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Sample records for rotation viscosity pinch

  1. Rotating plasma disks in dense Z-pinch experiments

    SciTech Connect

    Bennett, M. J. E-mail: s.lebedev@imperial.ac.uk; Lebedev, S. V. E-mail: s.lebedev@imperial.ac.uk; Suttle, L.; Burdiak, G.; Suzuki-Vidal, F.; Hare, J.; Swadling, G.; Patankar, S.; Bocchi, M.; Chittenden, J. P.; Smith, R.; Hall, G. N.; Frank, A.; Blackman, E.; Drake, R. P.; Ciardi, A.

    2014-12-15

    We present data from the first z-pinch experiments aiming to simulate aspects of accretion disk physics in the laboratory. Using off axis ablation flows from a wire array z-pinch we demonstrate the formation of a hollow disk structure that rotates at 60 kms{sup −1} for 150 ns. By analysing the Thomson scattered spectrum we make estimates for the ion and electron temperatures as T{sub i} ∼ 60 eV and ZT{sub e} ∼ 150 to 200 eV.

  2. Shape of pinch and swell structures as a viscosity indicator: Application to lower crustal polyphase rocks

    NASA Astrophysics Data System (ADS)

    Gardner, Robyn L.; Piazolo, Sandra; Daczko, Nathan R.

    2016-07-01

    Pinch and swell structures occur where a more competent layer in a weaker matrix is subjected to layer-parallel extension. In this contribution, we use numerical models to explore the use of pinch and swell structure shape symmetry and asymmetry as a determinant of relative viscosity between layers. Maximum asymmetry is attained when the matrix viscosity on one side is subtly weaker than the competent layer, while the other side is significantly weaker. Our numerical results are directly applied to asymmetrically developed pinch and swell structures in exposed lower continental crust. Here, shape geometries observed in a shear zone comprised of plagioclase-dominated, garnet-dominated and mixed amphibole-plagioclase-dominated bands, reveals that the plagioclase-dominated band is the most competent band and is marginally stronger (2×) and significantly stronger (10-40×) than the fine grained garnet-dominated and mixed amphibole-plagioclase-dominated band, respectively. Based on the experimentally determined viscosity of a plagioclase-dominated material and quantitative microstructural analysis, the viscosity range of the natural rock bands is 2.8 × 1015 to 1.1 × 1017 Pa s. Consequently, the assumption that the experimentally-derived plagioclase flow law is an appropriate proxy for the middle to lower continental crust may lead to a viscosity over-estimation by up to forty times.

  3. Mixing of a passive scalar by the instability of a differentially rotating axial pinch

    NASA Astrophysics Data System (ADS)

    Paredes, A.; Gellert, M.; Rüdiger, G.

    2016-04-01

    The mean-field diffusion of passive scalars such as lithium, beryllium or temperature dispersals due to the magnetic Tayler instability of a rotating axial pinch is considered. Our study is carried out within a Taylor-Couette setup for two rotation laws: solid-body quasi-Kepler rotation. The minimum magnetic Prandtl number used is 0.05, and the molecular Schmidt number Sc of the fluid varies between 0.1 and 2. An effective diffusivity coefficient for the mixing is numerically measured by the decay of a prescribed concentration peak located between both cylinder walls. We find that only models with Sc exceeding 0.1 basically provide finite instability-induced diffusivity values. We also find that for quasi-Kepler rotation at a magnetic Mach number Mm ≃ 2, the flow transits from the slow-rotation regime to the fast-rotation regime that is dominated by the Taylor-Proudman theorem. For fixed Reynolds number, the relation between the normalized turbulent diffusivity and the Schmidt number of the fluid is always linear so that also a linear relation between the instability-induced diffusivity and the molecular viscosity results, just in the sense proposed by Schatzman (1977, A&A, 573, 80). The numerical value of the coefficient in this relation reaches a maximum at Mm ≃ 2 and decreases for larger Mm, implying that only toroidal magnetic fields on the order of 1 kG can exist in the solar tachocline.

  4. Sheared E×B flow and plasma turbulence viscosity in a Reversed Field Pinch

    NASA Astrophysics Data System (ADS)

    Vianello, N.; Antoni, V.; Spada, E.; Spolaore, M.; Serianni, G.; Regnoli, G.; Zuin, M.; Cavazzana, R.; Bergsåker, H.; Cecconello, M.; Drake, J. R.

    2004-11-01

    The relationship between electromagnetic turbulence and sheared plasma flow in Reversed Field Pinch configuration is addressed. The momentum balance equation for a compressible plasma is considered and the terms involved are measured in the outer region of Extrap-T2R RFP device. It results that electrostatic fluctuations determine the plasma flow through the electrostatic component of Reynolds Stress tensor. This term involves spatial and temporal scales comparable to those of MHD activity. The derived experimental perpendicular viscosity is consistent with anomalous diffusion, the latter being discussed in terms of electrostatic turbulence background and coherent structures emerging from fluctuations. The results indicate a dynamical interplay between turbulence, anomalous transport and mean E×B profiles. The momentum balance has been studied also in non-stationary condition during the application of Pulsed Poloidal Current Drive, which is known to reduce the amplitude of MHD modes.

  5. Investigating plasma viscosity with fast framing photography in the ZaP-HD Flow Z-Pinch experiment

    NASA Astrophysics Data System (ADS)

    Weed, Jonathan Robert

    The ZaP-HD Flow Z-Pinch experiment investigates the stabilizing effect of sheared axial flows while scaling toward a high-energy-density laboratory plasma (HEDLP > 100 GPa). Stabilizing flows may persist until viscous forces dissipate a sheared flow profile. Plasma viscosity is investigated by measuring scale lengths in turbulence intentionally introduced in the plasma flow. A boron nitride turbulence-tripping probe excites small scale length turbulence in the plasma, and fast framing optical cameras are used to study time-evolved turbulent structures and viscous dissipation. A Hadland Imacon 790 fast framing camera is modified for digital image capture, but features insufficient resolution to study turbulent structures. A Shimadzu HPV-X camera captures the evolution of turbulent structures with great spatial and temporal resolution, but is unable to resolve the anticipated Kolmogorov scale in ZaP-HD as predicted by a simplified pinch model.

  6. Bulk viscosity of accretion disks around non rotating black holes

    NASA Astrophysics Data System (ADS)

    Moeen Moghaddas, M.

    2017-01-01

    In this paper, we study the Keplerian, relativistic accretion disks around the non rotating black holes with the bulk viscosity. Many of authors studied the relativistic accretion disks around the black holes, but they ignored the bulk viscosity. We introduce a simple method to calculate the bulk in these disks. We use the simple form for the radial component of the four velocity in the Schwarzschild metric, then the other components of the four velocity and the components of the shear and the bulk tensor are calculated. Also all components of the bulk viscosity, the shear viscosity and stress tensor are calculated. It is seen that some components of the bulk tensor are comparable with the shear tensor. We calculate some of the thermodynamic quantities of the relativistic disks. Comparison of thermodynamic quantities shows that in some states influences of the bulk viscosity are important, especially in the inner radiuses. All calculations are done analytically and we do not use the boundary conditions. Finally, we find that in the relativistic disks around the black holes, the bulk viscosity is non-negligible in all the states.

  7. Ferrohydrodynamic evaluation of rotational viscosity and relaxation in certain ferrofluids.

    PubMed

    Patel, Rajesh

    2012-07-01

    A significant effect of aggregation dynamics for aqueous ferrofluid (AF) and kerosene based ferrofluid (KF) using magnetic field dependent capillary viscosity and magneto-optical relaxation measurements is studied. For better comparison parameters of AF and KF are kept similar. Ferrohydrodynamic equations of chain forming ferrofluids, dilute ferrofluids, and Brownian dynamic simulations are compared. It is observed that the rotational viscosity of AF is larger than that of KF due to field induced aggregates in it and strong dipolar interactions. It is also observed that at Ωτ ~ 0.04 both AF and KF viscosity becomes almost similar, suggesting similar behavior at that shear rate. The magneto-optical relaxation in AF exhibits nonexponential behavior when relaxed from higher magnetic field and follows irreversible thermodynamics, whereas for KF the relaxation is exponential and follows the effective field method. This discrepancy is explained based on aggregation dynamics of magnetic particles. Results are well described by the corresponding theoretical models.

  8. Effect of temperature on rotational viscosity in magnetic nano fluids.

    PubMed

    Patel, R

    2012-10-01

    Flow behavior of magnetic nano fluids with simultaneous effect of magnetic field and temperature is important for its application for cooling devices such as transformer, loud speakers, electronic cooling and for its efficiency in targeted drug delivery and hyperthermia treatment. Using a specially designed horizontal capillary viscometer, temperature-sensitive and non-temperature-sensitive magnetic nano fluids are studied. In both these case the temperature-dependent rotational viscosity decreases, but follows a quite different mechanism. For temperature-sensitive magnetic nano fluids, the reduction in rotational viscosity is due to the temperature dependence of magnetization. Curie temperature ((T)(c)) and pyromagnetic coefficient are extracted from the study. A fluid with low T(c) and high pyromagnetic coefficient is useful for thermo-sensitive cooling devices and magnetic hyperthermia. For non-temperature-sensitive magnetic nano fluids, reduction in rotational viscosity is due to removal of physisorbed secondary surfactant on the particle because of thermal and frictional effects. This can be a good analogy for removal of drug from the magnetic particles in the case of targeted drug delivery.

  9. Measuring Lipid Membrane Viscosity Using Rotational and Translational Probe Diffusion

    NASA Astrophysics Data System (ADS)

    Hormel, Tristan T.; Kurihara, Sarah Q.; Brennan, M. Kathleen; Wozniak, Matthew C.; Parthasarathy, Raghuveer

    2014-05-01

    The two-dimensional fluidity of lipid bilayers enables the motion of membrane-bound macromolecules and is therefore crucial to biological function. Microrheological methods that measure fluid viscosity via the translational diffusion of tracer particles are challenging to apply and interpret for membranes, due to uncertainty about the local environment of the tracers. Here, we demonstrate a new technique in which determination of both the rotational and translational diffusion coefficients of membrane-linked particles enables quantification of viscosity, measurement of the effective radii of the tracers, and assessment of theoretical models of membrane hydrodynamics. Surprisingly, we find a wide distribution of effective tracer radii, presumably due to a variable number of lipids linked to each tracer particle. Furthermore, we show for the first time that a protein involved in generating membrane curvature, the vesicle trafficking protein Sar1p, dramatically increases membrane viscosity. Using the rheological method presented here, therefore, we are able to reveal a class of previously unknown couplings between protein activity and membrane mechanics.

  10. Spontaneous generation of a sheared plasma rotation in a field-reversed θ-pinch discharge.

    PubMed

    Omelchenko, Y A; Karimabadi, H

    2012-08-10

    By conducting two-dimensional hybrid simulations of an infinitely long field-reversed θ-pinch discharge we discover a new type of plasma rotation, which rapidly develops at the plasma edge in the ion diamagnetic direction due to the self-consistent generation of a Hall-driven radial electric field. This effect is different from the previously identified end-shorting and particle-loss mechanisms. We also demonstrate flutelike perturbations frequently inferred in experiments and show that in the absence of axial contraction effects they may quickly alter the toroidal symmetry of the plasma.

  11. Time variability of viscosity parameter in differentially rotating discs

    NASA Astrophysics Data System (ADS)

    Rajesh, S. R.; Singh, Nishant K.

    2014-07-01

    We propose a mechanism to produce fluctuations in the viscosity parameter (α) in differentially rotating discs. We carried out a nonlinear analysis of a general accretion flow, where any perturbation on the background α was treated as a passive/slave variable in the sense of dynamical system theory. We demonstrate a complete physical picture of growth, saturation and final degradation of the perturbation as a result of the nonlinear nature of coupled system of equations. The strong dependence of this fluctuation on the radial location in the accretion disc and the base angular momentum distribution is demonstrated. The growth of fluctuations is shown to have a time scale comparable to the radial drift time and hence the physical significance is discussed. The fluctuation is found to be a power law in time in the growing phase and we briefly discuss its statistical significance.

  12. Mode- and plasma rotation in a resistive shell reversed-field pinch

    NASA Astrophysics Data System (ADS)

    Malmberg, J.-A.; Brzozowski, J.; Brunsell, P. R.; Cecconello, M.; Drake, J. R.

    2004-02-01

    Mode rotation studies in a resistive shell reversed-field pinch, EXTRAP T2R [P. R. Brunsell et al., Plasma Phys. Control. Fusion 43, 1 (2001)] are presented. The phase relations and nonlinear coupling of the resonant modes are characterized and compared with that expected from modeling based on the hypothesis that mode dynamics can be described by a quasi stationary force balance including electromagnetic and viscous forces. Both m=0 and m=1 resonant modes are studied. The m=1 modes have rotation velocities corresponding to the plasma flow velocity (20-60 km/s) in the core region. The rotation velocity decreases towards the end of the discharge, although the plasma flow velocity does not decrease. A rotating phase locked m=1 structure is observed with a velocity of about 60 km/s. The m=0 modes accelerate throughout the discharges and reach velocities as high as 150-250 km/s. The observed m=0 phase locking is consistent with theory for certain conditions, but there are several conditions when the dynamics are not described. This is not unexpected because the assumption of quasi stationarity for the mode spectra is not fulfilled for many conditions. Localized m=0 perturbations are formed in correlation with highly transient discrete dynamo events. These perturbations form at the location of the m=1 phase locked structure, but rotate with a different velocity as they spread out in the toroidal direction.

  13. NUMERICAL SIMULATIONS OF Z-PINCH EXPERIMENTS TO CREATE SUPERSONIC DIFFERENTIALLY ROTATING PLASMA FLOWS

    SciTech Connect

    Bocchi, M.; Ummels, B.; Chittenden, J. P.; Lebedev, S. V.; Frank, A.; Blackman, E. G.

    2013-04-10

    The physics of accretion disks is of fundamental importance for understanding of a wide variety of astrophysical sources that includes protostars, X-ray binaries, and active galactic nuclei. The interplay between hydrodynamic flows and magnetic fields and the potential for turbulence-producing instabilities is a topic of active research that would benefit from the support of dedicated experimental studies. Such efforts are in their infancy, but in an effort to push the enterprise forward we propose an experimental configuration which employs a modified cylindrical wire array Z-pinch to produce a rotating plasma flow relevant to accretion disks. We present three-dimensional resistive magnetohydrodynamic simulations which show how this approach can be implemented. In the simulations, a rotating plasma cylinder or ring is formed, with typical rotation velocity {approx}30 km s{sup -1}, Mach number {approx}4, and Reynolds number in excess of 10{sup 7}. The plasma is also differentially rotating. Implementation of different external magnetic field configurations is discussed. It is found that a modest uniform vertical field of 1 T can affect the dynamics of the system and could be used to study magnetic field entrainment and amplification through differential rotation. A dipolar field potentially relevant to the study of accretion columns is also considered.

  14. Rotation in a reversed field pinch with active feedback stabilization of resistive wall modes

    NASA Astrophysics Data System (ADS)

    Cecconello, M.; Menmuir, S.; Brunsell, P. R.; Kuldkepp, M.

    2006-09-01

    Active feedback stabilization of multiple resistive wall modes (RWMs) has been successfully proven in the EXTRAP T2R reversed field pinch. One of the features of plasma discharges operated with active feedback stabilization, in addition to the prolongation of the plasma discharge, is the sustainment of the plasma rotation. Sustained rotation is observed both for the internally resonant tearing modes (TMs) and the intrinsic impurity oxygen ions. Good quantitative agreement between the toroidal rotation velocities of both is found: the toroidal rotation is characterized by an acceleration phase followed, after one wall time, by a deceleration phase that is slower than in standard discharges. The TMs and the impurity ions rotate in the same poloidal direction with also similar velocities. Poloidal and toroidal velocities have comparable amplitudes and a simple model of their radial profile reproduces the main features of the helical angular phase velocity. RWMs feedback does not qualitatively change the TMs behaviour and typical phenomena such as the dynamo and the 'slinky' are still observed. The improved sustainment of the plasma and TMs rotation occurs also when feedback only acts on internally non-resonant RWMs. This may be due to an indirect positive effect, through non-linear coupling between TMs and RWMs, of feedback on the TMs or to a reduced plasma-wall interaction affecting the plasma flow rotation. Electromagnetic torque calculations show that with active feedback stabilization the TMs amplitude remains well below the locking threshold condition for a thick shell. Finally, it is suggested that active feedback stabilization of RWMs and current profile control techniques can be employed simultaneously thus improving both the plasma duration and its confinement properties.

  15. Field induced rotational viscosity of ferrofluid: effect of capillary size and magnetic field direction.

    PubMed

    Andhariya, Nidhi; Chudasama, Bhupendra; Patel, Rajesh; Upadhyay, R V; Mehta, R V

    2008-07-01

    In the present investigation we report the effect of capillary diameter and the direction of applied magnetic field on the rotational viscosity of water and kerosene based ferrofluids. We found that changes in the field induced rotational viscosity are larger in the case of water based magnetic fluid than that of kerosene based fluid. The field induced rotational viscosity is found to be inversely proportional to the capillary diameter and it falls exponentially as a function of the angle between the direction of field and vorticity of flow. Magnetophoretic mobility and hydrodynamic volume fraction of nanomagnetic particles are determined for above cases.

  16. Novel Rotating Hairy Black Hole in (2+1)-Dimensions and Shear Viscosity to Entropy Ratio

    NASA Astrophysics Data System (ADS)

    Naji, J.; Heshmatian, S.

    2014-08-01

    The novel rotating hairy black hole metric in (2 + 1) dimensions, which is an exact solution to the field equations of the Einstein-scalar AdS theory with a non-minimal coupling, considered in this paper and some hydrodynamics quantities such as diffusion constant and shear viscosity investigated. By using thermodynamics quantities such as temperature and entropy we can use diffusion constant to obtain shear viscosity and then calculate shear viscosity to entropy ratio.

  17. Evaluation of Lama glama semen viscosity with a cone-plate rotational viscometer.

    PubMed

    Casaretto, C; Martínez Sarrasague, M; Giuliano, S; Rubin de Celis, E; Gambarotta, M; Carretero, I; Miragaya, M

    2012-05-01

    Llama semen is highly viscous. This characteristic is usually evaluated subjectively by measuring the thread formed when carefully pippeting a sample of semen. The aims of this study were (i) to objectively determine and analyse llama semen viscosity, (ii) to compare semen viscosity between ejaculates of the same male as well as between different males, (iii) to study the correlation between viscosity and other semen characteristics and (iv) to evaluate the effect of collagenase on semen viscosity. Semen viscosity was evaluated using a cone-plate Brookfield rotational viscometer. A non Newtonian, pseudoplastic behaviour was observed in the 45 semen samples evaluated. Rheological parameters were determined obtaining the following results (mean ± SD): apparent viscosity at 11.5 s(-1): 46.71 ± 26.8 cpoise and at 115 s(-1): 12.61 ± 4.1 cpoise; structural viscosity (K) (dyne s cm(-2)): 2.18 ± 1.4 and coefficient of consistency (n): 0.45 ± 0.1. Statistical differences were found between different ejaculates of the same male for structural viscosity and apparent viscosity at 11.5 s(-1) (P < 0.01). Correlation was found only between coefficient of consistency (n) and sperm concentration (P < 0.01). Significant differences for coefficient of consistency (n) and viscosity at 115 s(-1) were found between samples incubated with and without collagenase (P < 0.05).

  18. Jeans instability of rotating anisotropic plasma with tensor viscosity

    NASA Astrophysics Data System (ADS)

    Patidar, Archana; Sharma, Prerana

    2017-05-01

    In the present work, the role of rotation with viscous tensor in anisotropic self-gravitating plasma has been investigated using magnetohydrodynamic (MHD) model and Chew-Goldberger-Low (CGL) fluid theory. The general dispersion relation is obtained by normal mode analysis theory with the help of linearized perturbation equations and further discussed with some limiting cases. The modified condition for Jeans instability has been obtained. The influence of considered parameters on the growth rate of instability is shown analytically and numerically. The result of present study may be useful in the region of spiral arms of galaxy.

  19. Error field assessment from driven rotation of stable external kinks at EXTRAP-T2R reversed field pinch

    NASA Astrophysics Data System (ADS)

    Volpe, F. A.; Frassinetti, L.; Brunsell, P. R.; Drake, J. R.; Olofsson, K. E. J.

    2013-04-01

    A new non-disruptive error field (EF) assessment technique not restricted to low density and thus low beta was demonstrated at the EXTRAP-T2R reversed field pinch. Stable and marginally stable external kink modes of toroidal mode number n = 10 and n = 8, respectively, were generated, and their rotation sustained, by means of rotating magnetic perturbations of the same n. Due to finite EFs, and in spite of the applied perturbations rotating uniformly and having constant amplitude, the kink modes were observed to rotate non-uniformly and be modulated in amplitude. This behaviour was used to precisely infer the amplitude and approximately estimate the toroidal phase of the EF. A subsequent scan permitted to optimize the toroidal phase. The technique was tested against deliberately applied as well as intrinsic EFs of n = 8 and 10. Corrections equal and opposite to the estimated error fields were applied. The efficacy of the error compensation was indicated by the increased discharge duration and more uniform mode rotation in response to a uniformly rotating perturbation. The results are in good agreement with theory, and the extension to lower n, to tearing modes and to tokamaks, including ITER, is discussed.

  20. Time dependent parallel viscosity and relaxation rate of poloidal rotation in the banana regime

    SciTech Connect

    Hsu, C.T.; Shaing, K.C.; Gormley, R. )

    1994-01-01

    Time dependent ion parallel viscous force in the banana regime with arbitrary inverse aspect ratio [epsilon] is calculated using the eigenfunction approach. The flux surface averaged viscosity is then used to study the relaxation process of the poloidal rotation which leads to oscillatory relaxation behavior. The relaxation rate [nu][sub [ital p

  1. Resonance parallel viscosity in the banana regime in poloidally rotating tokamak plasmas

    SciTech Connect

    Shaing, K.C.; Hsu, C.T.; Dominguez, N. )

    1994-05-01

    Parallel viscosity in the banana regime in a poloidally ([bold E][times][bold B]) rotating tokamak plasma is calculated to include the effects of orbit squeezing and to allow the poloidal [bold E][times][bold B] Mach number [ital M][sub [ital p

  2. GIA-related rotational variations for the Earth with low-viscosity D″ layer

    NASA Astrophysics Data System (ADS)

    Nakada, Masao; Okuno, Jun'ichi

    2013-11-01

    We examine the rotational variations due to the glacial isostatic adjustment (GIA) process for the Earth with a low-viscosity D″ layer of 300 km thickness. The rate of change of degree-two harmonics of the Earth's geopotential, {dot J}_2, proportional to rate of change of the rotation, is not so sensitive to the D″ layer with viscosities smaller than 1020 Pa s, but the polar wander rate is significantly sensitive to its low viscosity. The difference is attributed to the physics of Liouville equation describing the rotational variations in the postglacial phase. The {dot J}_2 only depends on viscous relaxation of inertia elements for the surface mass redistribution in the glacial and deglacial phases (convolution for load Love number), referred to as `load term' here. On the other hand, the polar wander rate depends on the load term and also rotational potential perturbations for changing polar motion (convolution for tidal Love number), referred to as `tidal term' here. It is crucially important to note that the tidal term is excited even in the postglacial phase until the relaxation completes. These two terms respond to the GIA process by different sensitivities to the lower-mantle viscosity above the D″ layer (ηlm) and the viscosity of the D″ layer (ηD″). In fact, the ηlm-sensitivity of the polar wander rate is significantly different in the load and tidal terms, and that for the load term is identical to that for the {dot J}_2 as expected. Although the ηlm-sensitivity of the tidal term is essentially independent of the low viscosity of D″ layer, there is a significant difference in degree of ηlm-sensitivity in adopted viscosity models with no low-viscosity D″ layer and with low-viscosity D″ layer of (1-10) × 1018 Pa s. The difference is attributed to the ηD″-sensitivities of two fundamental relaxation modes due to the density jumps at the surface and the core-mantle boundary.

  3. Rotation roots and neoclassical viscosity in quasi-symmetry

    NASA Astrophysics Data System (ADS)

    Cole, A. J.; Hegna, C. C.; Callen, J. D.

    2009-11-01

    In a quasi-symmetric device, there exists a symmetry angle αh= θ-Nζ/M, such that |B| = B0(1 - ɛhM αh ) along a field-line, with several much smaller helical `sidebands.' Provided the departure from symmetry is small, i.e. δBeff/B0ɛh where δBeff/B0 is the effective helical sideband strength, flow damping and thus flow evolution along and `cross' the direction of symmetry in a flux surface decouple [1,2], and can be determined successively. In the context of a fluid-moment approach [3], the momentum equation in the symmetry direction is equivalent to the ambipolarity condition. Steady state rotation solutions of this equation are equivalent to ambipolar radial electric field `roots' in conventional stellarator theory and will be presented for various banana-drift neoclassical flow damping regimes [2].[4pt] [1] J. D. Callen, A. J. Cole, and C. C. Hegna, Tech. Rep. UW-CPTC 08-7, Univ. of Wisconsin, http://www.cptc.wisc.edu (2009).[0pt] [2] A. J. Cole, C. C. Hegna, and J. D. Callen, Tech. Rep. UW-CPTC 08-8, Univ. of Wisconsin, http://www.cptc.wisc.edu (2009).[0pt] [3] K. C. Shaing and J. D. Callen, Phys. Fluids 26, 3315 (1983).

  4. Compact Pinch Welder

    NASA Technical Reports Server (NTRS)

    Starck, Thomas F.; Brennan, Andrew D.

    1990-01-01

    Compact resistance-welding pinch gun lets one operator do jobs formerly needing two workers. Light in weight and produces repeatable, high-quality weld joints. Welding-electrode head rotates for easy positioning. Lever at top of handle activates spring to pinch electrodes together at preset welding force. Button at bottom of handle activates welding current. Cables supply electrical power.

  5. Probing viscosity of nanoliter droplets of butterfly saliva by magnetic rotational spectroscopy

    NASA Astrophysics Data System (ADS)

    Tokarev, Alexander; Kaufman, Bethany; Gu, Yu; Andrukh, Taras; Adler, Peter H.; Kornev, Konstantin G.

    2013-01-01

    Magnetic rotational spectroscopy was employed for rheological analysis of nanoliter droplets of butterfly saliva. Saliva viscosity of butterflies is 4-5 times greater than that of water and similar to that of 30%-40% sucrose solutions at 25 °C. Hence, viscosity stratification would not be expected when butterflies feed on nectar with 30%-40% sugar concentrations. We did not observe any viscoelastic effects or non-Newtonian behavior of saliva droplets. Thus, butterfly saliva is significantly different rheologically from that of humans, which demonstrates a viscoelastic behavior.

  6. Variable Viscosity Effects on Time Dependent Magnetic Nanofluid Flow past a Stretchable Rotating Plate

    NASA Astrophysics Data System (ADS)

    Ram, Paras; Joshi, Vimal Kumar; Sharma, Kushal; Walia, Mittu; Yadav, Nisha

    2016-01-01

    An attempt has been made to describe the effects of geothermal viscosity with viscous dissipation on the three dimensional time dependent boundary layer flow of magnetic nanofluids due to a stretchable rotating plate in the presence of a porous medium. The modelled governing time dependent equations are transformed a from boundary value problem to an initial value problem, and thereafter solved by a fourth order Runge-Kutta method in MATLAB with a shooting technique for the initial guess. The influences of mixed temperature, depth dependent viscosity, and the rotation strength parameter on the flow field and temperature field generated on the plate surface are investigated. The derived results show direct impact in the problems of heat transfer in high speed computer disks (Herrero et al. [1]) and turbine rotor systems (Owen and Rogers [2]).

  7. Modeling and control of plasma rotation for NSTX using neoclassical toroidal viscosity and neutral beam injection

    SciTech Connect

    Goumiri, I. R.; Rowley, C. W.; Sabbagh, S. A.; Gates, D. A.; Gerhardt, S. P.; Boyer, M. D.; Andre, R.; Kolemen, E.; Taira, K.

    2016-02-19

    A model-based feedback system is presented to control plasma rotation in a magnetically confined toroidal fusion device, to maintain plasma stability for long-pulse operation. This research uses experimental measurements from the National Spherical Torus Experiment (NSTX) and is aimed at controlling plasma rotation using two different types of actuation: momentum from injected neutral beams and neoclassical toroidal viscosity generated by three-dimensional applied magnetic fields. Based on the data-driven model obtained, a feedback controller is designed, and predictive simulations using the TRANSP plasma transport code show that the controller is able to attain desired plasma rotation profiles given practical constraints on the actuators and the available measurements of rotation.

  8. Faster in-plane switching and reduced rotational viscosity characteristics in a graphene-nematic suspension

    NASA Astrophysics Data System (ADS)

    Basu, Rajratan; Kinnamon, Daniel; Skaggs, Nicole; Womack, James

    2016-05-01

    The in-plane switching (IPS) for a nematic liquid crystal (LC) was found to be considerably faster when the LC was doped with dilute concentrations of monolayer graphene flakes. Additional studies revealed that the presence of graphene reduced the rotational viscosity of the LC, permitting the nematic director to respond quicker in IPS mode on turning the electric field on. The studies were carried out with several graphene concentrations in the LC, and the experimental results coherently suggest that there exists an optimal concentration of graphene, allowing a reduction in the IPS response time and rotational viscosity in the LC. Above this optimal graphene concentration, the rotational viscosity was found to increase, and consequently, the LC no longer switched faster in IPS mode. The presence of graphene suspension was also found to decrease the LC's pretilt angle significantly due to the π-π electron stacking between the LC molecules and graphene flakes. To understand the π-π stacking interaction, the anchoring mechanism of the LC on a CVD grown monolayer graphene film on copper substrate was studied by reflected crossed polarized microscopy. Optical microphotographs revealed that the LC alignment direction depended on monolayer graphene's hexagonal crystal structure and its orientation.

  9. Faster in-plane switching and reduced rotational viscosity characteristics in a graphene-nematic suspension

    SciTech Connect

    Basu, Rajratan Kinnamon, Daniel; Skaggs, Nicole; Womack, James

    2016-05-14

    The in-plane switching (IPS) for a nematic liquid crystal (LC) was found to be considerably faster when the LC was doped with dilute concentrations of monolayer graphene flakes. Additional studies revealed that the presence of graphene reduced the rotational viscosity of the LC, permitting the nematic director to respond quicker in IPS mode on turning the electric field on. The studies were carried out with several graphene concentrations in the LC, and the experimental results coherently suggest that there exists an optimal concentration of graphene, allowing a reduction in the IPS response time and rotational viscosity in the LC. Above this optimal graphene concentration, the rotational viscosity was found to increase, and consequently, the LC no longer switched faster in IPS mode. The presence of graphene suspension was also found to decrease the LC's pretilt angle significantly due to the π-π electron stacking between the LC molecules and graphene flakes. To understand the π-π stacking interaction, the anchoring mechanism of the LC on a CVD grown monolayer graphene film on copper substrate was studied by reflected crossed polarized microscopy. Optical microphotographs revealed that the LC alignment direction depended on monolayer graphene's hexagonal crystal structure and its orientation.

  10. Studies of blood viscosity with a newly constructed rotational viscometer which operates via a desk top computer.

    PubMed

    Larsson, H; Odeberg, H; Bohlin, L

    1983-10-01

    Increasing interest is being shown in blood viscosity and the whole field of haemorheology. This study presents a newly constructed rotational Couette type viscometer which operates via a commercially available desk top computer and a digital plotter. The influence of haematocrit on blood viscosity is shown and the study also presents blood viscosity values of six to eight healthy men at 24 degrees C and 37 degrees C. At 37 degrees C values are shown both at natural haematocrit and at haematocrit 45%.

  11. Study of the confinement properties in a reversed-field pinch with mode rotation and gas fuelling

    NASA Astrophysics Data System (ADS)

    Cecconello, M.; Malmberg, J.-A.; Nielsen, P.; Pasqualotto, R.; Drake, J. R.

    2002-08-01

    An extensive investigation of the global confinement properties in different operating scenarios in the rebuilt EXTRAP T2R reversed-field pinch (RFP) experiment is reported here. In particular, the role of a fast gas puff valve system, used to control plasma density, on confinement is studied. Without gas puffing, the electron density decays below 0.5×1019 m-3. The poloidal beta varies between 5% and 15%, decreasing at large I/N. The energy confinement time ranges from 70 to 225 μs. With gas puffing, the density is sustained at ne≈1.5×1019 m-3. However, a general slight deterioration of the plasma performances is observed for the same values of I/N: the plasma becomes cooler and more radiative. The poloidal beta is comparable to that in the scenarios without puff but the energy confinement time drops ranging from 60 to 130 μs. The fluctuation level and the energy confinement time have been found to scale with the Lundquist number as S-0.05+/-0.07 and S0.5+/-0.1, respectively. Mode rotation is typical for all the discharges and rotation velocity is observed to increase with increasing electron diamagnetic velocity.

  12. Jeans instability of magnetized quantum plasma: Effect of viscosity, rotation and finite Larmor radius corrections

    SciTech Connect

    Jain, Shweta Sharma, Prerana; Chhajlani, R. K.

    2015-07-31

    The Jeans instability of self-gravitating quantum plasma is examined considering the effects of viscosity, finite Larmor radius (FLR) corrections and rotation. The analysis is done by normal mode analysis theory with the help of relevant linearized perturbation equations of the problem. The general dispersion relation is obtained using the quantum magneto hydrodynamic model. The modified condition of Jeans instability is obtained and the numerical calculations have been performed to show the effects of various parameters on the growth rate of Jeans instability.

  13. Ion heat pinch due to the magnetic drift resonance with the ion temperature gradient instability in a rotating plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Debing; Xu, Yingfeng; Wang, Shaojie

    2017-03-01

    The ion heat pinch due to the magnetic drift resonance with the ion temperature gradient instability is investigated by using the Lie-transform method. In a tokamak plasma with an equilibrium parallel flow, the total heat flux is found to direct inward with a strong flow shear. The proposed heat pinch can provide possible explanations for some experimental observations.

  14. The effects of rotational flow, viscosity, thickness, and shape on transonic flutter dip phenomena

    NASA Technical Reports Server (NTRS)

    Reddy, T. S. R.; Srivastava, Rakesh; Kaza, Krishna Rao V.

    1988-01-01

    The transonic flutter dip phenomena on thin airfoils, which are employed for propfan blades, is investigated using an integrated Euler/Navier-Stokes code and a two degrees of freedom typical section structural model. As a part of the code validation, the flutter characteristics of the NACA 64A010 airfoil are also investigated. In addition, the effects of artificial dissipation models, rotational flow, initial conditions, mean angle of attack, viscosity, airfoil thickness and shape on flutter are investigated. The results obtained with a Euler code for the NACA 64A010 airfoil are in reasonable agreement with published results obtained by using transonic small disturbance and Euler codes. The two artificial dissipation models, one based on the local pressure gradient scaled by a common factor and the other based on the local pressure gradient scaled by a spectral radius, predicted the same flutter speeds except in the recovery region for the case studied. The effects of rotational flow, initial conditions, mean angle of attack, and viscosity for the Reynold's number studied seem to be negligible or small on the minima of the flutter dip.

  15. Effects of polymers on the rotational viscosities of nematic liquid crystals and dynamics of field alignment

    SciTech Connect

    Kim, D.

    1993-12-31

    Many of the important physical phenomena exhibited by the nematic phase, such as its unusual flow properties and its responses to the electric and the magnetic fields, can be discussed regarding it as a continous medium. The Leslie-Erickson dynamic theory has the six dissipative coefficients from continuum model of liquid crystal. Parodi showed that only five of them are independent, when Onsagar`s reciprocal relations are used. One of these, which has no counterpart in the isotropic liquids, is the rotational viscosity co-efficient, {gamma}{sub 1}. The main objective of this project is to study the rotational viscosities of selected micellar nematic systems and the effect of dissolved polymers in micellar and thermotropic liqud crystals. We used rotating magnetic field method which allows one to determine {gamma}{sub 1} and the anisotropic magnetic susceptibility, {chi}{sub a}. For the ionic surfactant liquid crystals of SDS and KL systems used in this study, the rotational viscosity exhibited an extraordinary drop after reaching the highest values {gamma}{sub 1} as the temperature was lowered. This behavior is not observed in normal liquid crystals. But this phenomena can be attributed to the existence of nematic biaxial phase below the rod-like nematic N{sub c} phase. The pretransitional increase in {gamma}{sub 1} near the disk-like nematic to smectic-A phase transition of the pure CsPFO/H{sub 2}O systems are better understood with the help of mean-field models of W.L. McMillan. He predicted a critical exponent {nu} = {1/2} for the divergence of {gamma}{sub 1}. The polymer (PEO, molecular weight = 10{sup 5}) dissolved in CsPFO/H{sub 2}O system (which has 0.6% critical polymer concentration), suppressed the nematic to lamellar smectic phase transition in concentrated polymer solutions (0.75% and higher). In dilute polymer solutions with lower than 0.3% polyethylene-oxide, a linear increase of {gamma}{sub 1} is observed, which agrees with Brochard theory.

  16. Mantle viscosity, J2 and the nontidal acceleration of Earth rotation

    NASA Technical Reports Server (NTRS)

    Peltier, W. R.

    1985-01-01

    Recent interpretations of laser ranging for the LAGEOS satellite have rather conclusively established that the observed acceleration in the node of its orbit is just that expected to exist as a residual effect of the last deglaciation event which ended about 6000 years ago. The nontidal acceleration of rotation would be rather different than that observed if there were any significant melting of high latitude continental ice masses currently ongoing. The sensitivity of the expected nontidal acceleration to variations of several elements of the radial viscoelastic structure of the planet is explored using a new normal mode method for the computation of viscoelastic relaxation spectra. These calculations establish that the most important sensitivity is to variations in the mantle viscosity profile. Although the predicted nontidal acceleration does depend upon lithospheric thickness and on the elastic component of the radial structure, the dependence on these components of the structure is much weaker than it is upon mantle viscosity. The observed J sub 2 is therefore a particularly useful determinant of radial variations in the latter parameter.

  17. Effects of Polymers on the Rotational Viscosities of Nematic Liquid Crystals and Dynamics of Field Alignment.

    NASA Astrophysics Data System (ADS)

    Kim, Du-Rim

    Many of the important physical phenomena exhibited by the nematic phase, such as its unusual flow properties and its responses to the electric and the magnetic fields, can be discussed regarding it as a continuous medium. The Leslie-Erickson dynamic theory has the six dissipative coefficients from continuum model of liquid crystal. Parodi showed that only five of them are independent, when Onsagar's reciprocal relations are used. One of these, which has no counterpart in the isotropic liquids, is the rotational viscosity coefficient, gamma_1. The main objective of this project is to study the rotational viscosities of selected micellar nematic systems and the effect of dissolved polymers in micellar and thermotropic liquid crystals. We used rotating magnetic field method which allows one to determine gamma _1 and the anisotropic magnetic susceptibility, chi_{a}. For the ionic surfactant liquid crystals of SDS and KL systems used in this study, the rotational viscosity exhibited an extraordinary drop after reaching the highest value gamma_1 as the temperature was lowered. This behavior is not observed in normal liquid crystals. But this phenomena can be attributed to the existence of nematic biaxial phase below the rod-like nematic N_{c} phase. The pretransitional increase in gamma _1 near the disk-like nematic to smectic -A phase transition of the pure CsPFO H_2O systems are better understood with the help of mean-field models of W. L. McMillan. He predicted a critical exponent nu = -{1over 2} for the divergence of gamma_1. The polymer (PEO, molecular weight = 10 ^5) dissolved in CsPFO H_2O system (which has 0.6% critical polymer concentration), suppressed the nematic to lamellar smectic phase transition in concentrated polymer solutions (0.75% and higher). In dilute polymer solutions with lower than 0.3% polyethylene-oxide, a linear increase of gamma_1 is observed, which agrees with Brochard theory. The polymer solutions in thermotropic liquid crystal solvents

  18. Error Field Assessment from Driven Mode Rotation: Results from Extrap-T2R Reversed-Field-Pinch and Perspectives for ITER

    NASA Astrophysics Data System (ADS)

    Volpe, F. A.; Frassinetti, L.; Brunsell, P. R.; Drake, J. R.; Olofsson, K. E. J.

    2012-10-01

    A new ITER-relevant non-disruptive error field (EF) assessment technique not restricted to low density and thus low beta was demonstrated at the Extrap-T2R reversed field pinch. Resistive Wall Modes (RWMs) were generated and their rotation sustained by rotating magnetic perturbations. In particular, stable modes of toroidal mode number n=8 and 10 and unstable modes of n=1 were used in this experiment. Due to finite EFs, and in spite of the applied perturbations rotating uniformly and having constant amplitude, the RWMs were observed to rotate non-uniformly and be modulated in amplitude (in the case of unstable modes, the observed oscillation was superimposed to the mode growth). This behavior was used to infer the amplitude and toroidal phase of n=1, 8 and 10 EFs. The method was first tested against known, deliberately applied EFs, and then against actual intrinsic EFs. Applying equal and opposite corrections resulted in longer discharges and more uniform mode rotation, indicating good EF compensation. The results agree with a simple theoretical model. Extensions to tearing modes, to the non-uniform plasma response to rotating perturbations, and to tokamaks, including ITER, will be discussed.

  19. A Model of Peaked Density Profile and Inward Pinch in Tokamaks

    NASA Astrophysics Data System (ADS)

    Itoh, Sanae-I.

    1990-10-01

    A model theory of inward pinch and peaked density profile of ohmic discharges in the tokamak is presented. Ion anomalous viscosity in the presence of sheared rotation causes the drift across the magnetic field. Radial electric field, Er, can cause an inward pinch of electrons as well. The ratio of viscosities and the diffusion coefficient, the Prandtl number, determines the structures of Er and the density profile n(r) in a stationary state. In viscous plasmas, peaked profiles of both density and rotation velocity are expected. Reduction of edge neutrals changes the boundary condition and can induce further density peaking. Change of dEr/dr propagates into the center, causing ion viscous heating associated with the damping of velocity shear.

  20. CONDENSED MATTER: STRUCTURE, THERMAL AND MECHANICAL PROPERTIES: Rotational viscosity of a liquid crystal mixture: a fully atomistic molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Zhang, Ran; Peng, Zeng-Hui; Liu, Yong-Gang; Zheng, Zhi-Gang; Xuan, Li

    2009-10-01

    Fully atomistic molecular dynamics (MD) simulations at 293, 303 and 313 K have been performed for the four-component liquid crystal mixture, E7, using the software package Material Studio. Order parameters and orientational time correlation functions (TCFs) were calculated from MD trajectories. The rotational viscosity coefficients (RVCs) of the mixture were calculated using the Nemtsov-Zakharov and Fialkowski methods based on statistical-mechanical approaches. Temperature dependences of RVC and density were discussed in detail. Reasonable agreement between the simulated and experimental values was found.

  1. Peak neoclassical toroidal viscosity at low toroidal rotation in the DIII-D tokamak

    SciTech Connect

    Cole, A. J.; Callen, J. D.; Hegna, C. C.; Solomon, W. M.; Garofalo, A. M.; Lanctot, M. J.; Reimerdes, H.

    2011-05-15

    Observation of a theoretically predicted peak in the neoclassical toroidal viscous (NTV) force as a function of toroidal plasma rotation rate {Omega} is reported. The NTV was generated by applying n=3 magnetic fields from internal (I-)coils to low {Omega} plasmas produced with nearly balanced neutral beam injection. Locally, the peak corresponds to a toroidal rotation rate {Omega}{sub 0} where the radial electric field E{sub r} is near zero as determined by radial ion force balance.

  2. Viscosity structure of Earth's mantle inferred from rotational variations due to GIA process and recent melting events

    NASA Astrophysics Data System (ADS)

    Nakada, Masao; Okuno, Jun'ichi; Lambeck, Kurt; Purcell, Anthony

    2015-08-01

    We examine the geodetically derived rotational variations for the rate of change of degree-two harmonics of Earth's geopotential, skew5dot J_2, and true polar wander, combining a recent melting model of glaciers and the Greenland and Antarctic ice sheets taken from the IPCC 2013 Report (AR5) with two representative GIA ice models describing the last deglaciation, ICE5G and the ANU model developed at the Australian National University. Geodetically derived observations of skew4dot J_2 are characterized by temporal changes of -(3.7 ± 0.1) × 10-11 yr-1 for the period 1976-1990 and -(0.3 ± 0.1) × 10-11 yr-1 after ˜2000. The AR5 results make it possible to evaluate the recent melting of the major ice sheets and glaciers for three periods, 1900-1990, 1991-2001 and after 2002. The observed skew4dot J_2 and the component of skew4dot J_2 due to recent melting for different periods indicate a long-term change in skew4dot J_2-attributed to the Earth's response to the last glacial cycle-of -(6.0-6.5) × 10-11 yr-1, significantly different from the values adopted to infer the viscosity structure of the mantle in most previous studies. This is a main conclusion of this study. We next compare this estimate with the values of skew4dot J_2 predicted by GIA ice models to infer the viscosity structure of the mantle, and consequently obtain two permissible solutions for the lower mantle viscosity (ηlm), ˜1022 and (5-10) × 1022 Pa s, for both adopted ice models. These two solutions are largely insensitive to the lithospheric thickness and upper mantle viscosity as indicated by previous studies and relatively insensitive to the viscosity structure of the D″ layer. The ESL contributions from the Antarctic ice sheet since the last glacial maximum (LGM) for ICE5G and ANU are about 20 and 30 m, respectively, but glaciological reconstructions of the Antarctic LGM ice sheet have suggested that its ESL contribution may have been less than ˜10 m. The GIA-induced skew4dot J_2 for GIA

  3. Conditional stability for thermal convection in a rotating couple-stress fluid saturating a porous medium with temperature and pressure dependent viscosity

    NASA Astrophysics Data System (ADS)

    Sunil; Choudhary, Shalu; Mahajan, Amit

    2013-08-01

    A nonlinear stability threshold for rotation in a couple-stress fluid heated from below saturating a porous medium with temperature and pressure dependent viscosity is exactly the same as the linear instability boundary. This optimal result is important because it shows that linearized instability theory has captured completely the physics of the onset of convection. The effects of couple-stress parameter, variable dependent viscosity, medium permeability, Taylor number and Darcy-Brinkman number on the onset of convection are also analysed.

  4. Characteristics of Neoclassical Toroidal Viscosity in NSTX and KSTAR for Rotation Control and the Evaluation of Plasma Response

    NASA Astrophysics Data System (ADS)

    Sabbagh, S. A.; Berkery, J. W.; Park, Y. S.; Bell, R. E.; Gates, D. A.; Gerhardt, S. P.; Goumiri, I.; Evans, T. E.; Ferraro, N.; Jeon, Y. M.; Ko, W.; Shaing, K. C.; Sun, Y.

    2014-10-01

    Three-dimensional magnetic fields producing non-resonant magnetic braking allow control of the plasma rotation profile, ωφ, in tokamaks. Experimental angular momentum alteration created by 3D field configurations with dominant n = 2 and n = 3 components in NSTX is compared to theoretical neoclassical toroidal viscosity (NTV) torque density profiles, TNTV. Large radial variations of TNTV are typically found when flux surface displacements are computed using ideal MHD assumptions. In contrast, experimentally measured TNTV does not show strong torque localization. This may be explained by ion banana width orbit-averaging effects. A favorable characteristic for ωφ control clearly illustrated by KSTAR experiments is the lack of hysteresis of ωφ when altered by non-resonant NTV. Results from a model-based rotation controller designed using NBI and NTV from the applied 3D field as actuators are shown. The dependence of TNTV on δB2 significantly constrains the allowable field amplification in plasma response models when compared to experiment. Initial analysis shows that the single fluid model in the M3D-C1 resistive MHD code produces a flux surface-averaged δB consistent with the experimentally measured TNTV. Supported by US DOE Contracts DE-FG02-99ER54524 and DE-AC02-09CH11466.

  5. Effects of neoclassical toroidal viscosity induced by the intrinsic error fields and toroidal field ripple on the toroidal rotation in tokamaks

    NASA Astrophysics Data System (ADS)

    Lee, H. H.; Seol, J.; Ko, W. H.; Terzolo, L.; Aydemir, A. Y.; In, Y.; Ghim, Y.-c.; Lee, S. G.

    2016-08-01

    Effects of neoclassical toroidal viscosity (NTV) induced by intrinsic error fields and toroidal field ripple on cocurrent toroidal rotation in H-mode tokamak plasmas are investigated. It is expected that large NTV torque can be localized at the edge region through the 1/ν-regime in the vicinity of E r ˜ 0 in the cocurrent rotating H-mode plasma. Numerical simulation on toroidal rotation demonstrates that the edge localized NTV torque determined by the intrinsic error fields and toroidal field ripples in the level of most tokamaks can damp the toroidal rotation velocity over the whole region while reducing the toroidal rotation pedestal which is clearly observed in Korea Superconducting Tokamak Advanced Research (KSTAR) tokamak. It is found that the NTV torque changes the toroidal rotation gradient in the pedestal region dramatically, but the toroidal rotation profile in the core region responds rigidly without a change in the gradient. On the other hand, it shows that the NTV torque induced by the intrinsic error fields and toroidal field ripple in the level of the KSTAR tokamak, which are expected to be smaller than most tokamaks by at least one order of magnitude, is negligible in determining the toroidal rotation velocity profile. Experimental observation on the toroidal rotation change by the externally applied nonaxisymmetric magnetic fields on KSTAR also suggests that NTV torque arising from nonaxisymmetric magnetic fields can damp the toroidal rotation over the whole region while diminishing the toroidal rotation pedestal.

  6. The effect of CdSe/ZnS quantum dots on the rotational viscosity and charge carrier concentration of a nematic liquid crystal

    NASA Astrophysics Data System (ADS)

    Shcherbinin, D. P.; Konshina, E. A.; Solodkov, D. E.

    2015-08-01

    The addition of CdSe/ZnS quantum dots (QDs) with a core diameter of 3.5 nm at a concentration of 10 wt % leads to a 2.5-fold increase in the dynamic rotational viscosity of a 5CB nematic liquid crystal (NLC). A comparison of the diffusion currents in NLC cells filled with pure 5CB and a suspension with QDs shows evidence of an increase in the concentration of charge carriers in the latter case.

  7. Hall viscosity

    NASA Astrophysics Data System (ADS)

    Read, Nicholas

    2015-03-01

    Viscosity is a transport coefficient relating to transport of momentum, and usually thought of as the analog of friction that occurs in fluids and solids. More formally, it is the response of the stress to the gradients of the fluid velocity field, or to the rate of change of strain (derivatives of displacement from a reference state). In general, viscosity is described by a fourth-rank tensor. Invoking rotation invariance, it reduces to familiar shear and bulk viscosity parts, which describe dissipation, but it can also contain an antisymmetric part, analogous to the Hall conductivity part of the conductivity tensor. In two dimensions this part is a single number, the Hall viscosity. Symmetry of the system under time reversal (or, in two dimensions, reflections) forces it to vanish. In quantum fluids with a gap in the bulk energy spectrum and which lack both time reversal and reflection symmetries the Hall viscosity can be nonzero even at zero temperature. For integer quantum Hall states, it was first calculated by Avron, Seiler, and Zograf, using a Berry curvature approach, analogous to the Chern number for Hall conductivity. In 2008 this was extended by the present author to fractional quantum Hall states and to BCS states in two dimensions. I found that the general result is given by a simple formula ns / 2 , where n is the particle number density, and s is the ``orbital spin'' per particle. The spin s is also related to the shift S, which enters the relation between particle number and magnetic flux needed to put the ground state on a surface of non-trivial topology with introducing defect excitations, by S = 2 s ; the connection was made by Wen and Zee. The values of s and S are rational numbers, and are robust--unchanged under perturbations that do not cause the bulk energy gap to collapse--provided rotation as well as translation symmetry are maintained. Hall viscosity can be measured in principle, though a simple way to do so is lacking. It enters various

  8. Diffusion-Controlled Rotation of Triptycene in a Metal–Organic Framework (MOF) Sheds Light on the Viscosity of MOF-Confined Solvent

    PubMed Central

    2016-01-01

    Artificial molecular machines are expected to operate under conditions of very low Reynolds numbers with inertial forces orders of magnitude smaller than viscous forces. While these conditions are relatively well understood in bulk fluids, opportunities to assess the role of viscous forces in confined crystalline media are rare. Here we report one such example of diffusion-controlled rotation in crystals and its application as a probe for viscosity of MOF-confined solvent. We describe the preparation and characterization of three pillared paddlewheel MOFs, with 9,10-bis(4-pyridylethynyl)triptycene 3 as a pillar and molecular rotator, and three axially substituted dicarboxylate linkers with different lengths and steric bulk. The noncatenated structure with a bulky dicarboxylate linker (UCLA-R3) features a cavity filled by 10 molecules of N,N-dimethylformamide (DMF). Solid-state 2H NMR analysis performed between 293 and 343 K revealed a fast 3-fold rotation of the pillar triptycene group with the temperature dependence consistent with a site exchange process determined by rotator-solvent interactions. The dynamic viscosity of the MOF-confined solvent was estimated to be 13.3 N·s/m2 (or Pa·s), which is 4 orders of magnitude greater than that of bulk DMF (8.2 × 10–4 N·s/m2), and comparable to that of honey. PMID:27725958

  9. The effect of screw rotating speed on mass flow rate, temperature, viscosity, mooney scorch time anddie swell of cold feed rubber blending prepared by qsm 200 extruder machine

    NASA Astrophysics Data System (ADS)

    Elmiawan, P.; Saryanto, H.; Sebayang, D.

    2017-05-01

    The effect of screw rotating speed on cold feed rubber blending production were evaluated. The specimens were prepared by using QSM 200 extruding machine with variable screw rotating speed 4, 6, 8, 10, 12, 16 and 20 RPM. The temperature set in the screw and head of the barrel was around 80 °C by using Temperature Controll Unit (TCU), and was set around 70°C in zone 1 and 2. Mooney Viscometer was used to evaluate the viscosity and Mooney Scorch Time of cold rubber blending before and after extruding process. In addition, the dynamic rubber process analyzer was used to evaluate the Die Swell of rubber blending after extruding process. The result indicated that the increase of screw rotating speed has a significant effect to increase the flow rate, temperature and the viscosity of the rubber blending. Otherwise, the Mooney Scorch Time (MST) increases due to the decrease of the screw rotating speed. It does not have a significant effect to the die swell of rubber blending.

  10. Simultaneous feedback control of plasma rotation and stored energy on NSTX-U using neoclassical toroidal viscosity and neutral beam injection.

    PubMed

    Goumiri, I R; Rowley, C W; Sabbagh, S A; Gates, D A; Boyer, M D; Gerhardt, S P; Kolemen, E; Menard, J E

    2017-05-01

    A model-based feedback system is presented enabling the simultaneous control of the stored energy through βn and the toroidal rotation profile of the plasma in National Spherical Torus eXperiment Upgrade device. Actuation is obtained using the momentum from six injected neutral beams and the neoclassical toroidal viscosity generated by applying three-dimensional magnetic fields. Based on a model of the momentum diffusion and torque balance, a feedback controller is designed and tested in closed-loop simulations using TRANSP, a time dependent transport analysis code, in predictive mode. Promising results for the ongoing experimental implementation of controllers are obtained.

  11. Simultaneous feedback control of plasma rotation and stored energy on NSTX-U using neoclassical toroidal viscosity and neutral beam injection

    NASA Astrophysics Data System (ADS)

    Goumiri, I. R.; Rowley, C. W.; Sabbagh, S. A.; Gates, D. A.; Boyer, M. D.; Gerhardt, S. P.; Kolemen, E.; Menard, J. E.

    2017-05-01

    A model-based feedback system is presented enabling the simultaneous control of the stored energy through βn and the toroidal rotation profile of the plasma in National Spherical Torus eXperiment Upgrade device. Actuation is obtained using the momentum from six injected neutral beams and the neoclassical toroidal viscosity generated by applying three-dimensional magnetic fields. Based on a model of the momentum diffusion and torque balance, a feedback controller is designed and tested in closed-loop simulations using TRANSP, a time dependent transport analysis code, in predictive mode. Promising results for the ongoing experimental implementation of controllers are obtained.

  12. RETRACTION: Unsteady flow and heat transfer of viscous incompressible fluid with temperature-dependent viscosity due to a rotating disc in a porous medium

    NASA Astrophysics Data System (ADS)

    Attia, H. A.

    2007-04-01

    It has come to the attention of the Institute of Physics that this article should not have been submitted for publication owing to its plagiarism of an earlier paper (Hossain A, Hossain M A and Wilson M 2001 Unsteady flow of viscous incompressible fluid with temperature-dependent viscosity due to a rotating disc in presence of transverse magnetic field and heat transfer Int. J. Therm. Sci. 40 11-20). Therefore this article has been retracted by the Institute of Physics and by the author, Hazem Ali Attia.

  13. Simultaneous feedback control of plasma rotation and stored energy on NSTX-U using neoclassical toroidal viscosity and neutral beam injection

    DOE PAGES

    Goumiri, I. R.; Rowley, C. W.; Sabbagh, S. A.; ...

    2017-02-23

    In this study, a model-based feedback system is presented enabling the simultaneous control of the stored energy through βn and the toroidal rotation profile of the plasma in National Spherical Torus eXperiment Upgrade device. Actuation is obtained using the momentum from six injected neutral beams and the neoclassical toroidal viscosity generated by applying three-dimensional magnetic fields. Based on a model of the momentum diffusion and torque balance, a feedback controller is designed and tested in closed-loop simulations using TRANSP, a time dependent transport analysis code, in predictive mode. Promising results for the ongoing experimental implementation of controllers are obtained.

  14. Helical-D pinch

    SciTech Connect

    Schaffer, M.J.

    1997-08-01

    A stabilized pinch configuration is described, consisting of a D-shaped plasma cross section wrapped tightly around a guiding axis. The {open_quotes}helical-D{close_quotes} geometry produces a very large axial (toroidal) transform of magnetic line direction that reverses the pitch of the magnetic lines without the need of azimuthal (poloidal) plasma current. Thus, there is no need of a {open_quotes}dynamo{close_quotes} process and its associated fluctuations. The resulting configuration has the high magnetic shear and pitch reversal of the reversed field pinch (RFP). (Pitch = P = qR, where R = major radius). A helical-D pinch might demonstrate good confinement at q << 1.

  15. Rotation of Magnetization Derived from Brownian Relaxation in Magnetic Fluids of Different Viscosity Evaluated by Dynamic Hysteresis Measurements over a Wide Frequency Range.

    PubMed

    Ota, Satoshi; Kitaguchi, Ryoichi; Takeda, Ryoji; Yamada, Tsutomu; Takemura, Yasushi

    2016-09-10

    The dependence of magnetic relaxation on particle parameters, such as the size and anisotropy, has been conventionally discussed. In addition, the influences of external conditions, such as the intensity and frequency of the applied field, the surrounding viscosity, and the temperature on the magnetic relaxation have been researched. According to one of the basic theories regarding magnetic relaxation, the faster type of relaxation dominates the process. However, in this study, we reveal that Brownian and Néel relaxations coexist and that Brownian relaxation can occur after Néel relaxation despite having a longer relaxation time. To understand the mechanisms of Brownian rotation, alternating current (AC) hysteresis loops were measured in magnetic fluids of different viscosities. These loops conveyed the amplitude and phase delay of the magnetization. In addition, the intrinsic loss power (ILP) was calculated using the area of the AC hysteresis loops. The ILP also showed the magnetization response regarding the magnetic relaxation over a wide frequency range. To develop biomedical applications of magnetic nanoparticles, such as hyperthermia and magnetic particle imaging, it is necessary to understand the mechanisms of magnetic relaxation.

  16. Rotation of Magnetization Derived from Brownian Relaxation in Magnetic Fluids of Different Viscosity Evaluated by Dynamic Hysteresis Measurements over a Wide Frequency Range

    PubMed Central

    Ota, Satoshi; Kitaguchi, Ryoichi; Takeda, Ryoji; Yamada, Tsutomu; Takemura, Yasushi

    2016-01-01

    The dependence of magnetic relaxation on particle parameters, such as the size and anisotropy, has been conventionally discussed. In addition, the influences of external conditions, such as the intensity and frequency of the applied field, the surrounding viscosity, and the temperature on the magnetic relaxation have been researched. According to one of the basic theories regarding magnetic relaxation, the faster type of relaxation dominates the process. However, in this study, we reveal that Brownian and Néel relaxations coexist and that Brownian relaxation can occur after Néel relaxation despite having a longer relaxation time. To understand the mechanisms of Brownian rotation, alternating current (AC) hysteresis loops were measured in magnetic fluids of different viscosities. These loops conveyed the amplitude and phase delay of the magnetization. In addition, the intrinsic loss power (ILP) was calculated using the area of the AC hysteresis loops. The ILP also showed the magnetization response regarding the magnetic relaxation over a wide frequency range. To develop biomedical applications of magnetic nanoparticles, such as hyperthermia and magnetic particle imaging, it is necessary to understand the mechanisms of magnetic relaxation. PMID:28335297

  17. Current redistribution and generation of kinetic energy in the stagnated Z pinch.

    PubMed

    Ivanov, V V; Anderson, A A; Papp, D; Astanovitskiy, A L; Talbot, B R; Chittenden, J P; Niasse, N

    2013-07-01

    The structure of magnetic fields was investigated in stagnated wire-array Z pinches using a Faraday rotation diagnostic at the wavelength of 266 nm. The distribution of current in the pinch and trailing material was reconstructed. A significant part of current can switch from the main pinch to the trailing plasma preheated by x-ray radiation of the pinch. Secondary implosions of trailing plasma generate kinetic energy and provide enhanced heating and radiation of plasma at stagnation. Hot spots in wire-array Z pinches also provide enhanced radiation of the Z pinch. A collapse of a single hot spot radiates 1%-3% of x-ray energy of the Z pinch with a total contribution of hot spots of 10%-30%.

  18. CUSP-PINCH DEVICE

    DOEpatents

    Baker, W.R.; Watteau, J.P.H.

    1962-06-01

    An ion-electron plasma heating device of the pinch tube class is designed with novel means for counteracting the instabilities of an ordinary linear pinch discharge. A plasma-forming discharge is created between two spacedapart coaxial electiodes through a gas such as deuterium. A pair of spaced coaxial magnetic field coils encircle the discharge and carry opposing currents so that a magnetic field having a cuspate configuration is created around the plasma, the field being formed after the plasma has been established but before significant instability arises. Thus, containment time is increased and intensified heating is obtained. In addition to the pinch compression heating additional heating is obtained by high-frequency magnetic field modulation. (AEC)

  19. Overview of results from the MST reversed field pinch experiment

    NASA Astrophysics Data System (ADS)

    Sarff, J. S.; Almagri, A. F.; Anderson, J. K.; Borchardt, M.; Carmody, D.; Caspary, K.; Chapman, B. E.; Den Hartog, D. J.; Duff, J.; Eilerman, S.; Falkowski, A.; Forest, C. B.; Goetz, J. A.; Holly, D. J.; Kim, J.-H.; King, J.; Ko, J.; Koliner, J.; Kumar, S.; Lee, J. D.; Liu, D.; Magee, R.; McCollam, K. J.; McGarry, M.; Mirnov, V. V.; Nornberg, M. D.; Nonn, P. D.; Oliva, S. P.; Parke, E.; Reusch, J. A.; Sauppe, J. P.; Seltzman, A.; Sovinec, C. R.; Stephens, H.; Stone, D.; Theucks, D.; Thomas, M.; Triana, J.; Terry, P. W.; Waksman, J.; Bergerson, W. F.; Brower, D. L.; Ding, W. X.; Lin, L.; Demers, D. R.; Fimognari, P.; Titus, J.; Auriemma, F.; Cappello, S.; Franz, P.; Innocente, P.; Lorenzini, R.; Martines, E.; Momo, B.; Piovesan, P.; Puiatti, M.; Spolaore, M.; Terranova, D.; Zanca, P.; Belykh, V.; Davydenko, V. I.; Deichuli, P.; Ivanov, A. A.; Polosatkin, S.; Stupishin, N. V.; Spong, D.; Craig, D.; Harvey, R. W.; Cianciosa, M.; Hanson, J. D.

    2013-10-01

    An overview of recent results from the MST programme on physics important for the advancement of the reversed field pinch (RFP) as well as for improved understanding of toroidal magnetic confinement more generally is reported. Evidence for the classical confinement of ions in the RFP is provided by analysis of impurity ions and energetic ions created by 1 MW neutral beam injection (NBI). The first appearance of energetic-particle-driven modes by NBI in a RFP plasma is described. MST plasmas robustly access the quasi-single-helicity state that has commonalities to the stellarator and ‘snake’ formation in tokamaks. In MST the dominant mode grows to 8% of the axisymmetric field strength, while the remaining modes are reduced. Predictive capability for tearing mode behaviour has been improved through nonlinear, 3D, resistive magnetohydrodynamic computation using the measured resistivity profile and Lundquist number, which reproduces the sawtooth cycle dynamics. Experimental evidence and computational analysis indicates two-fluid effects, e.g., Hall physics and gyro-viscosity, are needed to understand the coupling of parallel momentum transport and current profile relaxation. Large Reynolds and Maxwell stresses, plus separately measured kinetic stress, indicate an intricate momentum balance and a possible origin for MST's intrinsic plasma rotation. Gyrokinetic analysis indicates that micro-tearing modes can be unstable at high beta, with a critical gradient for the electron temperature that is larger than for tokamak plasmas by roughly the aspect ratio.

  20. Viscosity Measurement for Tellurium Melt

    NASA Technical Reports Server (NTRS)

    Lin, Bochuan; Li, Chao; Ban, Heng; Scripa, Rosalia N.; Su, Ching-Hua; Lehoczky, Sandor L.

