Soft X-ray Source Research Articles

Impact of repetitive, ultra-short soft X-ray pulses from processing of steel with ultrafast lasers on human cell cultures

Ultrafast lasers, with pulse durations below a few picoseconds, are of significant interest to the industry, offering a cutting-edge approach to enhancing manufacturing processes and enabling the fabrication of intricate components with unparalleled accuracy. When processing metals at irradiances exceeding the evaporation threshold of about 1010 W/cm² these processes can generate ultra-short, soft X-ray pulses with photon energies above 5 keV. This has prompted extensive discussions and regulatory measures on radiation safety. However, the impact of these ultra-short X-ray pulses on molecular pathways in the context of living cells, has not been investigated so far. This paper presents the first molecular characterization of epithelial cell responses to ultra-short soft X-ray pulses, generated during processing of steel with an ultrafast laser. The laser provided pulses of 6.7 ps with a pulse repetition rate of 300 kHz and an average power of 500 W. The irradiance was 1.95 ×1013 W/cm2. Ambient exposure of vitro human cell cultures, followed by imaging of the DNA damage response and fitting of the data to a calibrated model for the absorbed dose, revealed a linear increase in the DNA damage response relative to the exposure dose. This is in line with findings from work using continuous wave soft X-ray sources and suggests that the ultra-short X-ray pulses do not generate additional hazard. This research contributes valuable insights into the biological effects of ultrafast laser processes and their potential implications for user safety.

The Rockets for Extended-source X-ray Spectroscopy Instrument Design

The Rockets for Extended-source X-ray Spectroscopy (tREXS) are a series of suborbital rocket payloads designed to collect spectral emission from extended astronomical sources of soft X-rays. The tREXS spectrograph uses mechanical beam-shaping modules and reflection gratings to passively focus and then disperse incident X-rays to an array of Teledyne/e2v CIS 113 CMOS X-ray sensors. Designed to achieve a moderate spectral resolution, R ⪆ 50, from ≈15 to 40 Å over a large field of view (>10 deg2), the tREXS instrument is sensitive to line emission from key ion species over the soft-X-ray band. Here we present the complete end-to-end design of the tREXS spectrograph and discuss its significance and expected performance, using simulated observations of the Cygnus Loop supernova remnant and an enhanced region in the soft X-ray background.

Effect of the geometrical parameters of an X-pinch on the characteristics of the soft x-ray source

Effect of the geometrical parameters of an X-pinch on the characteristics of the soft x-ray source

PEARLS: NuSTAR and XMM-Newton Extragalactic Survey of the JWST North Ecliptic Pole Time-domain Field II

We present the second NuSTAR and XMM-Newton extragalactic survey of the JWST north ecliptic pole (NEP) time-domain field (TDF). The first NuSTAR NEP-TDF survey had 681 ks total exposure time executed in NuSTAR cycle 5 in 2019 and 2020. This second survey, acquired from 2020 to 2022 in cycle 6, adds 880 ks of NuSTAR exposure time. The overall NuSTAR NEP-TDF survey is the most sensitive NuSTAR extragalactic survey to date, and a total of 60 sources were detected above the 95% reliability threshold. We constrain the hard X-ray number counts, logN – logS , down to 1.7 × 10−14 erg cm−2 s−1 at 8–24 keV and detect an excess of hard X-ray sources at the faint end. About 47% of the NuSTAR-detected sources are heavily obscured (N H > 1023 cm−2), and 18−8+20 % of the NuSTAR-detected sources are Compton-thick (N H > 1024 cm−2). These fractions are consistent with those measured in other NuSTAR surveys. Four sources presented >2σ variability in the 3 yr survey. In addition to NuSTAR, a total of 62 ks of XMM-Newton observations were taken during NuSTAR cycle 6. The XMM-Newton observations provide soft X-ray (0.5–10 keV) coverage in the same field and enable more robust identification of the visible and infrared counterparts of the NuSTAR-detected sources. A total of 286 soft X-ray sources were detected, out of which 214 XMM-Newton sources have secure counterparts from multiwavelength catalogs.

