Evolution of the electron-to-ion temperature ratio of cold plasma in the lobes

The electromagnetic ion-cyclotron (EMIC) instabilities with isotropic ion beam and general loss-cone distribution of cold and hot core plasmas are discussed. The growth rate, parallel and perpendicular resonance energies of the electromagnetic ion-cyclotron waves in a low β (ratio of plasma pressure to magnetic pressure), homogeneous plasma have been obtained using the dispersion relation for cold and hot plasmas. The wave is assumed to propagate parallel to the static magnetic field. The whole plasma is considered to consist of resonant and non-resonant particles permeated by isotropic ion beam. It is assumed that resonant particles and ion beam participate in energy exchange with the wave whereas non-resonant particles support the oscillatory motion of the wave. We determined the variation in energies and growth rate in cold and hot plasmas by the energy conservation method with a general loss-cone distribution function. The thermal anisotropy of the core plasma acts as a source of free energy for EMIC wave and enhances the growth rate. It is noted that the EMIC wave emissions occur by extracting energy of perpendicularly heated ions in the presence of up flowing ion beam and steep loss-cone distribution in the anisotropic magnetosphere. The effect of the steep loss-cone distribution is to enhance the growth rate of the EMIC wave. The heating of ions perpendicular and parallel to the magnetic field is discussed along with EMIC wave emission in the auroral acceleration region. The results are interpreted for the space plasma parameters appropriate to the auroral acceleration region of the earth's magnetoplasma.

Cold plasma technology has found favour in the agricultural industry for growth stimulating by environmental friendly approach. However, there are still leaking studying of cold plasma technology on the mushroom needs. Current convectional mushrooms germination process requires long duration (∼6 weeks) for fruiting to growth. Therefore, this study aims to investigate the cold plasma efficacy towards the oyster mushroom germination speed and fruiting body production. By using novel atmospheric cold plasma pen system, the mushroom spawn grains were generates towards the spawn. Atmospheric pressure with flow rate of 4, 5 and 6 SLM by considering different duration plasma exposure (0, 5, 15, 30, 45 and 60 seconds) with ∼7 kV of supply voltage was supplied. The efficiency of the treatment was characterised by mushroom cultivation performance particularly on (i) mycelium growth rate and (ii) mushroom fruiting body productions. The results show cold plasma processing parameter, flow rate and treatment time absolutely influence the mushroom germination and production. CP pen system optimized at 5 SLM and 15 s presents triple production of mushroom weight and speed the mycelium growth rate (only 4 weeks) compared to control spawn grains (6 weeks). As conclusion, cold plasma pen system capability applies in mushroom industry.

Two-point transport model for cold divertor plasmas

Cold plasma pretreatment for transforming fruit and vegetable waste: A comprehensive review

In 1995, the Galileo spacecraft traversed the wake of Io at ∼900 km altitude. The instruments onboard detected intense bi‐directional field‐aligned electron beams (∼140 eV–150 keV), embedded in a dense, cold and slow plasma wake (Nel ∼ 35,000 cm−3, Ti < 10 eV, V < 3 km/s). Similar electron beams were also detected along subsequent Galileo flybys. Using numerical simulations, we show that these electron beams are responsible for the formation of Io's dense plasma wake. We prescribe the composition of Io's atmosphere in S, O, SO and SO2, compute the atmospheric ionization by the beams with a parameterization adapted from study of auroral electrons at Earth, the plasma flow into Io's atmosphere with a Magneto‐Hydro‐Dynamic code, and the ion composition and temperature with a multi‐species physical chemistry code. Results reveal contrasting chemistries between the upstream and wake regions, leading to different ion compositions. The upstream chemistry is driven by the torus thermal electrons at 5 eV with SO2+ becoming the dominant ion because of electron‐impact ionization of the SO2 atmosphere. The wake chemistry is driven by the high‐energy electrons in the beams with S+ and SO+ becoming the dominant ions produced by dissociative‐ionization of SO2. We show that the wake ion composition is highly sensitive to the atmospheric composition. Juno, in its extended mission, will traverse Io's wake and determine its ion composition, which, compared with our numerical simulations will enable us to infer the detailed composition of the atmosphere.

