|
|
|
Calculations of slurry pump jet impingement loads
This paper presents a methodology to calculate the impingement load in the region of a submerged turbulent jet where a potential core exits and the jet is not fully developed. The profile of the jet flow velocities is represented by a piece-wise linear function which satisfies the conservation of momentum flux of the jet flow. The adequacy of the of the predicted jet expansion is further verified by considering the continuity of the jet flow from the region of potential core to the fully developed region. The jet impingement load can be calculated either as a direct impingement force or a drag force using the jet velocity field determined by the methodology presented.
Calculations of slurry pump jet impingement loads
1996-03-04
This paper presents a methodology to calculate the impingement load in the region of a submerged turbulent jet where a potential core exits and the jet is not fully developed. The profile of the jet flow velocities is represented by a piece-wise linear function which satisfies the conservation of momentum flux of the jet flow. The adequacy of the of the predicted jet expansion is further verified by considering the continuity of the jet flow from the region of potential core to the fully developed region. The jet impingement load can be calculated either as a direct impingement force or a drag force using the jet velocity field determined by the methodology presented.
Single And Multiple Jet Penetration Experiments Into Geologic Materials
This paper presents the results of experiments that investigate the effect of single and multiple jet penetration into geologic materials. In previous studies of jet penetration into concrete targets, we demonstrated that an enhanced surface crater could be created by the simultaneous penetration of multiple shaped charge jets and that an enhanced target borehole could be created by the subsequent delayed penetration of a single shaped charge jet. This paper describes an extension of the multiple jet penetration research to limestone and granite.
Single And Multiple Jet Penetration Experiments Into Geologic Materials
This paper presents the results of experiments that investigate the effect of single and multiple jet penetration into geologic materials. In previous studies of jet penetration into concrete targets, we demonstrated that an enhanced surface crater could be created by the simultaneous penetration of multiple shaped charge jets and that an enhanced target borehole could be created by the subsequent delayed penetration of a single shaped charge jet. This paper describes an extension of the multiple jet penetration research to limestone and granite.
Single And Multiple Jet Penetration Experiments Into Geologic Materials
2003-12-19
This paper presents the results of experiments that investigate the effect of single and multiple jet penetration into geologic materials. In previous studies of jet penetration into concrete targets, we demonstrated that an enhanced surface crater could be created by the simultaneous penetration of multiple shaped charge jets and that an enhanced target borehole could be created by the subsequent delayed penetration of a single shaped charge jet. This paper describes an extension of the multiple jet penetration research to limestone and granite.
Hydrodynamical Simulations of the Jet in the Symbiotic Star MWC 560
In Papers I and II in this series, we presented hydrodynamical simulations of jet models with parameters representative of the symbiotic system MWC 560. These were simulations of a pulsed, initially underdense jet in ...
The characteristics of annular jet pump for the transportation of solid materials
1998-11-01
Annular jet pump can be used for the transportation of solid materials and fish. The effect of annular type nozzle shapes and the effect of the entrance types of the primary fluid on the characteristics of annular jet pump is sought in this paper. Experiments were done for several jet fluid flow rates. Water was used for both the primary fluid and secondary fluid. The efficiency curves for the annular jet pump for 90 deg. primary fluid entrance to the high pressure chamber are presented in this paper. The efficiency curves for the annular jet pump for different types of primary fluid entrance to the high pressure chamber are also presented in this paper, showing the annular jet pump which has 45 deg. double entrance type is the most effective among the tested ones. (author). 6 refs., 10 figs., 3 ills.
A desktop electrohydrodynamic jet printing system
2010-01-01
This paper discusses the design and integration of a desktop system for electrohydrodynamic jet (E-jet) printing. E-jet printing is a micro/nano-manufacturing process that uses an electric field to induce fluid jet printing through micro/nano-scale nozzles. This enables better control and resolution than traditional jet-printing processes. The printing process is predominantly controlled by changing the voltage potential between the nozzle and the substrate. The push to drive E-jet printing towards a viable micro/nano-manufacturing process has led to the design of a compact, cost effective, and user friendly desktop E-jet printing system. The hardware and software components of the desktop system are described in the paper. Experimental results are presented to validate the performance of ...
A flexible cold microplasma jet using biocompatible dielectric tubes for cancer therapy
2010-01-01
This paper describes a flexible microplasma jet device using a Tygon S-54-HL tube as a biocompatible tube and its potential in developing cancer therapies. The optical and physical properties of the plasma jets and preliminary apoptosis data of cultured murine tumor cells and nontumor fibroblast cells treated with these plasma jets are presented. Microplasma jets were observed to induce apoptosis in cultured murine cells in a dose-dependent manner. The murine melanoma tumor cells were more sensitive to plasma treatment than fibroblast cells. These features allow the direct and precise application of this microplasma jet device to tumor cells
Plasma jet properties in a new spraying process at low pressure for large area thin film deposition
2001-02-01
This paper describes an experimental investigation of plasma jet properties of a DC torch operated at low pressure (below 10 mbar). A modified enthalpy probe system is described, which allows gas sampling from the plasma jet at pressures down to the mbar range. Measurements of the specific enthalpy, temperature and velocity throughout the jet for different pressures are presented and discussed. In the pressure range investigated, the jet flow is supersonic and compressible theory is used to infer the velocity from the dynamic pressure measured at the probe tip. In addition, optical emission spectroscopy of the plasma jet is used to evidence the differences of these low-pressure plasmas with respect to common, atmospheric pressure thermal jets. These preliminary measurements are the starting points towards a better understanding of plasma jets at low operating pressures in view of new process development and optimisation. (authors)
Enhancement of synthetic jets by means of an integrated valve-less pump
2005-01-01
The paper studies the performance of the new fluid jet actuator based on the novel principle of the generation of fluid jet, which has been presented in [Z. Travnicek, A.I. Fedorchenko, A.-B. Wang, Enhancement of synthetic jets by means of an integrated valve-less fluid pump. Part I. Design of the actuator, Sens. Actuators A, 120 (2005) 232-240]. The fluid jet actuator consists of a synthetic jet actuator and a valve-less pump. The resulting periodical fluid jet is intrinsically non-zero-net-mass-flux, in contrast to the traditional synthetic jet. The numerical results have been compared with the laboratory experiments comprising phase-locked smoke visualization and time-mean velocity measurements. The results have confirmed the satisfactory performance of the actuator.
A Thomson scattering diagnostic to measure fast ion and alpha-particle distributions in JET
1988-01-01
The paper presents the findings of a feasibility investigation into the proposed Thomson scattering diagnostic to measure fast ion and alpha-particle distributions in JET. A description is given of the motivation for alpha particle diagnostics on JET, followed by a brief survey of possible alpha-particle diagnostics for JET. The basic principles of the collective Thomson scattering technique are presented, along with its implementation on JET. The expected performance of the system, and other applications of the diagnostic system are also discussed. (U.K.)
Tilted Micro Air Jet for Flow Control
2009-12-15
In this paper, we present an interesting method to microfabricate a tilted micro air jet generator. We used the well-know deep reactive ion etching (DRIE) technique in order to realize in a silicon substrate a double side etching. For aircraft and cars, micro air jets will take an important place for fluid control. Micro air jets are characterized by their speed, frequency and tilt. Usually, this micro air jets are produced by fluidic microsystems. We presented experimental results about micro tilted air jets. A comparison between finite element method simulation, theory and experimental results are performed to define the microsystem geometry leading a specific air jet angle.
Erosion, Contamination, and Migration
2010-01-01
This paper will summarize studies of carbon impurity sources, contamination, and migration developed through JET methane gas injection experiments. These studies were analyzed using the 2D SOL code EDGE2D/NIMBUS. The code is capable of repeating the JET analysis using the ITER geometry and SOL plasma. This allows assessment of whether the physical processes occurring in JET might also occur in ITER, and thus whether the JET results transfer, in any sense, to the ITER plasmas. Certainly, the ITER choice of wall materials (W and Be) is different than for the present JET C studies. So the present status of these studies is to relate JET carbon behavior to carbon in ITER.JET carbon sources were studied spectroscopically and analyzed with atomic physics models in EDGE2D. The carbon sources are dominated by chemical sputtering at rates which are within a factor-of-two of the published ...
The 90 deg Acoustic Spectrum of a High Speed Air Jet
Tam and Auriault successfully predicted the acoustic spectrum at 90deg to the axis of a high speed air jet by using an acoustic equation derived from ad hoc kinetic theory-type arguments. The present paper shows that ...
Landing on the Moon Cratering from a Jet
2009-10-20
This paper describes work done in investigating cratering processes by impinging jets. It accompanies a video made for the fluid dynamics video presentations at the Division of Fluid Dynamics meeting, November 22-24, 2009.
Computing Axisymmetric Jet Screech Tones using Unstructured Grids
The purpose of this paper is to show that computations with an aeroacoustic feedback loop, the jet screech noise, can be obtained using truly unstructured grid technology. Numerical results are presented for a nozzle with ...
2009-01-01
A novel noncontact indentation system with the combination of an air jet and optical coherence tomography (OCT) was presented in this paper for the quantitative measurement of the mechanical...Full Text Available
Experimental studies of stability and beta limit in JET
2008-01-01
The paper presents results on the use of resonant field amplification for experimental probing of stability and beta-limits (beta is the ratio of the plasma pressure to the magnetic field pressure) in JET. It is found that an externally applied helical magnetic field is strongly enhanced when the plasma exceeds the ideal no-wall stability limit or approaches proximity to other marginally stable (i.e. current-driven) modes. This effect is known as the resonant field amplification (RFA) and was used for the systematic probing of stability in different advanced regimes on JET. The application of this technique on JET is discussed in the paper and the results of the RFA measurements are presented and related to the observed limitations in beta
2001-10-01
The LPPS processes, which use DG plasma jets expanding at low pressure, are widely used for the deposition of various kinds of layers. The supersonic expansion of the plasma jet in a low-pressure environment requires special care in the operating conditions in order to obtain the desired properties of the flow, regarding powder injection and transport and plasma jet-surface interaction. This paper presents measurements of the plasma jet properties for different chamber pressures. The torch is operated both in the over-expanded and under-expanded regimes, according to pressure measurements at the exit of the nozzle as a function of the backpressure. The topology of the expansion-compression zones of the plasma jet for the different operating pressures is inferred from imaging of the plasma jet. In addition, a modified enthalpy probe system is used to measure the specific enthalpy and the stagnation pressure profiles throughout the jet. De- termination of the local free-stream jet parameters, such as the temperature and velocity, for the case of supersonic flow is made assuming an isentropic frozen stagnation process at the probe tip. For these calculations the pressure dependence of the equilibrium thermodynamic and transport properties is accounted for. Discussion on expanded jet rarefaction is made for chamber pressure below 20 mbar, in the light of plasma jet imaging and nozzle exit pres- sure measurements. (author)
Experimental investigation of side jet interaction with a supersonic cross flow
2008-01-01
The following paper reports on experimental investigations on high-speed missile control. The paper looks especially at the interference effects of side jets with supersonic cross flow. Detailed wall pressure measurements are presented for three different jet configurations. The shock structure is shown with Schlieren images and the wall streamlines are visualised with oil flow technique.
Computational modeling of a utility boiler tangentially-fired furnace retrofitted with swirl burners
2010-01-01
The paper presents 3D numerical investigation of OP-380 boiler tangentially-fired furnace utilizing bituminous coal. The boiler was retrofitted by replacing traditional jet burners with RI-JET2 (Rapid Ignition - JET) swirl burners. This kind of solution is unique in power generation systems. The purpose of this work is to show how the flow, combustion performance and heat exchange in the furnace are affected by introducing rapid ignition phenomena in RI-JET2 burners instead of delayed ignition associated with the traditional jet burners. Results were compared to simulations of similarly designed boiler equipped with traditional jet burners. Furnace simulation was preceded with a single RI-JET2 burner simulation at the inlet to a virtual combustion chamber. The results have shown that pulve...
Proceedings of the Third Spaceborne Imaging Radar Symposium
This publication contains summaries of the papers presented at the Third Spaceborne Imaging Radar Symposium held at the Jet Propulsion Laboratory (JPL), California Institute of Technology, in Pasadena, ...
A study on supersonic coherent jet characteristics using computational fluid dymanics
2009-01-01
Supersonic gas jets are widely used in BOF and EAF steelmaking for refining the liquid iron inside the furnace. Supersonic gas jets are preferred over subsonic jets because of high dynamic pressure associated with it which results in higher depth of penetration and better mixing. Laval nozzles are used to accelerate the gas jets to supersonic velocities of around 2.0 Mach number in steelmaking. When a supersonic gas jet exits from a Laval nozzle, it interacts with surrounding environment to produce a region of turbulent mixing. This process results in an increase in jet diameter and decrease in jet velocity with increasing distance from nozzle exit. During oxygen blowing, the higher the distance between liquid surface and the nozzle exit the more is the entrainment of surrounding fluid which in turn decreases the impact velocity as well as momentum transfer to the liquid. Hence, it is desirable to locate the nozzle close to the liquid metal surface. But the disadvantage of this is the sticking of slag/metal droplets on the lance tip which results in poor tip life. In order to solve the problem, coherent jet technology has been introduced in the EAF steelmaking process at the end of last century. The potential core length (the length up to which the axial jet velocity is equal to the exit velocity at the nozzle) of a coherent supersonic jet is about 40 nozzle diameters compared to 10 nozzle diameters in case of normal supersonic jet. Coherent gas jets are produced by surrounding the normal supersonic jet with flame envelope [1]. The flame envelope is created using a fuel and oxidant. Due to the flame, the entrainment of the surrounding gas into the supersonic jet is reduced, leading to a higher potential core length of the supersonic jet. Although the steelmaking industries have been using the coherent supersonic jet for last one decade, not much research work has been done to investigate the physics involved in supersonic coherent jet. In this study, Computational fluid dynamics (CFD) simulations of supersonic jet with and without shrouding flame were carried out and validated against experimental data [2]. The numerical results showed that the potential core length of the coherent supersonic jet is 4 times longer than that of a supersonic jet without flame shrouding which were in good agreement with experimental results. The CFD model results were then used to analyse the flame shrouding effect on the central supersonic jet. Publisher: Faculty of Engineering and Industrial Sciences, Swinburne University of Technology Contributor: Swinburne University of Technology. Faculty of Engineering and Industrial Sciences Other identifier: swin:15977 Language: English Source: Paper presented at the High Temperature Processing Symposium 2010, Swinburne University of Technology, Melbourne, Australia, 08-09 February 2010, pp. 29-30; Rights: Copyright © 2009 Swinburne University of Technology.
On the universality of hadronisation corrections to QCD jets
2009-01-01
We improve previously derived analytical estimates of hadronisation corrections to QCD jets at hadron colliders, firmly establishing at the two-loop level the link to the well-known power corrections to LEP event-shape variables. The results of this paper apply to jets defined in the kt and anti-kt algorithms but the general framework presented here holds also for other algorithms for which calculations are in progress
Modelling with COREDIV code of JET ILW configuration
2010-01-01
In this paper we present integrated numerical modeling for the first time applied to AT discharges with tungsten wall using the COREDIV code. We concentrate on numerical simulations of Ne seeded scenarios in the new ILW JET configuration. Results show that the JET operating space might be limited, with tungsten wall, to high density plasmas (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
A feasibility study of steam-jet refrigeration
1998-12-01
In this paper a feasibility study of steam-jet refrigeration is conducted. First and second law analyses as well as the economics of a steam-jet refrigeration system are presented. Thermodynamic parameters investigated include the coefficient of performance (COP), refrigerating effect, condenser heat rejection, motive steam requirements, second law efficiency, and system irreversibility. Economic parameters investigated include equipment costs, space needs, power requirements, and installed and operation costs. (Author)
Observational features of equatorial coronal hole jets
2010-02-11
Collimated ejections of plasma called "coronal hole jets" are commonly observed in polar coronal holes. However, such coronal jets are not only a specific features of polar coronal holes but they can also be found in coronal holes appearing at lower heliographic latitudes. In this paper we present some observations of "equatorial coronal hole jets" made up with data provided by the STEREO/SECCHI instruments during a period comprising March 2007 and December 2007. The jet events are selected by requiring at least some visibility in both COR1 and EUVI instruments. We report 15 jet events, and we discuss their main features. For one event, the uplift velocity has been determined as about 200 km/s, while the deceleration rate appears to be about 0.11 km/s2, less than solar gravity. The average jet visibility time is about 30 minutes, consistent with jet observed in polar regions. On the basis of the present dataset, we provisionally conclude that there are not substantial physical differences between polar and equatorial coronal hole jets.
