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Free Oscillations of an Atmosphere in Which Temperature Increases Linearly With Height

Description: Note presenting the concept that when the temperature in the atmosphere increases linearly with height, the speed of propagation of long waves does not approach a limit with increasing wave length, as in the case of an atmosphere in which the temperature at great heights is assumed to be constant or decreasing, but increases linearly with the period.
Date: October 1950
Creator: Pekeris, C. L.
Partner: UNT Libraries Government Documents Department
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Stability of Systems Containing a Heat Source - The Rayleigh Criterion

Description: "The stability of systems containing a heat source is examined from the energy point of view. Rayleigh's criterion is derived. In the case of a flame, it is found that Rayleigh's criterion must be modified slightly if the specific-heat ratios of the burned and unburned gases are different" (p. 1).
Date: June 26, 1956
Creator: Chu, Boa-Teh
Partner: UNT Libraries Government Documents Department
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Laminar-boundary-layer oscillations and transition on a flat plate

Description: Report presenting an investigation of oscillations in the laminar boundary layer on a flat plate and their relation to transition to turbulent flow. The characteristics of boundary-layer oscillations were studied most successfully when the oscillations were artificially produced by a vibrating ribbon placed in the boundary layer near the surface. A review of theory regarding laminar-boundary-layer oscillations is provided.
Date: April 1943
Creator: Schubauer, G. B. & Skramstad, H. K.
Partner: UNT Libraries Government Documents Department
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On Nonlinear Self-interaction of Geodesic Acoustic Mode Driven by Energetic Particles

Description: It is shown that nonlinear self-interaction of energetic particle-driven Geodesic Acoustic Mode does not generate a second harmonic in radial electric field using the fluid model. However, kinetic effects of energetic particles can induce a second harmonic in the radial electric field. A formula for the second order plasma density perturbation is derived. It is shown that a second harmonic of plasma density perturbation is generated by the convective nonlinearity of both thermal plasma and ener… more
Date: June 4, 2010
Creator: Fu, G. Y.
Partner: UNT Libraries Government Documents Department
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Chromaticity measurement via the fourier spectrum of transverse oscillations

Description: Turn-by-turn data from a single BPM includes information on the chromaticity in sidebands displaced above and below the betatron frequency by an amount of the synchrotron frequency. It may be necessary to induce small amplitude synchrotron oscillation by giving the beam a small kick. Power spectrum of the BPM data gives clear chromatic sidebands, and they can be applied to the chromaticity measurement in the Fermilab Booster.
Date: August 13, 2004
Creator: Yang, Xi
Partner: UNT Libraries Government Documents Department
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BigBOSS: The Ground-Based Stage IV BAO Experiment

Description: The BigBOSS experiment is a proposed DOE-NSF Stage IV ground-based dark energy experiment to study baryon acoustic oscillations (BAO) and the growth of structure with an all-sky galaxy redshift survey. The project is designed to unlock the mystery of dark energy using existing ground-based facilities operated by NOAO. A new 4000-fiber R=5000 spectrograph covering a 3-degree diameter field will measure BAO and redshift space distortions in the distribution of galaxies and hydrogen gas spanning r… more
Date: April 1, 2009
Creator: Schlegel, David; Bebek, Chris; Heetderks, Henry; Ho, Shirley; Lampton, Michael; Levi, Michael et al.
Partner: UNT Libraries Government Documents Department
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TRANSVERSE COHERENT RESISTIVE INSTABILITIES OF AZIMUTHALLY BUNCHED BEAMS IN PARTICLE ACCELERATORS

Description: The transverse electromagnetic coupling of bunches of particles with each other is investigated theoretically, and shown to incorporate the possibility (due to the effect of nonperfectly conducting vacuum chamber walls) of coherent instability even when the longitudinal distance between bunches is much larger than the transverse dimensions of the vacuum tank. The modes of oscillation in which the bunches move rigidly are investigated; criteria for stability, and expressions for the small amplit… more
Date: April 1, 1966
Creator: Courant, Ernest D. & Sessler, Andrew M.
Partner: UNT Libraries Government Documents Department
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General Cause of Sheath Instability Identified for Low Collisionality Plasma in Devices with Secondary Electron Emission

