WorldWideScience

Sample records for bunch effects model

  1. Space Charge Effects in Bunch Shape Monitors

    CERN Document Server

    Feschenko, A V

    2000-01-01

    The operation and parameters of Bunch Shape Monitors using coherent transformation of time structure of an analyzed beam into a spatial one of low energy secondary electrons emitted from a wire target is influenced by the characteristics of a beam under study. The electromagnetic field of a bunch disturbs the trajectories of secondary electrons, thus resulting in a degradation of phase resolution and in errors of phase reading. Another effect is the perturbation of the target potential due to the current in the wire induced by a bunch as well as due to current compensating emission of the secondary electrons. The methods, the models and the results of simulations are presented.

  2. Space Charge Effects in Bunch Shape Monitors

    Science.gov (United States)

    Feschenko, Alexander

    The operation and parameters of Bunch Shape Monitors using coherent transformation of time structure of an analyzed beam into a spatial one of low energy secondary electrons emitted from a wire target is influenced by the characteristics of a beam under study. The electromagnetic field of a bunch disturbs the trajectories of secondary electrons, thus resulting in a degradation of phase resolution and in errors of phase reading. Another effect is the perturbation of the target potential due to the current in the wire induced by a bunch as well as due to current compensating emission of the secondary electrons. The methods, the models and the results of simulations are presented.

  3. Effects of PACMAN bunches in the LHC

    CERN Document Server

    Herr, Werner

    1996-01-01

    The maximum achievable luminosity in the LHC is mainly limited by beam-beam effects. The large number of bunches and their head-on and long range interactions determine the maximum allowable bunch intensity. Furthermore, the arrangement of bunches in the LHC ring imply further complications: the beam-beam effects on a given particle depend on its bunch position in the LHC bunch train and result in the appearance of so-called PACMAN bunches which can have a different dynamic behaviour and life time. The consequences of the existence of such PACMAN bunches are presented and possible procedures to minimize or avoid detrimental effects are discussed.

  4. A semi-analytical modelling of multistage bunch compression with collective effects

    Energy Technology Data Exchange (ETDEWEB)

    Zagorodnov, Igor; Dohlus, Martin

    2010-07-15

    In this paper we introduce an analytical solution (up to the third order) for a multistage bunch compression and acceleration system without collective effects. The solution for the system with collective effects is found by an iterative procedure based on this analytical result. The developed formalism is applied to the FLASH facility at DESY. Analytical estimations of RF tolerances are given. (orig.)

  5. Diffraction effects in the coherent transition radiation bunch length diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Kazakevich, G.; Lebedev, V.; Nagaitsev, S.; /Fermilab

    2007-08-01

    Diffraction effects in the Coherent Transition Radiation (CTR) bunch length diagnostics are considered for the A0 Photoinjector and the New Muon Laboratory (NML) injection module. The effects can cause a noticeable distortion of the measured CTR spectra depending on the experimental setup and the bunch parameters and resulting in errors of the bunch length measurements. Presented calculations show possible systematic errors in the bunch length in measurements based on the CTR spectra at A0 Photo injector and the NML injection module.

  6. Photon anti bunching versus phantom anti bunching?

    International Nuclear Information System (INIS)

    Photon anti bunching defined by two-time correlation functions has hitherto, to our best knowledge, been considered to constitute a unique, well defined effect. We show explicitly that this is by no means the case. We analyze two of the most famous definitions showing that both anti bunching and bunching effects according to one definition can be accompanied by arbitrary photon correlation effects according to another. As an example we discuss a model of parametric frequency conversion. (authors)

  7. Non-linear effects in bunch compressor of TARLA

    Science.gov (United States)

    Yildiz, Hüseyin; Aksoy, Avni; Arikan, Pervin

    2016-03-01

    Transport of a beam through an accelerator beamline is affected by high order and non-linear effects such as space charge, coherent synchrotron radiation, wakefield, etc. These effects damage form of the beam, and they lead particle loss, emittance growth, bunch length variation, beam halo formation, etc. One of the known non-linear effects on low energy machine is space charge effect. In this study we focus on space charge effect for Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) machine which is designed to drive InfraRed Free Electron Laser covering the range of 3-250 µm. Moreover, we discuss second order effects on bunch compressor of TARLA.

  8. Control of synchrotron radiation effects during recirculation with bunch compression

    International Nuclear Information System (INIS)

    Studies of beam quality during recirculation have been extended to an arc providing bunch compression with positive momentum compaction. It controls both incoherent and coherent synchrotron radiation (ISR and CSR) using methods including optics balance and generates little microbunching gain. We detail the dynamical basis for the design, discuss the design process, give an example, and provide simulations of ISR and CSR effects. Reference will be made to a complete analysis of microbunching effects.

  9. Control of synchrotron radiation effects during recirculation with bunch compression

    Energy Technology Data Exchange (ETDEWEB)

    Douglas, David [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Benson, Stephen [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Li, Rui [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Roblin, Yves [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Tennant, Christopher [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Krafft, Geoffrey [Old Dominion Univ., Norfolk, VA (United States); Terzic, Balsa [Old Dominion Univ., Norfolk, VA (United States); Tsai, Cheng [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States)

    2015-05-01

    Studies of beam quality during recirculation have been extended to an arc providing bunch compression with positive momentum compaction. It controls both incoherent and coherent synchrotron radiation (ISR and CSR) using methods including optics balance and generates little microbunching gain. We detail the dynamical basis for the design, discuss the design process, give an example, and provide simulations of ISR and CSR effects. Reference will be made to a complete analysis of microbunching effects.

  10. Direct Numerical Modeling of E-Cloud Driven Instability of a Bunch Train in the CERN SPS

    CERN Document Server

    Vay, J-L; Furman, M A

    2011-01-01

    The simulation package WARP-POSINST was recently upgraded for handling multiple bunches and modeling concurrently the electron cloud buildup and its effect on the beam, allowing for direct self-consistent simulation of bunch trains generating, and interacting with, electron clouds. We have used the WARP-POSINST package on massively parallel supercomputers to study the buildup and interaction of electron clouds with a proton bunch train in the CERN SPS accelerator. Results suggest that a positive feedback mechanism exists between the electron buildup and the e-cloud driven transverse instability, leading to a net increase in predicted electron density.

  11. Effect of plasma inhomogeneity on plasma wakefield acceleration driven by long bunches

    Energy Technology Data Exchange (ETDEWEB)

    Lotov, K. V. [Budker Institute of Nuclear Physics SB RAS, 630090 Novosibirsk, Russia and Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Pukhov, A. [Institut fuer Theoretische Physik I, Heinrich-Heine-Universitaet Duesseldorf, 40225 Duesseldorf (Germany); Caldwell, A. [Max-Planck-Institut fuer Physik, 80805 Muenchen (Germany)

    2013-01-15

    Effects of plasma inhomogeneity on self-modulating proton bunches and accelerated electrons were studied numerically. The main effect is the change of the wakefield wavelength which results in phase shifts and loss of accelerated particles. This effect imposes severe constraints on density uniformity in plasma wakefield accelerators driven by long particle bunches. The transverse two stream instability that transforms the long bunch into a train of micro-bunches is less sensitive to density inhomogeneity than are the accelerated particles. The bunch freely passes through increased density regions and interacts with reduced density regions.

  12. Effect of source/sink ratios on yield components, growth dynamics and structural characteristics of oil palm (Elaeis guineensis) bunches.

    Science.gov (United States)

    Pallas, Benoît; Mialet-Serra, Isabelle; Rouan, Lauriane; Clément-Vidal, Anne; Caliman, Jean-Pierre; Dingkuhn, Michael

    2013-04-01

    Source/sink ratios are known to be one of the main determinants of oil palm growth and development. A long-term experiment (9 years) was conducted in Indonesia on mature oil palms subjected to continuous bunch ablation and partial defoliation treatments to artificially modify source/sink ratios. During the experiment, all harvested bunches were dissected and phenological measurements were carried out to analyse the effect of source/sink ratios on yield components explaining variations in bunch number, the number of fruits per bunch and oil dry weight per fruit. An integrative variable (supply/demand ratio) describing the ratio between the assimilate supply from sources and the growing organ demand for carbohydrate was computed for each plant on a daily basis from observations of the number of developing organs and their sink strength, and of climate variables. Defoliation and bunch ablation affected the bunch number and the fruit number per bunch. Variations in bunch number per month were mainly due to variations in the fraction of aborted inflorescence and in the ratio between female and male inflorescences. Under fluctuating trophic conditions, variations in fruit number per bunch resulted both from changes in fruit-set and in the number of branches (rachillae) per inflorescence. For defoliated plants, the decrease in the number of developing reproductive sinks appeared to be sufficient to maintain fruit weight and oil concentration at the control level, without any major decrease in the concentration of non-structural carbohydrate reserves. Computation of the supply/demand ratio revealed that each yield component had a specific phase of sensitivity to supply/demand ratios during inflorescence development. Establishing quantitative relationships between supply/demand ratios, competition and yield components is the first step towards a functional model for oil palm. PMID:23532136

  13. Exact 1-D Model for Coherent Synchrotron Radiation with Shielding and Bunch Compression

    CERN Document Server

    Mayes, Christopher

    2008-01-01

    Coherent Synchrotron Radiation has been studied effectively using a 1-dimensional model for the charge distribution in the realm of small angle approximations and high energies. Here we use Jefimenko's form of Maxwell's equations, without such approximations, to calculate the exact wake-fields due to this effect in multiple bends and drifts. It has been shown before that the influence of a drift can propagate well into a subsequent bend. We show, for reasonable parameters, that the influence of a previous bend can also propagate well into a subsequent bend, and that this is especially important at the beginning of a bend. Shielding by conducting parallel plates is simulated using the image charge method. We extend the formalism to situations with compressing and decompressing distributions, and conclude that simpler approximations to bunch compression usually overestimates the effect. Additionally, an exact formula for the coherent power radiated by a Gaussian bunch is derived by considering the coherent sync...

  14. Study of coupled-bunch collective effects in the ALS

    International Nuclear Information System (INIS)

    We present an overview of the calculated longitudinal and transverse coupled-bunch (CB) growth rates using the measured RF cavity higher order mode (HOM) impedance for the Advanced Light Source (ALS), a 1.5 GeV electron storage ring for producing synchrotron radiation. We also describe a visual method of representing the effective beam impedance and corresponding growth rates which is especially useful for understanding the dependence of growth rate on HOM frequency and Q, for determining the requirements of the CB feedback system, and for interpreting measured beam spectra

  15. Coherent effects of a macro-bunch in an undulator

    CERN Document Server

    Dohlus, M; Limberg, T

    2000-01-01

    The longitudinal radiative force of an electron bunch moving in an undulator has been investigated in [1] assuming an 1D density distribution. To obtain the contribution of pure curvature effects and to avoid singular fields, the 1D linear motion field was subtracted. To relate these results to the 3D case we present analytical and numerical field calculations using the field solver of TRAFIC4. The 1D and 3D cases have been calculated in the transient regime, the steady-state regime and the steady-state regime averaged over one undulator period for the 1 GeV parameter set of the TESLA FEL.

  16. Collective effects for long bunches in dual harmonic RF systems

    Institute of Scientific and Technical Information of China (English)

    AN Shi-Zhong; Klaus Bongardt; Rudolf Maier; TANG Jing-Yu; ZHANG Tian-Jue

    2008-01-01

    The storage of long bunches for large time intervals needs flattened stationary buckets with a large bucket height.Collective effects from the space charge and resistive impedance are studied by looking at the incoherent particle motion for the matched and mismatched bunches.Increasing the RF amplitude with particle number provides r.m.s wise matching for modest intensities.The incoherent motion of large amplitude particles depends on the details of the RF system.The resulting debunching process is a combination of the too small full RF acceptance together with the mismatch,enhanced by the collective effects.Irregular single particle motion is not associated with the coherent dipole instability.For the stationary phase space distribution of the Hofmann-Pedersen approach and for the dual harmonic RF system,stability limits are presented,which are too low if using realistic input distributions.For single and dual harmonic RF system with d=0.31,the tracking results are shown for intensities,by a factor of 3 above the threshold values.Small resistive impedances lead to coherent oscillations around the equilibrium phase value,as energy loss by resistive impedance is compensated by the energy gain of the RF system.

  17. Theoretical studies of higher order effect and coherent synchrotron radiation in magnetic femtosecond electron bunch compressor

    International Nuclear Information System (INIS)

    A new S-band femtosecond electron linear accelerator, which was constructed with a laser driven photocathode RF gun, a linear accelerator (linac) and a magnetic bunch compressor, was developed in Osaka University for the study of radiation-induced ultrafast physical and chemical reactions on femtosecond time scale. In last year, an electron bunch with bunch length of 98 fs in rms were generated. For the realization of the pulse radiolysis with higher time resolution, a more short electron bunch is required. However, the higher order effect and coherent synchrotron radiation in magnetic electron bunch compressor should be considered and reduced for the generation of the such electron bunch. In this paper these effects in the compressor by TRANSPORT code and PARMELA code. (author)

  18. Theoretical analysis and simulation of the influence of self-bunching effects and longitudinal space charge effects on the propagation of keV electron bunch produced by a novel S-band Micro-Pulse electron Gun

    Directory of Open Access Journals (Sweden)

    Jifei Zhao

    2016-06-01

    Full Text Available As an important electron source, Micro-Pulse electron Gun (MPG which is qualified for producing high average current, short pulse, low emittance electron bunches steadily holds promise to use as an electron source of Coherent Smith-Purcell Radiation (CSPR, Free Electron Laser (FEL. The stable output of S-band MPG has been achieved in many labs. To establish reliable foundation for the future application of it, the propagation of picosecond electron bunch produced by MPG should be studied in detail. In this article, the MPG which was working on the rising stage of total effective Secondary Electron Yield (SEY curve was introduced. The self-bunching mechanism was discussed in depth both in the multipacting amplifying state and the steady working state. The bunch length broadening induced by the longitudinal space-charge (SC effects was investigated by different theoretical models in different regions. The 2D PIC codes MAGIC and beam dynamic codes TraceWin simulations were also performed in the propagation. The result shows an excellent agreement between the simulation and the theoretical analysis for bunch length evolution.

  19. Theoretical analysis and simulation of the influence of self-bunching effects and longitudinal space charge effects on the propagation of keV electron bunch produced by a novel S-band Micro-Pulse electron Gun

    Science.gov (United States)

    Zhao, Jifei; Lu, Xiangyang; Zhou, Kui; Yang, Ziqin; Yang, Deyu; Luo, Xing; Tan, Weiwei; Yang, Yujia

    2016-06-01

    As an important electron source, Micro-Pulse electron Gun (MPG) which is qualified for producing high average current, short pulse, low emittance electron bunches steadily holds promise to use as an electron source of Coherent Smith-Purcell Radiation (CSPR), Free Electron Laser (FEL). The stable output of S-band MPG has been achieved in many labs. To establish reliable foundation for the future application of it, the propagation of picosecond electron bunch produced by MPG should be studied in detail. In this article, the MPG which was working on the rising stage of total effective Secondary Electron Yield (SEY) curve was introduced. The self-bunching mechanism was discussed in depth both in the multipacting amplifying state and the steady working state. The bunch length broadening induced by the longitudinal space-charge (SC) effects was investigated by different theoretical models in different regions. The 2D PIC codes MAGIC and beam dynamic codes TraceWin simulations were also performed in the propagation. The result shows an excellent agreement between the simulation and the theoretical analysis for bunch length evolution.

  20. Incoherent beam-beam effect---The relationship between tune-shift, bunch length and dynamic aperture

    International Nuclear Information System (INIS)

    Simulation studies of the influence of long bunches on the beam-beam effect in particle colliders suggest that, despite the risk from synchro-betatron resonances, the attainable luminosity may be greater than that obtained for short bunches

  1. Space-charge effects in ultra-high current electron bunches generated by laser-plasma accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Grinner, F. J.; Schroeder, C. B.; Maier, A. R.; Becker, S.; Mikhailova, J. M.

    2009-02-11

    Recent advances in laser-plasma accelerators, including the generation of GeV-scale electron bunches, enable applications such as driving a compact free-electron-laser (FEL). Significant reduction in size of the FEL is facilitated by the expected ultra-high peak beam currents (10-100 kA) generated in laser-plasma accelerators. At low electron energies such peak currents are expected to cause space-charge effects such as bunch expansion and induced energy variations along the bunch, potentially hindering the FEL process. In this paper we discuss a self-consistent approach to modeling space-charge effects for the regime of laser-plasma-accelerated ultra-compact electron bunches at low or moderate energies. Analytical treatments are considered as well as point-to-point particle simulations, including the beam transport from the laser-plasma accelerator through focusing devices and the undulator. In contradiction to non-self-consistent analyses (i.e., neglecting bunch evolution), which predict a linearly growing energy chirp, we have found the energy chirp reaches a maximum and decreases thereafter. The impact of the space-charge induced chirp on FEL performance is discussed and possible solutions are presented.

  2. Direct Numerical Modeling of E-Cloud Driven Instability of a Bunch Train in the CERN SPS

    International Nuclear Information System (INIS)

    The simulation package WARP-POSINST was recently upgraded for handling multiple bunches and modeling concurrently the electron cloud buildup and its effect on the beam, allowing for direct self-consistent simulation of bunch trains generating, and interacting with, electron clouds. We have used the WARP-POSINST package on massively parallel supercomputers to study the buildup and interaction of electron clouds with a proton bunch train in the CERN SPS accelerator. Results suggest that a positive feedback mechanism exists between the electron buildup and the e-cloud driven transverse instability, leading to a net increase in predicted electron density. Electron clouds have been shown to trigger fast growing instabilities on proton beams circulating in the SPS and other accelerators. So far, simulations of electron cloud buildup and their effects on beam dynamics have been performed separately. This is a consequence of the large computational cost of the combined calculation due to large space and time scale disparities between the two processes. We have presented the latest improvements of the simulation package WARP-POSINST for the simulation of self-consistent ecloud effects, including mesh refinement, and generation of electrons from gas ionization and impact at the pipe walls. We also presented simulations of two consecutive bunches interacting with electrons clouds in the SPS, which included generation of secondary electrons. The distribution of electrons in front of the first beam was initialized from a dump taken from a preceding buildup calculation using the POSINST code. In this paper, we present an extension of this work where one full batch of 72 bunches is simulated in the SPS, including the entire buildup calculation and the self-consistent interaction between the bunches and the electrons.

  3. Self-Consistant Numerical Modeling of E-Cloud Driven Instability of a Bunch Train in the CERN SPS

    International Nuclear Information System (INIS)

    The simulation package WARP-POSINST was recently upgraded for handling multiple bunches and modeling concurrently the electron cloud buildup and its effect on the beam, allowing for direct self-consistent simulation of bunch trains generating, and interacting with, electron clouds. We have used the WARP-POSINST package on massively parallel supercomputers to study the growth rate and frequency patterns in space-time of the electron cloud driven transverse instability for a proton bunch train in the CERN SPS accelerator. Results suggest that a positive feedback mechanism exists between the electron buildup and the e-cloud driven transverse instability, leading to a net increase in predicted electron density. Comparisons to selected experimental data are also given. Electron clouds have been shown to trigger fast growing instabilities on proton beams circulating in the SPS and other accelerators. So far, simulations of electron cloud buildup and their effects on beam dynamics have been performed separately. This is a consequence of the large computational cost of the combined calculation due to large space and time scale disparities between the two processes. We have presented the latest improvements of the simulation package WARP-POSINST for the simulation of self-consistent ecloud effects, including mesh refinement, and generation of electrons from gas ionization and impact at the pipe walls. We also presented simulations of two consecutive bunches interacting with electrons clouds in the SPS, which included generation of secondary electrons. The distribution of electrons in front of the first beam was initialized from a dump taken from a preceding buildup calculation using the POSINST code. In this paper, we present an extension of this work where one full batch of 72 bunches is simulated in the SPS, including the entire buildup calculation and the self-consistent interaction between the bunches and the electrons. Comparisons to experimental data are also given.

  4. Direct Numerical Modeling of E-Cloud Driven Instability of a Bunch Train in the CERN SPS

    Energy Technology Data Exchange (ETDEWEB)

    Vay, J-L.; Furman, M.A.; Venturini, M.

    2011-03-01

    The simulation package WARP-POSINST was recently upgraded for handling multiple bunches and modeling concurrently the electron cloud buildup and its effect on the beam, allowing for direct self-consistent simulation of bunch trains generating, and interacting with, electron clouds. We have used the WARP-POSINST package on massively parallel supercomputers to study the buildup and interaction of electron clouds with a proton bunch train in the CERN SPS accelerator. Results suggest that a positive feedback mechanism exists between the electron buildup and the e-cloud driven transverse instability, leading to a net increase in predicted electron density. Electron clouds have been shown to trigger fast growing instabilities on proton beams circulating in the SPS and other accelerators. So far, simulations of electron cloud buildup and their effects on beam dynamics have been performed separately. This is a consequence of the large computational cost of the combined calculation due to large space and time scale disparities between the two processes. We have presented the latest improvements of the simulation package WARP-POSINST for the simulation of self-consistent ecloud effects, including mesh refinement, and generation of electrons from gas ionization and impact at the pipe walls. We also presented simulations of two consecutive bunches interacting with electrons clouds in the SPS, which included generation of secondary electrons. The distribution of electrons in front of the first beam was initialized from a dump taken from a preceding buildup calculation using the POSINST code. In this paper, we present an extension of this work where one full batch of 72 bunches is simulated in the SPS, including the entire buildup calculation and the self-consistent interaction between the bunches and the electrons.

  5. Self-Consistant Numerical Modeling of E-Cloud Driven Instability of a Bunch Train in the CERN SPS

    Energy Technology Data Exchange (ETDEWEB)

    Vay, J-L.; Furman, M.A.; Secondo, R.; Venturini, M.; Fox, J.D.; Rivetta, C.H,

    2010-09-01

    The simulation package WARP-POSINST was recently upgraded for handling multiple bunches and modeling concurrently the electron cloud buildup and its effect on the beam, allowing for direct self-consistent simulation of bunch trains generating, and interacting with, electron clouds. We have used the WARP-POSINST package on massively parallel supercomputers to study the growth rate and frequency patterns in space-time of the electron cloud driven transverse instability for a proton bunch train in the CERN SPS accelerator. Results suggest that a positive feedback mechanism exists between the electron buildup and the e-cloud driven transverse instability, leading to a net increase in predicted electron density. Comparisons to selected experimental data are also given. Electron clouds have been shown to trigger fast growing instabilities on proton beams circulating in the SPS and other accelerators. So far, simulations of electron cloud buildup and their effects on beam dynamics have been performed separately. This is a consequence of the large computational cost of the combined calculation due to large space and time scale disparities between the two processes. We have presented the latest improvements of the simulation package WARP-POSINST for the simulation of self-consistent ecloud effects, including mesh refinement, and generation of electrons from gas ionization and impact at the pipe walls. We also presented simulations of two consecutive bunches interacting with electrons clouds in the SPS, which included generation of secondary electrons. The distribution of electrons in front of the first beam was initialized from a dump taken from a preceding buildup calculation using the POSINST code. In this paper, we present an extension of this work where one full batch of 72 bunches is simulated in the SPS, including the entire buildup calculation and the self-consistent interaction between the bunches and the electrons. Comparisons to experimental data are also given.

  6. Micromechanical modelling of oil palm empty fruit bunch fibres containing silica bodies.

    Science.gov (United States)

    Omar, Farah Nadia; Hanipah, Suhaiza Hanim; Xiang, Loo Yu; Mohammed, Mohd Afandi P; Baharuddin, Azhari Samsu; Abdullah, Jaafar

    2016-09-01

    Experimental and numerical investigation was conducted to study the micromechanics of oil palm empty fruit bunch fibres containing silica bodies. The finite viscoelastic-plastic material model called Parallel Rheological Network model was proposed, that fitted well with cyclic and stress relaxation tensile tests of the fibres. Representative volume element and microstructure models were developed using finite element method, where the models information was obtained from microscopy and X-ray micro-tomography analyses. Simulation results showed that difference of the fibres model with silica bodies and those without ones is larger under shear than compression and tension. However, in comparison to geometrical effect (i.e. silica bodies), it is suggested that ultrastructure components of the fibres (modelled using finite viscoelastic-plastic model) is responsible for the complex mechanical behaviour of oil palm fibres. This can be due to cellulose, hemicellulose and lignin components and the interface behaviour, as reported on other lignocellulosic materials. PMID:27183430

  7. Avalanche electron bunching in a Corbino disk in the quantum Hall effect breakdown regime

    Science.gov (United States)

    Chida, Kensaku; Hata, Tokuro; Arakawa, Tomonori; Matsuo, Sadashige; Nishihara, Yoshitaka; Tanaka, Takahiro; Ono, Teruo; Kobayashi, Kensuke

    2014-06-01

    We have measured the current noise in a device with Corbino geometry to investigate the dynamics of electrons in the breakdown regime of the integer quantum Hall effect (QHE). In the breakdown regime, the Fano factor of the current noise exceeds 103, which indicates the presence of electron bunching. As super-Poissonian current noise is observed only in the breakdown regime, the bunching effect is related to the QHE breakdown. These observations support a QHE breakdown mechanism that involves an electron avalanche.

  8. Effects of diffraction and target finite size on coherent transition radiation spectra in bunch length measurements

    International Nuclear Information System (INIS)

    Effects of diffraction and the size of the target on TR in the context of TR-based bunch length measurements are studied on the basis of Kirchhoff diffraction theory. Spectra of TR from the finite-size target for several schemes of measurements are calculated in the far-infrared region showing strong distortion at low frequencies. Influence of the effect on the accuracy of bunch length measurements is estimated

  9. Klystron beam bunching

    International Nuclear Information System (INIS)

    A detailed description of electron-beam bunching phenomena in klystrons is presented. Beam harmonic current is defined, both space-charge and ballistic bunching are analyzed, Ramo's theorem is used to describe how a bunched beam drives a cavity, and a general cavity model including external coupling is provided. (author)

  10. Sub-fs electron bunch generation with sub-10-fs bunch arrival-time jitter via bunch slicing in a magnetic chicane

    Science.gov (United States)

    Zhu, J.; Assmann, R. W.; Dohlus, M.; Dorda, U.; Marchetti, B.

    2016-05-01

    The generation of ultrashort electron bunches with ultrasmall bunch arrival-time jitter is of vital importance for laser-plasma wakefield acceleration with external injection. We study the production of 100-MeV electron bunches with bunch durations of subfemtosecond (fs) and bunch arrival-time jitters of less than 10 fs, in an S-band photoinjector by using a weak magnetic chicane with a slit collimator. The beam dynamics inside the chicane is simulated by using two codes with different self-force models. The first code separates the self-force into a three-dimensional (3D) quasistatic space-charge model and a one-dimensional coherent synchrotron radiation (CSR) model, while the other one starts from the first principle with a so-called 3D sub-bunch method. The simulations indicate that the CSR effect dominates the horizontal emittance growth and the 1D CSR model underestimates the final bunch duration and emittance because of the very large transverse-to-longitudinal aspect ratio of the sub-fs bunch. Particularly, the CSR effect is also strongly affected by the vertical bunch size. Due to the coupling between the horizontal and longitudinal phase spaces, the bunch duration at the entrance of the last dipole magnet of the chicane is still significantly longer than that at the exit of the chicane, which considerably mitigates the impact of space charge and CSR effects on the beam quality. Exploiting this effect, a bunch charge of up to 4.8 pC in a sub-fs bunch could be simulated. In addition, we analytically and numerically investigate the impact of different jitter sources on the bunch arrival-time jitter downstream of the chicane, and define the tolerance budgets assuming realistic values of the stability of the linac for different bunch charges and compression schemes.

  11. The Effective CSR Forces on an Energy-Chirped Bunch under Magnetic Compression

    International Nuclear Information System (INIS)

    Following our earlier formulation of the coherent synchrotron radiation (CSR) effect on bunch dynamics in magnetic bends, here we investigate the behavior of the effective CSR forces for an energy-chirped Gaussian bunch in the bending plane around full compression, with special care being taken in the incorporation of the retardation relation. Our results show clearly a delayed response of the CSR forces to the compression or lengthening of the bunch length. In addition, around full compression, our results reveal sensitivity of the effective CSR forces on the particles' transverse position, as a consequence of the geometry of particle interaction and retardation in this regime. These results can serve as benchmarks to the numerical simulation of the CSR effects

  12. Method and apparatus for control of coherent synchrotron radiation effects during recirculation with bunch compression

    Science.gov (United States)

    Douglas, David R; Tennant, Christopher

    2015-11-10

    A modulated-bending recirculating system that avoids CSR-driven breakdown in emittance compensation by redistributing the bending along the beamline. The modulated-bending recirculating system includes a) larger angles of bending in initial FODO cells, thereby enhancing the impact of CSR early on in the beam line while the bunch is long, and 2) a decreased bending angle in the final FODO cells, reducing the effect of CSR while the bunch is short. The invention describes a method for controlling the effects of CSR during recirculation and bunch compression including a) correcting chromatic aberrations, b) correcting lattice and CSR-induced curvature in the longitudinal phase space by compensating T.sub.566, and c) using lattice perturbations to compensate obvious linear correlations x-dp/p and x'-dp/p.

  13. Method and apparatus for control of coherent synchrotron radiation effects during recirculation with bunch compression

    Energy Technology Data Exchange (ETDEWEB)

    Douglas, David R; Tennant, Christopher

    2015-11-10

    A modulated-bending recirculating system that avoids CSR-driven breakdown in emittance compensation by redistributing the bending along the beamline. The modulated-bending recirculating system includes a) larger angles of bending in initial FODO cells, thereby enhancing the impact of CSR early on in the beam line while the bunch is long, and 2) a decreased bending angle in the final FODO cells, reducing the effect of CSR while the bunch is short. The invention describes a method for controlling the effects of CSR during recirculation and bunch compression including a) correcting chromatic aberrations, b) correcting lattice and CSR-induced curvature in the longitudinal phase space by compensating T.sub.566, and c) using lattice perturbations to compensate obvious linear correlations x-dp/p and x'-dp/p.

  14. Proceedings of the impedance and bunch instability workshop

    Energy Technology Data Exchange (ETDEWEB)

    1990-04-01

    This report discusses the following topics: impedance and bunch lengthening; single bunch stability in the ESRF; a longitudinal mode-coupling instability model for bunch lengthening; high-frequency behavior of longitudinal coupling impedance; beam-induced energy spreads at beam-pipe transitions; on the calculation of wake functions using MAFIA-T3 code; preliminary measurements of the bunch length and the impedance of LEP; measurements and simulations of collective effects in the CERN SPS; bunch lengthening in the SLC damping rings; and status of impedance measurements for the spring-8 storage ring.

  15. Proceedings of the impedance and bunch instability workshop

    International Nuclear Information System (INIS)

    This report discusses the following topics: impedance and bunch lengthening; single bunch stability in the ESRF; a longitudinal mode-coupling instability model for bunch lengthening; high-frequency behavior of longitudinal coupling impedance; beam-induced energy spreads at beam-pipe transitions; on the calculation of wake functions using MAFIA-T3 code; preliminary measurements of the bunch length and the impedance of LEP; measurements and simulations of collective effects in the CERN SPS; bunch lengthening in the SLC damping rings; and status of impedance measurements for the spring-8 storage ring

  16. Comparison of 1D and 2D CSR Models with Application to the FERMI@ELETTRA Bunch Compressors

    Energy Technology Data Exchange (ETDEWEB)

    Bassi, G.; Ellison, J.A.; Heinemann, K.

    2011-03-28

    We compare our 2D mean field (Vlasov-Maxwell) treatment of coherent synchrotron radiation (CSR) effects with 1D approximations of the CSR force which are commonly implemented in CSR codes. In our model we track particles in 4D phase space and calculate 2D forces [1]. The major cost in our calculation is the computation of the 2D force. To speed up the computation and improve 1D models we also investigate approximations to our exact 2D force. As an application, we present numerical results for the Fermi{at}Elettra first bunch compressor with the configuration described in [1].

  17. Comparison of 1D and 2D CSR Models with Application to the FERMI(at)ELETTRA Bunch Compressors

    International Nuclear Information System (INIS)

    We compare our 2D mean field (Vlasov-Maxwell) treatment of coherent synchrotron radiation (CSR) effects with 1D approximations of the CSR force which are commonly implemented in CSR codes. In our model we track particles in 4D phase space and calculate 2D forces (1). The major cost in our calculation is the computation of the 2D force. To speed up the computation and improve 1D models we also investigate approximations to our exact 2D force. As an application, we present numerical results for the Fermi(at)Elettra first bunch compressor with the configuration described in (1).

  18. Effect of voltage ramping for time-of-flight bunching on light ion beam transport efficiency

    International Nuclear Information System (INIS)

    A multimodular light ion inertial confinement fusion (ICF) system directs 10--30 MJ of ion energy from 10 to 30 intense ion-beam diodes onto a target for implosion. Each beam is focused and transported over a distance of a few meters from the ion diode to the target. This standoff allows for packing the pulsed power generators around the target chamber, for isolation of the diode hardware form the target explosion, and for power compression by time-of-flight (TOF) bunching. The Laboratory Microfusion Facility (LMF) has been proposed for the study of high-gain, high-yield ICF targets. Bunching factors of α= 2--3 are being considered for LMF. The light-ion transport schemes which have been studied most extensively include ballistic transport, and wire-guided transport. Transport efficiency, ηt, has been calculated previously for all three systems as a function of beam microdivergence, diode radius, and focal distance. In those studies a monoenergetic beam was assumed. Work is presently underway to evaluate the effect that voltage ramping for TOF bunching has on ηt for each of the transport schemes. The bunching factor, number of modules, and total ion energy available to drive the target will be varied to establish their effect on ηt. Available results will be presented

  19. Effect of temperature on pyrolysis product of empty fruit bunches

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Aizuddin Abdul; Sulaiman, Fauziah; Abdullah, Nurhayati [School of Physics, Universiti Sains Malaysia, 11800 Minden, Penang (Malaysia)

    2015-04-24

    Pyrolysis of empty fruit bunches (EFB) was performed in a fixed bed reactor equipped with liquid collecting system. Pyrolysis process was conducted by varying the terminal pyrolysis temperature from 300 to 500°C under heating rate of 10°C/min for at least 2 hours. Char yield was obtained highest at 300°C around 55.88 wt%, and started to decrease as temperature increase. The maximum yield of pyrolysis liquid was obtained around 54.75 wt% as pyrolysis temperature reach 450°C. For gas yield percentage, the yield gained as temperature was increased from 300 to 500°C, within the range between 8.44 to 19.32 wt%. The char obtained at 400°C has great potential as an alternative solid fuel, due to its high heating value of 23.37 MJ/kg, low in volatile matter and ash content which are approximately around 40.32 and 11.12 wt%, respectively. The collected pyrolysis liquid within this temperature range found to have high water content of around 16.15 to 18.20 wt%. The high aqueous fraction seemed to cause the pyrolysis liquid to have low HHV which only ranging from 10.81 to 12.94 MJ/kg. These trends of results showed that necessary enhancement should be employ either on the raw biomass or pyrolysis products in order to approach at least the minimum quality of common hydrocarbon solid or liquid fuel. For energy production, both produced bio-char and pyrolysis liquid are considered as sustainable sources of bio-energy since they contained low amounts of nitrogen and sulphur, which are considered as environmental friendly solid and liquid fuel.

  20. Effect of temperature on pyrolysis product of empty fruit bunches

    Science.gov (United States)

    Rahman, Aizuddin Abdul; Sulaiman, Fauziah; Abdullah, Nurhayati

    2015-04-01

    Pyrolysis of empty fruit bunches (EFB) was performed in a fixed bed reactor equipped with liquid collecting system. Pyrolysis process was conducted by varying the terminal pyrolysis temperature from 300 to 500°C under heating rate of 10°C/min for at least 2 hours. Char yield was obtained highest at 300°C around 55.88 wt%, and started to decrease as temperature increase. The maximum yield of pyrolysis liquid was obtained around 54.75 wt% as pyrolysis temperature reach 450°C. For gas yield percentage, the yield gained as temperature was increased from 300 to 500°C, within the range between 8.44 to 19.32 wt%. The char obtained at 400°C has great potential as an alternative solid fuel, due to its high heating value of 23.37 MJ/kg, low in volatile matter and ash content which are approximately around 40.32 and 11.12 wt%, respectively. The collected pyrolysis liquid within this temperature range found to have high water content of around 16.15 to 18.20 wt%. The high aqueous fraction seemed to cause the pyrolysis liquid to have low HHV which only ranging from 10.81 to 12.94 MJ/kg. These trends of results showed that necessary enhancement should be employ either on the raw biomass or pyrolysis products in order to approach at least the minimum quality of common hydrocarbon solid or liquid fuel. For energy production, both produced bio-char and pyrolysis liquid are considered as sustainable sources of bio-energy since they contained low amounts of nitrogen and sulphur, which are considered as environmental friendly solid and liquid fuel.

  1. Effect of temperature on pyrolysis product of empty fruit bunches

    International Nuclear Information System (INIS)

    Pyrolysis of empty fruit bunches (EFB) was performed in a fixed bed reactor equipped with liquid collecting system. Pyrolysis process was conducted by varying the terminal pyrolysis temperature from 300 to 500°C under heating rate of 10°C/min for at least 2 hours. Char yield was obtained highest at 300°C around 55.88 wt%, and started to decrease as temperature increase. The maximum yield of pyrolysis liquid was obtained around 54.75 wt% as pyrolysis temperature reach 450°C. For gas yield percentage, the yield gained as temperature was increased from 300 to 500°C, within the range between 8.44 to 19.32 wt%. The char obtained at 400°C has great potential as an alternative solid fuel, due to its high heating value of 23.37 MJ/kg, low in volatile matter and ash content which are approximately around 40.32 and 11.12 wt%, respectively. The collected pyrolysis liquid within this temperature range found to have high water content of around 16.15 to 18.20 wt%. The high aqueous fraction seemed to cause the pyrolysis liquid to have low HHV which only ranging from 10.81 to 12.94 MJ/kg. These trends of results showed that necessary enhancement should be employ either on the raw biomass or pyrolysis products in order to approach at least the minimum quality of common hydrocarbon solid or liquid fuel. For energy production, both produced bio-char and pyrolysis liquid are considered as sustainable sources of bio-energy since they contained low amounts of nitrogen and sulphur, which are considered as environmental friendly solid and liquid fuel

  2. Mitigation of the electron-cloud effect in the PSR and SNS protonstorage rings by tailoring the bunch profile

    CERN Document Server

    Pivi, M T

    2003-01-01

    For the storage ring of the Spallation Neutron Source (SNS) at Oak Ridge, and for the Proton Storage Ring (PSR) at Los Alamos, both with intense and very long bunches, the electron cloud develops primarily by the mechanism of trailing-edge multipacting. We show, by means of simulations for the PSR, how the resonant nature of this mechanism may be effectively broken by tailoring the longitudinal bunch profile at fixed bunch charge, resulting in a significant decrease in the electron-cloud effect. We briefly discuss the experimental difficulties expected in the implementation of this cure.

  3. E-Cloud Effects on Singe-Bunch Dynamics in the Proposed PS2

    International Nuclear Information System (INIS)

    One of the options considered for future upgrades of the LHC injector complex entails the replacement of the PSwith the PS2, a longer circumference and higher energy synchrotron. Electron cloud effects represent an importantpotential limitation to the achievement of the upgrade goals. We report the results of numerical studies aimingat estimating the e-cloud density thresholds for the occurrence of single bunch instabilities.

  4. E-Cloud Effects on Singe-Bunch Dynamics in the Proposed PS2

    Energy Technology Data Exchange (ETDEWEB)

    Venturini, M.; Furman, M.; Vay, J.-L.

    2010-10-08

    One of the options considered for future upgrades of the LHC injector complex entails the replacement of the PSwith the PS2, a longer circumference and higher energy synchrotron. Electron cloud effects represent an importantpotential limitation to the achievement of the upgrade goals. We report the results of numerical studies aimingat estimating the e-cloud density thresholds for the occurrence of single bunch instabilities.

  5. Increase of emittance by inverse multiple Touschek effect in a single bunch of charged accelerated particles

    International Nuclear Information System (INIS)

    Coulomb scattering of the longitudinal momentum distribution of particles in an accelerated bunch leads to the creation of a transverse emittance which adds to the natural emittance. This process has been calculated for high energy linacs used in high energy e+e- linear colliders. At beam energies of 500 GeV to 1 TeV, it has been found that the effect is weak

  6. E-Cloud Effects on Singe-Bunch Dynamics in the Proposed PS2

    OpenAIRE

    Venturini, M.

    2012-01-01

    One of the options considered for future upgrades of the LHC injector complex entails the replacement of the PS with the PS2, a longer circumference and higher energy synchrotron. Electron cloud effects represent an important potential limitation to the achievement of the upgrade goals. We report the results of numerical studies aiming at estimating the e-cloud density thresholds for the occurrence of single bunch instabilities.

  7. EFFECT OF HIGH-PRESSURE STEAM TREATMENT ON ENZYMATIC SACCHARIFICATION OF OIL PALM EMPTY FRUIT BUNCHES

    OpenAIRE

    Azhari Samsu Baharuddin,; Noor Seribainun Hidayah Md Yunos; Nik Anis Nik Mahmud,; Rabitah Zakaria; Khairul Faezah Md. Yunos

    2012-01-01

    The effectiveness of high-pressure steam treatment (HPST) with various treatment temperatures (170, 190, 210, and 230 °C) on the enzymatic hydrolysis yield of oil palm empty fruit bunches (OPEFB) was successfully investigated. Analysis of the compositions of raw and treated OPEFB showed that significant changes occurred after the HPST was performed. Scanning electron microscopy (SEM) analysis showed that the treated OPEFB gave better results in removing the silica bodies as compared to the un...

  8. MODELING HYDROGEN PEROXIDE BLEACHING OF SODA PULP FROM OIL-PALM EMPTY FRUIT BUNCHES

    OpenAIRE

    Ana Ferrer; Antonio Rosal; Cristina Valls; Blanca Roncero; Alejandro Rodriguez

    2011-01-01

    The influence of the variables soda (0.5-3.0%), hydrogen peroxide (1.0-6.0%) and time (1-5 h) in the bleaching of soda pulp of empty fruit bunches (EFB) from oil-palm, on the properties of bleached pulps, was studied. Polynomial and neural fuzzy models reproduced the results of brightness, kappa number, and viscosity of the pulps with errors less than 10%. By the simulation of the bleaching of pulp, using the polynomial and neural fuzzy models, it was possible to find optimal values of operat...

  9. Mathematical Models of Feedback Systems for Control of Intra-Bunch Instabilities Driven by E-Clouds and TMCI

    CERN Document Server

    Rivetta, C H; Mastoridis, T; Pivi, M T F; Turgut, O; Höfle, W; Secondo, R; Vay, J L

    2011-01-01

    The feedback control of intrabunch instabilities driven by E-Clouds or strong head-tail coupling (TMCI) requires sufficient bandwidth to sense the vertical position and drive multiple sections of a nanosecond scale bunch. These requirements impose challenges and limits in the design and implementation of the feedback system. This paper presents models for the feedback subsystems: receiver, processing channel, amplifier and kicker, that take into account their frequency response and limits. These models are included in multiparticle simulation codes (WARP/CMAD/Head-Tail) and reduced mathematical models of the bunch dynamics to evaluate the impact of subsystem limitations in the bunch stabilization and emittance improvement. With this realistic model of the hardware, it is possible to analyze and design the feedback system. This research is crucial to evaluate the performance boundary of the feedback control system due to cost and technological limitations. These models define the impact of spurious perturbatio...

  10. Self Consistent Monte Carlo Method to Study CSR Effects in Bunch Compressors

    International Nuclear Information System (INIS)

    In this paper we report on the results of a self-consistent calculation of CSR effects on a particle bunch moving through the benchmark Zeuthen bunch compressors. The theoretical framework is based on a 4D Vlasov-Maxwell approach including shielding from the vacuum chamber. We calculate the fields in the lab frame, where time is the independent variable, and evolve the phase space density/points in the beam frame, where arc length, s, along a reference orbit, is the independent variable. Some details are given in [2], where we also discuss three approaches, the unperturbed source model (UPS), the self consistent Monte Carlo (SCMC) method and the method of local characteristics. Results for the UPS have been presented for 5 GeV before [3], here we compare them with our new results from the SCMC and study the 500MeV case. Our work using the method of characteristics is in progress. The SCMC algorithm begins by randomly generating an initial ensemble of beam frame phase space points according to a given initial phase space density. The algorithm then reduces to laying out one arc length step. Assume that at arc length s we know the location of the phase space points and the history of the source prior to s. We then (1) create a smooth representation of the lab frame charge and current densities, ρL and JL, (2) calculate the fields at s from the history of ρL and JL, and (3) move the beam frame phase space points according to the beam frame equations of motion. This is then iterated. The UPS calculation is similar except the fields are calculated from a function of s computed a priori from the beam frame equations of motion without the self-fields. The phase space points are then evolved according to the equations of motion with these ''unperturbed'' fields. In the UPS we use a Gaussian initial density which evolves under the linear beam frame equations as a Gaussian. This gives us an analytic formula for the source, which significantly speeds up the field

  11. Gamma Irradiation Effects on Oil Palm (Elaies Guineensis) Pollen Viability, Fruits and Bunch Formations

    International Nuclear Information System (INIS)

    Assessing performance and genetic diversity of the wild material of oil palm is important for understanding genetic structure of natural oil palm populations towards improvement of the crops. This information is important for oil palm breeding programs, and also for continued ex-situ conservation of the germplasm and breeding program in Malaysia. Mutation induction is one of the alternative ways in creating variants for selection in the breeding program. In this study, evaluation on the effect of irradiated pollen towards pollen viability, bunches formation and no. of parthenocarpic fruits were conducted. Series of acute gamma radiation at dose 0, 10, 20, 40, 50, 100, 200, 300, 500, 100 and 2000 Gy were exposed to Elaies guineensis pollen. Increasing level of irradiation higher than 200 Grays (Gy) affects pollen viability based on the 12 consecutive days observation evaluated in situ conditions. Besides, at this level of irradiation (> 200 Gy), the pollen tube formation were disrupted and subsequently unable the pollen to reach the ovule which cause the embryo to aborted and contributed to the formation of parthenocarpic fruits and rotten bunches. These observations suggested that at low levels of irradiation (< 200 Gy) may damage only part of the generative nucleus while maintaining its capacity to fertilise the egg cells and lead to hybridization. (author)

  12. Irradiation effect on chemical components of oil palm empty fruit bunch and palm press fibre

    International Nuclear Information System (INIS)

    Physico-chemical properties of empty fruit bunch (EFB) and palm press fibre (PPF), which are major by-products of the oil palm industries, were studied for upgrading their utilisation as animal feed by radiation-fermentation process. Comparative analyses of raw EFB and PPF from 3 different mills showed significant variations in some of their chemical components. Significant differences were also observed between the chemical components of EFB and PPF samples. The water holding capacities (WHC) of both EFB and PPF suggested their suitability for use as fermentation media. Gamma irradiation of up to 50 kGy have little effect on the components of both EFB and PPF. Irradiation dose of 25 kGy appeared to produce enhancement effect on cellulase hydrolysis of holocellulose and alpha-cellulose of EFB but a retarding effect on hydrolysis of PPF

  13. Time scaling relations for step bunches from models with step-step attractions (B1-type models)

    Science.gov (United States)

    Krasteva, A.; Popova, H.; Akutsu, N.; Tonchev, V.

    2016-03-01

    The step bunching instability is studied in three models of step motion defined in terms of ordinary differential equations (ODE). The source of instability in these models is step-step attraction, it is opposed by step-step repulsion and the developing surface patterns reflect the balance between the two. The first model, TE2, is a generalization of the seminal model of Tersoff et al. (1995). The second one, LW2, is obtained from the model of Liu and Weeks (1998) using the repulsions term to construct the attractions one with retained possibility to change the parameters in the two independently. The third model, MM2, is a minimal one constructed ad hoc and in this article it plays a central role. New scheme for scaling the ODE in vicinal studies is applied towards deciphering the pre-factors in the time-scaling relations. In all these models the patterned surface is self-similar - only one length scale is necessary to describe its evolution (hence B1-type). The bunches form finite angles with the terraces. Integrating numerically the equations for step motion and changing systematically the parameters we obtain the overall dependence of time-scaling exponent β on the power of step-step attractions p as β = 1/(3+p) for MM2 and hypothesize based on restricted set of data that it is β = 1/(5+p) for LW2 and TE2.

  14. Investigation of possible csr induced energy spread effects with the A0 photoinjector bunch compressor

    International Nuclear Information System (INIS)

    The bunch compressor of the A0 Photoinjector at Fermilab was removed this past spring to install a transverse to longitudinal emittance exchange experiment. Prior to its removal questions arose about the possibility of observing the effects of Coherent Synchrotron Radiation on the compressed beam. The energy spread of the beam with and without compression was measured to observe any changes. Various beam charges were used to look for square law effects associated with CSR. No direct observation of CSR in the compressor was attempted because the design of the vacuum chamber did not allow it. In this paper we report the results of these experiments and comparison with simulations using ASTRA and CSRTrack. The results are also compared with analytical approximations

  15. EFFECT OF TRIMETHYLOLPROPANE TRIACRYLATE (TMPTA) ON THE MECHANICAL PROPERTIES OF PALM FIBER EMPTY FRUIT BUNCH AND CELLULOSE FIBER BIOCOMPOSITE

    OpenAIRE

    Khalid, M.; A. Salmiaton; C. T. RATNAM; C. A. LUQMAN

    2008-01-01

    The effect of trimethylolpropane triacrylate (TMPTA) as a coupling agent, on the mechanical and morphological properties of the PP-cellulose (derived from oil palm empty fruit bunch fiber) and PP-oil palm empty fruit bunch fiber (EFBF) biocomposites has been studied. The ratio of PP:cellulose and PP:EFBF is fixed to 70:30 (wt/wt%) while the concentration of the coupling agent is varied from 2.0 to 7.0 wt%. Results reveal that at 2.0 wt% of TMPTA concentration, tensile strength, flexural modul...

  16. Effect of Beamstrahlung on Bunch Length and Emittance in Future Circular e+e- Colliders

    CERN Document Server

    Valdivia Garcia, Marco Alan

    2016-01-01

    In future circular e+e− colliders, beamstrahlung may limit the beam lifetime at high energies, and increase the energy spread and bunch length at low energies. If the dispersion or slope of the dispersion is not zero at the collision point, beamstrahlung will also affect the transverse emittance. In this paper, we first examine the beamstrahlung properties, and show that for the proposed FCC-ee, the radiation is fairly well modelled by the classical formulae describing synchrotron radiation in bending magnets. We then derive a set of equations determining the equilibrium emittances in the presence of a nonzero dispersion at the collision point. An example case from FCC-ee will serve as an illustration.

  17. EFFECT OF HIGH-PRESSURE STEAM TREATMENT ON ENZYMATIC SACCHARIFICATION OF OIL PALM EMPTY FRUIT BUNCHES

    Directory of Open Access Journals (Sweden)

    Azhari Samsu Baharuddin,

    2012-06-01

    Full Text Available The effectiveness of high-pressure steam treatment (HPST with various treatment temperatures (170, 190, 210, and 230 °C on the enzymatic hydrolysis yield of oil palm empty fruit bunches (OPEFB was successfully investigated. Analysis of the compositions of raw and treated OPEFB showed that significant changes occurred after the HPST was performed. Scanning electron microscopy (SEM analysis showed that the treated OPEFB gave better results in removing the silica bodies as compared to the untreated OPEFB. This analysis was in agreement with FTIR results, which revealed a significant decrease in the content of hemicelluloses after HPST. During saccharification, the amount of sugar produced was higher for treated OPEFB than untreated OPEFB. Thus, the results suggest that HPST can be applied as an alternative treatment method for the alteration of OPEFB structure and to enhance of the digestibility of the biomass, therefore improving enzymatic hydrolysis.

  18. MODELING HYDROGEN PEROXIDE BLEACHING OF SODA PULP FROM OIL-PALM EMPTY FRUIT BUNCHES

    Directory of Open Access Journals (Sweden)

    Ana Ferrer

    2011-04-01

    Full Text Available The influence of the variables soda (0.5-3.0%, hydrogen peroxide (1.0-6.0% and time (1-5 h in the bleaching of soda pulp of empty fruit bunches (EFB from oil-palm, on the properties of bleached pulps, was studied. Polynomial and neural fuzzy models reproduced the results of brightness, kappa number, and viscosity of the pulps with errors less than 10%. By the simulation of the bleaching of pulp, using the polynomial and neural fuzzy models, it was possible to find optimal values of operating variables, so that the properties of bleached pulps differed only slightly from their best values and yet it was possible to save chemical reagents, energy, and plant size, operating with lower values of operating variables. Thus, operating with 1.13% soda concentration and 2.25% hydrogen peroxide concentration for 3 hours, a pulp with a brightness of 75.1% (8.1% below the maximum and a viscosity of 740 mL/g (10.4% less than the maximum value, was obtained.

  19. High order limit in bunch compressor

    International Nuclear Information System (INIS)

    This paper studies the high order effect in bunch compressing. There exists the limit of high order effect which is from RF accelerating field and bunch compressor, the bunch length obtained from high order theory is longer than that from linear theory, the initial uniform distribution bunch is easier to compress than the initial Gaussian distribution. Finally, a numerical simulation has been carried out, and the results agree with the theory well. (authors)

  20. CSR Effects in a Bunch Compressor influence of the Beam Frame Transverse Force

    CERN Document Server

    Bassi, G

    2005-01-01

    We study the influence of coherent synchrotron radiation (CSR) on particle bunches traveling on arbitrary planar orbits between parallel conducting plates (shielding) with a Vlasov approach. [1] The fields excited by the bunch are computed in the lab frame using a formula simpler than that based on retarded potentials. The Vlasov equation is solved in the beam frame interaction picture. In recent numerical investigations we solved the Vlasov equation for a bunch compressor using the Liouville-Maxwell approximation (LMA), where the bunch density is evolved under the fields produced by the unperturbed density (subject to external fields only), neglecting the beam frame transverse force. [2] Here we report on the influence of the beam frame transverse force on the equations of motion.

  1. Bunched beam stochastic cooling

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Jie

    1992-09-01

    The scaling laws for bunched-beam stochastic cooling has been derived in terms of the optimum cooling rate and the mixing condition. In the case that particles occupy the entire sinusoidal rf bucket, the optimum cooling rate of the bunched beam is shown to be similar to that predicted from the coasting-beam theory using a beam of the same average density and mixing factor. However, in the case that particles occupy only the center of the bucket, the optimum rate decrease in proportion to the ratio of the bunch area to the bucket area. The cooling efficiency can be significantly improved if the synchrotron side-band spectrum is effectively broadened, e.g. by the transverse tune spread or by using a double rf system.

  2. Bunched beam stochastic cooling

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Jie.

