Regulating the parameters of the atmospheric pressure plasma jet (APPJ) is meaningful for industrial applications. Since plasma is a typical functional fluid in the magnetic field, it is possible to control the discharge characteristics via the Lorentz force. In this study, the effects of a locally divergent magnetic field on the generation and propagation of APPJ were examined experimentally. The experiments used a coplanar dielectric barrier discharge (CDBD) device driven by a 30 kHz AC high-voltage source to generate a helium APPJ. A locally divergent magnetic field of 250 mT (maximum) was applied coupled with the electric field, and noticeable enhancement was observed. The results showed that the magnetic field changed the motion state of electrons and promoted collision ionization, leading to a 40% improvement in the APPJ length (0.6 cm) and a 23% increase in the intensity of line O (777.2 nm). In addition, the spatiotemporal evolution and flow field of APPJ were diagnosed by ICCD and schlieren technique. The combination of electric and magnetic fields may effectively optimize the APPJ in practical applications.

This paper explores the aerodynamic characteristics of the He plasma jet under nanosecond pulse needle-ring discharge excitation (dielectric-barrier), and the influence of typical pulse parameters on the flow field is preliminarily ascertained. Schlieren photography is employed to visualize the flow field of the jet, and dynamic processes from plasma generation to post-discharge evolution are recorded in detail by a high-speed camera. The visualized images reveal a transition from a laminar to a turbulent region in the flow field outside the tube following discharge excitation. The turning point (turbulent vortex) propagates at a speed of m/s. The results show that a higher driving voltage leads to an earlier onset of the turbulent vortex and further shortens the laminar zone length, with a maximum reduction of 36%. The turbulent vortex dynamics gradually diminish as the frequency increases, resulting in a maximum 30% reduction in the laminar zone length after the cumulative effect of several cycles. Also, the impact of the pulse width parameter on the flow field is minimal. By observing the changes in the distribution of gas temperature under different discharge parameters, it is concluded that the thermal effect is the main factor influencing the kinetic process of the flow field.

The electrohydraulic discharge is an effective and safe method to carry out laboratory simulations of underwater explosion effects. This work made a detailed comparison study on electrical and fluid characteristics of underwater pulsed discharge (UPD) and underwater electrical wire explosion (UEWE). High-speed photography synchronized with optical-electrophysical diagnostics has been applied to understand the multi-physical process. The results exhibit obvious differences between the two approaches. Under 6.4 J stored energy, the energy deposited into UEWE load can reach 3.34 J (η>50%), which is 2.4 times higher than that of UPD. The electric power peak is ∼14.69 MW for UEWE, while ∼500 kW for UPD. Under atmospheric pressure, the diameter of UEWE bubble of its 1st pulsation can reach 25.6 mm, while UPD is only 19.5 mm. Accordingly, the expansion rate of UEWE bubble can reach 51 m/s (UPD of 42 m/s). Further increase the stored energy to 12.1 J, the maximal size of UEWE bubble reaches 31 mm (potential energy 1.56 J). Morphologically, the UPD bubble is initially irregular, determined by the pre-developed streamer, whereas UEWE exhibits typical cylindrical-spherical evolution process. In later stage of bubble evolution (collapse and 2 ^nd pulsation), the UPD bubble remains regular, whereas UEWE bubble appear irregular shape with spikes. When elevate or increase the ambient pressure, the maximal radius of the bubble decreases or increases accordingly. Particularly, the shock waves of the whole oscillation of UEWE bubble are detected in the sound-absorbing water tank, with values of 274.3 kPa, 105.4 kPa, and 47.9 kPa, respectively.

The widespread use of small unmanned aerial vehicles (UAVs) has increased the need for reliable short-range detection in complex environments. Interactions between the vehicle surface, air, and suspended particles can accumulate charge and generate an electrostatic field, providing a passive signature independent of external radiation. This study develops a quantitative triboelectric charging model based on kinetic gas theory. A shielded high-speed airflow impact experiment estimated an equivalent charge-transfer parameter for the tested carbon-fiber composite and airflow, with an adjusted coefficient of determination (adjusted R²) of 0.967. Flow-field, dilute gas–solid two-phase, and multiphysics electrostatic simulations were then used to determine surface charging and near-field characteristics. Flight encounter tests employed an induced-current electrostatic detector and a MEMS electric-field sensor. At 30 m/s, the simplified model predicted a total charge on the order of 10⁻⁷ C and a 3.8% variation from 0° to 20° angle of attack. The maximum electric-field strength along the nominal 10 m encounter trajectory was 415 V/m. After filtering and temporal alignment, the measured and simulated electric-field rates of change had an adjusted R² of 0.980 for the selected encounter, while the MEMS measurements yielded a shape-consistency coefficient of 0.937. The encounter measurements provide preliminary support for the predicted response trend under the tested conditions and a quantitative framework for analyzing the electrostatic near-field signatures and passive detection of small UAVs. The method may serve as a complementary means of short-range UAV detection.