Dust Wake in a Collisional Plasma

The analysis of cold plasma stabilization of the drift-cyclotron-loss-cone mode in mirror machines is extended to conditions in which the cold plasma is confined by a weak local minimum in the ambipolar potential. These conditions allow stabilization with less electron energy drain than simple axial flow of cold plasma. Scaling laws are derived for the required cold plasma flux, the resulting fluctuation induced ion diffusion, the steady state electron temperature, and the trapped-ion lifetime.

When a high-speed aircraft flies through the atmosphere, the plasma sheath and plasma wake can significantly affect electromagnetic wave signals. To investigate the impact of the plasma sheath and wake on radar imaging, this paper first develops a linear frequency modulated continuous wave radar array signal echo model for the full target (body, plasma sheath, and plasma wake). The model effectively considers the spatial distribution characteristics of the dielectric constant and velocity in the plasma flow field. Subsequently, 2D range-Doppler images and 2D range-angle images of full targets were studied, using a joint range-velocity-angle estimation algorithm at different frequencies and altitudes. The research results show that at an altitude of 40 km, with incident frequencies from 1 to 3 GHz, the signals of the body and its wake are stronger at 1 GHz, which is favorable for full target imaging. In contrast, at 3 GHz, the wake signals are obviously weakened, allowing the body to be extracted almost separately, which is more favorable for target identification and tracking. Similarly, at 1 GHz, the wake signal gradually weakens as the altitude increases from 40 to 70 km. At 40 km, the full target is imaged more clearly. Furthermore, under the conditions of this paper, the variation of parameters has a smaller effect on the angle direction and a larger effect on the range direction. This research provides a theoretical basis for the improvement of radar detection technology, especially in the plasma environment, which provides a valuable reference.

The process of oxidation of molecular nitrogen by high-energy oxidants, such as nitric acid vapor, products of the thermolysis of nitric acid, and hydrogen peroxide, in a cold plasma stream was studied. To implement the process of obtaining nitric acid from atmospheric air using reproductive technology (Zakharov's method), the design of a reactor for obtaining nitrogen oxides by direct oxidation of nitrogen in a cold plasma stream is proposed. At the same time, it was proposed to use the effect of obtaining nitrogen oxides in an air mixture with nitric acid vapors (the Karavaev effect) and during the thermal decomposition of hydrogen peroxide with atmospheric nitrogen (the Nagiev effect). The effectiveness of the use of cold plasma for the oxidation of atmospheric nitrogen was established, which is confirmed by the obtained dependences. It is shown that the amount of nitrogen oxides that are formed depends on the efficiency of the formation of a stable flow of OH- radicals in the plasma flow. It was also found that the amount of nitrogen oxides depends on the parameters of the plasma generator, the composition of the liquid used in the burner, and the amount of air supplied. The effect of nitric acid, hydrogen peroxide, and alcohols as activators of atmospheric nitrogen oxidation in a high-energy field was revealed. It was determined that when comparing three activator substances, which are able to form OH- radicals during their decomposition, it is hydrogen peroxide that is the most promising activator substance for carrying out the process of atmospheric nitrogen oxidation in the plasma flow. The amount of nitrogen oxides formed in the cold plasma region is almost independent of the flow rate of the reaction mixture through the reactor and remains almost unchanged in a wide range of changes in flow rates from 30 to 3000 l/h

The propagation of whistler mode wave packets in a cold magnetospheric plasma is investigated in the quasi‐resonant regime (near the oblique lower hybrid resonance) using the ray approximation. The analysis is essentially simplified by introducing a special curvilinear orthogonal coordinate system (resonant coordinate system (RCS)), which is naturally adapted to the description of the propagation of quasi‐electrostatic waves in a cold plasma, when the group velocity and the wave vector tend to be orthogonal to each other in the deep quasi‐electrostatic limit. It is shown that in an overdense plasma of the Earth plasmasphere, the parameters of the RCS are independent of the space density distribution of the background plasma. The general expressions for the Hamiltonian and whistler wave field intensity focusing law in a deep quasi‐resonant regime are derived.

A fundamental question that is important for the understanding of plasma processes concerns charged particles and plasma interactions. For moving particles (test objects in a plasma flow), these include the formation of plasma wakes. The plasma flow provides not only a direct dragging influence, but is also responsible for the generation of associated collective plasma processes, and the plasma wake can strongly affect interactions between charged objects themselves and the plasma. An example is the interaction between dust particles in the plasma sheath, where ions flowing to the electrode form the ion wake behind negatively charged grains. Here, a number of phenomena starting from the well-known case of a negatively charged body moving in a plasma (or immersed in a plasma ion flow) are briefly discussed. Most emphasis is given to recent results including, in particular, an absorbing moving object and a classical object in a quantum plasma.

