WorldWideScience

Sample records for plasma impurities

  1. Impurity-induced divertor plasma oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Smirnov, R. D., E-mail: rsmirnov@ucsd.edu; Krasheninnikov, S. I.; Pigarov, A. Yu. [University of California, San Diego, La Jolla, California 92093 (United States); Kukushkin, A. S. [NRC “Kurchatov Institute”, Moscow 123182 (Russian Federation); National Research Nuclear University MEPhI, Moscow 115409 (Russian Federation); Rognlien, T. D. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

    2016-01-15

    Two different oscillatory plasma regimes induced by seeding the plasma with high- and low-Z impurities are found for ITER-like divertor plasmas, using computer modeling with the DUSTT/UEDGE and SOLPS4.3 plasma-impurity transport codes. The oscillations are characterized by significant variations of the impurity-radiated power and of the peak heat load on the divertor targets. Qualitative analysis of the divertor plasma oscillations reveals different mechanisms driving the oscillations in the cases of high- and low-Z impurity seeding. The oscillations caused by the high-Z impurities are excited near the X-point by an impurity-related instability of the radiation-condensation type, accompanied by parallel impurity ion transport affected by the thermal and plasma friction forces. The driving mechanism of the oscillations induced by the low-Z impurities is related to the cross-field transport of the impurity atoms, causing alteration between the high and low plasma temperature regimes in the plasma recycling region near the divertor targets. The implications of the impurity-induced plasma oscillations for divertor operation in the next generation tokamaks are also discussed.

  2. Impurity-induced divertor plasma oscillations

    Science.gov (United States)

    Smirnov, R. D.; Kukushkin, A. S.; Krasheninnikov, S. I.; Pigarov, A. Yu.; Rognlien, T. D.

    2016-01-01

    Two different oscillatory plasma regimes induced by seeding the plasma with high- and low-Z impurities are found for ITER-like divertor plasmas, using computer modeling with the DUSTT/UEDGE and SOLPS4.3 plasma-impurity transport codes. The oscillations are characterized by significant variations of the impurity-radiated power and of the peak heat load on the divertor targets. Qualitative analysis of the divertor plasma oscillations reveals different mechanisms driving the oscillations in the cases of high- and low-Z impurity seeding. The oscillations caused by the high-Z impurities are excited near the X-point by an impurity-related instability of the radiation-condensation type, accompanied by parallel impurity ion transport affected by the thermal and plasma friction forces. The driving mechanism of the oscillations induced by the low-Z impurities is related to the cross-field transport of the impurity atoms, causing alteration between the high and low plasma temperature regimes in the plasma recycling region near the divertor targets. The implications of the impurity-induced plasma oscillations for divertor operation in the next generation tokamaks are also discussed.

  3. Radiative instabilities in plasmas: impurity motion and recombination effects

    Energy Technology Data Exchange (ETDEWEB)

    Morozov, D.K.; Herrera, J.J.E. [Instituto de Ciencias y Artes, Chiapas (Mexico). Escuela de Biologia

    1995-03-01

    Radiative instabilities in an impurity-seeded plasma are investigated when the plasma is supposed to be highly but partially ionized. Since in such plasmas radiative losses strongly depend on neutral and impurity densities, their dynamics are taken into account. As a result, a new radiative-recombination instability is found and described. We show that the influence of the ionization-recombination balance on plasma stability is sufficient for plasma densities above 10{sup 14} cm{sup -3}. The effects of a finite impurity Larmor radius are not small and play a stabilizing role as well as the thermal forces. On the other hand, compressibility of the magnetic field leads to plasma destabilization. We note that this radiative-recombination instability accumulates impurities in a cold zone while cleaning other regions. (Author).

  4. Impurity effects on trapped electron mode in tokamak plasmas

    Science.gov (United States)

    Du, Huarong; Wang, Zheng-Xiong; Dong, J. Q.

    2016-07-01

    The effects of impurity ions on the trapped electron mode (TEM) in tokamak plasmas are numerically investigated with the gyrokinetic integral eigenmode equation. It is shown that in the case of large electron temperature gradient ( η e ), the impurity ions have stabilizing effects on the TEM, regardless of peaking directions of their density profiles for all normalized electron density gradient R / L n e . Here, R is the major radius and L n e is the electron density gradient scale length. In the case of intermediate and/or small η e , the light impurity ions with conventional inwardly (outwardly) peaked density profiles have stabilizing effects on the TEM for large (small) R / L n e , while the light impurity ions with steep inwardly (outwardly) peaked density profiles can destabilize the TEM for small (large) R / L n e . Besides, the TEM driven by density gradient is stabilized (destabilized) by the light carbon or oxygen ions with inwardly (outwardly) peaked density profiles. In particular, for flat and/or moderate R / L n e , two independent unstable modes, corresponding respectively to the TEM and impurity mode, are found to coexist in plasmas with impurity ions of outwardly peaked density profiles. The high Z tungsten impurity ions play a stronger stabilizing role in the TEM than the low Z impurity ions (such as carbon and oxygen) do. In addition, the effects of magnetic shear and collision on the TEM instability are analyzed. It is shown that the collisionality considered in this work weakens the trapped electron response, leading to a more stable TEM instability, and that the stabilizing effects of the negative magnetic shear on the TEM are more significant when the impurity ions with outwardly peaked density profile are taken into account.

  5. Plasma Interactions with Mixed Materials and Impurity Transport

    Energy Technology Data Exchange (ETDEWEB)

    Rognlien, T. D. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Beiersdorfer, Peter [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Chernov, A. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Frolov, T. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Magee, E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Rudd, R. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Umansky, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-10-28

    The project brings together three discipline areas at LLNL to develop advanced capability to predict the impact of plasma/material interactions (PMI) on metallic surfaces in magnetic fusion energy (MFE) devices. These areas are (1) modeling transport of wall impurity ions through the edge plasma to the core plasma, (2) construction of a laser blow-off (LBO) system for injecting precise amounts of metallic atoms into a tokamak plasma, and (3) material science analysis of fundamental processes that modify metallic surfaces during plasma bombardment. The focus is on tungsten (W), which is being used for the ITER divertor and in designs of future MFE devices. In area (1), we have worked with the University of California, San Diego (UCSD) on applications of the UEDGE/DUSTT coupled codes to predict the influx of impurity ions from W dust through the edge plasma, including periodic edge-plasma oscillations, and revived a parallel version of UEDGE to speed up these simulations. In addition, the impurity transport model in the 2D UEDGE code has been implemented into the 3D BOUT++ turbulence/transport code to allow fundamental analysis of the impact of strong plasma turbulence on the impurity transport. In area (2), construction and testing of the LBO injection system has been completed. The original plan to install the LBO on the National Spherical Torus Experiment Upgrade (NSTX-U) at Princeton and its use to validate the impurity transport simulations is delayed owing to NSTX-U being offline for substantial magnetic coil repair period. In area (3), an analytic model has been developed to explain the growth of W tendrils (or fuzz) observed for helium-containing plasmas. Molecular dynamics calculations of W sputtering by W and deuterium (D) ions shows that a spatial blending of interatomic potentials is needed to describe the near-surface and deeper regions of the material.

  6. Runaway electron dynamics in tokamak plasmas with high impurity content

    Science.gov (United States)

    Martín-Solís, J. R.; Loarte, A.; Lehnen, M.

    2015-09-01

    The dynamics of high energy runaway electrons is analyzed for plasmas with high impurity content. It is shown that modified collision terms are required in order to account for the collisions of the relativistic runaway electrons with partially stripped impurity ions, including the effect of the collisions with free and bound electrons, as well as the scattering by the full nuclear and the electron-shielded ion charge. The effect of the impurities on the avalanche runaway growth rate is discussed. The results are applied, for illustration, to the interpretation of the runaway electron behavior during disruptions, where large amounts of impurities are expected, particularly during disruption mitigation by massive gas injection. The consequences for the electron synchrotron radiation losses and the resulting runaway electron dynamics are also analyzed.

  7. Effect of impurities on kinetic transport processes in fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Braun, Stefanie

    2010-12-10

    Within the framework of this thesis, different problems arising in connection with impurities have been investigated. Collisional damping of zonal flows in tokamaks: Since the Coulomb collision frequency increases with increasing ion charge, heavy, highly charged impurities play an important role in this process. The effect of such impurities on the linear response of the plasma to an external potential perturbation, as caused by zonal flows, is calculated with analytical methods. In comparison with a pure plasma, the damping of the flows occurs, as expected, considerably faster; for experimentally relevant parameters, the enhancement exceeds the effective charge Z{sub eff} of the plasma. Impurity transport driven by microturbulence in tokamaks: With regard to impurities, it is especially important whether the resulting flows are directed inwards or outwards, since they are deleterious for core energy confinement on the one hand, but on the other hand help protecting plasma-facing components from too high energy fluxes in the edge region. A semi-analytical model is presented describing the resulting impurity fluxes and the stability boundary of the underlying mode. The main goal is to bridge the gap between, on the one hand, costly numerical simulations, which are applicable to a broad range of problems but yield scarcely traceable results, and, on the other hand, analytical theory, which might ease the interpretation of the results but is so far rather rudimentary. The model is based on analytical formulae whenever possible but resorts to a numerical treatment when the approximations necessary for an analytical solution would lead to a substantial distortion of the results. Both the direction of the impurity flux and the stability boundary are found to depend sensitively on the plasma parameters such as the impurity density and the temperature gradient. Pfirsch-Schlueter transport in stellarators: Due to geometry effects, collisional transport plays a much more

  8. Radiated power distributions in impurity-seeded plasmas in LHD

    Energy Technology Data Exchange (ETDEWEB)

    Morisaki, T., E-mail: morisaki@nifs.ac.jp [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Nagoya University, Nagoya 464-8602 (Japan); Oyama, K. [Nagoya University, Nagoya 464-8602 (Japan); Tamura, N.; Masuzaki, S.; Akiyama, T.; Motojima, G.; Miyazawa, J.; Peterson, B.J. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan); Ohno, N. [Nagoya University, Nagoya 464-8602 (Japan); Yamada, H. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki 509-5292 (Japan)

    2015-08-15

    In LHD, impurity seeding has been performed to enhance the radiative cooling in the edge region. Neon, nitrogen and argon were seeded by gas puffing, and the behaviour of those impurities in the plasma was investigated with the innovative diagnostic method. Two bolometer arrays were used to measure the two-dimensional radiated power distribution. Using the tomographic technique, radiated power distributions on a poloidal plane can be obtained with the high time resolution. During the discharge with neon puff, considerable radiation from the core region was observed, in addition to the strong edge radiation. In spite of the highly radiated power, plasma did not result in the radiation collapse. On the other hand, in the nitrogen-seeded discharge, the strong radiation only from the peripheral region was observed. Different time evolutions of the total radiated power between neon and nitrogen seeded discharges were observed after stopping each impurity puff.

  9. Identification and Manipulations of Impurity Ions in Magnesium Ion Plasma

    Science.gov (United States)

    Anderegg, F.; Affolter, M.; Driscoll, C. F.; Dubin, D. H. E.

    2011-10-01

    A nominally ``pure'' Mg24+ ion plasma accumulates impurity ions over periods of hours to days by charge exchange with residual background gas (P ~10-10 Torr) in a Penning-Malmberg trap. We use thermal cyclotron spectroscopy (TCS) to identify ion impurities, and observe spatial separation at low temperatures. TCS consists of applying rf bursts at the impurity cyclotron frequencies, with LIF measurement of the majority species heating due to collisions with the heated impurites. We find that for short bursts the heating is proportional to the burst amplitude squared, and to the square of the burst duration, as predicted by a simple single particle model. We spatially separate the impurities from the Magnesium ions by two different techniques: a) With laser cooling to T ions at larger radii. We typically observe a 5-20% ``hole'' in the center of the Mg plasma where the ``dark'' lower-mass impurities reside; and we directly observe the Mg25 and Mg26 at the outer edge of the Mg24 column. b) Resonant laser pressure in the z-direction pushes on the Mg24, and the species separates longitudinally when this laser force is greater than the mass-dependent centrifugal force. Supported by NSF PHY-0903877 and DOE DE-SC0002451.

  10. Quasilinear Carbon Transport In An Impurity Hole Plasma In LHD

    Energy Technology Data Exchange (ETDEWEB)

    Mikkelsen, David R. [PPPL; Tanaka, K. [NIFS; Nunami, M. [NIFS; Watanabe, T-H. [Nagoya University; Sugama, H. [NIFS; Yoshinuma, M. [NIFS; Suzuki, Y. [NIFS; Goto, M. [NIFS; Morita, S. [NIFS; Wieland, B. [NIFS; Yamada, I. [NIFS; Yashura, R. [NIFS; Akiyama, T. [NIFS; Pablant, Novimir A. [PPPL

    2014-04-01

    Comprehensive electrostatic gyrokinetic linear stability calculations for ion-scale microinstabilities in an LHD plasma with an ion-ITB and carbon "impurity hole" are used to make quasilinear estimates of particle flux to explore whether microturbulence can explain the observed outward carbon fluxes that flow "up" the impurity density gradient. The ion temperature is not stationary in the ion-ITB phase of the simulated discharge, during which the core carbon density decreases continuously. To fully sample these varying conditions the calculations are carried out at three radial locations and four times. The plasma parameter inputs are based on experimentally measured profiles of electron and ion temperature, as well as electron and carbon density. The spectroscopic line-average ratio of hydrogen and helium densities is used to set the density of these species. Three ion species (H,He,C) and the electrons are treated kinetically, including collisions. Electron instability drive does enhance the growth rate significantly, but the most unstable modes have characteristics of ion temperature gradient (ITG) modes in all cases. As the carbon density gradient is scanned between the measured value and zero, the quasilinear carbon flux is invariably inward when the carbon density profile is hollow, so turbulent transport due to the instabilities considered here does not explain the observed outward flux of impurities in impurity hole plasmas. The stiffness of the quasilinear ion heat flux is found to be 1.7-2.3, which is lower than several estimates in tokamaks.

  11. Approaches to modeling of plasmas containing impurity at arbitrary concentration

    Science.gov (United States)

    Tokar, Mikhail Z.

    2016-02-01

    A new approximate method to modeling of two-ion-species plasmas with arbitrary concentration of impurity is developed. It based on the usage of equations for the electron density and the ratio of the ion species densities as new dependent variables. In contrast to motion equations for the ion mass velocities used normally, those for the new variables have a singularity at the Debye sheath only, as in the case of a one species plasma. Computations for the most critical situations of weak and intermediate friction between species due to Coulomb collisions reproduce nearly perfectly the results got by solving the original equations, however within a calculation time reduced by a factor of 102-103. In the case of strong friction, where ions’ velocities are very close each other, the normal procedure does not converge at all, but the new one, being precise in this limit, operates very reliably. Calculations are done for conditions typical in the linear device PSI-2, with deuterium plasmas seeded by neon impurity. For fixed electron and ion temperatures a critical density of impurity atoms is found, at which the electron density grows without limits. Such a catastrophic behavior does not occur if the electron and ion heat balances are taken into account to calculate the temperature profiles self-consistently.

  12. The effect of working gas impurities on plasma jets

    Energy Technology Data Exchange (ETDEWEB)

    Liu, X. Y.; He, M. B., E-mail: pulhmb@mail.hust.edu.cn [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, WuHan, HuBei 430074 (China); IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China); Liu, D. W. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, Huazhong University of Science and Technology, WuHan, HuBei 430074 (China); IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai 200240 (China); State Key Laboratory of Electrical Insulation and Power Equipment, Xi' an Jiaotong University, Xi' an, Shanxi 710049 (China)

    2015-04-15

    Air intrusion reduced the purity of working gas inside the tube for plasma jet, and thereby, affected the discharge dynamics. In this paper, the effect of using working gas with different purity level (helium purity 99.99999%, 99.99%, 99.9%, and 99%) on photoionization and the chemical reactivity of plasma jet were studied using a 2 dimensional plasma jet model. Photoionization of air species acted as a source of pre-ionization in front of the ionization region, which facilitated the transition from localized discharge to streamers inside the tube. The density of reactive species inside the tube was found to increase with the concentration of working gas impurities. For the highest purity helium (99.99999%), despite a low photoionization rate and the distance between the photoionization region and ionization region inside the tube, by increasing the applied voltage and decreasing the distance between the electrode and nozzle, plasma jets were formed.

  13. Anomalous diffusion, clustering, and pinch of impurities in plasma edge turbulence

    DEFF Research Database (Denmark)

    Priego, M.; Garcia, O.E.; Naulin, V.

    2005-01-01

    The turbulent transport of impurity particles in plasma edge turbulence is investigated. The impurities are modeled as a passive fluid advected by the electric and polarization drifts, while the ambient plasma turbulence is modeled using the two-dimensional Hasegawa-Wakatani paradigm for resistive......-diffusion analysis of the evolution of impurity puffs. Additional effects appear for inertial impurities as a consequence of compressibility. First, the density of inertial impurities is found to correlate with the vorticity of the electric drift velocity, that is, impurities cluster in vortices of a precise...

  14. Influence of impurity seeding on plasma burning scenarios for ITER

    Energy Technology Data Exchange (ETDEWEB)

    Ivanova-Stanik, I., E-mail: irena.ivanova-stanik@ifpilm.pl [Institute of Plasma Physics and Laser Microfusion, Hery 23, 01-497 Warsaw (Poland); Zagórski, R. [Institute of Plasma Physics and Laser Microfusion, Hery 23, 01-497 Warsaw (Poland); Voitsekhovitch, I. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Brezinsek, S. [Forschungszentrum Jülich GmbH Institut für Energie-und Klimaforschung—Plasmaphysik, Jülich 52425 (Germany)

    2016-11-01

    Highlights: • The self-consistent (core-edge) COREDIV code has been used to analyze ITER standard inductive scenarios with neon and argon seeding. • In order to achieve wide operational window with the power crossing separatrix above the H-L threshold and simultaneously with tolerable heat load to target plates (<40 MW) relatively strong impurity transport in the core and SOL regions is necessary. • For argon seeding, the operational window is much smaller than for neon case due to enhanced core radiation (in comparison to Ne). - Abstract: ITER expects to produce fusion power of about 0.5GW when operating with tungsten (W) divertor and beryllium (Be) wall. The influx of W from divertor can have significant influence on the discharge performance. This work describes predictive integrated numerical modeling of ITER discharges using the COREDIV code, which self-consistently solves the 1D radial energy and particle transport in the core region and 2D multi-fluid transport in the SOL. Calculations are performed for inductive ITER scenarios with intrinsic (W, Be and He) impurities and with seeded impurities (Ne and Ar) for different particle and heat transport in the core and different radial transport in the SOL. Simulations show, that only for sufficiently high radial diffusion (both in the core and in the SOL regions), it is possible to achieve H-mode mode plasma operation (power to SOL > L-H threshold power) with acceptable low level of power reaching the divertor plates. For argon seeding, the operational window is much smaller than for neon case due to enhanced core radiation (in comparison to Ne). Particle transport in the core characterized by the ratio of particle diffusion to thermal conductivity) has strong influence on the predicted ITER performance.

  15. Modelling of turbulent impurity transport in fusion edge plasmas using measured and calculated ionization cross sections

    CERN Document Server

    Kendl, Alexander

    2014-01-01

    Turbulent transport of trace impurities impurities in the edge and scrape-off-layer of tokamak fusion plasmas is modelled by three dimensional electromagnetic gyrofluid computations including evolution of plasma profile gradients. The source function of impurity ions is dynamically computed from pre-determined measured and calculated electron impact ionization cross section data. The simulations describe the generation and further passive turbulent E-cross-B advection of the impurities by intermittent fluctuations and coherent filamentary structures (blobs) across the scrape-off-layer.

  16. Modelling of plasma behaviour in the vicinity of intensive impurity sources

    Science.gov (United States)

    Tokar, Mikhail Z.; Ding, Rui; Koltunov, Mikhail

    2010-07-01

    Plasma behaviour in the vicinity of strong sources of impurities is considered by taking into account quasi-neutrality, Coulomb collisions of background particles with impurity ions, radiation losses and sinks of charged particles to bounding material surfaces. If several ion species are present in the plasma the generalized Bohm criterion requires that a certain function of the main ion velocity changes its sign when moving along the magnetic field from the distant plasma through the impurity source to the surface. This allows us to formulate the 'regularity' conditions for the motion equation of the main ions and a numerical approach to find the only physical solution without singularities is elaborated. Calculations of plasma parameters in the shadow of a limiter, through which impurities are injected, have been done for the conditions of impurity seeding experiments in the tokamak TEXTOR.

  17. Influence of radiative processes on the ignition of deuterium–tritium plasma containing inactive impurities

    Energy Technology Data Exchange (ETDEWEB)

    Gus’kov, S. Yu., E-mail: guskov@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Sherman, V. E. [Peter the Great St. Petersburg Polytechnic University (Russian Federation)

    2016-08-15

    The degree of influence of radiative processes on the ignition of deuterium–tritium (DT) plasma has been theoretically studied as dependent on the content of inactive impurities in plasma. The analytic criterion of plasma ignition in inertial confinement fusion (ICF) targets is modified taking into account the absorption of intrinsic radiation from plasma in the ignition region. The influence of radiative processes on the DT plasma ignition has been analytically and numerically studied for plasma that contains a significant fraction of inactive impurities either as a result of DT fuel mixing with ICF target ablator material or as a result of using light metal DT-hydrides as solid noncryogenic fuel. It has been shown that the effect of the absorption of intrinsic radiation leads to lower impurity-induced increase in the ignition energy as compared to that calculated in the approximation of optically transparent ignition region.

  18. Influence of radiative processes on the ignition of deuterium-tritium plasma containing inactive impurities

    Science.gov (United States)

    Gus'kov, S. Yu.; Sherman, V. E.

    2016-08-01

    The degree of influence of radiative processes on the ignition of deuterium-tritium (DT) plasma has been theoretically studied as dependent on the content of inactive impurities in plasma. The analytic criterion of plasma ignition in inertial confinement fusion (ICF) targets is modified taking into account the absorption of intrinsic radiation from plasma in the ignition region. The influence of radiative processes on the DT plasma ignition has been analytically and numerically studied for plasma that contains a significant fraction of inactive impurities either as a result of DT fuel mixing with ICF target ablator material or as a result of using light metal DT-hydrides as solid noncryogenic fuel. It has been shown that the effect of the absorption of intrinsic radiation leads to lower impurity-induced increase in the ignition energy as compared to that calculated in the approximation of optically transparent ignition region.

  19. Extended numerical modeling of impurity neoclassical transport in tokamak edge plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, H.; Yamoto, S.; Hatayama, A. [Graduate School of Science and Technology, Keio University, Hiyoshi, Yokohama (Japan); Homma, Y. [Graduate School of Science and Technology, Keio University, Hiyoshi, Yokohama (Japan); Research Fellow of Japan Society for the Promotion of Science, Tokyo (Japan)

    2016-08-15

    Understanding of impurity transport in tokamaks is an important issue in order to reduce the impurity contamination in fusion core plasmas. Recently, a new kinetic numerical scheme of impurity classical/neoclassical transport has been developed. This numerical scheme makes it possible to include classical self-diffusion (CL SD), classical inward pinch (CL IWP), and classical temperature screening effect (CL TSE) of impurity ions. However, impurity neoclassical transport has been modeled only in the case where background plasmas are in the Pfirsch-Schluter (PS) regime. The purpose of this study is to extend our previous model to wider range of collisionality regimes, i.e., not only the PS regime, but also the plateau regime. As in the previous study, a kinetic model with Binary Collision Monte-Carlo Model (BMC) has been adopted. We focus on the modeling of the neoclassical self-diffusion (NC SD) and the neoclassical inward pinch (NC IWP). In order to simulate the neoclassical transport with the BCM, velocity distribution of background plasma ions has been modeled as a deformed Maxwell distribution which includes plasma density gradient. Some test simulations have been done. As for NC SD of impurity ions, our scheme reproduces the dependence on the collisionality parameter in wide range of collisionality regime. As for NC IWP, in cases where test impurity ions and background ions are in the PS and plateau regimes, parameter dependences have been reproduced. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Impurities in a non-axisymmetric plasma: transport and effect on bootstrap current

    CERN Document Server

    Mollén, Albert; Smith, Håkan M; Braun, Stefanie; Helander, Per

    2015-01-01

    Impurities cause radiation losses and plasma dilution, and in stellarator plasmas the neoclassical ambipolar radial electric field is often unfavorable for avoiding strong impurity peaking. In this work we use a new continuum drift-kinetic solver, the SFINCS code (the Stellarator Fokker-Planck Iterative Neoclassical Conservative Solver) [M. Landreman et al., Phys. Plasmas 21 (2014) 042503] which employs the full linearized Fokker-Planck operator, to calculate neoclassical impurity transport coefficients for a Wendelstein 7-X (W7-X) magnetic configuration. We compare SFINCS calculations with theoretical asymptotes in the high collisionality limit. In intermediate and high collisionality regimes, a momentum conserving collision operator is critical to correctly determine the impurity transport coefficients, and a simple pitch-angle scattering approximation can lead to transport predictions in the wrong direction. In the low collisionality regime pitch-angle scattering is sufficient to accurately describe impuri...

  1. Turbulent transport of impurities in a magnetized plasma; Transport turbulent d'impuretes dans un plasma magnetise

    Energy Technology Data Exchange (ETDEWEB)

    Dubuit, N

    2006-10-15

    This work deals with the transport of impurities in magnetically confined thermonuclear plasmas. The accumulation of impurities in the core of the plasma would imply dramatic losses of energy that may lead to the extinction of the plasma. On the opposite, the injection of impurities in the plasma edge is considered as an efficient means to extract heat without damaging the first wall. The balance between these 2 contradictory constraints requires an accurate knowledge of the impurity transport inside the plasma. The effect of turbulence, the main transport mechanism for impurities is therefore a major issue. In this work, the complete formula of a turbulent flow of impurities for a given fluctuation spectrum has been inferred. The origin and features of the main accumulation processes have been identified. The main effect comes from the compressibility of the electrical shift speed in a plane perpendicular to the magnetic field. This compressibility appears to be linked to the curvature of the magnetic field. A less important effect is a thermal-diffusion process that is inversely proportional to the number of charges and then disappears for most type of impurities except the lightest. This effect implies an impurity flux proportional to the temperature gradient and its direction can change according to the average speed of fluctuations. A new version of the turbulence code TRB has been developed. This new version allows the constraints of the turbulence not by the gradients but by the flux which is more realistic. The importance of the processes described above has been confirmed by a comparison between calculation and experimental data from Tore-supra and the Jet tokamak. The prevailing role of the curvature of the magnetic field in the transport impurity is highlighted. (A.C.)

  2. Moderation of neoclassical impurity accumulation in high temperature plasmas of helical devices

    CERN Document Server

    Velasco, J L; Satake, S; Alonso, A; Nunami, M; Yokoyama, M; Sato, M; Dinklage, A; Estrada, T; Fontdecaba, J M; Liniers, M; McCarthy, K J; Medina, F; Van Milligen, B Ph; Ochando, M; Parra, F; Sugama, H; Zhezhera, A

    2016-01-01

    Achieving impurity and helium ash control is a crucial issue in the path towards fusion-grade magnetic confinement devices, and this is particularly the case of helical reactors, whose low-collisionality ion-root operation scenarios usually display a negative radial electric field which is expected to cause inwards impurity pinch. In these work we discuss, based on experimental measurements and standard predictions of neoclassical theory, how plasmas of very low ion collisionality, similar to those observed in the impurity hole of the Large Helical Device, can be an exception to this general rule, and how a negative radial electric field can coexist with an outward impurity flux. This interpretation is supported by comparison with documented discharges available in the International Stellarator-Heliotron Profile Database, and it can be extrapolated to show that achievement of high ion temperature in the core of helical devices is not fundamentally incompatible with low core impurity content.

  3. Impurity intrusion in radio-frequency micro-plasma jets operated in ambient air

    CERN Document Server

    Niermann, B; Böke, M; Winter, J

    2011-01-01

    Space and time resolved concentrations of helium metastable atoms in an atmospheric pressure radio-frequency micro-plasma jet were measured using tunable diode laser absorption spectroscopy. Spatial profiles as well as lifetime measurements show significant influences of air entering the discharge from the front nozzle and of impurities originating from the gas supply system. Quenching of metastables was used to deduce quantitative concentrations of intruding impurities. The impurity profile along the jet axis was determined from optical emission spectroscopy as well as their dependance on the feed gas flow through the jet.

  4. Impurity-induced local modes in one-dimensional dusty plasma chains

    Institute of Scientific and Technical Information of China (English)

    Ren Yong-Chao; Wang Xin-Shang; Wang Xiao-Gang

    2012-01-01

    The effects of impurity on eigenmodes in one-dimensional dusty plasma lattices are studied.It is found that local modes can be excited besides lattice waves,due to the existence of an impurity particle.The dispersion relations of the modes are derived accordingly.Properties of the lattice and local modes are also analyzed and discussed,particularly for their symmetric features and conditions of the mode excitation.

  5. Impurity screening and edge-plasma modifications for plasma devices with liquid walls.

    Science.gov (United States)

    Rognlien, Thomas D.

    2001-10-01

    The edge-plasma region of magnetic fusion confinement devices plays various important roles, two of which are (1), shielding the core plasma from gas and impurities, and (2), influencing the core-boundary plasma temperature and density. The first role is crucial to the successful use of liquid walls, and the second role, if controllable, could enhance core energy confinement by reducing drives for core turbulence. In fusion reactors, liquid walls would allow higher wall power-loading, and sufficiently thick walls would greatly reduce neutron activation of support structures.(R.W. Moir, Nucl. Fusion 37), 557 (1997); M. Abdou, et al., Fusion Eng. Design 54, 181 (2001). In addition, liquid divertors could largely eliminate the surface erosion problem.(J.N. Brooks, et al.), J. Nucl. Mater. 290-293, 185 (2001.); R.F. Mattas, et al., Fusion Eng. Design 49-50, 127 (2000). In this talk, results of self-consistent, 2-D edge transport simulations are presented to quantify the allowable influx of liquid-wall vapor for various candidate liquids (Li, Flibe, SnLi, Sn) which, in turn, set the allowable surface operating temperatures that controls the vapor evaporation rates. The results are explained and summarized by a reduced model that includes the radiation characteristics of different impurity species, and the competition between anomalous radial transport and parallel flow along the B-field. The modification of the edge plasma properties by liquid walls is also presented, with an emphasis on the low-recycling regime thought possible by the use of lithium, which naturally leads to a high edge-temperature regime. The effect of long mean-free-path parallel transport in the high-temperature regime is described by the bounce-averaged, particle- and energy-loss model.

  6. Impurity effects on residual zonal flow in deuterium (D)-tritium (T) plasmas

    Science.gov (United States)

    Guo, Weixin; Wang, Lu; Zhuang, Ge

    2017-05-01

    Significant effects of impurities on residual zonal flow (ZF) in deuterium (D)-tritium (T) plasmas are found. When the gyroradius of impurities is larger (smaller) than that of main ions, the intermediate scale (radial wavelength between trapped ion radial width {ρ\\text{bi}} and trapped electron radial width {ρ\\text{be}} ) residual ZF level is increased (decreased) due to the presence of various impurities with the tolerance concentration in JET and ITER, even for trace tungsten (W). For short scale (radial wavelength comparable to {ρ\\text{be}} ) region, the residual ZF level is increased by most of the impurities. Moreover, the trend of stronger intermediate residual ZF in D-T plasmas with heavier effective isotope mass is weakened by non-trace impurities, but is not influenced by trace W. These results reveal that the presence of impurities can modify residual ZF, and possibly further affect the ZF regulation of turbulence as well as the associated anomalous transport and confinement in magnetic fusion plasmas. The potential relevance of our findings to experimental observations and simulation results is discussed.

  7. Impurities in a non-axisymmetric plasma: Transport and effect on bootstrap current

    Energy Technology Data Exchange (ETDEWEB)

    Mollén, A., E-mail: albertm@chalmers.se [Department of Applied Physics, Chalmers University of Technology, Göteborg (Sweden); Max-Planck-Institut für Plasmaphysik, 17491 Greifswald (Germany); Landreman, M. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Smith, H. M.; Helander, P. [Max-Planck-Institut für Plasmaphysik, 17491 Greifswald (Germany); Braun, S. [Max-Planck-Institut für Plasmaphysik, 17491 Greifswald (Germany); German Aerospace Center, Institute of Engineering Thermodynamics, Pfaffenwaldring 38-40, D-70569 Stuttgart (Germany)

    2015-11-15

    Impurities cause radiation losses and plasma dilution, and in stellarator plasmas the neoclassical ambipolar radial electric field is often unfavorable for avoiding strong impurity peaking. In this work we use a new continuum drift-kinetic solver, the SFINCS code (the Stellarator Fokker-Planck Iterative Neoclassical Conservative Solver) [M. Landreman et al., Phys. Plasmas 21, 042503 (2014)] which employs the full linearized Fokker-Planck-Landau operator, to calculate neoclassical impurity transport coefficients for a Wendelstein 7-X (W7-X) magnetic configuration. We compare SFINCS calculations with theoretical asymptotes in the high collisionality limit. We observe and explain a 1/ν-scaling of the inter-species radial transport coefficient at low collisionality, arising due to the field term in the inter-species collision operator, and which is not found with simplified collision models even when momentum correction is applied. However, this type of scaling disappears if a radial electric field is present. We also use SFINCS to analyze how the impurity content affects the neoclassical impurity dynamics and the bootstrap current. We show that a change in plasma effective charge Z{sub eff} of order unity can affect the bootstrap current enough to cause a deviation in the divertor strike point locations.

  8. Simulation of runaway electron generation during plasma shutdown by impurity injection

    Energy Technology Data Exchange (ETDEWEB)

    Feher, Tamas

    2011-03-15

    Disruptions are dangerous instabilities in tokamaks that should be avoided or mitigated. One possible disruption mitigation method is to inject impurities into the plasma to shut it down in a controlled way. Runaway Electrons (REs) can be generated after the plasma is cooled down by the impurities and these electrons can damage the tokamak. In this work a simulation code is developed to investigate different disruption mitigation scenarios. The response of the bulk plasma, more precisely the temperature evolution of electrons, deuterium and impurity ions are described by energy balance equations in a 1D cylindrical plasma model. The induction and resistive diffusion of electric field is calculated. RE generation rates are used to calculate the runaway current. The Dreicer, hot-tail and avalanche effect is taken into account and a simple model for RE losses is also included. RE generation is studied in JET-like plasmas during pellet injection. Carbon pellets cause effective cooling but these scenarios are prone to runaway generation. A mixture of argon and deuterium gas could be used for safe shutdown without RE generation. In ITER the hot-tail RE generation process becomes important, and the simulation is therefore extended to take this into account. Shutdown scenarios with different concentration of neon and argon impurities were tested in ITER-like plasmas. To simplify the problem the impurity injection into the plasma is not modeled in these cases, only the response of the bulk plasma. The avalanche process cannot be suppressed in a simple way and would produce high runaway current. It can be avoided if some runaway loss phenomenon is included in the simulations, like diffusion due to magnetic perturbations

  9. Study on impurity radiation and transport of JT-60U plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Ishijima, Tatsuo [Tsukuba Univ., Ibaraki (Japan)

    2000-03-01

    This thesis describes an investigation on impurity transport in the JT-60U tokamak plasma both in the core and the divertor plasmas to provide a better understanding of plasma physics. This work has been performed under the collaborative graduate school between University of Tsukuba and Naka Fusion Research Establishment of Japan Atomic Energy Research Institute. A radiative divertor experiment with neon gas puff was carried out with an aim of investigating impurity behaviors in the divertor, after the open divertor was modified to the pumped W-shaped divertor. To evaluate neon radiation, analysis was made for lines from neon ions measured with a VUV spectrometer in the divertor plasma. As a result, lines from Ne IV-Ne VIII were identified. By combining the measurement with an absolutely calibrated multi-channel interference filter spectrometer and that with the VUV spectrometer, the radiation loss through neon line emission was estimated in the divertor plasma. In the case of pumping off, the detached plasma evolved into a MARFE. It was observed that the line intensities of highly ionized neon (Ne VII, Ne VIII) increased simultaneously with the formation of the MARFE and furthermore increased after the MARFE formation. It is considered that after the divertor plasma was detached, the plasma flow velocity and the friction force were weaker in the case of pumping off than in the case of pumping on and more impurities moved toward the X-point region. This observation implies reduction of impurity back flow from the divertor to the upstream by the friction force. This thesis indicates that the plasma flow in the SOL (Scrape-Off Layer) is important to confine the impurity in the divertor region and prevent the MARFE for the first time. In reversed shear discharges with ITB (internal transport barrier), electron density, temperature and radiation power strongly increased inside the ITB. The core radiation was analyzed by bolometry, VUV spectrometer and CXRS (charge

  10. Metal impurity fluxes and plasma-surface interactions in EXTRAP T2R

    Science.gov (United States)

    Bergsåker, H.; Menmuir, S.; Rachlew, E.; Brunsell, P. R.; Frassinetti, L.; Drake, J. R.

    2008-03-01

    The EXTRAP T2R is a large aspect ratio Reversed Field Pinch device. The main focus of interest for the experiments is the active feedback control of resistive wall modes [1]. With feedback it has been possible to prolong plasma discharges in T2R from about 20 ms to nearly 100 ms. In a series of experiments in T2R, in H- and D- plasmas with and without feedback, quantitative spectroscopy and passive collector probes have been used to study the flux of metal impurities. Time resolved spectroscopic measurements of Cr and Mo lines showed large metal release towards discharge termination without feedback. Discharge integrated fluxes of Cr, Fe, Ni and Mo were also measured with collector probes at wall position. Reasonable quantitative agreement was found between the spectroscopic and collector probe measurements. The roles of sputtering, thermal evaporation and arcing in impurity production are evaluated based on the composition of the measured impurity flux.

  11. VUV/XUV measurements of impurity emission in plasmas with liquid lithium surfaces on LTX

    Science.gov (United States)

    Tritz, Kevin; Bell, Ronald E.; Beiersdorfer, Peter; Boyle, Dennis; Clementson, Joel; Finkenthal, Michael; Kaita, Robert; Kozub, Tom; Kubota, Shigeyuki; Lucia, Matthew; Majeski, Richard; Merino, Enrique; Schmitt, John; Stutman, Dan

    2014-12-01

    The VUV/XUV spectrum has been measured on the Lithium Tokamak eXperiment (LTX) using a transmission grating imaging spectrometer (TGIS) coupled to a direct-detection x-ray charge-coupled device camera. TGIS data show significant changes in the ratios between the lithium and oxygen impurity line emission during discharges with varying lithium wall conditions. Lithium coatings that have been passivated by lengthy exposure to significant levels of impurities contribute to a large O/Li ratio measured during LTX plasma discharges. Furthermore, previous results have indicated that a passivated lithium film on the plasma facing components will function as a stronger impurity source when in the form of a hot liquid layer compared to a solid lithium layer. However, recent TGIS measurements of plasma discharges in LTX with hot stainless steel boundary shells and a fresh liquid lithium coating show lower O/Li impurity line ratios when compared to discharges with a solid lithium film on cool shells. These new measurements help elucidate the somewhat contradictory results of the effects of solid and liquid lithium on plasma confinement observed in previous experiments.

  12. Impurity induced neutralization of MeV energy protons in JET plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Gondhalekar, A. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Korotkov, A.A. [AF Ioffe Institute, Saint Petersburg (Russian Federation)

    1994-07-01

    A model elucidating the role of carbon and beryllium, the main impurities in JET plasmas, in neutralizing MeV energy protons, which arise during ICRF heating of deuterium plasmas in the hydrogen minority heating mode D(H), and from D-D fusion reactions, is presented. The model establishes charge transfer from hydrogen-like impurity ions to protons as the main process for neutralization. Calculations for deducing the proton energy distribution function from measured hydrogen flux are described. The validity of the model is tested by using it to described the measured flux in different conditions of plasma heating and fueling. Further, it is used to deduce the background thermal deuterium atom density at the plasma center. 9 refs., 6 figs.

  13. Moderation of neoclassical impurity accumulation in high temperature plasmas of helical devices

    Science.gov (United States)

    Velasco, J. L.; Calvo, I.; Satake, S.; Alonso, A.; Nunami, M.; Yokoyama, M.; Sato, M.; Estrada, T.; Fontdecaba, J. M.; Liniers, M.; McCarthy, K. J.; Medina, F.; Van Milligen, B. Ph; Ochando, M.; Parra, F.; Sugama, H.; Zhezhera, A.; The LHD Experimental Team; The TJ-II Team

    2017-01-01

    Achieving impurity and helium ash control is a crucial issue in the path towards fusion-grade magnetic confinement devices, and this is particularly the case of helical reactors, whose low-collisionality ion-root operation scenarios usually display a negative radial electric field which is expected to cause inwards impurity pinch. In this work we discuss, based on experimental measurements and standard predictions of neoclassical theory, how plasmas of very low ion collisionality, similar to those observed in the impurity hole of the large helical device (Yoshinuma et al and The LHD Experimental Group 2009 Nucl. Fusion 49 062002, Ida et al and The LHD Experimental Group 2009 Phys. Plasmas 16 056111 and Yokoyama et al and LHD Experimental Group 2002 Nucl. Fusion 42 143), can be an exception to this general rule, and how a negative radial electric field can coexist with an outward impurity flux. This interpretation is supported by comparison with documented discharges available in the International Stellarator-Heliotron Profile Database, and it can be extrapolated to show that achievement of high ion temperature in the core of helical devices is not fundamentally incompatible with low core impurity content.

  14. Impurity generation, transport and redeposition at plasma boundary

    Energy Technology Data Exchange (ETDEWEB)

    Kojima, M.; Ido, Y.; Ezumi, N.; Ohno, N.; Takamura, S. [Nagoya Univ. (Japan)

    1997-12-31

    Erosion and redeposition processes have been investigated using a linear plasma device and a Monte-Carlo simulation code. Molybdenum substrate is exposed to argon plasmas for oblique incidence of magnetic field under well-defined plasma conditions. The effect of magnetic field directions on the erosion distribution is clearly observed. We have a qualitative explanation for the erosion profiles with the effect of prompt redeposition of high Z material in comparison with numerical code predictions. However, we have quantitative differences for their erosion rates. (author)

  15. Vacuum ultraviolet spectroscopy in detached plasmas with impurity gas seeding in LHD

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, C., E-mail: csuzuki@nifs.ac.jp; Murakami, I.; Akiyama, T.; Masuzaki, S.; Funaba, H.; Yoshinuma, M.

    2015-08-15

    We have carried out vacuum ultraviolet (VUV) spectroscopy of impurity ions in detached plasmas with impurity gas seeding in the Large Helical Device (LHD). In neon (Ne) gas seeding experiments, temporal evolutions of VUV spectral lines from Ne IV–VIII were recorded by a grazing incidence spectrometer. In addition, spatial profiles of fully ionized Ne density were measured by charge exchange spectroscopy. An electron temperature range where each ion emits is inferred based on the comparisons of the measured line intensity ratios with the calculations using collisional-radiative models.

  16. Wave Propagation and Diffusive Transition of Oscillations in Pair Plasmas with Dust Impurities

    CERN Document Server

    Atamaniuk, Barbara

    2008-01-01

    In view of applications to electron-positron pair-plasmas and fullerene pair-ion-plasmas containing charged dust impurities a thorough discussion is given of three-component Plasmas. Space-time responses of multi-component linearized Vlasov plasmas on the basis of multiple integral equations are invoked. An initial-value problem for Vlasov-Poisson -Ampere equations is reduced to the one multiple integral equation and the solution is expressed in terms of forcing function and its space-time convolution with the resolvent kernel. The forcing function is responsible for the initial disturbance and the resolvent is responsible for the equilibrium velocity distributions of plasma species. By use of resolvent equations, time-reversibility, space-reflexivity and the other symmetries are revealed. The symmetries carry on physical properties of Vlasov pair plasmas, e.g., conservation laws. Properly choosing equilibrium distributions for dusty pair plasmas, we can reduce the resolvent equation to: (i) the undamped disp...

  17. Control of core argon impurity profile by ECH in KSTAR L-mode plasmas

    Science.gov (United States)

    Hong, Joohwan; Lee, Seung Hun; Kim, Juhyung; Seon, C. R.; Lee, S. G.; Park, G. Y.; Lee, K. D.; Henderson, S. S.; Lee, H. Y.; Park, Jae Sun; Jang, Juhyeok; Jang, Siwon; Jeon, Taemin; O'Mullane, M.; Choe, Wonho

    2015-06-01

    Experiments on trace argon impurity transport in L-mode discharges were performed on Korea superconducting tokamak advanced research (KSTAR) with electron cyclotron resonance heating (ECH). Ar emission was measured by soft x-ray (SXR) arrays and vacuum UV (VUV) diagnostics. A significant reduction in the core Ar emissivity was observed with core ECH. The reduction was the largest with on-axis heating and became smaller with outward heating positions. The diffusivity and convection velocity of Ar were obtained by analysis of the SXR data with the SANCO impurity transport code for the on-axis ECH and the non-ECH shots. In the on-axis ECH case, both diffusivity and convection velocity increased. Furthermore, the convection changed its direction from inward to outward in the plasma core (r/a < 0.3), resulting in a hollow profile of the total Ar density. Together with the reduction in the SXR signals, the hollow impurity profile in the core and the reversal of the convection velocity consistently confirm that ECH can reduce impurity accumulation in the core region. Neoclassical impurity transport and linear stability of micro-turbulence were calculated and discussed in relation to the possible transport mechanism.

  18. Reduced description of light impurities in hydrogen coronal plasmas

    Directory of Open Access Journals (Sweden)

    D. Kh. Morozov

    2000-01-01

    Full Text Available Se aplica la teor a de impurezas radiativas a plasmas de reactores termonu- cleares, as como a nubes interestelares e intergal acticas, atm osferas estelares y prominencias solares. Las impurezas radiativas son capaces de cambiar la din amica del plasma. Permiten la aparici on de nuevos tipos de equilibrio, de ondas lineales y no-lineales y cambian signi cativamente los criterios de estabilidad. Para una de- scripci on completa de las impurezas, uno necesita un gran conjunto de ecuaciones que describan a cada uno de los estados de ionizaci on. Se muestra que es posible describir impurezas ligeras, con exactitud aceptable, con s olo dos o tres estados representativos de ionizaci on. Se muestra que la descripci on de cinco estados puede reducirse a uno de tres estados de ionizaci on. Se propone un modelo reducido para impurezas ligeras o para impurezas pesadas altamente ionizadas en plasmas coro- nales. Esto permite obtener soluciones anal ticas en muchos casos, reduciendo los tiempos de c omputo. Se deriva un conjunto de ecuaciones simples para determinar la din amica de la distribuci on de impurezas en los diferentes estados de ionizaci on.

  19. The role of MHD in causing impurity peaking in JET Hybrid plasmas

    CERN Document Server

    Hender, T C; Casson, F J; Alper, B; Baranov, Yu; Baruzzo, M; Challis, C D; Koechl, F; Marchetto, C; Nave, M F F; Pütterich, T; Cortes, S Reyes; Contributors, JET

    2015-01-01

    In Hybrid plasma operation in JET with its ITER-like wall (JET-ILW) it is found that n>1 tearing activity can significantly enhance the rate of on-axis peaking of tungsten impurities, which in turn significantly degrades discharge performance. Core n=1 instabilities can be beneficial in removing tungsten impurities from the plasma core (e.g. sawteeth or fishbones), but can conversely also degrade core confinement (particularly in combination with simultaneous n=3 activity). The nature of MHD instabilities in JET Hybrid discharges, with both its previous Carbon wall and subsequent JET-ILW, is surveyed statistically and the character of the instabilities is examined. Possible qualitative models for how the n>1 islands can enhance on-axis tungsten transport accumulation processes are presented.

  20. Dust-Acoustic Waves in Strongly Coupled Dusty Plasmas Containing Variable-Charge Impurities

    Institute of Scientific and Technical Information of China (English)

    XIE Bai-Song; HE Kai-Fen; M. Y. Yu

    2000-01-01

    A relatively self-consistent theory of dust-acoustic waves in the strongly coupled dusty plasmas containing variable charge impurities is given. Relevant physical processes such as dust elastic relaxation and dust charge relaxation are taken into account. It is shown that the negative dispersion of dust-acoustic waves due to the strong correlation of dusts is enhanced in the presence of dust-neutral collisions.

  1. Modeling of limiter heat loads and impurity transport in Wendelstein 7-X startup plasmas

    Science.gov (United States)

    Effenberg, Florian; Feng, Y.; Frerichs, H.; Schmitz, O.; Hoelbe, H.; Koenig, R.; Krychowiak, M.; Pedersen, T. S.; Bozhenkov, S.; Reiter, D.

    2015-11-01

    The quasi-isodynamic stellarator Wendelstein 7-X starts plasma operation in a limiter configuration. The field consists of closed magnetic flux surfaces avoiding magnetic islands in the plasma boundary. Because of the small size of the limiters and the absence of wall-protecting elements in this phase, limiter heat loads and impurity generation due to plasma surface interaction become a concern. These issues are studied with the 3D fluid plasma edge and kinetic neutral transport code EMC3-Eirene. It is shown that the 3D SOL consists of three separate helical magnetic flux bundles of different field line connection lengths. A density scan at input power of 4MW reveals a strong modulation of the plasma paramters with the connection length. The limiter peak heat fluxes drop from 14 MWm-2 down to 10 MWm-2 with raising the density from 1 ×1018m-3 to 1.9 ×1019m-3, accompanied by an increase of the heat flux channel widths λq. Radiative power losses can help to avoid thermal overloads of the limiters at the upper margin of the heating power. The power removal feasibility of the intrinsic carbon and other extrinsic light impurities via active gas injection is discussed as a preparation of this method for island divertor operation. Work supported in part by start up funds of the Department of Engineering Physics at the University of Wisconsin - Madison, USA and by the U.S. Department of Energy under grant DE-SC0013911.

  2. Impurity identifications, concentrations and particle fluxes from spectral measurements of the EXTRAP T2R plasma

    Science.gov (United States)

    Menmuir, S.; Kuldkepp, M.; Rachlew, E.

    2006-10-01

    An absolute intensity calibrated 0.5 m spectrometer with optical multi-channel analyser detector was used to observe the visible-UV radiation from the plasma in the EXTRAP T2R reversed field pinch experiment. Spectral lines were identified indicating the presence of oxygen, chromium, iron and molybdenum impurities in the hydrogen plasma. Certain regions of interest were examined in more detail and at different times in the plasma discharge. Impurity concentration calculations were made using the absolute intensities of lines of OIV and OV measured at 1-2 ms into the discharge generating estimates of the order of 0.2% of ne in the central region rising to 0.7% of ne at greater radii for OIV and 0.3% rising to 0.6% for OV. Edge electron temperatures of 0.5-5 eV at electron densities of 5-10×1011 cm-3 were calculated from the measured relative intensities of hydrogen Balmer lines. The absolute intensities of hydrogen lines and of multiplets of neutral chromium and molybdenum were used to determine particle fluxes (at 4-5 ms into the plasma) of the order 1×1016, 7×1013 and 3×1013 particles cm-2 s-1, respectively.

  3. Oxygen ion impurity in the TEXTOR tokamak boundary plasma observed and analysed by Zeeman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hey, J.D.; Chu, C.C. [Plasma Physics Research Institute, University of Natal, Durban (South Africa)]. E-mails: hey@nu.ac.za; chu@nu.ac.za; Brezinsek, S.; Unterberg, B.; Mertens, Ph. [Institut fuer Plasmaphysik, Forschungszentrum Juelich, Juelich (Germany)]. E-mail: ph.mertens@fz-juelich.de

    2002-03-28

    Oxygen ion impurity radiation is a potential source of inaccuracy in ion temperature determination with the aid of the commonly used C VI transition n=8{yields}n'=7, produced by charge-exchange recombination (CXR) of C{sup 6+} ions, since the corresponding transition in O VI cannot be resolved under typical plasma conditions in the tokamak. In order to demonstrate the possible importance of oxygen ion impurity radiation, we have selected a convenient spectroscopic 'window' (about 8 A wide) containing the major Zeeman components of two prominent lines in the visible (multiplet 1), one emitted by C{sup 2+} and one by O{sup +}. Observations have been performed in this wavelength range, both tangentially and perpendicularly to the magnetic flux surfaces, in the second case with the aid of a special graphite test limiter. Measurements include the case of special plasma discharges in which oxygen gas was introduced from the test limiter. The temperatures of both species are evaluated from the Doppler broadening of the respective Zeeman components, and compared with the results from a model for collisional heating by impact with hot protons (deuterons) in the plasma edge. The spectra and derived results show that impurity identification in tokamak edge plasmas should not be carried out with the aid of spectral lines from highly excited levels populated by CXR, but using lines corresponding to much more species-specific transitions from lower ionization stages. The identification and quantitative analysis should be performed with the aid of carefully measured and calculated Zeeman-(Paschen-Back-) broadened line profiles, since these have features practically unique to the species under investigation. Some allowance may, however, be required for deviation, from a statistical distribution, of population among fine-structure sublevels. (author)

  4. Effect of impurity deposition layer formation on D retention in LHD plasma exposed W

    Directory of Open Access Journals (Sweden)

    Y. Oya

    2016-12-01

    Full Text Available Effect of carbon based mixed-material deposition layer formation on hydrogen isotope retention was studied. The tungsten (W samples were placed at four different positions, namely PI (sputtering erosion dominated area, DP (deposition dominated area, HL (higher heat load area, and ER (erosion dominated area during 2013 plasma experimental campaign in Large Helical Device (LHD at National Institute for Fusion Science (NIFS, Japan and were exposed to ∼ 4000 shots of hydrogen plasma in a 2013 plasma experimental campaign. Most of the sample surface except for ER was covered by a mixed-material deposition layer formed by plasma experimental campaign, which consisted of carbon, but some metal impurities were contained. For ER sample, He bubbles were formed due to long term He discharge cleaning and He plasma experiments during the plasma experimental campaign. The additional 1keV D2+ implantation was performed to evaluated the D retention enhancement by plasma exposure. It was found that both of H and D retentions were clearly increased. In particular, the H retention was controlled by the thickness of the carbon-dominated mixed-material deposition layer, indicating most of the H was trapped by this mixed-material deposition layer. It is concluded that the accumulation of low-Z mixed-material layer on the surface of the first wall is one of key issues for the determination of hydrogen isotope retention in first wall.

  5. Modification of argon impurity transport by electron cyclotron heating in KSTAR H-mode plasmas

    Science.gov (United States)

    Hong, Joohwan; Henderson, S. S.; Kim, Kimin; Seon, C. R.; Song, Inwoo; Lee, H. Y.; Jang, Juhyeok; Park, Jae Sun; Lee, S. G.; Lee, J. H.; Lee, Seung Hun; Hong, Suk-Ho; Choe, Wonho

    2017-03-01

    Experiments with a small amount of Ar gas injection as a trace impurity were conducted in the Korea Superconducting Tokamak Advanced Research (KSTAR) H-mode plasma ({{B}\\text{T}}   =  2.8 T, {{I}\\text{P}}   =  0.6 MA, and {{P}\\text{NBI}}   =  4.0 MW). 170 GHz electron cyclotron resonance heating (ECH) at 600 and 800 kW was focused along the mid-plane with a fixed major radial position of R   =  1.66 m. The emissivity of the Ar16+ (3.949 {\\mathring{\\text{A}}} ) and Ar15+ (353.860 {\\mathring{\\text{A}}} ) spectral lines were measured by x-ray imaging crystal spectroscopy (XICS) and a vacuum UV (VUV) spectrometer, respectively. ECH reduces the peak Ar15+ emission and increases the Ar16+ emission, an effect largest with 800 kW. The ADAS-SANCO impurity transport code was used to evaluate the Ar transport coefficients. It was found that the inward convective velocity found in the plasma core without ECH was decreased with ECH, while diffusion remained approximately constant resulting in a less-peaked Ar density profile. Theoretical results from the NEO code suggest that neoclassical transport is not responsible for the change in transport, while the microstability analysis using GKW predicts a dominant ITG mode during both ECH and non-ECH plasmas.

  6. Lower limits for parallel impurity fluxes in the PLT edge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, S.A.; Dylla, H.F.

    1978-05-01

    Lower limits for time-resolved anti B-parallel impurity fluxes to solid collectors immersed in the PLT edge plasma have been determined as a function of minor radius. Using geometric shadowing of the probe surface, features attributed to finite ion gyroradii have been observed. Also, for r less than 48 cm, heat pulses of less than 2 ms duration and greater than 2.5 x 10/sup 3/ W/cm/sup 2/ intensity were found to occur at the termination of many discharges.

  7. Influence of impurity and recycling on high-β steady-state plasmas sustained by rotating magnetic fields current drive

    Science.gov (United States)

    Guo, H. Y.; Grossnickle, J. A.; Hoffman, A. L.; Vlases, G. C.

    2009-06-01

    A new upgrade of the Translation, Confinement, and Sustainment (TCS) device, TCSU, has been built to form and sustain high temperature compact toroids (CT), known as Field Reversed Configurations, using Rotating Magnetic Fields (RMF). In TCS the plasma temperature was limited to several 10s of eV due to high impurity content. These impurities are greatly reduced in TCSU by using advanced plasma chamber and helium glow discharge cleaning. Reducing impurity radiation, when coupled with reduced overall recycling, enabled the plasma to enter into a new, collisionless regime with temperatures well over 200 eV, substantially exceeding the radiation barrier. This is a first for CTs at low input power density. This was achieved using the simple even-parity RMF drive (despite transient opening of field lines by the RMF) because the associated energy loss is sheath-limited, coupled with the low edge density resulting from the RMF pinch effect.

  8. Determination of impurity elements in MnZn ferrites by inductively coupled plasma mass spectrometry

    Institute of Scientific and Technical Information of China (English)

    张萍; 符靓; 马俊才; 唐有根

    2015-01-01

    An inductively coupled plasma mass spectrometry (ICP-MS) method was developed for the determination of Na, Mg, Al, K, Ca, Ti, Cr, Co, Ni, Cu, Ga, As, Mo, Ag, Cd and Pb in MnZn ferrites. The sample was digested by HNO3+HCl with microwave digestion followed by dilution with ultrapure water, then the above 16 impurity elements in the solution were analyzed directly by ICP-MS. The impurity elements were introduced by the helium gas or hydrogen gas into the octopole reaction system (ORS) to eliminate the polyatomic interferences caused by the high salty matrixes. The matrix effect was minimized through matrix matching, and Be, Y and Rh were used as internal standard elements. The working parameters of the instrument were optimized. The results show that the method has good precision and high accuracy. The detection limits for the investigated elements are in the range of 0.9−37.5 ng/L, the relative standard deviation of each element is within 1.1%−4.8%, and the recovery of each element is 90%−108%.

  9. Characterization of Impurities in Tokamak Divertor Plasmas from Analysis of Spectral Profiles

    Science.gov (United States)

    Isler, R. C.; Brooks, N. H.; Zaniol, B.

    2002-12-01

    Studies of the production, transport, and radiative losses of impurities in present-day tokamak divertors provide input necessary for the design of future burning- plasma machines. Several types of information rely on detailed analysis of emission profiles. These include ion temperatures, ion flows along field lines, and impurity production mechanisms. Temperatures and flows are determined from Doppler broadening and shifts by comparing measured line shapes to theoretical profiles that include the nonlinear Zeeman/Paschen-Back effect. The two major production mechanisms for atomic carbon are physical and chemical sputtering. These processes can be distinguished by comparing atomic and molecular fluxes, which requires modeling the band emissions of CD and C2. They can also be differentiated from measurements of effective temperatures of C I (best profile fits to thermal distributions). Careful inspection of profiles that give high effective temperatures reveals that they are not actually Gaussian but have asymmetries and shifts that can be correlated to energy distributions expected for physical sputtering. Examples of all these applications are discussed in this review.

  10. Recent theoretical studies of slow collisions between plasma impurity ions and H or He atoms

    Energy Technology Data Exchange (ETDEWEB)

    Fritsch, W. [Hahn-Meitner-Institut Berlin GmbH (Germany). Bereich Theoretische Physik; Tawara, H.

    1997-01-01

    We review recent progress in theoretical studies of slow collisions between light plasma impurity ions and atomic hydrogen or helium. We start with a brief overview of theory work that has been done by various groups in the past. We then proceed to discuss work that is published in the last two years. For the systems of Be{sup 2+}-He, Be{sup 4+}-He and C{sup 5+}-He we present yet unpublished work of our own. All of this work broadens our knowledge about systems that are of interest for the fusion community. Some of the new information is found to be at variance with what is known from other sources and hence needs further analysis. (author)

  11. Effect of impurities on the transition between minority ion and mode conversion ICRH heating in (3He)-H tokamak plasmas

    OpenAIRE

    2013-01-01

    Hydrogen majority plasmas will be used in the initial non-activated phase of ITER operation. Optimizing ion cyclotron resonance heating (ICRH) in such scenarios will help in achieving H-mode in these plasmas. Past JET experiments with the carbon wall revealed a significant impact of intrinsic impurities on the ICRH performance in (3He)-H plasmas relevant for the full-field initial ITER phase. High plasma contamination with carbon impurities resulted in the appearance of a supplementary mode c...

  12. Gyrokinetic study of turbulent convection of heavy impurities in tokamak plasmas at comparable ion and electron heat fluxes

    Science.gov (United States)

    Angioni, C.; Bilato, R.; Casson, F. J.; Fable, E.; Mantica, P.; Odstrcil, T.; Valisa, M.; ASDEX Upgrade Team; Contributors, JET

    2017-02-01

    In tokamaks, the role of turbulent transport of heavy impurities, relative to that of neoclassical transport, increases with increasing size of the plasma, as clarified by means of general scalings, which use the ITER standard scenario parameters as reference, and by actual results from a selection of discharges from ASDEX Upgrade and JET. This motivates the theoretical investigation of the properties of the turbulent convection of heavy impurities by nonlinear gyrokinetic simulations in the experimentally relevant conditions of comparable ion and electron heat fluxes. These conditions also correspond to an intermediate regime between dominant ion temperature gradient turbulence and trapped electron mode turbulence. At moderate plasma toroidal rotation, the turbulent convection of heavy impurities, computed with nonlinear gyrokinetic simulations, is found to be directed outward, in contrast to that obtained by quasi-linear calculations based on the most unstable linear mode, which is directed inward. In this mixed turbulence regime, with comparable electron and ion heat fluxes, the nonlinear results of the impurity transport can be explained by the coexistence of both ion temperature gradient and trapped electron modes in the turbulent state, both contributing to the turbulent convection and diffusion of the impurity. The impact of toroidal rotation on the turbulent convection is also clarified.

  13. Impurity seeding in ITER DT plasmas in a carbon-free environment

    Energy Technology Data Exchange (ETDEWEB)

    Pacher, H.D., E-mail: pacher@emt.inrs.ca [INRS-EMT, Varennes, Québec (Canada); Kukushkin, A.S., E-mail: andre.kukushkin@iter.org [ITER Organization, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Pacher, G.W. [1845 Gray, St. Bruno, QC J3V 4G4 (Canada); Kotov, V. [FZ Jülich, Jülich (Germany); Pitts, R.A. [ITER Organization, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Reiter, D. [FZ Jülich, Jülich (Germany)

    2015-08-15

    Impurity seeding has been studied for a carbon-free divertor configuration in ITER using edge/divertor SOLPS code simulations. For high power DT operation, simulations have been performed for varying throughput, power, pumping speed, impurity seeding concentration and species and the results have been parameterised. With these scalings as boundary conditions, core simulations have determined the operating window for carbon-free, impurity-seeded operation.

  14. A new ICRF scenario for bulk ion heating in D-T plasmas: How to utilize intrinsic impurities in fusion devices in our favour

    CERN Document Server

    Kazakov, Y O; Van Eester, D; Bilato, R; Dumont, R; Lerche, E; Mantsinen, M; Messiaen, A

    2015-01-01

    A fusion reactor requires plasma pre-heating before the rate of deuterium-tritium fusion reactions becomes significant. In ITER, radiofrequency (RF) heating of 3He ions, additionally puffed into the plasma, is one of the main options considered for increasing bulk ion temperature during the ramp-up phase of the pulse. In this paper, we propose an alternative scenario for bulk ion heating with RF waves, which requires no extra 3He puff and profits from the presence of intrinsic Beryllium impurities in the plasma. The discussed method to heat Be impurities in D-T plasmas is shown to provide an even larger fraction of fuel ion heating.

