講演情報
[16p-K304-16]Suppression of Instability in High-Speed Water Jet by Plasma Exposure
〇Kalyani Barman1, Kazuki Takeda1, Shota Sasaki1, Toshiro Kaneko1 (1.Tohoku Univ.)
キーワード：
plasma-water interface、Plateau-Rayleigh Instability
Atmospheric pressure plasma jets are widely used in biomedical fields and agriculture. Reactive oxygen and nitrogen species (RONS), produced and transported across the plasma-water interface through complex chemical and physical processes, play a key role in these applications. To achieve an effective control of RONS, it is imperative to study their generation, transport mechanisms, and the behavior of the plasma-water interface.
Surface deformations, such as bulges or thinning regions on the water surface, alter the local geometry of the plasma-water interface. Since the electric field strength is highly sensitive to surface curvature, these deformations cause the electric field to redistribute unevenly, affecting the generation and transport of RONS, reaction kinetics and energy transfer at the interfaces. In this study, we investigated the shape deformation of plasma water interface in a coaxial water jet system, leading to Plateau-Rayleigh instability. The measure of this instability has been determined by the length of the water jet from the nozzle of the tube to the first droplet formation (LB).
Our findings reveal that LB decreases under the influence of an electric field but is partially recovered when both plasma and the electric field are present. The electric field accelerates the onset of instability via Maxwell stress, increasing the growth rate and causing earlier breakup. It is thought that plasma mitigates instability through ion ram pressure, electron pressure, and the shielding effect of the electric field. While previous studies demonstrated stability in low-pressure plasma with a flat plasma-water interface, high-collisionality conditions, such as those in atmospheric pressure plasma and coaxial water jets, likely modify plasma properties, leading to changes in RONS transport at the interface, which require further investigation.
Surface deformations, such as bulges or thinning regions on the water surface, alter the local geometry of the plasma-water interface. Since the electric field strength is highly sensitive to surface curvature, these deformations cause the electric field to redistribute unevenly, affecting the generation and transport of RONS, reaction kinetics and energy transfer at the interfaces. In this study, we investigated the shape deformation of plasma water interface in a coaxial water jet system, leading to Plateau-Rayleigh instability. The measure of this instability has been determined by the length of the water jet from the nozzle of the tube to the first droplet formation (LB).
Our findings reveal that LB decreases under the influence of an electric field but is partially recovered when both plasma and the electric field are present. The electric field accelerates the onset of instability via Maxwell stress, increasing the growth rate and causing earlier breakup. It is thought that plasma mitigates instability through ion ram pressure, electron pressure, and the shielding effect of the electric field. While previous studies demonstrated stability in low-pressure plasma with a flat plasma-water interface, high-collisionality conditions, such as those in atmospheric pressure plasma and coaxial water jets, likely modify plasma properties, leading to changes in RONS transport at the interface, which require further investigation.