This work reports the development of a homemade thermoelectric measurement apparatus designed for in situ angle-resolved transport studies under cryogenic temperatures and high magnetic fields. The system employs a chip resistor as a heater to establish a stable longitudinal temperature gradient (ΔT), where ΔT denotes the temperature difference across the sample, while a Type-E thermocouple is integrated for temperature-difference monitoring. A key feature of this design is the integration of the measurement assembly onto a Physical Property Measurement System rotator probe, enabling precise stepwise modulation of the magnetic-field orientation relative to the sample's crystallographic axes under high-vacuum conditions. The apparatus achieves a low noise floor, resolving Seebeck and Nernst signals with fluctuations confined to approximately ±10 nV/K, and its accuracy and the associated sources of measurement error are characterized using a Constantan reference sample. The setup is further demonstrated through angle-dependent measurements on ZrTe5 and BiSbTeSe2 (BSTS2) single crystals, highlighting the applicability of this methodology for investigating thermoelectric transport properties of topological and functional materials.
We report the development and initial applications of the multi-functional research and development beamlines BL-11A and BL-11B at the Photon Factory, which are designed to enable simultaneous use of hard and soft x-rays. The two beamlines share a common bending-magnet source and deliver independently monochromatized hard- and soft-x-ray beams that can be focused onto the same sample position in a downstream experimental hutch, providing a versatile platform for two-beam experiments in which hard and soft x-rays can serve as pump and/or probe beams in various combinations. As proof-of-concept demonstrations, we performed probe-probe measurements of water electrolysis on a cobalt electrocatalyst and pump-probe measurements of x-ray-induced dissociation of a caged compound. In the probe-probe scheme, hard- and soft-x-ray absorption spectroscopy was carried out simultaneously to track correlated changes in the catalyst oxidation state and oxygen-related intermediates during the oxygen evolution reaction. In the pump-probe scheme, chemical changes in 2-iodosobenzoic acid induced by hard-x-ray excitation at the iodine L3 edge were monitored using soft-x-ray absorption spectroscopy at the oxygen K edge.
An α-drift tube linac (DTL) is a high-performance linac conceived for radioisotope production. The use of alpha particle beams may make yielding radionuclides hard to obtain with traditional nuclear reactors or by proton accelerators, by exploiting new reaction routes. This approach may lead to better radionuclide impurity profiles, simplifying the radiochemical separation and purification process. The key idea of the α-DTL is to use a high duty cycle linac composed of an electron cyclotron resonance ion source, a radio frequency quadrupole, and a DTL, able to accelerate an average current of 0.5 mA alpha beam from few MeV to 40 MeV, to cover the cross sections of many interesting reactions for radionuclides. The innovative feature of this linac is the capability of regulating energy at the exit of the DTL, by a particular use of the stabilization system (post couplers) of the DTL cavity.
We demonstrate a frequency-referenced vector measurement of weak residual magnetic fields using a hybrid 87Rb-129Xe magnetometer operated in a near-zero-field environment. The magnetic-field magnitude is obtained from the Larmor precession frequency of hyperpolarized 129Xe nuclear spins via free-induction decay (FID) detection, while a three-axis magnetic-field reversal technique is employed to reconstruct the full vector field and overcome the intrinsic scalar nature of FID-based magnetometry. Experiments in a magnetically shielded environment achieve sub-10 pT uncertainty, with a linear response extending from near-zero fields to several hundred nanotesla. This approach provides a robust and practical route for accurate vector magnetic-field characterization.
In this work, we present an end-station with two perpendicular high-efficiency soft x-ray spectrometers at the plane grating monochromator beamline in the Physikalisch-Technische Bundesanstalt laboratory at the electron storage ring BESSY II. It is designed for polarization-dependent x-ray emission spectroscopy and resonant inelastic x-ray scattering spectroscopy and covers the photon energy range from 80 to 1100 eV. Depending on the energy range to be monitored, either one of two spherical mirrors and either one of three variable line spacing gratings in each spectrometer is selected to provide optimal performance in terms of resolving power and detection yield. A calibration of the optical components and detection devices enables quantitative measurements and the possibility of the determination of x-ray fluorescence fundamental parameters in the soft x-ray range.
