Electron Heat Conduction Research Articles

Graphene: Diversified Flexible 2D Material for Wearable Vital Signs Monitoring

AbstractFlexible wearable sensors are expected to be the future generation of personal health monitoring devices with large‐area, multimodal, multipoint sensing, and complicated data analysis. However, multimaterial interfacial coalescence and mechanical matching critically challenge the advancement of flexible devices and multifunction integration. Graphene, with characteristic carbon sheet 2D material, is endowed with good transparency, stability, superior electron mobility, heat conductivity, excellent flexibility, and mechanical performance. A summary of the progresses of flexible graphene‐based sensors in terms of material processing, sensor configuration, and property is presented. Various assembly structures could perform different electrical behaviors with unitary graphene material. The diversity of graphene‐based temperature, humidity, pressure, strain, and integrated multifunctional sensors developed in recent years is detailed. Benefitting from the commendable flexible mechanical performance and high durability, flexible graphene‐based sensors promote practical applications in body temperature monitoring, voice recognition, pulse‐beating, motion, and respiration detection. Finally, future research following the development trends and challenges of integrated graphene‐based sensors to develop their potential in human health monitoring and human–machine interfaces are discussed.

Investigation of Hydrodynamic Properties of Hot Dense Plasma

Hydrodynamic properties of hot dense plasma bunch have been studied in terms of their application to the problem of inertial confinement fusion. The two-temperature hydrodynamic equations taking into account the electron heat conduction and kinetics of the charge composition are presented. The following model problems are considered: expansion of a plasma bunch in a vacuum, compression of the plasma by shock waves, interaction of the plasma bunch with a laser radiation and a beam of heavy ions. The some problems arising in the problem of inertial confinement fusion are analyzed on the basis of the developed numerical methods.

Wavelength dependence of laser plasma interaction related to shock ignition approach

AbstractThis paper provides a summary of recent research connected with the shock ignition (SI) concept of the inertial confinement fusion which was carried out at PALS. In the experiments, Cu planar targets coated with a thin CH layer were used. Two-beam irradiation experiment was applied to investigate the effect of preliminary produced plasma to shock-wave generation. The 1ω or 3ω main beam with a high intensity >1015W/cm2generates shock wave, while the other 1ω beam with the intensity below 1014W/cm2creates CH pre-plasma simulating the pre-compressed plasma related to SI. Influence of laser wavelength on absorbed energy transfer to shock wave was studied by means of femtosecond interferometry and measuring the crater volume. To characterize the hot electron and ion emission, two-dimensional (2D) Kα-imaging of Cu plasma and grid collector measurements were used. In single 1ω beam experiments energy transport by fast electrons produced by resonant absorption made a significant contribution to shock-wave pressure. However, two-beam experiments with 1ω main beam show that the pre-plasma is strongly degrading the scalelength which leads to decreasing the fast electron energy contribution to shock pressure. In both the single 3ω beam experiments and the two-beam experiments with the 3ω main beam, do not show any clear influence of fast electron transport on shock-wave pressure. The non-monotonic behavior of the scalelength at changing the laser beam focal radius in both presence and absence of pre-plasma reflects the competition of plasma motion and electron heat conduction under the conditions of one-dimensional and 2D plasma expansion at large and small focal radii, respectively.

Multiscale Investigation of Femtosecond Laser Pulses Processing Aluminum in Burst Mode

ABSTRACTMegahertz is the highest femtosecond laser repetition rate that the state-of-the art technology can achieve. In this article, a single femtosecond laser pulse is burst into multiple femtosecond laser pulses to process aluminum. The temporal gap between two consecutive burst pulses is 2 picoseconds, which is much shorter than the temporal gap between two consecutive pulses at the repetition rate of megahertz. By taking the thermophysical scenarios of femtosecond laser induced of electron thermalization, electron heat conduction, electron–phonon-coupled heat transfer and atomic motion into account, a multiscale framework integrating ab initio quantum mechanical calculation, molecular dynamics and two-temperature model are constructed. The effect of femtosecond laser pulse number on the incubation phenomenon is studied. Comparing with the single pulse-processing aluminum film, the femtosecond laser in burst mode leads to smaller thermal stress, which is favorable to reduce the thermal mechanical damage of the material beneath the laser-irradiated surface. Appreciable differences among the simulation results by using electron thermophysical parameters from ab initio quantum mechanical calculation and those from experimental measurement, empirical estimation and calculation are found, indicating the essentials to precisely model the electron thermal response subject to femtosecond laser excitation.

