Total X-ray Flux Research Articles

The X-ray rise and fall of the symbiotic recurrent nova system T CrB

ABSTRACT We present the analysis of publicly available NuSTAR, Suzaku, and XMM–Newton observations of the symbiotic recurrent nova T CrB covering the 2006.77–2022.66 yr period. The X-ray spectra are analysed by adopting a model that includes a reflection component produced by the presence of a disc that mimics the accretion disc and the immediate surrounding medium. Our best-fitting model requires this disc to have a radius of 1 au, effective thickness of 0.1 au, averaged column density 10$^{25}$ cm$^{-2}$ and orientation of 50$^{\circ }$ with respect to the line of sight. This disc is about a factor of two larger than recent estimations for the accretion disc and its presence contributes significantly via reflection to the total X-ray flux detected from T CrB, which naturally produces the emission of the 6.4 keV Fe line. Our analysis suggests that the temperature of the boundary layer evolved from 14.8 keV in the steady-state phase (before 2016), to 2.8 keV in the 2017.24 epoch, to finally stabilize to about $\sim$8 keV in the subsequent epochs. These variations in the plasma temperature of the boundary layer are attributed to the evolution of the mass accretion rate ($\dot{M}_\mathrm{acc}$), which is estimated to have an averaged value of $\dot{M}_\mathrm{acc}$ = 2.6$\times \,10^{-8}$ M$_\odot$ yr$^{-1}$ for the current active phase. The presence of emission lines in the XMM–Newton Reflection Grating Spectrometer spectrum of 2017.24 prevents from adopting a blackbody emission model to fit the soft X-ray range. Instead, we use plasma emission models that suggest the presence of adiabatically shocked gas produced by gas velocities of 110–200 km s$^{-1}$, very likely tracing jet-like ejections similar to what is found in other symbiotic systems. The analysis of X-ray and optical data together show that T CrB has a similar evolution as black hole binaries, accreting neutron stars and active galactic nuclei in the hardness–intensity diagram.

Analysis of the off-focal source in transmission geometry X-ray systems

For X-ray tubes in lab based computed micro-tomography systems, off-focal X rays are those emitted from the source but not produced at the primary focal spot of the electron beam. They can be attributed to both electron and photon scatter within the X-ray tube. Off-focal X rays can represent a significant fraction of the total X-ray flux and lead to artefacts in the radiographs, and reconstructed tomographic volumes, degrading contrast and resolution. Therefore, they are an undesirable feature in industrial and medical X-ray CT scanners. In this work, a general model of an X-ray tube with a transmission target has been developed in TOPAS, a Monte Carlo (MC) simulation extension to GEANT4. MC simulations enable: (1) the analysis of the origin of various types of off-focal X rays; (2) quantification of the prevalence of each type for a specific tube geometry and (3) replication and understanding of experimental results affected by off-focal X rays. Our MC analysis herein shows that the amount of off-focal X rays can represent up to 25% of total X-ray flux. The most prevalent off-focal X rays were found to be the X rays created by the electrons back-scattered from the target into the aperture and generating X rays.

NuSTAR Hard X-Ray Monitoring of Gravitationally Lensed Quasar RX J1131–1231

The X-ray emission from active galactic nuclei is believed to come from a combination of inverse Compton scattering of photons from the accretion disk and reprocessing of the direct X-ray emission by reflection. We present hard (10–80 keV) and soft (0.5–8 keV) X-ray monitoring of a gravitationally lensed quasar RX J1131−1231 (hereafter RXJ1131) with NuSTAR, Swift, and XMM-Newton between 2016 June 10 and 2020 November 30. Comparing the amplitude of quasar microlensing variability at the hard and soft bands allows a size comparison, where larger sources lead to smaller microlensing variability. During the period between 2018 June 6 and 2020 November 30, where both the hard and soft light curves are available, the hard and soft bands varied by factors of 3.7 and 5.5, respectively, with rms variability of 0.40 ± 0.05 and 0.57 ± 0.02. Both the variability amplitude and rms are moderately smaller for the hard X-ray emission, indicating that the hard X-ray emission is moderately larger than the soft X-ray emission region. We found the reflection fraction from seven joint hard and soft X-ray monitoring epochs is effectively consistent with a constant with low significance variability. After decomposing the total X-ray flux into direct and reprocessed components, we find a smaller variability amplitude for the reprocessed flux compared to the direct emission. The power-law cutoff energy is constrained at keV, which positions the system in the allowable parameter space due to the pair production limit.

