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Articoli di riviste sul tema "Electrons"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 28 giugno 2025

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Wang, Xiaoping, Shusai Zheng, Zhen Li, Shaoming Pan, Weibo Fan, Daomin Min, and Shengtao Li. "Radiation electron trajectory modulated DC surface flashover of polyimide in vacuum." Journal of Physics D: Applied Physics 55, no. 20 (February 17, 2022): 205201. http://dx.doi.org/10.1088/1361-6463/ac4cf8.

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Abstract Improving surface flashover voltage on vacuum-dielectric interface irradiated by electrons is a long-standing challenge for developing high-voltage and high-power spacecraft technology. The basic issue is understanding the role of radiation electrons in the process of surface flashover. In this paper, a ‘three-segment’ curve concerning the surface flashover properties under electron irradiation is discovered experimentally. As the gap distance of electrodes increase, the surface flashover voltage of polyimide during electron irradiation presents a trend of firstly increasing, then decreasing, and finally stabilizing. According to the simulation of the trajectory distribution for kinetic electrons, this trend is found to correspond with three typical stages respectively. In stage A, the kinetic electrons are completely deflected and the varying electrode parameters mainly affect the electric field distribution. In stage B, the kinetic electrons can irradiate the part of polyimide. The promoting effect of those electrons on flashover process enhance with the enlargement of the irradiated region. In stage C, trajectories are no longer seriously deflected and the role of kinetic electrons do not vary with electrode parameters. Combining with the results above, a model with combined effects of both kinetic and deposited electrons on surface flashover in vacuum is thus proposed, base on which the guidance for the methods of improving surface flashover voltage during electron irradiation is provided.

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Suzuki, Kosuke, Ayumu Terasaka, Tomoya Abe, and Hiroshi Sakurai. "Modification of Electronic Structures with Lithium Intercalation in Li_xMn₂O₄ (x = 0 and 1) Studied by CRYSTAL14 Calculation Code." Key Engineering Materials 790 (November 2018): 15–19. http://dx.doi.org/10.4028/www.scientific.net/kem.790.15.

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In this study, we calculate electronic structures for Mn2O4 and LiMn2O4 by using CRYSTAL14 ab-initio calculation code in order to understand electrode reaction mechanism of LixMn2O4 by lithiation/delithiation. Mulliken population analysis for all electrons show that the redox orbitals with lithiation and delithiation is O 2p orbitals. However, difference charge densities between majority and minority electrons indicate the change of distribution in Mn 3d orbitals by lithiation. This modification of distribution in Mn 3d orbitals suggests the change of electron configuration because the number of electrons at Mn atom is almost constant in Mulliken population analysis for all electrons. As a result, this modification of distribution in Mn 3d orbitals improves electron conductivity of this material.

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Schultheiss, Katrin, Joachim Zach, Bjoern Gamm, Manuel Dries, Nicole Frindt, Rasmus R. Schröder, and Dagmar Gerthsen. "New Electrostatic Phase Plate for Phase-Contrast Transmission Electron Microscopy and Its Application for Wave-Function Reconstruction." Microscopy and Microanalysis 16, no. 6 (October 15, 2010): 785–94. http://dx.doi.org/10.1017/s1431927610093803.

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AbstractA promising novel type of electrostatic phase plate for transmission electron microscopy (TEM) is presented. The phase plate consists of a single microcoaxial cable-like rod with its electrode exposed to the undiffracted electrons. The emerging field is used to shift the phase of the undiffracted electrons with respect to diffracted electrons. The design overcomes the drawback of the spatial frequency-blocking ring electrode of the Boersch phase plate. First, experimental phase-contrast images are presented for PbSe and Pt nanoparticles with clearly varying phase contrast, which depends on the applied voltage and resulting phase shift of the unscattered electrons. With the new phase-plate design, we show for the first time the reconstruction of an object wave function based on a series of only three experimental phase-contrast TEM images obtained with an electrostatic phase plate.

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Troyon, Michel, and He Ning Lei. "Electron Trajectories Calculations of an Energy - Filtering Field-Emission Gun." Proceedings, annual meeting, Electron Microscopy Society of America 48, no. 1 (August 12, 1990): 192–93. http://dx.doi.org/10.1017/s0424820100179713.

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In many cases, the contribution of beam energy spread to the limitation of the performances of an electron microscope is strong. In the case of the field emission gun (FEG) , Troyon has experimentally shown it is possible to reduce considerably the energy spread by energy filtering at the gun level. The system developed consists basically of a magnetic FEG with a retarding electrode working as the retarding electrode of an energy filter. The principle is recalled in Fig. 1 and the cross section of the accelerator is given in Fig. 2. In this paper, the results of electron trajectories calculations inside the energy filtering field emission gun (EFFEG) are given.Fig. 3 shows that electrons of same energy, but entering the retarding field with different angles, can have exit angles very different. Due to the work function of approximately 4.5 eV the electrons, for an extracting potential Vo = 2 kV, enter in the field of the retarding electrode with an energy smaller than 2 keV. In Fig. 3 trajectories are computed for an electron of 1996 eV. Electrons passing by the nodal points have the same entering and exit angles. Trajectory 1 in Fig. 3 corresponds to an entering radius re = 17.5 μm and an entering semi angle αe = 1.2 mrad. For these re and αe values, at Vr =6 V, the exit semi angle αs = αe . Fig. 3 shows that an electron entering parallely to the axis, even very close to the axis (re = 10 μm) has a larger exit angle than electrons passing by the nodal points.

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Joens, Steve. "Hitachi S-4700 ExB Filter Design and Applications." Microscopy and Microanalysis 7, S2 (August 2001): 878–79. http://dx.doi.org/10.1017/s1431927600030464.

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Electron beam - specimen interactions and SEM signals have been well understood and documented for many years. These interactions result in a variety of electron signals including the most common, secondary and backscattered electron. Each electron signal produces unique characteristic information about the sample surface, subsurface, and elemental composition. Important information can be gained by controlling and filtering electron signals collected by the electron detector system.The S-4700 Cold Field Emission SEM incorporates a set of electrodes and plates positioned in the objective lens upper pole piece in close proximity to the upper secondary detector (figure 1). When a positive voltage is applied to the electrode plates, a high yield of secondary and backscattered electrons spiral up the column of the objective lens. The backscattered electrons are filtered with the ExB producing a SE rich signal. The information from this type of signal provides absolute detail from the sample surface, but can be prone to charging with some highly nonconductive samples. Figure 2a shows the effect of charging while observing uncoated Teflon ™. The image becomes distorted with bright intermittent horizontal lines. Surface detail is enhanced due to the high contribution of SEs from the sample surface.When the electrode voltage is set negative, through the instrument GUI, the low energy secondary electrons are repelled providing a signal rich in backscattered electrons. The information from this type of signal provides compositional information and inherently reduces charging. The uncoated Teflon ™ sample in figure 2b shows all charging affects have been eliminated.