  15. Variable Charge State Impurities in Coupled Kinetic Plasma-Kinetic Neutral Transport Simulations

    Science.gov (United States)

    Stotler, D. P.; Hager, R.; Kim, K.; Koskela, T.; Park, G.

    2015-11-01

    A previous version of the XGC0 neoclassical particle transport code with two fully stripped impurity species was used to study kinetic neoclassical transport in the DIII-D H-mode pedestal. To properly simulate impurities in the scrape-off layer and divertor and to account for radiative cooling, however, the impurity charge state distributions must evolve as the particles are transported into regions of different electron temperatures and densities. To do this, the charge state of each particle in XGC0 is included as a parameter in the list that represents the particle's location in phase space. Impurity ionizations and recombinations are handled with a dedicated collision routine. The associated radiative cooling is accumulated during the process and applied to the electron population later in the time step. The density profiles of the neutral impurities are simulated with the DEGAS 2 neutral transport code and then used as a background for electron impact ionization in XGC0 via a test particle Monte Carlo method analogous to that used for deuterium. This work supported by US DOE contracts DE-AC02-09CH11466.

  16. Interaction of Impurity (Li, Be, B and C)and Hydrogen Isotope Pellet Injection with Reactor-relevant Plasmas

    Institute of Scientific and Technical Information of China (English)

    Deng Baiquan(邓柏权); J.P.Allain; Peng Lilin(彭利林); Wang Xiaoyu(王晓宇); Chen Zhi(陈志); Yan Jiancheng(严建成)

    2005-01-01

    Based on the two-dimensional kinetic ablation theory of the hydrogen pellet ablation developed by Kuteev [B.V. Kuteev, Nuclear Fusion, 35 (1995) 431], an algorithm of erosion speed and ablation rate calculations for Li, Be, and B impurity pellets in reactor-relevant plasma has been derived. Results show compatibilities of lithium pellet injection used in α-particle diagnostics are positive in comparison with other solid impurity pellets (e.g. Be, B and C). Using the 2-D Kuteev lentil model, including kinetic effects, we find that currently existing pellet injection techniques will not meet core-fueling requirements for ITER-FEAT. A pressure as high as 254 MPa must be applied to a pellet accelerator with a 200 cm-long single-stage pneumatic gun, in order to accelerate a pellet with a radius rp0 =0.5 cm to a velocity of Vp0, 24×105 cm/s penetrating 100 cm into the ITER plasma core. Comparisons of pellet velocity- and radius-dependent penetration depth between the Neutral Gas Shielding and the Kuteev's models are made. However, we find that the isotopic effects can lead to a 33% lower pellet speed for solid DT, compared to an identical H2 pellet penetrating the same length in ITER-FEAT plasma, and our calculations show that HFS injection will much improve core fueling efficiency.

  17. Burning the DT-plasma with inert impurities and non-cryogenic ICF-target with solid fuel

    OpenAIRE

    Gus'kov S.Yu.; Il'in D.V.; Sherman V.E.

    2013-01-01

    The ignition criterion, ignition energy and gain of DT-plasma of ICF-target in the presence of impurities of light atoms such as beryllium, carbon and lithium at their arbitrary concentration are found. It is shown that the most promising type of non-cryogenic solid thermonuclear fuel is DT-hydride of beryllium (BeDT). It is suggested to apply the targets with such a fuel as: (1) Fast-ignited ICF-target at the ignition energy of 25–50 kJ and compression driver energy of 2–3 MJ; (2) ICF-target...

  18. Effect of impurities on the transition concentration of helium-3 ions in (3He)-H tokamak plasmas heated with ICRH

    CERN Document Server

    Kazakov, Ye O; Van Eester, D

    2013-01-01

    Hydrogen majority plasmas will be used in the initial non-activated phase of ITER operation. Optimizing ion cyclotron resonance heating (ICRH) in such scenarios will help in achieving H-mode in these plasmas. Past JET experiments with the carbon wall revealed a significant impact of intrinsic impurities on the ICRH performance in (3He)-H plasmas. High plasma contamination with carbon impurities resulted in the appearance of a supplementary mode conversion layer and significant reduction in the transition concentration of 3He minority ions, defined as the concentration at which the change from minority heating to mode conversion regime occurs. In view of the installation of the new ITER-like wall at JET, it is important to evaluate the effect of Be and W impurities on ICRH scenarios in (3He)-H plasmas. In this paper, an approximate analytical expression for the transition concentration of 3He minority ions is derived as a function of plasma and ICRH parameters, and accounting for typical impurity species at JE...

  19. Test of prototype ITER vacuum ultraviolet spectrometer and its application to impurity study in KSTAR plasmas.

    Science.gov (United States)

    Seon, C R; Hong, J H; Jang, J; Lee, S H; Choe, W; Lee, H H; Cheon, M S; Pak, S; Lee, H G; Biel, W; Barnsley, R

    2014-11-01

    To optimize the design of ITER vacuum ultraviolet (VUV) spectrometer, a prototype VUV spectrometer was developed. The sensitivity calibration curve of the spectrometer was calculated from the mirror reflectivity, the grating efficiency, and the detector efficiency. The calibration curve was consistent with the calibration points derived in the experiment using the calibrated hollow cathode lamp. For the application of the prototype ITER VUV spectrometer, the prototype spectrometer was installed at KSTAR, and various impurity emission lines could be measured. By analyzing about 100 shots, strong positive correlation between the O VI and the C IV emission intensities could be found.

  20. Burning the DT-plasma with inert impurities and non-cryogenic ICF-target with solid fuel

    Directory of Open Access Journals (Sweden)

    Gus'kov S.Yu.

    2013-11-01

    Full Text Available The ignition criterion, ignition energy and gain of DT-plasma of ICF-target in the presence of impurities of light atoms such as beryllium, carbon and lithium at their arbitrary concentration are found. It is shown that the most promising type of non-cryogenic solid thermonuclear fuel is DT-hydride of beryllium (BeDT. It is suggested to apply the targets with such a fuel as: (1 Fast-ignited ICF-target at the ignition energy of 25–50 kJ and compression driver energy of 2–3 MJ; (2 ICF-target spark-ignited by 15–20 MJ heavy ion driver; (3 Spark-ignited target by 5–7 MJ laser as a neutron source for hybrid fusion-fission.

  1. Direct Determination of Trace Impurities in High Purity Zinc Oxide by High Resolution Inductively Coupled Plasma Mass Spectrometry

    Institute of Scientific and Technical Information of China (English)

    XIE Hualin; NIE Xidu; LI Libo; SONG Chuhua

    2006-01-01

    The determination of trace impurities in high purity zinc oxide by high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) was investigated. To overcome some potentially problematic spectral interference, measurements were acquired in both middle and high resolution modes. The matrix effects due to the presence of excess HCl and zinc were evaluated. The optimum conditions for the determination were tested and discussed. The standard addition method was employed for quantitative analysis. The detection limits ranged from 0.02 μg/g to 6 μg/g depending on the elements.The experimental results for the determination of Na, Mg, Ca, Cr, Mn, Fe, Co, Ni, Cu, Mo, Cd, Sb and Pb in several high purity zinc oxide powders were presented.

  2. A new ion cyclotron range of frequency scenario for bulk ion heating in deuterium-tritium plasmas: How to utilize intrinsic impurities in our favour

    Energy Technology Data Exchange (ETDEWEB)

    Kazakov, Ye. O.; Ongena, J.; Van Eester, D.; Lerche, E.; Messiaen, A. [Laboratory for Plasma Physics, LPP-ERM/KMS, EUROfusion Consortium Member, Brussels (Belgium); Bilato, R. [Max-Planck-Institut für Plasmaphysik, Garching (Germany); Dumont, R. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Mantsinen, M. [Catalan Institution for Research and Advanced Studies, Barcelona (Spain); Barcelona Supercomputing Center (BSC), Barcelona (Spain)

    2015-08-15

    A fusion reactor requires plasma pre-heating before the rate of deuterium-tritium fusion reactions becomes significant. In ITER, radio frequency (RF) heating of {sup 3}He ions, additionally puffed into the plasma, is one of the main options considered for increasing bulk ion temperature during the ramp-up phase of the pulse. In this paper, we propose an alternative scenario for bulk ion heating with RF waves, which requires no extra {sup 3}He puff and profits from the presence of intrinsic Beryllium impurities in the plasma. The discussed method to heat Be impurities in D-T plasmas is shown to provide an even larger fraction of fuel ion heating.

  3. Local thermodynamic equilibrium modeling of ionization of impurities in argon inductively coupled plasma

    Energy Technology Data Exchange (ETDEWEB)

    Serapinas, Petras, E-mail: serapinas@pfi.l [Institute of Theoretical Physics and Astronomy, Vilnius University, A. Gostauto 12, 01108 Vilnius (Lithuania); Salkauskas, Julius; Ezerinskis, Zilvinas; Acus, Arturas [Institute of Theoretical Physics and Astronomy, Vilnius University, A. Gostauto 12, 01108 Vilnius (Lithuania)

    2010-01-15

    Essentially higher ionization degree of small concentrations of elements in inductively coupled plasma in comparison to the ionization of pure elements is emphasized. This conclusion is used to determine the relative dependence of the sensitivity of the inductively coupled plasma mass spectrometer on the atomic mass. The possibility of evaluation of the ionization temperature and electron density from mass spectrometric signals is proposed. Temperatures about 7000 K and 8000 K were obtained from the ionization ratio dependences on ionization potentials. Electron densities of the order of magnitude 10{sup 15} cm{sup -3}, in excess to the local thermodynamic equilibrium values, follow from the application of the Saha equation to the measurement results and indicate the recombining character of the plasma in the mass spectrometer measurement region. Effects due to additional ionization from matrix were discussed. The effect is largest on minor abundant ionization state components. Matrix effect is restricted to some temperature interval, which depends on the whole matrix composition and the plasma state. The results show that the local thermodynamic equilibrium modeling, if adequately matching the sample composition, can be useful as a quantitative basis for both description of the plasma state and indication of the character of the nonequilibrium effects.

  4. Large amplitude solitary waves in ion-beam plasmas with charged dust impurities

    CERN Document Server

    Misra, A P

    2011-01-01

    The nonlinear propagation of large amplitude dust ion-acoustic (DIA) solitary waves (SWs) in an ion-beam plasma with stationary charged dusts is investigated. For typical plasma parameters relevant for experiments [J. Plasma Phys. \\textbf{60}, 69 (1998)], when the beam speed is larger than the DIA speed ($v_{b0}\\gtrsim1.7c_s$), three stable waves, namely the "fast" and "slow" ion-beam modes and the plasma DIA wave are shown to exist. These modes can propagate as SWs in the beam plasmas. However, in the other regime ($c_s0)$ is found to be limited by a critical value which typically depends on $M$, $v_{b0}$ as well as the ion/beam temperature. The conditions for the existence of DIA solitons are obtained and their properties are analyzed numerically in terms of the system parameters. While the system supports both the compressive and rarefactive large amplitude SWs, the small amplitude solitons exist only of the compressive type. The theoretical results may be useful for observation of soliton excitations in l...

  5. Multi-energy x-ray detector calibration for Te and impurity density (nZ) measurements of MCF plasmas

    Science.gov (United States)

    Maddox, J.; Pablant, N.; Efthimion, P.; Delgado-Aparicio, L.; Hill, K. W.; Bitter, M.; Reinke, M. L.; Rissi, M.; Donath, T.; Luethi, B.; Stratton, B.

    2016-11-01

    Soft x-ray detection with the new "multi-energy" PILATUS3 detector systems holds promise as a magnetically confined fusion (MCF) plasma diagnostic for ITER and beyond. The measured x-ray brightness can be used to determine impurity concentrations, electron temperatures, ne 2 Z eff products, and to probe the electron energy distribution. However, in order to be effective, these detectors which are really large arrays of detectors with photon energy gating capabilities must be precisely calibrated for each pixel. The energy-dependence of the detector response of the multi-energy PILATUS3 system with 100 K pixels has been measured at Dectris Laboratory. X-rays emitted from a tube under high voltage bombard various elements such that they emit x-ray lines from Zr-Lα to Ag-Kα between 1.8 and 22.16 keV. Each pixel on the PILATUS3 can be set to a minimum energy threshold in the range from 1.6 to 25 keV. This feature allows a single detector to be sensitive to a variety of x-ray energies, so that it is possible to sample the energy distribution of the x-ray continuum and line-emission. PILATUS3 can be configured for 1D or 2D imaging of MCF plasmas with typical spatial energy and temporal resolution of 1 cm, 0.6 keV, and 5 ms, respectively.

  6. Ionization balance of impurities in turbulent scrape-off layer plasmas I: local ionization-recombination equilibrium

    Science.gov (United States)

    Guzman, F.; Marandet, Y.; Tamain, P.; Bufferand, H.; Ciraolo, G.; Ghendrih, Ph; Guirlet, R.; Rosato, J.; Valentinuzzi, M.

    2015-12-01

    In magnetized fusion devices, cross field impurity transport is often dominated by turbulence, in particular in the scrape-off layer. In these outer regions of the plasma, fluctuations of plasma parameters can be comparable to mean values, and the way ionization and recombination sources are treated in transport codes becomes questionnable. In fact, sources are calculated using the mean density and temperature values, with no account of fluctuations. In this work we investigate the modeling uncertainties introduced by this approximation, both qualitatively and quantitatively for the local ionization equilibrium. As a first step transport effects are neglected, and their role will be discussed in a companion paper. We show that temperature fluctuations shift the ionization balance towards lower temperatures, essentially because of the very steep temperature dependence of the ionization rate coefficients near the threshold. To reach this conclusion, a thorough analysis of the time scales involved is carried out, in order to devise a proper way of averaging over fluctuations. The effects are found to be substantial only for fairly large relative fluctuation levels for temperature, that is of the order of a few tens of percents.

  7. An Impurity Emission Survey in the near UV and Visible Spectral Ranges of Electron Cyclotron Heated (ECH) Plasma in the TJ-II Stellarator

    Energy Technology Data Exchange (ETDEWEB)

    McCarthy, K. J.; Zurro, B.; Baciero, A.

    2001-07-01

    We report on a near-ultraviolet and visible spectroscopic survey (220-600 nm) of electron cyclotron resonance (ECR) heated plasmas created in the TJ-II stellarator, with central electron temperatures up to 2 keV and central electron densities up to 1.7 x 10 ''19 m''-3. Approximately 1200 lines from thirteen elements have been identified. The purpose of the work is to identify the principal impurities and spectral lines present in TJ-II plasmas, as well as their possible origin to search for transitions from highly ionised ions. This work will act as a base for identifying suitable transitions for following the evolution of impurities under different operating regimens and multiplet systems for line polarisation studies. It is intended to use the database creates as a spectral line reference for comparing spectra under different operating and plasma heating regimes. (Author)

  8. The impact of low-Z impurities on x-ray conversion efficiency from laser-produced plasmas of low-density gold foam targets

    Science.gov (United States)

    Dong, Yunsong; Shang, Wanli; Yang, Jiamin; Zhang, Lu; Zhang, Wenhai; Li, Zhichao; Guo, Liang; Zhan, Xiayu; Du, Huabing; Deng, Bo; Pu, Yikang

    2013-12-01

    It is an important approach to improve the x-ray conversion efficiency of laser-ablated high-Z plasmas by using low initial density materials for various applications. However, unavoidable low-Z impurities in the manufacture process of low-density high-Z foam targets will depress this effect. A general easy-to-use analytical model based on simulations was developed to evaluate the quantitative impact of impurities within the gold foam target on laser to x-ray conversion efficiency. In addition, the x-ray conversion efficiencies of 1 g/cm3 gold foams with two different initial contents of impurities were experimentally investigated. Good agreements have been achieved between the model results and experiments.

  9. Impurity line emission due to thermal charge exchange in JET edge plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Maggi, C.F.; Horton, L.D.; Koenig, R.; Stamp, M. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Summers, H.P. [Strathclyde Univ., Glasgow (United Kingdom)

    1994-07-01

    High n-shell emission from hydrogen-like carbon (C VI, n=8-7) has been routinely observed from the plasma edge of JET. By comparing the measured spectral line intensities with the signals predicted by advanced atomic physics modelling of carbon and hydrogen radiation, integrated with modelling of the divertor and edge plasma, it is concluded that charge transfer from excited state hydrogen donors into fully stripped carbon ions can account for the observed spectral emission, but that the hydrogen distribution and to a lesser extent the carbon distribution away from the strike zone predicted by the transport model are too low. Data presented are those of three upper X-point discharges, where the target material was carbon. 5 refs., 1 fig., 3 tabs.

  10. Quantification of Trace Amounts of Impurities in High Purity Cobalt by High Resolution Inductively Coupled Plasma Mass Spectrometry

    Institute of Scientific and Technical Information of China (English)

    Hua Lin XIE; Xi Du NIE; You Gen TANG

    2006-01-01

    An analytical method using high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) for rapid simultaneous determination of Be, Mg, Al, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, As, Se, Mo, Ag, Cd, Sn, Sb, Ba, Pt, Au and Pb in high purity cobalt was described. Sample digestions were performed in closed microwave vessels using HNO3 and HCl. The matrix effects due to thc presence of excess HCl and Co were evaluated. The usefulness of high mass resolution for overcoming some spectral interference was demonstrated. The optimum conditions for the determination was tested and discussed. Correction for matrix effects, Sc, Rh and Bi were used as internal standards. The detection limits is 0.003-0.57 μg/g, the recovery ratio is 92.2%- 111.2%, and the RSD is less than 3.6%. The method is accurate, quick and convenient. It has been applied to the determination of trace impurities in high purity cobalt with satisfactory results.

  11. Quantification of trace amounts of impurities in high purity cobalt by high resolution inductively coupled plasma mass spectrometry

    Institute of Scientific and Technical Information of China (English)

    XIE Hualin; HUANG Kelong; NIE Xidu; TANG Yougen

    2007-01-01

    An analytical method using high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) for rapid simultaneous determination of 24 elements (Be, Mg, Al, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Ge, As, Se, Mo, Ag, Cd, Sn,Sb, Ba, Pt, Au, and Pb) in high purity cobalt was described. Sample digestions were performed in closed microwave vessels using HNO3 and HCl. The matrix effects because of the presence of excess HCl and Co were evaluated. The usefulness of high mass resolution for overcoming some spectral interference was demonstrated. The optimum conditions for the determination were tested and discussed. The standard addition method was employed for quantitative analysis. The detection limits were 0.016-1.50 μg.g-1, the recovery ratios were 92.2%-111.2%, and the RSD was less than 3.6%. The method was accurate, quick, and convenient. It was applied to the determination of trace impurities in high purity cobalt with satisfactory results.

  12. An evaluation of microwave-assisted fusion and microwave-assisted acid digestion methods for determining elemental impurities in carbon nanostructures using inductively coupled plasma optical emission spectrometry

    KAUST Repository

    Patole, Shashikant P.

    2015-10-21

    It is common for as-prepared carbon nanotube (CNT) and graphene samples to contain remnants of the transition metals used to catalyze their growth; contamination may also leave other trace elemental impurities in the samples. Although a full quantification of impurities in as-prepared samples of carbon nanostructures is difficult, particularly when trace elements are intercalated or encapsulated within a protective layer of graphitic carbon, reliable information is essential for reasons such as quantifying the adulteration of physico-chemical properties of the materials and for evaluating environmental issues. Here, we introduce a microwave-based fusion method to degrade single- and double-walled CNTs and graphene nanoplatelets into a fusion flux thereby thoroughly leaching all metallic impurities. Subsequent dissolution of the fusion product in diluted hydrochloric and nitric acid allowed us to identify their trace elemental impurities using inductively coupled plasma optical emission spectrometry. Comparisons of the results from the proposed microwave-assisted fusion method against those of a more classical microwave-assisted acid digestion approach suggest complementarity between the two that ultimately could lead to a more reliable and less costly determination of trace elemental impurities in carbon nanostructured materials. Graphical abstract A method for the complete digestion of carbon nanostructures has been demonstrated. Photographs (on the left side) show zirconium crucibles containing SWCNTs with flux of Na2CO3 and K2CO3, before and after microwave fusion; (on the right side) the appearance of the final solutions containing dissolved samples, from microwave-assisted fusion and microwave-assisted acid digestion. These solutions were used for determining the trace elemental impurities by ICP‒OES.

  13. Microfield dynamics in dense hydrogen plasmas with high-Z impurities

    Science.gov (United States)

    Hau-Riege, Stefan P.; Weisheit, Jon

    2017-01-01

    We use large-scale classical molecular dynamics to determine microfield properties for several dense plasma mixtures. By employing quantum statistical potentials (QSPs) to regularize the Coulomb interaction, our simulations follow motions of electrons as well as ions for times long enough to track relaxation phenomena involving both types of particles. Coulomb coupling, relative to temperature, of different pairs of species in the hot, dense matter being simulated ranges from weak to strong. We first study the effect of such coupling differences, along with composition and QSP differences, on the roles of electrons and various mixture components in determining probability distributions of instantaneous, total microfields experienced by the ions. Then, we address two important dynamical questions: (1) How is the quasistatic part of the total field to be extracted from the time-dependent simulation data? (2) Under what conditions does the commonly used approximation of ions with fixed Yukawa-like screening by free electrons accurately describe quasistatic fields? We identify a running, short-time average of the total field at each ion as its slowly evolving, quasistatic part. We consider several ways to specify the averaging interval, and note the influence of ion dynamics in this issue. When all species are weakly coupled, the quasistatic fields have probability distributions agreeing well with those we obtain from simulations of Yukawa-screened ions. However, agreement deteriorates as the coupling between high-Z ions increases well beyond unity, principally because the Yukawa model tends to underestimate the true screening of close high-Z pairs. Examples of this fact are given, and some consequences for the high-field portions of probability distributions are discussed.

  14. Fluid-particle hybrid simulation on the transports of plasma, recycling neutrals, and carbon impurities in the Korea Superconducting Tokamak Advanced Research divertor region

    Science.gov (United States)

    Kim, Deok-Kyu; Hong, Sang Hee

    2005-06-01

    A two-dimensional simulation modeling that has been performed in a self-consistent way for analysis on the fully coupled transports of plasma, recycling neutrals, and intrinsic carbon impurities in the divertor domain of tokamaks is presented. The numerical model coupling the three major species transports in the tokamak edge is based on a fluid-particle hybrid approach where the plasma is described as a single magnetohydrodynamic fluid while the neutrals and impurities are treated as kinetic particles using the Monte Carlo technique. This simulation code is applied to the KSTAR (Korea Superconducting Tokamak Advanced Research) tokamak [G. S. Lee, J. Kim, S. M. Hwang et al., Nucl. Fusion 40, 575 (2000)] to calculate the peak heat flux on the divertor plate and to explore the divertor plasma behavior depending on the upstream conditions in its base line operation mode for various values of input heating power and separatrix plasma density. The numerical modeling for the KSTAR tokamak shows that its full-powered operation is subject to the peak heat loads on the divertor plate exceeding an engineering limit, and reveals that the recycling zone is formed in front of the divertor by increasing plasma density and by reducing power flow into the scrape-off layer. Compared with other researchers' work, the present hybrid simulation more rigorously reproduces severe electron pressure losses along field lines by the presence of recycling zone accounting for the transitions between the sheath limited and the detached divertor regimes. The substantial profile changes in carbon impurity population and ionic composition also represent the key features of this divertor regime transition.

  15. Modelling of impurity transport and plasma-wall interaction in fusion devices with the ERO code: basics of the code and examples of application

    Energy Technology Data Exchange (ETDEWEB)

    Kirschner, A.; Borodin, D.; Brezinsek, S.; Linsmeier, C.; Romazanov, J. [Forschungszentrum Juelich GmbH, Institut fuer Energie- und Klimaforschung - Plasmaphysik, Juelich (Germany); Tskhakaya, D. [Fusion rate at OeAW, Institute of Applied Physics, TU Wien (Austria); Institute of Theoretical Physics, University of Innsbruck (Austria); Kawamura, G. [National Institute for Fusion Science, Gifu (Japan); Ding, R. [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, Anhui (China)

    2016-08-15

    The 3D ERO code, which simulates plasma-wall interaction and impurity transport in magnetically confined fusion-relevant devices is described. As application, prompt deposition of eroded tungsten has been simulated at surfaces with shallow magnetic field of 3 T. Dedicated PIC simulations have been performed to calculate the characteristics of the sheath in front of plasma-exposed surfaces to use as input for these ERO simulations. Prompt deposition of tungsten reaches 100% at the highest electron temperature and density. In comparison to more simplified assumptions for the sheath the amount of prompt deposition is in general smaller if the PIC-calculated sheath is used. Due to friction with the background plasma the impact energy of deposited tungsten can be significantly larger than the energy gained in the sheath potential. (copyright 2016 The Authors. Contributions to Plasma Physics published by Wiley-VCH Verlag GmbH and Co. KGaA Weinheim. This)

  16. Standard test method for the determination of impurities in plutonium metal: acid digestion and inductively coupled plasma-mass spectroscopy (ICP-MS) analysis

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2006-01-01

    1.1 This Test Method covers the determination of 58 trace elements in plutonium (Pu) metal. The Pu sample is dissolved in acid, and the concentration of the trace impurities are determined by Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS). 1.2 This Test Method is specific for the determination of trace impurities in Pu metal. It may be applied to other types of Pu materials, such as Pu oxides, if the samples are dissolved and oxidized to the Pu(IV) state. However, it is the responsibility of the user to evaluate the performance of other matrices. 1.3 This standard does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this method to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use of this standard.

  17. Three-dimensional simulation of H-mode plasmas with localized divertor impurity injection on Alcator C-Mod using the edge transport code EMC3-EIRENE

    Energy Technology Data Exchange (ETDEWEB)

    Lore, J. D., E-mail: lorejd@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Reinke, M. L.; Lipschultz, B. [York Plasma Institute, Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom); Brunner, D.; LaBombard, B.; Terry, J. [Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139 (United States); Pitts, R. A. [ITER Organization, Route de Vinon-sur-Verdon, CS 90046 - 13067 Saint Paul Lez Durance Cedex (France); Feng, Y. [Max Planck Institute for Plasma Physics, Greifswald (Germany)

    2015-05-15

    Experiments in Alcator C-Mod to assess the level of toroidal asymmetry in divertor conditions resulting from poloidally and toroidally localized extrinsic impurity gas seeding show a weak toroidal peaking (∼1.1) in divertor electron temperatures for high-power enhanced D-alpha H-mode plasmas. This is in contrast to similar experiments in Ohmically heated L-mode plasmas, which showed a clear toroidal modulation in the divertor electron temperature. Modeling of these experiments using the 3D edge transport code EMC3-EIRENE [Y. Feng et al., J. Nucl. Mater. 241, 930 (1997)] qualitatively reproduces these trends, and indicates that the different response in the simulations is due to the ionization location of the injected nitrogen. Low electron temperatures in the private flux region (PFR) in L-mode result in a PFR plasma that is nearly transparent to neutral nitrogen, while in H-mode the impurities are ionized in close proximity to the injection location, with this latter case yielding a largely axisymmetric radiation pattern in the scrape-off-layer. The consequences for the ITER gas injection system are discussed. Quantitative agreement with the experiment is lacking in some areas, suggesting potential areas for improving the physics model in EMC3-EIRENE.

  18. Metal impurity transport control in JET H-mode plasmas with central ion cyclotron radiofrequency power injection

    DEFF Research Database (Denmark)

    Valisa, M.; Carraro, L.; Predebon, I.

    2011-01-01

    The scan of ion cyclotron resonant heating (ICRH) power has been used to systematically study the pump out effect of central electron heating on impurities such as Ni and Mo in H-mode low collisionality discharges in JET. The transport parameters of Ni and Mo have been measured by introducing a t...

  19. Slurry sampling fluorination assisted electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry for the direct determination of metal impurities in aluminium oxide ceramic powders.

    Science.gov (United States)

    Peng, T; Chang, G; Wang, L; Jiang, Z; Hu, B

    2001-03-01

    A new analytical procedure for the direct determination of metal impurities (Cr, Cu, Fe and V) in aluminium oxide ceramic powders by slurry sampling fluorination assisted electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry (ETV-ICP-AES) is reported. A polytetrafluoroethylene (PTFE) emulsion was used as a fluorinating reagent to promote the vaporization of impurity elements in aluminium oxide ceramic powders from the graphite tube. A vaporization stage with a long ramp time and a short hold time provided the possibility of temporal analyte-matrix separation. The experimental results indicated that a 10 microL 1% m/v slurry of aluminium oxide could be destroyed and vaporized completely with 600 micrograms PTFE under the selected conditions. Two aluminium oxide ceramic powder samples were used without any additional pretreatment. Analytical results obtained by using standard addition method with aqueous standard solution were checked by comparison of the results with pneumatic nebulization (PN)-ICP-AES based on the wet-chemical decomposition and analyte-matrix separation. The limits of detection (LODs) between 0.30 microgram g-1 (Fe) and 0.08 microgram g-1 (Cu) were achieved, and, the repeatability of measurements was mainly better than 10%.

  20. Particle in cell/Monte Carlo collision analysis of the problem of identification of impurities in the gas by the plasma electron spectroscopy method

    Science.gov (United States)

    Kusoglu Sarikaya, C.; Rafatov, I.; Kudryavtsev, A. A.

    2016-06-01

    The work deals with the Particle in Cell/Monte Carlo Collision (PIC/MCC) analysis of the problem of detection and identification of impurities in the nonlocal plasma of gas discharge using the Plasma Electron Spectroscopy (PLES) method. For this purpose, 1d3v PIC/MCC code for numerical simulation of glow discharge with nonlocal electron energy distribution function is developed. The elastic, excitation, and ionization collisions between electron-neutral pairs and isotropic scattering and charge exchange collisions between ion-neutral pairs and Penning ionizations are taken into account. Applicability of the numerical code is verified under the Radio-Frequency capacitively coupled discharge conditions. The efficiency of the code is increased by its parallelization using Open Message Passing Interface. As a demonstration of the PLES method, parallel PIC/MCC code is applied to the direct current glow discharge in helium doped with a small amount of argon. Numerical results are consistent with the theoretical analysis of formation of nonlocal EEDF and existing experimental data.

  1. Sintering of ZrC by hot isostatic pressing (HIP) and spark plasma sintering (SPS). Effect of impurities

    Energy Technology Data Exchange (ETDEWEB)

    Allemand, Alexandre [CEA Saclay, DRT/DTEN/S3ME/LTMEx, 91191 Gif-sur-Yvette (France); Le Flem - Dormeval, Marion [CEA Saclay, DEN/DMN/SRMA/LA2M, 91191 Gif-sur-Yvette (France); Guillard, Francois [CNRS-CEMES-CMI, 29 rue J.Marving, 31000 Toulouse (France)

    2005-07-01

    Carbides are generally used as structural materials for high temperature applications. Particularly, ZrC because of low activation, neutronic transparency, cubic structure (isotropic behaviour) and good thermal conductivity, is one of the candidates under consideration for structural materials in the core of new high temperature nuclear reactors (Generation IV). Just a few studies about densification of monolithic ZrC exist. They mainly involve natural sintering or hot pressing at high temperature (until 2700 deg. C). Unfortunately those processes induce grain growth and do not lead to fully densified ZrC. The aim of this study is to compare the characteristics and the properties of ZrC sintered by HIP and by SPS. Fully dense ZrC can be reached either by HIP or by SPS, grain size being more or less controlled. Microstructural observations and mechanical testing of several ZrC grades shows that powder impurities play an important role in the quality of the grain boundaries and consequently in the mechanical properties. In particular, the porosity falls from 17% to 3 % just by reducing the free carbon content in starting ZrC powder. The densification process of dense monolithic ZrC was improved by combining a HIP at 1600 deg. C (titanium canning) followed by a post-HIP at 1900 deg. C (no canning required). Four-point bending tests are in progress to confirm the improvement of fracture strength. (authors)

  2. Simulated impurity transport in LHD from MIST

    Energy Technology Data Exchange (ETDEWEB)

    Rice, J.E. [National Inst. for Fusion Science, Toki, Gifu (Japan)

    1998-05-01

    The impurity transport code MIST and atomic physics package LINES are used to calculate the time evolution of charge state density profiles, individual line emissivity profiles and total radiated power profiles for impurities in LHD plasmas. Three model LHD plasmas are considered; a high density, low temperature case, a low density, high temperature case and the initial LHD start-up plasma (500 kW ECH), using impurity transport coefficient profiles from Heliotron E. The elements oxygen, neon, scandium, iron, nickel and molybdenum are considered, both injected and in steady state. (author)

  3. Enhancement of hydrogen isotope retention capacity for the impurity deposited tungsten by long-term plasma exposure in LHD

    Energy Technology Data Exchange (ETDEWEB)

    Oya, Yasuhisa, E-mail: syoya@ipc.shizuoka.ac.jp [Radioscience Research Laboratory, Faculty of Science, Shizuoka University, Shizuoka 422-8529 (Japan); Masuzaki, Suguru; Tokitani, Masayuki [National Institute for Fusion Science, Gifu 509-5292 (Japan); Yoshida, Naoaki; Watanabe, Hideo [Kyushu University, Fukuoka 816-8580 (Japan); Yamauchi, Yuji; Hino, Tomoaki [Hokkaido University, Sapporo 060-8628 (Japan); Miyamoto, Mitsutaka [Shimane University, Shimane 690-8504 (Japan); Hatano, Yuji [University of Toyama, Toyama 930-8555 (Japan); Okuno, Kenji [Radioscience Research Laboratory, Faculty of Science, Shizuoka University, Shizuoka 422-8529 (Japan)

    2013-10-15

    Highlights: • The carbon-dominant mixed-material layer was formed on the tungsten surface after 15{sup th} plasma exposure in LHD. • The largest enhancement of deuterium retention was found to be about 21. • The major deuterium desorption temperature was shifted toward higher temperature side. -- Abstract: The stress relieved tungsten samples were placed at three positions, PI (sputtering erosion dominated area), DP (deposition dominated area) and HL (Higher heat load area) during 15th plasma experiment campaign in Large Helical Device (LHD) at National Institute for Fusion Science (NIFS), Japan and were exposed to ∼ 6700 shots of hydrogen plasma in a 15th long-term experiment campaign in LHD. Thereafter, the additional deuterium ion implantation to these tungsten samples was performed to evaluate the change of hydrogen isotope retention capacity in the samples by long-term plasma exposure. It was found that the carbon-dominant mixed-material layer with more than 100 nm thickness was formed on a wide area of the tungsten surface. The thicker mixed-material layer was formed on the DP sample, where the deuterium retention was about 21 times as high as that for pure W. The major desorption temperature of deuterium was shifted toward higher temperature side, which was comparable to the trapping characteristic of carbon or irradiation damages.

  4. Simultaneous determination of some trace metal impurities in high-purity sodium tungstate using coprecipitation and inductively coupled plasma atomic emission spectrometry

    Institute of Scientific and Technical Information of China (English)

    MA Xiaoguo; KUANG Tongchun; LIU Qianjun

    2004-01-01

    A method based on the combination of coprecipitation with inductively coupled plasma atomic emission spec trometry (ICP-AES) was developed for the determination of impurities in high-purity sodium tungstate. Six elements (Co,Cu, Fe, Mn, Ni, and Pb) were coprecipitated by lanthanum hydroxide so as to be concentrated and separated from the tungsten matrix. Effects of some factors on the recoveries of the analytes and on the residual amount of sodium tungstate were investigated, and the optimum conditions for the coprecipitation were proposed. Matrix-matching calibration curve method was used for the analysis. It is shown that the elements mentioned above can be quantitatively recovered. The detection limits for Co, Cu, Fe, Mn, Ni, and Pb are 0.07, 0.4, 0.2, 0.1, 0.6, and 1.3 μg.g-1, respectively. The recoveries vary from 92.5% to 108%, and the relative standard deviations (RSDs) are in the range of 3.1%-5.5%.

  5. On the role of atomic metastability in the production of Balmer line radiation from ‘cold’ atomic hydrogen, deuterium and hydrogenic ion impurities in fusion edge plasmas

    Science.gov (United States)

    Hey, J. D.

    2012-03-01

    Published arguments, which assign an important role to atomic metastability in the production of ‘narrow’ Zeeman component radiation from the boundary region of fusion plasmas, are examined critically in relation to l-redistribution by proton and electron collisions, and mixing of unperturbed atomic states by the ion microfield and microfield gradient. It is concluded that these important processes indeed severely constrain the contribution from ‘metastable’ states to the generation of the hydrogen Balmer spectra, for electron concentrations above 1012 cm-3, as pointed out before by the present author (Hey et al 1999 J. Phys. B: At. Mol. Opt. Phys. 32 3555). The analysis of collision-induced l-redistribution represents an extension of that used previously (Hey et al 1996 Contrib. Plasma Phys. 36 583), applicable up to higher electron densities. For comparison purposes, we also consider the question of metastability of ionized helium in a low-temperature plasma, and that of some common hydrogenic impurities (C5+ and Ne9+) in a hydrogen (deuterium) fusion plasma. While for low nuclear charge Z the metastability of 2s1/2 levels is quenched by the plasma environment, it is much reduced in high-Z ions owing to the rapid increase with Z of the two-photon electric dipole (2E1) and magnetic dipole (M1) spontaneous transition rates to the ground state, whereas the role of the plasma in these cases is less important. The main new principle elaborated in this work is the sensitivity of atomic line strengths, and hence collision strengths, to perturbation by the plasma environment for transitions between fine-structure sublevels of the same principal quantum number. As the plasma microfield strength grows, ‘allowed’ transitions diminish in strength, while ‘forbidden’ transitions grow. However, owing to violation of the parity selection rule, there is an overall loss of collision strength available to transitions, resulting from the appearance of significant

  6. Investigation of the effects of impurity seeding under different magnetic configurations in L-mode plasma in EAST tokamak

    Science.gov (United States)

    Xiang, Lingyan; Guo, Houyang; Wischmeier, Marco; Wu, Zhenwei; Wang, Liang; Duan, Yanmin; Gan, Kaifu; Shen, Yongcai; Chen, Yingjie; EAST Team

    2017-09-01

    Experiments with a small amount of Ar puffed from the lower outer target into L-mode plasma in double null (DN), lower single null (LSN), and upper single null (USN) configurations studied the effects of magnetic configurations and the seeded location relative to the X-point on the performance of Ar seeding. With Ar seeded, the peak heat flux and the integrated power load onto the target decreased most significantly in the LSN configuration, although the increase of the line integrated radiation in the main plasma was the lowest in this case and the highest in the USN configuration. The radiation fraction in the divertor rose from about 10% to 23% of the heating power in LSN, and from around 15% to 22% in DN, while it almost did not change in the USN configuration with Ar seeding. The line emission of Ar XVI increased following the puff and then started to degrade near the end of LSN and USN phases. No such degradation was seen in the DN phase, meaning that some Ar dwelt in the core till the LSN phase began, which explained the peaking of radiation in the core prior to the seeding in the LSN phase. Dedicate Modeling indicates that the LSN configuration has the highest divertor radiation fraction. The highest radiation from outside the divertor is in the USN configuration. With increasing Ar seeding, the LSN configuration sees an increase of the radiation inside the divertor while in the USN configuration, it is the radiation from outside the divertor that increases most strongly. In the DN configuration, the radiation from both inside and outside the divertor increases with seeding, with the former more strongly.

  7. Neoclassical impurity transport in stellarator geometry

    CERN Document Server

    García-Regaña, J M; Beidler, C D; berg, H Maaß; Helander, P; Turkin, Y

    2012-01-01

    The impurity dynamics in stellarators has become an issue of moderate concern due to the, \\textit{a priori}, inherent tendency of the impurities to accumulate in the core when the neoclassical ambipolar radial electric field points radially inwards (ion root regime). This accumulation can lead to collapse of the plasma due to radiative losses, and thus limit high performance plasma discharges in non-axisymmetric devices. Theoretically, a quantitative description of the neoclassical impurity transport is complicated by the breakdown of the assumption of small $q \\tilde{\\Phi}/T$ for impurities, where $q$ is the electric charge, $T$ the temperature in energy units, and $\\tilde{\\Phi}$ the electrostatic potential variation within the flux surface. The present work describes quantitatively the particle transport of impurities in the frame of local neoclassical theory when $q\\tilde{\\Phi}/T=O(1)$ in the Large Helical Device (LHD) stellarator. %and the Wendelstein 7-X stellarators. The central numerical tool used is t...

  8. Direct determination of impurities in high purity silicon carbide by inductively coupled plasma optical emission spectrometry using slurry nebulization technique.

    Science.gov (United States)

    Wang, Zheng; Qiu, Deren; Ni, Zheming; Tao, Guangyi; Yang, Pengyuan

    2006-09-08

    A novel method for the determination of Al, Ca, Cr, Cu, Fe, Mg, Mn, Ni and Ti in high purity silicon carbide (SiC) using slurry introduction axial viewed inductively coupled plasma optical emission spectrometry (ICP-OES) was described. The various sizes of SiC slurry were dispersed by adding dispersant polyethylene imine (PEI). The stability of slurry was characterized by zeta potential measurement, SEM observation and signal stability testing. The optimal concentration of PEI was found to be 0.5 wt% for the SiC slurry. Analytical results of sub-mum size SiC by the slurry introduction were in good accordance with those by the alkaline fusion method which verified that determination could be calibrated by aqueous standards. For mum size SiC, results of most elements have a negative deviation and should be calibrated by the Certified Reference Material slurry. Owing to a rather low contamination in the sample preparation and stability of the slurry, the limits of detection (LODs), which are in the range of 40-2000 ng g(-1), superior to those of the conventional nebulization technique by ICP-OES or ICP-MS.

  9. Standard test method for determination of impurities in nuclear grade uranium compounds by inductively coupled plasma mass spectrometry

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This test method covers the determination of 67 elements in uranium dioxide samples and nuclear grade uranium compounds and solutions without matrix separation by inductively coupled plasma mass spectrometry (ICP-MS). The elements are listed in Table 1. These elements can also be determined in uranyl nitrate hexahydrate (UNH), uranium hexafluoride (UF6), triuranium octoxide (U3O8) and uranium trioxide (UO3) if these compounds are treated and converted to the same uranium concentration solution. 1.2 The elements boron, sodium, silicon, phosphorus, potassium, calcium and iron can be determined using different techniques. The analyst's instrumentation will determine which procedure is chosen for the analysis. 1.3 The test method for technetium-99 is given in Annex A1. 1.4 The values stated in SI units are to be regarded as standard. 1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish ...

  10. Power Radiated from ITER and CIT by Impurities

    Science.gov (United States)

    Cummings, J.; Cohen, S. A.; Hulse, R.; Post, D. E.; Redi, M. H.; Perkins, J.

    1990-07-01

    The MIST code has been used to model impurity radiation from the edge and core plasmas in ITER and CIT. A broad range of parameters have been varied, including Z{sub eff}, impurity species, impurity transport coefficients, and plasma temperature and density profiles, especially at the edge. For a set of these parameters representative of the baseline ITER ignition scenario, it is seen that impurity radiation, which is produced in roughly equal amounts by the edge and core regions, can make a major improvement in divertor operation without compromising core energy confinement. Scalings of impurity radiation with atomic number and machine size are also discussed.

  11. Behavior of impurities in TRIAM-IM

    Energy Technology Data Exchange (ETDEWEB)

    Takashiri, Masayuki; Nakamura, Kazuo; Kawasaki, Shoji; Jotaki, Eriko; Makino, Kenichi; Ito, Sanae; Ito, Satoshi [Kyushu Univ., Fukuoka (Japan)

    1994-09-01

    This research is the spectroscopic research on the behavior of impurities in the superconducting strong magnetic field tokamak, TRIAM-1M. In the experiment at the TRIAM-1M, the steady operation of the tokamak by the current drive using 8.2 GHz low hybrid waves has been aimed at toward the practical use of nuclear fusion reactors. In this research, the design and manufacture of the spectroscope system for diagnosing the behavior of impurities and the evaluation of the amount of impurities and effective charge number were carried out. The main impurities were metallic impurities of molybdenum, iron and chrome, and light element impurity of oxygen. The spatial distribution measurement was performed by using a multi-channel vacuum ultraviolet spectroscope system for the spectrum line intensity, and the change with time lapse of the radial distribution of impurity amount was derived. As the results, the amounts of iron and chrome which are the impurities of stainless steel system rapidly increased at plasma center in the latter half of discharge. The increase of the molybdenum amount which is the limiter material was small as compared with iron and chrome, and the amount of oxygen impurity hardly changed throughout discharge. The change with time lapse of the effective charge number in radial distribution was from 4 to 6 during discharge. (K.I.).

  12. Impurity sources in TEXTOR

    Science.gov (United States)

    Pospieszczyk, A.; Bay, H. L.; Bogen, P.; Hartwig, H.; Hintz, E.; Konen, L.; Ross, G. G.; Rusbuldt, D.; Samm, U.; Schweer, B.

    1987-02-01

    The deuterium, oxygen and carbon fluxes from the main limiter and the deuterium fluxes from the wall are measured in TEXTOR for an "all carbon" surrounding as a function of central density ne, of applied ICRH-power and of different wall conditions (carbonization). For this purpose, emission spectroscopy both with filter systems and spectrometers has been used. It is found that a major release mechanism for light impurities is via the formation of molecules. Oxygen seems to enter the discharge from the liner via O-D containing molecules, whereas the limiter acts as the main carbon source by the release of hydro-carbons as indicated by the observed CD-band spectra. Both oxygen and carbon fluxes are reduced by about a factor of two after a fresh carbonization. Above a certain critical density the plasma detaches from the limiter and forms a stable discharge with a radiation cooled boundary layer and with a major fraction of particles now reaching the wall instead of the limiter. The critical density rises with decreasing impurity fluxes or with increasing heating powers.

  13. Obtaining of Tokamak Plasma Impurities Emissivities Profiles by Using Matrix Inversion Method%矩阵求逆应用于等离子体杂质体发射率测量的研究

    Institute of Scientific and Technical Information of China (English)

    沈永才; 程飞; 吴义恒

    2016-01-01

    In this paper,process of obtaining impurity emissivity on tokamak plasma has been studied .By using matrix inver-sion, emissivity can be calculated according to brightness of impurity spectral lines .As an example, Mo emissivities have been cal-culated by using this method based on the assumed brightness .%对托卡马克等离子体中获得杂质局部体发射率的过程进行研究,提出了一种采用求逆矩阵的方法进行 A-bel反演,根据弦积分的杂质光亮度分布获得杂质局部体发射率。结合托卡马克装置假象的钼杂质弦积分剖面,采用该方法获得了杂质的体发射率分布。

  14. Investigation of Impurity Ion Transport with Laser Blow-off in HL-2A Tokamak

    Institute of Scientific and Technical Information of China (English)

    CUI Zheng-Ying; DONG Yun-Bo; DENG Wei; YANG Qing-Wei; DING Xuan-Tong; HUANG Yuan; SUN Ping; ZHENG Yong-Zhen; SHI Pei-Lan; LU Jie; FU Bing-Zhong; ZHANG Peng; PAN Yu-Dong

    2006-01-01

    @@ Non-recycling impurities are injected into ohmic HL-2A plasma for the first time. The impurities of titanium and aluminium are injected in the discharges with varying plasma density and current. The convection and diffusion process of the injected impurity ions during the inward phase are qualitatively investigated. The results show that the transport of impurities is much slower in the central region of the plasma than outside of it and that it is greatly enhanced during sawtooth crashes.

  15. DETERMINATION OF IMPURITY ELEMENTS IN ALUMINIUM

    Institute of Scientific and Technical Information of China (English)

    侯小琳; 张永保

    1994-01-01

    Twenty five impurity elements in aluminium applied as reactor material are determined.Titanium and nickel are determined with epithermal neutron activation analysis(NAA),magnesium and silicon by inductance coupling plasma emission spectra(ICP),other elements by thermal NAA.The fission coefficient of uranium is given by an experiment,the interferences of uranium to Ce,Nd,Mo,Zr,La,Sm are subtracted.The detection limits of these methods to all of impurity elements in aluminium are calculated.

  16. Simulating W Impurity Transport in Tokamaks

    Science.gov (United States)

    Younkin, Timothy R.; Green, David L.; Lasa, Ane; Canik, John M.; Wirth, Brian D.

    2016-10-01

    The extreme heat and charged particle flux to plasma facing materials in magnetically confined fusion devices has motivated Tungsten experiments such as the ``W-Ring'' experiment on the DIII-D tokamak to investigate W divertor viability. In this domain, the transport of W impurities from their tile locations to other first-wall tiles is highly relevant to material lifetimes and tokamak operation. Here we present initial results from a simulation of this W transport. Given that sputtered impurities may experience prompt redeposition near the divertor strikepoint, or migrate far from its origin to the midplane, there is a need to track the global, 3-D, impurity redistribution. This is done by directly integrating the 6-D Lorentz equation of motion (plus thermal gradient terms and relevant Monte-Carlo operators) for the impurity ions and neutrals under background plasma parameters determined by the SOLPS edge plasma code. The geometric details of the plasma facing components are represented to a fidelity sufficient to examine the global impurity migration trends with initial work also presented on advanced surface meshing capabilities targeting high fidelity simulation. This work is supported by U.S. DOE Office of Science SciDAC project on plasma-surface interactions under US DOE contract DE-AC05-00OR22725.

  17. Charge dependence of neoclassical and turbulent transport of light impurities on MAST

    CERN Document Server

    Henderson, S S; Casson, F J; Dickinson, D; O'Mullane, M; Patel, A; Roach, C M; Summers, H P; Tanabe, H; Valovic, M

    2015-01-01

    Carbon and nitrogen impurity transport coefficients are determined from gas puff experiments carried out during repeat L-mode discharges on the Mega-Amp Spherical Tokamak (MAST) and compared against a previous analysis of helium impurity transport on MAST. The impurity density profiles are measured on the low-field side of the plasma, therefore this paper focuses on light impurities where the impact of poloidal asymmetries on impurity transport is predicted to be negligible. A weak screening of carbon and nitrogen is found in the plasma core, whereas the helium density profile is peaked over the entire plasma radius.

  18. Impurity Measured by VUV Spectrometer and OMA on HL-2A Tokamak

    Institute of Scientific and Technical Information of China (English)

    崔正英; 王全明; 董贾福; 孙平; 卢杰; 李伟; 王恩耀

    2004-01-01

    Impurity is one of the key issues on a great impact to the quality of tokamak plasma.HL-2A is the first divertor tokamak in China. In this paper the experimental results are presented on impurity through the line emission measurement in the campaign in 2003 under the limiter and divertor configurations. The low-Z impurities such as carbon and oxygen are the most important components in the plasma, but their content are not so high to affect the discharge quality. The high-Z impurities such as copper and ferrum are not essential. The emission intensity of impurity is clearly decreased during the divertor configuration formed.

  19. Impurity radiation in DEMO systems modelling

    Energy Technology Data Exchange (ETDEWEB)

    Lux, H., E-mail: Hanni.Lux@ccfe.ac.uk [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Kemp, R.; Ward, D.J. [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Sertoli, M. [Max-Planck-Institut für Plasma Physik, D-85748 Garching (Germany)

    2015-12-15

    Highlights: • Solving the exhaust problem is crucial for DEMO. • Here, we discuss the new impurity radiation model in the systems code PROCESS. • Furthermore, we assess its effect on DEMO design. • More appropriate scalings will significantly enhance predictions for DEMO. • The controllability of highly radiative scenarios remains to be shown. - Abstract: For fusion reactors with ITER divertor technology, it will be imperative to significantly reduce the heat flux into the divertor e.g. by seeded impurity radiation. This has to be done without affecting the accessibility of a high performance scenario. To assess the implications of seeded plasma impurities on DEMO design, we have developed an impurity radiation model for radiation inside the separatrix. Evaluating the validity of our model, we find the assumption of a local ionisation equilibrium to be appropriate for our purposes and the assumption of flat impurity profiles – even though not satisfactory – to represent the best currently possible. Benchmarking our model against other codes highlights the need to use up to date atomic loss function data. From the impurity radiation perspective, the main uncertainties in current DEMO design stem from the lack of confinement and L-H-threshold scalings that can be robustly extrapolated to highly radiative DEMO scenarios as well as the lack of appropriate models for the power flow from the separatrix into the divertor that include radiation in the scrape off layer. Despite these uncertainties in the model we can exclude that significant fuel dilution through seeded impurities (with Z ≥ Z{sub Ar}) will be an issue for DEMO, but the controllability of highly radiative scenarios still needs to be coherently shown.

  20. Impurity transport in trapped electron mode driven turbulence

    CERN Document Server

    Mollén, A; Moradi, S; Fülöp, T

    2013-01-01

    Collisionless trapped electron mode turbulence is studied by gyrokinetic simulations with the GYRO code. Its impact on radial transport of high-Z trace impurities close to the core is thoroughly investigated, including the situation when a poloidally varying equilibrium electrostatic potential is present, and the dependence of the zero-flux impurity density gradient (peaking factor) on local plasma parameters is presented. Parameters such as ion-to-electron temperature ratio, electron temperature gradient and main species density gradient mainly affect the impurity peaking through their impact on mode characteristics. The poloidal asymmetry, the safety factor and magnetic shear have the strongest effect on impurity peaking, and it is shown that under certain scenarios where trapped electron modes are dominant, core accumulation of high-Z impurities can be avoided.

  1. Interplay of light and heavy impurities in a fusion device

    Science.gov (United States)

    Gaja, M.; Tokar, M. Z.

    2017-02-01

    ‘Breathing’ activity observed in the Large Helical Device stellarator is characterized by macro-scale oscillations of diverse plasma parameters such as the radiation losses from heavy (iron) and light (carbon and oxygen) impurities, electron density, temperature and the power absorbed in the plasma from neutral beam. They provide an example of a complex behavior in fusion plasmas triggered by the synergy effects from impurities of different species. A one-dimensional non-stationary model, describing the transport across flux surfaces in the plasma of the main and impurity neutral and charged particles, as well as of the thermal energy with the heat absorption from the neutral beam, radiation of high-Z ions from the plasma core and of low-Z impurities from the edge, is elaborated. The model is numerically realized, by applying the finite volume and ‘progonga’ methods to integrate the system of non-linearly coupled transport equations. The results of simulations presented reproduce qualitatively and essentially quantitatively the observations. The model allows prediction of the plasma and impurity environment conditions under which one has to expect ‘breathing’ oscillations.

  2. Local measurement of transport parameters for laser injected trace impurities

    Energy Technology Data Exchange (ETDEWEB)

    Giannella, R.; Lauro-Taroni, L. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking

    1994-07-01

    A procedure has been developed that determines local measurements of transport parameters`s profiles for injected impurities. The measured profiles extend from the plasma centre up to a certain radial position (usually {rho} = 0.6-0.7). In the outer region of the plasma the procedure supplies ``most suitable extensions`` up to the plasma edge of the measured transport profiles. The procedure intrinsically assures consistency and excellent agreement between the simulated and experimental data of local broad band soft X-ray emissivity and intensities of individual emission lines from different ion states of the injected impurities. 4 refs., 3 figs.

  3. Parallel impurity dynamics in the TJ-II stellarator

    CERN Document Server

    Alonso, J A; Estrada, T; Fontdecaba, J M; García-Regaña, J M; Geiger, J; Landreman, M; McCarthy, K J; Medina, F; Van Milligen, B Ph; Ochando, M A; Parra, F I; Velasco, J L

    2016-01-01

    We review in a tutorial fashion some of the causes of impurity density variations along field lines and radial impurity transport in the moment approach framework. An explicit and compact form of the parallel inertia force valid for arbitrary toroidal geometry and magnetic coordinates is derived and shown to be non-negligible for typical TJ-II plasma conditions. In the second part of the article, we apply the fluid model including main ion-impurity friction and inertia to observations of asymmetric emissivity patterns in neutral beam heated plasmas of the TJ-II stellarator. The model is able to explain qualitatively several features of the radiation asymmetry, both in stationary and transient conditions, based on the calculated in-surface variations of the impurity density.

  4. Parallel impurity dynamics in the TJ-II stellarator

    Science.gov (United States)

    Alonso, J. A.; Velasco, J. L.; Calvo, I.; Estrada, T.; Fontdecaba, J. M.; García-Regaña, J. M.; Geiger, J.; Landreman, M.; McCarthy, K. J.; Medina, F.; Van Milligen, B. Ph; Ochando, M. A.; Parra, F. I.; the TJ-II Team; the W7-X Team

    2016-07-01

    We review in a tutorial fashion some of the causes of impurity density variations along field lines and radial impurity transport in the moment approach framework. An explicit and compact form of the parallel inertia force valid for arbitrary toroidal geometry and magnetic coordinates is derived and shown to be non-negligible for typical TJ-II plasma conditions. In the second part of the article, we apply the fluid model including main ion-impurity friction and inertia to observations of asymmetric emissivity patterns in neutral beam heated plasmas of the TJ-II stellarator. The model is able to explain qualitatively several features of the radiation asymmetry, both in stationary and transient conditions, based on the calculated in-surface variations of the impurity density.

  5. Impurity solitons with quadratic nonlinearities

    DEFF Research Database (Denmark)

    Clausen, Carl A. Balslev; Torres, Juan P-; Torner, Lluis

    1998-01-01

    We fmd families of solitary waves mediated by parametric mixing in quadratic nonlinear media that are localized at point-defect impurities. Solitons localized at attractive impurities are found to be dynamically stable. It is shown that localization at the impurity modifies strongly the soliton p...

  6. Numerical calculation of impurity charge state distributions

    Energy Technology Data Exchange (ETDEWEB)

    Crume, E. C.; Arnurius, D. E.

    1977-09-01

    The numerical calculation of impurity charge state distributions using the computer program IMPDYN is discussed. The time-dependent corona atomic physics model used in the calculations is reviewed, and general and specific treatments of electron impact ionization and recombination are referenced. The complete program and two examples relating to tokamak plasmas are given on a microfiche so that a user may verify that his version of the program is working properly. In the discussion of the examples, the corona steady-state approximation is shown to have significant defects when the plasma environment, particularly the electron temperature, is changing rapidly.

  7. THE IMPURITY OF SCIENCE

    Energy Technology Data Exchange (ETDEWEB)

    Calvin, Melvin

    1962-04-19

    Science is impure in two ways. There is not a 'pure' science. By this I mean that physics impinges on astronomy, on the one hand, and chemistry on biology on the other. And not only does each support its neighbors but derives sustenance from them. The same can be said of chemistry. Biology is, perhaps, the example par excellence today of an 'impure' science. Beyond this, there is no 'pure' science itself divorced from human values. The importance of science to the humanities and the humanities to science in their complementary contribution to the variety of human life grows daily. The need for men familiar with both is imperative. We are faced today with a social decision resulting from our progress in molecular genetics at least equal to, and probably greater than, that required of us twenty years ago with the maturity of nuclear power.

  8. Measurement of the central ion and electron temperature of tokamak plasmas from the x-ray line radiation of high-Z impurity ions

    Energy Technology Data Exchange (ETDEWEB)

    Bitter, M.; von Goeler, S.; Goldman, M.; Hill, K.W.; Horton, R.; Roney, W.; Sauthoff, N.; Stodiek, W.

    1982-04-01

    This paper describes measurements of the central ion and electron temperature of tokamak plasmas from the observation of the 1s - 2p resonance lines, and the associated dielectronic (1s/sup 2/nl - 1s2pnl, with n greater than or equal to 2) satellites, of helium-like iron (Fe XXV) and titanium (Ti XXI). The satellite to resonance line ratios are very sensitive to the electron temperature and are used as an electron temperature diagnostic. The ion temperature is deduced from the Doppler width of the 1s - 2p resonance lines. The measurements have been performed with high resolution Bragg crystal spectrometers on the PLT (Princeton Large Torus) and PDX (Poloidal Divertor Experiment) tokamaks. The details of the experimental arrangement and line evaluation are described, and the ion and electron temperature results are compared with those obtained from independent diagnostic techniques, such as the analysis of charge-exchange neutrals and measurements of the electron cyclotron radiation. The obtained experimental results permit a detailed comparison with theoretical predictions.

  9. Parallel Impurity Spreading During Massive Gas Injection

    Science.gov (United States)

    Izzo, V. A.

    2016-10-01

    Extended-MHD simulations of disruption mitigation in DIII-D demonstrate that both pre-existing islands (locked-modes) and plasma rotation can significantly influence toroidal spreading of impurities following massive gas injection (MGI). Given the importance of successful disruption mitigation in ITER and the large disparity in device parameters, empirical demonstrations of disruption mitigation strategies in present tokamaks are insufficient to inspire unreserved confidence for ITER. Here, MHD simulations elucidate how impurities injected as a localized jet spread toroidally and poloidally. Simulations with large pre-existing islands at the q = 2 surface reveal that the magnetic topology strongly influences the rate of impurity spreading parallel to the field lines. Parallel spreading is largely driven by rapid parallel heat conduction, and is much faster at low order rational surfaces, where a short parallel connection length leads to faster thermal equilibration. Consequently, the presence of large islands, which alter the connection length, can slow impurity transport; but the simulations also show that the appearance of a 4/2 harmonic of the 2/1 mode, which breaks up the large islands, can increase the rate of spreading. This effect is seen both for simulations with spontaneously growing and directly imposed 4/2 modes. Given the prevalence of locked-modes as a cause of disruptions, understanding the effect of large islands is of particular importance. Simulations with and without islands also show that rotation can alter impurity spreading, even reversing the predominant direction of spreading, which is toward the high-field-side in the absence of rotation. Given expected differences in rotation for ITER vs. DIII-D, rotation effects are another important consideration when extrapolating experimental results. Work supported by US DOE under DE-FG02-95ER54309.

  10. Wall Conditioning and Impurity Measurements in the PEGASUS Experiment

    Science.gov (United States)

    Ono, M.; Fonck, R.; Toonen, R.; Thorson, T.; Tritz, K.; Winz, G.

    1999-11-01

    Wall conditioning and impurity effects on plasma evolution are increasingly relevant to the PEGASUS program. Surface conditioning consists of hydrogen glow discharge cleaning (GDC) to remove water and oxides, followed by He GDC to reduce the hydrogen inventory. Isotope exchange measurements indicate that periodic He GDC almost eliminates uncontrolled fueling from gas desorbed from the limiting surfaces. Additional wall conditioning will include Ti gettering and/or boronization. Impurity monitoring is provided by the recent installation of a SPRED multichannel VUV spectrometer (wavelength range = 10-110 nm; 1 msec time resolution), several interference filter (IF) monochromators, and a multichannel Ross-filter SXR diode assembly (for CV, CVI, OVII, and OVIII). The IF monitors indicate increased C radiation upon contact of the plasma with the upper and lower limiters for highly elongated plasmas. This radiation appears correlated with a subsequent rollover in the plasma current, and motivates an upgrade to the poloidal limiters to provide better plasma-wall interaction control.

  11. Disruption mitigation using laser ablation of high-Z impurities in HL-1M tokamak

    Institute of Scientific and Technical Information of China (English)

    Zheng Yong-Zhen; Feng Xing-Ya; Guo Gan-Cheng; Xu De-Ming; Zheng Yin-Jia

    2006-01-01

    A preliminary experiment triggering a plasma current quench by laser ablation of high-Z impurities has been performed in the HL-1M tokamak. The injection of impurities with higher electric charges into tokamak plasmas can increase the radiation cooling of the plasma. Resistive, highly radiating plasma formed prior to the thermal quench can dissipate both the thermal and magnetic energies, which is possibly a simple and potential approach to reducing significantly the plasma thermal energy and magnetic energy before a disruption thereby a safe plasma termination is obtained.

  12. Power balance and characterization of impurities in the Maryland Spheromak

    Energy Technology Data Exchange (ETDEWEB)

    Cote, C.

    1993-12-31

    The Maryland Spheromak is a medium size magnetically confined plasma of toroidal shape. Low T{sub e} and higher n{sub e} than expected contribute to produce a radiation dominated short-lived spheromak configuration. A pyroelectric radiation detector and a VUV spectrometer have been used for space and time-resolved measurements of radiated power and impurity line emission. Results from the bolometry and VUV spectroscopy diagnostics have been combined to give the absolute concentrations of the major impurity species together with the electron temperature. The large amount of oxygen and nitrogen ions in the plasma very early in the discharge is seen to be directly responsible for the abnormally high electron density. The dominant power loss mechanisms are found to be radiation (from impurity line emission) and electron convection to the end walls during the formation phase of the spheromak configuration, and radiation only during the decay phase.