XMM-Newton observation of the TeV-discovered supernova remnant HESS J1534-571

We report the results obtained from XMM-Newton observations of the TeV-detected supernova remnant (SNR) HESS J1534-571. We focus on the nature of the cosmic-ray particle content in the SNR, which is revealed by its γ-ray emission. No signatures of X-ray synchrotron emission were detected from the SNR. This is consistent with earlier results obtained with Suzaku from other regions of the object. A joint modeling of the XMM-Newton and Suzaku spectra yields an upper limit for the total X-ray flux from the SNR area of ~5.62 × 10−13 erg cm−2 s−1 (95% C.I.) in the energy band of 2.0–10.0 keV for an assumed photon index of 2.0. On the other hand, we do find evidence in the XMM-Newton data for a line-like emission feature at 6.4 keV from localized regions, again confirming earlier Suzaku measurements. We discuss the findings in the context of the origin of the observed γ-ray emission. Although neither hadronic nor leptonic scenarios can be fully ruled out, the observed line emission can be interpreted as the result of interactions between lower-energy (~ MeV) cosmic-ray protons with high gas-density regions in and around HESS J1534-571, and thus potentially be associated with particles accelerated in the SNR.

Investigation for the movement of the laser entrance hole and bubble plasmas in laser-driven hohlraum

In indirect-drive hohlraum, the heated plasmas from the laser entrance hole (LEH) and bubbles blow radially inward with time, which plays an important role in the evolution of hohlraum plasmas. Previously, the boundary of the LEH and bubble plasmas is measured using time-integrated x-ray images or x-ray images at several discrete moments. A new experiment is conducted to study the continuous temporal behaviors of the LEH and bubble plasmas, which utilizes a gas-filled hohlraum truncated on one side. Compared experiments are performed with 3 different LEH diameters (1.0 mm, 1.2 mm, and 1.4 mm). An x-ray streak camera (XSC) is employed for the first time to diagnose the continuous temporal x-ray images of the LEH and bubble plasmas, which are also measured by an x-ray framing camera (XFC) at several discrete moments. The XSC and the XFC are combined for the first time and give coincident results for the movement of the LEH and bubble plasmas. In addition, 2 sets of flat-response x-ray diode (FXRD) measure the total x-ray flux from both the LEH and the open end and thus give the radiation temperature (Tr) in the hohlraum. The Tr from the LEH end shows a visual increase compared with that from the open end, due to the LEH closure, which is coincident with the temporal x-ray images. This work presents more precise and detailed description for the continuous movement of the LEH and bubble plasmas, which is beneficial to optimize our radiation hydrodynamic code and hohlraum design for ignition.

