Dayside Diffuse Aurora and the Cold-Plasma Structuring: A Brief Review

Diffuse aurora is generated by the precipitation of hot electrons from the central plasma sheet due to wave-particle interaction. Near magnetic local noon (MLN), the diffuse aurora was often observed in structured forms, such as in stripy or patchy. In the magnetosphere, when the hot electrons meet with a cold plasma structure, the threshold of resonance energy for the electrons in the cold plasma region can be lowered, leading to more electrons being involved in the wave-particle interaction and being scattered into the loss cone. As a result, stronger diffuse aurora can be produced in the correspondent region. Based on this mechanism, the structured dayside diffuse auroras have been suggested to correspond to the cold plasma structures in the dayside outer magnetosphere. This brief review focuses on showing that 1) the stripy diffuse auroras observed near MLN are specifically informative, 2) there are two types of diffuse aurora near MLN, which may correspond to cold plasmas originating from inside and outside the magnetosphere, respectively, and 3) we can study the inside-outside coupling by using the interaction between diffuse and discrete auroras observed near MLN.

Selective Apoptotic Effect of Plasma Activated Liquids on Human Cancer Cell Lines

Plasma medicine is a new field focusing on biomedical and clinical applications of cold gas plasmas, including their anticancer effects. Cold plasmas can be applied directly or indirectly as plasma-activated liquids (PAL). The effects of plasma-activated cell growth medium (PAM) and plasma-activated phosphate buffered saline (PAPBS) were tested, using a plasma pen generating streamer corona discharge in ambient air, on different cancer cell lines (melanoma A375, glioblastoma LN229 and pancreatic cancer MiaPaCa-2) and normal cells (human dermal fibroblasts HDFa). The viability reduction and apoptosis induction were detected in all cancer cells after incubation in PAL. In melanoma cells we focused on detailed insights to the apoptotic pathways. The anticancer effects depend on the plasma treatment time or PAL concentration. The first 30 min of incubation in PAL were enough to start processes leading to cell death. In fibroblasts, no apoptosis induction was observed, and only PAPBS, activated for a longer time, slightly decreased their viability. Effects of PAM and PAPBS on cancer cells showed selectivity compared to normal fibroblasts, depending on correctly chosen activation time and PAL concentration, which is very promising for potential clinical applications. This selectivity effect of PAL is conceivably induced by plasma-generated hydrogen peroxide.

Topological phases and bulk-edge correspondence of magnetized cold plasmas

Plasmas have been recently studied as topological materials. However, a comprehensive picture of topological phases and topological phase transitions in cold magnetized plasmas is still missing. Here we systematically map out all the topological phases and establish the bulk-edge correspondence in cold magnetized plasmas. We find that for the linear eigenmodes, there are 10 topological phases in the parameter space of density n, magnetic field B, and parallel wavenumber kz, separated by the surfaces of Langmuir wave-L wave resonance, Langmuir wave-cyclotron wave resonance, and zero magnetic field. For fixed B and kz, only the phase transition at the Langmuir wave-cyclotron wave resonance corresponds to edge modes. A sufficient and necessary condition for the existence of this type of edge modes is given and verified by numerical solutions. We demonstrate that edge modes exist not only on a plasma-vacuum interface but also on more general plasma-plasma interfaces. This finding broadens the possible applications of these exotic excitations in space and laboratory plasmas.

Cold Plasma Systems and Their Application in Surface Treatments for Medicine

In this paper, a review of cold plasma setups and the physical and chemical processes leading to the generation of active species is presented. The emphasis is given to the interaction of cold plasmas with materials used in medical applications, especially medical implants as well as live cells. An overview of the different kinds of plasmas and techniques used for generation of active species, which significantly alter the surface properties of biomaterials is presented. The elemental processes responsible for the observed changes in the physio-chemical properties of surfaces when exposed to plasma are described. Examples of ongoing research in the field are given to illustrate the state-of-the-art at the more conceptual level.