Instability of a supersonic shock free elliptic jet
1990-01-01
This paper presents a comparison of the measured and the computed spatial stability properties of an aspect ratio 2 supersonic shock free elliptic jet. The shock free nature of the elliptic jet provides an ideal test of validity of modeling the large scale coherent structures in the initial mixing region of noncircular supersonic jets with linear hydrodynamic stability theory. Both aerodynamic and acoustic data were measured. The data are used to compute the mean velocity profiles and to provide a description of the spatial composition of pressure waves in the elliptic jet. A hybrid numerical scheme is applied to solve the Rayleigh problem governing the inviscid linear spatial stability of the jet. The measured mean velocity profiles are used to provide a qualitative model for the cross sectional geometry and the smooth velocity profiles used in the stability analysis. Computational results are presented for several modes of instability at two jet cross sections. The acoustic measurements show that a varicose instability is the jet's perferred mode of motion. The stability analysis predicts that the Strouhal number varies linearly as a function of axial distance in the jet's initial mixing region, which is in good qualitative agreement with previous measurements. 18 refs., 18 figs., 1 tab.
Interview with Mike Campbell, HR Director of easyJet: Interview by Rachel Brown
2008-01-01
Purpose - This paper aims to present the views of Mike Campbell HR Director at easyJet. Design/methodology/approach - This paper provides an interview with Mike Campbell who has a wealth of experience in development and personnel roles across Europe, Asia, Africa and the Middle East. Findings - The paper finds new insights into the methods of people management at easyJet. Originality/value - The paper provides an insightful interview with Mike Campbell.
2007-01-01
The origin of zonal jets on the jovian planets has long been a topic of scientific debate. In this paper we show that deep convection in a spherical shell can generate zonal flow comparable to that observed on Jupiter and Saturn, including a broad prograde equatorial jet and multiple alternating jets at higher latitudes. We present fully turbulent, 3D spherical numerical simulations of rapidly rotating convection with different spherical shell geometries. The resulting global flow fields tend to be segregated into three regions (north, equatorial, and south), bounded by the tangent cylinder that circumscribes the inner boundary equator. In all of our simulations a strong prograde equatorial jet forms outside the tangent cylinder, whereas multiple jets form in the northern and southern hemi...
Operational limits for the ITER-like wall in JET
2009-01-01
The ITER-like wall project in JET aims at an optimal use of the unique features of JET, such as beryllium and tritium compatibility, to explore operation within the limits of the ITER wall materials. A full replacement of the presently carbon-based first wall will result in the surfaces facing the plasma being mainly beryllium in the main chamber and tungsten in the divertor. At the same time, the JET auxiliary heating power will be upgraded allowing access to ITER-relevant energy loss densities in disruptions and edge localized modes. In this way, the JET wall will go from being almost indestructible, to making the material-driven operational constraints predicted for ITER a more immediate reality for JET. This paper describes the methodology being used to define and apply these limits while optimizing experimental flexibility
2009-01-01
The given paper presents the modeling results of the bending melt jet perturbations in a coolant pool and disintegration of the jets on drops. It was shown that among the problems requiring studies for the improvement of the passive protection systems against severe accidents at NPP there are disintegration of the thin jets due to bending instability and the jet penetration length into volatile coolant pool. These problems belong to the initial stage of the severe accident in containment by the corium melt jet spreading under reactor vessel water pool. Successful solution of these problems predetermines the effectiveness of the passive protection system against severe accidents at NPP
Investigation of low-level-jets over rural and urban areas using two sodars
2008-01-01
This paper is devoted to the experimental study of jet streams at heights up to 400 m agl (the so called Low-Level Jet, or LLJ) with the help of sodars. These LLJs, which are not connected either to catabatic winds or to synoptic front passing, but are regularly observed in the mid-latitudes over a flat terrain under nocturnal inversion conditions, are investigated. Preliminary results of simultaneous investigations of LLJs over the center of the Moscow megalopolis and over a nearby rural area are presented. Continuous sodar data on wind speed profiles collected during 27 days in July 2005 were analyzed together with in situ data from a meteorological mast. Empirical distributions of the maximum jet speed and the height of jet axis were obtained. The relationships between the LLJ parameters and some characteristics of the surface layer were found. Over the urban area, the jets ...
Implementation and Performance of the ATLAS Jet Trigger
ATLAS is one of the main experiments at the LHC. Its trigger system has been designed to be flexible in order to cover a wide range of physics topics, while reducing the rate from the nominal 40 MHz to about 200 Hz. In order to achieve this, the ATLAS trigger system searches for high pT objects, like leptons, jets, photons, or missing transverse energy. The jet trigger starts at the first level trigger with dedicated processors that search for high ET hadronic energy depositions. At the second level trigger, the jet signatures are verified with the execution of a dedicated, fast cone reconstruction algorithm followed by a simple calibration scheme. In the third level trigger any of the offline jet reconstruction algorithms can be used. In this paper we will present the challenges of the jet trigger, describing the implementation and the expected performance.
A turbulent model for the surface brightness of extragalactic jets
2009-03-09
This paper summarizes the known physics of turbulent jets observed in laboratory experiments. The formula, which gives the power released in turbulence describes the concentration of turbulence/relativistic particles in each point of the astrophysical jets. The same expression is also used to analyze the power released in turbulence in the case of pipe and non Newtonian fluids. Through an integral operation it is possible to deduce the intensity of synchrotron radiation for a profile perpendicular or not to a straight jet, a 2D map for a perpendicular, randomly oriented straight jet as well as a 2D map of complex trajectories such as NCC4061 and 3C31. Presented here is a simulation of the spectral index in brightness of 3C273 as well as a 2D map of the degree of linear polarization. The Sobel operator is applied to the theoretical 2D maps of straight perpendicular jets.
Velocity measurements in jets with application to noise source modeling
2010-01-01
This paper describes an experimental investigation of the statistical properties of turbulent velocity fluctuations in an axisymmetric jet. The focus is on those properties that are relevant to the prediction of noise. Measurements are performed using two single hot-wire anemometers as well as a two-component anemometer. Two-point cross correlations of the axial velocity fluctuations and of the fluctuations in the square of the axial velocity fluctuations are presented. Several reference locations in the jet are used including points on the jet lip and centerline. The scales of the turbulence and the convection velocity are determined, both in an overall sense as well as a function of frequency. The relationship between the second and fourth order correlations is developed and compared wit...
1994-12-31
This paper reviews the results of a long-term program of research into the inception and development of cavitation in the submerged jet, the diagnostic for the cavitation being the pressure fluctuations in the near field of the jet. A revised and extended theoretical analysis is presented which shows that the cavitation does not depend simply on the cavitation number of the flow, but also on a Weber number based on the ambient pressure and the jet diameter, and the total dissolved gas content measured relative to the saturation concentration at the ambient pressure. The analysis not only predicts the nondimensional numbers which correlate the experimental data over wide ranges of the principal variables, but also the form of the curve to which the data collapse.
2007-06-13
A method for the simultaneous determination of the energy scales for b-quark jets and light jets, the jet energy resolution, and the top quark mass at hadron colliders is presented. The method exploits the unique kinematics of events with top-antitop pair production, where one of the top quarks involves a leptonic and one a hadronic W boson decay. The paper shows a feasibility study of how this simultaneous measurement can be performed at the upcoming LHC experiments ATLAS and CMS.
Implementation and Performance of the ATLAS Jet Trigger
The ATLAS jet trigger is prepared to cover a variety of physics topics, ranging from QCD studies to searches for SUSY particles. In this paper we will present the challenges of the jet trigger, describing the implementation and the expected performance. In particular, we will review the current physics signatures, the expected rates, efficiencies and timing measurements as obtained from MC studies. Comparisons of the performance obtained with the two different granularities at LVL2 and different EF algorithms will be shown. An overview of teh implications of the trigger performance in the physics studies that include jet signatures will be shown.
Outflow collimation in young stellar objects
1997-10-24
In this paper we explore the effect of radiative losses on purely hydrodynamic jet collimation models applicable to Young Stellar Objects (YSOs). In our models aspherical bubbles form from the interaction of a central YSO wind with an aspherical circum-protostellar density distribution. Building on a previous non-radiative study (Frank & Mellema 1996) we demonstrate that supersonic jets are a natural and robust consequence of aspherical wind-blown bubble evolution. The simulations show that the addition of radiative cooling makes the hydrodynamic collimation mechanisms studied by Frank & Mellema (1996) more effective. An unexpected result is the production of cool, dense jets forming through conical converging flows at the poles of the bubbles. For steady winds the formation of these jets occurs early in the bubble evolution. At later times we find that the dynamical and cooling time scales for the jet material become similar. Since observations of YSO jets show considerable variability in the jet beam we present a simple one-dimensional (1-D) model for the evolution of a variable wind interacting with an accreting environment. These models indicate that, in the presence of a varying protostellar wind, the hydrodynamic collimation processes studied in our simulations can produce cool jets with sizes and time scales consistent with observations.
Distance effect on the behavior of an impinging swirling jet by PIV and flow visualizations
2010-01-01
The present paper deals with the problem of an impinging swirling jet against a wall. The study concerned a detailed experimental investigation on the jetwall interaction using PIV and flow visualizations over a range of operating conditions in which the distance of the ducted propeller from the wall was changed. The influence of the impingement distance and the swirl number (i.e., ratio between the axial fluxes of the swirl and the axial momentum) as well as the interaction between the jet deformation and the perturbation induced on the wall is discussed in this paper.
2008-09-11
(Abridged) In the first paper of this series, we presented hydrodynamical simulations with radiative cooling of jet models with parameters representative of the symbiotic system MWC 560. These were jet simulations of a pulsed, initially underdense jet in a high-density ambient medium. They were stopped when the jet reached a length of 50 AU. There, however, a transition of the initially underdense jet towards an overdense jet should occur, which should result in changed kinematics. Therefore, we describe two hydrodynamical simulations with cooling beyond this density balance, one with the same parameters as model i in Paper I (now called model i'), which was presented there with and without cooling, and the second with higher gas densities in the jet pulses (model iv'). Hydrodynamical simulations, with a further approximated cooling treatment compared to Paper I, were used to be able to enlarge the computational domain. The transition causes changes in the expansion of the cocoon and therefore the morphology of the jet, e.g. a larger radial width of the jet knots. We investigate the radiation properties of the jets, the bremsstrahlung and optical emissivities, integrated emission maps, and synthetic absorption line profiles. The conclusion that the high observed velocities in CH Cygni, R Aquarii, and MWC 560 favor the models with cooling is unchanged by the transition. The observed parallel features in R Aquarii can be produced by the internal knots or by a variable dense radiative shell of shocked ambient medium. The absorption line profiles show that the real parameters in MWC 560 are closer to model iv' than to model i'.
2006-01-01
The Waste Treatment Plant (WTP) under construction at the Hanford Site will use pulse jet mixer (PJM) technology for mixing and gas retention control applications in tanks expected to contain waste slurries exhibiting a non-Newtonian rheology. This paper presents the results of theoretical and experimental studies undertaken to establish a methodology to perform reduced-scale mixing tests with PJM systems in non-Newtonian fluids. A theoretical model for mixing cavern formation from steady and pulsed jets is developed and compared with data from a single unsteady jet in a yield stress simulant. Dimensional analysis is used to identify the important dimensionless parameters affecting mixing performance in more complex systems. Scaling laws are proposed based on the modeling and dimensional analysis. Experimental validation of the scaling laws governing unsteady jet ...
2008-01-01
Supersonic jets propagation over considerable distances and their interactions with surrounding media is one of the important subjects in astrophysics. Laboratory-created jets have completely different scales, however, typical velocities are the same, and the similarity criteria can be applied to scale them to astrophysical conditions. Moreover, by choosing appropriate pairs of colliding plasmas, one can fulfil the scaling conditions for the radiation emission rates. In this paper we present the results of studies of interaction of laser-created jets with gas-puff plasmas at the PALS laser facility. By varying the gas pressure and composition, the nature of the interaction zone changes from a quasi-adiabatic outflow to a strongly radiation cooling jet. The fine scale structures of the interaction zone are studied by means of optical and x-ray diagnostics, and they ...
JET contribution to ITER fuel cycle issues
2005-07-01
The Joint European Torus (JET) fusion machine is the only device capable of operation with tritium (as fuel) and Be (as plasma facing component), what makes it best suited to study ITER relevant issues. A large variety of activities are performed within the JET Fusion Technology Task Force. In this paper, some topics such as erosion/deposition and material transport, flakes characterization and detritiation techniques are highlighted. Recent results obtained using a pumping cryo-panel and on plasma facing component characterisation are given. Finally, issues that will be addressed in the forthcoming JET work-programme are presented, such as a beryllium main wall for JET and in-situ laser detritiation. (authors)
High-energy emission from microqusars
2008-10-02
If the jets of microquasars carry a significant power in the form of relativistic hadrons, then gamma rays and neutrinos can be produced by interactions with matter and photon fields either external or internal to the jet. In this paper I present some recent results of calculations of the interaction of hadronic jets with 1) matter of the jet itself, 2) photon fields generated by synchrotron radiation of both protons and electrons, and 3) matter external to the jet (e.g. a clumped wind). I briefly discuss neutrino production in these scenarios and the prospects of detection with new gamma-ray instruments. Finally, I make a few comments on the controversy about the nature of LS I +61 303.
Experimental and analytical studies of melt jet-coolant interactions: a synthesis
1999-01-01
Instability and fragmentation of a core melt jet in water have been actively studied during the past 10 years. Several models, and a few computer codes, have been developed. However, there are, still, large uncertainties, both, in interpreting experimental results and in predicting reactor-scale processes. Steam explosion and debris coolability, as reactor safety issues, are related to the jet fragmentation process. A better understanding of the physics of jet instability and fragmentation is crucial for assessments of fuel-coolant interactions (FCIs). This paper presents research, conducted at the Division of Nuclear Power Safety, Royal Institute of Technology (RIT/NPS), Stockholm, concerning molten jet-coolant interactions, as a precursor for premixing. First, observations were obtained from scoping experiments with simulant fluids. Second, the linear ...
Design and performance of an open jet wind tunnel for aero-acoustic measurement
2009-01-01
This paper presents the design and performance of an open jet, blow down wind tunnel that was newly commissioned in the anechoic chamber at the ISVR, University of Southampton, UK. This wind tunnel is intended for the measurement of airfoil trailing edge self-noise but can be extended to other aeroacoustic applications. With the primary objectives of achieving acoustically quiet and low turbulence air jet up to 120m/s through a 0.15mx0.45m nozzle, several novel noise and flow control techniques were implemented in the design. Both the acoustical and aerodynamic performances of the open jet wind tunnel were examined in detail after its fabrication. It is found that the background noise of the facility is adequately low for a wide range of exit jet velocity. The potential core of the free je...