Thermal emission from bow shocks

The nearby, massive, runaway star ζ Ophiuchi has a large bow shock detected in optical and infrared light and, uniquely among runaway O stars, diffuse X-ray emission detected from the shocked stellar wind. Here we make the first detailed computational investigation of the bow shock of ζ Ophiuchi, to test whether a simple model of the bow shock can explain the observed nebula, and to compare the detected X-ray emission with simulated emission maps. We reanalysed archival Chandra observations of the thermal diffuse X-ray emission from the shocked wind region of the bow shock, finding total unabsorbed X-ray flux in the 0.3–2keV band corresponding to a diffuse X-ray luminosity of LX = 2.33−1.54+1.12 × 1029 erg s−1, consistent with previous work. The diffuse X-ray emission arises from the region between the star and the bow shock. Three-dimensional magnetohydrodyanmic simulations were used to model the interaction of the star’s wind with a uniform interstellar medium (ISM) using a range of stellar and ISM parameters motivated by observational constraints. Synthetic infrared, Hα, soft X-ray, emission measure, and radio 6 GHz emission maps were generated from three simulations, for comparison with the relevant observations. Simulations where the space velocity of ζ Ophiuchi has a significant radial velocity produce infrared emission maps with the opening angle of the bow shock in better agreement with observations than for the case where motion is fully in the plane of the sky. All three simulations presented here have X-ray emission fainter than observed, in contrast to results for NGC 7635. The simulation with the highest pressure has the closest match to X-ray observations, with a flux level within a factor of two of the observational lower limit, and emission weighted temperature of log10(TA/K) = 6.4, although the morphology of the diffuse emission appears somewhat different. The observed X-ray emission is from a filled bubble that is brightest near the star, whereas simulations predict brightening towards the contact discontinuity as density increases. This first numerical study of the bow shock and wind bubble around ζ Ophiuchi uses a relatively simple model of a uniform ISM and ideal-magnetohydrodynamics, and can be used as a basis for comparing results from models incorporating more physical processes, or higher resolution simulations that may show more turbulent mixing.

Solar Soft X-ray Irradiance Variability, I: Segmentation of Hinode/XRT Full-Disk Images and Comparison with GOES (1 – 8 Å) X-Ray Flux

It is of great interest and importance to study the variabilities of solar EUV, UV and X-ray irradiance in heliophysics, in Earth’s climate, and space weather applications. A careful study is required to identify, track, monitor and segment the different coronal features such as active regions (ARs), coronal holes (CHs), the background regions (BGs) and the X-ray bright points (XBPs) from spatially resolved full-disk images of the Sun. Variability of solar soft X-ray irradiance is studied for a period of 13 years (February 2007–March 2020, covers Solar Cycle 24), using the X-Ray Telescope on board the Hinode (Hinode/XRT) and GOES (1 – 8 Å). The full-disk X-ray images observed in Al_mesh filter from XRT are used, for the first time, to understand the solar X-ray irradiance variability measured, Sun as a star, by GOES instrument. An algorithm in Python has been developed and applied to identify and segment coronal X-ray features (ARs, CHs, BGs, and XBPs) from the full-disk soft X-ray observations of Hinode/XRT. The segmentation process has been carried out automatically based on the intensity level, morphology and sizes of the X-ray features. The total intensity, area, and contribution of ARs/CHs/BGs/XBPs features were estimated and compared with the full-disk integrated intensity (FDI) and GOES (1 – 8 Å) X-ray irradiance measurements. The XBPs have been identified and counted automatically over the full disk to investigate their relation to solar magnetic cycle. The total intensity of ARs/CHs/BGs/XBPs/FD regions are compared with the GOES (1 – 8 Å) X-ray irradiance variations. We present the results obtained from Hinode/XRT full-disk images (in Al_mesh filter) and compare the resulting integrated full-disk intensity (FDI) with GOES X-ray irradiance. The X-ray intensity measured over ARs/CHs/BGs/XBPs/FD is well correlated with GOES X-ray flux. The contributions of the segmented X-ray features to FDI and X-ray irradiance variations are determined. It is found that the background and active regions have a greater impact on the X-ray irradiance fluctuations. The mean contribution estimated for the whole observed period of the background regions (BGs) will be around \(65\pm10.97\%\), whereas the ARs, XBPs and CHs are \(30\pm11.82\%\), \(4\pm1.18\%\) and \(1\pm0.52\%\), respectively, to total solar X-ray flux. We observed that the area and contribution of ARs and CHs varies with the phase of the solar cycle, whereas the BGs and XBPs show an anti-correlation. We find that the area of the coronal features is highly variable suggesting that their area has to be taken into account in irradiance models, in addition to their intensity variations. The time series results of XBPs suggest for an existence of anti-correlation between the number of XBPs and the sunspot numbers. It is also important to consider both the number variation and the contribution of XBPs in the reconstruction of total solar X-ray irradiance variability.

