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in subjects: "Orbit Stability"

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Global orbit corrections

There are various reasons for preferring local (e.g., three bump) orbit correction methods to global corrections. One is the difficulty of solving the mN equations for the required mN correcting bumps, where N is the number of superperiods and m is the number of bumps per superperiod. The latter is not a valid reason for avoiding global corrections, since, we can take advantage of the superperiod symmetry to reduce the mN simultaneous equations to N separate problems, each involving only m simu… more

Date: November 1, 1987

Creator: Symon, K.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

60 HZ beam motion reduction at NSLS UV storage ring

A significant reduction in 60 hz beam motion has been achieved in the UV storage ring. From the wide band harmonic beam motion signal, 60 hz signal is extracted by tuned bandpass filter. This signal is processed by the phase and amplitude adjustment circuits and then, it is fed into the harmonic orbit generation circuits. Several harmonics, near the tune, were canceled by employing one circuit for each harmonic. The design and description of this experiment is given in this paper. The results s… more

Date: January 1, 1997

Creator: Singh, O. V.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Fast digital feedback system for energy and beam position stabilization

A digital fast feedback system for beam energy and position stabilization at the target of the CEBAF accelerator is capable of suppressing beam motion in the frequency band from 0 to 80 Hz and also performs narrow band suppression at the first twelve power line harmonics. The system utilizes two VME computers and runs at a 2.4 kHz sampling rate. The numerical algorithm is based on a recursive digital filter with an additional feedforward loop for suppression of high power line harmonics. The sy… more

Date: July 1, 1999

Creator: Dickson, R. & Lebedev, V.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Damping rates of the SRRC storage ring

The SRRC storage ring is a low emittance synchrotron radiation machine with nominal operation energy 1.3 GeV. The design damping time due to synchrotron radiation is 10.7, 14.4, 8.7 ms for the horizontal, vertical and longitudinal plane, respectively. The authors measured the real machine damping time as a function of bunch current, chromaticity, etc. To damp the transverse beam instability, especially in the vertical plane, they need to increase chromaticity to large positive value. The dampin… more

Date: June 1, 1995

Creator: Hsu, K. T.; Kuo, C. C.; Lau, W. K. & Weng, W. T.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

ISA CLOSED ORBIT DISTORTIONS AND CORRECTIONS.

No Description Available.

Date: January 1, 1972

Creator: Crosbie, E.A. & Rowe, E.M.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Report of the SSC impedance workshop

This workshop focused attention on the transverse, single-bunch instability and the detailed analysis of the broadband impedance which would drive it. Issues discussed included: (1) single bunch stability -- impact of impedance frequency shape, coupled-mode vs. fast blowup regimes, possible stopband structure; (2) numerical estimates of transverse impedance of inner bellows and sliding contact shielded bellows; (3) analytic estimates of pickup and kicker impedance contributions; and (4) feasibi… more

Date: October 28, 1985

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Introduction to the measurement of noise with application to particle accelerator beam stabilization.

One of the most important figures of merit for a synchrotron radiation source, once specified beam intensity and energy have been achieved, is charged particle beam stability. While a significant effort has been expended at the Advanced Photon Source (APS) to reduce or eliminate undesirable sources of beam motion, it will be necessary to employ active feedback to stabilize the user photon beams to the very stringent levels required. This becomes especially important when one considers that tran… more

Date: December 21, 1998

Creator: Decker, G.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Some remarks about pseudo-Hamiltonian

For the many applied tasks of accelerator physics, the 4D single particle pseudo-Hamiltonian may be presented as the Hamiltonian of the near-integrable system consisting of integrable and perturbed terms. The KAM theorem states that for sufficiently small perturbation the invariant surfaces continue to exist and, for the systems with two degrees of freedom, completely isolate the thin stochastic layers. As the perturbation strength increases, a transition can occur in which these surfaces disap… more

Date: November 1, 1993

Creator: Malitsky, N.; Bourianoff, G. & Severgin, Yu.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Optimization of the NLC final focus system