1985-10-01
The 1985 Rapid Excavation and Tunnelling Conference was held in New York, USA, between 16 and 20th June. The article presents discussions on a selection of the 72 papers presented, i.e. research in mechanical rock excavation; a new type of tunnel boring machine; water-jet-assisted mechanical cutters; water jet enhancement of roller cutting; rapid roadway drivage in coal mining; geomechanical rock classification system for assessing roadheader performance; steel linings for vertical openings; roadheader decline development; water jets to assist mechanical cutting; and underground construction for an ore bin.
The physics of $Z^0/\\gamma^*$-tagged jets at the LHC
2010-06-15
Electroweak bosons produced in conjunction with jets in high energy collider experiments is one of the principle final-state channels that can be used to test the accuracy of perturbative Quantum Chromodynamics calculations and to assess the potential to uncover new physics through comparison between data and theory. In this paper we present results for the $Z^0/\\gamma^*$+jet production cross sections at the LHC at leading and next-to-leading orders. In proton-proton reactions we elucidate up to ${\\cal O}(G_F\\alpha_s^2)$ the constraints that jet tagging via the $Z^0/\\gamma^*$ decay dileptons provides on the momentum distribution of jets. In nucleus-nucleus reactions we demonstrate that tagged jets can probe important aspects of the dynamics of quark and gluon propagation in hot and dense nuclear matter and characterize the properties of the medium-induced parton showers in ways not possible with more inclusive measurements. Finally, we present specific predictions for the anticipated suppression of the $Z^0/\\gamma^*$+jet production cross section in the quark-gluon plasma that is expected to be created in central lead-lead collisions at the LHC relative to the naive superposition of independent nucleon-nucleon scatterings.
Estimation of jet grouting parameters in Shahriar dam, Iran
2010-01-01
Jet grouting is a method for improving of soil and its physical characteristics. However, in this method, grouting of cement slurry with high pressure and velocity may cause damaging to soil structure, and then excavated grains of soil are removed from the borehole and replaced with cement slurry. The grains, which are remained around the borehole, mixed with slurry (cement) in-situ, can create an improved mass of soil. This mass is named "Soilcrete". Soilcrete mass has special characteristics such as high strength, low deformability and very low permeability. In this paper, principles of jet grouting and effective parameters have been analyzed. Then the test results obtained from Soilcrete column have been investigated. Finally, the paper concludes with presenting amount of principle jet ...
2008-08-20
The deceleration mechanisms for relativistic jets in active galactic nuclei remain an open question, and in this paper we propose a model which could explain sudden jet deceleration, invoking density discontinuities. This is particularly motivated by recent indications from HYMORS. Exploiting high resolution, numerical simulations, we demonstrate that for both high and low energy jets, always at high Lorentz factor, a transition to a higher density environment can cause a significant fraction of the directed jet energy to be lost on reflection. This can explain how one-sided jet deceleration and a transition to FR I type can occur in HYMORS, which start as FR II (and remain so on the other side). For that purpose, we implemented in the relativistic hydrodynamic grid-adaptive AMRVAC code, the Synge-type equation of state introduced in the general polytropic case by Meliani et al. (2004). We present results for 10 model computations, varying the inlet Lorentz factor from 10 to 20, including uniform or decreasing density profiles, and allowing for cylindrical versus conical jet models. As long as the jet propagates through uniform media, we find that the density contrast sets most of the propagation characteristics, fully consistent with previous modeling efforts. When the jet runs into a denser medium, we find a clear distinction in the decelaration of high energy jets depending on the encountered density jump. For fairly high de nsity contrast, the jet becomes destabilised and compressed, decelerates strongly (up to subrelativistic speeds) and can form knots. We point out differences that are found between cylindrical and conical jet models, together with dynamical details like the Richtmyer-Meshkov instabilities developing at the original contact interface.
2005-09-21
In this first of a series of papers describing polarimetric multifrequency Very Long Baseline Array (VLBA) monitoring of 3C 273 during a simultaneous campaign with the INTEGRAL gamma-ray satellite in 2003, we present 5 Stokes I images and source models at 7 mm. We show that a part of the inner jet (1-2 milliarcseconds from the core) is resolved in a direction transverse to the flow, and we analyse the kinematics of the jet within the first 10 mas. Based on the VLBA data and simultaneous single-dish flux density monitoring, we determine an accurate value for the Doppler factor of the parsec scale jet, and using this value with observed proper motions, we calculate the Lorentz factors and the viewing angles for the emission components in the jet. Our data indicates a significant velocity gradient across the jet with the components travelling near the southern edge being faster than the components with more northern path. We discuss our observations in the light of jet precession model and growing plasma instabilities.
Modelling and Diagnostics of a Supersonic DC Plasma Jet Expanding at Low Pressure
2001-10-01
The Low Pressure Plasma Spraying (LPPS) technology has emerged as a successful process for the deposition of numerous coatings. However, very few fundamental studies have been conducted in order to better understand the various phenomena controlling the process. This paper presents a combined measurement/model approach that is used to map the characteristics of an argon plasma jet in LPPS conditions. The numerical model is validated against enthalpy probe measurements and good agreement is found. The use of a CCD camera confirms the structure of the jet predicted by the model and also shows that the shock-probe distance that is usually neglected should be considered to avoid significant errors in the mapping of the jet. This combined approach is used to overcome the problem related to the use of enthalpy probes in aerodynamic non-equilibrium plasma jets. The model is used to determine the plasma jet static pressure field, otherwise unknown, which is required by the enthalpy probe technique for the mapping of the jet characteristics. (author)
Axial plus tangential entry swirling jet
2010-02-15
This paper presents an experimental investigation on swirling jets with well-defined initial conditions. The axial, radial, and azimuthal velocity components, with their respective fluctuations were measured using high spatial-resolution particle image velocimetry. These detailed measurements allow the initial conditions of the swirling jets to be established and the jets to be characterized using various swirl number definitions. The significance of each term in the swirl number calculations are quantified, and the effect of the common assumptions and simplifications are examined. The characteristics of the jets in relation to the initial conditions are then investigated and compared with the previous studies using similar characterization parameters. Jets with Reynolds number of approximately 5700 and swirl conditions ranging from a non-swirling reference case to high swirl are studied. General properties of swirling jets such as higher spreading rate, higher centerline velocity decay, and higher turbulence level are observed. When the degree of swirl is sufficiently high, vortex breakdown occurs. A swirl number of 0.94 is recorded for a high swirl case prior to vortex breakdown, much higher than the critical swirl number reported in the literature. This behavior is attributed to the effect of the initial conditions on the swirl number calculation. (orig.)
The microtube heat sink with tangential impingement jet and variable fluid properties
2009-07-15
This paper presents the numerical investigation of the microtube heat sink with impingement jet feeding. The inlet channel covers only the quarter of the tube perimeter so the swirl flow is settled in the tubes and the heat transfer between the liquid flow and silicon substrate is improved. The water with the variable physical properties is used as the working fluid and laminar flow regime is considered. The proposed microtube heat sink with impingement jet feeding is compared with classic microtube heat sink in terms of temperature variation along the heated surface and temperature difference. The influence of the temperature dependent physical properties on the fluid flow and heat transfer is analyzed. (orig.)
A self-consistent two-temperature model for the computation of supersonic argon plasma jets
2002-09-07
This paper presents a two-temperature model for compressible plasma flows. This study concentrates on the behaviour of the plasma jet in the expansion region. The conditions used correspond to the conditions of low-pressure plasma spraying, with slightly supersonic conditions with thermal and chemical non-equilibrium. The flow dynamics results are analysed with different turbulence models and appear to be consistent with results previously published by the authors on the dynamics of low-temperature air jets and favour the Reynolds stress turbulence model. Chemical as well as thermal non-equilibrium are studied. (author)
A self-consistent two-temperature model for the computation of supersonic argon plasma jets
2002-01-01
This paper presents a two-temperature model for compressible plasma flows. This study concentrates on the behaviour of the plasma jet in the expansion region. The conditions used correspond to the conditions of low-pressure plasma spraying, with slightly supersonic conditions with thermal and chemical non-equilibrium. The flow dynamics results are analysed with different turbulence models and appear to be consistent with results previously published by the authors on the dynamics of low-temperature air jets and favour the Reynolds stress turbulence model. Chemical as well as thermal non-equilibrium are studied. (author)
Using neural networks with jet shapes to identify b jets in e sup + e sup - interactions
1991-12-15
A feed-forward neural network trained using backpropagation was used to discriminate between b and light quark jets in e{sup +}e{sup -} {yields} Z{sup 0} {yields} qanti q events. The information presented to the network consisted of 25 jet shape variables. The network successfully identified b jets in two- and three-jet events modeled using a detector simulation. The jet identification efficiency for two-jet events was 61% and the probability to call a light quark jet a b jet equal to 20%. (orig.).
Extending CKKW-merging to one-loop matrix elements
2008-01-01
We extend earlier schemes for merging tree-level matrix elements with parton showers to include also merging with one-loop matrix elements. In this paper we make a first study on how to include one-loop corrections, not only for events with a given jet multiplicity, but simultaneously for several different jet multiplicities. Results are presented for the simplest non-trivial case of hadronic events at LEP as a proof of concept
Use of jet pumps to extract oil
1982-01-01
Results are presented from scientific-research and experimental work with jet pumps. A well plan is described into which these pipes are lowered. Advantages are shown for jet pumps and recommendations for their use are given.
An Experimental Investigation of the Flow Structure of Supersonic Impinging Jets
An experimental investigation into the jet structure associated with sound production by a supersonic impinging jet is presented. Large plate impinging tones are investigated for a nozzle pressure ratio (NPR) of 4 and ...
1976-06-01
The purpose of the present treatment is to consider systems where jet momentum and buoyancy are both important. A general equation has been developed to predict the axial decay in thrust-cum-buoyancy controlled unignited free jets and free jet turbulent diffusion flames. By comparison with experimental data, certain conclusions have been drawn regarding the half angle of jet spread and the appropriate stoichiometric or ''analytical'' concentration to 99 percent combustion, to be used for the evaluation of visual flame lengths. The treatment is extended to enclosed jet thrust-controlled and buoyancy-controlled turbulent diffusion flames and the effect of velocity ratio and air fuel ratio on flame length are discussed. In the second part of the paper, separate equations have been formulated for thrust-controlled, buoyancy-controlled and thrust-cum-buoyancy controlled pulverized-coal flames. A discussion has also been presented on the plug flow theory and the mixing zone theory for evaluating flame lengths of pulverized-coal flames.
Symposium proceedings: meeting to mark the retirement of Prof. Donato Palumbo
1987-10-01
A report is given of a special meeting held at the JET Joint Undertaking to mark the retirement of Prof. D. Palumbo at which 8 papers were presented on the history and status of nuclear fusion research in the European Community. (U.K.).
Preliminary Polarization Results at Fermilab Energies
1977-01-01
This paper describes the jet target, the superconducting spectrometer and the polarimeter used to measure the recoil proton polarization in an Indiana University experiment at the Fermi National Accelerator Laboratory. Analysis procedures and data checks are explained and preliminary results are presented and compared with model predictions. The future plans of the experiment are also discussed.
A Parametric Study of Fine-Scale Turbulence Mixing Noise
The present paper is a study of aerodynamic noise spectra from model functions that describe the source. The study is motivated by the need to improve the spectral shape of the MGBK jet noise prediction ...
Integrated plasma shape and boundary flux control on JET tokamak
2008-01-01
Advance tokamak scenarios are gaining more and more importance in operating tokamaks. These scenarios pose challenging control problems, since they require the simultaneous achievement of ambitious plasma parameters. The inherent coupling among the various variables calls for an integrated approach for the design of the controllers. This paper describes an example of integrated design recently implemented at JET: the control of plasma shape and boundary flux. After a brief description of the control problem, the paper focuses on the solution that has been adopted, presenting the technical details of the control scheme. The experimental results included in the paper are in agreement with the expected simulation results, and demonstrate the effectiveness of the proposed solution. (authors)
1997-12-31
Turbulent flows with strong density variations, like helium jets in the ambient air, have specific properties linked with the difference of gas densities. This paper presents some experimental results of turbulence properties inside such flows: the Reynolds tensions and the associated turbulent viscosity, and some characteristics linked with the statistical properties of the different turbulence scales. These last results allows to show the complexity of such flows characterized by the influence of external parameters (Reynolds number, initial density ratio, initial momentum flux) that govern the evolution of these parameters inside the jet from the nozzle up to regions where similarity properties are reached. (J.S.) 12 refs.
Synchronal measurement of flow structure and heat transfer of impingement jet
2010-01-01
This paper will present the characteristics of flow behavior and thermal field of both free and impingement jet issued from a circular orifice nozzle at Re = 8900. The flow behavior of a single round jet and impingement jet was observed by smoke flow visualization recorded by a high speed camera using 5000 frame per second. Heat transfer coefficient on the impingement surface was measured by means of infrared camera (TVS-8500, Avio) with a two-dimensional array of Indeum-Antimony (In Sb) sensors varying in the separation distance between the nozzle and the target plate. The heat transfer coefficient changes in time and spatial. Therefore, the root mean square distribution of the heat transfer was obtained from the data. As a result, it was confirmed that the longitudinal vortex was observe...
QCD, Tevatron results and LHC prospects
2008-01-01
We present a summary of the most recent measurements relevant to Quantum Chromodynamics (QCD) delivered by the D0 and CDF Tevatron experiments by May 2008. CDF and D0 are moving toward precision measurements of QCD based on data samples in excess of 1 fb-1. The inclusive jet cross sections have been extended to forward rapidity regions and measured with unprecedented precision following improvements in the jet energy calibration. Results on dijet mass distributions, bbbar dijet production using tracker based triggers, underlying event in dijet and Drell-Yan samples, inclusive photon and diphoton cross sections complete the list of measurements included in this paper. Good agreement with pQCD within errors is observed for jet production measurements. An improved and consistent theoretical description is needed for photon+jets processes. Collisions at the LHC are ...
Observations of M87 and Hydra A at 90 GHz
2009-02-19
This paper presents new observations of the AGNs M87 and Hydra A at 90 GHz made with the MUSTANG bolometer array on the Green Bank Telescope at 8.5" resolution. A spectral analysis is performed combining this new data and archival VLA data on these objects at longer wavelengths. This analysis can detect variations in spectral index and curvature expected from energy losses in the radiating particles. M87 shows only weak evidence for steepening of the spectrum along the jet suggesting either re-acceleration of the relativistic particles in the jet or insufficient losses to affect the spectrum at 90 GHz. The jets in Hydra A show strong steepening as they move from the nucleus suggesting unbalanced losses of the higher energy relativistic particles. The difference between these two sources may be accounted for by the different lengths over which the jets are observable, 2 kpc for M87 and 45 kpc for Hydra A.
Mueller Navelet jets at LHC - complete NLL BFKL calculation
2010-01-01
We calculate cross section and azimuthal decorrelation of Mueller Navelet jets at the LHC in the complete next-lo-leading order BFKL framework, i.e. including next-to-leading corrections to the Green's function as well as next-to-leading corrections to the Mueller Navelet vertices. The obtained results for standard observables proposed for studies of Mueller Navelet jets show that both sources of corrections are of equal, big importance for final magnitude and final behavior of observables. The astonishing conclusion of our analysis is that the observables obtained within the complete next-lo-leading order BFKL framework of the present paper are quite similar to the same observables obtained within next-to-leading logarithm DGLAP type treatment. This fact sheds doubts on general belief that the studies of Mueller Navelet jets at the LHC will lead to clear ...