Time-of-flight mass spectrometry (TOF) is widely adopted to characterize the charged particles emitted from ionic liquid electrospray thrusters (ILETs). The Bradbury-Nielsen gate (BNG) offers advantages such as high geometric transparency and low control voltage, making it particularly suitable for bipolar beam measurements of ILETs in TOF systems. However, BNG fabrication poses significant challenges, including poor controllability of interwire spacing, non-uniform wire tension, and insufficient mechanical fixation reliability. In this work, an integrated and laboratory-accessible BNG structure and a corresponding manual fabrication method are presented. The completed BNG exhibits an average measured wire spacing of 0.505 mm (standard deviation 0.018 mm), representing a 1% deviation from the design value of 0.5 mm, and a transparency of 76%. Experimental characterization demonstrates that voltage pulse rise time remains below 63 ns with the control voltage in the range of 500-1500 V. The BNG was further evaluated in an ILET-relevant TOF setup. For gate voltages ≥800 V, the beam blocking efficiency exceeded 95% for both positive and negative beam polarities. These results demonstrate that the proposed design achieves competitive gating performance through a fabrication route accessible to common laboratories, making it a practical solution for TOF diagnostics of ILETs.
Scaling superconducting quantum processors to hundreds of qubits requires frequency-multiplexed readout architectures, where the non-uniform gain profile of Traveling-Wave Parametric Amplifiers (TWPAs) creates a critical bottleneck. We present an automated optimization framework that addresses the weakest link problem in multiplexed readout by employing a geometric mean cost function to maintain a uniform signal-to-noise ratio (SNR) profile across all channels. Through systematic characterization of a 5-qubit system, we demonstrate that readout fidelity saturates above SNR ≈ 2.5, indicating that in the high-performance regime SNR is a more effective optimization metric for TWPAs than readout fidelity. Our optimization framework, based on the Nelder-Mead simplex algorithm with continuous parameter tuning, reaches the optimized operating point in ∼100 measurements, reducing the search effort by a factor of 4.5 compared to a 451-point exhaustive grid method. Notably, the continuous optimization surpasses the grid search maximum by 12.8% in geometric mean SNR, confirming its superior efficiency over conventional grid search methods. This automated approach provides a scalable solution for maintaining a uniformly high level of readout fidelity across various amplifier devices in large-scale quantum processors.
In industrial settings, magnetic encoders suffer from structural errors and random noise, making conventional angle demodulation methods that assume ideal sine-cosine signals hard to be both accurate and robust under complex conditions. Moreover, standard filters often fail in these scenarios because their static observation models and fixed noise parameters cannot adapt to structural distortions. To address this, this paper proposes a hybrid error compensation framework that integrates a neural network with an extended Kalman filter (NN-EKF). The neural network reconstructs signals that satisfy the quadrature relationship from noisy sine-cosine sequences sampled by the ADC and predicts the uncertainty parameters required by Kalman filtering. This provides the EKF with observation inputs and noise priors that are more consistent with its physical assumptions. Meanwhile, within an uncertainty-weighted multi-task learning framework, signal reconstruction and phase estimation are optimized jointly. Simulation results under mixed error conditions show that NN-EKF reduces the mean absolute error (MAE) by about 98% compared with arctangent demodulation and achieves lower MAE, RMSE, and maximum error than EKF, phase-locked loop, Kalman-Gradient Descent, and KalmanNet. On a hardware test platform, the proposed method achieves a maximum angle error of 0.0349°. Without target-sensor fine-tuning, NN-EKF reduces the RMSE by 84.2% and 83.1% on unseen tunneling magnetoresistance and Hall sensors. Furthermore, a lightweight lookup-table scheme constructed based on the NN-EKF output satisfies the real-time deployment requirements of embedded systems with only an additional error of ∼0.0022°, validating the engineering feasibility and practical potential of the proposed hybrid framework.
