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Using strong electromagnetic fields generated by lasers to interact with electrons for precise diagnosis and manipulation of electron beams represents a recent focal point in accelerator technology. This approach surpasses the limitations of conventional RF technology, such as low electric field gradients and timing jitters, effectively enhancing the accuracy of ultrafast electron beam diagnostics and manipulations. As demands for precision continue to rise, the precise diagnosis of crucial parameters of ultrafast electron beams remains challenging. This study delves into the electromagnetic behavior of THz-driven devices and proposes an all-optical method utilizing single-cycle THz radiation to compress and characterize a 3 MeV electron beam. Particle tracking simulations demonstrate an astonishing compression effect, reducing the bunch length from 54.0 fs to 4.3 fs, and achieving sub-femtosecond bunch length measurement resolution. Moreover, when combined with an orthogonal THz streak camera, this method shows even greater potential in multi-bunch scenarios.

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This paper studies the dynamics of the development of laser breakdown plasma in aqueous colloids of dysprosium nanoparticles by analyzing the time patterns of plasma images obtained using a high-speed streak camera. In addition, the distribution of plasma flashes in space and their luminosity were studied, and the amplitude of acoustic signals and the rate of generation of new chemical products were studied depending on the concentration of dysprosium nanoparticles in the colloid. Laser breakdown was initiated by pulsed radiation from a nanosecond Nd:YAG laser. It is shown that the size of the plasma flash, the speed of motion of the plasma–liquid interface, and the lifetime of the plasma flash decrease with an increasing concentration of nanoparticles in the colloid. In this case, the time delay between the beginning of the laser pulse and the moment the plasma flash reaches its maximum intensity increases with increasing concentrations of nanoparticles. Varying the laser fluence in the range from 67 J/cm2 to 134 J/cm2 does not lead to noticeable changes in these parameters, due to the transition of the breakdown plasma to the critical regime. For dysprosium nanoparticles during laser breakdown of colloids, a decrease in the yield of hydrogen peroxide and an increase in the rate of formation of hydroxyl radicals per water molecule, characteristic of nanoparticles of rare earth metals, are observed, which may be due to the participation of nanoparticles and hydrogen peroxide in reactions similar to the Fenton and Haber–Weiss reactions. [ABSTRACT FROM AUTHOR]

In this paper, the characteristics of a nanosecond spark discharge with a pin–pin electrode configuration have been systematically studied. Both a streak camera with high temporal resolution and an intensified charge-coupled device (ICCD) camera are employed together to investigate the breakdown and evolution process of the discharge. The formation of initial breakdown and mode transition from streamer to spark in the electrode gap are clearly observed on the time scale of several nanoseconds with a temporal resolution of 100 ps. In addition, the time-resolved spectra technology is also used to analyze the generation and quenching mechanisms of reactive species, the electron density, and the electron temperature. The results show that there is a 1.25 ns initial discharge breakdown and that a bright cathode spot exists before the transformation from streamer to spark channel. After a faster cathode filament and a slower anode filament propagate and merge at the electrode gap, the spark discharge phase begins. The generation processes of different reactive species depend on the discharge phase to a great extent. The N2* is first generated during the streamer phase while the O*, N*, and N+ are mainly generated under the spark phase, in which the electron temperature calculated by Boltzmann plots is 2.74 eV, and the electron density determined from the Stark broadening of O lines is on the order of 1016 cm−3. [ABSTRACT FROM AUTHOR]

The ultrafast solvent dynamics of glycerol and ethylene glycol (EG) in response to a sudden charge jump in two different solute probes, coumarin 153 (C153) and trans-2-[4-(dimethylamino)styryl] benzothiazole (DMASBT), were measured by employing streak camera-based detection system (temporal resolution ~2ps). Subsequently, the detection of time-dependent solvation of the excited solute was measured by appropriately combining the streak camera data with those from the time-correlated single photon counting (TCSPC) measurements (resolution ~90 ps). Interestingly, combined data for C153 provided dynamic Stokes shift magnitudes approximately double the magnitudes accessed via the streak camera alone for these two solute probes in glycerol and EG. The initial phase of solvation in EG was found to be too fast to be measured by the present streak camera-based detection set-up and missed nearly half of the total response. The relatively shorter average excited state fluorescence lifetime of DMASBT ( ⟨ τ fl ⟩ < 0.5 ns ) prohibited the detection of the ≥ 0.5 ns solvation component reported by C153 in glycerol, highlighting the importance of ⟨ τ fl ⟩ for complete measurements of polar solvation response via dynamic Stokes shift measurements. Inappropriate choice of fluorescent probe solute with shorter ⟨ τ fl ⟩ may therefore give rise to an unexpected solute dependence of polar solvation dynamics even when detection of the rapid initial decay is ensured through ultrafast measurements. Graphical Abstract presenting schematically the measurements of the solvation response function by processing the relevant streak camera images and the time-correlated photon counting (TCSPC) data and appropriately combining them together. [ABSTRACT FROM AUTHOR]

