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Underwater shock wave technology can realize dynamic rock fracture, which is helpful to increase oil and gas reservoir permeability. It can realize the efficient exploitation of medium and low maturity oil and gas resources. In practical application, the shock wave parameters require not only high intensity but also safety and controllability. To meet these requirements, insensitive composite energetic materials driven by electrical wire explosion plasma were proposed, which is one of the most promising methods. However, when in use, the load assembly process containing wires and energetic materials is complex. In this paper, a new type of energetic material load is proposed, using non-penetrating wire to drive composite energetic material. It can simplify the production process of the energetic load and produce acceptable shock wave parameters. The test results show that both the energy deposition of the wire and the shock wave intensity decrease under a non-penetrating wire structure. However, the shock wave intensity is still higher than that of the underwater electrical wire explosion. Based on schlieren diagnosis, it is found that the composite energetic material is gradually driven, and the energy release is not concentrated. In addition, the "non-wire" structure driving condition was discussed in contrast. Under this condition, the process of ionization channel establishment in composite energetic materials is random. The shock wave intensity is weak because the composite energetic material is in the process of slow detonation., (© 2024 Author(s). Published under an exclusive license by AIP Publishing.)

Validated and accurate edge profiles (temperature, density, etc.) are vitally important to the Mega Ampere Spherical Tokamak Upgrade (MAST-U) divertor and confinement effort. Density profile reflectometry has the potential to significantly add to the measurement capabilities currently available on MAST-U (e.g., Thomson scattering and Langmuir probes). This work presents the diagnostic requirements, problems, and solutions facing profile reflectometry in spherical tokamaks and MAST-U in particular. Requirements include density measurements near zero electron density in the scrape off layer region, coverage for a broad range of MAST-U plasma parameters, high time (≤10 microseconds) and spatial resolutions (≤1 cm), reliability, and identification of the plasma start frequency., (© 2024 Author(s). Published under an exclusive license by AIP Publishing.)

A pulsed power supply with a short rise time and high repetition frequency is favorable to driving diffusive plasma for strongly oxidizing radical (O3, OH) generation and increasing the system's energy efficiency. In this paper, a 10-stage solid-state linear transformer driver (LTD) with a nanosecond rise time is developed to drive plasma for wastewater treatment. To decrease the rise time, a control system with low jitter is developed to improve the synchronization of pulses using an optocoupler isolation chip. A 10-stage LTD with a rise time of 6.2 ns is realized in the case that the rise time of the single-stage LTD is 5.4 ns. The results show that the LTD can generate pulses on a 300 Ω resistive load with a repetition frequency of 10 kHz, an amplitude of 8.80 kV, an overshoot less than 3.97%, and a reverse overshoot less than 4.82%. The rise time (6.2-33.0 ns), the pulse width (35.9-200.0 ns), and the fall time (10.5-27.6 ns) can be adjusted flexibly and independently by controlling the drive signals of metal oxide semiconductor field effect transistors. The pulsed generator is utilized to drive plasma in the needle-water electrode system. The preliminary experimental results show that the plasma includes abundant oxygen atoms and hydroxyl radicals with high activity, and it is suitable for wastewater treatment., (© 2024 Author(s). Published under an exclusive license by AIP Publishing.)

Ultra-low noise is a critical component in the design of high-precision sensor front-ends. We introduced differential phase-sensitive detection (d-PSD) to mitigate both multiplicative and additive noise in optical sensors, aiming for an enhanced performance and cost-effectiveness. The d-PSD combines a capacitive transimpedance amplifier (C-TIA), a delta-sigma analog-to-digital converter (ΔΣ-ADC), and a software-based lock-in amplifier (s-LIA). The first two components utilize the DDC112 (a dual current input 20-bit ADC) for a minimal analog channel length, thus reducing noise efficiently, while the latter employs a cost-effective 32-bit microcontroller unit (MCU), the HC32F460. This approach was successfully implemented as the front-end for a smart optical sensor. Testing indicated that the sensor achieved an equivalent current noise level of 0.6 nA/√Hz, primarily attributed to the light source driver rather than the sensor's front-end circuit. The sensor exhibited an exceptional performance, with a 3σ measurement precision of 5.4 × 10-4 over a 1-second integration time and a dynamic range of 100 dB, leveraging the proposed method and design. Furthermore, the front-end of the sensor boasts a compact size, low power consumption, and affordability, making it an ideal, versatile solution for ultra-high precision, smart optical sensors., (© 2024 Author(s). Published under an exclusive license by AIP Publishing.)