WorldWideScience

Sample records for hot electron component

  1. MIS hot electron devices for enhancement of surface reactivity by hot electrons

    DEFF Research Database (Denmark)

    Thomsen, Lasse Bjørchmar

    A Metal-Insulator-Semiconductor (MIS) based device is developed for investigation of hot electron enhanced chemistry. A model of the device is presented explaining the key concepts of the functionality and the character- istics. The MIS hot electron emitter is fabricated using cleanroom technology...... and the process sequence is described. An Ultra High Vacuum (UHV) setup is modified to facilitate experiments with electron emission from the MIS hot electron emitters and hot electron chemistry. Simulations show the importance of keeping tunnel barrier roughness to an absolute minimum. The tunnel oxide...... to be an important energy loss center for the electrons tunneling through the oxide lowering the emission e±ciency of a factor of 10 for a 1 nm Ti layer thickness. Electron emission is observed under ambient pressure conditions and in up to 2 bars of Ar. 2 bar Ar decrease the emission current by an order...

  2. Stabilizing effects of hot electrons on low frequency plasma drift waves

    International Nuclear Information System (INIS)

    Huang Chaosong; Qiu Lijian; Ren Zhaoxing

    1988-01-01

    The MHD equation is used to study the stabilization of low frequency drift waves driven by density gradient of plasma in a hot electron plasma. The dispersion relation is derived, and the stabilizing effects of hot electrons are discussed. The physical mechanism for hot electron stabilization of the low frequency plasma perturbations is charge uncovering due to the hot electron component, which depends only on α, the ratio of N h /N i , but not on the value of β h . The hot electrons can reduce the growth rate of the interchange mode and drift wave driven by the plasma, and suppress the enomalous plasma transport caused by the drift wave. Without including the effectof β h , the stabilization of the interchange mode requires α≅2%, and the stabilization of the drift wave requires α≅40%. The theoretical analyses predict that the drift wave is the most dangerous low frequency instability in the hot electron plasma

  3. Studies of instabilities and waves in a mirror confined hot electron plasma

    International Nuclear Information System (INIS)

    Huang Chaosong; Qiu Lijian; Ren Zhaoxing

    1989-01-01

    The stability of hot electron plasmas is studied. The hot electron component can stabilize the low frequency drift wave and the interchange mode driven by the plasma, which depends only on α=N h /N i , the density ratio of the hot electrons to the plasma ions, but not on the beta value and the annular structure of the hot electrons. Stabilization of the drift wave occurs for α > 40%, and that of the interchange mode for α > 5%, which allows the prediction that the interchange mode can be suppressed in hot electron plasma experiments. The experiments have been conducted in a simple mirror machine. It is observed that the plasma drives a drift wave at 40 kHz and an interchange mode at about 100 kHz. The fluctuation amplitude of the drift wave is much higher than that of the interchange mode. The hot electrons reduce the density gradient, the fluctuation amplitude and the radial loss of the plasma. On the other hand, the hot electrons drive the interchange mode and drift wave in the ion cyclotron frequency region. The effects of a cold plasma on hot electron perturbations are discussed. (author). 10 refs, 6 figs

  4. Nonlinear electron-acoustic rogue waves in electron-beam plasma system with non-thermal hot electrons

    Science.gov (United States)

    Elwakil, S. A.; El-hanbaly, A. M.; Elgarayh, A.; El-Shewy, E. K.; Kassem, A. I.

    2014-11-01

    The properties of nonlinear electron-acoustic rogue waves have been investigated in an unmagnetized collisionless four-component plasma system consisting of a cold electron fluid, non-thermal hot electrons obeying a non-thermal distribution, an electron beam and stationary ions. It is found that the basic set of fluid equations is reduced to a nonlinear Schrodinger equation. The dependence of rogue wave profiles on the electron beam and energetic population parameter are discussed. The results of the present investigation may be applicable in auroral zone plasma.

  5. Experimental study for angular distribution of the hot electrons generated by femtosecond laser interaction with solid targets

    International Nuclear Information System (INIS)

    Cai, D.F.; Gu, Y.Q.; Zheng, Z.J.; Wen, T.S.; Chunyu, S.T.; Wang, Z.B.; Yang, X.D.

    2003-01-01

    The experimental results of angular distribution of hot electrons in the interaction of a 60 fs, 125 mJ, 800 nm, ∼10 17 W cm -2 laser pulse with Al targets are reported. Three obvious peaks of hot electrons emission have been observed, as there is a weak normal component of the laser electric field. These emission peaks are located in the directions of the specular reflection of the laser, the target normal, and the backreflection of the laser, respectively. In the case of the P-polarized laser pulse, which has a strong normal component of the laser electric field, the peak in the backreflection of the laser disappeared, and only two obvious peaks of hot electron emissions existed. It shows that the different directions of hot electrons emission are dominated by different absorption or acceleration mechanisms. The experimental result of the hot electrons energy spectrum at the target normal shows that the effective temperature of hot electrons is about 190 keV, which is consistent with a scaling law of the resonance absorption

  6. X-rays diagnostics of the hot electron energy distribution in the intense laser interaction with metal targets

    Science.gov (United States)

    Kostenko, O. F.; Andreev, N. E.; Rosmej, O. N.

    2018-03-01

    A two-temperature hot electron energy distribution has been revealed by modeling of bremsstrahlung emission, measured by the radiation attenuation and half-shade methods, and Kα emission from a massive silver cylinder irradiated by a subpicosecond s-polarized laser pulse with a peak intensity of about 2 × 1019 W/cm2. To deduce parameters of the hot electron spectrum, we have developed semi-analytical models of generation and measurements of the x-rays. The models are based on analytical expressions and tabulated data on electron stopping power as well as cross-sections of generation and absorption of the x-rays. The Kα emission from thin silver foils deposited on low-Z substrates, both conducting and nonconducting, has been used to verify the developed models and obtained hot electron spectrum. The obtained temperatures of the colder and hotter electron components are in agreement with the values predicted by kinetic simulations of the cone-guided approach to fast ignition [Chrisman et al., Phys. Plasmas 15, 056309 (2008)]. The temperature of the low-energy component of the accelerated electron spectrum is well below the ponderomotive scaling and Beg's law. We have obtained relatively low conversion efficiency of laser energy into the energy of hot electrons propagating through the solid target of about 2%. It is demonstrated that the assumption about a single-temperature hot electron energy distribution with the slope temperature described by the ponderomotive scaling relationship, without detailed analysis of the hot electron spectrum, can lead to strong overestimation of the laser-to-electron energy-conversion efficiency, in particular, the conversion efficiency of laser energy into the high-temperature component of the hot electron distribution.

  7. Hot electron effects on the satellite spectrum of laser-produced plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Abdallah, J. [Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM (United States); Faenov, A.Y.; Pikuz, T.A. [MISDC, NPO ' VNIIFTRI' , Mendeleevo, Moscow Region, 141570 (Russian Federation); Wilke, M.D.; Kyrala, G.A.; Clark, R.E.H. [Los Alamos National Laboratory, PO Box 1663, Los Alamos, NM (United States)

    1999-05-01

    In laser-produced plasmas, the interaction of the intense laser light with plasma electrons can produce high-energy superthermal electrons with energies in the keV range. These hot electrons can influence the level populations which determine spectral line structure. In the present paper, the effect of hot electrons on the X-ray satellite spectrum of laser-produced plasmas is studied. Calculated spectra are compared with experimental observations. Magnesium targets irradiated by three different types of laser pulses are considered. These include, a high-intensity 600 fs Nd-glass laser, a 1 ns Nd-glass laser, and a 2ns CO{sub 2} laser. The Nd-glass laser experiments were conducted recently at the Los Alamos Trident Facility and the CO{sub 2} data were recorded by MISDC. High-resolution spectra were measured near the He-like resonance line of magnesium. The calculations employ an electron energy distribution which includes a thermal and a hot electron component, as part of a detailed collisional-radiative model. Plasma parameters including electron temperature, density, and hot electron fraction are estimated by choosing best fits to the experimental measurements. The calculations show that hot electrons can cause several anomalous effects. The Li-like jkl, abcd, and qr satellites can show intensities which are generally attributed to electron densities in excess of 10{sup 23} cm{sup -3}. In addition, the relative amplitude of the intercombination line can be unusually large even at high electron densities due to enhanced collisional excitation of the 1s2p{sup 3}P state by hot electrons. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

  8. Arbitrary amplitude fast electron-acoustic solitons in three-electron component space plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Mbuli, L. N.; Maharaj, S. K. [South African National Space Agency (SANSA) Space Science, P.O. Box 32, Hermanus 7200, Republic of South Africa (South Africa); Department of Physics, University of the Western Cape (UWC), Robert Sobukwe Road, Bellville 7535, Republic of South Africa (South Africa); Bharuthram, R. [Department of Physics, University of the Western Cape (UWC), Robert Sobukwe Road, Bellville 7535, Republic of South Africa (South Africa); Singh, S. V.; Lakhina, G. S. [Indian Institute of Geomagnetism, New Panvel (West), Navi Mumbai 410218 (India); Department of Physics, University of the Western Cape (UWC), Robert Sobukwe Road, Bellville 7535, Republic of South Africa (South Africa)

    2016-06-15

    We examine the characteristics of fast electron-acoustic solitons in a four-component unmagnetised plasma model consisting of cool, warm, and hot electrons, and cool ions. We retain the inertia and pressure for all the plasma species by assuming adiabatic fluid behaviour for all the species. By using the Sagdeev pseudo-potential technique, the allowable Mach number ranges for fast electron-acoustic solitary waves are explored and discussed. It is found that the cool and warm electron number densities determine the polarity switch of the fast electron-acoustic solitons which are limited by either the occurrence of fast electron-acoustic double layers or warm and hot electron number density becoming unreal. For the first time in the study of solitons, we report on the coexistence of fast electron-acoustic solitons, in addition to the regular fast electron-acoustic solitons and double layers in our multi-species plasma model. Our results are applied to the generation of broadband electrostatic noise in the dayside auroral region.

  9. Suppression of sawtooth oscillations due to hot electrons and hot ions

    International Nuclear Information System (INIS)

    Zhang, Y.Z.; Berk, H.L.

    1989-01-01

    The theory of m = 1 kink mode stabilization is discussed in the presence of either magnetically trapped hot electrons or hot ions. For instability hot ion requires particles peaked inside the q = 1 surface, while hot electrons require that its pressure profile be increasing at the q = 1 surface. Experimentally observed sawtooth stabilization usually occurs with off-axis heating with ECRH and near axis heating with ICRH. Such heating may produce the magnetically trapped hot particle pressure profiles that are consistent with theory. 17 refs., 2 figs

  10. Hot gas path component having near wall cooling features

    Science.gov (United States)

    Miranda, Carlos Miguel; Kottilingam, Srikanth Chandrudu; Lacy, Benjamin Paul

    2017-11-28

    A method for providing micro-channels in a hot gas path component includes forming a first micro-channel in an exterior surface of a substrate of the hot gas path component. A second micro-channel is formed in the exterior surface of the hot gas path component such that it is separated from the first micro-channel by a surface gap having a first width. The method also includes disposing a braze sheet onto the exterior surface of the hot gas path component such that the braze sheet covers at least of portion of the first and second micro-channels, and heating the braze sheet to bond it to at least a portion of the exterior surface of the hot gas path component.

  11. Surface-Plasmon-Driven Hot Electron Photochemistry.

    Science.gov (United States)

    Zhang, Yuchao; He, Shuai; Guo, Wenxiao; Hu, Yue; Huang, Jiawei; Mulcahy, Justin R; Wei, Wei David

    2017-11-30

    Visible-light-driven photochemistry has continued to attract heightened interest due to its capacity to efficiently harvest solar energy and its potential to solve the global energy crisis. Plasmonic nanostructures boast broadly tunable optical properties coupled with catalytically active surfaces that offer a unique opportunity for solar photochemistry. Resonant optical excitation of surface plasmons produces energetic hot electrons that can be collected to facilitate chemical reactions. This review sums up recent theoretical and experimental approaches for understanding the underlying photophysical processes in hot electron generation and discusses various electron-transfer models on both plasmonic metal nanostructures and plasmonic metal/semiconductor heterostructures. Following that are highlights of recent examples of plasmon-driven hot electron photochemical reactions within the context of both cases. The review concludes with a discussion about the remaining challenges in the field and future opportunities for addressing the low reaction efficiencies in hot-electron-induced photochemistry.

  12. Simulation studies on stability of hot electron plasma

    International Nuclear Information System (INIS)

    Ohsawa, Yukiharu

    1985-01-01

    Stability of a hot electron plasma in an NBT(EBT)-like geometry is studied by using a 2-1/2 dimensional relativistic, electromagnetic particle code. For the low-frequency hot electron interchange mode, comparison of the simulation results with the analytical predictions of linear stability theory show fairly good agreement with the magnitude of the growth rates calculated without hot electron finite Larmor radius effects. Strong stabilizing effects by finite Larmor radius of the hot electrons are observed for short wavelength modes. As for the high-frequency hot electron interchange mode, there is a discrepancy between the simulation results and the theory. The high-frequency instability is not observed though a parameter regime is chosen in which the high-frequency hot electron interchange mode is theoretically predicted to grow. Strong cross-field diffusion in a poloidal direction of the hot electrons might explain the stability. Each particle has a magnetic drift velocity, and the speed of the magnetic drift is proportional to the kinetic energy of each particle. Hence, if the particles have high temperature, the spread of the magnetic drift velocity is large. This causes a strong cross-field diffusion of the hot electrons. In the simulation for this interchange mode, an enhanced temperature relaxation is observed between the hot and cold electrons although the theoretically predicted high frequency modes are stable. (Nogami, K.)

  13. Characteristics of hot electron ring in a simple magnetic mirror field

    International Nuclear Information System (INIS)

    Hosokawa, M.; Ikegami, H.

    1980-12-01

    Characteristics of hot electron ring are studied in a simple magnetic mirror machine (mirror ratio 2 : 1) with a diameter of 30 cm at the midplane and with the distance of 80 cm between the mirrors. Maximum microwave input power is 5 kW at 6.4 GHz with the corresponding power density of approximately 0.3 W/cm 3 . With a background cold plasma of 4 x 10 11 cm -3 , hot electron rings are most effectively generated in two cases when the magnetic field on the axis of the midplane is set near the fundamental or the second harmonic electron cyclotron resonance to the applied microwave frequency. Density profile of the hot electrons is observed to take a so-called ring shape with a radius controllable by the magnetic field intensity and with an axial length of approximately 10 cm. The radial cut view of the ring, however, indicates an M shape density profile, and the density of the hot electrons on the axis is about one half of the density at the ring. Approximately 30 msec is needed before generating the hot electron ring at the density of 10 10 cm -3 with an average kinetic energy of 100 keV. The ultimate energy distribution function is observed to have a stepwise cut in the high energy tail and no energetic components above 1 MeV are detected. The hot electron ring is susceptible to a few instabilities which can be artificially triggered. One of the instabilities is observed to associate with a loss of lower energetic electrons and microwave bursts. At the instability, the ring shape is observed to transform into a filled cylinder in a few microseconds and disappear. (author)

  14. Quantum noise in a terahertz hot electron bolometer mixer

    NARCIS (Netherlands)

    Zhang, W.; Khosropanah, P.; Gao, J. R.; Kollberg, E. L.; Yngvesson, K. S.; Bansal, T.; Barends, R.; Klapwijk, T. M.

    2010-01-01

    We have measured the noise temperature of a single, sensitive superconducting NbN hot electron bolometer (HEB) mixer in a frequency range from 1.6 to 5.3 THz, using a setup with all the key components in vacuum. By analyzing the measured receiver noise temperature using a quantum noise (QN) model

  15. Flute-interchange stability in a hot electron plasma

    International Nuclear Information System (INIS)

    Dominguez, R.R.

    1980-01-01

    Several topics in the kinetic stability theory of flute-interchange modes in a hot electron plasma are discussed. The stability analysis of the hot-electron, curvature-driven flute-interchange mode, previously performed in a slab geometry, is extended to a cylindrical plasma. The cold electron concentration necessary for stability differs substantially from previous criteria. The inclusion of a finite temperature background plasma in the stability analysis results in an ion curvature-driven flute-interchange mode which may be stabilized by either hot-electron diamagnetic effects, hot-electron plasma density, or finite (ion) Larmor radius effects

  16. Perpendicular electron cyclotron emission from hot electrons in TMX-U

    International Nuclear Information System (INIS)

    James, R.A.; Ellis, R.F.; Lasnier, C.J.; Casper, T.A.; Celata, C.M.

    1984-01-01

    Perpendicular electron cyclotron emission (PECE) from the electron cyclotron resonant heating of hot electrons in TMX-U is measured at 30 to 40 and 50 to 75 GHz. This emission is optically thin and is measured at the midplane, f/sub ce/ approx. = 14 GHz, in either end cell. In the west end cell, the emission can be measured at different axial positions thus yielding the temporal history of the hot electron axial profile. These profiles are in excellent agreement with the axial diamagnetic signals. In addition, the PECE signal level correlates well with the diamagnetic signal over a wide range of hot electron densities. Preliminary results from theoretical modeling and comparisons with other diagnostics are also presented

  17. New electron beam facility for irradiated plasma facing materials testing in hot cell

    International Nuclear Information System (INIS)

    Sakamoto, N.; Kawamura, H.; Akiba, M.

    1995-01-01

    Since plasma facing components such as the first wall and the divertor for the next step fusion reactors are exposed to high heat loads and high energy neutron flux generated by the plasma, it is urgent to develop of plasma facing components which can resist these. Then, we have established electron beam heat facility (open-quotes OHBISclose quotes, Oarai Hot-cell electron Beam Irradiating System) at a hot cell in JMTR (Japan Materials Testing Reactor) hot laboratory in order to estimate thermal shock resistivity of plasma facing materials and heat removal capabilities of divertor elements under steady state heating. In this facility, irradiated plasma facing materials (beryllium, carbon based materials and so on) and divertor elements can be treated. This facility consists of an electron beam unit with the maximum beam power of 50kW and the vacuum vessel. The acceleration voltage and the maximum beam current are 30kV (constant) and 1.7A, respectively. The loading time of electron beam is more than 0.1ms. The shape of vacuum vessel is cylindrical, and the mainly dimensions are 500mm in inner diameter, 1000mm in height. The ultimate vacuum of this vessel is 1 x 10 -4 Pa. At present, the facility for thermal shock test has been established in a hot cell. And performance estimation on the electron beam is being conducted. Presently, the devices for heat loading tests under steady state will be added to this facility

  18. New electron beam facility for irradiated plasma facing materials testing in hot cell

    International Nuclear Information System (INIS)

    Shimakawa, S.; Akiba, M.; Kawamura, H.

    1996-01-01

    Since plasma facing components such as the first wall and the divertor for the next step fusion reactors are exposed to high heat loads and high energy neutron flux generated by the plasma, it is urgent to develop plasma facing components which can resist these. We have established electron beam heat facility ('OHBIS', Oarai hot-cell electron beam irradiating system) at a hot cell in JMTR (Japan materials testing reactor) hot laboratory in order to estimate thermal shock resistivity of plasma facing materials and heat removal capabilities of divertor elements under steady state heating. In this facility, irradiated plasma facing materials (beryllium, carbon based materials and so on) and divertor elements can be treated. This facility consists of an electron beam unit with the maximum beam power of 50 kW and the vacuum vessel. The acceleration voltage and the maximum beam current are 30 kV (constant) and 1.7 A, respectively. The loading time of the electron beam is more than 0.1 ms. The shape of vacuum vessel is cylindrical, and the main dimensions are 500 mm in inside diameter, 1000 mm in height. The ultimate vacuum of this vessel is 1 x 10 -4 Pa. At present, the facility for the thermal shock test has been established in a hot cell. The performance of the electron beam is being evaluated at this time. In the future, the equipment for conducting static heat loadings will be incorporated into the facility. (orig.)

  19. Interplay of hot electrons from localized and propagating plasmons.

    Science.gov (United States)

    Hoang, Chung V; Hayashi, Koki; Ito, Yasuo; Gorai, Naoki; Allison, Giles; Shi, Xu; Sun, Quan; Cheng, Zhenzhou; Ueno, Kosei; Goda, Keisuke; Misawa, Hiroaki

    2017-10-03

    Plasmon-induced hot-electron generation has recently received considerable interest and has been studied to develop novel applications in optoelectronics, photovoltaics and green chemistry. Such hot electrons are typically generated from either localized plasmons in metal nanoparticles or propagating plasmons in patterned metal nanostructures. Here we simultaneously generate these heterogeneous plasmon-induced hot electrons and exploit their cooperative interplay in a single metal-semiconductor device to demonstrate, as an example, wavelength-controlled polarity-switchable photoconductivity. Specifically, the dual-plasmon device produces a net photocurrent whose polarity is determined by the balance in population and directionality between the hot electrons from localized and propagating plasmons. The current responsivity and polarity-switching wavelength of the device can be varied over the entire visible spectrum by tailoring the hot-electron interplay in various ways. This phenomenon may provide flexibility to manipulate the electrical output from light-matter interaction and offer opportunities for biosensors, long-distance communications, and photoconversion applications.Plasmon-induced hot electrons have potential applications spanning photodetection and photocatalysis. Here, Hoang et al. study the interplay between hot electrons generated by localized and propagating plasmons, and demonstrate wavelength-controlled polarity-switchable photoconductivity.

  20. Measurements of hot electrons in the Extrap T1 reversed-field pinch

    International Nuclear Information System (INIS)

    Welander, A.; Bergsaaker, H.

    1998-01-01

    The presence of an anisotropic energetic electron population in the edge region is a characteristic feature of reversed-field pinch (RFP) plasmas. In the Extrap T1 RFP, the anisotropic, parallel heat flux in the edge region measured by calorimetry was typically several hundred MWm -2 . To gain more insight into the origin of the hot electron component and to achieve time resolution of the hot electron flow during the discharge, a target probe with a soft x-ray monitor was designed, calibrated and implemented. The x-ray emission from the target was measured with a surface barrier detector covered with a set of different x-ray filters to achieve energy resolution. A calibration in the range 0.5-2 keV electron energy was performed on the same target and detector assembly using a LaB 6 cathode electron gun. The calibration data are interpolated and extrapolated numerically. A directional asymmetry of more than a factor of 100 for the higher energy electrons is observed. The hot electrons are estimated to constitute 10% of the total electron density at the edge and their energy distribution is approximated by a half-Maxwellian with a temperature slightly higher than the central electron temperature. Scalings with plasma current, as well as correlations with local Hα measurements and radial dependences, are presented. (author)

  1. Ion acoustic solitons and supersolitons in a magnetized plasma with nonthermal hot electrons and Boltzmann cool electrons

    Energy Technology Data Exchange (ETDEWEB)

    Rufai, O. R., E-mail: rajirufai@gmail.com; Bharuthram, R., E-mail: rbharuthram@uwc.ac.za [University of the Western Cape, Belville (South Africa); Singh, S. V., E-mail: satyavir@iigs.iigm.res.in; Lakhina, G. S., E-mail: lakhina@iigs.iigm.res.in [Indian Institute of Geomagnetism, New Panvel (W), Navi Mumbai (India)

    2014-08-15

    Arbitrary amplitude, ion acoustic solitons, and supersolitons are studied in a magnetized plasma with two distinct groups of electrons at different temperatures. The plasma consists of a cold ion fluid, cool Boltzmann electrons, and nonthermal energetic hot electrons. Using the Sagdeev pseudo-potential technique, the effect of nonthermal hot electrons on soliton structures with other plasma parameters is studied. Our numerical computation shows that negative potential ion-acoustic solitons and double layers can exist both in the subsonic and supersonic Mach number regimes, unlike the case of an unmagnetized plasma where they can only exist in the supersonic Mach number regime. For the first time, it is reported here that in addition to solitions and double layers, the ion-acoustic supersoliton solutions are also obtained for certain range of parameters in a magnetized three-component plasma model. The results show good agreement with Viking satellite observations of the solitary structures with density depletions in the auroral region of the Earth's magnetosphere.

  2. Measurements of hot electrons in the Extrap T1 reversed-field pinch

    Science.gov (United States)

    Welander, A.; Bergsåker, H.

    1998-02-01

    The presence of an anisotropic energetic electron population in the edge region is a characteristic feature of reversed-field pinch (RFP) plasmas. In the Extrap T1 RFP, the anisotropic, parallel heat flux in the edge region measured by calorimetry was typically several hundred 0741-3335/40/2/011/img1. To gain more insight into the origin of the hot electron component and to achieve time resolution of the hot electron flow during the discharge, a target probe with a soft x-ray monitor was designed, calibrated and implemented. The x-ray emission from the target was measured with a surface barrier detector covered with a set of different x-ray filters to achieve energy resolution. A calibration in the range 0.5-2 keV electron energy was performed on the same target and detector assembly using a 0741-3335/40/2/011/img2 cathode electron gun. The calibration data are interpolated and extrapolated numerically. A directional asymmetry of more than a factor of 100 for the higher energy electrons is observed. The hot electrons are estimated to constitute 10% of the total electron density at the edge and their energy distribution is approximated by a half-Maxwellian with a temperature slightly higher than the central electron temperature. Scalings with plasma current, as well as correlations with local 0741-3335/40/2/011/img3 measurements and radial dependences, are presented.

  3. Electron acoustic-Langmuir solitons in a two-component electron plasma

    Science.gov (United States)

    McKenzie, J. F.

    2003-04-01

    We investigate the conditions under which ‘high-frequency’ electron acoustic Langmuir solitons can be constructed in a plasma consisting of protons and two electron populations: one ‘cold’ and the other ‘hot’. Conservation of total momentum can be cast as a structure equation either for the ‘cold’ or ‘hot’ electron flow speed in a stationary wave using the Bernoulli energy equations for each species. The linearized version of the governing equations gives the dispersion equation for the stationary waves of the system, from which follows the necessary but not sufficient conditions for the existence of soliton structures; namely that the wave speed must be less than the acoustic speed of the ‘hot’ electron component and greater than the low-frequency compound acoustic speed of the two electron populations. In this wave speed regime linear waves are ‘evanescent’, giving rise to the exponential growth or decay, which readily can give rise to non-linear effects that may balance dispersion and allow soliton formation. In general the ‘hot’ component must be more abundant than the ‘cold’ one and the wave is characterized by a compression of the ‘cold’ component and an expansion in the ‘hot’ component necessitating a potential dip. Both components are driven towards their sonic points; the ‘cold’ from above and the ‘hot’ from below. It is this transonic feature which limits the amplitude of the soliton. If the ‘hot’ component is not sufficiently abundant the window for soliton formation shrinks to a narrow speed regime which is quasi-transonic relative to the ‘hot’ electron acoustic speed, and it is shown that smooth solitons cannot be constructed. In the special case of a very cold electron population (i.e. ‘highly supersonic’) and the other population being very hot (i.e. ‘highly subsonic’) with adiabatic index 2, the structure equation simplifies and can be integrated in terms of elementary

  4. Hot-electron nanoscopy using adiabatic compression of surface plasmons

    KAUST Repository

    Giugni, Andrea; Torre, Bruno; Toma, Andrea; Francardi, Marco; Malerba, Mario; Alabastri, Alessandro; Proietti Zaccaria, Remo; Stockman, Mark Mark; Di Fabrizio, Enzo M.

    2013-01-01

    Surface plasmon polaritons are a central concept in nanoplasmonics and have been exploited to develop ultrasensitive chemical detection platforms, as well as imaging and spectroscopic techniques at the nanoscale. Surface plasmons can decay to form highly energetic (or hot) electrons in a process that is usually thought to be parasitic for applications, because it limits the lifetime and propagation length of surface plasmons and therefore has an adverse influence on the functionality of nanoplasmonic devices. Recently, however, it has been shown that hot electrons produced by surface plasmon decay can be harnessed to produce useful work in photodetection, catalysis and solar energy conversion. Nevertheless, the surface-plasmon-to-hot-electron conversion efficiency has been below 1% in all cases. Here we show that adiabatic focusing of surface plasmons on a Schottky diode-terminated tapered tip of nanoscale dimensions allows for a plasmon-to-hot-electron conversion efficiency of ∼30%. We further demonstrate that, with such high efficiency, hot electrons can be used for a new nanoscopy technique based on an atomic force microscopy set-up. We show that this hot-electron nanoscopy preserves the chemical sensitivity of the scanned surface and has a spatial resolution below 50 nm, with margins for improvement.

  5. Hot-electron nanoscopy using adiabatic compression of surface plasmons

    KAUST Repository

    Giugni, Andrea

    2013-10-20

    Surface plasmon polaritons are a central concept in nanoplasmonics and have been exploited to develop ultrasensitive chemical detection platforms, as well as imaging and spectroscopic techniques at the nanoscale. Surface plasmons can decay to form highly energetic (or hot) electrons in a process that is usually thought to be parasitic for applications, because it limits the lifetime and propagation length of surface plasmons and therefore has an adverse influence on the functionality of nanoplasmonic devices. Recently, however, it has been shown that hot electrons produced by surface plasmon decay can be harnessed to produce useful work in photodetection, catalysis and solar energy conversion. Nevertheless, the surface-plasmon-to-hot-electron conversion efficiency has been below 1% in all cases. Here we show that adiabatic focusing of surface plasmons on a Schottky diode-terminated tapered tip of nanoscale dimensions allows for a plasmon-to-hot-electron conversion efficiency of ∼30%. We further demonstrate that, with such high efficiency, hot electrons can be used for a new nanoscopy technique based on an atomic force microscopy set-up. We show that this hot-electron nanoscopy preserves the chemical sensitivity of the scanned surface and has a spatial resolution below 50 nm, with margins for improvement.

  6. Ab initio study of hot electrons in GaAs

    OpenAIRE

    Bernardi, Marco; Vigil-Fowler, Derek; Ong, Chin Shen; Neaton, Jeffrey B.; Louie, Steven G.

    2015-01-01

    Hot carrier dynamics critically impacts the performance of electronic, optoelectronic, photovoltaic, and plasmonic devices. Hot carriers lose energy over nanometer lengths and picosecond timescales and thus are challenging to study experimentally, whereas calculations of hot carrier dynamics are cumbersome and dominated by empirical approaches. In this work, we present ab initio calculations of hot electrons in gallium arsenide (GaAs) using density functional theory and many-body perturbation...

  7. Nonplasmonic Hot-Electron Photocurrents from Mn-Doped Quantum Dots in Photoelectrochemical Cells.

    Science.gov (United States)

    Dong, Yitong; Rossi, Daniel; Parobek, David; Son, Dong Hee

    2016-03-03

    We report the measurement of the hot-electron current in a photoelectrochemical cell constructed from a glass/ITO/Al2 O3 (ITO=indium tin oxide) electrode coated with Mn-doped quantum dots, where hot electrons with a large excess kinetic energy were produced through upconversion of the excitons into hot electron hole pairs under photoexcitation at 3 eV. In our recent study (J. Am. Chem. Soc. 2015, 137, 5549), we demonstrated the generation of hot electrons in Mn-doped II-VI semiconductor quantum dots and their usefulness in photocatalytic H2 production reaction, taking advantage of the more efficient charge transfer of hot electrons compared with band-edge electrons. Here, we show that hot electrons produced in Mn-doped CdS/ZnS quantum dots possess sufficient kinetic energy to overcome the energy barrier from a 5.4-7.5 nm thick Al2 O3 layer producing a hot-electron current in photoelectrochemical cell. This work demonstrates the possibility of harvesting hot electrons not only at the interface of the doped quantum dot surface, but also far away from it, thus taking advantage of the capability of hot electrons for long-range electron transfer across a thick energy barrier. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Dual-mode operation of 2D material-base hot electron transistors

    KAUST Repository

    Lan, Yann-Wen; Jr., Carlos M. Torres,; Zhu, Xiaodan; Qasem, Hussam; Adleman, James R.; Lerner, Mitchell B.; Tsai, Shin-Hung; Shi, Yumeng; Li, Lain-Jong; Yeh, Wen-Kuan; Wang, Kang L.

    2016-01-01

    Vertical hot electron transistors incorporating atomically-thin 2D materials, such as graphene or MoS2, in the base region have been proposed and demonstrated in the development of electronic and optoelectronic applications. To the best of our knowledge, all previous 2D material-base hot electron transistors only considered applying a positive collector-base potential (V-CB > 0) as is necessary for the typical unipolar hot-electron transistor behavior. Here we demonstrate a novel functionality, specifically a dual-mode operation, in our 2D material-base hot electron transistors (e.g. with either graphene or MoS2 in the base region) with the application of a negative collector-base potential (V-CB < 0). That is, our 2D material-base hot electron transistors can operate in either a hot-electron or a reverse-current dominating mode depending upon the particular polarity of VCB. Furthermore, these devices operate at room temperature and their current gains can be dynamically tuned by varying VCB. We anticipate our multi-functional dual-mode transistors will pave the way towards the realization of novel flexible 2D material-based high-density and low-energy hot-carrier electronic applications.

  9. Dual-mode operation of 2D material-base hot electron transistors

    KAUST Repository

    Lan, Yann-Wen

    2016-09-01

    Vertical hot electron transistors incorporating atomically-thin 2D materials, such as graphene or MoS2, in the base region have been proposed and demonstrated in the development of electronic and optoelectronic applications. To the best of our knowledge, all previous 2D material-base hot electron transistors only considered applying a positive collector-base potential (V-CB > 0) as is necessary for the typical unipolar hot-electron transistor behavior. Here we demonstrate a novel functionality, specifically a dual-mode operation, in our 2D material-base hot electron transistors (e.g. with either graphene or MoS2 in the base region) with the application of a negative collector-base potential (V-CB < 0). That is, our 2D material-base hot electron transistors can operate in either a hot-electron or a reverse-current dominating mode depending upon the particular polarity of VCB. Furthermore, these devices operate at room temperature and their current gains can be dynamically tuned by varying VCB. We anticipate our multi-functional dual-mode transistors will pave the way towards the realization of novel flexible 2D material-based high-density and low-energy hot-carrier electronic applications.

  10. Electronic components

    CERN Document Server

    Colwell, Morris A

    1976-01-01

    Electronic Components provides a basic grounding in the practical aspects of using and selecting electronics components. The book describes the basic requirements needed to start practical work on electronic equipment, resistors and potentiometers, capacitance, and inductors and transformers. The text discusses semiconductor devices such as diodes, thyristors and triacs, transistors and heat sinks, logic and linear integrated circuits (I.C.s) and electromechanical devices. Common abbreviations applied to components are provided. Constructors and electronics engineers will find the book useful

  11. X-ray spectroscopy of warm and hot electron components in the CAPRICE source plasma at EIS testbench at GSI.

    Science.gov (United States)

    Mascali, D; Celona, L; Maimone, F; Maeder, J; Castro, G; Romano, F P; Musumarra, A; Altana, C; Caliri, C; Torrisi, G; Neri, L; Gammino, S; Tinschert, K; Spaedtke, K P; Rossbach, J; Lang, R; Ciavola, G

    2014-02-01

    An experimental campaign aiming to detect X radiation emitted by the plasma of the CAPRICE source - operating at GSI, Darmstadt - has been carried out. Two different detectors (a SDD - Silicon Drift Detector and a HpGe - hyper-pure Germanium detector) have been used to characterize the warm (2-30 keV) and hot (30-500 keV) electrons in the plasma, collecting the emission intensity and the energy spectra for different pumping wave frequencies and then correlating them with the CSD of the extracted beam measured by means of a bending magnet. A plasma emissivity model has been used to extract the plasma density along the cone of sight of the SDD and HpGe detectors, which have been placed beyond specific collimators developed on purpose. Results show that the tuning of the pumping frequency considerably modifies the plasma density especially in the warm electron population domain, which is the component responsible for ionization processes: a strong variation of the plasma density near axis region has been detected. Potential correlations with the charge state distribution in the plasma are explored.

  12. Hot-electron-based solar energy conversion with metal-semiconductor nanodiodes

    Science.gov (United States)

    Lee, Young Keun; Lee, Hyosun; Lee, Changhwan; Hwang, Euyheon; Park, Jeong Young

    2016-06-01

    Energy dissipation at metal surfaces or interfaces between a metal and a dielectric generally results from elementary excitations, including phonons and electronic excitation, once external energy is deposited to the surface/interface during exothermic chemical processes or an electromagnetic wave incident. In this paper, we outline recent research activities to develop energy conversion devices based on hot electrons. We found that photon energy can be directly converted to hot electrons and that hot electrons flow through the interface of metal-semiconductor nanodiodes where a Schottky barrier is formed and the energy barrier is much lower than the work function of the metal. The detection of hot electron flow can be successfully measured using the photocurrent; we measured the photoyield of photoemission with incident photons-to-current conversion efficiency (IPCE). We also show that surface plasmons (i.e. the collective oscillation of conduction band electrons induced by interaction with an electromagnetic field) are excited on a rough metal surface and subsequently decay into secondary electrons, which gives rise to enhancement of the IPCE. Furthermore, the unique optical behavior of surface plasmons can be coupled with dye molecules, suggesting the possibility for producing additional channels for hot electron generation.

  13. Quantum noise in a terahertz hot electron bolometer mixer

    OpenAIRE

    Zhang, W.; Khosropanah, P.; Gao, J. R.; Kollberg, E. L.; Yngvesson, K. S.; Bansal, T.; Barends, R.; Klapwijk, T. M.

    2010-01-01

    We have measured the noise temperature of a single, sensitive superconducting NbN hot electron bolometer (HEB) mixer in a frequency range from 1.6 to 5.3 THz, using a setup with all the key components in vacuum. By analyzing the measured receiver noise temperature using a quantum noise (QN) model for HEB mixers, we confirm the effect of QN. The QN is found to be responsible for about half of the receiver noise at the highest frequency in our measurements. The ?-factor (the quantum efficiency ...

  14. The effect of hot electrons and surface plasmons on heterogeneous catalysis

    International Nuclear Information System (INIS)

    Kim, Sun Mi; Lee, Si Woo; Moon, Song Yi; Park, Jeong Young

    2016-01-01

    Hot electrons and surface-plasmon-driven chemistry are amongst the most actively studied research subjects because they are deeply associated with energy dissipation and the conversion processes at the surface and interfaces, which are still open questions and key issues in the surface science community. In this topical review, we give an overview of the concept of hot electrons or surface-plasmon-mediated hot electrons generated under various structural schemes (i.e. metals, metal–semiconductor, and metal–insulator–metal) and their role affecting catalytic activity in chemical reactions. We highlight recent studies on the relation between hot electrons and catalytic activity on metallic surfaces. We discuss possible mechanisms for how hot electrons participate in chemical reactions. We also introduce controlled chemistry to describe specific pathways for selectivity control in catalysis on metal nanoparticles. (topical review)

  15. Dual-mode operation of 2D material-base hot electron transistors.

    Science.gov (United States)

    Lan, Yann-Wen; Torres, Carlos M; Zhu, Xiaodan; Qasem, Hussam; Adleman, James R; Lerner, Mitchell B; Tsai, Shin-Hung; Shi, Yumeng; Li, Lain-Jong; Yeh, Wen-Kuan; Wang, Kang L

    2016-09-01

    Vertical hot electron transistors incorporating atomically-thin 2D materials, such as graphene or MoS2, in the base region have been proposed and demonstrated in the development of electronic and optoelectronic applications. To the best of our knowledge, all previous 2D material-base hot electron transistors only considered applying a positive collector-base potential (VCB > 0) as is necessary for the typical unipolar hot-electron transistor behavior. Here we demonstrate a novel functionality, specifically a dual-mode operation, in our 2D material-base hot electron transistors (e.g. with either graphene or MoS2 in the base region) with the application of a negative collector-base potential (VCB transistors can operate in either a hot-electron or a reverse-current dominating mode depending upon the particular polarity of VCB. Furthermore, these devices operate at room temperature and their current gains can be dynamically tuned by varying VCB. We anticipate our multi-functional dual-mode transistors will pave the way towards the realization of novel flexible 2D material-based high-density and low-energy hot-carrier electronic applications.

  16. Sheath formation of a plasma containing multiply charged ions, cold and hot electrons, and emitted electrons

    International Nuclear Information System (INIS)

    You, H.J.

    2012-01-01

    It is quite well known that ion confinement is an important factor in an electron cyclotron resonance ion source (ECRIS) as it is closely related to the plasma potential. A model of sheath formation was extended to a plasma containing multiply charged ions (MCIs), cold and hot electrons, and secondary electrons emitted either by MCIs or hot electrons. In the model, a modification of the 'Bohm criterion' was given, the sheath potential drop and the critical emission condition were also analyzed. It appears that the presence of hot electrons and emitted electrons strongly affects the sheath formation so that smaller hot electrons and larger emission current result in reduced sheath potential (or floating potential). However the sheath potential was found to become independent of the emission current J when J > J c , (where J c is the critical emission current. The paper is followed by the associated poster

  17. Radial structure of curvature-driven instabilities in a hot-electron plasma

    International Nuclear Information System (INIS)

    Spong, D.A.; Berk, H.L.; Van Dam, J.W.

    1984-01-01

    A nonlocal analysis of curvature-driven instabilities for a hot-electron ring interacting with a warm background plasma has been made. Four different instability modes characteristic of hot-electron plasmas have been examined: the high-frequency hot-electron interchange (at frequencies larger than the ion-cyclotron frequency), the compressional Alfven instability, the interacting background pressure-driven interchange, and the conventional hot-electron interchange (at frequencies below the ion-cyclotron frequency). The decoupling condition between core and hot-electron plasmas has also been examined, and its influence on the background and hot-electron interchange stability boundaries has been studied. The assumed equilibrium plasma profiles and resulting radial mode structure differ somewhat from those used in previous local analytic estimates; however, when the analysis is calibrated to the appropriate effective radial wavelength of the nonlocal calculation, reasonable agreement is obtained. Comparison with recent experimental measurements indicates that certain of these modes may play a role in establishing operating boundaries for the ELMO Bumpy Torus-Scale (EBT-S) experiment. The calculations given here indicate the necessity of having core plasma outside the ring to prevent the destabilizing wave resonance of the precessional mode with a cold plasma

  18. THE USE OF COATINGS FOR HOT CORROSION AND EROSION PROTECTION IN TURBINE HOT SECTION COMPONENTS

    Directory of Open Access Journals (Sweden)

    Hayrettin AHLATCI

    1999-01-01

    Full Text Available High pressure turbine components are subjected to a wide variety of thermal and mechanical loading during service. In addition, the components are exposed to a highly oxidizing atmosphere which may contain contaminants such as sulphates, chlorides and sulphuorous gases along with erosive media. So the variety of surface coatings and deposition processes available for the protection of blade and vane components in gas turbines are summarised in this study. Coating types range from simple diffusion aluminides to modified aluminides and a CoCrAlY overlayer. The recommendations for corrosion-resistant coatings (for low temperature and high temperature hot corrosion environments are as follows: silicon aluminide and platinumchromium aluminide for different gas turbine section superalloys substrates. Platinum metal additions are used to improve the properties of coatings on turbine components. Inorganic coatings based on ceramic films which contain aluminium or aluminium and silicon are very effective in engines and gas turbines. Diffusion, overlayer and thermal barrier coatings which are deposited on superalloys gas turbine components by pack cementation, plasma spraying processes and a number of chemical vapour deposition, physical vapour deposition processes (such as electron beam, sputtering, ion plating are described. The principles underlying the development of protective coatings serve as a useful guide in the choice of coatings for other high temperature applications.

  19. X-ray spectroscopy of warm and hot electron components in the CAPRICE source plasma at EIS testbench at GSI

    Energy Technology Data Exchange (ETDEWEB)

    Mascali, D., E-mail: davidmascali@lns.infn.it; Celona, L.; Castro, G.; Torrisi, G.; Neri, L.; Gammino, S.; Ciavola, G. [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, – Via S. Sofia 62, 95123 Catania (Italy); Maimone, F.; Maeder, J.; Tinschert, K.; Spaedtke, K. P.; Rossbach, J.; Lang, R. [GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstrasse 1, 64291 Darmstadt (Germany); Romano, F. P. [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, – Via S. Sofia 62, 95123 Catania (Italy); IBAM, CNR, Via Biblioteca 4, 95124 Catania (Italy); Musumarra, A.; Altana, C.; Caliri, C. [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali del Sud, – Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Università degli Studi di Catania, via S. Sofia 64, 95123 Catania (Italy)

    2014-02-15

    An experimental campaign aiming to detect X radiation emitted by the plasma of the CAPRICE source – operating at GSI, Darmstadt – has been carried out. Two different detectors (a SDD – Silicon Drift Detector and a HpGe – hyper-pure Germanium detector) have been used to characterize the warm (2–30 keV) and hot (30–500 keV) electrons in the plasma, collecting the emission intensity and the energy spectra for different pumping wave frequencies and then correlating them with the CSD of the extracted beam measured by means of a bending magnet. A plasma emissivity model has been used to extract the plasma density along the cone of sight of the SDD and HpGe detectors, which have been placed beyond specific collimators developed on purpose. Results show that the tuning of the pumping frequency considerably modifies the plasma density especially in the warm electron population domain, which is the component responsible for ionization processes: a strong variation of the plasma density near axis region has been detected. Potential correlations with the charge state distribution in the plasma are explored.

  20. Jumping-droplet electronics hot-spot cooling

    Science.gov (United States)

    Oh, Junho; Birbarah, Patrick; Foulkes, Thomas; Yin, Sabrina L.; Rentauskas, Michelle; Neely, Jason; Pilawa-Podgurski, Robert C. N.; Miljkovic, Nenad

    2017-03-01

    Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm × 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobic surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22-25 °C air temperature, 20%-45% relative humidity) to determine the effect of gap spacing (2-4 mm), electric field (50-250 V/cm) and applied heat flux (demonstrated to 13 W/cm2). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm2. This work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.

  1. Jumping-droplet electronics hot-spot cooling

    International Nuclear Information System (INIS)

    Oh, Junho; Birbarah, Patrick; Foulkes, Thomas; Yin, Sabrina L.; Rentauskas, Michelle

    2017-01-01

    Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm x 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobic surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22-25°C air temperature, 20-45% relative humidity) to determine the effect of gap spacing (2-4 mm), electric field (50-250 V/cm), and heat flux (demonstrated to 13 W/cm"2). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈ 200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm"2. Finally, this work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.

  2. Measurements of hot spots and electron beams in Z-pinch devices

    International Nuclear Information System (INIS)

    Deeney, C.

    1988-04-01

    Hot spots and Electron Beams have been observed in different types of Z-pinches. There is, however, no conclusive evidence on how either are formed although there has been much theoretical interest in both these phenomena. In this thesis, nanosecond time resolved and time correlated, X-ray and optical diagnostics, are performed on two different types of Z-pinch: a 4 kJ, 30 kV Gas Puff Z-pinch and a 28 kJ, 60 kV Plasma Focus. The aim being to study hot spots and electron beams, as well as characterise the plasma, two different Z-pinch devices. Computer codes are developed to analyse the energy and time resolved data obtained in this work. These codes model both, X-ray emission from a plasma and X-ray emission due to electron beam bombardment of a metal surface. The hot spot and electron beam parameters are measured, from the time correlated X-ray data using these computer codes. The electron beams and the hot spots are also correlated to the plasma behaviour and to each other. The results from both devices are compared with each other and with the theoretical work on hot spot and electron beam formation. A previously unreported 3-5 keV electron temperature plasma is identified, in the gas puff Z-pinch plasma, prior to the formation of the hot spots. it is shown, therefore, that the hot spots are more dense but not hotter than the surrounding plasma. Two distinct periods of electron beam generation are identified in both devices. (author)

  3. Curvature-driven instabilities in a hot-electron plasma: radial analysis

    International Nuclear Information System (INIS)

    Berk, H.L.; Van Dam, J.W.; Rosenbluth, M.N.; Spong, D.A.

    1981-12-01

    The theory of unfavorable curvature-driven instabilities is developed for a plasma interacting with a hot electron ring whose drift frequencies are larger than the growth rates predicted from conventional magnetohydrodynamic theory. A z-pinch model is used to emphasize the radial structure of the problem. Stability criteria are obtained for the five possible modes of instability: the conventional hot electron interchange, a high-frequency hot electron interchange (at frequencies larger than the ion cyclotron frequency), a compressional instability, a background pressure-driven interchange, and an interacting pressure-driven interchange

  4. Heat transfer between adsorbate and laser-heated hot electrons

    International Nuclear Information System (INIS)

    Ueba, H; Persson, B N J

    2008-01-01

    Strong short laser pulses can give rise to a strong increase in the electronic temperature at metal surfaces. Energy transfer from the hot electrons to adsorbed molecules may result in adsorbate reactions, e.g. desorption or diffusion. We point out the limitations of an often used equation to describe the heat transfer process in terms of a friction coupling. We propose a simple theory for the energy transfer between the adsorbate and hot electrons using a newly introduced heat transfer coefficient, which depends on the adsorbate temperature. We calculate the transient adsorbate temperature and the reaction yield for a Morse potential as a function of the laser fluency. The results are compared to those obtained using a conventional heat transfer equation with temperature-independent friction. It is found that our equation of energy (heat) transfer gives a significantly lower adsorbate peak temperature, which results in a large modification of the reaction yield. We also consider the heat transfer between different vibrational modes excited by hot electrons. This mode coupling provides indirect heating of the vibrational temperature in addition to the direct heating by hot electrons. The formula of heat transfer through linear mode-mode coupling of two harmonic oscillators is applied to the recent time-resolved study of carbon monoxide and atomic oxygen hopping on an ultrafast laser-heated Pt(111) surface. It is found that the maximum temperature of the frustrated translation mode can reach high temperatures for hopping, even when direct friction coupling to the hot electrons is not strong enough

  5. Hot gas path component cooling system

    Science.gov (United States)

    Lacy, Benjamin Paul; Bunker, Ronald Scott; Itzel, Gary Michael

    2014-02-18

    A cooling system for a hot gas path component is disclosed. The cooling system may include a component layer and a cover layer. The component layer may include a first inner surface and a second outer surface. The second outer surface may define a plurality of channels. The component layer may further define a plurality of passages extending generally between the first inner surface and the second outer surface. Each of the plurality of channels may be fluidly connected to at least one of the plurality of passages. The cover layer may be situated adjacent the second outer surface of the component layer. The plurality of passages may be configured to flow a cooling medium to the plurality of channels and provide impingement cooling to the cover layer. The plurality of channels may be configured to flow cooling medium therethrough, cooling the cover layer.

  6. Nonequilibrium statistical operator in hot-electron transport theory

    International Nuclear Information System (INIS)

    Xing, D.Y.; Liu, M.

    1991-09-01

    The Nonequilibrium Statistical Operator method developed by Zubarev is generalized and applied to the study of hot-electron transport in semiconductors. The steady-state balance equations for momentum and energy are derived to the lowest order in the electron-lattice coupling. We show that the derived balance equations are exactly the same as those obtained by Lei and Ting. This equivalence stems from the fact that to the linear order in the electron-lattice coupling, two statistical density matrices have identical effect when they are used to calculate the average value of a dynamical operator. The application to the steady-state and transient hot-electron transport in multivalley semiconductors is also discussed. (author). 28 refs, 1 fig

  7. Conceptual design and simulation investigation of an electronic cooling device powered by hot electrons

    International Nuclear Information System (INIS)

    Su, Guozhen; Zhang, Yanchao; Cai, Ling; Su, Shanhe; Chen, Jincan

    2015-01-01

    Most electronic cooling devices are powered by an external bias applied between the cold and the hot reservoirs. Here we propose a new concept of electronic cooling, in which cooling is achieved by using a reservoir of hot electrons as the power source. The cooling device incorporates two energy filters with the Lorentzian transmission function to respectively select low- and high-energy electrons for transport. Based on the proposed model, we analyze the performances of the device varying with the resonant levels and half widths of two energy filters and establish the optimal configuration of the cooling device. It is believed that such a novel device may be practically used in some nano-energy fields. - Highlights: • A new electronic cooling device powered by hot electrons is proposed. • Two energy filters are employed to select the electrons for transport. • The effects of the resonant levels and half widths of two filters are discussed. • The maximum cooling power and coefficient of performance are calculated. • The optimal configuration of the cooling device is determined.

  8. Superconducting hot-electron bolometer: from the discovery of hot-electron phenomena to practical applications

    International Nuclear Information System (INIS)

    Shurakov, A; Lobanov, Y; Goltsman, G

    2016-01-01

    The discovery of hot-electron phenomena in a thin superconducting film in the last century was followed by numerous experimental studies of its appearance in different materials aiming for a better understanding of the phenomena and consequent implementation of terahertz detection systems for practical applications. In contrast to the competitors such as superconductor-insulator-superconductor tunnel junctions and Schottky diodes, the hot electron bolometer (HEB) did not demonstrate any frequency limitation of the detection mechanism. The latter, in conjunction with a decent performance, rapidly made the HEB mixer the most attractive candidate for heterodyne observations at frequencies above 1 THz. The successful operation of practical instruments (the Heinrich Hertz Telescope, the Receiver Lab Telescope, APEX, SOFIA, Hershel) ensures the importance of the HEB technology despite the lack of rigorous theoretical routine for predicting the performance. In this review, we provide a summary of experimental and theoretical studies devoted to understanding the HEB physics, and an overview of various fabrication routes and materials. (topical review)

  9. Linear electrostatic waves in a three-component electron-positron-ion plasma

    Energy Technology Data Exchange (ETDEWEB)

    Mugemana, A., E-mail: mugemanaa@gmail.com; Moolla, S. [School of Chemistry and Physics, University of KwaZulu-Natal, Durban 4000 (South Africa); Lazarus, I. J. [Department of Mathematics, Statistics and Physics, Durban University of Technology, Durban 4000 (South Africa)

    2014-12-15

    Analytical linear electrostatic waves in a magnetized three-component electron-positron-ion plasma are studied in the low-frequency limit. By using the continuity and momentum equations with Poisson's equation, the dispersion relation for the electron-positron-ion plasma consisting of cool ions, and hot Boltzmann electrons and positrons is derived. In the linear regime, the propagation of two possible modes and their evolution are studied. In the cases of parallel and perpendicular propagation, it is shown that these two possible modes are always stable. The present investigation contributes to nonlinear propagation of electrostatic waves in space and the laboratory.

  10. Hot-electron surface retention in intense short-pulse laser-matter interactions.

    Science.gov (United States)

    Mason, R J; Dodd, E S; Albright, B J

    2005-07-01

    Implicit hybrid plasma simulations predict that a significant fraction of the energy deposited into hot electrons can be retained near the surface of targets with steep density gradients illuminated by intense short-pulse lasers. This retention derives from the lateral transport of heated electrons randomly emitted in the presence of spontaneous magnetic fields arising near the laser spot, from geometric effects associated with a small hot-electron source, and from E fields arising in reaction to the ponderomotive force. Below the laser spot hot electrons are axially focused into a target by the B fields, and can filament in moderate Z targets by resistive Weibel-like instability, if the effective background electron temperature remains sufficiently low. Carefully engineered use of such retention in conjunction with ponderomotive density profile steepening could result in a reduced hot-electron range that aids fast ignition. Alternatively, such retention may disturb a deeper deposition needed for efficient radiography and backside fast ion generation.

  11. Hot electron formation in thermal barrier region of tandem mirror GAMMA 10

    International Nuclear Information System (INIS)

    Katanuma, I.; Kiwamoto, Y.; Sawada, K.; Miyoshi, S.

    1987-01-01

    We have studied the hot electron build-up by the second harmonic electron cyclotron resonance heating in the thermal barrier region of tandem mirror GAMMA 10 by using a Fokker-Planck code with self-consistent potential profile taken into account. We have found two phases in the evolution of hot electron population and the potential profile. In the first phase where the RF diffusion is dominant quick increase of the hot electron density and that of the mean energy are observed. No further increase in the mean energy is observed thereafter. The potential is the deepest during the first phase. The second phase starts in the mean-free-time of the pitch angle scattering of hot electrons on cold electrons and ions. In this phase the hot electron population increases in the rate of the pitch angle scattering. The potential dip shallows due to the accumulation of pitch angle scattered passing ions. This observation indicates the necessity of the ion pumping for maintaining the negative potential at the thermal barrier. (author)

  12. Effects of magnetic configuration on hot electrons in highly charged ECR plasma

    International Nuclear Information System (INIS)

    Zhao, H Y; Zhao, H W; Sun, L T; Wang, H; Ma, B H; Zhang, X Zh; Li, X X; Ma, X W; Zhu, Y H; Lu, W; Shang, Y; Xie, D Z

    2009-01-01

    To investigate the hot electrons in highly charged electron cyclotron resonance (ECR) plasma, Bremsstrahlung radiations were measured on two ECR ion sources at the Institute of Modern Physics. Used as a comparative index of the mean energy of the hot electrons, a spectral temperature, T spe , is derived through a linear fitting of the spectra in a semi-logarithmic representation. The influences of the external source parameters, especially the magnetic configuration, on the hot electrons are studied systematically. This study has experimentally demonstrated the importance of high microwave frequency and high magnetic field in the electron resonance heating to produce a high density of hot electrons, which is consistent with the empirical ECR scaling laws. The experimental results have again shown that a good compromise is needed between the ion extraction and the plasma confinement for an efficient production of highly charged ion beams. In addition, this investigation has shown that the correlation between the mean energy of the hot electrons and the magnetic field gradient at the ECR is well in agreement with the theoretical models.

  13. Experiments on hot-electron ECRH in the Tandem Mirror Experiment-Upgrade

    International Nuclear Information System (INIS)

    Stallard, B.W.

    1983-01-01

    Experiments have begun on the Tandem Mirror Experiment Upgrade (TMX-U) using electron-cyclotron resonant heating (ECRH) to generate the hot electron populations required for thermal barrier operation (Energy E/sub eh/ approx. 50 keV, density n/sub eh/ 12 , and hot-to-cold fraction n/sub eh/n approx. 0.9). For this operation, rf power produced by 28-GHz gyrotrons is injected with extraordinary mode polarization at both fundamental and second harmonic locations. Our initial experiments, which concentrated on startup of the hot electrons, were carried out at low density ( 12 cm - 3 ) where Fokker-Planck calculations predict high heating efficiency when the electron temperature (T/sub e/) is low. Under these conditions, we produced substantial hot electron populations (diamagnetic energy > 400 J, E/sub eh/ in the range of 15 to 50 keV, and n/sub eh//n > 0.5)

  14. The optimization of production and control of hot-electron plasmas

    International Nuclear Information System (INIS)

    1989-01-01

    The present project was initially undertaken to develop a number of innovative concepts for using electron cyclotron heating (ECH) to enhance tokamak performance. A common feature of the various applications under consideration is efficient, spatially-localized generation of hot-electron plasmas; and the first phase of the work addressed the basic aspects of an approach to achieving this Upper Off-Resonant Heating (UORH) and open-resonator couplers to confine the weakly damped microwave power to the particular region where the hot electrons are to be generated. The results of the first year's work provided strong evidence that hot-electron plasmas with electron energies of hundreds of keV could be generated using multiple-frequency ECH and fully-toroidal open-resonator couplers. The evidence was sufficiently compelling to suggest that the project be focused on a suitable near-term application to the TEXT device

  15. Effect of hot air drying on volatile compounds of Flammulina velutipes detected by HS-SPME-GC-MS and electronic nose.

    Science.gov (United States)

    Yang, Wenjian; Yu, Jie; Pei, Fei; Mariga, Alfred Mugambi; Ma, Ning; Fang, Yong; Hu, Qiuhui

    2016-04-01

    Volatile compounds are important factors that affect the flavor quality of Flammulina velutipes, but the changes occurring during hot air drying is still unclear. To clarify the dynamic changes of flavor components during hot air drying, comprehensive flavor characterization and volatile compounds of F. velutipes were evaluated using electronic nose technology and headspace solid phase micro-extraction combined with gas chromatography-mass spectrometry (HS-SPME-GC-MS), respectively. Results showed that volatile components in F. velutipes significantly changed during hot air drying according to the principal component analysis and radar fingerprint chart of electronic nose. Volatile compounds of fresh F. velutipes consisted mainly of ketones, aldehydes and alcohols, and 3-octanone was the dominant compound. Drying process could significantly decrease the relative content of ketones and promoted the generation of alcohols, acids, and esters, which became the main volatile compounds of dried F. velutipes. These may provide a theoretical basis for the formation mechanism of flavor substances in dried F. velutipes. Copyright © 2015 Elsevier Ltd. All rights reserved.

  16. Hot laboratory design on the basis of standardized components

    International Nuclear Information System (INIS)

    Cadrot, J.

    1976-01-01

    The paper describes the principal effects on hot laboratory design brought about over the last 15 years by the use of standardized components developed jointly with the CEA and the industrial associates of AFINE. After a rapid survey of the various advantages of standardization, the author turns to the specific case of a laboratory producing mixed plutonium and uranium oxide fuels, giving a brief description of the glove-boxes and ancillary equipment. He then deals with the design of an isotope production laboratory. The basic component is the DR 200 standard cell, which permits the civil engineering work to be effected on modular principles. Use of a safety-flow pressure regulating valve makes possible pneumatic automation of the production-cell internals. A substantial gain in output is the result. In the next section the paper refers to a pilot facility for irradiated fuel studies, and describes the components used, which require taking into account the high activities and intense radiations encountered in studies of this type. The author then demonstrates the flexibility with which standardized components can be adapted to different uses, thus solving many distinct problems, an example of which is represented by a semi-hot box for handling up to 100g of americium-241. Finally, the paper offers a rapid summary of the effects of standardization at the various stages concerned, from initial design to the commissioning of a hot laboratory. (author)

  17. Hot-electron effect in spin relaxation of electrically injected electrons in intrinsic Germanium.

    Science.gov (United States)

    Yu, T; Wu, M W

    2015-07-01

    The hot-electron effect in the spin relaxation of electrically injected electrons in intrinsic germanium is investigated by the kinetic spin Bloch equations both analytically and numerically. It is shown that in the weak-electric-field regime with E ≲ 0.5 kV cm(-1), our calculations have reasonable agreement with the recent transport experiment in the hot-electron spin-injection configuration (2013 Phys. Rev. Lett. 111 257204). We reveal that the spin relaxation is significantly enhanced at low temperature in the presence of weak electric field E ≲ 50 V cm(-1), which originates from the obvious center-of-mass drift effect due to the weak electron-phonon interaction, whereas the hot-electron effect is demonstrated to be less important. This can explain the discrepancy between the experimental observation and the previous theoretical calculation (2012 Phys. Rev. B 86 085202), which deviates from the experimental results by about two orders of magnitude at low temperature. It is further shown that in the strong-electric-field regime with 0.5 ≲ E ≲ 2 kV cm(-1), the spin relaxation is enhanced due to the hot-electron effect, whereas the drift effect is demonstrated to be marginal. Finally, we find that when 1.4 ≲ E ≲ 2 kV cm(-1) which lies in the strong-electric-field regime, a small fraction of electrons (≲5%) can be driven from the L to Γ valley, and the spin relaxation rates are the same for the Γ and L valleys in the intrinsic sample without impurity. With the negligible influence of the spin dynamics in the Γ valley to the whole system, the spin dynamics in the L valley can be measured from the Γ valley by the standard direct optical transition method.

  18. Spin dependent transport of hot electrons through ultrathin epitaxial metallic films

    Energy Technology Data Exchange (ETDEWEB)

    Heindl, Emanuel

    2010-06-23

    In this work relaxation and transport of hot electrons in thin single crystalline metallic films is investigated by Ballistic Electron Emission Microscopy. The electron mean free paths are determined in an energy interval of 1 to 2 eV above the Fermi level. While fcc Au-films appear to be quite transmissive for hot electrons, the scattering lengths are much shorter for the ferromagnetic alloy FeCo revealing, furthermore, a strong spin asymmetry in hot electron transport. Additional information is gained from temperature dependent studies in combination with golden rule approaches in order to disentangle the impact of several relaxation and transport properties. It is found that bcc Fe-films are much less effective in spin filtering than films made of the FeCo-alloy. (orig.)

  19. VIRTUAL ELECTRONIC COMPONENTS OF THE ELECTRONIC EQUIPMENT

    Directory of Open Access Journals (Sweden)

    E. Lazarevich

    2013-01-01

    Full Text Available The article is present new idea of the creation, developments and improvements of the electronic equipment of complex systems by means of the virtual electronic components. The idea of the virtual electronic components is a presentation and perception of the creation and developments of the equipment on two forming: real – in the manner of standard marketed block of the intellectual property and image – in the manner of virtual component. The real component in most cases slows the development of the electronic equipment. The imaginary component is the «locomotive» of development of the electronic equipment. The Imaginary component contains the scientific has brushed against developer. The scientific has brushed against developer reveals of itself in the manner of virtual component on the modern level of the design rates of microelectronics.

