Electron Speed Research Articles

Bipolar Optical Systems with Plasma Sources Positioned Behind Rear Cathode Face

The paper deals with the one-dimensional model of ion and electron flows, which allows estimating the electron current amplification due to the ion injection from the plasma source positioned behind the rear face of the perforated cathode (the fountain of ions). The case of the self-magnetic field is also considered at relativistic speeds of electrons. The parameter estimation is presented for the cathode heating by ions emitted from the anode and the rear face of the perforated cathode.

Plant-Based Natural Dye-Stimulated Visible-Light Reduction of GO and Physicochemical Factors Influencing the Production of Oxidizing Species by a Synthesized (rGO)/TiO2 Nanocomposite for Environmental Remediation.

Here, we report our findings related to the structural and photocatalytic considerations that influence the speed of electron–hole separation in semiconductor photocatalysis in the presence of reduced graphene oxide. A comparison of the exterior properties required for the degradation of the dye methylene blue and drug amoxicillin (C16H19N3O5S) as a probe by the synthesized photocatalyst reduced graphene oxide (rGO)/TiO2 nanowire with graphene oxide and reduced graphene oxide; TiO2 alone reveals that TiO2 is significantly influenced by three factors: (1) rGO interactions with TiO2 in terms of electron and hole transfer, (2) mode of reduction strategies adopted for reducing graphene oxide, and (3) production of OH• by the catalyst used. This work provides a thorough insight into the smooth, encouraging, and environment-friendly way developed for synthesizing reduced graphene oxide (rGO). The indigo dye-stimulated visible-light reduction methodology not only gives us an easy light-assisted reduction technique but also leads to new ways to get photoactive carbon-based titania semiconductor nanocomposites. Inspired by advances taking place in materials science as well as nanotechnology, we sought to develop improved photocatalytic materials by modifications to anatase TiO2 through which opportunities to improve the performance of photocatalytic pollutant treatment may emerge.

The Balloon-Borne Investigation of Temperature and Speed of Electrons in the Corona (BITSE): Mission Description and Preliminary Results

We report on the Balloon-borne Investigation of Temperature and Speed of Electrons in the corona (BITSE) mission launched recently to observe the solar corona from approx 3 Rs to 15 Rs at four wavelengths (393.5, 405.0, 398.7, and 423.4 nm). The BITSE instrument is an externally occulted single stage coronagraph developed at NASA’s Goddard Space Flight Center in collaboration with the Korea Astronomy and Space Science Institute (KASI). BITSE used a polarization camera that provided polarization and total brightness images of size 1024 times 1024 pixels. The Wallops Arc Second Pointer (WASP) system developed at NASA’s Wallops Flight Facility (WFF) was used for Sun pointing. The coronagraph and WASP were mounted on a gondola provided by WFF and launched from the Fort Sumner, New Mexico station of Columbia Scientific Balloon Facility (CSBF) on September 18, 2019. BITSE obtained 17,060 coronal images at a float altitude of approx mbox{128,000} feet (approx 39 km) over a period of approx 4 hrs. BITSE flight software was based on NASA’s core Flight System, which was designed to help develop flight quality software. We used EVTM (Ethernet Via Telemetry) to download science data during operations; all images were stored on board using flash storage. At the end of the mission, all data were recovered and analyzed. Preliminary analysis shows that BITSE imaged the solar minimum corona with the equatorial streamers on the east and west limbs. The narrow streamers observed by BITSE are in good agreement with the geometric properties obtained by the Solar and Heliospheric Observatory (SOHO) coronagraphs in the overlapping physical domain. In spite of the small signal-to-noise ratio (approx 14) we were able to obtain the temperature and flow speed of the western steamer. In the heliocentric distance range 4 – 7 Rs on the western streamer, we obtained a temperature of approx 1.0pm 0.3 MK and a flow speed of approx 260 km s−1 with a large uncertainty interval.

Interplay of parallel electric field and trapped electrons in kappa-Maxwellian auroral plasma for EMEC instability

In this paper, propagation characteristics of electromagnetic electron cyclotron (EMEC) waves based on kappa-Maxwellian distribution have been investigated to invoke the interplay of the electric field parallel to the Earth’s magnetic field and auroral trapped electrons. The dispersion relation for EMEC waves in kappa-Maxwellian distributed plasma has been derived using the contribution of the parallel electric field and trapped electron speed. Numerical results show that the presence of the electric field has a stimulating effect on growth rate, which is more pronounced at low values of wave number. It is also observed that as the threshold value of trapped electron speed is surpassed, it dominates the effect of the parallel electric field and EMEC instability is enhanced significantly. The electric field acts as another source of free energy, and growth can be obtained even in the absence of trapped electron drift speed and for very small values of temperature anisotropy. Thus the present study reveals the interplay of the parallel electric field and trapped electron speed on the excitation of EMEC waves in the auroral region.

