Energy Release Values Research Articles

Simulation of Gas-Dynamic and Thermal Processes in Vortex-Stabilized, Inductively Coupled Argon–Hydrogen Plasma

The flow of vortex-stabilized argon–hydrogen plasma in a radiofrequency induction (RFI) plasma torch has been investigated using modern methods of computational fluid dynamics. Optimal values of the torch power and energy release in plasma have been found at various argon to hydrogen ratios in the plasma gas mixture. The heat and kinetic fields determined by calculation for a plasma-chemical reactor can be of use in designing an RFI plasma torch in part concerning the determination of the optimum zone for feeding the reactants to the reactor.

A new energy index for evaluating the tendency of rockburst and its engineering application

Based on energy-transfer analysis of triaxial unloading tests under four different controlling conditions, the rock burst energy release rate (RBERR)-an energy index combining the local energy release rate (LERR) and the limit energy storage rate (LESR), was proposed. LERR refers to the values of the elastic strain energy release of an element after brittle failure, which indicates that RBERR>0 can be used to determine whether the element belongs to an excavation damage zone. RBERR was implemented to simulate the evolution process of rock damage and failure with advancing excavation face. The results predicted using RBERR were consistent with those obtained from an actual rockburst. In addition, a synthesis method based on microseismic (MS) monitoring information and RBERR simulation analysis was implemented for the Huainan coal mine. A study on the spatial- temporal evolutional laws of MS events built relationships between MS monitoring information and excavation process and; consequently, the potential danger areas of rockburst were determined. RBERR was used to analyze the location and intensity of rockburst in potential danger areas, which could be valuable in the design of rockburst- resistant measures in deep- buried construction.

MODELLING THE ENERGY RELEASE PROCESS OF AFTERSHOCKS

A stochastic model for the study of Benioff strain release during aftershock sequences is suggested. The stochastic model is elaborated after a compound Poisson process and is applied on data of the M7.1 Ocober 18, 1989 Loma Prieta aftershock sequence in northern California, USA. The temporal evolution of the number of events is first modelled by the Restricted Epidemic Type Aftershock Sequence (RETAS) model and then the identified best fit model is incorporated in the energy release analysis. The suggested model is based on the assumptions that there is no relation between the magnitude and the occurrence time of an event first and second, that there is no relation between the magnitude of a certain event and magnitudes of previous events. The obtained results from the examination of the energy release reveal that the suggested model makes a good fit of the aftershock Benioff strain release and enables a more detailed study by identifying possible deviations between data and model. The real cumulative energy release values surpass the expected model ones, which proves that aftershocks, stronger than forecasted by the model, are clustered at the beginning of the Loma Prieta sequence.

Propagation of gaseous detonation waves in a spatially inhomogeneous reactive medium

Detonation propagation in a compressible medium wherein the energy release has been made spatially inhomogeneous is examined via numerical simulation. The inhomogeneity is introduced via step functions in the reaction progress variable, with the local value of energy release correspondingly increased so as to maintain the same average energy density in the medium, and thus a constant Chapman Jouguet (CJ) detonation velocity. A one-step Arrhenius rate governs the rate of energy release in the reactive zones. The resulting dynamics of a detonation propagating in such systems with one-dimensional layers and two-dimensional squares are simulated using a Godunov-type finite-volume scheme. The resulting wave dynamics are analyzed by computing the average wave velocity and one-dimensional averaged wave structure. In the case of sufficiently inhomogeneous media wherein the spacing between reactive zones is greater than the inherent reaction zone length, average wave speeds significantly greater than the corresponding CJ speed of the homogenized medium are obtained. If the shock transit time between reactive zones is less than the reaction time scale, then the classical CJ detonation velocity is recovered. The spatio-temporal averaged structure of the waves in these systems is analyzed via a Favre averaging technique, with terms associated with the thermal and mechanical fluctuations being explicitly computed. The analysis of the averaged wave structure identifies the super-CJ detonations as weak detonations owing to the existence of mechanical non-equilibrium at the effective sonic point embedded within the wave structure. The correspondence of the super-CJ behavior identified in this study with real detonation phenomena that may be observed in experiments is discussed.