  20. Stimulated Raman scattering and hot-electron production

    International Nuclear Information System (INIS)

    Drake, R.P.; Turner, R.E.; Lasinski, B.F.; Estabrook, K.G.; Campbell, E.M.; Wang, C.L.; Phillion, D.W.; Williams, E.A.; Kruer, W.L.

    1985-01-01

    High-intensity laser light can excite parametric instabilities that scatter or absorb it. One instability that can arise when laser light penetrates a plasma is sub-quarter-critical stimulated Raman (SQSR) scattering. It occurs below the quarter-critical density of the incident light and involves the decay of the incident light wave into a scattered light wave and electron plasma wave. The scattered-light wavelength ranges from 1 to 2 times that of the incident light, depending on the plasma density and temperature. This article reports studies of SQSR scattering and hot-electron production in plasmas produced by irradiating thick gold targets with up to 4 kJ of 0.53-μm light in 1-ns (FWHM) pulses. These studies have important implications for laser fusion. Hot electrons attributed to the SQSR instability can increase the difficulty of achieving high-gain implosions by penetrating and preheating the fusion fuel

  1. Ponderomotive Acceleration of Hot Electrons in Tenuous Plasmas

    International Nuclear Information System (INIS)

    Geyko, V.I.; Fraiman, G.M.; Dodin, I.Y.; Fisch, N.J.

    2009-01-01

    The oscillation-center Hamiltonian is derived for a relativistic electron injected with an arbitrary momentum in a linearly polarized laser pulse propagating in tenuous plasma, assuming that the pulse length is smaller than the plasma wavelength. For hot electrons generated at collisions with ions under intense laser drive, multiple regimes of ponderomotive acceleration are identified and the laser dispersion is shown to affect the process at plasma densities down to 10 17 cm -3 . Assuming a/γ g 0 ∼ g , where a is the normalized laser field, and γ g is the group velocity Lorentz factor. Yet γ ∼ Γ is attained within a wide range of initial conditions; hence a cutoff in the hot electron distribution is predicted

  2. Anisotropy effects on curvature-driven flute instabilities in a hot-electron plasma

    International Nuclear Information System (INIS)

    Spong, D.A.; Berk, H.L.; Van Dam, J.W.; Rosenbluth, M.N.

    1982-08-01

    The effects of finite parallel temperature are investigated for a hot electron plasma with sufficiently large beta that the magnetic field scale length (Δ/sub B/) is small compared with the vacuum field radius of curvature (R). Numerical and analytical estimates of stability boundaries are obtained for the four possible modes that can be treated in this limit: the conventional hot electron interchange, the high frequency hot electron interchange (ω > ω/sub ci/), the compressional Alfven mode, and the interacting pressure-driven interchange

  3. Hot-electron plasma formation and confinement in the Tandem Mirror Experiment-Upgrade

    International Nuclear Information System (INIS)

    Ress, D.B.

    1988-01-01

    Electron-cyclotron range-of-frequency heating (ECRH) at 28 GHz is used to create a population of mirror-confined hot electrons in the Tandem Mirror Experiment-Upgrade (TMX-U). Generation of a large fraction of such electrons within each end-cell of TMX-U is essential to the formation of the desired electrostatic potential profile of the thermal-barrier tandem mirror. The formation and confinement of the ECRH-generated hot-electron plasma was investigated with a variety of diagnostic instruments, including a novel instrumented limiter probe. The author characterized the spatial structure of the hot-electron plasma. Details of the heating process cause the plasma to separate into two regions: a halo, consisting entirely of energetic electrons, and a core, which is dominated by cooler electrons. The plasma structure forms rapidly under the action of second-harmonic ECRH. Fundamental ECRH, which is typically applied simultaneously, is only weakly absorbed and generally does not create energetic electrons. The ECRH-generated plasma displays several loss mechanisms. Hot electrons in the halo region, with T e ∼ 30 keV, are formed by localized ECRH near the plasma boundary, and are lost through a radial process involving open magnetic-curvature-drift surfaces

  4. Hot deformation behavior and hot working characteristic of Nickel-base electron beam weldments

    International Nuclear Information System (INIS)

    Ning, Yongquan; Yao, Zekun; Guo, Hongzhen; Fu, M.W.

    2014-01-01

    Highlights: • The Hot deformation behavior of electron beam (EB) Nickel-base weldments was investigated. • The constitutive equation represented by temperature, strain rate and true strain was developed. • Processing map approach was adopted to optimize the hot forging process of EB weldments. • True strain has a great effect on the efficiency of power dissipation (η). -- Abstract: The electron beam welding (EBW) of Nickel-base superalloys was conducted, and the cylindrical compression specimens were machined from the central part of the electron beam (EB) weldments. The hot deformation behavior of EB weldments was investigated at the temperature of 960–1140 °C and the strain rate of 0.001–1.0 s −1 . The apparent activation energy of deformation was calculated to be 400 kJ/mol, and the constitutive equation that describes the flow stress as a function of strain rate and deformation temperature was proposed for modeling of the hot deformation process of EB weldments. The processing map approach was adopted to investigate the deformation mechanisms during the hot plastic deformation and to optimize the processing parameters of EB weldments. It is found that the true strain has a significant effect on the efficiency of power dissipation (η). The η value in the safe processing domain (1140 °C, 1.0 s −1 ) increases from 0.32 to 0.55. In the unsafe processing domain (1080 °C, 0.001 s −1 ), however, the η value greatly decreases with the increase of strain. When the strain is 0.40, the efficiency of power dissipation becomes negative. The flow instability is predicted to occur since the instability parameter ξ(ε) becomes negative. The hot deformation of EB weldments can be carried out safely in the domain with the strain rate range of 0.1–1.0 s −1 and the temperature range of 960–1140 °C. When the height reduction is about 50%, the optimum processing condition is (T opi : 1140 °C, ε opi : 1.0 s −1 ) with the peak efficiency of 0

  5. Hot deformation behavior and hot working characteristic of Nickel-base electron beam weldments

    Energy Technology Data Exchange (ETDEWEB)

    Ning, Yongquan, E-mail: ningke521@163.com [School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072 (China); Yao, Zekun; Guo, Hongzhen [School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072 (China); Fu, M.W. [Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong (China)

    2014-01-25

    Highlights: • The Hot deformation behavior of electron beam (EB) Nickel-base weldments was investigated. • The constitutive equation represented by temperature, strain rate and true strain was developed. • Processing map approach was adopted to optimize the hot forging process of EB weldments. • True strain has a great effect on the efficiency of power dissipation (η). -- Abstract: The electron beam welding (EBW) of Nickel-base superalloys was conducted, and the cylindrical compression specimens were machined from the central part of the electron beam (EB) weldments. The hot deformation behavior of EB weldments was investigated at the temperature of 960–1140 °C and the strain rate of 0.001–1.0 s{sup −1}. The apparent activation energy of deformation was calculated to be 400 kJ/mol, and the constitutive equation that describes the flow stress as a function of strain rate and deformation temperature was proposed for modeling of the hot deformation process of EB weldments. The processing map approach was adopted to investigate the deformation mechanisms during the hot plastic deformation and to optimize the processing parameters of EB weldments. It is found that the true strain has a significant effect on the efficiency of power dissipation (η). The η value in the safe processing domain (1140 °C, 1.0 s{sup −1}) increases from 0.32 to 0.55. In the unsafe processing domain (1080 °C, 0.001 s{sup −1}), however, the η value greatly decreases with the increase of strain. When the strain is 0.40, the efficiency of power dissipation becomes negative. The flow instability is predicted to occur since the instability parameter ξ(ε) becomes negative. The hot deformation of EB weldments can be carried out safely in the domain with the strain rate range of 0.1–1.0 s{sup −1} and the temperature range of 960–1140 °C. When the height reduction is about 50%, the optimum processing condition is (T{sub opi}: 1140 °C, ε{sub opi}: 1.0 s{sup −1}) with

  6. Equivalent circuit-level model of quantum cascade lasers with integrated hot-electron and hot-phonon effects

    Science.gov (United States)

    Yousefvand, H. R.

    2017-12-01

    We report a study of the effects of hot-electron and hot-phonon dynamics on the output characteristics of quantum cascade lasers (QCLs) using an equivalent circuit-level model. The model is developed from the energy balance equation to adopt the electron temperature in the active region levels, the heat transfer equation to include the lattice temperature, the nonequilibrium phonon rate to account for the hot phonon dynamics and simplified two-level rate equations to incorporate the carrier and photon dynamics in the active region. This technique simplifies the description of the electron-phonon interaction in QCLs far from the equilibrium condition. Using the presented model, the steady and transient responses of the QCLs for a wide range of sink temperatures (80 to 320 K) are investigated and analysed. The model enables us to explain the operating characteristics found in QCLs. This predictive model is expected to be applicable to all QCL material systems operating in pulsed and cw regimes.

  7. Size dependence investigations of hot electron cooling dynamics in metal/adsorbates nanoparticles

    International Nuclear Information System (INIS)

    Bauer, Christophe; Abid, Jean-Pierre; Girault, Hubert H.

    2005-01-01

    The size dependence of electron-phonon coupling rate has been investigated by femtosecond transient absorption spectroscopy for gold nanoparticles (NPs) wrapped in a shell of sulfate with diameter varying from 1.7 to 9.2 nm. Broad-band spectroscopy gives an overview of the complex dynamics of nonequilibrium electrons and permits the choice of an appropriate probe wavelength for studying the electron-phonon coupling dynamics. Ultrafast experiments were performed in the weak perturbation regime (less than one photon in average per nanoparticle), which allows the direct extraction of the hot electron cooling rates in order to compare different NPs sizes under the same conditions. Spectroscopic data reveals a decrease of hot electron energy loss rates with metal/adsorbates nanosystem sizes. Electron-phonon coupling time constants obtained for 9.2 nm NPs are similar to gold bulk materials (∼1 ps) whereas an increase of hot electron cooling time up to 1.9 ps is observed for sizes of 1.7 nm. This is rationalized by the domination of surface effects over size (bulk) effects. The slow hot electron cooling is attributed to the adsorbates-induced long-lived nonthermal regime, which significantly reduces the electron-phonon coupling strength (average rate of phonon emission)

  8. Numerical simulation of neutral injection in a hot-electron mirror target plasma

    International Nuclear Information System (INIS)

    Werkoff, F.; Bardet, R.; Briand, P.; Dupas, L.; Gormezano, C.; Melin, G.; Association Euratom-CEA, Centre d'Etudes Nucleaires de Grenoble, 38

    1976-01-01

    In the case of neutral injection into a hot-electron target plasma, the use of the existing Fokker-Planck codes is greatly complicated by the fact that the scale of the energies and times of the confined ions and electrons is very large. To avoid this difficulty, a simplified multi-species model is set up, in which each species is described by time-dependent density and energy equations with analytical approximations for the interactions between the species. During the neutral injection, instantaneous high values of the ambipolar potential (higher than the half value of hot-ion energy) may appear, but do not prevent hot-ion density build-up. However, the hot-electron target plasma must not be maintained for a too long time. Numerical runs are performed with typical target parameters: density 2x10 13 cm -3 , electron energy 30 keV, ion energy 400 eV, time duration during which the target density is maintained 1 ms. Hot-ion density, a few 10 14 cm -3 , can be achieved with a neutral beam of 100 A, 20 keV. (author)

  9. High frequency conductivity of hot electrons in carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Amekpewu, M., E-mail: mamek219@gmail.com [Department of Applied Physics, University for Development Studies, Navrongo (Ghana); Mensah, S.Y. [Department of Physics, College of Agriculture and Natural Sciences, U.C.C. (Ghana); Musah, R. [Department of Applied Physics, University for Development Studies, Navrongo (Ghana); Mensah, N.G. [Department of Mathematics, College of Agriculture and Natural Sciences, U.C.C. (Ghana); Abukari, S.S.; Dompreh, K.A. [Department of Physics, College of Agriculture and Natural Sciences, U.C.C. (Ghana)

    2016-05-01

    High frequency conductivity of hot electrons in undoped single walled achiral Carbon Nanotubes (CNTs) under the influence of ac–dc driven fields was considered. We investigated semi-classically Boltzmann's transport equation with and without the presence of the hot electrons’ source by deriving the current densities in CNTs. Plots of the normalized current density versus frequency of ac-field revealed an increase in both the minimum and maximum peaks of normalized current density at lower frequencies as a result of a strong injection of hot electrons. The applied ac-field plays a twofold role of suppressing the space-charge instability in CNTs and simultaneously pumping an energy for lower frequency generation and amplification of THz radiations. These have enormous promising applications in very different areas of science and technology.

  10. Surface and volume photoemission of hot electrons from plasmonic nanoantennas

    DEFF Research Database (Denmark)

    Uskov, Alexander V.; Protsenko, Igor E.; Ikhsanov, Renat S.

    2014-01-01

    We theoretically compare surface- and volume-based photoelectron emission from spherical nanoparticles, obtaining analytical expressions for the emission rate in both mechanisms. We show that the surface mechanism prevails, being unaffected by detrimental hot electron collisions.......We theoretically compare surface- and volume-based photoelectron emission from spherical nanoparticles, obtaining analytical expressions for the emission rate in both mechanisms. We show that the surface mechanism prevails, being unaffected by detrimental hot electron collisions....

  11. Hot electron plasma equilibrium and stability in the Constance B mirror experiment

    International Nuclear Information System (INIS)

    Chen, Xing.

    1988-04-01

    An experimental study of the equilibrium and macroscopic stability property of an electron cyclotron resonance heating (ECRH) generated plasma in a minimum-B mirror is presented. The Constance B mirror is a single cell quadrupole magnetic mirror in which high beta (β ≤ 0.3) hot electron plasmas (T/sub e/≅400 keV) are created with up to 4 kW of ECRH power. The plasma equilibrium profile is hollow and resembles the baseball seam geometry of the magnet which provides the confining magnetic field. This configuration coincides with the drift orbit of deeply trapped particles. The on-axis hollowness of the hot electron density profile is 50 /+-/ 10%, and the pressure profile is at least as hollow as, if not more than, the hot electron density profile. The hollow plasma equilibrium is macroscopically stable and generated in all the experimental conditions in which the machine has been operated. Small macroscopic plasma fluctuations in the range of the hot electron curvature drift frequency sometimes occur but their growth rate is small (ω/sub i//ω/sub r/ ≤ 10 -2 ) and saturate at very low level (δB//bar B/ ≤ 10 -3 ). Particle drift reversal is predicted to occur for the model pressure profile which best fits the experimental data under the typical operating conditions. No strong instability is observed when the plasma is near the drift reversal parameter regime, despite a theoretical prediction of instability under such conditions. The experiment shows that the cold electron population has no stabilizing effect to the hot electrons, which disagrees with current hot electron stability theories and results of previous maximum-B experiments. A theoretical analysis using MHD theory shows that the compressibility can stabilize a plasma with a hollowness of 20--30% in the Constance B mirror well. 57 refs

  12. Au nanoparticle-decorated silicon pyramids for plasmon-enhanced hot electron near-infrared photodetection

    Science.gov (United States)

    Qi, Zhiyang; Zhai, Yusheng; Wen, Long; Wang, Qilong; Chen, Qin; Iqbal, Sami; Chen, Guangdian; Xu, Ji; Tu, Yan

    2017-07-01

    The heterojunction between metal and silicon (Si) is an attractive route to extend the response of Si-based photodiodes into the near-infrared (NIR) region, so-called Schottky barrier diodes. Photons absorbed into a metallic nanostructure excite the surface plasmon resonances (SPRs), which can be damped non-radiatively through the creation of hot electrons. Unfortunately, the quantum efficiency of hot electron detectors remains low due to low optical absorption and poor electron injection efficiency. In this study, we propose an efficient and low-cost plasmonic hot electron NIR photodetector based on a Au nanoparticle (Au NP)-decorated Si pyramid Schottky junction. The large-area and lithography-free photodetector is realized by using an anisotropic chemical wet etching and rapid thermal annealing (RTA) of a thin Au film. We experimentally demonstrate that these hot electron detectors have broad photoresponsivity spectra in the NIR region of 1200-1475 nm, with a low dark current on the order of 10-5 A cm-2. The observed responsivities enable these devices to be competitive with other reported Si-based NIR hot electron photodetectors using perfectly periodic nanostructures. The improved performance is attributed to the pyramid surface which can enhance light trapping and the localized electric field, and the nano-sized Au NPs which are beneficial for the tunneling of hot electrons. The simple and large-area preparation processes make them suitable for large-scale thermophotovoltaic cell and low-cost NIR detection applications.

  13. High-Current Gain Two-Dimensional MoS 2 -Base Hot-Electron Transistors

    KAUST Repository

    Torres, Carlos M.

    2015-12-09

    The vertical transport of nonequilibrium charge carriers through semiconductor heterostructures has led to milestones in electronics with the development of the hot-electron transistor. Recently, significant advances have been made with atomically sharp heterostructures implementing various two-dimensional materials. Although graphene-base hot-electron transistors show great promise for electronic switching at high frequencies, they are limited by their low current gain. Here we show that, by choosing MoS2 and HfO2 for the filter barrier interface and using a noncrystalline semiconductor such as ITO for the collector, we can achieve an unprecedentedly high-current gain (α ∼ 0.95) in our hot-electron transistors operating at room temperature. Furthermore, the current gain can be tuned over 2 orders of magnitude with the collector-base voltage albeit this feature currently presents a drawback in the transistor performance metrics such as poor output resistance and poor intrinsic voltage gain. We anticipate our transistors will pave the way toward the realization of novel flexible 2D material-based high-density, low-energy, and high-frequency hot-carrier electronic applications. © 2015 American Chemical Society.

  14. High-Current Gain Two-Dimensional MoS 2 -Base Hot-Electron Transistors

    KAUST Repository

    Torres, Carlos M.; Lan, Yann Wen; Zeng, Caifu; Chen, Jyun Hong; Kou, Xufeng; Navabi, Aryan; Tang, Jianshi; Montazeri, Mohammad; Adleman, James R.; Lerner, Mitchell B.; Zhong, Yuan Liang; Li, Lain-Jong; Chen, Chii Dong; Wang, Kang L.

    2015-01-01

    The vertical transport of nonequilibrium charge carriers through semiconductor heterostructures has led to milestones in electronics with the development of the hot-electron transistor. Recently, significant advances have been made with atomically sharp heterostructures implementing various two-dimensional materials. Although graphene-base hot-electron transistors show great promise for electronic switching at high frequencies, they are limited by their low current gain. Here we show that, by choosing MoS2 and HfO2 for the filter barrier interface and using a noncrystalline semiconductor such as ITO for the collector, we can achieve an unprecedentedly high-current gain (α ∼ 0.95) in our hot-electron transistors operating at room temperature. Furthermore, the current gain can be tuned over 2 orders of magnitude with the collector-base voltage albeit this feature currently presents a drawback in the transistor performance metrics such as poor output resistance and poor intrinsic voltage gain. We anticipate our transistors will pave the way toward the realization of novel flexible 2D material-based high-density, low-energy, and high-frequency hot-carrier electronic applications. © 2015 American Chemical Society.

  15. Hot electron attenuation of direct and scattered carriers across an epitaxial Schottky interface

    NARCIS (Netherlands)

    Parui, S.; Klandermans, P. S.; Venkatesan, S.; Scheu, C.; Banerjee, T.

    2013-01-01

    Hot electron transport of direct and scattered carriers across an epitaxial NiSi2/n-Si(111) interface, for different NiSi2 thickness, is studied using ballistic electron emission microscopy (BEEM). We find the BEEM transmission for the scattered hot electrons in NiSi2 to be significantly lower than

  16. Dynamics of Pierce instability of hot electron beams

    International Nuclear Information System (INIS)

    Ignatov, A.M.; Novikov, V.N.

    1986-01-01

    On the base of a new method of numerical solution of the Vlasov equation evolution of complete function of electron distribution at the injection of hot electron beams into plasma bounded with electrodes is investigated. It is shown that despite the development of electrostatic instabilities in the system the currents can run substantially exceeding the Pierce critical current

  17. Role of hot electron transport in scintillators: A theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Huihui [SZU-NUS Collaborative Innovation Center for Optoelectronic Science and Technology, Key Lab. of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen Univ. (China); Li, Qi [Physical Sciences Division, IBM TJ Watson Research Center, Yorktown Heights, NY (United States); Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, IL (United States); Lu, Xinfu; Williams, R.T. [Department of Physics, Wake Forest University, Winston Salem, NC (United States); Qian, Yiyang [College of Engineering and Applied Science, Nanjing University (China); Wu, Yuntao [Scintillation Materials Research Center, University of Tennessee, Knoxville, TN (United States)

    2016-10-15

    Despite recent intensive study on scintillators, several fundamental questions on scintillator properties are still unknown. In this work, we use ab-initio calculations to determine the energy dependent group velocity of the hot electrons from the electronic structures of several typical scintillators. Based on the calculated group velocities and optical phonon frequencies, a Monte-Carlo simulation of hot electron transport in scintillators is carried out to calculate the thermalization time and diffusion range in selected scintillators. Our simulations provide physical insights on a recent trend of improved proportionality and light yield from mixed halide scintillators. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. Slowly moving test charge in two-electron component non-Maxwellian plasma

    International Nuclear Information System (INIS)

    Ali, S.; Eliasson, B.

    2015-01-01

    Potential distributions around a slowly moving test charge are calculated by taking into account the electron-acoustic waves in an unmagnetized plasma. Considering a neutralizing background of static positive ions, the supra-thermal hot and cold electrons are described by the Vlasov equations to account for the Kappa (power-law in velocity space) and Maxwell equilibrium distributions. Fourier analysis further leads to the derivation of electrostatic potential showing the impact of supra-thermal hot electrons. The test charge moves slowly in comparison with the hot and cold electron thermal speeds and is therefore shielded by the electrons. This gives rise to a short-range Debye-Hückel potential decaying exponentially with distance and to a far field potential decaying as inverse third power of the distance from the test charge. The results are relevant for both laboratory and space plasmas, where supra-thermal hot electrons with power-law distributions have been observed

  19. Hot-Electron Intraband Luminescence from Single Hot Spots in Noble-Metal Nanoparticle Films

    Science.gov (United States)

    Haug, Tobias; Klemm, Philippe; Bange, Sebastian; Lupton, John M.

    2015-08-01

    Disordered noble-metal nanoparticle films exhibit highly localized and stable nonlinear light emission from subdiffraction regions upon illumination by near-infrared femtosecond pulses. Such hot spot emission spans a continuum in the visible and near-infrared spectral range. Strong plasmonic enhancement of light-matter interaction and the resulting complexity of experimental observations have prevented the development of a universal understanding of the origin of light emission. Here, we study the dependence of emission spectra on excitation irradiance and provide the most direct evidence yet that the continuum emission observed from both silver and gold nanoparticle aggregate surfaces is caused by recombination of hot electrons within the conduction band. The electron gas in the emitting particles, which is effectively decoupled from the lattice temperature for the duration of emission, reaches temperatures of several thousand Kelvin and acts as a subdiffraction incandescent light source on subpicosecond time scales.

  20. Hot electron dynamics at semiconductor surfaces: Implications for quantum dot photovoltaics

    Science.gov (United States)

    Tisdale, William A., III

    Finding a viable supply of clean, renewable energy is one of the most daunting challenges facing the world today. Solar cells have had limited impact in meeting this challenge because of their high cost and low power conversion efficiencies. Semiconductor nanocrystals, or quantum dots, are promising materials for use in novel solar cells because they can be processed with potentially inexpensive solution-based techniques and because they are predicted to have novel optoelectronic properties that could enable the realization of ultra-efficient solar power converters. However, there is a lack of fundamental understanding regarding the behavior of highly-excited, or "hot," charge carriers near quantum-dot and semiconductor interfaces, which is of paramount importance to the rational design of high-efficiency devices. The elucidation of these ultrafast hot electron dynamics is the central aim of this Dissertation. I present a theoretical framework for treating the electronic interactions between quantum dots and bulk semiconductor surfaces and propose a novel experimental technique, time-resolved surface second harmonic generation (TR-SHG), for probing these interactions. I then describe a series of experimental investigations into hot electron dynamics in specific quantum-dot/semiconductor systems. A two-photon photoelectron spectroscopy (2PPE) study of the technologically-relevant ZnO(1010) surface reveals ultrafast (sub-30fs) cooling of hot electrons in the bulk conduction band, which is due to strong electron-phonon coupling in this highly polar material. The presence of a continuum of defect states near the conduction band edge results in Fermi-level pinning and upward (n-type) band-bending at the (1010) surface and provides an alternate route for electronic relaxation. In monolayer films of colloidal PbSe quantum dots, chemical treatment with either hydrazine or 1,2-ethanedithiol results in strong and tunable electronic coupling between neighboring quantum dots

  1. Study of hot electrons in a ECR ion source

    International Nuclear Information System (INIS)

    Barue, C.

    1992-12-01

    The perfecting of diagnosis connected with hot electrons of plasma, and then the behaviour of measured parameters of plasma according to parameters of source working are the purpose of this thesis. The experimental results obtained give new information on hot electrons of an ECR ion source. This thesis is divided in 4 parts: the first part presents an ECR source and the experimental configuration (ECRIS physics, minimafios GHz, diagnosis used); the second part, the diagnosis (computer code of cyclotron emission and calibration); the third part gives experimental results in continuous regime (emission cyclotron diagnosis, bremsstrahlung); the fourth part, experimental results in pulsed regime (emission cyclotron diagnosis, diamagnetism) calibration)

  2. Profile modification and hot electron temperature from resonant absorption at modest intensity

    International Nuclear Information System (INIS)

    Albritton, J.R.; Langdon, A.B.

    1980-01-01

    Resonant absorption is investigated in expanding plasmas. The momentum deposition associated with the ejection of hot electrons toward low density via wavebreaking readily exceeds that of the incident laser radiation and results in significant modification of the density profile at critical. New scaling of hot electron temperature with laser and plasma parameters is presented

  3. Coaxial Ag/ZnO/Ag nanowire for highly sensitive hot-electron photodetection

    Energy Technology Data Exchange (ETDEWEB)

    Zhan, Yaohui; Li, Xiaofeng, E-mail: xfli@suda.edu.cn; Wu, Kai; Wu, Shaolong; Deng, Jiajia [College of Physics, Optoelectronics and Energy and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province and Key Lab of Modern Optical Technologies of Education Ministry of China, Soochow University, Suzhou 215006 (China)

    2015-02-23

    Single-nanowire photodetectors (SNPDs) are mostly propelled by p-n junctions, where the detection wavelength is constrained by the band-gap width. Here, we present a simple doping-free metal/semiconductor/metal SNPD, which shows strong detection tunability without such a material constraint. The proposed hot-electron SNPD exhibits superior optical and electrical advantages, i.e., optically the coaxial design leads to a strong asymmetrical photoabsorption and results in a high unidirectional photocurrent, as desired by the hot-electron collection; electrically the hot-electrons are generated in the region very close to the barrier, facilitating the electrical transport. Rigorous calculations predict an unbiased photoresponsivity of ∼200 nA/mW.

  4. How well do time-integrated Kα images represent hot electron spatial distributions?

    Science.gov (United States)

    Ovchinnikov, V. M.; Kemp, G. E.; Schumacher, D. W.; Freeman, R. R.; Van Woerkom, L. D.

    2011-07-01

    A computational study is described, which addresses how well spatially resolved time-integrated Kα images recorded in intense laser-plasma experiments correlate with the distribution of "hot" (>1 MeV) electrons as they propagate through the target. The hot electron angular distribution leaving the laser-plasma region is critically important for many applications such as Fast Ignition or laser based x-ray sources; and Kα images are commonly used as a diagnostic. It is found that Kα images can easily mislead due to refluxing and other effects. Using the particle-in-cell code LSP, it is shown that a Kα image is not solely determined by the initial population of forward directed hot electrons, but rather also depends upon "delayed" hot electrons, and in fact continues to evolve long after the end of the laser interaction. Of particular note, there is a population of hot electrons created during the laser-plasma interaction that acquire a velocity direction opposite that of the laser and subsequently reflux off the front surface of the target, deflect when they encounter magnetic fields in the laser-plasma region, and then traverse the target in a wide spatial distribution. These delayed fast electrons create significant features in the Kα time-integrated images. Electrons refluxing from the sides and the back of the target are also found to play a significant role in forming the final Kα image. The relative contribution of these processes is found to vary depending on depth within target. These effects make efforts to find simple correlations between Kα images and, for example, Fast Ignition relevant parameters prone to error. Suggestions for future target design are provided.

  5. Operation of a novel hot-electron vertical-cavity surface-emitting laser

    Science.gov (United States)

    Balkan, Naci; O'Brien-Davies, Angela; Thoms, A. B.; Potter, Richard J.; Poolton, Nigel; Adams, Michael J.; Masum, J.; Bek, Alpan; Serpenguzel, Ali; Aydinli, Atilla; Roberts, John S.

    1998-07-01

    The hot Electron Light Emission and Lasing in Semiconductor Heterostructures devices (HELLISH-1) is novel surface emitter consisting of a GaAs quantum well, within the depletion region, on the n side of Ga1-xAlxAs p- n junction. It utilizes hot electron transport parallel to the layers and injection of hot electron hole pairs into the quantum well through a combination of mechanisms including tunnelling, thermionic emission and diffusion of `lucky' carriers. Super Radiant HELLISH-1 is an advanced structure incorporating a lower distributed Bragg reflector (DBR). Combined with the finite reflectivity of the upper semiconductor-air interface reflectivity it defines a quasi- resonant cavity enabling emission output from the top surface with a higher spectral purity. The output power has increased by two orders of magnitude and reduced the full width at half maximum (FWHM) to 20 nm. An upper DBR added to the structure defines HELLISH-VCSEL which is currently the first operational hot electron surface emitting laser and lases at room temperature with a 1.5 nm FWHM. In this work we demonstrate and compare the operation of UB-HELLISH-1 and HELLISH-VCSEL using experimental and theoretical reflectivity spectra over an extensive temperature range.

  6. Electron beam welding of aluminium components

    International Nuclear Information System (INIS)

    Maajid, Ali; Vadali, S.K.; Maury, D.K.

    2015-01-01

    Aluminium is one of the most widely used materials in industries like transportation, shipbuilding, manufacturing, aerospace, nuclear, etc. The challenges in joining of aluminium are distortion, cleanliness and quality. Main difficulties faced during fusion welding of aluminium components are removal of surface oxide layer, weld porosity, high heat input requirement, distortion, hot cracking, etc. Physical properties of aluminium such as its high thermal conductivity, high coefficient of thermal expansion, no change in colour at high temperature, large difference in the melting points of the metal and its oxide (∼ 1400 °C) compound the difficulties faced during welding. Gas Tungsten Arc Welding (GTAW), Gas Metal Arc Welding (GMAW), Plasma Arc Welding (PAW), etc are generally used in industries for fusion welding of aluminium alloys. However in case of thicker jobs the above processes are not suitable due to requirements of elaborate edge preparation, preheating of jobs, fixturing to prevent distortion, etc. Moreover, precise control over the heat input during welding and weld bead penetration is not possible with above processes. Further, if heat sensitive parts are located near the weld joint then high energy density beam welding process like Electron Beam Welding (EBW) is the best possible choice for aluminium welding.This paper discusses EB welding of aluminium components, typical geometry of components, selection/optimization of welding parameters, problems faced during standardization of welding and process parameters and their remedies etc.

  7. Hard x-ray measurements of the hot-electron rings in EBT-S

    International Nuclear Information System (INIS)

    Hillis, D.L.

    1982-06-01

    A thorough understanding of the hot electron rings in ELMO Bumpy Torus-Scale (EBT-S) is essential to the bumpy torus concept of plasma production, since the rings provide bulk plasma stability. The hot electrons are produced via electron cyclotron resonant heating using a 28-GHz cw gyrotron, which has operated up to power levels of 200 kW. The parameters of the energetic electron rings are studied via hard x-ray measurement techniques and with diamagnetic pickup coils. The hard x-ray measurements have used collimated NaI(Tl) detectors to determine the electron temperature T/sub e/ and electron density n/sub e/ for the hot electron annulus. Typical values of T/sub e/ are 400 to 500 keV and of n/sub e/ 2 to 5 x 10 11 cm -3 . The total stored energy of a single energetic electron ring as measured by diamagnetic pickup loops approaches approx. 40 J and is in good agreement with that deduced from hard x-ray measurements. By combining the experimental measurements from hard x-rays and the diamagnetic loops, an estimate can be obtained for the volume of a single hot electron ring. The ring volume is determined to be approx. 2.2 litres, and this volume remains approximately constant over the T-mode operating regime. Finally, the power in the electrons scattered out of the ring is measured indirectly by measuring the x-ray radiation produced when those electrons strike the chamber walls. The variation of this radiation with increasing microwave power levels is found to be consistent with classical scattering estimates

  8. Plasmonically enhanced hot electron based photovoltaic device.

    Science.gov (United States)

    Atar, Fatih B; Battal, Enes; Aygun, Levent E; Daglar, Bihter; Bayindir, Mehmet; Okyay, Ali K

    2013-03-25

    Hot electron photovoltaics is emerging as a candidate for low cost and ultra thin solar cells. Plasmonic means can be utilized to significantly boost device efficiency. We separately form the tunneling metal-insulator-metal (MIM) junction for electron collection and the plasmon exciting MIM structure on top of each other, which provides high flexibility in plasmonic design and tunneling MIM design separately. We demonstrate close to one order of magnitude enhancement in the short circuit current at the resonance wavelengths.

  9. Significance of fundamental processes of radiation chemistry in hot atom chemical processes: electron thermalization

    International Nuclear Information System (INIS)

    Nishikawa, M.

    1984-01-01

    The author briefly reviews the current understanding of the course of electron thermalization. An outline is given of the physical picture without going into mathematical details. The analogy of electron thermalization with hot atom processes is taken as guiding principle in this paper. Content: secondary electrons (generation, track structure, yields); thermalization (mechanism, time, spatial distribution); behaviour of hot electrons. (Auth.)

  10. Simulations of Electron Transport in Laser Hot Spots

    International Nuclear Information System (INIS)

    Brunner, S.; Valeo, E.

    2001-01-01

    Simulations of electron transport are carried out by solving the Fokker-Planck equation in the diffusive approximation. The system of a single laser hot spot, with open boundary conditions, is systematically studied by performing a scan over a wide range of the two relevant parameters: (1) Ratio of the stopping length over the width of the hot spot. (2) Relative importance of the heating through inverse Bremsstrahlung compared to the thermalization through self-collisions. As for uniform illumination [J.P. Matte et al., Plasma Phys. Controlled Fusion 30 (1988) 1665], the bulk of the velocity distribution functions (VDFs) present a super-Gaussian dependence. However, as a result of spatial transport, the tails are observed to be well represented by a Maxwellian. A similar dependence of the distributions is also found for multiple hot spot systems. For its relevance with respect to stimulated Raman scattering, the linear Landau damping of the electron plasma wave is estimated for such VD Fs. Finally, the nonlinear Fokker-Planck simulations of the single laser hot spot system are also compared to the results obtained with the linear non-local hydrodynamic approach [A.V. Brantov et al., Phys. Plasmas 5 (1998) 2742], thus providing a quantitative limit to the latter method: The hydrodynamic approach presents more than 10% inaccuracy in the presence of temperature variations of the order delta T/T greater than or equal to 1%, and similar levels of deformation of the Gaussian shape of the Maxwellian background

  11. Efficient, Broadband and Wide-Angle Hot-Electron Transduction using Metal-Semiconductor Hyperbolic Metamaterials

    KAUST Repository

    Sakhdari, Maryam

    2016-05-20

    Hot-electron devices are emerging as promising candidates for the transduction of optical radiation into electrical current, as they enable photodetection and solar/infrared energy harvesting at sub-bandgap wavelengths. Nevertheless, poor photoconversion quantum yields and low bandwidth pose fundamental challenge to fascinating applications of hot-electron optoelectronics. Based on a novel hyperbolic metamaterial (HMM) structure, we theoretically propose a vertically-integrated hot-electron device that can efficiently couple plasmonic excitations into electron flows, with an external quantum efficiency approaching the physical limit. Further, this metamaterial-based device can have a broadband and omnidirectional response at infrared and visible wavelengths. We believe that these findings may shed some light on designing practical devices for energy-efficient photodetection and energy harvesting beyond the bandgap spectral limit.

  12. Enhanced energy deposition symmetry by hot electron transport

    International Nuclear Information System (INIS)

    Wilson, D.; Mack, J.; Stover, E.; VanHulsteyn, D.; McCall, G.; Hauer, A.

    1981-01-01

    High energy electrons produced by resonance absorption carry the CO 2 laser energy absorbed in a laser fusion pellet. The symmetrization that can be achieved by lateral transport of the hot electrons as they deposit their energy is discussed. A K/sub α/ experiment shows a surprising symmetrization of energy deposition achieved by adding a thin layer of plastic to a copper sphere. Efforts to numerically model this effect are described

  13. Three-dimensional hot electron photovoltaic device with vertically aligned TiO2 nanotubes.

    Science.gov (United States)

    Goddeti, Kalyan C; Lee, Changhwan; Lee, Young Keun; Park, Jeong Young

    2018-05-09

    Titanium dioxide (TiO 2 ) nanotubes with vertically aligned array structures show substantial advantages in solar cells as an electron transport material that offers a large surface area where charges travel linearly along the nanotubes. Integrating this one-dimensional semiconductor material with plasmonic metals to create a three-dimensional plasmonic nanodiode can influence solar energy conversion by utilizing the generated hot electrons. Here, we devised plasmonic Au/TiO 2 and Ag/TiO 2 nanodiode architectures composed of TiO 2 nanotube arrays for enhanced photon absorption, and for the subsequent generation and capture of hot carriers. The photocurrents and incident photon to current conversion efficiencies (IPCE) were obtained as a function of photon energy for hot electron detection. We observed enhanced photocurrents and IPCE using the Ag/TiO 2 nanodiode. The strong plasmonic peaks of the Au and Ag from the IPCE clearly indicate an enhancement of the hot electron flux resulting from the presence of surface plasmons. The calculated electric fields and the corresponding absorbances of the nanodiode using finite-difference time-domain simulation methods are also in good agreement with the experimental results. These results show a unique strategy of combining a hot electron photovoltaic device with a three-dimensional architecture, which has the clear advantages of maximizing light absorption and a metal-semiconductor interface area.

  14. Non-equilibrium between ions and electrons inside hot spots from National Ignition Facility experiments

    Directory of Open Access Journals (Sweden)

    Zhengfeng Fan

    2017-01-01

    Full Text Available The non-equilibrium between ions and electrons in the hot spot can relax the ignition conditions in inertial confinement fusion [Fan et al., Phys. Plasmas 23, 010703 (2016], and obvious ion-electron non-equilibrium could be observed by our simulations of high-foot implosions when the ion-electron relaxation is enlarged by a factor of 2. On the other hand, in many shots of high-foot implosions on the National Ignition Facility, the observed X-ray enhancement factors due to ablator mixing into the hot spot are less than unity assuming electrons and ions have the same temperature [Meezan et al., Phys. Plasmas 22, 062703 (2015], which is not self-consistent because it can lead to negative ablator mixing into the hot spot. Actually, this non-consistency implies ion-electron non-equilibrium within the hot spot. From our study, we can infer that ion-electron non-equilibrium exists in high-foot implosions and the ion temperature could be ∼9% larger than the equilibrium temperature in some NIF shots.

  15. High-frequency microinstabilities in hot-electron plasmas

    International Nuclear Information System (INIS)

    Chen, Y.J.; Nevins, W.M.; Smith, G.R.

    1981-01-01

    Instabilities with frequencies in the neighborhood of the electron cyclotron frequency are of interest in determining stable operating regimes of hot-electron plasmas in EBT devices and in tandem mirrors. Previous work used model distributions significantly different than those suggested by recent Fokker-Planck studies. We use much more realistic model distributions in a computer code that solves the full electromagnetic dispersion relation governing longitudinal and transverse waves in a uniform plasma. We allow for an arbitrary direction of wave propagation. Results for the whistler and upper-hybrid loss-cone instabilities are presented

  16. Hot electron spatial distribution under presence of laser light self-focusing in over-dense plasmas

    International Nuclear Information System (INIS)

    Tanimoto, T; Yabuuchi, T; Habara, H; Kondo, K; Kodama, R; Mima, K; Tanaka, K A; Lei, A L

    2008-01-01

    In fast ignition for laser thermonuclear fusion, an ultra intense laser (UIL) pulse irradiates an imploded plasma in order to fast-heat a high-density core with hot electrons generated in laser-plasma interactions. An UIL pulse needs to make plasma channel via laser self-focusing and to propagate through the corona plasma to reach close enough to the core. Hot electrons are used for heating the core. Therefore the propagation of laser light in the high-density plasma region and spatial distribution of hot electron are important in issues in order to study the feasibility of this scheme. We measure the spatial distribution of hot electron when the laser light propagates into the high-density plasma region by self-focusing

  17. Specular Reflectivity and Hot-Electron Generation in High-Contrast Relativistic Laser-Plasma Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, Gregory Elijah [The Ohio State Univ., Columbus, OH (United States)

    2013-01-01

    Ultra-intense laser (> 1018 W/cm2) interactions with matter are capable of producing relativistic electrons which have a variety of applications in state-of-the-art scientific and medical research conducted at universities and national laboratories across the world. Control of various aspects of these hot-electron distributions is highly desired to optimize a particular outcome. Hot-electron generation in low-contrast interactions, where significant amounts of under-dense pre-plasma are present, can be plagued by highly non-linear relativistic laser-plasma instabilities and quasi-static magnetic field generation, often resulting in less than desirable and predictable electron source characteristics. High-contrast interactions offer more controlled interactions but often at the cost of overall lower coupling and increased sensitivity to initial target conditions. An experiment studying the differences in hot-electron generation between high and low-contrast pulse interactions with solid density targets was performed on the Titan laser platform at the Jupiter Laser Facility at Lawrence Livermore National Laboratory in Livermore, CA. To date, these hot-electrons generated in the laboratory are not directly observable at the source of the interaction. Instead, indirect studies are performed using state-of-the-art simulations, constrained by the various experimental measurements. These measurements, more-often-than-not, rely on secondary processes generated by the transport of these electrons through the solid density materials which can susceptible to a variety instabilities and target material/geometry effects. Although often neglected in these types of studies, the specularly reflected light can provide invaluable insight as it is directly influenced by the interaction. In this thesis, I address the use of (personally obtained) experimental specular reflectivity measurements to indirectly study hot-electron generation in the context of high-contrast, relativistic

  18. Superconducting cuprate heterostructures for hot electron bolometers

    Science.gov (United States)

    Wen, B.; Yakobov, R.; Vitkalov, S. A.; Sergeev, A.

    2013-11-01

    Transport properties of the resistive state of quasi-two dimensional superconducting heterostructures containing ultrathin La2-xSrxCuO4 layers synthesized using molecular beam epitaxy are studied. The electron transport exhibits strong deviation from Ohm's law, δV ˜γI3, with a coefficient γ(T) that correlates with the temperature variation of the resistivity dρ /dT. Close to the normal state, analysis of the nonlinear behavior in terms of electron heating yields an electron-phonon thermal conductance per unit area ge -ph≈1 W/K cm2 at T = 20 K, one-two orders of magnitude smaller than in typical superconductors. This makes superconducting LaSrCuO heterostructures to be attractive candidate for the next generation of hot electron bolometers with greatly improved sensitivity.

  19. Superconducting cuprate heterostructures for hot electron bolometers

    International Nuclear Information System (INIS)

    Wen, B.; Yakobov, R.; Vitkalov, S. A.; Sergeev, A.

    2013-01-01

    Transport properties of the resistive state of quasi-two dimensional superconducting heterostructures containing ultrathin La 2−x Sr x CuO 4 layers synthesized using molecular beam epitaxy are studied. The electron transport exhibits strong deviation from Ohm's law, δV∼γI 3 , with a coefficient γ(T) that correlates with the temperature variation of the resistivity dρ/dT. Close to the normal state, analysis of the nonlinear behavior in terms of electron heating yields an electron-phonon thermal conductance per unit area g e−ph ≈1 W/K cm 2 at T = 20 K, one-two orders of magnitude smaller than in typical superconductors. This makes superconducting LaSrCuO heterostructures to be attractive candidate for the next generation of hot electron bolometers with greatly improved sensitivity

  20. Reduction of adhesive stain defect in flexible printed circuit board on hot pressing process: a case study of electronic component factory

    Directory of Open Access Journals (Sweden)

    Sakulkaew Srisang

    2014-09-01

    Full Text Available The objective of this research is a reduction of an adhesive stain defect in flexible printed circuit board in hot pressing process, the electronic factory. The manufacturing have been processing by sheet type of products with ninety-six pieces of flexible printed circuit boards. Causes of the problem include the before and internal hot pressing process. In process beginning times, the most right row of products between the cooling plate and the hot pressing machine has temperature 71.2◦C that is higher than glass transition temperature (Tg 60◦C. Those products’ temperature lead to evaporate a polyimide adhesive before hot pressing process beginning. The internal hot pressing process include the preheat times and the pressure time. In the preheat time the problem is a gap between lower and upper plate, was under specification(Under 1 mm and leaded to adhesive polyimide stain. In the actuality this time requires temperature and low pressure that mean a gap within 1 – 2 mm (between lower and upper plate. In pressure times the hot pressing plate surface is not flat and products are pressed by insufficient force that it lead to generate an adhesive stain on flexible printed circuit boards. That force is measured by the pre-scale paper and a result, RGB color, is provided. And then color density (From standard color sample and RGB color (From pre-scale paper is found out the relation by Photoshop program and multiple regression theory using. The formula is applied to compare with defect so as to find out the suitable color density (Defects reducing. The solving solutions is provided including the gap reduced adjustment between cooling plate and hot pressing machine before hot pressing process, the plate adjustment within specification in the preheat time and the pressing plate polishing in the pressure time. Results of study and solving are provide defect reduction from 24.4 percentage to 7.2 percentage of total study product.

  1. Reduction of adhesive stain defect in flexible printed circuit board on hot pressing process: A case study of electronic component factory

    Directory of Open Access Journals (Sweden)

    Sakulkaew Srisang

    2015-03-01

    Full Text Available The objective of this research is a reduction of an adhesive stain defect in flexible printed circuit board in hot pressing process, the electronic factory. The manufacturing have been processing by sheet type of products with ninety-six pieces of flexible printed circuit boards. Causes of the problem include the before and internal hot pressing process. In process beginning times, the most right row of products between the cooling plate and the hot pressing machine has temperature 71.2◦C that is higher than glass transition temperature (Tg 60◦C. Those products’ temperature lead to evaporate a polyimide adhesive before hot pressing process beginning. The internal hot pressing process include the preheat times and the pressure time. In the preheat time the problem is a gap between lower and upper plate, was under specification (Under 1 mm and leaded to adhesive polyimide stain. In the actuality this time requires temperature and low pressure that mean a gap within 1 – 2 mm (between lower and upper plate. In pressure times the hot pressing plate surface is not flat and products are pressed by insufficient force that it lead to generate an adhesive stain on flexible printed circuit boards. That force is measured by the pre-scale paper and a result, RGB color, is provided. And then color density (From standard color sample and RGB color (From pre-scale paper is found out the relation by Photoshop program and multiple regression theory using. The formula is applied to compare with defect so as to find out the suitable color density (Defects reducing. The solving solutions is provided including the gap reduced adjustment between cooling plate and hot pressing machine before hot pressing process, the plate adjustment within specification in the preheat time and the pressing plate polishing in the pressure time. Results of study and solving are provide defect reduction from 24.4 percentage to 7.2 percentage of total study product.

  2. Electronic components and systems

    CERN Document Server

    Dennis, W H

    2013-01-01

    Electronic Components and Systems focuses on the principles and processes in the field of electronics and the integrated circuit. Covered in the book are basic aspects and physical fundamentals; different types of materials involved in the field; and passive and active electronic components such as capacitors, inductors, diodes, and transistors. Also covered in the book are topics such as the fabrication of semiconductors and integrated circuits; analog circuitry; digital logic technology; and microprocessors. The monograph is recommended for beginning electrical engineers who would like to kn

  3. Hot Electron Nanoscopy and Spectroscopy (HENs)

    KAUST Repository

    Giugni, Andrea; Torre, Bruno; Allione, Marco; Perozziello, Gerardo; Candeloro, Patrizio; Di Fabrizio, Enzo M.

    2017-01-01

    This chapter includes a brief description of different laser coupling methods with guided surface plasmon polariton (SPP) modes at the surface of a cone. It shows some devices, their electromagnetic simulations, and their optical characterization. A theoretical section illustrates the optical and quantum description of the hot charge generation rate as obtained for the SPP propagation along the nanocone in adiabatic compression. The chapter also shows some experimental results concerning the application of the hot electron nanoscopy and spectroscopy (HENs) in the so-called Schottky configuration, highlighting the sensitivity and the nanoscale resolution of the technique. The comparison with Kelvin probe and other electric atomic force microscopy (AFM) techniques points out the intrinsic advantages of the HENs. In the end, some further insights are given about the possibility of exploiting HENs with a pulsed laser at the femtosecond time scale without significant pulse broadening and dispersion.

  4. Hot Electron Nanoscopy and Spectroscopy (HENs)

    KAUST Repository

    Giugni, Andrea

    2017-08-17

    This chapter includes a brief description of different laser coupling methods with guided surface plasmon polariton (SPP) modes at the surface of a cone. It shows some devices, their electromagnetic simulations, and their optical characterization. A theoretical section illustrates the optical and quantum description of the hot charge generation rate as obtained for the SPP propagation along the nanocone in adiabatic compression. The chapter also shows some experimental results concerning the application of the hot electron nanoscopy and spectroscopy (HENs) in the so-called Schottky configuration, highlighting the sensitivity and the nanoscale resolution of the technique. The comparison with Kelvin probe and other electric atomic force microscopy (AFM) techniques points out the intrinsic advantages of the HENs. In the end, some further insights are given about the possibility of exploiting HENs with a pulsed laser at the femtosecond time scale without significant pulse broadening and dispersion.

  5. Amplification of hot electron flow by the surface plasmon effect on metal–insulator–metal nanodiodes

    International Nuclear Information System (INIS)

    Lee, Changhwan; Nedrygailov, Ievgen I; Keun Lee, Young; Lee, Hyosun; Young Park, Jeong; Ahn, Changui; Jeon, Seokwoo

    2015-01-01

    Au–TiO_2–Ti nanodiodes with a metal–insulator–metal structure were used to probe hot electron flows generated upon photon absorption. Hot electrons, generated when light is absorbed in the Au electrode of the nanodiode, can travel across the TiO_2, leading to a photocurrent. Here, we demonstrate amplification of the hot electron flow by (1) localized surface plasmon resonance on plasmonic nanostructures fabricated by annealing the Au–TiO_2–Ti nanodiodes, and (2) reducing the thickness of the TiO_2. We show a correlation between changes in the morphology of the Au electrodes caused by annealing and amplification of the photocurrent. Based on the exponential dependence of the photocurrent on TiO_2 thickness, the transport mechanism for the hot electrons across the nanodiodes is proposed. (paper)

  6. Large scale features of the hot component of the interstellar medium

    International Nuclear Information System (INIS)

    Garmire, G.P.

    1983-01-01

    The interstellar medium contains identifiable hot plasma clouds occupying up to about 35% of the volume of the local galactic disc. The temperature of these clouds is not uniform but ranges from 10 5 up to 4 x 10 6 K. Besides the high temperature which places the emission spectrum in the soft X-ray band, the implied pressure of the hot plasma compared to the cooler gas reveals the importance of this component in determining the motions and evolution of the cooler gas in the disc, as well as providing a source of hot gas which may extend above the galactic disc to form a corona. The author presents data from the A-2 soft X-ray experiment on the HEAO-1 spacecraft concerning the large scale features of this gas. These features are interpreted in terms of the late phases of supernovae expansion, multiple supernovae and the possible creation of a hot halo surrounding the region of the galactic nucleus. (Auth.)

  7. Monte Carlo study of electron-plasmon scattering effects on hot electron transport in GaAs

    International Nuclear Information System (INIS)

    Popov, V.V.; Bagaeva, T.Yu.; Solodkaya, T.I.

    1994-07-01

    It is shown using Monte Carlo simulation that electron-plasmon scattering affects substantially the hot-electron energy distribution function and transport properties in bulk GaAs. However, this effect is found to be much less than that predicted in earlier paper of other authors. (author). 5 refs, 7 figs

  8. Plasma relaxation of cold electrons and hot ions

    International Nuclear Information System (INIS)

    Potapenko, I.F.; Sakanaka, P.H.

    1996-01-01

    The relaxation process of a space uniform plasma composed of cold electrons and one species of hot ions studied numerically. Special attention has been paid to the deviation of relaxation from the classical picture which is characterized by a weakly non-isothermic situation. (author). 6 refs., 2 figs

  9. Production of hot electrons in mirror systems associated with ECR heating with longitudinal input of microwaves

    International Nuclear Information System (INIS)

    Zhil'tsov, V.A.; Skovoroda, A.A.; Timofeev, A.V.; Kharitonov, K.Yu.; Shcherbakov, A.G.

    1991-01-01

    Almost all experiments on ECR plasma heating are accompanied by the formation of hot electrons (i.e., electrons with energy substantially greater than the average of the bulk population). In mirror systems these electrons may determine the basic energy content (β) of the plasma. In this paper, results are presented from experimental measurements of the hot electron population resulting from ECR heating of the plasma in OGRA-4. A theoretical model is developed which describes the hot electron dynamics and the propagation of electromagnetic oscillations in the plasma self-consistently. The results obtained with this model are in agreement with experimental data

  10. Imaging Plasmon Hybridization of Fano Resonances via Hot-Electron-Mediated Absorption Mapping.

    Science.gov (United States)

    Simoncelli, Sabrina; Li, Yi; Cortés, Emiliano; Maier, Stefan A

    2018-05-04

    The inhibition of radiative losses in dark plasmon modes allows storing electromagnetic energy more efficiently than in far-field excitable bright-plasmon modes. As such, processes benefiting from the enhanced absorption of light in plasmonic materials could also take profit of dark plasmon modes to boost and control nanoscale energy collection, storage, and transfer. We experimentally probe this process by imaging with nanoscale precision the hot-electron driven desorption of thiolated molecules from the surface of gold Fano nanostructures, investigating the effect of wavelength and polarization of the incident light. Spatially resolved absorption maps allow us to show the contribution of each element of the nanoantenna in the hot-electron driven process and their interplay in exciting a dark plasmon mode. Plasmon-mode engineering allows control of nanoscale reactivity and offers a route to further enhance and manipulate hot-electron driven chemical reactions and energy-conversion and transfer at the nanoscale.

  11. Interlayer electron-hole pair multiplication by hot carriers in atomic layer semiconductor heterostructures

    Science.gov (United States)

    Barati, Fatemeh; Grossnickle, Max; Su, Shanshan; Lake, Roger; Aji, Vivek; Gabor, Nathaniel

    Two-dimensional heterostructures composed of atomically thin transition metal dichalcogenides provide the opportunity to design novel devices for the study of electron-hole pair multiplication. We report on highly efficient multiplication of interlayer electron-hole pairs at the interface of a tungsten diselenide / molybdenum diselenide heterostructure. Electronic transport measurements of the interlayer current-voltage characteristics indicate that layer-indirect electron-hole pairs are generated by hot electron impact excitation. Our findings, which demonstrate an efficient energy relaxation pathway that competes with electron thermalization losses, make 2D semiconductor heterostructures viable for a new class of hot-carrier energy harvesting devices that exploit layer-indirect electron-hole excitations. SHINES, an Energy Frontier Research Center funded by the U.S. Department of Energy, Air Force Office of Scientific Research.

  12. Proton beam shaped by “particle lens” formed by laser-driven hot electrons

    International Nuclear Information System (INIS)

    Zhai, S. H.; Shen, B. F.; Wang, W. P.; Zhang, H.; Zhang, L. G.; Huang, S.; Xu, Z. Z.; He, S. K.; Lu, F.; Zhang, F. Q.; Deng, Z. G.; Dong, K. G.; Wang, S. Y.; Zhou, K. N.; Xie, N.; Wang, X. D.; Liu, H. J.; Zhao, Z. Q.; Gu, Y. Q.; Zhang, B. H.

    2016-01-01

    Two-dimensional tailoring of a proton beam is realized by a “particle lens” in our experiment. A large quantity of electrons, generated by an intense femtosecond laser irradiating a polymer target, produces an electric field strong enough to change the trajectory and distribution of energetic protons flying through the electron area. The experiment shows that a strip pattern of the proton beam appears when hot electrons initially converge inside the plastic plate. Then the shape of the proton beam changes to a “fountain-like” pattern when these hot electrons diffuse after propagating a distance.

  13. Experimental study on energy distribution of the hot electrons generated by femtosecond laser interacting with solid targets

    International Nuclear Information System (INIS)

    Gu Yuqiu; Zheng Zhijian; Zhou Weimin; Wen Tianshu; Chunyu Shutai; Cai Dafeng; Sichuan Univ., Chengdu; Neijiang Teachers College, Neijiang; Jiao Chunye; Chen Hao; Sichuan Univ., Chengdu; Yang Xiangdong

    2005-01-01

    This paper reports the results of the experiment of hot electron energy distribution during the femtosecond laser-solid target interaction. The hot electrons formed an anisotropic energy distribution. In the direction of the target normal, the energy spectrum of the hot electron was a Maxwellian-like distribution with an effective temperature of 206 keV, which was due to the resonance absorption. In the direction of the specular reflection of laser, there appeared a local plateau of hot electron energy spectrum at the beginning and then it was decreased gradually, which maybe produced by several acceleration mechanisms. The effective temperature and the yield of hot electrons in the direction of the target normal is larger than those in the direction of the specular reflection of laser, which proves that the resonance absorption mechanism is more effective than others. (authors)

  14. Electron-electron scattering-induced channel hot electron injection in nanoscale n-channel metal-oxide-semiconductor field-effect-transistors with high-k/metal gate stacks

    International Nuclear Information System (INIS)

    Tsai, Jyun-Yu; Liu, Kuan-Ju; Lu, Ying-Hsin; Liu, Xi-Wen; Chang, Ting-Chang; Chen, Ching-En; Ho, Szu-Han; Tseng, Tseung-Yuen; Cheng, Osbert; Huang, Cheng-Tung; Lu, Ching-Sen

    2014-01-01

    This work investigates electron-electron scattering (EES)-induced channel hot electron (CHE) injection in nanoscale n-channel metal-oxide-semiconductor field-effect-transistors (n-MOSFETs) with high-k/metal gate stacks. Many groups have proposed new models (i.e., single-particle and multiple-particle process) to well explain the hot carrier degradation in nanoscale devices and all mechanisms focused on Si-H bond dissociation at the Si/SiO 2 interface. However, for high-k dielectric devices, experiment results show that the channel hot carrier trapping in the pre-existing high-k bulk defects is the main degradation mechanism. Therefore, we propose a model of EES-induced CHE injection to illustrate the trapping-dominant mechanism in nanoscale n-MOSFETs with high-k/metal gate stacks.

  15. Formation of stable, high-beta, relativistic-electron plasmas using electron cyclotron heating

    International Nuclear Information System (INIS)

    Guest, G.E.; Miller, R.L.

    1988-01-01

    A one-dimensional, steady-state, relativistic Fokker-Planck model of electron cyclotron heating (ECH) is used to analyse the heating kinetics underlying the formation of the two-component hot-electron plasmas characteristic of ECH in magnetic mirror configurations. The model is first applied to the well diagnosed plasmas obtained in SM-1 and is then used to simulate the effective generation of relativistic electrons by upper off-resonant heating (UORH), as demonstrated empirically in ELMO. The characteristics of unstable whistler modes and cyclotron maser modes are then determined for two-component hot-electron plasmas sustained by UORH. Cyclotron maser modes are shown to be strongly suppressed by the colder background electron species, while the growth rates of whistler modes are reduced by relativistic effects to levels that may render them unobservable, provided the hot-electron pressure anisotropy is below an energy dependent threshold. (author). 29 refs, 10 figs, 1 tab

  16. Modification of the Absorption Edge of GaAs Arising from Hot-Electron Effects

    DEFF Research Database (Denmark)

    McGroddy, J. C.; Christensen, Ove

    1973-01-01

    We have observed a large enhancement of the electric-field-induced optical absorption arising from hot-electron effects in n-type GaAs at 77 K. The magnitude and field dependence of the enhancement can be approximately accounted for by a theory attributing the effect to broadening of the final...... states of the optical transitions by interaction with the nonequilibrium optical phonons produced by the hot electrons....

  17. Component reliability for electronic systems

    CERN Document Server

    Bajenescu, Titu-Marius I

    2010-01-01

    The main reason for the premature breakdown of today's electronic products (computers, cars, tools, appliances, etc.) is the failure of the components used to build these products. Today professionals are looking for effective ways to minimize the degradation of electronic components to help ensure longer-lasting, more technically sound products and systems. This practical book offers engineers specific guidance on how to design more reliable components and build more reliable electronic systems. Professionals learn how to optimize a virtual component prototype, accurately monitor product reliability during the entire production process, and add the burn-in and selection procedures that are the most appropriate for the intended applications. Moreover, the book helps system designers ensure that all components are correctly applied, margins are adequate, wear-out failure modes are prevented during the expected duration of life, and system interfaces cannot lead to failure.

  18. 3-D inelastic analysis methods for hot section components. Volume 2: Advanced special functions models

    Science.gov (United States)

    Wilson, R. B.; Banerjee, P. K.

    1987-01-01

    This Annual Status Report presents the results of work performed during the third year of the 3-D Inelastic Analysis Methods for Hot Sections Components program (NASA Contract NAS3-23697). The objective of the program is to produce a series of computer codes that permit more accurate and efficient three-dimensional analyses of selected hot section components, i.e., combustor liners, turbine blades, and turbine vanes. The computer codes embody a progression of mathematical models and are streamlined to take advantage of geometrical features, loading conditions, and forms of material response that distinguish each group of selected components.

  19. Plasmonic photocatalytic reactions enhanced by hot electrons in a one-dimensional quantum well

    Directory of Open Access Journals (Sweden)

    H. J. Huang

    2015-11-01

    Full Text Available The plasmonic endothermic oxidation of ammonium ions in a spinning disk reactor resulted in light energy transformation through quantum hot charge carriers (QHC, or quantum hot electrons, during a chemical reaction. It is demonstrated with a simple model that light of various intensities enhance the chemical oxidization of ammonium ions in water. It was further observed that light illumination, which induces the formation of plasmons on a platinum (Pt thin film, provided higher processing efficiency compared with the reaction on a bare glass disk. These induced plasmons generate quantum hot electrons with increasing momentum and energy in the one-dimensional quantum well of a Pt thin film. The energy carried by the quantum hot electrons provided the energy needed to catalyze the chemical reaction. The results indicate that one-dimensional confinement in spherical coordinates (i.e., nanoparticles is not necessary to provide an extra excited state for QHC generation; an 8 nm Pt thin film for one-dimensional confinement in Cartesian coordinates can also provide the extra excited state for the generation of QHC.

  20. Penetration length-dependent hot electrons in the field emission from ZnO nanowires

    Science.gov (United States)

    Chen, Yicong; Song, Xiaomeng; Li, Zhibing; She, Juncong; Deng, Shaozhi; Xu, Ningsheng; Chen, Jun

    2018-01-01

    In the framework of field emission, whether or not hot electrons can form in the semiconductor emitters under a surface penetration field is of great concern, which will provide not only a comprehensive physical picture of field emission from semiconductor but also guidance on how to improve device performance. However, apart from some theoretical work, its experimental evidence has not been reported yet. In this article, the field penetration length-dependent hot electrons were observed in the field emission of ZnO nanowires through the in-situ study of its electrical and field emission characteristic before and after NH3 plasma treatment in an ultrahigh vacuum system. After the treatment, most of the nanowires have an increased carrier density but reduced field emission current. The raised carrier density was caused by the increased content of oxygen vacancies, while the degraded field emission current was attributed to the lower kinetic energy of hot electrons caused by the shorter penetration length. All of these results suggest that the field emission properties of ZnO nanowires can be optimized by modifying their carrier density to balance both the kinetic energy of field induced hot electrons and the limitation of saturated current under a given field.

