Note: This page contains sample records for the topic confinement time from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

Confined Quantum Time of Arrivals  

NASA Astrophysics Data System (ADS)

We show that formulating the quantum time of arrival problem in a segment of the real line suggests rephrasing the quantum time of arrival problem to finding states that evolve to unitarily collapse at a given point at a definite time. For the spatially confined particle, we show that the problem admits a solution in the form of an eigenvalue problem of a compact and self-adjoint time of arrival operator derived by a quantization of the classical time of arrival, which is canonically conjugate with the Hamiltonian in a closed subspace of the Hilbert space.

Galapon, Eric A.; Caballar, Roland F.; Ricardo, T., Jr.

2004-10-01

2

Confinement Time Exceeding One Second in a Toroidal Electron Plasma  

NASA Astrophysics Data System (ADS)

Pure electron plasmas (n=2x10^7 cm-3, a=1.27 cm, Rp=17.4 cm) are confined for times exceeding one second in a new toroidal device, the Lawrence Non-neutral Torus II. The plasma is trapped in a 270^o toroidal arc by application of gate potentials to sections of a sectored gold-plated toroidal boundary (b=3.81 cm, R0=18 cm). At base vacuum pressures below 10-8 torr and magnetic field strengths approaching 700 gauss, the m=1 diocotron mode is excited by applying several cycles of rf near the resonant frequency to a section of the wall. The m=1 frequency, which is approximately proportional to the trapped charge, decays on a three second timescale, a confinement time that exceeds by at least an order of magnitude the confinement observed in all other toroidal traps for non-neutral plasmas. Numerical simulations that include toroidal effects are employed to accurately extract plasma charge and m=1 mode amplitude from the experimental data. Future work will include attempts to withdraw the electron source in order to study confinement in a full torus. This work is supported DOE-NSF Grant 0317412.

Stoneking, M. R.; Marler, J. P.; Ha, Bao; Smoniewski, J. C.

2007-11-01

3

Confined quantum time of arrival for the vanishing potential  

SciTech Connect

We give full account of our recent report in E. A. Galapon, R. Caballar, and R. Bahague, Phys. Rev. Lett. 93, 180406 (2004), where it is shown that formulating the free quantum time of arrival problem in a segment of the real line suggests rephrasing the quantum time of arrival problem to finding a complete set of states that evolve to unitarily arrive at a given point at a definite time. For a spatially confined particle, here it is shown explicitly that the problem admits a solution in the form of an eigenvalue problem of a class of compact and self-adjoint time of arrival operators derived by a quantization of the classical time of arrival. The eigenfunctions of these operators are numerically demonstrated to unitarily arrive at the origin at their respective eigenvalues.

Galapon, Eric A. [Theoretical Physics Group, National Institute of Physics, University of the Philippines, Diliman, Quezon City, 1101 (Philippines); Theoretical Physics, University of the Basque Country, Apdo. 644, 48080 Bilbao (Spain); Chemical Physics, University of the Basque Country, Apdo. 644, 48080 Bilbao (Spain); Caballar, Roland F.; Bahague, Ricardo [Theoretical Physics Group, National Institute of Physics, University of the Philippines, Diliman, Quezon City, 1101 (Philippines)

2005-12-15

4

Wave function for time-dependent harmonically confined electrons in a time-dependent electric field.  

PubMed

The many-body wave function of a system of interacting particles confined by a time-dependent harmonic potential and perturbed by a time-dependent spatially homogeneous electric field is derived via the Feynman path-integral method. The wave function is comprised of a phase factor times the solution to the unperturbed time-dependent Schro?dinger equation with the latter being translated by a time-dependent value that satisfies the classical driven equation of motion. The wave function reduces to that of the Harmonic Potential Theorem wave function for the case of the time-independent harmonic confining potential. PMID:24070284

Li, Yu-Qi; Pan, Xiao-Yin; Sahni, Viraht

2013-09-21

5

Confinement time and energy balance in the CTX spheromak  

SciTech Connect

The multipoint Thomson scattering diagnostic on CTX allows measurement of electron plasma pressure. The pressure correlates well with the poloidal flux function. Analysis using equilibrium models allows the (..beta..)/sub vol/ to be calculated from over 100 Thomson scattering profiles taken under standard conditions of spheromak operation where the plasma parameters vary widely within the discharge. The calculated tau/sub E/ increases with central core temperature and with density. The global magnetic energy decay time tau/sub B/2 is consistent with Spitzer-Harm resistivity, but with an anomaly factor of 2 to 4 which may decrease at small ratios of B/n. The n tau/sub E/ product reaches 4 x 10/sup 9/ s cm/sup -3/ during the hottest part of the discharge. A zero-dimensional energy balance code, which accurately includes all the major atomic physics processes and whose parameters have been constrained by comparision to experimental data, is used to identify the causes of energy loss that contribute to the observed confinement time. The most important power loss is that needed to replace the particles being lost and to maintain the constant density of the plateau.

Barnes, C.W.; Henins, I.; Hoida, H.W.; Jarboe, T.R.

1984-01-01

6

Can inertial electrostatic confinement work beyond the ion-ion collisional time scale.  

National Technical Information Service (NTIS)

Inertial electrostatic confinement systems are predicated on a non-equilibrium ion distribution function. Coulomb collisions between ions cause this distribution to relax to a Maxwellian on the ion-ion collisional time-scale. The power required to prevent...

W. M. Nevins

1995-01-01

7

From first-passage times of random walks in confinement to geometry-controlled kinetics  

NASA Astrophysics Data System (ADS)

We present a general theory which allows one to accurately evaluate the mean first-passage time (FPT) for regular random walks in bounded domains, and its extensions to related first-passage observables such as splitting probabilities and occupation times. It is showed that this analytical approach provides a universal scaling dependence of the mean FPT on both the volume of the confining domain and the source-target distance in the case of general scale invariant processes. This analysis is applicable to a broad range of stochastic processes characterized by scale-invariance properties. The full distribution of the FPT can be obtained using similar tools, and displays universal features. This allows to quantify the fluctuations of the FPT in confinement, and to reveal the key role that can be played by the starting position of the random walker. Applications to reaction kinetics in confinement are discussed.

Bénichou, O.; Voituriez, R.

2014-06-01

8

Entanglement and confinement effects constraining polymer chain dynamics on different length and time scales  

NASA Astrophysics Data System (ADS)

With the time constants usually considered to be characteristic for polymer dynamics, namely ? (the segment fluctuation time), ? (the entanglement time), and ? (the longest Rouse relaxation time), the time scales of particular interest: (i) tconfinement, and L is the chain contour length. Based on Langevin-type equations-of-motion coarse-grained predictions for the mean-squared segment displacement and the spin-lattice relaxation dispersion will be outlined for the scenarios "freely-draining", "entangled", and "confined". In the discussion we will juxtapose "local" versus "global" dynamics on the one hand, and "bulk" versus "confined" systems on the other. The experimental technique of particular interest here is field-cycling NMR relaxometry which predominantly probes conformational fluctuations. A comparison with methods sensitive by contrast to translational fluctuations such as field-gradient NMR diffusometry and neutron scattering will be discussed with respect to sensitivity to confinement phenomena, i.e. the so-called corset effect.

Kimmich, Rainer

2010-03-01

9

Fluid and Kinetic Modelling on Timescales Longer than the Confinement Time in Bounded Systems  

SciTech Connect

The problem of fluid modelling on timescales longer than the confinement time is addressed as a problem of decay of high order moments without sources. Several mechanisms for the decay of higher order moments are discussed and very strong experimental evidence is given for toroidal plasmas.

Weiland, Jan [Chalmers University of Technology and EURATOM-VR Association, Gothenburg (Sweden); Zagorodny, Anatoly; Zasenko, Volodymyr [Bogoliubov Institute for Theoretical Physics, Kiev (Ukraine)

2009-10-08

10

A transition state theory for calculating hopping times and diffusion in highly confined fluids  

NASA Astrophysics Data System (ADS)

Monte Carlo simulation is used to study the dynamical crossover from single file diffusion to normal diffusion in fluids confined to narrow channels. We show that the long time diffusion coefficients for a series of systems involving hard and soft interaction potentials can be described in terms of a hopping time that measures the time it takes for a particle to escape the cage formed by its neighbors in the pore. Free energy barriers for the particle hopping process are calculated and used to show that transition state theory effectively describes the hopping time for all the systems studied over a range of pore radii. Our work suggests that the combination of hopping times and transition state theory offers a useful and general framework to describe the dynamics of highly confined, single file fluids.

Wanasundara, Surajith N.; Spiteri, Raymond J.; Bowles, Richard K.

2014-01-01

11

Can inertial electrostatic confinement work beyond the ion-ion collisional time scale?  

SciTech Connect

Inertial electrostatic confinement systems are predicated on a non-equilibrium ion distribution function. Coulomb collisions between ions cause this distribution to relax to a Maxwellian on the ion-ion collisional time-scale. The power required to prevent this relaxation and maintain the IEC configuration for times beyond the ion-ion collisional time scale is shown to be at least an order of magnitude greater than the fusion power produced. It is concluded that IEC systems show little promise as a basis for the development of commercial electric power plants.

Nevins, W.M.

1995-01-01

12

Can inertial electrostatic confinement work beyond the ion--ion collisional time scale?  

SciTech Connect

Inertial electrostatic confinement (IEC) systems are predicated on a nonequilibrium ion distribution function. Coulomb collisions between ions cause this distribution to relax to a Maxwellian on the ion--ion collisional time scale. The power required to prevent this relaxation and maintain the IEC configuration for times beyond the ion--ion collisional time scale is shown to be greater than the fusion power produced. It is concluded that IEC systems show little promise as a basis for the development of commercial electric power plants. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Nevins, W.M. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

1995-10-01

13

Direct observation of low frequency confined acoustic phonons in silver nanoparticles: Terahertz time domain spectroscopy  

NASA Astrophysics Data System (ADS)

Terahertz time domain spectroscopy has been used to study low frequency confined acoustic phonons of silver nanoparticles embedded in poly(vinyl alcohol) matrix in the spectral range of 0.1-2.5 THz. The real and imaginary parts of the dielectric function show two bands at 0.60 and 2.12 THz attributed to the spheroidal and toroidal modes of silver nanoparticles, thus demonstrating the usefulness of terahertz time domain spectroscopy as a complementary technique to Raman spectroscopy in characterizing the nanoparticles.

Kumar, Sunil; Kamaraju, N.; Karthikeyan, B.; Tondusson, M.; Freysz, E.; Sood, A. K.

2010-07-01

14

Energy confinement time and electron density profile shape in TFTR (Tokamak Fusion Test Reactor)  

SciTech Connect

The electron density profiles of intense deuterium neutral-beam- heated plasmas (P{sub tot}/P{sub ohm} {gt} 10) are characterized as a peakedness parameter (F{sub ne} = n{sub eo}/{l angle}n{sub e}{r angle}) in the Tokamak Fusion Test Reactor (TFTR). The gross energy confinement time ({tau}{sub E} = E{sub tot}/P{sub tot}) at the time of maximum stored energy is found to be a weak function of the plasma current and total heating power but depends strongly on the peakedness parameter. A regression study showed {tau}{sub E} = 2.4 {times} 10{sup {minus}3}F{sub ne}{sup 0.76}I{sub P}{sup 0.18}P{sub tot}{sup {minus}0.12} for a data set of 561 discharges in the TFTR. Also {tau}{sub E} can be represented as {tau}{sub E} = {tau}{sub E}{sup L}f(F{sub ne}), where {tau}{sub E}{sup L} is the empirical L-mode scaling result. A similar scaling applies to an appropriately defined incremental energy confinement time ({tau}{sub inc} = dE{sub tot}/dP{sub tot}{vert bar}{sub F{sub ne} = constant}). 14 refs., 4 figs.

Park, H.K.; Bell, M.G.; Goldston, R.J.; Hawryluk, R.J.; Johnson, D.W.; Scott, S.D.; Wieland, R.M.; Zarnstorff, M.C.; Bitter, M.; Bretz, N.; Budny, R.; Dylla, H.F.; Grek, B.; Howell, R.B.; Hsuan , H.; Johnson, L.C.; Mansfield, D.K.; Ramsey, A.T.; Schivell, J.; Taylor, G.; Ulrickson, M.

1989-11-01

15

Vertical X-ray confinement applicable to a time resolved XAFS method  

NASA Astrophysics Data System (ADS)

We present results of focusing X-rays in a configuration suitable for a time-resolved X-ray absorption fine structure (XAFS) measurement in the microsecond range, an improvement by two orders of magnitude over previous techniques at synchrotron sources. The approach employs a new method of focusing X-rays by confinement and combines it with flow techniques from laser technology. The inexpensive focusing method provided a line focus of about 10 ?m with intensity gains of at least 9, which produced quality XAFS spectra of a 58 millimolar solution of zinc sulfate in a fast flowing jet stream.

Livins, P.; Thiel, D. J.; Stern, E. A.; Lewis, A.

1990-05-01

16

Dependence of T cell antigen recognition on T cell receptor-peptide MHC confinement time.  

PubMed

T cell receptor (TCR) binding to diverse peptide-major histocompatibility complex (pMHC) ligands results in various degrees of T cell activation. Here we analyze which binding properties of the TCR-pMHC interaction are responsible for this variation in pMHC activation potency. We have analyzed activation of the 1G4 cytotoxic T lymphocyte clone by cognate pMHC variants and performed thorough correlation analysis of T cell activation with 1G4 TCR-pMHC binding properties measured in solution. We found that both the on rate (k(on)) and off rate (k(off)) contribute to activation potency. Based on our results, we propose a model in which rapid TCR rebinding to the same pMHC after chemical dissociation increases the effective half-life or "confinement time" of a TCR-pMHC interaction. This confinement time model clarifies the role of k(on) in T cell activation and reconciles apparently contradictory reports on the role of TCR-pMHC binding kinetics and affinity in T cell activation. PMID:20137987

Aleksic, Milos; Dushek, Omer; Zhang, Hao; Shenderov, Eugene; Chen, Ji-Li; Cerundolo, Vincenzo; Coombs, Daniel; van der Merwe, P Anton

2010-02-26

17

Real time reciprocal space mapping of nano-islands induced by quantum confinment.  

SciTech Connect

The effects of quantum confinement have been observed pronouncedly in the island morphology of Pb thin films. The evolution of these nano-islands on Si (111)-(7 x 7) and sapphire (001) surfaces has been studied with a new X-ray diffraction method. A charge-coupled device (CCD) camera was used to collect two- and three-dimensional (2-D and 3-D, respectively) maps of the surface X-ray diffraction in real time. Large ranges of the reflectivity curves, with rocking curves at every point on the reflectivity curves, could be measured continuously in a relatively short amount of time. The abundance of information from 2-D k-space maps reveals clear changes in the growth modes of these thin Pb films. With the 3-D extension of this method, it was possible to observe the ordering of the islands. The islands maintain a nearly uniform interisland distance but lack any angular correlation. The interisland ordering is correlated well with the development of 'magic' island heights caused by quantum confinement.

Hong, H.; Gray, A.; Chiang, T. C. (X-Ray Science Division); ( PSC-USR); (Univ. of Illinois)

2011-01-01

18

Waves, Currents, Drifts and Plasma Confinement Time in a Low Temperature, Pulsed, Toroidal, ECR Plasma  

NASA Astrophysics Data System (ADS)

Typically the plasma in purely toroidal field experimental systems is created by a filament source or, in some cases, a helicon plasma source. Here we present measurements of plasma density, electron temperature, flow and confinement time for an electron cyclotron resonance (ECR) created plasma in a purely toroidal field at the Institute of Plasma Research (IPR) in India. A linear array of Langmuir probes was used to measure the density and temperature in a horizontal plane of the torus and a pair or probes is used to measure the vertical electric field arising from charge separation. Mach probes were used to measure bulk plasma flows in the same plane. Through measurements of the decay rate of the plasma density after the 2.45 GHz ECR microwave source turns off, the plasma confinement time as a function of initial toroidal magnetic field strength and fill pressure was investigated. This work was supported by the American Physical Society and the Indo-U.S. Science and Technology Forum (IUSSTF) through the India-U.S. Physics Visitation Program.

Lindon, Michael; Thakur, Arvind; Sharma, P. K.; Satyanarayan, K.; Parmar, P. R.; Virani, Chetan; Scime, Earl; Houshmyandar, Saied

2009-11-01

19

Dependence of energy confinement time on toroidal magnetic field in the TUMAN-3M tokamak  

NASA Astrophysics Data System (ADS)

The influence of toroidal magnetic field on the energy confinement time ?E in the ohmic H-mode has been studied in the TUMAN-3M tokamak with low magnetic field. The experiments were performed at a toroidal magnetic field of B T = 0.68-1.0 T, which is about twice as large as that (0.25-0.5 T) studied in analogous experiments on the NSTX and MAST spherical tokamaks. The results are indicative of a strong dependence of the energy confinement time on toroidal magnetic field: ?E ? B {T/0.75-0.8}. This scaling is much stronger than that projected for the ITER (?E_IPB98 ? B {T/0.15}), while being somewhat weaker than the scalings observed on the NSTX and MAST devices. The stronger (as compared to the ITER scaling) dependence of ?E on B T observed in these experiments should be taken into account in designing thermonuclear facilities with small aspect ratios and toroidal magnetic fields—in particular, fusion neutron sources.

Lebedev, S. V.; Askinazi, L. G.; Vildjunas, M. I.; Zhubr, N. A.; Kornev, V. A.; Krikunov, S. V.; Tukachinsky, A. S.

2012-04-01

20

Fragile-strong fluid crossover and universal relaxation times in a confined hard-disk fluid.  

PubMed

We show that a system of hard disks confined to a narrow channel exhibits a fragile-strong fluid crossover located at the maximum of the isobaric heat capacity and that the relaxation times for different channel widths fall onto a single master curve when rescaled by the relaxation times and temperatures of the crossover. Calculations of the configurational entropy and the inherent structure equation of state find that the crossover is related to properties of the jamming landscape for the model but that the Adam-Gibbs relation does not predict the relaxation behavior. We also show that a facilitated dynamics description of the system, where kinetically excited regions are identified with local packing arrangements of the disks, successfully describes the fragile-strong crossover. PMID:23368134

Yamchi, Mahdi Zaeifi; Ashwin, S S; Bowles, Richard K

2012-11-30

21

Attosecond time delay in the photoionization of endohedral atoms A@C60: A probe of confinement resonances  

NASA Astrophysics Data System (ADS)

The effects of confinement resonances on photoelectron group delay (Wigner time delay) following ionization of an atom encapsulated inside a C60 cage have been studied theoretically using both relativistic and nonrelativistic random phase approximations. The results indicate clearly the resonant character of the confinement oscillations in time delay of the 4d shell of Xe@C60 and present a most direct manifestation of Wigner time delay. These oscillations were missed in a previous theoretical investigation of Ar@C60 [Phys. Rev. Lett. 111, 203003 (2013), 10.1103/PhysRevLett.111.203003].

Deshmukh, P. C.; Mandal, A.; Saha, S.; Kheifets, A. S.; Dolmatov, V. K.; Manson, S. T.

2014-05-01

22

Short-time dynamics of colloidal particles confined between two walls  

NASA Astrophysics Data System (ADS)

The short-time dynamics of colloidal particles in a quasi-two-dimensional geometry is studied by digital video microscopy. The particles (polystyrene spheres) are suspended in water and confined between two parallel glass plates, forming an effective two-dimensional system. The (effective) two-dimensional van Hove function G(r,t) and its self and distinct part are measured with a time resolution of 1/30 s. We found that the general behavior of these time-correlation functions (and their Fourier transforms) is quite similar to that of their three-dimensional counterparts. The effects of the strong hydrodynamic coupling of the particles motion to the walls and that due to the hydrodynamic interactions between particles are contained in the (effective) hydrodynamic function H(k) obtained from the initial slope of F(k,t) [the Fourier transform of G(r,t)]. We found that H(k), as a function of the wave vector k and particle concentration, exhibits a similar qualitative behavior to the hydrodynamic function in homogeneous three-dimensional suspensions of hard spheres. We also found in our systems that the particle fluctuations relax only by self-diffusion for wave vectors where the static structure factor S(k)=1. This result is important for measurements of self-diffusion dynamics in three-dimensional systems by light scattering techniques.

Santana-Solano, Jesús; Arauz-Lara, José Luis

2002-02-01

23

Parametric scaling studies of energy-confinement time for neutral-beam-heated Heliotron-E plasmas.  

National Technical Information Service (NTIS)

Kinetic analysis of the global energy confinement time for neutral-beam-heated Heliotron-E plasmas has been performed with the 1-D, time-independent transport analysis code, PROCTR-Mod. Beam-power scans were performed by firing various number of hydrogen ...

F. Sano Y. Takeiri K. Hanatani

1989-01-01

24

Real-time monitoring of surface-confined platelet activation on TiO2.  

PubMed

For the development of advanced hemocompatible biomaterial functions, there is an unmet demand for in vitro evaluation techniques addressing platelet-surface interactions. We show that the quartz crystal microbalance with dissipation (QCM-D) monitoring technique, here combined with light microscopy, provides a surface sensitive technique that allows for real-time monitoring of the activation and aggregation of the surface-confined platelets on TiO2. The QCM-D signal monitored during adhesion and activation of platelets on TiO2 coated surfaces was found to be different in platelet-poor and platelet-rich environment although light microscopy images taken for each of the two cases looked essentially the same. Interestingly, aggregation of activated platelets was only observed in a protein-rich environment. Our results show that a layer of plasma proteins between the TiO2 surface and the platelets strongly influences the coupling between the platelets and the underlying substrate, explaining both the observed QCM-D signals and the ability of the platelets to aggregate. PMID:24549046

Kunze, Angelika; Hesse, Camilla; Svedhem, Sofia

2014-04-01

25

Acoustic-based measurements of material absorption coefficients: Relationship between laser pulse duration and stress confinement time  

Microsoft Academic Search

Ideally, to use photoacoustics to determine the absorption coefficient ?a of a medium, the laser pulse duration ?p is much shorter than the stress confinement time ?sr required for a laser-induced stress wave to propagate a distance equal to the light penetration depth ?. However, without prior knowledge of ? (equal to 1\\/?a), it is not clear whether a given

Bernard Choi; E. Duco Jansen; Ashley J. Welch

2003-01-01

26

Acoustic-based measurements of material absorption coefficients: Relationship between laser pulse duration and stress confinement time  

Microsoft Academic Search

Ideally, to use photoacoustics to determine the absorption coefficient mua of a medium, the laser pulse duration taup is much shorter than the stress confinement time tausr required for a laser-induced stress wave to propagate a distance equal to the light penetration depth delta. However, without prior knowledge of delta (equal to 1\\/mua), it is not clear whether a given

Bernard Choi; E. Duco Jansen; Ashley J. Welch

2003-01-01

27

Time scale of entropic segregation of flexible polymers in confinement: implications for chromosome segregation in filamentous bacteria.  

PubMed

We report molecular dynamics simulations of the segregation of two overlapping chains in cylindrical confinement. We find that the entropic repulsion between chains can be sufficiently strong to cause segregation on a time scale that is short compared to the one for diffusion. This result implies that entropic driving forces are sufficiently strong to cause rapid bacterial chromosome segregation. PMID:17930265

Arnold, Axel; Jun, Suckjoon

2007-09-01

28

Time scale of entropic segregation of flexible polymers in confinement: Implications for chromosome segregation in filamentous bacteria  

NASA Astrophysics Data System (ADS)

We report molecular dynamics simulations of the segregation of two overlapping chains in cylindrical confinement. We find that the entropic repulsion between chains can be sufficiently strong to cause segregation on a time scale that is short compared to the one for diffusion. This result implies that entropic driving forces are sufficiently strong to cause rapid bacterial chromosome segregation.

Arnold, Axel; Jun, Suckjoon

2007-09-01

29

Dynamic response of materials on subnanosecond time scales, and beryllium properties for inertial confinement fusion  

NASA Astrophysics Data System (ADS)

During the past few years, substantial progress has been made in developing experimental techniques capable of investigating the response of materials to dynamic loading on nanosecond time scales and shorter, with multiple diagnostics probing different aspects of the behavior. These relatively short time scales are scientifically interesting because plastic flow and phase changes in common materials with simple crystal structures-such as iron-may be suppressed, allowing unusual states to be induced and the dynamics of plasticity and polymorphism to be explored. Loading by laser-induced ablation can be particularly convenient: this technique has been used to impart shocks and isentropic compression waves from ~1 to 200 GPa in a range of elements and alloys, with diagnostics including line imaging surface velocimetry, surface displacement (framed area imaging), x-ray diffraction (single crystal and polycrystal), ellipsometry, and Raman spectroscopy. A major motivation has been the study of the properties of beryllium under conditions relevant to the fuel capsule in inertial confinement fusion: magnetically driven shock and isentropic compression shots at Z were used to investigate the equation of state and shock melting characteristics, complemented by laser ablation experiments to investigate plasticity and heterogeneous response from the polycrystalline microstructure. These results will help to constrain acceptable tolerances on manufacturing, and possible loading paths, for inertial fusion ignition experiments at the National Ignition Facility. Laser-based techniques are being developed further for future material dynamics experiments, where it should be possible to obtain high quality data on strength and phase changes up to at least 1 TPa.

Swift, Damian C.; Tierney, Thomas E.; Luo, Sheng-Nian; Paisley, Dennis L.; Kyrala, George A.; Hauer, Allan; Greenfield, Scott R.; Koskelo, Aaron C.; McClellan, Kenneth J.; Lorenzana, Hector E.; Kalantar, Daniel; Remington, Bruce A.; Peralta, Pedro; Loomis, Eric

2005-05-01

30

The laser-induced plasma persistence time extension in low pressures using the ablated mass confinement method  

NASA Astrophysics Data System (ADS)

The laser-induced plasma characteristics are strongly dependent on the surrounding pressure. Confining of the rapidly expanding plasma at low pressure conditions has shown that it is possible to perform the laser-induced breakdown spectroscopy (LIBS) detection by using a long gate width CCD detector. The acrylic window is placed above the sample for adjusting the plasma confining height for optimally extending the plasma persistence time. At 1 mm confining height at 1 torr, the signal intensity of Al III emission (452.8945 nm) was enhanced up to 5.5 times the free expansion case. The signal intensity was markedly lower at 760 torr as thickness of the window became larger, whereas it was constant at 1 torr. It is suggested that optimum detection scheme as opposed to generation of strong plasma is more important in the low pressure LIBS study. The laser energy required for aluminum detection was only 3.664 mJ/pulse at 1 torr. The key aspect of this successful detection is the combined ablated mass confinement and the low pressure detection. This method has the potential to lead the detection of minor elements in metals at an increased sensitivity.

Choi, Soo Jin; Lee, Kang-jae; Yoh, Jack J.

2014-07-01

31

Patterned time-orbiting potentials for the confinement and assembly of magnetic dipoles  

NASA Astrophysics Data System (ADS)

We present an all-magnetic scheme for the assembly and study of magnetic dipoles within designed confinement profiles that are activated on micro-patterned permalloy films through a precessing magnetic field. Independent control over the confinement and dipolar interactions is achieved by tuning the strength and orientation of the revolving field. The technique is demonstrated with superparamagnetic microspheres field-driven to assemble into closely packed lattice sheets, quasi-1D and other planar structures expandable into dipolar arrays that mirror the patterned surface motifs.

Chen, A.; Sooryakumar, R.

2013-11-01

32

Patterned time-orbiting potentials for the confinement and assembly of magnetic dipoles.  

PubMed

We present an all-magnetic scheme for the assembly and study of magnetic dipoles within designed confinement profiles that are activated on micro-patterned permalloy films through a precessing magnetic field. Independent control over the confinement and dipolar interactions is achieved by tuning the strength and orientation of the revolving field. The technique is demonstrated with superparamagnetic microspheres field-driven to assemble into closely packed lattice sheets, quasi-1D and other planar structures expandable into dipolar arrays that mirror the patterned surface motifs. PMID:24185093

Chen, A; Sooryakumar, R

2013-01-01

33

Patterned time-orbiting potentials for the confinement and assembly of magnetic dipoles  

PubMed Central

We present an all-magnetic scheme for the assembly and study of magnetic dipoles within designed confinement profiles that are activated on micro-patterned permalloy films through a precessing magnetic field. Independent control over the confinement and dipolar interactions is achieved by tuning the strength and orientation of the revolving field. The technique is demonstrated with superparamagnetic microspheres field-driven to assemble into closely packed lattice sheets, quasi-1D and other planar structures expandable into dipolar arrays that mirror the patterned surface motifs.

Chen, A.; Sooryakumar, R.

2013-01-01

34

Fully three-dimensional, time-dependent numerical simulations of Newtonian and viscoelastic swirling flows in a confined cylinder  

Microsoft Academic Search

Aiming at simulating the viscoelastic flow problems involving three-dimensional, time-dependent complex flow, a fully three-dimensional (3D) numerical method using an implicit finite volume formulation is developed in the cylindrical coordinate system. We focus our attention on the well known swirling flows in a confined cylinder with a rotating bottom lid, and through careful comparisons with the available experimental results, the

S. C Xue; N Phan-Thien; R. I Tanner

1999-01-01

35

Measuring time of flight of fusion products in an inertial electrostatic confinement fusion device for spatial profiling of fusion reactions  

SciTech Connect

A new diagnostic has been developed that uses the time of flight (TOF) of the products from a nuclear fusion reaction to determine the location where the fusion reaction occurred. The TOF diagnostic uses charged particle detectors on opposing sides of the inertial electrostatic confinement (IEC) device that are coupled to high resolution timing electronics to measure the spatial profile of fusion reactions occurring between the two charged particle detectors. This diagnostic was constructed and tested by the University of Wisconsin-Madison Inertial Electrostatic Confinement Fusion Group in the IEC device, HOMER, which accelerates deuterium ions to fusion relevant energies in a high voltage ({approx}100 kV), spherically symmetric, electrostatic potential well [J. F. Santarius, G. L. Kulcinski, R. P. Ashley, D. R. Boris, B. B. Cipiti, S. K. Murali, G. R. Piefer, R. F. Radel, T. E. Radel, and A. L. Wehmeyer, Fusion Sci. Technol. 47, 1238 (2005)]. The TOF diagnostic detects the products of D(d,p)T reactions and determines where along a chord through the device the fusion event occurred. The diagnostic is also capable of using charged particle spectroscopy to determine the Doppler shift imparted to the fusion products by the center of mass energy of the fusion reactants. The TOF diagnostic is thus able to collect spatial profiles of the fusion reaction density along a chord through the device, coupled with the center of mass energy of the reactions occurring at each location. This provides levels of diagnostic detail never before achieved on an IEC device.

Donovan, D. C. [Sandia National Laboratories, 7011 East Avenue, Livermore, California 94550 (United States); Boris, D. R. [Naval Research Laboratory, 4555 Overlook Avenue, South West, Washington, DC 20375 (United States); Kulcinski, G. L.; Santarius, J. F. [Fusion Technology Institute, University of Wisconsin-Madison, 1500 Engineering Drive, Madison, Wisconsin 53706 (United States); Piefer, G. R. [Phoenix Nuclear Labs, 2555 Industrial Drive, Madison, Wisconsin 53713 (United States)

2013-03-15

36

Measuring time of flight of fusion products in an inertial electrostatic confinement fusion device for spatial profiling of fusion reactions.  

PubMed

A new diagnostic has been developed that uses the time of flight (TOF) of the products from a nuclear fusion reaction to determine the location where the fusion reaction occurred. The TOF diagnostic uses charged particle detectors on opposing sides of the inertial electrostatic confinement (IEC) device that are coupled to high resolution timing electronics to measure the spatial profile of fusion reactions occurring between the two charged particle detectors. This diagnostic was constructed and tested by the University of Wisconsin-Madison Inertial Electrostatic Confinement Fusion Group in the IEC device, HOMER, which accelerates deuterium ions to fusion relevant energies in a high voltage (?100 kV), spherically symmetric, electrostatic potential well [J. F. Santarius, G. L. Kulcinski, R. P. Ashley, D. R. Boris, B. B. Cipiti, S. K. Murali, G. R. Piefer, R. F. Radel, T. E. Radel, and A. L. Wehmeyer, Fusion Sci. Technol. 47, 1238 (2005)]. The TOF diagnostic detects the products of D(d,p)T reactions and determines where along a chord through the device the fusion event occurred. The diagnostic is also capable of using charged particle spectroscopy to determine the Doppler shift imparted to the fusion products by the center of mass energy of the fusion reactants. The TOF diagnostic is thus able to collect spatial profiles of the fusion reaction density along a chord through the device, coupled with the center of mass energy of the reactions occurring at each location. This provides levels of diagnostic detail never before achieved on an IEC device. PMID:23556815

Donovan, D C; Boris, D R; Kulcinski, G L; Santarius, J F; Piefer, G R

2013-03-01

37

Time Dependent Filamentation and Stimulated Brillouin Forward Scattering in Inertial Confinement Fusion Plasmas  

Microsoft Academic Search

Numerical simulations of the temporal evolution of laser light filamentation and stimulated Brillouin forward scattering (SBFS) in plasmas, under conditions that are relevant to laser fusion, are presented and analyzed. Long term unsteady behavior of filaments is observed to be the norm. Temporal and spatial incoherence due to filamentation and SBFS are impressed upon time-independent incident laser beams. The bandwidth

Andrew J. Schmitt

38

Real-time description of parton-hadron conversion and confinement dynamics  

Microsoft Academic Search

We propose a new and universal approach to the hadronization problem that incorporates both partonic and hadronic degrees of freedom in their respective domains of relevance, and that describes the conversion between them within a kinetic field theory formulation in real time and full seven-dimensional phase space. We construct a scale-dependent effective theory that reduces to perturbative QCD with its

John Ellis; Klaus Geiger

1995-01-01

39

Real-time description of parton-hadron conversion and confinement dynamics  

Microsoft Academic Search

We propose a new and universal approach to the hadronization problem that incorpo- rates both partonic and hadronic degrees of freedom in their respective domains of relevance, and that describes the conversion between them within a kinetic field theory formulation in real time and full 7-dimensional phase space. We construct a scale-dependent effective theory that reduces to perturbative QCD with

K. Geiger; J. Ellis

1995-01-01

40

A diamond detector for inertial confinement fusion X-ray bang-time measurements at the National Ignition Facility  

SciTech Connect

An instrument has been developed to measure X-ray bang-time for inertial confinement fusion capsules; the time interval between the start of the laser pulse and peak X-ray emission from the fuel core. The instrument comprises chemical vapor deposited polycrystalline diamond photoconductive X-ray detectors with highly ordered pyrolytic graphite X-ray monochromator crystals at the input. Capsule bang-time can be measured in the presence of relatively high thermal and hard X-ray background components due to the selective band pass of the crystals combined with direct and indirect X-ray shielding of the detector elements. A five channel system is being commissioned at the National Ignition Facility at Lawrence Livermore National Laboratory for implosion optimization measurements as part of the National Ignition Campaign. Characteristics of the instrument have been measured demonstrating that X-ray bang-time can be measured with {+-} 30ps precision, characterizing the soft X-ray drive to +/- 1eV or 1.5%.

MacPhee, A G; Brown, C; Burns, S; Celeste, J; Glenzer, S H; Hey, D; Jones, O S; Landen, O; Mackinnon, A J; Meezan, N; Parker, J; Edgell, D; Glebov, V Y; Kilkenny, J; Kimbrough, J

2010-11-09

41

Real-time plasma control in a dual-frequency, confined plasma etcher  

SciTech Connect

The physics issues of developing model-based control of plasma etching are presented. A novel methodology for incorporating real-time model-based control of plasma processing systems is developed. The methodology is developed for control of two dependent variables (ion flux and chemical densities) by two independent controls (27 MHz power and O{sub 2} flow). A phenomenological physics model of the nonlinear coupling between the independent controls and the dependent variables of the plasma is presented. By using a design of experiment, the functional dependencies of the response surface are determined. In conjunction with the physical model, the dependencies are used to deconvolve the sensor signals onto the control inputs, allowing compensation of the interaction between control paths. The compensated sensor signals and compensated set-points are then used as inputs to proportional-integral-derivative controllers to adjust radio frequency power and oxygen flow to yield the desired ion flux and chemical density. To illustrate the methodology, model-based real-time control is realized in a commercial semiconductor dielectric etch chamber. The two radio frequency symmetric diode operates with typical commercial fluorocarbon feed-gas mixtures (Ar/O{sub 2}/C{sub 4}F{sub 8}). Key parameters for dielectric etching are known to include ion flux to the surface and surface flux of oxygen containing species. Control is demonstrated using diagnostics of electrode-surface ion current, and chemical densities of O, O{sub 2}, and CO measured by optical emission spectrometry and/or mass spectrometry. Using our model-based real-time control, the set-point tracking accuracy to changes in chemical species density and ion flux is enhanced.

Milosavljevic, V. [PRL, School of Physics and NCPST, Dublin City University, Dublin 9 (Ireland); Faculty of Physics, University of Belgrade, P.O.B. 368, Belgrade (Serbia); Ellingboe, A. R.; Gaman, C. [PRL, School of Physics and NCPST, Dublin City University, Dublin 9 (Ireland); Ringwood, J. V. [Department of Electronic Engineering, NUI Maynooth, Maynooth, Co., Kildare (Ireland)

2008-04-15

42

Time-dependent behavior of magnetic fields confined by conducting walls  

SciTech Connect

An equation is derived which describes the total current flowing in a moving conducting surface surrounding a magnetic field, where diffusion of the field into the conductor is taken into account. Analytic and numerical solutions of the current equation are obtained for the cases of exponential and linear compression of the magnetic field with time, respectively. It is assumed that the electrical conductivity is constant, that the conducting surfaces are axially symmetric, and that the thickness and radius of curvature of the conducting walls is large compared with the effective depth of penetration of the field.

Kidder, R.E.; Cecil, A.B.

1983-03-09

43

Time resolved laser-induced fluorescence of electrosprayed ions confined in a linear quadrupole trap  

SciTech Connect

We have designed and constructed a linear quadrupole ion trap for the measurement of laser-induced fluorescence (LIF) of mass selected gas-phase ions produced by electrospray ionization. The instrument consists of a simple electrospray source, radiofrequency octopole guide, a dc quadrupole bender, a quadrupole mass filter, the linear quadrupole trap (which is equipped with optics for LIF collection and a channeltron ion detector), and several multielement focusing lenses. With this instrument, the LIF decay lifetime of gas-phase Rhodamine 640 radical cations is determined for the first time.

Friedrich, Jochen; Fu Jinmei; Hendrickson, Christopher L.; Marshall, Alan G.; Wang Yisheng [Ion Cyclotron Resonance Program, National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac Drive, Tallahassee, Florida 32310-4005 (United States); Institute of Atomic and Molecular Sciences, Academia Sinica, P. O. Box 23-166, Taipei, Taiwan (China)

2004-11-01

44

Time-resolved ten-channel monochromatic imaging of inertial confinement fusion plasmas.  

PubMed

We report on what we believe to be the first use of toroidally bent crystals to record two-dimensional, spatially resolved, monochromatic images of laser-produced fusion plasmas combined with a 34-ps fast x-ray framing camera. An array of five toroidal silicon (311) and five toroidal germanium (311) crystals was developed. The imaging properties of the geometries are checked by a ray-tracing program and are compared with experimental results. The total imaging system (crystal and detector) provides an experimentally measured spatial resolution better than 15 mum. Time histories for the hydrogenlike argon emission and the heliumlike argon emission of fusion pellets driven with the GEKKO XII glass laser system are presented. PMID:18354590

Uschmann, I; Fujita, K; Niki, I; Butzbach, R; Nishimura, H; Funakura, J; Nakai, M; Förster, E; Mima, K

2000-11-01

45

Invariance principles and plasma confinement  

Microsoft Academic Search

If the equations that describe the observed anomalous transport in magnetic confinement systems are invariant under a scale transformation then any confinement time calculated from them must exhibit the same invariance, no matter how intractable the calculation. This principle places constraints on the form of the confinement time scaling which are characteristic of the plasma model represented by the equations.

J. W. Connor

1988-01-01

46

Development of a Complex, Time-Shared, Perceptual-Motor Skills Task for Use in Studies of Isolation and Confinement.  

National Technical Information Service (NTIS)

Detailed information is presented about a complex perceptual-motor skills task designed for use in the Naval Medical Research Institute's studies of isolation and confinement. Pilot data are presented demonstrating: (1) that the fully automated task is eq...

S. Smith

1966-01-01

47

Time evolution of filamentation and self-generated fields in the coronae of directly driven inertial-confinement fusion capsules  

SciTech Connect

Time-gated radiography with monoenergetic 15-MeV protons, 3-MeV protons, and 4-MeV alpha particles has revealed a rich and complex evolution of electromagnetic field structures in and around imploding, directly driven inertial-confinement fusion (ICF) targets at the OMEGA laser facility. Plastic-shell capsules and solid plastic spheres were imaged during and after irradiation with ICF-relevant laser drive (up to 6 x 10{sup 14} W/cm{sup 2}). Radial filaments appeared while the laser was on; they filled, and were frozen into, the out-flowing corona, persisting until well after the end of the laser drive. Data from specially designed experiments indicate that the filaments were not generated by two-plasmon-decay instabilities or by Rayleigh-Taylor instabilities associated with shell acceleration. Before the onset of visible filamentation, quasi-spherical field structures appeared outside the capsule in the images in a form that suggests outgoing shells of net positive charge. We conjecture that these discrete shells are related to multiple peaks seen previously in the spectra of protons ablated from the targets.

Seguin, F. H.; Li, C. K.; Manuel, M. J.-E.; Rinderknecht, H. G.; Sinenian, N.; Frenje, J. A.; Rygg, J. R.; Hicks, D. G.; Petrasso, R. D. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Delettrez, J.; Betti, R.; Marshall, F. J.; Smalyuk, V. A. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States)

2012-01-15

48

Time evolution of filamentation and self-generated fields in the coronae of directly driven inertial-confinement fusion capsules  

NASA Astrophysics Data System (ADS)

Time-gated radiography with monoenergetic 15-MeV protons, 3-MeV protons, and 4-MeV alpha particles has revealed a rich and complex evolution of electromagnetic field structures in and around imploding, directly driven inertial-confinement fusion (ICF) targets at the OMEGA laser facility. Plastic-shell capsules and solid plastic spheres were imaged during and after irradiation with ICF-relevant laser drive (up to 6 × 1014 W/cm2). Radial filaments appeared while the laser was on; they filled, and were frozen into, the out-flowing corona, persisting until well after the end of the laser drive. Data from specially designed experiments indicate that the filaments were not generated by two-plasmon-decay instabilities or by Rayleigh-Taylor instabilities associated with shell acceleration. Before the onset of visible filamentation, quasi-spherical field structures appeared outside the capsule in the images in a form that suggests outgoing shells of net positive charge. We conjecture that these discrete shells are related to multiple peaks seen previously in the spectra of protons ablated from the targets.

Séguin, F. H.; Li, C. K.; Manuel, M. J.-E.; Rinderknecht, H. G.; Sinenian, N.; Frenje, J. A.; Rygg, J. R.; Hicks, D. G.; Petrasso, R. D.; Delettrez, J.; Betti, R.; Marshall, F. J.; Smalyuk, V. A.

2012-01-01

49

Time-dependent Poiseuille flow of a viscous compressible fluid confined between two planar walls with dynamic partial slip boundary condition.  

PubMed

Time-dependent Poiseuille flow of a viscous compressible fluid confined between two planar walls is studied for a partial slip boundary condition with frequency-dependent slip length. After an initial uniform impulse parallel to the walls, the flow pattern quickly becomes nearly parabolic. For a narrow gap, a dynamic slip length can lead to damped oscillations of total fluid momentum. PMID:23005201

Felderhof, B U

2012-06-01

50

Correcting for bias of molecular confinement parameters induced by small-time-series sample sizes in single-molecule trajectories containing measurement noise.  

PubMed

Several single-molecule studies aim to reliably extract parameters characterizing molecular confinement or transient kinetic trapping from experimental observations. Pioneering works from single-particle tracking (SPT) in membrane diffusion studies [Kusumi et al., Biophys. J. 65, 2021 (1993)] appealed to mean square displacement (MSD) tools for extracting diffusivity and other parameters quantifying the degree of confinement. More recently, the practical utility of systematically treating multiple noise sources (including noise induced by random photon counts) through likelihood techniques has been more broadly realized in the SPT community. However, bias induced by finite-time-series sample sizes (unavoidable in practice) has not received great attention. Mitigating parameter bias induced by finite sampling is important to any scientific endeavor aiming for high accuracy, but correcting for bias is also often an important step in the construction of optimal parameter estimates. In this article, it is demonstrated how a popular model of confinement can be corrected for finite-sample bias in situations where the underlying data exhibit Brownian diffusion and observations are measured with non-negligible experimental noise (e.g., noise induced by finite photon counts). The work of Tang and Chen [J. Econometrics 149, 65 (2009)] is extended to correct for bias in the estimated "corral radius" (a parameter commonly used to quantify confinement in SPT studies) in the presence of measurement noise. It is shown that the approach presented is capable of reliably extracting the corral radius using only hundreds of discretely sampled observations in situations where other methods (including MSD and Bayesian techniques) would encounter serious difficulties. The ability to accurately statistically characterize transient confinement suggests additional techniques for quantifying confined and/or hop diffusion in complex environments. PMID:23944492

Calderon, Christopher P

2013-07-01

51

Optical interferometric studies of a confined liquid free surface: meniscus-effect compensation and time evolution of the surface  

Microsoft Academic Search

A fruitful approach to the studies of a liquid free surface is demonstrated. Using optical interferential techniques, the free surface of nonvolatile and volatile confined liquids are analyzed. Various wall container types are investigated. Besides the classical plane wall, experiments are performed by using cylindrical and toroidal walls. In these last cases, the meniscus effect that affects the free surface

Lea V. Bourimborde; Alejandro Tonso; Lia M. Zerbino; Mario Garavaglia

1996-01-01

52

Bacteria in Confined Spaces  

NASA Astrophysics Data System (ADS)

Bacterial cells can display differentiation between several developmental pathways, from planktonic to matrix-producing, depending upon the colony conditions. We study the confinement of bacteria in hydrogels as well as in liquid-liquid double emulsion droplets and observe the growth and morphology of these colonies as a function of time and environment. Our results can give insight into the behavior of bacterial colonies in confined spaces that can have applications in the areas of food science, cosmetics, and medicine.

Wilking, Connie; Weitz, David

2010-03-01

53

The confining trailing string  

NASA Astrophysics Data System (ADS)

We extend the holographic trailing string picture of a heavy quark to the case of a bulk geometry dual to a confining gauge theory. We compute the classical trailing confining string solution for a static as well as a uniformly moving quark. The trailing string is infinitely extended and approaches a confining horizon, situated at a critical value of the radial coordinate, along one of the space-time directions, breaking boundary rotational invariance. We compute the equations for the fluctuations around the classical solutions, which are used to obtain boundary force correlators controlling the Langevin dynamics of the quark. The imaginary part of the correlators has a non-trivial low-frequency limit, which gives rise to a viscous friction coefficient induced by the confining vacuum. The vacuum correlators are used to define finite-temperature dressed Langevin correlators with an appropriate high-frequency behavior.

Kiritsis, Elias; Mazzanti, Liuba; Nitti, Francesco

2014-02-01

54

Isothermal Confinement  

NASA Astrophysics Data System (ADS)

The concept of isothermal confinement is presented. The idea is a revival of the early magnetic fusion concepts with new insight. The plasma core is confined magnetically and is surrounded by a quasi-vacuum region. The temperature of the core is uniform and the turbulence associated with the temperature gradient is absent. The quasi-vacuum region is unstable against the pressure gradient and the turbulent transport rate is much larger than that of the core. Two modes of operation, pulsed and steady state, are considered. Recent experimental results in LHD and CDX-U appear to support the concept.

Ohkawa, Tihiro

55

Confined direct analysis in real time ion source and its applications in analysis of volatile organic compounds of Citrus limon (lemon) and Allium cepa (onion).  

PubMed

The DART (direct analysis in real time) ion source is a novel atmospheric pressure ionization technique that enables efficient ionization of gases, liquids and solids with high throughput. A major limit to its wider application in the analysis of gases is its poor detection sensitivity caused by open-air sampling. In this study, a confined interface between the DART ion source outlet and mass spectrometer sampling orifice was developed, where the plasma generated by the atmospheric pressure glow discharge collides and ionizes gas-phase molecules in a Tee-shaped flow tube instead of in open air. It leads to significant increase of collision reaction probability between high energy metastable molecules and analytes. The experimental results show that the ionization efficiency was increased at least by two orders of magnitude. This technique was then applied in the real time analysis of volatile organic compounds (VOCs) of Citrus Limon (lemon) and wounded Allium Cepa (onion). The confined DART ion source was proved to be a powerful tool for the studies of plant metabolomics. PMID:22499194

Li, Yue

2012-05-30

56

ATR confinement leakage determination  

SciTech Connect

The air leakage rate from the Advanced Test Reactor (ATR) confinement is an important parameter in estimating hypothesized accidental releases of radiation to the environment. The leakage rate must be determined periodically to assure that the confinement has not degraded with time and such determination is one of the technical safety requirements of ATR operation. This paper reviews the methods of confinement leakage determination and presents an analysis of leakage determination under windy conditions, which can complicate the interpretation of the determined leakage rates. The paper also presents results of analyses of building air exchange under windy conditions. High wind can enhance air exchange and this could increase the release rates of radioisotopes following an accident.

Kuan, P.; Buescher, B.J.

1998-06-01

57

A novel method for modeling the neutron time of flight detector response in current mode to inertial confinement fusion experiments (invited)  

NASA Astrophysics Data System (ADS)

A novel method for modeling the neutron time of flight (nTOF) detector response in current mode for inertial confinement fusion experiments has been applied to the on-axis nTOF detectors located in the basement of the Z-Facility. It will be shown that this method can identify sources of neutron scattering, and is useful for predicting detector responses in future experimental configurations, and for identifying potential sources of neutron scattering when experimental set-ups change. This method can also provide insight on how much broadening neutron scattering contributes to the primary signals, which is then subtracted from them. Detector time responses are deconvolved from the signals, allowing a transformation from dN/dt to dN/dE, extracting neutron spectra at each detector location; these spectra are proportional to the absolute yield.

Nelson, A. J.; Ruiz, C. L.; Cooper, G. W.; Chandler, G. A.; Fehl, D. L.; Hahn, K. D.; Leeper, R. J.; Smelser, R.; Torres, J. A.

