In magnetic resonance (MR) systems, radio frequency (RF) resonators are key components in both the study transmission and receiving phases. The design of home-made, organ-specific RF resonators can be a constraint in many research projects. Such RF resonators can be built by using conductors with different cross-sectional shapes (circular wire and flat strip, hereafter named "wire" and "strip," respectively), which strongly affects the conductor resistance and then the RF resonator performance in terms of quality factor and signal-to-noise ratio, especially for low frequency MR experiments. However, both conductor types are used in different MR applications. For the design of RF resonators, it is necessary to evaluate the conductor inductance in order to define the capacitor's value for tuning the RF resonator at the desired Larmor frequency. To avoid time-consuming trial-and-error approaches and achieve a fast RF resonator-prototyping process, it is necessary to perform a priori RF resonator inductance estimation. This paper proposes the application of a numerical full-wave method based on the finite-difference time-domain algorithm to help the RF resonator builder in the choice of the conductor cross section for maintaining the same RF resonator inductance value. Simulation results accuracy was validated with workbench tests performed on some RF resonator prototypes.

In nuclear magnetic resonance (NMR) spectroscopy, the signal from nuclear spins is extremely weak, and thus, it has been desired to improve the signal-to-noise ratio (SNR). In this study, we designed a compact low-noise probe and peripheral detection system optimized for low-temperature solid-state NMR spectroscopy. We confirmed the operation of a Tx/Rx switch composed of radio frequency microelectromechanical system (RF MEMS) switches and a preamplifier using high electron mobility transistors (HEMTs), which can operate even at 20 K and under a high magnetic field of ∼10 T. In our compactly designed NMR system, we succeeded in sufficiently reducing both thermal noise and external noise. As a result, the 195Pt- and 27Al-NMR measurements for Pt and Al solid powder samples were performed at 12 T and down to 20 K, showing that the SNR was improved by 40%–50% compared with the conventional system. These experiments also provide information on the low temperature properties and operational characteristics of integrated RF electronic devices, such as the RF MEMS switch, the HEMT, and their combined circuit system.

The nitrogen-vacancy center in diamond serves as a nanoscale multi-sensor for precise magnetic and electric field measurements in optically detected magnetic resonance (ODMR) experiments. The ODMR system at cryogenic temperatures can be employed for the exploration of significant physical phenomena, such as two-dimensional ferromagnetism and current transport dynamics. Conventional systems, however, suffer from limited scanning range, low load capacity, and instability due to their reliance on cryogenic scanning mechanisms to manipulate samples, objective, and magnetic components. Here, we present a cryogenic ODMR platform utilizing all room-temperature scanning systems, enabling stable operation from 300 to 10.6 K. Our design achieves a positioner motion range of >5 cm and makes it possible to range from 50 to 5000 G, addressing critical challenges in applications requiring large-scale magnetic field scanning and broad temperature range experiments, such as quantum relaxometry studies. The system exhibits high robustness (vibrations <50 nm), high load capacity, cost-effectiveness, and ease of maintenance. Furthermore, our approach can also be directly applied to other promising quantum bit platforms, such as solid-state spin defects in silicon carbide (SiC) and so on.

Micro-Hemispherical Resonator Gyroscopes (MHRGs) serve as essential components in inertial navigation systems. This research introduces a novel digital closed-loop control system for the application of the force-to-rebalance mode. The proposed methodology utilizes a self-excitation technique to initiate oscillation. First, the amplitude of the oscillatory signal detected by the Analog-to-Digital Converter (ADC) is calculated. This amplitude is subsequently amplified by a predetermined factor and multiplied with the ADC-detected signal. The resultant product serves as the input for the digital-to-analog converter, facilitating the generation of a drive signal for the MRHG. Upon the oscillation amplitude attaining a specified threshold, the control system transitions the drive control to the Direct Digital Synthesis (DDS) module. Concurrently, we employ a high-frequency clock to measure the frequency of the ADC sampling signal. The measured frequency is then used to establish a reference frequency range for the Proportional-Integral-Derivative (PID) controller, with the aim of expediting the convergence speed. Finally, a PID block based on the standard IEEE-754 floating-point format is implemented to perform fine-grained adjustment of the DDS frequency control word. Experimental results demonstrate that the amplitude control shows a variation of ±1% with respect to the reference value. For MHRGs with different Q factors and resonant frequencies, the phase error between the drive and detection signals is maintained within ±0.5°.