  1. Ignition conditions relaxation for central hot-spot ignition with an ion-electron non-equilibrium model

    Science.gov (United States)

    Fan, Zhengfeng; Liu, Jie

    2016-10-01

    We present an ion-electron non-equilibrium model, in which the hot-spot ion temperature is higher than its electron temperature so that the hot-spot nuclear reactions are enhanced while energy leaks are considerably reduced. Theoretical analysis shows that the ignition region would be significantly enlarged in the hot-spot rhoR-T space as compared with the commonly used equilibrium model. Simulations show that shocks could be utilized to create and maintain non-equilibrium conditions within the hot spot, and the hot-spot rhoR requirement is remarkably reduced for achieving self-heating. In NIF high-foot implosions, it is observed that the x-ray enhancement factors are less than unity, which is not self-consistent and is caused by assuming Te =Ti. And from this non-consistency, we could infer that ion-electron non-equilibrium exists in the high-foot implosions and the ion temperature could be 9% larger than the equilibrium temperature.

  2. Hot-electrons-induced ultrafast demagnitization in Co/Pt multilayers

    NARCIS (Netherlands)

    Bergeard, N.; Hehn, M.; Mangin, S.; Lengaigne, G.; Montaigne, F.; Lalieu, M. L. M.; Koopmans, B.; Malinowski, G.

    2016-01-01

    Using specially engineered structures to tailor the optical absorption in a metallic multilayer, we analyze the magnetization dynamics of a Co/Pt multilayer buried below a thick Cu layer. We demonstrate that hot electrons alone can very efficiently induce ultrafast demagnetization. Simulations based

  3. Ultrafast Hot Electron Induced Phase Transitions in Vanadium Dioxide

    Directory of Open Access Journals (Sweden)

    Haglund R. F.

    2013-03-01

    Full Text Available The Au/Cr/VO2/Si system was investigated in pump–probe experiments. Hot-electrons generated in the Au were found to penetrate into the underlying VO2 and couple with its lattice inducing a semiconductor-to-metal phase transition in ~2 picoseconds.

  4. Finite orbit analysis for long wavelength modes in a plasma with a hot component

    International Nuclear Information System (INIS)

    Hammer, J.H.; Berk, H.L.

    1985-01-01

    The z-pinch model is used to calculate finite Larmor radius effects of a plasma with a hot component plasma annulus. The equations are analyzed for layer modes and the finite Larmor radius stabilization condition is calculated. Stability requires k 2 rho/sub h/ 2 Rβ/sub h//Δ greater than or equal to 1, where k is the wavenumber in the z-direction, rho/sub h/ the hot species Larmor radius, β/sub h/ the hot particle beta and Δ the thickness of the pressure profile. In addition a new instability is found due to the interaction of the precessional modes associated with inner and outer edges of the hot particle pressure profile

  5. A test system for electronics components of the PANDA MVD

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Alessandra; Stockmanns, Tobias; Ritman, James [Forschungszentrum Juelich (Germany); Collaboration: PANDA-Collaboration

    2016-07-01

    The PANDA experiment is one of the main devices at the upcoming Facility for Antiproton and Ion Research(FAIR), under construction in Darmstadt, Germany. This fixed target experiment will study the transition region between perturbative and non-perturbative QCD in the energy regime of the charmonium. The innermost sub-detector system of the target spectrometer of the PANDA experiment is the Micro Vertex Detector(MVD). Two types of silicon detectors will be used: pixel detectors and double-sided strip detectors. Two front-end chips are required: the Torino Pixel ASIC(ToPix) and the PANDA Strip ASIC(PASTA). Both are designed to transmit data at a rate of several hundred Megabits per second and are capable of handling the expected hit rate in hot spots of the detector. One key component in the development of new front-end electronics is a test system capable to handle these high rates. It should be flexible enough to test different kinds of front-end electronics and it should be easy to adapt to new prototypes. Therefore, an FPGA-based system is the ideal candidate. For this test system suitable firmware and a software framework are needed. Such a system is under development at the Forschungszentrum Juelich. The main component of the Juelich Digital Readout System(JDRS) is a Virtex 6 FPGA on a development board from Xilinx. In this talk, the mentioned read-out system are introduced, and lab tests with the front-end electronics of the MVD are presented.

  6. Towards hot electron mediated charge exchange in hyperthermal energy ion-surface interactions

    DEFF Research Database (Denmark)

    Ray, M. P.; Lake, R. E.; Thomsen, Lasse Bjørchmar

    2010-01-01

    shows that the primary energy loss mechanism is the atomic displacement of Au atoms in the thin film of the metal–oxide–semiconductor device. We propose that neutral particle detection of the scattered flux from a biased device could be a route to hot electron mediated charge exchange.......We have made Na + and He + ions incident on the surface of solid state tunnel junctions and measured the energy loss due to atomic displacement and electronic excitations. Each tunnel junction consists of an ultrathin film metal–oxide–semiconductor device which can be biased to create a band of hot...

  7. First wall and shield components manufacturing by hot isostatic pressing

    International Nuclear Information System (INIS)

    Lind, Anders; Tegman, R.

    1994-01-01

    At a meeting in Garching in June 1994 Hot Isostatic Pressing (HIP) was presented as a possible route to manufacture ITER first wall and shield components. The main advantages of the HIP concept include excellent and uniform mechanical properties of the produced materials and joints, high reliability and robustness of the HIP process, double containment of coolant, good flexibility concerning general design as well as size and location for inner cooling tubes, low cost and short delivery times, and a good near net shape capability for components in size up to 15 tons. To assess the applicability of HIP for the manufacturing of ITER first wall and shield components, it was agreed * to choose possible production parameters based in the present know-how, * to produce a compound mock-up in one shot from available solid steel/powder copper/steel tubes to demonstrate the joinability of the materials, * to examine the produced mock-up/materials by multi array ultrasonic testing, limited mechanical testing, metallography, scanning electron microscopy and energy dispersive spectroscopy, and * to compile data on Type 316L steels produced by HIP. Preliminary results and the mock-up were presented at a meeting in Garching in mid July 1994. This study clearly shows the excellent joinability of a copper alloy (Cu-0.5%Zr) and stainless steels (Type 304, 316 L) by HIP at temperatures close to the melting temperature of copper, with only limited influence on the microstructures, which makes it possible to HIP the first wall and shield structure in one step. Excellent mechanical properties of the compound are obtained with the copper alloy and not the joint being the weakest part. 7 refs, 21 figs, 1 tab

  8. Diffusion-Cooled Tantalum Hot-Electron Bolometer Mixers

    Science.gov (United States)

    Skalare, Anders; McGrath, William; Bumble, Bruce; LeDuc, Henry

    2004-01-01

    A batch of experimental diffusion-cooled hot-electron bolometers (HEBs), suitable for use as mixers having input frequencies in the terahertz range and output frequencies up to about a gigahertz, exploit the superconducting/normal-conducting transition in a thin strip of tantalum. The design and operation of these HEB mixers are based on mostly the same principles as those of a prior HEB mixer that exploited the superconducting/normal- conducting transition in a thin strip of niobium and that was described elsewhere.

  9. Technical report of electronics shop characteristics of high speed electronics component, (1)

    International Nuclear Information System (INIS)

    Watanabe, Shin-ichi; Shiino, Kazuo.

    1975-01-01

    We must develop electronics circuits for high speed signals. The electronics components of the circuits make use of the special components. This report treats a pulse response of the electronics components (i.e. coaxial cable, connector, resistor, capacitor, diode, transistor) for high speed electronics. The results of this report was already applied constructions of high speed electronics circuits and experimental equipments of the High Energy Physics Division. (auth.)

  10. Generation and Beaming of Early Hot Electrons onto the Capsule in Laser-Driven Ignition Hohlraums

    Science.gov (United States)

    Dewald, E. L.; Hartemann, F.; Michel, P.; Milovich, J.; Hohenberger, M.; Pak, A.; Landen, O. L.; Divol, L.; Robey, H. F.; Hurricane, O. A.; Döppner, T.; Albert, F.; Bachmann, B.; Meezan, N. B.; MacKinnon, A. J.; Callahan, D.; Edwards, M. J.

    2016-02-01

    In hohlraums for inertial confinement fusion (ICF) implosions on the National Ignition Facility, suprathermal hot electrons, generated by laser plasma instabilities early in the laser pulse ("picket") while blowing down the laser entrance hole (LEH) windows, can preheat the capsule fuel. Hard x-ray imaging of a Bi capsule surrogate and of the hohlraum emissions, in conjunction with the measurement of time-resolved bremsstrahlung spectra, allows us to uncover for the first time the directionality of these hot electrons and infer the capsule preheat. Data and Monte Carlo calculations indicate that for most experiments the hot electrons are emitted nearly isotropically from the LEH. However, we have found cases where a significant fraction of the generated electrons are emitted in a collimated beam directly towards the capsule poles, where their local energy deposition is up to 10 × higher than the average preheat value and acceptable levels for ICF implosions. The observed "beaming" is consistent with a recently unveiled multibeam stimulated Raman scattering model [P. Michel et al., Phys. Rev. Lett. 115, 055003 (2015)], where laser beams in a cone drive a common plasma wave on axis. Finally, we demonstrate that we can control the amount of generated hot electrons by changing the laser pulse shape and hohlraum plasma.

  11. Experimental studies on the production and suppression mechanism of the hot electrons produced by short wavelength laser

    International Nuclear Information System (INIS)

    Qi Lanying; Jiang Xiaohua; Zhao Xuewei; Li Sanwei; Zhang Wenhai; Li Chaoguang; Zheng Zhijian; Ding Yongkun

    1999-12-01

    The experiments on gold-disk and hohlraum and plastic hydrocarbon (CH) film targets irradiated by laser beams with wavelength 0.35 μm (Xingguang-II) and 0.53 μm (Shenguang-I) are performed. The characteristics of hot electrons are commonly deduced from spectrum of hard X-ray. Associated with the measurement of backward SRS and 3/2ω 0 , the production mechanism of hot electrons for different target type is analyzed in laser plasma with shorter wavelength. A effective way to suppress hot electrons has been found

  12. Origin of Power Laws for Reactions at Metal Surfaces Mediated by Hot Electrons

    DEFF Research Database (Denmark)

    Olsen, Thomas; Schiøtz, Jakob

    2009-01-01

    A wide range of experiments have established that certain chemical reactions at metal surfaces can be driven by multiple hot-electron-mediated excitations of adsorbates. A high transient density of hot electrons is obtained by means of femtosecond laser pulses and a characteristic feature of such...... density functional theory and the delta self-consistent field method. With a simplifying assumption, the power law becomes exact and we obtain a simple physical interpretation of the exponent n, which represents the number of adsorbate vibrational states participating in the reaction....

  13. Towards Prognostics for Electronics Components

    Data.gov (United States)

    National Aeronautics and Space Administration — Electronics components have an increasingly critical role in avionics systems and in the development of future aircraft systems. Prognostics of such components is...

  14. Fast ions and hot electrons in the laser--plasma interaction

    International Nuclear Information System (INIS)

    Gitomer, S.J.; Jones, R.D.; Begay, F.; Ehler, A.W.; Kephart, J.F.; Kristal, R.

    1986-01-01

    Data on the emission of energetic ions produced in laser--matter interactions have been analyzed for a wide variety of laser wavelengths, energies, and pulse lengths. Strong correlation has been found between the bulk energy per AMU for fast ions measured by charge cups and the x-ray-determined hot electron temperature. Five theoretical models have been used to explain this correlation. The models include (1) a steady-state spherically symmetric fluid model with classical electron heat conduction, (2) a steady-state spherically symmetric fluid model with flux limited electron heat conduction, (3) a simple analytic model of an isothermal rarefaction followed by a free expansion, (4) the lasneX hydrodynamics code [Comments Plasma Phys. Controlled Fusion 2, 85 (1975)], calculations employing a spherical expansion and simple initial conditions, and (5) the lasneX code with its full array of absorption, transport, and emission physics. The results obtained with these models are in good agreement with the experiments and indicate that the detailed shape of the correlation curve between mean fast ion energy and hot electron temperature is due to target surface impurities at the higher temperatures (higher laser intensities) and to the expansion of bulk target material at the lower temperatures (lower laser intensities)

  15. Effect of electron beam on the properties of electron-acoustic rogue waves

    Science.gov (United States)

    El-Shewy, E. K.; Elwakil, S. A.; El-Hanbaly, A. M.; Kassem, A. I.

    2015-04-01

    The properties of nonlinear electron-acoustic rogue waves have been investigated in an unmagnetized collisionless four-component plasma system consisting of a cold electron fluid, Maxwellian hot electrons, an electron beam and stationary ions. It is found that the basic set of fluid equations is reduced to a nonlinear Schrodinger equation. The dependence of rogue wave profiles and the associated electric field on the carrier wave number, normalized density of hot electron and electron beam, relative cold electron temperature and relative beam temperature are discussed. The results of the present investigation may be applicable in auroral zone plasma.

  16. Transport effects with hot electrons in laser fusion. Final report, October 1, 1981-February 28, 1983

    International Nuclear Information System (INIS)

    Shkarofsky, I.P.

    1983-02-01

    Two explanations are offered which can account for heat inhibition found in laser-fusion experiments. The first explanation requires an anisotorpic electron velocity distribution with a higher temperature parallel to the surface than into the surface. This provides axial heat inhibition. Lateral heat inhibition is associated with azimuthal magnetic fields. The second explanation requires the presence of both hot suprathermal and thermal electrons. The hot electrons can cause the flux limiter to decrease substantially below the free-streaming limit in an intermediate range of collisionality. Conditions for this situation occur in the coronal region. We compare a Maxwellian distribution to an exp(-v 5 /v 5 /sub c/) variation for the cold electrons and find that the flux limiter decreases more for the latter case. The effects of collisions between cold and hot electrons is also looked into. The Cartesian tensor approach is used in the above investigations with various forms for the zeroth order electron velocity distribution function

  17. Power electronics handbook components, circuits and applications

    CERN Document Server

    Mazda, F F

    1993-01-01

    Power Electronics Handbook: Components, Circuits, and Applications is a collection of materials about power components, circuit design, and applications. Presented in a practical form, theoretical information is given as formulae. The book is divided into three parts. Part 1 deals with the usual components found in power electronics such as semiconductor devices and power semiconductor control components, their electronic compatibility, and protection. Part 2 tackles parts and principles related to circuits such as switches; link frequency chargers; converters; and AC line control, and Part 3

  18. Going ballistic: Graphene hot electron transistors

    Science.gov (United States)

    Vaziri, S.; Smith, A. D.; Östling, M.; Lupina, G.; Dabrowski, J.; Lippert, G.; Mehr, W.; Driussi, F.; Venica, S.; Di Lecce, V.; Gnudi, A.; König, M.; Ruhl, G.; Belete, M.; Lemme, M. C.

    2015-12-01

    This paper reviews the experimental and theoretical state of the art in ballistic hot electron transistors that utilize two-dimensional base contacts made from graphene, i.e. graphene base transistors (GBTs). Early performance predictions that indicated potential for THz operation still hold true today, even with improved models that take non-idealities into account. Experimental results clearly demonstrate the basic functionality, with on/off current switching over several orders of magnitude, but further developments are required to exploit the full potential of the GBT device family. In particular, interfaces between graphene and semiconductors or dielectrics are far from perfect and thus limit experimental device integrity, reliability and performance.

  19. Importance of field-reversing ion ring formation in hot electron plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ikuta, K.

    1975-11-01

    Formation of the field reversing ion ring in the mirror confined hot electron plasma may offer a device to confine the fusion plasma even under the restriction of the present technology. (Author) (GRA)

  20. Design and rescue scenario of common repair equipment for in-vessel components in ITER hot cell

    International Nuclear Information System (INIS)

    Kakudate, Satoshi; Takeda, Nobukazu; Nakahira, Masataka; Shibanuma, Kiyoshi

    2006-06-01

    Transportation of the in-vessel components to be repaired in the ITER hot cell is carried by two kinds of transporters, i.e., overhead cranes and floor vehicles. The access area for repair operations in the hot cell is duplicated by these transporters. Clear sharing of the respective roles of these transporters with the minimum duplication is therefore useful for rationalization. The overhead cranes, which are independently installed in the respective cells in the hot sell, cannot pass through the components to be repaired between cells, i.e., receiving cell and refurbishment cell as an example. If the floor vehicle with simple mechanisms can cover the inaccessible area for the overhead cranes, a global transporter system in the hot cell will be simplified and the reliability will be increased. Based on this strategy, the overhead crane and floor vehicle concepts are newly proposed. The overhead crane has an adapter for change of the end-effectors, which can be easily changed, to grasp many kinds of components to be repaired. The floor vehicle, which is equipped with wheel mechanisms for transportation, is just to pass through the components between cells with only straight (linear) motion on the floor. The simple wheel mechanism can solve the spread of the dust, which is the critical issue of the original air bearing mechanism for traveling in the 2001 FDR design. Rescue scenarios and procedures in the hot cell are also studied in this report. The proposed rescue crane has major two functions for rescue operations of the hot cell facility, i.e., one for the overhead crane and the other for refurbishment equipment such as workstation for divertor repair. The rescue of the faulty overhead crane is carried out using the rescue tool installed on the rescue crane or directly traveled by pushing/pulling by the rescue crane after docking on the faulty overhead crane. For the rescue of the workstation, the rescue crane consists of a telescopic manipulator (maximum length

  1. Investigation of hot cracking in deep penetration electron beam welds

    Energy Technology Data Exchange (ETDEWEB)

    Thorvaldson, W.G.

    1978-06-10

    A defect in a deep penetration electron beam weld of 304L stainless steel to 21-6-9 stainless steel has been identified as a centerline hot crack. The study discussed in this report was made to define and to eliminate the cause of cracking.

  2. Limitation and suppression of hot electron fluctuations in submicron semiconductor structures

    International Nuclear Information System (INIS)

    Kochelap, V.A.; Zahleniuk, N.A.; Sokolov, V.N.

    1992-09-01

    We present theoretical investigations of fluctuations of hot electrons in submicron active regions, where the dimensions 2 d of the region is comparable to the electron energy relaxation length L ε . The new physical phenomenon is reported; the fluctuations depend on the sample thickness, with 2d ε a suppression of fluctuations arises in the range of fluctuation frequencies ω much less than T -1 ε , T ε is the electron energy relaxation time. (author). 12 refs, 7 figs

  3. Terahertz hot electron bolometer waveguide mixers for GREAT

    OpenAIRE

    Pütz, P.; Honingh, C. E.; Jacobs, K.; Justen, M.; Schultz, M.; Stutzki, J.

    2012-01-01

    Supplementing the publications based on the first-light observations with the German Receiver for Astronomy at Terahertz frequencies (GREAT) on SOFIA, we present background information on the underlying heterodyne detector technology. We describe the superconducting hot electron bolometer (HEB) detectors that are used as frequency mixers in the L1 (1400 GHz), L2 (1900 GHz), and M (2500 GHz) channels of GREAT. Measured performance of the detectors is presented and background information on the...

  4. Hot Electron Photoemission from Plasmonic Nanostructures: The Role of Surface Photoemission and Transition Absorption

    DEFF Research Database (Denmark)

    Babicheva, Viktoriia; Zhukovsky, Sergei; Ikhsanov, Renat Sh

    2015-01-01

    We study mechanisms of photoemission of hot electrons from plasmonic nanoparticles. We analyze the contribution of "transition absorption", i.e., loss of energy of electrons passing through the boundary between different materials, to the surface mechanism of photoemission. We calculate photoemis......We study mechanisms of photoemission of hot electrons from plasmonic nanoparticles. We analyze the contribution of "transition absorption", i.e., loss of energy of electrons passing through the boundary between different materials, to the surface mechanism of photoemission. We calculate...... photoemission rate and transition absorption for nanoparticles surrounded by various media with a broad range of permittivities and show that photoemission rate and transition absorption follow the same dependence on the permittivity. Thus, we conclude that transition absorption is responsible...

  5. Some recent results from European sounding rocket and satellite observations of the hot magnetospheric plasma

    International Nuclear Information System (INIS)

    Hultqvist, B.

    1979-03-01

    A brief summary of some recent results from European studies of the hot magnetospheric plasma is presented. The material is organized in four main sections: 1) Observations of keV auroral electrons. 2) Observation of the hot ion component of the magnetospheric plasma. 3) Sudden changes of the distribution of the hot plasma in the dayside magnetosphere. 4) Banded electron cyclotron harmonic instability in the magnetosphere - a first comparison of theory and experiment. (E.R.)

  6. Non-Fourier Heat Transfer with Phonons and Electrons in a Circular Thin Layer Surrounding a Hot Nanodevice

    Directory of Open Access Journals (Sweden)

    Vito Antonio Cimmelli

    2015-07-01

    Full Text Available A nonlocal model for heat transfer with phonons and electrons is applied to infer the steady-state radial temperature profile in a circular layer surrounding an inner hot component. Such a profile, following by the numerical solution of the heat equation, predicts that the temperature behaves in an anomalous way, since for radial distances from the heat source smaller than the mean-free path of phonons and electrons, it increases for increasing distances. The compatibility of this temperature behavior with the second law of thermodynamics is investigated by calculating numerically the local entropy production as a function of the radial distance. It turns out that such a production is positive and strictly decreasing with the radial distance.

  7. Electronic oscillations in a hot plasma due the non-Maxwellian velocity distributions

    International Nuclear Information System (INIS)

    Dias, L.A.V.; Nakamura, Y.

    1977-01-01

    In a completely ionized hot plasma, with a non-Maxwellian electron velocity distribution, it is shown that, depending on the electron temperature, oscillations may occur at the elctron plasma and gyro frequencies. For three different electron velocity distributions, it is shown the oscillations dependency on the temperature. This situation occurs in the ionospheric plasma when artificially heated by HF radio waves. If the distribution is Maxwellian, the oscillation only occur near the electron plasma frequency [pt

  8. Fast Advection of Magnetic Fields by Hot Electrons

    International Nuclear Information System (INIS)

    Willingale, L.; Thomas, A. G. R.; Krushelnick, K.; Nilson, P. M.; Kaluza, M. C.; Dangor, A. E.; Evans, R. G.; Fernandes, P.; Haines, M. G.; Kamperidis, C.; Kingham, R. J.; Ridgers, C. P.; Sherlock, M.; Wei, M. S.; Najmudin, Z.; Bandyopadhyay, S.; Notley, M.; Minardi, S.; Tatarakis, M.; Rozmus, W.

    2010-01-01

    Experiments where a laser-generated proton beam is used to probe the megagauss strength self-generated magnetic fields from a nanosecond laser interaction with an aluminum target are presented. At intensities of 10 15 W cm -2 and under conditions of significant fast electron production and strong heat fluxes, the electron mean-free-path is long compared with the temperature gradient scale length and hence nonlocal transport is important for the dynamics of the magnetic field in the plasma. The hot electron flux transports self-generated magnetic fields away from the focal region through the Nernst effect [A. Nishiguchi et al., Phys. Rev. Lett. 53, 262 (1984)] at significantly higher velocities than the fluid velocity. Two-dimensional implicit Vlasov-Fokker-Planck modeling shows that the Nernst effect allows advection and self-generation transports magnetic fields at significantly faster than the ion fluid velocity, v N /c s ≅10.

  9. Modelling hot electron generation in short pulse target heating experiments

    Directory of Open Access Journals (Sweden)

    Sircombe N.J.

    2013-11-01

    Full Text Available Target heating experiments planned for the Orion laser facility, and electron beam driven fast ignition schemes, rely on the interaction of a short pulse high intensity laser with dense material to generate a flux of energetic electrons. It is essential that the characteristics of this electron source are well known in order to inform transport models in radiation hydrodynamics codes and allow effective evaluation of experimental results and forward modelling of future campaigns. We present results obtained with the particle in cell (PIC code EPOCH for realistic target and laser parameters, including first and second harmonic light. The hot electron distributions are characterised and their implications for onward transport and target heating are considered with the aid of the Monte-Carlo transport code THOR.

  10. Towards Prognostics for Electronics Components

    Science.gov (United States)

    Saha, Bhaskar; Celaya, Jose R.; Wysocki, Philip F.; Goebel, Kai F.

    2013-01-01

    Electronics components have an increasingly critical role in avionics systems and in the development of future aircraft systems. Prognostics of such components is becoming a very important research field as a result of the need to provide aircraft systems with system level health management information. This paper focuses on a prognostics application for electronics components within avionics systems, and in particular its application to an Isolated Gate Bipolar Transistor (IGBT). This application utilizes the remaining useful life prediction, accomplished by employing the particle filter framework, leveraging data from accelerated aging tests on IGBTs. These tests induced thermal-electrical overstresses by applying thermal cycling to the IGBT devices. In-situ state monitoring, including measurements of steady-state voltages and currents, electrical transients, and thermal transients are recorded and used as potential precursors of failure.

  11. Prediction of hot electron production by ultraintense KrF laser-plasma interactions on solid-density targets

    International Nuclear Information System (INIS)

    Kato, Susumu; Takahashi, Eiichi; Miura, Eisuke; Owadano, Yoshiro; Nakamura, Tatsufumi; Kato, Tomokazu

    2002-01-01

    The scaling of hot electron temperature and the spectrum of electron energy by intense laser plasma interactions are reexamined from a viewpoint of the difference in laser wavelength. Laser plasma interaction such as parametric instabilities is usually determined by the Iλ2 scaling, where I and λ is the laser intensity and wavelength, respectively. However, the hot electron temperature is proportional to (ncr/ne0)1/2 [(1 + a 0 2 ) 1/2 - 1] rather than [(1 + a 0 2 ) 1/2 - 1] at the interaction with overdense plasmas, where ne0 is a electron density of overdense plasmas and a0 is a normalized laser intensity

  12. Electric field dependence of the temperature and drift velocity of hot electrons in n-Si

    International Nuclear Information System (INIS)

    Vass, E.

    2001-01-01

    Full text: The average energy- and momentum loss rates of hot electrons interacting simultaneously with acoustic phonons, ionized and neutral impurities in n-Si are calculated quantum theoretically by means of a drifted hot Fermi-Dirac distribution. The drift velocity vd and electron temperature Te occurring in this distribution are determined self-consistently from the force- and power balance equation with respect to the charge neutrality condition. The functions Te(E) and vd(E) calculated in this way are compared with the corresponding relations obtained with help of the simple electron temperature model in order to determine the range of application of this model often used in previous treatises. (author)

  13. Electron beam-plasma interaction and electron-acoustic solitary waves in a plasma with suprathermal electrons

    Science.gov (United States)

    Danehkar, A.

    2018-06-01

    Suprathermal electrons and inertial drifting electrons, so called electron beam, are crucial to the nonlinear dynamics of electrostatic solitary waves observed in several astrophysical plasmas. In this paper, the propagation of electron-acoustic solitary waves (EAWs) is investigated in a collisionless, unmagnetized plasma consisting of cool inertial background electrons, hot suprathermal electrons (modeled by a κ-type distribution), and stationary ions. The plasma is penetrated by a cool electron beam component. A linear dispersion relation is derived to describe small-amplitude wave structures that shows a weak dependence of the phase speed on the electron beam velocity and density. A (Sagdeev-type) pseudopotential approach is employed to obtain the existence domain of large-amplitude solitary waves, and investigate how their nonlinear structures depend on the kinematic and physical properties of the electron beam and the suprathermality (described by κ) of the hot electrons. The results indicate that the electron beam can largely alter the EAWs, but can only produce negative polarity solitary waves in this model. While the electron beam co-propagates with the solitary waves, the soliton existence domain (Mach number range) becomes narrower (nearly down to nil) with increasing the beam speed and the beam-to-hot electron temperature ratio, and decreasing the beam-to-cool electron density ratio in high suprathermality (low κ). It is found that the electric potential amplitude largely declines with increasing the beam speed and the beam-to-cool electron density ratio for co-propagating solitary waves, but is slightly decreased by raising the beam-to-hot electron temperature ratio.

  14. Origin of depleted components in basalt related to the Hawaiian hot spot: Evidence from isotopic and incompatible element ratios

    Science.gov (United States)

    Frey, F. A.; Huang, S.; Blichert-Toft, J.; Regelous, M.; Boyet, M.

    2005-02-01

    The radiogenic isotopic ratios of Sr, Nd, Hf, and Pb in basaltic lavas associated with major hot spots, such as Hawaii, document the geochemical heterogeneity of their mantle source. What processes created such heterogeneity? For Hawaiian lavas there has been extensive discussion of geochemically enriched source components, but relatively little attention has been given to the origin of depleted source components, that is, components with the lowest 87Sr/86Sr and highest 143Nd/144Nd and 176Hf/177Hf. The surprisingly important role of a depleted component in the source of the incompatible element-enriched, rejuvenated-stage Hawaiian lavas is well known. A depleted component also contributed significantly to the ˜76-81 Ma lavas erupted at Detroit Seamount in the Emperor Seamount Chain. In both cases, major involvement of MORB-related depleted asthenosphere or lithosphere has been proposed. Detroit Seamount and rejuvenated-stage lavas, however, have important isotopic differences from most Pacific MORB. Specifically, they define trends to relatively unradiogenic Pb isotope ratios, and most Emperor Seamount lavas define a steep trend of 176Hf/177Hf versus 143Nd/144Nd. In addition, lavas from Detroit Seamount and recent rejuvenated-stage lavas have relatively high Ba/Th, a characteristic of lavas associated with the Hawaiian hot spot. It is possible that a depleted component, intrinsic to the hot spot, has contributed to these young and old lavas related to the Hawaiian hot spot. The persistence of such a component over 80 Myr is consistent with a long-lived source, i.e., a plume.

  15. Spin-dependent hot electron transport and nano-scale magnetic imaging of metal/Si structures

    International Nuclear Information System (INIS)

    Kaidatzis, A.

    2008-10-01

    In this work, we experimentally study spin-dependent hot electron transport through metallic multilayers (ML), containing single magnetic layers or 'spin-valve' (SV) tri layers. For this purpose, we have set up a ballistic electron emission microscope (BEEM), a three terminal extension of scanning tunnelling microscopy on metal/semiconductor structures. The implementation of the BEEM requirements into the sample fabrication is described in detail. Using BEEM, the hot electron transmission through the ML's was systematically measured in the energy range 1-2 eV above the Fermi level. By varying the magnetic layer thickness, the spin-dependent hot electron attenuation lengths were deduced. For the materials studied (Co and NiFe), they were compared to calculations and other determinations in the literature. For sub-monolayer thickness, a non uniform morphology was observed, with large transmission variations over sub-nano-metric distances. This effect is not yet fully understood. In the imaging mode, the magnetic configurations of SV's were studied under field, focusing on 360 degrees domain walls in Co layers. The effects of the applied field intensity and direction on the DW structure were studied. The results were compared quantitatively to micro-magnetic calculations, with an excellent agreement. From this, it can be shown that the BEEM magnetic resolution is better than 50 nm. (author)

  16. Multilayer electronic component systems and methods of manufacture

    Science.gov (United States)

    Thompson, Dane (Inventor); Wang, Guoan (Inventor); Kingsley, Nickolas D. (Inventor); Papapolymerou, Ioannis (Inventor); Tentzeris, Emmanouil M. (Inventor); Bairavasubramanian, Ramanan (Inventor); DeJean, Gerald (Inventor); Li, RongLin (Inventor)

    2010-01-01

    Multilayer electronic component systems and methods of manufacture are provided. In this regard, an exemplary system comprises a first layer of liquid crystal polymer (LCP), first electronic components supported by the first layer, and a second layer of LCP. The first layer is attached to the second layer by thermal bonds. Additionally, at least a portion of the first electronic components are located between the first layer and the second layer.

  17. Fokker-Planck simulation of runaway electron generation in disruptions with the hot-tail effect

    Energy Technology Data Exchange (ETDEWEB)

    Nuga, H., E-mail: nuga@p-grp.nucleng.kyoto-u.ac.jp; Fukuyama, A. [Department of Engineering, Kyoto University, Kyoto 615-8540 (Japan); Yagi, M. [National Institutes for Quantum and Radiological Science and Technology, Aomori 039-3212 (Japan)

    2016-06-15

    To study runaway electron generation in disruptions, we have extended the three-dimensional (two-dimensional in momentum space; one-dimensional in the radial direction) Fokker-Planck code, which describes the evolution of the relativistic momentum distribution function of electrons and the induced toroidal electric field in a self-consistent manner. A particular focus is placed on the hot-tail effect in two-dimensional momentum space. The effect appears if the drop of the background plasma temperature is sufficiently rapid compared with the electron-electron slowing down time for a few times of the pre-quench thermal velocity. It contributes to not only the enhancement of the primary runaway electron generation but also the broadening of the runaway electron distribution in the pitch angle direction. If the thermal energy loss during the major disruption is assumed to be isotropic, there are hot-tail electrons that have sufficiently large perpendicular momentum, and the runaway electron distribution becomes broader in the pitch angle direction. In addition, the pitch angle scattering also yields the broadening. Since the electric field is reduced due to the burst of runaway electron generation, the time required for accelerating electrons to the runaway region becomes longer. The longer acceleration period makes the pitch-angle scattering more effective.

  18. Korteweg-deVries-Burgers (KdVB) equation in a five component cometary plasma with kappa described electrons and ions

    Science.gov (United States)

    Michael, Manesh; Willington, Neethu T.; Jayakumar, Neethu; Sebastian, Sijo; Sreekala, G.; Venugopal, Chandu

    2016-12-01

    We investigate the existence of ion-acoustic shock waves in a five component cometary plasma consisting of positively and negatively charged oxygen ions, kappa described hydrogen ions, hot solar electrons, and slightly colder cometary electrons. The KdVB equation has been derived for the system, and its solution plotted for different kappa values, oxygen ion densities, as well as the temperature ratios for the ions. It is found that the amplitude of the shock wave decreases with increasing kappa values. The strength of the shock profile decreases with increasing temperatures of the positively charged oxygen ions and densities of negatively charged oxygen ions.

  19. Contribution to the determination of priority constructive influences on the hot crack initiation of welded components

    International Nuclear Information System (INIS)

    Gollnow, Christian

    2015-01-01

    The previous research results do not allow a general hot crack characterisation although a variety of experimental and numerical knowledge is available. The reason for this is mainly the large number of influencing factors that complicate a complete description of the hot cracking phenomenon and especially solidification cracking. The hot crack formation and thus the solidification crack initiation can be described by the interaction of process, metallurgy and design. However, the literature examination shows that in the solidifaction crack characterisation the influence of the design aspect is often underestimated. The pre-stresses of the structural components is up to now not considered as an essential cause for the formation of solidification cracks. The evaluation of the influence of the various parameters is presented partly inconsistent. In addition, the targeted presentation of the design influence with respect to the solidification cracks in the weld is because the limited transferability of the various component-specific stresses on a laboratory scale and thus to the respective hot cracking tests restricted. Hence, the difficulty to transfer the results between laboratory specimen and component as well as the general hot crack characterisation is given. In this work the different types of stresses from the component welding in the laboratory and to quantify experimentally the solidification crack critical values, displacements and displacement rates were detected. In this regard external loaded hot cracking tests were carried out by using the advantages of contactless measurement techniques close to the weld and to analyse the welding process with respect to various local and global design-specific factors influencing the formation of solidification cracks in high alloyed steel. These investigations were performed on austenitic (1.4828) and ferritic (1.4509) materials with different mechanical and technological properties. To reflect the praxis relevant

  20. Current gain above 10 in sub-10 nm base III-Nitride tunneling hot electron transistors with GaN/AlN emitter

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhichao, E-mail: zcyang.phys@gmail.com; Zhang, Yuewei; Krishnamoorthy, Sriram; Nath, Digbijoy N. [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Khurgin, Jacob B. [Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Rajan, Siddharth [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)

    2016-05-09

    We report on a tunneling hot electron transistor amplifier with common-emitter current gain greater than 10 at a collector current density in excess of 40 kA/cm{sup 2}. The use of a wide-bandgap GaN/AlN (111 nm/2.5 nm) emitter was found to greatly improve injection efficiency of the emitter and reduce cold electron leakage. With an ultra-thin (8 nm) base, 93% of the injected hot electrons were collected, enabling a common-emitter current gain up to 14.5. This work improves understanding of the quasi-ballistic hot electron transport and may impact the development of high speed devices based on unipolar hot electron transport.

  1. Electrogenerated chemiluminescence induced by sequential hot electron and hole injection into aqueous electrolyte solution

    Energy Technology Data Exchange (ETDEWEB)

    Salminen, Kalle; Kuosmanen, Päivi; Pusa, Matti [Aalto University, Department of Chemistry, Laboratory of Analytical Chemistry, P.O. Box 16100, FI-00076 Aalto (Finland); Kulmala, Oskari [University of Helsinki, Department of Physics, P.O. Box 64, FI-00014 (Finland); Håkansson, Markus [Aalto University, Department of Chemistry, Laboratory of Analytical Chemistry, P.O. Box 16100, FI-00076 Aalto (Finland); Kulmala, Sakari, E-mail: sakari.kulmala@aalto.fi [Aalto University, Department of Chemistry, Laboratory of Analytical Chemistry, P.O. Box 16100, FI-00076 Aalto (Finland)

    2016-03-17

    Hole injection into aqueous electrolyte solution is proposed to occur when oxide-coated aluminum electrode is anodically pulse-polarized by a voltage pulse train containing sufficiently high-voltage anodic pulses. The effects of anodic pulses are studied by using an aromatic Tb(III) chelate as a probe known to produce intensive hot electron-induced electrochemiluminescence (HECL) with plain cathodic pulses and preoxidized electrodes. The presently studied system allows injection of hot electrons and holes successively into aqueous electrolyte solutions and can be utilized in detecting electrochemiluminescent labels in fully aqueous solutions, and actually, the system is suggested to be quite close to a pulse radiolysis system providing hydrated electrons and hydroxyl radicals as the primary radicals in aqueous solution without the problems and hazards of ionizing radiation. The analytical power of the present excitation waveforms are that they allow detection of electrochemiluminescent labels at very low detection limits in bioaffinity assays such as in immunoassays or DNA probe assays. The two important properties of the present waveforms are: (i) they provide in situ oxidation of the electrode surface resulting in the desired oxide film thickness and (ii) they can provide one-electron oxidants for the system by hole injection either via F- and F{sup +}-center band of the oxide or by direct hole injection to valence band of water at highly anodic pulse amplitudes. - Highlights: • Hot electrons injected into aqueous electrolyte solution. • Generation of hydrated electrons. • Hole injection into aqueous electrolyte solution. • Generation of hydroxyl radicals.

  2. Antenna-coupled 30 THz hot electron bolometer mixers

    OpenAIRE

    Shcherbatenko, M.; Lobanov, Y.; Benderov, O.; Shurakov, A.; Ignatov, A.; Titova, N.; Finkel, M.; Maslennikov, S.; Kaurova, N.; Voronov, B.M.; Rodin, A.; Klapwijk, T.M.; Gol'tsman, G.N.

    2015-01-01

    We report on design and characterization of a superconducting Hot Electron Bolometer Mixer integrated with a logarithmic spiral antenna for mid-IR range observations. The antenna parameters have been adjusted to achieve the ultimate performance at 10 ?m (30 THz) range where O3, NH3, CO2, CH4, N2O, …. lines in the Earth’s atmosphere, in planetary atmospheres and in the interstellar space can be observed. The HEB mixer is made of a thin NbN film deposited onto a GaAs substrate. To couple the ra...

  3. Hot LO-phonon limited electron transport in ZnO/MgZnO channels

    Science.gov (United States)

    Šermukšnis, E.; Liberis, J.; Matulionis, A.; Avrutin, V.; Toporkov, M.; Özgür, Ü.; Morkoç, H.

    2018-05-01

    High-field electron transport in two-dimensional channels at ZnO/MgZnO heterointerfaces has been investigated experimentally. Pulsed current-voltage (I-V) and microwave noise measurements used voltage pulse widths down to 30 ns and electric fields up to 100 kV/cm. The samples investigated featured electron densities in the range of 4.2-6.5 × 1012 cm-2, and room temperature mobilities of 142-185 cm2/V s. The pulsed nature of the applied field ensured negligible, if any, change in the electron density, thereby allowing velocity extraction from current with confidence. The highest extracted electron drift velocity of ˜0.5 × 107 cm/s is somewhat smaller than that estimated for bulk ZnO; this difference is explained in the framework of longitudinal optical phonon accumulation (hot-phonon effect). The microwave noise data allowed us to rule out the effect of excess acoustic phonon temperature caused by Joule heating. Real-space transfer of hot electrons into the wider bandgap MgZnO layer was observed to be a limiting factor in samples with a high Mg content (48%), due to phase segregation and the associated local lowering of the potential barrier.

  4. Origins and Scaling of Hot-Electron Preheat in Ignition-Scale Direct-Drive Inertial Confinement Fusion Experiments

    Science.gov (United States)

    Rosenberg, M. J.; Solodov, A. A.; Myatt, J. F.; Seka, W.; Michel, P.; Hohenberger, M.; Short, R. W.; Epstein, R.; Regan, S. P.; Campbell, E. M.; Chapman, T.; Goyon, C.; Ralph, J. E.; Barrios, M. A.; Moody, J. D.; Bates, J. W.

    2018-01-01

    Planar laser-plasma interaction (LPI) experiments at the National Ignition Facility (NIF) have allowed access for the first time to regimes of electron density scale length (˜500 to 700 μ m ), electron temperature (˜3 to 5 keV), and laser intensity (6 to 16 ×1014 W /cm2 ) that are relevant to direct-drive inertial confinement fusion ignition. Unlike in shorter-scale-length plasmas on OMEGA, scattered-light data on the NIF show that the near-quarter-critical LPI physics is dominated by stimulated Raman scattering (SRS) rather than by two-plasmon decay (TPD). This difference in regime is explained based on absolute SRS and TPD threshold considerations. SRS sidescatter tangential to density contours and other SRS mechanisms are observed. The fraction of laser energy converted to hot electrons is ˜0.7 % to 2.9%, consistent with observed levels of SRS. The intensity threshold for hot-electron production is assessed, and the use of a Si ablator slightly increases this threshold from ˜4×10 14 to ˜6 ×1014 W /cm2 . These results have significant implications for mitigation of LPI hot-electron preheat in direct-drive ignition designs.

  5. Gap-plasmon based broadband absorbers for enhanced hot-electron and photocurrent generation

    DEFF Research Database (Denmark)

    Lu, Yuhua; Dong, Wen; Chen, Zhuo

    2016-01-01

    Plasmonic hot-electron generation has recently come into focus as a new scheme for solar energy conversion. So far, however, due to the relatively narrow bandwidth of the surface plasmon resonances and the insufficient resonant light absorption, most of plasmonic photocatalysts show narrow......-band spectral responsivities and small solar energy conversion efficiencies. Here we experimentally demonstrate that a three-layered nanostructure, consisting of a monolayer gold-nanoparticles and a gold film separated by a TiO2 gap layer (Au-NPs/TiO2/Au-film), is capable of near-completely absorbing light...... within the whole visible region. We show that the Au-NPs/TiO2/Au-film device can take advantage of such strong and broadband light absorption to enhance the generation of hot electrons and thus the photocurrent under visible irradiation. As compared to conventional plasmonic photocatalysts such as Au...

  6. Localized structures of electromagnetic waves in hot electron-positron plasma

    International Nuclear Information System (INIS)

    Kartal, S.; Tsintsadze, L.N.; Berezhiani, V.I.

    1995-08-01

    The dynamics of relatively strong electromagnetic (EM) wave propagation in hot electron-positron plasma is investigated. The possibility of finding localized stationary structures of EM waves is explored. It it shown that under certain conditions the EM wave forms a stable localized soliton-like structures where plasma is completely expelled from the region of EM field location. (author). 9 refs, 2 figs

  7. Radiation dose effects, hardening of electronic components

    International Nuclear Information System (INIS)

    Dupont-Nivet, E.

    1991-01-01

    This course reviews the mechanism of interaction between ionizing radiation and a silicon oxide type dielectric, in particular the effect of electron-hole pairs creation in the material. Then effects of cumulated dose on electronic components and especially in MOS technology are examined. Finally methods hardening of these components are exposed. 93 refs

  8. Automated cleaning of electronic components

    International Nuclear Information System (INIS)

    Drotning, W.; Meirans, L.; Wapman, W.; Hwang, Y.; Koenig, L.; Petterson, B.

    1994-01-01

    Environmental and operator safety concerns are leading to the elimination of trichloroethylene and chlorofluorocarbon solvents in cleaning processes that remove rosin flux, organic and inorganic contamination, and particulates from electronic components. Present processes depend heavily on these solvents for manual spray cleaning of small components and subassemblies. Use of alternative solvent systems can lead to longer processing times and reduced quality. Automated spray cleaning can improve the quality of the cleaning process, thus enabling the productive use of environmentally conscious materials, while minimizing personnel exposure to hazardous materials. We describe the development of a prototype robotic system for cleaning electronic components in a spray cleaning workcell. An important feature of the prototype system is the capability to generate the robot paths and motions automatically from the CAD models of the part to be cleaned, and to embed cleaning process knowledge into the automatically programmed operations

  9. Model for ion confinement in a hot-electron tandem mirror anchor

    International Nuclear Information System (INIS)

    Baldwin, D.E.

    1980-01-01

    Anisotropic, hot electrons trapped in local minimum-B wells have been proposed as MHD-stabilizing anchors to an otherwise axisymmetric tandem configuration. This work describes a model for plasma confinement between the anchors and the remainder of the system and calcuates the power loss implied by maintenance of this plasma

  10. Submolecular Gates Self-Assemble for Hot-Electron Transfer in Proteins.

    Science.gov (United States)

    Filip-Granit, Neta; Goldberg, Eran; Samish, Ilan; Ashur, Idan; van der Boom, Milko E; Cohen, Hagai; Scherz, Avigdor

    2017-07-27

    Redox reactions play key roles in fundamental biological processes. The related spatial organization of donors and acceptors is assumed to undergo evolutionary optimization facilitating charge mobilization within the relevant biological context. Experimental information from submolecular functional sites is needed to understand the organization strategies and driving forces involved in the self-development of structure-function relationships. Here we exploit chemically resolved electrical measurements (CREM) to probe the atom-specific electrostatic potentials (ESPs) in artificial arrays of bacteriochlorophyll (BChl) derivatives that provide model systems for photoexcited (hot) electron donation and withdrawal. On the basis of computations we show that native BChl's in the photosynthetic reaction center (RC) self-assemble at their ground-state as aligned gates for functional charge transfer. The combined computational and experimental results further reveal how site-specific polarizability perpendicular to the molecular plane enhances the hot-electron transport. Maximal transport efficiency is predicted for a specific, ∼5 Å, distance above the center of the metalized BChl, which is in remarkably close agreement with the distance and mutual orientation of corresponding native cofactors. These findings provide new metrics and guidelines for analysis of biological redox centers and for designing charge mobilizing machines such as artificial photosynthesis.

  11. Efficient, Broadband and Wide-Angle Hot-Electron Transduction using Metal-Semiconductor Hyperbolic Metamaterials

    KAUST Repository

    Sakhdari, Maryam; Hajizadegan, Mehdi; Farhat, Mohamed; Chen, Pai-Yen

    2016-01-01

    Hot-electron devices are emerging as promising candidates for the transduction of optical radiation into electrical current, as they enable photodetection and solar/infrared energy harvesting at sub-bandgap wavelengths. Nevertheless, poor

  12. Micron-scale mapping of megagauss magnetic fields using optical polarimetry to probe hot electron transport in petawatt-class laser-solid interactions.

    Science.gov (United States)

    Chatterjee, Gourab; Singh, Prashant Kumar; Robinson, A P L; Blackman, D; Booth, N; Culfa, O; Dance, R J; Gizzi, L A; Gray, R J; Green, J S; Koester, P; Kumar, G Ravindra; Labate, L; Lad, Amit D; Lancaster, K L; Pasley, J; Woolsey, N C; Rajeev, P P

    2017-08-21

    The transport of hot, relativistic electrons produced by the interaction of an intense petawatt laser pulse with a solid has garnered interest due to its potential application in the development of innovative x-ray sources and ion-acceleration schemes. We report on spatially and temporally resolved measurements of megagauss magnetic fields at the rear of a 50-μm thick plastic target, irradiated by a multi-picosecond petawatt laser pulse at an incident intensity of ~10 20 W/cm 2 . The pump-probe polarimetric measurements with micron-scale spatial resolution reveal the dynamics of the magnetic fields generated by the hot electron distribution at the target rear. An annular magnetic field profile was observed ~5 ps after the interaction, indicating a relatively smooth hot electron distribution at the rear-side of the plastic target. This is contrary to previous time-integrated measurements, which infer that such targets will produce highly structured hot electron transport. We measured large-scale filamentation of the hot electron distribution at the target rear only at later time-scales of ~10 ps, resulting in a commensurate large-scale filamentation of the magnetic field profile. Three-dimensional hybrid simulations corroborate our experimental observations and demonstrate a beam-like hot electron transport at initial time-scales that may be attributed to the local resistivity profile at the target rear.

  13. Electronic components and technology

    CERN Document Server

    Sangwine, Stephen

    2007-01-01

    Most introductory textbooks in electronics focus on the theory while leaving the practical aspects to be covered in laboratory courses. However, the sooner such matters are introduced, the better able students will be to include such important concerns as parasitic effects and reliability at the very earliest stages of design. This philosophy has kept Electronic Components and Technology thriving for two decades, and this completely updated third edition continues the approach with a more international outlook.Not only does this textbook introduce the properties, behavior, fabrication, and use

  14. Radiation damage to electronic components

    International Nuclear Information System (INIS)

    Battisti, S.; Bossart, R.; Schoenbacher, H.; Van de Voorde, M.

    1975-01-01

    Characteristic properties are presented of some 40 different electronic components (resistors, capacitors, diodes, transistors, and integrated circuits) which were irradiated in a nuclear reactor up to 1015 n/cm 2 (E > 1 MeV). Complete circuits (e.g. RF amplifiers and detectors, mixers, differential amplifiers, voltage-to-frequency converters, oscillators, power supplies) were irradiated near the CERN Intersecting Storage Rings up to 106 rad(RPL) (dose measured with radiophotoluminescent dosimeters) under simulated operational conditions. Representative measured parameters, such as resistance, capacitance, forward voltage, reverse current, toggle frequencies, are given in graphs as a function of radiation dose. The results are discussed in detail and lead to the over-all conclusion that the operation of electronic components and circuits is seriously affected by radiation environments with doses in the order of 10 13 n/cm 2 or 10 4 rad(RPL); some components and circuits fail completely at doses of 10 14 n/cm 2 or 10 5 rad(RPL). (Author)

  15. Trends in chassis and automobile electronics components

    Energy Technology Data Exchange (ETDEWEB)

    Hackenberg, Ulrich [Volkswagen AG, Wolfsburg (Germany)

    2008-07-01

    The rapidly-growing importance of electronics in automobile construction is in part determined by the debate on sustainability and the clear trend towards electric power trains. Another factor, however, is the decisive impact of electronics on the further development of components, e.g. for chassis. Apart from environmental protection, key motivators for component development include comfort, safety, infotainment and driver assistance. (orig.)

  16. IUE observations of the hot components in two symbiotic stars. [R Agr and RW Hya, 1200 to 3200 A

    Energy Technology Data Exchange (ETDEWEB)

    Michalitsianos, A G [National Aeronautics and Space Administration, Greenbelt, MD (USA). Goddard Space Flight Center; Kafatos, M; Hobbs, R W; Maran, S P

    1980-03-13

    Ultraviolet measurements in the 1,200 - 3,200 A range are reported on two symbiotic stars, R Agr and RW Hya. The results indicate the presence of a hot component in each star, supporting the view that each is a binary system with a luminous red primary and a hot, sub-luminous companion. In the case of RW Hya the hot companion manifests itself by exciting a compact nebulosity while in the case of R Agr it is believed that the continuous spectrum of the hot star is directly detected, while the continuum of nebulosity excited by the hot star is detected at longer wavelengths.

  17. Generation and Transport of Hot Electrons in Cone-Wire Targets

    Science.gov (United States)

    Beg, Farhat

    2009-11-01

    We present results from a series of experiments where cone-wire targets in various configurations were employed both to assess hot electron coupling efficiency, and to reveal the source temperature of the hot electrons. Initial experiments were performed on the Vulcan petawatt laser at the Rutherford Appleton Laboratory and Titan laser at the Lawrence Livermore National Laboratory. Results with aluminum cones joined to Cu wires of diameters from 10 to 40 μm show that the laser coupling efficiency to electron energy within the wire is proportional to the cross sectional area of the wire. In addition, coupling into the wire was observed to decrease with the laser prepulse and cone-wall thickness. More recently, this study was extended, using the OMEGA EP laser. The resulting changes in coupling energy give indications of the scaling as we approach FI-relevant conditions. Requirements for FI scale fast ignition cone parameters: tip thickness, wall thickness, laser prepulse and laser pulse length, will be discussed. In collaboration with T. Yabuuchi, T. Ma, D. Higginson, H. Sawada, J. King, M.H. Key, K.U. Akli, Al Elsholz, D. Batani, H. Chen, R.R. Freeman, L. Gizzi, J. Green, S. Hatchett, D. Hey, P. Jaanimagi, J. Koch, K. L. Lancaster, D.Larson, A.J. MacKinnon, H. McLean, A. MacPhee, P.A. Norreys, P.K Patel, R. B. Stephens, W. Theobald, R. Town, M. Wei, S. Wilks, Roger Van Maren, B. Westover and L. VanWoerkom.

  18. An Ultrasensitive Hot-Electron Bolometer for Low-Background SMM Applications

    Science.gov (United States)

    Olayaa, David; Wei, Jian; Pereverzev, Sergei; Karasik, Boris S.; Kawamura, Jonathan H.; McGrath, William R.; Sergeev, Andrei V.; Gershenson, Michael E.

    2006-01-01

    We are developing a hot-electron superconducting transition-edge sensor (TES) that is capable of counting THz photons and operates at T = 0.3K. The main driver for this work is moderate resolution spectroscopy (R approx. 1000) on the future space telescopes with cryogenically cooled (approx. 4 K) mirrors. The detectors for these telescopes must be background-limited with a noise equivalent power (NEP) approx. 10(exp -19)-10(exp -20) W/Hz(sup 1/2) over the range v = 0.3-10 THz. Above about 1 THz, the background photon arrival rate is expected to be approx. 10-100/s), and photon counting detectors may be preferable to an integrating type. We fabricated superconducting Ti nanosensors with a volume of approx. 3x10(exp -3) cubic microns on planar substrate and have measured the thermal conductance G to the thermal bath. A very low G = 4x10(exp -14) W/K, measured at 0.3 K, is due to the weak electron-phonon coupling in the material and the thermal isolation provided by superconducting Nb contacts. This low G corresponds to NEP(0.3K) = 3x10(exp -19) W/Hz(sup 1/2). This Hot-Electron Direct Detector (HEDD) is expected to have a sufficient energy resolution for detecting individual photons with v > 0.3 THz at 0.3 K. With the sensor time constant of a few microseconds, the dynamic range is approx. 50 dB.

  19. Utilizing hot electrons

    Energy Technology Data Exchange (ETDEWEB)

    Nozik, Arthur J.

    2018-03-01

    In current solar cells, any photon energy exceeding the semiconductor bandgap is lost before being collected, limiting the cell performance. Hot carrier solar cells could avoid these losses. Now, a detailed experimental study and analysis shows that this strategy could lead to an improvement of the photoconversion efficiency in practice.

  20. Origins and Scaling of Hot-Electron Preheat in Ignition-Scale Direct-Drive Inertial Confinement Fusion Experiments.

    Science.gov (United States)

    Rosenberg, M J; Solodov, A A; Myatt, J F; Seka, W; Michel, P; Hohenberger, M; Short, R W; Epstein, R; Regan, S P; Campbell, E M; Chapman, T; Goyon, C; Ralph, J E; Barrios, M A; Moody, J D; Bates, J W

    2018-02-02

    Planar laser-plasma interaction (LPI) experiments at the National Ignition Facility (NIF) have allowed access for the first time to regimes of electron density scale length (∼500 to 700  μm), electron temperature (∼3 to 5 keV), and laser intensity (6 to 16×10^{14}  W/cm^{2}) that are relevant to direct-drive inertial confinement fusion ignition. Unlike in shorter-scale-length plasmas on OMEGA, scattered-light data on the NIF show that the near-quarter-critical LPI physics is dominated by stimulated Raman scattering (SRS) rather than by two-plasmon decay (TPD). This difference in regime is explained based on absolute SRS and TPD threshold considerations. SRS sidescatter tangential to density contours and other SRS mechanisms are observed. The fraction of laser energy converted to hot electrons is ∼0.7% to 2.9%, consistent with observed levels of SRS. The intensity threshold for hot-electron production is assessed, and the use of a Si ablator slightly increases this threshold from ∼4×10^{14} to ∼6×10^{14}  W/cm^{2}. These results have significant implications for mitigation of LPI hot-electron preheat in direct-drive ignition designs.

  1. Analysis of a High-Tc Hot-Electron Superconducting Mixer for Terahertz Applications

    Science.gov (United States)

    Karasik, B. S.; McGrath, W. R.; Gaidis, M. C.

    1996-01-01

    The prospects of a YBa2Cu3O7(delta)(YBCO) hot-electron bolometer (HEB) mixer for a THz heterodyne receiver is discussed. The modeled device is a submicron bridge made from a 10 nm thick film on a high thermal conductance substrate.

  2. Hot electron effect in the dc SQUID

    International Nuclear Information System (INIS)

    Wellstood, F.C.; Clarke, J.; Urbina, C.

    1989-01-01

    The authors have investigated the temperature dependence of the noise in thin-film dc Superconducting Quantum Interference Devices (SQUIDs) down to 20 mK. The white noise measured in the early versions of our SQUIDs did not decrease as the bath temperature was lowered below 150 mK. They have attributed this saturation to a hot electron effect in the thin-film AuCu resistors shunting the Josephson junctions. A theoretical investigation showed that the temperature of the electrons in the shunts should be given by T/sub e/ = (P/ΣΩ)/sup 1/5/, where P is the power dissipated in the shunts, Ω is the shunt volume, and Σ is a proportionality constant. Experimentally, the authors found Σ=(2.4+-0.6)X10/sup 9/WK/sup -5/m/sup -3/. They have redesigned the shunts, adding large thin-film cooling fins, to increase their volume substantially. This technique has reduced T/sub e/ to about 50 mK, with a corresponding improvement in the sensitivity of the SQUIDs

  3. Transistor electronics use of semiconductor components in switching operations

    CERN Document Server

    Rumpf, Karl-Heinz

    2014-01-01

    Transistor Electronics: Use of Semiconductor Components in Switching Operations presents the semiconductor components as well as their elementary circuits. This book discusses the scope of application of electronic devices to increase productivity. Organized into eight chapters, this book begins with an overview of the general equation for the representation of integer positive numbers. This text then examines the properties and characteristics of basic electronic components, which relates to an understanding of the operation of semiconductors. Other chapters consider the electronic circuit ar

  4. Fabrication of High-T(sub c) Hot-Electron Bolometric Mixers for Terahertz Applications

    Science.gov (United States)

    Burns, M. J.; Kleinsasser, A. W.; Delin, K. A.; Vasquez, R. P.; Karasik, B. S.; McGrath, W. R.; Gaidis, M. C.

    1996-01-01

    Superocnducting hot-electron bolometers (HEB) represent a promising candidate for heterodyne mixing at frequencies exceeding 1 THz. Nb HEB mixers offer performance competitive with tunnel junctions without the frequency limit imposed by the superconducting energy gap.

  5. Design of nanophotonic, hot-electron solar-blind ultraviolet detectors with a metal-oxide-semiconductor structure

    International Nuclear Information System (INIS)

    Wang, Zhiyuan; Wang, Xiaoxin; Liu, Jifeng

    2014-01-01

    Solar-blind ultraviolet (UV) detection refers to photon detection specifically in the wavelength range of 200 nm–320 nm. Without background noises from solar radiation, it has broad applications from homeland security to environmental monitoring. The most commonly used solid state devices for this application are wide band gap (WBG) semiconductor photodetectors (Eg > 3.5 eV). However, WBG semiconductors are difficult to grow and integrate with Si readout integrated circuits (ROICs). In this paper, we design a nanophotonic metal-oxide-semiconductor structure on Si for solar-blind UV detectors. Instead of using semiconductors as the active absorber, we use Sn nano-grating structures to absorb UV photons and generate hot electrons for internal photoemission across the Sn/SiO 2 interfacial barrier, thereby generating photocurrent between the metal and the n-type Si region upon UV excitation. Moreover, the transported hot electron has an excess kinetic energy >3 eV, large enough to induce impact ionization and generate another free electron in the conduction band of n-Si. This process doubles the quantum efficiency. On the other hand, the large metal/oxide interfacial energy barrier (>3.5 eV) also enables solar-blind UV detection by blocking the less energetic electrons excited by visible photons. With optimized design, ∼75% UV absorption and hot electron excitation can be achieved within the mean free path of ∼20 nm from the metal/oxide interface. This feature greatly enhances hot electron transport across the interfacial barrier to generate photocurrent. The simple geometry of the Sn nano-gratings and the MOS structure make it easy to fabricate and integrate with Si ROICs compared to existing solar-blind UV detection schemes. The presented device structure also breaks through the conventional notion that photon absorption by metal is always a loss in solid-state photodetectors, and it can potentially be extended to other active metal photonic devices. (paper)

  6. Measurements of the ballistic-phonon component resulting from nuclear and electron recoils in crystalline silicon

    International Nuclear Information System (INIS)

    Lee, A.T.; Cabrera, B.; Dougherty, B.L.; Penn, M.J.; Pronko, J.G.; Tamura, S.

    1996-01-01

    We present measurements of the ballistic-phonon component resulting from nuclear and electron recoils in silicon at ∼380 mK. The detectors used for these experiments consist of a 300-μm-thick monocrystal of silicon instrumented with superconducting titanium transition-edge sensors. These sensors detect the initial wavefront of athermal phonons and give a pulse height that is sensitive to changes in surface-energy density resulting from the focusing of ballistic phonons. Nuclear recoils were generated by neutron bombardment of the detector. A Van de Graaff proton accelerator and a thick 7 Li target were used. Pulse-height spectra were compared for neutron, x-ray, and γ-ray events. A previous analysis of this data set found evidence for an increase in the ballistic-phonon component for nuclear recoils compared to electron recoils at a 95% confidence level. An improved understanding of the detector response has led to a change in the result. In the present analysis, the data are consistent with no increase at the 68% confidence level. This change stems from an increase in the uncertainty of the result rather than a significant change in the central value. The increase in ballistic phonon energy for nuclear recoils compared to electron recoils as a fraction of the total phonon energy (for equal total phonon energy events) was found to be 0.024 +0.041 -0.055 (68% confidence level). This result sets a limit of 11.6% (95% confidence level) on the ballistic phonon enhancement for nuclear recoils predicted by open-quote open-quote hot spot close-quote close-quote and electron-hole droplet models, which is the most stringent to date. To measure the ballistic-phonon component resulting from electron recoils, the pulse height as a function of event depth was compared to that of phonon simulations. (Abstract Truncated)

  7. Identification of conduction and hot electron property in ZnS, ZnO and SiO2

    International Nuclear Information System (INIS)

    Huang Jinzhao; Xu Zheng; Zhao Suling; Li Yuan; Yuan Guangcai; Wang Yongsheng; Xu Xurong

    2007-01-01

    The impact excitation and ionization is the most important process in layered optimization scheme and solid state cathodoluminescence. The conduction property (semiconductor property) of SiO 2 , ZnS and ZnO is studied based on organic/inorganic electroluminescence. The hot electron property (acceleration and multiplication property) of SiO 2 and ZnS is investigated based on the solid state cathodoluminescence. The results show that the SiO 2 has the fine hot electron property and the conduction property is not as good as ZnO and ZnS

  8. Reliable determination of the Cu/n-Si Schottky barrier height by using in-device hot-electron spectroscopy

    International Nuclear Information System (INIS)

    Parui, Subir; Atxabal, Ainhoa; Ribeiro, Mário; Bedoya-Pinto, Amilcar; Sun, Xiangnan; Llopis, Roger; Casanova, Fèlix; Hueso, Luis E.