    2006-01-01

    The viscosity of high temperature Te melt was measured using a new technique in which a rotating magnetic field was applied to the melt sealed in a suspended ampoule, and the torque exerted by rotating melt flow on the ampoule wall was measured. Governing equations for the coupled melt flow and ampoule torsional oscillation were solved, and the viscosity was extracted from the experimental data by numerical fitting. The computational result showed good agreement with experimental data. The melt velocity transient initiated by the rotating magnetic field reached a stable condition quickly, allowing the viscosity and electrical conductivity of the melt to be determined in a short period.

  1. Viscosity Measurement for Tellurium Melt

    NASA Technical Reports Server (NTRS)

    Lin, Bochuan; Li, Chao; Ban, Heng; Scripa, Rosalia N.; Su, Ching-Hua; Lehoczky, Sandor L.

    2006-01-01

    The viscosity of high temperature Te melt was measured using a new technique in which a rotating magnetic field was applied to the melt sealed in a suspended ampoule, and the torque exerted by rotating melt flow on the ampoule wall was measured. Governing equations for the coupled melt flow and ampoule torsional oscillation were solved, and the viscosity was extracted from the experimental data by numerical fitting. The computational result showed good agreement with experimental data. The melt velocity transient initiated by the rotating magnetic field reached a stable condition quickly, allowing the viscosity and electrical conductivity of the melt to be determined in a short period.

  2. The effects of screw rotation speed on viscosity, mooney scorch time and dieswell of hot-feed blending rubber-compound prefared by gs/w 250 extruder machine

    NASA Astrophysics Data System (ADS)

    Zohari, A.; Saryanto, H.; Sebayang, D.

    2017-05-01

    This paper is an experimental study that aimed at figuring out the effect of screw rotation speed on the viscosity, mooney scorch time and dieswell of rubber-compound blending prepared by GS/w 250 Extruder Machine to determine the appropriate parameter setting for the expected rubber-compond specification. The screw rotation speed was set at 10, 20, 40 RPM and the three-zone temperature of the screw extruder was set by the TCU. Viscosity and Mooney Scorch Time (MST)of rubber-compound were evaluated before and after extruding processusing the Mooney Viscometer test equipment. The Die Swell of the rubber-compound were evaluated after blending process using the dynamic rubber process analyzer. The result showed that the Viscosity and Mooney Scorch Timeof rubber-compound before extuder process was around 56.59 mooney and 19.69 minute. After extruding process, the value of Mooney Viscosity was consecutively around 51.55, 51.25, 50.55 mooney and the value of Die Swell was consecutively around 0.493, 0.536, 0.553Lb-in. The value of Mooney Scorch Time was consecutively around 19.00, 15.47, 17.37 minute. The results indicates that, the increase of screw rotation speed decrease the Viscosityand increase the Die Swell of the rubber-compound.

  3. Pinch-off syndrome

    PubMed Central

    Cho, Jin-Beom; Park, Il-Young; Sung, Ki-Young; Baek, Jong-Min; Lee, Jun-Hyun

    2013-01-01

    Subclavian venous catheterization was previously frequently performed, but because of life-threatening complications such as hemothorax, pneumothorax, mediastinal hematoma, and myocardial injury, its use has become less common. However, this practice has some advantages in patient mobility, secured dressing, and rapidity and adequacy of vascular access. In some situations where patient comfort is an especially important consideration, such as with totally implantable venous port insertion for chemotherapy, the subclavian route can be a good choice if an experienced and well-trained faculty is available. The authors have had recent experience with pinch-off syndrome-in other words, spontaneous catheter fracture-in 3 patients who had undergone venous port implantation through the right subclavian route. Through these cases, we intend to review the dangers of subclavian venous catheterization, the causes of pinch-off syndrome, and its clinical presentation, progress, treatments, and prevention. PMID:24020024

  4. Compact Pinch Welder

    NASA Technical Reports Server (NTRS)

    Morgan, Gene E.; Thomas, Clark S.

    1991-01-01

    Spot welder designed for bonding insulated metal strips together. Compact, measuring only about 33.5 cm in its largest linear dimension. Pinch welder clamps electrodes on weldments with strong, repeatable force. Compressed air supplied through fitting on one handle. Small switch on same handle starts welding process when operator presses it with trigger. Provides higher, more repeatable clamping force than manually driven gun and thus produces weld joints of higher quality. Light in weight and therefore positioned precisely by operator.

  5. Evolution equations for magnetic islands in a reversed field pinch

    NASA Astrophysics Data System (ADS)

    Yu, Edmund Po-Ning

    We derive a coupled set of equations, consisting of a partial differential equation (PDE) and several ordinary differential equations (ODEs), which govern the phase evolution of a nonlinear magnetic island chain in a reversed field pinch (RFP), subject to the braking torque due to eddy currents excited in a resistive vacuum vessel and the locking torque due to an external resonant magnetic perturbation (RMP). We first use our phase evolution equations to examine the locking behavior of the island chain; such a study is of interest because tearing modes and their associated magnetic islands generate a toroidally localized magnetic structure (slinky mode) which, if locked to a static RMP, can seriously degrade plasma confinement. A key component of our analysis is the reduction of the original PDE/ODE description of phase evolution to a much simpler and physically transparent (coupled) set of first order ODEs, which possess the novel feature that the radial extent of the region of plasma which co-rotates with the island chain is determined self-consistently, by viscosity. Using these equations, we develop a comprehensive theory of the influence of a resistive vacuum vessel on error-field locking and unlocking thresholds. Our ODE description of phase evolution is limited in that it cannot account for island width evolution, or time-variation in the RMP. Our final step, then, is to develop an extension of our simple phase evolution equations which, when coupled with a (Rutherford-like) island width evolution equation, can completely describe the island chain dynamics in the presence of a rotating RMP with programmable amplitude and frequency waveforms. Consequently, we can use these island evolution equations to model magnetic feedback experiments.

  6. Z-Pinch Fusion Propulsion

    NASA Technical Reports Server (NTRS)

    Miernik, Janie

    2011-01-01

    Fusion-based nuclear propulsion has the potential to enable fast interplanetary transportation. Shorter trips are better for humans in the harmful radiation environment of deep space. Nuclear propulsion and power plants can enable high Ispand payload mass fractions because they require less fuel mass. Fusion energy research has characterized the Z-Pinch dense plasma focus method. (1) Lightning is form of pinched plasma electrical discharge phenomena. (2) Wire array Z-Pinch experiments are commonly studied and nuclear power plant configurations have been proposed. (3) Used in the field of Nuclear Weapons Effects (NWE) testing in the defense industry, nuclear weapon x-rays are simulated through Z-Pinch phenomena.

  7. Fusion with Z-pinches

    SciTech Connect

    Cook, D.

    1998-06-01

    In the past thirty-six months, great progress has been made in x-ray production using high-current z-pinches. Today, the x-ray energy and power output of the Z accelerator (formerly PBFA-II) is the largest available in the laboratory. These z-pinch x-ray sources have the potential to drive high-yield ICF reactions at affordable cost if several challenging technical problems can be overcome. In this paper, the recent technical progress with Z-pinches will be described, and a technical strategy for achieving high-yield ICF with z-pinches will be presented.

  8. Turbulent Equipartition Theory of Toroidal Momentum Pinch

    SciTech Connect

    T.S. Hahm, P.H. Diamond, O.D. Gurcan, and G. Rewaldt

    2008-01-31

    The mode-independet part of magnetic curvature driven turbulent convective (TuroCo) pinch of the angular momentum density [Hahm et al., Phys. Plasmas 14,072302 (2007)] which was originally derived from the gyrokinetic equation, can be interpreted in terms of the turbulent equipartition (TEP) theory. It is shown that the previous results can be obtained from the local conservation of "magnetically weighted angular momentum density," nmi U|| R/B2, and its homogenization due to turbulent flows. It is also demonstrated that the magnetic curvature modification of the parallel acceleration in the nonlinear gyrokinetic equation in the laboratory frame, which was shown to be responsible for the TEP part of the TurCo pinch of angular momentum density in the previous work, is closely related to the Coriolis drift coupling to the perturbed electric field. In addition, the origin of the diffusive flux in the rotating frame is highlighted. Finally, it is illustratd that there should be a difference in scalings between the momentum pinch originated from inherently toroidal effects and that coming from other mechanisms which exist in a simpler geometry.

  9. PINCHED PLASMA REACTOR

    DOEpatents

    Phillips, J.A.; Suydam, R.; Tuck, J.L.

    1961-07-01

    BS>A plasma confining and heating reactor is described which has the form of a torus with a B/sub 2/ producing winding on the outside of the torus and a helical winding of insulated overlapping tunns on the inside of the torus. The inner helical winding performs the double function of shielding the plasma from the vitreous container and generating a second B/sub z/ field in the opposite direction to the first B/sub z/ field after the pinch is established.

  10. Rotations

    Treesearch

    John R. Jones; Wayne D. Shepperd

    1985-01-01

    The rotation, in forestry, is the planned number of years between formation of a crop or stand and its final harvest at a specified stage of maturity (Ford-Robertson 1971). The rotation used for many species is the age of culmination of mean usable volume growth [net mean annual increment (MAI)]. At that age, usable volume divided by age reaches its highest level. That...

  11. Conditional stability for thermal convection in a rotating couple-stress fluid saturating a porous media with temperature- and pressure-dependent viscosity using a thermal non-equilibrium model

    NASA Astrophysics Data System (ADS)

    Sunil; Choudhary, Shalu; Mahajan, Amit

    2014-06-01

    A nonlinear stability threshold for convection in a rotating couple-stress fluid saturating a porous medium with temperature- and pressure-dependent viscosity using a thermal non-equilibrium model is found to be exactly the same as the linear instability boundary. This optimal result is important because it shows that linear theory has completely captured the physics of the onset of convection. The effects of couple-stress fluid parameter F, temperature- and pressure-dependent viscosity Γ, interface heat transfer coefficient H, Taylor number TA, Darcy-Brinkman number D˜a, and porosity modified conductivity ratio γ on the onset of convection have been investigated. Asymptotic analysis for both small and large values of interface heat transfer coefficient H is also presented. An excellent agreement is found between the exact solutions and asymptotic solutions.

  12. Linking natural microstructures with numerical modeling of pinch-and-swell structures

    NASA Astrophysics Data System (ADS)

    Peters, Max; Berger, Alfons; Herwegh, Marco; Regenauer-Lieb, Klaus

    2016-04-01

    For a variety of geological problems, the change from homogeneous to localized deformation and the establishment of steady-state conditions are equally important. Here, we show that pinch-and-swell structures are ideal candidates for the study of the switch in deformation style and mechanism during ductile creep. We present an interdisciplinary approach to the onset of pinch-and-swell structures and to the flow conditions during pre- to post-localization stages in ductile rocks. For this reason, naturally boudinaged calcite veins, embedded in a calc-mylonite, and their microfabrics were investigated quantitatively. Remnants of slightly deformed calcite hosts build up the swells, showing twinning and minor dislocation glide as crystal plastic deformation mechanisms which are accompanied by subgrain rotation recrystallization (SGR). Towards the pinches, we find a gradient of severe grain size reduction through progressive SGR, developing a characteristic dislocation creep crystallographic preferred orientation (CPO). Along this gradient, the finest recrystallized calcite grains appear randomly oriented, expressed by a "smearing-out" of the CPO and missing systematics of misorientation angles in the most extended areas. We interpret this microstructure as a switch from dislocation dominated creep to grain boundary sliding processes. Further, we show that the onset of boudinage is independent on both the original orientation and grain size of calcite hosts. We implemented these microstructural observations into a layered elasto-visco-plastic finite element framework, tracing variations in grain size (Peters et al., 2015). We base the microstructural evolution on thermo-mechanical-chemical principles and end-member flow laws (Herwegh et al., 2014). The simulated pinch-and-swell structures indicate that low strain rates in the swells favor dislocation creep, whereas accelerated rates provoke continuous grain size reduction allowing strain accommodation by diffusion creep

  13. Instability of high-frequency acoustic waves in accretion disks with turbulent viscosity

    NASA Astrophysics Data System (ADS)

    Khoperskov, A. V.; Khrapov, S. S.

    1999-05-01

    The dynamics of linear perturbations in a differentially rotating accretion disk with a non-homogeneous vertical structure is investigated. We find that turbulent viscosity results in instability of both pinching oscillations, and bending modes. Not only the low-frequency fundamental modes, but also the high-frequency reflective harmonics appear to be unstable. The question of the limits of applicability of the thin disk model (MTD) is also investigated. Some differences in the dispersion properties of the MTD and of the three-dimensional model appear for wave numbers k <~ (1-3)/h (h is the half-thickness of a disk). In the long-wavelength limit, the relative difference between the eigenfrequencies of the unstable acoustic mode in the 3D-model and the MTD is smaller than 5%. In the short wavelength case (kh > 1) these differences are increased.

  14. LETTER TO THE EDITOR: Anisotropy of ion temperature in a reversed-field-pinch plasma

    NASA Astrophysics Data System (ADS)

    Sasaki, K.; Hörling, P.; Fall, T.; Brzozowski, J. H.; Brunsell, P.; Hokin, S.; Tennfors, E.; Sallander, J.; Drake, J. R.; Inoue, N.; Morikawa, J.; Ogawa, Y.; Yoshida, Z.

    1997-03-01

    Anomalous heating of ions has been observed in the EXTRAP-T2 reversed-field-pinch (RFP) plasma. Ions are heated primarily in the parallel direction (with respect to the magnetic field), resulting in an appreciable anisotropy of the ion temperature. This observation suggests that the magnetohydrodynamic fluctuations are dissipated primarily by the ion viscosity.

  15. Increasing plasma parameters using sheared flow stabilization of a Z-pinch

    NASA Astrophysics Data System (ADS)

    Shumlak, U.; Nelson, B. A.; Claveau, E. L.; Forbes, E. G.; Golingo, R. P.; Hughes, M. C.; Oberto, R. J.; Ross, M. P.; Weber, T. R.

    2017-05-01

    The ZaP and ZaP-HD Flow Z-pinch experiments at the University of Washington have successfully demonstrated that sheared plasma flows can be used as a stabilization mechanism over a range of parameters that has not previously been accessible to long-lived Z-pinch configurations. The stabilization is effective even when the plasma column is compressed to small radii, producing predicted increases in magnetic field and electron temperature. The flow shear value, extent, and duration are shown to be consistent with theoretical models of the plasma viscosity, which places a design constraint on the maximum axial length of a sheared flow stabilized Z-pinch. Measurements of the magnetic field topology indicate simultaneous azimuthal symmetry and axial uniformity along the entire 100 cm length of the Z-pinch plasma. Separate control of plasma acceleration and compression has increased the accessible plasma parameters and has generated stable plasmas with radii of 0.3 cm, as measured with a high resolution digital holographic interferometer. Compressing the plasma with higher pinch currents has produced high magnetic fields (8.5 T) and electron temperatures (1 keV) with an electron density of 2 ×1017 cm-3, while maintaining plasma stability for many Alfvén times (approximately 50 μs). The results suggest that sheared flow stabilization can be applied to extend Z-pinch plasma parameters to high energy densities.

  16. Fluid pinch-off in superfluid and normal {sup 4}He

    SciTech Connect

    Burton, J. C.; Rutledge, J. E.; Taborek, P.

    2007-03-15

    We present frames from high-speed videos of the pinch-off of liquid {sup 4}He droplets. The temperature of the fluid droplets ranged from 1.33 K to 4.8 K, and the size of the drops was proportional to the temperature-dependent capillary length. We observed no qualitative difference between pinch-off in the normal and superfluid states. In both cases, the shape of the fluid in the final stages of pinch-off resembles a cone piercing a sphere, which is typical of other low-viscosity fluids. The evolution of the minimum neck radius r{sub min} can be characterized by power laws r{sub min}{proportional_to}{tau}{sup n}, where {tau} is the time remaining until pinch-off occurs. In the regime near pinch-off, the data from image analysis are consistent with n=2/3. The data at the beginning of the pinch process when the neck is of the order of the capillary length are also described by n=2/3, but with a different proportionality factor. There is an intermediate crossover regime characterized by n=2/5.

  17. Viscous Heating At Stagnation In Z-Pinches

    SciTech Connect

    Haines, M. G.

    2009-01-21

    The viscous heating associated with m = 0 MHD instabilities in the stagnated Z-pinch is developed further. It would appear that the larger numerical (Neumann) viscosity plus De Bar corrections in simulation codes to yield energy conservation might be another way of representing viscous heating, but in this case the viscosity is inserted to smooth shock discontinuities. However the viscous heating per unit volume appears to be independent of the coefficient of viscosity itself because the fastest growing MHD mode is itself determined by the viscous damping. Therefore it could be argued that, though the correct physics is not in the codes, the resulting heating is not sensitive to the fact that numerical viscosity instead is employed. In addition, by chance, the model of magnetic bubbles first introduced by Lovberg et al. and Riley et al., and later by Rudakov et al. to explain phenomenologically extra heating of the ions leads to the same heating rate as in Haines et al. For the stainless steel array in which T{sub i} was predicted and measured to be >200 KeV while T{sub e} = 3 KeV the ion viscous heating is dominant. However, for the low current experiment by Kroupp et al. in which the ion kinematic viscosity is much smaller than the resistive diffusivity there is resistive damping of MHD modes, and no ions viscous heating should be expected.

  18. Study of magnetic fields and current in the Z pinch at stagnation

    SciTech Connect

    Ivanov, V. V.; Anderson, A. A.; Astanovitskiy, A. L.; Nalajala, V.; Dmitriev, O.; Papp, D.

    2015-09-15

    The structure of magnetic fields in wire-array Z pinches at stagnation was studied using a Faraday rotation diagnostic at the wavelength of 266 nm. The electron plasma density and the Faraday rotation angle in plasma were calculated from images of the three-channel polarimeter. The magnetic field was reconstructed with Abel transform, and the current was estimated using a simple model. Several shots with wire-array Z pinches at 0.5–1.5 MA were analyzed. The strength of the magnetic field measured in plasma of the stagnated pinch was in the range of 1–2 MG. The magnetic field and current profile in plasma near the neck on the pinch were reconstructed, and the size of the current-carrying plasma was estimated. It was found that current flowed in the large-size trailing plasma near the dense neck. Measurements of the magnetic field near the bulge on the pinch also showed current in trailing plasma. A distribution of current in the large-size trailing plasma can prevent the formation of multi-MG fields in the Z pinch.

  19. Nonlinear dynamo mode dynamics in reversed field pinches

    NASA Astrophysics Data System (ADS)

    Fitzpatrick, Richard; Yu, Edmund P.

    2000-09-01

    The nonlinear dynamics of a typical dynamo mode in a reversed field pinch, under the action of the braking torque due to eddy currents excited in a resistive vacuum vessel and the locking torque due to a resonant error-field, is investigated. A simple set of phase evolution equations for the mode is derived: these equations represent an important extension of the well-known equations of Zohm et al. [Europhys. Lett. 11, 745 (1990)] which incorporate a self-consistent calculation of the radial extent of the region of the plasma which corotates with the mode; the width of this region being determined by plasma viscosity. Using these newly developed equations, a comprehensive theory of the influence of a resistive vacuum vessel on error-field locking and unlocking thresholds is developed. Under certain circumstances, a resistive vacuum vessel is found to strongly catalyze locked mode formation. Hopefully, the results obtained in this paper will allow experimentalists to achieve a full understanding of why the so-called "slinky mode" locks in some reversed field pinch devices, but not in others. The locking of the slinky mode is currently an issue of outstanding importance in reversed field pinch research.

  20. Nonlinear tearing mode interactions and mode locking in reversed field pinches

    SciTech Connect

    Hegna, C.C.

    1996-06-01

    The nonlinear interaction of a set of tearing instabilities and plasma flow is studied in a cylindrical plasma. An analytic theory of mode locking is developed which includes the effects of the localized electromagnetic torques, plasma inertia and cross-field viscosity. The calculation is specialized for the case of mode locking on the Madison Symmetric Torus (MST) reversed field pinch. In MST plasmas, a set of m = 1 tearing instabilities become phase locked and form a toroidally localized, rotating magnetic disturbance. An evolution equation for the phase velocity of this magnetic disturbance is derived which accounts for two types of electromagnetic torques. The external torques describe the interaction of the tearing modes with static magnetic perturbations located outside the plasma region. The interior torques describe the nonlinear interaction of three tearing modes which satisfy a wave number resonance condition. For conditions typical of MST, the internal torques dominate the external torques, which suggest the nonlinear interaction of tearing instabilities play a prominent role in the momentum degradation and mode locking.

  1. Shear & Compression Plasma Viscosity In Spherical ICF

    NASA Astrophysics Data System (ADS)

    Morse, Richard

    2003-10-01

    In (1) the exceptional viscosity of DT plasmas (Braginskii) was estimated to reduce by orders of magnitude growth rates of the most threatening m=0 modes in liner implosions of cylindrical Z-pinch plasmas that reach a thermonuclear T=10keV. Here in spherical B=0 implosions shear viscosity is estimated, by numerical(2)(implicit in t) & analytic(Chandrasekhar) methods, to reduce similarly the growth of R-T modes in DT plasmas reaching 10keV, where μ ˜5.E4 poise, or higher T. Surface plasma interactions with the confining pusher shell(3) & Knudsen(large mfp) limitation of the viscous effects are discussed. Compression viscosity(Zel'dovich) adds noticeably to irreversible heating(reduced to quadratures) in such systems, esp. with final T>10keV &/or implosion velocities >10E7cm/s. Here double implosions, as suggested in (4), can increase significantly entropy production prior to final implosion &, consequently, heating efficiency. (1)Bull. APS 44-7 Nov99 BP189 (2)McCrory et. al. Nuc.Sci.. 64,163(77) & references (3)Montierth et al., PFB 4(4) Ap92 & references (4)Two Stage Heating Of Theta Pinches, Freidberg & Morse, Proc. '71 Garching Conf. On High β Plasmas

  2. What can asymmetry tell us? Investigation of asymmetric versus symmetric pinch and swell structures in nature and simulation

    NASA Astrophysics Data System (ADS)

    Gardner, Robyn; Piazolo, Sandra; Daczko, Nathan

    2015-04-01

    Pinch and swell structures occur from microscopic to landscape scales where a more competent layer in a weaker matrix is deformed by pure shear, often in rifting environments. The Anita Shear Zone (ASZ) in Fiordland, New Zealand has an example of landscape scale (1 km width) asymmetric pinch and swell structures developed in ultramafic rocks. Field work suggests that the asymmetry is a result of variations in the surrounding 'matrix' flow properties as the ultramafic band is surrounded to the east by an orthogneiss (Milford Orthogneiss) and to the west by a paragneiss (Thurso Paragneiss). In addition, there is a narrow and a much wider shear zone between the ultramafics and the orthogneiss and paragneiss, respectively. Detailed EBSD analysis of samples from a traverse across the pinch and swell structure indicate the ultramafics in the shear zone on the orthogneiss side have larger grain size than the ultramafics in the shear zone on the paragneiss side. Ultramafic samples from the highly strained paragneiss and orthogneiss shear zones show dislocation creep behaviour, and, on the paragneiss side, also significant deformation by grain boundary sliding. To test if asymmetry of pinch and swell structures can be used to derive the rheological properties of not only the pinch and swell lithologies, but also of the matrix, numerical simulations were performed. Numerical modelling of pure shear (extension) was undertaken with (I) initially three layers and then (II) five layers by adding soft high strain zones on both sides of the rheological hard layer. The matrix was given first symmetric, then asymmetric viscosity. Matrix viscosity was found to impact the formation of pinch and swell structures with the weaker layer causing increased tortuosity of the competent layer edge due to increased local differential stress. Results highlight that local, rheologically soft layers and the relative viscosity of matrix both impact significantly the shape and symmetry of developing

  3. Putting the pinch on reactors

    SciTech Connect

    Glavic, P.; Kravanja, Z.; Homsak, M. )

    1990-06-01

    Pinch technology has proven to be a powerful tool for designing new processes and retrofitting old ones. But, until recently, it was thought to pertain only to heat exchanger networks, separators and power devices (such as heat engines and heat pumps). Regarded as process background, reactors have been left out of heat integrations. Their structure, however, can be changed and, within limits, their parameters modified to better exploit energy. In a pinch-designed plant, heat is transferred between the hot and cold process streams so efficiently that the plant's utility requirements (heat sources and sinks) are minimal. The design procedure is discussed. It involves two steps: finding a nearly optimal process structure by means of an analysis of process-temperature-vs.- enthalpy diagrams, and then optimizing the structure by means of grid diagrams or a computerized procedure.

  4. Eigenvalue pinching on spinc manifolds

    NASA Astrophysics Data System (ADS)

    Roos, Saskia

    2017-02-01

    We derive various pinching results for small Dirac eigenvalues using the classification of spinc and spin manifolds admitting nontrivial Killing spinors. For this, we introduce a notion of convergence for spinc manifolds which involves a general study on convergence of Riemannian manifolds with a principal S1-bundle. We also analyze the relation between the regularity of the Riemannian metric and the regularity of the curvature of the associated principal S1-bundle on spinc manifolds with Killing spinors.

  5. Evaluation of Particle Pinch and Diffusion Coefficients in the Edge Pedestal of DIII-D H-mode Discharges

    NASA Astrophysics Data System (ADS)

    Stacey, W. M.; Groebner, R. J.

    2009-11-01

    Momentum balance requires that the radial particle flux satisfy a pinch-diffusion relationship. The pinch can be evaluated in terms of measurable quantities (rotation velocities, Er, etc.) by the use of momentum and particle balance [1,2], the radial particle flux can be determined by momentum balance, and then the diffusion coefficient can be evaluated from the pinch diffusion relation using the measured density gradient. Applications to several DIII-D H-mode plasmas are presented. 6pt [1] W.M. Stacey, Contr. Plasma Phys. 48, 94 (2008). [2] W.M. Stacey and R.J. Groebner, Phys. Plasmas 15, 012503 (2008).

  6. Z-Pinch Fusion for Energy Applications

    SciTech Connect

    SPIELMAN,RICK B.

    2000-01-01

    Z pinches, the oldest fusion concept, have recently been revisited in light of significant advances in the fields of plasma physics and pulsed power engineering. The possibility exists for z-pinch fusion to play a role in commercial energy applications. We report on work to develop z-pinch fusion concepts, the result of an extensive literature search, and the output for a congressionally-mandated workshop on fusion energy held in Snowmass, Co July 11-23,1999.

  7. 2D Kinetic Particle in Cell Simulations of a Shear-Flow Stabilized Z-Pinch

    NASA Astrophysics Data System (ADS)

    Tummel, Kurt; Higginson, Drew; Schmidt, Andrea; Link, Anthony; McLean, Harry; Shumlak, Uri; Nelson, Brian; Golingo, Raymond; Claveau, Elliot; Lawrence Livermore National Lab Team; University of Washington Team

    2016-10-01

    The Z-pinch is a relatively simple and attractive potential fusion reactor design, but attempts to develop such a reactor have consistently struggled to overcome Z-pinch instabilities. The ``sausage'' and ``kink'' modes are among the most robust and prevalent Z-pinch instabilities, but theory and simulations suggest that axial flow-shear, dvz / dr ≠ 0 , can suppress these modes. Experiments have confirmed that Z-pinch plasmas with embedded axial flow-shear display a significantly enhanced resilience to the sausage and kink modes at a demonstration current of 50kAmps. A new experiment is under way to test the concept at higher current, and efforts to model these plasmas are being expanded. The performance and stability of these devices will depend on features like the plasma viscosity, anomalous resistivity, and finite Larmor radius effects, which are most accurately characterized in kinetic models. To predict these features, kinetic simulations using the particle in cell code LSP are now in development, and initial benchmarking and 2D stability analyses of the sausage mode are presented here. These results represent the first kinetic modeling of the flow-shear stabilized Z-pinch. This work is funded by the USDOE/ARPAe Alpha Program. Prepared by LLNL under Contract DE-AC52-07NA27344.

  8. Nested X Pinches on the COBRA Generator

    SciTech Connect

    Shelkovenko, T. A.; Pikuz, S. A.; McBride, R. D.; Knapp, P. F.; Wilhelm, H.; Hammer, D. A.; Sinars, D. B.

    2009-01-21

    Recent results of X pinch studies on the COBRA generator at Cornell University (peak current up to 1.2 MA and rise time of 100 ns) are presented. Using an initial configuration of wires before their twisting, similar to nested cylindrical wire arrays enables the assembly of a symmetric configuration at the X pinch crossing region. It also enables an investigation of multilayered X pinches. X pinches with different configurations, including with different materials in the inner and outer wire layers, were tested.

  9. Analysis of Resistive Wall Modes in RFP Plasmas with Rotation and Dissipative Effects

    NASA Astrophysics Data System (ADS)

    Guo, S. C.; Freidberg, J. P.; Nachtrieb, R.

    1998-11-01

    The stability of the non-resonant external kink modes under the resistive wall boundary condition in an RFP is analyzed. This topic is especially relevant to the future long pulse discharges. With respect to previous work(R.Nachtrieb, J.P.Freidberg and R.Betti, Reversed Field Pinch Workshop, Madison, WI October 14-16, 1996), the parallel viscosity (Braginskii's stress tensor) effects have been added into the eigenmode equation. Therefore, both the ion sound wave damping and the viscosity effects together with the plasma rotation are taken into account in the analysis. The influence of the equilibrium parameters on the mode instability is carefully studied by employing the conventional α-Θo equilibrium models. It is found that the behaviours of the RWM is rather sensitive to the reversal parameter F of RFPs. In the low β (or zero β) plasma region, there is a stability window in the wall-plasma distance b/a due to the plasma rotation and viscous dissipative effects. For the typical RFP operating parameters, the required rotation velocity to stabilize the modes is in the range of the ion sound speed or even higher. The effects of the viscosity on the instability of the modes are investigated.

  10. High energy density Z-pinch plasmas using flow stabilization

    SciTech Connect

    Shumlak, U. Golingo, R. P. Nelson, B. A. Bowers, C. A. Doty, S. A. Forbes, E. G. Hughes, M. C. Kim, B. Knecht, S. D. Lambert, K. K. Lowrie, W. Ross, M. P. Weed, J. R.

    2014-12-15

    The ZaP Flow Z-Pinch research project[1] at the University of Washington investigates the effect of sheared flows on MHD instabilities. Axially flowing Z-pinch plasmas are produced that are 100 cm long with a 1 cm radius. The plasma remains quiescent for many radial Alfvén times and axial flow times. The quiescent periods are characterized by low magnetic mode activity measured at several locations along the plasma column and by stationary visible plasma emission. Plasma evolution is modeled with high-resolution simulation codes – Mach2, WARPX, NIMROD, and HiFi. Plasma flow profiles are experimentally measured with a multi-chord ion Doppler spectrometer. A sheared flow profile is observed to be coincident with the quiescent period, and is consistent with classical plasma viscosity. Equilibrium is determined by diagnostic measurements: interferometry for density; spectroscopy for ion temperature, plasma flow, and density[2]; Thomson scattering for electron temperature; Zeeman splitting for internal magnetic field measurements[3]; and fast framing photography for global structure. Wall stabilization has been investigated computationally and experimentally by removing 70% of the surrounding conducting wall to demonstrate no change in stability behavior.[4] Experimental evidence suggests that the plasma lifetime is only limited by plasma supply and current waveform. The flow Z-pinch concept provides an approach to achieve high energy density plasmas,[5] which are large, easy to diagnose, and persist for extended durations. A new experiment, ZaP-HD, has been built to investigate this approach by separating the flow Z-pinch formation from the radial compression using a triaxial-electrode configuration. This innovation allows more detailed investigations of the sheared flow stabilizing effect, and it allows compression to much higher densities than previously achieved on ZaP by reducing the linear density and increasing the pinch current. Experimental results and

  11. Pinch-off dynamics and dripping-onto-substrate (DoS) rheometry of complex fluids.

    PubMed

    Dinic, Jelena; Jimenez, Leidy Nallely; Sharma, Vivek

    2017-01-31

    Liquid transfer and drop formation/deposition processes involve complex free-surface flows including the formation of columnar necks that undergo spontaneous capillary-driven instability, thinning and pinch-off. For simple (Newtonian and inelastic) fluids, a complex interplay of capillary, inertial and viscous stresses determines the nonlinear dynamics underlying finite-time singularity as well as self-similar capillary thinning and pinch-off dynamics. In rheologically complex fluids, extra elastic stresses as well as non-Newtonian shear and extensional viscosities dramatically alter the nonlinear dynamics. Stream-wise velocity gradients that arise within the thinning columnar neck create an extensional flow field, and many complex fluids exhibit a much larger resistance to elongational flows than Newtonian fluids with similar shear viscosity. Characterization of pinch-off dynamics and the response to both shear and extensional flows that influence drop formation/deposition in microfluidic and printing applications requires bespoke instrumentation not available, or easily replicated, in most laboratories. Here we show that dripping-onto-substrate (DoS) rheometry protocols that involve visualization and analysis of capillary-driven thinning and pinch-off dynamics of a columnar neck formed between a nozzle and a sessile drop can be used for measuring shear viscosity, power law index, extensional viscosity, relaxation time and the most relevant processing timescale for printing. We showcase the versatility of DoS rheometry by characterizing and contrasting the pinch-off dynamics of a wide spectrum of simple and complex fluids: water, printing inks, semi-dilute polymer solutions, yield stress fluids, food materials and cosmetics. We show that DoS rheometry enables characterization of low viscosity printing inks and polymer solutions that are beyond the measurable range of commercially-available capillary break-up extensional rheometer (CaBER). We show that for high

  12. Pinch Experiments in a Table Top Generator

    SciTech Connect

    Pavez, Cristian; Moreno, Jose; Soto, Leopoldo; Tarifeno, Ariel

    2009-01-21

    The design and construction of a table top multipurpose capacitor bank of hundred of Joules and hundred of kiloAmperes conceived to be used in small scale Z-pinch experiments is reported. A recent result on a Z-pinch gas embedded discharge using hollow conical electrodes done in a similar table top generator is also presented.

  13. The high density Z-pinch

    SciTech Connect

    McCall, G.H.

    1988-01-01

    During the past few years techniques have been developed for producing pinches in solid deuterium. The conditions which exist in these plasmas are quiet different from those produced earlier. The pinch is formed from a fiber of solid deuterium rather than from a low density gas, and the current is driven by a low impedance, high voltage pulse generator. Because of the high initial density, it is not necessary to compress the pinch to reach thermonuclear conditions, and the confinement time required for energy production is much shorter than for a gas. The experimental results, which have been verified by experiments performed at higher current were quite surprising and encouraging. The pinch appeared to be stable for a time much longer than the Alfven radial transit time. In this paper, however, I argue that the pinch is not strictly stable, but it does not appear to disassemble in a catastrophic fashion. It appears that there may be a distinction between stability and confinement in the high density pinch. In the discussion below I will present the status of the high density Z-pinch experiments at laboratories around the world, and I will describe some of the calculational and experimental results. I will confine my remarks to recent work on the high density pinch. 17 refs. 10 figs.

  14. Pinch technology/process optimization

    SciTech Connect

    Not Available

    1992-12-01

    Improved process efficiency is of great importance to electric utilities and their industrial customers. It enhances company profitability, thereby fostering load retention and strategic load growth. Moreover, the technical means of achieving improved efficiency can significantly impact utility load shapes. By understanding the energy use patterns and options in an industrial facility, the utility and industrial user can work together to define mutually beneficial investment and operating decisions and to clarify how the decisions might be impacted by existing or alternative energy prices. Efforts to achieve such understanding are facilitated by using pinch technology, an innovative and highly effective methodology for systematically analyzing total industrial sites. This report documents a series of twelve industrial process optimization case studies. The studies were carried out using pinch technology. '' Each study was cosponsored by the industrial site's local electric utility. The twelve studies are follows: (1) pulp and paper, (2) refinery, (3) refinery, (4) yeast, (5) soups/sauces, (6) cellulose- acetate, (7) refinery, (8) chemicals, (9) gelatin-capsules, (10) refinery, (11) brewery, (12) cereal grains.

  15. 3D Modelling of X-pinches.

    NASA Astrophysics Data System (ADS)

    Ciardi, A.; Chittenden, J. P.; Lebedev, S. V.; Bland, S. N.; Jennings, C. A.

    2003-10-01

    X-pinch produced plasmas are an intense source of soft x-rays generated by passing a large, fast rising current through two or more thin metallic wires crossed in the shape of <93>an "X". During the current pulse, the plasma is pinched at the crossing point where a dense Z-pinch plasma column develops. Further compression produces micron sized x-ray hot spots with energy densities in excess of ˜10^24 eV cm-3. We present 3D resistive magnetohydrodynamic simulations of two- and four-wire X-pinches for a variety of wire materials. The simulations naturally follow the evolution of the X-pinch: jet-like structures on axis, formation of a Z-pinch and its subsequent rapid evolution and production of x-ray hot spots. The effects of wire material and wire number are studied with particular consideration to the relationship between the magnetic confinement and radiative cooling mechanisms, which ultimately determine the complex behaviour of the X-pinch.

  16. Anisotropic eddy viscosity models

    NASA Technical Reports Server (NTRS)

    Carati, D.; Cabot, W.

    1996-01-01

    A general discussion on the structure of the eddy viscosity tensor in anisotropic flows is presented. The systematic use of tensor symmetries and flow symmetries is shown to reduce drastically the number of independent parameters needed to describe the rank 4 eddy viscosity tensor. The possibility of using Onsager symmetries for simplifying further the eddy viscosity is discussed explicitly for the axisymmetric geometry.

  17. Pinch-off of microfluidic droplets with oscillatory velocity of inner phase flow

    PubMed Central

    Zhu, Pingan; Tang, Xin; Tian, Ye; Wang, Liqiu

    2016-01-01

    When one liquid is introduced into another immiscible one, it ultimately fragments due to hydrodynamic instability. In contrast to neck pinch-off without external actuation, the viscous two-fluid system subjected to an oscillatory flow demonstrates higher efficiency in breaking fluid threads. However, the underlying dynamics of this process is less well understood. Here we show that the neck-thinning rate is accelerated by the amplitude of oscillation. By simply evaluating the momentum transfer from external actuation, we derive a dimensionless pre-factor to quantify the accelerated pinch-off. Our data ascribes the acceleration to the non-negligible inner fluid inertia, which neutralizes the inner phase viscous stress that retards the pinch-off. Moreover, we characterize an equivalent neck-thinning behavior between an actuated system and its unactuated counterpart with decreased viscosity ratio. Finally, we demonstrate that oscillation is capable of modulating satellite droplet formation by shifting the pinch-off location. Our study would be useful for manipulating fluids at microscale by external forcing. PMID:27511300

  18. Pinch-off of microfluidic droplets with oscillatory velocity of inner phase flow

    NASA Astrophysics Data System (ADS)

    Zhu, Pingan; Tang, Xin; Tian, Ye; Wang, Liqiu

    2016-08-01

    When one liquid is introduced into another immiscible one, it ultimately fragments due to hydrodynamic instability. In contrast to neck pinch-off without external actuation, the viscous two-fluid system subjected to an oscillatory flow demonstrates higher efficiency in breaking fluid threads. However, the underlying dynamics of this process is less well understood. Here we show that the neck-thinning rate is accelerated by the amplitude of oscillation. By simply evaluating the momentum transfer from external actuation, we derive a dimensionless pre-factor to quantify the accelerated pinch-off. Our data ascribes the acceleration to the non-negligible inner fluid inertia, which neutralizes the inner phase viscous stress that retards the pinch-off. Moreover, we characterize an equivalent neck-thinning behavior between an actuated system and its unactuated counterpart with decreased viscosity ratio. Finally, we demonstrate that oscillation is capable of modulating satellite droplet formation by shifting the pinch-off location. Our study would be useful for manipulating fluids at microscale by external forcing.

  19. Reduction of viscosity in suspension of swimming bacteria.

    SciTech Connect

    Aranson, I. S.; Sokolov, A.; Chen, L.; Jin, Q.; Materials Science Division

    2009-09-29

    Measurements of the shear viscosity in suspensions of swimming Bacillus subtilis in free-standing liquid films have revealed that the viscosity can decrease by up to a factor of 7 compared to the viscosity of the same liquid without bacteria or with nonmotile bacteria. The reduction in viscosity is observed in two complementary experiments: one studying the decay of a large vortex induced by a moving probe and another measuring the viscous torque on a rotating magnetic particle immersed in the film. The viscosity depends on the concentration and swimming speed of the bacteria.

  20. Reduction of viscosity in suspension of swimming bacteria.

    SciTech Connect

    Sokolov, A.; Aranson, I. S.; Materials Science Division; Illinois Inst. of Tech.

    2009-01-01

    Measurements of the shear viscosity in suspensions of swimming Bacillus subtilis in free-standing liquid films have revealed that the viscosity can decrease by up to a factor of 7 compared to the viscosity of the same liquid without bacteria or with nonmotile bacteria. The reduction in viscosity is observed in two complementary experiments: one studying the decay of a large vortex induced by a moving probe and another measuring the viscous torque on a rotating magnetic particle immersed in the film. The viscosity depends on the concentration and swimming speed of the bacteria.

  1. Study of micro-pinches in wire-array Z pinches

    SciTech Connect

    Ivanov, V. V.; Papp, D.; Anderson, A. A.; Talbot, B. R.; Astanovitskiy, A. L.; Nalajala, V.; Dmitriev, O.; Chittenden, J. P.; Niasse, N.; Pikuz, S. A.; Shelkovenko, T. A.

    2013-11-15

    Bright and hot areas with a high plasma density and temperature are observed in all kinds of Z pinches. We studied bright radiating spots produced by micro-pinches in cylindrical and planar wire-arrays at the 1 MA Zebra pulsed power generator using an x-ray streak camera synchronized with laser diagnostics, x-ray time-gated pinhole camera, and spectroscopy. Hot spots with extremely dense and relatively hot plasma arise during the collapse of the micro-pinches. These hot spots radiate a continuum spectrum with energy >2.5 keV. Typical micro-pinches in Al wire arrays generate x-ray bursts with durations of 0.4–1 ns in the soft x-ray range and 0.1–0.4 ns in the keV range. UV two-frame shadowgraphy shows spatial correlation of hot spots with the collapse and explosion of micro-pinches. Micro-pinches typically occur at the necks of the Z pinch, but can demonstrate a variety of parameters and different dynamics. An analysis of x-ray streak images shows that micro-pinches can generate >20% of the x-ray energy in some types of wire-array Z pinches.

  2. Shape Analysis of Multi-layer Parison at the Pinch-off Process in Extrusion Blow Molding

    NASA Astrophysics Data System (ADS)

    Fukuzawa, Youhei; Tanoue, Shuichi; Touda, Masumi; Iemoto, Yoshiyuki; Kawachi, Ryuichi; Tomiyama, Hideki

    The shape of a multi-layer parison at the pinch-off process in extrusion blow molding was experimentally and quantitatively analyzed by a rapid cooling method. The multi-layers used in this study were composed of HDPE as inner and outer layers and LDPE with lower viscosity by five times than HDPE as a middle layer. The results obtained in this study are as follows 1) The land region of a mold has no effects on the parison shape at the pinch-off process. 2) The clearance between knives for pinch-off has significant influence on the parison shape. In particular the clearance from 0 mm to 0.1 mm shows remarkable effects on each layer thickness of the parison. 3) In proportion to the decrease of the clearance, the thickness ratio of the middle layer increases owing to the fluidity difference between HDPE and LDPE.

  3. Formation of a sheared flow Z pinch

    NASA Astrophysics Data System (ADS)

    Golingo, R. P.; Shumlak, U.; Nelson, B. A.

    2005-06-01

    The ZaP Flow Z-Pinch project is experimentally studying the effect of sheared flows on Z-pinch stability. It has been shown theoretically that when dVz/dr exceeds 0.1kVA the kink (m =1) mode is stabilized. [U. Shumlak and C. W. Hartman, Phys. Rev. Lett. 75, 3285 (1995).] Z pinches with an embedded axial flow are formed in ZaP with a coaxial accelerator coupled with a 1m assembly region. Long-lived, quiescent Z pinches are generated throughout the first half cycle of the current. During the initial plasma acceleration phase, the axial motion of the current sheet is consistent with snowplow models. Magnetic probes in the assembly region measure the azimuthal modes of the magnetic field. The amplitude of the m =1 mode is proportional to the radial displacement of the Z-pinch plasma current. The magnetic mode levels show a quiescent period which is over 2000 times the growth time of a static Z pinch. The axial velocity is measured along 20 chords through the plasma and deconvolved to provide a radial profile. Using data from multiple pulses, the time evolution of the velocity profile is measured during formation, throughout the quiescent period, and into the transition to instability. The evolution shows that a sheared plasma flow develops as the Z pinch forms. Throughout the quiescent period, the flow shear is greater than the theoretically required threshold for stability. As the flow shear decreases, the magnetic mode fluctuations increase. The coaxial accelerator provides plasma throughout the quiescent period and may explain the evolution of the velocity profile and the sustainment of the flow Z pinch.

  4. The physics of fast Z pinches

    SciTech Connect

    Ryutov, D.D.; Derzon, M.S.; Matzen, M.K.

    1998-07-01

    The spectacular progress made during the last few years in reaching high energy densities in fast implosions of annular current sheaths (fast Z pinches) opens new possibilities for a broad spectrum of experiments, from x-ray generation to controlled thermonuclear fusion and astrophysics. Presently Z pinches are the most intense laboratory X ray sources (1.8 MJ in 5 ns from a volume 2 mm in diameter and 2 cm tall). Powers in excess of 200 TW have been obtained. This warrants summarizes the present knowledge of physics that governs the behavior of radiating current-carrying plasma in fast Z-pinches. This survey covers essentially all aspects of the physics of fast Z pinches: initiation, instabilities of the early stage, magnetic Rayleigh-Taylor instability in the implosion phase, formation of a transient quasi-equilibrium near the stagnation point, and rebound. Considerable attention is paid to the analysis of hydrodynamic instabilities governing the implosion symmetry. Possible ways of mitigating these instabilities are discussed. Non-magnetohydrodynamic effects (anomalous resistivity, generation of particle beams, etc.) are summarized. Various applications of fast Z pinches are briefly described. Scaling laws governing development of more powerful Z pinches are presented. The survey contains 52 figures and nearly 300 references.

  5. Symmetric multilayer megampere X-pinch

    SciTech Connect

    Shelkovenko, T. A.; Pikuz, S. A.; McBride, R. D.; Knapp, P. F.; Wilhelm, G.; Sinars, D. B.; Hammer, D. A.; Orlov, N. Yu.

    2010-01-15

    Raising the power of X-ray emission from an X-pinch by increasing the pinch current to the megampere level requires the corresponding increase in the initial linear mass of the load. This can be achieved by increasing either the number of wires or their diameter. In both cases, special measures should be undertaken to prevent the formation of a complicated configuration with an uncontrolled spatial structure in the region of wire crossing, because such a structure breaks the symmetry of the neck formed in the crossing region, destabilizes plasma formation, and degrades X-ray generation. To improve the symmetry of the wire crossing region, X-pinch configurations with a regular multilayer arrangement of wires in this region were proposed and implemented. The results of experiments with various symmetric X-pinch configurations on the COBRA facility at currents of {approx}1MA are presented. It is shown that an X-pinch with a symmetric crossing region consisting of several layers of wires made of different materials can be successfully used in megampere facilities. The most efficient combinations of wires in symmetric multilayer X-pinches are found in which only one hot spot forms and that are characterized by a high and stable soft X-ray yield.

  6. The Physics of Fast Z Pinches

    SciTech Connect

    RYUTOV,D.D.; DERZON,MARK S.; MATZEN,M. KEITH

    1999-10-25

    The spectacular progress made during the last few years in reaching high energy densities in fast implosions of annular current sheaths (fast Z pinches) opens new possibilities for a broad spectrum of experiments, from x-ray generation to controlled thermonuclear fusion and astrophysics. Presently Z pinches are the most intense laboratory X ray sources (1.8 MJ in 5 ns from a volume 2 mm in diameter and 2 cm tall). Powers in excess of 200 TW have been obtained. This warrants summarizing the present knowledge of physics that governs the behavior of radiating current-carrying plasma in fast Z pinches. This survey covers essentially all aspects of the physics of fast Z pinches: initiation, instabilities of the early stage, magnetic Rayleigh-Taylor instability in the implosion phase, formation of a transient quasi-equilibrium near the stagnation point, and rebound. Considerable attention is paid to the analysis of hydrodynamic instabilities governing the implosion symmetry. Possible ways of mitigating these instabilities are discussed. Non-magnetohydrodynamic effects (anomalous resistivity, generation of particle beams, etc.) are summarized. Various applications of fast Z pinches are briefly described. Scaling laws governing development of more powerful Z pinches are presented. The survey contains 36 figures and more than 300 references.

  7. Asynchonous Binaries, Energy Dissipation and Turbulent Viscosity

    NASA Astrophysics Data System (ADS)

    Koenigsberger, G.; Brott, I.; Moreno, E.

    2015-07-01

    Stars in binary systems are generally modeled under the assumption that they are in an equilibrium configuration and, in particular, that the stellar rotation angular velocity equals the orbital angular velocity. However, asynchronous rotation is more common than generally recognized. All eccentric systems undergo asynchronous rotation and the angular velocity of rotation of many stars in circular orbits differs from that of the orbital angular velocity. Combined with the external gravitational potential, this asynchronous rotation causes shearing motions in the stellar layers and, given that the stellar material is not inviscid, kinetic energy is dissipated into heat. In 1968, Zdeněk Kopal addressed the question of whether the tidal shear energy dissipation rates, Ė, in asynchronous binaries can lead to an internal stellar structure that differs from that in an analogous single star. His calculation, based on the assumption that the viscosity is purely molecular, led him to conclude that Ė is insignificant and therefore has no effect on the internal stellar structure. However, Kopal also pointed out the important caveat that if turbulent viscosity prevailed, then larger values of Ė would obtain. We have revisited the question of the magnitude of Ė using the TIDES code (Moreno 2011) and examined its dependence on viscosity for several layers of a ZAMS 30 M⊙ star with a 20 M⊙ companion in a 6-day eccentric orbit. We find that conditions for turbulent viscosity are favored when the star expands after leaving the main sequence. For example, when the 30 M⊙ star is 5 Myr old and rotating near its corrotation speed, turbulent viscosity might be expected to appear in all layers at distances greater than 60% of the maximum stellar radius. As a consequence, tidal shear energy dissipation may constitute a non-negligible effect in a large number of close binary systems, with possibly interesting consequences for their internal structure and evolution.

  8. Star pinch scalable EUV source

    NASA Astrophysics Data System (ADS)

    McGeoch, Malcolm W.; Pike, Charles T.

    2003-06-01

    A new direct discharge source of 13.5nm radiation addresses the heat load problem by creating the plasma remote from all surfaces. The plasma is initially formed at the intersection of many pulsed xenon beamlets. Further heating is then applied via a high current pulse to induce efficient radiation from Xe10+ ions. The plasma is compact, with a single pulse FWHM diameter of 0.7mm and length of 3mm. It is positionally stable, as illustrated by re-imaging onto a fluorescent screen sensitive to EUV and time-integrating over 250 pulses. In this mode the averaged FWHM is 0.9mm. The conversion efficiency from stored electrical energy to radiation within 2π sterad and 2% bandwidth at 13.5nm is currently 0.55%, using xenon. Power is delivered to the plasma by a solid state-switched modulator operated at a stored energy of 25J of which 10J is dissipated in the plasma plus circuit, and 15J is recovered. The EUV output in 2% bandwidth at 13.5nm is 9mJ/sterad. Repetition rate scaling of the star pinch EUV source to 1kHz there is negligible electrode erosion at 106 pulses. This is possible because the cathode for the main heating discharge is distributed into 24-fold parallel hollow cathodes, with a combined operational surface aera of approximately 20cm2. The anode is similarly distributed. The walls facing the plasma are 22mm distant from it and when scaled to 6kHz will see a heat load of less than 1kWcm-2. The cathode electrode is then expected to receive a heat load of less than 500W cm-2. The plasma is expected to clear between pulses and be reproducible at frequencies up to at least 10kHz, at which rate the usable EUV power available at a second focus, assuming colleciton in 2sterad, is predicted to be more than 80W. The star pinch has properties that favor long life and appears to scale to the 50-100W powers needed for high throughput lithography.

  9. Optical viscosity sensor

    NASA Astrophysics Data System (ADS)

    Chang, Cheng-Ling; Peyroux, Juliette; Perez, Alex; Tsui, Chi-Leung; Wang, Wei-Chih

    2009-03-01

    Viscosity measurement by bend loss of fiber is presented. The sensing principle makes use of the damping characteristic of a vibrating optical fiber probe with fix-free end configuration. By measuring the displacement of the fiber probe, the viscosity can be determined by matching the probe's displacement with the displacement built in the database obtained by either experimental method or Finite element calculation. Experimental results are presented by measuring the sucrose and glycerol solutions of different concentrations with a viscosity varying from 1 to 15 cP. Stokes' flow assumption is utilized to attenuate the mass density effect and simplify the viscosity measurement.

  10. Numerical estimates for the bulk viscosity of ideal gases

    NASA Astrophysics Data System (ADS)

    Cramer, M. S.

    2012-06-01

    We estimate the bulk viscosity of a selection of well known ideal gases. A relatively simple formula is combined with published values of rotational and vibrational relaxation times. It is shown that the bulk viscosity can take on a wide variety of numerical values and variations with temperature. Several fluids, including common diatomic gases, are seen to have bulk viscosities which are hundreds or thousands of times larger than their shear viscosities. We have also provided new estimates for the bulk viscosity of water vapor in the range 380-1000 K. We conjecture that the variation of bulk viscosity with temperature will have a local maximum for most fluids. The Lambert-Salter correlation is used to argue that the vibrational contribution to the bulk viscosities of a sequence of fluids having a similar number of hydrogen atoms at a fixed temperature will increase with the characteristic temperature of the lowest vibrational mode.

  11. Optical diagnostics on dense Z-pinch plasmas

    SciTech Connect

    Riley, R.A. Jr.; Lovberg, R.H.; Shlachter, J.S.; Scudder, D.W.

    1992-05-01

    A novel ``point-diffraction`` interferometer has been implemented on the Los Alamos Solid Fiber Z-Pinch experiment. The laser beam is split into two legs after passing through the plasma. The reference leg is filtered with a pin-hole aperture and recombined with the other leg to form an interferogram. This allows compact mounting of the optics and relative ease of alignment. The Z-Pinch experiment employs a pulsed-power generator that delivers up to 700 KA with a 100ns rise-time through a fiber of deuterium or deuterated polyethylene (CD{sub s}) that is 5-cm long and initially solid with radius r{approx}15{mu}m. The interferometer, using a {triangle}t{approx}200ps pulse from a Nd:YAG laser frequency doubled to {lambda}=532nm, measures the electron line density and, assuming azimuthal symmetry, the density as a function of radial and axial position. Calculations predict Faraday rotations of order {pi}/2 for plasma and current densities that this experiment was designed to produce. The resulting periodic loss of fringes would provide the current density distribution.

  12. Roles of viscosity, polarity, and hydrogen-bonding ability of a pyrrolidinium ionic liquid and its binary mixtures in the photophysics and rotational dynamics of the potent excited-state intramolecular proton-transfer probe 2,2'-bipyridine-3,3'-diol.

    PubMed

    Mandal, Sarthak; Ghosh, Surajit; Banerjee, Chiranjib; Kuchlyan, Jagannath; Sarkar, Nilmoni

    2013-06-06

    The room-temperature ionic liquid [C3mpyr][Tf2N] and its binary mixtures with methanol and acetonitrile provide microenvironments of varying viscosity, polarity, and hydrogen-bonding ability. The present work highlights their effects on the photophysics and rotational dynamics of a potent excited-state intramolecular double-proton-transfer (ESIDPT) probe, 2,2'-bipyridine-3,3'-diol [BP(OH)2]. The rotational diffusion of the proton-transferred diketo (DK) tautomer in [C3mpyr][Tf2N] ionic liquid was analyzed for the first time from the experimentally obtained temperature-dependent fluorescence anisotropy data using Stokes-Einstein-Debye (SED) hydrodynamic theory and Gierer-Wirtz quasihydrodynamic theory (GW-QHT). It was found that the rotation of the DK tautomer in neat ionic liquid is governed solely by the viscosity of the medium, as the experimentally observed boundary-condition parameter, Cobs, was very close to the GW boundary-condition parameter (CGW). On the basis of photophysical studies of BP(OH)2 in IL-cosolvent binary mixtures, we suggest that methanol molecules form hydrogen bonds with the cationic counterpart of the DK tautomers, as evidenced by the greater extent of the decrease in the fluorescence lifetime of BP(OH)2 upon addition of methanol compared to acetonitrile. It is also possible for the methanol molecules to form hydrogen bonds with the constituents of the RTIL, which is supported by the lesser extent of the decrease in the viscosity of the medium upon addition of methanol, leading to a less effective decrease in the rotational relaxation time compared to that observed upon acetonitrile addition.

  13. Viscosity and Solvation

    ERIC Educational Resources Information Center

    Robertson, C. T.

    1973-01-01

    Discusses theories underlying the phenomena of solution viscosities, involving the Jones and Dole equation, B-coefficient determination, and flickering cluster model. Indicates that viscosity measurements provide a basis for the study of the structural effects of ions in aqueous solutions and are applicable in teaching high school chemistry. (CC)

  14. Viscosity measuring using microcantilevers

    DOEpatents

    Oden, Patrick Ian

    2001-01-01

    A method for the measurement of the viscosity of a fluid uses a micromachined cantilever mounted on a moveable base. As the base is rastered while in contact with the fluid, the deflection of the cantilever is measured and the viscosity determined by comparison with standards.

  15. Viscosity and Solvation

    ERIC Educational Resources Information Center

    Robertson, C. T.

    1973-01-01

    Discusses theories underlying the phenomena of solution viscosities, involving the Jones and Dole equation, B-coefficient determination, and flickering cluster model. Indicates that viscosity measurements provide a basis for the study of the structural effects of ions in aqueous solutions and are applicable in teaching high school chemistry. (CC)

  16. Apparatus and method for measuring viscosity

    DOEpatents

    Murphy, R.J. Jr.

    1986-02-25

    The present invention is directed to an apparatus and method for measuring the viscosity of a fluid. This apparatus and method is particularly useful for the measurement of the viscosity of a liquid in a harsh environment characterized by high temperature and the presence of corrosive or deleterious gases and vapors which adversely affect conventional ball or roller bearings. The apparatus and method of the present invention employ one or more flexural or torsional bearings to suspend a bob capable of limited angular motion within a rotatable sleeve suspended from a stationary frame. 7 figs.

  17. Apparatus and method for measuring viscosity

    DOEpatents

    Murphy, Jr., Robert J.

    1986-01-01

    The present invention is directed to an apparatus and method for measuring the viscosity of a fluid. This apparatus and method is particularly useful for the measurement of the viscosity of a liquid in a harsh environment characterized by high temperature and the presence of corrosive or deleterious gases and vapors which adversely affect conventional ball or roller bearings. The apparatus and method of the present invention employ one or more flexural or torsional bearings to suspend a bob capable of limited angular motion within a rotatable sleeve suspended from a stationary frame.

  18. Study of the internal structure, instabilities, and magnetic fields in the dense Z-pinch

    SciTech Connect

    Ivanov, Vladimir V.

    2016-08-17

    plasma will be studied to estimate its contribution to the Doppler broadening of x-ray lines. Development of “necks” and “hot spots” will be studied with high-resolution UV diagnostics, an x-ray streak camera, and x-ray spectroscopy. Laser initiation of hot spots in Z pinches will be tested. A Faraday rotation diagnostic at 266 nm will be applied to 1-10 MG magnetic fields. For magnetic fields B>20 MG, suggested in micropinches, Cotton-Mouton and cutoff diagnostics will be applied. A picosecond optical Kerr shutter will be tested to increase a sensitivity of UV methods for application at multi-MA Z pinches. The proposal is based on the experimental capability of NTF. The Zebra generator produces 1-1.7 MA Z-pinches with electron plasma density of 1020-1021cm-3, electron temperature of 0.5-1 keV, and magnetic fields >10 MG. The Leopard laser was upgraded to energy of 90-J at 0.8 ns. This regime will be used for laser initiation of hot spots. A further upgrade to energy of 250-J is suggested for laser-Z-pinch interaction. A picosecond regime will be used for optical gating. A 10-TW Tomcat laser at NTF is available for the high energy UV laser probing of the Z-pinch. Two graduate students will develop new optical and x-ray diagnostics, carry out experiments, and process experimental data. Other students will be involved in the design and fabrication of loads, supporting regular optical and x-ray diagnostics, and data processing. The new plasma diagnostics may be applied to HEDP experiments at NTF and other multi-MA generators. The feasibility of the research plan is based on the experience of the scientific team in Z-pinch plasma physics, laser physics, development of new plasma diagnostics, and the experimental capability of NTF. The experimental group of Dr. V. V. Ivanov (UNR) collaborates with a group for Z pinch MHD modeling of Dr. J. P. Chittenden (Imperial College, London), and theoretical group of Dr. D. D. Ryutov (LLNL). The

  19. Pinch technique: Theory and applications

    NASA Astrophysics Data System (ADS)

    Binosi, Daniele; Papavassiliou, Joannis

    2009-08-01

    We review the theoretical foundations and the most important physical applications of the Pinch Technique (PT). This general method allows the construction of off-shell Green’s functions in non-Abelian gauge theories that are independent of the gauge-fixing parameter and satisfy ghost-free Ward identities. We first present the diagrammatic formulation of the technique in QCD, deriving, at one loop, the gauge independent gluon self-energy, quark-gluon vertex, and three-gluon vertex, together with their Abelian Ward identities. The generalization of the PT to theories with spontaneous symmetry breaking is carried out in detail, and the profound connection with the optical theorem and the dispersion relations are explained within the electroweak sector of the Standard Model. The equivalence between the PT and the Feynman gauge of the Background Field Method (BFM) is elaborated, and the crucial differences between the two methods are critically scrutinized. A variety of field theoretic techniques needed for the generalization of the PT to all orders are introduced, with particular emphasis on the Batalin-Vilkovisky quantization method and the general formalism of algebraic renormalization. The main conceptual and technical issues related to the extension of the technique beyond one loop are described, using the two-loop construction as a concrete example. Then the all-order generalization is thoroughly examined, making extensive use of the field theoretic machinery previously introduced; of central importance in this analysis is the demonstration that the PT-BFM correspondence persists to all orders in perturbation theory. The extension of the PT to the non-perturbative domain of the QCD Schwinger-Dyson equations is presented systematically, and the main advantages of the resulting self-consistent truncation scheme are discussed. A plethora of physical applications relying on the PT are finally reviewed, with special emphasis on the definition of gauge

  20. Fusion in a staged Z-pinch

    NASA Astrophysics Data System (ADS)

    Wessel, F. J.; Rahman, H. U.; Ney, P.; Valenzuela, J.; Beg, F.; McKee, E.; Darling, T.

    2016-03-01

    This paper is dedicated to Norman Rostoker, our (FJW and HUR) mentor and long-term collaborator, who will always be remembered for the incredible inspiration that he has provided us. Norman's illustrious career dealt with a broad range of fundamental-physics problems and we were fortunate to have worked with him on many important topics: intense-charged-particle beams, field-reversed configurations, and Z-pinches. Rostoker 's group at the University of CA, Irvine was well known for having implemented many refinements to the Z-pinch, that make it more stable, scalable, and efficient, including the development of: the gas-puff Z-pinch [1], which provides for the use of an expanded range of pinch-load materials; the gas-mixture Z-pinch [2], which enhances the pinch stability and increases its radiation efficiency; e-beam pre-ionization [3], which enhances the uniformity of the initial-breakdown process in a gas pinch; magnetic-flux-compression [4, 5], which allows for the amplification of an axial-magnetic field Bz; the Z-θ pinch [6], which predicts fusion in a pinch-on-fiber configuration; the Staged Z-pinch (SZP) [7], which allows for the amplification of the pinch self-magnetic field, Bθ , in addition to a Bz, and leads to a stable implosion and high-gain fusion [8, 9, 10]. This paper describes the physical basis for a magneto-inertial compression in a liner-on-target SZP [11]. Initially a high-atomic-number liner implodes under the action of the J →×B → , Lorentz Force. As the implosion becomes super Alfvénic, magnetosonic waves form, transporting current and magnetic field through the liner toward the interface of the low-atomic-number target. The target implosion remains subsonic with its surface bounded by a stable-shock front. Shock waves that pass into the target provide a source of target plasma pre-heat. At peak compression the assembly is compressed by liner inertia, with flux compression producing an intense-magnetic field near the target

  1. Pyrrolic molecular rotors acting as viscosity sensors with high fluorescence contrast.

    PubMed

    Lee, Seung-Chul; Heo, Jeongyun; Ryu, Jong-Wan; Lee, Chang-Lyoul; Kim, Sehoon; Tae, Joon-Sung; Rhee, Byung-Ohk; Kim, Sang-Wook; Kwon, O-Pil

    2016-11-17

    New pyrrolic viscosity sensors exhibit one order of magnitude higher fluorescence contrast compared to that of the conventional phenolic analogues due to the viscosity-sensitive rotation of the asymmetric pyrrole group and successfully demonstrate mapping of intracellular viscosity by fluorescence lifetime imaging microscopy.

  2. Z-pinch equilibrium and instability analysis with digital holographic interferometry

    NASA Astrophysics Data System (ADS)

    Ross, M. P.; Shumlak, U.; Nelson, B. A.; Golingo, R. P.; Hughes, M. C.; Claveau, E. L.; Weed, J. R.; Forbes, E. G.; Doty, S. A.; Kim, B.