Thermo-chemical and energetic properties of layered nano-thermite composites

Thermochemical properties and microstructures of layered aluminum (Al) and iron oxide (Fe2O3) nano-thermite were investigated via thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) for developing a new type of metastable intermolecular composites (MIC). The nanoparticles of Al and Fe2O3 were dispersed in solution and deposited separately on stainless steel electrodes by means of the electrophoretic deposition (EPD) process. These nanoparticles were dispersed and deposited without any surfactant and additive, which eliminates potential contaminates in products. In order to produce layered structures, nanoparticles were deposited in a sequence which promotes effective bonding between two different types of nanoparticles. SEM images demonstrate a layered structure with the intimate contact between Al and Fe2O3. DSC data was collected to characterize the onset temperature and energy release per unit mass from the layered composites with different molar ratios of Al/Fe2O3. It is revealed, based on the consistent onset temperatures from different composites, that the ignition of Al and Fe2O3 layers is closely associated with oxygen which is produced from thermal decomposition of Fe2O3. In addition, the thickness of the reaction zone is restricted by the diffusion length of oxygen across the layer-to-layer interface, which results in a varying degree of reaction completion within the composite and subsequently the distinct energy release values per unit mass. The decomposition of Fe2O3 nanoparticles, diffusion path of oxygen and interfacial contact between Al and Fe2O3 layers are found to determine the energetic properties of layered thermite composites.

Radiation mechanisms and physical properties of the γ-ray narrow-line Seyfert 1 galaxies

Abstract We investigate the physical properties and radiation mechanisms of 11 states of five narrow-line Seyfert 1 (NLS1) galaxies detected by the Large Area Telescope on board Fermi through modeling the quasi-simultaneous multi-band observations. We obtain the best-fitting model parameters and their uncertainties for each state with the χ2-minimization procedure and discuss their implications on the characteristics of jet. Similar to blazars, their spectral energy distributions (SEDs) have a two-humped structure and their non-thermal emission can be modelled with the single-zone synchrotron + inverse Compton (IC) model. For all states, the GeV γ-rays may be contributed by the external Compton (EC) emission components. The observations of Fermi are mostly located at the declining stage of the EC humps. Text < 0.5 eV in all cases (Text is the characteristic temperature of external soft photons), suggesting that their radiation zones may be usually located outside of the broad line region (BLR) and the soft photons of Compton scattering mainly come from the dust torus. Compared with the bright Fermi blazars studied by Ghisellini et al. (2014, Nature, 515, 376), the Pjet (the power of the jets) of NLS1 galaxies detected by Fermi is similar to that of the flat spectrum radio quasars (FSRQs) but a little larger than that of the BL Lac objects (BL Lacs). However, a comparison of Pr (the powers of radiations) with the FSRQs and BL Lac objects shows that NLS1 galaxies’ Pr has values comparable to BL Lac objects but lower than FSRQs in spite of having similar Pjet values and the same energy carrier (the cold protons) as the FSRQs. Observations indicate that γ-NLS1 galaxies might have lower η (efficiency of gravitational energy release) values than GeV blazars.

Metastable decay of nitrogen clusters ions, and determination of the average kinetic energy release and binding energy values

We have carried out measurements on metastable fragmentation of mass selected nitrogen cluster ions, (N2)n+, which are produced by electron impact ionization of a neutral nitrogen cluster beam. We have derived binding energies for n=5–10, from the kinetic energy released in metastable decay reactions using finite heat bath theory. Our results are compared with other experimental results and with quantum chemical calculations.

High-energy electron transfer dissociation of protonated amino acids

High-energy electron transfer dissociation (HE-ETD) of singly protonated amino acids was investigated using charge inversion mass spectrometry with alkali metal targets in which dissociations of charge-reduced neutrals were induced from the excited neutral intermediates. The dominant trapezoidal peaks of the 17 u loss in the charge inversion spectra of the protonated aliphatic amino acids were assigned to NH3 loss caused by NCα bond cleavage from hypervalent ammonium radical intermediates via a repulsive state; this assignment was based on the peak shape and kinetic energy release (KER) values. The peak of the non-dissociated ion observed in the proline spectra was explained by the same bond cleavage. The triangular peaks of the 2 u loss, which were dominantly observed in all of the spectra, were assigned to H2 elimination, which involved H atom migration in the neutral radical. Neutral intermediates that induced the H2 loss were estimated to have a lower internal energy than that of the NH3 loss by comparing the charge inversion spectra of the different target atoms. Differences in the isobaric ions between leucine and isoleucine were found in the bond dissociation of CβCγ in their side chains following the NH3 loss and in the intensity of the NH3 loss relative to that of the H2 loss. The charge inversion spectra of the protonated amino acids, with side chains that are subject to post-translational modification, provided intense peaks resulting from the consecutive and competitive loss of neutral molecules following the NH3 loss and H2 loss. Along with these losses, side chain losses caused by H atom migration were also observed as sharp peaks with KER values smaller than that of the consecutive loss.