    2015-01-01

    We show the operation of a Cu/Al 2 O 3 /Cu/n-Si hot-electron transistor for the straightforward determination of a metal/semiconductor energy barrier height even at temperatures below carrier-freeze out in the semiconductor. The hot-electron spectroscopy measurements return a fairly temperature independent value for the Cu/n-Si barrier of 0.66 ± 0.04 eV at temperatures below 180 K, in substantial accordance with mainstream methods based on complex fittings of either current-voltage (I-V) and capacitance-voltage (C-V) measurements. The Cu/n-Si hot-electron transistors exhibit an OFF current of ∼2 × 10 −13  A, an ON/OFF ratio of ∼10 5 , and an equivalent subthreshold swing of ∼96 mV/dec at low temperatures, which are suitable values for potential high frequency devices

  9. All-inorganic perovskite nanocrystal assisted extraction of hot electrons and biexcitons from photoexcited CdTe quantum dots.

    Science.gov (United States)

    Mondal, Navendu; De, Apurba; Samanta, Anunay

    2018-01-03

    Excitation of semiconductor quantum dots (QDs) by photons possessing energy higher than the band-gap creates a hot electron-hole pair, which releases its excess energy as waste heat or under certain conditions (when hν > 2E g ) produces multiple excitons. Extraction of these hot carriers and multiple excitons is one of the key strategies for enhancing the efficiency of QD-based photovoltaic devices. However, this is a difficult task as competing carrier cooling and relaxation of multiple excitons (through Auger recombination) are ultrafast processes. Herein, we study the potential of all-inorganic perovskite nanocrystals (NCs) of CsPbX 3 (X = Cl, Br) as harvesters of these short-lived species from photo-excited CdTe QDs. The femtosecond transient absorption measurements show CsPbX 3 mediated extraction of both hot and thermalized electrons of the QDs (under a low pump power) and (under a high pump fluence) extraction of multiple excitons prior to their Auger assisted recombination. A faster timescale of thermalized electron transfer (∼2 ps) and a higher extraction efficiency of hot electrons (∼60%) are observed in the presence of CsPbBr 3 . These observations demonstrate the potential of all-inorganic perovskite NCs in the extraction of these short-lived energy rich species implying that complexes of the QDs and perovskite NCs are better suited for improving the efficiency of QD-sensitized solar cells.

  10. Reliable determination of the Cu/n-Si Schottky barrier height by using in-device hot-electron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Parui, Subir, E-mail: s.parui@nanogune.eu, E-mail: l.hueso@nanogune.eu; Atxabal, Ainhoa; Ribeiro, Mário; Bedoya-Pinto, Amilcar; Sun, Xiangnan; Llopis, Roger [CIC nanoGUNE, 20018 Donostia-San Sebastian, Basque Country (Spain); Casanova, Fèlix; Hueso, Luis E., E-mail: s.parui@nanogune.eu, E-mail: l.hueso@nanogune.eu [CIC nanoGUNE, 20018 Donostia-San Sebastian, Basque Country (Spain); IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Basque Country (Spain)

    2015-11-02

    We show the operation of a Cu/Al{sub 2}O{sub 3}/Cu/n-Si hot-electron transistor for the straightforward determination of a metal/semiconductor energy barrier height even at temperatures below carrier-freeze out in the semiconductor. The hot-electron spectroscopy measurements return a fairly temperature independent value for the Cu/n-Si barrier of 0.66 ± 0.04 eV at temperatures below 180 K, in substantial accordance with mainstream methods based on complex fittings of either current-voltage (I-V) and capacitance-voltage (C-V) measurements. The Cu/n-Si hot-electron transistors exhibit an OFF current of ∼2 × 10{sup −13} A, an ON/OFF ratio of ∼10{sup 5}, and an equivalent subthreshold swing of ∼96 mV/dec at low temperatures, which are suitable values for potential high frequency devices.

  11. A Hot-electron Direct Detector for Radioastronomy

    Science.gov (United States)

    Karasik, B. S.; McGrath, W. R.; LeDuc, H. G.

    2000-01-01

    A new approach is proposed to improve the sensitivity of direct-detection bolometers. The idea is to adjust a speed of the thermal relaxation of hot-electrons in a nanometer size normal metal or superconductive transition edge bolometer by controlling the elastic electron mean free path. If the bolometer contacts are made of a superconductor with high critical temperature then the thermal diffusion into the contacts is absent because of the Andreev's reflection and the electron-phonon relaxation is the only mechanism for heat removal. The relaxation rate should behave as 7(exp 4)l at subkelvin temperatures (l is the electron elastic mean free path) and can be reduced by factor of 10 - 100 by decreasing l. Then an antenna- or waveguide-coupled bolometer with a time constant approx. 10(exp -3) to 10(exp -5) S at T approx. = 0.1 - 0.3 K will exhibit photon-noise limited performance in millimeter and subn-millimeter range. The bolometer will have a figure-of-merit NEk square root of tau approx. = 10(exp -22) 10(exp -21) W/Hz at 100 mK which is 10(exp 3) times smaller than that of a state-of-the-art bolometer. This will allow for a tremendous increase in speed which will have a significant impact for observational mapping applications. Alternatively, the bolometer could operate at higher temperature with still superior sensitivity This research was performed by the Center for Space Microelectronics Technology, JPL, California Institute of Technology, under the contract for NASA.

  12. Compatibility and testing of electronic components

    CERN Document Server

    Jowett, C E

    2013-01-01

    Compatibility and Testing of Electronic Components outlines the concepts of component part life according to thresholds of failure; the advantages that result from identifying such thresholds; their identification; and the various tests used in their detection. The book covers topics such as the interconnection of miniature passive components; the integrated circuit compatibility and its components; the semiconductor joining techniques; and the thin film hybrid approach in integrated circuits. Also covered are topics such as thick film resistors, conductors, and insulators; thin inlays for el

  13. Hot Electron Generation and Transport Using Kα Emission

    International Nuclear Information System (INIS)

    Akli, K.U.; Stephens, R.B.; Key, M.H.; Bartal, T.; Beg, F.N.; Chawla, S.; Chen, C.D.; Fedosejevs, R.; Freeman, R.R.; Friesen, H.; Giraldez, E.; Green, J.S.; Hey, D.S.; Higginson, D.P.; Hund, J.; Jarrott, L.C.; Kemp, G.E.; King, J.A.; Kryger, A.; Lancaster, K.; LePape, S.; Link, A.; Ma, T.; Mackinnon, A.J.; MacPhee, A.G.; McLean, H.S.; Murphy, C.; Norreys, P.A.; Ovchinnikov, V.; Patel, P.K.; Ping, Y.; Sawada, H.; Schumacher, D.; Theobald, W.; Tsui, Y.Y.; Van Woerkom, L.D.; Wei, M.S.; Westover, B.; Yabuuchi, T.

    2010-01-01

    We have conducted experiments on both the Vulcan and Titan laser facilities to study hot electron generation and transport in the context of fast ignition. Cu wires attached to Al cones were used to investigate the effect on coupling efficiency of plasma surround and the pre-formed plasma inside the cone. We found that with thin cones 15% of laser energy is coupled to the 40(micro)m diameter wire emulating a 40(micro)m fast ignition spot. Thick cone walls, simulating plasma in fast ignition, reduce coupling by x4. An increase of prepulse level inside the cone by a factor of 50 reduces coupling by a factor of 3.

  14. Fermi-degeneracy and discrete-ion effects in the spherical-cell model and electron-electron correlation effects in hot dense plasmas

    International Nuclear Information System (INIS)

    Furukawa, H.; Nishihara, K.

    1992-01-01

    The spherical-cell model [F. Perrot, Phys. Rev. A 25, 489 (1982); M. W. C. Dharma-wardana and F. Perrot, ibid. 26, 2096 (1982)] is improved to investigate laser-produced hot, dense plasmas. The free-electron distribution function around a test free electron is calculated by using the Fermi integral in order that the free-electron--free-electron correlation function includes Fermi-degeneracy effects, and also that the calculation includes the discrete-ion effect. The free-electron--free-electron, free-electron--ion, and ion-ion correlation effects are coupled, within the framework of the hypernetted-chain approximation, through the Ornstein-Zernike relation. The effective ion-ion potential includes the effect of a spatial distribution of bound electrons. The interparticle correlation functions and the effective potential acting on either an electron or an ion in hot, dense plasmas are calculated numerically. The Fermi-degeneracy effect on the correlation functions between free electrons becomes clear for the degeneracy parameter θ approx-lt 1. The discrete-ion effect in the calculation of the correlation functions between free electrons affects the electron-ion pair distribution functions for r s approx-gt 3. As an application of the proposed model, the strong-coupling effect on the stopping power of charged particles [Xin-Zhong Yan, S. Tanaka, S. Mitake, and S. Ichimaru, Phys. Rev. A 32, 1785 (1985)] is estimated. While the free-electron--ion strong-coupling effect and the Fermi-degeneracy effect incorporated in the calculation of the free-electron distribution function around a test free electron enhance the stopping number, the quantum-diffraction effect incorporated in the quantal hypernetted-chain equations [J. Chihara, Prog. Theor. Phys. 72, 940 (1984); Phys. Rev. A 44, 1247 (1991); J. Phys. Condens. Matter 3, 8715 (1991)] reduces the stopping number substantially

  15. Formation of hot spots in a superconductor observed by low-temperature scanning electron microscopy

    International Nuclear Information System (INIS)

    Eichele, R.; Seifert, H.; Huebener, R.P.

    1981-01-01

    Low-temperature scanning electron microscopy can be used for the direct observation of hot spots in a superconductor. Experiments performed at 2.10 K with tim films demonstrating the method are reported

  16. Hot phonon generation by split-off hole band electrons in AlxGa1-xAs alloys investigated by picosecond Raman scattering

    International Nuclear Information System (INIS)

    Jacob, J.M.; Kim, D.S.; Zhou, J.F.; Song, J.J.

    1992-01-01

    The initial generation of hot LO phonons by the relaxation of hot carriers in GaAs and Al x Ga 1-x As alloy semiconductors is studied. Within the initial 2ps of photoexcitation, only those electrons originating from the split-off hole bands are found to generate a significant number of I-valley hot phonons when photon energies of 2.33eV are used. A picosecond Raman scattering technique is used to determine the hot phonon occupation number in a series of MBE grown Al x Ga 1-x As samples with 0≤x≤0.39. The Stokes and anti-Stokes lines were measured for both GaAs-like and AlAs-like LO phonon modes to determine their occupation numbers. The authors observe a rapid decrease in the phonon occupation numbers as the aluminum concentration increases beyond x = 0.2. This rapid decrease is explained by considering only those electrons photoexcited from the split-off hole band. Almost all of the electrons originating from the heavy and light-hole bands are shown to quickly transfer and remain in the X and L valleys without generating significant numbers of hot LO phonons during the initial 2ps and at a carrier density of 10 17 cm -3 . A model based upon the instantaneous thermalization of hot electrons photoexcited from the split-off hole bands is used to fit the data. They have obtained very good agreement between experiment and theory. This work provides a clear understanding to the relaxation of Γ valley hot electrons by the generation of hot phonons on subpicosecond and picosecond time scales, which has long standing implications to previous time resolved Raman experiments

  17. Interpretation of the electron cyclotron emission of hot ASDEX upgrade plasmas at optically thin frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Denk, Severin Sebastian; Stroth, Ulrich [Max-Planck-Institut fuer Plasmaphysik, D-85748 Garching (Germany); Physik-Department E28, Technische Universitaet Muenchen, 85748 Garching (Germany); Fischer, Rainer; Poli, Emanuele; Willensdorfer, Matthias; Maj, Omar; Stober, Joerg; Suttrop, Wolfgang [Max-Planck-Institut fuer Plasmaphysik, D-85748 Garching (Germany); Collaboration: The ASDEX Upgrade Team

    2016-07-01

    The electron cyclotron emission diagnostic (ECE) provides routinely electron temperature (T{sub e}) measurements. ''Kinetic effects'' (relativistic mass shift and Doppler shift) can cause the measured radiation temperatures (T{sub rad}) to differ from T{sub e} at cold resonance position complicating the determination of T{sub e} from the measured radiation temperature profile (T{sub rad}). For the interpretation of such ECE measurements an electron cyclotron forward model solving the radiation transport equation for given T{sub e} and electron density profiles is in use in the framework of Integrated Data Analysis at ASDEX Upgrade. While the original model lead to improved T{sub e} profiles near the plasma edge in moderately hot H-mode discharges, vacuum approximations in the model lead to inaccuracies given large T{sub e}. In hot plasmas ''wave-plasma interaction'', i.e. the dielectric effect of the background plasma onto the electron cyclotron emission, becomes important at optical thin measured frequencies. Additionally, given moderate electron densities and large T{sub e}, the refraction of the line of sight has to be considered for the interpretation of ECE measurements with low optical depth.

  18. An experimental determination of the hot electron ring geometry in a Bumpy Torus and its implications for Bumpy Torus stability

    International Nuclear Information System (INIS)

    Hillis, D.L.; Wilgen, J.B.; Bigelow, T.S.; Jaeger, E.F.; Swain, D.W.; Hankins, O.E.; Juhala, R.E.

    1986-10-01

    The hot electron rings of the ELMO Bumpy Torus (EBT) [Plasma Physics and Controlled Nuclear Fusion (IAEA, Vienna, 1975), Vol. II, p. 141] are formed by electron cyclotron resonance heating (ECRH) and have an electron temperature of 350 to 500 keV. The original intention of these hot electron rings was to provide a local minimum in the magnetic field and, thereby, stabilize the simple interchange and flute modes, which are inherent in a closed field line bumpy torus. To evaluate the electron energy density of the EBT rings and determine if enough stored energy is present to provide a local minimum in the magnetic field, a detailed understanding of the spatial distribution of the rings is imperative. The purpose of this report is to measure the ring thickness and investigate its implications for bumpy torus stability. The spatial location and radial profile of the hot electron ring are measured with a unique metal ball pellet injector, which injects small metallic balls into the EBT ring plasma. From these measurements the radial extent (or ring thickness) is about 5 to 7 cm full width at half maximum for typical EBT operation, which is much larger than previously expected. These measurements and recent modeling of the EBT plasma indicate that the hot electron ring's stored energy may not be sufficient to produce a local minimum in the magnetic field

  19. Fundamental harmonic electron cyclotron emission for hot, loss-cone type distributions

    International Nuclear Information System (INIS)

    Bornatici, M.; Ruffina, U.; Westerhof, E.

    1988-01-01

    Electron cyclotron emission (ECE) is an important diagnostic tool for the study of hot plasmas. ECE can be used not only to measure the electron temperature but also to obtain information about non-thermal characteristics of the electron distribution function. One such a nonthermal characteristic is a loss-cone anisotropy. Loss-cone anisotropy can give rise to unstable growth of electro-magnetic waves around the harmonics of the electron cyclotron resonance and to increased emissivity of electron cyclotron waves. In case of high electron temperatures, also the dispersion properties of the extraordinary (X-) mode arond the fundamental electron cyclotron resonance are changed due to loss-cone anisotropy. The consequences of these dispersion properties for the emissivity of the fundamental harmonic X-mode are analyzed for perpendicular propagation. The emissivity, is calculated for two types of distribution functions having a loss-cone anisotropy. These distribution functions are a relativistic Dory-Guest-Harris type distribution function and modified relativistic Maxwellian distribution having a loss-cone with rounded edges (author). 9 refs.; 2 figs

  20. AECL hot-cell facilities and post-irradiation examination services

    International Nuclear Information System (INIS)

    Schankula, M.H.; Plaice, E.L.; Woodworth, L.G.

    1998-04-01

    This paper presents an overview of the post-irradiation examination (PIE) services available at AECL's hot-cell facilities (HCF). The HCFs are used primarily to provide PIE support for operating CANDU power reactors in Canada and abroad, and for the examination of experimental fuel bundles and core components irradiated in research reactors at the Chalk River Laboratories (CRL) and off-shore. A variety of examinations and analyses are performed ranging from non-destructive visual and dimensional inspections to detailed optical and scanning electron microscopic examinations. Several hot cells are dedicated to mechanical property testing of structural materials and to determine the fitness-for-service of reactor core components. Facility upgrades and the development of innovative examination techniques continue to improve AECL's PIE capabilities. (author)

  1. AECL hot-cell facilities and post-irradiation examination services

    International Nuclear Information System (INIS)

    Schankula, M.H.; Plaice, E.L.; Woodworth, L.G.

    1995-01-01

    This paper presents an overview of the post-irradiation examination (PIE) services available at AECL's hot-cell facilities (HCF). The HCFs are used primarily to provide PIE support for operating CANDU power reactors in Canada and abroad, and for the examination of experimental fuel bundles and core components irradiated in research reactors at the Chalk River Laboratories (CRL) and off-shore. A variety of examinations and analysis are performed ranging from non-destructive visual and dimensional inspections to detailed optical and scanning electron microscopic examinations. Several hot cells are dedicated to mechanical property testing of structural materials and to determine the fitness-for-service of reactor core components. Facility upgrades and the development of innovative examination techniques continue to improve AECL's PIE capabilities. (author)

  2. The influence of microstructure and operating temperature on the fatigue endurance of hot forged Inconel{sup ®} 718 components

    Energy Technology Data Exchange (ETDEWEB)

    Maderbacher, H., E-mail: hermann.maderbacher@unileoben.ac.at [Chair of Mechanical Engineering, Montanuniversität Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria); Oberwinkler, B., E-mail: bernd.oberwinkler@bohler-forging.com [Böhler Schmiedetechnik GmbH and Co KG, Mariazellerstraße 25, 8605 Kapfenberg (Austria); Gänser, H.-P., E-mail: hans-peter.gaenser@mcl.at [Materials Center Leoben Forschung GmbH, Roseggerstraße 12, 8700 Leoben (Austria); Tan, W., E-mail: wen.tan@unileoben.ac.at [Chair of Mechanical Engineering, Montanuniversität Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria); Rollett, M., E-mail: mathias.rollett@stud.unileoben.ac.at [Chair of Mechanical Engineering, Montanuniversität Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria); Stoschka, M., E-mail: michael.stoschka@stud.unileoben.ac.at [Chair of Mechanical Engineering, Montanuniversität Leoben, Franz-Josef-Straße 18, 8700 Leoben (Austria)

    2013-11-15

    The dependence of the fatigue behavior of hot-forged Inconel{sup ®} 718 aircraft components on the operating temperature and the material microstructure is investigated. To this purpose, possible correlations between a variety of tested microstructural parameters and the results from low-cycle fatigue (LCF) testing are analyzed using statistical methods. To identify the prevailing damage mechanisms, failure analyses are carried out on specimens tested at different temperatures. Optical and scanning electron microscopy are used for the inspection of surface crack networks and of the final fracture surface. In addition, energy dispersive X-ray (EDX) analyses are performed at the crack initiation sites to track down possible accumulations of alloying elements. The results are critically reviewed and used to propose a temperature and microstructure dependent fatigue model for predicting LCF ε⧸N-curves.

  3. Time-resolved measurements of the hot-electron population in ignition-scale experiments on the National Ignition Facility (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Hohenberger, M., E-mail: mhoh@lle.rochester.edu; Stoeckl, C. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Albert, F.; Palmer, N. E.; Döppner, T.; Divol, L.; Dewald, E. L.; Bachmann, B.; MacPhee, A. G.; LaCaille, G.; Bradley, D. K. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Lee, J. J. [National Security Technologies LLC, Livermore, California 94551 (United States)

    2014-11-15

    In laser-driven inertial confinement fusion, hot electrons can preheat the fuel and prevent fusion-pellet compression to ignition conditions. Measuring the hot-electron population is key to designing an optimized ignition platform. The hot electrons in these high-intensity, laser-driven experiments, created via laser-plasma interactions, can be inferred from the bremsstrahlung generated by hot electrons interacting with the target. At the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)], the filter-fluorescer x-ray (FFLEX) diagnostic–a multichannel, hard x-ray spectrometer operating in the 20–500 keV range–has been upgraded to provide fully time-resolved, absolute measurements of the bremsstrahlung spectrum with ∼300 ps resolution. Initial time-resolved data exhibited significant background and low signal-to-noise ratio, leading to a redesign of the FFLEX housing and enhanced shielding around the detector. The FFLEX x-ray sensitivity was characterized with an absolutely calibrated, energy-dispersive high-purity germanium detector using the high-energy x-ray source at NSTec Livermore Operations over a range of K-shell fluorescence energies up to 111 keV (U K{sub β}). The detectors impulse response function was measured in situ on NIF short-pulse (∼90 ps) experiments, and in off-line tests.

  4. Target Surface Area Effects on Hot Electron Dynamics from High Intensity Laser-Plasma Interactions

    Science.gov (United States)

    2016-08-19

    Science, University ofMichigan, AnnArbor,MI 48109-2099, USA E-mail: czulick@umich.edu Keywords: laser- plasma ,mass-limited, fast electrons , sheath...New J. Phys. 18 (2016) 063020 doi:10.1088/1367-2630/18/6/063020 PAPER Target surface area effects on hot electron dynamics from high intensity laser... plasma interactions CZulick, ARaymond,AMcKelvey, VChvykov, AMaksimchuk, AGRThomas, LWillingale, VYanovsky andKKrushelnick Center forUltrafast Optical

  5. Buildup of electrons with hot electron beam injection into a homogeneous magnetic field

    International Nuclear Information System (INIS)

    Bashko, V.A.; Krivoruchko, A.M.; Tarasov, I.K.

    1989-01-01

    The injection of the monoenergetic beam of electrons into the vacuum drift channel under the conditions when the beam current exceeds a certain threshold value involves a virtual cathode creation. The process of virtual cathode creation leads to an exchange of one-fluid movement of beam particles to three-fluid one corresponding to incident, reflected and passed through anticathode beam particles. For the monoenergetic beam case when the velocity spread Δv dr (v dr is the beam drift velocity), the beam instability was predicted in theory and was observed in experiment. Meanwhile, the injection in the drift space of the 'hot' beam having finite spread in velocities may be accompanied not only by the reflection of particles if their velocity v 1/2 (where φ is the electrostatic potential dip value, e and m are the electron charge and mass, respectively), but also the mutual Coulomb scattering of incident and reflected electrons. The scattering process leads in its turn to appearance of viscosity forces and to trapping of a part of beam electrons into the effective potential well formed by electrostatic potential dip and the viscous force potential. The interaction of travelling and trapped particles may occur even at the stage preceding the virtual electrode formation and it may influence the process of its appearance and also the current flow through the drift space. In this report there are described the experimental results on accumulation of electrons when electron beam propagates in vacuum and has a large spread in particle velocities Δv dr in the homogeneous longitudinal magnetic field when ω pe He where ω pe is the electron Langmuir frequency of beam electrons, ω He is the electron cyclotron frequency. (author) 6 refs., 2 figs

  6. Hot electron and real space transfer in double-quantum-well structures

    International Nuclear Information System (INIS)

    Okuno, Eiichi; Sawaki, Nobuhiko; Akasaki, Isamu; Kano, Hiroyuki; Hashimoto, Masafumi.

    1991-01-01

    The hot electron phenomena and real space transfer (RST) effect are studied in GaAs/AlGaAs double-quantum-well (DQW) structures, in which we have two kind of quantum wells with different widths. The drift velocity and the electron temperature at liquid helium temperature are investigated as a function of the external electric field applied parallel to the heterointerface. By increasing the field, the electron temperature rises and reaches a plateau in the intermediate region, followed by further rise in the high-field region. The appearance of the plateau is attributed to the RST effect between the two quantum wells. The threshold field for the appearance of the plateau is determined by the difference energy between the quantized levels in two wells. The energy loss rate as a function of the electron temperature indicates that the RST is assisted by LO phonon scattering. (author)

  7. Broadband Cooling Spectra of Hot Electrons and Holes in PbSe Quantum Dots

    NARCIS (Netherlands)

    Spoor, F.C.M.; Tomić, Stanko; Houtepen, A.J.; Siebbeles, L.D.A.

    2017-01-01

    Understanding cooling of hot charge carriers in semiconductor quantum dots (QDs) is of fundamental interest and useful to enhance the performance of QDs in photovoltaics. We study electron and hole cooling dynamics in PbSe QDs up to high energies where carrier multiplication occurs. We

  8. Electron - polar acoustical phonon interactions in nitride based diluted magnetic semiconductor quantum well via hot electron magnetotransport

    International Nuclear Information System (INIS)

    Pandya, Ankur; Shinde, Satyam; Jha, Prafulla K.

    2015-01-01

    In this paper the hot electron transport properties like carrier energy and momentum scattering rates and electron energy loss rates are calculated via interactions of electrons with polar acoustical phonons for Mn doped BN quantum well in BN nanosheets via piezoelectric scattering and deformation potential mechanisms at low temperatures with high electric field. Electron energy loss rate increases with the electric field. It is observed that at low temperatures and for low electric field the phonon absorption is taking place whereas, for sufficient large electric field, phonon emission takes place. Under the piezoelectric (polar acoustical phonon) scattering mechanism, the carrier scattering rate decreases with the reduction of electric field at low temperatures wherein, the scattering rate variation with electric field is limited by a specific temperature beyond which there is no any impact of electric field on such scattering

  9. Scanning electron microscopy and transmission electron microscopy study of hot-deformed gamma-TiAl-based alloy microstructure.

    Science.gov (United States)

    Chrapoński, J; Rodak, K

    2006-09-01

    The aim of this work was to assess the changes in the microstructure of hot-deformed specimens made of alloys containing 46-50 at.% Al, 2 at.% Cr and 2 at.% Nb (and alloying additions such as carbon and boron) with the aid of scanning electron microscopy and transmission electron microscopy techniques. After homogenization and heat treatment performed in order to make diverse lamellae thickness, the specimens were compressed at 1000 degrees C. Transmission electron microscopy examinations of specimens after the compression test revealed the presence of heavily deformed areas with a high density of dislocation. Deformation twins were also observed. Dynamically recrystallized grains were revealed. For alloys no. 2 and no. 3, the recovery and recrystallization processes were more extensive than for alloy no. 1.

  10. Hot accretion disks with electron-positron pairs

    International Nuclear Information System (INIS)

    White, T.R.; Lightman, A.P.

    1989-01-01

    The hot thermal accretion disks of the 1970s are studied and consideration is given to the effects of electron-positron pairs, which were originally neglected. It is found that disks cooled by internally produced photons have a critical accretion rate above which equilibrium is not possible in a radial annulus centered around r = 10 GM/c-squared, where M is the mass of the central object. This confirms and extends previous work by Kusunose and Takahara. Above the critical rate, pairs are created more rapidly than they can be destroyed. Below the critical rate, there are two solutions to the disk structure, one with a high pair density and one with a low pair density. Depending on the strength of the viscosity, the critical accretion rate corresponds to a critical luminosity of about 3-10 percent of the Eddington limit. 32 refs

  11. Study of nonlinear electron-acoustic solitary and shock waves in a dissipative, nonplanar space plasma with superthermal hot electrons

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jiu-Ning, E-mail: hanjiuning@126.com; He, Yong-Lin; Luo, Jun-Hua; Nan, Ya-Gong; Han, Zhen-Hai; Dong, Guang-Xing [College of Physics and Electromechanical Engineering, Hexi University, Zhangye 734000 (China); Duan, Wen-Shan [College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou 730070 (China); Li, Jun-Xiu [College of Civil Engineering, Hexi University, Zhangye 734000 (China)

    2014-01-15

    With the consideration of the superthermal electron distribution, we present a theoretical investigation about the nonlinear propagation of electron-acoustic solitary and shock waves in a dissipative, nonplanar non-Maxwellian plasma comprised of cold electrons, superthermal hot electrons, and stationary ions. The reductive perturbation technique is used to obtain a modified Korteweg-de Vries Burgers equation for nonlinear waves in this plasma. We discuss the effects of various plasma parameters on the time evolution of nonplanar solitary waves, the profile of shock waves, and the nonlinear structure induced by the collision between planar solitary waves. It is found that these parameters have significant effects on the properties of nonlinear waves and collision-induced nonlinear structure.

  12. Non-equilibrium between ions and electrons inside hot spots from National Ignition Facility experiments

    OpenAIRE

    Zhengfeng Fan; Yuanyuan Liu; Bin Liu; Chengxin Yu; Ke Lan; Jie Liu

    2017-01-01

    The non-equilibrium between ions and electrons in the hot spot can relax the ignition conditions in inertial confinement fusion [Fan et al., Phys. Plasmas 23, 010703 (2016)], and obvious ion-electron non-equilibrium could be observed by our simulations of high-foot implosions when the ion-electron relaxation is enlarged by a factor of 2. On the other hand, in many shots of high-foot implosions on the National Ignition Facility, the observed X-ray enhancement factors due to ablator mixing into...

  13. Optimising mechanical properties of hot forged nickel superalloy 625 components

    Science.gov (United States)

    Singo, Nthambe; Coles, John; Rosochowska, Malgorzata; Lalvani, Himanshu; Hernandez, Jose; Ion, William

    2018-05-01

    Hot forging and subsequent heat treatment were resulting in substandard mechanical properties of nickel superalloy, Alloy 625, components. The low strength was found to be due to inadequate deformation during forging, excessive grain growth and precipitation of carbides during subsequent heat treatment. Experimentation in a drop forging company and heat treatment facility led to the establishment of optimal parameters to minimise grain size and mitigate the adverse effects of carbide precipitation, leading to successful fulfilment of mechanical property specifications. This was achieved by reducing the number of operations, maximising the extent of deformation by changing the slug dimensions and its orientation in the die, and minimising the time of exposure to elevated temperatures in both the forging and subsequent heat treatment processes to avoid grain growth.

  14. Hot gas path component having cast-in features for near wall cooling

    Science.gov (United States)

    Miranda, Carlos Miguel; Kottilingam, Srikanth Chandrudu; Lacy, Benjamin Paul

    2018-04-10

    A hot gas path component includes a substrate having an outer surface and an inner surface. The inner surface of the substrate defines at least one interior space. At least a portion of the outer surface of the substrate includes a recess formed therein. The recess includes a bottom surface and a groove extending at least partially along the bottom surface of the recess. A cover is disposed within the recess and covers at least a portion of the groove. The groove is configured to channel a cooling fluid therethrough to cool the cover.

  15. Hot gas path component cooling system having a particle collection chamber

    Science.gov (United States)

    Miranda, Carlos Miguel; Lacy, Benjamin Paul

    2018-02-20

    A cooling system for a hot gas path component includes a substrate having an outer surface and an inner surface. The inner surface defines at least one interior space. A passage is formed in the substrate between the outer surface and the inner surface. An access passage is formed in the substrate and extends from the outer surface to the inner space. The access passage is formed at a first acute angle to the passage and includes a particle collection chamber. The access passage is configured to channel a cooling fluid to the passage. Furthermore, the passage is configured to channel the cooling fluid therethrough to cool the substrate.

  16. Electrically excited hot-electron dominated fluorescent emitters using individual Ga-doped ZnO microwires via metal quasiparticle film decoration.

    Science.gov (United States)

    Liu, Yang; Jiang, Mingming; Zhang, Zhenzhong; Li, Binghui; Zhao, Haifeng; Shan, Chongxin; Shen, Dezhen

    2018-03-28

    The generation of hot electrons from metal nanostructures through plasmon decay provided a direct interfacial charge transfer mechanism, which no longer suffers from the barrier height restrictions observed for metal/semiconductor interfaces. Metal plasmon-mediated energy conversion with higher efficiency has been proposed as a promising alternative to construct novel optoelectronic devices, such as photodetectors, photovoltaic and photocatalytic devices, etc. However, the realization of the electrically-driven generation of hot electrons, and the application in light-emitting devices remain big challenges. Here, hybrid architectures comprising individual Ga-doped ZnO (ZnO:Ga) microwires via metal quasiparticle film decoration were fabricated. The hottest spots could be formed towards the center of the wires, and the quasiparticle films were converted into physically isolated nanoparticles by applying a bias onto the wires. Thus, the hot electrons became spatially localized towards the hottest regions, leading to a release of energy in the form of emitting photons. By adjusting the sputtering times and appropriate alloys, such as Au and Ag, wavelength-tunable emissions could be achieved. To exploit the EL emission characteristics, metal plasmons could be used as active elements to mediate the generation of hot electrons from metal nanostructures, which are located in the light-emitting regions, followed by injection into ZnO:Ga microwire-channels; thus, the production of plasmon decay-induced hot-electrons could function as an efficient approach to dominate emission wavelengths. Therefore, by introducing metal nanostructure decoration, individual ZnO:Ga microwires can be used to construct wavelength-tunable fluorescent emitters. The hybrid architectures of metal-ZnO micro/nanostructures offer a fantastic candidate to broaden the potential applications of semiconducting optoelectronic devices, such as photovoltaic devices, photodetectors, optoelectronic sensors, etc.

  17. Energy relaxation and separation of a hot electron-hole pair in organic aggregates from a time-dependent wavepacket diffusion method

    International Nuclear Information System (INIS)

    Han, Lu; Liang, WanZhen; Zhao, Yi; Zhong, Xinxin

    2014-01-01

    The time-dependent wavepacket diffusive method [X. Zhong and Y. Zhao, J. Chem. Phys. 138, 014111 (2013)] is extended to investigate the energy relaxation and separation of a hot electron-hole pair in organic aggregates with incorporation of Coulomb interaction and electron-phonon coupling. The pair initial condition generated by laser pulse is represented by a Gaussian wavepacket with a central momentum. The results reveal that the hot electron energy relaxation is very well described by two rate processes with the fast rate much larger than the slow one, consistent with experimental observations, and an efficient electron-hole separation is accomplished accompanying the fast energy relaxation. Furthermore, although the extra energy indeed helps the separation by overcoming the Coulomb interaction, the width of initial wavepacket is much sensitive to the separation efficiency and the narrower wavepacket generates the more separated charges. This behavior may be useful to understand the experimental controversy of the hot carrier effect on charge separation

  18. Tribological Behavior of Laser Textured Hot Stamping Dies

    Directory of Open Access Journals (Sweden)

    Andre Shihomatsu

    2016-01-01

    Full Text Available Hot stamping of high strength steels has been continuously developed in the automotive industry to improve mechanical properties and surface quality of stamped components. One of the main challenges faced by researchers and technicians is to improve stamping dies lifetime by reducing the wear caused by high pressures and temperatures present during the process. This paper analyzes the laser texturing of hot stamping dies and discusses how different surfaces textures influence the lubrication and wear mechanisms. To this purpose, experimental tests and numerical simulation were carried out to define the die region to be texturized and to characterize the textured surface topography before and after hot stamping tests with a 3D surface profilometer and scanning electron microscopy. Results showed that laser texturing influences the lubrication at the interface die-hot sheet and improves die lifetime. In this work, the best texture presented dimples with the highest diameter, depth, and spacing, with the surface topography and dimples morphology practically preserved after the hot stamping tests.

  19. An automatic chip structure optical inspection system for electronic components

    Science.gov (United States)

    Song, Zhichao; Xue, Bindang; Liang, Jiyuan; Wang, Ke; Chen, Junzhang; Liu, Yunhe

    2018-01-01

    An automatic chip structure inspection system based on machine vision is presented to ensure the reliability of electronic components. It consists of four major modules, including a metallographic microscope, a Gigabit Ethernet high-resolution camera, a control system and a high performance computer. An auto-focusing technique is presented to solve the problem that the chip surface is not on the same focusing surface under the high magnification of the microscope. A panoramic high-resolution image stitching algorithm is adopted to deal with the contradiction between resolution and field of view, caused by different sizes of electronic components. In addition, we establish a database to storage and callback appropriate parameters to ensure the consistency of chip images of electronic components with the same model. We use image change detection technology to realize the detection of chip images of electronic components. The system can achieve high-resolution imaging for chips of electronic components with various sizes, and clearly imaging for the surface of chip with different horizontal and standardized imaging for ones with the same model, and can recognize chip defects.

  20. Hot electron transport modelling in fast ignition relevant targets with non-Spitzer resistivity

    Energy Technology Data Exchange (ETDEWEB)

    Chapman, D A; Hoarty, D J; Swatton, D J R [Plasma Physics Department, AWE, Aldermaston, Reading, Berkshire, RG7 4PR (United Kingdom); Hughes, S J, E-mail: david.chapman@awe.co.u [Computational Physics Group, AWE, Aldermaston, Reading, Berkshire, RG7 4PR (United Kingdom)

    2010-08-01

    The simple Lee-More model for electrical resistivity is implemented in the hybrid fast electron transport code THOR. The model is shown to reproduce experimental data across a wide range of temperatures using a small number of parameters. The effect of this model on the heating of simple Al targets by a short-pulse laser is studied and compared to the predictions of the classical Spitzer-Haerm resistivity. The model is then used in simulations of hot electron transport experiments using buried layer targets.

  1. Hot gas path component

    Science.gov (United States)

    Lacy, Benjamin Paul; Kottilingam, Srikanth Chandrudu; Porter, Christopher Donald; Schick, David Edward

    2017-09-12

    Various embodiments of the disclosure include a turbomachine component. and methods of forming such a component. Some embodiments include a turbomachine component including: a first portion including at least one of a stainless steel or an alloy steel; and a second portion joined with the first portion, the second portion including a nickel alloy including an arced cooling feature extending therethrough, the second portion having a thermal expansion coefficient substantially similar to a thermal expansion coefficient of the first portion, wherein the arced cooling feature is located within the second portion to direct a portion of a coolant to a leakage area of the turbomachine component.

  2. Numerical study of the generation of runaway electrons in a gas diode with a hot channel

    Energy Technology Data Exchange (ETDEWEB)

    Lisenkov, V. V., E-mail: lisenkov@iep.uran.ru [Institute of Electrophysics UrB RAS, 106 Amundsena St., Ekaterinburg 620012 (Russian Federation); Ural Federal University, 19 Mira St., Ekaterinburg 620002 (Russian Federation); Shklyaev, V. A., E-mail: shklyaev@to.hcei.tsc.ru [Institute of High Current Electronics SD RAS, 2/3 Akademichesky Avenue, 634055 Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 30 Lenin Avenue, 634050 Tomsk (Russian Federation)

    2015-11-15

    A new method for increasing the efficiency of runaway electron beam generation in atmospheric pressure gas media has been suggested and theoretically proved. The method consists of creating a hot region (e.g., a spark channel or a laser plume) with a decreased numerical density of gas molecules (N) near the cathode. In this method, the ratio E/N (E—electric field strength) is increased by decreasing N instead of increasing E, as has been done in the past. The numerical model that is used allows the simultaneous calculation of the formation of a subnanosecond gas discharge and the generation of runaway electrons in gas media. The calculations have demonstrated the possibility of obtaining current pulses of runaway electrons with amplitudes of hundred of amperes and durations of more than 100 ps. The influence of the hot channel geometry on the parameters of the generated beam has been investigated.

  3. Ageing and obsolescence of electronic components

    International Nuclear Information System (INIS)

    Garnero, E.; Daguzan, Ph.; Guillas, J.; Schweitz, G.

    1998-01-01

    Nowadays, every electronic equipment has to cope with two major problems. On the one hand, faster and faster obsolescence of electronic devices is a new trend which happens to prevent users from repairing their boards when parts are no more available. On the other hand, ageing of electronic components can lead to a massive amount of simultaneous failures on huge systems. This phenomenon is unfortunately emphasized when all systems date back to the same period of time. This paper aims at showing the mechanisms involved in these processes. It also describes the solutions found at EDF to face this situation. (authors)

  4. THE HOT COMPONENTS OF AM CVn HELIUM CATACLYSMICS

    International Nuclear Information System (INIS)

    Sion, Edward M.; Godon, Patrick; Ballouz, Ronald-Louis; Linnell, Albert P.

    2011-01-01

    We present the results of a multi-component synthetic spectral analysis of the archival far-ultraviolet spectra of the hot components of several AM CVn double degenerate interacting binaries with known distances from trigonometric parallaxes. Our analysis was carried out using the code BINSYN, which takes into account the donor companion star, the shock front which forms at the disk edge, and the FUV and NUV energy distribution. We fixed the distance of each system at its parallax-derived value and adopted appropriate values of orbital inclination and white dwarf (WD) mass. We find that the accretion-heated 'DO/DB' WDs are contributing significantly to the FUV flux in five of the systems (ES Ceti, CR Boo, V803 Cen, HP Lib, GP Com). In three of the systems, GP Com, ES Ceti, and CR Boo, the WD dominates the FUV/NUV flux. We present model-derived accretion rates which agree with the low end of the range of accretion rates derived earlier from blackbody fits over the entire spectral energy distribution. We find that the WD in ES Ceti is very likely not a direct impact accretor but has a small disk. The WD in ES Ceti has T eff ∼ 40, 000 ± 10, 000 K. This is far cooler than the previous estimate of Espaillat et al.. We find that the WD in GP Com has T eff = 14, 800 ± 500 K, which is hotter than the previously estimated temperature of 11,000 K. We present a comparison between our empirical results and current theoretical predictions for these systems.

  5. Effect of excess superthermal hot electrons on finite amplitude ion-acoustic solitons and supersolitons in a magnetized auroral plasma

    Energy Technology Data Exchange (ETDEWEB)

    Rufai, O. R., E-mail: rrufai@csir.co.za [Council for Scientific and Industrial Research, Pretoria (South Africa); Bharuthram, R., E-mail: rbharuthram@uwc.ac.za [University of the Western Cape, Bellville (South Africa); Singh, S. V., E-mail: satyavir@iigs.iigm.res.in; Lakhina, G. S., E-mail: lakhina@iigs.iigm.res.in [Indian Institute of Geomagnetism, New Panvel (W), Navi, Mumbai-410218 (India)

    2015-10-15

    The effect of excess superthermal electrons is investigated on finite amplitude nonlinear ion-acoustic waves in a magnetized auroral plasma. The plasma model consists of a cold ion fluid, Boltzmann distribution of cool electrons, and kappa distributed hot electron species. The model predicts the evolution of negative potential solitons and supersolitons at subsonic Mach numbers region, whereas, in the case of Cairn's nonthermal distribution model for the hot electron species studied earlier, they can exist both in the subsonic and supersonic Mach number regimes. For the dayside auroral parameters, the model generates the super-acoustic electric field amplitude, speed, width, and pulse duration of about 18 mV/m, 25.4 km/s, 663 m, and 26 ms, respectively, which is in the range of the Viking spacecraft measurements.

  6. Transition-Edge Hot-Electron Microbolometers for Millimeter and Submillimeter Astrophysics

    Science.gov (United States)

    Hsieh, Wen-Ting; Stevenson, Thomas; U-yen, Kongpop; Wollack, Edward; Barrentine, Emily

    2014-01-01

    The millimeter and the submillimeter wavelengths of the electromagnetic spectrum hold a wealth of information about the evolution of the universe. In particular, cosmic microwave background (CMB) radiation and its polarization carry the oldest information in the universe, and provide the best test of the inflationary paradigm available to astronomy today. Detecting gravity waves through their imprint on the CMB polarization would have extraordinary repercussions for cosmology and physics. A transition-edge hot-electron micro - bolometer (THM) consists of a superconducting bilayer transition-edge sensor (TES) with a thin-film absorber. Unlike traditional monolithic bolometers that make use of micromachined structures, the THM em ploys the decoupling between electrons and phonons at millikelvin temperatures to provide thermal isolation. The devices are fabricated photolithographically and are easily integrated with antennas via microstrip transmission lines, and with SQUID (superconducting quantum interference device) readouts. The small volume of the absorber and TES produces a short thermal time constant that facilitates rapid sky scanning. The THM consists of a thin-film metal absorber overlapping a superconducting TES. The absorber forms the termination of a superconducting microstripline that carries RF power from an antenna. The purpose of forming a separate absorber and TES is to allow flexibility in the optimization of the two components. In particular, the absorbing film's impedance can be chosen to match the antenna, while the TES impedance can be chosen to match to the readout SQUID amplifier. This scheme combines the advantages of the TES with the advantages of planar millimeter-wave transmission line circuits. Antenna-coupling to the detectors via planar transmission lines allows the detector dimensions to be much smaller than a wavelength, so the technique can be extended across the entire microwave, millimeter, and submillimeter wavelength ranges. The

  7. Experimental study of hot electrons propagation and energy deposition in solid or laser-shock compressed targets: applications to fast igniter

    International Nuclear Information System (INIS)

    Pisani, F.

    2000-02-01

    In the fast igniter scheme, a recent approach proposed for the inertial confinement fusion, the idea is to dissociate the fuel ignition phase from its compression. The ignition phase would be then achieved by means of an external energy source: a fast electron beam generated by the interaction with an ultra-intense laser. The main goal of this work is to study the mechanisms of the hot electron energy transfer to the compressed fuel. We intent in particular to study the role of the electric and collisional effects involved in the hot electron propagation in a medium with properties similar to the compressed fuel. We carried out two experiments, one at the Vulcan laser facility (England) and the second one at the new LULI 100 TW laser (France). During the first experiment, we obtained the first results on the hot electron propagation in a dense and hot plasma. The innovating aspect of this work was in particular the use of the laser-shock technique to generate high pressures, allowing the strongly correlated and degenerated plasma to be created. The role of the electric and magnetic effects due to the space charge associated with the fast electron beam has been investigated in the second experiment. Here we studied the propagation in materials with different electrical characteristics: an insulator and a conductor. The analysis of the results showed that only by taking into account simultaneously the two propagation mechanisms (collisions and electric effects) a correct treatment of the energy deposition is possible. We also showed the importance of taking into account the induced modifications due to the electrons beam crossing the target, especially the induced heating. (author)

  8. Textile-Based Electronic Components for Energy Applications: Principles, Problems, and Perspective.

    Science.gov (United States)

    Kaushik, Vishakha; Lee, Jaehong; Hong, Juree; Lee, Seulah; Lee, Sanggeun; Seo, Jungmok; Mahata, Chandreswar; Lee, Taeyoon

    2015-09-07

    Textile-based electronic components have gained interest in the fields of science and technology. Recent developments in nanotechnology have enabled the integration of electronic components into textiles while retaining desirable characteristics such as flexibility, strength, and conductivity. Various materials were investigated in detail to obtain current conductive textile technology, and the integration of electronic components into these textiles shows great promise for common everyday applications. The harvest and storage of energy in textile electronics is a challenge that requires further attention in order to enable complete adoption of this technology in practical implementations. This review focuses on the various conductive textiles, their methods of preparation, and textile-based electronic components. We also focus on fabrication and the function of textile-based energy harvesting and storage devices, discuss their fundamental limitations, and suggest new areas of study.

  9. Textile-Based Electronic Components for Energy Applications: Principles, Problems, and Perspective

    Directory of Open Access Journals (Sweden)

    Vishakha Kaushik

    2015-09-01

    Full Text Available Textile-based electronic components have gained interest in the fields of science and technology. Recent developments in nanotechnology have enabled the integration of electronic components into textiles while retaining desirable characteristics such as flexibility, strength, and conductivity. Various materials were investigated in detail to obtain current conductive textile technology, and the integration of electronic components into these textiles shows great promise for common everyday applications. The harvest and storage of energy in textile electronics is a challenge that requires further attention in order to enable complete adoption of this technology in practical implementations. This review focuses on the various conductive textiles, their methods of preparation, and textile-based electronic components. We also focus on fabrication and the function of textile-based energy harvesting and storage devices, discuss their fundamental limitations, and suggest new areas of study.

  10. Evidence of hot spot formation on carbon limiters due to thermal electron emission

    International Nuclear Information System (INIS)

    Philipps, V.; Samm, U.; Tokar, M.Z.; Unterberg, B.; Pospieszczyk, A.; Schweer, B.

    1993-01-01

    Carbon test limiters have been exposed in TEXTOR to high heat loads up to about 30 MW/m 2 . The evolutions of the surface temperature distribution and of the carbon release have been observed by means of local diagnostics. A sudden acceleration of the rise of the surface temperature has been found at a critical temperature of approx. 2400 deg. C. The increase of the rate of the temperature rise is consistent with an enhancement of the power loading by a factor of 2.5-3. Following the temperature jump (hot spot), a quasi-equilibrium temperature establishes at approx. 2700 deg. C. The development of the hot spot is explained by an increase of the local power loading to the breakdown of the sheath potential by thermal emission of electrons from the carbon surface. Simultaneously with the appearance of the hot spot, the carbon release from the surface increases sharply. This increase can be explained by normal thermal sublimation. Sublimation cooling contributes to the establishment of the quasi-equilibrium temperature at about 2700 deg. C. (author). 16 refs, 10 figs

  11. Study by electronic microscopy of corrosion features of graphite after hot oxidation (air, 620 C)

    International Nuclear Information System (INIS)

    Jodon de Villeroche, Suzanne

    1968-01-01

    The author reports the study of corrosion features of graphite after hot oxidation in the air at 620 C. It is based on observations made by electronic microscopy. This study comes after another one dedicated to oxidation features obtained by hot corrosion of natural graphite, and aims at comparing pyrolytic graphite before and after irradiation in an atomic pile, and at performing tests on a graphite processed with ozone. After a recall of generalities about natural graphite and of some issues related to hot corrosion of natural graphite, the author presents some characteristics and features of irradiated and non-irradiated pyrolytic graphite. He reports the study of the oxidation of samples of pyrolytic graphite: production of thin lamellae, production of glaze-carbon replicates, oxidation of irradiated and of non-irradiated graphite, healing of irradiation defects, and oxidation of ozone-processed natural graphite [fr

  12. Arbitrary amplitude slow electron-acoustic solitons in three-electron temperature space plasmas

    International Nuclear Information System (INIS)

    Mbuli, L. N.; Maharaj, S. K.; Bharuthram, R.; Singh, S. V.; Lakhina, G. S.

    2015-01-01

    We examine the characteristics of large amplitude slow electron-acoustic solitons supported in a four-component unmagnetised plasma composed of cool, warm, hot electrons, and cool ions. The inertia and pressure for all the species in this plasma system are retained by assuming that they are adiabatic fluids. Our findings reveal that both positive and negative potential slow electron-acoustic solitons are supported in the four-component plasma system. The polarity switch of the slow electron-acoustic solitons is determined by the number densities of the cool and warm electrons. Negative potential solitons, which are limited by the cool and warm electron number densities becoming unreal and the occurrence of negative potential double layers, are found for low values of the cool electron density, while the positive potential solitons occurring for large values of the cool electron density are only limited by positive potential double layers. Both the lower and upper Mach numbers for the slow electron-acoustic solitons are computed and discussed

  13. Probing hot-electron effects in wide area plasmonic surfaces using X-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ayas, Sencer; Cupallari, Andi; Dana, Aykutlu, E-mail: aykutlu@unam.bilkent.edu.tr [UNAM Institute of Materials Science and Nanotechnology, Bilkent University, 06800 Ankara (Turkey)

    2014-12-01

    Plasmon enhanced hot carrier formation in metallic nanostructures increasingly attracts attention due to potential applications in photodetection, photocatalysis, and solar energy conversion. Here, hot-electron effects in nanoscale metal-insulator-metal (MIM) structures are investigated using a non-contact X-ray photoelectron spectroscopy based technique using continuous wave X-ray and laser excitations. The effects are observed through shifts of the binding energy of the top metal layer upon excitation with lasers of 445, 532, and 650 nm wavelength. The shifts are polarization dependent for plasmonic MIM grating structures fabricated by electron beam lithography. Wide area plasmonic MIM surfaces fabricated using a lithography free route by the dewetting of evaporated Ag on HfO{sub 2} exhibit polarization independent optical absorption and surface photovoltage. Using a simple model and making several assumptions about the magnitude of the photoemission current, the responsivity and external quantum efficiency of wide area plasmonic MIM surfaces are estimated as 500 nA/W and 11 × 10{sup −6} for 445 nm illumination.

  14. Signatures of hot electrons and fluorescence in Mo Kα emission on Z

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, S. B.; Ampleford, D. J.; Cuneo, M. E.; Jones, B.; Jennings, C. A.; Coverdale, C. A.; Rochau, G. A.; Dunham, G. [Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Ouart, N.; Dasgupta, A.; Giuliani, J. L. [Naval Research Laboratory, Washington, DC 20375 (United States); Apruzese, J. P. [Consultant to NRL through Engility Corp., Chantilly, Virginia 20151 (United States)

    2014-03-15

    Recent experiments on the Z accelerator have produced high-energy (17 keV) inner-shell K-alpha emission from molybdenum wire array z-pinches. Extensive absolute power and spectroscopic diagnostics along with collisional-radiative modeling enable detailed investigation into the roles of thermal, hot electron, and fluorescence processes in the production of high-energy x-rays. We show that changing the dimensions of the arrays can impact the proportion of thermal and non-thermal K-shell x-rays.

  15. Low-Noise Wide Bandwith, Hot Electron Bolometer Mixers for Submillimeter Wavelengths

    Science.gov (United States)

    McGrath, W. R.

    1995-01-01

    Recently a novel superconductive hot-electron micro-bolometer has been proposed which is both fast and sensitive (D. E. Prober, Appl. Phys. Lett. 62, 2119, 1993). This device has several important properties which make it useful as a heterodyne sensor for radioastronomy applications at frequencies above 1 THz. The thermal response time of the device is fast enough, several 10's of picoseconds, to allow for IF's of several GHz. This bolometer mixer should operate well up to at least 10 THz. There is no energy gap limitation as in an SIS mixer, since the mixing process relies on heating of the electron gas. In fact, rf power is absorbed more uniformly above the gap frequency. The mixer noise should be near quantum-limited, and the local oscillator (LO) power requirement is very low: / 10 nW for a Nb device. One of the unique features of this device is that it employs rapid electron diffusion into a normal metal, rather than phonon emission, as the thermal conductance that cools the heated electrons. In order for diffusion to dominate over phonon emission, the device must be short, less than 0.5.

  16. Resonant plasmonic terahertz detection in vertical graphene-base hot-electron transistors

    Energy Technology Data Exchange (ETDEWEB)

    Ryzhii, V. [Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Center for Photonics and Infrared Engineering, Bauman Moscow State Technical University and Institute of Ultra High Frequency Semiconductor Electronics of RAS, Moscow 111005 (Russian Federation); Otsuji, T. [Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577 (Japan); Ryzhii, M. [Department of Computer Science and Engineering, University of Aizu, Aizu-Wakamatsu 965-8580 (Japan); Mitin, V. [Department of Electrical Engineering, University at Buffalo, SUNY, Buffalo, New York 1460-1920 (United States); Shur, M. S. [Department of Electrical, Computer, and System Engineering and Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

    2015-11-28

    We analyze dynamic properties of vertical graphene-base hot-electron transistors (GB-HETs) and consider their operation as detectors of terahertz (THz) radiation using the developed device model. The GB-HET model accounts for the tunneling electron injection from the emitter, electron propagation across the barrier layers with the partial capture into the GB, and the self-consistent oscillations of the electric potential and the hole density in the GB (plasma oscillations), as well as the quantum capacitance and the electron transit-time effects. Using the proposed device model, we calculate the responsivity of GB-HETs operating as THz detectors as a function of the signal frequency, applied bias voltages, and the structural parameters. The inclusion of the plasmonic effect leads to the possibility of the GB-HET operation at the frequencies significantly exceeding those limited by the characteristic RC-time. It is found that the responsivity of GB-HETs with a sufficiently perfect GB exhibits sharp resonant maxima in the THz range of frequencies associated with the excitation of plasma oscillations. The positions of these maxima are controlled by the applied bias voltages. The GB-HETs can compete with and even surpass other plasmonic THz detectors.

  17. A model for hot electron phenomena: Theory and general results

    International Nuclear Information System (INIS)

    Carrillo, J.L.; Rodriquez, M.A.

    1988-10-01

    We propose a model for the description of the hot electron phenomena in semiconductors. Based on this model we are able to reproduce accurately the main characteristics observed in experiments of electric field transport, optical absorption, steady state photoluminescence and relaxation process. Our theory does not contain free nor adjustable parameters, it is very fast computerwise, and incorporates the main collision mechanisms including screening and phonon heating effects. Our description on a set of nonlinear rate equations in which the interactions are represented by coupling coefficients or effective frequencies. We calculate three coefficients from the characteristic constants and the band structure of the material. (author). 22 refs, 5 figs, 1 tab

  18. Coulomb explosion of “hot spot”

    Energy Technology Data Exchange (ETDEWEB)

    Oreshkin, V. I., E-mail: oreshkin@ovpe.hcei.tsc.ru [Institute of High Current Electrons, SB, RAS, Tomsk (Russian Federation); Tomsk Polytechnic University, Tomsk (Russian Federation); Oreshkin, E. V. [P. N. Lebedev Physical Institute, RAS, Moscow (Russian Federation); Chaikovsky, S. A. [Institute of High Current Electrons, SB, RAS, Tomsk (Russian Federation); P. N. Lebedev Physical Institute, RAS, Moscow (Russian Federation); Institute of Electrophysics, UD, RAS, Ekaterinburg (Russian Federation); Artyomov, A. P. [Institute of High Current Electrons, SB, RAS, Tomsk (Russian Federation)

    2016-09-15

    The study presented in this paper has shown that the generation of hard x rays and high-energy ions, which are detected in pinch implosion experiments, may be associated with the Coulomb explosion of the hot spot that is formed due to the outflow of the material from the pinch cross point. During the process of material outflow, the temperature of the hot spot plasma increases, and conditions arise for the plasma electrons to become continuously accelerated. The runaway of electrons from the hot spot region results in the buildup of positive space charge in this region followed by a Coulomb explosion. The conditions for the hot spot plasma electrons to become continuously accelerated have been revealed, and the estimates have been obtained for the kinetic energy of the ions generated by the Coulomb explosion.

  19. Coulomb explosion of “hot spot”

    International Nuclear Information System (INIS)

    Oreshkin, V. I.; Oreshkin, E. V.; Chaikovsky, S. A.; Artyomov, A. P.

    2016-01-01

    The study presented in this paper has shown that the generation of hard x rays and high-energy ions, which are detected in pinch implosion experiments, may be associated with the Coulomb explosion of the hot spot that is formed due to the outflow of the material from the pinch cross point. During the process of material outflow, the temperature of the hot spot plasma increases, and conditions arise for the plasma electrons to become continuously accelerated. The runaway of electrons from the hot spot region results in the buildup of positive space charge in this region followed by a Coulomb explosion. The conditions for the hot spot plasma electrons to become continuously accelerated have been revealed, and the estimates have been obtained for the kinetic energy of the ions generated by the Coulomb explosion.

  20. Hot subluminous star: HDE 283048

    International Nuclear Information System (INIS)

    Laget, M.; Vuillemin, A.; Parsons, S.B.; Henize, K.G.; Wray, J.D.

    1978-01-01

    The star HDE 283048, located at α = 3/sup h/50/sup m/.3, delta = +25 0 36', shows a strong ultraviolet continuum. Ground-based observations indicate a hot-dominated composite spectrum. Several lines of evidence suggest that the hot component is a hot subdwarf. 2 figures

  1. On the relaxation of cold electrons and hot ions

    International Nuclear Information System (INIS)

    Potapenko, I.F.; Bobylev, A.V.; Azevedo, C.A. de; Sakanaka, P.H.; Assis, A.S. de

    1998-01-01

    The relaxation process of a space uniform plasma composed of cold electrons and one species of hot ions is studied numerically using one- and two-dimensional Landau - Fokker - Planck codes. Relaxation of a monoenergetic ion beam is considered in possibly extreme temperature regimes. Special attention is paid to the deviation of the relaxation process from the classical picture, which is characterized by the close initial temperatures T e >(m e /m i ) 1/3 T i . The present results give quite a clear idea of the relaxation picture for any initial temperatures also in extreme temperature regimes. A difference scheme, preserving the number of particles and the energy, gives the possibility of solving the problem numerically without error accumulation, except for machine errors. copyright 1998 American Institute of Physics

  2. The development of terahertz superconducting hot-electron bolometric mixers

    International Nuclear Information System (INIS)

    Semenov, Alexei; Richter, Heiko; Smirnov, Konstantin; Voronov, Boris; Gol'tsman, Gregory; Huebers, Heinz-Wilhelm

    2004-01-01

    We present recent advances in the development of NbN hot-electron bolometric (HEB) mixers for flying terahertz heterodyne receivers. Three important issues have been addressed: the quality of the source NbN films, the effect of the bolometer size on the spectral properties of different planar feed antennas, and the local oscillator (LO) power required for optimal operation of the mixer. Studies of the NbN films with an atomic force microscope indicated a surface structure that may affect the performance of the smallest mixers. Measured spectral gain and noise temperature suggest that at frequencies above 2.5 THz the spiral feed provides better overall performance than the double-slot feed. Direct measurements of the optimal LO power support earlier estimates made in the framework of the uniform mixer model

  3. Study of Hot-Electron Effects, Breakdown and Reliability in FETS, HEMTS, and HBT’S

    Science.gov (United States)

    1998-08-01

    device (VDS = 7.5 V, VQS = -0.1 V, 137 hrs). (b) Drain Current FT-DLTS measurements in an as received device (open simbols ) and in a device after hot...electron stress test: VDS = 7.5 V, VQS = - 0.1 V, 137 hrs (closed simbols ). output characteristics of degraded devices and completely eliminates

  4. Evaluation of runaway-electron effects on plasma-facing components for NET

    Science.gov (United States)

    Bolt, H.; Calén, H.

    1991-03-01

    Runaway electrons which are generated during disruptions can cause serious damage to plasma facing components in a next generation device like NET. A study was performed to quantify the response of NET plasma facing components to runaway-electron impact. For the determination of the energy deposition in the component materials Monte Carlo computations were performed. Since the subsurface metal structures can be strongly heated under runaway-electron impact from the computed results damage threshold values for the thermal excursions were derived. These damage thresholds are strongly dependent on the materials selection and the component design. For a carbonmolybdenum divertor with 10 and 20 mm carbon armour thickness and 1 degree electron incidence the damage thresholds are 100 MJ/m 2 and 220 MJ/m 2. The thresholds for a carbon-copper divertor under the same conditions are about 50% lower. On the first wall damage is anticipated for energy depositions above 180 MJ/m 2.

  5. Investigation of the aluminium-aluminium oxide reversible transformation as observed by hot stage electron microscopy.

    Science.gov (United States)

    Grove, C. A.; Judd, G.; Ansell, G. S.

    1972-01-01

    Thin foils of high purity aluminium and an Al-Al2O3 SAP type of alloy were oxidised in a specially designed hot stage specimen chamber in an electron microscope. Below 450 C, amorphous aluminium oxide formed on the foil surface and was first detectable at foil edges, holes, and pits. Islands of aluminium then nucleated in this amorphous oxide. The aluminium islands displayed either a lateral growth with eventual coalescence with other islands, or a reoxidation process which caused the islands to disappear. The aluminium island formation was determined to be related to the presence of the electron beam. A mechanism based upon electron charging due to the electron beam was proposed to explain the nucleation, growth, coalescence, disappearance, and geometry of the aluminium islands.

  6. Elastic scattering by hot electrons and apparent lifetime of longitudinal optical phonons in gallium nitride

    Energy Technology Data Exchange (ETDEWEB)

    Khurgin, Jacob B., E-mail: jakek@jhu.edu [Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States); Bajaj, Sanyam; Rajan, Siddharth [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)

    2015-12-28

    Longitudinal optical (LO) phonons in GaN generated in the channel of high electron mobility transistors (HEMT) are shown to undergo nearly elastic scattering via collisions with hot electrons. The net result of these collisions is the diffusion of LO phonons in the Brillouin zone causing reduction of phonon and electron temperatures. This previously unexplored diffusion mechanism explicates how an increase in electron density causes reduction of the apparent lifetime of LO phonons, obtained from the time resolved Raman studies and microwave noise measurements, while the actual decay rate of the LO phonons remains unaffected by the carrier density. Therefore, the saturation velocity in GaN HEMT steadily declines with increased carrier density, in a qualitative agreement with experimental results.

  7. Effect of energetic electrons on dust charging in hot cathode filament discharge

    Science.gov (United States)

    Kakati, B.; Kausik, S. S.; Saikia, B. K.; Bandyopadhyay, M.

    2011-03-01

    The effect of energetic electrons on dust charging for different types of dust is studied in hydrogen plasma. The hydrogen plasma is produced by hot cathode filament discharge method in a dusty plasma device. A full line cusped magnetic field cage is used to confine the plasma elements. To study the plasma parameters for various discharge conditions, a cylindrical Langmuir probe having 0.15 mm diameter and 10.0 mm length is used. An electronically controlled dust dropper is used to drop the dust particles into the plasma. For different discharge conditions, the dust current is measured using a Faraday cup connected to an electrometer. The effect of secondary emission as well as discharge voltage on charging of dust grains in hydrogen plasma is studied with different dust.

  8. Effect of energetic electrons on dust charging in hot cathode filament discharge

    International Nuclear Information System (INIS)

    Kakati, B.; Kausik, S. S.; Saikia, B. K.; Bandyopadhyay, M.

