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The conversion of methane into transportable and storable materials is crucial in the petrochemical sector. In this study, a specially constructed AC‐driven dielectric barrier discharge (DBD) that has charge injector pyramids on one of the electrodes and runs at ambient temperature and pressure was used to evaluate noncatalytic methane conversion. The obtained result was compared with the traditional flat electrode DBD. It was discovered that the product selectivity in direct nonoxidative methane conversion depended on the discharge conditions. Pyramid electrode plasma sources convert methane up to 50% $ \% $ more than flat electrode plasma due to the appearance of more microdischarges. Pyramid electrode plasma generally has a greater production efficiency than flat electrode plasma, while requiring more operational power. The turnkey solutions offered by the sustainable methane coupling method discussed here may be advantageous for the long‐term small‐scale ethylene exploration scenario. [ABSTRACT FROM AUTHOR]

Recently, a bouncing-like mechanism for electron multiplication inside long nano-ruptures during the early stages of nanosecond discharge in liquid water has been proposed in (Bonaventura 2021 Plasma Sources Sci. Technol. 30 065023). This mechanism leads to the formation of electron avalanches within nano-ruptures caused by strong electrostrictive forces. The avalanche propagation is a self-sustaining process: the electrons emitted from the water surface to the cavity support the propagation of the avalanche and the avalanche itself is a source of the parent electrons impinging on the surface of the nano-rupture and causing secondary emission. We analyze the process of the electron secondary emission directly from the simulation results of the electron avalanche propagation. This allow us to perform an in situ study of the secondary emission and related physical processes. We present the results of an extensive parametric study performed using the state-of-the-art simulation toolkit Geant4-DNA for modeling electron-liquid water interactions. It is shown that the typical lifetime of an electron in an avalanche is about 0.1 to 0.2 picoseconds and that the electron experiences about 4 bounces before ending up in liquid water. In addition, it is shown that the secondary electrons are formed in a layer adjacent to the nano-rupture surface that is only a few nanometres thin. The secondary electron velocity distribution at the moment of the electron birth, the velocity space of electrons (re-)emitted from the water, and the velocity space of electrons at the moment of their impact to the cavity surface are analyzed in detail. Electron bouncing and secondary electron generation efficiency are quantified using the secondary emission coefficient, the secondary emission efficiency, and the effective energy consumed to produce new electrons. [ABSTRACT FROM AUTHOR]

The purpose of this work is to study the dielectric charging of polymer fibers with the electron plasma charging effects accompanied by the emergence of waves propagating along the polymer fiber surface. Monitoring of the charge propagation along the single fiber has been performed using dielectric polyhydroxybutyrate (PHB) fibers obtained by the electrospinning (ESP) method under the electron beam inside the scanning electron microscope chamber. The mechanical effect of the electron beam on the polymer fibers has been detected in a time-lapse mode. The influence of the polymer surface irregularities and mechanical defects on the fiber charging has been demonstrated. Plasma mechanism is typical not only for electrophysical phenomena but also for the control of mechanical movement of the fibers by the electron beam and the charge propagation during electron-beam-induced melting and in the presence of hydrodynamic polymer flows. It is assumed that the mechanical effect in the methods using an electron beam (and plasma on the dielectric surface) as an impact source can be determined by the following factors: pressure of the electron beam and the electric field, contribution of the secondary emission, thermal/thermomechanical factors, and dynamic balance or competition between all the forces affecting the sample (electron-beam pressure, gravity pressure, recoil pressure during evaporation, vapor pressure/surface tension, and so on). In addition to purely scientific interest, the above phenomena are also of significant applied interest since the influence of the polymer fiber charging on the separation procedure of aerosols in nonwoven filters is well known, and hence, charging of such polymer fibers is important for some energy storage devices. [ABSTRACT FROM AUTHOR]

In the process of integrating large-scale wind farms into the power system, the harmonic interaction among wind farms causes potential safe and stable operation threats to the power grid. To effectively control the harmonics of the wind power grid-connected system, quantitative analysis of the harmonic interaction is very necessary and meaningful. Therefore, this paper firstly explains the harmonic interaction among wind farms from the perspective of the primary and secondary emission. We use the concept of harmonic impedance to analyze the mechanism of harmonic interaction and proposed a calculation method for quantitative analysis of the harmonic interaction. Using the calculation method, the influence caused by the wind farm self-impedance, the contact impedance, and Static Var Generator to the harmonic interaction are quantitatively analyzed. Finally, taking multiple wind farms in actual operation as a case, the effectiveness of the method is verified by time domain simulation.

