Development of a compact high brightness X-ray source

Laser-Compton Scattering (LCS) is one of the most feasible techniques for high quality, high brightness, and compact X-ray source. High energy electron beam produced by accelerators scatters off the laser photon at a small spot. As a laser target, we have been developing a pulsedlaser storage cavity for increasing an X-ray flux. The X-ray flux was still inadequate that was 2.1×105/sec, however, we performed first refraction contrast imaging in order to evaluate the quality of LCS X-ray. Edge enhanced contrast imaging was achieved by changing the distance from sample to detector. The edge enhancement indicates that the LCS X-ray has small source size, i.e. high brightness. We believe that the result has demonstrated good feasibility of linac-based high brightness X-ray sources via laser-electron Compton scatterings.

In the field of application of X-rays, there is a strong need for high brightness, tunable beam. The synchrotron radiation sources meet this demand, but the access time is limited, and they are large and expensive facilities. In this framework, we develop a compact monochromatic high flux X-ray source. The principle lies in obtaining X-ray by Compton backscattering of photons by relativistic electrons. This facility is relatively compact (about 70 m 2 ) to be installed directly in a scientific laboratory, a hospital or an art museum. The backscattered photons are in the range of multi-keV energy, determined by the energy of the electrons and photons. Since there is a correlation between emission angle and energy of scattered photons, the spectral bandwidth of scattered photons can be controlled by simple collimation. The paper presents the ThomX X-ray source consisting of a 50 MeV small storage ring and a laser coupled to a high gain Fabry Perot cavity.

A high brightness, compact plasma x-ray source for x-ray lithography employing a gas-puff z-pinch plasma is developed. This source is designed to direct the x-ray downward into the atmosphere by connecting a diode with a condenser bank through a parallel transmission line and to easily link to a conventional aligner. High x-ray output power is attained by high-repetition-rate discharge (3Hz), developing a fast-acting gas valve. When pinched plasma is formed, the x-rays are emitted from the pinched columnar plasma region (20mm in length and 2mm in diameter). Axial x-ray exposure is achieved by a newly developed x-ray extraction method to reduce the blur in pattern replication caused by the penumbral effect. The x-rays are efficiently extracted through a window highly transparent to x-rays. With this x-ray source, 9-14 A x-rays with 200 J per pulse (600W average power) are obtained using Ne gas plasma in a 3Hz operation. The x-rays through x-ray extraction window (15-μm-thick Be) and x-ray mask (1-μm-thick SiN) have a peak intensity at 12 A wavelengths. The x-ray wavelength is longer than that of a conventional electron impact source. In addition, hard x-rays are not emitted by this plasma x-ray source. High contrast sufficient to replicate fine patterns can be obtained using a mask with a thin absorber, such as 0.4-μm-thick Ta. A 0.2μm resist pattern can be easily replicated.

Simulations of beam optics and bremsstrahlung for high intensity and brightness channeling radiation

Nowadays, the generation of narrow-bandwidth, high brightness, and tunable X-rays via laser-Compton scattering (LCS) is expected for many scientific and industrial applications. In this paper, we will show that the energy recovery linac (ERL)-based LCS X-ray source can be applied to an X-ray imaging of biological specimens.

Spectral brightness and coherent power of radiation from high brightness 1–6 GeV storage rings

We review the development of compact laser-plasma soft x-ray sources based on microscopic liquid drops or liquid jets as target. It is shown that such sources provide practically debris-free, high-flux operation at wavelengths suitable for EUV and x-ray lithography. This regenerative and liquid- density target system holds promise for high-average power x- ray and EUV generation using high-repetition-rate lasers. Application of the method to compact x-ray microscopy is also briefly discussed.

A novel method for generating brilliant x‐ray beams is proposed, in which inelastic collisions of circulating relativistic electrons and a thin wire target are used. The high brilliance of this new photon source is based on narrow angular divergence due to the kinematics of relativistic electrons, and repeated use of electron beams. The estimated brilliance of this source in a 50‐MeV electron storage ring is comparable to that of a compact synchrotron light source.

We demonstrate a high-brightness compact 9 keV electron-impact microfocus x-ray source based on a liquid-gallium-jet anode. A approximately 30 W, 50 kV electron gun is focused onto the approximately 20 ms, 30 mum diameter liquid-gallium-jet anode to produce an approximately 10 microm full width at half maximum x-ray spot. The peak spectral brightness is >2 x 10(10) photons(s mm(2) mrad(2)x0.1% BW). Calculation and experiments show potential for increasing this brightness by approximately three orders of magnitude, making the source suitable for laboratory-scale x-ray crystallography and hard x-ray microscopy.

