Explore the vast range of titles available.

Electron temperature is reconsidered for weakly-ionized oxygen and nitrogen plasmas with its discharge pressure of a few hundred Pa, with its electron density of the order of 1017m−3 and in a state of non-equilibrium, based on thermodynamics and statistical physics. The relationship between entropy and electron mean energy is focused on based on the electron energy distribution function (EEDF) calculated with the integro-differential Boltzmann equation for a given reduced electric field E/N. When the Boltzmann equation is solved, chemical kinetic equations are also simultaneously solved to determine essential excited species for the oxygen plasma, while vibrationally excited populations are solved for the nitrogen plasma, since the EEDF should be self-consistently found with the densities of collision counterparts of electrons. Next, the electron mean energy U and entropy S are calculated with the self-consistent EEDF obtained, where the entropy is calculated with the Gibbs’s formula. Then, the “statistical” electron temperature Test is calculated as Test=[∂S/∂U]−1. The difference between Test and the electron kinetic temperature Tekin is discussed, which is defined as [2/(3k)] times of the mean electron energy U=⟨ϵ⟩, as well as the temperature given as a slope of the EEDF for each value of E/N from the viewpoint of statistical physics as well as of elementary processes in the oxygen or nitrogen plasma.

To study the effect of negative ions on the electron energy distribution function (EEDF) of plasma, the electron energies of pure argon and mixed gas (Ar + O 2 ) plasmas were compared based on their EEDFs. An electric probe was used to measure EEDFs together with other plasma parameters such as electron temperature ( T e ), electron density ( n e ), ion density ( n i ), negative ion density ( N - ), plasma potential ( Φ p ), and floating potential ( Φ f ). Negative ion plasma was generated by the discharge of Ar and O 2 gas in a cubical chamber (24 × 24 × 24 cm 3 ) with a direct-current (DC) hot-filament source under the following conditions: working pressure of ~ 2 × 10 −4  Torr, bias voltage ( V b ) of ~ 90 V, n i in the range of 10 9 –10 10  cm −3 , and T e in the range of 1–2 eV. Both the EEDF and the T e values decreased, and the n e / n i decreased to O 2 flow, while the N - / n i ratio showed an opposite tendency. Considering the thermal properties of the Ar + O 2 mixed plasma, the relation between electron temperature, plasma, and floating potential due to the negative ions, α = e Φ p - Φ f / K B T e , did not remain constant; it slowly increased up to 2 sccm and then rapidly increased from 2 to 5 sccm.

Carbon nitride materials have received much attention due to their excellent tribological, mechanical and optical properties. It was found that these qualities depend on the N/C ratio; therefore, the possibility to control it in situ in the sputtered film is of high importance. The plasma-electron spectroscopy method based on the Penning ionization process analysis is developed here to control this ratio in CNx films produced by plasma-sputtering in a pulsed-periodic regime of glow discharge. The electron energy distribution function is determined by the means of a single Langmuir probe placed in the center of the discharge tube. The mixture N2:CH4:He was used in the process of sputtering. The applied concentrations of CH4 varied in the range of 2–8%, and He concentration was 80–90%. The gas pressure in the discharge tube used for sputtering varied between 1 and 10 Torr, and the current was between 10 and 50 mA. It was shown that the proposed method enables the extraction of information on the composition of the surface layer of the investigated film and the development of an on-line inspection, without extracting the film from the sputtering chamber.

The full data set of the NEMO-3 experiment has been used to measure the half-life of the two-neutrino double beta decay of \\[^{100}\\]Mo to the ground state of \\[^{100}\\]Ru, \\[T_{1/2} = \\left[ 6.81 \\pm 0.01\\,\\left( \\text{ stat }\\right) ^{+0.38}_{-0.40}\\,\\left( \\text{ syst }\\right) \\right] \\times 10^{18}\\] year. The two-electron energy sum, single electron energy spectra and distribution of the angle between the electrons are presented with an unprecedented statistics of \\[5\\times 10^5\\] events and a signal-to-background ratio of \\[\\sim \\] 80. Clear evidence for the Single State Dominance model is found for this nuclear transition. Limits on Majoron emitting neutrinoless double beta decay modes with spectral indices of \\[\\mathrm{n}=2,3,7\\], as well as constraints on Lorentz invariance violation and on the bosonic neutrino contribution to the two-neutrino double beta decay mode are obtained.

The evolution of non-equilibrium plasma channel created in xenon by powerful KrF-femtosecond laser pulse is studied. It is demonstrated that such a plasma channel can be used as a waveguide for both transportation and amplification of the microwave radiation. The specific features of such a plasma waveguide are studied on the basis of the self-consistent solution of the kinetic Boltzmann equation for the electron energy distribution function in different spatial points of the gas media and the wave equation in slow-varying amplitude approximation for the microwave radiation guided and amplified in the channel.

The positive column of a gas discharge in helium is investigated for high-modulation-depth discharge current without stepwise ionization. The electron energy distribution function for different discharge current oscillation phases, the electron concentration, and the longitudinal electric field strength are measured in helium gas-discharge plasma. The electric field modulation effect and the change of the electron energy distribution function over the period at frequencies less than the reciprocal ambipolar diffusion time are detected.