Description: A condition for sheath instability due to secondary electron emission (SEE) is derived for low collisionality plasmas. When the SEE coefficient of the electrons bordering the depleted loss cone in energy space exceeds unity, the sheath potential is unstable to a negative perturbation. This result explains three different instability phenomena observed in Hall thruster simulations including a newly found state with spontaneous ~20MHz oscillations. When instabilities occur, the SEE propagating be… more
Date: May 11, 2012
Creator: M.C. Campanell, A. Khrabrov and I Kaganovich
Partner: UNT Libraries Government Documents Department
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Chromaticity measurement via the Fourier spectrum of transverse oscillations

Description: Turn-by-turn data from a single BPM includes information on the chromaticity in sidebands displaced above and below the betatron frequency by an amount of the synchrotron frequency. It may be necessary to induce small amplitude synchrotron oscillation by giving the beam a small kick. Power spectrum of the BPM data gives clear chromatic sidebands, and they can be applied to the chromaticity measurement in the Fermilab Booster.
Date: August 1, 2004
Creator: Yang, Xi
Partner: UNT Libraries Government Documents Department
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Simulation of Non-resonant Internal Kink Mode with Toroidal Rotation in NSTX

Description: Plasmas in spherical and conventional tokamaks, with weakly reversed shear q pro le and minimum q above but close to unity, are susceptible to an non-resonant (m, n ) = (1, 1) internal kink mode. This mode can saturate and persist and can induce a (2; 1) seed island for Neoclassical Tearing Mode (NTMs)1 . The mode can also lead to large energetic particle transport and signi cant broadening of beam-driven current. Motivated by these important e ects, we have carried out extensive nonlinear simu… more
Date: July 16, 2013
Creator: Fu, Guoyong
Partner: UNT Libraries Government Documents Department
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Polarized proton experiment in the AGS with a partial snake

Description: In three polarized proton runs at the AGS it was recently shown that the imperfection depolarizing resonances in the AGS can be overcome with a 5% partial snake and the intrinsic depolarizing resonances could be jumped with the pulsed tune-jump quadrupoles even in the presence of the partial snake. For the first time polarized proton beam was accelerated up to the required RHIC injection energy of 25 GeV. No polarization was lost due to the imperfection resonances and the depolarization from mo… more
Date: December 1, 1996
Creator: Huang, H.; Ahrens, L. & Alessi, J.G.
Partner: UNT Libraries Government Documents Department
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Ambient beam motion and its excitation by ghost lines in the Tevatron

Description: Transverse betatron motion of the Tevatron proton beam is measured and analyzed. It is shown that the motion is coherent and excited by external sources of unknown origins. Observations of the time-varying 'ghost lines' in the betatron spectrum are reported. The direct measurement of the rms betatron oscillations amplitude estimates it at about 110 nm at {beta}{sub y} {approx} 900 m. Correspondingly, at the amplitudes at the average beta function location with {beta}{sub y} {approx} 50 m is abo… more
Date: March 1, 2011
Creator: Shiltsev, V.
Partner: UNT Libraries Government Documents Department
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Three-dimensional Numerical Investigation of Electron Transport with Rotating Spoke in a Cylindrical Anode Layer Hall Plasma Accelerator

Description: The oscillation behavior described in [Tang et. al, Phys. Plasmas 19, 073519 (2012)] di ers too greatly from previous experimental and numerical studies to claim observation of the same phenomenon. Most signi cantly, the rotation velocity in [Tang et. al, Phys. Plasmas 19, 073519 (2012)] is three orders of magnitude larger than that of typical \rotating spoke" phenomena. Several physical and numerical considerations are presented to more accurately understand the numerical results of [Tang… more
Date: August 27, 1012
Creator: Ellison, C. Leland; Matyash, K.; Parker, J. B.; Raitses, Y. & Fisch, N. J.
Partner: UNT Libraries Government Documents Department
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Stability of bunched beams against high order nonlinear resonances

Description: For a given tune, beams can be made stable against the effects of isolated high order resonances. However, in a system whose betatron tune is changing, there exists a mechanism for beam loss. This mechanism is discussed and applied to the case of bunched beams, where the synchrotron motion introduces a time variation of tune. A stability criterion for a system with varying tune is presented, together with a set of suggested parameter values. The basic constraint is that the linear tune spread i… more
Date: December 1, 1973
Creator: Month, M.
Partner: UNT Libraries Government Documents Department
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Direct focusing error correction with ring-wide TBT beam position data

