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Permeability Upscaling Measured on a Block of Berea Sandstone: Results and Interpretation

Description: To physically investigate permeability upscaling over 13,000 permeability values were measured with four different sample supports (i.e., sample volumes) on a block of Berea Sandstone. At each sample support spatially-exhaustive permeability data sets were measured, subject to consistent flow geometry and boundary conditions, with a specially adapted minipermeameter test system. Here, we present and analyze a subset of the data consisting of 2304 permeability values collected from a single block face oriented normal to stratification. Results reveal a number of distinct and consistent trends (i.e., upscaling) relating changes in key summary statistics to an increasing sample support. Examples include the sample mean and semivariogram range that increase with increasing sample support and the sample variance that decreases. To help interpret the measured mean upscaling we compared it to theoretical models that are only available for somewhat different flow geometries. The comparison suggests that the non-uniform flow imposed by the rninipermeameter coupled with permeability anisotropy at the scale of the local support (i.e., smallest sample support for which data is available) are the primary controls on the measured upscaling. This work demonstrates, experimentally, that it is not always appropriate to treat the local-support permeability as an intrinsic feature of the porous medium; that is, independent of its conditions of measurement.
Date: May 6, 1999
Creator: Tidwell, Vincent C. & Wilson, John L.
Partner: UNT Libraries Government Documents Department


Description: Work focused on the program development phase, which has been successfully completed. A revised timetable has been prepared that reflects the June start date and other modifications associated with internal budgeting problems and the actual versus proposed start dates.
Date: July 27, 1998
Creator: WILSON, TOM
Partner: UNT Libraries Government Documents Department

Experimental divertor similarity database parameters

Description: A set of experimentally-determined dimensionless parameters is proposed for characterizing the regime of divertor operation. The objective is to be able to compare as unambiguously as possible the operation of different divertors and to understand what physical similarities and differences they represent. Examples from Alcator C- Mod are given. 4 refs., 5 figs,. 3 tabs.
Date: December 1, 1995
Creator: Hutchinson, I.H.; LaBombard, B. & Lipschultz, B.
Partner: UNT Libraries Government Documents Department

Do phase transitions survive binomial reducibility and thermal scaling?

Description: First order phase transitions are described in terms of the microcanonical and canonical ensemble, with special attention to finite size effects. Difficulties in interpreting a `caloric curve` are discussed. A robust parameter indicating phase coexistence (univariance) or single phase (bivariance) is extracted for charge distributions. 9 refs., 4 figs.
Date: May 1, 1996
Creator: Moretto, L.G.; Phair, L. & Wozniak, G.J.
Partner: UNT Libraries Government Documents Department

Two-fluid analysis of dimensionally similar discharges

Description: The concept of dimensionless scaling introduces the possibility of determining the required size for a fusion reactor based on data from a single machine. Specifically, all dimensionless quantities other than the normalized gyroradius {rho}* can be simultaneously matched to reactor values in present-day tokamaks. Experiments on DIII-D show that the electrons and ions have distinct {rho}* scalings--for electrons {chi} {proportional_to} {rho}*, while {chi} {proportional_to} {rho}*{sup {minus}1/2} for ions. This observation can unify previous results based on single-fluid analysis, and, in addition, illustrates the danger of using such analysis to extrapolate to a reactor. The {rho}* scaling, coupled with technological limits on the magnetic field strength, determines the minimum size for a reactor. If these {rho}* scalings found on DIII-D hold under reactor-relevant conditions, the confinement will scale unfavorably as {rho}* is reduced to the values expected in a reactor.
Date: December 1, 1994
Creator: Luce, T.C. & Petty, C.C.
Partner: UNT Libraries Government Documents Department

Hadron mass scaling in Regge phenomenology

Description: The authors show that Regge phenomenology is consistent with the only scaling law for the hadron masses, M{sup *}/M = ({alpha}{prime}/{alpha}{prime}{sup *}){sup 1/2}, where asterisk indicates a finite-temperature quantity. Phenomenological models further suggest the following expression of the above scaling in terms of the temperature-dependent gluon condensate: M{sup *}/M = ({alpha}{prime}/{alpha}{prime}{sup *}){sup 1/2} = (<G{sub {mu}{nu}}{sup {alpha}}>{sup *}/<G{sup {alpha}{mu}{nu}}>){sup 1/4}.
Date: December 1998
Creator: Burakovsky, L.
Partner: UNT Libraries Government Documents Department

