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in subjects: "Particle Beams 430200* -- Particle Accelerators-- Beam Dynamics, Field Calculations, & Ion Optics"  
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Three-dimensional free electron laser dispersion relation including betatron oscillations

Description: We have developed a 3-D FEL theory based upon the Maxwell-Vlasov equations including the effects of the energy spread and emittance of the electron beam, and of betatron oscillations. The radiation field is expressed in terms of the Green's function of the inhomogeneous wave equation and the distribution function of the electron beam. The distribution function is expanded in terms of a set of orthogonal functions determined by the unperturbed particle distribution. The coupled Maxwell-Vlasov eq… more
Date: August 1, 1991
Creator: Chin, Y. H.; Kim, K. J. & Xie, M.
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Partner: UNT Libraries Government Documents Department
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Field measurements in pulsed microwigglers

Description: A pulsed microwiggler can provide a large field, greater than 5 T, with a short period, less than 2 mm. It is essential to find a way to measure the field produced in the small bore, with accuracy as well as with high resolution in all three coordinates and the time domain. Conventional field-measuring probes are too large and have poor temporal resolution, but the pulsed-wire technique is well suited to these demands. Los Alamos researchers have made recent improvements to this technique. 9 re… more
Date: January 1, 1991
Creator: Warren, R. (Los Alamos National Lab., NM (United States)) & Preston, D.W. (California State Univ., Hayward, CA (United States))
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Partner: UNT Libraries Government Documents Department
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The Effect of Wiggler Errors on FEL Gain

Description: For an FEL operating in the exponential regime before saturation, we present an analytic description of the effect on the gain of longitudinal velocity variations arising from wiggler field errors. The average gain reduction and the width of the output power distribution are expressed in terms of the mean square average of the ponderomotive phase shift per gain length. A scheme for correcting the electron trajectory using position monitors and dipole correctors is analyzed. Our work is directly… more
Date: January 1, 1991
Creator: Yu, L. H.; Krinsky, S. (Brookhaven National Lab., Upton, NY (United States)); Gluckstern, R. L. & van Zeijts, J. B. J.
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Partner: UNT Libraries Government Documents Department
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Reduction of FEL Gain Due to Wiggler Errors

Description: For an FEL operating in the exponential regime before saturation, we consider the effect on the gain of longitudinal velocity variations arising from wiggler field errors. The average gain reduction and the width of the output power distribution are expressed in terms of the mean square average of the ponderomotive phase shift per gain length. A scheme for correcting the electron trajectory using position monitors and dipole correctors is analyzed. Analytic results are compared with numerical s… more
Date: January 1, 1991
Creator: Yu, L. H.; Krinsky, S.; Friedman, A.; Gluckstern, R. L. & van Zeijts, J. B. J.
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Partner: UNT Libraries Government Documents Department
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Coupled-bunch instabilities in the APS ring

Description: A study of coupled bunch instabilities for the APS storage ring is presented. The instabilities are driven by the higher-order modes of the fifteen 352-MHz single-cell RF cavities. These modes are modeled using the 2-D cavity program URMEL. The program ZAP is then used to estimate the growth time of the instabilities for an equally-spaced bunch pattern. The cavity modes most responsible for the instabilities will be singles out for damping. 7 refs., 5 tabs.
Date: January 1, 1991
Creator: Emery, L.
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Partner: UNT Libraries Government Documents Department
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Review of tolerances at the Final Focus Test Beam

Description: We review the tolerances associated with the Final Focus Test Beam (FFTB). We have computed the acceptability window of the input beam for orbit jitter, emittance beta functions mismatch, incoming dispersion and coupling; tolerances on magnet alignment, strength and multipole content; and the initial tuneability capture of the line. 2 refs., 1 fig.
Date: May 1, 1991
Creator: Bulos, F.; Burke, D.; Helm, R.; Irwin, J.; Roy, G. & Yamamoto, N.
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Partner: UNT Libraries Government Documents Department
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Emittance measurement in a magnetic field

Description: Emittance can be measured by intercepting an electron beam on a range thick plate and then observing the expansion of beamlets transmitted through small holes. The hole size is selected to minimize space charge effects. In the presence of a magnetic field the beamlets have a spiral trajectory and the usual field free formulation must be modified. To interpret emittance in the presence of a magnetic field an envelope equation is derived in the appropriate rotating frame. 1 ref.
Date: April 15, 1991
Creator: Boyd, J.K.
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Partner: UNT Libraries Government Documents Department
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Spin motion of electrons in the SLC linac