Description: Turn-By-Turn (TBT) betatron oscillation data is a very powerful tool in studying machine optics. Hundreds and thousands of turns of free oscillations are taken in just few tens of milliseconds. With beam covering all positions and angles at every location TBT data can be used to diagnose focusing errors almost instantly. This paper describes a new approach that observes focusing error collectively over all available TBT data to find the optimized quadrupole strength, one location at a time. Exa… more
Date: March 1, 2011
Creator: Yang, M. J.
Partner: UNT Libraries Government Documents Department
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Spectral analysis of reltivistic bunched beams

Description: Particles in a storage ring are oscillating in the longitudinal and transverse dimensions, and therefore, the frequency domain is natural for analyzing many beam generated signals. Information ranging from oscillation frequencies to beam phase space distributions can be extracted from the spectral content of these signals. The spectrum of a single particle is like a Green`s function, and it is the key to understanding the spectrum produced by a beam. Three separate cases are consider in an orde… more
Date: May 1, 1996
Creator: Siemann, R.H.
Partner: UNT Libraries Government Documents Department
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Transverse modes of a bunched beam at space charge dominating impedance

Description: Coherent transverse oscillations of a bunched beam are considered at space charge dominated impedance and synchrotron motion taken into account. General equation for the bunch eigenmodes is derived, its exact analytical solution is found for a boxcar bunch at linear synchrotron oscillations, and numerical solutions are presented for other distributions. Both low and high synchrotron frequency approaches are considered and compared, fields of their application are established, and some estimatio… more
Date: June 1, 2009
Creator: Balbekov, V.
Partner: UNT Libraries Government Documents Department
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Charge - dependent increase in coherence of synchrotron oscillation at injection

Description: Because of coupled bunch instability and/or because of some unidentified mechanism, bunches from the 8 GeV Booster accelerator at Fermilab arrive in the Main Injector synchrotron with a complicated centroid distribution in phase and energy. The currently installed broad band kicker provides a maximum of 2 kV, insufficient to remove injection errors before the oscillations would de-cohere, ignoring the influence of bunch charge. Perhaps surprisingly, for sufficient but generally modest charge, t… more
Date: November 1, 2004
Creator: MacLachlan, J. A.
Partner: UNT Libraries Government Documents Department
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Stabilization and onset of sawteeth in TFTR

Description: Measurements from the Tokamak Fusion Test Reactor (TFTR) of the q-profile using motional Stark effect (MSE) polarimetry and the pressure profiles have allowed detailed comparison of both supershots and L-mode discharges to theoretical models describing the stability of sawteeth. In TFTR supershots sawteeth are usually absent, whereas in L-mode discharges they are generally present, and in both cases q(O) is less than one. It has been found that the {omega}*-stabilization criterion of the two-fl… more
Date: March 1, 1994
Creator: Levinton, F. M.; Batha, S. H.; Zakharov, L.; Manickam, J. & Zarnstorff, M. C.
Partner: UNT Libraries Government Documents Department
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MiniBooNE Neutrino Physics at the University of Alabama

Description: This report summarizes the activities conducted by the UA group under the auspices of the DoE/EPSCoR grant number DE--FG02--04ER46112 since the date of the previous progress report, i.e., since November 2005. It also provides a final report of the accomplishments achieved during the entire period of this grant (February 2004 to January 2007). The grant has fully supported the work of Dr. Yong Liu (postdoctoral research assistant -- in residence at Fermilab) on the MiniBooNE reconstruction and p… more
Date: April 27, 2007
Creator: Stancu, Ion
Partner: UNT Libraries Government Documents Department
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Study of Vortex Shedding as Related to Self-Excited Torsional Oscillations of an Airfoil

Description: Note presenting the results of the experimental investigation of the self-excited torsional oscillation of an NACA 0006 airfoil suspended elastically. The relationship between the torsional oscillation and the shedding of vortices was investigated for this airfoil. Two types of oscillation phenomena were found: one was exhibited by cases with angles of attack just above stall and one was exhibited by cases with higher angles of attack.
Date: September 1951
Creator: Chuan, Raymond L. & Magnus, Richard J.
Partner: UNT Libraries Government Documents Department
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