    2015-11-01

    The ZaP-HD Flow Z-Pinch project generates flow shear stabilized Z-pinches, providing a platform to explore how such plasmas could scale to HEDP and fusion reactor conditions. To scale up the plasma's density and temperature, it must be compressed to a smaller size making measurements more difficult. Digital holographic interferometry (DHI) employing a pulsed Nd:YAG laser and consumer DSLR camera can spatially resolve the plasma's electron density. The Fresnel reconstruction method allows expedient numerical data reconstruction. Obtaining electron density radial profiles relies on applying an Abel inversion to convert measured line-integrated density, and the inversion process provides an independent measure of plasma symmetry. Entire Z-pinch equilibria (n, P, T, and B profiles) can be computed by applying physical models to the density data. Tracking the time evolution of pressure and density can reveal the presence of non-adiabatic heating mechanisms. Imaging the size scales of instabilities enables relative measures of viscosity at different positions and times. Error estimation of measured density profiles is presented along with observed asymmetric instabilities. This work is supported by grants from the U.S. Department of Energy and the U.S. National Nuclear Security Administration.

  3. Development of a plasma pinch photocathode

    NASA Astrophysics Data System (ADS)

    Asmus, John F.

    The need in advanced Linacs is for a high-performance (emittance, current, and life) cathode that will not poison in the only moderately good vacuums of such systems. Our approach embodies the durability of an unsensitized metal photocathode that is illuminated by a high-Z, high-density plasma pinch formed from a liquid-jet source in vacuum. The principal advantage of this pinch over a laser is both its simplicity and its ability to efficiently produce high-power vacuum ultraviolet radiation. The laser-guided gas-embedded pinch vacuum-ultraviolet source has been converted to a liquid-jet configuration in vacuum. This was undertaken for several reasons. First, the necessity of interposed high-density background gas is avoided. Second, a channel-forming guide laser beam is no longer needed. Finally, a wide variety of high-Z low cost substances are available in liquid form. For these reasons the liquid-jet approach makes sense for a rep-rate version of the pinch illuminator. Background gas absorption of hard UV is lessened. A large gas-transport system is not needed. Radiation output may be optimized through selection of the liquid's vapor pressure, surface tension, density, and composition.

  4. Z-Pinch Plasma Neutron Sources

    DTIC Science & Technology

    2006-03-24

    6. 0. A. Anderson, W. R. Baker, S. A. Colgate , H. P. Furth, J. Ise, R. V. Pyle and R. E. Wright, "Neutron production in a linear deuterium pinch...34 Phys. Rev. 109, 612 (1958). 7. 0. A. Anderson, W. R. Baker, S. A. Colgate , H. P. Furth, J. Ise, and R. V. Pyle, "Neutron production in linear deuterium

  5. Microtearing modes in reversed field pinch plasmas.

    PubMed

    Predebon, I; Sattin, F; Veranda, M; Bonfiglio, D; Cappello, S

    2010-11-05

    In the reversed field pinch RFX-mod strong electron temperature gradients develop when the single-helical-axis regime is achieved. Gyrokinetic calculations show that in the region of the strong temperature gradients microtearing instabilities are the dominant turbulent mechanism acting on the ion Larmor radius scale. The quasilinear evaluation of the electron thermal conductivity is in good agreement with the experimental estimates.

  6. Magnetic pinch compression of silica glass

    NASA Technical Reports Server (NTRS)

    Bless, S. J.

    1974-01-01

    SiO2 glass has been irreversibly densified by pressures up to 250 kbar produced in a magnetic pinch apparatus. The threshold for significant densification was about 60 kbar. The recovered densities agree better with published shock wave results than with static results.

  7. Spectroscopic study in Z-pinch discharge

    SciTech Connect

    Garamoon, A.A.; Saudy, A.H.; Shark, W.

    1995-12-31

    The temporal variation of the emitted line intensity has been investigated, and thus an important information about the dynamic ionization stages in the Z-pinch discharge has been studied. Also the electron temperature Te, has been deduced by using a spectroscopic technique.

  8. The Pinch Pot Technique and Raku.

    ERIC Educational Resources Information Center

    Demery, Marie

    Since the 16th century, the small Japanese raku tea bowl has reflected the merged cultural influences of art, religion, and other countries on the art of Japanese pottery. Artistically, the bowl is a combination of ceramics (pinching) and sculpture (carving). The dictates of the Zen Buddhist tea masters determine its sculptural process and steps,…

  9. The Pinch Pot Technique and Raku.

    ERIC Educational Resources Information Center

    Demery, Marie

    Since the 16th century, the small Japanese raku tea bowl has reflected the merged cultural influences of art, religion, and other countries on the art of Japanese pottery. Artistically, the bowl is a combination of ceramics (pinching) and sculpture (carving). The dictates of the Zen Buddhist tea masters determine its sculptural process and steps,…

  10. Dynamics of hybrid X-pinches

    SciTech Connect

    Shelkovenko, T. A.; Tilikin, I. N.; Ivanenkov, G. V.; Stepniewski, W.; Mingaleev, A. R.; Romanova, V. M.; Agafonov, A. V.; Cahill, A. D.; Hoyt, C. L.; Gourdain, P. A.; Hammer, D. A.; Pikuz, S. A.

    2015-01-15

    The dynamics of a new type of pinches—hybrid X-pinches (HXPs)—has been studied experimentally and numerically. The initial configuration of an HXP consists of a high-current diode with conical tungsten electrodes separated by a 1- to 3-mm-long gap and shunted with a 20- to 100-μm diameter wire. It was shown earlier that a hot spot (HS) with high plasma parameters also formed in the HXP, although its initial configuration is simpler than that of a standard X-pinch. Although details of the HXP dynamics still remain insufficiently studied, the main factors governing the HXP formation were investigated both experimentally and using magnetohydrodynamic simulations. The formation of a specific pressure profile in the electrode plasma after the wire explosion was investigated both experimentally and theoretically. It is shown that the effect of the pressure profile on the expanding wire plasma is similar for both standard X-pinches and HXPs, which allows one to assign them to the same class of loads of pulsed facilities. It is also established that the final stages of HS formation and the parameters of the HS plasma in standard X-pinches and HXPs are practically identical.

  11. Characterization of laser-cut copper foil X-pinches

    NASA Astrophysics Data System (ADS)

    Collins, G. W.; Valenzuela, J. C.; Hansen, S. B.; Wei, M. S.; Reed, C. T.; Forsman, A. C.; Beg, F. N.

    2016-10-01

    Quantitative data analyses of laser-cut Cu foil X-pinch experiments on the 150 ns quarter-period, ˜250 kA GenASIS driver are presented. Three different foil designs are tested to determine the effects of initial structure on pinch outcome. Foil X-pinch data are also presented alongside the results from wire X-pinches with comparable mass. The X-ray flux and temporal profile of the emission from foil X-pinches differed significantly from that of wire X-pinches, with all emission from the foil X-pinches confined to a ˜3 ns period as opposed to the delayed, long-lasting electron beam emission common in wire X-pinches. Spectroscopic data show K-shell as well as significant L-shell emission from both foil and wire X-pinches. Fits to synthetic spectra using the SCRAM code suggest that pinching foil X's produced a ˜1 keV, ne ≥ 1023 cm-3 plasma. The spectral data combined with the improved reliability of the source timing, flux, and location indicate that foil X-pinches generate a reproducible, K-shell point-projection radiography source that can be easily modified and tailored to suit backlighting needs across a variety of applications.

  12. CASEIN VISCOSITY STUDIES

    PubMed Central

    Zoller, Harper F.

    1921-01-01

    1. Viscosity and pH curves of casein dissolved in NaOH, KOH, LiOH, and NH4OH are shown and it is found that a maximum viscosity occurs at about the same pH point with each alkali; i.e., 9.1 to 9.25. The magnitude of the viscosity is largest in ammonia solutions. 2. The maximum viscosity occurs in 8 to 10 per cent solutions of casein in alkalies when about 98 x 10–5 gram equivalents of base are combined with 1 gram of casein. 3. A maximum viscosity occurs in the same region (pH 9.1 to 9.25) when casein is dissolved in Na2CO3, Na3AsO4, Na2SO3, NaF, and Na2PO3. 4. The maximum viscosity obtained with borax solutions of casein occurs at 8.15 to 8.2 pH. It is suggested that casein acts like mannitol, glycerol, etc., in increasing the dissociation of boric acid. 5. The flattening of the viscosity curves of casein solutions, following the decline from maximum, is shown to be due to alkaline hydrolysis whence casein no longer exists as such but is cleaved into a major protein containing no phosphorus or sulfur and less nitrogen. This cleavage commences at pH 10.0 to 10.5. 6. When casein is prepared from solutions that have been subjected to high temperatures (60°C. and above) or has otherwise been heated during its preparation, it yields solutions in alkalies of high viscosity. PMID:19871893

  13. Two-dimensional structure and particle pinch in tokamak H mode.

    PubMed

    Kasuya, Naohiro; Itoh, Kimitaka

    2005-05-20

    Two-dimensional structures of the electrostatic potential, density, and flow velocity near the edge of a tokamak plasma are investigated. The model includes the nonlinearity in bulk-ion viscosity and turbulence-driven shear viscosity. For the case with the strong radial electric field (H mode), a two-dimensional structure in a transport barrier is obtained, giving a poloidal shock with a solitary radial electric field profile. The inward particle pinch is induced from this poloidal asymmetric electric field, and increases as the radial electric field becomes stronger. The abrupt increase of this inward ion and electron flux at the onset of L- to H-mode transition explains the rapid establishment of the density pedestal, which is responsible for the observed spontaneous self-reorganization into an improved confinement regime.

  14. Two-Dimensional Structure and Particle Pinch in Tokamak H Mode

    SciTech Connect

    Kasuya, Naohiro; Itoh, Kimitaka

    2005-05-20

    Two-dimensional structures of the electrostatic potential, density, and flow velocity near the edge of a tokamak plasma are investigated. The model includes the nonlinearity in bulk-ion viscosity and turbulence-driven shear viscosity. For the case with the strong radial electric field (H mode), a two-dimensional structure in a transport barrier is obtained, giving a poloidal shock with a solitary radial electric field profile. The inward particle pinch is induced from this poloidal asymmetric electric field, and increases as the radial electric field becomes stronger. The abrupt increase of this inward ion and electron flux at the onset of L- to H-mode transition explains the rapid establishment of the density pedestal, which is responsible for the observed spontaneous self-reorganization into an improved confinement regime.

  15. Differentially Rotating White Dwarfs I: Regimes of Internal Rotation

    NASA Astrophysics Data System (ADS)

    Ghosh, Pranab; Wheeler, J. Craig

    2017-01-01

    Most viable models of Type Ia supernovae (SNe Ia) require the thermonuclear explosion of a carbon/oxygen white dwarf that has evolved in a binary system. Rotation could be an important aspect of any model for SNe Ia, whether single or double degenerate, with the white dwarf mass at, below, or above the Chandrasekhar limit. Differential rotation is specifically invoked in attempts to account for the apparent excess mass in the super-Chandrasekhar events. Some earlier work has suggested that only uniform rotation is consistent with the expected mechanisms of angular momentum transport in white dwarfs, while others have found pronounced differential rotation. We show that if the baroclinic instability is active in degenerate matter and the effects of magnetic fields are neglected, both nearly uniform rotation and strongly differential rotation are possible. We classify rotation regimes in terms of the Richardson number, Ri. At small values of Ri ≤slant 0.1, we find both the low-viscosity Zahn regime with a nonmonotonic angular velocity profile and a new differential rotation regime for which the viscosity is high and scales linearly with the shear, σ. Employment of Kelvin–Helmholtz viscosity alone yields differential rotation. Large values of Ri ≫ 1 produce a regime of nearly uniform rotation for which the baroclinic viscosity is of intermediate value and scales as {σ }3. We discuss the gap in understanding of the behavior at intermediate values of Ri and how observations may constrain the rotation regimes attained by nature.

  16. Failure analysis of pinch-torsion tests as a thermal runaway risk evaluation method of Li-Ion Cells

    SciTech Connect

    Xia, Yuzhi; Li, Dr. Tianlei; Ren, Prof. Fei; Gao, Yanfei; Wang, Hsin

    2014-01-01

    Recently a pinch-torsion test is developed for safety testing of Li-ion batteries (Ren et al., J. Power Source, 2013). It has been demonstrated that this test can generate small internal short-circuit spots in the separator in a controllable and repeatable manner. In the current research, the failure mechanism is examined by numerical simulations and comparisons to experimental observations. Finite element models are developed to evaluate the deformation of the separators under both pure pinch and pinch-torsion loading conditions. It is discovered that the addition of the torsion component significantly increased the maximum principal strain, which is believed to induce the internal short circuit. In addition, the applied load in the pinch-torsion test is significantly less than in the pure pinch test, thus dramatically improving the applicability of this method to ultra-thick batteries which otherwise require heavy load in excess of machine capability. It is further found that the separator failure is achieved in the early stage of torsion (within a few degree of rotation). Effect of coefficient of friction on the maximum principal strain is also examined.

  17. Turbulent viscosity. [in accretion disks

    NASA Technical Reports Server (NTRS)

    Canuto, V. M.; Goldman, I.; Chasnov, J.

    1988-01-01

    A model for fully developed turbulence is proposed whose predictions compare favorably with those of the direct interaction approximation (DIA) model and whose main equations are easy to handle. Four different expressions for the turbulent viscosity are derived which contain no free parameters. Two of the expressions are given in terms of properties of the turbulent fluid itself; the other two are given in terms of the instability that generated the turbulence and of the properties of the mean flow. The numerical coefficients entering these relations are evaluated and found to be in good agreement with previous theoretical estimates based on Kraichnan's DIA, the renormalization group method, and turbulence modeling. In the case of shear in the mean flow, the Shakura-Sunyaev alpha parameter is shown to be less than 0.01. The four expressions can be generalized to include the effect of rotation and/or magnetic fields.

  18. Increasing Plasma Parameters using Sheared Flow Stabilization of a Z-Pinch

    NASA Astrophysics Data System (ADS)

    Shumlak, Uri

    2016-10-01

    Recent experiments on the ZaP Flow Z-Pinch at the University of Washington have been successful in compressing the plasma column to smaller radii, producing the predicted increases in plasma density (1018 cm-3), temperature (200 eV), and magnetic fields (4 T), while maintaining plasma stability for many Alfven times (over 40 μs) using sheared plasma flows. These results indicate the suitability of the device as a discovery science platform for astrophysical and high energy density plasma research, and keeps open a possible path to achieving burning plasma conditions in a compact fusion device. Long-lived Z-pinch plasmas have been produced with dimensions of 1 cm radius and 100 cm long that are stabilized by sheared axial flows for over 1000 Alfven radial transit times. The observed plasma stability is coincident with the presence of a sheared flow as measured by time-resolved multi-chord ion Doppler spectroscopy applied to impurity ion radiation. These measurements yield insights into the evolution of the velocity profile and show that the stabilizing behavior of flow shear agrees with theoretical calculations and 2-D MHD computational simulations. The flow shear value, extent, and duration are shown to be consistent with theoretical models of the plasma viscosity, which places a design constraint on the maximum axial length of a sheared flow stabilized Z-pinch. Measurements of the magnetic field topology indicate simultaneous azimuthal symmetry and axial uniformity along the entire 100 cm length of the Z-pinch plasma. Separate control of plasma acceleration and compression have increased the accessible plasma parameters and have generated stable plasmas with radii below 0.5 cm, as measured with a high resolution digital holographic interferometer. This work was supported by Grants from U.S. DOE, NNSA, and ARPA-E.

  19. Regimes of Internal Rotation in Differentially Rotating White Dwarfs

    NASA Astrophysics Data System (ADS)

    Wheeler, J. Craig; Ghosh, Pranab

    2017-01-01

    Most viable models of Type Ia supernovae (SN Ia) require the thermonuclear explosion of a carbon/oxygen white dwarf that has evolved in a binary system. Rotation could be an important aspect of any model for SN Ia, whether single or double degenerate, with the white dwarf mass at, below, or above the Chandrasekhar limit. Differential rotation is specifically invoked in attempts to account for the apparent excess mass in the super--Chandrasekhar events. Some earlier work has suggested that only uniform rotation is consistent with the expected mechanisms of angular momentum transport in white dwarfs, while others have found pronounced differential rotation. We show that if the baroclinic instability is active in degenerate matter and the effects of magnetic fields are neglected, both nearly-uniform and strongly-differential rotation are possible. We classify rotation regimes in terms of the Richardson number, Ri. At small values of Ri < 0.1, we find both the low-viscosity Zahn regime with a non-monotonic angular velocity profile and a new differential rotation regime for which the viscosity is high and scales linearly with the shear, σ. Employment of Kelvin-Helmholtz viscosity alone yields differential rotation. Large values of Ri >> 1 produce a regime of nearly-uniform rotation for which the baroclinic viscosity is of intermediate value and scales as σ3. We discuss the gap in understanding of the behavior at intermediate values of Ri and how observations may constrain the rotation regimes attained by nature.

  20. Imaging aerosol viscosity

    NASA Astrophysics Data System (ADS)

    Pope, Francis; Athanasiadis, Thanos; Botchway, Stan; Davdison, Nicholas; Fitzgerald, Clare; Gallimore, Peter; Hosny, Neveen; Kalberer, Markus; Kuimova, Marina; Vysniauskas, Aurimas; Ward, Andy

    2017-04-01

    Organic aerosol particles play major roles in atmospheric chemistry, climate, and public health. Aerosol particle viscosity is important since it can determine the ability of chemical species such as oxidants, organics or water to diffuse into the particle bulk. Recent measurements indicate that OA may be present in highly viscous states; however, diffusion rates of small molecules such as water appear not to be limited by these high viscosities. We have developed a technique for measuring viscosity that allows for the imaging of aerosol viscosity in micron sized aerosols through use of fluorescence lifetime imaging of viscosity sensitive dyes which are also known as 'molecular rotors'. These rotors can be introduced into laboratory generated aerosol by adding minute quantities of the rotor to aerosol precursor prior to aerosolization. Real world aerosols can also be studied by doping them in situ with the rotors. The doping is achieved through generation of ultrafine aerosol particles that contain the rotors; the ultrafine aerosol particles deliver the rotors to the aerosol of interest via impaction and coagulation. This work has been conducted both on aerosols deposited on microscope coverslips and on particles that are levitated in their true aerosol phase through the use of a bespoke optical trap developed at the Central Laser Facility. The technique allows for the direct observation of kinetic barriers caused by high viscosity and low diffusivity in aerosol particles. The technique is non-destructive thereby allowing for multiple experiments to be carried out on the same sample. It can dynamically quantify and track viscosity changes during atmospherically relevant processes such oxidation and hygroscopic growth (1). This presentation will focus on the oxidation of aerosol particles composed of unsaturated and saturated organic species. It will discuss how the type of oxidant, oxidation rate and the composition of the oxidized products affect the time

  1. Polytropic scaling of a flow Z-pinch

    NASA Astrophysics Data System (ADS)

    Hughes, M. C.; Shumlak, U.; Nelson, B. A.; Golingo, R. P.; Claveau, E. L.; Doty, S. A.; Forbes, E. G.; Kim, B.; Ross, M. P.; Weed, J. R.

    2015-11-01

    The ZaP Flow Z-Pinch project investigates the use of velocity shear to mitigate MHD instabilities. The ZaP-HD experiment produces 50 cm long pinches of varying radii. The power to the experiment is split between the plasma formation and acceleration process and the pinch assembly and compression process. Once the pinch is formed, low magnetic fluctuations indicate a quiescent, long-lived pinch. The split power supply allows more control of the pinch current than previous machine iterations, with a designed range from 50 to 150 kA. Radial force balance leads to the Bennett relation which indicates that as the pinch compresses due to increasing currents, the plasma pressure and/or linear density must change. Through ion spectroscopy and digital holographic interferometry coupled with magnetic measurements of the pinch current, the components of the Bennett relation can be fully measured. A scaling relation is then assumed to follow a polytrope as the pinch pressure, initially approximately 250 kPa, increases from an initially formed state to much higher values, approaching 100 MPa. A preliminary analysis of pinch scaling is shown corroborating with other diagnostics on the machine along with extrapolations to required currents for an HEDLP machine. This work is supported by grants from the U.S. Department of Energy and the U.S. National Nuclear Security Administration.

  2. Viscosity in Saturn's rings

    NASA Technical Reports Server (NTRS)

    Lissauer, J. J.; Shu, F. H.; Cuzzi, J. N.

    1982-01-01

    The technique of estimating the viscosity in Saturn's rings from the damping rate of waves observed to be propagating within the rings is discussed. The wavetrains of attempts using spiral density waves as a diagnostic suffer significant complications that compromise the interpretations. A method that considers the damping of spiral bending waves was used to deduce a kinematic viscosity of 260 (+150, -100) sqcm/sec for the middle of the A ring where bending waves are excited by the 5:3 vertical resonance with Mimas. This value implies upper limits on the particle velocity dispersion and local ring thickness of 0.4 cm/sec and 30 m, respectively.

  3. ROTATING PLASMA DEVICE

    DOEpatents

    Boyer, K.; Hammel, J.E.; Longmire, C.L.; Nagle, D.E.; Ribe, F.L.; Tuck, J.L.

    1961-10-24

    ABS>A method and device are described for obtaining fusion reactions. The basic concept is that of using crossed electric and magnetic fields to induce a plasma rotation in which the ionized particles follow a circumferential drift orbit on wldch a cyclotron mode of motion is superimposed, the net result being a cycloidal motion about the axis of symmetry. The discharge tube has a radial electric field and a longitudinal magnetic field. Mirror machine geometry is utilized. The device avoids reliance on the pinch effect and its associated instability problems. (AEC)

  4. Spectroscopic investigation of highly transient pinch plasmas

    SciTech Connect

    Bergmann, K.; Engel, A.; Lebert, R.; Rosmej, O.N.; Rosmej, F.B.; Gavrilescu, C.; Neff, W.

    1997-11-01

    The temporal evolution of neon pinch plasmas, generated in a 2 kJ plasma focus device, has been investigated by x-ray spectroscopic methods for two sets of device parameters. These two sets lead to characteristic differences of the K-shell emission. Stationary models are shown to fail to explain the experimental observations even qualitatively. Transient spectra analysis shows that the characteristic differences observed can be referred to different transient modes of plasma dynamics. The spectra analysis includes beside resonance lines also dielectronic satellites and recombination continua. The results concerning the development of the plasma parameters achieved by the spectra modeling are supported by independent measurements of the time resolved K-shell emission and by optical streak images of the pinch plasma dynamics, which confirms the reliability of the transient spectroscopic analysis presented. {copyright} {ital 1997} {ital The American Physical Society}

  5. Compression mechanisms in the plasma focus pinch

    NASA Astrophysics Data System (ADS)

    Lee, S.; Saw, S. H.; Ali, Jalil

    2017-03-01

    The compression of the plasma focus pinch is a dynamic process, governed by the electrodynamics of pinch elongation and opposed by the negative rate of change of current dI/dt associated with the current dip. The compressibility of the plasma is influenced by the thermodynamics primarily the specific heat ratio; with greater compressibility as the specific heat ratio γ reduces with increasing degree of freedom f of the plasma ensemble due to ionization energy for the higher Z (atomic number) gases. The most drastic compression occurs when the emitted radiation of a high-Z plasma dominates the dynamics leading in extreme cases to radiative collapse which is terminated only when the compressed density is sufficiently high for the inevitable self-absorption of radiation to occur. We discuss the central pinch equation which contains the basic electrodynamic terms with built-in thermodynamic factors and a dQ/dt term; with Q made up of a Joule heat component and absorption-corrected radiative terms. Deuterium is considered as a thermodynamic reference (fully ionized perfect gas with f = 3) as well as a zero-radiation reference (bremsstrahlung only; with radiation power negligible compared with electrodynamic power). Higher Z gases are then considered and regimes of thermodynamic enhancement of compression are systematically identified as are regimes of radiation-enhancement. The code which incorporates all these effects is used to compute pinch radius ratios in various gases as a measure of compression. Systematic numerical experiments reveal increasing severity in radiation-enhancement of compressions as atomic number increases. The work progresses towards a scaling law for radiative collapse and a generalized specific heat ratio incorporating radiation.

  6. Electroweak pinch technique to all orders

    NASA Astrophysics Data System (ADS)

    Binosi, Daniele

    2004-09-01

    The generalization of the pinch technique to all orders in the electroweak sector of the Standard Model within the class of the renormalizable 't Hooft gauges, is presented. In particular, both the all-order PT gauge-boson- and scalar-fermion vertices, as well as the diagonal and mixed gauge-boson and scalar self-energies are explicitly constructed. This is achieved through the generalization to the Standard Model of the procedure recently applied to the QCD case, which consists of two steps: (i) the identification of special Green's functions, which serve as a common kernel to all self-energy and vertex diagrams and (ii) the study of the (on-shell) Slavnov-Taylor identities they satisfy. It is then shown that the ghost, scalar and scalar-gauge-boson Green's functions appearing in these identities capture precisely the result of the pinching action at arbitrary order. It turns out that the aforementioned Green's functions play a crucial role, their net effect being the non-trivial modification of the ghost, scalar and scalar-gauge-boson diagrams of the gauge-boson- or scalar-fermion vertex we have started from, in such a way as to dynamically generate the characteristic ghost and scalar sector of the background field method. The pinch technique gauge-boson and scalar self-energies are also explicitly constructed by resorting to the method of the background-quantum identities.

  7. Staged Z-pinch for Fusion

    NASA Astrophysics Data System (ADS)

    Wessel, Frank; Rahman, Hafiz; Ney, Paul; Darling, Tim; McKee, Erik; Covington, Aaron; Beg, Farhat; Valenzuela, Julio; Narkis, Jeff; Presura, Radu

    2015-11-01

    The Staged Z-pinch (SZP) is configured as a plasma shell imploding onto an uniform, plasma fill (50:50 Deuterium:Tritium); the pinch is pre-magnetized, with an axial Bz field. Gas-puff experiments, at the University of California, Irvine, 1.25 MA, 1.25 μs, and 50 kJ, demonstrated that the implosion was stable, as primary (DD) and secondary (DT) neutrons were produced at peak compression. Subsequent analysis accounts for the stability and neutron yield, indicating that the SZP implosion is magneto-inertial, shock-driven, with magneto-sonic shocks in the liner and ordinary (sonic) shocks in the target. The shock waves preheat the target, as a stable, current-carrying, shock front forms at the interface. Near-term, the SZP team will test pinch loads on the 1 MA, 130 ns, 100 kJ University of Nevada, Reno, Nevada Terawatt, Zebra Facility. This paper details the context and our specific plans for the upcoming experiments, as well as our recent simulations predicting breakeven fusion on existing devices. Funded by the US Department of Energy, ARPA-E, Control Number 1184-1527.

  8. Studies of the Plasma Triggering Mechanism of Inverse Pinch Switch

    DTIC Science & Technology

    1993-11-10

    Studies of the Plasma Puff Triggering Mechanism 02 of Inverse Pinch Switch AD-A276 117 Final Report ElEC 0 A Principal Investigator Kwang S. Han Nov...based on a hypocycloidal pinch geometry was investigated to determine the optimal operating conditions for the azimuthally uniform surface flashover ...in the switch . In this study, the plasma-puff triggering mechanism based on a hypocycloidal pinch geometry was investigated to determine the optimal

  9. Viscosity of colloidal suspensions

    SciTech Connect

    Cohen, E.G.D.; Schepper, I.M. de

    1995-12-31

    Simple expressions are given for the effective Newtonian viscosity as a function of concentration as well as for the effective visco-elastic response as a function of concentration and imposed frequency, of monodisperse neutral colloidal suspensions over the entire fluid range. The basic physical mechanisms underlying these formulae are discussed. The agreement with existing experiments is very good.

  10. Toe Pinch Force in Male Type 2 Diabetes Mellitus Patients.

    PubMed

    Kataoka, Hiroaki; Miyatake, Nobuyuki; Kitayama, Naomi; Murao, Satoshi; Tanaka, Satoshi

    2017-04-01

    We compared the toe pinch force in men with and without type 2 diabetes mellitus (T2DM). Sixty-eight male T2DM patients and 35 apparently healthy men matched for age, sex, and body mass index (BMI) were enrolled in this cross-sectional study. We compared the toe pinch force between the subjects with and without T2DM, and we evaluated the effect of diabetic polyneuropathy on toe pinch force in the patients. The toe pinch force of the T2DM patients was significantly lower than that of the subjects without diabetes (3.12±1.22 kg vs. 4.40±1.19 kg, p<0.001). Multiple regression analysis showed that T2DM was a determinant of reduced toe pinch force. In addition, the toe pinch force of patients with diabetic polyneuropathy was significantly lower than that of patients without diabetic polyneuropathy (2.31±0.93 kg vs. 3.70±1.07 kg, p<0.001). Multiple regression analysis showed that diabetic polyneuropathy was a determinant of the toe pinch force in men with T2DM, even after adjusting for age, BMI, HbA1c, and duration of diabetes. Reduced toe pinch force is a fundamental feature of motor dysfunction in men with T2DM, and diabetic polyneuropathy might be associated with toe pinch force in these patients.

  11. Study of Jet Formation in Wire X-pinches

    SciTech Connect

    Beg, F.N.; Ross, I.; Zhu, Y.; Dangor, A.E.; Krushelnick, K.

    2006-01-05

    Observations of x-pinch discharges driven by the 160 kA, 80 ns IMP generator are reported. X-pinches consisting of two wires of aluminum and molybdenum were used. X-pinches were mounted at two angles (120 deg. and 83 deg. ). The coronal plasma from the wires was observed to be streaming towards the mid plane of an x-pinch, forming jets on either side of the cross-point. Streaming of the coronal plasma was significant for a narrow angle and jets were observed to be m=1 unstable indicating a transfer of current.

  12. Effective viscosity of dilute bacterial suspensions

    NASA Astrophysics Data System (ADS)

    Haines, Brian M.

    self-propulsion once more provided by a point force. Furthermore, the bacterium is subject to a random torque in order to model tumbling (random reorientation). This model is used to calculate the effective viscosity of the suspension from the microscopic details of the interaction of an elongated body with a prescribed background flow, once more in the dilute limit. Due to a bacterium's asymmetric shape (in particular, unlike the case of rotationally symmetric bacteria used in the first model), interactions with generic planar background flows cause the bacterium to preferentially align in certain directions. Due to the random torque, the steady-state distribution of orientations is unique for a given background flow. Under this distribution of orientations, self-propulsion produces a reduction in the effective viscosity. For sufficiently weak background flows, the effect of self-propulsion on the effective viscosity dominates all other contributions, leading to an effective viscosity of the suspension that is lower than the viscosity of the ambient fluid. This is in qualitative agreement with recent experiments on suspensions of Bacillus subtilis. Finally, we present a method that can be used to rigorously justify our effective viscosity formulae. In particular, we present a mathematical proof of Einstein's formula for the effective viscosity of a dilute suspension of spheres when the spheres are centered on the vertices of a cubic lattice. This proof admits a generalization to other particle shapes and the inclusion of self-propulsion. We keep the size of the container finite in the dilute limit and consider boundary effects. Einstein's formula is recovered as a first-order asymptotic expansion of the effective viscosity in the volume fraction o. To rigorously justify this expansion, we obtain an explicit upper and lower bound on the effective viscosity and show that they match to order o3/2.

  13. Bulk viscosity effects on ultrasonic thermoacoustic instability

    NASA Astrophysics Data System (ADS)

    Lin, Jeffrey; Scalo, Carlo; Hesselink, Lambertus

    2016-11-01

    We have carried out unstructured fully-compressible Navier-Stokes simulations of a minimal-unit traveling-wave ultrasonic thermoacoustic device in looped configuration. The model comprises a thermoacoustic stack with 85% porosity and a tapered area change to suppress the fundamental standing-wave mode. A bulk viscosity model, which accounts for vibrational and rotational molecular relaxation effects, is derived and implemented via direct modification of the viscous stress tensor, τij ≡ 2 μSij +λ/2 μ ∂uk/∂xk δij , where the bulk viscosity is defined by μb ≡ λ +2/3 μ . The effective bulk viscosity coefficient accurately captures acoustic absorption from low to high ultrasonic frequencies and matches experimental wave attenuation rates across five decades. Using pressure-based similitude, the model was downscaled from total length L = 2 . 58 m to 0 . 0258 m, corresponding to the frequency range f = 242 - 24200 Hz, revealing the effects of bulk viscosity and direct modification of the thermodynamic pressure. Simulations are carried out to limit cycle and exhibit growth rates consistent with linear stability analyses, based on Rott's theory.

  14. Critical Viscosity of Xenon

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Shear thirning will cause a normally viscous fluid -- such as pie filling or whipped cream -- to deform and flow more readily under high shear conditions. In shear thinning, a pocket of fluid will deform and move one edge forward, as depicted here.

  15. Critical Viscosity of Xenon

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Shear thirning will cause a normally viscous fluid -- such as pie filling or whipped cream -- to deform and flow more readily under high shear conditions. In shear thinning, a pocket of fluid will deform and move one edge forward, as depicted here.

  16. Viscosity of human bile sampled from the common bile duct.

    PubMed

    Reinhart, Walter H; Näf, Gabriela; Werth, Baseli

    2010-01-01

    Cholestasis is a frequent gastroenterological problem, which is tackled by endoscopic procedures. Little is known about bile viscosity, a major determinant of its flow. We measured the viscosity of bile from the common bile duct during endoscopic retrograde cholangiography. Bile was aspirated immediately after cannulation of the papilla and deep-frozen. Viscosity was measured with a rotational viscometer at 37 degrees C and a broad range of shear rates (0.08-69.5 s(-1)). The majority of the 138 patients (64.5%) had bile viscosities between water (0.7 mPa.s) and the lower limit of plasma (1.1 mPa.s). In 20 patients (14.5%) it was above that of plasma (>1.4 mPa.s), and showed a non-Newtonian behaviour, i.e. the viscosity increased exponentially with decreasing shear rate. Cholecystectomized patients had a lower bile viscosity. Bile viscosities did not differ between patient groups with either choledocholithiasis, sludge, cholangitis, biliary pancreatitis, pancreatic carcinoma, or cholangiocarcinoma. We conclude that bile viscosity in the common bile duct is usually lower than that of plasma, in 15% it is higher and increases exponentially with decreasing flow rate, which may lead to a vicious cycle.

  17. Nonlocal Transport in the Reversed Field Pinch

    SciTech Connect

    Spizzo, G.; White, R. B.; Cappello, S.; Marrelli, L.

    2009-09-21

    Several heuristic models for nonlocal transport in plasmas have been developed, but they have had a limited possibility of detailed comparision with experimental data. Nonlocal aspects introduced by the existence of a known spectrum of relatively stable saturated tearing modes in a low current reversed field pinch offers a unique possibility for such a study. A numerical modelling of the magnetic structure and associated particle transport is carried out for the reversed-field pinch experiment at the Consorzio RFX, Padova, Italy. A reproduction of the tearing mode spectrum with a guiding center code1 reliably reproduces the observed soft X-ray tomography. Following particle trajectories in the stochastic magnetic field shows the transport across the unperturbed flux surfaces to be due to a spectrum of Levy flights, with the details of the spectrum position dependent. The resulting transport is subdiffusive, and cannot be described by Rechester-Rosenbluth diffusion, which depends on a random phase approximation. If one attempts to fit the local transport phenomenologically, the subdiffusion can be fit with a combination of diffusion and inward pinch2. It is found that whereas passing particles explore the stochastic field and hence participate in Levy flights, the trapped particles experience normal neoclassical diffusion. A two fluid nonlocal Montroll equation is used to model this transport, with a Levy flight defined as the motion of an ion during the period that the pitch has one sign. The necessary input to the Montroll equation consists of a time distribution for the Levy flights, given by the pitch angle scattering operator, and a distribution of the flight distances, determined numerically using a guiding center code. Results are compared to experiment. The relation of this formulation to fractional kinetics is also described.

  18. Investigation on the pinch point position in heat exchangers

    NASA Astrophysics Data System (ADS)

    Pan, Lisheng; Shi, Weixiu

    2016-06-01

    The pinch point is important for analyzing heat transfer in thermodynamic cycles. With the aim to reveal the importance of determining the accurate pinch point, the research on the pinch point position is carried out by theoretical method. The results show that the pinch point position depends on the parameters of the heat transfer fluids and the major fluid properties. In most cases, the pinch point locates at the bubble point for the evaporator and the dew point for the condenser. However, the pinch point shifts to the supercooled liquid state in the near critical conditions for the evaporator. Similarly, it shifts to the superheated vapor state with the condensing temperature approaching the critical temperature for the condenser. It even can shift to the working fluid entrance of the evaporator or the supercritical heater when the heat source fluid temperature is very high compared with the absorbing heat temperature. A wrong position for the pinch point may generate serious mistake. In brief, the pinch point should be founded by the iterative method in all conditions rather than taking for granted.

  19. What is a Reversed Field Pinch?

    NASA Astrophysics Data System (ADS)

    Escande, D. F.

    2015-12-01

    The following sections are included: * Introduction * Short description * Usefulness of the RFP configuration for fusion science and dynamo physics * Attractivity of the RFP configuration for a reactor * Challenges ahead * Lawson criterion * Intuitive model of magnetic self-reversal * Intuitive description of the dynamo * Necessity of a helical deformation * MHD simulations * From single to multiple helicity * Single helicity * Multiple helicity * Quasi single helicity * Experimental results * Multiple helicity * Quasi single helicity * Upgrade of the RFX device * From double to single magnetic axis * Analytical description of the single helicity RFP * Helical Grad-Shafranov equation * Parallel Ohm's law * Pinch-stellarator equation * Single helicity ohmic RFP states * Calculation of the dynamo * Conclusion * Acknowledgments * References

  20. Z-pinch plasma neutron sources

    SciTech Connect

    Velikovich, A. L.; Clark, R. W.; Davis, J.; Chong, Y. K.; Deeney, C.; Coverdale, C. A.; Ruiz, C. L.; Cooper, G. W.; Nelson, A. J.; Franklin, J.; Rudakov, L. I.

    2007-02-15

    A deuterium gas-puff load imploded by a multi-MA current driver from a large initial diameter could be a powerful source of fusion neutrons, a plasma neutron source (PNS). Unlike the beam-target neutrons produced in Z-pinch plasmas in the 1950s and deuterium-fiber experiments in the 1980s, the neutrons generated in deuterium gas-puffs with current levels achieved in recent experiments on the Z facility at Sandia National Laboratories could contain a substantial fraction of thermonuclear origin. For recent deuterium gas-puff shots on Z, our analytic estimates and one- and two-dimensional simulations predict thermal neutron yields {approx}3x10{sup 13}, in fair agreement with the yields recently measured on Z [C. A. Coverdale et al., Phys. Plasmas (to be published)]. It is demonstrated that the hypothesis of a beam-target origin of the observed fusion neutrons implies a very high Z-pinch-driver-to-fast-ions energy transfer efficiency, 5 to 10%, which would make a multi-MA deuterium Z-pinch the most efficient light-ion accelerator. No matter what mechanism is eventually determined to be responsible for generating fusion neutrons in deuterium gas-puff shots on Z, the deuterium neutron yield is shown to scale as Y{sub n}{approx}I{sub m}{sup 4}, where I{sub m} is the peak current of the pinch. Theoretical estimates and numerical modeling of deuterium gas-puff implosions demonstrate that the yields of thermonuclear fusion neutrons that can be produced on ZR and the next-generation machines are sufficiently high to make PNS the most powerful, cost- and energy-efficient laboratory sources of 2.5-14 MeV fusion neutrons, just like plasma radiation sources are the most powerful sources of soft and keV x rays. In particular, the predicted deuterium-tritium thermal neutron-producing capability of PNS driven by the next-generation ZR and ZX accelerators is {approx}5x10{sup 16} and {approx}10{sup 18}, respectively.

  1. Supersonic gas shell for puff pinch experiments

    NASA Astrophysics Data System (ADS)

    Smith, R. S., III; Doggett, W. O.; Roth, I.; Stallings, C.

    1982-09-01

    An easy-to-fabricate, conical, annular supersonic nozzle has been developed for use in high-power, puff gas z-pinch experiments. A fast responding conical pressure probe has also been developed as an accurate supersonic gas flow diagnostic for evaluating the transient gas jet formed by the nozzle. Density profile measurements show that the magnitude and radial position of the gas annulus are fairly constant with distance from the nozzle, but the gas density in the center of the annulus increases with distance from the nozzle.

  2. Quasilinear transport due to the magnetic drift resonance with the ion temperature gradient instability in a rotating plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Debing; Xu, Yingfeng; Wang, Shaojie

    2017-08-01

    The quasilinear transport fluxes due to the ion temperature gradient instability are calculated in a toroidal plasma, in which the magnetic drift resonance is treated rigorously. The effects of the equilibrium parallel flow and flow shear on the radial particle and heat fluxes are studied numerically in detail. In the radial component of parallel viscosity, there exist the pinches driven by the density gradient, the temperature gradient, and the curvature of the background magnetic field. The direction of these pinches is discussed. It is found that each pinch can be inward or outward, which depends crucially on the resonance condition.

  3. Pinched flow fractionation of microbubbles for ultrasound contrast agent enrichment

    NASA Astrophysics Data System (ADS)

    Versluis, Michel; Kok, Maarten; Segers, Tim

    2014-11-01

    An ultrasound contrast agent (UCA) suspension contains a wide size distribution of encapsulated microbubbles (typically 1-10 μm in diameter) that resonate to the driving ultrasound field by the intrinsic relationship between bubble size and ultrasound frequency. Medical transducers, however, operate in a narrow frequency range, which severely limits the number of bubbles that contribute to the echo signal. Thus, the sensitivity can be improved by narrowing down the size distribution of the bubble suspension. Here, we present a novel, low-cost, lab-on-a-chip method for the sorting of contrast microbubbles by size, based on a microfluidic separation technique known as pinched flow fractionation (PFF). We show by experimental and numerical investigation that the inclusion of particle rotation is essential for an accurate physical description of the sorting behavior of the larger bubbles. Successful sorting of a bubble suspension with a narrow size distribution (3.0 +/- 0.6 μm) has been achieved with a PFF microdevice. This sorting technique can be easily parallelized, and may lead to a significant improvement in the sensitivity of contrast-enhanced medical ultrasound. This work is supported by NanoNextNL, a micro and nanotechnology consortium of the Government of the Netherlands and 130 partners.

  4. Photoacoustic measurement of liquid viscosity

    NASA Astrophysics Data System (ADS)

    Lou, Cunguang; Xing, Da

    2010-05-01

    In this letter, we report on the use of photoacoustic method to measure the viscosity of viscous liquids. The theoretical and experimental study was performed on the influence of viscosity effects on photoacoustic generation. We provide evidence that the frequency spectrum of photoacoustic signal is precisely related to the viscosity. Measurements are validated on different water-glycerol mixtures. Good agreement between theoretical and experimental results is obtained. This present method provides an insight into in situ viscosity measurements, which has potential for noninvasive detection of blood viscosity.

  5. Scaling of the Sheared-Flow Stabilized Z-Pinch: The Fusion Z-Pinch Experiment ``FuZE''

    NASA Astrophysics Data System (ADS)

    Nelson, B. A.; Shumlak, U.; Claveau, E. L.; Golingo, R. P.; Weber, T. R.; McLean, H. S.; Tummel, K. K.; Higginson, D. P.; Schmidt, A. E.; UW/LLNL Collaboration

    2016-10-01

    The sheared flow stabilized (SFS) Z-pinch ZaP experiment was constructed based on calculations [1] showing stabilization of kink and sausage instabilities. ZaP experimentally demonstrated production and sustainment of an SFS Z-pinch for a wide range of plasma parameters, with densities up to n =1023 m-3 and a pinch radius of a = 1 cm. [2-4] The SFS Z-pinch is resistant to the instabilities of conventional Z-pinches, yet maintains the same favorable radial scaling, making it an energy-efficient way to achieve fusion-relevant conditions. The ZaP-HD (high density) experiment has demonstrated scaling of the SFS Z-pinch to 2-3 × smaller a and 10 × higher n. [5] Supported by ZaP and ZaP-HD, the Fusion Z-pinch Experiment (FuZE) project investigates scaling plasma parameters toward fusion conditions by decreasing a 2-3 × to 1 mm, and increasing n 10 × to 1025 m-3. The approach combines improved gas injection and flexible power supplies with the successful ZaP SFS Z-pinch formation. Detailed fluid and kinetic simulations complement the experimental studies to gain scientific insight into the plasma behavior and predict scaling to higher performance. Supported by DoE FES, NNSA, and ARPA-E ALPHA.

  6. Fusion Propulsion Z-Pinch Engine Concept

    NASA Technical Reports Server (NTRS)

    Miernik, J.; Statham, G.; Fabisinski, L.; Maples, C. D.; Adams, R.; Polsgrove, T.; Fincher, S.; Cassibry, J.; Cortez, R.; Turner, M.; hide

    2011-01-01

    Fusion-based nuclear propulsion has the potential to enable fast interplanetary transportation. Due to the great distances between the planets of our solar system and the harmful radiation environment of interplanetary space, high specific impulse (Isp) propulsion in vehicles with high payload mass fractions must be developed to provide practical and safe vehicles for human spaceflight missions. The Z-Pinch dense plasma focus method is a Magneto-Inertial Fusion (MIF) approach that may potentially lead to a small, low cost fusion reactor/engine assembly1. Recent advancements in experimental and theoretical understanding of this concept suggest favorable scaling of fusion power output yield 2. The magnetic field resulting from the large current compresses the plasma to fusion conditions, and this process can be pulsed over short timescales (10(exp -6 sec). This type of plasma formation is widely used in the field of Nuclear Weapons Effects testing in the defense industry, as well as in fusion energy research. A Decade Module 2 (DM2), approx.500 KJ pulsed-power is coming to the RSA Aerophysics Lab managed by UAHuntsville in January, 2012. A Z-Pinch propulsion concept was designed for a vehicle based on a previous fusion vehicle study called "Human Outer Planet Exploration" (HOPE), which used Magnetized Target Fusion (MTF) 3 propulsion. The reference mission is the transport of crew and cargo to Mars and back, with a reusable vehicle.

  7. Analysis of pinching in deterministic particle separation

    NASA Astrophysics Data System (ADS)

    Risbud, Sumedh; Luo, Mingxiang; Frechette, Joelle; Drazer, German

    2011-11-01

    We investigate the problem of spherical particles vertically settling parallel to Y-axis (under gravity), through a pinching gap created by an obstacle (spherical or cylindrical, center at the origin) and a wall (normal to X axis), to uncover the physics governing microfluidic separation techniques such as deterministic lateral displacement and pinched flow fractionation: (1) theoretically, by linearly superimposing the resistances offered by the wall and the obstacle separately, (2) computationally, using the lattice Boltzmann method for particulate systems and (3) experimentally, by conducting macroscopic experiments. Both, theory and simulations, show that for a given initial separation between the particle centre and the Y-axis, presence of a wall pushes the particles closer to the obstacle, than its absence. Experimentally, this is expected to result in an early onset of the short-range repulsive forces caused by solid-solid contact. We indeed observe such an early onset, which we quantify by measuring the asymmetry in the trajectories of the spherical particles around the obstacle. This work is partially supported by the National Science Foundation Grant Nos. CBET- 0731032, CMMI-0748094, and CBET-0954840.

  8. Critical Viscosity of Xenon

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Because xenon near the critical point will collapse under its own weight, experiments on Earth (green line) are limited as they get closer (toward the left) to the critical point. CVX in the microgravity of space (red line) moved into unmeasured territory that scientists had not been able to reach.

  9. Viscosity Destabilizes Sonoluminescing Bubbles

    NASA Astrophysics Data System (ADS)

    Toegel, Ruediger; Luther, Stefan; Lohse, Detlef

    2006-03-01

    In single-bubble sonoluminescence (SBSL) microbubbles are trapped in a standing sound wave, typically in water or water-glycerol mixtures. However, in viscous liquids such as glycol, methylformamide, or sulphuric acid it is not possible to trap the bubble in a stable position. This is very peculiar as larger viscosity normally stabilizes the dynamics. Suslick and co-workers call this new mysterious state of SBSL “moving-SBSL.” We identify the history force (a force nonlocal in time) as the origin of this destabilization and show that the instability is parametric. A force balance model quantitatively accounts for the observed quasiperiodic bubble trajectories.

  10. Viscosity destabilizes sonoluminescing bubbles.

    PubMed

    Toegel, Ruediger; Luther, Stefan; Lohse, Detlef

    2006-03-24

    In single-bubble sonoluminescence (SBSL) microbubbles are trapped in a standing sound wave, typically in water or water-glycerol mixtures. However, in viscous liquids such as glycol, methylformamide, or sulphuric acid it is not possible to trap the bubble in a stable position. This is very peculiar as larger viscosity normally stabilizes the dynamics. Suslick and co-workers call this new mysterious state of SBSL "moving-SBSL." We identify the history force (a force nonlocal in time) as the origin of this destabilization and show that the instability is parametric. A force balance model quantitatively accounts for the observed quasiperiodic bubble trajectories.

  11. Critical Viscosity of Xenon

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The sample cell at the heart of CVX-2 will sit inside a thermostat providing three layers of insulation. The cell itself comprises a copper body that conducts heat efficiently and smoothes out thermal variations that that would destroy the xenon's uniformity. Inside the cell, the oscillating screen viscometer element is supported between two pairs of electrodes that deflect the screen and then measure screen motion.

  12. Critical Viscosity of Xenon

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2001 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The thermostat for CVX sits inside the white cylinder on a support structure that is placed inside a pressure canister. A similar canister holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (not shown) of the National Institutes of Standards and Technology, Gaithersburg, MD. This is a detail view of MSFC 0100143.

  13. Critical Viscosity of Xenon

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Because xenon near the critical point will collapse under its own weight, experiments on Earth (green line) are limited as they get closer (toward the left) to the critical point. CVX in the microgravity of space (red line) moved into unmeasured territory that scientists had not been able to reach.

  14. Age-Related and Sex-Related Differences in Hand and Pinch Grip Strength in Adults

    ERIC Educational Resources Information Center

    Puh, Urska

    2010-01-01

    The purpose of the study was to quantify age-related changes in hand grip strength and three types of pinch grip strength (key pinch, tip pinch, and palmar pinch) among male and female participants. The study included 199 healthy participants (100 females, 99 males) aged 20-79 years, who were divided into four age groups. The Baseline Hydraulic…

  15. The thermo magnetic instability in hot viscose plasmas

    NASA Astrophysics Data System (ADS)

    Haghani, A.; Khosravi, A.; Khesali, A.

    2017-10-01

    Magnetic Rotational Instability (MRI) can not performed well in accretion disks with strong magnetic field. Studies have indicated a new type of instability called thermomagnetic instability (TMI) in systems where Nernst coefficient and gradient temperature were considered. Nernst coefficient would appear if Boltzman equation could be expanded through ω_{Be} (cyclotron frequency). However, the growth rate of this instability was two magnitude orders below MRI growth (Ωk), which could not act the same as MRI. Therefor, a higher growth rate of unstable modes was needed. In this paper, rotating viscid hot plasma with strong magnetic filed was studied. Firstly, a constant alpha viscosity was studied and then a temperature sensitive viscosity. The results showed that the temperature sensitive viscosity would be able to increase the growth rate of TMI modes significantly, hence capable of acting similar to MRI.

  16. The determination of viscosity at liquid mixtures - Comparison of approaches

    NASA Astrophysics Data System (ADS)

    Michal, Schmirler; Hana, Netřebská; Jan, Kolínský

    2017-09-01

    The research of flow field parameters for non-stationary flow of non-Newtonian fluids carried out at the Institute of Fluid Mechanics and Thermodynamics of CTU showed the need for knowledge of determination of the resulting viscosity of a mixture of several liquids. There are several sources for determining viscosity of mixtures. It is possible either to find theoretical relations in the literature or use technical tables based on experimentally measured data. This article focuses on comparing these approaches with an experiment. The experiment was performed by a Rheotest RN 4.1 rotating viscometer produced by the company RHEOTEST Medingen. The research was carried out using a solution of glycerol and water. The research has shown great differences in results in different approaches for determining the viscosity of the liquid mixtures. The result of this paper is to determine the method of viscosity calculation that is closest to the experimental data.

  17. Progress in Z-pinch inertial fusion energy.

    SciTech Connect

    Weed, John Woodruff

    2010-03-01

    The goal of z-pinch inertial fusion energy (IFE) is to extend the single-shot z-pinch inertial confinement fusion (ICF) results on Z to a repetitive-shot z-pinch power plant concept for the economical production of electricity. Z produces up to 1.8 MJ of x-rays at powers as high as 230 TW. Recent target experiments on Z have demonstrated capsule implosion convergence ratios of 14-21 with a double-pinch driven target, and DD neutron yields up to 8x10exp10 with a dynamic hohlraum target. For z-pinch IFE, a power plant concept is discussed that uses high-yield IFE targets (3 GJ) with a low rep-rate per chamber (0.1 Hz). The concept includes a repetitive driver at 0.1 Hz, a Recyclable Transmission Line (RTL) to connect the driver to the target, high-yield targets, and a thick-liquid wall chamber. Recent funding by a U.S. Congressional initiative for $4M for FY04 is supporting research on RTLs, repetitive pulsed power drivers, shock mitigation, full RTL cycle planned experiments, high-yield IFE targets, and z-pinch power plant technologies. Recent results of research in all of these areas are discussed, and a Road Map for Z-Pinch IFE is presented.

  18. Note: Infrared laser diagnostics for deuterium gas puff Z pinches

    NASA Astrophysics Data System (ADS)

    Ivanov, V. V.; McKee, E. S.; Hammel, B. D.; Darling, T. W.; Swanson, K. J.; Covington, A. M.

    2017-07-01

    Deuterium gas puff Z pinches have been used for generation of strong neutron fluxes on the MA class pulse power machines. Due to the low electron density of deuterium Z-pinch plasma, regular laser diagnostics in the visible range cannot be used for observation and study of the pinch. Laser probing at the wavelength of 1064 nm was used for visualization of deuterium plasma. Infrared schlieren and interferometry diagnostics showed the deuterium gas puff plasma dynamics, instabilities, and allowed for the reconstruction of the profile of the plasma density.

  19. Analysis of the energetic parameters of a theta pinch

    NASA Astrophysics Data System (ADS)

    Cavalcanti, G. H.; Farias, E. E.

    2009-12-01

    This work is devoted to study experimentally the performance of a theta pinch when the number of capacitors and turns of magnetic coil and the diameter of the glass tube are changed. To model the theta pinch a simple RLC circuit is used and the measurement of energy transmission from the bank of capacitors to the plasma is made using few experimental resources. In this work it was analyzed more than 2500 curves with a nonlinear procedure. Our results show that it is possible to design an optimized theta pinch making the appropriated choice of energetic parameters and therefore to reduce the stress of the system.

  20. Development of an updated pinch-welding capability. Final report

    SciTech Connect

    Samayoa, J.A.

    1993-02-01

    An updated pinch-welding capability was developed. The work included development and implementation of unique tooling (70556200-T0l) to allow reproduction of the Savannah River Plant (SRP) confined pinch-welding process using a 3-phase, 100 KVA resistance welder. The new process replaced an existing process in use at KCD since about 1978. A statistical experiment was designed and utilized to define the operational envelope of the new process and to define acceptable machine parameters to produce the pinch-weld. An acceptance criteria for production welds was developed and implemented.

  1. Development of an updated pinch-welding capability

    SciTech Connect

    Samayoa, J.A.

    1993-02-01

    An updated pinch-welding capability was developed. The work included development and implementation of unique tooling (70556200-T0l) to allow reproduction of the Savannah River Plant (SRP) confined pinch-welding process using a 3-phase, 100 KVA resistance welder. The new process replaced an existing process in use at KCD since about 1978. A statistical experiment was designed and utilized to define the operational envelope of the new process and to define acceptable machine parameters to produce the pinch-weld. An acceptance criteria for production welds was developed and implemented.

  2. Viscosity of the earth's core.

    NASA Technical Reports Server (NTRS)

    Gans, R. F.

    1972-01-01

    Calculation of the viscosity of the core at the boundary of the inner and outer core. It is assumed that this boundary is a melting transition and the viscosity limits of the Andrade (1934,1952) hypothesis (3.7 to 18.5 cp) are adopted. The corresponding kinematic viscosities are such that the precessional system explored by Malkus (1968) would be unstable. Whether it would be sufficiently unstable to overcome a severely subadiabatic temperature gradient cannot be determined.

  3. Viscosity of the earth's core.

    NASA Technical Reports Server (NTRS)

    Gans, R. F.

    1972-01-01

    Calculation of the viscosity of the core at the boundary of the inner and outer core. It is assumed that this boundary is a melting transition and the viscosity limits of the Andrade (1934,1952) hypothesis (3.7 to 18.5 cp) are adopted. The corresponding kinematic viscosities are such that the precessional system explored by Malkus (1968) would be unstable. Whether it would be sufficiently unstable to overcome a severely subadiabatic temperature gradient cannot be determined.

  4. Pinching solutions of slender cylindrical jets

    NASA Technical Reports Server (NTRS)

    Papageorgiou, Demetrios T.; Orellana, Oscar

    1993-01-01

    Simplified equations for slender jets are derived for a circular jet of one fluid flowing into an ambient second fluid, the flow being confined in a circular tank. Inviscid flows are studied which include both surface tension effects and Kelvin-Helmholtz instability. For slender jets a coupled nonlinear system of equations is found for the jet shape and the axial velocity jump across it. The equations can break down after a finite time and similarity solutions are constructed, and studied analytically and numerically. The break-ups found pertain to the jet pinching after a finite time, without violation of the slender jet ansatz. The system is conservative and admissible singular solutions are those which conserve the total energy, mass, and momentum. Such solutions are constructed analytically and numerically, and in the case of vortex sheets with no surface tension certain solutions are given in closed form.

  5. Viscosity measuring instrument

    NASA Technical Reports Server (NTRS)

    Feinstein, S. P. (Inventor)

    1980-01-01

    A method and apparatus are provided for enabling the measurement of the viscosity of substances, especially those containing volatiles at elevated temperatures, with greater accuracy and at less cost than before. The apparatus includes a cylinder with a narrow exit opening at one end and a piston which closely slides within the cylinder to apply force against a sample in the cylinder to force the sample through the exit opening. In order to more rapidly heat a sample the ends of the cylinder and piston are tapered and the sample is correspondingly tapered, to provide a large surface to volume ratio. A corresponding coal sample is formed by compressing particles of coal under high pressure in a mold of appropriate shape.

  6. Critical Viscosity of Xenon

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of liquid xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Resembling a tiny bit of window screen, the oscillator at the heart of CVX-2 will vibrate between two pairs of paddle-like electrodes. The slight bend in the shape of the mesh has no effect on the data. What counts are the mesh's displacement in the xenon fluid and the rate at which the displacement dampens. The unit shown here is encased in a small test cell and capped with a sapphire windown to contain the xenon at high pressure.

  7. Shear viscosity of inhomogeneous fluids.

    PubMed

    Hoang, Hai; Galliero, Guillaume

    2012-03-28

    Using molecular dynamics simulations on inhomogeneous fluids, we have studied the effects of strong density inhomogeneities of varying wavelengths on the shear viscosity computed locally. For dense fluids, the local average density model combined with an adequate weight function yields a good description of the viscosity profiles obtained by simulations. However, for low density inhomogeneous fluids, the local average density model is unable to describe correctly the viscosity profiles obtained by simulations. It is shown that this weakness can be overcome by taking into account the density inhomogeneity in the local translational contribution to the viscosity using a density gradient like approach.

  8. Negative-viscosity lattice gases

    SciTech Connect

    Rothman, D.H. )

    1989-08-01

    A new irreversible collision rule is introduced for lattice-gas automata. The rule maximizes the flux of momentum in the direction of the local momentum gradient, yielding a negative shear viscosity. Numerically results in 2D show that the negative viscosity leads to the spontaneous ordering of the velocity field, with vorticity resolvable down to one lattice-link length. The new rule may be used in conjunction with previously proposed collision rules to yield a positive shear viscosity lower than the previous rules provide. In particular, Poiseuille flow tests demonstrate a decrease in viscosity by more than a factor of 2.

  9. Formation of liquid drops at an orifice and dynamics of pinch-off in liquid jets

    NASA Astrophysics Data System (ADS)

    Borthakur, Manash Pratim; Biswas, Gautam; Bandyopadhyay, Dipankar

    2017-07-01

    This paper presents a numerical investigation of the dynamics of pinch-off in liquid drops and jets during injection of a liquid through an orifice into another fluid. The current study is carried out by solving axisymmetric Navier-Stokes equations and the interface is captured using a coupled level-set and volume-of-fluid approach. The delicate interplay of inertia and viscous effects plays a crucial role in deciding the dynamics of the formation as well as breakup of liquid drops and jets. In the dripping regime, the growth and breakup rate of a drop are studied and quantified by corroborating with theoretical predictions. During the growth stage of the drops, a self-similar behavior of the drop profile is identified over a relatively short duration of time. The viscosity of the drop liquid shows substantial influence on the thinning behavior of a liquid neck and a transition is observed from an inertia dominated regime to an inertia-viscous regime beyond a critical minimum value of the neck radius. The phenomenon of interface overturning is fundamentally related to the magnitude of drop viscosity. The variation of overturning angle as a function of drop viscosity is computed and a critical value of Ohnesorge number is obtained beyond which overturning ceases. Increasing the inertia of drop liquid transforms the system from a periodically dripping regime to a quasiperiodic regime and finally it culminates into an elongated liquid jet. Another interesting transition from dripping to jetting regime is demonstrated by varying the viscosity of the ambient medium. The breakup of jets in Rayleigh mode is explored and the breakup length obtained from our computations shows excellent agreement with the theoretical predictions owing to Rayleigh's analysis. The ambient medium is entrained as the jet moves downstream with the creation of a vortical structure just outside the jet signifying increased participation of the ambient medium in the dynamics of jet breakup at

  10. Methods of Viscosity Measurements in Sealed Ampoules

    NASA Technical Reports Server (NTRS)

    Mazuruk, Konstantin

    1999-01-01

    Viscosity of semiconductor and metallic melts is usually measured by oscillating cup method. This method utilizes the melts contained in vacuum sealed silica ampoules, thus the problems related to volatility, contamination, and high temperature and pressure can be alleviated. In a typical design, the time required for a single measurement is of the order of one hour. In order to reduce this time to a minute range, a high resolution (0.05 arc.sec) angular detection system is implemented in our design of the viscometer. Furthermore, an electromagnet generating a rotational magnetic field (RMF) is incorporated into the apparatus. This magnetic field can be used to remotely and non intrusively measure the electrical conductivity of the melt. It can also be used to induce a well controlled rotational flow in the system. The transient behavior of this flow can potentially yield the viscosity of the fluid. Based on RMF implementation, two novel viscometry methods are proposed in this work: a) the transient torque method, b) the resonance method. A unified theoretical approach to the three methods (oscillating cup, transient torque, and resonance) is presented along with the initial test results of the constructed apparatus. Advantages of each of the method are discussed.

  11. Methods of Viscosity Measurements in Sealed Ampoules

    NASA Technical Reports Server (NTRS)

    Mazuruk, Konstantin

    1999-01-01

    Viscosity of semiconductor and metallic melts is usually measured by oscillating cup method. This method utilizes the melts contained in vacuum sealed silica ampoules, thus the problems related to volatility, contamination, and high temperature and pressure can be alleviated. In a typical design, the time required for a single measurement is of the order of one hour. In order to reduce this time to a minute range, a high resolution (0.05 arc.sec) angular detection system is implemented in our design of the viscometer. Furthermore, an electromagnet generating a rotational magnetic field (RMF) is incorporated into the apparatus. This magnetic field can be used to remotely and non intrusively measure the electrical conductivity of the melt. It can also be used to induce a well controlled rotational flow in the system. The transient behavior of this flow can potentially yield the viscosity of the fluid. Based on RMF implementation, two novel viscometry methods are proposed in this work: a) the transient torque method, b) the resonance method. A unified theoretical approach to the three methods (oscillating cup, transient torque, and resonance) is presented along with the initial test results of the constructed apparatus. Advantages of each of the method are discussed.

  12. Effective viscosity of magnetic nanofluids through capillaries.

    PubMed

    Patel, Rajesh

    2012-02-01

    The simultaneous effect of magnetic field and temperature on the capillary viscosity of magnetic nanofluid is an important parameter for a new class of applications such as nanoduct flow, nanomotors, micro- and nanofluidic devices, for transformer cooling, magnetic targeted drug delivery, etc. The effective viscosity of a nanofluid is explained based on the rotation of the particles and the effect of torque on it due to an externally applied magnetic field. Two types of fluids are used here, temperature-sensitive and non-temperature-sensitive magnetic nanofluids. In both types of fluids, decrease in effective viscosity with temperature is observed, but in both cases the mechanism for the decrement is quite different. One is due to temperature dependence of the magnetic moment and the other is due to removal of the secondary surfactant. For temperature-sensitive magnetic nanofluids, a Curie temperature of ~80 °C is extracted from this study. For non-temperature-sensitive magnetic nanofluids ~65% of the secondary surfactant is removed for a change in temperature, ΔT = 40 °C. This is analogous with removal of a drug from magnetic particles for targeted drug delivery. Further, a linear dependence of effective viscosity with different capillary size and ξ (angle between magnetic field and flow direction, ξε[0,π/2]) is also observed. This linear dependence can also be a good approximation for the study of magnetic drug targeting, as in the human body the capillaries are of different sizes, and the externally applied magnetic field is not always parallel or perpendicular to the drug flow direction.