    1992-01-01

    The scaling laws for bunched-beam stochastic cooling has been derived in terms of the optimum cooling rate and the mixing condition. In the case that particles occupy the entire sinusoidal rf bucket, the optimum cooling rate of the bunched beam is shown to be similar to that predicted from the coasting-beam theory using a beam of the same average density and mixing factor. However, in the case that particles occupy only the center of the bucket, the optimum rate decrease in proportion to the ratio of the bunch area to the bucket area. The cooling efficiency can be significantly improved if the synchrotron side-band spectrum is effectively broadened, e.g. by the transverse tune spread or by using a double rf system.

  3. Tristan lattice with a bunched proton beam (TRISTAN lattice model III)

    International Nuclear Information System (INIS)

    A bunched proton beam scheme is investigated for the TRISTAN electron- proton collider. It turns out that there are many advantageous features over the coasting proton beam scheme. The bore radius of the proton storage ring can be much reduced. A luminosity of 4.6 x 1031 cm-2s-1 can be achieved with a proton current of 318 mA and an electron current of 210 mA. The stability of the bunched proton beam is also studied. (author)

  4. Bioactive Compounds Isolated from Lignin of Empty Bunch Palm Fiber and Their Effects on in Vitro Rumen Fermentation

    OpenAIRE

    M. Prayuwidayati; T. C. Sunarti; Sumardi; Subeki; K. G. Wiryawan

    2015-01-01

    The objective of this experiment was to study the effects of bioactive compounds isolated from purified lignin formacell (PLF) of empty bunch palm fiber as natural antimicrobes and their effects on in vitro rumen fermentation. The first experiment was inhibition test of 11 bioactive compounds isolated from PLF, using disc diffusion method against the growth of Escherichia coli, Salmonella typhimurium, and Staphylococcus aureus. Four of the most potential bioactive compounds were then used in ...

  5. Analysis of bunch by bunch oscillations with bunch trains at injection into LHC at 25 ns bunch spacing

    CERN Document Server

    Bartosik, H

    2012-01-01

    An MD on August 26, 2011 was dedicated to injection studies of bunch trains with 25 ns spacing and nominal intensity of approximately 1×10(11) protons per bunch. Due to an electrical glitch, the MD was stopped after two attempts of injecting a train of 48 bunches for beam 2. Both injections were aborted after less than 0.1 s. In particular, the first attempt with transverse damper on was dumped after 1000 turns while the second attempt with transverse damper off was dumped after 500 turns only. In this note, an analysis of the bunch by bunch oscillation data recorded with the post-mortem system from the transverse damper is presented. The presented data clearly shows the presence of instabilities that affect mainly the second half of the batch. This is compatible with what would be expected qualitatively in the presence of the electron cloud effect.

  6. A study of beam-beam effects in hadron colliders with a large number of bunches

    CERN Document Server

    Pieloni, Tatiana; Bay, Aurelio; Rivkin, Leonid

    2008-01-01

    A particle beam is a collection of a large number of charges and represents an electromagnetic potential for other charges, therefore exerting forces on itself and other beams. The control of this so called Beam-Beam Interactions (BBIs) in particle colliders is fundamental to preserve beam stability and achieve the collider maximal luminosity. In the case of the Large Hadron Collider (LHC) at CERN, these forces are experienced as localized periodic distortions when the two beams cross each other in the four experimental areas. The forces are most important for high density beams, i.e. high intensity and small beam sizes. Each LHC beam is composed of 2808 bunches, each containing $10^{11}$ protons and with a transverse size of 16~$\\mu $m at the interaction points. These extreme parameters are the key to obtain high ``luminosity'', i. e. the number of collisions per second needed to study rare physics phenomena. The BBI is therefore often the limiting factor for the luminosity of colliders. Within all BB effect...

  7. Production of cellulose phosphate from oil palm empty fruit bunch: Effect of chemical ratio

    Science.gov (United States)

    Rohaizu, R.; Wanrosli, W. D.

    2015-06-01

    Cellulose phosphate was synthesized from oil palm biomass residue that has the potential to represent a considerable added value product for the oil palm biomass utilization. Cellulose phosphate (CP) is prepared viaa phosphorylation process using the H3PO4/P2O5/Et3PO4/hexanol sequence using oil palm empty fruit bunch microcrystalline cellulose (OPEFB-MCC) as the starting material. Various factors affect its synthesis; one of them which is the subject of this investigation is the orthophosphoric acid (H3PO4) to triethylphosphate(Et3PO4) ratio which have the capability to increase the phosphorus content of CP. It is believed that during this reaction, the esterification of the free hydroxyl groups of the cellulose occurred. The H3PO4/Et3PO4 ratios applied were 0.16, 1.00, and 1.84. The effect of the H3PO4/Et3PO4 ratio on phosphorus content, yield, water swelling and molecular structure of CP are discussed.

  8. The Effect of Pretreatment by using Electron Beam Irradiation on Oil Palm Empty Fruit Bunch

    Directory of Open Access Journals (Sweden)

    A. Kristiani

    2016-04-01

    Full Text Available Oil palm empty fruit bunch (OPEFB is a potential type of lignocellulosic biomass for second-generation bioethanol production. The pretreatment process is an important process in the series of processes to produce bioethanol. This research aims to study the effects of pretreatment process by using electron beam irradiation to OPEFB’s characterization as raw materials for the hydrolysis reaction to produce monomer sugars which will be fermented into ethanol. The untreated and treated OPEFB are characterized in terms of their physical and chemical properties. Analysis results of the compositional analysis by using NREL/TP-510-42618 method show that after pretreatment by using electron beam irradiation, OPEFB's total lignin content is changed little while its cellulose and hemicellulose contents tend to decrease with increasing irradiation dose. X-ray diffraction (XRD analysis shows that there is a decrease of crystallinity compared to untreated OPEFB, except for 200-kGy irradiated OPEFB. The highest decrease of crystallinity was shown by 300-kGy irradiated OPEFB. Further, crystallite sizes of treated OPEFBs are not significantly different from the untreated, except for the 200-kGy irradiated OPEFB. Irradiation pretreatment also increases specific surface area, pore volume, and pore size. The IR spectra analysis show the absorption of cellulose, hemicellulose, and lignin.

  9. Evaluation of a bunch-by-bunch fast feedback system at ANKA

    Energy Technology Data Exchange (ETDEWEB)

    Marsching, Sebastian; Hiller, Nicole; Hofmann, Andre; Huttel, Erhard; Judin, Vitali; Kehrer, Benjamin; Klein, Marit; Mueller, Anke-Susanne; Smale, Nigel [Karlsruhe Institute of Technology, Karlsruhe (Germany)

    2011-07-01

    Multi-bunch instabilities are an important limiting factor in the operation of electron storage rings. Using modern bunch-by-bunch fast-feedback systems, these instabilities can be studied and partly damped, thus pushing accelerator performance beyond limits. At ANKA a bunch-by-bunch fast feedback system is currently evaluated for damping instabilities present during injection as well as during user operation. This talk presents the results of the ongoing work regarding the damping of these instabilities and the investigation of the corresponding multi-bunch effects.

  10. Effect of steam pretreatment on oil palm empty fruit bunch for the production of sugars

    International Nuclear Information System (INIS)

    Lignocellulose into fuel ethanol is the most feasible conversion route strategy in terms of sustainability. Oil palm empty fruit bunch (EFB) generated from palm oil production is a huge source of cellulosic material and represents a cheap renewable feedstock which awaits further commercial exploitation. The purpose of this study was to investigate the feasibility of using steam at 0.28 MPa and 140 °C generated from the palm oil mill boiler as a pretreatment to enhance the digestibility of EFB for sugars production. The effects of steam pretreatment or autohydrolysis on chemical composition changes, polysaccharide conversion, sugar production and morphology alterations of four different types of EFB namely fresh EFB (EFB1), sterilized EFB (EFB2), shredded EFB (EFB3) and ground EFB (EFB4) were evaluated. In this study, the effects of steam pretreatment showed major alterations in the morphology of EFB as observed under the scanning electron microscope. Steam pretreated EFB2 was found to have the highest total conversion of 30% to sugars with 209 g kg−1 EFB. This production was 10.5 fold higher than for EFB1 and 1.6 fold and 1.7 fold higher than EFB3 and EFB4, respectively. The results suggested that pretreatment of EFB by autohydrolysis using steam from the mill boiler could be considered as being a suitable pretreatment process for the production of sugars. These sugars can be utilized as potential substrates for the production of various products such as fuel ethanol. -- Highlights: ► We investigate the feasibility of steam pretreatment to enhance digestibility of EFB. ► Steam pretreatment increased sugars to 3.4 fold and caused major alteration in EFB morphology under SEM. ► Autohydrolysis which does not require the addition of chemicals is an attractive pretreatment approach to EFB.

  11. Effect of Chitosan Binder on Water Absorption of Empty Fruit Bunches Filter Media

    International Nuclear Information System (INIS)

    The potential of chitosan as filter media binder was investigated in this study. Chitosan solution with different concentrations were applied to the empty fruit bunches using two different deposition techniques, namely, spray method and addition method. In this study, a water absorption test was used to study the sorption behaviour of empty fruit bunches filter media. The water absorption study showed that the water uptake for empty fruit bunches filter media without the chitosan binder increases with time, until the water sorption reaches the equilibrium state. It was observed that the water uptake decreased from 23 % to 14 % for the chitosan-filled filter media as compared to binder-less filter media, over the duration of 24 hours. For 1 % chitosan concentration, the water uptake is higher compared to 3 % chitosan-filled filter media. The water absorption is relatively lower for filter media with a higher concentration of chitosan due to the high compatibility achieved at this interfacial region between empty fruit bunches fibres and chitosan. Alkali-treated filter media showed the lowest water uptake compared to diethyl ether, ethanol and hot water pretreatment methods. (author)

  12. Analysis on Achieving a Minimum Bunch Length in LCLS Bunch Compressor One

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yipeng; Huang, Zhirong; Ding, Yuantao; Wu, Juhao; /SLAC

    2011-08-19

    An ultra-short bunch is required by different applications in many aspects. In this paper, the condition to achieve a minimum bunch length at the Linac Coherent Light Source (LCLS) [1] bunch compressor one (BC1) is analyzed analytically and evaluated by simulation. The space charge, wake field and coherent synchrotron radiation (CSR) effects are not discussed here.

  13. Digital bunch-by-bunch transverse feedback system at SSRF

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    In order to suppress multi-bunch couple instabilities caused by transverse impedance, a bunch-by-bunch transverse feedback system based on a FPGA digital processor is commissioned at SSRF storage ring. The RF front end has two COD pre-rejected attenuators for increasing the system arrangement and signal noise ratio, and the 3*RF Local signal comes from the BPM’s sum signal using a FIR filter for avoiding the effect of longitudinal oscillation. The digital processor receives the coupled horizontal and vertical oscillation signals in the base band and transforms the coupled signals to the horizontal and vertical feedback signals with two series double-zeroes FIR filters. A matlab GUI is applied for producing the FIR coefficients when the tune is shifted. The horizontal and vertical Kickers have a special design for increasing the shunt impedance. Then the multi-bunch instabilities are suppressed respectively and the minimum damping time is about 0.4 ms.

  14. Effects of diffraction and screen size on CTR based bunch length measurements

    International Nuclear Information System (INIS)

    Coherent transition radiation (CTR) is now well established as one of basic tools to measure electron bunches on a subpicosecond scale. However, a series of experiments has demonstrated that suppression of CTR spectra at low frequencies, occurring in practice, leads to a great uncertainty in the bunch length, determination. In addition to known sources of suppression, it was recently found (1,2) that the size of a screen used to produce transition radiation (TR) can be a factor strongly affecting the spectrum. In this paper it has been calculated TR spectra emitted by a relativistic electron from a finite-size metallic screen and influenced by diffraction on apertures in environment and collecting optics

  15. The Effects of Several Postharvest Treatments on Shelf Life Quality of Bunch Tomatoes

    Directory of Open Access Journals (Sweden)

    Tuba DİLMAÇÜNAL

    2011-11-01

    Full Text Available Bunch tomatoes (Lycopersicon lycopersicum L. ‘Bandita’ cv. were hand-harvested at red ripe stage. The plants were grown on hanging carrying system with high wire support training in coco peat media in a plastic greenhouse located in Antalya (Turkey. Harvested fruits were divided to four groups for these treatments: (1 control-not treated; (2 tomato wax (Tomato wax is a wax formulated from 99% food grade mineral oil and 1% water; (3Nutrient solution (1% potassium nitrate + 0.5% zinc sulfate + 1% calcium chloride + 0.1% boron + 0.2% copper sulfate + 0.5% ascorbic acid + 0.1% salicylic acid and (4 Herbal oil (Herbal oil is a natural product obtained from hazelnut fruit membrane contains a high level of antioxidant. Bunches, placed in carton boxes, stored at 20°C temperature and 90±5% relative humidity for 16 days. Weight loss of bunches, firmness, respiration rate, ethylene production, colour, soluble solid content, pH, titratable acidity and sensory attributes (external appearance and taste-aroma of fruits and wilting and drying of calyxes of tomatoes were evaluated during storage. Tomato wax treatment was limited the weight loss and preserved firmness better than the others. Tomato wax, nutrient solution and herbal oil treatments were limited the respiration rate. Ethylene production of nutrient solution treated fruits showed the highest value followed by herbal oil, tomato wax and control group. The highest colour change was found in control group. The lowest soluble solid content and the highest level of acidity were found in fruits treated with tomato wax. Control , herbal oil and nutrient solution treatments were lost marketable quality after 8 days of storage. TW treatment gave the best result and provided to store bunch tomatoes at good quality for 12 days.

  16. A bunch-by-bunch beam position monitor based on scope embedded IOC

    International Nuclear Information System (INIS)

    A bunch-by-bunch beam position monitor system, based on a broadband oscilloscope embedded EPICS IOC, has been developed at SSRF to study the beam instabilities driven by the wake-field effects. The horizontal and vertical beam positions of each bunch could be located independently in this system by using the original signals from the button-type pickups on the storage ring. In this article, we report the hardware and software architecture of this system. The bunch-by-bunch data of the storage ring are used to evaluate performance of the system. Dependency of the tune, and the betatron oscillation amplitude of different bunch on the corresponding bunch ID, is also detected. The system is an effective tool for machine-study of SSRF. (authors)

  17. The Effects of Several Postharvest Treatments on Shelf Life Quality of Bunch Tomatoes

    OpenAIRE

    DİLMAÇÜNAL, Tuba; Mehmet Ali KOYUNCU; Aktaş, Hakan; BAYINDIR, Derya

    2011-01-01

    Bunch tomatoes (Lycopersicon lycopersicum L.) ‘Bandita’ cv. were hand-harvested at red ripe stage. The plants were grown on hanging carrying system with high wire support training in coco peat media in a plastic greenhouse located in Antalya (Turkey). Harvested fruits were divided to four groups for these treatments: (1) control-not treated; (2) tomato wax (Tomato wax is a wax formulated from 99% food grade mineral oil and 1% water); (3)Nutrient solution (1% potassium nitrate + 0.5% zinc sulf...

  18. Measurement of short bunches

    International Nuclear Information System (INIS)

    In recent years, there has been increasing interest in short electron bunches for different applications such as short wavelength FELs, linear colliders, and advanced accelerators such as laser or plasma wakefield accelerators. One would like to meet various requirements such as high peak current, low momentum spread, high luminosity, small ratio of bunch length to plasma wavelength, and accurate timing. Meanwhile, recent development and advances in RF photoinjectors and various bunching schemes make it possible to generate very short electron bunches. Measuring the longitudinal profile and monitoring bunch length are critical to understand the bunching process and longitudinal beam dynamics, and to commission and operate such short bunch machines. In this paper, several commonly used measurement techniques for subpicosecond bunches and their relative advantages and disadvantages are discussed. As examples, bunch length related measurements at Jefferson lab are presented. At Jefferson Lab, bunch lengths s short as 84 fs have been systematically measured using a zero-phasing technique. A highly sensitive Coherent Synchrotron Radiation (CSR) detector has been developed to noninvasively monitor bunch length for low charge bunches. Phase transfer function measurements provide a means of correcting RF phase drifts and reproducing RF phases to within a couple of tenths of a degree. The measurement results are in excellent agreement with simulations. A comprehensive bunch length control scheme is presented

  19. Measurement of short bunches

    International Nuclear Information System (INIS)

    In recent years, there has been increasing interest in short electron bunches for different applications such as short wavelength FELs, linear colliders, and advanced accelerators such as laser or plasma wakefield accelerators. One would like to meet various requirements such as high peak current, low momentum spread, high luminosity, small ratio of bunch length to plasma wavelength, and accurate timing. Meanwhile, recent development and advances in RF photoinjectors and various bunching schemes make it possible to generate very short electron bunches. Measuring the longitudinal profile and monitoring bunch length are critical to understand the bunching process and longitudinal beam dynamics, and to commission and operate such short bunch machines. In this paper, several commonly used measurement techniques for subpicosecond bunches and their relative advantages and disadvantages are discussed. As examples, bunch length related measurements at Jefferson Lab are presented. At Jefferson Lab, bunch lengths as short as 84 fs have been systematically measured using a zero-phasing technique. A highly sensitive Coherent Synchrotron Radiation (CSR) detector has been developed to noninvasively monitor bunch length for low charge bunches. Phase transfer function measurements provide a means of correcting RF phase drifts and reproducing RF phases to within a couple of tenths of a degree. The measurement results are in excellent agreement with simulations. A comprehensive bunch length control scheme is presented. (author)

  20. THz radiation as a bunch diagnostic forlaser-wakefield-accelerated electron bunches

    Energy Technology Data Exchange (ETDEWEB)

    van Tilborg, J.; Schroeder, C.B.; Filip, C.V.; Toth, Cs.; Geddes,C.G.R.; Fubiani, G.; Esarey, E.; Leemans, W.P.

    2006-02-15

    Experimental results are reported from two measurementtechniques (semiconductor switching and electro-optic sampling) thatallow temporal characterization of electron bunches produced by alaser-driven plasma-based accelerator. As femtosecond electron bunchesexit the plasma-vacuum interface, coherent transition radiation (at THzfrequencies) is emitted. Measuring the properties of this radiationallows characterization of the electron bunches. Theoretical work on theemission mechanism is represented, including a model that calculates theTHz waveform from a given bunch profile. It is found that the spectrum ofthe THz pulse is coherent up to the 200 mu m thick crystal (ZnTe)detection limit of 4 THz, which corresponds to the production of sub-50fs (root-mean-square) electron bunch structure. The measurementsdemonstrate both the shot-to-shot stability of bunch parameters that arecritical to THz emission (such as total charge and bunch length), as wellas femtosecond synchrotron between bunch, THz pulse, and laserbeam.

  1. EFFECT OF TRIMETHYLOLPROPANE TRIACRYLATE (TMPTA ON THE MECHANICAL PROPERTIES OF PALM FIBER EMPTY FRUIT BUNCH AND CELLULOSE FIBER BIOCOMPOSITE

    Directory of Open Access Journals (Sweden)

    M. KHALID

    2008-08-01

    Full Text Available The effect of trimethylolpropane triacrylate (TMPTA as a coupling agent, on the mechanical and morphological properties of the PP-cellulose (derived from oil palm empty fruit bunch fiber and PP-oil palm empty fruit bunch fiber (EFBF biocomposites has been studied. The ratio of PP:cellulose and PP:EFBF is fixed to 70:30 (wt/wt% while the concentration of the coupling agent is varied from 2.0 to 7.0 wt%. Results reveal that at 2.0 wt% of TMPTA concentration, tensile strength, flexural modulus, impact strength and Rockwell hardness of PP-cellulose biocomposite are significantly improved. The enhancement of mechanical properties in the presence of TMPTA is believed to be attributed to crosslinking of multifunctional monomer with the hydroxyl groups of cellulose resulting in better adhesion and superior PP-cellulose biocomposite properties. However, there are no significant changes observed in the PP-EFBF biocomposite properties upon the addition of TMPTA.

  2. Commissioning of the SPPS Linac Bunch Compressor

    International Nuclear Information System (INIS)

    First results and beam measurements are presented for the recently installed linac bunch compressor chicane. The new bunch compressor produces ultra-short electron bunches for the Sub-Picosecond Photon Source (SPPS) and for test beams such as the E164 Plasma Wakefield experiment. This paper will give an overview of the first experiences with tuning and optimizing the compressor together with a description of the beam diagnostics and beam measurements. These measurements form the basis for further detailed study of emittance growth effects such as CSR and wakefields in a previously unmeasured regime of ultra-short bunch lengths

  3. Electron cloud wakefields in bunch trains

    Science.gov (United States)

    Petrov, F. B.; Boine-Frankenheim, Oliver

    2016-02-01

    Electron cloud is a concern for many modern and future accelerator facilities. There are a number of undesired effects attributed to the presence of electron clouds. Among them are coherent instabilities, emittance growth, cryogenic heat load, synchronous phase shift and pressure rise. In long bunch trains one can observe the emittance growth getting faster along the bunch train. The interaction between the beam and the electron cloud is a two-stream interaction. The prameters of the electron cloud wakefields depend on the beam intensity, beam centroid perturbations, and on the electron density and perturbations. If the electron cloud forgets the bunch centroid perturbation very fast, the buildup itself, via growing density, becomes a way of coupling between the bunches. In the present paper we address how the bunch perturbation shape affects the multi-bunch wakefields under the conditions similar to the CERN LHC and SPS. We study the interplay between the single-bunch and multi-bunch electron cloud wakefields. The effect of the dipole magnetic field on the multi-bunch wakefields is studied.

  4. Electro-optical bunch shape measurements - possible temporal resolution limits

    International Nuclear Information System (INIS)

    Coherent synchrotron radiation arises when the longitudinal electron bunch length is smaller than the wavelength. In storage rings, substructures on the electron bunches (micro-bunching) can lead to strong ''bursting'' of coherent radiation and investigation of such effects requires a measurement of the electron bunch length with sufficient temporal resolution. In linear accelerators, the bunch lengths themselves can be extremely short. This report considers the main electro-optical techniques for bunch length measurements and discusses systematic limitations of the method. Special emphasis is put on possible ways to increase the temporal resolution.

  5. Bunch evolution study in optimization of MeV ultrafast electron diffraction

    CERN Document Server

    Lu, Xianhai; Huang, Wenhui; Tang, Chuanxiang

    2014-01-01

    Megaelectronvolt ultrafast electron diffraction (UED) is a promising detection tool for ultrafast processes. The quality of diffraction image is determined by the transverse evolution of the probe bunch. In this paper, we study the contributing terms of the emittance and space charge effects to the bunch evolution in MeV UED scheme, employing a mean-field model with an ellipsoidal distribution as well as particle tracking simulation. Small transverse dimension of the drive laser is found critical to improve the reciprocal resolution, exploiting both smaller emittance and larger transverse bunch size before the solenoid. The degradation of reciprocal spatial resolution caused by the space charge effects should be carefully controlled.

  6. Bunch lengthening in the Fermilab main ring during storage

    International Nuclear Information System (INIS)

    There are two known current dependent effects which can increase the length of stored bunched beams: (1) a reduction of the potential well of the applied rf focusing system; and (2) induced unstable oscillations of the bunches, which can stabilize at a longer length by the process of Landau damping. In the first case, the current distribution in the bunches, interacting with induced electromagnetic fields in the walls, leaves a wake field which acts back on the bunches. A new equilibrium bunch shape results, different from that due to the applied rf, and this new equilibrium bunch shape will slowly establish itself as the particles within the bunch move on their new trajectories. The second form of bunch instability is the single bunch type. These are characterized by high frequency (i.e. within bunch) oscillations in the microwave region and fast growth rates. The coherent effects are very difficult to observe and such instabilities tend to simulate an incoherent growth in the bunch. An attempt is made to describe the observation of bunch lengthening in the main ring in terms of both potential well distortion and induced microwave fields. It is found that the increase in bunch size is in qualitative agreement with an induced microwave instability if the wall (i.e. chamber discontinuities) couples to beam with a broad resistive impedance in the microwave region of the order of Z/n approximately 75 OMEGA

  7. Effect of Reinforcement Shape and Fiber Treatment on the Mechanical Properties of Oil Palm Empty Fruit Bunch-Polyethylene Composites

    Science.gov (United States)

    Arif, M. F.; Yusoff, P. S. M. M.; Eng, K. K.

    2010-03-01

    High Density Polyethylene (HDPE) composites were fabricated using oil palm empty fruit bunch (EFB) as the reinforcing material. The effect of reinforcement shape on the tensile and flexural properties, that is 5 mm average length of short fiber and 325-400 μm size distribution of particulate filler have been studied. Overall, EFB short fiber-HDPE composites yield higher mechanical properties compared to EFB particulate-HDPE composites. For both types of composites, considerable improvement showed in tensile and flexural modulus. However, the tensile strength decreased with increase in EFB content. Attempts to improve these properties using alkali and two types of silane, namely γ-Methacryloxypropyltrimethoxysilane (MTS) and vinyltriethoxysilane (VTS) were described. It is found that both types of silane enhanced the mechanical properties of composites. MTS showed better tensile strength compared to VTS. However, only marginal improvement obtained from alkali treatments.

  8. Effect of electrolyte concentration on performance of supercapacitor carbon electrode from fibers of oil palm empty fruit bunches

    Science.gov (United States)

    Farma, R.; Deraman, M.; Talib, I. A.; Awitdrus, Omar, R.; Ishak, M. M.; Taer, E.; Basri, N. H.; Dolah, B. N. M.

    2015-04-01

    Fibers of oil palm empty fruit bunches were used to produce self-adhesive carbon grains (SACG). The SACG green monoliths were carbonized in N2 environment at 800°C to produce carbon monoliths (CM) and the CM was CO2 activated at 800°C for 4 hour to produce activated carbon monolith electrodes (ACM). The physical properties of the CMs and ACMs were investigated using X-ray diffraction, field emission scanning electron microscopy and nitrogen adsorption-desorption. ACMs were used as electrode to fabricate symmetry supercapacitor cells and the cells which used H2SO4 electrolyte at 0.5, 1.0 and 1.5 M were investigated using electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic charge-discharge standard techniques. In this paper we report the physical properties of the ACM electrodes and the effect of electrolyte concentration on the electrochemical properties the ACM electrodes.

  9. Effect of Reinforcement Shape and Fiber Treatment on the Mechanical Properties of Oil Palm Empty Fruit Bunch-Polyethylene Composites

    International Nuclear Information System (INIS)

    High Density Polyethylene (HDPE) composites were fabricated using oil palm empty fruit bunch (EFB) as the reinforcing material. The effect of reinforcement shape on the tensile and flexural properties, that is 5 mm average length of short fiber and 325-400 μm size distribution of particulate filler have been studied. Overall, EFB short fiber-HDPE composites yield higher mechanical properties compared to EFB particulate-HDPE composites. For both types of composites, considerable improvement showed in tensile and flexural modulus. However, the tensile strength decreased with increase in EFB content. Attempts to improve these properties using alkali and two types of silane, namely γ-Methacryloxypropyltrimethoxysilane (MTS) and vinyltriethoxysilane (VTS) were described. It is found that both types of silane enhanced the mechanical properties of composites. MTS showed better tensile strength compared to VTS. However, only marginal improvement obtained from alkali treatments.

  10. Effect of electrolyte concentration on performance of supercapacitor carbon electrode from fibers of oil palm empty fruit bunches

    International Nuclear Information System (INIS)

    Fibers of oil palm empty fruit bunches were used to produce self-adhesive carbon grains (SACG). The SACG green monoliths were carbonized in N2 environment at 800°C to produce carbon monoliths (CM) and the CM was CO2 activated at 800°C for 4 hour to produce activated carbon monolith electrodes (ACM). The physical properties of the CMs and ACMs were investigated using X-ray diffraction, field emission scanning electron microscopy and nitrogen adsorption-desorption. ACMs were used as electrode to fabricate symmetry supercapacitor cells and the cells which used H2SO4 electrolyte at 0.5, 1.0 and 1.5 M were investigated using electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic charge-discharge standard techniques. In this paper we report the physical properties of the ACM electrodes and the effect of electrolyte concentration on the electrochemical properties the ACM electrodes

  11. "Bunched Black Swans" in Complex Geosystems: Cross-Disciplinary Approaches to the Additive and Multiplicative Modelling of Correlated Extreme Bursts

    Science.gov (United States)

    Watkins, N. W.; Rypdal, M.; Lovsletten, O.

    2012-12-01

    For all natural hazards, the question of when the next "extreme event" (c.f. Taleb's "black swans") is expected is of obvious importance. In the environmental sciences users often frame such questions in terms of average "return periods", e.g. "is an X meter rise in the Thames water level a 1-in-Y year event ?". Frequently, however, we also care about the emergence of correlation, and whether the probability of several big events occurring in close succession is truly independent, i.e. are the black swans "bunched". A "big event", or a "burst", defined by its integrated signal above a threshold, might be a single, very large, event, or, instead, could in fact be a correlated series of "smaller" (i.e. less wildly fluctuating) events. Several available stochastic approaches provide quantitative information about such bursts, including Extreme Value Theory (EVT); the theory of records; level sets; sojourn times; and models of space-time "avalanches" of activity in non-equilibrium systems. Some focus more on the probability of single large events. Others are more concerned with extended dwell times above a given spatiotemporal threshold: However, the state of the art is not yet fully integrated, and the above-mentioned approaches differ in fundamental aspects. EVT is perhaps the best known in the geosciences. It is concerned with the distribution obeyed by the extremes of datasets, e.g. the 100 values obtained by considering the largest daily temperature recorded in each of the years of a century. However, the pioneering work from the 1920s on which EVT originally built was based on independent identically distributed samples, and took no account of memory and correlation that characterise many natural hazard time series. Ignoring this would fundamentally limit our ability to forecast; so much subsequent activity has been devoted to extending EVT to encompass dependence. A second group of approaches, by contrast, has notions of time and thus possible non

  12. Single-bunch kicker pulser

    International Nuclear Information System (INIS)

    The single-bunch kicker magnet is powered by a capacitor discharge pulser. The ferrite-core magnet is used to kick out one of twelve proton bunches circulating in the AGS (Alternating Gradient Synchrotron) into the experimental area. The magnet current pulse has a half-sinusoid shape, with a peak current of 2800 A. The pulse current rises and falls to zero, with minimum undershoot, in 410 nsec to minimize effects on adjacent bunches. The magnet inductance is 1.0 μHy. The pulser is mounted on the kicker magnet in the AGS ring, and is exposed to ionizing radiation. The HVDC power supply, controls, monitoring, and auxiliary circuits are housed approximately 300 feet away external to the ring. A two-gap thyratron is used to discharge the energy storage capacitor. Two hydrogen diodes are series connected to function as an inverse diode

  13. Single-bunch kicker pulser

    Energy Technology Data Exchange (ETDEWEB)

    Frey, W.W.

    1983-01-01

    The single-bunch kicker magnet is powered by a capacitor discharge pulser. The ferrite-core magnet is used to kick out one of twelve proton bunches circulating in the AGS (Alternating Gradient Synchrotron) into the experimental area. The magnet current pulse has a half-sinusoid shape, with a peak current of 2800 A. The pulse current rises and falls to zero, with minimum undershoot, in 410 nsec to minimize effects on adjacent bunches. The magnet inductance is 1.0 ..mu..Hy. The pulser is mounted on the kicker magnet in the AGS ring, and is exposed to ionizing radiation. The HVDC power supply, controls, monitoring, and auxiliary circuits are housed approximately 300 feet away external to the ring. A two-gap thyratron is used to discharge the energy storage capacitor. Two hydrogen diodes are series connected to function as an inverse diode.

  14. Theoretical and Numerical Analyses of a Slit-Masked Chicane for Modulated Bunch Generation

    CERN Document Server

    Zhu, Xiaofang; Shin, Young-Min

    2015-01-01

    Density modulations on electron beams can improve machine performance of beam-driven accelerators and FELs with resonance beam-wave coupling. The beam modulation is studied with a masked chicane by the analytic model and simulations with the beam parameters of the Fermilab Accelerator Science and Technology (FAST) facility. With the chicane design parameters (bending angle of 18{\\deg}, bending radius of 0.95 m and R56 ~ - 0.19 m) and a nominal beam of 3 ps bunch length, the analytic model showed that a slit-mask with slit period 900 {\\mu}m and aperture width 300 {\\mu}m induces a modulation of bunch-to-bunch spacing ~100 {\\mu}m to the bunch with 2.4% correlated energy spread. With the designed slit mask and a 3 ps bunch, particle-in-cell (PIC) simulations, including nonlinear energy distributions, space charge force, and coherent synchrotron radiation (CSR) effect, also result in beam modulation with bunch-to-bunch distance around 100 {\\mu}m and a corresponding modulation frequency of 3 THz. The beam modulatio...

  15. Loss of Landau Damping for Bunch Oscillations

    CERN Document Server

    Burov, A

    2012-01-01

    Conditions for the existence, uniqueness and stability of self-consistent bunch steady states are considered. For the existence and uniqueness problems, simple algebraic criteria are derived for both the action and Hamiltonian domain distributions. For the stability problem, van Kampen theory is used. The onset of a discrete van Kampen mode means the emergence of a coherent mode without any Landau damping; thus, even a tiny couple-bunch or multi-turn wake is sufficient to drive the instability. The method presented here assumes an arbitrary impedance, RF shape, and beam distribution function. Available areas on the intensity-emittance plane are shown for resistive wall wake and single harmonic, bunch shortening and bunch lengthening RF configurations. Thresholds calculated for the Tevatron parameters and impedance model are in agreement with the observations. These thresholds are found to be extremely sensitive to the small-argument behaviour of the bunch distribution function. Accordingly, a method to increa...

  16. Analytic model of bunched beams for harmonic generation in the low-gain free electron laser regime

    International Nuclear Information System (INIS)

    One scheme for harmonic generation employs free electron lasers (FELs) with two undulators: the first uses a seed laser to modulate the energy of the electron beam; following a dispersive element which acts to bunch the beam, the second undulator radiates at a higher harmonic. These processes are currently evaluated using extensive calculations or simulation codes which can be slow to evaluate and difficult to set up. We describe a simple algorithm to predict the output of a harmonic generation beamline in the low-gain FEL regime, based on trial functions for the output radiation. Full three-dimensional effects are included. This method has been implemented as a Mathematica package, named CAMPANILE, which runs rapidly and can be generalized to include effects such as asymmetric beams and misalignments. This method is compared with simulation results using the FEL code GENESIS, both for single stages of harmonic generation and for the LUX project, a design concept for an ultrafast X-ray facility, where multiple stages upshift the input laser frequency by factors of up to 200

  17. Bunch evolution study in optimization of MeV ultrafast electron diffraction

    OpenAIRE

    Lu, Xianhai; Du, Yingchao; Huang, Wenhui; Tang, Chuanxiang

    2014-01-01

    Megaelectronvolt ultrafast electron diffraction (UED) is a promising detection tool for ultrafast processes. The quality of diffraction image is determined by the transverse evolution of the probe bunch. In this paper, we study the contributing terms of the emittance and space charge effects to the bunch evolution in MeV UED scheme, employing a mean-field model with an ellipsoidal distribution as well as particle tracking simulation. Small transverse dimension of the drive laser is found crit...

  18. Semi-analytical 6D model of space charge force for dense electron bunches with a large energy spread

    International Nuclear Information System (INIS)

    Laser driven accelerators are capable of producing multi nC, multi MeV electron beams with transverse and longitudinal sizes on the order of microns. To investigate the transport of such electron bunches, a fast and fully relativistic space charge code which can handle beams with arbitrarily large energy spread has been developed. A 6-D macroparticle model for the beam is used to calculate the space charge fields at each time step. The collection of macroparticles is divided into longitudinal momentum bins, each with a small spread in relative momentum. The macroparticle distribution in each momentum bin is decomposed into ellipsoidal shells in position space. For each shell, an analytical expression for the electrostatic force in the bin rest frame is used. The total space charge force acting on one macroparticle in the lab frame is then the vector sum of the Lorentz-transformed forces from all the momentum bins. We have used this code to study the evolution of typical beams emerging from the plasma in the two most popular schemes, i.e., the self-modulated laser-wakefield-accelerator, where the laser pulse size is many times the plasma wavelength (L >> lr), and the colliding pulse laser-wakefield-accelerator regime where L-lr and two counter propagating laser pulses are used to inject electrons into the wakefield

  19. Theoretical and numerical analyses of a slit-masked chicane for modulated bunch generation

    Science.gov (United States)

    Zhu, X.; Broemmelsiek, D. R.; Shin, Y.-M.

    2015-10-01

    Density modulations on electron beams can improve machine performance of beam-driven accelerators and FELs with resonance beam-wave coupling. The beam modulation is studied with a masked chicane by the analytic model and simulations with the beam parameters of the Fermilab Accelerator Science and Technology (FAST) facility. With the chicane design parameters (bending angle of 18o, bending radius of 0.95 m and R56 ~ -0.19 m) and a nominal beam of 3 ps bunch length, the analytic model showed that a slit-mask with slit period 900 μ m and aperture width 300 μ m induces a modulation of bunch-to-bunch spacing ~ 100 μ m to the bunch with 2.4% correlated energy spread. With the designed slit mask and a 3 ps bunch, particle-in-cell (PIC) simulations, including nonlinear energy distributions, space charge force, and coherent synchrotron radiation (CSR) effect, also result in beam modulation with bunch-to-bunch distance around 100 μ m and a corresponding modulation frequency of 3 THz. The beam modulation has been extensively examined with three different beam conditions, 2.25 ps (0.25 nC), 3.25 ps (1 nC), and 4.75 ps (3.2 nC), by tracking code Elegant. The simulation analysis indicates that the sliced beam by the slit-mask with 3 ~ 6% correlated energy spread has modulation lengths about 187 μ m (0.25 nC), 270 μ m (1 nC) and 325 μ m (3.2 nC). The theoretical and numerical data proved the capability of the designed masked chicane in producing modulated bunch train with micro-bunch length around 100 fs.

  20. Effects of aqueous ammonia treatment on fiber's surface morphology and enzymatic digestibility of empty fruit bunch fiber (EFBF)

    Science.gov (United States)

    Ling, Tang Pei; Hassan, Osman

    2013-11-01

    This study was conducted to investigate the effects of aqueous ammonia reflux and soaked treatment on the fiber's surface morphology and enzymatic digestibility of empty fruit bunch fiber (EFBF). The surface morphological changes of the fiber after aqueous ammonia treatment was linked to the sugars yield by enzymatic hydrolysis. The effectiveness of 6.25% aqueous ammonia treatment in improving enzymatic digestibility of EFBF was initially studied in reflux system and by soaking. The results showed that soaked treatment was more effective than reflux system. Further study on soaked treatment of EFBF was carried out by increasing the ammonia concentration to 12.50%. Soaking in aqueous ammonia was conducted at 30°C and 50°C for 24 hours. The results of enzymatic hydrolysis showed that sugar yield from EFBF soaked in 12.50% aqueous ammonia at 50°C was the highest. Approximately 242.91±15.50 mg/g EFBF of xylose and 320.49±28.31 mg/g EFBF of glucose were produced by the action of enzyme Cellic Ctec 2. Results of scanning electron microscopic showed that aqueous ammonia treatment by soaking had caused a more severe structural distortion on the fiber's surface and higher removal of silica bodies that embedded on the fiber than those in reflux system. The changes on the fiber's surface morphology were believed is the contributing factor that improved the enzymatic digestibility of EFBF after aqueous ammonia treatment.

  1. Effects of aqueous ammonia treatment on fiber’s surface morphology and enzymatic digestibility of empty fruit bunch fiber (EFBF)

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Tang Pei; Hassan, Osman [Department of Food Science, School of Chemical Science and Food Technology, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi UKM, Selangor (Malaysia)

    2013-11-27

    This study was conducted to investigate the effects of aqueous ammonia reflux and soaked treatment on the fiber’s surface morphology and enzymatic digestibility of empty fruit bunch fiber (EFBF). The surface morphological changes of the fiber after aqueous ammonia treatment was linked to the sugars yield by enzymatic hydrolysis. The effectiveness of 6.25% aqueous ammonia treatment in improving enzymatic digestibility of EFBF was initially studied in reflux system and by soaking. The results showed that soaked treatment was more effective than reflux system. Further study on soaked treatment of EFBF was carried out by increasing the ammonia concentration to 12.50%. Soaking in aqueous ammonia was conducted at 30°C and 50°C for 24 hours. The results of enzymatic hydrolysis showed that sugar yield from EFBF soaked in 12.50% aqueous ammonia at 50°C was the highest. Approximately 242.91±15.50 mg/g EFBF of xylose and 320.49±28.31 mg/g EFBF of glucose were produced by the action of enzyme Cellic Ctec 2. Results of scanning electron microscopic showed that aqueous ammonia treatment by soaking had caused a more severe structural distortion on the fiber’s surface and higher removal of silica bodies that embedded on the fiber than those in reflux system. The changes on the fiber’s surface morphology were believed is the contributing factor that improved the enzymatic digestibility of EFBF after aqueous ammonia treatment.

  2. Effects of aqueous ammonia treatment on fiber’s surface morphology and enzymatic digestibility of empty fruit bunch fiber (EFBF)

    International Nuclear Information System (INIS)

    This study was conducted to investigate the effects of aqueous ammonia reflux and soaked treatment on the fiber’s surface morphology and enzymatic digestibility of empty fruit bunch fiber (EFBF). The surface morphological changes of the fiber after aqueous ammonia treatment was linked to the sugars yield by enzymatic hydrolysis. The effectiveness of 6.25% aqueous ammonia treatment in improving enzymatic digestibility of EFBF was initially studied in reflux system and by soaking. The results showed that soaked treatment was more effective than reflux system. Further study on soaked treatment of EFBF was carried out by increasing the ammonia concentration to 12.50%. Soaking in aqueous ammonia was conducted at 30°C and 50°C for 24 hours. The results of enzymatic hydrolysis showed that sugar yield from EFBF soaked in 12.50% aqueous ammonia at 50°C was the highest. Approximately 242.91±15.50 mg/g EFBF of xylose and 320.49±28.31 mg/g EFBF of glucose were produced by the action of enzyme Cellic Ctec 2. Results of scanning electron microscopic showed that aqueous ammonia treatment by soaking had caused a more severe structural distortion on the fiber’s surface and higher removal of silica bodies that embedded on the fiber than those in reflux system. The changes on the fiber’s surface morphology were believed is the contributing factor that improved the enzymatic digestibility of EFBF after aqueous ammonia treatment

  3. Single bunch transverse instability in a circular accelerator with chromaticity and space charge

    International Nuclear Information System (INIS)

    The transverse instability of a bunch in a circular accelerator is elaborated in this paper. A new tree-modes model is proposed and developed to describe the most unstable modes of the bunch. This simple and flexible model includes chromaticity and space charge, and can be used with any bunch and wake forms. The dispersion equation for the bunch eigentunes is obtained in form of a third-order algebraic equation. The known head-tail and TMCI modes appear as the limiting cases which are distinctly bounded at zero chromaticity only. It is shown that the instability parameters depend only slightly on the bunch model but they are rather sensitive to the wake shape. In particular, space charge effects are investigated in the paper and it is shown that their influence depends on sign of wake field enhancing the bunch stability if the wake is negative. The resistive wall wake is considered in detail including a comparison of single and collective effects. A comparison of the results with earlier publications is carried out

  4. Klystron instability of a relativistic electron beam in a bunch compressor

    International Nuclear Information System (INIS)

    In this paper, we consider a klystron-like mechanism of amplification of parasitic density modulations in an electron bunch passing a magnetic bunch compressor. Analytical expressions are derived for the small-signal gain. The effect of wakefields in front of the bunch compressor is analyzed by using a model of linear compression which assumes linear correlated energy chirp and linear dependence of a path length on energy deviation. Analysis of the density modulation growth due to coherent synchrotron radiation inside bends of the magnetic bunch compressor is done for the simplified case of no correlated energy chirp (no compression). Analytical results of this paper can be used for benchmarking numerical simulation codes

  5. Impedance model of the CERN SPS and aspects of LHC single-bunch stability

    CERN Document Server

    Salvant, Benoit; Metral, Elias

    2010-01-01

    Upgrades of the CERN particle accelerators complex are planned to increase the potential of physics discovery in the LHC. In this respect, the beam coupling impedances of the SPS and LHC are expected to be among the limitations to the intensity upgrade scheme. In this thesis work, we present a general framework to better understand the impedance of a particle accelerator. In a first step, the impedance of single components are gathered into an impedance model accounting for the whole machine. In order to assess the relevance of this impedance model, its impact on beam dynamics is simulated and can be compared to impedance observables measured with beam. This general framework was applied to compute a more accurate transverse impedance model of the SPS from theoretical models for the 20 kickers and the 6.9 km long beam pipe, as well as time domain electromagnetic simulations of the 106 horizontal and 96 vertical SPS beam position monitors. Comparing HEADTAIL macroparticle simulations to beam-based measurements...

  6. Effect of electrolyte concentration on performance of supercapacitor carbon electrode from fibers of oil palm empty fruit bunches

    Energy Technology Data Exchange (ETDEWEB)

    Farma, R.; Awitdrus,; Taer, E. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Departement of Physics, Faculty of Mathematics and Natural Sciences, University of Riau, 28293 Pekanbaru, Riau (Indonesia); Deraman, M., E-mail: madra@ukm.my; Talib, I. A.; Omar, R.; Ishak, M. M.; Basri, N. H.; Dolah, B. N. M. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia)

    2015-04-16

    Fibers of oil palm empty fruit bunches were used to produce self-adhesive carbon grains (SACG). The SACG green monoliths were carbonized in N{sub 2} environment at 800°C to produce carbon monoliths (CM) and the CM was CO{sub 2} activated at 800°C for 4 hour to produce activated carbon monolith electrodes (ACM). The physical properties of the CMs and ACMs were investigated using X-ray diffraction, field emission scanning electron microscopy and nitrogen adsorption-desorption. ACMs were used as electrode to fabricate symmetry supercapacitor cells and the cells which used H{sub 2}SO{sub 4} electrolyte at 0.5, 1.0 and 1.5 M were investigated using electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic charge-discharge standard techniques. In this paper we report the physical properties of the ACM electrodes and the effect of electrolyte concentration on the electrochemical properties the ACM electrodes.

  7. Effect of ultrasonic pre-treatment on low temperature acid hydrolysis of oil palm empty fruit bunch.

    Science.gov (United States)

    Yunus, Robiah; Salleh, Shanti Faridah; Abdullah, Nurhafizah; Biak, Dyg Radiah Awg

    2010-12-01

    Various pre-treatment techniques change the physical and chemical structure of the lignocellulosic biomass and improve hydrolysis rates. The effect of ultrasonic pre-treatment on oil palm empty fruit bunch (OPEFB) fibre prior to acid hydrolysis has been evaluated. The main objective of this study was to determine if ultrasonic pre-treatment could function as a pre-treatment method for the acid hydrolysis of OPEFB fibre at a low temperature and pressure. Hydrolysis at a low temperature was studied using 2% sulphuric acid; 1:25 solid liquid ratio and 100 degrees C operating temperature. A maximum xylose yield of 58% was achieved when the OPEFB fibre was ultrasonicated at 90% amplitude for 45min. In the absence of ultrasonic pre-treatment only 22% of xylose was obtained. However, no substantial increase of xylose formation was observed for acid hydrolysis at higher temperatures of 120 and 140 degrees C on ultrasonicated OPEFB fibre. The samples were then analysed using a scanning electron microscope (SEM) to describe the morphological changes of the OPEFB fibre. The SEM observations show interesting morphological changes within the OPEFB fibre for different acid hydrolysis conditions. PMID:20719502

  8. Bunch identification module

    International Nuclear Information System (INIS)

    This module provides bunch identification and timing signals for the PEP Interaction areas. Timing information is referenced to the PEP master oscillator, and adjusted in phase as a function of region. Identification signals are generated in a manner that allows observers in all interaction regions to agree on an unambiguous bunch identity. The module provides bunch identification signals via NIM level logic, upon CAMAC command, and through LED indicators. A front panel ''region select'' switch allows the same module to be used in all regions. The module has two modes of operation: a bunch identification mode and a calibration mode. In the identification mode, signals indicate which of the three bunches of electrons and positrons are interacting, and timing information about beam crossing is provided. The calibration mode is provided to assist experimenters making time of flight measurements. In the calibration mode, three distinct gating signals are referenced to a selected bunch, allowing three timing systems to be calibrated against a common standard. Physically, the bunch identifier is constructed as a single width CAMAC module. 2 figs., 1 tab

  9. Models to estimate the bunch dry weight in african oil palm (elaeis guineensis jacq.), american oil palm (elaeis oleifera h.b.k. cortes) and the interspecific hybrid (e. oleifera x e. guineensis)

    OpenAIRE

    2012-01-01

    Statistical models were used to estimate the bunch dry weight through indirect nondestructive methods in African oil palm (Elaeis guineensis) American oil palm (Elaeis oleifera) and the interspecific hybrid (E. oleifera x E. guineensis); and compared with the formula proposed by Corley. The studies were conducted at Santa Barbara and Chaparral-Cuernavaca on the Unipalma plantation, located in the eastern palm region of Colombia. Ten palms were selected for each group and 30 bunches were sampl...

  10. Bioactive Compounds Isolated from Lignin of Empty Bunch Palm Fiber and Their Effects on in Vitro Rumen Fermentation

    Directory of Open Access Journals (Sweden)

    M. Prayuwidayati

    2015-12-01

    Full Text Available The objective of this experiment was to study the effects of bioactive compounds isolated from purified lignin formacell (PLF of empty bunch palm fiber as natural antimicrobes and their effects on in vitro rumen fermentation. The first experiment was inhibition test of 11 bioactive compounds isolated from PLF, using disc diffusion method against the growth of Escherichia coli, Salmonella typhimurium, and Staphylococcus aureus. Four of the most potential bioactive compounds were then used in the second experiment, which was an in vitro test using fresh rumen liquid of Ongole grade beef cattle, to study their effects on rumen fermentation. Six treatments with 3 replications were applied in a completely randomized block (CRB design. The treatments were R0= 0.5 g basal diet; R1= R0 + 0.3 mg Rumensin®; R2= R0 + 0.3 mg syringaldehyde; R3= R0 + 0.3 mg p-hydroxybenzoic acid; R4= R0 + 0.3 mg m-hydroxybenzoic acid; and R5= R0 + 0.3 mg oxybenzene. Isolate fraction of CC-2 (syringaldehyde, CC-3 (m-hydroxybenzoic acid, VLC-5 (oxybenzene, and VLC-9 (p-hydroxybenzoic acid exhibited antimicrobes activity against all tested bacteria. Other isolated fractions exhibited antimicrobes activity only against 1 or 2 tested bacteria. The use of syringaldehyde, p-hydroxybenzoic acid, m-hydroxybenzoic acid, and oxybenzene improved ammonia concentration, microbial protein synthesis, and nutrients digestibility. Bioactive compounds had no effect on rumen pH but reduced total VFA concentration as well as the estimate of methane production.

  11. Modelling and Measurements of Bunch Profiles at the LHC Flat Bottom

    CERN Document Server

    Papadopoulou, Stefania; Muller, Juan; Papaphilippou, Yannis; Trad, Georges

    2016-01-01

    At the LHC flat bottom the interplay between a series of effects (i.e. intrabeam scattering, longitudinal beam manipulations, non-linearities of the machine, etc) can lead to a population of the tails of the beam distributions, which may become non-Gaussian. This paper presents observations of the evolution of particle distributions in the LHC flat bottom. Novel distribution functions are employed to represent the beam profiles, and used as a guideline for generalising emittance growth rate estimations due to IBS. Finally, an attempt is made to benchmark an IBS Monte-Carlo simulation code, able to track 3D particle distributions, with the measured beam profile evolutions.

  12. Terahertz radiation as a bunch diagnostic for laser-wakefield-accelerated electron bunches

    Energy Technology Data Exchange (ETDEWEB)

    van Tilborg, Jeroen; Schroeder, Carl; Filip, Catalin; Toth, Csaba; Geddes, Cameron; Fubiani, Gwenael; Esarey, Eric; Leemans, Wim

    2011-06-17

    Experimental results are reported from two measurement techniques (semiconductor switching and electro-optic sampling) that allow temporal characterization of electron bunches produced by a laser-driven plasma-based accelerator. As femtosecond electron bunches exit the plasma-vacuum interface, coherent transition radiation (at THz frequencies) is emitted. Measuring the properties of this radiation allows characterization of the electron bunches. Theoretical work on the emission mechanism is presented, including a model that calculates the THz wave form from a given bunch profile. It is found that the spectrum of the THz pulse is coherent up to the 200 {micro}m thick crystal (ZnTe) detection limit of 4 THz, which corresponds to the production of sub-50 fs (rms) electron bunch structure. The measurements demonstrate both the shot-to-shot stability of bunch parameters that are critical to THz emission (such as total charge and bunch length), as well as femtosecond synchronization among bunch, THz pulse, and laser beam.

  13. Effect of irradiation ad incubation of palm oil empty fruit bunch medium on the Growth of rice mushroom (volvariella volvaceae)

    International Nuclear Information System (INIS)

    Study on the effect of irradiation and time incubation of composted palm oil empty fruit bunch (EFB) were conducted in growth chamber in the plastic bag as growth medium. Treatments were consisted of sterilization of composted EFB growth medium by autoclave heating were conducted at 2.0 kg/cm2 for 40 minutes and gamma irradiation at the dose of 0, 15, 30, and 45kGy. After sterilization, EFB medium were inoculated using mushroom seed of V. volvaceae. The time of incubation of EFB medium after inoculation was 2 and 4 weeks before mushroom harvesting. Growth chamber was maintained at 28-35 0C room temperature and humidity > 80%. Parameters of the experiment were determined on mushroom analysis i.e. fat, protein, and content and weight of mushroom. analysis od EFB medium after incubation were determined i.e. total fiber and percentage of rendement. Results of the experiment showed that dose of 45 kGy effected on mushroom fat content 0.52% which was decreasing regards to the delay of incubation period. Irradiation treatment did not effect EFB fat content compared to non irradiated EFB (0.82%). Irradiation treatment and one.variety produced number of plaincreasing on mushroom protein content. Mushroom starch content was obtained on the dose of 15 kGy and 4 weeks of incubation period 3.09 and 3.13% respectively. The dose of 45 kGy and autoclave heating were decreasing total fiber of EFB medium 29.29 and 28.02% respectively. The dose of 45 kGy on EFB medium with 2 weeks of incubation period produced weight of mushroom 30.92 and 27.73 g/bag respectively. (author)

  14. KEKB bunch feedback systems

    Energy Technology Data Exchange (ETDEWEB)

    Tobiyama, M.; Kikutani, E. [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

    1996-08-01

    Design and the present status of the bunch by bunch feedback systems for KEKB rings are shown. The detection of the bunch oscillation are made with the phase detection for longitudinal plane, the AM/PM method for transverse plane. Two GHz component of the bunch signal which is extracted with an analog FIR filter is used for the detection. Hardware two-tap FIR filter systems to shift the phase of the oscillation by 90deg will be used for the longitudinal signal processing. The same system will be used with no filtering but with only digital delay for transverse system. The candidate for the kicker and the required maximum power are also estimated. (author)

  15. Quick-scan estimating model of higher heating value of oil palm empty fruit bunches based on ash from proximate analysis data

    OpenAIRE

    Villegas, Jorge; Avila, Humberto

    2014-01-01

    A correlation model for a quick-scan estimation of the Higher Heating Value (HHV) of Oil Palm Empty Fruit Bunches (EFB) base on proximate analysis is presented in this paper. The proximate analysis variables Fixed Carbon (FC), Ash Content (Ash), Volatile Matter (VM), Residual Moisture were analyzed statistically to obtain a model to estimate HHV which can be used as a support for evaluating the energetic disponibility of the EFB,  with Ash content as the input variable.  The samples were take...

