Review of Scientific Instruments最新文献

The development of systems to measure and optimize emerging energetic material performance is critical for Chemical Warfare Agent (CWA) defeat. In order to assess composite metal powder efficacy on CWA simulant defeat, this study documents a combination of two spectroscopic systems designed to monitor the decomposition of a CWA simulant and temperature rises due to combusting metal powders simultaneously. The first system is a custom benchtop Polygonal Rotating Mirror Infrared Spectrometer (PRiMIRS) incorporating a fully customizable sample cell to observe the decomposition of Diisopropyl Methyl Phosphonate (DIMP) as it interacts with combusting composite metal particles. The second is a tunable diode laser absorption spectroscopy (TDLAS) used to monitor increases in background gas temperatures as the composite metal powders combust. The PRiMIRS system demonstrates a very high signal to noise ratio (SNR) at slow timescales (Hz), reasonable SNR when operating at faster timescales (100 Hz), and capabilities of resolving spectral features with a FWHM resolution of 15 cm-1. TDLAS was able to monitor temperature rises between room temperature and 230 ± 5 °C while operating at 100 Hz. For testing, liquid DIMP was inserted in a preheated stainless steel (SS) cell to generate DIMP vapor and (Al-8Mg):Zr metal powders were ignited in a SS mount with a resistively heated nichrome wire at one end of the cell. The ignited particles propagated across the cell containing DIMP vapor. The path averaged gas temperature in the preheated SS cell rises rapidly (100 ms) and decays slowly (<5 s) but remains below 230 °C during particle combustion, a temperature at which the thermal decomposition of DIMP is not observed over similarly short timescales (seconds). However, when combusting particles were introduced to the DIMP vapor (heterogeneous environment), spectral signatures indicative of decomposition product formation, such as isopropyl-methyl phosphonate (IMP) and isopropyl alcohol, were observed within seconds.

This article covers the in-vessel design of the SPARC interferometry diagnostic system, highlighting unique aspects of the systems design and port plug integration in preparation for "day-1" plasma operations as a critical diagnostic for density feedback control. An early decision for the diagnostic was to deploy two lasers in the infrared wavelength spectrum, allowing the system to have a higher optical throughput. The optimization of the in-vessel geometry for the diagnostic follows a similar approach, focusing on de-risking possible damage to the plasma facing optical components by moving them further from the plasma with an orientation that provides a greater possibility for protective features to be added. The inclusion of in-vessel optical assemblies requires detailed design efforts of custom all-metal parts, designed to remain functional when subjected to harsh operational conditions, in many cases for the entire SPARC lifetime. The details presented here were included in the design to ensure that the assemblies can not only withstand a major electromagnetic disruption or thermal event but also maintain good stability through normal operations. The design also addresses more nuanced effects, such as the transient heat loading of the plasma facing mirrors. Through the utilization of modeling and design tools, these effects were brought into the design and simulation workflow, further reducing uncertainty as the system moves toward system commissioning.

This work proposes a new rotary piezoelectric energy harvester using magnetic excitation inspired by the fan blade. The configuration and operating principle of the harvester are introduced. Then, the equivalent nonlinear model of the piezoelectric beam is established based on the Euler-Bernoulli theory and the Rayleigh-Ritz method. Finite element simulation is used to obtain the vibration performance of the piezoelectric beam, and the first order natural frequency is obtained as 22.059 Hz. A prototype of the proposed harvester is developed, and a series of experiments are carried out. The effect of magnet deflection angle, magnet mass, and the number of magnets on the output performance of the harvester is studied in detail by experiments. The experimental results proved that the harvester obtained a relatively better output performance when the deflection angle of the drive magnet is 30°. In addition, the harvester generated the maximum output voltage when the rotary speed is 165 rpm, which is consistent with the simulation result. The harvester achieved an average power of 43.5 mW when the resistance was 130 kΩ under the rotary speed of 165 rpm. The output power can satisfy the power consumption of low-power electronic devices, such as LEDs, calculators, and electronic meters.

In the post-anesthesia care unit, there is a high occurrence of residual neuromuscular blockade, which puts patients at risk of negative consequences such as hypoxia. Assessment based on the train-of-four ratio (TOFR) has been used to avoid residual neuromuscular blockade when the TOFR is greater than 0.9, measured at the adductor pollicis muscle (APM). The most commonly used quantitative neuromuscular monitoring (QNM) modalities include acceleromyography (AMG) and electromyography (EMG). However, the poor user-friendliness of current QNM methods hinders their widespread adoption. To overcome this, we developed a new monitoring method using ultra-fast ultrasound imaging to generate a two-dimensional map of muscle transient motion, i.e., sonomechanomyography (SMMG). SMMG of the APM and AMG of the thumb were used to get the TOFR of 20 normal adults. The results showed no significant difference between the left and right hands for both AMG and SMMG TOFR, with p-values larger than 0.05. In addition, the mean accuracy of SMMG TOFR (0.6% relative error) was higher than AMG (1.4% relative error). Moreover, the Bland-Altman plot showed that all the difference values were within the limits of agreement and the mean bias was 0.02, indicating that the two methods had a very good agreement. In particular, using SMMG did not require additional calibration before testing. Overall, the results demonstrated that the method has the potential as a new QNM approach for further clinical studies to benefit patients in need. To demonstrate its clinical potential, further studies are required to evaluate this method in patients during and post-anesthesia.

Large volume presses are used to simulate extreme environments within the Earth, enabling the investigation of the physical properties of subsurface materials. However, existing pressure calibration methods do not facilitate in situ observation of continuously varying chamber pressures. The Mn-Cu alloy, known for its piezoresistive properties, has not been extensively studied under ultra-high temperatures. This study investigates the piezoresistive effect of a Mn-Cu alloy wire across a temperature range of room temperature to 1000 °C and pressures up to 4.5 GPa. The results demonstrate that the Mn-Cu alloy wire can be a reliable manometer for in situ pressure monitoring in large volume presses, providing accurate absolute pressure measurements.