2002-10-01
A detailed mathematical model describing the performance of low-pressure low-temperature solar steam-jet cooling cycles for comfort air conditioning is presented in this paper. The model is based on the analysis of the cycle performance together with the supersonic flow conditions in the convergent divergent nozzle and the preceding supersonic and subsonic diffusers. The sets of simultaneous equations resulting from the model together with a subroutine providing numerical values of the thermodynamic properties of steam formulated a computer simulation program. The simulation program analyzes the performance of the solar steam-jet cooling system under different design and operating conditions. A set of design charts for the solar steam-jet cooling cycle and for the selection of the ejector dimensions were constructed. Finally, conclusions on the design considerations and limitations as well as the off design performance are discussed. (author)
Micro-scale synthetic-jet actuator flow simulation with characteristic-based-split method
2009-01-01
Purpose - The purpose of this paper is to present a computational study to investigate the effects of rectangular cavity design of a piezoelectrically driven micro-synthetic-jet actuator on generated flow. Design/methodology/approach - Flow simulations were done using a compressible Navier-Stokes solver, which is based on finite element method implementation of a characteristic-based-split (CBS) algorithm. The algorithm uses arbitrary Lagrangian-Eulerian formulation, which allows to model oscillation of the synthetic jet's diaphragm in a realistic manner. Since all simulated flows are in the slip-flow-regime, a second order slip-velocity boundary condition was applied along the cavity and orifice walls. Flow simulations were done for micro-synthetic-jet configurations with various diaphrag...
2010-01-01
This paper presents the results of a numerical investigation carried out on an alternative jet fan, known in literature like Banana Jet, and it compares its fluid dynamic performances to traditional axial ventilation systems. The alternative jet fan is equipped with inlet/outlet sections inclined at a fixed pitch angle (a) toward the tunnel floor. This approach establishes an alternative solution that is able to provide a safety level equivalent to the traditional solution, in different scenarios. Both systems are installed in an one-way tunnel and two different scenarios (without vehicles and with traffic jam) are considered, in event of fire. The fire was simulated setting heat flux on Heavy Good Vehicle (HGV) surface and comprehensive of radiative heat flux. Computational Fluid-Dynamic ...
2009-01-01
This paper presents the characterization of a source for soft ionization of organic molecules. This source is based on a plasma jet established at the end of a capillary dielectric barrier discharge at atmospheric pressure. He, Ne and Ar as pure gas or with different concentrations of N2 are used as buffer gas for the plasma jet. Spectroscopic emission measurements are carried out along the plasma jet in and outside the capillary. The intensity variation of N2+ lines, for example emission at 391.4 and 427.8 nm, can be associated with the protonation process which is the basis for the soft ionization. The mechanism of the N2+ production outside the capillary, which is relevant for the protonation of molecules and sustains the production of primary ions, is investigated. The response signal of the ions in a nitrogen ...
Production of radiatively cooled hypersonic plasma jets and links to astrophysical jets
2005-01-01
We will present experimental results on formation of supersonic radiatively cooled plasma jets with dimensionless parameters (Mach number 20, cooling parameter 1 and density contrast ?j/?a 10) similar to those in YSO jets. Two different experimental configurations are used. In the first [1,2] the produced jets are purely hydrodynamic and are used to study deflection of the jets by the cross-wind. The cross wind leads to deflection of the jet through formation of internal oblique shocks in the jet and we will discuss the relevance of these observations to the astrophysical systems. In the second configuration [3] the jets have toroidal magnetic field and the plasma beta in these jets is of the order of unity. We will present experimental data on the dynamics of magnetic bubble surrounding the jet and on the development of m=0,1 instabilities in the jet. Although at later times the ...
An advanced disruption predictor for JET tested in a simulated real-time environment
2010-01-01
Disruptions are sudden and unavoidable losses of confinement that may put at risk the integrity of a tokamak. However, the physical phenomena leading to disruptions are very complex and non-linear and therefore no satisfactory model has been devised so far either for their avoidance or their prediction. For this reason, machine learning techniques have been extensively pursued in the last years. In this paper a real-time predictor specifically developed for JET and based on support vector machines is presented. The main aim of the present investigation is to obtain high recognition rates in a real-time simulated environment. To this end the predictor has been tested on the time slices of entire discharges exactly as in real world operation. Since the year 2000, the experiments at JET have been organized in campaigns named sequentially beginning with campaign C1. In this paper ...
Jet Production in proton-proton collisions at oldmath sqrt (s)=7TeV with ATLAS
We report on the first measurements done with the ATLAS experiment of the characteristics of energetic jets produced in proton-proton collisions at the unprecedentedly reached center of mass energy of 7 TeV. Jets are reconstructed using the anti-kt clustering algorithm with distance parameter R=0.6. The kinematic region presented in this paper corresponds to jets with transverse momentum p_T>30 GeV and rapidity |y_jet|<2.8. In order to have a preliminary assessment of the jet production understanding, the data are compared to predictions based on leading-order QCD matrix elements plus parton shower Monte Carlo simulated events. The results shown are obtained on a data sample corresponding to about 1 nb**-1 of integrated luminosity delivered by the Large Hadron Collider.
Heat transfer enhancement due to cavities in impinging jets
2010-01-01
This paper presents results from a study into the effectiveness of surface cavities in achieving increased heat transfer rates in impinging fluid jets. In this work a cylindrical cavity with an isothermally heated base was introduced beneath a steady fluid jet. The effects on the total heat transfer rate from the cavity were evaluated in a parametric study. Cavity depths up to 6 times the jet diameter were investigated at a range of Reynolds numbers and jet to surface distances. The key parameters affecting the heat transfer were found to be the Reynolds number and the distance between the jet nozzle exit and the cavity base. The effects of these parameters are discussed, and a useful range for each is identified with respect to heat transfer enhancement. The cavity arrangement was found to significantly enhance the heat transfer with the maximum heat transfer from the cavity found to be 33% higher than the heat transfer from a similarly heated flat plate. Publisher: Department of Mechanical Engineering
It is now possible to obtain high resolution sequential photographs of the initial formation and evolution of hypervelocity metal jets formed by shaped charge devices fired in air. Researchers have been frustrated by the high velocity of the jet material and the luminous sheath of hot gases cloaking the jet that made detailed observation of the jet body extremely difficult. The camera system that provides the photographs is a large format multi-frame electro-optic camera, referred to as an IC camera (IC stands for image converter), that utilizes electro-optic shuttering, monochromatic pulsed laser illumination and bandpass filtering to provide sequential pictures (in 3D if desired) with minimal degradation due to luminous air shocks or motion blur. The large format (75mm image plane), short exposure (15 ns minimum), ruby laser illumination and bandpass filtering (monochromatic illumination while excluding extraneous light) produces clear, sharp, images of the detailed surface structure of a metal shaped charge jet during early jet formation, elongation of the jet body, jet tip evolution and subsequent particulation (breakup) of the jet body. By utilizing the new camera system in conjunction with the more traditional rotating mirror high speed cameras, pulsed radiography, and electrical sensors, a maximum amount of, often unique, data can be extracted from a single experiment. This paper was intended primarily as an oral presentation. For purposes of continuity and simplicity in these proceedings, the authors have chosen to concentrate on the development of the IC camera system and its impact on the photography of high speed shaped chargejets.
It is now possible to obtain high resolution sequential photographs of the initial formation and evolution of hypervelocity metal jets formed by shaped charge devices fired in air. Researchers have been frustrated by the high velocity of the jet material and the luminous sheath of hot gases cloaking the jet that made detailed observation of the jet body extremely difficult. The camera system that provides the photographs is a large format multi-frame electro-optic camera, referred to as an IC camera (IC stands for image converter), that utilizes electro-optic shuttering, monochromatic pulsed laser illumination and bandpass filtering to provide sequential pictures (in 3D if desired) with minimal degradation due to luminous air shocks or motion blur. The large format (75mm image plane), short exposure (15 ns minimum), ruby laser illumination and bandpass filtering (monochromatic illumination while excluding extraneous light) produces clear, sharp, images of the detailed surface structure of a metal shaped charge jet during early jet formation, elongation of the jet body, jet tip evolution and subsequent particulation (breakup) of the jet body. By utilizing the new camera system in conjunction with the more traditional rotating mirror high speed cameras, pulsed radiography, and electrical sensors, a maximum amount of, often unique, data can be extracted from a single experiment. This paper was intended primarily as an oral presentation. For purposes of continuity and simplicity in these proceedings, the authors have chosen to concentrate on the development of the IC camera system and its impact on the photography of high speed shaped chargejets.
1995-08-29
It is now possible to obtain high resolution sequential photographs of the initial formation and evolution of hypervelocity metal jets formed by shaped charge devices fired in air. Researchers have been frustrated by the high velocity of the jet material and the luminous sheath of hot gases cloaking the jet that made detailed observation of the jet body extremely difficult. The camera system that provides the photographs is a large format multi-frame electro-optic camera, referred to as an IC camera (IC stands for image converter), that utilizes electro-optic shuttering, monochromatic pulsed laser illumination and bandpass filtering to provide sequential pictures (in 3D if desired) with minimal degradation due to luminous air shocks or motion blur. The large format (75mm image plane), short exposure (15 ns minimum), ruby laser illumination and bandpass filtering (monochromatic illumination while excluding extraneous light) produces clear, sharp, images of the detailed surface structure of a metal shaped charge jet during early jet formation, elongation of the jet body, jet tip evolution and subsequent particulation (breakup) of the jet body. By utilizing the new camera system in conjunction with the more traditional rotating mirror high speed cameras, pulsed radiography, and electrical sensors, a maximum amount of, often unique, data can be extracted from a single experiment. This paper was intended primarily as an oral presentation. For purposes of continuity and simplicity in these proceedings, the authors have chosen to concentrate on the development of the IC camera system and its impact on the photography of high speed shaped chargejets.
Experimental and analytical studies of melt jet-coolant interactions: a synthesis
1998-01-01
Instability and fragmentation of a core melt jet in water have been actively studied during the past ten years. Several models, and a few computer codes, have been developed. However, there are, still, large uncertainties, both, in interpreting experimental results and in predicting reactor-scale processes. Steam explosion and debris coolability, as reactor safety issues, are related to the jet fragmentation process. A better understanding of the physics of jet instability and fragmentation is crucial for assessments of fuel-coolant interactions (FCIs). This paper presents research, conducted at the Division of Nuclear Power Safety, Royal Institute of Technology (RIT/NPS), Stockholm, concerning molten jet-coolant interactions, as a precursor for premixing. First, observations were obtained from scoping experiments with simulant fluids. Second, the linear perturbation method was extended and applied to analyze the interfacial-instability characteristics. Third, two innovative approachs to CFD modeling of jet fragmentation were developed and employed for analysis. The focus of the studies was placed on (a) identifying potential factors, which may affect the jet instability, (b) determining the scaling laws, and (c) predicting the jet behavior for severe accidents conditions. In particular, the effects of melt physical properties, and the thermal hydraulics of the mixing zone, on jet fragmentation were investigated. Finally, with the insights gained from a synthesis of the experimental results and analysis results, a new phenomenological concept, named `macrointeractions concept of jet fragmentation` is proposed. (author)
A kpc-scale X-ray jet in the BL Lac source S5 2007+777
2008-05-08
X-ray jets in AGN are commonly observed in FRII and FRI radio-galaxies, but rarely in BL Lacs, most probably due to their orientation close to the line of sight and the ensuing foreshortening effects. Only three BL Lacs are known so far to contain a kpc-scale X-ray jet. In this paper, we present the evidence for the existence of a fourth extended X-ray jet in the classical radio-selected source S5 2007+777, which for its hybrid FRI/II radio morphology has been classified as a HYMOR (HYbrid MOrphology Radio source). Our Chandra ACIS-S observations of this source revealed an X-ray counterpart to the 19"-long radio jet. Interestingly, the X-ray properties of the kpc-scale jet in S5 2007+777 are very similar to those observed in FRII jets. First, the X-ray morphology closely mirrors the radio one, with the X-rays being concentrated in the discrete radio knots. Second, the X-ray continuum of the jet/brightest knot is described by a very hard power law, with photon index Gamma_x~1, although the uncertainties are large. Third, the optical upper limit from archival HST data implies a concave radio-to-X-ray SED. If the X-ray emission is attributed to IC/CMB with equipartition, strong beaming (delta=13) is required, implying a very large scale (Mpc) jet. The beaming requirement can be somewhat relaxed assuming a magnetic field lower than equipartition. Alternatively, synchrotron emission from a second population of very high-energy elect rons is viable. Comparison to other HYMOR jets detected with Chandra is discussed, as well as general implications for the origin of the FRI/II division.
Fusion of Hydrogen to produce energy is one of the technologies under study to meet the mankind raising need in energy and as a substitute to fossil fuels for the future. This technology is under investigation for more than 30 years already, with, for example, the former construction of the experimental reactors Tore Supra, DIII-D and JET. With the construction of ITER to start, the next step to 'fusion for energy' will be done. In these projects, an extensive use of cryogenic systems is requested. Air Liquide has been involved as cryogenic partner in most of former and presently constructed fusion reactors. In the present paper, a review of the cryogenic systems we delivered to Tore Supra, JET, IPR and KSTAR will be presented.
Hadronic Calibration for the ATLAS Jet Trigger
The ATLAS trigger system must reduce the 40 MHz event rate delivered by the LHC to 200Hz. This is done by selecting online high pT objects. In proton-proton collisions, the main background for jets are also jets. Thus, the main difficulty for the jet trigger is to accurately measure the jet energy, in order to distinguish high pT jets from low pT ones. The measurement of the jet energy scale is a complex issue, specially for non-compensating hadronic calorimeters, like the ATLAS one. This paper describes the strategies used to perform the hadronic calibration for the ATLAS jet trigger.
Lateral jetting technology improves PDC performance theory and practice in the North Sea Beryl Field
1994-12-31
Advances in modern technology continuously present companies with opportunities to improve their products. PDC drill bits have been available for over twenty years, during which time manufacturers have steadily improved the design and quality of their products. Research and development regarding bit profile, cutter types, cutter sizes, cutter layouts and hydraulic configurations has taken place with varying degrees of success. This paper will present a new manufacturing process for PDC drill bits which utilizes a unique bit body material. This technology allows design freedom for a lateral jet hydraulics concept. lateral jets set into the blades of the bit improve the cutter cleaning efficiency. In addition to cleaning the slot in front of it, the jet creates a Venturi effect drawing the fluid across the blades serviced by the downward jets. This flow is then ejected at high speed to the junk slots. Increased efficiency of cutter cleaning has a direct benefit on rate of penetration. Case studies predominantly concerning Mobil Oils Beryl Field in the UK sector North Sea are presented showing direct offsets, to demonstrate the extra footage and ROP obtained by implementation of this technology.
Jet formation and penetration mechanism of W typed shaped charge
Existing classical shaped charges are well known for their longer jets capable of achieving large hole depth to hole diameter ratios in metallic targets. However, in some situations, there arises demand to obtain 1:1 ratio for hole depth to hole diameter which is beyond normal shaped charges capability. A new variant of shape charge, named W typed shape charge (WSC), is proposed in this paper, which can meet the demand of 1:1 ratio, and is based on the geometry that can produce annular jets upon proper initiation scheme. In this paper, we present formation and penetration results of WSC based on three different schemes. We also show that not all WSC designs can form annular jets, only annularly initiated WSC, which also fulfils the ?Internal-External Liners Equal-Impulse? criterion, has the capability to form annular jet. The experimental and numerical results show that when the ratio between annular initiation ring diameter and the charge diameter is 0.75, an annular jet is formed, which was also supported by high speed photographs performed in vacuum. 2D numerical simulations are performed with indigenously developed simulation software, where Eulerian approach with multi-material interface tracking algorithm is utilized, to find various mechanisms involved during jet formation process. The calculation results are found in good agreement with the experimental results, indicating that the interface treatment algorithm proposed in this paper can not only deal with large deformation problem, but also depict clearly the variation of materials interface. It is especially suitable for simulation of the process from liner collapse to formation of shaped charge jet.