  16. Coupled Bunch Instabilities in the LHC

    CERN Document Server

    Angal-Kalinin, Deepa

    2002-01-01

    In the LHC, the coupled bunch instabilities will be mainly driven by the RF cavities and the resistive wall effect. The growth times of these instabilities have been estimated taking into consideration the undamped and damped higher order modes of these cavities. These estimates show that the rise times of the longitudinal coupled bunch instabilities are under control. The proposed transverse feed-back system allows the same conclusion to be drawn for the transverse resistive wall instability.

  17. Ion stability in electron bunch train

    International Nuclear Information System (INIS)

    The self-consistent theory of ion stability in electron bunch train is described. Change in ion skeleton density caused by ion motion in a bunch focusing field and in defocusing intrinsic field is taken into account in the theory. The functional dependence of the maximum possible coefficient of charge compensation of the beam by the current of this beam and geometry of bunches composing it is determined on the basis of the supposition about the periodic laminar ion motion at the limit of their stability. Calculation results are given for cases of cylindrical and plane cross sections of beams with uniform electron density in the bunches. The results of a numerical experiment on studying the dependence of compensation on beam intensity are presented. Comparison of these results with predictions of the self-consistent theory and the heavy skeleton theory known early confirms the foundation of model suppositions of the self-consistent theory

  18. Structural changes in bunched crystalline ion beams

    International Nuclear Information System (INIS)

    Measurements of the spatial distribution of bunched crystalline ion beams in the radio frequency quadrupole storage ring PALLAS are presented for different ratios of the longitudinal and the transverse confinement strengths. The length of highly elongated crystalline ion bunches and its dependence on the bunching voltage is compared to predictions for a one-dimensional ion string and three-dimensional space-charge-dominated beams. The length is found to be considerably shorter than that predicted by the models. Furthermore, the scaling of the length with the bunching voltage is shown to differ from the expected inverse cube root scaling. These differences can partially be attributed to the formation of a mixed crystalline structure. Additionally, a concise mapping of the structural transition from a string to a zig-zag configuration as a function of the ratio of the confinement strengths is presented, which in a similar way deviates from the predictions

  19. Structural changes in bunched crystalline ion beams

    CERN Document Server

    Bussmann, M; Schätz, T; Habs, D

    2003-01-01

    Measurements of the spatial distribution of bunched crystalline ion beams in the radio frequency quadrupole storage ring PALLAS are presented for different ratios of the longitudinal and the transverse confinement strengths. The length of highly elongated crystalline ion bunches and its dependence on the bunching voltage is compared to predictions for a one-dimensional ion string and three-dimensional space-charge-dominated beams. The length is found to be considerably shorter than that predicted by the models. Furthermore, the scaling of the length with the bunching voltage is shown to differ from the expected inverse cube root scaling. These differences can partially be attributed to the formation of a mixed crystalline structure. Additionally, a concise mapping of the structural transition from a string to a zig-zag configuration as a function of the ratio of the confinement strengths is presented, which in a similar way deviates from the predictions.

  20. Single-bunch longitudinal instability

    International Nuclear Information System (INIS)

    A theoretical analysis is given of the recently observed microwave instability in storage rings. It is shown that one expects a threshold proportional to impedance R/sub S/ in the limit of very large or small resonator bandwidths, with the threshold lower by the bunching factor for the large bandwidth case. For intermediate bandwidths, the threshold should be proportional to the area under the resonance curve, so de-Qing resonators will have little effect in this region

  1. Sensitivity of the CSR self-interaction to the local longitudinal charge concentration of an electron bunch

    International Nuclear Information System (INIS)

    Recent measurements of the coherent synchrotron radiation (CSR) effects indicated that the observed emittance growth and energy modulation due to the orbit-curvature-induced bunch self-interaction are sometimes bigger than predictions based on Gaussian longitudinal charge distributions. In this paper, by performing a model study, we show both analytically and numerically that when the longitudinal bunch charge distribution involves concentration of charges in a small fraction of the bunch length, enhancement of the CSR self-interaction beyond the Gaussian prediction may occur. The level of this enhancement is sensitive to the level of the local charge concentration

  2. Sensitivity of the CSR Self-Interaction to the Local Longitudinal Charge Concentration of an Electron Bunch

    International Nuclear Information System (INIS)

    Recent measurements of the coherent synchrotron radiation (CSR) effect carried out at CERN and at Jefferson Lab indicate that the observed emittance growth and energy modulation due to the orbit-curvature-induced bunch self-interaction are sometimes bigger than the results predicted from previous analyses and simulations based on a Gaussian longitudinal charge distribution. In this paper, by performing a model study, we show both analytically and numerically that when the longitudinal bunch charge distribution involves concentration of charges in a small fraction of the bunch length, enhancement of the CSR self-interaction beyond the Gaussian prediction may occur

  3. Effect of beam pre-bunching on gain and efficiency in a surface wave-pumped free electron laser

    Science.gov (United States)

    Sharma, Suresh C.; Sharma, Jyotsna; Bhasin, Anuradha; Walia, Ritu; Walia

    2012-12-01

    A pre-bunched relativistic electron beam (REB) counter-propagating to the surface wave in the vacuum region Compton backscatters the surface wave into a high-frequency coherent radiation. Plasma supports the surface wave that acquires a large wave number k 0 z around pump wave frequency $\\omega _0 = {{\\omega _p } {/ {\\vphantom {{\\omega _p } {\\sqrt 2 }}} \\kern-\

  4. Single-Bunch Instability Driven by the Electron Cloud Effect in the Positron Damping Ring of the International Linear Collider

    OpenAIRE

    Pivi, Mauro; Raubenheimer, Tor O.; Ghalam, Ali; Harkay, Katherine; Ohmi, Kazuhito; Wanzenberg, Rainer; Wolski, Andrzej; Zimmermann, Frank

    2005-01-01

    Collective instabilities caused by the formation of anelectron cloud (EC) are a potential limitation to the performances of the damping rings for a future linear collider. In this paper, we present recent simulation results for the electron cloud build-up in damping rings of different circumferences and discuss the single-bunch instabilities driven by the electron cloud.

  5. Space Charge Mitigation by Hollow Bunches

    CERN Multimedia

    Oeftiger, AO

    2014-01-01

    To satisfy the requirements of the HL-LHC (High Luminosity Large Hadron Collider), the LHC injector chain will need to supply a higher brightness, i.e. deliver the same transverse beam emittances \\epsilon_{x,y} while providing a higher intensity N. However, a larger number of particles per bunch enhances space charge effects. One approach to mitigate the impact of space charge is to change the longitudinal phase space distribution: hollow bunches feature a depleted bunch centre and a densely populated periphery. Thus, the spatial line density maximum is depressed which ultimately decreases the tune spread imposed by space charge. Therefore, a higher intensity can be accepted while keeping the same overall space charge tune shift. 3 different methods to create hollow bunches in the PSBooster are simulated.

  6. Simulated Performance of an FIR-Based Feedback System to Control the Electron Cloud Single-Bunch Transverse Instabilities in the CERN SPS

    Energy Technology Data Exchange (ETDEWEB)

    Secondo, R.; Vay, J. L.; Venturini, M.; Fox, J. D.; Rivetta, C. H.; Hofle, W.

    2011-03-28

    The operation at high current of high-energy proton machines like the SPS at CERN is affected by transverse single-bunch instabilities due to the Electron Cloud effect [1]. As a first step toward modeling a realistic feedback control system to stabilize the bunch dynamics, we investigate the use of a Finite Impulse Response (FIR) filter to represent the processing channel. The effect of the processing channel on the bunch dynamics is analyzed using the macro-particle simulation package Wart-Posinst. We discuss the basic features of the feedback model, report on simulation results, and present our plans for further development of the numerical model.

  7. HLS bunch current measurement system

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Bunch current is an important parameter for studying the injection fill-pattern in the storage ring and the instability threshold of the bunch, and the bunch current monitor also is an indispensable tool for the top-up injection. A bunch current measurement (BCM) system has been developed to meet the needs of the upgrade project of Hefei Light Source (HLS). This paper presents the layout of the BCM system. The system based on a high-speed digital oscilloscope can be used to measure the bunch current and synchronous phase shift. To obtain the absolute value of bunch-by-bunch current, the calibration coefficient is measured and analyzed. Error analysis shows that the RMS of bunch current is less than 0.01 mA when bunch current is about 5 mA, which can meet project requirement.

  8. Terahertz radiation from laser accelerated electron bunches

    International Nuclear Information System (INIS)

    Coherent terahertz and millimeter wave radiation from laser accelerated electron bunches has been measured. The bunches were produced by tightly focusing (spot diameter ∼ 6 (micro)m) a high peak power (up to 10 TW), ultra-short ((ge)50 fs) laser pulse from a high repetition rate (10 Hz) laser system (0.8 (micro)m), onto a high density (>1019 cm-3) pulsed gas jet of length ∼ 1.5 mm. As the electrons exit the plasma, coherent transition radiation is generated at the plasma-vacuum boundary for wavelengths long compared to the bunch length. Radiation in the 0.3-19 THz range and at 94 GHz has been measured and found to depend quadratically on the bunch charge. The measured radiated energy for two different collection angles is in good agreement with theory. Modeling indicates that optimization of this table-top source could provide more than 100 (micro)J/pulse. Together with intrinsic synchronization to the laser pulse, this will enable numerous applications requiring intense terahertz radiation. This radiation can also be used as a powerful tool for measuring the properties of laser accelerated bunches at the exit of the plasma accelerator. Preliminary spectral measurements indicates that bunches as short as 30-50 fs have been produced in these laser driven accelerators

  9. Bunching and anti-bunching in electronic transport

    OpenAIRE

    Emary, Clive; Pöltl, Christina; Carmele, Alexander; Kabuss, Julia; Knorr, Andreas; Brandes, Tobias

    2012-01-01

    In quantum optics the $g^{(2)}$-function is a standard tool to investigate photon emission statistics. We define a $g^{(2)}$-function for electronic transport and use it to investigate the bunching and anti-bunching of electron currents. Importantly, we show that super-Poissonian electron statistics do not necessarily imply electron bunching, and that sub-Poissonian statistics do not imply anti-bunching. We discuss the information contained in $g^{(2)}(\\tau)$ for several typical examples of t...

  10. The device for bunch selffocussing

    International Nuclear Information System (INIS)

    The new device for damping the longitudinal single bunch instability in atotage rings is proposed. This simple device is the dielectric channel insert of definite length in vacuum chamber. The structure of wake fields, induced by intense bunch in such a channel is that, that backward action on bunch particles not leads to bunch selffocusing. The conditions under which this phenomenon reveals itself and can be applied to electron-positron storages are considered. 3 refs

  11. Effect of inoculum size on production of compost and enzymes from palm oil mill biogas sludge mixed with shredded palm empty fruit bunches and decanter cake

    OpenAIRE

    Tanawut Nutongkaew; Wiriya Duangsuwan; Suteera Prasertsan; Poonsuk Prasertsan

    2014-01-01

    The effect of inoculum size on production of compost and enzymes from palm oil mill biogas sludge (POMS) mixed with shredded palm empty fruit bunches (PEFB) and decanter cake (DC) was studied using the mixed culture LDD1 as an inoculum. Three piles of 50 kg mixture (POMS:PEFB:DC = 2:1:1) with different inoculum sizes of 0.0075% (treatment A), 0.015% (treatment B), and 0.030% (treatment C) were set up. The physicochemical parameters were measured during the composting. All the comp...

  12. Vibrations of blades bunches

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Pešek, Luděk

    Brno: Brno University of Technology, 2014 - (Fuis, V.), s. 520-523 ISBN 978-80-214-4871-1. ISSN 1805-8248. [Engineering Mechanics 2014 /20./. Svratka (CZ), 12.05.2014-15.05.2014] Institutional support: RVO:61388998 Keywords : damping * dry friction * five-blades-bunch * harmonic excitation * response curve Subject RIV: BI - Acoustics

  13. Multi-bunch energy compensation in the NLC bunch compressor

    International Nuclear Information System (INIS)

    The task of the NLC bunch compressor is to reduce the length of each bunch in a train of 90 bunches from 4 mm, at extraction from the damping ring, to about 100 μm, suitable for injection into the X-band main linac. This task is complicated by longitudinal long-range wake fields and the multi-bunch beam loading in the various accelerating sections of the compressor. One possible approach to compensate the multi-bunch beam loading is to add two RF systems with slightly different frequencies (' Δf' scheme) to each accelerating section, as first proposed by Kikuchi. This paper summarizes the choice of parameters for three such compensating sections, and presents simulation results of combined single- and multi-bunch dynamics for four different NLC versions. The multi-bunch energy compensation is shown to be straightforward and its performance to be satisfactory

  14. Bunch heating by coherent synchrotron radiation

    International Nuclear Information System (INIS)

    The authors discuss here effects which define the steady-state rms energy spread of a microbunch in a storage ring. It is implied that the longitudinal microwave instability is controlled by low α lattice. In this case the coherent synchrotron radiation, if exists, may be the main factor defining the bunch temperature. Another effect comes from the fact that a nonlinear momentum compaction of such lattices makes Haissinskii equation not applicable, and the coherent synchrotron radiation may effect not only bunch lengthening but the energy spread as well

  15. Bunch compression for an FEL at NLCTA

    International Nuclear Information System (INIS)

    As part of the design effort for a free electron laser driven by the Next Linear Collider Test Accelerator (NLCTA), the author reports studies of bunch-length compression utilizing the existing infrastructure and hardware. In one possible version of the NLCTA FEL, bunches with 900-microm FWHM length, generated by an S-band photo-injector, would be compressed to an rms length of 60--120 microm before entering the FEL undulator. It is shown that, using the present magnetic chicane, the bunch compression is essentially straightforward, and that almost all emittance-diluting effects, e.g. wakefields, chromaticity, or space charge in the bending magnets, are small. The only exception to this finding is the predicted increase of the horizontal emittance due to coherent synchrotron radiation (CSR). Estimates based on existing theories of coherent synchrotron radiation suggest a tripling or quadrupling of the initial emittance, which seems to preclude bunch compression during regular FEL operation. Serendipitously, the magnitude of the predicted emittance growth would, on the other hand, make the NLCTA chicane an excellent tool for measuring the effects of coherent synchrotron radiation. This will be of considerable interest to many future projects, in particular to the Linac Coherent Light Source (LCLS). As an aside, it is shown that coherent synchrotron radiation in a bending magnet gives rise to a minimum possible bunch length, which is very reminiscent of the Oide limit on the vertical spot size at the interaction point of a linear collider

  16. Analytical bunch compression studies for FLUTE

    CERN Document Server

    Schreck, M

    2014-01-01

    The current article deals with analytical bunch compression studies for FLUTE whose results are compared to simulations. FLUTE is a linac-based electron accelerator with a design energy of approximately 40 MeV currently being constructed at the Karlsruhe Institute of Technology. One of the goals of FLUTE is to generate electron bunches with their length lying in the femtosecond regime. In the first phase this will be accomplished using a magnetic bunch compressor. This compressor forms the subject of the studies presented. The paper is divided into three parts. The first part deals with pure geometric investigations of the bunch compressor where space charge effects and the back reaction of bunches with coherent synchrotron radiation (CSR) are neglected. The second part is dedicated to the treatment of space charge effects and the third part gives some analytical results on the emission of CSR. The upshot is that the results of the first and the third part agree quite well with what is obtained from simulatio...

  17. Loss of Landau Damping for Bunch Oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Burov, A.; /Fermilab

    2011-04-11

    Conditions for the existence, uniqueness and stability of self-consistent bunch steady states are considered. For the existence and uniqueness problems, simple algebraic criteria are derived for both the action and Hamiltonian domain distributions. For the stability problem, van Kampen theory is used. The onset of a discrete van Kampen mode means the emergence of a coherent mode without any Landau damping; thus, even a tiny couple-bunch or multi-turn wake is sufficient to drive the instability. The method presented here assumes an arbitrary impedance, RF shape, and beam distribution function. Available areas on the intensity-emittance plane are shown for resistive wall wake and single harmonic, bunch shortening and bunch lengthening RF configurations. Thresholds calculated for the Tevatron parameters and impedance model are in agreement with the observations. These thresholds are found to be extremely sensitive to the small-argument behaviour of the bunch distribution function. Accordingly, a method to increase the LLD threshold is suggested. This article summarizes and extends recent author's publications.

  18. Bunch evolution study in optimization of MeV ultrafast electron diffraction

    Science.gov (United States)

    Lu, Xian-Hai; Du, Ying-Chao; Huang, Wen-Hui; Tang, Chuan-Xiang

    2014-12-01

    Megaelectronvolt ultrafast electron diffraction (UED) is a promising detection tool for ultrafast processes. The quality of diffraction image is determined by the transverse evolution of the probe bunch. In this paper, we study the contributing terms of the emittance and space charge effects to the bunch evolution in the MeV UED scheme, employing a mean-field model with an ellipsoidal distribution as well as particle tracking simulation. The small transverse dimension of the drive laser is found to be critical to improve the reciprocal resolution, exploiting both smaller emittance and larger transverse bunch size before the solenoid. The degradation of the reciprocal spatial resolution caused by the space charge effects should be carefully controlled.

  19. Research of bunch by bunch data acquisition system in SSRF

    International Nuclear Information System (INIS)

    Background: In order to improve the synchrotron performance in the constant current mode, attentions should be paid to problems such as non-linear beam dynamics, broadband beam impedance, and position disturbance, etc. Purpose: To address these problems, a bunch by bunch data acquisition system (BBDAQ) is implemented for real-time bunch position monitoring, as well as the off-line data analysis for the Shanghai Synchrotron Radiation Facility (SSRF) storage ring. It can be applied to optimize new equipment impedance, filling pattern, injection mode, and raise threshold value of current instability. Methods: This BBDAQ developed at SSRF consists a RF front end to filter and expand bunch signal to 2 ns, a data acquisition and processing card to sample bunch signal with four 125-MHz ADCs, which make an equivalent 500-MHz sampling rate, and the EPICS for post-processing to give bunch position and tune value. Results: Online experimental results show that the system can measure bunch by bunch position and tune value successfully. Conclusion: The development of bunch by bunch data acquisition system provides an efficient tool to analyze beam impedance, coupling instability, nonlinear dynamics. It makes further improvement of synchrotron performance visible. (authors)

  20. Measurement of Satellite Bunches at the LHC

    CERN Document Server

    Jeff, A; Boccardi, A; Bozyigit, S; Bravin, E; Lefevre, T; Rabiller, A; Roncarolo, F; Welsch, C P; Fisher, A S

    2012-01-01

    The RF gymnastics involved in the delivery of proton and lead ion bunches to the LHC can result in satellite bunches of varying intensity occupying the nominally empty RF buckets. Quantification of these satellites is crucial for bunch-by-bunch luminosity normalization as well as for machine protection. We present an overview of the longitudinal density monitor (LDM) which is the principal instrument for the measurement of satellite bunches in the LHC. The LDM uses single photon counting of synchrotron light. The very high energies reached in the LHC, combined with a dedicated undulator for diagnostics, allow synchrotron light measurements to be made with both protons and heavy ions. The arrival times of photons are collected over a few million turns, with the resulting histogram corrected for the effects of the detector’s deadtime and afterpulsing in order to reconstruct the longitudinal profile of the entire LHC ring. The LDM has achieved a dynamic range in excess of 105 and a time resolution of 90 ps. Ex...

  1. Peak Current Optimization for LCLS Bunch Compressor 2

    International Nuclear Information System (INIS)

    In this study, we calculate the effects of Coherent Synchrotron Radiation (CSR) in the LCLS bunch compression section BC2[3] on the resulting FEL performance, considering a realistic, strongly non-gaussian longitudinal charge distribution. The longitudinal chirping required for the bunch compression process leads to a non-linear, non-monotonous (delta)(z) functional dependence (Fig. 1 shows the current distribution and the energy offset along the bunch). We model this functional dependence by matching it to a cubic polynomial (delta) ∼ c0 + c1z + c2z2 + c3z3. During compression, the charge distribution in the z-(delta) plane will ''fold over'', as shown in fig. 2. This leads to a cusp at each end of the current distribution I(z), as shown in figure 3. High |l'(z)| values will lead to high longitudinal CSR fields, with possible detrimental effects on the transverse projected and slice emittance as well as energy spread, possibly affecting FEL performance

  2. Bunch Compressor for Beam-Based Alignment

    CERN Document Server

    Latina, A; Schulte, D

    2007-01-01

    Misalignments in the main linac of future linear colliders can lead to significant emittance growth. Beam-based alignment algorithms, such as Dispersion Free Steering (DFS), are necessary to mitigate these effects. We study how to use the Bunch Compressor to create the off-energy beams necessary for DFS and discuss the effectiveness of this method.

  3. Single Bunch Monopole Instability

    Energy Technology Data Exchange (ETDEWEB)

    Podobedov, B.; Heifets, S.; /SLAC

    2005-09-12

    We study single bunch stability with respect to monopole longitudinal oscillations in electron storage rings. Our analysis is different from the standard approach based on the linearized Vlasov equation. Rather, we reduce the full nonlinear Fokker-Planck equation to a Schroedinger-like equation which is subsequently analyzed by perturbation theory. We show that the Haissinski solution [3] may become unstable with respect to monopole oscillations and derive a stability criterion in terms of the ring impedance.

  4. Bunched beam longitudinal instability: Coherent dipole motion

    International Nuclear Information System (INIS)

    In this paper, the authors present a new formulation for the longitudinal coherent dipole motion, where a quadrature response of the environmental impedance is shown to be the effective longitudinal impedance for the beam instability. The Robinson-Pedersen formulation for the longitudinal dipole motion is also presented, the difference of the two approaches is discussed in the comparison. The results by using the Sacherer integral equation for the coherent dipole motion can generate the same results as by using the other two approaches, except for a scaling difference. The formulation is further generalized to the rigid bunch motion using signal analysis method, where a form factor shows up naturally. Finally, the formulation is applied to solve the coupled bunch instabilities. Examples of the AGS Booster and the AGS coupled bunch instabilities are used to illustrate the applications of the formulation

  5. Electron Bunch Train Excited Higher-Order Modes in a Superconducting RF Cavity

    CERN Document Server

    Gao, Yongfeng; Wang, Fang; Feng, Liwen; Zhuang, Dehao; Lin, Lin; Zhu, Feng; Hao, Jiankui; Quan, Shengwen; Liu, Kexin

    2016-01-01

    Higher-order mode (HOM) based intra-cavity beam diagnostics has been proved effectively and conveniently in superconducting radio-frequency (SRF) accelerators. Our recent research shows that the beam harmonics in the bunch train excited HOM spectrum, which have much higher signal-to-noise ratio than the intrinsic HOM peaks, may also be useful for beam diagnostics. In this paper, we will present our study on bunch train excited HOMs, including the theoretic model and recent experiments carried out based on the DC-SRF photoinjector and SRF linac at Peking University.

  6. Misalignment study of NLC bunch compressor

    International Nuclear Information System (INIS)

    Results of computer simulations of the misalignments in the 180 degree-bend angle second-stage bunch compressor for the NLC are described. The aim of this study was to evaluate alignment and production error tolerances. Three versions of the second stage, differing in their minimum obtainable bunch length (44 μ, 60 μ, and 86 μ) were studied. Simulations included orbit correction produced by errors and misalignments of the compressor elements. The orbit correction itself was done within some error margins. The effects of misalignments on transverse emittance growth were found. Recommendations for alleviating alignment tolerances are discussed

  7. Measurement of femtosecond electron bunches

    International Nuclear Information System (INIS)

    Bunch lengths as short as 84 fs (rms) have been measured at Jefferson Lab using a zero-phasing RF technique. To the best of our knowledge, this is the first accurate bunch length measurement in this regime. In this letter, an analytical approach for computing the longitudinal distribution function and bunch length is described for arbitrary longitudinal and transverse distributions. The measurement results are presented, which are in excellent agreement with numerical simulations

  8. Single bunch stability in the ESRF

    International Nuclear Information System (INIS)

    The longitudinal wake potential/impedance and bunch lengthening/stability in ESRF were studied. A cylindrical approximation of individual components of the vacuum chamber were studied. The results are wake potential and loss parameters. Measurements are necessary when the cylindrical approximation is not realistic. The coaxial wire method which is used gives a wake potential that can be substituted for the computed wake in the analysis. A measurement bench is presently being tested at ESRF. Wake potentials (computed or measured) are added before modeling or approximation is made. The impedance model used is the broad-band resonator model. Equations are derived for the longitudinal potential well. The bunch shape can be estimated knowing the first moments of the line density function. Mode coupling cannot explain the turbulent instability threshold. The threshold has then to be estimated by crude assumptions on potential well or bunch shape distortions. In the ESRF case, this threshold corresponds to a value of asymmetry s(th) = 0.6. Above the threshold the bunch lengthens with this constant asymmetry value

  9. Achromat with linear space charge for bunched beams

    International Nuclear Information System (INIS)

    The standard definition for an achromat is a transport line having zero values for the spatial dispersion (R16) and the angular dispersion (RZ6). For a bunched beam with linear space charge this definition of achromaticity does not hold. The linear space charge in the presence of a bend provides coupling between (a) bunch spatial width and bunch length (R1.5) and (b) bunch angular spread and bunch length (R25). Therefore, achromaticity should be redefined as a line having zero values of the spatial dispersion (R16), the angular dispersion (R26), and matrix elements R15 and R25. These additional conditions (R15=R25=0) can be achieved, for example, with two small RF cavities at appropriate locations in the achromat, to cancel space charge effects. An example of the application of this technique to the Spallation Neutron Source (SNS) high energy beam transport line is presented

  10. Short bunched beam monitor

    International Nuclear Information System (INIS)

    In order to monitor the short bunched beam, two types of monitors were developed and tested. A core monitor using a Co-based amorphous core which has high μ characteristics and high frequency response can be used as a non-destructive current monitor for the beam in the range of 1ns to several μs pulse width. A wall current monitor designed carefully has been also tested. The wall current monitor has measured the beam shape with the pulse width of 200ps or less. In this paper the characteristics and overall performance of these monitors are described. (author)

  11. Downsampled bunch-by-bunch feedback for PEP II

    International Nuclear Information System (INIS)

    The PEP II B Factory requires a feedback system to damp out longitudinal synchrotron oscillations. A time-domain bunch-by-bunch feedback system has been proposed in which each bunch is treated as an oscillator being driven by disturbances from the other bunches. The phase is detected, filtered, and the feedback correction signal is applied by the kicker. Since we are damping energy oscillations using measurements of phase, the required feedback signal must be proportional to the amplitude of the phase oscillations but phase shifted by 90 degrees. This signal must be calculated for each of the 1658 bunches, in parallel. In the original proposal, it was estimated that a farm of approximately 480 digital signal processors (DIPS) would be required to implement the feedback system. However, using the technique of downsampling, this number can be reduced to about 50 DIPS. In what follows, we will briefly explain the basic idea of downsampling and its implementation

  12. Downsampled bunch-by-bunch feedback for PEP II

    International Nuclear Information System (INIS)

    The PEP 11 B Factory requires a feedback system to damp out longitudinal synchrotron oscillations. A time-domain bunch-by-bunch feedback system has been proposed in which each bunch is treated as an oscillator being driven by disturbances from the other bunches. The phase is detected, filtered, and the feedback correction signal is applied by the kicker. Since we are damping energy oscillations using measurements of phase, the required feedback signal must be proportional to the amplitude of the phase oscillations but phase shifted by 90 degrees. This signal must be calculated for each of the 1658 bunches, in parallel. In the original proposal, it was estimated that a farm of approximately 480 digital signal processors (DSPS) would be required to implement the feedback system. However, using the technique of downsampling, this number can be reduced to about 50 DSPS. In what follows, we will briefly explain the basic idea of downsampling and its implementation

  13. Simulation Results of a Feedback Control System to Damp Electron Cloud Single-Bunch Transverse Instabilities In The Cern SPS

    Energy Technology Data Exchange (ETDEWEB)

    Secondo, R.; Vay, J. L.; Venturini, M.; Fox, J. D.; Rivetta, C. H.; Hofle, W.

    2011-03-28

    Transverse Single-Bunch Instabilities due to the Electron Cloud effect are limiting the operation at high current of the SPS at CERN. Recently a high-bandwidth Feedback System has been proposed as a possible solution to stabilize the beam and is currently under study. We analyze the dynamics of the bunch actively damped with a simple model of the Feedback in the macro-particle code WARP, in order to investigate the limitations of the System such as the minimum amount of power required to maintain stability. We discuss the feedback model, report on simulation results and present our plans for further development of the numerical model.

  14. Effect of fungal and phosphoric acid pretreatment on ethanol production from oil palm empty fruit bunches (OPEFB).

    Science.gov (United States)

    Ishola, Mofoluwake M; Isroi; Taherzadeh, Mohammad J

    2014-08-01

    Oil palm empty fruit bunches (OPEFB), a lignocellulosic residue of palm oil industries was examined for ethanol production. Milled OPEFB exposed to simultaneous saccharification and fermentation (SSF) with enzymes and Saccharomyces cerevisiae resulted just in 14.5% ethanol yield compared to the theoretical yield. Therefore, chemical pretreatment with phosphoric acid, a biological pretreatment with white-rot fungus Pleurotus floridanus, and their combination were carried out on OPEFB prior to the SSF. Pretreatment with phosphoric acid, combination of both methods and just fungal pretreatment improved the digestibility of OPEFB by 24.0, 16.5 and 4.5 times, respectively. During the SSF, phosphoric acid pretreatment, combination of fungal and phosphoric acid pretreatment and just fungal pretreatment resulted in the highest 89.4%, 62.8% and 27.9% of the theoretical ethanol yield, respectively. However, the recovery of the OPEFB after the fungal pretreatment was 98.7%, which was higher than after phosphoric acid pretreatment (36.5%) and combined pretreatment (45.2%). PMID:24630370

  15. Effect of fiber esterification on fundamental properties of oil palm empty fruit bunch fiber/poly(butylene adipate-co-terephthalate) biocomposites.

    Science.gov (United States)

    Siyamak, Samira; Ibrahim, Nor Azowa; Abdolmohammadi, Sanaz; Yunus, Wan Md Zin Wan; Rahman, Mohamad Zaki Ab

    2012-01-01

    A new class of biocomposites based on oil palm empty fruit bunch fiber and poly(butylene adipate-co-terephthalate) (PBAT), which is a biodegradable aliphatic aromatic co-polyester, were prepared using melt blending technique. The composites were prepared at various fiber contents of 10, 20, 30, 40 and 50 wt% and characterized. Chemical treatment of oil palm empty fruit bunch (EFB) fiber was successfully done by grafting succinic anhydride (SAH) onto the EFB fiber surface, and the modified fibers were obtained in two levels of grafting (low and high weight percentage gain, WPG) after 5 and 6 h of grafting. The FTIR characterization showed evidence of successful fiber esterification. The results showed that 40 wt% of fiber loading improved the tensile properties of the biocomposite. The effects of EFB fiber chemical treatments and various organic initiators content on mechanical and thermal properties and water absorption of PBAT/EFB 60/40 wt% biocomposites were also examined. The SAH-g-EFB fiber at low WPG in presence of 1 wt% of dicumyl peroxide (DCP) initiator was found to significantly enhance the tensile and flexural properties as well as water resistance of biocomposite (up to 24%) compared with those of untreated fiber reinforced composites. The thermal behavior of the composites was evaluated from thermogravimetric analysis (TGA)/differential thermogravimetric (DTG) thermograms. It was observed that, the chemical treatment has marginally improved the biocomposites' thermal stability in presence of 1 wt% of dicumyl peroxide at the low WPG level of grafting. The improved fiber-matrix surface enhancement in the chemically treated biocomposite was confirmed by SEM analysis of the tensile fractured specimens. PMID:22408394

  16. Effect of Fiber Esterification on Fundamental Properties of Oil Palm Empty Fruit Bunch Fiber/Poly(butylene adipate-co-terephthalate Biocomposites

    Directory of Open Access Journals (Sweden)

    Mohamad Zaki AB Rahman

    2012-01-01

    Full Text Available A new class of biocomposites based on oil palm empty fruit bunch fiber and poly(butylene adipate-co-terephthalate (PBAT, which is a biodegradable aliphatic aromatic co-polyester, were prepared using melt blending technique. The composites were prepared at various fiber contents of 10, 20, 30, 40 and 50 wt% and characterized. Chemical treatment of oil palm empty fruit bunch (EFB fiber was successfully done by grafting succinic anhydride (SAH onto the EFB fiber surface, and the modified fibers were obtained in two levels of grafting (low and high weight percentage gain, WPG after 5 and 6 h of grafting. The FTIR characterization showed evidence of successful fiber esterification. The results showed that 40 wt% of fiber loading improved the tensile properties of the biocomposite. The effects of EFB fiber chemical treatments and various organic initiators content on mechanical and thermal properties and water absorption of PBAT/EFB 60/40 wt% biocomposites were also examined. The SAH-g-EFB fiber at low WPG in presence of 1 wt% of dicumyl peroxide (DCP initiator was found to significantly enhance the tensile and flexural properties as well as water resistance of biocomposite (up to 24% compared with those of untreated fiber reinforced composites. The thermal behavior of the composites was evaluated from thermogravimetric analysis (TGA/differential thermogravimetric (DTG thermograms. It was observed that, the chemical treatment has marginally improved the biocomposites’ thermal stability in presence of 1 wt% of dicumyl peroxide at the low WPG level of grafting. The improved fiber-matrix surface enhancement in the chemically treated biocomposite was confirmed by SEM analysis of the tensile fractured specimens.

  17. Effect of Fiber Esterification on Fundamental Properties of Oil Palm Empty Fruit Bunch Fiber/Poly(butylene adipate-co-terephthalate) Biocomposites

    Science.gov (United States)

    Siyamak, Samira; Ibrahim, Nor Azowa; Abdolmohammadi, Sanaz; Yunus, Wan Md Zin Wan; Rahman, Mohamad Zaki AB

    2012-01-01

    A new class of biocomposites based on oil palm empty fruit bunch fiber and poly(butylene adipate-co-terephthalate) (PBAT), which is a biodegradable aliphatic aromatic co-polyester, were prepared using melt blending technique. The composites were prepared at various fiber contents of 10, 20, 30, 40 and 50 wt% and characterized. Chemical treatment of oil palm empty fruit bunch (EFB) fiber was successfully done by grafting succinic anhydride (SAH) onto the EFB fiber surface, and the modified fibers were obtained in two levels of grafting (low and high weight percentage gain, WPG) after 5 and 6 h of grafting. The FTIR characterization showed evidence of successful fiber esterification. The results showed that 40 wt% of fiber loading improved the tensile properties of the biocomposite. The effects of EFB fiber chemical treatments and various organic initiators content on mechanical and thermal properties and water absorption of PBAT/EFB 60/40 wt% biocomposites were also examined. The SAH-g-EFB fiber at low WPG in presence of 1 wt% of dicumyl peroxide (DCP) initiator was found to significantly enhance the tensile and flexural properties as well as water resistance of biocomposite (up to 24%) compared with those of untreated fiber reinforced composites. The thermal behavior of the composites was evaluated from thermogravimetric analysis (TGA)/differential thermogravimetric (DTG) thermograms. It was observed that, the chemical treatment has marginally improved the biocomposites’ thermal stability in presence of 1 wt% of dicumyl peroxide at the low WPG level of grafting. The improved fiber-matrix surface enhancement in the chemically treated biocomposite was confirmed by SEM analysis of the tensile fractured specimens. PMID:22408394

  18. Dancing bunches as Van Kampen modes

    International Nuclear Information System (INIS)

    Van Kampen modes are eigen-modes of Jeans-Vlasov equation (1-3). Their spectrum consists of continuous and, possibly, discrete parts. Onset of a discrete van Kampen mode means emergence of a coherent mode without any Landau damping; thus, even a tiny couple-bunch wake is sufficient to drive instability. Longitudinal instabilities observed at Tevatron (4), RHIC (5) and SPS (6) can be explained as loss of Landau damping (LLD), which is shown here to happen at fairly low impedances. For repulsive wakes and single-harmonic RF, LLD is found to be extremely sensitive to steepness of the bunch distribution function at small amplitudes. Based on that, a method of beam stabilization is suggested. Emergence of a discrete van Kampen mode means either loss of Landau damping or instability. Longitudinal bunch stability is analysed in weak head-tail approximation for inductive impedance and single-harmonic RF. The LLD threshold intensities are found to be rather low: for cases under study all of them do not exceed a few percent of the zero-amplitude incoherent synchrotron frequency shift, strongly decreasing for shorter bunches. Because of that, LLD can explain longitudinal instabilities happened at fairly low impedances at Tevatron (4), and possibly for RHIC (5) and SPS (6), being in that sense an alternative to the soliton explanation (5, 20). Although LLD itself results in many cases in emergence of a mode with zero growth rate, any couple-bunch (and sometimes multi-turn) wake would drive instability for that mode, however small this wake is. LLD is similar to a loss of immune system of a living cell, when any microbe becomes fatal for it. The emerging discrete mode is normally very different from the rigid-bunch motion; thus the rigid-mode model significantly overestimates the LLD threshold. The power low of LLD predicted in Ref. (17) agrees with results of this paper. However, the numerical factor in that scaling low strongly depends on the bunch distribution function

  19. Dancing bunches as Van Kampen modes

    Energy Technology Data Exchange (ETDEWEB)

    Burov, A.; /Fermilab

    2011-03-01

    Van Kampen modes are eigen-modes of Jeans-Vlasov equation [1-3]. Their spectrum consists of continuous and, possibly, discrete parts. Onset of a discrete van Kampen mode means emergence of a coherent mode without any Landau damping; thus, even a tiny couple-bunch wake is sufficient to drive instability. Longitudinal instabilities observed at Tevatron [4], RHIC [5] and SPS [6] can be explained as loss of Landau damping (LLD), which is shown here to happen at fairly low impedances. For repulsive wakes and single-harmonic RF, LLD is found to be extremely sensitive to steepness of the bunch distribution function at small amplitudes. Based on that, a method of beam stabilization is suggested. Emergence of a discrete van Kampen mode means either loss of Landau damping or instability. Longitudinal bunch stability is analysed in weak head-tail approximation for inductive impedance and single-harmonic RF. The LLD threshold intensities are found to be rather low: for cases under study all of them do not exceed a few percent of the zero-amplitude incoherent synchrotron frequency shift, strongly decreasing for shorter bunches. Because of that, LLD can explain longitudinal instabilities happened at fairly low impedances at Tevatron [4], and possibly for RHIC [5] and SPS [6], being in that sense an alternative to the soliton explanation [5, 20]. Although LLD itself results in many cases in emergence of a mode with zero growth rate, any couple-bunch (and sometimes multi-turn) wake would drive instability for that mode, however small this wake is. LLD is similar to a loss of immune system of a living cell, when any microbe becomes fatal for it. The emerging discrete mode is normally very different from the rigid-bunch motion; thus the rigid-mode model significantly overestimates the LLD threshold. The power low of LLD predicted in Ref. [17] agrees with results of this paper. However, the numerical factor in that scaling low strongly depends on the bunch distribution function

  20. Modified bunch filling scheme for Indus-2

    International Nuclear Information System (INIS)

    Currently Indus-2 is operated with all bunches filled mode. It may be required to fill the ring with different bunch filling patterns in future as per requirements of the users and also to mitigate the problems of ion trapping and beam instabilities. In Indus-2 one can store beam current in maximum of 291 bunches. A bunch-filling scheme has been evolved in which, it is possible to fill Indus-2 with different filling patterns. In the earlier scheme, three patterns of bunch filling are proposed namely all bunches, three symmetric bunches and a single bunch. In this scheme there is problem of bunch overlapping in the buckets, if more than one bunch is extracted from the booster. In the new scheme, a formulation has been derive to avoid the overlapping of bunches. (author)

  1. CSR Interaction for a 2D Energy-Chirped Bunch on a General Orbit

    International Nuclear Information System (INIS)

    When an electron bunch with initial linear energy chirp traverses a bunch compression chicane, the bunch interacts with itself via coherent synchrotron radiation (CSR) and space charge force. The effective longitudinal CSR force for such kind of 2D bunch on a circular orbit has been analyzed earlier (1). In this paper, we present the analytical results of the effective longitudinal CSR force for a 2D energy-chirped bunch going through a general orbit, which includes the entrance and exit of a circular orbit. In particular, we will show the behavior of the force in the last bend of a chicane when the bunch is under extreme compression. This is the condition when bifurcation of bunch phase space occurs in many CSR measurements. (1) R. Li, Phys. Rev. ST Accel. Beams 11, 024401 (2008)

  2. Status of the bunch-by-bunch fast-feedback system at ANKA

    Energy Technology Data Exchange (ETDEWEB)

    Marsching, Sebastian; Hiller, Nicole; Huttel, Erhard; Judin, Vitali; Kehrer, Benjamin; Klein, Marit; Meuter, Christina; Mueller, Anke-Susanne; Nasse, Michael; Schuh, Marcel; Smale, Nigel; Streichert, Max [Karlsruhe Institute of Technology (Germany)

    2012-07-01

    At ANKA, the synchrotron light source of the Karlsruhe Institute of Technology, a vertical bunch-by-bunch fast-feedback system is being commissioned for damping multi-bunch instabilities and performing beam-dynamics studies. The ANKA synchrotron operates at a regular beam energy of 2.5 GeV while the ANKA injector operates at only 0.5 GeV. Thus, the beam injected into the synchrotron has to be ramped up in energy. Therefore, the fast-feedback system has to be able to damp instabilities over the whole energy range from 0.5 to 2.5 GeV. In this talk, we summarize the progress of the commissioning process and present studies we performed on compensating effects caused by the change of beam energy.

  3. Formation and stability of a hollow electron beam in the presence of a plasma wake field driven by an ultra-short electron bunch

    Science.gov (United States)

    Tanjia, F.; Fedele, R.; De Nicola, S.; Akhter, T.; Jovanović, D.

    2016-09-01

    A numerical investigation on the spatiotemporal evolution of an electron beam, externally injected in a plasma in the presence of a plasma wake field, is carried out. The latter is driven by an ultra-short relativistic axially-symmetric femtosecond electron bunch. We first derive a novel Poisson-like equation for the wake potential where the driving term is the ultra-short bunch density, taking suitably into account the interplay between the sharpness and high energy of the bunch. Then, we show that a channel is formed longitudinally, through the externally injected beam while experiencing the effects of the bunch-driven plasma wake field, within the context of thermal wave model. The formation of the channel seems to be a final stage of the 3D evolution of the beam. This involves the appearance of small filaments and bubbles around the longitudinal axis. The bubbles coalesce forming a relatively stable axially-symmetric hollow beam structure.

  4. Formation and stability of a hollow electron beam in the presence of a plasma wake field driven by an ultra-short electron bunch

    CERN Document Server

    Tanjia, F; De Nicola, S; Akhter, T; Jovanovic, D

    2015-01-01

    A numerical investigation on the spatiotemporal evolution of an electron beam, externally injected in a plasma in the presence of a plasma wake field, is carried out. The latter is driven by an ultra-short relativistic axially-symmetric femtosecond electron bunch. We first derive a novel Poisson-like equation for the wake potential where the driving term is the ultra-short bunch density, taking suitably into account the interplay between the sharpness and high energy of the bunch. Then, we show that a channel is formed longitudinally, through the externally injected beam while experiencing the effects of the bunch-driven plasma wake field, within the context of thermal wave model. The formation of the channel seems to be a final stage of the 3D evolution of the beam. This involves the appearance of small filaments and bubbles around the longitudinal axis. The bubbles coalesce forming a relatively stable axially-symmetric hollow beam structure.

  5. Dechirper wakefields for short bunches

    Science.gov (United States)

    Bane, Karl; Stupakov, Gennady

    2016-06-01

    In previous work (Bane and Stupakov, 2015 [1]) general expressions, valid for arbitrary bunch lengths, were derived for the wakefields of corrugated structures with flat geometry, such as is used in the RadiaBeam/LCLS dechirper. However, the bunch at the end of linac-based X-ray FELs-like the LCLS-is extremely short, and for short bunches the wakes can be considerably simplified. In this work, we first derive analytical approximations to the short-range wakes. These are generalized wakes, in the sense that their validity is not limited to a small neighborhood of the symmetry axis, but rather extends to arbitrary transverse offsets of driving and test particles. The validity of these short-bunch wakes holds not only for the corrugated structure, but rather for any flat structure whose beam-cavity interaction can be described by a surface impedance. We use these wakes to obtain, for a short bunch passing through a dechirper: estimates of the energy loss as function of gap, the transverse kick as a function of beam offset, the slice energy spread increase, and the emittance growth. In the Appendix, a more accurate derivation-than that is found in Bane and Stupakov (2015) [1]-of the arbitrary bunch length wakes is performed; we find full agreement with the earlier results, provided the bunches are short compared to the dechirper gap, which is normally the regime of interest.

  6. Effect of Fiber Esterification on Fundamental Properties of Oil Palm Empty Fruit Bunch Fiber/Poly(butylene adipate-co-terephthalate) Biocomposites

    OpenAIRE

    Mohamad Zaki AB Rahman; Wan Md Zin Wan Yunus; Nor Azowa Ibrahim; Sanaz Abdolmohammadi; Samira Siyamak

    2012-01-01

    A new class of biocomposites based on oil palm empty fruit bunch fiber and poly(butylene adipate-co-terephthalate) (PBAT), which is a biodegradable aliphatic aromatic co-polyester, were prepared using melt blending technique. The composites were prepared at various fiber contents of 10, 20, 30, 40 and 50 wt% and characterized. Chemical treatment of oil palm empty fruit bunch (EFB) fiber was successfully done by grafting succinic anhydride (SAH) onto the EFB fiber surface, and the modified fib...

  7. Bunched Beam Cooling in the Fermilab Recycler

    CERN Document Server

    Neuffer, David V; Burov, Alexey; Nagaitsev, Sergei

    2005-01-01

    Stochastic cooling with bunched beam in a linear bucket has been obtained and implemented operationally in the fermilab recycler. In this implementation the particle bunch length is much greater than the cooling system wavelengths. The simultaneous longitudinal bunching enables cooling to much smaller longitudinal emittances than the coasting beam or barrier bucket system. Characteristics and limitations of bunched beam stochastic cooling are discussed.

  8. Flat bunches in the LHC

    CERN Document Server

    Shaposhnikova, E; Baudrenghien, P; Mastoridis, T; Muller, J E; Papotti, G; Salvant, B; Timko, H; Bhat, C; Burov, A

    2014-01-01

    A high harmonic RF system which could serve multiple purposes was proposed for the LHC. Possible applications of the second harmonic RF system include beam stabilisation in the longitudinal plane in absence of wide-band longitudinal feedback and reduction of bunch peak line density. Apart from other useful features flat bunches are expected to produce less beam-induced heating below 1 GHz, the frequency region critical for some LHC equipment. The latter however can also be achieved by de-populating the bunch center. This was demonstrated during the dedicated machine development session in the LHC using RF phase modulation. In this paper the results of tests with single bunches and nominal LHC beams are presented and possible use of this technique in LHC operation is discussed.

  9. Multi-bunch Feedback Systems

    CERN Document Server

    Lonza, M

    2014-01-01

    Coupled-bunch instabilities excited by the interaction of the particle beam with its surroundings can seriously limit the performance of circular particle accelerators. These instabilities can be cured by the use of active feedback systems based on sensors capable of detecting the unwanted beam motion and actuators that apply the feedback correction to the beam. Advances in electronic technology now allow the implementation of feedback loops using programmable digital systems. Besides important advantages in terms of flexibility and reproducibility, digital systems open the way to the use of novel diagnostic tools and additional features. We first introduce coupled-bunch instabilities, analysing the equation of motion of charged particles and the different modes of oscillation of a multi-bunch beam, showing how they can be observed and measured. Different types of feedback systems will then be presented as examples of real implementations that belong to the history of multi-bunch feedback systems. The main co...

  10. STOCHASTIC COOLING FOR BUNCHED BEAMS.

    Energy Technology Data Exchange (ETDEWEB)

    BLASKIEWICZ, M.

    2005-05-16

    Problems associated with bunched beam stochastic cooling are reviewed. A longitudinal stochastic cooling system for RHIC is under construction and has been partially commissioned. The state of the system and future plans are discussed.

  11. New diagnostics and cures for coupled-bunch instabilities

    International Nuclear Information System (INIS)

    Electromagnetic interaction between a charged particle beam and its surroundings causes collective instabilities, which must be controlled if the new light sources and colliders are to meet their design goals. Control requires a combination of passive damping and fast active feedback on an unprecedented technological scale. Efficient instability diagnosis techniques are also needed for machines with large numbers of bunches. This thesis describes new methods of measuring and analyzing coupled-bunch instabilities in circular accelerators, and demonstrates the existence of a new cure. A new technique is demonstrated for simultaneous measurement of growth rates, damping rates and coherent tune shifts of all unstable coupled-bunch eigenmodes from a single 10-25-ms transient snapshot of beam motion. The technique has been used to locate and quantify beam impedance resonances at PEP-II, ALS and SPEAR. This method is faster than existing spectral scan methods by at least an order of magnitude, and has the added advantage of revealing coupled-bunch dynamics in the linear small-signal regime. A method is also presented for estimating beam impedance from multi-bunch fill shape and synchronous phase measurements. Phase space tracking of multi-bunch instabilities is introduced as a ''complete instability diagnostic.'' Digitized multi-bunch data is analyzed offline, to estimate the phase space trajectories of bunches and modes. Availability of phase space trajectories is shown to open up a variety of possibilities, including measurement of reactive impedance, and diagnosis of the fast beam-ion instability. Knowledge gained from longitudinal measurements (all made using a digital longitudinal feedback system) has been used to optimize cavity temperatures, tuner positions and feedback parameters, and also to identify sources of beam noise at the three machines. A matrix-based method is presented for analyzing the beneficial effect of bunch-to-bunch tune variation on instability

  12. SuperB Bunch-By-Bunch Feedback R&D

    Energy Technology Data Exchange (ETDEWEB)

    Drago, A.; Beretta, M.; /Frascati; Bertsche, K.; Novokhatski, A.; /SLAC; Migliorati, M.; /Rome U.

    2011-08-12

    The SuperB project has the goal to build in Italy, in the Frascati or Tor Vergata area, an asymmetric e{sup +}/e{sup -} Super Flavor Factory to achieve a peak luminosity > 10**36 cm{sup -2} s{sup -1}. The SuperB design is based on collisions with extremely low vertical emittance beams and high beam currents. A source of emittance growth comes from the bunch by bunch feedback systems producing high power correction signals to damp the beams. To limit any undesirable effect, a large R&D program is in progress, partially funded by the INFN Fifth National Scientific Committee through the SFEED (SuperB Feedback) project approved within the 2010 budget. The SuperB project [1] has the goal to build in Italy, in the Frascati or Tor Vergata area, an asymmetric e{sup +}/e{sup -} Super Flavor Factory to achieve a peak luminosity > 10**36 cm{sup -2} s{sup -1}. In the last and current years, the machine layout has been deeply modified, in particular the main rings are now shorter and an option with high currents has been foreseen. In the fig.1 the new SuperB layout is shown. From bunch-by-bunch feedback point of view, the simultaneous presence in the machine parameters, of very low emittance, of the order of 5-10 pm in the vertical plane, and very high currents, at level of 4 Ampere for the Low Energy Ring, asks for designing very carefully the bunch-by-bunch feedback systems. The parameter list is presented in Fig. 2. The bunch-by-bunch feedback design must take care of the risky and exciting challenges proposed in the SuperB specifications, but it should consider also some other important aspects: flexibility in terms of being able to cope to unexpected beam behaviours [2], [3] legacy of previous version experience [4], [5] and internal powerful diagnostics [6] as in the systems previously used in PEP-II and DAFNE [7].

  13. SuperB Bunch-By-Bunch Feedback R and D

    International Nuclear Information System (INIS)

    The SuperB project has the goal to build in Italy, in the Frascati or Tor Vergata area, an asymmetric e+/e- Super Flavor Factory to achieve a peak luminosity > 10**36 cm-2 s-1. The SuperB design is based on collisions with extremely low vertical emittance beams and high beam currents. A source of emittance growth comes from the bunch by bunch feedback systems producing high power correction signals to damp the beams. To limit any undesirable effect, a large R and D program is in progress, partially funded by the INFN Fifth National Scientific Committee through the SFEED (SuperB Feedback) project approved within the 2010 budget. The SuperB project (1) has the goal to build in Italy, in the Frascati or Tor Vergata area, an asymmetric e+/e- Super Flavor Factory to achieve a peak luminosity > 10**36 cm-2 s-1. In the last and current years, the machine layout has been deeply modified, in particular the main rings are now shorter and an option with high currents has been foreseen. In the fig.1 the new SuperB layout is shown. From bunch-by-bunch feedback point of view, the simultaneous presence in the machine parameters, of very low emittance, of the order of 5-10 pm in the vertical plane, and very high currents, at level of 4 Ampere for the Low Energy Ring, asks for designing very carefully the bunch-by-bunch feedback systems. The parameter list is presented in Fig. 2. The bunch-by-bunch feedback design must take care of the risky and exciting challenges proposed in the SuperB specifications, but it should consider also some other important aspects: flexibility in terms of being able to cope to unexpected beam behaviours (2), (3) legacy of previous version experience (4), (5) and internal powerful diagnostics (6) as in the systems previously used in PEP-II and DAFNE (7).

  14. Study of transverse coupled bunch instabilities by using non-linear Taylor maps for the Advanced Light Source (ALS)

    International Nuclear Information System (INIS)

    To study coherent bunch instabilities for the third generation light source, ALS, it is insufficient to rely on a linear map with radiation damping for the lattice to obtain the correct dynamics. We have implemented a code for transverse bunch instabilities, using a 4-dimensional map for the lattice and wake field expansions for cavities and resistive wall effects. This model has been used to study the injection process and to determine the needed performance of the proposed feedback system for the storage ring

  15. A method for measurement of the length of the order of pico-second electron bunch

    International Nuclear Information System (INIS)

    A new method is proposed for measurement of the length of pico-second electron bunch. For an electron bunch from MPG (Micro Pulse Gun), a numerical model using computing codes such as MAFIA has been constructed. And according to our own experimental condition, the model is discussed and its resolution is about 2ps. It is proved that the method is feasible for the measurement of the length of pico-second electron bunch. (authors)

  16. Effect of inoculum size on production of compost and enzymes from palm oil mill biogas sludge mixed with shredded palm empty fruit bunches and decanter cake

    Directory of Open Access Journals (Sweden)

    Tanawut Nutongkaew

    2014-06-01

    Full Text Available The effect of inoculum size on production of compost and enzymes from palm oil mill biogas sludge (POMS mixed with shredded palm empty fruit bunches (PEFB and decanter cake (DC was studied using the mixed culture LDD1 as an inoculum. Three piles of 50 kg mixture (POMS:PEFB:DC = 2:1:1 with different inoculum sizes of 0.0075% (treatment A, 0.015% (treatment B, and 0.030% (treatment C were set up. The physicochemical parameters were measured during the composting. All the compost appeared dark brown in color, crumbly, attained an ambient temperature and had the C/N ratio of 11:1 after 40 days fermentation, indicating the maturity of the compost. The optimal inoculum size was found to be 0.030% (w/w. For enzyme production, the highest carboxymethylcellulase (CMCase activity was 3.23 Unit/g substrates at 12 days incubation whereas the highest xylanase activity was 3.11 Unit/g substrates at 6 days incubation. At the end of 60 days fermentation, the compost (treatment C had a TN-P2O5 -K2O of 3.10-1.29-2.01% (dry basis. Therefore, the compost quality complied with the national compost standard set by the Ministry of Agriculture, Thailand.