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Dedulewich, S., Z. Kancleris, A. Matulis, and Yu Pozhela. "Electron-electron scattering in hot electrons." Semiconductor Science and Technology 7, no. 3B (March 1, 1992): B322—B323. http://dx.doi.org/10.1088/0268-1242/7/3b/081.

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Mitrokhovich, M. F., V. T. Kupryashkin, and L. P. Sidorenko. "Correlation of the Auger electrons direction of movement with the internal electron conversion direction of movement." Nuclear Physics and Atomic Energy 14, no. 2 (June 30, 2013): 129–34. https://doi.org/10.15407/jnpae2013.02.129.

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By registering coincidences of γ-quanta with electrons and with low (about zero) energy electrons, the spatial correlation of the direction of emitted Auger-electrons and electron of internal conversion was investigated in the 152Eu decay. Auger-electrons were registered by е0-electrons of the secondary electron emission (γеICе0-coincidences). It was established that Auger-electrons of M-series, as well as electrons "shake-off" at β-decay and internal conversion, are strongly correlated at the direction of movement with the direction of movement of basic particle (β-particle, conversion electron), moving together mainly in the forward hemisphere. The intensity of correlated М-Auger radiation in range of energy 1000 - 1700 eV is equal to intensity of correlated radiation "shake-off" electron from internal conversion in this range. The assumption, that the presence of spatial correlating Auger-electron and conversion electron caused by current components of electron-electron interaction of particles in the final state is made.

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Golden, Joel, Matthew D. Yates, Michelle Halsted, and Leonard Tender. "Application of electrochemical surface plasmon resonance (ESPR) to the study of electroactive microbial biofilms." Physical Chemistry Chemical Physics 20, no. 40 (2018): 25648–56. http://dx.doi.org/10.1039/c8cp03898h.

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Results reveal that for an electrode-grown Geobacter sulfurreducens biofilm, as much as 70% of cytochrome hemes residing within hundreds of nanometers from the electrode surface store electrons even as extracellular electron transport is occurring across the biofilm/electrode interface.

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Toth, M., and M. R. Phillips. "Space Charge Artifacts in ESEM Images: Shadowing and Contrast Reversal." Microscopy and Microanalysis 6, S2 (August 2000): 774–75. http://dx.doi.org/10.1017/s1431927600036369.

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The environmental scanning electron microscope (ESEM) employs a series of pressure limiting apertures and a differential pumping system to allow for electron imaging at specimen chamber pressures of up to 50 torr. Images rich in secondary electron (SE) contrast can be obtained using the gaseous secondary electron detector (GSED) or ion current (Iion) signals. The GSED and Iion signals are amplified in a gas cascade. SEs emitted from a sample are accelerated through the gas in the specimen chamber by an electric field, EGSED, produced by a positively biased electrode located in the chamber, above the specimen. The accelerated SEs give rise to a cascade ionization process that can amplify the SE signal by up to three orders of magnitude. Electrons produced in the cascade are rapidly swept to the biased electrode and are efficiently removed from the gas. Positive ions produced in the cascade drift away from the electrode with a velocity that is at least three orders of magnitude lower than that of the electrons.

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Nur-E-Habiba, Rokon Uddin, Kalle Salminen, Veikko Sariola, and Sakari Kulmala. "Carbon Particle-Doped Polymer Layers on Metals as Chemically and Mechanically Resistant Composite Electrodes for Hot Electron Electrochemistry." Journal of Electrochemical Science and Technology 13, no. 1 (February 28, 2022): 100–111. http://dx.doi.org/10.33961/jecst.2021.00640.

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This paper presents a simple and inexpensive method to fabricate chemically and mechanically resistant hot electron-emitting composite electrodes on reusable substrates. In this study, the hot electron emitting composite electrodes were manufactured by doping a polymer, nylon 6,6, with few different brands of carbon particles (graphite, carbon black) and by coating metal substrates with the aforementioned composite ink layers with different carbon-polymer mass fractions. The optimal mass fractions in these composite layers allowed to fabricate composite electrodes that can inject hot electrons into aqueous electrolyte solutions and clearly generate hot electron-induced electrochemiluminescence (HECL). An aromatic terbium (III) chelate was used as a probe that is known not to be excited on the basis of traditional electrochemistry but to be efficiently electrically excited in the presence of hydrated electrons and during injection of hot electrons into aqueous solution. Thus, the presence of hot, pre-hydrated or hydrated electrons at the close vicinity of the composite electrode surface were monitored by HECL. The study shows that the extreme pH conditions could not damage the present composite electrodes. These low-cost, simplified and robust composite electrodes thus demonstrate that they can be used in HECL bioaffinity assays and other applications of hot electron electrochemistry.

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Liu, Qingyu, Qinhe Zhang, Min Zhang, and Fazhan Yang. "Study on the Discharge Characteristics of Single-Pulse Discharge in Micro-EDM." Micromachines 11, no. 1 (January 1, 2020): 55. http://dx.doi.org/10.3390/mi11010055.

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To further study the discharge characteristics and machining mechanism of micro-electrical discharge machining (micro-EDM), the variation trends of the discharge energy and discharge crater size with actual discharge duration are discussed based on single-pulse experiments. The polarity effect of micro-EDM was analyzed according to the motion characteristics of electrons and ions in the discharge plasma channel. The results show that the discharge current and voltage of micro-EDM were independent of the discharge width and open-circuit voltage. The energy utilization rate of the short-pulse discharge was relatively high, and the energy utilization rate decreased gradually as the discharge duration increased. Even if the mass of the positive ion was much larger than that of the electron, the kinetic energy of the positive ion was still less than that of the electron when bombarding the surface of the electrode. The acceleration and speed of electrons were very high, and the number of times that electrons bombarded the surface of positive electrode was more than 600 times that of positive ions bombarding the surface of the negative electrode during the same time.

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ZHANG, C. "EFFECT OF INELASTIC SCATTERING OF HOT ELECTRONS ON THERMIONIC COOLING IN A SINGLE-BARRIER STRUCTURE." International Journal of Modern Physics B 14, no. 14 (June 10, 2000): 1451–57. http://dx.doi.org/10.1142/s0217979200001503.

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One of the important problems in thermionics using layered structures is the inelastic scattering of hot electrons in the electrodes and in the barrier region. Scattering in these systems is mainly via the electron–phonon interaction, or indirectly via the electron–electron interaction. In semiconductor heterostructures at room temperature, the LO-phonon plays a crucial role in thermalising electrons. In this work we study the effect of electron–phonon scattering on thermionic cooling in a single-barrier structure. Because of the asymmetry of the barrier under a bias, a larger fraction of the total energy loss will be dissipated in the hot electrode. As a result, we find that the theoretical thermal efficiency can increase due to limited electron–phonon scattering.