A platform for x-ray Thomson scattering measurements of radiation hydrodynamics experiments on the NIF.

We present an experimental design for a radiation hydrodynamics experiment at the National Ignition Facility that measures the electron temperature of a shocked region using the x-ray Thomson scattering technique. Previous National Ignition Facility experiments indicate a reduction in Rayleigh-Taylor instability growth due to high energy fluxes, compared to the shocked energy flux, from radiation and electron heat conduction. In order to better quantify the effects of these energy fluxes, we modified the previous experiment to allow for non-collective x-ray Thomson scattering to measure the electron temperature. Photometric calculations combined with synthetic scattering spectra demonstrate an estimated noise.

Generation of keV hot near-solid density plasma states at high contrast laser-matter interaction

We present experimental evidence of ultra-high energy density plasma states with the keV bulk electron temperatures and near-solid electron densities generated during the interaction of high contrast, relativistically intense laser pulses with planar metallic foils. Experiments were carried out with the Ti:Sapphire laser system where a picosecond pre-pulse was strongly reduced by the conversion of the fundamental laser frequency into 2ω. A complex diagnostics setup was used for evaluation of the electron energy distribution in a wide energy range. The bulk electron temperature and density have been measured using x-ray spectroscopy tools; the temperature of supra-thermal electrons traversing the target was determined from measured bremsstrahlung spectra; run-away electrons were detected using magnet spectrometers. Analysis of the bremsstrahlung spectra and results on measurements of the run-away electrons showed a suppression of the hot electron production in the case of the high laser contrast. Characteristic x-ray radiation has been used for evaluation of the bulk electron temperature and density. The measured Ti line radiation was simulated both in steady-state and transient approaches using the code FLYCHK that accounts for the atomic multi-level population kinetics. The best agreement between the measured and the synthetic spectrum of Ti was achieved at 1.8 keV electron temperature and 2 × 1023 cm−3 electron density. By application of Ti-foils covered with nm-thin Fe-layers, we have demonstrated that the thickness of the created keV hot dense plasma does not exceed 150 nm. Results of the pilot hydro-dynamic simulations that are based on a wide-range two-temperature Equation of States, wide-range description of all transport and optical properties, ionization, electron, and radiative heating, plasma expansion, and Maxwell equations (with a wide-range permittivity) for description of the laser absorption are in excellent agreement with experimental results. According to these simulations, the generation of keV-hot bulk electrons is caused by the collisional mechanism of the laser pulse absorption in plasmas with a near solid step-like electron density profile. The laser energy, first deposited into the nm-thin skin-layer, is then transported into 150 nm depth by the electron heat conductivity. This scenario is opposite to the volumetric character of the energy deposition produced by supra-thermal electrons.

Martian Electron Temperatures in the Subsolar Region: MAVEN Observations Compared to a One‐Dimensional Model

AbstractPrior to the Mars Atmospheric Volatile EvolutioN (MAVEN) mission, altitude profiles of the electron temperature in the Martian thermosphere were measured only twice. Because the rates of several geophysically important processes depend strongly on the electron temperature, models of the Martian thermosphere and atmospheric escape rates have not been well constrained. In this paper, we use densities and temperatures measured by MAVEN instruments and the one‐dimensional model of Matta et al. (2014, https://doi.org/10.1016/j.icarus.2013.09.006) to test our understanding of the processes that determine the electron temperature. Our analysis is limited to inbound orbits where the magnetic field is within 30° of horizontal and the satellite is within 30° of the subsolar point at altitudes from 120 to 250 km. We introduce empirically adjusted electron temperatures below 180 km, where the MAVEN electron temperature measurements are known to be biased high. We introduce the concept of a local electron heating efficiency, which we define at a given altitude as the ratio of electron heating from photoionization to the total extreme ultraviolet energy deposited. Our analysis shows that MAVEN observations are consistent with the one‐dimensional model below ~210 km if the electron heating efficiency varies with altitude, and the electron temperature is within the empirical bounds below 180 km we introduced. It indicates that above ~210 km electron heat conduction dominates extreme ultraviolet heating in determining electron temperature. Our analysis also suggests that in the subsolar region electrons and neutrals are in thermal equilibrium below 120 km.

