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Coherent instability and ion trapping considerations for Aladdin lattices

Description: This paper presents the results of an investigation of the effects of ions and coherent collective instabilities on bunched electron beams circulating in the various Aladdin lattices considered in the Aladdin Upgrade Study. It is aimed particularly at identifying those collective and ion phenomena that may be limiting the performance of the present Aladdin with low energy (100 MeV) injection, at ascertaining which of these phenomena would still remain and limit the performance with a full energy (800 MeV) injector for any correction schemes (either active or passive) to alleviate the performance impact of these phenomena; overview of the behavior at low and high energy (and current), the dependence of this behavior on the rf frequency, and the resulting implications for the upgraded Aladdin operations will emerge in the course of this report. 12 refs., 11 figs., 5 tabs.
Date: May 1, 1985
Creator: Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department

Structural analysis of equilibrium and ohmic heating coil assemblies for the TFTR

Description: The structural adequacy of the equilibrium and ohmic heating coils and their support systems for the TFTR device has been investigated. The capability of the coils to span ribs of the support structure has been established. The support structure has been found to be effective in resisting the magnetic forces in the coils. The bands encircling the outboard coils and the band tensioning devices have been found to perform adequately. The analysis is based on October 1975 conceptual design.
Date: October 1, 1975
Creator: Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department

Stochastic cooling of bunched beams from fluctuation and kinetic theory

Description: A theoretical formalism for stochastic phase-space cooling of bunched beams in storage rings is developed on the dual basis of classical fluctuation theory and kinetic theory of many-body systems in phase-space. The physics is that of a collection of three-dimensional oscillators coupled via retarded nonconservative interactions determined by an electronic feedback loop. At the heart of the formulation is the existence of several disparate time-scales characterizing the cooling process. Both theoretical approaches describe the cooling process in the form of a Fokker-Planck transport equation in phase-space valid up to second order in the strength and first order in the auto-correlation of the cooling signal. With neglect of the collective correlations induced by the feedback loop, identical expressions are obtained in both cases for the coherent damping and Schottky noise diffusion coefficients. These are expressed in terms of Fourier coefficients in a harmonic decomposition in angle of the generalized nonconservative cooling force written in canonical action-angle variables of the particles in six-dimensional phase-space. Comparison of analytic results to a numerical simulation study with 90 pseudo-particles in a model cooling system is presented.
Date: September 1, 1982
Creator: Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department

On storage rings for short wavelength FELs

Description: Significant advances have been made recently in the understanding of FEL physics and the technology of associated systems. We have witnessed experimental successes in the operation of FELs from the far infrared to the visible and near UV. All of the basic physics of FELs, as advanced up to date, in the small and high gain regimes (including exponential growth from noise, optical guiding, etc.) have been proved experimentally in the near or far infrared. These successes motivate us to explore the design of FEL systems at even shorter wavelengths, in the UV, XUV and soft x-ray regions, assuming that the same physics remain valid at these wavelengths. This paper is concerned with issues in the physics and design of storage rings as drivers of short wavelength FELs. 10 refs., 4 figs., 1 tab.
Date: January 1, 1990
Creator: Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department

Simulation of synchrotron motion with rf noise

Description: The theoretical formulation is described that is behind an algorithm for synchrotron phase-space tracking with rf noise and some preliminary simulation results of bunch diffusion under rf noise obtained by actual tracking.
Date: August 1, 1986
Creator: Leemann, B.T.; Forest, E. & Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department