As a key component of rotating machinery, rolling bearing fault characteristic signals are susceptible to multi-source coupling interference, leading to weak fault features easily submerged and difficult to extract. Aiming at the large decomposition error and low computational efficiency of Variational Mode Decomposition (VMD) in extracting fault features under single and compound bearing fault modes, as well as the limitations brought by empirical parameter selection, this paper proposes a novel bearing fault diagnosis method. The overall VMD framework is optimized by the Adaptive Spiral Flying Sparrow Search Algorithm (ASFSSA), which is further combined with the Hybrid Particle Swarm Optimization (HPSO)-improved Convolutional Neural Network (CNN). First, the ASFSSA adaptively optimizes VMD’s core parameters, including the mode quantity K and penalty factor α, which addresses the issue that traditional VMD parameters rely on empirical assignment and achieve precise decomposition of fault signals. Second, sample entropy (SampEn) is adopted only as the fitness function to quantify the complexity and stationarity of each decomposed intrinsic mode function and provide objective quantitative criteria for parameter optimization. To eliminate circular SampEn self-verification flaws in optimization and evaluation, six external quantitative metrics are added to fully evaluate fault signal decomposition performance. Finally, HPSO optimizes CNN hyperparameters, including learning rate, hidden nodes, and L2 coefficient, to boost the model’s fault classification accuracy. Simulations and experiments prove that the method outperforms traditional algorithms for accurate, reliable bearing fault diagnosis.
Nuclear resonant scattering (NRS) provides the basis for powerful synchrotron-based techniques, including synchrotron Mössbauer spectroscopy (SMS) and nuclear resonant inelastic x-ray scattering (NRIXS), which probe the elastic, magnetic, thermodynamic, and vibrational properties of iron-bearing materials and are, therefore, well suited for studying the structure and composition of Earth's and planetary interiors. Here, we report the development and commissioning of a double-sided laser heating system for diamond anvil cell experiments at the 3-ID beamline of the Advanced Photon Source (APS). A key feature of the system is a 7° offset between the x-ray and laser-delivery paths, which positions the near-sample mirrors outside the x-ray path. This design minimizes x-ray absorption, enhances the NRS signal rate during laser heating, improves imaging quality, and significantly reduces thermal drift during extended data acquisition periods. The setup is optimized to match the reduced x-ray beam size available after the APS upgrade, making NRS measurements under extreme pressure-temperature conditions more practical. In addition, the system supports complementary online ruby fluorescence and x-ray diffraction measurements for characterizing samples before and after laser heating. We demonstrate the performance of the system through representative SMS and NRIXS measurements conducted under simultaneous high-pressure and high-temperature conditions.
This study investigates the characteristics of X-pinch plasmas driven under low current rise rate (dI/dt) conditions using soft x-ray spectroscopy combined with the Bennett relation. X-pinch experiments were conducted on the SNU X-pinch device using copper wires at a low dI/dt of 0.2-0.3 kA/ns. The resulting 1-10 keV soft x-ray signals, measured by using an x-ray-filtered AXUV photodiode array, exhibit significant nonlinear effects due to the high intensity of the soft x-ray pulses. This work characterizes the nonlinear behavior of the AXUV-HS5 Si PIN photodiodes under intense pulsed radiation using a pulsed laser. We identified a charge conservation property that the total collected charge remains proportional to the incident pulse energy despite temporal profile distortion. Based on this diagnostic finding, we developed and applied a new framework for plasma parameter estimation. By combining a spherical emission model with the Bennett equilibrium, this approach determines that the soft x-ray source plasma is a "bright spot," characterized by a plasma density ne ∼1021 cm-3, size d ∼30-40 μm, at electron temperature Te ∼1 keV, and an emission duration tB ∼1 ns, rather than an extremely compressed "hot spot."