A two-fluid analysis of waves in a warm ion–electron plasma

Following recent work, we discuss waves in a warm ideal two-fluid plasma consisting of electrons and ions starting from a completely general, ideal two-fluid dispersion relation. The plasma is characterized by five variables: the electron and ion magnetizations, the squared electron and ion sound speeds, and a parameter describing the angle between the propagation vector and the magnetic field. The dispersion relation describes six pairs of waves which we label S, A, F, M, O, and X. Varying the angle, it is argued that parallel and perpendicular propagation (with respect to the magnetic field) exhibit unique behavior. This behavior is characterized by the crossing of wave modes which is prohibited at oblique angles. We identify up to six different parameter regimes where a varying number of exact mode crossings in the special parallel or perpendicular orientations can occur. We point out how any ion–electron plasma has a critical magnetization (or electron cyclotron frequency) at which the cutoff ordering changes, leading to different crossing behaviors. These are relevant for exotic plasma conditions found in pulsar and magnetar environments. Our discussion is fully consistent with ideal relativistic MHD and contains light waves. Additionally, by exploiting the general nature of the dispersion relation, phase and group speed diagrams can be computed at arbitrary wavelengths for any parameter regime. Finally, we recover earlier approximate dispersion relations that focus on low-frequency limits and make direct correspondences with some selected kinetic theory results.

Design of a multichannel photonic crystal dielectric laser accelerator

To be useful for most scientific and medical applications, compact particle accelerators will require much higher average current than enabled by current architectures. For this purpose, we propose a photonic crystal architecture for a dielectric laser accelerator, referred to as a multi-input multi-output silicon accelerator (MIMOSA), that enables simultaneous acceleration of multiple electron beams, increasing the total electron throughput by at least 1 order of magnitude. To achieve this, we show that the photonic crystal must support a mode at the Γ point in reciprocal space, with a normalized frequency equal to the normalized speed of the phase-matched electron. We show that the figure of merit of the MIMOSA can be inferred from the eigenmodes of the corresponding infinitely periodic structure, which provides a powerful approach to design such devices. Additionally, we extend the MIMOSA architecture to electron deflectors and other electron manipulation functionalities. These additional functionalities, combined with the increased electron throughput of these devices, permit all-optical on-chip manipulation of electron beams in a fully integrated architecture compatible with current fabrication technologies, which opens the way to unconventional electron beam shaping, imaging, and radiation generation.

Quantum Impedance of Proton and Beta Particle by Employing the DE-Broglie Hypothesis alongside Heisenberg’s Uncertainty Principle

IN this paper, alongside Heisenberg's principle of uncertainty, the De-Broglie wavelength hypothesis was used to conclude at a new understanding of the quantum impedance shown by the proton when interacting with the material. It also extracted the quantum impedance, speed, and frequency of electron (a beta particle with energy below 1MeV). This assumed that the electrons and protons have the same wavelength when interacting with the material at a high- voltage vacuum power supply. These formulas can be considered as one of the important applications in nanotechnology that can be used in the field of radiotherapy. The findings obtained concerning beta particle velocity showed that they are compatible with their established formulations, but with a new method. Furthermore, the Beta particle frequency formula may be viewed as a new version. The use of uncertainty in determining the location and momentum of the proton and the beta particle has also been found to have a significant impact in achieving their quantum impedances. Besides that, the quantum impedance of beta particle was obtained according to the principle of conductivity. The results showed the relevance of equation 8 when evaluating the impedance of the proton. It is attributed to the inclusion of the Mp / Me ratio, in addition to the similarity of the remaining variables with the content of the beta particle's quantum impedance formula. The Die-Broglie wavelength was determined, as opposed to the usual. Results showed that a linear relationship between the velocity of the beta ray and its frequency with the power supply.

