Plasma–Liquid Interface Manipulated by Chamber Structure: An Experimental and Theoretical Approach

Abstract

To respond to global challenges of environmental contaminations, pursue more advanced material technologies, and achieve novel biomedical therapies, a variety of plasmas have been applied to wastewater and food processing, biomaterial treatments, and plasma−liquid ignitions. As these applications highly depend on the plasma−liquid interactions, researchers are now focusing on the physical and chemical reactions on the plasma−liquid interface. With massive publications reporting the molecular transfers, chemical pathways, and their effects on plasma treatments, this work provides a new point of view that the plasma−liquid interface can be manipulated by the chamber structure. In the experiment, plasma jet expansion in water is recorded in a cylinder chamber and a stepped-wall one. Data collected from the images show that the stepped-wall structure results in a shorter axial interface propagation, a small volume, more symmetry for the plasma jet, and more stability for the interface. To discover the physical mechanism behind these phenomena, we derived the momentum and energy equations for the plasma−liquid interface during its propagation. Those equations reveal how the stepped-wall structure can be used to manipulate the interface behaviors. Along with our experimental and theoretical investigation of the plasma−liquid interface, such information also sheds light on how the chamber wall structure can be used to manipulate the interface chemical reaction rates, stability, and expansion rate. This work is thus a basis of the future optimization for plasma−liquid treatments and ignitions which will be equipped with a flexible wall controlled by artificial intelligence to automatically achieve a variety of plasma treatment requirements.

Plasma–liquid interactions: an experiment and simulation study on plasma dynamic behaviors near the gas–liquid interfacial layer

“…Moreover, the interface facilitates mass and heat transfer. Temperature gradients at the plasma-liquid interface significantly impact the pathways and reaction rates in this multiphase discharge system, given that most chemical reactions are temperature-dependent [7,8]. To optimize plasma-liquid treatments, a chamber wall structure was designed to manipulate the chemical reaction rates, stability, and expansion rate of the interface [8].…”

“…Temperature gradients at the plasma-liquid interface significantly impact the pathways and reaction rates in this multiphase discharge system, given that most chemical reactions are temperature-dependent [7,8]. To optimize plasma-liquid treatments, a chamber wall structure was designed to manipulate the chemical reaction rates, stability, and expansion rate of the interface [8]. However, the complexity of the reactive species generation with liquid is markedly increased by the effects of liquid surface, such as evaporation and surface deformation, which changes the local gas composition near the gas-liquid interfacial layer [9].…”

On self organization: model for ionization wave propagation with targets of varying electrical properties

“…At these boundaries we specify that species which approach the boundary exit the computational domain. This simulation approach is justified as our experiments are often conducted in controlled environments, where there the background air in the far field region relative to the jet does not have an applied momentum that could interfere with the jet, as could occur in open air in a room with a ventilation system [33,34]. Then, the movement of neutral species in the domain of interest is controlled by the dynamics of the plasma jet and not by any surrounding source of momentum.…”

“…The environment in which these devices operate often include a controlled chamber [33,34]. Instrumentation includes a CCD camera to resolve the microsecond events of ionization waves, light spectroscopy to detect plasma species, capacitance meters to measure jet interaction with cells, and scattering techniques for electron density and temperature.…”

Facile preparation of Bacterial cellulose‐SiO2 composite aerogel with good mechanical strength and thermal stability

“…[4][5][6] However, the fragile "pearl necklace" or "neck" structure inside SiO 2 aerogels leads to poor mechanical properties, limiting its application in practical fields. [7] So far, many technologies, including high-temperature treatment, [8] surface modification, [9] structural regulation, [10] optimization of preparation conditions, [11,12] and skeleton reinforcement, [13] have been used to improve the stability and mechanical properties of SiO 2 aerogels.…”