  13. Radiative Loss For Carbon Plasma Impurity

    Institute of Scientific and Technical Information of China (English)

    1994-01-01

    3.27RadiativeLossForCarbonPlasmaImpurityYaoJinzhangWehavecalculatedtheradiativelossforcarbonintheimpurityplasmabyamodifiedcor...

  14. Spectroscopic Measurements of Impurity Spectra on the EAST Tokamak

    Institute of Scientific and Technical Information of China (English)

    FU Jia; LI Yingying; SHI Yuejiang; WANG Fudi; ZHANG Wei; LV Bo; HUANG Juan; WAN Baonian; ZHOU Qian

    2012-01-01

    Ultraviolet (UV) and visible impurity spectra (200-750 nm) are commonly used to study plasma and wall interactions in magnetic fusion plasmas. Two optical multi-channel analysis (OMA) systems have been installed for the UV-visible spectrum measurement on EAST. These two OMA systems are both equipped with the Czerny-Turner (C-T) type spectrometer. The upper vacuum vessel and inner divertor baffle can be viewed simultaneously through two optical lenses. The OMA1 system is mainly used for multi-impurity lines radiation measurement. A 280 nm wavelength range can be covered by a 300 mm focal length spectrometer equipped with a 300 grooves/mm grating. The Da/Ha line shapes can be resolved by the OMA2 system. The focal length is 750 mm. The spectral resolution can be up to 0.01 nm using a 1800 grooves/mm grating. The impurity behaviour and hydrogen ratio evolution after boroniztion, lithium coating, and siliconization are compared. Lithium coating has shown beneficial effects on the reduction of edge recycling and low Z impurity (C, O) influx. The impurity expelling effect of the divertor configuration is also briefly discussed through multi-channels observation of OMA1 system.

  15. Isotopic dependence of impurity transport driven by ion temperature gradient turbulence

    CERN Document Server

    Guo, Weixin; Zhuang, Ge

    2016-01-01

    Hydrogenic ion mass effects, namely the isotopic effects on impurity transport driven by ion temperature gradient (ITG) turbulence are investigated using gyrokinetic theory. For non-trace impurities, changing from hydrogen (H) to deuterium (D), and to tritium (T) plasmas, the outward flux for lower (higher) ionized impurities or for lighter (heavier) impurities is found to decrease (increase), although isotopic dependence of ITG linear growth rate is weak. This is mainly due to the decrease of outward (inward) convection, while the isotopic dependence of diffusion is relatively weak. In addition, the isotopic effects reduce (enhance) the impurity flux of fully ionized carbon (C6+) for weaker (stronger) magnetic shear. In trace impurity limit, the isotopic effects are found to reduce the accumulation of high-Z tungsten (W). Moreover, the isotopic effects on the peaking factor (PF) of trace high-Z W get stronger with stronger magnetic shear.

  16. Impurities in Silicon Nanocrystals: The intentional and the inherent

    Science.gov (United States)

    Rowe, David J.

    Silicon nanocrystals (SiNCs) have become an important class of materials in the fields of photovoltaics, thermoelectrics, lighting, and medicine. Impurities within SiNCs dramatically alter the electrical and optical properties of the host material, whether the impurity is intentionally added in an attempt to manipulate properties, or is inherent to the material and its natural state. Despite such remarkable changes, impurity incorporation within SiNCs remains poorly understood, since concepts applied to understanding impurities in bulk materials may not completely translate to nanomaterials. Understanding the effect of SiNC impurities requires new technologies to produce materials suitable for study combined with new insights to expound the differences in the nanoscale physics. Nonthermal plasma-assisted gas-phase synthesis provides an excellent route to producing and investigating impurities within SiNCs due to the unique chemical reaction environment of the plasma. The robustness of such a technique allows for the production of very pure SiNCs or SiNCs with added impurities simply by adding different chemicals to the plasma. The chapters in this document focus on the effect that different impurities have on the properties of SiNCs. Chapter 2 focuses on heavily P-doped SiNCs exhibiting the first known observation of a unique electrical and optical property known as localized surface plasmon resonance (LSPR) within free-standing SiNCs. Chapter 3 explains the synthesis of B- and P-doped SiGeNC alloys and their deposition into thin films for thermoelectric applications. Chapter 4 highlights research which uses P-doped SiNCs to form emitter layers for pn-junction type solar cells, including device fabrication and optical characterization. Chapter 5 examines inherent impurities in the form of dangling bond defects which may be responsible for the quenching of SiNC photoluminescence, and their evolution during the process of air-ambient oxidation. Several appendices at

  17. Impurity Influence on Nitride LEDs

    Directory of Open Access Journals (Sweden)

    O.I. Rabinovich

    2014-07-01

    Full Text Available Light emitting diodes (LEDs are widely used nowadays. They are used in major parts of our life. But it is still necessary to improve their characteristics. In this paper the impurity and Indium atoms influence on the LEDs characteristics is investigated by computer simulation. Simulation was carried out in Sim Windows. The program was improved for this purpose by creating new files for AlGaInN heterostructure and devices including more than 25 basic parameters. It was found that characteristics depend on impurity and indium atoms changes a lot. The optimum impurity concentration for doping barriers between quantum wells was achieved. By varying impurity and Indium concentration the distribution in AlGaInN heterostructure LEDs characteristics could be improved.

  18. Mitigation of the tracer impurity accumulation by EC heating in the LHD

    Science.gov (United States)

    Tamura, N.; Sudo, S.; Suzuki, C.; Funaba, H.; Nakamura, Y.; Tanaka, K.; Yoshinuma, M.; Ida, K.; The LHD Experiment Group

    2016-11-01

    The mitigation of a tracer impurity accumulation in the core region of high-temperature helical plasma was clearly observed by applying electron cyclotron heating (ECH) in the large helical device (LHD). In the LHD, the accumulation of impurities toward the centre of the plasma has been observed in a high-density regime. In this study, for observing clearly the behaviour of impurity ions in the plasma core, the extrinsic ‘tracer’ impurity was injected into that region by means of a tracer-encapsulated solid pellet (TESPEL). The high-density LHD plasma without ECH definitely shows the strong impurity accumulation, and then it causes the reduction in electron and ion temperatures in the core region. When ECH was applied just after the TESPEL injection, the accumulation of the tracer impurity ions was mitigated. Even after ECH was switched-off, the intensities of the line emissions from the highly-ionized tracer impurity were increased very slightly. The micro-turbulence measurement with a 2-dimensional phase contrast imaging diagnostic during ECH does not support the view that the change in the micro-turbulence would enhance the outward flow (an increase in a diffusive flux, a decrease in an inward convective flux and/or a change the direction of the convective flux from inward to outward) of the impurity ions. Moreover, at this moment, there is no conclusive data regarding a radial electric field measured with a charge exchange spectroscopy diagnostic to support the view that the change in the radial electric field would be attributed to the increment in the outward flow of the impurity ions from the core region of the LHD plasma.

  19. Global effects on neoclassical transport in the pedestal with impurities

    CERN Document Server

    Pusztai, I; Landreman, M

    2016-01-01

    We present a numerical study of collisional transport in a tokamak pedestal in the presence of non-trace impurities, using the radially global $\\delta f$ neoclassical solver PERFECT [M. Landreman et al. 2014 Plasma Phys. Control. Fusion 56 045005]. It is known that in a tokamak core with non-trace impurities present the radial impurity flux opposes the bulk ion flux to provide an ambipolar particle transport, with the electron transport being negligibly small. However, in a sharp density pedestal with sub-sonic ion flows the electron transport can be comparable to the ion and impurity flows. Furthermore, the neoclassical particle transport is not intrinsically ambipolar, and the non-ambipolarity of the fluxes extends outside the pedestal region by the radial coupling of the perturbations. The neoclassical momentum transport, which is finite in the presence of ion orbit-width scale profile variations, is significantly enhanced when impurities are present in non-trace quantities, even if the total parallel mass...

  20. Radiated Power and Impurity Concentrations in the EXTRAP-T2R Reversed-Field Pinch

    Science.gov (United States)

    Corre, Y.; Rachlew, E.; Cecconello, M.; Gravestijn, R. M.; Hedqvist, A.; Pégourié, B.; Schunke, B.; Stancalie, V.

    2005-01-01

    A numerical and experimental study of the impurity concentration and radiation in the EXTRAP-T2R device is reported. The experimental setup consists of an 8-chord bolometer system providing the plasma radiated power and a vacuum-ultraviolet spectrometer providing information on the plasma impurity content. The plasma emissivity profile as measured by the bolometric system is peaked in the plasma centre. A one dimensional Onion Skin Collisional-Radiative model (OSCR) has been developed to compute the density and radiation distributions of the main impurities. The observed centrally peaked emissivity profile can be reproduced by OSCR simulations only if finite particle confinement time and charge-exchange processes between plasma impurities and neutral hydrogen are taken into account. The neutral hydrogen density profile is computed with a recycling code. Simulations show that recycling on metal first wall such as in EXTRAP-T2R (stainless steel vacuum vessel and molybdenum limiters) is compatible with a rather high neutral hydrogen density in the plasma centre. Assuming an impurity concentration of 10% for oxygen and 3% for carbon compared with the electron density, the OSCR calculation including lines and continuum emission reproduces about 60% of the total radiated power with a similarly centrally peaked emissivity profile. The centrally peaked emissivity profile is due to low ionisation stages and strongly radiating species in the plasma core, mainly O4+ (Be-like) and C3+ Li-like.

  1. Observation of the ECH effect on the impurity accumulation in the LHD

    Science.gov (United States)

    Tamura, N.; Suzuki, C.; Satake, S.; Nakamura, Y.; Nunami, M.; Funaba, H.; Tanaka, K.; Yoshinuma, M.; Ida, K.; Sudo, S.

    2017-05-01

    Recent experiments in the Large Helical Device (LHD) clearly show the ability of electron cyclotron heating (ECH) to control accumulation of impurities, as demonstrated by external injection of a tracer-encapsulated solid pellet (TESPEL). The impurity introduced locally into the core region of the LHD plasma by the TESPEL has strongly accumulated in a high-density LHD plasma, as well as an intrinsic impurity, such as a carbon. When a high-power (1.5 MW) ECH is applied just after the TESPEL injection for such a plasma, the accumulation of the impurity injected by the TESPEL was almost completely suppressed. This result indicates that applying ECH enhances the outward radial impurity flux. Although a neoclassical ambipolar radial electric field in stellarators has a stronger impact on the transport, particularly on the impurity transport, than in tokamaks, the sign of the radial electric field measured and calculated is directed to a negative even in the 1.5 MW ECH case, resulting in the inward impurity flux. By revisiting the neoclassical formulation, an increment of ion temperature and its gradient could be one of the candidates for the explanation, since the ion temperature is also increased globally by ECH.

  2. Impurity bubbles in a BEC

    Science.gov (United States)

    Timmermans, Eddy; Blinova, Alina; Boshier, Malcolm

    2013-05-01

    Polarons (particles that interact with the self-consistent deformation of the host medium that contains them) self-localize when strongly coupled. Dilute Bose-Einstein condensates (BECs) doped with neutral distinguishable atoms (impurities) and armed with a Feshbach-tuned impurity-boson interaction provide a unique laboratory to study self-localized polarons. In nature, self-localized polarons come in two flavors that exhibit qualitatively different behavior: In lattice systems, the deformation is slight and the particle is accompanied by a cloud of collective excitations as in the case of the Landau-Pekar polarons of electrons in a dielectric lattice. In natural fluids and gases, the strongly coupled particle radically alters the medium, e.g. by expelling the host medium as in the case of the electron bubbles in superfluid helium. We show that BEC-impurities can self-localize in a bubble, as well as in a Landau-Pekar polaron state. The BEC-impurity system is fully characterized by only two dimensionless coupling constants. In the corresponding phase diagram the bubble and Landau-Pekar polaron limits correspond to large islands separated by a cross-over region. The same BEC-impurity species can be adiabatically Feshbach steered from the Landau-Pekar to the bubble regime. This work was funded by the Los Alamos LDRD program.

  3. Impurity effects on toroidal ITG-modes and transport in tokamaks

    Energy Technology Data Exchange (ETDEWEB)

    Froejdh, M.

    1993-04-01

    The presence of impurities in tokamak plasmas has until recently been ignored in several fluctuation driven transport models. In this thesis some of the consequences of including an ion impurity species into a model for low frequency electrostatic modes and fluctuation driven transport are discussed. The direction of the particle flows in a two-ion-component plasma is studied for the outer part of the good confinement region. When the two ion species, main and impurity ions, have similar inwardly peaked density profiles the latter tends to determine the flow directions for typical tokamak plasma conditions. Hence, the impurities flow outwards and the main ions inwards, leading to so called plasma decontamination. The stability of the toroidal main and impurity ion temperature gradient modes (ITG-modes) is determined by using an advanced fluid model. The impurity effect on the background mode is found to be stabilizing for a large domain of parameters. However, a destabilization is also possible. An impurity mode driven by toroidicity is found and shown to be unstable in a new parameter region. The particle and thermal diffusivities are estimated and the scaling properties are studied. The magnitude of the ion thermal conductivity is shown to decrease due to the stabilizing influence of impurities. The radial variation of the transport coefficients are considered for some experimental equilibrium profiles. The stability properties of a contaminated tokamak plasma with dissipative trapped electrons are investigated. The dissipation is found to change the instability thresholds. The relation between wave energy, electron dissipation and instability is discussed. (35 refs.).

  4. Wall power measurements of impurity radiation in ORMAK

    Energy Technology Data Exchange (ETDEWEB)

    Bush, C.E.; Lyon, J.F.

    1977-12-01

    Time- and space-resolved measurements of the power loss to the liner of the Oak Ridge Tokamak (ORMAK) indicate that a large fraction (approx.60%) of the electron power input is lost to the wall, rather than to the limiter. This fraction is relatively constant over a wide range of input powers (ohmic heating plus neutral beam injection) and plasma conditions and for most of the discharge duration. Most of this energy loss is due to impurity radiation from an emission profile having a mean radius about a third that of the limiter radius and is time-correlated with gross plasma fluctuations, internal disruptions, and related spectroscopic impurity signals. In gas puffing experiments resulting in higher densities, the ratio of radiative power to the electron density continually falls as density increases during the course of the discharge.

  5. Impurity doping processes in silicon

    CERN Document Server

    Wang, FFY

    1981-01-01

    This book introduces to non-experts several important processes of impurity doping in silicon and goes on to discuss the methods of determination of the concentration of dopants in silicon. The conventional method used is the discussion process, but, since it has been sufficiently covered in many texts, this work describes the double-diffusion method.

  6. Breatherlike impurity modes in discrete nonlinear lattices

    DEFF Research Database (Denmark)

    Hennig, D.; Rasmussen, Kim; Tsironis, G. P.

    1995-01-01

    We investigate the properties of a disordered generalized discrete nonlinear Schrodinger equation, containing both diagonal and nondiagonal nonlinear terms. The equation models a Linear host lattice doped with nonlinear impurities. We find different types of impurity states that form itinerant...

  7. Observation and Calculation of the ECRH Effect on the Tracer Impurity Accumulation in LHD

    Science.gov (United States)

    Tamura, Naoki

    2016-10-01

    In a magnetic confinement fusion reactor various Z impurities will exist inside the plasma. When the amount of the impurities exceeds the acceptable level by an accumulation, this will lead to impermissible plasma performance degradation due to the radiation losses and plasma dilution. Therefore, it is crucially important to develop effective schemes for controlling the impurities in the core plasma and to understand the underlying physical mechanisms of such schemes. Recent LHD experiments show the ability of ECRH to control the impurity accumulation. Experiments on the LHD have used a tracer-encapsulated solid pellet (TESPEL), which is embedded with vanadium, to introduce the extrinsic and non-recycling impurity directly inside the last-closed flux surface (LCFS) region. Therefore, the confinement time of the vanadium impurity can be directly evaluated from the time history of highly ionized vanadium ion. In cases where the collisionality between the impurity ions and the bulk ion is in the Banana-Plateau regime (but close to the collisional Pfirsch-Schlüter (PS) regime), the impurities in the LHD plasma are strongly accumulated into the core plasma. When the 1.5 MW 154 GHz ECRH is applied for such plasma just after the TESPEL injection, the accumulation of the vanadium ions was almost completely suppressed. This result indicates that applying ECRH changes the direction of the radial vanadium particle flux from the inward to the outward. Although the neoclassical ambipolar radial electric field in stellarators has a stronger impact on the transport, particularly on the impurity transport, than in tokamaks, there is no conclusive data regarding a radial electric field measured with a charge exchange spectroscopy diagnostic to support the view that the change in the radial electric field would be attributed to the outward flow of the vanadium ions in the LHD plasma. In this contribution, the results of ongoing evaluations of the neoclassical (e.g., PENTA/DKES that

  8. Fundamental aspects of metallic impurities and impurity interactions in silicon during device processing

    Energy Technology Data Exchange (ETDEWEB)

    Graff, K. [TEMIC, TELEFUNKEN, Heilbronn (Germany)

    1995-08-01

    A review on the behavior of metallic impurities in silicon can be considerably simplified by a restriction on pure, dislocation-free, monocrystalline silicon. In this case interactions between different impurities and between impurities and grown-in lattice defects can be reduced. This restriction is observed in Chapter 1 for discussing the general behavior of metallic impurities in silicon.

  9. Impurity transport of high performance discharges in JET

    Energy Technology Data Exchange (ETDEWEB)

    Lauro-Taroni, L.; Alper, B.; Giannella, R.; Marcus, F.; Smeulders, P.; Von Hellermann, M. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Lawson, K. [UKAEA Culham Lab., Abingdon (United Kingdom); Mattioli, M. [Association Euratom-CEA, Centre d`Etudes Nucleaires de Cadarache, 13 - Saint-Paul-lez-Durance (France). Dept. de Recherches sur la Fusion Controlee

    1994-07-01

    Experimental data show that in the Pellet Enhanced Performance (PEP) H-mode discharges, the light impurities are dominant and accumulate. Furthermore, strong fuel depletion may occur in the plasma centre with n{sub D}/n{sub e} falling to about 0.3 in some cases. On the other hand, in Hot-Ion discharges hollow profiles are measured for C: it is present in lower concentrations and has little effect on fuel dilution. The different behaviour of carbon in the two cases is in agreement with neoclassical predictions for the convection in the plasma core. 6 refs., 6 figs.

  10. Numerical Analysis of Impurity Transport along Magnetic Field Lines in Tokamak Scrape-Off Layer

    Science.gov (United States)

    Chung, Tae Kyun; Hong, Sang Hee

    1996-11-01

    A flow of impurity ions along the magnetic field lines in tokamak SOL (scrape-off layer) is investigated by a one-dimensional numerical analysis. The background values of SOL plasma, fields such as density, velocity, temperature and electric field, are obtained from an edge plasma transport code EDGETRAN(A 2-D edge plasma transport code with limited and diverted tokamak configurations developed by Dr. Kihak Im at Seoul National University). Impurity ions are generated by ionizations of neutral atoms in tokamak. The density profile of neutral atoms is given at an initial state. Impurity ions in a single-charged state develop into multi-charged states by ionization and recombination reactions. Impurity productions at the divertor target plate by sputterings are also considered as main source terms. As a numerics, FDM(Finite Difference Method) is employed. The Neumann condition on impurity density and the Dirchlet condition on impurity velocity are provided for their boundary conditions at a symmetry plane of the layer. No strict boundary condition on the target plate is given except an external source prescribed by sputtering rates.

  11. Determination of impurity element aluminum in spirulina by inductively coupled plasma atomic emission spectrometry%ICP-AES法测定螺旋藻中的杂质元素铝

    Institute of Scientific and Technical Information of China (English)

    林易晨

    2015-01-01

    探讨用ICP-AES技术测定螺旋藻中杂质元素铝,并对共存元素光谱干扰及其消除进行研究,所建立的分析方法,快速、结果准确,有较好的精密度和准确度,适用于螺旋藻中铝的测定.%The determination of impurity element aluminum in spirulina by ICP-AES was studied. The spectral interference and elimination of coexisting elements was investigated. The established analytical method is fast ,precise and accurate. The method is applicable to the determination of aluminum content in spirulina.

  12. Method to obtain absolute impurity density profiles combining charge exchange and beam emission spectroscopy without absolute intensity calibrationa)

    Science.gov (United States)

    Kappatou, A.; Jaspers, R. J. E.; Delabie, E.; Marchuk, O.; Biel, W.; Jakobs, M. A.

    2012-10-01

    Investigation of impurity transport properties in tokamak plasmas is essential and a diagnostic that can provide information on the impurity content is required. Combining charge exchange recombination spectroscopy (CXRS) and beam emission spectroscopy (BES), absolute radial profiles of impurity densities can be obtained from the CXRS and BES intensities, electron density and CXRS and BES emission rates, without requiring any absolute calibration of the spectra. The technique is demonstrated here with absolute impurity density radial profiles obtained in TEXTOR plasmas, using a high efficiency charge exchange spectrometer with high etendue, that measures the CXRS and BES spectra along the same lines-of-sight, offering an additional advantage for the determination of absolute impurity densities.

  13. Method to obtain absolute impurity density profiles combining charge exchange and beam emission spectroscopy without absolute intensity calibration

    Energy Technology Data Exchange (ETDEWEB)

    Kappatou, A.; Delabie, E. [FOM Institute DIFFER - Dutch Institute for Fundamental Energy Research, Association EURATOM-FOM, 3430 BE Nieuwegein (Netherlands); Jaspers, R. J. E.; Jakobs, M. A. [Science and Technology of Nuclear Fusion, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Marchuk, O.; Biel, W. [Institute for Energy and Climate Research, Forschungszentrum Julich GmbH, Trilateral Euregio Cluster, 52425 Julich (Germany)

    2012-10-15

    Investigation of impurity transport properties in tokamak plasmas is essential and a diagnostic that can provide information on the impurity content is required. Combining charge exchange recombination spectroscopy (CXRS) and beam emission spectroscopy (BES), absolute radial profiles of impurity densities can be obtained from the CXRS and BES intensities, electron density and CXRS and BES emission rates, without requiring any absolute calibration of the spectra. The technique is demonstrated here with absolute impurity density radial profiles obtained in TEXTOR plasmas, using a high efficiency charge exchange spectrometer with high etendue, that measures the CXRS and BES spectra along the same lines-of-sight, offering an additional advantage for the determination of absolute impurity densities.

  14. Long-term evolution of the impurity composition and impurity events with the ITER-like wall at JET

    Science.gov (United States)

    Coenen, J. W.; Sertoli, M.; Brezinsek, S.; Coffey, I.; Dux, R.; Giroud, C.; Groth, M.; Huber, A.; Ivanova, D.; Krieger, K.; Lawson, K.; Marsen, S.; Meigs, A.; Neu, R.; Puetterich, T.; van Rooij, G. J.; Stamp, M. F.; Contributors, JET-EFDA

    2013-07-01

    This paper covers aspects of long-term evolution of intrinsic impurities in the JET tokamak with respect to the newly installed ITER-like wall (ILW). At first the changes related to the change over from the JET-C to the JET-ILW with beryllium (Be) as the main wall material and tungsten (W) in the divertor are discussed. The evolution of impurity fluxes in the newly installed W divertor with respect to studying material migration is described. In addition, a statistical analysis of transient impurity events causing significant plasma contamination and radiation losses is shown. The main findings comprise a drop in carbon content (×20) (see also Brezinsek et al (2013 J. Nucl. Mater. 438 S303)), low oxygen content (×10) due to the Be first wall (Douai et al 2013 J. Nucl. Mater. 438 S1172-6) as well as the evolution of the material mix in the divertor. Initially, a short period of repetitive ohmic plasmas was carried out to study material migration (Krieger et al 2013 J. Nucl. Mater. 438 S262). After the initial 1600 plasma seconds the material surface composition is, however, still evolving. With operational time, the levels of recycled C are increasing slightly by 20% while the Be levels in the deposition-dominated inner divertor are dropping, hinting at changes in the surface layer material mix made of Be, C and W. A steady number of transient impurity events, consisting of W and constituents of inconel, is observed despite the increase in variation in machine operation and changes in magnetic configuration as well as the auxiliary power increase.

  15. Colloidal Plasmas : Basic physics of colloidal plasmas

    Indian Academy of Sciences (India)

    C B Dwivedi

    2000-11-01

    Colloidal plasma is a distinct class of the impure plasmas with multispecies ionic composition. The distinction lies in the phase distribution of the impurity-ion species. The ability to tailor the electrostatic interactions between these colloidal particles provides a fertile ground for scientists to investigate the fundamental aspects of the Coulomb phase transition behavior. The present contribution will review the basic physics of the charging mechanism of the colloidal particles as well as the physics of the collective normal mode behavior of the general multi-ion species plasmas. Emphasis will be laid on the clarification of the prevailing confusing ideas about distinct qualities of the various acoustic modes, which are likely to exist in colloidal plasmas as well as in normal multi-ion species plasmas. Introductory ideas about the proposed physical models for the Coulomb phase transition in colloidal plasma will also be discussed.

  16. Evolution of impurity incorporation during ammonothermal growth of GaN

    Science.gov (United States)

    Sintonen, Sakari; Wahl, Stefanie; Richter, Susanne; Meyer, Sylke; Suihkonen, Sami; Schulz, Tobias; Irmscher, Klaus; Danilewsky, Andreas N.; Tuomi, Turkka O.; Stankiewicz, Romuald; Albrecht, Martin

    2016-12-01

    Ammonothermally grown GaN is a promising substrate for high-power optoelectronics and electronics thanks to its scalability and high structural perfection. Despite extensive research, ammonothermal GaN still suffers from significant concentrations of impurities. This article discusses the evolution of impurity incorporation during growth of basic ammonothermal GaN, in specific whether the impurity concentration changes temporally along the growth direction and how the autoclave influences the impurity concentration. The effect of the impurities on the structural, electrical and optical properties of the grown crystal is also discussed. The chemical analysis is carried out by time of flight secondary ion mass spectroscopy (ToF-SIMS) and laser-ablation inductively-coupled plasma mass spectroscopy (LA-ICP-MS). Strain and dislocation generation caused by impurity concentration gradients and steps are studied by synchrotron radiation x-ray topography (SR-XRT). Fourier transform infrared (FTIR) reflectivity is used to determine the effect of the impurities on the free carrier concentration, and the luminescent properties are studied by low temperature photoluminescence (PL). The influence of the autoclave is studied by growing a single boule in multiple steps in several autoclaves. LA-ICP-MS and ToF-SIMS ion intensities indicate that the impurity concentrations of several species vary between different autoclaves by over an order of magnitude. SR-XRT measurements reveal strain at the growth interfaces due to impurity concentration gradients and steps. Oxygen is determined to be the most abundant impurity species, resulting in a high free carrier concentration, as determined by FTIR. The large variation in Mn concentration dramatically affects PL intensity.

  17. Development of wall conditioning and impurity monitoring systems in Versatile Experiment Spherical Torus (VEST)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H.Y., E-mail: brbbebbero@snu.ac.kr [Seoul National University, Seoul (Korea, Republic of); Yang, J.; Kim, Y.G.; Yang, S.M.; Kim, Y.S.; Lee, K.H. [Seoul National University, Seoul (Korea, Republic of); An, Y.H. [National Fusion Research Institute, Daejon (Korea, Republic of); Chung, K.J.; Na, Y.S. [Seoul National University, Seoul (Korea, Republic of); Hwang, Y.S., E-mail: yhwang@snu.ac.kr [Seoul National University, Seoul (Korea, Republic of)

    2016-11-01

    Highlights: • The baking for partial wall heating and H{sub 2}/He GDC systems are developed in VEST. • The RGA and OES systems for monitoring impurities are constructed in VEST. • The partial baking and He GDC show limited effects on plasma characteristics. • H{sub 2} GDC above 4 h enables the longer plasma current duration up to ∼15 ms. • After H{sub 2} GDC, the discharge should be conducted within 3 h from treatment. - Abstract: Wall conditioning and impurity monitoring systems are developed in Versatile Experiment Spherical Torus (VEST). As a wall conditioning system, a baking system covering the vacuum vessel wall partially and a glow discharge cleaning (GDC) system using two electrodes with dc and 50 kHz power supplies are installed. The GDC system operates with hydrogen and helium gases for both chemical and physical desorption. The impurity monitoring system with residual gas analyzer (RGA), operating at <10{sup −5} Torr with a differential pumping system, is installed along with the optical emission spectroscopy (OES) system to monitor the hydrogen and impurity radiation lines. Effects of these wall conditioning techniques are investigated with the impurity monitoring system for ohmic discharges of VEST. The partial baking and He GDC show limited effects on plasma characteristics but sufficient H{sub 2} GDC above 4 h enables the longer plasma current duration up to ∼15 ms within 3 h from the end of treatment.

  18. Impurities Removal in Seawater to Optimize the Magnesium Extraction

    Science.gov (United States)

    Natasha, N. C.; Firdiyono, F.; Sulistiyono, E.

    2017-02-01

    Magnesium extraction from seawater is promising way because magnesium is the second abundant element in seawater and Indonesia has the second longest coastline in the world. To optimize the magnesium extraction, the impurities in seawater need to be eliminated. Evaporation and dissolving process were used in this research to remove the impurities especially calcium in seawater. Seawater which has been evaporated from 100 ml to 50 ml was dissolved with variations solution such as oxalic acid and ammonium bicarbonate. The solution concentration is 100 g/l and it variations are 2 ml, 4 ml, 6 ml, 8 ml, 10 ml, 20 ml, 30 ml, 40 ml and 50 ml. This step will produce precipitate and filtrate then it will be analysed to find out the result of this process. The precipitate was analysed by X-ray Diffraction (XRD) and Scanning Electron Microscope (SEM) but the filtrate was analysed by Inductively Coupled Plasma (ICP). XRD analysis shows that calcium oxalate and calcium carbonate were formed and ICP analysis shows that the remaining calcium in seawater using oxalic acid is about 0.01% and sodium 0.14% but when using ammonium bicarbonate the remaining calcium is 2.5% and sodium still more than 90%. The results show that both oxalic acid and ammonium bicarbonate can remove the impurities but when using oxalic acid, not only the impurities but also magnesium was precipitated. The conclusion of this research is the best solution to remove the impurities in seawater without precipitate the magnesium is using ammonium bicarbonate.

  19. Plasma polarization spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fujimoto, Takashi [Department of Engineering Physics and Mechanics, Graduate School of Engineering, Kyoto University, Kyoto (Japan)

    2000-03-01

    Polarization of radiation emitted from a plasma reflects the anisotropic properties of the plasma, especially the angular anisotropic distribution of electron velocities. Polarization has been observed on impurity ion lines from the WT-3 tokamak and the GAMMA-10 tandem mirror machines. The soft x-ray laser line from the neonlike germanium was also found polarized. (author)

  20. Plasma polarization spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Iwamae, Atsushi; Inoue, Takeru; Tanaka, Akihiro; Kawakami, Kazuki; Fujimoto, Takashi [Kyoto Univ., Dept. of Engineering Physics, Kyoto (Japan)

    2000-03-01

    Polarization of radiation emitted from plasma reflects the anisotropic properties of the plasma, especially the angular isotropic distribution of electron velocities. Polarization has been observed on impurity ion lines from the WT-3 tokamak and GAMMA 10 tandem mirror device. (author)

  1. Classical confinement and outward convection of impurity ions in the MST RFP

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, S. T. A.; Den Hartog, D. J.; Mirnov, V. V.; Eilerman, S.; Nornberg, M.; Reusch, J. A.; Sarff, J. S. [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Caspary, K. J.; Chapman, B. E.; Parke, E. [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Magee, R. M. [Department of Physics, West Virginia University, Morgantown, WV 26506 (United States); Brower, D. L.; Ding, W. X.; Lin, L. [Department of Physics and Astronomy, University of California, Los Angeles, California 90095 (United States); Craig, D. [Physics Department, Wheaton College, Wheaton, Illinois 60187 (United States); Fiksel, G. [Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Laboratory for Laser Energetics, University of Rochester, Rochester, New York (United States)

    2012-05-15

    Impurity ion dynamics measured with simultaneously high spatial and temporal resolution reveal classical ion transport in the reversed-field pinch. The boron, carbon, oxygen, and aluminum impurity ion density profiles are obtained in the Madison Symmetric Torus [R. N. Dexter et al., Fusion Technol. 19, 131 (1991)] using a fast, active charge-exchange-recombination-spectroscopy diagnostic. Measurements are made during improved-confinement plasmas obtained using inductive control of tearing instability to mitigate stochastic transport. At the onset of the transition to improved confinement, the impurity ion density profile becomes hollow, with a slow decay in the core region concurrent with an increase in the outer region, implying an outward convection of impurities. Impurity transport from Coulomb collisions in the reversed-field pinch is classical for all collisionality regimes, and analysis shows that the observed hollow profile and outward convection can be explained by the classical temperature screening mechanism. The profile agrees well with classical expectations. Experiments performed with impurity pellet injection provide further evidence for classical impurity ion confinement.

  2. Theoretical Study of Radiation from a Broad Range of Impurity Ions for Magnetic Fusion Diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Safronova, Alla [Univ. of Nevada, Reno, NV (United States)

    2014-03-14

    Spectroscopy of radiation emitted by impurities plays an important role in the study of magnetically confined fusion plasmas. The measurements of these impurities are crucial for the control of the general machine conditions, for the monitoring of the impurity levels, and for the detection of various possible fault conditions. Low-Z impurities, typically present in concentrations of 1%, are lithium, beryllium, boron, carbon, and oxygen. Some of the common medium-Z impurities are metals such as iron, nickel, and copper, and high-Z impurities, such as tungsten, are present in smaller concentrations of 0.1% or less. Despite the relatively small concentration numbers, the aforementioned impurities might make a substantial contribution to radiated power, and also influence both plasma conditions and instruments. A detailed theoretical study of line radiation from impurities that covers a very broad spectral range from less than 1 Å to more than 1000 Å has been accomplished and the results were applied to the LLNL Electron Beam Ion Trap (EBIT) and the Sustained Spheromak Physics Experiment (SSPX) and to the National Spherical Torus Experiment (NSTX) at Princeton. Though low- and medium-Z impurities were also studied, the main emphasis was made on the comprehensive theoretical study of radiation from tungsten using different state-of-the-art atomic structure codes such as Relativistic Many-Body Perturbation Theory (RMBPT). The important component of this research was a comparison of the results from the RMBPT code with other codes such as the Multiconfigurational Hartree–Fock developed by Cowan (COWAN code) and the Multiconfiguration Relativistic Hebrew University Lawrence Atomic Code (HULLAC code), and estimation of accuracy of calculations. We also have studied dielectronic recombination, an important recombination process for fusion plasma, for variety of highly and low charged tungsten ions using COWAN and HULLAC codes. Accurate DR rate coefficients are needed for

  3. Impure placebo is a useless concept.

    Science.gov (United States)

    Louhiala, Pekka; Hemilä, Harri; Puustinen, Raimo

    2015-08-01

    Placebos are allegedly used widely in general practice. Surveys reporting high level usage, however, have combined two categories, 'pure' and 'impure' placebos. The wide use of placebos is explained by the high level usage of impure placebos. In contrast, the prevalence of the use of pure placebos has been low. Traditional pure placebos are clinically ineffective treatments, whereas impure placebos form an ambiguous group of diverse treatments that are not always ineffective. In this paper, we focus on the impure placebo concept and demonstrate problems related to it. We also show that the common examples of impure placebos are not meaningful from the point of view of clinical practice. We conclude that the impure placebo is a scientifically misleading concept and should not be used in scientific or medical literature. The issues behind the concept, however, deserve serious attention in future research.

  4. Overview of genotoxic impurities in pharmaceutical development.

    Science.gov (United States)

    Bercu, Joel P; Dobo, Krista L; Gocke, Elmar; McGovern, Timothy J

    2009-01-01

    This symposium focuses on the management of genotoxic impurities in the synthesis of pharmaceuticals. Recent developments in both Europe and United States require sponsors of new drug applications to develop processes to control the risks of potential genotoxic impurities. Genotoxic impurities represent a special case relative to the International Conference on Harmonisation Q3A/Q3B guidances, because genotoxicity tests used to qualify the drug substance may not be sufficient to demonstrate safety of a potentially genotoxic impurity. The default risk management approach for a genotoxic impurity is the threshold of toxicological concern unless a more specific risk characterization is appropriate. The symposium includes descriptions of industry examples where impurities are introduced and managed in the synthesis of a pharmaceutical. It includes recent regulatory developments such as the "staged threshold of toxicological concern" when administration is of short duration (eg, during clinical trials).

  5. Moessbauer Studies of Implanted Impurities in Solids

    CERN Multimedia

    2002-01-01

    Moessbauer studies were performed on implanted radioactive impurities in semiconductors and metals. Radioactive isotopes (from the ISOLDE facility) decaying to a Moessbauer isotope were utilized to investigate electronic and vibrational properties of impurities and impurity-defect structures. This information is inferred from the measured impurity hyperfine interactions and Debye-Waller factor. In semiconductors isoelectronic, shallow and deep level impurities have been implanted. Complex impurity defects have been produced by the implantation process (correlated damage) or by recoil effects from the nuclear decay in both semiconductors and metals. Annealing mechanisms of the defects have been studied. \\\\ \\\\ In silicon amorphised implanted layers have been recrystallized epitaxially by rapid-thermal-annealing techniques yielding highly supersaturated, electrically-active donor concentrations. Their dissolution and migration mechanisms have been investigated in detail. The electronic configuration of Sb donors...

  6. Method for detecting trace impurities in gases

    Science.gov (United States)

    Freund, S.M.; Maier, W.B. II; Holland, R.F.; Beattie, W.H.

    A technique for considerably improving the sensitivity and specificity of infrared spectrometry as applied to quantitative determination of trace impurities in various carrier or solvent gases is presented. A gas to be examined for impurities is liquefied and infrared absorption spectra of the liquid are obtained. Spectral simplification and number densities of impurities in the optical path are substantially higher than are obtainable in similar gas-phase analyses. Carbon dioxide impurity (approx. 2 ppM) present in commercial Xe and ppM levels of Freon 12 and vinyl chloride added to liquefied air are used to illustrate the method.

  7. Analytical advances in pharmaceutical impurity profiling.

    Science.gov (United States)

    Holm, René; Elder, David P

    2016-05-25

    Impurities will be present in all drug substances and drug products, i.e. nothing is 100% pure if one looks in enough depth. The current regulatory guidance on impurities accepts this, and for drug products with a dose of less than 2g/day identification of impurities is set at 0.1% levels and above (ICH Q3B(R2), 2006). For some impurities, this is a simple undertaking as generally available analytical techniques can address the prevailing analytical challenges; whereas, for others this may be much more challenging requiring more sophisticated analytical approaches. The present review provides an insight into current development of analytical techniques to investigate and quantify impurities in drug substances and drug products providing discussion of progress particular within the field of chromatography to ensure separation of and quantification of those related impurities. Further, a section is devoted to the identification of classical impurities, but in addition, inorganic (metal residues) and solid state impurities are also discussed. Risk control strategies for pharmaceutical impurities aligned with several of the ICH guidelines, are also discussed.

  8. Overview of impurity control and wall conditioning in NSTX

    Energy Technology Data Exchange (ETDEWEB)

    KUGEL,H.W.; MAINGI,R.; BELL,M.; BLANCHARD,W.; GATES,D.; JOHNSON,D.; KAITA,R.; KAYE,S.; MARQUEDA,R.; MENARD,J.; MUELLER,D.; ONO,M.; PENG,Y-K.M.; RAMAN,R.; RAMSEY,A.; ROQUEMORE,A.; SKINNER,C.; SABBAGH,S.; STUTMAN,D.; WAMPLER,WILLIAM R.; WILSON,J.R.; ZWEBEN,S.

    2000-05-25

    The National Spherical Torus Experiment (NSTX) started plasma operations in February 1999, and promptly achieved high current, inner wall limited, double null, and single null plasma discharges, initial Coaxial Helicity Injection, and High Harmonic Fast Wave results. NSTX is designed to study the physics of Spherical Tori (ST) in a device that can produce non-inductively sustained high-{beta} discharges in the 1 MA regime and to explore approaches toward a small, economical high power density ST reactor core. As expected, discharge reproducibility and performance were strongly affected by wall conditions. In this paper, the authors describe the internal geometry, and initial plasma discharge, impurity control, wall conditioning, erosion, and deposition results.

  9. A Spectroscopic Study of Impurity Behavior in Neutral-beam and Ohmically Heated TFTR Discharges

    Science.gov (United States)

    Stratton, B. C.; Ramsey, A. T.; Boody, F. P.; Bush, C. E.; Fonck, R. J.; Groenbner, R. J.; Hulse, R. A.; Richards, R. K.; Schivell, J.

    1987-02-01

    Quantitative spectroscopic measurements of Z{sub eff}, impurity densities, and radiated power losses have been made for ohmic- and neutral-beam-heated TFTR discharges at a plasma current of 2.2 MA and toroidal field of 4.7 T. Variations in these quantities with line-average plasma density (anti n{sub e}) and beam power up to 5.6 MW are presented for discharges on a graphite movable limiter. A detailed discussion of the use of an impurity transport model to infer absolute impurity densities and radiative losses from line intensity and visible continuum measurements is given. These discharges were dominated by low-Z impurities with carbon having a considerably higher density than oxygen, except in high-anti n{sub e} ohmic discharges, where the densities of carbon and oxygen were comparable. Metallic impurity concentrations and radiative losses were small, resulting in hollow radiated power profiles and fractions of the input power radiated being 30 to 50% for ohmic heating and 30% or less with beam heating. Spectroscopic estimates of the radiated power were in good agreement with bolometrically measured values. Due to an increase in the carbon density, Z{sub eff} rose from 2.0 to 2.8 as the beam power increased from 0 to 5.6 MW, pointing to a potentially serious dilution of the neutron-producing plasma ions as the beam power increased. Both the low-Z and metallic impurity concentrations were approximately constant with minor radius, indicating no central impurity accumulation in these discharges.

  10. Engineering estimates of impurity fluxes on the ITER port plugs

    Science.gov (United States)

    Kotov, Vladislav

    2016-10-01

    Predictions of impurity fluxes are required for design analysis of the ITER optical diagnostics. In the present paper a simplified model is proposed for calculation of the neutral impurity fluxes on the recessed surfaces which are not in direct contact with plasma. The method is based on the Monte-Carlo simulation of the neutral particles transport in prescribed and fixed plasma background. The plasma parameters are projected from experimental observations, scalings and ITER modelling results. Blobs are approximated as stationary hot species. Results of 2D simulations with toroidally uniform wall and of the ‘2.5D model’ are presented. In this latter the 3D geometry of ports is implemented, but details of the incident ion flux distribution on the first wall panels are neglected. The calculated worst case gross deposition rate of Be in the middle of the port plug faces reaches almost 0.1 nm s-1. At the same time, the obtained Be erosion to deposition ratio at those locations is always larger than 5, indicating high probability of net erosion conditions there.

  11. An efficient method combining thermal annealing and acid leaching for impurities removal from silica intended for photovoltaic application

    Indian Academy of Sciences (India)

    M Khalifa; M Hajji; H Ezzaouia

    2013-11-01

    This work investigates the photothermal treatment of silica sand to reduce impurities to a low level suitable for the production of acceptable solar grade silicon for photovoltaic application. It describes experiment carried out by using a tungsten lamp furnace to purify silica under controlled atmosphere. This process enables to attract impurities to the surface of silica grains where they can be easily extracted by partial dissolution in an acid mixture. Thus obtained silica was investigated by inductively coupled plasma atomic emission spectrometry (ICP–AES) method. Major impurities present in silica sand were Al, K, Fe, Na, Ca, Mg and B. Among the new products, almost major impurities were removed effectively. Indeed purity degree, given by characterization of ICP–AES, passes from 99.76 to 99.96% and the average impurity removal efficiency is 83.33%.

  12. Impact of fuelling and impurity on pedestal dynamics and instabilities in the HL-2A tokamak

    Science.gov (United States)

    Zhong, W. L.; Zou, X. L.; Gao, J. M.; Shi, Z. B.; Feng, B. B.; Cui, Z. Y.; Xu, M.; Shen, Y.; Dong, J. Q.; Ding, X. T.; Duan, X. R.; Liu, Yong; HL-2A Team

    2017-01-01

    In recent experiments of the HL-2A tokamak, the effect on the pedestal dynamics by the plasma fuelling with supersonic molecular beam injection (SMBI) has been intensively investigated. Experimental results in several tokamaks suggested that SMBI is a promising technique for ELM mitigation. In addition to the fuelling, the impact of impurities on the pedestal dynamics and instabilities has been investigated in HL-2A. Experimental results have shown that during the H-mode phase, a broadband electromagnetic (EM) turbulence was driven by peaked impurity density profile at the edge plasma region, and governed by double critical gradients of the impurity density. The absolute value of the threshold in positive gradient region is much lower than that in the negative region. This strong asymmetry in the critical gradients has been predicted by theoretical simulation. The results reveal that pedestal dynamics and heat loads can be actively controlled by exciting or changing pedestal instabilities.

  13. Impurity ion diagnostics in the GAMMA 10 tandem mirror

    Energy Technology Data Exchange (ETDEWEB)

    Yoshikawa, Masayuki; Okamoto, Yuuji; Kawamori, Eiichiro [Plasma Research Center, University of Tsukuba, Tsukuba, Ibaraki (Japan)] (and others)

    2000-07-01

    We constructed some spectroscopic measurement systems that cover the wavelength range from soft X-ray (SX) to visible lights. We have observed the absolute impunity line intensities, Doppler line broadenings, Doppler shifts by ultraviolet and visible spectrograph and time dependent radial profiles of the impurity lines by the vacuum ultraviolet (VUV) and the SX spectrographs. We determined the radiation loss in the wavelength range from visible to VUV and carbon ion density. These spectroscopic systems could be powerful tools to diagnose the GAMMA 10 plasma in a long pulse operation. (author)

  14. Cryogenic Laser Calorimetry for Impurity Analysis

    Science.gov (United States)

    Swimm, R. T.

    1985-01-01

    The results of a one-year effort to determine the applicability of laser-calorimetric spectroscopy to the study of deep-level impurities in silicon are presented. Critical considerations for impurity analysis by laser-calorimetric spectroscopy are discussed, the design and performance of a cryogenic laser calorimeter is described, and measurements of background absorption in high-purity silicon are presented.

  15. Nuclear relaxation via paramagnetic impurities

    CERN Document Server

    Dzheparov, F S; Jacquinot, J F

    2002-01-01

    First part of the work contains a calculation of the kinetics of nuclear relaxation via paramagnetic impurities for systems with arbitrary (including fractal) space dimension d basing on ideas, which run current for 3d objects now. A new mean-field-type theory is constructed in the second part of the work. It reproduces all results of the first part for integer d and gives a possibility to describe the process for longer time, when a crossover to Balagurov-Waks asymptotics starts to develop. Solutions of the equations of the new theory are constructed for integer d. To obtain the solutions a method of calculation of the low-energy and long-wave asymptotics for T matrix of potential scattering out of the mass shell for singular repulsive potentials is developed

  16. Analytical control of process impurities in Pazopanib hydrochloride by impurity fate mapping.

    Science.gov (United States)

    Li, Yan; Liu, David Q; Yang, Shawn; Sudini, Ravinder; McGuire, Michael A; Bhanushali, Dharmesh S; Kord, Alireza S

    2010-08-01

    Understanding the origin and fate of organic impurities within the manufacturing process along with a good control strategy is an integral part of the quality control of drug substance. Following the underlying principles of quality by design (QbD), a systematic approach to analytical control of process impurities by impurity fate mapping (IFM) has been developed and applied to the investigation and control of impurities in the manufacturing process of Pazopanib hydrochloride, an anticancer drug approved recently by the U.S. FDA. This approach requires an aggressive chemical and analytical search for potential impurities in the starting materials, intermediates and drug substance, and experimental studies to track their fate through the manufacturing process in order to understand the process capability for rejecting such impurities. Comprehensive IFM can provide elements of control strategies for impurities. This paper highlights the critical roles that analytical sciences play in the IFM process and impurity control. The application of various analytical techniques (HPLC, LC-MS, NMR, etc.) and development of sensitive and selective methods for impurity detection, identification, separation and quantification are highlighted with illustrative examples. As an essential part of the entire control strategy for Pazopanib hydrochloride, analytical control of impurities with 'meaningful' specifications and the 'right' analytical methods is addressed. In particular, IFM provides scientific justification that can allow for control of process impurities up-stream at the starting materials or intermediates whenever possible.

  17. Impurity levels, impurity bands, excited impurity bands, and band tails: The electronic density of states in quantum wells and heterostructures

    Science.gov (United States)

    Serre, J.; Ghazali, A.; Gold, A.

    1989-04-01

    We have investigated in quantum wells (QW's) and heterostructures (HS's) the modification of the electronic structure near the band edge, which is induced by selective doping. The density of states has been calculated as a function of the relevant parameters, namely, carrier and impurity concentrations (and depletion concentrations for HS's), QW width, and impurity position. Using a multiple-scattering method which includes a finite-range screened potential and impurity concentration to all orders, we have succeeded in obtaining ground-state and excited-state impurity bands (IB's). We observed these bands merging gradually with the lowest conduction subband as the impurity concentration is increased, leading to the formation of a band tail into the energy gap. Other main results obtained for different values of the parameters are the binding energy for a single impurity, the widths and energy shifts of ground- and excited-state IB's, and the contribution of the electron-impurity interaction to the gap shrinkage in the band-tail regime. Our results are compared with experiments and other theories.

  18. Crack-impurity interactions and their role in the embrittlement of Fe alloy crystals charged with light elements

    Energy Technology Data Exchange (ETDEWEB)

    Narita, N. (Dept. of Metallurgy, Kyoto Univ. (Japan)); Shiga, T. (Dept. of Metallurgy, Kyoto Univ. (Japan)); Higashida, K. (Dept. of Metallurgy, Kyoto Univ. (Japan))

    1994-03-31

    The effect of mobile impurity doping on fracture behaviour has been investigated using plasma charging of light elements for Fe-2.5wt.%Si alloy crystals with particular attention to the role of crack-impurity elastic interactions. Fe-Si crystals are markedly embrittled by plasma charging of helium as well as hydrogen at around room temperature, this being accompanied by slow crack growth. Neon charging contributes little to the embrittlement, but argon charging does not contribute. The crystals are also embrittled by nitrogen charging in the tests at 450 K and exhibit slow crack growth during the tests. Elastic analyses indicate that crack-impurity interactions are induced not only by the applied K[sub I] field but also by the stress modification due to ambient impurities in the presence of a crack. The interactions serve effectively to concentrate mobile impurities ahead of a crack tip, leading to the increase in the local stress intensity k[sub I]. The effect of interstitial impurities on crack extension is discussed in connection with the modification of stress states due to impurities around a crack tip. (orig.)

  19. Density and impurity profile behaviours in HL-2A tokamak with different gas fuelling methods

    Institute of Scientific and Technical Information of China (English)

    Cui Zheng-Ying; Zhou Yan; Li Wei; Feng Bei-Bin; Sun Ping; Dong Chun-Feng; Liu Yi; Hong Wen-Yu; Yang Qing-Wei; Ding Xuan-Tong; Duan Xu-Ru

    2009-01-01

    The electron density profile peaking and the impurity accumulation in the HL-2A tokamak plasma are observed when three kinds of fuelling methods are separately used at different fuelling particle locations.The density profile becomes more peaked when the line-averaged electron density approaches the Greenwald density limit nG and,consequently,impurity accumulation is often observed.A linear increase regime in the density range ne<0.6nG and a saturation regime in ne>0.6nG are obtained.There is no significant difference in achieved density peaking factor fne between the supersonic molecular beam injection (SMBI) and gas puffing into the plasma main chamber.However,the achieved fne is relatively low,in particular,in the case of density below 0.7nG,when the working gas is puffed into the divertor chamber.A discharge with a density as high as 1.2nG,i.e.ne=1.2nG,can be achieved by SMBI just after siliconization as a wall conditioning.The metallic impurities,such as iron and chromium,also increase remarkably when the impurity accumulation happens.The mechanism behind the density peaking and impurity accumulation is studied by investigating both the density peaking factor versus the effective collisionality and the radiation peaking versus density peaking.

  20. Influence of iron impurities on defected graphene

    Energy Technology Data Exchange (ETDEWEB)

    Faccio, Ricardo; Pardo, Helena [Centro NanoMat, Cryssmat-Lab, DETEMA, Polo Tecnológico de Pando, Facultad de Química, Universidad de la República, Cno. Saravia s/n, CP 91000 Pando (Uruguay); Centro Interdisciplinario en Nanotecnología, Química y Física de Materiales, Espacio Interdisciplinario, Universidad de la República, Montevideo (Uruguay); Araújo-Moreira, Fernando M. [Materials and Devices Group, Department of Physics, Universidade Federal de São Carlos, SP 13565-905 (Brazil); Mombrú, Alvaro W., E-mail: amombru@fq.edu.uy [Centro NanoMat, Cryssmat-Lab, DETEMA, Polo Tecnológico de Pando, Facultad de Química, Universidad de la República, Cno. Saravia s/n, CP 91000 Pando (Uruguay); Centro Interdisciplinario en Nanotecnología, Química y Física de Materiales, Espacio Interdisciplinario, Universidad de la República, Montevideo (Uruguay)

    2015-03-01

    Highlights: • The interaction among a multivacancy graphene system and iron impurities is studied. • The studied iron impurities were single atom and tetrahedral and octahedral clusters. • DFT calculations using the VASP code were performed. • The embedding of Fe affects the structure and electronic behavior in the graphene. • Half metal or semimetal behavior can be obtained, depending on the Fe impurities. - Abstract: The aim of this work is to study the interaction of selected iron cluster impurities and a multivacancy graphene system, in terms of the structural distortion that the impurities cause as well as their magnetic response. While originally, the interaction has been limited to vacancies and isolated metallic atoms, in this case, we consider small iron clusters. This study was undertaken using Density Functional Theory (DFT) calculations. The influence of the iron impurities in the electronic structure of the vacant graphene system is discussed. The main conclusion of this work is that the presence of iron impurities acts lowering the magnetic signal due to the occurrence of spin pairing between carbon and iron, instead of enhancing the possible intrinsic carbon magnetism.

  1. Paramagnetic Attraction of Impurity-Helium Solids

    Science.gov (United States)

    Bernard, E. P.; Boltnev, R. E.; Khmelenko, V. V.; Lee, D. M.

    2003-01-01

    Impurity-helium solids are formed when a mixture of impurity and helium gases enters a volume of superfluid helium. Typical choices of impurity gas are hydrogen deuteride, deuterium, nitrogen, neon and argon, or a mixture of these. These solids consist of individual impurity atoms and molecules as well as clusters of impurity atoms and molecules covered with layers of solidified helium. The clusters have an imperfect crystalline structure and diameters ranging up to 90 angstroms, depending somewhat on the choice of impurity. Immediately following formation the clusters aggregate into loosely connected porous solids that are submerged in and completely permeated by the liquid helium. Im-He solids are extremely effective at stabilizing high concentrations of free radicals, which can be introduced by applying a high power RF dis- charge to the impurity gas mixture just before it strikes the super fluid helium. Average concentrations of 10(exp 19) nitrogen atoms/cc and 5 x 10(exp 18) deuterium atoms/cc can be achieved this way. It shows a typical sample formed from a mixture of atomic and molecular hydrogen and deuterium. It shows typical sample formed from atomic and molecular nitrogen. Much of the stability of Im-He solids is attributed to their very large surface area to volume ratio and their permeation by super fluid helium. Heat resulting from a chance meeting and recombination of free radicals is quickly dissipated by the super fluid helium instead of thermally promoting the diffusion of other nearby free radicals.

  2. Impurity atoms on view in cuprates

    Directory of Open Access Journals (Sweden)

    J.C. Séamus Davis

    2002-04-01

    Full Text Available Impurity atoms in a material are usually viewed as a problem because they can result in non-ideal properties. However, they can sometimes be used to advantage when attempting to understand new materials. This is because the interactions of an impurity atom with the material reveal detailed information on the local electronic environment. In this paper we discuss scanning tunneling microscopy studies of the atomic-scale effects of individual Ni and Zn impurity atoms on the cuprate high critical temperature superconductors.

  3. Divertor power spreading in DEMO reactor by impurity seeding

    Energy Technology Data Exchange (ETDEWEB)

    Zagórski, Roman, E-mail: Roman.Zagorski@ipplm.pl; Gałązka, Krzysztof; Ivanova-Stanik, Irena

    2016-11-01

    Highlights: • The COREDIV code has been used to simulate DEMO inductive discharges with different impurity seeding (Ne, Ar, Kr) and different sputtering models (with and w/o prompt re-deposition process). • It has been shown that only for Ar and Kr seeding it is possible to achieve H-mode plasma operation with acceptable level of the power to the tungsten target plates. • For neon seeding, such regime of operation seems not to be possible. • Prompt re-deposition model extends the DEMO operation window. - Abstract: Numerical simulation with COREDIV code of DEMO H-mode discharges (tungsten divertor and wall) are performed considering the influence of seeding impurities with different atomic numbers: Ne, Ar and Kr on the DEMO scenarios. The approach is based on integrated numerical modeling using the COREDIV code, which self-consistently solves radial transport equations in the core region and 2D multi-fluid transport in the SOL. In this paper we focus on investigations how the operational domain of DEMO can be influenced by seeding gasses. Simulations with the updated prompt re-deposition model implemented in the code show that only for Ar and Kr, for high enough radial diffusion in the SOL, it is possible to achieve H-mode plasma operation (power to the SOL> L-H transition threshold power) with acceptable level of the power to the target plates. For neon seeding such regime of operation seems not to be possible.

  4. Experimental investigation of the nonlinear evolution of an impurity-driven drift wave

    Energy Technology Data Exchange (ETDEWEB)

    Allen, G.R.; Yamada, M.; Rewoldt, G.; Tang, W.M.

    1982-04-01

    An impurity-driven drift wave is observed to be destabilized by the reversed density gradient of a singly-ionized heavy-impurity-ion population in a Q-machine plasma. The evolution of the instability is investigated as it progresses from the initial linear exponential growth phase, into a nonlinear saturated state, whereupon strong radially outward anomalous diffusion is observed. The relationship between the anomalous diffusion coefficient and the wave amplitude is in agreement with estimates obtained from the nonlinear drift-wave turbulence theory of Dupree.

  5. Impurity removal process for high-purity silica production by acid leaching

    Directory of Open Access Journals (Sweden)

    Ezzaouia H.

    2012-06-01

    Full Text Available In our days obtaining silica sand with very high purity is a primordial stage in photovoltaic industry. The effects of acids on the removal of impurity from silica sand have been studied using leaching acids: mixture composed of HF/HCl/H2O with a volume composition of (1:7:24.The obtained material was characterized using Ultraviolet-Visible absorbance (UV-Vis and Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES. Results of the application of this technique show a significant reduction of the amounts of undesirable impurities present in natural silica (such as Co, Fe, Ca, Al, Mg ….

  6. Measuring one-dimensional and two-dimensional impurity density profiles on TEXTOR using combined charge exchange-beam emission spectroscopy and ultrasoft x-ray tomography

    Science.gov (United States)

    De Bock, M.; Jakubowska, K.; Hellermann, M. von; Jaspers, R.; Donné, A. J. H.; Shmaenok, L.

    2004-10-01

    Two techniques are presented that allow us to measure impurity density profiles in the TEXTOR tokamak plasma. The one-dimensional profiles are gathered by charge exchange recombination spectroscopy (CXRS) in combination with beam emission spectroscopy (BES). Combining CXRS and BES eliminate the need for absolute calibration. For two-dimensional profiles an ultrasoft x-ray tomography system has been developed. The system is spectrally resolved and produces local emissivity profiles of several ionization stages of impurities. Both systems are presently being commissioned. They are complementary and give an insight into the impurity distribution and transport in plasmas.

  7. Glycolic acid physical properties and impurities assessment

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D. P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Pickenheim, B. R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Hay, M. S. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); BIBLER, N. E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-08-09

    This document has been revised to add analytical data for fresh, 1 year old, and 4 year old glycolic acid as recommended in Revision 2 of this document. This was needed to understand the concentration of formaldehyde and methoxyacetic acid, impurities present in the glycolic acid used in Savannah River National Laboratory (SRNL) experiments. Based on this information, the concentration of these impurities did not change during storage. These impurities were in the glycolic acid used in the testing included in this report and in subsequent testing using DuPont (now called Chemours) supplied Technical Grade 70 wt% glycolic acid. However, these impurities were not reported in the first two versions of this report. The Defense Waste Processing Facility (DWPF) is planning to implement a nitric-glycolic acid flowsheets to increase attainment to meet closure commitment dates during Sludge Batch 9. In fiscal year 2009, SRNL was requested to determine the physical properties of formic and glycolic acid blends.

  8. Effects of impurity location on the impurity bands and their spectral densities in quantum wells

    Science.gov (United States)

    Gold, A.; Ghazali, A.; Serre, J.

    1989-09-01

    The electronic density of states and the spectral density of quantum wells are calculated as functions of the impurity position zi. A multiple-scattering method which accounts for the formation of impurity bands is used. The study of the spectral densities provides us with the behavior of the averaged wave functions of the ground- and excited-state impurity bands in the k space. We demonstrate that our approach can be used to study hybridization effects between different bands.

  9. Quantum critical points in quantum impurity systems

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun Jung [Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Universitaet Augsburg (Germany); Bulla, Ralf [Theoretische Physik III, Elektronische Korrelationen und Magnetismus, Universitaet Augsburg (Germany)]. E-mail: bulla@cpfs.mpg.de

    2005-04-30

    The numerical renormalization group method is used to investigate zero-temperature phase transitions in quantum impurity systems, in particular in the soft-gap Anderson model, where an impurity couples to a non-trivial fermionic bath. In this case, zero-temperature phase transitions occur between two different phases whose fixed points can be built up of non-interacting single-particle states. However, the quantum critical point cannot be described by non-interacting fermionic or bosonic excitations.

  10. Quantum critical points in quantum impurity systems

    Science.gov (United States)

    Lee, Hyun Jung; Bulla, Ralf

    2005-04-01

    The numerical renormalization group method is used to investigate zero-temperature phase transitions in quantum impurity systems, in particular in the soft-gap Anderson model, where an impurity couples to a non-trivial fermionic bath. In this case, zero-temperature phase transitions occur between two different phases whose fixed points can be built up of non-interacting single-particle states. However, the quantum critical point cannot be described by non-interacting fermionic or bosonic excitations.

  11. Parametrically Driven Nonlinear Oscillators with an Impurity

    Institute of Scientific and Technical Information of China (English)

    张卓; 唐翌

    2002-01-01

    By virtue of the method of multiple scales, we study a chain of parametrically driven nonlinear oscillators with a mass impurity. An equation is presented to describe the nonlinear wave of small amplitude in the chain.In our derivation, the equation is applicable to any eigenmode of coupled pendulum. Our result shows that a nonpropagation soliton emerges as the lowest or highest eigenmode of coupled pendulum is excited, and the impurity tends to pin the nonpropagation soliton excitation.

  12. Effects of helium impurities on superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Selle, J.E.

    1977-07-01

    A review of the literature on the effects of helium impurities on superalloys at elevated temperatures was undertaken. The actual effects of these impurities vary depending on the alloy, composition of the gas atmosphere, and temperature. In general, exposure in helium produces significant but not catastrophic changes in the structure and properties of the alloys. The effects of these treatments on the structure, creep, fatigue, and mechanical properties of the various alloys are reviewed and discussed. Suggestions for future work are presented.