Carbon aerogel/SnO2 as an advanced anode for sodium-ion batteries

As the anode of sodium-ion batteries (SIBs), SnO2 has been attracted considerable attention due to its high theoretical specific capacity. However, these shortcomings of SnO2 anode seriously restrict its practical use for high-performance SIBs due to its poor conductivity, volume expansion and agglomeration of the active material during cycling. In this paper, carbon aerogel (CA) is a three-dimensional porous material with glucose as carbon source and freeze-dried hydrogel method is used to retain three-dimensional network structure by calcination. SnO2 is prepared by hydrothermal method with nanoparticles and distributed on the CA homogeneously to prepare CA/SnO2. The CA/SnO2 is prepared for SIB, in which CA can alleviate the problem of volume expansion and improve poor conductivity of SnO2 as a good carrier. Moreover, the porous structure of CA is beneficial to increase the contact between the electrolyte and the electrode, and accelerates the transmission speed of ions and electrons. Nano-sized SnO2 also contributes to cycle stability. The CA/SnO2 exhibits superior electrochemical performance and maintains a reversible discharge specific capacity of 235[Formula: see text]mAh[Formula: see text]g[Formula: see text] at a current density of 50[Formula: see text]mA[Formula: see text]g[Formula: see text] after 100 cycles.

Synoptic Measurements of Electron Temperature and Speed in the Solar Corona with Next Generation White-Light Coronagraph

Current white-light coronagraphs measure polarized brightness (pB) of the solar corona using a single bandpass filter to measure the density of electrons. However, future coronagraphs can be modified to take pB images through four bandpass filters to measure density, temperature and speed of electrons. In this article, we use a spherical three dimensional coronal model of the Bastille Day coronal mass ejection to synthetically measure pB through four bandpass filters along lines of sight originating from two observers located diametrically in front (1 AU, 0, 0) and behind (-1 AU, 0, 0) the plane of the sky on the xy-ecliptic plane. The lines of sight pass through 81 positions on a straight line parallel to the solar north–south z-direction in the yz-plane and this line intersects the ecliptic at (0, $1.25~\mbox{R}_{\odot}$ , 0) from Sun center. The 81 data points are separated in intervals of $0.05~\mbox{R}_{\odot}$ and points extend from (0, $1.25~\mbox{R}_{\odot}$ , - $2.0~\mbox{R}_{\odot}$ ) to (0, $1.25~\mbox{R}_{\odot}$ , $2.0~\mbox{R}_{\odot}$ ). The measured pB ratios are used to measure temperature and speed, then we compare with true temperature and speed in the plane of the sky, and quantify the difference, which is a systematic error associated with using modeled pB ratios, based on a symmetric corona, to compare with measured pB ratios, on an asymmetric corona. This understanding is reached by allowing the coronal model to rotate a full circle in intervals of $1^{\circ}$ and illuminating the lines of sight with both symmetric and asymmetric coronal atmospheres about the plane of the sky.

Color of the Corona Continuum of July 11, 1991

The color of the coronal continuum was determined from observations in order to search for manifestations of coronal expansion. A brief review of studies determining the color of the coronal continuum finds that the previously obtained results are inconsistent. The color index for the coronal continuum is defined. The necessity of the use of a relative color index is substantiated. RCI estimates of expected values are made with respect to the electron speed. A two-dimensional RCI distribution for the corona of July 11, 1991, was constructed. Comparison of the distribution with the coronal structure illustrates the absence of uniformity of the coronal and photospheric spectra and reveals reddening with distance over the entire corona at all positional angles. It is noted that the RCI distribution for the corona on July 11, 1991, and that earlier obtained for the corona on March 29, 2006, are the first confirmations of theoretical calculations on the shift of the continuum spectrum to the red side due to electron fluxes propagating from the Sun throughout the corona.

An asymptotic preserving well-balanced scheme for the isothermal fluid equations in low-temperature plasmas at low-pressure

We present a novel numerical scheme for the efficient and accurate solution of the isothermal two-fluid (electron + ion) equations coupled to Poisson's equation for low-temperature plasmas at low-pressure. The model considers electrons and ions as separate fluids, comprising the electron inertia and space charge regions. The discretization of this system with standard explicit schemes is constrained by very restrictive time steps and cell sizes related to the resolution of the Debye length, electron plasma frequency, and electron sound waves. Both sheath and electron inertia are fundamental to fully explain the physics in low-pressure and low-temperature plasmas. However, most of the phenomena of interest for fluid models occur at speeds much slower than the electron thermal speed and are quasi-neutral, except in small charged regions. A numerical method that is able to simulate efficiently and accurately all these regimes is a challenge due to the multiscale character of the problem. In this work, we present a scheme based on the Lagrange-projection operator splitting that preserves the asymptotic regime where the plasma is quasi-neutral with massless electrons. As a result, the quasi-neutral regime is treated without the need of an implicit solver nor the resolution of the Debye length and electron plasma frequency. Additionally, the scheme proves to accurately represent the dynamics of the electrons both at low speeds and when the electron speed is comparable to the thermal speed. In addition, a well-balanced treatment of the ion source terms is proposed in order to tackle problems where the ion temperature is very low compared to the electron temperature. The scheme significantly improves the accuracy both in the quasi-neutral limit and in the presence of plasma sheaths when the Debye length is resolved. In order to assess the performance of the scheme in low-temperature plasmas conditions, we propose two specifically designed test-cases: a quasi-neutral two-stream periodic perturbation with analytical solution and a low-temperature discharge that includes sheaths. The numerical strategy, its accuracy, and computational efficiency are assessed on these two discriminating configurations.

