Pulsed X-ray Radiation Research Articles

Comparison of methods for changing the spectrum of radiation of a pulse x-ray source to determine the most effective two-energy image processing

For detecting substances with similar chemical composition and density, one of the promising methods of non-destructive testing is dual-energy processing of X-ray images. In particular, dual-energy transformation algorithms can be used to search for minerals hidden within barren rock. This method is most effective when the conditions for registering X-ray images and energy levels are properly selected. This study compares the effectiveness of image processing using the dual-energy method for three cases of spectral composition variation: firstly, as a result of adjusting the voltage on the X-ray tube; secondly, by attenuating low-energy radiation through the use of a copper filter; and thirdly, by combining these two methods. Beryl particles embedded in ground muscovite are used as samples for detection. The study utilizes a pulsed X-ray radiation source that generates radiation pulses of nanosecond duration. An original high-voltage generator scheme has been implemented for the method of regulating radiation energy by changing the peak voltage on the X-ray tube. The use of X-ray sources of this type enables the acquisition of high-resolution X-ray images of moving objects.

Generation of Superhard X-Ray Radiation at The Compressing of Aluminum Wire Arrays

At the S-300 generator (2 MA, 400 kV, 100 ns), the appearance of superhard X-ray radiation was observed during magnetic compression of cylindrical nested aluminum arrays with a linear mass of ~350 μg/cm, consisting of aluminum wires with a diameter of 15 μm. At the final compression phase of the arrays, a compact pinch is formed, consisting of a large number of hot spots located along the axis. This phase is accompanied by the emission of soft X-rays with a duration of ~10 ns. Simultaneously with the pulses of soft X-ray radiation, superhard X-ray radiation with an energy exceeding 450 keV was discovered. Superhard X-ray radiation was measured with shielded scintillation detectors with lead filters 20–70 mm thick. The main cause of overvoltage on the plasma column appears to be constriction instability.

Expansion and Spectral Softening of the Dust-scattering Rings of GRB 221009A

An expanding X-ray halo or rings appear when short pulses of X-ray radiation from a background source are scattered by clouds of dust in the Milky Way. We study the X-ray rings of the brightest gamma-ray burst (GRB) 221009A, detected by the Swift X-Ray Telescope. The rings center on the GRB position, and their angular radii increase with time. We identify five major expanding rings, and our modeling of their expansion history suggests that they are scattered off from five dusty clouds at distances of 0.4–13 kpc from the observer. Given an assumed prompt X-ray fluence of this GRB, the fluxes of those rings suggest that these clouds have dust grain column densities of 107∼8 cm−2. More interestingly, our time-dependent spectral analysis of these rings shows that they all experience spectral softening, i.e., getting softer as they expand, with spectral indices ranging from 2.2 to 5, consistent with what the dust-scattering model predicts.

Time-Dependent Resonant Inelastic X-ray Scattering of Pyrazine at the Nitrogen K-Edge: A Quantum Dynamics Approach.

We calculate resonant inelastic X-ray scattering spectra of pyrazine at the nitrogen K-edge in the time domain including wavepacket dynamics in both the valence and core-excited state manifolds. Upon resonant excitation, we observe ultrafast non-adiabatic population transfer between core-excited states within the core-hole lifetime, leading to molecular symmetry distortions. Importantly, our time-domain approach inherently contains the ability to manipulate the dynamics of this process by detuning the excitation energy, which effectively shortens the scattering duration. We also explore the impact of pulsed incident X-ray radiation, which provides a foundation for state-of-the-art time-resolved experiments with coherent pulsed light sources.

Investigation on the scaling of magneto-Rayleigh–Taylor instability to the current rise time of Z-pinch plasmas

Understanding how the magneto-Rayleigh–Taylor instability (MRTI) scales to the current rise time is vital for Z-pinch dynamic hohlraum driven inertial confinement fusion. Wang et al discovered in prior theoretical work that the perturbation amplitude of MRTI before stagnation increases linearly with the current rise time when the implosion velocity of Z-pinch plasma is held constant. In the present work, three types of wire-array experiments with similar implosion dynamics and constant implosion velocity are performed on an 8 MA pulse power generator to investigate the scaling of MRTI to the rise time. It is successfully accomplished for the first time to obtain the similar wire-array Z-pinch implosions in which the current rise time is scaled up to three times on the generator by controlling the trigger time of its 24 modules. Both the experimental results, which include x-ray radiation pulses and x-ray images of imploding plasmas, and the related numerical analysis have shown that the MRTI before stagnation grows linearly with the rise time, as predicted by the theoretical model.