Impedance Scaling and Impedance Control

Description: When a machine becomes really large, such as the Very Large Hadron Collider (VLHC), of which the circumference could reach the order of megameters, beam instability could be an essential bottleneck. This paper studies the scaling of the instability threshold vs. machine size when the coupling impedance scales in a ``normal`` way. It is shown that the beam would be intrinsically unstable for the VLHC. As a possible solution to this problem, it is proposed to introduce local impedance inserts for controlling the machine impedance. In the longitudinal plane, this could be done by using a heavily detuned rf cavity (e.g., a biconical structure), which could provide large imaginary impedance with the right sign (i.e., inductive or capacitive) while keeping the real part small. In the transverse direction, a carefully designed variation of the cross section of a beam pipe could generate negative impedance that would partially compensate the transverse impedance in one plane.
Date: June 1, 1997
Creator: Chou, W. & Griffin, J.
Partner: UNT Libraries Government Documents Department

Scaling Laws for Mesoscale and Microscale Systems

Description: The set of laws developed and presented here is by no means exhaustive. Techniques have been present to aid in the development of additional scaling laws and to combine these and other laws to produce additional useful relationships. Some of the relationships produced here have yielded perhaps surprising results. Examples include the fifth order scaling law for electromagnetic motor torque and the zero order scaling law for capacitive motor power. These laws demonstrate important facts about actuators in small-scale systems. The primary intent of this introduction into scaling law analysis is to provide needed tools to examine possible areas of the research in small-scale systems and direct research toward more fruitful areas. Numerous examples have been included to show the validity of developing scaling laws based on first principles and how real world systems tend to obey these laws even when many other variables may potentially come into play. Development of further laws may well serve to provide important high-level direction to the continued development of small-scale systems.
Date: August 23, 1999
Creator: Spletzer, Barry
Partner: UNT Libraries Government Documents Department


Description: The work performed during the three previous years can be roughly divided into two main categories: (1) development of advanced modeling techniques; and (2) modeling of arc welding process. The work in the first category comprised the development of the Order of Magnitude Scaling (OMS) technique, which is complementary to numerical modeling techniques such as finite elements, but it provides approximate formulas instead of just numerical results. Borrowing concepts from OMS, another modeling technique based on empirical data was also developed. During this stage special software was also developed. The second category comprised the application of OMS to the three main subsystems of arc welding: the weld pool, the arc, and the electrode. For each of these subsystems they found scaling laws and regimes. With this knowledge, they analyzed the generation of weld pool defects during high current arc welding, proposed a mechanistic description of the process, and possible solutions.
Date: January 1, 2003
Creator: MENDEZ,P.F. & EAGAR, T.W.
Partner: UNT Libraries Government Documents Department

Current scaling of axially radiated power in dynamic hohlraums and dynamic hohlraum load design for ZR.

Description: We present designs for dynamic hohlraum z-pinch loads on the 28 MA, 140 ns driver ZR. The scaling of axially radiated power with current in dynamic hohlraums is reviewed. With adequate stability on ZR this scaling indicates that 30 TW of axially radiated power should be possible. The performance of the dynamic hohlraum load on the 20 MA, 100 ns driver Z is extensively reviewed. The baseline z-pinch load on Z is a nested tungsten wire array imploding onto on-axis foam. Data from a variety of x-ray diagnostics fielded on Z are presented. These diagnostics include x-ray diodes, bolometers, fast x-ray imaging cameras, and crystal spectrometers. Analysis of these data indicates that the peak dynamic radiation temperature on Z is between 250 and 300 eV from a diameter less than 1 mm. Radiation from the dynamic hohlraum itself or from a radiatively driven pellet within the dynamic hohlraum has been used to probe a variety of matter associated with the dynamic hohlraum: the tungsten z-pinch itself, tungsten sliding across the end-on apertures, a titanium foil over the end aperture, and a silicon aerogel end cap. Data showing the existence of asymmetry in radiation emanating from the two ends of the dynamic hohlraum is presented, along with data showing load configurations that mitigate this asymmetry. 1D simulations of the dynamic hohlraum implosion are presented and compared to experimental data. The simulations provide insight into the dynamic hohlraum behavior but are not necessarily a reliable design tool because of the inherently 3D behavior of the imploding nested tungsten wire arrays.
Date: March 1, 2007
Creator: Mock, Raymond Cecil; Nash, Thomas J. & Sanford, Thomas W. L.
Partner: UNT Libraries Government Documents Department

On scaling properties of crossing the third-order resonance in particle accelerator

