Review of Scientific Instruments最新文献

Thermal deformation of x-ray optical elements, especially the first element exposed to high thermal loads, can significantly degrade the performance of synchrotron radiation beamlines. Accurate wavefront measurement is essential for estimating such deformations and improving optical design. Talbot interferometry, employing phase and absorption gratings to produce moiré fringes, enables wide-field wavefront sensing across areas of several to tens of millimeters. However, mismatches in the designed period ratio between the gratings introduce systematic errors in wavefront curvature estimation and surface profile reconstruction. This study investigates the impact of such period mismatches on wavefront accuracy and presents a practical calibration method. Experiments with both minimally used and long-term exposed gratings show that calibration markedly improves the precision of surface profile measurements, reducing variation by up to 50%. These results emphasize the importance of precise grating period calibration for reliable wavefront and surface figure evaluation, particularly for optics subject to thermal deformation under high-power x-ray irradiation.

Coherence Imaging Spectroscopy (CIS) is a camera-based polarization interferometry technique that provides high-spatial-resolution 2D measurements of spectroscopic quantities. Its most common application is in the field of fusion plasma diagnostics. Like other systems based on birefringent crystals, the CIS diagnostic has a characteristic delay dispersion or group delay, i.e., how much the interferometer phase response varies with small changes in wavelength. This dispersion is one of the key system parameters that must be precisely characterized in order to derive physics-relevant quantities (such as ion flow velocity and temperature) from the raw diagnostic signal. This paper reports on the validation of delay dispersion estimation methods, based on extrapolations and interpolations, for wavelength ranges hard to access with conventional calibration sources, such as spectral lamps, diode lasers, or monochromators. The methods under investigation use either the simulation of the system response adopting simple models or power-law fits of the available delay dispersion measurements. The tests are performed using two continuous-wave tunable lasers that, together, cover the range 450-750 nm without any gaps. Moreover, the analysis is repeated for three different CIS systems featuring different crystals, imaging lenses, and cameras, revealing that the crystal alignment and lens quality can substantially influence the precision of the estimation. The smallest deviation (<2%) between the estimated and measured delay dispersion is obtained with the simplest CIS setup, less prone to hardware imperfections. The systems featuring a more complex setup show deviations that can reach 20%, including spatial structures difficult to capture with the tested estimation methods.

A new L-shaped molecular beam Fourier transform microwave spectrometer (L-FTMW) has been developed at Tennessee Tech University to perform both cavity and chirped-pulse rotational spectroscopy within a single platform. The instrument features an L-shaped high-vacuum chamber comprised of stainless-steel and polycarbonate sections, allowing orthogonal operation of Fabry-Perot cavity and chirped-pulse configurations without mechanical reconfiguration. This paper focuses on the design, operation, and performance of the 8-18 GHz Fabry-Perot cavity subsystem within the L-FTMW spectrometer. The cavity is formed by two 7.5-inch-diameter aluminum mirrors with 30 cm radii of curvature, arranged near-confocally and coupled to a near-coaxial pulsed molecular beam. A custom Python-based interface enables automated high-resolution mapping of cavity resonances and broadband data acquisition with minimal user intervention. The system routinely achieves 2 kHz frequency resolution, enabling precise measurement of hyperfine spectral features. Performance was validated through measurements of benchmark systems, including OCS isotopologues and their weakly bound van der Waals complexes. The 17O13CS isotopologue (natural abundance = 0.000 397 2%, corresponding to ∼40 ppb in a 1% OCS/argon mixture) was detected within 5 min of signal averaging at natural abundance with argon as the carrier gas. The simple mechanical design and open-source control software make the L-FTMW spectrometer a versatile and accessible platform for high-resolution rotational spectroscopy and future investigations of reaction dynamics and kinetics.

Semiconductor materials characterized by wide-bandgaps are well-suitable for measuring and detecting high-energy particles, such as x rays. According to the insulating properties of metal oxides and the sensing capabilities of two-dimensional nanomaterials, magnesium oxide (MgO) becomes a promising sensing material. To change the sensing behavior of composites, metal nanoparticles used to capitalize on their synergistic effects and change in reactions. According to this, magnesium oxide/gold (MgO/Au) nanocomposite was synthesized using facile and straightforward methods, namely laser ablation in liquid and magnetic stirring. In the study of electric response to x ray, it was observed that, compared to the energy change in photons, the MgO/Au nanocomposite shows higher sensitivity to intensity changes in x radiation. In contrast, MgO nanosheets demonstrate sensitivity to energy and intensity changes in radiation. With precise ammeter and appropriate analysis, these materials, when placed in the same device, have the potential to measure the energy and intensity of x rays. It is well established that semiconductors such as MgO with wide-energy-bandgaps exceeding 5 eV can demonstrate resistances in the megaohm range in prepared samples for analysis. Due to this elevated resistance, the electric current flowing through the biased material typically falls within the hundreds of picoamperes (pA). Such low current levels pose significant challenges for measurement using standard and even advanced ammeters, as they are highly susceptible to interference from noise sources. To mitigate this challenge, we have developed and evaluated a circuit designed to supply the necessary bias voltage and accurately measure extremely low electrical currents, specifically at the 10 pA level.

Adjustable magnetic field sources have become indispensable in advanced material characterization techniques. Among these, permanent magnet assemblies offer significant advantages by reducing power consumption and minimizing Joule heating. In this work, we report on the development and integration of a tunable magnetic sample environment at the SoftiMAX beamline of the MAX IV synchrotron, employing a "magnetic mangles" configuration of four diametrically magnetized cylindrical NdFeB permanent magnets. This arrangement provides precise control of the field strength and orientation, achieving magnitudes up to 415 mT. Both in-plane and out-of-plane magnetic field configurations were explored, including a 30° tilted orientation. Our results indicate that the highest field uniformity occurs at maximum field strengths, decreasing as the field strength approaches zero. Moreover, field sweeping configurations were explored for various field orientation angles, and the hysteretic behavior as well as the field uniformity were analyzed. The system's performance was demonstrated through x-ray microscopy experiments conducted on Co nanochains and a CoGd thin film, revealing details of magnetic domain structures and magnetization reversal processes.