Accretion flow properties of XTE J1118+480 during its 2005 outburst

We study spectral and temporal properties of Galactic short orbital period transient black hole XTE J1118+480 during its 2005 outburst using archival data of RXTE PCA and HEXTE instruments in the combined energy range of 3 – 100 keV. Spectral analysis with the physical two component advective flow (TCAF) model allows us to understand the accretion flow properties of the source. We found that this outburst of XTE J1118+480 is an unconventional outburst as the source was only in the hard state (HS). Our spectral analysis suggests that during the entire outburst, the source was highly dominated by the low angular momentum sub-Keplerian halo rate. Since the source was active in radio throughout the outburst, we make an effort to estimate X-ray contribution of jets to total observed X-ray emissions from the spectral analysis with the TCAF model. The total X-ray intensity shows a similar nature of evolution as that of radio and jet X-ray fluxes. This allowed us to define this ‘outburst’ also as a jet dominated ‘outburst’. Total X-ray flux is also found to subside when jet activity disappears. Our detailed spectral analysis also indicated that although the source was only in the HS during the outburst, in the late declining phase the spectrum became slightly softer due to the slow rise in the Keplerian disk rate.

Extended X-ray emission from the z = 4.26 radio galaxy 4C 63.20

ABSTRACT We report on deep Chandra X-ray Telescope imaging observations of 4C 63.20, one of the few known radio galaxies at z > 3.5. The X-ray counterpart is resolved into a core plus two off-nuclear sources that (combined) account for close to 30 per cent of the total X-ray flux. Their morphology and orientation are consistent with a diffuse, lobe-like nature, albeit compact hotspots cannot be ruled out. The broad-band spectral energy distribution of 4C 63.20 can be reproduced with a jet model where the majority of the radio flux can be ascribed to synchrotron emission from the hotspots, whereas the (non-nuclear) X-ray emission is produced via inverse Compton (IC) off of cosmic microwave background (CMB) photons within the extended lobes. This scenario is broadly consistent with the expectation from highly magnetized lobes in a hotter CMB, and supports the view that IC/CMB may quench less extreme radio lobes at high redshifts.

Inference on disk-jet connection of MAXI J1836–194 from spectral analysis with the TCAF solution

Galactic transient black hole candidate (BHC) MAXI J1836–194 was discovered on 2011 Aug 30, by MAXI/GSC and Swift/BAT. The source activity during this outburst continued for ∼ 3 months before entering into the quiescent state. It again became active in March 2012 and continued for another ∼ 2 months. In this paper, 3 – 25 keV RXTE/PCA spectra from the 2011 outburst and 0.5 – 10.0 keV Swift/XRT data during its 2012 outburst are analyzed with the two-component advective flow (TCAF) model based fits files in XSPEC. We calculate the X-ray contributions coming from jets/outflow using a newly developed method based on the deviation of the TCAF model normalization. We also study the correlation between observed radio and estimated jet X-ray fluxes. The correlation indices (b) are found to be 1.79 and 0.61, when the 7.45GHz Very Large Array (VLA) radio flux is correlated with the total X-ray and jet X-ray fluxes in 3 – 25 keV range respectively. It has been found that the jet contributes in X-rays up to a maximum of 86% during its 2011 outburst. This makes the BHC MAXI J1836–194 strongly jet dominated during the initial rising phase.