A soft and transient ultraluminous X-ray source with six-hour modulation in the NGC 300 galaxy

We investigate the nature of CXOU J005440.5−374320 (J0054), a peculiar bright (∼4 × 1039 erg s−1) and soft X-ray transient in the spiral galaxy NGC 300 with a six-hour periodic flux modulation that was detected in a 2014 Chandra observation. Subsequent observations with Chandra and XMM-Newton, as well as a large observational campaign of NGC 300 and its sources performed with the Swift Neil Gehrels Observatory, showed that this source exhibits recurrent flaring activity: four other outbursts were detected across ∼8 years of monitoring. Using data from the Swift/UVOT archive and from the XMM-Newton/OM and Gaia catalogues, we determined that the source is likely associated with a bright blue optical/ultraviolet counterpart. This prompted us to perform follow-up observations with the Southern African Large Telescope in December 2019. With the multi-wavelength information at hand, we discuss several possibilities for the nature of J0054. Although none is able to account for the full range of the observed peculiar features, we found that the two most promising scenarios are a stellar-mass compact object in a binary system with a Wolf–Rayet star companion, or the recurrent tidal stripping of a stellar object trapped in a system with an intermediate-mass (∼1000 M⊙) black hole.

Optimization of Parameters of a Compact Soft X-Ray Source for Operation in the Wavelength Range 2–5 nm

Optimization of Parameters of a Compact Soft X-Ray Source for Operation in the Wavelength Range 2–5 nm

Spectral Characteristics of Polarization Radiation in the Water Window Range

The high-intensity and monochromatic radiation sources in the water window spectral range are desirable for many applications. One of the potential candidates of soft X-ray sources is polarization radiation produced by a charged particle passing through a thin foil. In the soft X-ray range near the absorption edges of a target material, the real part of dielectric permittivity can exceed unity, and the Tamm–Frank criterion is fulfilled. Thus, two types of radiation are produced: transition and Cherenkov radiation. In this report, we theoretically investigated the spectral characteristics of radiation produced in both cases when the Tamm–Frank criterion is met or not met. We showed the dependences of the spectrum as a function of thickness and the incidence angle. To describe the properties of polarization radiation and the complex dielectric permittivity, the polarization current approach and Henke’s model were used, respectively.

Conceptual design of a super bend dipole magnet as a high-field source for the ILSF storage ring

The Iranian Light Source Facility (ILSF) is in the detailed design phase. It will operate at 3 GeV and 400 mA with an ultra-low horizontal emittance of 0.27 nm.rad. The main storage ring combined dipole magnet has a 0.56 T magnetic field and a -7 T/m gradient. It can serve as a soft X-ray source. There are several ways to achieve hard X-rays; one is to use a high-field dipole. It is designed with a permanent magnet and consists of three parts; a high field part that provides a 3 T magnetic field and two low field parts on either side of the high field one. The basic design of the super-bend dipole magnet is presented here.

Flux and estimated spectra from a low-intensity laser-driven X-ray source

Abstract Laser-driven X-rays as probes for high-energy-density physics spans an extremely large parameter space with laser intensities varying by 8 orders of magnitude. We have built and characterized a soft X-ray source driven by a modest intensity laser of 4 × 1013 W/cm2. Emitted X-rays were measured by diamond radiation detectors and a filtered soft X-ray camera. A material-dependence study on Al, Ti, stainless steel alloy 304, Fe, Cu and Sn targets indicated 5-μm-thick Cu foils produced the highest X-ray yield. X-ray emission in the laser direction and emission in the reverse direction depend strongly on the foil material and the thickness due to the opacity and hydrodynamic disassembly time. The time-varying X-ray signals are used to measure the material thinning rate and is found to be ∼1.5 μm/ns for the materials tested implying thermal temperature around 0.6 eV. The X-ray spectra from Cu targets peaks at ∼2 keV with no emission >4 keV and was estimated using images with eight different foil filters. One-dimensional hydrodynamic and spectral calculations using HELIOS-CR provide qualitative agreement with experimental results. Modest intensity lasers can be an excellent source for nanosecond bursts of soft X-rays.