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Si, Putu Gede Gunawan Tista, Siswanto Eko, Nur Sasongko Mega, and Nyoman Gede Wardana I. "Development of voltage generation using bamboo-based activated carbon with water electrolyte in three types of electrodes." Eastern-European Journal of Enterprise Technologies 6, no. 6(108) (December 31, 2020): 71–79. https://doi.org/10.15587/1729-4061.2020.213099.

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The use of a battery as a power supply for small electronic devices, such as camera, laptop, and handphone, with a wireless sensory network, is currently being developed. Besides, climate change keeps on worsening because of the use of fossil fuel emitting carbon and increase in global warming. However, due to climate change, many have sought alternatives to reduce carbon emissions. Therefore, the use of environmentally friendly material such as bamboo is essential. The generation of electrical energy in this study used bamboo-based activated carbon as an electrode, which was put between counter electrodes. The electrical energy was generated from a system consisting of a counter electrode – electrode – counter electrode. Three types of counter electrode tested were copper, aluminum, and aluminum foil. An electrolyte was injected between the electrode and counter electrode before being heated. The electrolyte tested was distilled water. The electrostatic force was generated by water electrolyte ions toward the poles of functional groups, the electrical charge of the pores, and electron mobility in the counter electrode; so, the release of electrons occurred. The result shows that the highest thermal sensitivity of the electrical voltage (dV/dT) was generated by aluminum 64.043 mV/°C, followed by aluminum foil 63.578 mV/°C and copper 6.136 mV/°C. This is because the electron mobility in aluminum was higher while the phosphorus content of the aluminum foil tends to attract electrons, inhibiting the release of electrons. The electrical voltage generated was effective when above the temperature of ∆T=45 °C. This is because the hydrogen bond of the water molecule was weakened, causing the ions to become easily attracted to the activated carbon surface inducing more release of electrons

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McMorran, Benjamin J., Peter Ercius, Tyler R. Harvey, Martin Linck, Colin Ophus, and Jordan Pierce. "Electron Microscopy with Structured Electrons." Microscopy and Microanalysis 23, S1 (July 2017): 448–49. http://dx.doi.org/10.1017/s1431927617002926.

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Stetsun, A. I. "The Density of MoSi2 Electron States for the Amorphous Film." Фізика і хімія твердого тіла 17, no. 3 (September 15, 2016): 372–74. http://dx.doi.org/10.15330/pcss.17.3.372-374.

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The density of MoSi2 electron states for the amorphous film has been calculated. An electron states at the top of valence band for this material are provided d electrons of molybdenum, p electrons of silicon and p electrons of molybdenum. d electrons of molybdenum are significant especially for physical properties of MoSi2.

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AMEMIYA, H., B. M. ANNARATONE, and J. E. ALLEN. "The double sheath associated with electron emission into a plasma containing negative ions." Journal of Plasma Physics 60, no. 1 (August 1998): 81–93. http://dx.doi.org/10.1017/s0022377898006837.

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The double sheath formed by thermal electrons and negative ions in a plasma and electrons emitted from an electrode is investigated. The ion energy at the sheath edge and the electric field at the electrode surface are calculated for several values of the ratio of negative-ion density to electron density. The maximum beam density above which a virtual cathode appears is given. The relation to the Langmuir limit is shown. The numerical results for the electric potential, the electric field and the space charge density are presented. The floating potential is calculated from the current balance of all components.

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Haddad, Raoudha, Jean-Gabriel Mattei, Jessica Thery, and Aurélien Auger. "Novel ferrocene-anchored ZnO nanoparticle/carbon nanotube assembly for glucose oxidase wiring: application to a glucose/air fuel cell." Nanoscale 7, no. 24 (2015): 10641–47. http://dx.doi.org/10.1039/c5nr00497g.

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Glucose oxidase is immobilized on a ZnO-Fc nanoparticle modified electrode. The new architecture of ZnO supported electron mediators to shuttle electrons from the redox centre of the enzyme to the surface of the working electrode can bring about successful glucose oxidation.

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Seol, Youbin, Hong Young Chang, Seung Kyu Ahn, and Shin Jae You. "Effect of mixing CF₄ with O₂ on electron characteristics of capacitively coupled plasma." Physics of Plasmas 30, no. 1 (January 2023): 013503. http://dx.doi.org/10.1063/5.0120850.

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Effect of mixing CF4 with O2 on electron parameters in capacitively coupled RF plasma was studied. Adding CF4 gas to fixed O2 flow, electron energy probability functions were measured by a Langmuir probe method. As the CF4 gas was added, the decrease in the probability of low energy electrons was observed. The proportion of low energy electrons decreased gradually as the CF4 gas ratio increased, respectively. From electron energy probability functions, electron densities and electron temperatures were calculated. As the CF4 gas ratio increased, electron density decreased and electron temperature increased. Collision cross sections of low energy electrons can explain electron parameter behaviors. By the strong electron attachment of fluorine species which were generated from CF4, low energy electrons depleted by attachment, and the overall electron temperature increased. However, as the elastic collision cross section of CF4 is not different from that of O2, the heating mechanism and physics of high energy electrons did not change.

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VALERI, SERGIO, and ALESSANDRO di BONA. "MODULATED ELECTRON EMISSION BY SCATTERING-INTERFERENCE OF PRIMARY ELECTRONS." Surface Review and Letters 04, no. 01 (February 1997): 141–60. http://dx.doi.org/10.1142/s0218625x9700016x.

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We review the effects of scattering-interference of the primary, exciting beam on the electron emission from ordered atomic arrays. The yield of elastically and inelastically backscattered electrons, Auger electrons and secondary electrons shows a marked dependence on the incidence angle of primary electrons. Both the similarity and the relative importance of processes experienced by incident and excident electrons are discussed. We also present recent studies of electron focusing and defocusing along atomic chains. The interplay between these two processes determines the in-depth profile of the primary electron intensity anisotropy. Finally, the potential for surface-structural studies and limits for quantitative analysis are discussed, in comparison with the Auger electron diffraction (AED) and photoelectron diffraction (PD) techniques.

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Kumar, Amit, Krishna Katuri, Piet Lens, and Dónal Leech. "Does bioelectrochemical cell configuration and anode potential affect biofilm response?" Biochemical Society Transactions 40, no. 6 (November 21, 2012): 1308–14. http://dx.doi.org/10.1042/bst20120130.