Advances in beam physics and technology: Colliders of the future

Description: Beams may be viewed as directed and focussed flow of energy and information, carried by particles and electromagnetic radiation fields (ie, photons). Often, they interact with each other (eg, in high energy colliders) or with other forms of matter (eg, in fixed targets, sychrotron radiation, neutron scattering, laser chemistry/physics, medical therapy, etc.). The whole art and science of beams revolve around the fundamental quest for, and ultimate implementation of, mechanisms of production, storage, control and observation of beams -- always directed towards studies of the basic structures and processes of the natural world and various practical applications. Tremendous progress has been made in all aspects of beam physics and technology in the last decades -- nonlinear dynamics, superconducting magnets and rf cavities, beam instrumentation and control, novel concepts and collider praradigms, to name a few. We illustrate this progress with a few examples and remark on the emergence of new collider scenarios where some of these progress might come to use -- the Gamma-Gamma Collider, the Muon Collider, laser acceleration, etc. We close with an outline of future oppotunities and outlook.
Date: November 1, 1994
Creator: Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department

Stochastic cooling of bunched beams

Description: Numerical simulation studies are presented for transverse and longitudinal stochastic cooling of bunched particle beams. Radio frequency buckets of various shapes (e.g. rectangular, parabolic well, single sinusoidal waveform) are used to investigate the enhancement of phase space cooling by nonlinearities of synchrotron motion. The connection between the notions of Landau damping for instabilities and mixing for stochastic cooling are discussed. In particular, the need for synchrotron frequency spread for both Landau damping and good mixing is seen to be comparable for bunched beams.
Date: March 1, 1981
Creator: Bisognano, J.J. & Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department

Study of the beam breakup mode in linear induction accelerators for heavy ions

Description: A simple theoretical study and numerical estimate is presented for the transverse amplitude growth of a nonrelativistic heavy ion beam in an induction linac, as envisaged for use in commercial power plants, due to the nonregenerative coherent beam breakup mode. An equivalent electrical circuit has been used to represent the accelerating induction modules. Our calculation shows that for the parameters of interest, the beam breakup amplitude for a heavy ion beam grows extremely slowly in the time scales of interest, to magnitudes insignificant for transport purposes. It is concluded that the coherent beam breakup mode does not pose any serious threat to the stability of a high current (kA) heavy ion beam in an induction linac.
Date: March 1, 1981
Creator: Chattopadhyay, S.; Faltens, A. & Smith, L.
Partner: UNT Libraries Government Documents Department

Calculation of collective effects and beam lifetimes for the LBL (Lawrence Berkeley Laboratory) 1-2 GeV synchrotron radiation source

Description: In designing a third-generation high brightness synchrotron radiation source, attention must be paid to the various collective effects that can influence beam performance. We report on calculations, performed with the code ZAP, of the bunch length, the transverse emittance and the beam lifetime (from both Touschek and gas scattering) for our 1-2 GeV storage ring. In addition, we estimate the growth times for both longitudinal and transverse coupled bunch instabilities. Bunch lengths of about 20 ps should be obtainable and intrabeam scattering emittance growth is small. For a limiting undulator gap of 1 cm and residual gas pressure of 1n Torr, the beam lifetime is about 5 hours in the single-bunch mode; in the multibunch mode, lifetimes in excess of 6 hours are expected. These results indicate that all performance goals for the facility should be achievable.
Date: March 1, 1987
Creator: Chattopadhyay, S. & Zisman, M.S.
Partner: UNT Libraries Government Documents Department

