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To clarify the combustion process of a modular charge system with a primer gap, the rules governing the cartridge movement and pressure change in the chamber are analyzed. Based on the characteristics of the modular charge system, an axisymmetric two-phase flow model of the interior ballistics is established, with the monotonic upward-centered scheme for conservation laws adopted to calculate the combustion process. Compared with the experimental results, the difference in the peak pressure is less than 5%, which indicates that the mathematical model and scheme are reliable and accurate. The results show that, during the initial stage of ignition, the combustible container remains unbroken, and the gas and solid particles are prevented from spreading to the chamber by the end cap of the cartridge. Thus, only the gas inside the igniter tube influences the flow field in the chamber. After the combustible container has broken, the gas and solid particles move rapidly toward the cavity from the combustible container. The axial movement of solid particles is more intense than that of the gas particles, but the radial movement of solid particles is relatively weak. Furthermore, the existence of the primer gap leads to a delay in the ignition time of the solid particles, which delays the rupture time of the igniter tube and the module cartridge. [ABSTRACT FROM AUTHOR]

Two-phase flow numerical methods are applied in internal ballistics widely, which has made higher fidelity analysis with minimal cost become an urgent demand. Current methods are based on independent dimension, and there is no definite conversion criterion and data transmission method, which have limited the application of efficient hybrid models applied to calculation. In this paper, we propose a hybrid method by linking a two dimensional (2D) model to a one dimensional (1D) model for two-phase flow. First, 1D and 2D two-phase flow models are established according to the flow field states in different phases. Next, the criterion of conversion between the two models is established, which is a quantitative index to judge the degree of radial effect and axial effect. Finally, dimension transformation in the radial direction and grid mergence in the axial direction are conducted to complete the whole computing model. The simulation results show that the hybrid method is more efficient in the interior ballistic process and maintains the level of trust in classical codes. Compared with the 2D method, the hybrid method significantly improves the computational efficiency by 86.5%. By analyzing the state in the chamber, the accuracy of the conversion criterion is confirmed. This criterion can be used as the transformation criterion of the hybrid model to form the standard multi-dimensional calculation transformation criterion of interior ballistics and may be promising for the rapid simulation of two-phase flow in interior ballistics. [ABSTRACT FROM AUTHOR]

An excellent flame suppression effect can be achieved using a novel porous brake. To understand the flame-suppression mechanism of a porous brake, combustion using a muzzle brake is investigated. A set of internal ballistic equations is employed to provide accurate velocity and pressure for a projectile moving to the muzzle. The multispecies transport Navier–Stokes equations, which incorporate complex chemical reactions, are solved by coupling a real gas equation of state, the Soave–Redlich–Kwong model, and a detailed chemical reaction kinetic model. The development of muzzle flow with a chemical reaction is simulated, and the interaction between chemical reactions with the muzzle flow field is numerically calculated to explain the muzzle combustion mechanism with a porous brake. The underlying mechanism is analyzed in detail. The results demonstrate that, first, the gas is fully expanded in the brake, leading to a reduction in pressure and temperature at the muzzle, thereby reducing the initial flame. In addition, the shock wave weakens due to the expansion and separation process, leading to a reduction in the mixture of gas and air, ultimately resulting in a reduction in the intermediate and secondary flames. [ABSTRACT FROM AUTHOR]

Energy transport in molecules is essential for many areas of science and technology. Strong covalent bonds of a molecular backbone can facilitate the involvement of the molecule's high-frequency modes in energy transport, which, under certain conditions, makes the transport fast and efficient. We discuss such conditions and describe various transport regimes in molecules, including ballistic, diffusive, directed diffusion, and intermediate regime cases, in light of recently developed experimental and theoretical approaches. [ABSTRACT FROM AUTHOR]