An optimization scheme for final focus systems is discussed and applied to the NLC design. The optical functions at the defocusing sextupoles, the sextupole strength, and the length of the system must obey eight conditions that are imposed by the spot size increase due to higher-order aberrations, the effects of synchrotron radiation in the bending magnets, power supply ripple, magnet vibration tolerances, and the estimated orbit stability at the sextupoles. These eight conditions determine the… more

Date: June 1, 1995

Creator: Zimmermann, F.; Helm, R. & Irwin, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Coherent modes for multiple non-rigid bunches in a storage ring

A method is presented for determining the stability of a system consisting of several highly relativistic bunches of charged particles circulating in a storage ring. The particles interact with magnets designed to guide the beam as well as with electromagnetic fields induced by the particles themselves. Previous work has considered modes where all bunches in the ring are executing the same type of internal oscillation. This dissertation considers the results of allowing those modes to couple to… more

Date: March 1, 1996

Creator: Berg, J. S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Accelerator Physics Challenges for the NSLS-II Project

The NSLS-II is an ultra-bright synchrotron light source based upon a 3-GeV storage ring with a 30-cell (15 super-period) double-bend-achromat lattice with damping wigglers used to lower the emittance below 1 nm. In this paper, we discuss the accelerator physics challenges for the design including: optimization of dynamic aperture; estimation of Touschek lifetime; achievement of required orbit stability; and analysis of ring impedance and collective effects.

Date: May 4, 2009

Creator: Krinsky, S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Design considerations on a proton superconducting linac

The authors analyze the longitudinal motion of a single proton in a superconducting linear accelerator. They derive the linearized equations of motion, and develop a matrix formalism to represent the progress of motion. The goal is to provide a tool which can be easily included in a computer code for the design of superconducting proton linacs. In particular they determine the stability conditions, and the amount of motion mismatch resulting from the presence of drift insertions, and from the r… more

Date: August 1, 1995

Creator: Ruggiero, Alessandro G.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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A state variable approach to the BESSY II local beam-position-feedback system

At the BESSY II facility, stability of the electron beam position and angle near insertion devices (IDs) is of utmost importance. Disturbances due to ground motion could result in unwanted broad-bandwidth beam-jitter which decreases the electron (and resultant photon) beam`s effective brightness. Therefore, feedback techniques must be used. Operating over a frequency range of < 1- to > 100-Hz, a local feedback system will correct these beam-trajectory errors using the four bumps around IDs. Thi… more

Date: November 1, 1996

Creator: Gilpatrick, J.D.; Khan, S. & Kraemer, D.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Symplectic tracking using point magnets and a reference orbit made of circular arcs and straight lines

In order to study long term stability, it appears desirable that the particle tracking by symplectic. One way to achieve symplectic tracking is to replace the magnets by a series of point magnets and drift spaces. This approach is modified here by using a reference orbit that is made up of arcs of circles and straight lines which join smoothly with each other. This make sthe symplecticity more evident, and simplifies in some way the particle tracking, as the coordinate system based on this refe… more

Date: June 1, 1993

Creator: Parzen, G.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Coherent electron cooling proof of principle instrumentation design

The goal of the Coherent Electron Cooling Proof-of-Principle (CeC PoP) experiment being designed at RHIC is to demonstrate longitudinal (energy spread) cooling before the expected CD-2 for eRHIC. The scope of the experiment is to longitudinally cool a single bunch of 40 GeV/u gold ions in RHIC. This paper will describe the instrumentation systems proposed to meet the diagnostics challenges. These include measurements of beam intensity, emittance, energy spread, bunch length, position, orbit sta… more

Date: April 15, 2012

Creator: M., Gassner D.; Litvinenko, V.; Michnoff, R.; Miller, T.; Minty, M. & Pinayev, I.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Suppression of beam induced pulse shortening modes in high power RF generator TW output structures

Several different style 11.4 GHz relativistic klystrons, operating with beam pulse widths of 50 ns and using large aperture, tapered phase-velocity TW structures,` have recently demonstrated output RF power levels in the range of 100 to 300 MW without breakdown or pulse shortening. To extend this performance into the long pulse regime (1 {mu}s) or to demonstrate a threefold increase in output power by using higher currents, the existing TW circuit designs must be modified (a) to reduce the cavi… more

Date: December 31, 1992

Creator: Haimson, J. & Mecklenburg, B.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Construction of the Courant-Snyder invariants for the non-linear equations of motion and criterion for the long-term stability of the beam in a storage ring

The Courant-Snyder invariants become Lyapunov functions when the {beta}-functions admit non-zero lower, and finite upper bounds. The long-term stability of motion then follows. This alternative criterion for the long-term stability of motion can be generalized to the nonlinear case. A single particle subjected to an arbitrary static magnetic field is considered in some detail, as an example.

