Dimensional Probe Research Articles

Helicon waves in a converging-diverging magnetoplasma

Waves propagating along a converging-diverging rf magnetoplasma having the characteristics of a bounded m = 0 helicon mode are reported and characterised. The discharge features a 30cm separation between the region of radiofrequency energy deposition by a single loop antenna and the region of maximum magnetic field applied by a pair of coils. With 200W of rf input power, up to a five-fold increase in axial plasma density between the antenna and the magnetic mirror throat is observed together with an Ar II blue-mode. Two dimensional B-dot probe measurements show that the rf magnetic fields are closely guided by the converging-diverging geometry. The wave is characterised as a m = 0 mode satisfying the helicon dispersion relation on-axis with radial boundary conditions approximately matching the radii of the plasma column. Analysis of the wave phase velocity and wave axial damping failed to identify collisionless or collisional wave-plasma coupling mechanisms. Instead, the wave axial amplitude variations can be explained by local wave resonances and possible reflections from localised rapid changes of the refractive index. A Venturi-like effect owing to the funnel-shaped magnetoplasma and conservation of the wave energy may also explain some level of amplitude variations.

Effect of minor Sc additions on precipitation and mechanical properties of a new Al-Cu-Li alloy under T8 temper

The effects of minor Sc additions on the formation of various precipitates and mechanical properties of a new Al-Cu-Li alloy have been experimentally investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), three dimensional atomic probe (3DAP) analysis and tensile tests. Under T8 temper, the introduction of 0.092 wt% Sc accelerates the aging response of Al-Cu-Li alloy and induces a little reduction in the tensile and yield strength due to the decrease of solid solubility of Cu in Al alloy matrix and number density of T1 (Al2CuTi) strengthening phase, which are closely linked with the formation of insoluble Sc-containing W(AlCuSc) phase by consuming Cu solutes for the precipitation of T1 phase. Except for T1 and W phase, Nanoscale Al3(Sc,Zr) and S′ phases are also found after minor Sc addition. The 3DAP tomography indicates that the Al3(Sc,Zr) precipitates have a core-shell structure with Zr atoms mainly close to the shell and Sc atoms enriched in the core. It is believed that such precipitate is only probably composed of Al and Sc at the initial stage, and then Zr enters into them at the later stage, which hinders the diffusion of Sc in the matrix through the boundary into the interior of the particle and thus makes the coarsening rate of Al3Sc decrease.

Fetal speckle-tracking echocardiography: a comparison between two-dimensional and electronic spatio-temporal image correlation (e-STIC) technique

Background Speckle tracking technology has been applied to assess ventricular deformation throughout the cardiac cycle. An electronic four dimensional probe that allows rapid acquisition of electronic spatio-temporal image correlation volumes (eSTIC) has been recently introduced. Objectives The aim of our study was to investigate whether e-STIC acquisition improves deformation analyses reproducibility. Study design We recruited fetuses between 20 and 40 weeks of gestation. We obtained a 2D video clip and an e-STIC volume of a four-chamber view. We focused on left ventricular global strain (LV-GS) and left ventricular ejection fraction (LV-FE). Intraobserver, interobserver and intermethod agreement were assessed by means of intraclass correlation coefficient (ICC) and illustrated by Bland-Altman plots. Systematic differences between measurements were assessed using a paired t-test. Results The mean difference between LV-GS values obtained with e-STIC and 2D analysis was −0.10 (95% CI −2.28, 2.08). No systematic differences were found between the two techniques for LV-GS values (p-value = .927). The mean difference between LV-FE values obtained with e-STIC and 2D analysis was 7.55 (95% CI 4.16, 10.95; p-value <.001). The inter-rater reliability of LV-GS was moderate-to-substantial for both e-STIC and 2D. The inter-rater reliability of LV-FE obtained via e-STIC was superior to that obtained via 2D analysis. The intra-rater reliability of LV-GS obtained with e-STIC was superior to that obtained with 2D analysis (ICC 0.857; 95% IC 0.761–0.917). The intra-rater reliability of LV-FE obtained via e-STIC was superior to that obtained via 2D analysis (ICC 0.647; IC 0.51–0.783). Conclusions e-STIC seems to be a better technique than 2D analysis for intra-rater reliability of LV-GS. 4D acquisition might improve intrinsic limitations of speckle tracking echocardiography.