    2011-01-01

    The effect of energetic electrons on dust charging for different types of dust is studied in hydrogen plasma. The hydrogen plasma is produced by hot cathode filament discharge method in a dusty plasma device. A full line cusped magnetic field cage is used to confine the plasma elements. To study the plasma parameters for various discharge conditions, a cylindrical Langmuir probe having 0.15 mm diameter and 10.0 mm length is used. An electronically controlled dust dropper is used to drop the dust particles into the plasma. For different discharge conditions, the dust current is measured using a Faraday cup connected to an electrometer. The effect of secondary emission as well as discharge voltage on charging of dust grains in hydrogen plasma is studied with different dust.

  9. Proton probe measurement of fast advection of magnetic fields by hot electrons

    International Nuclear Information System (INIS)

    Willingale, L; Thomas, A G R; Nilson, P M; Kaluza, M C; Dangor, A E; Evans, R G; Fernandes, P; Haines, M G; Kamperidis, C; Kingham, R J; Ridgers, C P; Sherlock, M; Wei, M S; Najmudin, Z; Krushelnick, K; Bandyopadhyay, S; Notley, M; Minardi, S; Rozmus, W; Tatarakis, M

    2011-01-01

    A laser generated proton beam was used to measure the megagauss strength self-generated magnetic fields from a nanosecond laser interaction with an aluminum target. At intensities of 10 15 W cm −2 , the significant hot electron production and strong heat fluxes result in non-local transport becoming important to describe the magnetic field dynamics. Two-dimensional implicit Vlasov–Fokker–Planck modeling shows that fast advection of the magnetic field from the focal region occurs via the Nernst effect at significantly higher velocities than the sound speed, v N /c s ≈ 10.

  10. Non-uniform absorption of terahertz radiation on superconducting hot electron bolometer microbridges

    International Nuclear Information System (INIS)

    Miao, W.; Zhang, W.; Zhong, J. Q.; Shi, S. C.; Delorme, Y.; Lefevre, R.; Feret, A.; Vacelet, T.

    2014-01-01

    We interpret the experimental observation of a frequency-dependence of superconducting hot electron bolometer (HEB) mixers by taking into account the non-uniform absorption of the terahertz radiation on the superconducting HEB microbridge. The radiation absorption is assumed to be proportional to the local surface resistance of the HEB microbridge, which is computed using the Mattis-Bardeen theory. With this assumption the dc and mixing characteristics of a superconducting niobium-nitride (NbN) HEB device have been modeled at frequencies below and above the equilibrium gap frequency of the NbN film

  11. Capture dynamics of hot electrons on quantum dots in RTDs studied by noise measurement

    International Nuclear Information System (INIS)

    Hees, S S; Kardynal, B E; Shields, A J; Farrer, I; Ritchie, D A

    2008-01-01

    We investigate the noise in quantum dot resonant tunnelling diodes (QDRTDs), where the quantum dots (QDs) placed in the collector experience electric fields that vary in a wide range. The trapping/detrapping of electrons on the QDs dominated the measured electrical noise. The model that we derived for the noise explains the experimental data well. The QD capture cross-section is one to two orders of magnitude smaller than the physical size of the QDs due to the reduced probability of capturing a hot electron on the QD. The model is a powerful tool to design the noise characteristics of QDRTD single photon-detectors

  12. Modeling and Optimization of a High-Tc Hot-Electron Superconducting Mixer for Terahertz Applicaitons

    Science.gov (United States)

    Karasik, B. S.; McGrath, W. R.; Gaidis, M. C.; Burns, M. J.; Kleinsasser, A. W.; Delin, K. A.; Vasquez, R. P.

    1996-01-01

    The development of a YBa(sub 2)Cu(sub 3)O(sub 7-(kronecker delta))(YBCO) hot-electron bolometer (HEB) quasioptical mixer for a 2.5 heterodyne receiver is discussed. The modeled device is a submicron bridge made from a 10 nm thick film on a high thermal conductance substrate. The mixer performance expected for this device is analyzed in the framework of a two-temperature model which includes heating both of the electrons and the lattice. Also, the contribution of heat diffusion from the film through the substrate and from the film to the normal metal contacts is evaluated....a single sideband temperature of less than 2000k is predicted.

  13. Superconducting Hot-Electron Submillimeter-Wave Detector

    Science.gov (United States)

    Karasik, Boris; McGrath, William; Leduc, Henry

    2009-01-01

    A superconducting hot-electron bolometer has been built and tested as a prototype of high-sensitivity, rapid-response detectors of submillimeter-wavelength radiation. There are diverse potential applications for such detectors, a few examples being submillimeter spectroscopy for scientific research; detection of leaking gases; detection of explosive, chemical, and biological weapons; and medical imaging. This detector is a superconducting-transition- edge device. Like other such devices, it includes a superconducting bridge that has a low heat capacity and is maintained at a critical temperature (T(sub c)) at the lower end of its superconducting-transition temperature range. Incident photons cause transient increases in electron temperature through the superconducting-transition range, thereby yielding measurable increases in electrical resistance. In this case, T(sub c) = 6 K, which is approximately the upper limit of the operating-temperature range of silicon-based bolometers heretofore used routinely in many laboratories. However, whereas the response speed of a typical silicon- based laboratory bolometer is characterized by a frequency of the order of a kilohertz, the response speed of the present device is much higher characterized by a frequency of the order of 100 MHz. For this or any bolometer, a useful figure of merit that one seeks to minimize is (NEP)(tau exp 1/2), where NEP denotes the noise-equivalent power (NEP) and the response time. This figure of merit depends primarily on the heat capacity and, for a given heat capacity, is approximately invariant. As a consequence of this approximate invariance, in designing a device having a given heat capacity to be more sensitive (to have lower NEP), one must accept longer response time (slower response) or, conversely, in designing it to respond faster, one must accept lower sensitivity. Hence, further, in order to increase both the speed of response and the sensitivity, one must make the device very small in

  14. 21 CFR 11.200 - Electronic signature components and controls.

    Science.gov (United States)

    2010-04-01

    ... signature components and controls. (a) Electronic signatures that are not based upon biometrics shall: (1) Employ at least two distinct identification components such as an identification code and password. (i... signatures based upon biometrics shall be designed to ensure that they cannot be used by anyone other than...

  15. Measuring processes with opto-electronic semiconductor components

    International Nuclear Information System (INIS)

    1985-01-01

    This is a report on the state of commercially available semiconductor emitters and detectors for the visible, near, middle and remote infrared range. A survey is given on the distance, speed, flow and length measuring techniques using opto-electronic components. Automatic focussing, the use of light barriers, non-contact temperature measurements, spectroscopic gas, liquid and environmental measurement techniques and gas analysis in medical techniques show further applications of the new components. The modern concept of guided radiation in optical fibres and their use in system technology is briefly explained. (DG) [de

  16. E-commerce within the South African electronic component distribution industry

    OpenAIRE

    2012-01-01

    M.B.A. This dissertation looks at E-Commerce in the South African electronic component distribution industry. With this in mind, various questions were defined and these were used to help understand the current situation, determine the future that ECommerce should have in the industry and find a mechanism to go from the current to the future situation, the questions are as follows: Has the traditional electronic component distribution channel been made obsolete by E-Commerce? What does the...

  17. Femtosecond-laser induced dynamics of CO on Ru(0001): Deep insights from a hot-electron friction model including surface motion

    Science.gov (United States)

    Scholz, Robert; Floß, Gereon; Saalfrank, Peter; Füchsel, Gernot; Lončarić, Ivor; Juaristi, J. I.

    2016-10-01

    A Langevin model accounting for all six molecular degrees of freedom is applied to femtosecond-laser induced, hot-electron driven dynamics of Ru(0001)(2 ×2 ):CO. In our molecular dynamics with electronic friction approach, a recently developed potential energy surface based on gradient-corrected density functional theory accounting for van der Waals interactions is adopted. Electronic friction due to the coupling of molecular degrees of freedom to electron-hole pairs in the metal are included via a local density friction approximation, and surface phonons by a generalized Langevin oscillator model. The action of ultrashort laser pulses enters through a substrate-mediated, hot-electron mechanism via a time-dependent electronic temperature (derived from a two-temperature model), causing random forces acting on the molecule. The model is applied to laser induced lateral diffusion of CO on the surface, "hot adsorbate" formation, and laser induced desorption. Reaction probabilities are strongly enhanced compared to purely thermal processes, both for diffusion and desorption. Reaction yields depend in a characteristic (nonlinear) fashion on the applied laser fluence, as well as branching ratios for various reaction channels. Computed two-pulse correlation traces for desorption and other indicators suggest that aside from electron-hole pairs, phonons play a non-negligible role for laser induced dynamics in this system, acting on a surprisingly short time scale. Our simulations on precomputed potentials allow for good statistics and the treatment of long-time dynamics (300 ps), giving insight into this system which hitherto has not been reached. We find generally good agreement with experimental data where available and make predictions in addition. A recently proposed laser induced population of physisorbed precursor states could not be observed with the present low-coverage model.

  18. Critical density for Landau damping in a two-electron-component plasma

    Energy Technology Data Exchange (ETDEWEB)

    Rupp, Constantin F.; López, Rodrigo A.; Araneda, Jaime A. [Departamento de Física, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Concepción (Chile)

    2015-10-15

    The asymptotic evolution of an initial perturbation in a collisionless two-electron-component plasma with different temperatures is studied numerically. The transition between linear and nonlinear damping regimes is determined by slowly varying the density of the secondary electron-component using high-resolution Vlasov-Poisson simulations. It is shown that, for fixed amplitude perturbations, this transition behaves as a critical phenomenon with time scales and field amplitudes exhibiting power-law dependencies on the threshold density, similar to the critical amplitude behavior in a single-component plasma.

  19. Influence of lateral target size on hot electron production and electromagnetic pulse emission from laser-irradiated metallic targets

    International Nuclear Information System (INIS)

    Chen Ziyu; Li Jianfeng; Yu Yong; Li Xiaoya; Peng Qixian; Zhu Wenjun; Wang Jiaxiang

    2012-01-01

    The influences of lateral target size on hot electron production and electromagnetic pulse emission from laser interaction with metallic targets have been investigated. Particle-in-cell simulations at high laser intensities show that the yield of hot electrons tends to increase with lateral target size, because the larger surface area reduces the electrostatic field on the target, owing to its expansion along the target surface. At lower laser intensities and longer time scales, experimental data characterizing electromagnetic pulse emission as a function of lateral target size also show target-size effects. Charge separation and a larger target tending to have a lower target potential have both been observed. The increase in radiation strength and downshift in radiation frequency with increasing lateral target size can be interpreted using a simple model of the electrical capacity of the target.

  20. Influence of lateral target size on hot electron production and electromagnetic pulse emission from laser-irradiated metallic targets

    Energy Technology Data Exchange (ETDEWEB)

    Chen Ziyu; Li Jianfeng; Yu Yong; Li Xiaoya; Peng Qixian; Zhu Wenjun [National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang, Sichuan 621900 (China); Wang Jiaxiang [State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062 (China)

    2012-11-15

    The influences of lateral target size on hot electron production and electromagnetic pulse emission from laser interaction with metallic targets have been investigated. Particle-in-cell simulations at high laser intensities show that the yield of hot electrons tends to increase with lateral target size, because the larger surface area reduces the electrostatic field on the target, owing to its expansion along the target surface. At lower laser intensities and longer time scales, experimental data characterizing electromagnetic pulse emission as a function of lateral target size also show target-size effects. Charge separation and a larger target tending to have a lower target potential have both been observed. The increase in radiation strength and downshift in radiation frequency with increasing lateral target size can be interpreted using a simple model of the electrical capacity of the target.

  1. Two-photon-induced hot-electron transfer to a single molecule in a scanning tunneling microscope

    International Nuclear Information System (INIS)

    Wu, S. W.; Ho, W.

    2010-01-01

    The junction of a scanning tunneling microscope (STM) operating in the tunneling regime was irradiated with femtosecond laser pulses. A photoexcited hot electron in the STM tip resonantly tunnels into an excited state of a single molecule on the surface, converting it from the neutral to the anion. The electron-transfer rate depends quadratically on the incident laser power, suggesting a two-photon excitation process. This nonlinear optical process is further confirmed by the polarization measurement. Spatial dependence of the electron-transfer rate exhibits atomic-scale variations. A two-pulse correlation experiment reveals the ultrafast dynamic nature of photoinduced charging process in the STM junction. Results from these experiments are important for understanding photoinduced interfacial charge transfer in many nanoscale inorganic-organic structures.

  2. Electric vehicle recycling 2020: Key component power electronics.

    Science.gov (United States)

    Bulach, Winfried; Schüler, Doris; Sellin, Guido; Elwert, Tobias; Schmid, Dieter; Goldmann, Daniel; Buchert, Matthias; Kammer, Ulrich

    2018-04-01

    Electromobility will play a key role in order to reach the specified ambitious greenhouse gas reduction targets in the German transport sector of 42% between 1990 and 2030. Subsequently, a significant rise in the sale of electric vehicles (EVs) is to be anticipated in future. The amount of EVs to be recycled will rise correspondingly after a delay. This includes the recyclable power electronics modules which are incorporated in every EV as an important component for energy management. Current recycling methods using car shredders and subsequent post shredder technologies show high recycling rates for the bulk metals but are still associated with high losses of precious and strategic metals such as gold, silver, platinum, palladium and tantalum. For this reason, the project 'Electric vehicle recycling 2020 - key component power electronics' developed an optimised recycling route for recycling power electronics modules from EVs which is also practicable in series production and can be implemented using standardised technology. This 'WEEE recycling route' involves the disassembly of the power electronics from the vehicle and a subsequent recycling in an electronic end-of-life equipment recycling plant. The developed recycling process is economical under the current conditions and raw material prices, even though it involves considerably higher costs than recycling using the car shredder. The life cycle assessment shows basically good results, both for the traditional car shredder route and the developed WEEE recycling route: the latter provides additional benefits from some higher recovery rates and corresponding credits.

  3. Reliability prediction system based on the failure rate model for electronic components

    International Nuclear Information System (INIS)

    Lee, Seung Woo; Lee, Hwa Ki

    2008-01-01

    Although many methodologies for predicting the reliability of electronic components have been developed, their reliability might be subjective according to a particular set of circumstances, and therefore it is not easy to quantify their reliability. Among the reliability prediction methods are the statistical analysis based method, the similarity analysis method based on an external failure rate database, and the method based on the physics-of-failure model. In this study, we developed a system by which the reliability of electronic components can be predicted by creating a system for the statistical analysis method of predicting reliability most easily. The failure rate models that were applied are MILHDBK- 217F N2, PRISM, and Telcordia (Bellcore), and these were compared with the general purpose system in order to validate the effectiveness of the developed system. Being able to predict the reliability of electronic components from the stage of design, the system that we have developed is expected to contribute to enhancing the reliability of electronic components

  4. Modification of a scanning electron microscope for remote operation in a hot cell

    International Nuclear Information System (INIS)

    Reed, J.R.; Watson, H.E.; Smidt, F.A. Jr.

    1982-01-01

    Scanning electron microscopy (SEM) examination of broken fracture specimens is an essential part of the characterization of the failure mode of fracture toughness of specimens. The large specimen mass required for such examinations dictates the use of a shielded facility for performing such examinations on irradiated specimens. This report describes the modification of a commercial SEM for remote operation in a hot cell. The facility is used to examine specimens from several Navy and DOE-sponsored programs conducted at NRL which require the examination of radioactive materials

  5. On the OSL curve shape and preheat treatment of electronic components from portable electronic devices

    DEFF Research Database (Denmark)

    Woda, Clemens; Greilich, Steffen; Beerten, Koen

    2010-01-01

    The shape of the OSL decay curve and the effect of longer time delays between accidental exposure and readout of alumina-rich electronic components from portable electronic devices are investigated. The OSL decay curve follows a hyperbolic decay function, which is interpreted as an approximation ...

  6. Laser generated hot electron transport in an externally applied magnetic field

    International Nuclear Information System (INIS)

    Burnett, N.H.; Enright, G.D.

    1986-01-01

    The authors have investigated the effect of an externally applied DC magnetic field on the generation and transport of hot electrons in CO/sub 2/ laser irradiation of cylindrical targets. The targets used in these studies were 6.3 mm diameter metal rods through which a pulsed current was driven from an external capacitor. Magnetic fields up to 150 kgauss were produced at the target surface. The CO/sub 2/ laser was focused with an f/5 lens resulting in a laser intensity of ≅3 x 10/sup 14/ W/cm/sup 2/ in a 100 μm diameter focal spot. The effect of the external magnetic field on the generation and inward transport of superhot (≥ 100 keV) electrons was studied. Principal diagnostics included a six channel hard x-ray spectrometer, a high energy x-ray pinhole camera, a LiF Laue x-ray spectrograph and a Ross-filtered (W-Ta) pair of x-ray detectors. The latter two diagnostics were designed to detect Au Kα /sub emission at 68.2 keV

  7. A review of typical thermal fatigue failure models for solder joints of electronic components

    Science.gov (United States)

    Li, Xiaoyan; Sun, Ruifeng; Wang, Yongdong

    2017-09-01

    For electronic components, cyclic plastic strain makes it easier to accumulate fatigue damage than elastic strain. When the solder joints undertake thermal expansion or cold contraction, different thermal strain of the electronic component and its corresponding substrate is caused by the different coefficient of thermal expansion of the electronic component and its corresponding substrate, leading to the phenomenon of stress concentration. So repeatedly, cracks began to sprout and gradually extend [1]. In this paper, the typical thermal fatigue failure models of solder joints of electronic components are classified and the methods of obtaining the parameters in the model are summarized based on domestic and foreign literature research.

  8. ON THE NATURE OF THE HOT COMPONENT IN THE SYMBIOTIC, SUPERSOFT X-RAY BINARY AG DRACONIS

    Energy Technology Data Exchange (ETDEWEB)

    Sion, Edward M.; Moreno, Jackeline; Godon, Patrick [Astronomy and Astrophysics, Villanova University, 800 Lancaster Avenue, Villanova, PA 19085 (United States); Sabra, Bassem [Department of Physics and Astronomy, Notre Dame University-Louaize, Zouk Mosbeh (Lebanon); Mikolajewska, Joanna, E-mail: edward.sion@villanova.edu, E-mail: jackeline.moreno@villanova.edu, E-mail: patrick.godon@villanova.edu, E-mail: bsabra@ndu.edu.lb, E-mail: mikolaj@camk.edu.pl [Copernicus Astronomical Center, Warsaw (Poland)

    2012-12-01

    AG Dra is a symbiotic variable consisting of a metal-poor, yellow giant mass donor underfilling its Roche lobe and a hot accreting white dwarf, possibly surrounded by an optically thick, bright accretion disk (which could be present from wind accretion). We constructed NLTE synthetic spectral models for white dwarf spectra and optically thick accretion disk spectra to model a FUSE spectrum of AG Dra, obtained when the hot component is viewed in front of the yellow giant. The spectrum has been dereddened (E(B - V) = 0.05) and the model fitting carried out, with the distance regarded as a free parameter but required to be larger than the Hipparcos lower limit of 1 kpc. We find that the best-fitting model is a bare accreting white dwarf with M{sub wd} = 0.4 M{sub Sun }, T{sub eff} = 80,000 K, and a model-derived distance of 1543 pc. Higher temperatures are ruled out due to excess flux at the shortest wavelengths while a lower temperature decreases the distance below 1 kpc. Any accretion disk that might be present is only a minor contributor to the far-UV flux. This raises the possibility that the soft X-rays originate from a very hot boundary layer between a putative accretion disk and the accreting star.

  9. Principal component analysis for neural electron/jet discrimination in highly segmented calorimeters

    International Nuclear Information System (INIS)

    Vassali, M.R.; Seixas, J.M.

    2001-01-01

    A neural electron/jet discriminator based on calorimetry is developed for the second-level trigger system of the ATLAS detector. As preprocessing of the calorimeter information, a principal component analysis is performed on each segment of the two sections (electromagnetic and hadronic) of the calorimeter system, in order to reduce significantly the dimension of the input data space and fully explore the detailed energy deposition profile, which is provided by the highly-segmented calorimeter system. It is shown that projecting calorimeter data onto 33 segmented principal components, the discrimination efficiency of the neural classifier reaches 98.9% for electrons (with only 1% of false alarm probability). Furthermore, restricting data projection onto only 9 components, an electron efficiency of 99.1% is achieved (with 3% of false alarm), which confirms that a fast triggering system may be designed using few components

  10. Establishment of design space for high current gain in III-N hot electron transistors

    Science.gov (United States)

    Gupta, Geetak; Ahmadi, Elaheh; Suntrup, Donald J., III; Mishra, Umesh K.

    2018-01-01

    This paper establishes the design space of III-N hot electron transistors (HETs) for high current gain by designing and fabricating HETs with scaled base thickness. The device structure consists of GaN-based emitter, base and collector regions where emitter and collector barriers are implemented using AlN and InGaN layers, respectively, as polarization-dipoles. Electrons tunnel through the AlN layer to be injected into the base at a high energy where they travel in a quasi-ballistic manner before being collected. Current gain increases from 1 to 3.5 when base thickness is reduced from 7 to 4 nm. The extracted mean free path (λ mfp) is 5.8 nm at estimated injection energy of 1.5 eV.

  11. Contaminated Metal Components in Dismantling by Hot Cutting Processes

    International Nuclear Information System (INIS)

    Cesari, Franco G.; Conforti, Gianmario; Rogante, Massimo; Giostri, Angelo

    2006-01-01

    During the preparatory dismantling activities of Caorso's Nuclear Power Plant (NPP), an experimental campaign using plasma and oxyacetylene metal cutting processes has been performed and applied to plates and tubes exposed to the coolant steam of the reactor. The plant (Boiling Water Reactor, 870 MWe) was designed and built in the 70's, and it was fully operating by 1981 to 1986 being shut down after 1987 Italy's poll that abrogated nuclear power based on U235 fission. The campaign concerns no activated materials, even if the analyses have been performed of by use contaminated components under the free release level, not yet taking into account radioactivity. In this paper, the parameters related to inhalable aerosol, solid and volatile residuals production have been, studied during hot processes which applies the same characteristics of the cutting in field for the dismantling programs of Caorso NPP. The technical parameters such as cutting time and cutting rate vs. pipe diameter/thickness/schedule or plate thickness for ferritic alloys and the emissions composition coming from the sectioning are also reported. The results underline the sort of trouble that can emerge in the cutting processes, in particular focusing on the effects comparison between the two cutting processes and the chemical composition of powders captured by filtering the gaseous emission. Some preliminary considerations on methodology to be used during the dismantling have been presented. (authors)

  12. Influence of Bernstein modes on the efficiency of electron cyclotron resonance x-ray source

    International Nuclear Information System (INIS)

    Andreev, V. V.; Nikitin, G.V.; Savanovich, V.Yu.; Umnov, A.M.; Elizarov, L.I.; Serebrennikov, K.S.; Vostrikova, E.A.

    2006-01-01

    The article considers the factors influencing the temperature of hot electron component in an electron cyclotron resonance (ECR) x-ray source. In such sources the electron heating occurs often due to extraordinary electromagnetic wave propagating perpendicularly to the magnetic field. In this case the possibility of the absorption of Bernstein modes is regarded as an additional mechanism of electron heating. The Bernstein modes in an ECR x-ray source can arise due to either linear transformation or parametric instability of external transversal wave. The article briefly reviews also the further experiments which will be carried out to study the influence of Bernstein modes on the increase of hot electron temperature and consequently of x-ray emission

  13. Processes for coating or sealing electronic components with synthetic varnishes

    International Nuclear Information System (INIS)

    Farrugia, M.; Allard, M.

    1981-01-01

    A method of coating or sealing electrical or electronic components with a synthetic resin composition is described which consists of moving each component along a fixed path through a coating station at which at least one surface of the component receives a coating of synthetic resin and then moving each component through a beam of ionising radiation (ultra-violet or beta radiation) for a sufficient time to induce polymerisation of the resin. Suitable resin compositions for the process are listed. (U.K.)

  14. Ion- and electron-acoustic solitons in two-electron temperature space plasmas

    International Nuclear Information System (INIS)

    Lakhina, G. S.; Kakad, A. P.; Singh, S. V.; Verheest, F.

    2008-01-01

    Properties of ion- and electron-acoustic solitons are investigated in an unmagnetized multicomponent plasma system consisting of cold and hot electrons and hot ions using the Sagdeev pseudopotential technique. The analysis is based on fluid equations and the Poisson equation. Solitary wave solutions are found when the Mach numbers exceed some critical values. The critical Mach numbers for the ion-acoustic solitons are found to be smaller than those for electron-acoustic solitons for a given set of plasma parameters. The critical Mach numbers of ion-acoustic solitons increase with the increase of hot electron temperature and the decrease of cold electron density. On the other hand, the critical Mach numbers of electron-acoustic solitons increase with the increase of the cold electron density as well as the hot electron temperature. The ion-acoustic solitons have positive potentials for the parameters considered. However, the electron-acoustic solitons have positive or negative potentials depending whether the fractional cold electron density with respect to the ion density is greater or less than a certain critical value. Further, the amplitudes of both the ion- and electron-acoustic solitons increase with the increase of the hot electron temperature. Possible application of this model to electrostatic solitary waves observed on the auroral field lines by the Viking spacecraft is discussed

  15. Virtual enterprise model for the electronic components business in the Nuclear Weapons Complex

    Energy Technology Data Exchange (ETDEWEB)

    Ferguson, T.J.; Long, K.S.; Sayre, J.A. [Sandia National Labs., Albuquerque, NM (United States); Hull, A.L. [Sandia National Labs., Livermore, CA (United States); Carey, D.A.; Sim, J.R.; Smith, M.G. [Allied-Signal Aerospace Co., Kansas City, MO (United States). Kansas City Div.

    1994-08-01

    The electronic components business within the Nuclear Weapons Complex spans organizational and Department of Energy contractor boundaries. An assessment of the current processes indicates a need for fundamentally changing the way electronic components are developed, procured, and manufactured. A model is provided based on a virtual enterprise that recognizes distinctive competencies within the Nuclear Weapons Complex and at the vendors. The model incorporates changes that reduce component delivery cycle time and improve cost effectiveness while delivering components of the appropriate quality.

  16. Numerical method for the dispersion relation of a hot and inhomogeneous plasma with an electron beam

    International Nuclear Information System (INIS)

    Devia, A.; Orrego, C.E.; Buitrago, G.

    1990-01-01

    A numerical method that is based in kinetic theory (Vlasov-Poison equations) was developed in order to calculate the dispersion relation for the interaction between a hot cylindrical and electron beam in any temperature and density. The plasma-beam system is located in a strong magnetic field. Many examples showing the effect of the temperatures and densities on the dispersion relation are given. (Author)

  17. Self-consistent average-atom scheme for electronic structure of hot and dense plasmas of mixture

    International Nuclear Information System (INIS)

    Yuan Jianmin

    2002-01-01

    An average-atom model is proposed to treat the electronic structures of hot and dense plasmas of mixture. It is assumed that the electron density consists of two parts. The first one is a uniform distribution with a constant value, which is equal to the electron density at the boundaries between the atoms. The second one is the total electron density minus the first constant distribution. The volume of each kind of atom is proportional to the sum of the charges of the second electron part and of the nucleus within each atomic sphere. By this way, one can make sure that electrical neutrality is satisfied within each atomic sphere. Because the integration of the electron charge within each atom needs the size of that atom in advance, the calculation is carried out in a usual self-consistent way. The occupation numbers of electron on the orbitals of each kind of atom are determined by the Fermi-Dirac distribution with the same chemical potential for all kinds of atoms. The wave functions and the orbital energies are calculated with the Dirac-Slater equations. As examples, the electronic structures of the mixture of Au and Cd, water (H 2 O), and CO 2 at a few temperatures and densities are presented

  18. Self-consistent average-atom scheme for electronic structure of hot and dense plasmas of mixture.

    Science.gov (United States)

    Yuan, Jianmin

    2002-10-01

    An average-atom model is proposed to treat the electronic structures of hot and dense plasmas of mixture. It is assumed that the electron density consists of two parts. The first one is a uniform distribution with a constant value, which is equal to the electron density at the boundaries between the atoms. The second one is the total electron density minus the first constant distribution. The volume of each kind of atom is proportional to the sum of the charges of the second electron part and of the nucleus within each atomic sphere. By this way, one can make sure that electrical neutrality is satisfied within each atomic sphere. Because the integration of the electron charge within each atom needs the size of that atom in advance, the calculation is carried out in a usual self-consistent way. The occupation numbers of electron on the orbitals of each kind of atom are determined by the Fermi-Dirac distribution with the same chemical potential for all kinds of atoms. The wave functions and the orbital energies are calculated with the Dirac-Slater equations. As examples, the electronic structures of the mixture of Au and Cd, water (H2O), and CO2 at a few temperatures and densities are presented.

  19. Microstructural analysis of hot press formed 22MnB5 steel

    Science.gov (United States)

    Aziz, Nuraini; Aqida, Syarifah Nur; Ismail, Izwan

    2017-10-01

    This paper presents a microstructural study on hot press formed 22MnB5 steel for enhanced mechanical properties. Hot press forming process consists of simultaneous forming and quenching of heated blank. The 22MnB5 steel was processed at three different parameter settings: quenching time, water temperature and water flow rate. 22MnB5 was processed using 33 full factorial design of experiment (DOE). The full factorial DOE was designed using three factors of quenching time, water temperature and water flow rate at three levels. The factors level were quenching time range of 5 - 11 s, water temperature; 5 - 27°C and water flow rate; 20 - 40 L/min. The as-received and hot press forming processed steel was characterised for metallographic study and martensitic structure area percentage using JEOL Field Emission Scanning Electron Microscopic (FESEM). From the experimental finding, the hot press formed 22MnB5 steel consisted of 50 to 84% martensitic structure area. The minimum quenching time of 8 seconds was required to obtain formed sample with high percentage of martensite. These findings contribute to initial design of processing parameters in hot press forming of 22MnB5 steel blanks for automotive component.

  20. Analysis of recrystallization behavior of hot-deformed austenite reconstructed from electron backscattering diffraction orientation maps of lath martensite

    International Nuclear Information System (INIS)

    Kubota, Manabu; Ushioda, Kohsaku; Miyamoto, Goro; Furuhara, Tadashi

    2016-01-01

    The recrystallization behavior of hot-deformed austenite of a 0.55% C steel at 800 °C was investigated by a method of reconstructing the parent austenite orientation map from an electron backscattering diffraction orientation map of lath martensite. Recrystallized austenite grains were clearly distinguished from un-recrystallized austenite grains. Very good correlation was confirmed between the static recrystallization behavior investigated mechanically by double-hit compression tests and the change in austenite microstructure evaluated by the reconstruction method. The recrystallization behavior of hot-deformed 0.55% C steel at 800 °C is directly revealed and it was observed that by addition of 0.1% V the recrystallization was significantly retarded.

  1. Mechanism of hot spots formation in magnetic Z-pinch

    Energy Technology Data Exchange (ETDEWEB)

    Kubes, P; Kravarik, J [Ceske Vysoke Uceni Technicke, Prague (Czech Republic). Fakulta Elektrotechnicka; Kolacek, K; Krejci, A [Akademie Ved Ceske Republiky, Prague (Czech Republic). Ustav Fyziky Plazmatu; Paduch, M; Tomaszewski, K [Inst. of Plasma Physics and Laser Microfusion, Warsaw (Poland)

    1997-12-31

    The evolution of neon implosion of low energy discharge (4 kJ, 40 kV, 150 kA, 1.1 {mu}s) was studied using X-ray, schlieren and high speed electrooptical visible gated Quadro camera diagnostics. The geometry, the helical structure of pinched column, two steps of pinching and X-ray emission were studied. The diameters, electron density and temperature of the hot spots were determined. The hypothesis of axial component of magnetic field generation, of helical shape of magnetic and electric field lines, of the possibility of the release of magnetic energy and of the acceleration of the keV electrons and ions due to voltage induction during the second pinching of the column are discussed. (author). 3 figs., 5 refs.

  2. Hot Gas Halos in Galaxies

    Science.gov (United States)

    Mulchaey, John

    Most galaxy formation models predict that massive low-redshift disk galaxies are embedded in extended hot halos of externally accreted gas. Such gas appears necessary to maintain ongoing star formation in isolated spirals like the Milky Way. To explain the large population of red galaxies in rich groups and clusters, most galaxy evolution models assume that these hot gas halos are stripped completely when a galaxy enters a denser environment. This simple model has been remarkably successful at reproducing many observed properties of galaxies. Although theoretical arguments suggest hot gas halos are an important component in galaxies, we know very little about this gas from an observational standpoint. In fact, previous observations have failed to detect soft X-ray emission from such halos in disk galaxies. Furthermore, the assumption that hot gas halos are stripped completely when a galaxy enters a group or cluster has not been verified. We propose to combine proprietary and archival XMM-Newton observations of galaxies in the field, groups and clusters to study how hot gas halos are impacted by environment. Our proposed program has three components: 1) The deepest search to date for a hot gas halo in a quiescent spiral galaxy. A detection will confirm a basic tenet of disk galaxy formation models, whereas a non-detection will seriously challenge these models and impose new constraints on the growth mode and feedback history of disk galaxies. 2) A detailed study of the hot gas halos properties of field early-type galaxies. As environmental processes such as stripping are not expected to be important in the field, a study of hot gas halos in this environment will allow us to better understand how feedback and other internal processes impact hot gas halos. 3) A study of hot gas halos in the outskirts of groups and clusters. By comparing observations with our suite of simulations we can begin to understand what role the stripping of hot gas halos plays in galaxy

  3. Hard x-ray (>100 keV) imager to measure hot electron preheat for indirectly driven capsule implosions on the NIF.

    Science.gov (United States)

    Döppner, T; Dewald, E L; Divol, L; Thomas, C A; Burns, S; Celliers, P M; Izumi, N; Kline, J L; LaCaille, G; McNaney, J M; Prasad, R R; Robey, H F; Glenzer, S H; Landen, O L

    2012-10-01

    We have fielded a hard x-ray (>100 keV) imager with high aspect ratio pinholes to measure the spatially resolved bremsstrahlung emission from energetic electrons slowing in a plastic ablator shell during indirectly driven implosions at the National Ignition Facility. These electrons are generated in laser plasma interactions and are a source of preheat to the deuterium-tritium fuel. First measurements show that hot electron preheat does not limit obtaining the fuel areal densities required for ignition and burn.

  4. System for Cooling of Electronic Components

    Science.gov (United States)

    Vasil'ev, L. L.; Grakovich, L. P.; Dragun, L. A.; Zhuravlev, A. S.; Olekhnovich, V. A.; Rabetskii, M. I.

    2017-01-01

    Results of computational and experimental investigations of heat pipes having a predetermined thermal resistance and a system based on these pipes for air cooling of electronic components and diode assemblies of lasers are presented. An efficient compact cooling system comprising heat pipes with an evaporator having a capillary coating of a caked copper powder and a condenser having a developed outer finning, has been deviced. This system makes it possible to remove, to the ambient air, a heat flow of power more than 300 W at a temperature of 40-50°C.

  5. Hot Carrier Generation and Extraction of Plasmonic Alloy Nanoparticles.

    Science.gov (United States)

    Valenti, Marco; Venugopal, Anirudh; Tordera, Daniel; Jonsson, Magnus P; Biskos, George; Schmidt-Ott, Andreas; Smith, Wilson A

    2017-05-17

    The conversion of light to electrical and chemical energy has the potential to provide meaningful advances to many aspects of daily life, including the production of energy, water purification, and optical sensing. Recently, plasmonic nanoparticles (PNPs) have been increasingly used in artificial photosynthesis (e.g., water splitting) devices in order to extend the visible light utilization of semiconductors to light energies below their band gap. These nanoparticles absorb light and produce hot electrons and holes that can drive artificial photosynthesis reactions. For n-type semiconductor photoanodes decorated with PNPs, hot charge carriers are separated by a process called hot electron injection (HEI), where hot electrons with sufficient energy are transferred to the conduction band of the semiconductor. An important parameter that affects the HEI efficiency is the nanoparticle composition, since the hot electron energy is sensitive to the electronic band structure of the metal. Alloy PNPs are of particular importance for semiconductor/PNPs composites, because by changing the alloy composition their absorption spectra can be tuned to accurately extend the light absorption of the semiconductor. This work experimentally compares the HEI efficiency from Ag, Au, and Ag/Au alloy nanoparticles to TiO 2 photoanodes for the photoproduction of hydrogen. Alloy PNPs not only exhibit tunable absorption but can also improve the stability and electronic and catalytic properties of the pure metal PNPs. In this work, we find that the Ag/Au alloy PNPs extend the stability of Ag in water to larger applied potentials while, at the same time, increasing the interband threshold energy of Au. This increasing of the interband energy of Au suppresses the visible-light-induced interband excitations, favoring intraband excitations that result in higher hot electron energies and HEI efficiencies.

  6. Hot-electron plasma formation and confinement in the tandem mirror experiment-upgrade

    International Nuclear Information System (INIS)

    Ress, D.B.

    1988-06-01

    The tandem mirror experiment-upgrade (TMX-U) at the Lawrence Livermore National Laboratory (LLNL) is the first experiment to investigate the thermal-barrier tandem-mirror concept. One attractive feature of the tandem magnetic mirror as a commercial power reactor is that the fusion reactions occur in an easily accessible center-cell. On the other hand, complicated end-cells are necessary to provide magnetohydrodynamic (MHD) stability and improved particle confinement of the center-cell plasma. In these end-cells, enhanced confinement is achieved with a particular axial potential profile that is formed with electron-cyclotron range-of-frequency heating (ECRF heating, ECRH). By modifying the loss rates of electrons at spatially distinct locations within the end-cells, the ECRH can tailor the plasma potential profile in the desired fashion. Specifically, the thermal-barrier concept requires generation of a population of energetic electrons near the midplane of each end-cell. To be effective, the transverse (to the magnetic field) spatial structure of the hot-electron plasma must be fairly uniform. In this dissertation we characterize the spatial structure of the ECRH-generated plasma, and determine how the structure builds up in time. Furthermore, the plasma should efficiently absorb the ECRF power, and a large fraction of the electrons must be well confined near the end-cell midplane. Therefore, we also examine in detail the ECRH power balance, determining how the ECRF power is absorbed by the plasma, and the processes through which that power is confined and lost. 43 refs., 69 figs., 6 tabs

  7. Hot corrosion of pack cementation aluminized carbon steel

    International Nuclear Information System (INIS)

    Waheed, A.F.; Mohamed, K.E.; Abd El-Azim, M.E.; Soliman, H.M.

    1998-01-01

    Low carbon steel was aluminized by the pack cementation technique at various aluminizing temperatures and times in or der to have different aluminide coatings. The aluminized specimens were sprayed at the beginning of the hot corrosion experiments with Na C 1+Na 2 SO 4 solution. The hot corrosion tests were carried out by thermal cycling at 850 degree C in air. The results were evaluated by, corrosion kinetics based on weight change measurements, scanning electron microscopy and energy dispersive X-ray analysis. It was found that the maximum corrosion resistance to this corrosive environment is achieved by aluminizing at 900 degree C for 19 h or 950 degree C for >4 h. These aliminizing conditions lead to formation of thick aluminide coatings with sufficient aluminium concentration (>15 wt%) at their outer surface necessary for continuous formation of protective Al 2 O 3 scale. The tested materials are used in protection of some components used in electric power stations (conventional or nuclear)

  8. Design and construction of electronic components for a ''Novillo'' Tokamak

    International Nuclear Information System (INIS)

    Lopez C, R.

    1986-07-01

    The goal of this effort was to design, construct and make functional the electronic components for a ''Novillo'' Tokamak currently being experimentally investigated at the National Institute of Nuclear Research in Mexico. The problem was to develop programmable electronic switches capable of discharging high voltage kilowatt energies stored in capacitator banks onto the coils of the Tokamak. (author)

  9. Cooled electronic system with liquid-cooled cold plate and thermal spreader coupled to electronic component

    Science.gov (United States)

    Chainer, Timothy J.; Graybill, David P.; Iyengar, Madhusudan K.; Kamath, Vinod; Kochuparambil, Bejoy J.; Schmidt, Roger R.; Steinke, Mark E.

    2018-03-27

    Apparatus and method are provided for facilitating cooling of an electronic component. The apparatus includes a liquid-cooled cold plate and a thermal spreader associated with the cold plate. The cold plate includes multiple coolant-carrying channel sections extending within the cold plate, and a thermal conduction surface with a larger surface area than a surface area of the component to be cooled. The thermal spreader includes one or more heat pipes including multiple heat pipe sections. One or more heat pipe sections are partially aligned to a first region of the cold plate, that is, where aligned to the surface to be cooled, and partially aligned to a second region of the cold plate, which is outside the first region. The one or more heat pipes facilitate distribution of heat from the electronic component to coolant-carrying channel sections of the cold plate located in the second region of the cold plate.

  10. Measuring hot flash phenomenonology using ambulatory prospective digital diaries

    Science.gov (United States)

    Fisher, William I.; Thurston, Rebecca C.

    2016-01-01

    Objective This study provides the description, protocol, and results from a novel prospective ambulatory digital hot flash phenomenon diary. Methods This study included 152 midlife women with daily hot flashes who completed an ambulatory electronic hot flash diary continuously for the waking hours of 3 consecutive days. In this diary, women recorded their hot flashes and accompanying characteristics and associations as the hot flashes occurred. Results Self-reported hot flash severity on the digital diaries indicated that the majority of hot flashes were rated as mild (41.3%) or moderate (43.7%). Severe (13.1%) and very severe (1.8%) hot flashes were less common. Hot flash bother ratings were rated as mild (43%), or moderate (33.5%), with fewer hot flashes reported bothersome (17.5%) or very bothersome (6%). The majority of hot flashes were reported as occurring on the on the face (78.9%), neck (74.7%), and chest (61.3%). Prickly skin was reported concurrently with 32% of hot flashes, 7% with anxiety and 5% with nausea. A novel finding, 38% of hot flashes were accompanied by a premonitory aura. Conclusion A prospective electronic digital hot flash diary allows for a more precise quantitation of hot flashes while overcoming many of the limitations of commonly employed retrospective questionnaires and paper diaries. Unique insights into the phenomenology, loci and associated characteristics of hot flashes were obtained using this device. The digital hot flash phenomenology diary is recommended for future ambulatory studies of hot flashes as a prospective measure of the hot flash experience. PMID:27404030

  11. Electron cloud simulation of the ECR plasma

    International Nuclear Information System (INIS)

    Racz, R.; Biri, S.; Palinkas, J.

    2011-01-01

    Complete text of publication follows. The plasma of the Electron Cyclotron Resonance Ion Source (ECRIS) of ATOMKI is being continuously investigated by different diagnostic methods: using small-sized probes or taking X-ray and visible light photographs. In 2011 three articles were published by our team in a special edition of the IEEE Transactions on Plasma Science (Special Issue on Images in Plasma Science) describing our X-ray and visible light measurements and plasma modeling and simulating studies. Simulation is in many cases the base for the analysis of the photographs. The outcomes of the X-ray and visible light experiments were presented already in earlier issues of the Atomki Annual Report, therefore in this year we concentrate on the results of the simulating studies. The spatial distribution of the three main electron components (cold, warm and hot electron clouds) of the ECR plasmas was simulated by TrapCAD code. TrapCAD is a 'limited' plasma simulation code. The spatial and energy evolution of a large number of electrons can be realistically followed; however, these particles are independent, and no particle interactions are included. In ECRISs, the magnetic trap confines the electrons which keep together the ion component by their space charge. The electrons gain high energies while the ions remain very cold throughout the whole process. Thus, the spatial and energy simulation of the electron component gives much important and numerical information even for the ions. The electron components of ECRISs can artificially be grouped into three populations: cold, warm, and hot electrons. Cold electrons (1-200 eV) have not been heated by the microwave; they are mainly responsible for the visible light emission of the plasma. The energized warm electrons (several kiloelectronvolts) are able to ionize atoms and ions and they are mainly responsible for the characteristic Xray photons emitted by the plasma. Electrons having much higher energy than necessary for

  12. Observation of electron plasma waves in plasma of two-temperature electrons

    International Nuclear Information System (INIS)

    Ikezawa, Shunjiro; Nakamura, Yoshiharu.

    1981-01-01

    Propagation of electron plasma waves in a large and unmagnetized plasma containing two Maxwellian distributions of electrons is studied experimentally. Two kinds of plasma sources which supply electrons of different temperature are used. The temperature ratio is about 3 and the density ratio of hot to cool electrons is varied from 0 to 0.5. A small contamination of hot electrons enhances the Landau damping of the principal mode known as the Bohm-Gross mode. When the density of hot electrons is larger than about 0.2, two modes are observed. The results agree with theoretical dispersion relations when excitation efficiencies of the modes are considered. (author)

  13. Analysis of a high-Tc hot-electron superconducting mixer for terahertz applications

    International Nuclear Information System (INIS)

    Karasik, B.S.; McGrath, W.R.; Gaidis, M.C.

    1997-01-01

    The prospects of a YBa 2 Cu 3 O 7-δ hot-electron bolometer mixer for a THz heterodyne receiver are discussed. The modeled device is a submicron bridge made from a 10-nm-thick film on a high thermal conductance substrate. The mixer performance expected for this device is analyzed in the framework of a two-temperature model which includes heating both of the electrons and the lattice. Also, the contribution of phonon diffusion from the film through the substrate and from the film to the normal metal contacts is evaluated. The intrinsic conversion efficiency and the noise temperature have been calculated as functions of the device size, local oscillator (LO) power, and ambient temperature. Assuming thermal fluctuations and Johnson noise to be the main sources of noise, a minimum single sideband mixer noise temperature of congruent 2000 K is predicted. For our modeled device the intrinsic conversion loss at an intermediate frequency of 2.5 GHz is less than 10 dB and the required LO power is ∼1 endash 10 μW. copyright 1997 American Institute of Physics

  14. Thermoluminescence dosimetry of electronic components from personal objects

    International Nuclear Information System (INIS)

    Beerten, Koen; Woda, Clemens; Vanhavere, Filip

    2009-01-01

    Owing to the existence of ceramic materials inside common personal objects such as cellular phones and USB flash drives, these objects may be very useful in emergency (accident) dosimetry. Here we will present initial results regarding the dosimetric properties as determined by thermoluminescence (TL) from two alumina-rich electronic components from a USB flash drive. The TL method was applied in order to investigate the potential of conventional TL equipment for such purposes. For comparison, the optically stimulated luminescence (OSL) of the components was investigated as well. The studied components are ceramic resonators and alumina-based substrates from electrical resistors. The results show that various TL-related properties such as fading, optical stability and zero-dose response are different for the two investigated components. On the basis of these properties, the ceramic resonator was selected for dose recovery tests using TL and OSL. The given dose could reliably be determined using both methods, assuming that prompt measurement and/or fading correction is possible.

  15. Infrared hot-electron NbN superconducting photodetectors for imaging applications

    International Nuclear Information System (INIS)

    Il'in, K.S.; Gol'tsman, G.N.; Verevkin, A.A.; Sobolewski, Roman

    1999-01-01

    We report an effective quantum efficiency of 340, responsivity >200 A W -1 (>10 4 V W -1 ) and response time of 27±5 ps at temperatures close to the superconducting transition for NbN superconducting hot-electron photodetectors (HEPs) in the near-infrared and optical ranges. Our studies were performed on a few nm thick NbN films deposited on sapphire substrates and patterned into μm-size multibridge detector structures, incorporated into a coplanar transmission line. The time-resolved photoresponse was studied by means of subpicosecond electro-optic sampling with 100 fs wide laser pulses. The quantum efficiency and responsivity studies of our photodetectors were conducted using an amplitude-modulated infrared beam, fibre-optically coupled to the device. The observed picosecond response time and the very high efficiency and sensitivity of the NbN HEPs make them an excellent choice for infrared imaging photodetectors and input optical-to-electrical transducers for superconducting digital circuits. (author)

  16. Oxide formation and precipitation behaviors on interface of F82H steel joints during HIPing and hot pressing

    International Nuclear Information System (INIS)

    Kishimoto, H.; Ono, T.; Sakasegawa, H.; Tanigawa, H.; Ando, M.; Shibayama, T.; Kohno, Y.; Kohyama, A.

    2013-01-01

    Joining technologies for F82H steels are important issues for the development of fusion energy. The hot isostatic pressing (HIP) method is appropriate for consolidating the first wall of the blanket because of the flexibility of the shape of HIPed products. The HIP method is planned for fabricating a complex-shaped first wall component with built-in cooling channels; thus, accumulation of studies of microstructural and mechanical property changes, especially lower toughness of the HIPed joints, is essential. Present research aims to reveal the microstructural evolution of F82H joints fabricated by the HIP method compared with joints fabricated by hot pressing, focusing on the formation of oxides on the interface. F82H joints were characterized using 1/3-scale Charpy V-notch impact test, transmission electron microscope, scanning electron microscope, and electron probe analysis to survey the microstructural characteristics of the interface

  17. Effect of cooler electrons on a compressive ion acoustic solitary wave in a warm ion plasma — Forbidden regions, double layers, and supersolitons

    International Nuclear Information System (INIS)

    Ghosh, S. S.; Sekar Iyengar, A. N.

    2014-01-01

    It is observed that the presence of a minority component of cooler electrons in a three component plasma plays a deterministic role in the evolution of solitary waves, double layers, or the newly discovered structures called supersolitons. The inclusion of the cooler component of electrons in a single electron plasma produces sharp increase in nonlinearity in spite of a decrease in the overall energy of the system. The effect maximizes at certain critical value of the number density of the cooler component (typically 15%–20%) giving rise to a hump in the amplitude variation profile. For larger amplitudes, the hump leads to a forbidden region in the ambient cooler electron concentration which dissociates the overall existence domain of solitary wave solutions in two distinct parameter regime. It is observed that an inclusion of the cooler component of electrons as low as < 1% affects the plasma system significantly resulting in compressive double layers. The solution is further affected by the cold to hot electron temperature ratio. In an adequately hotter bulk plasma (i.e., moderately low cold to hot electron temperature ratio), the parameter domain of compressive double layers is bounded by a sharp discontinuity in the corresponding amplitude variation profile which may lead to supersolitons

  18. Effect of cooler electrons on a compressive ion acoustic solitary wave in a warm ion plasma — Forbidden regions, double layers, and supersolitons

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, S. S., E-mail: sukti@iigs.iigm.res.in [Indian Institute of Geomagnetism, New Panvel, Navi Mumbai 410218 (India); Sekar Iyengar, A. N. [Plasma Physics Division, Saha Institute of Nuclear Physics, Kolkata 700064 (India)

    2014-08-15

    It is observed that the presence of a minority component of cooler electrons in a three component plasma plays a deterministic role in the evolution of solitary waves, double layers, or the newly discovered structures called supersolitons. The inclusion of the cooler component of electrons in a single electron plasma produces sharp increase in nonlinearity in spite of a decrease in the overall energy of the system. The effect maximizes at certain critical value of the number density of the cooler component (typically 15%–20%) giving rise to a hump in the amplitude variation profile. For larger amplitudes, the hump leads to a forbidden region in the ambient cooler electron concentration which dissociates the overall existence domain of solitary wave solutions in two distinct parameter regime. It is observed that an inclusion of the cooler component of electrons as low as < 1% affects the plasma system significantly resulting in compressive double layers. The solution is further affected by the cold to hot electron temperature ratio. In an adequately hotter bulk plasma (i.e., moderately low cold to hot electron temperature ratio), the parameter domain of compressive double layers is bounded by a sharp discontinuity in the corresponding amplitude variation profile which may lead to supersolitons.

  19. Sheath and heat flow of a two-electron-temperature plasma in the presence of electron emission

    International Nuclear Information System (INIS)

    Sato, Kunihiro; Miyawaki, Fujio

    1992-01-01

    The electrostatic sheath and the heat flow of a two-electron-temperature plasma in the presence of electron emission are investigated analytically. It is shown that the energy flux is markedly enhanced to a value near the electron free-flow energy flux as a result of considerable reduction of the sheath potential due to electron emission if the fraction of hot electrons at the sheath edge is much smaller than one. If the hot- to cold-electron temperature ratio is of the order of ten and the hot electron density is comparable to the cold electron density, the action of the sheath as a thermal insulator is improved as a result of suppression of electron emission due to the space-charge effect of hot electrons. (author)

  20. Response to open-quote open-quote Comment on open-quote Electron acoustic surface waves in a two-electron component plasma close-quote close-quote close-quote [Phys. Fluids B 5, 4502 (1993)

    International Nuclear Information System (INIS)

    Bharuthram, R.; Misthry, S.S.; Yu, M.Y.

    1996-01-01

    Three points are discussed: (a) the models of boundary conditions; (b) the mean velocity of hot electrons and their density; (c) the validity of the term open-quote open-quote electron acoustic waves.close-quote close-quote

  1. Retrospective dosimetry with alumina substrate from electronic components

    International Nuclear Information System (INIS)

    Ekendahl, D.; Judas, L.

    2012-01-01

    Alumina substrate can be found in electronic components used in portable electronic devices. The material is radiation sensitive and can be applied in dosimetry using thermally or optically stimulated luminescence. Electronic portable devices such as mobile phones, USB flash discs, mp3 players, etc., which are worn close to the body, can represent personal dosemeters for members of the general public in situations of large-scale radiation accidents or malevolent acts with radioactive materials. This study investigated dosimetric properties of alumina substrates and aspects of using mobile phones as personal dosemeters. The alumina substrates exhibited favourable dosimetry characteristics. However, anomalous fading had to be properly corrected in order to achieve sufficient precision in dose estimate. Trial dose reconstruction performed by means of two mobile phones proved that mobile phones can be used for reconstruction of personal doses. (authors)

  2. Hot-Electron Bolometer Mixers on Silicon-on-Insulator Substrates for Terahertz Frequencies

    Science.gov (United States)

    Skalare, Anders; Stern, Jeffrey; Bumble, Bruce; Maiwald, Frank

    2005-01-01

    A terahertz Hot-Electron Bolometer (HEB) mixer design using device substrates based on Silicon-On-Insulator (SOI) technology is described. This substrate technology allows very thin chips (6 pm) with almost arbitrary shape to be manufactured, so that they can be tightly fitted into a waveguide structure and operated at very high frequencies with only low risk for power leakages and resonance modes. The NbTiN-based bolometers are contacted by gold beam-leads, while other beamleads are used to hold the chip in place in the waveguide test fixture. The initial tests yielded an equivalent receiver noise temperature of 3460 K double-sideband at a local oscillator frequency of 1.462 THz and an intermediate frequency of 1.4 GHz.

  3. Change On The S-Z Effect Induced By The Cooling Flow CF On The Hot Electronic Gas At The Center OF The Clusters Of Galaxies

    Directory of Open Access Journals (Sweden)

    Enkelejd Caca

    2015-06-01

    Full Text Available ABSTRACT Building more accurate profiles for temperature and density of hot electronic gas concentrated in the center of clusters of galaxies is a constant problem in survey of Sunyeav Zeldovich effect SZ. An effect that consists in the inverse Compton effect of the hot electronic gas interacting with Cosmic Microwave Back- ground CMB photons passing through Intra Cluster Medium ICM. So far the Isothermal model is used for temperature profiling in the calculation of the inverse Compton effect but based on the recent improved observations from satellites which showed that the hot electronic gas presents a feature called Cooling Flow CF. Temperatures in this model differs towards the edges of the Clusters of Galaxies leading to a change on the Compton parameter in comparison with Isothermal model. In this paper are processed data provided by X-ray satellite Chandra. The X-ray analysis is based on two models for the electron density and temperature profile. A sample of 12 clusters of galaxies are analyzed and by building the temperature profiles using CF model the differences on the Compton parameter are 10-100 in comparison with Isothermal model. Therefore to increase the accuracy of evaluation of the Compton parameter we should take into account the change of the electronic gas tempera- ture change that affect changes in both CMB spectrum and temperature from SZ effect.

  4. Observation of Flat Electron Temperature Profiles in the Lithium Tokamak Experiment

    International Nuclear Information System (INIS)

    Boyle, D. P.; Majeski, R.; Schmitt, J. C.; Auburn University, AL; Hansen, C.

    2017-01-01

    It has been predicted for over a decade that low-recycling plasma-facing components in fusion devices would allow high edge temperatures and flat or nearly flat temperature profiles. In recent experiments with lithium wall coatings in the Lithium Tokamak Experiment (LTX), a hot edge (> 200 eV) and flat electron temperature profiles have been measured following the termination of external fueling. In this work, reduced recycling was demonstrated by retention of ~ 60% of the injected hydrogen in the walls following the discharge. Electron energy confinement followed typical Ohmic confinement scaling during fueling, but did not decrease with density after fueling terminated, ultimately exceeding the scaling by ~ 200% . Lastly, achievement of the low-recycling, hot edge regime has been an important goal of LTX and lithium plasma-facing component research in general, as it has potentially significant implications for the operation, design, and cost of fusion devices.

  5. Application of principal component and factor analyses in electron spectroscopy

    International Nuclear Information System (INIS)

    Siuda, R.; Balcerowska, G.

    1998-01-01

    Fundamentals of two methods, taken from multivariate analysis and known as principal component analysis (PCA) and factor analysis (FA), are presented. Both methods are well known in chemometrics. Since 1979, when application of the methods to electron spectroscopy was reported for the first time, they became to be more and more popular in different branches of electron spectroscopy. The paper presents examples of standard applications of the method of Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS), and electron energy loss spectroscopy (EELS). Advantages one can take from application of the methods, their potentialities as well as their limitations are pointed out. (author)

  6. Hot stamping advanced manufacturing technology of lightweight car body

    CERN Document Server

    Hu, Ping; He, Bin

    2017-01-01

    This book summarizes the advanced manufacturing technology of original innovations in hot stamping of lightweight car body. A detailed description of the technical system and basic knowledge of sheet metal forming is given, which helps readers quickly understand the relevant knowledge in the field. Emphasis has been placed on the independently developed hot stamping process and equipment, which help describe the theoretical and experimental research on key problems involving stress field, thermal field and phase transformation field in hot stamping process. Also, a description of the formability at elevated temperature and the numerical simulation algorithms for high strength steel hot stamping is given in combination with the experiments. Finally, the book presents some application cases of hot stamping technology such as the lightweight car body design using hot stamping components and gradient hardness components, and the cooling design of the stamping tool. This book is intended for researchers, engineers...

  7. Additive Manufacturing of IN100 Superalloy Through Scanning Laser Epitaxy for Turbine Engine Hot-Section Component Repair: Process Development, Modeling, Microstructural Characterization, and Process Control

    Science.gov (United States)

    Acharya, Ranadip; Das, Suman

    2015-09-01

    This article describes additive manufacturing (AM) of IN100, a high gamma-prime nickel-based superalloy, through scanning laser epitaxy (SLE), aimed at the creation of thick deposits onto like-chemistry substrates for enabling repair of turbine engine hot-section components. SLE is a metal powder bed-based laser AM technology developed for nickel-base superalloys with equiaxed, directionally solidified, and single-crystal microstructural morphologies. Here, we combine process modeling, statistical design-of-experiments (DoE), and microstructural characterization to demonstrate fully metallurgically bonded, crack-free and dense deposits exceeding 1000 μm of SLE-processed IN100 powder onto IN100 cast substrates produced in a single pass. A combined thermal-fluid flow-solidification model of the SLE process compliments DoE-based process development. A customized quantitative metallography technique analyzes digital cross-sectional micrographs and extracts various microstructural parameters, enabling process model validation and process parameter optimization. Microindentation measurements show an increase in the hardness by 10 pct in the deposit region compared to the cast substrate due to microstructural refinement. The results illustrate one of the very few successes reported for the crack-free deposition of IN100, a notoriously "non-weldable" hot-section alloy, thus establishing the potential of SLE as an AM method suitable for hot-section component repair and for future new-make components in high gamma-prime containing crack-prone nickel-based superalloys.

  8. Light and Redox Switchable Molecular Components for Molecular Electronics

    NARCIS (Netherlands)

    Browne, Wesley R.; Feringa, Bernard

    2010-01-01

    The field of molecular and organic electronics has seen rapid progress in recent years, developing from concept and design to actual demonstration devices in which both single molecules and self-assembled monolayers are employed as light-responsive components. Research in this field has seen

  9. Physical basis of power conversion of energy fluctuations of hot electrons

    Energy Technology Data Exchange (ETDEWEB)

    Yater, J C

    1983-12-01

    The design of an experimental reversible-energy-fluctuation (REF) solar converter using hot nonequilibrated (HNE) electrons is presented. The physical principles are introduced, and an idealized model is described and analyzed in terms of radiation and electron-thermalization losses and first-to-third-layer transfer times. It is shown that the 93-percent limiting conversion efficiency can be approached in both a two-level and an N-level model, even in larger-scale circuits. On the other hand, as circuit size is decreased below 100 nm, the maximum power output can exceed 10 MW/sq m. The materials and thicknesses to be used in an experimental thin-film version of the REF device are outlined, including a 10-60-nm-thick Cd3As2 or alpha-Sn absorbing layer, a 4-10-nm-thick doped-semiconductor or semimetal quantum-well layer, and a Schottky-barrier diode layer comprising a 4-10-nm-thick Pb sheet on a 5-20-nm-thick p-GaAs film. Experiments at lattice temperatures of from 300 to 1 K with input radiation at wavelengths from 1 micron to the solar spectrum and intensities from zero to 1 mW are planned to determine whether the predicted practical efficiency of 80 percent can be obtained. 19 references.

  10. Auto-correlation of velocity-fluctuations and frequency-dependent diffusion constant for hot electrons

    International Nuclear Information System (INIS)

    Roy, M.D.; Nag, B.R.

    1981-01-01

    A method has been developed for determining the auto-correlation functions of the fluctuations in the transverse and the parallel components of hot carrier-velocity in a semiconductor by Monte Carlo simulation. The functions for electrons in InSb are determined by this method for applied electric fields of 50 V/cm, 75 V/cm, and 100 V/cm. With increasing value of the time interval the transverse auto-correlation function fall nearly exponentially to zero, but the parallel function falls sharply to a negative peak, then rises to positive values and finally becomes zero. The interval beyond which the auto-correlation function is zero and the correlation time are also evaluated. The correlation time is found to be approximately 1.6 times the relaxation time calculated from the chord mobility. The effect of the flight sampling time on the value of variance of the displacement, is investigated in terms of the low frequency diffusion constants, determined from the variation of the correlation functions. It is found that the diffusion constants become independent of the sampling time if it is of the order of one hundred times the relaxation time. The frequency-dependent diffusion constants are calculated from the correlation functions. The transverse diffusion constant falls monotonically with frequency for all the field strengths studied. The parallel diffusion constant has similar variation for the lower fields (50 V/cm and 75 V/cm) but it has a peak at about 44 GHz for the field of 100 V/cm. (orig.)

  11. Modification Of The Electron Energy Distribution Function During Lithium Experiments On The National Spherical Torus Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Jaworski, M A; Gray, T K; Kaita, R; Kallman, J; Kugel, H; LeBlanc, B; McLean, A; Sabbagh, S A; Soukanovskii, V; Stotler, D P

    2011-06-03

    The National Spherical Torus Experiment (NSTX) has recently studied the use of a liquid lithium divertor (LLD). Divertor Langmuir probes have also been installed for making measurements of the local plasma conditions. A non-local probe interpretation method is used to supplement the classical probe interpretation and obtain measurements of the electron energy distribution function (EEDF) which show the occurrence of a hot-electron component. Analysis is made of two discharges within a sequence that exhibited changes in plasma fueling efficiency. It is found that the local electron temperature increases and that this increase is most strongly correlated with the energy contained within the hot-electron population. Preliminary interpretative modeling indicates that kinetic effects are likely in the NSTX.

  12. In-service inspection of electronics components, circuits and nuclear radiation detectors

    International Nuclear Information System (INIS)

    Darbhe, M.D.