The European Shock Tube for High-Enthalpy Research is a new state-of-the-art facility, tailored for the reproduction of spacecraft planetary entries in support of future European exploration missions, developed by an international consortium led by Instituto de Plasmas e Fusão Nuclear and funded by the European Space Agency. Deployed state-of-the-art diagnostics include vacuum-ultraviolet to ultraviolet, visible, and mid-infrared optical spectroscopy setups, and a microwave interferometry setup. This work examines the specifications and requirements for high-speed flow measurements, and discusses the design choices for the main diagnostics. The spectroscopy setup covers a spectral window between 120 and 5000 nm, and the microwave interferometer can measure electron densities up to 1.5 × 1020 electrons/m3. The main design drivers and technological choices derived from the requirements are discussed in detail herein. [ABSTRACT FROM AUTHOR]

Ionization zones, also known as spokes, are plasma instabilities manifested as locations of intensified excitation and ionization over a sputtering magnetron's racetrack. Using a linear magnetron and a streak camera, we were able to observe and quantify spoke dynamics. The technique allows us to image the onset and changes for both direct current magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS). Spokes in dcMS exhibit substructures. Spokes in HiPIMS are not stable as they shift along the racetrack; rather, they tend to grow or diminish, and they may split and merge. Their evolution can be interpreted in the context of localized electric fields and associated electron heating.

2,3,5-triphenyltetrazolium chloride (TTC) may convert into phenyl-benzo[c]tetrazolocinnolium chloride (PTC) and 1,3,5-triphenylformazan (TPF) under irradiation with light. The latter reaction, albeit enzymatically rather than photochemically, is used in so-called TTC assays indicating cellular respiration and cell growth. In this paper, we address the photochemistry of TPF with time-resolved spectroscopy on various time scales. TPF is stabilized by an intramolecular hydrogen bond and switches photochemically via an E-Z isomerization around an N=N double bond into another TPF-stereoisomer, from which further isomerizations around the C=N double bond of the phenylhydrazone group are possible. We investigate the underlying processes by time-resolved spectroscopy in dependence on excitation wavelength and solvent environment, resolving several intermediates over a temporal range spanning 15 orders of magnitude (hundreds of femtoseconds to hundreds of seconds) along the reaction path. In a quantum-chemical analysis, we identify 16 stable ground-state isomers and discuss which ones are identified in the experimental data. We derive a detailed scheme how these species are thermally and photochemically interconnected and conclude that proton transfer processes are involved.

The cylinder expansion experiment is a well‐established performance test for condensed explosives that is utilized routinely to determine pressure‐energy‐volume relationships for detonation products. The modern cylinder test employs optical interferometric techniques to measure velocity, as opposed to older realizations where streak cameras were commonplace. Despite their widespread use, questions sometimes remain as to what kind of data the velocity diagnostics in a cylinder test provide along with how to interpret such measurements and relate them to physical quantities of interest. In this study, equations are derived that fully describe the kinematics of the cylinder wall during expansion. These equations are then applied to experimental as well as synthetic data generated via a hydrodynamic simulation in order to verify the mathematical framework developed. [ABSTRACT FROM AUTHOR]