2012-10-01

58

A novel method for modeling the neutron time of flight detector response in current mode to inertial confinement fusion experiments (invited).  

PubMed

A novel method for modeling the neutron time of flight (nTOF) detector response in current mode for inertial confinement fusion experiments has been applied to the on-axis nTOF detectors located in the basement of the Z-Facility. It will be shown that this method can identify sources of neutron scattering, and is useful for predicting detector responses in future experimental configurations, and for identifying potential sources of neutron scattering when experimental set-ups change. This method can also provide insight on how much broadening neutron scattering contributes to the primary signals, which is then subtracted from them. Detector time responses are deconvolved from the signals, allowing a transformation from dN/dt to dN/dE, extracting neutron spectra at each detector location; these spectra are proportional to the absolute yield. PMID:23126918

Nelson, A J; Ruiz, C L; Cooper, G W; Chandler, G A; Fehl, D L; Hahn, K D; Leeper, R J; Smelser, R; Torres, J A

2012-10-01

59

A novel method for modeling the neutron time of flight detector response in current mode to inertial confinement fusion experiments (invited)  

SciTech Connect

A novel method for modeling the neutron time of flight (nTOF) detector response in current mode for inertial confinement fusion experiments has been applied to the on-axis nTOF detectors located in the basement of the Z-Facility. It will be shown that this method can identify sources of neutron scattering, and is useful for predicting detector responses in future experimental configurations, and for identifying potential sources of neutron scattering when experimental set-ups change. This method can also provide insight on how much broadening neutron scattering contributes to the primary signals, which is then subtracted from them. Detector time responses are deconvolved from the signals, allowing a transformation from dN/dt to dN/dE, extracting neutron spectra at each detector location; these spectra are proportional to the absolute yield.

Nelson, A. J.; Cooper, G. W. [Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131 (United States); Ruiz, C. L.; Chandler, G. A.; Fehl, D. L.; Hahn, K. D.; Leeper, R. J.; Smelser, R.; Torres, J. A. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1196 (United States)

2012-10-15

60

Estimates of confinement time and energy gain for plasma liner driven magnetoinertial fusion using an analytic self-similar converging shock model  

NASA Astrophysics Data System (ADS)

Plasma liner driven magnetoinertial fusion (PLMIF) is a fusion energy concept that utilizes an imploding plasma liner to shock heat and compress a magnetized target plasma to fusion conditions. The fusion burn fraction is linearly proportional to the confinement (or ``dwell'') time of the liner-target system at peak compression, and therefore it is important to estimate the dwell time accurately in order to assess the fusion energy yield and gain. In this work, the dwell time has been estimated using the exact solution to a self-similar converging shock model. The dwell time was found to be determined by the sum of the outgoing shock and rarefaction times through the plasma liner at peak compression, and for chosen PLMIF conditions the dwell time was on the order of 1 ?s. In addition, we show that the engineering gain, i.e., the total energy extracted as electricity (from fusion plus expanded liner energy) divided by the electrical energy required to implode the liner, exceeds unity for a wide range of liner thicknesses and specific heat ratios.

Cassibry, J. T.; Cortez, R. J.; Hsu, S. C.; Witherspoon, F. D.

2009-11-01

61

Use of microarray technology to assess the time course of liver stress response after confinement exposure in gilthead sea bream (Sparus aurata L.)  

PubMed Central

Background Selection programs for growth and stress traits in cultured fish are fundamental to the improvement of aquaculture production. The gilthead sea bream (Sparus aurata) is the main aquacultured species in the Mediterranean area and there is considerable interest in the genetic improvement of this species. With the aim of increasing the genomic resources in gilthead sea bream and identifying genes and mechanisms underlying the physiology of the stress response, we developed a cDNA microarray for gilthead sea bream that is enriched by suppression substractive hybridization with stress and immunorelevant genes. This microarray is used to analyze the dynamics of gilthead sea bream liver expression profile after confinement exposure. Results Groups of confined and control juvenile fish were sampled at 6, 24, 72 and 120 h post exposure. GeneSpring analyses identified 202 annotated genes that appeared differentially expressed at least at one sampling time (P < 0.05). Gene expression results were validated by quantitative PCR of 10 target genes, and K-means clustering of differently expressed genes identified four major temporal gene expression profiles. Set 1 encompassed a rapid metabolic readjustment with enhanced uptake and intracellular transport of fatty acids as metabolic fuels. Set 2 was associated with a wide variety of tissue repair and remodeling processes that were mostly mediated by the stress response of the endoplasmic reticulum (ER). Sets 3 and 4 encompassed the re-establishment of cellular homeostasis with increased intracellular trafficking and scavenging of reactive oxygen species (ROS), accompanied by a bidirectional regulation of the immune system and a general decline of ROS production. Conclusions Collectively, these findings show the complex nature of the adaptive stress response with a clear indication that the ER is an important control point for homeostatic adjustments. The study also identifies metabolic pathways which could be analyzed in greater detail to provide new insights regarding the transcriptional regulation of the stress response in fish.

2010-01-01

62

Thermonuclear ignition in inertial confinement fusion and comparison with magnetic confinement  

Microsoft Academic Search

The physics of thermonuclear ignition in inertial confinement fusion (ICF) is presented in the familiar frame of a Lawson-type criterion. The product of the plasma pressure and confinement time Ptau for ICF is cast in terms of measurable parameters and its value is estimated for cryogenic implosions. An overall ignition parameter chi including pressure, confinement time, and temperature is derived

R. Betti; P. Y. Chang; B. K. Spears; K. S. Anderson; J. Edwards; M. Fatenejad; J. D. Lindl; R. L. McCrory; R. Nora; D. Shvarts

2010-01-01

63

Study of the 3D Coronal Magnetic Field of Active Region 11117 Around the Time of a Confined Flare Using a Data-Driven CESE-MHD Model  

NASA Astrophysics Data System (ADS)

Non-potentiality of the solar coronal magnetic field accounts for the solar explosion like flares and CMEs. We apply a data-driven CESE-MHD model to investigate the three-dimensional (3D) coronal magnetic field of NOAA active region (AR) 11117 around the time of a C-class confined flare occurred on 2010 October 25. The CESE-MHD model, based on the spacetime conservation-element and solution-element scheme, is designed to focus on the magnetic-field evolution and to consider a simplified solar atomsphere with finite plasma ?. Magnetic vector-field data derived from the observations at the photoshpere is inputted directly to constrain the model. Assuming that the dynamic evolution of the coronal magnetic field can be approximated by successive equilibria, we solve a time sequence of MHD equilibria basing on a set of vector magnetograms for AR 11117 taken by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamic Observatory (SDO) around the time of flare. The model qualitatively reproduces the basic structures of the 3D magnetic field, as supported by the visual similarity between the field lines and the coronal loops observed by the Atmospheric Imaging Assembly (AIA), which shows that the coronal field can indeed be well characterized by the MHD equilibrium in most time. The magnetic configuration changes very limited during the studied time interval of two hours. A topological analysis reveals that the small flare is correlated with a bald patch (BP, where the magnetic field is tangent to the photoshpere), suggesting that the energy release of the flare can be understood by magnetic reconnection associated with the BP separatrices. The total magnetic flux and energy keep increasing slightly in spite of the flare, while the magnetic free energy drops during the flare with an amount of 1.7 × 1030 erg, which can be interpreted as the energy budget released by the minor C-class flare.

Jiang, C.; Feng, X.; Wu, S.; Hu, Q.

2012-12-01

64

Long-term effects of dredging operations program. Collation and interpretation of data for Times Beach confined disposal facility, Buffalo, New York. Final report  

SciTech Connect

This interim report, collates all data gathered for the Times Beach confined disposal facility (CDF), Buffalo, New York. This purpose of the studies at the CDF was to determine the mobility and potential hazard of contaminants known to be in the dredged material placed at Times Beach by sampling and analyzing various components of the developing ecosystems. Upland, wetland, and aquatic areas are represented within the CDF and, for each area, inventories of colonizing biota were made and samples collected for measurement of heavy metals and organic compound contaminants. Samples of dredged material, vegetation, and soil-dwelling invertebrates, and vertebrates have been collected and heavy metal concentrations measured. Results suggest that the persistent contaminants, particularly cadmium, are concentrating in the leaf litter zone and moving into the detritivorous invertebrates. Highest concentrations of heavy metals were noted in earthworms. Earth worms, millipedes, woodlice, and spiders appeared to be target organisms for accumulation of heavy metals, and these groups contained higher concentrations of copper and cadmium than the other groups. Polychlorinated biphenyl (PCB) and polynuclear aromatic hydrocarbon contaminants in the dredged material were below machine detection limits in the vertebrate top-predators. Contaminant concentrations in water from ground water wells were below guidance limits.

Stafford, E.A.; Simmers, J.W.; Rhett, R.G.; Brown, C.P.

1991-06-01

65

Confined Hard Disk System Model  

NSDL National Science Digital Library

The Confined Hard Disk System is an idealized statistical mechanics model that simulates a two-dimensional system of hard disks confined to a box with a constant temperature thermal reservoir at one end and a movable piston at the other. Slow-moving particles are color-coded as blue and fast particles are color-coded as yellow. The model computes and plots the time evolution of the kinetic energy K per particle, the pressure P, and the volume V. The model also displays histograms and mean values of these quantities. The Confined Hard Disk System was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_hd_ConfinedHardDiskSystem.jar file will run the program if Java is installed.

Christian, Wolfgang

2010-12-27

66

Effect of confinement during cookoff of TATB  

NASA Astrophysics Data System (ADS)

In practical scenarios, cookoff of explosives is a three-dimensional transient phenomenon where the rate limiting reactions may occur either in the condensed or gas phase. The effects of confinement are more dramatic when the rate-limiting reactions occur in the gas phase. Explosives can be self-confined, where the decomposing gases are contained within non-permeable regions of the explosive, or confined by a metal or composite container. In triaminotrinitrobenzene (TATB) based explosives, self-confinement is prevalent in plastic bonded explosives at full density. The time-to-ignition can be delayed by orders of magnitude if the reactive gases leave the confining apparatus. Delays in ignition can also occur when the confining apparatus has excess gas volume or ullage. Understanding the effects of confinement is required to accurately model explosive cookoff at various scales ranging from small laboratory experiments to large real systems.

Hobbs, M. L.; Kaneshige, M. J.

2014-05-01

67

Spatial profiling using a Time of Flight Diagnostic and applications of deuterim-deuterium fusion in Inertial Electrostatic Confinement fusion devices  

NASA Astrophysics Data System (ADS)

The Inertial Electrostatic Confinement (IEC) Fusion Research Group at the University of Wisconsin-Madison utilizes IEC devices as small-scale neutron generators using D-D fusion to create 2.45 MeV neutrons for the purpose of detecting clandestine material. Detection of explosives in particular can be accomplished using thermal neutron capture methods to identify characteristic nitrogen signatures in explosive material. Research has been conducted to increase reliability of detection, decrease interrogation time, and increase the steady-state operational time. Efforts have also been made to increase the neutron production rate of the device. Optimization studies have varied the configuration and design of the electrodes and have resulted in system configurations with up to 50 percent higher neutron production rates than have previously been utilized. A new feedthrough design has been constructed that is intended to increase the maximum operating voltage from 175 kV with the previous feedthrough to 300 kV. Neutron production rates scale almost linearly with both current and voltage, so the IEC device will be capable of operation at higher neutron producing regimes than have ever before been achieved. The optimization efforts involve the use of several new diagnostic tools developed at UW, which are the Fusion Ion Doppler (FIDO) Diagnostic and the Time of Flight (TOF) Diagnostic. FIDO provides the energy spectra of the charged fusion products and reactants created in the IEC device. The FIDO Diagnostic was originally only capable of studying D-D fusion, but with recent advancements is now able to study both D-D and D-3He fusion. The TOF Diagnostic provides spatial information along with the energy resolution of where the fusion reactions are occurring in the IEC device. Development of the diagnostics has involved the implementation of timing electronics, alignment systems, data acquisition software, computational post-processing, and upgrades to the experimental facility. A significant rise in the concentration of fusion events was found outside of the anode, believed to be due in part from negative ions. The FIDO and TOF Diagnostics have proven to be valuable additions to the study of IEC devices and have greatly advanced IEC operation and theory.

Donovan, David C.

68

A Review of Quantum Confinement  

SciTech Connect

A succinct history of the Confined Atom problem is presented. The hydrogen atom confined to the centre of an impenetrable sphere counts amongst the exactly soluble problems of physics, alongside much more noted exact solutions such as Black Body Radiation and the free Hydrogen atom in absence of any radiation field. It shares with them the disadvantage of being an idealisation, while at the same time encapsulating in a simple way particular aspects of physical reality. The problem was first formulated by Sommerfeld and Welker - henceforth cited as SW - in connection with the behaviour of atoms at very high pressures, and the solution was published on the occasion of Pauli's 60th birthday celebration. At the time, it seemed that there was not much other connection with physical reality beyond a few simple aspects connected to the properties of atoms in solids, for which more appropriate models were soon developed. Thus, confined atoms attracted little attention until the advent of the metallofullerene, which provided the first example of a confined atom with properties quite closely related to those originally considered by SW. Since then, the problem has received much more attention, and many more new features of quantum confinement, quantum compression, the quantum Faraday cage, electronic reorganisation, cavity resonances, etc have been described, which are relevant to real systems. Also, a number of other situations have been uncovered experimentally to which quantum confinement is relevant. Thus, studies of the confined atom are now more numerous, and have been extended both in terms of the models used and the systems to which they can be applied. Connections to thermodynamics are explored through the properties of a confined two-level atom adapted from Einstein's celebrated model, and issues of dynamical screening of electromagnetic radiation by the confining shell are discussed in connection with the Faraday cage produced by a confining conducting shell. The conclusions are shown to be relevant to a proposed 'quantum computer'. The description of the actual geometry of C{sub 60}, as opposed to a purely spherical approximation, leads to some qualification of the computed results.

Connerade, Jean-Patrick [Quantum Optics and Laser Science Group, Physics Department, Imperial College, London (United Kingdom)

2009-12-03

69

Modeling the time variation of beam-grid fusion reaction rates in an Inertial Electrostatic Confinement device driven by a ring-shaped magnetron ion source  

Microsoft Academic Search

We use the two-dimensional analysis code KUAD2 to simulate D^{+_{2}} trajectories in an Inertial Electrostatic Confinement (IEC) device driven by a ring-shaped magnetron ion source (RS-MIS). This aims to maximize the path length lambdaCX for ion-gas charge exchange by operating at just units of mPa D2 gas pressures; however, under these conditions simulations reveal a surprisingly small path length for

J. Kipritidis; K. Masuda; T. Kajiwara; Y. Yamagaki; K. Nagasaki

2011-01-01

70

Momentum Confinement at Low Torque  

SciTech Connect

Momentum confinement was investigated on DIII-D as a function of applied neutral beam torque at constant normalized {beta}{sub N}, by varying the mix of co (parallel to the plasma current) and counter neutral beams. Under balanced neutral beam injection (i.e. zero total torque to the plasma), the plasma maintains a significant rotation in the co-direction. This 'intrinsic' rotation can be modeled as being due to an offset in the applied torque (i.e. an 'anomalous torque'). This anomalous torque appears to have a magnitude comparable to one co-neutral beam source. The presence of such an anomalous torque source must be taken into account to obtain meaningful quantities describing momentum transport, such as the global momentum confinement time and local diffusivities. Studies of the mechanical angular momentum in ELMing H-mode plasmas with elevated q{sub min} show that the momentum confinement time improves as the torque is reduced. In hybrid plasmas, the opposite effect is observed, namely that momentum confinement improves at high torque/rotation. The relative importance of E x B shearing between the two is modeled using GLF23 and may suggest a possible explanation.

Solomon, W M; Burrell, K H; deGrassie, J S; Budny, R; Groebner, R J; Heidbrink, W W; Kinsey, J E; Kramer, G J; Makowski, M A; Mikkelsen, D; Nazikian, R; Petty, C C; Politzer, P A; Scott, S D; Van Zeeland, M A; Zarnstorff, M C

2007-06-26

71

Absence of reptation in highly confined polymers.  

PubMed

We present results of mechanical stress relaxation measurements on polymers confined at the air-water interface in the form of a monolayer. Systematic measurements allow, to our knowledge, for the first time, observation of the scaling of the stress relaxation time of the highly confined polymers as a function of both surface concentration and molecular weight. The observed scaling is found to be very close to that expected for motion of unentangled polymer solutions with hydrodynamic interactions. Our experimental observations thus clearly rule out the possibility of entanglement and hence reptation as a mode of relaxation in such highly confined polymeric systems. PMID:19530789

Srivastava, S; Basu, J K

2009-06-14

72

Plasma confinement in the TMX tandem mirror  

SciTech Connect

Plasma confinement in the Tandem Mirror Experiment (TMX) is described. Axially confining potentials are shown to exist throughout the central 20-cm core of TMX. Axial electron-confinement time is up to 100 times that of single-cell mirror machines. Radial transport of ions is smaller than axial transport near the axis. It has two parts at large radii: nonambipolar, in rough agreement with predictions from resonant-neoclassical transport theory, and ambipolar, observed near the plasma edge under certain conditions, accompanied by a low-frequency, m = 1 instability or strong turbulence.

Hooper, E.B. Jr.; Allen, S.L.; Casper, T.A.

1981-04-29

73

Computer Simulation of Electrostatic Inertial Confinement.  

National Technical Information Service (NTIS)

The technique of numerical plasma simulation is here used to study the behavior of the electrostatic-inertial confinement device. Particle type simulation models calculate the time evolution of the plasma contained within a spherical chamber into which hi...

C. Barnes

1973-01-01

74

Enhancement of confinement in tokamaks  

SciTech Connect

A plausible interpretation of the experimental evidence is that energy confinement in tokamaks is governed by two separate considerations: (1) the need for resistive MHD kink-stability, which limits the permissible range of current profiles - and therefore normally also the range of temperature profiles; and (2) the presence of strongly anomalous microscopic energy transport near the plasma edge, which calibrates the amplitude of the global temperature profile, thus determining the energy confinement time tau/sub E/. Correspondingly, there are two main paths towards the enhancement of tokamak confinement: (1) Configurational optimization, to increase the MHD-stable energy content of the plasma core, can evidently be pursued by varying the cross-sectional shape of the plasma and/or finding stable radial profiles with central q-values substantially below unity - but crossing from ''first'' to ''second'' stability within the peak-pressure region would have the greatest ultimate potential. (2) Suppression of edge turbulence, so as to improve the heat insulation in the outer plasma shell, can be pursued by various local stabilizing techniques, such as use of a poloidal divertor. The present confinement model and initial TFTR pellet-injection results suggest that the introduction of a super-high-density region within the plasma core should be particularly valuable for enhancing ntau/subE/. In D-T operation, a centrally peaked plasma pressure profile could possibly lend itself to alpha-particle-driven entry into the second-stability regime.

Furth, H.P.

1986-05-01

75

Inertial Confinement Fusion.  

National Technical Information Service (NTIS)

In these notes, we discuss inertially confined thermonuclear fusion obtained by means of spherically imploded deuterium-tritium fuel. The emphasis is on the 'inner part' of ICF physics, on the implosion dynamics, central fuel ignition, and energy gain, ra...

J. Meyer-ter-Vehn

1985-01-01

76

STUDY OF THE THREE-DIMENSIONAL CORONAL MAGNETIC FIELD OF ACTIVE REGION 11117 AROUND THE TIME OF A CONFINED FLARE USING A DATA-DRIVEN CESE-MHD MODEL  

SciTech Connect

We apply a data-driven magnetohydrodynamics (MHD) model to investigate the three-dimensional (3D) magnetic field of NOAA active region (AR) 11117 around the time of a C-class confined flare that occurred on 2010 October 25. The MHD model, based on the spacetime conservation-element and solution-element scheme, is designed to focus on the magnetic field evolution and to consider a simplified solar atomsphere with finite plasma {beta}. Magnetic vector-field data derived from the observations at the photosphere is inputted directly to constrain the model. Assuming that the dynamic evolution of the coronal magnetic field can be approximated by successive equilibria, we solve a time sequence of MHD equilibria based on a set of vector magnetograms for AR 11117 taken by the Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory around the time of the flare. The model qualitatively reproduces the basic structures of the 3D magnetic field, as supported by the visual similarity between the field lines and the coronal loops observed by the Atmospheric Imaging Assembly, which shows that the coronal field can indeed be well characterized by the MHD equilibrium in most cases. The magnetic configuration changes very little during the studied time interval of 2 hr. A topological analysis reveals that the small flare is correlated with a bald patch (BP, where the magnetic field is tangent to the photosphere), suggesting that the energy release of the flare can be understood by magnetic reconnection associated with the BP separatrices. The total magnetic flux and energy keep increasing slightly in spite of the flare, while the computed magnetic free energy drops during the flare by {approx}10{sup 30} erg, which seems to be adequate in providing the energy budget of a minor C-class confined flare.

Jiang Chaowei; Feng Xueshang [SIGMA Weather Group, State Key Laboratory for Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190 (China); Wu, S. T.; Hu Qiang, E-mail: cwjiang@spaceweather.ac.cn, E-mail: fengx@spaceweather.ac.cn, E-mail: wus@uah.edu, E-mail: qh0001@uah.edu [Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL 35899 (United States)

2012-11-10

77

Study of the Three-dimensional Coronal Magnetic Field of Active Region 11117 around the Time of a Confined Flare Using a Data-Driven CESE-MHD Model  

NASA Astrophysics Data System (ADS)

We apply a data-driven magnetohydrodynamics (MHD) model to investigate the three-dimensional (3D) magnetic field of NOAA active region (AR) 11117 around the time of a C-class confined flare that occurred on 2010 October 25. The MHD model, based on the spacetime conservation-element and solution-element scheme, is designed to focus on the magnetic field evolution and to consider a simplified solar atomsphere with finite plasma ?. Magnetic vector-field data derived from the observations at the photosphere is inputted directly to constrain the model. Assuming that the dynamic evolution of the coronal magnetic field can be approximated by successive equilibria, we solve a time sequence of MHD equilibria based on a set of vector magnetograms for AR 11117 taken by the Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory around the time of the flare. The model qualitatively reproduces the basic structures of the 3D magnetic field, as supported by the visual similarity between the field lines and the coronal loops observed by the Atmospheric Imaging Assembly, which shows that the coronal field can indeed be well characterized by the MHD equilibrium in most cases. The magnetic configuration changes very little during the studied time interval of 2 hr. A topological analysis reveals that the small flare is correlated with a bald patch (BP, where the magnetic field is tangent to the photosphere), suggesting that the energy release of the flare can be understood by magnetic reconnection associated with the BP separatrices. The total magnetic flux and energy keep increasing slightly in spite of the flare, while the computed magnetic free energy drops during the flare by ~1030 erg, which seems to be adequate in providing the energy budget of a minor C-class confined flare.

Jiang, Chaowei; Feng, Xueshang; Wu, S. T.; Hu, Qiang

2012-11-01

78

Comment on ``Two definitions of the hopping time in a confined fluid of finite particles'' [J. Chem. Phys. 129, 154117 (2008)  

NASA Astrophysics Data System (ADS)

To resolve the disagreement between two calculations for the hopping time divergence exponent of two diffusing hard disks in a narrow channel, Kalinay and Percus propose that the definitions of the hopping time used in the two calculations are not equivalent, which resulted in different exponents. The first is the mean first passage time (MFPT) and is related to the survival probability function S(t) at long time. Bowles, Mon, and Percus solve an approximate Fick-Jacobs equation to produce a MFPT exponent of -3/2. The second is defined by Kalinay and Percus in terms of the short time relaxation of S(t). Kalinay and Percus claim that Mon and Percus used the short time relaxation of the survival function to obtain an exponent of -2 in the numerical solution of the diffusion equation. This is not an accurate description of the Mon and Percus method. To the contrary, the method of Mon and Percus is designed to extract the longest relaxation time constant. In this comment, I discuss this misunderstanding of Kalinay and Percus and show that the explanation for the disagreement with the approximate Fick-Jacob equation predictions is not in the difference of the definitions for the hopping time.

Mon, K. K.

2011-04-01

79

Confined Brownian ratchets  

NASA Astrophysics Data System (ADS)

We analyze the dynamics of Brownian ratchets in a confined environment. The motion of the particles is described by a Fick-Jakobs kinetic equation in which the presence of boundaries is modeled by means of an entropic potential. The cases of a flashing ratchet, a two-state model, and a ratchet under the influence of a temperature gradient are analyzed in detail. We show the emergence of a strong cooperativity between the inherent rectification of the ratchet mechanism and the entropic bias of the fluctuations caused by spatial confinement. Net particle transport may take place in situations where none of those mechanisms leads to rectification when acting individually. The combined rectification mechanisms may lead to bidirectional transport and to new routes to segregation phenomena. Confined Brownian ratchets could be used to control transport in mesostructures and to engineer new and more efficient devices for transport at the nanoscale.

Malgaretti, Paolo; Pagonabarraga, Ignacio; Rubi, J. Miguel

2013-05-01

80

Comments on experimental results of energy confinement of tokamak plasmas  

SciTech Connect

The results of energy-confinement experiments on steady-state tokamak plasmas are examined. For plasmas with auxiliary heating, an analysis based on the heat diffusion equation is used to define heat confinement time (the incremental energy confinement time). For ohmically sustained plasmas, experiments show that the onset of the saturation regime of energy confinement, marfeing, detachment, and disruption are marked by distinct values of the parameter /bar n//sub e///bar j/. The confinement results of the two types of experiments can be described by a single surface in 3-dimensional space spanned by the plasma energy, the heating power, and the plasma density: the incremental energy confinement time /tau//sub inc/ = ..delta..W/..delta..P is the correct concept for describing results of heat confinement in a heating experiment; the commonly used energy confinement time defined by /tau//sub E/ = W/P is not. A further examination shows that the change of edge parameters, as characterized by the change of the effective collision frequency ..nu../sub e/*, governs the change of confinement properties. The totality of the results of tokamak experiments on energy confinement appears to support a hypothesis that energy transport is determined by the preservation of the pressure gradient scale length. 70 refs., 6 figs., 1 tab.

Chu, T.K.

1989-04-01

81

Order, Disorder and Confinement  

SciTech Connect

Studying the order of the chiral transition for Nf = 2 is of fundamental importance to understand the mechanism of color confinement. We present results of a numerical investigation on the order of the transition by use of a novel strategy in finite size scaling analysis. The specific heat and a number of susceptibilities are compared with the possible critical behaviours. A second order transition in the O(4) and O(2) universality classes are excluded. Substantial evidence emerges for a first order transition. Results are in agreement with those found by studying the scaling properties of a disorder parameter related to the dual superconductivity mechanism of color confinement.

D'Elia, M. [Dipartimento di Fisica dell'Universita di Genova, Via Dodecaneso 33, I-16146 Genova (Italy); INFN, Sezione di Genova, Via Dodecaneso 33, I-16146 Genova (Italy); Di Giacomo, A.; Pica, C. [Dipartimento di Fisica dell'Universita di Pisa, largo Pontecorvo 3, I-56127 Pisa (Italy); INFN, Sezione di Pisa, largo Pontecorvo 3, I-56127 Pisa (Italy)

2006-01-12

82

Type-based confinement  

Microsoft Academic Search

Confinement properties impose a structure on object graphs which can be used to enforce encapsulation properties. From a practical point of view, encapsulation is essential for building secure object-oriented systems as security requires that the interface between trusted and untrusted components of a system be clearly delineated and restricted to the smallest possible set of operations and data structures. This

Tian Zhao; Jens Palsberg; Jan Vitek

2006-01-01

83

Confinement of quarks  

Microsoft Academic Search

A general introduction to the topological mechanism responsible for the absolute confinement of quarks inside hadronic bound states is given, including the effects of a finite instanton angle. We then propose a calculational technique for computing these states and their properties, where instead of topology we rely on a perturbative mechanism. It assumes that already before the topological mechanism can

Gerard't Hooft

2003-01-01

84

Materials self-assembly and fabrication in confined spaces  

SciTech Connect

Molecular assemblies have been mainly researched in open spaces for long time. However, recent researches have revealed that there are many interesting aspects remained in self-assemblies in confined spaces. Molecular association within nanospaces such as mesoporous materials provide unusual phenomena based on highly restricted molecular motions. Current research endeavors in materials science and technology are focused on developing either new class of materials or materials with novel/multiple functionalities which is often achived via molecular assembly in confined spaces. Template synthesis and guided assemblies are distinguishable examples for molecular assembly in confined spaces. So far, different aspects of molecular confinements are discussed separately. In this review, the focus is specifically to bring some potential developments in various aspects of confined spaces for molecular self-assembly under one roof. We arrange the sections in this review based on the nature of the confinements; accordingly the topological/geometrical confinements, chemical and biological confinements, and confinements within thin film, respectively. Following these sections, molecular confinements for practical applications are shortly described in order to show connections of these scientific aspects with possible practical uses. One of the most important facts is that the self-assembly in confined spaces stands at meeting points of top-down and bottom-up fabrications, which would be an ultimate key to push the limits of nanotechnology and nanoscience.

Ramanathan, Nathan Muruganathan [ORNL; Kilbey, II, S Michael [ORNL; Ji, Dr. Qingmin [National Institute for Materials Science, Tsukuba, Japan; Hill, Dr. Jonathan P [National Institute for Materials Science, Tsukuba, Japan; Ariga, Katsuhiko [National Institute for Materials Science, Tsukuba, Japan

2012-01-01

85

Dynamics and energetics of hydrophobically confined water  

NASA Astrophysics Data System (ADS)

The effects of water confined in regions between self-assembling entities is relevant to numerous contexts such as macromolecular association, protein folding, protein-ligand association, and nanomaterials self-assembly. Thus assessing the impact of confined water, and the ability of current modeling techniques to capture the salient features of confined water is important and timely. We present molecular dynamics simulation results investigating the effect of confined water on qualitative features of potentials of mean force describing the free energetics of self-assembly of large planar hydrophobic plates. We consider several common explicit water models including the TIP3P, TIP4P, SPC/E, TIP4P-FQ, and SWM4-NDP, the latter two being polarizable models. Examination of the free energies for filling and unfilling the volume confined between the two plates (both in the context of average number of confined water molecules and “depth” of occupancy) suggests TIP4P-FQ water molecules generally occupy the confined volume at separation distances larger than observed for other models under the same conditions. The connection between this tendency of TIP4P-FQ water and the lack of a pronounced barrier in the potential of mean force for plate-plate association in TIP4P-FQ water is explored by artificially, but systematically, populating the confined volume with TIP4P-FQ water at low plate-plate separation distances. When the critical separation distance [denoting the crossover from an unoccupied (dry) confined interior to a filled (wet) interior] for TIP4P-FQ is reduced by 0.5 Å using this approach, a barrier is observed; we rationalize this effect based on increased resistant forces introduced by confined water molecules at these low separations. We also consider the dynamics of water molecules in the confined region between the hydrophobes. We find that the TIP4P-FQ water model exhibits nonbulklike dynamics, with enhanced lateral diffusion relative to bulk. This is consistent with the reduced intermolecular water-water interaction indicated by a decreased molecular dipole moment in the interplate region. Analysis of velocity autocorrelation functions and associated power spectra indicate that the interplate region for TIP4P-FQ at a plate separation of 14.4 Å approaches characteristics of the pure water liquid-vapor interface. This is in stark contrast to the other water models (including the polarizable SWM4-NDP model).

Bauer, Brad A.; Ou, Shuching; Patel, Sandeep; Siva, Karthik

2012-05-01

86

Inertial Electrostatic Confinement (IEC) devices.  

National Technical Information Service (NTIS)

Inertial Electrostatic Confinement (IEC) is one of the earliest plasma confinement concepts, having first been suggested by P. T. Farnsworth in the 1950s. The concept involves a simple apparatus of concentric spherical electrostatic grids or a combination...

R. A. Nebel L. Turner T. N. Tiouririne D. C. Barnes W. D. Nystrom

1994-01-01

87

Electrostatic-Inertial Plasma Confinement.  

National Technical Information Service (NTIS)

The work was directed towards an answer to the question: 'How dense a plasma can be confined by electrostatic-inertial means.' Electrostatic-inertial plasma confinement consists of trapping charged particles in potential wells (of the electric field), whi...

T. J. Dolan J. T. Verdeyen B. E. Cherrington D. J. Meeker

1970-01-01

88

Totally confined explosive welding  

NASA Technical Reports Server (NTRS)

The undesirable by-products of explosive welding are confined and the association noise is reduced by the use of a simple enclosure into which the explosive is placed and in which the explosion occurs. An infrangible enclosure is removably attached to one of the members to be bonded at the point directly opposite the bond area. An explosive is completely confined within the enclosure at a point in close proximity to the member to be bonded and a detonating means is attached to the explosive. The balance of the enclosure, not occupied by explosive, is filled with a shaped material which directs the explosive pressure toward the bond area. A detonator adaptor controls the expansion of the enclosure by the explosive force so that the enclosure at no point experiences a discontinuity in expansion which causes rupture. The use of the technique is practical in the restricted area of a space station.

Bement, L. J. (inventor)

1978-01-01

89

Self-assembled morphologies of diblock copolymers confined in nanochannels: Effects of confinement geometry  

NASA Astrophysics Data System (ADS)

The self-assembly of diblock copolymers confined in channels of various shaped cross sections is studied using a simulated annealing technique with the ``single-site bond fluctuation'' model. In the bulk, the asymmetric diblock copolymers used in this study form hexagonally packed cylinders with period L0. The cross sections of the confining channels are of different shapes including regular triangles, rectangles, squares, regular hexagons, regular octagons, and ellipses. For a given geometry, the channel size (characterized by one or two lengths) is varied from very small to several times of L0. It is found that the geometry and size of the confining channels have a large effect on the structure and symmetry of the self-assembled morphologies. Multiple packed cylinders with the symmetry of the confining channels are the major morphologies for low-symmetry cross sections such as triangle, rectangle, and square. More complex structures such as helices or stacked toroids spontaneously form when the confining channels are shaped such as a regular hexagon, a regular octagon, or an ellipse. The domain spacing of the self-assembled structures can be altered by the shape and size of the confining channels. Our results are consistent with available experiments. These results indicate that the self-assembled structures of block copolymers can be manipulated by the shape of the confining channels.

Yu, Bin; Sun, Pingchuan; Chen, Tiehong; Jin, Qinghua; Ding, Datong; Li, Baohui; Shi, An-Chang

2007-05-01

90

Self-assembled morphologies of diblock copolymers confined in nanochannels: effects of confinement geometry.  

PubMed

The self-assembly of diblock copolymers confined in channels of various shaped cross sections is studied using a simulated annealing technique with the "single-site bond fluctuation" model. In the bulk, the asymmetric diblock copolymers used in this study form hexagonally packed cylinders with period L0. The cross sections of the confining channels are of different shapes including regular triangles, rectangles, squares, regular hexagons, regular octagons, and ellipses. For a given geometry, the channel size (characterized by one or two lengths) is varied from very small to several times of L0. It is found that the geometry and size of the confining channels have a large effect on the structure and symmetry of the self-assembled morphologies. Multiple packed cylinders with the symmetry of the confining channels are the major morphologies for low-symmetry cross sections such as triangle, rectangle, and square. More complex structures such as helices or stacked toroids spontaneously form when the confining channels are shaped such as a regular hexagon, a regular octagon, or an ellipse. The domain spacing of the self-assembled structures can be altered by the shape and size of the confining channels. Our results are consistent with available experiments. These results indicate that the self-assembled structures of block copolymers can be manipulated by the shape of the confining channels. PMID:17552796

Yu, Bin; Sun, Pingchuan; Chen, Tiehong; Jin, Qinghua; Ding, Datong; Li, Baohui; Shi, An-Chang

2007-05-28

91

Polymer translocation into a confined space: influence of the chain stiffness and the shape of the confinement.  

PubMed

Using two-dimensional Langevin dynamics simulations, we investigate the dynamics of polymer translocation into a confined space under a driving force through a nanopore, with particular emphasis on the chain stiffness and the shape of the confinement. We observe that with increasing the chain stiffness ?, the translocation time ? always increases for different shapes of confinements. For an ellipse, ? is different for the translocation through its minor and major axis directions. Under the weak confinement, the translocation through the minor axis direction is faster than that through the major axis direction for different ?, while this is true only for high ? under strong confinement. Particularly, for both weak and strong confinements we find that packaging into an ellipse through its minor axis direction is faster than that for a circle of the same area for high ?. These results are interpreted by the chain conformation during the translocation process and the time of an individual segment passing through the pore. PMID:24606377

Zhang, Kehong; Luo, Kaifu

2014-03-01

92

Inertial Confinement fusion targets  

NASA Technical Reports Server (NTRS)

Inertial confinement fusion (ICF) targets are made as simple flat discs, as hollow shells or as complicated multilayer structures. Many techniques were devised for producing the targets. Glass and metal shells are made by using drop and bubble techniques. Solid hydrogen shells are also produced by adapting old methods to the solution of modern problems. Some of these techniques, problems, and solutions are discussed. In addition, the applications of many of the techniques to fabrication of ICF targets is presented.

Hendricks, C. D.

1982-01-01

93

Topological confinement and superconductivity  

SciTech Connect

We derive a Kondo Lattice model with a correlated conduction band from a two-band Hubbard Hamiltonian. This mapping allows us to describe the emergence of a robust pairing mechanism in a model that only contains repulsive interactions. The mechanism is due to topological confinement and results from the interplay between antiferromagnetism and delocalization. By using Density-Matrix-Renormalization-Group (DMRG) we demonstrate that this mechanism leads to dominant superconducting correlations in aID-system.

Al-hassanieh, Dhaled A [Los Alamos National Laboratory; Batista, Cristian D [Los Alamos National Laboratory

2008-01-01

94

Energy confinement in Doublet III with high-Z limiters  

SciTech Connect

This report describes the experimental measurements and data analysis techniques used to evaluate the energy confinement in noncircular plasmas produced in Doublet III. Major aspects of the confinement measurements and analysis techniques are summarized. Machine parameters, diagnostic systems and discharge parameters relavent to the confinement measurements are given. Magnetic analysis techniques used to determine the plasma shape are reviewed. Scaling of the on-axis values of electron temperature, confinement time and Z/sub eff/ with plasma density is presented. Comparison with scaling results from other circular tokamaks is discussed. Numerical and analytic techniques developed for calculating the plasma energy confinement time and self-consistent profiles of density, temperature, current, and flux in non-circular geometries are described. These techniques are applied to the data and used to determine the central and global electron energy confinement time for a typical doublet plasma. Additional aspects of the confinement such as the radial dependence of the electron thermal conductivity and the estimated ion temperature are explored with the aid of a non-circular transport simulation code. The results of the confinement measurements are summarized and discussed. A brief summary of the theoretically expected effects of noncircularity on plasma confinement is included for reference as Appendix I.

Marcus, F.B.; Adcock, S.J.; Baker, D.R.; Blau, F.P.; Brooks, N.H.; Chase, R.P.; DeBoo, J.C.; Ejima, S.; Fairbanks, E.S.; Fisher, R.K.

1980-02-01

95

Confined Hard Disk Two Piston System Model  

NSDL National Science Digital Library

The Confined Hard Disk Two Piston System simulates a constant-energy two-dimensional system of unit mass particles confined by two frictionless pistons of equal mass M. This computer model complements theoretical work describing the adiabatic expansion of an ideal gas using the quasi-static approximation. Users can set the number of particles N, their diameter and their initial particle kinetic energy. Slow-moving particles are color-coded as blue and fast particles are color-coded as yellow. The time evolution of temperature, pressure, and piston speed are shown in a second window.   Particles in this model have unit mass and interact through contact forces. Collision times are computed analytically because particles and pistons move with constant velocity between collisions. The time evolution algorithm advances the particle position from collision to collision until the requested time step is achieved. The time evolution is then paused, data is accumulated, and the screen is redrawn. The Confined Hard Disk Two Piston System was developed using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_hd_ConfinedHardDiskTwoPistonSystem.jar file will run the program if Java is installed.

Christian, Wolfgang

2011-03-09

96

Molecular mixing via jets in confined volumes  

Microsoft Academic Search

A simple model is proposed to describe the molecular mixing characteristics of a two-dimensional turbulent jet that is discharged into a confined volume. The model, which is based on similarity and physical considerations of only the large-scale motions, derives the characteristic time for the problem and identifies the regime for which the mixing will be most rapid. Results are reported

R. E. Breidenthal; V. R. Buonadonna; M. F. Weisbach

1990-01-01

97

Static current profile control and RFP confinement  

NASA Astrophysics Data System (ADS)

Static current profile control (CPC) is shown numerically to substantially enhance plasma confinement in the reversed-field pinch (RFP). By suitable application of an auxiliary electric field and adjustment of its internal location, width and amplitude, strongly decreased levels of dynamo fluctuations are obtained. The simulations are performed using a fully non-linear, resistive magnetohydrodynamic model, including the effects of ohmic heating as well as parallel and perpendicular heat conduction along stochastic field lines. The importance of controlling the parallel current profile in the core plasma to minimize the effects of tearing modes on confinement is thus confirmed. A near three-fold increase in energy confinement is found and poloidal plasma beta increases by 30% from 0.20 to 0.27. The edge heat flux is reduced to a third of that of the conventional RFP. The high-confinement phase is interrupted here by a crash, characterized by a rapid decrease in confinement. A detailed study of the crash phase is carried out by the standard ?? theory and a fully resistive linearized time-spectral method; the generalized weighted residual method. The analysis suggests that the instability is caused by pressure-driven, resistive g-modes. Inclusion of anisotropic thermal conduction reduces the linear growth rates. As compared with our earlier numerical studies of CPC in the RFP, employing feedback control, the present static control scheme should be more easily implemented experimentally.

Scheffel, Jan; Schnack, Dalton D.; Mirza, Ahmed A.

2013-11-01

98

Confinement Contains Condensates  

SciTech Connect

Dynamical chiral symmetry breaking and its connection to the generation of hadron masses has historically been viewed as a vacuum phenomenon. We argue that confinement makes such a position untenable. If quark-hadron duality is a reality in QCD, then condensates, those quantities that have commonly been viewed as constant empirical mass-scales that fill all spacetime, are instead wholly contained within hadrons; i.e., they are a property of hadrons themselves and expressed, e.g., in their Bethe-Salpeter or light-front wave functions. We explain that this paradigm is consistent with empirical evidence, and incidentally expose misconceptions in a recent Comment.

Brodsky, Stanley J.; Roberts, Craig D.; Shrock, Robert; Tandy, Peter C.

2012-03-12

99

Physics of Improved Core Confinement with Lithium Injection in TFTR  

Microsoft Academic Search

Lithium pellet injection and laser ablation of lithium produced dramatically improved ion thermal, toroidal momentum, and particle confinement in very high temperature TFTR supershot plasmas. Attained continously through a gradual reduction of the edge particle influx from the plasma facing surfaces, the supershot regime is characterized by an energy confinement time strongly and inversely correlated with edge particle influx. Lithium

D. R. Ernst

2000-01-01

100

Turbulence and energy confinement in TORE SUPRA Ohmic discharges  

Microsoft Academic Search

Results on confinement and turbulence from a set of Ohmic discharges in TORE SUPRA are discussed. Attention is focused on the saturation of the energy confinement time and it is emphasized that this saturation can be explained by a saturation of the electron heat diffusivity. The ion behaviour is indeed governed by dilution and equipartition effects. Although the ion heat

X. Garbet; J. Payan; C. Laviron; P. Devynck; S. K. Saha; H. Capes; X. P. Chen; J. P. Coulon; C. Gil; G. R. Harris; T. Hutter; A.-L. Pecquet; A. Truc; P. Hennequin; F. Gervais; A. Quemeneur

1992-01-01

101

Polymer chain dynamics under nanoscopic confinements.  

PubMed

It is shown that the confinement of polymer melts in nanopores leads to chain dynamics dramatically different from bulk behavior. This so-called corset effect occurs both above and below the critical molecular mass and induces the dynamic features predicted for reptation. A spinodal demixing technique was employed for the preparation of linear poly(ethylene oxide) (PEO) confined to nanoscopic strands that are in turn embedded in a quasi-solid and impenetrable methacrylate matrix. Both the molecular weight of the PEO and the mean diameter of the strands were varied to a certain degree. The chain dynamics of the PEO in the molten state was examined with the aid of field-gradient NMR diffusometry (time scale, 10(-2)-10(0) s) and field-cycling NMR relaxometry (time scale, 10(-9)-10(-4) s). The dominating mechanism for translational displacements probed in the nanoscopic strands by either technique is shown to be reptation. On the time scale of spin-lattice relaxation time measurements, the frequency dependence signature of reptation (i.e., T1 approximately nu(3/4)) showed up in all samples. A "tube" diameter of only 0.6 nm was concluded to be effective on this time scale even when the strand diameter was larger than the radius of gyration of the PEO random coils. This corset effect is traced back to the lack of the local fluctuation capacity of the free volume in nanoscopic confinements. The confinement dimension is estimated at which the crossover from confined to bulk chain dynamics is expected. PMID:15833611

Kimmich, Rainer; Fatkullin, Nail; Mattea, Carlos; Fischer, Elmar

2005-02-01

102

Confined placental mosaicism.  

PubMed Central

In most pregnancies the chromosomal complement detected in the fetus is also present in the placenta. The detection of an identical chromosomal complement in both the fetus and its placenta has always been expected as both develop from the same zygote. However, in approximately 2% of viable pregnancies studied by chorionic villus sampling (CVS) at 9 to 11 weeks of gestation, the cytogenetic abnormality, most often trisomy, is confined to the placenta. This phenomenon is known as confined placental mosaicism (CPM). It was first described by Kalousek and Dill in term placentas of infants born with unexplained intrauterine growth restriction (IUGR). Contrary to generalised mosaicism, which is characterised by the presence of two or more karyotypically different cell lines within both the fetus and its placenta, CPM represents tissue specific chromosomal mosaicism affecting the placenta only. The diagnosis of CPM is most commonly made when, after the diagnosis of chromosomal mosaicism in a CVS sample, the second prenatal testing (amniotic fluid culture or fetal blood culture analysis) shows a normal diploid karyotype.

Kalousek, D K; Vekemans, M

1996-01-01

103

Instantons confined by monopole strings  

NASA Astrophysics Data System (ADS)

It is known that monopoles can be confined by vortex strings in d=3+1 while vortices can be confined by domain lines in d=2+1. Here, as a higher dimensional generalization of these, we show that Yang-Mills instantons can be confined by monopole strings in d=4+1. We achieve this by putting the system into the Higgs phase in which the configuration can be constructed inside a non-Abelian vortex sheet.

Nitta, Muneto

2013-03-01

104

Magnetic confinement fusion energy research  

Microsoft Academic Search

Controlled thermonuclear fusion offered a relatively clean energy solution with completely inexhaustible fuel and unlimited power capacity. The scientific and technological problem consisted in magnetically confining a hot, dense plasma for an appreciable fraction of a second. The scientific and mathematical problem was to describe the behavior, such as confinement, stability, flow, compression, heating, energy transfer and diffusion of this

H. Grad

1977-01-01

105

Inertial Electrostatic Confinement (IEC) devices  

Microsoft Academic Search

Inertial Electrostatic Confinement (IEC) is one of the earliest plasma confinement concepts, having first been suggested by P. T. Farnsworth in the 1950's. The concept involves a simple apparatus of concentric spherical electrostatic grids or a combination of grids and magnetic fields. An electrostatic structure is formed from the confluence of electron or ion beams. Gridded IEC systems have demonstrated

R. A. Nebel; L. Turner; T. N. Tiouririne; D. C. Barnes; W. D. Nystrom; R. W. Bussard; G. H. Miley; J. Javedani; Y. Yamamoto

1994-01-01

106

BRS Transformation and Color Confinement.  

National Technical Information Service (NTIS)

The condition of confinement of quarks and gluons in QCD is derived. It is shown that color confinement is realized when there exist massles scalar color-octet bound states of two Faddeev-Popov ghosts. (ERA citation 08:008561)

K. Nishijima

1982-01-01

107

Direct Observation of Confined Single Chain Dynamics by Neutron Scattering  

NASA Astrophysics Data System (ADS)

Neutron spin echo has revealed the single chain dynamic structure factor of entangled polymer chains confined in cylindrical nanopores with chain dimensions either much larger or smaller than the lateral pore sizes. In both situations, a slowing down of the dynamics with respect to the bulk behavior is only observed at intermediate times. The results at long times provide a direct microscopic measurement of the entanglement distance under confinement. They constitute the first experimental microscopic evidence of the dilution of the total entanglement density in a polymer melt under strong confinement, a phenomenon that so far was hypothesized on the basis of various macroscopic observations.

Martín, J.; Krutyeva, M.; Monkenbusch, M.; Arbe, A.; Allgaier, J.; Radulescu, A.; Falus, P.; Maiz, J.; Mijangos, C.; Colmenero, J.; Richter, D.

2010-05-01

108

Confining ensemble of dyons  

SciTech Connect

We construct the integration measure over the moduli space of an arbitrary number of N kinds of dyons of the pure SU(N) gauge theory at finite temperatures. The ensemble of dyons governed by the measure is mathematically described by a (supersymmetric) quantum field theory that is exactly solvable and is remarkable for a number of striking features: (i) The free energy has the minimum corresponding to the zero average Polyakov line, as expected in the confining phase; (ii) the correlation function of two Polyakov lines exhibits a linear potential between static quarks in any N-ality nonzero representation, with a calculable string tension roughly independent of temperature; (iii) the average spatial Wilson loop falls off exponentially with its area and the same string tension; (iv) at a critical temperature, the ensemble of dyons rearranges and deconfines; and (v) the estimated ratio of the critical temperature to the square root of the string tension is in excellent agreement with the lattice data.

Diakonov, Dmitri; Petrov, Victor [St. Petersburg NPI, Gatchina, 188 300, St. Petersburg (Russian Federation)

2007-09-01

109

Localization dynamics of fluids in random confinement.  