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Electrochemical gradients are the backbone of basic cellular functions, including chemo-osmotic transport and ATP synthesis. Microbial growth, terminal respiratory proteins and external electron transfer are major pathways competing for electrons. In BESs (bioelectrochemical systems), such as MFCs (microbial fuel cells), the electron flow can be via soluble inorganic/organic molecules or to a solid surface. The flow of electrons towards a solid surface can be via outer-membrane cytochromes or electron-shuttle molecules, mediated by conductive protein nanowires or extracellular matrices. In MECs (microbial electrolysis cells), the anode potential can vary over a wide range, which alters the thermodynamic energy available for bacteria capable of donating electrons to the electrode [termed EAB (electroactive bacteria)]. Thus the anode potential is an important electrochemical parameter determining the growth, electron distribution/transfer and electrical activity of films of these bacteria on electrodes. Different optimal applied potentials to anodes have been suggested in the literature, for selection for microbial growth, diversity and performance in biofilms on electrodes. In the present paper, we review the effects of anode potentials on electron-transfer properties of such biofilms, and report on the effect that electrochemical cell configuration may have on performance.

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Hauga, E. "Electron-electron bremsstrahlung for bound target electrons." European Physical Journal D 49, no. 2 (August 26, 2008): 193–99. http://dx.doi.org/10.1140/epjd/e2008-00156-5.

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Kirdyashev, K. P. "Anomalous transport of electrons in an electric discharge with transverse magnetic field." Journal of Physics: Conference Series 2056, no. 1 (October 1, 2021): 012050. http://dx.doi.org/10.1088/1742-6596/2056/1/012050.

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Abstract The experimental data showing the relationship of excitation of microwave oscillations with abnormally transport of electrons across the magnetic field in turbulent plasma are presented. The mechanism of the formation of the discharge current due to scattering of drift electrons in the near-electrode layers of the electric discharges on microwave oscillations has been substantiated. The conditions for the manifestation of the turbulent mechanism of anomalous electron transport through the magnetic barrier at the boundary of the toroidal electric discharge have been studied most fully. The mobility of electrons across a magnetic field is one of the main parameters of electric discharges that use crossed electric and magnetic fields for technological purposes.

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Al-Owais, A., and I. S. El-Hallag. "Investigation of The Electrode Pathway of Quinoline Azo Dye Compound via Convolutive Voltammetry and Digital Simulation." Journal of New Materials for Electrochemical Systems 19, no. 2 (June 30, 2016): 091–95. http://dx.doi.org/10.14447/jnmes.v19i2.335.

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The electrochemical behavior and the electrode reaction of quinolone azo dye compound was investigated using convolutive cyclic voltammetry at mercury electrode in 50% (v/v) ethanolic Britton-Robinson solutions of pH 2.5 – 12.0. Four electrons slow reduction wave was consumed in acidic and alkaline solutions corresponding to the reduction of the more easily N = N center. A second more cathodic irreversible , pH – dependent, 2-electron wave represents the reduction of quinolone ring. Cyclic voltammetry and convolution transforms were used to determine the kinetic parameters of the electroactive species.The extracted electrochemical parameters were confirmed via digital simulation.Controlled potential coulometry technique was used for calculation the overall number of electrons involved in electrode reaction.

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Nishide, Hiroyuki, Kenichiroh Koshika, and Kenichi Oyaizu. "Environmentally benign batteries based on organic radical polymers." Pure and Applied Chemistry 81, no. 11 (October 15, 2009): 1961–70. http://dx.doi.org/10.1351/pac-con-08-12-03.

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A radical polymer is an aliphatic organic polymer bearing densely populated unpaired electrons in the pendant robust radical groups per repeating unit. These radicals’ unpaired electrons are characterized by very fast electron-transfer reactivity, allowing reversible charging as the electrode-active materials for secondary batteries. Organic-based radical batteries have several advantages over conventional batteries, such as increased safety, adaptability to wet fabrication processes, easy disposability, and capability of fabrication from less-limited resources, which are described along the fashion of green chemistry.

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Rigler, Mark, and William Longo. "High Voltage Scanning Electron Microscopy Theory and Applications." Microscopy Today 2, no. 5 (August 1994): 12–13. http://dx.doi.org/10.1017/s1551929500066256.

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A variety of energy emissions occur as a result of primary beam interaction with the specimen surface. Secondary electrons, x-rays, visible photons, near IR photons, and Auger electrons are emitted during inelastic scattering of electrons. Backscattered electrons (BSE) are emitted during elastic scattering of primary electrons. Backscattered electrons are those electrons which pass through the electron cloud of an atom and change direction without much energy loss. BSEs may diffuse into the sample or may escape from the sample surface. In practice, the primary electron beam penetrates deeply into low Z (atomic number) materials and produces few BSEs while high Z materials retard primary beam penetration and emit large numbers of BSEs. According to Murata et al., the higher the atomic number, the smaller the mean free path between electron scattering events (i.e. 528 Å for Al vs. 50 Å for Au at 30 KeV) and the higher the probability of scattering.

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Son, Dong Hee. "(Invited) Upconverted Hot Electrons from Semiconductor Nanocrystals for Enhancing Photocatalysis." ECS Meeting Abstracts MA2024-01, no. 35 (August 9, 2024): 1984. http://dx.doi.org/10.1149/ma2024-01351984mtgabs.

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The exciton-to-hot electron upconversion phenomenon in Mn-doped semiconductor quantum dots (QDs) produces highly energetic hot electrons. These electrons have an average energy just a fraction of 1 eV below the vacuum level, with a subpopulation of hot electrons existing above the vacuum level. This hot electron upconversion process is similar to photon upconversion in lanthanide-doped nanoparticles. However, the final state here is a highly excited hot electron in the conduction band of the host QDs, not a state emitting higher-energy photons. These upconverted hot electrons can be harnessed to carry out thermodynamically and kinetically challenging reduction reactions, benefiting from their high excess kinetic energy and long-range transfer capability. The presentation will discuss recent demonstrations of the benefits of these upconverted hot electrons in various photocatalytic reduction and redox-neutral reactions. Additionally, the development of new materials for more efficient hot electron upconversion and the potential to broaden the application of these energetic hot electrons beyond photocatalysis will be discussed.

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Shi Han-Xu, Li Xin-Yang, Zhang Yu-Ru, and Wang You-Nian. "Numerical investigation of the secondary electron effect in capacitively coupled plasmas driven by ultra-low frequency/radio frequency sources." Acta Physica Sinica 74, no. 13 (2025): 0. https://doi.org/10.7498/aps.74.20250341.