We discuss a modified polarization-dependent transmission method to measure birefringence in a nematic liquid crystal (NLC) cell of moderate thickness. Determining birefringence accurately by monitoring the transmitted intensity in a thick NLC cell (and hence a large path difference) is challenging for the following two reasons: (a) a large drop in transmitted light intensity due to scattering losses near the clearing temperature and (b) a sharp jump in the birefringence over a narrow temperature window close to the clearing point. To detect the transmitted light intensity profile precisely, we converted the incident laser into a modulated signal using an optical chopper and measured the transmitted light intensity using a sensitive photodetector coupled to a lock-in amplifier (LIA). Furthermore, the transmitted intensity was normalized against a reference beam to account for any fluctuations in the laser source. The birefringence and the critical exponents (β and α) calculated using this method agree with reported data within experimental error.
A polarization rotator is designed and fabricated to rotate the polarization direction of an electromagnetic wave to an arbitrary angle. The device employs a mirror-symmetric, paired periscopic architecture composed entirely of reflective elements, which enables operation over a broad wavelength range. Linearly polarized lasers spanning the visible, near-infrared, and mid-infrared regions are used to validate its broadband compatibility and high orientational accuracy. Extinction-ratio measurements confirm effective preservation of polarization, meeting the requirements of most optical applications.
We present the design and calibration of a cryogenic adapter for a diamond anvil cell (DAC) that enables optical spectroscopy under simultaneous low temperature and high pressure conditions. What differentiates our design from prior efforts is the straightforward construction and opportunity for rapid implementation using common cryogenic hardware. The motivation for this development work arose from room temperature photoluminescence measurements of CrSBr, a chalco-halide that exhibits strong quenching of the emission intensity on approach to the pressure-induced transition near 7.6 GPa. Normalized spectra reveal reversible red and blue shifts of the broad emission band with compression and decompression, consistent with pressure-tuned changes in the inter-layer interactions. To host such measurements, the cryo-DAC adapter provides thermally stable cryogenic operation (with either liquid nitrogen or helium) while maintaining optical access and precise pressure calibration. These measurements demonstrate that compression suppresses exciton-phonon coupling in CrSBr. Construction details, required instrumentation, pressure calibration using ruby fluorescence and temperature control are described. Typical cryogen consumption is 4-5 liters per run.
High-energy x-ray sources are widely used across many fields and industries. Understanding and characterizing these sources is critical for these potential applications and uses. The filter stack spectrometer (FSS) is a compact and portable diagnostic that employs a stack of alternating image plate detectors and filters, and when paired with the unfolding routine based on randomized perturbative minimization methods, it can characterize these sources with high accuracy. However, limitations such as large measurement uncertainties and flattened attenuation curves in the MeV photon range make the spectral inversion difficult and less accurate. In this paper, we present a novel filter stack design that enhances the sensitivity of the FSS by leveraging Compton electrons generated in high-Z filters. This approach produces a more distinct diagnostic signal, making the spectrometer better suited for higher photon energies and more resilient to experimental uncertainties. We also demonstrate the design process for the filter stack through our modular Monte Carlo N-particle approach, allowing us to calculate response matrices rapidly.