Quantum precision thermometry with weak measurements

As the minituarization of electronic devices, which are sensitive to temperature, grows apace, sensing of temperature with ever smaller probes is more important than ever. Genuinely quantum mechanical schemes of thermometry are thus expected to be crucial to future technological progress. We propose a new method to measure the temperature of a bath using the weak measurement scheme with a finite dimensional probe. The precision offered by the present scheme not only shows similar qualitative features as the usual Quantum Fisher Information based thermometric protocols, but also allows for flexibility over setting the optimal thermometric window through judicious choice of post selection measurements.

A CD probe with a tailored cantilever for 3D-AFM measurement

A critical dimensional (CD) probe, such as a boot shaped probe, is widely used for measuring the sidewall profiles of nanostructures in atomic force microscopy (AFM). However, conventional CD probes usually have high spring constants that restrict their ability to operate in critical dimension scanning modes. Furthermore, the flexure spring constant of the tip is much smaller than the torsion spring constant of the cantilever, which probably makes the sidewall measurement unstable. Here, we proposed a method of tailoring the probe where the cantilever was trimmed to reduce the spring constant. The simulation results, using a finite element method (FEM), illustrated that both the flexure and torsion spring constants decreased nearly ten times. Meanwhile, the torsional resonant frequency decreased to below 1 MHz, which could benefit the torsional oscillation scanning. By using a focused ion beam (FIB), a CD probe with a rectangular cantilever was reprocessed. It was mounted to a home-built three-dimensional AFM system (3D-AFM), and had the flexure and torsion sensitivities precisely calibrated. The ratio of the flexure sensitivity to torsion sensitivity showed good accordance with the simulation results. Additionally, a grating standard sample was measured using the tailored probe under a modified step-in scanning mode, and the error due to torsional deformation of the tip was compensated. The measurement results demonstrated the validity of the tailored CD probe in 3D metrology.

Approach to determine measurement uncertainty in complex nanosystems with multiparametric dependencies and multivariate output quantities

In many cases, the determination of the measurement uncertainty of complex nanosystems provides unexpected challenges. This is in particular true for complex systems with many degrees of freedom, i.e. nanosystems with multiparametric dependencies and multivariate output quantities. The aim of this paper is to address specific questions arising during the uncertainty calculation of such systems. This includes the division of the measurement system into subsystems and the distinction between systematic and statistical influences. We demonstrate that, even if the physical systems under investigation are very different, the corresponding uncertainty calculation can always be realized in a similar manner. This is exemplarily shown in detail for two experiments, namely magnetic nanosensors and ultrafast electro-optical sampling of complex time-domain signals. For these examples the approach for uncertainty calculation following the guide to the expression of uncertainty in measurement (GUM) is explained, in which correlations between multivariate output quantities are captured. To illustate the versatility of the proposed approach, its application to other experiments, namely nanometrological instruments for terahertz microscopy, dimensional scanning probe microscopy, and measurement of concentration of molecules using surface enhanced Raman scattering, is shortly discussed in the appendix. We believe that the proposed approach provides a simple but comprehensive orientation for uncertainty calculation in the discussed measurement scenarios and can also be applied to similar or related situations.