The kinematics in the pc-scale jets of AGN The case of S5 1803+784
2010-01-13
We present a kinematic analysis of jet component motion in the VLBI jet of the BL Lac object S5 1803+784, which does not reveal long-term outward motion for most of the components. Understanding the complex kinematic phenomena can possibly provide insights into the differences between quasars and BL Lac objects. The blazar S5 1803+784 has been studied with VLBI at $\\nu$ =1.6, 2.3, 5, 8.4, and 15 GHz between 1993.88 and 2005.68 in 26 observing runs. We (re)analyzed the data and present Gaussian model-fits. We collected the already published kinematic information for this source from the literature and re-identified the components according to the new scenario presented in this paper. Altogether, 94 epochs of observations have been investigated. A careful study of the long-term kinematics reveals a new picture for component motion in S5 1803+784. In contrast to previously discussed motion scenarios, we find that the jet structure within 12 mas of the core can most easily be described by the coexistence of several bright jet features that remain on the long-term at roughly constant core separations (in addition to the already known {\\it stationary} jet component $\\sim$ 1.4 mas) and one faint component moving with an apparent superluminal speed ($\\sim$ 19c, based on 3 epochs). While most of the components maintain long-term roughly constant distances from the core, we observe significant, smooth changes in their position angles. We report on an evolution of the whole jet ridge line with time over the almost 12 years of observations. The width of the jet changes periodically with a period of $\\sim$ 8 to 9 years. We find a correlation between changes in the position angle and maxima in the total flux-density. We present evidence for a geometric origin of the phenomena and discuss possible models.
Searches with early data at CMS
This paper presents an overview of prospects for searches for new physics beyond the Standard Model with early data of the CMS experiment, at the Large Hadron Collider of CERN. The results presented here are based on Monte Carlo simulations of the CMS detector, assuming 10-100~pb$^{-1}$ of collected integrated luminosity and proton-proton collisions at $\\sqrt{s} = 7$~TeV. A selection of benchmark analyses feasible with early data is discussed, including searches for new physics in the di-jet and dilepton+jets channels,
Variables for distinguishing between quark jets and gluon jets
1992-12-31
A reliable method to distinguish light-quark jets from gluon jets would be a useful tool for testing Quantum Chromodynamics in high energy experiments. The motivation for differentiating between light-quark jets and gluon jets in a calorimeter detector is discussed, and a method for accomplishing it is presented. The method is tested using the shower Monte Carlo program HERWIG.
Latest jet results from the Tevatron
2010-05-01
A brief overview of the latest status of jet physics studies at the Tevatron in proton-antiproton collisions at {radical}s = 1.96 TeV is presented. In particular, measurements of the inclusive jet production cross-section, dijet production and searches for new physics, the ratio of the 3-jet to 2-jet production cross-sections, and the three-jet mass are discussed.
Latest jet results from the Tevatron
2010-05-20
A brief overview of the latest status of jet physics studies at the Tevatron in proton-antiproton collisions at $\\sqrt{s}=1.96$~TeV is presented. In particular, measurements of the inclusive jet production cross-section, dijet production and searches for new physics, the ratio of the 3-jet to 2-jet production cross-sections, and the three-jet mass are discussed.
We present the measurement of jet production performed with the ATLAS detector in proton-proton collisions at center-of-mass energy of 7 TeV, using an integrated luminosity of 17 nb$^{-1}$. We show the inclusive jet cross section and jet shapes. Then we discuss the expected performance and strategy for the jet reconstruction in heavy ion collisions.
Identification of photon-tagged jets in the ALICE experiment
2007-11-16
The ALICE experiment at LHC will detect and identify prompt photons and light neutral-mesons with the PHOS detector and the additional EMCal electromagnetic calorimeter. Charged particles will be detected and identified by the central tracking system. In this article, the possibility of studying the interaction of jets with the nuclear medium, using prompt photons as a tool to tag jets, is investigated by simulations. New methods to identify prompt photon-jet events and to distinguish them from the jet-jet background are presented.
2009-01-01
We present the application of a new jet reconstruction algorithm that uses a Gaussian filter to locate and reconstruct the jet energy to Formula Not Shown and heavy ion data from the PHENIX detector. This algorithm is combined with a fake jet rejection scheme that provides efficient jet reconstruction with an acceptable fake rate. We show our first results on the measured jet spectra, and on jet-jet angular correlation in p+p and Cu+Cu collisions.
Hadronic Calorimetry and Jet/$\\tau$/E$_{T}^{miss}$ Performance Studies in ATLAS
Jets, $\\tau$ jets, and missing transverse energy are important components of the physics expected at the LHC. The accurate measurement of the direction and energy of jets, along with missing energy, impose strong requirements upon the performance of the ATLAS detector system. These requirements and the ATLAS Hadronic Calorimetry system are reviewed. A brief discussion of the jet reconstruction algorithms, jet energy scale calibration, and forward jet tagging is also included. The methods and expected accuracy by which $\\tau$ jets are reconstructed and identified is covered. The expected $E_{T}^{miss}$ resolution and minimization of fake high $E_{T}^{miss}$ tails is presented.
Expected performance of ATLAS for measurements of jets, b-jets, tau-jets, and ETmis
Jets and missing energy are among the most important objects of LHC physics. The accuracy of measurements of missing energy and direction and energy of jets put strong requirements on the detector performance. These requirements and the ATLAS Calorimeter system which is projected to fulfill these requirements are presented. The jet reconstruction algorithms and jet energy scale calibration are shortly discussed. Forward jet tagging, b-tagging and tau-tagging are important issues of many physical analyses. Reconstruction of resonances is an example of complex use of calorimeter performance
Event shapes and jet rates in electron-positron annihilation at NNLO
2009-01-01
This article gives the perturbative NNLO results for the most commonly used event shape variables associated to three-jet events in electron-positron annihilation: Thrust, heavy jet mass, wide jet broadening, total jet broadening, C parameter and the Durham three-to-two jet transition variable. In addition the NNLO results for the jet rates corresponding to the Durham, Geneva, Jade-E0 and Cambridge jet algorithms are presented
Event shapes and jet rates in electron-positron annihilation at NNLO
2009-04-08
This article gives the perturbative NNLO results for the most commonly used event shape variables associated to three-jet events in electron-positron annihilation: Thrust, heavy jet mass, wide jet broadening, total jet broadening, C parameter and the Durham three-to-two jet transition variable. In addition the NNLO results for the jet rates corresponding to the Durham, Geneva, Jade-E0 and Cambridge jet algorithms are presented.
2009-01-01
An atmospheric-pressure air-plasma jet operating at 60 Hz ac is presented. A plasma jet with a length of 23 mm was produced by feeding air through a porous alumina dielectric installed between an outer electrode and a hollow inner electrode. Microdischarges in the porous alumina are ejected as a plasma jet from the outer electrode through a 1 mm hole, showing that the temperature of the jet decreases to a value close to the room temperature. The jet disinfects E. coli cells very effectively, eradicating them with an exposure of a few seconds to the jet flame
Simulation of triton burn-up in JET plasmas
1994-07-01
This paper presents the first triton burn-up calculations for JET plasmas using the transport code TRANSP. Four hot ion H-mode deuterium plasmas are studied. For these discharges, the 2.5 MeV emission rises rapidly and then collapses abruptly. This phenomenon is not fully understood but in each case the collapse phase is associated with a large impurity influx known as the ``carbon bloom``. The peak 14 MeV emission occurs at this time, somewhat later than that of the 2.5 MeV neutron peak. The present results give a clear indication that there are no significant departures from classical slowing down and spatial diffusion for tritons in JET plasmas. (authors). 7 refs., 3 figs., 1 tab.
Observations of the initial 3D flow from a ships propeller
2010-01-01
The present paper was aimed at presenting the time-averaged velocity and turbulence intensity at the initial plane from a ships propeller. The flow characteristics of a ships propeller jet are of particular interest for the researchers investigating the jet induced seabed damage as documented in the previous studies. Laser Doppler Anemometry (LDA) measurements show that the axial component of velocity is the main contributor to the velocity magnitude at the initial plane of a ships propeller jet. The tangential component contributes to the rotation while the radial component which contributes to the diffusion, are the second and third largest contributors to the velocity magnitude. The maximum tangential and radial velocity components at the initial plane are approximately 82% and 14% of t...
Langmuir probe diagnostics of a plasma jet system
2009-01-01
Eighty years have passed since Langmuir's first use of the word 'plasma' for describing ionized media. On this occasion we would like to present selected recent results on the application of Langmuir probes to diagnose plasma jet systems. To demonstrate the versatility of the Langmuir probe method we give examples of measurements of the spatial distribution of the plasma parameters as well as their temporal dependence in cases when the plasma jet system operates in a pulsed regime. A part of this paper is devoted to introducing the Langmuir probe technique, especially with regard to its application under conditions when collisions between the charged and neutral particles in the probe sheath cannot be neglected and when the electron energy distribution function in plasma cannot be approximated by a Maxwellian one. In the experimental part we present Langmuir probe measurement ...
2009-01-01
A complete parton level analysis of l+l- + four jets (l = e,mu) and 3lnu + two jets production at the LHC is presented, including all processes at order O(alphaEM6), O(alphaEM4alphaS2) and O(alphaEM2alphaS4) when appropriate. The infinite Higgs mass scenario, which is considered as a benchmark for strong scattering theories and is the limiting case for composite Higgs models, and one example of a model incorporating a Strongly Interacting Light Higgs are confronted with the Standard Model light Higgs predictions. This analysis is combined with the results in the lnu + four jets channel presented in a previous paper, in ...
External inverse-Compton Emission from Blazar Jets
2007-01-01
According to leptonic models for the high-energy emission from blazars, relativistic electrons in the inner jets inverse-Compton scatter photons from a variety of sources. Seed photons are certainly introduced via the synchrotron process from the electrons themselves, but external sources of seed photons may also be present. In this paper, we present detailed derivations of the equations describing external inverse-Compton scattering from two sources of seed photons: direct emission from the accretion disk, and accretion disk photons that have scattered off the broad line region. For each source, we derive the seed photon spectrum incident on the jet, the single electron energy loss rate, and the emitted photon spectrum
External inverse-Compton Emission from Blazar Jets
According to leptonic models for the high-energy emission from blazars, relativistic electrons in the inner jets inverse-Compton scatter photons from a variety of sources. Seed photons are certainly introduced via the synchrotron process from the electrons themselves, but external sources of seed photons may also be present. In this paper, we present detailed derivations of the equations describing external inverse-Compton scattering from two sources of seed photons: direct emission from the accretion disk, and accretion disk photons that have scattered off the broad line region. For each source, we derive the seed photon spectrum incident on the jet, the single electron energy loss rate, and the emitted photon spectrum.
External inverse-Compton Emission from Blazar Jets
According to leptonic models for the high-energy emission from blazars, relativistic electrons in the inner jets inverse-Compton scatter photons from a variety of sources. Seed photons are certainly introduced via the synchrotron process from the electrons themselves, but external sources of seed photons may also be present. In this paper, we present detailed derivations of the equations describing external inverse-Compton scattering from two sources of seed photons: direct emission from the accretion disk, and accretion disk photons that have scattered off the broad line region. For each source, we derive the seed photon spectrum incident on the jet, the single electron energy loss rate, and the emitted photon spectrum.
External inverse-Compton Emission from Blazar Jets
2007-09-25
According to leptonic models for the high-energy emission from blazars, relativistic electrons in the inner jets inverse-Compton scatter photons from a variety of sources. Seed photons are certainly introduced via the synchrotron process from the electrons themselves, but external sources of seed photons may also be present. In this paper, we present detailed derivations of the equations describing external inverse-Compton scattering from two sources of seed photons: direct emission from the accretion disk, and accretion disk photons that have scattered off the broad line region. For each source, we derive the seed photon spectrum incident on the jet, the single electron energy loss rate, and the emitted photon spectrum.
Substructure dependence of jet cross sections at HERA and determination of $\\alpha_{s}$
Jet substructure and differential cross sections for jets produced in the photoproduction and deep inelastic ep scattering regimes have been measured with the ZEUS detector at HERA using an integrated luminosity of 82.2 pb-1. The substructure of jets has been studied in terms of the jet shape and subjet multiplicity for jets with transverse energies Et(jet) > 17 GeV. The data are well described by the QCD calculations. The jet shape and subjet multiplicity are used to tag gluon- and quark-initiated jets. Jet cross sections as functions of Et(jet), jet pseudorapidity, the jet-jet scattering angle, dijet invariant mass and the fraction of the photon energy carried by the dijet system are presented for gluon- and quark-tagged jets. The data exhibit the behaviour expected from the underlying parton dynamics. A value of alphas(Mz) of alphas(Mz) = 0.1176 +-0.0009(stat.) -0.0026 +0.0009 (exp.) -0.0072 +0.0091 (th.) was extracted from the measurements of jet shapes in deep inelastic scattering.
Jet Induced Supernovae-Hydrodynamics and Observational Consequences
2000-11-01
Core collapse supernovae (SN) are the final stages of stellar evolution in massive stars during which the central region collapses, forms a neutron star (NS), and the outer layers are ejected. Recent explosion scenarios assumed that the ejection is due to energy deposition by neutrinos into the envelope but detailed models do not produce powerful explosions. There is mounting evidence for an asphericity in the SN which is difficult to explain within this picture. This evidence includes the observed high polarization, pulsar kicks, high velocity iron-group and intermediate-mass elements material observed in remnants, etc. The discovery of highly magnetars revived the idea that the basic mechanism for the ejection of the envelope is related to a highly focused MHD-jet formed at the NS. Our 3-D hydro simulations of the jet propagation through the star confirmed that the mechanism can explain the asphericities. In this paper, detailed 3-D models for jet induced explosions of "classical" core collapse supernovae are presented. We demonstrate the influence of the jet properties and of the underlaying progenitor structure on the final density and chemical structure. Finally, we discuss the observational consequences, predictions and tests of this scenario.
Feasibility of performing in-situ vibration testing of jet pumps at a BWR
2001-07-01
Current methods used to analyze Boiling Water Reactor (BWR) jet pump cracking appear to be overly conservative and may lead to premature or unnecessary repairs. A significant component of this conservatism is the predicted crack growth resulting from flow-induced vibration. At one plant, analysis of jet pump riser cracks predicted crack growth that resulted in a mid-cycle shutdown and repair at two welds. For both welds, successive examinations showed no crack growth. It is possible with more accurate input that these repairs could have been scheduled during a normal refueling outage, thereby eliminating the forced shutdown. It is also possible that the repairs could have been completely eliminated, based on more accurate knowledge of stresses due to flow-induced vibration. The objective of this paper is to present methods for monitoring and/or collecting vibration data at selected jet pump locations. The scope of the project described involves assessing methods for inserting instrumentation on selected areas of jet pumps to determine the feasibility of acquiring the needed data. If the feasibility study indicates a reasonable success path, the activities identified in the feasibility study could be undertaken in the future. (author)
Designing high thermal stability jet fuels for the 21st century
1996-12-31
Recently the US Air Force has flown a new JP-8 formulation known as JP-8+100. This new fuel provides a 50% increase in heat sink capability over standard JP-8 and allows the fuel to be stressed to a bulk temperature of 218 C (425 F) and a wetted wall temperature of 260 C (500 F). Despite this advance, fuel system design and engine manufacturers will continue to push the limits of fuel thermal stability. Therefore, additional heat sink capacity will be needed in future jet fuels. This paper describes the current understanding of jet fuel thermal oxidative stability, discusses the role that additives play in increasing the heat sink of current JP-8 fuels, highlights possible schemes for significantly increasing jet fuel heat sink capability, and finally, presents some of the research challenges faced in developing a jet fuel for the 21st century.