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In recent years, capacitively coupled plasmas driven by ultra-low frequency source have garnered increasing attention, because they are beneficial for generating ions with high energy and small scattering angle, which aligns well with the current trend in high aspect ratio etching. Since the sheath becomes thicker when a ultra-low frequency source is applied, the secondary electron emission becomes significant. Indeed, these energetic secondary electrons could enhance the ionization process and even influence the discharge mode. In this work, a two-dimensional fluid model is employed to study the influence of secondary electrons on the dual frequency capacitively coupled plasmas under different ultra-low frequency voltages, secondary electron emission coefficients and inter-electrode gaps. The high frequency is fixed at 13.6 MHz, and the ultra-low frequency is fixed at 400 kHz. First, by using the ion energy dependent secondary electron emission coefficient, it is shown that the electron density first decreases and then increases with ultra-low frequency voltage. This is because on one hand, the higher ultra-low frequency voltage leads to thicker sheath, and therefore, the effective discharge volume is compressed. On the other hand, secondary electrons emitted from electrodes could obtain more energy, and thus enhance the ionization process. By comparing with the results obtained with fixed secondary electron emission coefficients, it is found that in the low voltage range, the evolution of the electron density is similar to that with fixed coefficient of 0.1. While, in the high voltage range, the growth of the electron density is even more pronounced than that with fixed coefficient of 0.2, indicating that the enhancement of the secondary electron effect by ultra-low frequency voltage is non-linear. Finally, the impact of discharge gap on the plasma properties has also been discussed. It is shown that with the increase of inter-electrode gap from 2 cm to 4 cm, the maximum ionization rate becomes lower, but the electron density rises significantly, and the plasma radial uniformity is improved. When inter-electrode gap is large, secondary electrons could collide with neutral species fully, and thus their influence on the electron density at high ultra-low frequency voltage is more pronounced. The results obtained in this paper are helpful to understand the influence of ultra-low frequency source on the secondary electron effect, and provide some guidance for the optimization of plasma processing.

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Wayama, Fumiya, Noriyuki Hatsugai, and Yasuaki Okumura. "Bipyridines mediate electron transfer from an electrode to nicotinamide adenine dinucleotide phosphate." PLOS ONE 17, no. 6 (June 16, 2022): e0269693. http://dx.doi.org/10.1371/journal.pone.0269693.

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Biocatalysts are widely used in industry, but few examples of the use of oxidoreductases, in which enzymatic function often requires electrons, have been reported. NADPH is a cofactor that supplies an electron to oxidoreductases, but is consequently inactivated and no longer able to act as an electron donor. NADP+ can not receive electrons from electrodes through straightforward electrochemistry owing to its complicated three-dimensional structure. This study reports that bipyridines effectively mediate electron transfer between an electrode and NADP+, allowing them to serve as electron mediators for NADPH production. Using bipyridines, quinones, and anilines, which have negative oxidation–reduction potentials, an electrochemical investigation was conducted into whether electrons were transferred to NADP+. Only bipyridines with a reduction potential near -1.0 V exhibited electron transfer. Furthermore, the NADPH production level was measured using spectroscopy. NADPH was efficiently produced using bipyridines, such as methyl viologen and ethyl viologen, in which the bipyridyl 1- and 1’-positions bear small substituents. However, methyl viologen caused a dehydrogenation reaction of NADPH, making it unsuitable as an electron mediator for NADPH production. The dehydrogenation reaction did not occur using ethyl viologen. These results indicated that NADP+ can be reduced more effectively using substituents that prevent a dehydrogenation reaction at the bipyridyl 1- and 1’-positions while maintaining the reducing power.

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Xie, Mengjun, Dagang Liu, Huihui Wang, and Laqun Liu. "Study on the Correlation between Magnetic Field Structure and Cold Electron Transport in Negative Hydrogen Ion Sources." Applied Sciences 12, no. 9 (April 19, 2022): 4104. http://dx.doi.org/10.3390/app12094104.

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In most negative hydrogen ion sources, an external magnet is installed near the extraction region to reduce the electron temperature. In this paper, the self-developed CHIPIC code is used to simulate the mechanism of a magnetic filter system, in the expansion region of the negative hydrogen ion source, on “hot” electrons. The reflection and the filtering processes of “hot” electrons are analyzed in depth and the energy distribution of electrons on the extraction surface is calculated. Moreover, the effects of different collision types on the density distribution of “cold” electrons along the X-axis and the spatial distribution of “cold” electrons on the X−Z plane are discussed. The numerical results show that the electron reflection is caused by the magnetic mirror effect. The filtering of “hot” electrons is due to the fact that the magnetic field constrains most of the electrons from reaching the vicinity of the extraction surface, being that collisions cause a decay in electron energy. Excitation collision is the main decay mechanism for electron energy in the chamber. The numerical results help to explain the formation process of “cold” electrons at the extraction surface, thus providing a reference for reducing the loss probability of H−.

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Petrov, G. M., and A. Davidson. "Collisional and transport parameters of Cu in the warm dense matter regime calculated using the average atom model." Plasma Physics and Controlled Fusion 63, no. 12 (November 2, 2021): 125011. http://dx.doi.org/10.1088/1361-6587/ac2e3f.

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Abstract Collisional and transport parameters for Cu are computed using the average atom model. Transition metals such as copper are difficult to model within the framework of the average atom model due to the presence of a narrow band of 3d electrons that mix and hybridize with the broad 4s band of nearly-free electrons. With electron temperature increasing, the 3d electrons play a key role in the thermodynamics and transport properties of Cu (Lin et al 2008 Phys. Rev. B 77 075133), as well as the stability of the lattice (Loboda et al 2011 High Energy Density Phys. 7 361). In this work, the average atom model was used to track the average energy of the 3d band and its evolution with electron temperature. At room temperature, its center is at ∼6 electron volts (eV), a few electron-volts below the Fermi energy, and with electron temperature increasing it sinks relative to it. At electron temperature of about 8 eV the 3d electrons leave the conduction band and become bound. A long-standing problem related to the average ion charge observed by conduction band electrons is addressed and successfully resolved. A work-around has been found that predicts the correct average ion charge, Z ˉ , by formally introducing a third group of electrons: quasi-bound electrons. Benchmarking with published data is made that shows good agreement.

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LOTOV, K. V. "Optimum angle for side injection of electrons into linear plasma wakefields." Journal of Plasma Physics 78, no. 4 (April 12, 2012): 455–59. http://dx.doi.org/10.1017/s0022377812000335.

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AbstractA unified model of electron penetration into linear plasma wakefields is formulated and studied. The optimum angle for side injection of electrons is found. At smaller angles, all electrons are reflected radially. At larger angles, electrons enter the wakefield with superfluous transverse momentum that is unfavorable for trapping. Separation of incident electrons into penetrated and reflected fractions occurs in the outer region of the wakefield at some ‘reflection’ radius that depends on electron energy.

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Keszei, Ernö, and Jean-Paul Jay-Gerin. "On the role of the parent cation in the dynamics of formation of laser-induced hydrated electrons." Canadian Journal of Chemistry 70, no. 1 (January 1, 1992): 21–23. http://dx.doi.org/10.1139/v92-004.