  13. 电感耦合等离子体光谱法测定石煤钒矿多种元素%determination of impurities elements in stone coal Vanadium ore by inductively coupled Plasma spectrometry

    Institute of Scientific and Technical Information of China (English)

    张歌; 赵学沛; 沙艳梅; 王明军; 何雪梅

    2014-01-01

    in this research, samples are decomposed by hydrochloric acid, nitric acid, hydrofluoric acid, perchloric acid to, and the main, second, and trace elements-al, Fe, ca, Mg, P, ti, s, co, cu, Mn, ni and V are determined by inductively coupled plasma emission spectrometry (icp-aes). this research for the first time to burn samples over 550℃before determining the samples according to the experimental method; new feature is adding hydrogen peroxide after the samples dissolved, and hydrogen peroxide is both oxidizing and reducing, can reduce some elements to dissolve them, without any interference components, making the determination results more accurate and reliable;the tests of phosphorus and other elements are united into one experimental process, greatly reducing the labor intensity, saving the cost, which is suitable for the large number of sample analysis. this method is simple, fast, and the result is satisfactory.%用盐酸-硝酸-氢氟酸-高氯酸分解石煤钒矿试样,电感耦合等离子体发射光谱法(icP-aes)测定主、次、痕量元素al、Fe、ca、Mg、P、ti、s、co、cu、Mn、ni、V。本研究课题首次开展550℃灼烧样品后再按实验方法进行测定样品;新特点是在样品溶解好后加入过氧化氢,过氧化氢既有氧化性又有还原性,既能还原某些元素使其沉淀溶解,又没引进干扰成分,使测定结果更加准确可靠;磷与其他元素的测试合并为一次实验过程,大大减少了劳动强度,节约了成本,适合于大批样品的分析测试。方法准确、可靠,提高了工作效率,结果令人满意。

  14. Local chemistry of Al and P impurities in silica

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Stokbro, Kurt

    2000-01-01

    The local structure around Al and P impurities in silica is investigated using density-functional theory. Two distinct cases are considered: impurities substituting for a Si atom in alpha quartz, and impurities implanted in a stoichiometric alpha-quartz crystal. Both impurity elements are found t...

  15. Determination of eight impurity elements in industrial silicon by inductively coupled plasma atomic emission spectrometry%电感耦合等离子体原子发射光谱法测定工业硅中8种杂质元素

    Institute of Scientific and Technical Information of China (English)

    张云晖; 杨晓静; 亢若谷; 赵建为; 金波

    2013-01-01

    The inert sample injection system resistant hydrofluoric acid of inductively coupled plasma atomic emission spectrometer was used. The sample solution was injected directly without removing hydrofluoric acid and silicon matrix after sample was dissolved in hydrofluoric acid, nitric acid and perchloric acid. Eight impurities including iron, aluminum, calcium, titanium, manganese, nickel, boron and phosphorus in industrial silicon powder were simultaneously determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Most of matrix silicon had been volatilized and removed in sample dissolution process, so the matrix effect had no influence on the determination of i-ron, aluminum, calcium, titanium, manganese and nickel. However, the determination of boron and phosphorus was still affected, which could be eliminated by vertical observation method. The detection limit of the method was calculated by three times of standard deviation of blank. The detection limits (w/%) for iron, aluminum, calcium, titanium, manganese, nickel, boron and phosphorus were 0. 004, 0. 001, 0. 004, 0. 001, 0. 0001, 0. 0001, 0. 000 04 and 0. 000 06, respectively. The proposed method was applied to the determination of eight impurities in industrial silicon. The found results were consistent with the certified values or those obtained by standard method (GB/T 14849. 4-2008).%采用电感耦合等离子体原子发射光谱仪的耐氢氟酸惰性进样系统,在样品用氢氟酸、硝酸、高氯酸溶解完全后无需赶尽氢氟酸和硅基体,直接进样,电感耦合等离子体原子发射光谱法同时测定了工业硅粉中铁、铝、钙、钛、锰、镍、硼和磷8种杂质元素.因为在溶样过程中大部分基体硅已挥发除去,基体效应对铁、铝、钙、钛、锰、镍的测定没有影响,但是对硼和磷的测定仍有影响,这种影响可以采用垂直观测方式克服.按照空白值的3倍标准偏差计算方法的检测限,得到

  16. Interactions of Pellet with Reactor Relevant Plasma

    Institute of Scientific and Technical Information of China (English)

    PENGLilin; DENGBaiquan; YANJiancheng

    2003-01-01

    Extended algorithm has been developed for ablation rate calculations of Li, Be, B impurity pellets and five combinations of solid isotopic hydrogenic H2, HD, D2, DT, T2 pellets. Numerical calculations have been performed for reactor relevant plasma.

  17. Vacuum ultraviolet impurity spectroscopy on the Alcator C-Mod tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Reinke, M. L.; Howard, N. T.; Podpaly, Y.; Rice, J. E.; Terry, J. L. [Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139 (United States); Beiersdorfer, P.; Magee, E. W. [Physics Division, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    2010-10-15

    Vacuum ultraviolet spectroscopy is used on the Alcator C-Mod tokamak to study the physics of impurity transport and provide feedback on impurity levels to assist experimental operations. Sputtering from C-Mod's all metal (Mo+W) plasma facing components and ion cyclotron range of frequency antenna and vessel structures (sources for Ti, Fe, Cu, and Ni), the use of boronization for plasma surface conditioning and Ar, Ne, or N{sub 2} gas seeding combine to provide a wealth of spectroscopic data from low-Z to high-Z. Recently, a laser blow-off impurity injector has been added, employing CaF{sub 2} to study core and edge impurity transport. One of the primary tools used to monitor the impurities is a 2.2 m Rowland circle spectrometer utilizing a Reticon array fiber coupled to a microchannel plate. With a 600 lines/mm grating the 80<{lambda}<1050 A range can be scanned, although only 40-100 A can be observed for a single discharge. Recently, a flat-field grating spectrometer was installed which utilizes a varied line spacing grating to image the spectrum to a soft x-ray sensitive Princeton Instruments charge-coupled device camera. Using a 2400 lines/mm grating, the 10<{lambda}<70 A range can be scanned with 5-6 nm observed for a single discharge. A variety of results from recent experiments are shown that highlight the capability to track a wide range of impurities.

  18. Impurity content of reduced-activation ferritic steels and a vanadium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Klueh, R.L.; Grossbeck, M.L.; Bloom, E.E. [Oak Ridge National Lab., TN (United States)

    1997-04-01

    Inductively coupled plasma mass spectrometry was used to analyze a reduced-activation ferritic/martensitic steel and a vanadium alloy for low-level impurities that would compromise the reduced-activation characteristics of these materials. The ferritic steel was from the 5-ton IEA heat of modified F82H, and the vanadium alloy was from a 500-kg heat of V-4Cr-4Ti. To compare techniques for analysis of low concentrations of impurities, the vanadium alloy was also examined by glow discharge mass spectrometry. Two other reduced-activation steels and two commercial ferritic steels were also analyzed to determine the difference in the level of the detrimental impurities in the IEA heat and steels for which no extra effort was made to restrict some of the tramp impurities. Silver, cobalt, molybdenum, and niobium proved to be the tramp impurities of most importance. The levels observed in these two materials produced with present technology exceeded the limits for low activation for either shallow land burial or recycling. The chemical analyses provide a benchmark for the improvement in production technology required to achieve reduced activation; they also provide a set of concentrations for calculating decay characteristics for reduced-activation materials. The results indicate the progress that has been made and give an indication of what must still be done before the reduced-activation criteria can be achieved.

  19. Gettering of metal impurities in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Schroeter, W.; Spiecker, E.; Apel, M. [Universitaet Goettingen (Germany)

    1995-08-01

    Gettering means the removal of metallic impurities from the device-active area of the wafer by transport to a predesigned region-called gettering layer (GL). We introduce an interface at z = d{sub GL}, at which the effect of the gettering mechanism on the metal impurity distribution in the wafer is quantified, e.g. by specifying currents or by interfacial reactions of metal impurities, self interstitials etc. between GL and wafer. In response metal impurities will diffuse out of the wafer into the gettering layer. Following such a concept, in general three species of the metal impurity (M) are involved in gettering: M{sub p} {l_arrow} M{sub i} {l_arrow} M{sub GL}. M{sub p} denotes immobile species in the wafer, which are precipitated into suicides or segregated at extended defects or whose diffusivity is too small to contribute noticeably to transport during the gettering procedure - like many substitutional metal species.

  20. Oscillatory impurity potential induced dynamics of doped quantum dots: Analysis based on coupled influence of impurity coordinate and impurity influenced domain

    Energy Technology Data Exchange (ETDEWEB)

    Datta, Nirmal Kumar [Department of Physics, Suri Vidyasagar College, Suri, Birbhum 731 101, West Bengal (India); Ghosh, Manas, E-mail: pcmg77@rediffmail.com [Department of Chemistry, Physical Chemistry Section, Visva Bharati University, Santiniketan, Birbhum 731 235, West Bengal (India)

    2010-06-16

    Graphical abstract: The pattern of time evolution of eigenstates of a repulsive impurity doped quantum dot is explored. We have considered Gaussian impurity centers. Under a periodically fluctuating impurity potential, the system reveals a long time dynamics that is undulatory in nature. Coupled to the dopant location, the domain of influence of the impurity potential affects the separation between the eigenstates of the unperturbed system. The investigation points to a threshold value of spatial extension of impurity potential. Above this threshold value, the dopant location becomes important in monitoring the minimum value of impurity potential required to cause excitation. - Abstract: We explore the pattern of time evolution of eigenstates of a repulsive impurity doped quantum dot. The quantum dot is 2-dimensional and contains one electron which is harmonically confined. We have considered Gaussian impurity centers. A static transverse magnetic field is also present. Under a periodically fluctuating impurity potential, the system reveals a long time dynamics that is undulatory in nature. Coupled to the dopant location, the domain of influence of the impurity potential affects the separation between the eigenstates of the unperturbed system. The investigation points to a threshold value of spatial extension of impurity potential. Above this threshold value, the dopant location becomes important in monitoring the minimum value of impurity potential required to cause excitation.

  1. Atomic spectroscopy on fusion relevant ions and studies of light impurities in the JET tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Tunklev, M

    1999-03-01

    The spectrum and energy levels of C IV and the 3l-4l system of the Mg-like ions in the iron group elements have been investigated. This has led to several hundred identified transitions, many of them previously unknown. Using the Charge Exchange Diagnostic system at JET, ion temperatures, rotation velocities and densities have been derived from visible spectroscopic measurements on fully ionised light impurities, such as He, C, N and Ne. The existence of plume contribution from beam produced hydrogen-like ions has been proven beyond any doubt to affect the deduction of the active charge exchange signal of He II. In the case of C VI the plume signal was estimated to be at least a factor of five lower than the active charge exchange signal. Line integrated passive charge exchange emission between neutral background atoms and fully stripped impurity ions has been investigated and modelled. When the synthetic spectrum is fitted into the experimentally detected spectra the neutral background density can be deduced. The importance of including background atoms (H, D and T) as charge exchange donors, not only in state 2s, but also in state 1s, has shown to be crucial in high temperature shots. Transport of light impurities has been studied with gas puff injections into steady state H-mode plasmas. The results suggest that light impurities are transported as described by the neo-classical Pfirsch-Schlueter regime at the edge, whilst in the centre, sawtoothing, preferably to Banana transport, is mixing the plasma and increases the measured values on the diffusion. For the peaking of impurities in a steady state plasma an anomalous treatment was more in agreement with the experimental data. Certain confinement information, previously predicted theoretically as a part of the peaking equation, has been experimentally verified

  2. Study and simulation of carbon impurity dynamics near the ergodic divertor in Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Giannella, R.; Cordier, J.J.; Corre, Y.; Ghendrih, P.; Guirlet, R.; Gunn, J. [Association Euratom-CEA, CEA/Cadarache, Dept. de Recherches sur la Fusion Controlee (DRFC), 13 - Saint-Paul-lez-Durance (France); Hogan, J. [Oak Ridge National Lab., TN (United States)

    1999-10-15

    In the past few years, effects induced by the ergodic dive such as impurity screening and transport modifications in the plasma edge have been used to achieve high radiation, low contamination regimes. A crucial issue in understanding these effects is that of impurity generation and propagation across the plasma edge, especially in the vicinity of the Ergodic Divertor (ED) neutralizer plates. A variety of diagnostic tools and techniques are used for this purpose. In the case of Tore Supra, interpretation of spectroscopic data is strongly complicated by the complex geometry of the ED, leading among other effects to the total lack of uniformity of the sources. Indeed, due to the specific pattern of impurity sources on the neutralizers and to their particular orientation with respect to the local magnetic field, densities of lowly ionised impurities are deeply modulated on the sub-centimeter scale in both directions perpendicular to the magnetic field. Because of this, accurate 3-D simulations are essential for the evaluation of experimental signals. (authors)

  3. Hard sphere crystal nucleation and growth near large spherical impurities

    Science.gov (United States)

    de Villeneuve, V. W. A.; Verboekend, D.; Dullens, R. P. A.; Aarts, D. G. A. L.; Kegel, W. K.; Lekkerkerker, H. N. W.

    2005-11-01

    We report how large spherical impurities affect the nucleation and growth of hard sphere colloidal crystals. Both the impurities and the colloids are fluorescently labelled polymethylmetacrylate particles and are dispersed in an optically and density matching solvent mixture. Crystal growth, initiated either at the impurity surface, or at the sample bottom, was studied by imaging sequences of two-dimensional xy-slices in the plane of the impurity's centre of mass with a laser scanning confocal microscope. At least two factors determine whether a large impurity can function as a seed for heterogeneous nucleation: timescales and impurity curvature. The curvature needs to be sufficiently low for crystal nuclei to form on the impurity surface. If bulk crystal growth has already approached the impurity, bulk growth is dominant over growth of crystallites on the impurity surface. Such surface crystallites eventually reorient to adapt to the overall bulk crystal symmetry.

  4. Removal Of Volatile Impurities From Copper Concentrates

    Energy Technology Data Exchange (ETDEWEB)

    Winkel, L.; Schuler, A.; Frei, A.; Sturzenegger, M.

    2005-03-01

    To study the removal of volatile impurities from two different copper concentrates they have been heated on a thermo balance to temperatures between 900 and 1500 C. This sample treatment revealed that both concentrates undergo strong weight losses at 500 and 700 C. They were attributed to the removal of sulfur. Elemental analyses of the residues by ICP spectrometry have shown that the thermal treatment efficiently removes the volatile impurities. Already below 900 C most of the arsenic is removed by evaporation, the largest fraction of lead and zinc is removed in the temperature interval of 1300-1500 C. It was observed that quartz in the concentrate leads to the formation of a silicon-enriched phase besides a metal rich sulfide phase. The former is interpreted as an early stage of a silicate slag. Elemental analysis showed that the formation of this distinct slag phase does not hinder the efficient removal of volatile impurities. (author)

  5. Strong quantum scarring by local impurities

    Science.gov (United States)

    Luukko, Perttu J. J.; Drury, Byron; Klales, Anna; Kaplan, Lev; Heller, Eric J.; Räsänen, Esa

    2016-11-01

    We discover and characterise strong quantum scars, or quantum eigenstates resembling classical periodic orbits, in two-dimensional quantum wells perturbed by local impurities. These scars are not explained by ordinary scar theory, which would require the existence of short, moderately unstable periodic orbits in the perturbed system. Instead, they are supported by classical resonances in the unperturbed system and the resulting quantum near-degeneracy. Even in the case of a large number of randomly scattered impurities, the scars prefer distinct orientations that extremise the overlap with the impurities. We demonstrate that these preferred orientations can be used for highly efficient transport of quantum wave packets across the perturbed potential landscape. Assisted by the scars, wave-packet recurrences are significantly stronger than in the unperturbed system. Together with the controllability of the preferred orientations, this property may be very useful for quantum transport applications.

  6. Magnetic impurities in spin-split superconductors

    Science.gov (United States)

    van Gerven Oei, W.-V.; Tanasković, D.; Žitko, R.

    2017-02-01

    Hybrid semiconductor-superconductor quantum dot devices are tunable physical realizations of quantum impurity models for a magnetic impurity in a superconducting host. The binding energy of the localized subgap Shiba states is set by the gate voltages and external magnetic field. In this work we discuss the effects of the Zeeman spin splitting, which is generically present both in the quantum dot and in the (thin-film) superconductor. The unequal g factors in semiconductor and superconductor materials result in respective Zeeman splittings of different magnitude. We consider both classical and quantum impurities. In the first case we analytically study the spectral function and the subgap states. The energy of bound states depends on the spin-splitting of the Bogoliubov quasiparticle bands as a simple rigid shift. For the case of collinear magnetization of impurity and host, the Shiba resonance of a given spin polarization remains unperturbed when it overlaps with the branch of the quasiparticle excitations of the opposite spin polarization. In the quantum case, we employ numerical renormalization group calculations to study the effect of the Zeeman field for different values of the g factors of the impurity and of the superconductor. We find that in general the critical magnetic field for the singlet-doublet transition changes nonmonotonically as a function of the superconducting gap, demonstrating the existence of two different transition mechanisms: Zeeman splitting of Shiba states or gap closure due to Zeeman splitting of Bogoliubov states. We also study how in the presence of spin-orbit coupling, modeled as an additional noncollinear component of the magnetic field at the impurity site, the Shiba resonance overlapping with the quasiparticle continuum of the opposite spin gradually broadens and then merges with the continuum.

  7. Sputtering of a silicon surface: Preferential sputtering of surface impurities

    Energy Technology Data Exchange (ETDEWEB)

    Nietiadi, Maureen L. [Physics Department and Research Center OPTIMAS, University Kaiserslautern, Erwin-Schrödinger-Straße, D-67663 Kaiserslautern (Germany); Rosandi, Yudi [Physics Department and Research Center OPTIMAS, University Kaiserslautern, Erwin-Schrödinger-Straße, D-67663 Kaiserslautern (Germany); Department of Physics, Universitas Padjadjaran, Jatinangor, Sumedang 45363 (Indonesia); Lorinčík, Jan [Faculty of Science, J. E. Purkinje University, České mládeže 8, 400 96 Ústí nad Labem (Czech Republic); Institute of Photonics and Electronics, Academy of Sciences of the Czech Republic, Chaberská 57, 182 51 Praha (Czech Republic); Urbassek, Herbert M., E-mail: urbassek@rhrk.uni-kl.de [Physics Department and Research Center OPTIMAS, University Kaiserslautern, Erwin-Schrödinger-Straße, D-67663 Kaiserslautern (Germany)

    2013-05-15

    We present molecular-dynamics simulations of the sputtering of an impurity atom off a Si 2×1 (100) surface by 2 keV Ar ions. The impurity is characterized by its mass and its binding energy to the Si substrate. We find that sputtering strongly decreases with the mass and even more strongly with the binding energy of the impurity atom to the matrix. The velocity of the impurity perpendicular to the surface is reduced with increasing impurity mass and binding energy. In terms of available ionization theories we can conclude that heavier impurities will have a smaller ionization probability.

  8. Correlations between locked modes and impurity influxes

    Energy Technology Data Exchange (ETDEWEB)

    Fishpool, G.M. [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Lawson, K.D. [UKAEA Culham Lab., Abingdon (United Kingdom)

    1994-07-01

    An analysis of pulses that were disturbed by medium Z impurity influxes (Cl, Cr, Fe and Ni) recorded during the 91/92 JET operations, has demonstrated that such influxes can result in MHD modes which subsequently ``lock``. A correlation is found between the power radiated by the influx and the time difference between the start of the influx and the beginning of the locked mode. The growth in the amplitude of the locked mode itself can lead to further impurity influxes. A correlation is noted between intense influxes (superior to 10 MW) and the mode ``unlocking``. (authors). 4 refs., 4 figs.

  9. Novel Bound States in Graphene with Impurities

    CERN Document Server

    Gupta, Kumar S

    2008-01-01

    We obtain a novel bound state spectrum of the low energy excitations near the Fermi points of graphene in the presence of a charge impurity. The effects of possible short range interactions induced by the impurity are modelled by suitable boundary conditions. The spectrum in the subcritical region of the effective Coulomb coupling is labelled by a parameter which characterizes the boundary conditions and determines the inequivalent quantizations of the system. In the supercritical region we obtain a renormalization group flow for the effective Coulomb coupling.

  10. The electronic structure of impurities in semiconductors

    CERN Multimedia

    Nylandsted larsen, A; Svane, A

    2002-01-01

    The electronic structure of isolated substitutional or interstitial impurities in group IV, IV-IV, and III-V compound semiconductors will be studied. Mössbauer spectroscopy will be used to investigate the incorporation of the implanted isotopes on the proper lattice sites. The data can be directly compared to theoretical calculations using the LMTO scheme. Deep level transient spectroscopy will be used to identify the band gap levels introduced by metallic impurities, mainly in Si~and~Si$ _{x}$Ge$_{1-x}$. \\\\ \\\\

  11. Identification, Characterization, and Quantification of Impurities of Safinamide Mesilate: Process-Related Impurities and Degradation Products.

    Science.gov (United States)

    Zou, Liang; Sun, Lili; Zhang, Hui; Hui, Wenkai; Zou, Qiaogen; Zhu, Zheying

    2017-07-01

    The characterization of process-related impurities and degradation products of safinamide mesilate (SAFM) in bulk drug and a stability-indicating HPLC method for the separation and quantification of all the impurities were investigated. Four process-related impurities (Imp-B, Imp-C, Imp-D, and Imp-E) were found in the SAFM bulk drug. Five degradation products (Imp-A, Imp-C, Imp-D, Imp-E, and Imp-F) were observed in SAFM under oxidative conditions. Imp-C, Imp-D, and Imp-E were also degradation products and process-related impurities. Remarkably, one new compound, identified as (S)-2-[4-(3-fluoro-benzyloxy) benzamido] propanamide (i.e., Imp-D), is being reported here as an impurity for the first time. Furthermore, the structures of the aforementioned impurities were characterized and confirmed via IR, NMR, and MS techniques, and the most probable formation mechanisms of all impurities proposed according to the synthesis route. Optimum separation was achieved on an Inertsil ODS-3 column (250 × 4.6 mm, 5 μm), using 0.1% formic acid in water (pH adjusted to 5.0) and acetonitrile as the mobile phase in gradient mode. The proposed method was found to be stability-indicating, precise, linear, accurate, sensitive, and robust for the quantitation of SAFM and its process-related substances, including its degradation products.

  12. Validation of gyrokinetic modelling of light impurity transport including rotation in ASDEX Upgrade

    CERN Document Server

    Casson, F J; Angioni, C; Camenen, Y; Dux, R; Fable, E; Fischer, R; Geiger, B; Manas, P; Menchero, L; Tardini, G

    2013-01-01

    Upgraded spectroscopic hardware and an improved impurity concentration calculation allow accurate determination of boron density in the ASDEX Upgrade tokamak. A database of boron measurements is compared to quasilinear and nonlinear gyrokinetic simulations including Coriolis and centrifugal rotational effects over a range of H-mode plasma regimes. The peaking of the measured boron profiles shows a strong anti-correlation with the plasma rotation gradient, via a relationship explained and reproduced by the theory. It is demonstrated that the rotodiffusive impurity flux driven by the rotation gradient is required for the modelling to reproduce the hollow boron profiles at higher rotation gradients. The nonlinear simulations validate the quasilinear approach, and, with the addition of perpendicular flow shear, demonstrate that each symmetry breaking mechanism that causes momentum transport also couples to rotodiffusion. At lower rotation gradients, the parallel compressive convection is required to match the mos...

  13. Electrostatic potential variation on the flux surface and its impact on impurity transport

    CERN Document Server

    García-Regaña, J M; Turkin, Y; Kleiber, R; Helander, P; Maaßberg, H; Alonso, J A; Velasco, J L

    2015-01-01

    The particle transport of impurities in magnetically confined plasmas under some conditions does not find, neither quantitatively nor qualitatively, a satisfactory theory-based explanation. This compromise the successful realization of thermo-nuclear fusion for energy production since its accumulation is known to be one of the causes that leads to the plasma breakdown. In standard reactor-relevant conditions this accumulation is in most stellarators intrinsic to the lack of toroidal symmetry, that leads to the neoclassical electric field to point radially inwards. This statement, that the standard theory allows to formulate, has been contradicted by some experiments that showed weaker or no accumulation under such conditions \\cite{Ida_pop_16_056111_2009, Yoshinuma_nf_49_062002_2009}. The charge state of the impurities makes its transport more sensitive to the electric fields. Thus, the short length scale turbulent electrostatic potential or its long wave-length variation on the flux surface $\\Phi_{1}$ -- that...

  14. Impurity Flow Measurements in DIII-D using Coherence Imaging Spectroscopy

    Science.gov (United States)

    Allen, S. L.; Meier, E. T.; Weber, T. R.; Hill, D. N.; Meyer, W. H.; Porter, G. D.; Howard, J.

    2012-10-01

    Imaging interferometers have been used to measure the 2-D distribution of the Doppler shift of impurity emission in both the lower and upper DIII-D divertors. The interferometer design has been simplified to a single birefringent plate between two polarizers, and improved calibration techniques have been implemented, including temperature stabilization. Measurements of other impurity species such as CII have been added. An image-intensified camera in the upper divertor has enabled measurement of the flows in the crown of the plasma during lower single-null divertor operation. In general, flows are in opposite directions on the inner and outer scrape-off layers in the divertor, as expected from the magnetic geometry. Initial results from a wide view periscope of the whole plasma cross section will also be presented.

  15. Potential metal impurities in active pharmaceutical substances and finished medicinal products - A market surveillance study.

    Science.gov (United States)

    Wollein, Uwe; Bauer, Bettina; Habernegg, Renate; Schramek, Nicholas

    2015-09-18

    A market surveillance study has been established by using different atomic spectrometric methods for the determination of selected elemental impurities of particular interest, to gain an overview about the quality of presently marketed drug products and their bulk drug substances. The limit tests were carried out with respect to the existing EMA guideline on the specification limits for residuals of metal catalysts or metal reagents. Also attention was given to the future implementation of two new chapters of the United States Pharmacopoeia (USP) stating limit concentrations of elemental impurities. The methods used for determination of metal residues were inductively coupled plasma-mass spectrometry (ICP-MS), inductively coupled plasma-optical emission spectrometry (ICP-OES), and atomic absorption spectrometry technologies (GFAAS, CVAAS, HGAAS). This article presents the development and validation of the methods used for the determination of 21 selected metals in 113 samples from drug products and their active pharmaceutical ingredients.

  16. Soft X-ray tomography in support of impurity control in tokamaks

    Science.gov (United States)

    Mlynar, J.; Mazon, D.; Imrisek, M.; Loffelmann, V.; Malard, P.; Odstrcil, T.; Tomes, M.; Vezinet, D.; Weinzettl, V.

    2016-10-01

    This contribution reviews an important example of current developments in diagnostic systems and data analysis tools aimed at improved understanding and control of transport processes in magnetically confined high temperature plasmas. The choice of tungsten for the plasma facing components of ITER and probably also DEMO means that impurity control in fusion plasmas is now a crucial challenge. Soft X-ray (SXR) diagnostic systems serve as a key sensor for experimental studies of plasma impurity transport with a clear prospective of its control via actuators based mainly on plasma heating systems. The SXR diagnostic systems typically feature high temporal resolution but limited spatial resolution due to access restrictions. In order to reconstruct the spatial distribution of the SXR radiation from line integrated measurements, appropriate tomographic methods have been developed and validated, while novel numerical methods relevant for real-time control have been proposed. Furthermore, in order to identify the main contributors to the SXR plasma radiation, at least partial control over the spectral sensitivity range of the detectors would be beneficial, which motivates for developments of novel SXR diagnostic methods. Last, but not least, semiconductor photosensitive elements cannot survive in harsh conditions of future fusion reactors due to radiation damage, which calls for development of radiation hard SXR detectors. Present research in this field is exemplified on recent results from tokamaks COMPASS, TORE SUPRA and the Joint European Torus JET. Further planning is outlined.

  17. Development of Impurity Profiling Methods Using Modern Analytical Techniques.

    Science.gov (United States)

    Ramachandra, Bondigalla

    2017-01-02

    This review gives a brief introduction about the process- and product-related impurities and emphasizes on the development of novel analytical methods for their determination. It describes the application of modern analytical techniques, particularly the ultra-performance liquid chromatography (UPLC), liquid chromatography-mass spectrometry (LC-MS), high-resolution mass spectrometry (HRMS), gas chromatography-mass spectrometry (GC-MS) and high-performance thin layer chromatography (HPTLC). In addition to that, the application of nuclear magnetic resonance (NMR) spectroscopy was also discussed for the characterization of impurities and degradation products. The significance of the quality, efficacy and safety of drug substances/products, including the source of impurities, kinds of impurities, adverse effects by the presence of impurities, quality control of impurities, necessity for the development of impurity profiling methods, identification of impurities and regulatory aspects has been discussed. Other important aspects that have been discussed are forced degradation studies and the development of stability indicating assay methods.

  18. The Potts model on a Bethe lattice with nonmagnetic impurities

    Energy Technology Data Exchange (ETDEWEB)

    Semkin, S. V., E-mail: li15@rambler.ru; Smagin, V. P. [Vladivistok State University of Economics and Service (VSUES) (Russian Federation)

    2015-10-15

    We have obtained a solution for the Potts model on a Bethe lattice with mobile nonmagnetic impurities. A method is proposed for constructing a “pseudochaotic” impurity distribution by a vanishing correlation in the arrangement of impurity atoms for the nearest sites. For a pseudochaotic impurity distribution, we obtained the phase-transition temperature, magnetization, and spontaneous magnetization jumps at the phase-transition temperature.

  19. EMC3-EIRENE modelling of edge impurity transport in the stochastic layer of the large helical device compared with extreme ultraviolet emission measurements

    Science.gov (United States)

    Dai, Shuyu; Kobayashi, M.; Kawamura, G.; Morita, S.; Zhang, H. M.; Oishi, T.; Feng, Y.; Wang, D. Z.; Suzuki, Y.; the LHD Experimental Group

    2016-06-01

    The transport properties and line emissions of carbon impurity in the stochastic layer of the Large Helical Device have been investigated with the 3D edge transport code EMC3-EIRENE. A parameter study has been performed to examine the sensitivity of the simulation results on each transport term in the impurity transport model and the impurity source characteristics, i.e. the source amount and the location. The modelling has revealed that in order to reproduce the experimental results of the emission distribution, the impurity perpendicular transport coefficient (D imp) and the first wall source play important roles, while changes to the ion thermal and the friction forces are rather irrelevant. The detailed study of flux tube tracing and magnetic field structure in the edge stochastic layer, in relation to impurity transport, has shown that the deeper penetration of impurity into the higher plasma density region due to the enhanced D imp and the first wall source is responsible for the change of emission pattern as well as the intensity. The analysis indicates that D imp might be larger than that of background plasma by a few factors and also that there probably exists a substantial amount of first wall impurity source.

  20. Monte Carlo method for magnetic impurities in metals

    Science.gov (United States)

    Hirsch, J. E.; Fye, R. M.

    1986-01-01

    The paper discusses a Monte Carlo algorithm to study properties of dilute magnetic alloys; the method can treat a small number of magnetic impurities interacting wiith the conduction electrons in a metal. Results for the susceptibility of a single Anderson impurity in the symmetric case show the expected universal behavior at low temperatures. Some results for two Anderson impurities are also discussed.

  1. Metal-based impurities in graphenes: application for electroanalysis.

    Science.gov (United States)

    Chee, Sze Yin; Pumera, Martin

    2012-05-01

    We show here that metallic impurities presented in graphenes prepared from graphite can be usefully employed for electroanalysis. We demonstrate that cumene hydroperoxide electrochemical reduction on graphene containing iron-based impurities provides significantly larger voltammetric currents than the same experiment using iron oxide nanoparticles. This opens doors for turning metallic impurities into potentially useful components of graphene based electrochemical systems.

  2. Tuning oxygen impurities and microstructure of nanocrystalline silicon photovoltaic materials through hydrogen dilution.

    Science.gov (United States)

    Wen, Chao; Xu, Hao; He, Wei; Li, Zhengping; Shen, Wenzhong

    2014-01-01

    As a great promising material for third-generation thin-film photovoltaic cells, hydrogenated nanocrystalline silicon (nc-Si:H) thin films have a complex mixed-phase structure, which determines its defectful nature and easy residing of oxygen impurities. We have performed a detailed investigation on the microstructure properties and oxygen impurities in the nc-Si:H thin films prepared under different hydrogen dilution ratio treatment by the plasma-enhanced chemical vapor deposition (PECVD) process. X-ray diffraction, transmission electron microscopy, Raman spectroscopy, and optical transmission spectroscopy have been utilized to fully characterize the microstructure properties of the nc-Si:H films. The oxygen and hydrogen contents have been obtained from infrared absorption spectroscopy. And the configuration state of oxygen impurities on the surface of the films has been confirmed by X-ray photoelectron spectroscopy, indicating that the films were well oxidized in the form of SiO2. The correlation between the hydrogen content and the volume fraction of grain boundaries derived from the Raman measurements shows that the majority of the incorporated hydrogen is localized inside the grain boundaries. Furthermore, with the detailed information on the bonding configurations acquired from the infrared absorption spectroscopy, a full explanation has been provided for the mechanism of the varying microstructure evolution and oxygen impurities based on the two models of ion bombardment effect and hydrogen-induced annealing effect.

  3. Atomic and molecular processes in fusion plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Janev, R.K. [International Atomic Energy Agency, Vienna (Austria)

    1997-01-01

    The role of atomic and molecular processes in achieving and maintaining the conditions for thermonuclear burn in a magnetically confined fusion plasma is described. Emphasis is given to the energy balance and power and particle exhaust issues. The most important atomic and molecular processes which affect the radiation losses and impurity transport in the core plasma, the neutral particle transport in the plasma edge and the radiative cooling of divertor plasmas are discussed in greater detail. (author)

  4. Impurity diffusion in a harmonic potential and nonhomogeneous temperature

    Science.gov (United States)

    Aragie, Berhanu; Asfaw, Mesfin; Demeyu, Lemi; Bekele, Mulugeta

    2014-09-01

    We propose different ways of manipulating the dispersion of impurities along a semiconductor layer during heat treatment. The impurities undergo a random walk assisted by a nonlinear harmonic potential and nonhomogeneous temperature. Depending on the strength of a hot spot, trap potential, impurity density and standard deviation of the hot spot, the impurities diffuse away from the central region and pile up around the peripheral region of the semiconductor layer. Furthermore, the numerical result depicts that the internal field at high doping level can be of sufficient strength to cause the broadening of the impurity profile.

  5. Investigations on the heat flux and impurity for the HL-2M divertor

    Science.gov (United States)

    Zheng, G. Y.; Cai, L. Z.; Duan, X. R.; Xu, X. Q.; Ryutov, D. D.; Cai, L. J.; Liu, X.; Li, J. X.; Pan, Y. D.

    2016-12-01

    The controllability of the heat load and impurity in the divertor is very important, which could be one of the critical problems to be solved in order to ensure the success for a steady state tokamak. HL-2M has the advantage of the poloidal field (PF) coils placed inside the demountable toroidal field (TF) coils and close to the main plasma. As a result, it is possible to make highly accurate configuration control of the advanced divertor for HL-2M. The divertor target geometry of HL-2M has been designed to be compatible with different divertor configurations to study the divertor physics and support the high performance plasma operations. In this paper, the heat loads and impurities with different divertor configurations, including the standard X-point divertor, the snowflake-minus divertor and two tripod divertor configurations for HL-2M, are investigated by numerical simulations with the SOLPS5.0 code under the current design of the HL-2M divertor geometry. The plasmas with different conditions, such as the low discharge parameters with {{I}\\text{p}}   =  0.5 MA at the first stage of HL-2M and the high parameters with {{I}\\text{p}}   =  2.0 MA during the normal operations, are simulated. The heat load profiles and the impurity distributions are obtained, and the control of the peak heat load and the effect of impurity on the core plasma are discussed. The compatibility of different divertor configurations for HL-2M is also evaluated. It is seen that the excellent compatibility of different divertor configurations with the current divertor geometry has been verified. The results show that the snowflake-minus divertor and the tripod divertor with {{d}x}=30 \\text{cm} present good performance in terms of the heat load profiles and the impurity distributions under different conditions, which may not have a big effect on the core plasma. In addition, it is possible to optimize the distance between the two X-points, {{d}x} , to achieve a better

  6. Bound States in Boson Impurity Models

    Science.gov (United States)

    Shi, Tao; Wu, Ying-Hai; González-Tudela, A.; Cirac, J. I.

    2016-04-01

    The formation of bound states involving multiple particles underlies many interesting quantum physical phenomena, such as Efimov physics or superconductivity. In this work, we show the existence of an infinite number of such states for some boson impurity models. They describe free bosons coupled to an impurity and include some of the most representative models in quantum optics. We also propose a family of wave functions to describe the bound states and verify that it accurately characterizes all parameter regimes by comparing its predictions with exact numerical calculations for a one-dimensional tight-binding Hamiltonian. For that model, we also analyze the nature of the bound states by studying the scaling relations of physical quantities, such as the ground-state energy and localization length, and find a nonanalytical behavior as a function of the coupling strength. Finally, we discuss how to test our theoretical predictions in experimental platforms, such as photonic crystal structures and cold atoms in optical lattices.

  7. Extrinsic germanium Blocked Impurity Bank (BIB) detectors

    Science.gov (United States)

    Krabach, Timothy N.; Huffman, James E.; Watson, Dan M.

    1989-01-01

    Ge:Ga blocked-impurity-band (BIB) detectors with long wavelength thresholds greater than 190 microns and peak quantum efficiencies of 4 percent, at an operating temperature of 1.8 K, have been fabricated. These proof of concept devices consist of a high purity germanium blocking layer epitaxially grown on a Ga-doped Ge substrate. This demonstration of BIB behavior in germanium enables the development of far infrared detector arrays similar to the current silicon-based devices. Present efforts are focussed on improving the chemical vapor deposition process used to create the blocking layer and on the lithographic processing required to produce monolithic detector arrays in germanium. Approaches to test the impurity levels in both the blocking and active layers are considered.

  8. Turbulent transport of impurities and their effect on energy confinement

    CERN Document Server

    Pusztai, I; Fulop, T; Candy, J

    2012-01-01

    By presenting linear and nonlinear gyrokinetic similarity studies, based on a balanced neutral beam injection deuterium discharge from the DIII-D tokamak, we demonstrate that impurities alter the scaling of the transport on the charge and mass of the main species, and even more importantly, they can dramatically change the energy transport even in relatively small quantities. A poloidally varying equilibrium electrostatic potential can lead to a strong reduction or sign change of the impurity peaking factor due to the combined effect of the in-out impurity density asymmetry and the EXB drift of impurities. We present an approximate expression for the impurity peaking factor and demonstrate that impurity peaking is not significantly affected by impurity self-collisions.

  9. Quantum Entanglement in the Two Impurity Kondo Model

    CERN Document Server

    Cho, S Y; Cho, Sam Young; Kenzie, Ross H. Mc

    2005-01-01

    In order to quantify quantum entanglement in two impurity Kondo systems, we calculate the concurrence, negativity, and von Neumann entropy. The entanglement of the two Kondo impurities is shown to be determined by two competing many-body effects, the Kondo effect and the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction, $I$. Due to the spin-rotational invariance of the ground state, the concurrence and negativity are uniquely determined by the spin-spin correlation between the impurities. It is found that there exists a critical minimum value of the antiferromagnetic correlation between the impurity spins which is necessary for entanglement of the two impurity spins. The critical value is discussed in relation with the unstable fixed point in the two impurity Kondo problem. Specifically, at the fixed point there is no entanglement between the impurity spins. Entanglement will only be created (and quantum information processing (QIP) be possible) if the RKKY interaction exchange energy, $I$, is at least severa...

  10. Effect of impurities and processing on silicon solar cells. Volume 1: Characterization methods for impurities in silicon and impurity effects data base

    Science.gov (United States)

    Hopkins, R. H.; Davis, J. R.; Rohatgi, A.; Campbell, R. B.; Blais, P. D.; Rai-Choudhury, P.; Stapleton, R. E.; Mollenkopf, H. C.; Mccormick, J. R.

    1980-01-01

    Two major topics are treated: methods to measure and evaluate impurity effects in silicon and comprehensive tabulations of data derived during the study. Discussions of deep level spectroscopy, detailed dark I-V measurements, recombination lifetime determination, scanned laser photo-response, conventional solar cell I-V techniques, and descriptions of silicon chemical analysis are presented and discussed. The tabulated data include lists of impurity segregation coefficients, ingot impurity analyses and estimated concentrations, typical deep level impurity spectra, photoconductive and open circuit decay lifetimes for individual metal-doped ingots, and a complete tabulation of the cell I-V characteristics of nearly 200 ingots.

  11. Edge and divertor plasma: detachment, stability, and plasma-wall interactions

    Science.gov (United States)

    Krasheninnikov, S. I.; Kukushkin, A. S.; Lee, Wonjae; Phsenov, A. A.; Smirnov, R. D.; Smolyakov, A. I.; Stepanenko, A. A.; Zhang, Yanzeng

    2017-10-01

    The paper presents an overview of the results of studies on a wide range of the edge plasma related issues. The rollover of the plasma flux to the target during progressing detachment process is shown to be caused by the increase of the impurity radiation loss and volumetric plasma recombination, whereas the ion-neutral friction, although important for establishing the necessary edge plasma conditions, does not contribute per se to the rollover of the plasma flux to the target. The processes limiting the power loss by impurity radiation are discussed and a simple estimate of this limit is obtained. Different mechanisms of meso-scale thermal instabilities driven by impurity radiation and resulting in self-sustained oscillations in the edge plasma are identified. An impact of sheared magnetic field on the dynamics of the blobs and ELM filaments playing an important role in the edge and SOL plasma transport is discussed. Trapping of He, which is an intrinsic impurity for the fusion plasmas, in the plasma-facing tungsten material is considered. A newly developed model, accounting for the generation of additional He traps caused by He bubble growth, fits all the available experimental data on the layer of nano-bubbles observed in W under irradiation by low energy He plasma.

  12. Gyrokinetic study of the impact of the electron to ion heating ratio on the turbulent diffusion of highly charged impurities

    Energy Technology Data Exchange (ETDEWEB)

    Angioni, C. [Max-Planck-Institut für Plasmaphysik, D-85748 Garching (Germany)

    2015-10-15

    A gyrokinetic study based on numerical and analytical calculations is presented, which computes the dependence of the turbulent diffusion of highly charged impurities on the ratio of the electron to the ion heat flux of the plasma. Nonlinear simulations show that the size of the turbulent diffusion of heavy impurities can vary by one order of magnitude with fixed total heat flux and is an extremely sensitive function of the electron to ion heat flux ratio. Numerical linear calculations are found to reproduce the nonlinear results. Thereby, a quasi-linear analytical approach is used to explain the origin of this dependence.

  13. Impurities: Curse and blessing for crystal growers

    Science.gov (United States)

    Fox, Donald K.; Mazelsky, R.

    1990-11-01

    The indespensability of high-quality source materials research and development has been established for many years. However, because contributors to this field are diverse and communication of research results is often fragmented, transfer of the new knowledge is very slow. This paper describes how increasing source purity has improved the quality of several crystals, and how the addition of controlled impurities has decreased the defect density in these crystals. Experimental evidence is presented in this paper.

  14. Removal of iron from impure graphites

    Energy Technology Data Exchange (ETDEWEB)

    Growcock, F.B.; Heiser, J.

    1979-01-01

    Iron-impregnated and ash-rich graphites have been purified by leaching with gaseous I/sub 2/ at 900/sup 0/C. With addition of H/sub 2/, the rate of removal of impurity iron can be markedly increased and becomes comparable to that obtained with Cl/sub 2/. I/sub 2/ has an advantage in that it can also volatilize Ca and perhaps Ba and Sr.

  15. Characteristics of impurity-induced pseudogap

    Energy Technology Data Exchange (ETDEWEB)

    Numata, Yoshinori, E-mail: yo_c.n-15@ruri.waseda.jp; Uto, Tatsuro; Matuda, Azusa

    2016-05-15

    Highlights: • We have studied characteristics of the pseudogap states of Co substituted Bi2212 crystals used by STM/STS. • The pseudogap of Co 4% samples have temperature dependence. • We observed a disappearance of a 4a periodic modulation and a development of 1D modulation in the DOS. • An intimate relation between the DOS modulation and the pseudogap is confirmed. - Abstract: We have performed STM/STS measurements on a single crystal of Bi{sub 2.1}Sr{sub 1.9}Ca (Cu{sub 1−x}Co{sub x}) {sub 2}O{sub 8+δ} (Co-Bi2212), to reveal impurity effects on the pseudogap in cuprate high-T{sub c} superconductors. We report a drastic change in the temperature dependence of a pseudogap and in the density of states (DOS) modulation with a 4a period, in a certain doping range. In the Co 4% substituted samples, the pseudogap gradually closed like a gap of a BCS superconductor for slightly overdoped and overdoped regime, while their low temperature values were enhanced due to impurity. In addition, a disappearance of a 4a periodic modulation and a development of new modulation were observed in the DOS spatial distribution. These results indicate an intimate relation between the DOS modulation and the pseudogap, and qualitative difference in the impurity enhanced pseudogap and conventional one.

  16. Electrophobic interaction induced impurity clustering in metals

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Hong-Bo; Wang, Jin-Long; Jiang, W.; Lu, Guang-Hong; Aguiar, J. A.; Liu, Feng

    2016-10-01

    We introduce the concept of electrophobic interaction, analogous to hydrophobic interaction, for describing the behavior of impurity atoms in a metal, a 'solvent of electrons'. We demonstrate that there exists a form of electrophobic interaction between impurities with closed electron shell structure, which governs their dissolution behavior in a metal. Using He, Be and Ar as examples, we predict by first-principles calculations that the electrophobic interaction drives He, Be or Ar to form a close-packed cluster with a clustering energy that follows a universal power-law scaling with the number of atoms (N) dissolved in a free electron gas, as well as W or Al lattice, as Ec is proportional to (N2/3-N). This new concept unifies the explanation for a series of experimental observations of close-packed inert-gas bubble formation in metals, and significantly advances our fundamental understanding and capacity to predict the solute behavior of impurities in metals, a useful contribution to be considered in future material design of metals for nuclear, metallurgical, and energy applications.

  17. Table-top pellet injector (TATOP) for impurity pellet injection

    Energy Technology Data Exchange (ETDEWEB)

    Szepesi, Tamás, E-mail: szepesi.tamas@wigner.mta.hu [Wigner RCP, RMI, Konkoly Thege 29-33, H-1121 Budapest (Hungary); Herrmann, Albrecht [Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany); Kocsis, Gábor; Kovács, Ádám; Németh, József [Wigner RCP, RMI, Konkoly Thege 29-33, H-1121 Budapest (Hungary); Ploeckl, Bernhard [Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching (Germany)

    2015-10-15

    Highlights: • A portable pellet injector for solid state pellets was designed. • Aims to study ELM triggering potential of impurity pellets. • Aims for multi-machine comparison of pellet–plasma interaction. • Max. pellet speed: 450 m/s, max. rate: 25 Hz. • Pellet size: 0.5–1.5 mm (diameter). - Abstract: A table-top pellet injector (TATOP) has been designed to fulfill the following scientific aims: to study the ELM triggering potential of impurity pellets, and to make pellet injection experiments comparable over several fusion machines. The TATOP is based on a centrifugal accelerator therefore the complete system is run in vacuum, ensuring the compatibility with fusion devices. The injector is able to launch any solid material (stable at room temperature) in form of balls with a diameter in the 0.5–1.5 mm range. The device hosts three individual pellet tanks that can contain e.g. pellets of different materials, and the user can select from those without opening the vacuum chamber. A key element of the accelerator is a two-stage stop cylinder that reduces the spatial scatter of pellets exiting the acceleration arm below 6°, enabling the efficient collection of all fired pellets. The injector has a maximum launch speed of 450 m/s. The launching of pellets can be done individually by providing TTL triggers for the injector, giving a high level of freedom for the experimenter when designing pellet trains. However, the (temporary) firing rate cannot be larger than 25 Hz. TATOP characterization was done in a test bed; however, the project is still in progress and before application at a fusion oriented experiment.

  18. Motion of a Distinguishable Impurity in the Bose Gas: Arrested Expansion Without a Lattice and Impurity Snaking

    Science.gov (United States)

    Robinson, Neil J.; Caux, Jean-Sébastien; Konik, Robert M.

    2016-04-01

    We consider the real-time dynamics of an initially localized distinguishable impurity injected into the ground state of the Lieb-Liniger model. Focusing on the case where integrability is preserved, we numerically compute the time evolution of the impurity density operator in regimes far from analytically tractable limits. We find that the injected impurity undergoes a stuttering motion as it moves and expands. For an initially stationary impurity, the interaction-driven formation of a quasibound state with a hole in the background gas leads to arrested expansion—a period of quasistationary behavior. When the impurity is injected with a finite center-of-mass momentum, the impurity moves through the background gas in a snaking manner, arising from a quantum Newton's cradlelike scenario where momentum is exchanged back and forth between the impurity and the background gas.

  19. Density of states of the one-dimensional electron gas: Impurity levels, impurity bands, and the band tail

    Science.gov (United States)

    Gold, A.; Ghazali, A.

    1994-06-01

    The density of states of cylindrical quantum wires is calculated in the presence of charged impurities located in the center of the wire. A multiple-scattering approach (Klauder's fifth approximation), which represents a self-consistent t-matrix approximation, is used. For small impurity densities and in the weak screening limit the ground-state impurity band and four excited-state impurity bands are obtained within our approach. We find good agreement between the numerically obtained spectral densities with the corresponding analytical spectral densities calculated with the single-impurity wave functions. The merging of impurity bands is studied. For large impurity densities we obtain a band tail. We present an analytical expression for the disorder-induced renormalized band-edge energy in the band-tail regime.

  20. Plasma chemistry study of PLAD processes

    Energy Technology Data Exchange (ETDEWEB)

    Qin Shu; Brumfield, Kyle; Liu, Lequn Jennifer; Hu, Yongjun Jeff; McTeer, Allen; Hsu, Wei Hui; Wang Maoying [Nanya Technology Inc., Santa Clara, CA 95054 (United States); Micron Technology Inc., Boise, ID 83707 (United States)

    2012-11-06

    Plasma doping (PLAD) shows very different impurity profiles compared to the conventional beam-line-based ion implantations due to its non-mass separation property and plasma environment. There is no simulation for PLAD process so far due to a lack of a dopant profile model. Several factors determine impurity profiles of PLAD process. The most significant factors are: plasma chemistry and deposition/etching characteristics of multi-ion species plasmas. In this paper, we present plasma chemistry and deposition/etching characteristics of PLAD processes versus co-gas dilutions. Four dopant plasmas including B{sub 2}H{sub 6}, BF{sub 3}, AsH{sub 3}, and PH{sub 3}, and two non-dopant plasmas including CH{sub 4} and GeH{sub 4} are studied and demonstrated.

  1. Utilizing solid impurity granules for ELM pacing in NSTX-U

    Science.gov (United States)

    Lunsford, Robert; Roquemore, L.; Jaworski, M. A.; Kaita, R.; Maingi, R.; NSTX-U Team

    2015-11-01

    Periodic edge localized modes (ELMs) rapidly transport stored energy from the edge plasma to the divertor. These events result in abrupt heating of the plasma facing components (PFCs) which reduces their effective lifetime as well as generating a strong impurity influx. If the frequency of these ELMs can be increased through controlled triggering, also known as pacing, then the inverse relationship between the peak heat flux and the frequency of the ELMs can be utilized to prevent material damage that could result from otherwise unmitigated ELMs. At NSTX, the ability of small (300 - 1000 micron) impurity granules to trigger and pace these ELMs is being explored. In these experiments, ELMs are triggered by seeding a density perturbation within the edge-pedestal region through low speed injection and ablation of impurity granules, thus generating a localized instability. Granules are dropped from a reservoir and transit a vertical flight tube at which point a rotating impeller imparts horizontal momentum into the falling granules. This drives them into the edge of the discharge at speeds ranging from 50-150 m/s and average injection frequencies of up to 200 Hz depending upon the settings of the injector. Results from the initial laboratory injection tests of lithium, boron carbide (B4C) and vitreous carbon granules and their subsequent implementation in NSTX-U experiments will be discussed. Work supported by DOE Contract No. DE-AC02-09CH11466.

  2. Structural Identification and Characterization of Potential Impurities of Azelnidipine

    Directory of Open Access Journals (Sweden)

    Sureshbabu Kapavarapu

    2016-06-01

    Full Text Available Azelnidipine (AZL is a pale yellowish white tablet (16mg with diameter of 9.2mm and thickness of 3.3mm. A reverse phase performance liquid chromatographic method was developed for the determination of AZL in bulk and pharmaceutical dosage form. During the synthesis of bulk drug of AZL, we observed four impurities. All the impurities were detected by a gradient high performance liquid chromatographic (HPLC method. LC-MS was performed to identify the mass number of these impurities. A thorough study was carried out to characterize the impurities. These impurities were synthesized, characterized and were co-injected with the sample containing impurities and are found to be matching with the impurities present in the sample. Based on the complete spectral analysis (UV, IR, NMR and MS these impurities were characterized as 1 Azelnidipine Stage-I para impurity [Impurity 1], whose molecular formula is C14 H15 NO5 and molecular weight is 277.27, 2 Azelnidipine Intermediate [Impurity 2], whose molecular formula is C14H15NO5 and molecular weight is 277.27, 3 4-Nitro Azelnidipine [Impurity 3], whose molecular formula is C33H34N4O6 and molecular weight is 582.65 and, 4 2-Nitro Azelnidipine [Impurity 4], whose molecular formula is C33H34N4O6 and molecular weight is 582.65. The proposed method was validated as per International Conference on Harmonization (ICH guidelines. The method was accurate, precise, specific and rapid found to be suitable for the quantitative analysis of the drug and dosage form.

  3. Influence of Impurities on the Radiation Response of the TlBr Semiconductor Crystal

    Directory of Open Access Journals (Sweden)

    Robinson Alves dos Santos

    2017-01-01

    Full Text Available Two commercially available TlBr salts were used as the raw material for crystal growths to be used as radiation detectors. Previously, TlBr salts were purified once, twice, and three times by the repeated Bridgman method. The purification efficiency was evaluated by inductively coupled plasma mass spectroscopy (ICP-MS, after each purification process. A compartmental model was proposed to fit the impurity concentration as a function of the repetition number of the Bridgman growths, as well as determine the segregation coefficients of impurities in the crystals. The crystalline structure, the stoichiometry, and the surface morphology of the crystals were evaluated, systematically, for the crystals grown with different purification numbers. To evaluate the crystal as a radiation semiconductor detector, measurements of its resistivity and gamma-ray spectroscopy were carried out, using 241Am and 133Ba sources. A significant improvement of the radiation response was observed in function of the crystal purity.

  4. The influence of neon or argon impurities on deuterium permeation in tungsten

    Energy Technology Data Exchange (ETDEWEB)

    Ishida, M., E-mail: ishida@st.eie.eng.osaka-u.ac.jp; Lee, H.T.; Ueda, Y.

    2015-08-15

    Nitrogen (N) or neon (Ne) in the divertor and argon (Ar) puffing in the first wall have been proposed to reduce the local power loads on tungsten (W) plasma facing components. The impurities sputter and modify the W surface, which can affect hydrogen (H, D, T) transport in W. In this study, mixed D + Ne or D + Ar ion driven permeation experiments were performed to investigate the influence of Ne or Ar impurities on D transport. The D permeation flux for mixed irradiation was lower in comparison to D-only irradiation at T > 500 K, opposite to trends observed for N. The reason for the observed decrease in permeation flux was interpreted to arise from combined effects of sputtering and possible precipitation. The lag times for D + Ne case was slower than D-only case, while D + Ar was faster. This indicates Ne precipitation effects may influence the H transport in W similar to helium.

  5. Profiling extractable and leachable inorganic impurities in ophthalmic drug containers by ICP-MS.

    Science.gov (United States)

    Solomon, Paige; Nelson, Jenny

    2017-08-24

    In this study, we investigated the elemental impurities present in the plastic material of ophthalmic eye drop bottles using inductively coupled plasma-mass spectrometry (ICP-MS). Metallic contaminations, especially localized within the small cavity of the eye, can significantly perturb the ocular metallome. The concern is two-fold: first certain elements, for example heavy metals, can be toxic to humans at even trace levels, and second, these contaminations can have adverse reactions with other medicines or enzymatic processes in the eye. The implication of redox-active metals in cataract formation is one such biological consequence. The analysis demonstrated the effect of aggressive storage and transportation conditions on elemental extractable and leachable contamination, and posits that release of these elemental impurities can disrupt metallome equilibrium in the ocular compartment, leading to toxicity and disease.

  6. Thermodynamics estimation of copper plasma efficiency from secondary raw material

    Directory of Open Access Journals (Sweden)

    Віктор Сергійович Козьмін

    2014-09-01

    Full Text Available The results of the thermodynamic evaluation of oxidative plasma copper refining efficiency recycled from impurities present in the feedstock are shown. It was established that the type of impurity factor increasing the efficiency of the plasma refining the potential change of Gibbs varies from 1,4 to 4, 8, and for silver, and of gold there is a transition from an unlikely to real positive state. 

  7. Modelling the influence of temperature anisotropies on poloidal asymmetries of density in the core of rotating plasmas

    Science.gov (United States)

    Bilato, R.; Maj, O.; Angioni, C.

    2014-07-01

    A consistent set of equations is derived to model poloidal density asymmetries induced by temperature anisotropies in tokamak rotating plasmas. The model can be applied to compute poloidal density asymmetry of highly charged impurities due to additional plasma heating.

  8. Impact of the neoclassical distribution function on turbulent impurity and momentum fluxes: fluid model and gyrokinetic simulations

    Science.gov (United States)

    Manas, P.; Hornsby, W. A.; Angioni, C.; Camenen, Y.; Peeters, A. G.

    2017-03-01

    The impact of the neoclassical background on turbulent impurity transport is investigated by means of gyrokinetic simulations supported by fluid equations. The latter are derived, using a Laguerre polynomials expansion of the first order neoclassical distribution function, and analytical expressions of the turbulent momentum flux and impurity transport coefficients are assessed. Comparisons of gyrokinetic simulations including this neoclassical background (coupling between the codes GKW and NEO) and the fluid model are used to identify the main mechanisms behind the modification of the turbulent transport channels and benchmark the numerical implementation. These mechanisms include a modification of the parallel dynamics of the main ions and direct contributions stemming from the asymmetry in the parallel velocity space of the neoclassical distribution function. The latter which is found dominant for turbulent impurity transport, increases with increasing collisionality, R/{L}{Ti}, R/{L}n, impurity mass, safety factor and aspect ratio. These contributions to momentum and impurity fluxes are also found to depend on the directions of the toroidal magnetic field and plasma current.

  9. Exact solution of a t-J chain with impurity

    Energy Technology Data Exchange (ETDEWEB)

    Beduerftig, G. [Hannover Univ. (Germany). Inst. fuer Theoretische Physik; Essler, F.H.L. [Oxford Univ. (United Kingdom). Dept. of Theoretical Physics; Frahm, H. [Hannover Univ. (Germany). Inst. fuer Theoretische Physik

    1997-04-07

    We study the effects of an integrable impurity in a periodic t-J chain. The impurity couples to both spin and charge degrees of freedom and has the interesting feature that the interaction with the bulk can be varied continuously without losing integrability. We first consider ground state properties close to half-filling in the presence of a small bulk magnetic field. We calculate the impurity contributions to the (zero-temperature) susceptibilities and the low-temperature specific heat and determine the high-temperature characteristics of the impurity. We then investigate transport properties by computing the spin and charge stiffnesses at zero temperature. Finally the impurity phase shifts are calculated and the existence of an impurity bound state in the holon sector is established. (orig.).

  10. Magnetic states of single impurity in disordered environment

    Directory of Open Access Journals (Sweden)

    G.W. Ponedilok

    2013-01-01

    Full Text Available The charged and magnetic states of isolated impurities dissolved in amorphous metallic alloy are investigated. The Hamiltonian of the system under study is the generalization of Anderson impurity model. Namely, the processes of elastic and non-elastic scattering of conductive electrons on the ions of a metal and on a charged impurity are included. The configuration averaged one-particle Green's functions are obtained within Hartree-Fock approximation. A system of self-consistent equations is given for calculation of an electronic spectrum, the charged and the spin-polarized impurity states. Qualitative analysis of the effect of the metallic host structural disorder on the observed values is performed. Additional shift and broadening of virtual impurity level is caused by a structural disorder of impurity environment.

  11. Impurity binding energy for -doped quantum well structures

    Indian Academy of Sciences (India)

    V Tulupenko; C A Duque; R Demediuk; O Fomina; V Akimov; V Belykh; T Dmitrichenko; V Poroshin

    2014-10-01

    The binding energy of an impurity delta layer situated either in the centre or at the edge of a quantum well (QW) is theoretically considered for the example of -type Si0.8Ge0.2/Si/Si0.8Ge0.2 QW doped with phosphorus. Calculations are made for the case of not so big impurity concentrations, when impurity bands are not yet formed and it is still possible to treat impurity as isolated ones. It is shown on the base of self-consistent solution of Schrödinger, Poisson and electro-neutrality equations that impurity binding energy is dependent on the degree of impurity ionization and the most noticeably for the case of edge-doped QWs.

  12. Transitions and excitations in a superfluid stream passing small impurities

    KAUST Repository

    Pinsker, Florian

    2014-05-08

    We analyze asymptotically and numerically the motion around a single impurity and a network of impurities inserted in a two-dimensional superfluid. The criticality for the breakdown of superfluidity is shown to occur when it becomes energetically favorable to create a doublet—the limiting case between a vortex pair and a rarefaction pulse on the surface of the impurity. Depending on the characteristics of the potential representing the impurity, different excitation scenarios are shown to exist for a single impurity as well as for a lattice of impurities. Depending on the lattice characteristics it is shown that several regimes are possible: dissipationless flow, excitations emitted by the lattice boundary, excitations created in the bulk, and the formation of large-scale structures.

  13. Some aspects of impurity trapping of muons

    CERN Document Server

    Karlsson, E

    1981-01-01

    Several aspects of muon trapping in metals have been studied during the last two years, but the situation is still far from clear. The precise nature of the traps as well as the mechanisms leading to trapping seem to require more detailed investigations than those carried out so far. This review contains therefore a certain number of ideas which should be regarded as working hypotheses rather than established facts or descriptions of positive muon behaviour. The author considers muons in FCC metals (Al:Mn and Cu), and impurity trapping in BCC metals (V, Nb, Ta, Fe). (21 refs).

  14. Germanium Blocked Impurity Band (BIB) detectors

    Science.gov (United States)

    Haller, E. E.; Baumann, H.; Beeman, J. W.; Hansen, W. L.; Luke, P. N.; Lutz, M.; Rossington, C. S.; Wu, I. C.

    1989-01-01

    Information is given in viewgraph form. The advantages of the Si blocked impurity band (BIB) detector invented by M. D. Petroff and M. G. Stabelbroek are noted: smaller detection volume leading to a reduction of cosmic ray interference, extended wavelength response because of dopant wavefunction overlap, and photoconductive gain of unity. It is argued that the stated advantages of Si BIB detectors should be realizable for Ge BIB detectors. Information is given on detector development, subtrate choice and preparation, wafer polising, epitaxy, characterization of epi layers, and preliminary Ge BIB detector test results.

  15. Experimental studies of collisional plasma shocks and plasma interpenetration via merging supersonic plasma jets

    Science.gov (United States)

    Hsu, S. C.; Moser, A. L.; Merritt, E. C.; Adams, C. S.

    2015-11-01

    Over the past 4 years on the Plasma Liner Experiment (PLX) at LANL, we have studied obliquely and head-on-merging supersonic plasma jets of an argon/impurity or hydrogen/impurity mixture. The jets are formed/launched by pulsed-power-driven railguns. In successive experimental campaigns, we characterized the (a) evolution of plasma parameters of a single plasma jet as it propagated up to ~ 1 m away from the railgun nozzle, (b) density profiles and 2D morphology of the stagnation layer and oblique shocks that formed between obliquely merging jets, and (c) collisionless interpenetration transitioning to collisional stagnation between head-on-merging jets. Key plasma diagnostics included a fast-framing CCD camera, an 8-chord visible interferometer, a survey spectrometer, and a photodiode array. This talk summarizes the primary results mentioned above, and highlights analyses of inferred post-shock temperatures based on observations of density gradients that we attribute to shock-layer thickness. We also briefly describe more recent PLX experiments on Rayleigh-Taylor-instability evolution with magnetic and viscous effects, and potential future collisionless shock experiments enabled by low-impurity, higher-velocity plasma jets formed by contoured-gap coaxial guns. Supported by DOE Fusion Energy Sciences and LANL LDRD.