Side-entrainment in a jet embedded in a sidewind
2010-09-02
Numerical simulations of HH jets never show side-entrainment of environmental material into the jet beam. This is because the bow shock associated with the jet head pushes the surrounding environment into a dense shell, which is never in direct contact with the sides of the jet beam. We present 3D simulations in which a side-streaming motion (representing the motion of the outflow source through the surrounding medium) pushes the post-bow shock shell into direct contact with the jet beam. This is a possible mechanism for modelling well collimated "molecular jets" as an atomic/ionic flow which entrains molecules initially present only in the surrounding environment.
Stabilization of T-6 jet fuel by mixtures of antioxidants
Work has been reported on synergistic combinations of additives for the stabilization of jet fuels. This paper investigates combinations of the additive KF-1 with dilauryl thiodipropionate (DLTDP). Data on the effects of these additive combinations on the post-test optical density, acidity and peroxide number of T-6 fuel is presented. Attention is also given to combinations of antioxidants with organometallic compounds. The stabilization of T-6 fuel by combination of KF-1 with phenosansesters of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid and pentaerythritol, diethylene glycol, ethylene glycol, and thiodiethylene glycol is investigated.
Stabilization of T-6 jet fuel by mixtures of antioxidants
1985-09-01
Work has been reported on synergistic combinations of additives for the stabilization of jet fuels. This paper investigates combinations of the additive KF-1 with dilauryl thiodipropionate (DLTDP). Data on the effects of these additive combinations on the post-test optical density, acidity and peroxide number of T-6 fuel is presented. Attention is also given to combinations of antioxidants with organometallic compounds. The stabilization of T-6 fuel by combination of KF-1 with phenosansesters of 3,5-di-tert-butyl-4-hydroxyphenylpropionic acid and pentaerythritol, diethylene glycol, ethylene glycol, and thiodiethylene glycol is investigated.
Modeling Study of the Low-Temperature Oxidation of Large Methyl Esters
2009-04-23
This study focuses on the automatic generation by the software EXGAS of kinetic models for the oxidation of large methyl esters using a single set of kinetic parameters. The obtained models allow to well reproduce the oxidation of n-decane / methyl palmitate mixture in a jet-stirred reactor. This paper also presents the construction and a comparison of models for methyl esters from C7 up to C17 in terms f conversion in a jet-stirred reactor and of ignition delay time in a shock tube. This comparison study showed that methyl esters larger than methyl octanoate behave similarly and have very close reactivities.
Generation of nanometer particles by gas condensation in a supersonic jet
1994-12-31
In order to take advantage of the unique properties of nanophase materials, techniques and processes have to developed which provide for sufficient yields with good control. This paper describes a process whereby the nanoclusters of zinc are produced by nucleation of a zinc vapor in a supersonic jet and collected by thermophoresis on a surface cooled by liquid nitrogen. The effects of metal vapor fraction and back pressure on cluster size are presented as well as information n the hardness of nanocrystalline zinc. The results show the scheme works to produce nanophase materials but must be extended to higher temperature operation and produce higher yields in a continuous process to be viable for an industrial application.
The paper presents an analysis of the formation of a dark spot (an atmospheric 'hole') in the resonant dayglow oxygen emission at 130 nm in the thermosphere in the case when a supersonic gas jet enters this region from above (e.g., from the thrusters of the Space Shuttle or the Buran, or from the vaporized matter of a 'small comet'). It is shown that, when the view is from above roughly along the jet, a mass flow of about 1 kg/sec is sufficient to cause a significant decrease in brightness in a spot with a diameter of about 50 km.
Analysis of striation formation mechanism in abrasive water jet cutting
2008-01-01
In this paper the macro-mechanism of abrasive water jet (AWJ) cutting is studied from the point of cutting front and striation formation analysis. The striation on the surface cut with AWJ is a characteristic phenomena which is strongly present when cutting with high traverse velocities for particular material type and thickness of workpiece. The connection between the cutting front step formation and striation formation is explained through series of experiments, which include visual observations of cutting transparent material and through analogies, which deal with river meandering and wear of pneumatic conveyor bends.
Study on the radial jet velocity distribution of two closely spaced opposed jets
2009-01-01
The experimental and theoretical researches on the radial jet of two opposed jets have been carried out in this paper. The radial velocities of opposed jets with various exit velocities, nozzle diameters and nozzle separations were measured experimentally by a hot-wire anemometer (HWA). The results show that, the normalized radial velocities are self-similar across various radial sections at r
The last of the seven-parton tree amplitudes
2006-11-15
We compute the four-quark plus three-gluon and six-quark plus one-gluon tree level amplitudes using on-shell recursion relations. They are needed for the calculation of the 5-jet cross-section at the Born level, and constitute an essential ingredient for next-to-leading order 4-jet and next-to-next-to-leading order 3-jet production at hadronic colliders. Very compact expressions for all possible helicity configurations are provided, allowing direct implementation in computer codes. With the results presented in this paper, the full set of seven-parton tree amplitudes becomes available.
Solar driven steam jet ejector chiller
2009-01-01
This paper presents a solar driven process to generate cold water for air-conditioning by parabolic trough collectors and a steam jet ejector chiller. The only working fluid in the system is water, which is used as refrigerant and working fluid. The operational behaviour of such a system has been investigated by a small test rig. The investigation shows that the cooling water temperature as well as the cold water temperature has a strong influence on the coefficient of performance of a steam jet ejector chiller. The coefficient of performance reaches high values in part load and at good re-cooling conditions, so that the mean efficiency is clearly higher than the nominal efficiency of the system. A first calculation of profitability leads to specific cold cost of 0.62&z.euro;/kWh in German...
Plasma tubes becoming collimated as a result of magnetohydrodynamic pumping
2010-01-01
Collimated magnetized plasma structures are commonly observed on galactic, stellar, and laboratory scales. The Caltech plasma gun produces magnetically driven plasma jets bearing a striking resemblance to astrophysical jets and solar coronal loops by imposing boundary conditions analogous to those plasmas. This paper presents experimental observations of gun-produced plasma jets that support a previously proposed magnetohydrodynamic (MHD) pumping model [P. M. Bellan, Phys. Plasmas 10, 1999 (2003)] as a universal collimation mechanism. For any initially flared, magnetized plasma tube with a finite axial current, the model predicts (i) magnetic pumping of plasma particles from a constricted region into a bulged region and (ii) tube collimation if the flow slows down at the bulged region leading to accumulation of mass and thus concentrating the azimuthal magnetic ...
Passive mixing control for innovative air diffusion terminal devices for buildings
2010-01-01
This paper presents an innovative concept for optimized air diffusion in buildings. The method uses passive control of air jet through lobed diffusers. An analysis is done experimentally at different scales for a lobed shaped geometry. A cross-shaped jet is characterized first through an isolated orifice and then at the scale of one perforated panel. An intermediary analysis of two coalescent and a row of cross-shaped jets is also proposed. All the results lead to the same conclusion. The lobed diffuser favors the self-induction compared to a reference conventional circular perforated diffuser. The air flow induced in the case of the lobed perforated panel is in average twice as the one of the circular perforated panel. Despite the consequent gain in air induction for the lobed perforated ...
2009-01-01
We present the results of numerical simulations of wave-induced magnetic reconnection in a model of the solar atmosphere. In the magnetic field geometry we study in this paper, the waves, driven by a monochromatic piston and a driver taken from Hinode observations, induce periodic reconnection of the magnetic field, and this reconnection appears to help drive long-period chromospheric jets. By synthesizing spectra for a variety of wavelengths that are sensitive to a wide range of temperatures, we shed light on the often confusing relationship between the plethora of jet-like phenomena in the solar atmosphere, e.g., explosive events, spicules, and other phenomena thought to be caused by reconnection. Our simulations produce spicule-like jets with lengths and lifetimes that match observations, and the spectral signatures of several reconnection events are similar to ...
2009-01-01
It is well known that magnetic pulsations of long periods impulsively occur in accordance with the sudden onset of geomagnetic substorms and drastic enhancement of electrojets in the ionosphere. On the basis of the spontaneous fast reconnection model, the present paper examines the physical mechanism by which both magnetic pulsations and strong electrojets are impulsively driven by the fast (Alfvenic) reconnection jet. When a large-scale plasmoid [or traveling compression region (TCR)], directly caused by the fast reconnection jet, collides with the magnetic loop footpoint, strong electrojets are impulsively driven in a finite extent in the loop footpoint in accordance with the evolution of the current wedge and the generator current circuit. Simultaneously, magnetohydrodynamic (Alfven) waves, accompanied by the TCR, are reflected from the electrojet layer, ...
Experimental study on flue gas purifying of MSW incineration using in-pipe jet adsorption techniques
2008-01-01
This paper presents the experimental research process and results about flue gas purifying of municipal solid wastes (MSW) incineration using in-pipe jet adsorption techniques. MSW incineration was carried out in a fluidized bed test rig, and the flue gas purifying was carried out in an in-pipe jet adsorption test rig. The experimental results are as follows: when the feedstock of activated carbon is 1.6g/Nm3, the desulfurization efficiency is 83%, the denitrification efficiency is 41%, and the dechlorination efficiency is 27%. The order of purifying effect of the three kinds of adsorbents on acidic gases from MSW incineration is activated carbon
A new model of the Central Engine of GRB and the Cosmic Jets
2009-02-17
Despite all the already existing observational data, current models still cannot explain completely the excessive energy output and the time variability of GRB. One of the reasons for this is the lack of a good model of the central engine of GRB. A major problem in the proposed models with a black hole (BH) in the center is that they don't explain the observed evidences of late time activity of the central engine. In this paper we are starting the search for a possible model of that central engine as a rotating compact body of still unknown nature. The formation of jets in the new model lies entirely on the fundamental Teukolsky Master Equation. We demonstrate that this general model can describe the formation of collimated GRB-jets of various forms. Some preliminary results are presented.
90 GHz OBSERVATIONS OF M87 AND HYDRA A
2009-01-01
This paper presents new observations of the active galactic nuclei M87 and Hydra A at 90 GHz made with the MUSTANG array on the Green Bank Telescope at 8.''5 resolution. A spectral analysis is performed combining this new data and archival VLA7The VLA is operated by the National Radio Astronomy Observatory, which is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc. data on these objects at longer wavelengths. This analysis can detect variations in spectral index and curvature expected from energy losses in the radiating particles. M87 shows only weak evidence for steepening of the spectrum along the jet suggesting either re-acceleration of the relativistic particles in the jet or insufficient losses to affect the spectrum at 90 GHz. The jets in Hydra A show strong steepening as they move from the ...
2009-01-01
A series of experimental study was carried out with a special interest on a behavior of impinging liquid jet to a flowing bath of the same liquid. It has been known that the jet bounces from the bath against the gravity even after the penetrating to the liquid bath under a narrow range of condition. This unique behavior is often called as 'the bouncing jet.' Entrainment of ambient gas around the jet results in forming a thin gas layer between the jet and the liquid bath to realize a non-coalescnece jet in the bath. This is a key phenomenon to understand the dynamics of the impinging liquid jet. In the present study the authors focus on this ambient gas entrainment in the system that the impinging jet penetrates to coalesce into the flowing liquid bath. Especially on the evaluation of the thickness of the entrained gas around the penetrated jet
Properties and internal structure of jets produced in soft proton-proton collisions at s = 900 GeV
Preliminary results are presented on the study of charged tracks in jets and the internal jet structure using a sample of proton-proton collisions at a center-of-mass energy of s = 900 GeV collected by the ATLAS detector. Jets with low transverse momenta ( p jet T ) are constructed using the antikt jet algorithm with R = 0.6, and selected with uncorrected transverse momentum p jet T > 7 GeV. The track multiplicity and momentum distribution within jets can be exploited to improve jet calibration and is found to be in good agreement with predictions from Monte Carlo simulations. Jet shape measurements are also reasonably well described by the Monte Carlo simulation.
2006-01-01
We present results of high energy density laboratory experiments on the production of supersonic radiatively cooled plasma jets with dimensionless parameters (Mach number approx30, cooling parameter approx1 and density contrast rhoj/rhoa approx10) similar to those in YSO jets. The jets are produced using two modifications of wire array Z-pinch driven by 1MA, 250ns current pulse of MAGPIE facility at Imperial College London. In the first set of experiments the produced jets are purely hydrodynamic and are used to study deflection of the jets by the plasma cross-wind, including the structure of internal oblique shocks in the jets. In the second configuration the jets are driven by the pressure of the toroidal magnetic field and this configuration is relevant to the astrophysical models of jet launching ...
Characteristics of vertically injected buoyant jets of highly diluted propane
2010-01-01
In coflow jets with the nozzle diameter of O (1 cm) and the fuel jet velocity of O (10 cm/s), the buoyancy induced by the density difference between the fuel and air influences the jet structure appreciably. The present study investigated the behavior of such a buoyant jet numerically and experimentally, especially when the fuel stream had higher density than air. When the fuel jet was composed of propane highly diluted with nitrogen, the fuel jet was decelerated and formed a stagnation region. Consequently, the fuel was carried downstream by the coflow having a circular cone shape. When the fuel was moderately diluted or as the jet velocity increased, numerical results showed the Kelvin-Helmholtz type instability along the mixing layer of the jet. When the fuel jet velocity was relatively...
The kinematics in the pc-scale jets of AGN. The case of S5 1803+784
Context. BL Lac objects show core-jet structures with features moving outwards along the jet. We present a kinematic analysis of jet component motion in the pc-scale jet of the BL Lac object S5 1803+784, which does not reveal long-term outward motion for most of the components. Aims: S5 1803+784 shows complex kinematic phenomena; understanding these provides new insights into the emission processes in BL Lac objects and possibly into the differences between quasars and BL Lac objects. Methods: The blazar S5 1803+784 has been studied with VLBI at ? = 1.6, 2.3, 5, 8.4, and 15 GHz between 1993.88 and 2005.68 in 26 observing runs. We (re)analyzed the data and present Gaussian model-fits. We collected the already published kinematic information for this source from the literature and re-identified the components according to the new scenario presented in this paper. Altogether, 94 epochs of observations have been investigated. Results: A careful study of the long-term kinematics reveals a new picture for jet component motion in S5 1803+784. In contrast to previously discussed motion scenarios, we find that the jet structure within 12 mas of the core can most easily be described by the coexistence of several bright jet features that remain on the long-term at roughly constant core separations (in addition to the already known ?stationary? jet component ~1.4 mas) and one faint component moving with an apparent superluminal speed (~19c, based on 3 epochs). While most of the components maintain long-term roughly constant distances from the core, we observe significant, smooth changes in their position angles. We report on an evolution of the whole jet ridge line with time over the almost 12 years of observations. The width of the jet changes periodically with a period of ~8-9 years. We find a correlation between changes in the position angle and maxima in the total flux-density light-curves. We present evidence for a geometric origin of the observed phenomena and discuss possible models. Conclusions: We find evidence for a significantly different scenario of jet component motion in S5 1803+784 compared to the generally accepted one of outwardly moving jet components, and conclude that the observed phenomena (evolution of the jet ridge line, roughly constant component core separations but with significant position angle changes) can most easily be explained within a geometric model. Figures 15 to 20 and Tables 1, 2, 7, and 8 are only available in electronic form at http://www.aanda.org
A muon collider or a neutrino factory based on a muon storage ring require intense beams of muons that can be generated by a 1-4 MW proton beam incident on a moving target inside a 20-T solenoid magnet, with a mercury jet as a preferred example. This paper addresses the thermodynamic interaction of the intense proton beam with the proposed mercury jet target, and the consequences of the generated pressure waves on the target integrity. Specifically, a 24 GeV proton beam with approximately 16 TP (1 TP = 10{sup 12} protons) per pulse and a pulse length of 2 ns will interact with a 1 cm diameter mercury jet within the 20-Tesla magnetic field. In one option, a train of six such proton pulses is to be delivered on target within 2 {micro}s, in which case the state of the mercury jet following the interaction with each pulse is critical. Using the equation of state for mercury from the SESAME library, in combination with the energy deposition rates calculated the by the hadron interaction code MARS, the induced 3-D pressure field in the target is estimated. The consequent pressure wave propagation and attenuation in the mercury jet is calculated using a transient analysis based on finite element modeling, and the state of the mercury jet at the time of arrival of the subsequent pulse is assessed. Issues associated with the use of a liquid metal jet as a target candidate are addressed. Lastly, some experimental results from the BNL E951 experiment are presented and discussed.