Ablation enhancement of metal in ultrashort double-pulse experiments

We report an ablation enhancement (both deepening and widening in ablation profiles) on nickel by ultrashort double-pulse laser irradiation, an exception of the typical reduction trend observed in ablation rates for metals irradiated with double-pulse excitations. Maximized at a pulse-separation (τs) of approximately 4 ps, the enhancement was observed before τs was increased to approximately the electron-lattice energy relaxation time. An achievement of ablation, by temporal shaping a weak pulse with energy well below the single-pulse ablation threshold into two considerably weaker pulses, was demonstrated. It is proposed that the enhanced electron-phonon coupling and drop of electronic heat conductivity, both of which result from the reductions in electron temperature (by pulse shaping), co-contribute to the widening in ablation profiles, while the former one is responsible for the deepening. This letter proposed an ablation enhancement approach to ultrashort laser processing of nickel.

Laboratory Photoionization Fronts in Nitrogen Gas: A Numerical Feasibility and Parameter Study

Abstract Photoionization fronts play a dominant role in many astrophysical situations but remain difficult to achieve in a laboratory experiment. We present the results from a computational parameter study evaluating the feasibility of the photoionization experiment presented in the design paper by Drake et al. in which a photoionization front is generated in a nitrogen medium. The nitrogen gas density and the Planckian radiation temperature of the X-ray source define each simulation. Simulations modeled experiments in which the X-ray flux is generated by a laser-heated gold foil, suitable for experiments using many kJ of laser energy, and experiments in which the flux is generated by a “z-pinch” device, which implodes a cylindrical shell of conducting wires. The models are run using crash, our block-adaptive-mesh code for multimaterial radiation hydrodynamics. The radiative transfer model uses multigroup, flux-limited diffusion with 30 radiation groups. In addition, electron heat conduction is modeled using a single-group, flux-limited diffusion. In the theory, a photoionization front can exist only when the ratios of the electron recombination rate to the photoionization rate and the electron-impact ionization rate to the recombination rate lie in certain ranges. These ratios are computed for several ionization states of nitrogen. Photoionization fronts are found to exist for laser-driven models with moderate nitrogen densities (∼1021 cm−3) and radiation temperatures above 90 eV. For “z-pinch”-driven models, lower nitrogen densities are preferred (<1021 cm−3). We conclude that the proposed experiments are likely to generate photoionization fronts.

Laser ablation under different electron heat conduction models in inertial confinement fusion

In this paper, we study the influence of three different electron heat conduction models on the laser ablation of gold plane target. Different from previous studies, we concentrate on the plasma conditions, the conversion efficiency from laser into soft x rays and the scaling relation of mass ablation, which are relevant to hohlraum physics study in indirect drive inertial confinement fusion. We find that the simulated electron temperature in corona region is sensitive to the electron heat conduction models. For different electron heat conduction models, there are obvious differences in magnitude and spatial profile of electron temperature. For the flux limit model, the calculated conversion efficiency is sensitive to flux limiters. In the laser ablation of gold, most of the laser energies are converted into x rays. So the scaling relation of mass ablation rate is quite different from that of low Z materials.

GeV ion irradiation of NiFe and NiCo: Insights from MD simulations and experiments

Concentrated solid solution alloys have attracted rapidly increasing attention due to their potential for designing materials with high tolerance to radiation damage. To tackle the effects of chemical complexity in defect dynamics and radiation response, we present a computational study on swift heavy ion induced effects in Ni and equiatomic Ni -based alloys (Ni50Fe50, Ni50Co50) using two-temperature molecular dynamics simulations (2T-MD). The electronic heat conductivity in the two-temperature equations is parameterized from the results of first principles electronic structure calculations. A bismuth ion (1.542 GeV) is selected and single impact simulations performed in each target. We study the heat flow in the electronic subsystem and show that alloying Ni with Co or Fe reduces the heat dissipation from the impact by the electronic subsystem. Simulation results suggest no melting or residual damage in pure Ni while a cylindrical region melts along the ion propagation path in the alloys. In Ni50Co50 the damage consists of a dislocation loop structure (d = 2 nm) and isolated point defects, while in Ni50Fe50, a defect cluster (d = 4 nm) along the ion path is, in addition, formed. The simulation results are supported by atomic-level structural and defect characterizations in bismuth-irradiated Ni and Ni50Fe50. The significance of the 2T-MD model is demonstrated by comparing the results to those obtained with an instantaneous energy deposition model without consideration of e-ph interactions in pure Ni and by showing that it leads to a different qualitative behavior.