NICER observations of the Crab pulsar glitch of 2017 November

Context. The Crab pulsar underwent its largest timing glitch on 2017 Nov. 8. The event was discovered at radio wavelengths, and was followed at soft X-ray energies by observatories, such as XPNAV and NICER. Aims. This work aims to compare the glitch behavior at the two wavelengths mentioned above. Preliminary work in this regard has been done by the X-ray satellite XPNAV. NICER with its far superior sensitivity is expected to reveal much more detailed behavior. Methods. NICER has accumulated more than 301 kilo seconds of data on the Crab pulsar, equivalent to more than 3.3 billion soft X-ray photons. These data were first processed using the standard NICER analysis pipeline. Then the arrival times of the X-ray photons were referred to the solar system’s barycenter. Then specific analysis was done to study the specific behavior outlined in the following sections, while taking dead time into account. Results. The variation of the rotation frequency of the Crab pulsar and its time derivative during the glitch is almost exactly similar at the radio and X-ray energies. The following properties of the Crab pulsar remain essentially constant before and after the glitch: the total X-ray flux; the flux, widths, and peaks of the two components of its integrated profile; and the soft X-ray spectrum. There is no evidence for giant pulses at X-ray energies. However, the timing noise of the Crab pulsar shows quasi sinusoidal variation before the glitch, with increasing amplitude, which is absent after the glitch. Conclusions. Even the strongest glitch in the Crab pulsar appears not to affect all but one of the properties mentioned above, at either frequency. The fact that the timing noise appears to change due to the glitch is an important clue to unravel as this is still an unexplained phenomenon.

The Sub-Neptune Desert and Its Dependence on Stellar Type: Controlled by Lifetime X-Ray Irradiation

Abstract Short-period sub-Neptunes with substantial volatile envelopes are among the most common type of known exoplanets. However, recent studies of the Kepler population have suggested a dearth of sub-Neptunes on highly irradiated orbits, where they are vulnerable to atmospheric photoevaporation. Physically, we expect this “photoevaporation desert” to depend on the total lifetime X-ray and extreme ultraviolet flux, the main drivers of atmospheric escape. In this work, we study the demographics of sub-Neptunes as a function of lifetime exposure to high-energy radiation and host-star mass. We find that for a given present-day insolation, planets orbiting a 0.3 M ⊙ star experience ∼100× more X-ray flux over their lifetimes versus a 1.2 M ⊙ star. Defining the photoevaporation desert as a region consistent with zero occurrence at 2σ, the onset of the desert happens for integrated X-ray fluxes greater than 1.43 × 1022 to 8.23 × 1020 as a function of planetary radii for 1.8–4 R ⊕. We also compare the location of the photoevaporation desert for different stellar types. We find much greater variability in the desert onset in the bolometric flux space compared to the integrated X-ray flux space, suggestive of photoevaporation driven by steady-state stellar X-ray emissions as the dominant control on desert location. Finally, we report tentative evidence for the sub-Neptune valley, first seen around Sun-like stars, for M&K dwarfs. The discovery of additional planets around low-mass stars from surveys such as the Transiting Exoplanet Survey Satellite mission will enable detailed exploration of these trends.

Experimental and simulation studies on radiative properties of uranium planar target coated with an ultrathin aluminum layer

An ultrathin aluminum (Al) layer is proposed to be coated on the surface of the uranium (U) planar target for preventing the oxidization of U and optimizing the hard x-ray spectrum. Comparative experiments using several planar targets with different materials are implemented on the Shenguang-III prototype laser facility to study their radiative properties. Under the laser intensity of W cm−2, we observe that the U target coated with 30 nm thick Al produces almost the same peak intensity of the total x-ray flux and decreases the hard x-ray fraction by 38.5% compared to the U target coated with 100 nm thick gold. Simulations using XRL2D (2D radiation hydrodynamic code) interpret the measured results and indicate that the radiative property of Al-coated U approaches that of pure U, which theoretically has a high laser to x-ray conversion efficiency and a quasi-Planckian spectrum. Based on our analysis, Al-coated U is a promising material of the ignition hohlraum and should have many applications in high energy density physics.

The contribution of the albedo for photons to the intensity of hard X-ray emission of solar flares

The albedo contribution to the total hard X-ray solar-flare emission has been considered. First, the distribution of primary hard X-ray photons localized along the flare loop was found, and finally, the Monte Carlo calculations of the Compton scattered hard X-ray photons were performed. The albedo for photons was shown to contribute to the total X-ray flux only in the energy range from 30 to 100 keV. The backscattered photon flux depends on the loop's position and on the localization of the source of primary radiation along the loop. For an isotropic distribution of primary photons, the backscattered photons’ contribution to the total flux is maximal for the loop in the center of the Sun and reduces when shifting to a limb. In the case of an anisotropic source the angle at which the contribution is maximal depends on the degree of anisotropy and on X-ray directivity in the source.