The evolution of material strength within several dense particle suspensions impacted by a projectile is investigated and shown to be strongly dependent on the particle material in suspension. For stronger particles, such as silicon carbide, the shear strength of the fluid is shown to increase with the ballistic impact strength. For weaker particles, such as silica, the shear strength of the suspension is found to be independent of impact strength in this dynamic range of tests. A soft-capture technique is employed to collect ejecta samples of a silica-based shear thickening fluid, following a ballistic impact and penetration event. Ejecta samples that were collected from impacts at three different velocities are observed and compared to the benchmark particles using a Scanning Electron Microscope. The images show evidence of fractured and deformed silica particles recovered among the nominally 1 µm diameter monodisperse spheres. There is also evidence of particle fragments that appear to be the result of interparticle grinding. The trends observed in the shear strength estimates are interpreted with regards to the particle damage seen in the ejecta recovery experiments to develop a concept of the impact response of these fluids. The results suggest that particle slip through deformation is likely the dominant factor in limiting the transient impact strength of these fluids. Particularly, particle strength is important in the formation and collapse of dynamically jammed particle contact networks in the penetration process. [ABSTRACT FROM AUTHOR]

The Noble–Abel (NA) equation of state (EOS) is widely used in the interior ballistics of guns as well as rocket propulsion computations. Its simplicity and accuracy are key points for intensive computations with hyperbolic two-phase flow models considered in interior ballistics codes. An alternative formulation is examined in the present contribution through a first-order virial (VO1) equation of state. Appropriate methods for the determination of related parameters, such as specific gas constant, co-volume, and condensed material energy, for both formulations (NA and VO1) are presented. For this, a combination of closed bomb vessel experiments and thermochemical code computations is needed. An extended VO1 EOS with temperature-dependent specific heat is examined. Then, its extension to multiple reactive materials is addressed. Examples are examined for each formulation (NA and VO1) and comparisons are done with the Becker–Kistiakowsky–Wilson (BKW) EOS as reference. Several conclusions have emerged. First, a consideration of the specific heat temperature dependance in computations of the interior ballistics of guns appeared insignificant. Second, VO1 appeared to be more accurate than NA, particularly when gas density is beyond the range used for EOS parameter determination. Last, regarding mixtures of condensed reactive materials, producing burnt gas mixtures, NA again appeared to be less accurate than VO1. However, its formulation is explicit, while VO1 requires numerical solving of a non-linear equation, with consequences on computational cost. [ABSTRACT FROM AUTHOR]

This work explores the use of surface-mesh flow solvers to model solid rocket internal ballistics with arbitrary grain geometry. Specifically, a surface-vorticity approach, originally intended for external flow applications, is adapted for internal flow analysis using boundary conditions that are suitable for solid rocket motors. In this study, an enhanced panel code is shown to be capable of resolving internal rocket flowfields with a striking level of fidelity and with such a degree of computational efficiency to make it valuable in the conceptual and preliminary design of rocket motors. In this process, the vortex paneling approach embodied within FlightStream® is refined using boundary conditions appropriate for solid rocket rotational flows. The simulation results are then compared to existing analytical solutions for cylindrical and planar chamber configurations exhibiting small taper angles and uniform headwall injection. For a more realistic validation case, the space shuttle's reusable solid rocket motor (RSRM) is examined. Guided by the analytical models, simple rotational and compressibility corrections are incorporated into the solver, and the results are subsequently compared to two other computational models and experimental measurements gathered from qualification motors. For the basic configurations, our results are shown to agree well with theoretical predictions. For the RSRM case, the corrected solution agrees well with the validation data in the first half of the motor; however, it becomes less robust in the aft region unless a recirculation zone boundary patch is applied; the latter approximates the added vorticity introduced by intersegmental gaps and the submerged nozzle effects. [ABSTRACT FROM AUTHOR]