Description: We study effects of charged particle beams crossing a third-order resonance in an accelerator. The distortion of invariant torus during the resonance crossing is used to set 20% emittance growth or 2.5% of trap fraction as the critical resonance strength. We find a simple scaling law for the critical resonance strength vs the tune ramp rate and the initial emittance. The scaling law can be derived by solving Hamilton's equation of motion with stationary phase condition. Such scaling law can be used to evaluate the performance in high power accelerators, such as the FFAG and cyclotron.
Date: December 1, 2011
Creator: Lee, S.Y.; Pang, X.; Jing, Y.; Luo, T.; U., /Indiana; Ng, K.Y. et al.
Partner: UNT Libraries Government Documents Department


Description: Transverse wakefield effects in the high-gradient accelerating structure of the Two-Beam Accelerator (TBA) [1-3] are analyzed theoretically using three different models. The first is a very simple two-particle model due to Wilson [4]; the second, due to Chao, Richter, and Yao [5], is for a beam with uniform charge distribution, constant betatron wavelength, and a linear wake approximation. Both of these models give analytic scaling laws. The third model has a Gaussian beam (represented by 11 superparticles), energy variation across the bunch, acceleration, variation of betatron focusing with energy, and variation of the wakefield from linearity. The three models are compared, and the third model is used to explore the wakefield effects when accelerator parameters such as energy, energy spread, injection energy, accelerating gradient, and betatron wavelength are varied. Also explored are the sensitivity of the beam to the wakefield profile and to the longitudinal charge distribution. Finally, in consideration of wakefield effects, possible parameters of a TBA are presented.
Date: August 1, 1985
Creator: Selph, F. & Sessler, A.
Partner: UNT Libraries Government Documents Department


Description: The experimental data on the multiplicity distributions for various kinds of secondaries produced in the proton-nucleus interactions in emulsion at 200 GeV/c and the correlations between them are presented and discussed. All the characteristics of heavy prongs (mean values <n{sub b}>, <n{sub g}>, <N{sub h}>, their distributions and correlations) are independent (or have a very weak dependence) on the collisions energy in the range 20-200 GeV/c. The data contradict to the cascade-evaporation model and qualitatively agree with the mechanism of particle emission via the long-lived intermediate states. The observed weak A-dependence ({approx} A{sup 0.15}) of shower particle distributions is in agreement with the calculated ones according to the simplified two-step model. It is shown that the n{sub s}-distributions agree well with KNO scaling law in the 67-200 GeV/c range, but the form of universal {psi}(n{sub s/n{sub s}})-function has a weak A-dependence.
Date: January 1, 1974
Creator: Anzon, Z.V.; Boos, E.G.; Chasnikov, I.Ya.; Kanygina, E.K.; Khomenko, K.I.; Pavlova, N.P. et al.
Partner: UNT Libraries Government Documents Department

Emittance growths in resonance crossing at FFAGs

Description: Scaling laws of the emittance growth for a beam crossing the 6th-order systematic space-charge resonances and the random-octupole driven 4th-order resonance are obtained by numerical multi-particle simulations. These laws can be important in setting the minimum acceleration rate and maximum tolerable resonance strength for the design of non-scaling fixed-field alternating gradient accelerators.
Date: October 1, 2007
Creator: Ng, K.Y.; /Fermilab; Pang, X.; Wang, F.; Wang, X.; Lee, S.Y. et al.
Partner: UNT Libraries Government Documents Department

Characterizing the effects of scale and heating rate on micro-scale explosive ignition criteria.

Description: Laser diode ignition experiments were conducted in an effort to characterize the effects of scale and heating rate on micro-scale explosive ignition criteria. Over forty experiments were conducted with various laser power densities and laser spot sizes. In addition, relatively simple analytical and numerical calculations were performed to assist with interpretation of the experimental data and characterization of the explosive ignition criteria.
Date: January 1, 2005
Creator: Hafenrichter, Everett Shingo & Pahl, Robert J.
Partner: UNT Libraries Government Documents Department

Scaled Accelerator Test for the DARHT-II Downstream Transport System

Description: The second axis of the Dual Axial radiography Hydrodynamic Test (DARHT-II) facility at LANL is currently in the commissioning phase[1]. The beam parameters for the DARHT-II machine will be nominally 18 MeV, 2 kA and 1.6 {micro}s. This makes the DARHT-II downstream system the first system ever designed to transport a high current, high energy and long pulse beam [2]. We will test these physics issues of the downstream transport system on a scaled DARHT-II accelerator with a 7.8-MeV and 660-A beam at LANL before commissioning the machine at its full energy and current. The scaling laws for various physics concerns and the beam parameters selection is discussed in this paper.
Date: October 3, 2005
Creator: Chen, Y.; Blackfield, D. T.; Caporaso, G. J.; Guethlein, G.; McCarrick, J. F.; Paul, A. C. et al.
Partner: UNT Libraries Government Documents Department