Inner magnetosphere magnetic field and plasma flow data are examined during 228 steady magnetospheric convection events. We find that the BZ component of the magnetic field around geostationary orbit is weaker than during average conditions and the plasma flow speeds are higher than average in the dusk sector just beyond geostationary orbit. The steady magnetospheric convection periods include more enhanced earthward and tailward flow intervals than during average conditions. The steady convection period magnetic field is not steady: The near‐geostationary nightside field grows increasingly taillike throughout the steady convection period. In the midtail, earthward flows are enhanced in a wide region around the midnight sector, which leads to enhanced magnetic flux transport toward the Earth during the steady convection periods. Compared to well‐known characteristics during magnetospheric substorms, the inner tail evolution resembles that during the substorm growth phase, while the midtail flow characteristics during steady convection periods are similar to those found during substorm recovery phases.

Addition of cold plasma to the magnetosphere outside the plasmasphere can enhance both ion and electron electromagnetic cyclotron (EMC) instabilities. To turn on the ion EMC mode, one needs a cold plasma ion which is not too heavy; in many respects, lithium is ideal. Calculations have been made of total ion-EMC amplification on a single pass through a lithium cloud; these show that as much as 40–80 dB gain can be achieved on a synchronous-orbit field line. The most important effects of adding lithium are to reduce the minimum anisotropy requirement considerably, and to broaden the unstable domain in k-space. The dynamics of the cold lithium cloud have been studied in detail; on a time scale of a few hours, the cloud behaves as an incompressible fluid in the presence of electric convection fields, and should not become so seriously distorted that the total amplification given above is substantially degraded. Some remarks are made about the effects of added cold plasma on the Post-Rosenbluth electrostatic mode; for the most part, growth rates are reduced with addition of cold plasma.

Creation of silicon submicron structures by compression plasma flow action

Saturn’s moon Rhea is thought to be a simple plasma absorber, however, energetic particle observations in its vicinity show a variety of unexpected and complex interaction features that do not conform with our current understanding about plasma absorbing interactions. Energetic electron data are especially interesting, as they contain a series of broad and narrow flux depletions on either side of the moon’s wake. The association of these dropouts with absorption by dust and boulders orbiting within Rhea’s Hill sphere was suggested but subsequently not confirmed, so in this study we review data from all four Cassini flybys of Rhea to date seeking evidence for alternative processes operating within the moon’s interaction region. We focus on energetic electron observations, which we put in context with magnetometer, cold plasma density and energetic ion data. All flybys have unique features, but here we only focus on several structures that are consistently observed. The most interesting common feature is that of narrow dropouts in energetic electron fluxes, visible near the wake flanks. These are typically seen together with narrow flux enhancements inside the wake. A phase-space-density analysis for these structures from the first Rhea flyby (R1) shows that Liouville’s theorem holds, suggesting that they may be forming due to rapid transport of energetic electrons from the magnetosphere to the wake, through narrow channels. A series of possibilities are considered to explain this transport process. We examined whether complex energetic electron drifts in the interaction region of a plasma absorbing moon (modeled through a hybrid simulation code) may allow such a transport. With the exception of several features (e.g. broadening of the central wake with increasing electron energy), most of the commonly observed interaction signatures in energetic electrons (including the narrow structures) were not reproduced. Additional dynamical processes, not simulated by the hybrid code, should be considered in order to explain the data. For the small scale features, the possibility that a flute (interchange) instability acts on the electrons is discussed. This instability is probably driven by strong gradients in the plasma pressure and the magnetic field magnitude: magnetometer observations show clearly signatures consistent with the (expected) plasma pressure loss due to ion absorption at Rhea. Another potential driver of the instability could have been gradients in the cold plasma density, which are, however, surprisingly absent from most crossings of Rhea’s plasma wake. The lack of a density depletion in Rhea’s wake suggests the presence of a local cold plasma source region. Hybrid plasma simulations show that this source cannot be the ionized component of Rhea’s weak exosphere. It is probably related to accelerated photoelectrons from the moon’s negatively charged surface, indicating that surface charging may play a very important role in shaping Rhea’s magnetospheric interaction region.