The ultraviolet photodetection properties of gallium nitride/ silicon nanoporous pillar array

The accurate detection of ultraviolet light (UV) has been playing important roles in a variety of fields such as industrial and agricultural production, environmental monitoring and protection, defense and aerospace industries. Semiconductor materials have been widely used in fabricating various photodectors. As a representative of the first generation semiconductor materials, silicon has been applied to fabricate UV photodetector for a long time. For example, the first solid UV detectors were based on UV-enhanced silicon photodiode. Nevertheless, silicon-based photodiodes usually exhibit responses to visible light, which will cause serious disturbances for the detection of UV. Furthermore, crystal silicon is an indirect bandgap semiconductor, which decides that its conversion efficiency and therefore responsivity during the optoelectronic process would be low. All these shortcomings make the effort on developing novel UV photodetectors being both important and necessary. In the past years, great progresses have been achieved in preparing high-quality compound semiconductors with direct and wide bandgaps, and this provides a good opportunity for developing high-performance UV photodectors. As a III-V compound semiconductor with a direct and wide bandgap (~3.4 eV), gallium nitride (GaN) possesses the properties of high electronic mobility and heat conductivity, good chemical and thermal stability, and excellent anti-irradiation capability, and therefore is thought to be one of the most suitable materials for preparing UV detectors. Currently, high-quality GaN thin films are usually prepared by heteroepitaxy technology utilizing sapphire wafers as substrates. However, sapphire is an insulator, which can be used only as a mechanical support instead of a functional substrate and might bring additional technical difficulty in device integration. Such a problem might be solved by using silicon substrate, provided that the large lattice and thermal mismatch between silicon and GaN can be conquered, or it will cause serious problems relating to the device performance and operation stability. A proved method is through introducing nanostructured silicon substrates to construct GaN/Si heterojunction, by which the mismatches could be greatly diminished through a three-dimensional stress release mode at the GaN and silicon interface. Silicon nanoporous pillar array (Si-NPA) is a silicon hierarchical structure characterized by a regular array of well separated, micron-sized and highly nanoporous silicon pillars, and it has been proved an ideal template for preparing silicon-based heterstructures with high-quality interfaces. Here we will report that utilizing Si-NPA as substrates, GaN/Si-NPA nanoheterojunctions were prepared by growing GaN nanocrystallites using a chemical vapor deposition method. Through changing the deposition time, the surface morphology, chemical constitution, and electrical and photoluminescent properties of GaN/Si-NPA can be tuned effectively, and this provided a solid foundation for optimizing the device performance of the subsequently developed UV photodetectors. Through preparing ITO top transparent electrodes and silver back electrodes on these nanoheterojunctions, prototype UV photodectors with a device structure of ITO/GaN/Si-NPA/ sc -Si/Ag were prepared and the photodetection properties were studied. It was shown that high-quality UV detection can be realized without applying any bias, with the response and recovery time being ~0.12 s and ~0.24 s, respectively. For the monochromatic UV light with a wavelength of 340 nm, a responsivity of ~0.15 mA/W was achieved. These results might have provided a novel route for developing Si-based GaN UV photodetectors.

One-step growth of graphene-carbon nanotube trees on 4″ substrate and characteristics of single individual tree

We develop a simple one-step growth method to obtain a novel kind of tree-like carbon nano composite structure on a 4″ stainless steel substrate, which is a nano graphene-carbon nanotube tree (GCT). The structures are synthesized by using a plasma enhanced chemical vapor deposition method. The GCT consists of few-layer graphenes (FLG) epitaxially growing from a carbon nanotube (CNT) and they can grow uniformly on a 4″ substrate. Analysis of chemical bonding between FLG and CNT is given. In addition, electron micrographs are presented to show how a tree grows. Finally, we also develop techniques to characterize both experimentally and theoretically the electrical conductivity, field electron emission, heat conduction and heat radiation of a GCT. The electrical conductivity of a GCT is compatible to high quality CNT, the current performance of field electron emission is significantly high compared to the other individual single nanostructure, and very outstanding heat radiation effect is found. We believe that this large-area GCTs film can find potential applications such as super capacitor, terahertz wave manipulation, heat dissipation and field electron emission.