Topological phases, topological phase transition, and bulk-edge correspondence of magnetized cold plasmas

Plasmas have been recently studied as topological materials. We attempt at a comprehensive picture of the topological phases and the bulk-edge correspondence of magnetized cold plasmas. We find that there are 10 topological phases in the parameter space of density n, magnetic field B, and parallel wavenumber k_z, separated by the surfaces of Langmuir wave-L wave resonance, Langmuir wave-cyclotron wave resonance, and zero magnetic field. For fixed B and k_z, only the phase transition at the Langmuir wave-cyclotron wave resonance corresponds to edge modes. A sufficient and necessary condition for the existence of this new type of edge modes is given and verified by numerical solutions. The edge modes fall into four categories characterized by different behaviors of the Fermi arcs. We demonstrate that edge modes exist not only on a plasma-vacuum interface but also on more general plasma-plasma interfaces. This finding broadens the possible applications of these exotic excitations in space and laboratory plasmas.

Plasma injections arising out of dynamic ionosphere

<p>We propose ionospheric plasma injections to the magnetosphere (ionospheric injection) as a new plasma process in the polar ionosphere. The ionospheric injection is first triggered by westward electric fields transmitted from the convection surge in the magnetosphere in association with dipolarization onset. Localized westward electric fields yield electrostatic potential in the ionosphere as a result of differing electron and ion mobility in the E-layer. To ensure quasi-neutrality of ionospheric plasmas, excess charges are released as injections out of the ionosphere, specifically electrons from positive potential region in higher latitudes and ions from negative potentials in lower latitudes. Potential difference on the order of 10 kV in north-south directions produces southward electric fields (100mv/m) at the footprint of the convection surge in both northern and southern hemispheres. Resultant geomagnetic field lines are not in equipotential equilibrium during ionospheric injections but instead develop downward electric fields in positive potential regions in higher latitudes to extract electrons and upward electric fields in negative potential regions in lower latitudes to extract ions. Parallel electric fields can exist in the magnetic mirror geometry of auroral field lines if the magnetospheric plasma follows quasi-neutral equilibrium. Because ionospheric injection has inherent dynamo processes as well as load, we term the polar ionosphere “dynamic ionosphere”.</p><p>Cold plasmas injected out of the dynamic ionosphere are transported along the dynamical trajectories to the magnetosphere conserving the total energy (including electrostatic potentials) and first adiabatic invariant. Electrons/ions traveling in downward/upward electric fields lose perpendicular and lower velocities in parallel component, leaving only the energetic part of ionospheric plasmas collimated along the field lines. Steady-state and one-dimensional dynamical trajectory shows that ion and electron temperatures at the ionosphere initially at 1 eV increased parallel temperatures to 202 eV and decreased perpendicular temperatures to 0.001 eV at geosynchronous altitudes where the electrostatic potential difference between ionosphere and magnetosphere was assumed to be 200 V. When potential difference increased to 600 V, the parallel temperatures increased to 602 eV, while perpendicular temperatures remain unchanged. Parallel potentials preferentially heated the ionospheric cold plasmas in parallel directions and transported tailward to feed the magnetosphere.</p>

Effects of Non-Thermal Plasma on Yeast Saccharomyces cerevisiae

Cold plasmas generated by various electrical discharges can affect cell physiology or induce cell damage that may often result in the loss of viability. Many cold plasma-based technologies have emerged in recent years that are aimed at manipulating the cells within various environments or tissues. These include inactivation of microorganisms for the purpose of sterilization, food processing, induction of seeds germination, but also the treatment of cells in the therapy. Mechanisms that underlie the plasma-cell interactions are, however, still poorly understood. Dissection of cellular pathways or structures affected by plasma using simple eukaryotic models is therefore desirable. Yeast Saccharomyces cerevisiae is a traditional model organism with unprecedented impact on our knowledge of processes in eukaryotic cells. As such, it had been also employed in studies of plasma-cell interactions. This review focuses on the effects of cold plasma on yeast cells.