This paper provides perspectives on recent progress in understanding the physics of devices in which the external magnetic field is applied perpendicular to the discharge current. This configuration generates a strong electric field that acts to accelerate ions. The many applications of this set up include generation of thrust for spacecraft propulsion and separation of species in plasma mass separation devices. These “E × B” plasmas are subject to plasma–wall interaction effects and to various micro- and macroinstabilities. In many devices we also observe the emergence of anomalous transport. This perspective presents the current understanding of the physics of these phenomena and state-of-the-art computational results, identifies critical questions, and suggests directions for future research.

The cold atmospheric pressure plasma jet interaction with the bio-target is studied in the plasma experiment, 2D fluid model simulations, and with MTT and iCELLigence assays of the viability of cancer cells. It is shown, for the first time, that the use of the grounded substrate under the media with cells considerably amplifies the effect of plasma cancer cell treatment in vitro. Plasma devices with cylindrical and plane geometries generating cold atmospheric plasma jets are developed and tested. The sequence of the streamers which forms the plasma jet is initiated with a voltage of 2.5–6.5 kV applied with the frequency 40 kHz. We suggest using the grounded substrate under the bio-target during the plasma jet treatment of cancer cells. The analysis of the measured plasma spectra and comparison of OH-line intensity for different voltages and gas flow rates allows us to find a range of optimal plasma parameters for the enhanced OH generation. The time-dependent viability is measured for human cell lines, A431 (skin carcinoma), HEK 293 (kidney embryonic cells), and A549 (human lung adenocarcinoma cells) after the plasma jet treatment. The results with cell-based experiments (direct treatment) performed with various plasma jet parameters confirm the maximum efficiency of the treatment with the optimal plasma parameters.

Plasma devices generating a sequence of streamers over an inert gas jet in ambient air have been widely used recently in anticancer therapy. An enhancement of electric field carried by the streamers to the target surface is a way to intensify the plasma jet impact on a cell life cycle. In this paper, an increase of the surface electric field without a rise of discharge power is provided with an external biased electrode installed between the plasma device and target. The effect of the presence of this biased electrode on cathode-directed streamer dynamics and its interaction with conductive or charged dielectric surfaces are studied in 2D fluid model simulations and in the experiment. Two stages of the ionization process induced by the streamer near the plasma–target interface are observed in the experiment and simulations. The first stage is related to the streamer approaching the surface. The second stage is the stationary self-sustained ionization and lasts much longer during a positive cycle of sinusoidal voltage applied to the electrode inside of the plasma device. A much higher surface electric field is registered on the dielectric surface compared to the conductive one, due to an accumulation of the surface charge, especially with the negative bias on the external electrode. An area on the dielectric surface exposed by the plasma jet is much larger compared to the conductive one, due to spreading the surface ionization wave over the dielectric.

The application of cold atmospheric plasma (CAP) in cancer therapy could be one of the new anticancer strategies. In the current work, we used cold atmospheric plasma jet for the treatment of cultured cells and mice. We showed that CAP induced the death of MX−7 mouse rhabdomyosarcoma cells with the hallmarks of immunogenic cell death (ICD): calreticulin and heat shock protein 70 (HSP70) externalization and high-mobility group box 1 protein (HMGB1) release. The intensity of HMGB1 release after the CAP treatment correlated directly with the basal extracellular HMGB1 level. Releasing from dying cells, HMGB1 can act as a proinflammatory cytokine. Our in vivo study demonstrated that cold atmospheric plasma induces a short-term two-times increase in serum HMGB1 level only in tumor-bearing mice with no effect in healthy mice. These findings support our hypothesis that CAP-dependent HMGB1 release from dying cancer cells can change the serum HMGB1 level. At the same time, we showed a weak cytokine response to CAP irradiation in healthy mice that can characterize CAP as an immune-safety physical antitumor approach.

We study the properties of a capacitive 13.56 MHz discharge with a mixture of $\text{Ar}/{\text{C}}_2{\text{H}}_2$ taking into account the plasmochemistry and growth of heavy hydrocarbons. A hybrid model was developed to combine the kinetic description for electron motion and the fluid approach for negative and positive ion transports and plasmochemical processes. A significant change in plasma parameters related to injection of 5.8% portion of acetylene in argon was observed and analyzed. We found that the electronegativity of the mixture is about 30%. The densities of negatively and positively charged heavy hydrocarbons are sufficiently large to be precursors for the formation of nanoparticles in the discharge volume.

The ground-state configurations of a two-dimensional cluster of classical charged particles which are confined by an external ring harmonic potential are determined. With increasing number of particles (N) different structural transitions are found. First, the ring arrangement of particles undergoes a zig-zag transition. Further increasing N, more rings are formed which exhibit one-dimensional crystal-like structures. A normal mode analysis of the ground-state configuration is performed, from which we obtain information on the stability of the ring cluster. © 1996 The American Physical Society.