  16. Electric Effect of Impurity in Square Quantum Wires

    Institute of Scientific and Technical Information of China (English)

    LI Kui-Hua; ZHANG Ying-Tao; LI You-Cheng

    2004-01-01

    @@ In the presence of an electric fidd perpendicular to the axes of the wire, the binding energy of shallow donor impurity in finite square quantum well wires is calculated. For different impurity positions and aspect ratios of the wires, we investigate the Stark shift of the 1s-like state energy of the impurity by expanding the wavefunction into a two-dimensional Fourier series and by using the variational scheme.

  17. Recommended methods for purification of solvents and tests for impurities

    CERN Document Server

    Coetzee, J F

    1982-01-01

    Recommended Methods for Purification of Solvents and Tests for Impurities is a compilation of recommended procedures for purification of solvents and tests for solvent impurities. Ten solvents are covered: acetonitrile, sulfolane, propylene carbonate, dimethyl sulfoxide, dimethylformamide, hexamethylphosphoramide, pyridine, ethylenediamine, N-methylacetamide, and N-methylpropionamide. This book is comprised of 12 chapters and opens with an introduction to general aspects of impurity effects. The rationale for the selection of solvent is explained, and the relative reactivities of solutes in di

  18. Interactions of Ultracold Impurity Particles with Bose-Einstein Condensates

    Science.gov (United States)

    2015-06-23

    AFRL-OSR-VA-TR-2015-0141 INTERACTIONS OF ULTRACOLD IMPURITY PARTICLES WITH BOSE- EINSTEIN CONDENSATES Georg Raithel UNIVERSITY OF MICHIGAN Final...SUBTITLE Interactions of ultracold impurity particles with Bose- Einstein Condensates 5a. CONTRACT NUMBER FA9550-10-1-0453 5b. GRANT NUMBER 5c...Interactions of ultracold impurity particles with Bose- Einstein Condensates Contract/Grant #: FA9550-10-1-0453 Reporting Period: 8/15/2010 to 2/14

  19. Renormalization-group calculation of excitation properties for impurity models

    Science.gov (United States)

    Yoshida, M.; Whitaker, M. A.; Oliveira, L. N.

    1990-05-01

    The renormalization-group method developed by Wilson to calculate thermodynamical properties of dilute magnetic alloys is generalized to allow the calculation of dynamical properties of many-body impurity Hamiltonians. As a simple illustration, the impurity spectral density for the resonant-level model (i.e., the U=0 Anderson model) is computed. As a second illustration, for the same model, the longitudinal relaxation rate for a nuclear spin coupled to the impurity is calculated as a function of temperature.

  20. Anomalous screening of quantum impurities by a neutral environment

    OpenAIRE

    Yakaboylu, Enderalp; Lemeshko, Mikhail

    2016-01-01

    It is a common knowledge that an effective interaction of a quantum impurity with an electromagnetic field can be screened by surrounding charge carriers, whether mobile or static. Here we demonstrate that very strong, `anomalous' screening can take place in the presence of a neutral, weakly-polarizable environment, due to an exchange of orbital angular momentum between the impurity and the bath. Furthermore, we show that it is possible to generalize all phenomena related to isolated impuriti...

  1. Fractal growth in impurity-controlled solidification in lipid monolayers

    DEFF Research Database (Denmark)

    Fogedby, Hans C.; Sørensen, Erik Schwartz; Mouritsen, Ole G.

    1987-01-01

    A simple two-dimensional microscopic model is proposed to describe solidifcation processes in systems with impurities which are miscible only in the fluid phase. Computer simulation of the model shows that the resulting solids are fractal over a wide range of impurity concentrations and impurity...... diffusional constants. A fractal-forming mechanism is suggested for impurity-controlled solidification which is consistent with recent experimental observations of fractal growth of solid phospholipid domains in monolayers. The Journal of Chemical Physics is copyrighted by The American Institute of Physics....

  2. Influence of impurities on the specific optical rotation of cefozopran.

    Science.gov (United States)

    Liu, Shu-Yu; Li, Ya-Ping; Hu, Chang-Qin

    2012-07-01

    The impurities of cefozopran hydrochloride are analyzed using high-performance liquid chromatography (HPLC) with UV absorbance and optical rotation (OR) detection. The results show that the impurities can affect the specific optical rotation of the cefozopran product. Due to the different composition of impurities, the Chinese cefozopran hydrochloride product has a specific optical rotation different from the Japanese product. The relationship between impurity limits and specific optical rotation of cefozopran hydrochloride is revealed. The results provide a scientific rationale for setting the limit of specific optical rotation of cefozopran hydrochloride.

  3. Observation of interactions between impurities and hydrodynamics solitons

    Institute of Scientific and Technical Information of China (English)

    L(U) Lei; CHEN Weizhong; ZHU Yifei; LIN Han

    2004-01-01

    We have experimentally investigated interactions between impurities and hydrodynamic solitons in a shallow water trough subject to vertical vibration. The impurities are minor convex and concave defects located on the bottom of the trough, slightly varying the water depth. The experiments show that a shallow impurity will attract breathers and kinks while a deep one will repel them. These observations are consistent with the theoretical prediction proposed in the continuous Frankel-Kontorova model with impurities and can also be explained in the view of energy absorption.

  4. Ground- and excited-state impurity bands in quantum wells

    Science.gov (United States)

    Ghazali, A.; Gold, A.; Serre, J.

    1989-02-01

    The density of states and the spectral density of electrons in quantum wells with charged impurities are calculated with use of a multiple-scattering method. The impurity-density-dependent broadening and the gradual merging of the ground (1s) and excited (2p+/-,2s) impurity levels into impurity bands are investigated. At low density the shapes of the 1s, 2p+/-, and 2s spectral densities are found to be in excellent agreement with the analytical results obtained for the ideal two-dimensional Coulomb problem.

  5. R-matrix calculations in support of impurity influx measurements

    Science.gov (United States)

    Ballance, C. P.

    2016-09-01

    The RMPS (R-Matrix with Pseudo-States) method has been used with great success in the calculation of the collisional data for light fusion-related elements such as helium, beryllium or neon, both in terms of electron-impact excitation and also ground, metastable, and excited state ionisation. However, more complex atomic species such as Molybdenum and Tungsten have been choosen as plasma-facing elements in several tokamak experiments such as NSTX-U. During plasma operation there is an inevitable degree of wall erosion and therefore the determination of this impurity-influx rate from vessel walls needs to be characterized. In terms of atomic physics, this erosion rate can be determined from an SXB ratio and spectroscopic measurements of emitted line radiation. The SXB ratio is generated using a combination of electron-impact ionisation, excitation and the underlying atomic structure transition probabilities. The groundstate of Mo I and Mo II being half-open d shell systems quickly give rise to 100s of levels, and therefore the resulting spectral lines from the neutral and singly ionised species provides a convoluted picture. Therefore, subject to the constraints of spectrometer used, theoretically we are able to survey our structure and collisional calculations and pro-actively suggest particular diagnostic lines. There have been previous R-matrix calculations in LS coupling used for modelling of Mo, with mixed results, however it is hoped that this project shall resolve those differences. A method shall be presented that we use to determine which lines are most beneficial for analysis. I will present current electron-impact excitation and ionisation results for both neutral and singly ionised molybdenum.

  6. Glycolic acid physical properties and impurities assessment

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D. P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Pickenheim, B. R. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bibler, N. E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Hay, M. S. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-06-08

    This document has been revised due to recent information that the glycolic acid used in Savannah River National Laboratory (SRNL) experiments contains both formaldehyde and methoxyacetic acid. These impurities were in the glycolic acid used in the testing included in this report and in subsequent testing using DuPont (now called Chemours) supplied Technical Grade 70 wt% glycolic acid. However, these impurities were not reported in earlier revisions. Additional data concerning the properties of glycolic acid have also been added to this report. The Defense Waste Processing Facility (DWPF) is planning to implement a nitric-glycolic acid flowsheets to increase attainment to meet closure commitment dates during Sludge Batch 9. In fiscal year 2009, SRNL was requested to determine the physical properties of formic and glycolic acid blends. Blends of formic acid in glycolic acid were prepared and their physical properties tested. Increasing amounts of glycolic acid led to increases in blend density, viscosity and surface tension as compared to the 90 wt% formic acid that is currently used at DWPF. These increases are small, however, and are not expected to present any difficulties in terms of processing. The effect of sulfur impurities in Technical Grade glycolic acid was studied for its impact on DWPF glass quality. While the glycolic acid specification allows for more sulfate than the current formic acid specification, the ultimate impact is expected to be on the order of 0.033 wt% sulfur in glass. Note that lower sulfur content glycolic acid could likely be procured at some increased cost if deemed necessary. A paper study on the effects of radiation on glycolic acid was performed. The analysis indicates that substitution of glycolic acid for formic acid would not increase the radiolytic production rate of H2 and cause an adverse effect in the Slurry Receipt and Adjustment Tank (SRAT) or Slurry Mix Evaporator (SME) process. It has been cited that glycolic acid

  7. Estimation of trace impurities in reactor-grade uranium using ICP-AES.

    Science.gov (United States)

    Malhotra, R K; Satyanarayana, K

    1999-10-01

    Estimation of impurities in reactor grade uranium is important from the point of view of neutron economy. For chemical separation, ion exchange and solvent extraction techniques have been employed although the latter is generally preferred. Amongst various extractants TBP (tri-n-butyl phosphate), TBP-TOPO (tri-n-octyl phosphine oxide), or TOPO only (in CCl(4), xylene, dodecane) is most often used. New reagents like Cyanex-923 (mixture of 4 tri-alkyl phosphine oxides)/TEHP (tri-ethylhexyl phosphoric acid) are also being used. This communication reports chemical separation of uranium by precipitation using 1,2-diaminocyclohexane NNN'N'-tetra acetic acid (CyDTA)/ammonium hydroxide in presence of 1,10-phenanthroline and estimation of impurities in the filtrate by ICP-AES. Quantitative separation of U, a high spectral interferent in plasma and recovery of impurities have been achieved. Recovery of Cd has been improved by using 1,10-phenanthroline. The method is accurate and precise, offering a relative standard deviation ranging from less than 4% (3.8% for Eu at the 10mug g(-1) level) to 12.9% (for Ce at the 2.5 mug g(-1) level) for all the elements studied.

  8. Impact of nitrogen doping on growth and hydrogen impurity incorporation of thick nanocrystalline diamond films

    Institute of Scientific and Technical Information of China (English)

    Gu Li-Ping; Tang Chun-Jiu; Jiang Xue-Fan; J.L.Pintob

    2011-01-01

    A much larger amount of bonded hydrogen was found in thick nanocrystalline diamond (NCD) films produced by only adding 0.24% N2 into 4% CH4/H2 plasma, as compared to the high quality transparent microcrystalline diamond (MCD) films, grown using the same growth parameters except for nitrogen. These experimental results clearly evidence that defect formation and impurity incorporation (for example, N and H) impeding diamond grain growth is the main formation mechanism of NCD upon nitrogen doping and strongly support the model proposed in the literature that nitrogen competes with CHX (x = 1,2,3) growth species for adsorption sites.

  9. Impurity Conductivity in Semiconductors Resulting from Radiant Excitation

    OpenAIRE

    TOULANOV, Vakhab T.; DAVLETOVA, Aziza SH.

    2001-01-01

    This paper deals with the derivation of common formulae for induced impurity photosensibility with an arbitrary set of energy levels in the semiconductor gap. We give the expression for the real recombinational situation with two types of impurity levels as well. The basic properties and certain common peculiarities concerning induced photoconductivity in semiconductors are under consideration.

  10. Steady-state organization of binary mixtures by active impurities

    DEFF Research Database (Denmark)

    Sabra, Mads Christian; Gilhøj, Henriette; Mouritsen, Ole G.

    1998-01-01

    The structural reorganization of a phase-separated binary mixture in the presence of an annealed dilution of active impurities is studied by computer-simulation techniques via a simple two-dimensional lattice-gas model. The impurities, each of which has two internal states with different affinity...

  11. Multiple magnetic impurities on surfaces: Scattering and quasiparticle interference

    NARCIS (Netherlands)

    Mitchell, A.

    2015-01-01

    We study systems of multiple interacting quantum impurities deposited on a metallic surface in a three-dimensional host. For the real-space two-impurity problem, using numerical renormalization group calculations, a rich range of behavior is shown to arise due to the interplay between Kondo physics

  12. Tight-Binding Description of Impurity States in Semiconductors

    Science.gov (United States)

    Dominguez-Adame, F.

    2012-01-01

    Introductory textbooks in solid state physics usually present the hydrogenic impurity model to calculate the energy of carriers bound to donors or acceptors in semiconductors. This model treats the pure semiconductor as a homogeneous medium and the impurity is represented as a fixed point charge. This approach is only valid for shallow impurities…

  13. Fluid and gyrokinetic simulations of impurity transport at JET

    DEFF Research Database (Denmark)

    Nordman, H; Skyman, A; Strand, P

    2011-01-01

    Impurity transport coefficients due to ion-temperature-gradient (ITG) mode and trapped-electron mode turbulence are calculated using profile data from dedicated impurity injection experiments at JET. Results obtained with a multi-fluid model are compared with quasi-linear and nonlinear gyrokineti...

  14. Effects of impurities on growth habit of KDP crystal

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The effects of metaphosphate, boric acid and quaternary ammonium cations with different concentration on the growth habit of KDP crystal are reported. The results are analyzed and discussed, which show that the effects of different impurities on the growth habit of KDP are not the same. It is due to the different adsorption mechanism of the impurities.

  15. The Mg impurity in nitride alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zvanut, M. E.; Willoughby, W. R.; Sunay, U. R. [Department of Physics, University of Alabama at Birmingham, Birmingham AL (United States); Koleske, D. D.; Allerman, A. A. [Sandia National Laboratory, Albuquerque NM (United States); Wang, Ke; Araki, Tsutomu [Department of Photonics, Ritsumeikan University, Kusatsu, Shiga (Japan); Nanishi, Yasushi [Department of Photonics, Ritsumeikan University, Kusatsu, Shiga, Japan and WCU Program, Department of Materials Science and Engineering, Seoul National University, Seoul (Korea, Republic of)

    2014-02-21

    Although several magnetic resonance studies address the Mg acceptor in GaN, there are few reports on Mg doping in the alloys, where hole production depends strongly on the Al or In content. Our electron paramagnetic resonance (EPR) measurements of the p-type alloys suggest that the Mg impurity retains the axial symmetry, characteristic of a p-type dopant in both alloys; however, In and Al produce additional, different characteristics of the acceptor. In InGaN, the behavior is consistent with a lowering of the acceptor level and increasing hole density as In concentration increases. For AlGaN, the amount of neutral Mg decreases with increasing Al content, which is attributed to different kinetics of hydrogen diffusion thought to occur in samples with higher Al mole fraction.

  16. Light-absorbing impurities in Arctic snow

    Directory of Open Access Journals (Sweden)

    S. J. Doherty

    2010-08-01

    Full Text Available Absorption of radiation by ice is extremely weak at visible and near-ultraviolet wavelengths, so small amounts of light-absorbing impurities in snow can dominate the absorption of solar radiation at these wavelengths, reducing the albedo relative to that of pure snow, contributing to the surface energy budget and leading to earlier snowmelt. In this study Arctic snow is surveyed for its content of light-absorbing impurities, expanding and updating the 1983–1984 survey of Clarke and Noone. Samples were collected in Alaska, Canada, Greenland, Svalbard, Norway, Russia, and the Arctic Ocean during 2005–2009, on tundra, glaciers, ice caps, sea ice, frozen lakes, and in boreal forests. Snow was collected mostly in spring, when the entire winter snowpack is accessible for sampling. Sampling was carried out in summer on the Greenland ice sheet and on the Arctic Ocean, of melting glacier snow and sea ice as well as cold snow. About 1200 snow samples have been analyzed for this study.

    The snow is melted and filtered; the filters are analyzed in a specially designed spectrophotometer system to infer the concentration of black carbon (BC, the fraction of absorption due to non-BC light-absorbing constituents and the absorption Ångstrom exponent of all particles. The reduction of snow albedo is primarily due to BC, but other impurities, principally brown (organic carbon, are typically responsible for ~40% of the visible and ultraviolet absorption. The meltwater from selected snow samples was saved for chemical analysis to identify sources of the impurities. Median BC amounts in surface snow are as follows (nanograms of carbon per gram of snow: Greenland 3, Arctic Ocean snow 7, melting sea ice 8, Arctic Canada 8, Subarctic Canada 14, Svalbard 13, Northern Norway 21, Western Arctic Russia 26, Northeastern Siberia 17. Concentrations are more variable in the European Arctic than in Arctic Canada or the Arctic Ocean, probably because of the proximity

  17. Gaussian impurity moving through a Bose-Einstein superfluid

    Science.gov (United States)

    Pinsker, Florian

    2017-09-01

    In this paper a finite Gaussian impurity moving through an equilibrium Bose-Einstein condensate at T = 0 is studied. The problem can be described by a Gross-Pitaevskii equation, which is solved perturbatively. The analysis is done for systems of 2 and 3 spatial dimensions. The Bogoliubov equation solutions for the condensate perturbed by a finite impurity are calculated in the co-moving frame. From these solutions the total energy of the perturbed system is determined as a function of the width and the amplitude of the moving Gaussian impurity and its velocity. In addition we derive the drag force the finite sized impurity approximately experiences as it moves through the superfluid, which proves the existence of a superfluid phase for finite extensions of the impurities below the speed of sound. Finally we find that the force increases with velocity until an inflection point from which it decreases again in 2 and 3d.

  18. Reduction of Oxygen Impurity in Multicrystalline Silicon Production

    Directory of Open Access Journals (Sweden)

    Bing Gao

    2013-01-01

    Full Text Available Effective control of oxygen impurity in multicrystalline silicon is required for the production of a high-quality crystal. The basic principle and some techniques for reducing oxygen impurity in multicrystalline silicon during the unidirectional solidification process are described in this paper. The oxygen impurity in multicrystalline silicon mainly originates from the silica crucible. To effectively reduce the oxygen impurity, it is essential to reduce the oxygen generation and enhance oxygen evaporation. For reduction of oxygen generation, it is necessary to prevent or weaken any chemical reaction with the crucible, and for the enhancement of oxygen evaporation, it is necessary to control convection direction of the melt and strengthen gas flow above the melt. Global numerical simulation, which includes heat transfer in global furnace, argon gas convection inside furnace, and impurity transport in both melt and gas regions, has been implemented to validate the above methods.

  19. Spectroscopic Analysis of Impurity Precipitates in CdS Films

    Energy Technology Data Exchange (ETDEWEB)

    Webb, J. D.; Keane, J.; Ribelin, R.; Gedvilas, L.; Swartzlander, A.; Ramanathan, K.; Albin, D. S.; Noufi, R.

    1999-10-31

    Impurities in cadmium sulfide (CdS) films are a concern in the fabrication of copper (indium, gallium) diselenide (CIGS) and cadmium telluride (CdTe) photovoltaic devices. Devices incorporating chemical-bath-deposited (CBD) CdS are comparable in quality to devices incorporating purer CdS films grown using vacuum deposition techniques, despite the higher impurity concentrations typically observed in the CBD CdS films. In this paper, we summarize and review the results of Fourier transform infrared (FTIR), Auger, electron microprobe, and X-ray photoelectron spectroscopic (XPS) analyses of the impurities in CBD CdS films. We show that these impurities differ as a function of substrate type and film deposition conditions. We also show that some of these impurities exist as 10{sup 2} micron-scale precipitates.

  20. [Impurity removal technology of Tongan injection in liquid preparation process].

    Science.gov (United States)

    Yang, Xu-fang; Wang, Xiu-hai; Bai, Wei-rong; Kang, Xiao-dong; Liu, Jun-chao; Wu, Yun; Xiao, Wei

    2015-08-01

    In order to effectively remove the invalid impurities in Tongan injection, optimize the optimal parameters of the impurity removal technology of liquid mixing process, in this paper, taking Tongan injection as the research object, with the contents of celandine alkali, and sinomenine, solids reduction efficiency, and related substances inspection as the evaluation indexes, the removal of impurities and related substances by the combined process of refrigeration, coction and activated carbon adsorption were investigated, the feasibility of the impurity removal method was definited and the process parameters were optimized. The optimized process parameters were as follows: refrigerated for 36 h, boiled for 15 min, activated carbon dosage of 0.3%, temperature 100 degrees C, adsorption time 10 min. It can effectively remove the tannin, and other impurities, thus ensure the quality and safety of products.

  1. Quantum dynamics of impurities coupled to a Fermi sea

    Science.gov (United States)

    Parish, Meera M.; Levinsen, Jesper

    2016-11-01

    We consider the dynamics of an impurity atom immersed in an ideal Fermi gas at zero temperature. We focus on the coherent quantum evolution of the impurity following a quench to strong impurity-fermion interactions, where the interactions are assumed to be short range like in cold-atom experiments. To approximately model the many-body time evolution, we use a truncated basis method, where at most two particle-hole excitations of the Fermi sea are included. When the system is initially noninteracting, we show that our method exactly captures the short-time dynamics following the quench, and we find that the overlap between initial and final states displays a universal nonanalytic dependence on time in this limit. We further demonstrate how our method can be used to compute the impurity spectral function, as well as describe many-body phenomena involving coupled impurity spin states, such as Rabi oscillations in a medium or highly engineered quantum quenches.

  2. Interplay of quantum impurities and topological surface modes

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Shi-Han; Deng, Ming-Xun; Qiu, Jian-Ming; Zhong, Qing-Hu; Yang, Mou; Wang, Rui-Qiang, E-mail: rqwanggzu@163.com

    2015-11-06

    The interplay of an Anderson quantum impurity with topological surface modes is studied. We find that the quantum impurity scattering can locally destroy the Dirac electron spectra by creating a significant resonance exactly at the Dirac point, in stark contrast to the case of classic impurities. When an external magnetic field is applied to the topological insulator (TI) surfaces, a bound state is found either at the gap edges or within the gap. We discuss the coexistence of the Kondo resonance and the bound state and their effect on TI local density of states. - Highlights: • A resonance at the Dirac point is found, differing from classic impurity theory. • A magnetic field-induced bound state is found within the energy gap. • Impurity Kondo resonance can cause corresponding signatures in the LDOS of TIs. • The results can be tuned by a gate voltage or a chemical potential.

  3. Micellar liquid chromatography of terephthalic acid impurities.

    Science.gov (United States)

    Richardson, Ashley E; McPherson, Shakeela D; Fasciano, Jennifer M; Pauls, Richard E; Danielson, Neil D

    2017-03-31

    The production of terephthalic acid (TPA) by oxidation of p-xylene is an important industrial process because high purity TPA is required for the synthesis of polyethylene terephthalate, the primary polymer used to make plastic beverage bottles. Few separation methods have been published that aim to separate TPA from eight major aromatic acid impurities. This work describes a "green" micellar liquid chromatography (MLC) method using a C18 column (100×2.1mm, 3.5μm), an acidic 1% sodium dodecyl sulfate (SDS) mobile phase, and a simple step flow rate gradient to separate TPA and eight impurities in less than 20min. The resulting chromatogram shows excellent peak shape and baseline resolution of all nine acids, in which there are two sets of isomers. Partition coefficients and equilibrium constants have been calculated for the two sets of isomers by plotting the reciprocal of the retention factor versus micelle concentration. Quantitation of the nine analytes in an actual industrial TPA sample is possible. Limits of detection for all nine acids range from 0.180 to 1.53ppm (2.16-19.3 pmoles) and limits of quantitation range from 0.549 to 3.45ppm (6.48-43.0 pmoles). In addition, the method was tested on two other reversed phase C18 columns of similar dimensions and particle diameter from different companies. Neither column showed quite the same peak resolution as the original column, however slight modifications to the mobile phase could improve the separation. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. The effect of carbon impurities on molybdenum surface morphology evolution under high-flux low-energy helium ion irradiation

    Science.gov (United States)

    Tripathi, J. K.; Novakowski, T. J.; Gonderman, S.; Bharadwaj, N.; Hassanein, A.

    2016-09-01

    We report on the role of carbon (C) impurities, in molybdenum (Mo) fuzz evolutions on Mo surface during 100 eV He+ ion irradiations. In this study we considered 0.01, 0.05, and 0.5% C+ ion impurities in He+ ion irradiations. For introducing such tiny C+ ion impurities, gas mixtures of He and CH4 have been chosen in following ratios; 99.95: 0.05, 99.75: 0.25, and 97.5: 2.5. Apart from these three cases, two additional cases, 100% He+ ion (for Mo fuzz growth due to only He+ ions) and 100% H+ ion (for confirming the significance of tiny 0.04-2.0% H+ ions in terms of Mo fuzz evolutions on Mo surface, if any), have also been considered. Ion energy (100 eV), ion fluence (2.6 × 1024 ions m-2), and target temperature (923 K) were kept constant for each experiment and their selections were based on our previous studies [1,2]. Our study shows homogeneously populated and highly dense Mo fuzz evolutions on entire Mo surface for 100% He+ ion irradiation case. Enhancement of C+ ion impurities in He+ ions causes a sequential reduction in Mo fuzz evolutions, leading to almost complete prevention of Mo fuzz evolutions for 0.5% C+ ion impurity concentrations. Additionally, no fuzz formation for 100% H+ ion irradiation at all, were seen (apart from some tiny nano-structuring, in very limited regions). This indicates that there is no significant role of H+ ions in Mo fuzz evolutions (at least for such tiny amount, 0.04-2.0% H+ ions). The study is significant to understand the behavior of potential high-Z plasma facing components (PFCs), in the, presence of tiny amount of C impurities, for nuclear fusion relevant applications.

  5. Extinguishing ELMs in detached radiative divertor plasmas

    Science.gov (United States)

    Pigarov, Alexander; Krasheninnikov, Sergei; Rognlien, Thomas

    2016-10-01

    In order to avoid deleterious effects of ELMs on PFCs in next-step fusion devices it has been suggested to operate with small-sized ELMs naturally extinguishing in the divertor. Our modeling effort is focusing at extinguishing type-I ELMs: conditions for expelled plasma dissipation; efficiency of ELM power handling by detached radiative divertors; and the ELM impact on detachment state. Here time-dependent modeling of a sequence of many ELMs was performed with 2-D edge plasma transport code UEDGE-MB-W which incorporates the Macro-Blob (MB) approach to simulate non-diffusive filamentary transport and various ``Wall'' (W) models for time-dependent hydrogen wall inventory and recycling. Three cases were modeled, in which extinguishing ELMs are achieved due to: (i) intrinsic impurities via graphite sputtering, (ii) extrinsic impurity gas puff (Ne), and (iii) =(i) +(ii). For each case, we performed a series of UEDGE-MB-W runs scanning the deuterium and impurity inventories, pedestal losses and ELM frequency. Temporal variations of the degree of detachment, ionization front shape, recombination sink strength, radiated fraction, peak power loads, OSP, impurity charge states, and in/out asymmetries were analyzed. We discuss the onset of extinguishing ELMs, conditions for not burning through and enhanced plasma recombination as functions of scanned parameters. Efficiencies of intrinsic and extrinsic impurities in ELM extinguishing are compared.

  6. Carbon transport and escape fraction in a high density plasma beam

    NARCIS (Netherlands)

    van Swaaij, G. A.; Bystrov, K.; Borodin, D.; Kirschner, A.; Zaharia, T.; van der Vegt, L. B.; De Temmerman, G.; W. J. Goedheer,

    2013-01-01

    Hydrocarbon injection experiments on molybdenum targets facing high-density plasmas in Pilot-PSI were simulated with the 3D Monte Carlo impurity transport and PSI code ERO. Impurity transport and calculation of redeposition profiles were decoupled by calculating carbon redistribution matrices with E

  7. A Study of the Flow Patterns of Expanding Impurity Aerosol Following a Disruption Event in a Fusion Reactor

    Science.gov (United States)

    Majumdar, Rudrodip

    The current study focuses on the adiabatic expansion of aerosol impurity in the post-disruption and thermal quench scenario inside the vacuum chamber of a fusion reactor. A pulsed electrothermal plasma (ET) capillary source has been used as a source term simulating the surface ablation of the divertor or other interior critical components of a tokamak fusion reactor under hard disruption-like conditions. The capillary source generates particulates from wall evaporation by depositing transient radiant high heat flux onto the inner liner of the capillary. The particulates form a plasma jet moving towards the capillary exit at high speed and high pressure. The first chapter discusses briefly the relevance of the study pertaining to the impurities in a fusion reactor based on the work available in the form of published literature. The second chapter discusses briefly the operating principle of a pulsed electrothermal plasma source (PEPS), the virtual integration of PEPS with 1-D electrothermal plasma flow solver ETFLOW and the use of capillary plasma sources in various industrial applications. The third chapter discusses about primitive computational work, backed by the data from actual electrothermal source experiments from the in-house facility "PIPE" (Plasma Interactions with Propellants Experiment), that shows the supersonic bulk flow patterns for the temperature, density, pressure, bulk velocity and the flow Mach number of the impurity particulates as they get ejected as a high-pressure, high-temperature and hyper-velocity jet from the simulated source term. It also shows the uniform steady-state subsonic expansion of bulk aerosol inside the expansion chamber. The fourth chapter discusses scaling laws in 1-D for the aforesaid bulk plasma parameters for ranges of axial length traversed by the flow, so that one can retrieve the flow parameters at some preferred locations. The fifth chapter discusses the effect of temperature and the non--linearity of the adiabatic

  8. Recent trends in the impurity profile of pharmaceuticals

    Directory of Open Access Journals (Sweden)

    Kavita Pilaniya

    2010-01-01

    Full Text Available Various regulatory authorities such as the International Conference on Harmonization (ICH, the United States Food and Drug administration (FDA, and the Canadian Drug and Health Agency (CDHA are emphasizing on the purity requirements and the identification of impurities in Active Pharmaceutical Ingredients (APIs. The various sources of impurity in pharmaceutical products are - reagents, heavy metals, ligands, catalysts, other materials like filter aids, charcoal, and the like, degraded end products obtained during \\ after manufacturing of bulk drugs from hydrolysis, photolytic cleavage, oxidative degradation, decarboxylation, enantiomeric impurity, and so on. The different pharmacopoeias such as the British Pharmacopoeia, United State Pharmacopoeia, and Indian Pharmacopoeia are slowly incorporating limits to allowable levels of impurities present in APIs or formulations. Various methods are used to isolate and characterize impurities in pharmaceuticals, such as, capillary electrophoresis, electron paramagnetic resonance, gas-liquid chromatography, gravimetric analysis, high performance liquid chromatography, solid-phase extraction methods, liquid-liquid extraction method, Ultraviolet Spectrometry, infrared spectroscopy, supercritical fluid extraction column chromatography, mass spectrometry, Nuclear magnetic resonance (NMR spectroscopy, and RAMAN spectroscopy. Among all hyphenated techniques, the most exploited techniques for impurity profiling of drugs are Liquid Chromatography (LC-Mass Spectroscopy (MS, LC-NMR, LC-NMR-MS, GC-MS, and LC-MS. This reveals the need and scope of impurity profiling of drugs in pharmaceutical research.

  9. Some aspects regarding impurities profile in fipronil-HPLC method

    Directory of Open Access Journals (Sweden)

    Ana Csuma,

    2011-12-01

    Full Text Available Using a substance as active pharmaceutical ingredient in veterinary drug formulation requires the characterization of this substance as content in active compound and so in terms of impurities possiblepresent in it, the latter being a mandatory requirement for a drug application. Fipronil is a synthetic product belonging to pesticide class used in veterinary practice to manufacture of some products against fleas, given spot–on or in form of spray, in cats and dogs. The main impurities in fipronil include process related impuritiesand degradation products as a result of exposure to environmental conditions: reduction, oxidation, photolysis and hydrolysis. A HPLC method suitable for analytical separation of fipronil from its impurities was established. Separation was achieved on a reversed phase column using a mixture of methanol, acetonitrile and water as mobile phase. In the chosen chromatographic conditions the resolution between fipronil and its sulphone (the main impurity was > 3 and the tailing factor (T < 2.0. Related impurities have absorbed in thesame band of UV wavelength as the main compound fipronil. Comparing the area of impurities obtained for sample solution with the area of the main peak in diluted standard solution allowed the detection of impurities at concentration < 0.1 %. Chromatographic separation on the same analytical column and detection at 280 nm was validated for assay of the content of active substance in fipronil used as ingredient in drug formulations.

  10. Impurity-limited resistance and phase interference of localized impurities under quasi-one dimensional nano-structures

    Energy Technology Data Exchange (ETDEWEB)

    Sano, Nobuyuki, E-mail: sano@esys.tsukuba.ac.jp [Institute of Applied Physics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8573 (Japan)

    2015-12-28

    The impurity-limited resistance and the effect of the phase interference among localized multiple impurities in the quasi-one dimensional (quasi-1D) nanowire structures are systematically investigated under the framework of the scattering theory. We derive theoretical expressions of the impurity-limited resistance in the nanowire under the linear response regime from the Landauer formula and from the Boltzmann transport equation (BTE) with the relaxation time approximation. We show that the formula from the BTE exactly coincides with that from the Landauer approach with the weak-scattering limit when the energy spectrum of the in-coming electrons from the reservoirs is narrow and, thus, point out a possibility that the distinction of the impurity-limited resistances derived from the Landauer formula and that of the BTE could be made clear. The derived formulas are applied to the quasi-1D nanowires doped with multiple localized impurities with short-range scattering potential and the validity of various approximations on the resistance are discussed. It is shown that impurity scattering becomes so strong under the nanowire structures that the weak-scattering limit breaks down in most cases. Thus, both phase interference and phase randomization simultaneously play a crucial role in determining the impurity-limited resistance even under the fully coherent framework. When the impurity separation along the wire axis direction is small, the constructive phase interference dominates and the resistance is much greater than the average resistance. As the separation becomes larger, however, it approaches the series resistance of the single-impurity resistance due to the phase randomization. Furthermore, under the uniform configuration of impurities, the space-average resistance of multiple impurities at room temperature is very close to the series resistance of the single-impurity resistance, and thus, each impurity could be regarded as an independent scattering center. The

  11. Impurities that cause difficulty in stripping actinides from commercial tetraalkylcarbamoylmethylphosphonates

    Energy Technology Data Exchange (ETDEWEB)

    Bahner, C. T.; Shoun, R. R.; McDowell, W. J.

    1977-09-01

    Dihexyl((diethylcarbamoyl)methyl)phosphonate (DHDECMP) in diethylbenzene extracts actinides well from 6 M nitric acid solution, but commercially available DHDECMP contains impurities which interfere with stripping the actinides from the organic extract. DHDECMP purified by molecular distillation does not contain these impurities, but the pot residue contains increased concentrations of them. Heating the purified DHDECMP causes the formation of products which interfere with stripping in the same way, suggesting that high temperatures employed in the manufacture of DHDECMP may produce the offending impurities. These impurities can be separated from the heat-decomposed material or the pot residues by dilution with a large volume of hexanes (causing part of the impurities to separate as a second liquid phase) followed by equilibration of the hexane solution with dilute alkali. After the treatment with hexane and dilute alkali, the DHDECMP is readily recovered and functions well in the actinide extraction process. Dibutyl((dibutylcarbamoyl)methyl)-phosphonate (DBDBCMP) and di(2-ethylhexyl)((diethylcarbamoyl)-methyl)phosphonate (DEHDECMP) are purified less effectively by these methods. Similar separation methods using diethylbenzene or CCl/sub 4/ as solvent do not remove impurities as completely as the hexane process. Impurities can also be removed from a benzene solution of the DHDECMP pot residue by passing it through a column packed with silica gel or diethylaminoethyl cellulose. These impurities have been separated into fractions for analytical examination by use of various solvents and by column chromatography. Hexyl hydrogen ((diethylcarbamoyl)methyl)-phosphonate has been identified tentatively as a principal objectionable impurity. Dihexyl phosphoric acid and possibly dihexylphosphonate have been identified in other fractions.

  12. Long-range exchange interaction between magnetic impurities in graphene

    Science.gov (United States)

    Agarwal, M.; Mishchenko, E. G.

    2017-02-01

    The effective spin exchange RKKY coupling between impurities (adatoms) on graphene mediated by conduction electrons is studied as a function of the strength of the potential part of the on-site energy U of the electron-adatom interaction. With increasing U , the exchange coupling becomes long range, determined largely by the impurity levels with energies close to the Dirac points. When adatoms reside on opposite sublattices, their exchange coupling, normally antiferromagnetic, becomes ferromagnetic and resonantly enhanced at a specific distance where an impurity level crosses the Dirac point.

  13. Negative compressibility observed in graphene containing resonant impurities

    Energy Technology Data Exchange (ETDEWEB)

    Chen, X. L.; Wang, L.; Li, W.; Wang, Y.; He, Y. H.; Wu, Z. F.; Han, Y.; Zhang, M. W.; Xiong, W.; Wang, N. [Department of Physics and The William Mong Institute of Nano Science and Technology, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)

    2013-05-20

    We observed negative compressibility in monolayer graphene containing resonant impurities under different magnetic fields. Hydrogenous impurities were introduced into graphene by electron beam (e-beam) irradiation. Resonant states located in the energy region of {+-}0.04 eV around the charge neutrality point were probed in e-beam-irradiated graphene capacitors. Theoretical results based on tight-binding and Lifshitz models agreed well with experimental observations of graphene containing a low concentration of resonant impurities. The interaction between resonant states and Landau levels was detected by varying the applied magnetic field. The interaction mechanisms and enhancement of the negative compressibility in disordered graphene are discussed.

  14. Generalized Wilson chain for solving multichannel quantum impurity problems

    Science.gov (United States)

    Mitchell, Andrew K.; Galpin, Martin R.; Wilson-Fletcher, Samuel; Logan, David E.; Bulla, Ralf

    2014-03-01

    The numerical renormalization group is used to solve quantum impurity problems, which describe magnetic impurities in metals, nanodevices, and correlated materials within dynamical mean field theory. Here we present a simple generalization of the Wilson chain, which improves the scaling of computational cost with the number of conduction bands, bringing more complex problems within reach. The method is applied to calculate the t matrix of the three-channel Kondo model at T =0, which shows universal crossovers near non-Fermi-liquid critical points. A nonintegrable three-impurity problem with three bands is also studied, revealing a rich phase diagram and novel screening and overscreening mechanisms.

  15. Thermal quantum discord in the Heisenberg chain with impurity

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Jia-Min, E-mail: jmgong@yeah.net; Hui, Zhan-Qiang

    2014-07-01

    We study thermal quantum discord (TQD) in the Heisenberg chain with spin site or magnetic impurity. The former one of which may induce inhomogeneous exchange interactions between the neighboring spins, while the latter one may model a spin chain with nonuniform magnetic field. In contrast to one's traditional understanding, we found that the spin impurity can be used to enhance the TQD greatly for all the bipartition schemes of the chain, while the magnetic impurity located on one spin can make the TQD between the other two spins approaching its maximum 1 for the antiferromagnetic chain.

  16. Exact Solution for Perk-Schultz Model with Boundary Impurities *

    Institute of Scientific and Technical Information of China (English)

    LI Guang-Liang; YUE Rui-Hong; SHI Kang-Jie; HOU Bo-Yu

    2001-01-01

    The Perk-Schultz model with SUq(m|n) spin boundary impurities is constructed by dressing the c-number reflecting K-matrix with the local L-matrix which acts non-trivially on an impurity Hilbert space. The eigenvalue of the transfer matrix and the corresponding Bethe ansatz equations with different c-number reflecting K-matrices are obtained by using the nested Bethe ansatz method (m ≠ n). When m = 1,n = 2, our results come back to that of supersymmetric t - J model with SUq(1|2) spin boundary impurities.

  17. Effect of oxygen impurities on atmospheric-pressure surface streamer discharge in argon for large gap arc breakdown

    Science.gov (United States)

    Sharma, Ashish; Levko, Dmitry; Raja, Laxminarayan L.

    2016-10-01

    We report the results of a computational study that investigates the effect of impurities (molecular oxygen) on the development of argon surface streamers at atmospheric-pressure conditions. A continuous surface streamer has been proposed as a low-voltage mechanism to generate a conductive bridge for arc breakdown of a large interelectrode gap at high pressures. The streamer discharge model is based on the self-consistent, multispecies, continuum description of the plasma. Below a threshold voltage, no streamer discharge is observed and charge is localized only in the vicinity of the anode in the form of a localized corona. Above this voltage threshold in pure argon, a continuous conductive streamer successfully bridges the gap between two electrodes indicating high probability of transition to the arc. For small oxygen impurities (less than 5%), the threshold voltage is found to decrease by a few hundred volts compared to the threshold voltage in pure argon while the streamer induction time increases. No noticeable changes in the streamer conductivity is obtained for low impurities of oxygen in the above range. An increase of the oxygen density above the 5% impurity level causes a significant decrease in the continuous streamer conductivity and leads to a decrease in the probability of transition to arc.

  18. Clean Chemistry for Elemental Impurities Analysis of Pharmaceuticals in Compliance with USP 232.

    Science.gov (United States)

    Jin, Chunguang

    2016-10-01

    United States Pharmacopeia updated its 100 years old metal analysis method with inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES). These sensitive instruments require that sample preparation be at least as sophisticated as the instrumentation used in the analysis. Sample contamination during sample preparation has to be controlled to an acceptable level given the low detection limit of these instruments and the ubiquitous presence of elements. This article focused on sample contamination during sample preparation. Contaminations from environment, reagents, and lab apparatus were investigated for their impact on trace element analysis. Advice on clean lab practice was offered to the pharmaceutical industry in regard to contamination control in elemental analysis labs at a time when the industry is preparing for compliance with elemental impurities in drug products.

  19. Transient snakes in an ohmic plasma associated with a minor disruption in the HT-7 Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Songtao; Xu, Liqing; Hu, Liqun; Chen, Kaiyun [Chinese Academy of Sciences, Hefei (China)

    2014-05-15

    A transient burst (∼2 ms, an order of the fast-particle slowdown timescale) of a spontaneous snake is observed for the first time in a HT-7 heavy impurity ohmic plasma. The features of the low-Z impurity snake are presented. The flatten electron profile due to the heavy impurity reveals the formation of a large magnetic island. The foot of the impurity accumulation is consistent with the location of the transient snake. The strong frequency-chirping behaviors and the spatial structures of the snake are also presented.

  20. On Clustering Impurities by Liquid Density Fluctuations

    Directory of Open Access Journals (Sweden)

    Alexander L. Shimkevich

    2010-01-01

    Full Text Available Recent developments in liquid technology have created a new class of fluids called “nanofluids” which are two-phase mixtures of a non-metal-liquid matrix and addon particles usually less than 100 nm in size. It is reputed that such liquids have a great potential for application. Indeed, many tests have shown that their thermal conductivity can be increased by almost 20% compared to that of the base fluids for a relatively low particle loading (of 1 up to 5% in volume. It is confirmed by experimental data and simulation results. In this study, the author considers an effect of impurity clustering by liquid density fluctuations as a natural mechanism for stabilizing microstructure of the colloidal solution and estimates the effect of fractal structure of colloidal particles on thermal conductivity of water. The results of this study may be useful for motivating choosing the composition of heat-transfer suspension and developing technology for making the appropriate nanofluid.

  1. Impurity trapped excitons under high hydrostatic pressure

    Science.gov (United States)

    Grinberg, Marek

    2013-09-01

    Paper summarizes the results on pressure effect on energies of the 4fn → 4fn and 4fn-15d1 → 4fn transitions as well as influence of pressure on anomalous luminescence in Lnα+ doped oxides and fluorides. A model of impurity trapped exciton (ITE) was developed. Two types of ITE were considered. The first where a hole is localized at the Lnα+ ion (creation of Ln(α+1)+) and an electron is attracted by Coulomb potential at Rydberg-like states and the second where an electron captured at the Lnα+ ion (creation of Ln(α-1)+) and a hole is attracted by Coulomb potential at Rydberg-like states. Paper presents detailed analysis of nonlinear changes of energy of anomalous luminescence of BaxSr1-xF2:Eu2+ (x > 0.3) and LiBaF3:Eu2+, and relate them to ITE-4f65d1 states mixing.

  2. Impurity Trapping of Positive Muons in Metals

    CERN Multimedia

    2002-01-01

    Polarized positive muons are implanted into metal samples. In an applied magnetic field the muon spin precession is studied. The line width in the precession frequency spectrum gives information about the static and dynamic properties of muons in a metal lattice. At temperatures where the muon is immobile within its lifetime the line width gives information about the site of location. At temperatures where the muon is mobile, the line width gives information on the diffusion process. It is known from experiments on quasi-elastic neutron scattering on hydrogen in niobium that interstitial impurities like nitrogen tend to act as traps for hydrogen. These trapping effects have now been studied systematically for muons in both f.c.c. metals (aluminium and copper) and b.c.c. metals (mainly niobium). Direct information on the trapping rates and the nature of the diffusion processes can be obtained since the muonic lifetime covers a time range where many of these processes occur.\\\\ \\\\ Mathematical models are set up ...

  3. A bijection theorem for domino tiling with diagonal impurities

    CERN Document Server

    Nakano, Fumihiko

    2009-01-01

    We consider the dimer problem on a non-bipartite graph $G$, where there are two types of dimers one of which we regard impurities. Results of simulations using Markov chain seem to indicate that impurities are tend to distribute on the boundary, which we set as a conjecture. We first show that there is a bijection between the set of dimer coverings on $G$ and the set of spanning forests on two graphs which are made from $G$, with configuration of impurities satisfying a pairing condition. This bijection can be regarded as a extension of the Temperley bijection. We consider local move consisting of two operations, and by using the bijection mentioned above, we prove local move connectedness. We further obtained some bound of the number of dimer coverings and the probability finding an impurity at given edge, by extending the argument in our previous result.

  4. Effect of impurities in industrial salts on aluminum scrap melting

    Energy Technology Data Exchange (ETDEWEB)

    Ye, J.; Sahai, Y. [Ohio State Univ., Columbus, OH (United States). Dept. of Materials Science and Engineering; Revet, A. [Kalium Canada, ltd., Regina, Saskatchewan (Canada)

    1996-10-01

    Aluminum scrap such as Used Beverage Containers (UBC) is melted under a protective molten salt cover. An appropriate salt protects metal from oxidation, promotes coalescence of molten droplets, and separates clean metal from the oxide contamination. Generally, the salt compositions for aluminum scrap recycling are based on equimolar mixtures of NaCl and KCl. A small amount of fluoride is also added in the salt. In the past, laboratory research at universities and industrial laboratories have been limited to pure salts. However, the industrial salts have impurities such as sulfates and other insoluble materials. These impurities have a pronounced effect on the efficiency of the scrap remelting process. In this paper, the role of impurities in industrial salts in terms of their chemical interactions with the metal are summarized. The efficiency of different industrial grade salts containing varying amounts of sulfates and other insoluble impurities for scrap recycling is compared.

  5. Simulating the symmetron: domain walls and symmetry-restoring impurities

    CERN Document Server

    Pearson, Jonathan A

    2014-01-01

    In this paper we study the dynamics of relativistic domain walls in the presence of static symmetry-restoring impurities. The field theory is precisely the same as what is known to cosmologists as the "symmetron model", whereby the usual $\\mathbb{Z}_2$ symmetry breaking potential is appended with a space-varying mass-term (the space-variation is set by the profile of the impurity, which we take to be a "tanh"-function). After presenting the outcomes of a suite of different numerical experiments we have three main results: (1) domain walls pin to impurities, (2) domain wall necklaces can be energetically preferred configurations, and (3) impurities significantly modifies the usual ${N}_{\\rm dw}\\propto t^{-1}$ scaling law for random networks of domain walls.

  6. Magnetic impurity transition in a (d + s)-wave superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Borkowski, L.S. [Quantum Physics Division, Faculty of Physics, A. Mickiewicz University, Umultowska 85, 61-614 Poznan (Poland)

    2010-03-15

    We consider the superconducting state of d + s symmetry with finite concentration of Anderson impurities in the limit {delta}{sub s} /{delta}{sub d} << 1. The model consists of a BCS-like term in the Hamiltonian and the Anderson impurity treated in the self-consistent large-N mean field approximation. Increasing impurity concentration or lowering the ratio {delta}{sub s} /{delta}{sub d} drives the system through a transition from a state with two sharp peaks at low energies and exponentially small density of states at the Fermi level to one with N(0) {approx_equal}({delta}{sub s} /{delta}{sub d}){sup 2}. This transition is discontinuous if the energy of the impurity resonance is the smallest energy scale in the problem. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  7. Effects of the equilibrium model on impurity transport in tokamaks

    CERN Document Server

    Skyman, Andreas; Tegnered, Daniel; Nordman, Hans; Anderson, Johan; Strand, Pär

    2014-01-01

    Gyrokinetic simulations of ion temperature gradient mode and trapped electron mode driven impurity transport in a realistic tokamak geometry are presented and compared with results using simplified geometries. The gyrokinetic results, obtained with the GENE code in both linear and non-linear modes are compared with data and analysis for a dedicated impurity injection discharge at JET. The impact of several factors on heat and particle transport is discussed, lending special focus to tokamak geometry and rotational shear. To this end, results using s-alpha and concentric circular equilibria are compared with results with magnetic geometry from a JET experiment. To further approach experimental conditions, non-linear gyrokinetic simulations are performed with collisions and a carbon background included. The impurity peaking factors, computed by finding local density gradients corresponding to zero particle flux, are discussed. The impurity peaking factors are seen to be reduced by a factor of ~2 in realistic ge...

  8. Mechanisms, kinetics, impurities and defects: consequences in macromolecular crystallization

    OpenAIRE

    McPherson, Alexander; Kuznetsov, Yurii G

    2014-01-01

    New imaging techniques, particularly AFM, permitted the elucidation of the mechanisms for protein and virus crystal growth. They have also allowed direct visualization of crystal defect structure and the consequences of impurity incorporation.

  9. Surface Kondo Impurities in the Slave-Boson Approach

    Science.gov (United States)

    Anda, Enrique; Vernek, Edson

    2005-03-01

    Transport properties of magnetic impurities on surfaces have captured a great deal of attention lately. Atom manipulation and topographic imaging techniques using scanning tunneling microscope have confirmed some theoretical predictions on Kondo physics and at the same time revealed other interesting behavior in these systems. For example, experiments have reported unexpectedly high Kondo temperatures for multi-impurity and molecular structures on metallic surfaces. Motivated by these experimental results we apply slave boson techniques for finite Coulomb interaction (finite U) to study the transport properties of magnetic impurities on a metallic surface in the Kondo regime. We report here on our studies of the role of fluctuations on the slave boson number for the case of one impurity on metallic surfaces. We compare our results to other theoretical approaches and to experimental results. Supported by CAPES-Brazil and NSF-IMC and NSF-NIRT.

  10. Energy levels of isoelectronic impurities by large scale LDA calculations

    CERN Document Server

    Li, J

    2002-01-01

    Isoelectronic impurity states are localized states induced by stoichiometric single atom substitution in bulk semiconductor. Photoluminescence spectra indicate deep impurity levels of 0.5 to 0.9eV above the top of valence band for systems like: GaN:As, GaN:P, CdS:Te, ZnS:Te. Previous calculations based on small supercells seemingly confirmed these experimental results. However, the current ab initio calculations based on thousand atom supercells indicate that the impurity levels of the above systems are actually much shallower(0.04 to 0.23 eV), and these impurity levels should be compared with photoluminescence excitation spectra, not photoluminescence spectra.

  11. Energy levels of isoelectronic impurities by large scale LDA calculations

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jingbo; Wang, Lin-Wang

    2002-11-22

    Isoelectronic impurity states are localized states induced by stoichiometric single atom substitution in bulk semiconductor. Photoluminescence spectra indicate deep impurity levels of 0.5 to 0.9eV above the top of valence band for systems like: GaN:As, GaN:P, CdS:Te, ZnS:Te. Previous calculations based on small supercells seemingly confirmed these experimental results. However, the current ab initio calculations based on thousand atom supercells indicate that the impurity levels of the above systems are actually much shallower(0.04 to 0.23 eV), and these impurity levels should be compared with photoluminescence excitation spectra, not photoluminescence spectra.

  12. Fermionic impurities in Chern-Simons-matter theories

    Science.gov (United States)

    Benincasa, Paolo; Ramallo, Alfonso V.

    2012-02-01

    We study the addition of quantum fermionic impurities to the mathcal{N} = 6 super-symmetric Chern-Simons-matter theories in 2 + 1 spacetime dimensions. The impurities are introduced by means of Wilson loops in the antisymmetric representation of the gauge group. In a holographic setup, the system is represented by considering D6-branes probing the AdS 4 × mathbb{C}mathbb{P} 3 background of type IIA supergravity. We study the thermodynamic properties of the system and show how a Kondo lattice model with holographic dimers can be constructed. By computing the Kaluza-Klein fluctuation modes of the probe brane we determine the complete spectrum of dimensions of the impurity operators. A very rich structure is found, depending both on the Kaluza-Klein quantum numbers and on the filling fraction of the impurities.

  13. Fermionic impurities in Chern-Simons-matter theories

    CERN Document Server

    Benincasa, Paolo

    2011-01-01

    We study the addition of quantum fermionic impurities to the N=6 supersymmetric Chern-Simons-matter theories in 2+1 spacetime dimensions. The impurities are introduced by means of Wilson loops in the antisymmetric representation of the gauge group. In a holographic setup, the system is represented by considering D6-branes probing the AdS_4 x CP^3 background of type IIA supergravity. We study the thermodynamic properties of the system and show how a Kondo lattice model with holographic dimers can be constructed. By computing the Kaluza-Klein fluctuation modes of the probe brane we determine the complete spectrum of dimensions of the impurity operators. A very rich structure is found, depending both on the Kaluza-Klein quantum numbers and on the filling fraction of the impurities.

  14. A LIBS method for simultaneous monitoring of the impurities and the hydrogenic composition present in the wall of the TJ-II stellarator

    Science.gov (United States)

    López-Miranda, B.; Zurro, B.; Baciero, A.; Martínez, M.

    2016-11-01

    The study of plasma-wall interactions and impurity transport in the plasma fusion devices is critical for the development of future fusion reactors. An experiment to perform laser induced breakdown spectroscopy, using minor modifications of our existing laser blow-off impurity injection system, has been set up thus making both experiments compatible. The radiation produced by the laser pulse focused at the TJ-II wall evaporates a surface layer of deposited impurities and the subsequent radiation produced by the laser-produced plasma is collected by two separate lens and fiber combinations into two spectrometers. The first spectrometer, with low spectral resolution, records a spectrum from 200 to 900 nm to give a survey of impurities present in the wall. The second one, with high resolution, is tuned to the wavelengths of the Hα and Dα lines in order to resolve them and quantify the hydrogen isotopic ratio present on the surface of the wall. The alignment, calibration, and spectral analysis method will be described in detail. First experimental results obtained with this setup will be shown and its relevance for the TJ-II experimental program discussed.

  15. A LIBS method for simultaneous monitoring of the impurities and the hydrogenic composition present in the wall of the TJ-II stellarator

    Energy Technology Data Exchange (ETDEWEB)

    López-Miranda, B., E-mail: belen.lopez@ciemat.es; Zurro, B.; Baciero, A. [Laboratorio Nacional de Fusión, CIEMAT, Av. Complutense, 40, 28040 Madrid (Spain); Martínez, M. [Universidad Carlos III de Madrid, Av de la Universidad, 30, 28911 Leganés, Madrid (Spain)

    2016-11-15

    The study of plasma-wall interactions and impurity transport in the plasma fusion devices is critical for the development of future fusion reactors. An experiment to perform laser induced breakdown spectroscopy, using minor modifications of our existing laser blow-off impurity injection system, has been set up thus making both experiments compatible. The radiation produced by the laser pulse focused at the TJ-II wall evaporates a surface layer of deposited impurities and the subsequent radiation produced by the laser-produced plasma is collected by two separate lens and fiber combinations into two spectrometers. The first spectrometer, with low spectral resolution, records a spectrum from 200 to 900 nm to give a survey of impurities present in the wall. The second one, with high resolution, is tuned to the wavelengths of the Hα and Dα lines in order to resolve them and quantify the hydrogen isotopic ratio present on the surface of the wall. The alignment, calibration, and spectral analysis method will be described in detail. First experimental results obtained with this setup will be shown and its relevance for the TJ-II experimental program discussed.

  16. Passive Spectroscopic Diagnostics for Magnetically-confined Fusion Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Stratton, B. C.; Biter, M.; Hill, K. W.; Hillis, D. L.; Hogan, J. T.

    2007-07-18

    Spectroscopy of radiation emitted by impurities and hydrogen isotopes plays an important role in the study of magnetically-confined fusion plasmas, both in determining the effects of impurities on plasma behavior and in measurements of plasma parameters such as electron and ion temperatures and densities, particle transport, and particle influx rates. This paper reviews spectroscopic diagnostics of plasma radiation that are excited by collisional processes in the plasma, which are termed 'passive' spectroscopic diagnostics to distinguish them from 'active' spectroscopic diagnostics involving injected particle and laser beams. A brief overview of the ionization balance in hot plasmas and the relevant line and continuum radiation excitation mechanisms is given. Instrumentation in the soft X-ray, vacuum ultraviolet, ultraviolet, visible, and near-infrared regions of the spectrum is described and examples of measurements are given. Paths for further development of these measurements and issues for their implementation in a burning plasma environment are discussed.

  17. On the state of Mn impurity implanted in Si

    Energy Technology Data Exchange (ETDEWEB)

    Orlov, A. F., E-mail: rmdp@girmet.ru [State Institute for Rare Metals (Russian Federation); Bublik, V. T. [Moscow State Institute of Steel and Alloys (Russian Federation); Vdovin, V. I. [Institute for Chemical Problems of Microelectronics (Russian Federation); Agafonov, Yu. A. [Russian Academy of Sciences, Institute of Microelectronics, Technology, and High Purity Materials (Russian Federation); Balagurov, L. A. [State Institute for Rare Metals (Russian Federation); Zinenko, V. I. [Russian Academy of Sciences, Institute of Microelectronics, Technology, and High Purity Materials (Russian Federation); Kulemanov, I. V. [State Institute for Rare Metals (Russian Federation); Shcherbachev, K. D. [Moscow State Institute of Steel and Alloys (Russian Federation)

    2009-07-15

    The state of manganese impurity in implanted silicon at implantation doses of up to 5 x 10{sup 16} cm{sup -2} has been investigated by X-ray diffraction and transmission electron microscopy. It is established that, after short-term vacuum annealing at 850{sup o}C, most of the implanted manganese impurities are in microinclusions up to 20 nm in size formed by a tetragonal silicide phase of the Mn{sub 15}Si{sub 26} type.

  18. Thermal Conductivity of Nanotubes: Effects of Chirality and Isotope Impurity

    OpenAIRE

    Gang, Zhang; Li, Baowen

    2005-01-01

    We study the dependence of thermal conductivity of single walled nanotubes (SWNT) on chirality and isotope impurity by nonequilibrium molecular dynamics method with accurate potentials. It is found that, contrary to electronic conductivity, the thermal conductivity is insensitive to the chirality. The isotope impurity, however, can reduce the thermal conductivity up to 60% and change the temperature dependence behavior. We also study the dependence of thermal conductivity on tube length for t...

  19. Acetylated Lysozyme as Impurity in Lysozyme Crystals: Constant Distribution Coefficient

    Science.gov (United States)

    Thomas, B. R.; Chernov, A. A.

    2000-01-01

    Hen egg white lysozyme (HEWL) was acetylated to modify molecular charge keeping the molecular size and weight nearly constant. Two derivatives, A and B, more and less acetylated, respectively, were obtained, separated, purified and added to the solution from which crystals of tetragonal HEWL crystals were grown. Amounts of the A or B impurities added were 0.76, 0.38 and 0.1 milligram per millimeter while HEWL concentration were 20, 30 and 40 milligram per milliliter. The crystals grown in 18 experiments for each impurity were dissolved and quantities of A or B additives in these crystals were analyzed by cation exchange high performance liquid chromatography. All the data for each set of 18 samples with the different impurity and regular HEWL concentrations is well described by one distribution coefficient K = 2.15 plus or minus 0.13 for A and K = 3.42 plus or minus 0.25 for B. The observed independence of the distribution coefficient on both the impurity concentration and supersaturation is explained by the dilution model described in this paper. It shows that impurity adsorption and incorporation rate is proportional to the impurity concentration and that the growth rate is proportional to the crystallizing protein in solution. With the kinetic coefficient for crystallization, beta = 5.10(exp -7) centimeters per second, the frequency at which an impurity molecule near the growing interface irreversibly joins a molecular site on the crystal was found to be 3 1 per second, much higher than the average frequency for crystal molecules. For best quality protein crystals it is better to have low microheterogeneous protein impurity concentration and high supers aturation.

  20. Phase Transition of Spin-Peierls Systems with Impurities

    Institute of Scientific and Technical Information of China (English)

    XU Bo-Wei; DING Guo-Hui; YE Fei

    2000-01-01

    The quasi-one-dimensional spin-Peierls(SP) systems with impurities are studied in their bosonized form. The spins of the dimerized state are bounded into singlets with an SP gap, while the impurities of doped systems will induce fluctuations of the coupling strength between the spins at different sites and break some pairs of spin singlets. The doping suppresses the dimerized SP state and induces a Kosterlitz-Thouless phase transition from the dimerized state into the undimerized one.

  1. Impurity modes in the one-dimensional XXZ Heisenberg model

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, J.M. [Departamento de Física, Universidade Federal do Piauí, Campus Ministro Petrônio Portella, 57072-970 Teresina, Piauí (Brazil); Leite, R.V. [Centro de Ciências Exatas e Tecnologia, Curso de Física, Universidade Estadual Vale do Acaraú, Av. Dr. Guarany 317, Campus Cidao, 62040-730 Sobral, Ceará (Brazil); Landim, R.R. [Departamento de Física, Universidade Federal do Ceará, Caixa Postal 6030, Campus do Pici, 60455-760 Fortaleza, Ceará (Brazil); Costa Filho, R.N., E-mail: rai@fisica.ufc.br [Departamento de Física, Universidade Federal do Ceará, Caixa Postal 6030, Campus do Pici, 60455-760 Fortaleza, Ceará (Brazil)

    2014-04-01

    A Green's function formalism is used to calculate the energy of impurity modes associated with one and/or two magnetic impurities in the one-dimensional Heisenberg XXZ magnetic chain. The system can be tuned from the Heisenberg to the Ising model varying a parameter λ. A numerical study is performed showing two types of localized modes (s and p). The modes depend on λ and the degeneracy of the acoustic modes is broken.

  2. The effect of magnetic impurity scattering in Au films

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The magnetic impurity scattering plays an important role in the phase coherence behavior of thin films.By using the thickness and disorder dependences of the low temperature logarithmic anomaly in resistivity we are able to determine the concentration of magnetic impurities in Au films and demonstrate that the low temperature saturation or plateau in phase decoherence time is closely related with the Kondo effect.

  3. The effects of naturally occurring impurities in rock salt

    Indian Academy of Sciences (India)

    Alina-Mihaela Badescu; Alexandra Saftoiu

    2014-09-01

    In this paper we investigate the effect that naturally occurring impurities in salt mines have both on effective permittivity of the medium and on radio wave propagation at ∼200 MHz. The effective permittivity is determined based on the dielectric properties of salt and the characteristics of the main impurities. We conclude that at such frequencies the scattering is negligible compared to absorptions. The effect of trapped water in different forms is also evaluated.

  4. Sensitivity of graphene flakes and nanorings to impurities

    Energy Technology Data Exchange (ETDEWEB)

    Konobeeva, N.N., E-mail: yana_nn@volsu.ru [Volgograd State University, University Avenue 100, Volgograd 400062 (Russian Federation); Belonenko, M.B. [Volgograd State University, University Avenue 100, Volgograd 400062 (Russian Federation); Volgograd Institute of Business, Uzhno-Ukrainskaya Str., Volgograd 400048 (Russian Federation)

    2017-06-01

    In this paper, we consider the influence of impurity on the graphene flakes and nanorings conductance. Based on the jumping Hamiltonian for graphene electrons with its direct diagonalization, we obtain the density of states. Further, the tunneling current is calculated for the following contacts: graphene flake-metal, graphene flake-quantum dots, graphene nanoring-quantum dots. We analyze the effect of the flake dimensions and the positions of the adsorbed molecule of impurity on the characteristic properties of the tunneling current.

  5. Classical impurities and boundary Majorana zero modes in quantum chains

    Science.gov (United States)

    Müller, Markus; Nersesyan, Alexander A.