New measurements of sextupole field decay and snapback effect on Tevatron dipole magnets

Description: To perform detailed studies of the dynamic effects in superconducting accelerator magnets, a fast continuous harmonics measurement system based on the application of a digital signal processor (DSP) has been built at Fermilab. Using this new system, the dynamic effects in the sextupole field, such as the field decay during the dwell at injection and the rapid subsequent ''snapback'' during the first few seconds of the energy ramp, are evaluated for more than ten Tevatron dipoles from the spare pool. The results confirm the previously observed fast drift in the first several seconds of the sextupole decay and provide additional information on a scaling law for predicting snapback duration. The information presented here can be used for an optimization of the Tevatron and for future LHC operations.
Date: July 1, 2006
Creator: Velev, G.V.; Bauer, P.; Carcagno, R.; DiMarco, J.; Lamm, M.; Orris, D. et al.
Partner: UNT Libraries Government Documents Department

Hadronic resonance production in d + Au collisions at sqrt s NN = 200 GeV at RHIC

Description: We present the first measurements of the {rho}(770){sup 0}, K*(892), {Delta}(1232){sup ++}, {Sigma}(1385), and {Lambda}(1520) resonances in d+Au collisions at {radical}s{sub NN} = 200 GeV, reconstructed via their hadronic decay channels using the STAR detector at RHIC. The masses and widths of these resonances are studied as a function of transverse momentum (p{sub T}). We observe that the resonance spectra follow a generalized scaling law with the transverse mass (m{sub T}). The <p{sub T}> of resonances in minimum bias collisions is compared to the <p{sub T}> of {pi}, K, and {bar p}. The {rho}{sup 0}/{pi}{sup -}, K*/K{sup -}, {Delta}{sup ++}/p, {Sigma}(1385)/{Lambda}, and {Lambda}(1520)/{Lambda} ratios in d + Au collisions are compared to the measurements in minimum bias p + p interactions, where we observe that both measurements are comparable. The nuclear modification factors (R{sub dAu}) of the {rho}{sup 0}, K*, and {Sigma}* scale with the number of binary collisions (N{sub bin}) for p{sub T} > 1.2 GeV/c.
Date: August 22, 2008
Creator: Coll, STAR
Partner: UNT Libraries Government Documents Department

Scaling of Multiplicity Distributions from p Emulsion Collisions at Energies between 6.2-GeV and 300-GeV

Description: The multiplicity distributions from p-nucleus interactions in emulsion are found to be consistent with the KNO semi-inclusive scaling hypothesis for p-p collisions, without any change in parameters. The applicability of the scaling law has been extended from current FNAL energies down to 6.2 GeV. the results indicate a fundamental consistency in the multiplicity distributions, regardless of the size of the target nucleus.
Date: January 1, 1977
Creator: Areti, V.H.; Hebert, C.J.D.; Hebert, J. & U., /Ottawa
Partner: UNT Libraries Government Documents Department

Accelerator physics and technology limitations to ultimate energy and luminosity in very large hadron colliders

Description: The following presents a study of the accelerator physics and technology limitations to ultimate energy and luminosity in very large hadron colliders (VLHCs). The main accelerator physics limitations to ultimate energy and luminosity in future energy frontier hadron colliders are synchrotron radiation (SR) power, proton-collision debris power in the interaction regions (IR), number of events-per-crossing, stored energy per beam and beam-stability [1]. Quantitative estimates of these limits were made and translated into scaling laws that could be inscribed into the particle energy versus machine size plane to delimit the boundaries for possible VLHCs. Eventually, accelerator simulations were performed to obtain the maximum achievable luminosities within these boundaries. Although this study aimed at investigating a general VLHC, it was unavoidable to refer in some instances to the recently studied, [2], 200 TeV center-of-mass energy VLHC stage-2 design (VLHC-2). A more thorough rendering of this work can be found in [3].
Date: December 5, 2002
Creator: al., P. Bauer et
Partner: UNT Libraries Government Documents Department

Behavior of the finite-sized, three-dimensional, Ising model near the critical point

Description: Recent work showing the validity of hyperscaling involved results for finite size systems very near the critical point. The authors study this problem in more detail, and give estimators related to the Binder cumulant ratio which seem to approach the critical temperature from above and below. Based on these results, they estimate that the renormalized coupling constant, computed for the temperature fixed at the critical temperature and then taking the large system-size limit, is about 4.9 {+-} 0.1, and give a likely lower bound for it of 4.5. These estimates are argued to suffice to show the validity of hyperscaling.
Date: May 1, 1996
Creator: Baker, G.A. Jr. & Gupta, R.
Partner: UNT Libraries Government Documents Department