  17. Studies of bunch distortion in the generation of coherent THz-radiation at the ANKA storage Ring

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Marit; Bueckle, Tobias; Fitterer, Miriam; Hofmann, Andre; Sonnad, Kiran [Universitaet Karlsruhe (Germany); Birkel, Ingrid; Huttel, Erhard; Mathis, Yves-Laurent [Forschungszentrum Karlsruhe (Germany); Mueller, Anke-Susanne [Universitaet Karlsruhe (Germany); Forschungszentrum Karlsruhe (Germany)

    2009-07-01

    In synchrotron light sources, coherent synchrotron radiation (CSR) is emitted at wavelengths comparable to and longer than the bunch length. One effect of the CSR wake field is the distortion of the bunch distribution, which increases with higher currents. In this paper the development of the calculated bunch shapes and the corresponding moments - such as the expectation value, the bunchlength, the skewness and the kurtosis - of the current distribution for varying bunch currents are studied.

  18. Studies of bunch distortion in the generation of coherent THz-radiation at the ANKA storage Ring

    International Nuclear Information System (INIS)

    In synchrotron light sources, coherent synchrotron radiation (CSR) is emitted at wavelengths comparable to and longer than the bunch length. One effect of the CSR wake field is the distortion of the bunch distribution, which increases with higher currents. In this paper the development of the calculated bunch shapes and the corresponding moments - such as the expectation value, the bunchlength, the skewness and the kurtosis - of the current distribution for varying bunch currents are studied

  19. Submicron multi-bunch BPM for CLIC

    Energy Technology Data Exchange (ETDEWEB)

    Schmickler, H.; Soby, L.; /CERN; Lunin, A.; Solyak, N.; Wendt, M.; /Fermilab

    2010-08-01

    A common-mode free cavity BPM is currently under development at Fermilab within the ILC-CLIC collaboration. This monitor will be operated in a CLIC Main Linac multi-bunch regime, and needs to provide both, high spatial and time resolution. We present the design concept, numerical analysis, investigation on tolerances and error effects, as well as simulations on the signal response applying a multi-bunch stimulus. The proposed CERN linear collider (CLIC) requires a very precise measurement of beam trajectory to preserve the low emittance when transporting the beam through the Main Linac. An energy chirp within the bunch train will be applied to measure and minimize the dispersion effects, which require high resolution (in both, time and space) beam position monitors (BPM) along the beam-line. We propose a low-Q waveguide loaded TM{sub 110} dipole mode cavity as BPM, which is complemented by a TM{sub 010} monopole mode resonator of same resonant frequency for reference signal purposes. The design is based on a well known TM{sub 110} selective mode coupling idea.

  20. Bunched black (and grouped grey) swans: Dissipative and non-dissipative models of correlated extreme fluctuations in complex geosystems

    OpenAIRE

    N. W. Watkins

    2013-01-01

    I review the hierarchy of approaches to complex systems, focusing particularly on stochastic equations. I discuss how the main models advocated by the late Benoit Mandelbrot fit into this classification, and how they continue to contribute to cross-disciplinary approaches to the increasingly important problems of correlated extreme events and unresolved scales. The ideas have broad importance, with applications ranging across science areas as diverse as the heavy tailed distributions of inten...

  1. Efficiency of feedbacks for suppression of transverse instabilities of bunched beams

    CERN Document Server

    Burov, Alexey

    2016-01-01

    Which gain and phase have to be set for a bunch-by-bunch transverse damper, and at which chromaticity it is better to stay? These questions are considered for three models: the two-particle model with possible quadrupole wake, the author's Nested Head-Tail Vlasov solver with a broadband impedance, and the same with the LHC impedance model.

  2. VELOCITY BUNCHING OF HIGH-BRIGHTNESS ELECTRON BEAMS

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, S G; Musumeci, P; Rosenzweig, J B; Brown, W J; England, R J; Ferrario, M; Jacob, J S; Thompson, M C; Travish, G; Tremaine, A M; Yoder, R

    2004-10-15

    Velocity bunching has been recently proposed as a tool for compressing electron beam pulses in modern high brightness photoinjector sources. This tool is familiar from earlier schemes implemented for bunching dc electron sources, but presents peculiar challenges when applied to high current, low emittance beams from photoinjectors. The main difficulty foreseen is control of emittance oscillations in the beam in this scheme, which can be naturally considered as an extension of the emittance compensation process at moderate energies. This paper presents two scenarios in which velocity bunching, combined with emittance control, is to play a role in nascent projects. The first is termed ballistic bunching, where the changing of relative particle velocities and positions occur in distinct regions, a short high gradient linac, and a drift length. This scenario is discussed in the context of the proposed ORION photoinjector. Simulations are used to explore the relationship between the degree of bunching, and the emittance compensation process. Experimental measurements performed at the UCLA Neptune Laboratory of the surprisingly robust bunching process, as well as accompanying deleterious transverse effects, are presented. An unanticipated mechanism for emittance growth in bends for highly momentum chirped beam was identified and studied in these experiments. The second scenario may be designated as phase space rotation, and corresponds closely to the recent proposal of Ferrario and Serafini. Its implementation for the compression of the electron beam pulse length in the PLEIADES inverse Compton scattering (ICS) experiment at LLNL is discussed. It is shown in simulations that optimum compression may be obtained by manipulation of the phases in low gradient traveling wave accelerator sections. Measurements of the bunching and emittance control achieved in such an implementation at PLEIADES, as well as aspects of the use of velocity-bunched beam directly in ICS experiments

  3. Coherent radiation by short bunch electron beam

    International Nuclear Information System (INIS)

    The electron beam which is accelerated with a linear accelerator forms the bunch of which the length in advancing direction is several millimeter. The radiation in far infrared region and transition radiation emitted from it are the coherent radiation, in which the phase of the radiation components from many electrons are uniform. Consequently, the intensity increases remarkably. By using this, the research on the properties of transition radiation of long wavelength and Cherenkov radiation which were unknown so far because those are weak was carried out. The radiation like this is not only powerful light source, but also it can be utilized to measure the shape of the bunch of accelerated particles. The coherent effect and the intensity of coherent radiation are explained. The spectra and the intensity distribution, the interference of coherent light, the properties of transition radiation, the formation layer of Cherenkov radiation from finite tracks and so on are reported. The measurement of the shape of bunch was carried out, and line-shaped beam and laterally extended beam are explained. The application as light source is reported. (K.I.)

  4. Self-bunching electron guns

    CERN Document Server

    Mako, F; Weilhammer, Peter

    1999-01-01

    We report on three electron gun projects that are aimed at power tube and injector applications. The purpose of the work is to develop robust electron guns which produce self-bunched, high-current-density beams. We have demonstrated cold emission, long life, and tolerance to contamination. The cold emission process is based on secondary electron emission. FMT has studied this resonant bunching process which gives rise to high current densities (0.01-5 kA/cm/sup 2/), high charge bunches (up to 100 nC/bunch), and short pulses (1-100 ps) for frequencies from 1 to 12 GHz. The beam pulse width is nominally ~5% of the RF period. The first project is the L-Band Micro-Pulse Gun (MPG). Measurements show ~40 ps long microbunches at ~20 A/cm/sup 2/ without contamination due to air exposure. Lifetime testing has been carried out for about 18 months operating at 1.25 GHz for almost 24 hours per day at a repetition rate of 300 Hz and 5 mu s-long macro- pulses. About 5.8*10/sup 13/ micro-bunches or 62,000 coulombs have pass...

  5. Sub-picosecond electron bunch length measurement

    International Nuclear Information System (INIS)

    A subpicosecond electron bunch length measuring system has been developed at the SUNSHINE facility. The method is based on an autocorrelation technique in the frequency domain utilizing the coherent radiation emitted from the electron bunch at wavelengths equal and longer than the bunch length. The radiation spectrum is the Fourier transform of the electron bunch distribution and measuring this spectrum in a far-infrared Michelson interferometer allows the determination of the bunch length down to the femto-second regime. The experimental setup and measurement of subpicosecond electron pulses including possible improvements to maximize the bunch information available from an interferogram will be described

  6. Coulomb-mediated electron bunching in tunneling through coupled quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Kiesslich, G. [Institut fuer Theoretische Physik, Technische Universitaet Berlin, 10623 Berlin (Germany); School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom); Schoell, E. [Institut fuer Theoretische Physik, Technische Universitaet Berlin, 10623 Berlin (Germany); Hohls, F.; Haug, R.J. [Institut fuer Festkoerperphysik, Leibniz Universitaet Hannover, 30167 Hannover (Germany)

    2008-07-01

    The recent observation of super-Poissonian shot noise in the tunneling current through two layers of selfassembled quantum dots is analyzed and discussed in terms of a sequential tunneling model for a single weakly coupled quantum dot stack. We demonstrate that the phenomenon of bunching in the electron transfer can be explained by the sole effect of Coulomb interaction between electrons inside the stack. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. On the preservation of single- and multi-bunch emittance in linear accelerators

    International Nuclear Information System (INIS)

    This document is concentrated on the investigation of the dynamics of a particle beam in a linear accelerator. We numerically simulate a number of effects and evaluate the severity of their impact on the beam. Furthermore, we examine the applicability of several correction techniques aiming at the suppression or correction of the effects diluting the beam emittance. First, there is the issue of single-bunch dynamics : we see that wake field effects and dispersive errors can cause a significant emittance growth. Secondly, long range dipole wakes and dispersive effects arising from the energy spread between different bunches will cause relative offsets between the individual bunches and likewise result in emittance growth. Finally, we observe interactions between the single-bunch and multi-bunch dynamics in a bunch train, which further aggravate these effects. The corrective measures against emittance growth are first tested with respect to individual effects relating to issues of single- or multi-bunch dynamics. Later, these different correction techniques are joined to one machine tuning procedure that will be applied in order to achieve good emittance preservation for operation of the accelerator with a full beam consisting of the full number of bunches. The performance of this procedure is tested in simulations of the combined single- and multi-bunch dynamics. Finally, tolerances on the machine alignment as well as machine and beam parameters are established. (orig.)

  8. Creation and storage of long and flat bunches in the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Damerau, H.

    2005-09-01

    To maximize the luminosity of the Large Hadron Collider (LHC), the collision of particle bunches with a uniform longitudinal particle density is considered for a future upgrade. The benefits of such bunches and their generation by means of special longitudinal beam manipulations are presented in this report. Three possible options are analyzed with respect to their potential luminosity gain at the beam-beam limit: short rectangular bunches held by radio frequency (RF) harmonics using multiples of the nominal RF frequency of 400.8 MHz, long and flat bunches held by multiples of 40.08 MHz, and so-called superbunches, confined by barrier buckets. The comparison of the three different approaches shows that flat bunches, with an intermediate bunch length of the order of several meters, are capable of producing a comparable luminosity to superbunches, while avoiding most of their inherent disadvantages. Possible schemes to create the bunches with uniform line density are studied and a longitudinal manipulation to combine a batch of ordinary bunches into a long and flat bunch is proposed. These RF gymnastics are based on well-proven techniques such as batch compression and bunch pair merging. Their advantages and disadvantages, including optimization with respect to degradation of the longitudinal particle density, are discussed in detail. Special attention is paid to the investigation of collective effects due to the large line charge density and the influence of the beam on the RF installation is also studied. (Orig.)

  9. Creation and storage of long and flat bunches in the LHC

    International Nuclear Information System (INIS)

    To maximize the luminosity of the Large Hadron Collider (LHC), the collision of particle bunches with a uniform longitudinal particle density is considered for a future upgrade. The benefits of such bunches and their generation by means of special longitudinal beam manipulations are presented in this report. Three possible options are analyzed with respect to their potential luminosity gain at the beam-beam limit: short rectangular bunches held by radio frequency (RF) harmonics using multiples of the nominal RF frequency of 400.8 MHz, long and flat bunches held by multiples of 40.08 MHz, and so-called superbunches, confined by barrier buckets. The comparison of the three different approaches shows that flat bunches, with an intermediate bunch length of the order of several meters, are capable of producing a comparable luminosity to superbunches, while avoiding most of their inherent disadvantages. Possible schemes to create the bunches with uniform line density are studied and a longitudinal manipulation to combine a batch of ordinary bunches into a long and flat bunch is proposed. These RF gymnastics are based on well-proven techniques such as batch compression and bunch pair merging. Their advantages and disadvantages, including optimization with respect to degradation of the longitudinal particle density, are discussed in detail. Special attention is paid to the investigation of collective effects due to the large line charge density and the influence of the beam on the RF installation is also studied. (Orig.)

  10. Transverse multibunch modes for non-rigid bunches, including mode coupling

    Energy Technology Data Exchange (ETDEWEB)

    Berg, J.S.; Ruth, R.D. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1996-08-01

    A method for computing transverse multibunch growth rates and frequency shifts in rings, which has been described previously, is applied to the PEP-II B factory. The method allows multibunch modes with different internal-bunch oscillation modes to couple to one another, similar to single-bunch mode coupling. Including coupling between the multibunch modes gives effects similar to those seen in single-bunch mode coupling. These effects occur at currents that are lower than the single-bunch mode coupling threshold. (author)

  11. Transverse multibunch modes for non-rigid bunches, including mode coupling

    International Nuclear Information System (INIS)

    A method for computing transverse multibunch growth rates and frequency shifts in rings, which has been described previously, is applied to the PEP-II B factory. The method allows multibunch modes with different internal-bunch oscillation modes to couple to one another, similar to single-bunch mode coupling. Including coupling between the multibunch modes gives effects similar to those seen in single-bunch mode coupling. These effects occur at currents that are lower than the single-bunch mode coupling threshold

  12. Self-bunching electron guns

    International Nuclear Information System (INIS)

    We report on three electron gun projects that are aimed at power tube and injector applications. The purpose of the work is to develop robust electron guns which produce self-bunched, high-current-density beams. We have demonstrated cold emission, long life, and tolerance to contamination. The cold emission process is based on secondary electron emission. FMT has studied this resonant bunching process which gives rise to high current densities (0.01-5 kA/cm2), high charge bunches (up to 100 nC/bunch), and short pulses (1-100 ps) for frequencies from 1 to 12 GHz. The beam pulse width is nominally ∼5% of the rf period. The first project is the L-Band Micro-Pulse Gun (MPG). Measurements show ∼40 ps long micro-bunches at ∼20 A/cm2 without contamination due to air exposure. Lifetime testing has been carried out for about 18 months operating at 1.25 GHz for almost 24 hours per day at a repetition rate of 300 Hz and 5 μs-long macro-pulses. About 5.8x1013 micro-bunches or ∼62,000 coulombs have passed through this gun and it is still working fine. The second project, the S-Band MPG†, is now operational. It is functioning at a frequency of 2.85 GHz, a repetition rate of 30 Hz, with a 2 μs-long macro-pulse. It produces about 150 A/cm2. The third project involves the construction of a 34.2 GHz frequency-multiplied source driven by an X-Band MPG. Analytical work has been carried out on this device, and we are ready to proceed with design, fabrication, and testing

  13. Methods For Electron Bunch Measurement With Resolution Of The Order Of 1 Fs And 1 Nm

    CERN Document Server

    Tron, A M

    2004-01-01

    Methods for bunch length and shape monitoring with femtosecond resolution by means of time converting photochronography of the bunch radiation in the range of visible light using photoelectron camera of new principle of its operation, and for monitoring the transverse bunch size, based on new beam cross section wire scanner technique where the depth of electron escapement being not more than 1 nm is used, are described. Main limitation, caused by space charge effect, is considered.

  14. Asynchronous accelerator with RFQ injection for active longitudinal compression of accelerated bunches

    OpenAIRE

    Tumanyan, A. R.; Martirosyan, Yu. L.; Nikhogosyan, V. C.; Akopov, N. Z.; Guiragossian, Z. G.; Martirosov, R. M.; Akopov, Z. N.

    2000-01-01

    An asynchronous accelerator is described, in which the principle of its operation permits the active longitudinal bunch compression of accelerated proton beams, to overcome the space charge limitation effects of intense bunches. It is shown that accelerated bunches from an RFQ linac can be adapted for Asynchronac injection for a multiple of choices in the acceleration frequencies of the RFQ and the Asynchronac. The offered new type of accelerator system is especially suitable to accelerate pr...

  15. Beam dynamics performances and applications of a low-energy electron-beam magnetic bunch compressor

    OpenAIRE

    Prokop, C. R.; Piot, P; Carlsten, B. E.; Church, M.

    2013-01-01

    Many front-end applications of electron linear accelerators rely on the production of temporally-compressed bunches. The shortening of electron bunches is often realized with magnetic bunch compressors located in high-energy sections of accelerators. Magnetic compression is subject to collective effects including space charge and self interaction via coherent synchrotron radiation. In this paper we explore the application of magnetic compression to low-energy ($\\sim 40$ MeV), high-charge (nC)...

  16. Stochastic cooling of bunched beams

    International Nuclear Information System (INIS)

    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

  17. Feedback system for suppression of the beam self-bunching in the U-70 accelerators

    International Nuclear Information System (INIS)

    Slow removal of proton beams from the U-70 proton synchrotron is complicated by the beam self-bunching effect, circulating on the magnetic field plateau. The effect is caused by the particles interaction with the operating 40-type oscillations of the disconnected HF-resonators, The system for suppression of this instability through the feedback channel (F C) by the beam, closed through one of the HF-resonators is proposed. Th principles of building the system are discussed and choice of its working parameters is explained. The results of the circuit-engineering modeling of the F C electrical scheme are presented. The proposed system is a version for technical solution of the problem on the beam self-bunching, considered within the frames of the program on the U-70 accelerator modernization

  18. Beam dynamics performances and applications of a low-energy electron-beam magnetic bunch compressor

    Energy Technology Data Exchange (ETDEWEB)

    Prokop, C.R., E-mail: cprokop@gmail.com [Northern Illinois Center for Accelerator and Detector Development and Department of Physics, Northern Illinois University, DeKalb, IL 60115 (United States); Piot, P. [Northern Illinois Center for Accelerator and Detector Development and Department of Physics, Northern Illinois University, DeKalb, IL 60115 (United States); Accelerator Physics Center, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States); Carlsten, B.E. [Acceleration Operations and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Church, M. [Accelerator Division, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States)

    2013-08-11

    Many front-end applications of electron linear accelerators rely on the production of temporally compressed bunches. The shortening of electron bunches is often realized with magnetic bunch compressors located in high-energy sections of accelerators. Magnetic compression is subject to collective effects including space charge and self interaction via coherent synchrotron radiation. In this paper we explore the application of magnetic compression to low-energy (∼40MeV), high-charge (nC) electron bunches with low normalized transverse emittances (<5μm). -- Author-Highlights: • We explore the viability of bunch compression at low energies and high charges. • Simulations for bunch charges ranging from 20-pC to 3.2-nC are presented. • Performed in the context of Fermilab's Advanced Superconducting Test Accelerator. • Codes including space charge and coherent synchrotron radiation are benchmarked. • Under-compression and low charges greatly reduced emittance growth.

  19. Beam dynamics performances and applications of a low-energy electron-beam magnetic bunch compressor

    International Nuclear Information System (INIS)

    Many front-end applications of electron linear accelerators rely on the production of temporally compressed bunches. The shortening of electron bunches is often realized with magnetic bunch compressors located in high-energy sections of accelerators. Magnetic compression is subject to collective effects including space charge and self interaction via coherent synchrotron radiation. In this paper we explore the application of magnetic compression to low-energy (∼40MeV), high-charge (nC) electron bunches with low normalized transverse emittances (<5μm). -- Author-Highlights: • We explore the viability of bunch compression at low energies and high charges. • Simulations for bunch charges ranging from 20-pC to 3.2-nC are presented. • Performed in the context of Fermilab's Advanced Superconducting Test Accelerator. • Codes including space charge and coherent synchrotron radiation are benchmarked. • Under-compression and low charges greatly reduced emittance growth

  20. Beam loading compensation for acceleration of multi-bunch electron beam train

    Science.gov (United States)

    Liu, Shengguang; Fukuda, Masafumi; Araki, Sakae; Terunuma, Nobuhiro; Urakawa, Junji; Hirano, Koichiro; Sasao, Noboru

    2008-01-01

    The laser undulator compact X-ray source (LUCX) is a test bench used with the compact, high-brightness X-ray generator at KEK (High Energy Accelerator Research Organization). Our group is conducting experiments with LUCX to demonstrate the possibility of K-edge digital subtraction angiography, based on Compton scattering. One of the challenging problems is to generate high-brightness multi-bunch electron beams to compensate for the energy difference arising from the beam loading effect. In this paper we calculate the transient beam loading voltage and energy gain from the RF field in the gun and accelerating tube for a multi-bunch train. To do so we consider the process by which the RF field builds up in the gun and accelerating tube, and the special shape of the RF pulse. We generate and accelerate 100 bunches with a 50 nC electron bunch train, effectively compensating for the beam loading effect by adjusting the injection timing. Using a beam position monitor (BPM) and optical transition radiation (OTR) system, we measure the electron beam energy bunch by bunch. The average energy of a 100-bunch train is 40.5 MeV and the maximum energy difference from bunch to bunch is 0.26 MeV.

  1. Beam loading compensation for acceleration of multi-bunch electron beam train

    International Nuclear Information System (INIS)

    The laser undulator compact X-ray source (LUCX) is a test bench used with the compact, high-brightness X-ray generator at KEK (High Energy Accelerator Research Organization). Our group is conducting experiments with LUCX to demonstrate the possibility of K-edge digital subtraction angiography, based on Compton scattering. One of the challenging problems is to generate high-brightness multi-bunch electron beams to compensate for the energy difference arising from the beam loading effect. In this paper we calculate the transient beam loading voltage and energy gain from the RF field in the gun and accelerating tube for a multi-bunch train. To do so we consider the process by which the RF field builds up in the gun and accelerating tube, and the special shape of the RF pulse. We generate and accelerate 100 bunches with a 50 nC electron bunch train, effectively compensating for the beam loading effect by adjusting the injection timing. Using a beam position monitor (BPM) and optical transition radiation (OTR) system, we measure the electron beam energy bunch by bunch. The average energy of a 100-bunch train is 40.5 MeV and the maximum energy difference from bunch to bunch is 0.26 MeV

  2. Beam dynamics performances and applications of a low-energy electron-beam magnetic bunch compressor

    CERN Document Server

    Prokop, C R; Carlsten, B E; Church, M

    2013-01-01

    Many front-end applications of electron linear accelerators rely on the production of temporally-compressed bunches. The shortening of electron bunches is often realized with magnetic bunch compressors located in high-energy sections of accelerators. Magnetic compression is subject to collective effects including space charge and self interaction via coherent synchrotron radiation. In this paper we explore the application of magnetic compression to low-energy ($\\sim 40$ MeV), high-charge (nC) electron bunches with low normalized transverse emittances ($< 5$ $\\mu$m).

  3. Running excitation of blades bunches

    Czech Academy of Sciences Publication Activity Database

    Půst, Ladislav; Pešek, Luděk

    Praha: Institute of Thermomechanics AS CR, 2014 - (Zolotarev, I.; Pešek, L.), s. 45-52 ISBN 978-80-87012-54-3. [DYMAMESI 2014. Praha (CZ), 25.11.2014-26.11.2014] Institutional support: RVO:61388998 Keywords : damping * dry friction * five-blades-bunch * delayed harmonic excitation Subject RIV: BI - Acoustics

  4. Bunch length measurements in the VUV storage ring

    International Nuclear Information System (INIS)

    Measurements of the bunch length have been made as part of a study of current-dependent phenomena to provide a complete characterization of the VUV ring. Scaling laws have been put forth for the anomalous bunch lengthening with current which is generally observed in storage rings. However, there is no complete theory of the lengthening phenomenon and it is of great interest to compare the behavior of existing machines to the scaling laws. In addition, high peak currents are sought both for damping rings for linear colliders and for free-electron laser drivers and might be achieved through low-momentum compaction lattices. Finally since the bunch lengthening depends on the vacuum chamber. The accepted scaling law of bunch length with current contains the RF voltage, electron energy and momentum compaction. The VUV ring was particularly interesting for such measurements because one could separately and easily vary both the electron energy and the momentum compaction. Although the ring is injected at full energy (750 MeV) the authors have had extensive experience running the ring at low-energy (as low as 80 MeV) for the TOK project. In the following they discuss their measurement technique. The low current bunch length in operational conditions is on the order of 170 psec (σ), i.e., comparable to or longer than the vacuum pipe's smallest dimension, and allows a simple measurement. They present data of bunch length versus current (up to 500 mA in a single bunch), varying electron energy and momentum compaction. Finally, a fit of the data with the Chao-Gareyte model is discussed

  5. Bunch compressor for high-current single bunch electron linear accelerator

    International Nuclear Information System (INIS)

    A bunch compressor with four dipole magnet has been installed and tested on the IRIS-Osaka single bunch electron linear accelerator. The single bunch with a full length of 40 ps is compressed into 12 ps, whereas the bunch length of 16 ps in FWHM is compressed into 9.5 ps. The maximum compression rate is estimated to be about 30% for the single bunch with the charge of 10-40 nC

  6. Single Bunch Longitudinal Instability in the CERN SPS

    CERN Document Server

    Lasheen, Alexandre; Hancock, Steven; Radvilas, Edgaras; Roggen, Toon; Shaposhnikova, Elena

    2016-01-01

    The longitudinal single bunch instability observed in the SPS leads to uncontrolled emittance blow-up and limits the quality of high intensity beams required for the High Luminosity LHC and AWAKE projects at CERN. The present SPS impedance model developed from a thorough survey of machine elements was used in macro-particle simulations (with the code BLonD) of the bunch behavior through the acceleration cycle. Comparison of simulations with measurements of the synchrotron frequency shift, performed on the SPS flat bottom to probe the impedance, show a reasonable agreement. During extensive experimental studies various beam and machine parameters (bunch intensity, longitudinal emittance, RF voltage, with single and double RF systems) were scanned in order to further benchmark the SPS impedance model with measurements and to better understand the mechanism behind the instability. It was found that the dependence of instability threshold on longitudinal emittance and beam energy has an unexpected non-monotonic b...

  7. Laser induced bunch lengthening on the ACO storage ring FEL

    Science.gov (United States)

    Robinson, K. E.; Madey, J. M. J.; Deacon, D. A. G.; Velghe, M. F.

    1983-03-01

    The experimental procedures and data obtained during a study of the laser-induced change in the electron bunch length are reported for trials with a free-electron laser (FEL). Bunch lengthening is thought to play a critical role in the efficiency and power output of an FEL. The experimental apparatus consisted of an external laser, an undulator ring, and a nonisochronous storage ring. Synchrotron light in the storage ring was measured by a photodiode, and bunch length changes were monitored by tuning the receiver mode to a harmonic of the orbit frequency. A Gaussian electron pulse shape was assumed, together with a Gaussian envelope for the Fourier transform, which was proven in a previous experiment. The power spectra of the photodiode were modeled analytically. It was found that high current conditions alter the electron excitation and require further theoretical modeling.

  8. Studies of longitudinal profile of electron bunches and impedance measurements at Indus-2 synchrotron radiation source

    Science.gov (United States)

    Garg, Akash Deep; Yadav, S.; Kumar, Mukesh; Shrivastava, B. B.; Karnewar, A. K.; Ojha, A.; Puntambekar, T. A.

    2016-04-01

    Indus-2 is a 3rd generation synchrotron radiation source at the Raja Ramanna Centre for Advanced Technology (RRCAT) in India. We study the longitudinal profile of electrons in Indus-2 by using dual sweep synchroscan streak camera at visible diagnostic beamline. In this paper, the longitudinal profiles of electron bunch are analyzed by filling beam current in a single bunch mode. These studies are carried at injection energy (550 MeV) and at ramped beam energy (2.5 GeV). The effects of the wakefield generated interactions between the circulating electrons and the surrounding vacuum chamber are analyzed in terms of measured effects on longitudinal beam distribution. The impedance of the storage ring is obtained by fitting the solutions of Haissinski equation to the measured bunch lengthening with different impedance models. The impedance of storage ring obtained by a series R+L impedance model indicates a resistance (R) of 1350±125 Ω, an inductance (L) of 180±25 nH and broadband impedance of 2.69 Ω. These results are also compared with the values obtained from measured synchronous phase advancing and scaling laws. These studies are very useful in better understanding and control of the electromagnetic interactions.

  9. CSR instability in a Bunch Compressor

    International Nuclear Information System (INIS)

    The coherent synchrotron radiation of a bunch in a bunch compressor may lead to the microwave instability producing longitudinal modulation of the bunch with wavelengths small compared to the bunch length. It can also be a source of an undesirable emittance growth in the compressor. We derive and analyze the equation that describes linear evolution of the microwave modulation taking into account incoherent energy spread and finite emittance of the beam. Numerical solution of this equation for the LCLS bunch compressor gives the amplification factor for different wavelengths of the beam microbunching

  10. High-sensitivity bunch charge monitor

    International Nuclear Information System (INIS)

    Conceptual design of a high-sensitivity bunch charge monitor is presented. The device operates with short, spaced bunches. For the optimal performance, the bunch duration should be less than 10 ns and bunch spacing should be more than 100 ns. Sensitivity of the monitor is near 10 V per nanocoulomb. The equivalent scheme and the output signal shape are also presented. Such a kind of monitor seems to be promising for bunch charge measurements of the beams like those in the TESLA or ILC projects

  11. High-sensitivity bunch charge monitor

    Science.gov (United States)

    Lebedev, N. I.; Fateev, A. A.

    2008-12-01

    The conceptual design for a high-sensitivity bunch charge monitor is presented. The device operates with short, spaced bunches. For optimal performance, the bunch duration should be less than 10 ns and bunch spacing should be more than 100 ns. Sensitivity of the monitor is close to 10 V per nanocoulomb. The equivalent scheme and the output signal shape are also presented. Such a monitor seems to be promising for the bunch charge measurements of beams like those in TESLA or ILC projects.

  12. Coherent Synchrotron Radiation and Bunch Stability in a Compact Storage Ring

    International Nuclear Information System (INIS)

    We examine the effect of the collective force due to coherent synchrotron radiation (CSR) in an electron storage ring with small bending radius. In a computation based on time-domain integration of the nonlinear Vlasov equation, we find the threshold current for a longitudinal microwave instability induced by CSR alone. The model accounts for suppression of radiation at long wavelengths due to shielding by the vacuum chamber. In a calculation just above threshold, small ripples in the charge distribution build up over a fraction of a synchrotron period, but then die out to yield a relatively smooth but altered distribution with eventual oscillations in bunch length. The instability evolves from small noise on an initial smooth bunch of rms length much greater than the shielding cutoff

  13. Coherent synchrotron radiation and bunch stability in a compact storage ring

    Science.gov (United States)

    Venturini, Marco; Warnock, Robert; Ruth, Ronald; Ellison, James A.

    2005-01-01

    We examine the effect of the collective force due to coherent synchrotron radiation (CSR) in an electron storage ring with small bending radius. In a computation based on time-domain integration of the nonlinear Vlasov equation, we find the threshold current for a longitudinal microwave instability induced by CSR alone. The model accounts for suppression of radiation at long wavelengths due to shielding by the vacuum chamber. In a calculation just above threshold, small ripples in the charge distribution build up over a fraction of a synchrotron period, but then die out to yield a relatively smooth but altered distribution with eventual oscillations in bunch length. The instability evolves from small noise on an initial smooth bunch of rms length much greater than the shielding cutoff.

  14. The Effect of Fiber Bleaching Treatment on the Properties of Poly(lactic acid)/Oil Palm Empty Fruit Bunch Fiber Composites

    OpenAIRE

    Marwah Rayung; Nor Azowa Ibrahim; Norhazlin Zainuddin; Wan Zuhainis Saad; Nur Inani Abdul Razak; Buong Woei Chieng

    2014-01-01

    In this work, biodegradable composites from poly(lactic acid) (PLA) and oil palm empty fruit bunch (OPEFB) fiber were prepared by melt blending method. Prior to mixing, the fiber was modified through bleaching treatment using hydrogen peroxide. Bleached fiber composite showed an improvement in mechanical properties as compared to untreated fiber composite due to the enhanced fiber/matrix interfacial adhesion. Interestingly, fiber bleaching treatment also improved the physical appearance of th...

  15. The Effect of Glycerol and Oil Palm Empty Fruit Bunches Microcrystalline Cellulose Loading on Tensile Properties and Water Absorption of Cassava Starch Composite

    OpenAIRE

    Hairani, Novie; Harahap, Hamidah; Herawan, Tjahjono; Taslim

    2015-01-01

    The development and the utilization of starch as a packaging material which is eco-friendly, renewable and biodegradable have increased in recent years. In this study, cassava starch was modified into composites by adding glycerol as plasticizer and oil palm empty fruit bunches (OPEFB) microcrystalline cellulose (MCC) as fillers. The MCC was prepared via the pulping process of OPEFB and acid hydrolysis. The composites were cast into films by varying glycerol and MCC compositions. The effec...

  16. SUCCESSFUL BUNCHED BEAM STOCHASTIC COOLING IN RHIC.

    Energy Technology Data Exchange (ETDEWEB)

    BRENNAN, J.M.; BLASKIEWICZ, M.; SEVERINO, F.

    2006-06-23

    We report on a successful test of bunch-beam stochastic cooling in RHIC at 100 GeV. The cooling system is designed for heavy ions but was tested in the recent RHIC run which operated only with polarized protons. To make an analog of the ion beam a special bunch was prepared with very low intensity. This bunch had {approx}1.5 x 10{sup 9} protons, while the other 100 bunches contained {approx}1.2 x 10{sup 11} protons each. With this bunch a cooling time on the order 1 hour was observed through shortening of the bunch length and increase in the peak bunch current, together with a narrowing of the spectral line width of the Scottky power at 4 GHz. The low level signal processing electronics and the isolated-frequency kicker cavities are described.

  17. Multi-Bunch Beam Dynamics Studies for the European XFEL

    CERN Document Server

    Baboi, N

    2004-01-01

    In the X-ray free electron laser planned to be built at DESY (TESLA XFEL) the acceleration of the electron bunches will be made with 9-cell superconducting cavities. These cavities have been initially developed within the TESLA linear collider study. The impact of the higher order modes (HOM) has been shown to be within the acceptable beam dynamics limits for the collider. For the XFEL the dynamics is relaxed from point of view of multi-bunch effects (e.g. shorter length, higher emittance). However the lower energy and different time structure of the beam make the study of the HOM effects in the XFEL linac necessary. Multi-bunch beam dynamics studies are ongoing. The results of the HOM measurements at the TESLA Test Facility are used. Several options for the beam structure, as necessary for various applications, are studied. The results will be discussed.

  18. Generation of ultra-short relativistic-electron-bunch by a laser wakefield

    NARCIS (Netherlands)

    Khachatryan, A.G.; Boller, K.-J.; Goor, van F.A.

    2003-01-01

    The possibility of the generation of an ultra-short (about one micron long) relativistic (up to a few GeVs) electron-bunch in a moderately nonlinear laser wakefield excited in an underdense plasma by an intense laser pulse is investigated. The ultra-short bunch is formed by trapping, effective compr

  19. An analytical description of longitudinal phase space distortions in magnetic bunch compressors

    International Nuclear Information System (INIS)

    In this paper we consider a possible mechanism of strong distortions of longitudinal phase space due to collective effects in an electron bunch passing a bunch compressor. Analytical expressions are derived for the case of a linear compression. Estimates for the TESLA Test Facility at DESY are presented

  20. Advanced Bunching Scheme at REGAE

    OpenAIRE

    Zeitler, Benno; Floettmann, Klaus; Gruener, Florian

    2015-01-01

    The field of laser wakefield acceleration offers very high accelerating gradients. To combine the university research on this topic with the expertise of a large and well-established accelerator facility, the LAOLA Collaboration was formed between DESY and the University of Hamburg. One of the campaigns pursued within this framework is the external injection of an electron bunch from a conventional gun into a laser-driven plasma wakefield, which is a promising path towards increased control o...

  1. The NLC L-Band Bunch Compressor

    International Nuclear Information System (INIS)

    The first stage bunch compressor in the NLC injector complex compresses the e+/e- beams from a bunch length of 5 mm rms to 0.5 mm rms at the beam energy of 2 GeV. To obtain this compression ratio, the compressor rf section operates with an rf frequency of 1.4 GHz and a voltage of about 140 MV while a magnetic wiggler is used to generate an R56 = 0.5 m. The bunch compressor is designed to operate with a beam from the damping ring that has a bunch spacing slew of 20ps across the bunch train due to the transient loading in the damping rings. The compressor RF section is required to produce a specific energy profile along the bunch train so that the bunch spacing can be corrected in the compressor bending section. Further, the 1-amp beam heavily loads the compressor linac and beam loading compensation is essential to prevent a phase variation along the bunch train in the downstream linacs. In this paper, we will present simulation results of the beam loading compensation using a ΔT scheme assuming various initial bunch spacing arrangements. We will study the impact of the different compressor energy profiles on the beam energy, energy spread, and bunch length at the IP

  2. The Effect of Fiber Bleaching Treatment on the Properties of Poly(lactic acid/Oil Palm Empty Fruit Bunch Fiber Composites

    Directory of Open Access Journals (Sweden)

    Marwah Rayung

    2014-08-01

    Full Text Available In this work, biodegradable composites from poly(lactic acid (PLA and oil palm empty fruit bunch (OPEFB fiber were prepared by melt blending method. Prior to mixing, the fiber was modified through bleaching treatment using hydrogen peroxide. Bleached fiber composite showed an improvement in mechanical properties as compared to untreated fiber composite due to the enhanced fiber/matrix interfacial adhesion. Interestingly, fiber bleaching treatment also improved the physical appearance of the composite. The study was extended by blending the composites with commercially available masterbatch colorant.

  3. The effect of fiber bleaching treatment on the properties of poly(lactic acid)/oil palm empty fruit bunch fiber composites.

    Science.gov (United States)

    Rayung, Marwah; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Saad, Wan Zuhainis; Razak, Nur Inani Abdul; Chieng, Buong Woei

    2014-01-01

    In this work, biodegradable composites from poly(lactic acid) (PLA) and oil palm empty fruit bunch (OPEFB) fiber were prepared by melt blending method. Prior to mixing, the fiber was modified through bleaching treatment using hydrogen peroxide. Bleached fiber composite showed an improvement in mechanical properties as compared to untreated fiber composite due to the enhanced fiber/matrix interfacial adhesion. Interestingly, fiber bleaching treatment also improved the physical appearance of the composite. The study was extended by blending the composites with commercially available masterbatch colorant. PMID:25153628

  4. The Effect of Fiber Bleaching Treatment on the Properties of Poly(lactic acid)/Oil Palm Empty Fruit Bunch Fiber Composites

    Science.gov (United States)

    Rayung, Marwah; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Saad, Wan Zuhainis; Razak, Nur Inani Abdul; Chieng, Buong Woei

    2014-01-01

    In this work, biodegradable composites from poly(lactic acid) (PLA) and oil palm empty fruit bunch (OPEFB) fiber were prepared by melt blending method. Prior to mixing, the fiber was modified through bleaching treatment using hydrogen peroxide. Bleached fiber composite showed an improvement in mechanical properties as compared to untreated fiber composite due to the enhanced fiber/matrix interfacial adhesion. Interestingly, fiber bleaching treatment also improved the physical appearance of the composite. The study was extended by blending the composites with commercially available masterbatch colorant. PMID:25153628

  5. MICRO-BUNCHING OF THE AGS SLOW EXTRACTED BEAM FOR A RARE KAON DECAY SEARCH.

    Energy Technology Data Exchange (ETDEWEB)

    GLENN,J.; SIVERTZ,M.; CHIANG,I.; LAZARUS,D.; KOSCIELNIAK,S.

    2001-06-18

    The AGS Slow Extracted Beam (SEB) must be chopped with 250 ps bursts every 40 ns to permit time-of-flight (ToF) measurement of the secondary K{sup 0} beam. Standard techniques to produce this level of bunching would require excessive rf voltage, thus we have developed a ''Micro-Bunching'' technique of extracting the beam as it is forced between empty rf buckets. A specification of the required rf system will be given. Four-dimensional model simulations of particle dynamics for the planned rf and extraction systems will be shown. Simulations of previous tests along with the test measurements are also presented. Measurement of tight bunching requires dedicated instrumentation. The design of a detector system to measure bunch widths and the extinction factor between bunches will be given; considerations include the various particles produced and transported, timing precision and background.

  6. Beam diagnostics based on time-domain bunch-by-bunch data

    International Nuclear Information System (INIS)

    A bunch-by-bunch longitudinal feedback system has been used to control coupled-bunch longitudinal motion and study the behavior of the beam at ALS, SPEAR, PEP-II, and DAΦNE. Each of these machines presents unique challenges to feedback control of unstable motion and data analysis. Here we present techniques developed to adapt this feedback system to operating conditions at these accelerators. A diverse array of techniques has been developed to extract information on different aspects of beam behavior from the time-domain data captured by the feedback system. These include measurements of growth and damping rates of coupled-bunch modes, bunch-by-bunch current monitoring, measurements of bunch-by-bunch synchronous phases and longitudinal tunes, and beam noise spectra. A technique is presented which uses the longitudinal feedback system to measure transverse growth and damping rates. Techniques are illustrated with data acquired at all of the four above-mentioned machines

  7. Collective energy loss of attosecond electron bunches

    Energy Technology Data Exchange (ETDEWEB)

    Ogata, A., E-mail: ogata@post.kek.jp [Institute of Scientific and Industrial Research, Osaka University, Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Kondoh, T.; Norizawa, K.; Yang, J.; Yoshida, Y.; Kashiwagi, S. [Institute of Scientific and Industrial Research, Osaka University, Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Kaneko, T. [Department of Applied Physics, Okayama University of Science, Ridai-cho, Kita-ku, Okayama 700-0005 (Japan)

    2011-05-01

    In this study, we have analytically shown that if the electron bunch length is in the 100-as range, the energy loss of the bunch is proportional to the square of the number of electrons in the bunch. If the number of electrons is large, the collective loss introduces a high-energy-density state in the target. The results were verified by carrying out 2D PIC simulations.

  8. Collective energy loss of attosecond electron bunches

    International Nuclear Information System (INIS)

    In this study, we have analytically shown that if the electron bunch length is in the 100-as range, the energy loss of the bunch is proportional to the square of the number of electrons in the bunch. If the number of electrons is large, the collective loss introduces a high-energy-density state in the target. The results were verified by carrying out 2D PIC simulations.

  9. Stabilization of the bunch lengthening in a storage ring

    International Nuclear Information System (INIS)

    The method of increasing the longitudinal focusing is considered as a means against the lengthening effect of an intense bunch in the storage ring. Main limitations of this approach are analyzed. A conclusion for having a big momentum compaction factor to obtain a small longitudinal emittance is made. 5 refs

  10. Bunch Length Measurements in SPEAR3

    Energy Technology Data Exchange (ETDEWEB)

    Corbett, W.J.; Fisher, A.; Huang, X.; Safranek, J.; Sebek, J.; /SLAC; Lumpkin, A.; /Argonne; Sannibale, F.; /LBL, Berkeley; Mok, W.; /Unlisted

    2007-11-28

    A series of bunch length measurements were made in SPEAR3 for two different machine optics. In the achromatic optics the bunch length increases from the low-current value of 16.6ps rms to about 30ps at 25ma/bunch yielding an inductive impedance of -0.17{Omega}. Reducing the momentum compaction factor by a factor of {approx}60 [1] yields a low-current bunch length of {approx}4ps rms. In this paper we review the experimental setup and results.

  11. High power THz source based on coherent radiation of picosecond relativistic electron bunch train

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Tunable and compact high power terahertz (THz) radiation based on coherent radiation (CR) of the picosecond relativistic electron bunch train is under development at the Tsinghua accelerator lab. Coherent synchronization radiation (CSR) and coherent transition radiation (CTR) are researched based on an S-band compact electron linac, a bending magnet or a thin foil. The bunch train’s form factors, which are the key factor of THz radiation, are analyzed by the PARMELA simulation. The effects of electron bunch trains under different conditions, such as the bunch number, bunch charges, micro-pulses inter-distance, and accelerating gradient of the gun are investigated separately in this paper. The optimal radiated THz power and spectra should take these factors as a whole into account.

  12. Enhanced dense attosecond electron bunch generation by irradiating an intense laser on a cone target

    Science.gov (United States)

    Hu, Li-Xiang; Yu, Tong-Pu; Shao, Fu-Qiu; Zou, De-Bin; Yin, Yan

    2015-03-01

    By using two-dimensional particle-in-cell simulations, we demonstrate enhanced spatially periodic attosecond electron bunches generation with an average density of about 10nc and cut-off energy up to 380 MeV. These bunches are acquired from the interaction of an ultra-short ultra-intense laser pulse with a cone target. The laser oscillating field pulls out the cone surface electrons periodically and accelerates them forward via laser pondermotive force. The inner cone wall can effectively guide these bunches and lead to their stable propagation in the cone, resulting in overdense energetic attosecond electron generation. We also consider the influence of laser and cone target parameters on the bunch properties. It indicates that the attosecond electron bunch acceleration and propagation could be significantly enhanced without evident divergency by attaching a plasma capillary to the original cone tip.

  13. Enhanced dense attosecond electron bunch generation by irradiating an intense laser on a cone target

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Li-Xiang; Yu, Tong-Pu, E-mail: tongpu@nudt.edu.cn; Shao, Fu-Qiu; Zou, De-Bin; Yin, Yan [College of Science, National University of Defense Technology, Changsha 410073 (China)

    2015-03-15

    By using two-dimensional particle-in-cell simulations, we demonstrate enhanced spatially periodic attosecond electron bunches generation with an average density of about 10n{sub c} and cut-off energy up to 380 MeV. These bunches are acquired from the interaction of an ultra-short ultra-intense laser pulse with a cone target. The laser oscillating field pulls out the cone surface electrons periodically and accelerates them forward via laser pondermotive force. The inner cone wall can effectively guide these bunches and lead to their stable propagation in the cone, resulting in overdense energetic attosecond electron generation. We also consider the influence of laser and cone target parameters on the bunch properties. It indicates that the attosecond electron bunch acceleration and propagation could be significantly enhanced without evident divergency by attaching a plasma capillary to the original cone tip.

  14. Single bunch beam breakup in linacs and BNS damping

    International Nuclear Information System (INIS)

    We study a single-bunch beam breakup (BBU) problem by a macro-particle model. We consider both the BBU solution and the Landau damping solution which includes the Balakin-Novokhatsky-Smirnov (BNS) damping. In the BBU solution, we get an analytic solution which includes both the Chao-Richter-Yao solution and the two-particle model solution and which agrees well with simulation. The solution can also be used in a multi-bunch case. In the Landau damping solution, we can be see the mechanism of Landau damping formally and can get some insights into BNS damping. We confirm that a two-particle model criterion for BNS damping is a good one. We expect that the two-particle model criterion is represented by the first order interaction in Landau damping solution of a macro-particle model. (author)

  15. Effect of electron beam irradiation and poly(vinylpyrrolidone addition on mechanical properties of polycaprolactone with empty fruit bunch fibre (OPEFB composite

    Directory of Open Access Journals (Sweden)

    2009-04-01

    Full Text Available Biodegradable composites or green composites were prepared by melt blending technique using polycaprolactone and oil palm empty fruit bunch fibre (OPEFB. Since OPEFB is not compatible with PCL a binder, poly(vinyl pyrrolidone, (PVP was used to improve the interaction between PCL and OPEFB. The composites produced were irradiated using electron beam to improve the mechanical properties. The tensile, flexural and impact strengths of PCL/OPEFB composites were improved by addition of 1% by weight of PVP and irradiated with 10 kGy of electron beam. The FTIR spectra indicate a slight increase of frequencies at C=O peaks from 1730 to 1732 cm–1 after irradiation indicates some interaction between C=O and O–H. The surface morphology of the facture surface obtained from tensile test shows no fibre pull out indicating good adhesion between the OPEFB and PCL after addition of PVP.

  16. The effect of temperature on the nutritional quality of feed from biological treated oil palm empty fruit bunch by Pleurotus sajor caju

    International Nuclear Information System (INIS)

    In solid state fermentation, Pleurotus sajor caju degrades oil palm Empty Fruit Bunch (EFB) fibre to give a useful feed material (1). Its chemical composition, dry matter digestibility both in vitro and in vivo have been characterised and described previously (2). However, the performance of this microorganism in degradation activity has not been described. Since CO sub 2 is the most important metabolic product of this fermentation, the microbial degradation activity is directly related to the rate and total CO sub 2 evolved in the fermentation. In this work a range of temperature were selected for fermentation, aiming to suit its practical application for countries of tropical climate in general, particularly Malaysia. The nutritional quality of fermented products obtained from the fermentation at different temperature were analysed and discussed

  17. Effect of adding palm oil mill decanter cake slurry with regular turning operation on the composting process and quality of compost from oil palm empty fruit bunches.

    Science.gov (United States)

    Yahya, Azmi; Sye, Chong Puay; Ishola, Tajudeen Abiodun; Suryanto, Hadi

    2010-11-01

    Formation of compost from oil palm empty fruit bunches (EFB) and decanter cake slurry by adding palm oil mill effluent (POME) with regular turning operation was investigated. The experiment was conducted in a commercial composting plant under the normal production process. The addition of decanter cake slurry has hastened the composting process of the EFB. The C/N ratio after 51 days for the mature compost with the decanter cake slurry was 18.65 while that of the matured compost without the decanter cake slurry remained high at 28.96. The compost formed from the addition of decanter cake to EFB and POME had 46.4% nitrogen, 17.9% phosphorus, 17.7% potassium and 23.1% calcium more than that without decanter cake. The use of compost produced from EFB, POME and decanter cake slurry could solve more environmental problems and enhance economic benefits in the oil palm industry. PMID:20609579

  18. Transverse modes for flat inter-bunch wakes

    CERN Document Server

    Burov, Alexey

    2013-01-01

    If inter-bunch wake fields are flat, i.e. their variations over a bunch length can be neglected, all coherent modes have the same coupled-bunch structure, provided the bunches can be treated as identical by their inner qualities (train theorem). If a flat feedback is strong enough, the transverse modes are single-bunch, provided the inter-bunch wakes are also flat (damper theorem).

  19. TRANSVERSE MODES FOR FLAT INTER-BUNCH WAKES*

    CERN Document Server

    Burov, A

    2013-01-01

    If inter-bunch wake fields are flat, i.e. their variations over a bunch length can be neglected, all coherent modes have the same coupled-bunch structure, provided the bunches can be treated as identical by their inner qualities (train theorem). If a flat feedback is strong enough, the transverse modes are single-bunch, provided the inter-bunch wakes are also flat (damper theorem).

  20. Tolerances of TTF-2 First Bunch Compressor

    International Nuclear Information System (INIS)

    In bunch compressors for SASE-FEL facilities, the projected transverse emittance can be diluted by magnetic multipole component errors in dipoles and dipole misalignments as well as by coherent synchrotron radiation (CSR). In this paper, we describe the multipole field tolerances and the misalignment tolerances of the first bunch compressor (BC2) for the TESLA Test Facility Phase-2 (TTF-2)

  1. Bunch length measurements using synchrotron ligth monitor

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Mahmoud [Old Dominion University, Norfolk, VA; Tiefenback, Michael G. [Jefferson Lab, Newport News, VA

    2015-09-01

    The bunch length is measured at CEBAF using an invasive technique. The technique depends on applying an energy chirp for the electron bunch and imaging it through a dispersive region. The measurements are taken through Arc1 and Arc2 at CEBAF. The fundamental equations, procedure and the latest results are given.

  2. Bucket shaking stops bunch dancing in Tevatron

    CERN Document Server

    Burov, A

    2012-01-01

    Bunches in Tevatron are known to be longitudinally unstable: their collective oscillations, also called "dancing bunches," persist without any signs of decay. Typically, a damper is used to stop these oscillations, but recently, it was theoretically predicted that the oscillations can be stabilized by means of small bucket shaking. Dedicated measurements in Tevatron have shown that this method does stop the dancing.

  3. Ballistic bunching theory of electron cyclotron resonance masers

    Energy Technology Data Exchange (ETDEWEB)

    Baik, C. W.; Jeon, S. G.; Park, G. S. [Seoul National University, Seoul (Korea, Republic of)

    2003-12-15

    A bunching parameter which determines the strength of modulation in electron cyclotron resonance masers (ECRM) is derived using a ballistic bunching theory. Unlike klystrons that utilize space bunching, this bunching parameter strongly depends on the beam velocity ratio due to phase bunching in ECRM. The dependencies of the beam velocity ratio ({approx} {alpha}{sup 2}), the interaction length ({approx} d), and the input drive power ({approx} P{sub in}{sup 1/2}) on the bunching parameter are derived. The orbital phase bunching results calculated using the ballistic bunching theory and a large-signal code are compared and show reasonable agreement.

