Liquid spray transport of air–plasma-generated reactive species toward plant disease management

Abstract

Liquid–phase transport of plasma-generated reactive species toward large-scale plasma treatment for agricultural applications is experimentally studied. The liquid-phase reactive species in this study are generated by the contact of water solution with air–plasma effluent gas containing mainly low-solubility reactive species under elevated pressure, followed by spraying the plasma effluent gas dissolved solution into a target pathogenic conidium suspension. Low-solubility ozone in the liquid phase at the target is found to dominate the observed germination suppression effect, which also correlates with the gas-phase ozone density. The measured ozone concentration at the target is found to be ten times lower than the ozone concentration at saturation, estimated from Henry’s law with the measured gas-phase ozone density. The liquid-phase ozone loss mechanism during the transport of the sprayed liquid is interpreted as volatilization and reactions with co-dissolved species. The deduced control parameters for precise ozone transport are the droplet diameter of the sprayed solution, sprayed jet flow, and co-dissolved reactant with the liquid-phase ozone such as nitrite.

Portable Plasma Device for Electric N2O5 Production from Air

“…Compressed air stored in the cylinder is supplied to the HT and LT plasma reactors, and both air flow rates are fixed at 1 L/min. The electric field in the air discharge plasma selectively heats the electrons to ∼10 4 K, leading to molecular dissociation to form radicals and subsequent reaction products. − The HT plasma reactor, designed to elevate the gas temperature with the discharge coupling power and heat recovery, mainly exhausts nitric oxide (NO) and nitrogen dioxide (NO 2 ). The LT plasma reactor, designed for lower power and a large heat loss to avoid nitrogen dissociation and to enhance O 3 production yield, ,,, mainly exhausts O 3 .…”

“…The PFA tube is used to increase the reaction time ( t mix ) of the mixture gas up to 24 s, of which the length and inner diameter are varied for analytical purposes. The plasma effluent mixture is flown through a gas cell with a 5 m long optical path for Fourier-transform infrared (FT-IR) absorption spectroscopy for reactive species analysis as described in our previous works. , …”

“…The plasma effluent mixture is flown through a gas cell with a 5 m long optical path for Fourier-transform infrared (FT-IR) absorption spectroscopy for reactive species analysis as described in our previous works. 9,10 Figure 2 shows the optical images, schematic drawings, and characteristics of the portable plasma module (W700 mm × H 250 mm × D 155 mm), powered by a general AC power input. The HT plasma reactor has double concentric glass/quartz tubes (OD: 12 mm, ID: 10 mm/OD: 6.1 mm, ID: 4.1 mm) for heat exchange and dielectric barrier discharge (DBD).…”

Towards prevention and prediction of infectious diseases with virus sterilization using ultraviolet light and low-temperature plasma and bio-sensing devices for health and hygiene care

“…An air plasma-effluent-gas dissolved solution (PEGDS) spray device has been developed. 52) The PEGDS spray device relies on dissolution of the plasma effluent gas into distilled water for practical use in the public health and agricultural fields. The performance of the PEGDS device is characterized by the suppression of conidial germination of plant pathogens, and the reactive species are generated in both the gas and liquid phases.…”

Experimental detection of liquid-phase OH radical decay originating from atmospheric-pressure plasma exposure

“…This experimental detection and the deduced quantification of the rapid •OH decay suggests a surface localization of •OH, and thus can be an important finding to characterize the inhomogeneous •OH distribution. © 2021 The Japan Society of Applied Physics Supplementary material for this article is available online N ovel applications of non-equilibrium atmosphericpressure plasmas (APPs) in a liquid or in contact with a liquid have been found in medicine, [1][2][3][4][5] agriculture, [6][7][8][9][10] materials synthesis, 11,12) and waste water treatment. [13][14][15] Many of these utilize APP as a source to deliver reactive oxygen and nitrogen species (RONS) into the liquid phase, while much of the RONS chemistry at the plasma-liquid interface has not been well understood.…”