In materials, energy can propagate by means of two limiting regimes: diffusive and ballistic. Ballistic energy transport can be fast and efficient and often occurs with a constant speed. Using twodimensional infrared spectroscopy methods, we discovered ballistic energy transport via individual polyethylene chains with a remarkably high speed of 1440 m/s and the mean free path length of 14.6 Å in solution at room temperature. Whereas the transport via the chains occurs ballistically, the mechanism switches to diffusive with the effective transport speed of 130 m/s at the end-groups attached to the chains. A unifying model of the transport in molecules is presented with clear time separation and additivity among the transport along oligomeric fragments, which occurs ballistically, and the transport within the disordered fragments, occurring diffusively. The results open new avenues for making novel elements for molecular electronics, including ultrafast energy transporters, controlled chemical reactors, and sub-wavelength quantum nanoseparators. [ABSTRACT FROM AUTHOR]

We investigate ballistic vibrational energy transport through optical phonon band in oligomeric chains in the presence of decoherence. An exact solution is obtained for the excitation density in the space-time representation in the continuous limit and this solution is used to characterize the energy transport time and intensity. Three transport mechanisms are identified such as ballistic, diffusive, and directed diffusive regimes, occurring at different distances and time scales. The crossover between the two diffusive regimes is continuous, while the switch between the ballistic and diffusive mechanisms occurs in a discontinuous manner in accord with the recent experimental results on energy transport in perfluoroalkanes. [ABSTRACT FROM AUTHOR]

We have investigated the temperature dependence of ballistic mobility in a 100 nm-long InGaAs/InAlAs metamorphic high-electron-mobility transistor designed for millimeter-wavelength RF applications. To extract the temperature dependence of quasi-ballistic mobility, our experiment involves measurements of the effective mobility in the low-bias linear region of the transistor and of the collision-dominated Hall mobility using a gated Hall bar of the same epitaxial structure. The data measured from the experiment are consistent with that of modeled ballistic mobility based on ballistic transport theory. These results advance the understanding of ballistic transport in various transistors with a nano-scale channel length that is comparable to the carrier's mean free path in the channel. [ABSTRACT FROM AUTHOR]

This paper describes an experimental and a numerical study of a recently developed high-efficiency, low-resistance launching method for an underwater launcher. The so-called gas-curtain launch method overcomes the problems of poor safety and low muzzle velocity in traditional fully submerged launchers. By introducing part of the gas inside the chamber to the front of the projectile, the water inside the barrel will be driven out. A low-resistance gas passage is then provided for projectile motion in the bore, thus delivering better interior ballistics performance than that in fully submerged launchers. Experiments are carried out using a 12.7-mm underwater launcher. A pressure sensor is used to record the chamber pressure, and high-speed video recordings allow the projectile motion around the muzzle to be determined. The experimental results show that the muzzle velocity is 172.8 m/s and the maximum chamber pressure reaches 116.0 MPa in a fully submerged launch, compared with a maximum chamber pressure of only 41.8 MPa and a muzzle velocity of 177.5 m/s when the gas-curtain launch method is adopted. The significant drag reduction effect of the gas-curtain launch greatly improves the interior ballistics performance, reducing the maximum chamber pressure by about 64.1% while retaining a similar muzzle velocity. Following the experiments, a numerical model is established and simulations are performed under various ventilation mass rates. The results clarify the drag reduction mechanism and the partial characteristics of the flow field in the gas-curtain launch. [ABSTRACT FROM AUTHOR]