2001-11-11
A muon collider or a neutrino factory based on a muon storage ring require intense beams of muons that can be generated by a 1-4 MW proton beam incident on a moving target inside a 20-T solenoid magnet, with a mercury jet as a preferred example. This paper addresses the thermodynamic interaction of the intense proton beam with the proposed mercury jet target, and the consequences of the generated pressure waves on the target integrity. Specifically, a 24 GeV proton beam with approximately 16 TP (1 TP = 10{sup 12} protons) per pulse and a pulse length of 2 ns will interact with a 1 cm diameter mercury jet within the 20-Tesla magnetic field. In one option, a train of six such proton pulses is to be delivered on target within 2 {micro}s, in which case the state of the mercury jet following the interaction with each pulse is critical. Using the equation of state for mercury from the SESAME library, in combination with the energy deposition rates calculated the by the hadron interaction code MARS, the induced 3-D pressure field in the target is estimated. The consequent pressure wave propagation and attenuation in the mercury jet is calculated using a transient analysis based on finite element modeling, and the state of the mercury jet at the time of arrival of the subsequent pulse is assessed. Issues associated with the use of a liquid metal jet as a target candidate are addressed. Lastly, some experimental results from the BNL E951 experiment are presented and discussed.
The ATLAS program for heavy ion jet studies in the upcoming Pb+Pb collisions will be outlined. With the collision energy provided by the LHC and the hermetic and highly segmented calorimeter, measurements of fully reconstructed jets in heavy on collisions will be possible. Several differential studies that can be performed with fully reconstructed jets will be discussed, with the emphasis on the influence of underlying event. Similar measurements, of jet energy spectra and the jet internal structure, performed in p+p collisions at 7 TeV and 900 GeV with the ATLAS detector will also be presented.
Jet Results and Jet Reconstruction Techniques in p+p and their Prospects in Pb+Pb Collisions in CMS
2010-10-15
Copious production of very energetic jets is expected at the LHC due to the large increase in collision energy. Jet reconstruction at these high center of mass energies will provide crucial leverage to map out the QCD evolution of parton energy loss and a unique insight into the nature of the hot QCD matter. This article presents jet reconstruction techniques and the preliminary jet results in p+p collisions at $\\sqrt{s}=7$ TeV collected by the CMS experiment at the LHC. Jet reconstruction prospects for the heavy ion collisions are also discussed.
Interaction of radio jets with clouds in the ambient medium: Numerical simulations
2009-03-31
Hydrodynamical simulations of jets interacting with clouds moving in the ambient medium of the host galaxy are presented. Clouds with sizes of the order of the jet diameter and smaller, crossing the path of the jet with different speeds are considered. In the case of slow moving clouds the jet is stopped over the brief period of time taken by the cloud to cross the jet. The jet maintains its general morphology in the case of fast moving clouds. Erosion of the clouds leads to redistribution of cloud material to large distances. Such interaction may explain the large outflow velocities observed from pc to kpc scales in the compact radio sources.
2010-10-18
The present study report direct numerical simulation (DNS) of a circular jet and the effect of a large scale perturbation at the jet inlet. The perturbation is used to control the jet for increased spreading. Dual-mode perturbation is obtained by combining an axisymmetric excitation with the helical. In the fluid dynamics videos, an active control of the circular jet at a Reynolds number of 2000 for various frequency ratios (both integer and non-integer) has been demonstrated. When the frequency ratio is fixed to 2, bifurcation of the jet on a plane is evident. However, for a non-integer frequency ratio, the axisymmetric jet is seen to bloom in all directions.
AIAA/SAE/ASCE/ATRIF/TRB international air transportation conference, 1981
1981-01-01
This collection of 18 papers was presented at the meeting; all of the papers ae indexed separately. Subjects covered include jet fuel availability and price trends, flight planning, airliner maintenance for fuel efficiency, airport research and development needs, airport capacity enhancement, aircraft structural crashworthiness, in-flight collision avoidance, aircraft engines, and others.
Jet formation and penetration mechanism of W typed shaped charge
2009-01-01
Existing classical shaped charges are well known for their longer jets capable of achieving large hole depth to hole diameter ratios in metallic targets. However, in some situations, there arises demand to obtain 1:1 ratio for hole depth to hole diameter which is beyond normal shaped charges capability. A new variant of shape charge, named W typed shape charge (WSC), is proposed in this paper, which can meet the demand of 1:1 ratio, and is based on the geometry that can produce annular jets upon proper initiation scheme. In this paper, we present formation and penetration results of WSC based on three different schemes. We also show that not all WSC designs can form annular jets, only annularly initiated WSC, which also fulfils the Internal-External Liners Equal-Impulse? criterion, has t...
Preliminary results are presented on the properties and calibration of jets in the ATLAS detector at the LHC using a sample of proton-proton collisions at a center-of-mass energy of $\\sqrt{s}=7$ TeV. Comparisons of multiple inputs to jet reconstruction and calibration are studied, as well as the properties of charged tracks in jets and the internal jet structure. For some quantities of interest, the effect of the noise modeling is presented using inputs to jet finding with and without noise suppression. The inputs to the different jet calibration schemes developed in ATLAS are studied, and the corrections applied by the calibration schemes validated with data. These studies will help the Monte Carlo tuning effort and provide the first steps towards the successful commissioning of jet calibration in ATLAS.
Making use of the excellent calorimetry of the ATLAS experiment, measurements of the cross-section for jet production and of jet properties in proton-proton interactions at sqrt(s) = 7 TeV will be presented. The corrected and unfolded inclusive cross-section for high-pT jets will be described, together with the cross-section as a function of the invariant di-jet mass. Special emphasis will be given to the discussion of the initial understanding of the jet energy scale. Furthermore, the corrected distribution of the angular difference between the two leading jets will be shown, both for the azimuthal as well as for the polar angle. Also studies of the shape of the observed jets will be presented. All results will be compared to theoretical predictions.
Jet production cross-section and jet properties in pp at sqrt(s) = 7 TeV with the ATLAS detector
Making use of the excellent calorimetry of the ATLAS experiment, measurements of the cross-section for jet production and of jet properties in proton-proton interactions at sqrt(s) = 7 TeV will be presented. The corrected and unfolded inclusive cross-section for high-pT jets will be described, together with the cross-section as a function of the invariant di-jet mass. Special emphasis will be given to the discussion of the initial understanding of the jet energy scale. Furthermore, the corrected distribution of the angular difference between the two leading jets will be shown, both for the azimuthal as well as for the polar angle. Also studies of the shape of the observed jets will be presented. All results will be compared to theoretical predictions.
Three-Dimensional Hydrodynamics Experiments on the National Ignition Facility
The production of supersonic jets of material via the interaction of a strong shock wave with a spatially localized density perturbation is a common feature of inertial confinement fusion and astrophysics. The behavior of two-dimensional (2D) supersonic jets has previously been investigated in detail [J. M. Foster et. al, Phys. Plasmas 9, 2251 (2002)]. In three-dimensions (3D), however, there are new aspects to the behavior of supersonic jets in compressible media. In this paper, the commissioning activities on the National Ignition Facility (NIF) [J. A. Paisner et al., Laser Focus World 30, 75 (1994)] to enable hydrodynamic experiments will be presented as well as the results from the first series of hydrodynamic experiments. In these experiments, two of the first four beams of NIF are used to drive a 40 Mbar shock wave into millimeter scale aluminum targets backed by 100 mg/cc carbon aerogel foam. The remaining beams are delayed in time and are used to provide a point-projection x-ray backlighter source for diagnosing the three-dimensional structure of the jet evolution resulting from a variety of 2D and 3D features. Comparisons between data and simulations using several codes will be presented.
Three-Dimensional Hydrodynamics Experiments on the National Ignition Facility
2004-11-12
The production of supersonic jets of material via the interaction of a strong shock wave with a spatially localized density perturbation is a common feature of inertial confinement fusion and astrophysics. The behavior of two-dimensional (2D) supersonic jets has previously been investigated in detail [J. M. Foster et. al, Phys. Plasmas 9, 2251 (2002)]. In three-dimensions (3D), however, there are new aspects to the behavior of supersonic jets in compressible media. In this paper, the commissioning activities on the National Ignition Facility (NIF) [J. A. Paisner et al., Laser Focus World 30, 75 (1994)] to enable hydrodynamic experiments will be presented as well as the results from the first series of hydrodynamic experiments. In these experiments, two of the first four beams of NIF are used to drive a 40 Mbar shock wave into millimeter scale aluminum targets backed by 100 mg/cc carbon aerogel foam. The remaining beams are delayed in time and are used to provide a point-projection x-ray backlighter source for diagnosing the three-dimensional structure of the jet evolution resulting from a variety of 2D and 3D features. Comparisons between data and simulations using several codes will be presented.
Three-Dimensional Hydrodynamic Experiments on the National Ignition Facility
The production of supersonic jets of material via the interaction of a strong shock wave with a spatially localized density perturbation is a common feature of inertial confinement fusion and astrophysics. The behavior of two-dimensional (2D) supersonic jets has previously been investigated in detail [J. M. Foster et. al, Phys. Plasmas 9, 2251 (2002)]. In three-dimensions (3D), however, there are new aspects to the behavior of supersonic jets in compressible media. In this paper, the commissioning activities on the National Ignition Facility (NIF) [J. A. Paisner et al., Laser Focus World 30, 75 (1994)] to enable hydrodynamic experiments will be presented as well as the results from the first series of hydrodynamic experiments. In these experiments, two of the first four beams of NIF are used to drive a 40 Mbar shock wave into millimeter scale aluminum targets backed by 100 mg/cc carbon aerogel foam. The remaining beams are delayed in time and are used to provide a point-projection x-ray backlighter source for diagnosing the three-dimensional structure of the jet evolution resulting from a variety of 2D and 3D features. Comparisons between data and simulations using several codes will be presented.
Three-Dimensional Hydrodynamic Experiments on the National Ignition Facility
2005-02-09
The production of supersonic jets of material via the interaction of a strong shock wave with a spatially localized density perturbation is a common feature of inertial confinement fusion and astrophysics. The behavior of two-dimensional (2D) supersonic jets has previously been investigated in detail [J. M. Foster et. al, Phys. Plasmas 9, 2251 (2002)]. In three-dimensions (3D), however, there are new aspects to the behavior of supersonic jets in compressible media. In this paper, the commissioning activities on the National Ignition Facility (NIF) [J. A. Paisner et al., Laser Focus World 30, 75 (1994)] to enable hydrodynamic experiments will be presented as well as the results from the first series of hydrodynamic experiments. In these experiments, two of the first four beams of NIF are used to drive a 40 Mbar shock wave into millimeter scale aluminum targets backed by 100 mg/cc carbon aerogel foam. The remaining beams are delayed in time and are used to provide a point-projection x-ray backlighter source for diagnosing the three-dimensional structure of the jet evolution resulting from a variety of 2D and 3D features. Comparisons between data and simulations using several codes will be presented.
A new inclusive secondary vertex algorithm for b-jet tagging in ATLAS
2008-07-15
A new inclusive secondary vertex reconstruction algorithm which exploits the topological structure of weak b- and c-hadron decays inside jets is presented. The primary goal is the application to b-jet tagging. The fragmentation of a b-quark results in a decay chain composed of a secondary vertex from the weakly decaying b-hadron and typically one or more tertiary vertices from c-hadron decays. The decay lengths and charged particle multiplicities involved in these decays, as well as the instrumental resolution, do not allow to separately reconstruct and resolve these vertices efficiently using conventional secondary vertexing algorithms based on the assumption of a common geometrical vertex. These difficulties are partially overcome in the algorithm presented in this paper, that is based on the hypothesis that the primary event vertex and the vertices of the weak b- and c-hadron decays lie on the same line, the flight direction of the b-hadron. The algorithm provides detailed information on the topology of the decay cascade. The algorithm based on this hypothesis is implemented mathematically as an extension of the Kalman Filter formalism for vertex reconstruction and technically as a set of flexible software modules integrated in the ATLAS software framework Athena, which make use of the existing Event Data Model for vertex reconstruction and b-tagging. The application of the algorithm to b-jet tagging is shown.
In this paper we derive one space dimensional, reduced systems of equations (1-D closure models) for viscoelastic free jets. We begin with the three-dimensional system of conservation laws and a Maxwell-Jeffreys constitutive law for an incompressible viscoelastic fluid. First, we exhibit exact truncations to a finite, closed system of 1-D equations based on classical velocity assumptions of von Karman. Next, we demonstrate that the 3-D free surface boundary conditions overconstrain these truncated systems, so that only a very limited class of solutions exist. We then proceed to derive approximate 1-D closure theories through a slender jet asymptotic scaling, combined with appropriate definitions of velocity, pressure and stress unknowns. Our nonaxisymmetric 1-D slender jet models incorporate the physical effects of inertia, viscoelasticity (viscosity, relaxation and retardation), gravity, surface tension, and properties of the ambient fluid, and include shear stresses and time dependence. Previous special 1-D slender jet models correspond to the lowest order equations in the present asymptotic theory by an a posteriori suppression to leading order of some of these effects, and a reduction to axisymmetry. Solutions of the lowest order system of equations in this asymptotic analysis are presented: For the special cases of elliptical inviscid and Newtonian free jets, subject to the effects of surface tension and gravity, our model predicts oscillation of the major axis of the free surface elliptical cross section between perpendicular directions with distance down the jet, and drawdown of the cross section, in agreement with observed behavior. 15 refs.
In this paper we derive one space dimensional, reduced systems of equations (1-D closure models) for viscoelastic free jets. We begin with the three-dimensional system of conservation laws and a Maxwell-Jeffreys constitutive law for an incompressible viscoelastic fluid. First, we exhibit exact truncations to a finite, closed system of 1-D equations based on classical velocity assumptions of von Karman. Next, we demonstrate that the 3-D free surface boundary conditions overconstrain these truncated systems, so that only a very limited class of solutions exist. We then proceed to derive approximate 1-D closure theories through a slender jet asymptotic scaling, combined with appropriate definitions of velocity, pressure and stress unknowns. Our nonaxisymmetric 1-D slender jet models incorporate the physical effects of inertia, viscoelasticity (viscosity, relaxation and retardation), gravity, surface tension, and properties of the ambient fluid, and include shear stresses and time dependence. Previous special 1-D slender jet models correspond to the lowest order equations in the present asymptotic theory by an a posteriori suppression to leading order of some of these effects, and a reduction to axisymmetry. Solutions of the lowest order system of equations in this asymptotic analysis are presented: For the special cases of elliptical inviscid and Newtonian free jets, subject to the effects of surface tension and gravity, our model predicts oscillation of the major axis of the free surface elliptical cross section between perpendicular directions with distance down the jet, and drawdown of the cross section, in agreement with observed behavior. 15 refs.
On defining the un-definable: JETS
1990-01-01
A brief summary is presented of the current status of jet studies in hadron-hadron collisions. The primary focus is on those issues that would benefit from comparisons of jet samples obtained from hadron-hadron collisions, from e{sup +}e{sup {minus}} annihilation events at LEP and from deep inelastic collisions at HERA. The important point is that, to perform this comparison properly, the jet various samples must be obtained using the same jet definition.