    2016-09-01

    We study the response of classical impurities in quantum Ising chains. The Z2 degeneracy they entail renders the existence of two decoupled Majorana modes at zero energy, an exact property of a finite system at arbitrary values of its bulk parameters. We trace the evolution of these modes across the transition from the disordered phase to the ordered one and analyze the concomitant qualitative changes of local magnetic properties of an isolated impurity. In the disordered phase, the two ground states differ only close to the impurity, and they are related by the action of an explicitly constructed quasi-local operator. In this phase the local transverse spin susceptibility follows a Curie law. The critical response of a boundary impurity is logarithmically divergent and maps to the two-channel Kondo problem, while it saturates for critical bulk impurities, as well as in the ordered phase. The results for the Ising chain translate to the related problem of a resonant level coupled to a 1d p-wave superconductor or a Peierls chain, whereby the magnetic order is mapped to topological order. We find that the topological phase always exhibits a continuous impurity response to local fields as a result of the level repulsion of local levels from the boundary Majorana zero mode. In contrast, the disordered phase generically features a discontinuous magnetization or charging response. This difference constitutes a general thermodynamic fingerprint of topological order in phases with a bulk gap.

  6. Synthesis, Isolation and Characterization of Process-Related Impurities in Oseltamivir Phosphate

    Directory of Open Access Journals (Sweden)

    Yogesh Kumar Sharma

    2012-01-01

    Full Text Available Three known impurities in oseltamivir phosphate bulk drug at level 0.1% (ranging from 0.05-0.1% were detected by gradient reverse phase high performance liquid chromatography. These impurities were preliminarily identified by the mass number of the impurities. Different experiments were conducted and finally the known impurities were synthesized and characterized.

  7. Impurities removal by laser blow-off from in-vacuum optical surfaces on RFX-mod experiment.

    Science.gov (United States)

    Alfier, A; Barison, S; Fassina, A; Fiameni, S; Giudicotti, L; Pasqualotto, R; Cervaro, V; Lotto, L

    2010-12-01

    An in situ window cleaning system by laser blow-off through optical fiber has been developed on the basis of a feasibility study previously presented. The beam generated by a Q-switched Nd:YAG laser is launched in a vacuum box into a high damage threshold optical fiber through a lens. The fiber output is focused on the impurities-coated surface of a vacuum window exposed to the plasma of the RFX-mod experiment, and it is remotely controlled with an xy motion system to scan the entire surface. We first investigate the energy density threshold necessary to ablate the deposited impurity substrate on removed dirty windows: above threshold, a single laser pulse recovers ∼95% of the window transmission before its exposure to the plasma, while below it the efficiency of the cleaning process is too poor. The system so conceived was then used to clean the three collection windows of the Main Thomson scattering diagnostic on RFX-mod. We also present results obtained applying the same technique to the SiO-protected Al mirror used for the Z(eff) diagnostic: an energy threshold for efficient impurity removal without mirror damage is first identified, then ablation tests are executed and analyzed in terms of recovered reflectivity. The SIMS technique is used both with windows and mirror to study the composition of surfaces before and after the ablation.

  8. Effect of neutral hydrogen on edge impurity behavior in stochastic magnetic field layer of Large Helical Device

    Energy Technology Data Exchange (ETDEWEB)

    Morita, S., E-mail: morita@nifs.ac.jp [National Institute for Fusion Science, Toki 509-5292, Gifu (Japan); Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Gifu (Japan); Kobayashi, M.; Oishi, T. [National Institute for Fusion Science, Toki 509-5292, Gifu (Japan); Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Gifu (Japan); Zhang, H.M. [Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Gifu (Japan); Goto, M. [National Institute for Fusion Science, Toki 509-5292, Gifu (Japan); Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Gifu (Japan); Cui, Z.Y.; Dong, C.F. [Southwestern Institute of Physics, P.O. Box 432, Chengdu 610041, Sichuan (China); Hu, L.Q. [Institute of Plasma Physics, P.O.Box 1126, Hefei 230031, Anhui (China); Huang, X.L. [Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Gifu (Japan); Kawamura, G.; Masuzaki, S. [National Institute for Fusion Science, Toki 509-5292, Gifu (Japan); Murakami, I. [National Institute for Fusion Science, Toki 509-5292, Gifu (Japan); Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292, Gifu (Japan); Wang, E.H. [Institute of Plasma Physics, P.O.Box 1126, Hefei 230031, Anhui (China)

    2015-08-15

    Two-dimensional (2-D) distribution of impurity line emissions has been measured with 2-D extreme ultraviolet (EUV) spectroscopy in Large Helical Device (LHD) for studying the edge impurity transport in stochastic magnetic field layer with three-dimensional (3-D) structure. The impurity behavior in the vicinity of two X-points at inboard and outboard sides of the toroidal plasma can be separately examined with the 2-D measurement. As a result, it is found that the carbon location changes from inboard to outboard X-points when the plasma axis is shifted from R{sub ax} = 3.6 m to 3.75 m. A 3-D simulation with EMC3-EIRENE code agrees with the result at R{sub ax} = 3.75 m but disagreed with the result at R{sub ax} = 3.60 m. The discrepancy between the measurement and simulation at R{sub ax} = 3.60 m is considerably reduced when an effect of neutral hydrogen localized in the inboard side is taken into account, which can modify the density gradient and friction force along the magnetic field.

  9. Dressed topological insulators. Rashba impurity, Kondo effect, magnetic impurities, proximity-induced superconductivity, hybrid systems

    Energy Technology Data Exchange (ETDEWEB)

    Posske, Thore Hagen

    2016-02-26

    Topological insulators are electronic phases that insulate in the bulk and accommodate a peculiar, metallic edge liquid with a spin-dependent dispersion. They are regarded to be of considerable future use in spintronics and for quantum computation. Besides determining the intrinsic properties of this rather novel electronic phase, considering its combination with well-known physical systems can generate genuinely new physics. In this thesis, we report on such combinations including topological insulators. Specifically, we analyze an attached Rashba impurity, a Kondo dot in the two channel setup, magnetic impurities on the surface of a strong three-dimensional topological insulator, the proximity coupling of the latter system to a superconductor, and hybrid systems consisting of a topological insulator and a semimetal. Let us summarize our primary results. Firstly, we determine an analytical formula for the Kondo cloud and describe its possible detection in current correlations far away from the Kondo region. We thereby rely on and extend the method of refermionizable points. Furthermore, we find a class of gapless topological superconductors and semimetals, which accommodate edge states that behave similarly to the ones of globally gapped topological phases. Unexpectedly, we also find edge states that change their chirality when affected by sufficiently strong disorder. We regard the presented research helpful in future classifications and applications of systems containing topological insulators, of which we propose some examples.

  10. Zeroth Order Phase Transition in a Holographic Superconductor with Single Impurity

    CERN Document Server

    Zeng, Hua Bi

    2014-01-01

    We studied the single normal impurity effect in superconductor by using the holographic method. When the size of impurity is much smaller compared to the host superconductor, we reproduced the Anderson theorem, which states that a conventional s-wave superconductor is robust to a normal (non-magnetic) impurity with small impurity strength or impurities with small concentration. While by increasing the size of impurity in a fixed host superconductor we also find a decrease $T_c$ of the host superconductor, the phase transition at the critical impurity strength is of zeroth order.

  11. Plasmas applied atomic collision physics, v.2

    CERN Document Server

    Barnett, C F

    1984-01-01

    Applied Atomic Collision Physics, Volume 2: Plasmas covers topics on magnetically confined plasmas. The book starts by providing the history of fusion research and describing the various approaches in both magnetically and inertially confined plasmas. The text then gives a general discussion of the basic concepts and properties in confinement and heating of a plasma. The theory of atomic collisions that result in excited quantum states, particularly highly ionized impurity atoms; and diverse diagnostic topics such as emission spectra, laser scattering, electron cyclotron emission, particle bea

  12. Characterization of a novel impurity in bulk drug of lisinopril by multidimensional NMR technique

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    During the routine impurity profile of lisinopril bulk drug by HPLC (high-performance liquid chromatography), a potential impurity was detected. Using multidimensional NMR (nuclear magnetic resonance) technique, the trace-level impurity was unambiguously identified to be 2-(-2-oxo-azocan-3-ylamino)-4-phenyl-butyric acid after isolation from lisinopril bulk drug by semi-preparative HPLC. Formation of the impurity was also discussed. To our knowledge, this is a novel impurity and not reported elsewhere.

  13. Effect of oxygen plasma treatment on anodic bonding

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Seung Woo; Choi, Woo Beom; Lee, Yun Hi; Ju, Byeong Kwon [Korea Institute of Science and Technology, Seoul (Korea, Republic of); Kim, Byong Ho [Korea Univ., Seoul (Korea, Republic of)

    2001-03-01

    Oxygen plasma surface treatment of silicon and glass was studied for improving the characteristics of anodic bonding. By using the sessile drop method, we confirmed that the surfaces activated by the oxygen plasma were rendered hydrophilic even at low r.f. power or short plasma exposure time. With increasing plasma power and exposure time the surface roughness was observed to increase. The oxygen plasma treatment was significantly efficient in reducing the impurities on the surface, which caused degradation in the bonding strength and the electrical property in interface. In the tensile test, the oxygen plasma treatment led to a higher bonding strength than the conventional anodic bonding method.

  14. Source Attribution of Cyanides Using Anionic Impurity Profiling, Stable Isotope Ratios, Trace Elemental Analysis and Chemometrics.

    Science.gov (United States)

    Mirjankar, Nikhil S; Fraga, Carlos G; Carman, April J; Moran, James J

    2016-02-02

    Chemical attribution signatures (CAS) for chemical threat agents (CTAs), such as cyanides, are being investigated to provide an evidentiary link between CTAs and specific sources to support criminal investigations and prosecutions. Herein, stocks of KCN and NaCN were analyzed for trace anions by high performance ion chromatography (HPIC), carbon stable isotope ratio (δ(13)C) by isotope ratio mass spectrometry (IRMS), and trace elements by inductively coupled plasma optical emission spectroscopy (ICP-OES). The collected analytical data were evaluated using hierarchical cluster analysis (HCA), Fisher-ratio (F-ratio), interval partial least-squares (iPLS), genetic algorithm-based partial least-squares (GAPLS), partial least-squares discriminant analysis (PLSDA), K nearest neighbors (KNN), and support vector machines discriminant analysis (SVMDA). HCA of anion impurity profiles from multiple cyanide stocks from six reported countries of origin resulted in cyanide samples clustering into three groups, independent of the associated alkali metal (K or Na). The three groups were independently corroborated by HCA of cyanide elemental profiles and corresponded to countries each having one known solid cyanide factory: Czech Republic, Germany, and United States. Carbon stable isotope measurements resulted in two clusters: Germany and United States (the single Czech stock grouped with United States stocks). Classification errors for two validation studies using anion impurity profiles collected over five years on different instruments were as low as zero for KNN and SVMDA, demonstrating the excellent reliability associated with using anion impurities for matching a cyanide sample to its factory using our current cyanide stocks. Variable selection methods reduced errors for those classification methods having errors greater than zero; iPLS-forward selection and F-ratio typically provided the lowest errors. Finally, using anion profiles to classify cyanides to a specific stock

  15. Occurrence of arsenic impurities in organoarsenics and animal feeds.

    Science.gov (United States)

    Yao, Lixian; Huang, Lianxi; He, Zhaohuan; Zhou, Changmin; Li, Guoliang

    2013-01-16

    Organoarsenics are widely used as excellent feed additives in animal production in the world. Roxarsone (ROX) and arsanilic acid (ASA) are two organoarsenics permitted to be used in China. We collected 146 animal feed samples to investigate the appearance of ROX, ASA, and potential metabolites, including 3-amino-4-hydroxyphenylarsonic acid (3-A-HPA), 4-hydroxyphenylarsonic acid (4-HPA), As(V), As(III), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) in feeds. The stability of ROX in both ROX additives and animal feeds was also examined. The results show that 25.4% of the 146 animal feeds contained organoarsenics, with average contents of ROX and ASA as 7.0 and 21.2 mg of As/kg, respectively. Unexpectedly, As(III) and MMA frequently occurred as As impurities in feeds bearing organoarsenics, with higher contents than organoarsenics in some samples. 3-A-HPA, 4-HPA, and DMA were not detected in all samples. ROX and As impurities in both ROX additives and feeds stayed unchanged in the shelf life. It suggests that As impurities in animal feeds bearing organoarsenics should generate from the use of organoarsenics containing As impurities. This constitutes the first report of As impurities in organoarsenics.

  16. Effects of impurities on crystal growth in fructose crystallization

    Science.gov (United States)

    Chu, Y. D.; Shiau, L. D.; Berglund, K. A.

    1989-10-01

    The influence of impurities on the crystallization of anhydrous fructose from aqueous solution was studied. The growth kinetics of fructose crystals in the fructose-water-glucose and fructose-water-difructose dianhydrides systems were investigated using photomicroscopic contact nucleation techniques. Glucose is the major impurity likely to be present in fructose syrup formed during corn wet milling, while several difructose dianhydrides are formed in situ under crystallization conditions and have been proposed as a cause in the decrease of overall yields. Both sets of impurities were found to cause inhibition of crystal growth, but the mechanisms responsible in each case are different. It was found that the presence of glucose increases the solubility of fructose in water and thus lowers the supersaturation of the solution. This is probably the main effect responsible for the decrease of crystal growth. Since the molecular structures of difructose dianhydrides are similar to that of fructose, they are probably "tailor-made" impurities. The decrease of crystal growth is probably caused by the incorporation of these impurities into or adsorption to the crystal surface which would accept fructose molecules in the orientation that existed in the difructose dianhydride.

  17. Adjacent stage impurity ratio in rare earth countercurrent extraction process

    Institute of Scientific and Technical Information of China (English)

    CHENG Fuxiang; WU Sheng; LIAO Chunsheng; YAN Chunhua

    2013-01-01

    Impurity components decrease stage by stage in a cascade of rare earth (RE) extraction separation,and adjacent stage impurity ratio (ASIR) which is defined as the ratio of an impurity's contents in the aqueous/organic phase of two adjacent stages can be used to evaluate the capacity of impurity removal for the two stages.On the basis of extraction equilibrium and mass balance,the ASIR in a two-component extraction separation was deducted and its simplified expressions were given for different process sections according to reasonable assumptions.The calculation simulation was then carried out to obtain the ASIR distribution in the cascade.The results showed that in both the extraction and scrubbing sections the ASIR principally increased with the decrease of the molar proportion of the impurity but along with a flat appearing in the purification zone located in the middle of the cascade.The ASIR intuitively exhibits the nmning status of RE extraction separation and purification,which could provide a theoretic guide for investigating the influence factors of RE extraction separation process in practical industry.

  18. EFFECT OF FUEL IMPURITIES ON FUEL CELL PERFORMANCE AND DURABILITY

    Energy Technology Data Exchange (ETDEWEB)

    Colon-Mercado, H.

    2010-09-28

    A fuel cell is an electrochemical energy conversion device that produces electricity during the combination of hydrogen and oxygen to produce water. Proton exchange membranes fuel cells are favored for portable applications as well as stationary ones due to their high power density, low operating temperature, and low corrosion of components. In real life operation, the use of pure fuel and oxidant gases results in an impractical system. A more realistic and cost efficient approach is the use of air as an oxidant gas and hydrogen from hydrogen carriers (i.e., ammonia, hydrocarbons, hydrides). However, trace impurities arising from different hydrogen sources and production increases the degradation of the fuel cell. These impurities include carbon monoxide, ammonia, sulfur, hydrocarbons, and halogen compounds. The International Organization for Standardization (ISO) has set maximum limits for trace impurities in the hydrogen stream; however fuel cell data is needed to validate the assumption that at those levels the impurities will cause no degradation. This report summarizes the effect of selected contaminants tested at SRNL at ISO levels. Runs at ISO proposed concentration levels show that model hydrocarbon compound such as tetrahydrofuran can cause serious degradation. However, the degradation is only temporary as when the impurity is removed from the hydrogen stream the performance completely recovers. Other molecules at the ISO concentration levels such as ammonia don't show effects on the fuel cell performance. On the other hand carbon monoxide and perchloroethylene shows major degradation and the system can only be recovered by following recovery procedures.

  19. Recirculation of Chilean copper smelting dust with high impurities contents to the smelting process

    Energy Technology Data Exchange (ETDEWEB)

    Sano, H.; Fujisawa, T. [Nagoya Univ., Nagoya (Japan). EcoTopia Science Inst.; Montenegro, V. [Nagoya Univ., Nagoya (Japan). Dept. of Materials Science and Engineering

    2007-07-01

    Dust generated during the copper smelting process is generally stabilized using hydrometallurgical methods as it contains high concentrations of arsenic. In this laboratory study, dust was recirculated during the smelting process in order to recover more copper and decrease dust emissions while recovering more copper. The behaviour of impurities and their influence on matte quality was also investigated. Industrial matte, flue dust, slag, and copper concentrates from a Chilean smelter were used as test materials. Dust recirculation tests were conducted in a simulated electric furnace. Off-gases were collected in a reaction tube, and the condensed volatile matter, slag, and matte phases were analyzed for their elemental content by inductively coupled plasma atomic emission spectrometry. The distribution of arsenic (As); antimony (Sb), bismuth (Bi), lead (Pb), and zinc (Zn) were investigated by varying the amounts of dust recirculating to the smelting stage with 21 per cent of the oxygen. Results showed that distributions of all analyzed elements increased with recirculation. It was concluded that copper can be recovered using the dust recirculation technique. However, impurities may limit the efficacy of the dust recirculation process. 6 refs., 3 tabs., 4 figs.

  20. Determination of Metal Impurities in Carbon Nanotubes Sampled Using Surface Wipes

    Directory of Open Access Journals (Sweden)

    Mary-Luyza Avramescu

    2016-01-01

    Full Text Available Residual metal impurities in carbon nanotubes (CNTs provide a means to distinguish CNT from non-CNT sources of elemental carbon in environmental samples. A practical and cost-effective analytical approach is needed to support routine surface monitoring of CNT metal tracers using wipe sampling. Wipe sampling for CNT metal tracers is considered a qualitative indicator of the presence of CNTs, not a quantitative exposure metric. In this study, two digestion approaches (microwave-assisted nitric acid/H2O2 digestion and ultrasonic nitric/HF acid digestion in conjunction with Inductively Coupled Plasma Mass Spectrometry (ICP-MS determination were evaluated for their ability to extract metal impurities from CNT particles captured on wipe substrates. Aliquots of different carbon nanotubes (including NIST 2483 single-wall CNT with and without GhostWipes™ (ASTM E-1792 compliant were used to compare the performance of the digestion methods. The microwave digestion method accommodated the bulky wipe sample and also eliminated potential ICP-MS signal interferences related to incomplete digestion. Although quantitative recoveries requiring lengthy multistep digestion protocols may be necessary in other applications, the near-total recoveries achieved in the present study for CNT catalyst elements were adequate for identifying surface contamination of CNTs in the workplace using wipe sampling.

  1. Nanoscale Conductive Channels in Silicon Whiskers with Nickel Impurity

    Science.gov (United States)

    Yatsukhnenko, Serhii; Druzhinin, Anatoly; Ostrovskii, Igor; Khoverko, Yuriy; Chernetskiy, Mukhajlo

    2017-01-01

    The magnetization and magnetoresistance of Si whiskers doped with to boron concentrations corresponding to the metal-insulator transition (2 × 1018 cm-3 ÷ 5 × 1018 cm-3) were measured at high magnetic fields up to 14 T in a wide temperature range 4.2-300 K. Hysteresis of the magnetic moment was observed for Si p-type whiskers with nickel impurity in a wide temperature range 4.2-300 K indicating a strong interaction between the Ni impurities and the possibility of a magnetic cluster creation. The introduction of Ni impurity in Si whiskers leads to appearance and increase of the magnitude of negative magnetoresistance up to 10% as well as to the decrease of the whisker resistivity in the range of hopping conductance at low temperatures. The abovementioned effects were explained in the framework of appearance of magnetic polarons leading to modification of the conductive channels in the subsurface layers of the whiskers.

  2. Removal of fluoride impurities from UF.sub.6 gas

    Science.gov (United States)

    Beitz, James V.

    1985-01-01

    A method of purifying a UF.sub.6 gas stream containing one or more metal fluoride impurities composed of a transuranic metal, transition metal or mixtures thereof, is carried out by contacting the gas stream with a bed of UF.sub.5 in a reaction vessel under conditions where at least one impurity reacts with the UF.sub.5 to form a nongaseous product and a treated gas stream, and removing the treated gas stream from contact with the bed. The nongaseous products are subsequently removed in a reaction with an active fluorine affording agent to form a gaseous impurity which is removed from the reaction vessel. The bed of UF.sub.5 is formed by the reduction of UF.sub.6 in the presence of UV light. One embodiment of the reaction vessel includes a plurality of UV light sources as tubes on which UF.sub.5 is formed.

  3. Extracting Impurity Locations using Scanning Capacitance Microscopy Measurements

    Directory of Open Access Journals (Sweden)

    AGHAEI, S.

    2016-08-01

    Full Text Available In this article we investigate the possibility to use scanning capacitance microscopy (SCM for the 2-D and 3-D "atomistic" dopant profiling of semiconductor materials. For this purpose, we first analyze the effects of random dopant fluctuations (RDF on SCM measurements with nanoscale probes and show that the discrete and random locations of dopant impurities significantly affect the differential capacitance measured in SCM experiments if the dimension of the probe is below 50 nm. Then, we present an algorithm to compute the x, y, and z coordinates of the ionized impurities in the semiconductor material using a set of SCM measurements. The algorithm is based on evaluating the doping sensitivity functions of the differential capacitance and uses a gradient-based iterative method to compute the locations of dopants. Finally, we discuss a standard simulation case and show that we are able to successfully retrieve the locations of the ionized impurities using the proposed algorithm.

  4. Polymeric efficiency in remove impurities during cottonseed biodiesel production

    Science.gov (United States)

    Lin, H. L.; Liang, Y. H.; Yan, J.; Lin, H. D.; Espinosa, A. R.

    2016-07-01

    This paper describes a new process for developing biodiesel by polymer from crude cottonseed oil. The study was conducted to examine the effectiveness of the alkali transesterification-flocculation-sedimentation process on fast glycerol and other impurities in the separation from biodiesel by using quaternary polyamine-based cationic polymers SL2700 and polyacylamide cationic polymer SAL1100. The settling velocity of glycerol and other impurities in biodiesel was investigated through settling test experiments; the quality of the biodiesel was investigated by evaluating the viscosity and density. The results revealed that SL2700, SAL1100 and their combination dramatically improved the settling velocity of glycerol and other impurities materials than traditional method. SL 2700 with molecular weight of 0.2 million Da and charge density of 50% then plus SAL1100 with molecular weight of 11 million Da and charge density of 10% induced observable particle aggregation with the best settling performance.

  5. An objective estimation of impurities in oil field stagnant waters

    Energy Technology Data Exchange (ETDEWEB)

    Abashev, R.G.; Runets, S.A.

    1984-01-01

    Studies and an analysis of published materials are used to establish the predominant role of the mechanical impurities of various origins covered by layers of the heavy components of petroleum products in reducing the injectivity of injection wells for injecting stagnant waters containing concretions. A method is proposed for determining the impurities in the oil field stagnant waters used for flooding; this method makes it possible to obtain more reliable results on the concentration of the concretions responsible in such conditions for the drop in the injectivity of the formation reservoirs. A comparative evaluation of the results from an analysis of the impurities determined by the existing method and the proposed method is given. This method is useful in oil field laboratories in the systematic quality control over injected waters.

  6. Macroscopic scattering of cracks initiated at single impurity atoms

    Science.gov (United States)

    Kermode, J. R.; Ben-Bashat, L.; Atrash, F.; Cilliers, J. J.; Sherman, D.; de Vita, A.

    2013-09-01

    Brittle crystals, such as coloured gems, have long been known to cleave with atomically smooth fracture surfaces, despite being impurity laden, suggesting that isolated atomic impurities do not generally cause cracks to deflect. Whether cracks can ever deviate when hitting an atomic defect, and if so how they can go straight in real brittle crystals, which always contain many such defects, is still an open question. Here we carry out multiscale molecular dynamics simulations and high-resolution experiments on boron-doped silicon, revealing that cracks can be deflected by individual boron atoms. The process, however, requires a characteristic minimum time, which must be less than the time spent by the crack front at the impurity site. Deflection therefore occurs at low crack speeds, leading to surface ridges which intensify when the boron-dopage level is increased, whereas fast-moving cracks are dynamically steered away from being deflected, yielding smooth cleavage surfaces.

  7. Moving impurity in an inhomogenous Bose-Einstein condensate

    Science.gov (United States)

    Mathew, Ranchu; Tiesinga, Eite

    2016-05-01

    We study the dynamics of a non-uniform Bose-Einstein condensate (BEC) under the influence of a moving weak point-like impurity. When the condensate density varies slowly compared to its healing length the critical velocity of the impurity, beyond which the condensate becomes unstable, can be calculated using the Local Density Approximation (LDA). This critical velocity corresponds to the smallest local sound speed. The LDA breaks down when the length scale of density variations is of the order of the healing length. We have calculated corrections to the critical velocity in this regime as an asymptotic expansion in the size of the BEC. We also discuss the experimental implications of our calculations by studying the stability of the atomic analogue of a Superconducting Quantum Interference Device (SQUID). The atom-SQUID consists of a BEC in a ring trap with rotating barrier. The impurity corresponds to imperfections in the ring trap.

  8. Impact of diffusion limited aggregates of impurities on nematic ordering

    Science.gov (United States)

    Harkai, S.; Ambrožič, M.; Kralj, S.

    2017-02-01

    We study the impact of random bond-type disorder on two-dimensional (2D) orientational ordering of nematic liquid crystal (LC) configurations. The lattice Lebwohl-Lasher pseudospin model is used to model orientational ordering perturbed by frozen-in rod-like impurities of concentration p exhibiting the isotropic orientational probability distribution. The impurities are either (i) randomly spatially distributed or (ii) form diffusion limited aggregation (DLA)-type patterns characterized by the fractal dimensions df, where we consider cases df ∼ 1.7 and df ∼ 1.9. The degree of orientational ordering is quantified in terms of the orientational pair correlation function G(r) . Simulations reveal that the DLA pattern imposed disorder has a significantly weaker impact for a given concentration of impurities. Furthermore, if samples are quenched from the isotropic LC phase, then the fractal dimension is relatively strongly imprinted on quantitative characteristics of G(r) .

  9. The effects of ambient impurities on the surface tension

    Directory of Open Access Journals (Sweden)

    Ponce-Torres A.

    2016-01-01

    Full Text Available A liquid bridge is a liquid column held captive between two coaxial and parallel solid disks. It is an excellent test bench where measuring the surface tension. In this paper, we used this fluid configuration to examine experimentally the effects of ambient impurities on the surface tension over time. For this purpose, the liquid bridge equilibrium shape was analyzed when the liquid bridge was surrounded by three environments: the uncontrolled ambient, and both air and argon encapsulated in a small glass cover. Ambient contamination produced a sharp decrease of the surface tension of ultra-pure water. The presence of an anionic surfactant in the free surface of an aqueous solution did not inhibit the action of impurities coming from the ambient. Impurities can influence the dynamical behavior of the free surface in flows dominated by the surface tension. Therefore, a careful control of that influence can be crucial in many applications of fluid mechanics.

  10. Interactions of structural defects with metallic impurities in multicrystalline silicon

    Energy Technology Data Exchange (ETDEWEB)

    McHugo, S.A.; Thompson, A.C. [Lawrence Berkeley National Lab., CA (United States); Hieslmair, H. [Univ. of California, Berkeley, CA (United States)] [and others

    1997-04-01

    Multicrystalline silicon is one of the most promising materials for terrestrial solar cells. It is critical to getter impurities from the material as well as inhibit contamination during growth and processing. Standard processing steps such as, phosphorus in-diffusion for p-n junction formation and aluminum sintering for backside ohmic contact fabrication, intrinsically possess gettering capabilities. These processes have been shown to improve L{sub n} values in regions of multicrystalline silicon with low structural defect densities but not in highly dislocated regions. Recent Deep Level Transient Spectroscopy (DLTS) results indirectly reveal higher concentrations of iron in highly dislocated regions while further work suggests that the release of impurities from structural defects, such as dislocations, is the rate limiting step for gettering in multicrystalline silicon. The work presented here directly demonstrates the relationship between metal impurities, structural defects and solar cell performance in multicrystalline silicon. Edge-defined Film-fed Growth (EFG) multicrystalline silicon in the as-grown state and after full solar cell processing was used in this study. Standard solar cell processing steps were carried out at ASE Americas Inc. Metal impurity concentrations and distributions were determined by use of the x-ray fluorescence microprobe (beamline 10.3.1) at the Advanced Light Source, Lawrence Berkeley National Laboratory. The sample was at atmosphere so only elements with Z greater than silicon could be detected, which includes all metal impurities of interest. Structural defect densities were determined by preferential etching and surface analysis using a Scanning Electron Microscope (SEM) in secondary electron mode. Mapped areas were exactly relocated between the XRF and SEM to allow for direct comparison of impurity and structural defect distributions.

  11. Current fluctuations in unconventional superconductor junctions with impurity scattering

    Science.gov (United States)

    Burset, Pablo; Lu, Bo; Tamura, Shun; Tanaka, Yukio

    2017-06-01

    The order parameter of bulk two-dimensional superconductors is classified as nodal if it vanishes for a direction in momentum space, or gapful if it does not. Each class can be topologically nontrivial if Andreev bound states are formed at the edges of the superconductor. Nonmagnetic impurities in the superconductor affect the formation of Andreev bound states and can drastically change the tunneling spectra for small voltages. Here, we investigate the mean current and its fluctuations for two-dimensional tunnel junctions between normal-metal and unconventional superconductors by solving the quasiclassical Eilenberger equation self-consistently, including the presence of nonmagnetic impurities in the superconductor. As the impurity strength increases, we find that superconductivity is suppressed for almost all order parameters since (i) at zero applied bias, the effective transferred charge calculated from the noise-current ratio tends to the electron charge e , and (ii) for finite bias, the current-voltage characteristics follows that of a normal-state junction. There are notable exceptions to this trend. First, gapful nontrivial (chiral) superconductors are very robust against impurity scattering due to the linear dispersion relation of their surface Andreev bound states. Second, for nodal nontrivial superconductors, only px-wave pairing is almost immune to the presence of impurities due to the emergence of odd-frequency s -wave Cooper pairs near the interface. Due to their anisotropic dependence on the wave vector, impurity scattering is an effective pair-breaking mechanism for the remaining nodal superconductors. All these behaviors are neatly captured by the noise-current ratio, providing a useful guide to find experimental signatures for unconventional superconductivity.

  12. Source Attribution of Cyanides using Anionic Impurity Profiling, Stable Isotope Ratios, Trace Elemental Analysis and Chemometrics

    Energy Technology Data Exchange (ETDEWEB)

    Mirjankar, Nikhil S.; Fraga, Carlos G.; Carman, April J.; Moran, James J.

    2016-01-08

    Chemical attribution signatures (CAS) for chemical threat agents (CTAs) are being investigated to provide an evidentiary link between CTAs and specific sources to support criminal investigations and prosecutions. In a previous study, anionic impurity profiles developed using high performance ion chromatography (HPIC) were demonstrated as CAS for matching samples from eight potassium cyanide (KCN) stocks to their reported countries of origin. Herein, a larger number of solid KCN stocks (n = 13) and, for the first time, solid sodium cyanide (NaCN) stocks (n = 15) were examined to determine what additional sourcing information can be obtained through anion, carbon stable isotope, and elemental analyses of cyanide stocks by HPIC, isotope ratio mass spectrometry (IRMS), and inductively coupled plasma optical emission spectroscopy (ICP-OES), respectively. The HPIC anion data was evaluated using the variable selection methods of Fisher-ratio (F-ratio), interval partial least squares (iPLS), and genetic algorithm-based partial least squares (GAPLS) and the classification methods of partial least squares discriminate analysis (PLSDA), K nearest neighbors (KNN), and support vector machines discriminate analysis (SVMDA). In summary, hierarchical cluster analysis (HCA) of anion impurity profiles from multiple cyanide stocks from six reported country of origins resulted in cyanide samples clustering into three groups: Czech Republic, Germany, and United States, independent of the associated alkali metal (K or Na). The three country groups were independently corroborated by HCA of cyanide elemental profiles and corresponded to countries with known solid cyanide factories. Both the anion and elemental CAS are believed to originate from the aqueous alkali hydroxides used in cyanide manufacture. Carbon stable isotope measurements resulted in two clusters: Germany and United States (the single Czech stock grouped with United States stocks). The carbon isotope CAS is believed to

  13. Modeling Electronegative Impurity Concentrations in Liquid Argon Detectors

    Science.gov (United States)

    Tang, Wei; Li, Yichen; Thorn, Craig; Qian, Xin

    2017-01-01

    Achieving long electron lifetime is crucial to reach the high performance of large Liquid Argon Time Projection Chamber (LArTPC) envisioned for next generation neutrino experiments. We have built up a quantitative model to describe the impurity distribution and transportation in a cryostat. Henrys constants of Oxygen and water, which describe the partition of impurities between gas argon and liquid argon, have been deduced through this model with the measurements in BNL 20-L LAr test stand. These results indicate the importance of the gas purification system and prospects on large LArTPC detectors will be discussed.

  14. Neutrality point of graphene with coplanar charged impurities.

    Science.gov (United States)

    Fogler, Michael M

    2009-12-04

    The ground state and the transport properties of graphene subject to the potential of in-plane charged impurities are studied. The screening of the impurity potential is shown to be nonlinear, producing a fractal structure of electron and hole puddles. Statistical properties of this density distribution as well as the charge compressibility of the system are calculated in the leading-log approximation. The conductivity depends logarithmically on alpha, the dimensionless strength of the Coulomb interaction. The theory is asymptotically exact when alpha is small, which is the case for graphene on a substrate with a high dielectric constant.

  15. Impurity centers in LiF:Cu{sup +} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Nepomnyashchikh, A I; Shalaev, A A; Subanakov, A K; Paklin, A S; Bobina, N S; Myasnikova, A S; Shendrik, R, E-mail: alshal@igc.irk.ru

    2010-11-15

    The single crystals LiF with copper impurity were grown by Czochralski method. The concentrations of Cu in the crystals were 0,0004-0,002%. In order to determine a copper valence impurity, measurements of the ESR, emission, excitation and absorption spectra were performed. We found emission peak at 410 nm and excitation peak at 250 nm. In agreement with reference, these peaks point to presence of Cu{sup +} in our samples. The mechanisms of capture and recombination providing process of thermoluminescence were recognized.

  16. On exchange interaction between shallow impurity centers in diluted semiconductors.

    Science.gov (United States)

    Krotkov, Pavel; Gor'kov, Lev

    2003-03-01

    We generalize the method developed in [1,2] to obtain asymptotically exact expressions for the exchange splitting in semiconductors of the levels of carriers localized on shallow impurities at small impurity concentrations (large inter-center separations). Our approach takes into account degeneracy inherent to shallow centers in most semiconductors. We also consider the effects of spin-orbital interaction and of an external magnetic field. [1] L.P. Gor'kov and L.P. Pitaevskii, Dokl. Akad. Nauk SSSR 151, 822 (1963) [Sov. Phys. Dokl. 8, 788 (1964)]. [2] C. Herring and M. Flicker, Phys. Rev. 134, A362 (1964)].

  17. Critical quasiparticles in single-impurity and lattice Kondo models

    Science.gov (United States)

    Vojta, M.; Bulla, R.; Wölfle, P.

    2015-07-01

    Quantum criticality in systems of local moments interacting with itinerant electrons has become an important and diverse field of research. Here we review recent results which concern (a) quantum phase transitions in single-impurity Kondo and Anderson models and (b) quantum phase transitions in heavy-fermion lattice models which involve critical quasiparticles. For (a) the focus will be on impurity models with a pseudogapped host density of states and their applications, e.g., in graphene and other Dirac materials, while (b) is devoted to strong-coupling behavior near antiferromagnetic quantum phase transitions, with potential applications in a variety of heavy-fermion metals.

  18. Nonlinear excitations in two-dimensional molecular structures with impurities

    DEFF Research Database (Denmark)

    Gaididei, Yuri Borisovich; Rasmussen, Kim; Christiansen, Peter Leth

    1995-01-01

    We study the nonlinear dynamics of electronic excitations interacting with acoustic phonons in two-dimensional molecular structures with impurities. We show that the problem is reduced to the nonlinear Schrodinger equation with a varying coefficient. The latter represents the influence of the imp......We study the nonlinear dynamics of electronic excitations interacting with acoustic phonons in two-dimensional molecular structures with impurities. We show that the problem is reduced to the nonlinear Schrodinger equation with a varying coefficient. The latter represents the influence...... excitations. Analytical results are in good agreement with numerical simulations of the nonlinear Schrodinger equation....

  19. Virmid: accurate detection of somatic mutations with sample impurity inference.

    Science.gov (United States)

    Kim, Sangwoo; Jeong, Kyowon; Bhutani, Kunal; Lee, Jeong; Patel, Anand; Scott, Eric; Nam, Hojung; Lee, Hayan; Gleeson, Joseph G; Bafna, Vineet

    2013-08-29

    Detection of somatic variation using sequence from disease-control matched data sets is a critical first step. In many cases including cancer, however, it is hard to isolate pure disease tissue, and the impurity hinders accurate mutation analysis by disrupting overall allele frequencies. Here, we propose a new method, Virmid, that explicitly determines the level of impurity in the sample, and uses it for improved detection of somatic variation. Extensive tests on simulated and real sequencing data from breast cancer and hemimegalencephaly demonstrate the power of our model. A software implementation of our method is available at http://sourceforge.net/projects/virmid/.

  20. Flat panel display - Impurity doping technology for flat panel displays

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Toshiharu [Advanced Technology Planning, Sumitomo Eaton Nova Corporation, SBS Tower 9F, 10-1, Yoga 4-chome, Setagaya-ku, 158-0097 Tokyo (Japan)]. E-mail: suzuki_tsh@senova.co.jp

    2005-08-01

    Features of the flat panel displays (FPDs) such as liquid crystal display (LCD) and organic light emitting diode (OLED) display, etc. using low temperature poly-Si (LTPS) thin film transistors (TFTs) are briefly reviewed comparing with other FPDs. The requirements for fabricating TFTs used for high performance FPDs and system on glass (SoG) are addressed. This paper focuses on the impurity doping technology, which is one of the key technologies together with crystallization by laser annealing, formation of high quality gate insulator and gate-insulator/poly-Si interface. The issues to be solved in impurity doping technology for state of the art and future TFTs are clarified.

  1. Microstructure and Properties of Plasma Spraying Boron Carbide Coating

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Microstructure of plasma spray boron carbide coating was studied by SEM and TEM. Its physical,mechanical and electrical properties were measured. The results showed that high microhardness,modulus and Iow porosity of B4C coating were manufactured by plasma spray. It was lamellar packing and dense. The B4C coating examined here contained two principal structures and two impurity phase besides major phase. The relatively small value of Young′s modulus, comparing with that of the bulk materials, is explained by porosity. The Fe impurity phase could account for the relatively high electrical conductivity of boron carbide coating by comparing with the general boron carbide materials.

  2. Statistical analysis of variations in impurity ion heating at reconnection events in the Madison Symmetric Torus

    Energy Technology Data Exchange (ETDEWEB)

    Cartolano, M. S.; Craig, D., E-mail: darren.craig@wheaton.edu [Wheaton College, Wheaton, Illinois 60187 (United States); Den Hartog, D. J.; Kumar, S. T. A.; Nornberg, M. D. [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Center for Magnetic Self-Organization in Laboratory and Astrophysical Plasmas, Madison, Wisconsin 53706 (United States)

    2014-01-15

    The connection between impurity ion heating and other physical processes in the plasma is evaluated by studying variations in the amount of ion heating at reconnection events in the Madison Symmetric Torus (MST). Correlation of the change in ion temperature with individual tearing mode amplitudes indicates that the edge-resonant modes are better predictors for the amount of global ion heating than the core-resonant modes. There is also a strong correlation between ion heating and current profile relaxation. Simultaneous measurements of the ion temperature at different toroidal locations reveal, for the first time, a toroidal asymmetry to the ion heating in MST. These results present challenges for existing heating theories and suggest a stronger connection between edge-resonant tearing modes, current profile relaxation, and ion heating than has been previously thought.

  3. Effects of impurity transport and melt layer motion to the tungsten wall erosion during anomaly events

    Energy Technology Data Exchange (ETDEWEB)

    Ibano, K., E-mail: kibano@eei.eng.osaka-u.ac.jp; Tsutsui, T.; Lang, T.L.; Togo, S.; Ogawa, Y.

    2015-08-15

    Developing designs of future fusion devices, safety and soundness of the rector at anomaly events must be ensured. A computational approach is being taken by developing a homegrown integrated reactor simulation code and analyzing a loss-of-cooling-gas-puff accident (LCGA). This code currently includes simple plasma, edge, and wall models. In this study, models for the tungsten transport and melt layer motion was added and used for the analysis. It was found that this accident results significant erosion of the wall while impurities from the wall would contribute the radiation cooling for the intense heat flux. However, these effects strongly depend on an uncertain parameter of the tungsten transport as well as the tungsten melt layer motion. Thus, parametric survey for these uncertain quantities were taken and discussed.

  4. Moderation of target loads using fuelling and impurity seeding on JET

    Energy Technology Data Exchange (ETDEWEB)

    Maddison, G., E-mail: geoff.maddison@ccfe.ac.uk [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Giroud, C. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); McCormick, K. [Max-Planck IPP, EURATOM Association, D-85748 Garching (Germany); Alonso, A. [Asociacion EURATOM-CIEMAT, Laboratorio Nacional de Fusion (Spain); Alper, B.; Andrew, Y.; Arnoux, G. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Belo, P. [IPFN, EURATOM-IST Associacao, 1096 Lisbon (Portugal); Beurskens, M.; Boboc, A.; Brett, A. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Brezinsek, S. [IEF-Plasmaphysik, Forschungszentrum Juelich, Association EURATOM-FZJ, Juelich (Germany); Brix, M. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Coffey, I. [Queen' s University Belfast, University Road, Belfast BT7 1NN, Northern Ireland (United Kingdom); Luna, E. de la [Asociacion EURATOM-CIEMAT, Laboratorio Nacional de Fusion (Spain); Devaux, S. [Max-Planck IPP, EURATOM Association, D-85748 Garching (Germany); Vries, P. de [FOM IPP Rijnhuizen, Association EURATOM-FOM, 3430 BE NIEUWEGEIN (Netherlands); Devynck, P. [Association EURATOM-CEA, IRFM, F-13108 St Paul lez Durance (France); Eich, T. [Max-Planck IPP, EURATOM Association, D-85748 Garching (Germany); Felton, R. [EURATOM/CCFE Fusion Association, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)

    2011-08-01

    Operation with an all metal, ITER-like wall on JET is scheduled from 2011. Adaptation particularly of baseline ELMy H-mode (q{sub 95} {approx} 3.5) to the new exhaust constraints involved has been explored by systematic scans of deuterium fuelling and seeding with extrinsic impurities neon or nitrogen. Peak heat load between ELMs on the outboard target can be strongly reduced by fuelling (recycling), and approach detachment with either seed species, for only {approx}10% loss of normalised energy confinement. Simultaneously, normalised plasma density and total radiation averaged between ELMs are not simply increased, but at stronger fuelling can actually fall with increasing seeding, indicating some redistribution of efflux power temporally and spatially. At highest nitrogen seeding, ELMs can also be mitigated, even while the electron pedestal and confinement are largely preserved. Charge-exchange recombination spectroscopy indicates a substitution of intrinsic carbon with extrinsic species.

  5. Spectroscopic system for impurity measurements in the TJ-1 Tokamak of JEN; Un sistema espectroscopico para medidas de impurezas en el Tokamak TJ-1 de la JEN

    Energy Technology Data Exchange (ETDEWEB)

    Navas, G.; Zurro, B.

    1982-07-01

    we describe a spectroscopic system with spatial resolution capability that has been configured for plasma diagnostic in the TJ-1 Tokamak of JEN. The experimental system, based on a one meter monochromator, has been absolutely calibrated using a tungsten-halogen lamp. The calibration procedures and the absolute spectral sensitivity are presented as well as its dependence with the polarization. A simplified spectroscopic model of the radiation emitted by the intrinsic plasma impurities (C, 0, . . . ) has been developed. A one dimensional model of the temporal evolution of various ionization stages in coronal equilibrium is used to predict the electron temperature and impurity concentration. This model has been applied to experimental data from several Tokamaks. (Author) 23 refs.

  6. Electronic and Shallow Impurity States in Semiconductor Heterostructures Under an Applied Electric Field

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hai-Yang; GU Shi-Wei; SHI Yao-Ming

    2005-01-01

    With the use of variational method to solve the effective mass equation, we have studied the electronic and shallow impurity states in semiconductor heterostructures under an applied electric field. The electron energy levels are calculated exactly and the impurity binding energies are calculated with the variational approach. It is found that the behaviors of electronic and shallow impurity states in heterostructures under an applied electric field are analogous to that of quantum wells. Our results show that with the increasing strength of electric field, the electron confinement energies increase, and the impurity binding energy increases also when the impurity is on the surface, while the impurity binding energy increases at first, to a peak value, then decreases to a value which is related to the impurity position when the impurity is away from the surface. In the absence of electric field, the result tends to the Levine's ground state energy (-1/4 effective Rydberg) when the impurity is on the surface, and the ground impurity binding energy tends to that in the bulk when the impurity is far away from the surface. The dependence of the impurity binding energy on the impurity position for different electric field is also discussed.

  7. Multi-species impurity granule injection and mass deposition projections in NSTX-U discharges

    Science.gov (United States)

    Lunsford, R.; Bortolon, A.; Roquemore, A. L.; Mansfield, D. K.; Jaworski, M. A.; Kaita, R.; Maingi, R.; Nagy, A.

    2017-07-01

    By employing a neutral gas shielding (NGS) model to characterize impurity granule injection, the ablation rates for three different species of granule: lithium, boron, and carbon, are determined. Utilizing the duration of ablation events recorded on experiments performed at DIII-D to calibrate the NGS model, we quantify the ablation rate with respect to the plasma density profile. The species-specific granule shielding constant is then used to model granule ablation within NSTX-U discharges. Simulations of 300, 500 and 700 micron diameter granules injected at 50 m s-1 are presented for NSTX-U L-mode type plasmas, as well as H-mode discharges with low natural ELM frequency. Additionally, ablation calculations of 500 micron granules of each species are presented at velocities ranging from 50-150 m s-1. In H-mode discharges these simulations show that the majority of the injected granule is ablated within or just past the edge steep gradient region. At this radial position, the perturbation to the background plasma generated by the ablating granule can lead to conditions advantageous for the rapid triggering of ELM crashes.

  8. Lipopolysaccharide contamination in intradermal DNA vaccination : toxic impurity or adjuvant?

    NARCIS (Netherlands)

    Berg, J.H. van den; Quaak, S.G.L.; Beijnen, J.H.; Hennink, W.E.; Storm, G.; Schumacher, T.N.; Haanen, J.B.A.G.; Nuijen, B.

    2010-01-01

    Purpose: Lipopolysaccharides (LPS) are known both as potential adjuvants for vaccines and as toxic impurity in pharmaceutical preparations. The aim of this study was to assess the role of LPS in intradermal DNA vaccination administered by DNA tattooing. Method: Micewere vaccinated with a model DNA v

  9. Determination of Impurity Elements in Pure Cerium Oxide Product

    Institute of Scientific and Technical Information of China (English)

    Li Peizhong; Chen Limin; Li Jie

    2004-01-01

    Determination of the rare earth impurity in pure cerium oxide is done by ICP-MS.The interference and other factors which affect analytical results were discussed.The accuracy are between 0.81% ~ 11.98% and the recoveries of standard addition are 96% ~ 112.5%.This method can meet the demand for product inspection.

  10. Effect of sample preparation on charged impurities in graphene substrates

    Science.gov (United States)

    Burson, K. M.; Dean, C. R.; Watanabe, K.; Taniguchi, T.; Hone, J.; Kim, P.; Cullen, W. G.; Fuhrer, M. S.

    2013-03-01

    The mobility of graphene as fabricated on SiO2 has been found to vary widely depending on sample preparation conditions. Additionally, graphene mobility on SiO2 appears to be limited to ~20,000 cm2/Vs, likely due to charged impurities in the substrate. Here we present a study of the effect of fabrication procedures on substrate charged impurity density (nimp) utilizing ultrahigh-vacuum Kelvin probe force microscopy. We conclude that even minimal SEM exposure, as from e-beam lithography, induces an increased impurity density, while heating reduces the number of charges for sample substrates which already exhibit a higher impurity density. We measure both SiO2 and h-BN and find that all nimp values observed for SiO2 are higher than those observed for h-BN; this is consistent with the observed improvement in mobility for graphene devices fabricated on h-BN over those fabricated on SiO2 substrates. This work was supported by the US ONR MURI program, and the University of Maryland NSF-MRSEC under Grant No. DMR 05-20471.

  11. Strong impact of impurity bands on domain formation in superlattices

    DEFF Research Database (Denmark)

    Wacker, Andreas; Jauho, Antti-Pekka

    1998-01-01

    The formation of electric field domains in doped semiconductor superlattices is described within a microscopic model. Due to the presence of impurity bands in low-doped samples the current-voltage characteristic is essentially different compared to medium-doped samples. (C) 1998 Published by Else...

  12. Lipopolysaccharide contamination in intradermal DNA vaccination : toxic impurity or adjuvant?

    NARCIS (Netherlands)

    Berg, J.H. van den; Quaak, S.G.L.; Beijnen, J.H.; Hennink, W.E.; Storm, G.; Schumacher, T.N.; Haanen, J.B.A.G.; Nuijen, B.

    Purpose: Lipopolysaccharides (LPS) are known both as potential adjuvants for vaccines and as toxic impurity in pharmaceutical preparations. The aim of this study was to assess the role of LPS in intradermal DNA vaccination administered by DNA tattooing. Method: Micewere vaccinated with a model DNA

  13. Recovery of surfaces from impurity poisoning during crystal growth

    Science.gov (United States)

    Land, Terry A.; Martin, Tracie L.; Potapenko, Sergey; Palmore, G. Tayhas; de Yoreo, James J.

    1999-06-01

    Growth and dissolution of crystal surfaces are central to processes as diverse as pharmaceutical manufacturing,, corrosion, single-crystal production and mineralization in geochemical and biological environments,. Impurities are either unavoidable features of these processes or intentionally introduced to modify the products. Those that act as inhibiting agents induce a so-called `dead zone', a regime of low supersaturation where growth ceases. Models based on the classic theory of Cabrera and Vermilyea explain behaviour near the dead zone in terms of the pinning of elementary step motion by impurities,. Despite general acceptance of this theory, a number of commonly investigated systems exhibit behaviour not predicted by such models. Moreover, no clear microscopic picture of impurity-step interactions currently exists. Here we use atomic force microscopy to investigate the potassium dihydrogen phosphate {100} surface as it emerges from the dead zone. We show that traditional models are not able to account for the behaviour of this system because they consider only elementary steps, whereas it is the propagation of macrosteps (bunches of monolayer steps) that leads to resurrection of growthout of the dead zone. We present a simple physical model of this process that includes macrosteps and relates characteristics of growth near the dead zone to the timescale for impurity adsorption.

  14. Neoclassical transport in density pedestals with non-trace impurities

    Science.gov (United States)

    Buller, Stefan; Pusztai, Istvan; Landreman, Matt

    2016-10-01

    We study neoclassical transport in steady-state density pedestals with non-trace impurities using the Eulerian δf code Perfect, with an emphasis on radially global effects and the effects of impurities. To properly describe transport in a tokamak pedestal, radial coupling must be included, which strongly affects the transport. We find that radial coupling reduces the pedestal heat flux compared to local predictions. Furthermore, the influence of the pedestal persists several orbit widths into the core. The electron flux is significant in the pedestal, and global neoclassical transport is not intrinsically ambipolar. Thus, the impurity flux is not simply opposing the ion flux. The resulting radial current gives a torque that is balanced by a non-negligible radial transport of toroidal momentum. The effective Prandtl number is comparable to typical turbulent values in the core (0.1 - 0.3), and is sensitive to the impurity content. Global effects have a strong contribution to the poloidal flows of low- Z ions, which give rise to larger in-out flow asymmetries. Supported by the INCA Grant of Vetenskapsrådet (Dnr. 330-2014-6313). ML is supported by the USDoE Grants DEFG0293ER54197 and DEFC0208ER54964. The simulations used computational resources of Hebbe at C3SE (C3SE2016-1-10 & SNIC2016-1-161).

  15. Charged impurity-induced scatterings in chemical vapor deposited graphene

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ming-Yang; Tang, Chiu-Chun [Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Ling, D. C. [Department of Physics, Tamkang University, Tamsui Dist., New Taipei 25137, Taiwan (China); Li, L. J. [Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 11529, Taiwan (China); Chi, C. C.; Chen, Jeng-Chung [Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu 30013, Taiwan (China)

    2013-12-21

    We investigate the effects of defect scatterings on the electric transport properties of chemical vapor deposited (CVD) graphene by measuring the carrier density dependence of the magneto-conductivity. To clarify the dominant scattering mechanism, we perform extensive measurements on large-area samples with different mobility to exclude the edge effect. We analyze our data with the major scattering mechanisms such as short-range static scatters, short-range screened Coulomb disorders, and weak-localization (WL). We establish that the charged impurities are the predominant scatters because there is a strong correlation between the mobility and the charge impurity density. Near the charge neutral point (CNP), the electron-hole puddles that are induced by the charged impurities enhance the inter-valley scattering, which is favorable for WL observations. Away from the CNP, the charged-impurity-induced scattering is weak because of the effective screening by the charge carriers. As a result, the local static structural defects govern the charge transport. Our findings provide compelling evidence for understanding the scattering mechanisms in graphene and pave the way for the improvement of fabrication techniques to achieve high-quality CVD graphene.

  16. Hyperfine Interactions, Magnetic Impurities and Ordering in Praseodymium

    DEFF Research Database (Denmark)

    Bjerrum Møller, Hans; Jensen, J. Z.; Wulff, M.;

    1982-01-01

    The antiferromagnetic ordering in Pr due to the coupling of the 4f electronic system to the nuclei and to magnetic Nd impurities has been studied by neutron diffraction. A pure monocrystal of Pr develops true long-range order at about 50-60 mK. The ordering in both this crystal and a PrNd alloy i...

  17. Nonlinearity and disorder: Classification and stability of nonlinear impurity modes

    DEFF Research Database (Denmark)

    Sukhorukov, Andrey A.; Kivshar, Yuri S.; Bang, Ole

    2001-01-01

    We study the effects produced by competition of two physical mechanisms of energy localization in inhomogeneous nonlinear systems. As an example, we analyze spatially localized modes supported by a nonlinear impurity in the generalized nonlinear Schrödinger equation and describe three types of no...

  18. Dynamic and Impure Perovskite Structured Metal Oxide Surfaces

    DEFF Research Database (Denmark)

    Hansen, Karin Vels; Norrman, Kion; Traulsen, Marie Lund

    2017-01-01

    on the electrode surfaces. An experimental test of the suggestion that the segregation might happen in the vacuum in the analysis equipment gave a negative result. Formation of particles containing significant amounts of S and Cr from segregation of the trace impurities in the acquired powders were observed...

  19. Analysis of Radioactive Nuclide Impurities in Potassium Pertechnetate

    Institute of Scientific and Technical Information of China (English)

    WANG; Xiu-feng; CHEN; Ming; SUN; Hong-qing; SUN; Xiao-yi; MA; Peng; DING; You-qian

    2015-01-01

    99Tc is a pure beta radionuclide,its half-life is 2.111×105 a,and is widely used in nuclear medicine.Potassium pertechnetate is an important material of technetium(99Tc)methylene diphosphate injection.In order to determinate the radioactive impurity content,this study established

  20. Impurity and trace tritium transport in tokamak edge turbulence

    DEFF Research Database (Denmark)

    Naulin, V.

    2005-01-01

    and locally exceeds its initial values due to the compressibility of the flow. An approximate decomposition of the impurity flux into a diffusive part and an effective convective part (characterized by a pinch velocity) is performed and a net inward pinch effect is recovered. The pinch velocity is explained...

  1. Effect of impurities in description of surface nanobubbles

    NARCIS (Netherlands)

    Das, Siddhartha; Snoeijer, Jacco H.; Lohse, Detlef

    2010-01-01

    Surface nanobubbles emerging at solid-liquid interfaces of submerged hydrophobic surfaces show extreme stability and very small (gas-side) contact angles. In a recent paper Ducker [ W. A. Ducker Langmuir 25 8907 (2009)]. conjectured that these effects may arise from the presence of impurities at the

  2. Effect of Impurities in Description of Surface Nanobubbles

    CERN Document Server

    Das, Siddhartha; Lohse, Detlef

    2010-01-01

    Surface nanobubbles emerging at solid-liquid interfaces of submerged hydrophobic surfaces show extreme stability and very small (gas-side) contact angles. In a recent study Ducker (W. A. Ducker, Langmuir 25, 8907 (2009).) conjectured that these effects may arise from the presence of impurities at the air-water interface of the nanobubbles. In this paper we present a quantitative analysis of this hypothesis by estimating the dependence of the contact angle and the Laplace pressure on the fraction of impurity coverage at the liquid-gas interface. We first develop a general analytical framework to estimate the effect of impurities (ionic or non-ionic) in lowering the surface tension of a given air-water interface. We then employ this model to show that the (gas-side) contact angle and the Laplace pressure across the nanobubbles indeed decrease considerably with an increase in the fractional coverage of the impurities, though still not sufficiently small to account for the observed surface nanobubble stability. T...

  3. Impurities in silicon and their impact on solar cell performance

    NARCIS (Netherlands)

    Coletti, Gianluca

    2011-01-01

    Photovoltaic conversion of solar energy is a rapidly growing technology. More than 80% of global solar cell production is currently based on silicon. The aim of this thesis is to understand the complex relation between impurity content of silicon starting material (“feedstock”) and the resulting sol

  4. 40 CFR 158.340 - Discussion of formation of impurities.

    Science.gov (United States)

    2010-07-01

    ... its use. (v) Post-production reactions between the ingredients in the product. (vi) The possible... between the active ingredient and the production equipment. (4) Post-production reactions between any of... production or formulation process. If the applicant has reason to believe that an impurity that EPA would...

  5. Specific Activity and Impurities in Irradiated Natural Nickel Target

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    In this paper, the specific activity of the 63Ni which is produced by irradiating natural nickel in a nuclear reactor is calculated. And in the 1 g irradiated natural nickel target, the species of the key impurity nuclides were analyzed,

  6. Controlled samples for silicon defect and impurity studies

    Energy Technology Data Exchange (ETDEWEB)

    Ciszek, T.F. [National Renewable Energy Lab., Golden, CO (United States)

    1995-08-01

    Because of the diverse defects and impurities that are present in any given sample of silicon material, it can be extremely difficult to conduct a controlled experiment to study the influence of any particular defect or impurity on photovoltaic properties such as minority charge carrier lifetime {tau} or solar cell efficiency q. For example, the influence of iron may be different if boron is present, or the influence of silicon self interstitial clusters may be different if oxygen is present. It thus becomes important to conduct such studies on controlled samples where the influence of secondary effects is minimized. At NREL, over the past several years, we have focused on using the high-purity float-zone (FZ) growth method to obtain controlled samples. Because the silicon melt is not in contact with a container, and no heated components are in the growth region, very high purities and low defect levels can be achieved in baseline material. The baseline can be controllably perturbed by introduction of specific defects or impurities. The chart shown below lists some of the types of defect and impurity. combinations that can be studied in this way. The boxes marked with an {open_quotes}x{close_quotes} represent combinations we have studied to some extent.

  7. Substitutional 4d and 5d impurities in graphene.

    Science.gov (United States)

    Alonso-Lanza, Tomás; Ayuela, Andrés; Aguilera-Granja, Faustino

    2016-08-21

    We describe the structural and electronic properties of graphene doped with substitutional impurities of 4d and 5d transition metals. The adsorption energies and distances for 4d and 5d metals in graphene show similar trends for the later groups in the periodic table, which are also well-known characteristics of 3d elements. However, along earlier groups the 4d impurities in graphene show very similar adsorption energies, distances and magnetic moments to the 5d ones, which can be related to the influence of the 4d and 5d lanthanide contraction. Surprisingly, within the manganese group, the total magnetic moment of 3 μB for manganese is reduced to 1 μB for technetium and rhenium. We find that compared with 3d elements, the larger size of the 4d and 5d elements causes a high degree of hybridization with the neighbouring carbon atoms, reducing spin splitting in the d levels. It seems that the magnetic adjustment of graphene could be significantly different if 4d or 5d impurities are used instead of 3d impurities.

  8. Stability-Indicating UPLC Method for Tramadol HCl Impurities in the Tramadol Injection after Dilution by Infusion Fluids (5% Dextrose and 0.9% Sodium Chloride).

    Science.gov (United States)

    Binnor, Anil K; Mukkanti, Khagga; Suryanarayana, Mulukutla V; Roy, Sunilendu B

    2013-01-01

    A novel, rapid, and sensitive ultra-performance liquid chromatography (UPLC) method has been developed and validated as per ICH guidelines for the determination of tramadol HCl impurities in the tramadol HCl injection after reconstitution by infusion fluids (5% dextrose and 0.9% sodium chloride). The tramadol HCl injection is for the treatment of patients with moderate-to-severe pain. The stability of the reconstituted solution is critical before intravenous injection. The literature search resulted in few published articles on assays of tramadol in infusion fluids by conventional HPLC. No attempts have yet been made to determine the impurities in infusion fluids, as the concentration of tramadol after reconstitution is extremely low (0.4 mg/mL) and that of impurities is even lower. The proposed method is novel as it allows the quantitation of the impurities of tramadol HCl and is based on modern chromatographic techniques like UPLC. The method was developed using the Waters Acquity BEH C18 column with a mobile phase consisting of a gradient mixture of solvent A (trifluroacetic acid buffer) and solvent B (methanol: acetonitrile). The model stability study was designed by diluting the tramadol HCl injection in the 5% dextrose injection and 0.9% sodium chloride injection. Each mixture was kept under storage at room temperature (25 ± 2°C) for testing at initial, 2, 4, 8, 12, 18 & 24 hours. The validation study illustrates that the proposed method is suitable for the determination of tramadol and its impurities. The proposed method makes use of the LC-MS-compatible mobile phase. It can be useful for the determination of tramadol HCl and its impurities in plasma samples and other pharmaceutical dosage forms.

  9. Identification, synthesis, isolation and characterization of new impurity in metoprolol tartrate tablets.

    Science.gov (United States)

    Reddy, R Buchi; More, Kishor R; Gupta, Leena; Jha, Mukesh S; Magar, Laki

    2016-01-05

    A new unknown impurity was observed in accelerated stability studies of Metoprolol tartrate tablets. This impurity has been identified, synthesized and characterized through different spectral studies and confirmed as an adduct of lactose and Metoprolol formed by Maillard reaction.

  10. Characterization of Plasma Gun with TiH2/C60 Cartridge for Disruption Mitigation in Tokamaks

    Science.gov (United States)

    Bogatu, I. N.; Thompson, J. R.; Galkin, S. A.; Kim, J. S.; HyperV Technologies Corp. Team

    2011-10-01

    Impurity injection for disruption mitigation in tokamaks must be faster than growth time of plasma instabilities, requires sufficient mass to get critical electron density, high penetrability, and large assimilation fraction in the core plasma, with rapid impurity redistribution over the whole plasma. FAR-TECH, Inc. proposed the innovative idea to use hyper-velocity (>30 km/s), high-density (>1023 m-3) C60/C plasma jets with high ram pressure to deliver the impurity mass in plasma accelerator. We report the complete characterization of the TiH2/C60 cartridge with 5 kJ capacitive driver which demonstrated the capability of producing >30 mg of C60 gas in coaxial plasma gun (~35 cm length) prototype with TiH2/C60 cartridge for a small scale, proof-of-principle experiment on a tokamak. Work supported by the US DOE DE-FG02-08ER85196 grant.