  13. Effective viscosity of magnetic nanofluids through capillaries

    NASA Astrophysics Data System (ADS)

    Patel, Rajesh

    2012-02-01

    The simultaneous effect of magnetic field and temperature on the capillary viscosity of magnetic nanofluid is an important parameter for a new class of applications such as nanoduct flow, nanomotors, micro- and nanofluidic devices, for transformer cooling, magnetic targeted drug delivery, etc. The effective viscosity of a nanofluid is explained based on the rotation of the particles and the effect of torque on it due to an externally applied magnetic field. Two types of fluids are used here, temperature-sensitive and non-temperature-sensitive magnetic nanofluids. In both types of fluids, decrease in effective viscosity with temperature is observed, but in both cases the mechanism for the decrement is quite different. One is due to temperature dependence of the magnetic moment and the other is due to removal of the secondary surfactant. For temperature-sensitive magnetic nanofluids, a Curie temperature of ˜80 ∘C is extracted from this study. For non-temperature-sensitive magnetic nanofluids ˜65% of the secondary surfactant is removed for a change in temperature, ΔT = 40 ∘C. This is analogous with removal of a drug from magnetic particles for targeted drug delivery. Further, a linear dependence of effective viscosity with different capillary size and ξ (angle between magnetic field and flow direction, ξ∈[0,π/2]) is also observed. This linear dependence can also be a good approximation for the study of magnetic drug targeting, as in the human body the capillaries are of different sizes, and the externally applied magnetic field is not always parallel or perpendicular to the drug flow direction.

  14. The TITAN reversed-field-pinch fusion reactor study

    SciTech Connect

    Not Available

    1990-01-01

    This paper on titan plasma engineering contains papers on the following topics: reversed-field pinch as a fusion reactor; parametric systems studies; magnetics; burning-plasma simulations; plasma transient operations; current drive; and physics issues for compact RFP reactors.

  15. A model code for the radiative theta pinch

    SciTech Connect

    Lee, S.; Saw, S. H.; Lee, P. C. K.; Akel, M.; Damideh, V.; Khattak, N. A. D.; Mongkolnavin, R.; Paosawatyanyong, B.

    2014-07-15

    A model for the theta pinch is presented with three modelled phases of radial inward shock phase, reflected shock phase, and a final pinch phase. The governing equations for the phases are derived incorporating thermodynamics and radiation and radiation-coupled dynamics in the pinch phase. A code is written incorporating correction for the effects of transit delay of small disturbing speeds and the effects of plasma self-absorption on the radiation. Two model parameters are incorporated into the model, the coupling coefficient f between the primary loop current and the induced plasma current and the mass swept up factor f{sub m}. These values are taken from experiments carried out in the Chulalongkorn theta pinch.

  16. A model code for the radiative theta pinch

    NASA Astrophysics Data System (ADS)

    Lee, S.; Saw, S. H.; Lee, P. C. K.; Akel, M.; Damideh, V.; Khattak, N. A. D.; Mongkolnavin, R.; Paosawatyanyong, B.

    2014-07-01

    A model for the theta pinch is presented with three modelled phases of radial inward shock phase, reflected shock phase, and a final pinch phase. The governing equations for the phases are derived incorporating thermodynamics and radiation and radiation-coupled dynamics in the pinch phase. A code is written incorporating correction for the effects of transit delay of small disturbing speeds and the effects of plasma self-absorption on the radiation. Two model parameters are incorporated into the model, the coupling coefficient f between the primary loop current and the induced plasma current and the mass swept up factor fm. These values are taken from experiments carried out in the Chulalongkorn theta pinch.

  17. Timing of x-ray burst from X-pinch

    SciTech Connect

    Zhao, Shen; Zhang, Ran; Zhu, Xinlei; Zou, Xiaobing; Wang, Xinxin

    2015-06-15

    The x-ray burst timings of X-pinches, T{sub XB}, made using eight different wires for different current were measured. The results showed that a higher current makes a shorter T{sub XB} for a given X-pinch wire. In other words, T{sub XB} scales linearly with the line mass density for a given current. Based on the snow-plow model for Z-pinch plasma, it was derived that for a given X-pinch wire the integral of the current over time from zero to T{sub XB} is constant, i.e., ∫{sub 0}{sup T{sub X}{sub B}}i(t)⋅dt=const.. This theoretically derived relation was confirmed by our experiments.

  18. A Characterization of the Radiation from a Rod-Pinch

    NASA Astrophysics Data System (ADS)

    Swanekamp, S. B.; Allen, R. J.; Hinshelwood, D. D.; Mosher, D.; Schumer, J. W.; Young, F. C.

    2001-10-01

    The rod pinch diode is being developed as an intense, x-ray source for high-resolution flash radiography. Recent experiments on the Asterix pulsed-power generator at the CEG in France have demonstrated rod-pinch operation with 2-4 MV endpoint voltages and have demonstrated doses of = 5-23 rads-Si at 1 meter with a 1-mm diameter spot size. A series of = simulations with the Integrated Tiger Series (ITS) electron/photon transport code = were performed to characterize the radiation from a rod-pinch. The electron-energy and incident-angle distributions on the tungsten rod = were input to ITS from MAGIC PIC predictions. These simulations give = information about the angular dependence of the radiation from the rod-pinch and the axial extent of the radiation source. The results from these simulations will be compared with radiation measurements from Asterix.

  19. Turbulent equipartition pinch of toroidal momentum in spherical torus

    NASA Astrophysics Data System (ADS)

    Hahm, T. S.; Lee, J.; Wang, W. X.; Diamond, P. H.; Choi, G. J.; Na, D. H.; Na, Y. S.; Chung, K. J.; Hwang, Y. S.

    2014-12-01

    We present a new analytic expression for turbulent equipartition (TEP) pinch of toroidal angular momentum originating from magnetic field inhomogeneity of spherical torus (ST) plasmas. Starting from a conservative modern nonlinear gyrokinetic equation (Hahm et al 1988 Phys. Fluids 31 2670), we derive an expression for pinch to momentum diffusivity ratio without using a usual tokamak approximation of B ∝ 1/R which has been previously employed for TEP momentum pinch derivation in tokamaks (Hahm et al 2007 Phys. Plasmas 14 072302). Our new formula is evaluated for model equilibria of National Spherical Torus eXperiment (NSTX) (Ono et al 2001 Nucl. Fusion 41 1435) and Versatile Experiment Spherical Torus (VEST) (Chung et al 2013 Plasma Sci. Technol. 15 244) plasmas. Our result predicts stronger inward pinch for both cases, as compared to the prediction based on the tokamak formula.

  20. Variability of precision pinch movements caused by carpal tunnel syndrome.

    PubMed

    Gehrmann, Sebastian; Tang, Jie; Kaufmann, Robert A; Goitz, Robert J; Windolf, Joachim; Li, Zong-Ming

    2008-09-01

    Carpal tunnel syndrome (CTS) impairs the performance of fine motor tasks of the hand, leading to clumsiness. Precision pinch by the thumb and index finger is a frequent task that requires the fine control of each digit as well as the coordination of the 2 digits. The purpose of this study was to examine the performance of precision pinch movements impaired by CTS. Sixteen CTS subjects and 16 gender- and age-matched control subjects were instructed to repetitively perform the precision pinch movement with the thumb and index finger. A marker-based motion analysis method was used to obtain the kinematic data of the thumb and index finger during the precision pinch movements. Pinch performance was quantified by the variability of tip positions, joint angles, and tip distance at the pinch closures in the repeated movements. The CTS subjects performed the precision pinch movements less consistently compared with performance of the control subjects. The inconsistency was demonstrated by the increased variability of the tip positions of the 2 digits and the joint angles of the index finger. However, the variability of thumb joint angles was not significantly different between the 2 groups. The tip-to-tip distance, an indicator of thumb and index finger coordination, was relatively reproducible for both groups. Still, the CTS subjects showed a 50% greater variability of the tip distance compared with that of the control subjects. Carpal tunnel syndrome impairs the performance of precision pinch movement as indicated by the increased variability. The results correlate with the observed clumsiness or lack of dexterity for patients with CTS.

  1. Experimental study of the neck formation in an X pinch

    NASA Astrophysics Data System (ADS)

    Artyomov, A. P.; Chaikovsky, S. A.; Fedunin, A. V.; Labetskaya, N. A.; Rousskikh, A. G.; Zhigalin, A. S.; Oreshkin, V. I.

    2014-11-01

    X-pinch experiments have been performed on a compact 250 kA, 180 ns pulsed power generator specially designed for this purpose at the Institute of High Current Electronics (Tomsk, Russia). The X pinches were composed of two molybdenum wires of diameter 25 μm making an angle of 36° with the z-axis. The X-pinch dynamics was recorded with a 3 ns exposure time using an HSFC Pro four-frame camera. Axial plasma jets propagating toward both the anode and the cathode were observed. The jets became noticeable within 10 ns after the onset of current flow, which approximately corresponded to the time at which the electrical explosion of the X-pinch wires occurred. The velocity of the anode-directed jet reached 107 cm/s, which was about 1.5 times the velocity of the cathode-directed jet. These high jet velocities are inconsistent with the plasma temperature resulting from the wire explosion. Hence, these jets seem to develop due to implosion of the light plasma layer stripped by magnetic forces from the wire surface, and the increase in their velocities is perhaps due to cumulative effects taking place at the X-pinch axis. The X-pinch neck formed as a rule above the initial wire cross point (closer to the anode). In this region, the plasma diameter gradually increased with time and then drastically decreased 10-15 ns prior to the x-ray pulse. Immediately before the x-ray pulse, in the (250-300 μm long) plasma neck, a lower scale constriction developed, forming a "hot spot". It has been confirmed that the anode-directed plasma jet could take some part of the X-pinch wire current because of the evident jet pinching in the anode region. This process seems to determine the neck length.

  2. Effective Viscosity Coefficient of Nanosuspensions

    NASA Astrophysics Data System (ADS)

    Rudyak, V. Ya.; Belkin, A. A.; Egorov, V. V.

    2008-12-01

    Systematic calculations of the effective viscosity coefficient of nanosuspensions have been performed using the molecular dynamics method. It is established that the viscosity of a nanosuspension depends not only on the volume concentration of the nanoparticles but also on their mass and diameter. Differences from Einstein's relation are found even for nanosuspensions with a low particle concentration.

  3. Low viscosity oils. [oxidation resistance

    SciTech Connect

    Harris, S.W.; Schaap, L.A.; Udelhofen, J.H.

    1981-08-04

    An improved low viscosity (I.E.) 5 W to 7 1/2 W engine oil resistant to oxidation and consumption comprising a major portion of a lubricating oil stock, a sulfurized oil, a dispersant, an anti-corrosion agent, an anti-rust agent, a detergent, an antioxidant, and a viscosity index improver.

  4. Viscosity range from one test

    SciTech Connect

    Singh, B.; Mutyala, S.; Puttagunta, V.R. )

    1990-09-01

    A simple and general correlation predicts viscosity of crude oils or their fractions by identifying the sensitivity of viscosity to changes of temperature as follows: (log({eta}) + C)/log({eta}{sub 0}) + C = (T{sub 0}/T){sup s} where {eta} = Kinematic viscosity, centistokes (cS); T = absolute temperature, {degrees}K; C = 0,86860, when the log base is 10; S = 0.28008*log({eta}{sub 0}) + 1.8616, when T{sub 0} = 310.93{degrees}K (100{degrees}F). The unique feature of this correlation is that an oil's viscosity can be predicted over a wide range of temperatures by having only a single viscosity measurement, {eta}{sub 0}, at some convenient temperature, T{sub 0}. In this case, the coefficients for S are given for T{sub 0} = 100{degrees}F. However, examples are given to show how to use the equation when the measured reference viscosity is at some other temperature. The predicted viscosity is at some other temperature. The predicted viscosity should be relatively precise, since an overall average absolute deviation of only 0.82% was determined using published experimental data.

  5. Volatiles Which Increase Magma Viscosity

    NASA Astrophysics Data System (ADS)

    Webb, S.

    2015-12-01

    The standard model of an erupting volcano is one in which the viscosity of a decompressing magma increases as the volatiles leave the melt structure to form bubbles. It has now been observed that the addition of the "volatiles" P, Cl and F result in an increase in silicate melt viscosity. This observation would mean that the viscosity of selected degassing magmas would decrease rather than increase. Here we look at P, Cl and F as three volatiles which increase viscosity through different structural mechanisms. In all three cases the volatiles increase the viscosity of peralkaline composition melts, but appear to always decrease the viscosity of peraluminous melts. Phosphorus causes the melt to unmix into a Na-P rich phase and a Na-poor silicate phase. Thus as the network modifying Na (or Ca) are removed to the phosphorus-rich melt, the matrix melt viscosity increases. With increasing amounts of added phosphorus (at network modifying Na ~ P) the addition of further phosphorus causes a decrease in viscosity. The addition of chlorine to Fe-free aluminosilicate melts results in an increase in viscosity. NMR data on these glass indicates that the chlorine sits in salt-like structures surrounded by Na and/or Ca. Such structures would remove network-modifying atoms from the melt structure and thus result in an increase in viscosity. The NMR spectra of fluorine-bearing glasses shows that F takes up at least 5 different structural positions in peralkaline composition melts. Three of these positions should result in a decrease in viscosity due to the removal of bridging oxygens. Two of the structural positons of F, however, should result in an increase in viscosity as they require the removal of network-modifying atoms from the melt structure (with one of the structures being that observed for Cl). This would imply that increasing amounts of F might result in an increase in viscosity. This proposed increase in viscosity with increasing F has now been experimentally confirmed.

  6. The ZaP Flow Z-Pinch Project

    NASA Astrophysics Data System (ADS)

    Shumlak, U.; Golingo, R. P.; Nelson, B. A.; Crawford, E. A.; Forbes, E. T.; den Hartog, D. J.; Holly, D. J.; Nagata, M.

    2000-10-01

    Linear analysis shows that a sheared axial plasma flow can stabilize the m=1 kink instability in Z-pinches. This threshold value of flow shear can be satisfied with a peak flow velocity which is less than the Alfven speed for wavelengths typically seen in Z-pinch plasmas. Nonlinear simulations support the stabilizing effect. The ZaP Flow Z-Pinch Project seeks to experimentally verify this theory by generating Z-pinch plasmas with an inherent axial flow. The experiment produces Z-pinch plasmas which are 50 cm in length by initiating the plasma with a one meter coaxial gun. The coaxial gun generates the axial plasma flows. After leaving the coaxial gun the plasma assembles along the axis to form a flow Z-pinch. Magnetic probes measure the acceleration and assembly process, as well as, the evolution of the azimuthal mode fluctuation level. Axial flow profiles are determined by measurements of the Doppler shifts of impurity lines. Time-dependent density measurements are made using a laser interferometer. Gross plasma motion is determined by using a fast framing camera to detect visible emission. Recent results show a period of diminished fluctuation level when the plasma flow velocity is large. An overview of the experimental program and results will be presented.

  7. Pinch-off Scaling Law of Soap Bubbles

    NASA Astrophysics Data System (ADS)

    Davidson, John; Ryu, Sangjin

    2014-11-01

    Three common interfacial phenomena that occur daily are liquid drops in gas, gas bubbles in liquid and thin-film bubbles. One aspect that has been studied for these phenomena is the formation or pinch-off of the drop/bubble from the liquid/gas threads. In contrast to the formation of liquid drops in gas and gas bubbles in liquid, thin-film bubble pinch-off has not been well documented. Having thin-film interfaces may alter the pinch-off process due to the limiting factor of the film thickness. We observed the pinch-off of one common thin-film bubble, soap bubbles, in order to characterize its pinch-off behavior. We achieved this by constructing an experimental model replicating the process of a human producing soap bubbles. Using high-speed videography and image processing, we determined that the minimal neck radius scaled with the time left till pinch-off, and that the scaling law exponent was 2/3, similar to that of liquid drops in gas.

  8. Conservative smoothing versus artificial viscosity

    SciTech Connect

    Guenther, C.; Hicks, D.L.; Swegle, J.W.

    1994-08-01

    This report was stimulated by some recent investigations of S.P.H. (Smoothed Particle Hydrodynamics method). Solid dynamics computations with S.P.H. show symptoms of instabilities which are not eliminated by artificial viscosities. Both analysis and experiment indicate that conservative smoothing eliminates the instabilities in S.P.H. computations which artificial viscosities cannot. Questions were raised as to whether conservative smoothing might smear solutions more than artificial viscosity. Conservative smoothing, properly used, can produce more accurate solutions than the von Neumann-Richtmyer-Landshoff artificial viscosity which has been the standard for many years. The authors illustrate this using the vNR scheme on a test problem with known exact solution involving a shock collision in an ideal gas. They show that the norms of the errors with conservative smoothing are significantly smaller than the norms of the errors with artificial viscosity.

  9. Calculator program predicts liquid viscosities

    SciTech Connect

    Arnold, V.E.

    1984-01-01

    In the absence of experimental data, the prediction of liquid viscosities for petroleum fractions can be a very difficult problem. In light of the complex nature of petroleum fractions and the difficulty of even identifying the components present in such a mixture, the standard methods generally used for estimating liquid viscosities from pure component data are not applicable. Yet some prediction method is necessary since fluid flow and heat transfer calculations depend on accurate viscosity estimates. Watson, et al., provided the pioneering work to fill this need by developing correlations capable of predicting viscosities at two or more temperatures solely from common petroleum fraction characterizing parameters. The API Data Book presents a convenient nomograph for determining the kinematic viscosity of petroleum fractions at 100/sup 0/ F. and 210/sup 0/ F. when only the Watson characterization factor and API of the cut are known. This nomograph is essentially a replotting of Watson's graphs in a more usable format.

  10. Kinetic versus ideal magnetohydrodynamic modelling of the resistive wall mode in a reversed field pinch plasma

    NASA Astrophysics Data System (ADS)

    Mulec, M.; Ivanov, I. B.; Heyn, M. F.; Kernbichler, W.

    2012-03-01

    Resistive wall modes (RWMs) are studied within the kinetic model proposed by Heyn et al. [Nucl. Fusion 46, S159 (2006); Phys. Plasmas 18, 022501 (2011)], which accounts for Landau damping, transit-time magnetic pumping, and Coulomb collisions in cylindrical geometry. Results for the reversed field pinch plasma are compared to the magnetohydrodynamic results obtained by Guo et al., [Phys. Plasmas 6, 3868 (1999)]. Stabilization of the external kink mode by an ideal wall as well as stabilization of the resistive wall mode by toroidal plasma rotation is obtained. In contrast to MHD modelling, which predicts a stability window for the resistive wall position, kinetic modelling predicts a one sided window only, i.e., the resistive wall must be sufficiently close to plasma to achieve rotational stabilization of the mode but there is no lower limit on the wall position. Stabilizing rotation speeds are found somewhat smaller when compared to MHD results. In addition, for the present plasma configuration, the kinetic model predicts resistive wall mode stabilization only in one direction of toroidal rotation. In the opposite direction, a destabilizing effect is observed. This is in contrast to MHD where mode stabilization is symmetric with respect to the direction of the toroidal plasma rotation.

  11. Plasma viscosity: a forgotten variable.

    PubMed

    Késmárky, Gábor; Kenyeres, Péter; Rábai, Miklós; Tóth, Kálmán

    2008-01-01

    Evaluation of plasma viscosity has been underutilized in the clinical practice. Plasma viscosity is determined by water-content and macromolecular components. Plasma is a highly concentrated protein solution, therefore weak protein-protein interactions can play a role that is not characterized by electrophoresis. The effect of a protein on plasma viscosity depends on its molecular weight and structure. The less spheroid shape, the higher molecular weight, the higher aggregating capacity, and the higher temperature or pH sensitivity a protein has, the higher plasma viscosity results. Plasma is a Newtonian fluid, its viscosity does not depend on flow characteristics, therefore it is simple to measure, especially in capillary viscosimeters. Its normal value is 1.10-1.30 mPa s at 37 degrees C and independent of age and gender. The measurement has high stability and accuracy, thus little alterations may be pathologically important. Inflammations, tissue injuries resulting in plasma protein changes can increase its value with high sensitivity, though low specificity. It can increase in parallel with erythrocyte sedimentation rate (ESR), but it is not influenced by hematocrit (anemia, polycytemia), or time to analysis. Based on these favorable features, in 1942 plasma viscosity was recommended to substitute ESR. In hyperviscosity syndromes plasma viscosity is better in follow-up than ESR. In rheumatoid arthritis, its sensitivity and specificity are better than that of ESR or C-reactive protein. Plasma fibrinogen concentration and plasma viscosity are elevated in unstable angina pectoris and stroke and their higher values are associated with higher rate of major adverse clinical events. Elevation of plasma viscosity correlates to the progression of coronary and peripheral artery diseases. In conclusion, plasma viscosity should be measured routinely in medical practice.

  12. Anomalous - viscosity current drive

    DOEpatents

    Stix, Thomas H.; Ono, Masayuki

    1988-01-01

    An apparatus and method for maintaining a steady-state current in a toroidal magnetically confined plasma. An electric current is generated in an edge region at or near the outermost good magnetic surface of the toroidal plasma. The edge current is generated in a direction parallel to the flow of current in the main plasma and such that its current density is greater than the average density of the main plasma current. The current flow in the edge region is maintained in a direction parallel to the main current for a period of one or two of its characteristic decay times. Current from the edge region will penetrate radially into the plasma and augment the main plasma current through the mechanism of anomalous viscosity. In another aspect of the invention, current flow driven between a cathode and an anode is used to establish a start-up plasma current. The plasma-current channel is magnetically detached from the electrodes, leaving a plasma magnetically insulated from contact with any material obstructions including the cathode and anode.

  13. Theoretical z -pinch scaling relations for thermonuclear-fusion experiments.

    PubMed

    Stygar, W A; Cuneo, M E; Vesey, R A; Ives, H C; Mazarakis, M G; Chandler, G A; Fehl, D L; Leeper, R J; Matzen, M K; McDaniel, D H; McGurn, J S; McKenney, J L; Muron, D J; Olson, C L; Porter, J L; Ramirez, J J; Seamen, J F; Speas, C S; Spielman, R B; Struve, K W; Torres, J A; Waisman, E M; Wagoner, T C; Gilliland, T L

    2005-08-01

    We have developed wire-array z -pinch scaling relations for plasma-physics and inertial-confinement-fusion (ICF) experiments. The relations can be applied to the design of z -pinch accelerators for high-fusion-yield (approximately 0.4 GJ/shot) and inertial-fusion-energy (approximately 3 GJ/shot) research. We find that (delta(a)/delta(RT)) proportional (m/l)1/4 (Rgamma)(-1/2), where delta(a) is the imploding-sheath thickness of a wire-ablation-dominated pinch, delta(RT) is the sheath thickness of a Rayleigh-Taylor-dominated pinch, m is the total wire-array mass, l is the axial length of the array, R is the initial array radius, and gamma is a dimensionless functional of the shape of the current pulse that drives the pinch implosion. When the product Rgamma is held constant the sheath thickness is, at sufficiently large values of m/l, determined primarily by wire ablation. For an ablation-dominated pinch, we estimate that the peak radiated x-ray power P(r) proportional (I/tau(i))(3/2)Rlphigamma, where I is the peak pinch current, tau(i) is the pinch implosion time, and phi is a dimensionless functional of the current-pulse shape. This scaling relation is consistent with experiment when 13 MA < or = I < or = 20 MA, 93 ns < or = tau(i) < or = 169 ns, 10 mm < or = R < or = 20 mm, 10 mm < or = l < or = 20 mm, and 2.0 mg/cm < or = m/l < or = 7.3 mg/cm. Assuming an ablation-dominated pinch and that Rlphigamma is held constant, we find that the x-ray-power efficiency eta(x) congruent to P(r)/P(a) of a coupled pinch-accelerator system is proportional to (tau(i)P(r)(7/9 ))(-1), where P(a) is the peak accelerator power. The pinch current and accelerator power required to achieve a given value of P(r) are proportional to tau(i), and the requisite accelerator energy E(a) is proportional to tau2(i). These results suggest that the performance of an ablation-dominated pinch, and the efficiency of a coupled pinch-accelerator system, can be improved substantially by decreasing the

  14. Method and device for measurement of dynamic viscosity

    NASA Astrophysics Data System (ADS)

    Ciornei, F. C.; Alaci, S.; Amarandei, D.; Irimescu, L.; Romanu, I. C.; Acsinte, L. I.

    2017-02-01

    The paper proposes a methodology and ensuing test rig for finding the viscosity of a liquid lubricant. The principle consists in obtaining a contact between two spherical surfaces, one concave and the other one convex. One of the surfaces is kept immobile and to the other, a rotation motion is imposed around the common normal in the contact point and then the law of motion for the mobile lens is found. The law of motion allows for estimation of friction torque, dependent on viscosity at its turn. Applying the method for mineral oils, values comparable to the ones presented by the producer were obtained.

  15. On the magnetic viscosity in Keplerian accretion disks

    NASA Technical Reports Server (NTRS)

    Coroniti, F. V.

    1981-01-01

    The paper develops a model for the anomalous viscosity in accretion disks based on the hypothesis that the hydrodynamic turbulence within the disk takes the form of spatially localized magnetic flux cells. The local shear flow due to Keplerian differential rotation distorts the flux cell topology, converting shear flow energy into magnetic energy. In the radial diffusion approximation, the kinematic viscosity is estimated from the radial displacement and is shown to maximize at flux cell scale lengths for which the shear flow stopping and reconnection times are equal.

  16. Extensional Relaxation Times and Pinch-off Dynamics of Dilute Polymer Solutions

    NASA Astrophysics Data System (ADS)

    Dinic, Jelena; Zhang, Yiran; Jimenez, Leidy; Sharma, Vivek

    2015-11-01

    We show that visualization and analysis of capillary-driven thinning and pinch-off dynamics of the columnar neck in an asymmetric liquid bridge created by dripping-onto-substrate can be used for characterizing the extensional rheology of complex fluids. Using a particular example of dilute, aqueous PEO solutions, we show the measurement of both the extensional relaxation time and extensional viscosity of weakly elastic, polymeric complex fluids with low shear viscosity η< 20 mPa .s and relatively short relaxation time, λ <1 ms. Characterization of elastic effects and extensional relaxation times in these dilute solutions is beyond the range measurable in the standard geometries used in commercially available shear and extensional rheometers (including CaBER, capillary breakup extensional rheometer). As the radius of the neck that connects a sessile drop to a nozzle is detected optically, and the extensional response for viscoelastic fluids is characterized by analyzing their elastocapillary self-thinning, we refer to this technique as optically-detected elastocapillary self-thinning dripping-onto-substrate (ODES-DOS) extensional rheometry.

  17. Plasma viscosity increase with progression of peripheral arterial atherosclerotic disease.

    PubMed

    Poredos, P; Zizek, B

    1996-03-01

    Increased blood and plasma viscosity has been described in patients with coronary and peripheral arterial disease. However, the relation of viscosity to the extent of arterial wall deterioration--the most important determinant of clinical manifestation and prognosis of the disease--is not well known. Therefore, the authors studied plasma viscosity as one of the major determinants of blood viscosity in patients with different stages of arterial disease of lower limbs (according to Fontaine) and its relation to the presence of some risk factors of atherosclerosis. The study encompassed four groups of subjects: 19 healthy volunteers (group A), 18 patients with intermittent claudication up to 200 m (stage II; group B), 15 patients with critical ischemia of lower limbs (stage III and IV; group C), and 16 patients with recanalization procedures on peripheral arteries. Venous blood samples were collected from an antecubital vein without stasis for the determination of plasma viscosity (with a rotational capillary microviscometer, PAAR), fibrinogen, total cholesterol, alpha-2-macroglobulin, and glucose concentrations. In patients with recanalization procedure local plasma viscosity was also determined from blood samples taken from a vein on the dorsum of the foot. Plasma viscosity was most significantly elevated in the patients with critical ischemia (1.78 mPa.sec) and was significantly higher than in the claudicants (1.68 mPa.sec), and the claudicants also had significantly higher viscosity than the controls (1.58 mPa.sec). In patients in whom a recanalization procedure was performed, no differences in systemic and local plasma viscosity were detected, neither before nor after recanalization of the diseased artery. In all groups plasma viscosity was correlated with fibrinogen concentration (r=0.70, P < 0.01) and total cholesterol concentration (r=0.24, P < 0.05), but in group C (critical ischemia) plasma viscosity was most closely linked to the concentration of alpha-2

  18. Z-Pinch Pulsed Plasma Propulsion Technology Development

    NASA Technical Reports Server (NTRS)

    Polsgrove, Tara; Adams, Robert B.; Fabisinski, Leo; Fincher, Sharon; Maples, C. Dauphne; Miernik, Janie; Percy, Tom; Statham, Geoff; Turner, Matt; Cassibry, Jason; Cortez, Ross; Santarius, John

    2010-01-01

    Fusion-based propulsion can enable fast interplanetary transportation. Magneto-inertial fusion (MIF) is an approach which has been shown to potentially lead to a low cost, small reactor for fusion break even. The Z-Pinch/dense plasma focus method is an MIF concept in which a column of gas is compressed to thermonuclear conditions by an axial current (I approximates 100 MA). Recent advancements in experiments and the theoretical understanding of this concept suggest favorable scaling of fusion power output yield as I(sup 4). This document presents a conceptual design of a Z-Pinch fusion propulsion system and a vehicle for human exploration. The purpose of this study is to apply Z-Pinch fusion principles to the design of a propulsion system for an interplanetary spacecraft. This study took four steps in service of that objective; these steps are identified below. 1. Z-Pinch Modeling and Analysis: There is a wealth of literature characterizing Z-Pinch physics and existing Z-Pinch physics models. In order to be useful in engineering analysis, simplified Z-Pinch fusion thermodynamic models are required to give propulsion engineers the quantity of plasma, plasma temperature, rate of expansion, etc. The study team developed these models in this study. 2. Propulsion Modeling and Analysis: While the Z-Pinch models characterize the fusion process itself, propulsion models calculate the parameters that characterize the propulsion system (thrust, specific impulse, etc.) The study team developed a Z-Pinch propulsion model and used it to determine the best values for pulse rate, amount of propellant per pulse, and mixture ratio of the D-T and liner materials as well as the resulting thrust and specific impulse of the system. 3. Mission Analysis: Several potential missions were studied. Trajectory analysis using data from the propulsion model was used to determine the duration of the propulsion burns, the amount of propellant expended to complete each mission considered. 4

  19. ZBLAN Viscosity Instrumentation

    NASA Technical Reports Server (NTRS)

    Kaukler, William

    2001-01-01

    The past year's contribution from Dr. Kaukler's experimental effort consists of these 5 parts: a) Construction and proof-of-concept testing of a novel shearing plate viscometer designed to produce small shear rates and operate at elevated temperatures; b) Preparing nonlinear polymeric materials to serve as standards of nonlinear Theological behavior; c) Measurements and evaluation of above materials for nonlinear rheometric behavior at room temperature using commercial spinning cone and plate viscometers available in the lab; d) Preparing specimens from various forms of pitch for quantitative comparative testing in a Dynamic Mechanical Analyzer, Thermal Mechanical Analyzer; and Archeological Analyzer; e) Arranging to have sets of pitch specimens tested using the various instruments listed above, from different manufacturers, to form a baseline of the viscosity variation with temperature using the different test modes offered by these instruments by compiling the data collected from the various test results. Our focus in this project is the shear thinning behavior of ZBLAN glass over a wide range of temperature. Experimentally, there are no standard techniques to perform such measurements on glasses, particularly at elevated temperatures. Literature reviews to date have shown that shear thinning in certain glasses appears to occur, but no data is available for ZBLAN glass. The best techniques to find shear thinning behavior require the application of very low rates of shear. In addition, because the onset of the thinning behavior occurs at an unknown elevated temperature, the instruments used in this study must provide controlled low rates of shear and do so for temperatures approaching 600 C. In this regard, a novel shearing parallel plate viscometer was designed and a prototype built and tested.

  20. Fluid Merging Viscosity Measurement (FMVM)

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Astronaut Mike Fincke places droplets of honey onto the strings for the Fluid Merging Viscosity Measurement (FMVM) investigation onboard the International Space Station (ISS). The FMVM experiment measures the time it takes for two individual highly viscous fluid droplets to coalesce or merge into one droplet. Different fluids and droplet size combinations were tested in the series of experiments. By using the microgravity environment, researchers can measure the viscosity or 'thickness' of fluids without the influence of containers and gravity using this new technique. Understanding viscosity could help scientists understand industrially important materials such as paints, emulsions, polymer melts and even foams used to produce pharmaceutical, food, and cosmetic products.

  1. Fluid Merging Viscosity Measurement (FMVM)

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Astronaut Mike Fincke places droplets of honey onto the strings for the Fluid Merging Viscosity Measurement (FMVM) investigation onboard the International Space Station (ISS). The FMVM experiment measures the time it takes for two individual highly viscous fluid droplets to coalesce or merge into one droplet. Different fluids and droplet size combinations were tested in the series of experiments. By using the microgravity environment, researchers can measure the viscosity or 'thickness' of fluids without the influence of containers and gravity using this new technique. Understanding viscosity could help scientists understand industrially important materials such as paints, emulsions, polymer melts and even foams used to produce pharmaceutical, food, and cosmetic products.

  2. Critical Viscosity of Xenon investigators

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Dr. Dr. Robert F. Berg (right), principal investigator and Dr. Micheal R. Moldover (left), co-investigator, for the Critical Viscosity of Xenon (CVX/CVX-2) experiment. They are with the National Institutes of Standards and Technology, Gaithersburg, MD. The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Although it does not easily combine with other chemicals, its viscosity at the critical point can be used as a model for a range of chemicals.

  3. MHD dynamo for the Reversed Field Pinch

    NASA Astrophysics Data System (ADS)

    Bonfiglio, Daniele; Cappello, Susanna; Escande, Dominique Frank; Spizzo, Gianluca

    2006-10-01

    MHD modelling is believed to provide a good description of large scale dynamics of the Reversed Field Pinch. In particular, 3-dimensional nonlinear simulations in a simple visco-resistive approximation [see Cappello PPCF 2004 and references therein] display many features in reasonable agreement with experiments. In recent times it has been shown that the general and basic tendency of the RFP to develop a more or less regular global kink type deformation of the plasma column forces a corresponding charge separation (consistent with quasi-neutrality) and a related electrostatic field. The ensuing electrostatic drift velocity (nearly) coincides with the dynamo velocity field traditionally considered to sustain the configuration [Bonfiglio,Cappello,Escande PRL 2005; Cappello,Bonfiglio,Escande PHP 2006]. In this presentation we review our present understanding in this subject. In particular we focus on the description of the formation of pure helical laminar RFP solutions, and study the relationship between the electrostatic structure and the topological properties of the magnetic field in the case of the less regular turbulent solutions, where the robustness of a chain of magnetic islands isolating the chaotic core from the edge has been recently highlighted [Spizzo,Cappello, Cravotta, Escande, Predebon, Marrelli, Martin, White, PRL 2006].

  4. Reversed-field pinch fusion reactor

    SciTech Connect

    Hagenson, R.L.; Krakowski, R.A.

    1980-01-01

    A conceptual engineering design of a fusion reactor based on plasma confinement in a toroidal Reversed-Field Pinch (RFP) configuration is described. The plasma is ohmically ignited by toroidal plasma currents which also inherently provide the confining magnetic fields in a toroidal chamber having major and minor radii of 12.7 and 1.5 m, respectively. The DT plasma ignites in 2 to 3 s and undergoes a transient, unrefueled burn at 10 to 20 keV for approx. 20 s to give a DT burnup of approx. 50%. The 5-s dwell period between burn pulses for plasma quench and refueling allows steady-state operation of all thermal systems outside the first wall; no auxiliary thermal capacity is required. Tritium breeding occurs in a granular Li/sub 2/O blanket which is packed around an array of radially oriented water/steam coolant tubes. The slightly superheated steam emerging from this blanket directly drives a turbine that produces electrical power at an efficiency of 30%. A borated-water shield is located immediately outside the thermal blanket to protect the superconducting magnet coils. Both the superconducting poloidal and toroidal field coils are energized by homopolar motor/generators. Accounting for all major energy sinks yields a cost-optimized system with a recirculating power fraction of 0.17; the power output is 750 MWe(net).

  5. Theta Pinch Coil Design for SSX

    NASA Astrophysics Data System (ADS)

    Shrock, J. E.; Han, J.; Kaur, M.; Brown, M. R.; Schaffner, D. A.

    2016-10-01

    We present the essential physics and design parameters behind a theta pinch coil used on SSX. The coil is used as an accelerator to drive flux behind a Taylor plume traveling about 30 km/sec. Operating between 25 and 40 kV on a time scale < 10 μs , the design focuses on minimizing the quarter cycle rise time (π/2√{ LC }) of the coil while maintaining the necessary precautions for working at high voltage. Our design works with 1.1 and 3.3 μF capacitors and a maximum stored electrical energy of U =1/2 CV2 = 880 J (at the lower capacitance). This electrical energy is converted into kinetic energy in the plume. Each plume has a mass greater than 30 μg , giving an initial kinetic energy of at least 14 J . At perfect efficiency, the upper bound of the plume velocity will be 240 km/sec using the lower capacitance circuit. Work supported by DOE OFES and ARPA-E ALPHA programs.

  6. Pinch Me - I'm Fusing!

    SciTech Connect

    DERZON,MARK S.

    2000-07-19

    The process of combining nuclei (the protons and neutrons inside an atomic nucleus) together with a release of kinetic energy is called fusion. This process powers the Sun, it contributes to the world stockpile of weapons of mass destruction and may one day generate safe, clean electrical power. Understanding the intricacies of fusion power, promised for 50 years, ,is sometimes difficult because there are a number of ways of doing it. There is hot fusion, cold fusion and con-fusion. Hot fusion is what powers suns through the conversion of mass energy to kinetic energy. Cold fusion generates con-fusion and nobody really knows what it is. Honestly - this is true. There does seem to be something going on here; I just don't know what. Apparently some experimenters get energy out of a process many call cold fission but no one seems to know what it is, or how to do it reliably. It is not getting much attention from the mainline physics community. Even so, no one is generating electrical power for you and me with either method. In this article 1 will point out some basic features of the mainstream approaches taken to hot fusion power, as well as describe why z pinches are worth pursuing as a driver for a power reactor and may one day generate electrical power for mankind.

  7. Application of pinch-and-swell structure rheology gauge to determine rock paleo-rheological parameters in Taili, western Liaoning, NE China

    NASA Astrophysics Data System (ADS)

    Sun, Zhengquan; Zeng, Zuoxun; Wu, Linbo; Xu, Shaopeng; Yang, Shuang; Chen, Deli; Wang, Jianxiu

    2017-05-01

    New results, in combination with previously published ones, reveal that when the Stress Exponent of the Competent layer (SEC) ranges from 1 to 10 (1 < n < 10), Pinch-and-Swell structure Rheology Gauge (PSRG) can only be available under the condition that the Viscosity ratio between the Competent layer and its corresponding Matrix layer (VCM) is larger than 10. Therefore, we made the attempt to calculate the viscosity ratio of pinch-and-swell structure of competent layer to the related matrix and stress exponent. Based on this knowledge, we applied this gauge to calculate SECs and VCMs of eight types of pinch-and-swell structures, which are widely developed in the Taili area of the west Liaoning Province in China. Statistical analysis of the SEC resulted in intervals of four types of competent layers, that is, Medium-scale Granitic coarse-to-pegmatitic Veins, Small-scale Augen Granite aplite Veins, Small-scale Granite aplite Veins, and Small-scale Augen Quartz-K-feldspar veins, with intervals of [3.50, 4.63], [2.64, 4.29], [2.70, 3.51], and [2.50, 3.36] respectively. The preferred intervals of VCM of the five types of pinch-and-swell structures, Small-scale Augen Granite aplite Veins + Fine-grained Biotite-Hornblende-plagioclase Gneiss, Medium-scale Granitic coarse-to-pegmatitic Veins + Fine-grained Biotite-Hornblende-plagioclase Gneiss, Small-scale Augen Granite aplite Veins + medium-to-fine-grained granitic gneiss, Medium-scale Granitic coarse-to-pegmatitic Veins + medium-to-fine-grained granitic gneiss, and Small-scale Augen Granite aplite Veins + fine-grained biotite-plagioclase gneiss, are [19.98, 62.51], [15.90, 61.17], [26.72, 93.27], [22.21, 107.26], and [76.33, 309.39] respectively. The similarities between these calculated SEC statistical preferred intervals and the physical experimental results verify the validity of the PSRG. The competent layers of the pinch-and-swell structures were presented in this study as power-law flow with SEC values that

  8. Magnetic Field Measurements in Wire-Array Z-Pinches using Magneto-Optically Active Waveguides

    SciTech Connect

    Syed, Wasif; Blesener, Isaac; Hammer, David A.; Lipson, Michal

    2009-01-21

    Understanding the magnetic field topology in wire-array Z-pinches as a function of time is of great significance to understanding these high-energy density plasmas especially for their ultimate application to stockpile stewardship and inertial confinement fusion. We are developing techniques to measure magnetic fields as a function of space and time using Faraday rotation of a single longitudinal mode (SLM) laser through a magneto-optically active bulk waveguide (multicomponent terbium borate glass) placed adjacent to, or within, the wire array in 1 MA experiments. We have measured fields >10 T with 100 ns rise times outside of a wire-array for the entire duration of the current pulse and as much as {approx}2 T inside a wire-array for {approx}40 ns from the start of current. This is the first time that such rapidly varying and large fields have been measured using these materials. In a dense Z-pinch, these sensing devices may not survive for long but may provide the magnetic field at the position of the sensor that can be used to corroborate magnetic probes, with which we compare our results.

  9. Effects of Resistivity and Viscosity on m =0 Rise and Fall Time in the RFP

    NASA Astrophysics Data System (ADS)

    Futch, A. M.; Craig, D.; Hesse, R.; Jacobson, C. M.

    2016-10-01

    In the reversed field pinch (RFP), poloidal mode number m =0 fluctuations are driven in a sawtooth cycle via nonlinear coupling with unstable m =1 tearing modes. We explore how the rise and fall time of these m =0 fluctuations depends on resistivity and viscosity in visco-resistive MHD simulations using the DEBS code. Both the Lundquist number (S) and magnetic Prandtl number (Pr) affect the rise/fall time. Analysis of MST experimental data also shows that both the rise and fall times of the m =0 amplitude vary with S. The variation observed in experiment is consistent with simulation results for rise time, but shows some differences for fall time. Rise time is insensitive to the resistivity profile but depends slightly on the viscosity profile. Fall time is strongly correlated with the duration of the crash which depends on both resistivity and viscosity profiles. These results suggest that the rise and fall time of the m =0 modes at the sawtooth crash is not strongly influenced by the local resistivity near the resonant surface but instead is primarily determined by the overall dynamics of the entire sawtooth cycle. The role of viscosity is less clear though the edge viscosity affects the m =0 evolution more than the core. This work has been supported by the U.S.D.O.E.

  10. Electrostatic mode associated with the pinch velocity in reversed field pinch simulations

    SciTech Connect

    Delzanno, Gian Luca; Finn, John M.; Chacon, Luis

    2008-12-15

    The existence of a new phenomenon in reversed field pinch (RFP) simulations related to the equilibrium pinch flow is discussed. This behavior is due to the inward equilibrium flow, but is strongly affected by boundary conditions on the perturbed azimuthal flow. It is important to understand and control this mechanism in single helicity simulations of RFPs. This mechanism can be explained in terms of an electrostatic instability related to a mode which can occur in fluid dynamics. In a simple linear model, it is shown that the mode, which is related to the inward advection of angular momentum from the edge, can be stabilized by using homogeneous Dirichlet (no-slip) boundary conditions at the wall. Behavior due to this mode is present in nonlinear simulations with zero-viscous-stress boundary conditions on the tangential velocity at the wall and, even in the presence of the usual magnetohydrodynamic modes, this mode can dominate the nonlinear dynamics of the velocity. In nonlinear simulations with Dirichlet boundary conditions on the tangential velocity, behavior associated with this electrostatic mode is not observed.

  11. Electrostatic mode associated with the pinch velocity in reversed field pinch simulations

    SciTech Connect

    Delzanno, Gian Luca; Chacon, Luis; Finn, John M.

    2008-01-01

    The existence of a new phenomenon in reversed field pinch (RFP) simulations related to the equilibrium pinch flow is discussed. This behavior is due to the inward equilibrium flow, but is strongly affected by boundary conditions on the perturbed azimuthal flow. It is important to understand and control this mechanism in single helicity simulations of RFPs. This mechanism can be explained in terms of an electrostatic instability related to a mode which can occur in fluid dynamics. In a simple linear model, it is shown that the mode, which is related to the inward advection of angular momentum from the edge, can be stabilized by using homogeneous Dirichlet (no-slip) boundary conditions at the wall. Behavior due to this mode is present in nonlinear simulations with zero-viscous-stress boundary conditions on the tangential velocity at the wall and, even in the presence of the usual magnetohydrodynamic modes, this mode can dominate the nonlinear dynamics of the velocity. In nonlinear simulations with Dirichlet boundary conditions on the tangential velocity, behavior associated with this electrostatic mode is not observed.

  12. Viscosity of particle laden films

    NASA Astrophysics Data System (ADS)

    Timounay, Yousra; Rouyer, Florence

    2017-06-01

    We perform retraction experiments on soap films where large particles bridge the two interfaces. Local velocities are measured by PIV during the unstationnary regime. The velocity variation in time and space can be described by a continuous fluid model from which effective viscosity (shear and dilatational) of particulate films is measured. The 2D effective viscosity of particulate films η2D increases with particle surface fraction ϕ: at low ϕ, it tends to the interfacial dilatational viscosity of the liquid/air interfaces and it diverges at the critical particle surface fraction ϕc ≃ 0.84. Experimental data agree with classical viscosity laws of hard spheres suspensions adapted to the 2D geometry, assuming viscous dissipation resulting from the squeeze of the liquid/air interfaces between the particles. Finally, we show that the observed viscous dissipation in particulate films has to be considered to describe the edge velocity during a retraction experiment at large particle coverage.

  13. Viscosity Depressants for Coal Liquefaction

    NASA Technical Reports Server (NTRS)

    Kalfayan, S. H.

    1983-01-01

    Proposed process modification incorporates viscosity depressants to prevent coal from solidifying during liquefaction. Depressants reduce amount of heat needed to liquefy coal. Possible depressants are metallic soaps, such as stearate, and amides, such as stearamide and dimer acid amides.

  14. Viscosity Depressants for Coal Liquefaction

    NASA Technical Reports Server (NTRS)

    Kalfayan, S. H.

    1983-01-01

    Proposed process modification incorporates viscosity depressants to prevent coal from solidifying during liquefaction. Depressants reduce amount of heat needed to liquefy coal. Possible depressants are metallic soaps, such as stearate, and amides, such as stearamide and dimer acid amides.

  15. Hydrodynamic Viscosity in Accretion Disks

    NASA Astrophysics Data System (ADS)

    Duschl, Wolfgang J.; Strittmatter, Peter A.; Biermann, Peter L.

    We propose a generalized accretion disk viscosity prescription based on hydrodynamically driven turbulence at the critical effective Reynolds number. This approach is consistent with recent re-analysis by Richard & Zahn (1999) of experimental results on turbulent Couette-Taylor flows. This new β-viscosity formulation applies to both selfgravitating and non-selfgravitating disks and is shown to yield the standard α-disk prescription in the case of shock dissipation limited, non-selfgravitating disks.

  16. Multicenter Survey of the Effects of Rehabilitation Practices on Pinch Force Strength After Tendon Transfer to Restore Pinch in Tetraplegia.

    PubMed

    Johanson, M Elise; Jaramillo, Jeffrey P; Dairaghi, Christine A; Murray, Wendy M; Hentz, Vincent R

    2016-06-01

    To identify key components of conventional therapy after brachioradialis (BR) to flexor pollicis longus (FPL) transfer, a common procedure to restore pinch strength, and evaluate whether any of the key components of therapy were associated with pinch strength outcomes. Rehabilitation protocols were surveyed in 7 spinal cord injury (SCI) centers after BR to FPL tendon transfer. Key components of therapy, including duration of immobilization, participation, and date of initiating therapy activities (mobilization, strengthening, muscle reeducation, functional activities, and home exercise), were recorded by the patient's therapist. Pinch outcomes were recorded with identical equipment at 1-year follow-up. Seven SCI rehabilitation centers where the BR to FPL surgery is performed on a routine basis. Thirty-eight arms from individuals with C5-7 level SCI injury who underwent BR to FPL transfer surgery (N=34). Conventional therapy according to established protocol in each center. The frequency of specific activities and their time of initiation (relative to surgery) were expressed as means and 95% confidence intervals. Outcome measures included pinch strength and the Canadian Occupational Performance Measure (COPM). Spearman rank-order correlations determined significant relations between pinch strength and components of therapy. There was similarity in the key components of therapy and in the progression of activities. Early cast removal was associated with pinch force (Spearman ρ=-.40, P=.0269). Pinch force was associated with improved COPM performance (Spearman ρ=.48, P=.0048) and satisfaction (Spearman ρ=.45, P=.0083) scores. Initiating therapy early after surgery is beneficial after BR to FPL surgery. Postoperative therapy protocols have the potential to significantly influence the outcome of tendon transfers after tetraplegia. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  17. Scaling of X pinches from 1 MA to 6 MA.

    SciTech Connect

    Bland, Simon Nicholas; McBride, Ryan D.; Wenger, David Franklin; Sinars, Daniel Brian; Chittenden, Jeremy Paul; Pikuz, Sergei A.; Harding, Eric; Jennings, Christopher A.; Ampleford, David J.; Yu, Edmund P.; Cuneo, Michael Edward; Shelkovenko, Tatiana A.; Hansen, Stephanie B.

    2010-09-01

    This final report for Project 117863 summarizes progress made toward understanding how X-pinch load designs scale to high currents. The X-pinch load geometry was conceived in 1982 as a method to study the formation and properties of bright x-ray spots in z-pinch plasmas. X-pinch plasmas driven by 0.2 MA currents were found to have source sizes of 1 micron, temperatures >1 keV, lifetimes of 10-100 ps, and densities >0.1 times solid density. These conditions are believed to result from the direct magnetic compression of matter. Physical models that capture the behavior of 0.2 MA X pinches predict more extreme parameters at currents >1 MA. This project developed load designs for up to 6 MA on the SATURN facility and attempted to measure the resulting plasma parameters. Source sizes of 5-8 microns were observed in some cases along with evidence for high temperatures (several keV) and short time durations (<500 ps).

  18. Rich Pinch: Perception of Object Movement with Tactile Illusion.

    PubMed

    Lee, Jaedong; Kim, Youngsun; Kim, Gerard

    2015-09-01

    Vibrotactile feedback is an effective and economical approach for enriching interactive feedback. However, its effects are mostly limited to providing supplementary alarms or conveying the sense of simple object presence or contact. In this paper, we propose a novel tactile feedback method, called Rich Pinch, based on the "out of body" tactile illusion for selecting and manipulating a virtual object using a two-finger pinch gesture. Rich Pinch uses vibration motors attached only to the two fingertips, but can induce illusory feedback, such as tactile touch/contact and directional movement, as felt from the space between the fingers. We first experimentally verify that the "out of body" illusion technique does in fact exist when applied between the fingertips. Then we compare three different tactile rendering functions to illustrate different resulting perceptual scales and argue to use the tangent-based interpolation in its actual application for a better user performance and experience due to its near-linear perceptual response. Finally, we assess the user experience (focusing on the perception of the object movement of the selected object) of the proposed pinch method by comparing it to the conventional contact-based method. Our results indicate that, with Rich Pinch, users were able to perceive rich dynamic feedback, and clearly preferred it over the conventional method.

  19. X-Pinch in High-Current Diode

    NASA Astrophysics Data System (ADS)

    Bryunetkin, B. A.; Faenov, A. Ya.; Ivanenkov, G. V.; Khakhalin, S. Ya.; Mingaleev, A. R.; Pikuz, S. A.; Romanova, V. M.; Shelkovenko, T. A.; Skobelev, I. Yu.

    1994-03-01

    The review of X-pinch investigations in high current diode of BIN facility (250 kA, 100 ns) is presented. The main purposes were to investigate pinch forming processes and hot dense plasma properties. X-pinch is also considered as a source for multiple charged ions spectroscopy and for X-ray optics testing. The set of diagnostics applied in these experiments allowed us to investigate the pinch forming processes in different configurations of crossed wires loads. High spectral and space resolved measurements of plasma radiation in 1-200 Å range, absolute energy measurements and electron beam registration were provided. Plasma parameters were obtained from relative intensities and shapes of multiple charged ions spectral lines. Electron density of plasma with the temperature Te = 0.2-1 keV variated from 1023 cm-3 in hot spot to 1018 cm-3 during plasma expansion. In recombining plasma, an inversion of Al He-like ions levels population was registrated. Total radiation output of 0.5 mm pinch reached hundreds Joules in 2-100 Å range during 100 ns.

  20. Ultrafast imaging method to measure surface tension and viscosity of inkjet-printed droplets in flight

    NASA Astrophysics Data System (ADS)

    Staat, Hendrik J. J.; van der Bos, Arjan; van den Berg, Marc; Reinten, Hans; Wijshoff, Herman; Versluis, Michel; Lohse, Detlef

    2017-01-01

    In modern drop-on-demand inkjet printing, the jetted droplets contain a mixture of solvents, pigments and surfactants. In order to accurately control the droplet formation process, its in-flight dynamics, and deposition characteristics upon impact at the underlying substrate, it is key to quantify the instantaneous liquid properties of the droplets during the entire inkjet-printing process. An analysis of shape oscillation dynamics is known to give direct information of the local liquid properties of millimeter-sized droplets and bubbles. Here, we apply this technique to measure the surface tension and viscosity of micrometer-sized inkjet droplets in flight by recording the droplet shape oscillations microseconds after pinch-off from the nozzle. From the damped oscillation amplitude and frequency we deduce the viscosity and surface tension, respectively. With this ultrafast imaging method, we study the role of surfactants in freshly made inkjet droplets in flight and compare to complementary techniques for dynamic surface tension measurements.

  1. X-pinch dynamics: Neck formation and implosion

    SciTech Connect

    Oreshkin, V. I.; Chaikovsky, S. A.; Artyomov, A. P.; Labetskaya, N. A.; Fedunin, A. V.; Rousskikh, A. G.; Zhigalin, A. S.

    2014-10-15

    We propose a model that describes the neck formation and implosion in an X-pinch. The process is simulated to go in two stages. The first stage is neck formation. This stage begins with an electrical explosion of the wires forming the X-pinch, and at the end of the stage, a micropinch (neck) is formed in the region where the wires are crossed. The second stage is neck implosion. The implosion is accompanied by outflow of matter from the neck region, resulting in the formation of a “hot spot”. Analytical estimates obtained in the study under consideration indicate that these stages are approximately equal in duration. Having analyzed the neck implosion dynamics, we have verified a scaling which makes it possible to explain the observed dependences of the time of occurrence of an x-ray pulse on the X-pinch current and mass.

  2. Resolving microstructures in Z pinches with intensity interferometry

    SciTech Connect

    Apruzese, J. P.; Kroupp, E.; Maron, Y.; Giuliani, J. L.; Thornhill, J. W.

    2014-03-15

    Nearly 60 years ago, Hanbury Brown and Twiss [R. Hanbury Brown and R. Q. Twiss, Nature 178, 1046 (1956)] succeeded in measuring the 30 nrad angular diameter of Sirius using a new type of interferometry that exploited the interference of photons independently emitted from different regions of the stellar disk. Its basis was the measurement of intensity correlations as a function of detector spacing, with no beam splitting or preservation of phase information needed. Applied to Z pinches, X pinches, or laser-produced plasmas, this method could potentially provide spatial resolution under one micron. A quantitative analysis based on the work of Purcell [E. M. Purcell, Nature 178, 1449 (1956)] reveals that obtaining adequate statistics from x-ray interferometry of a Z-pinch microstructure would require using the highest-current generators available. However, using visible light interferometry would reduce the needed photon count and could enable its use on sub-MA machines.

  3. Approach to universality in axisymmetric bubble pinch-off

    NASA Astrophysics Data System (ADS)

    Gekle, Stephan; Snoeijer, Jacco H.; Lohse, Detlef; van der Meer, Devaraj

    2009-09-01

    The pinch-off of an axisymmetric air bubble surrounded by an inviscid fluid is compared in four physical realizations: (i) cavity collapse in the wake of an impacting disk, (ii) gas bubbles injected through a small orifice, (iii) bubble rupture in a straining flow, and (iv) a bubble with an initially necked shape. Our boundary-integral simulations suggest that all systems eventually follow the universal behavior characterized by slowly varying exponents predicted by J. Eggers [Phys. Rev. Lett. 98, 094502 (2007)]. However, the time scale for the onset of this final regime is found to vary by orders of magnitude depending on the system in question. While for the impacting disk it is well in the millisecond range, for the gas injection needle universal behavior sets in only a few microseconds before pinch-off. These findings reconcile the different views expressed in recent literature about the universal nature of bubble pinch-off.

  4. Dielectric elastomer fingers for versatile grasping and nimble pinching

    NASA Astrophysics Data System (ADS)

    Lau, Gih-Keong; Heng, Kim-Rui; Ahmed, Anansa S.; Shrestha, Milan

    2017-05-01

    Boneless soft robotic fingers cannot apply concentrated forces to pinch a delicate object. This letter reports a three-dimensional design of dielectric elastomer fingers with higher flexural stiffness and close to 90° voltage-controllable bending for object gripping and pinching. It makes use of tension arch flexures to elevate a pre-stretched dielectric elastomer actuator (DEA) into a roof shape and thus magnifies the tension-induced moment, 40 times higher than a flat DEA does, to bend a stiff base frame. Such fingers make normally close-grippers to lift a payload 8-9 times their weight. They also make normally open grippers that pinch a highly deformable raw egg yolk.

  5. Pinch modes produced in the SPEED2 plasma focus

    NASA Astrophysics Data System (ADS)

    Kies, W.; Decker, G.; Berntien, U.; Sidelnikov, Yu V.; Glushkov, D. A.; Koshelev, K. N.; Simanovskii, D. M.; Bobashev, S. V.

    2000-08-01

    Deuterium discharges in the SPEED2 plasma focus doped with heavy gases (e.g. neon, argon) produce two pinch modes, the micropinch mode (MPM) or the stable column mode (SCM), with a transition regime where the initial SCM is followed by the MPM. Micropinches are local radiative collapses initiated by instabilities (m = 0 type) of low-energy-density pinch plasmas. These instabilities and the successive micropinches can be suppressed by kinetic deuterons produced during dynamical compression of high-energy-density deuterium plasma sheaths. Depending on the relaxation of this fast deuteron component the pinch column can be stabilized for several tens of nanoseconds. The SCM optimized with respect to the compression ratio is a powerful linear radiation source of high density (up to 1027 m-3) and temperature (up to 1 keV).

  6. MHD Simulation of the Inverse Pinch Plasma Discharge

    SciTech Connect

    Esaulov, A; Bauer, B; Lindemuth, I; Makhin, V; Presura, R; Ryutov, D

    2004-07-01

    A wall confined plasma in an inverse pinch configuration holds potential as a plasma target for Magnetized Target Fusion (MTF) as well as the simple geometry to study wall-confined plasma. An experiment is planned to study the inverse pinch configuration using the Nevada Terawatt Facility (NTF) at the University of Nevada, Reno (UNR). The dynamics of the discharge formation have been analyzed using analytic models and numerical methods. Strong heating occurs by thermalization of directed energy when an outward moving current sheet (the inverse pinch effect) collides with the outer wall of the experimental chamber. Two dimensional MHD simulations show Rayleigh-Taylor and Richtmyer-Meshkov -like modes of instability, as expected because of the shock acceleration during plasma formation phase. The instabilities are not disruptive, but give rise to a mild level of turbulence. The conclusion from this work is that an interesting experiment relevant to wall confinement for MTF could be done using existing equipment at UNR.

  7. Experiments and modelling of active quasi-single helicity regime generation in a reversed field pinch

    NASA Astrophysics Data System (ADS)

    Frassinetti, L.; Brunsell, P. R.; Drake, J. R.

    2009-07-01

    The interaction of a static resonant magnetic perturbation (RMP) with a tearing mode (TM) is becoming a relevant topic in fusion plasma physics. RMPs can be generated by active coils and then used to affect the properties of TMs and of the corresponding magnetic islands. This paper shows how the feedback system of the EXTRAP T2R reversed field pinch (RFP) can produce a RMP that affects a rotating TM and stimulate the transition to the so-called quasi-single helicity (QSH) regime, a RFP plasma state characterized by a magnetic island surrounded by low magnetic chaos. The application of the RMP can increase the QSH probability up to 10% and enlarge the size of the corresponding island. Part of the experimental results are supported by a theoretical study that models the effect of the active coils on the magnetic island.

  8. Energetic-Particle-Driven Instabilities and Their Effect on Fast Ions in a Reversed Field Pinch

    NASA Astrophysics Data System (ADS)

    Lin, L.; Ding, W. X.; Brower, D. L.; Koliner, J. J.; Eilerman, S.; Reusch, J.; Anderson, J. K.; Almagri, A. F.; Chapman, B. E.; Nornberg, M. D.; Sarff, J. S.; Waksman, J.; Liu, D.

    2012-10-01

    During 1 MW tangential neutral-beam injection (NBI) into the MST reversed field pinch, multiple, bursty instabilities (n=5, 4 and -1) are detected by various fluctuation diagnostics. The spatial structure of associated density fluctuations peaks near the core where fast ions reside. Significant bicoherence among them is measured, indicating nonlinear three-wave coupling. These instabilities are also observed by a laser-based Faraday-rotation diagnostic, containing critical information on the internal magnetic field fluctuations. A tangential-view high-energy neutral particle analyzer (NPA) is used to study the fast-ion population. The measured NPA signal decreases by 15% following NBI-driven instabilities, indicating fluctuation-induced fast-ion transport. The NBI also reduces the amplitude of the innermost-resonant tearing mode by up to 65%. This mode-suppression is lessened following the NBI-driven bursts, consistent with fast ion loss/redistribution weakening the suppression effect.

  9. Deoxyribonucleoside-modified squaraines as near-IR viscosity sensors.

    PubMed

    Zhang, Yuanwei; Yue, Xiling; Kim, Bosung; Yao, Sheng; Belfield, Kevin D

    2014-06-10

    Deoxyribonucleoside-modified squaraines were synthesized by Sonogashira coupling reactions using an unsymmetrical, terminal alkynylated benzothiazolium squaraine dye. These non-natural nucleosides exhibited fluorescent 'turn-on' properties in viscous conditions with an enhancement of >300-fold. The viscosity-dependent fluorescence enhancement was attributed to a combination of hampering both molecular aggregation and intramolecular bond rotation of the squaraine probe. Fluorescence microscopy allowed visualization of highly viscous regions during various stages of cellular mitosis.

  10. Transient flow and heating characteristics in a pinched plasma column.

    NASA Technical Reports Server (NTRS)

    York, T. M.; Stover, E. K.

    1972-01-01

    The generation of axial flow and heating of an argon plasma in a pinched plasma column of a pulsed, linear z-pinch device was examined experimentally and analytically. Transient (about 5 microsec) axial pressure profiles identify three characteristic periods in the column history. These include (1) strong axial pressure asymmetry indicative of plasma streaming, (2) isotropic, rapidly rising plasma pressure indicative of plasma heating, and (3) column breakup. An efficient conversion of radial collapse to axial streaming velocity is identified. Mechanisms for such an effect and subsequent heating are evaluated; significance to transients in pulsed plasma accelerators is identified.

  11. Reversed field pinch current drive with oscillating helical fields

    SciTech Connect

    Farengo, Ricardo; Clemente, Roberto Antonio

    2006-04-15

    The use of oscillating helical magnetic fields to produce and sustain the toroidal and poloidal currents in a reversed field pinch (RFP) is investigated. A simple physical model that assumes fixed ions, massless electrons, and uniform density and resistivity is employed. Thermal effects are neglected in Ohm's law and helical coordinates are introduced to reduce the number of coupled nonlinear equations that must be advanced in time. The results show that it is possible to produce RFP-like magnetic field profiles with pinch parameters close to the experimental values. The efficiencies obtained for moderate resistivity, and the observed scaling, indicate that this could be a very attractive method for high temperature plasmas.

  12. A compact, coaxial shunt current diagnostic for X pinches.

    PubMed

    Wang, Liangping; Zhang, Jinhai; Li, Mo; Zhang, Xinjun; Zhao, Chen; Zhang, Shaoguo

    2015-08-01

    A compact coaxial shunt was applied in X-pinches experiments on Qiangguang pulsed power generator. The coaxial shunt was designed to have a compact construction for smaller inductance and more, for conveniently assembling upon the X pinch load structure. The coaxial shunt is also a cheap current probe and was easily built by research groups. The shunt can monitor a 100 kA high current with a 100 ns rise time. The calibration results showed that the probe used in the experiments has a resistance of 3.2 mΩ with an uncertainty of 3%, and its response time to the step signal is less than 7 ns.

  13. Polycrystalline diamond based detector for Z-pinch plasma diagnosis.

    PubMed

    Liu, Linyue; Ouyang, Xiaoping; Zhao, Jizhen; Chen, Liang; Wang, Lan

    2010-08-01

    A detector setup based on polycrystalline chemical-vapor-deposition diamond film is developed with great characteristics: low dark current (lower than 60 pA within 3 V/mum), fast pulsed response time (rise time: 2-3 ns), flat spectral response (3-5 keV), easy acquisition, low cost, and relative large sensitive area. The characterizing data on Qiangguang-I accelerator show that this detector can satisfy the practical requirements in Z-pinch plasma diagnosis very well, which offers a promising prototype for the x-ray detection in Z-pinch diagnosis.