Synchrotron radiation X-ray in-line phase-contrast imaging with highly symmetric source

In available synchrotron radiation facilities all over the world, the size of electron beam bunch has distinct difference between the horizontal direction and the vertical direction at the cross section vertical to electron moving direction. It will cause low symmetry of source size in horizontal and vertical directions, and result in big difference in the spacial resolution and phase contrast between these two directions in synchrotron radiation X-ray in-line phase contrast imaging. The superior resolution and phase contrast of one direction will couple with the inferior ones of the other direction in actual object imaging, this interaction will degrade both spacial resolution and phase contrast of the whole image and lead to poor image quality. In this paper, a four-knife white beam slit is used in Beijing synchrotron radiation facility (BSRF) 4W1A beamline to adjust source size in horizontal and vertical directions and restrict the point spread function (PSF) of source, the source size is limited from 1.23 mm (horizontal)×0.46 mm (vertical) to 0.35 mm×0.35 mm. By this way, a highly symmetric effective X-ray source is obtained. The symmetry of source size is improved from 2.7 to about 1. Although the total X-ray flux loses 99.95%, the X-ray flux density is only reduced to 22%. It because total flux is taken account of the expanded spot size due to divergence, while flux density is mainly related to effective source size, which is limited not severely as expanded spot size by white beam slit. The flux density reduction by this method is not a critical defect in high resolution X-ray phase contrast imaging and can be improved by other ways. The polyamide fiber net is imaged using X-ray in-line phase contrast imaging at 4W1A, BSRF. Diameter of fiber is about 50 microns, X-ray energy is 13 keV, the effective pixel size is 0.325 micron, the experiment images are obtained at object-to-detector distances of 4, 10, 16, 36, 100, 200 and 300 mm with source-to-object distance of about 43 m. The results show that when source size in horizontal direction is limited from 1.23 to 0.35 mm (symmetry of source size is about 1 at this condition), the maximal phase contrast of image is advanced from 0.057 to 0.35. It means the density sensitivity is promoted about 5 times than in ordinary source size conditions. The spacial resolutions in different source size symmetry conditions are also primary analyzed based on Rayleigh criterion. The result shows that spacial resolution can be improved notably in horizontal direction by limiting horizontal source size to a nearly symmetric source size condition. Our work demonstrates that the spacial resolution and phase contrast can be promoted at the same level by source size symmetry improved, which markedly improved the imaging quality in synchrotron radiation X-ray in-line phase-contrast imaging. It will have great benefit to high-resolution X-ray in-line phase contrast imaging. The reasons of these improvements are analyzed and developments in future are also discussed.

Expansion measurements of supernova remnant RX J1713.7−3946

Abstract Supernova remnant (SNR) RX J1713.7−3946 is well known for its bright TeV gamma-ray emission with a shell-like morphology. Strong synchrotron X-ray emission dominates the total X-ray flux in SNR RX J1713.7−3946 and the X-ray morphology is broadly similar to the TeV gamma-ray appearance. The synchrotron X-ray and TeV gamma-ray brightness allows us to perform detailed analysis of the acceleration of TeV-scale particles in this SNR. To constrain the hydrodynamical evolution of RX J1713.7−3946, we have performed six observations of the northwestern (NW) shell with the Chandra X-ray Observatory from 2005 to 2011, and measured the proper motion by using these data and the first epoch observation taken in 2000. The blast-wave shock speed at the NW shell is measured to be (3900 ± 300)(d/ kpc) km s−1 with an estimated distance of d = 1 kpc, and the proper motions of other structures within the NW shell are significantly less than that. Assuming that the measured blast-wave shock speed is representative of the remnant's outer shock wave as a whole, we have confronted our measurements, as well as a recent detection of thermal X-ray lines, with the analytic solution of the hydrodynamical properties of SNRs. Our hydrodynamical analysis indicates that the age of the remnant is 1580–2100 yr, supporting the association with SN393. A model with supernova kinetic energy of E = 1051 erg, ejecta mass of Mej = 3 M⊙, and ambient density at the current blast wave location of n2 = 0.015 cm−3, provides a reasonable explanation for our measurements and previous findings at the X-ray and gamma-ray wavelengths. We find that the transition to the Sedov–Taylor phase is incomplete for any reasonable set of parameters, implying that the current maximum energy of accelerated protons in RX J1713.7−3946 would not correspond to the maximum attainable energy for this remnant.