Arcing in ambient air triggered by pulsed x-ray radiation

The generation of arcs in air at atmospheric pressure induced by static voltage and triggered by x-ray pulses is analyzed. A static voltage is set between a cathode and an anode, and the arcing process is triggered by irradiating the air gap of a pin-to-plane switch with an x-ray photon pulse in the MeV range. This x-ray pulse produces a weakly ionized non-equilibrium air plasma (called the pre-plasma), which reduces the breakdown threshold. The influence of this pulsed x-ray on the arcing process is analyzed. The reduction of the breakdown voltage has been quantified, and for low static voltages, the creation of a sheath that is responsible for a delay in the arcing process is highlighted. Electrical measurements (currents and voltages) and optical emission spectroscopy have been performed to characterize the arcs in terms of electron density, temperature, and electric conductivity. A good agreement between measurements and 3D Maxwell calculations is achieved, which allows us to determine the electric conductivity of the arc in both self-triggered and x-ray-triggered regimes.

An active dose-measuring device for X-rays generated by ultra-short, ultra-intense laser pulses

Ultra-short, ultra-intense laser pulses can create extreme physical conditions for a wide range of applications in atomic and molecular physics, materials chemistry, and inertial-confinement fusion. However, laser-matter interactions can be accompanied by significant X-ray emission that introduces radiation risks to the nearby environment and personnel. It is usually to monitor the radiation dose during in high-intensity laser-target interactions with optically stimulated luminescence and thermo-luminescence devices. However, these passive methods cannot measure the radiation dose in real time, while most active dosimeters cannot accurately measure pulsed radiation doses. Here, transient pulse X-ray radiation doses are converted by CdWO4 crystals into slow signals. Because the crystals have a 14-μs luminescence decay time, they can absorb sub-nanosecond X-ray pulses and release the energy at a 100-μs rate, thus reducing the linear-response pressure of subsequent devices. A pulse detector based on a CdWO4 crystal, a phototube, and a custom signal-processing circuit was developed. Experiments were performed at the 45-TW femtosecond laser facility of the Laser Fusion Research Center. The detector deviation was less than ±20% relative to that of an ionization-chamber detector. This initially verified its feasibility for real-time pulsed X-ray radiation detection.

Extended x-ray absorption fine structure measurement of ramp compressed Ti using laser-irradiated metallic foil as x-ray source on SGIII prototype laser facility

Laser-irradiated metallic foils were considered as x-ray sources for extended x-ray absorption fine structure (EXAFS) measurements and confirmed by experiments on the SGIII prototype facility. The Au foils were irradiated by laser beams with a total energy of 2.77 kJ and full width at half maximum (FWHM) of 1 ns to create an x-ray source. The x-ray emission was spectrally smooth in the energy range of Ti EXAFS, the FWHM of Au foil x-ray radiation pulse in the energy range of 0.1–4000 eV was 0.99 ns, and the FWHM of x-ray pulse in the energy range of 5000–6000 eV was deduced to be 0.55 ns according to simulation results. A shaped laser pulse was designed to achieve the Ti sample’s laser-direct-driven ramp compression process. By creating a quasi-stable state lasting longer than 1 ns as the probing window during the compression process, the demand for temporal resolution was reduced. EXAFS spectra of compressed Ti in α and ω-phase were obtained and compared, and structural phase transition was verified by EXAFS pattern changes. The velocity of the back interface of the Ti sample was measured by the velocity interferometer system for any reflector, and the maximum of the deduced pressure in the middle of the Ti sample was 8.2 GPa, which is consistent with the α-ω phase transition.

Studies into the Spectra of Pulsed X-Ray Radiation of Hybrid X-Pinch Plasma

Studies into the Spectra of Pulsed X-Ray Radiation of Hybrid X-Pinch Plasma

Влияние состояния рабочей поверхности гальванического датчика импульсного рентгеновского излучения на его быстродействие

A new design of a galvanic sensor of pulsed X-ray radiation is proposed, which is a flat electric capacitor with a window in one metal lining and a solid dielectric made of the single crystal sapphire with a thickness of 200-300 µm inside. The influence of the surface roughness of the sapphire in the window area on the galvanic linear sensor of X-ray radiation has been established. Tests have shown that with ultra-smooth polishing of the sapphire plate working surface in the window area to a roughness of Rq≤ 0.2 nm, it is possible to provide the galvanic linear detection of X-rays with an energy in the range of 0.1-1 keV and a power density of 1-2 MW•cm-2 with a sensor response time of about 8 ns. Sensors of this type can be used in studies of inertial nuclear fusion processes

Influence of the working surface roughness of the pulsed X-ray radiation galvanic sensor on its performance

A new design of a galvanic sensor of pulsed X-ray radiation is proposed, which is a flat electric capacitor with a window in one metal lining and a solid dielectric made of a single-crystal sapphire with a thickness of 200-300 μm inside. The influence of the surface roughness of the sapphire in the window area on the galvanic linear sensor of X-ray radiation has been established. Tests have shown that, with ultra-smooth polishing of the sapphire plate working surface in the window area to a roughness of Rq≤ 0.2 nm, it is possible to provide the galvanic linear detection of X-rays with an energy in the range of 0.1-1 keV and power density of 1-2 MW· cm-2 with a sensor response time of about 8 ns. Sensors of this type can be used in studies of inertial nuclear fusion processes. Keywords: X-ray radiation, galvanic sensor, sapphire, dielectric, flat capacitor.