    2002-01-01

    A nuclear reactor is a complex process plant. Like a nuclear power plant, the research reactors also employ various nuclear and process systems, the scope and number of such systems being plant-specific. In-service inspection of these systems is an important requirement and is applied at various levels of their constituent units such as detectors, electronics components, circuits and integrated systems. The sensors used cover a wide range such as neutronic, radiation, process (pressure, temperature, flow, level) and many others. The present discussion is limited to neutronic and radiation detectors. The electronic components used normally consist of passive components like resistors, capacitors, semiconductor components like diodes, transistors, analog integrated circuits and digital integrated circuits and electromagnetic relays, to name a few. In order to have a comprehensive surveillance and ISI plan, over the entire plant life, it is necessary to understand various mechanisms, which degrade the performance of these systems. These are discussed initially and later various ISI methods that are used on component-circuit or system level, to ensure optimum system performance, are discussed. The computerised systems, because of hardware and software considerations, have to be given special attention, and the same are discussed briefly

  13. Hot Charge Carrier Transmission from Plasmonic Nanostructures

    Science.gov (United States)

    Christopher, Phillip; Moskovits, Martin

    2017-05-01

    Surface plasmons have recently been harnessed to carry out processes such as photovoltaic current generation, redox photochemistry, photocatalysis, and photodetection, all of which are enabled by separating energetic (hot) electrons and holes—processes that, previously, were the domain of semiconductor junctions. Currently, the power conversion efficiencies of systems using plasmon excitation are low. However, the very large electron/hole per photon quantum efficiencies observed for plasmonic devices fan the hope of future improvements through a deeper understanding of the processes involved and through better device engineering, especially of critical interfaces such as those between metallic and semiconducting nanophases (or adsorbed molecules). In this review, we focus on the physics and dynamics governing plasmon-derived hot charge carrier transfer across, and the electronic structure at, metal-semiconductor (molecule) interfaces, where we feel the barriers contributing to low efficiencies reside. We suggest some areas of opportunity that deserve early attention in the still-evolving field of hot carrier transmission from plasmonic nanostructures to neighboring phases.

  14. Light and redox switchable molecular components for molecular electronics.

    Science.gov (United States)

    Browne, Wesley R; Feringa, Ben L

    2010-01-01

    The field of molecular and organic electronics has seen rapid progress in recent years, developing from concept and design to actual demonstration devices in which both single molecules and self-assembled monolayers are employed as light-responsive components. Research in this field has seen numerous unexpected challenges that have slowed progress and the initial promise of complex molecular-based computers has not yet been realised. Primarily this has been due to the realisation at an early stage that molecular-based nano-electronics brings with it the interface between the hard (semiconductor) and soft (molecular) worlds and the challenges which accompany working in such an environment. Issues such as addressability, cross-talk, molecular stability and perturbation of molecular properties (e.g., inhibition of photochemistry) have nevertheless driven development in molecular design and synthesis as well as our ability to interface molecular components with bulk metal contacts to a very high level of sophistication. Numerous groups have played key roles in progressing this field not least teams such as those led by Whitesides, Aviram, Ratner, Stoddart and Heath. In this short review we will however focus on the contributions from our own group and those of our collaborators, in employing diarylethene based molecular components.

  15. An ALARA-conscious hot particle control program

    International Nuclear Information System (INIS)

    Doolittle, W.W.; Bredvad, R.S.; Bevelacqua, J.J.

    1992-01-01

    In 1989 approximately twenty-five percent of the radiation dose received by the Point Beach Nuclear Plant (PBNP) Health Physics group was due to its hot particle control program. The Health Physics group initiated a review of the program with the objective of decreasing the dose expenditure for hot particle control while maintaining a high standard for hot particle detection and control. In this paper the methods and results of this evaluation are described. The components of the hot particle control program, rules of thumb, and radionuclide composition at PBNP are presented

  16. X-ray investigations of the hot ISM

    Science.gov (United States)

    Sanders, W. T.

    1993-01-01

    At energies less than one keV, the intensity of the galactic x-ray background dominates that of the extragalactic background in almost every direction on the sky. Below 1/4 keV, the galactic x-ray background has a galactic stellar component, but the dominant emitter seems to be hot interstellar matter. The origin of the general 3/4 keV x-ray background remains uncertain, but one component must also be the contribution from hot interstellar matter. An overview is given of recent x-ray investigations of the hot interstellar medium using data from the ROSAT X-ray Telescope/Position-Sensitive Proportional Counter (XRT/PSPC) instrument. Several prominent features in the low energy x-ray background that are interpreted as fossil supernova remnants are discussed.

  17. 77 FR 27078 - Certain Electronic Devices, Including Mobile Phones and Tablet Computers, and Components Thereof...

    Science.gov (United States)

    2012-05-08

    ... Phones and Tablet Computers, and Components Thereof; Notice of Receipt of Complaint; Solicitation of... entitled Certain Electronic Devices, Including Mobile Phones and Tablet Computers, and Components Thereof... the United States after importation of certain electronic devices, including mobile phones and tablet...

  18. Lateral terahertz hot-electron bolometer based on an array of Sn nanothreads in GaAs

    Science.gov (United States)

    Ponomarev, D. S.; Lavrukhin, D. V.; Yachmenev, A. E.; Khabibullin, R. A.; Semenikhin, I. E.; Vyurkov, V. V.; Ryzhii, M.; Otsuji, T.; Ryzhii, V.

    2018-04-01

    We report on the proposal and the theoretical and experimental studies of the terahertz hot-electron bolometer (THz HEB) based on a gated GaAs structure like the field-effect transistor with the array of parallel Sn nanothreads (Sn-NTs). The operation of the HEB is associated with an increase in the density of the delocalized electrons due to their heating by the incoming THz radiation. The quantum and the classical device models were developed, the quantum one was based on the self-consistent solution of the Poisson and Schrödinger equations, the classical model involved the Poisson equation and density of states omitting quantization. We calculated the electron energy distributions in the channels formed around the Sn-NTs for different gate voltages and found the fraction of the delocalized electrons propagating across the energy barriers between the NTs. Since the fraction of the delocalized electrons strongly depends on the average electron energy (effective temperature), the proposed THz HEB can exhibit an elevated responsivity compared with the HEBs based on more standard heterostructures. Due to a substantial anisotropy of the device structure, the THz HEB may demonstrate a noticeable polarization selectivity of the response to the in-plane polarized THz radiation. The features of the THz HEB might be useful in their practical applications in biology, medicine and material science.

  19. Distinguishing of Ile/Leu amino acid residues in the PP3 protein by (hot) electron capture dissociation in Fourier transform ion cyclotron resonance mass spectrometry

    DEFF Research Database (Denmark)

    Kjeldsen, Frank; Haselmann, Kim F; Sørensen, Esben Skipper

    2003-01-01

    In hot electron capture dissociation (HECD), multiply protonated polypeptides fragment upon capturing approximately 11-eV electrons. The excess of energy upon the primary c, z* cleavage induces secondary fragmentation in z* fragments. The resultant w ions allow one to distinguish between the isom...

  20. Hot tearing studies in AA5182

    Science.gov (United States)

    van Haaften, W. M.; Kool, W. H.; Katgerman, L.

    2002-10-01

    One of the major problems during direct chill (DC) casting is hot tearing. These tears initiate during solidification of the alloy and may run through the entire ingot. To study the hot tearing mechanism, tensile tests were carried out in semisolid state and at low strain rates, and crack propagation was studied in situ by scanning electron microscopy (SEM). These experimentally induced cracks were compared with hot tears developed in an AA5182 ingot during a casting trial in an industrial research facility. Similarities in the microstructure of the tensile test specimens and the hot tears indicate that hot tearing can be simulated by performing tensile tests at semisolid temperatures. The experimental data were compared with existing hot tearing models and it was concluded that the latter are restricted to relatively high liquid fractions because they do not take into account the existence of solid bridges in the crack.

  1. Hot gas filtration: Investigations to remove gaseous pollutant components out of flue gas during hot gas filtration. Final report; HGR: Untersuchung zur Minimierung von gasfoermigen Schadstoffen aus Rauchgasen bei der Heissgasfiltration. Abschlussbericht

    Energy Technology Data Exchange (ETDEWEB)

    Christ, A; Gross, R; Renz, U

    1998-07-01

    Power plants with gas and steam turbines in pressurized fluidized bed or pressurized gasification processes enable power generation of coal with high efficiency and little emissions. To run these plants the cleaning of the flue gas is necessary before entering the turbines under the conditions of high temperature and pressure. Ceramic filter elements are the most probable method for hot gas cleaning. A simultaneous reduction of gaseous pollutant components under these conditions could help to make the whole process more efficient. The aim of the project is to integrate the catalytic reduction of carbon monoxide, hydrocarbons and nitric oxides into the hot gas filtration with ceramic filter elements as a one step mecanism. The project is focused on: - the catalytic behaviour of ferruginous ashes of brown coal, - the effectiveness of calcinated aluminates as a catalyst to remove uncombusted hydrocarbons in a hot gas filtration unit, - numerical simulation of the combined removal of particles and gaseous pollutant components out of the flue gas. (orig.) [Deutsch] Gas- und Dampfturbinen-Kraftwerke mit Druckwirbelschicht- oder mit Druckvergasungsverfahren ermoeglichen die Verstromung von Kohle mit hohem Wirkungsgrad und niedrigen Emissionen. Eine Voraussetzung fuer den Betrieb dieser Anlagen ist die Entstaubung der Rauchgase bei hohen Temperaturen und Druecken. Abreinigungsfilter mit keramischen Elementen werden dazu eingesetzt. Eine Reduzierung gasfoermiger Schadstoffe unter den gleichen Bedingungen koennte die Rauchgaswaesche ersetzen. Ziel des Gesamtvorhabens ist es, die Integration von Heissgasfiltration und katalytischem Abbau der Schadstoffe Kohlenmonoxid, Kohlenwasserstoffe und Stickoxide in einem Verfahrensschritt zu untersuchen. Die Arbeitsschwerpunkte dieses Teilvorhabens betreffen - die katalytische Wirkung eisenhaltiger Braunkohlenaschen, - die Wirksamkeit des Calciumaluminats als Katalysator des Abbaus unverbrannter Kohlenwasserstoffe im Heissgasfilter

  2. Potential Formation in Front of an Electron Emitting Electrode in a Two-Electron Temperature Plasma

    International Nuclear Information System (INIS)

    Gyergyek, T.; Cercek, M.; Erzen, D.

    2003-01-01

    Plasma potential formation in the pre-sheath region of a floating electron emitting electrode (collector) is studied theoretically in a two-electron-temperature plasma using a static kinetic plasma-sheath model. Dependence of the collector floating potential, the plasma potential in the pre-sheath region, and the critical emission coefficient on the hot electron density and temperature is calculated. It is found that for high hot to cool electron temperature ratio a double layer like solutions exist in a certain range of hot to cool electron densities

  3. Experimental Route to Scanning Probe Hot Electron Nanoscopy (HENs) Applied to 2D Material

    KAUST Repository

    Giugni, Andrea

    2017-06-09

    This paper presents details on a new experimental apparatus implementing the hot electron nanoscopy (HENs) technique introduced for advanced spectroscopies on structure and chemistry in few molecules and interface problems. A detailed description of the architecture used for the laser excitation of surface plasmons at an atomic force microscope (AFM) tip is provided. The photogenerated current from the tip to the sample is detected during the AFM scan. The technique is applied to innovative semiconductors for applications in electronics: 2D MoS2 single crystal and a p-type SnO layer. Results are supported by complementary scanning Kelvin probe microscopy, traditional conductive AFM, and Raman measurements. New features highlighted by HEN technique reveal details of local complexity in MoS2 and polycrystalline structure of SnO at nanometric scale otherwise undetected. The technique set in this paper is promising for future studies in nanojunctions and innovative multilayered materials, with new insight on interfaces.

  4. Study of field induced hot-electron emission using the composite microemitters with varying dielectric layer thickness

    International Nuclear Information System (INIS)

    Mousa, M.S.

    1987-07-01

    The analysis of the measurements obtained from the of field emission of electrons from composite metal-insulator (M-I) micropoint cathodes, using the combination of a high resolution electron spectrometer and a field emission microscope, has been presented. Results obtained describe the reversible current-voltage characteristic, emission images and electron energy distribution measurements of both thin and the optimum thick coatings. The observed effects, e.g. the threshold switch-on phenomena and the field-dependence of the F.W.H.M. and energy shift of the electron spectra have been identified in terms of a field-induced hot-electron emission (FIHEE) mechanism resulting from field penetration in the insulating film where conducting channels are formed. The theoretical implications accounts for the channels field intensification mechanism and the conduction properties with applied field, and the F.W.H.M. dependence on electron temperature. The control of the emission process at low fields by the M-I contact junction and at high fields by the bulk properties of the insulator have also been accounted for. These experimental and theoretical findings have been shown to be consistent with recently published data on M-I microstructures on broad-area (BA) high-voltage electrodes. (author). 18 refs, 6 figs

  5. Contribution to the determination of priority constructive influences on the hot crack initiation of welded components; Beitrag zur Ermittlung vorrangig konstruktiver Einflussgroessen auf die Heissrissinitiierung an geschweissten Bauteilen

    Energy Technology Data Exchange (ETDEWEB)

    Gollnow, Christian

    2015-07-01

    The previous research results do not allow a general hot crack characterisation although a variety of experimental and numerical knowledge is available. The reason for this is mainly the large number of influencing factors that complicate a complete description of the hot cracking phenomenon and especially solidification cracking. The hot crack formation and thus the solidification crack initiation can be described by the interaction of process, metallurgy and design. However, the literature examination shows that in the solidifaction crack characterisation the influence of the design aspect is often underestimated. The pre-stresses of the structural components is up to now not considered as an essential cause for the formation of solidification cracks. The evaluation of the influence of the various parameters is presented partly inconsistent. In addition, the targeted presentation of the design influence with respect to the solidification cracks in the weld is because the limited transferability of the various component-specific stresses on a laboratory scale and thus to the respective hot cracking tests restricted. Hence, the difficulty to transfer the results between laboratory specimen and component as well as the general hot crack characterisation is given. In this work the different types of stresses from the component welding in the laboratory and to quantify experimentally the solidification crack critical values, displacements and displacement rates were detected. In this regard external loaded hot cracking tests were carried out by using the advantages of contactless measurement techniques close to the weld and to analyse the welding process with respect to various local and global design-specific factors influencing the formation of solidification cracks in high alloyed steel. These investigations were performed on austenitic (1.4828) and ferritic (1.4509) materials with different mechanical and technological properties. To reflect the praxis relevant

  6. Magnetic field effects on runaway electron energy deposition in plasma facing materials and components

    International Nuclear Information System (INIS)

    Niemer, K.A.; Gilligan, J.G.

    1992-01-01

    This paper reports magnetic field effects on runaway electron energy deposition in plasma facing materials and components is investigated using the Integrated TIGER Series. The Integrated TIGER Series is a set of time-independent coupled electron/photon Monte Carlo transport codes which perform photon and electron transport, with or without macroscopic electric and magnetic fields. A three-dimensional computational model of 100 MeV electrons incident on a graphite block was used to simulate runawayelectrons striking a plasma facing component at the edge of a tokamak. Results show that more energy from runaway electrons will be deposited in a material that is in the presence of a magnetic field than in a material that is in the presence of no field. For low angle incident runaway electrons in a strong magnetic field, the majority of the increased energy deposition is near the material surface with a higher energy density. Electrons which would have been reflected with no field, orbit the magnetic field lines and are redeposited in the material surface, resulting in a substantial increase in surface energy deposition. Based on previous studies, the higher energy deposition and energy density will result in higher temperatures which are expected to cause more damage to a plasma facing component

  7. Remarks on theoretical hot-atom chemistry

    International Nuclear Information System (INIS)

    Inokuti, Mitio

    1993-01-01

    The publication of the 'Handbook of Hot Atom Chemistry', following the earlier volume 'Recent Trend and Application', was a major milestone in physical chemistry. Theoretical treatments of hot atom chemistry must address two classes of problems. The first class concerns the individual collisions of hot atoms with other atoms or molecules. The second class concerns the description of the consequences of the many collisions of hot atoms and their chemical environment. Most of the remarks pertain to the problems of the first class. The central issue is the adiabaticity of nuclear motions versus electronic motions. To be precise, any atomic core motion should be mentioned rather than pure nuclear motion, because tightly bound core electrons are largely irrelevant to the chemistry. When nuclear motions are sufficiently slow, or for other reasons that can be regarded as adiabatic, the collision problem is basically straightforward, therefore, interatomic and intermolecular forces can be assumed, and their consequences for nuclear motions are calculable in principle. In the case of non-adiabaticity being important, much more difficult problems arise, and it is briefly discussed, and the work by Phelps is cited. (K.I.)

  8. Component-Level Electronic-Assembly Repair (CLEAR) Operational Concept

    Science.gov (United States)

    Oeftering, Richard C.; Bradish, Martin A.; Juergens, Jeffrey R.; Lewis, Michael J.; Vrnak, Daniel R.

    2011-01-01

    This Component-Level Electronic-Assembly Repair (CLEAR) Operational Concept document was developed as a first step in developing the Component-Level Electronic-Assembly Repair (CLEAR) System Architecture (NASA/TM-2011-216956). The CLEAR operational concept defines how the system will be used by the Constellation Program and what needs it meets. The document creates scenarios for major elements of the CLEAR architecture. These scenarios are generic enough to apply to near-Earth, Moon, and Mars missions. The CLEAR operational concept involves basic assumptions about the overall program architecture and interactions with the CLEAR system architecture. The assumptions include spacecraft and operational constraints for near-Earth orbit, Moon, and Mars missions. This document addresses an incremental development strategy where capabilities evolve over time, but it is structured to prevent obsolescence. The approach minimizes flight hardware by exploiting Internet-like telecommunications that enables CLEAR capabilities to remain on Earth and to be uplinked as needed. To minimize crew time and operational cost, CLEAR exploits offline development and validation to support online teleoperations. Operational concept scenarios are developed for diagnostics, repair, and functional test operations. Many of the supporting functions defined in these operational scenarios are further defined as technologies in NASA/TM-2011-216956.

  9. Ion acoustic solitons in a plasma with two-temperature kappa-distributed electrons

    International Nuclear Information System (INIS)

    Baluku, T. K.; Hellberg, M. A.

    2012-01-01

    Existence domains and characteristics of ion acoustic solitons are studied in a two-temperature electron plasma with both electron components being kappa-distributed, as found in Saturn's magnetosphere. As is the case for double-Boltzmann electrons, solitons of both polarities can exist over restricted ranges of fractional hot electron density ratio for this plasma model. Low κ values, which indicate increased suprathermal particles in the tail of the distribution, yield a smaller domain in the parameter space of hot density fraction and normalized soliton velocity (f, M), over which both soliton polarities are supported for a given plasma composition (the coexistence region). For some density ratios that support coexistence, solitons occur even at the lowest (critical) Mach number (i.e., at the acoustic speed), as found recently for a number of other plasma models. Like Maxwellians, low-κ distributions also support positive potential double layers over a narrow range of low fractional cool electron density (<10%).

  10. Ion acoustic solitons in a plasma with two-temperature kappa-distributed electrons

    Energy Technology Data Exchange (ETDEWEB)

    Baluku, T. K.; Hellberg, M. A. [School of Physics, University of KwaZulu-Natal, Private Bag X54001, Durban 4000 (South Africa)

    2012-01-15

    Existence domains and characteristics of ion acoustic solitons are studied in a two-temperature electron plasma with both electron components being kappa-distributed, as found in Saturn's magnetosphere. As is the case for double-Boltzmann electrons, solitons of both polarities can exist over restricted ranges of fractional hot electron density ratio for this plasma model. Low {kappa} values, which indicate increased suprathermal particles in the tail of the distribution, yield a smaller domain in the parameter space of hot density fraction and normalized soliton velocity (f, M), over which both soliton polarities are supported for a given plasma composition (the coexistence region). For some density ratios that support coexistence, solitons occur even at the lowest (critical) Mach number (i.e., at the acoustic speed), as found recently for a number of other plasma models. Like Maxwellians, low-{kappa} distributions also support positive potential double layers over a narrow range of low fractional cool electron density (<10%).

  11. Surface analysis of WC--Co composite materials (2) Quantitative Auger electron spectrometry

    International Nuclear Information System (INIS)

    Tongson, L.L.; Biggers, J.V.; Dayton, G.O.; Bind, J.M.; Knox, B.E.

    1978-01-01

    The unique sensitivity of Auger electron spectrometry (AES) to combined carbon has been exploited in measuring the surface compositions of hot-pressed, conventionally sintered and mixed powders of WC--Co composite materials. AES sensitivity factors for tungsten and carbon (in WC) relative to cobalt were determined. The concentrations of the major elements in hot-pressed samples measured with AES using the relative sensitivity method were compared to those obtained independently by electron microprobe (EMP) and x-ray fluorescence (XRF) techniques. Corollary studies using ion scattering spectrometry (ISS) showed the absence of (1) matrix effects in the AES measurements, (2) preferential sputtering during ion bombardment, and (3) deposition of the easier-to-sputter component (cobalt) onto WC

  12. Reliability considerations of electronics components for the deep underwater muon and neutrino detection system

    International Nuclear Information System (INIS)

    Leskovar, B.

    1980-02-01

    The reliability of some electronics components for the Deep Underwater Muon and Neutrino Detection (DUMAND) System is discussed. An introductory overview of engineering concepts and technique for reliability assessment is given. Component reliability is discussed in the contest of major factors causing failures, particularly with respect to physical and chemical causes, process technology and testing, and screening procedures. Failure rates are presented for discrete devices and for integrated circuits as well as for basic electronics components. Furthermore, the military reliability specifications and standards for semiconductor devices are reviewed

  13. Proximity effect and hot-electron diffusion in Ag/Al2O3/Al tunnel junctions

    International Nuclear Information System (INIS)

    Netel, H.; Jochum, J.; Labov, S.E.; Mears, C.A.; Frank, M.; Chow, D.; Lindeman, M.A.; Hiller, L.J.

    1997-01-01

    We have fabricated Ag/Al 2 O 3 /Al tunnel junctions on Si substrates using a new process. This process was developed to fabricate superconducting tunnel junctions (STJs) on the surface of a superconductor. These junctions allow us to study the proximity effect of a superconducting Al film on a normal metal trapping layer. In addition, these devices allow us to measure the hot-electron diffusion constant using a single junction. Lastly these devices will help us optimize the design and fabrication of tunnel junctions on the surface of high-Z, ultra-pure superconducting crystals. 5 refs., 8 figs

  14. Phase-locking of a terahertz solid-state source using a superconducting hot-electron bolometer mixer

    International Nuclear Information System (INIS)

    Miao, W; Zhang, W; Zhou, K M; Li, S L; Zhang, K; Duan, W Y; Yao, Q J; Shi, S C

    2013-01-01

    We report on a scheme whereby the local-oscillator (LO) of a THz heterodyne receiver can be phase-locked by the mixer of the heterodyne receiver. This scheme is demonstrated for the phase-locking of an 847.6 GHz Gunn oscillator and multiplier chain combined source with a superconducting hot-electron bolometer (HEB) mixer. We show that with this technique the phase-locked beat signal can reach a signal-to-noise ratio higher than 70 dB in a resolution bandwidth (RBW) of 1 Hz. This phase-locking scheme should find good use in THz heterodyne spectrometers. (paper)

  15. Reactivating Catalytic Surface: Insights into the Role of Hot Holes in Plasmonic Catalysis.

    Science.gov (United States)

    Peng, Tianhuan; Miao, Junjian; Gao, Zhaoshuai; Zhang, Linjuan; Gao, Yi; Fan, Chunhai; Li, Di

    2018-03-01

    Surface plasmon resonance of coinage metal nanoparticles is extensively exploited to promote catalytic reactions via harvesting solar energy. Previous efforts on elucidating the mechanisms of enhanced catalysis are devoted to hot electron-induced photothermal conversion and direct charge transfer to the adsorbed reactants. However, little attention is paid to roles of hot holes that are generated concomitantly with hot electrons. In this work, 13 nm spherical Au nanoparticles with small absorption cross-section are employed to catalyze a well-studied glucose oxidation reaction. Density functional theory calculation and X-ray absorption spectrum analysis reveal that hot holes energetically favor transferring catalytic intermediates to product molecules and then desorbing from the surface of plasmonic catalysts, resulting in the recovery of their catalytic activities. The studies shed new light on the use of the synergy of hot holes and hot electrons for plasmon-promoted catalysis. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Irradiation of electronic components and circuits at the Portuguese Research Reactor: Lessons learned

    Energy Technology Data Exchange (ETDEWEB)

    Marques, J.G.; Ramos, A.R.; Fernandes, A.C.; Santos, J.P. [Centro de Ciencias e Tecnologias Nucleares, Instituto Superior Tecnico, Universidade de Lisboa, Estrada Nacional 10, 2695-066 Bobadela LRS (Portugal)

    2015-07-01

    The behavior of electronic components and circuits under radiation is a concern shared by the nuclear industry, the space community and the high-energy physics community. Standard commercial components are used as much as possible instead of radiation hard components, since they are easier to obtain and allow a significant reduction of costs. However, these standard components need to be tested in order to determine their radiation tolerance. The Portuguese Research Reactor (RPI) is a 1 MW pool-type reactor, operating since 1961. The irradiation of electronic components and circuits is one area where a 1 MW reactor can be competitive, since the fast neutron fluences required for testing are in most cases well below 10{sup 16} n/cm{sup 2}. A program was started in 1999 to test electronics components and circuits for the LHC facility at CERN, initially using a dedicated in-pool irradiation device and later a beam line with tailored neutron and gamma filters. Neutron filters are essential to reduce the intensity of the thermal neutron flux, which does not produce significant defects in electronic components but produces unwanted radiation from activation of contacts and packages of integrated circuits and also of the printed circuit boards. In irradiations performed within the line-of-sight of the core of a fission reactor there is simultaneous gamma radiation which complicates testing in some cases. Filters can be used to reduce its importance and separate testing with a pure gamma radiation source can contribute to clarify some irradiation results. Practice has shown the need to introduce several improvements to the procedures and facilities over the years. We will review improvements done in the following areas: - Optimization of neutron and gamma filters; - Dosimetry procedures in mixed neutron / gamma fields; - Determination of hardness parameter and 1 MeV-equivalent neutron fluence; - Temperature measurement and control during irradiation; - Follow-up of reactor

  17. 78 FR 34132 - Certain Portable Electronic Communications Devices, Including Mobile Phones and Components...

    Science.gov (United States)

    2013-06-06

    ... INTERNATIONAL TRADE COMMISSION [Docket No 2958] Certain Portable Electronic Communications Devices, Including Mobile Phones and Components Thereof; Correction to Notice of Receipt of Complaint; Solicitation... of complaint entitled Certain Portable Electronic Communications Devices, Including Mobile Phones and...

  18. Study of hot carrier relaxation in quantum wells by subpicosecond Raman scattering

    International Nuclear Information System (INIS)

    Kim, Dai-sik; Yu, P.Y.

    1990-03-01

    Relaxation of hot carriers excited by subpicosecond laser pulses has been studied by Raman scattering in GaAs/AlAs multiple quantum wells with well widths varying between 100 and 1000 Angstrom. The hot phonon population observed by Raman scattering is found to decrease with the well width despite the fact that the hot electron temperature remains constant. The results are explained in terms of confinement of both electrons and optical phonons in quantum wells

  19. Hot Spot Removal System: System description

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-09-01

    Hazardous wastes contaminated with radionuclides, chemicals, and explosives exist across the Department of Energy complex and need to be remediated due to environmental concerns. Currently, an opportunity is being developed to dramatically reduce remediation costs and to assist in the acceleration of schedules associated with these wastes by deploying a Hot Spot Removal System. Removing the hot spot from the waste site will remove risk driver(s) and enable another, more cost effective process/option/remedial alternative (i.e., capping) to be applied to the remainder of the site. The Hot Spot Removal System consists of a suite of technologies that will be utilized to locate and remove source terms. Components of the system can also be used in a variety of other cleanup activities. This Hot Spot Removal System Description document presents technologies that were considered for possible inclusion in the Hot Spot Removal System, technologies made available to the Hot Spot Removal System, industrial interest in the Hot Spot Removal System`s subsystems, the schedule required for the Hot Spot Removal System, the evaluation of the relevant technologies, and the recommendations for equipment and technologies as stated in the Plan section.

  20. Hot Spot Removal System: System description

    International Nuclear Information System (INIS)

    1997-09-01

    Hazardous wastes contaminated with radionuclides, chemicals, and explosives exist across the Department of Energy complex and need to be remediated due to environmental concerns. Currently, an opportunity is being developed to dramatically reduce remediation costs and to assist in the acceleration of schedules associated with these wastes by deploying a Hot Spot Removal System. Removing the hot spot from the waste site will remove risk driver(s) and enable another, more cost effective process/option/remedial alternative (i.e., capping) to be applied to the remainder of the site. The Hot Spot Removal System consists of a suite of technologies that will be utilized to locate and remove source terms. Components of the system can also be used in a variety of other cleanup activities. This Hot Spot Removal System Description document presents technologies that were considered for possible inclusion in the Hot Spot Removal System, technologies made available to the Hot Spot Removal System, industrial interest in the Hot Spot Removal System''s subsystems, the schedule required for the Hot Spot Removal System, the evaluation of the relevant technologies, and the recommendations for equipment and technologies as stated in the Plan section

  1. Printing Electronic Components from Copper-Infused Ink and Thermoplastic Mediums

    Science.gov (United States)

    Flowers, Patrick F.

    The demand for printable electronics has sharply increased in recent years and is projected to continue to rise. Unfortunately, electronic materials which are suitable for desired applications while being compatible with available printing techniques are still often lacking. This thesis addresses two such challenging areas. In the realm of two-dimensional ink-based printing of electronics, a major barrier to the realization of printable computers that can run programs is the lack of a solution-coatable non-volatile memory with performance metrics comparable to silicon-based devices. To address this deficiency, I developed a nonvolatile memory based on Cu-SiO2 core-shell nanowires that can be printed from solution and exhibits on-off ratios of 106, switching speeds of 50 ns, a low operating voltage of 2 V, and operates for at least 104 cycles without failure. Each of these metrics is similar to or better than Flash memory (the write speed is 20 times faster than Flash). Memory architectures based on the individual memory cells demonstrated here could enable the printing of the more complex, embedded computing devices that are expected to make up an internet of things. Recently, the exploration of three-dimensional printing techniques to fabricate electronic materials began. A suitable general-purpose conductive thermoplastic filament was not available, however. In this work I examine the current state of conductive thermoplastic filaments, including a newly-released highly conductive filament that my lab has produced which we call Electrifi. I focus on the use of dual-material fused filament fabrication (FFF) to 3D print electronic components (conductive traces, resistors, capacitors, inductors) and circuits (a fully-printed high-pass filter). The resistivity of traces printed from conductive thermoplastic filaments made with carbon-black, graphene, and copper as conductive fillers was found to be 12, 0.78, and 0.014 ohm cm, respectively, enabling the creation of

  2. YBCO hot-electron bolometers dedicated to THz detection and imaging: Embedding issues

    International Nuclear Information System (INIS)

    Aurino, M; Tuerer, I; Martinez, A; Gensbittel, A; Degardin, A F; Kreisler, A J

    2010-01-01

    High-T c hot-electron bolometers (HEB) are an interesting alternative to other superconducting heterodyne mixers in the terahertz frequency range because of low-cost cooling investment, ultra-wide instantaneous bandwidth and low intrinsic noise level, even at 80 K. A technological process to fabricate stacked yttrium-based (YBCO) / praseodymium-based (PBCO) ultra-thin films (in the 15 to 40 nm thickness range) etched to form 0.5 μm x 0.5 μm constrictions, elaborated on (100) MgO substrates, has been previously described. Ageing effects were also considered, with the consequence of increased electrical resistance, significant degradation of the regular THz response and no HEB mixing action. Electron and UV lithography steps are revisited here to realize HEB mixers based on nano-bridges covered by a log-periodic planar gold antenna, dedicated to the 1 to 7 THz range. Several measures have been attempted to reduce the conversion losses, mainly by considering the embedding issues related to the YBCO nano-bridge impedance matching to the antenna and the design of optimized intermediate frequency circuitry. Antenna simulations were performed and validated through experiments on scaled models at GHz frequencies. Electromagnetic coupling to the incoming radiation was also studied, including crosstalk between neighbour antennas forming a linear imaging array.

  3. The effect of introducing increased-reliability-risk electronic components into 3rd generation telecommunications systems

    International Nuclear Information System (INIS)

    Salmela, Olli

    2005-01-01

    In this paper, the dependability of 3rd generation telecommunications network systems is studied. Special attention is paid to a case where increased-reliability-risk electronic components are introduced to the system. The paper consists of three parts: First, the reliability data of four electronic components is considered. This includes statistical analysis of the reliability test data, thermo-mechanical finite element analysis of the printed wiring board structures, and based on those, a field reliability estimate of the components is constructed. Second, the component level reliability data is introduced into the network element reliability analysis. This is accomplished by using a reliability block diagram technique and Monte Carlo simulation of the network element. The end result of the second part is a reliability estimate of the network element with and without the high-risk component. Third, the whole 3rd generation network having multiple network elements is analyzed. In this part, the criticality of introducing high-risk electronic components into a 3rd generation telecommunications network is considered

  4. The effect of introducing increased-reliability-risk electronic components into 3rd generation telecommunications systems

    Energy Technology Data Exchange (ETDEWEB)

    Salmela, Olli [Nokia Networks, P.O. Box 301, 00045 Nokia Group (Finland)]. E-mail: olli.salmela@nokia.com

    2005-08-01

    In this paper, the dependability of 3rd generation telecommunications network systems is studied. Special attention is paid to a case where increased-reliability-risk electronic components are introduced to the system. The paper consists of three parts: First, the reliability data of four electronic components is considered. This includes statistical analysis of the reliability test data, thermo-mechanical finite element analysis of the printed wiring board structures, and based on those, a field reliability estimate of the components is constructed. Second, the component level reliability data is introduced into the network element reliability analysis. This is accomplished by using a reliability block diagram technique and Monte Carlo simulation of the network element. The end result of the second part is a reliability estimate of the network element with and without the high-risk component. Third, the whole 3rd generation network having multiple network elements is analyzed. In this part, the criticality of introducing high-risk electronic components into a 3rd generation telecommunications network is considered.

  5. Hot electron light emission in gallium arsenide/aluminium(x) gallium(1-x) arsenic heterostructures

    Science.gov (United States)

    Teke, Ali

    In this thesis we have demonstrated the operation of a novel tunable wavelength surface light emitting device. The device is based on a p-GaAs, and n-Ga1- xAlxAs heterojunction containing an inversion layer on the p- side, and GaAs quantum wells on the n- side, and, is referred to as HELLISH-2 (Hot Electron Light Emitting and Lasing in Semiconductor Heterostructure-Type 2). The devices utilise hot electron longitudinal transport and, therefore, light emission is independent of the polarity of the applied voltage. The wavelength of the emitted light can be tuned with the applied bias from GaAs band-to-band transition in the inversion layer to e1-hh1 transition in the quantum wells. In this work tunable means that the device can be operated at either single or multiple wavelength emission. The operation of the device requires only two diffused in point contacts. In this project four HELLISH-2 samples coded as ES1, ES2, ES6 and QT919 have been studied. First three samples were grown by MBE and the last one was grown by MOVPE techniques. ES1 was designed for single and double wavelength operation. ES2 was a control sample used to compare our results with previous work on HELLISH-2 and ES6 was designed for single, double and triple wavelength operation. Theoretical modelling of the device operation was carried out and compared with the experimental results. HELLISH-2 structure was optimised for low threshold and high efficiency operation as based on our model calculations. The last sample QT919 has been designed as an optimised device for single and double wavelength operation like ES1. HELLISH-2 has a number of advantages over the conventional light emitters, resulting in some possible applications, such as light logic gates and wavelength division multiplexing in optoelectronic.

  6. Hot springs in Hokuriku District

    Energy Technology Data Exchange (ETDEWEB)

    Sato, K. (Hot Springs Research Center, Japan)

    1971-01-01

    In the Hokuriku district including Toyama, Ishikawa, and Fukui Prefectures, hot springs of more than 25/sup 0/C were investigated. In the Toyama Prefecture, there are 14 hot springs which are located in an area from the Kurobe River to the Tateyama volcano and in the mountainous area in the southwest. In Ishikawa Prefecture there are 16 hot springs scattered in Hakusan and its vicinity, the Kaga mountains, and in the Noto peninsula. In northern Fukui Prefecture there are seven hot springs. The hot springs in Shirakawa in Gifu Prefecture are characterized as acid springs producing exhalations and H/sub 2/S. These are attributed to the Quaternary volcanoes. The hot springs of Wakura, Katayamazu, and Awara in Ishikawa Prefecture are characterized by a high Cl content which is related to Tertiary andesite. The hot springs of Daishoji, Yamanaka, Yamashiro, Kuritsu, Tatsunokuchi, Yuwaku, and Yunotani are characterized by a low HCO/sub 3/ content. The Ca and SO/sub 4/ content decreases from east to west, and the Na and Cl content increases from west to east. These fluctuations are related to the Tertiary tuff and rhyolite. The hot springs of Kuronagi, Kinshu, and Babadani, located along the Kurobe River are characterized by low levels of dissolved components and high CO/sub 2/ and HCO/sub 3/ content. These trends are related to late Paleozoic granite. Hot springs resources are considered to be connected to geothermal resources. Ten tables, graphs, and maps are provided.

  7. 78 FR 56737 - Certain Portable Electronic Communications Devices, Including Mobile Phones and Components...

    Science.gov (United States)

    2013-09-13

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-885] Certain Portable Electronic Communications Devices, Including Mobile Phones and Components Thereof; Commission Determination Not To Review an... on the Commission's electronic docket (EDIS) at http://edis.usitc.gov . Hearing-impaired persons are...

  8. 78 FR 49764 - Certain Portable Electronic Communications Devices, Including Mobile Phones and Components...

    Science.gov (United States)

    2013-08-15

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-885] Certain Portable Electronic Communications Devices, Including Mobile Phones and Components Thereof; Commission Determination Not To Review n... for this investigation may be viewed on the Commission's electronic docket (EDIS) at http://edis.usitc...

  9. 78 FR 72712 - Certain Portable Electronic Communications Devices, Including Mobile Phones and Components...

    Science.gov (United States)

    2013-12-03

    ... INTERNATIONAL TRADE COMMISSION [Investigation No. 337-TA-885] Certain Portable Electronic Communications Devices, Including Mobile Phones and Components Thereof; Commission Determination Not To Review an... this investigation may be viewed on the Commission's electronic docket (EDIS) at http://edis.usitc.gov...

  10. Microstructural Architecture, Microstructures, and Mechanical Properties for a Nickel-Base Superalloy Fabricated by Electron Beam Melting

    Science.gov (United States)

    Murr, L. E.; Martinez, E.; Gaytan, S. M.; Ramirez, D. A.; Machado, B. I.; Shindo, P. W.; Martinez, J. L.; Medina, F.; Wooten, J.; Ciscel, D.; Ackelid, U.; Wicker, R. B.

    2011-11-01

    Microstructures and a microstructural, columnar architecture as well as mechanical behavior of as-fabricated and processed INCONEL alloy 625 components produced by additive manufacturing using electron beam melting (EBM) of prealloyed precursor powder are examined in this study. As-fabricated and hot-isostatically pressed ("hipped") [at 1393 K (1120 °C)] cylinders examined by optical metallography (OM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive (X-ray) spectrometry (EDS), and X-ray diffraction (XRD) exhibited an initial EBM-developed γ″ (bct) Ni3Nb precipitate platelet columnar architecture within columnar [200] textured γ (fcc) Ni-Cr grains aligned in the cylinder axis, parallel to the EBM build direction. Upon annealing at 1393 K (1120 °C) (hot-isostatic press (HIP)), these precipitate columns dissolve and the columnar, γ, grains recrystallized forming generally equiaxed grains (with coherent {111} annealing twins), containing NbCr2 laves precipitates. Microindentation hardnesses decreased from 2.7 to 2.2 GPa following hot-isostatic pressing ("hipping"), and the corresponding engineering (0.2 pct) offset yield stress decreased from 0.41 to 0.33 GPa, while the UTS increased from 0.75 to 0.77 GPa. However, the corresponding elongation increased from 44 to 69 pct for the hipped components.

  11. Design of all-optical, hot-electron current-direction-switching device based on geometrical asymmetry.

    Science.gov (United States)

    Kumarasinghe, Chathurangi S; Premaratne, Malin; Gunapala, Sarath D; Agrawal, Govind P

    2016-02-18

    We propose a nano-scale current-direction-switching device(CDSD) that operates based on the novel phenomenon of geometrical asymmetry between two hot-electron generating plasmonic nanostructures. The proposed device is easy to fabricate and economical to develop compared to most other existing designs. It also has the ability to function without external wiring in nano or molecular circuitry since it is powered and controlled optically. We consider a such CDSD made of two dissimilar nanorods separated by a thin but finite potential barrier and theoretically derive the frequency-dependent electron/current flow rate. Our analysis takes in to account the quantum dynamics of electrons inside the nanorods under a periodic optical perturbation that are confined by nanorod boundaries, modelled as finite cylindrical potential wells. The influence of design parameters, such as geometric difference between the two nanorods, their volumes and the barrier width on quality parameters such as frequency-sensitivity of the current flow direction, magnitude of the current flow, positive to negative current ratio, and the energy conversion efficiency is discussed by considering a device made of Ag/TiO2/Ag. Theoretical insight and design guidelines presented here are useful for customizing our proposed CDSD for applications such as self-powered logic gates, power supplies, and sensors.

  12. Performance of nickel base superalloy components in gas turbines

    DEFF Research Database (Denmark)

    Dahl, Kristian Vinter

    2006-01-01

    The topic of this thesis is the microstructural behaviour of hot section components in the industrial gas turbine......The topic of this thesis is the microstructural behaviour of hot section components in the industrial gas turbine...

  13. Distinct Rayleigh scattering from hot spot mutant p53 proteins reveals cancer cells.

    Science.gov (United States)

    Jun, Ho Joon; Nguyen, Anh H; Kim, Yeul Hong; Park, Kyong Hwa; Kim, Doyoun; Kim, Kyeong Kyu; Sim, Sang Jun

    2014-07-23

    The scattering of light redirects and resonances when an electromagnetic wave interacts with electrons orbits in the hot spot core protein and oscillated electron of the gold nanoparticles (AuNP). This report demonstrates convincingly that resonant Rayleigh scattering generated from hot spot mutant p53 proteins is correspondence to cancer cells. Hot spot mutants have unique local electron density changes that affect specificity of DNA binding affinity compared with wild types. Rayleigh scattering changes introduced by hot-spot mutations were monitored by localized surface plasmon resonance (LSPR) shift changes. The LSPR λmax shift for hot-spot mutants ranged from 1.7 to 4.2 nm for mouse samples and from 0.64 nm to 2.66 nm for human samples, compared to 9.6 nm and 15 nm for wild type and mouse and human proteins, respectively with a detection sensitivity of p53 concentration at 17.9 nM. It is interesting that hot-spot mutants, which affect only interaction with DNA, launches affinitive changes as considerable as wild types. These changes propose that hot-spot mutants p53 proteins can be easily detected by local electron density alterations that disturbs the specificity of DNA binding of p53 core domain on the surface of the DNA probed-nanoplasmonic sensor. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Direct observation of the growth of voids in multifilamentary superconducting materials via hot stage scanning electron microscopy

    International Nuclear Information System (INIS)

    Wang, J.L.F.; Holthuis, J.T.; Pickus, M.R.; Lindberg, R.W.

    1978-11-01

    The need for large high field magnetic devices has focused attention on multifilamentary superconductors based on A15 compounds such as Nb 3 Sn. The commercial bronze process for fabricating multifilamentary superconducting Nb 3 Sn wires was developed. A major problem is strain sensitivity when long reaction times are employed. An improved hot stage for the scanning electron microscope was constructed to study the formation of the A15 phase by solid state diffusion. The nucleation and growth of voids near the interface of the A15 phase (Nb 3 Sn) and matrix were observed, monitored, and recorded on video tape. Successive layers of material heated in the hot stage were subsequently removed and the new surfaces were re-examined, using SEM-EDX and optical microscopy, to confirm the fact that the observed porosity was indeed a bulk rather than a surface phenomenon. These voids are considered to be a primary cause for degrading the mechanical, thermal and superconducting properties

  15. 27 CFR 73.11 - What are the required components and controls for acceptable electronic signatures?

    Science.gov (United States)

    2010-04-01

    ... components and controls for acceptable electronic signatures? 73.11 Section 73.11 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY (CONTINUED) PROCEDURES AND PRACTICES ELECTRONIC SIGNATURES; ELECTRONIC SUBMISSION OF FORMS Electronic Signatures § 73.11...

  16. Hot-electron bolometer terahertz mixers for the Herschel Space Observatory.

    Science.gov (United States)

    Cherednichenko, Sergey; Drakinskiy, Vladimir; Berg, Therese; Khosropanah, Pourya; Kollberg, Erik

    2008-03-01

    We report on low noise terahertz mixers (1.4-1.9 THz) developed for the heterodyne spectrometer onboard the Herschel Space Observatory. The mixers employ double slot antenna integrated superconducting hot-electron bolometers (HEBs) made of thin NbN films. The mixer performance was characterized in terms of detection sensitivity across the entire rf band by using a Fourier transform spectrometer (from 0.5 to 2.5 THz, with 30 GHz resolution) and also by measuring the mixer noise temperature at a limited number of discrete frequencies. The lowest mixer noise temperature recorded was 750 K [double sideband (DSB)] at 1.6 THz and 950 K DSB at 1.9 THz local oscillator (LO) frequencies. Averaged across the intermediate frequency band of 2.4-4.8 GHz, the mixer noise temperature was 1100 K DSB at 1.6 THz and 1450 K DSB at 1.9 THz LO frequencies. The HEB heterodyne receiver stability has been analyzed and compared to the HEB stability in the direct detection mode. The optimal local oscillator power was determined and found to be in a 200-500 nW range.

  17. The effect of cushion-ram pulsation on hot stamping

    Science.gov (United States)

    Landgrebe, Dirk; Rautenstrauch, Anja; Kunke, Andreas; Polster, Stefan; Kriechenbauer, Sebastian; Mauermann, Reinhard

    2016-10-01

    Hot stamping is an important technology for manufacturing high-strength components. This technology offers the possibility to achieve significant weight reductions. In this study, cushion-ram pulsation (CRP), a new technology for hot stamping on servo-screw presses, was investigated and applied for hot stamping. Compared to a conventional process, the tests yielded a significantly higher drawing depth. In this paper, the CRP technology and the first test results with hot stamping were described in comparison to the conventional process.

  18. Influence of laser induced hot electrons on the threshold for shock ignition of fusion reactions

    Energy Technology Data Exchange (ETDEWEB)

    Colaïtis, A.; Ribeyre, X.; Le Bel, E.; Duchateau, G.; Nicolaï, Ph.; Tikhonchuk, V. [Centre Lasers Intenses et Applications, Université de Bordeaux - CNRS - CEA, UMR 5107,351 Cours de la Libération, 33400 Talence (France)

    2016-07-15

    The effects of Hot Electrons (HEs) generated by the nonlinear Laser-Plasma Interaction (LPI) on the dynamics of Shock Ignition Inertial Confinement Fusion targets are investigated. The coupling between the laser beam, plasma dynamics and hot electron generation and propagation is described with a radiative hydrodynamics code using an inline model based on Paraxial Complex Geometrical Optics [Colaïtis et al., Phys. Rev. E 92, 041101 (2015)]. Two targets are considered: the pure-DT HiPER target and a CH-DT design with baseline spike powers of the order of 200–300 TW. In both cases, accounting for the LPI-generated HEs leads to non-igniting targets when using the baseline spike powers. While HEs are found to increase the ignitor shock pressure, they also preheat the bulk of the imploding shell, notably causing its expansion and contamination of the hotspot with the dense shell material before the time of shock convergence. The associated increase in hotspot mass (i) increases the ignitor shock pressure required to ignite the fusion reactions and (ii) significantly increases the power losses through Bremsstrahlung X-ray radiation, thus rapidly cooling the hotspot. These effects are less prominent for the CH-DT target where the plastic ablator shields the lower energy LPI-HE spectrum. Simulations using higher laser spike powers of 500 TW suggest that the CH-DT capsule marginally ignites, with an ignition window width significantly smaller than without LPI-HEs, and with three quarters of the baseline target yield. The latter effect arises from the relation between the shock launching time and the shell areal density, which becomes relevant in presence of a LPI-HE preheating.

  19. Trapping in GaN-based metal-insulator-semiconductor transistors: Role of high drain bias and hot electrons

    Energy Technology Data Exchange (ETDEWEB)

    Meneghini, M., E-mail: matteo.meneghini@dei.unipd.it; Bisi, D.; Meneghesso, G.; Zanoni, E. [Department of Information Engineering, University of Padova, via Gradenigo 6/B, 35131 Padova (Italy); Marcon, D.; Stoffels, S.; Van Hove, M.; Wu, T.-L.; Decoutere, S. [IMEC, Kapeldreef 75, 3001 Heverlee (Belgium)

    2014-04-07

    This paper describes an extensive analysis of the role of off-state and semi-on state bias in inducing the trapping in GaN-based power High Electron Mobility Transistors. The study is based on combined pulsed characterization and on-resistance transient measurements. We demonstrate that—by changing the quiescent bias point from the off-state to the semi-on state—it is possible to separately analyze two relevant trapping mechanisms: (i) the trapping of electrons in the gate-drain access region, activated by the exposure to high drain bias in the off-state; (ii) the trapping of hot-electrons within the AlGaN barrier or the gate insulator, which occurs when the devices are operated in the semi-on state. The dependence of these two mechanisms on the bias conditions and on temperature, and the properties (activation energy and cross section) of the related traps are described in the text.

  20. Extracting hot carriers from photoexcited semiconductor nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaoyang

    2014-12-10

    This research program addresses a fundamental question related to the use of nanomaterials in solar energy -- namely, whether semiconductor nanocrystals (NCs) can help surpass the efficiency limits, the so-called “Shockley-Queisser” limit, in conventional solar cells. In these cells, absorption of photons with energies above the semiconductor bandgap generates “hot” charge carriers that quickly “cool” to the band edges before they can be utilized to do work; this sets the solar cell efficiency at a limit of ~31%. If instead, all of the energy of the hot carriers could be captured, solar-to-electric power conversion efficiencies could be increased, theoretically, to as high as 66%. A potential route to capture this energy is to utilize semiconductor nanocrystals. In these materials, the quasi-continuous conduction and valence bands of the bulk semiconductor become discretized due to confinement of the charge carriers. Consequently, the energy spacing between the electronic levels can be much larger than the highest phonon frequency of the lattice, creating a “phonon bottleneck” wherein hot-carrier relaxation is possible via slower multiphonon emission. For example, hot-electron lifetimes as long as ~1 ns have been observed in NCs grown by molecular beam epitaxy. In colloidal NCs, long lifetimes have been demonstrated through careful design of the nanocrystal interfaces. Due to their ability to slow electronic relaxation, semiconductor NCs can in principle enable extraction of hot carriers before they cool to the band edges, leading to more efficient solar cells.

  1. Component-Level Electronic-Assembly Repair (CLEAR) System Architecture

    Science.gov (United States)

    Oeftering, Richard C.; Bradish, Martin A.; Juergens, Jeffrey R.; Lewis, Michael J.; Vrnak, Daniel R.

    2011-01-01

    This document captures the system architecture for a Component-Level Electronic-Assembly Repair (CLEAR) capability needed for electronics maintenance and repair of the Constellation Program (CxP). CLEAR is intended to improve flight system supportability and reduce the mass of spares required to maintain the electronics of human rated spacecraft on long duration missions. By necessity it allows the crew to make repairs that would otherwise be performed by Earth based repair depots. Because of practical knowledge and skill limitations of small spaceflight crews they must be augmented by Earth based support crews and automated repair equipment. This system architecture covers the complete system from ground-user to flight hardware and flight crew and defines an Earth segment and a Space segment. The Earth Segment involves database management, operational planning, and remote equipment programming and validation processes. The Space Segment involves the automated diagnostic, test and repair equipment required for a complete repair process. This document defines three major subsystems including, tele-operations that links the flight hardware to ground support, highly reconfigurable diagnostics and test instruments, and a CLEAR Repair Apparatus that automates the physical repair process.

  2. Axions as hot and cold dark matter

    International Nuclear Information System (INIS)

    Jeong, Kwang Sik; Kawasaki, Masahiro; Tokyo Univ., Kashiwa; Takahashi, Fuminobu; Tokyo Univ., Kashiwa

    2013-10-01

    The presence of a hot dark matter component has been hinted at 3σ by a combination of the results from different cosmological observations. We examine a possibility that pseudo Nambu- Goldstone bosons account for both hot and cold dark matter components. We show that the QCD axions can do the job for the axion decay constant f a 10 ) GeV, if they are produced by the saxion decay and the domain wall annihilation. We also investigate the cases of thermal QCD axions, pseudo Nambu-Goldstone bosons coupled to the standard model sector through the Higgs portal, and axions produced by modulus decay.

  3. Axions as hot and cold dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Kwang Sik [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Kawasaki, Masahiro [Tokyo Univ., Kashiwa (Japan). Inst. for Cosmic Ray Research; Tokyo Univ., Kashiwa (Japan). Kavli IPMU, TODIAS; Takahashi, Fuminobu [Tohoku Univ., Sendai (Japan). Dept. of Physics; Tokyo Univ., Kashiwa (Japan). Kavli IPMU, TODIAS

    2013-10-15

    The presence of a hot dark matter component has been hinted at 3{sigma} by a combination of the results from different cosmological observations. We examine a possibility that pseudo Nambu- Goldstone bosons account for both hot and cold dark matter components. We show that the QCD axions can do the job for the axion decay constant f{sub a}

  4. Physics of dust grains in hot gas

    International Nuclear Information System (INIS)

    Draine, B.T.; Salpeter, E.E.

    1979-01-01

    Charging of dust grains in hot (10 4 --10 9 K) plasma is studied, including photoelectron and secondary electron emission, field emission, and transmission of electrons and ions through the grain; resulting grain potentials are (for T > or approx. = 10 5 K) considerably smaller in magnitude than found by Burke and Silk. Even so, large electrostatic stresses can cause ion field emission and rapid destruction of small grains in very hot gas. Rapid rotation can also disrupt small grains, but damping (by microwave emission) usually limits the centrifugal stress to acceptable values for plasma densities n/sub H/ -3 . Sputtering rates are estimated for grains in hot gas, based upon a semiempirical fit to experimental data. Predicted sputtering rates for possible grain constituents are similar to estimates by Barlow, but in some cases differ significantly. Useful approximation formulae are given for the drag forces acting on a grain with arbitrary Mach number

  5. Nonlinear electron acoustic structures generated on the high-potential side of a double layer

    Directory of Open Access Journals (Sweden)

    R. Pottelette

    2009-04-01

    Full Text Available High-time resolution measurements of the electron distribution function performed in the auroral upward current region reveals a large asymmetry between the low- and high-potential sides of a double-layer. The latter side is characterized by a large enhancement of a locally trapped electron population which corresponds to a significant part (~up to 30% of the total electron density. As compared to the background hot electron population, this trapped component has a very cold temperature in the direction parallel to the static magnetic field. Accordingly, the differential drift between the trapped and background hot electron populations generates high frequency electron acoustic waves in a direction quasi-parallel to the magnetic field. The density of the trapped electron population can be deduced from the frequency where the electron acoustic spectrum maximizes. In the auroral midcavity region, the electron acoustic waves may be modulated by an additional turbulence generated in the ion acoustic range thanks to the presence of a pre-accelerated ion beam located on the high-potential side of the double layer. Electron holes characterized by bipolar pulses in the electric field are sometimes detected in correlation with these electron acoustic wave packets.

  6. Mechanical design and testing of a hot-gas turbine on a test facility

    International Nuclear Information System (INIS)

    Staude, R.

    1981-01-01

    Advanced calculation methods and specific solutions for any particular problem are basic requirements for the mechanical design of hot-gas components for gas turbines. The mechanical design contributes a great deal to the smooth running and operational reliability and thus to the quality of the machine. By reference to an expander, the present paper discusses the strength of hot components, such as the casing and the rotor, for both stationary and transient temperature distribution. Mechanical testing under hot-gas conditions fully confirmed the reliability of the rating and design of the hot-gas turbines supplied by M:A.N.-GHH STERKRADE. (orig.) [de

  7. Numerical simulation of runaway electron effect on Plasma Facing Components

    International Nuclear Information System (INIS)

    Ezato, Koichiro; Suzuki, Satoshi; Akiba, Masato; Kunugi, Tomoaki

    1998-07-01

    The runaway electron effects on Plasma Facing Components (PFCs) are studied by the numerical analyses. The present study is the first investigation of time-dependent thermal response of PFCs caused by runaway electron impact. For this purpose, we developed a new integrated numerical code, which consists of the Monte Carlo code for the coupled electrons and photons transport analysis and the finite element code for the thermo-mechanical analysis. In this code, we apply the practical incident parameters and distribution of runaway electrons recently proposed by S. Putvinski, which can express the time-dependent behavior of runaway electrons impact. The incident parameters of electrons in this study are the energy density ranging from 10 to 75 MJ/m 2 , the average electrons' energy of 12.5 MeV, the incident angle of 0.01deg and the characteristic time constant for decay of runaway electrons event of 0.15sec. The numerical results showed that the divertor with CFC (Carbon-Fiber-Composite) armor did not suffer serious damage. On the other hand, maximum temperatures at the surface of the divertor with tungsten armor and the first wall with beryllium armor exceed the melting point in case of the incident energy density of 20 and 50 MJ/m 2 . Within the range of the incident condition of runaway electrons, the cooling pipe of each PFCs can be prevented from the melting or burn-out caused by runaway electrons impact, which is one of the possible consequences of runaway electrons event so far. (author)

  8. Scanning electron microscopy and electron probe microanalyses of the crystalline components of human and animal dental calculi

    International Nuclear Information System (INIS)

    LeGeros, R.Z.; Orly, I.; LeGeros, J.P.; Gomez, C.; Kazimiroff, J.; Tarpley, T.; Kerebel, B.

    1988-01-01

    A review of the use of scanning electron microscopy (SEM) and electron probe microanalyses in the study of dental calculus showed that such studies provided confirmatory and supplementary data on the morphological features of human dental calculi but gave only limited information on the identity of the crystalline or inorganic components. This study aimed to explore the potential of combined SEM and microanalyses in the identification of the crystalline components of the human and animal dental calculi. Human and animal calculi were analyzed. Identification of the crystalline components were made based on the combined information of the morphology (SEM) and Ca/P molar ratios of the crystals with the morphology and Ca/P molar ratio of synthetic calcium phosphates (brushite or DCPD; octacalcium phosphate, OCP; Mg-substituted whitlockite, beta-TCMP; CO 3 -substituted apatite, (CHA); and calcite. SEM showed similarities in morphological features of human and animal dental calculi but differences in the forms of crystals present. Microanalyses and crystal morphology data suggested the presence of CaCO 3 (calcite) and CHA in the animal (cat, dog, tiger) and of OCP, beta-TCMP and CHA in human dental calculi. X-ray diffraction and infrared (IR) absorption analyses confirmed these results. This exploratory study demonstrated that by taking into consideration what is known about the crystalline components of human and animal dental calculi, combined SEM and microanalyses can provide qualitative identification

  9. Tracking and Control of Gas Turbine Engine Component Damage/Life

    Science.gov (United States)

    Jaw, Link C.; Wu, Dong N.; Bryg, David J.

    2003-01-01

    This paper describes damage mechanisms and the methods of controlling damages to extend the on-wing life of critical gas turbine engine components. Particularly, two types of damage mechanisms are discussed: creep/rupture and thermo-mechanical fatigue. To control these damages and extend the life of engine hot-section components, we have investigated two methodologies to be implemented as additional control logic for the on-board electronic control unit. This new logic, the life-extending control (LEC), interacts with the engine control and monitoring unit and modifies the fuel flow to reduce component damages in a flight mission. The LEC methodologies were demonstrated in a real-time, hardware-in-the-loop simulation. The results show that LEC is not only a new paradigm for engine control design, but also a promising technology for extending the service life of engine components, hence reducing the life cycle cost of the engine.

  10. Analysis of electron cyclotron emission spectra of high electron temperature, supershot plasmas in TFTR

    International Nuclear Information System (INIS)

    Taylor, G.; Arunasalam, V.; Efthimion, P.C.; Grek, B.

    1993-01-01

    A primary objective of the TFTR program since 1986 has been the study and optimization of deuterium Supershot plasmas. These plasmas are predominantly heated by 90-110 keV neutral deuterium beams (P NBI /P OH >30), central ion temperatures are ∝30 keV and central electron temperatures from ECE (T ECE ) often exceed 10 keV. Central electron temperature data measured with a TV Thomson scattering (TVTS) system (T TVTS ) during the period 1987-1990 have been compared with data from three different ECE instruments on TFTR. Although T ECE ∝T TVTS for temperatures below 6 keV, there is a systematically increasing disagreement at higher electron temperatures, with T ECE ∝1.2 T TVTS for T TVTS in the range 9-10 keV. Recent theoretical work on the ECE radiation temperature of non-equilibrium plasmas indicates that for a bi-Maxwellian electron velocity distribution with a ratio of tail to bulk electron density η, a bulk temperature T b , and a hot tail temperature T h , the perpendicular ECE radiation temperature is given by T ECE ∝T b {1+η(T h /T b )}, for η ECE would be enhanced over T TVTS by a factor which depends on η and T h . This paper investigates whether the discrepancy between T TVTS and T ECE seen in TFTR Supershots at high electron temperatures is due to the presence of a hot electron tail component. The extraordinary mode ECE spectrum at the second, third and fourth harmonics is measured on the horizontal midplane by an absolutely calibrated ECE Michelson interferometer. This ECE spectrum is compared with the output from a time-independent transport code with relativistic opacity which solves the three-dimensional ECE radiation transport in a toroidally symmetric, two-dimensional geometry and uses measured electron density and temperature profiles from the TVTS system. (orig.)

  11. The Hot ISM of Normal Galaxies

    Science.gov (United States)

    Fabbiano, Giuseppina

    1999-01-01

    X-ray observations of galaxies have shown the presence of hot ISM and gaseous halos. The most spectacular examples am in early-type galaxies (E and S0), and in galaxies hosting intense starforming regions. This talk will review the observational evidence and highlight the outstanding issues in our understanding of this gaseous component, with emphasis on our present understanding of the chemical composition of these hot halos. It will address how Chandra, XMM, and future X-ray missions can address these studies.

  12. Effects of electron beam irradiation combined with hot water immersion treatment for shelf life extension of bananas

    International Nuclear Information System (INIS)

    Russly Abdul Rahman

    1996-01-01

    A study of the effects of minimal processing treatments, both individually or in combinations, was carried out in order to extend the shelf life and to improve the quality of bananas. Pre climacteric bananas at light full three-quarter grade, were either treated with hot water immersion for 1-30 min at 45-55 degree C, or irradiated with electron beams (2.0 MeV, Van de Graaff accelerator), to a dose of 0.1-1.5 kGy. All fruit was stored at 21 ± 1 degree C and relative humidity of 85-95 %. There was no significant delay in ripening of fruit treated with hot water immersion at the above temperatures. Some damage to fruit particularly peel scalding at ends occurred at the higher temperatures (>50 degree C). The 50 degree C, 5 minutes immersion was selected for further study. Irradiation to 0.1-0.3 kGy delayed the ripening (up to 3 days) without affecting fruit quality. Doses greater than 0.4 kGy resulted in extensive discoloration and fruit splitting. No significant differences could be detected organoleptically between bananas irradiated at 0.15 kGy and the control. Results of the physico-chemical attributes of the bananas were reported for fruits at colour stage 5 and after 10 and 15 days of storage. The combination treatment of hot water immersion and irradiation at the above settings further extended the shelf life of the banana fruits

  13. Estimation method for volumes of hot spots created by heavy ions

    International Nuclear Information System (INIS)

    Kanno, Ikuo; Kanazawa, Satoshi; Kajii, Yuji

    1999-01-01

    As a ratio of volumes of hot spots to cones, which have the same lengths and bottom radii with the ones of hot spots, a simple and convenient method for estimating the volumes of hot spots is described. This calculation method is useful for the study of damage producing mechanism in hot spots, and is also convenient for the estimation of the electron-hole densities in plasma columns created by heavy ions in semiconductor detectors. (author)

  14. Imaging Cytoskeleton Components by Electron Microscopy.

    Science.gov (United States)

    Svitkina, Tatyana

    2016-01-01

    The cytoskeleton is a complex of detergent-insoluble components of the cytoplasm playing critical roles in cell motility, shape generation, and mechanical properties of a cell. Fibrillar polymers-actin filaments, microtubules, and intermediate filaments-are major constituents of the cytoskeleton, which constantly change their organization during cellular activities. The actin cytoskeleton is especially polymorphic, as actin filaments can form multiple higher order assemblies performing different functions. Structural information about cytoskeleton organization is critical for understanding its functions and mechanisms underlying various forms of cellular activity. Because of the nanometer-scale thickness of cytoskeletal fibers, electron microscopy (EM) is a key tool to determine the structure of the cytoskeleton. This article describes application of rotary shadowing (or metal replica) EM for visualization of the cytoskeleton. The procedure is applicable to thin cultured cells growing on glass coverslips and consists of detergent extraction of cells to expose their cytoskeleton, chemical fixation to provide stability, ethanol dehydration and critical point drying to preserve three-dimensionality, rotary shadowing with platinum to create contrast, and carbon coating to stabilize replicas. This technique provides easily interpretable three-dimensional images, in which individual cytoskeletal fibers are clearly resolved, and individual proteins can be identified by immunogold labeling. More importantly, replica EM is easily compatible with live cell imaging, so that one can correlate the dynamics of a cell or its components, e.g., expressed fluorescent proteins, with high resolution structural organization of the cytoskeleton in the same cell.