Beam Dynamics Activities and Plans at LBL

Description: On-going beam dynamics studies at LBL are performed in connection with the 1-2 GeV Advanced Light Source (ALS), the SSC, Collider Physics (Novel Power Sources) and Heavy Ion Fusion Accelerator Research (HIFAR). Exploratory activities include generic research on (a) high-brightness, low-emittance storage rings and linacs for the TeV-scale future linear colliders, b{bar b} facilities, etc., (b) beam dynamics and optics of incoherent and coherent undulator radiation, (c) Free Electron Laser Studies, (d) development of a high-brightness laser-driven RF photocathode electron source for the LBL-LLNL-SLAC collaboration on Relativistic Klystrons and (e) new methods of acceleration. The major physics issues being studied in connection with the ALS are the effects of undulators and wigglers on storage ring beam dynamics (nonlinear stability and stable dynamic aperture), short bunch-length collective phenomena and multi-loop high-fidelity orbit and photon beam feedback for stability of the radiation source. In connection with the first issue, detailed nonlinear behavior of the electron beam in presence of insertion devices in an otherwise symmetric low-emittance lattice are being pursued and various compensation schemes are being investigated. We held a workshop on this specialized topic May 17-20, 1988 at LBL, where participants from international laboratories such as Sincrotrone Trieste, KEK, SLAC, BNL, ANL, etc., participated. Contributions will soon be published as proceedings to this workshop. Considerable insight into the physics of short bunches has been gained through a similar workshop last year on the 'Impedance Beyond Cutoff' at LBL, where a realistic picture of the impedance spectrum at high frequencies corresponding to short bunch lengths emerged. The focus at the moment is on the nature of coherent instabilities potentially driven by this high-frequency impedance. Securing a stable photon beam against vibrations and other noise sources simultaneously at several beam lines in a synchrotron radiation source is nontrivial and requires multi-loop orbit feedback ...
Date: July 1, 1988
Creator: Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department

Plasma lens experiments at the final focus test beam

Description: The authors intend to carry out a series of plasma lens experiments at the Final Focus Test Beam facility at SLAC. These experiments will be the first to study the focusing of particle beams by plasma focusing devices in the parameter regime of interest for high energy colliders, and is expected to lead to plasma lens designs capable of unprecedented spot sizes. Plasma focusing of positron beams will be attempted for the first time. They will study the effects of lens aberrations due to various lens imperfections. Several approaches will be applied to create the plasma required including laser ionization and beam induced tunneling ionization of a working gas--the latter which has never been observed before. The compactness of the device should prove to be of interest for applications at the SLC and the next generation linear colliders.
Date: February 1, 1995
Creator: Barletta, W.; Chattopadhyay, S. & Chen, P.
Partner: UNT Libraries Government Documents Department

Photon-Electron Interaction and Condense Beams

Description: We discuss beams of charged particles and radiation from multiple perspectives. These include fundamental acceleration and radiation mechanisms, underlying electron-photon interaction, various classical and quantum phase-space concepts and fluctuational interpretations.
Date: November 1, 1998
Creator: Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department

ZAP user's manual

Description: The use and content of Phase I of the accelerator physics code ZAP, which calculates the performance of a storage ring in terms of the effects of beam intensity dependent phenomena and the limitations they impose. A brief overview is provided of the code and the types of calculations that can be performed with it. The types of calculations available include: single bunch thresholds, single bunch longitudinal parameters and energy scaling tables, longitudinal coupled-bunch instabilities, transverse coupled-bunch instabilities, gas scattering lifetime, free electron laser formulae, intrabeam scattering, Touschek scattering, and ion trapping formulae. Examples of the required inputs and resultant outputs for each of the options are given. The theoretical foundations behind ZAP are summarized, providing the relevant formulations, physical models, and particularly the equations used in the code in evaluating the various effects that are computed. (LEW)
Date: December 1, 1986
Creator: Zisman, M.S.; Chattopadhyay, S. & Bisognano, J.J.
Partner: UNT Libraries Government Documents Department

