Nanosecond pulsed streamer discharge has unique characteristics that differentiate it from longer discharges. The very fast voltage rise time, peak voltage plateau, short pulse duration, and fast fall time enable a large volume of uniform nonthermal plasma generation at atmospheric pressure. This review explains the physics of nanosecond discharge plasma through experimental and simulated studies for plasma processing techniques. The following are discussed and compared between sub-microsecond and nanosecond discharge plasma: discharge phase transition, discharge propagation, production of chemically active species, temperature change of gas during plasma propagation, electrode geometry, effect of voltage rise rate, voltage polarities, and N ₂ /O ₂ gas composition ratio in air seeding gas. Nanosecond pulse discharge plasma is characterized by a considerably faster streamer head propagation velocity and reduced gas heating, resulting in a higher energy efficiency for plasma processing. Ozone generation, nitric oxide treatment and volatile organic compound treatment results are given as examples of plasma processing.

High-voltage technologies, including plasma, are used in agriculture and food processing applications. Repetitively operated, compact high-voltage power supplies with moderate peak power have been developed for controlling discharge plasmas and electric field distribution for agricultural and food processing applications. These applications are mainly based on the biological effects of a spatially distributed electric field and the chemically active species produced by the plasma. The intense pulse electric fields (PEFs) that have biological effects are caused by applying pulse voltage between the electrodes. When the applied voltage exceeds the corona discharge criterion, discharge plasmas that produce free radicals, UV radiation, an intense electric field and shock waves are generated by the accelerated electrons within the intense electric field in a gas or liquid medium. Different high voltages and plasmas may have different biological effects on substrates via the electric field and reactive species. For instance, intense electric fields form pores on the cell membrane (i.e. electroporation) or influence the nucleus. The agricultural applications of plasma are categorized as seed germination promotion, plant growth acceleration, the inactivation of bacteria in soil and liquid hydroponic media, and the promotion of fruit-body formation such as in mushrooms and fruits in the pre-harvest phase. In the postharvest phase, maintaining the freshness of agricultural products is important for a sustainable food supply chain. High-voltage and plasma technologies can contribute to maintaining freshness by decontaminating the air and liquid in agricultural products storage containers. In the food processing phase, an intense PEF can be used to extract juice, nutritional agents and antioxidant metabolites such as vitamin, carotenoids and polyphenols from fruits and vegetables. Some foods and liquors are made by fermenting a food substance. Fermentation is a metabolic process enabled by yeast and bacteria, the activity of which can be controlled by an intense electric field.

To meet the needs of the hungry population, it is critical to boost agricultural product production while minimizing contaminated waste. The use of two nonthermal technologies, pulsed electric field (PEF) and nonthermal plasma (NTP), is increasing every day. As both PEF and NTP are relatively newer areas, there is limited knowledge about these two technologies and their modes of action. Studies showed that PEF treatment on the plant seeds helps germination and seedling growth. The positive impact of PEF intensity is highly dependent on the seed coat type and plant species. Another nonthermal technology, NTP, affects seed germination, seedling growth, yield, and resilience to abiotic stress when generated at varying pressures with and without different feed gases. Early germination, germination rate, and germination percentage were all improved when the seedlings were treated with NTP. Similarly to the PEF treatment, NTP had a negative or no effect on germination. This review examined the effects of PEF and NTP on seed germination and analyzed the situation and mechanism behind the positive or negative effect. Deactivation of proteins and enzymes to extend the shelf life of beverages is another prominent application of PEF and NTP. The interaction of PEF and NTP with proteins aids in understanding the microscopic mechanism of these technologies. Therefore, we covered in this review the potential structural and functional changes in proteins/enzymes as a result of PEF and NTP, as well as a comparison of the benefits and drawbacks of these two technologies.

This study investigates the effects of voltage rise rates from 0.1 kV ns ⁻¹ to 100 kV ns ⁻¹ on streamer discharge in air at atmospheric pressure using numerical simulation. The curvature of the needle electrode is also used as an input parameter to change the streamer inception voltage and the average voltage, V _ave , during streamer propagation. The results show that the streamer propagation velocity, v _pri , the electric field strength at the streamer head, E _h , the diameter of the streamer channel, and the O radical production characteristics during the primary streamer propagation are dependent on V _ave . v _pri and E _h exhibit different effects on V _ave / d , where d is the gap distance of the electrode, which indicates that the streamer remains in the transient state from the filament-type discharge to the diffuse-type discharge. The comparison between the simulation and experimental results shows that the simulated v _pri characteristics are in good agreement with the experimental results, regardless of the voltage waveform and electrode configuration, which indicates that V _ave / d has a strong correlation with the primary streamer characteristics.

Recent years have seen numerous studies into how applying pulsed high electric fields (PEF) to living organisms induces various stress reactions. Plants produce glucose through photosynthesis and use this as a source of energy for living, yet there are few studies on the photosynthetic response characteristics when PEF is applied to growing plants. In this study, the photosynthetic response when electric fields of 10 to 100 V/mm were applied to light and dark-acclimated leaves of lettuce was measured by combined gas exchange and chlorophyll fluorescence, and the exposure time was kept constant at 500 s. The responses to PEF with regard to the photosynthetic parameters of electron transfer rate (ETR), non-photochemical quenching (NPQ), photosynthetic rate (A), and transpiration rate (E) were recorded during the experiment. Results showed that PEF can cause both the activation and deactivation of photosynthetic activity in lettuce, that there is an optimum value for activation, and that the application of excessive energy leads to inactivation. This study also found that stomata on both active and deactivated lettuce had been open to a greater extent than lettuce to which PEF had not been applied. All the results of statistical significance in this study were p < 0.05 and p < 0.01.