Isolated ultra-bright attosecond pulses via non-collinear gating

When light with relativistic intensity is incident on a solid target, bright attosecond pulses of extreme ultraviolet and x-ray radiation can be generated in the reflected beam. Unfortunately, the use of multi-cycle laser pulses results in trains of these attosecond pulses. Here we investigate a non-collinear gating scheme applied to surface high-harmonic generation to allow for the extraction of a single intense attosecond pulse from this train. Using 3D and 2D particle in cell (PIC) simulations we demonstrate that it is possible to angularly isolate a single attosecond pulse from the main driving laser pulse using this interaction geometry with intensities I > 1020 W cm−2. This result opens the door to generating bright attosecond pulses from relativistic plasmas without the need to spectrally filter the driving laser pulse.

Lattice design for an improved angular dispersion-induced microbunching scheme

In this paper, an improved angular dispersion-induced microbunching (ADM) scheme [1] is studied to generate fully coherent soft x-ray radiation pulses in an electron storage ring light source with a limited energy modulation amplitude. This scheme releases the coupling between the dispersion function and the momentum compaction in the original ADM scheme. The lattice structure of the improved ADM is simple, which only adds a chicane following the dogleg compared to the original one. With the chicane, even higher harmonic radiation can be generated. Numerical simulation results show that soft x-ray radiation with photon energy covering the water window range can be produced.

X-Ray Filter with Variable Transmission for Experiments on the Action of a Multi-Terawatt Pulse of Soft X-Ray Radiation on Targets

X-Ray Filter with Variable Transmission for Experiments on the Action of a Multi-Terawatt Pulse of Soft X-Ray Radiation on Targets

Synchronised TeraHertz Radiation and Soft X-rays Produced in a FEL Oscillator

We present a scheme to generate synchronised THz and soft X-ray radiation pulses by using a free-electron laser oscillator driven by a high repetition rate (of order 10–100 MHz) energy recovery linac. The backward THz radiation in the oscillator cavity interacts with a successive electron bunch, thus producing few 105 soft/hard X-ray photons per shot (namely 1012–1013 photons/s) via Thomson/Compton back-scattering, synchronised with the mJ-class THz pulse within the temporal jitter of electron beams accelerated in the superconducting cavities of the linac (less than 100 fs). Detailed simulations have been performed in order to assess the capability of the scheme for typical wavelengths of interest, between 10 and 50 μm for the TeraHertz radiation and 0.5–3 nm for the X-rays.

Synthesis and Characterization of Hybrid Lipid Nanoparticles Containing Gold Nanoparticles and a Weak Base Drug.

Hybrid lipid nanoparticles containing gold nanoparticles (LNP-GNPs) and drugs have potential for imaging applications as well as triggered release of LNP contents in response to pulsed laser or X-ray radiation mediated by the GNPs. However, methods to synthesize LNP-GNP systems that efficiently entrap GNPs (the potential triggered release and imaging agent) and then load and retain the drug cargo in a manner that may have clinical applications have proven elusive. Here, we develop a straightforward "bottom-up" approach to manufacture drug-loaded LNP-GNP systems. We show that negatively charged GNPs of 5 nm diameter can be stably loaded into LNPs containing 10 mol % ionizable cationic lipid using an ethanol dilution, rapid mixing approach and that these systems also exhibit aqueous compartments. Further, we show that such systems can also entrap ammonium sulfate, enabling pH-dependent loading of the weak base anti-cancer drug doxorubicin into the aqueous compartments. Cryo-transmission electron microscopy (Cryo-TEM) imaging clearly demonstrates the presence of GNPs in the interior of the resulting hybrid nanostructures as well as the formation of electron-dense drug precipitates in the aqueous core of the LNP-GNPs. The approach described here is a robust and straightforward method to generate hybrid LNP-GNP-drug and other LNP-metal nanoparticle-drug systems with potential applications for a variety of triggered release protocols.