  4. Longitudinal bunch profile measurements with striplines

    International Nuclear Information System (INIS)

    The use of long constant coupling striplines are proposed to measure the bunch length and even the current profile of the bunch. A measurement of the current profile can be obtained if care is taken in matching the impedance over the stripline or the impulse response is measured. A sampling scope can easily provide the bandwidth necessary for the measurement, but requires the bunch shape to be repetitive. Recent improvements in transient digitizers have made these measurements possible for accelerator operations. Measurements of bunch lengths down to 50 ps are presented. Improvements to striplines and measurement systems are discussed, that could lead to bunch length resolutions of about 10 ps. (R.P.) 8 refs.; 4 figs

  5. Feedback control of coupled-bunch instabilities

    International Nuclear Information System (INIS)

    The next generation of synchrotron light sources and particle accelerators will require active feedback systems to control multi-bunch instabilities. Stabilizing hundreds or thousands of potentially unstable modes in these accelerator designs presents many technical challenges. Feedback systems to stabilize coupled-bunch instabilities may be understood in the frequency domain (mode-based feedback) or in the time domain (bunch-by-bunch feedback). In both approaches an external amplifier system is used to create damping fields that prevent coupled-bunch oscillations from growing without bound. The system requirements for transverse (betatron) and longitudinal (synchrotron) feedback are presented, and possible implementation options developed. Feedback system designs based on digital signal-processing techniques are described. Experimental results are shown from a synchrotron oscillation damper in the SSRL/SLAC storage ring SPEAR that uses digital signal-processing techniques

  6. String formulation of space charge forces in a deflecting bunch

    Science.gov (United States)

    Talman, Richard

    2004-10-01

    The force between two moving point charges, because of its inverse square law singularity, cannot be applied directly in the numerical simulation of bunch dynamics; radiative effects make this especially true for short bunches being deflected by magnets. This paper describes a formalism circumventing this restriction in which the basic ingredient is the total force on a point charge comoving with a longitudinally aligned, uniformly charged string. Bunch evolution can then be treated using direct particle-to-particle, intrabeam scattering, with no need for an intermediate, particle-in-cell, step. Electric and magnetic fields do not appear individually in the theory. Since the basic formulas are both exact (in paraxial approximation) and fully relativistic, they are applicable to beams of all particle types and all energies. But the theory is expected to be especially useful for calculating the emittance growth of the ultrashort electron bunches of current interest for energy recovery linacs and free-electron lasers. The theory subsumes coherent synchrotron radiation and centrifugal space charge force. Renormalized, on-axis, longitudinal field components are in excellent agreement with values from Saldin et al. [DESY Report No. DESY-TESLA-FEL-96-14, 1995; Nucl. Instrum. Methods Phys. Res., Sect. ANIMAER0168-9002 417, 158 (1998).10.1016/S0168-9002(98)00623-8

  7. Analytical bunch compression studies for a linac-based electron accelerator

    Science.gov (United States)

    Schreck, M.; Wesolowski, P.

    2015-10-01

    The current paper deals with analytical bunch compression studies for FLUTE whose results are compared to simulations. FLUTE is a linac-based electron accelerator with a design energy of approximately 40 MeV currently being constructed at the Karlsruhe Institute of Technology. One of the goals of FLUTE is to generate electron bunches with their length lying in the femtosecond regime. In the first phase this will be accomplished using a magnetic bunch compressor. This compressor forms the subject of the studies presented. The paper is divided into two parts. The first part deals with pure geometric investigations of the bunch compressor where space charge effects and the backreaction of bunches with coherent synchrotron radiation are neglected. The second part is dedicated to the treatment of space charge effects. The upshot is that the analytical results in the two parts agree quite well with what is obtained from simulations. This paper shall form the basis for future analytical studies of the FLUTE bunch compressor and of bunch compression, in general.

  8. Growth of Quantum Wires on Step-Bunched Substrate

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Feng

    2005-02-01

    This proposal initiates a combined theoretical and experimental multidisciplinary research effort to explore a novel approach for growing metallic and magnetic nanowires on step-bunched semiconductor and dielectric substrates, and to lay the groundwork for understanding the growth mechanisms and the electronic, electrical, and magnetic properties of metallic and magnetic nanowires. The research will focus on four topics: (1) fundamental studies of step bunching and self-organization in a strained thin film for creating step-bunched substrates. (2) Interaction between metal adatoms (Al,Cu, and Ni) and semiconductor (Si and SiGe) and dielectric (CaF2) surface steps. (3) growth and characterization of metallic and magnetic nanowires on step-bunched templates. (4) fabrication of superlattices of nanowires by growing multilayer films. We propose to attack these problems at both a microscopic and macroscopic level, using state-of-the-art theoretical and experimental techniques. Multiscale (electronic-atomic-continuum) theories will be applied to investigate growth mechanisms of nanowires: mesoscopic modeling and simulation of step flow growth of strained thin films, in particular, step bunching and self-organization will be carried out within the framework of continuum linear elastic theory; atomistic calculation of interaction between metal adatoms and semiconductor and dielectric surface steps will be done by large-scale computations using first-principles total-energy methods. In parallel, thin films and nanowires will be grown by molecular beam epitaxy (MBE), and the resultant structure and morphology will be characterized at the atomic level up to micrometer range, using a combination of different surface/interface probes, including scanning tunneling microscopy (STM, atomic resolution), atomic force microscopy (AFM, nanometer resolution), low-energy electron microscopy (LEEM, micrometer resolution), reflectance high-energy electron diffraction (RHEED), and x

  9. 磷钾素处理对红葱生长和品质的影响%Effects of Phosphorus and Potassium Nutrient on Bunching Onion Growth and Quality

    Institute of Scientific and Technical Information of China (English)

    郑晓宇; 刘厚诚; 宋世威; 孙光闻; 陈日远

    2012-01-01

    以1/2 Hoagland完全营养液配方为基本配方,研究了不同磷钾水平对红葱生长和品质的影响.结果表明:在相同磷浓度下,随着钾浓度升高,红葱单丛质量、单丛叶片数逐渐增加,单丛分蘖数、株高、假茎长和假茎粗有增大趋势;食用部分可溶性糖含量逐渐升高,叶片丙酮酸和大蒜素含量降低.磷浓度为0.25 mmol·L-1时,随着钾浓度升高,红葱食用部分VC含量逐渐增加,硝酸盐含量和可溶性蛋白含量均先增加后降低.P0125K15处理红葱叶片和假茎总酚及总黄酮含量最高.%Effects of phosphorus and potassium on the growth and qualities in bunching onion ( Allium fistulosum L. var. caespitosum Makino ) were studied with hydroponics, in which the solution is 1/2 Hoagland's, and treatments were P0.125K0.75, P0.125K1.5, P0.125K3, P0.25K0.75, P0.25K1.5 ( CK ), P0.25K3, and the potassium levels were Kl 0.75 mmol · L-1 K2 1.5 mmol o L-1, K3 3 mmol o L-1 PI 0.125 mmol o L-1 P2 0.25 mmol o L-1. The results showed that at the same phosphorus level, with the potassium concentration increased, the yield and leaf number of bunching onion gradually increased and the tiller numbers, plant height, length and diameter of cauloid were in increasing trend. The contents of soluble sugar in edible part also gradually increased, while the contents of allicin and pyruvic acid in leaf decreased. At 0.25 mmol o L-1 phosphorus level, with the concentration of potassium increased, the contents of VC in edible part of bunching onion gradually increased, but the contents of nitrate and soluble protein increased first then decreased. The contents of total phenolics and flavone in leaf and stem were the highest when treated with P0.125K1.5.

  10. Shielded transient self-interaction of a bunch entering a circle from a straight path

    International Nuclear Information System (INIS)

    When a short (mm-length) bunch with high (nC-regime) charge is transported through a magnetic bending system, self-interaction via coherent synchrotron radiation (CSR) and space charge may alter the bunch dynamics significantly. The authors consider a Gaussian rigid-line-charge bunch following a straight-path trajectory into a circle, with the trajectory centered between two infinite, parallel, perfectly conducting plates. Transients associated with CSR and space charge generated from source particles both on the straight path and the circle are calculated, and their net effect on the radiated power is contrasted with that of shielded steady-state CSR

  11. Distortion of Crabbed Bunch Due to Electron Cloud and Global Crabbing

    International Nuclear Information System (INIS)

    Crab cavities may be used improve the luminosity in colliding beam colliders with crab crossing. In a global crab crossing correction, only one crab cavity is installed in each ring and the crab cavities generate a horizontally titled bunch oscillating around the ring. The electron cloud in positively charged rings may distort the crabbed bunch and cause the luminosity drop. This paper briefly estimates the distortion of positron bunch due to the electron cloud with global crab and estimates the effect in the KEKB and possible LHC upgrades

  12. Transverse modes and instabilities of a bunched beam with space charge and resistive wall impedance

    Energy Technology Data Exchange (ETDEWEB)

    Balbekov, V.; /Fermilab

    2011-11-01

    Transverse instability of a bunch in a ring accelerator is considered with space charge and wakefield taken into account. It is assumed that space charge tune shift significantly exceeds the synchrotron tune. Bunch spectrum, instability growth rate, and effects of chromaticity are studied with different bunch and wake forms. Fast instability caused by coupling of transverse modes is studied in detail. It is shown that, for monotonic wakes, the transverse mode coupling instability is possible only with a certain sign of the wake. Its threshold and growth rate are calculated precisely over a wide range of parameters.

  13. Study of CSR longitudinal bunch compression cavity

    International Nuclear Information System (INIS)

    The scheme of longitudinal bunch compression cavity for the Cooling Storage Ring (CSR)is an important issue. Plasma physics experiments require high density heavy ion beam and short pulsed bunch,which can be produced by non-adiabatic compression of bunch implemented by a fast compression with 90 degree rotation in the longitudinal phase space. The phase space rotation in fast compression is initiated by a fast jump of the RF-voltage amplitude. For this purpose, the CSR longitudinal bunch compression cavity, loaded with FINEMET-FT-1M is studied and simulated with MAFIA code. In this paper, the CSR longitudinal bunch compression cavity is simulated and the initial bunch length of 238U72+ with 250 MeV/u will be compressed from 200 ns to 50 ns.The construction and RF properties of the CSR longitudinal bunch compression cavity are simulated and calculated also with MAFIA code. The operation frequency of the cavity is 1.15 MHz with peak voltage of 80 kV, and the cavity can be used to compress heavy ions in the CSR. (authors)

  14. Bunching system of the KEKB linac

    International Nuclear Information System (INIS)

    At present, the KEK 2.5-GeV Linac is being upgraded as the injector of the KEK B-factory (KEKB). One of the most important changes is to increase the intensities of positron beams injected into a KEKB ring; it is, therefore, required to accelerate high-intensity single-bunch electron beams to high energy, 3.7 GeV, where they are converted to positron beams. For the purpose, the primary electron bunch should have more than 10 nC. Furthermore, the bunch lengths must be limited as short as 10 ps, in order to achieve narrow energy spreads of primary electron beams, and produce positron beams of short bunch lengths, as well. The bunching system has been designed to meet these requirements, introducing subharmonic bunchers (SHB). This paper describes the upgrade of the bunching system and the results of simulations of bunching using PARMELA. The designs and RF test of SHB cavities are described. (author)

  15. Multi-mode, multi-bunch dielectric wake field resonator accelerator

    International Nuclear Information System (INIS)

    We describe a multi-mode, dielectric-lined cylindrical resonator equipped with end reflectors in which wake fields are built up by a sequence of compact drive bunches. The parameters of the resonator are chosen such that the period of the wake fields is the same as the spacing of the drive bunches, and the length of the resonator is taken to be a half-integer multiple of the wake field period. Thus the wake field of a passing charge bunch will travel down the resonator and back so as to arrive at the front reflector just as the next bunch enters. Wake fields remain well defined because, excepting the lowest frequency TM mode, the resonator length is very nearly an integer multiple of the individual mode half-wavelengths. The device thus resembles a mode-locked laser resonator equipped with an 'optical switch' (the passing bunches here). By numerical simulation, we find that the wake field amplitudes will increase with additional bunches, and show an example for an experiment to be done at the Yale Beam Physics Laboratory. For the first time we show how wake fields are reflected from boundary surfaces, an effect that should occur in every dielectric wake field apparatus and which we now exploit to advantage. The resonator concept permits a staged accelerator system, and could reduce the severity of beam bunch breakup due to charge asymmetries

  16. Capture, acceleration and bunching rf systems for the MEIC booster and storage rings

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shaoheng [Jefferson Lab, Newport News, VA; Guo, Jiquan [Jefferson Lab, Newport News, VA; Lin, Fanglei [Jefferson Lab, Newport News, VA; Morozov, Vasiliy [Jefferson Lab, Newport News, VA; Rimmer, Robert A. [Jefferson Lab, Newport News, VA; Wang, Haipeng [Jefferson Lab, Newport News, VA; Zhang, Yuhong [Jefferson Lab, Newport News, VA

    2015-09-01

    The Medium-energy Electron Ion Collider (MEIC), proposed by Jefferson Lab, consists of a series of accelerators. The electron collider ring accepts electrons from CEBAF at energies from 3 to 12 GeV. Protons and ions are delivered to a booster and captured in a long bunch before being ramped and transferred to the ion collider ring. The ion collider ring accelerates a small number of long ion bunches to colliding energy before they are re-bunched into a high frequency train of very short bunches for colliding. Two sets of low frequency RF systems are needed for the long ion bunch energy ramping in the booster and ion collider ring. Another two sets of high frequency RF cavities are needed for re-bunching in the ion collider ring and compensating synchrotron radiation energy loss in the electron collider ring. The requirements from energy ramping, ion beam bunching, electron beam energy compensation, collective effects, beam loading and feedback capability, RF power capability, etc. are presented. The preliminary designs of these RF systems are presented. Concepts for the baseline cavity and RF station configurations are described, as well as some options that may allow more flexible injection and acceleration schemes.

  17. Van Kampen modes for bunch longitudinal motion

    Energy Technology Data Exchange (ETDEWEB)

    Burov, A.; /Fermilab

    2010-09-01

    Conditions for existence, uniqueness and stability of bunch steady states are considered. For the existence uniqueness problem, simple algebraic equations are derived, showing the result both for the action and Hamiltonian domain distributions. For the stability problem, van Kampen theory is used. Emerging of discrete van Kampen modes show either loss of Landau damping, or instability. This method can be applied for an arbitrary impedance, RF shape and beam distribution function Available areas on intensity-emittance plane are shown for resistive wall wake and single harmonic, bunch shortening and bunch lengthening RF configurations. Language of van Kampen modes is a powerful tool for studying beam stability. Its unique efficiency reveals itself in those complicated cases, when the dielectric function cannot be obtained, as it is for the longitudinal bunch motion. Emergence of a discrete mode means either loss of Landau damping or instability. By definition, the discrete modes lie outside the continuous incoherent spectrum, but they still may stay within the bucket. In the last case, the discrete mode would disappear after a tiny portion of resonant particles would be added. However, if the discrete mode lie outside the bucket, the Landau damping cannot be restored by tiny perturbation of the particle distribution; LLD is called radical in that case. For a given bunch emittance and RF voltage, the intensity is limited either by reduction of the bucket acceptance or by (radical) LLD. In this paper, results are presented for longitudinal bunch stability in weak head-tail approximation and resistive wall impedance; three RF configurations are studied: single harmonic, bunch shortening and bunch lengthening. It is shown that every RF configuration may be preferable, depending on the bunch emittance and intensity.

  18. Coupled-bunch instabilities in RHIC

    International Nuclear Information System (INIS)

    We used the program ZAP to evaluate the coupled-bunch modes for the case of 57 equally spaced bunches with the Sacherer-Zotter formalism assuming parabolic bunches. The sources of coupling impedances assumed were space charge, resistive wall, broadband, and rf cavity fundamental and parasitic modes. Generally the studies assumed a stainless steel vacuum chamber, but we did perform a comparison run using a stainless steel chamber internally coated with a thin cold copper layer. These latter investigations were motivated by the proposal for coating which would reduce parasitic wall heating in the vacuum chambers in the superconducting dipoles. 10 tabs

  19. Plasma-driven ultrashort bunch diagnostics

    Science.gov (United States)

    Dornmair, I.; Schroeder, C. B.; Floettmann, K.; Marchetti, B.; Maier, A. R.

    2016-06-01

    Ultrashort electron bunches are crucial for an increasing number of applications, however, diagnosing their longitudinal phase space remains a challenge. We propose a new method that harnesses the strong electric fields present in a laser driven plasma wakefield. By transversely displacing driver laser and witness bunch, a streaking field is applied to the bunch. This field maps the time information to a transverse momentum change and, consequently, to a change of transverse position. We illustrate our method with simulations where we achieve a time resolution in the attosecond range.

  20. Plasma-driven ultrashort bunch diagnostic

    CERN Document Server

    Dornmair, I; Floettmann, K; Marchetti, B; Maier, A R

    2016-01-01

    Ultrashort electron bunches are crucial for an increasing number of applications, however, diagnosing their longitudinal phase space remains a challenge. We propose a new method that harnesses the strong electric fields present in a laser driven plasma wakefield. By transversely displacing driver laser and witness bunch, a streaking field is applied to the bunch. This field maps the time information to a transverse momentum change and, consequently, to a change of transverse position. We illustrate our method with simulations where we achieve a time resolution in the attosecond range.

  1. Van Kampen modes for bunch longitudinal motion

    CERN Document Server

    Burov, A

    2012-01-01

    Conditions for existence, uniqueness and stability of bunch steady states are considered. For the existence uniqueness problem, simple algebraic equations are derived, showing the result both for the action and Hamiltonian domain distributions. For the stability problem, van Kampen theory is used. Emerging of discrete van Kampen modes show either loss of Landau damping, or instability. This method can be applied for an arbitrary impedance, RF shape and beam distribution function Available areas on intensity-emittance plane are shown for resistive wall wake and single harmonic, bunch shortening and bunch lengthening RF configurations.

  2. A sensitive beam-bunch phase detector

    International Nuclear Information System (INIS)

    A sensitive heavy-ion beam-bunch phase detector has been developed by first examining the relationship between the sensitivity of an rf resonant cavity as a particle bunch detector and the shunt impedance of the same cavity as an accelerating structure. Then the various high shunt impedance rf cavities previously developed for accelerating heavy ions were evaluated for use as bunch detectors. A spiral-loaded geometry was chosen, built, and tested with beam. The sensitivity obtained, 14 μ V per electrical nA of beam, is a factor 3 higher than previously reported. (orig.)

  3. Effect of carbonization temperature on the physical and electrochemical properties of supercapacitor electrode from fibers of oil palm empty fruit bunches

    Energy Technology Data Exchange (ETDEWEB)

    Ishak, M. M.; Deraman, M., E-mail: madra@ukm.my; Talib, I. A.; Basri, N. H.; Omar, R.; Nor, N. S. M.; Dolah, B. N. M. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Awitdrus,; Farma, R.; Taer, E. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia); Department of Physics, Faculty of Mathematics and Natural Sciences, University of Riau, 28293 Pekanbaru, Riau (Indonesia)

    2015-04-16

    Self-adhesive carbon grains (SACG) was prepared from fibers of oil palm empty fruit bunches. The SACG green monoliths were carbonized in N{sub 2} environment at 400, 500, 600 and 700°C to produce carbon monoliths labeled as CM1, CM2, CM3 and CM4 respectively. The CMs were activated in CO{sub 2} surrounding at 800°C for 1 hour to produce activated carbon monolith electrodes (ACM1, ACM2, ACM3 and ACM4). The physical properties of the CMs and ACMs were investigated using X-ray diffraction, field emission scanning electron microscopy (FESEM) and N{sub 2} adsorption-desorption isotherm techniques. ACMs were used as electrode to fabricate symmetry supercapacitor cells and the cells’ performances were investigated using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) standard techniques. In this paper we report the physical and electrochemical properties of the ACM electrodes by analyzing the influence of the carbonization temperature on these properties.

  4. Effects of changes in chemical and structural characteristic of ammonia fibre expansion (AFEX) pretreated oil palm empty fruit bunch fibre on enzymatic saccharification and fermentability for biohydrogen.

    Science.gov (United States)

    Abdul, Peer Mohamed; Jahim, Jamaliah Md; Harun, Shuhaida; Markom, Masturah; Lutpi, Nabilah Aminah; Hassan, Osman; Balan, Venkatesh; Dale, Bruce E; Mohd Nor, Mohd Tusirin

    2016-07-01

    Oil palm empty fruit bunch (OPEFB) fibre is widely available in Southeast Asian countries and found to have 60% (w/w) sugar components. OPEFB was pretreated using the ammonia fibre expansion (AFEX) method and characterised physically by the Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The results show that there were significant structural changes in OPEFB after the pretreatment step, and the sugar yield after enzymatic hydrolysis using a cocktail of Cellic Ctec2® and Cellic Htec2® increased from 0.15gg(-1) of OPEFB in the raw untreated OPEFB sample to 0.53gg(-1) of OPEFB in AFEX-pretreated OPEFB (i.e. almost a fourfold increase in sugar conversion), which enhances the economic value of OPEFB. A biohydrogen fermentability test of this hydrolysate was carried out using a locally isolated bacterium, Enterobacter sp. KBH6958. The biohydrogen yield after 72h of fermentation was 1.68mol H2 per mol sugar. Butyrate, ethanol, and acetate were the major metabolites. PMID:27017130

  5. Effect of carbonization temperature on the physical and electrochemical properties of supercapacitor electrode from fibers of oil palm empty fruit bunches

    Science.gov (United States)

    Ishak, M. M.; Deraman, M.; Talib, I. A.; Basri, N. H.; Awitdrus, Farma, R.; Taer, E.; Omar, R.; Nor, N. S. M.; Dolah, B. N. M.

    2015-04-01

    Self-adhesive carbon grains (SACG) was prepared from fibers of oil palm empty fruit bunches. The SACG green monoliths were carbonized in N2 environment at 400, 500, 600 and 700°C to produce carbon monoliths labeled as CM1, CM2, CM3 and CM4 respectively. The CMs were activated in CO2 surrounding at 800°C for 1 hour to produce activated carbon monolith electrodes (ACM1, ACM2, ACM3 and ACM4). The physical properties of the CMs and ACMs were investigated using X-ray diffraction, field emission scanning electron microscopy (FESEM) and N2 adsorption-desorption isotherm techniques. ACMs were used as electrode to fabricate symmetry supercapacitor cells and the cells' performances were investigated using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) standard techniques. In this paper we report the physical and electrochemical properties of the ACM electrodes by analyzing the influence of the carbonization temperature on these properties.

  6. Effect of reduction roasting by using bio-char derived from empty fruit bunch on the magnetic properties of Malaysian iron ore

    Institute of Scientific and Technical Information of China (English)

    Nurul A. Yunus; Mohd H. Ani; Hamzah M. Salleh; Rusila Z. A. Rashid; Tomohiro Akiyama; Hadi Purwanto; Nur E. F. Othman

    2014-01-01

    Beneficiation of Malaysian iron ore is becoming necessary as iron resources are depleting. However, the upgrading process is challenging because of the weak magnetic properties of Malaysian iron ore. In this study, bio-char derived from oil palm empty fruit bunch (EFB) was utilized as an energy source for reduction roasting. Mixtures of Malaysian iron ore and the bio-char were pressed into briquettes and subjected to reduction roasting processes at 873-1173 K. The extent of reduction was estimated on the basis of mass loss, and the mag-netization of samples was measured using a vibrating sample magnetometer (VSM). When reduced at 873 K, the original goethite-rich ore was converted into hematite. An increase in temperature to 1073 K caused a significant conversion of hematite into magnetite and enhanced the magnetic susceptibility and saturation magnetization of samples. The magnetic properties diminished at 1173 K as the iron ore was par-tially reduced to wustite. This reduction roasting by using the bio-char can assist in upgrading the iron ore by improving its magnetic proper-ties.

  7. Effect of carbonization temperature on the physical and electrochemical properties of supercapacitor electrode from fibers of oil palm empty fruit bunches

    International Nuclear Information System (INIS)

    Self-adhesive carbon grains (SACG) was prepared from fibers of oil palm empty fruit bunches. The SACG green monoliths were carbonized in N2 environment at 400, 500, 600 and 700°C to produce carbon monoliths labeled as CM1, CM2, CM3 and CM4 respectively. The CMs were activated in CO2 surrounding at 800°C for 1 hour to produce activated carbon monolith electrodes (ACM1, ACM2, ACM3 and ACM4). The physical properties of the CMs and ACMs were investigated using X-ray diffraction, field emission scanning electron microscopy (FESEM) and N2 adsorption-desorption isotherm techniques. ACMs were used as electrode to fabricate symmetry supercapacitor cells and the cells’ performances were investigated using electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) standard techniques. In this paper we report the physical and electrochemical properties of the ACM electrodes by analyzing the influence of the carbonization temperature on these properties

  8. Effect of reduction roasting by using bio-char derived from empty fruit bunch on the magnetic properties of Malaysian iron ore

    Science.gov (United States)

    Yunus, Nurul A.; Ani, Mohd H.; Salleh, Hamzah M.; Rashid, Rusila Z. A.; Akiyama, Tomohiro; Purwanto, Hadi; Othman, Nur E. F.

    2014-04-01

    Beneficiation of Malaysian iron ore is becoming necessary as iron resources are depleting. However, the upgrading process is challenging because of the weak magnetic properties of Malaysian iron ore. In this study, bio-char derived from oil palm empty fruit bunch (EFB) was utilized as an energy source for reduction roasting. Mixtures of Malaysian iron ore and the bio-char were pressed into briquettes and subjected to reduction roasting processes at 873-1173 K. The extent of reduction was estimated on the basis of mass loss, and the magnetization of samples was measured using a vibrating sample magnetometer (VSM). When reduced at 873 K, the original goethite-rich ore was converted into hematite. An increase in temperature to 1073 K caused a significant conversion of hematite into magnetite and enhanced the magnetic susceptibility and saturation magnetization of samples. The magnetic properties diminished at 1173 K as the iron ore was partially reduced to wustite. This reduction roasting by using the bio-char can assist in upgrading the iron ore by improving its magnetic properties.

  9. Thermal Stability of Oil Palm Empty Fruit Bunch (OPEFB) Nanocrystalline Cellulose: Effects of post-treatment of oven drying and solvent exchange techniques

    Science.gov (United States)

    Indarti, E.; Marwan; Wanrosli, W. D.

    2015-06-01

    Nanocrystallinecellulose (NCC) from biomass is a promising material with huge potentials in various applications. A big challenge in its utilization is the agglomeration of the NCC's during processing due to hydrogen bonding among the cellulose chains when in close proximity to each other. Obtaining NCC's in a non-agglomerated and non-aqueous condition is challenging. In the present work NCC's was isolated from oil palm empty fruit bunch (OPEFB) using TEMPO-oxidation reaction method. To obtain non-agglomerated and non-aqueous products, the NCC's underwent post-treatment using oven drying (OD) and solvent exchanged (SE) techniques. The thermal stability of all samples was determined from TGA and DTG profiles whilst FTIR was used to analyzethe chemical modifications that occurred under these conditions. NCC-SE has better thermal stability than the NCC-OD and its on-set degradation temperature and residue are also higher. FTIR analysis shows that NCC-SE has a slightly different chemical composition whereby the absorption band at 1300 cm-1 (due to C-O symmetric stretching) is absent as compared to NCC-OD indicating that in NCC-SE the carboxylate group is in acid form which contribute to its thermal stability

  10. Laser acceleration of ion bunches at the front surface of overdense plasmas

    OpenAIRE

    Macchi, Andrea; Cattani, Federica; Liseykina, Tatiana V.; Cornolti, Fulvio

    2004-01-01

    The acceleration of ions in the interaction of high intensity laser pulses with overdense plasmas is investigated with particle-in-cell simulations. For circular polarization of the laser pulses, high-density ion bunches moving into the plasma are generated at the laser-plasma interaction surface. A simple analytical model accounts for the numerical observations and provides scaling laws for the ion bunch energy and generation time as a function of pulse intensity and plasma density.

  11. Multiple frequency generation by bunched solitons in Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Lomdahl, P. S.; Sørensen, O. H.; Christiansen, Peter Leth; Scott, A. C.; Eilbeck, J. C.

    1981-01-01

    A detailed numerical study of a long Josephson tunnel junction modeled by a perturbed sine-Gordon equation demonstrates the existence of a variety of bunched soliton configurations. Thus, on the third zero-field step of the V-I characteristic, two simultaneous adjacent frequencies are generated in...... a narrow bias current range. The analysis of the soliton modes provides an explanation of recent experimental observations....

  12. Bucket Shaking Stops Bunch Oscillations In The Tevatron

    CERN Document Server

    Tan, C Y

    2011-01-01

    Bunches in the Tevatron are known to exhibit longitudinal oscillations which persist indefinitely. These oscillations are colloquially called "dancing bunches". Although the dancing bunches do not cause single bunch emittance growth or beam loss at injection, it leads to bunch lengthening at collisions. In operations, a longitudinal damper has been built which stops this dance and damps out coupled bunch modes. Recent theoretical work predicts that the dance can also be stopped by an appropriate change in the bunch distribution. This paper shows the Tevatron experiments which support this theory.

  13. Properties of Trapped Electron Bunches in a Plasma Wakefield Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Kirby, Neil; /SLAC

    2009-10-30

    Plasma-based accelerators use the propagation of a drive bunch through plasma to create large electric fields. Recent plasma wakefield accelerator (PWFA) experiments, carried out at the Stanford Linear Accelerator Center (SLAC), successfully doubled the energy for some of the 42 GeV drive bunch electrons in less than a meter; this feat would have required 3 km in the SLAC linac. This dissertation covers one phenomenon associated with the PWFA, electron trapping. Recently it was shown that PWFAs, operated in the nonlinear bubble regime, can trap electrons that are released by ionization inside the plasma wake and accelerate them to high energies. These trapped electrons occupy and can degrade the accelerating portion of the plasma wake, so it is important to understand their origins and how to remove them. Here, the onset of electron trapping is connected to the drive bunch properties. Additionally, the trapped electron bunches are observed with normalized transverse emittance divided by peak current, {epsilon}{sub N,x}/I{sub t}, below the level of 0.2 {micro}m/kA. A theoretical model of the trapped electron emittance, developed here, indicates that the emittance scales inversely with the square root of the plasma density in the non-linear 'bubble' regime of the PWFA. This model and simulations indicate that the observed values of {epsilon}{sub N,x}/I{sub t} result from multi-GeV trapped electron bunches with emittances of a few {micro}m and multi-kA peak currents. These properties make the trapped electrons a possible particle source for next generation light sources. This dissertation is organized as follows. The first chapter is an overview of the PWFA, which includes a review of the accelerating and focusing fields and a survey of the remaining issues for a plasma-based particle collider. Then, the second chapter examines the physics of electron trapping in the PWFA. The third chapter uses theory and simulations to analyze the properties of the trapped

  14. Real-time single-shot electron bunch length measurements

    CERN Document Server

    Wilke, I; Gillespie, W A; Berden, G; Knippels, G M H; Meer, A F G

    2002-01-01

    Linear accelerators employed as drivers for X-ray free electron lasers (FELs) require relativistic electron bunch with sub-picosecond bunch length. Precise bunch length measurements are important for the tuning and operation of the FELs. Previously, we have demonstrated that electro-optic detection is a powerful technique for sub-picosecond electron bunch length measurements. In those experiments, the measured bunch length was the average of all electron bunches within a macropulse. Here, for the first time, we present the measurement of the length of individual electron bunches using a development of our previous technique. In this experiment, the longitudinal electron bunch shape is encoded electro-optically on to the frequency spectrum of a chirped laser pulse. Subsequently, the laser pulse is dispersed by a grating and the spectrum is imaged with a CCD camera. Single bunch measurements are achieved by using a nanosecond gated camera, and synchronizing the gate with both the electron bunch and the laser pu...

  15. Bunch-by-bunch longitudinal feedback system for PEP-II

    International Nuclear Information System (INIS)

    This paper describes the implementation of the bunch-by-bunch longitudinal feedback system for the PEP-II B Factory. Bunch spacing down to 2 ns is achieved using 500 Megasamples per second A/D and D/A converters, and AT ampersand T 1610 Digital Signal Processors are integrated to run a downsampled feedback algorithm for each bunch in parallel. This general purpose programmable system, packaged in VXI and VME, is modular and scalable to offer portability to other accelerator rings. The control and monitoring hardware and software architecture have been developed to provide ease of operation as well as diagnostic tools for machine physics

  16. Longitudinal bunch profile measurements with striplines

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, S.L.

    1992-01-01

    Striplines beam position monitors are normally considered low frequency devices with at best an octave bandwidth. Some attempts to make them very high frequency and broadband have led to long and complicated tapered construction. However, conventional uniform coupling striplines can provide very high frequency and broadband response, if the downstream induced signal is gated out electronically. In this case, the leading edge beam signal can provide bunch length and even current profile information for bunch lengths shorter than the length of the stripline. Recent improvement in transient digitizers have made these measurements possible for accelerator operations. Measurements of bunch lengths down to 50 psec are results are presented. Improvements to striplines and measurement systems are discussed, that could lead to bunch length resolutions {approx} 10 psec.

  17. Longitudinal bunch profile measurements with striplines

    Energy Technology Data Exchange (ETDEWEB)

    Kramer, S.L.

    1992-05-01

    Striplines beam position monitors are normally considered low frequency devices with at best an octave bandwidth. Some attempts to make them very high frequency and broadband have led to long and complicated tapered construction. However, conventional uniform coupling striplines can provide very high frequency and broadband response, if the downstream induced signal is gated out electronically. In this case, the leading edge beam signal can provide bunch length and even current profile information for bunch lengths shorter than the length of the stripline. Recent improvement in transient digitizers have made these measurements possible for accelerator operations. Measurements of bunch lengths down to 50 psec are results are presented. Improvements to striplines and measurement systems are discussed, that could lead to bunch length resolutions {approx} 10 psec.

  18. Bunch Shape Monitor for SSCL linac

    International Nuclear Information System (INIS)

    The Superconducting Super Collider Laboratory and the Institute for Nuclear Research ore collaboratively developing a Bunch Shape Monitor diagnostics for commission the SSCL linac. The Bunch Shape Monitor is designed to measure the intensity of beam as a function of time over the micro-bunch of the beam. Design resolution for the SSCL monitors is approximately 7 psec. The first monitor will operate at the fundamental frequency of 428 MHz and will be used to measure the output beam of the RFQ Linac. First available results will be presented and compared with predictions. Further development will allow the monitors to fit in a standard SSCL beam box and one will operate at the third harmonic of 428 MHz. Proposals to use the Bunch Shape Monitor to measure the longitudinal phase space distribution of the beam will be discussed

  19. Bunch shape monitor for SSCL linac

    International Nuclear Information System (INIS)

    The Superconducting Super Collider Laboratory and the Institute for Nuclear Research are collaboratively developing a Bunch Shape Monitor diagnostic for commissioning the SSCL linac. The Bunch Shape Monitor is designed to measure the intensity of beam as a function of time over the micro-bunch of the beam. Design resolution for the SSCL monitors is approximately 7 psec. The first monitor will operate at the fundamental frequency of 428 MHz and will be used to measure and output beam of the RFQ Linac. First available results will be presented and compared with predictions. Further development will allow the monitors to fit in a standard SSCL beam box and one will operate at the third harmonic of 428 MHz. Proposals to use the Bunch Shape Monitor to measure the longitudinal phase space distribution of the beam will be discussed

  20. Bunch compression for the TLC: Preliminary design

    International Nuclear Information System (INIS)

    A preliminary design of a TLC bunch compressor as a two-stage device is described. The main parameters of the compressor, as well as results of some simulations, are presented. They show that the ideal system (no imperfections) does the job of transmitting transverse emittances without distortions (at least up to the second-order terms) producing at the same time the desired bunch length of 50 μm. 9 refs., 6 figs., 4 tabs

  1. Bio-oils from Pyrolysis of Oil Palm Empty Fruit Bunches

    OpenAIRE

    Mohamad A. Sukiran; Chow M. Chin; Nor K.A. Bakar

    2009-01-01

    Problem Statement: The palm oil industry generates an abundance of oil palm biomass such as the mesocarp fibre, shell, empty fruit bunch (EFB), frond, trunk and palm oil mill effluent (POME). For 80 million tonnes of fresh fruit bunch (FFB) processed last year, the amount of oil palm biomass was more than 25 million tones. The objectives of this study were to: (i) Determine the effect of various pyrolysis parameters on product yields and (ii) Characterise liquid product obtained under differe...

  2. Self-modulation instability of a long proton bunch in plasmas

    CERN Document Server

    Kumar, Naveen; Lotov, Konstantin

    2010-01-01

    An analytical model for the self-modulation instability of a long relativistic proton bunch propagating in uniform plasmas is developed. The self-modulated proton bunch resonantly excites a large amplitude plasma wave (wake field), which can be used for acceleration of plasma electrons. Analytical expressions for the linear growth rate and the number of exponentiations are given. We use the full three-dimensional particle-in-cell (PIC) simulations to study the beam self-modulation and the transition to the nonlinear stage. It is shown that the self-modulation of the proton bunch competes with the hosing instability which tends to destroy the plasma wave. A method is proposed and studied through PIC simulations to circumvent this problem which relies on the seeding of the self-modulation instability in the bunch.

  3. Bunch lengthening calculations for the SLC [Stanford Linear Collider] damping rings

    International Nuclear Information System (INIS)

    The problem of bunch lengthening in electron storage rings has been treated by many people, and there have been many experiments. In the typical experiment, the theory is used to determine the impedance of the ring. What has been lacking thus far, however, is a calculation of bunch lengthening that uses a carefully calculated ring impedance (or wakefield). In this paper we begin by finding the potential well distortion due to some very simple impedance models, in order to illustrate different types of bunch lengthening behavior. We then give a prescription for extending potential well calculations into the turbulent regime once the threshold is known. Then finally, using the wakefield calculated for the SLC damping rings, combined with the measured value of the threshold, we calculate bunch lengthening for the damping rings, and compare the results with the measurements. 9 refs., 6 figs

  4. Flat Bunches with a Hollow Distribution for Space Charge Mitigation

    CERN Document Server

    Oeftiger, Adrian; Findlay, Alan James; Hancock, Steven; Rumolo, Giovanni

    2016-01-01

    Longitudinally hollow bunches provide one means to mitigate the impact of transverse space charge. The hollow distributions are created via dipolar parametric excitation during acceleration in CERN's Proton Synchrotron Booster. We present simulation work and beam measurements. Particular emphasis is given to the alleviation of space charge effects on the long injection plateau of the downstream Proton Synchrotron machine, which is the main goal of this study.

  5. Feasibility study of stochastic cooling of bunches in the SPS

    International Nuclear Information System (INIS)

    The average luminosity of the SPS collider could be improved if the slow blow-up of transverse emittances due to beam-beam and intrabeam scattering effects were to be reduced by a transverse cooling system. We examine the parameters of such a system and propose a technological approach which seems better suited to the case of a few bunches circulating in a large machine. (orig./HSI)

  6. Compact noninvasive electron bunch-length monitor

    International Nuclear Information System (INIS)

    A compact RF cavity was constructed that simultaneously resonates at many harmonic modes when excited by a bunched electron beam passing through its bore. The excitation of these modes provides a Fourier description of the temporal characteristics of the bunchtrain. The cavity was used to non-invasively characterize electron bunches produced from thin and thick GaAs photocathodes inside a DC high voltage photogun illuminated with 37 ps (FWHM) laser pulses at repetition rates near 500 and 1500 MHz, at average beam current from 5 uA to 500 uA and at beam energy from 75 keV to 195 keV. The cavity bunchlength monitor could detect electron bunches as short as 57 ps (FWHM) when connected directly to a sampling oscilloscope, and could clearly distinguish bunches with varying degrees of space-charge induced growth and with different tail signatures. Efforts are underway to detect shorter bunches, by designing cavities with increased bandwidth and improved coupling uniformity. This demonstration lends credibility to the idea that these cavities could also be used for other applications, including bunching and shaping, when driven with external RF

  7. Bucket shaking stops bunch dancing in Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Burov, A.; Tan, C.Y.; /Fermilab

    2011-03-01

    Bunches in Tevatron are known to be longitudinally unstable: their collective oscillations, also called dancing bunches, persist without any signs of decay. Typically, a damper is used to stop these oscillations, but recently, it was theoretically predicted that the oscillations can be stabilized by means of small bucket shaking. Dedicated measurements in Tevatron have shown that this method does stop the dancing. According to predictions of Refs. [2,3], the flattening of the bunch distribution at low amplitudes should make the bunch more stable against LLD. An experiment has been devised to flatten the distribution by modulating the RF phase at the low-amplitude synchrotron frequency for a few degrees of amplitude. These beam studies show that stabilisation really happens. After several consecutive shakings, the dancing disappears and the resulting bunch profile becomes smoother at the top. Although not shown in this report, sometimes a little divot forms at the centre of the distribution. These experiments confirm that resonant RF shaking flattens the bunch distribution at low amplitudes, and the dancing stops.

  8. Bucket shaking stops bunch dancing in Tevatron

    International Nuclear Information System (INIS)

    Bunches in Tevatron are known to be longitudinally unstable: their collective oscillations, also called dancing bunches, persist without any signs of decay. Typically, a damper is used to stop these oscillations, but recently, it was theoretically predicted that the oscillations can be stabilized by means of small bucket shaking. Dedicated measurements in Tevatron have shown that this method does stop the dancing. According to predictions of Refs. (2,3), the flattening of the bunch distribution at low amplitudes should make the bunch more stable against LLD. An experiment has been devised to flatten the distribution by modulating the RF phase at the low-amplitude synchrotron frequency for a few degrees of amplitude. These beam studies show that stabilisation really happens. After several consecutive shakings, the dancing disappears and the resulting bunch profile becomes smoother at the top. Although not shown in this report, sometimes a little divot forms at the centre of the distribution. These experiments confirm that resonant RF shaking flattens the bunch distribution at low amplitudes, and the dancing stops.

  9. Generation of attosecond electron bunches

    International Nuclear Information System (INIS)

    Ultra-fast science is an important new research frontier that is driving the development of novel sources for generation of extremely short x-ray and electron pulses. Recent advances in femtosecond lasers have stimulated development of femtosecond x-ray sources that allow the study of matter at the time scale shorter than period of oscillations of atoms in molecules, ∼ 100 fs. The next breakthrough would be a source of electron pulses comparable with atomic periods ω-1 ∼ 100 attosecond (10-16 s), where ω is a transition frequency between atomic levels. This will open qualitatively new class of phenomena based on the interaction of atomic electrons in the medium with a collective electric field of electron pulses and not with their individual electrons. For example, one can expect coherent ionization losses that are proportional to a square number of electrons in the microbunch, phase synchronized excitation of medium followed by its relaxation with a radiation of a single-cycled optical pulse, excitation of entanglement states in the medium of atoms with few valence electrons, and possibly other new phenomena, yet to be identified. Simple estimation of coherent ionization losses shows that a 100 MeV, 100 attosecond electron pulse containing 105 electrons will lose its total energy after propagating only ∼ 200(micro)m through liquid hydrogen. This is approximately 104 times shorter stopping range than it is for a long (on atomic scale) electron bunch

  10. Bunching of temporal cavity solitons via forward Brillouin scattering

    CERN Document Server

    Erkintalo, Miro; Jang, Jae K; Coen, Stéphane; Murdoch, Stuart G

    2015-01-01

    We report on the experimental observation of bunching dynamics with temporal cavity solitons in a continuously-driven passive fibre resonator. Specifically, we excite a large number of ultrafast cavity solitons with random temporal separations, and observe in real time how the initially random sequence self-organizes into regularly-spaced aggregates. To explain our experimental observations, we develop a simple theoretical model that allows long-range acoustically-induced interactions between a large number of temporal cavity solitons to be simulated. Significantly, results from our simulations are in excellent agreement with our experimental observations, strongly suggesting that the soliton bunching dynamics arise from forward Brillouin scattering. In addition to confirming prior theoretical analyses and unveiling a new cavity soliton self-organization phenomenon, our findings elucidate the manner in which sound interacts with large ensembles of ultrafast pulses of light.

  11. Longitudinal Single Bunch Instability Caused by Wake Field of Electron Cloud

    Institute of Scientific and Technical Information of China (English)

    LIU Yu-Dong; YU Cheng-Hui

    2009-01-01

    The electron cloud accumulated in the vicinity of positron beam generates longitudinal electric field during the passage of bunch. The longitudinal interaction between bunch and electron cloud can lead to the distortion of the bunch shape. We use a simple analytic formula to calculate the longitudinal electric field due to electron cloud. Based on the longitudinal wake field, the macro-particle tracking method is used to simulate the variation of bunch longitudinal profile in different electron cloud densities and the simulation also shows that the synchrotron oscillation tune is slightly shifted by the wake field. By comparing the simulation results and the analytical estimation from potential distortion theory, the longitudinal wake field from electron cloud can be seen as a potential well effect.

  12. Vertical coherent instabilities in bunched particle-beams

    International Nuclear Information System (INIS)

    The purpose of this paper is to study the vertical coherent instabilities which occur in bunched particle beams. The problem is complicated by the fact that the velocity of a single particle in a bunch is not constant, but rather consists of an equilibrium velocity and an oscillation about that. This synchrotron oscillation occurs at a frequency which is in general much less than the other characteristic frequencies of the system: the revolution frequency and the transverse betatron frequencies. The approach used here to study coherent instabilities illuminates the effect of the synchrotron frequency in setting the time scale for an instability, without making restrictive assumptions on the relative size of the synchrotron frequency and the coherent frequency shift

  13. Torrefaction of Pelletized Oil Palm Empty Fruit Bunches

    CERN Document Server

    Nyakuma, Bemgba Bevan; Johari, Anwar; Abdullah, Tuan Amran Tuan; Oladokun, Olagoke

    2015-01-01

    The torrefaction of oil palm Empty Fruit Bunch (EFB) briquettes was examined in this study. The results indicate that temperature significantly influenced the mass yield, energy yield and heating value of oil palm empty fruit bunch (OPEFB) briquettes during torrefaction. The solid uniform compact nature of EFB briquettes ensured a slow rate of pyrolysis or devolatization which enhanced torrefaction. The mass yield decreased from 79.70 % to 43.03 %, energy yield from 89.44 % to 64.27 % during torrefaction from 250 {\\deg}C to 300 {\\deg}C. The heating value (HHV) of OPEFB briquettes improved significantly from 17.57 MJ/kg to 26.24 MJ/kg after torrefaction at 300 {\\deg}C for 1 hour. Fundamentally, the study has highlighted the effects of pelletization and torrefaction on solid fuel properties of oil palm EFB briquettes and its potential as a solid fuel for future thermal applications.

  14. Simulation of intense beam bunching using 3D PIC method

    International Nuclear Information System (INIS)

    Most of the ion sources produce continuous beam of charged particles. In a cyclotron using such an external ion source, only a small fraction of the injected continuous beam is accepted in the central region for further acceleration. By transforming the continuous beam into a suitably bunched beam using a buncher prior to injection, the amount of accepted particles in the central region of cyclotron can be increased. To compress the continuous beam longitudinally one needs to impose a velocity modulation at the buncher gap which results in density modulation as the beam advances. In the case of low beam current the velocity modulation of the beam has very little effect on the transverse envelope of the beam. However, in the case of high intensity beams, the space-charge force introduces much collective behaviour and increase of current in the specified bunch width affects the transverse dynamics

  15. Emittance preservation during bunch compression with a magnetized beam

    Science.gov (United States)

    Stratakis, Diktys

    2016-03-01

    The deleterious effects of coherent synchrotron radiation (CSR) on the phase-space and energy spread of high-energy beams in accelerator light sources can significantly constrain the machine design and performance. In this paper, we present a simple method to preserve the beam emittance by means of using magnetized beams that exhibit a large aspect ratio on their transverse dimensions. The concept is based in combining a finite solenoid field where the beam is generated with a special optics adapter. Numerical simulations of this new type of beam source show that the induced phase-space density growth from CSR can be notably suppressed to less than 1% for any bunch charge. This work elucidates the key parameters that are needed for emittance preservation, such as the required field and aspect ratio for a given bunch charge.

  16. Compensating tune spread induced by space charge in bunched beams

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko, V.; Wang, G.

    2015-05-03

    The effects of space charge play a significant role in modern-day accelerators, frequently constraining the beam parameters attainable in an accelerator or in an accelerator chain. They also can limit the luminosity of hadron colliders operating either at low energies or with sub-TeV high-brightness hadron beams. The latter is applied for strongly cooled proton and ion beams in eRHIC – the proposed future electron-ion collider at Brookhaven National Laboratory. Using an appropriate electron beam would compensate both the tune shift and the tune spread in the hadron beam in a coasting beam. But these methods cannot compensate space charge tune spread in a bunched hadron beam. In this paper we propose and evaluate a novel idea of using a co-propagating electron bunch with mismatched longitudinal velocity to compensate the space charge induced tune-shift and tune spread.

  17. Development of multi-bunch beam energy compensation method

    International Nuclear Information System (INIS)

    A method to compensate for beam loading effects in a multi-bunch beam is under development at Accelerator Test Facility (ATF) in KEK. In this paper we describe the rf high power test for ΔT energy compensation by using the SLED cavities. In this ΔT (early injection and amplitude modulation) energy compensation method, the input waveform into accelerating structure is changed by controlling the rf phase and combining the rf-power from two klystrons with a 3 dB hybrid combiner to compensate multi-bunch beam energy for various beam currents. In this test, an arbitrary waveform was generated by changing the rotating speed of the each klystron phase into the opposite direction and the beam test will be done soon. (author)

  18. Emittance preservation during bunch compression with a magnetized beam

    Energy Technology Data Exchange (ETDEWEB)

    Stratakis, Diktys [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-09-02

    The deleterious effects of coherent synchrotron radiation (CSR) on the phase-space and energy spread of high-energy beams in accelerator light sources can significantly constrain the machine design and performance. In this paper, we present a simple method to preserve the beam emittance by means of using magnetized beams that exhibit a large aspect ratio on their transverse dimensions. The concept is based on combining a finite solenoid field where the beam is generated together with a special optics adapter. Numerical simulations of this new type of beam source show that the induced phase-space density growth can be notably suppressed to less than 1% for any bunch charge. This work elucidates the key parameters that are needed for emittance preservation, such as the required field and aspect ratio for a given bunch charge.

  19. Beam diagnostics based on time-domain bunch-by-bunch data

    Energy Technology Data Exchange (ETDEWEB)

    Teytelman, D.; Fox, J.; Hindi, H.; Limborg, C.; Linscott, I.; Prabhakar, S.; Sebek, J.; Young, A. [Stanford Linear Accelerator Center P.O. Box 4349 Stanford, California 94309 (United States); Drago, A.; Serio, M. [INFN-Laboratori Nazionali di Frascati, P.O. Box 13 I-00044 Frascati (Roma) (Italy); Barry, W.; Stover, G. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road Berkeley, California 94563 (United States)

    1998-12-01

    A bunch-by-bunch longitudinal feedback system has been used to control coupled-bunch longitudinal motion and study the behavior of the beam at ALS, SPEAR, PEP-II, and DA{Phi}NE. Each of these machines presents unique challenges to feedback control of unstable motion and data analysis. Here we present techniques developed to adapt this feedback system to operating conditions at these accelerators. A diverse array of techniques has been developed to extract information on different aspects of beam behavior from the time-domain data captured by the feedback system. These include measurements of growth and damping rates of coupled-bunch modes, bunch-by-bunch current monitoring, measurements of bunch-by-bunch synchronous phases and longitudinal tunes, and beam noise spectra. A technique is presented which uses the longitudinal feedback system to measure transverse growth and damping rates. Techniques are illustrated with data acquired at all of the four above-mentioned machines. {copyright} {ital 1998 American Institute of Physics.}

  20. Extremely short relativistic-electron-bunch generation in the laser wakefield via novel bunch injection scheme

    NARCIS (Netherlands)

    Khachatryan, A.G.; Goor, van F.A.; Boller, K.-J.; Reitsma, A.J.W.; Jaroszynski, D.A.

    2004-01-01

    Recently a new electron-bunch injection scheme for the laser wakefield accelerator has been proposed [JETP Lett. 74, 371 (2001); Phys. Rev. E 65, 046504 (2002)]. In this scheme, a low energy electron bunch, sent in a plasma channel just before a high-intensity laser pulse, is trapped in the laser wa

  1. Beam diagnostics based on time-domain bunch-by-bunch data

    International Nuclear Information System (INIS)

    A bunch-by-bunch longitudinal feedback system has been used to control coupled-bunch longitudinal motion and study the behavior of the beam at ALS, SPEAR, PEP-II, and DAΦNE. Each of these machines presents unique challenges to feedback control of unstable motion and data analysis. Here we present techniques developed to adapt this feedback system to operating conditions at these accelerators. A diverse array of techniques has been developed to extract information on different aspects of beam behavior from the time-domain data captured by the feedback system. These include measurements of growth and damping rates of coupled-bunch modes, bunch-by-bunch current monitoring, measurements of bunch-by-bunch synchronous phases and longitudinal tunes, and beam noise spectra. A technique is presented which uses the longitudinal feedback system to measure transverse growth and damping rates. Techniques are illustrated with data acquired at all of the four above-mentioned machines. copyright 1998 American Institute of Physics

  2. Design And Verification of Controllers for Coupled Bunch Instabilities Using Optimal Control Theory And Numerical Simulation: Predictions for PEP II

    Energy Technology Data Exchange (ETDEWEB)

    Hindi, Haitham; Prabhakar, Shyam; Fox, John D.; Linscott, Ivan; Teytelman, Dmitri; /SLAC

    2011-08-31

    We present a technique for the design and verification of efficient bunch-by-bunch controllers for damping longitudinal multibunch instabilities. The controllers attempt to optimize the use of available feedback amplifier power - one of the most expensive components of a feedback system - and define the limits of the closed loop system performance. Our design technique alternates between analytic computation of single bunch optimal controllers and verification on a multibunch numerical simulator. The simulator uses PEP-II parameters and identifies unstable coupled bunch modes, their growth rates and their damping rates with feedback. The results from the simulator are shown to be in reasonable agreement with analytical calculations based on the single bunch model. The technique is then used to evaluate the performance of a variety of controllers proposed for PEP-II.

  3. Transformer ratio studies for single bunch plasma wakefield acceleration

    International Nuclear Information System (INIS)

    In Plasma Wakefield Acceleration (PWFA) plasma oscillations are driven by ultra relativistic electron beams. The ratio of the maximum accelerating field behind the driving beam (bunch) and the maximum decelerating field inside the driving beam (bunch) is defined as Transformer Ratio, a key parameter that determines the energy gain in particle acceleration. We investigate the transformer ratio for different shapes of a single driving bunch. One dimensional, fluid, relativistic, cold plasma equations have been numerically solved. A complete map of the transformer ratio is obtained by varying: bunch shape, bunch length and density ratio. It is found that the transformer ratio critically depends on the bunch shape and on the density ratio. Moreover both in the linear as well as in the non-linear regime the theoretical limit of 2 for the transformer ratio of a single symmetric bunch can be exceeded using asymmetric bunches in the linear regime as well as symmetric bunches in nonlinear regime

  4. Real-time single-shot electron bunch length measurements

    International Nuclear Information System (INIS)

    Linear accelerators employed as drivers for X-ray free electron lasers (FELs) require relativistic electron bunch with sub-picosecond bunch length. Precise bunch length measurements are important for the tuning and operation of the FELs. Previously, we have demonstrated that electro-optic detection is a powerful technique for sub-picosecond electron bunch length measurements. In those experiments, the measured bunch length was the average of all electron bunches within a macropulse. Here, for the first time, we present the measurement of the length of individual electron bunches using a development of our previous technique. In this experiment, the longitudinal electron bunch shape is encoded electro-optically on to the frequency spectrum of a chirped laser pulse. Subsequently, the laser pulse is dispersed by a grating and the spectrum is imaged with a CCD camera. Single bunch measurements are achieved by using a nanosecond gated camera, and synchronizing the gate with both the electron bunch and the laser pulse repetition rates. The electron bunch length is determined by measuring the laser pulse spectra with and without the presence of an electron bunch. We demonstrate that this method enables a real-time diagnostic for the bunch length of single electron bunches with a time resolution of 370 femtoseconds and a high signal-noise-ratio

  5. Preliminary Study on Two Possible Bunch Compression Schemes at NLCTA

    International Nuclear Information System (INIS)

    lasing coherently in an undulator, one needs a very bright beam in all three dimensions. In other words, one needs an electron beam with very short bunch length (high intensity), very small transverse emittance and very small energy spread. Most FELs currently being operated, commissioned, constructed or proposed are based on RF acceleration in a frequency range from L-band ( 1 GHz) to C-band ( 6 GHz). As RF frequency goes higher, wake fields effects tend to be much stronger and jitter tolerances are tighter. To demonstrate that X-band acceleration structures can be applied in constructing an FEL, one could perform bunch compression experiments at NLCTA as a first step, and investigate tolerances on timing jitter, misalignments etc.. Another important point is to evaluate the transverse emittance growth in this bunch compression process. In the following sections, two possible bunch compression schemes are proposed to be tested at NLCTA. Elegant (4) 3-D simulation is performed to evaluate these two schemes, with wake fields, space charge and coherent synchrotron radiation (CSR) effects included. One million macro particles are adopted in the numerical simulations. The simulation starts with an electron beam of 20 pC at a beam energy of 5 MeV. The initial RMS bunch length is taken as 0.5 ps at such a low bunch charge, and the RMS energy spread is 5 x 10-3. The normalized transverse emittance is 1 mm.mrad.