  14. Seeded perturbations in wire array Z-Pinches.

    SciTech Connect

    Robinson, Allen Conrad; Fedin, Dmitry; Kantsyrev, Victor Leonidovich; Wunsch, Scott Edward; Oliver, Bryan Velten; Lebedev, Sergey V.; Coverdale, Christine Anne; Ouart, Nicholas D.; LePell, Paul David; Safronova, Alla S.; Shrestha, I.; McKenney, John Lee; Ampleford, David J.; Rapley, J.; Bott, S. C.; Palmer, J. B. A.; Sotnikov, Vladimir Isaakovich; Bland, Simon Nicholas; Ivanov, Vladimir V.; Chittenden, Jeremy Paul; Jones, B.; Garasi, Christopher Joseph; Hall, Gareth Neville; Yilmaz, M. Faith; Mehlhorn, Thomas Alan; Deeney, Christopher; Pokala, S.; Nalajala, V.

    2005-07-01

    Controlled seeding of perturbations is employed to study the evolution of wire array z-pinch implosion instabilities which strongly impact x-ray production when the 3D plasma stagnates on axis. Wires modulated in radius exhibit locally enhanced magnetic field and imploding bubble formation at discontinuities in wire radius due to the perturbed current path. Wires coated with localized spectroscopic dopants are used to track turbulent material flow. Experiments and MHD modeling offer insight into the behavior of z-pinch instabilities.

  15. ELECTROSTATIC MODE ASSOCIATED WITH PINCH VELOCITY IN RFPS

    SciTech Connect

    DELZANNO, GIAN LUCA; FINN, JOHN M.; CHACON, LUIS

    2007-02-08

    The existence of a new electrostatic instability is shown for RFP (reversed field pinch) equilibria. This mode arises due to the non-zero equilibrium radial flow (pinch flow). In RFP simulations with no-stress boundary conditions on the tangential velocity at the radial wall, this electrostatic mode is unstable and dominates the nonlinear dynamics, even in the presence of the MHD modes typically responsible for the reversal of the axial magnetic field at edge. Nonlinearly, this mode leads to two beams moving azimuthally towards each other, which eventually collide. The electrostatic mode can be controlled by using Dirichlet (no-slip) boundary conditions on the azimuthal velocity at the radial wall.

  16. {alpha} Heating in a Stagnated Z-pinch

    SciTech Connect

    Appelbe, Brian; Chittenden, Jeremy

    2009-01-21

    A computational investigation of a scheme for magneto-inertial confinement fusion in a Z-pinch is carried out. In the scheme implosion of a deuterium-tritium fuel mass is preceded by formation of a hotspot containing warm, dense plasma on axis. The presence of the hotspot increases energy yield. Compression of the hotspot by the main fuel mass initiates thermonuclear burn. There is significant heating of the plasma by thermonuclear {alpha} particles which are confined by the strong magnetic field of the Z-pinch.

  17. The Viscosity-Temperature-Dependence of Liquids,

    DTIC Science & Technology

    The viscosity-temperature- dependence of liquids of different types can be represented by the formula lg kinematic viscosity = A/T to the x power + B...if A has a constant value, only one viscosity measurement at one temperature is necessary for the characterization of the viscosity-temperature- dependence . Examples for each different case are given. (Author)

  18. Viscosities of aqueous blended amines

    SciTech Connect

    Hsu, C.H.; Li, M.H.

    1997-07-01

    Solutions of alkanolamines are an industrially important class of compounds used in the natural gas, oil refineries, petroleum chemical plants, and synthetic ammonia industries for the removal of acidic components like CO{sub 2} and H{sub 2}S from gas streams. The viscosities of aqueous mixtures of diethanolamine (DEA) + N-methyldiethanolamine (MDEA), DEA + 2-amino-2-methyl-1-propanol (AMP), and monoethanolamine (MEA) + 2-piperidineethanol (2-PE) were measured from 30 C to 80 C. A Redlich-Kister equation for the viscosity deviation was applied to represent the viscosity. On the basis of the available viscosity data for five ternary systems, MEA + MDEA + H{sub 2}O, MEA + AMP + H{sub 2}O, DEA + MDEA + H{sub 2}O, DEA + AMP + H{sub 2}O, and MEA + 2-PE + H{sub 2}O, a generalized set of binary parameters were determined. For the viscosity calculation of the systems tested, the overall average absolute percent deviation is about 1.0% for a total of 499 data points.

  19. Viscosity-dependent protein dynamics.

    PubMed

    Finkelstein, Ilya J; Massari, Aaron M; Fayer, M D

    2007-05-15

    Spectrally resolved stimulated vibrational echo spectroscopy is used to investigate the dependence of fast protein dynamics on bulk solution viscosity at room temperature in four heme proteins: hemoglobin, myoglobin, a myoglobin mutant with the distal histidine replaced by a valine (H64V), and a cytochrome c552 mutant with the distal methionine replaced by an alanine (M61A). Fructose is added to increase the viscosity of the aqueous protein solutions over many orders of magnitude. The fast dynamics of the four globular proteins were found to be sensitive to solution viscosity and asymptotically approached the dynamical behavior that was previously observed in room temperature sugar glasses. The viscosity-dependent protein dynamics are analyzed in the context of a viscoelastic relaxation model that treats the protein as a deformable breathing sphere. The viscoelastic model is in qualitative agreement with the experimental data but does not capture sufficient system detail to offer a quantitative description of the underlying fluctuation amplitudes and relaxation rates. A calibration method based on the near-infrared spectrum of water overtones was constructed to accurately determine the viscosity of small volumes of protein solutions.

  20. Viscosity of liquid undercooled tungsten

    NASA Astrophysics Data System (ADS)

    Paradis, Paul-François; Ishikawa, Takehiko; Yoda, Shinichi

    2005-05-01

    Knowledge of the viscosity and its temperature dependence is essential to improve metallurgical processes as well as to validate theoretical and empirical models of liquid metals. However, data for metals with melting points above 2504K could not be determined yet due to contamination and containment problems. Here we report the viscosity of tungsten, the highest melting point metal (3695K), measured by a levitation technique. Over the 3350-3700-K temperature range, which includes the undercooled region by 345K, the viscosity data could be fitted as η(T )=0.108exp[1.28×105/(RT)](mPas). At the melting point, the datum agrees with the proposed theoretical and empirical models of liquid metals but presents atypical temperature dependence, suggesting a basic change in the mechanism of momentum transfer.

  1. Interinstrument reliability of the Jamar electronic dynamometer and pinch gauge compared with the Jamar hydraulic dynamometer and B&L Engineering mechanical pinch gauge.

    PubMed

    King, Theodore I

    2013-01-01

    OBJECTIVE. This study sought to determine interinstrument reliability of the Jamar electronic dynamometer and pinch gauge compared with the commonly used Jamar hydraulic dynamometer and B&L Engineering mechanical pinch gauge. METHOD. Twenty men and 20 women were tested for grip strength with the two different dynamometers, and 17 men and 25 women were tested for lateral pinch strength with the two different pinch gauges. RESULTS. Grip strength measurements were approximately 10% higher with the hydraulic dynamometer, and lateral pinch strength measurements were approximately 18% higher with the mechanical pinch gauge. Paired t tests and intraclass correlation coefficients (ICCs) were used for statistical analyses. The two-tailed p value was <.0001, and the ICC indicated poor to moderate reliability. CONCLUSION. When retesting patients, it is recommended that occupational therapists use the same instrument to measure hand strength because interinstrument reliability may be lacking.

  2. Hypoxic viscosity and diabetic retinopathy.

    PubMed Central

    Rimmer, T; Fleming, J; Kohner, E M

    1990-01-01

    Diabetic and sickle retinopathy have features in common--for example, venous dilatation, microaneurysms, and capillary closure preceding neovascularisation. Bearing in mind that haemoglobin in poorly controlled diabetes is abnormal and that extremely low oxygen tensions (known to cause sickling) exist in the healthy cat retina, we wished to explore the possibility that diabetic blood, like that of sickle cell disease, may become more viscous when deoxygenated. To do this we measured whole blood viscosity, under oxygenated and deoxygenated conditions, of 23 normal persons, 23 diabetic patients without retinopathy, and 34 diabetic patients with retinopathy. The shear rate used was 230 s-1, which is similar to that thought to prevail in the major retinal veins. The viscosity of blood from normal persons, corrected for packed cell volume, did not change significantly on deoxygenation: mean 4.54 (SD 0.38) cps, versus, 4.57 (0.39) paired t test, p = 0.66. Similarly the blood from diabetics without retinopathy showed no change: 4.42 (0.45) versus 4.42 (0.30), p = 0.98; whereas the blood from patients with retinopathy changed from 4.82 (0.48) to 4.95 (0.63), p = 0.027. The hypoxic viscosity ratio (deoxygenated divided by oxygenated viscosity) correlated with total serum cholesterol (r = 0.44, p = 0.018) but not with HbA1, serum glucose, triglycerides, or age. A disproportionate increase in venous viscosity relative to arterial viscosity would lead to increased intraluminal and transmural pressure and therefore exacerbate leakage across capillary walls. PMID:2378855

  3. Hypoxic viscosity and diabetic retinopathy.

    PubMed

    Rimmer, T; Fleming, J; Kohner, E M

    1990-07-01

    Diabetic and sickle retinopathy have features in common--for example, venous dilatation, microaneurysms, and capillary closure preceding neovascularisation. Bearing in mind that haemoglobin in poorly controlled diabetes is abnormal and that extremely low oxygen tensions (known to cause sickling) exist in the healthy cat retina, we wished to explore the possibility that diabetic blood, like that of sickle cell disease, may become more viscous when deoxygenated. To do this we measured whole blood viscosity, under oxygenated and deoxygenated conditions, of 23 normal persons, 23 diabetic patients without retinopathy, and 34 diabetic patients with retinopathy. The shear rate used was 230 s-1, which is similar to that thought to prevail in the major retinal veins. The viscosity of blood from normal persons, corrected for packed cell volume, did not change significantly on deoxygenation: mean 4.54 (SD 0.38) cps, versus, 4.57 (0.39) paired t test, p = 0.66. Similarly the blood from diabetics without retinopathy showed no change: 4.42 (0.45) versus 4.42 (0.30), p = 0.98; whereas the blood from patients with retinopathy changed from 4.82 (0.48) to 4.95 (0.63), p = 0.027. The hypoxic viscosity ratio (deoxygenated divided by oxygenated viscosity) correlated with total serum cholesterol (r = 0.44, p = 0.018) but not with HbA1, serum glucose, triglycerides, or age. A disproportionate increase in venous viscosity relative to arterial viscosity would lead to increased intraluminal and transmural pressure and therefore exacerbate leakage across capillary walls.

  4. Viscosity measurements on clear liquids

    SciTech Connect

    Walker, D.D.

    1993-02-09

    During the ITP cold chemical testing program, the efficiency of the benzene strippers will be measured and evaluated. Since the stripping efficiency is partially dependent upon the dynamic viscosity of the liquid phase, this property must be measured on samples taken during the test program. A procedure to measure the dynamic viscosity of salt solutions was developed from standard American Society of Testing and materials (ASTM) methods. The SRS procedure differs from the ASTM procedure and, therefore, a test program was initiated to determine its accuracy and precision. The results of these statistically designed tests are reported elsewhere, but supporting information on the experimental procedures, standards, and equipment are given in this report.

  5. Rotating reactor studies

    NASA Technical Reports Server (NTRS)

    Roberts, Glyn O.

    1991-01-01

    Undesired gravitational effects such as convection or sedimentation in a fluid can sometimes be avoided or decreased by the use of a closed chamber uniformly rotated about a horizontal axis. In a previous study, the spiral orbits of a heavy or buoyant particle in a uniformly rotating fluid were determined. The particles move in circles, and spiral in or out under the combined effects of the centrifugal force and centrifugal buoyancy. A optimization problem for the rotation rate of a cylindrical reactor rotated about its axis and containing distributed particles was formulated and solved. Related studies in several areas are addressed. A computer program based on the analysis was upgraded by correcting some minor errors, adding a sophisticated screen-and-printer graphics capability and other output options, and by improving the automation. The design, performance, and analysis of a series of experiments with monodisperse polystyrene latex microspheres in water were supported to test the theory and its limitations. The theory was amply confirmed at high rotation rates. However, at low rotation rates (1 rpm or less) the assumption of uniform solid-body rotation of the fluid became invalid, and there were increasingly strong secondary motions driven by variations in the mean fluid density due to variations in the particle concentration. In these tests the increase in the mean fluid density due to the particles was of order 0.015 percent. To a first approximation, these flows are driven by the buoyancy in a thin crescent-shaped depleted layer on the descending side of the rotating reactor. This buoyancy distribution is balanced by viscosity near the walls, and by the Coriolis force in the interior. A full analysis is beyond the scope of this study. Secondary flows are likely to be stronger for buoyant particles, which spiral in towards the neutral point near the rotation axis under the influence of their centrifugal buoyancy. This is because the depleted layer is

  6. Turbulence driven particle pinch at the pedestal region in EAST

    NASA Astrophysics Data System (ADS)

    Yan, Ning; Xu, Sheng; Chen, Liang; Lan, Heng

    2015-11-01

    Existence of an anomalous inward particle flux in tokamak has been realized for a long time. Since particle transport up the density gradient particularly play a key role on the formation of edge pedestal in H-mode plasma, intensive efforts were made to identify the origin of particle pinch in tokamak. However, the mechanism of particle pinch is still a big challenge for plasma physics. In order to improve our understanding on inward particle pinch, turbulent transport have been investigated in boundary plasma with reciprocating Langmuir probe measurements on EAST. A broad turbulence is detected in pedestal after the L-H transition, which shows as fast (300kHz-500kHz) fluctuations in floating potential signals. It appears and gradually saturates after the dithering phase. The broad turbulence is ultimately terminated by the break out of ELMs. It is observed that most of the particle transport is outward directed before the emergence of broad turbulence. However, the particle transport is reversed to inward direction once the broad turbulence initializes in pedestal. Moreover, the edge pedestal starts to establish at the onset of the observed broad turbulence. It gradually stabilizes with the saturation of broad turbulence. During this period, the fluctuations and associated transport in the SOL are almost unaffected, which suggests a signature of particle pinch induced by the broad turbulence originating at the pedestal region. Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China

  7. Pathokinematics of precision pinch movement associated with carpal tunnel syndrome.

    PubMed

    Nataraj, Raviraj; Evans, Peter J; Seitz, William H; Li, Zong-Ming

    2014-06-01

    Carpal tunnel syndrome (CTS) can adversely affect fine motor control of the hand. Precision pinch between the thumb and index finger requires coordinated movements of these digits for reliable task performance. We examined the impairment upon precision pinch function affected by CTS during digit movement and digit contact. Eleven CTS subjects and 11 able-bodied (ABL) controls donned markers for motion capture of the thumb and index finger during precision pinch movement (PPM). Subjects were instructed to repetitively execute the PPM task, and performance was assessed by range of movement, variability of the movement trajectory, and precision of digit contact. The CTS group demonstrated shorter path-length of digit endpoints and greater variability in inter-pad distance and most joint angles across the PPM movement. Subjects with CTS also showed lack of precision in contact points on the digit-pads and relative orientation of the digits at contact. Carpal tunnel syndrome impairs the ability to perform precision pinch across the movement and at digit-contact. The findings may serve to identify deficits in manual dexterity for functional evaluation of CTS.

  8. X-rays from a microsecond X-pinch

    SciTech Connect

    Appartaim, R. K.

    2013-08-28

    The characteristics of x-rays emitted by X-pinches driven by discharging a current of ∼320 kA with a quarter period of 1 μs in crossed 25 μm wires have been investigated. The x-ray emissions are studied using filtered silicon photodiodes, diamond radiation detectors, and pinhole cameras. The results show that predominantly x-rays from the microsecond X-pinch tend to be emitted in two distinct sets of bursts. The first is predominantly “soft,” i.e., with photon energy hν < 5 keV, followed by a second set of bursts beginning up to 100 ns following the initial bursts, and usually consisting of higher photon energies. Our results show, however, that the x-ray emissions do not contain a significant component with hν > 10 keV as might be expected from electron beam activity within the plasma or from the X-pinch diode. High-resolution images obtained with the observed x-rays suggest a well-defined small source of soft x-rays that demonstrates the potential of the microsecond X-pinch.

  9. 9th International Conference on Dense Z-Pinches

    SciTech Connect

    Bott-Suzuki, Simon

    2015-08-31

    DOE OFES supported the 9th International Conference on Z-Pinches (DZP 2014) held in Napa, CA in August 2014. Funds were used to support travel for several US students, and to disseminate information through the publication of a proceedings volume.

  10. The Concept of the Pinch Helicon Magnetoplasma Thruster

    NASA Astrophysics Data System (ADS)

    Ribeiro, Celso

    2015-11-01

    A new concept of a high efficient electrodeless magnetoplasma-based electric thruster using a helicon plasma submitted to a pinch effect is proposed. This concept is intended to have high thrust for a short period, while reducing the plasma-wall contact. This proposal is highly suitable for rocket devices for faster satellites' orbital correction, a feasible way to lead manned missions into deep space, and for a more compact plasma sources for plasma materials for fusion studies. The pinch effect is created by a set of poloidal field coils placed around the insulating cylinder where the helical antenna is mounted. A pulsed current creates the pinch effect, which immediately insulates the plasma to the wall, thus reducing the perpendicular particle and energy losses. As a consequence, the axial flux, thus the thrust, should be increased because of particle balance. This may require an additional magnetic field produced by a single coil placed at the back of the helicon antenna (the gas entrance) to be acted during the pinch phase, leading to an unbalanced magnetic mirror-type configuration, therefore a net flux outwards. The combination with the double helicon structure may also maximize the efficiency. If everything is synchronized, there will be no gas or energy wasted, and the wall heat will be minimal, thus reducing the problems of material fatigue and failures, and making feasible the use of conventional materials.

  11. Linear Transformer Drivers for Z-pinch Based Propulsion

    NASA Technical Reports Server (NTRS)

    Adams, Robert; Seidler, William; Giddens, Patrick; Fabisinski, Leo; Cassibry, Jason

    2017-01-01

    The MSFC/UAH team has been developing of a novel power management and distribution system called a Linear Transformer Driver (LTD). LTD's hold the promise of dramatically reducing the required mass to drive a z-pinch by replacing the capacitor banks which constitute half the mass of the entire system. The MSFC?UAH tea, is developing this technology in hope of integrating it with the Pulsed Fission Fusion (PuFF) propulsion concept. High-Voltage pulsed power systems used for Z-Pinch experimentation have in the past largely been based on Marx Generators. Marx generators deliver the voltage and current required for the Z-Pinch, but suffer from two significant drawbacks when applied to a flight system: they are very massive, consisting of high-voltage capacitor banks insulated in oil-filled tanks and they do not lend themselves to rapid pulsing. The overall goal of Phase 2 is to demonstrate the construction of a higher voltage stack from a number of cavities each of the design proven in Phase 1 and to characterize and understand the techniques for designing the stack. The overall goal of Phase 3 is to demonstrate the feasibility of constructing a higher energy cavity from a number of smaller LTD stacks, to characterize and understand the way in which the constituent stacks combine, and to extend this demonstration LTD to serve as the basis for a 64 kJ pulse generator for Z-Pinch experiments.

  12. Pathokinematics of Precision Pinch Movement Associated with Carpal Tunnel Syndrome

    PubMed Central

    Nataraj, Raviraj; Evans, Peter J.; Seitz, William H.; Li, Zong-Ming

    2014-01-01

    Purpose Carpal tunnel syndrome (CTS) can adversely affect fine motor control of the hand. Precision pinch between the thumb and index finger requires coordinated movements of these digits for reliable task performance. This study examined the impairment upon precision pinch function affected by CTS during digit movement and digit contact. Methods Eleven CTS subjects and 11 able-bodied (ABL) controls donned markers for motion capture of the thumb and index finger during precision pinch movement (PPM). Subjects were instructed to repetitively execute the PPM task, and performance was assessed by range of movement, variability of the movement trajectory, and precision of digit contact. Results The CTS group demonstrated shorter path-length of digit endpoints and greater variability in inter-pad distance and most joint angles across the PPM movement. Subjects with CTS also showed lack of precision in contact points on the digit-pads and relative orientation of the digits at contact. Conclusions Carpal tunnel syndrome impairs the ability to perform precision pinch across the movement and at digit-contact. The findings may serve to identify deficits in manual dexterity for functional evaluation of CTS. PMID:24536036

  13. Pinch technique and the Batalin-Vilkovisky formalism

    NASA Astrophysics Data System (ADS)

    Binosi, Daniele; Papavassiliou, Joannis

    2002-07-01

    In this paper we take the first step towards a nondiagrammatic formulation of the pinch technique. In particular we proceed into a systematic identification of the parts of the one-loop and two-loop Feynman diagrams that are exchanged during the pinching process in terms of unphysical ghost Green's functions; the latter appear in the standard Slavnov-Taylor identity satisfied by the tree-level and one-loop three-gluon vertex. This identification allows for the consistent generalization of the intrinsic pinch technique to two loops, through the collective treatment of entire sets of diagrams, instead of the laborious algebraic manipulation of individual graphs, and sets up the stage for the generalization of the method to all orders. We show that the task of comparing the effective Green's functions obtained by the pinch technique with those computed in the background field method Feynman gauge is significantly facilitated when employing the powerful quantization framework of Batalin and Vilkovisky. This formalism allows for the derivation of a set of useful nonlinear identities, which express the background field method Green's functions in terms of the conventional (quantum) ones and auxiliary Green's functions involving the background source and the gluonic antifield; these latter Green's functions are subsequently related by means of a Schwinger-Dyson type of equation to the ghost Green's functions appearing in the aforementioned Slavnov-Taylor identity.

  14. Plasma Pinch for HIF Final Focus and Transport

    NASA Astrophysics Data System (ADS)

    Vella, M.; Fessenden, T.; Leemans, W.; Ponce, D.; Yu, S.

    1997-11-01

    A laser initiated, double pulse technique is used to create straight, stable Z-pinch channels with electronic timing reproducibility (10 nsec). A KrF laser designates the channel path. After a 20 μsec laser-resistor phase in the 7 T fill gas, a prepulse channel forms by avalanche breakdown. The prepulse channel heats a low density gas region that provides a preferred breakdown path for the high current discharge Z-pinch. After a delay to absorb the timing uncertainty of the prepulse channel, a stable high current Z-pinch is triggered. Earlier experiments(Ref. 1. Tauschwitz, S.S. Yu, S. Eylon, R.O. Bangerter, W. Leemans, C. Peters, J.O. Rasmussen, L. Teginato, J.J. Barnard and W.M. Sharp. Fusion Eng. and Design 32-33 (1996) 493-502.) at LBNL demonstrated narrow, stable 50 kA channels, which is more than enough for Heavy Ion Fusion (HIF) final focus and transport. We present interferometer and Schlieren studies of pinch density and small scale stability. Stable return current paths at 90^o to the high current channel are documented, and the implication for an HIF reactor scenario mentioned.

  15. The PINCH-ILK-parvin complexes: assembly, functions and regulation.

    PubMed

    Wu, Chuanyue

    2004-07-05

    Cell-extracellular matrix (ECM) adhesion is mediated by transmembrane cell adhesion receptors (e.g., integrins) and receptor proximal cytoplasmic proteins. Over the past several years, studies using biochemical, structural, cell biological and genetic approaches have provided important evidence suggesting crucial roles of integrin-linked kinase (ILK), PINCH and CH-ILKBP/actopaxin/affixin/parvin (abbreviated as parvin herein) in ECM control of cell behavior. One general theme emerging from these studies is that the formation of ternary protein complexes consisting of ILK, PINCH and parvin is pivotal to the functions of PINCH, ILK and parvin proteins. In addition, recent studies have begun to uncover the molecular mechanisms underlying the assembly, functions and regulation of the PINCH-ILK-parvin (PIP) complexes. The PIP complexes provide crucial physical linkages between integrins and the actin cytoskeleton and transduce diverse signals from ECM to intracellular effectors. Among the challenges of future studies are to define the functions of different PIP complexes in various cellular processes, identify additional partners of the PIP complexes that regulate and/or mediate the functions of the PIP complexes, and determine the roles of the PIP complexes in the pathogenesis of human diseases involving abnormal cell-ECM adhesion and signaling.

  16. Pinch-off Dynamics of Non-Newtonian Fluids

    NASA Astrophysics Data System (ADS)

    Huisman, F. M.; Gutman, S. R.; Taborek, P.

    2010-11-01

    The pinch-off dynamics of a variety of shear-thinning fluids (foams, concentrated emulsions, and slurries) were studied using high speed videography. The pinch was characterized by the variation of the minimum neck radius rmin as a function of the time to pinch t, with rmin prop to t^α. The rheology of shear thinning fluids can be characterized by an exponent τ = k γ^n, with n < 1. We found that for a variety of shear-thinning fluids including mayonnaise and acrylic paint, rmin scales with t to a power α equal to the flow index for the particular fluid. The flow index was measured using a TA instruments AR-G2 rheometer. The flow index for acrylic paint was 0.440 +/- 0.014 and rmin scales with t to the 0.41 +/- 0.03; for mayonnaise the flow index was 0.355 +/- 0.014; and rmin scales with t to the 0.35+/- 0.02. To study the transition from conventional Newtonian pinch, we systematically varied the concentration of a water-Xanthan gum mixture.

  17. Fluid viscosity under confined conditions

    NASA Astrophysics Data System (ADS)

    Rudyak, V. Ya.; Belkin, A. A.

    2014-12-01

    Closed equations of fluid transfer in confined conditions are constructed in this study using ab initio methods of nonequilibrium statistical mechanics. It is shown that the fluid viscosity is not determined by the fluid properties alone, but becomes a property of the "fluid-nanochannel walls" system as a whole. Relations for the tensor of stresses and the interphase force, which specifies the exchange by momentum of fluid molecules with the channel-wall molecules, are derived. It is shown that the coefficient of viscosity is now determined by the sum of three contributions. The first contribution coincides with the expression for the coefficient of the viscosity of fluid in the bulk being specified by the interaction of fluid molecules with each other. The second contribution has the same structure as the first one but is determined by the interaction of fluid molecules with the channel-wall molecules. Finally, the third contribution has no analog in the usual statistical mechanics of transport processes of a simple fluid. It is associated with the correlation of intermolecular forces of the fluid and the channel walls. Thus, it is established that the coefficient of viscosity of fluid in sufficiently small channels will substantially differ from its bulk value.

  18. Anomalous-viscosity current drive

    DOEpatents

    Stix, T.H.; Ono, M.

    1986-04-25

    The present invention relates to a method and apparatus for maintaining a steady-state current for magnetically confining the plasma in a toroidal magnetic confinement device using anomalous viscosity current drive. A second aspect of this invention relates to an apparatus and method for the start-up of a magnetically confined toroidal plasma.

  19. Role of PINCH and Its Partner Tumor Suppressor Rsu-1 in Regulating Liver Size and Tumorigenesis

    PubMed Central

    Donthamsetty, Shashikiran; Bhave, Vishakha S.; Mars, Wendy M.; Bowen, William C.; Orr, Anne; Haynes, Meagan M.; Wu, Chuanyue; Michalopoulos, George K.

    2013-01-01

    Particularly interesting new cysteine-histidine-rich protein (PINCH) protein is part of the ternary complex known as the IPP (integrin linked kinase (ILK)-PINCH-Parvin-α) complex. PINCH itself binds to ILK and to another protein known as Rsu-1 (Ras suppressor 1). We generated PINCH 1 and PINCH 2 Double knockout mice (referred as PINCH DKO mice). PINCH2 elimination was systemic whereas PINCH1 elimination was targeted to hepatocytes. The genetically modified mice were born normal. The mice were sacrificed at different ages after birth. Soon after birth, they developed abnormal hepatic histology characterized by disorderly hepatic plates, increased proliferation of hepatocytes and biliary cells and increased deposition of extracellular matrix. After a sustained and prolonged proliferation of all epithelial components, proliferation subsided and final liver weight by the end of 30 weeks in livers with PINCH DKO deficient hepatocytes was 40% larger than the control mice. The livers of the PINCH DKO mice were also very stiff due to increased ECM deposition throughout the liver, with no observed nodularity. Mice developed liver cancer by one year. These mice regenerated normally when subjected to 70% partial hepatectomy and did not show any termination defect. Ras suppressor 1 (Rsu-1) protein, the binding partner of PINCH is frequently deleted in human liver cancers. Rsu-1 expression is dramatically decreased in PINCH DKO mouse livers. Increased expression of Rsu-1 suppressed cell proliferation and migration in HCC cell lines. These changes were brought about not by affecting activation of Ras (as its name suggests) but by suppression of Ras downstream signaling via RhoGTPase proteins. In conclusion, our studies suggest that removal of PINCH results in enlargement of liver and tumorigenesis. Decreased levels of Rsu-1, a partner for PINCH and a protein often deleted in human liver cancer, may play an important role in the development of the observed phenotype. PMID

  20. Role of PINCH and its partner tumor suppressor Rsu-1 in regulating liver size and tumorigenesis.

    PubMed

    Donthamsetty, Shashikiran; Bhave, Vishakha S; Mars, Wendy M; Bowen, William C; Orr, Anne; Haynes, Meagan M; Wu, Chuanyue; Michalopoulos, George K

    2013-01-01

    Particularly interesting new cysteine-histidine-rich protein (PINCH) protein is part of the ternary complex known as the IPP (integrin linked kinase (ILK)-PINCH-Parvin-α) complex. PINCH itself binds to ILK and to another protein known as Rsu-1 (Ras suppressor 1). We generated PINCH 1 and PINCH 2 Double knockout mice (referred as PINCH DKO mice). PINCH2 elimination was systemic whereas PINCH1 elimination was targeted to hepatocytes. The genetically modified mice were born normal. The mice were sacrificed at different ages after birth. Soon after birth, they developed abnormal hepatic histology characterized by disorderly hepatic plates, increased proliferation of hepatocytes and biliary cells and increased deposition of extracellular matrix. After a sustained and prolonged proliferation of all epithelial components, proliferation subsided and final liver weight by the end of 30 weeks in livers with PINCH DKO deficient hepatocytes was 40% larger than the control mice. The livers of the PINCH DKO mice were also very stiff due to increased ECM deposition throughout the liver, with no observed nodularity. Mice developed liver cancer by one year. These mice regenerated normally when subjected to 70% partial hepatectomy and did not show any termination defect. Ras suppressor 1 (Rsu-1) protein, the binding partner of PINCH is frequently deleted in human liver cancers. Rsu-1 expression is dramatically decreased in PINCH DKO mouse livers. Increased expression of Rsu-1 suppressed cell proliferation and migration in HCC cell lines. These changes were brought about not by affecting activation of Ras (as its name suggests) but by suppression of Ras downstream signaling via RhoGTPase proteins. In conclusion, our studies suggest that removal of PINCH results in enlargement of liver and tumorigenesis. Decreased levels of Rsu-1, a partner for PINCH and a protein often deleted in human liver cancer, may play an important role in the development of the observed phenotype.

  1. Formation of a pinched electron beam and an intense x-ray source in radial foil rod-pinch diodes

    NASA Astrophysics Data System (ADS)

    Sorokin, S. A.

    2016-04-01

    Low-impedance rod-pinch diode experiments were performed on the MIG generator at Institute of High Current Electronics using an aluminum foil placed between concentric electrodes of a rod-pinch diode. The J × B force accelerates the foil plasma in the axial and radial directions. After the foil plasma is pushed beyond the tip of the rod, a vacuum gap and a pinched electron beam form. The anode and cathode plasmas expansion and the following plasmas sweeping up by the J × B force can result in repetitive gap formations and closures, which are evident in the several successive intense x-ray pulses. A 0.7-mm-size point-like x-ray source was realized using a 1-mm-diameter tungsten rod, tapered to a point over the last 10 mm. The results of experiments show that the foil-shorted rod-pinch diode configuration has the potential to form low-impedance diodes, to shorten x-ray pulse duration and to realize submillimeter spot-size x-ray sources.

  2. Formation of a pinched electron beam and an intense x-ray source in radial foil rod-pinch diodes

    SciTech Connect

    Sorokin, S. A.

    2016-04-15

    Low-impedance rod-pinch diode experiments were performed on the MIG generator at Institute of High Current Electronics using an aluminum foil placed between concentric electrodes of a rod-pinch diode. The J × B force accelerates the foil plasma in the axial and radial directions. After the foil plasma is pushed beyond the tip of the rod, a vacuum gap and a pinched electron beam form. The anode and cathode plasmas expansion and the following plasmas sweeping up by the J × B force can result in repetitive gap formations and closures, which are evident in the several successive intense x-ray pulses. A 0.7-mm-size point-like x-ray source was realized using a 1-mm-diameter tungsten rod, tapered to a point over the last 10 mm. The results of experiments show that the foil-shorted rod-pinch diode configuration has the potential to form low-impedance diodes, to shorten x-ray pulse duration and to realize submillimeter spot-size x-ray sources.

  3. Research on pinching characteristics of electron beams emitted from different cathode surfaces of a rod-pinch diode

    NASA Astrophysics Data System (ADS)

    Gao, Yi; Qiu, Aici; Zhang, Zhong; Zhang, Pengfei; Wang, Zhiguo; Yang, Hailiang

    2010-07-01

    The particle-in-cell code UNIPIC is used to simulate the working process of a rod-pinch diode and investigate the pinching characteristics of electron beams emitted from different cathode surfaces. The simulation results indicate that the electron beam emitted from the upstream surface pinches better than from other surfaces when all the three surfaces emit electrons. The charge-density deposition on the anode surface peaks at the rod tip while the deposited charge density is approximately uniform over the first 15 mm of the rod before rapidly increasing over the last 3 mm, indicating a large axial extent of electron deposition. For the case of single-surface emission, the pinching quality of the electron beam emitted from the downstream surface is better than those from other surfaces. The charge-density deposition peaks at the rod tip and decreases rapidly off the tip. Based on the relationship of Larmor radius, beam's self-magnetic field, and the spatial current distribution, the above simulation results are analyzed theoretically. The experiments are performed on the inductive voltage adder to examine the simulations. By comparing the axial distribution of the radiation on the anode rod measured with the pinhole camera and the on-axis forward x-ray dose measured with the LiF thermoluminescent detectors, the simulation results are verified. The electron emission suppression method and the impedance change for each case are investigated or discussed in this paper.

  4. Viscosity Relaxation in Molten HgZnTe

    NASA Technical Reports Server (NTRS)

    Su, Ching-Hua; Lehoczky, S. L.; Kim, Yeong Woo; Baird, James K.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Rotating cup measurements of the viscosity of the pseudo-binary melt, HgZnTe have shown that the isothermal liquid with zinc mole fraction 0.16 requires tens of hours of equilibration time before a steady viscous state can be achieved. Over this relaxation period, the viscosity at 790 C increases by a factor of two, while the viscosity at 810 C increases by 40%. Noting that the Group VI elements tend to polymerize when molten, we suggest that the viscosity of the melt is enhanced by the slow formation of Te atom chains. To explain the build-up of linear Te n-mers, we propose a scheme, which contains formation reactions with second order kinetics that increase the molecular weight, and decomposition reactions with first order kinetics that inactivate the chains. The resulting rate equations can be solved for the time dependence of each molecular weight fraction. Using these molecular weight fractions, we calculate the time dependence of the average molecular weight. Using the standard semi-empirical relation between polymer average molecular weight and viscosity, we then calculate the viscosity relaxation curve. By curve fitting, we find that the data imply that the rate constant for n-mer formation is much smaller than the rate constant for n-mer deactivation, suggesting that Te atoms only weakly polymerize in molten HgZnTe. The steady state toward which the melt relaxes occurs as the rate of formation of an n-mer becomes exactly balanced by the sum of the rate for its deactivation and the rate for its polymerization to form an (n+1)-mer.

  5. Effective viscosity of non-gravitactic Chlamydomonas Reinhardtii microswimmer suspensions

    NASA Astrophysics Data System (ADS)

    Mussler, Matthias; Rafaï, Salima; Peyla, Philippe; Wagner, Christian

    2013-03-01

    Active microswimmers are known to affect the macroscopic viscosity of suspensions in a more complex manner than passive particles. For puller-like microswimmers an increase in the viscosity has been observed. It has been suggested that the persistence of the orientation of the microswimmers hinders the rotation that is normally caused by the vorticity. It was previously shown that some sorts of algae are bottom-heavy swimmers, i.e., their centre of mass is not located in the centre of the body. In this way, the algae affect the vorticity of the flow when they are perpendicularly oriented to the axis of gravity. This orientation of gravity to vorticity is given in a rheometer that is equipped with a cone-plate geometry. Here we present measurements of the viscosity both in a cone-plate and a Taylor-Couette cell. The two set-ups yielded the same increase in viscosity although the axis of gravitation in the Taylor-Couette cell is parallel to the direction of vorticity. In a complementary experiment we tested the orientation of the direction of swimming through microscopic observation of single Chlamydomonas reinhardtii and could not identify a preferred orientation, i.e., our specific strain of Chlamydomonas reinhardtii are not bottom-heavy swimmers. We thus conclude that bottom heaviness is not a prerequisite for the increase of viscosity and that the effect of gravity on the rheology of our strain of Chlamydomonas reinhardtii is negligible. This finding reopens the question of whether the origin of persistence in the orientation of cells is actually responsible for the increased viscosity of the suspension.

  6. Viscosity Relaxation in Molten HgZnTe

    NASA Technical Reports Server (NTRS)

    Su, Ching-Hua; Lehoczky, S. L.; Kim, Yeong Woo; Baird, James K.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Rotating cup measurements of the viscosity of the pseudo-binary melt, HgZnTe have shown that the isothermal liquid with zinc mole fraction 0.16 requires tens of hours of equilibration time before a steady viscous state can be achieved. Over this relaxation period, the viscosity at 790 C increases by a factor of two, while the viscosity at 810 C increases by 40%. Noting that the Group VI elements tend to polymerize when molten, we suggest that the viscosity of the melt is enhanced by the slow formation of Te atom chains. To explain the build-up of linear Te n-mers, we propose a scheme, which contains formation reactions with second order kinetics that increase the molecular weight, and decomposition reactions with first order kinetics that inactivate the chains. The resulting rate equations can be solved for the time dependence of each molecular weight fraction. Using these molecular weight fractions, we calculate the time dependence of the average molecular weight. Using the standard semi-empirical relation between polymer average molecular weight and viscosity, we then calculate the viscosity relaxation curve. By curve fitting, we find that the data imply that the rate constant for n-mer formation is much smaller than the rate constant for n-mer deactivation, suggesting that Te atoms only weakly polymerize in molten HgZnTe. The steady state toward which the melt relaxes occurs as the rate of formation of an n-mer becomes exactly balanced by the sum of the rate for its deactivation and the rate for its polymerization to form an (n+1)-mer.

  7. Transport Studies in Reversed Field Theta Pinches.

    DTIC Science & Technology

    1980-09-25

    on the separatrix is not necessary for an accurate calculation of the decay rate of the equilibrium . 13 IV. AN011ALOUS ROTATION GENERATION In this...Drake, N. T. Gladd and J. D. Huba, submitted to Phys. Fluids (1980). 9. W. M. Manheimer, An Introduction to Trapped-Particle Instability in Tokamaks ...surfaces for a typical RFP equilibrium . The scale is compressed in the axial (z) direction. 25 -0.2- - w 1.00 Z -0.0 -4.0 -0.80-M 1.000 N 0.4.00 or 2.00 N

  8. High-resolution intracellular viscosity measurement using time-dependent fluorescence anisotropy.

    PubMed

    Parker, Wesley C; Chakraborty, Nilay; Vrikkis, Regina; Elliott, Gloria; Smith, Stuart; Moyer, Patrick J

    2010-08-02

    A low-cost pulsed laser is used in conjunction with a homebuilt laser confocal-scanning epifluorescence microscope having submicron lateral and axial spatial resolution to determine cytoplasmic viscosity at specific intracytoplasmic locations in J774 mouse macrophage cells. Time-dependent fluorescence anisotropy measurements are made at each location and global deconvolution techniques are used to determine rotational correlation times. These rotational correlation times are related to the hydrated volume of 8-hydroxyperene-1,3,6-trisulfonic acid (HPTS) to calculate viscosity at specific points inside the cell. In the cytoplasmic areas measured, rotational correlation times of HPTS ranged from 0.186 ns to 0.411 ns, corresponding to viscosities ranging from 1.00 +/- 0.03 cP to 2.21+/- 0.05 cP.

  9. Low viscosity in the aqueous domain of cell cytoplasm measured by picosecond polarization microfluorimetry

    PubMed Central

    1991-01-01

    Information about the rheological characteristics of the aqueous cytoplasm can be provided by analysis of the rotational motion of small polar molecules introduced into the cell. To determine fluid-phase cytoplasmic viscosity in intact cells, a polarization microscope was constructed for measurement of picosecond anisotropy decay of fluorescent probes in the cell cytoplasm. We found that the rotational correlation time (tc) of the probes, 2,7-bis-(2-carboxyethyl)-5-(and-6- )carboxyfluorescein (BCECF), 6-carboxyfluorescein, and 8-hydroxypyrene- 1,3,6-trisulfonic acid (HPTS) provided a direct measure of fluid-phase cytoplasmic viscosity that was independent of probe binding. In quiescent Swiss 3T3 fibroblasts, tc values were 20-40% longer than those in water, indicating that the fluid-phase cytoplasm is only 1.2- 1.4 times as viscous as water. The activation energy of fluid-phase cytoplasmic viscosity was 4 kcal/mol, which is similar to that of water. Fluid-phase cytoplasmic viscosity was altered by less than 10% upon addition of sucrose to decrease cell volume, cytochalasin B to disrupt cell cytoskeleton, and vasopressin to activate phospholipase C. Nucleoplasmic and peripheral cytoplasmic viscosities were not different. Our results establish a novel method to measure fluid-phase cytoplasmic viscosity, and indicate that fluid-phase cytoplasmic viscosity in fibroblasts is similar to that of free water. PMID:1993739

  10. Viscosity of deeply supercooled water and its coupling to molecular diffusion.

    PubMed

    Dehaoui, Amine; Issenmann, Bruno; Caupin, Frédéric

    2015-09-29

    The viscosity of a liquid measures its resistance to flow, with consequences for hydraulic machinery, locomotion of microorganisms, and flow of blood in vessels and sap in trees. Viscosity increases dramatically upon cooling, until dynamical arrest when a glassy state is reached. Water is a notoriously poor glassformer, and the supercooled liquid crystallizes easily, making the measurement of its viscosity a challenging task. Here we report viscosity of water supercooled close to the limit of homogeneous crystallization. Our values contradict earlier data. A single power law reproduces the 50-fold variation of viscosity up to the boiling point. Our results allow us to test the Stokes-Einstein and Stokes-Einstein-Debye relations that link viscosity, a macroscopic property, to the molecular translational and rotational diffusion, respectively. In molecular glassformers or liquid metals, the violation of the Stokes-Einstein relation signals the onset of spatially heterogeneous dynamics and collective motions. Although the viscosity of water strongly decouples from translational motion, a scaling with rotational motion remains, similar to canonical glassformers.

  11. Viscosity of deeply supercooled water and its coupling to molecular diffusion

    PubMed Central

    Dehaoui, Amine; Issenmann, Bruno; Caupin, Frédéric

    2015-01-01

    The viscosity of a liquid measures its resistance to flow, with consequences for hydraulic machinery, locomotion of microorganisms, and flow of blood in vessels and sap in trees. Viscosity increases dramatically upon cooling, until dynamical arrest when a glassy state is reached. Water is a notoriously poor glassformer, and the supercooled liquid crystallizes easily, making the measurement of its viscosity a challenging task. Here we report viscosity of water supercooled close to the limit of homogeneous crystallization. Our values contradict earlier data. A single power law reproduces the 50-fold variation of viscosity up to the boiling point. Our results allow us to test the Stokes–Einstein and Stokes–Einstein–Debye relations that link viscosity, a macroscopic property, to the molecular translational and rotational diffusion, respectively. In molecular glassformers or liquid metals, the violation of the Stokes–Einstein relation signals the onset of spatially heterogeneous dynamics and collective motions. Although the viscosity of water strongly decouples from translational motion, a scaling with rotational motion remains, similar to canonical glassformers. PMID:26378128

  12. Measuring viscosity with a resonant magnetic perturbation in the MST RFP

    NASA Astrophysics Data System (ADS)

    Fridström, Richard; Munaretto, Stefano; Frassinetti, Lorenzo; Chapman, Brett; Brunsell, Per; Sarff, John; MST Team

    2016-10-01

    Application of an m = 1 resonant magnetic perturbation (RMP) causes braking and locking of naturally rotating m = 1 tearing modes (TMs) in the MST RFP. The experimental TM dynamics are replicated by a theoretical model including the interaction between the RMP and multiple TMs [Fridström PoP 23, 062504 (2016)]. The viscosity is the only free parameter in the model, and it is chosen such that model TM velocity evolution matches that of the experiment. The model does not depend on the means by which the natural rotation is generated. The chosen value of the viscosity, about 40 m2/s, is consistent with separate measurements in MST using a biased probe to temporarily spin up the plasma. This viscosity is about 100 times larger than the classical prediction, likely due to magnetic stochasticity in the core of these plasmas. Viscosity is a key parameter in visco-resistive MHD codes like NIMROD. The validation of these codes requires measurement of the viscosity over a broad parameter range, which will now be possible with the RMP technique that, unlike the biased probe, is not limited to low-energy-density plasmas. Estimation with the RMP technique of the viscosity in several MST discharges suggests that the viscosity decreases as the electron beta increases. Work supported by USDOE.

  13. Control of ideal and resistive magnetohydrodynamic modes in reversed field pinches with a resistive wall

    SciTech Connect

    Richardson, A. S.; Finn, J. M.; Delzanno, G. L.

    2010-11-15

    Numerical studies of magnetohydrodynamic (MHD) instabilities with feedback control in reversed field pinches (RFPs) are presented. Specifically, investigations are performed of the stability of m=1 modes in RFPs with control based on sensing the normal and tangential magnetic fields at the resistive wall and applying two-parameter feedback proportional to these fields. The control scheme is based on that of [J. M. Finn, Phys. Plasmas 13, 082504 (2006)], which is here modified to use a more realistic plasma model. The plasma model now uses full resistive MHD rather than reduced MHD, and it uses three realistic classes of equilibrium parallel current density profiles appropriate to RFPs. Results with these modifications are in qualitative agreement with [J. M. Finn, Phys. Plasmas 13, 082504 (2006)]: the feedback can stabilize tearing modes (with resistive or ideal-wall) and resistive wall ideal modes. The limit for stabilization is again found to be near the threshold for ideal modes with an ideal-wall. In addition to confirming these predictions, the nature of the instabilities limiting the range of feedback stabilization near the ideal-wall ideal-plasma threshold are studied, and the effects of viscosity, resistive wall time, and plasma resistivity are reported.

  14. Solar polar rotation and its effect on heliospheric neutral fluxes

    NASA Astrophysics Data System (ADS)

    Sokol, J. M.; Grzedzielski, S.; Bzowski, M.

    2016-12-01

    The magnetic field in the solar polar corona exhibit a regular "ray-like" structure associated with large polar coronal holes during solar minimum. The solar rotation twists the magnetic field lines of the expanding fast solar wind over the poles. The twist induces a toroidal component of the polar magnetic field which results in magnetic forces directed towards the rotation axis. That is tantamount to a (weak) zeta pinch, known also in other astrophysical contexts (e.g. AGN plasmas). The pinch compresses the polar solar corona plasma and a cone-like enhancement in the solar wind density forms along the rotation axis. Though the effect is likely very dynamic, a time independent description is used here to get an order-of-magnitude estimate. The weak pinch is treated as a 1st order perturbation to the zero-order radial flow. The obtained density enhancement may affect the near and far heliosphere, modifying the charge-exchange and electron impact ionization rates of neutral atoms in interplanetary space. The charge exchange is the most effective ionization process for hydrogen and oxygen atoms, and electron impact ionization is a significant loss reaction for the helium atoms at close distances to the Sun. The change in the polar density due to the solar polar corona rotation could be of importance in the inner heliosphere for low energy atoms. We will present the influence of this effect on interstellar neutral gas distribution and H ENA fluxes observed by IBEX.

  15. Differential rotation in solar convective dynamo simulations

    NASA Astrophysics Data System (ADS)

    Fan, Yuhong; Fang, Fang

    2016-10-01

    We carry out a magneto-hydrodynamic (MHD) simulation of convective dynamo in the rotating solar convective envelope driven by the solar radiative diffusive heat flux. The simulation is similar to that reported in Fan and Fang (2014) but with further reduced viscosity and magnetic diffusion. The resulting convective dynamo produces a large scale mean field that exhibits similar irregular cyclic behavior and polarity reversals, and self-consistently maintains a solar-like differential rotation. The main driver for the solar-like differential rotation (with faster rotating equator) is a net outward transport of angular momentum away from the rotation axis by the Reynolds stress, and we found that this transport is enhanced with reduced viscosity and magnetic diffusion.

  16. Influence of toroidal rotation on resistive tearing modes in tokamaks

    SciTech Connect

    Wang, S.; Ma, Z. W.

    2015-12-15

    Influence of toroidal equilibrium plasma rotation on m/n = 2/1 resistive tearing modes is studied numerically using a 3D toroidal MHD code (CLT). It is found that the toroidal rotation with or without shear can suppress the tearing instability and the Coriolis effect in the toroidal geometry plays a dominant role on the rotation induced stabilization. For a high viscosity plasma (τ{sub R}/τ{sub V} ≫ 1, where τ{sub R} and τ{sub V} represent resistive and viscous diffusion time, respectively), the effect of the rotation shear combined with the viscosity appears to be stabilizing. For a low viscosity plasmas (τ{sub R}/τ{sub V} ≪ 1), the rotation shear shows a destabilizing effect when the rotation is large.

  17. Studies on electromagnetic and charged particles radiations from pinched plasma sources

    NASA Astrophysics Data System (ADS)

    Neog, Nirod Kumar

    Nuclear fusion is a process in which under certain condition, two light nuclei combine together to form a new heavier nucleus with consequent release of energy. It is to be noted that two fusing nuclei must come closer and closer until they react to form a single nucleus. But it is very difficult to squeeze of two nuclei to form a heavy nucleus due to the electrostatic coulomb repulsion between them. So, in order to over come this mutual electrostatic repulsion, the nuclei must have enough kinetic energy. This can be achieved by giving thermal energy to the fusing nuclei. Different schemes (like pinch effect, inertial confinement, magnetic confinement, etc.) have come out to provide necessary thermal energy to the fusing nuclei. One of such remarkable scheme, pinch effect, was invented during the mid of last century to achieve nuclear fusion. When a large current is passed through a conducting gas medium, its setup an azimuthal magnetic field, which tends to pinch the gas at the axis, thus generating high temperature and high density conducting ionized gas (plasma). This phenomenon is called as pinch effect. The self-generated magnetic field of the pinching plasma gives necessary thermal energy for fuse of light nuclei. A theory of pinch effect was first put forward by Bennett and later improved by others. The attempts of getting pinch fusion plasma led to give birth of theta-pinch and Z-pinch devices. Though both the approaches have failed to achieve the desired goal due to various plasma instabilities and other factors, still these devices are used in laboratories to study pinch plasma and to understand the mechanisms of neutron production, ion and electron production, and X-ray emission. Various other devices like compressional Z-pinch, exploding wire Z-pinch, gas puff Z-pinch, vacuum spark, gas embedded Z-pinch, capillary discharge plasma and plasma focus based on the principle of Z-pinch have developed in different laboratories all around the world to over

  18. Oscillatory patterns in a rotating aqueous suspension.

    PubMed

    Breu, A P J; Kruelle, C A; Rehberg, I

    2004-02-01

    Suspensions of granular material in glycerin-water mixtures agitated in horizontally aligned rotating tubes show a whole variety of patterns. The stationary pattern of a homogeneous distribution and a chain of rings have been investigated before. Here we report on two types of oscillatory states in the same system. For a certain range of the rotation frequency and sufficiently high viscosity traveling waves propagate with constant velocity back and forth along the tube in an almost homogeneous distribution of sedimenting particles. The transition from a stationary to the traveling-wave state is found to be an imperfect supercritical bifurcation. The dependence of the wave length and speed on the tube's rotation frequency and the dynamic viscosity of the fluid are determined. Experiments with low viscosities show no traveling waves but low-frequency oscillations, when the previously known chain of rings undergoes a secondary instability.

  19. An Inertial-Fusion Z-Pinch Power Plant Concept

    SciTech Connect

    DERZON,MARK S.; ROCHAU,GARY E.; DEGROOT,J.; OLSON,CRAIG L.; PETERSON,P.; PETERSON,R.R.; SLUTZ,STEPHEN A.; ZAMORA,ANTONIO J.

    2000-12-15

    With the promising new results of fast z-pinch technology developed at Sandia National Laboratories, we are investigating using z-pinch driven high-yield Inertial Confinement Fusion (ICF) as a fusion power plant energy source. These investigations have led to a novel fusion system concept based on an attempt to separate many of the difficult fusion engineering issues and a strict reliance on existing technology, or a reasonable extrapolation of existing technology, wherever possible. In this paper, we describe the main components of such a system with a focus on the fusion chamber dynamics. The concept works with all of the electrically-coupled ICF proposed fusion designs. It is proposed that a z-pinch driven ICF power system can be feasibly operated at high yields (1 to 30 GJ) with a relatively low pulse rate (0.01-0.1 Hz). To deliver the required current from the rep-rated pulse power driver to the z-pinch diode, a Recyclable Transmission Line (RTL) and the integrated target hardware are fabricated, vacuum pumped, and aligned prior to loading for each power pulse. In this z-pinch driven system, no laser or ion beams propagate in the chamber such that the portion of the chamber outside the RTL does not need to be under vacuum. Additionally, by utilizing a graded-density solid lithium or fluorine/lithium/beryllium eutectic (FLiBe) blanket between the source and the first-wall the system can breed its own fuel absorb a large majority of the fusion energy released from each capsule and shield the first-wall from a damaging neutron flux. This neutron shielding significantly reduces the neutron energy fluence at the first-wall such that radiation damage should be minimal and will not limit the first-wall lifetime. Assuming a 4 m radius, 8 m tall cylindrical chamber design with an 80 cm thick spherical FLiBe blanket, our calculations suggest that a 20 cm thick 6061-T6 Al chamber wall will reach the equivalent uranium ore radioactivity level within 100 years after a 30

  20. Viscosity of the earth's core

    NASA Technical Reports Server (NTRS)

    Hide, R.

    1972-01-01

    Estimates of the coefficient of kinematical viscosity nu of the earth's liquid metallic core that are given in the geophysical literature range from approximately 0.001 sq cm/s, the viscosity of molten iron at ordinary pressures, to approximately less than 10 to the 8th power sq cm/s, based on the observation that compressional waves traverse the core without suffering serious attenuation. Bumps on the core-mantle boundary with typical horizontal dimensions up to a few thousand km and vertical dimensions h of a few km would produce the topographic coupling between the core and mantle that is evidently implied by the observed decade variations in the length of the day (unless the coupling is due to the presence of rapidly fluctuating magnetic fields in the core).

  1. Shear viscosity of nuclear matter

    NASA Astrophysics Data System (ADS)

    Magner, A. G.; Gorenstein, M. I.; Grygoriev, U. V.; Plujko, V. A.

    2016-11-01

    Shear viscosity η is calculated for the nuclear matter described as a system of interacting nucleons with the van der Waals (VDW) equation of state. The Boltzmann-Vlasov kinetic equation is solved in terms of the plane waves of the collective overdamped motion. In the frequent-collision regime, the shear viscosity depends on the particle-number density n through the mean-field parameter a , which describes attractive forces in the VDW equation. In the temperature region T =15 -40 MeV, a ratio of the shear viscosity to the entropy density s is smaller than 1 at the nucleon number density n =(0.5 -1.5 ) n0 , where n0=0.16 fm-3 is the particle density of equilibrium nuclear matter at zero temperature. A minimum of the η /s ratio takes place somewhere in a vicinity of the critical point of the VDW system. Large values of η /s ≫1 are, however, found in both the low-density, n ≪n0 , and high-density, n >2 n0 , regions. This makes the ideal hydrodynamic approach inapplicable for these densities.

  2. Viscosity Index Improvers and Thickeners

    NASA Astrophysics Data System (ADS)

    Stambaugh, R. L.; Kinker, B. G.

    The viscosity index of an oil or an oil formulation is an important physical parameter. Viscosity index improvers, VIIs, are comprised of five main classes of polymers: polymethylmethacrylates (PMAs), olefin copolymers (OCPs), hydrogenated poly(styrene-co-butadiene or isoprene) (HSD/SIP/HRIs), esterified polystyrene-co-maleic anhydride (SPEs) and a combination of PMA/OCP systems. The chemistry, manufacture, dispersancy and utility of each class are described. The comparative functions, properties, thickening ability, dispersancy and degradation of VIIs are discussed. Permanent and temporary shear thinning of VII-thickened formulations are described and compared. The end-use performance and choice of VI improvers is discussed in terms of low- and high-temperature viscosities, journal bearing oil film thickness, fuel economy, oil consumption, high-temperature pumping efficiency and deposit control. Discussion of future developments concludes that VI improvers will evolve to meet new challenges of increased thermal-oxidative degradation from increased engine operating temperatures, different base stocks of either synthetic base oils or vegetable oil-based, together with alcohol- or vegetable oil-based fuels. VI improvers must also evolve to deal with higher levels of fuel dilution and new types of sludge and also enhanced low-temperature requirements.

  3. Local viscosity and environment on the nanometer scale

    NASA Astrophysics Data System (ADS)

    Jeon, Sangmin

    2002-01-01

    Local viscosity and environment of various systems were studied by electrical, mechanical and optical methods. Dielectric loss peaks of both normal-mode relaxation and of segmental motion of cis-polyisoprene with various molecular weights were measured at different film thickness. While the normal mode relaxation was retarded as film thickness decreases, segemental mode was not. This contrasting thickness and temperature dependence of the normal-mode and segmental relaxtion modes indicates strong breakdown of time-temperature superposition. Furthermore, the normal mode relaxation of the lower molecular weight polyisoprene showed more retardation than that of higher one. Both large shear with low frequency and small shear with high frequency were applied to molecularly confined OMCTS (Octamethylcyclotetrasiloxane) inside SFA to observe its stick to slip transition. Large shear caused the structural changes of the film and small shear probed the rheological properties of the confined liquid during the slow large shear process. Shear probe also detected dynamic lateral alignment of OMCTS near mica surface during the repeated approaches and separations. When triangular normal force was applied, force distance profile and viscoelastic components were measured at the same time by capacitance and shear device respectively. Although each OMCTS layer always appears at the same distance from the solid wall, its viscoelastic measurement showed additional sub changes even at the same film thickness. New optical setup for two photon excitation time-resolved fluorescence anisotropy and lifetime measurements was built and used to understand the local environment and viscosity. The rotational correlation time constants by the fluorescence anisotropy provide the information on the hydrodynamic volume and local viscosity near the probe. Instead, the fluorescence lifetime does the local environment near the probe such as pH, temperature and polarity of the medium. Based on these

  4. Spectroscopic studies on di-pophyrin rotor as micro-viscosity sensor

    NASA Astrophysics Data System (ADS)

    Doan, H.; Raut, S.; Kimbal, J.; Gryczynski, Z.; Dzyuba, S.; Balaz, M.

    2015-03-01

    In typical biological systems the fluid compartment makes up more than 70% percent of the system weight. A variety of mass and signal transportation as well as intermolecular interactions are often governed by viscosity. It is important to be able to measure/estimate viscosity and detect the changes in viscosity upon various stimulations. Understanding the influence of changes in viscosity is crucial and development of the molecular systems that sensitive to micro-viscosity is a goal of many researches. Molecular rotors have been considered the potential target since they present enhanced sensitivity to local viscosity that can strongly restrict molecular rotation. To understand the mechanics of rotor interaction with the environment we have been studied conjugated pophyrin-dimer rotor (DP) that emit in the near IR. Our goal is to investigate the photo physical properties such as absorption, transition moment orientation, emission and excitation, polarization anisotropy and fluorescence lifetime in various mediums of different viscosities from ethanol to poly vinyl alcohol (PVA) matrices. The results imply the influences of the medium's viscosity on the two distinct confirmations: planar and twisted conformations of DP. Linear dichroism from polarized absorption in PVA matrices shows various orientations of transition moments. Excitation anisotropy shows similar transition splitting between two conformations. Time resolved intensity decay at two different observations confirms the two different emission states and furthermore the communication between the two states in the form of energy transfer upon excitation.

  5. Density and viscosity of lipids under pressure

    USDA-ARS?s Scientific Manuscript database

    There is a lack of data for the viscosity of lipids under pressure. The current report is a part of the effort to fill this gap. The viscosity, density, and elastohydrodynamic film thicknesses of vegetable oil (HOSuO) were investigated. Pressure–viscosity coefficients (PVC) of HOSuO at different tem...

  6. Advanced feedback control methods in EXTRAP T2R reversed field pinch

    NASA Astrophysics Data System (ADS)

    Yadikin, D.; Brunsell, P. R.; Paccagnella, R.

    2006-07-01

    Previous experiments in the EXTRAP T2R reversed field pinch device have shown the possibility of suppression of multiple resistive wall modes (RWM). A feedback system has been installed in EXTRAP T2R having 100% coverage of the toroidal surface by the active coil array. Predictions based on theory and the previous experimental results show that the number of active coils should be sufficient for independent stabilization of all unstable RWMs in the EXTRAP T2R. Experiments using different feedback schemes are performed, comparing the intelligent shell, the fake rotating shell, and the mode control with complex feedback gains. Stabilization of all unstable RWMs throughout the discharge duration of td≈10τw is seen using the intelligent shell feedback scheme. Mode rotation and the control of selected Fourier harmonics is obtained simultaneously using the mode control scheme with complex gains. Different sensor signals are studied. A feedback system with toroidal magnetic field sensors could have an advantage of lower feedback gain needed for the RWM suppression compared to the system with radial magnetic field sensors. In this study, RWM suppression is demonstrated, using also the toroidal field component as a sensor signal in the feedback system.

  7. Advanced feedback control methods in EXTRAP T2R reversed field pinch

    SciTech Connect

    Yadikin, D.; Brunsell, P. R.; Paccagnella, R.

    2006-07-15

    Previous experiments in the EXTRAP T2R reversed field pinch device have shown the possibility of suppression of multiple resistive wall modes (RWM). A feedback system has been installed in EXTRAP T2R having 100% coverage of the toroidal surface by the active coil array. Predictions based on theory and the previous experimental results show that the number of active coils should be sufficient for independent stabilization of all unstable RWMs in the EXTRAP T2R. Experiments using different feedback schemes are performed, comparing the intelligent shell, the fake rotating shell, and the mode control with complex feedback gains. Stabilization of all unstable RWMs throughout the discharge duration of t{sub d}{approx_equal}10{tau}{sub w} is seen using the intelligent shell feedback scheme. Mode rotation and the control of selected Fourier harmonics is obtained simultaneously using the mode control scheme with complex gains. Different sensor signals are studied. A feedback system with toroidal magnetic field sensors could have an advantage of lower feedback gain needed for the RWM suppression compared to the system with radial magnetic field sensors. In this study, RWM suppression is demonstrated, using also the toroidal field component as a sensor signal in the feedback system.

  8. The linear model and experimentally observed resonant field amplification in tokamaks and reversed field pinches

    SciTech Connect

    Pustovitov, V. D.

    2011-01-15

    A review is given of the experimentally observed effects related to the resonant field amplification (RFA) and the Resistive Wall Mode (RWM) instability in tokamaks and reversed field pinches (RFPs). This includes the feedback rotation of RWM in RFX-mod RFP, dependence of the RWM growth rate on the plasma-wall separation observed in JT-60U, appearance of the slowly growing RWM precursors in JT-60U and similar phenomena in other devices. The experimental results are compared with theoretical predictions based on the model comprising the Maxwell equations, Ohm's law for the conducting wall, the boundary conditions and assumption of linear plasma response to the external magnetic perturbations. The model describes the plasma reaction to the error field as essentially depending on two factors: the plasma proximity to the RWM stability threshold and the natural rotation frequency of the plasma mode. The linear response means that these characteristics are determined by the plasma equilibrium parameters only. It is shown that the mentioned effects in different devices under different conditions can be described on a common basis with only assumption that the plasma behaves as a linear system. To extend the range of the model validation, some predictions are derived with proposals for experimental studies of the RFA dynamics.

  9. Use of X-pinches of diagnose behavior of low density CH foams on axis of wire array Z-pinches

    SciTech Connect

    Bott, S.C.; Palmer, J.B.A.; Ampleford, D.J.; Bland, S.N.; Chittenden, J.P.; Lebedev, S.V.

    2004-10-01

    X-pinch radiography was used to analyze the interaction between streams of coronal plasma and on-axis foam targets in wire array z-pinch experiments on the MAGPIE generator (1 MA,240 ns). The implosion of the x-pinch, used in place of a current return conductor to the load, provided a short (<2 s) small ({approx}5 {mu}m) intense burst of soft x-rays, ideal for point projection backlighting. Timimg of the x-pinch was adjusted via the mass of its wires, allowing us to study the evolution of the foam during the experiment. Choice of the x-pinch materials, filters, and recording film determined the probing radiation, and hence the plasma/foam densities were resolved. Quantitative results will be discussed.