  11. Detection, isolation and characterization of principle synthetic route indicative impurity in telmisartan

    OpenAIRE

    Srinivasan, V.; Sivaramakrishnan, H.; Karthikeyan, B

    2016-01-01

    An unknown impurity was detected in the telmisartan bulk drug (active pharmaceutical ingredient – API) using an isocratic reversed-phase high performance liquid chromatography (HPLC). This impurity was isolated by preparative HPLC. Spectral data of the isolated impurity were collected. Based on the spectral data deriving from two dimensional nuclear magnetic spectroscopy (2D-NMR) and mass spectrometry (MS), the impurity was characterized as “methyl 4′,4′-dibromo methyl biphenyl-2-carboxylate”...

  12. Synthesis and Characterization of Process-Related Impurities of Antihypertensive Drug Olmesartan Medoxomil

    OpenAIRE

    Venkanna, G.; Madhusudhan, G.; K. Mukkanti; A. Sankar; Sampath Kumar, Y.; G. Venakata Narayana

    2013-01-01

    Olmesartan medoxomil (1) is the latest angiotensin receptor antagonist approved by the FDA for the treatment of hypertension. During the process development of olmesartan medoxomil, three process-related impurities were observed along with the final API. These impurities were identified as isopropyl olmesartan (12), dimedoxomil olmesartan (19), dibiphenyl olmesartan (17). The present work describes the synthesis and characterization of all these three impurities.

  13. Geochemical effects of impurities in CO2 on a sandstone reservoir

    NARCIS (Netherlands)

    Koenen, M.; Tambach, T.J.; Neele, F.P.

    2011-01-01

    In most cases, CO2 captured from power plants or large industrial sources contains impurities. As purification of the stream is energy and cost intensive it is necessary to allow a certain level of impurities. The effects of impurities on (short- and long-term) geological storage are, however, uncer

  14. Isolation, synthesis and characterization of impurities in celecoxib, a COX-2 inhibitor.

    Science.gov (United States)

    Satyanarayana, U; Rao, D Sreenivas; Kumar, Y Ravindra; Babu, J Moses; Kumar, P Rajender; Reddy, J Tirupathi

    2004-06-29

    During the impurity profile of Celecoxib, four polar impurities (impurity I, II, III and IV) and one non-polar impurity (impurity V) with respect to Celecoxib were detected by HPLC. LC-MS has been employed in this impurity profile study. The three polar impurities (I, II and III) were found to be process related while impurities (IV and V) turned out to be isomers. The impurities III, IV and V were isolated with the help of preparative HPLC. The structure of impurities III, IV (ortho-isomer) and V (regio-isomer) were confirmed as [5-(4-methylphenyl)-3-trifluoromethyl-1H-pyrazole], 4-[5-(2'-methyl phenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl] benzenesulfonamide, and 4-[4-(4'-methylphenyl)-3-(trifluoromethyl)-1H-pyrazol-1-yl]-benzenesulfonamide, respectively. The structures of impurities I, II, III and IV were confirmed by synthesis and structural characterization using spectral data. However, the impurity V was not synthesized.

  15. Device for sampling and enriching impurities in hydrogen comprising hydrogen-permeable membrane

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Shabbir; Papadias, Dionissios D.; Lee, Sheldon D. H.; Kumar, Romesh

    2017-01-31

    Provided herein are methods and devices to enrich trace quantities of impurities in gaseous mixtures, such as hydrogen fuel. The methods and devices rely on concentration of impurities so as to allow the detection of the impurities using commonly-available detection methods.

  16. Screening of potentially genotoxic impurities in pharmaceuticals by LC-MS and CE-MS

    NARCIS (Netherlands)

    van Wijk, A.M.

    2016-01-01

    Every day we are at risk for exposure to toxic components present in the environment and in food. Also medicines may contain traces of potentially genotoxic impurities (PGI), resulting from residues of process impurities or degradation.The presence of well-defined functional groups in impurities is

  17. Synthesis, Isolation and Characterization of Process-Related Impurities in Salbutamol Sulphate

    Directory of Open Access Journals (Sweden)

    Yogesh Kumar Sharma

    2011-01-01

    Full Text Available Three known and one unknown impurities in salbutamol sulphate bulk drug at level 0.1% (ranging from 0.05-0.1% were detected by gradient reverse phase high performance liquid chromatography. These impurities were preliminarily identified by the mass number of the impurities. Different experiments were conducted and finally synthesized and characterized the known and unknown imputities.

  18. Turbulence measurements in fusion plasmas

    Science.gov (United States)

    Conway, G. D.

    2008-12-01

    Turbulence measurements in magnetically confined toroidal plasmas have a long history and relevance due to the detrimental role of turbulence induced transport on particle, energy, impurity and momentum confinement. The turbulence—the microscopic random fluctuations in particle density, temperature, potential and magnetic field—is generally driven by radial gradients in the plasma density and temperature. The correlation between the turbulence properties and global confinement, via enhanced diffusion, convection and direct conduction, is now well documented. Theory, together with recent measurements, also indicates that non-linear interactions within the turbulence generate large scale zonal flows and geodesic oscillations, which can feed back onto the turbulence and equilibrium profiles creating a complex interdependence. An overview of the current status and understanding of plasma turbulence measurements in the closed flux surface region of magnetic confinement fusion devices is presented, highlighting some recent developments and outstanding problems.

  19. Near-infrared spectroscopy for burning plasma diagnostic applications.

    Science.gov (United States)

    Soukhanovskii, V A

    2008-10-01

    Ultraviolet and visible (UV-VIS, 200-750 nm) atomic spectroscopy of neutral and ionized fuel species (H, D, T, and Li) and impurities (e.g., He, Be, C, and W) is a key element of plasma control and diagnosis on International Thermonuclear Experimental Reactor and future magnetically confined burning plasma experiments (BPXs). Spectroscopic diagnostic implementation and performance issues that arise in the BPX harsh nuclear environment in the UV-VIS range, e.g., degradation of first mirror reflectivity under charge-exchange atom bombardment (erosion) and impurity deposition, permanent and dynamic loss of window, and optical fiber transmission under intense neutron and gamma-ray fluxes, are either absent or not as severe in the near-infrared (NIR, 750-2000 nm) range. An initial survey of NIR diagnostic applications has been undertaken on the National Spherical Torus Experiment. It is demonstrated that NIR spectroscopy can be used for machine protection and plasma control applications, as well as contribute to plasma performance evaluation and physics studies. Emission intensity estimates demonstrate that NIR measurements are possible in the BPX plasma operating parameter range. Complications in the NIR range due to the parasitic background emissions are expected to occur at very high plasma densities, low impurity densities, and at high plasma-facing component temperatures.

  20. Numerical and experimental study of the redistribution of energetic and impurity ions by sawteeth in ASDEX Upgrade

    Science.gov (United States)

    Jaulmes, F.; Geiger, B.; Odstrčil, T.; Weiland, M.; Salewski, M.; Jacobsen, A. S.; Rasmussen, J.; Stejner, M.; Nielsen, S. K.; Westerhof, E.; the EUROfusion MST1 Team; the ASDEX Upgrade Team

    2016-11-01

    In the non-linear phase of a sawtooth, the complete reconnection of field lines around the q  =  1 flux surface often occurs resulting in a radial displacement of the plasma core. A complete time-dependent electromagnetic model of this type of reconnection has been developed and implemented in the EBdyna_go code. This contribution aims at studying the behaviour of ions, both impurity and fast particles, in the pattern of reconnecting field lines during sawtoothing plasma experiments in the ASDEX Upgrade tokamak by using the newly developed numerical framework. Simulations of full reconnection with tungsten impurity that include the centrifugal force are achieved and recover the soft x-ray measurements. Based on this full-reconnection description of the sawtooth, a simple tool dedicated to estimate the duration of the reconnection is introduced. This work then studies the redistribution of fast ions during several experimentally observed sawteeth. In some cases of sawteeth at ASDEX Upgrade, full reconnection is not always observed or expected so the code gives an upper estimate of the actual experimental redistribution. The results of detailed simulations of the crashes are compared with measurements from various diagnostics such as collective Thomson scattering and fast-ion D-alpha (FIDA) spectroscopy, including FIDA tomography. A convincing qualitative agreement is found in different parts of velocity space.

  1. Mass spectrometry of positive ions in capacitively coupled low pressure RF discharges in oxygen with water impurities

    Science.gov (United States)

    Stefanović, Ilija; Stojanović, Vladimir; Boulmer-Leborgne, Chantal; Lecas, Thomas; Kovacevic, Eva; Berndt, Johannes

    2016-07-01

    A capacitively coupled RF oxygen discharge is studied by means of mass spectroscopy. Mass spectra of neutral and positive species are measured in the mid plane between the electrodes at different distances between plasma and mass-spectrometer orifice. In the case of positive ions, as expected, the largest flux originates from \\text{O}2+ . However, a significant number of impurities are detected, especially for low input powers and larger distances. The most abundant positive ions (besides \\text{O}2+ ) are \\text{N}{{\\text{O}}+}, \\text{NO}2+ , {{\\text{H}}+}≤ft({{\\text{H}}2}\\text{O}\\right) , and {{\\text{H}}+}{{≤ft({{\\text{H}}2}\\text{O}\\right)}2} . In particular, for the case of hydrated hydronium ions {{\\text{H}}+}{{≤ft({{\\text{H}}2}\\text{O}\\right)}n} (n  =  1, 2) a surprisingly large flux (for low pressure plasma conditions) is detected. Another interesting fact concerns the {{\\text{H}}2}{{\\text{O}}+} ions. Despite the relatively high ammount of water impurities {{\\text{H}}2}{{\\text{O}}+} ions are present only in traces. The reaction mechanisms leading to the production of the observed ions, especially the hydrated hydronium ions are discussed.

  2. Preparation and properties of HA coating hydrothermally synthesized from plasma sprayed CaHPO4 coating

    Institute of Scientific and Technical Information of China (English)

    FU Tao; HAN Yong; ZHANG Yu-mei; XU Ke-wei

    2001-01-01

    @@ INTRODUCTION Hydroxyapatite (HA) biocoatings can form osseointegration at a shorter time than metallic implants, and plasma sprayed (PS) HA coating has received the widest studies and is now used clinically. However, due to the high temperature of plasma flame, soluble impurity phases and amorphous calcium phosphate were contained which declined the bonding strength of the coating, and spoiled the excellent biological properties of HA.

  3. Collective Thomson scattering system for determination of ion properties in a high flux plasma beam

    NARCIS (Netherlands)

    van der Meiden, H. J.; Vernimmen, J. W. M.; Bystrov, K.; Jesko, K.; Kantor, M. Y.; De Temmerman, G.; Morgan, T. W.

    2016-01-01

    A collective Thomson scattering system has been developed for measuring ion temperature, plasma velocity and impurity concentration in the high density magnetized Magnum-PSI plasma beam, allowing for measurements at low temperature (<5 eV) and high electron density >4 × 1020 m−3, while

  4. Plasma engineering design of a Compact Reversed-Field Pinch Reactor (CRFPR)

    Science.gov (United States)

    Bathke, C. G.; Embrechts, M. J.; Hagenson, R. L.; Krakowski, R. A.; Miller, R. L.

    1983-11-01

    The rationale for and the characteristics of the high-power-density Compact Reversed-Field Pinch Reactor (CRFPR) are discussed. Particular emphasis is given to key plasma engineering aspects of the conceptual design, including plasma operations, current drive, and impurity/ash control by means of pumped limiters or magnetic divertors. A brief description of the Fusion-Power-Core integration is given.

  5. Properties of LuAP: CE scintillator containing intentional impurities

    CERN Document Server

    Petrosyan, A G; Ovanesyan, K; Lecoq, Paul; Auffray, Etiennette; Trummer, Julia; Kronberger, Matthias; Pédrini, C; Dujardin, C; Anfre, P

    2007-01-01

    Single crystals of LuAP:Ce and LuYAP(Lu*70%):Ce co-doped with tetravalent (Hf and Zr) and pentavalent (Ta) ions were grown from melts by the Bridgman process. Underlying absorption, slope of the optical edge and transmission in the range of emission were compared to those of LuAP:Ce crystals. Absorption coefficients at 260 nm less than 2 cm−1 have been recorded in LuAP:Ce crystals containing tetravalent ions that are lower than the corresponding figures (5–6 cm−1) measured in undoped LuAP. At high concentrations of added impurities, despite of suppression of the parasitic underlying absorption below 300 nm, the slope of the optical edge and transmission in the range of emission are seriously damaged. Scintillation parameters of crystals with added impurities are compared to those of LuAP:Ce.

  6. Neutron Scattering on Impurity Nanoclusters in Gel Samples

    Directory of Open Access Journals (Sweden)

    V. B. Efimov

    2015-01-01

    Full Text Available Results of recent SANS experiments with impurity-helium gel (IHG samples in He-II are presented. We estimate the mean size of the impurity nanoparticles that form the frame of the IHG samples and discuss the possibility to use IHG samples for the production of ultracold neutrons (UCNs in He-II cooled to the temperature of a few mK, as well as the reflection of UCNs at any temperature. Our results indicate that the most promising materials for these purposes might be the heavy water gel samples with the mean sizes of D2O clusters of d~8 nm and the heavy alcohol gel samples with the mean sizes of clusters of d~15 nm.

  7. Holographic flows and thermodynamics of Polyakov loop impurities

    CERN Document Server

    Kumar, S Prem

    2016-01-01

    We study holographic probes dual to heavy quark impurities interpolating between fundamental and symmetric/antisymmetric tensor representations in strongly coupled N=4 supersymmetric gauge theory. These correspond to non-conformal D3- and D5-brane probe embeddings in AdS_5 x S^5 exhibiting flows on their world-volumes. By examining the asymptotic regimes of the embeddings and the one-point function of static fields sourced by the boundary impurity, we conclude that the D5-brane embedding describes the screening of fundamental quarks in the UV into an antisymmetric source in the IR, whilst the non-conformal, D3-brane solution interpolates between the symmetric representation in the UV and fundamental sources in the IR. The D5-brane embeddings exhibit nontrivial thermodynamics with multiple branches of solutions, whilst the thermal analogue of the interpolating D3-brane solution does not appear to exist.

  8. Shiba chains of scalar impurities on unconventional superconductors

    Science.gov (United States)

    Neupert, Titus; Yazdani, A.; Bernevig, B. Andrei

    2016-03-01

    We show that a chain of nonmagnetic impurities deposited on a fully gapped two- or three-dimensional superconductor can become a topological one-dimensional superconductor with protected Majorana bound states at its end. A prerequisite is that the pairing potential of the underlying superconductor breaks the spin-rotation symmetry, as it is generically the case in systems with strong spin-orbit coupling. We illustrate this mechanism for a spinless triplet-superconductor (px+i py ) and a time-reversal symmetric Rashba superconductor with a mixture of singlet and triplet pairing. For the latter, we show that the impurity chain can be topologically nontrivial even if the underlying superconductor is topologically trivial.

  9. Gyrokinetic modelling of stationary electron and impurity profiles in tokamaks

    CERN Document Server

    Skyman, Andreas; Tegnered, Daniel

    2014-01-01

    Particle transport due to Ion Temperature Gradient/Trapped Electron (ITG/TE) mode turbulence is investigated using the gyrokinetic code GENE. Both a reduced quasilinear (QL) treatment and nonlinear (NL) simulations are performed for typical tokamak parameters corresponding to ITG dominated turbulence. A selfconsistent treatment is used, where the stationary local profiles are calculated corresponding to zero particle flux simultaneously for electrons and trace impurities. The scaling of the stationary profiles with magnetic shear, safety factor, electron-to-ion temperature ratio, collisionality, toroidal sheared rotation, triangularity, and elongation is investigated. In addition, the effect of different main ion mass on the zero flux condition is discussed. The electron density gradient can significantly affect the stationary impurity profile scaling. It is therefore expected, that a selfconsistent treatment will yield results more comparable to experimental results for parameter scans where the stationary b...

  10. [Influence of impurities on waste plastics pyrolysis: products and emissions].

    Science.gov (United States)

    Zhao, Lei; Wang, Zhong-Hui; Chen, De-Zhen; Ma, Xiao-Bo; Luan, Jian

    2012-01-01

    The study is aimed to evaluate the impact of impurities like food waste, paper, textile and especially soil on the pyrolysis of waste plastics. For this purpose, emissions, gas and liquid products from pyrolysis of waste plastics and impurities were studied, as well as the transfer of element N, Cl, S from the substrates to the pyrolysis products. It was found that the presence of food waste would reduce the heat value of pyrolysis oil to 27 MJ/kg and increase the moisture in the liquid products, therefore the food residue should be removed from waste plastics; and the soil, enhance the waste plastics' pyrolysis by improving the quality of gas and oil products. The presence of food residue, textile and paper leaded to higher gas emissions.

  11. Stability of cocaine impurity profiles during 12 months of storage

    DEFF Research Database (Denmark)

    Nielsen, Louise Stride; Villesen, Palle; Lindholst, Christian

    2016-01-01

    During the lifetime of a cocaine batch from production end to consumption, several alterations may occur, leading to possible changes in the original impurity profile. Such profile changes may eventually result in erroneous forensic evaluations. In the present study, the stability of both...... the alkaloid and the residual solvent impurity profiles of cocaine were evaluated over a period of 12 months under different storage conditions (temperature, purity and weight) using GC-MS and HS-GC-MS, respectively. The sample purity (p ... that the residual solvent profile may be more applicable than the corresponding alkaloid profile when cocaine seizures subjected to different storage conditions are compared. Our results clearly demonstrate that cocaine alkaloid profiles change over time and are most susceptible to sample purity and storage...

  12. Impurities near an antiferromagnetic-singlet quantum critical point

    Science.gov (United States)

    Mendes-Santos, T.; Costa, N. C.; Batrouni, G.; Curro, N.; dos Santos, R. R.; Paiva, T.; Scalettar, R. T.

    2017-02-01

    Heavy-fermion systems and other strongly correlated electron materials often exhibit a competition between antiferromagnetic (AF) and singlet ground states. Using exact quantum Monte Carlo simulations, we examine the effect of impurities in the vicinity of such an AF-singlet quantum critical point (QCP), through an appropriately defined "impurity susceptibility" χimp. Our key finding is a connection within a single calculational framework between AF domains induced on the singlet side of the transition and the behavior of the nuclear magnetic resonance (NMR) relaxation rate 1 /T1 . We show that local NMR measurements provide a diagnostic for the location of the QCP, which agrees remarkably well with the vanishing of the AF order parameter and large values of χimp.

  13. Impurity-induced antiferromagnetic domains in the periodic Anderson model

    Science.gov (United States)

    Benali, A.; Bai, Z. J.; Curro, N. J.; Scalettar, R. T.

    2016-08-01

    A central feature of the periodic Anderson model is the competition between antiferromagnetism, mediated by the Ruderman-Kittel-Kasuya-Yosida interaction at small conduction electron-local electron hybridization V , and singlet formation at large V . At zero temperature, and in dimension d >1 , these two phases are separated by a quantum critical point Vc. We use quantum Monte Carlo (QMC) simulations to explore the effect of impurities which have a local hybridization V*Vc . We measure the suppression of singlet correlations and the antiferromagnetic correlations which form around the impurity, as well as the size of the resulting domain. Exact diagonalization calculations for linear chains allow us to verify that the qualitative features obtained at intermediate coupling and finite T persist to strong coupling and T =0 , regimes which are difficult to access with QMC. Our calculations agree qualitatively with NMR measurements in CeCoIn5 -xCdx .

  14. Multi-level Algorithm for the Anderson Impurity Model

    Science.gov (United States)

    Chandrasekharan, S.; Yoo, J.; Baranger, H. U.

    2004-03-01

    We develop a new quantum Monte Carlo algorithm to solve the Anderson impurity model. Instead of integrating out the Fermions, we work in the Fermion occupation number basis and thus have direct access to the Fermionic physics. The sign problem that arises in this formulation can be solved by a multi-level technique developed by Luscher and Weisz in the context of lattice QCD [JHEP, 0109 (2001) 010]. We use the directed-loop algorithm to update the degrees of freedom. Further, this algorithm allows us to work directly in the Euclidean time continuum limit for arbitrary values of the interaction strength thus avoiding time discretization errors. We present results for the impurity susceptibility and the properties of the screening cloud obtained using the algorithm.

  15. Evaluation of hydrogen and oxygen impurity levels on silicon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kenny, M.J.; Wielunski, L.S.; Netterfield, R.P.; Martin, P.J.; Leistner, A. [Commonwealth Scientific and Industrial Research Organisation (CSIRO), Lindfield, NSW (Australia). Div. of Applied Physics

    1996-12-31

    This paper reports on surface analytical techniques used to quantify surface concentrations of impurities such as oxygen and hydrogen. The following analytical techniques were used: Rutherford and Backscattering, elastic recoil detection, time-of-flight SIMS, spectroscopic ellipsometry, x-ray photoelectron spectroscopy. The results have shown a spread in thickness of oxide layer, ranging from unmeasurable to 1.6 nm. The data must be considered as preliminary at this stage, but give some insight into the suitability of the techniques and a general idea of the significance of impurities at the monolayer level. These measurements have been carried out on a small number of silicon surfaces both semiconductor grade <111> crystalline material and silicon which has been used in sphere fabrication. 5 refs., 1 fig.

  16. Identification and characterization of process-related impurities of trans-resveratrol.

    Science.gov (United States)

    Sivakumar, Balasubramanian; Murugan, Raman; Baskaran, Annamalai; Khadangale, Bhausaheb Pandharinath; Murugan, Saravanan; Senthilkumar, Udayampalayam Palanisamy

    2013-01-01

    This article deals with the identification and characterization of process-related impurities of trans-resveratrol (3,5,4'-trihydroxystilbene), which exhibits several health benefits, including cancer prevention. During the synthesis of the bulk drug resveratrol, three new impurities were observed. The impurities were detected using the high-performance liquid chromatographic (HPLC) method, whose area percentages ranged from 0.05 to 0.3%. A systematic study was carried out to characterize them. These impurities were isolated by preparative HPLC and characterized by spectral data, subjected to co-injection in HPLC, and were found to be matching with the impurities present in the sample. LC-MS was performed to identify the mass of these impurities. Based on their spectral data (IR, NMR, and Mass), these impurities were characterized as 2-benzyl-5-[(E)-2-(4-hydroxyphenyl)ethenyl]benzene-1,3-diol [Impurity-B], 3-(benzyloxy)-5-[(E)-2-(4-hydroxyphenyl)ethenyl]phenol [Impurity-C], 5-{(E)-2-[4-(benzyloxy)phenyl]ethenyl}benzene-1,3-diol [Impurity-D). These compounds are not reported earlier as process-related impurities.

  17. Density of states in a two-dimensional electron gas: Impurity bands and band tails

    Science.gov (United States)

    Gold, A.; Serre, J.; Ghazali, A.

    1988-03-01

    We calculate the density of states of a two-dimensional electron gas in the presence of charged impurities within Klauder's best multiple-scattering approach. The silicon metal-oxide-semiconductor (MOS) system with impurities at the interface is studied in detail. The finite extension of the electron wave function into the bulk is included as well as various dependences of the density of states on the electron, the depletion, and the impurity densities. The transition from an impurity band at low impurity concentration to a band tail at high impurity concentration is found to take place at a certain impurity concentration. If the screening parameter of the electron gas is decreased, the impurity band shifts to lower energy. For low impurity density we find excited impurity bands. Our theory at least qualitatively explains conductivity and infrared-absorption experiments on impurity bands in sodium-doped MOS systems and deep band tails in the gap observed for high doping levels in these systems.

  18. The impact of neutral impurity concentration on charge drift mobility in germanium

    CERN Document Server

    Mei, H; Wang, G -J; Yang, G

    2016-01-01

    We report a new result of the neutral impurity scattering of electrons and holes that has impact on the charge drift mobility in high purity germanium crystals at 77 Kelvin. The charge carrier concentration, mobility and resistivity are measured by Hall Effect system at 77 Kelvin. We investigated the contribution to the total charge drift mobility from ionized impurity scattering, lattice scattering, and neutral impurity scattering with the best theoretical models and experimental data. Several samples with measured Hall mobility from the grown crystals are used for this investigation. With the measured Hall mobility and ionized impurity concentration as well as the theoretical models, we calculated the neutral impurity concentration by the Matthiessen's rule. As a result, the distributions of the neutral impurity concentrations with respect to the radius of the crystals are obtained. Consequently, we demonstrate that neutral impurity scattering is a significant contribution to the charge drift mobility, whic...

  19. Theoretical investigation of formation of impurity bipolaronic states in covalent semiconductors and high temperature superconductors

    CERN Document Server

    Yavidov, B Y

    2001-01-01

    superconducting properties of doped HTSC compounds have been accounted for with framework of lattice and impurity bipolarons concepts. The theoretical results obtained are in satisfactory agreement with experiment. A theory has been developed of carrier localization around an impurity which takes account of correlation effect between carriers, short- and long range interaction in 'carrier-impurity-lattice' system within the framework of the continuum model in the adiabatic approximation. Possibility of impurity (bi)polaron formation in covalent semiconductors (Si) and high temperature superconductors (HTSC) (La sub 2 sub - sub x Sr sub x Cu sub 4) has been studied theoretically. The impurity bi polaron formation has been analyzed by two scenarios: paring and sequential localization of carriers in the vicinity of impurity atom. It is shown that the impurity bi polaron of large radius does not form in Si while its formation is possible in crystals with x<0.186, where x is the ratio of high frequency dielectr...

  20. Coherence Imaging Measurements of Impurity Flow in the Compact Toroidal Hybrid Experiment

    Science.gov (United States)

    Ennis, D. A.; Hartwell, G. J.; Johnson, C. A.; Maurer, D. A.; Allen, S. L.; Meyer, W. H.; Samuell, C. M.

    2016-10-01

    Measurements of impurity ion emissivity and velocity in the Compact Toroidal Hybrid (CTH) experiment are achieved with a new optical coherence imaging diagnostic. The Coherence Imaging Spectroscopy (CIS) technique measures the spectral coherence of an emission line with an imaging interferometer of fixed delay. CIS has a number of advantages when compared to dispersive Doppler spectroscopy, including higher throughput and the capability to provide 2D spectral images, making it ideal for investigating the non-axisymmetric geometry of CTH plasmas. Furthermore, detailed measurements of the ion flow structure provided by CIS combined with predictive computational models could also provide spatially resolved images of complex flow structures, such as those associated with an island divertor. First CIS measurements of CTH plasmas reveal strong signals for C III (465 nm), He II (468 nm) and C II (513 nm) emission. Preliminary analysis of C III interferograms indicate a net toroidal flow on the order of 10 km/s during the time of peak current. Bench tests using Zn and Cd light sources reveal that the temperature of the instrument must be actively controlled to within 0.01°C to limit phase drift of the interferometer resulting in artificially measured flow. Results from this diagnostic will aid in characterizing the ion flow in planned island divertor and MHD mode-locking experiments. Work supported by USDoE Grant DE-FG02-00ER54610.

  1. Type-I integrable quantum impurities in the Heisenberg model

    CERN Document Server

    Doikou, Anastasia

    2013-01-01

    Type-I quantum impurities are investigated in the context of the integrable Heisenberg model. This type of defects is associated to the (q)-harmonic oscillator algebra. The transmission matrices associated to this particular type of defects are computed via the Bethe ansatz methodology for the XXX model, as well as for the critical and non-critical XXZ spin chain. In the attractive regime of the critical XXZ spin chain the transmission amplitudes for the breathers are also identified.

  2. Type-I integrable quantum impurities in the Heisenberg model

    Energy Technology Data Exchange (ETDEWEB)

    Doikou, Anastasia, E-mail: adoikou@upatras.gr

    2013-12-21

    Type-I quantum impurities are investigated in the context of the integrable Heisenberg model. This type of defects is associated to the (q)-harmonic oscillator algebra. The transmission matrices associated to this particular type of defects are computed via the Bethe ansatz methodology for the XXX model, as well as for the critical and non-critical XXZ spin chain. In the attractive regime of the critical XXZ spin chain the transmission amplitudes for the breathers are also identified.

  3. Quantum Impurity in a One-dimensional Trapped Bose Gas

    DEFF Research Database (Denmark)

    Salami Dehkharghani, Amin; Volosniev, A. G.; Zinner, N. T.

    2015-01-01

    We present a new theoretical framework for describing an impurity in a trapped Bose system in one spatial dimension. The theory handles any external confinement, arbitrary mass ratios, and a weak interaction may be included between the Bose particles. To demonstrate our technique, we calculate...... the ground state energy and properties of a sample system with eight bosons and find an excellent agreement with numerically exact results. Our theory can thus provide definite predictions for experiments in cold atomic gases....

  4. Nonlinear Burn Control in Tokamaks using Heating, Non-axisymmetric Magnetic Fields, Isotopic fueling and Impurity injection

    Science.gov (United States)

    Pajares, Andres; Schuster, Eugenio

    2016-10-01

    Plasma density and temperature regulation in future tokamaks such as ITER is arising as one of the main problems in nuclear-fusion control research. The problem, known as burn control, is to regulate the amount of fusion power produced by the burning plasma while avoiding thermal instabilities. Prior work in the area of burn control considered different actuators, such as modulation of the auxiliary power, modulation of the fueling rate, and controlled impurity injection. More recently, the in-vessel coil system was suggested as a feasible actuator since it has the capability of modifying the plasma confinement by generating non-axisymmetric magnetic fields. In this work, a comprehensive, model-based, nonlinear burn control strategy is proposed to integrate all the previously mentioned actuators. A model to take into account the influence of the in-vessel coils on the plasma confinement is proposed based on the plasma collisionality and the density. A simulation study is carried out to show the capability of the controller to drive the system between different operating points while rejecting perturbations. Supported by the US DOE under DE-SC0010661.

  5. Controlling the Gilbert damping using spin pumping and magnetic impurities

    Science.gov (United States)

    Verhagen, Tim; Tinkey, Holly; van Ruitenbeek, Jan; Aarts, Jan

    2013-03-01

    The ability to control the magnetic damping parameter of thin magnetic films is an important issue when designing for example giant magnetoresistance (GMR) devices. A well-known way to influence the damping of the ferromagnetic (F) layer is by using the spin pumping effect in which a spin current is emitted into an adjacent normal (N) layer by bringing the F-layer into ferromagnetic resonance (FMR). As N layer, we used the well studied strongly spin sinking material Pt and the bad spin sink Cu, but also a Cu layer with Co impurities. We find that by adding a small amount of Co impurities, the Cu layer becomes as effective in damping as a Pt layer. In the latter case, the damping is caused by the strong spin orbit coupling. Using magnetic impurities, we rather make use of the inelastic spin scattering. This opens up new ways to control the damping of a ferromagnetic thin layer, for example in current-in-plane (CIP) GMR sensors, where the extra damping can suppress the spin transfer torque which becomes dominant with the further decrease of the size of the sensor.

  6. Gold and Platinum in Silicon - Isolated Impurities Complexes

    CERN Multimedia

    Mcglynn, P

    2002-01-01

    %IS357 :\\\\ \\\\ Gold and platinum impurities in silicon are exploited for the control of minority carrier lifetimes, and this important feature has resulted in sustained research interest over several decades. Although the properties of isolated substitutional Au~atoms are well understood, this is not the case for Pt. Considerable uncertainty exists regarding the nature of several Pt related defects observed in Electron Paramagnetic Resonance~(EPR) and Photo~Luminescence~(PL). One of the objectives of this experiment is to exploit the transformation of radioactive Au isotopes as a means of producing specific Pt centres, and to use our thorough knowledge of Au in silicon to guide in the interpretation of data obtained for the centres when they transform to Pt.\\\\ \\\\ In addition to isolated impurities, the experiment also addresses the question of pairs of atoms formed by Au and Pt. Studies of these impurity pairs have been reported, but the benefits of a direct comparison of the defects in both the Au and Pt form...

  7. Satellite Water Impurity Marker (SWIM) for predicting seasonal cholera outbreaks

    Science.gov (United States)

    Jutla, A. S.; Akanda, A. S.; Islam, S.

    2011-12-01

    Prediction of outbreaks of cholera, a deadly water related disease, remains elusive. Since coastal brackish water provides a natural ecological niche for cholera bacteria and because a powerful evidence of new biotypes is emerging, it is highly unlikely that cholera will be fully eradicated. Therefore, it is necessary to develop cholera prediction model with several months' of lead time. Satellite based estimates of chlorophyll, a surrogate for phytoplankton abundance, has been associated with proliferation of cholera bacteria. However, survival of cholera bacteria in a variety of coastal ecological environment put constraints on predictive abilities of chlorophyll algorithm since it only measures greenness in coastal waters. Here, we propose a new remote sensing reflectance based statistical index: Satellite Water Impurity Marker, or SWIM. This statistical index estimates impurity levels in the coastal waters and is based on the variability observed in the difference between the blue (412nm) and green (555nm) wavelengths in coastal waters. The developed index is bounded between clear and impure water and shows the ability to predict cholera outbreaks in the Bengal Delta with a predicted r2 of 78% with two months lead time. We anticipate that a predictive system based on SWIM will provide essential lead time allowing effective intervention and mitigation strategies to be developed for other cholera endemic regions of the world.

  8. Light scattering from impurity enhanced liquid layers in polycrystalline ice

    Science.gov (United States)

    Thomson, E. S.; Wettlaufer, J. S.; Wilen, L. A.

    2009-12-01

    Impurity enhanced grain boundary premelting underlies a wide range of geophysical phenomena throughout the cryosphere. In particular, it is known that when water droplets freeze in the atmosphere they are highly polycrystalline and impurities are rejected into grain boundaries. The predicted character and sensitivity of grain boundaries to impurities close to the melting point precludes the use of standard techniques for imaging the interface. Unlike their larger more macroscopic relatives such as veins (3 grain intersections) and nodes (4 grain intersections), grain boundaries do not submit to optical microscopy. However, using an experimental light scattering method grain boundary changes can be measured as a function of thermodynamic variables. Accurate analysis of the light scattering data generated using this method requires a full theory of light propagation through the grain boundary layer straddled by ice crystals. Here we present a theory for light scattering from such a boundary, experimental data using NaCl as a dopant, and dicsuss atmospheric implications from the troposphere to the stratosphere.

  9. Nitrogen Impurity Gettering in Oxide Dispersion Ductilized Chromium

    Energy Technology Data Exchange (ETDEWEB)

    Brady, Michael P [ORNL; Anderson, Ian M [ORNL; Weaver, Mark [University of Alabama, Tuscaloosa; Meyer III, Harry M [ORNL; Walker, Larry R [ORNL; Miller, Michael K [ORNL; Larson, David James [ORNL; Wright, Ian G [ORNL; Sikka, Vinod K [ORNL; Rar, Andrei [ORNL; Pharr, George Mathews [ORNL; Keiser, James R [ORNL; Walls, Claudia Alexandra [ORNL

    2003-01-01

    Work by Scruggs in the 1960s demonstrated that tensile ductility could be achieved at room temperature in powder metallurgically-produced Cr alloyed with MgO. During consolidation, much of the MgO converted to the MgCr{sub 2}O{sub 4} spinel phase, which was hypothesized to getter nitrogen from the Cr, rendering it ductile. We have duplicated this effect, achieving room temperature tensile elongations of 4% for hot-pressed Cr-6MgO-(0-1)Ti (wt.%) and 10% for hot-pressed and extruded Cr-6MgO-0.75Ti. Direct incorporation of nitrogen into the MgCr{sub 2}O{sub 4} phase was not detected; however, impurities, particularly nitrogen and sulfur, were observed to segregate to and/or precipitate at interfaces between the MgO/MgCr{sub 2}O{sub 4} phases and the Cr matrix. Exploratory studies of other non-spinel forming oxide dispersions (La{sub 2}O{sub 3}, TiO{sub 2} and Y{sub 2}O{sub 3}) showed a similar pattern of impurity segregation/precipitation, suggesting that there is nothing unique about spinel dispersions in Cr with regards to impurities. However, none of these other dispersions resulted in similar levels of tensile elongation.

  10. NMR investigation of boron impurities in refined metallurgical grade silicon

    Energy Technology Data Exchange (ETDEWEB)

    Grafe, Hans-Joachim; Loeser, Wolfgang; Schmitz, Steffen; Sakaliyska, Miroslava [Leibniz Institute for Solid State and Materials Research (IFW), Dresden (Germany); Wurmehl, Sabine [Leibniz Institute for Solid State and Materials Research (IFW), Dresden (Germany); Institute for Solid State Physics, Technische Universitaet Dresden (Germany); Eisert, Stefan; Reichenbach, Birk; Mueller, Tim [Adensis GmbH, Dresden (Germany); Acker, Joerg; Rietig, Anja; Ducke, Jana [Department of Chemistry, Faculty for Natural Sciences, Brandenburg Technical University Cottbus-Senftenberg, Senftenberg (Germany)

    2015-09-15

    The nuclear magnetic resonance (NMR) method was applied for tracking boron impurities in the refining process of metallurgical grade (MG) silicon. From the NMR signal of the {sup 11}B isotope at an operating temperature 4.2 K, the boron concentration can be estimated down to the order of 1-10 wppm B. After melting and resolidification of MG-Si alloyed with Ca and Ti, a major fraction of B impurities remains in the Si solid solution as inferred from the characteristic NMR frequency. The alloying element Ti does not form substantial fractions of TiB{sub 2}. Acid leaching of crushed powders of MG-Si alloyed with Ca and Ti can diminish the initial impurity content of B suggesting its accumulation in the grain boundary phases. NMR signals of TiB{sub 2} at 4.2 K and room temperature (RT), and of poly-Si with different B doping at 4.2 K. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. NSTX Plasma Response to Lithium Coated Divertor

    Energy Technology Data Exchange (ETDEWEB)

    H.W. Kugel, M.G. Bell, J.P. Allain, R.E. Bell, S. Ding, S.P. Gerhardt, M.A. Jaworski, R. Kaita, J. Kallman, S.M. Kaye, B.P. LeBlanc, R. Maingi, R. Majeski, R. Maqueda, D.K. Mansfield, D. Mueller, R. Nygren, S.F. Paul, R. Raman, A.L. Roquemore, S.A. Sabbagh, H. Schneider, C.H. Skinner, V.A. Soukhanovskii, C.N. Taylor, J.R. Timberlak, W.R. Wampler, L.E. Zakharov, S.J. Zweben, and the NSTX Research Team

    2011-01-21

    NSTX experiments have explored lithium evaporated on a graphite divertor and other plasma facing components in both L- and H- mode confinement regimes heated by high-power neutral beams. Improvements in plasma performance have followed these lithium depositions, including a reduction and eventual elimination of the HeGDC time between discharges, reduced edge neutral density, reduced plasma density, particularly in the edge and the SOL, increased pedestal electron and ion temperature, improved energy confinement and the suppression of ELMs in the H-mode. However, with improvements in confinement and suppression of ELMs, there was a significant secular increase in the effective ion charge Zeff and the radiated power in H-mode plasmas as a result of increases in the carbon and medium-Z metallic impurities. Lithium itself remained at a very low level in the plasma core, <0.1%. Initial results are reported from operation with a Liquid Lithium Divertor (LLD) recently installed.

  12. Pellet-plasma interactions in tokamaks

    DEFF Research Database (Denmark)

    Chang, C.T.

    1991-01-01

    The ablation of a refuelling pellet of solid hydrogen isotopes is governed by the plasma state, especially the density and energy distribution of the electrons. On the other hand, the cryogenic pellet gives rise to perturbations of the plasma temperature and density. Based on extensive experimental...... data, the interaction between the pellet and the plasma is reviewed. Among the subjects discussed are the MHD activity, evolution of temperature and density profiles, and the behaviour of impurities following the injection of a pellet (or pellets). The beneficial effect of density peaking on the energy...... of the plasma. The appearance of striations and the curving of the pellet trajectory are discussed in detail. The possibility is described for using these observations to study the plasma current-density distribution as well as the existence of suprathermal electrons....

  13. Global modelling of plasma-wall interaction in reversed field pinches

    Science.gov (United States)

    Bagatin, M.; Costa, S.; Ortolani, S.

    1989-04-01

    The impurity production and deuterium recycling mechanisms in ETA—BETA II and RFX are firstly discussed by means of a simple model applicable to a stationary plasma interacting with the wall. This gives the time constant and the saturation values of the impurity concentration as a function of the boundary temperature and density. If the latter is sufficiently high, the impurity buildup in the main plasma becomes to some extent stabilized by the shielding effect of the edge. A self-consistent global model of the time evolution of an RFP plasma interacting with the wall is then described. The bulk and edge parameters are derived by solving the energy and particle balance equations incorporating some of the basic plasma-surface processes, such as sputtering, backscattering and desorption. The application of the model to ETA-BETA II confirms the impurity concentrations of the light and metal impurities as well as the time evolution of the average electron density found experimentally under different conditions. The model is then applied to RFX, a larger RFP experiment under construction, whose wall will be protected by a full graphite armour. The time evolution of the discharge shows that carbon sputtering could increase Zeff to ~ 4, but without affecting significantly the plasma performance.

  14. Atomic and molecular processes in JT-60U divertor plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Takenaga, H.; Shimizu, K.; Itami, K. [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment] [and others

    1997-01-01

    Atomic and molecular data are indispensable for the understanding of the divertor characteristics, because behavior of particles in the divertor plasma is closely related to the atomic and molecular processes. In the divertor configuration, heat and particles escaping from the main plasma flow onto the divertor plate along the magnetic field lines. In the divertor region, helium ash must be effectively exhausted, and radiation must be enhanced for the reduction of the heat load onto the divertor plate. In order to exhaust helium ash effectively, the difference between behavior of neutral hydrogen (including deuterium and tritium) and helium in the divertor plasma should be understood. Radiation from the divertor plasma generally caused by the impurities which produced by the erosion of the divertor plate and/or injected by gas-puffing. Therefore, it is important to understand impurity behavior in the divertor plasma. The ions hitting the divertor plate recycle through the processes of neutralization, reflection, absorption and desorption at the divertor plates and molecular dissociation, charge-exchange reaction and ionization in the divertor plasma. Behavior of hydrogen, helium and impurities in the divertor plasmas can not be understood without the atomic and molecular data. In this report, recent results of the divertor study related to the atomic and molecular processes in JT-60U were summarized. Behavior of neural deuterium and helium was discussed in section 2. In section 3, the comparisons between the modelling of the carbon impurity transport and the measurements of C II and C IV were discussed. In section 4, characteristics of the radiative divertor using Ne puffing were reported. The new diagnostic method for the electron density and temperature in the divertor plasmas using the intensity ratios of He I lines was described in section 5. (author)

  15. Nuclear Fusion Research Understanding Plasma-Surface Interactions

    CERN Document Server

    Clark, Robert E.H

    2005-01-01

    It became clear in the early days of fusion research that the effects of the containment vessel (erosion of "impurities") degrade the overall fusion plasma performance. Progress in controlled nuclear fusion research over the last decade has led to magnetically confined plasmas that, in turn, are sufficiently powerful to damage the vessel structures over its lifetime. This book reviews current understanding and concepts to deal with this remaining critical design issue for fusion reactors. It reviews both progress and open questions, largely in terms of available and sought-after plasma-surface interaction data and atomic/molecular data related to these "plasma edge" issues.

  16. Numerical studies on divertor plasmas in helical systems

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, Noriaki (Mitsubishi Atomic Power Industries, Inc., Tokyo (Japan)); Itoh, Kimitaka; Itoh, Sanae

    1989-12-01

    Scrape-off layer and divertor plasmas in helical systems are studied by using the two-dimensional (2D) numerical simulation code. Unified edge divertor analysis code (UEDA code) is applied to the straight helical model of torsatron/helical heliotron configurations. 2D profiles of plasma parameter, neutrals and impurities are obtained. Erosion rate and neutral back flow rate to the core plasma are also evaluated. Various shapes of the buffle plate are examined from the view point of the establishment of 'dense-cold divertor plasma' by which we can avoid the damage of the target plate. (author).

  17. Full density-matrix numerical renormalization group calculation of impurity susceptibility and specific heat of the Anderson impurity model

    Science.gov (United States)

    Merker, L.; Weichselbaum, A.; Costi, T. A.

    2012-08-01

    Recent developments in the numerical renormalization group (NRG) allow the construction of the full density matrix (FDM) of quantum impurity models [see A. Weichselbaum and J. von Delft, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.99.076402 99, 076402 (2007)] by using the completeness of the eliminated states introduced by F. B. Anders and A. Schiller [F. B. Anders and A. Schiller, Phys. Rev. Lett.PRLTAO0031-900710.1103/PhysRevLett.95.196801 95, 196801 (2005)]. While these developments prove particularly useful in the calculation of transient response and finite-temperature Green's functions of quantum impurity models, they may also be used to calculate thermodynamic properties. In this paper, we assess the FDM approach to thermodynamic properties by applying it to the Anderson impurity model. We compare the results for the susceptibility and specific heat to both the conventional approach within NRG and to exact Bethe ansatz results. We also point out a subtlety in the calculation of the susceptibility (in a uniform field) within the FDM approach. Finally, we show numerically that for the Anderson model, the susceptibilities in response to a local and a uniform magnetic field coincide in the wide-band limit, in accordance with the Clogston-Anderson compensation theorem.

  18. Plasma turbulence

    Energy Technology Data Exchange (ETDEWEB)

    Horton, W. [Univ. of Texas, Austin, TX (United States). Inst. for Fusion Studies; Hu, G. [Globalstar LP, San Jose, CA (United States)

    1998-07-01

    The origin of plasma turbulence from currents and spatial gradients in plasmas is described and shown to lead to the dominant transport mechanism in many plasma regimes. A wide variety of turbulent transport mechanism exists in plasmas. In this survey the authors summarize some of the universally observed plasma transport rates.

  19. X-ray Ross filter method for impurity transport studies on DIII-D (abstract)

    Science.gov (United States)

    Bogatu, I. N.; Kim, J. S.; Egdell, D. H.; Snider, R. T.; Brooks, N. H.; Wade, M. R.; West, W. P.

    2001-01-01

    The injection of Ar into the region of the DIII-D divertor is a promising technique for energy dissipation (through radiation and collisions) and consequently for reduction of the heat load on the plates. An important problem related to this technique, is the inherent poisoning of the core plasma by migrating Ar. The Ar core contamination seems also to improve the thermal transport in an advanced operating mode of the tokamak. It is therefore of great importance to measure the evolution of the impurity concentration profile within the core plasma. This goal could be achieved by using the Ross filter method in conjunction with the existing x-ray diagnostics on DIII-D. A basic Ross filter system consists of two identical detectors placed behind two different x-ray absorbing foils looking at the same plasma volume. The foils are made of different elements or compounds with adjacent or nearly adjacent atomic numbers. Their accurate thickness causes the x-ray transmission curves of the two foils to be effectively identical over the entire energy range except within the narrow region between their absorption edges. Since the transmission characteristics of the foils above and below their absorption edges are the same, any difference in the two detected signals is proportional to the total x-ray power of the emission spectrum between these two edge energies. An x-ray Ross filter with its energy pass band centered on the Ar XVII Kα line at 3.14 keV has been designed. This allows for the discrimination of the Ar Kα line only, regardless of Ar ionization state, against any background radiation with energies outside the energy pass band. The Ross filter was installed in front of two of the fan shaped poloidal x-ray arrays on DIII-D. The first measurements showed very good discrimination against Ne, another injected impurity. Emissivity profile evolution of the Kα lines and Ar enhanced continuum within the energy pass band of the Ross filter can be determined from the x

  20. Dynamical Process of Dissociation of Excitons in Polymer Chains with Impurities

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hong-Xia; ZHAO Hui; CHEN Yu-Guang

    2011-01-01

    @@ Within an extended Su-Schrieffer-Heeger model including impurity interactions,the dynamical process of exciton dissociation in the presence of an external electric field is investigated by using a non-adiabatic evolution method Under the action of impurities,the stability as well as the effective mass of the exciton is reduced.Our results show that the field required to dissociate the excitons depends sensitively on the strength of the impurity potential.As the impurity potential strength increases,the dissociation field decreases effectively.The theoretical results are expected to provide useful predictions concerning which polymers with properly impurity-assisted interactions are likely to be more suitable for use in organic solar cells.%Within an extended Su-Schrieffer-Heeger model including impurity interactions, the dynamical process ofexciton dissociation in the presence of an external electric field is investigated by using a non-adiabatic evolution method. Under the action of impurities, the stability as well as the effective mass of the exciton is reduced. Our results show that the field required to dissociate the excitons depends sensitively on the strength of the impurity potential. As the impurity potential strength increases, the dissociation field decreases effectively. The theoretical results are expected to provide useful predictions concerning which polymers with properly impurity-assisted interactions are likely to be more suitable for use in organic solar cells.

  1. Detection and removal of impurities in nitric oxide generated from air by pulsed electrical discharge.

    Science.gov (United States)

    Yu, Binglan; Blaesi, Aron H; Casey, Noel; Raykhtsaum, Grigory; Zazzeron, Luca; Jones, Rosemary; Morrese, Alexander; Dobrynin, Danil; Malhotra, Rajeev; Bloch, Donald B; Goldstein, Lee E; Zapol, Warren M

    2016-11-30

    Inhalation of nitric oxide (NO) produces selective pulmonary vasodilation without dilating the systemic circulation. However, the current NO/N2 cylinder delivery system is cumbersome and expensive. We developed a lightweight, portable, and economical device to generate NO from air by pulsed electrical discharge. The objective of this study was to investigate and optimize the purity and safety of NO generated by this device. By using low temperature streamer discharges in the plasma generator, we produced therapeutic levels of NO with very low levels of nitrogen dioxide (NO2) and ozone. Despite the low temperature, spark generation eroded the surface of the electrodes, contaminating the gas stream with metal particles. During prolonged NO generation there was gradual loss of the iridium high-voltage tip (-90 μg/day) and the platinum-nickel ground electrode (-55 μg/day). Metal particles released from the electrodes were trapped by a high-efficiency particulate air (HEPA) filter. Quadrupole mass spectroscopy measurements of effluent gas during plasma NO generation showed that a single HEPA filter removed all of the metal particles. Mice were exposed to breathing 50 parts per million of electrically generated NO in air for 28 days with only a scavenger and no HEPA filter; the mice did not develop pulmonary inflammation or structural changes and iridium and platinum particles were not detected in the lungs of these mice. In conclusion, an electric plasma generator produced therapeutic levels of NO from air; scavenging and filtration effectively eliminated metallic impurities from the effluent gas. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. A spectroscopic system for time- and space-resolved studies of impurities on the EXTRAP-T2 reversed field pinch

    Science.gov (United States)

    Sallander, J.

    1998-06-01

    The radial distribution of impurity line emission in the EXTRAP-T2 reversed field pinch (RFP) is studied with a five viewing chord, absolutely calibrated, spectrometer system. The light is analyzed with a single 0.5 m grating spectrometer. Different parts of the entrance slit are used for different channels. This arrangement makes it possible to use the system over a wide wavelength range, from 2500 to 6500 Å, without having to recalibrate the relative sensitivity for the different channels. The rather short plasma pulses of 10-15 ms require a high time resolution. The use of photomultiplier tubes provides a time resolution of 10 μs which is limited by the transient recorders used. The result is a robust, low-cost system that produces reliable measurements of the radial dependence of emission from a wide range of impurity ions.

  3. Plasma harmonics

    CERN Document Server

    Ganeev, Rashid A

    2014-01-01

    Preface; Why plasma harmonics? A very brief introduction Early stage of plasma harmonic studies - hopes and frustrations New developments in plasma harmonics studies: first successes Improvements of plasma harmonics; Theoretical basics of plasma harmonics; Basics of HHG Harmonic generation in fullerenes using few-cycle pulsesVarious approaches for description of observed peculiarities of resonant enhancement of a single harmonic in laser plasmaTwo-colour pump resonance-induced enhancement of odd and even harmonics from a tin plasmaCalculations of single harmonic generation from Mn plasma;Low-o

  4. Chemistry characterization and samples beryllium process impurity determination; Caracterizacao quimica e determinacao de impurezas de amostras de processo de berilio

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Leonel Mathry de

    1992-12-01

    Brazil is the greatest world producer of beryl (3 Be O.Al{sub 2}O{sub 3}.6SiO{sub 2}) and has recently begun to produce beryllium compounds by means of a pilot plant constructed at Governador Valadares city (Minas Gerais - Brazil). The aim of this work was the determination of trace level impurities and macro constituents in the tenth % range to support analytical control process of plant production and characterization of beryllium compounds. The impurities separations and purification process was developed by two steps procedure. The first one using EDTA complexation has separated and reduced some impurities to less than 1 {mu}g/ml level. In the second one it was used a chelating resin (Chelex 100) and the separation efficiency was about 75 to 97 % related with the element tested. High pure berylium oxide standard was obtained from purification of Be(OH)2. The R X fluorescence presented only traces of Cu and Si < 1 % Fe and Mn, Zn, Ca, Al, Na and S were completely removed. The beryllium content was determined by direct atomic emission spectroscopy in argon plasma (Dcp) and compared with classic gravimetric method as Be O. The results were in agreement (49,2+/-0,2 % and 48,3+/-0,1 % respectively) between 95 % of confidence. A low temperature gravimetric method for beryllium determination was also studied using Oxine with microwave furnace. A total of 24 elements including macro and trace level were determined by Dcp and/or spectrophotometric methods. The Be/B separation was studied using anionic resin in poly alcohols medium. A more detailed study of equilibrium conditions is necessary. This work was realized at Laboratorio de Analise Mineral (LAM) of Comissao Nacional de Energia Nuclear - Rio de Janeiro (CNEN). (author)

  5. Impurity features in Ni-YSZ-H2-H2O electrodes

    DEFF Research Database (Denmark)

    Utz, A.; Hansen, Karin Vels; Norrman, Kion;

    2011-01-01

    -of-flight secondary ion mass spectrometry). This analysis yields comprehensive information on composition and lateral distribution of impurity species as well as the size of impurity features. Small impurity striations are found at the triple phase boundary (TPB) as well as on the former electrode......–electrolyte interface and the impurity features were found to be influenced by the electrode configuration and the initial behavior of the Ni electrode during thermal exposure (creep or shrinkage).Furthermore, the electrochemical performance (the line specific resistance LSR) was compared to data reported for Ni point...... anodes. Good agreement was obtained for data with comparable impurity features.Additionally, an order of magnitude estimation of the effect of SiO2 content on surface coverage with an impurity film is performed for different electrode designs (point, patterned and cermet anode) and shows different...

  6. Quantum phase transitions in the bosonic single-impurity Anderson model

    Science.gov (United States)

    Lee, H.-J.; Bulla, R.

    2007-04-01

    We consider a quantum impurity model in which a bosonic impurity level is coupled to a non-interacting bosonic bath, with the bosons at the impurity site subject to a local Coulomb repulsion U. Numerical renormalization group calculations for this bosonic single-impurity Anderson model reveal a zero-temperature phase diagram where Mott phases with reduced charge fluctuations are separated from a Bose-Einstein condensed phase by lines of quantum critical points. We discuss possible realizations of this model, such as atomic quantum dots in optical lattices. Furthermore, the bosonic single-impurity Anderson model appears as an effective impurity model in a dynamical mean-field theory of the Bose-Hubbard model.

  7. Impurity doping effects on the orbital thermodynamic properties of hydrogenated graphene, graphane, in Harrison model

    Science.gov (United States)

    Yarmohammadi, Mohsen

    2016-12-01

    Using the Harrison model and Green's function technique, impurity doping effects on the orbital density of states (DOS), electronic heat capacity (EHC) and magnetic susceptibility (MS) of a monolayer hydrogenated graphene, chair-like graphane, are investigated. The effect of scattering between electrons and dilute charged impurities is discussed in terms of the self-consistent Born approximation. Our results show that the graphane is a semiconductor and its band gap decreases with impurity. As a remarkable point, comparatively EHC reaches almost linearly to Schottky anomaly and does not change at low temperatures in the presence of impurity. Generally, EHC and MS increases with impurity doping. Surprisingly, impurity doping only affects the salient behavior of py orbital contribution of carbon atoms due to the symmetry breaking.

  8. Interactions between impurities and breather-pairs in a nonlinear lattice

    Science.gov (United States)

    Lin, Han; Chen, Weizhong; Lu, Lei; Wei, Rongjue

    2003-09-01

    Based on the Frenkel-Kontorova (FK) model with a δ-impurity, this Letter investigates the interactions between impurities and breather-pairs in a nonlinear pendulum chain driven by a vertical vibration. The numerical results show that a long impurity in pendulum length can absorb more energy into the chain and upgrade the energy level of the breather-pair, when the driving frequency is slight lower than that of parametric resonance of the perfect pendulums, while a short one plays a counteractive role. As the chain is driven at a higher frequency, the effect of impurities turns reverse, which shows a clear symmetry and equivalency between long and short impurities. The main results including the effect and the symmetry of impurities generalize the conclusion on the single breather to the breather-pair.

  9. Interactions between impurities and breather-pairs in a nonlinear lattice

    Energy Technology Data Exchange (ETDEWEB)

    Lin Han; Chen Weizhong; Lu Lei; Wei Rongjue

    2003-09-15

    Based on the Frenkel-Kontorova (FK) model with a {delta}-impurity, this Letter investigates the interactions between impurities and breather-pairs in a nonlinear pendulum chain driven by a vertical vibration. The numerical results show that a long impurity in pendulum length can absorb more energy into the chain and upgrade the energy level of the breather-pair, when the driving frequency is slight lower than that of parametric resonance of the perfect pendulums, while a short one plays a counteractive role. As the chain is driven at a higher frequency, the effect of impurities turns reverse, which shows a clear symmetry and equivalency between long and short impurities. The main results including the effect and the symmetry of impurities generalize the conclusion on the single breather to the breather-pair.

  10. A quasi-linear analysis of the impurity effect on turbulent momentum transport and residual stress

    CERN Document Server

    Ko, S H; Singh, R

    2015-01-01

    We study the impact of impurities on turbulence driven intrinsic rotation (via residual stress) in the context of the quasi-linear theory. A two-fluid formulation for main and impurity ions is employed to study ion temperature gradient modes in sheared slab geometry modified by the presence of impurities. An effective form of the parallel Reynolds stress is derived in the center of mass frame of a coupled main ion-impurity system. Analyses show that the contents and the radial profile of impurities have a strong influence on the residual stress. In particular, an impurity profile aligned with that of main ions is shown to cause a considerable reduction of the residual stress, which may lead to the reduction of turbulence driven intrinsic rotation.

  11. Impurity flows and plateau-regime poloidal density variation in a tokamak pedestal

    CERN Document Server

    Landreman, M; Guszejnov, D

    2011-01-01

    In the pedestal of a tokamak, the sharp radial gradients of density and temperature can give rise to poloidal variation in the density of impurities. At the same time, the flow of the impurity species is modified relative to the conventional neoclassical result. In this paper, these changes to the density and flow of a collisional impurity species are calculated for the case when the main ions are in the plateau regime. In this regime it is found that the impurity density can be higher at either the inboard or outboard side. This finding differs from earlier results for banana- or Pfirsch-Schl\\"uter-regime main ions, in which case the impurity density is always higher at the inboard side in the absence of rotation. Finally, the modifications to the impurity flow are also given for the other regimes of main-ion collisionality.

  12. First-principles investigation of the impurity-kink interaction in bcc iron

    Institute of Scientific and Technical Information of China (English)

    YU Tao; CHEN LiQun; WANG ChongYu; QIU ZhengChen; DU JunPing

    2008-01-01

    Using the first-principles self-consistent discrete variational method based on density functional theory, we investigated the effect of light impurities C and N on the electronic structure of kink on the [100](010) edge dislocation (ED) in bcc iron. Our energetic calculations show that the light impurities have a strong segregation tendency to enter the kink. The results of the charge distribution and the local den-sity of states indicate that the strong bonds between the impurity atoms and the neighboring Fe atoms are formed due to the hybridizations of impurity atoms 2p states and Fe 3d4s4p states. The introduction of light impurities can stabilize the kink system, and impedes the sideward motion of the kink in the [100](010) ED. This is, the light impurities induce a strong pinning effect on the [100](010) ED and may result in the solid solute hardening.

  13. Numerical investigation of plasma edge transport and limiter heat fluxes in Wendelstein 7-X startup plasmas with EMC3-EIRENE

    Science.gov (United States)

    Effenberg, F.; Feng, Y.; Schmitz, O.; Frerichs, H.; Bozhenkov, S. A.; Hölbe, H.; König, R.; Krychowiak, M.; Pedersen, T. Sunn; Reiter, D.; Stephey, L.; W7-X Team

    2017-03-01

    The results of a first systematic assessment of plasma edge transport processes for the limiter startup configuration at Wendelstein 7-X are presented. This includes an investigation of transport from intrinsic and externally injected impurities and their impact on the power balance and limiter heat fluxes. The fully 3D coupled plasma fluid and kinetic neutral transport Monte Carlo code EMC3-EIRENE is used. The analysis of the magnetic topology shows that the poloidally and toroidally localized limiters cause a 3D helical scrape-off layer (SOL) consisting of magnetic flux tubes of three different connection lengths L C. The transport in the helical SOL is governed by L C as topological scale length for the parallel plasma loss channel to the limiters. A clear modulation of the plasma pressure with L C is seen. The helical flux tube topology results in counter streaming sonic plasma flows. The heterogeneous SOL plasma structure yields an uneven limiter heat load distribution with localized peaking. Assuming spatially constant anomalous transport coefficients, increasing plasma density yields a reduction of the maximum peak heat loads from 12 MWm-2 to 7.5 MWm-2 and a broadening of the deposited heat fluxes. The impact of impurities on the limiter heat loads is studied by assuming intrinsic carbon impurities eroded from the limiter surfaces with a gross chemical sputtering yield of 2 % . The resulting radiative losses account for less than 10% of the input power in the power balance with marginal impact on the limiter heat loads. It is shown that a significant mitigation of peak heat loads, 40-50%, can be achieved with controlled impurity seeding with nitrogen and neon, which is a method of particular interest for the later island divertor phase.

  14. Analysis of Impurities in Composition B by Thin Layer Chromatography

    Science.gov (United States)

    1978-04-01

    tube with a stirring rod to manimize the entrapment of impurities ir. the solid mass. The mixture was centrifuged for 3 to Z4 minutes to separate the...flask. The washing was repeated twice. To prevent scattering in the spectrophotometric recording. care %as exercised to as- sure that no solid material...corner of the TLC sheet 3.3 cm from each edge. Care was taken to avoid sampling of solid residue into the syringe. The syringe was clamped on a stand

  15. Determination of grain boundary impurity effects in polycrystalline silicon

    Science.gov (United States)

    Kazmerski, L. L.; Dick, J. R.

    1984-06-01

    An analysis is made of the relationships existing between the chemistry and composition of the intergrain regions in polycrystalline silicon, the electrooptical properties of the grain boundaries, and the performance of polycrystalline Si solar cells. The following two impurity mechanisms are emphasized: segregation of oxygen to grain boundaries during heat treatments and the passivation of grain boundaries by incorporation of hydrogen. It is shown that hydrogen is localized at the defects; the effects of hydrogen localization on the electrical characteristics of the grain boundary and of the solar cell are discussed.

  16. Acceptor and donor impurities in GaN nanocrystals

    OpenAIRE

    Echeverría-Arrondo, C.; Pérez-Conde, J.; Bhattacharjee, A. K.

    2010-01-01

    We investigate acceptor and donor states in GaN nanocrystals doped with a single substitutional impurity. Quantum dots (QD's) of zinc-blende structure and spherical shape are considered with the radius ranging from 4.5 to 67.7 A. The size-dependent energy spectra are calculated within the sp3d5s* tight-binding model, which yields a good agreement with the confinement-induced blue shifts observed in undoped QD's. The computed binding energy is strongly enhanced with respect to the experimental...

  17. Wastewater treatment process of organic impurities by Fenton reaction

    Directory of Open Access Journals (Sweden)

    Talgat Mauletuly

    2013-09-01

    Full Text Available The method is for the oxidative degradation of organic contaminants of natural, recycled and waste water. As oxidative degradation of the catalyst, compounds of iron, generated directly in the purification process, wherein the oxidation of the organic impurities by molecular oxygen, activated by a pair H2O2/Fe2 , and hydrogen peroxide taken in an amount of 30 - 40% of that stoichiometrically required. The proposed method has the following advantages: improved performance and efficiency of the water treatment while reducing the cost of its holding.