Calibration of instruments measuring the Earth's energy imbalance EEI as the difference of the total solar irradiance TSI and the total outgoing radiation of the Earth TOR requires precise, traceable TSI and TOR radiation standards with three congruent properties: spectral composition, power, and angular divergence. As there are no TSI and TOR standards available, EEI data should be considered estimates. To enable more accurate estimates, the proposed novel spectrometers are used. The innovative process behind it is called quasi-calibration and also compensates for the aging of the instruments. The data can be transferred to other instruments in space. SORACES allows the observation of spectral solar irradiance SSI and spectral outgoing radiation of the Earth SOR, which differ by about five orders of magnitude, with high statistical significance by the same detectors. It is equipped with a set of 16 compact Rowland spectrometers with 80 photomultiplier tubes (PMTs) and 32 radiation attenuators with transmissions from 10-1 to 10-5. The use of attenuators allows for a dynamic range of up to 12 orders of magnitude to be covered. The cadence of the spectra is one second. Based on the stability of the TSI data, quasi-calibrated measurement periods across a solar cycle are to be achieved. SORACES is intended to contribute time-stable estimated SOR data to climate research. By evaluating the spectral features of the data, annual changes in the global cover of the Earth's green biomass due to global warming are to be derived.

Accurate thickness measurement of aluminum sheets is critical for industries such as aerospace and automotive but is challenged by traditional methods' dependency on known alloy compositions. This study proposes a novel x-ray-based system to determine thickness across four aluminum alloys (1050, 3105, 5052, and 6061) with thicknesses ranging from 1 to 45 mm, independent of composition. Using Monte Carlo N-particle simulations, an optimized multi-layer perceptron (MLP) neural network, and ant colony optimization (ACO) for feature selection, the approach achieves precise predictions with reduced computational complexity. The model demonstrated high accuracy, with a mean relative error (MRE) of 1.06% on test data, outperforming conventional methods. This scalable, calibration-free system offers a robust solution for real-time thickness measurement in diverse industrial applications.

Thin polymer films are widely used as functional and protective coatings. However, determining the composition and processing conditions that produce a desired function is a tedious process due to the large number of factors that must be considered and the manual nature of most synthesis and characterization methods. Self-driving labs (SDLs), or robotic systems that prepare and test material samples, are designed to overcome this bottleneck by enabling the efficient exploration of complex parameter spaces. In this paper, we report the development and testing of the polymer analysis and discovery array (PANDA)-film, a modular SDL for electrochemically synthesizing polymer films and then determining their water contact angle as a measure of surface energy. The system is designed to be highly modular and based upon a low-cost gantry platform to facilitate adoption. In addition to validating fluid handling and electrochemical tasks, we introduce two novel modular capabilities that enable PANDA-film to run sustained campaigns to study the wetting properties of films: (1) an electromagnetic capping/decapping system to mitigate fluid evaporation and (2) a top-down optical method to determine water contact angle based upon reflectance. These capabilities are validated by depositing and characterizing a poly(allyl methacrylate) film using electrodeposition of polymer networks. Comprehensive details for replicating the hardware and software of PANDA-film are included.

This paper presents a systematical transmission coil design method for a dual-load wireless power transfer (WPT) system based on a rectangular coil structure. The main design steps are as follows: (1) The system circuit model and the mathematical dimension model of the coupling coils are established to determine the inductance range of the receiving coil and the transmitting coil. (2) Three coil inductance calculation methods such as the finite element method (FEM), greenhouse formula method and backpropagation neural network (BPNN) are analyzed and compared. The FEM and BPNN hybrid method are finally selected for determining the relationship between rectangular coil size, coil turns, and inductance, which is a more efficient modeling scheme and can achieve enough modeling accuracy. (3) Based on calculated inductance characteristics, the length and width of the rectangular coil can be obtained with a geometric mapping scheme, and moreover, the coil size with optimal costs can be estimated. Detailed theoretical analyses are provided. Finally, simulations and experiments are performed for verification.

Reducing sample volumes for electron paramagnetic resonance (EPR) spectroscopy applications places increasing demands on hardware design to preserve or enhance EPR signal intensity. This work presents the design, fabrication, and testing of dielectric resonators and multi-channel aqueous sample cells for applications in X-band (nominally 9.5 GHz) EPR. Our aim was to maximize the EPR signal intensity for sample sizes of 3-4 μl and 200 nl. These advances are summarized as follows: single-crystal sapphire and rutile dielectric resonators with very low loss tangent and high resonator efficiency; minimum dielectric resonator coupling to radiation shield to reduce ohmic losses; 3D-printed aqueous sample cells with thin multi-channel construction to minimize radio frequency dissipation in the sample; and a Gordon coupler for maximum coupling range and minimum stored energy to eliminate frequency shifts during tuning. Sample tube cross sections were designed by leveraging insights gained from analytic theory to inform finite-element modeling of electromagnetic fields. Experimental comparisons of multi-channel sample cells using a sapphire resonator exhibited a 2.2-fold increase in EPR signal intensity compared with a standard capillary at 3-4 μl, while simulations predict an additional 23% improvement with further 3D printing advances. For samples at 200 nl, a rutile dielectric resonator with a multi-channel sample cell was simulated to improve EPR sensitivity by a 2.7-fold increase compared with a capillary at the same volume.