Aims.We observed the center of the supernova remnant Vela Jr in radio continuum in order to search for a counterpart to the compact central X-ray source CXOU J085201.4-461753, possibly a neutron star candidate which could be the remnant of the supernova explosion.Methods.Observations were made with the Australia Telescope Compact Array at 13 and 20 cm. Spectral indices were obtained using flux density correlations of the data which were spatially filtered to have the same $u-v$ coverage. A multiwavelength search for counterparts to the compact central X-ray source was made.Results.We compiled a new catalogue of 31 small diameter radio sources, including the previously known source PMN J0853-4620, listing the integrated flux densities at 20 cm and, for half of the sources, the flux densities at 13 cm with the corresponding spectral indices. All sources are unresolved at the present angular resolution except for Source 18, which is clearly elongated and lies strikingly close to CXOU J085201.4-461753. Our observations show no evidence for the existence of a pulsar wind driven nebula associated with the point X-ray source. Furthermore, Source 18 has a thermal spectrum with index $\alpha = +0.8 \pm 0.4$ ($S \propto \nu^{\alpha}$), and appears to be the counterpart of the optical source Wray 16-30. In spite of the absence of [O <ns0:sc>iii</ns0:sc>] emission lines as reported in the literature, we find that this object could be explained as a low emission planetary nebula belonging to the “butterfly” morphological class.Conclusions.We conclude that if the radio source 18 is actually a planetary nebula, then CXOU J085201.4-461753 is more likely to be related to it rather than to Vela Jr.

Parametric X-radiation can be described as the diffraction of virtual photons associated with the electric field of a relativistic charged particle passing through a crystal. In analogy with Bragg reflection of X-rays, these diffracted photons appear as real photons, with an energy which satisfies Bragg's law for the reflecting crystal planes. We describe the results of experiments performed on the Naval Postgraduate School linac which were designed to explore the basic properties of PXR in order to assess its potential application as a compact tunable X-ray source. Experiments using a mosaic graphite radiator show that this radiator produced multiple order, narrow bandwidth reflections from 5-45 keV. The measured production efficiency is found to exceed that predicted for spectral orders n>1. We demonstrated the tunability of PXR by rotating the crystal in order to change the Bragg angle relative to the incident 90 MeV electron beam. >

Deep ROSAT HRI (High-Resolution Imager) imaging of the X-ray-emitting gas associated with the colliding elliptical galaxy pair NGC 4782/4783 reveals for the first time the complexity of the hot gas distribution in a pair of close interacting galaxies. The HRI image of NGC 4782/4783 shows hot gas around each galaxy, a high surface brightness X-ray bridge connecting the galaxy pair, tidal-like tails emerging from the two galaxies, and a sheet of gas at the interaction interface between the two galaxies. The hot gas distributions do not peak at the optical centers of the galaxies but are displaced in the same sense as the tidal distensions seen in the optical luminosity distributions. All of these remarkable features show the complexity of structure that develops in the hot gas distribution when both hydrodynamical and tidal forces come into play during collisions between ellipticals with hot gas components. Models by Borne and Colina of the bent two-sided radio jet 3C 278 (associated with NGC 4782) indicated that there must be a strong interaction between the hot gas components of NGC 4782,/4783 and that the deflection of the radio jets is likely caused by the ram pressure exerted on the jet plasma by the hot gas associated with the passing companion NGC 4783. These conclusions are qualitatively confirmed by the HRI image and substantiate the major role played by the hot interstellar medium, and its asymmetries, in the propagation and entrainment of radio jets in colliding radio host ellipticals.

Development of FEL to the VUV/X‐ray region is looked as one of the possible directions to its success. For eliminating the need for optical cavities, difficult to build at that region, we propose a VUV (50 nm) SASE FEL. According to Pellegrini’s scaling law, for a 290 MeV/200 A e‐beam passing through a 10.8 m long and 2 cm period wiggler, a compact VUV coherent radiation source with a high peak power 85.5 MW and a high average brightness 2.44×10+21 (photons/[mm2.mrad2.bw]) can be realized.

A compact soft x-ray reflectometer usable in a small laboratory is developed for measurement of the soft x-ray reflectance of a multilayer mirror in a wide wavelength range, i.e. , including the water window (23 to 44Å). In this reflectometer, the reflectance can be measured as a function of wavelength or incidence angle. A laser-produced plasma soft x-ray source, which is small but has high brightness, makes it possible to construct the compact soft x-ray reflectometer. The soft x rays generated by the source are monochromatized with a grazing incidence reflection grating. Incidence angle dependency of the reflectance can be measured from 2 deg (almost normal incidence) to 85 deg. Reflectances of a Ni/Ti multilayer and a Mo/Si multilayer are measured, and 10.9% at a wavelength of 40.8Å and an angle of 75.1 deg and 38% at a wavelength of 135.5Å and an angle of 25.7 deg from normal incidence are obtained, respectively.

Laboratory water window cryomicroscopy has recently demonstrated similar image quality as synchrotron-based microscopy but still with much longer exposure times, prohibiting the spread to a wider scientific community. Here we demonstrate high-resolution laboratory water window imaging of cryofrozen cells with 10 s range exposure times. The major improvement is the operation of a λ=2.48 nm, 2 kHz liquid nitrogen jet laser plasma source with high spatial and temporal stability at high average brightness >1.5×10(12) ph/(s×sr×μm(2)×line), i.e., close to that of early synchrotrons. Thus, this source enables not only biological x-ray microscopy in the home laboratory but potentially other applications previously only accessible at synchrotron facilities.