High-power X-ray Source Research Articles

X-ray framing camera for pulsed, high current, electron beam x-ray sources

High power x-ray sources built for nuclear weapons effects testing are evolving toward larger overall diameters and smaller anode cathode gaps. We describe a framing camera developed to measure the time-evolution of these 20-50 ns pulsed x-ray sources produced by currents in the 1.5-2.5 MA range and endpoint voltages between 0.2 and 1.5 MV. The camera has up to 4 frames with 5 ns gate widths; the frames are separated by 5 ns. The image data are recorded electronically with a gated intensified CCD camera and the data are available immediately following a shot. A fast plastic scintillator (2.1 ns decay time) converts the x-rays to visible light and, for high sensitivity, a fiber optic imaging bundle carries the light to the CCD input. Examples of image data are shown.

Compact single and nested tungsten-wire-array dynamics at 14–19MA and applications to inertial confinement fusion

Wire-array z pinches show promise as a high-power, efficient, reproducible, and low-cost x-ray source for high-yield indirect-drive inertial confinement fusion. Recently, rapid progress has been made in our understanding of the implosion dynamics of compact (20-mm-diam), high-current (11–19MA), single and nested wire arrays. As at lower currents (1–3MA), a single wire array (and both the outer and inner array of a nested system), show a variety of effects that arise from the initially discrete nature of the wires: a long wire ablation phase for 50%-80% of the current pulse width, an axial modulation of the ablation rate prior to array motion, a larger ablation rate for larger diameter wires, trailing mass, and trailing current. Compact nested wire arrays operate in current-transfer or transparent mode because the inner wires remain discrete during the outer array implosion, even for interwire gaps in the outer and inner arrays as small as 0.21mm. These array physics insights have led to nested arrays that produce radiation pulse shapes required for three-shock low-adiabat compression of high-yield inertial confinement fusion capsules.

Recombination X-ray Radiation from Plasma Liners

The possibility of creating a high-power X-ray source based on the recombination radiation mechanism has been studied and analyzed. The recombination X-ray radiation from neon, aluminum, and argon was obtained in experiments with plasma liners performed on the GIT-12 setup using a current pulse amplitude of ∼2.5 MA and a leading pulse front width of ∼300 ns. The obtained results show that the recombination mechanism of X-ray generation offers good prospects for the development of a high-power X-ray source with photon energies in the 7–20-keV range.

On the possibility of high-temperature plasma production by laser pulses irradiating a volume-structured medium formed upon the explosion of a thin conductor

The properties and parameters of volume-structured metal media produced by exploding thin conductors in a high-power electric discharge are analysed. Such media are proposed for the production of nonequilibrium high-temperature laser plasma as a high-power X-ray and neutron radiation source. The physics of the interaction of a high-power laser pulse with a volume-structured metal medium and the properties of produced nonequilibrium plasma are considered.

Development of a Novel Instrument for X-Ray Photoelectron Diffraction and Holography

For X-ray photoelectron diffraction (XPED) and holography measurements we developed a novel laboratory instrument with the multienergy high power X-ray source and the high energy and high angular resolution photoelectron spectrometer system. The photon intensities of Al–Kα, Cr–Lα and Cu–Kα were estimated at 4.6 × 1011 cps, 7.5 × 1010 cps and 7.2 × 1010 cps, respectively. Ag3d XPS also revealed that the energy resolutions of Al–Kα and Cr–Lα sources were 0.9 eV and 3.1 eV, respectively. XPS and XPED of h-BN/Ni(111) excited by Al–Kα and Cr–Lα elucidated the potential and the validity of the XPED and holography analysis by using this novel instrument. Cu–Kα excitation XPS and Ti1s XPED measurements of the SrTiO3 (001) surface have also been performed.

回折面アパーチャを用いたＸ線光電子回折パターンの高角度分解能測定

We have been carrying out a X-ray Photoelectron Diffraction (XPED) measurements by using a new input-lens-system and a high power X-ray source. In the new input-lens-system, high angle resolution and high throughput are accomplished by placing an aperture not on the image plane but on the diffraction plane of electron optics. The focal position on the diffraction plane has a linear relationship to the emission angle and is independent of kinetic energy. The angular resolution is numerically obtained as a function of the aperture size. A high angular resolution is therefore easily achieved with a small aperture. In the angle-resolving lens system, aperture sizes (φ4 mm, φ2 mm, φ0.5 mm, φ0.25 mm) correspond to the angular resolutions (± 0.6°, ± 0.3°, ± 0.08°, ± 0.04°) respectively. High angle-resolved XPED patterns from Ge (111) are obtained. Detected photoelectron intensities are high enough to measure the PED pattern even if angle resolution is 0.04°. Moreover, fine structure of the PED pattern such as the Kikuchi pattern can be measured clearly.