  10. Transition from column to micropinch regime in Z-pinches

    SciTech Connect

    Engel, A.; Lebert, R.; Koshelev, K. N.; Sidelnikov, Yu. V.; Gavrilescu, C.; Neff, W.

    1997-05-05

    Plasma focus and Z-pinches are known to be intensive sources of K-ion radiation. This radiation is observed in two different regimes of compression: column and micropinch. Appearance of these regimes depends on combination of discharge circuit parameter and element composition of plasma. Column regime is typical for low current discharges operating in low Z gases. Micropinch regime, which represents a development of ''neck'' type instabilities in a presence of strong radiation losses, is typical for heavy ion plasma, i.e. vacuum spark or plasma focus with admixture of heavy gases. Transition from column to micropinch mode has been investigated experimentally. It was found that appearance of either regime can be quantitatively described by a distinction parameter depending on pinch current, particle density and used element.

  11. Characterisation of Plasma Filled Rod Pinch electron beam diode operation

    NASA Astrophysics Data System (ADS)

    MacDonald, James; Bland, Simon; Chittenden, Jeremy

    2016-10-01

    The plasma filled rod pinch diode (aka PFRP) offers a small radiographic spot size and a high brightness source. It operates in a very similar to plasma opening switches and dense plasma focus devices - with a plasma prefill, supplied via a number of simple coaxial plasma guns, being snowploughed along a thin rod cathode, before detaching at the end. The aim of this study is to model the PFRP and understand the factors that affect its performance, potentially improving future output. Given the dependence on the PFRP on the prefill, we are making detailed measurements of the density (1015-1018 cm-3), velocity, ionisation and temperature of the plasma emitted from a plasma gun/set of plasma guns. This will then be used to provide initial conditions to the Gorgon 3D MHD code, and the dynamics of the entire rod pinch process studied.

  12. Modeling Z-Pinch implosions in two dimensions

    SciTech Connect

    Peterson, D.; Bowers, R.; Brownell, J.

    1997-12-31

    Ideally, simulations of Z-Pinch implosions should provide useful information about important physics processes underlying observed experimental results and provide design capabilities for future experiments. With this goal the authors have developed a methodology for simulating hollow Z-Pinches in two dimensions and applied it to experiments conducted on the Pegasus I and Pegasus II capacitor banks, the Procyon explosion generator system, and the Saturn and PBFA-Z accelerators. In comparisons with experimental results the simulations have reproduced important features of the current drive, spectrum, radiation pulse shape, peak power and total radiated energy. Comparison of the instability development in the simulations with visible light framing camera photos has shown a close correlation with the observed instability wavelengths and amplitudes. Using this methodology the authors are analyzing recent Saturn and PBFA-Z experiments and applying the 2-D modeling in developing applications such as the dynamic hohlraum.

  13. Terahertz pinch harmonics enabled by single nano rods.

    PubMed

    Park, Hyeong-Ryeol; Bahk, Young-Mi; Choe, Jong Ho; Han, Sanghoon; Choi, Seong Soo; Ahn, Kwang Jun; Park, Namkyoo; Park, Q-Han; Kim, Dai-Sik

    2011-11-21

    A pinch harmonic (or guitar harmonic) is a musical note produced by lightly pressing the thumb of the picking hand upon the string immediately after it is picked [J. Chem. Educ. 84, 1287 (2007)]. This technique turns off the fundamental and all overtones except those with a node at that location. Here we present a terahertz analogue of pinch harmonics, whereby a metallic nano rod placed at a harmonic node on a terahertz nanoresonator suppresses the fundamental mode, making the higher harmonics dominant. Strikingly, a skin depth-wide nano rod placed at the mid-point turns off all resonances. Our work demonstrates that terahertz electromagnetic waves can be tailored by nanoparticles strategically positioned, paving important path towards terahertz switching and detection applications.

  14. Tungsten Z-Pinch Long Implosions on the Saturn Generator

    SciTech Connect

    DOUGLAS,MELISSA R.; DEENEY,CHRISTOPHER; SPIELMAN,RICK B.; COVERDALE,CHRISTINE A.; RODERICK,N.F.; HAINES,M.G.

    1999-11-05

    Recent success on the Saturn and Z accelerators at Sandia National Laboratories have demonstrated the ability to scale z-pinch parameters to increasingly larger current pulsed power facilities. Next generation machines will require even larger currents (>20 MA), placing further demands on pulsed power technology. To this end, experiments have been carried out on Saturn operating in a long pulse mode, investigating the potential of lower voltages and longer implosion times while still maintaining pinch fidelity. High wire number, 25 mm diameter tungsten arrays were imploded with implosion times ranging from 130 to 240 ns. The results were comparable to those observed in the Saturn short pulse mode, with risetimes on the order of 4.5 to 6.5 ns. Experimental data will be presented, along with two dimensional radiation magnetohydrodynamic simulations used to explain and reproduce the experiment.

  15. Light detonation wave in a cylindrical Z-pinch

    NASA Astrophysics Data System (ADS)

    Yusupaliev, U.; Sysoev, N. N.; Shuteev, S. A.; Elenskii, V. G.

    2015-09-01

    A secondary compression wave previously observed by other researchers in a cylindrical Z-pinch has been identified in this work as a light detonation wave. It appears on the inner surface of a discharge chamber under the action of the intense ultraviolet radiation from a plasma pinch at the stage of its maximum compression. The condition of the light detonation wave has been determined experimentally. The dependence of its Mach number on a generalized dimensionless variable has been determined taking into account the conservation laws for the light detonation wave including the pressure of the gas, expenses on the formation of the surface plasma, and the energy of ionization of the gas involved in the wave. An analogy with the laser-supported detonation wave created by intense laser radiation has been revealed. The indicated dependence is within the error of measurement in agreement with the experimental data for light detonation waves created by both methods.

  16. Focused Aerosol Targets for Z-pinch Loads

    NASA Astrophysics Data System (ADS)

    Gunderson, L. M.; Ruiz, D.; Fisch, N. J.; Hay, M. J.; Merino, E.; Valeo, E. J.; Wissel, S.; Zweben, S. J.

    2013-10-01

    Aerodynamic focusing of aerosols might be used as the load in Z-pinch devices, offering an alternative to wire arrays or gas puffs. Motivations for investigating this method include: better axial uniformity in the material profile, tailoring the radial density and material profile with fewer physical alterations to the machine, and more versatility in load material. In Z-pinches for K-shell X-ray sources, aerosols of metals, such as Aluminum, might be used to compare the dynamics of diffusely distributed loads (similar to gas puffs) versus wire arrays of the same material, which are suspected to be more subject to seeding Magneto-Rayleigh-Taylor instabilities. Work supported by DOE under DE-AC02-09CH11466 and DE-NA0001836.

  17. Statistical hydromechanics of the solar differential rotation.

    PubMed

    Monin, A S; Simuni, L M

    1982-06-01

    An axisymmetric hydrodynamic model of the solar differential rotation is suggested that differs from the previous axisymmetric models (with arbitrarily given anisotropic viscosity) in the use of the hydrodynamic equations (the Friedmann-Keller equations) for the statistical second moments of the fluctuations of velocity and entropy-i.e., turbulent fluxes of momentum and entropy. The model gives a correct reproduction of the differential rotation (without unreal temperature differences on the Sun's surface peculiear to the anisotropic viscosity models) and makes possible calculations of the second moments.

  18. Characteristics of switching plasma in an inverse-pinch switch

    NASA Technical Reports Server (NTRS)

    Lee, Ja H.; Choi, Sang H.; Venable, Demetrius D.; Han, Kwang S.; Nam, Sang H.

    1993-01-01

    Characteristics of the plasma that switches on tens of giga volt-ampere in an inverse-pinch plasma switch (INPIStron) have been made. Through optical and spectroscopic diagnostics of the current carrying plasma, the current density, the motion of current paths, dominant ionic species have been determined in order to access their effects on circuit parameters and material erosion. Also the optimum operational condition of the plasma-puff triggering method required for azimuthally uniform conduction in the INPIStron has been determined.

  19. Experimental Comparison of Capillary Pinching Discharge in Argon and Nitrogen

    NASA Astrophysics Data System (ADS)

    Jancarek, A.; Pina, L.; Vrbova, M.; Tamas, M.; Havlikova, R.; Palinek, S.; Vrba, P.; Kolacek, K.; Schmidt, J.; Strauss, J.

    Experiments with CAPEX-U apparatus were done to more understand the differences between Ar and N active media created during the pinch compression, respectively. Capillary discharge current, X-ray narrow band radiation and EUV spectrum temporal behavior were measured. Results of laboratory experiments for both gas fillings under various currents and initial pressures are shown. Computer simulations show that current quasi-period shortening and higher amplitude is needed.

  20. Cu spectroscopy from a z-pinch plasma

    NASA Astrophysics Data System (ADS)

    Dasgupta, Arati; Clark, Robert W.; Ouart, Nicholas D.; Giuliani, John L.

    2014-11-01

    Recent improvements in diagnostic techniques at the Sandia Laboratories Z accelerator have facilitated the production of very detailed x-ray spectral data in the range of 1-20 keV. The high energy density plasma produced in a z-pinch is inherently in non-local thermodynamic equilibrium (NLTE). We therefore employ a NLTE collisional equilibrium model in a 1D radiation-magnetohydrodynamics code to simulate the dynamics of the pinch and to generate synthetic emission spectra. We will discuss the effects on radiation spectra and the yields of using simplifying assumptions in the atomic model and/or the radiation transport. X-ray emission from moderately high atomic number plasmas such as Fe and Cu wire array implosions often include substantial 2p-1s K-α radiation. In a z-pinch plasma, K-shell vacancies can be produced by e-beams, hot electrons at the tail of a Maxwellian and also by photopumping from energetic photons emitted near the pinch axis. In the Z-1975 Cu wire implosion, K-α lines from various ionization stages of Cu as well as from minor constituents including Ni, Fe and Cr are observed. We have calculated K-α production within a full simulation of a Cu implosion, including contributions from energetic electrons and photons. Photo-pumped K-α emission can be distinguished from that produced by e-beams; K-shell vacancies will be produced near the axis for a beam, and near the outer edge of the plasma for energetic photons. Spectroscopic modeling of these K-α lines as well as K- and L-shell emission from valence electrons can provide quantitative diagnostics of plasma parameters. This methodology can also be used to investigate K-α emission from other laboratory experiments such as EBIT and astrophysical plasmas.

  1. A Lagrangian approach to identifying vortex pinch-off.

    PubMed

    O'Farrell, Clara; Dabiri, John O

    2010-03-01

    A criterion for identifying vortex ring pinch-off based on the Lagrangian coherent structures (LCSs) in the flow is proposed and demonstrated for a piston-cylinder arrangement with a piston stroke to diameter (L/D) ratio of approximately 12. It is found that the appearance of a new disconnected LCS and the termination of the original LCS are indicative of the initiation of vortex pinch-off. The subsequent growth of new LCSs, which tend to roll into spirals, indicates the formation of new vortex cores in the trailing shear layer. Using this criterion, the formation number is found to be 4.1+/-0.1, which is consistent with the predicted formation number of approximately 4 of Gharib et al. [Gharib et al. J. Fluid Mech. 360, 121 (1998)]. The results obtained using the proposed LCS criterion are compared with those obtained using the circulation criterion of Gharib et al. and are found to be in excellent agreement. The LCS approach is also compared against other metrics, both Lagrangian and Eulerian, and is found to yield insight into the pinch-off process that these do not. Furthermore, the LCS analysis reveals a consistent pattern of coalescing or "pairing" of adjacent vortices in the trailing shear layer, a process which has been extensively documented in circular jets. Given that LCSs are objective and insensitive to local errors in the velocity field, the proposed criterion has the potential to be a robust tool for pinch-off identification. In particular, it may prove useful in the study of unsteady and low Reynolds number flows, where conventional methods based on vorticity prove difficult to use.

  2. Quasi-steady operation of reversed field pinches

    SciTech Connect

    Nebel, R.A.

    1980-01-01

    A three fluid, Lagrangian mesh, transport and stability code (RFPBRN) has been developed and applied to the Reversed Field Pinch reactor concept. Using a circular cylinder, quasi-static approximation, RFPBRN follows the time evolution of the temperature, density, and magnetic field profiles for the RFP while simultaneously monitoring ideal MHD stability. Local stability is monitored for Suydam modes while global stability is monitored using a Rayleigh-Ritz expansion of the energy principle.

  3. Validity testing of the accuPINCH THC test.

    PubMed

    Jenkins, A J; Darwin, W D; Huestis, M A; Cone, E J; Mitchell, J M

    1995-01-01

    Self-contained drug-testing kits are currently being marketed for a variety of drugs of abuse. These tests are designed to provide rapid access to test results without the need for laboratory facilities. This report describes a validity study of the accuPINCH THC test, a self-contained test for cannabinoids in urine. Three healthy male volunteers with a history of marijuana use participated in the clinical study. Each subject smoked one, two, or four marijuana cigarettes (2.6% THC) on each test day. Urine samples were collected and incorporated into a specimen set consisting of 178 clinical samples, 72 urine samples containing known amounts of drug, and 50 drug-free urine samples. The specimen set was randomized and analyzed under blind conditions by the accuPINCH test and by gas chromatography-mass spectrometry (GC-MS) for 11-nor-9-carboxy-delta 9-tetrahydrocannabinol (THCCOOH). AccuPINCH results were interpreted independently by three readers as positive at either two calibration points (positive A < 100 ng/mL THCCOOH; positive B > or = 100 ng/mL THCCOOH) or negative. Concordance analysis was performed by comparison of the accuPINCH results with GC-MS. In addition, the effects of changes in sample turbidity, temperature, and assay reading time on test outcome were assessed. For the clinical samples, positive B results were associated exclusively with THCCOOH concentrations greater than or equal to 15 ng/mL, whereas positive A and negative results were obtained at all concentrations. All drug-free urine samples were interpreted as either negative or positive A. The test demonstrated relatively low cross-reactivity with THC and other cannabinoids.(ABSTRACT TRUNCATED AT 250 WORDS)

  4. Viscosity of the Earth's inner core: constraints from nutation observations

    NASA Astrophysics Data System (ADS)

    Koot, L.; Dumberry, M.

    2010-12-01

    Nutations are the variations in the orientation of the Earth’s rotation axis in a space-fixed reference frame. This motion shows two important normal modes, the Free Core Nutation (FCN) and the Free Inner Core Nutation (FICN), of which the frequencies and damping depend directly on the Earth’s interior structure and dynamics. The FICN is characterized by a differential rotation of the inner core relative to the mantle and outer core. Its natural frequency is thus directly affected both by the strength of the mechanical coupling at the inner core boundary (ICB) and by the way the inner core deforms due to centrifugal forces. Similarly, the damping of the mode reflects the energy dissipated both through the coupling at the ICB and through inner core deformation. Estimations of the ICB coupling strength and dissipation have been obtained previously from nutation observations by assuming a purely elastic inner core (Mathews et al. 2002, Koot et al. 2010). When interpreted in terms of a visco-magnetic coupling, these estimations lead to values of the magnetic field at the ICB around 6-7 mT and to a kinematic viscosity of the fluid core close to the ICB in the range of 10-30 m2 s-1. This value of the ICB fluid core viscosity is orders of magnitude larger than what is expected from laboratory measurements and ‘ab initio’ computations. In this work, we show that a visco-elastic inner core is able to reconcile the estimation of the outer core kinematic viscosity with that of laboratory measurements and ab initio computations. This reconciliation is achieved for a very narrow range of values of the inner core viscosity, which can be considered as a nutation constraint on this physical quantity. Finally, we show that this nutation constraint is in very good agreement with seismic observations of shear waves attenuation in the inner core.

  5. Transport and Measurements of High-Current Electron Beams from X pinches

    SciTech Connect

    Agafonov, Alexey V.; Mingaleev, Albert R.; Romanova, Vera M.; Tarakanov, Vladimir P.; Shelkovenko, Tatiana A.; Pikuz, Sergey A.; Blesener, Isaac C.; Kusse, Bruce R.; Hammer, David A.

    2009-01-21

    Generation of electron beams is an unavoidable property of X-pinches and other pulsed-power-driven pinches of different geometry. Some issues concerning high-current electron beam transport from the X pinch to the diagnostic system and measurements of the beam current by Faraday cups with different geometry's are discussed. Of particular interest is the partially neutralized nature of the beam propagating from the X-pinch to a diagnostic system. Two scenarios of electron beam propagation from X-pinch to Faraday cup are analyzed by means of computer simulation using the PIC-code KARAT. The first is longitudinal neutralization by ions extracted from plasma at an output window of the X-pinch diode; the second is the beam transport through a plasma background between the diode and a diagnostic system.

  6. Simulation tools for pinched-electron-beam radiographic diodes

    NASA Astrophysics Data System (ADS)

    Humphries, Stanley; Orzechowski, Thaddeus

    2006-02-01

    We describe capabilities of an integrated software suite to simulate pinched-electron-beam diodes for pulsed radiography. In contrast to other reported work using particle-in-cell methods, we employ a ray-tracing code (Trak) with advanced capabilities for modeling beam-generated magnetic fields. Ray tracing is a direct approach to a steady-state solution and involves less work than a particle-in-cell calculation. The second software component, GamBet, is a new Monte Carlo code for radiation transport that incorporates effects of the complex electric and magnetic fields at the radiation target. The ray-tracing approach exhibits good convergence in calculations for the diode geometry of the compact radiography (CRAD) program at Lawrence Livermore National Laboratory. With a 1.5 MV, 30 ns driver, we predict that the diode can produce a beam with axial length ˜1 mm that generates isotropic bremsstrahlung radiation exceeding 1 rad at 1 m. The ray-tracing procedure encounters convergence problems when applied to the rod-pinch geometry, a configuration used in several pulsed radiographic machines. We observe a fundamental difference in the nature of electron orbits in the two diodes. There is an increased chance for particle-orbit feedback in the rod pinch, so that equilibrium solutions are sensitive to small changes in emission characteristics.

  7. Diagnostics for Z-pinch implosion experiments on PTS

    SciTech Connect

    Ren, X. D. Huang, X. B. Zhou, S. T. Zhang, S. Q. Dan, J. K. Li, J. Cai, H. C. Wang, K. L. Ouyang, K. Xu, Q. Duan, S. C. Chen, G. H. Wang, M. Feng, S. P. Yang, L. B. Xie, W. P. Deng, J. J.

    2014-12-15

    The preliminary experiments of wire array implosion were performed on PTS, a 10 MA z-pinch driver with a 70 ns rise time. A set of diagnostics have been developed and fielded on PTS to study pinch physics and implosion dynamics of wire array. Radiated power measurement for soft x-rays was performed by multichannel filtered x-ray diode array, and flat spectral responses x-ray diode detector. Total x-ray yield was measured by a calibrated, unfiltered nickel bolometer which was also used to obtain pinch power. Multiple time-gated pinhole cameras were used to produce spatial-resolved images of x-ray self-emission from plasmas. Two time-integrated pinhole cameras were used respectively with 20-μm Be filter and with multilayer mirrors to record images produced by >1-keV and 277±5 eV self-emission. An optical streak camera was used to produce radial implosion trajectories, and an x-ray streak camera paired with a horizontal slit was used to record a continuous time-history of emission with one-dimensional spatial resolution. A frequency-doubled Nd:YAG laser (532 nm) was used to produce four frame laser shadowgraph images with 6 ns time interval. We will briefly describe each of these diagnostics and present some typical results from them.

  8. Effects of EVA spacesuit glove on grasping and pinching tasks

    NASA Astrophysics Data System (ADS)

    Appendino, Silvia; Battezzato, Alessandro; Chen Chen, Fai; Favetto, Alain; Mousavi, Mehdi; Pescarmona, Francesco

    2014-03-01

    The human hand has a wide range of degrees of freedom, allowing a great variety of movements, and is also one of the most sensitive parts of the human body. Due to these characteristics, it is the most important tool for astronauts to perform extravehicular activities (EVA). However, astronauts must wear mandatory EVA equipment to be protected from the harsh conditions in space and this strongly reduces hand performance, in particular as regards dexterity, tactile perception, mobility and fatigue. Several studies have been conducted to determine the influence of the EVA glove on manual capabilities, both in the past and more recently. This study presents experimental data regarding the performance decline occurring in terms of force and fatigue in the execution of grasping and pinching tasks when wearing an EVA glove, in pressurized and unpressurized conditions, compared with barehanded potential. Results show that wearing the unpressurized EVA glove hinders grip and lateral pinch performances, dropping exerted forces to about 50-70%, while it barely affects two- and three-finger pinch performances. On the other hand, wearing the pressurized glove worsens performances in all cases, reducing forces to about 10-30% of barehanded potential. The results are presented and compared with the previous literature.

  9. Self-organized structures in z-pinch devices

    NASA Astrophysics Data System (ADS)

    Ortíz-Tapia, Arturo

    2002-11-01

    In several z-pinch devices there has been observation of regular structures, which appear systematically when repeating the experiments. The fact that very identifiable, recurrent, geometrical structures appear in z-pinches, which are relatively long lived, has motivated the analysis of the experimental data in a way that would cast light over these structures. In order to study this problem, diagnostic methods such as Schlieren photography, Quadro camera diagnostics, X-ray diagnostics, interferometry measurements and streak camera were used. This work includes analysis of experimental results, and the determination of some of the parameters which probably give rise to self-organized structures and some regular structures. It was found that a major contributor, for self-organization to occur, was the dominance of electromagnetic energy over the kinetic energy in the wire corona. The induction of an azimuthal magnetic field contributed to the generation of azimuthal currents, which in turn induced an axial magnetic field. Both axial and azimuthal magnetic fields contributed to the formation of helical-like structures, at least until the pinch began to dissipate. An important stabilizing factor for the plasma channel could have been played by the solid remains of part of the fiber inside the channel. There is a positive strong correlation between the expulsion of entropy and the persistence in the existence of self-organized structures.

  10. Self-pinched chamber transport of heavy ion beams

    NASA Astrophysics Data System (ADS)

    Rose, D. V.; Welch, D. R.; Oliver, B. V.; Yu, S. S.; Olson, C. L.

    2001-10-01

    Self-pinched heavy ion beams are being examined as a chamber transport scheme for heavy-ion-driven inertial confinement fusion. In this scheme, beam-impact-ionization of a low-density background gas provides neutralizing electrons. For certain ranges of background gas pressures the beam is essentially charge-neutralized but incomplete current-neutralization allows the self-magnetic field of the beam to act as a pinch force, confining the beam divergence. Equilibrium transport modes for a Pb^+65 ion beam propagating through low density Xe gas are being studied with particle-in-cell simulations using the LSP code [1]. Time dependent evolution of the beam net current and pinched beam radius as a function of Xe chamber pressure from the simulations is examined. [1] T. P. Hughes, R. E. Clark, and S. S. Yu, Phys. Rev. ST-AB 2, 110401 (1999); D. R. Welch, D. V. Rose, B. V. Oliver, and R. E. Clark, Nucl. Inst. Meth. Phys. Res. A 242, 134 (2001).

  11. Pinch Related Research At Institute For Plasma Research, India

    NASA Astrophysics Data System (ADS)

    Shyam, Anurag

    2006-01-01

    Several pinch related experiment, their drivers and related diagnostics are being developed in our laboratory. The first set of experiments is to investigate various aspects of magnetized target fusion (MTF/MAGO). To drive the liner, in Z or theta pinch configuration, a 1.2 MJ, 3.6 MA capacitor bank is developed. For liner diagnostics flash radiography, VISAR and pyrometery are being developed. To produce magnetized (target) plasma a 120 kJ, 3 MA and several other banks are developed. Hot magnetized Plasma will be diagnosed by optical schlieren, interferometery and X-Ray spectrometry. A terra-watt system consisting of a Marx bank and water line delivering 800 kA at 1.6 MV will be commissioned, soon. The device will be used to study different pinch (wire array) configurations for production of electro-magnetic radiations. Smaller pulsed power systems, consisting of 1MV/500 kV Marx bank/tesla transformer and than water or solid state (cables) pulse forming network (coax) are also being developed for capillary discharge and other experiments. Two plasma foci experiments are also being conducted. The effort is produce a repetitively operating compact plasma focus.

  12. Pinch Related Research At Institute For Plasma Research, India

    SciTech Connect

    Shyam, Anurag

    2006-01-05

    Several pinch related experiment, their drivers and related diagnostics are being developed in our laboratory. The first set of experiments is to investigate various aspects of magnetized target fusion (MTF/MAGO). To drive the liner, in Z or theta pinch configuration, a 1.2 MJ, 3.6 MA capacitor bank is developed. For liner diagnostics flash radiography, VISAR and pyrometery are being developed. To produce magnetized (target) plasma a 120 kJ, 3 MA and several other banks are developed. Hot magnetized Plasma will be diagnosed by optical schlieren, interferometery and X-Ray spectrometry. A terra-watt system consisting of a Marx bank and water line delivering 800 kA at 1.6 MV will be commissioned, soon. The device will be used to study different pinch (wire array) configurations for production of electro-magnetic radiations. Smaller pulsed power systems, consisting of 1MV/500 kV Marx bank/tesla transformer and than water or solid state (cables) pulse forming network (coax) are also being developed for capillary discharge and other experiments. Two plasma foci experiments are also being conducted. The effort is produce a repetitively operating compact plasma focus.

  13. Electromagnetic analysis of arbitrarily shaped pinched carpets

    SciTech Connect

    Dupont, Guillaume; Guenneau, Sebastien; Enoch, Stefan

    2010-09-15

    We derive the expressions for the anisotropic heterogeneous tensors of permittivity and permeability associated with two-dimensional and three-dimensional carpets of an arbitrary shape. In the former case, we map a segment onto smooth curves whereas in the latter case we map an arbitrary region of the plane onto smooth surfaces. Importantly, these carpets display no singularity of the permeability and permeability tensor components. Moreover, a reduced set of parameters leads to nonmagnetic two-dimensional carpets in p polarization (i.e., for a magnetic field orthogonal to the plane containing the carpet). Such an arbitrarily shaped carpet is shown to work over a finite bandwidth when it is approximated by a checkerboard with 190 homogeneous cells of piecewise constant anisotropic permittivity. We finally perform some finite element computations in the full vector three-dimensional case for a plane wave in normal incidence and a Gaussian beam in oblique incidence. The latter requires perfectly matched layers set in a rotated coordinate axis which exemplifies the role played by geometric transforms in computational electromagnetism.

  14. The ZaP Flow Z-Pinch Project - Final Technical Report

    SciTech Connect

    Shumlak, Uri; Nelson, Brian A.

    2013-12-31

    The ZaP Flow Z-Pinch Project is a project to extend the performance of the flow Z-pinch experiment at the University of Washington to investigate and isolate the relevant physics of the stabilizing effect of plasma flow. Experimental plasmas have exhibited an enhanced stability under certain operating parameters which generate a flow state (axial flows in Z-pinches and VH mode in tokamaks). Flow has also been suggested as the stabilizing mechanism in astrophysical jets.

  15. Fully kinetic particle-in-cell simulations of a deuterium gas puff z pinch.

    PubMed

    Welch, D R; Rose, D V; Clark, R E; Mostrom, C B; Stygar, W A; Leeper, R J

    2009-12-18

    We present the first fully kinetic, collisional, and electromagnetic simulations of the complete time evolution of a deuterium gas puff z pinch. Recent experiments with 15-MA current pinches have suggested that the dominant neutron-production mechanism is thermonuclear. We observe distinct differences between the kinetic and magnetohydrodynamic simulations in the pinch evolution with the kinetic simulations producing both thermonuclear and beam-target neutrons. The kinetic approach demonstrated in this Letter represents a viable alternative for performing future plasma physics calculations.

  16. Fully Kinetic Particle-in-Cell Simulations of a Deuterium Gas Puff z Pinch

    SciTech Connect

    Welch, D. R.; Rose, D. V.; Clark, R. E.; Mostrom, C. B.; Stygar, W. A.; Leeper, R. J.

    2009-12-18

    We present the first fully kinetic, collisional, and electromagnetic simulations of the complete time evolution of a deuterium gas puff z pinch. Recent experiments with 15-MA current pinches have suggested that the dominant neutron-production mechanism is thermonuclear. We observe distinct differences between the kinetic and magnetohydrodynamic simulations in the pinch evolution with the kinetic simulations producing both thermonuclear and beam-target neutrons. The kinetic approach demonstrated in this Letter represents a viable alternative for performing future plasma physics calculations.

  17. A biodynamic microsystem for fluids viscosity measurements

    NASA Astrophysics Data System (ADS)

    Marius Avram, Andrei; Avram, Marioara; Bragaru, Adina; Vasilco, Roxana; Iliescu, Ciprian

    2006-04-01

    The purpose of this research was to model, design and fabricate a biodynamic analysis microsystem required for determination of various molecular transport properties of the biological fluids. In order to achieve this, a lab-on-a-chip device was fabricated. The microfluidic system developed satisfies the objectives for the study of microcirculation and characterization of cell rheological properties, functions and behaviour. The measurement principle of the viscosity of biological fluids is based on the detection of the rotation of a polysilicon gear-wheels system. The gear-wheels have external diameters of 250 µm, 200 µm, 160 µm and 3 µm thickness. The micromachining process combines the undercut and refill technique with pin-joint bearing permitting the fabrication of bushings that were used to elevate the rotor away from the silicon surface. The testing of the microfluidic dynamic system was performed using electromagnetic micropumps and magnetic controllers. Each device was fabricated by silicon micromachining technology and tested to obtain the specific characteristics.

  18. Superparamagnetic nanoparticle-based viscosity test

    NASA Astrophysics Data System (ADS)

    Wu, Kai; Liu, Jinming; Wang, Yi; Ye, Clark; Feng, Yinglong; Wang, Jian-Ping

    2015-08-01

    Hyperviscosity syndrome is triggered by high blood viscosity in the human body. This syndrome can result in retinopathy, vertigo, coma, and other unanticipated complications. Serum viscosity is one of the important factors affecting whole blood viscosity, which is regarded as an indicator of general health. In this letter, we propose and demonstrate a Brownian relaxation-based mixing frequency method to test human serum viscosity. This method uses excitatory and detection coils and Brownian relaxation-dominated superparamagnetic nanoparticles, which are sensitive to variables of the liquid environment such as viscosity and temperature. We collect the harmonic signals produced by magnetic nanoparticles and estimate the viscosity of unknown solutions by comparison to the calibration curves. An in vitro human serum viscosity test is performed in less than 1.5 min.

  19. Rotational moulding.

    PubMed

    Crawford, R J; Kearns, M P

    2003-10-01

    Rotational moulding promises designers attractive economics and a low-pressure process. The benefits of rotational moulding are compared here with other manufacturing methods such as injection and blow moulding.

  20. Rotating Vesta

    NASA Image and Video Library

    Astronomers combined 146 exposures taken by NASA's Hubble SpaceTelescope to make this 73-frame movie of the asteroid Vesta's rotation.Vesta completes a rotation every 5.34 hours.› Asteroid and...

  1. An instrumented cylinder measuring pinch force and orientation

    PubMed Central

    Bourbonnais, Daniel; Frak, Victor; Pilon, Jean-François; Goyette, Michel

    2008-01-01

    Background The function of a cylinder allowing simultaneous measurements of the opposition axis of the index finger and thumb of the hand and the magnitude of pinch force is described. Methods The apparatus is made of two half-cylinders that are bonded together through a 6-axis force/torque sensor and allows the measurement of 3D orthogonal forces and moments of force. The amplitude of the pinch force exerted on the cylinder by the fingers is defined as the resultant of the forces in the different axes. A software program was developed to measure the barycentre of the forces on the instrumented cylinder, allowing calculation of the angle of the opposition axis between the fingers and the location of the resulting pinch force on the cylinder, assuming that the pinch or grip forces are co-linear through the center of the cylinder. In order to assess the validity and reliability of the measurements, the cylinder was mounted on a milling table and seven calibrated weights (from 100 to 500 g) were successively applied perpendicularly to a 9*9 matrix of sites separated by 1 cm. With the exception of the extreme lateral parts of the cylinder, the dispersion of the calculated vertical position of the resulting force was always within 1 mm of the application point, suggesting a high reliability of these measurements. In addition, the errors in the angles of the applied force were calculated and found to be less than 2 degree with no clear patterns of variation across the different locations of the cylinder. Results The usefulness of the cylinder is demonstrated by evaluating the pinch force and the opposition axis in six healthy subjects lifting the cylinder from the table using three different orientations of their right hand. The magnitude of the grip force was not significantly different across orientations (45, 22 and -22 degrees relative to the midline of the subject) suggesting that force grip is controlled. Conclusion From these results, it has been concluded that

  2. The Prospects for High-Yield ICF with a Z-Pinch Driven Dynamic Hohlraum

    SciTech Connect

    CHANDLER, GORDON A.; CHRIEN, R.; COOPER, GARY WAYNE; DERZON, MARK S.; DOUGLAS, MELISSA R.; HEBRON, DAVID E.; LASH, JOEL S.; LEEPER, RAMON J.; MATZEN, M. KEITH; MEHLHORN, THOMAS A.; NASH, THOMAS J.; OLSON, RICHARD E.; PETERSON, D.L.; RUIZ, CARLOS L.; SANFORD, THOMAS W. L.; SLUTZ, STEPHEN A.

    1999-09-07

    Recent success with the Sandia Z machine has renewed interest in utilizing fast z-pinenes for ICF. One promising concept places the ICF capsule internal to the imploding z-pinch. At machine parameters relevant to achieving high yield, the imploding z-pinch mass has sufficient opacity to trap radiation giving rise to a dynamic hohlraum. The concept utilizes a 12 MJ, 54 MA z-pinch driver producing a capsule drive temperature exceeding 300 eV to realize a 550 MJ thermonuclear yield. They present the current high-yield design and its development that supports high-yield ICF with a z-pinch driven dynamic hohlraum.

  3. Practical energy and water management through pinch analysis for the pulp and paper industry.

    PubMed

    Koufos, D; Retsina, T

    2001-01-01

    In this paper we briefly describe pinch technology as a practical tool for effective energy management in the pulp and paper industry. Results indicate good steam savings. Recently pinch technology has been extended to water management. We have developed a customized methodology for the pulp and paper industry, to eliminate or reduce fresh water intake. Although the methodology is not fully developed it is a "proof of concept" that pinch principles can be applied to water related problems. The eventual combination of both thermal and water pinch will thus provide a structured and comprehensive approach for plant wide efficiency increase.

  4. Method of adaptive artificial viscosity

    NASA Astrophysics Data System (ADS)

    Popov, I. V.; Fryazinov, I. V.

    2011-09-01

    A new finite-difference method for the numerical solution of gas dynamics equations is proposed. This method is a uniform monotonous finite-difference scheme of second-order approximation on time and space outside of domains of shock and compression waves. This method is based on inputting adaptive artificial viscosity (AAV) into gas dynamics equations. In this paper, this method is analyzed for 2D geometry. The testing computations of the movement of contact discontinuities and shock waves and the breakup of discontinuities are demonstrated.

  5. Effective Viscosity of Microswimmer Suspensions

    NASA Astrophysics Data System (ADS)

    Rafaï, Salima; Jibuti, Levan; Peyla, Philippe

    2010-03-01

    The measurement of a quantitative and macroscopic parameter to estimate the global motility of a large population of swimming biological cells is a challenge. Experiments on the rheology of active suspensions have been performed. Effective viscosity of sheared suspensions of live unicellular motile microalgae (Chlamydomonas Reinhardtii) is far greater than for suspensions containing the same volume fraction of dead cells. In addition, suspensions show shear thinning behavior. We relate these macroscopic measurements to the orientation of individual swimming cells under flow and discuss our results in the light of several existing models.

  6. Effective viscosity of microswimmer suspensions.

    PubMed

    Rafaï, Salima; Jibuti, Levan; Peyla, Philippe

    2010-03-05

    The measurement of a quantitative and macroscopic parameter to estimate the global motility of a large population of swimming biological cells is a challenge. Experiments on the rheology of active suspensions have been performed. Effective viscosity of sheared suspensions of live unicellular motile microalgae (Chlamydomonas Reinhardtii) is far greater than for suspensions containing the same volume fraction of dead cells. In addition, suspensions show shear thinning behavior. We relate these macroscopic measurements to the orientation of individual swimming cells under flow and discuss our results in the light of several existing models.

  7. Critical Viscosity of Xenon team

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The thermostat for CVX sits inside the white cylinder on a support structure (at left) that is placed inside a pressure canister. A similar canister (right) holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (left) of the National Institutes of Standards and Technology, Gaithersburg, MD.

  8. Critical Viscosity of Xenon team

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The thermostat for CVX sits inside the white cylinder on a support structure (at left) that is placed inside a pressure canister. A similar canister (right) holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (left) of the National Institutes of Standards and Technology, Gaithersburg, MD.

  9. Critical Viscosity of Xenon team

    NASA Technical Reports Server (NTRS)

    2001-01-01

    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The thermostat for CVX sits inside the white cylinder on a support structure (at left) that is placed inside a pressure canister. A similar canister (right) holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (not shown) of the National Institutes of Standards and Technology, Gaithersburg, MD.

  10. Lower Hybrid Wave Induced Rotation on Alcator C-Mod

    NASA Astrophysics Data System (ADS)

    Parker, Ron; Podpaly, Yuri; Rice, John; Schmidt, Andrea

    2009-11-01

    Injection of RF power in the vicinity of the lower hybrid frequency has been observed to cause strong counter current rotation in Alcator C-Mod plasmas [1,2]. The spin-up rate is consistent with the rate at which momentum is injected by the LH waves, and also the rate at which fast electron momentum is transferred to the ions. A momentum diffusivity of ˜ 0.1 m^2/s is sufficient to account for the observed steady-state rotation. This value is also comparable with that derived from an analysis of rotation induced by RF mode conversion [3]. Radial force balance requires a radial electric field, suggesting a buildup of negative charge in the plasma core. This may be the result of an inward pinch of the LH produced fast electrons, as would be expected for resonant trapped particles. Analysis of the fast-electron-produced bremsstrahlung during LH power modulation experiments yields an inward pinch velocity of ˜ 1 m/s, consistent with the estimated trapped particle pinch velocity. [4pt] [1] A. Ince-Cushman, et.al., Phys. Rev. Lett., 102, 035002 (2009)[0pt] [2] J. E. Rice, et. al., Nucl. Fusion 49, 025004 (2009)[0pt] [3] Y. Lin, et.al., this meeting

  11. Effect of Liquid Viscosity on the Instability of Polygonal Pattern within a Hollow Vortex Core

    NASA Astrophysics Data System (ADS)

    Mandour, Amr; Abderrahmane, Hamid Ait; Vatistas, Georgios H.; Kadem, Lyes; Ng, Hoi Dick

    2009-11-01

    The present study deals with the effect of the viscosity on the speed and limits of endurance of the polygonal pattern, observed within the hollow-core vortex generated by rotating a flat disc near the bottom of a cylindrical tank. Previous investigations have used water, where the Froude number (Fr) appears as the main control parameter. Varying the viscosity of the fluid introduce another independent control parameter, Reynolds number (Re). Using image and signal processing techniques, the influence of these two control parameters on the dynamics of the polygonal pattern is thoroughly investigated. The viscosity of the rotated fluid is varied by mixing glycerol with water and the mixture viscosity is measured using Zahn cup viscometer. The disc rotational speed is measured and controlled accurately by a PID controller loop using LabView environment. A 3-D bifurcation diagram (Fr,Re,N), where the stability region of N-gon is delimited, is given. Moreover, the influence of the viscosity on the evolution of the N-gon speed is also obtained.

  12. Theory and Simulation of A Novel Viscosity Measurement Method for High Temperature Semiconductor

    NASA Technical Reports Server (NTRS)

    Lin, Bochuan; Li, Chao; Ban, Heng; Scripa, Rose; Zhu, Shen; Su, Ching-Hua; Lehoczky, S. L.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    The properties of molten semiconductors are good indicators for material structure transformation and hysteresis under temperature variations. Viscosity, as one of the most important properties, is difficult to measure because of high temperature, high pressure, and vapor toxicity of melts. Recently, a novel method was developed by applying a rotating magnetic field to the melt sealed in a suspended quartz ampoule, and measuring the transient torque exerted by rotating melt flow on the ampoule wall. The method was designed to measure viscosity in short time period, which is essential for evaluating temperature hysteresis. This paper compares the theoretical prediction of melt flow and ampoule oscillation with the experimental data. A theoretical model was established and the coupled fluid flow and ampoule torsional vibration equations were solved numerically. The simulation results showed a good agreement with experimental data. The results also showed that both electrical conductivity and viscosity could be calculated by fitting the theoretical results to the experimental data. The transient velocity of the melt caused by the rotating magnetic field was found reach equilibrium in about half a minute, and the viscosity of melt could be calculated from the altitude of oscillation. This would allow the measurement of viscosity in a minute or so, in contrast to the existing oscillation cup method, which requires about an hour for one measurement.

  13. Calibration problems with the viscosity measurement of liquid metallurgical slags

    NASA Astrophysics Data System (ADS)

    Heller, H. P.; Schürmann, M.; Scholl, K.; Haustein, N.; Lychatz, B.; Falkus, J.

    2017-01-01

    The viscosity of slag is an important characteristic of liquid slags regarding its lubricating effect and mass transfer. For measurement, however, they exhibit considerable differences in the values reported. Therefore, the rotation method, mostly used for high temperatures areas, is investigated regarding the impacts of any geometric inaccuracies. Furthermore, problems in the centering and use of calibration slags are discussed. It appears that, with the use of a more precise rheometer with air bearing, an error of less than +/- 3 % is possible in compliance with geometric critical values and online monitoring of the central operations. The verification was carried out with a blast furnace slag, which is also proposed as a calibration slag.

  14. A viscosity prescription for a self-gravitating accretion disc

    NASA Technical Reports Server (NTRS)

    Lin, D. N. C.; Pringle, J. E.

    1987-01-01

    A model for treating the transfer of angular momentum within a gaseous differentially rotating disc subject to gravitational instability is discussed in terms of an effective kinematic viscosity. It is assumed that even when matter in the disc is subject to self-gravitation, the instability does not necessarily lead directly to condensation of parts of the disc into self-gravitating bodies. Conditions under which the present model permits a similarity solution are discussed, and it is shown that the general solution tends to the similarity solution at large times.

  15. A viscosity prescription for a self-gravitating accretion disc

    NASA Technical Reports Server (NTRS)

    Lin, D. N. C.; Pringle, J. E.

    1987-01-01

    A model for treating the transfer of angular momentum within a gaseous differentially rotating disc subject to gravitational instability is discussed in terms of an effective kinematic viscosity. It is assumed that even when matter in the disc is subject to self-gravitation, the instability does not necessarily lead directly to condensation of parts of the disc into self-gravitating bodies. Conditions under which the present model permits a similarity solution are discussed, and it is shown that the general solution tends to the similarity solution at large times.

  16. Application of DTM for kerosene-alumina nanofluid flow and heat transfer between two rotating plates

    NASA Astrophysics Data System (ADS)

    Mahmoodi, M.; Kandelousi, Sh.

    2015-07-01

    In this paper, the differential transformation method (DTM) is applied to solve the governing equations of nanofluid flow and heat transfer between two parallel plates in a rotating system. The working fluid is a kerosene-alumina nanofluid. The influences of viscosity parameter, rotation parameter, nanoparticle volume fraction and Eckert number on the flow and heat transfer characteristics have been investigated. Results indicate that skin friction is a decreasing function of the viscosity and rotation parameters. Also it can be found that the Nusselt number has a direct relationship with the rotation parameter and the nanoparticle volume fraction while it has a reverse relationship with the viscosity parameter and the Eckert number.

  17. Drop Spreading with Random Viscosity

    NASA Astrophysics Data System (ADS)

    Xu, Feng; Jensen, Oliver

    2016-11-01

    Airway mucus acts as a barrier to protect the lung. However as a biological material, its physical properties are known imperfectly and can be spatially heterogeneous. In this study we assess the impact of these uncertainties on the rate of spreading of a drop (representing an inhaled aerosol) over a mucus film. We model the film as Newtonian, having a viscosity that depends linearly on the concentration of a passive solute (a crude proxy for mucin proteins). Given an initial random solute (and hence viscosity) distribution, described as a Gaussian random field with a given correlation structure, we seek to quantify the uncertainties in outcomes as the drop spreads. Using lubrication theory, we describe the spreading of the drop in terms of a system of coupled nonlinear PDEs governing the evolution of film height and the vertically-averaged solute concentration. We perform Monte Carlo simulations to predict the variability in the drop centre location and width (1D) or area (2D). We show how simulation results are well described (at much lower computational cost) by a low-order model using a weak disorder expansion. Our results show for example how variability in the drop location is a non-monotonic function of the solute correlation length increases. Engineering and Physical Sciences Research Council.

  18. Drop spreading with random viscosity

    NASA Astrophysics Data System (ADS)

    Xu, Feng; Jensen, Oliver E.

    2016-10-01

    We examine theoretically the spreading of a viscous liquid drop over a thin film of uniform thickness, assuming the liquid's viscosity is regulated by the concentration of a solute that is carried passively by the spreading flow. The solute is assumed to be initially heterogeneous, having a spatial distribution with prescribed statistical features. To examine how this variability influences the drop's motion, we investigate spreading in a planar geometry using lubrication theory, combining numerical simulations with asymptotic analysis. We assume diffusion is sufficient to suppress solute concentration gradients across but not along the film. The solute field beneath the bulk of the drop is stretched by the spreading flow, such that the initial solute concentration immediately behind the drop's effective contact lines has a long-lived influence on the spreading rate. Over long periods, solute swept up from the precursor film accumulates in a short region behind the contact line, allowing patches of elevated viscosity within the precursor film to hinder spreading. A low-order model provides explicit predictions of the variances in spreading rate and drop location, which are validated against simulations.

  19. Drop spreading with random viscosity

    PubMed Central

    2016-01-01

    We examine theoretically the spreading of a viscous liquid drop over a thin film of uniform thickness, assuming the liquid’s viscosity is regulated by the concentration of a solute that is carried passively by the spreading flow. The solute is assumed to be initially heterogeneous, having a spatial distribution with prescribed statistical features. To examine how this variability influences the drop’s motion, we investigate spreading in a planar geometry using lubrication theory, combining numerical simulations with asymptotic analysis. We assume diffusion is sufficient to suppress solute concentration gradients across but not along the film. The solute field beneath the bulk of the drop is stretched by the spreading flow, such that the initial solute concentration immediately behind the drop’s effective contact lines has a long-lived influence on the spreading rate. Over long periods, solute swept up from the precursor film accumulates in a short region behind the contact line, allowing patches of elevated viscosity within the precursor film to hinder spreading. A low-order model provides explicit predictions of the variances in spreading rate and drop location, which are validated against simulations. PMID:27843398

  20. Scientific Objectives of the Critical Viscosity Experiment

    NASA Technical Reports Server (NTRS)

    Berg, R. F.; Moldover, M. R.

    1993-01-01

    In microgravity, the Critical Viscosity Experiment will measure the viscosity of xenon 15 times closer to the critical point than is possible on earth. The results are expected to include the first direct observation of the predicted power-law divergence of viscosity in a pure fluid and they will test calculations of the value of the exponent associated with the divergence. The results, when combined with Zeno's decay-rate data, will strengthen the test of mode coupling theory. Without microgravity viscosity data, the Zeno test will require an extrapolation of existing 1-g viscosity data by as much as factor of 100 in reduced temperature. By necessity, the extrapolation would use an incompletely verified theory of viscosity crossover. With the microgravity viscosity data, the reliance on crossover models will be negligible allowing a more reliable extrapolation. During the past year, new theoretical calculations for the viscosity exponent finally achieved consistency with the best experimental data for pure fluids. This report gives the justification for the proposed microgravity Critical Viscosity Experiment in this new context. This report also combines for the first time the best available light scattering data with our recent viscosity data to demonstrate the current status of tests of mode coupling theory.

  1. The Effect of Variable Viscosities on Micropolar Flow of Two Nanofluids

    NASA Astrophysics Data System (ADS)

    Nadeem, S.; Ahmed, Z.; Saleem, S.

    2016-12-01

    A study of nanofluids is carried out that reveals the effect of rotational inertia and other physical parameters on the heat transfer and fluid flow. Temperature-dependent dynamic viscosity makes the microrotation viscosity parameter and the micro inertia density variant as well. The governing nonlinear partial differential equations are converted into a set of nonlinear ordinary differential equations by introducing suitable similarity transformations. These reduced nonlinear differential equations are then solved numerically by Keller-box method. The obtained numerical and graphical result discloses many interesting behaviour of nanofluids. It is seen that the temperature gradient decreases with the increase in viscosity parameter. Also, it is observed that with the fixed values of micropolar parameter and viscosity parameter, the velocity gradient near the wall increases with increasing values of solid particle volume fraction parameter. A suitable comparison of results is also presented in this study.

  2. Gas viscosity measurement with diamagnetic-levitation viscometer based on electromagnetically spinning system.

    PubMed

    Shimokawa, Y; Matsuura, Y; Hirano, T; Sakai, K

    2016-12-01

    Utilizing a graphite-disk probe attached with a thin aluminum disk, we have developed a friction-free viscosity measurement system. The probe is levitated above a NdFeB magnet because of diamagnetic effect and rotated by an electromagnetically induced torque. The probe is absolutely free form mechanical friction, and therefore, the accurate measurements of the viscosity of gases can be achieved. To demonstrate the accuracy and sensitivity of our method, we measured the viscosity of 8 kinds of gases and its temperature change from 278 K to 318 K, and we confirmed a good agreement between the obtained values and literature values. This paper demonstrates that our method has the ability to measure the fluid viscosity in the order of μPa ⋅ s.

  3. Gas viscosity measurement with diamagnetic-levitation viscometer based on electromagnetically spinning system

    NASA Astrophysics Data System (ADS)

    Shimokawa, Y.; Matsuura, Y.; Hirano, T.; Sakai, K.

    2016-12-01

    Utilizing a graphite-disk probe attached with a thin aluminum disk, we have developed a friction-free viscosity measurement system. The probe is levitated above a NdFeB magnet because of diamagnetic effect and rotated by an electromagnetically induced torque. The probe is absolutely free form mechanical friction, and therefore, the accurate measurements of the viscosity of gases can be achieved. To demonstrate the accuracy and sensitivity of our method, we measured the viscosity of 8 kinds of gases and its temperature change from 278 K to 318 K, and we confirmed a good agreement between the obtained values and literature values. This paper demonstrates that our method has the ability to measure the fluid viscosity in the order of μPa ṡ s.

  4. Effects of solid content and temperature on viscosity of tapioca meal.

    PubMed

    Adebowale, Abdul-Rasaq A; Sanni, Lateef O

    2013-06-01

    The effect of solid content (2.5-10%, w/v) and temperature (30-70°C) on the viscosity of tapioca meal from three cassava varieties was investigated in this study. Viscosity measurements were conducted using a digital rotational Brookfield viscometer. The viscosity of tapioca meal increased with increasing solid content and decreasing viscometer speeds. An empirical power-law equation fitted the viscosity data of the tapioca meals with correlation coefficients between 0.94 and 0.99. Our results indicated that tapioca meal can be characterized as a pseudo-plastic fluid and a mean value of 0.32 ± 0.18 was proposed as the power law index of tapioca meal from the three cassava varieties used in this study. Neither solid content, temperature nor shear rate altered the rheological characteristics of tapioca meal.

  5. Two-fluid simulations of the reversed-field pinch

    SciTech Connect

    Nebel, R.A.

    1990-01-01

    Two fluid and transport effects have recently been incorporated into the 3-D MHD code (Debs) originally developed by Schnack and coworkers. These include the Hall effect, diamagnetic drift effects, Braginskii viscosity and anisotropic thermal conduction. Incorporation of these effects required the development of new semi-implicit operators in order to provide numerical stability. Both anisotropic thermal conduction and parallel viscosity make the equations extremely stiff and require some care in formulation in order to avoid matrix conditioning problems. In general, these new concerns favor using simple isotropic operators (such as {nabla}{sup 2}) over the less dispersive but exact anisotropic semi-implicit operators. These numerical formulations will be discussed in detail. Accuracy and poisoning'' checks also will be presented. Results indicate that a number of new phenomena are present in these extended equations. For instance, the dynamo effect'' is seen to emerge from the Hall terms rather than the MHD terms if the viscosity is large. The observed relaxation is also much more robust than its MHD counterpart. Resistive wall instabilities are seen to lock nonlinearly to the wall if the edge viscosity is large but not to lock if the viscosity is small. Similarly, resistive g-modes are also very sensitive to the amount of viscosity present. The significant factor in all of these phenomena appears to be the parallel viscosity. 22 refs., 9 figs.

  6. A formula for the Shakura-Sunyaev turbulent viscosity parameter. [for modeling of accretion disks

    NASA Technical Reports Server (NTRS)

    Canuto, V. M.; Goldman, I.; Hubickyj, O.

    1984-01-01

    A formula for the Shakura-Suniaev alpha parameter is proposed in terms of the growth rate of the unstable modes of the physical mechanisms that generates turbulence. Turbulent convection is discussed as a particular example. The effect of rotation on turbulent viscosity is considered, and some remarks are made on convective fluxes, disk stability, and other types of instabilities.

  7. Mechanism and nature of the different viscosity sensitivities of hemicyanine dyes with various heterocycles.

    PubMed

    Cao, Jianfang; Hu, Chong; Liu, Fei; Sun, Wen; Fan, Jiangli; Song, Fengling; Sun, Shiguo; Peng, Xiaojun

    2013-06-03

    A series of hemicyanine derivatives are excellent fluorescent viscosity sensors in live cells and in imaging of living tissues due to their low quantum yields in solution but large fluorescence enhancements in viscous environments. Herein, three carbazole-based hemicyanine dyes with different heterocycles are studied. They have different background quantum yields, and hence different sensitivities to viscosity detection, large Stokes shifts, and high sensitivity. Better understanding of the structure-property relationships for viscosity sensitivity could benefit the design of improved dyes. Computational studies on these dyes reveal the mechanism of viscosity sensitivity of fluorescent molecular rotors and the nature of the difference in viscosity sensitivity of the three dyes. The results show that the greatly raised HOMO and greatly lowered LUMO in the S1 state compared with the S0 state are responsible for the large Stokes shift of the three dyes. The heterocyclic moieties have the primary influence on the LUMO levels of the three hemicyanine dyes. Rotation about the C-C bond adjacent to the carbazole moiety of the three dyes drives the molecule toward a small energy gap between the ground state and the first excited state, which causes mainly nonradiative deactivation. The oscillator strengths in the lowest singlet excited state drop rapidly with increasing rotation between 0 and 95°, which leads to a dark state for these dyes when fully twisted at 95°. We draw a mechanistic picture at the molecular level to illustrate how these dyes work as viscosity-sensitive fluorescent probes. The activation barriers and energy gaps of C-C bond rotation strongly depend on the choice of heterocycle, which plays a major role in reducing fluorescence quantum yield in the free state and provides high sensitivity to viscosity detection in viscous environments for the carbazole-based hemicyanine dyes.

  8. Effects of electron-cyclotron-resonance-heating-induced internal kink mode on the toroidal rotation in the KSTAR Tokamak.

    PubMed

    Seol, J; Lee, S G; Park, B H; Lee, H H; Terzolo, L; Shaing, K C; You, K I; Yun, G S; Kim, C C; Lee, K D; Ko, W H; Kwak, J G; Kim, W C; Oh, Y K; Kim, J Y; Kim, S S; Ida, K

    2012-11-09

    It is observed that the magnitude of the toroidal rotation speed is reduced by the central electron cyclotron resonance heating (ECRH) regardless of the direction of the toroidal rotation. The magnetohydrodynamics activities generally appear with the rotation change due to ECRH. It is shown that the internal kink mode is induced by the central ECRH and breaks the toroidal symmetry. When the magnetohydrodynamics activities are present, the toroidal plasma viscosity is not negligible. The observed effects of ECRH on the toroidal plasma rotation are explained by the neoclassical toroidal viscosity in this Letter. It is found that the neoclassical toroidal viscosity torque caused by the internal kink mode damps the toroidal rotation.

  9. Effective shear viscosity and dynamics of suspensions of micro-swimmers from small to moderate concentrations.

    SciTech Connect

    Gyrya, V.; Lipnikov, K.; Aranson, I.; Berlyand, L.

    2011-05-01

    Recently, there has been a number of experimental studies convincingly demonstrating that a suspension of self-propelled bacteria (microswimmers in general) may have an effective viscosity significantly smaller than the viscosity of the ambient fluid. This is in sharp contrast with suspensions of hard passive inclusions, whose presence always increases the viscosity. Here we present a 2D model for a suspension of microswimmers in a fluid and analyze it analytically in the dilute regime (no swimmer-swimmer interactions) and numerically using a Mimetic Finite Difference discretization. Our analysis shows that in the dilute regime (in the absence of rotational diffusion) the effective shear viscosity is not affected by self-propulsion. But at the moderate concentrations (due to swimmer-swimmer interactions) the effective viscosity decreases linearly as a function of the propulsion strength of the swimmers. These findings prove that (i) a physically observable decrease of viscosity for a suspension of self-propelled microswimmers can be explained purely by hydrodynamic interactions and (ii) self-propulsion and interaction of swimmers are both essential to the reduction of the effective shear viscosity. We also performed a number of numerical experiments analyzing the dynamics of swimmers resulting from pairwise interactions. The numerical results agree with the physically observed phenomena (e.g., attraction of swimmer to swimmer and swimmer to the wall). This is viewed as an additional validation of the model and the numerical scheme.

  10. Effective shear viscosity and dynamics of suspensions of micro-swimmers from small to moderate concentrations.

    PubMed

    Gyrya, V; Lipnikov, K; Aranson, I S; Berlyand, L

    2011-05-01

    Recently, there has been a number of experimental studies convincingly demonstrating that a suspension of self-propelled bacteria (microswimmers in general) may have an effective viscosity significantly smaller than the viscosity of the ambient fluid. This is in sharp contrast with suspensions of hard passive inclusions, whose presence always increases the viscosity. Here we present a 2D model for a suspension of microswimmers in a fluid and analyze it analytically in the dilute regime (no swimmer-swimmer interactions) and numerically using a Mimetic Finite Difference discretization. Our analysis shows that in the dilute regime (in the absence of rotational diffusion) the effective shear viscosity is not affected by self-propulsion. But at the moderate concentrations (due to swimmer-swimmer interactions) the effective viscosity decreases linearly as a function of the propulsion strength of the swimmers. These findings prove that (i) a physically observable decrease of viscosity for a suspension of self-propelled microswimmers can be explained purely by hydrodynamic interactions and (ii) self-propulsion and interaction of swimmers are both essential to the reduction of the effective shear viscosity. We also performed a number of numerical experiments analyzing the dynamics of swimmers resulting from pairwise interactions. The numerical results agree with the physically observed phenomena (e.g., attraction of swimmer to swimmer and swimmer to the wall). This is viewed as an additional validation of the model and the numerical scheme.

  11. Elements of Neoclassical Theory and Plasma Rotation in a Tokamak

    NASA Astrophysics Data System (ADS)

    Smolyakov, A.

    2015-12-01

    The following sections are included: * Introduction * Quasineutrality condition * Diffusion in fully ionized magnetized plasma and automatic ambipolarity * Toroidal geometry and neoclassical diffusion * Diffusion and ambipolarity in toroidal plasmas * Ambipolarity and equilibrium poloidal rotation * Ambipolarity paradox and damping of poloidal rotation * Neoclassical plasma inertia * Oscillatory modes of poloidal plasma rotation * Dynamics of the toroidal momentum * Momentum diffusion in strongly collisional, short mean free path regime * Diffusion of toroidal momentum in the weak collision (banana) regime * Toroidal momentum diffusion and momentum damping from drift-kinetic theory and fluid moment equations * Comments on non-axisymmetric effects * Summary * Acknowledgments * Appendix: Trapped (banana) particles and collisionality regimes in a tokamak * Appendix: Hierarchy of moment equations * Appendix: Plasma viscosity tensor in the magnetic field: parallel viscosity, gyroviscosity, and perpendicular viscosity * Appendix: Closure relations for the flux surface averaged parallel viscosity in neoclassical (banana and plateau) regimes * References

  12. NMR of biomolecules in low viscosity, liquid CO 2

    NASA Astrophysics Data System (ADS)

    Gaemers, Sander; Elsevier, Cornelis J.; Bax, Ad

    1999-02-01

    We demonstrate that hetero- and homonuclear NMR spectra of cyclosporin A and pancreatic trypsin inhibitor (BPTI) can be recorded at room temperature in liquid CO 2, a medium of very low viscosity, which has been reported to have no adverse effect on molecular structure or activity of several proteins. Rotational diffusion of cyclosporin A in a CO 2/methanol mixture is approximately three-fold faster than in chloroform. Translational diffusion for BPTI, dissolved in liquid CO 2 by co-adding detergent and trifluoroethanol, is measured to be faster than in water, but rotational diffusion is not. Development of improved detergents is anticipated to make feasible the encapsulation of most biological macromolecules in water-containing reverse micelles, which can be suspended in a wide array of apolar, supercritical or near-critical solvents.

  13. Viscosity dictates metabolic activity of Vibrio ruber

    PubMed Central

    Borić, Maja; Danevčič, Tjaša; Stopar, David

    2012-01-01

    Little is known about metabolic activity of bacteria, when viscosity of their environment changes. In this work, bacterial metabolic activity in media with viscosity ranging from 0.8 to 29.4 mPas was studied. Viscosities up to 2.4 mPas did not affect metabolic activity of Vibrio ruber. On the other hand, at 29.4 mPas respiration rate and total dehydrogenase activity increased 8 and 4-fold, respectively. The activity of glucose-6-phosphate dehydrogenase (GPD) increased up to 13-fold at higher viscosities. However, intensified metabolic activity did not result in faster growth rate. Increased viscosity delayed the onset as well as the duration of biosynthesis of prodigiosin. As an adaptation to viscous environment V. ruber increased metabolic flux through the pentose phosphate pathway and reduced synthesis of a secondary metabolite. In addition, V. ruber was able to modify the viscosity of its environment. PMID:22826705

  14. Saybolt universal viscosity converted to kinematic

    SciTech Connect

    Anaya, C.; Bermudez, O.

    1987-09-21

    This article describes a program for personal and handheld computers, written in Basic, which has been developed for the conversion of Saybolt universal viscosity in Saybolt Universal Seconds (SSU or SUS) to kinematic viscosity in centistokes (cSt), at any selected temperature. It was developed using the mathematical relationship presented in the American Society for Testing and Materials (ASTM) standard D2161-82. In the standard, an equation is presented to convert kinematic viscosity to Saybolt universal viscosity, but nothing is presented to convert from Saybolt to kinematic because it is necessary to find the roots of a nonexplicit function. There are several numerical methods that can be used to determine the roots of the nonexplicit function, and therefore, convert Saybolt universal viscosity to kinematic viscosity. In the program, the first iteration of the second-order Newton-Raphson method is followed by the Wegstein method as a convergence accelerator.

  15. Rotational testing.

    PubMed

    Furman, J M

    2016-01-01

    The natural stimulus for the semicircular canals is rotation of the head, which also might stimulate the otolith organs. Vestibular stimulation usually induces eye movements via the vestibulo-ocular reflex (VOR). The orientation of the subject with respect to the axis of rotation and the orientation of the axis of rotation with respect to gravity together determine which labyrinthine receptors are stimulated for particular motion trajectories. Rotational testing usually includes the measurement of eye movements via a video system but might use a subject's perception of motion. The most common types of rotational testing are whole-body computer-controlled sinusoidal or trapezoidal stimuli during earth-vertical axis rotation (EVAR), which stimulates primarily the horizontal semicircular canals bilaterally. Recently, manual impulsive rotations, known as head impulse testing (HIT), have been developed to assess individual horizontal semicircular canals. Most types of rotational stimuli are not used routinely in the clinical setting but may be used in selected research environments. This chapter will discuss clinically relevant rotational stimuli and several types of rotational testing that are used primarily in research settings.

  16. Transient Torque Method: A Fast and Nonintrusive Technique to Simultaneously Determine Viscosity and Electrical Conductivity of Semiconducting and Metallic Melts

    NASA Technical Reports Server (NTRS)

    Li, C.; Ban, H.; Lin, B.; Scripa, R. N.; Su, C.-H.; Lehoczky, S. L.; Zhu, S.

    2004-01-01

    A transient torque method was developed to rapidly and simultaneously determine the viscosity and electrical conductivity of liquid metals and molten semiconductors. The experimental setup of the transient torque method is similar to that of the oscillation cup method. The melt sample is sealed inside a fused silica ampoule, and the ampoule is suspended by a long quartz fiber to form a torsional oscillation system. A rotating magnetic field is used to induce a rotating flow in the conductive melt, which causes the ampoule to rotate around its vertical axis. A sensitive angular detector is used to measure the deflection angle of the ampoule. Based on the transient behavior of the deflection angle as the rotating magnetic field is applied, the electrical conductivity and viscosity of the melt can be obtained simultaneously by numerically fitting the data to a set of governing equations. The transient torque viscometer was applied successfully to measure the viscosity and electrical conductivity of high purity mercury at 53.4 C. The results were in excellent agreement with published data. The method is nonintrusive; capable of rapid measurement of the viscosity of toxic, high vapor pressure melts at elevated temperatures. In addition, the transient torque viscometer can also be operated as an oscillation cup viscometer to measure just the viscosity of the melt or as a rotating magnetic field method to determine the electrical conductivity of a melt or a solid if desired.