PubMed

The dynamics of two-dimensional fluids confined within a random matrix of obstacles is investigated using both colloidal model experiments and molecular dynamics simulations. By varying fluid and matrix area fractions in the experiment, we find delocalized tracer particle dynamics at small matrix area fractions and localized motion of the tracers at high matrix area fractions. In the delocalized region, the dynamics is subdiffusive at intermediate times, and diffusive at long times, while in the localized regime, trapping in finite pockets of the matrix is observed. These observations are found to agree with the simulation of an ideal gas confined in a weakly correlated matrix. Our results show that Lorentz gas systems with soft interactions are exhibiting a smoothening of the critical dynamics and consequently a rounded delocalization-to-localization transition. PMID:24093304

Skinner, Thomas O E; Schnyder, Simon K; Aarts, Dirk G A L; Horbach, Jürgen; Dullens, Roel P A

2013-09-20

110

ITER L-Mode Confinement Database  

SciTech Connect

This paper describes the content of an L-mode database that has been compiled with data from Alcator C-Mod, ASDEX, DIII, DIII-D, FTU, JET, JFT-2M, JT-60, PBX-M, PDX, T-10, TEXTOR, TFTR, and Tore-Supra. The database consists of a total of 2938 entries, 1881 of which are in the L-phase while 922 are ohmically heated (OH) only. Each entry contains up to 95 descriptive parameters, including global and kinetic information, machine conditioning, and configuration. The paper presents a description of the database and the variables contained therein, and it also presents global and thermal scalings along with predictions for ITER. The L-mode thermal confinement time scaling was determined from a subset of 1312 entries for which the thermal confinement time scaling was provided.

S.M. Kaye and the ITER Confinement Database Working Group

1997-10-01

111

Confinement scaling and ignition in tokamaks  

SciTech Connect

A drift wave turbulence model is used to compute the scaling and magnitude of central electron temperature and confinement time of tokamak plasmas. The results are in accord with experiment. Application to ignition experiments shows that high density (1 to 2) . 10/sup 15/ cm/sup -3/, high field, B/sub T/ > 10 T, but low temperature T approx. 6 keV constitute the optimum path to ignition.

Perkins, F.W.; Sun, Y.C.

1985-10-01

112

Partial confinement photonic crystal waveguides  

SciTech Connect

One-dimensional photonic crystal waveguides with an incomplete photonic band gap are modeled and proposed for an integration application that exploits their property of partial angular confinement. Planar apodized photonic crystal structures are deposited by plasma enhanced chemical vapor deposition and characterized by reflectivity as a function of angle and polarization, validating a partial confinement design for light at 850 nm wavelength. Partial confinement identifies an approach for tailoring waveguide properties by the exploitation of conformal film deposition over a substrate with angularly dependent topology. An application for an optoelectronic transceiver is demonstrated.

Saini, S.; Hong, C.-Y.; Pfaff, N.; Kimerling, L. C.; Michel, J. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2008-12-29

113

Magnetic Confinement Fusion Energy Research.  

National Technical Information Service (NTIS)

Controlled Thermonuclear Fusion offers probably the only relatively clean energy solution with completely inexhaustible fuel and unlimited power capacity. The scientific and technological problem consists in magnetically confining a hot, dense plasma (pre...

H. Grad

1977-01-01

114

Layering transition in confined silicon.  

PubMed

The structure of quasi-2D liquid silicon confined to slit nanopores has been investigated using molecular dynamics (MD) simulations. An obvious structural change from a low-density low-coordinated liquid to a high-density highly coordinated liquid has been found in the confined silicon with the increase of the slit size. This kind of structural transition results from layering in the confined silicon, which disappears with the increase of temperature. In the process of layering transition, the coordination distribution of quasi-2D liquid undergoes an evolutionary process from the initial non-uniform distribution to the final uniform distribution. In addition, our results also indicate that the increase of pressure will also induce a layering transition in the confined silicon. PMID:24609530

He, Yezeng; Li, Xiongying; Li, Hui; Jiang, Yanyan; Bian, Xiufang

2014-04-21

115

Ionic liquids in confined geometries.  

PubMed

Over recent years the Surface Force Apparatus (SFA) has been used to carry out model experiments revealing structural and dynamic properties of ionic liquids confined to thin films. Understanding characteristics such as confinement induced ion layering and lubrication is of primary importance to many applications of ionic liquids, from energy devices to nanoparticle dispersion. This Perspective surveys and compares SFA results from several laboratories as well as simulations and other model experiments. A coherent picture is beginning to emerge of ionic liquids as nano-structured in pores and thin films, and possessing complex dynamic properties. The article covers structure, dynamics, and colloidal forces in confined ionic liquids; ionic liquids are revealed as a class of liquids with unique and useful confinement properties and pertinent future directions of research are highlighted. PMID:22301770

Perkin, Susan

2012-04-21

116

Dissipation-Driven Behavior of Nonpropagating Hydrodynamic Solitons Under Confinement  

NASA Astrophysics Data System (ADS)

We have identified a physical mechanism that rules the confinement of nonpropagating hydrodynamic solitons. We show that thin boundary layers arising on walls are responsible for a jump in the local damping. The outcome is a weak dissipation-driven repulsion that determines decisively the solitons' long-time behavior. Numerical simulations of our model are consistent with experiments. Our results uncover how confinement can generate a localized distribution of dissipation in out-of-equilibrium systems. Moreover, they show the preponderance of such a subtle effect in the behavior of localized structures. The reported results should explain the dynamic behavior of other confined dissipative systems.

Gordillo, Leonardo; García-Áustes, Mónica A.

2014-04-01

117

Dissipation-driven behavior of nonpropagating hydrodynamic solitons under confinement.  

PubMed

We have identified a physical mechanism that rules the confinement of nonpropagating hydrodynamic solitons. We show that thin boundary layers arising on walls are responsible for a jump in the local damping. The outcome is a weak dissipation-driven repulsion that determines decisively the solitons' long-time behavior. Numerical simulations of our model are consistent with experiments. Our results uncover how confinement can generate a localized distribution of dissipation in out-of-equilibrium systems. Moreover, they show the preponderance of such a subtle effect in the behavior of localized structures. The reported results should explain the dynamic behavior of other confined dissipative systems. PMID:24815651

Gordillo, Leonardo; García-Ñustes, Mónica A

2014-04-25

118

A geometric realization of confinement  

Microsoft Academic Search

We study the geometric realization of the Higgs phenomenon in type II string compactification on Calabi-Yau manifolds. The string description is most directly phrased in terms of confinement of magnetic flux, with magnetic charged states arising from D-branes wrapped around chains as opposed to cycles. The rest of the closed cycle of the D-brane world-volume is manifested as a confining

Brian R. Greene; David R. Morrison; Cumrun Vafa

1996-01-01

119

A geometric realization of confinement  

Microsoft Academic Search

We study the geometric realization of the Higgs phenomenon in type II string compactifications on Calabi-Yau manifolds. The string description is most directly phrased in terms of confinement of magnetic flux, with magnetic charged states arising from D-branes wrapped around chains as opposed to cycles. The rest of the closed cycle of the D-brane world-volume is manifested as a confining

Brian R. Greene; David R. Morrison; Cumrun Vafa

1996-01-01

120

2XIIB plasma confinement experiments  

Microsoft Academic Search

The paper discusses results of plasma confinement experiments in the 2XIIB magnetic mirror device. Experiments attempting to achieve field-reversal using neutral-beam injection in which the central magnetic field is reduced by 90% but field lines are not closed are reported. Experiments with different neutral-beam aiming show that at constant beta both electron temperature and the energy-confinement parameter increase at larger

T. C. Simonen; J. F. Clauser; F. H. Coensgen; D. L. Correll; W. F. Cummins; J. H. Foote; A. H. Futch; R. K. Goodman; D. P. Grubb; R. P. Drake

1979-01-01

121

Alternative approaches to plasma confinement  

NASA Technical Reports Server (NTRS)

The potential applications of fusion reactors, the desirable properties of reactors intended for various applications, and the limitations of the Tokamak concept are discussed. The principles and characteristics of 20 distinct alternative confinement concepts are described, each of which may be an alternative to the Tokamak. The devices are classed as Tokamak-like, stellarator-like, mirror machines, bumpy tori, electrostatically assisted, migma concept, and wall-confined plasma.

Roth, J. R.

1977-01-01

122

Heterogeneous catalysis and confinement effects  

Microsoft Academic Search

The aim of this study is to highlight the impact of confinement effects in catalysis for reactants confined in small mesopores. Double bond isomerization of 1-hexene at 343K has been chosen as model reaction and mesostructured aluminosilicates of the MCM-41 type with the very same chemical composition (Si\\/Al=400±20) and varying pore sizes (2.3–9.3nm) were used as catalysts. Adsorption isotherms of

Stéphane Pariente; Philippe Trens; François Fajula; Francesco Di Renzo; Nathalie Tanchoux

2006-01-01

123

Solvent cavitation under solvophobic confinement  

NASA Astrophysics Data System (ADS)

The stability of liquids under solvophobic confinement can tip in favor of the vapor phase, nucleating a liquid-to-vapor phase transition that induces attractive forces between confining surfaces. In the case of water adjacent to hydrophobic surfaces, experimental and theoretical evidence support confinement-mediated evaporation stabilization of biomolecular and colloidal assemblies. The macroscopic thermodynamic theory of cavitation under confinement establishes the connection between the size of the confining surfaces, interfacial free energies, and bulk solvent pressure with the critical evaporation separation and interfacial forces. While molecular simulations have confirmed the broad theoretical trends, a quantitative comparison based on independent measurements of the interfacial free energies and liquid-vapor coexistence properties has, to the best of our knowledge, not yet been performed. To overcome the challenges of simulating a large number of systems to validate scaling predictions for a three-dimensional fluid, we simulate both the forces and liquid-vapor coexistence properties of a two-dimensional Lennard-Jones fluid confined between solvophobic plates over a range of plate sizes and reservoir pressures. Our simulations quantitatively agree with theoretical predictions for solvent-mediated forces and critical evaporation separations once the length dependence of the solvation free energy of an individual confining plate is taken into account. The effective solid-liquid line tension length dependence results from molecular scale correlations for solvating microscopic plates and asymptotically decays to the macroscopic value for plates longer than 150 solvent diameters. The success of the macroscopic thermodynamic theory at describing two-dimensional liquids suggests application to surfactant monolayers to experimentally confirm confinement-mediated cavitation.

Ashbaugh, Henry S.

2013-08-01

124

Incommensurability of a confined system under shear.  

PubMed

We study a chain of harmonically interacting atoms confined between two sinusoidal substrate potentials, when the top substrate is driven through an attached spring with a constant velocity. This system is characterized by three inherent length scales and closely related to physical situations with confined lubricant films. We show that, contrary to the standard Frenkel-Kontorova model, the most favorable sliding regime is achieved by choosing chain-substrate incommensurabilities belonging to the class of cubic irrational numbers (e.g., the spiral mean). At large chain stiffness, the well known golden mean incommensurability reveals a very regular time-periodic dynamics with always higher kinetic friction values with respect to the spiral mean case. PMID:16090702

Braun, O M; Vanossi, A; Tosatti, E

2005-07-01

125

Confined PBX 9501 gap reinitiation studies  

SciTech Connect

For explosive systems that exhibit gaps or cracks between their internal components (either by design or mechanical failure), measurable time delays exist for detonation waves crossing them. Reinitiation across such gaps is dependent on the type of explosive, gap width, gap morphology, confinement, and temperature effects. To examine this reinitiation effect, a series of tests has been conducted to measure the time delay across a prescribed gap within an 'infinitely' confined PBX 9501 system. Detonation breakout along the explosive surface is measured with a streak camera, and flow features are examined during reinitiation near the gap. Such tests allow for quantitative determination of the time delay corresponding to the time of initiation across a given gap oriented normal to the direction of the detonation wave. Measured time delays can be compared with numerical calculations, making it possible to validate initiation models as well as estimate detonation run-up distances. Understanding this reinitiation behavior is beneficial for the design and evaluation of explosive systems that require precision timing and performance.

Salyer, Terry R [Los Alamos National Laboratory; Hill, Larry G [Los Alamos National Laboratory; Lam, Kin [Los Alamos National Laboratory

2009-01-01

126

Electron confinement in an annular Penning trap  

NASA Astrophysics Data System (ADS)

Electron confinement in an annular version of a Malmberg-Penning trap [S. Robertson and B. Walch, Rev. Sci. Instrum. 70, 2993 (1999)] has been investigated for conditions in which mobility is the dominant source of transport. A non-neutral plasma of electrons is contained in the annular region between coaxial cylinders. An axial magnetic field provides radial confinement and electric bias potentials provide axial confinement. The electric field that drives transport is determined primarily by the potential difference applied to the cylinders. The measured density decay rates have the expected dependence upon electric field, collision frequency and magnetic field and are within a factor of 2 of calculated values. Experiments are performed with an axial field of 5-18 mT, a radial electric field of 11-38 V/cm, a helium pressure of 0.01-0.13 mTorr, an initial electron density of ~106 cm-3, and the density decay times are 1-10 ms.

Robertson, Scott; Walch, Bob

2000-06-01

127

Locomotion Control of Caenorhabditis elegans through Confinement  

PubMed Central

The model organism Caenorhabditis elegans shows two distinct locomotion patterns in laboratory situations: it swims in low viscosity liquids and it crawls on the surface of an agar gel. This provides a unique opportunity to discern the respective roles of mechanosensation (perception and proprioception) and mechanics in the regulation of locomotion and in the gait selection. Using an original device, we present what to our knowledge are new experiments where the confinement of a worm between a glass plate and a soft agar gel is controlled while recording the worm's motion. We observed that the worm continuously varied its locomotion characteristics from free swimming to slow crawling with increasing confinement so that it was not possible to discriminate between two distinct intrinsic gaits. This unicity of the gait is also proved by the fact that wild-type worms immediately adapted their motion when the imposed confinement was changed with time. We then studied locomotory deficient mutants that also exhibited one single gait and showed that the light touch response was needed for the undulation propagation and that the ciliated sensory neurons participated in the joint selection of motion period and undulation-wave velocity. Our results reveal that the control of maximum curvature, at a sensory or mechanical level, is a key ingredient of the locomotion regulation.

Lebois, Felix; Sauvage, Pascal; Py, Charlotte; Cardoso, Olivier; Ladoux, Benoit; Hersen, Pascal; Di Meglio, Jean-Marc

2012-01-01

128

Plasma confinement studies in open systems  

NASA Astrophysics Data System (ADS)

Studies in open systems in the world are reviewed from viewpoints of the potential confinement and magnetohydrodynamic (MHD) stability. The tandem mirror GAMMA 10 has shown the potential confinement of a high-ion-temperature plasma from an analysis of the time evolution of end-loss ion current and end-loss ion energy distributions. The central cell density was increased by 50% by the potential confinement. In the HIEI tandem mirror H-mode-like phenomena were observed with an increase in density and diamagnetic signal in a limiter biasing experiment. Potential formation phenomena in plasmas are studied by 0741-3335/41/3A/024/img1-like Upgrade under different magnetic field configurations and plasma conditions. The fully axisymmetric tandem mirror AMBAL-M is under construction and its end mirror system has been assembled. Heating experiments of a plasma gun produced plasma by neutral beam injection and ICRF heating are in progress. The gas dynamic trap (GDT) experiment has successfully produced an MHD-stable high-temperature, high-density plasma. In GOL-3-II, a high-density plasma with several 100 eV temperature is created by powerful relativistic electron beam injection. Construction of HANBIT has been completed and experiments on plasma production and ICRF heating have begun.

Yatsu, Kiyoshi

1999-03-01

129

Status of global energy confinement studies  

SciTech Connect

Empirical scaling expressions, reflecting the parametric dependence of the L-mode energy confinement time, have been used not only as benchmarks for tokamak operation and theories of energy transport, but for predicting the performance of proposed tokamak devices. Several scaling expressions based on data from small-and medium-sized devices have done well in predicting performance in larger devices, although great uncertainty exists in extrapolating yet farther, into the ignition regime. Several approaches exist for developing higher confidence scaling expressions. These include reducing the statistical uncertainty by identifying and filling in gaps in the present database, making use of more sophisticated statistical techniques, and developing scalings for confinement regimes within which future devices will operate. Confidence in the scaling expressions will be increased still if the expressions can be more directly tied to transport physics theory. This can be done through the use of dimensionless parameters, better describing the edge and core confinement regimes separately, and by incorporating transport models directly into the scaling expressions. 50 refs., 5 figs., 3 tabs.

Kaye, S.M.; Bell, M.G. (Princeton Univ., NJ (USA). Plasma Physics Lab.); Barnes, C.W. (Los Alamos National Lab., NM (USA)); DeBoo, J.C.; Waltz, R. (General Atomics Co., San Diego, CA (USA)); Greenwald, M.; Sigmar, D. (Massachusetts Inst. of Tech., Cambridge, MA (USA). Plasma Fusion Center); Riedel, K. (New York Univ., NY (USA). Courant Inst. of Mathematical Sciences); Uckan, N. (Oak Ridge National L

1990-02-01

130

Inertial-confinement fusion  

Microsoft Academic Search

Reports that larger drivers, projected for the near future, are expected to compress the deuterium-tritium fuel to 1000 times its liquid density and achieve ignition of the fuel pellet. Vast amounts of fusion energy are released from the sun (and other stars) by natural thermonuclear processes that fuse atoms of lighter elements into atoms of heavier elements. In comparison to

J. H. Pitts; J. Hovingh; S. Walters

1982-01-01

131

Vortex Fusion and Giant Vortex States in Confined Superconducting Condensates  

NASA Astrophysics Data System (ADS)

In a direct scanning tunneling spectroscopy experiment we address the problem of the quantum vortex phases in strongly confined superconductors. The strong confinement regime is achieved in in situ grown ultrathin single nanocrystals of Pb by tuning their lateral size to a few coherence lengths. Upon an external magnetic field, the scanning tunneling spectroscopy revealed novel ultradense arrangements of single Abrikosov vortices characterized by an intervortex distance up to 3 times shorter than the bulk critical one. At yet stronger confinement we discovered the giant vortex phase; the spatial evolution of the excitation tunneling spectra in the cores of these unusual quantum objects was explored. We anticipate the giant vortex phase to be a common feature of other confined quantum condensates such as superfluids, Bose-Einstein condensates of cold atoms, etc.

Cren, T.; Serrier-Garcia, L.; Debontridder, F.; Roditchev, D.

2011-08-01

132

Achieving Long Confinement in a Toroidal Electron Plasma  

NASA Astrophysics Data System (ADS)

We observe the m = 1 diocotron mode in a partial toroidal trap, and use it as the primary diagnostic for observing the plasma confinement. The frequency of the m = 1 mode, which is approximately proportional to the trapped charge, decays on a three second timescale. The confinement time exceeds, by at least an order of magnitude, the confinement observed in all other toroidal traps for non-neutral plasmas and approaches the theoretical limit set by magnetic pumping transport. Numerical simulations that include toroidal effects are employed to accurately extract plasma charge, equilibrium position and m = 1 mode amplitude from the experimental data. Future work will include attempts to withdraw the electron source in order to study confinement in a full torus.

Marler, J. P.; Smoniewski, J.; Ha, Bao; Stoneking, M. R.

2009-03-01

133

Achieving Long Confinement in a Toroidal Electron Plasma  

SciTech Connect

We observe the m = 1 diocotron mode in a partial toroidal trap, and use it as the primary diagnostic for observing the plasma confinement. The frequency of the m = 1 mode, which is approximately proportional to the trapped charge, decays on a three second timescale. The confinement time exceeds, by at least an order of magnitude, the confinement observed in all other toroidal traps for non-neutral plasmas and approaches the theoretical limit set by magnetic pumping transport. Numerical simulations that include toroidal effects are employed to accurately extract plasma charge, equilibrium position and m = 1 mode amplitude from the experimental data. Future work will include attempts to withdraw the electron source in order to study confinement in a full torus.

Marler, J. P.; Smoniewski, J.; Ha Bao; Stoneking, M. R. [Lawrence University, Appleton, WI, 54911 (United States)

2009-03-30

134

Vortex fusion and giant vortex states in confined superconducting condensates.  

PubMed

In a direct scanning tunneling spectroscopy experiment we address the problem of the quantum vortex phases in strongly confined superconductors. The strong confinement regime is achieved in in situ grown ultrathin single nanocrystals of Pb by tuning their lateral size to a few coherence lengths. Upon an external magnetic field, the scanning tunneling spectroscopy revealed novel ultradense arrangements of single Abrikosov vortices characterized by an intervortex distance up to 3 times shorter than the bulk critical one. At yet stronger confinement we discovered the giant vortex phase; the spatial evolution of the excitation tunneling spectra in the cores of these unusual quantum objects was explored. We anticipate the giant vortex phase to be a common feature of other confined quantum condensates such as superfluids, Bose-Einstein condensates of cold atoms, etc. PMID:21929264

Cren, T; Serrier-Garcia, L; Debontridder, F; Roditchev, D

2011-08-26

135

Time  

ERIC Educational Resources Information Center

When a teacher gives their time to a student, it is more significant to that student than anything else one could do for him or her. Music teachers deal with time all the time. Someone once said that "time is like money: we never have enough." This may seem true; however, time is not like money. One can make more money, but one cannot "make time."…

Circle, David

2005-01-01

136

Hydrodynamics of Confined Active Fluids  

NASA Astrophysics Data System (ADS)

We theoretically describe the dynamics of swimmer populations in rigidly confined thin liquid films. We first demonstrate that hydrodynamic interactions between confined swimmers depend solely on their shape and are independent of their specific swimming mechanism. We also show that, due to friction with the nearby rigid walls, confined swimmers do not just reorient in flow gradients but also in uniform flows. We then quantify the consequences of these microscopic interaction rules on the large-scale hydrodynamics of isotropic populations. We investigate in detail their stability and the resulting phase behavior, highlighting the differences with conventional active, three-dimensional suspensions. Two classes of polar swimmers are distinguished depending on their geometrical polarity. The first class gives rise to coherent directed motion at all scales, whereas for the second class we predict the spontaneous formation of coherent clusters (swarms).

Brotto, Tommaso; Caussin, Jean-Baptiste; Lauga, Eric; Bartolo, Denis

2013-01-01

137

Velocity alignment leads to high persistence in confined cells  

NASA Astrophysics Data System (ADS)

Many cell types display random motility on two-dimensional substrates but crawl persistently in a single direction when confined in a microchannel or on an adhesive micropattern. Does this imply that the motility mechanism of confined cells is fundamentally different from that of unconfined cells? We argue that both free- and confined-cell migration may be described by a generic model of cells as "velocity-aligning" active Brownian particles previously proposed to solve a completely separate problem in collective cell migration. Our model can be mapped to a diffusive escape over a barrier and analytically solved to determine the cell's orientation distribution and repolarization rate. In quasi-one-dimensional confinement, velocity-aligning cells maintain their direction for times that can be exponentially larger than their persistence time in the absence of confinement. Our results suggest an important connection between single- and collective-cell migration: high persistence in confined cells corresponds with fast alignment of velocity to cell-cell forces.

Camley, Brian A.; Rappel, Wouter-Jan

2014-06-01

138

Confinement and edge currents  

SciTech Connect

The tokamak fusion experimental results provide strong evidence that electrons flow out of an OH-heated plasma along the outer edge of the tokamak's major radius (Rmax), through the vacuum-chamber structure, and back into the plasma at the inner surface (Rmin). There are many results that support this flow of current. The four primary supporting facts are: (1) the voltage measurements on outer limiters, such as the movable limiter on TFTR; (2) the bias limiter experiments; (3) the observation of ionized light (called MARFEs) on the inner radius; (4) the thermal-disruption times and forces produced are in accordance with calculations based on the edge circuit cross-current concept. The thermal-decay time and the forces are not satisfactorily explained without a cross current. This paper provides an engineering explanation of how this edge cross current can exist and how its driving force is generated.

Murray, J.G.

1989-03-01

139

Electrohydrodynamics of DNA in confinement  

NASA Astrophysics Data System (ADS)

New methods of DNA sequencing aim to exploit the direct reading of individual DNA molecules. Such methods require one be able to elongate DNA molecules so that individual base-pairs may be accessed. In turn, this requires a detailed understanding of the mechanical and thermodynamic behavior of DNA, so that external manipulation and confinement successfully stretch the molecule. We aim to study the interplay between electrostatic and hydrodynamic interactions on the conformations of coarse-grained DNA through use of computer simulations with the general geometry Ewald-like method (GGEM), both in bulk and under geometric confinement.

Whitmer, Jonathan K.; Hernandez-Ortiz, Juan P.; de Pablo, Juan J.

2012-02-01

140

Confinement and heating studies of field-reversed configurations  

SciTech Connect

Confinement studies of field-reversed configurations (FRCs) have been actively pursued during the past ten years with the larger and longer-lived FRCs produced in the FRX-C and FRX-C/LSM devices. Confinement measurements have included the global FRC quantities and, in some cases, profiles of electron temperature and density. The inferred confinement times and transport coefficients are used for comparison with transport models as wells as to find the best operating conditions in the experiment. Global power flow modelling shows that energy confinement during the equilibrium phase is usually dominated by particle losses, with a substantial secondary contribution from electron thermal conduction. Particle losses in present kinetic FRCs are strongly influenced by open field line confinement, which complicates the study of transport mechanisms. The electron thermal conduction is observed to be anomalous, as in other plasma devices. The bulk electrical resistivity is also anomalous and shows no evidence of classical Spitzer scaling. Recently, the resistive anomaly has been shown to correlate with tilt-like magnetic perturbations observed with Mirnov coils. FRC confinement studies have also been extended to a higher temperature regime during magnetic compression heating. In these experiments, translated FRCs are compressed by increasing the external magnetic flux up to a factor of seven on a time scale between the radial Alfven time and the FRC lifetime. Electron and ion temperatures up to 0.4 keV and 1.6 keV, respectively have been obtained. Confinement times scale roughly as r{sup 2} during compression.

Chrien, R.E.

1990-01-01

141

Confinement regime transitions in ASDEX  

Microsoft Academic Search

The authors give an overview of the different confinement regimes observed on ASDEX and compare the changes during the transition phases with qualitative tendencies suggested by theoretical models. The transitions discussed are those between purely Ohmic heating and additional heating in the L-regime between the L- and the H-regime and between discharges with flat and peaked electron density profiles.

K. Lackner; O. Gruber; F. Wagner; G. Becker; M. Bessenrodt-Weberpals; B. Bomba; H.-S. Bosch; H. Bruhns; R. Buchse; A. Carlson; G. Dodel; A. Eberhagen; H.-U. Fahrbach; G. Fussmann; O. Gehre; J. Gernhardt; L. Giannone; S. von Goeler; K. Grassie; G. Haas; H. Herrmann; J. Hofmann; E. Holzhauer; K. Hubner; G. Janeschitz; A. Kallenbach; F. Karger; M. Kaufmann; O. Kluber; M. Kornherr; K. Krieger; J. Kucinski; R. Lang; G. Lisitano; H. M. Mayer; K. McCormick; D. Meisel; V. Mertens; E. R. Muller; H. D. Murmann; J. Neuhauser; H. Niedermeyer; R. Nolte; J. M. Noterdaeme; W. Poschenrieder; L. B. Ran; D. E. Roberts; H. Rohr; J. Roth; A. Rudyj; F. Ryter; W. Sandmann; F. Schneider; U. Schneider; W. Schneider; G. Siller; E. Speth; F. X. Soldner; A. Stabler; K. H. Steuer; U. Stroth; J. Szigeti; E. Taglauer; N. Tsois; H. Verbeek; O. Vollmer; R. Wunderlich; H. Wurz; H. R. Yang; H. Zohm

1989-01-01

142

Inertial confinement fusion (ICF) review  

SciTech Connect

During its 1996 winter study JASON reviewed the DOE Inertial Confinement Fusion (ICF) program. This included the National Ignition Facility (NIF) and proposed studies. The result of the review was to comment on the role of the ICF program in support of the DOE Science Based Stockpile Stewardship program.

Hammer, D.; Dyson, F.; Fortson, N.; Novick, B.; Panofsky, W.; Rosenbluth, M.; Treiman, S.; York, H.

1996-03-01

143

Flex Circuitry for Confined Spaces  

NASA Technical Reports Server (NTRS)

To facilitate installation of electronic equipment in confined spaces, circuitry preassembled on flexible wiring. Mother boards, large bypass capacitors, and interface connectors mounted on flexible wiring and tested before installation. Flexible circuits eliminate need for in-place hardwiring and allow smaller enclosures to be used.

Fitzpatrick, J. B.; Maier, L. C.

1986-01-01

144

Classical energy confinement in Alcator  

Microsoft Academic Search

Nearly classical behaviour, from the viewpoint of energy confinement, is observed in the Alcator tokamak. A study of the energy balance of the central core of the plasma has been carried out in the regime 1014 cm-3 <=n¯e <= 6 × 1014 cm-3, 130 kA <= IP <= 160 kA and BT = 6 T. At the higheet densities the

A. Gondhalekar; D. Overskei; R. R. Parker

1979-01-01

145

Limiting Spectra from Confining Potentials.  

ERIC Educational Resources Information Center

The author explains that, for confining potentials and large quantum numbers, the bound-state energies rise more rapidly as a function of n the more rapidly the potential rises with distance. However, the spectrum can rise no faster than n squared in the nonrelativistic case, or n in the relativistic case. (Author/GA)

Nieto, Michael Martin; Simmons, L. M., Jr.

1979-01-01

146

String theory and quark confinement  

Microsoft Academic Search

This article is based on a talk given at the “Strings '97” conference. It discusses the search for the universality class of confining strings. The key ingredients include the loop equations, the zigzag symmetry, the non-linear renormalization group. Some new tests for the equivalence between gauge fields and strings are proposed.

Alexandre M. Polyakov

1998-01-01

147

PREFACE: Water in confined geometries  

Microsoft Academic Search

The study of water confined in complex systems in solid or gel phases and\\/or in contact with macromolecules is relevant to many important processes ranging from industrial applications such as catalysis and soil chemistry, to biological processes such as protein folding or ionic transport in membranes. Thermodynamics, phase behaviour and the molecular mobility of water have been observed to change

Mauro Rovere

2004-01-01

148

Kinetics of Diffusing Polymer Encounter in Confined Cellular Microdomains  

NASA Astrophysics Data System (ADS)

We study the mean first time that two monomers, located on the same polymer, encounter in a confined microdomain. Approximating the confined geometry by a harmonic potential well, we obtain an asymptotic expression for the mean first encounter time (MFETC) as a function of the radius ? around one monomer. By studying the end-to-end distance of the polymer in a ball using the Edwards' formalism, we derive an other estimation of the MFETC. We validate the asymptotic formulas using Brownian simulations and derive their range of validity in terms of the polymer length. We apply the present models to compute the mean time for a gene located far away from a promoter site to be activated during looping in confined genomic territories.

Amitai, A.; Kupka, I.; Holcman, D.

2013-12-01

149

Millisecond burning of confined energetic materials during cookoff  

Microsoft Academic Search

The response of a system containing an energetic material (EM) to an abnormal thermal environment is termed cookoff. To predict the violence of reaction of confined energetic materials during cookoff requires a description of the relevant physical processes that occur on time scales Ranging from days to submicroseconds. The time-to-ignition can be characterized accurately using heat transfer with chemistry and

R. G. Schmitt; T. A. Baer

1997-01-01

150

Response of marine bacterioplankton to differential filtration and confinement.  

PubMed Central

The bacterioplankton community of confined seawater at 25 degrees C changed significantly within 16 h of collection. Confinement increased CFU, total cell number (by epifluorescence microscopy), and average cell volume of bacterioplankton and increased the turnover rate of amino acids in seawater sampled at Frying Pan Shoals, N.C. The bacterioplankton community was characterized by two components: differential doubling times during confinement shifted dominance from bacteria which were nonculturable to bacteria which were culturable on a complex nutrient medium. Culturable cells (especially those of the genera Pseudomonas, Alcaligenes, and Acinetobacter) increased from 0.08% of the total cell number in the seawater immediately after collection to 13% at 16 h and 41% at 32 h of confinement. Differential filtration before confinement indicated that particles passing through a 3.9-microns-, but retained by a 0.2-micron-, pore-size Nuclepore filter may be a major source of primary amines to the confined population. The 3.0-microns filtration increased growth rate and ultimate numbers of culturable cells through the removal of bacterial predators or the release of primary amines from cells damaged during filtration or both.

Ferguson, R L; Buckley, E N; Palumbo, A V

1984-01-01

151

Membrane Cholesterol Strongly Influences Confined Diffusion of Prestin  

PubMed Central

Prestin is the membrane motor protein that drives outer hair cell (OHC) electromotility, a process that is essential for mammalian hearing. Prestin function is sensitive to membrane cholesterol levels, and numerous studies have suggested that prestin localizes in cholesterol-rich membrane microdomains. Previously, fluorescence recovery after photobleaching experiments were performed in HEK cells expressing prestin-GFP after cholesterol manipulations, and revealed evidence of transient confinement. To further characterize this apparent confined diffusion of prestin, we conjugated prestin to a photostable fluorophore (tetramethylrhodamine) and performed single-molecule fluorescence microscopy. Using single-particle tracking, we determined the microscopic diffusion coefficient from the full time course of the mean-squared deviation. Our results indicate that prestin undergoes diffusion in confinement regions, and that depletion of membrane cholesterol increases confinement size and decreases confinement strength. By interpreting the data in terms of a mathematical model of hop-diffusion, we quantified these cholesterol-induced changes in membrane organization. A complementary analysis of the distribution of squared displacements confirmed that cholesterol depletion reduces prestin confinement. These findings support the hypothesis that prestin function is intimately linked to membrane organization, and further promote a regulatory role for cholesterol in OHC and auditory function.

Kamar, R.I.; Organ-Darling, L.E.; Raphael, R.M.

2012-01-01

152

Monte Carlo simulation of plasma confinement in mirror and cusp fields  

Microsoft Academic Search

Plasma confinement times for mirror and cusp devices are investigated by using a Monte Carlo simulation model which can include the effects of binary collisions, arbitrary spatial change in the magnetic field, and external electric fields. For a mirror, the simulation results are in good agreement with theory. For a cusp (without an external electric field), the confinement time is

Y. Ohsawa; T. Kamimura

1979-01-01

153

Physics of magnetic confinement fusion  

NASA Astrophysics Data System (ADS)

Fusion is the energy source of the universe. The local conditions in the core of the Sun allow the transfer of mass into energy, which is finally released in the form of radiation. Technical fusion melts deuterons and tritons to helium releasing large amounts of energy per fusion process. Because of the conditions for fusion, which will be deduced, the fusion fuel is in the plasma state. Here we report on the confinement of fusion plasmas by magnetic fields. Different confinement concepts — tokamaks and stellarators — will be introduced and described. The first fusion reactor, ITER, and the most modern stellarator, Wendelstein 7-X, are under construction. Their basic features and objectives will be presented.

Wagner, F.

2013-06-01

154

Inertial-confinement-fusion targets  

SciTech Connect

Inertial confinement fusion (ICF) targets are made as simple flat discs, as hollow shells or as complicated multilayer structures. Many techniques have been devised for producing the targets. Glass and metal shells are made by using drop and bubble techniques. Solid hydrogen shells are also produced by adapting old methods to the solution of modern problems. Some of these techniques, problems and solutions are discussed. In addition, the applications of many of the techniques to fabrication of ICF targets is presented.

Hendricks, C.D.

1981-11-16

155

Feynman amplitudes with confinement included  

SciTech Connect

Amplitudes for any multipoint Feynman diagram are written taking into account vacuum background confining field. Higher order gluon exchanges are treated within background perturbation theory. For amplitudes with hadrons in initial or final states vertices are shown to be expressed by the corresponding wave function with the renormalized z factors. Examples of two-point functions, three-point functions (form factors), and decay amplitudes are explicitly considered.

Simonov, Yu. A. [Institute of Theoretical and Experimental Physics (Russian Federation)

2009-07-15

156

Two flavor QCD and confinement  

Microsoft Academic Search

We argue that the order of the chiral transition for Nf=2 is a sensitive probe of the QCD vacuum, in particular, of the mechanism of color confinement. A strategy is developed to investigate the order of the transition by use of finite size scaling analysis. An in-depth numerical investigation is performed with staggered fermions on lattices with Lt=4 and Ls=12,

Massimo D'Elia; Adriano di Giacomo; Claudio Pica

2005-01-01

157

Ion beam inertial confinement target  

DOEpatents

A target for implosion by ion beams composed of a spherical shell of frozen DT surrounded by a low-density, low-Z pusher shell seeded with high-Z material, and a high-density tamper shell. The target has various applications in the inertial confinement technology. For certain applications, if desired, a low-density absorber shell may be positioned intermediate the pusher and tamper shells.

Bangerter, Roger O. (Danville, CA); Meeker, Donald J. (Livermore, CA)

1985-01-01

158

Gluon Confinement and Quantum Censorship  

NASA Astrophysics Data System (ADS)

The dynamical Maxwell-cut, a degeneracy is shown to be a precursor of condensate in the ?4 and the sine-Gordon models. The difference of the way the Maxwell-cut is obtained is pointed out and quantum censorship, the generation of semiclassically looking phenomenon by loop-corrections is conjectured in the sine-Gordon model. It is argued that quantum censorship and gluon confinement exclude each other.

Polónyi, János

2011-04-01

159

Neutron Assay System for Confinement Vessel Disposition  

Microsoft Academic Search

Los Alamos National Laboratory has a number of spherical confinement vessels (CVs) remaining from tests involving nuclear materials. These vessels have an inner diameter of 6 feet with 1-inch thick steel walls. The goal of the Confinement Vessel Disposition (CVD) project is to remove debris and reduce contamination inside the CVs. The Confinement Vessel Assay System (CVAS) was developed to

Katherine C. Frame; Mark M. Bourne; William J. Crooks; Louise Evans; Douglas R. Mayo; David K. Miko; William R. Salazar; Sy Stange; Jose I. Valdez; Georgiana M. Vigil

2012-01-01

160

Initial deuterium confinement studies in DIII-D tokamak  

SciTech Connect

The operational space of DIII-D has been extended to include high current, high power deuterium neutral beam heating of deuterium discharges in both the single null and double null configurations. Recent completion of the neutron shielding of the DIII-D facility has allowed operation in these new parameter regimes while maintaining a low neutron dose at the site boundary. The plasma current and neutral beam power ranges with D{degree} {yields} D{sup +} operation have been extended to P{sub T} {le} 12 MW and I{sub p} {le} 2.5 MA. Comparison of H-mode discharges in pure H with those in pure D indicates a continuing superior confinement in deuterium for values of q {ge} 3; however at lower values of q the confinement becomes similar. Analysis of the energy confinement in this regime has shown no major differences in current or power scaling compared to H{degree} {yields} D{sup +} operation. Energy confinement during the ELMing phase of D{degree} {yields} D{sup +} H-mode discharges scales linearly with the plasma current and deteriorates with neutral beam power. Recent, ongoing time dependent analysis of discharges with long ELM-free periods following the L to H transition indicate that the energy confinement time may be independent of power so that power degradation may be a manifestation of ELMs. 1 ref., 5 figs.

DeBoo, J.C.; Schissel, D.P.; Burrell, K.; St. John, H.

1989-08-01

161

Hydrodynamic modes in a confined granular fluid.  

PubMed

Confined granular fluids, placed in a shallow box that is vibrated vertically, can achieve homogeneous stationary states due to energy injection mechanisms that take place throughout the system. These states can be stable even at high densities and inelasticities allowing for a detailed analysis of the hydrodynamic modes that govern the dynamics of granular fluids. By analyzing the decay of the time correlation functions it is shown that there is a crossover from a quasielastic regime in which energy evolves as a slow mode to an inelastic regime with energy slaved to the other conserved fields. The two regimes have well differentiated transport properties and in the inelastic regime the dynamics can be described by a reduced hydrodynamics with modified longitudinal viscosity and sound speed. The crossover between the two regimes takes place at a wave vector that is proportional to the inelasticity. A two-dimensional granular model, with collisions that mimic the energy transfers that take place in a confined system, is studied by means of microscopic simulations. The results show excellent agreement with the theoretical framework and allow validation of hydrodynamiclike models. PMID:23496507

Brito, Ricardo; Risso, Dino; Soto, Rodrigo

2013-02-01

162

Properties of non-neutral electron plasmas confined with a magnetic mirror field  

SciTech Connect

A low energy non-neutral electron plasma was confined with a magnetic mirror field and an electrostatic potential to investigate the basic confinement properties of a simple magnetic mirror trap. The mirror ratio of the magnetic field was increased up to 5. As expected the confinement time became longer as a function of the mirror ratio. The axially integrated radial density profiles in equilibrium were measured and compared with a theoretical model. The axial electrostatic oscillations of a confined electron plasma were also observed.

Higaki, H.; Ito, K.; Saiki, W.; Omori, Y.; Okamoto, H. [Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima, 739-8530 (Japan)

2007-06-15

163

Psychosocial Accommodation to Group Confinement in the Advanced Base Habitat.  

National Technical Information Service (NTIS)

There are many military situations in which small groups of individuals must live and function in confining environments for extended periods of time. The U.S. Air Force, through its contractor Hamilton Standard, has developed a model for an Advanced Base...

P. H. Warren

1988-01-01

164

JETTO simulations of Te/Ti effects on plasma confinement  

NASA Astrophysics Data System (ADS)

A series of hot-electron plasmas were produced at JET with the aim of clarifying the dependence of the energy confinement time on the electron to ion temperature ratio, Te/Ti. Although these plasmas showed a clear increase in the ion heat diffusivity with higher Te/Ti, their energy confinement time remained constant. In this paper we propose that these observations are consistent with the predictions of the Weiland model of energy transport. A feedback loop amplifying the ion diffusivity simultaneously flattens the ion temperature profile, and keeps the ion heat flux constant. The electron transport shows no dependence on Te/Ti, and hence there is no scaling of the confinement time with the temperature ratio. To support these claims we show a series of numerical simulations using the Weiland model. For scaling law purposes it is also interesting to note that the energy confinement time does not show any dependence on the effective input power ratio, Pe/Pi, either.

Asp, E.; Weiland, J.; Garbet, X.; Mantica, P.; Parail, V.; Suttrop, W.; EFDA-JET contributors, the

2005-03-01

165

Sufficient conditions for identifying transmissivity in a confined aquifer  

Microsoft Academic Search

It has been known for some time that the transmissivity T in a confined, steady-state aquifer ? can be uniquely determined in the neighbourhood of sources and sinks even if Cauchy data on the characteristics are lacking. Recently Chicone and Gerlach extended this result to those regions of the aquifer that are not completely crossed by a characteristic line. In

C R Dietrich; G N Newsam

1990-01-01

166

Preliminary studies of inertial-electrostatic confinement fusion experiments  

Microsoft Academic Search

Preliminary inertial-electrostatic confinement fusion experiments have been carried out using hydrogen gas, and measurements of the light from a plasma core were made. The life time of charged particles in gridded IECF configuration is found to be longer than in the conventional spherical electrode discharges. The light intensity is found to be proportional to about 2\\/3 power of the input

Yasushi Yamamoto; Masami Ohnishi; Kiyoshi Yoshikawa; Hisayuki Toku; Mitsunori Hasegawa; Takashi Matsuo

1996-01-01

167

Observation of Avalanchelike Phenomena in a Magnetically Confined Plasma  

SciTech Connect

Electron temperature fluctuations seen in a magnetically confined tokamak plasma have some of the characteristics of the avalanchelike events sometimes associated with self-organized criticality, including intermittency, large space and time scales, ''1/f '' spectra, large tails in the autocorrelation function, and clear evidence of radial propagation. (c) 2000 The American Physical Society.

Politzer, P. A.

2000-02-07

168

Strong light confinement in a photonic amorphous diamond structure  

NASA Astrophysics Data System (ADS)

Formation of cavity modes in a recently found unique photonic structure ``photonic amorphous diamond (PAD)'' has been investigated by finite-difference time domain calculations. A well-confined monopole mode has been found to form when a rod is removed from the structure. The quality (Q) factor and mode volume (Vm) of such a cavity mode in PAD have been evaluated and compared with those in a conventional photonic crystal with a crystalline diamond structure. The two structures have shown nealy the same Q-factor and Vm, leading to the conclusion that strong light confinement is realizable in PAD as well as conventional photonic crystals.

Imagawa, Shigeki; Edagawa, Keiichi; Notomi, Masaya

2012-04-01

169

Dynamics of Director Fluctuations in Confined and Filled Liquid Crystals.  

NASA Astrophysics Data System (ADS)

Dynamic light scattering was applied to study the influence of randomness as well of boundary conditions (planar-axial and homeotropic-radial) and layer thickness (at nanoscale) of 5CB and 8CB confined to random porous matrices, to cylindrical pores and filled with Aerosil particles (hydrophilic and hydrophobic) on phase transitions and relaxation of director orientational fluctuations. For confined 8CB in the nematic phase two well-defined relaxation processes were for confined liquid crystals. The first process is associated with bulk-like nematic director fluctuations. The second relaxation process (with relaxation time slower than the first one) is most likely due to the fluctuations in layers nearest the wall surface. We found that for homeotropic boundary conditions of confined liquid crystal, the pore wall-liquid crystal interactions influence on the properties of the surface layer is stronger than in the case of axial orientation, particularly, and the influence of boundary conditions on N-Sm-A phase transition in confined 8CB is stronger than on isotropic- nematic phase transition. The separation between the first and the second (slow) process is clearer for thinner layers and the amplitude of slow process is greater for thinner layers. This suggests that the slow process is surface related relaxation. This relaxation was observed in filled liquid crystals as well.

Arroyo, Edwin; Basu, Sarmistha; Aliev, Fouad

2006-03-01

170

Issues in tokamak/stellarator transport and confinement enhancement mechanisms  

SciTech Connect

At present, the mechanism for anomalous energy transport in low-{beta} toroidal plasmas -- tokamaks and stellarators -- remains unclear, although transport by turbulent E {times} B velocities associated with nonlinear, fine-scale microinstabilities is a leading candidate. This article discusses basic theoretical concepts of various transport and confinement enhancement mechanisms as well as experimental ramifications which would enable one to distinguish among them and hence identify a dominant transport mechanism. While many of the predictions of fine-scale turbulence are born out by experiment, notable contradictions exist. Projections of ignition margin rest both on the scaling properties of the confinement mechanism and on the criteria for entering enhanced confinement regimes. At present, the greatest uncertainties lie with the basis for scaling confinement enhancement criteria. A series of questions, to be answered by new experimental/theoretical work, is posed to resolve these outstanding contradictions (or refute the fine-scale turbulence model) and to establish confinement enhancement criteria. 73 refs., 4 figs., 5 tabs.

Perkins, F.W.

1990-08-01

171

Ingestive Behavior of Lambs Confined in Individual and Group Stalls  

PubMed Central

The experiment was conducted to evaluate the ingestive behavior of lambs confined in individual and group stalls. We used thirty-four lambs in their growing phase, aged an average of three months, with mean initial live weight of 17.8±5.2 kg. They were allotted in a completely randomized design with 24 animals kept in individual stalls and 10 animals confined as a group. The experiment lasted for a total of 74 days, and the first 14 days were dedicated to the animals’ adaption to the management, facilities and diets. The data collection period lasted 60 days, divided into three 20-d periods for the behavior evaluation. The animals were subjected to five days of visual observation during the experiment period, by the quantification of 24 h a day, with evaluations on the 15th day of each period and an interim evaluation consisting of two consecutive days on the 30th and 31st day of the experiment. The animals confined as a group consumed less (p<0.05) fiber. However, the animals confined individually spent less (p<0.05) time on feeding, rumination and chewing activities and longer in idleness. Therefore, the lower capacity of lambs confined in groups to select their food negatively affects their feeding behavior.

Filho, A. Eustaquio; Carvalho, G. G. P.; Pires, A. J. V.; Silva, R. R.; Santos, P. E. F.; Murta, R. M.; Pereira, F. M.

2014-01-01

172

IR spectroscopy of water vapor confined in nanoporous silica aerogel.  

PubMed

The absorption spectrum of the water vapor, confined in the nanoporous silica aerogel, was measured within 5000-5600 cm(-1) with the IFS 125 HR Fourier spectrometer. It has been shown, that tight confinement of the molecules by the nanoporous size leads to the strong lines broadening and shift. For water vapor lines, the HWHM of confined molecules are on the average 23 times larger than those for free molecules. The shift values are in the range from -0.03 cm(-1) to 0.09 cm(-1). Some spectral lines have negative shift. The data on the half-widths and center shifts for some strongest H(2)O lines have been presented. PMID:21164954

Ponomarev, Yu N; Petrova, T M; Solodov, A M; Solodov, A A

2010-12-01

173

Hot Electron Confinement in High Intensity Laser-Matter Interactions  

NASA Astrophysics Data System (ADS)

High-intensity (>10^18 W/cm^2) lasers can produce relativistic electrons (˜MeV) when focused onto solid density targets. We present measurements of escaped relativistic electron lifetimes in short pulse laser-irradiated solid experiments. Electron durations measured were significantly longer than the laser pulse length, suggesting the presence of phenomena which confine high energy electrons within the target-plasma volume. Investigating the confinement time of high energy electrons exceeds the limits of any simple plasma expansion models. Utilizing the implicit hybrid particle-in-cell code LSP [D. R. Welch et al., Phys. Plasmas 13, 063105 (2006)], experimental conditions were simulated to explore the physics of hot electron confinement in laser-irradiated materials. *This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Elberson, Lee; Ping, Yuan; Shepherd, Ronnie; Wilks, Scott; MacKinnon, Andrew; Patel, Prav; Hill, Wendell

2010-11-01

174

Inertial Confinement Fusion in a Z-? Pinch  

NASA Astrophysics Data System (ADS)

The implosion of a dense ? pinch plasma driven by an annular Z-pinch is considered. A cryogenic fiber is coaxially located within an annular gas jet Z-pinch. The imploding Z-pinch traps an applied axial magnetic field and conserves flux. The axial magnetic field increases due to compression of the outer pinch and attains values in excess of tens of megagauss with field risetimes of order, dB/dt = 10MG/ns, with an order of magnitude shorter rise time than the Z-pinch current. An azimuthal ?-current is induced on the fiber surface with a similar rise time; which could not otherwise be achieved in a simple fiber Z-pinch due to the large inductance initially presented by the small diameter axial plasma. The implosion transfers Z-pinch kinetic energy to the magnetic field and then to the ?-pinch. The final plasma pressure of the ?- pinch exceeds the magnetic pressure so that the ?-pinch then expands-the only confinement is inertial. To reach break-even and beyond, with reasonable Z-pinch currents, we increase the radiative losses by seeding the discharge with high Z impurities. Seeding a cryogenic Hydrogen-like fiber with high Z-impurities would substantially reduce the preheat in the ?-pinch, over a non-seeded discharge, and increase the final density by radiative collapse. Thus n? ~ 1014 cm-3 -s could be reached with a confinement time of 0.01 ns and density of 1025 cm-3 predicted in this paper.