The Modulation Transfer Function (MTF) offers an objective measure to assess the imaging performance of streak cameras. This study aims to enhance the diagnostic precision of streak camera used in laser-driven inertial confinement fusion research. We introduce a novel method for evaluating the MTF of a recently developed large imaging area streak tube. This method integrates the electron optical MTF theory and the production of a reticle plate-type photocathode. Using ultraviolet and femtosecond lasers, we established two calibration platforms for the streak camera in both static and dynamic modes. We measured the radius of the electrons reaching fluorescent screen and obtained MTFs. Our findings reveal that the ultimate spatial resolutions at off-axis distances of 1.2, 4.7, 8.2, and 11.7mm are 28.5, 27.2, 26.4, 24.9 lp/mm (static) and 25.0, 22.8, 23.0, 21.2 lp/mm (dynamic). Notably, we successfully charted the ultimate spatial resolution distributions across the streak camera's full imaging area in both modes. • A novel method for calibrating the MTF of a large imaging area streak tube is reported. • The radius of the electrons reaching fluorescent screen and the static and dynamic MTFs are measured. • The ultimate spatial resolution distributions across the streak camera's full imaging area in both image modes are obtained. [ABSTRACT FROM AUTHOR]

[Display omitted] • Amyloid fibrillation of single amino acid tryptophan causes hypertryptophanemia disorder. • Tannic acid (TA) is a potent inhibitor of tryptophan fibrillation. • Microscopic images show TA-induced disruption of long tryptophan fibrils. • TA hinders the formation and stability of tryptophan fibrils. • Thermodynamic analyses provide binding constant between Tryptophan and TA. Amyloid fibrillation involving specific amino acids is a key factor contributing to the development of various neurodegenerative disorders, which remain being investigated. A promising therapeutic approach for treatment involves the use of small molecules to inhibit this amyloid fibrillation. In this study, we present experimental evidence demonstrating the efficacy of tannic acid (TA) as a potent inhibitor of fibrillation, particularly in the case of the single amino acid tryptophan (Trp), which is associated with hypertryptophanemia disorder. To investigate the kinetics of fibril formation and its suppression by TA, we have employed a combination of steady-state and time-resolved fluorescence measurements. These techniques have allowed us to monitor changes in the intrinsic fluorescence of Trp and an amyloid-specific fluorophore over time. To visualize the effects of TA on Trp fibrils, we have employed various imaging techniques such as, atomic force microscopy, transmission electron microscopy, and field emission scanning electron microscopy. These imaging techniques have vividly captured the TA-induced disruption of long Trp fibrils. Dynamic light scattering measurements have complemented these microscopic observations, further supporting the notion that TA effectively hinders the formation and stability of Trp fibrils. Additionally, we have determined the binding constant and calculated changes in the free energy associated with Trp-TA interactions through temperature-dependent spectroscopic measurements. These thermodynamic analyses provide valuable insights into the underlying mechanisms of TA-induced disaggregation of larger Trp fibrils. [ABSTRACT FROM AUTHOR]

Glow spectral kinetics of cyclotrimethylenetrinitramine (RDX) and pentaerythritol tetranitrate (PETN) based composites containing aluminum nanoparticles (average diameter 100 nm) caused by explosion stimulated by neodymium laser pulse (1064 nm, 14 ns) have been studied for the first time with nanosecond temporal resolution. The experiments have been performed in the conditions of gas-dynamic relaxation hindrance. The aluminum nanoparticles, as well as the surrounding shell of the RDX and PETN, are heated during the pulse. If the laser pulse energy density is higher than the critical one, the fluorescence, whose typical relaxation time is 50 ns, appears and spectral maximum is blue-shifted with elevating the energy density of the laser pulse. The fluorescence is related to NO 2 ● formed in the radical dissociation of RDX and PETN molecules stimulated by rapid heating in the aluminum nanoparticles explosive environment. The following exothermal decomposition reaction leads to a sample explosion in the microsecond time range. The emission spectrum of the explosion products is a thermal one with temperatures 3500 K and 3400 K for RDX-Al and PETN-Al relatively, which has been estimated using spectral pyrometry approach. [ABSTRACT FROM AUTHOR]

X‐rays and forward ion emission from laser‐generated plasma in the Target Normal Sheath Acceleration regime of different targets with 10‐μm thickness, irradiated at Prague Asterix Laser System (PALS) laboratory at about 1016 W/cm2 intensity, employing a 1,315 nm‐wavelength laser with a 300‐ps pulse duration, are investigated. The photon and ion emissions were mainly measured using Silicon Carbide (SiC) detectors in time‐of‐flight configuration and X‐ray streak camera imaging. The results show that the maximum proton acceleration value and the X‐ray emission yield growth are proportional to the atomic number of the irradiated targets. The X‐ray emission is not isotropic, with energies increasing from 1 keV for light atomic targets to about 2.5 keV for heavy atomic targets. The laser focal position significantly influences the X‐ray emission from light and heavy irradiated targets, indicating the possible induction of self‐focusing effects when the laser beam is focalized in front of the light target surface and of electron density enhancement for focalization inside the target. [ABSTRACT FROM AUTHOR]