The Distinctive Features of Anticoincidence Detector System of the GAMMA-400 Gamma-ray Telescope

Some features of scintillation anticoincidence system (includes ACtop detector section located upper the converter-tracker and four AClat ones placed from its lateral sides) of the GАММА-400 gamma-ray telescope, related to joint operations with another fast scintillation systems: SDC (scintillation detector system of calorimeter) and TOF (time-of-flight system) are considered. The main problem for high-energy (over 50GeV) gamma-rays registration by gamma-telescopes is the presence of so-called «backsplash current» (BS) of particles from massive calorimeter when detecting of particles is provided. BS is a set of low energy particles, moving up from the calorimeter and producing triggering of the anticoincidence detectors, imitating detection of a charged particle. As an additional indicator of BS particles presence of in the ACtop detector, we offer the value of energy release in the S3 scintillation detector placing between two parts of the calorimeter (CC1 and CC2). Fast trigger signal in the main aperture for gamma-quanta is composed of analysis of TOF system signal, showing that charged particle or particles move in the direction from up to down, and ACtop energy deposition taking in to account specially designed for GAMMA-400 algorithms of backsplash rejection.

Three body dissociation of ${\rm CS}_2^{2+}$CS22+ subsequent to various S(2p) Auger transitions

Fragmentation kinematics of CS2 following various S(2p) Auger transitions is studied. Employing a combination of electron energy analysis and recoil ion momentum spectroscopy, changes in the dissociation channel yields, as well as the differences in the kinematical parameters for various bands of Auger hole states are presented. The fragmentation mechanism for dissociative channels leading to complete atomization of CS2(2+) molecular ion is studied in detail. We find that CS2(2+) does not retain linear geometry and is bent before undergoing concerted break-up. It is also observed that different geometric configurations of the CS2(2+) precursor result in different kinetic energy release values.

Characterization of thermochemical properties of Al nanoparticle and NiO nanowire composites

Thermochemical properties and microstructures of the composite of Al nanoparticles and NiO nanowires were characterized. The nanowires were synthesized using a hydrothermal method and were mixed with these nanoparticles by sonication. Electron microscopic images of these composites showed dispersed NiO nanowires decorated with Al nanoparticles. Thermal analysis suggests the influence of NiO mass ratio was insignificant with regard to the onset temperature of the observed thermite reaction, although energy release values changed dramatically with varying NiO ratios. Reaction products from the fuel-rich composites were found to include elemental Al and Ni, Al2O3, and AlNi. The production of the AlNi phase, confirmed by an ab initio molecular dynamics simulation, was associated with the formation of some metallic liquid spheres from the thermite reaction.

Primary containment capacity of Prototype Fast Breeder Reactor against core disruptive accident loadings

Severe accident analysis methodologies of sodium cooled fast reactors are critically re-looked in recent years and several scenarios are postulated. Development of advanced numerical and experimental techniques is carried out with the objective of determining realistic energy release, which is still evolving internationally. In view of this, a parametric study on mechanical energy release values in the range 100–1000MJ under a core disruptive accident condition, has been carried out for a 500MWe pool type Prototype Fast Breeder Reactor (PFBR) and associated mechanical consequences are assessed. The investigation focuses on issues related to structural integrity of primary containment, reactor containment building and post accident cooling capability. The assumptions made on estimation of mechanical energy release have been brought out with appropriate justifications. Fluid and structural dynamics analysis results are presented and discussed in detail depicting the loading sequences and various physical phenomena involved.The analysis carried out for PFBR indicates that primary containment has high potential to withstand the transient forces generated by energy release, corresponding to the work potential even more than 1000MJ. The sodium release to the reactor containment building through top shield penetrations under sodium slug impact phenomenon is limited with higher energy releases, mainly due to large dimensional changes of vessel associated with shorter transient duration and fall of sodium free level in the main vessel. The sodium level fall, a maximum value of 0.88m for 1000MJ is found to be acceptable for the PFBR. Hence, high uncertainties in the energy release estimation are not of great concern in PFBR safety studies. However, the deformations of decay heat exchangers immersed in the sodium pool could limit the acceptable work potential to 500MJ derived based on a separate experimental study.

Fragmentation and kinetic energy release distribution of ions produced from methanol CH3OH

A double focusing mass spectrometer of reversed Nier-Johnson geometry was used in a research of ionization and fragmentation processes induced by the collision of methanol molecules CH3OH with an energetic electron beam. Two observed metastable fragmentation reactions were studied: decay of the molecular parent ion CH3OH+ into CHOH+ and neutral 2H, and decay of the fragment ion CH3+ into CH2+ and neutral hydrogen. For these reactions the mean values of the kinetic energy release were calculated using MIKE (Mass-Analyzed Ion Kinetic Energy) technique and the KERD (Kinetic Energy Release Distribution) were determined. We obtain the < Ɛ > values of 16 meV and 52 meV for CHOH+ and CH2+ ions, respectively. We suggest a metastable electronically-excited state as a reason for the CH3+ fragmentation reactions.