Observation of the Relativistic Reversal of the Ponderomotive Potential.

The secular dynamics of a nonrelativistic charged particle in an electromagnetic wave can be described by the ponderomotive potential. Although ponderomotive electron-laser interactions at relativistic velocities are important for emerging technologies from laser-based particle accelerators to laser-enhanced electron microscopy, the effects of special relativity on the interaction have only been studied theoretically. Here, we use a transmission electron microscope to measure the position-dependent phase shift imparted to a relativistic electron wave function when it traverses a standing laser wave. The kinetic energy of the electrons is varied between 80 and 300keV, and the laser standing wave has a continuous-wave intensity of 175 GW/cm^{2}. In contrast to the nonrelativistic case, we demonstrate that the phase shift depends on both the electron velocity and the wave polarization, confirming the predictions of a quasiclassical theory of the interaction. Remarkably, if the electron's speed is greater than 1/sqrt[2] of the speed of light, the phase shift at the electric field nodes of the wave can exceed that at the antinodes. In this case there exists a polarization such that the phase shifts at the nodes and antinodes are equal, and the electron does not experience Kapitza-Dirac diffraction. Our results thus provide new capabilities for coherent electron beam manipulation.

Landau quantization effects on hybrid waves in semiconductor plasmas

The impact of Landau quantization on the lower hybrid waves (LHWs) exciting in the semiconductor plasmas, due to classical electron beam, is studied. The quantum hydrodynamic model is employed to derive the dispersion relation of low-frequency electrostatic waves for instability analysis of the LHWs. The quantum effects include Fermi degenerate pressure, Bohm potential, Landau quantization, and exchange-correlation potential for semiconductor plasma species. The dispersion relation is elaborated both quantitatively and qualitatively for the special case of GaAs in the presence of external magnetic field $$\mathbf{B}_0$$. The impact of different plasma parameters such as density ratios of electrons and holes $$\alpha $$, beam temperature $$T_{\mathrm{b}}$$, speed of beam electrons $$v_0$$, propagation angle $$\theta $$, cyclotron frequency $$\omega _{\mathrm{ce}}$$, temperature of electrons and holes $$T_{\mathrm{e}}$$, $$T_{\mathrm{h}}$$ and Landau quantization $$\eta $$, on the dispersion relation of LHWs, is studied. The instability of the LHWs remarkably increases by increasing the concentration of the semiconductor electrons, propagation angle of the wave vector and the beam speed, for the magnetic quantization parameter. However, the instability decreases by increasing the temperature of beam. It is noticed that at $$(T_{\mathrm{b}}>v_0)$$, the $$\eta $$ has no effect on the instability.

Electron–Langmuir wave resonance in three dimensions

In the one-dimensional (1D) treatment of Langmuir wave generation by a particle distribution via the kinetic beam instability, there is a one-to-one resonance between the electron speed v and the phase speed vϕ of the wave. The 1D condition for wave growth is ∂f/∂v>0 with v=vϕ, and f(v) evolves due to quasilinear relaxation toward a plateau distribution ∂f/∂v=0. We show here that none of these results apply in a 3D treatment of the problem. For a wave with wavevector k and phase speed vϕ, there is a many-to-one resonance with all electrons with v>vϕ moving obliquely to k. Although growth requires a region with ∂f/∂v>0 below a peak in f(v), the growth can be driven primarily by particles above the peak where ∂f/∂v<0, and growth can even occur at phase velocities vϕ where ∂f/∂v|v=vϕ<0. Resonance at v≫vϕ favors diffusion of the particle distribution in angle, rather than plateau formation. These properties imply that intuition based on the 1D model can be seriously misleading, with far-reaching implications for modeling phenomena such as type III solar radio bursts.

Study on the Discharge Characteristics of Single-Pulse Discharge in Micro-EDM.

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.

