Observed Energy Loss Research Articles

An innovative mechanism for transmitting power from the pistons in internal combustion engines

Reciprocating internal combustion engines are common and thus important engines due to the many advantages they provide. Despite significant improvements being made to these types of engines in recent decades, however, they still suffer from low efficiency due to large losses in produced energy, which occur for multiple reasons. The crank mechanism is responsible for much of the observed energy loss, however.In the current study, a new mechanism is suggested to transmit kinetic energy directly from the pistons, thus reducing energy losses associated with the crankshaft. This new mechanism eliminates the crankshaft from power transmission, limiting it to syncing piston movement. The pistons are then modified to mate with partial teething gears, which then transmit the kinetic energy directly from the pistons without this energy being negatively affected as it is by the angular position of the crank units. The testing results show that the power produced during the power stroke in the suggested engine is twice corresponding output of a classical engine.

Electron energy loss spectroscopy and first-principles study of GaN via Zn doping

The electronic structure of GaN and GaN:Zn was investigated by electron energy loss spectroscopy and first-principles calculations. In the low-loss spectrum, the interband transitions are assigned to the observed energy loss peaks. After Zn doping, impurity levels are introduced to the density of states and hybrid orbitals of N 2p and Zn 3d are formed around the Fermi level. In the nitrogen K-edge, an additional peak was observed due to the formation of donor defect states. A core-hole effect is believed to be significant for simulation of the N K-edge for both GaN and GaN:Zn.

Investigation of the energy loss of I in Au at energies below the Bragg peak

The energy loss of iodine in gold was investigated at energies below the Bragg peak. With the present work, the range of the available experimental data is extended to significantly lower energies, while the nuclear stopping power contribution is taken into account. Experiments were performed on thin film targets in reflection geometry. Electronic stopping cross sections were extracted by different approaches from experimental spectra. The obtained results have been compared to tabulated values from SRIM and previously published experimental data, where available. For all energies the obtained values are consistently higher than predicted by SRIM. Monte Carlo simulations (TRIM) have been performed to study path length distributions and the influence of nuclear stopping on the total energy loss. The results from the calculations indicate that the experimental geometry might be an important factor affecting the observed energy loss due to a selection of specific trajectories.

Electronic interactions of medium-energy ions in hafnium dioxide

In this article, the electronic interaction of medium-energy ions with hafnium dioxide is studied. Stopping cross sections for He ions in the energy range from 30 to 160 keV have been measured in backscattering experiments from thin films of HfO${}_{2}$ on Si using time-of-flight medium-energy ion scattering. The observed energy loss for helium ions is found to be high compared to expectations from earlier results for hydrogen in HfO${}_{2}$, a result which indicates a contribution from energy-loss processes that is different from direct excitation of electron-hole pairs in close collisions. Furthermore, data exhibit a significant deviation from velocity proportionality. A discussion of the results, together with data from studies for H and He in SiO${}_{2}$, show characteristic differences which are traced back to different electronic structures of the target materials and their influence on the charge-exchange channels that are active in the interaction with helium. Charge exchange, in turn, via shifted mean-charge states, will influence the observed ionization along the ion track. The results can furthermore serve as reference values for ion-beam-based depth profiling at medium and low ion energies.

Energy loss and fragmentation of 3 keV [formula omitted] ions at grazing scattering from a KCl(0 0 1)

Charge state, angular and energy distributions of reflected projectiles are measured when 3 keV C 60 + , 2 + ions are scattered from a clean and flat KCl(0 0 1) surface under grazing incidence. The dominant charge state is found to be C 60 + irrespective of the incident charge state as is expected from the electronic structure of KCl and C 60 ions. The observed angular distribution has a well defined peak at a specular angle, indicating that the normal energy is not dissipated during the grazing angle scattering. In spite of no dissipation of the normal energy we observe the fragmentation of the scattered C 60 + ions. The energy transferred from the parallel energy to the internal excitations was estimated from the observed fragment distribution. The transferred energy changes from almost 0 to ∼15 eV when the angle of incidence changes from 1° to 6°, which is less than 10% of the observed energy loss of the C 60 + ions.