We report on initial observations of high velocity outflows from the ends of a rod compressed using pulsed power. 1 mm and 2 mm diameter copper rods were placed in a water bath and driven by ∼0.6 MA currents with rise times of ∼700 ns. Laser backlit framing images and streak photography showed an outflow of the material from the ends of each rod, of the initial velocity of up to 7 km/s, which began ∼500 ns after the start of the current pulse and continued throughout the experiment. Ballistics gel was used to help separate low density gas/plasma from any solid/liquid component in the outflow, successfully capturing the material from larger diameter rods (enabling an estimate of its energy) and tracing the path of the material that passed straight through the gel with smaller rods. Experimental results were compared to 1D and 2D MHD simulations performed with the Gorgon code. These suggested that the outflow had two different components, resulting from two different physical processes. Differences in the resistivity between the copper rod and stainless steel anode result in the opening of a small gap between them and ablated stainless steel being projected above the rod, which is captured in framing and streak images. Later in time, a dense copper material, pinched by the magnetic pressure, is launched—explaining the ballistics gel results. The simulations also suggest that the tamped explosion of the rod surface plays a small role in any outflow. [ABSTRACT FROM AUTHOR]

We study the transport properties of monolayer MX2 (M = Mo, W; X = S, Se, Te) n- and p-channel metal-oxide-semiconductor field effect transistors (MOSFETs) using full-band ballistic non-equilibrium Green's function simulations with an atomistic tight-binding Hamiltonian with hopping potentials obtained from density functional theory. We discuss the subthreshold slope, drain-induced barrier lowering (DIBL), as well as gate-induced drain leakage (GIDL) for different monolayer MX2 MOSFETs. We also report the possibility of negative differential resistance behavior in the output characteristics of nanoscale monolayer MX2 MOSFETs. [ABSTRACT FROM AUTHOR]

Heterostructure tunnel field-effect transistors (HTFET) are promising candidates for low-power applications in future technology nodes, as they are predicted to offer high on-currents, combined with a sub-60 mV/dec subthreshold swing. However, the effects of important quantum mechanical phenomena like size confinement at the heterojunction are not well understood, due to the theoretical and computational difficulties in modeling realistic heterostructures. We therefore present a ballistic quantum transport formalism, combining a novel envelope function approach for semiconductor heterostructures with the multiband quantum transmitting boundary method, which we extend to 2D potentials. We demonstrate an implementation of a 2-band version of the formalism and apply it to study confinement in realistic heterostructure diodes and p-n-i-n HTFETs. For the diodes, both transmission probabilities and current densities are found to decrease with stronger confinement. For the p-n-i-n HTFETs, the improved gate control is found to counteract the deterioration due to confinement. [ABSTRACT FROM AUTHOR]

Due to the complexity of impact-induced reaction, it is difficult to predict and evaluate the ignition and safety of explosives under low velocity impact. Plastic deformation is very important to explosive ignition under impact loading. At low strain rates, plastic deformation can be treated as an isothermal process. The deformation under high-strain-rate is usually seen as an adiabatic process, and the deformation work is transformed into heat with the attendant temperature increase of the explosive. In this paper, we proposed an ignition criterion in terms of effective plastic work and specific plastic power to predict the ignition of explosives under low velocity impact. The plastic work begins to accumulate, when the specific plastic power (i.e., the plastic strain rate) in a local region meets a threshold value; and when the plastic work is sufficient enough, the ignition occurs. The criterion parameters are determined by numerical simulation using LS-DYNA. Numerical simulation is compared with experimental data in order to calibrate the numerical model. The threshold values of this ignition criterion for different configurations are determined. In order to evaluate the validity of the criterion, the predictions of the ignition time, ignition zone, threshold velocities in Steven test with different PBX size designs and various projectiles, as well as the ignition threshold conditions in a modified drop weight test, Susan test, and Spigot test, are carried out. The predicted results show a good agreement with experimental results, and the errors of the ignition threshold are less than 15% for all the experimental configurations. [ABSTRACT FROM AUTHOR]

We consider a uniformly magnetized particle (i.e., a macroscopic magnetic moment) with an easy axis anisotropy. The particle's moment is switched from 'up' to 'down' direction by an external magnetic field applied parallel to the easy axis and continuously swept from a positive to a negative value. In addition, a small constant perpendicular bias field is present. It is shown that while the driving field switches the particle's moment in a conventional damped way, the perpendicular field creates an admixture of the precessional (ballistic) switching that speeds up the switching process. Precessional contribution produces a non-monotonic dependence of the switching time on the field sweep time with a minimum at a particular sweep time value. We derive analytic expressions for the optimal point, and for the entire dependence of the switching time on the field sweep time. Our approximation is valid in a wide parameter range and can be used to engineer and optimize of the magnetic memory devices. [ABSTRACT FROM AUTHOR]