Study of phase formation of implantation layers by Al–MePBII into AgMgNi alloy

Al-PBII into AgMgNi alloy is carried out using the unbalance magnetron sputtering (UBMS) target and r.f. stimulation to generate metal plasma with a dynamic MePBII model. The depth profiles are acquired by XPS analysis. The details of the phase constitute that the samples are detected by both XRD analysis with a high power X-ray source (HPXRD) and a glancing XRD (GXRD) method. TEM image is used to further affirm the existence of a new alloy phase and describe the cross-section distribution of the new alloy phase. The results show that an Al implantation layer appears on the surface of AgMgNi alloy substrates. The contents of Al in the implantation layer decreased with increasing depth. The μ-Ag 3Al phase is detected by HPXRD analysis. Further identification is done by TEM. The μ-Ag 3Al phase is mainly formed in the region between the columnar Al layer on the surface and the Ag substrate. The orientation of μ-Ag 3Al phase is related to the orientation of Ag substrate, which was produced by the fabrication of the original sample.

Monte Carlo simulation of x-ray generation and energy dissipation in a W/Cu target for optimum design of a high-power x-ray source

Monte Carlo simulation of x-ray generation by electron impact was applied to a W/Cu target (tungsten W film on a copper substrate) to find the optimum conditions for a high-power x-ray source. To assess the performance of the high-power x-ray source, we propose using: The total intensity of continuous x-rays emitted from the target, , where i(λ) is a spectrum of continuous x-rays emitted from the target under bombardment of an electron beam of primary energy E0. The cooling efficiency of the W/Cu target, which is where and σj are the in-depth energy dissipation in a target of element j and the thermal conductivity of element j, respectively, in the W/Cu target with tungsten film thickness ΔW. Both I and γ were obtained from Monte Carlo calculations for different tungsten film thicknesses by varying the incidence angle of the electron beam and the take-off angle of the x-rays according to the primary energy levels of the electron beam. Copyright © 2002 John Wiley & Sons, Ltd.

A Photoelectron Spectro-Holography Apparatus.

We have constructed a photoelectron spectro-holography apparatus, which consists of a high-power X-ray source generation system with rotating anodes and a high-performance angle-resolving electron energy analyzer. These systems have been specially designed for X-ray photoelectron diffraction and photoelectron holography. In this paper, we describe this apparatus from technical points of view.

Continuum X-Ray Generation from W Film on Cu Substrate

The dependence of the continuum X-ray generation from a W film on the primary energy (15 to 30 keV) and film thickness (0.1 to 0.7 µm) have been investigated by experiment and Monte Carlo (MC) simulation in order to develop a high-power rotor-type X-ray source of high efficiency. The continuum X-ray spectra obtained by MC simulation show excellent agreement with the experimental data, confirming the fact that the present MC simulation is applicable for a systematic study to optimize the construction of an X-ray source. The dependence of the continuum X-ray generation on the thickness of the W film has revealed that the continuum X-ray spectra from the W film of thickness ∼0.7 µm are almost similar to those of the bulk W in the investigated range of primary energies. This indicates that the thickness of the W film of ∼0.5 µm is sufficient for the rotor-type X-ray source, although a commercial-type source is of the order of hundreds µm with the primary energy of ∼50 keV.

A new ESCA instrument with improved surface sensitivity, fast imaging properties and excellent energy resolution

Results from the first experiments with a new ESCA instrument with monochromatic X-ray excitation are presented. The measurements were selected to assess the performance of the instrument in terms of energy and spatial resolution, information rate and surface sensitivity, and to probe the new dimension added to XPS analysis with the introduction of an imaging system. Novel design features described in the paper include a high-power monochromatic X-ray source and an electrostatic lens system permitting either large luminosity or high spatial resolution. A new geometry allows excellent access to the sample area and gives maximum surface sensitivity at glancing angles. The best energy resolution achieved so far with the instrument has been evaluated from the Fermi edge of silver to 0.27 eV (FWHM). The FWHM of the Ag 3d 5 2 line at this resolution is 0.44 eV. At an instrument energy resolution of 0.37 eV (FWHM) a peak intensity of the Ag 3d 5 2 line corresponding to a single-channel detector count rate of 1.9*10 6 cps has been measured. At this resolution, high quality spectra from surface elements of 30 μ × 30 μm can be recorded in a few minutes. The spatial resolution (20%–80%) has been measured to 23 μm. The enhanced surface signal at glancing angles is demonstrated in a series of measurements of the angular dependence of the XPS spectrum from a silicon surface. Preliminary experiments using an image integrating system show the potential of the combination of high spatial resolution in XPS with such techniques to give new information on the distribution of chemical properties or electrostatic potential variations over a surface. Future developments are discussed, including parallel recording of spectra from a large number of small spots, advanced handling of information from an imaging XPS system and further improvements of the spatial resolution.