UNIFYING THE ZOO OF JET-DRIVEN STELLAR EXPLOSIONS

We present a set of numerical simulations of stellar explosions induced by relativistic jets emanating from a central engine sitting at the center of compact, dying stars. We explore a wide range of durations of the central engine activity, two candidate stellar progenitors, and two possible values of the total energy release. We find that even if the jets are narrowly collimated, their interaction with the star unbinds the stellar material, producing a stellar explosion. We also find that the outcome of the explosion can be very different depending on the duration of the engine activity. Only the longest-lasting engines result in successful gamma-ray bursts. Engines that power jets only for a short time result in relativistic supernova explosions, akin to observed engine-driven SNe such as SN2009bb. Engines with intermediate durations produce weak gamma-ray bursts, with properties similar to nearby bursts such as GRB 980425. Finally, we find that the engines with the shortest durations, if they exist in nature, produce stellar explosions that lack sizable amounts of relativistic ejecta and are therefore dynamically indistinguishable from ordinary core-collapse supernovae.

Formation, structure, and dissociation dynamics of CO2q+(q≤3) ions due to impact of 12-keV electrons

The electron-impact multiple ionization and subsequent dissociation of CO${}_{2}$ is studied for 12-keV electron energy using a linear time-of-flight mass spectrometer coupled with a multihit, position-sensitive detector. The complete as well as incomplete Coulomb explosion pathways for CO${}_{2}$${}^{2+}$ and CO${}_{2}$${}^{3+}$ ions are examined and identified. The kinetic energy release distributions for these precursor ions are obtained. The experimental kinetic energy release values for the complete Coulomb fragmentation channels are found to be overestimated by those calculated from the Coulomb explosion model. From the angular correlation studies, it is inferred that bent geometrical states are involved for most of the fragmentation channels of CO${}_{2}$${}^{2+}$ and CO${}_{2}$${}^{3+}$ ions. The concerted and/or sequential nature of all the dissociation pathways is also assigned. This study provides the first results on energetics associated with the charge separation in dissociative ionization of CO${}_{2}$ under the impact of electrons at a subrelativistic energy.

Electronic Properties and Dissociative Photoionization of Thiocyanates. Part II. Valence and Shallow-Core (Sulfur and Chlorine 2p) Regions of Chloromethyl Thiocyanate, CH2ClSCN

A combination of photoelectron spectroscopy and synchrotron based photoelectron photoion coincidence (PEPICO) spectra has been applied to investigate the electronic structure and the dissociative ionization of the CH(2)ClSCN molecule in the valence region. The PES is assigned with the electronic structure calculations at the outer-valence Green's function and symmetry adapted cluster/configuration interaction (SAC-CI) levels offer an explanation of our experimental results. Upon vacuum ultraviolet irradiation the low-lying radical cation, located at 10.39 eV is formed. The molecular ion is observed in the time-of-flight mass spectra, together with the CH(2)SCN(+) and CH(2)Cl(+) daughter ions. The total ion yield spectra have been measured in the S 2p and Cl 2p regions and several channels have been determined in dissociative photoionization events for the core-excited species. Thus, by using time-of-flight mass spectrometry and synchrotron radiation the relative abundances of the ionic fragments and their kinetic energy release values were obtained from both PEPICO and photoelectron photoion photoion coincidence spectra. Possible fragmentation processes are discussed and compared with that found for the related CH(3)SCN species.

Auger decay of1σgand1σuhole states of theN2molecule: Disentangling decay routes from coincidence measurements

Results of the most sophisticated measurements in coincidence of the angular resolved K-shell photo- and Auger-electrons, and of two atomic ions produced by dissociation of N2 molecule, are analyzed. Detection of photoelectrons at certain angles allows separating the Auger decay processes of the 1{\sigma}g and 1{\sigma}u core hole states. The Auger electron angular distributions for each of these hole states are measured as a function of the kinetic energy release of two atomic ions and are compared with the corresponding theoretical angular distributions. From that comparison one can disentangle the contributions of different repulsive doubly charged molecular ion states to the Auger decay. Different kinetic energy release values are directly related to the different internuclear distances. In this way one can trace experimentally the behavior of the potential energy curves of dicationic final states inside the Frank-Condon region. Presentation of the Auger electron angular distributions as a function of kinetic energy release of two atomic ions opens a new dimension in the study of Auger decay.