Alkali ion scattering from Ag(0 0 1) and Ag thin films at low and hyperthermal energies

We have investigated the scattering of K+ and Cs+ ions from a single crystal Ag(001) surface and from a Ag–Si(100) Schottky diode structure. For the K+ ions, incident energies of 25eV to 1keV were used to obtain energy-resolved spectra of scattered ions at θi=θf=45°. These results are compared to the classical trajectory simulation safari and show features indicative of light atom-surface scattering where sequential binary collisions can describe the observed energy loss spectra. Energy-resolved spectra obtained for Cs+ ions at incident energies of 75eV and 200eV also show features consistent with binary collisions. However, for this heavy atom-surface scattering system, the dominant trajectory type involves at least two surface atoms, as large angular deflections are not classically allowed for any single scattering event. In addition, a significant deviation from the classical double-collision prediction is observed for incident energies around 100eV, and molecular dynamics studies are proposed to investigate the role of collective lattice effects. Data are also presented for the scattering of K+ ions from a Schottky diode structure, which is a prototype device for the development of active targets to probe energy loss at a surface.

Electron-phonon interaction in a quantum wire in the Bloch-Gruneisen regime

We investigate the one-dimensional electron gas (1DEG) interaction with three-dimensional (3D) acoustic phonons in a quantum wire (QWR) by calculating the temperature $T$ and electron concentration ${n}_{l}$ dependence of phonon drag thermopower ${S}^{g}$ and energy loss rate $P$ in the Bloch-Gruneisen regime taking account of static screening. Electron scattering by acoustic phonons through piezoelectric field and deformation potential is considered. At very low temperature, ${S}^{g}$ and $P$ are dominated by the contribution due to piezoelectric scattering. The contribution due to deformation potential becomes significant at relatively higher temperature. The power laws for $T$ and ${n}_{l}$ dependences of ${S}^{g}$ and $P$ are obtained. The screening affects weakly the power of $T$ and significantly the power of ${n}_{l}$. The interesting feature is that ${S}^{g}$ is reduced by a factor of ${({\ensuremath{\nu}}_{s}∕{\ensuremath{\nu}}_{F})}^{2}$, where ${\ensuremath{\nu}}_{s}$ is the sound velocity and ${\ensuremath{\nu}}_{F}$ is the Fermi velocity, compared to that in two-dimensional electron gas (2DEG). A qualitative comparison is made between the calculated and experimentally observed energy loss rate in etched InGaAs QWRs. Herring's law ${S}^{g}{\ensuremath{\mu}}_{p}\ensuremath{\sim}{T}^{\ensuremath{-}1}$ (${\ensuremath{\mu}}_{p}$ is the phonon limited mobility) is validated in QWR. Our results are compared with those in 2DEG.

Energy loss of 15-keV Arq+ (q=1–3) ions reflected from a KCl([formula omitted]) surface

Energy losses of reflected Ar+ ions are measured when 15-keV Arq+ (q=1–3) ions are incident on a KCl(001) surface at a grazing angle θi. The observed energy loss for Ar+ incidence increases almost linearly with θi from ∼10 eV at θi=10 mrad to ∼200 eV at θi=50 mrad. The energy losses for Ar2+ and Ar3+ incidence show the similar θi-dependence, but the energy loss is larger than that of Ar+ by ∼25 and ∼40 eV for Ar2+ and Ar3+, respectively. The position-dependent stopping powers were derived from the observed energy losses. The obtained stopping power is almost independent of the incident charge at a distance x smaller than ∼1.5 Å, while the stopping power increases with q at x≳ 1.5 Å. This indicates that the critical distance for charge exchange is ∼1.5 Å in the present case.