The spectrum of neutrons emitted by thermonuclear plasmas encodes information about the fuel ion distribution function. Measuring these fast neutron spectra with sufficient resolution allows for the measurement of plasma properties such as the ion temperature and strength and energy of fast ion populations. Liquid organic scintillators are a commonly used fast neutron detection technology because of their high detection efficiency and ability to discriminate between neutrons and gammas. However, performing detailed spectroscopy with these detectors is difficult because of the isotropic nature of neutron scattering on protons, the dominant mechanism of interaction. Deuterium-based scintillators have shown promise as a superior spectrometer technology because of the anisotropic nature of neutron scattering on deuterium, which significantly improves the condition number of the detector response matrix [Lawrence et al., Nucl. Instrum. Methods Phys. Res., Sect. A 729, 924 (2013)]. Deuterated-xylene, now available commercially, has advantages in light output and safety over benzene-based deuterated scintillators [Becchetti et al., Nucl. Instrum. Methods Phys. Res., Sect. A 820, 112 (2016)]. We present experimental spectrum unfoldings made by 2 in. right cylindrical protiated-xylene and deuterated-xylene detectors with response matrices generated with Geant4 and additional data from the literature. We compare their performance by measuring the neutron spectrum produced by an AmBe source and deuterium-tritium (DT) neutron generators. We find that the deuterated scintillator outperforms the protiated one for AmBe and DT spectra, suggesting deuterated-xylene should be considered for future fusion neutron spectrometry applications.

Understanding the erosion of plasma facing components in fusion devices is vital, particularly for long-pulse operations. This study presents the application of synthetic optical diagnosis on the all-W WEST tokamak. The analysis reveals reflections as significant contributors to measured emission, varying across main chamber limiters and divertor targets. Reflections at divertor locations can be up to 50% of measured emission while 95% at limiter locations. Oxygen is investigated as a proxy for low-Z species and underscores the importance of reflections in interpreting optical diagnostics, especially for validating plasma-material interactions and scrape-off layer impurity transport codes. As more fusion devices adopt full metal walls, the accurate assessment of reflections will become increasingly crucial for erosion analysis and plasma control.

Soft x-ray (SX) tomography is a useful diagnostic in fusion research, and a multi-channel SX diagnostic will be installed in JT-60SA, the largest elongated tokamak in the world. However, in the SX diagnostic of JT-60SA, plasmas will be only viewed from the low field side and the upper side of plasmas; the sight lines are limited, which would be common in future devices as well as JT-60SA. This kind of limited sight lines is not preferred for SX tomography to investigate the spatial structure of magnetohydrodynamics (MHD) modes because inadequate information of plasmas makes artifacts in the reconstructed SX profiles. One of the solutions to reduce the artifacts is to employ L1 regularization, which gives the essential and sparse contributions [Kaptanoglu et al., Phys. Plasmas 30, 033906 (2023)]. In this study, as a first topic, the applicability of L1 regularization to reduce the artifacts in SX tomography with limited sight lines is investigated with traditional L2 regularization for a high beta scenario of JT-60SA where MHD modes would occur. Here, as a series of basis functions, the Fourier-Bessel series (FBS) is employed because FBS has the poloidal Fourier modes explicitly. A disadvantage of FBS is that the accurate equilibrium inside the last closed flux surface (LCFS) is needed; interior measurement such as the motional Stark effect measurement is required, which is not always available during a whole discharge. The second topic of this study is to investigate other appropriate basis functions to study the spatial structure of MHD modes in elongated tokamak plasmas. Here, we introduce Saito's Laplacian eigenfunction (LEF). Saito's LEF can be calculated if LCFS is given and the LEF is expected to show the explicit poloidal Fourier mode. Because the calculation of LCFS with magnetic measurements is a basic task of plasma operations, Saito's LEF may be used anytime. Our investigation showed that L1 regularization can strongly improve the SX tomography with the traditional L2 regularization having FBS/LEF and would be effective against other tomographic problems in fusion devices.

In inertial confinement fusion, hydrogen isotopes are fused together under high pressures and temperatures. Typically, the duration of these experiments is incredibly short, on the order of around 60-150 ps. Due to the high radiation environment, a detector's signal is typically data linked far distances to a protected location. The diagnostic challenge for fusion reaction history measurements is to measure signals of interest maximizing dynamic range while also maintaining time resolution on the order of 10 ps. In this work, we present a new experimental optical data link used to efficiently transport diagnostic signals over great distances to the recording system while not restricting the dynamic range. The concept of a three phase Mach-Zehnder modulator system is introduced as well as a description of the physical prototype. The initial results from testing at the OMEGA facility show that this system is a viable method for signal transportation.

A new gas analytical technique for infrared laser spectroscopy combined with differential pressure measurement (IR-DP) is developed. The basic idea of this technique is that the absorption process of molecules by laser irradiation is monitored as the pressure enhancement in a gas cell by use of a differential pressure gauge. The system is composed of a tunable IR laser system, sample cell, differential pressure gauge, and data accumulation system. Using this system, the measurements of the IR absorption spectra for cyclohexane (50 ppm) and ammonia (100 ppm) are demonstrated. By comparison of the current IR-DP spectra with conventional Fourier-transform infrared spectra, the spectral resolution is found to be about 3 cm-1, reflecting the laser resolution. Furthermore, the estimated pressure enhancement based on a simple model is consistent with the experimental results. These results suggest that the newly developed IR-DP technique is one of a powerful tool for trace gas detection.