Estimation of Explosion Energy Yield at Chernobyl NPP Accident

The value of the 133Xe/133mXe isometric activity ratio for the stationary regime of reactor work is about 35, and that for an instant fission (explosion) is about 11, which allowed estimation of the nuclear component of the instant (explosion) energy release during the NPP accident. Atmospheric xenon samples were taken at the trajectory of accident product transfers (in the Cherepovetz area); these samples were measured by a gamma spectrometer, and the 133Xe/133mXe ratio was determined as an average value of 22.4. For estimations a mathematic model was elaborated considering both the value of instant released energy and the schedule of reactor power change before the accident, as well as different fractionation conditions on the isobaric chain. Comparison of estimated results with the experimental data showed the value of the instant specific energy release in the Chernobyl NPP accident to be 2·105–2·106 J/Wt or 6·1014–6·1015 J (100–1,000 kt). This result is matched up to a total reactor power of 3,200 MWt. However this estimate is not comparable with the actual explosion scale estimated as 10t TNT. This suggests a local character of the instant nuclear energy release and makes it possible to estimate the mass of fuel involved in this explosion process to be from 0.01 to 0.1% of total quantity.

Seismogenic Shear Zones in the Lithospheric Mantle: Ultramafic Pseudotachylytes in the Lanzo Peridotite (Western Alps, NW Italy)

At Mt. Moncuni (Lanzo Massif, Western Alps) plagioclase peridotites and early mid-ocean ridge basalt (MORB) gabbroic dykes are deformed by shear zones containing cataclastic bands and both fault-vein and injection-vein pseudotachylytes, which are crosscut by late MORB porphyritic dykes. Fault-vein pseudotachylytes have thicknesses of the order of 1 mm; injection-vein pseudotachylytes have a typical thickness of 1–10 cm and contain spinifex textures. Structural, petrological and geochemical data show that the pseudotachylytes formed by near-complete melting of the host peridotite, at ambient temperature–pressure conditions (T = 600 ± 100°C, P < 0·5 GPa) close to the brittle–ductile transition of ultramafic rocks, during exhumation of the lithospheric mantle in the early stages of formation of the Ligurian Tethys oceanic basin. Estimates of the average volume fraction of unmelted clasts and of the ambient and liquidus temperature, together with thermophysical parameters, allow the determination of the melting energy per unit volume. Coseismic displacement is not observable at Mt. Moncuni, and consequently the dynamic shear resistance cannot be inferred. We show that commonly proposed relations between fault-vein thickness and displacement are of limited value, given the difficulty in identifying ‘single-event’ pseudotachylytes and the mobility of the melt. However, we also show that dynamic shear resistance can be predicted to decrease sharply if the melt coats the whole fault plane, partly as a consequence of the nonlinear viscosity of silicate melts at high strain rates. The Mt. Moncuni pseudotachylytes are the result of upper mantle seismicity at shallow depth (z < 20 km) over a time period of at most 5 Myr. Estimation of the total seismic energy release and moment (caused by an unspecified number of small to moderate earthquakes) requires an assessment of the total pseudotachylyte volume. This is highly uncertain, with a probable qualitative error margin of ±1 order of magnitude. The inferred values of cumulative seismic energy release and moment are of the order of 1015 ± 1 J and 1019 ± 1 N m, respectively, resulting in a seismic energy release rate of approximately 108 ± 1 J/a. This value is compatible with present-day seismic rates at extensional plate margins.

Perchloromethyl Mercaptan, CCl3SCl, Excited with Synchrotron Radiation in the Proximity of the Sulfur and Chlorine 2p Edges: Dissociative Photoionization of Highly Halogenated Species

We have investigated the dissociative photoionization of shallow-core excited CCl3SCl by using multicoincidence time-of-flight mass spectrometry and synchrotron radiation in the S 2p and Cl 2p edges. The relative abundances of the ionic fragments and their kinetic energy release values were obtained from both PEPICO (photoelectron photoion coincidence) and PEPIPICO (photoelectron photoion photoion coincidence) spectra. The dynamic of the ionic fragmentation of S and Cl 2p excited CCl3SCl has been studied and compared with those of CCl4. Features determined in the present study seem to be relevant aspects for explaining the dissociation of highly chlorinated species under the action of VUV irradiation. The fragmentation pattern shows that chlorine ion (Cl+) is prominently formed upon both S and Cl 2p excitations.