Rahman, H. U.; Ney, P.; Wessel, F. J.; Rostoker, N.

1994-03-01

175

Compact inertial confinement multireactor concepts  

SciTech Connect

Inertial confinement fusion (ICF) commercial-applications plant-optimum driver pulse repetition rates may exceed reactor pulse-repetition-rate capabilities. Thus, more than one reactor may be required for low-cost production of electric power, process heat, fissionable fuels, etc., in ICF plants. Substantial savings in expensive reactor containment cells and blankets can be realized by placing more than one reactor in a cell and by surrounding more than one reactor cavity with a single blanket system. There are also some potential disadvantages associated with close coupling in compact multicavity blankets and multireactor cells. Tradeoffs associated with several scenarios have been studied.

Pendergrass, J.H.

1985-01-01

176

Cauchy flights in confining potentials  

NASA Astrophysics Data System (ADS)

We analyze confining mechanisms for Lévy flights evolving under an influence of external potentials. Given a stationary probability density function (pdf), we address the reverse engineering problem: design a jump-type stochastic process whose target pdf (eventually asymptotic) equals the preselected one. To this end, dynamically distinct jump-type processes can be employed. We demonstrate that one “targeted stochasticity” scenario involves Langevin systems with a symmetric stable noise. Another derives from the Lévy-Schrödinger semigroup dynamics (closely linked with topologically induced super-diffusions), which has no standard Langevin representation. For computational and visualization purposes, the Cauchy driver is employed to exemplify our considerations.

Garbaczewski, Piotr

2010-03-01

177

1.3 micron multiquantum well decoupled confinement heterostructure (MQW-DCH) laser diodes  

Microsoft Academic Search

A 1.3 micron multiquantum well decoupled confinement heterostructure (MQW-DCH) laser diode has been developed. This novel laser structure introduces internal barriers between the active quantum wells and the optical waveguide. It is thus possible to have, at the same time, deep quantum wells to prevent carrier leakage and a strong optical waveguide with a high confinement factor. The barrier parameters

S. Hausser; H. P. Meier; R. Germann; Ch. S. Harder

1993-01-01

178

Confined fission track lengths in apatite: a diagnostic tool for thermal history analysis  

Microsoft Academic Search

Fission-track ages in apatite are generally accepted as giving a measure of the time over which a sample has been exposed to temperatures below approximately 100° C. A compilation of the lengths of confined fission tracks in a wide variety of apatites from different geological environments has shown that the distribution of confined track lengths can provide unique thermal history

A. J. W. Gleadow; I. R. Duddy; P. F. Green; J. F. Lovering

1986-01-01

179

Monte Carlo simulation of plasma confinement in mirror and cusp fields  

Microsoft Academic Search

Plasma confinement times for mirror and cusp devices are investigated by using a newly developed Monte Carlo simulation model which can include the effects of binary collisions, arbitrary spatial change in the magnetic field, and external electric fields. For a mirror, the simulation results are in good agreement with theory. For a cusp (without an external electric field) the confinement

Yukiharu Ohsawa; Tetsuo Kamimura

1980-01-01

180

Confinement and Mayer cluster expansions  

NASA Astrophysics Data System (ADS)

In this paper, we study a class of grand-canonical partition functions with a kernel depending on a small parameter ?. This class is directly relevant to Nekrasov partition functions of 𝒩 = 2 SUSY gauge theories on the 4d ?-background, for which ? is identified with one of the equivariant deformation parameter. In the Nekrasov-Shatashvili limit ??0, we show that the free energy is given by an on-shell effective action. The equations of motion take the form of a TBA equation. The free energy is identified with the Yang-Yang functional of the corresponding system of Bethe roots. We further study the associated canonical model that takes the form of a generalized matrix model. Confinement of the eigenvalues by the short-range potential is observed. In the limit where this confining potential becomes weak, the collective field theory formulation is recovered. Finally, we discuss the connection with the alternative expression of instanton partition functions as sums over Young tableaux.

Bourgine, Jean-Emile

2014-05-01

181

Confining standing waves in optical corrals.  

PubMed

Near-field scanning optical microscopy images of solid wall, circular, and elliptical microscale corrals show standing wave patterns confined inside the structures with a wavelength close to that of the incident light. The patterns inside the corrals can be tuned by changing the size and material of the walls, the wavelength of incident light, and polarization direction for elliptical corrals. Finite-difference time-domain calculations of the corral structures agree with the experimental observations and reveal that the electric and magnetic field intensities are out of phase inside the corral. A theoretical modal analysis indicates that the fields inside the corrals can be attributed to p- and s-polarized waveguide modes, and that the superposition of the propagating and evanescent modes can explain the phase differences between the fields. These experimental and theoretical results demonstrate that electromagnetic fields on a dielectric surface can be controlled in a predictable manner. PMID:19243190

Babayan, Yelizaveta; McMahon, Jeffrey M; Li, Shuzhou; Gray, Stephen K; Schatz, George C; Odom, Teri W

2009-03-24

182

Heating, Confinement, and Extrapolation to Reactors  

SciTech Connect

The total amount of heating power coupled to the plasma P{sub tot} and the energy confinement time are determining parameters for realizing the plasma conditions suitable for the reactor. We recall that the ignition condition can be expressed by the following condition on the triple fusion product:NT{tau} = P{sub tot}{tau}{sup 2}/(3 Vol) = 3N{sup 2}T{sup 2}Vol/P{sub tot} > (NT{tau}){sub ignition} (1)with T [approximately equal to] 15 keV where {tau} = E/P{sub tot} is the energy confinement time, E = 3NT Vol for an isothermal plasma with T{sub i} = T{sub e} = T and a plasma volume Vol; N is the plasma density. The value T [approximately equal to] 15 keV corresponds to the minimum value of (NT{tau}){sub ignition} as a function T (see Fig. 1). In the present discussion for the sake of simplicity, we neglect density and temperature profile factors. The heating power in most of the present experiments is given by P{sub tot} = P{sub OH} + P{sub add} where P{sub OH} is the ohmic power and P{sub add} is the additional heating due to neutral beam injection or R.F. heating. At ignition, the additional heating power must come completely from the energetic {alpha} particles produced by the fusion reactions and we must have P{sub tot} = P{sub {alpha}} if we neglect the residual P{sub OH} and the plasma losses by Bremsstrahlung (P{sub Br} [is proportional to] N{sup 2} T{sup 1/2})

Ongena, J.; Messiaen, A.M

2004-03-15

183

Energy and particle confinement in ITER (International Thermonuclear Experimental Reactor)  

SciTech Connect

ITER will require a level of energy ({tau}{sub E}) and particle ({tau}{sub p}) confinement sufficient for reaching ignition and extended burn of DT plasmas, with steady-state, high-Q (Q = P{sub fusion}/P{sub aux} = 5P{sub {alpha}}/P{sub aux}) operation as an ultimate goal. This translates into a required confinement capability of T{sub i}(0)n{sub DT}(0){tau}{sub E} {approximately}4--8 {times} 10{sup 21} keV{center dot}s/m{sup 3} for Q {approximately}5--{infinity} (where T{sub i}(0) is the central ion temperature, n{sub DT}(0) is the central DT fuel ion density, {tau}{sub E} is the global energy confinement time). In addition, {tau}{sub p} {sup He}/{tau}{sub E} < 10 is required to ensure that the thermal {alpha}-particle (He) accumulation (n{sub He}/n{sub e}) is less than 10% (where {tau}{sub p}{sup He} is the global thermal alpha particle containment time). Furthermore, the tritium fuel burnup fraction under nominal burn conditions must be greater than 1.5%. While the ITER Tn{tau}{sub E} requirement is about ten times the highest value achieved in JET (3), the extrapolation in plasma physics parameters is less. If {beta} (ratio of plasma kinetic pressure to magnetic pressure), {nu}* (collisionality), and {rho}/a (ratio of the ion gyroradius to the plasma minor radius) are taken as the relevant dimensionless parameters to characterize the plasma, the extrapolation from present JET performance to ITER is a factor {le}2. The ITER concept is based on the expectation that H-mode confinement can be achieved for long pulse. This paper covers the energy and particle confinement issues for ITER. 15 refs.

Uckan, N.A. (Oak Ridge National Lab., TN (USA)); Yushmanov, P.N.; Mukhovatov, V.S.; Parail, V.V.; Putvinskii, S. (Gosudarstvennyj Komitet po Ispol'zovaniyu Atomnoj Ehnergii SSSR, Moscow (USSR). Inst. Atomnoj Ehnergii); Takizuka, T.; Tsunematsu, T.; Yoshino, R. (Japan Atomic Energy Research Inst., Tokyo (Japan)); Borrass, K.; Engelmann, F.; Kardaun, O.; Lackner, K. (Max-Planck-Institut fuer Plasmaphysik,

1990-01-01

184

Dielectric Relaxation in Confined Ferroelectric Polymer  

Microsoft Academic Search

The dynamics of segmental and chain motions in poly(vinylidene fluoride) confined to anodized aluminum oxide nanopores by melt-wetting was studied by broad-band dielectric spectroscopy. Molecular structure of the confined polymer was studied by means of wide-angle X-ray scattering in the transmission mode with ? scanning. The confined polymer was found to form multilayered cylindrical mesostructure containing three polymorphs with the

Bo?ena Hilczer; Ewa Markiewicz; Katarzyna Pogorzelec-Glaser; Maria Po?omska; Adam Pietraszko

2011-01-01

185

Holographic Schwinger effect in confining phase  

NASA Astrophysics Data System (ADS)

We consider the Schwinger effect in confining phase by using a holographic setup. The potential analysis is performed for the confining D3-brane and D4-brane back-grounds. We find the critical electric field above which there is no potential barrier and the system becomes unstable catastrophically. An intriguing point is that no Schwinger effect occurs when the electric field is smaller than the confining string tension.

Sato, Yoshiki; Yoshida, Kentaroh

2013-09-01

186

Confined Lennard-Jones Two Piston System Model  

NSDL National Science Digital Library

The Confined Lennard-Jones Two Piston System simulates a constant-energy two-dimensional system of particles confined by two frictionless pistons of equal mass M. This computer model complements theoretical work describing the adiabatic expansion of an ideal gas using the quasi-static approximation. Users can set the initial particle kinetic energy, Lennard Jones parameters, and the initial particle separation. Slow-moving particles are color-coded as blue and fast particles are color-coded as yellow. The time evolution of temperature, pressure, and piston speed are shown in a second window. Particles in this model have unit mass and interact through pairwise Lennard-Jones forces and hard-wall contact forces. The instantaneous temperature is computed using the average particle kinetic energy and the pressure is computed using the virial expansion. The Confined Lennard-Jones Two Piston System is a supplemental simulation for the article "Evolution of ideal gas mixtures confined in an insulated container by two identical pistons" by Joaquim Anacleto, Joaquim Alberto C. Anacleto, and J. M. Ferreira in the American Journal of Physics 79(10), 1009-1014 (2011) and has been approved by the authors and the American Journal of Physics (AJP) editor. The Confined Lennard-Jones Two Piston System was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_md_ConfinedLennardJonesTwoPistonSystem.jar file will run the program if Java is installed.

Christian, Wolfgang

2011-03-09

187

Confinement studies of ohmically heated plasmas in TFTR  

SciTech Connect

Systematic scans of density in large deuterium plasmas (a = 0.83 m) at several values of plasma current and toroidal magnetic field strength indicate that the total energy confinement time, tau/sub E/, is proportional to the line-average density anti n/sub e/ and the limiter q. Confinement times of approx. 0.3 s have been observed for anti n/sub e/ = 2.8 x 10/sup 19/ m/sup -3/. Plasma size scaling experiments with plasmas of minor radii a = 0.83, 0.69, 0.55, and 0.41 m at constant limiter q reveal a confinement dependence on minor radius. The major-radius dependence of tau/sub E/, based on a comparison between TFTR and PLT results, is consistent with R/sup 2/ scaling. From the power balance, the thermal diffusivity chi/sub e/ is found to be significantly less than the INTOR value. In the a = 0.41 m plasmas, saturation of confinement is due to neoclassical ion conduction (chi/sub i/ neoclassical >> chi/sub e/).

Efthimion, P.C.; Bretz, N.L.; Bell, M.G.; Bitter, M.; Blanchard, W.R.; Boody, F.; Boyd, D.; Bush, C.E.; Cecchi, J.L.; Coonrod, J.

1985-03-01

188

Multishell inertial confinement fusion target  

SciTech Connect

A method of fabricating multishell fuel targets for inertial confinement fusion usage. Sacrificial hemispherical molds encapsulate a concentric fuel pellet which is positioned by fiber nets stretched tautly across each hemispherical mold section. The fiber ends of the net protrude outwardly beyond the mold surfaces. The joint between the sacrificial hemispheres is smoothed. A ceramic or glass cover is then deposited about the finished mold surfaces to produce an inner spherical surface having continuously smooth surface configuration. The sacrificial mold is removed by gaseous reaction accomplished through the porous ceramic cover prior to enclosing of the outer sphere by addition of an outer coating. The multishell target comprises the inner fuel pellet concentrically arranged within a surrounding coated cover or shell by fiber nets imbedded within the cover material.

Holland, J.R.; Del Vecchio, R.M.

1984-10-23

189

Magnetic confinement of cosmic clouds  

NASA Technical Reports Server (NTRS)

The role of the magnetic field in the confinement or compression of interstellar gas clouds is reconsidered. The virial theorem for an isolated magnetized cloud in the presence of distant magnetic sources is reformulated in terms of moments of the internal and external currents, and an equilibrium condition is derived. This condition is applied to the interaction between isolated clouds for the simple- and artificial-case in which the field of each cloud is a dipole. With the simplest of statistical assumptions, the probability of any given cloud being compressed is calculated as about 10 percent, the magnetic field acting as a medium which transmits the kinetic pressure between clouds. Even when compression occurs the magnetic pressure 1/2 B-squared may decrease on leaving the cloud surface.

Azar, Michel; Thompson, W. B.

1988-01-01

190

Multishell inertial confinement fusion target  

DOEpatents

A method of fabricating multishell fuel targets for inertial confinement fusion usage. Sacrificial hemispherical molds encapsulate a concentric fuel pellet which is positioned by fiber nets stretched tautly across each hemispherical mold section. The fiber ends of the net protrude outwardly beyond the mold surfaces. The joint between the sacrificial hemispheres is smoothed. A ceramic or glass cover is then deposited about the finished mold surfaces to produce an inner spherical surface having continuously smooth surface configuration. The sacrificial mold is removed by gaseous reaction accomplished through the porous ceramic cover prior to enclosing of the outer sphere by addition of an outer coating. The multishell target comprises the inner fuel pellet concentrically arranged within a surrounding coated cover or shell by fiber nets imbedded within the cover material.

Holland, James R. (Butler, PA); Del Vecchio, Robert M. (Vandergrift, PA)

1984-01-01

191

Multishell inertial confinement fusion target  

DOEpatents

A method of fabricating multishell fuel targets for inertial confinement fusion usage. Sacrificial hemispherical molds encapsulate a concentric fuel pellet which is positioned by fiber nets stretched tautly across each hemispherical mold section. The fiber ends of the net protrude outwardly beyond the mold surfaces. The joint between the sacrificial hemispheres is smoothed. A ceramic or glass cover is then deposited about the finished mold surfaces to produce an inner spherical surface having continuously smooth surface configuration. The sacrificial mold is removed by gaseous reactions accomplished through the porous ceramic cover prior to enclosing of the outer sphere by addition of an outer coating. The multishell target comprises the inner fuel pellet concentrically arranged within a surrounding coated cover or shell by fiber nets imbedded within the cover material.

Holland, James R. (Butler, PA); Del Vecchio, Robert M. (Vandergrift, PA)

1987-01-01

192

Confined Zone Dispersion Project: A DOE assessment  

SciTech Connect

The goal of the US Department of Energy (DOE) Clean Coal Technology (CCT) program is to furnish the energy marketplace with a number of advanced, more efficient, and environmentally responsible coal utilization technologies through demonstration projects. These projects seek to establish the commercial feasibility of the most promising advanced coal technologies that have developed beyond the proof-of-concept (POC) stage. This document serves as a DOE post-project assessment of the Confined Zone Dispersion Project in CCT Round 3. In 1990, Bechtel Corporation entered into a cooperative agreement to conduct the demonstration project. The Seward Power Station of Pennsylvania Electric Company (now GPU Genco) was the host site. DOE funded 43 percent of the total project cost of $12,173,000. The project was started in June 1990 and was scheduled to be completed in June 1993. As a result of various operating problems, the schedule was extended into 1994 without additional cost to DOE. Bechtel provided the additional financing and GPU Genco provided electricity, steam, and water to operate the unit. The independent evaluation contained herein is based primarily on information from Bechtel's final technical report (1994) as well as other references cited. Confined Zone Dispersion (CZD) is a flue gas desulfurization (FGD) process that removes sulfur dioxide (SO{sub 2}). A finely atomized slurry of reactive lime, calcium hydroxide or Ca(OH){sub 2} is injected into the flue-gas duct work, between the air preheater and the second-stage ESP. The lime reacts with the SO{sub 2}, forming dry solid reaction products. The downstream ESP captures the 2 reaction products along with the fly ash entrained in the flue gas. The CZD process was demonstrated on Unit 5, a 147-MWe utility unit with two flue gas ducts. One of the ducts was extended to provide the requisite residence time and retrofitted with the CZD lime injection equipment.

NONE

1999-11-30

193

Order in very cold confined plasmas  

SciTech Connect

The study of the structure and dynamic properties of classical systems of charged particles confined by external forces, and cooled to very low internal energies, is the subject of this talk. An infinite system of identical charged particles has been known for some time to form a body-centered cubic lattice and is a simple classical prototype for condensed matter. Recent technical developments in storage rings, ion traps, and laser cooling of ions, have made it possible to produce such systems in the laboratory, though somewhat modified because of their finite size. I would like to discuss what one may expect in such systems and also show some examples of experiments. If we approximate the potential of an ion trap with an isotropic harmonic force F = {minus}Kr then the Hamiltonian for this collection of ions is the same as that for J. J. Thomson`s ``plum pudding`` model of the atom, where electrons were thought of as discrete negative charges imbedded in a larger, positive, uniformly charged sphere. The harmonic force macroscopically is canceled by the average space-charge forces of the plasma-, and this fixes the overall radius of the distribution. What remains, are the residual two-body Coulomb interactions that keep the particles within the volume as nearly equidistant as possible in order to minimize the potential energy. The configurations obtained for the minimum energy of small ionic systems [2] in isotropic confinement are shown in figure 1. Indeed this is an `Exotic Atom` and fits well into the subject of this symposium honoring the 60th birthday of Professor Toshi Yamazaki.

Schiffer, J.P. [Argonne National Lab., IL (United States)]|[Univ. of Chicago, Chicago, IL (United States)

1995-12-31

194

Quantum chemistry of confined systems: structure and vibronic spectra of a confined hydrogen molecule  

Microsoft Academic Search

Structure and spectral properties of the hydrogen molecule confined in a spherically symmetric harmonic oscillator potential were studied using the configuration interaction method. Increased strength of the confining potential exerts significant influence on the geometry of the molecule as well as on the vibronic transitions between the electronic ground and lowest excited singlet states. With increasing confinement strength the bond

Geerd H. F Diercksen; Mariusz Klobukowski

2001-01-01

195

Millisecond burning of confined energetic materials during cookoff  

SciTech Connect

The response of a system containing an energetic material (EM) to an abnormal thermal environment is termed cookoff. To predict the violence of reaction of confined energetic materials during cookoff requires a description of the relevant physical processes that occur on time scales Ranging from days to submicroseconds. The time-to-ignition can be characterized accurately using heat transfer with chemistry and quasistatic mechanics. After ignition the energetic material deflagrates on a millisecond time scale. During this time the mechanical processes become dynamic. If the confinement survives burning then accelerated deflagration can lead to shock formation and deflagration to detonation transition. The focus of this work is the dynamic combustion regime in the millisecond time domain. Due to the mathematical stiffness of the chemistry equations and the prohibitively fine spatial resolution requirements needed to resolve the structure of the flame, an interface tracking approach is used to propagate the burn front. Demonstrative calculations are presented that illustrate the dynamic interaction of the deflagrating energetic material with its confinement.

Schmitt, R.G.; Baer, T.A.

1997-11-01

196

Elmo Bumpy Square Plasma Confinement Device.  

National Technical Information Service (NTIS)

The invention is an Elmo bumpy type plasma confinement device having a polygonal configuration of closed magnet field lines for improved plasma confinement. In the preferred embodiment, the device is of a square configuration which is referred to as an El...

L. W. Owen

1984-01-01

197

MHD-Limits to Plasma Confinement  

Microsoft Academic Search

Ideal MHD restricts both the current and the pressure which can be stably confined in a Tokamak. A pressure profile optimisation is carried out for a variety of equilibria, which include JET and INTOR-like plasmas, in order to obtain the maximum ? which can be stably confined at constant current. The current is limited to a value corresponding to a

F. Troyon; R. Gruber; H. Saurenmann; S. Semenzato; S. Succi

1984-01-01

198

Inertial electrostatic confinement (IEC) neutron sources  

Microsoft Academic Search

Inertial electrostatic confinement (IEC) is one of the earliest plasma confinement concepts, having first been suggested by P.T. Farnsworth in the 1950s. The concept involves a simple apparatus of concentric spherical electrostatic grids or a combination of grids and magnetic fields. An electrostatic structure is formed from the confluence of electron or ion beams. Gridded IEC systems have demonstrated neutron

R. A. Nebel; D. C. Barnes; E. J. Caramana; R. D. Janssen; W. D. Nystrom; T. N. Tiouririne; B. C. Trent; G. H. Miley; J. Javedani

1995-01-01

199

Spraengning mot Kompakterat Berg (Confined Volume Blasting),  

National Technical Information Service (NTIS)

SveDeFo has performed halfscale tests with confined volume blasting in LKAB:s mine in Malmberget in order to find out if that gives an improvement in fragmentation. The answer is yes. The fragmentation is better in confined volume blasting compared to ord...

M. Olsson

1987-01-01

200

Degraded Confinement and Turbulence in Tokamak Experiments  

SciTech Connect

After a review on the state of tokamak transport theory, the methodology to derive experimental results will be described. Examples of confinement in ohmic plasmas and the deterioration with additional healing will be given. Some examples of improved confinement modes will be discussed. Fluctuation measurements and correlation with characteristic dimensionless numbers should give a clue to the unexplained phenomena.

Hogeweij, G.M.D. [FOM-Institute for Plasma Physics Rijnhuizen (Netherlands)

2004-03-15

201

Operational technology for greater confinement disposal  

Microsoft Academic Search

Procedures and methods for the design and operation of a greater confinement disposal facility using large-diameter boreholes are discussed. It is assumed that the facility would be located at an operating low-level waste disposal site and that only a small portion of the wastes received at the site would require greater confinement disposal. The document is organized into sections addressing:

P. T. Dickman; A. T. Vollmer; P. H. Hunter

1984-01-01

202

Tropical geometric interpretation of ultradiscrete singularity confinement  

NASA Astrophysics Data System (ADS)

Using the interpretation of the ultradiscretization procedure as a non-Archimedean valuation, we use results of tropical geometry to show how roots and poles manifest themselves in piece-wise linear systems as points of non-differentiability. This will allow us to demonstrate a correspondence between singularity confinement for discrete integrable systems and ultradiscrete singularity confinement for ultradiscrete integrable systems.

Ormerod, Christopher M.

2013-08-01

203

Waste-acceptance criteria for greater-confinement disposal  

SciTech Connect

A methodology for establishing waste-acceptance criteria based on quantitative performance factors that characterize the confinement capabilities of a waste-disposal site and facility has been developed. The methodology starts from the basic objective of protecting public health and safety by providing assurance that dispsoal of the waste will not result in a radiation dose to any member of the general public, in either the short or long term, in excess of an established basic dose limit. The method is based on an explicit, straightforward, and quantitative relationship among individual risk, confinement capabilities, and waste characteristics. A key aspect of the methodology is the introduction of a confinement factor that characterizes the overall confinement capability of a particular facility and can be used for quantitative assessments of the performance of different disposal sites and facilities, as well as for establishing site-specific waste-acceptance criteria. Confinement factors are derived by means of site-specific pathway analyses. They make possible a direct and simple conversion of a basic dose limit into waste-acceptance criteria, specified as concentration limits on radionuclides in the waste streams and expressed in quantitative form as a function of parameters that characterize the site, facility design, waste containers, and waste form. Waste-acceptance criteria can be represented visually as activity/time plots for various waste streams. These plots show the concentrations of radionuclides in a waste stream as a function of time and permit a visual, quantitative assessment of long-term performance, relative risks from different radionuclides in the waste stream, and contributions from ingrowth. 13 refs.

Gilbert, T.L.; Meshkov, N.K.

1986-01-01

204

A tug-of-war between electronic excitation and confinement in a dynamical context.  

PubMed

Quantum fluid density functional theory has been used to study the time evolution of various reactivity parameters such as hardness, electrophilicity, entropy, chemical potential, polarizability, electronegativity etc. in a confined environment during time dependent processes like atom-ion collision and atom-field interaction. Responses in the reactivity parameters of the helium atom, in the dynamical context, for ground state as well as in excited state, have been reported. The confinement is incorporated through a Dirichlet type boundary condition. With a decrease in the size of the cylindrical box, the system gets harder and less polarizable. Simultaneous excitation and confinement may bring back the ground state behavior. PMID:22195296

Sarkar, Utpal; Khatua, Munmun; Chattaraj, Pratim Kumar

2012-02-01

205

Confined dynamics of a single DNA molecule.  

PubMed

The effect of a slit-like confinement on the relaxation dynamics of DNA is studied via a mesoscale model in which a bead and spring model for the polymer is coupled to a particle-based Navier-Stokes solver (multi-particle collision dynamics). The confinement is found to affect the equilibrium stretch of the chain when the bulk gyration radius is comparable to or smaller than the channel height and our data are in agreement with the (R(g,bulk)/h)(1/4) scaling of the polymer extension in the wall tangential direction. Relaxation simulation at different confinements indicates that, while the overall behaviour of the relaxation dynamics is similar for low and strong confinements, a small, but significant, slowing of the far-equilibrium relaxation is found as the confinement increases. PMID:21536580

Chinappi, M; De Angelis, E

2011-06-13

206

Geometry of nuclear fusion diagnostic data on information manifolds with an application to fusion plasma confinement  

NASA Astrophysics Data System (ADS)

Pattern recognition is becoming an increasingly important tool for making inferences from the massive amounts of data produced in fusion experiments. The purpose is to contribute to physics studies and plasma control. In this work, we address the visualization of plasma confinement data and their dynamics, the identification of confinement regimes and the establishment of a scaling law for the energy confinement time. We take an intrinsically probabilistic approach, modeling data from the International Global H-mode Confinement Database with Gaussian distributions. We show that pattern recognition operations working in the associated probability space are considerably more powerful than their counterparts in a Euclidean data space. This opens up new possibilities for analyzing confinement data and for fusion data processing in general.

Verdoolaege, Geert; Karagounis, Giorgos; Van Oost, Guido

2013-08-01

207

Two flavor QCD and confinement  

SciTech Connect

We argue that the order of the chiral transition for N{sub f}=2 is a sensitive probe of the QCD vacuum, in particular, of the mechanism of color confinement. A strategy is developed to investigate the order of the transition by use of finite size scaling analysis. An in-depth numerical investigation is performed with staggered fermions on lattices with L{sub t}=4 and L{sub s}=12, 16, 20, 24, 32 and quark masses am{sub q} ranging from 0.01335 to 0.307036. The specific heat and a number of susceptibilities are measured and compared with the expectations of an O(4) second order and of a first order phase transition. A detailed comparison with previous works, which all use similar techniques as ours, is performed. A second order transition in the O(4) and O(2) universality classes are incompatible with our data, which seem to prefer a first order transition. However we have L{sub t}=4 and unimproved action, so that a check with improved techniques (algorithm and action) and possibly larger L{sub t} will be needed to assess this issue on a firm basis.

D'Elia, Massimo; Di Giacomo, Adriano; Pica, Claudio [Dipartimento di Fisica dell'Universita di Genova, Italy and INFN, Sezione di Genova, Via Dodecaneso 33, I-16146 Genova (Italy); Dipartimento di Fisica dell'Universita di Pisa, Italy and INFN, Sezione di Pisa, largo Pontecorvo 3, I-56127 Pisa (Italy)

2005-12-01

208

Simulation of spheromak evolution and energy confinement  

SciTech Connect

Simulation results are presented that illustrate the formation and decay of a spheromak plasma driven by a coaxial electrostatic plasma gun, and model the plasma energy confinement. The physics of magnetic reconnection during formation is also illuminated. The simulations are performed with the three-dimensional, time-dependent, resistive magnetohydrodynamic NIMROD code [C. R. Sovinec, A. H. Glasser, T. A. Gianakon, D. C. Barnes, R. A. Nebel, S. E. Kruger, D. D. Schnack, S. J. Plimpton, A. Tarditi, and M. S. Chu, J. Comput. Phys. 195, 355 (2004)]. The simulation results are compared to data from the Sustained Spheromak Physics Experiment (SSPX) [E. B. Hooper, L. D. Pearlstein, and R. H. Bulmer, Nucl. Fusion 39, 863 (1999)]. The simulation results are tracking SSPX with increasing fidelity (e.g., improved agreement with measured magnetic fields, fluctuation amplitudes, and electron temperature) as the simulation has been improved in its representations of the experimental geometry, the magnetic bias coils, and the detailed time dependence of the current source driving the plasma gun, and uses realistic parameters. The simulations confirm that controlling the magnetic fluctuations is influenced by the current drive history and by matching the gun current in sustainment approximately to the value corresponding to the eigenvalue in the flux-conserver for the parallel current in a force-free equilibrium.

Cohen, B.I.; Hooper, E.B.; Cohen, R.H.; Hill, D.N.; McLean, H.S.; Wood, R.D.; Woodruff, S.; Sovinec, C.R.; Cone, G.A. [University of California, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Department of Engineering Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706-1609 (United States)

2005-05-15

209

Simulation of Spheromak Evolution and Energy Confinement  

SciTech Connect

Simulation results are presented that illustrate the formation and decay of a spheromak plasma driven by a coaxial electrostatic plasma gun, and that model the energy confinement of the plasma. The physics of magnetic reconnection during spheromak formation is also illuminated. The simulations are performed with the three-dimensional, time-dependent, resistive magnetohydrodynamic NIMROD code. The simulation results are compared to data from the SSPX spheromak experiment at the Lawrence Livermore National Laboratory. The simulation results are tracking the experiment with increasing fidelity (e.g., improved agreement with measurements of the magnetic field, fluctuation amplitudes, and electron temperature) as the simulation has been improved in its representations of the geometry of the experiment (plasma gun and flux conserver), the magnetic bias coils, and the detailed time dependence of the current source driving the plasma gun, and uses realistic parameters. The simulations are providing a better understanding of the dominant physics in SSPX, including when the flux surfaces close and the mechanisms limiting the efficiency of electrostatic drive.

Cohen, B; Hooper, E; Cohen, R; Hill, D; McLean, H; Wood, R; Woodruff, S; Sovinec, C; Cone, G

2004-11-09

210

Simulation of Spheromak Evolution and Energy Confinement  

SciTech Connect

Simulation results are presented that illustrate the formation and decay of a spheromak plasma driven by a coaxial electrostatic plasma gun, and that model the energy confinement of the plasma. The physics of magnetic reconnection during spheromak formation is also illuminated. The simulations are performed with the three-dimensional, time-dependent, resistive magnetohydrodynamic NIMROD code. The dimensional, simulation results are compared to data from the SSPX spheromak experiment at the Lawrence Livermore National Laboratory. The simulation results are tracking the experiment with increasing fidelity (e.g., improved agreement with measurements of the magnetic field, fluctuation amplitudes, and electron temperature) as the simulation has been improved in its representations of the geometry of the experiment (plasma gun and flux conserver), the magnetic bias coils, and the detailed time dependence of the current source driving the plasma gun, and uses realistic parameters. The simulations are providing a better understanding of the dominant physics in SSPX, including when the flux surfaces close and the mechanisms limiting the efficiency of electrostatic drive.

Cohen, B; Hooper, E; Cohen, R; Hill, D; McLean, H; Wood, R; Woodruff, S

2004-11-12

211

Inertial confinement fusion driven by intense ion beams  

Microsoft Academic Search

All the basic and physical aspects of ion-driven confinement fusion are timely reviewed. Both light- and heavy-ion beams are stressed out. The fundamental components : accelerating structure, beam, target and reactor vessel are thoroughly presented. A particular emphasis is given to the three crucial interfaces : beam-reactor, beam-target and target-reactor. Ion-plasma experiments of closely related concern are also investigated at

C. Deutsch

1986-01-01

212

Relaxation of plasma rotation in toroidal magnetic confinement systems  

Microsoft Academic Search

A study is made of the relaxation of plasma rotation in nonaxisymmetric toroidal magnetic confinement systems, such as stellarators\\u000a and rippled tokamaks. In this way, a solution to the drift kinetic equation is obtained that explicitly takes into account\\u000a the time dependence of the distribution function, and expressions for the diffusive particle fluxes and longitudinal viscosity\\u000a are derived that make

L. M. Kovrizhnykh

2003-01-01

213

Preliminary studies of inertial-electrostatic confinement fusion experiments  

SciTech Connect

Preliminary inertial-electrostatic confinement fusion experiments have been carried out using hydrogen gas, and measurements of the light from a plasma core were made. The life time of charged particles in gridded IECF configuration is found to be longer than in the conventional spherical electrode discharges. The light intensity is found to be proportional to about 2/3 power of the input power. 9 refs., 6 figs.

Yamamoto, Yasushi; Ohnishi, Masami; Yoshikawa, Kiyoshi; Toku, Hisayuki; Hasegawa, Mitsunori; Matsuo, Takashi [Kyoto Univ. (Japan)

1996-12-31

214

FRP confined smart concrete/mortar  

NASA Astrophysics Data System (ADS)

In this study, fiber reinforced polymer (FRP) confined smart concrete/mortar sensors were invented and validated for significantly improved measurement range. Several trial mixes were made using cement mortar and micron-phase graphite powders at different mix proportions. Compressive loading tests were conducted on smart mortar cylinder specimens with or without FRP confinement. Two-probe method was used to detect the electrical resistance of the smart cement mortar specimens. Strong correlation was recognized between the stress and electric resistance of the smart mortar. The test results indicated that the FRP wrapping could significantly enlarge the range of such self-sensing property as a consequence of confinement.

Xiao, Y.; Zhu, P. S.; Choi, K. G.; Wu, Y. T.; Huang, Z. Y.; Shan, B.

2006-04-01

215

Propagating confined states in phase dynamics  

NASA Technical Reports Server (NTRS)

Theoretical treatment is given to the possibility of the existence of propagating confined states in the nonlinear phase equation by generalizing stationary confined states. The nonlinear phase equation is set forth for the case of propagating patterns with long wavelengths and low-frequency modulation. A large range of parameter values is shown to exist for propagating confined states which have spatially localized regions which travel on a background with unique wavelengths. The theoretical phenomena are shown to correspond to such physical systems as spirals in Taylor instabilities, traveling waves in convective systems, and slot-convection phenomena for binary fluid mixtures.

Brand, Helmut R.; Deissler, Robert J.

1992-01-01

216

Cascade inertial confinement fusion reactor concept.  

National Technical Information Service (NTIS)

The Cascade reactor concept has the potential of converting inertial confinement fusion (ICF) energy into electrical power safely, efficiently, and with low activation. Its flexibility permits a number of options for materials, blankets, fuel-pellet desig...

J. H. Pitts W. J. Hogan M. T. Tobin R. F. Bourque W. R. Meier

1990-01-01

217

Confinement studies for novel MCF reactor configurations  

NASA Astrophysics Data System (ADS)

Motivated by ideas from plasma theory, we use a suite of coupled plasma physics codes to explore the confinement performance of a range of tokamak configurations. The codes include GS2, Gryffin, Trinity and TOQ.

Dorland, William; Despain, Kate; Barnes, Michael; Parra, Felix; Highcock, Edmund; Schekochihin, Alex; Abel, Ian; Cowley, Steve

2010-11-01

218

Reorientational dynamics of water confined in zeolites.  

PubMed

We present a detailed molecular-dynamics study of water reorientation and hydrogen-bond dynamics in a strong confinement situation, within the narrow pores of an all-silica Linde type A (LTA) zeolite. Two water loadings of the zeolite are compared with the bulk case. Water dynamics are retarded in this extreme hydrophobic confinement and the slowdown is more pronounced at higher water loading. We show that water reorientation proceeds mainly by large-amplitude angular jumps, whose mechanism is similar to that determined in the bulk. The slowdown upon hydrophobic confinement arises predominantly from an excluded-volume effect on the large fraction of water molecules lying at the interface with the zeolite matrix, with an additional minor contribution coming from a structuring effect induced by the confinement. PMID:24449592

Fogarty, Aoife C; Coudert, François-Xavier; Boutin, Anne; Laage, Damien

2014-02-24

219

Density Induced Mixing in Confined Aquifers.  

National Technical Information Service (NTIS)

Analytical techniques are developed to describe the mixing between two fluids of different density in a confined aquifer, in which one fluid is introduced to the aquifer by well recharge. The immiscible displacement process in both linear and radial flows...

L. W. Gelhar J. L. Wilson J. S. Miller J. M. Hamrick

1972-01-01

220

Dynamic Testing of Laterally Confined Concrete.  

National Technical Information Service (NTIS)

For investigating the effects of deformation rate in confined deformation of concrete, a hydraulic pressure cell has been designed and installed on the 3-inch diameter Split-Hopkinson Pressure Bar (SHPB) system at the University of Florida. Plain concrete...

D. A. Jenkins L. E. Malvern

1990-01-01

221

C-141 Confined Space Technical Guidance Document.  

National Technical Information Service (NTIS)

The following information and instructions apply to permit-required and nonpermit-required confined spaces associated with the C-141 aircraft. The majority of activities conducted within these spaces are for inspections and routine scheduled maintenance o...

S. Kapranos, J. Costantion, T. J. Hintz

2002-01-01

222

C-17 Confined Space Technical Guidance Document.  

National Technical Information Service (NTIS)

The following information and instructions apply to permit-required and nonpermit-required confined spaces associated with the C-17 aircraft. The majority of activities conducted within these spaces are for inspections and routine scheduled maintenance on...

S. Kapranos, J. Costantino, T. J. Hintz

2002-01-01

223

KC-10 Confined Space Technical Guidance Document.  

National Technical Information Service (NTIS)

The following information and instructions apply to permit-required and nonpermit-required confined spaces associated with the KC-10 aircraft. The majority of activities conducted within these spaces are for inspections and routine scheduled maintenance o...

S. Kapranos, J. Costantino, T. J. Hintz

2002-01-01

224

Speeding up of sedimentation under confinement.  

PubMed

We show an increase of the sedimentation velocity as small particles are confined in circular capillaries. In general, confinement slows down sedimentation. But, we show that at low Reynolds numbers and in 1D confinement this is not the case. Particle sedimentation velocity is not homogeneous, which can lead to the formation of structures. These structures are enhanced and stabilized in the presence of walls and in the absence of other dissipative mechanisms. As a consequence, it is possible to achieve sedimentation velocities that even exceed the Stokes velocity. The segregation at critical capillary diameters has been directly observed using a large scale model. These simple experiments offer a new insight into the old problem of sedimentation under confinement. PMID:23679787

Heitkam, S; Yoshitake, Y; Toquet, F; Langevin, D; Salonen, A

2013-04-26

225

Inertial confinement fusion reactor cavity analysis  

SciTech Connect

This report discusses the following research topics on inertial confinement target chamber design: x-ray vaporization of first wall materials; liquid metal condensation experiment; droplet formation in ICF target chambers; and laboratory microfusion facility calculations.

MacFarlane, J.J.; Peterson, R.R.; Corradini, M.L.; Moses, G.A.; Bang, K.H.; Barry, J.J.

1989-07-01

226

Human Adaptation To Isolated And Confined Environments  

NASA Technical Reports Server (NTRS)

Data from Antarctic research station analyzed. Report describes study of physiology and psychology of humans in isolated and confined environment. Suggests ways in which such environments made more acceptable to human inhabitants.

Evans, Gary W.; Stokols, Daniel; Carrere, Sna Sybil

1992-01-01

227

Entropic force on granular chains self-extracting from one-dimensional confinement.  

PubMed

The entropic forces on the self-retracting granular chains, which are confined in channels with different widths, are determined. The time dependence of the length of chain remaining in the channel Lin(t) is measured. The entropic force is treated as the only parameter in fitting the solution of the nonlinear equation of motion of Lin(t) to the experimental data. The dependence of the entropic force on the width of the confining channel can be expressed as a power-law with an exponent of 1.3, which is consistent with the previous theoretical predictions for the entropy loss due to confinement. PMID:24437916

Jeng, Pei-Ren; Chen, KuanHua; Hwang, Gwo-jen; Cho, Ethan Y; Lien, Chenhsin; To, Kiwing; Chou, Y C

2014-01-14

228

Entropic force on granular chains self-extracting from one-dimensional confinement  

NASA Astrophysics Data System (ADS)

The entropic forces on the self-retracting granular chains, which are confined in channels with different widths, are determined. The time dependence of the length of chain remaining in the channel Lin(t) is measured. The entropic force is treated as the only parameter in fitting the solution of the nonlinear equation of motion of Lin(t) to the experimental data. The dependence of the entropic force on the width of the confining channel can be expressed as a power-law with an exponent of 1.3, which is consistent with the previous theoretical predictions for the entropy loss due to confinement.

Jeng, Pei-Ren; Chen, KuanHua; Hwang, Gwo-jen; Cho, Ethan Y.; Lien, Chenhsin; To, Kiwing; Chou, Y. C.

2014-01-01

229

Confined zone dispersion flue gas desulfurization demonstration  

SciTech Connect

The confined zone dispersion (CZD) process involves flue gas post-treatment, physically located between a boiler's outlet and its particulate collector, which in the majority of cases is an electrostatic precipitator. The features that distinguish this process from other similar injection processes are: Injection of an alkaline slurry directly into the duct, instead of injection of dry solids into the duct ahead of a fabric filter. Use of an ultrafine calcium/magnesium hydroxide, type S pressure-hydrated dolomitic lime. This commercial product is made from plentiful, naturally occurring dolomite. Low residence time, made possible by the high effective surface area of the Type S lime. Localized dispersion of the reagent. Slurry droplets contact only part of the gas while the droplets are drying, to remove up to 50 percent of the S0{sub 2} and significant amounts of NO{sub x}. The process uses dual fluid rather than rotary atomizers. Improved electrostatic precipitator performance via gas conditioning from the increased water vapor content, and lower temperatures. Supplemental conditioning with S0{sub 3} is not believed necessary for satisfactory removal of particulate matter.

Not Available

1992-02-27

230

Confining boundary conditions from dynamical coupling constants  

NASA Astrophysics Data System (ADS)

It is shown that it is possible to consistently and gauge invariantly formulate models where the coupling constant is a non-trivial function of a scalar field. In the U(1) case, the coupling to the gauge field contains a term of the form g(?)j?(A?+??B) where B is an auxiliary field and j? is the Dirac current. The scalar field ? determines the local value of the coupling of the gauge field to the Dirac particle. The consistency of the equations determines the condition ???j?=0 which implies that the Dirac current cannot have a component in the direction of the gradient of the scalar field. As a consequence, if ? has a soliton behaviour, like defining a bubble that connects two vacua, we obtain that the Dirac current cannot have a flux through the wall of the bubble, defining a confinement mechanism where the fermions are kept inside those bags. Consistent models with time dependent fine structure constant can be also constructed

Guendelman, E. I.; Steiner, R.

2014-06-01

231

Optical properties of matrix confined species  

NASA Astrophysics Data System (ADS)

A majority of optically functional materials can be perceived as a liaison between ionic or molecular guests and a more or less rigid host. The guests exhibit an optical function, whereas the host provides suitable space, both of them synergistically complementing each other. The embracement of guests and hosts is often very intimate, as e.g. in typical phosphors, where luminescent ions even become part of the host. While the host-guest terminology usually is not applied to such marriages, the term becomes appropriate, if the host grants some degrees of spatial freedom, yet giving order and structure to its guests. Zeolites, clays and inverse opals are porous materials naturally providing hospitable cavities, channels or other compartments, and at the same time the guests are often demanded to occupy preassigned positions within these, or to structurally adapt to the interior host topology. Whereas zeolites and clays are merely patient providers of guest space, inverse opals, can actively turn the light on and off. The present article summarises and highlights recent experimental evidence, ongoing research and some envisaged merits resulting from the interaction of matrix confined luminescent ions, complexes and molecules with a focus on the optical properties of rare earth based materials.

Lezhnina, M. M.; Kynast, U. H.

2010-11-01

232

Dynamics of supercooled water in confined geometry  

NASA Astrophysics Data System (ADS)

As with most liquids, it is possible to supercool water; this generally involves cooling the liquid below its melting temperature (avoiding crystallization) until it eventually forms a glass. The viscosity and related relaxation times (?) of glass-forming liquids typically show non-Arrhenius temperature (T) dependencies. Liquids with highly non-Arrhenius behaviour in the supercooled region are termed `fragile'. In contrast, liquids whose behaviour is close to the Arrhenius law (ln? ~ 1/T) are termed `strong' ( ref. 5). A unique `fragile-strong' transition around 228K has been proposed for supercooled water; however, experimental studies of bulk supercooled water in this temperature range are generally hampered because crystallization occurs. Here we use broad-band dielectric spectroscopy to study the relaxation dynamics of supercooled water in a wide temperature range, including the usually inaccessible temperature region. This is possible because the supercooled water is held within a layered vermiculite clay-the geometrical confinement and presence of intercalated sodium ions prevent most of the water from crystallizing. We find a relaxational process with an Arrhenius temperature dependence, consistent with the proposed strong nature of deeply supercooled bulk water. Because water that is less supercooled has been established as highly fragile, our results support the existence of a fragile-strong transition.

Bergman, R.; Swenson, J.

2000-01-01

233

Dynamics of supercooled water in confined geometry  

PubMed

As with most liquids, it is possible to supercool water; this generally involves cooling the liquid below its melting temperature (avoiding crystallization) until it eventually forms a glass. The viscosity and related relaxation times (tau) of glass-forming liquids typically show non-Arrhenius temperature (T) dependencies. Liquids with highly non-Arrhenius behaviour in the supercooled region are termed 'fragile'. In contrast, liquids whose behaviour is close to the Arrhenius law (In tau infinity 1/T) are termed 'strong'. A unique 'fragile-strong' transition around 228 K has been proposed for supercooled water; however, experimental studies of bulk supercooled water in this temperature range are generally hampered because crystallization occurs. Here we use broad-band dielectric spectroscopy to study the relaxation dynamics of supercooled water in a wide temperature range, including the usually inaccessible temperature region. This is possible because the supercooled water is held within a layered vermiculite clay-the geometrical confinement and presence of intercalated sodium ions prevent most of the water from crystallizing. We find a relaxational process with an Arrhenius temperature dependence, consistent with the proposed strong nature of deeply supercooled bulk water. Because water that is less supercooled has been established as highly fragile, our results support the existence of a fragile-strong transition. PMID:10659841

Bergman; Swenson

2000-01-20

234

Vorticity confinement technique for drag prediction  

NASA Astrophysics Data System (ADS)

This work couples wake-integral drag prediction and vorticity confinement technique (VC) for the improved prediction of drag from CFD simulations. Induced drag computations of a thin wing are shown to be more accurate than the more widespread method of surface pressure integration when compared to theoretical lifting-line value. Furthermore, the VC method improves trailing vortex preservation and counteracts the shift from induced drag to numerical entropy drag with increasing distance of Trefftz plane downstream of the wing. Accurate induced drag prediction via the surface integration of pressure barring a sufficiently refined surface grid and increased computation time. Furthermore, the alternative wake-integral technique for drag prediction suffers from numerical dissipation. VC is shown to control the numerical dissipation with very modest computational overhead. The 2-D research code is used to test specific formulations of the VC body force terms and illustrate the computational efficiency of the method compared to a ``brute force'' reduction in spatial step size. For the 3-D wing simulation, ANSYS FLUENT is employed with the VC body force terms added to the solver with user-defined functions (UDFs). VC is successfully implemented to highly unsteady flows typical for Micro Air Vehicles (MAV) producing oscillative drag force either by natural vortex shedding at high angles of attack or by flapping wing motion.

Povitsky, Alex; Snyder, Troy

2011-11-01

235

Nuclear relaxation of liquids in confinements.  

PubMed

We study theoretically the effects of geometrical confinement on the dipolar relaxation of a non-interacting liquid in porous media. Application to the 1H relaxation of methylcyclohexane liquid in porous silica glasses is given. The case of an interacting liquid is considered by molecular dynamics simulations. Geometrical confinement and surface interaction lead to similar frequency behaviour of relaxation rates according to the layering of local density and anisotropy of the molecular mobility. PMID:8170294

Korb, J P; Delville, A; Xu, S; Jonas, J

1994-01-01

236

Interactions of Inert Confiners with Explosives  

Microsoft Academic Search

The deformation of an inert confiner by a steady detonation wave in an adjacent explosive is investigated for cases where\\u000a the confiner is sufficiently strong (or the explosive sufficiently weak) such that the overall change in the sound speed of\\u000a the inert is small. A coupling condition which relates the pressure to the deflection angle along the explosive-inert interface\\u000a is

G. J. Sharpe; J. B. Bdzil

2006-01-01

237

Visualization of a confined accelerated bubble  

Microsoft Academic Search

.   High-speed photography was used to study the collapse of a confined two-dimensional, air cavity in water, subjected to a\\u000a propagating pressure disturbance. The 5–6 mm diameter cavity was confined in a rectangular duct. A sustained pressure disturbance\\u000a was created by an accelerating piston in contact with the water 240 mm away from the bubble. The pressure increased from 0.1

F. K. Lu; X. Zhang

1999-01-01

238

Decoupling of Confined Normal 3He  

NASA Astrophysics Data System (ADS)

Anodic bonding was used to fabricate a 10 mm diameter × 640 nm tall annular geometry suitable for torsion pendulum studies of confined 3He. For pure 3He at saturated vapor pressure the inertia of the confined fluid was seen to be only partially coupled to the pendulum at 160 mK. Below 100 mK the liquid’s inertial contribution was negligible, indicating a complete decoupling of the 3He from the pendulum.