  6. A coupled bunch instability due to beam-photoelectron interactions in KEKB-LER

    Energy Technology Data Exchange (ETDEWEB)

    Ohmi, Kazuhito [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

    1996-08-01

    LER of KEKB is designed to storage the positron beam of 2.6 A with multibunch operation. Nb = 3.3 x 10{sup 10} positrons are filled in a bunch and the bunch passes every 2ns through a beam chamber. The photoelectron instability may be serious for KEKB-LER. We consider a motion of photoelectrons produced by a bunch with a computer simulation technic. A cylindrical chamber with a diameter of 10 cm was used as a model chamber. About 15 times of the photoelectrons were produced by a bunch. The wake force was calculated for the loading bunches with displacements of 0.5 mm and 1 mm. The wake characteristics seems to be caused by the trapped electrons kicked by the loading bunch. The wake was saturated with the loading displacement of 0.5 mm. We obtained a growth rate by the wake force. It is very high rate, 2500s{sup -1} which exceeds damping rates of various mechanism, radiation, head-tail and feedback. Perhaps it is essential to remove the photoelectrons around the positron beam explicitly. If we apply magnetic field fo about 20 G, the growth rate will be reduced. (S.Y.)

  7. Excitation of Intra-bunch Vertical Motion in the SPS - Implications for Feedback Control of Ecloud and TMCI Instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Cesaratto, J.M.; Fox, J.D.; Pivi, M.T.; Rivetta, C.H.; Turgut, O.; Uemura, S.; /SLAC; Hofle, W.; Wehrle, U.; /CERN

    2012-06-01

    Electron cloud (ecloud) and transverse mode coupled-bunch instabilities (TMCI) limit the bunch intensity in the CERN SPS. This paper presents experimental measurements in the SPS of single-bunch motion driven by a GHz bandwidth vertical excitation system. The final goal is to quantify the change in internal bunch dynamics as instability thresholds are approached, and quantify the frequencies of internal modes as ecloud effects become significant. Initially, we have been able to drive the beam and view its motion. We show the excitation of barycentric, head-tail and higher vertical modes at different bunch intensities. The beam motion is analyzed in the time domain, via animated presentations of the sampled vertical signals, and in the frequency domain, via spectrograms showing the modal frequencies vs. time. The demonstration of the excitation of selected internal modes is a significant step in the development of the feedback control techniques.

  8. New method of beam bunching in free-ion lasers

    International Nuclear Information System (INIS)

    An effective ion beam bunching method is suggested. This method is based on a selective interaction of line spectrum laser light (e.g. axial mode structure light) with non-fully stripped ion beam cooled in a storage rings, arranging the ion beam in layers in radial direction of an energy-longitudinal coordinate plane and following rotation of the beam at the right angle after switching on the RF cavity or undulator grouper/buncher. Laser cooling of the ion beam can be used at this position after switching off the resonator to decrease the energy spread caused by accelerating field of the resonator. A relativistic multilayer ion mirror will be produced this way. Both monochromatic laser beams and intermediate monochromaticity and bandwidth light sources of spontaneous incoherent radiation can be used for production of hard and high power electromagnetic radiation by reflection from this mirror. The reflectivity of the mirror is rather high because of the cross-section of the backward Rayleigh scattering of photon light by non-fully stripped relativistic ions (∼λ2) is much greater (∼ 10 divided-by 15 orders) then Thompson one (∼ re2). This position is valid even in the case of non-monochromatic laser light (Δω/ω ∼ 10-4). Ion cooling both in longitudinal plane and three-dimensional radiation ion cooling had been proposed based on this observation. The using of these cooling techniques will permit to store high current and low emittance relativistic ion beams in storage rings. The bunched ion beam can be used in ordinary Free-Ion Lasers as well. After bunching the ion beam can be extracted from the storage ring in this case. Storage rings with zero momentum compaction function will permit to keep bunching of the ion beam for a long time

  9. New method of beam bunching in free-ion lasers

    Energy Technology Data Exchange (ETDEWEB)

    Bessonov, E.G. [Lebedev Physics Institute, Moscow (Russian Federation)

    1995-12-31

    An effective ion beam bunching method is suggested. This method is based on a selective interaction of line spectrum laser light (e.g. axial mode structure light) with non-fully stripped ion beam cooled in a storage rings, arranging the ion beam in layers in radial direction of an energy-longitudinal coordinate plane and following rotation of the beam at the right angle after switching on the RF cavity or undulator grouper/buncher. Laser cooling of the ion beam can be used at this position after switching off the resonator to decrease the energy spread caused by accelerating field of the resonator. A relativistic multilayer ion mirror will be produced this way. Both monochromatic laser beams and intermediate monochromaticity and bandwidth light sources of spontaneous incoherent radiation can be used for production of hard and high power electromagnetic radiation by reflection from this mirror. The reflectivity of the mirror is rather high because of the cross-section of the backward Rayleigh scattering of photon light by non-fully stripped relativistic ions ({approximately}{lambda}{sup 2}) is much greater ({approximately} 10{divided_by}15 orders) then Thompson one ({approximately} r{sub e}{sup 2}). This position is valid even in the case of non-monochromatic laser light ({Delta}{omega}/{omega} {approximately} 10{sup -4}). Ion cooling both in longitudinal plane and three-dimensional radiation ion cooling had been proposed based on this observation. The using of these cooling techniques will permit to store high current and low emittance relativistic ion beams in storage rings. The bunched ion beam can be used in ordinary Free-Ion Lasers as well. After bunching the ion beam can be extracted from the storage ring in this case. Storage rings with zero momentum compaction function will permit to keep bunching of the ion beam for a long time.

  10. Modulated electron bunch with amplitude front tilt in an undulator

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2015-12-15

    In a previous paper we discussed the physics of a microbunched electron beam kicked by the dipole field of a corrector magnet by describing the kinematics of coherent undulator radiation after the kick. We demonstrated that the effect of aberration of light supplies the basis for understanding phenomena like the deflection of coherent undulator radiation by a dipole magnet. We illustrated this fact by examining the operation of an XFEL under the steady state assumption, that is a harmonic time dependence. We argued that in this particular case the microbunch front tilt has no objective meaning; in other words, there is no experiment that can discriminate whether an electron beam is endowed with a microbunch front tilt of not. In this paper we extend our considerations to time-dependent phenomena related with a finite electron bunch duration, or SASE mode of operation. We focus our attention on the spatiotemporal distortions of an X-ray pulse. Spatiotemporal coupling arises naturally in coherent undulator radiation behind the kick, because the deflection process involves the introduction of a tilt of the bunch profile. This tilt of the bunch profile leads to radiation pulse front tilt, which is equivalent to angular dispersion of the output radiation. We remark that our exact results can potentially be useful to developers of new generation XFEL codes for cross-checking their results.

  11. On the coherent radiation of an electron bunch moving in an arc of a circle

    International Nuclear Information System (INIS)

    Existing theories of coherent synchrotron radiation (CSR) are related to the motion of an electron bunch on a circular orbit and do not describe the case of finite magnet length. We present the CSR theory for a bunch of any length moving in an arc of a finite angle. The radiative interaction of the electrons in the bunch is analyzed for a line charge distribution using ultrarelativistic approximation. It is shown in particular that this interaction is important not only inside the magnet but also on the straight part of the trajectory after the magnet. Detailed analytical study of the CSR effects in the electron bunch with a stepped distribution of the charge density has been performed. The simple analytical technique of the radiative force calculation has been developed. The analytical solutions in the form of elementary functions are obtained for the radiative interaction force, for the energy loss distribution along the bunch and for the total energy loss of the bunch. The latter result is confirmed with calculation of the energy of coherent radiation in far zone. The criterion for the applicability region of the preceding theories to the case of a finite magnet length is obtained

  12. Preliminary measurements of the bunch length and the impedance of LEP

    International Nuclear Information System (INIS)

    Measurements of the bunch length as function of current with a pick-up button yield data which seem to violate Robinson's sum rule for the damping partition numbers, even when the corrections for cable length and risetime of the sampling scope are applied. Measuring the bunch length as function of RF voltage gives an estimate of the total correction, including the response of the pick-ups and the feedthroughs. Simultaneous measurements of the bunch length and the horizontal emittance as functions of the RF frequency yield the variations of the damping partition numbers and hence the damping aperture. This can be used to estimate the RF frequency for which the orbit passes through the centers of the quadrupoles, and hence permits an absolute energy calibration of LEP. The threshold current for turbulent bunch lengthening yields an effective impedance of only 20 mOhms for the short bunches below threshold. Assuming a broad-band resonator with a resonant frequency of 2 GHz, this corresponds to a low frequency inductance Z/n of about 1/4 Ohm. First measurements of the shift of the longitudinal quadrupole mode with current agree quite well with these values. The transverse impedance has been obtained from the tune shift with current. Comparing horizontal and vertical shifts, the contributions of RF cavities and bellows can be separated. Although the threshold for transverse mode-coupling could not be measured yet, it is still expected to be near 3 mA in 4 (lengthened) bunches

  13. An ion source with bunched beam release

    International Nuclear Information System (INIS)

    As a continuation of a preceding study, the possibility of bunched beam release from a FEBIAD-B2 ion source was investigated for the alkali metals, the alkaline-earths, aluminum, the transition elements scandium to nickel and for ytterbium. With an appropriate choice of the cooling/heating system and of the trap material, efficient bunching is reached for the alkalies, calcium, manganese and ytterbium, which have enthalpies of adsorption within the range 2.6 ≤ΔH, < 5 eV, the window useful for bunching. Utilizing deduced values of the mean sticking time at a surface of defined temperature, ΔH/sub a/-values up to approximately 6 eV can be determined. Thus the conditions can be specified which should allow bunching and chemical separation for various other elements that are too refractory for the present device. Experimental and semi-empirical ΔH/sub a/-values are in good agreement for the transition elements and aluminium but exhibit strong deviations for the alkali metals, the alkaline-earths, ytterbium and probably some other lanthanides. On-line mass separation of neutron-deficient isotopes of cadmium, indium and tin with a high degree of selectivity demonstrates the chemical separation power of bunched beam release

  14. ''High intensity per bunch'' working group

    International Nuclear Information System (INIS)

    Third Generation Light Sources are supposed to store high intensity beams not only in many tightly spaced bunches (multibunch operation), but also in few bunch or even single lunch modes of operation, required for example for time structure experiments. Single bunch instabilities, driven by short-range wake fields, however spoil the beam quality, both longitudinally and transversely. Straightforward ways of handling them, by pushing up the chromaticity (ζ = ΔQ/(Δp/p)) for example, enabled to raise the charge per bunch, but to the detriment of beam lifetime. In addition, since the impedance of the vacuum chamber deteriorates with the installation of new insertion devices, the current thresholds tend to dope down continuously. The goal of this Working Group was then to review these limitations in the existing storage rings, where a large number of beam measurements have been performed to characterise them, and to discuss different strategies which are used against them. About 15 different laboratories reported on the present performance of storage rings, experiences gained in high charge per bunch, and on simulation results and theoretical studies. More than 25 presentations addressed the critical issues and stimulated the discussion. Four main topics came out: - Observation and experimental data; - Impedance studies and tracking codes; - Theoretical investigations; - Cures and feedback. (author)

  15. Measurement of bunch length at TRISTAN MR

    International Nuclear Information System (INIS)

    The bunch length was measured at the injection energy of 8 GeV in the TRISTAN Main Ring (MR) with two methods. One method is to measure a longitudinal profile of the synchrotron light using a streak camera, and the other uses a technology based on detecting the beam spectrum. A bunch shortening was observed in low beam currents with both methods. On the other hand, the bunch shape was much distorted from a Gaussian at higher currents. A big disparity in the measurements between the spectrum method and the FWHM of a profile was observed there. A comparison among the spectrum method, the FWHM and the rms. value for non-Gaussian distributions was carried out in order to understand the disparity. (author)

  16. Note on polarized RHIC bunch arrangement

    International Nuclear Information System (INIS)

    We discuss what combinations of bunch polarization in the two RHIC rings are necessary to do the physics measurements at various interaction regions. We also consider the bunches for both the pion inclusive and p-p elastic polarization measurements. Important factors to consider are the direction of the polarization with respect to the momentum in each bunch, the beam gas backgrounds, and the simulation of zero - polarization in one beam by averaging + and - helicity, and luminosity monitoring for normalization. These considerations can be addressed by setting the relative number of each of the 9 combinations possible at each of the 6 interaction regions. The combinations are (+ empty -) yellow X (+ empty -)blue, where yellow and blue are the counter-rotating rings

  17. Wake fields excited in a micron-scale dielectric rectangular structure by a train of femtosecond bunches

    International Nuclear Information System (INIS)

    We study the longitudinal wake field components which are induced in a rectangular, dielectric-lined structure having micron-scale dimensions by the passage of one or more charge bunches having femtosecond duration. The bunches would be obtained from a 500 MeV LACARA 'chopper' which uses a TW optical wave from a CO2 laser; the bunches are chopped from a macrobunch having duration ∼1 psec obtained from a high brightness 500 MeV rf linac. The high intensity laser wave accomplishes the chopping of the macrobunch into slices which are roughly 10% of the 10.6 μm radiation wavelength. These microbunches can be shaped into a rectangular cross section, approximately 10 μm x 150 μm in dimension, and will excite wake fields when injected into a rectangular dielectric wake field accelerating structure. We compute sample 3D wake fields, using the PIC code KARAT, as well as by means of an analytic method. The passage of just one pC bunch will set up a longitudinal wake field ∼ 40 MeV/m, and a train of ten properly-timed such bunches can produce a cumulative wake field ∼ 600 MeV/m. The choice of dimensions causes the wave solutions to approximate a single-mode excited by an infinitely-tall bunch in a 2D structure; a highly uniform longitudinal wake field in the cross-sectional plane of the structure results, suitable for accelerating a correctly positioned 'test bunch'. KARAT includes the effect of interference between the Cerenkov radiation of the bunch with the transition radiation emitted as the bunch enters the structure. The wake field structure is several cm in length, and is both rigid and capable of microfabrication accuracy; it could accordingly be a reproducible module in a staged array. The stability of the bunches and the analytic formulation are dealt with in a companion paper

  18. Wake Fields Excited in a Micron-Scale Dielectric Rectangular Structure by a Train of Femtosecond Bunches

    Science.gov (United States)

    Marshall, T. C.; Fang, J.-M.; Hirshfield, J. L.; Wang, Changbiao; Tarakanov, V. P.; Park, S. Y.

    2002-12-01

    We study the longitudinal wake field components which are induced in a rectangular, dielectric-lined structure having micron-scale dimensions by the passage of one or more charge bunches having femtosecond duration. The bunches would be obtained from a 500 MeV LACARA "chopper" which uses a TW optical wave from a CO2 laser [1]; the bunches are chopped from a macrobunch having duration ˜1 psec obtained from a high brightness 500 MeV rf linac. The high intensity laser wave accomplishes the chopping of the macrobunch into slices which are roughly 10% of the 10.6 μm radiation wavelength. These microbunches can be shaped into a rectangular cross section, approximately 10 μm × 150 μm in dimension, and will excite wake fields when injected into a rectangular dielectric wake field accelerating structure. We compute sample 3D wake fields, using the PIC code KARAT, as well as by means of an analytic method. The passage of just one pC bunch will set up a longitudinal wake field ˜ 40 MeV/m, and a train of ten properly-timed such bunches can produce a cumulative wake field ˜ 600 MeV/m. The choice of dimensions causes the wave solutions to approximate a single-mode excited by an infinitely-tall bunch in a 2D structure; a highly uniform longitudinal wake field in the cross-sectional plane of the structure results, suitable for accelerating a correctly positioned "test bunch". KARAT includes the effect of interference between the Cerenkov radiation of the bunch with the transition radiation emitted as the bunch enters the structure. The wake field structure is several cm in length, and is both rigid and capable of microfabrication accuracy; it could accordingly be a reproducible module in a staged array. The stability of the bunches and the analytic formulation are dealt with in a companion paper [2].

  19. Dancing bunches as Van Kampen modes

    CERN Document Server

    Burov, A

    2012-01-01

    Van Kampen modes are eigen-modes of Jeans-Vlasov equation. Their spectrum consists of continuous and, possibly, discrete parts. Onset of a discrete van Kampen mode means emergence of a coherent mode without any Landau damping; thus, even a tiny couple-bunch wake is sufficient to drive instability. Longitudinal instabilities observed at Tevatron, RHIC and SPS can be explained as loss of Landau damping (LLD), which is shown here to happen at fairly low impedances. For repulsive wakes and single-harmonic RF, LLD is found to be extremely sensitive to steepness of the bunch distribution function at small amplitudes. Based on that, a method of beam stabilization is suggested.

  20. Effect of physical and chemical properties of oil palm empty fruit bunch, decanter cake and sago pith residue on cellulases production by Trichoderma asperellum UPM1 and Aspergillus fumigatus UPM2.

    Science.gov (United States)

    Zanirun, Zuraidah; Bahrin, Ezyana Kamal; Lai-Yee, Phang; Hassan, Mohd Ali; Abd-Aziz, Suraini

    2014-01-01

    The effect of cultivation condition of two locally isolated ascomycetes strains namely Trichoderma asperellum UPM1 and Aspergillus fumigatus UPM2 were compared in submerged and solid state fermentation. Physical evaluation on water absorption index, solubility index and chemical properties of lignin, hemicellulose and cellulose content as well as the cellulose structure on crystallinity and amorphous region of treated oil palm empty fruit bunch (OPEFB) (resulted in partial removal of lignin), sago pith residues (SPR) and oil palm decanter cake towards cellulases production were determined. Submerged fermentation shows significant cellulases production for both strains in all types of substrates. Crystallinity of cellulose and its chemical composition mainly holocellulose components was found to significantly affect the total cellulase synthesis in submerged fermentation as the higher crystallinity index, and holocellulose composition will increase cellulase production. Treated OPEFB apparently induced the total cellulases from T. asperellum UPM1 and A. fumigatus UPM2 with 0.66 U/mg FPase, 53.79 U/mg CMCase, 0.92 U/mg β-glucosidase and 0.67 U/mg FPase, 47.56 U/mg and 0.14 U/mg β-glucosidase, respectively. Physical properties of water absorption and solubility for OPEFB and SPR also had shown significant correlation on the cellulases production. PMID:24085387

  1. Coherent synchrotron radiation and bunch stability in a compact storage ring

    International Nuclear Information System (INIS)

    We examine the effect of the collective force due to coherent synchrotron radiation (CSR) in an electron storage ring with small bending radius. In a computation based on time-domain integration of the nonlinear Vlasov equation, we find the threshold current for a longitudinal microwave instability induced by CSR alone. The model accounts for suppression of radiation at long wave lengths due to shielding by the vacuum chamber. In a calculation just above threshold, small ripples in the charge distribution build up over a fraction of a synchrotron period, but then die out to yield a relatively smooth but altered distribution with eventual oscillations in bunch length. The instability evolves from small noise on an initial smooth bunch of r.m.s.length much greater than the shielding cutoff. The paper includes a derivation and extensive analysis of the complete impedance function Z for synchrotron radiation with parallel plate shielding. We find corrections to the lowest approximation to the coherent force which involve ''off-diagonal'' values of Z, that is, fields with phase velocity not equal to the particle velocity

  2. Development of the bunch-by-bunch beam current acquisition system at SSRF

    Institute of Scientific and Technical Information of China (English)

    HUANG Siting; LENG Yongbin; YAN Yingbing

    2009-01-01

    In this paper, we report the development of a bunch-by-bunch beam current acquisition system. Through a waveform-reconstruction algorithm, the system realizes high equivalent sampling rate with a relatively low inherent rate. Based on the EPICS environment, information communication with other systems can be achieved. Preliminary test results in commissioning the SSRF storage ring show that the system can reconstruct the beam waveform of single bunch, providing a convenient and reliable method for the top-up operation in the future.

  3. Development of bunch by bunch transverse feedback system at Hefei light source

    International Nuclear Information System (INIS)

    This paper has introduced the development of the transverse bunch-by-bunch measurement and feedback system, including the experiment of damping the coupled bunch instability. Some key technologies on the system have been introduced: the vector calculation module as a signal processing module used to adjust the phase of the feedback signals, the feedback kicker cavity and the notch filter used to filter the DC component and revolution frequencies component in a signal and save the feedback power. The result of the feedback experiment is mentioned: the instability oscillation was damped when the feedback system was on. (authors)

  4. Short bunch wake potentials for a chain of TESLA cavities

    International Nuclear Information System (INIS)

    The modification of wake fields from a single cavity to a quasi-periodic structure of cavities is of great concern, especially for applications using very short bunches. We extend our former study (Novokhatski, 1997 [1]). A strong modification of wake fields along a train of cavities was clearly found for bunch lengths lower than 1 mm. In particular, the wakes induced by the bunch, as it proceeds down the successive cavities, decrease in amplitude and become more linear around the bunch center, with a profile very close to the integral of the charge density. The loss factor, decreasing also with the number of cells, becomes independent of bunch length for very short bunches and tends asymptotically to a finite value. This nice behavior of wake fields for short bunches presents good opportunity for application of very short bunches in Linear Colliders and X-ray Free Electron Lasers

  5. Bunch length measured by 20 GHz digital sampling oscilloscope

    International Nuclear Information System (INIS)

    The paper discusses the method and principle of bunch length measured using HP54121T 20 GHz digital sampling oscilloscope in Hefei Light Source (HLS) ring. The measurement result of the bunch length and its lengthening is given. The root of mean square for bunch length is about 3.80-10.33 cm at 2-124 mA beam current. As the beam current slop over 15 mA, the bunch lengthening is obvious

  6. Multi-bunch injection for SSRF storage ring

    CERN Document Server

    Jiang, Bocheng; Wang, Baoliang; Zhang, Manzhou; Yin, Chongxian; Yan, Yingbing; Tian, Shunqiang; Wang, Kun

    2015-01-01

    The multi-bunch injection has been adopt at SSRF which greatly increases the injection rate and reduces injection time compared to the single bunch injection. The multi-bunch injection will massively reduce the beam failure time during users operation and prolong pulsed injection hardware lifetime. In this paper, the scheme to produce multi bunches for the RF electron gun is described. The refilling result and the beam orbit stability for top up operation is discussed.

  7. Bunch Splitting Simulations for the JLEIC Ion Collider Ring

    Energy Technology Data Exchange (ETDEWEB)

    Satogata, Todd J. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Gamage, Randika [Old Dominion Univ., Norfolk, VA (United States)

    2016-05-01

    We describe the bunch splitting strategies for the proposed JLEIC ion collider ring at Jefferson Lab. This complex requires an unprecedented 9:6832 bunch splitting, performed in several stages. We outline the problem and current results, optimized with ESME including general parameterization of 1:2 bunch splitting for JLEIC parameters.

  8. 33 CFR 163.20 - Bunching of tows.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Bunching of tows. 163.20 Section... AND WATERWAYS SAFETY TOWING OF BARGES § 163.20 Bunching of tows. (a) In all cases where tows can be bunched, it should be done. (b) Tows navigating in the North and East Rivers of New York must be...

  9. A simple model of the slingshot effect

    CERN Document Server

    Fiore, Gaetano

    2015-01-01

    We present a detailed quantitative description of the recently proposed "slingshot effect" [Fiore, Fedele, De angelis 2014]. Namely, we determine a broad range of conditions under which the impact of a very short and intense laser pulse normally onto a plasma (or matter to be locally completely ionized into a plasma by the pulse) causes the expulsion of a bunch of surface electrons in the direction opposite to the one of propagation of the pulse, and the detailed, ready-for-experiments features of the expelled electrons (energy spectrum, collimation, etc). The effect is due to the combined actions of the ponderomotive force and the huge longitudinal field arising from charge separation. Our predictions are based on estimating 3D corrections to a simple, yet powerful plane magnetofluidodynamic model where the equations to be solved are reduced to a system of Hamilton equations in one dimension (or a collection of) which become autonomous after the pulse has overcome the electrons. Experimental tests seem to be...

  10. Charged particle acceleration with the wakefield fields in a dielectric resonator with a channel for exciting bunch

    International Nuclear Information System (INIS)

    The electrons acceleration with the wakefield fields, excited by the electron bunches sequence in the resonator, is studied. The resonator constitutes a section of the metallic cylindrical waveguide with a dielectric bush, the faces whereof are closed by the metallic walls. The expressions for the wakefield fields are obtained in the case of the assigned uniform motion of the exciting bunches. The numerical modelling of the resonator self-consistent excitation through the charged bunches sequence and particles acceleration in the excited fields is carried out

  11. Electron multipacting in long-bunch beam

    OpenAIRE

    Kai-Wei, Li

    2015-01-01

    The electron multipacting is an important factor for the development of the electron cloud. There is a trailing-edge multipacting in the tail of the long-bunch beam. It can be described by the energy gain and motion of electrons. The analyses are in agreement with the simulation.

  12. Adiabatic Excitation of Longitudinal Bunch Shape Oscillations

    International Nuclear Information System (INIS)

    By modulating the rf voltage at near twice the synchrotrons frequency we are able to modulate the longitudinal bunch shape. We show experimentally that this can be done while preserving the longitudinal emittance when the rf voltage modulation is turned on adiabatically. Experimental measurements will be presented along with theoretical predictions

  13. Generation of intensive terahertz radiation in structure by super short electron bunches

    International Nuclear Information System (INIS)

    For achievement of powerful radiation in terahertz range the theoretical research and numerical modeling of excitation of a wakefield the dielectric resonator by electron bunches is carried out. As the resonator the part of a metal waveguide in length of 0.145 sm, with the dielectric plug with internal radius 100 microns and external 140 microns which end faces are closed by metal walls has been chosen. On the basis of nonlinear equations system which are describes self-consisted interaction of charged bunches and an electromagnetic field excited by them, numerical modeling excitation of the resonator is lead.

  14. Measurements of Transverse Emittance Growth due to Coherent Synchrotron Radiation in the SLAC SPPS Bunch Compressor Chicane

    International Nuclear Information System (INIS)

    A four-dipole bunch compressor chicane has recently been installed in the SLAC linac at 9 GeV and is capable of compressing a 3.4-nC electron bunch to an rms length of 50 microns, resulting in a peak current of nearly 10 kA [1]. The electron bunch is extracted from a damping ring with normalized horizontal emittance of ∼ 30 (micro)m. We present preliminary measurements of the initial and final emittance in the chicane and compare these to 1D and 3D calculations of the effects of coherent synchrotron radiation (CSR)

  15. Laser diagnostics of micro bunches (old tricks, new games)

    International Nuclear Information System (INIS)

    The transverse shape and the length of micro bunches can be determined thanks to Compton scattering signals. Scanning the bunches across a laser-driven fringe pattern produces periodic modulations of the amount of scattered light, i.e. fringes whose visibility contains information on the electron transverse distribution. Through inverse Fourier transforms, even and odd parts of the profiles of bunches whose size compares with or is larger than the optical wavelength can be reconstructed. The method is suited for round and flat bunches. Methods of bunch length evaluation are also presented. copyright 1996 American Institute of Physics

  16. Numerical analysis of velocity bunching for an ERL light source

    International Nuclear Information System (INIS)

    We investigate feasibility of velocity bunching in the main linac of an energy recovery linac (ERL) by a computational simulation. The simulation performed for eight TESLA-type cavities reveals successful bunch compression from 3.2 ps to 170 fs, which is in good agreement with the analytical prediction. Since the residual energy spread after velocity bunching is considerably smaller than the correlated energy spread required for magnetic compression through recirculation, velocity bunching is useful to realize short-pulse and high-brightness X-rays by ERL. The beam current limitation on velocity bunching is also discussed

  17. Microbunching Due to Coherent Synchrotron Radiation in a Bunch Compressor

    International Nuclear Information System (INIS)

    The coherent synchrotron radiation of a bunch in a bunch compressor may lead to the microwave instability producing longitudinal modulation of the bunch. This modulation generates coherent radiation with the wave length small compared to the bunch length. It can also be a source of an undesirable emittance growth in the compressor. We derive and analyze the equation that describes linear evolution of the microwave modulation. Numerical solution of this equation for the LCLS bunch compressor reveals such an instability, in qualitative agreement with numerical simulations

  18. Space charge measurements with a high intensity bunch at the Fermilab Main Injector

    International Nuclear Information System (INIS)

    For Project X, the Fermilab Main Injector will be required to operate with 3 times higher bunch intensity. The plan to study the space charge effects at the injection energy with intense bunches will be discussed. A multi-MW proton facility has been established as a critical need for the U.S. HEP program by HEPAP and P5. Utilization of the Main Injector (MI) as a high intensity proton source capable of delivering in excess of 2 MW beam power will require a factor of three increase in bunch intensity compared to current operations. Instabilities associated with beam loading, space charge, and electron cloud effects are common issues for high intensity proton machines. The MI intensities for current operations and Project X are listed in Table 1. The MI provides proton beams for Fermilab's Tevatron Proton-Antiproton Collider and MINOS neutrino experiments. The proposed 2MW proton facility, Project X, utilizes both the Recycler (RR) and the MI. The RR will be reconfigured as a proton accumulator and injector to realize the factor 3 bunch intensity increase in the MI. Since the energy in the RR and the MI at injection will be 6-8 GeV, which is relatively low, space charge effects will be significant and need to be studied. Studies based on the formation of high intensity bunches in the MI will guide the design and fabrication of the RF cavities and space-charge mitigation devices required for 2 MW operation of the MI. It is possible to create the higher bunch intensities required in the MI using a coalescing technique that has been successfully developed at Fermilab. This paper will discuss a 5 bunch coalescing scheme at 8 GeV which will produce 2.5 x 1011 protons in one bunch. Bunch stretching will be added to the coalescing process. The required RF parameters were optimized with longitudinal simulations. The beam studies, that have a goal of 85% coalescing efficiency, were started in June 2010.

  19. Chromatic correction in the SLC bunch length compressors

    International Nuclear Information System (INIS)

    The SLC Ring to Linac (RTL) transport lines employ intense bending and strong transverse focusing to produce the momentum compaction needed for bunch length compression prior to S-band acceleration. In the presence of the large rf induced energy spread needed for compression the consequent chromatic effects -- viz. the variation with energy of residual output dispersion and of the RTL transfer matrix, threaten to destroy the small emittances produced by the damping rings. We report on the tuning methods that have been developed and used to implement the sextupole based chromatic correction scheme. 6 refs., 4 figs

  20. Chromatic correction in the SLC bunch length compressors

    Energy Technology Data Exchange (ETDEWEB)

    Adolphsen, C.E.; Emma, P.J.; Fieguth, T.H.; Spence, W.L.

    1991-06-01

    The SLC Ring to Linac (RTL) transport lines employ intense bending and strong transverse focusing to produce the momentum compaction needed for bunch length compression prior to S-band acceleration. In the presence of the large rf induced energy spread needed for compression the consequent chromatic effects -- viz. the variation with energy of residual output dispersion and of the RTL transfer matrix, threaten to destroy the small emittances produced by the damping rings. We report on the tuning methods that have been developed and used to implement the sextupole based chromatic correction scheme. 6 refs., 4 figs.

  1. Chromatic correction in the SLC bunch length compressors

    International Nuclear Information System (INIS)

    The SLC Ring to Linac (RTL) transport lines employ intense bending and strong transverse focusing to produce the momentum compaction needed for bunch length compression prior to S-band acceleration. In the presence of the large rf induced energy spread needed for compression the consequent chromatic effects - viz. the variation with energy of residual output dispersion and of the RTL transfer matrix, threaten to destroy the small emittances produced by the damping rings. The authors report on the tuning methods that have been developed and used to implement the sextupole based chromatic correction scheme

  2. Numerical simulation of the interaction between two high-energy plasma bunches in the ionosphere

    Science.gov (United States)

    Motorin, A. A.; Stupitsky, E. L.; Kholodov, A. S.

    2016-07-01

    The 3D MHD algorithm developed by us has been adapted to modeling the interaction between two plasma bunches in the ionosphere, mainly in order to sufficiently correctly describe the physics of the interaction between two plasma regions with regard to the ionospheric inhomogeneity and the geomagnetic field action. Modeling has been performed for several versions of location of the plasma region centers.

  3. Software development for Indus-1 bunch filling pattern measurement

    International Nuclear Information System (INIS)

    Indus-1 is a 450 MeV synchrotron radiation source operational at RRCAT Indore. In Indus-1 storage ring, electrons are stored in two bunches. The distribution of beam current in these two bunches is termed as bunch filling pattern. In Indus-1, it is desirable to have symmetric bunch filling pattern for its optimum performance. This paper describes the development of software for bunch filling pattern measurement of Indus-1. This software measures the current distribution of the electron bunches circulating in the storage ring. To measure bunch currents wall current monitor (WCM) installed in the Indus-1 storage ring is used. Using a 500 MHz digital storage oscilloscope as a high-speed digitizer and online data processing by the developed software, measurement of online bunch filling pattern was achieved. This software has helped Indus operation crew to achieve desired bunch current symmetry in the Indus-1 storage ring. The software has the provision to store the online bunch current symmetry into a Microsoft-excel file which can be used for further analysis. Using this software, up to 99% bunch filling symmetry has been achieved by Indus operation crew. (author)

  4. Controlling multi-bunches by a fast phase switching

    International Nuclear Information System (INIS)

    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+,e-) for the high energy collisions and one (e--scavenger) for producing positrons should sit at different phases, due to their different tasks. The two e--bunches are extracted from the damping ring at the same cycle time about 60 ns apart. Fast phase switching of the RF to the bunch length compressor in the Ring-To-Linac (RTL) section can produce the necessary advance of the scavenger bunch (about 6 degree in phase). This allows a low energy spread of this third bunch at the e+-production region at 2/3 of the linac length, while the other bunches are not influenced. The principles and possible other applications of this fast phase switching as using it for multi-bunches, as well as the experimental layout for the actual RTL compressor are presented

  5. Numerical modelling of Bose-Einstein correlations

    OpenAIRE

    Utyuzh, O. V.; Wilk, G.; Wlodarczyk, Z.

    2001-01-01

    We propose extension of the algorithm for numerical modelling of Bose-Einstein correlations (BEC), which was presented some time ago in the literature. It is formulated on quantum statistical level for a single event and uses the fact that identical particles subjected to Bose statistics do bunch themselves, in a maximal possible way, in the same cells in phase-space. The bunching effect is in our case obtained in novel way allowing for broad applications and fast numerical calculations. Firs...

  6. Ultrashort relativistic electron bunches and spatio-temporal radiation biology

    Science.gov (United States)

    Gauduel, Y. A.; Faure, J.; Malka, V.

    2008-08-01

    The intensive developments of terawatt Ti:Sa lasers permit to extend laser-plasma interactions into the relativistic regime, providing very-short electron or proton bunches. Experimental researches developed at the interface of laser physics and radiation biology, using the combination of sub-picosecond electron beams in the energy range 2-15 MeV with femtosecond near-IR optical pulses might conjecture the real-time investigation of penetrating radiation effects. A perfect synchronization between the particle beam (pump) and optical beam at 820 nm (probe) allows subpicosecond time resolution. This emerging domain involves high-energy radiation femtochemistry (HERF) for which the early spatial energy deposition is decisive for the prediction of cellular and tissular radiation damages. With vacuum-focused intensities of 2.7 x 1019 W cm-2 and a high energy electron total charge of 2.5 nC, radiation events have been investigated in the temporal range 10-13 - 10-10s. The early radiation effects of secondary electron on biomolecular sensors may be investigated inside sub-micrometric ionisation, considering the radial direction of Gaussian electron bunches. It is shown that short range electron-biosensor interactions lower than 10 A take place in nascent track structures triggered by penetrating radiation bunches. The very high dose delivery 1013 Gy s-1 performed with laser plasma accelerator may challenge our understanding of nanodosimetry on the time scale of molecular target motions. High-quality ultrashort penetrating radiation beams open promising opportunities for the development of spatio-temporal radiation biology, a crucial domain of cancer therapy, and would favor novating applications in nanomedicine such as highly-selective shortrange pro-drug activation.

  7. Preliminary Design of a Bunching System for the CLIC Polarized Electron Source

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Feng

    2009-10-30

    Major parameters of the CLIC and ILC electron sources are given in Table I. It is shown that the CLIC source needs to provide 312 15-ps-long 2-GHz microbunches. There are two approaches to achieve the time structure [2]: one is to develop a 2-GHz optical pulse train, and the other to develop a 156-ns-long CW optical pulse and use an RF bunching system to generate 312 2-GHz microbunches. The former scheme may ease the RF bunching system but still need it to bunch 100-ps of microbunch down to 15-ps level. Otherwise, a huge amount of energy spread is accumulated when the beam is accelerated through downstream 2-GHz accelerator. In addition, in the former scheme, the space charge is high and surface charge is not yet proven in the parameter regime and 2-GHz mode locked laser is challenging. The latter scheme needs a high-efficiency bunching system to generate 312 15-ps microbunches with 2-GHz repetition rate but it has some notable advantages: a 156-ns CW laser technique is matured, and the charge limit behavior in the scheme is better characterized than that in the former case, as listed in the table. This note presents a design and modeling of the bunching system for the latter scheme to convert a 156-ns CW pulse to 312 15-ps long 2-GHz microbunches.

  8. Consequences of centrifugally-driven phase bunching in the near-earth magnetotail

    Science.gov (United States)

    Delcourt, D. C.; Belmont, G.; Sauvaud, J.-A.; Moore, T. E.; Martin, R. F., Jr.

    1996-01-01

    The dynamics of the plasma sheet ions in the near-earth magnetotail where the Larmor radii are comparable to the magnetic field line curvature radius are examined. It is shown that enhanced centrifugal effects lead to the prominent bunching of the particles in the gyration phase. As a result of this bunching effect, it is demonstrated that a thin current sheet develops in the vicinity of the tail midplane. Using average values of the plasma density and temperature, the current sheet obtained has a characteristic thickness of the order of a few tenths of an earth radius, and leads to significant stretching of the local magnetic field lines. A further consequence of phase bunching is the build-up of a substantial current in the earth tail direction at low latitudes which leads to field line inclination in the dawn-dusk direction.

  9. Fast calculation of the resistive wall wake sum for multi bunch beams

    CERN Document Server

    Vogel, E

    2005-01-01

    For the numerical study of the beam injection process into the LHC, several technical and beam dynamical effects have to be taken into account, e.g. closed orbit variations of the pre-accelerator SPS, ripples on extraction and injection kickers, optics of the LHC itself and the behaviour of its transverse feedback system. Prominent beam dynamical effects are coupled bunch instabilities caused for example by the vacuum chamber resistance. This paper describes a fast approximate calculation of the beam deflection due to the wake field which is built up by the vacuum chamber resistance and caused by a large number of previous bunches and/or bunch passages. The code has been implemented into the framework of the CNGS extraction simulations [1] and the results are compared with measurements [2].

  10. Asymmetric two-bunch operation of free-electron laser and generation of inverse Compton photons

    International Nuclear Information System (INIS)

    Yield enhancement of high-energy photon pulses, which were generated via inverse Compton scattering of free-electron laser (FEL) pulses with electron pulses in relativistic motion, was achieved by an asymmetric two-bunch method. This method involves the use of two electron bunches recirculating in an electron storage ring for FEL oscillation with asymmetric bunch filling, and the generation of inverse Compton photon pulses at two collision points. The effects of the magnetic field of an undulator for FEL oscillation on the photon energy spectrum and photon yield were analyzed by Monte Carlo simulations and experiments. -- Highlights: ► Yield enhancement of inverse Compton γ rays is achieved. ► Effects of magnetic field on the γ rays are analyzed by theory and experiments. ► The energy spread of the γ ray increases and the intensity decreases.

  11. Observations of ''effective'' transverse beam-size instabilities for a high current per bunch fill pattern in the APS storage ring

    International Nuclear Information System (INIS)

    The x-ray pinhole camera diagnostics on the Advanced Photon Source (APS) storage ring have recorded an effective transverse beam size instability during operations with a sextuplet plus 22 singlets fill pattern. These instabilities were not observed with the sextuplet plus 25 triplets fill pattern that has been the standard fill pattern in FY'98. The instability threshold is at 82-85 mA with positrons. The features include an increased average (few seconds) transverse size both horizontally and vertically for stored currents above the threshold with a correlated effect on the beam lifetime. The horizontal transverse emittance is 25-30% larger at 100 mA than below the threshold. There is a related horizontal beam centroid motion as well, but this does not explain the vertical size change nor the lifetime effect. Complementary data were also taken with the diagnostic undulator, and a similar threshold effect on divergence was observed. The cross-comparison of the data and possible mechanisms is presented

  12. Bunch-to-bucket injection of linac beam into the Brookhaven AGS

    International Nuclear Information System (INIS)

    A new fast beam chopper has been used to study injection and capture in the AGS. The chopper is a fast beam switch with 10 ns rise and fall times that can be programmed on a bunch-by-bunch basis and is synchronized to the net accelerating voltage of the synchrotron, thus allowing bunch-to-bucket injection of the 200 MeV H- linac beam. The studies so far have concentrated on simple injection scenarios, at reduced intensity, where longitudinal effects are well separated from transverse. The evolution of the pre-bunched beam during the transition from injection to acceleration has been examined. Results have shown the importance of the detailed linac beam energy distribution. The ability to control the longitudinal emittance of the beam with the fast chopper has been used in other machine studies. This report includes a description of a measurement of the longitudinal coupling impedance of the AGS by the beam transfer function technique which utilized the control of longitudinal emittance provided by bunch-to-bucket injection. Plans for improvements to the chopper equipment are also describe. 6 refs., 4 figs

  13. Self-interaction of subpico-second electron bunch traveling through a chicane-based bunch-compressor

    International Nuclear Information System (INIS)

    A photo-cathode RF-gun and a chicane-based bunch-compressor are installed on an S-band linac which had been used for a UT-FEL experiment. Electron bunches extracted from the photo-cathode RF-gun are accelerated by an S-band structure up to 20 MeV and compressed by a chicane magnet. Since the bunch has very small longitudinal size and relatively low energy, coherent synchrotron radiation emitted from the bunch in the chicane creates a nonuniform energy loss in the bunch and degrades the performance of the bunch compressor. In the present paper, the performance of the bunch-compressor under the influence of coherent synchrotron radiation is studied. Preliminary experimental results are also presented

  14. Self-interaction of subpico-second electron bunch traveling through a chicane-based bunch-compressor

    CERN Document Server

    Hajima, R; Ueda, T; Sakai, F; Kotaki, H; Kondoh, S; Kando, M; Kinoshita, K; Harano, H; Watanabe, T; Uesaka, M; Dewa, H; Nakajima, K

    1999-01-01

    A photo-cathode RF-gun and a chicane-based bunch-compressor are installed on an S-band linac which had been used for a UT-FEL experiment. Electron bunches extracted from the photo-cathode RF-gun are accelerated by an S-band structure up to 20 MeV and compressed by a chicane magnet. Since the bunch has very small longitudinal size and relatively low energy, coherent synchrotron radiation emitted from the bunch in the chicane creates a nonuniform energy loss in the bunch and degrades the performance of the bunch compressor. In the present paper, the performance of the bunch-compressor under the influence of coherent synchrotron radiation is studied. Preliminary experimental results are also presented.

  15. Pickup design for high bandwidth bunch arrival-time monitors in free-electron lasers

    International Nuclear Information System (INIS)

    The increased demands for low bunch charge operation mode in the free-electron lasers (FELs) require an upgrade of the existing synchronization equipment. As a part of the laser-based synchronization system, the bunch arrival-time monitors (BAMs) should have a sub-10 femtosecond precision for high and low bunch charge operation. In order to fulfill the resolution demands for both modes of operation, the bandwidth of such a BAM should be increased up to a cutoff frequency of 40 GHz. In this talk, we present the design and the realization of high bandwidth cone-shaped pickup electrodes as a part of the BAM for the FEL in Hamburg (FLASH) and the European X-ray free-electron laser (European XFEL). The proposed pickup was simulated with CST STUDIO SUITE, and a non-hermetic model was built up for radio frequency (rf) measurements.

  16. Direct observation of bunching of elementary steps on protein crystals under forced flow conditions

    Directory of Open Access Journals (Sweden)

    Gen Sazaki

    2015-07-01

    Full Text Available Bunching of elementary steps by solution flow is still not yet clarified for protein crystals. Hence, in this study, we observed elementary steps on crystal surfaces of model protein hen egg-white lysozyme (HEWL under forced flow conditions, by our advanced optical microscopy. We found that in the case of a HEWL solution of 99.99% purity, forced flow changed bunched steps into elementary ones (debunching on tetragonal HEWL crystals. In contrast, in the case of a HEWL solution of 98.5% purity, forced flow significantly induced bunching of elementary steps. These results indicate that in the case of HEWL crystals, the mass transfer of impurities is more significantly enhanced by forced solution flow than that of solute HEWL molecules. We also showed that forced flow induced the incorporation of microcrystals into a mother crystal and the subsequent formation of screw dislocations and spiral growth hillocks.

  17. Bunch shape measurements at the INR linac

    International Nuclear Information System (INIS)

    The bunch shape analyser (BSA) has been developed in the INR and is used for the INR linac tuning. The operation of the device is based on a transverse scanning of a low energy secondary electrons emitted from a thin target crossed by an accelerated beam. The phase resolution obtained is better than 1deg (f = 198.2 MHz). The results of the bunch shape measurements at the exit of the first (20 MeV) accelerating cavity as well as at the exit of the drift tube linac part (100 MeV) of the accelerator are presented. The methods and the results of rf amplitudes and phases setting and a longitudinal emittance measurements with the help of BSA are described. (author)

  18. Single-bunch beams for BC-75

    International Nuclear Information System (INIS)

    On June 8, 1983, a beam consisting of a single S-band bunch was transported through the linac into the beam switchyard (BSY) and analyzed in the C-line (Beamline 27) at 30 GeV. The C-line toroid 2712 measured an intensity of approximately 2 x 109e-/pulse. The exact intensity was uncertain due to the limited response time of the toroid for fast, single-bunch beams. However, the linear Q intensity monitors (Lin Q) showed the transmission of the beam through the linac between Sectors 2 and 30 to be fairly flat with an intensity of 3 x 109e-/pulse in the final 19 sectors. The CID Faraday cup, which is located adjacent to the Gun Lin Q, was used to check the calibration of the Lin Q

  19. Production and Characterization of Attosecond Bunch Trains

    Energy Technology Data Exchange (ETDEWEB)

    Sears, Christopher M.S.; Colby, Eric; Ischebeck, Rasmus; McGuinness , Christopher; Nelson, Janice; Noble, Robert; Siemann, Robert H.; Spencer, James; Walz, Dieter; /SLAC; Plettner, Tomas; Byer, Robert L.; /Stanford U.

    2008-06-02

    We report the production of optically spaced attosecond microbunches produced by the inverse Free Electron Laser (IFEL) process. The IFEL is driven by a Ti:sapphire laser synchronized with the electron beam. The IFEL is followed by a magnetic chicane that converts the energy modulation into the longitudinal microbunch structure. The microbunch train is characterized by observing Coherent Optical Transition Radiation (COTR) at multiple harmonics of the bunching. The experimental results are compared with 1D analytic theory showing good agreement. Estimates of the bunching factors are given and correspond to a microbunch length of 350as fwhm. The formation of stable attosecond electron pulse trains marks an important step towards direct laser acceleration.

  20. Study of electron bunching in gyroklystrons

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, M.S.; Jain, P.K., E-mail: mschauhan.rs.ece@itbhu.ac.in, E-mail: pkjain.ece@itbhu.ac.in [Center of Research in Microwave Tubes, Department of Electronics Engineering, Institute of Technology, Banaras Hindu University, Varanasi (India)

    2011-07-01

    In this paper the study of electron bunching in the output cavity of gyroklystron has been carried out to optimize the output efficiency of gyroklystron by numerically solving the coupled equations obtained from nonlinear analysis, describing the strong interaction between the beam and RF fields in the output cavity of the gyroklystron. The generalized results obtained here can be applied to optimize the output efficiency of a gyroklystron of any frequency and power. (author)

  1. THE CHAOTIC BEHAVIOR OF THE BUNCHED BEAM

    International Nuclear Information System (INIS)

    Using the self consistent Vlasov equation we discuss a wave dynamical system to describe the chaotic behavior of the bunched beam, present some results of the existence of the global solutions as the generalized functions. Disappearance of the first integral, and appearance of the wave packet chaos due to birth of the continuous spectrum in Vlasov system is studied. We propose a new concept of wave packet chaos to describe the chaotic behavior of the wave dynamical system

  2. Laser-cooled bunched ion beam

    Energy Technology Data Exchange (ETDEWEB)

    Schiffer, J.P.; Hangst, J.S.; Nielsen, J.S. [and others

    1995-08-01

    In collaboration with the Arhus group, the laser cooling of a beam bunched by an rf electrode was investigated at the ASTRID storage ring. A single laser is used for unidirectional cooling, since the longitudinal velocity of the beam will undergo {open_quotes}synchrotron oscillations{close_quotes} and the ions are trapped in velocity space. As the cooling proceeds the velocity spread of the beam, as well as the bunch length is measured. The bunch length decreases to the point where it is limited only by the Coulomb repulsion between ions. The measured length is slightly (20-30%) smaller than the calculated limit for a cold beam. This may be the accuracy of the measurement, or may indicate that the beam still has a large transverse temperature so that the longitudinal repulsion is less than would be expected from an absolutely cold beam. Simulations suggest that the coupling between transverse and longitudinal degrees of freedom is strong -- but this issue will have to be resolved by further measurements.

  3. Longitudinal study of group a bunch of electrons in a linear accelerator

    International Nuclear Information System (INIS)

    For an effective use of the electron beam, the energy dispersion shall have to be the weakest possible on the other hand the beam intensity owes shall be the biggest possible. In the practice these parameters depended of the bunching elements in the accelerator. The first part of our work presents studies concerning the influence of the modulation tension in the cavity and the drift space length on the bunching quality. The second part of this study is related to development an algorithm dedicated to determine the RF and geometrical parameters which influence the bunching quality. The studied case is a cavity followed by a drift space. The result obtained by application this algorithm is in good agreement with the others simulations result.

  4. Plasma irregularities caused by cycloid bunching of the CRRES G-2 barium release

    Science.gov (United States)

    Bernhardt, P. A.; Huba, J. D.; Pongratz, M. B.; Simons, D. J.; Wolcott, J. H.

    1993-01-01

    The Combined Release and Radiation Effects Satellite (CRRES) spacecraft carried a number of barium thermite canisters for release into the upper atmosphere. The barium release labeled G-2 showed evidence of curved irregularities not aligned with the ambient magnetic field B. The newly discovered curved structures can be explained by a process called cycloid bunching. Cycloid bunching occurs when plasma is created by photoionization of a neutral cloud injected at high velocity perpendicular to B. If the injection velocity is much larger than the expansion speed of the cloud, the ion trail will form a cycloid that has irregularities spaced by the product of the perpendicular injection speed and the ion gyroperiod, Images of the solar-illuminated barium ions are compared with the results of a three-dimensional kinetic simulation. Cycloid bunching is shown to be responsible for the rapid generation of both curved and field-aligned irregularities in the CRRES G-2 experiment.

  5. Bunch length measurements using electro-optical sampling at the SLS linac

    Energy Technology Data Exchange (ETDEWEB)

    Winter, A.

    2004-07-01

    A mode-locked titanium-sapphire laser with 15 fs pulse width is used to determine the time profile of the picosecond electron bunches in the Swiss light source linac of the Paul Scherrer Institute, Villigen Switzerland. This was done using the electro-optic effect in Zinc-Telluride crystals and sampling the change induced by coherent transition radiation with the TiSa laser. The development, implementation and results of an analogue synchronisation system to synchronise the repetition rate of the TiSa laser to the radio frequency of the accelerator with a short term stability of 40 fs is presented. The experimental setup of the bunch length measurements is described and results are presented on the coincidence measurements between the laser pulses and the coherent transition radiation pulses generated by the electron bunches. (orig.)

  6. Issues for a multi-bunch operation with SPARC C-band cavities

    CERN Document Server

    Alesini, D; Mostacci, A; Palumbo, L; Spataro, B; Vaccarezza, C

    2012-01-01

    SPARC C-band traveling wave cavities were originally designed for the SPARC energy upgrade in the single bunch operation mode. In the context of a gamma source based on Compton backscattering and based on the SPARC C-band technology, we investigated the issues related to the use of these structures in the multi-bunch operation mode. Several beam configurations have been considered and the effects of transverse and longitudinal long range wakefields on beam dynamics have been studied. In the paper we present the results of these studies and, in particular, the issues related to transverse beam break-up that could prevent the multi-bunch operation. Possible HOM damped structures are also proposed.

  7. Asynchronous accelerator with RFQ injection for active longitudinal compression of accelerated bunches

    CERN Document Server

    Tumanyan, A R; Nikhogosyan, V C; Akopov, N Z; Guiragossian, Z G T; Martirosov, R M; Martirosyan, Yu.L.

    2000-01-01

    An asynchronous accelerator is described, in which the principle of itsoperation permits the active longitudinal bunch compression of acceleratedproton beams, to overcome the space charge limitation effects of intensebunches. It is shown that accelerated bunches from an RFQ linac can be adaptedfor Asynchronac injection for a multiple of choices in the accelerationfrequencies of the RFQ and the Asynchronac. The offered new type of acceleratorsystem is especially suitable to accelerate proton beams for up to 100MeVenergy and hundreds of mA average current.

  8. Production and Characterization of Bio-Char from the Pyrolysis of Empty Fruit Bunches

    OpenAIRE

    Mohamad A. Sukiran; Loh S. Kheang; Nasrin A. Bakar; Choo Y. May

    2011-01-01

    Problem statement: The palm oil industry generates an abundance of oil palm biomass such as the Empty Fruit Bunch (EFB), shell, frond, trunk and Palm Oil Mill Effluent (POME). For 88 million tones of Fresh Fruit Bunch (FFB) processed in 2008, the amount of oil palm biomass was more than 26 million tones. Studies about production of bio-char from oil palm biomass are still lacking in Malaysia. So, this study was aimed to: (i) determine the effect of pyrolysis temperatures on bio-char yield (ii...