Novel physical probe configurations in a multi-probe based 3D MIMO OTA setup

In this paper, channel spatial characteristics which mainly depend on the spatial correlation are selected as the significant factors in over-the-air (OTA) testing for multiple input multiple output (MIMO) devices. The multi-probe anechoic chamber method, a promising candidate of the MIMO OTA testing methods, can reproduce the multipath environments in a controllable manner. A novel physical configuration based on the variation of relative positions of probes in a MIMO OTA setup is put forward to obtain better spatial characteristics. Two physical configurations are presented to make a comparison with the typical configuration in this paper. The simulation results show that by making a proper probe configuration, good channel simulation accuracy can be achieved. Meanwhile, in order to get better performance of emulating channel spatial characteristics, probes in the first and the last probe rings should be placed symmetrically in three dimensional (3D) physical probe configuration.

Sheathed probe thermal gas mass flow meter heat transfer analysis

The thermal gas mass flow meter is an important meter used in industrial measurement. When the environmental temperature changes, the measured gas physical parameters change correspondingly and the thermal gas mass flow meter output signal is affected, causing large measurement error. The influence of gas temperature on the sheathed probe measurements is analyzed in this paper based on experiments and heat transfer theory using a three dimensional probe and gas heat transfer mathematical model based on the heat conduction equation. The probe heat transfer process is analyzed under convection heat transfer coupling conditions. The experimental data were analyzed and compared against the theoretical results, with a maximum average relative error of only 4.56%. The rationality of the theoretical method is thus verified.

Plasma Uniformity Analysis of Inductively Coupled Plasma Assisted Magnetron Sputtering by a 2D Voltage Probe Array

A real-time monitoring of immersed antenna type inductively coupled plasma (ICP) was done with a homemade 2 dimensional voltage probe array to check the uniformity of the plasma. Measured voltage values with a high impedance voltmeter are close to the floating potential of the plasma. As the substrate carrier was moving into a magnetron sputtering plasma diffusive from a <TEX>$125mm{\times}625mm$</TEX> size cathode, measured results showed reliably separation of plasma into the upper and lower empty space over the carrier. Infra red thermal imaging camera was used to observe the cross corner effect in situ without eroding a target to the end of the usage. 3 dimensional particle trace model was used to analyze the magnetron discharge's behavior.

The spin of holographic electrons at nonzero density and temperature

We study the Green's function of a gauge invariant fermionic operator in a strongly coupled field theory at nonzero temperature and density using a dual gravity description. The gravity model contains a charged black hole in four dimensional anti-de Sitter space and probe charged fermions. In particular, we consider the effects of the spin of these probe fermions on the properties of the Green's function. There exists a spin-orbit coupling between the spin of an electron and the electric field of a Reissner-Nordstrom black hole. On the field theory side, this coupling leads to a Rashba like dispersion relation. We also study the effects of spin on the damping term in the dispersion relation by considering how the spin affects the placement of the fermionic quasinormal modes in the complex frequency plane in a WKB limit. An appendix contains some exact solutions of the Dirac equation in terms of Heun polynomials.

Two-dimensional micron-step probe drive for laboratory plasma measurement

Laboratory measurement of small-scale ( approximately 1 mm) magnetic phenomena over an extended area is a challenge requiring precise diagnostics. We present a novel two dimensional magnetic probe platform capable of directly measuring the magnetic field over a 36 cm(2) region at spatial resolutions better than 1 mm. The platform is discussed in the context of an experiment at the Large Plasma Device facility at UCLA, designed to measure the magnetic interaction between two counterpropagating laser-produced plasmas. The use of a precise, repeatable positioning platform enables the recovery of information about the interaction using cross-correlation techniques.

Study of three dimensional zonal flows characteristic and novel probe design in HL-2A

Three dimensional(3-D) features of geodesic acoustic mode zonal flows (GAMZF) were first determined with novel three-step zonal flow probes (TSZFP) at the edge of the HL-2A Tokamak plasmas. Three arrays of TSZFP were located 65mm and 800mm apart. The poloidal mode (m～0) and toroidal mode (n～0) of electric potential and field perturbations were simultaneously determined for the first time. Corresponding frequencies were estimated as 7kHz，which are in good agreement with theoretical prediction. The radial scale lengths of ZF were 24—42cm. The formation mechanism of the flows is identified to be nonlinear three wave coupling between high frequency turbulent fluctuations and the flows. The regulating effect of the flows on the ambient turbulent fluctuations was also demonstrated. The Reynolds stress driven by edge fluctuation is one of the main reasons driving the poloidal flow. It is also verified that the radial gradient of Reynolds stress can drive zonal flows.