  15. Collaborative Research Centre 694 “Integration of electronic components into mobile systems”-Motivation and survey

    Science.gov (United States)

    Weckenmann, Albert; Schmidt, Lorenz-Peter; Bookjans, Martin

    Within the collaborative research centre 694 'Integration of electronic components into mobile systems' intelligent mechatronic systems are explored for application at the place of action. Especially in the automotive sector highest requirements on system safety are combined with an enormous importance of the production for the whole national economy. Therefore the collaborative research centre is led by the vision to integrate electronic components in sensors and actors of mobile systems. About 30 scientists at nine participating academic and non-academic institutions in Erlangen explore mechatronic solutions for the requirements on manufacturing processes, electronic systems and quality management techniques within the car of the future.

  16. 21 CFR 175.230 - Hot-melt strippable food coatings.

    Science.gov (United States)

    2010-04-01

    ..., white For use only as a component of hot-melt strippable food coatings applied to frozen meats and... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Hot-melt strippable food coatings. 175.230 Section 175.230 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

  17. Optically stimulated luminescence in electronic components for emergency dosimetry

    International Nuclear Information System (INIS)

    Geber-Bergstrand, T.; Bernhardsson, C.; Mattsson, S.; Raeaef, C.L.

    2015-01-01

    Document available in abstract form only. Full text of publication follows: Accidents and, luckily more rarely, attacks involving nuclear or radiological material do occur from time to time. A very possible consequence of an accident or attack of this kind is that nearby people might be exposed to ionising radiation. Since these types of exposure situations, unlike the ones occurring in medicine, are unplanned, there are no radiation-monitoring data available. For several reasons, it is nevertheless of value to find out the dose that these people have received. The first and most urgent reason is after-the-event triage, to be able to carry out proper medical treatments and also to focus the available medical assets to the persons needing it the most. This is where different retrospective dosimetry techniques, such as luminescence, can be employed. Various electronic components from mobile phones and other portable devices have been studied using optically stimulated luminescence for their potential use in retrospective dosimetry. Previous investigations have been performed in laboratory conditions and have showed very promising properties for emergency dosimetry. In this study, the more practical parts of using electronic components in retrospective dosimetry have been considered. In a triage situation, one of the key parameters to consider is time; thus, effort has been made to speed up the readout procedure, yet without the loss of too much accuracy. (authors)

  18. Nonlinear waves in electron-positron-ion plasmas including charge separation

    Science.gov (United States)

    Mugemana, A.; Moolla, S.; Lazarus, I. J.

    2017-02-01

    Nonlinear low-frequency electrostatic waves in a magnetized, three-component plasma consisting of hot electrons, hot positrons and warm ions have been investigated. The electrons and positrons are assumed to have Boltzmann density distributions while the motion of the ions are governed by fluid equations. The system is closed with the Poisson equation. This set of equations is numerically solved for the electric field. The effects of the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle are investigated. It is shown that depending on the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle, the numerical solutions exhibit waveforms that are sinusoidal, sawtooth and spiky. The introduction of the Poisson equation increased the Mach number required to generate the waveforms but the driving electric field E 0 was reduced. The results are compared with satellite observations.

  19. The critical components of an electronic care plan tool for primary care: an exploratory qualitative study

    Directory of Open Access Journals (Sweden)

    Lisa Rotenstein

    2016-07-01

    Full Text Available Background A critical need exists for effective electronic tools that facilitate multidisciplinary care for complex patients in patient-centered medical homes. Objective To identify the essential components of a primary care (PC based electronic care plan (ECP tool that facilitates coordination of care for complex patients. Methods Three focus groups and nine semi-structured interviews were conducted at an academic PC practice in order to identify the ideal components of an ECP. Results Critical components of an ECP identified included: 1 patient background information, including patient demographics, care team member designation and key patient contacts, 2 user- and patient-centric task management functionalities, 3 a summary of a patient’s care needs linked to the responsible member of the care team and 4 integration with the electronic medical record. We then designed an ECP mockup incorporating these components. Conclusion Our investigation identified key principles that healthcare software developers can integrate into PC and patient-centered ECP tools.

  20. HOT AEROSOL FIRE EXTINGUISHING AGENTS AND THE ASSOCIATED TECHNOLOGIES: A REVIEW

    Directory of Open Access Journals (Sweden)

    Xiaotian Zhang

    2015-09-01

    Full Text Available AbstractSince the phase out of Halon extinguishers in the 1980s, hot aerosol fire suppression technology has gained much attention. Unlike traditional inert gas, foam, water mist and Halon fire suppression agents, hot aerosol fire extinguishing agents do not need to be driven out by pressurized gases and can extinguish class A, B, C, D and K fires at 30 to 200 g/m3. Generally, hot aerosol fire extinguishing technology has developed from a generation I oil tank suppression system to a generation III strontium salt based S-type system. S-type hot aerosol fire extinguishing technology greatly solves the corrosion problem of electrical devices and electronics compared to potassium salt based generation I & II hot aerosol fire extinguishing technology. As substitutes for Halon agents, the ODP and GWP values of hot fire extinguishing aerosols are nearly zero, but those fine aerosol particles can cause adverse health effects once inhaled by human. As for configurations of hot aerosol fire extinguishing devices, fixed or portable cylindrical canisters are the most common among generation II & III hot aerosol fire extinguishers across the world, while generation I hot aerosol fire suppression systems are integrated with the oil tank as a whole. Some countries like the U.S., Australia, Russia and China, etc. have already developed standards for manufacturing and quality control of hot aerosol fire extinguishing agents and norms for hot aerosol fire extinguishing system design under different fire protection scenarios. Coolants in hot aerosol fire suppression systems, which are responsible for reducing hot aerosol temperature to avoid secondary fire risk are reviewed for the first time. Cooling effects are generally achieved through vaporization and endothermic chemical decomposition of coolants. Finally, this review discussed areas applying generation I, II or III hot aerosol fire suppression technologies. The generation III hot aerosol fire extinguishing

  1. 77 FR 68829 - Certain Electronic Digital Media Devices and Components Thereof; Notice of Request for Statements...

    Science.gov (United States)

    2012-11-16

    ... electronic digital media devices and components thereof imported by respondents Samsung Electronics Co, Ltd. of Korea; Samsung Electronics America, Inc. of Ridgefield Park, New Jersey; and Samsung Telecommunications America, LLC of Richardson, Texas (collectively ``Samsung''), and cease and desist orders against...

  2. Study of the magnetic compressional mode in a hot particle plasma

    International Nuclear Information System (INIS)

    Stotler, D.P.; Berk, H.L.; Engquist, M.G.

    1985-09-01

    The integral equation for the magnetic compressional mode, accounting for geometrical effects along the field line and using the eikonal approximation across the field line, is solved numerically for the eigenvalues and eigenfunctions. These results reproduce the analytic estimates when there is strong drift reversal. For typical EBT-S parameters, instability is observed for all pressure scale lengths just below those needed for drift reversal, i.e., vertical bar Rpar. delta(P/sub c/ + P/sub perpendicular h/)/2B 2 par. deltar vertical bar > 1 (where P is the particle pressure, c and h refer to cold and hot components, B is the midplane magnetic field, and R is the midplane radius of curvature). If larger core densities are present, a wave-particle resonance arises when the particle drifts are not reversed, causing instability up to much larger pressure scale lengths. Stability for all values of the ratio of hot electron density to core density is obtained with vertical bar Rpar. deltaP/sub c//B 2 par. deltar vertical bar > 1 + P/sub parallel h//P/sub perpendicular h/

  3. Electronic equilibrium as a function of depth in tissue from cobalt-60 point source exposures

    International Nuclear Information System (INIS)

    Myrick, J.A.

    1994-08-01

    The Nuclear Regulatory Commission has set the basic criteria for assessing skin dose stemming from hot particle contaminations. Compliance with 10 CFR 20.101 requires that exposure to the skin be evaluated over a 1 cm 2 area at a depth of 0.007 cm. Skin exposure can arise from both the beta and gamma components of radioactive particles and gamma radiation can contribute significantly to skin doses. The gamma component of dose increases dramatically when layers of protective clothing are interposed between the hot particle source and the skin, and in cases where the hot particle is large in comparison to the range of beta particles. Once the protective clothing layer is thicker than the maximum range of the beta particles, skin dose is due solely to gamma radiation. Charged particle equilibrium is not established at shallow depths. The degree of electronic equilibrium establishment must be assessed for shallow doses to prevent the over-assessment of skin dose because conventional fluence-to-dose conversion factors are not applicable. To assess the effect of electronic equilibrium, selected thicknesses of tissue equivalent material were interposed between radiochromic dye film and a 60 Co hot particle source and dose was measured as a function of depth. These measured values were then compared to models which are used to calculate charged particle equilibrium. The Miller-Reece model was found to agree closely with the experimental data while the Lantz-Lambert model overestimated dose at shallow depths

  4. Texture evolution of experimental silicon steel grades. Part I: Hot rolling

    Energy Technology Data Exchange (ETDEWEB)

    Sandoval Robles, J.A., E-mail: jsandoval.uanl@yahoo.com [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, Ave. Universidad S/N, Cd. Universitaria, San Nicolás de los Garza, Nuevo León C.P. 66450 (Mexico); Salas Zamarripa, A.; Guerrero Mata, M.P. [Universidad Autónoma de Nuevo León, Facultad de Ingeniería Mecánica y Eléctrica, Ave. Universidad S/N, Cd. Universitaria, San Nicolás de los Garza, Nuevo León C.P. 66450 (Mexico); Cabrera, J. [Universitat Politècnica de Catalunya, Departament de Ciència dels Materials I Enginyeria Metal-lúrgica, Av. Diagonal 647, Barcelona 08028 (Spain)

    2017-05-01

    The metallurgical understanding of the deformation processes during the fabrication of non-oriented electrical steels plays a key role in improving their final properties. Texture control and optimization is critical in these steels for the enhancement of their magnetic properties. The aim of the present work is to study the texture evolution of six non-oriented experimental silicon steel grades during hot rolling. These steels were low carbon steel with a silicon content from 0.5 to 3.0 wt%. The first rolling schedule was performed in the austenitic (γ-Fe) region for the steel with a 0.5 wt% of silicon content, while the 1.0 wt% silicon steel was rolled in the two-phase (α+γ) region. Steels with higher silicon content were rolled in the ferritic (α-Fe) region. The second rolling schedule was performed in the α-Fe region. Samples of each stage were analyzed by means of Electron Backscatter Diffraction (EBSD). Findings showed that the texture was random and heterogeneous in all samples after 60% of rolling reduction, which is due to the low deformation applied during rolling. After the second rolling program, localized deformation and substructured grains near to surface were observed in all samples. The Goss {110}<001>texture-component was found in the 0.5 and 1.0 wt.-%silicon steels. This is due to the thermomechanical conditions and the corresponding hot band microstructure obtained after the first program. Moreover, the α<110>//RD and the γ <111>//ND fiber components of the texture presented a considerable increment as the silicon content increases. Future research to be published soon will be related to the texture evolution during the cold-work rolling process. - Highlights: • We analyze six silicon steel experimental grades alloys trough the rolling process. • Material was subjected to a hot deformation process in the α-γ region. • No recrystalization was observed during-after the rolling schedules. • Rise of the magnetic texture components

  5. Detailed SEM-EPMA investigation of high specific radioactivity particles (hot particles)

    International Nuclear Information System (INIS)

    Burin, K.; Tsacheva, Ts.; Mandjoukov, I.; Mandjoukova, B.

    1993-01-01

    Scanning electron microscope (SEM) images and electron probe microanalysis (EPMA) spectra of a group of hot particles collected in Bulgaria after the Chernobyl accident have been obtained. A technique for hot particle localization is described. The object is irradiated for two days with a β source and the resulting autoradiographs show particles location precisely. High resolution x-ray spectrum of each particle has been obtained using EPMA. The distribution of chemical elements is visualized by colour dot maps representing the regions of interest of the spectrum. It is concluded that apart from reactor fuel the investigated hot particles come from either construction materials or materials used for the covering of the damaged reactor. 7 figs., 2 ref

  6. Fabrication and properties of hot pressed bismuth tungstate

    International Nuclear Information System (INIS)

    Streicher, W.L.

    1978-01-01

    Bi 2 WO 6 is a synthetic polar material that is a possible candidate for energy conversion and detection systems. Previous research on this material has been concerned with crystal growth and sintering characteristics of polycrystalline compacts. This study involves itself with the fabrication of polycrystalline compacts by hot pressing techniques. Densities approaching theoretical crystal density were achieved by hot pressing at 850 0 C for one hour with pressures exceeding 35 MPa. Before hot pressing, the sintering range was determined by high temperature dilatometry of unfired Bi 2 WO 6 ceramics. Hot pressed discs were characterized by scanning electron microscopy, differential scanning calorimetry, and x-ray diffraction. Electrical properties were determined by dc resistivity, capacitance, and conductance measurements, ac poling, dc poling, and current-voltage measurements

  7. Study of the heat flux generated by accelerated electrons on the components near the plasma

    International Nuclear Information System (INIS)

    Laugier, J.

    2003-01-01

    Experimental data have shown that a heat flux appears on components situated near the wave guide of the lower hybrid antenna of Tore-Supra. This heat flux is due to the energy release during collisions that occur between the component surface and the electrons accelerated by the high frequency field generated by the antenna. Simulations show that the electrons may reach an energy of 2-3 keV and that the heat flux generated in the shield may reach 10 MW/m 2 . In this work a correlation has been established between the local heat flux due to electron impact and the mean electrical field near the antenna: Φ (W/m 2 ) = 4.10 -4 x E -6 (10 5 V/m). It is also shown that the ratio of electrons that reach the shield is roughly not dependent on the value of the mean electrical field. In the hypothesis of a Gaussian distribution of electron initial velocities this ratio is 10%. (A.C.)

  8. Ensemble Monte Carlo particle investigation of hot electron induced source-drain burnout characteristics of GaAs field-effect transistors

    Science.gov (United States)

    Moglestue, C.; Buot, F. A.; Anderson, W. T.

    1995-08-01

    The lattice heating rate has been calculated for GaAs field-effect transistors of different source-drain channel design by means of the ensemble Monte Carlo particle model. Transport of carriers in the substrate and the presence of free surface charges are also included in our simulation. The actual heat generation was obtained by accounting for the energy exchanged with the lattice of the semiconductor during phonon scattering. It was found that the maximum heating rate takes place below the surface near the drain end of the gate. The results correlate well with a previous hydrodynamic energy transport estimate of the electronic energy density, but shifted slightly more towards the drain. These results further emphasize the adverse effects of hot electrons on the Ohmic contacts.

  9. Two-dimensional simulations of laser–plasma interaction and hot electron generation in the context of shock-ignition research

    Czech Academy of Sciences Publication Activity Database

    Klimo, O.; Psikal, J.; Tikhonchuk, V.T.; Weber, Stefan A.

    2014-01-01

    Roč. 56, č. 5 (2014), 055010 ISSN 0741-3335 R&D Projects: GA MŠk ED1.1.00/02.0061; GA MŠk EE2.3.20.0279 Grant - others:ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; LaserZdroj (OP VK 3)(XE) CZ.1.07/2.3.00/20.0279 Institutional support: RVO:68378271 Keywords : laser plasma interaction * stimulated Raman scattering * hot electrons * particle-in-cell simulation Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.186, year: 2014

  10. Comparison of PIV and Hot-Wire statistics of turbulent boundary layer

    International Nuclear Information System (INIS)

    Dróżdż, A; Uruba, V

    2014-01-01

    The paper shows a cross checking of turbulent boundary layer measurements using large field of view PIV and hot-wire anemometry techniques. The time-resolved PIV method was used for the experiments. The measuring plane was oriented perpendicularly to the wall and parallel to the mean flow. Hot wire measurement has been performed using the special probe with perpendicular hot wire. The HW point measurements were performed in the same place as PIV experiments. The hot-wire probe has the wire length of l + < 20 in considered range of Reynolds numbers. Various evaluation methods were applied on PIV data. The profiles of statistical characteristics of streamwise velocity components were evaluated from the data. Mean values, standard deviations as well as skewness and kurtosis coefficients were compared for a few values of Re θ . Reynolds number ranges from 1000 to 5500. The result shows that with the increasing Reynolds number the attenuation of fluctuations maximum in PIV measurements occurs with respect to Hot-Wire measurements, however representation of velocity fluctuations using the PIV method is satisfactory. The influence of wall-normal fluctuation component on Hot-Wire near wall peak was also investigated.

  11. Conceptual layout design of CFETR Hot Cell Facility

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Zheng, E-mail: gongz@mail.ustc.edu.cn [University of Science and Technology of China, Hefei 230026 (China); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Qi, Minzhong, E-mail: qiminzhong@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Cheng, Yong, E-mail: chengyong@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Song, Yuntao, E-mail: songyt@ipp.ac.cn [University of Science and Technology of China, Hefei 230026 (China); Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China)

    2015-11-15

    Highlights: • This article proposed a conceptual layout design for CFETR. • The design principles are to support efficient maintenance to ensure the realization of high duty time. • The preliminary maintenance process and logistics are described in detail. • Life cycle management, maneuverability, risk and safety are in the consideration of design. - Abstract: CFETR (China Fusion Engineering Test Reactor) is new generation of Tokomak device beyond EAST in China. An overview of hot cell layout design for CFETR has been proposed by ASIPP&USTC. Hot Cell, as major auxiliary facility, not only plays a pivotal role in supporting maintenance to meet the requirements of high duty time 0.3–0.5 but also supports installation and decommissioning. Almost all of the Tokomak devices are lateral handling internal components like ITER and JET, but CFETR maintain the blanket module from 4 vertical ports, which is quite a big challenge for the hot cell layout design. The activated in-vessel components and several diagnosis instruments will be repaired and refurbished in the Hot Cell Facility, so the appropriate layout is very important to the Hot Cell Facility to ensure the high duty time, it is divided into different parts equipped with a variety of RH equipment and diagnosis devices based on the functional requirements. The layout of the Hot Cell Facility should make maintenance process more efficient and reliable, and easy to service and rescue when a sudden events taking place, that is the capital importance issue considered in design.

  12. Component-Level Electronic-Assembly Repair (CLEAR) Spacecraft Circuit Diagnostics by Analog and Complex Signature Analysis

    Science.gov (United States)

    Oeftering, Richard C.; Wade, Raymond P.; Izadnegahdar, Alain

    2011-01-01

    The Component-Level Electronic-Assembly Repair (CLEAR) project at the NASA Glenn Research Center is aimed at developing technologies that will enable space-flight crews to perform in situ component-level repair of electronics on Moon and Mars outposts, where there is no existing infrastructure for logistics spares. These technologies must provide effective repair capabilities yet meet the payload and operational constraints of space facilities. Effective repair depends on a diagnostic capability that is versatile but easy to use by crew members that have limited training in electronics. CLEAR studied two techniques that involve extensive precharacterization of "known good" circuits to produce graphical signatures that provide an easy-to-use comparison method to quickly identify faulty components. Analog Signature Analysis (ASA) allows relatively rapid diagnostics of complex electronics by technicians with limited experience. Because of frequency limits and the growing dependence on broadband technologies, ASA must be augmented with other capabilities. To meet this challenge while preserving ease of use, CLEAR proposed an alternative called Complex Signature Analysis (CSA). Tests of ASA and CSA were used to compare capabilities and to determine if the techniques provided an overlapping or complementary capability. The results showed that the methods are complementary.

  13. DARWIN-HC: A Tool to Predict Hot Corrosion of Nickel-Based Turbine Disks, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Hot Corrosion of turbine engine components has been studied for many years. The underlying mechan-isms of Type I Hot Corrosion and Type II Hot Corrosion are...

  14. DARWIN-HC: A Tool to Predict Hot Corrosion of Nickel-Based Turbine Disks, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Hot Corrosion of turbine engine components has been studied for many years. The underlying mechan-isms of Type I Hot Corrosion and Type II Hot Corrosion are...

  15. Hot rolling and annealing effects on the microstructure and mechanical properties of ODS austenitic steel fabricated by electron beam selective melting

    Science.gov (United States)

    Gao, Rui; Ge, Wen-jun; Miao, Shu; Zhang, Tao; Wang, Xian-ping; Fang, Qian-feng

    2016-03-01

    The grain morphology, nano-oxide particles and mechanical properties of oxide dispersion strengthened (ODS)-316L austenitic steel synthesized by electron beam selective melting (EBSM) technique with different post-working processes, were explored in this study. The ODS-316L austenitic steel with superfine nano-sized oxide particles of 30-40 nm exhibits good tensile strength (412 MPa) and large total elongation (about 51%) due to the pinning effect of uniform distributed oxide particles on dislocations. After hot rolling, the specimen exhibits a higher tensile strength of 482 MPa, but the elongation decreases to 31.8% owing to the introduction of high-density dislocations. The subsequent heat treatment eliminates the grain defects induced by hot rolling and increases the randomly orientated grains, which further improves the strength and ductility of EBSM ODS-316L steel.

  16. Analysis of electron spin resonance spectra of irradiated gingers: Organic radical components derived from carbohydrates

    International Nuclear Information System (INIS)

    Yamaoki, Rumi; Kimura, Shojiro; Ohta, Masatoshi

    2010-01-01

    Electron spin resonance (ESR) spectral characterizations of gingers irradiated with electron beam were studied. Complex asymmetrical spectra (near g=2.005) with major spectral components (line width=2.4 mT) and minor signals (at 6 mT apart) were observed in irradiated gingers. The spectral intensity decreased considerably 30 days after irradiation, and continued to decrease steadily thereafter. The spectra simulated on the basis of characteristics of free radical components derived from carbohydrates in gingers are in good agreement with the observed spectra. Analysis showed that shortly after irradiation the major radical components of gingers were composed of radical species derived from amylose and cellulose, and the amylose radicals subsequently decreased considerably. At 30 days after irradiation, the major radical components of gingers were composed of radical species derived from cellulose, glucose, fructose or sucrose.

  17. Hot Deformation Behavior of Hot-Extruded AA7175 Through Hot Torsion Tests.

    Science.gov (United States)

    Lee, Se-Yeon; Jung, Taek-Kyun; Son, Hyeon-Woo; Kim, Sang-Wook; Son, Kwang-Tae; Choi, Ho-Joon; Oh, Sang-Ho; Lee, Ji-Woon; Hyun, Soong-Keun

    2018-03-01

    The hot deformation behavior of hot-extruded AA7175 was investigated with flow curves and processing maps through hot torsion tests. The flow curves and the deformed microstructures revealed that dynamic recrystallization (DRX) occurred in the hot-extruded AA7175 during hot working. The failure strain was highest at medium temperature. This was mainly influenced by the dynamic precipitation of fine rod-shaped MgZn2. The processing map determined the optimal deformation condition for the alloy during hot working.

  18. Impact Factors Analysis of the Hot Side Temperature of Thermoelectric Module

    Science.gov (United States)

    Zhang, Xingyu; Tan, Gangfeng; Yang, Bo

    2018-03-01

    The thermoelectric generator (TEG) plays a crucial role in converting the waste energy of exhaust into electricity, which ensures energy saving and increased fuel utilization efficiency. In the urban driving cycle, frequent vehicle operation, like deceleration or acceleration, results in continuous variation of the exhaust temperature. In order to make the operating performance stable, and to weaken the adverse effects of the frequent variation of the exhaust temperature on the lifetime and work efficiency of the electronic components of TEG systems, the output voltage of the thermoelectric (TE) module should stay more stable. This article provides an improved method for the temperature stability of the TE material hot side based on sandwiching material. From the view of the TEG system's average output power and the hot side temperature stability of the TE material, the analyzing factors, including the fluctuation frequency of the exhaust temperature and the physical properties and thickness of the sandwiching material are evaluated, respectively, in the sine and new European driving cycle (NEDC) fluctuation condition of the exhaust temperature. The results show few effects of sandwiching material thickness with excellent thermal conductivity on the average output power. During the 150-170 s of the NEDC test condition, the minimum hot side temperatures with a BeO ceramic thickness of 2 mm and 6 mm are, respectively, 537.19 K and 685.70 K, which shows the obvious effect on the hot side temperature stability of the BeO ceramic thickness in the process of acceleration and deceleration of vehicle driving.

  19. Electron-positron pair production in a hot accretion plasma around a massive black hole

    International Nuclear Information System (INIS)

    Takahara, Fumio; Kusunose, Masaaki.

    1985-01-01

    We investigate the electron-positron pair production in a hot accretion plasma around a supermassive black hole in connection with active galactic nuclei. Assuming that an optically thin two-temperature plasma is produced in the vicinity of the central black hole, we examine the condition for the significant pair production by comparing relevant time scales. Since the pair production is dominated by collisions between hard photons, the conditions for significant pair production depend on the production rate of hard photons. We examine the case where the unsaturated Comptonization of soft photons produces hard photons as well as that of bremsstrahlung. We show that significant pair production occurs for a moderately high accretion rate with relatively slow accretion flow as compared to the free fall velocity in both cases. Possible consequences of pair production are briefly discussed. (author)

  20. Hot Ductility Behavior of an 8 Pct Cr Roller Steel

    Science.gov (United States)

    Wang, Zhenhua; Sun, Shuhua; Shi, Zhongping; Wang, Bo; Fu, Wantang

    2015-04-01

    The hot ductility of an 8 pct Cr roller steel was determined between 1173 K and 1473 K (900 °C and 1200 °C) at strain rates of 0.01 to 10 s-1 through tensile testing. The fracture morphology was observed using scanning electron microscopy, and the microstructure was examined through optical microscopy and transmission electron microscopy. The dependence of the hot ductility behavior on the deformation conditions, grain size, and precipitation was analyzed. The relationship between the reduction in area and the natural logarithm of the Zener-Hollomon parameter (ln Z) was found to be a second-order polynomial. When ln Z was greater than 40 s-1, the hot ductility was poor and fracture was mainly caused by incompatible deformation between the grains. When ln Z was between 32 and 40 s-1, the hot ductility was excellent and the main fracture mechanism was void linking. When ln Z was below 32 s-1, the hot ductility was poor and fracture was mainly caused by grain boundary sliding. A fine grain structure is beneficial for homogenous deformation and dynamic recrystallization, which induces better hot ductility. The effect of M7C3 carbide particles dispersed in the matrix on the hot ductility was small. The grain growth kinetics in the 8 pct Cr steel were obtained between 1373 K and 1473 K (1100 °C and 1200 °C). Finally, optimized preheating and forging procedures for 8 pct Cr steel rollers are provided.

  1. Ion emission from laser-produced plasmas with two electron temperatures

    International Nuclear Information System (INIS)

    Wickens, L.M.; Allen, J.E.; Rumsby, P.T.

    1978-01-01

    An analytic theory for the expansion of a laser-produced plasma with two electron temperatures is presented. It is shown that from the ion-emission velocity spectrum such relevant parameters as the hot- to -cold-electron density ratio, the absolute hot- and cold-electron temperatures, and a sensitive measure of hot- and cold-electron temperature ratio can be deduced. A comparison with experimental results is presented

  2. Failure analysis a practical guide for manufacturers of electronic components and systems

    CERN Document Server

    Bâzu, Marius

    2011-01-01

    Failure analysis is the preferred method to investigate product or process reliability and to ensure optimum performance of electrical components and systems. The physics-of-failure approach is the only internationally accepted solution for continuously improving the reliability of materials, devices and processes. The models have been developed from the physical and chemical phenomena that are responsible for degradation or failure of electronic components and materials and now replace popular distribution models for failure mechanisms such as Weibull or lognormal. Reliability engineers nee

  3. Radiation load experiments with electronic components of the SYMPHONIE satellite

    International Nuclear Information System (INIS)

    Spencker, A.; Wagemann, H.G.; Braeunig, D.

    1975-09-01

    This report surveys fundamentals, realization and results of irradiation experiments which applied to 36 different electronic components of the Symphonie satellite and which were completed at the HMI Berlin and the C.N.E.T. Lannion in the years 1972/73. In a general section the evaluation of equivalent fluencies concerning 1 MeV electrons as radiation simulating the extraterrestric particle spectra with regard to the well-known semiconductor damage mechanisms is discussed. Then the realization of irradiation testing for the Symphonie satellite is described. Three selected examples demonstrate typical failure modes of semiconductor devices under radiation stress: Finally the main experimental results are shown in a standardized manner; a survey in English is given on p. 44. (orig.) [de

  4. Electron-cyclotron-resonant-heated electron distribution functions

    International Nuclear Information System (INIS)

    Matsuda, Y.; Nevins, W.M.; Cohen, R.H.

    1981-01-01

    Recent studies at Lawrence Livermore National Laboratory (LLNL) with a bounce-averaged Fokker-Planck code indicate that the energetic electron tail formed by electron-cyclotron resonant heating (ECRH) at the second harmonic is not Maxwellian. We present the results of our bounce-averaged Fokker-Planck code along with some simple analytic models of hot-electron distribution functions

  5. Quality and reliability assurance of electronic components in small-scale and middle-sized plants

    International Nuclear Information System (INIS)

    Becker, P.

    1982-01-01

    Electronic components are forever finding their way into new fields of application and have an ever increasing influence on the quality and reliability of the products in which they are used. The user has very negligible influence on the production methods used for the manufacture of the components and the element properties. (orig.) [de

  6. Separation of electron ion ring components (computational simulation and experimental results)

    International Nuclear Information System (INIS)

    Aleksandrov, V.S.; Dolbilov, G.V.; Kazarinov, N.Yu.; Mironov, V.I.; Novikov, V.G.; Perel'shtejn, Eh.A.; Sarantsev, V.P.; Shevtsov, V.F.

    1978-01-01

    The problems of the available polarization value of electron-ion rings in the regime of acceleration and separation of its components at the final stage of acceleration are studied. The results of computational simulation by use of the macroparticle method and experiments on the ring acceleration and separation are given. The comparison of calculation results with experiment is presented

  7. Fabrication of an Aluminum Based Hot Electron Mixer for Terahertz Applications

    Science.gov (United States)

    Echternach, P. M.; LeDuc, H. G.; Skalare, A.; McGrath, W. R.

    2000-01-01

    Aluminum based diffusion cooled hot electron bolometers (HEB) mixers, predicted to have better noise, bandwidth and to require less LO power than Nb based diffusion cooled HEBs, have been fabricated. Preliminary DC tests were performed. The bolometer elements consisted of short (0.1 to 0.3 micron), narrow (0.08 to 0. 15 micron) and thin (11 nm) aluminum wires connected to large contact pads consisting of a novel trilayer Al/Ti/Au. The patterns were defined by electron beam lithography and the metal deposition involved a double angle process, the Aluminum wires being deposited straight on and the pads being deposited at a 45 degree angle without breaking vacuum. The Al/Ti/Au trilayer was developed to provide a way of making contact between the aluminum wire and the gold antenna. The Titanium layer acts as a diffusion barrier to avoid damage of the Aluminum contact and bolometer wire and to lower the transition temperature of the pads to below that of the bolometer wire. The Au layer avoids the formation of an oxide on the Ti layer and provides good electrical contact to the IF/antenna structure. The resistance of the bolometers as a function of temperature was measured. It is clear that below the transition temperature of the wire (1.8K) but above the transition temperature of the contact pads (0.6K), the proximity effect drives most of the bolometer wire normal, causing a very broad transition. This effect should not affect the performance of the bolometers since they will be operated at a temperature below the TC of the pads. This is evident from the IV characteristics measured at 0.3K. RF characterization tests will begin shortly.

  8. Structure and characteristics of the hot pressed hydroxyapatite/poly-L-lactide composite

    Directory of Open Access Journals (Sweden)

    Ignjatović Nenad L.

    2002-01-01

    Full Text Available Hydroxyapatite/poly-L-lactide (HAp/PLL composite biomaterial can be obtained by different processing methods. Three-dimensional blocks of HAp/PLLA composite biomaterial with mechanical characteristics close to the natural bone tissue can be obtained by hot pressing procedure. Effects of synthesis and compacting on the structure and characteristics of the HAp/PLLA composite biomaterial were studied in this work. Using wade angle X-ray structural analyses (WAXS, differentially scanning calorimetry (DSC, thermogravimetric analysis (TGA and infrared (IR spectroscopy, the changes occurring in the material during synthesis and hot pressing were monitored. Surface microstructure was analyzed by scanning electronic microscopy (SEM coupled with electron-dispersion analysis (EDX. The results obtained indicate a possible decrease in the degree of crystallinity with hot pressing time increase. A block of HAp/PLLA composite biomaterial with 1.6 times lower crystallinity of the polymer phase was obtained by hot pressing in a given time interval with a maximum of 60 minutes. Results of TG analysis show that PLLA stability decreases with increasing hot pressing time, and vice versa. IR study proved that neither destructive changes in constituents nor formation of new phases occurred during hot pressing.

  9. Nuclear electronic components of surface contamination monitor based on multi-electrode proportional counter

    International Nuclear Information System (INIS)

    Du Xiangyang; Zhang Yong; Han Shuping; Rao Xianming; Fang Jintu

    2001-01-01

    The nuclear electronic components applying in Portal Monitor and Hands and Feet Surface Contamination Monitor were based on modern integrated circuit are introduced. The detailed points in circuit design and manufacturing technique are analyzed

  10. The effect of zinc bath temperature on the morphology, texture and corrosion behaviour of industrially produced hot-dip galvanized coatings

    Directory of Open Access Journals (Sweden)

    A. Bakhtiari

    2014-03-01

    Full Text Available The purpose of this work is to identify the influence of zinc bath temperature on the morphology, texture and corrosion behavior of hot-dip galvanized coatings. Hot-dip galvanized samples were prepared at temperature in the range of 450-480 °C in steps of 10 °C, which is the conventional galvanizing temperature range in the galvanizing industries. The morphology of coatings was examined with optical microscopy and scanning electron microscopy (SEM. The composition of the coating layers was determined using energy dispersive spectroscopy (EDS analysis. The texture of the coatings was evaluated using X-ray diffraction. Corrosion behavior was performed using salt spray cabinet test and Tafel extrapolation test. From the experimental results, it was found that increasing the zinc bath temperature affects the morphology of the galvanized coatings provoking the appearance of cracks in the coating structure. These cracks prevent formation of a compact structure. In addition, it was concluded that (00.2 basal plane texture component was weakened by increasing the zinc bath temperature and, conversely, appearance of (10.1 prism component, (20.1 high angle pyramidal component and low angle component prevailed. Besides, coatings with strong (00.2 texture component and weaker (20.1 components have better corrosion resistance than the coatings with weak (00.2 and strong (20.1 texture components. Furthermore, corrosion resistance of the galvanized coatings was decreased by increasing the zinc bath temperature.

  11. Twisted electron-acoustic waves in plasmas

    International Nuclear Information System (INIS)

    Aman-ur-Rehman; Ali, S.; Khan, S. A.; Shahzad, K.

    2016-01-01

    In the paraxial limit, a twisted electron-acoustic (EA) wave is studied in a collisionless unmagnetized plasma, whose constituents are the dynamical cold electrons and Boltzmannian hot electrons in the background of static positive ions. The analytical and numerical solutions of the plasma kinetic equation suggest that EA waves with finite amount of orbital angular momentum exhibit a twist in its behavior. The twisted wave particle resonance is also taken into consideration that has been appeared through the effective wave number q_e_f_f accounting for Laguerre-Gaussian mode profiles attributed to helical phase structures. Consequently, the dispersion relation and the damping rate of the EA waves are significantly modified with the twisted parameter η, and for η → ∞, the results coincide with the straight propagating plane EA waves. Numerically, new features of twisted EA waves are identified by considering various regimes of wavelength and the results might be useful for transport and trapping of plasma particles in a two-electron component plasma.

  12. Quasi-static electron density fluctuations of atoms in hot compressed matter

    International Nuclear Information System (INIS)

    Grimaldi, F.; Grimaldi-Lecourt, A.

    1982-01-01

    The standard theoretical methods for the calculation of properties of hot compressed matter lead to a description based on the Average Atom model. In this model the degenerate orbitals are populated with the Fermi-Dirac (FD) density, partitioned according to the binomial distribution. Since the one particle picture is inadequate to evaluate reliable optical properties, a method involving correlated population fluctuations, but limited to unrelaxed orbitals and lacking time dependence, has been examined. The probability distribution of fluctuations in a particular level is evaluated through a decoupling procedure. The method is carried out self consistently. For each level this leads to the definition of an effective 1st order ionization energy as a statistical sum of all possible transition energies. As a result the effective number of electrons exchanged with the outside weights the chemical potential. This defines an effective chemical potential μsup(k) for each level. In many cases of interest the statistics leads to FD type average occupation numbers. This allows a treatment of the continuum in a Thomas-Fermi like model using the effective ionization energy and μsup(k). We obtain a simultaneous description of charge rearrangements and net fluctuations in the Wigner-Seitz cell. The discussion is supported by numerical results for iron. (author)

  13. Solutions to mitigate heat loads due to electrons on sensitive components of ITER HNB beamlines

    Energy Technology Data Exchange (ETDEWEB)

    Sartori, Emanuele, E-mail: emanuele.sartori@gmail.com [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova (Italy); Veltri, Pierluigi; Dalla Palma, Mauro; Agostinetti, Piero [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova (Italy); Hemsworth, Ronald; Singh, Mahendrajit [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Serianni, Gianluigi [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete SpA), C.so Stati Uniti 4, 35127 Padova (Italy)

    2016-11-01

    Highlights: • Energetic electrons leaking out of the ITER HNB accelerator are simulated. • Electrons generated along the ITER HNB beamline are simulated. • Heat loads and heat load maps on cryopumps are calculated for ITER HNB and test facility. • Protection solutions that will be installed are presented and their effect discussed. - Abstract: The operation of neutral beam injectors for plasma heating and current drive in a fusion device provides challenges in the thermal management of beamline components. Sensitive components such as the cryogenic pumps at beamline periphery shall be protected from the heat flux due to stray electrons. These are emitted by the negative ion accelerator or generated along the beamline by interaction of fast electrons, ions or atoms with background gas and surfaces. In this article the case of the ITER Heating Neutral Beam (HNB) and its test facility MITICA is discussed, for which the beam parameters and the required pulse length of one hour is a major leap forward with respect to the present experience with neutral beam systems. The engineering solutions adopted for effective cryopump protection against the heat load from electrons are described. The use of three-dimensional numerical simulations of particle trajectories in the complex geometry of the beamline was needed for the quantitative estimations of the heat loads. The presented solutions were optimized to minimize the impact on gas pumping and on the functionality of other components.

  14. Optically stimulated luminescence of electronic components for forensic, retrospective, and accident dosimetry

    International Nuclear Information System (INIS)

    Inrig, E.L.; Godfrey-Smith, D.I.; Khanna, S.

    2008-01-01

    This study investigated the optically stimulated luminescence (OSL) response of electronic components found within portable electronic devices such as cell phones and pagers, portable computers, music and video players, global positioning system receivers, cameras, and digital watches. The analysis of components extracted from these ubiquitous devices was proposed for applications ranging from rapid accident dose reconstruction to the tracking and attribution of gamma-emitting radiological materials. Surface-mount resistors with alumina porcelain substrates consistently produced OSL following irradiation, with minimum detectable doses on the order of 10 mGy for a typical sample. Since the resistor ceramics were found to exhibit anomalous fading, dose reconstruction procedures were developed to correct for this using laboratory measurements of fading rates carried out over approximately 3 months. Two trials were conducted in which cellular phones were affixed to an anthropomorphic phantom and irradiated using gamma-ray sources; ultimately, analysis of the devices used in these trials succeeded in reconstructing doses in the range of 0.1-0.6Gy

  15. Experimental study of hot electrons propagation and energy deposition in solid or laser-shock compressed targets: applications to fast igniter; Etude experimentale de la propagation et du depot d'energie d'electrons rapides dans une cible solide ou comprimee par choc laser: application a l'allumeur rapide

    Energy Technology Data Exchange (ETDEWEB)

    Pisani, F

    2000-02-15

    In the fast igniter scheme, a recent approach proposed for the inertial confinement fusion, the idea is to dissociate the fuel ignition phase from its compression. The ignition phase would be then achieved by means of an external energy source: a fast electron beam generated by the interaction with an ultra-intense laser. The main goal of this work is to study the mechanisms of the hot electron energy transfer to the compressed fuel. We intent in particular to study the role of the electric and collisional effects involved in the hot electron propagation in a medium with properties similar to the compressed fuel. We carried out two experiments, one at the Vulcan laser facility (England) and the second one at the new LULI 100 TW laser (France). During the first experiment, we obtained the first results on the hot electron propagation in a dense and hot plasma. The innovating aspect of this work was in particular the use of the laser-shock technique to generate high pressures, allowing the strongly correlated and degenerated plasma to be created. The role of the electric and magnetic effects due to the space charge associated with the fast electron beam has been investigated in the second experiment. Here we studied the propagation in materials with different electrical characteristics: an insulator and a conductor. The analysis of the results showed that only by taking into account simultaneously the two propagation mechanisms (collisions and electric effects) a correct treatment of the energy deposition is possible. We also showed the importance of taking into account the induced modifications due to the electrons beam crossing the target, especially the induced heating. (author)

  16. Electron Shock Ignition of Inertial Fusion Targets

    International Nuclear Information System (INIS)

    Shang, W. L.; Betti, R.; Hu, S. X.; Woo, K.; Hao, L.

    2017-01-01

    Here, it is shown that inertial fusion targets designed with low implosion velocities can be shock ignited using laser–plasma interaction generated hot electrons (hot-e) to obtain high-energy gains. These designs are robust to multimode asymmetries and are predicted to ignite even for significantly distorted implosions. Electron shock ignition requires tens of kilojoules of hot-e, which can only be produced on a large laser facility like the National Ignition Facility, with the laser to hot-e conversion efficiency greater than 10% at laser intensities ~10 16 W/cm 2 .

  17. 77 FR 34063 - Certain Electronic Devices, Including Mobile Phones and Tablet Computers, and Components Thereof...

    Science.gov (United States)

    2012-06-08

    ... Phones and Tablet Computers, and Components Thereof Institution of Investigation AGENCY: U.S... the United States after importation of certain electronic devices, including mobile phones and tablet... mobile phones and tablet computers, and components thereof that infringe one or more of claims 1-3 and 5...

  18. The Contribution of "Cool" and "Hot" Components of Decision-Making in Adolescence: Implications for Developmental Psychopathology

    Science.gov (United States)

    Seguin, Jean R.; Arseneault, Louise; Tremblay, Richard E.

    2007-01-01

    Impairments in either "cool" or "hot" processes may represent two pathways to deficient decision-making. Whereas cool processes are associated with cognitive and rational decisions, hot processes are associated with emotional, affective, and visceral processes. In this study, 168 boys were administered a card-playing task at ages 13 and 14 years…

  19. Experimental approach to Chernobyl hot particles

    International Nuclear Information System (INIS)

    Tcherkezian, V.; Shkinev, V.; Khitrov, L.; Kolesov, G.

    1994-01-01

    An experimental approach to the investigation of Chernobyl hot particles and some results are presented in this study. Hot particles (HP) were picked out from soil samples collected during the 1986-1990 radiogeochemical expeditions in the contaminated zone (within 30 km of the Nuclear Power Plant). A number of hot particles were studied to estimate their contribution to the total activity, investigate their surface morphology and determine the size distribution. Hot particles contribution to the total activity in the 30 km zone was found to be not less than 65%. Investigation of HP element composition (by neutron activation analysis and EPMA) and radionuclide composition (direct alpha- and gamma-spectrometry, including determination of Pu and Am in Hp) revealed certain peculiarities of HP, collected in the vicinity of the damaged Nuclear Power Plant. Some particles were shown to contain uranium and fission products in proportion to one another, correlating with those in the partially burnt fuel, which proves their 'fuel' origin. Another part of the HP samples has revealed element fractionation as well as the presence of some terrestrial components. (Author)

  20. Optical pumping of hot phonons in GaAs

    International Nuclear Information System (INIS)

    Collins, C.L.; Yu, P.Y.

    1982-01-01

    Optical pumping of hot LO phonons in GaAs has been studied as a function of the excitation photon frequency. The experimental results are in good agreement with a model calculation which includes both inter- and intra-valley electron-phonon scatterings. The GAMMA-L and GAMMA-X intervalley electron-phonon interactions in GaAs have been estimated

  1. Electron backscatter diffraction study of dislocation content of a macrozone in hot-rolled Ti-6Al-4V alloy

    International Nuclear Information System (INIS)

    Britton, T. Ben; Birosca, Soran; Preuss, Michael; Wilkinson, Angus J.

    2010-01-01

    We compare the dislocation substructure within macrozone and non-macrozone regions of hot-rolled Ti-6Al-4 V. Hough-based and cross-correlation-based analysis of electron backscatter diffraction (EBSD) patterns are used to establish the grain orientations and intra-granular misorientations, respectively. The set of geometrically necessary dislocations (GNDs) that support measured lattice curvatures and minimize the total GND line energy are calculated. The GND content in the macrozone is approximately twice that in the non-macrozone region, and GNDs are present at densities ∼10 times higher than GNDs.

  2. An investigation into hot deformation of aluminum alloy 5083

    Energy Technology Data Exchange (ETDEWEB)

    Hosseinipour, S.J. [Manufacturing Engineering Department, School of Mechanical Engineering, Nushirvani Institute of Technology, University of Mazandaran, P.O. Box 484, Shariati Avenue, Babol (Iran, Islamic Republic of)], E-mail: j.hosseini@nit.ac.ir

    2009-02-15

    In this paper the hot deformation behavior of Al-5083 commercial alloy is studied. For this purpose, hot tensile tests have been carried out at various temperatures and strain rates. Velocity jump tests have been performed to determine stress-strain rate curves at various temperatures and strains. The microstructures have been studied by optical and electron microscopy (SEM). It is found that continuous recrystallization occurs during hot deformation of the AA5083. Maximum elongation about 250% is obtained at 450 deg. C and strain rate of 0.005 s{sup -1}. The failure surface is narrow and failure occurs by necking.

  3. An investigation into hot deformation of aluminum alloy 5083

    International Nuclear Information System (INIS)

    Hosseinipour, S.J.

    2009-01-01

    In this paper the hot deformation behavior of Al-5083 commercial alloy is studied. For this purpose, hot tensile tests have been carried out at various temperatures and strain rates. Velocity jump tests have been performed to determine stress-strain rate curves at various temperatures and strains. The microstructures have been studied by optical and electron microscopy (SEM). It is found that continuous recrystallization occurs during hot deformation of the AA5083. Maximum elongation about 250% is obtained at 450 deg. C and strain rate of 0.005 s -1 . The failure surface is narrow and failure occurs by necking

  4. THERMAL RESPONSE OF A SOLAR-LIKE ATMOSPHERE TO AN ELECTRON BEAM FROM A HOT JUPITER: A NUMERICAL EXPERIMENT

    International Nuclear Information System (INIS)

    Gu, P.-G.; Suzuki, Takeru K.

    2009-01-01

    We investigate the thermal response of the atmosphere of a solar-type star to an electron beam injected from a hot Jupiter by performing a one-dimensional MHD numerical experiment with nonlinear wave dissipation, radiative cooling, and thermal conduction. In our experiment, the stellar atmosphere is non-rotating and is modeled as a one-dimensional open flux tube expanding super-radially from the stellar photosphere to the planet. An electron beam is assumed to be generated from the reconnection site of the planet's magnetosphere. The effects of the electron beam are then implemented in our simulation as dissipation of the beam momentum and energy at the base of the corona where the Coulomb collisions become effective. When the sufficient energy is supplied by the electron beam, a warm region forms in the chromosphere. This warm region greatly enhances the radiative fluxes corresponding to the temperature of the chromosphere and transition region. The warm region can also intermittently contribute to the radiative flux associated with the coronal temperature due to the thermal instability. However, owing to the small area of the heating spot, the total luminosity of the beam-induced chromospheric radiation is several orders of magnitude smaller than the observed Ca II emissions from HD 179949.

  5. Comparison of thermal behavior of natural and hot-washed sisal fibers based on their main components: Cellulose, xylan and lignin. TG-FTIR analysis of volatile products

    Energy Technology Data Exchange (ETDEWEB)

    Benítez-Guerrero, Mónica, E-mail: monica_benitez_guerrero@yahoo.es [Departamento de Ingeniería Civil, Materiales y Fabricación, Universidad de Málaga, Escuela de Ingenierías, C/ Dr. Ortiz Ramos s/n, Campus Teatinos, 29071 Málaga (Spain); López-Beceiro, Jorge [Departamento de Ingeniería Industrial II, Escola Politécnica Superior, Universidade da Coruña, Avda. Mendizábal, 15403 Ferrol (Spain); Sánchez-Jiménez, Pedro E. [Instituto de Ciencia de Materiales de Sevilla, CSIC-Universidad de Sevilla, C/ Américo Vespucio 49, 41092 Sevilla (Spain); Pascual-Cosp, José [Departamento de Ingeniería Civil, Materiales y Fabricación, Universidad de Málaga, Escuela de Ingenierías, C/ Dr. Ortiz Ramos s/n, Campus Teatinos, 29071 Málaga (Spain)

    2014-04-01

    Highlights: • Thermal decomposition of sisal fibers has been discussed. • Decompositions of lignocellulosic components and sisal are compared by TXRD and TG-FTIR. • Hot washing reduces the temperature range in which sisal decomposition occurs. • Sisal cellulose decomposition goes by an alternative route to levoglucosan generation. - Abstract: This paper presents in a comprehensive way the thermal behavior of natural and hot-washed sisal fibers, based on the fundamental components of lignocellulosic materials: cellulose, xylan and lignin. The research highlights the influence exerted on the thermal stability of sisal fibers by other constituents such as non-cellulosic polysaccharides (NCP) and mineral matter. Thermal changes were investigated by thermal X-ray diffraction (TXRD), analyzing the crystallinity index (%Ic) of cellulosic samples, and by simultaneous thermogravimetric and differential thermal analysis coupled with Fourier-transformed infrared spectrometry (TG/DTA-FTIR), which allowed to examine the evolution of the main volatile compounds evolved during the degradation under inert and oxidizing atmospheres. The work demonstrates the potential of this technique to elucidate different steps during the thermal decomposition of sisal, providing extensible results to other lignocellulosic fibers, through the analysis of the evolution of CO{sub 2}, CO, H{sub 2}O, CH{sub 4}, acetic acid, formic acid, methanol, formaldehyde and 2-butanone, and comparing it with the volatile products from pyrolysis of the biomass components. The hydroxyacetaldehyde detected during pyrolysis of sisal is indicative of an alternative route to that of levoglucosan, generated during cellulose pyrolysis. Hot-washing at 75 °C mostly extracts non-cellulosic components of low decomposition temperature, and reduces the range of temperature in which sisal decomposition occurs, causing a retard in the pyrolysis stage and increasing Tb{sub NCP} and Tb{sub CEL}, temperatures at the

  6. Suppression of cyclotron instability in Electron Cyclotron Resonance ion sources by two-frequency heating

    International Nuclear Information System (INIS)

    Skalyga, V.; Izotov, I.; Mansfeld, D.; Kalvas, T.; Koivisto, H.; Komppula, J.; Kronholm, R.; Laulainen, J.; Tarvainen, O.

    2015-01-01

    Multiple frequency heating is one of the most effective techniques to improve the performance of Electron Cyclotron Resonance (ECR) ion sources. The method increases the beam current and average charge state of the extracted ions and enhances the temporal stability of the ion beams. It is demonstrated in this paper that the stabilizing effect of two-frequency heating is connected with the suppression of electron cyclotron instability. Experimental data show that the interaction between the secondary microwave radiation and the hot electron component of ECR ion source plasmas plays a crucial role in mitigation of the instabilities

  7. Effect of electron emission on an ion sheath structure

    International Nuclear Information System (INIS)

    Mishra, M K; Phukan, A; Chakraborty, M

    2014-01-01

    This article reports on the variations of ion sheath structures due to the emission of both hot and cold electrons in the target plasma region of a double plasma device. The ion sheath is produced in front of a negatively biased plate. The plasma is produced by hot filament discharge in the source region, and no discharge is created in the target region of the device. The plate is placed in the target (diffused plasma) region where cold electron emitting filaments are present. These cold electrons are free from maintenance of discharge, which is sustained in the source region. The hot ionizing electrons are present in the source region. Three important parameters are changed by both hot and cold electrons i.e. plasma density, plasma potential and electron temperature. The decrease in plasma potential and the increase in plasma density lead to the contraction of the sheath. (paper)

  8. Effects of electron pressure anisotropy on current sheet configuration

    Energy Technology Data Exchange (ETDEWEB)

    Artemyev, A. V., E-mail: aartemyev@igpp.ucla.edu; Angelopoulos, V.; Runov, A. [Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90095 (United States); Vasko, I. Y. [Space Research Institute, RAS, Moscow (Russian Federation)

    2016-09-15

    Recent spacecraft observations in the Earth's magnetosphere have demonstrated that the magnetotail current sheet can be supported by currents of anisotropic electron population. Strong electron currents are responsible for the formation of very thin (intense) current sheets playing the crucial role in stability of the Earth's magnetotail. We explore the properties of such thin current sheets with hot isotropic ions and cold anisotropic electrons. Decoupling of the motions of ions and electrons results in the generation of a polarization electric field. The distribution of the corresponding scalar potential is derived from the electron pressure balance and the quasi-neutrality condition. We find that electron pressure anisotropy is partially balanced by a field-aligned component of this polarization electric field. We propose a 2D model that describes a thin current sheet supported by currents of anisotropic electrons embedded in an ion-dominated current sheet. Current density profiles in our model agree well with THEMIS observations in the Earth's magnetotail.

  9. Effects of electron pressure anisotropy on current sheet configuration

    International Nuclear Information System (INIS)

    Artemyev, A. V.; Angelopoulos, V.; Runov, A.; Vasko, I. Y.

    2016-01-01

    Recent spacecraft observations in the Earth's magnetosphere have demonstrated that the magnetotail current sheet can be supported by currents of anisotropic electron population. Strong electron currents are responsible for the formation of very thin (intense) current sheets playing the crucial role in stability of the Earth's magnetotail. We explore the properties of such thin current sheets with hot isotropic ions and cold anisotropic electrons. Decoupling of the motions of ions and electrons results in the generation of a polarization electric field. The distribution of the corresponding scalar potential is derived from the electron pressure balance and the quasi-neutrality condition. We find that electron pressure anisotropy is partially balanced by a field-aligned component of this polarization electric field. We propose a 2D model that describes a thin current sheet supported by currents of anisotropic electrons embedded in an ion-dominated current sheet. Current density profiles in our model agree well with THEMIS observations in the Earth's magnetotail.

  10. THE USE OF COATINGS FOR HOT CORROSION AND EROSION PROTECTION IN TURBINE HOT SECTION COMPONENTS

    OpenAIRE

    Hayrettin AHLATCI

    1999-01-01

    High pressure turbine components are subjected to a wide variety of thermal and mechanical loading during service. In addition, the components are exposed to a highly oxidizing atmosphere which may contain contaminants such as sulphates, chlorides and sulphuorous gases along with erosive media. So the variety of surface coatings and deposition processes available for the protection of blade and vane components in gas turbines are summarised in this study. Coating types range from simple diff...

  11. Terahertz imaging and spectroscopy based on hot electron bolometer (HEB) heterodyne detection

    Science.gov (United States)

    Gerecht, Eyal; You, Lixing

    2008-02-01

    Imaging and spectroscopy at terahertz frequencies have great potential for healthcare, plasma diagnostics, and homeland security applications. Terahertz frequencies correspond to energy level transitions of important molecules in biology and astrophysics. Terahertz radiation (T-rays) can penetrate clothing and, to some extent, can also penetrate biological materials. Because of their shorter wavelengths, they offer higher spatial resolution than do microwaves or millimeter waves. We are developing hot electron bolometer (HEB) mixer receivers for heterodyne detection at terahertz frequencies. HEB detectors provide unprecedented sensitivity and spectral resolution at terahertz frequencies. We describe the development of a two-pixel focal plane array (FPA) based on HEB technology. Furthermore, we have demonstrated a fully automated, two-dimensional scanning, passive imaging system based on our HEB technology operating at 0.85 THz. Our high spectral resolution terahertz imager has a total system noise equivalent temperature difference (NEΔT) value of better than 0.5 K and a spatial resolution of a few millimeters. HEB technology is becoming the basis for advanced terahertz imaging and spectroscopic technologies for the study of biological and chemical agents over the entire terahertz spectrum.

  12. X-ray emitting hot plasma in solar active regions observed by the SphinX spectrometer

    Science.gov (United States)

    Miceli, M.; Reale, F.; Gburek, S.; Terzo, S.; Barbera, M.; Collura, A.; Sylwester, J.; Kowalinski, M.; Podgorski, P.; Gryciuk, M.

    2012-08-01

    Aims: The detection of very hot plasma in the quiescent corona is important for diagnosing heating mechanisms. The presence and the amount of such hot plasma is currently debated. The SphinX instrument on-board the CORONAS-PHOTON mission is sensitive to X-ray emission of energies well above 1 keV and provides the opportunity to detect the hot plasma component. Methods: We analysed the X-ray spectra of the solar corona collected by the SphinX spectrometer in May 2009 (when two active regions were present). We modelled the spectrum extracted from the whole Sun over a time window of 17 days in the 1.34-7 keV energy band by adopting the latest release of the APED database. Results: The SphinX broadband spectrum cannot be modelled by a single isothermal component of optically thin plasma and two components are necessary. In particular, the high statistical significance of the count rates and the accurate calibration of the spectrometer allowed us to detect a very hot component at ~7 million K with an emission measure of ~2.7 × 1044 cm-3. The X-ray emission from the hot plasma dominates the solar X-ray spectrum above 4 keV. We checked that this hot component is invariably present in both the high and low emission regimes, i.e. even excluding resolvable microflares. We also present and discuss the possibility of a non-thermal origin (which would be compatible with a weak contribution from thick-target bremsstrahlung) for this hard emission component. Conclusions: Our results support the nanoflare scenario and might confirm that a minor flaring activity is ever-present in the quiescent corona, as also inferred for the coronae of other stars.

  13. Extracting the temperature of hot carriers in time- and angle-resolved photoemission

    DEFF Research Database (Denmark)

    Ulstrup, Søren; Johannsen, Jens Christian; Grioni, Marco

    2014-01-01

    The interaction of light with a material’s electronic system creates an out-of-equilibrium (nonthermal) distribution of optically excited electrons. Non-equilibrium dynamics relaxes this distribution on an ultrafast timescale to a hot Fermi-Dirac distribution with a well-defined temperature......, we introduce a method that circumvents these difficulties and accurately extracts both the temperature and the position of the Fermi level for a hot carrier distribution by tracking the occupation statistics of the carriers measured in a TR-ARPES experiment...

  14. Electron heating caused by parametrically driven turbulence near the critical density

    International Nuclear Information System (INIS)

    Mizuno, K.; DeGroot, J.S.; Estabrook, K.G.

    1986-01-01

    Microwave-driven experiments and particle simulation calculations are presented that model s-polarized laser light incident on a pellet. In the microwave experiments, the incident microwaves are observed to decay into ion and electron waves near the critical density if the microwave power is above a well-defined threshold. Significant absorption, thermal electron heating, and hot electron generation are observed for microwave powers above a few times threshold. Strong absorption, strong profile modification, strongly heated hot electrons with a Maxwellian distribution, a hot-electron temperature that increases slowly with power, and a hot-electron density that is almost constant, are all observed in both the microwave experiments and simulation calculations for high powers. In addition, the thermal electrons are strongly heated for high powers in the microwave experiments

  15. Nonlinear electrostatic solitary waves in electron-positron plasmas

    Science.gov (United States)

    Lazarus, I. J.; Bharuthram, R.; Moolla, S.; Singh, S. V.; Lakhina, G. S.

    2016-02-01

    The generation of nonlinear electrostatic solitary waves (ESWs) is explored in a magnetized four component two-temperature electron-positron plasma. Fluid theory is used to derive a set of nonlinear equations for the ESWs, which propagate obliquely to an external magnetic field. The electric field structures are examined for various plasma parameters and are shown to yield sinusoidal, sawtooth and bipolar waveforms. It is found that an increase in the densities of the electrons and positrons strengthen the nonlinearity while the periodicity and nonlinearity of the wave increases as the cool-to-hot temperature ratio increases. Our results could be useful in understanding nonlinear propagation of waves in astrophysical environments and related laboratory experiments.

  16. Printed Electronics

    Science.gov (United States)

    Wade, Jessica; Hollis, Joseph Razzell; Wood, Sebastian

    2018-04-01

    The combination of printing technology with manufacturing electronic devices enables a new paradigm of printable electronics, where 'smart' functionality can be readily incorporated into almost any product at low cost. Over recent decades, rapid progress has been made in this field, which is now emerging into the industrial andcommercial realm. However, successful development and commercialisation on a large scale presents some significant technical challenges. For fully-printable electronic systems, all the component parts must be deposited from solutions (inks), requiring the development of new inorganic, organic and hybrid materials.A variety of traditional printing techniques are being explored and adapted forprinting these new materials in ways that result in the best performing electronicdevices. Whilst printed electronics research has initially focused on traditional typesof electronic device such as light-emitting diodes, transistors, and photovoltaics, it is increasingly apparent that a much wider range of applications can be realised. The soft and stretchable nature of printable materials makes them perfect candidates forbioelectronics, resulting in a wealth of research looking at biocompatible printable inks and biosensors. Regardless of application, the properties of printed electronicmaterials depend on the chemical structures, processing conditions, device architecture,and operational conditions, the complex inter-relationships of which aredriving ongoing research. We focus on three particular 'hot topics', where attention is currently focused: novel materials, characterisation techniques, and device stability. With progress advancing very rapidly, printed electronics is expected to grow over the next decade into a key technology with an enormous economic and social impact.

  17. Microsupercapacitors as miniaturized energy-storage components for on-chip electronics

    Science.gov (United States)

    Kyeremateng, Nana Amponsah; Brousse, Thierry; Pech, David

    2017-01-01

    The push towards miniaturized electronics calls for the development of miniaturized energy-storage components that can enable sustained, autonomous operation of electronic devices for applications such as wearable gadgets and wireless sensor networks. Microsupercapacitors have been targeted as a viable route for this purpose, because, though storing less energy than microbatteries, they can be charged and discharged much more rapidly and have an almost unlimited lifetime. In this Review, we discuss the progress and the prospects of integrated miniaturized supercapacitors. In particular, we discuss their power performances and emphasize the need of a three-dimensional design to boost their energy-storage capacity. This is obtainable, for example, through self-supported nanostructured electrodes. We also critically evaluate the performance metrics currently used in the literature to characterize microsupercapacitors and offer general guidelines to benchmark performances towards prospective applications.

  18. Solar 'hot spots' are still hot

    Science.gov (United States)

    Bai, Taeil

    1990-01-01

    Longitude distributions of solar flares are not random but show evidence for active zones (or hot spots) where flares are concentrated. According to a previous study, two hot spots in the northern hemisphere, which rotate with a synodic period of about 26.72 days, produced the majority of major flares, during solar cycles 20 and 21. The more prominent of these two hot spots is found to be still active during the rising part of cycle 22, producing the majority of northern hemisphere major flares. The synodic rotation period of this hot spot is 26.727 + or - 0.007 days. There is also evidence for hot spots in the southern hemisphere. Two hot spots separated by 180 deg are found to rotate with a period of 29.407 days, with one of them having persisted in the same locations during cycles 19-22 and the other, during cycles 20-22.