Soft X-ray and FUV observations of Nova Her 2021 (V1674 Her) with AstroSat

ABSTRACT Nova Her 2021 or V1674 Her was one of the fastest novae to be observed so far. We report here the results from our timing and spectral studies of the source observed at multiple epochs with AstroSat. We report the detection of a periodicity in the source in soft X-rays at a period of 501.4–501.5 s which was detected with high significance after the peak of the super-soft phase, but was not detected in the far ultraviolet (FUV) band of AstroSat. The shape of the phase-folded X-ray light curves has varied significantly as the nova evolved. The phase-resolved spectral studies reveal the likely presence of various absorption features in the soft X-ray band of 0.5–2 keV, and suggest that the optical depth of these absorption features may be marginally dependent on the pulse phase. Strong emission lines from Si, N, and O are detected in the FUV, and their strength declined continuously as the nova evolved and went through a bright X-ray state.

Expansion of the Soft X-ray Source and “Magnetic Detonation” in Solar Flares

The detection of radio emission from solar flares at frequencies below ∼2 GHz allows the upperlimits for the characteristic size of the soft X-ray (SXR) source L(t) to be estimated under the assumptionthat the density n(t) is determined by the plasma frequency νp. If the SXR source with a higher density isinside the radio source, then the size of the SXR source will be L(t) (EM(t)/2n(t)2)1/3, where EM(t)is the emission measure. For three flares (C7.2 on December 22, 2009, M2.9 on July 6, 2012, and X1.1 onJuly 6, 2012) we calculate the expansion speeds of the SXR source V (t) ∼ dL(t)/dt, which are comparedwith the estimates of the sound speed and the Alfve´ n speed. By “magnetic detonation” wemean the processof the propagation of magnetic reconnectionwith a supersonic speed in eruptive flares. Magnetic detonationand the succeeding coronal mass ejection (CME) were realized in the December 22, 2009 C7.2 and July 6,2012 X1.1 flares, in which supersonic and super-Alfve´ n speeds were reached if the density of the SXRsource was lower than 2.1 × 109 and 7.4 × 108 cm−3 (νp 410 and 245 MHz), respectively. There wereno magnetic detonation and CME in the July 6, 2012 M2.9 flare, whose radio emission frequencies wereonly above 1415 MHz (n 2.5 × 1010 cm−3). For magnetic detonation in the July 6, 2012 X1.1 flare wehave estimated the magnetic field strength, the reconnection electric field strength, the plasma flow, and theCME mass.

Expansion of the Soft X-ray Source and ‘‘Magnetic Detonation’’ in Solar Flares

Expansion of the Soft X-ray Source and ‘‘Magnetic Detonation’’ in Solar Flares

Small-sized bright point-like source of picosecond soft x-ray pulses based on a high-voltage vacuum discharge

A small-sized soft x-ray (energy ≤ 1 keV) source based on a high-voltage vacuum discharge with a current of 20 kA and an ultrashort pulse duration of about 10 ps has been developed. It was shown that the radiation was emitted by a micropinch, which was formed in the discharge plasma and had a size of the order of a micrometer. In a single shot, an image of the test object was obtained with a resolution of several micrometers.

Design and Development of Cfrp Tubular Structure For Soft X-Ray Telescope Payload of Astrosat

India has launched an astronomical space based observatory ASTROSAT in the year 2015 for unravelling the some of the secrets of our universe. Soft X-ray Telescope (SXT) was one among the payloads onboard for studying the sources of Soft X-rays in deep space. A composite structure was required for this purpose. It had to support the payload elements and maintain their relative locations precisely during launch as well as during its operation, in-orbit. The interface with the spacecraft was at the middle of the SXT structure with one part is inside and remaining part is outside of the spacecraft deck. The structural design was carried out to meet all the structural design requirements such as stability, stiffness and strength with minimum mass under the constraints of spacecraft interface and envelope. This paper presents the details of the structural design, development and qualification of a CFRP tubular SXT structure, which has been functioning satisfactorily in-orbit.