Comparative Study of Flat and Round Collectors Using a Validated 1D Fluid Probe Model

AbstractIn the literature two different types of Gundestrup‐like probe designs are proposed: design with flat and with round collectors. In this paper we study the influence of different collector shapes of Gundestrup‐like probes on the accuracy of the measurement of the parallel and perpendicular flows. A one dimensional fluid probe model is used for deducing both Mach numbers of the unperturbed flow from the probe data. An analytical expression relates the plasma flow to the measured ion saturation currents collected at the upstream and downstream collecting surfaces of the probe. For flat collectors, the analytical model is validated by comparing it to a two dimensional quasi‐neutral Particle In Cell (PIC) simulation code. An extension of the theoretical model then allows us to study round collectors. We performed an accuracy study which showed that systematic errors are introduced when round collectors are employed for determination of the perpendicular flow which is systematically overestimated. The error can reach more than 70% when the perpendicular flow increases and when the angle of the collecting surface with respect to the magnetic field (θ → 0)is small. The correct analytical expression is applied to experimental data from Gundestrup probe measurements with round collectors on the CASTOR tokamak. The analysis shows that for these measurements the error introduced by using the expression for flat collectors remains negligible, supporting our former use of the model for flat collectors. A new advanced Gundestrup‐like probe design and the motivation for the choice of flat collectors are presented. (© 2006 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Examination of the flow rheological and textural properties of polymer gels composed of poly(methylvinylether‐co‐maleic anhydride) and poly(vinylpyrrolidone): Rheological and mathematical interpretation of textural parameters

The purpose of this study was to mathematically characterize the effects of defined experimental parameters (probe speed and the ratio of the probe diameter to the diameter of sample container) on the textural/mechanical properties of model gel systems. In addition, this study examined the applicability of dimensional analysis for the rheological interpretation of textural data in terms of shear stress and rate of shear. Aqueous gels (pH 7) were prepared containing 15% w/w poly(methylvinylether‐co‐maleic anhydride) and poly(vinylpyrrolidone) (PVP) (0, 3, 6, or 9% w/w). Texture profile analysis (TPA) was performed using a Stable Micro Systems texture analyzer (model TA‐XT 2; Surrey, UK) in which an analytical probe was twice compressed into each formulation to a defined depth (15 mm) and at defined rates (1, 3, 5, 8, and 10 mm s−1), allowing a delay period (15 s) between the end of the first and beginning of the second compressions. Flow rheograms were performed using a Carri‐Med CSL2‐100 rheometer (TA Instruments, Surrey, UK) with parallel plate geometry under controlled shearing stresses at 20.0° ± 0.1°C. All formulations exhibited pseudoplastic flow with no thixotropy. Increasing concentrations of PVP significantly increased formulation hardness, compressibility, adhesiveness, and consistency. Increased hardness, compressibility, and consistency were ascribed to enhanced polymeric entanglements, thereby increasing the resistance to deformation. Increasing probe speed increased formulation hardness in a linear manner, because of the effects of probe speed on probe displacement and surface area. The relationship between formulation hardness and probe displacement was linear and was dependent on probe speed. Furthermore, the proportionality constant (gel strength) increased as a function of PVP concentration. The relationship between formulation hardness and diameter ratio was biphasic and was statistically defined by two linear relationships relating to diameter ratios from 0 to 0.4 and from 0.4 to 0.563. The dramatically increased hardness, associated with diameter ratios in excess of 0.4, was accredited to boundary effects, that is, the effect of the container wall on product flow. Using dimensional analysis, the hardness and probe displacement in TPA were mathematically transformed into corresponding rheological parameters, namely shearing stress and rate of shear, thereby allowing the application of the power law (η = kγn) to textural data. Importantly, the consistencies (k) of the formulations, calculated using transformed textural data, were statistically similar to those obtained using flow rheometry. In conclusion, this study has, firstly, characterized the relationships between textural data and two key instrumental parameters in TPA and, secondly, described a method by which rheological information may be derived using this technique. This will enable a greater application of TPA for the rheological characterization of pharmaceutical gels and, in addition, will enable efficient interpretation of textural data under different experimental parameters. © 2002 Wiley‐Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:2090–2101, 2002