Date: April 26, 1993

Creator: Garczynski, V.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Parametric resonances and stochastic layer induced by a phase modulation

The Hamiltonian system with phase modulation in a higher harmonic rf cavity is experimentally studied on the IUCF cooler ring. The Poincare maps in the resonant rotating frame are obtained from experimental data and compared with numerical tracking. The formation of the stochastic layer due to the overlap of parametric resonances is discussed. The dependence of the stochastic layer on the voltage of the higher harmonic rf cavity, amplitude and frequency of the phase modulation is studied.

Date: December 31, 1995

Creator: Liu, J.Y.; Ball, M. & Brabson, B.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Galaxies and Saturn's rings: Gravitational analogues of nonneutral plasmas

Orbit and collective dynamics in disk galaxies and in Saturn's rings are gravitational analogues of those occurring in nonneutral plasmas. The interesting problems for such ''gravitational plasmas'' are analogous to single-disk studies of transverse dynamics in particle beams. Of particular interest are various orbit-resonances with spiral density and bending waves in these disks which are analogous to electrostatic waves in nonneutral beam plasmas. The background physics, terminology and resul… more

Date: April 25, 1985

Creator: Mark, J.W.K.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Proposed orbit and vertical dispersion correction system for PEP

The scheme for minimization of the rms orbit errors in ISR and SPEAR will be used to correct the closed orbit errors in PEP. The effectiveness of this scheme has been studied for some alignment and field errors in the PEP magnets and position monitors. It has been found for orbit correction system in PEP consisting of 48 correctors and 96 monitors, both horizontal and vertical orbits can be kept below 0.5 mm rms values even allowing for a position monitor alignment error of 0.5 mm rms. This met… more

Date: February 1, 1979

Creator: Close, E.; Cornacchia, M.; King, A. & Lee, M. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Analysis of general circulation model results and comparison with regional climatic data, Task 3. [Progress report]

On time scales of greater than one year the variability of weather and climate on a large path of the Earth is dominated by the Southern Oscillation. While current theories of this phenomenon have clarified the role of the interaction between the ocean and the atmosphere in maintaining this oscillation it has so far been unclear whether the Southern Oscillation originates in the ocean, in the atmosphere or during the interaction between the ocean and the atmosphere. In this study we compared si… more

Date: December 31, 1989

Creator: Cess, R. D. & Hameed, S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Beam position feedback system for the Advanced Photon Source

The Advanced Photon Source (APS) will implement both global and local beam position feedback systems to stabilize the particle and X-ray beams for the storage ring. The systems consist of 20 VME crates distributed around the ring, each running multiple digital signal processors (DSP) running at 4kHz sampling rate with a proportional, integral, and derivative (PID) control algorithm. The particle and X-ray beam position data is shared by the distributed processors through networked reflective me… more

Date: November 1, 1993

Creator: Chung, Y.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Analysis of general circulation model results and comparison with regional climatic data, Task 3

Date: January 1, 1989

Creator: Cess, R.D. & Hameed, S.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Comparisons of model simulations of climate variability with data, Task 2. [Progress report]

Significant progress has been made in our investigations aimed at diagnosing low frequency variations of climate in General Circulation Models. We have analyzed three versions of the Oregon State University General Circulation Model (OSU GCM). These are: (1) the Slab Model in which the ocean is treated as a static heat reservoir of fixed depth, (2) the coupled upper ocean-atmosphere model in which the ocean dynamics are calculated in two layers of variable depths representing the mixed layers a… more

Date: December 31, 1990

Item Type: Report

Partner: UNT Libraries Government Documents Department