To address suspension instability and rotor drop caused by displacement sensor faults in the Magnetic-Liquid Double Suspension Bearing (MLDSB), this paper studies anti-drop control under sensor fault conditions. A two-degree-of-freedom dynamic model of the radial support unit is established to describe the coupling among electromagnetic suspension force, hydrostatic supporting force, and rotor displacement. Differential displacement sensor fault models are then developed for open-circuit faults, fixed-bias faults, impact faults, and periodic interference faults. For abrupt measurement abnormalities, a self-sensing displacement reconstruction method based on the force-balance principle is proposed to replace faulty feedback through fault detection and signal switching. To suppress the residual oscillation that remains under periodic interference faults, a composite fault-tolerant control strategy combining adaptive back-propagation neural network proportional-integral-derivative (PID) and incremental PI is further introduced. Simulation results show that conventional constant-ratio control is highly sensitive to sensor feedback and cannot maintain stable suspension under the four fault conditions. Self-sensing constant-ratio control effectively suppresses instability caused by open-circuit faults, fixed-bias faults, and impact faults and achieves stable post-fault suspension. Under periodic interference faults, the proposed composite control strategy further reduces sustained oscillation, drives the rotor back to the reference position within a short time, and restores the control voltage, current, and supporting force to normal levels. The results show that the proposed hierarchical composite fault-tolerant control framework improves the anti-drop capability and operational reliability of the MLDSB under displacement sensor faults.
The Compact Laser Plasma Accelerator II at Peking University provides high-gradient proton acceleration with potential applications in medical treatment. However, the laser-generated beam exhibits shot-to-shot fluctuation and the beamline transport system is highly complex, making beam simulation and tuning challenging. The results from beam simulation software may deviate from experimental observations and the long simulation time limits their applicability in online diagnostics and beam tuning. In this work, we propose a recurrent neural network encoder-decoder surrogate model for accelerator beam prediction. This model aligns well with the sequential characteristics of magnet components and beam diagnostic outputs in accelerator systems. Our results show that the proposed model outperforms a multilayer perceptron baseline, and we further leverage it to enable fast genetic algorithm optimization and backpropagation-based optimization of detector outputs.
To address the large partial discharge (PD) positioning errors caused by the inadequate modeling accuracy of traditional models for the complex internal structures of transformers, as well as the difficulty in solving strongly nonlinear positioning equations, this paper proposes a PD positioning method based on time delay compensation and an Improved Artificial Lemming Algorithm (IALA). First, the proportional correlation between the electromagnetic wave propagation delay and internal geometric features is revealed, and a correction model for the propagation delay is established to modify the positioning equations. Subsequently, Sobol sequence initialization and a dynamic multi-leader collaboration mechanism are introduced to overcome the defects of traditional algorithms, such as premature population convergence and blind search behavior. This enables an efficient solution to the aforementioned strongly nonlinear positioning equations. Furthermore, a complete positioning strategy of "IALA initial positioning-time delay determination and compensation-secondary precise positioning" is proposed. Finally, multi-point positioning experiments conducted on a physical transformer demonstrate that the proposed method effectively eliminates the severe multipath interference caused by the core and windings. Compared with traditional algorithms, the positioning error is reduced by ∼53%, significantly improving the spatial positioning accuracy of PD sources in transformers.
Single particle light scattering has gained popularity due to its methodological simplicity, short measurement times, high precision, and suitability for high-throughput particle analysis. This work quantitatively validates two flow cytometry prototypes with regard to particle size and concentration determination based on qualitative studies conducted previously. First, the influence of the interrogation volume on the distribution of the measured scattering signal was examined. The broadening of the scattering signals was found to depend on the diameter of the sample stream, with smaller diameters leading to less broadening. To detect particle sizes ranging from 100 to 1000 nm, an intensity range of at least five orders of magnitude must be detectable. The new device uses two linear amplifiers to enable coverage of six orders of magnitude. Validation of particle size measurements was performed using certified reference standards, resulting in a bias of 8.4 nm and a relative standard deviation of 0.27%. A working range of 30 to 1600 nm, depending on the material, was established. The analysis of a multimodal size distribution was demonstrated. Finally, particle concentrations in the range of 105 to 108 particles per ml could be accurately determined. The amount of fine and coarse fractions in multimodal systems could also be reliably identified. Thus, not only did the validation show excellent results but also offers opportunities for future research on highly complex multimodal systems with widely distributed properties, which has been made possible due to these new technical developments.