Experimental studies of magnetic reconnection

Laboratory magnetic reconnection experiments have been performed for nearly 20 years. Elegant experiments by Stenzel and Gekelman [R. L. Stenzel and W. Gekelman, Phys. Rev. Lett. 42, 1055 (1979); W. Gekelman and R. L. Stenzel, Phys. Rev. Lett. 54, 2414 (1985)] focused on the measurement of field quantities with a single movable probe in a highly reproducible plasma. Observations included a very thin current sheet (on the order of c/ωpe), accelerated electrons, and whistler waves. The argon ions were unmagnetized in these experiments. Recent magnetohydrodynamic (MHD) experiments by Yamada and Ono have used merging plasmoids [M. Yamada, Y. Ono, A. Hayakawa, M. Katsurai, and F. W. Perkins, Phys. Rev. Lett. 65, 721 (1990); Y. Ono, M. Yamada, T. Akao, T. Tajima, and R. Matsumoto, Phys. Rev. Lett. 76, 3328 (1996)] and have measured three dimensional effects and ion acceleration. We have observed correlations between magnetic reconnection and energetic ion flow events with merging force free spheromaks at the Swarthmore Spheromak Experiment (SSX) [T. W. Kornack, P. K. Sollins, and M. R. Brown, Phys. Rev. E 58, R36 (1998)]. The reconnection layer is measured with linear and two dimensional probe arrays and ion flow is directly measured with a retarding grid energy analyzer. Flow has been measured both in the plane of the reconnection layer and out of the plane. The outflow velocity is nearly Alfvénic in the reconnection plane and the scale of the magnetic structures is consistent with collisionless reconnection theories (on the order of c/ωpi). Results from the two dimensional array show the formation of magnetic islands correlated with super-Alfvénic ions accelerated normal to the layer.

Monte carlo simulation of the EBIC grain boundary contrast in semiconductors

The electron beam induced current (EBIC) recombination contrast of grain boundaries (GB) is calculated by means of a Monte Carlo simulation algorithm. After considering a pointlike generation source, a three-dimensional distribution of pointlike sources is simulated and used to calculate the EBIC profiles across the grain boundary. In both cases, we observe a saturation of the maximum EBIC contrast as the carrier lifetime within the GB decreases. The results show, for a three dimensional electron probe, a linear dependence of the contrast on the GB width. In addition, extrapolated values of the maximum contrast obtained for a zero width GB are in good agreement with that calculated by analytical models.

試料表面測定のためのＳＴＭ用三次元探査微動装置の作成

We fabricated the three dimensional slight probe movement system for scanning tunneling microscope (STM), The scanner used the piezoelectric tube, We measured the hysterical expansion for the piezo tube and a convection value of the control system for scanner.