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A short account is given of the continuum and molecular descriptions of the formation of hydrated electrons. Starting with a scheme of hydration dynamics of laser-induced electrons that accounts for the formation of hydrated electrons without invoking the "direct" ionization of water, a new model explaining the dynamics of electron hydration in terms of a molecular description is proposed. According to this model, the parent cation plays an active role in the trapping of electrons, deepening electron traps that preexist in the liquid before excitation. Consequences of this description to the transient absorption spectra are briefly discussed. Keywords: laser-induced electron – cation pairs, hydrated electron formation, liquid water.

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MISHRA, M. K., and A. PHUKAN. "Electron heating in a multi-dipole plasma by electrostatic plugging." Journal of Plasma Physics 79, no. 2 (September 12, 2012): 153–61. http://dx.doi.org/10.1017/s0022377812000815.

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AbstractThe effect of the electrostatic confinement potential on electron number densities and electron temperatures under bi-Maxwellian approximation for electron distribution function has been studied in an electrostatically plugged multi-dipole argon plasma system. Electrostatic plugging is implemented by biasing the electrically isolated multi-dipole magnetic cage. Experimental results show that the density ratio (N) and temperature ratio (T) of the two electron groups can be controlled by changing the voltage applied to the magnetic cage. Out of the two groups of electrons, one group has the cold electrons, which are plasma electrons produced by the ionization process, and the other group has the hot primary electrons.

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Gilet, N., P. Henri, G. Wattieaux, N. Traoré, A. I. Eriksson, X. Vallières, J. Moré, et al. "Observations of a mix of cold and warm electrons by RPC-MIP at 67P/Churyumov-Gerasimenko." Astronomy & Astrophysics 640 (August 2020): A110. http://dx.doi.org/10.1051/0004-6361/201937056.

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Context. The Mutual Impedance Probe (MIP) of the Rosetta Plasma Consortium (RPC) onboard the Rosetta orbiter which was in operation for more than two years, between August 2014 and September 2016 to monitor the electron density in the cometary ionosphere of 67P/Churyumov-Gerasimenko. Based on the resonance principle of the plasma eigenmodes, recent models of the mutual impedance experiment have shown that in a two-electron temperature plasma, such an instrument is able to separate the two isotropic electron populations and retrieve their properties. Aims. The goal of this paper is to identify and characterize regions of the cometary ionized environment filled with a mix of cold and warm electron populations, which was observed by Rosetta during the cometary operation phase. Methods. To reach this goal, this study identifies and investigates the in situ mutual impedance spectra dataset of the RPC-MIP instrument that contains the characteristics of a mix of cold and warm electrons, with a special focus on instrumental signatures typical of large cold-to-total electron density ratio (from 60 to 90%), that is, regions strongly dominated by the cold electron component. Results. We show from the observational signatures that the mix of cold and warm cometary electrons strongly depends on the cometary latitude. Indeed, in the southern hemisphere of 67P, where the neutral outgassing activity was higher than in northern hemisphere during post-perihelion, the cold electrons were more abundant, confirming the role of electron-neutral collisions in the cooling of cometary electrons. We also show that the cold electrons are mainly observed outside the nominal electron-neutral collision-dominated region (exobase), where electrons are expected to have cooled down. This which indicates that the cold electrons have been transported outward. Finally, RPC-MIP detected cold electrons far from the perihelion, where the neutral outgassing activity is lower, in regions where no electron exobase was expected to have formed. This suggests that the cometary neutrals provide a more frequent or efficient cooling of the electrons than expected for a radially expanding ionosphere.

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Mitrokhovich, M. F. "Energy and correlation properties of "shake-off" electrons in β-decay". Nuclear Physics and Atomic Energy 11, № 2 (30 червня 2010): 125–35. https://doi.org/10.15407/jnpae2010.02.125.

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Measurements of energy spectrum of "shake-off" electrons in the decay of 152Eu and their correlations relatively to outgoing direction with a momentum of β-particle are conducted. The measurements are performed in the range of 150 - 2000 eV on the installation of coincidences of γ-quanta and β-particles with low energy electrons, including е0-electrons of the secondary electron emission (γβе0-coincidences). Registration of "shake-off" electrons was implemented on е0-electrons, created by them. Under the obtained data 70% of "shake-off" electrons in the measured part of the spectrum is arranged up to 500 eV, and "shake-off" electrons are heavily correlated relatively to outgoing direction with a β-particle, herein their correlation with the energy of "shake-off" electron is increasing, qualitatively subjected to ∼ Е1/2 relation.

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Kumar, Anil, David Becker, Amitava Adhikary, and Michael D. Sevilla. "Reaction of Electrons with DNA: Radiation Damage to Radiosensitization." International Journal of Molecular Sciences 20, no. 16 (August 16, 2019): 3998. http://dx.doi.org/10.3390/ijms20163998.

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This review article provides a concise overview of electron involvement in DNA radiation damage. The review begins with the various states of radiation-produced electrons: Secondary electrons (SE), low energy electrons (LEE), electrons at near zero kinetic energy in water (quasi-free electrons, (e−qf)) electrons in the process of solvation in water (presolvated electrons, e−pre), and fully solvated electrons (e−aq). A current summary of the structure of e−aq, and its reactions with DNA-model systems is presented. Theoretical works on reduction potentials of DNA-bases were found to be in agreement with experiments. This review points out the proposed role of LEE-induced frank DNA-strand breaks in ion-beam irradiated DNA. The final section presents radiation-produced electron-mediated site-specific formation of oxidative neutral aminyl radicals from azidonucleosides and the evidence of radiosensitization provided by these aminyl radicals in azidonucleoside-incorporated breast cancer cells.

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Jung, Hyuck, Duck-Jin Lee, Hyun-Tae Chun, Nam-Je Koh, Young Rae Cho, and Dong-Gu Lee. "Carbon Nanotube Field Emitters for Display Applications Using Screen Printing." Materials Science Forum 475-479 (January 2005): 1889–92. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.1889.

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In this study, a 10"-sized panel with novel tetrode structure was tried to prevent broadening of electrons emitted from CNTs. The structure of the novel tetrode is composed of CNT emitters on a cathode electrode, a gate electrode, an extracting electrode coated on the top of a hopping electron spacer (HES), and an anode. HES contains funnel-shaped holes whose inner surfaces are coated with MgO. Electrons extracted through the gate are collected inside the funnel-shaped holes and hop along the hole surface to the top extracting electrode. The effects of HES on emission characteristics of field emission display (FED) were investigated. An active ozone treatment for the complete removal of residues of organic binders in the emitter devices was applied to the FED panel as a post-treatment

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KI, DAE-HAN, and YOUNG-DAE JUNG. "Density and temperature effects on a surface electron-acoustic wave in a semi-bounded dusty plasma of two-temperature electrons." Journal of Plasma Physics 73, no. 4 (August 2007): 433–38. http://dx.doi.org/10.1017/s0022377806004685.

