Plasma fluidized-bed contributes to strengthening the interaction between active species in plasma and fluidized powder particles, resulting in higher active species utilization efficiency and superior powders processing/modification performance. However, the plasma streamer dynamics on the fluidized powder particles are still unclear due to the intricacy of plasma fluidized-bed. In this work, the time-resolved evolution behavior of plasma streamers on fluidized powder particles surfaces has been explored in plasma fluidized-bed system based on a simplified pin-cylinder configuration. The results reveal that the entire streamer propagation process includes volume discharge and surface discharge. The maximum electron density generated by surface discharge is one order of magnitude higher than that produced by volume discharge, indicating that surface discharge plays a dominant role in powder particles modification. The presence of fluidized particle will cause streamer branching, and the main streamer splits into two independent sub-streamers for propagation in a ‘parabola-like’ shape. Compared with large-size fluidized particles (1000 µm), streamer wraps a larger area on micron-size fluidized particles (200 µm), with a 78% increase in the coverage area, which is favorable to the modification of powder particles. Furthermore, the evolution of active species on fluidized particle surface is analyzed. The active species (N, O, O₂ ⁻) are mainly distributed around the north pole, and N₂ ⁺ is mainly distributed between 25° and 50° of the particles. With the decrease of fluidized particle size, the polarization effect between particles is significantly enhanced, and the maxima of the number densities of active species increase. These findings help to get a better understanding of the interaction between plasma and fluidized particles in fluidized systems.

The enhancement of plasma generation in atmospheric pressure dielectric barrier discharge (DBD) is gaining increasing interest for various plasma applications. In this paper, the effect of surface charges moving with the rotating dielectric plate on improving the generation of streamer channels is investigated by a statistical analysis of electrical measurements, optical diagnostics, and numerical simulation in a needle-plate DBD device with a rotating dielectric plate. Results suggest that rotating the dielectric plate can improve the spatiotemporal distribution of streamer channels by inducing a bending of the streamer channels and an increase in the number of discharges. Statistical results show that the number of current pulse and discharge energy are increased by 20% and 47%, respectively, at the rotating speed of 160 rps (revolution per second). Based on the interaction between the applied electric field and the electric field induced by surface charges, a formula is proposed to govern the effect of rotating the dielectric plate on the discharge energy and streamer bending. To further understand the mechanism of the influence of rotating the dielectric plate on plasma properties, a 2D fluid model is implemented, and the reduced electric field and streamer propagation are analyzed. Results show that the effective transfer and reuse of surface charges play an important role in the enhancement of plasma generation.

A dual‐frequency (DF) dielectric barrier discharge, excited by the superposition of a 50 Hz low frequency (LF) and a 5000 Hz intermediate frequency (IF), is proposed to enhance discharge. The effect of the LF voltage component on the breakdown behaviour of the DF discharge during different periods has been studied both experimentally and numerically. The number of high‐current pulses rises as the LF voltage increases. The statistical analysis shows that the number of the current pulse amplitude above 80 mA in the DF discharge reaches nearly 6 times that in the IF discharge. Additionally, the total discharge energy in the DF discharge is significantly higher than that in the IF discharge. The simulation reproduces the temporal variation of the breakdown behaviours in the DF discharge. The simulated results reveal that the maximal electric field strength of the breakdown process is greater in the DF discharge compared to the IF discharge during a half‐period of DF. Finally, the comparison between the IF and DF discharges exhibits that the LF voltage regulates the accumulation of residual charged species on the dielectric surface after the breakdown by modulating the residual voltage between the air gap.

Exploration of the interaction dynamics between plasma and fluidized particles in a plasma fluidized-bed holds practical importance for elucidating the mechanism of plasma treatment of powders. In this study, we employed a 2D fluid model to investigate the effects of particle diameter, dielectric constant, and inter-particle spacing, with the primary aim of simulating the specific consequences of variations in particle size, material type, and gas-to-powder ratio (GPR) on the powder processing effect. The results indicate that particles with diameters below 300 μm exert less impact on streamer propagation, enabling complete plasma wrapping of the particle surface (100%). However, particles with a diameter of 400 μm induce branching, leading to a reduction in the treatment area to 46%. These observations imply a critical particle size range of 300–400 μm for achieving effective plasma treatment of the fluidized particles. Plasma treatment ensures a comprehensive surface coverage on particles with low dielectric constants (εr8) exhibit a diminished plasma-treated surface area (80%), meaning that longer treatment durations for high dielectric constant materials may be required to achieve a comparable treatment effect. Furthermore, as the inter-particle spacing increases from 10 to 500 μm, the plasma-treated surface area undergoes an initial increment, followed by a subsequent reduction. Notably, at 300 μm spacing, the streamer channel displays a root-like branching pattern, leading to a substantial expansion of the plasma-treated surface area. This indicates that an optimal GPR in the fluidized-bed system can enhance the powder treatment effect.