Statistics of Reconnecting Current Sheets in the Transition Region of Earth's Bow Shock

AbstractWe have conducted a comprehensive survey of burst mode observations of Earth's bow shock by the Magnetospheric Multiscale mission to identify and characterize current sheets associated with collisionless shocks, with a focus on those containing fast electron outflows, a likely signature of magnetic reconnection. The survey demonstrates that these thin current sheets are observed within the transition region of approximately 40% of shocks within the burst mode data set of Magnetospheric Multiscale. With only small apparent bias toward quasi‐parallel shock orientations and high Alfvén Mach numbers, the results suggest that reconnection at shocks is a universal process, occurring across all shock orientations and Mach numbers. On examining the distributions of current sheet properties, we find no correlation between distance from the shock, sheet width, or electron jet speed, though the relationship between electron and ion jet speed supports expectations of electron‐only reconnection in the region. Furthermore, we find that robust heating statistics are not separable from background fluctuations, and thus, the primary consequence of reconnection at shocks is in relaxing the topology of the disordered magnetic field in the transition region.

Relativistic Reduction of the Electron-Nucleus Force in Bohr’s Hydrogen Atom and the Time of Electron Transition between the Neighbouring Quantum Energy Levels

The aim of the paper is to get an insight into the time interval of electron emission done between two neighbouring energy levels of the hydrogen atom. To this purpose, in the first step, the formulae of the special relativity are applied to demonstrate the conditions which can annihilate the electrostatic force acting between the nucleus and electron in the atom. This result is obtained when a suitable electron speed entering the Lorentz transformation is combined with the strength of the magnetic field acting normally to the electron orbit in the atom. In the next step, the Maxwell equation characterizing the electromotive force is applied to calculate the time interval connected with the change of the magnetic field necessary to produce the force. It is shown that the time interval obtained from the Maxwell equation, multiplied by the energy change of two neighbouring energy levels considered in the atom, does satisfy the Joule-Lenz formula associated with the quantum electron energy emission rate between the levels.

Calculation of the Spinning Speed of a Free Electron

In a recent work, we calculated the magnetic field inside a free electron due to its spin, and found it to be about B = 8.3 × 1013 T. In the present study we calculate the spinning speed of a free electron in the current loop model. We show that spinning speed is equal to the speed of light. Therefore it is shown that if electron was not spinning the mass of electron would be zero. But since spinning is an unseparable part of an electron, we say that mass of electron is non-zero and is equal to (m = 9.11 × 10−28 g).

Self-induced Scattering of Strahl Electrons in the Solar Wind

Abstract We investigate the scattering of strahl electrons by microinstabilities as a mechanism for creating the electron halo in the solar wind. We develop a mathematical framework for the description of electron-driven microinstabilities and discuss the associated physical mechanisms. We find that an instability of the oblique fast-magnetosonic/whistler (FM/W) mode is the best candidate for a microinstability that scatters strahl electrons into the halo. We derive approximate analytic expressions for the FM/W instability threshold in two different β c regimes, where β c is the ratio of the core electrons’ thermal pressure to the magnetic pressure, and confirm the accuracy of these thresholds through comparison with numerical solutions to the hot-plasma dispersion relation. We find that the strahl-driven oblique FM/W instability creates copious FM/W waves under low-β c conditions when , where U 0s is the strahl speed and w c is the thermal speed of the core electrons. These waves have a frequency of about half the local electron gyrofrequency. We also derive an analytic expression for the oblique FM/W instability for β c ∼ 1. The comparison of our theoretical results with data from the Wind spacecraft confirms the relevance of the oblique FM/W instability for the solar wind. The whistler heat-flux, ion-acoustic heat-flux, kinetic-Alfvén-wave heat-flux, and electrostatic electron-beam instabilities cannot fulfill the requirements for self-induced scattering of strahl electrons into the halo. We make predictions for the electron strahl close to the Sun, which will be tested by measurements from Parker Solar Probe and Solar Orbiter.

Streaming instability of dust-acoustic mode with helical wavefronts

Making use of the kinetic approach for plasma species, the electrostatic twisted dust-acoustic (DA) waves are studied in a collisionless unmagnetized multi-component dusty plasma consisting of electrons, singly ionized positive ions and charged massive dust grains. The Vlasov-Poisson equations are coupled together to obtain a generalized response function by using the Laguerre-Gaussian (LG) perturbed electrostatic potential and distribution function in the paraxial limit. The dispersive properties and growth rate instability of twisted DA waves are examined with distinct OAM states in a multi-component dusty plasma. Various significant modifications associated with the real wave frequency and growth rate are shown with respect to twist parameter and dust concentration. It is examined that dust concentration enhances the growth rate of twisted DA waves, whereas an increase in twist parameter reduces the growth rate instability. The excitation of twisted DA mode is also found to enhance with streaming speed of inertialess electrons. Our results may be useful for particle transport and trapping phenomena due to wave excitation in laboratory dusty plasmas.