Random and channeled energy loss of 33.2-TeV Pb nuclei in silicon single crystals

Measurements of the energy loss and the energy-loss distributions of 160 GeV/amu fully stripped lead ions traversing a silicon single crystal are presented. The energy loss is measured using the silicon crystal as an intrinsic detector. Hence the measured energy loss is a restricted energy loss excluding very large energy transfers. For random incidence, the observed energy-loss distributions are very narrow and Gaussian-like. For well-channeled particles, the energy loss is strongly reduced as compared to so-called random particles. The observed energy loss is compared to calculations as well as simulations. Due to the small straggling, the energy-loss distributions are reflecting directly the distribution in transverse energy.

Energy loss of 6 MeV/u iron ions in partially ionized helium plasma

The energy loss of fast iron ions in a partially ionized helium plasma was investigated experimentally. Z-pinch discharge with a peak current of 60 kA produced a plasma column with a maximum electron density of 2.5×10 18 cm −3. We injected 6-MeV/u iron ions into the plasma and monitored them with a micro-channel plate stop detector at 3.8 m downstream from the target. We determined the energy loss of these ions from the increase in the time of flight. The observed energy loss was compared with the calculated value taking into account the dynamic change of the effective charge of the projectile ions in the target. The results indicate that the recombination rate for the projectile ions was much smaller than the predicted value.

Energy loss of deuterons in 3He gas: a threshold effect

The energy loss of deuterons in 3He gas was measured at E d = 15 to 100 keV using the 3He pressure dependence of the 3He(d,p)4He cross-section at a given incident energy. At the highest energies, the observed energy loss is in good agreement with a standard compilation. However, with decreasing energy the experimental values drop steadily below the theoretical values and near E d = 18 keV they drop sharply (within 1 keV) reaching the domain of nuclear stopping power. This threshold behavior is due to the minimum 1s → 2s electron excitation of the He target atoms, i.e. it is a quantum effect. Some consequences are discussed.

Position-dependent stopping power of low velocity rare gas atoms at a SnTe(0 0 1) surface

Energy losses of 15–30 keV Ne+, Ar+ and Kr+ ions specularly reflected from a SnTe(001) surface are measured. Because more than 98% of the reflected ions are neutral, the observed energy loss can be considered as the result of atom–surface interactions. From the observed energy losses, position-dependent stopping powers of the SnTe(001) surface for neutral atoms are derived. The obtained stopping powers are compared with the theory of the stopping power for low velocity ions with help of the local density approximation. While the agreement between the experimental and theoretical results is excellent for Ar and Kr atoms, the experimental stopping is about twice larger than the theoretical one for Ne atoms. This discrepancy can be explained in terms of the effect of excited atoms on the stopping power.

Energy losses of MeV B clusters in solids

Energy losses of 0.8 MeV/atom small B n ( n ≤ 4) clusters transmitted through thin carbon foils ranging from 2 to 16 μg cm −2 have been measured. The ratio of observed energy loss per atom of B n clusters to the energy loss of single B ions shows the enhancement at thinner foils, which indicates the vicinage effect in the cluster-solid interaction. The pulse-height defect for a cluster ion in a solid-state detector was observed.

On the dynamics and instability of bubbles formed during underwater explosions

Abstract Dynamics of explosion bubbles formed during underwater detonations are studied experimentally by exploding fuel (hydrogen and/or carbon monoxide)–oxygen mixture in a laboratory water tank. Sub-scale explosions are instrumented to provide detailed histories of bubble shape and pressure. Using geometric and dynamic scaling analyses it has been shown that these sub-scale bubbles are reasonable approximations of bubbles formed during deep sea underwater explosions. The explosion bubble undergoes pulsation and loses energy in each oscillation cycle. The observed energy loss, which cannot be fully explained by acoustic losses, is shown here to be partly due to the excitation of instability at the interface between the gaseous bubble and the surrounding water. Various possible mechanisms for the dissipation of bubble energy are addressed. The analysis of the experimental data gives quantitative evidence (confirmed by recent numerical studies) that the Rayleigh–Taylor instability is excited near the bubble minimum. The dynamics of the bubble oscillation observed in these experiments are in good agreement with experimental data obtained from deep sea explosions

Energy losses of B clusters transmitted through carbon foils

We have measured energy losses of 0.8-MeV/atom B n ( n ≤ 4) clusters transmitted through thin carbon foils (2–17 μg/cm 2). The ratio of observed energy loss per atom of B n clusters to the energy loss of isolated B ions is larger than unity at thinner foils and approaching unity with increasing foil thickness, which indicates the vicinage effect in the cluster–solid interaction.