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AbstractThe effects of density and temperature on a surface electron-acoustic plasma wave are investigated in a semi-bounded dusty plasma of two-temperature electrons. The dispersion relation of the surface electron-acoustic plasma wave is obtained by the plasma dielectric function with the specular reflection boundary condition. The phase velocity is found to be decreased when increasing the ratio of the temperature of hot electrons to that of cold electrons for large wave numbers. It is also found that the phase velocity increases with an increase in the ratio of the density of hot electrons to that of cold electrons and that the phase velocity of the surface electron-acoustic wave increases with an increase in the density of the dust grains.

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Mesyats, G. A., A. G. Reutova, K. A. Sharypov, V. G. Shpak, S. A. Shunailov, and M. I. Yalandin. "On the observed energy of runaway electron beams in air." Laser and Particle Beams 29, no. 4 (December 2011): 425–35. http://dx.doi.org/10.1017/s0263034611000541.

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AbstractExperiments with an air electrode gap have been performed where the current/charge of a picosecond beam of runaway electrons was measured over a wide range (up to four orders of magnitude) downstream of the absorbing foil filters. Measurements and calculations have made it possible to refer the beam current to the rise time of the accelerating voltage pulse to within picoseconds. It has been shown that, in contrast to a widespread belief, the runaway electron energies achieved are no greater than those corresponding to the mode of free acceleration of electrons in a nonstationary, highly nonuniform electric field induced by the cathode voltage. The experimental data agree with predictions of a numerical model that describes free acceleration of particles. It has been confirmed that the magnitude of the critical electric field that is necessary for electrons to go into the mode of continuous acceleration of electrons in atmospheric air corresponds to classical notions.

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HOLLETT, JOSHUA W., and RAYMOND A. POIRIER. "AN INTERESTING RELATIONSHIP BETWEEN INTERELECTRONIC DISTANCE AND THE CORRESPONDING COULOMB INTEGRAL." Journal of Theoretical and Computational Chemistry 06, no. 01 (March 2007): 13–22. http://dx.doi.org/10.1142/s0219633607002782.

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A simple expression for the distance between two electrons, (δr12)ab, has been defined from one-electron expectation values. This value is calculated for triplet and singlet systems of two electrons, and closed-shell molecules of up to 58 electrons. When (δr12)ab is compared to the corresponding coulomb integral, Jab, an interesting relationship is observed. The relationship is followed extremely closely by all pairs of electrons, except for some deviations involving delocalized core–core electron pairs.

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MISHRA, M. K., A. PHUKAN, and M. CHAKRABORTY. "Effect of discharge voltage on bi-Maxwellian electrons in the diffusion plasma region of a double plasma device." Journal of Plasma Physics 79, no. 5 (July 3, 2013): 913–20. http://dx.doi.org/10.1017/s0022377813000597.

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AbstractThe effect of discharge voltage on bi-Maxwellian electrons in the diffusion region of a double plasma device has been studied. The increase in discharge voltage enhances the flux of ionizing electrons to the diffusion region separated by a mesh grid. This energetic electron flux in turn affects other important parameters such as density, electron temperature, plasma potential and floating potential in the diffusion region. Furthermore, the dependence of density and temperature of both ionizing and plasma electrons on discharge voltage is investigated. The electron energy probability function obtained from probe data also indicates the bi-Maxwellian nature of electrons.

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Zhou, M., T. Li, X. Deng, S. Huang, and H. Li. "Comparisons of electron acceleration efficiency among different structures during magnetic reconnection: a Cluster multicase study." Annales Geophysicae 33, no. 12 (December 1, 2015): 1469–78. http://dx.doi.org/10.5194/angeo-33-1469-2015.

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Abstract. Magnetic reconnection has long been believed to be an efficient engine for energetic electrons production. Four different structures have been proposed for electrons being energized: flux pileup region, density cavity located around the separatrix, magnetic island and thin current sheet. In this paper, we compare the electron acceleration efficiency among these structures based on 12 magnetotail reconnection events observed by the Cluster spacecraft in 2001–2006. We used the flux ratio between the energetic electrons (> 50 keV) and lower energy electrons (< 26 keV) to quantify the electron acceleration efficiency. We do not find any specific sequence in which electrons are accelerated within these structures, though the flux pileup region, magnetic island and thin current sheet have higher probabilities to reach the maximum efficiency among the four structures than the density cavity. However, the most efficient electron energization usually occurs outside these structures. We suggest that other structures may also play important roles in energizing electrons. Our results could provide important constraints for the further modeling of electron acceleration during magnetic reconnection.

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Singh, S. V., and G. S. Lakhina. "Electron acoustic solitary waves with non-thermal distribution of electrons." Nonlinear Processes in Geophysics 11, no. 2 (April 14, 2004): 275–79. http://dx.doi.org/10.5194/npg-11-275-2004.

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Abstract. Electron-acoustic solitary waves are studied in an unmagnetized plasma consisting of non-thermally distributed electrons, fluid cold electrons and ions. The Sagdeev pseudo-potential technique is used to carry out the analysis. The presence of non-thermal electrons modifies the parametric region where electron acoustic solitons can exist. For parameters representative of auroral zone field lines, the electron acoustic solitons do not exist when either α > 0.225 or Tc/Th > 0.142, where α is the fractional non-thermal electron density, and Tc (Th) represents the temperature of cold (hot) electrons. Further, for these parameters, the simple model predicts negatively charged potential structures. Inclusion of an electron beam in the model may provide the positive potential solitary structures.

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Ram, Abhay K., Kyriakos Hizanidis, and Richard J. Temkin. "Current drive by high intensity, pulsed, electron cyclotron wave packets." EPJ Web of Conferences 203 (2019): 01009. http://dx.doi.org/10.1051/epjconf/201920301009.

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The nonlinear interaction of electrons with a high intensity, spatially localized, Gaussian, electro-magnetic wave packet, or beam, in the electron cyclotron range of frequencies is described by the relativistic Lorentz equation. There are two distinct sets of electrons that result from wave-particle interactions. One set of electrons is reﬂected by the ponderomotive force due to the spatial variation of the wave packet. The second set of electrons are energetic enough to traverse across the wave packet. Both sets of electrons can exchange energy and momentum with the wave packet. The trapping of electrons in plane waves, which are constituents of the Gaussian beam, leads to dynamics that is distinctly diﬀerent from quasilinear modeling of wave-particle interactions. This paper illustrates the changes that occur in the electron motion as a result of the nonlinear interaction. The dynamical diﬀerences between electrons interacting with a wave packet composed of ordinary electromagnetic waves and electrons interacting with a wave packet composed of extraordinary waves are exempliﬁed.