The transmission coefficient and the ballistic conductance are studied theoretically for a Dirac fermion through the graphene periodic magnetic barriers modulated by a homogeneous in-plane electric field. The transmission is highly asymmetric for zero and low biased conditions of the system. In contrast, it turns out to be symmetric in case of strongly modulated (by electric field) magnetic barriers and becomes independent of the number of barriers due to the predominant Klein tunneling effect. Interesting electric field effects are noted on the angular transmission properties of the chiral carriers. The conductivity profile exhibits some negative differential conducting regions, the number and the sharpness of the regions being intimately related to the number of barriers and the Fermi energy of the system. [ABSTRACT FROM AUTHOR]

In this paper, we study the influences of a channel source-end potential profile on the ballistic transport of carriers in Si metal oxide semiconductor field effect transistors (MOSFETs) based on a quantum-corrected Monte Carlo device simulation. As a result, we found that higher ballistic efficiency is expected in MOSFETs with a heterojunction bottleneck barrier, such as Schottky source/drain MOSFETs, compared to that with the conventional p-n junction source and drain. Such a superior ballistic behavior is demonstrated due to the narrower bottleneck potential profile formed at the source-channel interface. [ABSTRACT FROM AUTHOR]

With the atomistic Kubo–Verges method we calculate the ballistic conductance of various conformers of DNA (A,B,Z), as well as intermediate and composite conformations, using experimental structures and model complexes. For duplexes with 6 and 15 base pairs, we find that the valence band conductivity near the Fermi edge varies dramatically between the different conformations, most notably for the B-to-Z transition. The latter conductivity differences are largely unchanged both in the presence and in the absence of trimethylthiol linkers between DNA and gold electrodes in vacuo, but become much less drastic when explicit molecular dynamics and water-counterion surrounding of B- and Z-DNA are taken into account. Based on atomistic structural models, we argue that changes in the electrostatic energy in the presence of an applied external electric field can induce conformational switching that may be exploited in novel DNA-based memory devices of high packing density. [ABSTRACT FROM AUTHOR]

We characterize the linear and nonlinear electron transport in quantum point contacts (QPCs) realized by a hybrid combination of etching and gating. We demonstrate that the strong electron confinement generated through this hybrid QPC process results in quantized subbands with a large energy separation, leading to the observation of robust one-dimensional quantum-transport effects. Measurements of the nonlinear differential conductance reveal an unexpected bunching of curves at 0.20-0.25×2e2/h, rather than at the expected value of 0.5×2e2/h. Application of a simple analytical model indicates that this bunching is associated with the highly asymmetric manner in which the source-drain voltage is dropped across the QPC near pinch-off and under nonequilibrium conditions. [ABSTRACT FROM AUTHOR]

This article presents a metamaterial for ballistic electrons, which consists of a quantum barrier formed in a semiconductor with negative effective electron mass. This barrier is the analog of a metamaterial for electromagnetic waves in media with negative electrical permittivity and magnetic permeability. Besides applications similar to those of optical metamaterials, a nanosized slab of a metamaterial for ballistic electrons, sandwiched between quantum wells of positive effective mass materials, reveals unexpected conduction properties, e.g., single or multiple room temperature negative differential conductance regions at very low voltages and with considerable peak-to-valley ratios, while the traversal time of ballistic electrons can be tuned to larger or smaller values than in the absence of the metamaterial slab. Thus, slow and fast electrons, analogous to slow and fast light, occur in metamaterials for ballistic electrons. [ABSTRACT FROM AUTHOR]