Description: It is generally expected that the depolarizing effects of the linear accelerator RF fields will be small. Recently Bill Atwood raised the question whether this conclusion is still correct in view of the fact that the particles in the SLC spend a larger fraction of their time at phase angles off crest'' due to BNS damping; since radial fields are in quadrature with the accelerating field this might imply that depolarizing effects are larger. On the other hand, because of the smaller emittance of… more
Date: January 15, 1991
Creator: Panofsky, W.K.H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The evolution and limits of spectral bandwidth in free electron lasers

Description: We study the bandwidths in free electron lasers (FELs) under different circumstances; for weakly saturated FELs in storage rings, the bandwidth is given be the formula derived in the super mode theory, while it is given by the Fourier transform of the electron pulse length in the strongly saturated FELs in linacs. The limiting bandwidth for the case of a DC beam is given by a Schawlow-Townes formula, but the approach to the limit is very slow. 14 refs.
Date: November 1, 1990
Creator: Kim, K. J.
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Partner: UNT Libraries Government Documents Department
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Achromatic and isochronous electron beam transport for tunable free electron lasers

Description: We have continued the study of a suitable electron beam transport line, which is both isochronous and achromatic, for the free electron laser being designed at Lawrence Berkeley Laboratory. A refined version of the beam transport optics is discussed that accommodates two different modes of FEL wavelength tuning. For the fine tuning involving a small change of the electron beam energy, sextupoles are added to cancel the leading nonlinear dispersion. For the main tuning involving the change of th… more
Date: September 1, 1991
Creator: Bengtsson, J. & Kim, K. J.
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Partner: UNT Libraries Government Documents Department
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An ESME update (v. 7. 2)

Description: The program ESME for modeling the longitudinal degree of freedom of beam dynamics in proton synchrotrons was described in considerable detail in User's Guide to ESME v. 7.1'' distributed about a year ago. This note corrects minor errors and omissions in the User's Guide, discusses bugs and crochets, notes fixes, and reports a few enhancements. Current work and plans are sketched. This note should be adequate to update the User's Guide. 8 refs.
Date: February 11, 1991
Creator: MacLachlan, J.A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Electron beam optics for the FEL experiment and IFEL experiment

Description: Electron beam transport system parameters for the FEL experiment and for the FEL experiment are given. The perturbation of the interaction region'' optics due to wiggler focussing is taken into account and a range of solutions are provided for relevant Twiss parameters in the FEL or IFEL region. Modifications of the transport optics in specific sections of the overall beam transport lines, for reasons of enhanced diagnostic capability or enhanced beam momentum analysis resolution, is also prese… more
Date: January 1, 1990
Creator: van Steenbergen, A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Controlling Multi-Bunches by a Fast Phase Switching

Description: In linear accelerators with two or more bunches the beam loading of one bunch will influence the energy and energy spread the following bunches. This can be corrected by quickly changing the phase of a traveling wave-structure, so that each bunch receives a slightly different net phase. At the SLAC Linear Collider (SLC) three bunches, two (e{sup +},e{sup {minus}}) for the high energy collisions and one (e{sup {minus}}-scavenger) for producing positrons should sit at different phases, due to the… more
Date: September 1, 1990
Creator: Decker, F. J.; Jobe, R. K.; Merminga, N. & Thompson, K. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Wake potentials and impedances for the ATA (Advanced Test Accelerator) induction cell

Description: The AMOS Wakefield Code is used to calculate the impedances of the induction cell used in the Advanced Test Accelerator (ATA) at Livermore. We present the wakefields and impedances for multipoles m = 0, 1 and 2. The ATA cell is calculated to have a maximum transverse impedance of approximately 1000 {Omega}/m at 875 MHz with a quality factor Q = 5. The sensitivity of the impedance spectra to modeling variations is discussed.
Date: September 4, 1990
Creator: Craig, George D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Magnetic bunchers for the generation of high peak current, low emittance electron pulses at medium energy