GALAXY COLOR AND LARGE SCALE STRUCTURE

ABSTRACT More than a decade of galaxy surveys have produced a unified picture in which luminous matter is distributed in clusters and superclusters of galaxies connected by filamentary structures and surrounding large voids. Many studies have also provided considerable evidence that the properties of galaxies depend on their environment. However, disagreement remains over whether the environmental differences arise from conditions at the time when the galaxies formed or from their subsequent evolution. Part of the confusion is due to the effect of galaxy clusters, since they contain a wide range of galaxy densities and could be responsible for the observed environmental dependencies even at low density. In this thesis we examined the dependence of the large scale distribution of galaxies on galaxy color. We carried out a medium deep (bJ <~ 20) multi-pencil-beam redshift survey at the North Galactic Pole in nine 40 arcminute fields spanning a 5 degrees X 5 degrees area. This survey was conducted initially to check the discovery by Broadhurst et. al. (Nature, 343, 726, 1990) of strong and apparently periodic structure, and showed that peaks detected in their Northern survey appear to be due to transverse structures rather than due to galaxy clusters. Our final catalog contains 307 galaxies with redshifts and colors, to which we added 46 galaxies from an existing survey. By treating the pencil-beams as a one dimensional probe along the line of sight we determine the extent to which the galaxies in these structures are segregated by color. We used the statistical technique of measuring moments of counts in cells to study how the fluctuations of galaxy counts changed with scale. We first divided the galaxy sample into red and blue halves and found that the fluctuations in the red galaxy distribution were stronger than those of the blue on all scales out to 60 h-150 Mpc. This result suggests that the structures are dominated by the red galaxies. We checked that this effect was not caused entirely by the two largest structures in our survey by removing them from the sample and repeating the moment calculations. We also examined whether the difference in the galaxy distributions represented a continuous trend with color or were merely due to the clustering of the reddest galaxies. After dividing the sample into three color subgroups and comparing their moments, we found that the moments of the yellow galaxies are indeed intermediate between those of the red and blue galaxies. Finally, we tested the extent to which the difference between the red and blue galaxy distributions was due to small-scale clustering. We measured a modified second moment from which we remove the contribution of galaxy pairs contained within a single beam, thereby eliminating the effect of small-scale correlations. We found that, while there remained a difference between the red and blue galaxy distributions, its significance was substantially decreased, which suggests that the dominant contribution to the color segregation is small-scale clustering within the transverse structures. Overall, our results imply that color segregation of galaxies occurs primarily on scales over which they can be explained by environmentally dependent evolutionary processes, such as galaxy-galaxy and galaxy-IGM interactions, rather than the conditions under which the galaxies formed.

Performance evaluation of a three dimensional intensity probe.

A three dimensional intensity probe using four microphones is proposed. Four microphones are placed at apexes of a regular tetrahedron. One is placed in the front and three others consisting a vertical regular triangle are in the back. The microphones are attached at the tips of parallel thin tubes. The microphone arrangement is not the conventional face to face type. The aim of this type of microphone arrangement is to design a sound intensity probe with a simple structure, which is essential for reducing the diffraction problem. Algorithms for three dimensional intensity components from cross spectra are given as well as for leakage components. Measurements of sensitivity characteristics in an anechoic room using two types of probes with 60mm and 20mm microphone separations show that sensitivity fluctuations are small enough (less than 1dB) for the practical application of the sound intensity method. The leakage errors of approximately 5%(-13dB) seem also acceptable. The measurement results indicate that sensitivity and leakage errors will become smaller if a more ideal plane wave field in an anechoic room is achieved.

PHiDAS: A two dimensional Langmuir probe array and high capacity CAMAC based data acquisition system

An 8×8 array of Langmuir probes has been developed for measuring turbulent plasma parameters in tokamak edge plasmas. Fluctuations in plasma density ñ(r,θ,t) and floating potential φ̃f(r,θ,t) can be measured by the diagnostic, as well as the steady state (dc), profiles in n̄e(r,θ) and φ̄f(r,θ). The signal from each probe is processed by individual custom pre-amplifier circuits and the data from all probes are acquired simultaneously by a custom CAMAC based data acquisition system. This data acquisition system has 10 bit resolution with a maximum speed of 20 MS/s and has applications for various types of tokamak diagnostic arrays. Design considerations for the probe array and data acquisition system are discussed. Preliminary results from the probe array will be presented.