A fiber-optic confocal sensor for noncontact ballistic measurements is described. Determination of motion at velocities of 1.7 km/s with an uncertainty as small as ±0.3% is demonstrated for both a projectile and a free-surface target. The fibers detect the passage of the object at their conjugate image points created by low F/# optics. This results in an output signal comprising a train of sharp pulses each precisely identifying when the ballistic object traverses an image point. Since the ballistic object does not contact the sensor at the time of imaging, the measurements do not perturb the motion, enabling multi-fragment measurement, as well as repetitive measurements of the same object point. [ABSTRACT FROM AUTHOR]

The response of a ballistic mesoscopic Hall bar to a local potential barrier is investigated in the presence of an external magnetic field. The effect of the position of the local potential probe in the Hall cross on the Hall and bend resistance is investigated leading to two-dimensional (2D) resistance maps. The Onsager–Casimir symmetry relations and symmetry relations between resistance measurements when interchanging the current and voltage leads, is obtained numerically for such 2D resistance maps. Symmetry properties are derived for the Hall and bend resistance maps with respect to the position of the local potential barrier. [ABSTRACT FROM AUTHOR]

Nanoporous and microporous materials made from aligned cylindrical pores play important roles in present technologies and will play even bigger roles in future technologies. The insight into the phonon thermal conductivity of these materials is important and relevant in many technologies and applications. Since the mean free path of phonons can be comparable to the pore size and interpore distance, diffusion-approximation based effective medium models cannot be used to predict the thermal conductivity of these materials. Strictly speaking, the Boltzmann transport equation (BTE) must be solved to capture the ballistic nature of thermal transport; however, solving BTE in such a complex network of pores is impractical. As an alternative, we propose an approximate ballistic-diffusive microscopic effective medium model for predicting the thermal conductivity of phonons in two-dimensional nanoporous and microporous materials made from aligned cylindrical pores. The model captures the size effects due to the pore diameter and the interpore distance and reduces to diffusion-approximation based models for macroporous materials. The results are in good agreement with experimental data. [ABSTRACT FROM AUTHOR]

We have calculated the effect of the oxidation-induced strain on the ballistic conductance in a Si/SiO2 quantum point contact. The strain-induced deformation potential was calculated semiempirically using a viscoelastic continuum model. The charge carriers are confined to the corners of the waveguide by both the strain-induced deformation potential and the Si/SiO2 band edge discontinuity. As a consequence nearly degenerate symmetric and antisymmetric transverse states are formed for the Si [001] minima. This additional degeneracy within the Landauer-Büttiker formalism leads to doubling of conductance steps for electrons in the [001] minima which govern the conductance near the cutoff energy. Due to the additional strain-induced confinement, the effective channel width of the quantum point contact is smaller and therefore the conductance steps are sharper. [ABSTRACT FROM AUTHOR]

Pump–probe measurements of I2 in solid Ar are reported and analyzed to extract a description of cage response to impulsive excitation, from the gentle kick, up to the breaking point. The most informative data are obtained through wavepacket motion on cage-bound, but otherwise dissociative, potentials where the chromophore acts as a transducer to drive the cage and to report on the local dynamics. This general class of dynamics is identified and analyzed as a function of energy in Ar, Kr, and Xe. The overdriven cage rebounds with a characteristic period of 1.2 ps that shows little dependence on excitation amplitude in all hosts. After rebound, the cage rings as a local resonant mode in Ar, with a period of 1 ps and dephasing time of 3 ps. This mode remains at the Debye edge in Kr and Xe, with periods of 630 and 800 fs, and dephasing times of 8 and 6 ps, respectively. In the bound B-state, the cage fluctuates toward its dilated equilibrium structure on a time scale of 3 ps, which is extracted from the down-chirp in the molecular vibrational frequency. When kicked with excess energy of 4 eV, the Ar cage breaks with 50% probability, and the molecule dissociates. The kinetics of polarization selective, multiphoton dissociation with Gaussian laser intensity profiles is delineated and the ballistics of cage breakout is described: The photodissociation proceeds by destruction of the local lattice, by creating interstitials and vacancies. During large amplitude motion on cage-bound potentials, sudden, nonadiabatic spin–flip transitions can be observed and quantified in space and time. The spin–flip occurs with unit probability in Ar when the I*–I bond is stretched beyond 6 Å. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