High-Cadence Observations of Magnetic Field Dynamics and Photospheric Emission Sources in the Eruptive Near-the-Limb X4.9 Solar Flare on 25 February, 2014: Evidences for Two-Stage Magnetic Reconnection during the Impulsive Phase

—We present an analysis of the pre-limb eruptive X4.9 solar flare on February 25, 2014, by means of which we confirm a hypothesis of the two-stage energy release corresponding to two magnetic reconnection regimes in the flare impulsive phase. This flare is selected, firstly, because of its morphological peculiarities suggesting the presence of the two energy release stages. Secondly, the flare was very suitably located near the solar limb and it was well-observed by many instruments. We performed an analysis of multiwavelength observational data of this flare region to find a connection between changes of the photospheric magnetic field, morphology of hard and soft X-ray sources, dynamics of the photospheric optical emission sources, metric radio bursts, and kinematics of an eruptive structure. The simultaneous usage of the line-of-sight and vector Helioseismic Magnetic Imager (HMI) magnetograms allowed us to trace magnetic field changes during the flare impulsive phase with high temporal resolution. HMI filtergrams allowed to trace displacement of the photospheric emission sources, associated with the magnetic reconnection, with very high temporal resolution up to 2 s. Using all observational results, we argue that the found flare stages are characterized by the following magnetic reconnection regimes. The first stage is predominantly characterized by the three-dimensional zipping reconnection in the strong sheared magnetic field assuming the tether-cutting geometry. The second stage corresponds to the so-called “standard” model of eruptive flares with the quasi-two-dimensional reconnection below the eruptive flux-rope. All observational peculiarities of these two stages are discussed in details.

Realizing Attosecond Core-Level X-ray Spectroscopy for the Investigation of Condensed Matter Systems

Unraveling the exact nature of nonequilibrium and correlated interactions is paramount for continued progress in many areas of condensed matter science. Such insight is a prerequisite to develop an engineered approach for smart materials with targeted properties designed to address standing needs such as efficient light harvesting, energy storage, or information processing. For this goal, it is critical to unravel the dynamics of the energy conversion processes between carriers in the earliest time scales of the excitation dynamics. We discuss the implementation and benefits of attosecond soft x-ray core-level spectroscopy up to photon energies of 600 eV for measurements in solid-state systems. In particular, we examine how the pairing between coherent spectral coverage and temporal resolution provides a powerful new insight into the quantum dynamic interactions that determine the macroscopic electronic and optical response. We highlight the different building blocks of the methodology and point out the important aspects for its application from condensed matter studies to materials as thin as 25 nm. Furthermore, we discuss the technological developments in the field of tabletop attosecond soft x-ray sources with time-resolved measurements at the near and extended edge simultaneously and investigate the exciting prospective of extending such technique to the study of 2-dimensional materials.

Extension of the bright high-harmonic photon energy range via nonadiabatic critical phase matching

The concept of critical ionization fraction has been essential for high-harmonic generation, because it dictates the maximum driving laser intensity while preserving the phase matching of harmonics. In this work, we reveal a second, nonadiabatic critical ionization fraction, which substantially extends the phase-matched harmonic energy, arising because of the strong reshaping of the intense laser field in a gas plasma. We validate this understanding through a systematic comparison between experiment and theory for a wide range of laser conditions. In particular, the properties of the high-harmonic spectrum versus the laser intensity undergoes three distinctive scenarios: (i) coincidence with the single-atom cutoff, (ii) strong spectral extension, and (iii) spectral energy saturation. We present an analytical model that predicts the spectral extension and reveals the increasing importance of the nonadiabatic effects for mid-infrared lasers. These findings are important for the development of high-brightness soft x-ray sources for applications in spectroscopy and imaging.

Broadband soft X-ray source from a clustered gas target dedicated to high-resolution XCT and X-ray absorption spectroscopy.