Description: In this paper, we will outline the various physical constraints and issues for magnetic buncher design. Discussion of achromatic design and dispersion and minimizing rf power will be presented. We will provide generic designs for positive and negative dispersion, and describe the effect of curvature in the energy-phase correlation due to the sinusoidal nature of the rf fields on the output pulse shape. Methods to remove the curvature will be examined. Finally this paper will cover simple nonlin… more
Date: January 1, 1990
Creator: Carlsten, B. E.; McVey, B. D.; Svaton, E. M.; Magelssen, G. R. & Young, L. M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Spin motion of electrons in the SLC linac

Description: It is generally expected that the depolarizing effects of the linear accelerator RF fields will be small. Recently Bill Atwood raised the question whether this conclusion is still correct in view of the fact that the particles in the SLC spend a larger fraction of their time at phase angles off crest'' due to BNS damping; since radial fields are in quadrature with the accelerating field this might imply that depolarizing effects are larger. On the other hand, because of the smaller emittance of… more
Date: November 21, 1990
Creator: Panofsky, W. K. H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Collective Effects in Short Bunches: Summary of the Working Group on Proton Bunches

Description: This report discusses the following topics on proton beam bunching: space charge, a collective but incoherent effect; a very short proton bunch; long proton bunches; transition energy crossing; intrabeam scattering; vacuum related effects; and the issue of mode-coupling for proton bunches. (LSP)
Date: October 10, 1990
Creator: Ruggiero, Alessandro G.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Cumulative Beam Breakup in Radio-Frequency Linacs

Description: An analytic model of cumulative beam breakup has been developed which is applicable to both low-velocity ion and high-energy electron linear accelerators. The model includes arbitrary velocity, acceleration, focusing, initial conditions, beam-cavity resonances, and variable cavity geometry and spacing along the accelerator. The model involves a continuum approximation'' in which the transverse kicks in momentum imparted by the cavities are smoothed over the length of the linac. The resulting eq… more
Date: January 1, 1990
Creator: Bohn, C.L. & Delayen, J.R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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LCLS optics: Selected technological issues and scientific opportunities

Description: The Stanford Linac Coherent Light Source (LCLS) promises to generate photon pulses of unprecedented brevity and peak brightness in the soft x-ray range. In this presentation selected limitations and novel opportunities for technology and science associated with the availability of such pulses will be briefly assessed. Special emphasis will be placed on possible techniques for extending the peak power density and the temporal and spectral regimes of the LCLS output radiation by orders of magnitu… more
Date: March 1, 1993
Creator: Tatchyn, R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The Ion-Channel Laser

Description: A relativistic electron beam propagating through a plasma in the ion-focused regime exhibits an electromagnetic instability at a resonant frequency {omega} {approximately} 2{gamma}{sup 2} {omega}{sub {beta}}. Growth is enhanced by optical guiding in the ion channel, which acts as dielectric waveguide, with fiber parameter V {approximately} 2 (I/I{sub A}){sup 1/2}. A 1-D theory for such an ion-channel laser'' is formulated, scaling laws are derived and numerical examples are given. Possible expe… more
Date: January 1990
Creator: Whittum, D. H.; Sessler, A. M. & Dawson, J. M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Laser acceleration and nonlinear beam dynamics

Description: This research contract covers the period April 1990, September 1991. The work to be done under the contract was theoretical research in the areas of nonlinear beam dynamics and laser acceleration. In this final report we will discuss the motivation for this work and the results obtained.
Date: January 1, 1991
Creator: Pellegrini, C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Ion clearing the the XLS-ring

Description: The mechanism of ion capture by the beam, their effects on the beam as well as ways to clear the ions are discussed. Special attention is given to these questions for the SXLS ring. 20 refs., 5 figs., 4 tabs.
Date: January 1, 1990
Creator: Bozoki, E.S. & Halama, H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Problems of the compensation methods for the spin depolarizing resonances in the strong focusing synchrotron

Description: The achievement of a high energy polarized proton beam requires the reduction of depolarization during acceleration. This depolarization will occur at spin resonances where the spin precession frequency equals that of a horizontal magnetic field component. There are basically two types of first order depolarizing resonances. One type is an intrinsic resonance which is excited by the periodical focusing structure of the machine. The resonance occurs at {gamma}G=nN {plus minus} {nu}{sub z}, where… more
Date: May 15, 1990
Creator: Sato, Hikaru (National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan))
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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