Quantum-mechanical transitions arising under optical excitation of globular photonic crystals are analyzed. Possible cases of electron—phonon and electron—photon—phonon coupling initiated by laser pumping are discussed. Spectral characteristics of acoustic waves emitted during electron—phonon transitions in synthetic opal are calculated. The maximum frequency of arising electromagnetic radiation is estimated. The crucial role of free electrons localized within globules in excitation of radiative processes in the crystal is accented. [ABSTRACT FROM AUTHOR]

Measurement of electron energy spectra of dielectrics is a challenge due to charging issues. This article presents experimental results of electron energy spectra of dielectric materials under electron irradiation obtained by transforming the charging process into a spectroscopic tool. The technique was verified on conductive materials in a previous paper. This method is based on capturing the charging transient of the secondary electron emission current. Dielectric materials are irradiated with a single train of pulses of monoenergetic electrons. The evolution of the number of emitted electrons as a function of time is measured. The rate of this evolution coupled to the arising potential on the surface of the material conveys the energy at which the secondary electrons are emitted. The total incident dose used in this method is about 10 pC/mm2, in contrast to the high doses required when other common methods are utilized. The use of low doses ensures a minimal distortion of the pristine state of the dielectric material by avoiding radiation damage, deep charging, defects, aging and other electron induced phenomena in the insulator. This method was applied to obtain the secondary electron energy spectra of the Kapton, Teflon, and Ultem polymers.

The cathode in the magnetron should have good secondary emission property and a certain thermionic property. In this article, ZrH2 was added as an activator to obtain rare earth-doped tungsten matrix impregnated cathode to improve the emission property. Cathodes with ZrH2 (Y15-411-Zr cathode) or without ZrH2 (Y15-411 cathode) were prepared by a spray drying method combined with high-temperature sintering in dry hydrogen atmosphere. The emission properties and emission mechanism have been studied. The results showed that thermionic emission performance and secondary emission performance of Y15-411-Zr cathode are 3.4 times and 1.2 times higher than those of Y15-411 cathode, respectively. With the addition of ZrH2, yttrium was produced during activating process, which contributed to the better emission properties of Y15-411-Zr cathode. Furthermore, the work function of barium and oxygen adsorbed on yttrium oxide and yttrium surface was calculated using the first principle. The results showed that the lowest work function of Ba-O absorbed on Y2O3 and Y is 1.9 and 1.6 eV, respectively. [ABSTRACT FROM AUTHOR]

The test results of the prototype of the secondary-emission probe operating in the mode of self-oscillatory sweep intended for diagnosing nonequilibrium plasma in the presence of epithermal group of electrons are given. Earlier, the method of self-oscillatory probe was tested using an aluminum water-cooled contact surface with formation of a nanoscale thick high-emission oxide coating. The structure of the described probe is peculiar owing to application of refractory tantalum, which is capable of working in the mode of radiation cooling, which simplifies the structure and increases the reliability of the probe. It is shown that, owing to secondary-emission characteristics, oxide-coated tantalum allows under plasma loading obtaining a pronounced N-type current–voltage characteristic with a large excess in the electron-emission current component against the ion saturation current and satisfies all requirements for realization of the method of self-oscillatory probe. [ABSTRACT FROM AUTHOR]

A method of ion saturation current measurement in a nonequilibrium plasma by a self-oscillating voltage sweep on the probe is described. The generation of voltage pulses is possible if a high secondary electron emission from the probe surface is ensured, significantly exceeding unity at a moderate negative potential. The theoretical basis of the self-oscillating probe method has been considered, which made it possible to describe the ways for controlling the repetition rate and pulse amplitude and the effect of plasma parameters on the shape of current and voltage signals. It is shown that the features of the phase trajectory of the signal from the probe on the (U, I) plane allow one to determine the reference points of instantaneous probe characteristic, in particular, the ion saturation current. The results of experiments on testing the self-oscillating probe technique, which were carried out using the PR-2 plasma-beam facility, are presented. [ABSTRACT FROM AUTHOR]