  19. Hot cell facilities for post irradiation examination

    International Nuclear Information System (INIS)

    Mishra, Prerna; Bhandekar, Anil; Pandit, K.M.; Dhotre, M.P.; Rath, B.N.; Nagaraju, P.; Dubey, J.S.; Mallik, G.K.; Singh, J.L.

    2017-01-01

    Reliable performance of nuclear fuels and critical core components has a large bearing on the economics of nuclear power and radiation safety of plant operating personnel. In view of this, Post Irradiation Examination (PIE) is periodically carried out on fuels and components to generate feedback information which is used by the designers, fabricators and the reactor operators to bring about changes for improved performance of the fuel and components. Examination of the fuel bundles has to be carried out inside hot cells due to their high radioactivity

  20. Third generation hybrid drive. Transmission-based integration of power electronics; Dritte Generation Hybridantrieb. Getriebenahe Integration der Leistungselektronik

    Energy Technology Data Exchange (ETDEWEB)

    Schoen, Wolfgang [ZF Friedrichshafen AG, Friedrichshafen (DE). Hybridantriebe (F und E); Lutz, Steffen [BMW AG, Muenchen (Germany); Hensler, Alexander [Technische Univ. Chemnitz (Germany); Munding, Andreas [Liebherr Elektronik GmbH, Lindau (Germany); Thoben, Markus [Infineon Technologies AG, Warstein (Germany); Zeidler, Dietmar [Kemet Electronics GmbH, Landsberg am Lech (Germany)

    2011-06-15

    The power electronics components in today's hybrid vehicles are situated at different places in the vehicle - till now far away from harsh and hot surroundings. In order to develop an integrated solution near the transmission, ZF and BMW launched the research project 'Electric components for active power transmissions' (EfA). On the basis of an eight-speed full hybrid transmission and together with Infineon, Kemet, Liebherr, and the University of Technology of Chemnitz, they are developing a power electronics unit, which facilitates doubling the power density while increasing the operating temperature. The project EfA will be concluded in June 2011. (orig.)

  1. Hot electron emission can lead to damping of optomechanical modes in core-shell Ag@TiO2 nanocubes

    DEFF Research Database (Denmark)

    Tamulevičius, Sigitas; Peckus, Domantas; Rong, Hongpan

    2017-01-01

    Interactions between light and metal nanostructures are mediated by collective excitations of free electrons called surface plasmons, which depend primarily on geometry and dielectric environment. Excitation with ultrafast pulses can excite optomechanical modes that modulate the volume and shape...... resonance is being lost to the TiO2 as hot carriers instead of coupling to the optomechanical mode. Analysis of both ultrafast decay and characterization of optomechanical modes provides a dual accounting method to track energy dissipation in hybrid metal-semiconductor nanosystems for plasmon-enhanced solar...

  2. Assessment of electronic component failure rates on the basis of experimental data

    International Nuclear Information System (INIS)

    Nitsch, R.

    1991-01-01

    Assessment and prediction of failure rates of electronic systems are made using experimental data derived from laboratory-scale tests or from the practice, as for instance from component failure rate statistics or component repair statistics. Some problems and uncertainties encountered in an evaluation of such field data are discussed in the paper. In order to establish a sound basis for comparative assessment of data from various sources, the items of comparison and the procedure in case of doubt have to be defined. The paper explains two standard methods proposed for practical failure rate definition. (orig.) [de

  3. Electron/electron acoustic instability

    International Nuclear Information System (INIS)

    Gary, S.P.

    1987-01-01

    The electron acoustic wave becomes a normal mode of an unmagnetized collisionless plasma in the presence of two electron components with similar densities, but strongly disparate temperatures. The characteristic frequency of this mode is the plasma frequency of the cooler electron component. If these two electron components have a relative drift speed several times the thermal speed of the cooler component, the electron/electron acoustic instability may arise. This paper describes the parametric dependences of the threshold drift speed and maximum growth rate of this instability, and compares these with the same properties of the electron/ion acoustic instability. Under the condition of zero current, the electron/ion acoustic instability typically has the lower threshold drift speed, so that observation of the electron/electron acoustic instability is a strong indication of the presence of an electrical current in the plasma

  4. Solar hot spots are still hot

    International Nuclear Information System (INIS)

    Bai, T.

    1990-01-01

    Longitude distributions of solar flares are not random but show evidence for active zones (or hot spots) where flares are concentrated. According to a previous study, two hot spots in the northern hemisphere, which rotate with a synodic period of about 26.72 days, produced the majority of major flares, during solar cycles 20 and 21. The more prominent of these two hot spots is found to be still active during the rising part of cycle 22, producing the majority of northern hemisphere major flares. The synodic rotation period of this hot spot is 26.727 + or - 0.007 days. There is also evidence for hot spots in the southern hemisphere. Two hot spots separated by 180 deg are found to rotate with a period of 29.407 days, with one of them having persisted in the same locations during cycles 19-22 and the other, during cycles 20-22. 14 refs

  5. Thermal tides on a hot Jupiter

    Directory of Open Access Journals (Sweden)

    Hsieh H.-F.

    2011-07-01

    Full Text Available Following the linear analysis laid out by Gu & Ogilvie 2009 (hereafter GO09, we investigate the dynamical response of a non-synchronized hot Jupiter to stellar irradiation. Besides the internal and Rossby waves considered by GO09, we study the Kelvin waves excited by the diurnal Fourier harmonic of the prograde stellar irradiation. We also present a 2-dimensional plot of internal waves excited by the semi-diurnal component of the stellar irradiation and postulate that thermal bulges may arise in a hot Jupiter. Whether our postulation is valid and is consistent with the recent results from Arras & Socrates (2009b requires further investigation.

  6. Techniques and devices developed by the CEA for hot cell and in-situ examinations of PWR components and PWR fuel assembliess after irradiation

    International Nuclear Information System (INIS)

    Van Craeynest, J.C.; Leseur, A.; Lhermenier, A.; Cytermann, R.

    1981-11-01

    Within the framework of the electro-nuclear development of the PWR system, the CEA has provided itself with facilities for developing techniques for analyzing assemblies, pins and fuels. These are examinations and tests on irradiated heads and assemblies with the aid of the Fuel Examination Module (FEM), of machining of assemblies and examinations in the Celimene hot laboratory or detailed examinations and analyses on fuel elements using eddy currents, the electronic microprobe and the Fisher ''permeascope'' which enables the outline of the oxide coat present on the cladding to be followed [fr

  7. Two-Dimensional Simulations of Electron Shock Ignition at the Megajoule Scale

    Science.gov (United States)

    Shang, W.; Betti, R.

    2016-10-01

    Shock ignition uses a late strong shock to ignite the hot spot of an inertial confinement fusion capsule. In the standard shock-ignition scheme, an ignitor shock is launched by the ablation pressure from a spike in laser intensity. Recent experiments on OMEGA have shown that focused beams with intensity up to 6 ×1015 W /cm2 can produce copious amounts of hot electrons. The hot electrons are produced by laser-plasma instabilities (LPI's) and can carry up to 15 % of the instantaneous laser power. Megajoule-scale targets will likely produce even more hot electrons because of the large plasma scale length. We show that it is possible to design ignition targets with low implosion velocities that can be shock ignited using LPI-generated hot electrons to obtain high energy gains. These designs are robust to low-mode asymmetries and they ignite even for highly distorted implosions. Electron shock ignition requires tens of kilojoules of hot electrons, which can only be produced on a large laser facility like the National Ignition Facility. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0001944.

  8. Experimental and numerical analyses of magnesium alloy hot workability

    Directory of Open Access Journals (Sweden)

    F. Abbassi

    2016-12-01

    Full Text Available Due to their hexagonal crystal structure, magnesium alloys have relatively low workability at room temperature. In this study, the hot workability behavior of cast-extruded AZ31B magnesium alloy is studied through hot compression testing, numerical modeling and microstructural analyses. Hot deformation tests are performed at temperatures of 250 °C to 400 °C under strain rates of 0.01 to 1.0 s−1. Transmission electron microscopy is used to reveal the presence of dynamic recrystallization (DRX, dynamic recovery (DRY, cracks and shear bands. To predict plastic instabilities during hot compression tests of AZ31B magnesium alloy, the authors use Johnson–Cook damage model in a 3D finite element simulation. The optimal hot workability of magnesium alloy is found at a temperature (T of 400 °C and strain rate (ε˙ of 0.01 s−1. Stability is found at a lower strain rate, and instability is found at a higher strain rate.

  9. The forming process of magnesium alloy for Japanese home electric components

    Energy Technology Data Exchange (ETDEWEB)

    Takara, A. [Matsushita Electric Industrial Co., Kadoma, Osaka (Japan); Higashi, K. [Osaka Prefecture Univ., Sakai, Osaka (Japan)

    2005-07-01

    Magnesium alloys have replaced resins as a material for the components of electronic products such as cell phone and notebook personal computer mainly, because of their lightness and rigidity. Thin walls, a complicated shape, and high appearance quality are all needed in the external parts. Die-casting and injection molding are the main method of manufacturing magnesium alloy parts. The optimal cast conditions and mold design have been investigated in order that a few defects such as surface cracks and mold cavities in casting parts would be reduced. Instead of cast, plastic forming technologies such as warm drawing and hot forging have been developed to form thinner walls and less defects. Plastic formability of magnesium alloy in hot working is dependent on a grain size of material. The material with fine grains has advantage of being formed at high strain rate. The characteristics of forming processes of magnesium parts for Japanese home electric appliances are compared in the viewpoint of quality, cost, and productivity. (orig.)

  10. Integration of remote refurbishment performed on ITER components

    Energy Technology Data Exchange (ETDEWEB)

    Dammann, A., E-mail: alexis.dammann@iter.org [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Antola, L. [AMEC, 31 Parc du Golf, CS 90519, 13596 Aix en Provence (France); Beaudoin, V. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Dremel, C. [Westinghouse, Electrique France/Astare, 122 Avenue de Hambourg, 13008 Marseille (France); Evrard, D. [SOGETI High Tech, 180 Rue René Descartes, 13851 Aix en Provence (France); Friconneau, J.P. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France); Lemée, A. [SOGETI High Tech, 180 Rue René Descartes, 13851 Aix en Provence (France); Levesy, B.; Pitcher, C.S. [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France)

    2015-10-15

    Highlights: • System engineering approach to consolidate requirements to modify the layout of the Hot Cell. • Illustration of the loop between requirement and design. • Verification process. - Abstract: Internal components of the ITER Tokamak are replaced and transferred to the Hot Cell by remote handling equipment. These components include port plugs, cryopumps, divertor cassettes, blanket modules, etc. They are brought to the refurbishment area of the ITER Hot Cell Building for cleaning and maintenance, using remote handling techniques. The ITER refurbishment area will be unique in the world, when considering combination of size, quantity of complex component to refurbish in presence of radiation, activated dust and tritium. The refurbishment process to integrate covers a number of workstations to perform specific remote operations fully covered by a mast on crane system. This paper describes the integration of the Refurbishment Area, explaining the functions, the methodology followed, some illustrations of trade-off and safety improvements.

  11. Investigation of Heat Sink Efficiency for Electronic Component Cooling Applications

    DEFF Research Database (Denmark)

    Staliulionis, Ž.; Zhang, Zhe; Pittini, Riccardo

    2014-01-01

    Research and optimisation of cooling of electronic components using heat sinks becomes increasingly important in modern industry. Numerical methods with experimental real-world verification are the main tools to evaluate efficiency of heat sinks or heat sink systems. Here the investigation...... of relatively simple heat sink application is performed using modeling based on finite element method, and also the potential of such analysis was demonstrated by real-world measurements and comparing obtained results. Thermal modeling was accomplished using finite element analysis software COMSOL and thermo...

  12. HOT 2015

    DEFF Research Database (Denmark)

    Hannibal, Sara Stefansen

    2016-01-01

    HOT samler og formidler 21 literacykyndiges bud på, hvad der er hot, og hvad der bør være hot inden for literacy – og deres begrundelser for disse bud.......HOT samler og formidler 21 literacykyndiges bud på, hvad der er hot, og hvad der bør være hot inden for literacy – og deres begrundelser for disse bud....

  13. The hot plasma environment at jupiter: ulysses results.

    Science.gov (United States)

    Lanzerotti, L J; Armstrong, T P; Gold, R E; Anderson, K A; Krimigis, S M; Lin, R P; Pick, M; Roelof, E C; Sarris, E T; Simnett, G M; Maclennan, C G; Choo, H T; Tappin, S J

    1992-09-11

    Measurements of the hot plasma environment during the Ulysses flyby of Jupiter have revealed several new discoveries related to this large rotating astrophysical system. The Jovian magnetosphere was found by Ulysses to be very extended, with the day-side magnetopause located at approximately 105 Jupiter radii. The heavy ion (sulfur, oxygen, and sodium) population in the day-side magnetosphere increased sharply at approximately 86 Jupiter radii. This is somewhat more extended than the "inner" magnetosphere boundary region identified by the Voyager hot plasma measurements. In the day-side magnetosphere, the ion fluxes have the anisotropy direction expected for corotation with the planet, with the magnitude of the anisotropy increasing when the spacecraft becomes more immersed in the hot plasma sheet. The relative abundances of sulfur, oxygen, and sodium to helium decreased somewhat with decreasing radial distance from the planet on the day-side, which suggests that the abundances of the Jupiter-derived species are dependent on latitude. In the dusk-side, high-latitude region, intense fluxes of counter-streaming ions and electrons were discovered from the edge of the plasma sheet to the dusk-side magnetopause. These beams of electrons and ions were found to be very tightly aligned with the magnetic field and to be superimposed on a time- and space-variable isotropic hot plasma background. The currents carried by the measured hot plasma particles are typically approximately 1.6 x 10(-4) microamperes per square meter or approximately 8 x 10(5) amperes per squared Jupiter radius throughout the high-latitude magnetosphere volume. It is likely that the intense particle beams discovered at high Jovian latitudes produce auroras in the polar caps of the planet.

  14. Possibilities and prospects of investigation of irradiated structural and fuel materials using scanning electron microscope PHILLIPS XL 30 ESEM-TMP installed in the hot cell

    International Nuclear Information System (INIS)

    Golovanov, V. N.; Novoselov, A.E.; Kuzmin, S.V.; Yakovlev, V. V.

    2005-01-01

    Scanning electron microscope Philips XL 30 ESEM - TMP with X-ray microanalysis system INCA has been installed at SSC RF RIAR. The microscope is placed in the hot cell. Monitoring and control system is installed in the operator's room. Irradiated specimens are supplied to the hot cell through the transport terminal and installed into the microscope by manipulators. Direct contact of the personnel with radioactive materials is impossible. In addition it is developed the system of remote placement of the irradiated specimens into the specimen chamber of microscope. The system includes a stage with three seats, holders for different types of specimens and equipment for their remote loading in the holders. (Author)

  15. Experimental comparison between different configurations of PCM based heat sinks for cooling electronic components

    International Nuclear Information System (INIS)

    Gharbi, Salma; Harmand, Souad; Jabrallah, Sadok Ben

    2015-01-01

    The thermal control of electronic components is aimed at ensuring their use in a temperature range compatible with their performances. This paper presents an experimental study of the behavior of phase change materials (PCMs) as the cooling system for electronic devices. Four configurations are used to control the increase in the system temperature: pure PCM, PCM in a silicone matrix, PCM in a graphite matrix and pure PCM in a system of fins. Thermo-physical properties of different PCMs are determined and found to be desirable for application in this study. Solid liquid interface visualization and temperature evolution are employed to understand the mechanism of heat transfer during the different stages. Results indicated that the inclusion of PCM can lower component increase temperature and extends twice the critical time of the heat sink. The use of Graphite matrix filled by PCM showed more improvement on system thermal performance than silicon matrix. Also, for the same fraction of copper, it was found that incorporating long copper fins with suitable spacing into PCM, can enhance heat distribution into PCM leading to longer remain component temperature below the critical limit. This work therefore shows that the combination of PCM and long, well-spaced fins presents an effective means for thermal control of electronic devices. - Highlights: • Study on thermal performance of different PCM based heat sink in electronic cooling. • Examination of heat transfer mechanism into heat sink for different conditions. • Graphite matrix shows more efficiency than silicon. • Inclusion PCM can reduce temperature increasing. • Heat sink with longer well spaced fins can extend longer the critical time

  16. Electronic zero-point fluctuation forces inside circuit components

    Science.gov (United States)

    Leonhardt, Ulf

    2018-01-01

    One of the most intriguing manifestations of quantum zero-point fluctuations are the van der Waals and Casimir forces, often associated with vacuum fluctuations of the electromagnetic field. We study generalized fluctuation potentials acting on internal degrees of freedom of components in electrical circuits. These electronic Casimir-like potentials are induced by the zero-point current fluctuations of any general conductive circuit. For realistic examples of an electromechanical capacitor and a superconducting qubit, our results reveal the possibility of tunable forces between the capacitor plates, or the level shifts of the qubit, respectively. Our analysis suggests an alternative route toward the exploration of Casimir-like fluctuation potentials, namely, by characterizing and measuring them as a function of parameters of the environment. These tunable potentials may be useful for future nanoelectromechanical and quantum technologies. PMID:29719863

  17. Electronic zero-point fluctuation forces inside circuit components.

    Science.gov (United States)

    Shahmoon, Ephraim; Leonhardt, Ulf

    2018-04-01

    One of the most intriguing manifestations of quantum zero-point fluctuations are the van der Waals and Casimir forces, often associated with vacuum fluctuations of the electromagnetic field. We study generalized fluctuation potentials acting on internal degrees of freedom of components in electrical circuits. These electronic Casimir-like potentials are induced by the zero-point current fluctuations of any general conductive circuit. For realistic examples of an electromechanical capacitor and a superconducting qubit, our results reveal the possibility of tunable forces between the capacitor plates, or the level shifts of the qubit, respectively. Our analysis suggests an alternative route toward the exploration of Casimir-like fluctuation potentials, namely, by characterizing and measuring them as a function of parameters of the environment. These tunable potentials may be useful for future nanoelectromechanical and quantum technologies.

  18. STIS observations of five hot white dwarfs

    OpenAIRE

    Bannister, N. P.; Barstow, M. A.; Holberg, J. B.; Bruhweiler, F. C.

    2000-01-01

    We present some early results from a study of five hot DA white dwarf stars, based on spectra obtained using STIS. All show multiple components in one or more of the strong resonance absorption lines typically associated with the stellar photosphere (e.g. C IV, Si IV, N V and O V). Possible relationships between the non-photospheric velocity components and the interstellar medium or local stellar environment, are investigated, including contributions from gravitational redshifting.

  19. Study of the survival of the electronic components of the EAR 650 (ILOK 1) aerosol activity monitors

    International Nuclear Information System (INIS)

    Morisset, Aurele; Sciorella, Guy; Meriaux, Pierre; Pagel, Marcel; Simiand, Stephane

    1977-04-01

    This study, based on operational results obtained on instruments used in different centres of the CEA, allows the evaluation of means and methods to be used for the survival of the electronic components of this equipment. The number of components necessary for assuring the maintenance of these equipments, and in particular the specification of replacement components for those components, which are no more manufactured, are given [fr

  20. Coupled energy-drift and force-balance equations for high-field hot-carrier transport

    International Nuclear Information System (INIS)

    Huang, Danhong; Alsing, P.M.; Apostolova, T.; Cardimona, D.A.

    2005-01-01

    Coupled energy-drift and force-balance equations that contain a frictional force for the center-of-mass motion of electrons are derived for hot-electron transport under a strong dc electric field. The frictional force is found to be related to the net rate of phonon emission, which takes away the momentum of a phonon from an electron during each phonon-emission event. The net rate of phonon emission is determined by the Boltzmann scattering equation, which depends on the distribution of electrons interacting with phonons. The work done by the frictional force is included into the energy-drift equation for the electron-relative scattering motion and is found to increase the thermal energy of the electrons. The importance of the hot-electron effect in the energy-drift term under a strong dc field is demonstrated in reducing the field-dependent drift velocity and mobility. The Doppler shift in the energy conservation of scattering electrons interacting with impurities and phonons is found to lead to an anisotropic distribution of electrons in the momentum space along the field direction. The importance of this anisotropic distribution is demonstrated through a comparison with the isotropic energy-balance equation, from which we find that defining a state-independent electron temperature becomes impossible. To the leading order, the energy-drift equation is linearized with a distribution function by expanding it into a Fokker-Planck-type equation, along with the expansions of both the force-balance equation and the Boltzmann scattering equation for hot phonons

  1. HotRegion: a database of predicted hot spot clusters.

    Science.gov (United States)

    Cukuroglu, Engin; Gursoy, Attila; Keskin, Ozlem

    2012-01-01

    Hot spots are energetically important residues at protein interfaces and they are not randomly distributed across the interface but rather clustered. These clustered hot spots form hot regions. Hot regions are important for the stability of protein complexes, as well as providing specificity to binding sites. We propose a database called HotRegion, which provides the hot region information of the interfaces by using predicted hot spot residues, and structural properties of these interface residues such as pair potentials of interface residues, accessible surface area (ASA) and relative ASA values of interface residues of both monomer and complex forms of proteins. Also, the 3D visualization of the interface and interactions among hot spot residues are provided. HotRegion is accessible at http://prism.ccbb.ku.edu.tr/hotregion.

  2. Action Memorandum for Decommissioning of TAN-607 Hot Shop Area

    Energy Technology Data Exchange (ETDEWEB)

    M. A. Pinzel

    2007-05-01

    The Department of Energy is documenting the selection of an alternative for the TAN-607 Hot Shop Area using a Comprehensive Environmental Response, Compensation, and Liability Act non-time-critical removal action (NTCRA). The scope of the removal action is limited to TAN-607 Hot Shop Area. An engineering evaluation/cost analysis (EE/CA) has assisted the Department of Energy Idaho Operations Office in identifuomg the most effective method for performing the decommissioning of this structure whose mission has ended. TAN-607 Hot Shop Area is located at Test Area North Technical Support Facility within the Idaho National Laboratory Site. The selected alternative consists of demolishing the TAN-607 aboveground structures and components, removing belowground noninert components (e.g. wood products), and removing the radiologically contaminated debris that does not meet remedial action objectives (RAOs), as defined in the Record of Decision Amendment for the V-Tanks and Explanation of Significant Differences for the PM-2A Tanks at Test Area North, Operable Unit 1-10.

  3. Prototype solar heating and hot water system

    Science.gov (United States)

    1977-01-01

    Progress is reported in the development of a solar heating and hot water system which uses a pyramidal optics solar concentrator for heating, and consists of the following subsystems: collector, control, transport, and site data acquisition. Improvements made in the components and subsystems are discussed.

  4. Archaeal Nitrification in Hot Springs

    Science.gov (United States)

    Richter, A.; Daims, H.; Reigstad, L.; Wanek, W.; Wagner, M.; Schleper, C.

    2006-12-01

    Biological nitrification, i.e. the aerobic conversion of ammonia to nitrate via nitrite, is a major component of the global nitrogen cycle. Until recently, it was thought that the ability to aerobically oxidize ammonia was confined to bacteria of the phylum Proteobacteria. However, it has recently been shown that Archaea of the phylum Crenarchaeota are also capable of ammonia oxidation. As many Crenarchaeota are thermophilic or hyperthermophilic, and at least some of them are capable of ammonia oxidation we speculated on the existence of (hyper)thermophilic ammonia-oxidizing archaea (AOA). Using PCR primers specifically targeting the archaeal ammonia monooxygenase (amoA) gene, we were indeed able to confirm the presence of such organisms in several hot springs in Reykjadalur, Iceland. These hot springs exhibited temperatures well above 80 °C and pH values ranging from 2.0 to 4.5. To proof that nitrification actually took place under these extreme conditions, we measured gross nitrification rates by the isotope pool dilution method; we added 15N-labelled nitrate to the mud and followed the dilution of the label by nitrate production from ammonium either in situ (incubation in the hot spring) or under controlled conditions in the laboratory (at 80 °C). The nitrification rates in the hot springs ranged from 0.79 to 2.22 mg nitrate-N per L of mud and day. Controls, in which microorganisms were killed before the incubations, demonstrated that the nitrification was of biological origin. Addition of ammonium increased the gross nitrification rate approximately 3-fold, indicating that the nitrification was ammonium limited under the conditions used. Collectively, our study provides evidence that (1) AOA are present in hot springs and (2) that they are actively nitrifying. These findings have major implications for our understanding of nitrogen cycling of hot environments.

  5. Seeded hot dark matter models with inflation

    Science.gov (United States)

    Gratsias, John; Scherrer, Robert J.; Steigman, Gary; Villumsen, Jens V.

    1993-01-01

    We examine massive neutrino (hot dark matter) models for large-scale structure in which the density perturbations are produced by randomly distributed relic seeds and by inflation. Power spectra, streaming velocities, and the Sachs-Wolfe quadrupole fluctuation are derived for this model. We find that the pure seeded hot dark matter model without inflation produces Sachs-Wolfe fluctuations far smaller than those seen by COBE. With the addition of inflationary perturbations, fluctuations consistent with COBE can be produced. The COBE results set the normalization of the inflationary component, which determines the large-scale (about 50/h Mpc) streaming velocities. The normalization of the seed power spectrum is a free parameter, which can be adjusted to obtain the desired fluctuations on small scales. The power spectra produced are very similar to those seen in mixed hot and cold dark matter models.

  6. Other components

    International Nuclear Information System (INIS)

    Anon.

    1993-01-01

    This chapter includes descriptions of electronic and mechanical components which do not merit a chapter to themselves. Other hardware requires mention because of particularly high tolerance or intolerance of exposure to radiation. A more systematic analysis of radiation responses of structures which are definable by material was given in section 3.8. The components discussed here are field effect transistors, transducers, temperature sensors, magnetic components, superconductors, mechanical sensors, and miscellaneous electronic components

  7. Introduction of hot cell facility in research center Rez - Poster

    International Nuclear Information System (INIS)

    Petrickova, A.; Srba, O.; Miklos, M.; Svoboda, P.

    2015-01-01

    This poster presents the hot cell facility which is being constructed as part of the SUSEN project at the Rez research center (Czech Republic). Within this project a new complex of 10 hot cells and one semi-hot cell will be built. There will be 8 gamma hot cells and 2 alpha hot cells. In each hot cell a hermetic, removable box made of stainless steel will home different type of devices. The hot cells and semi hot cell will be equipped with devices for processing samples (cutting, welding, drilling, machining) as well as equipment for testing (sample preparation area, stress testing machine, fatigue machine, electromechanical creep machine, high frequency resonance pulsator...) and equipment for studying material microstructure (nano-indenter with nano-scratch tester and scanning electron microscope). An autoclave with water loop, installed in a cell will allow mechanical testing in control environment of water, pressure and temperature. A scheme shows the equipment of each cell. This hot laboratory will be able to cover all the process to study radioactive materials: receiving the material, the preparation of the samples, mechanical testing and microstructure observation. Our hot cells will be close to the research nuclear reactor LVR-15 and new irradiation facility (high irradiation by cobalt source) is planned to be built within the SUSEN project

  8. Landing Gear Components Noise Study - PIV and Hot-Wire Measurements

    Science.gov (United States)

    Hutcheson, Florence V.; Burley, Casey L.; Stead, Daniel J.; Becker, Lawrence E.; Price, Jennifer L.

    2010-01-01

    PIV and hot-wire measurements of the wake flow from rods and bars are presented. The test models include rods of different diameters and cross sections and a rod juxtaposed to a plate. The latter is representative of the latch door that is attached to an aircraft landing gear when the gear is deployed, while the single and multiple rod configurations tested are representative of some of the various struts and cables configuration present on an aircraft landing gear. The test set up is described and the flow measurements are presented. The effect of model surface treatment and freestream turbulence on the spanwise coherence of the vortex shedding is studied for several rod and bar configurations.

  9. The magic of nanoplasmonics: from superhydrophobic and 3D suspended devices for SERS/TERS-like applications to hot-electrons based nanoscopy

    KAUST Repository

    Alabastri, A.; Toma, A.; Giugni, A.; Torre, B.; Malerba, M.; Miele, E.; De Angelis, F.; Liberale, Carlo; Das, Gobind; Di Fabrizio, Enzo M.; Proietti Zaccaria, R.

    2014-01-01

    The ability to confine light in small volumes, associated to low background signals, is an important technological achievement for a number of disciplines such as biology or electronics. In fact, decoupling the source position from the sample area allows an unprecedented sensitivity which can be exploited in different systems. The most direct implications are however related to either Surface Enhanced Raman Scattering (SERS) or Tip Enhanced Raman Scattering (TERS). Furthermore, while the combination with super-hydrophobic patterns can overcome the typical diffusion limit of sensors, focused surface plasmons decaying into hot electrons can be exploited to study the electronic properties of the sample by means of a Schottky junction. Within this paper these techniques will be briefly described and the key role played by both surface and localized plasmons will be highlighted. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  10. The magic of nanoplasmonics: from superhydrophobic and 3D suspended devices for SERS/TERS-like applications to hot-electrons based nanoscopy

    KAUST Repository

    Alabastri, A.

    2014-05-02

    The ability to confine light in small volumes, associated to low background signals, is an important technological achievement for a number of disciplines such as biology or electronics. In fact, decoupling the source position from the sample area allows an unprecedented sensitivity which can be exploited in different systems. The most direct implications are however related to either Surface Enhanced Raman Scattering (SERS) or Tip Enhanced Raman Scattering (TERS). Furthermore, while the combination with super-hydrophobic patterns can overcome the typical diffusion limit of sensors, focused surface plasmons decaying into hot electrons can be exploited to study the electronic properties of the sample by means of a Schottky junction. Within this paper these techniques will be briefly described and the key role played by both surface and localized plasmons will be highlighted. © (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

  11. Experimental and numerical investigation of heat dissipation from an electronic component in a closed enclosure

    Directory of Open Access Journals (Sweden)

    George Bobin Saji

    2018-01-01

    Full Text Available Intensifying electronic component power dissipation levels, shortening product design cycle times, and greater than before requirement for more compact and reliable electronic systems with greater functionality, has heightened the need for thermal design tools that enable accurate solutions to be generated and quickly assessed. The present numerical study aims at developing a computational tool in OpenFOAM that can predict the heat dissipation rate and temperature profile of any electronic component in operation. A suitable computational domain with defined aspect ratio is chosen. For analyzing, “buoyant Boussinesq Simple Foam“ solver available with OpenFOAM is used. It was modified for adapting to the investigation with specified initial and boundary conditions. The experimental setup was made with the dimensions taken up for numerical study. Thermocouples were calibrated and placed in specified locations. For different heat input, the temperatures are noted down at steady state and compared with results from the numerical study.

  12. Effects of radiations on electronic components - Course IN2P3, release 6

    International Nuclear Information System (INIS)

    2007-01-01

    As many off-the-shelf electronic components are now present onboard satellites, launchers and planes, this course proposes an overview of effects radiations can have on these components, notably in space applications. A first part proposes an overview of radiative environments, and more particularly presents the space radiative environment (solar wind, solar flares, cosmic radiation, radiation belts). It also presents the atmospheric and Earth radiative environment due to cosmic radiation, the alpha radiation (origin of particles, particle flow), the radiative environment within an accelerator. The second part addresses the effects of these radiative environments on electronic components, and the associated standards and tests. It addresses cumulative effects and proposes a detailed analysis of the effects of an ionizing dose on a MOS transistor, an analysis of the effects of ionising dose rate on a bipolar NPN or PNP vertical or lateral transistor, an analysis of the effects of atomic displacements, and a discussion of structure modifications. The next part describes various single events: the Single Event Upset (SEU) and the Multiple Bit Upset (MBU) in the case of a SRAM, the SEL (Single Event Latch-up) phenomenon, the SEGR (Single Event Gate Rupture) phenomenon in the case of a Power MOSFET, and the SEB (Single Event Burnout) phenomenon in the case of a Power MOSFET

  13. Microstructural characterization by electron backscatter diffraction of a hot worked Al-Cu-Mg alloy

    Energy Technology Data Exchange (ETDEWEB)

    Cepeda-Jimenez, C.M., E-mail: cm.cepeda@cenim.csic.es [Department of Physical Metallurgy, CENIM, CSIC, Av. Gregorio del Amo 8, 28040 Madrid (Spain); Hidalgo, P.; Carsi, M.; Ruano, O.A.; Carreno, F. [Department of Physical Metallurgy, CENIM, CSIC, Av. Gregorio del Amo 8, 28040 Madrid (Spain)

    2011-03-25

    Research highlights: {yields} The most favourable conditions for hot workability have been determined. {yields} EBSD was employed to characterize the obtained microtexture and microstructure. {yields} The Al 2024 alloy torsion tested at 408 deg. C and 2.1 s{sup -1} showed maximum ductility. {yields} Solid solution and fine precipitates favour a fine microstructure at 408 deg. C. {yields} The increase in test temperature to 467 deg. C produces a sharp decrease in ductility. - Abstract: Hot torsion tests to fracture to simulate thermomechanical processing were carried out on a solution-treated Al-Cu-Mg alloy (Al 2024-T351) at constant temperature. Torsion tests were conducted in the range 278-467 deg. C, and at two strain rates, 2.1 and 4.5 s{sup -1}. Electron backscatter diffraction (EBSD) was employed to characterize the microtexture and microstructure before and after testing. The microstructural evolution during torsion deformation at different temperatures and strain rate conditions determines the mechanical properties at room temperature of the Al 2024 alloy since grain refining, dynamic precipitation and precipitate coalescence occur during the torsion test. These mechanical properties were measured by Vickers microhardness tests. At 408 deg. C and 2.1 s{sup -1} the optimum combination of solid solution and incipient precipitation gives rise to maximum ductility and large fraction of fine and misoriented grains (f{sub HAB} = 54%). In contrast, the increase in test temperature to 467 deg. C produces a sharp decrease in ductility, attributed to the high proportion of alloying elements in solid solution. Both the stress-strain flow curves obtained by torsion tests and the final microstructures are a consequence of recovery phenomena and the dynamic nature of the precipitation process taking place during deformation.

  14. Microstructural characterization by electron backscatter diffraction of a hot worked Al-Cu-Mg alloy

    International Nuclear Information System (INIS)

    Cepeda-Jimenez, C.M.; Hidalgo, P.; Carsi, M.; Ruano, O.A.; Carreno, F.

    2011-01-01

    Research highlights: → The most favourable conditions for hot workability have been determined. → EBSD was employed to characterize the obtained microtexture and microstructure. → The Al 2024 alloy torsion tested at 408 deg. C and 2.1 s -1 showed maximum ductility. → Solid solution and fine precipitates favour a fine microstructure at 408 deg. C. → The increase in test temperature to 467 deg. C produces a sharp decrease in ductility. - Abstract: Hot torsion tests to fracture to simulate thermomechanical processing were carried out on a solution-treated Al-Cu-Mg alloy (Al 2024-T351) at constant temperature. Torsion tests were conducted in the range 278-467 deg. C, and at two strain rates, 2.1 and 4.5 s -1 . Electron backscatter diffraction (EBSD) was employed to characterize the microtexture and microstructure before and after testing. The microstructural evolution during torsion deformation at different temperatures and strain rate conditions determines the mechanical properties at room temperature of the Al 2024 alloy since grain refining, dynamic precipitation and precipitate coalescence occur during the torsion test. These mechanical properties were measured by Vickers microhardness tests. At 408 deg. C and 2.1 s -1 the optimum combination of solid solution and incipient precipitation gives rise to maximum ductility and large fraction of fine and misoriented grains (f HAB = 54%). In contrast, the increase in test temperature to 467 deg. C produces a sharp decrease in ductility, attributed to the high proportion of alloying elements in solid solution. Both the stress-strain flow curves obtained by torsion tests and the final microstructures are a consequence of recovery phenomena and the dynamic nature of the precipitation process taking place during deformation.

  15. Cold component flow in a two-component mirror machine

    International Nuclear Information System (INIS)

    Rognlien, T.D.

    1975-12-01

    Steady-state solutions are given for the flow characteristics along the magnetic field of the cold plasma component in a two-component mirror machine. The hot plasma component is represented by a fixed density profile. The fluid equations are used to describe the cold plasma, which is assumed to be generated in a localized region at one end of the machine. The ion flow speed, v/sub i/, is required to satisfy the Bohm sheath condition at the end walls, i.e., v/sub i/ greater than or equal to c/sub s/, where c/sub s/ is the ion-acoustic speed. For the case when the cold plasma density, n/sub c/, is much less than the hot plasma density, n/sub h/, the cold plasma is stagnant and does not penetrate through the machine in the zero temperature case. The effect of a finite temperature is to allow for the penetration of a small amount of cold plasma through the machine. For the density range n/sub c/ approximately n/sub h/, the flow solutions are asymmetric about the midplane and have v/sub i/ = c/sub s/ near the midplane. Finally, for n/sub c/ much greater than n/sub h/, the solutions become symmetric about the midplane and approach the Lee--McNamara type solutions with v/sub i/ = c/sub s/ near the mirror throats

  16. Solar Hot Water Heater

    Science.gov (United States)

    1978-01-01

    The solar panels pictured below, mounted on a Moscow, Idaho home, are part of a domestic hot water heating system capable of providing up to 100 percent of home or small business hot water needs. Produced by Lennox Industries Inc., Marshalltown, Iowa, the panels are commercial versions of a collector co-developed by NASA. In an effort to conserve energy, NASA has installed solar collectors at a number of its own facilities and is conducting research to develop the most efficient systems. Lewis Research Center teamed with Honeywell Inc., Minneapolis, Minnesota to develop the flat plate collector shown. Key to the collector's efficiency is black chrome coating on the plate developed for use on spacecraft solar cells, the coating prevents sun heat from "reradiating," or escaping outward. The design proved the most effective heat absorber among 23 different types of collectors evaluated in a Lewis test program. The Lennox solar domestic hot water heating system has three main components: the array of collectors, a "solar module" (blue unit pictured) and a conventional water heater. A fluid-ethylene glycol and water-is circulated through the collectors to absorb solar heat. The fluid is then piped to a double-walled jacket around a water tank within the solar module.

  17. Biomediated Precipitation of Calcium Carbonate in a Slightly Acidic Hot Spring

    Science.gov (United States)

    Jiang, L.

    2015-12-01

    A slightly acidic hot spring named "Female Tower" (T=73.5 °C, pH=6.64) is located in the Jifei Geothermal Field, Yunnan Province, Southwest China. The precipitates in the hot spring are composed of large amounts of calcite, aragonite, and sulfur. Scanning electron microscopy (SEM) analyses revealed that the microbial mats were formed of various coccoid, rod-shaped, and filamentous microbes. Transmission electron microscopy (TEM) showed that the intracellular sulfur granules were commonly associated with these microbes. A culture-independent molecular phylogenetic analysis demonstrated that the majority of the bacteria in the spring were sulfur-oxidizing bacteria. In the spring water, H2S concentration was up to 60 ppm, while SO42- concentration was only about 10 ppm. We speculated that H2S might be utilized by sulfur-oxidizing bacteria in this hot spring water, leading to the intracellular formation of sulfur granules. In the meantime, this reaction increased the pH in the micron-scale microdomains, which fostered the precipitation of calcium carbonate in the microbial mats. The results of this study indicated that the sulfur-oxidizing bacteria could play an important role in calcium carbonate precipitation in slightly acidic hot spring environments.

  18. Plasma density profiles and finite bandwidth effects on electron heating

    International Nuclear Information System (INIS)

    Spielman, R.B.; Mizuno, K.; DeGroot, J.S.; Bollen, W.M.; Woo, W.

    1980-01-01

    Intense, p-polarized microwaves are incident on an inhomogeneous plasma in a cylindrical waveguide. Microwaves are mainly absorbed by resonant absorption near the critical surface (where the plasma frequency, ω/sub pe/, equals the microwave frequency, ω/sub o/). The localized plasma waves strongly modify the plasma density. Step-plateau density profiles or a cavity are created depending on the plasma flow speed. Hot electron production is strongly affected by the microwave bandwidth. The hot electron temperature varies as T/sub H/ is proportional to (Δ ω/ω) -0 25 . As the hot electron temperature decreases with increasing driver bandwidth, the hot electron density increases. This increase is such that the heat flux into the overdense region (Q is proportional to eta/sub H/T/sub H/ 3 2 ) is nearly constant

  19. The new generations of power components will depend on neutron and/or electron bombardment techniques

    International Nuclear Information System (INIS)

    Lilen, H.

    1976-01-01

    Neutron and electron bombardment techniques for materials doping, newly introduced in the fabrication of power semiconductor components: diodes, transistors, thyristors, and triacs are briefly outlined. A neutron bombardment of high purity silicon results in a short-lived 31 Si isotope (from 30 Si) decaying into 31 P. The phosphorus with its five peripheral electrons induces a negative doping (N), and the neutron technique gives a homogeneous doping. Furthermore, silicon bombardment with 1 to 2MeV electrons induces micro-ruptures in the lattice, that act as recombination traps reducing carrier lifetimes. Consequently, gold diffusion techniques can be replaced by electron bombardment with a gain in controlling carrier lifetimes [fr

  20. The Impact of Ceramic Shell Strength on Hot Tearing during Investment Casting

    International Nuclear Information System (INIS)

    Norouzi, Saeid; Farhangi, Hassan

    2011-01-01

    The effect of ceramic shell strength on hot tearing susceptibility during solidification was inspected practicing investment casting of the cobalt-base superalloy samples with the same casting conditions, but different ceramic shell systems. Results showed that the lower the ceramic shell strength upon using polymer additives, the lower the hindered contraction rate, and the lower the hindered contraction rate, the smaller the hot tearing tendency. Optical microscopy and electron microscopy scanning revealed that the hot tear propagated along the last solidified interdendritic phase, and that the hot tear surface had two major modes: 1) the ductile region in the outer layer; and 2) the inner region of liquid embrittlement.

  1. Hot plasma parameters in Neptune's magnetosphere

    International Nuclear Information System (INIS)

    Krimigis, S.M.; Mauk, B.H.; Cheng, A.F.; Keath, E.P.; Kane, M.; Armstrong, T.P.; Gloeckler, G.; Lanzerotti, L.J.

    1990-01-01

    Energy spectra of energetic protons and electrons (E p approx-gt 28 keV, E e approx-gt 22 keV, respectively) obtained with the Low Energy Charged Particle (LECP) instrument during the Voyager 2 encounter with Neptune on August 24-25, 1989 are presented. The proton spectral form was a power law (dj/dE = KE -γ ), outside the orbit of Triton (∼14.3 R N ); inside that distance, it was found to be a hot (kT ≅ 60 keV) Maxwellian distribution. Such distributions, observed in other planets as well, have yet to be explained theoretically. Similarly, the electron spectral form changed from a simple power law outside Triton to a two-slope power law with a high energy tail inside. Intensity and spectral features in both proton and electron fluxes were identified in association with the crossings of the Triton and 1989 N1 L-shells, but these features do not occur simultaneously in both species. Such signatures were manifested by relative peaks in both kT and γ spectral indices. Peak proton pressures of ∼2x10 -9 dynes cm -2 , and β ∼ 0.2 were measured at successive magnetic equatorial crossings, both inbound and outbound. These parameters show Neptune's magnetosphere to be relatively undistorted by hot plasma loading, similar to that of Uranus and unlike those of Saturn and Jupiter. Trapped electron fluxes at Neptune, as at Uranus, exceed the whistler mode stably trapped flux limit. Whistler-induced pitch angle scattering of energetic electrons in the radiation belts can yield a precipitating energy flux sufficient to drive Neptune's aurora

  2. Electron-cyclotron heating in the Constance 2 mirror experiment

    Energy Technology Data Exchange (ETDEWEB)

    Mauel, Michael E.

    1982-09-01

    Electron cyclotron heating of a highly-ionized plasma in mirror geometry is investigated. The experimental diagnosis of the electron energy distribution and the comparison of the results of this diagnosis with a two dimensional, time-dependent Fokker-Planck simulation are accomplished in four steps. (1) First, the power balance of the heated and unheated Constance 2 plasma is analyzed experimentally. It is concluded that the heated electrons escape the mirror at a rate dominated by a combination of the influx of cool electrons from outside the mirror and the increased loss rate of the ions. (2) The microwave parameters at the resonance zones are then calculated by cold-plasma ray tracing. High N/sub parallel/ waves are launched and for these waves, strong first-pass absorption is predicted. The absorption strength is qualitatively checked in the experiment by surrounding the plasma with non-reflecting liners. (3) A simplified quasilinear theory including the effect of N/sub parallel/ is developed to model the electrons. An analytic expression is derived for the RF-induced pump-out of the magnetically-confined warm electrons. Results of the Fokker-Planck simulations show the development of the electron energy distribution for several plasma conditions and verify the scaling of the analytic expression for RF-induced diffusion into the loss cone. (4) Sample x-ray and endloss data are presented, and the overall comparison between the simulation and experiment is discussed. The x-ray signals indicate that, for greater RF power, the hot electrondensity increases more rapidly than its temperature. The time history of the endloss data, illustrating RF-enhancement, suggests the predicted scaling for warm-electron pump-out. Finally, a comparison between the measured and predicted energy distribution shows that the bulk, warm and hot components of the heated Constance 2 electrons are indeed reproduced by the simulation.

  3. Electron-cyclotron heating in the Constance 2 mirror experiment

    International Nuclear Information System (INIS)

    Mauel, M.E.

    1982-09-01

    Electron cyclotron heating of a highly-ionized plasma in mirror geometry is investigated. The experimental diagnosis of the electron energy distribution and the comparison of the results of this diagnosis with a two dimensional, time-dependent Fokker-Planck simulation are accomplished in four steps. (1) First, the power balance of the heated and unheated Constance 2 plasma is analyzed experimentally. It is concluded that the heated electrons escape the mirror at a rate dominated by a combination of the influx of cool electrons from outside the mirror and the increased loss rate of the ions. (2) The microwave parameters at the resonance zones are then calculated by cold-plasma ray tracing. High N/sub parallel/ waves are launched and for these waves, strong first-pass absorption is predicted. The absorption strength is qualitatively checked in the experiment by surrounding the plasma with non-reflecting liners. (3) A simplified quasilinear theory including the effect of N/sub parallel/ is developed to model the electrons. An analytic expression is derived for the RF-induced pump-out of the magnetically-confined warm electrons. Results of the Fokker-Planck simulations show the development of the electron energy distribution for several plasma conditions and verify the scaling of the analytic expression for RF-induced diffusion into the loss cone. (4) Sample x-ray and endloss data are presented, and the overall comparison between the simulation and experiment is discussed. The x-ray signals indicate that, for greater RF power, the hot electrondensity increases more rapidly than its temperature. The time history of the endloss data, illustrating RF-enhancement, suggests the predicted scaling for warm-electron pump-out. Finally, a comparison between the measured and predicted energy distribution shows that the bulk, warm and hot components of the heated Constance 2 electrons are indeed reproduced by the simulation

  4. Effect of hot-dip galvanizing processes on the microstructure and mechanical properties of 600-MPa hot-dip galvanized dual-phase steel

    Science.gov (United States)

    Kuang, Chun-fu; Zheng, Zhi-wang; Wang, Min-li; Xu, Quan; Zhang, Shen-gen

    2017-12-01

    A C-Mn dual-phase steel was soaked at 800°C for 90 s and then either rapidly cooled to 450°C and held for 30 s (process A) or rapidly cooled to 350°C and then reheated to 450°C (process B) to simulate the hot-dip galvanizing process. The influence of the hot-dip galvanizing process on the microstructure and mechanical properties of 600-MPa hot-dip galvanized dual-phase steel (DP600) was investigated using optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and tensile tests. The results showed that, in the case of process A, the microstructure of DP600 was composed of ferrite, martensite, and a small amount of bainite. The granular bainite was formed in the hot-dip galvanizing stage, and martensite islands were formed in the final cooling stage after hot-dip galvanizing. By contrast, in the case of process B, the microstructure of the DP600 was composed of ferrite, martensite, bainite, and cementite. In addition, compared with the yield strength (YS) of the DP600 annealed by process A, that for the DP600 annealed by process B increased by approximately 50 MPa because of the tempering of the martensite formed during rapid cooling. The work-hardening coefficient ( n value) of the DP600 steel annealed by process B clearly decreased because the increase of the YS affected the computation result for the n value. However, the ultimate tensile strength (UTS) and elongation ( A 80) of the DP600 annealed by process B exhibited less variation compared with those of the DP600 annealed by process A. Therefore, DP600 with excellent comprehensive mechanical properties (YS = 362 MPa, UTS = 638 MPa, A 80 = 24.3%, n = 0.17) was obtained via process A.

  5. Modelling the Cast Component Weight in Hot Chamber Die Casting using Combined Taguchi and Buckingham's π Approach

    Science.gov (United States)

    Singh, Rupinder

    2018-02-01

    Hot chamber (HC) die casting process is one of the most widely used commercial processes for the casting of low temperature metals and alloys. This process gives near-net shape product with high dimensional accuracy. However in actual field environment the best settings of input parameters is often conflicting as the shape and size of the casting changes and one have to trade off among various output parameters like hardness, dimensional accuracy, casting defects, microstructure etc. So for online inspection of the cast components properties (without affecting the production line) the weight measurement has been established as one of the cost effective method (as the difference in weight of sound and unsound casting reflects the possible casting defects) in field environment. In the present work at first stage the effect of three input process parameters (namely: pressure at 2nd phase in HC die casting; metal pouring temperature and die opening time) has been studied for optimizing the cast component weight `W' as output parameter in form of macro model based upon Taguchi L9 OA. After this Buckingham's π approach has been applied on Taguchi based macro model for the development of micro model. This study highlights the Taguchi-Buckingham based combined approach as a case study (for conversion of macro model into micro model) by identification of optimum levels of input parameters (based on Taguchi approach) and development of mathematical model (based on Buckingham's π approach). Finally developed mathematical model can be used for predicting W in HC die casting process with more flexibility. The results of study highlights second degree polynomial equation for predicting cast component weight in HC die casting and suggest that pressure at 2nd stage is one of the most contributing factors for controlling the casting defect/weight of casting.

  6. Hawking radiation of Dirac particles in the hot NUT-Kerr-Newman spacetime

    International Nuclear Information System (INIS)

    Ahmed, M.

    1991-01-01

    The Hawking radiation of charged Dirac particles on the horizons of the hot NUT-Kerr-Newman spacetime is studied in this paper. To this end, we obtain the radial decoupled Dirac equation for the electron in the hot NUT-Kerr-Newman spacetime. Next we solve the Dirac equation near the horizons. Finally, by analytic continuation, the Hawking thermal spectrum formula of Dirac particles is obtained. The problem of the Hawking evaporation of Dirac particles in the hot NUT-Kerr-Newman background is thus solved. (orig.)

  7. Hot stage nanoindentation in multi-component Al-Ni-Si alloys: Experiment and simulation

    Energy Technology Data Exchange (ETDEWEB)

    Richter, A. [Institute of Polymer Technology and Materials Engineering, Loughborough University, Loughborough LE11 3TU (United Kingdom); Department of Engineering, University of Applied Sciences Wildau (Berlin), Bahnhofstrasse 1, Wildau 15745 (Germany)], E-mail: asta.richter@tfh-wildau.de; Chen, C.-L. [Institute of Polymer Technology and Materials Engineering, Loughborough University, Loughborough LE11 3TU (United Kingdom); Smith, R.; McGee, E. [Department of Mathematical Sciences, Loughborough University, Loughborough LE11 3TU (United Kingdom); Thomson, R.C. [Institute of Polymer Technology and Materials Engineering, Loughborough University, Loughborough LE11 3TU (United Kingdom); Kenny, S.D. [Department of Mathematical Sciences, Loughborough University, Loughborough LE11 3TU (United Kingdom)

    2008-10-25

    The mechanical properties of individually pure and intermetallic phases of typical Al-Ni-Si piston alloys are investigated at different temperatures using hot stage nanoindentation. The hardness and the indentation modulus of a number of phases are determined at room temperature, 500 K and 650 K. Both, hardness and reduced modulus drop with increasing temperature in different ratios for the various phases. Increasing Ni content in the grains improves the mechanical stability of the material at elevated temperatures in general. The indentation patterns are studied using atomic force microscopy with particular reference to the indentation depths and pile-up effects. Site-specific samples from the material surrounding the nanoindents are prepared using a focussed ion beam field emission gun for examination in the transmission electron microscope. This allows direct observation of material changes as a result of the indentation process in the different phases within the alloy system. Corresponding linked atomistic finite element calculations have been carried out for Si and Ni-Al systems as a function of increasing Ni content at various temperatures. The results show only a small difference in the mechanical behaviour of Si between 300 K and 650 K as observed in the experiments. Large differences for Al at both temperatures studied result in an increase of plasticity with rising temperature and atomic motion that changes from slip in well-defined planes to a viscous fluid-like behaviour. The formation of dislocations and slip bands during indentation for the Ni-Al systems is studied.

  8. Electron-attachment processes

    International Nuclear Information System (INIS)

    Christophorou, L.G.; McCorkle, D.L.; Christodoulides, A.A.

    1982-01-01

    Topics covered include: (1) modes of production of negative ions, (2) techniques for the study of electron attachment processes, (3) dissociative electron attachment to ground-state molecules, (4) dissociative electron attachment to hot molecules (effects of temperature on dissociative electron attachment), (5) molecular parent negative ions, and (6) negative ions formed by ion-pair processes and by collisions of molecules with ground state and Rydberg atoms

  9. Solar system for domestic hot water and space heating

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, W. [Arbeitsgemeinschaf Erneubare Energie, Gleisdorf (Austria)

    1997-12-31

    The solar thermal markets, different types of solar systems for hot water and space heating, the dimensioning and the components of solar heating systems, the properties of the systems are reviewed in this presentation

  10. Solar system for domestic hot water and space heating

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, W [Arbeitsgemeinschaf Erneubare Energie, Gleisdorf (Austria)

    1998-12-31

    The solar thermal markets, different types of solar systems for hot water and space heating, the dimensioning and the components of solar heating systems, the properties of the systems are reviewed in this presentation

  11. Effects of nonextensivity on the electron-acoustic solitary structures in a magnetized electron−positron−ion plasma

    Energy Technology Data Exchange (ETDEWEB)

    Rafat, A., E-mail: rafat.plasma@gmail.com; Rahman, M. M.; Alam, M. S.; Mamun, A. A. [Jahangirnagar University, Department of Physics (Bangladesh)

    2016-08-15

    Obliquely propagating electron-acoustic solitary waves (EASWs) in a magnetized electron−positron−ion plasma (containing nonextensive hot electrons and positrons, inertial cold electrons, and immobile positive ions) are precisely investigated by deriving the Zakharov–Kuznetsov equation. It is found that the basic features (viz. polarity, amplitude, width, phase speed, etc.) of the EASWs are significantly modified by the effects of the external magnetic field, obliqueness of the system, nonextensivity of hot positrons and electrons, ratio of the hot electron temperature to the hot positron temperature, and ratio of the cold electron number density to the hot positron number density. The findings of our results can be employed in understanding the localized electrostatic structures and the characteristics of EASWs in various astrophysical plasmas.

  12. The development on electric discharge machine for hot cell usage

    International Nuclear Information System (INIS)

    Ahn, Sang Bok; Kim, Young Suk; Park, Dae Kyu; Choo, Yong Sun; Oh, Wan Ho

    1998-06-01

    The electric discharge machine(EDM) was developed for hot cell usages in IMEF. This machine will be used to fabricate specimen directly from irradiated components from NPP's. The detailed contents are as follows; 1. Outline of electric discharge machine 2. Specimen shape to be fabricated by EDM 3. Technical specification to manufacture EDM 4. Installation EDM in hot cell 5. Optimum discharge conditions to fabricate specimens from CANDU tube. (author). 4 tabs., 20 figs

  13. Long-term effects as the cause of failure in electronic components

    International Nuclear Information System (INIS)

    Renz, H.; Kreichgauer, H.

    1989-01-01

    After a brief presentation of the utilisation properties of electronic components, their failure rates are discussed with particular reference to the socalled bath-tub curve. The main emphasis is on the construction and manufacture of integrated circuits and the possible types and causes of failure arising from the individual manufacturing stages (layout faults, internal corrosion, masking and etching errors, leakage currents, inadequate heat removal, etc.). A technical insurance assessment is then provided of the long-term failures associated with technological matters. (orig.) [de

  14. GfW-handbook for data compilation of irradiation tested electronic components

    International Nuclear Information System (INIS)

    Wulf, F.; Braeunig, D.; Gaebler, W.

    1981-06-01

    The present 2. edition of the Data Compilation of Irradiation Tested Electronic Components represents a continuation of the 1. edition and is published as a loose-leaf handbook. In addition to the 190 reports provided in the 1. issue the present handbook contains further 44 test reports of currently used semiconductor devices in a comprehensive but easily to handle graphical and tabular presentation. Statistical values are given in order to facilitate the parts life time evaluation in a radiative environment. (orig.) [de

  15. Selective Electron Beam Manufacturing of Ti-6Al-4V Strips: Effect of Build Orientation, Columnar Grain Orientation, and Hot Isostatic Pressing on Tensile Properties

    Science.gov (United States)

    Wang, J.; Tang, H. P.; Yang, K.; Liu, N.; Jia, L.; Qian, M.

    2018-03-01

    Many novel designs for additive manufacturing (AM) contain thin-walled (≤ 3 mm) sections in different orientations. Selective electron beam melting (SEBM) is particularly suited to AM of such thin-walled titanium components because of its high preheating temperature and high vacuum. However, experimental data on SEBM of Ti-6Al-4V thin sections remains scarce because of the difficulty and high cost of producing long, thin and smooth strip tensile specimens (see Fig. 1). In this study, 80 SEBM Ti-6Al-4V strips (180 mm long, 42 mm wide, 3 mm thick) were built both vertically (V-strips) and horizontally (H-strips). Their density, microstructure and tensile properties were investigated. The V-strips showed clearly higher tensile strengths but lower elongation than the H-strips. Hot isostatic pressing (HIP) produced the same lamellar α-β microstructures in terms of the average α-lath thickness in both types of strips. The retained prior-β columnar grain boundaries after HIP showed no measurable influence on the tensile properties, irrespective of their length and orientation, because of the formation of randomly distributed fine α-laths.[Figure not available: see fulltext.

  16. Hot deformation behavior of delta-processed superalloy 718

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y., E-mail: wangyanhit@yahoo.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); School of Aeronautics and Astronautics, Central South University, Changsha 410083 (China); Shao, W.Z.; Zhen, L.; Zhang, B.Y. [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

    2011-03-25

    Research highlights: {yields} The peak stress for hot deformation can be described by the Z parameter. {yields} The grain size of DRX was inversely proportional to the Z parameter. {yields} The dissolution of {delta} phases was greatly accelerated under hot deformation. {yields}The {delta} phase stimulated nucleation can serve as the main DRX mechanism. - Abstract: Flow stress behavior and microstructures during hot compression of delta-processed superalloy 718 at temperatures from 950 to 1100 deg. C with strain rates of 10{sup -3} to 1 s{sup -1} were investigated by optical microscopy (OM), electron backscatter diffraction (EBSD) technique and transmission electron microscopy (TEM). The relationship between the peak stress and the deformation conditions can be expressed by a hyperbolic-sine type equation. The activation energy for the delta-processed superalloy 718 is determined to be 467 kJ/mol. The change of the dominant deformation mechanisms leads to the decrease of stress exponent and the increase of activation energy with increasing temperature. The dynamically recrystallized grain size is inversely proportional to the Zener-Hollomon (Z) parameter. It is found that the dissolution rate of {delta} phases under hot deformation conditions is much faster than that under static conditions. Dislocation, vacancy and curvature play important roles in the dissolution of {delta} phases. The main nucleation mechanisms of dynamic recrystallization (DRX) for the delta-processed superalloy 718 include the bulging of original grain boundaries and the {delta} phase stimulated DRX nucleation, which is closely related to the dissolution behavior of {delta} phases under certain deformation conditions.

  17. The effects of polymers' visco-elastoplastic properties on the micro cavities filling step of hot embossing process

    Science.gov (United States)

    Cheng, Gang; Barrière, Thierry

    2018-05-01

    The hot embossing process has been widely used in the manufacturing of polymer components, especially for the fabrication of micro or nano components. The significant advantage of the hot embossing process compared to the traditional injection moulding process is the excellent effective filling ratio for the high aspect ratio components and large surface structural components. The lack of material behavior modeling and numerical simulation limits the further development the hot embossing process, especially at the micro and nano scales. In this paper, a visco-elastoplastic behavior law has been proposed to describe the amorphous thermoplastic polymer mechanical properties in the hot embossing processing temperature range, which is lightly above their glass transition temperature. Uniaxial compression tests have been carried out in order to investigate the amorphous thermoplastic polymers properties. The material parameters in the visco-elastoplastic model have been identified according to the experimental results. A 3D numerical model has been created in the simulation software, which is based on the finite element method. The numerical simulation of the filling step of the hot embossing process has been effectuated by taking into account the viscous, elastic and plastic behaviors of thermoplastic polymers. The micro hot embossing process has been carried out using horizontal injection compression moulding equipment. A complete compression mould tool, equipped with the heating system, the cooling system, the ejection system and the vacuum system, has been designed and elaborated for this research work. The microfluidic devices based on the amorphous thermoplastic polymers have been successfully elaborated by hot embossing process. Proper agreement between the numerical simulation and the experimental elaboration has been obtained.

  18. Fatigue life estimation considering welding residual stress and hot-spot stress of welded components

    International Nuclear Information System (INIS)

    Han, S. H.; Lee, T. K.; Shin, B. C.

    2002-01-01

    The fatigue life of welded joints is sensitive to welding residual stress and complexity of their geometric shapes. To predict the fatigue life more reasonably, the effects of welding residual stress and its relaxation have to be considered quantitatively which are equivalent to mean stress by external loads. The hot-spot stress concept should be also adopted which can be reduce the dependence of fatigue strengths for various welding details. Considering the factors mentioned above, a fatigue life prediction model using the modified Goodman's diagram was proposed. In this model, an equivalent stress was introduced which are composed of the mean stress based on the hot-spot stress concept and the relaxed welding residual stress. From the verification of the proposed model to real welding details, it is confirmed that this model can be applied to predict reasonably their fatigue lives

  19. (RN) pair production by photons in a hot Maxwellian plasma

    International Nuclear Information System (INIS)

    Haug, E.

    2004-01-01

    The production of electron-positron pairs by photons in the Coulomb Field of electrons and positrons (triplet production) in hot thermal plasmas is investigated. The pair production rate for this process is calculated as a function of the photon energy and compared with the rate of photon-nucleus pair production for semi-relativistic and relativistic plasma temperatures. (author)

  20. Application of powder metallurgy and hot rolling processes for manufacturing aluminum/alumina composite strips

    Energy Technology Data Exchange (ETDEWEB)

    Zabihi, Majed, E-mail: m.zabihi@ma.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Toroghinejad, Mohammad Reza, E-mail: toroghi@cc.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of); Shafyei, Ali, E-mail: shafyei@cc.iut.ac.ir [Department of Materials Engineering, Isfahan University of Technology, Isfahan 84156-83111 (Iran, Islamic Republic of)

    2013-01-10

    In this study, aluminum matrix composites (AMC) with 2, 4, 6 and 10 wt% alumina were produced using powder metallurgy (PM), mechanical milling (MM) and vacuum hot pressing (VHP) techniques; then, this was followed by the hot-rolling process. During hot rolling, AMCs with 6 and 10 wt% Al{sub 2}O{sub 3} were fractured whereas strip composites with 2 and 4 wt% Al{sub 2}O{sub 3} were produced successfully. Microstructure and mechanical properties of the samples were investigated by optical and scanning electron microscopes and tensile and hardness tests, respectively. Microscopic evaluations of the hot-rolled composites showed a uniform distribution of alumina particles in the aluminum matrix. It was found that with increasing alumina content in the matrix, tensile strength (TS) and hardness increased and the percentage of elongation also decreased. Scanning electron microscope (SEM) was used to investigate aluminum/alumina interfaces and fracture surfaces of the hot rolled specimens after tensile test. SEM observations demonstrated that the failure mode in the hot-rolled Al-2 wt% Al{sub 2}O{sub 3} composite strips is a typical ductile fracture, while the failure mode was shear ductile fracture with more flat surfaces in Al-4 wt% Al{sub 2}O{sub 3} strips.