Motion Of Trapped Electrons Research Articles

WGMs on-Chip Design for Interdisciplinary Studies

Light in a PANDA ring resonator system for coated and uncoated materials have been proposed and discussed. The input waves (lights) can be in the forms of soliton, Gaussian pulses, photon or matter wave. The trapped electron motion around the PANDA ring can also be generated, in which the matter wave concept is formed within the PANDA ring waveguide. From the results, we found that the whispering gallery mode (WGM) can be generated due to coupling effects of the two nonlinear side rings, which have shown many interesting results and aspects. We found that four behaviors of light, for instance, fast, slow, stopping and storing can be manipulated and seen simultaneously by PANDA ring planar waveguide, which can be fabricated and tested on-chip, which is also suitable to implement in the laboratory.

Micro Energy Source Using WGMs of Wave in Small Scale Optical Device

Simulation results of forms of waves in a ring resonator system known as a PANDA ring resonator for coated and uncoated materials have been proposed and discussed. The input waves (lights) can be in the forms of soliton, Gaussian pulses, photon or matter wave. The trapped electron motion around the PANDA ring can also be generated, in which the matter wave concept is formed within the PANDA ring waveguide. From the results, we found that the whispering gallery mode (WGM) can be generated due to coupling effects of the two nonlinear side rings, which have shown many interesting results and aspects, especially for energy applications, which can be fabricated and tested on-chip.

Polyimide surface modification by linear stationary plasma thruster

Compared to the conventional circular type, the horse-track shaped proto-type linear stationary plasma thruster (LSPT) was designed and fabricated. A cathode with LaB6 emitter was adopted for trapped electron motion along ceramic wall as an electron source generally attached in the conventional cylindrical SPT. Nevertheless it has a little lower ion beam current density of 0.5 mA/cm 2 than conventional cylindrical type SPT with 50 mm diameter, it was also proved very effective in surface modification of polymers. Reactive O 2 + and N 2O + ion beam generated from LSPT can reduce the wetting angle 70° of polyimide (PI) down to the small angle less than 10°. 2-layer non-adhesive flexible copper clad laminate (FCCL) with Cu(8 µm)/Cu(200 nm)/Ni–Cr–Mo (20 nm)/PI(38 µm) was fabricated by using LSPT in 300 mm roll-to-roll vacuum coater. Peel strength was 0.66 kgf/cm for as-received sample and 0.42 kgf/cm after thermal test for 168 h at 150 °C, which shows a little higher performance than commercial ones.

In SituDiscovery of an Electrostatic Potential, Trapping Electrons and Mediating Fast Reconnection in the Earth's Magnetotail

Anisotropic electron phase space distributions, f, measured by the Wind spacecraft in a rare crossing of a diffusion region in Earth's far magnetotail (60 Earth radii), are analyzed. We use the measured f to probe the electrostatic and magnetic geometry of the diffusion region. For the first time, the presence of a strong electrostatic potential (1 kV) within the ion diffusion region is revealed. This potential has far reaching implications for the reconnection process; it accounts for the observed acceleration of the unmagnetized ions out of the reconnection region and it causes all thermal electrons be trapped electrostatically. The trapped electron motion implies that the thermal part of the electron distributions are symmetric around v( parallel)=0: f(v( parallel),v( perpendicular)) approximately f(-v( parallel),v( perpendicular)). It follows that the field aligned currents in the diffusion region are limited and fast magnetic reconnection is mediated.

Experimental evidence of fast reconnection via trapped electron motion

Magnetic reconnection in collisionless magnetohydrodynamic plasmas is studied under controlled conditions in toroidal X-line configurations formed in the center of the Versatile Toroidal Facility [J. Egedal et al., Rev. Sci. Instrum. 71, 3351 (2000)]. Profiles of key parameters are measured during driven reconnection pulses in the reproducible plasma discharges. The experimental results prove to be highly sensitive to the boundary conditions applied. In the configuration with “open” boundaries reconnection is fast; the measured current densities are about three orders of magnitude below those predicted based on classical Spitzer resistivity. These small current densities are consistent with the electrons following toroidally trapped orbits. Further, the size of the electron diffusion region scales with the drift orbit width of the trapped electrons. Experiments conducted with “closed” boundaries yield significantly different results. In this configuration the electrons are not trapped toroidally and large current densities are permitted to develop. These currents reduce significantly the reconnection rate in the closed configurations.