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Abdelrazak Mansour Ali, Radwa Abdelrazak Ali, and Ahmed Abdelrazak Ali. "A study discovered the coherent wave function of electrons and the stability when observed." World Journal of Advanced Research and Reviews 17, no. 3 (March 30, 2023): 876–82. http://dx.doi.org/10.30574/wjarr.2023.17.3.0485.

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The wave phase is the origin of creation and precedes the particulate (molecular) phase. The wave and particle are not two figures of the same thing, rather they are heterogeneous and different from each other due to the different sources of each of them. The particulate phase is just generated by impinging of the wave on its target of spatial forces (Higgs field), and the wave phase is considered the extra dimensions or the extended fuzzy end of the particle. Because electrons are forced to move in synchrony, they can produce heat and light. The light would be reflected from the electron forming many synchronized shadows for the same electron at different places that could be misinterpreted by both the instrumental detectors and the person analyzing the results of observations. Therefore, the electron cannot exist in different places, rather the shadows of the same electron give false observational results that produced the false analytic conclusion of “probability and randomness” and thus the term “superposition” is not scientifically consistent or coherent– The energy and momentum of electrons influence their motion through a material, which, in turn, determines its electrical and optical properties. – Using laser pulses, physicists have been able to generate hot electrons that travel faster than the speed of light. Regarding the electrons in the famous double-slit experiment, they are considered accelerated electrons, so their speed is faster than the speed of light. Because the light emitted from electrons and the light of the electron detector (ICCD camera) are electromagnetic waves, the speed of light emitted from electrons is faster than that of the detector. Consequently, the electron detector (ICCD camera) could detect the particle phase of electrons but couldn’t detect or capture the wave phase of electrons, because electromagnetic waves are harder to get a handle on. The result is the failure of observing and detecting the wave phase of electrons. Therefore, the wave function does not collapse.

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Abdelrazak, Mansour Ali, Abdelrazak Ali Radwa, and Abdelrazak Ali Ahmed. "A study discovered the coherent wave function of electrons and the stability when observed." World Journal of Advanced Research and Reviews 17, no. 3 (March 30, 2023): 876–82. https://doi.org/10.5281/zenodo.8136014.

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Hamabata, Hiromitsu, and Tomikazu Namikawa. "Instability of low-frequency waves in a cold plasma mixed with hot electrons." Journal of Plasma Physics 33, no. 3 (June 1985): 437–41. http://dx.doi.org/10.1017/s0022377800002609.

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The instability of low-frequency waves in a cold plasma mixed with hot electrons is investigated using the first-order CGL equations for electrons. It is assumed that in an equilibrium state the electrons consist of two components, cold electrons and hot electrons with bi-Maxwellians. It is shown that low-frequency waves with right-hand polarization can be generated by the hot electron temperature anisotropy and the existence of cold electrons.

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Wei, Y. Y., S. Y. Huang, K. Jiang, Z. G. Yuan, S. B. Xu, J. Zhang, Q. Y. Xiong, et al. "Direct Evidence of Electron Acceleration at the Dipolarization Front." Astrophysical Journal 950, no. 2 (June 1, 2023): 112. http://dx.doi.org/10.3847/1538-4357/acd1dd.

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Abstract The dramatic changes in the magnetic field at the dipolarization front (DF) provide a suitable environment for electron acceleration, which usually can cause the flux enhancement of energetic electrons behind the front. However, it is unknown whether energetic electrons observed at the DF are energized locally, and which mechanism accelerates the electrons at the DF is unclear. Our study performs a direct quantitative analysis to reveal the acceleration process of energetic electrons at the DF using the high-time-resolution data from NASA's Magnetospheric Multiscale mission. The fluxes of energetic electrons at 90° are enhanced at the front. Under adiabatic conditions, our quantitative analysis indicates that these electrons at the front could be locally accelerated to over 100 keV by betatron acceleration. Eventually, the electron temperature anisotropy formed via the betatron mechanism could provide the free energy to excite whistler waves at the DF. Our quantitative study provides, for the first time, strong direct evidence for the local electron acceleration at the DF.

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Liu, Terry Z., Vassilis Angelopoulos, and San Lu. "Relativistic electrons generated at Earth’s quasi-parallel bow shock." Science Advances 5, no. 7 (July 2019): eaaw1368. http://dx.doi.org/10.1126/sciadv.aaw1368.

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Plasma shocks are the primary means of accelerating electrons in planetary and astrophysical settings throughout the universe. Which category of shocks, quasi-perpendicular or quasi-parallel, accelerates electrons more efficiently is debated. Although quasi-perpendicular shocks are thought to be more efficient electron accelerators, relativistic electron energies recently observed at quasi-parallel shocks exceed theoretical expectations. Using in situ observations at Earth’s bow shock, we show that such relativistic electrons are generated by the interaction between the quasi-parallel shock and a related nonlinear structure, a foreshock transient, through two betatron accelerations. Our observations show that foreshock transients, overlooked previously, can increase electron acceleration efficiency at a quasi-parallel shock by an order of magnitude. Thus, quasi-parallel shocks could be more important in generating relativistic electrons, such as cosmic ray electrons, than previously thought.

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Engelhardt, I. A. D., A. I. Eriksson, E. Vigren, X. Valliéres, M. Rubin, N. Gilet, and P. Henri. "Cold electrons at comet 67P/Churyumov-Gerasimenko." Astronomy & Astrophysics 616 (August 2018): A51. http://dx.doi.org/10.1051/0004-6361/201833251.

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Context. The electron temperature of the plasma is one important aspect of the environment. Electrons created by photoionization or impact ionization of atmospheric gas have energies ~10 eV. In an active comet coma, the gas density is high enough for rapid cooling of the electron gas to the neutral gas temperature (a few hundred kelvin). How cooling evolves in less active comets has not been studied before. Aims. We aim to investigate how electron cooling varied as comet 67P/Churyumov-Gerasimenko changed its activity by three orders of magnitude during the Rosetta mission. Methods. We used in situ data from the Rosetta plasma and neutral gas sensors. By combining Langmuir probe bias voltage sweeps and mutual impedance probe measurements, we determined at which time cold electrons formed at least 25% of the total electron density. We compared the results to what is expected from simple models of electron cooling, using the observed neutral gas density as input. Results. We demonstrate that the slope of the Langmuir probe sweep can be used as a proxy for the presence of cold electrons. We show statistics of cold electron observations over the two-year mission period. We find cold electrons at lower activity than expected by a simple model based on free radial expansion and continuous loss of electron energy. Cold electrons are seen mainly when the gas density indicates that an exobase may have formed. Conclusions. Collisional cooling of electrons following a radial outward path is not sufficient to explain the observations. We suggest that the ambipolar electric field keeps electrons in the inner coma for a much longer time, giving them time to dissipate energy by collisions with the neutrals. We conclude that better models are required to describe the plasma environment of comets. They need to include at least two populations of electrons and the ambipolar field.

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