Contrast, resolution, and intensity measurements were performed with both high and low angular acceptance crystals. At 8 keV, contrast enhancement was a factor of 5 relative to the polychromatic case, in good agreement with theoretical values. At 17.5 keV, monochromatic subject contrast was more than a factor of 2 times greater than the conventional polychromatic contrast. An additional factor of two increase in contrast is expected from the removal of scatter obtained from using the air gap which is allowable from the parallel beam. The measured angular resolution after the crystal was 0.4 mrad for a silicon crystal. The realization of these applications has been advanced by the recent marked improvement in available optic quality and reproducibility. Manufacturing progress has been assisted by the development of simulation analyses which allow for increasingly accurate assessment of optics defects. Optics performance over the whole range of energy from 10 to 80 keV can often be matched with one or two fitting parameters. Continuing optics manufacturing challenges include the advance of applications at energies above 40 keV and the production of optics for imaging which are of adequate clinical size. Multioptic jigs designed to increase imaging area have been tested.

Focusing mirrors with various curvatures have been constructed by clamping flat foils in formers machined to the appropriate shape by numerically controlled spark erosion. Manufacturing errors are discussed and the measured imaging accuracy and efficiency are described.

Polycapillary and doubly curved crystal x-ray optics have gained broad acceptance and are now being used in a wide variety of applications. Beginning as optics integrated into research setups, they were then used to enhance the performance of existing x-ray analytical instruments and are now widely used as essential components in x-ray spectrometers and diffractometers designed to utilize their capabilities. Development of compact x-ray sources, matched to the optic input requirements have allowed large reduction in the size, power, and weight of x-ray systems which are now resulting in development of compact x-ray instruments for portable, remote, or in-line analytical tools for new applications in industry, science, or medicine.

A simple model of X-Ray standing waves (XSW) formation in the slit between two polished parallel flat plates formed a planar X-Ray waveguide for the angle area restricted by the critical total reflection angle is developed. It is shown that the model is true for a case of the Bragg reflection. The conditions required for XSW to appear in the slit space are formulated and a slit size interval conforming to these conditions is evaluated. A mechanism of a XSW intensity decrease in a planar X-ray waveguide is proposed. The efficiency of the waveguide on a comparison base of the X- Ray forming system completed by a slit-cut superposition set with one equipped by a planar X-Ray waveguide is evaluated. Some recommendations on the application of the planar X-Ray waveguide in X-Ray structural and spectral studies of surface are presented.

Lithium is the best material for refractive x-ray lenses, with peak performance around 8 keV. To date we have built a prototype of Cederstrom's so-called alligator lens, and have tested the lens with beamline 7ID's 10 keV x-rays on the Advanced Photon Source at Argonne National Laboratories. To date we have attained only a threefold gain, most likely limited by surface roughness that is avoidable with more careful manufacturing techniques.

In this paper, we describe a low power system using Polycapillary collimating and focusing optics that were designed to collect Cu Ka radiation from an Oxford Ultra-Bright micro-focus source for X-ray powder diffraction measurements. The characterizations of the source and polycapillary optics are presented. A collimator with two apertures was used to block high energy X-rays. An optic alignment system was designed to optimize coupling between the optics and the source, taking into account the maximum radiation direction from the source. Several powder sample data sets were collected with this system and their qualities are compared with data sets from the same samples taken with an Enraf-Nonius FR590 sealed-tube source system. Discussion is also presented for further improving the performance of this low power system.

This paper describes the development of a prototype in-line process monitor for galvannealing processes in the steel industry using parallel beam X-ray diffraction. The implementation of this is to design a simplified X-ray diffraction system monitoring a single phase (FeZn (xi) phase)of the steel surface coating during the galvannealing process. A laboratory base system was built with a low power source combined with a polycapillary collimating optic. Data sets from several steel samples were collected and analyzed. Two-dimensional polycapillary angular filters were used in this system and show that they could increase the single-noise ratio. Data acquisition times were also estimate to detect a change in phase composition. The direction of future work and system improvements for in-line application is also discussed.

We have been developing a debris-free laser plasma light source with a gas-puff target system whose nozzle is driven by a piezoelectric crystal membrane. The gas-puff target system can utilize gases such as CO₂, O₂ or some gas mixture according to different experiments. Therefore, in comparison with soft X-ray source using a metal target, after continuously several-hour laser interaction with gas from the gas-puff target system, no evidences show that the light source can produce debris. The debris-free soft X-ray source is prepared for soft X-ray projection lithography research at State Key Laboratory of Applied Optics. Strong emission from CO₂, O₂ and Kr plasma is observed.

In the study (SPIE 4144, 128 (2000)) we have presented results of the experimental study of a strongly nonuniform spatial distribution of output keV and sub-keV radiation, that transported by different types of glass mono- and policapillary converters from the point x-ray laser plasma and z-pinch plasma sources. In this paper the features of x-ray radiation are analyzed theoretically using the Fresnel-Kirchhoff diffraction theory and the method of images. We show that the wave effects can strongly affect properties of the x-ray capillary optics.

Wave effects in mono- and poly-capillary x-ray optics are studied theoretically. We consider the guided propagation of continuous-wave x-ray radiation in the spectral region of 0.01-1 nm. Optical guiding of x-ray ultra-short pulses is also studied. We show that the wave effects can strongly affect properties of x-ray capillary optics. The necessary conditions for the strong influence of the diffraction and interference on the guided propagation of x-rays are presented.

A compact laser produced plasma x-ray source radiates 24 Watts average power of 1nm x-rays in 2(pi) steradians. The x-ray power conversion efficiency is 9% from the laser average power focused on the x-ray target. The laser-plasma x-ray source is generated by a 300W compact, diode-pumped, solid-state Nd:YAG laser system. The tabletop laser system is constructed on a 4ft x 8ft optical bench and the laser modules are 1ft high. The total wall-plug power consumption for this laser-produced-plasma x-ray source is 22 kW. The x-ray source is optimized for integration with and x-ray stepper to provide a complete x-ray lithography exposure tool for the manufacture of high speed GaAs devices.

We discuss technology that will produce a wide angle monochromatic beam of X-rays that appears to diverge from a virtual point source. Although our ideas are discussed in the context of dual energy subtraction angiography (DESA) that we are developing to operate in a clinical setting, they are widely adaptable to all applications of x-ray radiography. The best DESA analysis is obtained from X-ray images made in narrow energy bands just below and just above the I K-absorption edge. Our monochromator will be used to isolate these narrow bands to produce high contrast, high spatial resolution, ECG gated angiographic images. Emission lines, that have X-ray energies below (E-) and above (E+) the I K-absorption edge at 33.2 keV, are readily available. We have deposited variable d-spacing artificial crystals, called multilayers, on optically flat, very smooth substrates, to create narrow pass band X-ray monochromators centered on La and Ba K-emission lines. We will record (E-) and (E+) exposures on either photographic plates or, in the future, with energy sensitive pixelated arrays of solid state detectors. After a suitable normalization, the exposures will be subtracted to yield a high resolution, high contrast image of the I filled arteries. Although initial results will be obtained with conventional X-ray tubes, our goal is to couple the monochromators to a high intensity, laser produced, X-ray plasma. We will present early test data that shows the multilayer performance.