Negligible Electronic Contribution to Heat Transfer across Intrinsic Metal/Graphene Interfaces

AbstractDespite the importance of high thermal conductance (G) of metal/graphene interfaces to thermal management of graphene devices, prior reported G of graphene interfaces is all relatively low. One possible route to improve G of metal/graphene interfaces is through additional heat conduction by electrons, since graphene can be easily doped by metals. In this study, we evaluate the electronic heat conduction across metal/graphene interfaces by measuring G of palladium (Pd)/transferred graphene (trG)/Pd interfaces, prepared by either thermal evaporation or magnetron sputtering. It is found that, for Pd/trG/Pd samples prepared by thermal evaporation, G = 42 MW m−2 K−1 and G only weakly depends on temperature, suggesting that heat is predominantly carried by phonons. However, for Pd/trG/Pd samples prepared by sputtering, a significant increment of G is observed. G = 300 MW m−2 K−1, and is roughly proportional to temperature. We attribute the enhancement of G to an additional channel of heat transport by electrons via atomic‐scale pinholes generated in the graphene by ion bombardment during magetron sputtering. Thus, it is concluded that electrons play a negligible role in heat conduction across intrinsic metal/graphene interfaces, and the contribution of electrons is only substantial if graphene is damaged.

Collisionality dependence and ion species effects on heat transport in He and H plasma, and the role of ion scale turbulence in LHD

Surveys of the ion and electron heat transports of neutral beam (NB) heating plasma were carried out by power balance analysis in He and H rich plasma at LHD. Collisionality was scanned by changing density and heating power. The characteristics of the transport vary depending on collisionality. In low collisionality, with low density and high heating power, an ion internal transport barrier (ITB) was formed. The ion heat conductivity (χi) is lower than electron heat conductivity (χe) in the core region at ρ < 0.7. On the other hand, in high collisionality, with high density and low heating power, χi is higher than χe across the entire range of plasma. These different confinement regimes are associated with different fluctuation characteristics. In ion ITB, fluctuation has a peak at ρ = 0.7, and in normal confinement, fluctuation has a peak at ρ = 1.0. The two confinement modes change gradually depending on the collisionality. Scans of concentration ratio between He and H were also performed. The ion confinement improvements were investigated using gyro-Bohm normalization, taking account of the effective mass and charge. The concentration ratio affected the normalized χi only in the edge region (ρ ~ 1.0). This indicates ion species effects vary depending on collisionality. Turbulence was modulated by the fast ion loss instability. The modulation of turbulence is higher in H rich than in He rich plasma.

The potential of imposed magnetic fields for enhancing ignition probability and fusion energy yield in indirect-drive inertial confinement fusion

We examine the potential that imposed magnetic fields of tens of Tesla that increase to greater than 10 kT (100 MGauss) under implosion compression may relax the conditions required for ignition and propagating burn in indirect-drive inertial confinement fusion (ICF) targets. This may allow the attainment of ignition, or at least significant fusion energy yields, in presently performing ICF targets on the National Ignition Facility (NIF) that today are sub-marginal for thermonuclear burn through adverse hydrodynamic conditions at stagnation [Doeppner et al., Phys. Rev. Lett. 115, 055001 (2015)]. Results of detailed two-dimensional radiation-hydrodynamic-burn simulations applied to NIF capsule implosions with low-mode shape perturbations and residual kinetic energy loss indicate that such compressed fields may increase the probability for ignition through range reduction of fusion alpha particles, suppression of electron heat conduction, and potential stabilization of higher-mode Rayleigh-Taylor instabilities. Optimum initial applied fields are found to be around 50 T. Given that the full plasma structure at capsule stagnation may be governed by three-dimensional resistive magneto-hydrodynamics, the formation of closed magnetic field lines might further augment ignition prospects. Experiments are now required to further assess the potential of applied magnetic fields to ICF ignition and burn on NIF.

Simulation of self-generated magnetic fields in an inertial fusion hohlraum environment