Multiple angle measurement and modeling of M-band x-ray fluxes from vacuum hohlraum

The energetics experiment of vacuum gold hohlraums is implemented on the Shenguang-II laser facility. The total and M-band x-ray fluxes from the laser entrance holes are measured by the flat response x-ray diodes which are set at multiple angles with respect to the axis of the hohlraums. The measured M-band fractions are from 5.72% to 7.71%, which present a specific angular distribution. Based on the fact that the M-band x-rays are mainly emitted from the under-dense high-temperature plasmas, a simplified model is developed to give a quantitative prediction of the intensity, temporal behavior, and angular distribution of the M-band x-ray flux. The results obtained with our model are in good agreement with the experimental data, showing that our model can be a useful tool for M-band x-ray investigation.

Single-pulse x-ray diffraction using polycapillary optics for in situ dynamic diffraction.

Diagnostic use of single-pulse x-ray diffraction (XRD) at pulsed power facilities can be challenging due to factors such as the high flux and brightness requirements for diffraction and the geometric constraints of experimental platforms. By necessity, the x-ray source is usually positioned very close, within a few inches of the sample. On dynamic compression platforms, this puts the x-ray source in the debris field. We coupled x-ray polycapillary optics to a single-shot needle-and-washer x-ray diode source using a laser-based alignment scheme to obtain high-quality x-ray diffraction using a single 16 ns x-ray pulse with the source >1 m from the sample. The system was tested on a Mo sample in reflection geometry using 17 keV x-rays from a Mo anode. We also identified an anode conditioning effect that increased the x-ray intensity by 180%. Quantitative measurements of the x-ray focal spot produced by the polycapillary yielded a total x-ray flux on the sample of 3.3 ± 0.5 × 10(7) molybdenum Kα photons.

Synoptic and fast events on the sun according to observations at the center and wings of the Ca II K line at the Kislovodsk Mountain station patrol telescope

Observations performed at the solar telescope–spectroheliograph, which has continuously automatically operated at MAS MAO RAS, were analyzed. Measurements of the activity index in the Ca II K line, which were performed according to the program of synoptic observations, are presented. The development of the solar flares observed at the center and on the wings of the Ca II K line was compared with observations in the X-ray and radio bands. It was shown that the time variations in the intensity in the 1–8 A range according to the Geostationary Orbiting Environmental Satellites’ (GOES) data and in the Ca II K line are close to each other and that the total X-ray flux and Ca II K intensity amplitude substantially correlate during the entire flare.

Uranium hohlraum with an ultrathin uranium–nitride coating layer for low hard x-ray emission and high radiation temperature

An ultrathin layer of uranium nitrides (UN) has been coated on the inner surface of depleted uranium hohlraum (DUH), which has been proven by our experiment to prevent the oxidization of uranium (U) effectively. Comparative experiments between the novel depleted uranium hohlraum and pure golden (Au) hohlraum are implemented on an SGIII-prototype laser facility. Under a laser intensity of 6 × 1014 W cm−2, we observe that the hard x-ray (hν keV) fraction of the uranium hohlraum decreases by 61% and the peak intensity of the total x-ray flux (0.1 keV∼5.0 keV) increases by 5%. Radiation hydrodynamic code LARED is used to interpret the above observations. Our result for the first time indicates the advantages of the UN-coated DUH in generating a uniform x-ray source with a quasi-Planckian spectrum, which should have important applications in high energy density physics.