Recent developments in X-ray lithography systems

High resolution, high throughput x-ray lithography systems are being developed to meet future needs for submicron integrated circuit fabrication. An advanced step-and-repeat x-ray system, under development at the Perkin-Elmer Corporation, is described. The critical technologies, precision alignment and high-power x-ray source, are explored. To achieve half-micron or better resolution, overlay accuracy of at least 0.1 micron is required. This is achieved by a proximity system that controls alignment in six degrees of freedom on a field-by-field, real-time basis. Alignment techniques are described and overlay measurements presented for Boron Nitride mask-to-wafer levels. The demands placed on the x-ray source are great. High power is required to achieve practical levels of throughput, and a finite x-ray emitting area is required to achieve a small penumbra blur. The source developed achieves a system resolution of 0.2 micron or less, with a throughput of 40 wafer levels per hour. Experimental results on this source are shown.

Determination of Diffusion Coefficients of Self-Interstitials in Ice with a New Method of Observing Climb of Dislocations by X-Ray Topography

The diffusion coefficients of self-interstitials in ice were determined from the growth processes of interstitial-type dislocation loops and dipoles introduced by cooling on the basis of the fact that the growth takes place by the diffusion of excess interstitials to dislocations. The time variation of their size was obtained by in situ X-ray topographic observations using a high-power X-ray source. By combining the obtained diffusion coefficients and the equilibrium concentration of interstitials previously obtained, it is possible to determine the self-diffusion coefficient Ds in ice. The value of Ds obtained by this method and its activation energy E coincide well with those determined by tracer experiments. This result confirms the interstitial mechanism for self-diffusion in ice.

Study of vacancy clustering in e-irradiated copper by small-angle X-ray scattering

The small-angle scattering (SAS) from single vacancies and vacancy clusters in Cu has been observed using a position-sensitive detector system in combination with a high-power (100 kW) rotating-anode X-ray source. The single vacancies were produced at 4 K by irradiation with 3 MeV electrons, and the annealing of the SAS patterns (measured at 4 K) was studied. The experimental results were compared with calculated patterns based on atomistic models for vacancies and vacancy clusters with appropriate corrections for lattice displacements as well as interstitial scattering, For annealing temperatures below 200 K, the SAS patterns corresponded to the expected scattering for single vacancies. Above 200 K, changes in the patterns consistent with the nucleation of small vacancy clusters were observed. These clusters had room-temperature radii of about 7 Å.

X-ray exposure system using finely position adjusting apparatus

An apparatus for finely adjusting the three-dimensional position of a workpiece and the application of this apparatus to high power x-ray lithography are presented. The relative positioning apparatus has been designed, using electrodynamic transducers for the x, y, and z directions and an electrostrictive transducer for rotary direction (ϑ). Motions in each direction are supported by a resilient plate. The relative position of mask and wafer has been detected by applying a mechanical vibration to the wafer, with an accuracy of less than ±0.1 μm. The fine positioning mechanisms have displayed excellent performance with high accuracies. As a first step to constructing a working apparatus, a prototype exposure system was built using pattern replication in an atmospheric environment, comprised of a positioning system and a high-power x-ray source with a rotary Al target operated at more than 20-kW electron-beam input power. The characteristic x ray has been irradiated on a wafer through a contractile vacuum pipe. Using an exposure test, the system functions have been confirmed as a fine pattern replicating system.

High-power ultraviolet and x-ray sources

The review is devoted to the problem of using cyclic electron accelerators and storage rings as sources of high-power ultraviolet radiation and x rays. A brief description is given of the properties of synchrotron radiation and also of the undulatory radiation which can be generated in such installations. Particular cases of use of these radiations are discussed. The parameters of Soviet accelerators and storage rings and the intensities of the synchrotron radiation beams from these installations in the far ultraviolet and x-ray regions of the spectrum are given. These characteristics are compared with the corresponding data for the DESY synchrotron at Hamburg, whose radiation is extensively used for x-ray structural analysis of biological polymers, investigation of the electronic structure of solids and gases, surface phenomena, and many other purposes.

Мощные источники ультрафиолетового и рентгеновского излучения

Мощные источники ультрафиолетового и рентгеновского излучения

A refinement of the values of the lattice parameters in the crystal structure of amphibian fresh yolk platelets by X-ray crystallography

A refinement of the values of the lattice parameters of the crystal structure of fresh yolk platelets of an amphibian, Rhacopholus schlegelii var. arborea , was done by means of X-ray diffraction using a high power X-ray source. The densitometric tracing of small-angle X-ray diffraction photographs by a microphotometer reveals nineteen reflections, which show a series of typical interplanar spacings. Crystallographic analyses based on the graphical method with the Hull-Davey chart indicate that the crystalline lattice of the fresh yolk platelets is a hexagonal system and the values of the lattice parameters are: a = 110.5 ± 1 Å, c = 239.8 ± 2 Å, and axial ratio, c/a = 2.17.