Dimov, S. G.; Bennett, R. G.; Ilic, B.; Verbridge, S. S.; Levitin, L. V.; Fefferman, A. D.; Casey, A.; Saunders, J.; Parpia, J. M.

2010-01-01

239

Programmed environment management of confined microsocieties  

NASA Technical Reports Server (NTRS)

A programmed environment is described that assists the implementation and management of schedules governing access to all resources and information potentially available to members of a confined microsociety. Living and work schedules are presented that were designed to build individual and group performance repertoires in support of study objectives and sustained adaptation by participants. A variety of measurement requirements can be programmed and standardized to assure continuous assessment of the status and health of a confined microsociety.

Emurian, Henry H.

1988-01-01

240

Inertial confinement fusion reactor for space applications  

Microsoft Academic Search

One of the most exciting and promising approaches to fusion power that has emerged recently is the magnetically insulated inertial confinement fusion (MICF) concept proposed by Hasegawa et al. It is a scheme that combines the benefits of magnetic and inertial fusions in which a plasma with a density of approx.10²¹ cm⁻³ is confined by the inertia of a heavy

T. Kammash; D. L. Galbraith

1986-01-01

241

Confinement studies of neutral beam heated discharges in TFTR  

SciTech Connect

The TFTR tokamak has reached its original machine design specifications (I/sub p/ = 2.5 MA and B/sub T/ = 5.2T). Recently, the D/sup 0/ neutral beam heating power has been increased to 6.3 MW. By operating at low plasma current (I/sub p/ approx. = 0.8 MA) and low density anti n/sub e/ approx. = 1 x 10/sup 19/m/sup -3/), high ion temperatures (9 +- keV) and rotation speeds (7 x 10/sup 5/ m/s) have been achieved during injection. At the opposite extreme, pellet injection into high current plasmas has been used to increase the line-average density to 8 x 10/sup 19/m/sup -3/ and the central density to 1.6 x 10/sup 20/m/sup -3// This wide range of operating conditions has enabled us to conduct scaling studies of the global energy confinement time in both ohmically and beam heated discharges as well as more detailed transport studies of the profile dependence. In ohmic discharges, the energy confinement time is observed to scale linearly with density only up to anti n/sub e/ approx. 4.5 x 10/sup 19/m/sup -3/ and then to increase more gradually, achieving a maximum value of approx. 0.45 s. In beam heated discharges, the energy confinement time is observed to decrease with beam power and to increase with plasma current. With P/sub b/ = 5.6 MW, anti n/sub e/ = 4.7 x 10/sup 19/m/sup -3/, I/sub p/ = 2.2 MA and B/sub T = 4.7T, the gross energy confinement time is 0.22 s and T/sub i/(0) = 4.8 keV. Despite shallow penetration of D/sup 0/ beams (at the beam energy less than or equal to 80 keV with low species yield), tau/sub E/(a) values are as large as those for H/sup 0/ injection, but central confinement times are substantially greater. This is a consequence of the insensitivity of the temperature and safety factor profile shapes to the heating profile. The radial variation of tau/sub E/ is even more pronounced with D/sup 0/ injection into high density pellet-injected plasmas. 25 refs.

Murakami, M.; Arunasalam, V.; Bell, J.D.; Stauffer, F.; Bell, M.G.; Bitte, M.; Blanchard, W.R.; Boody, F.; Britz, N.

1985-11-01

242

Dynamic flow and failure of confined polymethylmethacrylate  

NASA Astrophysics Data System (ADS)

The static and dynamic mechanical behavior of confined commercial polymethylmethacrylate (PMMA) is investigated. Cylindrical specimens are confined by means of a tightly fit metal sleeve and subjected to compression tests. The rate and pressure sensitivity of PMMA are characterized over a range of strain rates of ??=10-104 s. In the quasi-static regime, the material is quite ductile, exhibiting noticeable barreling. The dynamic failure mode consists of axial splitting and fragmentation at the lower strain rates ( ??<2000 s) and confining pressures. But, at the higher strain rates and confining pressures, the failure mode changes to adiabatic shear formation of a conical plug. This failure mode transition, identified by SEM fractographic analysis, can be explained by the fact that the confinement delays the operation of damage micromechanisms, as evidenced from the post-peak slope. The response of this polymer is described using a fitted rate-dependent Drucker-Prager pressure-sensitive model, according to ?=66.78?+0.223p, for 10????104 s. This work shows that confining PMMA turns this brittle material into a ductile one, exactly like other brittle materials such as ceramics. The present results thus fit into a general description of the pressure induced brittle-ductile transition, including rate sensitivity effects for this material.

Rittel, D.; Brill, A.

243

Microscale Confinement features in microfluidic devices can affect biofilm  

SciTech Connect

Biofilms are aggregations of microbes that are encased by extra-cellular polymeric substances (EPS) and adhere to surfaces and interfaces. Biofilm development on abiotic surfaces is a dynamic process, which typically proceeds through an initial phase of adhesion of plankntonic microbes to the substrate, followed by events such as growth, maturation and EPS secretion. However, the coupling of hydrodynamics, microbial adhesion and biofilm growth remain poorly understood. Here, we investigate the effect of semiconfined features on biofilm formation. Using a microfluidic device and fluorescent time-lapse microscopy, we establish that confinement features can significantly affect biofilm formation. Biofilm dynamics change not only as a function of confinement features, but also of the total fluid flow rate, and our combination of experimental results and numerical simulations reveal insights into the link between hydrodynamics and biofilm formation.

Kumar, Aloke [ORNL] [ORNL; Karig, David K [ORNL] [ORNL; Neethirajan, Suresh [University of Guelph] [University of Guelph; Acharya, Rajesh K [ORNL] [ORNL; Mukherjee, Partha P [ORNL] [ORNL; Retterer, Scott T [ORNL] [ORNL; Doktycz, Mitchel John [ORNL] [ORNL

2013-01-01

244

The deflection of a jet by confining surfaces  

NASA Technical Reports Server (NTRS)

Thrust vectoring can be provided by the turning of a jet exhaust by the presence of confining surfaces. This approach is analogous to the upper surface blowing (USB) concept. Mean velocities, velocity autocorrelations, and pressure-velocity correlations are measured. From the autocorrelation curves, the Taylor microscales and the integral length scales are calculated. Convection velocities are calculated from the velocity space-time correlations. Two different confining surfaces (one flat, one with large curvature) are placed adjacent to the lip of a circular nozzle, and the resultant effects on the flow field are determined. In addition, two velocity ratios (exit plane velocity to ambient stream velocity) are examined. The velocity measurements were made with a laser Doppler velocimeter in conjunction with a phase locked-loop processor. Pressure measurements were made using a 1/8th inch condensor type microphone.

Catalano, G. D.; Morton, J. B.; Humphris, R. R.

1981-01-01

245

Classical scattering of charged particles confined on an inhomogeneous helix  

NASA Astrophysics Data System (ADS)

We explore the effects arising due to the coupling of the center of mass and relative motion of two charged particles confined on an inhomogeneous helix with a locally modified radius. It is first proven that a separation of the center of mass and the relative motion is provided if and only if the confining manifold represents a homogeneous helix. In this case, bound states of repulsively Coulomb interacting particles occur. For an inhomogeneous helix, the coupling of the center of mass and relative motion induces an energy transfer between the collective and relative motion, leading to dissociation of initially bound states in a scattering process. Due to the time reversal symmetry, a binding of the particles out of the scattering continuum is thus equally possible. We identify the regimes of dissociation for different initial conditions and provide an analysis of the underlying phase space via Poincaré surfaces of section. Bound states inside the inhomogeneity as well as resonant states are identified.

Zampetaki, A. V.; Stockhofe, J.; Krönke, S.; Schmelcher, P.

2013-10-01

246

Load-induced confinement activates diamond lubrication by water.  

PubMed

Tribochemical reactions are chemical processes, usually involving lubricant or environment molecules, activated at the interface between two solids in relative motion. They are difficult to be monitored in situ, which leaves a gap in the atomistic understanding required for their control. Here we report the real-time atomistic description of the tribochemical reactions occurring at the interface between two diamond films in relative motion, by means of large scale ab initio molecular dynamics. We show that the load-induced confinement is able to catalyze diamond passivation by water dissociative adsorption. Such passivation decreases the energy of the contacting surfaces and increases their electronic repulsion. At sufficiently high coverages, the latter prevents surface sealing, thus lowering friction. Our findings elucidate effects of the nanoscale confinement on reaction kinetics and surface thermodynamics, which are important for the design of new lubricants. PMID:24138257

Zilibotti, G; Corni, S; Righi, M C

2013-10-01

247

Study of eliminating fire dampers to maintain process confinement  

SciTech Connect

Fire dampers are required by NFPA 90A to maintain the integrity of fire areas. However, several fire dampers in the Defense Waste Processing Facility (DWPF) Vitrification Building at the Savannah River site are proposed to be eliminated in order to maintain the integrity of the process confinement system. In accordance with NFPA (1989), the closing operation of each fire damper should be tested biannually. Fire damper testing must consider the situation where there is a damper hangup in tripping or resetting taking several minutes or more. A fire will also close these dampers. Bechtel performed a fire damper simulation study of the heating, ventilation, and air conditioning (HVAC) system with a computer model. The study showed that 39 of 103 fire dampers, closed one at a time, causes ventilation system backflow, which upsets the integrity of the process confinement system. Elimination of the fire dampers will prevent a backflow upset.

Davis, P.L. (Westinghouse Savannah River Co., Aiken, SC (United States)); Walling, R.C.; Patel, J.B.; Strunk, A.J.

1991-01-01

248

Confinement and power balance in the S-1 spheromak  

SciTech Connect

The confinement and scaling features of the S-1 spheromak have been investigated using magnetic, spectroscopic, and Thomson scattering data in conjunction with numerical modeling. Results from the multipoint Thomson scattering diagnostic shows that the central beta remains constant (/beta//sub to/ /approximately/ 5%) as the plasma current density increases from 0.68--2.1 MA/m/sup 2/. The density is observed to increase slowly over this range, while the central electron temperature increases much more rapidly. Analysis of the global plasma parameters shows a decrease in the volume average beta and energy confinement as the total current is increased. The power balance has been modeled numerically with a 0-D non-equilibrium time-dependent coronal model and is consistent with the experimental observations. 20 refs., 12 figs., 2 tabs.

Levinton, F.M.; Meyerhofer, D.D.; Mayo, R.M.; Janos, A.C.; Ono, Y.; Ueda, Y.; Yamada, M.

1989-07-01

249

Photon-Assisted Confinement-Induced Resonances for Ultracold Atoms  

NASA Astrophysics Data System (ADS)

We solve the two-particle s-wave scattering for an ultracold-atom gas confined in a quasi-one-dimensional trapping potential which is periodically modulated. The interaction between the atoms is included via Fermi's pseudopotential. For a modulated isotropic transverse harmonic confinement, the atomic center of mass and relative degrees of freedom decouple and an exact solution is possible. The modulation opens additional photon-assisted resonant scattering channels. Applying the Bethe-Peierls boundary condition, we obtain the general scattering solution of the time-dependent Floquet-Schrödinger equation which is universal at low energies. The effective one-dimensional scattering length can be controlled by the external driving.

Leyton, Vicente; Roghani, Maryam; Peano, Vittorio; Thorwart, Michael

2014-06-01

250

Port output of metallo-dielectric confined circular microlasers.  

PubMed

Port output of metallo-dielectric confined circular microlasers directly connected with a coupling waveguide in radial direction is presented and numerically investigated by the finite-difference time-domain method and the Padé approximation. The quality factors of fundamental whispering-gallery modes confined in microlasers with dimensions of around 1 ?m do not deteriorate until the output waveguide can support a one-order guided wave. The port-output metallo-dielectric microlasers with low threshold are expected. In addition, the mode characteristics of port-output metallo-dielectric microlasers are studied based on ample modes of larger cavity, where coupled modes and standing-wave-like modes dominate in the cavity with a wide output port. PMID:21499361

Che, Kai-Jun; Huang, Yong-Zhen; Xu, Hui-Ying; Cai, Zhi-Ping

2011-04-15

251

Ignition and burn in inertially confined magnetized fuel  

SciTech Connect

At the third International Conference on Emerging Nuclear Energy Systems, we presented computational results which suggested that breakeven'' experiments in inertial confinement fusion (ICF) may be possible with existing driver technology. We recently used the ICF simulation code LASNEX to calculate the performance of an idealized magnetized fuel target. The parameter space in which magnetized fuel operates is remote from that of both conventional'' ICF and magnetic confinement fusion devices. In particular, the plasma has a very high {beta} and is wall confined, not magnetically confined. The role of the field is to reduce the electron thermal conductivity and to partially trap the DT alphas. The plasma is contained in a pusher which is imploded to compress and adiabatically heat the plasma from an initial condition of preheat and pre-magnetization to the conditions necessary for fusion ignition. The initial density must be quite low by ICF standards in order to insure that the electron thermal conductivity is suppressed and to minimize the generation of radiation from the plasma. Because the energy loss terms are effectively suppressed, the implosion may proceed at a relatively slow rate of about 1 to 3 cm/{mu}s. Also, the need for low density fuel dictates a much larger target, so that magnetized fuel can use drivers with much lower power and power density. Therefore, magnetized fuel allows the use of efficient drivers that are not suitable for laser or particle beam fusion due to insufficient focus or too long pulse length. The ignition and burn of magnetized fuel involves very different dominant physical processes than does conventional'' ICF. The fusion time scale becomes comparable to the hydrodynamic time scale, but other processes that limit the burn in unmagnetized fuel are of no consequence. The idealized low gain magnetized fuel target presented here is large and requires a very low implosion velocity. 11 refs.

Kirkpatrick, R.C.; Lindemuth, I.R.

1991-01-01

252

Momentum Confinement on DIII-D with Low Net Neutral Beam Torque  

Microsoft Academic Search

Momentum confinement was investigated in ELMing H-mode plasmas with elevated qmin. Torque scans were performed at constant betaN, and the rotation profile was measured using charge exchange recombination (CER) spectroscopy. Studies of the mechanical angular momentum in the plasma show a non-uniform response to the applied neutral beam torque, resulting in a torque dependence of the momentum confinement time. Under

W. M. Solomon; R. V. Budny; D. Mikkelsen; R. Nazikian; S. D. Scott; M. C. Zarnstorff; K. H. Burrell; J. S. Degrassie; R. J. Groebner; J. E. Kinsey; C. C. Petty

2007-01-01

253

Particle confinement during lower-hybrid current drive in the Versator 2 Tokamak  

NASA Astrophysics Data System (ADS)

Increases in average density were observed during lower hybrid current drive (LACD) on the Versator II Tokamak and in other LHCD experiments where inductive and lower hybrid current drive are combined. Results of an extensive study of this density increase are presented showing that the increase is the result of an improvement in particle confinement time, tau/sub p/, compared to ohmic discharges with comparable parameters. The improved confinement appears when the Parail-Pogutse relaxation mode is stabilized during LHCD.

Chen, K. I.; Luckhardt, S. C.; Mayberry, M. J.; Porkolab, M.; Rohatgi, R.

1984-03-01

254

Magnetic bion condensation: A new mechanism of confinement and mass gap in four dimensions  

Microsoft Academic Search

In recent work, we derived the long-distance confining dynamics of certain QCD-like gauge theories formulated on small $S^1 \\\\times \\\\R^3$ based on symmetries, an index theorem, and Abelian duality. Here, we give the microscopic derivation. The solution reveals a new mechanism of confinement in QCD(adj) in the regime where we have control over both perturbative and nonperturbative aspects. In particular,

Mithat Unsal

2007-01-01

255

Dynamical screening of the Coulomb interaction for two confined electrons in a magnetic field  

Microsoft Academic Search

We show that a difference in time scales of vertical and lateral dynamics permits one to analyze the problem of interacting electrons confined in an axially symmetric three-dimensional potential with a lateral oscillator confinement by means of the effective two-dimensional Hamiltonian with a screened Coulomb interaction. Using an adiabatic approximation based on action-angle variables, we present solutions for the effective

N. S. Simonovic; R. G. Nazmitdinov

2008-01-01

256

Energy confinement and MHD activity in shaped TCV plasmas with localized electron cyclotron heating  

Microsoft Academic Search

Confinement in TCV electron cyclotron heated discharges was studied as a function of plasma shape, i.e. as a function of elongation, 1.1 < kappa< 2.15, and triangularity, -0.65 <= delta <= 0.55. The electron energy confinement time was found to increase with elongation, owing in part to the increase of plasma current with elongation. The beneficial effect of negative triangularities

A. Pochelon; T. P. Goodman; M. Henderson; C. Angioni; R. Behn; S. Coda; F. Hofmann; J.-P. Hogge; N. Kirneva; A. A. Martynov; J.-M. Moret; Z. A. Pietrzyk; F. Porcelli; H. Reimerdes; J. Rommers; E. Rossi; O. Sauter; M. Q. Tran; H. Weisen; S. Alberti; S. Barry; P. Blanchard; P. Bosshard; R. Chavan; B. P. Duval; Y. V. Esipchuck; D. Fasel; A. Favre; S. Franke; I. Furno; P. Gorgerat; P.-F. Isoz; B. Joye; J. B. Lister; X. Llobet; J.-C. Magnin; P. Mandrin; A. Manini; B. Marlétaz; P. Marmillod; Y. Martin; J.-M. Mayor; J. Mlynar; C. Nieswand; P. J. Paris; A. Perez; R. A. Pitts; K. A. Razumova; A. Refke; E. Scavino; A. Sushkov; G. Tonetti; F. Troyon; W. Van Toledo; P. Vyas

1999-01-01

257

Metallically confined microdisks with in-plane multiple guided emissions.  

PubMed

We theoretically present in-plane multiple guided emissions of metallically confined microdisk lasers which can be applied to drive multiple elements in compact photonic integration at the same time. Two to four-port microdisks with transverse magnetic and electric polarizations are investigated based on finite difference time domain simulation and padé approximation. Modes filtering of coupling ports are verified by the calculated mode quality factors (Q) which are decided by the matching of coupling ports with the energy density distribution of corresponding modes. Single mode lasing operation of semiconductor microdisk with guided emissions is possibly realized by selectively pumping. PMID:21935177

Che, Kai-Jun; Huang, Yong-Zhen; Chen, Lu-Jian; Cai, Zhi-Ping; Xu, Hui-Ying

2011-09-12

258

Ordering and disordering effects in confined liquid crystals  

Microsoft Academic Search

Confined liquid crystals exhibit significantly different physical properties from those of a bulk. The confinement could have either ordering or disordering effects on a liquid crystal (LC) phase depending on the topology of the confining surface and on the surface-LC interaction. This dissertation presents a deuteron nuclear magnetic resonance (DNMR) study of confined nCB liquid crystals, focusing on the surface

Tao Jin

2003-01-01

259

Stiffness and Confinement Ratios of SMA Wire Jackets for Confining Concrete  

NASA Astrophysics Data System (ADS)

This article discusses the effects of the stiffness and confinement ratios of shape memory alloy (SMA) wire jackets on the behavior of confined concrete. SMA wire jackets are an effective confining material to improve concrete behavior; for example, by increasing peak strength and failure strain. The stiffness and confinement ratios of fiber-reinforced polymer jackets have been extensively discussed and their effects are well known. However, assessment of the stiffness and confinement ratios of SMA wire jackets has not previously been conducted. In this study, we investigate the effects of the stiffness and confinement ratios of steel jackets, and then compare the results with those of SMA wire jackets. In general, the stiffness ratios of SMA wire jackets are relatively smaller than those of steel jackets, and most of them have lower stiffness ratios because the Young's moduli of the SMAs are relatively small. The active confining pressure of the SMA wires does not improve the lower stiffness-ratio effect since the amount of active confining pressure is not sufficiently large.

Richardson, P. L.; Lutjeharms, J. R. E.; Boebel, O.

2014-05-01

260

Global energy confinement studies on the Pegasus Toroidal Experiment  

NASA Astrophysics Data System (ADS)

Recent studies have shown that low-recycling walls significantly enhance L-mode energy confinement [1]. Discharges on Pegasus suggest a low-recycling regime is obtained using titanium gettering and cryogenic pumping. When the external gas supply is terminated during an established discharge, tangential H? and visible light signals drop to 5% of their initial levels within 5 ms. Wall recycling is measured using the density decay rate, and its effect on particle and energy confinement on Pegasus is explored. Initial global energy confinement times of ?E = 2 -- 4 ms were calculated for IP˜ 0.15 MA L-mode discharges. Scans of plasma current and line-averaged density are used to benchmark ?E measurements against empirical L-mode scaling laws. These initial ?E measurements indicate the H-mode power threshold as given by the ITPA04 scaling [2] can be exceeded in diverted Ohmic discharges on Pegasus. [1] Majeski, R. et al. Phy. Rev. Lett. 97 2006 075002 [2] Takizuka, T. et al. Plasma Phys. Control. Fusion 46 2004 A227

Battaglia, D. J.; Frost, M. J.; Garstka, G. D.; Sontag, A. C.; Unterberg, E. A.; Winz, G. R.

2007-11-01

261

Confinement jumps in a non-neutral plasma  

NASA Astrophysics Data System (ADS)

Measurements of confinement jumps in pure electron plasmas confined on magnetic surfaces are presented and discussed. The experiments were performed in the Columbia non-neutral torus stellarator [T. S. Pedersen, J. P. Kremer, R. G. Lefrancois, Q. Marksteiner, N. Pomphrey, W. Reiersen, F. Dahlgren, and X. Sarasola, Fusion Sci. Technol. 50, 372 (2006)]. The jumps exhibit hysteresis and are associated with a negative differential resistance. The jumps occur at particular emission currents of the biased emissive filaments that create and sustain the electron plasmas independent of the methods used to affect the emission current. This observation, as well as other experimental evidence, supports that the jumps are caused by a cathode instability. The jumps can also be triggered by the application of a bias potential on a nearby mesh. In most circumstances, the jumps occur between two stable but measurably different equilibrium states. These different equilibrium states have substantially different confinement times. The cathode physics is important for the jumps because the cathode instability provides the perturbation that triggers the jump of the whole plasma into the other equilibrium state, but as mentioned, an external electrostatic perturbation is also capable of triggering such a jump.

Hahn, Michael; Pedersen, Thomas Sunn; Brenner, Paul W.; Marksteiner, Quinn

2009-02-01

262

Confinement and water quality-induced stress in largemouth bass  

SciTech Connect

Plasma values of corticosteroids, glucose, chloride, and osmolality were determined in largemouth bass Micropterus salmoides under various environmental conditions. No differences were observed in quiescent fish due to sex, size, time of day, or the types of holding facilities tested (tanks, raceways, ponds). Differences were observed in plasma glucose, chloride, and osmolality values among fish acclimated to 10, 16, and 23 C. Abrupt temperature changes caused elevations in plasma corticosteroid and glucose concentrations and reduced plasma chloride and osmolality. Confinement in a net, for up to 48 hours, caused elevated glucose and corticosteroids and reduced chloride and osmolality values. After 48 hours of confinement, fish required up to 14 days to recover normal plasma characters. Generally, short-term exposure to poor water quality (high concentrations of CO/sub 2/ and NH/sub 3/, and low concentrations of dissolved oxygen) altered plasma corticosteroids and glucose but had little effect on plasma chloride or osmolality. Net confinement plus poor water quality caused additional stress. Plasma glucose and corticosteroid values were good indicators of stress during application of acute stressors whereas chloride and osmolality were useful indicators of long-term stress and patterns of recovery after stressors were removed.

Carmichael, G.J.; Tomasso, J.R.; Simco, B.A.; Davis, K.B.

1984-11-01

263

Dynamical Masses and Confinement in QED{sub 3}  

SciTech Connect

Dynamical Chiral Symmetry Breaking (DCSB) and Confinement are two crucial features of QCD which are responsible for the nature of the hadronic spectrum. A simpler model which exhibits both is quantum electrodynamics in (2+1) space-time dimensions, QED{sub 3}. A long standing debate in this model is the existence of a critical number of fermion families, N{sub c}, above which DCSB ceases to take place. This was established from the solutions of the Schwinger-Dyson equations (SDEs), in the leading order of the 1/N expansion in the Landau gauge. Confinement has also been found to be absent in this scenario. In this work, we study the stability of the solutions to the said SDEs under a variation of gauge while still working with the bare vertex. We find that the Landau gauge is the only gauge which exhibits the above mentioned results. Away from this gauge, DCSB takes place for an arbitrarily large N and confinement is reinstated. Attempting to understand this apparent inconsistency, we argue that in order to maintain the gauge covariance of the results, full vertex has to be employed in other gauges and/or constraints like the Landau-Khalatnikov-Fradkin transformations must be employed in going from Landau gauge to other gauges.

Raya, Alfredo; Madrigal, Sanchez [Instituto de Fisica y Matematicas, Universidad Michoacana de San Nicolas de Hidalgo. Apartado Postal 2-82, C.P. 58040, Morelia, Mich. (Mexico)

2008-07-02

264

Nonlocal effects in a hybrid plasmonic waveguide for nanoscale confinement.  

PubMed

The effect of nonlocal optical response is studied for a novel silicon hybrid plasmonic waveguide (HPW). Finite element method is used to implement the hydrodynamic model and the propagation mode is analyzed for a hybrid plasmonic waveguide of arbitrary cross section. The waveguide has an inverted metal nano-rib over a silicon-on-insulator (SOI) structure. An extremely small mode area of~10???² is achieved together with several microns long propagation distance at the telecom wavelength of 1.55 ?m. The figure of merit (FoM) is also improved in the same time, compared to the pervious hybrid plasmonic waveguide. We demonstrate the validity of our method by comparing our simulating results with some analytical results for a metal cylindrical waveguide and a metal slab waveguide in a wide wavelength range. For the HPW, we find that the nonlocal effects can give less loss and better confinement. In particular, we explore the influence of the radius of the rib's tip on the loss and the confinement. We show that the nonlocal effects give some new fundamental limitation on the confinement, leaving the mode area finite even for geometries with infinitely sharp tips. PMID:23389124

Huang, Qiangsheng; Bao, Fanglin; He, Sailing

2013-01-28

265

Emerging Functionality in Complex Oxides Driven by Spatial Confinement  

NASA Astrophysics Data System (ADS)

The exotic properties displayed by correlated electronic materials (CEMs) such as the cuprates, manganites, ruthenates, Fe-based pnictides, and heavy-fermion compounds are intimately related to the coexistence of competing nearly degenerate states which couple simultaneously active degrees of freedom--charge, lattice, orbital, and spin states. The striking phenomenon in these materials is due in large part to spatial electronic inhomogeneities, or nanoscale phase separation. The functionality in these CEMs is almost always associated with a phase transition, metal-to-insulator, magnetic-to-nonmagnetic, normal metal to superconductor, etc. Spatial confinement on the length scale of the inherent phase separation can probe the basic physics and reveal new emergent behavior. Several examples of the manifestation of spatial confinement will be discussed [1,2], focusing on the observed fluctuations between the competing phases [2]. Work done in collaboration with Jian Shen and Zac Ward at ORNL. [4pt] [1] T. Z. Ward, S. H. Liang, K. Fuchigami, L. F. Yin, E. Daggotto, E. W. Plummer, and J. Shen, ``Reemergent Metal-Insulator Transitions in Manganites Exposed with Spatial Confinement,'' Phys. Rev. Lett. 100, 247204 (2008)[0pt] [2] T. Z. Ward, X. G. Zhang, L. F. Yin, X. Q. Zhang, Ming Liu, P. C. Snijders, S. Jesse, E. W. Plummer, Z. H. Cheng, and J. Shen, ``Time-Resolved Electronic Phase Transitions in Manganites,'' Phys. Rev. Letters, 102, 087201 (2009).

Plummer, Ward

2010-03-01

266

Characteristics of high-confinement modes in Alcator C Mod  

SciTech Connect

The regime of high particle and energy confinement known as the H mode [Phys. Rev. Lett. {bold 49}, 1408 (1982)] has been extended to a unique range of operation for divertor tokamaks up to toroidal fields of nearly 8 T, line-averaged electron densities of 3{times}10{sup 20} m{sup {minus}3}, and surface power densities of nearly 0.6 MW/m{sup 2} in the compact high-field tokamak Alcator C Mod [Phys. Plasmas {bold 1}, 1511 (1994)]. H modes are achieved in Alcator C Mod with Ion Cyclotron Resonant Frequency (ICRF) heating and with Ohmic heating alone without boronization of the all molybdenum tiled first wall. Large increases in charge exchange flux are observed during the H mode over the entire range of energies from 2 to 10 keV. There appears to be an upper limit to the midplane neutral pressure, of about 0.08 Pa above which no H modes have been observed. The plasmas with the best energy confinement have the lowest midplane neutral pressures, below 0.01 Pa. There is an edge electron temperature threshold such that {ital T}{sub {ital e}}{ge}280 eV {plus_minus}40 eV for sustaining the H mode, which is equal at L{endash}H and H{endash}L transitions. The hysteresis in the threshold power between L{endash}H and H{endash}L transitions is less than 25{percent} on average. Both core and edge particle confinement improve by a factor of 2{endash}4 from L mode to H mode. Energy confinement also improves by up to a factor of 2 over L mode. {copyright} {ital 1996 American Institute of Physics.}

Snipes, J.A.; Boivin, R.L.; Christensen, C.; Fiore, C.; Garnier, D.; Goetz, J.; Golovato, S.N.; Graf, M.; Granetz, R.S.; Greenwald, M.; Hubbard, A.; Hutchinson, I.H.; Irby, J.; LaBombard, B.; Marmar, E.S.; Niemczewski, A.; OShea, P.; Porkolab, M.; Stek, P.; Takase, Y.; Terry, J.L.; Umansky, M.; Wolfe, S.M. [Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)] [Plasma Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

1996-05-01

267

Confinement induced binding of noble gas atoms  

NASA Astrophysics Data System (ADS)

The stability of Ngn@B12N12 and Ngn@B16N16 systems is assessed through a density functional study and ab initio simulation. Although they are found to be thermodynamically unstable with respect to the dissociation of individual Ng atoms and parent cages, ab initio simulation reveals that except Ne2@B12N12 they are kinetically stable to retain their structures intact throughout the simulation time (500 fs) at 298 K. The Ne2@B12N12 cage dissociates and the Ne atoms get separated as the simulation proceeds at this temperature but at a lower temperature (77 K) it is also found to be kinetically stable. He-He unit undergoes translation, rotation and vibration inside the cavity of B12N12 and B16N16 cages. Electron density analysis shows that the He-He interaction in He2@B16N16 is of closed-shell type whereas for the same in He2@B12N12 there may have some degree of covalent character. In few cases, especially for the heavier Ng atoms, the Ng-N/B bonds are also found to have some degree of covalent character. But the Wiberg bond indices show zero bond order in He-He bond and very low bond order in cases of Ng-N/B bonds. The energy decomposition analysis further shows that the ?Eorb term contributes 40.9% and 37.3% towards the total attraction in the He2 dimers having the same distances as in He2@B12N12 and He2@B16N16, respectively. Therefore, confinement causes some type of orbital interaction between two He atoms, which akins to some degree of covalent character.

Khatua, Munmun; Pan, Sudip; Chattaraj, Pratim K.

2014-04-01

268

Subwavelength metallic waveguides as a tool for extreme confinement of THz surface waves  

PubMed Central

Research on surface waves supported by metals at THz frequencies is experiencing a tremendous growth due to their potential for imaging, biological sensing and high-speed electronic circuits. Harnessing their properties is, however, challenging because these waves are typically poorly confined and weakly bound to the metal surface. Many design strategies have been introduced to overcome these limitations and achieve increased modal confinement, including patterned surfaces, coated waveguides and a variety of sub-wavelength geometries. Here we provide evidence, using a combination of numerical simulations and time-resolved experiments, that shrinking the transverse size of a generic metallic structure always leads to solutions with extreme field confinement. The existence of such a general behavior offers a new perspective on energy confinement and should benefit future developments in THz science and technology.

Gacemi, D.; Mangeney, J.; Colombelli, R.; Degiron, A.

2013-01-01

269

Effect of confinement on failure in 95 TATB/5 KEL-F  

SciTech Connect

A modification of the usual wedge test for measuring the failure thickness has been developed that eliminates the effect of the confinement provided by the witness plate. The new test uses a prism of the explosive with a line initiator to start a detonation along the trapezoidal face of the prism. Experiments using PBX 9502 have shown that the failure thickness measured using the prism test is 1/2 the failure diameter measured in long cyclindrical charges, provided the wave can propagate 15 to 25 times the failure width. No significant effects of confinement is observed for low impedance confinement, whereas high impedance materials reduce the failure thickness. Thin layers of confinement reduce the failure thickness significantly. Copper, 0.025 mm thick, and 0.25-mm aluminum each reduce the failure thickness of PBX 9502 by 35%. 6 refs., 7 figs.

Ramsay, J.B.

1985-01-01

270

Progress in toroidal confinement and fusion research  

SciTech Connect

During the past 30 years, the characteristic T/sub i/n tau/sub E/-value of toroidal-confinement experiments has advanced by more than seven orders of magnitude. Part of this advance has been due to an increase of gross machine parameters. Most of this advance has been due to an increase of gross machine parameters. Most of the advance is associated with improvements in the ''quality of plasma confinement.'' The combined evidence of spherator and tokamak research clarifies the role of magnetic-field geometry in determining confinement and points to the importance of shielding out plasma edge effects. A true physical understanding of anomalous transport remains to be achieved. 39 refs., 11 figs., 1 tab.

Furth, H.P.

1987-10-01

271

Buckling and layering transitions in confined colloids  

NASA Astrophysics Data System (ADS)

We report layering transitions within a charged silica colloidal dispersion confined by two opposite like-charged dielectric walls. The ensemble-averaged concentration profiles of the colloids (radius 60±2 nm) along the confinement direction have been determined using synchrotron X-ray diffraction from microfluidic arrays of channels of different widths. For small channel widths up to a critical value of 300 nm, the channel can accommodate just one layer of colloids which is stabilized against buckling by the confining charged walls. For channel widths larger than this critical value, a buckling of the single layer is observed. These phenomena are explained using a theoretical analysis of buckling instabilities due to Chou and Nelson, and a value for the charge density on the stabilizing charged walls is derived. At still larger channel widths a sequence of complex layering transitions is observed which involve the splitting and merging of individual layers.

Satapathy, D. K.; Nygård, K.; Bunk, O.; Jefimovs, K.; Perret, E.; Diaz, A.; Pfeiffer, F.; David, C.; van der Veen, J. F.

2009-08-01

272

Neutron Assay System for Confinement Vessel Disposition  

SciTech Connect

Los Alamos National Laboratory has a number of spherical confinement vessels (CVs) remaining from tests involving nuclear materials. These vessels have an inner diameter of 6 feet with 1-inch thick steel walls. The goal of the Confinement Vessel Disposition (CVD) project is to remove debris and reduce contamination inside the CVs. The Confinement Vessel Assay System (CVAS) was developed to measure the amount of special nuclear material (SNM) in CVs before and after cleanout. Prior to cleanout, the system will be used to perform a verification measurement of each vessel. After cleanout, the system will be used to perform safeguards-quality assays of {le}100-g {sup 239}Pu equivalent in a vessel for safeguards termination. The CVAS has been tested and calibrated in preparation for verification and safeguards measurements.

Frame, Katherine C. [Los Alamos National Laboratory; Bourne, Mark M. [Los Alamos National Laboratory; Crooks, William J. [Los Alamos National Laboratory; Evans, Louise [Los Alamos National Laboratory; Mayo, Douglas R. [Los Alamos National Laboratory; Miko, David K. [Los Alamos National Laboratory; Salazar, William R. [Los Alamos National Laboratory; Stange, Sy [Los Alamos National Laboratory; Valdez, Jose I. [Los Alamos National Laboratory; Vigil, Georgiana M. [Los Alamos National Laboratory

2012-07-13

273

Electronic confinement in modulation doped quantum dots  

NASA Astrophysics Data System (ADS)

Modulation doping, an effective way to dope quantum dots (QDs), modifies the confinement energy levels in the QDs. We present a self-consistent full multi-grid solver to analyze the effect of modulation doping on the confinement energy levels in large-area structures containing Si QDs in SiO2 and Si3N4 dielectrics. The confinement energy was found to be significantly lower when QDs were in close proximity to dopant ions in the dielectric. This effect was found to be smaller in Si3N4, while smaller QDs in SiO2 were highly susceptible to energy reduction. The energy reduction was found to follow a power law relationship with the QD size.

Puthen Veettil, B.; König, D.; Patterson, R.; Smyth, S.; Conibeer, G.

2014-04-01

274

Electron plasmas: Confinement and mode structure in a small aspect ratio toroidal experiment  

NASA Astrophysics Data System (ADS)

Toroidal electron plasmas have remained less explored due to their poor confinement properties. Their equilibrium, stability, and confinement properties are therefore not entirely understood and continue to remain a topic of intense ongoing research. Large aspect-ratio theory suggests poor confinement in toroidal devices can be overcome by the application of a radial electric field; this has been verified successfully in some of the recent experiments. In the present paper, we report the longest confinement time without these external forces. Increasing the toroidicity has helped us to generate these forces intrinsically. To this end, a trap to confine electron plasmas has been created in a small aspect-ratio (~1.6) torus. Electrons after being injected from a thermionic source are seen to remain confined with a purely toroidal magnetic field. The confinement time is far more than known single particle drift time scales. Importantly, it is in the absence of any external electric field, additional rotational transform, and/or magnetic fields, which, although not required, in principle, may appear essential particularly due to their role in improving confinement in some of the recent large aspect-ratio traps. The successful confinement in the small aspect-ratio limit has also led to several interesting observations: the evolution of the confined plasma is marked by an interesting nonlinear (large amplitude), electrostatic wave activity. Coherent, periodic, double peak oscillations result from a low-frequency E×B motion of a toroidal vortex in a plasma that closely leans against the inner wall. As many as 16 highly phase-coherent harmonics with dominant power in m=2 suggest that the mode is not merely a center-of-charge motion. Rather, a strong coupling of modes leads to a novel nonlinear state. The predominant energy is present in the shaping of the electron cloud (m=2) and not in the displacement of the center of charge (m=1) seen in large aspect-ratio traps. The absence of any power-law tail suggests absence of any turbulence, at least on time scales longer than the wall-probe resolution (40 ns). The frequency, (around 100 kHz at 200 G) shows an unusual shear in time: it reduces as the mode evolves, but later increases as the mode dies.

Pahari, S.; Ramachandran, H. S.; John, P. I.

2006-09-01

275

Charge transport in confined ionic liquids  

NASA Astrophysics Data System (ADS)

Charge transport and glassy dynamics in neat and polymerized ionic liquids confined in nanoporous silica are investigated in a wide frequency and temperature ranges by a combination of Broadband Dielectric Spectroscopy and Pulsed Field Gradient Nuclear Magnetic Resonance (PFG NMR). By applying the Einstein-Smoluchowski relations to the dielectric spectra, diffusion coefficients are obtained in quantitative agreement with independent PFG NMR. The impact of geometrical confinement as well as the pore wall-ionic liquid interactions on the overall ionic mobility is explored for diverse categories of ionic liquids. The results are discussed within the framework of dynamic glass transition assisted charge transport in ionic liquids.

Sangoro, Joshua; Iacob, Ciprian; Kipnusu, Wycliffe; Kremer, Friedrich

2011-03-01

276

Neutral Beam Ion Confinement in NSTX  

SciTech Connect

Neutral-beam (NB) heating in the National Spherical Torus Experiment (NSTX) began in September 2000 using up to 5 MW of 80 keV deuterium (D) beams. An initial assessment of beam ion confinement has been made using neutron detectors, a neutral particle analyzer (NPA), and a Faraday cup beam ion loss probe. Preliminary neutron results indicate that confinement may be roughly classical in quiescent discharges, but the probe measurements do not match a classical loss model. MHD activity, especially reconnection events (REs) causes substantial disturbance of the beam ion population.

D.S. Darrow; E.D. Fredrickson; S.M. Kaye; S.S. Medley; and A.L. Roquemore

2001-07-24

277

New confinement phases from singular SCFT  

NASA Astrophysics Data System (ADS)

New types of confining phase emerge when some singular SCFT's appearing as infrared fixed points of {N}=2 supersymmetric QCD (SQCD) are deformed by an {N}=1 adjoint mass term. We make further checks on the Gaiotto-Seiberg-Tachikawa (GST) description of these vacua against the symmetry and vacuum counting argument, and show that the GST variables correctly describe these systems, brought into confinement phase by the {N}=1 perturbation. Several examples of such vacua, USp(2 N) and SU( N) theories with four flavors and SO( N) theories with one or two flavors, are discussed.

Giacomelli, Simone; Konishi, Kenichi

2013-03-01

278

Confinement improvement by fluctuating input power  

NASA Astrophysics Data System (ADS)

An interesting effect of the fluctuating input power on plasma confinement is reported. Specifically, the addition of the sinusoidal perturbation, Asin(wt), to constant power q0 is shown to promote the confinement, leading to the L-H transition at a lower value of q0, as compared to the case of constant q0 without the sinusoidal perturbation. In general, higher amplitude (A) and lower frequency (w) are found to be more favorable for the L-H transition while an interesting linear relation between A and w leading to the L-H transition is established for different values of q0.

Douglas, Sarah; Mohamed, Mabruka; Kim, Eun-jin

2013-11-01

279

Supersymmetric confining model of the weak interactions  

SciTech Connect

We present a supersymmetric, confining model of the weak interactions based on the gauge group SU (M)/sub S//sub C/ x SU(2)/sub L/ x SU(3)/sub C/ x U(1) (SC denotes supercolor). Supersymmetry protects chiral symmetries from spontaneous breakdown and allows a solution to the strong CP problem. There are interesting consequences for supersymmetry and R-invariance breaking. The maximum number of lepton and quark families in supersymmetric confining models is shown to be N/sub F/ = 3.

Ng, Y.J.; Ovrut, B.A.

1984-01-01

280

Numerical analysis of seismoelectromagnetic field conversion at confined geological units  

NASA Astrophysics Data System (ADS)

It is well known that at material boundaries in fluid-saturated porous media, an incoming seismic wave can give rise to electric and magnetic fields due to electrokinetic coupling effects. Given its sensitivity to rock parameters governing fluid flow, this so-called seismoelectromagnetic (or seismoelectric, if only the electric field is considered) interface response is of strong interest with a view to hydro geophysical and petroleum exploration applications. However, the understanding of the correspondence of the converting interface geometry on the one hand and electric and magnetic field characteristics on the other hand is still poor. By means of two-dimensional finite-element modeling in the time domain, we here investigate the character of the seismoelectromagnetic interface response for the special case of spatially confined geological units, which may be representative for clay lenses embedded in an aquifer or petroleum deposits in a host rock. In the numerical analysis we consider the interface response generated by both compressional and shear wave. The modeling results, which are analyzed in terms of snapshots, time slices, and electro and magneto grams, reveal a significant influence of the confined geological units on the generation and character of the seismoelectro-magnetic interface response. The different conversion patterns can be attributed to the induced streaming currents at the interfaces caused by the oscillation of the seismic body waves. Pattern analysis of the interface responses is done with a view to an improved qualitative understanding of their spatio-temporal occurrence and evolution relative to the geometry of the converting interfaces. Our time-lapse simulations illustrate that the seismoelectromagnetic interface response captures characteristics of the geometry of the converting geological unit, indicating the potential of the seismoelectromagnetic method in particular for exploration of confined targets.

Kroeger, B.; Kemna, A.

2010-12-01

281

Inertial-confinement-fusion targets  

SciTech Connect

Much of the research in laser fusion has been done using simple ball on-stalk targets filled with a deuterium-tritium mixture. The targets operated in the exploding pusher mode in which the laser energy was delivered in a very short time (approx. 100 ps or less) and was absorbed by the glass wall of the target. The high energy density in the glass literally exploded the shell with the inward moving glass compressing the DT fuel to high temperatures and moderate densities. Temperatures achieved were high enough to produce DT reactions and accompanying thermonuclear neutrons and alpha particles. The primary criteria imposed on the target builders were: (1) wall thickness, (2) sphere diameter, and (3) fuel in the sphere.

Hendricks, C.D.

1982-08-10

282

Coulomb Energy, Vortices, and Confinement  

SciTech Connect

d on 25 Feb 2003 (v1), last revised 10 Apr 2003 (this version, v2))We estimate the Coulomb energy of static quarks from a Monte Carlo calculation of the correlator of timelike link variables in Coulomb gauge. We find, in agreement with Cucchieri and Zwanziger, that this energy grows linearly with distance at large quark separations. The corresponding string tension, however, is several times greater than the accepted asymptotic string tension, indicating that a state containing only static sources, with no constituent gluons, is not the lowest energy flux tube state. The Coulomb energy is also measured on thermalized lattices with center vortices removed by the de Forcrand-D'Elia procedure. We find that when vortices are removed, the Coulomb string tension vanishes.

Greensite, J.; Olejnik, S.

2003-02-25

283

Drift-diffusion kinetics of a confined colloid  

NASA Astrophysics Data System (ADS)

The drift-diffusion equation on a finite interval with reflecting boundary conditions is solved by Laplace transformation. The Green function is obtained as a series in powers of e - hu/D, where u is the drift velocity, D the diffusion coefficient and h the width of the interval. In the drift-dominated regime hu/D\\gg 1 , the first terms provide an exact solution in the limit of short and long times, and a good approximation in the intermediate regime. As a possible application, we discuss confined colloidal suspensions subjected to an external field.

Leroyer, Yves; Würger, Alois

2010-05-01

284

High-performance inertial confinement fusion target implosions on OMEGA  

NASA Astrophysics Data System (ADS)

The Omega Laser Facility is used to study inertial confinement fusion (ICF) concepts. This paper describes progress in direct-drive central hot-spot (CHS) ICF, shock ignition (SI) and fast ignition (FI) since the 2008 IAEA FEC conference. CHS cryogenic deuterium-tritium (DT) target implosions on OMEGA have produced the highest DT areal densities yet measured in ICF implosions (~300 mg cm-2). Integrated FI experiments have shown a significant increase in neutron yield caused by an appropriately timed high-intensity, high-energy laser pulse.

Meyerhofer, D. D.; McCrory, R. L.; Betti, R.; Boehly, T. R.; Casey, D. T.; Collins, T. J. B.; Craxton, R. S.; Delettrez, J. A.; Edgell, D. H.; Epstein, R.; Fletcher, K. A.; Frenje, J. A.; Glebov, Y. Yu.; Goncharov, V. N.; Harding, D. R.; Hu, S. X.; Igumenshchev, I. V.; Knauer, J. P.; Li, C. K.; Marozas, J. A.; Marshall, F. J.; McKenty, P. W.; Nilson, P. M.; Padalino, S. P.; Petrasso, R. D.; Radha, P. B.; Regan, S. P.; Sangster, T. C.; Séguin, F. H.; Seka, W.; Short, R. W.; Shvarts, D.; Skupsky, S.; Soures, J. M.; Stoeckl, C.; Theobald, W.; Yaakobi, B.

2011-05-01

285

Drift-diffusion kinetics of a confined colloid.  

PubMed

The drift-diffusion equation on a finite interval with reflecting boundary conditions is solved by Laplace transformation. The Green function is obtained as a series in powers of e(-hu/D), where u is the drift velocity, D the diffusion coefficient and h the width of the interval. In the drift-dominated regime hu/D > 1, the first terms provide an exact solution in the limit of short and long times, and a good approximation in the intermediate regime. As a possible application, we discuss confined colloidal suspensions subjected to an external field. PMID:21386448

Leroyer, Yves; Würger, Alois

2010-05-19

286

A molecular dynamics study of freezing in a confined geometry  

NASA Technical Reports Server (NTRS)

The dynamics of freezing of a Lennard-Jones liquid in narrow channels bounded by molecular walls is studied by computer simulation. The time development of ordering is quantified and a novel freezing mechanism is observed. The liquid forms layers and subsequent in-plane ordering within a layer is accompanied by a sharpening of the layer in the transverse direction. The effects of channel size, the methods of quench, the liquid-wall interaction and the roughness of walls on the freezing mechanism are elucidated. Comparison with recent experiments on freezing in confined geometries is presented.

Ma, Wen-Jong; Banavar, Jayanth R.; Koplik, Joel

1992-01-01

287

Magnetospheric Vortex Formation: Self-Organized Confinement of Charged Particles  

SciTech Connect

A magnetospheric configuration gives rise to various peculiar plasma phenomena that pose conundrums to astrophysical studies; at the same time, innovative technologies may draw on the rich physics of magnetospheric plasmas. We have created a ''laboratory magnetosphere'' with a levitating superconducting ring magnet. Here we show that charged particles (electrons) self-organize a stable vortex, in which particles diffuse inward to steepen the density gradient. The rotating electron cloud is sustained for more than 300 s. Because of its simple geometry and self-organization, this system will have wide applications in confining single- and multispecies charged particles.

Yoshida, Z.; Saitoh, H.; Morikawa, J.; Yano, Y.; Watanabe, S.; Ogawa, Y. [Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba 277-8561 (Japan)

2010-06-11

288

Magnetospheric vortex formation: self-organized confinement of charged particles.  

PubMed

A magnetospheric configuration gives rise to various peculiar plasma phenomena that pose conundrums to astrophysical studies; at the same time, innovative technologies may draw on the rich physics of magnetospheric plasmas. We have created a "laboratory magnetosphere" with a levitating superconducting ring magnet. Here we show that charged particles (electrons) self-organize a stable vortex, in which particles diffuse inward to steepen the density gradient. The rotating electron cloud is sustained for more than 300 s. Because of its simple geometry and self-organization, this system will have wide applications in confining single- and multispecies charged particles. PMID:20867249

Yoshida, Z; Saitoh, H; Morikawa, J; Yano, Y; Watanabe, S; Ogawa, Y

2010-06-11

289

Anomalous diffusion in confined monolayer films  

Microsoft Academic Search

A monolayer, solid, epitaxial film confined to a prototypal slit-pore (a monatomic substance constrained between two parallel planar walls of like atoms) and subjected to a shear strain (created by altering the transverse lateral alignment of the walls) begins to melt if a critical strain (shear melting point) is exceeded. The resulting 'molten' phase exhibits structural disorder characteristic of a

Martin Schoen; John H. Cushman; Dennis J. Diestler

1994-01-01

290

Anomalous diffusion in confined monolayer films  

Microsoft Academic Search

A monolayer, solid, epitaxial film confined to a prototypal slit-pore (a monatomic substance constrained between two parallel planar walls of like atoms) and subjected to a shear strain (created by altering the transverse lateral alignment of the walls) begins to melt if a critical strain (shear melting point) is exceeded. The resulting ‘molten’ phase exhibits structural disorder characteristic of a

Martin Schoen; John H. Cushman; Dennis J. Diestler

1994-01-01

291

Hohlraum manufacture for inertial confinement fusion  

SciTech Connect

Hohlraums are an integral part of indirect drive targets for Inertial Confinement Fusion (ICF) research. Hohlraums are made by an electroforming process that combines elements of micromachining and coating technology. The authors describe how these target element are made and extension of the method that allow fabrication of other, more complex target components.