Establishment of pulsed X-ray reference radiation field and measurement of related parameters

The international research on radiation protection dosimetry mainly focuses on continuous radiation. However, pulsed radiation has been widely used in the fields of new detector development, radiographic inspection, X-ray diagnosis, nuclear accident emergency and scientific research, the measurement of pulsed dose (rate) is very difficult. In order to solve the technical problem of pulse response test of active radiation dosimeter, the generation principle of pulsed X-ray and gamma ray radiation field is discussed, and the reference radiation field of pulsed X-ray is established based on three kinds of X-ray machines. Combined with the transfer ionization chamber and pulse width measurement system, the research of pulsed radiation dose (rate) measurement technology is carried out. The experimental results show that the pulse width of the established pulsed X-ray reference radiation field can be adjusted between 50 ns and 10 s, and the instantaneous dose rate range is 2.5 mSv/h-6.7 × 105 Sv/h, which can be widely used to study the pulsed X-ray response characteristics of active radiation dosimeter. This work can be widely used to study the pulsed X-ray response characteristics of active radiation dosimeter, which is of great significance to solve the calibration problem of pulsed radiation dose monitoring instrument.

Progress in researching the implosion of nested arrays of mixed composition and the generation of soft x-ray power pulse

The results of experiments on the study of plasma compression of nested wire arrays of mixed composition and the generation of powerful pulses of soft x-ray radiation (SXR), carried out on a pulse power facility Angara-5-1 at a current level of up to 3 MA, are presented. Based on the latest experimental data on the intensity of plasma formation of various substances (in μg(cm2 ns)−1) (Mitrofanov et al 2020 Plasma Phys. Rep. 46 1150–80) and on the features of the dynamics of plasma compression in nested arrays (Mitrofanov et al 2018 Plasma Phys. Rep. 44 203–35), a nested wire array design has been developed which makes it possible to obtain a high peak SXR power in comparison with the known designs of single and nested tungsten wire arrays. During the implosion of nested arrays of mixed composition, consisting of plastic fibers and tungsten wires, shorter and more powerful SXR pulses were obtained with a maximum peak power P SXR max∼ 10 TW with a full width at half maximum (FWHM) duration of ∼5 ns compared to the parameters of SXR pulses upon compression of single tungsten arrays: P SXR max∼ 5 TW and FWHM ∼ 10 ns. Thus, under the conditions of our experiments, we have shown the possibility of a twofold increase in the peak SXR power during compression of nested arrays by optimizing their design.

Effect of pulsed soft X-ray radiation on the surface topography of some metals

Effect of the pulsed soft X-ray fluxes (PSXF) on the surface topography of metals (Mg and Cu) has been investigated. Soft pulse X-ray irradiation (energy quanta of 0.1-1.0 keV) were carried out on a high-current MIG generator. The sample of magnesium was located at a distance of 10 cm from the X-ray source. Since the distance to the sample significantly exceeded the size of the X-ray beam, it can be assumed that the density of the X-ray radiation flow to the magnesium sample was uniform. The duration of the radiation pulse was 100 ns, and the radiation energy density in the pulse varied from 13 to 19 J/cm2. As a result of melting under the action of PSXF of the near-surface layer of metals and subsequent solidification, a wavy relief is formed on their surface. Defects in the form of craters, which usually occur after the impact of a powerful pulsed ion flow on metals, were not detected.

Experiments for thermomechanical effects based on Z-pinch X-ray sources

Responses of materials and structures to intense pulsed X-ray radiation, such as thermal shock wave propagation and blowoff impulse generation are referred to collectively as X-ray thermomechanical effects, which have been applied to radiation hardening, astrophysics, and planetary science. Preliminary experiments for thermomechanical effects have been performed utilizing wire array Z-pinch X-ray sources on a pulsed power facility with a drive current of about 10 MA. A total X-ray radiation energy of about 230 kJ was produced by a nested aluminum wire array of 20 mm in outer diameter, and theK-shell yield of about 30 kJ for aluminum was measured. An X-ray energy fluence up to 732 J/cm2 was produced on an irradiated target which was positioned at 5 cm away from the X-ray source center. The irradiated target was an aluminum disk 2 mm in thickness and 10 mm in diameter, backed by an aluminum liner. The total weight of the disk and liner was 585 mg. An all-fiber photonic Doppler velocimeter (PDV) was used to monitor the motion of the rear surface of the irradiated target. The velocity history measured by PDV suggested a free-face velocity of 2.12 km/s when the shock wave arrived at the rear surface of the target, and the final velocity of the target is 180 m/s. Based on the Hugoniot relationships and the law of momentum conservation, a stress of the thermal shock wave of 19.2 GPa and a blowoff impulse per unit target area of 1341 Pa·s were deduced. Furthermore, a consequent coupling coefficient of 1.83 Pa·s·cm2/J was estimated from the measurements of blowoff impulse and the X-ray energy fluence. Finally, discussions on the reliability and uncertainty of the measurement were presented. These experimental results described here preliminarily validated the feasibility of the application of PDV to the research of X-ray thermomechanical effect.