Imaging the Photoionization of Individual CdSe/CdS Core−Shell Nanocrystals on n- and p-Type Silicon Substrates with Thin Oxides

The low-intensity photoionization of individual semiconductor nanocrystals, at 23 °C in dry nitrogen, is time-resolved over many hours for both S (532-nm excitation) and P (395-nm excitation) nanocrystal excited states using electrostatic force microscopy. Over 7000 calibrated charge measurements have been made on 14- and 21-Å-thick oxide layers. Photoexcited electrons tunnel across the oxide into the silicon, and multiple charges can build up on individual nanocrystals at intensities of only 0.1−0.01 W/cm2. The silicon dopant type influences the net nanocrystal charging via the interfacial band bending; P-type subtrates show a faster nanocrystal reneutralization rate due to their higher interfacial electron concentration. There is a huge range of photoionzation behavior for individual nanocrystals. This behavior is different for 395- and 532-nm excitation in the same nanocrystal. This individuality seems in part to reflect tunneling through spatially localized defect states in the oxide. The line widths of spatial charge images of individual nanocrystals and the semicontinuous rate of charge re-neutralization after excitation suggest that we observe trapped electron motion in the adjacent oxide and/or on the nanocrystal surface, in addition to the ionized nanocrystal. On average, tunneling of the excited P electron is faster by 1−2 orders of magnitude than that of the S electron; the data show direct photoionization from the excited P state. A kinetic model is developed, including the effect of charging energy on tunneling rate, and applied to ensemble average behavior. There is no quantitative agreement of the tunneling-rate dependence on oxide thickness and excitation energy with the simple 1D effective mass tunneling model. However, overall observed trends are rationalized in light of current thin-oxide tunneling literature.

Evaluation of the Lorentz group Lie algebra map using the Baker-Cambell-Hausdorff formula

This paper presents a formulation of a numerical integrator for charged particles. The original idea of the integrator scheme was given several years ago. The main topics of this paper is the reformulation of the integrator as the Lorentz group Lie algebra map and modifications for practical use. Two numerical simulation examples, trapped electron motion in a cusp magnetic field and electron pendulum motion in the free electron laser (FEL), show the validity of this new formulation.

Possibility of VLF-signal non-linear spectrum broadening in the magnetosphere

The interaction between oblique electrostatic whistler mode waves and thermal electrons in the magnetosphere results in generation of sidebands. Computer simulations show that sideband instabilities develop in non-monochromatic waves, though there is no trapped electron motion in the field of initially excited waves. Additional maxima in the wave spectrum appear at sideband frequencies that differ from the main frequency by ƒ t~ 0.5 kHz for waves of amplitude E ~ 3 mV m −1. The amplitude of sideband maxima can be compared with the amplitude of the main mode. This means of modification of whistler wave spectra in the magnetosphere is complementary to the Doppler broadening mechanism, and is considerable for intense signals.

Effect of a transition between regular and stochastic electron motion on the evolution of an obliquely propagating Langmuir wave

The evolution of an obliquely propagating Langmuir wave is considered, with emphasis on determining the effect of a transition between regular and stochastic electron motion. The wave has three distinct evolution regimes, whose locations in parameter space depend roughly on the relative sizes of the linear damping rate γ, the electron bounce frequency ωb and the electron cyclotron frequency Ω. When ωb<γ, the wave is in the linear regime and simply damps away. When γ<ωb<Ω, the wave evolution is dominated by regular, trapped electron motion in individual resonances. It is shown that when the propagation angle increases to about 14°, the trapping oscillations present in parallel propagating waves disappear due to phase mixing of the different bounce frequencies. When γ<Ω<ωb, the wave evolution is dominated by stochastic particle motion from resonance to resonance. It is shown that when a transition is made from the trapping to the stochastic regime, the final (t=∞) wave amplitude significantly decreases, due to the increased ability of the electrons to take energy from the wave. Finally, simulation results which verify key aspects of the theory are reported.

Jovian S-burst observations at 32 MHz

JUPITER emits highly sporadic and intense radio emission in the 0.45–40 MHz frequency range1. Several high-resolution observations below 28 MHz have revealed that a significant fraction of this radiation, perhaps 25%, is comprised of S bursts, which are characterised by rapid negative drift rates R (tens of MHz s−1) and extremely narrow instantaneous band-widths (≤200 kHz2–7. The probability of observing S bursts, which are associated exclusively with source regions B and C, is determined to a large extent by the geocentric phase of Io. This has led to the widely-held conclusion that the emission is beamed from the planet's Io-associated magnetic flux tube (IFT). S-burst emission models generally assume simple adiabatic motion of trapped electrons accelerated at Io and radiating at or close to the local electron gyrofrequency (refs 8–10). The details of the emission process are unclear and at present offer no restrictions as to the sign of R; however, as the S bursts exhibit negative frequency drift (R<0), we shall speak only in terms of electron bunches radiating as they stream outward from their mirror point near the IFT foot. In this context |R| is predicted to increase rapidly from zero to some maximum value (depending upon electron energy) as the particles execute this motion. In terms of frequency, this region of the northern hemisphere IFT corresponds to fg ≳ 27 MHz. A determination of R at several points in this frequency range is then a critical test of models incorporating a trapped-electron hypothesis. Accordingly, we present here a preliminary report on observations conducted in this range.