  9. Bunch length and phase stability measurements at the TESLA test facility

    International Nuclear Information System (INIS)

    Electron bunch lengths and time jitters have been measured with sub-ps resolution at the TESLA Test Facility at DESY. Synchrotron radiation emitted from a dipole magnet reflects the longitudinal charge distribution of the electron bunch and can also be used as a timing reference of the radiation pulses produced by the free-electron laser. For sub-ps time resolution, dispersion effects of the spectrally broad-band synchrotron radiation have to be suppressed. The phase stability of the FEL pulses with respect to the radio-frequency master oscillator has been studied with a streak camera operating in synchroscan mode

  10. Design of bunch compressing system with suppression of coherent synchrotron radiation for ATF upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Jing, Yichao [Brookhaven National Lab. (BNL), Upton, NY (United States); Fedurin, Mikhail [Brookhaven National Lab. (BNL), Upton, NY (United States); Stratakis, Diktys [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-05-03

    One of the operation modes for Accelerator Test Facility (ATF) upgrade is to provide high peak current, high quality electron beam for users. Such operation requires a bunch compressing system with a very large compression ratio. The CSR originating from the strong compressors generally could greatly degrade the quality of the electron beam. In this paper, we present our design for the entire bunch compressing system that will limit the effect of CSR on the e-beam’s quality. We discuss and detail the performance from the start to end simulation of such a compressor for ATF.

  11. Excitation of Intra-bunch Vertical Motion in the SPS - Implications for Feedback Control of Ecloud and TMCI Instabilities

    CERN Document Server

    Cesaratto, John; Pivi, M T; Rivetta, C H; Turgut, O; Uemura, S; Hofle, W; Wehrle, U

    2012-01-01

    Electron cloud (ecloud) and transverse mode coupledbunch instabilities (TMCI) limit the bunch intensity in the CERN SPS. This paper presents experimental measurements in the SPS of single-bunch motion driven by a GHz bandwidth vertical excitation system [1]. The nal goal is to quantify the change in internal bunch dynamics as instability thresholds are approached, and quantify the frequencies of internal modes as ecloud effects become signicant. Initially, we have been able to drive the beam and view its motion. We show the excitation of barycentric, head-tail and higher vertical modes at different bunch intensities. The beam motion is analyzed in the time domain, via animated presentations of the sampled vertical signals, and in the frequency domain, via spectrograms showing the modal frequencies vs. time. The demonstration of the excitation of selected internal modes is a signicant step in the development of the feedback control techniques.

  12. Collective instability of bunches due to uncaptured ions

    International Nuclear Information System (INIS)

    Ionization of the residual gas by the beam may result in numerous limitations on the operational performance of storage rings. The most dangerous are the resonant phenomena, which occur when produced ions are captured in the beam due to its space charge fields. Relevant instabilities may take place in the electron, or antiproton beam. If such a beam is bunched, the ions can be captured in the beam only in the case, when their oscillations in the beam field are stable. Over-focusing of the ions due to either a proper choice of the bunch intensity and the bunch to bunch distance, or missing of some amount of bunches providing an empty gap in the beam can help to pump ions out of the closed orbit and to eliminate these limitations. However, even in the case, when the ion oscillations in the beam are unstable, the ions leave the closed orbit during some finite time. Provided that this time is longer than the bunch to bunch period, the ions couple coherent oscillations of the beam bunches making those unstable. In particular, such an instability may take place both in the negatively charged and in the positively charged beams (protons, positrons). The long gap in the bunch train essentiality changes the nature of the instability, if the ions produced by last bunches are removed from the closed orbit prior to perturb the oscillations of the first bunch. Without such a feedback the instability becomes the beam break-up type with essentially non-exponential growth of the amplitudes of oscillations. It is important that any exponential decay will finally damp these unstable oscillations. In this report we present simplified calculations related to the collective multi-bunch instability due to uncaptured ions in positron, or electron bunches taking into account the gap in the beam. In the beam with a gap, the interaction of the bunches via uncaptured ions results in the beam break-up instability of the beam provided that ion is completely pumped out by the gap. This

  13. On measuring charged particle bunch duration in linear accelerators

    International Nuclear Information System (INIS)

    The process of measuring short bunches is simulated by means of cavity resonators in which HF fields are excited by both positive and negative ion bunches flying through them. The simulation is aimed to assess optimum operation of a linear accelerator. A set of bunches of chance form and duration is simulated. Then the simulation of the process of restoring the duration and shape of a bunch according to data obtained from a limited number of resonators is realized. The use of 3-4 resonators tuned to 3, 6, 9 and 12-th harmonics of bunch repetition rate is shown to be sufficient for determining bunch duration with an accuracy of several per cent. When data on harmonic phases is available, one can obtain information on beam asymmetry

  14. Spatio-temporal dynamics of relativistic electron bunches during the micro bunching instability: study of the Synchrotron Soleil and UVSOR storage rings

    International Nuclear Information System (INIS)

    Relativistic electron bunches circulating in storage rings are used to produce intense radiation from far-infrared to X-rays. However, above a density threshold value, the interaction between the electron bunch and its own radiation can lead to a spatio-temporal instability called micro bunching instability. This instability is characterized by a strong emission of coherent THz radiation (typically 105 times stronger than the classical synchrotron radiation) which is a signature of the presence of microstructures (at mm scale) in the electron bunch. This instability is known to be a fundamental limitation of the operation of synchrotron light sources at high beam current. In this thesis, we have focused on this instability from a nonlinear dynamics point of view by combining experimental studies carried out at the Synchrotron Soleil and UVSOR storage rings with numerical studies mainly based on the Vlasov-Fokker-Planck equation. In a first step, due to the very indirect nature of the experimental observations, we have sought to deduce information on the microstructure wavenumber either by looking at the temporal evolution of the THz signal emitted during the instability or by studying the response of the electron bunch to a laser perturbation. In a second step, we have achieved direct, real time observations of the microstructures dynamics through two new, very different, detection techniques: a thin-film superconductor-based detector at UVSOR, and a spectrally-encoded electro-optic detection technique at Soleil. These new available experimental observations have allowed severe comparisons with the theoretical models. (author)

  15. Beam manipulation with velocity bunching for PWFA applications

    Science.gov (United States)

    Pompili, R.; Anania, M. P.; Bellaveglia, M.; Biagioni, A.; Bisesto, F.; Chiadroni, E.; Cianchi, A.; Croia, M.; Curcio, A.; Di Giovenale, D.; Ferrario, M.; Filippi, F.; Galletti, M.; Gallo, A.; Giribono, A.; Li, W.; Marocchino, A.; Mostacci, A.; Petrarca, M.; Petrillo, V.; Di Pirro, G.; Romeo, S.; Rossi, A. R.; Scifo, J.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Zhu, J.

    2016-09-01

    The activity of the SPARC_LAB test-facility (LNF-INFN, Frascati) is currently focused on the development of new plasma-based accelerators. Particle accelerators are used in many fields of science, with applications ranging from particle physics research to advanced radiation sources (e.g. FEL). The demand to accelerate particles to higher and higher energies is currently limited by the effective efficiency in the acceleration process that requires the development of km-size facilities. By increasing the accelerating gradient, the compactness can be improved and costs reduced. Recently, the new technique which attracts main efforts relies on plasma acceleration. In the following, the current status of plasma-based activities at SPARC_LAB is presented. Both laser- and beam-driven schemes will be adopted with the aim to provide an adequate accelerating gradient (1-10 GV/m) while preserving the brightness of the accelerated beams to the level of conventional photo-injectors. This aspect, in particular, requires the use of ultra-short (< 100 fs) electron beams, consisting in one or more bunches. We show, with the support of simulations and experimental results, that such beams can be produced using RF compression by velocity-bunching.

  16. Bunch Extension Monitor for LINAC of SPIRAL2 facility

    OpenAIRE

    Revenko, R.V.; Vignet, J.-L.

    2013-01-01

    Measurements of the bunch longitudinal shape of beam particles are crucial for optimization and control of the LINAC beam parameters and maximization of its integrated luminosity. The non-interceptive bunch extension monitor for LINAC of SPIRAL2 facility is being developed at GANIL. The five bunch extension monitors are to be installed on the entrance of LINAC between superconducting cavities. The principle of monitor operation is based on registration of x-rays induced by ions of accelerator...

  17. Modeling Hofmeister Effects.

    Science.gov (United States)

    Hribar-Lee, Barbara; Vlachy, Vojko; Dill, Ken A

    2009-03-11

    A two dimensional model of water, so-called Mercedes-Benz model, was used to study effects of the size of hydrophobic solute on the insertion thermodynamics in electrolyte solutions. The model was examined by the constant pressure Monte Carlo computer simulation. The results were compared with the experimental data for noble gasses and methane in water and electrolyte solution. The influence of different ions at infinite dilution on the free energy of transfer was explored. Qualitative agreement with the experimental results was obtained. The mechanism of Hofmeister effects was proposed. PMID:20161468

  18. Optical Synchronization and Electron Bunch Diagnostic at ELBE

    OpenAIRE

    Bousonville, Michael; Czwalinna, M. K.; Schlarb, H.; Schulz, S.; Vilcins, S.; Kuntzsch, Michael; Gensch, Michael; Lehnert, U.; Röser, F.; Schurig, R

    2013-01-01

    The continuous wave electron accelerator ELBE is upgraded to generate short and highly charged electron bunches (~200fs duration, up to 1 nC) . In the last years a prototype of an optical synchronization system using a mode locked fiber laser has been build up at ELBE which is now in commissioning phase. The stabilized pulse train can be used for new methods of electron bunch diagnostics like bunch arrival time measurements with the potential of femtosecond resolution. At ELBE a bunch arrival...

  19. Longitudinal Bunch Lengthening Compensation in High Charge RF Photoinjector

    Energy Technology Data Exchange (ETDEWEB)

    Pei, S.; Adolphsen, C.; /SLAC

    2008-10-03

    In high charge RF photoinjectors for wakefield two beam acceleration studies, due to the strong longitudinal space charge, bunch lengthening between the photocathode and photoinjector exit is a critical issue. We present beam dynamics studies of bunch lengthening in an RF photoinjector for a high charge electron beam and describe methods to compensate the bunch lengthening to various degrees. In particular, the beam dynamics for bunch charge from 1nC to 30nC are studied for an S-band 2856 MHz photoinjector.

  20. Tax Bunching, Income Shifting and Self-employment

    DEFF Research Database (Denmark)

    le Maire, Christian Daniel; Schjerning, Bertel

    This paper proposes a dynamic extension to Saez (2010) bunching formula that allows us to distinguish bunching based on real responses and income shifting. We provide direct evidence of income shifting and pronounced bunching in taxable income for the case of Danish self-employed. If income...... shifting was neglected in this case, we would conclude that taxable incomes were highly sensitive to changes in marginal tax rates. We show, however, that more than half of the observed bunching in taxable income for the self-employed is driven by intertemporal income shifting, implying a structural...

  1. Tax Bunching, Income Shifting and Self-employment

    DEFF Research Database (Denmark)

    le Maire, Christian Daniel; Schjerning, Bertel

    2013-01-01

    This paper proposes a dynamic extension to Saez (2010) bunching formula that allows us to distinguish bunching based on real responses and income shifting. We provide direct evidence of income shifting and pronounced bunching in taxable income for the Danish self-employed. If income shifting was...... neglected in this case, we would estimate a taxable income elasticity in the range of 0.43-0.53 and conclude that taxable incomes were highly sensitive to changes in marginal tax rates. We show, however, that more than half of the bunching in taxable income is driven by intertemporal income shifting...

  2. Observations involving broadband impedance modelling

    Energy Technology Data Exchange (ETDEWEB)

    Berg, J.S. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1996-08-01

    Results for single- and multi-bunch instabilities can be significantly affected by the precise model that is used for the broadband impedance. This paper discusses three aspects of broadband impedance modelling. The first is an observation of the effect that a seemingly minor change in an impedance model has on the single-bunch mode coupling threshold. The second is a successful attempt to construct a model for the high-frequency tails of an r.f. cavity. The last is a discussion of requirements for the mathematical form of an impedance which follow from the general properties of impedances. (author)

  3. Shielded transient self-interaction of a bunch entering a circle from a straight path

    International Nuclear Information System (INIS)

    Recent developments in electron-gun and injector technologies enable production of short (mm-length), high-charge (nC-regime) bunches. In this parameter regime, the curvature effect on the bunch self-interaction, by way of coherent synchrotron radiation (CSR) and space-charge forces as the beam traverses magnet bends, may cause serious emittance degradation. In this paper, the authors study an electron bunch orbiting between two infinite, parallel conducting plates. The bunch moves on a trajectory from a straight path to a circular orbit and begins radiating. Transient effects, arising from CSR and space-charge forces generated from source particles both on the bend and on the straight path prior to the bend, are analyzed using Lienard-Wiechert fields, and their overall net effect is obtained. The influence of the plates on the transients is contrasted to their shielding of the steady-state radiated power. Results for emittance degradation induced by this self-interaction are also presented

  4. Face Recognition by Extending Elastic Bunch Graph Matching with Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    Rajinda Senaratne

    2009-08-01

    Full Text Available Elastic Bunch Graph Matching is one of the well known methods proposed for face recognition. In this work, we propose several extensions to Elastic Bunch Graph Matching and its recent variant Landmark Model Matching. We used data from the FERET database for experimentations and to compare the proposed methods. We apply Particle Swarm Optimization to improve the face graph matching procedure in Elastic Bunch Graph Matching method and demonstrate its usefulness. Landmark Model Matching depends solely on Gabor wavelets for feature extraction to locate the landmarks (facial feature points. We show that improvements can be made by combining gray-level profiles with Gabor wavelet features for feature extraction. Furthermore, we achieve improved recognition rates by hybridizing Gabor wavelet with eigenface features found by Principal Component Analysis, which would provide information contained in the overall appearance of a face. We use Particle Swarm Optimization to fine tune the hybridization weights. Results of both fully automatic and partially automatic versions of all methods are presented. The best-performing method improves the recognition rate up to 22.6% and speeds up the processing time by 8 times over the Elastic Bunch Graph Matching for the fully automatic case.

  5. Beam transport and bunch compression at TARLA

    Energy Technology Data Exchange (ETDEWEB)

    Aksoy, Avni, E-mail: avniaksoy@ankara.edu.tr [Ankara University, Ankara (Turkey); Lehnert, Ulf [HZDR, Dresden (Germany)

    2014-10-21

    The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) will operate two InfraRed Free Electron Lasers (IR-FEL) covering the range of 3–250 μm. The facility will consist of an injector fed by a thermionic triode gun with two-stage RF bunch compression, two superconducting accelerating ELBE modules operating at continuous wave (CW) mode and two independent optical resonator systems with different undulator period lengths. The electron beam will also be used to generate Bremsstrahlung radiation. In this study, we present the electron beam transport including beam matching to the undulators and the shaping of the longitudinal phase space using magnetic dispersive sections.

  6. Beam transport and bunch compression at TARLA

    International Nuclear Information System (INIS)

    The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) will operate two InfraRed Free Electron Lasers (IR-FEL) covering the range of 3–250 μm. The facility will consist of an injector fed by a thermionic triode gun with two-stage RF bunch compression, two superconducting accelerating ELBE modules operating at continuous wave (CW) mode and two independent optical resonator systems with different undulator period lengths. The electron beam will also be used to generate Bremsstrahlung radiation. In this study, we present the electron beam transport including beam matching to the undulators and the shaping of the longitudinal phase space using magnetic dispersive sections

  7. Silica aerogel radiators for bunch length measurements

    International Nuclear Information System (INIS)

    Cherenkov radiators based on silica aerogel are used to measure the electron bunch length at the photo injector test facility at DESY Zeuthen (PITZ). The energy range of those electrons is 4-5 MeV. In this paper, the time resolution defined by the usage of aerogel is calculated analytically and Monte Carlo simulations are performed. It is shown that silica aerogel gives the possibility to reach a time resolution of about 0.1 ps for high photon intensities and a time resolution of about 0.02 ps can be obtained for thin silica aerogel radiators

  8. Studies of transverse coherent bunch instabilities for the Advanced Light Source (ALS)

    International Nuclear Information System (INIS)

    We have studied the transverse coherent bunch instabilities for the Advanced Light Source (ALS). We have in particular applied a Hamiltonian formalism to obtain the linearized averaged equations of motion (i.e. the one turn map) for the resistive wall effect to obtain the corresponding localized kick when the beta function is varying along the lattice. We have also included a 2-dimensional model for the transverse higher order cavity modes. In addition, we have used power series maps to represent the lattice which enabled us to include non-linear effects. These models have been implemented in a computer code and numerical simulations have been carried out for ALS. The model was successfully verified against analytical calculations in cases where they overlap. The non-linear effects from the lattice proved to be important, since they led to a qualitative change of the dynamics for the stored beam. We also studied the injection process in some detail and found that the non-linear effects also fundamentally change the injection dynamics

  9. Status of digital bunch-by-bunch feedback systems at DELTA and their application as diagnostics tools

    International Nuclear Information System (INIS)

    Digital bunch-by-bunch feedback systems allow to detect and counteract longitudinal as well as transverse multi-bunch instabilities. Beam current-dependent grow-damp measurements have been performed in order to characterize these instabilities at the DELTA storage ring. The longitudinal feedback system is used permanently during the operation of the new short-pulse facility in order to damp longitudinal bunch oscillations. Besides that, all three feedback systems are in use as excellent diagnostics tools, e.g. to investigate the injection process or to take data during sudden beam loss for post-processing.

  10. Electron bunches are cut down to size

    International Nuclear Information System (INIS)

    Physicists have used ultrashort pulses of light to control the motion of electrons ejected from molecules and to produce electron beams just a few nanometres in length. One of the unwritten laws of physics seems to be that ever-larger experiments are needed to observe ever-smaller objects. Bigger and bigger accelerators have been built to probe the structure of molecules, atoms, nuclei and sub-nuclear particles. Recently, however, this trend has started to reverse: tabletop accelerators and particle storage rings the size of saucers are beginning to appear in the laboratory, while atoms can be trapped on a microchip. Now we may be witnessing yet another radical reduction in size following the construction of an electron beam that measures just a few atoms across. Recently Paul Corkum and co-workers at the National Research Council (NRC) of Canada in Ottawa and the University of Sherbrooke, also in Canada, have managed to generate and manipulate bunches of electrons that extend for less than a nanometre - i.e. less than about 10 atomic diameters - in all three dimensions. The bunches are also extremely short-lived and last for just a few hundred attoseconds (10-18 s), not much longer than it would take an electron to orbit around the nucleus (H Niikura et al. 2002 Nature 417 917). In the September issue of Physics World, Armin Scrinzi of the Vienna University of Technology, Austria, describes how these 'nanobeams' are created. (U.K.)

  11. Analytical Formulas for Short Bunch Wakes in a Flat Dechirper

    CERN Document Server

    Bane, K; Zagorodnov, I

    2016-01-01

    We develop analytical models of the longitudinal and transverse wakes, on and off axis for realistic structures, and then compare them with numerical calculations, and generally find good agreement. These analytical "first order" formulas approximate the droop at the origin of the longitudinal wake and of the slope of the transverse wakes; they represent an improvement in accuracy over earlier, "zeroth order" formulas. In example calculations for the RadiaBeam/LCLS dechirper using typical parameters, we find a 16\\% droop in the energy chirp at the bunch tail compared to simpler calculations. With the beam moved to 200~$\\mu$m from one jaw in one dechiper section, one can achieve a 3~MV transverse kick differential over a 30~$\\mu$m length.

  12. Analytical Formulas for Short Bunch Wakes in a Flat Dechirper

    Energy Technology Data Exchange (ETDEWEB)

    Bane, Karl [SLAC National Accelerator Lab., Menlo Park, CA (United States); Stupakov, Gennady [SLAC National Accelerator Lab., Menlo Park, CA (United States); Zagorodnov, Igor [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2016-03-29

    We develop analytical models of the longitudinal and transverse wakes, on and off axis for realistic structures, and then compare them with numerical calculations, and generally find good agreement. These analytical "first order" formulas approximate the droop at the origin of the longitudinal wake and of the slope of the transverse wakes; they represent an improvement in accuracy over earlier, "zeroth order" formulas. In example calculations for the RadiaBeam/LCLS dechirper using typical parameters, we find a 16% droop in the energy chirp at the bunch tail compared to simpler calculations. With the beam moved to 200 m from one jaw in one dechiper section, one can achieve a 3 MV transverse kick differential over a 30 m length.

  13. Analytical formulas for short bunch wakes in a flat dechirper

    Science.gov (United States)

    Bane, Karl; Stupakov, Gennady; Zagorodnov, Igor

    2016-08-01

    We develop analytical models of the longitudinal and transverse wakes, on and off axis for a flat, corrugated beam pipe with realistic parameters, and then compare them with numerical calculations, and generally find good agreement. These analytical "first order" formulas approximate the droop at the origin of the longitudinal wake and of the slope of the transverse wakes; they represent an improvement in accuracy over earlier, "zeroth order" formulas. In example calculations for the RadiaBeam/LCLS dechirper using typical parameters, we find a 16% droop in the energy chirp at the bunch tail compared to simpler calculations. With the beam moved to 200 μ m from one jaw in one dechirper section, one can achieve a 3 MV transverse kick differential over a 30 μ m length.

  14. Analytical Formulas for Short Bunch Wakes in a Flat Dechirper

    International Nuclear Information System (INIS)

    We develop analytical models of the longitudinal and transverse wakes, on and off axis for realistic structures, and then compare them with numerical calculations, and generally find good agreement. These analytical 'first order' formulas approximate the droop at the origin of the longitudinal wake and of the slope of the transverse wakes; they represent an improvement in accuracy over earlier, 'zeroth order' formulas. In example calculations for the RadiaBeam/LCLS dechirper using typical parameters, we find a 16% droop in the energy chirp at the bunch tail compared to simpler calculations. With the beam moved to 200 m from one jaw in one dechiper section, one can achieve a 3 MV transverse kick differential over a 30 m length.

  15. LHC Report: spring cleaning over, bunches of luminosity

    CERN Multimedia

    CERN Bulletin

    2011-01-01

    Scrubbing was completed on Wednesday 13 April. The run had seen over 1000 bunches per beam successfully circulating at 450 GeV. Measurements showed that electron cloud activity in the cold regions had been suppressed. A decrease of vacuum activity in the warm regions demonstrated that the cleaning had also achieved the required results there. As discussed in the last Bulletin, the scrubbing was performed with high intensity bunches with 50 nanosecond spacing. Given the potential luminosity performance with this spacing (more bunches, higher bunch intensity from the injectors) and in the light of the results of the scrubbing run, the decision was taken to continue the 2011 physics run with this bunch spacing.   A few issues with 50 nanosecond spacing had to be resolved when standard operations for luminosity production resumed. Once things had been tidied up, stable beams were provided for the experiments, firstly with 228 bunches per beam and then with 336 bunches per beam. The 336 bunch fill that w...

  16. Coupled-Beam and Coupled-Bunch Instabilities

    CERN Document Server

    Burov, Alexey

    2016-01-01

    A problem of coupled-beam instability is solved for two multibunch beams with slightly different revolution frequencies, as in the Fermilab Recycler Ring (RR). Sharing of the inter-bunch growth rates between the intra-bunch modes is described. The general analysis is applied to the RR; possibilities to stabilize the beams by means of chromaticity, feedback and Landau damping are considered.

  17. AN ONLINE LONGITUDINAL VERTEX AND BUNCH SPECTRUM MONITOR FOR RHIC

    International Nuclear Information System (INIS)

    The longitudinal bunch profile acquisition system at RHIC was recently upgraded to allow on-line measurements of the bunch spectrum, and collision vertex location and shape. The system allows monitoring the evolution of these properties along the ramp, at transition and rebucketing, and at store conditions. We describe some of the hardware and software changes, and show some applications of the system

  18. Electron bunch length measurement at the Vanderbilt FEL

    Energy Technology Data Exchange (ETDEWEB)

    Amirmadhi, F.; Brau, C.A.; Mendenhall, M. [Vanderbilt Free-Electron-Laser Center, Nashville, TN (United States)] [and others

    1995-12-31

    During the past few years, a number of experiments have been performed to demonstrate the possibility to extract the longitudinal charge distribution from spectroscopic measurements of the coherent far-infrared radiation emitted as transition radiation or synchrotron radiation. Coherent emission occurs in a spectral region where the wavelength is comparable to or longer than the bunch length, leading to an enhancement of the radiation intensity that is on the order of the number of particles per bunch, as compared to incoherent radiation. This technique is particularly useful in the region of mm and sub-mm bunch lengths, a range where streak-cameras cannot be used for beam diagnostics due to their limited time resolution. Here we report on experiments that go beyond the proof of principle of this technique by applying it to the study and optimization of FEL performance. We investigated the longitudinal bunch length of the Vanderbilt FEL by analyzing the spectrum of coherent transition radiation emitted by the electron bunches. By monitoring the bunch length while applying a bunch-compression technique, the amount of the compression could be easily observed. This enabled us to perform a systematic study of the FEL performance, especially gain and optical pulse width, as a function of the longitudinal electron distribution in the bunch. The results of this study will be presented and discussed.

  19. Single-shot longitudinal shape measurements of nanosecond particle bunches

    International Nuclear Information System (INIS)

    Since September 1986 the CERN Proton Synchrotron (PS) machine, as part of the LEP injector chain, is able to accelerate electrons besides the various usual hadron particles. It should be noted that owing to their peculiar dynamics, electron bunches are generally much shorter than hadron bunches. Typical values for the total bunch length in the PS are: - for Gaussian electron bunches: 0.7-5 ns, - for parabolic hadron bunches: 3-100 ns. Peak current intensities range from less than 1 mA (oxygen) to more than 50 A for high-intensity proton beams, whilst electron bunches have peak currents of about 1-3 A. In order to match the RF system and to avoid instabilities at injection in the Super Proton Synchrotron (SPS), the longitudinal dimensions (energy spread and length) of the electron bunches have to be carefully adjusted in the PS to the following nominal values before extraction: σ/sub E/E = 10-3, 4σ/sub t/ = 2.1 ns. An instrument providing a precise measurement of the bunch shape is thus of primary importance. The apparatus presented here consists of a wide-band pick-up, a transient digitizer, and a small computer for control and signal handling

  20. Bunched soliton states in weakly coupled sine-Gordon systems

    DEFF Research Database (Denmark)

    Grønbech-Jensen, N.; Samuelsen, Mogens Rugholm; Lomdahl, P. S.; Blackburn, J. A.

    1990-01-01

    The interaction between solitons of two weakly coupled sine-Gordon systems is considered. In particular, the stability of bunched states is investigated, and perturbation results are compared with numerical results.......The interaction between solitons of two weakly coupled sine-Gordon systems is considered. In particular, the stability of bunched states is investigated, and perturbation results are compared with numerical results....

  1. Very Short Bunches in MIT-Bates South Hall Ring

    CERN Document Server

    Wang, Dong; Farkhondeh, Manouchehr; Franklin, Wilbur; Graves, William; Ihloff, Ernie; Podobedov, Boris; Tschalär, C; Wang, Defa; Wang, Fuhua; Zwart, Townsend; van der Laan, Jan

    2005-01-01

    The study of ultra-short bunches in MIT SHR storage ring with very small momentum compactions is carried out. The ultra-short bunches are to greatly enhence the coherent radiation by many orders of magnitude. The ring lattice is resigned to reach very small momentum compaction factor down to 1·10-5

  2. Energy Spectra from Electromagnetic Fields Generated by Ultra-relativistic Charged Bunches in a Perfectly Conducting Cylindrical Beam Pipe

    CERN Document Server

    Hale, Alison C

    2009-01-01

    The spectrum of electromagnetic fields satisfying perfectly conducting boundary conditions in a segment of a straight beam pipe with a circular cross-section is discussed as a function of various source models. These include charged bunches that move along the axis of the pipe with constant speed for which an exact solution to the initial-boundary value problem for Maxwell's equations in the beam pipe is derived. In the ultra-relativistic limit all longitudinal components of the fields tend to zero and the spectral content of the transverse fields and average total electromagnetic energy crossing any section of the beam pipe are directly related to the properties of the ultra-relativistic source. It is shown that for axially symmetric ultra-relativistic bunches interference effects occur that show a striking resemblance to those that occur due to CSR in cyclic machines despite the fact that in this limit the source is no longer accelerating. The results offer an analytic description showing how such enhanced ...

  3. Longitudinal diffusion of a proton bunch under external noise

    International Nuclear Information System (INIS)

    Evolution of longitudinal distribution of a proton bunch subjected to stationary (amplitude or phase) RF-noises is governed by a diffusion equation. Its diffusion coefficient is essentially nonlinear and, possibility, diverges near separatrix. The paper deals with the dynamical foundations of this diffusive approximation. Treated in detail is the motion of particles located either inside, or outside stationary buckets (beam halo). The formal statement of boundary-value problem for the noise-induced diffusion of a bunch (zero boundary conditions at separatrix, or at infinity) is discussed. Both these problems are solved numerically for arbitrarily long bunches. Use is made of the Finite Element Technique (spatial discretization), and of the Crank-Nicolson's scheme (time-domain integration). Computed estimates of the representative bunch life-times for the wide-band (white) noise approximation are presented. These emerge from the criteria of either bunch quality degradation, or of its population loss. 6 refs.; 11 figs

  4. Cherenkov loss factor of short relativistic bunches:general approach

    CERN Document Server

    Baturin, S S

    2013-01-01

    The interaction of short relativistic charged particle bunches with waveguides and other accelerator system components is a critical issue for the development of X-ray FELs (free electron lasers) and linear collider projects. Wakefield Cherenkov losses of short bunches have been studied previously for resistive wall, disk-loaded, corrugated and dielectric loaded waveguides. It was noted in various publications [1] that if the slowdown layer is thin, the Cherenkov loss factor of a short bunch does not depend on the guiding system material and is a constant for any given transverse cross section dimensions of the waveguides. In this paper, we consider a new approach to the analysis of loss factors for relativistic short bunches and formulate a general integral relation that allows calculation of the loss factor for a short relativistic bunch passing an arbitrary waveguide system. The loss factors calculated by this new method for various types of waveguides with arbitrary thickness slowdown layers, including in...

  5. A Proof of Principle of Asymmetric Bunch Pair Merging

    CERN Document Server

    Benedikt, Michael; Vallet, J L; CERN. Geneva. AB Department

    2003-01-01

    Bunch splitting was established as a routine operation in the arsenal of rf gymnastics in the PS Complex long before it became the saving grace of the beam for the LHC. Historically, however, it was born out of the time-reversed analogue process of merging, in which a pair of bunches are combined. Hitherto, both operations have been performed with bunches of equal longitudinal emittance. Now an asymmetric merging process has been demonstrated. By combining a bunch with a small empty bucket, it is possible to deplete only the central density of the resultant particle distribution. This would allow bunches to be tailored with quasi-flat line densities. The details of the method are presented together with some measurements.

  6. Over-compression, a method to shape the longitudinal bunch distribution for a reduced energy spread

    International Nuclear Information System (INIS)

    In the Stanford Linear Collider the energy spread of the bunches at the end of the linac is dominated by longitudinal wakefields. A short, high current bunch with a Gaussian shape will produce a double-horned energy distribution. It can be shown that certain charge distributions with a sharp rise time (about rectangular or half-Gaussian) will give no additional energy spread due to the linac, since the generated wakefield and the rf-curvature cancel each other exactly. In this paper different methods are presented on how to achieve such distributions by using non-linear dependences in the RTL (Ring-To-Linac) compression region. A simple and effective method to achieve such a distribution is by over-compression. When not fully compressing the bunch, there are two settings of the compressor voltage, under and over-compression, which give the same core bunch length in the linac. By switching from the under to the over-compressed setting, the tails are reduced from more than Gaussian to less than Gaussian beam tails. This results in a roughly rectangular shape which will give the wakefield-rf cancellation. Simulations, measurements and their implications are discussed

  7. Parallel Beam-Beam Simulation Incorporating Multiple Bunches and Multiple Interaction Regions

    CERN Document Server

    Jones, F W; Pieloni, T

    2007-01-01

    The simulation code COMBI has been developed to enable the study of coherent beam-beam effects in the full collision scenario of the LHC, with multiple bunches interacting at multiple crossing points over many turns. The program structure and input are conceived in a general way which allows arbitrary numbers and placements of bunches and interaction points (IP's), together with procedural options for head-on and parasitic collisions (in the strong-strong sense), beam transport, statistics gathering, harmonic analysis, and periodic output of simulation data. The scale of this problem, once we go beyond the simplest case of a pair of bunches interacting once per turn, quickly escalates into the parallel computing arena, and herein we will describe the construction of an MPI-based version of COMBI able to utilize arbitrary numbers of processors to support efficient calculation of multi-bunch multi-IP interactions and transport. Implementing the parallel version did not require extensive disruption of the basic ...

  8. Bunch mode specific rate corrections for PILATUS3 detectors

    Energy Technology Data Exchange (ETDEWEB)

    Trueb, P., E-mail: peter.trueb@dectris.com [DECTRIS Ltd, 5400 Baden (Switzerland); Dejoie, C. [ETH Zurich, 8093 Zurich (Switzerland); Kobas, M. [DECTRIS Ltd, 5400 Baden (Switzerland); Pattison, P. [EPF Lausanne, 1015 Lausanne (Switzerland); Peake, D. J. [School of Physics, The University of Melbourne, Victoria 3010 (Australia); Radicci, V. [DECTRIS Ltd, 5400 Baden (Switzerland); Sobott, B. A. [School of Physics, The University of Melbourne, Victoria 3010 (Australia); Walko, D. A. [Argonne National Laboratory, Argonne, IL 60439 (United States); Broennimann, C. [DECTRIS Ltd, 5400 Baden (Switzerland)

    2015-04-09

    The count rate behaviour of PILATUS3 detectors has been characterized for seven bunch modes at four different synchrotrons. The instant retrigger technology of the PILATUS3 application-specific integrated circuit is found to reduce the dependency of the required rate correction on the synchrotron bunch mode. The improvement of using bunch mode specific rate corrections based on a Monte Carlo simulation is quantified. PILATUS X-ray detectors are in operation at many synchrotron beamlines around the world. This article reports on the characterization of the new PILATUS3 detector generation at high count rates. As for all counting detectors, the measured intensities have to be corrected for the dead-time of the counting mechanism at high photon fluxes. The large number of different bunch modes at these synchrotrons as well as the wide range of detector settings presents a challenge for providing accurate corrections. To avoid the intricate measurement of the count rate behaviour for every bunch mode, a Monte Carlo simulation of the counting mechanism has been implemented, which is able to predict the corrections for arbitrary bunch modes and a wide range of detector settings. This article compares the simulated results with experimental data acquired at different synchrotrons. It is found that the usage of bunch mode specific corrections based on this simulation improves the accuracy of the measured intensities by up to 40% for high photon rates and highly structured bunch modes. For less structured bunch modes, the instant retrigger technology of PILATUS3 detectors substantially reduces the dependency of the rate correction on the bunch mode. The acquired data also demonstrate that the instant retrigger technology allows for data acquisition up to 15 million photons per second per pixel.

  9. Bunch mode specific rate corrections for PILATUS3 detectors

    International Nuclear Information System (INIS)

    The count rate behaviour of PILATUS3 detectors has been characterized for seven bunch modes at four different synchrotrons. The instant retrigger technology of the PILATUS3 application-specific integrated circuit is found to reduce the dependency of the required rate correction on the synchrotron bunch mode. The improvement of using bunch mode specific rate corrections based on a Monte Carlo simulation is quantified. PILATUS X-ray detectors are in operation at many synchrotron beamlines around the world. This article reports on the characterization of the new PILATUS3 detector generation at high count rates. As for all counting detectors, the measured intensities have to be corrected for the dead-time of the counting mechanism at high photon fluxes. The large number of different bunch modes at these synchrotrons as well as the wide range of detector settings presents a challenge for providing accurate corrections. To avoid the intricate measurement of the count rate behaviour for every bunch mode, a Monte Carlo simulation of the counting mechanism has been implemented, which is able to predict the corrections for arbitrary bunch modes and a wide range of detector settings. This article compares the simulated results with experimental data acquired at different synchrotrons. It is found that the usage of bunch mode specific corrections based on this simulation improves the accuracy of the measured intensities by up to 40% for high photon rates and highly structured bunch modes. For less structured bunch modes, the instant retrigger technology of PILATUS3 detectors substantially reduces the dependency of the rate correction on the bunch mode. The acquired data also demonstrate that the instant retrigger technology allows for data acquisition up to 15 million photons per second per pixel

  10. Simulations of the ILC Electron Gun and Electron Bunching System

    International Nuclear Information System (INIS)

    The International Linear Collider (ILC) is a proposed electron-positron collider, expected to provide insight into important questions in particle physics. A part of the global R and D effort for the ILC is the design of its electron gun and electron bunching system. The present design of the bunching system has two sub-harmonic bunchers, one operating at 108 MHz and one at 433MHz, and two 5-cell 1.3 GHz (L-band) bunchers. This bunching system has previously been simulated using the Phase and Radial Motion in Electron Linear Accelerators (PARMELA) software, and those simulations indicated that the design provides sufficient bunching and acceleration. Due to the complicated dynamics governing the electrons in the bunching system we decided to verify and expand the PARMELA results using the more recent and independent simulation software General Particle Tracer (GPT). GPT tracks the motion and interactions of a set of macro particles, each of which represent a number of electrons, and provides a variety of analysis capabilities. To provide initial conditions for the macro particles, a method was developed for deriving the initial conditions from detailed simulations of particle trajectories in the electron gun. These simulations were performed using the Egun software. For realistic simulation of the L-band bunching cavities, their electric and magnetic fields were calculated using the Superfish software and imported into GPT. The GPT simulations arrived at similar results to the PARMELA simulations for sub-harmonic bunching. However, using GPT it was impossible to achieve an efficient bunching performance of the first L-band bunching cavity. To correct this, the first L-band buncher cell was decoupled from the remaining 4 cells and driven as an independent cavity. Using this modification we attained results similar to the PARMELA simulations. Although the modified bunching system design performed as required, the modifications are technically challenging to implement

  11. Extreme short electron bunch generation based on velocity bunching in accelerating structure at t-ACTS, Tohoku University

    International Nuclear Information System (INIS)

    We are conducting a beam experiment of sub-picosecond electron bunch generation at t-ACTS (test accelerator as a coherent terahertz source), Tohoku University. In the t-ACTS, the intense coherent terahertz radiation will be generated from an undulator and an isochronous accumulator ring via producing sub-picosecond bunches. The accelerator is composed of a thermionic cathode rf gun, an alpha magnet and a 3 m-long accelerating structure. Velocity bunching scheme in accelerating structure is applied to generate the short electron bunch. The thermionic rf gun consists of two independent cavities has been developed, which is capable of manipulating the beam longitudinal phase space. To produced femtosecond electron bunch, the longitudinal phase space distribution of the beam entering the accelerating structure is optimized by changing the rf gun parameters. The bunch length is measured by observing an optical tradition radiation using a streak camera. In the study of femtosecond electron bunch generation, a relation between the rf gun parameters and the bunch length after compression was investigated. The preliminary results of experiments are described in this report. (author)

  12. Multi-bunch energy spread induced by beam loading in standing wave structure

    International Nuclear Information System (INIS)

    The interaction of a relativistic beam with the modes of the TM010 pass-band of a multicell cavity does not cause any problem: although all the modes are excited by the RF (radiofrequency) generator, resulting in different cell excitations during the cavity filling and the beam pulse, the net accelerating field exhibits negligible fluctuations from bunch to bunch. However, when the beam is not fully relativistic, this is no more true. The phase slippage occurring in the first cells, between the non relativistic beam and the lower pass-band modes, produces an effective enhancement of the shunt impedances, which is usually negligible for a relativistic beam in a well tuned cavity. Moreover, the voltage jumps (amplitude and phase) occurring at each bunch passage, as well as the beam detuning caused by the off-crest bunches, vary from cell to cell. These effects enhance dramatically the fluctuation of the accelerating voltage, with a dominant beating provided by the pass-band mode nearest to the pi-mode. The induced beam energy spread has been estimated by the help of two distinct codes, developed at Frascati (Italy) and (Saclay), with results in good agreement. While an interaction integral is computed at each bunch passage, the cavity refilling is calculated by solving coupled differential equations of the modes of the pass-band, driven by a generator linked to one end-cell. It is shown also that the intermode coupling arises from the external Q of the drive end-cell, and not from the wall losses. For illustration, the authors applied the method to the beam-loading problem in the SC capture cavity of the low charge injector of the TESLA test facility installed at DESY

  13. Much Ado about Microbunching: Coherent Bunching in High Brightness Electron Beams

    Energy Technology Data Exchange (ETDEWEB)

    Ratner, Daniel [Stanford Univ., CA (United States)

    2011-05-01

    The push to provide ever brighter coherent radiation sources has led to the creation of correspondingly bright electron beams. With billions of electrons packed into normalized emittances (phase space) below one micron, collective effects may dominate both the preservation and use of such ultra-bright beams. An important class of collective effects is due to density modulations within the bunch, or microbunching. Microbunching may be deleterious, as in the case of the Microbunching Instability (MBI), or it may drive radiation sources of unprecedented intensity, as in the case of Free Electron Lasers (FELs). In this work we begin by describing models of microbunching due to inherent beam shot noise, which sparks both the MBI as well as SLAC's Linac Coherent Light Source, the world's first hard X-ray laser. We first use this model to propose a mechanism for reducing the inherent beam shot noise as well as for predicting MBI effects. We then describe experimental measurements of the resulting microbunching at LCLS, including optical radiation from the MBI, as well as the first gain length and harmonic measurements from a hard X-ray FEL. In the final chapters, we describe schemes that use external laser modulations to microbunch light sources of the future. In these sections we describe coherent light source schemes for both both linacs and storage rings.

  14. A bunch compressor for small emittances and high peak currents at the VUV free-electron laser

    International Nuclear Information System (INIS)

    The free-electron laser (FEL) at the TESLA test facility (TTF2) produces laser-like radiation in the vacuum-ultraviolet (VUV) and soft X-ray regime. To reach the minimum radiation wavelength of 6nm, bunches of electrons with an energy of 1 GeV, a peak current of 2500 A and a normalized transverse emittance of less than 2 mm mrad are needed. The high peak current is achieved by compressing the electron bunches longitudinally in two magnetic chicanes. The first chicane is a modified version of bunch compressor 2 (BC2) which was used at TTF1. The second chicane is a new bunch compressor, the so called BC3. Since the charge density is very high when the bunches pass BC3, strong coherent synchrotron radiation (CSR) is emitted by the electrons and the transverse emittance of the bunch is diluted. Within this thesis different chicane layouts are compared analytically and by computer simulations to find a chicane layout which minimizes emittance dilution. A 6-bend S-shaped chicane is found to match the requirements of the VUV-FEL very well. CSR will not only lead to a growth of the transverse emittance, but also to an amplification of small modulations in energy and charge density. The dependence of the amplification on the modulation wavelength is studied for different chicane layouts and various electron bunch parameters. Computer simulations and results obtained by a theoretical model are compared. It is shown that density modulations can be amplified in BC3 by up to one order of magnitude. When the amplification in BC2 and BC3 is taken into account, the total amplification factor might reach up to two orders of magnitude. (orig.)

  15. COSYMA: Health effects models

    International Nuclear Information System (INIS)

    As one of the main objectives of the MARIA project (''Methods for Assessing the Radiological Impact of Accidents'') initiated by the Commission of the European Communities the program package COSYMA (''COde SYstem from MARIA'') for assessing the radiological and economic off-site consequences of accidental releases of radioactive material to the atmosphere has been jointly developed by the Kernforschungszentrum Karlsruhe (KfK), FRG, and the National Radiological Protection Board (NRPB), UK. COSYMA includes models and data for assessing a broad spectrum of accident consequences, and they are implemented in independent modules. The subject of this report are those modules, which incorporate models and data for assessing individual and collective risks for deterministic and stochastic health effects. It describes the models implemented, the mathematical algorithms and the required data. Examples are given and explained for the input and output part of the modules. (orig.)

  16. Genetic variation in sugar composition among muscadine, Florida hybrid bunch and bunch grape genotypes

    OpenAIRE

    Basha SM; Vasanthaiah HK; Kambiranda DM; Easwaran K; Queeley G

    2012-01-01

    Sheikh M Basha,1 Hemanth KN Vasanthaiah,1 Devaiah M Kambiranda,1 Kokila Easwaran,2 Gilbert Queeley31Center For Viticulture and Small Fruit Research, Florida A&M University, Tallahassee, FL, USA; 2Centre for Plant Molecular Biology, Tamil Nadu Agricultural University, Coimbatore, India; 3Cooperative Extension, College of Engineering Technology and Agricultural Sciences, Florida A&M University, Tallahassee, FL, USAAbstract: Sugar content and composition of the bunch grape (Vitis...

  17. Electron bunch length measurement at the radiation source ELBE

    International Nuclear Information System (INIS)

    In this study, measurement of electron bunch length at the ELBE Free Electron Laser (FEL) in the Forschungszentrum Dresden (FZD) is represented. Transition radiation is emitted when an electron passes the interface of two mediums of different dielectric constants. In case that the wavelength of the radiation is longer than the bunch length, coherent transition radiation (CTR) is emitted. The time profile of the CTR is a copy of the electron bunch longitudinal profile. The Martin-Puplett interferometer (MPI) is used to measure the autocorrelation function of the CTR pulse. The power spectrum and the bunch length information is obtained by Fourier transforming the measured autocorrelation function. There are different approaches for obtaining the bunch length from the MPI measurements. The data can be evaluated in the time domain as well as in the frequency domain. We can derive the longitudinal shapes of the electron bunch by analyzing the frequency information. The Measurement of the longitudinal electron bunch length is compared with the frequency domain method

  18. Mechanical Behavior of Electrospun Palmfruit Bunch Reinforced Polylactide Composite Fibers

    Science.gov (United States)

    Adeosun, S. O.; Akpan, E. I.; Gbenebor, O. P.; Peter, A. A.; Olaleye, Samuel Adebayo

    2016-01-01

    In this study, the mechanical characteristics of electrospun palm fruit bunch reinforced poly lactic acid (PLA) nanofiber composites using treated and untreated filler was examined. Poly lactic acid-palm fruit bunch-dichloromethane blends were electrospun by varying the concentration of the palm fruit bunch between 0 wt.% and 8 wt.%. A constant voltage of 26 kV was applied, the tip-to-collector distance was maintained at 27.5 cm and PLA-palm fruit bunch-dichloromethane (DCM) concentration of 12.5% (w/v) was used. The results revealed that the presence of untreated palm fruit bunch fillers in the electrospun PLA matrix significantly reduces the average diameters of the fibers, causing the formation of beads. As a result there are reductions in tensile strengths of the fibers. The presence of treated palm fruit bunch fillers in the electrospun PLA matrix increases the average diameters of the fibers with improvements in the mechanical properties. The optimal mechanical responses were obtained at 3 wt.% of the treated palm fruit bunch fillers in the PLA matrix. However, increase in the palm fruit fillers (treated and untreated) in the PLA matrix promoted the formation of beads in the nanofiber composites.

  19. LHC Pilot Bunches from the CERN PS Booster

    CERN Document Server

    Benedikt, Michael

    2003-01-01

    For the first commissioning phase of the LHC, a single proton bunch is required. The production of this so-called "LHC pilot bunch" will follow a different scheme than the one of the nominal LHC proton bunch train. Both the transverse and the longitudinal LHC bunch characteristics should already be established in the PS Booster. The parameter space for the LHC pilot bunch spans a factor 66 in beam brightness. To cover the whole parameter space, a mixture of several ingredients was required: intensity adjustment with low voltage rf-capture; definition of the transverse emittance with shavers; controlled blow-up followed by longitudinal shaving to define the longitudinal emittance. All beam variants were produced on harmonic two, with only one bunch being sent to the downstream accelerator chain. To cover also the lowest intensity side, the Linac beam was reduced by a factor 5 with a "sieve". The pilot bunches corresponding to the "corners" of the parameter space and a few selected inner reference points were s...

  20. Study on energy difference compensation for high intense multi-bunch electron beam generated by a photocathode RF-gun

    International Nuclear Information System (INIS)

    At Waseda University, we have been studying a high quality electron beam generation and its application experiments with a Cs-Te photocathode RF-Gun. To generate more intense and stable electron beam, we have been developing the cathode irradiating UV laser which consists of optical fiber amplifier and LD pumped amplifier. As the result, more than 100 multi-bunch electron beam with 1nC each bunch charge was obtained. However, it has to be considered that the accelerating voltage will decrease because of the beam loading effect. So we have studied the RF amplitude modulation technique to compensate the bunch by bunch energy difference. The energy difference will caused by transient accelerating voltage in RF-Gun cavity and beam loading effect. As the result of this compensation method, the energy difference has been compensated to 1% p-p, while 5% p-p without compensation. In this conference, we will report our multi-bunch electron beam linac system, the details of energy compensation method using the RF amplitude modulation and the results of beam experiment. (author)

  1. A matrix theory of the motion of an ellipsoidal bunch in a beam control system with a rectlinear optical axis and with space charge

    International Nuclear Information System (INIS)

    The motion of a 3-dimensional ellipsoidal bunch of charged particles in an arbitrary external electromagnetic field is considered taking into account the effect of space charge. The first approximation of the electromagnetic field within the bunch due to space charge has been found. The nonlinear matrix equation in the envelope variable space is written. An effective recursive computational method for the solution of the nonlinear beam envelope evolution is proposed

  2. DEGRADATION, MECHANO-PHYSICAL, AND MORPHOLOGICAL PROPERTIES OF EMPTY FRUIT BUNCH REINFORCED POLYESTER COMPOSITES

    OpenAIRE

    Abdul Khalil, H. P. S.; Irshad ul Haq Bhat; M. Y. Sartika

    2010-01-01

    This research aims to study the effects of degradation on mechanical, physical, and morphological properties of empty fruit bunch (EFB) fiber- reinforced polyester composites. The unsaturated polyester resin has been used to produce thermoset polymer composites. The reinforcing effect in composites was evaluated at various fiber loadings, including an overall fiber content (by weight) of 20% and 40%. The mechanical (tensile, flexural, and impact) and physical (density, moisture content, and w...

  3. Real-time monitoring of longitudinal electron bunch parameters by intensity-integrated and spectroscopic measurements of single coherent THz pulses

    International Nuclear Information System (INIS)

    High-gain free-electron lasers (FELs) generate intense and monochromatic photon pulses with few tens of femtosecond duration. For this purpose, electron beams are accelerated to relativistic energies and shrunk longitudinally down to micrometer size.The diagnosis of theses compressed electron bunches is a challenge especially for MHz bunch repetition rates as provided by the FEL FLASH in Hamburg. In this thesis, coherently emitted THz radiation of single electron bunches were investigated, on which the longitudinal structure is imprinted. Two instruments were used: First, the FLASH bunch compression monitors, relying on the integrated intensity measurement of diffraction radiation, were modified to determine the overall length of every bunch behind the two bunch compressors (BC). A model was developed showing that their response is independent of the exact bunch shape for lengths below 200 μm (rms). This could experimentally be verified in the range between 50 and 190 μm within 7% accuracy for themonitor behind the last BC by comparison with measurements with the transverse deflecting structure (TDS). Second, a single-shot spectrometer with five staged reflective blazed gratings has been designed, build and commissioned. With its two grating sets, the wavelength ranges from 5.5 to 44 μm and 45 to 440 μm can be simultaneously detected by 118 fast pyroelectric elements. Measurements based on transition radiation spectra were compared with profiles recorded by the TDS.The shape of the spectra as well as the reconstructed temporal profiles (using the Kramers-Kronig relation for phase retrieval) are in excellent agreement. For bunches with a charge of 50 pC, bunch lengths down to 5 μm (fhwm) could be detected.

  4. Bunching for Shorter Damping Rings for the ILC

    CERN Document Server

    Neuffer, David V

    2005-01-01

    A variant rearrangement of the bunch trains for the ILC that enables much shorter damping rings is presented. In a particular example the ~2280 bunches are regrouped into ~450 subtrains of five adjacent bunches. These subtrains are extracted from the damping rings at ~2.2 ms intervals, obtaining the 1ms macrobunch length of the baseline TESLA collider scenario. If the baseline damping rf frequency is 325 MHz and the kicker rise and fall times are ~20 ns, a ring circumference of ~4.5km is required. Variations of the scheme could easily reduce the circumference to ~3km, and faster kickers could reduce it even further.

  5. Measurement of bunch time-structure in KEK PF

    International Nuclear Information System (INIS)

    The time-structure of the bunches in the KEK-PF storage ring under the single bunch condition was measured by means of a photon counting system installed in beamline 21. When the jitter in the electronic system is negligible, the response of the whole system is finally determined by a transit time spread (TTS) of a photomultiplier (PMT). The TTS of the PMT was measured with a picosecond pulse laser system, pulse width of which was about 7 ps in FWHM. A current dependence of the longitudinal bunch shape was observed with the improved system and the authors found the increase of the asymmetry with the increase of the current

  6. Developing electron beam bunching technology for improving light sources

    International Nuclear Information System (INIS)

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The goal of this project was to develop a new electron bunch compression technology, experimentally demonstrate subpicosecond compression of bunches with charges on the order of 1 nC, and to theoretically investigate fundamental limitations to electron bunch compression. All of these goals were achieved, and in addition, the compression system built for this project was used to generate 22 nm light in a plasma-radiator light source

  7. Velocity bunching in travelling wave accelerator with low acceleration gradient

    CERN Document Server

    Huang, Rui-Xuan; Li, Wei-Wei; Jia, Qi-Ka

    2013-01-01

    We present the analytical and simulated results concerning the influences of the acceleration gradient in the velocity bunching process, which is a bunch compression scheme that uses a traveling wave accelerating structure as a compressor. Our study shows that the bunch compression application with low acceleration gradient is more tolerant to phase jitter and more successful to obtain compressed electron beam with symmetrical longitudinal distribution and low energy spread. We also present a transverse emittance compensation scheme to compensate the emittance growth caused by the increasing of the space charge force in the compressing process that is easy to be adjusted for different compressing factors.