In this paper, we have investigated the effect of secondary electron emission on the propagation characteristics of linear dust acoustic waves in dusty plasmas consisting of suprathermal inertialess primary electrons, secondary electrons, Boltzmann distributed ions, and negatively charged inertial dust grains. The suprathermal electrons are assumed to follow kappa velocity distribution. We have derived the linear dispersion relation and shown that real and imaginary frequencies of the waves are influenced by the strength of secondary electron emission as well as suprathermal electron population. [ABSTRACT FROM AUTHOR]

This paper presents a study of the multipactor effect in a partially dielectric-loaded rectangular waveguide. To obtain the simulations presented in this paper, a detailed analysis of the dynamics of the electron inside this waveguide has been performed, taking into account the radio frequency electromagnetic fields propagating in the waveguide and the dc electric field that appears because of the charging of the dielectric layer. This electrostatic field is obtained by computing the electric potential produced by an arbitrary charge distribution on the dielectric layer in a dielectric-loaded waveguide. The electron trajectory is then found by numerically solving the equations of motion. The results obtained show that multipactor discharges do turn off by themselves under certain circumstances when they occur in such dielectric-loaded waveguide. [ABSTRACT FROM AUTHOR]

• Supraharmonic emission differs among single-phase and three-phase installations due to conductor crosstalk. • Four parameters are shown to impact, i.e., the cable used in an installation, length of the conductor and conductor impedance, load impedance of the devices connected in all phases and transformer impedance. • A sensitivity analysis among the influencing parameters is carried out where the type of cable and the length of cable show the highest sensitivity • Induced primary and secondary emission becomes more significant for longer cables for frequencies greater than 100 kHz The induced primary emission leads to changes in the primary emission of a device and the induced secondary emission leads to changes in the propagation of supraharmonics in the adjacent phase due to the connection of single-phase loads spread over three phases in an installation. The induced primary emission and induced secondary emission are shown to give a significant contribution to the total emission measured at a given point in an installation. The induction of the emission is caused by the inductive and capacitive coupling among the conductors within the cables. This paper presents an analysis of four parameters that impact the magnitude of the induced emissions. Simulations carried out in COMSOL, show that the type of cable used impacts the induced emission and studies show that shielded cable with a stranded conductor with the shield grounded will lead to a reduction in the induced emissions. Among the other parameters, i.e., the load and transformer impedance and the length of the cable, the length of the cable is dominating in deciding the magnitude of the induced emissions. Analysis is carried out using Monte Carlo simulation and varying parameters stochastically. For all investigated parameters there is a strong frequency dependency. The stochastic variation of the load impedance in one phase causes a variation of 5% whereas the change in length of the cable leads to a maximum 40% variation in the considered frequency range for induced primary emission. Measurement results are presented to validate the results. [ABSTRACT FROM AUTHOR]

Resistive Plate Chambers (RPCs) are essential active media of large-scale experiments as part of the muon systems and (semi-)digital hadron calorimeters. Among the several outstanding issues associated with the RPCs, the loss of efficiency for the detection of particles when subjected to high particle fluxes, and the limitations associated with the common RPC gases can be listed. In order to address the latter issue, we developed novel RPC designs with special anode plates coated with high secondary electron emission yield materials such as Al 2 O 3 and TiO 2. The proof of principle was obtained for various designs and is in progress for the rest. The idea was initiated following the achievements on the development of the novel 1-glass RPCs. Here we report on the construction of various different RPC designs, and their performance measurements in laboratory tests and with particle beams; and discuss the future test plans. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A simple spectrometer design for pulsed laser ablation plumes. • Distinguish particles with the same mass-to-charge ratio. • Simple design, with no high voltage pulsing. • Reconfigurable to adjust uncertainty and operating energy range. • Prototype demonstration. Abstract A mass spectrometer has been designed to distinguish ions of different mass but identical mass to charge ratio. Separation of mass from charge is based upon secondary particle emission when each ion impacts the detector. The yield of secondary particles is a function of kinetic energy rather than energy-per-charge. Combined with an electrostatic energy gate and time-of-flight, the mass can be determined from kinetic energy, energy-per-charge, and mass-per-charge. The design is of moderate precision but simpler than available alternatives – particles need not be extracted from the vacuum chamber for sizing nor the detector kept at cryogenic temperatures. The prototype is demonstrated on an aluminum ablation plume and an ionic liquid ion source. [ABSTRACT FROM AUTHOR]