We report a statistical result of electrons inside the loss cone with energies of 67 eV–88 keV using electron measurements obtained in situ by the Arase satellite in the inner magnetosphere around the magnetic equator for 60 months. Loss cone electrons are found with a high occurrence probability from the nightside to the dawnside at approximately L = 6. For 641 eV–88 keV electrons, the high‐occurrence region shifts toward later magnetic local times (MLTs) with increasing loss cone electron energy. The spatial distribution of the occurrence probability around MLT = 22–3 at L = 5–6 is consistent with the calculated average resonance energy distribution of whistler mode chorus waves near the magnetic equator. These results suggest that pitch angle scattering driven by chorus waves plays the main role in electron precipitation in this region. Plain Language Summary Energetic electrons originating from the magnetosphere precipitate and transport energy into the upper atmosphere, modifying ionospheric conditions and affecting the magnetosphere‐ionosphere coupling system. Pitch angle scattering caused by wave‐particle interactions in the magnetosphere plays a significant role in generating electrons inside the loss cone, namely, precipitating electrons. However, owing to the few direct observations of loss cone electrons near the magnetic equator, the contribution of wave‐particle interactions to electron precipitation remains an unsolved problem. Recently, energetic electron analyzers with high angular resolutions onboard the Arase satellite have enabled in situ observations of loss cone electron fluxes in the inner magnetosphere. In this study, we conducted a statistical survey of loss cone electrons using these in situ electron measurements in the inner magnetosphere. We discovered that the spatial distribution of precipitating electrons with a high occurrence frequency overlaps with the region where whistler mode chorus waves are detected in the night and early morning sectors. The distribution of the average resonance energies of chorus waves can explain the peak distribution of the precipitating electron energy. These results suggest that chorus waves strongly contribute to electron precipitation with energies of hundreds of eV to tens of keV in this region. Key Points The low‐ and medium‐energy electrons inside the loss cone observed in situ in the inner magnetosphere were statistically investigated The distribution of loss cone electrons coincides with those where chorus waves are observed in the night and early morning sectors The local time dependence of the peak energy of loss cone electrons can be explained by the resonance energy of chorus waves

Experiments were conducted in deuterium plasma in the TJ-II stellarator by means of swept Langmuir probes mounted on reciprocating probes manipulators. The results were processed using the four-parameter fit, as well as the triple-probe and the first-derivative probe techniques. The parameters determined were the floating potential, the ion saturation current density, the electron temperature and density, and the plasma potential. The results were obtained for two plasma heating techniques – electron cyclotron resonance heating (ECRH) and neutral beam injection (NBI) heating. In the case of ECRH, employing the first-derivative probe technique resulted in finding that the electron-energy distribution function (EEDF) was not Maxwellian, but rather a bi-Maxwellian one with thermal (14-25 eV) and cold (4-5 eV) electrons. In comparison, during NBI heating we found a Maxwellian EEDF with the electron temperature being around 5 eV and slightly increasing in the confined plasma, but always remaining below 15 eV. We present a detailed analysis and discussion of the data for the plasma parameters as acquired by different techniques of using the reciprocating probe manipulator.

In recent years, studies on magnetospheric plasmas have increased drastically. Different theoretical models are proposed to match the data observed from various space missions. Still, no sufficient experimental setup is there to replicate the formation like a double layer in these kinds of plasma. In this study, we have made an experimental setup that nearly replicates the magnetospheric plasma environment. We have placed a stainless steel (SS) plate inside our plasma chamber. The argon plasma is produced in the hot cathode discharge method at comparatively high pressure. Then a positive bias is applied to the SS plate with and without attaching a permanent magnet. This positively biased SS plate creates a fireball and firerod-like structures in the absence and presence of the magnet, respectively. This scenario is analogous to the Earth’s magnetospheric plasma and the SS plate represents the pole of the Earth. In this plasma, we have studied the axial variation of ion density ( n i ), electron temperature ( T e ), electron energy distribution function (EEDF), and the plasma potential for both cases. Lastly, we have discussed the nature of the plasma potential variation with a theoretical model.

Thermodynamics of a magnetically expanding plasma (magnetic nozzle (MN)) has been investigated considering the existence of confined electrons bouncing back and forth inside a potential well formed by a combination of external magnetic field and self-generating ambipolar electrostatic potential. The properties of confined electrons are distinguished from that of the adiabatically expanding electrons with γe 5/3 by the separate measurement of each species using a double-sided planar Langmuir probe. Relationship between the electron pressure versus electron density averaged over electron energy probability functions (eepfs) clearly reveals that the confined electrons in MN have a nearly isothermal characteristic. Existence of isothermally behaving confined electrons together with adiabatically expanding electrons separates the MN system into two regions with different thermodynamic properties; one is a nearly adiabatic region located near the nozzle throat and the other is nearly isothermal region located far from the nozzle. A transition of electron thermodynamic property along a distance from the nozzle throat can be explained with conservation of magnetic moment of electrons bounced back by ambipolar electrostatic potential. Coexistence of the nearly adiabatic electrons with Maxwellian eepf and the nearly isothermal electrons with high energy-depleted eepf makes the overall eepf shape low energy-populated eepf, indicating a need for careful analysis on the measured eepfs near the nozzle throat. In spite of significant contribution of confined electrons to eepf and overall electron thermodynamics, it is found that the confined electrons behaving isothermally do not contribute to the generation of ambipolar electrostatic potential which is important for ion acceleration in MN. The present study suggests that ion acceleration should not be directly inferred from the value of polytropic exponent γe because thermodynamic property of a MN is influenced by isothermally behaving confined electrons as well as adiabatically expanding electrons.