The development of the broad-bandwidth photon sources emitting in the soft X-ray range has attracted great attention for a long time due to the possible applications in high-resolution spectroscopy, nano-metrology, and material sciences. A high photon flux accompanied by a broad, smooth spectrum is favored for the applications such as near-edge X-ray absorption fine structure (NEXAFS), extended X-ray absorption fine structure (EXAFS), or XUV/X-ray coherence tomography (XCT). So far, either large-scale facilities or technologically challenging systems providing only limited photon flux in a single shot dominate the suitable sources. Here, we present a soft, broad-band (1.5 nm - 10.7 nm) soft X-ray source. The source is based on the interaction of very intense laser pulses with a target formed by a cluster mixture. A photon yield of 2.4 × 1014 photons/pulse into 4π (full space) was achieved with a medium containing Xe clusters of moderate-size mixed with a substantial amount of extremely large ones. It is shown that such a cluster mixture enhances the photon yield in the soft X-ray range by roughly one order of magnitude. The size of the resulting source is not beneficial (≤500 µm but this deficit is compensated by a specific spectral structure of its emission fulfilling the specific needs of the spectroscopic (broad spectrum and high signal dynamics) and metrological applications (broad and smoothed spectrum enabling a sub-nanometer resolution limit for XCT).

Progress and Perspectives of Spectroscopic Studies on Carbon K-Edge Using Novel Soft X-ray Pulsed Sources

The development of novel coherent and brilliant sources, such as soft X-ray free electron laser (FEL) and high harmonic generation (HHG), enables new ultrafast analysis of the electronic and structural dynamics of a wide variety of materials. Soft X-ray FEL delivers high-brilliance beams with a short pulse duration, high spatial coherence and photon energy tunability. In comparison with FELs, HHG X-ray sources are characterized by a wide spectral bandwidth and few- to sub-femtosecond pulses. The approach will lead to the time-resolved reconstruction of molecular dynamics, shedding light on different photochemical pathways. The high peak brilliance of soft X-ray FELs facilitates investigations in a nonlinear regime, while the broader spectral bandwidth of the HHG sources may provide the simultaneous probing of multiple components. Significant technical breakthroughs in these novel sources are under way to improve brilliance, pulse duration, and to control spectral bandwidth, spot size, and energy resolution. Therefore, in the next few years, the new generation of soft X-ray sources combined with novel experimental techniques, new detectors, and computing capabilities will allow for the study of several extremely fast dynamics, such as vibronic dynamics. In the present review, we discuss recent developments in experiments, performed with soft X-ray FELs and HHG sources, operating near the carbon K-absorption edge, being a key atomic component in biosystems and soft materials. Different spectroscopy methods such as time-resolved pump-probe techniques, nonlinear spectroscopies and photoelectron spectroscopy studies have been addressed in an attempt to better understand fundamental physico-chemical processes.

A combination of soft X-ray and laser light sources offer 3D high content information on the native state of the cellular environment

Beamline B24 is a life sciences correlative cryo-imaging beamline at Diamond Light Source. B24 uses a combination of conventional and super-resolution visible-light fluorescence microscopy and soft X-ray tomography (cryoSXT) to provide 3D imaging of the cellular landscape at a resolution up to 25 nm in cryo-preserved biological samples up to 12 μm thick. B24 offers user-friendly, semi-automated 3D correlative cryo-imaging through an integrated platform of methods that encompass (a) sample preparation and evaluation, (b) data collection and processing and (c) data analysis and correlation. CryoSXT fills the current resolution gap between fluorescence and electron microscopy while cryo-structured illumination microscopy provides the additional dimension of chemical localization within the same cellular ultrastructure captured by cryoSXT. Beamline instruments can be accessed biannually by academics and industry globally through peer-reviewed standard and rapid access proposal processes. The B24 user base is primarily academic research groups studying cell function and cytopathology in biological systems ranging from viruses and algae to mammalian cells and proto-tissue complexes. Future work will consolidate development efforts and experiences gained thus far to enable high-throughput data collection. Special emphasis is placed on the delivery of other integrated advanced imaging methods such as X-ray absorption near-edge spectroscopy and phase contrast.