Foreman, L.R.; Gobby, P.; Bartos, J. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.] [and others

1994-07-01

292

Energy confinement in turbulent fluid plasmas  

SciTech Connect

Scaling laws for energy confinement in a turbulent plasma dominated by resistive pressure-driven modes are revisited. New scaling laws are obtained under a consistent low-beta approximation, and differ from earlier theories primarily in their dependence on the plasma pressure.

Bhattacharjee, A.; Hameiri, E.

1988-05-01

293

Inertial confinement fusion with light ion beams  

Microsoft Academic Search

The Particle Beam Fusion Accelerator II (PBFA II) is presently under construction and is the only existing facility with the potential of igniting thermonuclear fuel in the laboratory. The accelerator will generate up to 5 megamperes of lithium ions at 30 million electron volts and will focus them onto an inertial confinement fusion (ICF) target after beam production and focusing

J. P. VanDevender; D. L. Cook

1986-01-01

294

Radioactivity Confinement Studies Within the SEAL Program  

Microsoft Academic Search

In the framework of the European SEAL program, investigations have been performed with the aim of optimizing the second confinement function and plant layout with respect to normal operation as well as abnormal operation, including accident conditions. This has been done for two conceptual fusion reactor designs: one using water as the coolant and the other using helium. The starting

Jan Collén; Ron Matsugu; Antonio Natalizio; Kecheng Shen

1997-01-01

295

Spontaneous abortion and confined chromosomal mosaicism  

Microsoft Academic Search

Confined placental chorionic mosaicism is reported in 2% of viable pregnancies cytogenetically analyzed on chorionic villi samplings (CVS) at 9–12 weeks of gestation. In follow-up studies this mosaicism has been shown to be associated with increased frequency of second and third trimester pregnancy loss or intrauterine fetal growth retardation. We have studied 54 spontaneous abortions (SA) for the detection of

Dagmar K. Kalousek; Irene J. Barrette; Antia B. Gärtner

1992-01-01

296

Turbulence modelling of confined swirling flows.  

National Technical Information Service (NTIS)

Five test cases including a parallel and four confined swirling flows are calculated by means of the computer code FLOW3D from Harwell Laboratory. The k-(epsilon) model (KEM) and Reynolds stress model RSM are used to calculate isothermal flows, but to cal...

Chinh Minh Trinh

1993-01-01

297

Chirally symmetric but confining dense, cold matter  

SciTech Connect

The folklore tradition about the QCD phase diagram is that at the chiral restoration phase transition at finite density hadrons are deconfined and there appears the quark matter. We address this question within the only known exactly solvable confining and chirally symmetric model. It is postulated within this model that there exists linear Coulomb-like confining interaction. The chiral symmetry breaking and the quark Green function are obtained from the Schwinger-Dyson (gap) equation while the color-singlet meson spectrum results from the Bethe-Salpeter equation. We solve this model at T=0 and finite chemical potential {mu} and obtain a clear chiral restoration phase transition at the critical value {mu}{sub cr}. Below this value the spectrum is similar to the previously obtained one at {mu}=0. At {mu}>{mu}{sub cr} the quarks are still confined and the physical spectrum consists of bound states which are arranged into a complete set of exact chiral multiplets. This explicitly demonstrates that a chirally symmetric matter consisting of confined but chirally symmetric hadrons at finite chemical potential is also possible in QCD. If so, there must be nontrivial implications for astrophysics.

Glozman, L. Ya.; Wagenbrunn, R. F. [Institute for Physics, Theoretical Physics Branch, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria)

2008-03-01

298

Thermal performance measurement for confined heat sinks  

Microsoft Academic Search

The convective heat transfer characteristics for confined heat sinks by using two experimental methods such as the improved transient liquid crystal method and thermal testing method have been systematically investigated. The trends of average effective heat transfer coefficients measured by using transient liquid crystal method are consistent with that by using thermal testing method. The deviation of the results evaluated

T. S. Chai; J. T. Horng; T. Y. Wu; Y. H. Hung

2004-01-01

299

Elastic wave propagation in confined granular systems  

Microsoft Academic Search

We present numerical simulations of acoustic wave propagation in confined granular systems consisting of particles interacting with the three-dimensional Hertz-Mindlin force law. The response to a short mechanical excitation on one side of the system is found to be a propagating coherent wave front followed by random oscillations made of multiply scattered waves. We find that the coherent wave front

Ellák Somfai; Jean-Noël Roux; Jacco H. Snoeijer; Martin van Hecke; Wim van Saarloos

2005-01-01

300

Study of Superfluid He Under Nanoscale Confinement  

NASA Astrophysics Data System (ADS)

We review recent experiments in which superfluid He has been studied under highly controlled confinement in nanofluidic sample chambers. We discuss the experimental challenges and their resolution. These methods open the way to a systematic investigation of the superfluidity of He films, and the surface and edge excitations of topological superfluids.

Levitin, L. V.; Bennett, R. G.; Casey, A.; Cowan, B.; Saunders, J.; Drung, D.; Schurig, Th.; Parpia, J. M.; Ilic, B.; Zhelev, N.

2014-06-01

301

Probing cell traction forces in confined microenvironments.  

PubMed

Cells migrate in vivo within three-dimensional (3D) extracellular matrices. Cells also migrate through 3D longitudinal channels formed between the connective tissue and the basement membrane of muscle, nerve, and epithelium. Although traction forces have been measured during 2D cell migration, no assay has been developed to probe forces during migration through confined microenvironments. We thus fabricated a novel microfluidic device consisting of deflectable PDMS microposts incorporated within microchannels of varying cross-sectional areas. Using NIH-3T3 fibroblasts and human osteosarcoma (HOS) cells as models, we found that the average traction forces per post decreased upon increasing confinement. Inhibition of myosin-II function by blebbistatin in HOS cells decreased traction forces in unconfined (wide) channels but failed to alter them in confined spaces. Myosin activation by calyculin A also failed to affect traction forces in confining channels but increased them in wide channels. These observations underlie the importance of the physical microenvironment in the regulation of cell migration and cellular traction forces. PMID:24100608

Raman, Phrabha S; Paul, Colin D; Stroka, Kimberly M; Konstantopoulos, Konstantinos

2013-12-01

302

Contributions on Laser Driven Inertial Confinement Fusion  

Microsoft Academic Search

The following modified preprint of a chapter in the forthcoming book by Guillermo Velarde and Natividad Carpintero Santamaria Inertial Confinement Nuclear Fusion: A Historical Approach by its Pioneers with personal comments is presented here as an example about the long years difficult developments towards the aim for producing unlimited, safe and clean nuclear energy in the same way as it

Heinrich Hora

303

Beam optics in inertial electrostatic confinement fusion  

Microsoft Academic Search

We study the transport of ions and electrons near the cathode of the inertial electrostatic confinement fusion that is expected to be a portable neutron source. We carry out a PIC particle simulation in order to obtain the self-consistent electrostatic potential and the transparency of the cathode for the accelerated ions. The transparency is shown to be much less than

Masami Ohnishi; Chikara Hoshino; Kiyoshi Yoshikawa; Kai Masuda; Yasushi Yamamoto

2000-01-01

304

Inertial electrostatic confinement for fusion applications  

Microsoft Academic Search

Inertial electrostatic confinement (IEC) devices have demonstrated significant neutron yields (as high as 2×1010 neutrons\\/second, steady state) in a compact and inexpensive scale. Recent technological progress in plasma sources, vacuum technology and high voltage materials indicates that an order of magnitude increase in neutron yield may be achievable within a few years.

R. A. Nebel; C. P. Munson; W. G. Rellergert; M. D. Sekora

2003-01-01

305

Negative ions in inertial electrostatic confinement devices  

Microsoft Academic Search

The UW-Inertial Electrostatic Confinement (IEC) device is comprised of concentric, nearly transparent, spherical metallic grids within a cylindrical vacuum vessel. The central grid, which can be held at high negative potentials (~ -100 to -200 kV) is the device cathode, while the outer grid, held at ground potential, is the device anode. This configuration accelerates ions, created near the anode,

D. R. Boris; J. F. Santarius; G. L. Kulcinski

2009-01-01

306

Nuclear diagnostics for inertial confinement fusion implosions  

SciTech Connect

This abstract contains viewgraphs on nuclear diagnostic techniques for inertial confinement fusion implosions. The viewgraphs contain information on: reactions of interest in ICF; advantages and disadvantages of these methods; the properties nuclear techniques can measure; and some specifics on the detectors used.

Murphy, T.J.

1997-11-01

307

Confined Lennard-Jones System Model  

NSDL National Science Digital Library

The Confined Lennard-Jones System is an idealized statistical mechanics model that simulates a two-dimensional system of particles confined to a box with a constant temperature thermal reservoir at one end and a movable piston at the other. Particles in this model have unit mass and interact through pairwise Lennard-Jones forces and hard-wall contact forces. Slow-moving particles are color-coded as blue and fast particles are color-coded as yellow. The model computes and plots the evolution of the total energy E, the kinetic energy per particle K, the pressure P, and the volume V. The model also displays histograms and mean values of these quantities. The Confined Lennard-Jones System was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_stp_md_ConfinedLennardJonesSystem.jar file will run the program if Java is installed.

Christian, Wolfgang

2010-12-27

308

Confinement Chamber for Radioactive Products or Waste.  

National Technical Information Service (NTIS)

The invention deals with a confinement chamber for radioactive products or wastes that are kept in tanks or in silos buried in the ground. The chamber comprises a combination of an impervious reinforced concrete (RC) support buried in the ground with an R...

1977-01-01

309

Instability of confined rings: an experimental approach  

Microsoft Academic Search

The stability of a ring confined by a rigid boundary, subjected to circumferential end loads is investigated by an experimental approach. Dimensional analysis was used to establish the basic relationship of the critical buckling stress with material properties, geometric dimensions and initial geometric imperfections. The coefficients in the relationship were obtained experimentally. Compared to other theoretical methods, this approach is

C. Sun; W. J. D. Shaw; A. M. Vinogradov

1995-01-01

310

Inertial confinement fusion neutron images  

SciTech Connect

At the OMEGA laser facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)], 14-MeV neutron images are acquired with a 20-{mu}m resolution and a large signal-to-noise ratio (SNR) using penumbral and ring apertures. The two aperture types produce coded images of the source that are unfolded using a similar autocorrelation method. The techniques provide comparable images for various deuterium-tritium filled target implosions, with glass and plastic (CH) shells. SNR analysis reveals that the annular (ring) technique will achieve a good image quality at the 10-{mu}m resolution level with the planned upgrade of our novel detector. The detector is an array of 85-{mu}m-diam capillary tubes filled with a liquid scintillator. Its resolution is limited to 650 {mu}m by the track length of the elastically scattered recoil protons. Replacing the hydrogen in the scintillator with deuterium improves detector spatial resolution to 325 {mu}m, and makes high source resolution achievable. The readout design provides an efficient light collection of the scintillation photons by relaying the image through a fiber optic taper. Improved efficiency produces images with better SNR. Also, the increased detector sensitivity allows single event recording of 2.45-MeV neutron interactions. For the first time ever, we show neutron images of deuterium filled, warm, and cryogenic target implosions.

Disdier, L.; Rouyer, A.; Lantuejoul, I.; Landoas, O.; Bourgade, J.L.; Sangster, T.C.; Glebov, V.Yu.; Lerche, R.A. [CEA-DAM Ile de France, BP 12, 91680 Bruyeres Le Chatel (France); Laboratory for Laser Energetics, Rochester, New York 14623-1299 (United States); Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

2006-05-15

311

JET confinement studies and their scaling to high ?N, ITER scenarios  

NASA Astrophysics Data System (ADS)

The ITER hybrid scenario aims to exploit non-inductive current drive to enable burn times in excess of 1000 s. To achieve this, and optimize fusion performance, requires high ?N (the plasma pressure normalized to a stability scaling) and energy confinement equal to or greater than that predicted for the baseline scenario. This paper discusses results from the JET candidate hybrid scenario, where ?N,MHD <= 3.6 plasmas have been produced. Despite a different initial phase, confinement relevant plasma parameters evolve rapidly towards those of equivalent ELMy H-modes and are well described by IPB98(y, 2). In contrast to previous ELMy H-mode studies, a dedicated ? scan experiment in the JET hybrid candidate scenario shows a strong negative dependence of global confinement on ?N. Analysis indicates that the core transport remains consistent with weakly dependent electrostatic transport, whilst the edge confinement decreases strongly with increasing ?N. By combining global confinement data from ASDEX Upgrade, DIII-D and JET hybrid scenario discharges, a multi-machine database is produced. In contrast to the JET case, confinement in ASDEX Upgrade and DIII-D is shown to be inconsistent with IPB98(y, 2) and alternative dependences are explored.

McDonald, D. C.; Laborde, L.; DeBoo, J. C.; Ryter, F.; Brix, M.; Challis, C. D.; de Vries, P.; Giroud, C.; Hobirk, J.; Howell, D.; Joffrin, E.; Luce, T. C.; Mailloux, J.; Pericoli-Ridolfini, V.; Sips, A. C. C.; Thomsen, K.; EFDA Contributors, JET

2008-12-01

312

[Analysis of Cr in soil by LIBS based on conical spatial confinement of plasma].  

PubMed

The present study is to improve the sensitivity of detection and reduce the limit of detection in detecting heavy metal of soil by laser induced breakdown spectroscopy (LIBS). The Cr element of national standard soil was regarded as the research object. In the experiment, a conical cavity with small diameter end of 20 mm and large diameter end of 45 mm respectively was installed below the focusing lens near the experiment sample to mainly confine the signal transmitted by plasma and to some extent to confine the plasma itself in the LIBS setup. In detecting Cr I 425.44 nm, the beast delay time gained from experiment is 1.3 micros, and the relative standard deviation is below 10%. Compared with the setup of non-spatial confinement, the spectral intensity of Cr in the soil sample was enhanced more than 7%. Calibration curve was established in the Cr concentration range from 60 to 400 microg x g(-1). Under the condition of spatial confinement, the liner regression coefficient and the limit of detection were 0.997 71 and 18.85 microg x g(-1) respectively, however, the regression coefficient and the limit of detection were 0.991 22 and 36.99 microg x g(-1) without spatial confinement. So, this shows that conical spatial confinement can/improve the sensitivity of detection and enhance the spectral intensity. And it is a good auxiliary function in detecting Cr in the soil by laser induced breakdown spectroscopy. PMID:24555394

Lin, Yong-Zeng; Yao, Ming-Yin; Chen, Tian-Bing; Li, Wen-Bing; Zheng, Mei-Lan; Xu, Xue-Hong; Tu, Jian-Ping; Liu, Mu-Hua

2013-11-01

313

Characterization of energy confinement in net-current free plasmas using the extended International Stellarator Database  

NASA Astrophysics Data System (ADS)

International collaboration on development of a stellarator confinement database has progressed. More than 3000 data points from nine major stellarator experiments have been compiled. Robust dependences of the energy confinement time on the density and the heating power have been confirmed. Dependences on other operational parameters, i.e. the major and minor radii, magnetic field and the rotational transform \\iobar , have been evaluated using inter-machine analyses. In order to express the energy confinement in a unified scaling law, systematic differences in each subgroup are quantified. An a posteriori approach using a confinement enhancement factor on ISS95 as a renormalizing configuration-dependent parameter yields a new scaling expression ISS04; \\tau _E^ISS04 = 0.134a^{2.28}R^{0.64}P^{ - 0.61}\\bar {n}_{\\rme}^{0.54} B^{0.84}\\iobar_{2 / 3}^{0.41} . Gyro-Bohm characteristic similar to ISS95 has been confirmed for the extended database with a wider range of plasma parameters and magnetic configurations than in the study of ISS95. It has also been discovered that there is a systematic offset of energy confinement between magnetic configurations, and its measure correlates with the effective helical ripple of the external stellarator field. Full documentation of the International Stellarator Confinement Database is available at http://iscdb.nifs.ac.jp/ and http://www.ipp.mpg.de/ISS.

Yamada, H.; Harris, J. H.; Dinklage, A.; Ascasibar, E.; Sano, F.; Okamura, S.; Talmadge, J.; Stroth, U.; Kus, A.; Murakami, S.; Yokoyama, M.; Beidler, C. D.; Tribaldos, V.; Watanabe, K. Y.; Suzuki, Y.

2005-12-01

314

Ultrasonic interferometer for first-sound measurements of confined liquid He4  

NASA Astrophysics Data System (ADS)

We present a new technique for probing the properties of quantum fluids in restricted geometries. We have confined liquid He4 within microfluidic devices formed from glass wafers, in which one dimension is on the micrometer scale. Using an ultrasonic analog to Fabry-Pérot interferometry, we have measured the first sound of the confined liquid He4, which can be a probe of critical behavior near the lambda point (T?). All thermodynamic properties of liquid He4 can be derived from first-sound and heat capacity measurements, and although quite a bit of experimental work has been done on the latter, no measurement of first sound has been reported for a precisely confined geometry smaller than a few tens of micrometers. In this work, we report measurements of isobaric first sound in liquid He4 confined in cavities as small as ˜5 ?m. Our experimental setup allows us to pressurize the liquid up to ˜25 bar without causing deformation of the confined geometry, a pressure which is about four times larger than previously reported with similar microfluidic devices. Our preliminary results indicate that one can possibly observe finite-size effects and verify scaling laws, by using similar devices with smaller confinement.

Rojas, X.; Hauer, B. D.; MacDonald, A. J. R.; Saberi, P.; Yang, Y.; Davis, J. P.

2014-05-01

315

A COMPARATIVE STUDY OF CONFINED AND ERUPTIVE FLARES IN NOAA AR 10720  

SciTech Connect

We investigate the distinct properties of two types of flares: eruptive flares associated with coronal mass ejections (CMEs) and confined flares without CMEs. Our study sample includes nine M- and X-class flares, all from the same active region (AR), six of which are confined and three others which are eruptive. The confined flares tend to be more impulsive in the soft X-ray time profiles and show slenderer shapes in the Extreme-ultraviolet Imaging Telescope 195 A images, while the eruptive ones are long-duration events and show much more extended brightening regions. The location of the confined flares is closer to the center of the AR, while the eruptive flares are at the outskirts. This difference is quantified by the displacement parameter, which is the distance between the AR center and the flare location; the average displacement of the six confined flares is 16 Mm, while that of the eruptive ones is as large as 39 Mm. Further, through nonlinear force-free field extrapolation, we find that the decay index of the transverse magnetic field in the low corona ({approx}10 Mm) is larger for eruptive flares than for confined ones. In addition, the strength of the transverse magnetic field over the eruptive flare sites is weaker than it is over the confined ones. These results demonstrate that the strength and the decay index of the background magnetic field may determine whether or not a flare is eruptive or confined. The implication of these results on CME models is discussed in the context of torus instability of the flux rope.

Cheng, X.; Ding, M. D.; Guo, Y. [Department of Astronomy, Nanjing University, Nanjing 210093 (China); Zhang, J. [School of Physics, Astronomy, and Computational Sciences, George Mason University, 4400 University Drive, MSN 6A2, Fairfax, VA 22030 (United States); Su, J. T., E-mail: dmd@nju.edu.cn [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

2011-05-10

316

Confinement matrices for low- and intermediate-level radioactive waste  

NASA Astrophysics Data System (ADS)

Mining of uranium for nuclear fuel production inevitably leads to the exhaustion of natural uranium resources and an increase in market price of uranium. As an alternative, it is possible to provide nuclear power plants with reprocessed spent nuclear fuel (SNF), which retains 90% of its energy resource. The main obstacle to this solution is related to the formation in the course of the reprocessing of SNF of a large volume of liquid waste, and the necessity to concentrate, solidify, and dispose of this waste. Radioactive waste is classified into three categories: low-, intermediate-, and high-level (LLW, ILW, and HLW); 95, 4.4, and 0.6% of the total waste are LLW, ILW, and HLW, respectively. Despite its small relative volume, the radioactivity of HLW is approximately equal to the combined radioactivity of LLW + ILW (LILW). The main hazard of HLW is related to its extremely high radioactivity, the occurrence of long-living radionuclides, heat release, and the necessity to confine HLW for an effectively unlimited time period. The problems of handling LILW are caused by the enormous volume of such waste. The available technology for LILW confinement is considered, and conclusion is drawn that its concentration, vitrification, and disposal in shallow-seated repositories is a necessary condition of large-scale reprocessing of SNF derived from VVER-1000 reactors. The significantly reduced volume of the vitrified LILW and its very low dissolution rate at low temperatures makes borosilicate glass an ideal confinement matrix for immobilization of LILW. At the same time, the high corrosion rate of the glass matrix at elevated temperatures casts doubt on its efficient use for immobilization of heat-releasing HLW. The higher cost of LILW vitrification compared to cementation and bitumen impregnation is compensated for by reduced expenditure for construction of additional engineering barriers, as well as by substantial decrease in LLW and ILW volume, localization of shallow-seated repositories in various geological media, and the use of inexpensive borosilicate glass.

Laverov, N. P.; Omel'Yanenko, B. I.; Yudintsev, S. V.; Stefanovsky, S. V.

2012-02-01

317

The Evaporation Regime in a Confined Flare  

NASA Astrophysics Data System (ADS)

We studied the evolution of a small eruptive flare (GOES class C1) from its onset phase using multi-wavelength observations that sample the flare atmosphere from the chromosphere to the corona. The main instruments involved were the Coronal Diagnostic Spectrometer (CDS) aboard SOHO and facilities at the Dunn Solar Tower of the National Solar Observatory/Sacramento Peak. Transition Region and Coronal Explorer (TRACE) together with Ramaty High-Energy Spectroscopic Imager (RHESSI) also provided images and spectra for this flare. H? and TRACE images display two loop systems that outline the pre-reconnection and post-reconnection magnetic field lines and their topological changes revealing that we are dealing with an eruptive confined flare. RHESSI data do not record any detectable emission at energies ?25 keV, and the observed count spectrum can be well fitted with a thermal plus a non-thermal model of the photon spectrum. A non-thermal electron flux F ? 5 × 1010 erg cm-2 s-1 is determined. The reconstructed images show a very compact source whose peak emission moves along the photospheric magnetic inversion line during the flare. This is probably related to the motion of the reconnection site, hinting at an arcade of small loops that brightens successively. The analysis of the chromospheric spectra (Ca II K, He I D3 and H?, acquired with a four-second temporal cadence) shows the presence of a downward velocity (between 10 and 20 km s-1) in a small region intersected by the spectrograph slit. The region is included in an area that, at the time of the maximum X-ray emission, shows upward motions at transition region (TR) and coronal levels. For the He I 58.4 and O v 62.97 lines, we determine a velocity of ?-40 km s-1 while for the Fe XIX 59.22 line a velocity of ?-80 km s-1 is determined with a two-component fitting. The observations are discussed in the framework of available hydrodynamic simulations and they are consistent with the scenario outlined by Fisher (1989). No explosive evaporation is expected for a non-thermal electron beam of the observed characteristics, and no gentle evaporation is allowed without upward chromospheric motion. It is suggested that the energy of non-thermal electrons can be dissipated to heat the high-density plasma, where possibly the reconnection occurs. The consequent conductive flux drives the evaporation process in a regime that we can call sub-explosive.

Falchi, A.; Teriaca, L.; Maltagliati, L.

2006-12-01

318

Confined laser ablation for single-shot nanoparticle deposition of silver  

NASA Astrophysics Data System (ADS)

Spatially confined laser ablation of silver was used to form long-lived dense plasma for single-shot deposition of a nanoparticle film. The expansion of the ablation plume was restricted by placing a glass substrate at 50 ?m from the silver target surface. Time-resolved optical emission spectroscopy showed that the confined plasma is sustained for longer time than for free ablation. A single laser shot is sufficient to produce a layer of silver nanoparticles on the substrate. In absorption the nanoparticle layer displays a surface plasmon resonance which is comparable to films made by conventional pulsed laser deposition in vacuum.

Donnelly, T.; Lunney, J. G.

2013-10-01

319

Comparison of energy confinement in Doublet III limiter and divertor discharges with ohmic, neutral beam and electron cyclotron heating  

SciTech Connect

Scaling of total energy confinement time with line averaged density, toroidal field, plasma current and total input power is presented for vertically elongated tokamak plasmas, both limiter and divertor configurations, heated by Ohmic, neutral beam injection (NBI), and electron cyclotron heating (ECH) methods. Line averaged density plays no role in confinement in any type of discharge for densities above 2 x 10/sup 19/ m/sup -3/. Toroidal field affects confinement only in Ohmic divertor discharges. Current is the key variable in ECH and NBI discharges; Confinement time increases linearly with current. The similarity of the density and current scaling in NBI and ECH cases argues strongly that these scalings are properties of the auxiliary-heated plasmas in general and are not heating method specific results. Configuration also affects confinement: Expanded boundary divertor discharges show superior confinement for all three heating methods. Finally, the functional form of the variation of stored energy with input power in NBI discharges suggests that confinement time is approaching a new, power independent value at high input power.

Burrell, K.H.; Prater, R.; Ejima, S.; Angel, T.; Armentrout, C.J.; Baur, J.F.; Blau, F.P.; Bramson, G.; Callis, R.W.; Chase, R.P.

1984-09-01

320

Measurements of uranium mass confined in high density plasmas  

NASA Technical Reports Server (NTRS)

An X-ray absorption method for measuring the amount of uranium confined in high density, rf-heated uranium plasmas is described. A comparison of measured absorption of 8 keV X-rays with absorption calculated using Beer Law indicated that the method could be used to measure uranium densities from 3 times 10 to the 16th power atoms/cu cm to 5 times 10 to the 18th power atoms/cu cm. Tests were conducted to measure the density of uranium in an rf-heated argon plasma with UF6 infection and with the power to maintain the discharge supplied by a 1.2 MW rf induction heater facility. The uranium density was measured as the flow rate through the test chamber was varied. A maximum uranium density of 3.85 times 10 to the 17th power atoms/cu cm was measured.

Stoeffler, R. C.

1976-01-01

321

System and method of operating toroidal magnetic confinement devices  

DOEpatents

This invention pertains to methods and arrangements for attaining high beta values in plasma confinement devices. More specifically, this invention pertains to methods for accessing the second stability region of operation in toroidal magnetic confinement devices.

Chance, M.S.; Jardin, S.C.; Stix, T.H.; Grimm, R.C.; Manickam, J.; Okabayashi, M.

1984-08-30

322

Confinement and Tritium Stripping Systems for APT Tritium Processing.  

National Technical Information Service (NTIS)

This report identifies functions and requirements for the tritium process confinement and clean-up system (PCCS) and provides supporting technical information for the selection and design of tritium confinement, clean-up (stripping) and recovery technolog...

R. H. Hsu L. K. Heung

1997-01-01

323

Atomic processes in Inertial Electrostatic Confinement (IEC) devices.  

National Technical Information Service (NTIS)

Inertial Electrostatic Confinement (IEC) is one of the earliest plasma confinement concepts, having first been suggested by P. T. Farnsworth in the 1950s. The concept involves a simple apparatus of concentric spherical electrostatic grids or a combination...

R. A. Nebel L. Turner T. N. Tiouririne D. C. Barnes W. D. Nystrom

1993-01-01

324

28 CFR 115.263 - Reporting to other confinement facilities.  

Code of Federal Regulations, 2013 CFR

...confinement facilities. 115.263 Section 115.263 Judicial Administration DEPARTMENT OF JUSTICE (CONTINUED) PRISON RAPE ELIMINATION ACT NATIONAL STANDARDS Standards for Community Confinement Facilities Official Response Following A...

2013-07-01

325

Analytic, nonlinearly exact solutions for an rf confined plasma  

NASA Astrophysics Data System (ADS)

RF confined electron plasmas are of importance in Paul traps [W. Paul, Rev. Mod. Phys. 62, 531 (1990)]. The stability of such plasmas is unclear and statistical heating arguments have been advanced to explain the observed heating in such plasmas [I. Siemers et al., Phys. Rev. A 38, 5121 (1988)]. This study investigates the nature of a one-dimensional collisionless electron plasma that is confined by an rf field of the form [-B+A cos(?t)]x, where x is the space coordinate and ? is the rf frequency. Nonlinearly exact solutions are obtained. The distribution function and the plasma density are obtained in closed form and have constant shapes with time varying oscillations. These oscillations are at the rf frequency and its harmonics, modulated by a low frequency related to the electron bounce time. The linear limit of weak fields is recovered. Analytic expressions are obtained for the required external field to make it consistent with prescribed distribution functions. These solutions remain valid even in the presence of collisions. Solutions involving multiple species are also obtained, though only for collisionless traps. It is found that the ponderomotive force response needs to be corrected to account for the temperature fluctuations. No stochastic heating is observed in this field configuration.

Shah, Kushal; Ramachandran, Harishankar

2008-06-01

326

Optical confinement in CdTe-based photonic dots  

NASA Astrophysics Data System (ADS)

We demonstrate three-dimensional optical confinement in CdTe-based microcavities. While the vertical confinement is determined by epitaxially grown CdMnTe/CdMgTe Bragg mirrors, the lateral confinement is achieved by defining pillar structures with electron beam lithography and reactive ion etching. The optical confinement is shown by a size-dependent energy splitting between the fundamental and higher photonic modes.

Obert, M.; Wild, B.; Bacher, G.; Forchel, A.; André, R.; Dang, Le Si

2002-02-01

327

Magnetic confinement fusion plasma theory, Task 1  

SciTech Connect

The research performed under this grant during the current year has concentrated on a few key tokamak plasma confinement and heating theory issues: extensive development of a new Chapman-Enskog-like fluid/kinetic hybrid approach to deriving rigorously valid fluid moment equations; applications (neoclassical viscous force, instabilities in the banana-plateau collisionality regime, nonlinear gyroviscous force, unified plasma microinstability equations and their implications, semi-collisional presheath modeling, etc.) of this new formalism; interactions of fluctuating bootstrap-current-driven magnetic islands; determination of net transport processes and equations for a tokamak; and some other topics (extracting more information from heat-pulse-propagation data, modeling of BES fluctuation data, exploring sawtooth effects on energy confinement in DIII-D, divertor X-point modeling). Recent progress and publications in these areas, and in the management of the local NERSC node and fusion theory DECstation 5000 at UW-Madison are summarized briefly in this report.

Callen, J.D.

1991-07-01

328

Approaches to confined alpha diagnostics on ITER  

SciTech Connect

Three approaches to obtain information on the confined fast alphas in the International Thermonuclear Experimental Reactor (ITER) are proposed. The first technique measures the energetic charge exchange (CX) neutrals that result from the alpha collision-induced knock-on fuel ion tails undergoing electron capture on the MeV D neutral beams planned for heating and current drive. The second technique measures the energetic knock-on neutron tail due to alphas using the lengths of the proton recoil tracks produced by neutron collisions in nuclear emulsions. The range of the 14 to 20 MeV recoil protons increases by {approx}140 {mu}m per MeV. The third approach would measure the CX helium neutrals resulting from confined alphas capturing two electrons in the ablation cloud surrounding a dense gas jet that has been proposed for disruption mitigation in ITER.

Fisher, R.K. [General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States)

2004-10-01

329

Confinement improvement by fluctuating input power  

SciTech Connect

An interesting effect of the fluctuating input power on plasma confinement is reported. Specifically, the addition of the sinusoidal perturbation, Asin(wt), to constant power q{sub 0} is shown to promote the confinement, leading to the L-H transition at a lower value of q{sub 0}, as compared to the case of constant q{sub 0} without the sinusoidal perturbation. In general, higher amplitude (A) and lower frequency (w) are found to be more favorable for the L-H transition while an interesting linear relation between A and w leading to the L-H transition is established for different values of q{sub 0}.

Douglas, Sarah; Mohamed, Mabruka; Kim, Eun-jin [School of Mathematics and Statistics, University of Sheffield, Sheffield S3 7RH (United Kingdom)] [School of Mathematics and Statistics, University of Sheffield, Sheffield S3 7RH (United Kingdom)

2013-11-15

330

Confinement and stability of a Crystalline Beam  

SciTech Connect

This technical report defines and describes a Crystalline Beam. This is an ordered state of matter made of electrically charged ions which are moving together in a storage ring with very high density and small velocity spread. In particular, the paper analyses the requirements for the confinement and the stability of the Beam. It is demonstrated that a storage ring made of one circular weak-focusing magnet, similar to a Betatron, is the most suitable for the confinement and stability of the Crystalline Beam. The disruptive effects of drift insertions have also been investigated. Requirements on final densities and velocity spreads are also calculated and reported. A matrix formalism is developed for the design of the storage ring. The important issue of the disruption caused by the curvature of the closed trajectory is not here discussed; it is the subject of a subsequent paper.

Ruggiero, A.G.

1993-05-10

331

Multiscale confining dynamics from holographic RG flows  

NASA Astrophysics Data System (ADS)

We consider renormalization group flows between conformal field theories in five (six) dimensions with a string (M-theory) dual. By compactifying on a circle (torus) with appropriate boundary conditions, we obtain continuous families of confining fourdimensional theories parametrized by the ratio ?flow/?QCD, with ?flow the scale at which the flow between fixed points takes place and ?QCD the confinement scale. We construct the dual geometries explicitly and compute the spectrum of scalar bound states (glueballs). We find a `universal' subset of states common to all the models. We comment on the modifications of these models, and the corresponding fine-tuning, required for a parametrically light `dilaton' state to be present. We also comment on some aspects of these theories as probed by extended objects such as strings and branes.

Elander, Daniel; Faedo, Anton F.; Hoyos, Carlos; Mateos, David; Piai, Maurizio

2014-05-01

332

Inertial electrostatic confinement (IEC) neutron sources  

SciTech Connect

Inertial electrostatic confinement (IEC) is one of the earliest plasma confinement concepts, having first been suggested by P.T. Farnsworth in the 1950s. The concept involves a simple apparatus of concentric spherical electrostatic grids or a combination of grids and magnetic fields. An electrostatic structure is formed from the confluence of electron or ion beams. Gridded IEC systems have demonstrated neutron yields as high as 2 x 10(exp 10) neutrons/sec in steady state. These systems have considerable potential as small, inexpensive, portable neutron sources for assaying applications. Neutron tomography is also a potential application. This paper discusses the IEC concept and how it can be adapted to a steady-state assaying source and an intense pulsed neutron source. Theoretical modeling and experimental results are presented.

Barnes, D.C.; Caramana, E.J.; Janssen, R.D.; Nystrom, W.D.; Tiouririne, T.N.; Trent, B.C.; Miley, G.H.; Javedani, J.

1995-01-01

333

Phase Transitions in Confined Gallium Droplets  

NASA Astrophysics Data System (ADS)

Phase transitions in submicrometric Ga droplets confined in epoxy resin are studied by combining energy-dispersive x-ray diffraction (EDXRD), x-ray absorption fine structure, and single-energy x-ray absorption. The restricted fluid is undercooled down to 150 K while the melting point is depressed down to 254 K. Melting and freezing are sharp processes occurring with temperature broadening of 1 and 10 K, respectively. EDXRD patterns are consistent with that of ?-Ga, while the stable phase at ambient conditions ?-Ga is not found to exist. Appearance of ?-Ga and ?-Ga solid phases and relevance of present results to recent studies of Ga confined in porous glass are discussed.

di Cicco, Andrea

1998-10-01

334

Influenza Outbreak Control in Confined Settings  

PubMed Central

Influenza may rapidly disseminate within populations living in confined settings, causing considerable morbidity and disrupting daily activities. We describe an influenza A outbreak on a military base where 3,000 young adults, most of whom were unvaccinated, lived in close daily contact. Visits to the base clinic by 48 persons with acute respiratory illness within 2 days allowed early identification of this outbreak and prompted immediate epidemiologic investigation. Overall, 85 personnel (2.83% of base population) met the case definition for influenzalike illness. On-site laboratory confirmation with field detection kits, rapid implementation of respiratory illness control protocols, and a mass vaccination campaign were applied to limit disease dissemination. The outbreak was halted 14 days after the mass vaccination campaign was completed. We review the control measures available for controlling influenza outbreaks in confined settings and discuss the role of rapid mass vaccination within this context.

Huerta, Michael; Levy, Yuval; Davidovitch, Nadav; Grotto, Itamar

2005-01-01

335

Spinwaves in Laterally Confined Magnetic Structures  

NASA Astrophysics Data System (ADS)

Recent advances in lithograpic patterning techniques have made it possible to produce high-quality arrays of micrometer size magnetic dots and wires, which are considered a prototype of the next generation magnetic memory. This review covers the current understanding of spin-wave excitations in arrays of magnetic dots and wires. Brillouin light scattering spectroscopy as the main tool as well as the current state of theory of laterally confined spinwaves are discussed. The three most important issues are addressed: the modification of dynamic magnetic properties by patterning due to shape anisotropies, the quantization of spinwaves due to their in-plane confinement in dots and wires, and anisotropic magnetic dipolar coupling between magnetic dots.

Demokritov, Sergey O.; Hillebrands, Burkard

336

NEW APPROACHES TO CONFINED ALPHA DIAGNOSTICS  

SciTech Connect

Three new approaches to obtain information on the confined fast alphas in International Thermonuclear Experimental Reactor (ITER) are proposed. The first technique measures the energetic charge exchange (CX) neutrals that result from the alpha collision-induced knock-on fuel ion tails undergoing electron capture on the MeV D neutral beams planned for heating and current drive. The second technique measures the energetic knock-on neutron tail due to alphas using the lengths of the proton recoil tracks produced by neutron collisions in nuclear emulsions. The range of the 14 to 20 MeV recoil protons increases by {approx}140 microns per MeV. The third approach would measure the CX helium neutrals resulting from confined alphas capturing two electrons in the ablation cloud surrounding a dense gas jet that has been proposed for disruption mitigation in ITER.

FISHER,R.K

2004-04-01

337

Spontaneous Circulation of Confined Active Suspensions  

NASA Astrophysics Data System (ADS)

Many active fluid systems encountered in biology are set in total geometric confinement. Cytoplasmic streaming in plant cells is a prominent and ubiquitous example, in which cargo-carrying molecular motors move along polymer filaments and generate coherent cell-scale flow. When filaments are not fixed to the cell periphery, a situation found both in vivo and in vitro, we observe that the basic dynamics of streaming are closely related to those of a nonmotile stresslet suspension. Under this model, it is demonstrated that confinement makes possible a stable circulating state; a linear stability analysis reveals an activity threshold for spontaneous autocirculation. Numerical analysis of the longtime behavior reveals a phenomenon akin to defect separation in nematic liquid crystals and a high-activity bifurcation to an oscillatory regime.

Woodhouse, Francis G.; Goldstein, Raymond E.

2012-10-01

338

Studies Of Enhanced Confinement In The Columbia Non-Neutral Torus  

SciTech Connect

Recently the measured confinement time in the Columbia Non-neutral Torus (CNT) has been increased by nearly an order of magnitude to 190 ms. Previously, enhanced transport caused in part by the mismatch of constant potential and magnetic surfaces limited confinement times to 20 ms. A conducting boundary conforming to the last closed magnetic flux surface has been installed to minimize potential variation along magnetic surfaces, provide new methods to influence the plasma, and act as an external diagnostic. A summary of new results with the conducting boundary installed will be presented, including discussion of how confinement is influenced by neutral pressure, magnetic field strength, and the effect of biasing individual sectors of the mesh.

Brenner, P. W.; Pedersen, T. Sunn; Hahn, M.; Berkery, J. W.; Lefrancois, R. G. [Columbia University, New York, NY 10027 (United States); Marksteiner, Q. R. [Columbia University, New York, NY 10027 (United States); Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2009-03-30

339

Inertial confinement fusion with light ion beams  

SciTech Connect

Advances are reported in the theory and experiments investigating Inertial Confinement Fusion with light ion beams on the Particle Beam Fusion Accelerator II (PBFA II). Impedance of the accelerating gap, electron-ion instabilities, proton beam generation and focusing at 300 kJ, proton driven target experiments to measure beam non-uniformity, lithium beam generation and focusing at 185 kJ, and plasma opening switch improvements for voltage and power gain are reported.

Vandevender, J.P.; Adams, R.G.; Allshouse, G.O.; Bailey, J.E.; Beig, K.W.; Bloomquist, D.D.; Coats, R.S.; Cook, D.L.; Chandler, G.E.; Cuneo, M.E.; Derzon, M.S.; Desjarlais, M.P.; Dreike, P.L.; Gerber, R.A.; Hanson, D.L.; Humphreys, D.R.; Hussey, T.W.; Johnson, D.J.; Johnson, D.L.; Johnson, W.A.; Kuswa, G.W.; Lee, J.R.; Leeper, R.J.; Lockner, T.R.; Maenchen, J.E.; Matzen, M.K.; McDaniel, D.H.; McKay, P.F.; Mehlhorn, T.A.; Mend

1990-01-01

340

Inertial confinement fusion with light ion beams  

Microsoft Academic Search

Advances are reported in the theory and experiments investigating Inertial Confinement Fusion with light ion beams on the Particle Beam Fusion Accelerator II (PBFA II). Impedance of the accelerating gap, electron-ion instabilities, proton beam generation and focusing at 300 kJ, proton driven target experiments to measure beam non-uniformity, lithium beam generation and focusing at 185 kJ, and plasma opening switch

J. P. Vandevender; R. G. Adams; G. O. Allshouse; J. E. Bailey; K. W. Beig; D. D. Bloomquist; R. S. Coats; D. L. Cook; G. E. Chandler; M. E. Cuneo; M. S. Derzon; M. P. Desjarlais; P. L. Dreike; R. A. Gerber; D. L. Hanson; D. R. Humphreys; T. W. Hussey; D. J. Johnson; D. L. Johnson; W. A. Johnson; G. W. Kuswa; J. R. Lee; R. J. Leeper; T. R. Lockner; J. E. Maenchen; M. K. Matzen; D. H. McDaniel; P. F. McKay; T. A. Mehlhorn; Mend

1990-01-01

341

Light ion driven inertial confinement fusion  

Microsoft Academic Search

Intense light ion beams are being developed to drive inertial confinement fusion (ICF) targets. Recently, intense proton beams have been used to drive two different types of targets in experiments on the Particle Beam Fusion Accelerator. The experiments focused separately on ion deposition physics and on implosion hydrodynamics. In the ion deposition physics experiments, a 3-4 TW\\/cm(exp 2) proton beam

D. L. Cook; R. G. Adams; J. H. Aubert; L. D. Bacon; J. E. Bailey; D. D. Bloomquist; J. D. Boyes; G. A. Chandler; R. S. Coats; J. P. Corley; J. T. Crow; M. E. Cuneo; D. K. Derzon; M. S. Derzon; M. P. Desjarlais; R. J. Dukart; D. L. Fehl; A. B. Filuk; R. A. Gerber; T. A. Haill; D. L. Hanson; D. R. Humphreys; T. W. Hussey; H. L. Ives; D. J. Johnson; D. L. Johnson; R. J. Leeper; R. W. Lemke; T. R. Lockner; J. E. Maenchen; M. K. Matzen; D. H. McDaniel; P. F. McKay; E. J. McGuire; T. A. Mehlhorn; C. W. Mendel; L. P. Mix; W. E. Nelson; C. L. Olson; R. E. Olson; T. D. Pointon; J. W. Poukey; J. P. Quintenz; J. J. Ramirez; T. J. Renk; G. E. Rochau; P. D. Rockett; S. E. Rosenthal; D. C. Rovang; C. L. Ruiz; D. R. Schmitt; D. B. Seidel; S. A. Slutz; R. W. Stinnett; W. A. Stygar; M. A. Sweeney; G. C. Tisone; J. P. VanDevender

1992-01-01

342

Detonation waves induced by a confined wedge  

Microsoft Academic Search

An auto-ignition detonation phenomenon can be initiated by a wedge confined in a channel. A new, self-sustaining, normal detonation wave engine concept is proposed. The detonation processes were numerically modeled with a simplified two-dimensional wedged channel flow that was deemed to emulate a real three-dimensional configuration. The results showed that within certain ranges of incoming flow Mach number or wedge

Frank K. Lu; Huiyuan Fan; Donald R. Wilson

2006-01-01

343

Elastic wave propagation in confined granular systems  

Microsoft Academic Search

We present numerical simulations of acoustic wave propagation in confined\\u000agranular systems consisting of particles interacting with the three-dimensional\\u000aHertz-Mindlin force law. The response to a short mechanical excitation on one\\u000aside of the system is found to be a propagating coherent wavefront followed by\\u000arandom oscillations made of multiply scattered waves. We find that the coherent\\u000awavefront is insensitive

Ellák Somfai; Jean-Noël Roux; Jacco H. Snoeijer; Martin van Hecke; Wim van Saarloos

2005-01-01

344

Fabrication issues of oxide-confined VCSELs  

Microsoft Academic Search

ABSTRACT To insert high performance,oxide-confined vertical-cavity surface-emittinglasers (VCSELs) into the manufacturing arena, we have examined the critical parameters that must be controlled to establish a repeatable and uniform wet thermal oxidation process for AlGaAs. These parameters include the AlAs mole fraction, the sample temperature, the carrier gas flow and the bubbler water temperature. Knowledge,of these critical parameters has enabled the

K. M. Geib; K. D. Choquette; H. Q. Hou; B. E. Hammons

345

Deuterium anions in inertial electrostatic confinement devices  

Microsoft Academic Search

A magnetic deflection-energy analyzer and Faraday trap diagnostic have been used to make measurements of divergent deuterium anion flow in the inertial electrostatic confinement experiment at the University of Wisconsin-Madison (UW-IEC) [J. F. Santarius, G. L. Kulcinski, R. P. Ashley, D. R. Boris, B. B. Cipiti, S. K. Murali, G. R. Piefer, R. F. Radel, I. E. Radel, and A.

D. R. Boris; E. Alderson; G. Becerra; D. C. Donovan; B. Egle; G. A. Emmert; L. Garrison; G. L. Kulcinski; J. F. Santarius; C. Schuff; S. J. Zenobia

2009-01-01

346

Yukawa particles in a confining potential.  

PubMed

We study the density distribution of repulsive Yukawa particles confined by an external potential. In the weak coupling limit, we show that the mean-field theory is able to accurately account for the particle distribution. In the strong coupling limit, the correlations between the particles become important and the mean-field theory fails. For strongly correlated systems, we construct a density functional theory which provides an excellent description of the particle distribution, without any adjustable parameters. PMID:25005276

Girotto, Matheus; Dos Santos, Alexandre P; Colla, Thiago; Levin, Yan

2014-07-01

347

LDV Measurement of Confined Parallel Jet Mixing  

SciTech Connect

Laser Doppler Velocimetry (LDV) measurements were taken in a confinement, bounded by two parallel walls, into which issues a row of parallel jets. Two-component measurements were taken of two mean velocity components and three Reynolds stress components. As observed in isolated three dimensional wall bounded jets, the transverse diffusion of the jets is quite large. The data indicate that this rapid mixing process is due to strong secondary flows, transport of large inlet intensities and Reynolds stress anisotropy effects.

R.F. Kunz; S.W. D'Amico; P.F. Vassallo; M.A. Zaccaria

2001-01-31

348

Ionization balance in inertial confinement fusion hohlraums.  

PubMed

We present the first x-ray spectroscopic measurements of the ionization balance in inertial confinement fusion hohlraums supported by 4omega Thomson scattering diagnostics. The experimental data show agreement with non-LTE radiation-hydrodynamic calculations of the averaged Au charge state and electron temperatures. These findings are consistent with the successful integrated modeling of the hohlraum radiation fields. Comparisons with detailed synthetic spectra calculations show that the experimental ionization distribution is slightly shifted indicating nonsteady state kinetics. PMID:11461624

Glenzer, S H; Fournier, K B; Wilson, B G; Lee, R W; Suter, L J

2001-07-23

349

Laser driven instabilities in inertial confinement fusion  

SciTech Connect

Parametric instabilities excited by an intense electromagnetic wave in a plasma is a fundamental topic relevant to many applications. These applications include laser fusion, heating of magnetically-confined plasmas, ionospheric modification, and even particle acceleration for high energy physics. In laser fusion, these instabilities have proven to play an essential role in the choice of laser wavelength. Characterization and control of the instabilities is an ongoing priority in laser plasma experiments. Recent progress and some important trends will be discussed. 8 figs.

Kruer, W.L.

1990-06-04

350

Simulation of Spheromak Evolution and Energy Confinement  

Microsoft Academic Search

Electron temperatures near 400 eV were observed transiently in the Los Alamos CTX spheromak experiment.[1] Temperatures of 100-200 eV have been observed in the SSPX spheromak.[2] Understanding the energy confinement in these experiments is a challenging problem. Results from numerical simulations with the NIMROD nonlinear resistive MHD code (at zero or finite plasma pressure) have shown that closed flux surfaces

Bruce I. Cohen; E Hooper; R Cohen; D Hill; H McLean; R Wood; S Woodruff; C Sovinec; G Cone

2004-01-01

351

Confinement Vessel Assay System: Calibration and Certification Report  

Microsoft Academic Search

Los Alamos National Laboratory has a number of spherical confinement vessels (CVs) remaining from tests involving nuclear materials. These vessels have an inner diameter of 6 feet with 1 to 2 inch thick steel walls. The goal of the Confinement Vessel Disposition (CVD) project is to remove debris and reduce contamination inside the vessels. The Confinement Vessel Assay System (CVAS)

Katherine C. Frame; Mark M. Bourne; William J. Crooks; Louise Evans; Cipriano Gomez; Douglas R. Mayo; David K. Miko; William R. Salazar; Sy Stange; Georgiana M. Vigil

2012-01-01

352

Instability studies on a spherical inertial electrostatic confinement  

Microsoft Academic Search

The spherical inertial electrostatic confinement concept offers an alternative fusion plasma confinement scheme, where charged particles are accelerated and confined electrostatically with a series of biased spherical concentric electrodes. The inertia of the accelerated ions compresses the ions and builds up the space charge at the center of the cathode grid. The space charge of the ions attracts electrons which

Hyung Jin Kim

2006-01-01

353

Confined Turbulent Swirling Recirculating Flow Predictions. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

Turbulent swirling flow, the STARPIC computer code, turbulence modeling of turbulent flows, the k-xi turbulence model and extensions, turbulence parameters deduction from swirling confined flow measurements, extension of the k-xi to confined swirling recirculating flows, and general predictions for confined turbulent swirling flow are discussed.