A compact introduction to the history and the canonical equations of electron emission is given for thermal emission (Richardson), field emission (Fowler–Nordheim), photoemission (Fowler–DuBridge), and secondary emission (Baroody), as well as the space-charge-limited flow (Child–Langmuir law). A general equation is derived and related to the canonical equations. Processes that affect emission, such as coatings, shielding, excitation and transport, space charge, emittance, and material properties, are considered. Requirements imposed by beam evolution are discussed. [ABSTRACT FROM AUTHOR]

Hundreds of concurrent collisions per bunch crossing are expected at future hadron colliders. Precision timing calorimetry has been advocated as a way to mitigate the pileup effects and, thanks to their excellent time resolution, microchannel plates (MCPs) are good candidate detectors for this goal. We report on the response of MCPs, used as secondary emission detectors, to single relativistic particles and to electromagnetic showers. Several prototypes, with different geometries and characteristics, were exposed to particle beams at the INFN-LNF Beam Test Facility and at CERN. Their time resolution and efficiency are measured for single particles and as a function of the multiplicity of particles. Efficiencies between 50% and 90% to single relativistic particles are reached, and up to 100% in presence of a large number of particles. Time resolutions between 20 ps and 30 ps are obtained. [ABSTRACT FROM AUTHOR]

Influence of electric field of charged spacecraft on secondary emission currents on the spacecraft surface is analyzed in terms of computation of secondary electron trajectories. Dependencies of the recollected electrons number on the electric field intensity at various distances from the emission point for standard secondary electron spectra are calculated. Criteria of the secondary electron emission suppression by the surface electric field which is applied for spacecraft charging modeling using the COULOMB-2 code are proposed. Modeling of the emitted electron trajectories in the electric field of the charged spacecraft having complex surface configuration enables to compute correction factors added to electric current balance equations (electron recollection). [ABSTRACT FROM PUBLISHER]

A size-resolved, one-dimensional resuspension scheme for soil particles from the ground surface is proposed to evaluate the concentration of radioactivity in the atmosphere due to the secondary emission of radioactive material. The particle size distributions of radioactive particles at a sampling point were measured and compared with the results evaluated by the scheme using four different soil textures: sand, loamy sand, sandy loam, and silty loam. For sandy loam and silty loam, the results were in good agreement with the size-resolved atmospheric radioactivity concentrations observed at a school ground in Tsushima District, Namie Town, Fukushima, which was heavily contaminated after the Fukushima Dai-ichi Nuclear Power Plant accident in March 2011. Though various assumptions were incorporated into both the scheme and evaluation conditions, this study shows that the proposed scheme can be applied to evaluate secondary emissions caused by aeolian resuspension of radioactive materials associated with mineral dust particles from the ground surface. The results underscore the importance of taking soil texture into account when evaluating the concentrations of resuspended, size-resolved atmospheric radioactivity. [ABSTRACT FROM AUTHOR]

Abstract The late pulse occurring in photomultiplier tubes (PMTs) is attributed to photoelectron backscattering. The small effective open area of microchannel plates (MCPs) increases the probability of photoelectrons bouncing on the front surface of MCPs and aggravates late pulses. In this work, a three-dimensional MCP-PMT model is developed in CST particle studio, a powerful electromagnetic field simulation program, to evaluate the effects of secondary emission yield (SEY) property of the MCP input facet and electric field on the photoelectron backscattering. Timing properties and the number of collected electrons are extracted without smearing due to electronic noise and finite pulse width. Results predict that the collection efficiency (CE) and the time performance can be improved by coating the MCP Nickel–Chromium input electrode with a high SEY material and operating in a proper photocathode-MCP bias voltage. Highlights • The physical processes leading to an output pulse of the MCP-PMT are analyzed. • The effects of the secondary emission yield (SEY) property of the MCP input facet and the electric field on the photoelectron backscattering are investigated. • Both the timing and the collection efficiency of the later pulses are studied. • Solutions to improve the collection efficiency and the timing performance of the MCP-PMT are discussed. [ABSTRACT FROM AUTHOR]