  17. Bacterial accumulation in viscosity gradients

    NASA Astrophysics Data System (ADS)

    Waisbord, Nicolas; Guasto, Jeffrey

    2016-11-01

    Cell motility is greatly modified by fluid rheology. In particular, the physical environments in which cells function, are often characterized by gradients of viscous biopolymers, such as mucus and extracellular matrix, which impact processes ranging from reproduction to digestion to biofilm formation. To understand how spatial heterogeneity of fluid rheology affects the motility and transport of swimming cells, we use hydrogel microfluidic devices to generate viscosity gradients in a simple, polymeric, Newtonian fluid. Using video microscopy, we characterize the random walk motility patterns of model bacteria (Bacillus subtilis), showing that both wild-type ('run-and-tumble') cells and smooth-swimming mutants accumulate in the viscous region of the fluid. Through statistical analysis of individual cell trajectories and body kinematics in both homogeneous and heterogeneous viscous environments, we discriminate passive, physical effects from active sensing processes to explain the observed cell accumulation at the ensemble level.

  18. Z-Pinch fusion-based nuclear propulsion

    NASA Astrophysics Data System (ADS)

    Miernik, J.; Statham, G.; Fabisinski, L.; Maples, C. D.; Adams, R.; Polsgrove, T.; Fincher, S.; Cassibry, J.; Cortez, R.; Turner, M.; Percy, T.

    2013-02-01

    Fusion-based nuclear propulsion has the potential to enable fast interplanetary transportation. Due to the great distances between the planets of our solar system and the harmful radiation environment of interplanetary space, high specific impulse (Isp) propulsion in vehicles with high payload mass fractions must be developed to provide practical and safe vehicles for human space flight missions. The Z-Pinch dense plasma focus method is a Magneto-Inertial Fusion (MIF) approach that may potentially lead to a small, low cost fusion reactor/engine assembly [1]. Recent advancements in experimental and theoretical understanding of this concept suggest favorable scaling of fusion power output yield [2]. The magnetic field resulting from the large current compresses the plasma to fusion conditions, and this process can be pulsed over short timescales (10-6 s). This type of plasma formation is widely used in the field of Nuclear Weapons Effects testing in the defense industry, as well as in fusion energy research. A Z-Pinch propulsion concept was designed for a vehicle based on a previous fusion vehicle study called "Human Outer Planet Exploration" (HOPE), which used Magnetized Target Fusion (MTF) [3] propulsion. The reference mission is the transport of crew and cargo to Mars and back, with a reusable vehicle. The analysis of the Z-Pinch MIF propulsion system concludes that a 40-fold increase of Isp over chemical propulsion is predicted. An Isp of 19,436 s and thrust of 3812 N s/pulse, along with nearly doubling the predicted payload mass fraction, warrants further development of enabling technologies.

  19. Fast Z - Pinch Study in Russia and Related Problems

    NASA Astrophysics Data System (ADS)

    Grabovskii, E. V.

    2002-12-01

    The fast Z pinches are considered as a perspective source of powerful soft x-ray emission for the ICF pellet ignition. The physical phenomena which take place in process fast of Z-pinch implosion are under investigation in the TRINITI (Troisk), in the RSC Kurchatov Institute (KI, Moscow) and the HCEI (Tomsk). In the KI the possibility of terawatt electrical power transfer in small volume hohlraum during nanosecond time duration is studied. In the TRINITI the physics of multi wire arrays implosion, the rate of plasma production in current-driven wire arrays, the conversion of pulsed power energy into x-ray emission are studied. In the HCEI (Tomsk) the stability of double gas puff implosion and the influence of gas puff regime and current pulse duration on the implosion and emitted x-ray spectrum are under investigation. The HCEI develops the new components of pulse power multi spark switches and the generators of impulse currents (LTD) with duration of an energy supply less than 100 ns. As available way to get the pulsed power generator with multi tens megaampere current the joint team of scientists from the laboratories of the TRINITI, the Efremov Institute, RFNC VNIITF (Snezinsk) have developed the concept of the Baikal facility. The KI designs, creates and tests the plasma erosion switches for the module of the Baikal facility. The inductive storage, the systems of magnetic field compression and the explosive open switches are developed in the TRINITI and the Efremov Institute. The development of new design of the pulse power generators and physics of fast Z-pinch implosion aims to create next advanced generation of powerful driver for ICF.

  20. Theta-Pinch Thruster for Piloted Deep Space Exploration

    NASA Technical Reports Server (NTRS)

    LaPointe, Mike R.; Reddy, Dhanireddy (Technical Monitor)

    2000-01-01

    A new high-power propulsion concept that combines a rapidly pulsed theta-pinch discharge with upstream particle reflection by a magnetic mirror was evaluated under a Phase 1 grant awarded through the NASA Institute for Advanced Concepts. Analytic and numerical models were developed to predict the performance of a theta-pinch thruster operated over a wide range of initial gas pressures and discharge periods. The models indicate that a 1 m radius, 10 m long thruster operated with hydrogen propellant could provide impulse-bits ranging from 1 N-s to 330 N-s with specific impulse values of 7,500 s to 2,500 s, respectively. A pulsed magnetic field strength of 2 T is required to compress and heat the preionized hydrogen over a 10(exp -3) second discharge period, with about 60% of the heated plasma exiting the chamber each period to produce thrust. The unoptimized thruster efficiency is low, peaking at approximately 16% for an initial hydrogen chamber pressure of 100 Torr. The specific impulse and impulse-bit at this operating condition are 3,500 s and 90 N-s, respectively, and the required discharge energy is approximately 9x10(exp 6) J. For a pulse repetition rate of 10 Hz, the engine would produce an average thrust of 900 N at 3,500 s specific impulse. Combined with the electrodeless nature of the device, these performance parameters indicate that theta-pinch thrusters could provide unique, long-life propulsion systems for piloted deep space mission applications.

  1. Liner Compression of a MAGO / Inverse-Pinch Configuration

    SciTech Connect

    Siemon, R E; Atchison, W L; Awe, T; Bauer, B S; Buyko, A M; Chernyshev, V K; Cowan, T E; Degnan, J H; Faehl, R J; Fuelling, S; Garanin, S F; Goodrich, T; Ivanovsky, A V; Lindemuth, I R; Makhin, V; Mokhov, V N; Reinovsky, R E; Ryutov, D D; Scudder, D W; Taylor, T; Yakubov, V B

    2005-05-18

    In the ''metal liner'' approach to Magnetized Target Fusion (MTF), a preheated magnetized plasma target is compressed to thermonuclear temperature and high density by externally driving the implosion of a flux conserving metal enclosure, or liner, which contains the plasma target. As in inertial confinement fusion, the principle fusion fuel heating mechanism is pdV work by the imploding enclosure, called a pusher in ICF. One possible MTF target, the hard-core diffuse z pinch, has been studied in MAGO experiments at VNIIEF, and is one possible target being considered for experiments on the Atlas pulsed power facility. Numerical MHD simulations show two intriguing and helpful features of the diffuse z pinch with respect to compressional heating. First, in two-dimensional simulations the m=0 interchange modes, arising from an unstable pressure profile, result in turbulent motions and self-organization into a stable pressure profile. The turbulence also gives rise to convective thermal transport, but the level of turbulence saturates at a finite level, and simulations show substantial heating during liner compression despite the turbulence. The second helpful feature is that pressure profile evolution during compression tends towards improved stability rather than instability when analyzed according to the Kadomtsev criteria. A liner experiment is planned for Atlas to study compression of magnetic flux without plasma as a first step. The Atlas geometry is compatible with a diffuse z pinch, and simulations of possible future experiments show that keV temperatures and useful neutron production for diagnostic purposes should be possible if a suitable plasma injector is added to the Atlas facility.

  2. Universal pinch off of rods by capillarity-driven surface diffusion

    SciTech Connect

    Wong, H.; Miksis, M.J.; Voorhees, P.W.; Davis, S.H.

    1998-06-05

    Interfacial energy is a central factor in setting the morphology of phases and in determining the stability of equilibrium morphologies. here the authors examine the morphological evolution of a rod via capillary-driven surface diffusion as it both approaches and departs the topological singularity of pinch off. During the final stages of pinching the neck radius approaches zero, and self-similar solutions are sought. The authors have derived local similarity solutions for the axisymmetric pinch off of rods when the morphological evolution is by capillarity-driven surface diffusion. These local solutions describe the approach to and departure from the topological singularity where a rod pinches into two separate bodies. During pinching, the self-similar surface profile far away from the neck approaches two opposing cones with a unique half-cone angle of 46.04{degree}. It is thus likely that all rods must pinch off with this cone angle. This assertion is supported by several numerical simulations. After pinch off, the smoothening of the cone tip is again self-similar. The results obtained here for rods also apply to the pinch off of cylindrical pore channels.

  3. Miniaturization of pinch-type valves and pumps for practical micro total analysis system integration

    NASA Astrophysics Data System (ADS)

    Oh, Kwang W.; Rong, Rong; Ahn, Chong H.

    2005-12-01

    In this paper, to address the issues relevant to leakage, dead volume and contamination, we have miniaturized a pinch-type valve and a pinch-type peristaltic pump, which are surface mountable on the microfluidic lab-on-a-chip (LOC) devices. The pinch-type valve consisted of a solenoid magnetic actuator with a pinch plunger and a biomedical grade silicone tube. The pinch valve has shown excellent characteristics of no detectable leakage flow up to 200 kPa and zero dead volume, keeping its surface mountable capability over the microfluidic devices. Furthermore, the new pinch-type peristaltic pump realized by connecting three pinch-type valves in series has shown self-priming and bi-directional pumping capabilities. The pump enabled a wide pumping rate control over 33:1 from 30 µl min-1 at 0.4 Hz up to 1000 µl min-1 at 100 Hz. Back pressure of the pump was 280 cm of water pressure at 20 Hz, equivalent to 27.6 kPa. As a result, the miniaturized stand-alone pinch-type valve and pump developed in this work will have many practical applications in miniaturized total analysis systems (μ-TAS).

  4. High-energy electron acceleration in the gas-puff Z-pinch plasma

    NASA Astrophysics Data System (ADS)

    Takasugi, Keiichi; Miyazaki, Takanori; Nishio, Mineyuki

    2014-12-01

    The characteristics of hard x-ray generation were examined in the gas-puff z-pinch experiment. The experiment on reversing the voltage was conducted. In both of the positive and negative discharges, the x-ray was generated only from the anode surface, so it was considered that the electrons were accelerated by the induced electromagnetic force at the pinch time.

  5. High-energy electron acceleration in the gas-puff Z-pinch plasma

    SciTech Connect

    Takasugi, Keiichi; Miyazaki, Takanori; Nishio, Mineyuki

    2014-12-15

    The characteristics of hard x-ray generation were examined in the gas-puff z-pinch experiment. The experiment on reversing the voltage was conducted. In both of the positive and negative discharges, the x-ray was generated only from the anode surface, so it was considered that the electrons were accelerated by the induced electromagnetic force at the pinch time.

  6. Anomalous current pinch of a toroidal axisymmetric plasma with stochastic magnetic field perturbations

    SciTech Connect

    Wang, Shaojie

    2016-07-15

    Anomalous current pinch, in addition to the anomalous diffusion due to stochastic magnetic perturbations, is theoretically found, which may qualitatively explain the recent DIII-D experiment on resonant magnetic field perturbation. The anomalous current pinch, which may resolve the long-standing issue of seed current in a fully bootstrapped tokamak, is also discussed for the electrostatic turbulence.

  7. Turbulence, flow and transport: hints from reversed field pinch

    NASA Astrophysics Data System (ADS)

    Vianello, N.; Antoni, V.; Spada, E.; Spolaore, M.; Serianni, G.; Cavazzana, R.; Bergsåker, H.; Cecconello, M.; Drake, J. R.

    2006-04-01

    The interplay between sheared E × B flows and turbulence has been experimentally investigated in the edge region of the Extrap-T2R reversed field pinch experiment. Electrostatic fluctuations are found to rule the momentum balance equation representing the main driving term for sheared flows which counterbalances anomalous viscous damping. The driving role of electrostatic fluctuations is proved by the spatial structure of the Reynolds stress and by the time behaviour of the mean energy production term which supports the existence of an energy exchange from the small scales of turbulence to the larger scales of the mean flow.

  8. Dynamo and anomalous transport in the reversed field pinch

    SciTech Connect

    Prager, S.C.

    1998-08-01

    The reversed field pinch is an effective tool to study the macroscopic consequences of magnetic fluctuations, such as the dynamo effect and anomalous transport. Several explanations exist for the dynamo (the self-generation of plasma current)--the MHD dynamo, the kinetic dynamo, and the diamagnetic dynamo. There is some experimental evidence for each, particularly from measurements of ion velocity and electron pressure fluctuations. Magnetic fluctuations are known to produce energy and particle flux in the RFP core. Current profile control is able to decrease fluctuation-induced transport by a factor of five. Improved confinement regimes are also obtained at deep reversal and, possibly, with flow shear.

  9. Stability of a diffuse linear pinch with axial boundaries

    NASA Technical Reports Server (NTRS)

    Einaudi, G.; Van Hoven, G.

    1981-01-01

    A formulation of the stability behavior of a finite-length pinch is presented. A general initial perturbation is expressed as a uniformly convergent sum over a complete discrete k set. A variational calculation is then performed, based on the energy principle, in which the end-boundary conditions appear as constraints. The requisite Lagrange multipliers mutually couple the elemental periodic excitations. The resulting extended form of delta-W still admits a proper second-variation treatment so that the minimization and stability considerations of Newcomb remain applicable. Comparison theorems are discussed as is the relevance of this end-effect model to the stability of solar coronal loops.

  10. Axisymmetric bubble pinch-off at high Reynolds numbers.

    PubMed

    Gordillo, J M; Sevilla, A; Rodríguez-Rodríguez, J; Martínez-Bazán, C

    2005-11-04

    Analytical considerations and potential-flow numerical simulations of the pinch-off of bubbles at high Reynolds numbers reveal that the bubble minimum radius, rn, decreases as tau proportional to r2n sqrt[1lnr2n], where tau is the time to break up, when the local shape of the bubble near the singularity is symmetric. However, if the gas convective terms in the momentum equation become of the order of those of the liquid, the bubble shape is no longer symmetric and the evolution of the neck changes to a rn proportional to tau1/3 power law. These findings are verified experimentally.

  11. Pinch-Reflex-Diode Scaling on the Aurora Pulser.

    DTIC Science & Technology

    1982-06-29

    Goldstein and Roswell Lee, Phys. Rev. Lett. 35, 1079 (1975). 9. C.W. Mendel, Jr., D.M. Zagar , G.S. Mills, S . Humphries, Jr., and * S.A. Goldstein, Rev...4116 4. TITLE (and Subtitl.) S . TYPE OF REPORT & PERIOD COVERED PINCH-REFLEX-DIODE SCALING ON THE Interim report on a continuing AURORA PULSER NRL...problem. 6. PERFORMING ORG. REPORT NUMBER 7. AUTHOR() 6. CONTRACT OR GRANT NUMBER(A) R. A. Meger* and F. C. Young S . PERFORMING ORGANIZATION NAME AND

  12. Dynamical processes in the reversed-field pinch

    SciTech Connect

    Caramana, E.; Cayton, T.; Dagazian, R.

    1982-01-01

    This paper presents a review of recent theoretical work on the Reversed-Field Pinch (RFP) at Los Alamos National Laboratory. A wide variety of topics are discussed. These include: nonlinear, two-dimensional, helical, magnetohydrodynamic (MHD) simulations of current-driven modes; a statistical model of plasma turbulence in the RFP; analytic and numerical calculations of resistive ballooning modes in toroidal geometry; work on coherent m = 0 excitations observed in the ZT-40M device; finite Larmor radius effects on the tearing mode; destabilization of MHD modes by kinetic effects; and, possible plasma heating by means of magnetoacoustic oscillations.

  13. Collision and average velocity effects on the ratchet pinch

    SciTech Connect

    Vlad, M.; Benkadda, S.

    2008-03-15

    A ratchet-type average velocity V{sup R} appears for test particles moving in a stochastic potential and a magnetic field that is space dependent. This model is developed by including particle collisions and an average velocity. We show that these components of the motion can destroy the ratchet velocity but they also can produce significant increase of V{sup R}, depending on the parameters. The amplification of the ratchet pinch is a nonlinear effect that appears in the presence of trajectory eddying.

  14. Solid fiber Z-pinches: ''Cold-start'' computations

    SciTech Connect

    Lindemuth, I.R.

    1989-01-01

    One- and two-dimensional magnetohydrodynamic computations have been performed to study the behavior of solid deuterium fiber Z-pinch experiments performed at Los Alamos and the Naval Research Laboratory. The computations use a tabulated atomic data base and ''cold-start'' initial conditions. The computations predict that the solid fiber persists longer in existing experiments than previously expected and that the discharge actually consists of a relatively low-density, hot plasma which has been ablated from the fiber. The computations exhibit m = 0 behavior in the hot, exterior plasma prior to complete ablation of the solid fiber. The m = 0 behavior enhances the fiber ablation rate. 10 refs., 5 figs.

  15. TPE-1R (M) reversed field pinch experiment

    SciTech Connect

    Shimada, T.; Hirano, Y.; Maejima, Y.; Ogawa, K.

    1981-01-01

    This report describes the engineering aspects of the design, tests, and performances of the toroidal device TPE-1RM with which plasma physics researches on ''Reversed Field Pinch''configurations are carried out and this is an intermediate scale like HBTX-1A, ZT-40M, and ETA-BETA II. In TPE-1RM experiments are being performed in order to obtain an optimum reversed field configurations for MHD stability. The main description in this report is devoted to the metal vacuum vessel and specially contrived electrical circuit for field programming control techniques. The experiments with this device have been successful both from the technical and physcial points of view.

  16. The experimental viscosity and calculated relative viscosity of liquid In Sn allcoys

    NASA Astrophysics Data System (ADS)

    Wu, A. Q.; Guo, L. J.; Liu, C. S.; Jia, E. G.; Zhu, Z. G.

    2007-04-01

    The experimental measured viscosity of liquid pure Sn, In 20Sn 80 and In 80Sn 20 alloys was studied, and to make a comparison, the calculated relative viscosity based on the pair distribution functions, g( r), has also been studied. There is one peak in each experimental viscosity and calculated relative-viscosity curve of liquid pure Sn about 1000 °C. One valley appears in each experimental viscosity and calculated viscosity curve of liquid In 20Sn 80 alloy about 700 °C. There is no abnormal behavior on In 80Sn 20 alloy. The behavior of experimental viscosity and calculated relative viscosity is coincident with each other. Those results conformed that the temperature-induced structure anomalies reported before did take place.

  17. Viscosity modification of high-oleic sunflower oil with polymeric additives for the design of new biolubricant formulations.

    PubMed

    Quinchia, L A; Delgado, M A; Valencia, C; Franco, J M; Gallegos, C

    2009-03-15

    Although most common lubricants contain mineral or synthetic oils as basestocks, new environmental regulations are demanding environmentally friendly lubricants. In this sense, vegetable oils represent promising alternatives to mineral-based lubricants because of their high biodegradability, good lubricity, and low volatility. However, their poor thermooxidative stability and the small range of viscosity represent a clear disadvantage to be used as suitable biolubricants. The main objective of this work was to develop new environmentally friendly lubricant formulations with improved kinematic viscosity values and viscosity thermal susceptibility. With this aim, a high-oleic sunflower oil (HOSO) was blended with polymeric additives, such as ethylene vinyl acetate (EVA) and styrene-butadiene-styrene (SBS) copolymers, at different concentrations (0.5-5% w/w). Dynamic viscosity and density measurements were performed in a rotational rheometer and capillary densimeter, respectively, in a temperature range between 25 and 120 degrees C. An Arrhenius-like equation fits the evolution of viscosity with temperature fairly well. Both EVA and SBS copolymers may be satisfactorily used as additives to increase the viscosity of HOSO, thus improving the low viscosity values of this oil. HOSO viscosity increases with polymer concentration. Specifically, EVA/HOSO blends exhibit higher viscosity values, which are needed for applications such as lubrication of bearings and four-stroke engines. On the other hand, viscositythermal susceptibility of HOSO samples increases with EVA or SBS concentration.

  18. Overview of the Fusion Z-Pinch Experiment FuZE

    NASA Astrophysics Data System (ADS)

    Weber, T. R.; Shumlak, U.; Nelson, B. A.; Golingo, R. P.; Claveau, E. L.; McLean, H. S.; Tummel, K. K.; Higginson, D. P.; Schmidt, A. E.; UW/LLNL Team

    2016-10-01

    Previously, the ZaP device, at the University of Washington, demonstrated sheared flow stabilized (SFS) Z-pinch plasmas. Instabilities that have historically plagued Z-pinch plasma confinement were mitigated using sheared flows generated from a coaxial plasma gun of the Marshall type. Based on these results, a new SFS Z-pinch experiment, the Fusion Z-pinch Experiment (FuZE), has been constructed. FuZE is designed to investigate the scaling of SFS Z-pinch plasmas towards fusion conditions. The experiment will be supported by high fidelity physics modeling using kinetic and fluid simulations. Initial plans are in place for a pulsed fusion reactor following the results of FuZE. Notably, the design relies on proven commercial technologies, including a modest discharge current (1.5 MA) and voltage (40 kV), and liquid metal electrodes. Supported by DoE FES, NNSA, and ARPA-E ALPHA.

  19. Bubble pinch-off and scaling during liquid drop impact on liquid pool

    NASA Astrophysics Data System (ADS)

    Ray, Bahni; Biswas, Gautam; Sharma, Ashutosh

    2012-08-01

    Simulations are performed to show entrapment of air bubble accompanied by high speed upward and downward water jets when a water drop impacts a pool of water surface. A new bubble entrapment zone characterised by small bubble pinch-off and long thick jet is found. Depending on the bubble and jet behaviour, the bubble entrapment zone is subdivided into three sub-regimes. The entrapped bubble size and jet height depends on the crater shape and its maximum depth. During the bubble formation, bubble neck develops an almost singular shape as it pinches off. The final pinch-off shape and the power law governing the pinching, rneck ∝ A(t0 - t)αvaries with the Weber number. Weber dependence of the function describing the radius of the bubble during the pinch-off only affects the coefficient A and not the power exponent α.

  20. Feedback stabilization of resistive wall modes in a reversed-field pinch

    NASA Astrophysics Data System (ADS)

    Brunsell, P. R.; Yadikin, D.; Gregoratto, D.; Paccagnella, R.; Liu, Y. Q.; Cecconello, M.; Drake, J. R.; Manduchi, G.; Marchiori, G.

    2005-09-01

    An array of saddle coils having Nc=16 equally spaced positions along the toroidal direction has been installed for feedback control of resistive wall modes (RWMs) on the EXTRAP T2R reversed-field pinch [P. R. Brunsell, H. Bergsaker, M. Cecconello et al., Plasma Phys. Controlled Fusion 43, 1457 (2001)]. Using feedback, multiple nonresonant RWMs are simultaneously suppressed for three to four wall times. Feedback stabilization of RWMs results in a significant prolongation of the discharge duration. This is linked to a better sustainment of the plasma and tearing mode toroidal rotation with feedback. Due to the limited number of coils in the toroidal direction, pairs of modes with toroidal mode numbers n ,n' that fulfill the condition ∣n-n'∣=Nc are coupled by the feedback action from the discrete coil array. With only one unstable mode in a pair of coupled modes, the suppression of the unstable mode is successful. If two modes are unstable in a coupled pair, two possibilities exist: partial suppression of both modes or, alternatively, complete stabilization of one target mode while the other is left unstable.

  1. Reversed field pinch operation with intelligent shell feedback control in EXTRAP T2R

    NASA Astrophysics Data System (ADS)

    Brunsell, P. R.; Kuldkepp, M.; Menmuir, S.; Cecconello, M.; Hedqvist, A.; Yadikin, D.; Drake, J. R.; Rachlew, E.

    2006-11-01

    Discharges in the thin shell reversed field pinch (RFP) device EXTRAP T2R without active feedback control are characterized by growth of non-resonant m = 1 unstable resistive wall modes (RWMs) in agreement with linear MHD theory. Resonant m = 1 tearing modes (TMs) exhibit initially fast rotation and the associated perturbed radial fields at the shell are small, but eventually TMs wall-lock and give rise to a growing radial field. The increase in the radial field at the wall due to growing RWMs and wall-locked TMs is correlated with an increase in the toroidal loop voltage, which leads to discharge termination after 3-4 wall times. An active magnetic feedback control system has been installed in EXTRAP T2R. A two-dimensional array of 128 active saddle coils (pair-connected into 64 independent m = 1 coils) is used with intelligent shell feedback control to suppress the m = 1 radial field at the shell. With feedback control, active stabilization of the full toroidal spectrum of 16 unstable m = 1 non-resonant RWMs is achieved, and TM wall locking is avoided. A three-fold extension of the pulse length, up to the power supply limit, is observed. Intelligent shell feedback control is able to maintain the plasma equilibrium for 10 wall times, with plasma confinement parameters sustained at values comparable to those obtained in thick shell devices of similar size.

  2. Edge fluctuations in the MST (Madison Symmetric Torus) reversed field pinch

    SciTech Connect

    Almagri, A.; Assadi, S.; Beckstead, J.; Chartas, G.; Crocker, N.; Den Hartog, D.; Dexter, R.; Hokin, S.; Holly, D.; Nilles, E.; Prager, S.; Rempel, T.; Sarff, J.; Scime, E.; Shen, W.; Spragins, C.; Sprott, J.; Starr, G.; Stoneking, M.; Watts, C.

    1990-10-01

    Edge magnetic and electrostatic fluctuations are measured in the Madison Symmetric Torus (MST) reversed field pinch. At low frequency (<25 kHz), the mode number spectra of magnetic fluctuations agree very well with theoretical prediction for nonlinearly saturated tearing fluctuations resonant in the core. At high frequency (50 kHz to 100 kHz) the magnetic spectra broaden and the modes become resonant in the reversal region. Nonlinear phenomena are under experimental investigation. The low frequency fluctuations phase-lock together to produce a rotating localized disturbance. Bi-spectral analysis in frequency also reveals nonlinear three-wave mode-coupling at low frequency. Electrostatic fluctuations are substantial and do not appear to obey a Boltzmann relation (i.e. e{tilde {phi}}/kT{sub e} > {tilde p}{sub e}/p{sub e} where {tilde {phi}} and {tilde p}{sub e} are the fluctuating potential and pressure, respectively). From measurements of the fluctuating density, temperature, and potential we infer that the electrostatic fluctuation induced transport of particles and energy can be substantial. 13 refs., 11 figs.

  3. MHD stability properties of a line-tied linear screw pinch plasma

    NASA Astrophysics Data System (ADS)

    Bergerson, William; Forest, C. B.; Fiksel, G.; Grierson, B.; Hannum, D.; Hegna, C.; Kendrick, R.; Oliva, S.; Sarff, J.; Stambler, S.

    2004-11-01

    The MHD stability properties of a line-tied screw pinch have been studied without a nearby conducting shell in the rotating wall machine. Theory states the lineÂ-tied plasma will be unstable in the no-wall limit when qa < 1, and for a perfectly conducting wall qa < 1 - (a/b)^2, where a is the plasma radius and b is the wall radius. The region between these two values is where the resistive wall mode can be found. Initial experiments have been focused on finding the ideal stability limits with and without a wall present. The main diagnostic for measuring the MHD stability without a wall is a 2D array of 80 radial magnetic field sensors surrounding the plasma column. The experimental properties of the instability are a pronounced increase in the magnetic fluctuations when qa falls below one. qa is changed by controlling the plasma diameter, the external magnetic field, and the current in the plasma. The instability observed when using one gun can be stabilized when the central column is surrounded with plasma. The instability oscillates with a real frequency typical of an alfven wave propagation time along the axis of the machine. The 2D array indicate the unstable eigenfunction is line tied and predominantly n=1, m=1, consistent with predictions from theory. The adjacent poster discusses equilibrium measurements done on the plasma with a langmuir probe and b dot probe. This work was supported by the DoE.

  4. From viscosity and surface tension to marangoni flow in melts

    NASA Astrophysics Data System (ADS)

    Sun, Shouyi; Zhang, Ling; Jahanshahi, Sharif

    2003-10-01

    This article covers some of our recent work on slag viscosity, the surface tension of liquid Cu-O alloys, and the relative role of Marangoni and bulk flow on refractory wear in iron-silicate slags. A viscosity model developed for slags containing SiO2, Al2O3, Fe2O3, CaO, MgO, MnO, FeO, PbO, NiO, Cu2O, ZnO, CoO, and TiO2 is capable of representing the effects of temperature, silica, and network-modifier cations within a wide range of temperatures and compositions. It forms a useful part of a computational package for multiphase-equilibrium (MPE) calculations and for predicting slag viscosities. The models are well applicable to a range of industrial slags (blast furnace, new iron making, base-metal and Platinum Group Metals (PGM) smelting, and coal-ash slags). The package has also some capability of predicting the viscosity of slags containing suspended solids. The surface tension of liquid copper-oxygen alloys has also been analyzed. The adsorption behavior of oxygen in liquid copper is well represented by the combined Langmuir-Gibbs isotherm. According to the rate data for silica-rod dissolution in liquid iron-silicate slags at 1573 K, the preferential attack at the slag line diminishes as the linear velocity of flow at the surface of the rotating silica rod reaches 9 to 16 cm/s. A tentative analysis gives the critical condition, that relates the critical Reynolds (Re) and Marangoni (Ma) number by the equation Re*2=0.13 Ma*.

  5. The importance of EBIT data for Z-pinch plasma diagnostics

    SciTech Connect

    Safronova, A S; Kantsyrev, V L; Neill, P; Safronova, U I; Fedin, D A; Ouart, N D; Yilmaz, M F; Osborne, G; Shrestha, I; Williamson, K; Hoppe, T; Harris, C; Beiersdorfer, P; Hansen, S

    2007-04-04

    The results from the last six years of x-ray spectroscopy and spectropolarimetry of high energy density Z-pinch plasmas complemented by experiments with the electron beam ion trap (EBIT) at the Lawrence Livermore National Laboratory (LLNL) are presented. The two topics discussed are the development of M-shell x-ray W spectroscopic diagnostics and K-shell Ti spectropolarimetry of Z-pinch plasmas. The main focus is on radiation from a specific load configuration called an 'X-pinch'. X-pinches are excellent sources for testing new spectral diagnostics and for atomic modelling because of the high density and temperature of the pinch plasmas, which scale from a few {micro}m to several mm in size. They offer a variety of load configurations, which differ in wire connections, number of wires, and wire materials. In this work the study of X-pinches with tungsten wires combined with wires from other, lower-Z materials is reported. Utilizing data produced with the LLNL EBIT at different energies of the electron beam the theoretical prediction of line positions and intensity of M-shell W spectra were tested and calibrated. Polarization-sensitive X-pinch experiments at the University of Nevada, Reno (UNR) provide experimental evidence for the existence of strong electron beams in Ti and Mo X-pinch plasmas and motivate the development of x-ray spectropolarimetry of Z-pinch plasmas. This diagnostic is based on the measurement of spectra recorded simultaneously by two spectrometers with different sensitivity to the linear polarization of the observed lines and compared with theoretical models of polarization-dependent spectra. Polarization-dependent K-shell spectra from Ti X-pinches are presented and compared with model calculations and with spectra generated by a quasi-Maxwellian electron beam at the LLNL EBIT-II electron beam ion trap.

  6. Intense neutron pulse generation in dense Z-pinch

    NASA Astrophysics Data System (ADS)

    Bystritskii, V. M.; Glusko, Yu. A.; Mesyats, G. A.; Ratakhin, N. A.

    1989-12-01

    The problem of intense neutron pulse generation with fast dense Z-pinches (ZP) is analyzed for a modified approach. The analysis pertains to the interaction of a High Power Deuterium Beam (HPDB) with hot (Te≂1 keV) deuterium target formed by a ZP. The considerable decrease of the Coulomb ion-electron scattering cross-sections gives a corresponding increase of the deuterium range and neutron yield in the hot target. The generation of HPDB and ZP formation takes place at the same terawatt accelerator, by using in series with the ZP a plasma opening switch (POS), which is at the same time the Ion Plasma Filled Diode (IPFD). During the front of the current pulse the stable z-pinch implosion heats the ZP up to the keV temperature range with several kJ of energy input. Near the end of the current front the energy flow is being switched to HPDB generation due to the opening of the POS. The HPDB is focused ballistically at the axis of the ZP and transported along it in the azimutal magnetic field, producing a neutron burst. The analysis of ZP formation and heating, HPDB generation, its transport and neutron production is given.

  7. Ion Acceleration by Magnetic Pinch Instabilities- Powerful Neutron Sources

    NASA Astrophysics Data System (ADS)

    Hayes, Anna; Li, Hui

    2014-10-01

    Since the 1950s pinch discharges with deuterium gas have been known to produce large neutron bursts. During these early quests for laboratory fusion it was initially believed that the heat produced in the pinch led to sufficently high temperatures that these neutrons resulted from thermonuclear (TN) burn. However, a series of careful measurements led by Stirling Colgate was carried out to show that these neutrons did not result form TN burn. Rather, they resulted from an m = 0 sausage mode instability that accelerated the ions, causing beam-target interactions. Today, this same mechanism is used in dense plasma focus machines to generate intense neutron pulses for neutron activation experiments. One such experiment, to test the citicality of aging plutonium, is currently being planned at the Nevada Test Site. Helping to characterize the neutrons from the dense palsma focus to be used in this large experiment was the last applied physics project that Stirling work on. In this talk we will summarize the physics issues involved both in the original discovery in the 1950s and in today's experiments.

  8. Z-Pinch Driven Isentropic Compression for Inertial Fusion

    SciTech Connect

    Asay, J.R.; Hall, C.A.; Holland, K.G.; Slutz, S.A.; Spielman, R.B.; Stygar, W.A.

    1999-02-01

    The achievement of high gain with inertial fusion requires the compression of hydrogen isotopes to high density and temperatures. High densities can be achieved most efficiently by isentropic compression. This requires relatively slow pressure pulses on the order of 10-20 nanoseconds; however, the pressure profile must have the appropriate time. We present 1-D numerical simulations that indicate such a pressure profile can be generated by using pulsed power driven z pinches. Although high compression is calculated, the initial temperature is too low for ignition. Ignition could be achieved by heating a small portion of this compressed fuel with a short (-10 ps) high power laser pulse as previously described. Our 1-D calculations indicate that the existing Z-accelerator could provide the driving current (-20 MA) necessary to compress fuel to roughly 1500 times solid density. At this density the required laser energy is approximately 10 kJ. Multidimensional effects such as the Rayleigh-Taylor were not addressed in this brief numerical study. These effects will undoubtedly lower fuel compression for a given chive current. Therefore it is necessary to perform z-pinch driven compression experiments. Finally, we present preliminary experimental data from the Z-accelerator indicating that current can be efficiently delivered to appropriately small loads (- 5 mm radius) and that VISAR can be used measure high pressure during isentropic compression.

  9. Z-pinch modeling at Sandia National Laboratories

    SciTech Connect

    Hussey, T.W.; Matzen, M.K. ); Roderick, N.F. )

    1989-12-01

    The recent emphasis of the Sandia National Laboratories fast Z-pinch effort has been to utilize an imploding gas puff to produce the pump radiation for a photoionization-pumped soft x-ray laser. Because of their potential for utilizing the cylindrical convergence of a fast Z-pinch, we use hollow, coaxial, cylindrical targets to stagnate the implosion. The kilovolt component of radiation produced by this stagnation is the photoionizing pump source for the lasant material that is inside the cylinder. Such a system requires a detailed understanding of the dynamics of both the target and the imploding gas puff as well as their radiative properties. In recent years at Sandia we have studied a number of aspects of this process theoretically, which we describe here. We have considered large scale length non-uniformities resulting from flaring of the gas puff that lead to nonuniform target closure, and shorter wavelength nonuniformities resulting from the hydromagnetic Rayleigh-Taylor instability. More recently, we have emphasized the profound effect of radiation collapse'' of the imploding annular plasma before it reaches the target. This process, which varies considerably with gas puff material and mass (and, therefore, implosion energy), alters density gradient and radiation preheat during the run-in, greatly affecting target dynamics. In addition, we have developed detailed designs for these central targets, which are found to levy severe requirements on gas-puff implosion performance. The feasibility of meeting these requirements, which may be ameliorated by increased driver energy, is discussed.

  10. D-D fusion experiments using fast Z pinches

    SciTech Connect

    Spielman, R.B.; Baldwin, G.T.; Cooper, G.

    1998-03-01

    The development of high current (I > 10 MA) drivers provides the authors with a new tool for the study of neutron-producing plasmas in the thermal regime. The imploded deuterium mass (or collisionality) increases as I{sup 2} and the ability of the driver to heat the plasma to relevant fusion temperatures improves as the power of the driver increases. Additionally, fast (<100 ns) implosions are more stable to the usual MHD instabilities that plagued the traditional slower implosions. The authors describe experiments in which deuterium gas puffs or CD{sub 2} fiber arrays were imploded in a fast z-pinch configuration on Sandia`s Saturn facility generating up to 3 {times} 10{sup 12} D-D neutrons. These experiments were designed to explore the physics of neutron-generating plasmas in a z-pinch geometry. Specifically, the authors intended to produce neutrons from a nearly thermal plasma where the electrons and ions have a nearly Maxwellian distribution. This is to be clearly differentiated from the more usual D-D beam-target neutrons generated in many dense plasma focus (DPF) devices.

  11. Simulation of Wire-Array Z Pinches with ALEGRA

    NASA Astrophysics Data System (ADS)

    Chantrenne, Sophie; Bliss, David; Cochrane, Kyle; Coverdale, Christine; Deeney, Chris; Hall, Clint; Haill, Thomas; Jones, Brent; Lepell, Paul; Oliver, Bryan; Sinars, Daniel

    2006-10-01

    Wire-array z pinches provide the x-ray radiation drive for Inertial Confinement Fusion Experiments at Sandia National Laboratories. A physical understanding of the physics of wire-array z pinches is important in providing a future radiation source capable of driving high-yield fusion capsules. Modeling of wire-array implosions on the Z machine were performed using the 2-D radiation MHD code Alegra. These new calculations use more accurate initial conditions that are more representative of the experimental data, allowing us to model the implosion through stagnation, to avoid radiation collapse, and to generate a radiation pulse that compares well with data. Code predictions will be compared with tungsten & aluminum wire-array data from Z. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the U.S. Department of Energy under Contract No. DE-AC04- 94AL85000. a Ktech Corporation, 1300 Eubank Blvd. S.E., Albuquerque, NM 87123-3336

  12. Study of gas-puff Z-pinches on COBRA

    SciTech Connect

    Qi, N.; Rosenberg, E. W.; Gourdain, P. A.; Grouchy, P. W. L. de; Kusse, B. R.; Hammer, D. A.; Bell, K. S.; Shelkovenko, T. A.; Potter, W. M.; Atoyan, L.; Cahill, A. D.; Evans, M.; Greenly, J. B.; Hoyt, C. L.; Pikuz, S. A.; Schrafel, P. C.; Kroupp, E.; Fisher, A.; Maron, Y.

    2014-11-15

    Gas-puff Z-pinch experiments were conducted on the 1 MA, 200 ns pulse duration Cornell Beam Research Accelerator (COBRA) pulsed power generator in order to achieve an understanding of the dynamics and instability development in the imploding and stagnating plasma. The triple-nozzle gas-puff valve, pre-ionizer, and load hardware are described. Specific diagnostics for the gas-puff experiments, including a Planar Laser Induced Fluorescence system for measuring the radial neutral density profiles along with a Laser Shearing Interferometer and Laser Wavefront Analyzer for electron density measurements, are also described. The results of a series of experiments using two annular argon (Ar) and/or neon (Ne) gas shells (puff-on-puff) with or without an on- (or near-) axis wire are presented. For all of these experiments, plenum pressures were adjusted to hold the radial mass density profile as similar as possible. Initial implosion stability studies were performed using various combinations of the heavier (Ar) and lighter (Ne) gasses. Implosions with Ne in the outer shell and Ar in the inner were more stable than the opposite arrangement. Current waveforms can be adjusted on COBRA and it was found that the particular shape of the 200 ns current pulse affected on the duration and diameter of the stagnated pinched column and the x-ray yield.

  13. Reducing blood viscosity with magnetic fields

    NASA Astrophysics Data System (ADS)

    Tao, R.; Huang, K.

    2011-07-01

    Blood viscosity is a major factor in heart disease. When blood viscosity increases, it damages blood vessels and increases the risk of heart attacks. Currently, the only method of treatment is to take drugs such as aspirin, which has, however, several unwanted side effects. Here we report our finding that blood viscosity can be reduced with magnetic fields of 1 T or above in the blood flow direction. One magnetic field pulse of 1.3 T lasting ˜1 min can reduce the blood viscosity by 20%-30%. After the exposure, in the absence of magnetic field, the blood viscosity slowly moves up, but takes a couple of hours to return to the original value. The process is repeatable. Reapplying the magnetic field reduces the blood viscosity again. By selecting the magnetic field strength and duration, we can keep the blood viscosity within the normal range. In addition, such viscosity reduction does not affect the red blood cells’ normal function. This technology has much potential for physical therapy.

  14. Reducing blood viscosity with magnetic fields.

    PubMed

    Tao, R; Huang, K

    2011-07-01

    Blood viscosity is a major factor in heart disease. When blood viscosity increases, it damages blood vessels and increases the risk of heart attacks. Currently, the only method of treatment is to take drugs such as aspirin, which has, however, several unwanted side effects. Here we report our finding that blood viscosity can be reduced with magnetic fields of 1 T or above in the blood flow direction. One magnetic field pulse of 1.3 T lasting ~1 min can reduce the blood viscosity by 20%-30%. After the exposure, in the absence of magnetic field, the blood viscosity slowly moves up, but takes a couple of hours to return to the original value. The process is repeatable. Reapplying the magnetic field reduces the blood viscosity again. By selecting the magnetic field strength and duration, we can keep the blood viscosity within the normal range. In addition, such viscosity reduction does not affect the red blood cells' normal function. This technology has much potential for physical therapy.

  15. THE VISCOSITY OF HELIUM-CESIUM MIXTURES,

    DTIC Science & Technology

    The viscosities of helium-cesium mixtures having mole fractions of cesium from zero to unity were evaluated using a Lennard - Jones 6-12 interaction potential for all encounters in the Enskog Chapman expressions for the viscosity of a binary mixture. (Author)

  16. Viscosity test standards for engine oils

    SciTech Connect

    Not Available

    1990-01-01

    This report presents a compilation of 10 ASTM standards that cover both low and high temperature viscosity tests for automotive engine oils, with respect to low temperature flow properties and performance requirements under high temperature, high shear rate conditions. Society of Automotive Engineer's Engine Oil Viscosity Classification SAE J300 is included to provide low temperature high shear rate method.

  17. Surface dilatational viscosity of Langmuir monolayers

    NASA Astrophysics Data System (ADS)

    Lopez, Juan; Vogel, Michael; Hirsa, Amir

    2003-11-01

    With increased interest in microfluidic systems, interfacial phenomena is receiving more attention. As the length scales of fluid problems decrease, the surface to volume ratio increases and the coupling between interfacial flow and bulk flow becomes increasingly dominated by effects due to intrinsic surface viscosities (shear and dilatational), in comparison to elastic effects (due to surface tension gradients). The surface shear viscosity is well-characterized, as cm-scale laboratory experiments are able to isolate its effects from other interfacial processes (e.g., in the deep-channel viscometer). The same is not true for the dilatational viscosity, because it acts in the direction of surface tension gradients. Their relative strength scale with the capillary number, and for cm-scale laboratory flows, surface tension effects tend to dominate. In microfluidic scale flows, the scaling favors viscosity. We have devised an experimental apparatus which is capable of isolating and enhancing the effects of dilatational viscosity at the cm scales by driving the interface harmonically in time, while keeping the interface flat. In this talk, we shall present both the theory for how this works as well as experimental measurements of surface velocity from which we deduce the dilatational viscosity of several monolayers on the air-water interface over a substantial range of surface concentrations. Anomalous behavior over some range of concentration, which superficially indicates negative viscosity, maybe explained in terms of compositional effects due to large spatial and temporal variations in concentration and corresponding viscosity.

  18. Rotating Wavepackets

    ERIC Educational Resources Information Center

    Lekner, John

    2008-01-01

    Any free-particle wavepacket solution of Schrodinger's equation can be converted by differentiations to wavepackets rotating about the original direction of motion. The angular momentum component along the motion associated with this rotation is an integral multiple of [h-bar]. It is an "intrinsic" angular momentum: independent of origin and…

  19. Rotating Wavepackets

    ERIC Educational Resources Information Center

    Lekner, John

    2008-01-01

    Any free-particle wavepacket solution of Schrodinger's equation can be converted by differentiations to wavepackets rotating about the original direction of motion. The angular momentum component along the motion associated with this rotation is an integral multiple of [h-bar]. It is an "intrinsic" angular momentum: independent of origin and…

  20. Computation of turbulent rotating channel flow with an algebraic Reynolds stress model

    NASA Technical Reports Server (NTRS)

    Warfield, M. J.; Lakshminarayana, B.

    1986-01-01

    An Algebraic Reynolds Stress Model has been implemented to modify the Kolmogorov-Prandtl eddy viscosity relation to produce an anisotropic turbulence model. The eddy viscosity relation becomes a function of the local turbulent production to dissipation ratio and local turbulence/rotation parameters. The model is used to predict fully-developed rotating channel flow over a diverse range of rotation numbers. In addition, predictions are obtained for a developing channel flow with high rotation. The predictions are compared with the experimental data available. Good predictions are achieved for mean velocity and wall shear stress over most of the rotation speeds tested. There is some prediction breakdown at high rotation (rotation number greater than .10) where the effects of the rotation on turbulence become quite complex. At high rotation and low Reynolds number, the laminarization on the trailing side represents a complex effect of rotation which is difficult to predict with the described models.

  1. Plasma viscosity elevations with simulated weightlessness

    NASA Technical Reports Server (NTRS)

    Martin, D. G.; Convertino, V. A.; Goldwater, D.; Ferguson, E. W.; Schoomaker, E. B.

    1986-01-01

    A hypothesis correlating an increase in blood viscosity during bed rest to a decrease in aerobic capacity during simulated weightlessness is tested. Eight human subjects were studied on the sixth day of bed rest during two consecutive 10-d bed rest periods separated by a 14-d recovery interval designed to simulate the flight-layover schedule of Shuttle astronauts. Plasma viscosity and volume were measured, together with maximal aerobic capacity (VO2max). An increase in hematocrit, plasma protein, and fibrinogen concentrations was found, contributing to an elevation in plasma viscosity. VO2max decreased significantly in the first, but not the second bed rest cycle, and though many individuals exhibited a decrease in plasma volume and aerobic capacity coupled with elevated plasma viscosity, correlations between these variables were lacking. It is concluded that the decrease in VO2max observed following simulated weightlessness cannot be attributed to alterations in muscle blood flow resulting from increased blood viscosity.

  2. Plasma viscosity elevations with simulated weightlessness

    NASA Technical Reports Server (NTRS)

    Martin, D. G.; Convertino, V. A.; Goldwater, D.; Ferguson, E. W.; Schoomaker, E. B.

    1986-01-01

    A hypothesis correlating an increase in blood viscosity during bed rest to a decrease in aerobic capacity during simulated weightlessness is tested. Eight human subjects were studied on the sixth day of bed rest during two consecutive 10-d bed rest periods separated by a 14-d recovery interval designed to simulate the flight-layover schedule of Shuttle astronauts. Plasma viscosity and volume were measured, together with maximal aerobic capacity (VO2max). An increase in hematocrit, plasma protein, and fibrinogen concentrations was found, contributing to an elevation in plasma viscosity. VO2max decreased significantly in the first, but not the second bed rest cycle, and though many individuals exhibited a decrease in plasma volume and aerobic capacity coupled with elevated plasma viscosity, correlations between these variables were lacking. It is concluded that the decrease in VO2max observed following simulated weightlessness cannot be attributed to alterations in muscle blood flow resulting from increased blood viscosity.

  3. Anomalous magnetic viscosity in relativistic accretion disks

    NASA Astrophysics Data System (ADS)

    Lin, Fujun; Liu, Sanqiu; Li, Xiaoqing

    2013-07-01

    It has been proved that the self-generated magnetic fields by transverse plasmons in the relativistic regime are modulationally unstable, leading to a self-similar collapse of the magnetic flux tubes and resulting in local magnetic structures; highly spatially intermittent flux is responsible for generating the anomalous viscosity. We derive the anomalous magnetic viscosity coefficient, in accretion disks around compact objects, such as black holes, pulsars and quasars, where the plasmas are relativistic, in order to help clarify the nature of viscosity in the theory of accretion disks. The results indicate that, the magnetic viscosity is modified by the relativistic effects of plasmas, and its' strength would be 1015 stronger than the molecular viscosity, which may be helpful in explaining the observations.

  4. Rotational elasticity

    NASA Astrophysics Data System (ADS)

    Vassiliev, Dmitri

    2017-04-01

    We consider an infinite three-dimensional elastic continuum whose material points experience no displacements, only rotations. This framework is a special case of the Cosserat theory of elasticity. Rotations of material points are described mathematically by attaching to each geometric point an orthonormal basis that gives a field of orthonormal bases called the coframe. As the dynamical variables (unknowns) of our theory, we choose the coframe and a density. We write down the general dynamic variational functional for our rotational theory of elasticity, assuming our material to be physically linear but the kinematic model geometrically nonlinear. Allowing geometric nonlinearity is natural when dealing with rotations because rotations in dimension three are inherently nonlinear (rotations about different axes do not commute) and because there is no reason to exclude from our study large rotations such as full turns. The main result of the talk is an explicit construction of a class of time-dependent solutions that we call plane wave solutions; these are travelling waves of rotations. The existence of such explicit closed-form solutions is a non-trivial fact given that our system of Euler-Lagrange equations is highly nonlinear. We also consider a special case of our rotational theory of elasticity which in the stationary setting (harmonic time dependence and arbitrary dependence on spatial coordinates) turns out to be equivalent to a pair of massless Dirac equations. The talk is based on the paper [1]. [1] C.G.Boehmer, R.J.Downes and D.Vassiliev, Rotational elasticity, Quarterly Journal of Mechanics and Applied Mathematics, 2011, vol. 64, p. 415-439. The paper is a heavily revised version of preprint https://arxiv.org/abs/1008.3833

  5. Resistive wall instabilities and tearing mode dynamics in the EXTRAP T2R thin shell reversed-field pinch

    NASA Astrophysics Data System (ADS)

    Malmberg, J.-A.; Brunsell, P. R.

    2002-01-01

    Observations of resistive wall instabilities and tearing mode dynamics in the EXTRAP T2R thin shell (τw=6 ms) reversed field pinch are described. A nonresonant mode (m=1,n=-10) with the same handedness as the internal field grows nearly exponentially with an average growth time of about 2.6 ms (less than 1/2 of the shell time) consistent with linear stability theory. The externally nonresonant unstable modes (m=1,n>0), predicted by linear stability theory, are observed to have only low amplitudes (in the normal low-Θ operation mode of the device). The radial field of the dominant internally resonant tearing modes (m=1,n=-15 to n=-12) remain low due to spontaneous fast mode rotation, corresponding to angular phase velocities up to 280 krad/s. Phase aligned mode structures are observed to rotate toroidally with an average angular velocity of 40 krad/s, in the opposite direction of the plasma current. Toward the end of the discharge, the radial field of the internally resonant modes grows as the modes slow down and become wall-locked, in agreement with nonlinear computations. Fast rotation of the internally resonant modes has been observed only recently and is attributed to a change of the front-end system (vacuum vessel, shell, and TF coil) of the device.

  6. Eruptive viscosity and volcano morphology

    NASA Technical Reports Server (NTRS)

    Posin, Seth B.; Greeley, Ronald

    1988-01-01

    Terrestrial central volcanoes formed predominantly from lava flows were classified as shields, stratovolcanoes, and domes. Shield volcanoes tend to be large in areal extent, have convex slopes, and are characterized by their resemblance to inverted hellenic war shields. Stratovolcanoes have concave slopes, whereas domes are smaller and have gentle convex slopes near the vent that increase near the perimeter. In addition to these differences in morphology, several other variations were observed. The most important is composition: shield volcanoes tend to be basaltic, stratovolcanoes tend to be andesitic, and domes tend to be dacitic. However, important exceptions include Fuji, Pico, Mayon, Izalco, and Fuego which have stratovolcano morphologies but are composed of basaltic lavas. Similarly, Ribkwo is a Kenyan shield volcano composed of trachyte and Suswa and Kilombe are shields composed of phonolite. These exceptions indicate that eruptive conditions, rather than composition, may be the primary factors that determine volcano morphology. The objective of this study is to determine the relationships, if any, between eruptive conditions (viscosity, erupted volume, and effusion rate) and effusive volcano morphology. Moreover, it is the goal of this study to incorporate these relationships into a model to predict the eruptive conditions of extraterrestrial (Martian) volcanoes based on their morphology.

  7. Both protein adsorption and aggregation contribute to shear yielding and viscosity increase in protein solutions.

    PubMed

    Castellanos, Maria Monica; Pathak, Jai A; Colby, Ralph H

    2014-01-07

    A combination of sensitive rotational rheometry and surface rheometry with a double-wall ring were used to identify the origins of the viscosity increase at low shear rates in protein solutions. The rheology of two high molecular weight proteins is discussed: Bovine Serum Albumin (BSA) in a Phosphate Buffered Saline solution and an IgG1 monoclonal antibody (mAb) in a formulation buffer containing small quantities of a non-ionic surfactant. For surfactant-free BSA solutions, the interfacial viscosity dominates the low shear viscosity measured in rotational rheometers, while the surfactant-laden mAb solution has an interfacial viscosity that is small compared to that from aggregation in the bulk. A viscoelastic film forms at the air/water interface in the absence of surfactant, contributing to an apparent yield stress (thus a low shear viscosity increase) in conventional bulk rheology measurements. Addition of surfactant eliminates the interfacial yield stress. Evidence of a bulk yield stress arising from protein aggregation is presented, and correlated with results from standard characterization techniques used in the bio-pharmaceutical industry. The protein film at the air/water interface and bulk aggregates both lead to an apparent viscosity increase and their contributions are quantified using a dimensionless ratio of the interfacial and total yield stress. While steady shear viscosities at shear rates below ∼1 s(-1) contain rich information about the stability of protein solutions, embodied in the measured yield stress, such low shear rate data are regrettably often not measured and reported in the literature.

  8. Soft x-ray tomography system for the toroidal pinch experiment-RX reversed-field pinch

    SciTech Connect

    Koguchi, H.; Shimada, T.; Asai, T.; Yagi, Y.; Hirano, Y.; Sakakita, H.

    2004-10-01

    A soft x-ray (SXR) measurement system for tomography analysis on a reversed-field pinch machine. torodial pinch experiment, RX [TPE-RX, R/a=1.72/0.45 m, I{sub p}<1 MA (designed)], is presented. The soft x-ray imaging system consists of two surface barrier detector (SBD) arrays that are vertical and horizontal. Thirteen SBDs are installed on the vertical ports and used for the measurement along vertical lines of sight. Eleven SBDs are installed on the horizontal port and used for the measurement along a fan-shaped line of sight. These detectors have 15-{mu}m-thick Be foil with sensitivity in the soft x-ray range. This system is installed in order to study the structure of the SXR emission from the plasma core and to know the relation between global performance and magnetohydrodynamics dynamics. This system has been used under several operating conditions in addition to those of standard operation. The first results of these experiments are reported.

  9. The experimental localization of Aubry-Mather sets using regularization techniques inspired by viscosity theory.

    PubMed

    Guzzo, Massimiliano; Bernardi, Olga; Cardin, Franco

    2007-09-01

    We provide a new method for the localization of Aubry-Mather sets in quasi-integrable two-dimensional twist maps. Inspired by viscosity theories, we introduce regularization techniques based on the new concept of "relative viscosity and friction," which allows one to obtain regularized parametrizations of invariant sets with irrational rotation number. Such regularized parametrizations allow one to compute a curve in the phase-space that passes near the Aubry-Mather set, and an invariant measure whose density allows one to locate the gaps on the curve. We show applications to the "golden" cantorus of the standard map as well as to a more general case.

  10. Computation of shear viscosity of colloidal suspensions by SRD-MD.

    PubMed

    Laganapan, A M K; Videcoq, A; Bienia, M; Ala-Nissila, T; Bochicchio, D; Ferrando, R

    2015-04-14

    The behaviour of sheared colloidal suspensions with full hydrodynamic interactions (HIs) is numerically studied. To this end, we use the hybrid stochastic rotation dynamics-molecular dynamics (SRD-MD) method. The shear viscosity of colloidal suspensions is computed for different volume fractions, both for dilute and concentrated cases. We verify that HIs help in the collisions and the streaming of colloidal particles, thereby increasing the overall shear viscosity of the suspension. Our results show a good agreement with known experimental, theoretical, and numerical studies. This work demonstrates the ability of SRD-MD to successfully simulate transport coefficients that require correct modelling of HIs.

  11. A three-dimensional model for the effective viscosity of bacterial suspensions.

    SciTech Connect

    Haines, B. M.; Sokolov, A.; Aranson, I. S.; Berlyand, L.; Karpeev, D. A.; Pennsylvania State Univ.; Illinois Inst. of Tech.

    2009-01-01

    We derive the effective viscosity of dilute suspensions of swimming bacteria from the microscopic details of the interaction of an elongated body with the background flow. An individual bacterium propels itself forward by rotating its flagella and reorients itself randomly by tumbling. Due to the bacterium's asymmetric shape, interactions with a prescribed generic (such as planar shear or straining) background flow cause the bacteria to preferentially align in directions in which self-propulsion produces a significant reduction in the effective viscosity, in agreement with recent experiments on suspensions of Bacillus subtilis.

  12. Computation of shear viscosity of colloidal suspensions by SRD-MD

    SciTech Connect

    Laganapan, A. M. K.; Videcoq, A. Bienia, M.; Ala-Nissila, T.; Bochicchio, D.; Ferrando, R.

    2015-04-14

    The behaviour of sheared colloidal suspensions with full hydrodynamic interactions (HIs) is numerically studied. To this end, we use the hybrid stochastic rotation dynamics-molecular dynamics (SRD-MD) method. The shear viscosity of colloidal suspensions is computed for different volume fractions, both for dilute and concentrated cases. We verify that HIs help in the collisions and the streaming of colloidal particles, thereby increasing the overall shear viscosity of the suspension. Our results show a good agreement with known experimental, theoretical, and numerical studies. This work demonstrates the ability of SRD-MD to successfully simulate transport coefficients that require correct modelling of HIs.

  13. Thermal conductivity and viscosity measurements of ethylene glycol-based Al2O3 nanofluids

    PubMed Central

    2011-01-01

    The dispersion and stability of nanofluids obtained by dispersing Al2O3 nanoparticles in ethylene glycol have been analyzed at several concentrations up to 25% in mass fraction. The thermal conductivity and viscosity were experimentally determined at temperatures ranging from 283.15 K to 323.15 K using an apparatus based on the hot-wire method and a rotational viscometer, respectively. It has been found that both thermal conductivity and viscosity increase with the concentration of nanoparticles, whereas when the temperature increases the viscosity diminishes and the thermal conductivity rises. Measured enhancements on thermal conductivity (up to 19%) compare well with literature values when available. New viscosity experimental data yield values more than twice larger than the base fluid. The influence of particle size on viscosity has been also studied, finding large differences that must be taken into account for any practical application. These experimental results were compared with some theoretical models, as those of Maxwell-Hamilton and Crosser for thermal conductivity and Krieger and Dougherty for viscosity. PMID:21711737

  14. Thermal conductivity and viscosity measurements of ethylene glycol-based Al2O3 nanofluids

    NASA Astrophysics Data System (ADS)

    Pastoriza-Gallego, María José; Lugo, Luis; Legido, José Luis; Piñeiro, Manuel M.

    2011-12-01

    The dispersion and stability of nanofluids obtained by dispersing Al2O3 nanoparticles in ethylene glycol have been analyzed at several concentrations up to 25% in mass fraction. The thermal conductivity and viscosity were experimentally determined at temperatures ranging from 283.15 K to 323.15 K using an apparatus based on the hot-wire method and a rotational viscometer, respectively. It has been found that both thermal conductivity and viscosity increase with the concentration of nanoparticles, whereas when the temperature increases the viscosity diminishes and the thermal conductivity rises. Measured enhancements on thermal conductivity (up to 19%) compare well with literature values when available. New viscosity experimental data yield values more than twice larger than the base fluid. The influence of particle size on viscosity has been also studied, finding large differences that must be taken into account for any practical application. These experimental results were compared with some theoretical models, as those of Maxwell-Hamilton and Crosser for thermal conductivity and Krieger and Dougherty for viscosity.

  15. A crucial role for Ras suppressor-1 (RSU-1) revealed when PINCH and ILK binding is disrupted.

    PubMed

    Elias, Maria C; Pronovost, Stephen M; Cahill, Kinley J; Beckerle, Mary C; Kadrmas, Julie L

    2012-07-01

    PINCH, integrin-linked kinase (ILK) and Ras suppressor-1 (RSU-1) are molecular scaffolding proteins that form a physical complex downstream of integrins, and have overlapping roles in cellular adhesion. In Drosophila, PINCH and ILK colocalize in cells and have indistinguishable functions in maintaining wing adhesion and integrin to actin linkage in the muscle. We sought to determine whether the direct physical interaction between PINCH and ILK was essential for their functions using transgenic flies expressing a version of PINCH with a point mutation that disrupts ILK binding (PINCH(Q38A)). We demonstrate that the PINCH-ILK interaction is not required for viability, for integrin-mediated adhesion of the wing or muscle, or for maintaining appropriate localization or levels of either PINCH or ILK. These results suggest alternative modes for PINCH localization, stabilization and linkage to the actin cytoskeleton that are independent of a direct interaction with ILK. Furthermore, we identified a synthetic lethality in flies carrying both the PINCH(Q38A) mutation and a null mutation in the gene encoding RSU-1. This lethality does not result from PINCH mislocalization or destabilization, and illustrates a novel compensatory role for RSU-1 in maintaining viability in flies with compromised PINCH-ILK binding. Taken together, this work highlights the existence of redundant mechanisms in adhesion complex assembly that support integrin function in vivo.

  16. Pulse Power Compression by Cutting a Dense Z-Pinch with a Laser Beam

    NASA Astrophysics Data System (ADS)

    Winterberg, F.

    1999-07-01

    A thin cut made through a z-pinch by an intense laser beam can become a magnetically insulated diode crossed by an intense ion beam. For larger cuts, the gap is crossed by an intense relativistic electron beam, stopped by magnetic bremsstrahlung resulting in a pointlike intense x-ray source. In either case, the impedance of the pinch discharge is increased, with the power delivered rising in the same pro-portion. A magnetically insulated cut is advantageous for three reasons: First, with the ion current com-parable to the Alfvèn ion current, the pinch instabilities are reduced. Second, with the energy deposit-ed into fast ions, a non-Maxwellian velocity distribution is established increasing<σ ν> value for nuclear fusion reactions taking place in the pinch discharge. Third, in a high density z-pinch plasma, the intense ion beam can launch a thermonuclear detonation wave propagating along the pinch discharge channel. For larger cuts the soft x-rays produced by magnetic bremsstrahlung can be used to drive a thermonuclear hohlraum target. Finally, the proposed pulse power compression scheme permits to use a cheap low power d.c. source charging a magnetic storage coil delivering the magnetically stored energy to the pinch discharge load by an exploding wire opening switch.

  17. A Reactor Development Scenario for the FUZE Shear-flow Stabilized Z-pinch

    NASA Astrophysics Data System (ADS)

    McLean, H. S.; Higginson, D. P.; Schmidt, A.; Tummel, K. K.; Shumlak, U.; Nelson, B. A.; Claveau, E. L.; Golingo, R. P.; Weber, T. R.

    2016-10-01

    We present a conceptual design, scaling calculations, and a development path for a pulsed fusion reactor based on the shear-flow-stabilized Z-pinch device. Experiments performed on the ZaP device have demonstrated stable operation for 40 us at 150 kA total discharge current (with 100 kA in the pinch) for pinches that are 1cm in diameter and 100 cm long. Scaling calculations show that achieving stabilization for a pulse of 100 usec, for discharge current 1.5 MA, in a shortened pinch 50 cm, results in a pinch diameter of 200 um and a reactor plant Q 5 for reasonable assumptions of the various system efficiencies. We propose several key intermediate performance levels in order to justify further development. These include achieving operation at pinch currents of 300 kA, where Te and Ti are calculated to exceed 1 keV, 700 kA where fusion power exceeds pinch input power, and 1 MA where fusion energy per pulse exceeds input energy per pulse. This work funded by USDOE ARPAe ALPHA Program and performed under the auspices of Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-697801.

  18. Lower eyelid position after transconjunctival lower blepharoplasty with versus without a skin pinch.

    PubMed

    Taban, Mehryar; Taban, Mehran; Perry, Julian D

    2008-01-01

    To evaluate the effect of transconjunctival lower blepharoplasty with or without a skin pinch on lower eyelid position. Retrospective analysis of patients undergoing bilateral lower blepharoplasty using a transconjunctival approach with or without a skin pinch. Patients undergoing other surgical procedures that could affect lower eyelid position were excluded. Twenty-five patients (50 eyes) underwent transconjunctival blepharoplasty without skin pinch and 20 patients (40 eyes) underwent transconjunctival blepharoplasty with a skin-pinch technique. Preoperative and postoperative photographs were measured for the horizontal corneal diameter and distance from light reflex to lower eyelid margin (MRD2). The ratio of MRD2 to corneal diameter was multiplied by 11 to standardize to a corneal diameter of 11 mm. Student t test was used for statistical analysis. There were 8 male and 37 female patients. Average follow-up was 4 months. Mean preoperative standardized MRD2 was 4.68 mm and 4.65 mm for transconjunctival blepharoplasty without and with skin pinch, respectively. Mean postoperative standardized MRD2 was 4.73 mm and 4.70 mm for transconjunctival blepharoplasty without and with skin pinch, respectively. The mean change in lower eyelid position was 0.05 mm after each technique. The change in lower eyelid position was not statistically significant for either group (p > 0.5). There was no significant difference in lower eyelid position change between the 2 groups (p > 0.99). Transconjunctival lower blepharoplasty with or without a skin pinch yields a stable postoperative lower eyelid position.