Abujelala, M. T.

1984-01-01

354

Ambipolar potential formation and axial confinement in TMX  

Microsoft Academic Search

TMX experimental data on ambipolar potential control and on the accompanying electrostatic confinement are reported. In the radial core of the central cell, measurements of electrostatic potentials of 150 V which augment axial ion confinement are in agreement with predictions using the Maxwell-Boltzmann result. Central-cell ion confinement was observed to scale according to electrostatic potential theory up to average enhancement

D. L. Correll; S. L. Allen; T. A. Capser; J. F. Clauser; P. Coakley; F. H. Coensgen; W. Condit; W. F. Cummins; J. C. Davis; R. P. Drake; J. H. Foote; A. H. Futch; R. K. Goodman; D. P. Grubb; G. A. Hallock; E. B. Hooper; R. S. Hornady; A. L. Hunt; C. V. Karmendy; A. W. Molvik; W. E. Nexsen; W. L. Pickles; P. Poulsen; T. C. Simonen; B. W. Stallard; O. T. Strand

1982-01-01

355

Impacts of confinement and research needs to underpin welfare standards  

Microsoft Academic Search

Confinement and its impacts The meaning of the term confinement requires some consideration, as like the term welfare, it is open to interpretation. Wild animals are generally considered to be free- roaming and in that sense are not usually considered to be confined. However, this may not be the case for wildlife living in isolated fragments of habitat or wildlife

John L. Barnett

356

Industrial Applications to the Inertial Electrostatic Confinement Configuration  

Microsoft Academic Search

Since Fransworth's observation of inertial electrostatic confinement in the 1930's several applications have been proposed and studied with fusion being the main focus. Inertial electrostatic confinement is a scheme in which ions are focused and confined by means of either an electrostatic field or a combination of electrostatic and magnetic fields to produce an effective spherical potential well. Due to

Elijah Martin; Steve Shannon; Mohamed Bourham

2009-01-01

357

Confined modes in dual-state two-dimensional waveguides.  

PubMed

We consider the confined modes in dual-state two-dimensional waveguides in which each slab segment of waveguides can support two vertically confined modes with different effective indices. A matrix formulation is developed to extend the conventional effective-index method to investigate the two-dimensional confinement in multistate waveguides. The results are presented and discussed. PMID:19829532

Gu, C; Yeh, P; Botez, D

1994-01-01

358

Interpretation of earth tide response of three deep, confined aquifers  

SciTech Connect

The response of a confined, areally infinite aquifer to external loads imposed by earth tides is examined. Because the gravitational influence of celestial objects occurs over large areas of the earth, the confined aquifer is assumed to respond in an undrained fashion. Since undrained response is controlled by water compressibility, earth tide response can be directly used only to evaluate porous medium compressibility if porosity is known. Moreover, since specific storage S/sub s/ quantifies a drained behavior of the porous medium, one cannot directly estimate S/sub s/from earth tide response. Except for the fact that barometric changes act both on the water surface in the well and on the aquifer as a whole while stress changes associated with earth tides act only in the aquifer, the two phenomena influence the confined aquifer in much the same way. In other words, barometric response contains only as much information on the elastic properties of the aquifer as the earth tide response does. Factors such as well bore storage, aquifer transmissivity, and storage coefficient contribute to time lag and damping of the aquifer response as observed in the well. Analysis shows that the observation of fluid pressure changes alone, without concurrent measurement of external stress changes, is sufficient to interpret uniquely earth tide response. In the present work, change in external stress is estimated from dilatation by assuming a reasonable value for bulk modulus. Earth tide response of geothermal aquifers from Marysville, Montana. East Mesa, California; and Raft River Valley, Idaho, were analyzed, and the ratio of S/sub 3/ to porosity was estimated. Comparison of these estimates with independent pumping tests show reasonable agreement.

Narasimhan, T.N.; Kanehiro, B.Y.; Witherspoon, P.A.

1984-03-10

359

Radioactivity Confinement Studies Within the SEAL Program  

NASA Astrophysics Data System (ADS)

In the framework of the European SEAL program, investigations have been performed with the aim of optimizing the second confinement function and plant layout with respect to normal operation as well as abnormal operation, including accident conditions. This has been done for two conceptual fusion reactor designs: one using water as the coolant and the other using helium. The starting point of these investigations was the SEAFP project design. For the water-cooled reactor design the studies were focused on design options such as pressure suppression spray system, pressure suppression pool with closed containment or with venting to gravel bed filter and stack, and separate expansion volume optionally operated with a vacuum and equipped with spray system. Similar analyses were performed for the helium-cooled reactor design. The analyses were focused on design options comprising a single, large confinement volume or a vent duct connected to an expansion volume operated at vacuum in comparison with the SEAFP Model 1. The thermal-hydraulic analyses performed with the MELCOR code provide an integrated assessment of the cooling loop and confinement system dynamics.

Collén, Jan; Matsugu, Ron; Natalizio, Antonio; Shen, Kecheng

1997-09-01

360

Fast ion JET diagnostics: confinement and losses  

SciTech Connect

A study of magnetically confined fast ions in tokamaks plays an important role in burning plasma research. To reach ignition and steady burning of a reactor plasma an adequate confinement of energetic ions produced by NBI heating, accelerated with ICRF and born in fusion reactions is essential to provide efficient heating of the bulk plasma. Thus, investigation of the fast ion behaviour is an immediate task for present-day large machines, such as JET, in order to understand the main mechanisms of slowing down, redistribution and losses, and to develop optimal plasma scenarios. Today's JET has an enhanced suite of fast ion diagnostics both of confined and lost ions that enable to significantly contribute to this important area of research. Fast ion populations of p, d, t, {sup 3}He and {sup 4}He, made with ICRF, NBI, and fusion reactions have been investigated in experiments on JET with sophisticated diagnostics in conventional and shear-reversed plasmas, exploring a wide range of effects. This paper will introduce to the JET fast-ion diagnostic techniques and will give an overview of recent observations. A synergy of the unique diagnostic set was utilised in JET, and studies of the response of fast ions to MHD modes (e.g. tornado modes, sawtooth crashes), fast {sup 3}He-ions behaviour in shear-reversed plasmas are impressive examples of that. Some results on fast ion losses in JET experiments with various levels of the toroidal field ripple will be demonstrated.

Kiptily, V. G.; Pinches, S. D.; Sharapov, S. E.; Syme, D. B. [Euratom/UKAEA Fusion Association, Culham Science Centre, Abingdon, Oxon (United Kingdom); Borba, D.; Nabais, F. [Euratom/IST Fusion Association, Centro de Fusao Nuclear, 1049-001 Lisboa (Portugal); Cecil, F. E. [Colorado School of Mines, Golden, CO (United States); Cecconello, M. [Association EURATOM-VR, Royal Institute of Technology KTH, Stockholm (Sweden); Darrow, D.; Hill, K. [Princeton Plasma Physics Lab, Princeton NJ (United States); Goloborod'ko, V.; Yavorskij, V. [Euratom/OEAW Association, Institute for Theoretical Physics, University of Innsbruck (Austria); Institute for Nuclear Research, Kiev (Ukraine); Johnson, T. [Euratom--VR Association, Alfven Laboratory, Royal Institute of Technology, 10044 Stockholm (Sweden); Murari, A. [Consorzio RFX--Associazione Euratom-Enea sulla Fusione, I-35127 Padova (Italy); Reich, M. [Euratom/MPI fuaer Plasmaphysik Association, Garching (Germany); Chugunov, I. N.; Gin, D. B.; Shevelev, A. E. [Ioffe Physico-Thechnical Institute, 194021 St. Petersburg (Russian Federation); Gorini, G. [Istituto di Fisica del Plasma, EURATOM-ENEA-CNR Association, Milan (Italy); Zoita, V. [Euratom-MedC Association, National Institute for Laser, Plasma and Radiation Physics, Bucharest (Romania)

2008-03-12

361

Simulating tumor growth in confined heterogeneous environments  

NASA Astrophysics Data System (ADS)

The holy grail of computational tumor modeling is to develop a simulation tool that can be utilized in the clinic to predict neoplastic progression and propose individualized optimal treatment strategies. In order to develop such a predictive model, one must account for many of the complex processes involved in tumor growth. One interaction that has not been incorporated into computational models of neoplastic progression is the impact that organ-imposed physical confinement and heterogeneity have on tumor growth. For this reason, we have taken a cellular automaton algorithm that was originally designed to simulate spherically symmetric tumor growth and generalized the algorithm to incorporate the effects of tissue shape and structure. We show that models that do not account for organ/tissue geometry and topology lead to false conclusions about tumor spread, shape and size. The impact that confinement has on tumor growth is more pronounced when a neoplasm is growing close to, versus far from, the confining boundary. Thus, any clinical simulation tool of cancer progression must not only consider the shape and structure of the organ in which a tumor is growing, but must also consider the location of the tumor within the organ if it is to accurately predict neoplastic growth dynamics.

Gevertz, Jana L.; Gillies, George T.; Torquato, Salvatore

2008-09-01

362

West European magnetic confinement fusion research  

NASA Astrophysics Data System (ADS)

This report presents a technical assessment and review of the West European program in magnetic confinement fusion by a panel of U.S. scientists and engineers active in fusion research. Findings are based on the scientific and technical literature, on laboratory reports and preprints, and on the personal experiences and collaborations of the panel members. Concerned primarily with developments during the past 10 years, from 1979 to 1989, the report assesses West European fusion research in seven technical areas: tokamak experiments; magnetic confinement technology and engineering; fusion nuclear technology; alternate concepts; theory; fusion computations; and program organization. The main conclusion emerging from the analysis is that West European fusion research has attained a position of leadership in the international fusion program. This distinction reflects in large measure the remarkable achievements of the Joint European Torus (JET). However, West European fusion prominence extends beyond tokamak experimental physics: the program has demonstrated a breadth of skill in fusion science and technology that is not excelled in the international effort. It is expected that the West European primacy in central areas of confinement physics will be maintained or even increased during the early 1990's. The program's maturity and commitment kindle expectations of dramatic West European advances toward the fusion energy goal. For example, achievement of fusion breakeven is expected first in JET, before 1995.

McKenney, B. L.; McGrain, M.

1990-01-01

363

Confinement of atoms under general boundary conditions  

NASA Astrophysics Data System (ADS)

The energy spectrum of a nonrelativistic quantum particle and hydrogen-like atom is considered under the most general conditions of confinement in a spatial box (vacuum cavity). It is shown that the rearrangement of the lowest energy levels occurring in this case turns out to be considerably more significant when compared with the case of confinement achieved by the impenetrable potential barrier. The role in the rearrangement of this level, played by the von Neumann-Wigner level repulsion effect, is emphasized. For an atom confined in a spherical cavity of radius R, it is also shown that, when the role of the cavity boundary is played by the surface layer of nonzero depth d, the atomic ground state possesses a deep and pronounced minimum for the physically reasonable width and depth of that surface layer, in which the binding energy turns out to be an order of magnitude larger than that of the lowest 1 s-level of a free atom E 1 s . Also, it becomes possible to achieve a mode when the binding energy of an atom is noticeably higher than E 1 s at R on the order of 10-100 nm.

Sveshnikov, K. A.; Roenko, A. A.

2013-09-01

364

Reverse Monte Carlo modeling in confined systems.  

PubMed

An extension of the well established Reverse Monte Carlo (RMC) method for modeling systems under close confinement has been developed. The method overcomes limitations induced by close confinement in systems such as fluids adsorbed in microporous materials. As a test of the method, we investigate a model system of (36)Ar adsorbed into two zeolites with significantly different pore sizes: Silicalite-I (a pure silica form of ZSM-5 zeolite, characterized by relatively narrow channels forming a 3D network) at partial and full loadings and siliceous Faujasite (which exhibits relatively wide channels and large cavities). The model systems are simulated using grand canonical Monte Carlo and, in each case, its structure factor is used as input for the proposed method, which shows a rapid convergence and yields an adsorbate microscopic structure in good agreement with that of the model system, even to the level of three body correlations, when these are induced by the confining media. The application to experimental systems is straightforward incorporating factors such as the experimental resolution and appropriate q-sampling, along the lines of previous experiences of RMC modeling of powder diffraction data including Bragg and diffuse scattering. PMID:24437893

Sánchez-Gil, V; Noya, E G; Lomba, E

2014-01-14

365

Reverse Monte Carlo modeling in confined systems  

NASA Astrophysics Data System (ADS)

An extension of the well established Reverse Monte Carlo (RMC) method for modeling systems under close confinement has been developed. The method overcomes limitations induced by close confinement in systems such as fluids adsorbed in microporous materials. As a test of the method, we investigate a model system of 36Ar adsorbed into two zeolites with significantly different pore sizes: Silicalite-I (a pure silica form of ZSM-5 zeolite, characterized by relatively narrow channels forming a 3D network) at partial and full loadings and siliceous Faujasite (which exhibits relatively wide channels and large cavities). The model systems are simulated using grand canonical Monte Carlo and, in each case, its structure factor is used as input for the proposed method, which shows a rapid convergence and yields an adsorbate microscopic structure in good agreement with that of the model system, even to the level of three body correlations, when these are induced by the confining media. The application to experimental systems is straightforward incorporating factors such as the experimental resolution and appropriate q-sampling, along the lines of previous experiences of RMC modeling of powder diffraction data including Bragg and diffuse scattering.

Sánchez-Gil, V.; Noya, E. G.; Lomba, E.

2014-01-01

366

The Confinement of Neptune's Ring Arcs  

NASA Astrophysics Data System (ADS)

The stability of the narrow ring arcs of Neptune has been a puzzle since their discovery. First detected in 1984 from the Earth in stellar occultations and imaged by the Voyager spacecraft in 1989, the 5 arcs spanning approximately 40 deg in longitude are apparently confined against the rapid azimuthal and radial spreading that results from energy dissipation in inter-particle collisions. Voyager data were used to argue in favor of an arc confinement model (Goldreich et al. AJ 1986; Porco, Science 1991) that relies on both the vertical and mean angular motions of the nearby Neptunian moon, Galatea, to produce a pair of Lindblad (LR) and corotation inclination (CIR) resonances capable of trapping ring particles into a sequence of arcs. However, HST and Earth-based observations taken in 1998 (Dumas et al. Nature 1999; Sicardy et al. Nature 1999) indicate a revised arc mean angular motion which displaces the arcs away from the CIR, leaving their stability once again unexplained. In this presentation, we will discuss the workings of a hitherto neglected resonance which relies on Galatea's orbital eccentricity and which, together with the LR, is likely responsible for the angular confinement of the arcs. The action of this resonance, which operates through the precession of Galatea's eccentric orbit forced by the arcs' inertia, will allow a determination of the arcs' mass from future measurements of Galatea's eccentricity. We acknowledge the financial support of NASA's Planetary Geology and Geophysics Program and the Southwest Research Institute's Internal Research Grant program.

Porco, C.; Namouni, F.

2002-09-01

367

Improved confinement in high li lower hybrid driven steady state plasmas in TORE SUPRA  

NASA Astrophysics Data System (ADS)

The global energy confinement of combined ohmic and lower hybrid driven TORE SUPRA plasmas has been analysed at various densities. In contradiction to the L mode ITER scaling law, this analysis indicates that the global energy confinement time depends strongly on the plasma density. Furthermore, the thermal electron energy content of steady state discharges is found to be in good agreement with the global Rebut-Lallia-Watkins (RLW) scaling law. Current ramp experiments show an enhancement of the global energy confinement with the internal inductance, li. These results have been extended to steady state regimes with lower hybrid current drive. Improved confinement has been obtained in a high li steady state plasma (li=1.7), where the modification of the current profile by lower hybrid waves leads to an increase in the central value of the safety factor (q?(0) approx 2). In this case, the global confinement time is shown to exceed the value predicted by the RLW scaling law by 40%

Hoang, G. T.; Gil, C.; Joffrin, E.; Moreau, D.; Becoulet, A.; Bibet, P.; Bizarro, J. P.; Budny, R. V.; Carrasco, J.; Coulon, J. P.; DeMichelis, C.; Dudok de Wit, T.; Monier-Garbet, P.; Goniche, M.; Guirlet, R.; Hutter, T.; Kaye, S. M.; Lasalle, J.; Laurent, L.; Lecoustey, P.; Litaudon, X.; Mattioli, M.; Peysson, Y.; Pecquet, A.-L.; Rey, G.; Sabbagh, S. A.; Saoutic, B.; Tonon, G.; Vallet, J. C.

1994-01-01

368

Excess-entropy scaling of dynamics for a confined fluid of dumbbell-shaped particles  

NASA Astrophysics Data System (ADS)

We use molecular simulation to study the ability of excess entropy scaling relationships to describe the kinetic properties of a confined molecular system. We examine a model for a confined fluid consisting of dumbbell-shaped molecules that interact with atomistically detailed pore walls via a Lennard-Jones potential. We obtain kinetic, thermodynamic, and structural properties of the system at three wall-fluid interaction strengths and over a temperature range that includes sub- and super-critical conditions. Four dynamic properties are considered: translational and rotational diffusivities, a characteristic relaxation time for rotational motion, and a collective relaxation time stemming from analysis of the coherent intermediate scattering function. We carefully consider the reference state used to define the excess entropy of a confined fluid. Three ideal-gas reference states are considered, with the cases differentiated by the extent to which one-body spatial and orientational correlations are accounted for in the reference state. Our results indicate that a version of the excess entropy that includes information related to the one-body correlations in a confined fluid serves as the best scaling variable for dynamic properties. When adopting such a definition for the reference state, to a very good approximation, bulk and confined data for a specified dynamic property at a given temperature collapse onto a common curve when plotted against the excess entropy.

Chopra, Ravi; Truskett, Thomas M.; Errington, Jeffrey R.

2010-10-01

369

Electrostatically Shielded Quantum Confined Stark Effect Inside Polar Nanostructures  

PubMed Central

The effect of electrostatic shielding of the polarization fields in nanostructures at high carrier densities is studied. A simplified analytical model, employing screened, exponentially decaying polarization potentials, localized at the edges of a QW, is introduced for the ES-shielded quantum confined Stark effect (QCSE). Wave function trapping within the Debye-length edge-potential causes blue shifting of energy levels and gradual elimination of the QCSE red-shifting with increasing carrier density. The increase in the e?h wave function overlap and the decrease of the radiative emission time are, however, delayed until the “edge-localization” energy exceeds the peak-voltage of the charged layer. Then the wave function center shifts to the middle of the QW, and behavior becomes similar to that of an unbiased square QW. Our theoretical estimates of the radiative emission time show a complete elimination of the QCSE at doping densities ?1020 cm?3, in quantitative agreement with experimental measurements.

2009-01-01

370

High-Density Carbon Ablators for Inertial Confinement Fusion  

NASA Astrophysics Data System (ADS)

A series of experiments on the Omega laser have been preformed to measure high-density carbon (HDC) ablator performance for indirect drive inertial confinement fusion (ICF). The Omega laser was used to generate shaped laser pulses with varying powers during the first nanosecond of the drive to investigate drive pressures between 1.7 Mb and 7.5 Mb. The total neutron yield, ion temperature, neutron bang time and x-ray bang time were measured and compared to simulations. Experiments using HDC ablators are planned for the National Ignition Facility and will be discussed. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and supported by LDRD-11-ERD-075.

Ross, James; Amendt, Peter; Callahan, Debbie; Prisbrey, Shon; Suter, Larry; Glenzer, Siegfried

2012-10-01

371

Homogeneous hydrodynamics of a collisional model of confined granular gases  

NASA Astrophysics Data System (ADS)

The hydrodynamic equation governing the homogeneous time evolution of the temperature in a model of confined granular gas is studied by means of the Enskog equation. The existence of a normal solution of the kinetic equation is assumed as a condition for hydrodynamics. Dimensional analysis implies a scaling of the distribution function that is used to determine it in the first Sonine approximation, with a coefficient that evolves in time through its dependence on the temperature. The theoretical predictions are compared to numerical results obtained by the direct simulation Monte Carlo method and a good agreement is found. The relevance of the normal homogeneous distribution function to derive inhomogeneous hydrodynamic equations, for instance using the Champan-Enskog algorithm, is indicated.

Brey, J. Javier; Maynar, P.; García de Soria, M. I.; Buzón, V.

2014-05-01

372

Stationary shapes of confined rotating magnetic liquid droplets.  

PubMed

We study the family of steady shapes which arise when a magnetic liquid droplet is confined in a rotating Hele-Shaw cell and subjected to an azimuthal magnetic field. Two different scenarios are considered: first, the magnetic fluid is assumed to be a Newtonian ferrofluid, and then it is taken as a viscoelastic magnetorheological fluid. The influence of the distinct material properties of the fluids on the ultimate morphology of the emerging stationary patterns is investigated by using a vortex-sheet formalism. Some of these exact steady structures are similar to the advanced time patterns obtained by existing time-evolving numerical simulations of the problem. A weakly nonlinear approach is employed to examine this fact and to gain analytical insight about relevant aspects related to the stability of such exact stationary solutions. PMID:21230182

Lira, Sérgio A; Miranda, José A; Oliveira, Rafael M

2010-09-01

373

Monte Carlo simulations of supercoiled DNAs confined to a plane.  

PubMed Central

Recent advances in atomic force microscopy (AFM) have enabled researchers to obtain images of supercoiled DNAs deposited on mica surfaces in buffered aqueous milieux. Confining a supercoiled DNA to a plane greatly restricts its configurational freedom, and could conceivably alter certain structural properties, such as its twist and writhe. A program that was originally written to perform Monte Carlo simulations of supercoiled DNAs in solution was modified to include a surface potential. This potential flattens the DNAs to simulate the effect of deposition on a surface. We have simulated transfers of a 3760-basepair supercoiled DNA from solution to a surface in both 161 and 10 mM ionic strength. In both cases, the geometric and thermodynamic properties of the supercoiled DNAs on the surface differ significantly from the corresponding quantities in solution. At 161 mM ionic strength, the writhe/twist ratio is 1.20-1.33 times larger for DNAs on the surface than for DNAs in solution and significant differences in the radii of gyration are also observed. Simulated surface structures in 161 mM ionic strength closely resemble those observed by AFM. Simulated surface structures in 10 mM ionic strength are similar to a minority of the structures observed by AFM, but differ from the majority of such structures for unknown reasons. In 161 mM ionic strength, the internal energy (excluding the surface potential) decreases substantially as the DNA is confined to the surface. Evidently, supercoiled DNAs in solution are typically deformed farther from the minimum energy configuration than are the corresponding surface-confined DNAs. Nevertheless, the work (Delta A(int)) done on the internal coordinates, which include uniform rotations at constant configuration, during the transfer is positive and 2.6-fold larger than the decrease in internal energy. The corresponding entropy change is negative, and its contribution to Delta A(int) is positive and exceeds the decrease in internal energy by 3.6 fold. The work done on the internal coordinates during the solution-to-surface transfer is directed primarily toward reducing their entropy. Evidently, the number of configurations available to the more deformed solution DNA is vastly greater than for the less deformed surface-confined DNA.

Fujimoto, Bryant S; Schurr, J Michael

2002-01-01

374

Particle and recycling control in translation, confinement, and sustainment upgrade  

NASA Astrophysics Data System (ADS)

Previous work in the translation, confinement, and sustainment upgrade (TCSU) device [H. Y. Guo et al., Phys. Plasmas 15, 056101 (2008)] demonstrated improved plasma parameters; higher temperature, higher poloidal magnetic field, increased current drive, and increased energy confinement, for rotating magnetic field (RMF) driven field reversed configurations (FRC) relative to the earlier TCS device. This was accomplished by improving vacuum conditions and using moderate wall heating (~100 °C) and glow discharge cleaning for wall conditioning. Two new wall conditioning techniques, siliconization and titanium gettering, have been employed to further reduce impurities and control recycling. Both techniques reduced oxygen line radiation by an order of magnitude, and total radiated power by 50%, but led to little change in overall FRC performance, reinforcing the earlier conclusion that TCSU FRCs are not radiation dominated. Titanium gettering substantially reduced deuterium recycling, requiring a new method of fueling to be developed. This is the first time a FRC has been operated without using wall recycling as the primary method of fueling. The low-recycling FRCs, maintained by enhanced puff fueling, performed similarly to standard recycling fueled FRCs in terms of a key current drive parameter Be/B?, the ratio of maximum sustained poloidal field to applied RMF field, but better density control allowed for higher temperatures.

Grossnickle, J. A.; Vlases, G. C.; Hoffman, A. L.; Melnik, P. A.; Milroy, R. D.; Tankut, A.; Velas, K. M.

2010-03-01

375

Classical scattering of charged particles confined on an inhomogeneous helix.  

PubMed

We explore the effects arising due to the coupling of the center of mass and relative motion of two charged particles confined on an inhomogeneous helix with a locally modified radius. It is first proven that a separation of the center of mass and the relative motion is provided if and only if the confining manifold represents a homogeneous helix. In this case, bound states of repulsively Coulomb interacting particles occur. For an inhomogeneous helix, the coupling of the center of mass and relative motion induces an energy transfer between the collective and relative motion, leading to dissociation of initially bound states in a scattering process. Due to the time reversal symmetry, a binding of the particles out of the scattering continuum is thus equally possible. We identify the regimes of dissociation for different initial conditions and provide an analysis of the underlying phase space via Poincaré surfaces of section. Bound states inside the inhomogeneity as well as resonant states are identified. PMID:24229295

Zampetaki, A V; Stockhofe, J; Krönke, S; Schmelcher, P

2013-10-01

376

Particle and recycling control in translation, confinement, and sustainment upgrade  

SciTech Connect

Previous work in the translation, confinement, and sustainment upgrade (TCSU) device [H. Y. Guo et al., Phys. Plasmas 15, 056101 (2008)] demonstrated improved plasma parameters; higher temperature, higher poloidal magnetic field, increased current drive, and increased energy confinement, for rotating magnetic field (RMF) driven field reversed configurations (FRC) relative to the earlier TCS device. This was accomplished by improving vacuum conditions and using moderate wall heating (approx100 deg. C) and glow discharge cleaning for wall conditioning. Two new wall conditioning techniques, siliconization and titanium gettering, have been employed to further reduce impurities and control recycling. Both techniques reduced oxygen line radiation by an order of magnitude, and total radiated power by 50%, but led to little change in overall FRC performance, reinforcing the earlier conclusion that TCSU FRCs are not radiation dominated. Titanium gettering substantially reduced deuterium recycling, requiring a new method of fueling to be developed. This is the first time a FRC has been operated without using wall recycling as the primary method of fueling. The low-recycling FRCs, maintained by enhanced puff fueling, performed similarly to standard recycling fueled FRCs in terms of a key current drive parameter B{sub e}/B{sub o}mega, the ratio of maximum sustained poloidal field to applied RMF field, but better density control allowed for higher temperatures.

Grossnickle, J. A.; Vlases, G. C.; Hoffman, A. L.; Melnik, P. A.; Milroy, R. D.; Tankut, A.; Velas, K. M. [Redmond Plasma Physics Laboratory, University of Washington, 14700 NE 95th St., Suite 100, Redmond, Washington 98052 (United States)

2010-03-15

377

Fast ion relaxation and confinement in the gas dynamic trap  

NASA Astrophysics Data System (ADS)

Studies of the relaxation and confinement of hot anisotropic ions are considered to be the key elements of the gas dynamic trap (GDT) experimental research programme. The method of confinement study described consists essentially in the comparison of measured ion parameters with those predicted by computer simulations. To realize this approach a set of diagnostics for the measurements of local and global parameters of the fast ions has been developed. In particular, this set includes diagnostics to measure the local energy and the angular distribution functions. For numerical studies of the fast ion dynamics a Monte Carlo code based on the theory of two body Coulomb collisions has been elaborated. Comparison of the experimental data with the results of the simulation clearly demonstrates that the fast ion characteristic relaxation times in the warm target plasma are close to those determined by binary Coulomb collisions. Significant anomalous energy losses or scattering of fast ions have not been observed as yet. The measurements provide a maximum density of the fast ions with mean energy of about 8 keV up to 1013 cm-3, in good agreement with computer simulations. The increase of the neutral beam power and improved vacuum conditions of GDT made possible the access to plasma ? of as high as 30%.

Anikeev, A. V.; Bagryansky, P. A.; Ivanov, A. A.; Karpushov, A. N.; Korepanov, S. A.; Maximov, V. V.; Murakhtin, S. V.; Smirnov, A. Yu.; Noack, K.; Otto, G.

2000-04-01

378

Bandpass Filtering of DNA Elastic Modes Using Confinement and Tension  

PubMed Central

During a variety of biological and technological processes, biopolymers are simultaneously subject to both confinement and external forces. Although significant efforts have gone into understanding the physics of polymers that are only confined, or only under tension, little work has been done to explore the effects of the interplay of force and confinement. Here, we study the combined effects of stretching and confinement on a polymer's configurational freedom. We measure the elastic response of long double-stranded DNA molecules that are partially confined to thin, nanofabricated slits. We account for the data through a model in which the DNA's short-wavelength transverse elastic modes are cut off by applied force and the DNA's bending stiffness, whereas long-wavelength modes are cut off by confinement. Thus, we show that confinement and stretching combine to permit tunable bandpass filtering of the elastic modes of long polymers.

Lin, Jun; Persson, Fredrik; Fritzsche, Joachim; Tegenfeldt, Jonas O.; Saleh, Omar A.

2012-01-01

379

Confinement and propagation characteristics of subwavelength plasmonic modes  

NASA Astrophysics Data System (ADS)

We have studied subwavelength confinement of the surface plasmon polariton modes of various plasmonic waveguides and examined their relative merits using a graphical parametric representation of their confinement and propagation characteristics. While the same plasmonic phenomenon governs mode confinement in all these waveguides, the various architectures can exhibit distinctive behavior in terms of effective mode area and propagation distance. We found that the waveguides based on metal and one dielectric material show a similar trade-off between energy confinement and propagation distance. However, a hybrid plasmon waveguide, incorporating metal, low index and high index dielectric materials, exhibits longer propagation distances for the same degree of confinement. We also point out that plasmonic waveguides with sharp features can provide an extremely strong local field enhancement, which is not necessarily accompanied by strong confinement of the total electromagnetic energy. In these waveguides, a mode may couple strongly to nearby atoms, but suffer relatively low propagation losses due to weak confinement.

Oulton, R. F.; Bartal, G.; Pile, D. F. P.; Zhang, X.

2008-10-01

380

Photoluminescence of quantum-confined semiconductor structures  

NASA Astrophysics Data System (ADS)

Different aspects of the photoluminescence from semiconductor quantum-confined structures are studied in this dissertation, for a better understanding of fundamental physics of semiconductors. The precursor of any photoluminescence study is the characterization of the linear optical properties of the semiconductor structures. High resolution absorption measurements were performed in order to study the interplay of disorder and acoustic phonon scattering in a quantum well. Also, reflectivity measurements, together with a fitting procedure based on the transfer matrix formalism, are used to determine the thickness of samples. Excitons are atom-like quasi-particles, formed from a bound electron-hole pair. They follow a Bose-Einstein statistic, so in principle it is possible to achieve an excitonic Bose-Einstein condensate. Time resolved photoluminescence measurements were performed over an extensive range of lattice temperatures and carrier concentrations, in order to determine the fraction of excitons formed from the electron-hole plasma in a quantum well, after non-resonant excitation. The experimental spectra were compared to a pure plasma calculation first, then excitons were taken into account-The highest fraction of formed excitons is found for low temperatures and intermediate carrier densities. This fraction is found to be very small, and this has clear implications on the excitonic Bose-Einstein condensation studies. The photoluminescence emitted left and right from a quantum well is interfered in a modified Mach-Zender interferometer. It is shown that the light emitted on the two paths will interfere for a V-shape geometry and will not for any other paths. A structure formed by placing a quantum well in a field antinode of a resonant planar microcavity exhibits normal mode coupling: splitting of the resonance spectral line. For the case of resonant excitation, a third peak appears at higher excitation levels. The coherence properties of the photoluminescence from a normal-mode-coupling microcavity are studied using another version of the Mach-Zender interferometer. The degree of coherence measured in this way depends greatly on the pump wavelength and intensity, ranging from zero to 0.8. However, direct observation of the emission speckle shows significant coherence in all cases. The difference is explained by the different methods used to evaluate the coherence. The strong coupling between a quantum dot and a photonic crystal nanocavity is investigated by observation of photoluminescence. A new method of tunning the cavity wavelength by deposition of a thin film of solid Xenon on all the surfaces of the sample is presented. The method allows the scanning of the cavity wavelength with about 5 nm without a decrease in the quality factor and without changing the temperature. Finally, an extensive study of the quality factors of quantum dot photonic crystal nanocavities is presented. The role of the quantum dot ensemble absorption is investigated. At higher excitation levels, lasing is observed and discussed.

Mosor, Sorin

381

Inward transport of a toroidally confined plasma subject to strong radial electric fields  

NASA Technical Reports Server (NTRS)

Digitally implemented spectral analysis techniques were used to investigate the frequency-dependent fluctuation-induced particle transport across a toroidal magnetic field. When the electric field pointed radially inward, the transport was inward and a significant enhancement of the plasma density and confinement time resulted.

Roth, J. R.; Krawczonek, W. M.; Powers, E. J.; Hong, J.; Kim, Y. H.

1977-01-01

382

Morphology and composition of pyrotechnic residues formed at different levels of confinement  

Microsoft Academic Search

Post explosion residues (PER) are residues from pyrotechnic compositions or explosives that are generated during an explosion. In the recent past SEM\\/EDX was used several times to analyze PER from pyrotechnic compositions. The results from these studies suggest that there might be a difference in morphology and composition of pyrotechnic residues formed at different levels of confinement. Also because of

Erwin Vermeij; Willem Duvalois; Rutger Webb; Mattijs Koeberg

2009-01-01

383

Applications of group-invariant analytic solutions to inertial confinement fusion  

SciTech Connect

Analytic solutions to 1-,2-, and 3-D hydrodynamics are presented which can be applied to specific aspects of Inertial Confinement Fusion target evolutions. These solutions include drive source time profiles for 1-D isentropic implosions, 2-D P{sub 2} asymmetric compressions, 1- and 2-D solutions for the stagnation phase of implosions, and a 3-D spinning (mixing) solution.

Coggeshall, S.V.

1992-01-01

384

Inertial Confinement Fusion quarterly report, April--June 1995. Volume 5, No. 3  

SciTech Connect

The ICF Quarterly Reports is published four times each fiscal year by the Inertial Confinement Fusion Program at the Lawrence Livermore National Laboratory. The journal reports selected current research within the ICF Program. Major areas of investigation presented here include fusion target theory and design, target fabrication, target experiments, and laser and optical science and technology.

NONE

1995-12-31

385

Valence photoionization of noble-gas atoms confined in the fullerene C60  

NASA Astrophysics Data System (ADS)

A systematic study and comparison of the photoionization cross sections of the outer and inner shells of the noble-gas atoms He, Ne, Ar, Kr, and Xe confined endohedrally inside a C60 molecule are calculated by employing a time-dependent local-density-approximation formulation. Confinement resonances are found to be a general feature of these cross sections and dramatic interchannel coupling effects, significantly increasing the atomic cross sections, are exhibited in all cases in the vicinity of the C60 plasmons. Hybridization effects, the mixing of the atomic and cage bound-state wave functions, are also found, but no systematics of the hybridization present themselves.

Javani, Mohammad H.; Chakraborty, Himadri S.; Manson, Steven T.

2014-05-01

386

Improving Stability and Confinement of Slowly Rotating Tokamak Plasmas Using Static Nonaxisymmetric Magnetic Fields  

NASA Astrophysics Data System (ADS)

A high-confinement regime without edge localized mode instabilities (QH-mode) has been demonstrated for the first time in tokamak plasmas with near-zero rotation and zero-net neutral beam injected torque. Edge rotation shear required for QH-mode operation is generated by the counter-Ip torque driven, through neoclassical toroidal viscosity, by externally applied static, nonaxisymmetric, nonresonant magnetic fields. In this regime, the nonresonant magnetic fields also provide improved resilience to locked modes. Furthermore, the energy confinement improves with higher plasma pressure and slower rotation. The reduction in energy transport is correlated with a reduction in turbulent fluctuations.

Garofalo, A. M.; Burrell, K. H.; Osborne, T. H.; Schaffer, M. J.; Snyder, P. B.; Solomon, W. M.; Lanctot, M. J.; Reimerdes, H.; Rhodes, T. L.; Schmitz, L.; McKee, G. R.; Yan, Z.

2010-11-01

387

ELMy H-mode confinement and threshold power by low hybrid wave on the EAST tokamak  

NASA Astrophysics Data System (ADS)

Stationary type-III ELMy H-mode plasmas were achieved on Experimental Advanced Superconducting Tokamak (EAST) by low hybrid wave in 2010. The threshold power increases with plasma density, and a significant reduction in the H-mode occurs by decreasing the distance between the X-point and the strike point at the outside lower divertor on EAST. A series of statistics for the H-mode confinement such as the dependence of energy confinement time (?E) on plasma density and loss power is experimentally studied in detail.

Liu, Z. X.; Gao, X.; Zhang, W. Y.; Li, J. G.; Gong, X. Z.; Jie, Y. X.; Zhang, S. B.; Zeng, L.; Shi, N.; the EAST Team

2012-08-01

388

Transient dynamics of confined liquid drops in a uniform electric field  

NASA Astrophysics Data System (ADS)

We analyze the effect of confinement on the transient dynamics of liquid drops, suspended in another immiscible liquid medium, under the influence of an externally applied uniform dc electric field. For our analysis, we adhere to an analytical framework conforming to a Newtonian-leaky-dielectric liquid model in the Stokes flow regime, under the small deformation approximation. We characterize the transient relaxation of the drop shape towards its asymptotic configuration, attributed by the combined confluence of the charge-relaxation time scale and the intrinsic shape-relaxation time scale. While the former appears due to the charge accumulation process on the drop surface over a finite interval of time, the genesis of the latter is found to be intrinsic to the hydrodynamic situation under consideration. In an unbounded condition, the intrinsic shape-relaxation time scale is strongly governed by the viscosity ratio, defined as the ratio of dynamic viscosities of the droplet and the background liquid. However, when the wall effects are brought into consideration, the combined influence of the relative extent of the confinement and the intrinsic viscosity effects, acting in tandem, alter this time scale in a rather complicated and nontrivial manner. We reveal that the presence of confinement may dramatically increase the effective viscosity ratio that could have otherwise been required in an unconfined domain to realize identical time-relaxation characteristics. We also bring out the alterations in the streamline patterns because of the combinations of transient and confinement effects. Thus, our results reveal that the extent of fluidic confinement may provide an elegant alternative towards manipulating the transient dynamics of liquid drops in the presence of an externally applied electric field, bearing far-ranging consequences towards the design and functionalities of several modern-day microfluidic applications.

Mandal, Shubhadeep; Chaudhury, Kaustav; Chakraborty, Suman

2014-05-01

389

Dynamics of two-dimensional monolayer water confined in hydrophobic and charged environments  

NASA Astrophysics Data System (ADS)

We perform molecular dynamics simulations to study the effect of charged surfaces on the intermediate and long time dynamics of water in nanoconfinements. Here, we use the transferable interaction potential with five points (TIP5P) model of a water molecule confined in both hydrophobic and charged surfaces. For a single molecular layer of water between the surfaces, we find that the temperature dependence of the lateral diffusion constant of water up to very high temperatures remains Arrhenius with a high activation energy. In case of charged surfaces, however, the dynamics of water in the intermediate time regime is drastically modified presumably due to the transient coupling of dipoles of water molecules with electric field fluctuations induced by charges on the confining surfaces. Specifically, the lateral mean square displacements display a distinct super-diffusive behavior at intermediate time scale, defined as the time scale between ballistic and diffusive regimes. This change in the intermediate time-scale dynamics in the charged confinement leads to the enhancement of long-time dynamics as reflected in increasing diffusion constant. We introduce a simple model for a possible explanation of the super-diffusive behavior and find it to be in good agreement with our simulation results. Furthermore, we find that confinement and the surface polarity enhance the low frequency vibration in confinement compared to bulk water. By introducing a new effective length scale of coupling between translational and orientational motions, we find that the length scale increases with the increasing strength of the surface polarity. Further, we calculate the correlation between the diffusion constant and the excess entropy and find a disordering effect of polar surfaces on the structure of water. Finally, we find that the empirical relation between the diffusion constant and the excess entropy holds for a monolayer of water in nanoconfinement.

Kumar, Pradeep; Han, Sungho

2012-09-01

390

Dynamics of two-dimensional monolayer water confined in hydrophobic and charged environments.  

PubMed

We perform molecular dynamics simulations to study the effect of charged surfaces on the intermediate and long time dynamics of water in nanoconfinements. Here, we use the transferable interaction potential with five points (TIP5P) model of a water molecule confined in both hydrophobic and charged surfaces. For a single molecular layer of water between the surfaces, we find that the temperature dependence of the lateral diffusion constant of water up to very high temperatures remains Arrhenius with a high activation energy. In case of charged surfaces, however, the dynamics of water in the intermediate time regime is drastically modified presumably due to the transient coupling of dipoles of water molecules with electric field fluctuations induced by charges on the confining surfaces. Specifically, the lateral mean square displacements display a distinct super-diffusive behavior at intermediate time scale, defined as the time scale between ballistic and diffusive regimes. This change in the intermediate time-scale dynamics in the charged confinement leads to the enhancement of long-time dynamics as reflected in increasing diffusion constant. We introduce a simple model for a possible explanation of the super-diffusive behavior and find it to be in good agreement with our simulation results. Furthermore, we find that confinement and the surface polarity enhance the low frequency vibration in confinement compared to bulk water. By introducing a new effective length scale of coupling between translational and orientational motions, we find that the length scale increases with the increasing strength of the surface polarity. Further, we calculate the correlation between the diffusion constant and the excess entropy and find a disordering effect of polar surfaces on the structure of water. Finally, we find that the empirical relation between the diffusion constant and the excess entropy holds for a monolayer of water in nanoconfinement. PMID:22998274

Kumar, Pradeep; Han, Sungho

2012-09-21

391

Dynamics of laser-blow-off induced Li plume in confined geometry  

SciTech Connect

Dynamics of Li plasma plume created by laser-blow-off technique in air ambient is reported. Plasma plume dynamics and its optical emission are investigated in planar and confined geometries using time resolved shadowgraph imaging and optical emission spectroscopy. Significant differences in the plasma characteristics in confined geometry are quantitatively investigated by comparing the plasma parameters (temperature and density) in free expansion and confined geometry configurations. Dynamics and physical parameters of the primary as well as the reflected shock waves (in confined geometry) and their interactions with expanding plasma are briefly addressed. A large enhancement in the emission intensities of Li I 610.3 nm (2p {sup 2}P{sub 1/2,3/2}? 3d {sup 2}P{sub 3/2,5/2}) and 670.8 nm (2s {sup 2}S{sub 1/2}? 2p {sup 2}P{sub 1/2,3/2}) is correlated with the shock wave dynamics in the two geometries. Strong self reversal in the neutral emission infers an increase in the population density of neutrals within the confined plasma plume.

Kumar, Bhupesh; Singh, R K; Kumar, Ajai [Institute for Plasma Research, Bhat, Gandhinagar-382 428 (India)] [Institute for Plasma Research, Bhat, Gandhinagar-382 428 (India)

2013-08-15

392

Dynamics of laser-blow-off induced Li plume in confined geometry  

NASA Astrophysics Data System (ADS)

Dynamics of Li plasma plume created by laser-blow-off technique in air ambient is reported. Plasma plume dynamics and its optical emission are investigated in planar and confined geometries using time resolved shadowgraph imaging and optical emission spectroscopy. Significant differences in the plasma characteristics in confined geometry are quantitatively investigated by comparing the plasma parameters (temperature and density) in free expansion and confined geometry configurations. Dynamics and physical parameters of the primary as well as the reflected shock waves (in confined geometry) and their interactions with expanding plasma are briefly addressed. A large enhancement in the emission intensities of Li I 610.3 nm (2p 2P1/2, 3/2 <-- 3d 2P3/2, 5/2) and 670.8 nm (2s 2S1/2 <-- 2p 2P1/2, 3/2) is correlated with the shock wave dynamics in the two geometries. Strong self reversal in the neutral emission infers an increase in the population density of neutrals within the confined plasma plume.

Kumar, Bhupesh; Singh, R. K.; Kumar, Ajai

2013-08-01

393

Topological superfluids confined in a nanoscale slab geometry  

NASA Astrophysics Data System (ADS)

Nanofluidic samples of superfluid ^3He provide a route to explore odd-parity topological superfluids and their surface, edge and defect-bound excitations under well controlled conditions. We have cooled superfluid ^3He confined in a precisely defined nano-fabricated cavity to well below 1 mK for the first time. We fingerprint the order parameter by nuclear magnetic resonance, exploiting a SQUID NMR spectrometer of exquisite sensitivity. We demonstrate that dimensional confinement, at length scales comparable to the superfluid Cooper-pair diameter, has a profound influence on the superfluid order of ^3He. The chiral A-phase is stabilized at low pressures, in a cavity of height 650 nm. At higher pressures we observe ^3He-B with a surface induced planar distortion. ^3He-B is a time-reversal invariant topological superfluid, supporting gapless Majorana surface states. In the presence of the small symmetry breaking NMR static magnetic field we observe two possible B-phase states of the order parameter manifold, which can coexist as domains. Non-linear NMR on these states enables a measurement of the surface induced planar distortion, which determines the spectral weight of the surface excitations. The expected structure of the domain walls is such that, at the cavity surface, the line separating the two domains is predicted to host fermion zero modes, protected by symmetry and topology. Increasing confinement should stabilize new p-wave superfluid states of matter, such as the quasi-2D gapped A phase, which breaks time reversal symmetry, has a protected chiral edge mode, and may host half-quantum vortices with a Majorana zero-mode at the core. We discuss experimental progress toward this phase, through measurements on a 100 nm cavity. On the other hand, a cavity height of 1000 nm may stabilize a novel ``striped'' superfluid with spatially modulated order parameter.[4pt] In collaboration with L.V. Levitin, R.G. Bennett, A.J. Casey, B. Cowan, J. Parpia, E.V. Surovtsev

Saunders, John

2013-03-01

394

Thermodynamic Properties of Alkanes in Confined Geometries  

NASA Astrophysics Data System (ADS)

Reported are the results of two related investigations. The first is a theoretical study of the thermal response of a model differential scanning calorimeter (DSC) yielding insights into proper techniques for sample preparation, instrument calibration, and interpretation of phase transition data. This is followed by a calorimetric study of the melting and freezing behavior of cyclohexane ( rm C_6H_{12}), cyclooctane (rm C_8H_{16}), and n-octane (rm C_8H_{18 }), confined within the pore spaces of a series of porous silica glasses with mean pore radii r between 4.1 +/- 0.3 and 64 +/- 5 nm. The melting and freezing temperatures and latent heats of the pore alkanes were found to be increasingly depressed from the bulk values with decreasing pore size r. Unlike previous studies of phase transitions of confined organic substances, we have observed melting temperature depressions which are stronger than r^{ -1}. These temperature depressions can be expressed by the empirical cluster equation rm T_{m} = T_{o} - A/(r - r_{rm o}). The latent heats were found to vary approximately linearly with the inverse pore radius. The transition data from incompletely filled pores indicate that the alkanes are not layering the pore walls evenly, but are gathering as plugs at the pore necks. Studies using glasses in which the silica surface was modified using a standard derivatization technique suggest that the replacement ligands are not forming a complete monolayer. We have also observed cyclooctane supercools by 10-15 K below the expected freezing point, both in bulk and confined within the porous glass.

Sheehan, Joseph F., III

395

Size-dependent enhancement of nonlinear optical susceptibilities due to confined excitons in CuBr nanocrystals  

Microsoft Academic Search

We have investigated the third-order nonlinearity on resonance with the confined exciton level in CuBr nanocrystals with radii in the range 2.7-42 nm embedded in glass by means of degenerate four-wave mixing, time-resolved luminescence, and resonant luminescence measurements. The third-order optical susceptibility chi(3) exhibits resonant behaviors at Z12 and Z3 excitons, which are weakly confined in nanocrystals. The figure of

Yingli Li; Masaki Takata; Arao Nakamura

1998-01-01

396

Effects of strength training, using a gravity-independent exercise system, performed during 110 days of simulated space station confinement  

Microsoft Academic Search

The efficacy of a resistance exercise paradigm, using a gravity-independent flywheel principle, was examined in four men subjected\\u000a to 110 days of confinement (simulation of flight of international crew on space station; SFINCSS-99). Subjects performed six\\u000a upper- and lower-body exercises (calf raise, squat, back extension, seated row, lateral shoulder raise, biceps curl) 2–3 times\\u000a weekly during the confinement. The exercise regimen

Björn A. Alkner; Hans E. Berg; Inessa Kozlovskaya; Dimitri Sayenko; Per A. Tesch

2003-01-01

397

Mechanisms for selective radial dispersion of microparticles in the transitional region of a confined turbulent round jet  

Microsoft Academic Search

The dispersion of particles of different diameters in a confined turbulent round jet is dominated by the local interactions between dispersed phase and large-scale, time dependent flow structures which populate the near-field of the jet. In this work, we address first the problem of identifying the flow structures which form in a three-dimensional, turbulent confined round jet, considering also the

Fabio Sbrizzai; Roberto Verzicco; Marco F. Pidria; Alfredo Soldati

2004-01-01

398

Self-Induced Oscillation for Electron-Hole Pair Confined in Quantum Dot  

SciTech Connect

We study the time-dependent (TD) phenomena of the electron-hole or electron-electron pair confined in the square quantum dot (SQD) system by computationally solving TD Schroedinger equation under the unrestricted Hartree-Fock (UHF) approach. A typical vacillation is found both in the electron and hole when the charged pair is strongly confined in the SQD while the charged particles have initially the same orbital symmetry. The FFT analysis elucidates that the transition matrix element due to the coulomb interaction involves the eigen frequency {omega} being equal to the excitation energy when the resonative vacillation appears. Thus, Coulomb potential has a potential to cause the self-induced ''Rabi'' oscillation when the charged-particle pair is confined only in the QD.