We present an efficient method to calculate the ballistic transmission function and current of an arbitrarily shaped, multiterminal two- or three-dimensional open device. It is shown that the calculation of the energy dependent transmission function can be reduced to a single calculation of some stationary states of the isolated device and the inversion of a small matrix that is energy dependent. The size of this matrix is shown to be governed by the size of the boundary region between the leads and the device. The method that we term contact block reduction method is illustrated by a numerical example. [ABSTRACT FROM AUTHOR]

One of the most interesting problems of modern solid-state physics is the emission mechanism of bright photoluminescence in the red spectral range discovered in silicon nanocrystallite structures, particularly in wires and dots. This article presents an interpretation of strong "red" photoluminescence in silicon wires and dots based on hot carrier ballistic transport in the process of photoluminescence excitation. Photoluminescence (PL), its excitation, electron paramagnetic resonance, infrared absorption and Raman scattering spectra of as-prepared Si wires have been examined. Silicon wire layers (porous silicon) were obtained by electrochemical etching of p-type Si wafers in a HF-ethanol solution. An atomic force microscope is used for porous silicon morphology analysis. It is shown that the very low PL intensity could be attributed to carrier radiative recombination between localized states quantum confined inside Si nanocrystallites. It is revealed that the ballistic effect can enhance the effective hot carrier excitation of interface defect-related photoluminescence in Si nanocrystallite structures. PL excitation spectrum modification depending on the Si crystallite size confirms the role of the ballistic effect in PL excitation of Si low-dimensional structures. [ABSTRACT FROM AUTHOR]

Studies ballistic electronic transport in a proposed mesoscopic structure, quantum cable. Uniqueness of the structure quantum cable for the study of mesoscopic transport; Correlation between Fermi energy of electrons and ballistic conductance of quantum cable; Impact of the accidental degeneracies of the transverse subbands of quantum cable on the quantum conductance units.

Presents information on a study which examined the negative-effective-mass ballistic field-effect transistors. Ballistic carrier transport in diode structures; Ballistic carrier transport in gated structures; Numerical simulation procedure; Simulation results; Conclusions.

We report dynamic magnetotransport measurements in a ballistic quantum point contact (QPC) at gigahertz frequencies. We observed a gate-controlled crossover of the magnetoadmittance from the partially diffusive boundary scattering effect to weak localization. Moreover, the charge relaxation time of this mesoscopic circuit shows similar behaviors, indicating that the density of states of QPC channels is also sensitively adjusted by the boundary scattering in addition to their transmission. Our experiment demonstrates that boundary scattering plays a dominant role in the dynamic transport in a ballistic QPC and could influence the coherent dynamics in other QPC-based phase-coherent systems such as the quantum dots and qubits. [ABSTRACT FROM AUTHOR]

Examines the calculation of the current-voltage (I-V) characteristics within the ballistic limit involving the metal-oxide tunnel transistors (MOTT). What the gate transconductance improves; Discussion on the saturation (knee) point and three modes of current transport across the device; How the low-voltage current saturation for MOTT is obtained.

Discusses the influence of resonant multi-mode pumping has on a coherent far infrared field within a ballistic quantum channel. Characterizing of frequencies of the mode spectrum; Expectancy of the Rabi oscillations; How these oscillations are exploited.

Presents information discussing the space charge limited ballistic electron transport through double quantum well segments. Simulation of three different structures; How the anode currents in the structures oscillate; Increasing of the space charge.