In the current study, streak camera was used to find concentricity of the assembly during detonation, investigate and compare shock front within the high explosive and behavior of the shock front on the surface of the liner, one containing wave shaper and the other without wave shaper. Streaks revealed that the whole assembly was concentric till the formation of the jet. Observed streaks vindicate the uniform propagation of shock front in both the cases. Results obtained for shock front velocities are in agreement with those obtained from simulations. In the presence of wave shaper higher shock front velocity was observed both in simulation and experiment. Simulation without wave-shaper showed that shock front struck the copper cone at grazing angle while in the presence of wave-shaper it struck at an angle of 125°.

Time‐resolved X‐ray excited optical luminescence (TR‐XEOL) was developed successfully for the 23A X‐ray nanoprobe beamline located at the Taiwan Photon Source (TPS). The advantages of the TR‐XEOL facility include (i) a nano‐focused X‐ray beam (<60 nm) with excellent spatial resolution and (ii) a streak camera that can simultaneously record the XEOL spectrum and decay time. Three time spans, including normal (30 ps to 2 ns), hybrid (30 ps to 310 ns) and single (30 ps to 1.72 µs) bunch modes, are available at the TPS, which can fulfil different experimental conditions involving samples with various lifetimes. It is anticipated that TR‐XEOL at the TPS X‐ray nanoprobe could provide great characterization capabilities for investigating the dynamics of photonic materials. [ABSTRACT FROM AUTHOR]

The streak-camera method for measuring the laser radiation (LR) front profile with a large dynamic range and the method for measuring the power contrast based on photodiodes are described. The results of the implementation of these measurement methods at the "Luch" facility of the RFNC—VNIIEF using the SER-5 streak camera developed by the authors and specially developed optical schemes are presented. The results of measurements of the LR power contrast, performed in power experiments and demonstrating the possibility of measuring deep profiles of pulses with a dynamic range to 106 and 109 and a time resolution of 250 ps and 70 ps (at the first and second harmonics, respectively) are presented. [ABSTRACT FROM AUTHOR]

The streak camera is an ultrahigh speed detector which captures light emission phenomena occurring in extremely short time periods. In this work the operating principles of a synchroscan streak camera are introduced and an example of how the streak camera is used to measure the pulse width of ultrashort optical pulses generated from actively modelocked uncoated ridge waveguide structure InGaAsP diode lasers having an external diffraction grating cavity is shown. The pulse duration measured by an ultrafast streak camera is as short as 13 ps at 1.3 µm and 29 ps at 1.55 µm at a repetition rate of 1 GHz. [ABSTRACT FROM AUTHOR]

Abstract We report the study of the fast rise time and decay time in the ps time scale of the excitonic luminescence of a multiple quantum well (MQW) heterostructure of InGaN/GaN, including the excitation density effect. These structures were proposed as ultrafast scintillators for soft X-ray detectors and particle beam diagnostics. Measurements were carried out with a Hadland Imacon 500 streak camera following excitation of the sample by laser pulses of few tens of µJ at 266 nm and 400 nm, with pulse duration less than 200 fs. The rise time of the detected MWQ luminescence was less than 10 ps, with a possible contribution from the detection system and signal collection geometry. The calibration and the signal processing techniques employed to fully exploit the time resolution of the detection system are also described. [ABSTRACT FROM AUTHOR]

Abstract Axial radiation properties of Z-pinch dynamic hohlraum have been investigated experimentally on JULONG-I facility in China. A new method of time resolved temperature diagnostics in dynamic hohlraum experiments has been developed via a one-dimensional (1-D) imaging system consisting of a streak camera. With the help of the axial radiation power profile measured by an X-ray power measurement system using the same type of scintillator as in the 1-D imaging system, time resolved temperature distribution along the one-dimensional space in dynamic hohlraum experiments are extracted by a special mathematical transform process of the image. The peak radiation temperature in the centre is more than 100 eV. The radiation temperatures are also estimated by the 1-D Multi-IFE-Z program. [ABSTRACT FROM AUTHOR]