We present radiation-hydrodynamic simulations of self-generated magnetic field in a hohlraum, which show an increased temperature in large regions of the underdense fill. Non-parallel gradients in electron density and temperature in a laser-heated plasma give rise to a self-generated field by the “Biermann battery” mechanism. Here, HYDRA simulations of three hohlraum designs on the National Ignition Facility are reported, which use a partial magnetohydrodynamic (MHD) description that includes the self-generated source term, resistive dissipation, and advection of the field due to both the plasma flow and the Nernst term. Anisotropic electron heat conduction parallel and perpendicular to the field is included, but not the Righi-Leduc heat flux. The field strength is too small to compete significantly with plasma pressure, but affects plasma conditions by reducing electron heat conduction perpendicular to the field. Significant reductions in heat flux can occur, especially for high Z plasma, at modest values of the Hall parameter, Ωeτei≲1, where Ωe=eB/mec and τei is the electron-ion collision time. The inclusion of MHD in the simulations leads to 1 keV hotter electron temperatures in the laser entrance hole and high-Z wall blowoff, which reduces inverse-bremsstrahlung absorption of the laser beam. This improves propagation of the inner beams pointed at the hohlraum equator, resulting in a symmetry shift of the resulting capsule implosion towards a more prolate shape. The time of peak x-ray production in the capsule shifts later by only 70 ps (within experimental uncertainty), but a decomposition of the hotspot shape into Legendre moments indicates a shift of P2/P0 by ∼20%. This indicates that MHD cannot explain why simulated x-ray drive exceeds measured levels, but may be partially responsible for failures to correctly model the symmetry.

CHROMOSPHERE TO 1 au SIMULATION OF THE 2011 MARCH 7th EVENT: A COMPREHENSIVE STUDY OF CORONAL MASS EJECTION PROPAGATION

ABSTRACT We perform and analyze the results of a global magnetohydrodynamic simulation of the fast coronal mass ejection (CME) that occurred on 2011 March 7. The simulation is made using the newly developed Alfvén Wave Solar Model (AWSoM), which describes the background solar wind starting from the upper chromosphere and extends to 24 R ⊙. Coupling AWSoM to an inner heliosphere model with the Space Weather Modeling Framework extends the total domain beyond the orbit of Earth. Physical processes included in the model are multi-species thermodynamics, electron heat conduction (both collisional and collisionless formulations), optically thin radiative cooling, and Alfvén-wave turbulence that accelerates and heats the solar wind. The Alfvén-wave description is physically self-consistent, including non-Wentzel–Kramers–Brillouin reflection and physics-based apportioning of turbulent dissipative heating to both electrons and protons. Within this model, we initiate the CME by using the Gibson-Low analytical flux rope model and follow its evolution for days, in which time it propagates beyond STEREO A. A detailed comparison study is performed using remote as well as in situ observations. Although the flux rope structure is not compared directly due to lack of relevant ejecta observation at 1 au in this event, our results show that the new model can reproduce many of the observed features near the Sun (e.g., CME-driven extreme ultraviolet [EUV] waves, deflection of the flux rope from the coronal hole, “double-front” in the white light images) and in the heliosphere (e.g., shock propagation direction, shock properties at STEREO A).

Physical properties of the quiet solar chromosphere–corona transition region

The physical properties of the quiet solar chromosphere–corona transition region are studied. Here the structure of the solar atmosphere is governed by the interaction of magnetic fields above the photosphere. Magnetic fields are concentrated into thin tubes inside which the field strength is great. We have studied how the plasma temperature, density, and velocity distributions change along a magnetic tube with one end in the chromosphere and the other one in the corona, depend on the plasma velocity at the chromospheric boundary of the transition region. Two limiting cases are considered: horizontally and vertically oriented magnetic tubes. For various plasma densities we have determined the ranges of plasma velocities at the chromospheric boundary of the transition region for which no shock waves arise in the transition region. The downward plasma flows at the base of the transition region are shown to be most favorable for the excitation of shock waves in it. For all the considered variants of the transition region we show that the thermal energy transfer along magnetic tubes can be well described in the approximation of classical collisional electron heat conduction up to very high velocities at its base. The calculated extreme ultraviolet (EUV) emission agrees well with the present-day space observations of the Sun.

Melting of aluminum with ideal or defect lattice: Molecular dynamics simulations with accounting of electronic heat conductivity

In this work, the atomistic simulations of rapid melting of aluminum are performed. We use the two-temperature approach separately describing the ionic and electronic subsystems of crystal. Both ideal and defect states of initial lattice are considered. The dependence of melting temperature on pressure is investigated in the simulations of thermal equilibrium establishment in the systems with plate interphase boundaries. Non-equilibrium melting of aluminum is studied in simulations with the constant rate of heat energy supply. The maximal temperatures of overheated material before complete melting are obtained in dependence of energy supply rate. Presence of initial defects of lattice substantially decreases the overheating of material. Electronic heat conductivity significantly accelerates the thermal equilibrium establishment in systems with interphase boundaries and decreases the drop of temperature after beginning of melting in the systems with constant rate of heating.