Tagawa, Tomoki; Tsubaki, Atsushi; Ishizuki, Masamu; Takeda, Kyozaburo [Department of Electrical Engineering and Bioscience, Waseda University, Tokyo 169-8555 (Japan)

2011-12-23

399

PTRANSP study of energy confinement associated with toroidal rotation in tokamak discharges  

NASA Astrophysics Data System (ADS)

PTRANSP integrated modeling simulations are carried out for existing tokamak devices and ITER in order to study the effects of toroidal rotation on the thermal energy confinement in H-mode discharges. These simulations include self-consistent computation of toroidal momentum transport, thermal transport, and particle transport. The toroidal rotation frequency is evolved by balancing momentum diffusion and convection against the source of neutral beam torque. The toroidal angular momentum diffusion coefficients are computed using the GLF23 model or the new Weiland model. Objectives of this work include examining the parametric dependence of the simulated energy and momentum confinement times as a function of the beam driven torque density. PTRANSP simulations indicate that the flow shear driven by toroidal rotation could increase the fusion performance of ITER. It is shown that the improvement in thermal energy confinement depends on the choice of the edge boundary condition for the toroidal rotation frequency.

Halpern, F. D.; Kritz, A. H.; Bateman, G.; Pankin, A. Y.; Rafiq, T.; McCune, D. C.; Budny, R. V.

2008-11-01

400

Analysis of reflected blast wave pressure profiles in a confined room  

NASA Astrophysics Data System (ADS)

To understand the blast effects of confined explosions, it is necessary to study the characteristic parameters of the blast wave in terms of overpressure, impulse and arrival time. In a previous study, experiments were performed using two different scales of a pyrotechnic workshop. The main purpose of these experiments was to compare the TNT equivalent for solid and gaseous explosives in terms of mass to define a TNT equivalent in a reflection field and to validate the similitude between real and small scales. To study the interactions and propagations of the reflected shock waves, the present study was conducted by progressively building a confined volume around the charge. In this way, the influence of each wall and the origins of the reflected shock waves can be determined. The purpose of this paper is to report the blast wave interactions that resulted from the detonation of a stoichiometric propane-oxygen mixture in a confined room.

Sauvan, P. E.; Sochet, I.; Trélat, S.

2012-05-01

401

Momentum Confinement on DIII-D with Low Net Neutral Beam Torque  

NASA Astrophysics Data System (ADS)

Momentum confinement was investigated in ELMing H-mode plasmas with elevated qmin. Torque scans were performed at constant ?N, and the rotation profile was measured using charge exchange recombination (CER) spectroscopy. Studies of the mechanical angular momentum in the plasma show a non-uniform response to the applied neutral beam torque, resulting in a torque dependence of the momentum confinement time. Under nominally balanced neutral beam injection, the plasma maintains a significant rotation in the same direction as the plasma current (co-rotation). The intrinsic rotation can be understood as being due to an offset in the applied torque (i.e. an ``anomalous torque''). Analysis including the effect of anomalous fast ion diffusion shows that the anomalous torque appears to have a magnitude comparable to one neutral beam source, with the torque peaked at the edge of the plasma. Meaningful studies of momentum confinement must account for this intrinsic rotation/anomalous torque.

Solomon, W. M.; Budny, R. V.; Mikkelsen, D.; Nazikian, R.; Scott, S. D.; Zarnstorff, M. C.; Burrell, K. H.; Degrassie, J. S.; Groebner, R. J.; Kinsey, J. E.; Petty, C. C.

2007-11-01

402

Graviton confinement inside hypermonopoles of any dimension  

NASA Astrophysics Data System (ADS)

We show the generic existence of metastable massive gravitons in the four-dimensional core of self-gravitating hypermonopoles in any number of infinite-volume extra-dimensions. Confinement is observed for Higgs and gauge bosons couplings of the order unity. Provided these resonances are light enough, they may realise the Dvali-Gabadadze-Porrati mechanism by inducing a four-dimensional gravity law on some intermediate length scales. The effective four-dimensional Planck mass is shown to be proportional to a negative power of the graviton mass. As a result, requiring gravity to be four-dimensional on cosmological length scales may solve the mass hierarchy problem.

Murray, Seán; Ringeval, Christophe; Zonetti, Simone

2010-09-01

403

Strongly Anisotropic Dielectric Response of Confined Water  

NASA Astrophysics Data System (ADS)

We carried out atomistic simulations of water within hydrophobic surfaces, which revealed remarkable modifications of the dynamics and dielectric relaxation of the liquid under confinement. We found that dipolar fluctuations are modified by the presence of surfaces up to strikingly large distances, i.e., tens of nanometers. Fluctuations are suppressed by approximately an order of magnitude in the z direction, perpendicular to the interface, and are enhanced in the x-y plane, giving rise to strong anisotropies in the components of the dielectric response. Our findings are consistent with recent terahertz and ultrafast infrared pump-probe spectroscopy experiments. Work supported by DOE-CMSN DE-SC0005180.

Zhang, Cui; Gygi, Francois; Galli, Giulia

2013-03-01

404

Morphogenesis of membrane invaginations in spherical confinement  

NASA Astrophysics Data System (ADS)

We study the morphology of a fluid membrane in spherical confinement. When the area of the membrane is slightly larger than the area of the outer container, a single axisymmetric invagination is observed. For higher area, self-contact occurs: the invagination breaks symmetry and deforms into an ellipsoid-like shape connected to its outer part via a small slit. For even higher areas, a second invagination forms inside the original invagination. The folding patterns observed could constitute basic building blocks in the morphogenesis of biological tissues and organelles.

Kahraman, O.; Stoop, N.; Müller, M. M.

2012-03-01

405

Vortex distribution in a confining potential  

NASA Astrophysics Data System (ADS)

We study a model of interacting vortices in a type II superconductor. In the weak coupling limit, we constructed a mean-field theory which allows us to accurately calculate the vortex density distribution inside a confining potential. In the strong coupling limit, the correlations between the particles become important and the mean-field theory fails. Contrary to recent suggestions, this does not imply failure of the Boltzmann-Gibbs statistical mechanics, as we clearly demonstrate by comparing the results of molecular dynamics and Monte Carlo simulations.

Girotto, Matheus; dos Santos, Alexandre P.; Levin, Yan

2013-09-01

406

Crystalline multilayers of the confined Yukawa system  

NASA Astrophysics Data System (ADS)

The phase diagram of Yukawa particles confined between two parallel hard walls is calculated at zero temperature beyond the bilayer regime by lattice-sum-minimization. Tuning the screening, a rich phase behavior is found in the regime bounded by stable two triangular layers and three square layers. In this regime, alternating prism phases with square and triangular basis, structures derived from a hcp bulk lattice, and a structure with two outer layers and two inner staggered rectangular layers, reminiscent of a Belgian waffle iron, are stable. These structures are verifiable in experiments on charged colloidal suspensions and dusty plasma sheets.

O?uz, E. C.; Messina, R.; Löwen, H.

2009-04-01

407

Electron transport in confined oxide nanowires  

NASA Astrophysics Data System (ADS)

The invention of conductive AFM lithography at the LaAlO3/SrTiO3 interface enables the creation of clean inter-connected oxide nanowires and artificially engineered tunnel barriers. Here we create an oxide nanowire that is confined by two tunnel barriers using this technique. Two terminal and four terminal transport studies reveal transitions among Cooper pair tunneling, Coulomb blockade and Fabry-Perot inteference that can be tuned by side gate voltages and external magnetic field. Our results indicate the presence of long-range coherence in LaAlO3/SrTiO3 nanowires.

Cheng, Guanglei; Tomczyk, Michelle; Lu, Shicheng; Huang, Mengchen; Veazey, Josh; Irvin, Patrick; Eom, Chang-Beom; Levy, Jeremy

2013-03-01

408

Micromachining of inertial confinement fusion targets  

SciTech Connect

Many experiments conducted on today`s largest inertial confinement fusion drive lasers require target components with sub-millimeter dimensions, precisions of a micron or less and surface finishes measured in nanometers. For metal and plastic, techniques using direct machining with diamond tools have been developed that yield the desired parts. New techniques that will be discussed include the quick-flip locator, a magnetically held kinematic mount that has allowed the direct machining of millimeter-sized beryllium hemishells whose inside and outside surface are concentric to within 0.25 micron, and an electronic version of a tracer lathe which has produced precise azimuthal variations of less than a micron.

Gobby, P.L.; Salzer, L.J.; Day, R.D. [and others

1996-12-31

409

Isolation and confinement - Considerations for colonization  

NASA Technical Reports Server (NTRS)

This paper discusses three types of isolation (sensory/perceptual, temporal, and social) that could adversely affect mankind in space. The literature dealing with laboratory and field experiments relevant to these areas is summarized and suggestions are given for dealing with these problems within the space colony community. Also, consideration is given to the potential effects of physical confinement and the need for usable space. Finally, a modification of Maslow's hierarchy of needs is proposed as a theoretical framework to understand and investigate mankind's psychological needs in space.

Akins, F. R.

1978-01-01

410

Equilibrium of an elastically confined liquid drop  

NASA Astrophysics Data System (ADS)

When a liquid drop is confined between an elastic plate and a rigid substrate, it spreads spontaneously due to the effects of interfacial forces, eventually reaching an equilibrium shape determined by the balance between elastic and capillary effects. We provide an analytical theory for the static shape of the sheet and the extent of liquid spreading and show that our experiments are quantitatively consistent with the theory. The theory is relevant for the first step of painting when a brush is brought down on to canvas. More mundanely, it allows us to understand the stiction of microcantilevers to wafer substrates occurring in microelectromechanical fabrication processes.

Kwon, Hyuk-Min; Kim, Ho-Young; Puëll, Jérôme; Mahadevan, L.

2008-05-01

411

Molecular Understanding of Diffusion in Confinement  

NASA Astrophysics Data System (ADS)

We introduce a computational method to directly relate diffusivities to the microscopic behavior of the adsorbed molecules. We apply this method to gases in an MFI-type molecular sieve, the reference system in this field. Transitions in the number and nature of adsorption sites result in temporary local increases in the diffusion. This occurs at different loadings in each of the x, y, and z directions, giving rise to the complex loading behavior found experimentally. Our method can be applied to any adsorbent-adsorbate system, and provides a fundamental understanding of diffusion in confinement on a molecular level.

Beerdsen, E.; Dubbeldam, D.; Smit, B.

2005-10-01

412

Diamond Ablators for Inertial Confinement Fusion  

SciTech Connect

Diamond has a unique combination of physical properties for the inertial confinement fusion ablator application, such as appropriate optical properties, high atomic density, high yield strength, and high thermal conductivity. Here, we present a feasible concept to fabricate diamond ablator shells. The fabrication of diamond capsules is a multi-step process, which involves diamond chemical vapor deposition on silicon mandrels followed by polishing, microfabrication of holes, and removing of the silicon mandrel by an etch process. We also discuss the pros and cons of coarse-grained optical quality and nanocrystalline chemical vapor deposition diamond films for the ablator application.

Biener, J; Mirkarimi, P B; Tringe, J W; Baker, S L; Wang, Y M; Kucheyev, S O; Teslich, N E; Wu, K J; Hamza, A V; Wild, C; Woerner, E; Koidl, P; Bruehne, K; Fecht, H

2005-06-21

413

Microwave Reflectometry for Magnetically Confined Plasmas  

SciTech Connect

This paper is about microwave reflectometry -- a radar technique for plasma density measurements using the reflection of electromagnetic waves by a plasma cutoff. Both the theoretical foundations of reflectometry and its practical application to the study of magnetically confined plasmas are reviewed in this paper. In particular, the role of short-scale density fluctuations is discussed at length, both as a unique diagnostic tool for turbulence studies in thermonuclear plasmas and for the deleterious effects that fluctuations may have on the measurement of the average plasma density with microwave reflectometry.

Mazzucato, E.

1998-02-01

414

Vortex distribution in a confining potential.  

PubMed

We study a model of interacting vortices in a type II superconductor. In the weak coupling limit, we constructed a mean-field theory which allows us to accurately calculate the vortex density distribution inside a confining potential. In the strong coupling limit, the correlations between the particles become important and the mean-field theory fails. Contrary to recent suggestions, this does not imply failure of the Boltzmann-Gibbs statistical mechanics, as we clearly demonstrate by comparing the results of molecular dynamics and Monte Carlo simulations. PMID:24125224

Girotto, Matheus; Dos Santos, Alexandre P; Levin, Yan

2013-09-01

415

Anomalous diffusion in confined turbulent convection.  

PubMed

Turbulent convection in quasi-one-dimensional geometry is studied by means of high-resolution direct numerical simulations within the framework of Rayleigh-Taylor turbulence. Geometrical confinement has dramatic effects on the dynamics of the turbulent flow, inducing a transition from superdiffusive to subdiffusive evolution of the mixing layer and arresting the growth of kinetic energy. A nonlinear diffusion model is shown to reproduce accurately the above phenomenology. The model is used to predict, without free parameters, the spatiotemporal evolution of the heat flux profile and the dependence of the Nusselt number on the Rayleigh number. PMID:23005221

Boffetta, G; De Lillo, F; Musacchio, S

2012-06-01

416

Plasma confinement by circularly polarized electromagnetic field in toroidal geometry  

SciTech Connect

A novel plasma confinement concept based on plasma confinement by electromagnetic pressure of circularly polarized electromagnetic fields is proposed. Practical implementation of this concept in a toroidal device is suggested. In this concept the confining field frequency is in the lower range such that the size of the device is much smaller than the vacuum wavelength. Most of the previous radio-frequency (rf) confinement concepts of unmagnetized plasma were related to confinement in rf cavities which operated at high frequency for which the size of the cavity is comparable to the wavelength. Operation at lower frequencies simplifies rf design, reduces Ohmic losses in the conducting walls and probably makes application of superconductors for wall materials more feasible. It is demonstrated that circular (or nearly circular) polarization of the electromagnetic field is required for confinement from both the equilibrium and stability considerations. Numerical analysis of plasma confinement for magnetohydrodynamic plasma model in two-dimensional toroidal geometry is performed. Within this model plasma is confined by the applied rf fields and its equilibrium is stable. Technically feasible compact and medium size toroidal plasma confinement devices based on this concept are proposed. Application of this approach to the fusion reactor requires use of superconducting materials for the toroidal shell to reduce the Ohmic losses. Further theoretical and experimental studies are required for a more reliable conclusion about the attractiveness of this plasma confinement concept.

Svidzinski, Vladimir A. [University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); and Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2007-10-15

417

Nonequilibrium dynamics and ultraslow relaxation of confined DNA during viral packaging.  

PubMed

Many viruses use molecular motors that generate large forces to package DNA to near-crystalline densities inside preformed viral proheads. Besides being a key step in viral assembly, this process is of interest as a model for understanding the physics of charged polymers under tight 3D confinement. A large number of theoretical studies have modeled DNA packaging, and the nature of the molecular dynamics and the forces resisting the tight confinement is a subject of wide debate. Here, we directly measure the packaging of single DNA molecules in bacteriophage phi29 with optical tweezers. Using a new technique in which we stall the motor and restart it after increasing waiting periods, we show that the DNA undergoes nonequilibrium conformational dynamics during packaging. We show that the relaxation time of the confined DNA is >10 min, which is longer than the time to package the viral genome and 60,000 times longer than that of the unconfined DNA in solution. Thus, the confined DNA molecule becomes kinetically constrained on the timescale of packaging, exhibiting glassy dynamics, which slows the motor, causes significant heterogeneity in packaging rates of individual viruses, and explains the frequent pausing observed in DNA translocation. These results support several recent hypotheses proposed based on polymer dynamics simulations and show that packaging cannot be fully understood by quasistatic thermodynamic models. PMID:24912187

Berndsen, Zachary T; Keller, Nicholas; Grimes, Shelley; Jardine, Paul J; Smith, Douglas E

2014-06-10

418

Beta and confinement experiments on Doublet III with high-power neutral beam heating  

SciTech Connect

Beta and energy confinement experiments with up to 7.5 MW of neutral beam heating power injected into both limited and diverted equilibria are discussed. We have studied beta limits at both the low q (high ..beta../sub T/, low ..beta../sub p/) and high q (low ..beta../sub T/, high ..beta../sub p/) ends of the ideal MHD n = infinity ballooning limit curve. Discharges which disruptively terminate have not clearly exceeded predicted ballooning limits but have been within 20% of marginal stability for ideal ballooning modes. Energy confinement time studies show that tau/sub E/ scales linearly with plasma current and deteriorates with beam power, although there are indications that tau/sub E/ may be approaching a new asymptotic value at high power levels. We find that diverted equilibria afford up to a factor of 2 greater confinement times at high power levels. Transport analysis indicates that electron conduction is the major heat loss mechanism and that the electron conductivity is generally 2--3 times lower in divertor discharges compared to limiter discharges with comparable parameters. We observe a strong correlation between improved confinement and the separation between the limiter and separatrix flux surface.

DeBoo, J.C.; Armentrout, C.J.; Baur, J.F.; Blau, F.P.; Bramson, G.; Burrell, K.H.; Chase, R.P.; Ejima, S.; Fairbanks, E.S.; Groebner, R.

1985-01-01

419

Beta and confinement experiments in Doublet III with high power neutral beam heating  

SciTech Connect

Beta and energy confinement experiments with up to 7.5 MW of neutral beam heating power injected into both limited and diverted equilibria are discussed. We have studied beta limits at both the low q (high ..beta../sub T/, low ..beta../sub p/) and high q (low ..beta../sub T/, high ..beta../sub p/) ends of the ideal MHD n = infinity ballooning limit curve. Discharges which disruptively terminate have not clearly exceeded predicted ballooning limits but have been within 20% of marginal stability for ideal ballooning modes. Energy confinement time studies show that tau/sub E/ scales linearly with plasma current and deteriorates with beam power, although there are indications that tau/sub E/ may be approaching a new asymptotic value at high power levels. We find that diverted equilibria afford up to a factor of two greater confinement times at high power levels. Transport analysis indicates that electron conduction is the major heat loss mechanism and that the electron conductivity is generally 2 to 3 times lower in divertor discharges compared to limiter discharges with comparable parameters. We observe a strong correlation between improved confinement and the separation between the limiter and separatrix flux surface.

DeBoo, J.C.; Armentrout, C.J.; Baur, J.F.; Blau, F.P.; Bramson, G.; Burrell, K.H.; Chase, R.P.; Ejima, S.; Fairbanks, E.S.; Groebner, R.

1984-06-01

420

The QCD Confinement Transition: Hadron Formation  

NASA Astrophysics Data System (ADS)

This document is part of Volume 23 `Relativistic Heavy Ion Physics' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms'. It contains the Section `4.3 The QCD Confinement Transition: Hadron Formation' of the Chapter `4 The Hadron-Parton Phase Transition' with the content: 4.3 The QCD Confinement Transition: Hadron Formation 4.3.1 Introduction 4.3.2 The Statistical Hadronization Model 4.3.2.1 Localized States 4.3.2.2 The Formalism: Basics 4.3.2.3 Rates of Multiparticle Channels 4.3.2.4 Interactions 4.3.2.5 High Energy Collisions 4.3.2.6 Heavy Ion Collisions 4.3.2.7 Strangeness Production 4.3.2.8 Thermalization: How Is It Achieved? 4.3.3 Quark Recombination 4.3.3.1 Parton Fragmentation and Its Limitations 4.3.3.2 The Recombination Formalism 4.3.3.2.1 Basic Theory 4.3.3.2.2 Different Implementations of Instantaneous Recombination 4.3.3.2.3 Dynamical Recombination 4.3.3.3 Connection with other Hadronization Models 4.3.3.4 Experimental Evidence for Recombination 4.3.3.4.1 Hadron Spectra and Ratios 4.3.3.4.2 Elliptic Flow 4.3.4 Summary and conclusions

Becattini, Francesco; Fries, Rainer J.

421

Photopolymerization induced phase ordering in confined regions  

NASA Astrophysics Data System (ADS)

Phase ordering in confined spaces such as stratified layers or columnar domains is of interest for a variety of optical and electronic applications. We have investigated various possibilities of creating photonic crystal structures using an optical wave interference technique subjected to holographic photopolymerization of acrylate systems blended with nematic liquid crystals or conductive crystalline polymers. Melting point depression is known to occur between acrylate monomers and polyethylene oxide or succinonitrile. During the course of photopolymerization, the increase in molecular weight of acrylate and subsequent network formation have shifted the melt point upward above the reaction temperature, which in turn drives PEO to undergo crystallization; hereafter called polymerization-induced crystallization. A variety of conditions have been investigated in the framework of phase field theory for crystallization by coupling with the extended Flory-Huggins theory for polymer blend demixing. The phenomenon of polymerization-induced crystallization during photolithography has been investigated with emphasis on the effect of intensity gradient on the emerging morphology. Additionally, crystallization in confined regions has also been explored.

Kyu, Thein; Matkar, Rushikesh

2005-03-01

422

Deuterium anions in inertial electrostatic confinement devices.  

PubMed

A magnetic deflection-energy analyzer and Faraday trap diagnostic have been used to make measurements of divergent deuterium anion flow in the inertial electrostatic confinement experiment at the University of Wisconsin-Madison (UW-IEC) [J. F. Santarius, G. L. Kulcinski, R. P. Ashley, D. R. Boris, B. B. Cipiti, S. K. Murali, G. R. Piefer, R. F. Radel, I. E. Radel, and A. L. Wehmeyer, Fusion Sci. Technol. 47, 1238 (2005)], a device to confine high-energy light ions in a spherically symmetric electrostatic potential well. Deuterium anion current densities as high as 8.5 microA/cm2 have been measured at the wall of the UW-IEC device, 40 cm from the surface of the device cathode with a detector assembly of admittance area 0.7 cm2. Energy spectra obtained using a magnetic deflection-energy analyzer diagnostic indicate the presence of D2(-), and D- ions produced through thermal electron attachment near the device cathode, as well as D- ions produced via charge-transfer processes between the anode and cathode of the device. PMID:19905231

Boris, D R; Alderson, E; Becerra, G; Donovan, D C; Egle, B; Emmert, G A; Garrison, L; Kulcinski, G L; Santarius, J F; Schuff, C; Zenobia, S J

2009-09-01

423

Invariant Structures in Gauge Theories and Confinement  

NASA Astrophysics Data System (ADS)

The problem of finding all gauge invariants is considered in connection with the problem of confinement. Polylocal gauge tensors are introduced and studied. It is shown (both in physical and pure geometrical approaches) that the path-ordered exponential is the only fundamental bilocal gauge tensor, which means that any irreducible polylocal gauge tensor is built of P-exponentials and local tensors (matter fields). The simplest invariant structures in electrodynamics, chromodynamics and a theory with the gauge group SU(2) are considered separately. As a consequence of gauge invariance any “elementary” charge is accompanied by an external static field located on the integration contour of a P- exponential, i.e. by a string. The Coulomb field is analyzed from this point of view; it is demonstrated that it can also be considered as made of exponential line integrals. In QCD strings can branch—it means that the interquark static field cannot be associated with a simple P-exponential. On the contrary, in pure gluodynamics strings do not branch. Different forms of confinements are briefly reviewed.

Prokhorov, L. V.; Shabanov, S. V.

424

Nanoparticle fabrication by geometrically confined nanosphere lithography  

NASA Astrophysics Data System (ADS)

Arrays of metal nanoparticles, typically gold or silver, exhibit localized surface plasmon resonance, a phenomenon that has many applications, such as chemical and biological sensing. However, fabrication of metal nanoparticle arrays with high uniformity and repeatability, at a reasonable cost, is difficult. Nanosphere lithography (NSL) has been used before to produce inexpensive nanoparticle arrays through the use of monolayers of self-assembled microspheres as a deposition mask. However, control over the size and location of the arrays, as well as uniformity over large areas is poor, thus limiting its use to research purposes. In this paper, a new NSL method, called here geometrically confined NSL (GCNSL), is presented. In GCNSL, microsphere assembly is confined to geometric patterns defined in photoresist, allowing high-precision and large-scale nanoparticle patterning while still remaining low cost. Using this new method, it is demonstrated that 400 nm polystyrene microspheres can be assembled inside of large arrays of photoresist patterns. Results show that optimal microsphere assembly is achieved with long and narrow rectangular photoresist patterns. The combination of microsphere monolayers and photoresist patterns is then used as a deposition mask to produce silver nanoparticles at precise locations on the substrate with high uniformity, repeatability, and quality.

Denomme, Ryan C.; Iyer, Krishna; Kreder, Michael; Smith, Brendan; Nieva, Patricia M.

2013-07-01

425

Fire Risk Analysis for Armenian NPP Confinement  

SciTech Connect

Major fire occurred at Armenian NPP (ANPP) in October 1982 showed that fire-induced initiating events (IE) can have dominant contribution in overall risk of core damage. Probabilistic Safety Assessment study for fire-induced initiating events for ANPP was initiated in 2002. Analysis was performed for compartments fires in which could result in failure of components which are necessary for reactor cold shutdown. Analysis shows that main risk from fire at ANPP is conditioned by fire in cable tunnels 61-64. Meanwhile fire in confinement compartments don't have significant contribution to overall risk of core damage. The exception is so called 'confinement valves compartment' (room no.A-013/2) fire (more than 7.5% of CDF) in which fire could result in the loss of coolant accident with unavailability of primary makeup system, which directly leads to core damage. Detailed analysis of this problem that is common for typical WWER-440/230 reactors with no hermetic MCPs and recommendations for solution are presented in this paper. (authors)

Poghosyan, Shahen; Malkhasyan, Albert; Bznuni, Surik; Amirjanyan, Armen [Armenian Nuclear Regulatory Authority - Armgosatomnadzor (Armenia)

2006-07-01

426

Beyond fusion, annihilation reactions of confined hydrogen  

NASA Astrophysics Data System (ADS)

Theoretical mechanisms showing how antineutrons can enter a region of confined hydrogen or deuterium and decay into antiprotons is given. An annihilation reaction of a proton and antiproton releases energy. This starts a series of deuterium fissions that increase the probability of annihilation reactions. The gamma rays produced lose momentum via radiation pressure vibrations of the surrounding confinement lattice. This constitutes a change of radiation energy to kinetic energy, exhibited as heating of the lattice material. A likely mechanism of mass changing to energy is the annihilation of large particles breaking into a multiplicity of repeated less energetic positron annihilations. The explanation given shows that it is possible in theory to utilize the tremendous energy available from annihilation reactions. The harnessing of this final frontier of energy and power could ultimately prove to be the most useful energy source, particularly for propulsion systems. The reaction cited may be the initial step in using the energy from annihilation reactions. Excess heat from a Pons — Fleischmann-type reaction can be accounted for as annihilation, not fusion.

Jensen, L. Carl; Mortensen, Kay S.

1990-12-01

427

Charge-Confining Gravitational Electrovacuum Shock Wave  

NASA Astrophysics Data System (ADS)

In previous publications, we have extensively studied spherically symmetric solutions of gravity coupled to a nonstandard type of nonlinear electrodynamics containing a square-root of the ordinary Maxwell Lagrangian (the latter is known to yield quantum chromodynamic (QCD)-like confinement in a flat spacetime). A class of these solutions describe nonstandard black holes of Reissner-Nordström-(anti-)-de Sitter type with an additional constant radial vacuum electric field, in particular, a non-asymptotically flat Reissner-Nordström-type black hole. Here, we study the ultra-relativistic boost (Lousto-Sanchez extension of Aichelburg-Sexl) limit of the latter and show that, unlike the ordinary Reissner-Nordström case, we obtain a gravitational electrovacuum shock wave as a result of the persistence of the gauge field due to the "square-root" Maxwell Lagrangian term. Next, we show that this gravitational electrovacuum shock wave confines charged test particles (both massive and massless) within a finite distance from its front.

Guendelman, Eduardo; Nissimov, Emil; Pacheva, Svetlana

2014-01-01

428

Emergent phenomena in manganites under spatial confinement  

NASA Astrophysics Data System (ADS)

It is becoming increasingly clear that the exotic properties displayed by correlated electronic materials such as high-Tc superconductivity in cuprates, colossal magnetoresistance (CMR) in manganites, and heavy-fermion compounds are intimately related to the coexistence of competing nearly degenerate states which couple simultaneously active degrees of freedom—charge, lattice, orbital, and spin states. The striking phenomena associated with these materials are due in a large part to spatial electronic inhomogeneities, or electronic phase separation (EPS). In many of these hard materials, the functionality is a result of the soft electronic component that leads to self-organization. In this paper, we review our recent work on a novel spatial confinement technique that has led to some fascinating new discoveries about the role of EPS in manganites. Using lithographic techniques to confine manganite thin films to length scales of the EPS domains that reside within them, it is possible to simultaneously probe EPS domains with different electronic states. This method allows for a much more complete view of the phases residing in a material and gives vital information on phase formation, movement, and fluctuation. Pushing this trend to its limit, we propose to control the formation process of the EPS using external local fields, which include magnetic exchange field, strain field, and electric field. We term the ability to pattern EPS “electronic nanofabrication." This method allows us to control the global physical properties of the system at a very fundamental level, and greatly enhances the potential for realizing true oxide electronics.

Shen, Jian; Z. Ward, T.; F. Yin, L.

2013-01-01

429

Gain dans UN Plasma d'Aluminium Confine (Gain in a Confined Aluminum Plasma).  

National Technical Information Service (NTIS)

A confinement by a target with a form which retards the lateral expansion of a plasma is shown and discussed. The spatial distributions of the lithiumoid aluminum beam at 105.7 A and the neighboring beams are shown. These curves were obtained during a fiv...

P. Jaegle A. Carillon B. Gauthe G. Jamelot J. Raucourt

1990-01-01

430

Rythmes Biologiques, Sommeil et Vigilance en Confinement Prolonge (Biological Rhythms, Sleep, and Wakefulness in Prolonged Confinement).  

National Technical Information Service (NTIS)

The dysynchronization of human circadian rhythms during 7 long-term (2 to 6 months) confinement experiments in temporal isolation in caves was studied. Five subjects abandon the circadian period of sleep and wakefulness (S-W) and spontaneously reach a cir...

M. Siffre

1988-01-01

431

Hydrogen Confinement in Carbon Nanopores: Extreme Densification at Ambient Temperature  

SciTech Connect

In-situ small angle neutron scattering (SANS) studies of hydrogen confined in small pores of polyfurfuryl alcohol-derived activated carbon (PFAC) at room-temperature provided for the first time its phase behavior in equilibrium with external H2 at pressures up to 200 bar. The data was used to evaluate the density of the adsorbed fluid, which appears to be a function of both pore size and pressure, and approaches the liquid hydrogen density in narrow nanopores at 200 bar. The surface-molecule interactions responsible for densification of hydrogen within the pores create internal pressures which exceed by a factor of up to ~ 60 the external gas pressures, confirming the benefits of adsorptive over compressive storage. These results can be utilized to guide the development of new carbon adsorbents tailored for maximum hydrogen storage capacities at near ambient temperatures.

Gallego, Nidia C [ORNL; He, Lilin [ORNL; Saha, Dipendu [ORNL; Contescu, Cristian I [ORNL; Melnichenko, Yuri B [ORNL

2011-01-01

432

Investigation B: Laminar confined coaxial entrance flow with heat generation  

NASA Technical Reports Server (NTRS)

The results of a parametric study on the entrance flow region in a gas core nuclear reactor are presented. The physical system is modeled as laminar confined, coaxial flow with heat generation in the inner fluid. The governing equations include the boundary layer approximations and the assumptions of only radial radiative transport of energy represented as an energy diffusion term. The Von Mises transformation and a zeta transformation are used to transform the equations into nonlinear nonhomogeneous convective-diffusion equations. A unique combination of forward and backward difference equations which yields accurate results at moderate computational times, is used in the numerical method. Results show that the rapidly accelerating, heat generating inner stream actually shrinks in radius as it expands axially.

Bobba, G. K. M.; Weinstein, H.

1975-01-01

433

Development of Compton radiography of inertial confinement fusion implosions  

NASA Astrophysics Data System (ADS)

An important diagnostic tool for inertial confinement fusion will be time-resolved radiographic imaging of the dense cold fuel surrounding the hot spot. The measurement technique is based on point-projection radiography at photon energies from 60 to 200 keV where the Compton effect is the dominant contributor to the opacity of the fuel or pusher. We have successfully applied this novel Compton radiography technique to the study of the final compression of directly driven plastic capsules at the OMEGA facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. The radiographs have a spatial and temporal resolution of ~10 ?m and ~10 ps, respectively. A statistical accuracy of ~0.5% in transmission per resolution element is achieved, allowing localized measurements of areal mass densities to 7% accuracy. The experimental results show 3D nonuniformities and lower than 1D expected areal densities attributed to drive asymmetries and hydroinstabilities.

Tommasini, R.; Hatchett, S. P.; Hey, D. S.; Iglesias, C.; Izumi, N.; Koch, J. A.; Landen, O. L.; MacKinnon, A. J.; Sorce, C.; Delettrez, J. A.; Glebov, V. Yu.; Sangster, T. C.; Stoeckl, C.

2011-05-01

434

Development of Compton radiography of inertial confinement fusion implosions  

SciTech Connect

An important diagnostic tool for inertial confinement fusion will be time-resolved radiographic imaging of the dense cold fuel surrounding the hot spot. The measurement technique is based on point-projection radiography at photon energies from 60 to 200 keV where the Compton effect is the dominant contributor to the opacity of the fuel or pusher. We have successfully applied this novel Compton radiography technique to the study of the final compression of directly driven plastic capsules at the OMEGA facility [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)]. The radiographs have a spatial and temporal resolution of {approx}10 {mu}m and {approx}10 ps, respectively. A statistical accuracy of {approx}0.5% in transmission per resolution element is achieved, allowing localized measurements of areal mass densities to 7% accuracy. The experimental results show 3D nonuniformities and lower than 1D expected areal densities attributed to drive asymmetries and hydroinstabilities.

Tommasini, R.; Hatchett, S. P.; Hey, D. S.; Iglesias, C.; Izumi, N.; Koch, J. A.; Landen, O. L.; MacKinnon, A. J.; Sorce, C. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Delettrez, J. A.; Glebov, V. Yu.; Sangster, T. C.; Stoeckl, C. [Laboratory of Laser Energetics, Rochester, New York 14623-1299 (United States)

2011-05-15

435

Integrated diagnostic analysis of inertial confinement fusion capsule performance  

SciTech Connect

A conceptual model is developed for typical inertial confinement fusion implosion conditions that integrates available diagnostic information to determine the stagnation properties of the interior fill and surrounding shell. Assuming pressure equilibrium at peak compression and invoking radiative and equation-of-state relations, the pressure, density, and electron temperature are obtained by optimized fitting of the experimental output to smooth, global functional forms. Typical observational data that may be used includes x-ray self-emission, directional neutron time-of-flight signals, neutron yield, high-resolution x-ray spectra, and radiographic images. This approach has been validated by comparison with radiation-hydrodynamic simulations, producing semi-quantitative agreement. Model results implicate poor kinetic energy coupling to the hot core as the primary cause of the observed low thermonuclear burn yields.

Cerjan, Charles; Springer, Paul T.; Sepke, Scott M. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States)] [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States)

2013-05-15

436

Nonvolatile semiconductor memory having three dimension charge confinement  

DOEpatents

A layered semiconductor device with a nonvolatile three dimensional memory comprises a storage channel which stores charge carriers. Charge carriers flow laterally through the storage channel from a source to a drain. Isolation material, either a Schottky barrier or a heterojunction, located in a trench of an upper layer controllably retains the charge within the a storage portion determined by the confining means. The charge is retained for a time determined by the isolation materials' nonvolatile characteristics or until a change of voltage on the isolation material and the source and drain permit a read operation. Flow of charge through an underlying sense channel is affected by the presence of charge within the storage channel, thus the presences of charge in the memory can be easily detected.

Dawson, L. Ralph (Albuquerque, NM) [Albuquerque, NM; Osbourn, Gordon C. (Albuquerque, NM) [Albuquerque, NM; Peercy, Paul S. (Albuquerque, NM) [Albuquerque, NM; Weaver, Harry T. (Albuquerque, NM) [Albuquerque, NM; Zipperian, Thomas E. (Albuquerque, NM) [Albuquerque, NM

1991-01-01

437

Probing confined and unconfined hemoglobin molecules with photoacoustics  

NASA Astrophysics Data System (ADS)

Photoacoustic (PA) measurements on confined and unconfined hemoglobin molecules are presented. In vitro experiments were performed with porcine red blood cells (RBCs) at 532 and 1064 nm at various laser fluences. Fluence was gradually changed from 8 to 21 mJ/cm2/pulse for 532 nm and 353 to 643 mJ/cm2/pulse for 1064 nm. PA signals from suspended RBCs (SRBCs) and hemolyzed RBCs (HRBCs) were measured using a needle hydrophone at hematocrits ranging from 10 to 60%. PA amplitude was found to be varied linearly with the laser fluence for each type of samples at the above two optical radiations. At 532 nm, PA signals from SRBCs and HRBCs were measured to be nearly equal, whereas, at 1064 nm, signal amplitude for SRBCs was approximately 2 times higher than that of HRBCs. The results suggest that it may be feasible to detect hemolysis with PAs.

Saha, Ratan K.; Karmakar, Subhajit; Roy, Madhusudan

2014-03-01

438

Molecular Dynamics Study of Single Conjugated Polymers Confined to Nanoparticles  

NASA Astrophysics Data System (ADS)

Optically active polymers confined into nanoparticles are highly fluorescent and have potential applications in intracellular fluorescence imaging, bio-sensors and other optoelectronic devices. Internal conformation and dynamics of the polymers determines their optical properties. Using molecular dynamics (MD) simulations, we have explored the structure and dynamics of nanoparticles formed by conjugated polymers in a collapsed conformation, which is not the most stable conformation of the polymer. Nanoparticles were formed in a collapsed conformation and followed as the function of time in both poor and good solvents. We found that these nanoparticles are stable and remain collapsed in a poor solvent but rapidly expands and unraveled in a good solvent. The lengths of the side chains affect the internal packing of the side chains which in turn affect the size of the nanoparticles. S(q,t) was measured to characterize the internal dynamics of the collapsed nanoparticles.

Maskey, Sabina; Pierce, Flint; Perahia, Dvora; Grest, Gary

2011-03-01

439

Multiple-scale turbulence closure modeling of confined recirculating flows  

NASA Technical Reports Server (NTRS)

A multiple-scale turbulence closure scheme is developed for the numerical predictions of confined recirculating flows. This model is based on the multiple-time-scale concepts of Hanjalic et al. (1980) and takes into account the non-equilibrium spectra energy transfer mechanism. Problems concerning new formulation of energy transfer rate equations and subsequent model coefficient redefinition and energy spectrum partition are discussed. Comparisons are made with several experiments of internal recirculating flows for the purpose of model validation. Numerical results using the present model show significant improvement of predictive capability over that obtained with the single-scale k-epsilon model and show promising potential for complex turbulent flow predictions.

Chen, C. P.

1985-01-01

440

Perspectives on water science: transport and application of confined water  

NASA Astrophysics Data System (ADS)

The confinements of water can be divided into two main categories, namely, the confinements on surface or interface and the confinements in bulk water. By adding ions or applying electric field, the intensity and distribution of the hydrogen bonds can be greatly affected. These are collectively known as confinement on water surface or interface, which has potential applications in life science and industries involving evaporation control. Confined bulk water could be found everywhere in nature, such as in granular and porous materials, macromolecules and gels, etc. The investigation of the physical properties and the transports of the confined bulk water will contribute to understanding certain types of life activities such as the water transport in plant and in new application of extracting the shale oil and water.

Zeng, XiPing; Wu, JinBo; Li, ShunBo; Chau, YeungYeung; He, GuangHong; Wen, WeiJia; Yang, GuoZhen

2014-05-01

441

Perspectives on water science: transport and application of confined water  

NASA Astrophysics Data System (ADS)

The confinements of water can be divided into two main categories, namely, the confinements on surface or interface and the confinements in bulk water. By adding ions or applying electric field, the intensity and distribution of the hydrogen bonds can be greatly affected. These are collectively known as confinement on water surface or interface, which has potential applications in life science and industries involving evaporation control. Confined bulk water could be found everywhere in nature, such as in granular and porous materials, macromolecules and gels, etc. The investigation of the physical properties and the transports of the confined bulk water will contribute to understanding certain types of life activities such as the water transport in plant and in new application of extracting the shale oil and water.

Zeng, XiPing; Wu, JinBo; Li, ShunBo; Chau, YeungYeung; He, GuangHong; Wen, WeiJia; Yang, GuoZhen

2014-03-01

442

Quasi-symmetry in magnetic fusion energy confinement devices  

Microsoft Academic Search

Quasi-symmetry in three-dimensional magnetic confinement devices provides a path for external control of the confining magnetic field while achieving confinement comparable to axisymmetric configurations. In a quasi-symmetric toroidal configuration, magnetic field strength in magnetic flux coordinates depends primarily on two coordinates, B( ,) B( ,theta+ Nzeta) where M and N are integers. Here, psi is the flux coordinate (analogous to

Andrew Ware; Kathleen McGarvey

2010-01-01

443

Confinement and Tritium Stripping Systems for APT Tritium Processing  

SciTech Connect

This report identifies functions and requirements for the tritium process confinement and clean-up system (PCCS) and provides supporting technical information for the selection and design of tritium confinement, clean-up (stripping) and recovery technologies for new tritium processing facilities in the Accelerator for the Production of Tritium (APT). The results of a survey of tritium confinement and clean-up systems for large-scale tritium handling facilities and recommendations for the APT are also presented.

Hsu, R.H. [Westinghouse Savannah River Company, AIKEN, SC (United States); Heung, L.K.

1997-10-20

444

Simulation of Spheromak Evolution and Energy Confinement  

NASA Astrophysics Data System (ADS)

Electron temperatures near 400 eV were observed transiently in the Los Alamos CTX spheromak experiment.[1] Temperatures of 100-200 eV have been observed in the SSPX spheromak.[2] Understanding the energy confinement in these experiments is a challenging problem. Results from numerical simulations with the NIMROD nonlinear resistive MHD code (at zero or finite plasma pressure) have shown that closed flux surfaces with net current can arise only after electrostatic drive is reduced.[3,4] Computations in the last year have directly investigated the importance of inductive effects on energy confinement including the evolution of the temperature and number density using thermal transport coefficients, electrical resistivity, and Ohmic heating that are appropriate for collisional plasmas. In conditions with sustained coaxial electrostatic drive, the cold edge plasma impedes parallel thermal conduction to the wall, despite the chaotic magnetic topology, allowing the plasma core temperature to reach tens of eVs. When the drive is temporarily removed, relatively symmetric closed flux surfaces form. Magnetic reconnection occurs rapidly in the cold outer plasma, and core temperatures increase toward 100 eV or more. Applying a second current pulse, as in some SSPX discharges,[5] is shown to improve performance by delaying the onset of MHD modes that are resonant in the closed-flux region, and higher current, increased magnetic fields, and larger volumes of closed flux can be achieved. The simulations reveal the sensitivity with respect to symmetry-breaking magnetic fluctuations of the magnetic surfaces and the energy confinement. We present a detailed comparison of results from nonlinear simulations with laboratory measurements from SSPX[5,6] and assess transport mechanisms through computational diagnostics. The simulation results are yielding electron temperatures and other features agreeing well with SSPX observations. [1] T. R. Jarboe, Plasma Phys. Control. Fusion 36, 945 (1994). [2] H. S. McLean, et al., Phys. Rev. Lett. 88, 125004 (2002); H.S. McLean, S. Woodruff, D.N. Hill, et al., 30th EPS Conference on Controlled Fusion and Plasma Physics, Saint Petersburg, Russia, July 7-11 2003. Europhysics conference abstracts, 27A, p3/230. http://epsppd.epfl.ch/StPetersburg/PDF/P3-230. [3] C. R. Sovinec, J. M. Finn, D. del-Castillo-Negrete, Phys. Plasmas 8, 475 (2001). [4] R.H. Cohen, H.L. Berk, B.I. Cohen, et al., Nucl. Fusion 43, 1220 (2003). [5] S. Woodruff, et al., submitted to Phys. Rev. Lett. [6] S. Woodruff, D. N. Hill, et al., Phys. Rev. Lett. 90, 95001(2003).

Cohen, Bruce I.

2004-11-01

445

Dynamics of viral hemorrhagic septicemia, viral erythrocytic necrosis and ichthyophoniasis in confined juvenile Pacific herring Clupea pallasii  

USGS Publications Warehouse

Capture of wild, juvenile herring Clupea pallasii from Puget Sound (Washington, USA) and confinement in laboratory tanks resulted in outbreaks of viral hemorrhagic septicemia (VHS), viral erythrocytic necrosis (VEN) and ichthyophoniasis; however, the timing and progression of the 3 diseases differed. The VHS epidemic occurred first, characterized by an initially low infection prevalence that increased quickly with confinement time, peaking at 93 to 98% after confinement for 6 d, then decreasing to negligible levels after 20 d. The VHS outbreak was followed by a VEN epidemic that, within 12 d of confinement, progressed from undetectable levels to 100% infection prevalence with >90% of erythrocytes demonstrating inclusions. The VEN epidemic persisted for 54 d, after which the study was terminated, and was characterized by severe blood dyscrasias including reduction of mean hematocrit from 42 to 6% and replacement of mature erythrocytes with circulating erythroblasts and ghost cells. All fish with ichthyophoniasis at capture died within the first 3 wk of confinement, probably as a result of the multiple stressors associated with capture, transport, confinement, and progression of concomitant viral diseases. The results illustrate the differences in disease ecology and possible synergistic effects of pathogens affecting marine fish and highlight the difficulty in ascribing a single causation to outbreaks of disease among populations of wild fishes. ?? Inter-Research 2006.

Hershberger, P.; Hart, A.; Gregg, J.; Elder, N.; Winton, J.

2006-01-01

446

Aging and stiction dynamics in confined films of a star polymer melt  

NASA Astrophysics Data System (ADS)

The stiction properties of a star polyisoprene (PIP) melt (having 22 arms and an arm molecular weight of around 5000, Mw ~ 110 000) confined between mica surfaces were investigated using the surface forces apparatus. Stop-start experiments were carried out and the stiction spike was measured as a function of surface stopping (aging) time t and applied pressure P; the time constants of the phase transitions in the stiction dynamics (freezing on stopping and melting on starting) were obtained from the force relaxation behaviors. The results were compared with those of a confined linear-PIP melt (Mw ~ 48 000) and other confined fluid systems; the effect of star architecture on the phase transitions in confinement during aging is discussed. Estimation of the molecular size gives that the confined star-PIP films consist of three molecular layers; a non-adsorbed layer sandwiched between two layers adsorbed on opposed mica surfaces. There are (at least) four time constants in the freezing transition of the confined star-PIP melt; fast (?1) and slow (?2) time constants for lateral force relaxation on stopping, critical aging time for freezing (?f), and the logarithmic increase of the spike height against t. The three time constants on stopping, ?1, ?2, and ?f, increase with the increase of P (decrease of the thickness D). As regards the melting transition on starting, spike force decay was fitted by a single exponential function and one time constant was obtained, which is insensitive to P (D). Comparison of the time constants between freezing and melting, and also with the results of linear-PIP reveals that the stiction dynamics of the star-PIP system involves the relaxation and rearrangement of segmental-level and whole molecular motions. Lateral force relaxation on stopping is governed by the individual and cooperative rearrangements of local PIP segments and chain ends of the star, which do not directly lead to the freezing of the system. Instead, geometrical rearrangements of the soft star-PIP spheres into dense packing between surfaces (analogous to the concept of a colloidal glass transition) are the major mechanism of the freezing transition (stiction) after aging. Interdigitation of PIP segments/chain ends between neighboring star molecules also contributes to the spike growth along with aging, and the melting transition on starting.

Yamada, Shinji

2012-11-01

447

Particle-in-Cell Simulation of Inertial Electrostatic Confinement Fusion Plasma  

Microsoft Academic Search

A particle-in-cell calculation code was made to simulate the operation of an inertial electrostatic confinement (IEC) fusion device. The computation includes the effects of ionization by electron impact. Several techniques to save computational time are introduced in this program code. One of them is time-dependent fine space meshes used in the regions where the particles concentrate. Several superparticles that have

Masami Ohnishi; Hodaka Osawa; Kiyoshi Yoshikawa; Kai Masuda; Yasushi Yamamoto

2001-01-01

448

The cruel and unusual phenomenology of solitary confinement  

PubMed Central

What happens when subjects are deprived of intersubjective contact? This paper looks closely at the phenomenology and psychology of one example of that deprivation: solitary confinement. It also puts the phenomenology and psychology of solitary confinement to use in the legal context. Not only is there no consensus on whether solitary confinement is a “cruel and unusual punishment,” there is no consensus on the definition of the term “cruel” in the use of that legal phrase. I argue that we can find a moral consensus on the meaning of “cruelty” by looking specifically at the phenomenology and psychology of solitary confinement.

Gallagher, Shaun

2014-01-01

449

The cruel and unusual phenomenology of solitary confinement.  

PubMed

What happens when subjects are deprived of intersubjective contact? This paper looks closely at the phenomenology and psychology of one example of that deprivation: solitary confinement. It also puts the phenomenology and psychology of solitary confinement to use in the legal context. Not only is there no consensus on whether solitary confinement is a "cruel and unusual punishment," there is no consensus on the definition of the term "cruel" in the use of that legal phrase. I argue that we can find a moral consensus on the meaning of "cruelty" by looking specifically at the phenomenology and psychology of solitary confinement. PMID:24971072

Gallagher, Shaun

2014-01-01

450

Confinement dynamics of a semiflexible chain inside nano-spheres  

NASA Astrophysics Data System (ADS)

We study the conformations of a semiflexible chain, confined in nano-scaled spherical cavities, under two distinct processes of confinement. Radial contraction and packaging are employed as two confining procedures. The former method is performed by gradually decreasing the diameter of a spherical shell which envelopes a confined chain. The latter procedure is carried out by injecting the chain inside a spherical shell through a hole on the shell surface. The chain is modeled with a rigid body molecular dynamics simulation and its parameters are adjusted to DNA base-pair elasticity. Directional order parameter is employed to analyze and compare the confined chain and the conformations of the chain for two different sizes of the spheres are studied in both procedures. It is shown that for the confined chains in the sphere sizes of our study, they appear in spiral or tennis-ball structures, and the tennis-ball structure is more likely to be observed in more compact confinements. Our results also show that the dynamical procedure of confinement and the rate of the confinement are influential parameters of the structure of the chain inside spherical cavities.

Fathizadeh, A.; Heidari, Maziar; Eslami-Mossallam, B.; Ejtehadi, M. R.