The coded-aperture gamma camera has significant applications in the fields of space exploration, nuclear security, nuclear industry, and nuclear medicine. The coded-aperture collimator is a key component for modulating gamma rays, and its parameters are important factors to optimize the performance of gamma cameras. In this paper, the impact of collimator thickness on the fully coded field of view and angular resolution was determined through Monte Carlo simulation and experimental verification. By introducing the equivalent thickness, the conventional calculation formulas were modified to improve the calculation accuracy. In addition, the variation in the reconstructed image quality with the collimator thickness was quantitatively evaluated by the contrast-to-noise ratio and normalized mean squared error, thereby establishing the relationship between the gamma-ray transmittance and the imaging quality. The results indicate that for medium- and high-energy gamma rays, the optimal imaging quality is achieved when the gamma-ray transmittance corresponding to collimator thicknesses ranges from 12% to 16%. These research findings provide reference standards for the design of coded-aperture collimators to meet the requirements of different applications.

Continuous wave UV lasers have a plethora of applications in many fields, among others, laser spectroscopy, atom trapping, and other related areas. We present a high power continuous wave UV laser system based on twofold second harmonic generation of IR radiation for cooling bunched relativistic ion beams and laser spectroscopy with an output power exceeding 2.4 W in the UV range. Laser operation in the UV regime is often limited by degradation of β-barium borate (BBO) due to two-photon absorption (TPA). We were able to overcome this issue with a novel design of an elliptically focusing enhancement cavity employing commercially available BBO as the nonlinear medium. Building on previous results, we implemented a novel elliptically focusing enhancement cavity featuring an extreme waist ratio of w0,sag/w0,tan = 27.5 at the center of the BBO crystal, aiming to further reduce the peak intensity. This paper details the results as well as our advanced locking scheme for the enhancement cavities for both second harmonic generation steps.

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.

Scintillation screens are widely used to diagnose high-charge density, low-average current electron beams from laser wakefield accelerators (LWFAs). However, the absolute response between emitted photons and electron charge has only been calibrated at a limited number of facilities, and there have been discrepancies between these calibrations. In this report, we comprehensively revised the absolute charge calibration of two high relative brightness scintillating screens of LANEX Regular (Carestream) and PI200 (Mitsubishi) by employing the high-brightness photoinjector at the National Synchrotron Radiation Research Center (NSRRC), which provides electron beams with variable charges (50–350 pC per pulse) and energies (26.55, 34.50, 42.10 MeV). Our results show that the energy-independent fluorescence efficiency of LANEX Regular and PI200 is (7.39 ± 0.38) × 109 and (2.04 ± 0.04) × 1010 photons/sr/pC, respectively, and both screens retained over 98.5% efficiency at accumulated charge densities up to 500 nC/mm2. These results provide a robust framework for applying the scintillation screens in LWFA diagnostics to enhance accuracy and reliability in electron beam characterization.

This paper reports a compact fiber optical electric field (E-field) sensor aiming for the precise detection of transient E-field distributions. Here, a reflective polarization-reciprocal optical path is proposed, which inherently mitigates the temperature-induced birefringence interference of the electro-optical crystal without the need for additional optical elements, thereby facilitating a reduced-size sensing probe. Furthermore, an adaptive particle swarm optimization (A-PSO) algorithm has been utilized for the first time to optimize the insulation structure of the optical E-field sensor, which significantly suppresses field distortion within the sensing region by 50%. This method addresses the technical gap in optical E-field sensor structure optimization, providing an effective means to improve its spatial resolution. The experimental results demonstrate that the proposed sensor exhibits a broad response frequency range from 50 Hz to 15 MHz, with a sensitivity of 0.675 V/kV cm−1. The proposed sensor successfully monitors the spatial distribution of electric fields in the lightning interception region of a lightning rod, thereby validating its effectiveness.

The atomic processes are important for understanding the mechanisms of divertor detachment physics. The developed diagnostic system for atomic processes aims to present the atomic process distributions of ionization and recombination in the whole divertor region of HL-3, which is equipped with the multi-channel visible imaging optics, two SCMOS cameras having identical parameters, and bandpass filters. This configuration enables high spatiotemporal resolution measurements of Balmer lines across the entire divertor region. The maximum frequency of the cameras is 400 fps (512 pixel × 512 pixel), and the field of view covers the entire 1100 × 650 cm2 area of the divertor with the spatial resolution of 1 × 1 cm2. The intensity ratio of experimental measurements of Balmer lines can be used to assess the leading region of ionization, transition from ionization to recombination, and recombination from the Atomic Data and Analysis Structure database. The preliminary results show that ionization is primarily distributed near the last closed flux surface (LCFS), while the transition from ionization to recombination and recombination predominate within a limited region distant from the LCFS. Through the corresponding S/XB, the numbers of ionization and recombination per unit time within the divertor region are obtained. With the evolution of time, the electron density gradually increases, and the ionization region and ionization rate gradually increase. This holds immense significance in advancing our comprehension of the detachment mechanism, facilitating real-time control of divertor detachment and steady-state control technology of heat load in the future.