  18. Probing the local effects of magnetic impurities on superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Yazdani, A.; Jones, B.A.; Lutz, C.P. [Almaden Research Center, San Jose, CA (United States)] [and others

    1997-03-21

    The local effects of isolated magnetic adatoms on the electronic properties of the surface of a superconductor were studied with a low-temperature scanning tunneling microscope. Tunneling spectra obtained near magnetic adsorbates reveal the presence of excitations within the superconductor`s energy gap that can be detected over a few atomic diameters around the impurity at the surface. These excitations are locally asymmetric with respect to tunneling of electrons and holes. A model calculation based on the Bogoliubov-de Gennes equations can be used to understand the details of the local tunneling spectra. 18 refs., 6 figs.

  19. Some transport properties of the two-channel Kondo impurity

    Energy Technology Data Exchange (ETDEWEB)

    Schlottmann, P. [Department of Physics, Florida State University, Tallahassee, Florida 32306 (United States); Zvyagin, A.A. [B. I. Verkin Institute for Low Temperature Physics and Engineering of the Ukrainian Akademy of Sciences, 47 Lenin Ave., 310164, Kharkov (Ukraine)

    1997-04-01

    We consider conduction electrons moving along a ring in two different orbital channels interacting with a spin-1/2 impurity via isotropic spin exchange. The exchange is the same for both channels, but a crystalline field breaks the orbital symmetry. The tower structure of the finite size corrections to the ground state energy is derived from the Bethe ansatz equations and used to discuss the Aharonov{endash}Bohm{endash}Casher interference pattern in the persistent current and the magnetoresistivity. {copyright} {ital 1997 American Institute of Physics.}

  20. CALCULATIONS OF DOUBLE IMPURITY DIFFUSION IN INTEGRATED CIRCUIT PRODUCTION

    Directory of Open Access Journals (Sweden)

    V. A. Bondarev

    2005-01-01

    Full Text Available Analytical formulae for calculating simultaneous diffusion of two impurities in silicon are presented. The formulae are based on analytical solutions of diffusion equations that have been obtained for the first time by the author while using some special mathematical functions. In contrast to usual formal mathematical approaches, new functions are determined in the process of investigation of real physical models. Algorithms involve some important relations from thermodynamics of irreversible processes and also variational thermodynamic functionals that were previously obtained by the author for transfer processes. Calculations considerably reduce the time required for development of new integrated circuits. 

  1. Preparation and Characterization of Impurely Irrigated Soil Adsorbent from Beaches

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    [Objective]We aimed to study the preparation methods of impurely irrigated soil adsorbent from beaches,as well as its ability to absorb phenol.[Method]Using hydrochloric acid as activator,we compared the influences of various soil adsorbents on the adsorption of phenol through the desired orthogonal tests where the usage of saw dust,concentration of hydrochloric acid,liquid-solid ratio and carbonization temperature varied.Afterwards,we characterized this soil adsorbent.[Result]The optimal conditions for pre...

  2. Li-FSI Impurity Impact Study: Final CRADA Report

    Energy Technology Data Exchange (ETDEWEB)

    Pupek, Krzysztof [Argonne National Lab. (ANL), Argonne, IL (United States); Dzwiniel, Trevor [Argonne National Lab. (ANL), Argonne, IL (United States); Krumdick, Gregory [Argonne National Lab. (ANL), Argonne, IL (United States)

    2017-01-01

    There is growing interest in lithium bis(fluorosulfonyl)imide (LiFSI ) as an alternative to LiPF6 and as an additive to electrolytes used in lithium-ion cells. LiFSI has attracted attention because it is reported to have higher ionic conductivity, better high temperature stability, and enhanced stability toward hydrolysis, Also, LiFSI additive to electrolytes can bring benefits of improved storage properties and reduced gas evolution in the cells. Different levels of different electrochemically active impurities could affect the performance of LiFSI as an electrolyte salt for Li-ion batteries, generating inconsistent and conflicting interpretations of the experimental data.

  3. Effect of impurity doping concentration on solar cell output

    Science.gov (United States)

    Iles, P. A.; Soclof, S. I.

    1975-01-01

    Experimental measurements were made of solar cell and related photovoltaic parameters for silicon with high concentrations of dopant impurities. The cell output peaked for doping levels around 10 to the 17th power per cu cm. Independent measurements of diffusion length and open circuit voltage at high doping levels showed severe reductions at concentrations above 10 to the 18th power per cu cm. Theoretical reasons are given to explain these reductions. Indication is given of the problems requiring solution before increased cell output can be achieved at high doping levels.

  4. Resonant States in High-Temperature Superconductors with Impurities

    CERN Document Server

    Kovacevic, Z L; Hayn, R

    2002-01-01

    A microscopic theory of resonant states for the Zn-doped CuO_2 plane in superconducting phase is formulated within the effective t-J model. In the model derived from the original p-d model Zn impurities are considered as vacancies for the d states on Cu sites. In the superconducting phase in addition to the local static perturbation induced by the vacancy a dynamical perturbation appears which results in frequency-dependent perturbation matrix. By employing the T-matrix formalism for the Green functions in terms of the Hubbard operators the local density of electronic states with d-, p- and s-symmetry is calculated.

  5. Overview of SOFC Anode Interactions with Coal Gas Impurities

    Energy Technology Data Exchange (ETDEWEB)

    O. A. Marina; L. R. Pederson; R. Gemmen; K. Gerdes; H. Finklea; I. B. Celik

    2010-03-01

    An overview of the results of SOFC anode interactions with phosphorus, arsenic, selenium, sulfur, antimony, and hydrogen chloride as single contaminants or in combinations is discussed. Tests were performed using both anode- and electrolyte-supported cells in synthetic and actual coal gas for periods greater than 1000 hours. Post-test analyses were performed to identify reaction products formed and their distribution, and compared to phases expected from thermochemical modeling. The ultimate purpose of this work is to establish maximum permissible concentrations for impurities in coal gas, to aid in the selection of appropriate coal gas clean-up technologies.

  6. Impurity distribution and reduction behaviour of quartz in the production of high purity silicon

    OpenAIRE

    Dal Martello, Elena

    2012-01-01

    The production of solar grade silicon is based on the use of expensive high purity carbon and quartz feedstock as well as various silicon refining techniques. Impurities in the feedstock materials enter the silicon during the carbothermic reduction of quartz. The knowledge of the impurity distribution/removal in the feedstock and in the carbothermic reduction process is necessary for targeting less pure and cheaper raw materials.The aim of the present study is to investigate the impurity dist...

  7. Synthesis and Characterization of Process-Related Impurities of Antihypertensive Drug Olmesartan Medoxomil

    Directory of Open Access Journals (Sweden)

    G. Venkanna

    2013-01-01

    Full Text Available Olmesartan medoxomil (1 is the latest angiotensin receptor antagonist approved by the FDA for the treatment of hypertension. During the process development of olmesartan medoxomil, three process-related impurities were observed along with the final API. These impurities were identified as isopropyl olmesartan (12, dimedoxomil olmesartan (19, dibiphenyl olmesartan (17. The present work describes the synthesis and characterization of all these three impurities.

  8. Impurity sublattice localization in ZnO revealed by li marker diffusion

    DEFF Research Database (Denmark)

    Azarov, A.Yu.; Knutsen, K.E.; Neuvonen, P.T.;

    2013-01-01

    Sublattice localization of impurities in compound semiconductors, e.g., ZnO, determines their electronic and optical action. Despite that the impurity position may be envisaged based on charge considerations, the actual localization is often unknown, limiting our understanding of the incorporatio...... interstitials, related to the lattice localization of the impurities. Furthermore, Cd+O and Mg+O co-doping experiments revealed that implanted O atoms act as an efficient blocking “filter” for fast diffusing Zn interstitials....

  9. Refractometry of TGS crystals doped with L-threonine impurity under uniaxial pressure

    Energy Technology Data Exchange (ETDEWEB)

    Stadnyk, V. I., E-mail: vasylstadnyk@ukr.net; Kiryk, Yu. I. [Lviv National University (Ukraine)

    2013-07-15

    The temperature and spectral dependences of the refractive indices of triglycine sulphate (TGS) crystals doped with L-threonine impurity have been investigated. It is established that the introduction of an impurity weakens the temperature dependence of refractive indices. The electronic polarizability, refractions, and parameters of UV oscillators of mechanically deformed impurity crystals are calculated. The temperature coefficients of the phase transition shift are determined.

  10. Cobalt-related impurity centers in diamond: electronic properties and hyperfine parameters

    CERN Document Server

    Larico, R; Machado, W V M; Justo, J F

    2013-01-01

    Cobalt-related impurity centers in diamond have been studied using first principles calculations. We computed the symmetry, formation and transition energies, and hyperfine parameters of cobalt impurities in isolated configurations and in complexes involving vacancies and nitrogen atoms. We found that the Co impurity in a divacant site is energetically favorable and segregates nitrogen atoms in its neighborhood. Our results were discussed in the context of the recently observed Co-related electrically active centers in synthetic diamond.

  11. Simulated Effects of Odd-Alkane Impurities in a Hexane Monolayer on Graphite

    OpenAIRE

    Pint, Cary L.; Roth, Michael W.

    2005-01-01

    We present the results of molecular dynamics simulations of odd alkane impurities present within the hexane (even alkane) monolayer. We simulate various temperatures at ca. 3%, 5%, 10%, and 15% impurities of propane, pentane, heptane, nonane, and undecane, each having a low-temperature solid phase belonging to a different space group as compared to hexane, to study the effects of impurities on the various phases and phase transitions for hexane monolayers that are well-characterized through p...

  12. Intrinsic localized modes and nonlinear impurity modes in curved Fermi-Pasta-Ulam chain

    Indian Academy of Sciences (India)

    Ranja Sarkar; Bishwajyoti Dey

    2008-06-01

    We explore the nature of intrinsic localized modes (ILMs) in a curved FermiPasta-Ulam (FPU) chain and the effects of geometry and second-neighbor interaction on the localization and movability properties of such modes. We determine analytically the structure of the localized modes induced by an isotopic light-mass impurity in this chain. We further demonstrate that a nonlinear impurity mode may be treated as a bound state of an ILM with the impurity.

  13. Synthesis and Characterization of Organic Impurities in Bortezomib Anhydride Produced by a Convergent Technology

    Science.gov (United States)

    Ivanov, Andrey S.; Shishkov, Sergey V.; Zhalnina, Anna A.

    2012-01-01

    A profile of impurities in bortezomib anhydride, produced by a recently developed convergent technology, has been characterized. HPLC-MS analysis of the drug essence revealed three impurities: an epimer of bortezomib, resulting from partial racemization of l-phenylalanine’s stereogenic center during the chemical synthesis, and two epimeric products of oxidative degradation of bortezomib, in which boron is replaced by the OH group. The impurities were obtained by chemical synthesis and characterized by physical methods. PMID:22396904

  14. Density of states of s+d-wave superconductor with Anderson impurities

    Energy Technology Data Exchange (ETDEWEB)

    Borkowski, L S, E-mail: lsb@man.poznan.p [Quantum Physics Division, Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznan (Poland)

    2009-03-01

    We present results for the density of states of a s+d-wave superconductor containing finite concentration of Anderson impurities within the self-consistent slave boson approximation. There may be zero, one or two peaks in the energy gap at low energies. The height of the peaks is controlled by the impurity concentration whereas their position depends on the strength of interaction between impurities and the conduction band. Experimental consequences are briefly discussed.

  15. Optical spectroscopy and current detection during warm-up and destruction of impurity-helium condensates

    Science.gov (United States)

    Krushinskaya, I. N.; Boltnev, R. E.; Bykhalo, I. B.; Pelmenev, A. A.; Khmelenko, V. V.; Lee, D. M.

    2015-06-01

    New experimental results on detection of optical spectra and ion currents during destruction of impurity-helium condensates (IHCs) have been obtained. It is shown that emission during IHC sample destruction is accompanied by current pulses, pressure peaks and temperature changes. The molecular bands of excimer molecules XeO* are assigned to molecules stabilized in films of molecular nitrogen covering the heavier cores of impurity clusters which form impurity-helium condensates.

  16. Multiple-Scattering Approach to the Formation of the Impurity Band in Semiconductors

    Science.gov (United States)

    Ghazali, A.; Serre, J.

    1982-03-01

    The electronic structure of doped semiconductors is studied by using the best approximation of Klauder's impurity-scattering theory which yields a wave-vector- and energy-dependent self-energy Σ(k-->,E). An approximation is used for electron correlation effects. It is shown that as the impurity concentration is decreased, the conduction-band tail progressively splits off, giving an impurity band. The link between the formation of the latter and the general theory of bifurcation is outlined.

  17. Impurities in drug substances and drug products: new approaches to quantification and qualification.

    Science.gov (United States)

    Berridge, J C

    1995-12-01

    Regulatory requirements for the identification, qualification and control of impurities in drug substances and their formulated products are now being increasingly explicitly defined, particularly through the International Conference on Harmonisation. The implications of the recent guidelines are reviewed, both from their regulatory impact and the impact upon analytical technology. Impurities also have important safety consequences, and suggestions for possible routes to the qualification of impurities which do not involve the need to undertake additional studies are made.

  18. Lithium-based surfaces controlling fusion plasma behavior at the plasma-material interfacea)

    Science.gov (United States)

    Allain, Jean Paul; Taylor, Chase N.

    2012-05-01

    The plasma-material interface and its impact on the performance of magnetically confined thermonuclear fusion plasmas are considered to be one of the key scientific gaps in the realization of nuclear fusion power. At this interface, high particle and heat flux from the fusion plasma can limit the material's lifetime and reliability and therefore hinder operation of the fusion device. Lithium-based surfaces are now being used in major magnetic confinement fusion devices and have observed profound effects on plasma performance including enhanced confinement, suppression and control of edge localized modes (ELM), lower hydrogen recycling and impurity suppression. The critical spatial scale length of deuterium and helium particle interactions in lithium ranges between 5-100 nm depending on the incident particle energies at the edge and magnetic configuration. Lithium-based surfaces also range from liquid state to solid lithium coatings on a variety of substrates (e.g., graphite, stainless steel, refractory metal W/Mo/etc., or porous metal structures). Temperature-dependent effects from lithium-based surfaces as plasma facing components (PFC) include magnetohydrodynamic (MHD) instability issues related to liquid lithium, surface impurity, and deuterium retention issues, and anomalous physical sputtering increase at temperatures above lithium's melting point. The paper discusses the viability of lithium-based surfaces in future burning-plasma environments such as those found in ITER and DEMO-like fusion reactor devices.

  19. Influence of the impurity-defect and impurity-impurity interactions on the crystalline silicon solar cells conversion efficiency; Influence des interactions impurete-defaut et impurete-impurete sur le rendement de conversion des cellules photovoltaiques au silicium cristallin

    Energy Technology Data Exchange (ETDEWEB)

    Dubois, S

    2007-05-15

    This study aims at understanding the influence of the impurity - defect interaction on the silicon solar cell performances. We studied first the case of single-crystalline silicon. We combined numerical simulations and experimental data providing new knowledge concerning metal impurities in silicon, to quantify the evolution of the conversion efficiency with the impurity concentration. Mainly due to the gettering effects, iron appears to be quite well tolerated. It is not the case for gold, diffusing too slowly. Hydrogenation effects were limited. We transposed then this study toward multi-crystalline silicon. Iron seems rather well tolerated, due to the gettering effects but also due to the efficiency of the hydrogenation. When slow diffusers are present, multi crystalline silicon is sensitive to thermal degradation. n-type silicon could solve this problem, this material being less sensitive to metal impurities. (author)

  20. Evolution of Spin and Charge in a System with Interacting Impurity and Conducting Electrons

    Institute of Scientific and Technical Information of China (English)

    张永梅; 熊诗杰

    2003-01-01

    We investigate the dynamics of spin and charge in an interacting system consisting of impurity and conducting electrons.The time evolution of spin and charge in the impurity is given by solving the time-dependent Schrodinger equations for the many-body states of the interacting system.By switching on the interaction between impurity and conducting electrons,the spin and charge of the impurity begin oscillations with frequencies that reflect the elementary excitations of the interacting system.The dynamics reflects the basic picture of the Kondo effect.

  1. Experiments on the interactions between impurities and solitary waves in lattice model

    Institute of Scientific and Technical Information of China (English)

    ZHU; Yifei(朱逸斐); CHEN; Weizhong; (陈伟中); Lü; Lei; (吕镭)

    2003-01-01

    The interactions between solitary waves and impurities have been studied experimentally in a 1D nonlinear coupled pendulum chain under vertical excitation. The mass and the coupling are unique, except a single pendulum with length impurity in the chain. The experiment reveals: the long impurity repels breather and attracts kink while the short one attracts breather and repels kink under higher frequency driving, and the long impurity attracts breather and repels kink while the short one repels breather and attracts kink under the lower frequency driving. These results prove the current theoretical prediction based on continuum-limit approximation.

  2. Identification, synthesis, isolation and spectral characterization of potential impurities of montelukast sodium.

    Science.gov (United States)

    Saravanan, M; Siva Kumari, K; Pratap Reddy, P; Naidu, M N; Moses Babu, J; Srivastava, Alok Kumar; Lakshmi Kumar, T; Chandra Sekhar, B V V N; Satyanarayana, Bollikonda

    2008-11-04

    During the process development of montelukast sodium, three polar impurities and one non-polar impurity with respect to montelukast sodium were detected by simple reverse phase high-performance liquid chromatography (HPLC). Initially, all the four impurities were identified by the liquid chromatography-mass spectrometry (LC-MS) data and out of four impurities, three have been prepared by the synthetic method and remaining one is isolated by preparative HPLC. Based on the spectral data (IR, (1)H NMR, (13)C NMR and MS), the structure of these impurities 1-4 were characterised as 1-[[[(1R)-1-[3-[(1E)-2-(7-chloro-2-quinolinyl)ethenyl]phenyl-3-[2-(1-hydroxy-1-methylethyl)phenyl]propyl]thio]methyl]cyclopropane acetamide (impurity-1), {1-[1-{3-[2-(7-chloro-quinolin-2-yl)-vinyl]-phenyl}-3-(2-isopropenyl-phenyl)-propylsulfanylmethyl]-cyclopropyl}-acetic acid (impurity-2), 1-[[[(1R)-1-[3-[(1E)-2-(7-chloro-2-quinolinyl)ethyl]phenyl-3-[2-(1-hydroxy-1-methylethyl)phenyl]propyl]thio]methyl]cyclopropaneacetic acid (impurity-3) and 1-[[[(1R)-1-[3-[(1E)-2-(2-quinolinyl)ethenyl]phenyl-3-[2-(1-hydroxy-1-methylethyl)phenyl]propyl]thio]methyl]cyclopropaneacetic acid (impurity-4).

  3. Impurity Deionization Effects on Surface Recombination DC Current-Voltage Characteristics in MOS Transistors

    Energy Technology Data Exchange (ETDEWEB)

    Chen Zuhui [Lee-Kuan-Yew Postdoctoral Fellow, 2007-2010, Nanyang Technological University, Singapore 639798 (Singapore); Jie Binbin; Sah Chihtang, E-mail: bb_jie@msn.com [Department of Physics, Xiamen University, Xiamen 361005 (China)

    2010-12-15

    Impurity deionization on the direct-current current-voltage characteristics from electron-hole recombination (R-DCIV) at SiO{sub 2}/Si interface traps in MOS transistors is analyzed using the steady-state Shockley-Read-Hall recombination kinetics and the Fermi distributions for electrons and holes. Insignificant distortion is observed over 90% of the bell-shaped R-DCIV curves centered at their peaks when impurity deionization is excluded in the theory. This is due to negligible impurity deionization because of the much lower electron and hole concentrations at the interface than the impurity concentration in the 90% range. (invited papers)

  4. Detection, isolation and characterization of principle synthetic route indicative impurity in telmisartan

    Directory of Open Access Journals (Sweden)

    V. Srinivasan

    2016-11-01

    Full Text Available An unknown impurity was detected in the telmisartan bulk drug (active pharmaceutical ingredient – API using an isocratic reversed-phase high performance liquid chromatography (HPLC. This impurity was isolated by preparative HPLC. Spectral data of the isolated impurity were collected. Based on the spectral data deriving from two dimensional nuclear magnetic spectroscopy (2D-NMR and mass spectrometry (MS, the impurity was characterized as “methyl 4′,4′-dibromo methyl biphenyl-2-carboxylate”. The arrived structure was further confirmed by theoretical studies.

  5. Corrosion behavior of pyroclore-rich titanate ceramics for plutonium disposition ; impurity effects.

    Energy Technology Data Exchange (ETDEWEB)

    Bakel, A. J.

    1999-01-13

    The baseline ceramic contains Ti, U, Ca, Hf, Gd, and Ce, and is made up of only four phases, pyrochlore, zirconolite, rutile, and brannerite. The impurities present in the three other ceramics represent impurities expected in the feed, and result in different phase distributions. The results from 3 day, 90 C MCC-1 tests with impurity ceramics were significantly different than the results from tests with the baseline ceramic. Overall, the addition of impurities to these titanate ceramics alters the phase distributions, which in turn, affects the corrosion behavior.

  6. Suppression of Superfluid Density and the Pseudogap State in the Cuprates by Impurities.

    Science.gov (United States)

    Erdenemunkh, Unurbat; Koopman, Brian; Fu, Ling; Chatterjee, Kamalesh; Wise, W D; Gu, G D; Hudson, E W; Boyer, Michael C

    2016-12-16

    We use scanning tunneling microscopy (STM) to study magnetic Fe impurities intentionally doped into the high-temperature superconductor Bi_{2}Sr_{2}CaCu_{2}O_{8+δ}. Our spectroscopic measurements reveal that Fe impurities introduce low-lying resonances in the density of states at Ω_{1}≈4  meV and Ω_{2}≈15  meV, allowing us to determine that, despite having a large magnetic moment, potential scattering of quasiparticles by Fe impurities dominates magnetic scattering. In addition, using high-resolution spatial characterizations of the local density of states near and away from Fe impurities, we detail the spatial extent of impurity-affected regions as well as provide a local view of impurity-induced effects on the superconducting and pseudogap states. Our studies of Fe impurities, when combined with a reinterpretation of earlier STM work in the context of a two-gap scenario, allow us to present a unified view of the atomic-scale effects of elemental impurities on the pseudogap and superconducting states in hole-doped cuprates; this may help resolve a previously assumed dichotomy between the effects of magnetic and nonmagnetic impurities in these materials.

  7. Estimating the Contribution of Impurities to the Uncertainty of Metal Fixed-Point Temperatures

    Science.gov (United States)

    Hill, K. D.

    2014-04-01

    The estimation of the uncertainty component attributable to impurities remains a central and important topic of fixed-point research. Various methods are available for this estimation, depending on the extent of the available information. The sum of individual estimates method has considerable appeal where there is adequate knowledge of the sensitivity coefficients for each of the impurity elements and sufficiently low uncertainty regarding their concentrations. The overall maximum estimate (OME) forsakes the behavior of the individual elements by assuming that the cryoscopic constant adequately represents (or is an upper bound for) the sensitivity coefficients of the individual impurities. Validation of these methods using melting and/or freezing curves is recommended to provide confidence. Recent investigations of indium, tin, and zinc fixed points are reported. Glow discharge mass spectrometry was used to determine the impurity concentrations of the metals used to fill the cells. Melting curves were analyzed to derive an experimental overall impurity concentration (assuming that all impurities have a sensitivity coefficient equivalent to that of the cryoscopic constant). The two values (chemical and experimental) for the overall impurity concentrations were then compared. Based on the data obtained, the pragmatic approach of choosing the larger of the chemical and experimentally derived quantities as the best estimate of the influence of impurities on the temperature of the freezing point is suggested rather than relying solely on the chemical analysis and the OME method to derive the uncertainty component attributable to impurities.

  8. Correlation function and electronic spectral line broadening in relativistic plasmas

    Directory of Open Access Journals (Sweden)

    Douis S.

    2013-01-01

    Full Text Available The electrons dynamics and the time autocorrelation function Cee(t for the total electric microfield of the electrons on positive charge impurity embedded in a plasma are considered when the relativistic dynamic of the electrons is taken into account. We have, at first, built the effective potential governing the electrons dynamics. This potential obeys a nonlinear integral equation that we have solved numerically. Regarding the electron broadening of the line in plasma, we have found that when the plasma parameters change, the amplitude of the collision operator changes in the same way as the time integral of Cee(t. The electron-impurity interaction is taken at first time as screened Deutsh interaction and at the second time as Kelbg interaction. Comparisons of all interesting quantities are made with respect to the previous interactions as well as between classical and relativistic dynamics of electrons.

  9. Cyanex 923 as the extractant in a rare earth element impurity analysis of high-purity cerium oxide.

    Science.gov (United States)

    Duan, Taicheng; Li, Hongfei; Kang, JianZhen; Chen, Hangting

    2004-06-01

    In this work, the feasibility of employing Cyanex 923 as an extractant into the non-cerium REE (rare earth elements) impurity analysis of high-purity cerium oxide was investigated. Through investigations on the choice of the extraction medium, the optimium extraction acidity, matrix Ce4+ effect on the non-cerium REE ion extraction, the optimium extractant concentration and suitable extracting time, and oscillation strengh, it was found that when the phase ratio was at 1:1 and the acicidity was about 2% H2SO4, by gently shaking by hand for about 2 min, 10 mL of 30% Cyanex 923 could not extract even for a 20 ng amount of non-cerium REE3+ ions. However, the extraction efficiency for Ce4+ of 100 mg total amount under the same conditions was about 96%, indicating that a 25-fold preconcentration factor could be achieved. Thus, it was concluded that Cyanex 923 could be used in a REE impurity analysis of 99.9999% or so pure cerium oxide for primary sepapation to elimilate matrix-induced interferences encountered in an ICP-MS (inductively coupled plasma mass spectroscopy) determination.

  10. Effects of Low Energy and High Flux Helium/Hydrogen Plasma Irradiation on Tungsten as Plasma Facing Material

    Institute of Scientific and Technical Information of China (English)

    Ye Minyou

    2005-01-01

    The High-Z material tungsten (W) has been considered as a plasma facing material in the divertor region of ITER (International Thermonuclear Experimental Reactor). In ITER, the divertor is expected to operate under high particle fluxes (> 1023 m-2s-1) from the plasma as well as from intrinsic impurities with a very low energy (< 200 eV). During the past dacade, the effects of plasma irradiation on tungsten have been studied extensively as functions of the ion energy,fluence and surface temperature in the burning plasma conditions. In this paper, recent results concerning blister and bubble formations on the tungsten surface under low energy (< 100 eV) and high flux (> 1021 m-2s-1) He/H plasma irradiation are reviewed to gain a better understanding of the performance of tungsten as a plasma facing material under the burning plasma conditions.

  11. Stability of cocaine impurity profiles during 12 months of storage.

    Science.gov (United States)

    Nielsen, Louise Stride; Villesen, Palle; Lindholst, Christian

    2016-07-01

    During the lifetime of a cocaine batch from production end to consumption, several alterations may occur, leading to possible changes in the original impurity profile. Such profile changes may eventually result in erroneous forensic evaluations. In the present study, the stability of both the alkaloid and the residual solvent impurity profiles of cocaine were evaluated over a period of 12 months under different storage conditions (temperature, purity and weight) using GC-MS and HS-GC-MS, respectively. The sample purity (pprofile. The most significant change was observed in low purity samples stored at 37°C. In contrast, no changes were observed in the residual solvent profile at all storage conditions for the entire 12-month study period. This finding indicates that the residual solvent profile may be more applicable than the corresponding alkaloid profile when cocaine seizures subjected to different storage conditions are compared. Our results clearly demonstrate that cocaine alkaloid profiles change over time and are most susceptible to sample purity and storage temperature. As a consequence, storage conditions and purity should be taken into account when cocaine comparison is conducted in criminal cases.

  12. Impurities effect on the swelling of neutron irradiated beryllium

    Energy Technology Data Exchange (ETDEWEB)

    Donne, M.D.; Scaffidi-Argentina, F. [Institut fuer Neutronenphysik und Reaktortechnik, Karlsruhe (Germany)

    1995-09-01

    An important factor controlling the swelling behaviour of fast neutron irradiated beryllium is the impurity content which can strongly affect both the surface tension and the creep strength of this material. Being the volume swelling of the old beryllium (early sixties) systematically higher than that of the more modem one (end of the seventies), a sensitivity analysis with the aid of the computer code ANFIBE (ANalysis of Fusion Irradiated BEryllium) to investigate the effect of these material properties on the swelling behaviour of neutron irradiated beryllium has been performed. Two sets of experimental data have been selected: the first one named Western refers to quite recently produced Western beryllium, whilst the second one, named Russian refers to relatively old (early sixties) Russian beryllium containing a higher impurity rate than the Western one. The results obtained with the ANFIBE Code were assessed by comparison with experimental data and the used material properties were compared with the data available in the literature. Good agreement between calculated and measured values has been found.

  13. A mechanistic study of impurity segregation at silicon grain boundaries

    Science.gov (United States)

    Käshammer, Peter; Sinno, Talid

    2015-09-01

    The segregation behavior of carbon and oxygen atoms at various silicon grain boundaries was studied using a combination of atomistic simulation and analytical modeling. First, quasi-lattice Grand Canonical Monte Carlo simulations were used to compute segregation isotherms as a function of grain boundary type, impurity atom loading level, and temperature. Next, the atomistic results were employed to regress different analytical segregation models and extract thermodynamic and structural properties. The multilayer Brunauer-Emmett-Teller (BET) isotherm was found to quantitatively capture all the simulation conditions probed in this work, while simpler, single layer models such as the Langmuir-McLean model did not. Some of the BET parameters, namely, the binding free energy of the first adsorption layer and the impurity holding capacity of each layer, were tested for correlation with various measures of grain boundary structure and/or mechanical properties. It was found that certain measures of the atomistic stress distribution correlate strongly with the first-layer binding free energy for substitutional carbon atoms, while common grain boundary identifiers such as sigma value and energy density are not useful in this regard. Preliminary analysis of the more complex case of interstitial oxygen segregation showed that similar measures based on atomistic stress also may be useful here, but more systematic correlative studies are needed to develop a comprehensive picture.

  14. Polarized absorption in determination of impurities in olive oil

    Science.gov (United States)

    Alias, A. N.; Zabidi, Z. M.; Yaacob, Y.; Amir, I. S.; Alshurdin, S. H. N.; Aini, N. A.

    2017-08-01

    The effect of impurities in olive oil blending with palm oil was characterized using polarized absorption method. Polarized absorption was based on the absorption of light which vibrating in a particular plane to pass through the sample. This polarized light allowed the molecule to absorb at the specific orientation. There were four samples have been prepared that were 100:0, 70:30, 50:50 and 0:100 with volume ratio of the olives to palm oil. Two linear polarizers were mounting between the samples in order to get linearly polarized. This specific orientation was affected the absorption spectra of the sample. The results have shown that the analyzing polarizer with angle 00 has bell shape spectra. All the orientation of analyzing polarizer had shown the maximum current output at 100% olive oil. Whereas 100% palm oil has shown the minimum current output. The changing in absorption spectra indicates that the anisotropic properties of each sample were different due to the present of impurities.

  15. When small is big: the role of impurities in electrocatalysis.

    Energy Technology Data Exchange (ETDEWEB)

    Strmcnik, Dusan; Li, Dongguo; Lopes, Pietro P.; Tripkovic, Dusan; Kodama, Kensaku; Stamenkovic, Vojislav R.; Markovic, Nenad M.

    2015-11-01

    Improvements in the fundamental understanding of electrocatalysis have started to revolutionize the development of electrochemical interfaces for the efficient conversion of chemical energy into electricity, as well as for the utilization of electrons to produce new chemicals that then can be re-used in energy conversion systems. Here, some facets of the role of trace level of impurities (from 10-7 to 10-6 M) in electrocatalysis of the oxygen reduction reaction, hydrogen oxidation and evolution reactions, and CO oxidation reactions are explored on well-characterized platinum single crystal surfaces and high surface area materials in alkaline and acidic environments. Of particular interest is the effect of anions (e.g., Cl-, NO3-) and cations (i.e., Cu2+) present in the supporting electrolytes as well as surface defects (i.e., ad-islands) that are present on metal surfaces. The examples presented are chosen to demonstrate that a small level of impurities may play a crucial role in governing the reactivity of electrochemical interfaces.

  16. TEM study of impurity segregations in beryllium pebbles

    Science.gov (United States)

    Klimenkov, M.; Chakin, V.; Moeslang, A.; Rolli, R.

    2014-12-01

    Beryllium is planned to be used as a neutron multiplier in the Helium-cooled Pebble Bed European concept of a breeding blanket of demonstration power reactor DEMO. In order to evaluate the irradiation performance, individual pebbles and constrained pebble beds were neutron-irradiated at temperatures typical of fusion blankets. Beryllium pebbles 1 mm in diameter produced by the rotating electrode method were subjected to a TEM study before and after irradiation at High Flux Reactor, Petten, Netherlands at 861 K. The grain size varied in a wide range from sub-micron size up to several tens of micrometers, which indicated formation bimodal grain size distribution. Based on the application of combined electron energy loss spectroscopy and energy dispersive X-ray spectroscopy methods, we suggest that impurity precipitates play an important role in controlling the mechanical properties of beryllium. The impurity elements were present in beryllium at a sub-percent concentration form beryllide particles of a complex (Fe/Al/Mn/Cr)B composition. These particles are often ordered along dislocations lines, forming several micron-long chains. It can be suggested that fracture surfaces often extended along these chains in irradiated material.

  17. Study of radioactive impurities in neutron transmutation doped germanium

    Energy Technology Data Exchange (ETDEWEB)

    Mathimalar, S.; Dokania, N.; Singh, V. [India-based Neutrino Observatory, Tata Institute of Fundamental Research, Mumbai 400 005 (India); Homi Bhabha National Institute, Anushaktinagar, Mumbai 400 094 (India); Nanal, V., E-mail: nanal@tifr.res.in [Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Mumbai 400 005 (India); Pillay, R.G. [Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Mumbai 400 005 (India); Shrivastava, A. [Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Jagadeesan, K.C.; Thakare, S.V. [Isotope Production and Applications Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

    2015-02-21

    A program to develop low temperature (mK) sensors with neutron transmutation doped Ge for rare event studies with a cryogenic bolometer has been initiated. For this purpose, semiconductor grade Ge wafers are irradiated with thermal neutron flux from Dhruva reactor at Bhabha Atomic Research Centre (BARC), Mumbai. Spectroscopic studies of irradiated samples have revealed that the environment of the capsule used for irradiating the sample leads to significant levels of {sup 65}Zn, {sup 110m}Ag and {sup 182}Ta impurities, which can be reduced by chemical etching of approximately ∼50μm thick surface layer. From measurements of the etched samples in the low background counting setup, activity due to trace impurities of {sup 123}Sb in bulk Ge is estimated to be ∼1Bq/g after irradiation. These estimates indicate that in order to use the NTD Ge sensors for rare event studies, a cooldown period of ∼2 years would be necessary to reduce the radioactive background to ≤1mBq/g.

  18. Interpretation of scanning tunneling quasiparticle interference and impurity states

    Science.gov (United States)

    Kreisel, Andreas; Choubey, P.; Berlijn, T.; Andersen, B. M.; Hirschfeld, P. J.

    2015-03-01

    We use a simple method of calculating inhomogeneous, atomic-scale phenomena in superconductors to obtain real-space conductance maps as measured in scanning tunneling spectroscopy (STM). Our approach makes use of first principles Wannier functions in conjunction with self-consistent solutions of the Bogoliubov-de Gennes equations on a lattice to image superconducting phenomena. This method is a powerful tool since it captures correctly local symmetries on the surface that can be lower than the global lattice symmetry; it improves the spatial resolution from one pixel per lattice point to the sub-atomic scale; and simplifies the interpretation of STM data. As an example, we show how the pattern observed around a Zn impurity in BSCCO-2212, can be understood by accounting for the tails of the Cu Wannier functions, and thus compare perfectly to experimental findings. Further applications of this method include the investigation of impurity states in multiorbital systems as well as the study of quasi particle interference phenomena to enable a better understanding of novel phenomena in high temperature superconductors. P.C., A.K., and P.J.H. were supported by DOE DE-FG02-05ER46236, T.B. as a Wigner Fellow at the Oak Ridge National Laboratory, and B.M.A. and A.K. by Lundbeckfond fellowship (Grant A9318).

  19. Impurity profiling of atropine sulfate by microemulsion electrokinetic chromatography.

    Science.gov (United States)

    Bitar, Yaser; Holzgrabe, Ulrike

    2007-07-27

    An oil-in-water microemulsion electrokinetic chromatography (MEEKC) method has been developed and validated for the determination of atropine, its major degradation products (tropic acid, apoatropine and atropic acid) and related substances from plants material (noratropine, 6-hydroxyhyoscyamine, 7-hydroxyhyoscyamine, hyoscine and littorine). Separation of atropine and all impurities was optimized by varying the voltage, the nature of the oil droplet and the buffer, as well as the organic modifier (methanol, 2-propanol or acetonitrile) and the surfactant type and concentration. The optimum O/W microemulsion background electrolyte (BGE) solution consists of 0.8% (w/w) octane, 6.62% (w/w) 1-butanol, 2.0% (w/w) 2-propanol, 4.44% (w/w) SDS and 86.14% (w/w) 10 mM sodium tetraborate buffer pH 9.2. In order to shorten the analysis time a voltage gradient was applied. The validation was performed with respect to specificity, linearity, range, limit of quantification and detection, precision, accuracy and robustness. The established method allowed the detection and determination of atropine sulfate related substances at impurity levels given in the European Pharmacopoeia. Good agreement was obtained between the established MEEKC method and the traditional RP-HPLC method.

  20. TEM study of impurity segregations in beryllium pebbles

    Energy Technology Data Exchange (ETDEWEB)

    Klimenkov, M., E-mail: michael.klimenkov@kit.edu [Institute for Applied Materials – Applied Materials Physics, Karlsruhe Institute of Technology, Hermann-von-Helmholz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Chakin, V.; Moeslang, A. [Institute for Applied Materials – Applied Materials Physics, Karlsruhe Institute of Technology, Hermann-von-Helmholz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Rolli, R. [Institute for Applied Materials – Materials and Biomechanics, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2014-12-15

    Beryllium is planned to be used as a neutron multiplier in the Helium-cooled Pebble Bed European concept of a breeding blanket of demonstration power reactor DEMO. In order to evaluate the irradiation performance, individual pebbles and constrained pebble beds were neutron-irradiated at temperatures typical of fusion blankets. Beryllium pebbles 1 mm in diameter produced by the rotating electrode method were subjected to a TEM study before and after irradiation at High Flux Reactor, Petten, Netherlands at 861 K. The grain size varied in a wide range from sub-micron size up to several tens of micrometers, which indicated formation bimodal grain size distribution. Based on the application of combined electron energy loss spectroscopy and energy dispersive X-ray spectroscopy methods, we suggest that impurity precipitates play an important role in controlling the mechanical properties of beryllium. The impurity elements were present in beryllium at a sub-percent concentration form beryllide particles of a complex (Fe/Al/Mn/Cr)B composition. These particles are often ordered along dislocations lines, forming several micron-long chains. It can be suggested that fracture surfaces often extended along these chains in irradiated material.

  1. Quantum state transfer in a XX chain with impurities

    Energy Technology Data Exchange (ETDEWEB)

    Zwick, Analia; Osenda, Omar, E-mail: zwick@famaf.unc.edu.ar, E-mail: osenda@famaf.unc.edu.ar [Facultad de Matematica, AstronomIa y Fisica, Universidad Nacional de Cordoba and IFEG-CONICET, Ciudad Universitaria, X5016LAE, Cordoba (Argentina)

    2011-03-11

    One spin excitation states are involved in the transmission of quantum states and entanglement through a quantum spin chain, the localization properties of these states are crucial to achieve the transfer of information from one extreme of the chain to the other. We investigate the bipartite entanglement and localization of the one excitation states in a quantum XX chain with one impurity. The bipartite entanglement is obtained using the concurrence and the localization is analyzed using the inverse participation ratio (IPR). Changing the strength of the exchange coupling of the impurity allows us to control the number of localized or extended states. The analysis of the IPR allows us to identify scenarios where the transmission of quantum states or entanglement can be achieved with a high degree of fidelity. In particular, we identify a regime where the transmission of quantum states between the extremes of the chain is executed in a short transmission time {approx}N/2, where N is the number of spins in the chain, and with a large fidelity.

  2. Influence of impurity gases and operating conditions on PAFC performance

    Energy Technology Data Exchange (ETDEWEB)

    Hirai, K.; Iwasa, N.; Suzuki, M.; Okada, O. [Osaka Gas Co., Ltd. (Japan)] [and others

    1996-12-31

    On-site Phosphoric Acid Fuel Cell (PAFC) Cogeneration system is installed at various test sites, such as at underground parking lot, within chemical plant premises and near urban streets. Since in the current PAFC system, cathode air is supplied to the cell with no particular pretreatment, impurity gases in the air might influence on cell performance. We have investigated the influence of various impurity gases in the cathode gas, on sub-scale single cells, and have found that NO{sub 2}, SO{sub 2} and toluene affect negatively on cell performance. The results of these experiments and the conceivable mechanism of these effects on cell degradation are reported. We have also investigated the influence of other operating parameters, such as temperature, current density, fuel utilization on cell performance. From these experiments, we have found that operating temperature is a significant factor, which mainly determines cell voltage decline rate. The results of sub-scale single cell tests and a short-stack verification test are also reported.

  3. Fusion Plasma Theory project summaries

    Energy Technology Data Exchange (ETDEWEB)

    1993-10-01

    This Project Summary book is a published compilation consisting of short descriptions of each project supported by the Fusion Plasma Theory and Computing Group of the Advanced Physics and Technology Division of the Department of Energy, Office of Fusion Energy. The summaries contained in this volume were written by the individual contractors with minimal editing by the Office of Fusion Energy. Previous summaries were published in February of 1982 and December of 1987. The Plasma Theory program is responsible for the development of concepts and models that describe and predict the behavior of a magnetically confined plasma. Emphasis is given to the modelling and understanding of the processes controlling transport of energy and particles in a toroidal plasma and supporting the design of the International Thermonuclear Experimental Reactor (ITER). A tokamak transport initiative was begun in 1989 to improve understanding of how energy and particles are lost from the plasma by mechanisms that transport them across field lines. The Plasma Theory program has actively-participated in this initiative. Recently, increased attention has been given to issues of importance to the proposed Tokamak Physics Experiment (TPX). Particular attention has been paid to containment and thermalization of fast alpha particles produced in a burning fusion plasma as well as control of sawteeth, current drive, impurity control, and design of improved auxiliary heating. In addition, general models of plasma behavior are developed from physics features common to different confinement geometries. This work uses both analytical and numerical techniques. The Fusion Theory program supports research projects at US government laboratories, universities and industrial contractors. Its support of theoretical work at universities contributes to the office of Fusion Energy mission of training scientific manpower for the US Fusion Energy Program.

  4. Dusty plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Fortov, Vladimir E; Khrapak, Aleksei G; Molotkov, Vladimir I; Petrov, Oleg F [Institute for High Energy Densities, Associated Institute for High Temperatures, Russian Academy of Sciences, Moscow (Russian Federation); Khrapak, Sergei A [Max-Planck-Institut fur Extraterrestrische Physik, Garching (Germany)

    2004-05-31

    The properties of dusty plasmas - low-temperature plasmas containing charged macroparticles - are considered. The most important elementary processes in dusty plasmas and the forces acting on dust particles are investigated. The results of experimental and theoretical investigations of different states of strongly nonideal dusty plasmas - crystal-like, liquid-like, gas-like - are summarized. Waves and oscillations in dusty plasmas, as well as their damping and instability mechanisms, are studied. Some results on dusty plasma investigated under microgravity conditions are presented. New directions of experimental research and potential applications of dusty plasmas are discussed. (reviews of topical problems)

  5. Chapter 8: Plasma operation and control

    Science.gov (United States)

    Gribov, Y.; Humphreys, D.; Kajiwara, K.; Lazarus, E. A.; Lister, J. B.; Ozeki, T.; Portone, A.; Shimada, M.; Sips, A. C. C.; Wesley, J. C.

    2007-06-01

    The ITER plasma control system has the same functional scope as the control systems in present tokamaks. These are plasma operation scenario sequencing, plasma basic control (magnetic and kinetic), plasma advanced control (control of RWMs, NTMs, ELMs, error fields, etc) and plasma fast shutdown. This chapter considers only plasma initiation and plasma basic control. This chapter describes the progress achieved in these areas in the tokamak experiments since the ITER Physics Basis (1999 Nucl. Fusion 39 2577) was written and the results of assessment of ITER to provide the plasma initiation and basic control. This assessment was done for the present ITER design (15 MA machine) at a more detailed level than it was done for the ITER design 1998 (21 MA machine) described in the ITER Physics Basis (1999 Nucl. Fusion 39 2577). The experiments on plasma initiation performed in DIII-D and JT-60U, as well as the theoretical studies performed for ITER, have demonstrated that, within specified assumptions on the plasma confinement and the impurity influx, ITER can produce plasma initiation in a low toroidal electric field (0.3 V m-1), if it is assisted by about 2 MW of ECRF heating. The plasma basic control includes control of the plasma current, position and shape—the plasma magnetic control, as well as control of other plasma global parameters or their profiles—the plasma performance control. The magnetic control is based on more reliable and simpler models of the control objects than those available at present for the plasma kinetic control. Moreover the real time diagnostics used for the magnetic control in many cases are more precise than those used for the kinetic control. Because of these reasons, the plasma magnetic control was developed for modern tokamaks and assessed for ITER better than the kinetic control. However, significant progress has been achieved in the plasma performance control during the last few years. Although the physics basis of plasma operation

  6. Integrated Bayesian Estimation of Zeff in the TEXTOR Tokamak from Bremsstrahlung and CX Impurity Density Measurements

    Science.gov (United States)

    Verdoolaege, G.; Von Hellermann, M. G.; Jaspers, R.; Ichir, M. M.; Van Oost, G.

    2006-11-01

    The validation of diagnostic date from a nuclear fusion experiment is an important issue. The concept of an Integrated Data Analysis (IDA) allows the consistent estimation of plasma parameters from heterogeneous data sets. Here, the determination of the ion effective charge (Zeff) is considered. Several diagnostic methods exist for the determination of Zeff, but the results are in general not in agreement. In this work, the problem of Zeff estimation on the TEXTOR tokamak is approached from the perspective of IDA, in the framework of Bayesian probability theory. The ultimate goal is the estimation of a full Zeff profile that is consistent both with measured bremsstrahlung emissivities, as well as individual impurity spectral line intensities obtained from Charge Exchange Recombination Spectroscopy (CXRS). We present an overview of the various uncertainties that enter the calculation of a Zeff profile from bremsstrahlung date on the one hand, and line intensity data on the other hand. We discuss a simple linear and nonlinear Bayesian model permitting the estimation of a central value for Zeff and the electron density ne on TEXTOR from bremsstrahlung emissivity measurements in the visible, and carbon densities derived from CXRS. Both the central Zeff and ne are sampled using an MCMC algorithm. An outlook is given towards possible model improvements.

  7. Process development and impurities analysis for the bottom antireflective coating material

    Science.gov (United States)

    Ko, Fu-Hsiang; Chen, Hsuen-Li; Huang, Tiao-Yuan; Cheng, Hsu-Chun; Ko, Chu-Jung; Chu, Tieh-Chi

    2001-08-01

    The optical behavior of semiconductor bottom antireflective coating (BARC) material was investigated by both the measurement and simulation methods. The effects of spin- coating rate, interface reflection, BARC layer thickness and photoresist layer thickness were studied. Our results indicated that the 62.5 nm of BARC layer had strong effect on suppressing the light reflection of wavelength of 248 nm form the wafer surface, irrespective of the photoresist layer thickness. Based on the gravimetric method, a high throughput and one-step microwave digestion procedure was developed for the BARC materials. The digestion efficiency increased with the digestion duration and the temperature. By following the established one-step microwave digestion method and inductively coupled plasma mass spectrometry determination, the detection limits obtained for Cr, Ni, Cu, An and Pb were in 0.1 to 1.11 ppb levels. The spike recoveries of the metallic impurities were in the range 86- 102% for the BARC materials. The analytical results of the BARC samples were found to be in reasonably good agreement with our previous method, and the analytical throughput can achieve up to 20 samples per hour for the analysis of 5 elements.

  8. Impurities and Electronic Property Variations of Natural MoS 2 Crystal Surfaces

    KAUST Repository

    Addou, Rafik

    2015-09-22

    Room temperature X-ray photoelectron spectroscopy (XPS), inductively coupled plasma mass spectrometry (ICPMS), high resolution Rutherford backscattering spectrometry (HR-RBS), Kelvin probe method, and scanning tunneling microscopy (STM) are employed to study the properties of a freshly exfoliated surface of geological MoS2 crystals. Our findings reveal that the semiconductor 2H-MoS2 exhibits both n- and p-type behavior, and the work function as measured by the Kelvin probe is found to vary from 4.4 to 5.3 eV. The presence of impurities in parts-per-million (ppm) and a surface defect density of up to 8% of the total area could explain the variation of the Fermi level position. High resolution RBS data also show a large variation in the MoSx composition (1.8 < x < 2.05) at the surface. Thus, the variation in the conductivity, the work function, and stoichiometry across small areas of MoS2 will have to be controlled during crystal growth in order to provide high quality uniform materials for future device fabrication. © 2015 American Chemical Society.

  9. Understanding of Edge Plasmas in Magnetic Fusion Energy Devices

    Energy Technology Data Exchange (ETDEWEB)

    Rognlien, T

    2004-11-01

    A limited overview is given of the theoretical understanding of edge plasmas in fusion devices. This plasma occupies the thin region between the hot core plasma and material walls in magnetically confinement configurations. The region is often formed by a change in magnetic topology from close magnetic field lines (i.e., the core region) and open field lines that contact material surfaces (i.e., the scrape-off layer [SOL]), with the most common example being magnetically diverted tokamaks. The physics of this region is determined by the interaction of plasma with neutral gas in the presence of plasma turbulence, with impurity radiation being an important component. Recent advances in modeling strong, intermittent micro-turbulent edge-plasma transport is given, and the closely coupled self-consistent evolution of the edge-plasma profiles in tokamaks. In addition, selected new results are given for the characterization of edge-plasmas behavior in the areas of edge-pedestal relaxation and SOL transport via Edge-Localize Modes (ELMs), impurity formation including dust, and magnetic field-line stochasticity in tokamaks.

  10. Behavior of the Pb–Li alloy impurities by ICP-MS

    Energy Technology Data Exchange (ETDEWEB)

    Conde, E., E-mail: estefania.conde@ciemat.es [CIEMAT, Av. Complutense 22, 28040 Madrid (Spain); Barrado, A.I.; Pascual, L.; Fernández, M. [CIEMAT, Av. Complutense 22, 28040 Madrid (Spain); Salazar, J.M. Gómez de; Barrena, M.I. [UCM, Dep. Metalurgia, 28040 Madrid (Spain); Quiñones, J. [CIEMAT, Av. Complutense 22, 28040 Madrid (Spain)

    2014-10-15

    Highlights: • In the new test blanket modules (TBM), Pb–Li alloy plays a key role in the new commercial fusion reactors functionality. • It is important to have a complete characterization to define their physicochemical properties and their regenerative function inside the blanket. • Methodology developed is a key tool that allows performing quality control procedures. • It is essential to determine concentrations of major and trace elements presents in Pb–Li alloy. It allows performing quality control procedures. • The inductively coupled plasma mass spectrometry (ICP-MS) is a highly sensitive technique, so enables very low detection limits. - Abstract: The ITER and DEMO projects are developing new test blanket modules (TBM), such as HCLL where the Li–Pb alloy plays a key role in the new commercial fusion reactors functionality. Lithium–lead eutectic alloy has no known uses outside of fusion technology, so the available databases of this material are currently incomplete. It is very important, within the material specifications, to have a complete characterization in order to define their chemical and physical properties, because any variation in the alloy composition has significant consequences in their behavior, and therefore in their regenerative function inside the blanket. This report provides a procedure to perform a wide material characterization, assessing the concentrations of major elements, as well as a review of trace level impurities that can be found both in the eutectic alloy as in starting materials. In this determination inductively coupled plasma mass spectrometry (ICP-MS) technique plays an important role, because as a highly sensitive technique it allows very low detection limits.

  11. Measurements and modeling of transport and impurity radial profiles in the EXTRAP T2R reversed field pinch

    Science.gov (United States)

    Kuldkepp, M.; Brunsell, P. R.; Cecconello, M.; Dux, R.; Menmuir, S.; Rachlew, E.

    2006-09-01

    Radial impurity profiles of oxygen in the rebuilt reversed field pinch EXTRAP T2R [P. R. Brunsell et al., Plasma Phys. Control. Fusion 43, 1457 (2001)] have been measured with a multichannel spectrometer. Absolute ion densities for oxygen peak between 1-4×1010cm-3 for a central electron density of 1×1013cm-3. Transport simulations with the one-dimensional transport code STRAHL with a diffusion coefficient of 20m2 s-1 yield density profiles similar to those measured. Direct measurement of the ion profile evolution during pulsed poloidal current drive suggests that the diffusion coefficient is reduced by a factor ˜2 in the core but remains unaffected toward the edge. Core transport is not significantly affected by the radial magnetic field growth seen at the edge in discharges without feedback control. This indicates that the mode core amplitude remains the same while the mode eigenfunction increases at the edge.

  12. The role of vacancy, impurity, impurity-vacancy complex in the kinetics of LiNH2 complex hydrides:a first-principles study

    Institute of Scientific and Technical Information of China (English)

    Liu Gui-Li; Zhang Guo-Ying; Zhang Hui; Zhu Sheng-Long

    2011-01-01

    This paper studies first-principles plane-wave pseudopotential based on density functional theory of hydrogen vacancy, metal impurity, impurity-vacancy complex in LiNH2, a promising material for hydrogen storage. It finds easy formation of H vacancy in the form of impurity-vacancy complex, and the rate-limiting step to the H diffusion. Based on the analysis of the density of states, it finds that the improvement of the dehydrogenating kinetics of LiNH2 by Ti catalysts and Mg substitution is due to the weak bonding of N-H and the new system metal-like, which makes H atom diffuse easily. The mulliken overlap population analysis shows that H vacancy leads to the H local diffusion, whereas impurity-vacancy complexes result from H nonlocal diffusion, which plays a dominant role in the process of dehydrogenation reaction of LiNH2.

  13. Effects of Large Area Liquid Lithium Limiters on Spherical Torus Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    R. Kaita; R. Majeski; M. Boaz; P. Efthimion; G. Gettelfinger; T. Gray; D. Hoffman; S. Jardin; H. Kugel; P. Marfuta; T. Munsat; C. Neumeyer; S. Raftopoulos; V. Soukhanovskii; J. Spaleta; G. Taylor; J. Timberlake; R. Woolley; L. Zakharov; M. Finkenthal; D. Stutman; L. Delgado-Aparicio; R.P. Seraydarian; G. Antar; R. Doerner; S. Luckhardt; M. Baldwin; R.W. Conn; R. Maingi; M. Menon; R. Causey; D. Buchenauer; M. Ulrickson; B. Jones; D. Rodgers

    2004-06-07

    Use of a large-area liquid lithium surface as a first wall has significantly improved the plasma performance in the Current Drive Experiment-Upgrade (CDX-U) at the Princeton Plasma Physics Laboratory. Previous CDX-U experiments with a partially-covered toroidal lithium limiter tray have shown a decrease in impurities and the recycling of hydrogenic species. Improvements in loading techniques have permitted nearly full coverage of the tray surface with liquid lithium. Under these conditions, there was a large drop in the loop voltage needed to sustain the plasma current. The data are consistent with simulations that indicate more stable plasmas having broader current profiles, higher temperatures, and lowered impurities with liquid lithium walls. As further evidence for reduced recycling with a liquid lithium limiter, the gas puffing had to be increased by up to a factor of eight for the same plasma density achieved with an empty toroidal tray limiter.

  14. Effects of Large Area Liquid Lithium Limiters on Spherical Torus Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Kaita, R; Jajeski, R; Boaz, M; Efthimion, P; Gettelfinger, G; Gray, T; Hoffman, D; Jardin, S; Kugel, H; Marfuta, P; Munsat, T; Neumeyer, C; Raftopoulos, S; Soukhanovskii, V; Spaleta, J; Taylor, G; Timberlake, J; Woolley, R; Zakharov, L; Finkenthal, M; Stutman, D; Delgado-Aparicio, L; Seraydarian, R; Antar, G; Doerner, R; Luckhardt, S; Baldwin, M; Conn, R; Maingi, R; Menon, M; Causey, R; Buchenauer, D; Ulrickson, M; Jones, B; Rodgers, D

    2004-06-03

    Use of a large-area liquid lithium surface as a first wall has significantly improved the plasma performance in the Current Drive Experiment-Upgrade (CDX-U) at the Princeton Plasma Physics Laboratory. Previous CDX-U experiments with a partially-covered toroidal lithium limiter tray have shown a decrease in impurities and the recycling of hydrogenic species. Improvements in loading techniques have permitted nearly full coverage of the tray surface with liquid lithium. Under these conditions, there was a large drop in the loop voltage needed to sustain the plasma current. The data are consistent with simulations that indicate more stable plasmas having broader current profiles, higher temperatures, and lowered impurities with liquid lithium walls. As further evidence for reduced recycling with a liquid lithium limiter, the gas puffing had to be increased by up to a factor of eight for the same plasma density achieved with an empty toroidal tray limiter.

  15. Effects of large area liquid lithium limiters on spherical torus plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Kaita, R. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, NJ 08543 (United States)]. E-mail: kaita@pppl.gov; Majeski, R. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, NJ 08543 (United States); Boaz, M. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, NJ 08543 (United States); Efthimion, P. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, NJ 08543 (United States); Gettelfinger, G. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, NJ 08543 (United States); Gray, T. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, NJ 08543 (United States); Hoffman, D. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, NJ 08543 (United States); Jardin, S. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, NJ 08543 (United States); Kugel, H. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, NJ 08543 (United States); Marfuta, P. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, NJ 08543 (United States); Soukhanovskii, V. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Munsat, T.; Neumeyer, C.; Raftopoulos, S.; Spaleta, J.; Taylor, G.; Timberlake, J.; Woolley, R.; Zakharov, L. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, NJ 08543 (United States); Finkenthal, M.; Stutman, D.; Delgado-Aparicio, L. [Johns Hopkins University, Baltimore, MD (United States); Seraydarian, R.P.; Antar, G.; Doerner, R.; Luckhardt, S.; Baldwin, M.; Conn, R.W. [University of California at San Diego, La Jolla, CA (United States); Maingi, R.; Menon, M. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Causey, R.; Buchenauer, D.; Ulrickson, M.; Jones, B. [Sandia National Laboratories, Albuquerque, NM (United States); Rodgers, D. [Drexel University, Philadelphia, PA (United States)

    2005-03-01

    Use of a large-area liquid lithium surface as a limiter has significantly improved the plasma performance in the Current Drive Experiment-Upgrade (CDX-U) at the Princeton Plasma Physics Laboratory. Previous CDX-U experiments with a partially-covered toroidal lithium limiter tray have shown a decrease in impurities and the recycling of hydrogenic species. Improvements in loading techniques have permitted nearly full coverage of the tray surface with liquid lithium. Under these conditions, there was a large drop in the loop voltage needed to sustain the plasma current. The data are consistent with simulations that indicate more stable plasmas having broader current profiles, higher temperatures, and lowered impurities with liquid lithium walls. As further evidence for reduced recycling with a liquid lithium limiter, the gas puffing had to be increased by up to a factor of eight for the same plasma density achieved with an empty toroidal tray limiter.

  16. Effects of radio frequency fields in the lower hybrid range on temperature gradient driven drift-modes in tokamaks: Momentum and impurity transport

    Science.gov (United States)

    Das, Salil; Jhang, Hogun; Singh, R.; Nordman, H.

    2016-10-01

    The significant effect of impurities in radiation losses and plasma dilution, which result in lower fusion power, and the evaluation of the important effects of intrinsic rotation on transport barrier formation, determination of momentum pinch velocity and its theoretical basis, in tokamak performance is studied using the four-wave parametric process using an electrostatic, collisionless fluid model for ion-temperature-gradient and trapped-electron mode driven turbulence in the presence of radio frequency fields in the lower hybrid (LH) range of frequencies. The beating of the pump and the sidebands exert a ponderomotive force on electrons, modifying the eigenfrequency of the drift waves and influencing the growth rates and the turbulent transport properties. Explicit expressions for the non-linear growth rate and the associated ion thermal conductivity and effective impurity diffusivity are derived. The effects of the rf fields on the momentum and impurity transport coefficients are evaluated for key parameters like rf power, temperature gradients, and magnetic shear. Prince Georges Community College, Largo, Maryland 20774, USA.

  17. Direct Determination of Trace Impurities in High Purity Neodymium after In-Situ Analyte-Matrix Separation by Fluorination Assisted ETV-ICP-AES

    Institute of Scientific and Technical Information of China (English)

    Ruth Wanjau; Hu Bin(胡斌); He Man(何蔓); Jiang Zucheng(江祖成); Wu Yingliang(吴英亮)

    2004-01-01

    Using PTFE as a chemical modifier, a method for the determination of trace impurities in high purity Nd2O3 by in-situ separation and electrothermal vaporization-inductively coupled plasma-atomic emission spectrometry (ETV-ICP-AES) was developed. The analyte-matrix separation and the temperature program of graphite furnace were investigated and optimized. The solid samples were directly introduced into graphite furnace in the form of slurry, where selective volatilization between the matrix and the analytes took place. The Nd matrix was retained in the graphite furnace during the evaporation step, while the trace analyte impurities were vaporized and removed. As a result, the matrix interference that is serious without the modifier is suppressed effectively. The achievable detection limits are (μg·g-1): Ti 0.15, Mn 0.15, Ni 0.20, Co 0.54, respectively. The proposed method was applied to direct determination of trace impurities in high purity Nd2O3 with satisfactory results.

  18. Impurity Dynamics under Neutral Beam Injection at TJ-II (simulation); Dinamica de Impurezas durante la Inyeccion de Haces Neutros en el TJ-II (simulacion)

    Energy Technology Data Exchange (ETDEWEB)

    Guasp, J.; Fuentes, C.; Liniers, M.

    2001-07-01

    In this study the simulations of plasma transport under NBI for TJ-II, previously performed, are extended. Since than a considerable number of important modifications have been introduced in the model: change of magnetic configuration, use of experimental initial profiles, expansion of the Data base from NBI calculations and, mainly, a detailed handling of impurities with inclusion of sputtering effects. Moreover there is now a particular emphasis on the analysis of the conditions for discharge collapse and on the possible effects of single beam injection. This analysis of impurity behaviour with sputtering shows that in the expected usual cases there is no radioactive collapse and that if the recycling coefficients remain lower the unity it is always possible to find a strategy for external gas puffing leading to a stationary state, with densities below the limit and efficient NBI absorption (>50%). The radioactive collapse can appear either at high densities (central value higher than 1.4x10''20 m''3), excessive influx of impurities (i. e. with sputtering rates higher than twice the expected values) o for insufficient injected beam power (less than 45 kW). The present study analyses only the 100{sub 4}4{sub 6}4 configuration of TJ-II, but future works will start a systematic scan of configuration using this same model. (Author) 12 Refs.

  19. Protein binding studies with radiolabeled compounds containing radiochemical impurities. Equilibrium dialysis versus dialysis rate determination

    DEFF Research Database (Denmark)

    Honoré, B

    1987-01-01

    The influence of radiochemical impurities in dialysis experiments with high-affinity ligands is investigated. Albumin binding of labeled decanoate (97% pure) is studied by two dialysis techniques. It is shown that equilibrium dialysis is very sensitive to the presence of impurities resulting...

  20. Impurity profiling of trinitrotoluene using vacuum-outlet gas chromatography-mass spectrometry

    NARCIS (Netherlands)

    Brust, H.; Willemse, S.; Zeng, T.; Asten, A. van; Koeberg, M.; Heijden, A.E.D.M. van der; Bolck, A.; Schoenmakers, P.

    2014-01-01

    In this work, a reliable and robust vacuum-outlet gas chromatography-mass spectrometry (GC-MS) method is introduced for the identification and quantification of impurities in trinitrotoluene (TNT). Vacuum-outlet GC-MS allows for short analysis times the analysis of impurities in TNT was performed in