Evidence for Dipole-Dipole Hopping of GaAs Quantum Well Excitons

We present measurements of the energy relaxation of quasi-two-dimensional excitons in the hopping regime. Under a variety of experimental conditions, the mean energy decays in proportion to $\mathrm{ln}t$. We interpret this result naturally in a model based on the dipole-dipole mechanism for energy loss hops. The model achieves semiquantitative agreement with the observed energy loss rates.

Energy loss of scattered ions at glancing-angle incidence on the crystal surface

Experimental findings of glancing-angle scattering of energetic ions are reviewed with particular emphasis on the energy loss of ion during scattering. The position-dependent stopping power of the surface which is derived from the angular dependence of observed energy loss is explained in terms of single and distance electron excitations of surface electrons. For the ions with velocities less than the Fermi velocity of target valence electrons, it is shown that the stopping power of a surface is determined only by the elastic collisions of the ion with valence electrons. From the analysis of the energy losses of 12–30 keV He ions reflected from the (001) surface of SnTe, a method is proposed to derive the electron density distribution averaged over the plane parallel to the surface from this position-dependent stopping power.

Excitation of neutral molecules: Probing the dynamics by translational energy spectrometry

AbstractHigh‐resolution translational energy spectroscopy has been applied to the study of collision‐induced excitation of neutral diatomic and polyatomic molecules using molecular projectile ions. Techniques to simulate the experimentally observed energy loss spectra are explored and information regarding the relative oscillator strengths to different electronic states of the neutral targets has been obtained. The effects of changing the quantal description of the projectile are studied and the results are understood within the domain of wavefunction overlaps. Concomitant calculations of the wavefunction overlap of the highest occupied molecular orbitals of the collision partners yield results which are consistent with the experimental observations.

Energy loss of carbon-transmitted 1-MeV H2+ ions.

Energy losses of 1-MeV ${\mathrm{H}}_{2}^{+}$ ions passing through carbon foils of 2--8 \ensuremath{\mu}g/${\mathrm{cm}}^{2}$ thickness have been measured. The observed energy loss increases linearly with the target thickness and shows an offset, 0.4 keV, at zero thickness. The stopping power derived from the observed energy losses is 1.15 times as large as the sum of the stopping powers for two single ${\mathrm{H}}^{+}$ of the same velocity. Stopping powers for ${\mathrm{H}}_{2}^{+}$ ions and diprotons are calculated with the first Born approximation. The calculated stopping power for the diproton agrees quite well with the one observed. This indicates that the observed ${\mathrm{H}}_{2}^{+}$ ions traverse the target as diprotons after the loss of the binding electrons upon entrance into the foil and recapture target electrons at the exit surface. The observed energy-loss offset at zero thickness also supports this scenario.

Charge determination of fission fragments via energy loss and X-ray measurements

Energy loss of fission fragments of specified charges and kinetic energies have been measured with a gas detector telescope. The singles data from the telescope (DE-E R) and coincidence data with a HP Ge X-ray detector (DE-E R-X) were taken using a 252Cf fission source. An empirical expression for the dependence of Z eff on charge and energy of fragments has been determined by fitting the observed energy loss behaviour of the fission fragments. The resolution in the measurement of charge from event by event analysis of DE-E R data for the light fragment mass group was found to be about 1.8 charge units (FWHM). The present data were analysed to determine the fragment charge distribution as well as the X-ray yield per fragment in 252Cf fission.