  19. Neuronal PINCH is Regulated by TNF-α and is Required for Neurite Extension

    PubMed Central

    Jatiani, Asavari; Pannizzo, Paola; Gualco, Elisa; Del-Valle, Luis

    2011-01-01

    During HIV infection of the CNS, neurons are damaged by viral proteins, such as Tat and gp120, or by inflammatory factors, such as TNF-α, that are released from infected and/or activated glial cells. Host responses to this damage may include the induction of survival or repair mechanisms. In this context, previous studies report robust expression of a protein called particularly interesting new cysteine histidine-rich protein (PINCH), in the neurons of HIV patients’ brains, compared with nearly undetectable levels in HIV-negative individuals (Rearden et al., J Neurosci Res 86:2535–2542, 2008), suggesting PINCH’s involvement in neuronal signaling during HIV infection of the brain. To address potential triggers for PINCH induction in HIV patients’ brains, an in vitro system mimicking some aspects of HIV infection of the CNS was utilized. We investigated neuronal PINCH expression, subcellular distribution, and biological consequences of PINCH sequestration upon challenge with Tat, gp120, and TNF-α. Our results indicate that in neurons, TNF-α stimulation increases PINCH expression and changes its subcellular localization. Furthermore, PINCH mobility is required to maintain neurite extension upon challenge with TNF-α. PINCH may function as a neuron-specific host-mediated response to challenge by HIV-related factors in the CNS. PMID:20689998

  20. The analytical model for vortex ring pinch-off process based on the energy extremum principle

    NASA Astrophysics Data System (ADS)

    Xiang, Yang; Liu, Hong; Qin, Suyang; Wang, Fuxin

    2015-11-01

    The discovery of vortex ring pinch-off is greatly helpful for us to understand the mechanism of optimal vortex formation, which further implies the optimal biological propulsion for animals. The vortex ring pinch-off implies its limiting formation and is dominated by the energy extremum principle. However, it is found that vortex ring pinch-off is a continuous process rather than a transient timescale. Therefore, we are wondering that how to identify the onset and end of pinch-off process. Based on the Kelvin-Benjamin variational principle, a dimensionless energy number is adopted to characterize the energy evolution of vortex rings. The vortex ring flow fields are obtained by DPIV with the piston-cylinder setup, and their geometric structures are identified using its Lagrangian coherent structures. The results show that the dimensionless energy numbers with the steady translating vortex rings share a critical value. It is then demonstrated that the dimensionless energy number dominates the onset and the end of pinch-off process. Besides, the onset and end of pinch-off can also be identified using LCSs. Additionally, based on the dimensionless energy number or LCSs, the corresponding vortex ring formation times(L/D) for the onset or the end of pinch-off are consistent.

  1. 100 ns Z-Pinch Performance on the Inductive-Energy-Based ACE 4 Generator

    NASA Astrophysics Data System (ADS)

    Coleman, Philip; Thompson, John; Crumley, Randy; Failor, Bruce; Goodrich, Phillip; Parks, Don; Rauch, John; Song, Yuanxu; Steen, Paul; Waisman, Eduardo; Weber, Bruce; Moosman, Bryan; Qi, Niansheng; Schein, Jochen; McFarland, Mike; Campbell, Kelly; Krishnan, Mahadevan

    2000-10-01

    We report on the performance of a short implosion time ( ~100 ns) argon z-pinch using an inductive-energy-storage system. The generator, ACE 4, used a plasma opening switch (POS) to conduct for over a microsecond before driving the short implosion time 2.5 cm diameter Double Eagle gas nozzle. (Previously reported ACE 4 results used longer implosion times, 150 to over 300 ns, with z-pinch load diameters up to 14 cm.) The Double Eagle nozzle, which produces more than 20 kJ of argon K-shell radiation with a current I of almost 4 MA on Double Eagle, produced more than 6 kJ with 3 MA on ACE 4. This performance is consistent with the expected I to the 4th scaling. Pinch behavior on the two machines was quite similar in terms of zippering, pulse width and pinch diameter. As on Double Eagle, the gas flow away from the nozzle was observed to pinch best. On ACE 4, recessing the nozzle behind a wire grid cathode plane moved the high output part of the pinch down to the cathode plane. This allowed us to reduce the pinch length and load inductance, hence increasing load current and yield. Similar changes could be exploited on other gas puff loads and generators to enhance x-ray output. (Thompson, et. al., report elsewhere at this meeting on the performance of the POS and its interaction with the PRS.)

  2. Simulation of high-energy proton production by fast magnetosonic shock waves in pinched plasma discharges

    NASA Astrophysics Data System (ADS)

    Mizuguchi, Yusuke; Sakai, Jun-Ichi; Yousefi, Hamid Reza; Haruki, Takayuki; Masugata, Katsumi

    2007-03-01

    High-energy particles of a few hundred keV for electrons and up to MeV for ions were observed in a plasma focus device. Haruki et al. [Phys. Plasmas 13, 082106-1 (2006)] studied the mechanism of high-energy particle production in pinched plasma discharges by use of a 3D relativistic and fully electromagnetic particle-in-cell code. It was found that the pinched current is unstable against a sausage instability, and then becomes unstable against a kink instability. As a result high-energy electrons were observed, but protons with MeV energies were not observed. In this paper the same pinch dynamics as Haruki and co-workers is investigated, focusing on the shock formation and the shock acceleration during the pinched current. It is found that a fast magnetosonic shock wave is produced during the pinching phase which, after the maximum pinch occurs, is strongly enhanced and propagates outwards. Some protons trapped in the electrostatic potential produced near the shock front can be accelerated to a few MeV by the surfatron acceleration mechanism. It is also found that the protons accelerated along the pinched axis have a ring-shaped angular distribution that is observed from numerous experiments.

  3. Supergranulation rotation

    NASA Astrophysics Data System (ADS)

    Schou, Jesper; Beck, John G.

    2001-01-01

    Simple convection models estimate the depth of supergranulation at approximately 15,000 km which suggests that supergranules should rotate at the rate of the plasma in the outer 2% of the Sun by radius. Previous measurements (Snodgrass & Ulrich, 1990; Beck & Schou, 2000) found that supergranules rotate significantly faster than this, with a size-dependent rotation rate. We expand on previous work and show that the torsional oscillation signal seen in the supergranules tracks that obtained for normal modes. We also find that the amplitudes and lifetimes of the supergranulation are size dependent.

  4. Viscosity measurement techniques in Dissipative Particle Dynamics

    NASA Astrophysics Data System (ADS)

    Boromand, Arman; Jamali, Safa; Maia, Joao M.

    2015-11-01

    In this study two main groups of viscosity measurement techniques are used to measure the viscosity of a simple fluid using Dissipative Particle Dynamics, DPD. In the first method, a microscopic definition of the pressure tensor is used in equilibrium and out of equilibrium to measure the zero-shear viscosity and shear viscosity, respectively. In the second method, a periodic Poiseuille flow and start-up transient shear flow is used and the shear viscosity is obtained from the velocity profiles by a numerical fitting procedure. Using the standard Lees-Edward boundary condition for DPD will result in incorrect velocity profiles at high values of the dissipative parameter. Although this issue was partially addressed in Chatterjee (2007), in this work we present further modifications (Lagrangian approach) to the original LE boundary condition (Eulerian approach) that will fix the deviation from the desired shear rate at high values of the dissipative parameter and decrease the noise to signal ratios in stress measurement while increases the accessible low shear rate window. Also, the thermostat effect of the dissipative and random forces is coupled to the dynamic response of the system and affects the transport properties like the viscosity and diffusion coefficient. We investigated thoroughly the dependency of viscosity measured by both Eulerian and Lagrangian methodologies, as well as numerical fitting procedures and found that all the methods are in quantitative agreement.

  5. Comparative evaluation of aqueous humor viscosity.

    PubMed

    Davis, Kyshia; Carter, Renee; Tully, Thomas; Negulescu, Ioan; Storey, Eric

    2015-01-01

    To evaluate aqueous humor viscosity in the raptor, dog, cat, and horse, with a primary focus on the barred owl (Strix varia). Twenty-six raptors, ten dogs, three cats, and one horse. Animals were euthanized for reasons unrelated to this study. Immediately, after horizontal and vertical corneal dimensions were measured, and anterior chamber paracentesis was performed to quantify anterior chamber volume and obtain aqueous humor samples for viscosity analysis. Dynamic aqueous humor viscosity was measured using a dynamic shear rheometer (AR 1000 TA Instruments, New Castle, DE, USA) at 20 °C. Statistical analysis included descriptive statistics, unpaired t-tests, and Tukey's test to evaluate the mean ± standard deviation for corneal diameter, anterior chamber volume, and aqueous humor viscosity amongst groups and calculation of Spearman's coefficient for correlation analyses. The mean aqueous humor viscosity in the barred owl was 14.1 centipoise (cP) ± 9, cat 4.4 cP ± 0.2, and dog 2.9 cP ± 1.3. The aqueous humor viscosity for the horse was 1 cP. Of the animals evaluated in this study, the raptor aqueous humor was the most viscous. The aqueous humor of the barred owl is significantly more viscous than the dog (P < 0.0001). The aqueous humor viscosity of the raptor, dog, cat, and horse can be successfully determined using a dynamic shear rheometer. © 2014 American College of Veterinary Ophthalmologists.

  6. A Study of Oil Viscosity Mental Model

    NASA Astrophysics Data System (ADS)

    Albaiti; Liliasari; Sumarna, Omay; Abdulkadir Martoprawiro, Muhamad

    2017-02-01

    There is no study regarding on how to learn viscosity of the liquid (e.g. oil) by interconnecting macroscopic, sub-microscopic and symbolic levels. Therefore, the purpose of this research was to study the mental model of the oil viscosity. Intermolecular attractive force of oil constituent on the sub-microscopic level is depicted in the form of mental models. In this research, the viscosity data for some types of oil was measured by using Hoppler method. Viscosity of mineral oil SAE 20W-50, mineral oil SAE 15W-40 and synthetic oil SAE 10W-40 were 1.75, 1.31, and 1.03 Pa s, and the densities of these oils were 908.64, 885.04, and 877.02 kg/m3, respectively. The results showed that the greater density of the mineral oil that is assumed to be composed of linear chains of hydrocarbons, the longer the chain of hydrocarbon linear. Consequently, there are stronger the London force and greater the oil viscosity. The density and viscosity of synthetic oil are lower than that of both mineral oils. Synthetic oil structurally forms polymers with large branching. This structure affects a lower synthetic oil viscosity. This study contributes to construct a mental model of pre-service chemistry teachers.

  7. Effect of Viscosity on Growth Rates of Interchange Modes in Magnetic Inertial Fusion Plasmas

    NASA Astrophysics Data System (ADS)

    Morse, R. L.; Nachtrieb, R.

    1999-11-01

    Thermal insulating B fields in imploding MIF/MTF confinement systems, as in predecessor static wall confinement systems, must close in the confined plasma and, therefore, have unfavorable curvature for MHD interchange mode stability. Analytic inviscid estimates with typical compressed z-pinch fields Bth=1MG, plasma density n=3.e20 and radius a=1cm give max. m=0 mode growth rates, Gm, of order 1.e8s-1 with wavelengths Lz of .1a to .5a. Thermal conduction to the confining wall increases B there and Gm significantly, as Vekstein discusses in concluding in effect that such confinement would not be useful for fusion. These growth rates and mode forms are confirmed by two supporting compressible models(Freidberg/McCrory). Happily when viscosity(Braginskii) is included; G is reduced, esp. at longer wavelengths, Lz, with scaling Lz**-1, and viscosities of 1e2 to 1e4 poise for the example plasmas give Gm's of order 1.e7s-1 and less with realistic time dependent profiles. We conclude that these Gm's are consistent with significant fusion yields. This work was presented at the UCLA/DoE ICC conference, 3/3-6/97.

  8. Rotational Energy.

    ERIC Educational Resources Information Center

    Lockett, Keith

    1988-01-01

    Demonstrates several objects rolling down a slope to explain the energy transition among potential energy, translational kinetic energy, and rotational kinetic energy. Contains a problem from Galileo's rolling ball experiment. (YP)

  9. Rotational Energy.

    ERIC Educational Resources Information Center

    Lockett, Keith

    1988-01-01

    Demonstrates several objects rolling down a slope to explain the energy transition among potential energy, translational kinetic energy, and rotational kinetic energy. Contains a problem from Galileo's rolling ball experiment. (YP)

  10. Solar rotation.

    NASA Astrophysics Data System (ADS)

    Dziembowski, W.

    Sunspot observations made by Johannes Hevelius in 1642 - 1644 are the first ones providing significant information about the solar differential rotation. In modern astronomy the determination of the rotation rate is done in a routine way by measuring positions of various structures on the solar surface as well as by studying the Doppler shifts of spectral lines. In recent years a progress in helioseismology enabled determination of the rotation rate in the layers inaccessible for direct observations. There are still uncertainties concerning, especially, the temporal variations of the rotation rate and its behaviour in the radiative interior. We are far from understanding the observations. Theoretical works have not yet resulted in a satisfactory model for the angular momentum transport in the convective zone.

  11. A microfluidic device for simultaneous measurement of viscosity and flow rate of blood in a complex fluidic network

    PubMed Central

    Jun Kang, Yang; Yeom, Eunseop; Lee, Sang-Joon

    2013-01-01

    Blood viscosity has been considered as one of important biophysical parameters for effectively monitoring variations in physiological and pathological conditions of circulatory disorders. Standard previous methods make it difficult to evaluate variations of blood viscosity under cardiopulmonary bypass procedures or hemodialysis. In this study, we proposed a unique microfluidic device for simultaneously measuring viscosity and flow rate of whole blood circulating in a complex fluidic network including a rat, a reservoir, a pinch valve, and a peristaltic pump. To demonstrate the proposed method, a twin-shaped microfluidic device, which is composed of two half-circular chambers, two side channels with multiple indicating channels, and one bridge channel, was carefully designed. Based on the microfluidic device, three sequential flow controls were applied to identify viscosity and flow rate of blood, with label-free and sensorless detection. The half-circular chamber was employed to achieve mechanical membrane compliance for flow stabilization in the microfluidic device. To quantify the effect of flow stabilization on flow fluctuations, a formula of pulsation index (PI) was analytically derived using a discrete fluidic circuit model. Using the PI formula, the time constant contributed by the half-circular chamber is estimated to be 8 s. Furthermore, flow fluctuations resulting from the peristaltic pumps are completely removed, especially under periodic flow conditions within short periods (T < 10 s). For performance demonstrations, the proposed method was applied to evaluate blood viscosity with respect to varying flow rate conditions [(a) known blood flow rate via a syringe pump, (b) unknown blood flow rate via a peristaltic pump]. As a result, the flow rate and viscosity of blood can be simultaneously measured with satisfactory accuracy. In addition, the proposed method was successfully applied to identify the viscosity of rat blood, which circulates in a

  12. A microfluidic device for simultaneous measurement of viscosity and flow rate of blood in a complex fluidic network.

    PubMed

    Jun Kang, Yang; Yeom, Eunseop; Lee, Sang-Joon

    2013-01-01

    Blood viscosity has been considered as one of important biophysical parameters for effectively monitoring variations in physiological and pathological conditions of circulatory disorders. Standard previous methods make it difficult to evaluate variations of blood viscosity under cardiopulmonary bypass procedures or hemodialysis. In this study, we proposed a unique microfluidic device for simultaneously measuring viscosity and flow rate of whole blood circulating in a complex fluidic network including a rat, a reservoir, a pinch valve, and a peristaltic pump. To demonstrate the proposed method, a twin-shaped microfluidic device, which is composed of two half-circular chambers, two side channels with multiple indicating channels, and one bridge channel, was carefully designed. Based on the microfluidic device, three sequential flow controls were applied to identify viscosity and flow rate of blood, with label-free and sensorless detection. The half-circular chamber was employed to achieve mechanical membrane compliance for flow stabilization in the microfluidic device. To quantify the effect of flow stabilization on flow fluctuations, a formula of pulsation index (PI) was analytically derived using a discrete fluidic circuit model. Using the PI formula, the time constant contributed by the half-circular chamber is estimated to be 8 s. Furthermore, flow fluctuations resulting from the peristaltic pumps are completely removed, especially under periodic flow conditions within short periods (T < 10 s). For performance demonstrations, the proposed method was applied to evaluate blood viscosity with respect to varying flow rate conditions [(a) known blood flow rate via a syringe pump, (b) unknown blood flow rate via a peristaltic pump]. As a result, the flow rate and viscosity of blood can be simultaneously measured with satisfactory accuracy. In addition, the proposed method was successfully applied to identify the viscosity of rat blood, which circulates in a

  13. Viscosity of high-temperature iodine

    NASA Technical Reports Server (NTRS)

    Kang, Steve H.; Kunc, Joseph A.

    1991-01-01

    The viscosity coefficient of iodine in the temperature range 500 - 3000 K is calculated. Because of the low dissociation energy of the I2 molecules, the dissociation degree of the gas increases quickly with temperature, and I + I2 and I + I collisions must be taken into account in calculation of viscosity at temperatures greater than 1000 deg. Several possible channels for atom-atom interaction are considered, and the resulting collision integrals are averaged over all the important channels. It is also shown that the rigid-sphere model is inaccurate in predictions of the viscosity.

  14. Viscosity of high-temperature iodine

    NASA Technical Reports Server (NTRS)

    Kang, Steve H.; Kunc, Joseph A.

    1991-01-01

    The viscosity coefficient of iodine in the temperature range 500 - 3000 K is calculated. Because of the low dissociation energy of the I2 molecules, the dissociation degree of the gas increases quickly with temperature, and I + I2 and I + I collisions must be taken into account in calculation of viscosity at temperatures greater than 1000 deg. Several possible channels for atom-atom interaction are considered, and the resulting collision integrals are averaged over all the important channels. It is also shown that the rigid-sphere model is inaccurate in predictions of the viscosity.

  15. Viscosity studies of water based magnetite nanofluids

    SciTech Connect

    Anu, K.; Hemalatha, J.

    2016-05-23

    Magnetite nanofluids of various concentrations have been synthesized through co-precipitation method. The structural and topographical studies made with the X-Ray Diffractometer and Atomic Force Microscope are presented in this paper. The density and viscosity studies for the ferrofluids of various concentrations have been made at room temperature. The experimental viscosities are compared with theoretical values obtained from Einstein, Batchelor and Wang models. An attempt to modify the Rosensweig model is made and the modified Rosensweig equation is reported. In addition, new empirical correlation is also proposed for predicting viscosity of ferrofluid at various concentrations.

  16. Viscoseal performance with rarefied-gas sealant

    NASA Technical Reports Server (NTRS)

    Milligan, M. W.

    1973-01-01

    A fundamental study of viscoseals having a rarefied gas as the sealant was conducted. Both experimental and analytical investigations are reported. Three different analytical models were formulated and are described in detail. An experimental investigation was conducted on multiple grooved two-inch diameter viscoseals over a wide range of gas densities and shaft speeds up to 30,000 rpm. Comparisons are presented between actual viscoseal performance and the theoretical predictions for both sealing coefficient and net leakage parameters as functions of the degree of gas rarefication. Recommendations are presented for the use of the analytical models.

  17. Shear viscosity in the postquasistatic approximation

    SciTech Connect

    Peralta, C.; Rosales, L.; Rodriguez-Mueller, B.; Barreto, W.

    2010-05-15

    We apply the postquasistatic approximation, an iterative method for the evolution of self-gravitating spheres of matter, to study the evolution of anisotropic nonadiabatic radiating and dissipative distributions in general relativity. Dissipation is described by viscosity and free-streaming radiation, assuming an equation of state to model anisotropy induced by the shear viscosity. We match the interior solution, in noncomoving coordinates, with the Vaidya exterior solution. Two simple models are presented, based on the Schwarzschild and Tolman VI solutions, in the nonadiabatic and adiabatic limit. In both cases, the eventual collapse or expansion of the distribution is mainly controlled by the anisotropy induced by the viscosity.

  18. Bulk viscosity of superfluid hyperon stars

    SciTech Connect

    Gusakov, Mikhail E.; Kantor, Elena M.

    2008-10-15

    We calculate the bulk viscosity due to nonequilibrium weak processes in superfluid nucleon-hyperon matter of neutron stars. For that, the dissipative relativistic hydrodynamics, formulated eariler [M. E. Gusakov, Phys. Rev. D 76, 083001 (2007).] for superfluid mixtures, is extended to the case when both nucleons and hyperons are superfluid. It is demonstrated that in the most general case (when neutrons, protons, {lambda}, and {sigma}{sup -} hyperons are superfluid), nonequilibrium weak processes generate 16 bulk viscosity coefficients, with only three of them being independent. In addition, we correct an inaccuracy in a widely used formula for the bulk viscosity of nonsuperfluid nucleon-hyperon matter.

  19. Viscosity studies of water based magnetite nanofluids

    NASA Astrophysics Data System (ADS)

    Anu, K.; Hemalatha, J.

    2016-05-01

    Magnetite nanofluids of various concentrations have been synthesized through co-precipitation method. The structural and topographical studies made with the X-Ray Diffractometer and Atomic Force Microscope are presented in this paper. The density and viscosity studies for the ferrofluids of various concentrations have been made at room temperature. The experimental viscosities are compared with theoretical values obtained from Einstein, Batchelor and Wang models. An attempt to modify the Rosensweig model is made and the modified Rosensweig equation is reported. In addition, new empirical correlation is also proposed for predicting viscosity of ferrofluid at various concentrations.

  20. Factors affecting the viscosity of sodium hypochlorite and their effect on irrigant flow.

    PubMed

    Bukiet, F; Soler, T; Guivarch, M; Camps, J; Tassery, H; Cuisinier, F; Candoni, N

    2013-10-01

    To assess the influence of concentration, temperature and surfactant addition to a sodium hypochlorite solution on its dynamic viscosity and to calculate the corresponding Reynolds number to determine the corresponding flow regimen. The dynamic viscosity of the irrigant was assessed using a rotational viscometer. Sodium hypochlorite with concentrations ranging from 0.6% to 9.6% was tested at 37 and 22 °C. A wide range of concentrations of three different surfactants was mixed in 2.4% sodium hypochlorite for viscosity measurements. The Reynolds number was calculated under each condition. Data were analysed using two-way anova. There was a significant influence of sodium hypochlorite concentration (P < 0.001) and temperature (P < 0.001) on dynamic viscosity: the latter significantly increased with sodium hypochlorite concentration and decreased with temperature. A significant influence of surfactant concentration on dynamic viscosity (P < 0.001) occurred, especially for high surfactant concentrations: 6.25% for benzalkonium chloride, 15% for Tween 80 and 6.25% for Triton X-100. Reynolds number values calculated for a given flow rate (0.14 mL s(-1)), and root canal diameter (sizes 45 and 70) clearly qualified the irrigant flow regimen as laminar. Dynamic viscosity increased with sodium hypochlorite and surfactant concentration but decreased with temperature. Under clinical conditions, all viscosities measured led to laminar flow. The transition between laminar and turbulent flow may be reached by modifying different parameters at the same time: increasing flow rate and temperature whilst decreasing irrigant viscosity by adding surfactants with a high value of critical micellar concentration. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  1. [Correlation between retention force of experimental plates and viscosity of experimental fluids].

    PubMed

    Mladenović, Dragan; Stanković, Dragutin; Stanković, Jasmina; Stanković, Saša; Mladenović, Lidija

    2011-01-01

    Saliva viscosity plays a significant role in the biophysical segment of the total retention potential of total dentures. The aim of the paper was to establish the dependence of dynamic retention force of experimental plates on experimental fluid viscosity and especially time dependence of these parameters, following at the same time relative changes of the distance between the experimental plate and dentures support established by the dislocation of the experimental plate in both directions. For experimental verification we used an original device with the aim to enable in vivo simulation on the phantom made of the upper total denture prosthesis support and experimental plate. The experiment consisted of two parts. In the first part we determined the value of the dynamic retention force with plates without and with achieved ventilation effect. In the second part we determined time dependence of the dynamic retention force of experimental plates on the viscosity of experimental fluids that had been priorly determined on identical samples (8 ml of experimental fluid samples) using a rotational viscometer (Haake RV-12) with a sensor (MV, Germany). Under the conditions of variable viscosity rates of seven experimental fluids (from 0.02 to 1309.04 mPa s), we registered the time dependence of dynamic retention force of the experimental plate related to fluid viscosity during the action of the continual dislocating force of the separating directions. In addition, the maximal height of the dislocation of the experimental plate was registered. The dynamic retention force, manifested by the separating direction of the experimental plate dislocation, was increased concurrently with increased viscosity. The increase of dynamic retention force depends directly on medium viscosity. Close border values of fluid viscosity above the investigated ones, the impossibility of experimental layer thinning and the decrease of distance height probably influence the onset of separating

  2. Effect of interfacial energy on the viscosities of two-phase mixtures—A physical modeling approach

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Sichen, Du; Seetharaman, S.

    2001-02-01

    With a view to understanding the viscosities of metal emulsions in viscous slags, the present work was carried out to study the phenomena underlying the viscous flow in a two-phase mixture with widely differing viscosities. Experimental study was carried out to determine the effective viscosities of emulsions of silicone oils of known viscosities (345 and 1010 mPa · s at 293 K) with small amounts of water evenly distributed in the same. The viscosities of these emulsions were measured at a constant temperature by the rotating-cylinder method. The uniformity of the preparation of the emulsions was confirmed by the reproducibility of the results. The measured viscosities were generally found to be independent of the torque under the experimental conditions, so that the two-phase mixture could be considered as a Newtonian liquid. The variation of viscosities with temperature and the effect of the addition of a surface-active substance were also studied in this work. The viscosities were found to be higher than those of both pure water and silicone oil. The experimental results were used to examine the applicabilities of the theoretical models developed by Einstein, Taylor, and Oldroyd. It was found that interfacial energy would play an important role in the viscous flow of the two-liquid mixture.

  3. Calculations of rotational flows using stream function

    NASA Technical Reports Server (NTRS)

    Hafez, M.; Yam, C.; Tang, K.; Dwyer, H.

    1989-01-01

    The stream function equation is solved for steady two-dimensional (and axisymmetric) rotational flows. Both finite differences and finite volumes discretization techniques are studied, using generalized body fitted coordinates and unstructured staggered grids, respectively. For inviscid transonic flows, a new artificial viscosity scheme which does not produce any artificial vorticity is introduced, for the stability of the mixed flow calculations and for capturing shocks. The solution of Euler equations, in primitive variables, are also considered. The effects of the artificial viscosity and numerical boundary conditions on the total enthalpy and the vorticity distributions are demonstrated.

  4. Pinch me - I'm fusing! Fusion Power - what is it? What is a z pinch? And why are z-pinches a promising fusion power technology?

    SciTech Connect

    DERZON,MARK S.

    2000-03-01

    The process of combining nuclei (the protons and neutrons inside an atomic nucleus) together with a release of kinetic energy is called fusion. This process powers the Sun, it contributes to the world stockpile of weapons of mass destruction and may one day generate safe, clean electrical power. Understanding the intricacies of fusion power, promised for 50 years, is sometimes difficult because there are a number of ways of doing it. There is hot fusion, cold fusion and con-fusion. Hot fusion is what powers suns through the conversion of mass energy to kinetic energy. Cold fusion generates con-fusion and nobody really knows what it is. Even so, no one is generating electrical power for you and me with either method. In this article the author points out some basic features of the mainstream approaches taken to hot fusion power, as well as describe why z pinches are worth pursuing as a driver for a power reactor and how it may one day generate electrical power for mankind.

  5. Dynamical influences on the moment of inertia tensor from lateral viscosity variations inferred from seismic tomographic models

    NASA Technical Reports Server (NTRS)

    Zhang, Shuxia; Yuen, David A.

    1994-01-01

    We have investigated the influences of lateral variations of viscosity on the moment of inertia tensor from viscous flows due to the density anomalies in the mantle inferred from seismic tomographic models. The scaling relations between the density and the seismic anomalies is taken as either a constant or a function increasing with depth in accord with the recent high-pressure experimental studies. The viscosity is taken as an exponential function of the 3D density anomaly. In models with an isoviscous background, the effects on the perturbed moment of inertia tensor from the lateral viscosity variations are smaller than those due to variations in the radial viscosity profiles. In mantle models with a background viscosity increasing with depth, the influences of the lateral viscosity variations are significant. The most striking feature in the latter case is that the two off-diagonal elements delta I(sub xz) and delta I(sub yz) in the inertia tensor exhibit greatest sensitivity to lateral variations of the viscosity. While the other elements of the inertia change by only about a few tens of percent in the range of lateral viscosity contrast considered (less than 300), delta I(sub xz) and delta I(sub yz) can vary up to 40 times even with a change in sign, depending on the radial viscosity stratification and the location of the strongest lateral variations. The increase in the velocity-density scaling relation with depth can reduce the influences of the lateral viscosity variations, but it does not change the overall sensitive nature of delta I(sub xz) and delta I(sub yz). This study demonstrates clearly that the lateral viscosity variations, especially in the upper mantle, must be considered in the determination of long-term polar wander, since the variations in the delta I(sub xz) and delta I(sub yz) terms are directly responsible for exciting rotational movements.

  6. Dynamical influences on the moment of inertia tensor from lateral viscosity variations inferred from seismic tomographic models

    NASA Technical Reports Server (NTRS)

    Zhang, Shuxia; Yuen, David A.

    1994-01-01

    We have investigated the influences of lateral variations of viscosity on the moment of inertia tensor from viscous flows due to the density anomalies in the mantle inferred from seismic tomographic models. The scaling relations between the density and the seismic anomalies is taken as either a constant or a function increasing with depth in accord with the recent high-pressure experimental studies. The viscosity is taken as an exponential function of the 3D density anomaly. In models with an isoviscous background, the effects on the perturbed moment of inertia tensor from the lateral viscosity variations are smaller than those due to variations in the radial viscosity profiles. In mantle models with a background viscosity increasing with depth, the influences of the lateral viscosity variations are significant. The most striking feature in the latter case is that the two off-diagonal elements delta I(sub xz) and delta I(sub yz) in the inertia tensor exhibit greatest sensitivity to lateral variations of the viscosity. While the other elements of the inertia change by only about a few tens of percent in the range of lateral viscosity contrast considered (less than 300), delta I(sub xz) and delta I(sub yz) can vary up to 40 times even with a change in sign, depending on the radial viscosity stratification and the location of the strongest lateral variations. The increase in the velocity-density scaling relation with depth can reduce the influences of the lateral viscosity variations, but it does not change the overall sensitive nature of delta I(sub xz) and delta I(sub yz). This study demonstrates clearly that the lateral viscosity variations, especially in the upper mantle, must be considered in the determination of long-term polar wander, since the variations in the delta I(sub xz) and delta I(sub yz) terms are directly responsible for exciting rotational movements.

  7. Coherent structures and anomalous transport in reversed field pinch plasmas

    NASA Astrophysics Data System (ADS)

    Antoni, V.; Drake, J. R.; Spada, E.; Spolaore, M.; Vianello, N.; Bergsåker, H.; Cavazzana, R.; Cecconello, M.; Martines, E.; Serianni, G.

    2006-02-01

    The results leading to the identification of coherent structures emerging from the background turbulence in the edge region of the reversed field pinch experiments EXTRAP-T2R and RFX are reviewed. These structures have traits of vortices in velocity field and blobs in density, and the reconstruction of their spatial structure and of their time evolution is discussed focusing on the analysis tools applied. The role of these structures in the particle anomalous transport is addressed, showing that their collisions can contribute up to 50% the total particle losses.This process is shown to be responsible for bursts in particle flux and it is found to set a characteristic collision time, which is in agreement with the statistical properties of laminar times for particle flux bursts.

  8. Lower hybrid accessibility in a large, hot reversed field pinch

    SciTech Connect

    Dziubek, R.A.; Harvey, R.W.; Hokin, S.A.; Uchimoto, E.

    1995-11-01

    Accessibility and damping of the slow wave in a reversed field pinch (RFP) plasma is investigated theoretically, using projected Reversed Field Experiment (RFX) plasma parameters. By numerically solving the hot plasma dispersion relation, regions of propagation are found and the possibility of mode conversion is analyzed. If the parallel index of refraction of the wave is chosen judiciously at the edge of the plasma, the slow wave is accessible to a target region located just inside the reversal surface without mode conversion. Landau damping is also optimized in this region. A representative fast electron population is then added in order to determine its effect on accessibility and damping. The presence of these electrons, whose parameters were estimated by extrapolation of Madison Symmetric Torus (MST) data, does not affect the accessibility of the wave. However, the initial phase velocity of the wave needs to be increased somewhat in order to maintain optimal damping in the target zone.

  9. Anomalous transport theory for the reversed field pinch

    SciTech Connect

    Terry, P.W.; Hegna, C.C; Sovinec, C.R.

    1996-09-01

    Physically motivated transport models with predictive capabilities and significance beyond the reversed field pinch (RFP) are presented. It is shown that the ambipolar constrained electron heat loss observed in MST can be quantitatively modeled by taking account of the clumping in parallel streaming electrons and the resultant self-consistent interaction with collective modes; that the discrete dynamo process is a relaxation oscillation whose dependence on the tearing instability and profile relaxation physics leads to amplitude and period scaling predictions consistent with experiment; that the Lundquist number scaling in relaxed plasmas driven by magnetic turbulence has a weak S{sup {minus}1/4} scaling; and that radial E{times}B shear flow can lead to large reductions in the edge particle flux with little change in the heat flux, as observed in the RFP and tokamak. 24 refs.

  10. Instability Control in a Staged Z-pinch

    SciTech Connect

    WESSEL, Frank J

    2011-04-22

    A \\Staged Z-Pinch is a fusion-energy concept in which stored-electric energy is first converted into plasma-liner-kinetic energy, and then transferred to a coaxialtarget plasma [H. U. Rahman, F. J. Wessel, and N. Rostoker, Phys. Rev. Lett. 74, p. 714(1996)]. Proper choice of the liner and target materials, and their initial radii and mass densities, leads to dynamic stabilization, current amplification, and shock heating of the target. Simulations suggest that this configuration has merit as a alternative inertial-confinement-fusion concept, and may provide an energy release exceeding thermonuclear break-even, if tested on one of many newer pulsed power systems, for example those located at Sandia National Laboratories.

  11. Experimental astrophysics with high power lasers and Z pinches

    SciTech Connect

    Remington, B A; Drake, R P; Ryutov, D D

    2004-12-10

    With the advent of high energy density (HED) experimental facilities, such as high-energy lasers and fast Z-pinch, pulsed-power facilities, mm-scale quantities of matter can be placed in extreme states of density, temperature, and/or velocity. This has enabled the emergence of a new class of experimental science, HED laboratory astrophysics, wherein the properties of matter and the processes that occur under extreme astrophysical conditions can be examined in the laboratory. Areas particularly suitable to this class of experimental astrophysics include the study of opacities relevant to stellar interiors; equations of state relevant to planetary interiors; strong shock driven nonlinear hydrodynamics and radiative dynamics, relevant to supernova explosions and subsequent evolution; protostellar jets and high Mach-number flows; radiatively driven molecular clouds and nonlinear photoevaporation front dynamics; and photoionized plasmas relevant to accretion disks around compact objects, such as black holes and neutron stars.

  12. The effect of shaping on Reversed Field Pinch dynamics

    NASA Astrophysics Data System (ADS)

    Chahine, Robert; Morales, Jorge A.; Schneider, Kai; Bos, Wouter J. T.

    2016-10-01

    Reversed Field Pinch fusion devices (RFPs) are inevitably plagued by magnetohydrodynamic (MHD) instabilities. High resolution numerical simulations of fully nonlinear visco-resistive magnetohydrodynamics using a Fourier pseudo-spectral method with volume penalization [Morales et al. JCP, 2014] are performed. Results of RFP simulations in toroidal geometry were reported in [Morales et al. PPCF, 2014]. Here we consider a cylindrical domain with elliptical cross-section for different aspect ratios. The results illustrate a notable influence of the shape of the cross-section on the nonlinear dynamics of RFPs. The axial mode-spectrum is qualitatively changed in cylinders with elliptic cross-section. The results suggest that shaping could change, and possibly improve the confinement of RFPs. It is certainly possible that specific helical modes can be promoted, approaching thereby a QSH state. Support by the French Research Federation for Fusion Studies within the framework of the European Fusion Development Agreement (EFDA) is thankfully acknowledged.

  13. A kind of fast shutter for Z pinch diagnosis device

    NASA Astrophysics Data System (ADS)

    Wang, Liangping; Zhang, Xinjun; Sun, Tieping; Mao, Wentin

    2016-09-01

    A kind of fast shutter for protecting the diagnosis devices in Z pinch experiments is introduced in this paper. The shutter is composed of a pulling rod, a magnetic core, and a solenoid. Different from the traditional coils which were used at the voltage of 220 V, the solenoid we used must endure the high voltage of 5-10 kV and the deformation which maybe caused by the 5-10 T intense magnetic field. A creative configuration for the solenoid is developed including the winding guide, insulating sleeve, and stainless-steel sleeve. The experimental results show that the configuration of the solenoid is effective. The velocity of the valve is nearly 19 m/s and the time jitter of the shutdown is within 75 μs.

  14. Physics of reversed-field pinch profile sustainment

    SciTech Connect

    Moses, R.W.

    1984-01-01

    A description of the Reversed-Field Pinch (RFP) is given, emphasizing the necessity of a magnetohydrodynamic (MHD) or kinetic process to sustain field reversal. Three sustainment mechanisms are reviewed: the MHD dynamo, the tangled discharge model, and nonlocal resistivity. A slab model of steady (ohmic) states is described. A relationship between ohmic state wave numbers and the minimum amplitude of nonsymmetric field components is given. If ohmic states are the sole source of the sustainment process, their wave lengths are probably much longer than the minor diameter of the plasma. Otherwise field asymmetries would exceed those observed in experiments. It is noted that internal field data are still limited, restricting the generality of our comments.

  15. Gyrokinetic studies of microinstabilities in the reversed field pinch

    SciTech Connect

    Carmody, D.; Pueschel, M. J.; Terry, P. W.

    2013-05-15

    An analytic equilibrium, the Toroidal Bessel Function Model, is used in conjunction with the gyrokinetic code GYRO to investigate the nature of microinstabilities in a reversed field pinch plasma. The effect of the normalized electron plasma pressure β on the characteristics of the microinstabilities is studied. At a β of 4.5%, a transition between an ion temperature gradient (ITG) and a microtearing mode is observed. Suppression of the ITG mode occurs as in the tokamak, through coupling to shear Alfvén waves, with a critical β for stability higher than its tokamak equivalent due to a shorter parallel connection length. A steep dependence of the microtearing growth rate on the temperature gradient suggests high profile stiffness. There is evidence for a collisionless microtearing mode. The properties of this mode are investigated, and it is found that electron curvature drift plays an important role in the instability.

  16. Axial Plasma Jet Characterization on a Microsecond X-Pinch

    NASA Astrophysics Data System (ADS)

    Jaar, G. S.; Appartaim, R. K.

    2016-10-01

    The plasma jets generated from a two wire x-pinch have been studied with current quarter period of 1 μs. Wires of tungsten, aluminum, and titanium of 25-100 μm thicknesses have been exploded with a peak current value of 350kA. The plasma has been characterized using Nd:YAG based schlieren photography, time-resolved optical photography, x-ray photodiode detector, and a flat crystal x-ray spectrometer. The schlieren photographs enable determination of the evolution and velocity of the jets. Plasma temperature and density measurements at the crossing point will also be reported from the crystal spectrometer. This research is supported by the US DOE.

  17. Restoration of pinch in intrinsic muscles of the hand.

    PubMed

    Lee, Steve K; Wisser, Jamie R

    2012-02-01

    The primary intrinsic muscles responsible for key and tip pinch are the adductor pollicis, first dorsal interosseous and flexor pollicis brevis muscles. Numerous conditions can lead to their dysfunction. Non-operative treatment consists of exercises of the compensating extensor pollicis longus and flexor pollicis longus muscles and use of adaptive devices, such as larger grips. Operative treatments include tendon transfers and joint fusions. The most common tendon transfer procedures include transfering of the extensor carpi radialis brevis to the adductor pollicis muscle or transfering of the abductor pollicis longus to the first dorsal interosseous muscle. Both require use of extension tendon grafts. In cases of joint instability or arthrosis, arthrodesis of the thumb and index finger MP or IP joints, alone or in combination, may be indicated. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. A Compact Pulsed Power Generator for Capillary Pinch Experiments

    NASA Astrophysics Data System (ADS)

    Shukla, R.; Pulsed Power Group

    2006-01-01

    A compact pulsed power system is designed for conducting capillary pinch experiments for production of coherent electromagnetic radiations. The reported Pulsed power system is made very compact as well as portable by using solid dielectric pulse forming line. The system consists of a tesla transformer, which is of helical secondary and cylindrical-sheet single-turn primary. Tesla charges a pulse forming line made of cascade of 50 ohm transition lines, which are of high wattage as well as high voltage ratings under pulsed operation. The net impedance of this cable cascade is such that it is matched for a designed load, which is designed to operate at 250kV for 100ns pulse duration.

  19. Oscillating field current drive for reversed field pinch discharges

    SciTech Connect

    Schoenberg, K.F.; Gribble, R.F.; Baker, D.A.

    1984-06-01

    Oscillating Field Current Drive (OFCD), also known as F-THETA pumping, is a steady-state current-drive technique proposed for the Reversed Field Pinch (RFP). Unlike other current-drive techniques, which employ high-technology, invasive, and power intensive schemes using radio frequency or neutral particle injection, F-THETA pumping entails driving the toroidal and poloidal magnetic field circuits with low-frequency (audio) oscillating voltage sources. Current drive by this technique is a consequence of the strong nonlinear plasma coupling in the RFP. Because of its low frequency and efficient plasma coupling, F-THETA pumping shows excellent promise as a reactor-relevant current-drive technique. A conceptual and computational study of this concept, including its experimental and reactor relevance, is explored in this paper.

  20. Neoclassical transport in the helical Reversed-field pinch

    NASA Astrophysics Data System (ADS)

    Spizzo, Gianluca; Gobbin, Marco; Marrelli, Lionello; White, Roscoe B.

    2010-11-01

    Test particle evaluation of the diffusion coefficient in a fusion plasma in the reversed-field pinch (RFP) configuration shows distinct similarities with Stellarators when the plasma spontaneously evolves towards a helical shape with reduced magnetic chaos. In particular, we recover the classical Tokamak and Stellarator transition from the banana to the plateau and Pfirsch-Schlüter regimes. The almost total absence of helically trapped (``superbanana'') particles with the values of q typical of the RFP (|q| < 0.16) and at the levels of helical deformation seen in experiment (Bh/B = 10%) causes transport to be proportional to collision frequency (at low collisions). This fact excludes the possibility that the minimum conceivable transport could be inversely proportional to collision frequency, which is typical of un-optimized Stellarators. This result strengthens the perspectives of the helical RFP as a fusion configuration.

  1. Conceptual Design of a Z-Pinch Fusion Propulsion System

    NASA Technical Reports Server (NTRS)

    Adams, Robert; Polsgrove, Tara; Fincher, Sharon; Fabinski, Leo; Maples, Charlotte; Miernik, Janie; Stratham, Geoffrey; Cassibry, Jason; Cortez, Ross; Turner, Matthew; hide

    2010-01-01

    This slide presentation reviews a project that aims to develop a conceptual design for a Z-pinch thruster, that could be applied to develop advanced thruster designs which promise high thrust/high specific impulse propulsion. Overviews shows the concept of the design, which use annular nozzles with deuterium-tritium (D-T) fuel and a Lithium mixture as a cathode, Charts show the engine performance as a function of linear mass, nozzle performance (i.e., plasma segment trajectories), and mission analysis for possible Mars and Jupiter missions using this concept for propulsion. Slides show views of the concepts for the vehicle configuration, thrust coil configuration, the power management system, the structural analysis of the magnetic nozzle, the thermal management system, and the avionics suite,

  2. Shear-Limited Diffusion and Viscosity: Experiments and Theory

    NASA Astrophysics Data System (ADS)

    Driscoll, C. Fred

    2001-10-01

    Experiments and theory on collisional diffusion and viscosity demonstrate enhanced transport in the 2D bounce-averaged regime, limited by shear in the plasma rotation. The experiments are performed on relatively quiescent pure-ion or pure electron plasma columns, where the shear in the drift rotation ωE (r) can be controlled accurately. For long plasma columns, we measure test particle diffusion(F. Anderegg, et al.), Phys. Rev. Lett. 78, 2128 (1997). and bulk viscosity(J.M. Kriesel and C.F. Driscoll, submitted to Phys. Rev. Lett. (2001).) coefficients which quantitatively agree with recent 3D theories(D.H.E. Dubin, Phys. Plasmas 5), 1688 (1998). of E × B drift collisions with impact parameters in the range rc < ρ < λ_D. In general, this transport is substantially greater than would be expected for velocity-scattering collisions with ρ < r_c. For finite plasma length L_p, thermal particles may bounce axially many times before rotational shear separates them in θ and this number of bounces Nb ≡ ( barv / 2L_p) / (r ; partial ωE / partial r) characterizes the approach to the 2D bounce-averaged regime. Experiments measuring electron viscosity coefficients and separate experiments measuring tagged ion diffusion coefficients each show transport enhancements up to 100×, scaling quantitatively as Nb over the range 1 < Nb < 10^2. In the zero-shear limit of Nb arrow ∞ , theory treats the particles as z-averaged rods of charge undergoing 2D E × B drift dynamics. For this case, Taylor and McNamara showed that Bohm-like diffusion results from large-scale thermally-excited ``Dawson-Okuda'' vortices. More recently, Dubin(D.H.E. Dubin and D.Z. Jin, Phys. Lett. A 284), 112 (2001). analyzed the 2D test-particle diffusion with applied background shear, showing that the particle diffusion decreases with increasing shear. Overall, this new theory gives fair quantitative agreement with the diffusion experiments from the 3D (or high shear) regime with Nb <= 1 to the 2D (or

  3. Electrically rotating suspended films of polar liquids

    NASA Astrophysics Data System (ADS)

    Shirsavar, R.; Amjadi, A.; Tonddast-Navaei, A.; Ejtehadi, M. R.

    2011-02-01

    Controlled rotation of a suspended soap water film, simply generated by applying an electric field, has been reported recently. The film rotates when the applied electric field exceeds a certain threshold. In this study, we investigate the phenomenon in films made of a number of other liquids with various physical and chemical properties. Our measurements show that the intrinsic electrical dipole moments of the liquid molecules seems to be vital for the corresponding film rotation. All the investigated rotating liquids have a molecular electric dipole moment of above 1 Debye, while weakly polar liquids do not rotate. However, the liquids investigated here cover a wide range of physical parameters (e.g. viscosity, density, conductivity, etc.). So far, no significant correlation has been observed between the electric field thresholds and macroscopic properties of the liquids.

  4. Charger 1: A New Facility for Z-Pinch Research

    NASA Technical Reports Server (NTRS)

    Taylor, Brian; Cassibry, Jason; Cortez, Ross; Doughty, Glen; Adams, Robert; DeCicco, Anthony

    2017-01-01

    Charger 1 is a multipurpose pulsed power laboratory located on Redstone Arsenal, with a focus on fusion propulsion relevant experiments involving testing z-pinch diodes, pulsed magnetic nozzle and other related physics experiments. UAH and its team of pulsed power researchers are investigating ways to increase and optimize fusion production from Charger 1. Currently the team has reached high-power testing. Due to the unique safety issues related to high power operations the UAH/MSFC team has slowed repair efforts to develop safety and operations protocols. The facility is expected to be operational by the time DZP 2017 convenes. Charger 1 began life as the Decade Module 2, an experimental prototype built to prove the Decade Quad pinch configuration. The system was donated to UAH by the Defense Threat Reduction Agency (DRTA) in 2012. For the past 5 years a UAH/MSFC/Boeing team has worked to refurbish, assemble and test the system. With completion of high power testing in summer 2017 Charger 1 will become operational for experimentation. Charger 1 utilizes a Marx Bank of 72 100-kV capacitors that are charged in parallel and discharged in series. The Marx output is compressed to a pulse width of approximately 200 ns via a pulse forming network of 32 coaxial stainless steel tubes using water as a dielectric. After pulse compression a set of SF6 switches are triggered, allowing the wave front to propagate through the output line to the load. Charger 1 is capable of storing 572-kJ of energy and time compressing discharge to less than 250 ns discharge time producing a discharge of about 1 TW of discharge with 1 MV and 1 MA peak voltage and current, respectively. This capability will be used to study energy yield scaling and physics from solid density target as applied to advanced propulsion research.

  5. Instability heating of solid-fiber Z pinches

    SciTech Connect

    Riley, Jr., Ronald Alan

    1994-02-01

    The Los Alamos High Density Z Pinch-II (HDZP-II) facility is used to study the dynamics of z-pinch plasmas generated from solid fibers of deuterated polyethylene CD2 with a range in radii of 3--60 μm. HDZP-II is a pulsed-power generator that delivers a current that rises to 700 kA in 100 ns through an inductive load. A multiframe circular schlieren records the evolution of the shape and size of the plasma on seven images taken at 10-ns intervals. These circular-schlieren images show very strong m=0 instability at the onset of current and a rapid radial expansion of the plasma. No higher-order instabilities are observed. An interferometer is used to infer the electron density and electron line density, giving a measure of the fraction of plasma contained within the outline of the circular-schlieren image at one time during the multiframe sequence. A three-channel x-ray crystal-reflection spectrometer provides the time-resolved, spatially-averaged electron temperature. The magnitude of the x-ray emission at these energies also gives qualitative information about the electron temperature and density at late times. A lower bound on the ion temperature is inferred from the particle pressure needed to balance the magnetic field pressure. The ion temperature rose above that of the electrons, strongly suggesting an additional heating term that puts energy directly into the ions. An ion heating term is proposed to explain the observed rapid radial expansion and elevated ion temperatures. This heating term is based on the assumption that the observed m=0 instabilities reconnect, enclosing magnetic flux which degenerates into turbulence in the plasma. A 0-D simulation is developed to investigate the relevance of different physical models to the data presented.

  6. Z-pinch modeling at Sandia National Laboratories

    SciTech Connect

    Hussey, T.W.; Matzen, M.K.; Roderick, N.F.

    1989-01-01

    The recent emphasis of the Sandia National Laboratories fast Z-pinch effort has been to utilize an imploding gas puff to produce the pump radiation for a photoionization-pumped soft x-ray laser. Because of their potential for utilizing the cylindrical convergence of a fast Z-pinch, we use hollow, coaxial, cylindrical targets to stagnate the implosion. The kilovolt component of radiation produced by this stagnation is the photoionizing pump source for the lasant material that is inside the cylinder. Such a system requires a detailed understanding of the dynamics of both the target and the imploding gas puff as well as their radiative properties. In recent years at Sandia we have studied a number of aspects of this process theoretically, which we describe here. We have considered large scale length non-uniformities resulting from flaring of the gas puff that lead to nonuniform target closure, and shorter wavelength non-uniformities resulting from the hydromagnetic Rayleigh-Taylor instability. More recently, we have emphasized the profound effect of ''radiation collapse'' of the imploding annular plasma before it reaches the target. This process, which varies considerably with gas puff material and mass (and, therefore, implosion energy), alters density gradient and radiation preheat during the run-in, greatly affecting target dynamics. In addition, we have developed detailed designs for these central targets, which are found to levy severe requirements on gas puff implosion performance. The feasibility of meeting these requirements which may be ameliorated by increased driver energy, is discussed. 32 refs., 9 figs.

  7. Z-Pinch Drivers for Shock Physics Research

    SciTech Connect

    Asay, J.; Bernard, M.; Clark, B.; Fleming, K.; Hall, C.; Holland, K.; McDaniel, D.; Spielman, R.; Stygar, W.; Trott, W.

    1998-10-13

    The recent development of Z pinch drivers for producing intense radiation envkomn~ enables study of physical and mechanical properties of condensed materials in regimes previously inaccessible in the Mm-am-y. With Z pinch radiation sources, it is possible fo subject mm-sized sampies to pianar compressions of a fe w Mbar. Tie-resolved velocity interferometry was used to perform the first shock loading and unloading profiles in Al and Be for ablatively driven shock$s to 3 Mbar and the first iseritropic loading of iron specimens to 300 War. A principai goai of our shock physics program is to establish a capability to make accurats eqwion of state measurements on the Z pulsed radiation source. The Z accelerator is a source of intense radntion, which can be used to drive ablative shocks for E(X$ studies. With this source, ablative muki-Mbar shocks can be produced to study materials over the range of interest to both weapons and ICF physics programs. In developing the capability to diagnose these types of studies on Z, techniques commonly used in conventional impact generated experiments were implemented. The primary diagnostic presently being used for this work is ve"!ocity interferoinetry, VL%4R, [2] which not only provides Hugoniot particle velocity measurements, but also measurements of non-shock EOS measummenu,, such as isentropic compression. In addition to VKSAR capability, methods for measuring shock velocity have also been developed for shock studies on Z. When used in conjunction with the Rankine-Hugoniot jump conditions, material response at high temperatures and pressures can be inferred. The next section discusses the basic approach for conducting EOS experiments on Z for both shock loading and istmtropic compression on the Z accelerator.

  8. Magnetohydrodynamic Simulation of Solid-Deuterium - Z-Pinch Experiments

    NASA Astrophysics Data System (ADS)

    Sheehey, Peter Trogdon

    Solid-deuterium-initiated Z-pinch experiments are numerically simulated using a two-dimensional resistive magnetohydrodynamic model, which includes many important experimental details, such as "cold-start" initial conditions, thermal conduction, radiative energy loss, actual discharge current vs. time, and grids of sufficient size and resolution to allow realistic development of the plasma. The alternating -direction-implicit numerical technique used meets the substantial demands presented by such a computational task. Simulations of fiber-initiated experiments show that when the fiber becomes fully ionized (at a time depending on current ramp and fiber thickness), rapidly developing m = 0 instabilities, which originated in the coronal plasma generated from the ablating fiber, drive intense non-uniform heating and rapid expansion of the plasma column. The possibility that inclusion of additional physical effects would improve stability is explored. Finite-Larmor-radius-ordered Hall and diamagnetic pressure terms in the magnetic field evolution equation, corresponding energy equation terms, and separate ion and electron energy equations are included; these do not change the basic results. Model diagnostics, such as shadowgrams and interferograms, generated from simulation results, are in good agreement with experiment. Two alternative experimental approaches are explored: high-current magnetic implosion of hollow cylindrical deuterium shells, and "plasma -on wire" (POW) implosion of low-density plasma onto a central deuterium fiber. By minimizing instability problems, these techniques may allow attainment of higher temperatures and densities than possible with bare fiber-initiated Z -pinches. Conditions for significant D-D or D-T fusion neutron production may be realizable with these implosion -based approaches.

  9. Viscosity and Shear Flows in Magnetized Dusty Plasmas

    NASA Astrophysics Data System (ADS)

    Romero-Talamas, C. A.; Bates, E. M.; Birmingham, W. J.; Rivera, W. F.; Takeno, J.; Knop, S.

    2015-11-01

    Magnetized dusty plasma experiments are planned at the Dusty Plasma Laboratory of the University of Maryland, Baltimore County (UMBC), to investigate E x B rotation with dust of at least 500 nm in diameter. At this size, individual particles can be tracked and viscosity, shear flow, and temperature can be measured directly using a methodology similar to that used for linear shear flow configurations [Feng et al. PRL 109, 185002 (2012)]. The experiments are planned with a specially designed Bitter-type magnet that can be configured to achieve up to 10 T for at least 10 seconds, to minutes, with much longer operation times at lower fields also possible. At the highest field, the dust will be fully magnetized and thus we aim to achieve direct E x B rotation of the dust (and not just by ion drag). The motivation for these experiments comes from observations of electron and ion temperatures in excess of 100 eV in E x B rotating plasmas [R. Reid et al. Phys. Plasmas 21, 063305 (2014)]. The experimental setup and planned diagnostics for the magnetized dusty plasma are presented.

  10. MODELING OF DIFFERENTIAL ROTATION IN RAPIDLY ROTATING SOLAR-TYPE STARS

    SciTech Connect

    Hotta, H.; Yokoyama, T.

    2011-10-10

    We investigate differential rotation in rapidly rotating solar-type stars by means of an axisymmetric mean field model that was previously applied to the Sun. This allows us to calculate the latitudinal entropy gradient with a reasonable physical basis. Our conclusions are as follows. (1) Differential rotation approaches the Taylor-Proudman state when stellar rotation is faster than solar rotation. (2) Entropy gradient generated by the attached subadiabatic layer beneath the convection zone becomes relatively small with a large stellar angular velocity. (3) Turbulent viscosity and turbulent angular momentum transport determine the spatial difference of angular velocity {Delta}{Omega}. (4) The results of our mean field model can explain observations of stellar differential rotation.

  11. Viscosity of Sheared Helical filament Suspensions

    NASA Astrophysics Data System (ADS)

    Sartucci, Matthew; Urbach, Jeff; Blair, Dan; Schwenger, Walter

    The viscosity of suspensions can be dramatically affected by high aspect ratio particles. Understanding these systems provides insight into key biological functions and can be manipulated for many technological applications. In this talk, the viscosity as a function of shear rate of suspensions of helical filaments is compared to that of suspensions of straight rod-like filaments. Our goal is to determine the impact of filament geometry on low volume fraction colloidal suspensions in order to identify strategies for altering viscosity with minimal volume fraction. In this research, the detached flagella of the bacteria Salmonella Typhimurium are used as a model system of helical filaments and compared to mutated straight flagella of the Salmonella. We compare rheological measurements of the suspension viscosity in response to shear flow and use a combination of the rheology and fluorescence microscopy to identify the microstructural changes responsible for the observed rheological response.

  12. Neoclassical Viscosities and Anomalous Flows in Stellarators

    NASA Astrophysics Data System (ADS)

    Ware, A. S.; Spong, D. A.; Breyfogle, M.; Marine, T.

    2009-05-01

    We present initial work to use neoclassical viscosities calculated with the PENTA code [1] in a transport model that includes Reynolds stress generation of flows [2]. The PENTA code uses a drift kinetic equation solver to calculate neoclassical viscosities and flows in general three-dimensional geometries over a range of collisionalities. The predicted neoclassical viscosities predicted by PENTA can be flux-surfaced average and applied in a 1-D transport model that includes anomalous flow generation. This combination of codes can be used to test the impact of stellarator geometry on anomalous flow generation. As a test case, we apply the code to modeling flows in the HSX stellarator. Due to variations in the neoclassical viscosities, HSX can have strong neoclassical flows in the core region. In turn, these neoclassical flows can provide a seed for anomalous flow generation. [1] D. A. Spong, Phys. Plasmas 12, 056114 (2005). [2] D. E. Newman, et al., Phys. Plasmas 5, 938 (1998).

  13. Hydrophilicity and the viscosity of interfacial water.

    PubMed

    Goertz, Matthew P; Houston, J E; Zhu, X-Y

    2007-05-08

    We measure the viscosity of nanometer-thick water films at the interface with an amorphous silica surface. We obtain viscosity values from three different measurements: friction force in a water meniscus formed between an oxide-terminated W tip and the silica surface under ambient conditions; similar measurements for these interfaces under water; and the repulsive "drainage" force as the two surfaces approach at various speeds in water. In all three cases, we obtain effective viscosities that are approximately 10(6) times greater than that of bulk water for nanometer-scale interfacial separations. This enhanced viscosity is not observed when we degrade the hydrophilicity of the surface by terminating it with -H or -CH3. In view of recent results from other interfaces, we conclude that the criterion for the formation of a viscous interphase is the degree of hydrophilicity of the interfacial pair.

  14. Quartz resonator fluid density and viscosity monitor

    DOEpatents

    Martin, Stephen J.; Wiczer, James J.; Cernosek, Richard W.; Frye, Gregory C.; Gebert, Charles T.; Casaus, Leonard; Mitchell, Mary A.

    1998-01-01

    A pair of thickness-shear mode resonators, one smooth and one with a textured surface, allows fluid density and viscosity to be independently resolved. A textured surface, either randomly rough or regularly patterned, leads to trapping of liquid at the device surface. The synchronous motion of this trapped liquid with the oscillating device surface allows the device to weigh the liquid; this leads to an additional response that depends on liquid density. This additional response enables a pair of devices, one smooth and one textured, to independently resolve liquid density and viscosity; the difference in responses determines the density while the smooth device determines the density-viscosity product, and thus, the pair determines both density and viscosity.

  15. Sludge based Bacillus thuringiensis biopesticides: viscosity impacts.

    PubMed

    Brar, S K; Verma, M; Tyagi, R D; Valéro, J R; Surampalli, R Y

    2005-08-01

    Viscosity studies were performed on raw, pre-treated (sterilised and thermal alkaline hydrolysed or both types of treatment) and Bacillus thuringiensis (Bt) fermented sludges at different solids concentration (10-40 g/L) for production of biopesticides. Correlations were established among rheological parameter (viscosity), solids (total and dissolved) concentration and entomotoxicity (Tx) of Bt fermented sludges. Exponential and power laws were preferentially followed by hydrolysed fermented compared to raw fermented sludge. Soluble chemical oxygen demand variation corroborated with increase in dissolved solids concentration on pre-treatments, contributing to changes in viscosity. Moreover, Tx was higher for hydrolysed fermented sludge in comparison to raw fermented sludge owing to increased availability of nutrients and lower viscosity that improved oxygen transfer. The shake flask results were reproducible in fermenter. This study will have major impact on selecting fermentation, harvesting and formulation techniques of Bt fermented sludges for biopesticide production.

  16. Hydrodynamic Electron Flow and Hall Viscosity

    NASA Astrophysics Data System (ADS)

    Scaffidi, Thomas; Nandi, Nabhanila; Schmidt, Burkhard; Mackenzie, Andrew P.; Moore, Joel E.

    2017-06-01

    In metallic samples of small enough size and sufficiently strong momentum-conserving scattering, the viscosity of the electron gas can become the dominant process governing transport. In this regime, momentum is a long-lived quantity whose evolution is described by an emergent hydrodynamical theory. Furthermore, breaking time-reversal symmetry leads to the appearance of an odd component to the viscosity called the Hall viscosity, which has attracted considerable attention recently due to its quantized nature in gapped systems but still eludes experimental confirmation. Based on microscopic calculations, we discuss how to measure the effects of both the even and odd components of the viscosity using hydrodynamic electronic transport in mesoscopic samples under applied magnetic fields.

  17. Second coefficient of viscosity in air

    NASA Technical Reports Server (NTRS)

    Ash, Robert L.; Zuckerwar, Allan J.; Zheng, Zhonquan

    1991-01-01

    Acoustic attenuation measurements in air were analyzed in order to estimate the second coefficient of viscosity. Data over a temperature range of 11 C to 50 C and at relative humidities between 6 percent and 91 percent were used. This analysis showed that the second coefficient of viscosity varied between 1900 and 20,000 times larger than the dynamic or first coefficient of viscosity over the temperature and humidity range of the data. In addition, the data showed that the molecular relaxation effects, which are responsible for the magnitude of the second coefficient of viscosity, place severe limits on the use of time-independent, thermodynamic equations of state. Compressible flows containing large streamwise velocity gradients, like shock waves, which cause significant changes in particle properties to occur during time intervals shorter than hundredths of seconds, must be modeled using dynamic equations of state. The dynamic model approach is described briefly.

  18. The direct viscosity enhancement of carbon dioxide

    SciTech Connect

    Iezzi, A.; Enick, R.; Brady, J. . Dept. of Chemistry)

    1988-01-01

    A high pressure viscometer has been constructed for use over a wide range of temperatures and pressures, including near-critical and supercritical conditions. An aluminum cylinder falls through a tube containing a stationary column of fluid, enabling viscosities to be determined from terminal velocity measurements. Preliminary results are presented on the search for an additive which can enhance the viscosity of carbon dioxide when present in low (less than 1%) concentrations.

  19. Eddy viscosity measurements in a rectangular jet

    NASA Technical Reports Server (NTRS)

    Swan, David H.; Morrison, Gerald L.

    1988-01-01

    The flow field of a rectangular jet with a 2:1 aspect ratio was studied at a Reynolds number of 100,000 (Mach number 0.09) using three-dimensional laser Doppler velocimetry (LDV). Velocity gradients, Reynolds stress tensor components, and scalar eddy viscosities are presented for the major and minor axis planes of the jet. The eddy viscosity model was found to be applicable only in the direction of maximum mean velocity gradient.

  20. Modified Chaplygin gas cosmology with bulk viscosity

    NASA Astrophysics Data System (ADS)

    Benaoum, H. B.

    2014-09-01

    In this paper, we investigate the viscous modified Chaplygin gas cosmological model. Solutions for different values of the viscosity parameter are obtained using both analytical and numerical methods. We have calculated the deceleration and defined newly statefinder {r, s} pair in D dimensions. It is shown that when D = 4, the usual statefinder parameters are recovered. Furthermore, we apply the statefinder diagnostic to the MCG model with and without viscosity in D dimensions and explore these parameters graphically.