Physics and design issues of asymmetric storage ring colliders as B-factories

Description: This paper concentrates on generic R D and design issues of asymmetric colliders via a specific example, namely a 9 GeV {times} 3 GeV collider based on PEP at SLAC. An asymmetric e{sup +}-e{sup -} collider at the Y(4s) and with sufficiently high luminosity (10{sup 33}-10{sup 34} cm{sup -2} s{sup -1}) offers the possibility of studying mixing, rare decays, and CP violation in the B{bar B} meson system, as well as beautiful'' tau-charm physics, and has certain qualitative advantages from detection and machine design points of view. These include: the energy constraint; clean environment ({approximately}25% B{sup +}B{sup -}, B{sup 0}{bar B}{sup 0}); large cross section (1 nb); vertex reconstruction (from the time development of space-time separated B and {bar B} decays due to moving center-of-mass); reduced backgrounds; greatest sensitivity to CP violation in B {yields} CP eigenstate; the possibility of using higher collision frequencies, up to 100 MHz, in a head-on colliding mode using magnetic separation. It is estimated that for B {yields} {Psi}K{sub s}, an asymmetric collider has an advantage equivalent to a factor of five in luminosity relative to a symmetric one. There are, however, questions with regard to the physics of the asymmetric beam-beam coulomb interaction that may limit the intrinsic luminosity and the possibility of realizing the small beam pipes necessary to determine the vertices. 16 refs., 2 figs.
Date: August 1, 1989
Creator: Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department

Accelerator physics experiments at Aladdin

Description: The Aladdin accelerator is a 1 GeV synchrotron light source located at the University of Wisconsin. The results of experimental studies of the Aladdin accelerator are described. The primary purpose of the experiments reported was to investigate reported anomalies in the behavior of the linear lattice, particularly in the vertical plane. A second goal was to estimate the ring broadband impedance. Experimental observations and interpretation of the linear properties of the Aladdin ring are described, including the beta function and dispersion measurements. Two experiments are described to measure the ring impedance, the first a measurement of the parasitic mode loss, and the second a measurement of the beam transfer function. Measurements of the longitudinal and transverse emittance at 100 and 200 MeV are described and compared with predictions. 10 refs., 24 figs., 2 tabs. (LEW)
Date: July 1, 1985
Creator: Chattopadhyay, S.; Cornacchia, M.; Jackson, A. & Zisman, M.S.
Partner: UNT Libraries Government Documents Department

Generation of Femtosecond X-Rays by 90 degrees Compton Scattering

Description: We propose Compton scattering of a short pulse visible laser beam by a low energy (but relativistic) electron beam at a right angle for generation of femtosecond x-rays. Simple analysis to determine the qualitative and quantitative characteristics of the x-ray pulse is presented.
Date: December 1, 1992
Creator: Kim, K.-J.; Chattopadhyay, S. & Shank, C.V.
Partner: UNT Libraries Government Documents Department

Study on a test of optical stochastic cooling scheme in a single pass beam line

Description: A feasibility study of an experiment to test the principle of optical stochastic cooling is presented. We propose to build a new beamline in the extraction area of the ALS Booster synchrotron, where we will include a bypass lattice similar to the lattice that could be used in the cooling insertion in a storage ring. Of course, in the single pass beamline we cannot achieve cooling, but we can test all the functions of the bypass lattice that are required to achieve cooling in a storage ring. As it is stated in, there are stringent requirements on the time-of-flight properties of the bypass lattice employed in a cooling scheme. The pathlengths of particle trajectories in the bypass must be fairly insensitive to the standard set of errors that usually affect the performance of storage rings. Namely, it is necessary to preserve all fluctuations in the longitudinal particle density within the beam from the beginning to the end of the bypass lattice with the accuracy of {lambda}/2{pi}, where A is the carrying (optical) wavelength. According to, cooling will completely vanish if a combined effect of all kinds of errors will produce a spread of the pathlengths of particle trajectories larger than {lambda}/2 and the cooling time will almost double if the spread of the pathlengths is {lambda}/2{pi}. At a first glance, {lambda}/2{pi} {approx_equal} 0.1/{mu}m is such a small value that satisfying this accuracy looks nearly impossible. However, simulations show that a carefully designed bypass can meet all the requirements even with rather conservative tolerance to errors.
Date: January 1997
Creator: Chattopadhyay, S.; Kim, C.; Massoletti, D. & Zholents, A.
Partner: UNT Libraries Government Documents Department