On defining the un-definable: JETS
1990-12-31
A brief summary is presented of the current status of jet studies in hadron-hadron collisions. The primary focus is on those issues that would benefit from comparisons of jet samples obtained from hadron-hadron collisions, from e{sup +}e{sup {minus}} annihilation events at LEP and from deep inelastic collisions at HERA. The important point is that, to perform this comparison properly, the jet various samples must be obtained using the same jet definition.
Inclusive jet production at the Tevatron
2006-08-01
Preliminary results on inclusive jet production in proton-antiproton collisions at {radical}s = 1.96 TeV based on 1 fb{sup -1} of CDF Run II data are presented. Measurements are preformed using different jet algorithms in a wide range of jet transverse momentum and jet rapidity. The measured cross sections are compared to next-to-leading order perturbative QCD calculations
ENVIRONMENTAL NOISE POLLUTION CAUSED BY JET AIRCRAFT TRAFFIC
A SURVEY IS PRESENTED OF COMMERCIAL JET AIRCRAFT NOISE PROBLEMS AND POSSIBLE WAYS TO MINIMIZE THESE IN THE VICINITY OF AIRPORTS. ACOUSTIC MEASUREMENTS, SUCH AS PERCEIVED NOISE LEVEL ARE DISCUSSED, AND THE Q-FORMULA FOR ...
2010-07-20
The results from data taken during the last several years at the Relativistic Heavy-Ion Collider (RHIC) will be reviewed in the paper. Several selected topics that further our understanding of constituent quark scaling, jet quenching and color screening effect of heavy quarkonia in the hot dense medium will be presented. Detector upgrades will further probe the properties of Quark Gluon Plasma. Future measurements with upgraded detectors will be presented. The discovery perspectives from future measurements will also be discussed.
Wind Tunnel Investigation of the Effect of Jet-Motor Operation Stability
The effects of jet-motor operation on the stability and control characteristics of two fighter-type airplanes as determined by wind-tunnel tests of 1/5-scale models are presented. It is shown that the action of the jets is ...
2009-02-13
We present a comprehensive review of the physics of hadron and jet production at large transverse momentum in high-energy nucleus-nucleus collisions. Emphasis is put on experimental and theoretical "jet quenching" observables that provide direct information on the (thermo)dynamical properties of hot and dense QCD matter.
Heat transfer in condensation of vapor on a liquid jet
1989-11-01
An analysis of published technique for calculating coefficients of heat transfer from a vapor condensing on a liquid jet is presented. The analytic results of various investigators are compared with each other and with our experimental results. Recommendations are given on calculating the coefficient of heat transfer in condensation of vapor on a liquid jet.
Disintegration of liquid jets and drop drag coefficients in pressurized nitrogen and carbon dioxide
2001-06-01
The aim of the present investigation is to clarify of the basic phenomena at the disintegration of liquid jets in a pressurized gas at up to 35 MPa. This is carried out by the characterization of the forces involved in the disintegration of liquid jets, which are influenced by the physical properties of the phases used. (orig.)
Active Galactic Nuclei, Radio Jets and Acceleration of UHECRs
2009-01-01
We present the general properties of the Active Galactic Nuclei (AGNs) and discuss the origin and structure of jets that are associated to a fraction of these objects. We then we address the problems of particle acceleration at highly relativistic energies and set limits on the luminosity of AGN jets for being origin of UHECRs
Acoustic loads prediction on jet aircraft
A nearfield aircraft noise prediction computer program is presented for the F-22 aircraft. The dominant sources of noise are jet turbulent mixing noise, jet broadband shock noise, and fluctuating pressure under the ...
Dichotomy of Solar Coronal Jets: Standard Jets and Blowout Jets
By examining many X-ray jets in Hinode/X-Ray Telescope coronal X-ray movies of the polar coronal holes, we found that there is a dichotomy of polar X-ray jets. About two thirds fit the standard reconnection picture for coronal jets, and about one third are another type. We present observations indicating that the non-standard jets are counterparts of erupting-loop H? macrospicules, jets in which the jet-base magnetic arch undergoes a miniature version of the blowout eruptions that produce major coronal mass ejections. From the coronal X-ray movies we present in detail two typical standard X-ray jets and two typical blowout X-ray jets that were also caught in He II 304 snapshots from STEREO/EUVI. The distinguishing features of blowout X-ray jets are (1) X-ray brightening inside the base arch in addition to the outside bright point that standard jets have, (2) blowout eruption of the base arch's core field, often carrying a filament of cool (T ~ 104 - 105 K) plasma, and (3) an extra jet-spire strand rooted close to the bright point. We present cartoons showing how reconnection during blowout eruption of the base arch could produce the observed features of blowout X-ray jets. We infer that (1) the standard-jet/blowout-jet dichotomy of coronal jets results from the dichotomy of base arches that do not have and base arches that do have enough shear and twist to erupt open, and (2) there is a large class of spicules that are standard jets and a comparably large class of spicules that are blowout jets.
On deformations of Lie algebroids
2010-04-20
In this paper, we realize the deformation cohomology of a Lie algebroid $A$ introduced by M. Crainic and I. Moerdijk as the cohomology of a subcomplex $(\\Gamma(\\Hom(\\wedge^\\bullet\\jet A,A)_{\\dev A}),\\dM_\\jet)$ of the cochain complex $(\\Gamma(\\Hom(\\wedge^\\bullet\\jet A,A)),\\dM_\\jet)$ associated with the Lie algebroid $\\jet A$ and the representation $\\pi:\\jet A\\longrightarrow\\dev A$, which come from the Lie algebroid structure on $A$.
Study on jet breakup behavior at core disruptive accident for fast breeder reactor
2008-01-01
It is important to estimate the cooling possibility of the molten jet in coolant during a core disruptive accident (CDA) of a fast breeder reactor (FBR). In the present study, the molten jet of U-alloy78 simulating the core material is injected into the water simulating the coolant. The visual data of the molten jet breakup behavior is observed by using the high-speed video camera. The front velocity of the molten jet is estimated by using the image processing technique from the visual data. It shows that the front velocity of the molten jet can be divided into three time regions. In the first region, the front velocity of the molten jet increases. In the second region, the front velocity of the molten jet suddenly decreases. In the third region, the front velocity of the molten jet keeps ...
Study of supersonic, dual, coaxial, swirl jet
2002-07-01
The present study addresses experimental investigations of the supersonic dual coaxial swirl jets which are discharged into the open air. The supersonic swirl jet is emitted from an annular nozzle and the inner nozzle provides the sonic and supersonic free jets ranging from Mach number 1.0. to 2.0. The interactions between the annular swirl and inner sonic/supersonic jets are quantified by the pitot impact and static pressure measurements and visualized by using the Schlieren optical method. The pressure ratios of the annular swirl and inner sonic/supersonic jets are changed below 10.0. The swirl intensity is also varied to investigate the effect of the annular swirl on the sonic/supersonic free jets. The results show that the annular swirl jets significantly change the major characteristics of the sonic/supersonic free jets.
Study of jet transverse structure with CMS experiment at s = 10 TeV
We present a study of the jet transverse structure which could be performed at CMS start up conditions. The analysis corresponds to the first 10 pb^{-1} of proton-proton collisions at s = 10 TeV. Jet transverse structure is studied using the second moment of the jet profile in transverse momentum which reflects the distribution of transverse energy inside the jet cone. Different sources of systematics were considered and a comparison of predictions from different generators (HERWIG++ and PYTHIA) was made. The jet structure differs for quark and gluon initiated jets and the possibility of estimating the fractions of quark and gluon jets from the second moment of the jet profile in transverse momentum is discussed.
Production of radiatively cooled hypersonic plasma jets and links to astrophysical jets
2005-01-01
We present results of high energy density laboratory experiments on the production of supersonic radiatively cooled plasma jets with dimensionless parameters (Mach number approx30, cooling parameter approx1 and density contrast rhoj/rhoa approx 10) similar to those in young stellar objects jets. The jets are produced using two modifications of wire array Z-pinch driven by 1 MA, 250 ns current pulse of MAGPIE facility at Imperial College, London. In the first set of experiments the produced jets are purely hydrodynamic and are used to study deflection of the jets by the plasma cross-wind, including the structure of internal oblique shocks in the jets. In the second configuration the jets are driven by the pressure of the toroidal magnetic field and this configuration is relevant to the ...
Non-perturbative QCD effects in jets at hadron colliders
2007-12-19
We discuss non-perturbative QCD contributions to jet observables, computing their dependence on the jet radius R, and on the colour and transverse momentum of the parton initiating the jet. We show, using analytic QCD models of power corrections as well as Monte Carlo simulations, that hadronisation corrections grow at small values of R, behaving as 1/R, while underlying event contributions grow with the jet area as R^2. We highlight the connection between hadronisation corrections to jets and those for event shapes in e^+e^- and DIS; we note the limited dependence of our results on the choice of jet algorithm; finally, we propose several measurements in the context of which to test or implement our predictions. The results presented here reinforce the motivation for the use of a range of R values, as well as a plurality of infrared-safe jet algorithms, in precision jet studies at hadron colliders.
1991-08-14
The device of the present invention monitors the state of jet pumps used in the inside of a BWR type power plant. A difference pressure monitor monitors a difference pressure caused in each of a plurality of jet pumps. A flowrate monitor monitors the flowrate of a recycling pump for supplying driving water to the jet pumps. Signals from both of the monitors are inputted to a state comparison circuit to compare the jet pump difference pressure relative to the driving water. Then, the jet pump is monitored by comparing the difference pressure of each of the jet pumps relative to the total amount of the jet pumps and the information for the ordinary process amount and occurrence of abnormality are provided to an operator by way of a man-machine interface. As a result, state of the jet pumps can be accurately monitored, thereby enabling to find troubles in an early stage and improve the reliability of the BWR type power plant. (I.S.).
Forward Jet Production in Deep Inelastic Scattering at HERA
The production of forward jets has been measured in deep inelastic ep collisions at HERA. The results are presented in terms of single differential cross sections as a function of the Bjorken scaling variable (x_{Bj}) and as triple differential cross sections d^3 \\sigma / dx_{Bj} dQ^2 dp_{t,jet}^2, where Q^2 is the four momentum transfer squared and p_{t,jet}^2 is the squared transverse momentum of the forward jet. Also cross sections for events with a di-jet system in addition to the forward jet are measured as a function of the rapidity separation between the forward jet and the two additional jets. The measurements are compared with next-to-leading order QCD calculations and with the predictions of various QCD-based models.
Dense plasma source development and jet injection in Globus-M
2008-01-01
Progress in the development of a plasma jet source and its utilization for injection of hydrogen plasma and neutral gas jets into the Globus-M spherical tokamak are presented. The latest version of the high kinetic energy gas and plasma jet source with titanium hydride grains is described. Reproducibility of the gas jet generation was increased due to automatic loading of fresh grains into the source before every shot. It allows producing stable gas release for many discharges. Impurity radiation intensity from the plasma jet was decreased by more than 100 times by preliminary processing titanium hydrate grains and developing a new filter. The result of special experiments on two colliding jets is discussed. It was confirmed that the plasma jet recombines into a gas jet after it escapes the source edge and has a kinetic energy higher than the hydrogen ionization potential. ...
Inclusive jet cross section measurement at D0
2006-09-15
We present a new preliminary measurement of the inclusive jet cross section in pp-bar collisions based on a integrated luminosity of about 0.8 fb-1. The data were acquired using the D0 detector between 2002 and 2005. Jets are reconstructed using an iterative cone algorithm with radius R_cone = 0.7. The inclusive jet cross section is presented as a function of transverse jet momentum and rapidity. Predictions from perturbative QCD in next-to-leading order, plus threshold corrections in 2-loop accuracy describe the shape in the transverse jet momentum.
Next-to-Leading Order Jet Physics with BlackHat
2009-12-31
We present several results obtained using the BlackHat next-to-leading order QCD program library, in conjunction with SHERPA. In particular, we present distributions for vector boson plus 1,2,3-jet production at the Tevatron and at the asymptotic running energy of the Large Hadron Collider, including new Z+3-jet distributions. The Z+2-jet predictions for the second-jet P_T distribution are compared to CDF data. We present the jet-emission probability at NLO in W+2-jet events at the LHC, where the tagging jets are taken to be the ones furthest apart in pseudorapidity. We analyze further the large left-handed W polarization, identified in our previous study, for W bosons produced at high P_T at the LHC.
Direct jet reconstruction in p + p and Cu + Cu at PHENIX
2009-11-19
The Relativistic Heavy Ion Collider collides heavy nuclei at ultrarelativistic energies, creating a strongly interacting, partonic medium that is opaque to the passage of high energy quarks and gluons. Direct jet reconstruction applied to these collision systems provides a crucial constraint on the mechanism for in-medium parton energy loss and jet-medium interactions. However, traditional jet reconstruction algorithm operating in the large soft background at RHIC give rise to fake jets well above the intrinsic production rate of high-pT partons, impeding the detection of the low cross section jet signal at RHIC energies. We developed a new jet reconstruction algorithm that uses a Gaussian filter to locate and reconstruct the jet energy. This algorithm is combined with a fake jet rejection scheme that provides efficient jet reconstruction with acceptable fake rate in a background environment up to the central Au + Au collision at sqrt(s_NN) = 200 GeV. We present results of its application in p + p and Cu + Cu collisions using data from the PHENIX detector, namely p + p cross section, Cu + Cu jet yields, the Cu + Cu nuclear modification factor, and Cu + Cu jet-jet azimuthal correlation.
1994-04-20
Discussions have been given on spray characteristics of an jet impinging flow nozzle with an objective to improve the diesel engine combustion method. An attempt has been made to use strong meander in a jet generated from impingement of initial jet to form uniform sprays and improve the combustion. Observations were given on three kinds of jet impinging flow nozzles that jet impinges at just behind the nozzle outlet, at the outlet, and in a jet hole, as well as on non-evaporative spray from a nozzle with straight jet hole. Their spray characteristics were compared. The observations have used shadow photography that presents spray outline shapes, and continuous photographs of lights scattering on spray cross sections photographed by using sheet-form laser irradiation. Impinging a jet increases the spray angle. Impingements at a jet outlet and its outer section cause a high-concentration portion in the center of a spray to disperse around and accelerate introduction of air in the jet. Impingement inside a jet hole results in less spread in a spray than the impingements at a jet outlet and its outer section. It is preferable that a spray be impinged outside and closer to a jet hole. 3 refs., 9 figs., 2 tabs.
2004-01-01
In this paper, I present results from theoretical and numerical (Monte Carlo) N-particle fully relativistic 4-D analysis of Penrose scattering processes (Compton and gamma-gamma-->e-e+) in the ergosphere of a supermassive or stellar mass Kerr (rotating) black hole. Specifically, the escape conditions and the escaping orbits of the Penrose pair production (gamma-gamma-->e-e+) electrons are analyzed, revealing that these particles escape along jet geodesic trajectories collimated, encircling the polar axis. Such collimated vortical tightly wound coil-like trajectories of relativistic particles are inherent properties of rotating black holes. The helical polar angles of escape for these e-e+ pairs range from 40 degrees to 0.5 degree (for the highest energy particles). These jet distributions are consistent with the astrophysical jets of active galactic nuclei (AGNs) and galactic black holes, and strongly suggest a mechanism for precollimation within the inner radius of the dynamically stable accretion disk.
Website Policies and Important Links Comments
 |
 |
 |
WorldWideScience.org is maintained by the
U.S. Department of Energy's
Office of Scientific and Technical Information as the Operating Agent
for the WorldWideScience Alliance.