Halo particle confinement in the VLHC using optical stochastic cooling

Description: Beam halo particles following the extreme trajectories near the physical aperture limit radiate Smith-Purcell radiation when moving over a diffraction grating. This grating can be used as a pick-up and a kicker for optical stochastic cooling of the halo particles. In this application cooling would have the effect of slowing down the halo particle diffusion onto the aperture. Cooling efficiency would quickly diminish with the distance from the aperture and would only affect the halo particles. A preliminary analysis of this system is considered.
Date: June 1, 2000
Creator: Zholents, Alexander; Barletta, W.; Chattopadhyay, S. & Zolotorev, M.
Partner: UNT Libraries Government Documents Department

The LBL advanced light source

Description: The LBL Advanced Light Source (ALS) will be a third generation synchrotron radiation facility. It is based on a low emittance 1--2 GeV electron storage ring (natural radial emittance <10 nm-rad), optimized to produce extremely bright beams of electromagnetic radiation (in the energy range from a few eV to around one keV) from insertion devices known as undulators. The storage ring is fed from an injection system consisting of a 50 MeV linac and a 1.5 GeV, 1 Hz, booster synchrotron, which can fill the ring to its normal operating current (400 mA, multibunch, or 7.6 mA, single bunch) in a few minutes. As well as high brightness (which is a consequence of the very small electron beam emittance in the storage ring), the design emphasizes: picosecond timestructure, laserlike coherence properties, narrow bandwidth, and long beam lifetimes. The more familiar continuous synchrotron radiation spectrum will be available from bending magnets and from wiggler magnets. This paper gives a general description of the ALS and discusses some of the significant design issues associated with the low emittance storage ring that is required for this new facility. 7 refs., 6 figs., 2 tabs.
Date: June 1, 1988
Creator: Jackson, A.; Chattopadhyay, S.; Keller, R.; Kim, C.; Nishimura, H.; Selph, F. et al.
Partner: UNT Libraries Government Documents Department

An asymmetric B-meson factory at PEP

Description: A preliminary design for a B-factory has been made using asymmetric collisions between positrons in the PEP storage ring and electrons in a new, log-energy ring. The design utilizes small-aperture, permanent-magnet quadrupoles close to the interaction point (IP). Optimization of optical and beam parameters at the IP will be discussed, as well as the lattice design of the interaction region and of the rings. 7 refs., 3 figs., 2 tabs.
Date: March 1, 1989
Creator: Garren, A.; Chattopadhyay, S.; Chin, Y.; Oddone, P.; Zisman, M.S.; Donald, M. et al.
Partner: UNT Libraries Government Documents Department

Experiment and simulation of hole-coupled resonator modes with a CW HeNe laser

Description: The Infrared Free Electron Laser (IRFEL) for the proposed Chemical Dynamics Laboratory at Lawrence Berkeley Laboratory will operate from 3 - 50 [mu]m and use all-metal optics. This choice of optics allows for broad tuning and has excellent power-handling capabilities. A hole-coupling approach for the optical resonator was adopted after extensive computer simulations verified that it fully met the design requirements. To bench-test the simulations we have carried out a scaled cavity experiment utilizing a visible (632.8 nm) continuous wave (CW) HeNe laser. Two cases have been studied: (a) a Gaussian near-concentric symmetric resonator and (b) a hole-coupled resonator with degenerate higher order modes. The simple geometry of the former case allows for a direct comparison with analytical theory and is useful for bench marking the diagnostic equipment. Since mode degeneracy should be avoided for good operation of an FEL, gaining an understanding of the latter case is important. Furthermore, it provides a good test case for evaluating the code performance. After discussing the theoretical model used in the simulations, we describe the cavity parameters and the experimental set-up. We proceed by comparing, for both case (a) and (b), the experimental results with theoretical predictions and simulations. This is followed by the summary and conclusions of these experiments.
Date: August 1, 1992
Creator: Leemans, W.P.; Xie, M.; Edighoffer, J.A.; Wallace, E.; Kim, K.J. & Chattopadhyay, S.
Partner: UNT Libraries Government Documents Department