  8. Electron Bunch Length Diagnostic With Coherent Smith-Purcell Radiation

    International Nuclear Information System (INIS)

    The authors have designed a new technique for measuring subpicosecond electron bunch lengths using coherent Smith-Purcell radiation. This new diagnostic technique involves passing the electron beam in close proximity of a grating with a period comparable to the electron bunch length. The emitted Smith-Purcell radiation will have a coherent component whose angular position and distribution are directly related to the electron bunch length and longitudinal profile, respectively. This new diagnostic technique is inherently simple, inexpensive and non-intercepting. The authors show that the new technique is also scaleable to femtosecond regime

  9. Chicane and wiggler based bunch compressors for future linear colliders

    International Nuclear Information System (INIS)

    In this paper, we discuss bunch compressors for future linear colliders. In the past, the bunch compression optics has been based upon achromatic cells using strong sextupoles to correct the dispersive and betatron chromaticity. To preserve the very small emittances required in most future collider designs, these schemes tend to have very tight alignment tolerances. Here, we describe bunch compressors based upon magnetic chicanes or wigglers which do need sextupoles to correct the chromatic emittance dilution. The dispersive chromaticity cancels naturally and the betatron chromaticity is not a significant source of emittance dilution. Thus, these schemes allow for substantially reduced alignment tolerances. Finally, we present a detailed design for the NLC linear collider

  10. Multi-Stage Bunch Compressors for the International Linear Collider

    OpenAIRE

    Tenenbaum, Peter G.; Raubenheimer, Tor O.; Wolski, Andrzej

    2005-01-01

    We present bunch compressor designs for the International Linear Collider (ILC) which achieve a reduction in RMS bunch length from 6 mm to 0.3 mm via multiple stages of compression, with stages of acceleration inserted between the stages of compression. The key advantage of multi-stage compression is that the maximum RMS energy spread is reduced to approximately 1 percent, compared to over 3 percent for a single-stage design. Analytic and simulation studies of the multi-stage bunch compr...

  11. Multi-Stage Bunch Compressors for the International Linear Collider

    International Nuclear Information System (INIS)

    We present bunch compressor designs for the International Linear Collider (ILC) which achieve a reduction in RMS bunch length from 6 mm to 0.3 mm via multiple stages of compression, with stages of acceleration inserted between the stages of compression. The key advantage of multi-stage compression is that the maximum RMS energy spread is reduced to approximately 1%, compared to over 3% for a single-stage design. Analytic and simulation studies of the multi-stage bunch compressors are presented, along with performance comparisons to a single-stage system. Parameters for extending the systems to a larger total compression factor are discussed

  12. Multi-Stage Bunch Compressors for the International Linear Collider

    CERN Document Server

    Tenenbaum, P G; Wolski, Andrzej

    2005-01-01

    We present bunch compressor designs for the International Linear Collider (ILC) which achieve a reduction in RMS bunch length from 6 mm to 0.3 mm via multiple stages of compression, with stages of acceleration inserted between the stages of compression. The key advantage of multi-stage compression is that the maximum RMS energy spread is reduced to approximately 1%, compared to over 3% for a single-stage design. Analytic and simulation studies of the multi-stage bunch compressors are presented, along with performance comparisons to a single-stage system. Parameters for extending the systems to a larger total compression factor are discussed.

  13. Analytical Approach to the Beam-Beam Interaction with the Hourglass Effect

    CERN Document Server

    AUTHOR|(CDS)2090622; Appleby, Robert Barrie

    2015-01-01

    The hourglass effect arises due to a coupling between the longitudinal and transverse bunch planes. This coupling will result in a charge density distribution that will vary parabolically through the Interaction Point (IP). Here a method of analytically determining the electric field a particle receives from a charge density distribution which varies parabolically when centred at the IP, is derived for a 2D transverse model of a Gaussian bunch.

  14. Anelamento e reguladores de crescimento: efeitos sobre as medidas biométricas e qualidade de cachos da videira 'Superior Seedless' Girdling and growth regulators: effects on the biometric measurements and quality of bunches of vine 'Superior Sedless'

    Directory of Open Access Journals (Sweden)

    Patrícia Coelho de Souza Leão

    2004-12-01

    Full Text Available Com o objetivo de se obter maior tamanho de baga, peso médio de cacho e produtividade, os cachos da variedade Superior Seedless foram pulverizados com ácido giberélico (1 + 20 mg.L-1, bioestimulante Crop Set® nas doses de 0,1 e 0,2% e com ou sem anelamento no caule. Esses tratamentos foram aplicados de forma isolada ou combinados entre si. O trabalho foi conduzido durante o período 2001-2002 (dois ciclos de produção, no Campo Experimental de Bebedouro da Embrapa Semi-Árido em Petrolina-PE. O delineamento experimental foi em blocos ao acaso, com 12 tratamentos e três repetições, sendo duas plantas por parcela. Não foram observadas diferenças significativas entre os tratamentos nos dois ciclos de produção. Entretanto, quando o ácido giberélico foi associado ao Crop Set® 0,1% e anelamento, observou-se uma tendência de aumento no peso de cachos, bem como no peso e tamanho de bagas na safra de 2001. Os cachos tratados com ácido giberélico apresentaram engaços mais grossos e pesados, embora não se observem diferenças significativas entre os tratamentos. Algumas plantas submetidas ao anelamento apresentaram problemas de cicatrização, o que provocou a morte das mesmas, recomendando-se evitar a realização desta prática nas condições em que se realizou este trabalho.Aiming to increase the berry size, weight of bunches and yield, the bunches of the cv. Superior Seedless was powdered with gibberelic acid (1 + 20 mg.L-1, bio-stimulant Crop Set® in the dosis of 0.1 and 0.2%. In adition was used the treatment known as girdling. Those treatments were applied in an isolated way or combined to each other. The work was carried out during 2001-2002 (two harvest seasons, in the Experimental Station of Bebedouro, Semi-arid Embrapa in Petrolina, Pernambuco State. The experimental design were in randomized blocks with 12 treatments and three replications. The differences among the treatments were not statistical significant in the two

  15. Phase modulation of the bucket stops bunch oscillations at the Fermilab Tevatron

    International Nuclear Information System (INIS)

    Bunches in the Tevatron are known to exhibit longitudinal oscillations which persist indefinitely. These oscillations are colloquially called 'dancing bunches.' Although the dancing proton bunches do not cause single bunch emittance growth or beam loss at injection, they lead to bunch lengthening at collisions. In Tevatron operations, a longitudinal damper has been built which stops this dance and damps out coupled bunch modes. Recent theoretical work predicts that the dance can also be stopped by an appropriate change in the bunch distribution. This paper describes the Tevatron experiments which support this theory.

  16. Phase modulation of the bucket stops bunch oscillations at the Fermilab Tevatron

    Energy Technology Data Exchange (ETDEWEB)

    Tan, C.Y.; Burov, A.; /Fermilab

    2012-04-02

    Bunches in the Tevatron are known to exhibit longitudinal oscillations which persist indefinitely. These oscillations are colloquially called 'dancing bunches.' Although the dancing proton bunches do not cause single bunch emittance growth or beam loss at injection, they lead to bunch lengthening at collisions. In Tevatron operations, a longitudinal damper has been built which stops this dance and damps out coupled bunch modes. Recent theoretical work predicts that the dance can also be stopped by an appropriate change in the bunch distribution. This paper describes the Tevatron experiments which support this theory.

  17. Investigation of transient processes at the DELTA electron storage ring using a digital bunch-by-bunch feedback system

    International Nuclear Information System (INIS)

    At the 1.5-GeV synchrotron radiation source DELTA, operated by the TU Dortmund University, intensive synchrotron radiation in the spectral range from hard X-rays to THz radiation is generated by the circular deflection of highly relativistic electron bunches. Interacting with the vacuum chamber wall, the electron bunches create electric fields, which can act back on subsequent bunches. With increasing beam current, the excitation is enhanced so that the electron beam is unstable, which means that the electron bunches oscillate longitudinally or transversely relative to their reference position. The oscillations reduce the quality of the synchrotron radiation and limit the maximum storable beam current. Within the scope of this thesis, the beam instabilities at the storage ring were systematically investigated. A digital bunch-by-bunch feedback system was installed and commissioned, which allows to detect and digitize the position of each electron bunch at each turn. Based on the input signal, a correction signal is calculated in order to suppress transverse and longitudinal oscillation of the bunches. In addition, it is possible to excite dedicated bunches. The systematic excitation of all coupled-bunch modes allowed for the first time to determine the damping rates of all 192 eigenmodes of the electron beam. The current dependence of the damping rates was investigated and an instability threshold was found. Besides the investigation of multibunch instabilities, single-bunch instabilities are discussed. In addition, the acquisition unit of the digital feedback system can be triggered on external events. This was used to investigate the injection process and beam losses. It was shown that the transverse feedback system increases the injection efficiency. Another aspect of this thesis is the improvement of the signal quality of ultrashort coherent synchrotron radiation pulses, which are generated by the short-pulse facility at DELTA. The short-pulse facility is based

  18. Investigation of transient processes at the DELTA electron storage ring using a digital bunch-by-bunch feedback system

    Energy Technology Data Exchange (ETDEWEB)

    Hoener, Markus

    2015-07-01

    At the 1.5-GeV synchrotron radiation source DELTA, operated by the TU Dortmund University, intensive synchrotron radiation in the spectral range from hard X-rays to THz radiation is generated by the circular deflection of highly relativistic electron bunches. Interacting with the vacuum chamber wall, the electron bunches create electric fields, which can act back on subsequent bunches. With increasing beam current, the excitation is enhanced so that the electron beam is unstable, which means that the electron bunches oscillate longitudinally or transversely relative to their reference position. The oscillations reduce the quality of the synchrotron radiation and limit the maximum storable beam current. Within the scope of this thesis, the beam instabilities at the storage ring were systematically investigated. A digital bunch-by-bunch feedback system was installed and commissioned, which allows to detect and digitize the position of each electron bunch at each turn. Based on the input signal, a correction signal is calculated in order to suppress transverse and longitudinal oscillation of the bunches. In addition, it is possible to excite dedicated bunches. The systematic excitation of all coupled-bunch modes allowed for the first time to determine the damping rates of all 192 eigenmodes of the electron beam. The current dependence of the damping rates was investigated and an instability threshold was found. Besides the investigation of multibunch instabilities, single-bunch instabilities are discussed. In addition, the acquisition unit of the digital feedback system can be triggered on external events. This was used to investigate the injection process and beam losses. It was shown that the transverse feedback system increases the injection efficiency. Another aspect of this thesis is the improvement of the signal quality of ultrashort coherent synchrotron radiation pulses, which are generated by the short-pulse facility at DELTA. The short-pulse facility is based

  19. Suppression of bunch transverse instabilities by the chamber asymmetry

    International Nuclear Information System (INIS)

    Axial asymmetry of a vacuum chamber gives rise to wake forces producing betatron tune shifts for tail particles. In the result, the bunch transverse instabilities could be suppressed or even eliminated

  20. MULTIPLE SINGLE BUNCH EXTRACTION TO THE AGS SWITCHYARD

    International Nuclear Information System (INIS)

    In this report we will describe the multiple single bunch extraction system as utilized to deliver beams to the Brookhaven's Alternating Gradient Synchrotron (AGS) switchyard area. We will describe modifications of the AGS switchyard, necessary to allow it to accept bunched beam, and results of the first commissioning of this system. The AGS Switchyard has for many years been used to simultaneously deliver (unbunched) resonant extracted beam to a set of fixed target experiments. In order to accommodate new fixed target experiments which require bunched beams, a method of sending the bunched beams to the AGS Switchyard was required. In addition, by using the AGS switchyard instead of the upstream section of the Brookhaven's Relativistic Heavy Ion Collider (RHIC) injection line the accelerators can be reconfigured quickly and efficiently for filling RHIC. We will present results of the commissioning of this system, which was done in January 2001

  1. STOCHASTIC COOLING OF HIGH-ENERGY BUNCHED BEAMS

    Energy Technology Data Exchange (ETDEWEB)

    BLASKIEWICZ,M.; BRENNAN, J.M.

    2007-06-25

    Stochastic cooling of 100 GeV/nucleon bunched beams has been achieved in the Relativistic Heavy Ion Collider (RHIC). The physics and technology of the longitudinal cooling system are discussed, and plans for a transverse cooling system are outlined.

  2. Maser on cyclotron resonance in nonresonant electron bunching mode

    International Nuclear Information System (INIS)

    For masers on cyclotron resonance (MCR) one introduces a new design based on the electron bunching in the field of non-resonance wave. The mentioned design ensures division into two sections of electron-wave interaction space at the expense of magnetic field profiling. It is shown that under certain conditions the particle motion towards the field of non-resonance wave (the first section) is followed by the efficient electron bunching without any essential change in their energy. In the second section where the value of the magnetic field is close to the resonance value one observes the efficient emission of a working wave by the bunched electron beam. So, the klystron type electron-wave interaction with separation of processes of particle bunching and emission takes place

  3. MULTIPLE SINGLE BUNCH EXTRACTION TO THE AGS SWITCHYARD.

    Energy Technology Data Exchange (ETDEWEB)

    BROWN,K.A.; AHRENS,L.; GASSNER,D.; GLENN,J.W.; ROSER,T.; SMITH,G.; TSOUPAS,N.; VAN ASSELT,W.; ZENO,K.

    2001-06-18

    In this report we will describe the multiple single bunch extraction system as utilized to deliver beams to the Brookhaven's Alternating Gradient Synchrotron (AGS) switchyard area. We will describe modifications of the AGS switchyard, necessary to allow it to accept bunched beam, and results of the first commissioning of this system. The AGS Switchyard has for many years been used to simultaneously deliver (unbunched) resonant extracted beam to a set of fixed target experiments. In order to accommodate new fixed target experiments which require bunched beams, a method of sending the bunched beams to the AGS Switchyard was required. In addition, by using the AGS switchyard instead of the upstream section of the Brookhaven's Relativistic Heavy Ion Collider (RHIC) injection line the accelerators can be reconfigured quickly and efficiently for filling RHIC. We will present results of the commissioning of this system, which was done in January 2001.

  4. A bunch compressor for the Next Linear Collider

    International Nuclear Information System (INIS)

    A bunch compressor design for the Next Linear Collider (NLC) is described. The compressor reduces the bunch length by a factor of 40 in two stages. The first stage at 2 GeV consists of an rf section and a wiggler. The second stage at 10 GeV is formed by an arc, an rf section, and a chicane. The final bunch phase is insensitive to initial phase errors and to beam loading in the intermediate S-band pre-linac. Residual longitudinal aberrations of the system are partially compensated. The bunch compressor encompasses a solenoid spin-rotator system at 2 GeV that allows complete control over the spin orientation

  5. Compensation of longitudinal nonlinearities in the NLC bunch compressor

    International Nuclear Information System (INIS)

    The X-Band linac of the Next Linear Collider (NLC) will accelerate bunches of about 100 μm rms length to energies of 250-750 GeV. The task of the NLC bunch compressor is to reduce the initial bunch length of 4-5 mm, at extraction from the damping ring, by a factor of 40, to the desired value. This task is accomplished in two separate stages. The first stage at 2 GeV consists of an rf section and a wiggler. The second stage at 10 GeV is formed by an arc, an rf section, and a chicane. The system is designed such that the final bunch phase is insensitive to initial phase errors and to beam-loading in the intermediate S-band pre-linac. Additional decelerating rf sections are employed to compensate significant longitudinal aberrations

  6. Compensation of Longitudinal Nonlinearities in the NLC Bunch Compressor

    International Nuclear Information System (INIS)

    The X-band linac of the Next Linear Collider (NLC) will accelerate bunches of about 100 μm rms length to energies of 250 endash 750 GeV. The task of the NLC bunch compressor is to reduce the initial bunch length of 4 endash 5 mm, at extraction from the damping ring, by a factor of 40, to the desired value. This task is accomplished in two separate stages. The first stage at 2 GeV consists of an rf section and a wiggler. The second stage at 10 GeV is formed by an arc, an rf section, and a chicane. The system is designed such that the final bunch phase is insensitive to initial phase errors and to beam-loading in the intermediate S-band pre-linac. Additional decelerating rf sections are employed to compensate significant longitudinal aberrations. copyright 1996 American Institute of Physics

  7. Matching sub-fs electron bunches for laser-driven plasma acceleration at SINBAD

    Science.gov (United States)

    Zhu, J.; Assmann, R. W.; Dorda, U.; Marchetti, B.

    2016-09-01

    We present theoretical and numerical studies of matching sub-femtosecond space-charge-dominated electron bunch into the Laser-plasma Wake Field Accelerator (LWFA) foreseen at the SINBAD facility. The longitudinal space-charge (SC) effect induced growths of the energy spread and longitudinal phase-space chirp are major issues in the matching section, which will result in bunch elongation, emittance growth and spot size dilution. In addition, the transverse SC effect would lead to a mismatch of the beam optics if it were not compensated for. Start-to-end simulations and preliminary optimizations were carried out in order to understand the achievable beam parameters at the entrance of the plasma accelerator.

  8. Bunch shape monitors using low energy secondary electron emission

    Science.gov (United States)

    Feschenko, A. V.

    1992-07-01

    To measure a longitudinal charge distribution in an ion linac beam it is preferable to apply bunch shape monitors using a low energy secondary emission electrons. Monitors of this type and their development are discussed. Different varieties of rf deflectors for a transverse modulation of secondary electrons are considered. Preliminary parameters of a bunch shape monitor for the SSC linac are presented. A detector to measure both longitudinal and transverse distributions of a two component ion beam is described.

  9. A bunch extension monitor for the SPIRAL2 LINAC

    OpenAIRE

    Vignet, J.L.; Revenko, R.

    2014-01-01

    Measurements of the bunch longitudinal shape of beamparticles are crucial for optimization and control ofLINAC beam parameters and maximization of itsintegrated luminosity. The non-interceptive bunchextension monitor for the LINAC of SPIRAL2 facility isbeing developed at GANIL. Five bunch extensionmonitors will be installed at the beginning of the LINACbetween superconducting cavities. The principle ofoperation is based on the registration of x-rays induced byions of accelerator beam interact...

  10. Bunch shape monitors using low energy secondary electron emission

    International Nuclear Information System (INIS)

    To measure a longitudinal charge distribution in an ion linac beam it is preferable to apply bunch shape monitors using a low energy secondary emission electrons. Monitors of this type and their development are discussed. Different varieties of rf deflectors for a transverse modulation of secondary electrons are considered. Preliminary parameters of a bunch shape monitor for the SSC linac are presented. A detector to measure both longitudinal and transverse distributions of a two component ion beam is described

  11. Status of longitudinal bunch diagnostics at the ANKA storage ring

    Energy Technology Data Exchange (ETDEWEB)

    Hiller, Nicole; Huttel, Erhard; Judin, Vitali; Kehrer, Benjamin; Klein, Marit; Marsching, Sebastian; Meuter, Christina; Mueller, Anke-Susanne; Nakneimueang, Somprasong; Nasse, Michael J.; Schuh, Marcel; Schwarz, Markus; Smale, Nigel [Karlsruher Institut fuer Technologie (Germany)

    2012-07-01

    ANKA, the synchrotron radiation facility at the Karlsruhe Institute of Technology, is operated in a special low-alpha-mode on a regular basis. With the recent installation of a visible light diagnostics beamline further studies of bunch lengthening and deformation could be performed with our streak camera for different machine settings within the low-alpha operation (different bunch currents, energies, alphas, RF voltages). This presentation gives an overview of the various studies.

  12. Discontinuity of Lyapunov Exponents Near Fiber Bunched Cocycles

    OpenAIRE

    Butler, Clark

    2015-01-01

    We give examples of locally constant $SL(2,\\mathbb{R})$-cocycles over a Bernoulli shift which are discontinuity points for Lyapunov exponents in the H\\"older topology and are arbitrarily close to satisfying the fiber bunching inequality. Backes, Brown, and the author have shown that the Lyapunov exponents vary continuously when restricted to the space of fiber bunched H\\"older continuous cocycles. Our examples give evidence that this theorem is optimal within certain families of H\\"older cocy...

  13. Torrefaction of Pelletized Oil Palm Empty Fruit Bunches

    OpenAIRE

    Nyakuma, Bemgba Bevan; Ahmad, Arshad; Johari, Anwar; Abdullah, Tuan Amran Tuan; Oladokun, Olagoke

    2015-01-01

    The torrefaction of oil palm Empty Fruit Bunch (EFB) briquettes was examined in this study. The results indicate that temperature significantly influenced the mass yield, energy yield and heating value of oil palm empty fruit bunch (OPEFB) briquettes during torrefaction. The solid uniform compact nature of EFB briquettes ensured a slow rate of pyrolysis or devolatization which enhanced torrefaction. The mass yield decreased from 79.70 % to 43.03 %, energy yield from 89.44 % to 64.27 % during ...

  14. Negative-mass mitigation of Coulomb repulsion for terahertz undulator radiation of electron bunches

    Energy Technology Data Exchange (ETDEWEB)

    Balal, N.; Magory, E. [Ariel University, Ariel 40700 (Israel); Bandurkin, I. V. [Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950 (Russian Federation); Bratman, V. L. [Ariel University, Ariel 40700 (Israel); Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950 (Russian Federation); Savilov, A. V. [Institute of Applied Physics, Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950 (Russian Federation); Lobachevsky State University of Nizhny Novgorod, 23 Gagarin Avenue, Nizhny Novgorod 603950 (Russian Federation)

    2015-10-19

    It is proposed to utilize the effect of negative mass for stabilization of the effective axial size of very dense and short electron bunches produced by photo-injector guns by using combined undulator and strong uniform magnetic fields. It has been shown that in the “abnormal” regime, an increase in the electron energy leads to a decrease in the axial velocity of the electron; due to the negative-mass effect, the Coulomb repulsion of electrons leads to their attraction and formation of a fairly stable and compact bunch “nucleus.” An undulator with a strong uniform magnetic field providing the negative-mass effect is designed for an experimental source of terahertz radiation. The use of the negative-mass regime in this experiment should result in a long-pulse coherent spontaneous undulator emission from a short dense moderately relativistic (5.5 MeV) photo-injector electron bunch with a high (up to 20%) efficiency and a narrow frequency spectrum.

  15. Negative-mass mitigation of Coulomb repulsion for terahertz undulator radiation of electron bunches

    International Nuclear Information System (INIS)

    It is proposed to utilize the effect of negative mass for stabilization of the effective axial size of very dense and short electron bunches produced by photo-injector guns by using combined undulator and strong uniform magnetic fields. It has been shown that in the “abnormal” regime, an increase in the electron energy leads to a decrease in the axial velocity of the electron; due to the negative-mass effect, the Coulomb repulsion of electrons leads to their attraction and formation of a fairly stable and compact bunch “nucleus.” An undulator with a strong uniform magnetic field providing the negative-mass effect is designed for an experimental source of terahertz radiation. The use of the negative-mass regime in this experiment should result in a long-pulse coherent spontaneous undulator emission from a short dense moderately relativistic (5.5 MeV) photo-injector electron bunch with a high (up to 20%) efficiency and a narrow frequency spectrum

  16. E-Cloud Drivent Single-Bunch Instabilities in PS2

    Energy Technology Data Exchange (ETDEWEB)

    Venturini, M.; Furman, M.; Penn, G.; Secondo, R.; Vay, J-L.; De Maria, R.; Papaphilippou, Y.; Rumolo, G.

    2010-05-23

    One of the proposals under consideration for future upgrades of the LHC injector complex entails the replacement of the PS with the PS2, a longer circumference and higher energy synchrotron, with electron cloud effects representing a potentially serious limitation to the achievement of the upgrade goals. We report on ongoing numerical studies aiming at estimating the e-cloud density threshold for the occurrence of single bunch instabilities.

  17. E-cloud Driven Single-bunch Instabilities in PS2

    CERN Document Server

    Venturini, Marco; Penn, Gregory; Secondo, Raffaello; Vay, Jean-Luc; De Maria, Riccardo; Papaphilippou, Yannis; Rumolo, Giovanni

    2010-01-01

    One of the proposals under consideration for future upgrades of the LHC injector complex entails the replacement of the PS with the PS2, a longer circumference and higher energy synchrotron, with electron cloud effects representing a potentially serious limitation to the achievement of the upgrade goals. We report on ongoing numerical studies aiming at estimating the e-cloud density threshold for the occurrence of single bunch instabilities

  18. POTENTIAL OF FINES AS REINFORCING FIBRES IN ALKALINE PEROXIDE PULP OF OIL PALM EMPTY FRUIT BUNCH

    OpenAIRE

    Nurul H. Kamaludin,; Arniza Ghazali,; Wan Daud Wanrosli

    2012-01-01

    Pulp from the alkaline peroxide mechanical pulping (APMP) of oil palm empty fruit bunch, EFB, was fractionated with varying mesh-size screens to examine the effects imposed by size-specific fines on the produced pulp network. Occurring mainly as a result of refining, fines elements with dimensions almost resembling EFB fibres were the long tube-like tapered vessels from the arrays of adjoined cell walls detached along the perforation lines. These fibrillated vessel elements constituting the P...

  19. E-Cloud Drivent Single-Bunch Instabilities in PS2

    International Nuclear Information System (INIS)

    One of the proposals under consideration for future upgrades of the LHC injector complex entails the replacement of the PS with the PS2, a longer circumference and higher energy synchrotron, with electron cloud effects representing a potentially serious limitation to the achievement of the upgrade goals. We report on ongoing numerical studies aiming at estimating the e-cloud density threshold for the occurrence of single bunch instabilities.

  20. Photon antibunching and bunching in a ring-resonator waveguide quantum electrodynamics system.

    Science.gov (United States)

    Chen, Zihao; Zhou, Yao; Shen, Jung-Tsung

    2016-07-15

    We numerically investigate the photonic state generation and its nonclassical correlations in a ring-resonator waveguide quantum electrodynamics system. Specifically, we discuss photon antibunching and bunching in various scenarios, including the imperfect resonator with backscattering and dissipations. Our numerical results indicate that an imperfect ring resonator with backscattering can enhance the quality of antibunching. In addition, we also identify the quantum photonic halo phenomenon in the photon scattering dynamics and the shoulder effect in the second-order correlation function. PMID:27420523

  1. E-Cloud Drivent Single-Bunch Instabilities in PS2

    OpenAIRE

    Venturini, M.

    2010-01-01

    One of the proposals under consideration for future upgrades of the LHC injector complex entails the replacement of the PS with the PS2, a longer circumference and higher energy synchrotron, with electron cloud effects representing a potentially serious limitation to the achievement of the upgrade goals. We report on ongoing numerical studies aiming at estimating the e-cloud density threshold for the occurrence of single bunch instabilities.

  2. Downramp-assisted underdense photocathode electron bunch generation in plasma wakefield accelerators

    CERN Document Server

    Knetsch, Alexander; Wittig, Georg; Groth, Henning; Xi, Yunfeng; Deng, Aihua; Rosenzweig, James Benjamin; Bruhwiler, David Leslie; Smith, Johnathan; Jaroszynski, Dino Anthony; Sheng, Zheng-Ming; Manahan, Grace Gloria; Xia, Guoxing; Jamison, Steven; Hidding, Bernhard

    2014-01-01

    It is shown that the requirements for high quality electron bunch generation and trapping from an underdense photocathode in plasma wakefield accelerators can be substantially relaxed through localizing it on a plasma density downramp. This depresses the phase velocity of the accelerating electric field until the generated electrons are in phase, allowing for trapping in shallow trapping potentials. As a consequence the underdense photocathode technique is applicable by a much larger number of accelerator facilities. Furthermore, dark current generation is effectively suppressed.

  3. Hybrid Fibre Polylactide Acid Composite with Empty Fruit Bunch: Chopped Glass Strands

    OpenAIRE

    K. Y. Tshai; A. B. Chai; Kong, I.; Hoque, M.E; Tshai, K. H.

    2014-01-01

    Hybrid polylactide acid (PLA) composites reinforced with palm empty fruit bunch (EFB) and chopped strand E-glass (GLS) fibres were investigated. The hybrid fibres PLA composite was prepared through solution casting followed by pelletisation and subsequent hot compression press into 1 mm thick specimen. Chloroform and dichloromethane were used as solvent and their effectiveness in dissolving PLA was reported. The overall fibre loading was kept constant at volume fraction, Vf, of 20% while the ...

  4. PYROLYSIS OF EMPTY FRUIT BUNCHES: INFLUENCE OF TEMPERATURE ON THE YIELDS AND COMPOSITION OF GASEOUS PRODUCT

    OpenAIRE

    Mohamad Azri Sukiran; Loh Soh Kheang; Nasrin Abu Bakar; Choo Yuen May

    2014-01-01

    With the increasing concern on fossil fuel depletion and environmental problems, the utilization of renewable biomass resources is expected to play an important role in the future. Biomass can be converted into a variety of fuels and chemicals by different processes; one of which is pyrolysis that has been subjected to extensive research in recent years. In this study, pyrolysis of oil palm Empty Fruit Bunches (EFB) was investigated using a quartz fluidised-fixed bed reactor. The effects of p...

  5. Production of reducing sugar from oil palm empty fruit bunch (EFB) cellulose fibres via acid hydrolysis

    OpenAIRE

    Siew Xian Chin; Chin Hua Chia; Sarani Zakaria

    2013-01-01

    Cellulosic fibre of oil palm empty fruit bunches (EFB) were used as a raw material for acid hydrolysis using mineral acids (H2SO4 and HCl) to produce reducing sugar at moderate temperature and atmospheric pressure. Experiments were carried out to investigate the effect of the hydrolysis parameters, including acid concentration, temperature, and reaction time, on the total reducing sugar (TRS) yield with the aid of response surface methodology (RSM). The preliminary hydrolysis studies of the E...

  6. Lie algebraic analysis for the nonlinear transport of intense bunched beam in electrostatic quadrupoles

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhuo; L(U) Jian-Qin

    2008-01-01

    In this paper, the nonlinear transport of intense bunched beams in electrostatic quadrupoles is analyzed using the Lie algebraic method, and the results are briefly presented of the linear matrix approximation and the second order correction of particle trajectory in the state space. Beam having K-V distribution and Gaussian distribution approximation are respectively considered. A brief discussion is also given of the total effects of the quadrupole and the space charge forces on the evolution of the beam envelope.

  7. Transverse C-band deflecting structure for longitudinal electron-bunch-diagnosis in XFEL “SACLA”

    Energy Technology Data Exchange (ETDEWEB)

    Ego, H., E-mail: ego@spring8.or.jp [Japan Synchrotron Radiation Research Institute (JASRI), Kouto, Sayo, Hyogo (Japan); Maesaka, H.; Sakurai, T.; Otake, Y. [RIKEN SPring-8 Center, Kouto, Sayo, Hyogo (Japan); Hashirano, T.; Miura, S. [Mitsubishi Heavy Industries, Ltd. (MHI), Itozaki, Mihara, Hiroshima (Japan)

    2015-09-21

    In the 8 GeV compact X-ray FEL “SACLA,” a single bunch of electrons is compressed to a duration of approximately 30 fs to yield a peak current of 3 kA, which creates brilliant self-amplified spontaneous emission. To measure the longitudinal profile of an ultrashort electron bunch and verify the compression, we developed a high-gradient C-band RF deflecting structure 1.8 m long and periodically loaded with racetrack-shaped irises. The irises generated a high deflection gradient for the vertically deflecting HEM11-5π/6 dipole mode and suppressed rotation of the deflection plane. The two structures were fabricated and generated a stable total deflecting voltage exceeding 60 MV and revealed the longitudinal electron-bunch profile with an effective time resolution of approximately 10 fs.

  8. Longitudinal bunch dynamics study with coherent synchrotron radiation

    Science.gov (United States)

    Billinghurst, B. E.; Bergstrom, J. C.; Baribeau, C.; Batten, T.; May, T. E.; Vogt, J. M.; Wurtz, W. A.

    2016-02-01

    An electron bunch circulating in a storage ring constitutes a dynamical system with both longitudinal and transverse degrees of freedom. Through a self-interaction with the wakefields created by the bunch, certain of these degrees may get excited, defining a set of eigenmodes analogous to a spectroscopic series. The present study focuses on the longitudinal modes of a single bunch. The excitation of a mode appears as an amplitude modulation at the mode frequency of the coherent synchrotron radiation (CSR) emitted by the bunch. The modulations are superimposed on a much larger continuum from CSR emission in the continuous mode. A given eigenmode is classified by the integer m which is the ratio of the mode frequency to the synchrotron frequency. The present measurements extend up to m =8 and focus on the region near the instability thresholds. At threshold the modes are excited sequentially, resembling a staircase when the mode frequencies are plotted as a function of bunch length or synchrotron frequency. Adjacent modes are observed to coexist at the boundaries between the modes. An energy-independent correlation is observed between the threshold current for an instability and the corresponding zero-current bunch length. Measurements were made at five beam energies between 1.0 and 2.9 GeV at the Canadian Light Source. The CSR was measured in the time domain using an unbiased Schottky diode spanning 50-75 GHz.

  9. Bunch modulation in LWFA blowout regime

    Czech Academy of Sciences Publication Activity Database

    Vyskočil, Jiří; Klimo, Ondřej; Vieira, J.; Korn, Georg

    Bellingham : SPIE, 2015 - (Ledingham, K.; Esarey, E.; Spohr, K.; Schroeder, C.; McKenna, P.; Gruner, F.; Bolton, P.), "95141E-1"-"95141E-7" ISBN 978-1-62841-635-0. ISSN 0277-786X. [Laser Acceleration of Electrons, Protons, and Ions III and Medical Applications of Laser-Generated Beams of Particles III. Praha (CZ), 13.04.2015-15.04.2015] R&D Projects: GA MŠk ED1.1.00/02.0061; GA MŠk EE2.3.20.0279; GA MŠk EE.2.3.20.0087 Grant ostatní: ELI Beamlines(XE) CZ.1.05/1.1.00/02.0061; LaserZdroj (OP VK 3)(XE) CZ.1.07/2.3.00/20.0279; OP VK 2 LaserGen(XE) CZ.1.07/2.3.00/20.0087 Institutional support: RVO:68378271 Keywords : electron injection * bunch modulation * LWFA Subject RIV: BC - Control Systems Theory

  10. An improved injector bunching geometry for ATLAS

    Indian Academy of Sciences (India)

    Richard C Pardo; J Bogaty; B E Clifft; S Sherementov; P Strickhorn

    2002-12-01

    The bunching system of the ATLAS positive ion injector (PII) has been improved by relocating the harmonic buncher to a point significantly closer to the second stage sine-wave buncher and the injector LINAC. The longitudinal optics design has also been modified and now employs a virtual waist from the harmonic buncher feeding the second stage sine-wave buncher. This geometry improves the handling of space charge for high-current beams, significantly increases the capture fraction into the primary rf bucket and reduces the capture fraction of the unwanted parasitic rf bucket. Total capture and transport through the PII has been demonstrated as high as 80% of the injected dc beam while the population of the parasitic, unwanted rf bucket is typically less than 3% of the total transported beam. To remove this small residual parasitic component a new traveling-wave transmission-line chopper has been developed reducing both transverse and longitudinal emittance growth from the chopping process. This work was supported by the U.S. Department of Energy under contract W-31-109-ENG-38.

  11. High bandwidth pickup design for bunch arrival-time monitors for free-electron laser

    Science.gov (United States)

    Angelovski, Aleksandar; Kuhl, Alexander; Hansli, Matthias; Penirschke, Andreas; Schnepp, Sascha M.; Bousonville, Michael; Schlarb, Holger; Bock, Marie Kristin; Weiland, Thomas; Jakoby, Rolf

    2012-11-01

    In this paper, we present the design and realization of high bandwidth pickup electrodes with a cutoff frequency above 40 GHz. The proposed cone-shaped pickups are part of a bunch arrival-time monitor designed for high (>500pC) and low (20 pC) bunch charge operation mode providing for a time resolution of less than 10 fs for both operation modes. The proposed design has a fast voltage response, low ringing, and a resonance-free spectrum. For assessing the influence of manufacturing tolerances on the performance of the pickups, an extensive tolerance study has been performed via numerical simulations. A nonhermetic model of the pickups was built for measurement and validation purposes. The measurement and simulation results are in good agreement and demonstrate the capability of the proposed pickup system to meet the given specifications.

  12. High Bandwidth Pickup Design for Bunch Arrival-time Monitors for Free-Electron Laser

    CERN Document Server

    Angelovski, Aleksandar; Hansli, Matthias; Penirschke, Andreas; Schnepp, Sascha M; Bousonville, Michael; Schlarb, Holger; Bock, Marie Kristin; Weiland, Thomas; Jakoby, Rolf

    2012-01-01

    In this paper, we present the design and realization of high bandwidth pickup electrodes with a cutoff frequency above 40 GHz. The proposed cone-shaped pickups are part of a bunch arrival-time monitor (BAM) designed for high (> 500 pC) and low (20 pC) bunch charge operation mode providing for a time resolution of less than 10 fs for both operation modes. The proposed design has a fast voltage response, low ringing, and a resonance-free spectrum. For assessing the influence of manufacturing tolerances on the performance of the pickups, an extensive tolerance study has been performed via numerical simulations. A non-hermetic model of the pickups was built for measurement and validation purposes. The measurement and simulation results are in good agreement and demonstrate the capability of the proposed pickup system to meet the given specifications.

  13. Parametric (quasi-Cherenkov) cooperative radiation produced by electron bunches in natural or photonic crystals

    CERN Document Server

    Anishchenko, S V

    2013-01-01

    We use numerical modeling to study the features of parametric (quasi-Cherenkov) cooperative radiation arising when an electron bunch passes through a crystal (natural or artificial) under the conditions of dynamical diffraction of electromagnetic waves in the presence of shot noise. It is shown that in both Laue and Bragg diffraction cases, parametric radiation consists of two strong pulses: one emitted at small angles with respect to the particle velocity direction and the other emitted at large angles to it. Under Bragg diffraction conditions, the intensity of parametric radiation emitted at small angles to the particle velocity direction reaches saturation at sufficiently smaller number of particles than the intensity of parametric radiation emitted at large angles. Under Laue diffraction conditions, every pulse contains two strong peaks, which are associated with the emission of electromagnetic waves at the front and back ends of the bunch. The presence of noise causes a chaotic signal in the interval bet...

  14. A Novel Diagnostics of Ultrashort Electron Bunches Based on Detection of Coherent Radiation from Bunched Electron Beam in an Undulator

    CERN Document Server

    Saldin, Evgeny L; Yurkov, Mikhail V

    2004-01-01

    We propose a new method for measurements of the longitudinal profile of 100 femtosecond electron bunches for X-ray Free Electron Lasers (XFELs). The method is based on detection of coherent undulator radiation produced by modulated electron beam. Seed optical quantum laser is used to produce exact optical replica of ultrashort electron bunches. The replica is generated in apparatus which consists of an input undulator (energy modulator), and output undulator (radiator) separated by a dispersion section. The radiation in the output undulator is excited by the electron bunch modulated at the optical wavelength and rapidly reaches a hundred-MW-level power. We then use the now-standard method of ultrashort laser pulse-shape measurement, a tandem combination of autocorrelator and spectrum (FROG -- frequency resolved optical gating) providing real-time single-shot measurements of the electron bunch structure. The big advantage of proposed technique is that it can be used to determine the slice energy spread and emi...

  15. Hydrolysis of Oil Palm Empty Fruit Bunch Fibers to Produce Sugar Hydrolyzate as Raw Material for Bioethanol Production

    OpenAIRE

    Fitriani Kasim; Anwar Kasim

    2013-01-01

    A study conducted to see the effect of the regulation and control of temperature on the length of the hydrolysis of oil palm empty fruit bunches fiber and the resulting hydrolyzate sugar levels, which will be planned to be used as raw material for bioethanol. Therefore do oil palm empty fruit bunches fiber hydrolysis with sulfuric acid (H2SO4) at low concentrations (1%) using an autoclave with a temperature of 120 ° C and 130 ° C, and the time for 30, 60, 90, 120 minutes. After that the obser...

  16. On compensating tune spread induced by space charge in bunched beams

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko V. N.; Wang, G.

    2014-05-09

    Space charge effects play significant role in modern-day accelerators. These effects frequently constrain attainable beam parameters in an accelerator, or, in an accelerator chain. They also could limit the luminosity of hadron colliders operating either at low energies or with a sub-TeV high brightness hadron beams. The latter is applied for strongly cooled proton and ion beams in eRHIC – the proposed future electron-ion collider at Brookhaven National Laboratory. A number of schemes for compensating space charge effects in a coasting (e.g. continuous) hadron beam were proposed and some of them had been tested. Using a proper transverse profile of the electron beam (or plasma column) for a coasting beam would compensate both the tune shift and the tune spread in the hadron beam. But all of these methods do not address the issue of tune spread compensation of a bunched hadron beam, e.g. the tune shift dependence on the longitudinal position inside the bunch. In this paper we propose and evaluate a novel idea of using a co-propagating electron bunch with miss-matched longitudinal velocity to compensate the space charge induced tune-shift and tune spread. We present a number of practical examples of such system.

  17. A new technique for compression of tree bunches from young stands

    Energy Technology Data Exchange (ETDEWEB)

    Bergstroem, D.; Nordfjell, T. (The Department of Forest Resource Management, The Swedish University of Agriculture Science, Umeaa (Sweden)); Bergsten, U. (The Department of Forest Ecology and Management, The Swedish University of Agriculture Science, Umeaa (Sweden))

    2007-07-01

    Trees or parts of trees from young stands could provide valuable biomass for energy production. However, they are voluminous, resulting in low load densities and poor efficiencies for forwarder and subsequent handling operations. Furthermore, the fresh raw material generally has high proportions of foliage and, thus, high mineral (ash) contents, so much of the foliage should be left, evenly distributed in the stand after harvesting, if possible, in order to reduce losses of nutrients and improve the material's combustion parameters. The objective of the study reported here was to evaluate the potential utility of a new, prototype machine for compressing bunched trees from young stands. It uses aggressive feed rollers to break and flatten branches to compress bunches during processing, and substantially defoliates the bunched stems. In this study Pinus sylvestris trees of two size classes (A and B, with diameters at breast height, dbh, of 5-8 cm and 12-15 cm, respectively) were used to test the system. Trees were manually felled and gathered into bunches that were subsequently processed using the prototype. Bucking was done by hand, and the bucked trees were bundled by tightening nylon string with a force of 100 N around each bucked bunch at the root end, the middle and the top end. Samples of bunches were chipped and sub-samples were taken to measure their ash and moisture contents. The results showed that for type A bundles the compression technique caused an 11% reduction in weight (due to losses of needles and fine branches), an 0.3 % reduction in ash content and a 68% increase in bulk density. Corresponding figures for type B bundles were a 150/o decrease in weight, a 0.4 % decrease in ash content and a 150% increase in bulk density. The results show that the effects are greatest when processing larger trees. The tested equipment could be attached to a harvester head or mounted on a forwarder-crane. Alternatively, it could be mounted as a separate unit, e

  18. Mode-switching induced super-thermal bunching in quantum-dot microlasers

    Science.gov (United States)

    Redlich, Christoph; Lingnau, Benjamin; Holzinger, Steffen; Schlottmann, Elisabeth; Kreinberg, Sören; Schneider, Christian; Kamp, Martin; Höfling, Sven; Wolters, Janik; Reitzenstein, Stephan; Lüdge, Kathy

    2016-06-01

    The super-thermal photon bunching in quantum-dot (QD) micropillar lasers is investigated both experimentally and theoretically via simulations driven by dynamic considerations. Using stochastic multi-mode rate equations we obtain very good agreement between experiment and theory in terms of intensity profiles and intensity-correlation properties of the examined QD micro-laser’s emission. Further investigations of the time-dependent emission show that super-thermal photon bunching occurs due to irregular mode-switching events in the bimodal lasers. Our bifurcation analysis reveals that these switchings find their origin in an underlying bistability, such that spontaneous emission noise is able to effectively perturb the two competing modes in a small parameter region. We thus ascribe the observed high photon correlation to dynamical multistabilities rather than quantum mechanical correlations.

  19. Fast polycrystalline CdTe detectors for bunch-by-bunch luminosity monitoring in the LHC

    CERN Document Server

    Brambilla, A; Jolliot, M; Bravin, E

    2008-01-01

    The luminosity at the four interaction points of the Large Hadron Collider (LHC) must be continuously monitored in order to provide an adequate tool for the control and optimisation of beam parameters. Polycrystalline cadmium telluride (CdTe) detectors have previously been tested, showing their high potential to fulfil the requirements of luminosity measurement in the severe environment of the LHC interaction regions. Further, the large signal yield and the fast response time should allow bunch-by-bunch measurement of the luminosity at 40 MHz with high accuracy. Four luminosity monitors with two rows of five polycrystalline CdTe detectors each have been fabricated and will be installed at both sides of the low-luminosity interaction points ALICE and LHC-b. A detector housing was specially designed to meet the mechanical constraints in the LHC. A series of elementary CdTe detectors were fabricated and tested, of which 40 were selected for the luminosity monitors. A sensitivity of 104 electrons per minimum ioni...

  20. Analysis of the electron cloud observations with 25 ns bunch spacing at LHC

    CERN Document Server

    Iadarola, G; Rumolo, G; Arduini, G; Baglin, V; Banfi, D; Claudet, S; Dominguez, O; Esteban Müller, J; Pieloni, T; Shaposhnikova, E; Tavian, L; Zannini, C; Zimmermann, F

    2014-01-01

    Electron Cloud (EC) effects have been identified as a major performance limitation for the Large Hadron Collider (LHC) when operating with the nominal bunch spacing of 25 ns. During the LHC Run 1 (2010 - 2013) the luminosity production mainly used beams with 50 ns spacing, while 25 ns beams were only employed for short periods in 2011 and 2012 for test purposes. On these occasions, observables such as pressure rise, heat load in the cold sections as well as clear signatures on bunch-by-bunch emittance blow up, particle loss and energy loss indicated the presence of an EC in a large portion of the LHC. The analysis of the recorded data, together with EC build up simulations, has led to a significant improvement of our understanding of the EC effect in the different components of the LHC. Studies were carried out both at injection energy (450 GeV) and at top energy (4 TeV) aiming at determining the energy dependence of the EC formation and its impact on the quality of the proton beam.

  1. Numerical modelling of Bose-Einstein correlations

    CERN Document Server

    Utyuzh, O V; Wlodarczyk, Z

    2001-01-01

    We propose extension of the algorithm for numerical modelling of Bose-Einstein correlations (BEC), which was presented some time ago in the literature. It is formulated on quantum statistical level for a single event and uses the fact that identical particles subjected to Bose statistics do bunch themselves, in a maximal possible way, in the same cells in phase-space. The bunching effect is in our case obtained in novel way allowing for broad applications and fast numerical calculations. First comparison with $e^+e^-$ annihilations data performed by using simple cascade hadronization model is very encouraging.

  2. Different temporal patterns of vector soliton bunching induced by polarization-dependent saturable absorber

    Science.gov (United States)

    Chen, Wei-Cheng; Chen, Guo-Jie; Han, Ding-An; Li, Bin

    2014-06-01

    A fiber laser with either a polarization-independent semiconductor saturable absorption mirror (PID-SESAM) or a polarization-dependent SESAM (PD-SESAM) as a passive mode-locker is constructed for obtaining the vector soliton bunching. The temporal patterns of the soliton bunching generated from the fiber laser with a PD-SESAM are much more abundant than that in fiber laser with a PID-SESAM. Only the vibrating soliton bunching is generated from the fiber laser with a PID-SESAM. However, there are another three interesting temporal patterns of the soliton bunching generated from the fiber laser with a PD-SESAM except for the vibrating soliton bunching. They are variable length soliton bunching, breathing soliton bunching and stable soliton bunching along the slow axis induced by polarization instability. It is found that the polarization property of the saturable absorber plays a pivotal role for achieving different temporal patterns of the soliton bunching.

  3. Production of high intensity electron bunches for the SLAC Linear Collider

    Energy Technology Data Exchange (ETDEWEB)

    James, M.B.

    1987-08-01

    This thesis describes the design and performance of a high intensity electron injecfor for the SLAC Linear Collider. Motivation for the collider and the specifications for the injector are discussed. An analytic theory of the bunching and capture of electrons by rf fields is discussed in the limit of low space charge and small signal. The design and performance of SLAC's main injector are described to illustrate a successful application of this theory. The bunching and capture of electrons by rf fields are then discussed in the limit of high space charge and large signal, and a description of the design of the collider injector follows. In the limit of high space charge forces and large rf signals, the beam dynamics are considerably more complex and numerical simulations are required to predict particle motion. A computer code which models the longitudinal dynamics of electrons in the presence of space charge and rf fields is described. The results of the simulations, the resulting collider injector design and the various components which make up the collider injector are described. These include the gun, subharmonic bunchers, traveling-wave buncher and velocity-of-light accelerator section. Finally, the performance of the injector is described including the beam intensity, bunch length, transverse emittance and energy spectrum. While the final operating conditions differ somewaht from the design, the performance of the collider injector is in good agreement with the numerical simulations and meets all of the collider specifications. 28 refs.

  4. Production of high intensity electron bunches for the SLAC Linear Collider

    International Nuclear Information System (INIS)

    This thesis describes the design and performance of a high intensity electron injecfor for the SLAC Linear Collider. Motivation for the collider and the specifications for the injector are discussed. An analytic theory of the bunching and capture of electrons by rf fields is discussed in the limit of low space charge and small signal. The design and performance of SLAC's main injector are described to illustrate a successful application of this theory. The bunching and capture of electrons by rf fields are then discussed in the limit of high space charge and large signal, and a description of the design of the collider injector follows. In the limit of high space charge forces and large rf signals, the beam dynamics are considerably more complex and numerical simulations are required to predict particle motion. A computer code which models the longitudinal dynamics of electrons in the presence of space charge and rf fields is described. The results of the simulations, the resulting collider injector design and the various components which make up the collider injector are described. These include the gun, subharmonic bunchers, traveling-wave buncher and velocity-of-light accelerator section. Finally, the performance of the injector is described including the beam intensity, bunch length, transverse emittance and energy spectrum. While the final operating conditions differ somewaht from the design, the performance of the collider injector is in good agreement with the numerical simulations and meets all of the collider specifications. 28 refs

  5. Thermophilic anaerobic co-digestion of oil palm empty fruit bunches with palm oil mill effluent for efficient biogas production

    DEFF Research Database (Denmark)

    O-Thong, Sompong; Boe, Kanokwan; Angelidaki, Irini

    2012-01-01

    The effect of pretreatment methods for improved biodegradability and biogas production of oil palm empty fruit bunches (EFB) and its co-digestion with palm oil mill effluent (POME) was investigated. The maximum methane potential of POME was 502mL CH4/gVS-added corresponding to 33.2m3 CH4/ton POME...

  6. Enhancing Light-Atom Interactions via Atomic Bunching

    CERN Document Server

    Schmittberger, Bonnie L

    2014-01-01

    There is a broad interest in enhancing the strength of light-atom interactions to the point where injecting a single photon induces a nonlinear material response. Here, we show theoretically that sub-Doppler-cooled, two-level atoms that are spatially organized by weak optical fields give rise to a nonlinear material response that is greatly enhanced beyond that attainable in a homogeneous gas. Specifically, in the regime where the intensity of the applied optical fields is much less than the off-resonant saturation intensity, we show that the third-order nonlinear susceptibility scales inversely with atomic temperature and, due to this scaling, can be two orders of magnitude larger than that of a homogeneous gas for typical experimental parameters. As a result, we predict that spatially bunched two-level atoms can exhibit single-photon nonlinearities. Our model is valid for all atomic temperature regimes and simultaneously accounts for the back-action of the atoms on the optical fields. Our results agree with...

  7. Stochastic cooling of bunched beams from fluctuation and kinetic theory

    Energy Technology Data Exchange (ETDEWEB)

    Chattopadhyay, S.

    1982-09-01

    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.

  8. Stochastic cooling of bunched beams from fluctuation and kinetic theory

    International Nuclear Information System (INIS)

    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

  9. THz-spectroscopy for bunch length measurement at the TESLA test facility TTF

    International Nuclear Information System (INIS)

    The operation of a free electron laser in the VUV regime puts stringent demands on the beam quality of an electron linear accelerator. For this reason the beam diagnostic technique of fourier-transform spectroscopy has been further developed to determine the longitudinal charge profile of the electron bunch with the required precision. Transition, diffraction and synchrotron radiation have been used as radiation sources and as measurement device a Martin-Puplett interferometer. In the frame of this thesis data have been taken using pyroelectric detectors, DTGS detectors, Golay cells and bolometers. An analysis procedure for the data has been developed and thoroughly tested including among other things the correction of the frequency dependence of the different sources and diffraction effects inside the interferometer. It is possible to reconstruct asymmetric charge distributions using the dispersion relation by Kramers and Kronig. It could be shown, that the analysis is able to reconstruct the expected charge distributions as long as the detectors are not limited in their low frequency acceptance. Depending on the actual amount of noise on the measured data different shapes and widths can be reconstructed with errors below 10% and can hence be distinguished. The results show only small dependencies on the bunch compression parameters, while the shapes and widths are in good agreement with other results. The shortest bunch length measured has a full width at half maximum of approximately 1.6 ps. (orig.)

  10. Integration of energy-efficient empty fruit bunch drying with gasification/combined cycle systems

    International Nuclear Information System (INIS)

    Highlights: • Novel integrated drying, gasification and combined cycle for empty fruit bunch. • Application of enhanced process integration to achieve high total energy efficiency. • The technology covers exergy recovery and process integration. • High overall energy efficiency can be achieved (about 44% including drying). - Abstract: A high-energy-efficient process for empty fruit bunch drying with integration to gasification and combined cycle processes is proposed. The enhancement is due to greater exergy recovery and more efficient process integration. Basically, the energy/heat involved in a single process is recovered as much as possible, leading to minimization of exergy destruction. In addition, the unrecoverable energy/heat is utilized for other processes through process integration. During drying, a fluidized bed dryer with superheated steam is used as the main evaporator. Exergy recovery is performed through exergy elevation via compression and effective heat coupling in a dryer and heat exchangers. The dried empty fruit bunches are gasified in a fluidized bed gasifier using air as the fluidizing gas. Furthermore, the produced syngas is utilized as fuel in the combined cycle module. From process analysis, the proposed integrated processes can achieve a relatively high energy efficiency. Compared to a standalone drying process employing exergy recovery, the proposed integrated drying can reduce consumed energy by about 1/3. In addition, the overall integrated processes can reach a total power generation efficiency of about 44%

  11. Proposal of An Experiment on Bunch Length Modulation in DAFNE

    International Nuclear Information System (INIS)

    Obtaining very short bunches is an issue especially for colliders but also for CSR sources. The modulation of the bunch length in a strong rf focusing regime had been proposed, corresponding to a high value of the synchrotron tune. A ring structure where the function R56 along the ring oscillates between large positive and negative values will produce bunch length modulation. The synchrotron frequency can be tuned both by the rf power and by the integral of the function R56, up to the limit of zero value corresponding to the isochronicity condition. The proposal of a bunch length modulation along the ring in DAΦNE is here described. DAΦNE lattice can be tuned to positive or negative momentum compaction values, or to structures in which the two arcs are respectively set to positive/negative integrals of the R56 function. With the installation of an extra rf system at 1.3 GHz, experiments on bunch length modulation both in the regime of high and low synchrotron tune can be realized

  12. Coherent diffraction radiation interferometry and short bunch length measurements

    International Nuclear Information System (INIS)

    The promising approach to measure a length of subpicosecond electron bunch is connected with measurements of coherent diffraction radiation (CDR) spectra due to strong dependence of the spectrum shape on the bunch length σz in the wavelength region λ ∼ σz [Proceedings of the International Symposium on New Visions in Laser-Beam Interactions, Nucl. Instr. and Meth. A 455 (1) (2000)]. The spectral measurements may be carried out by using an interferometer or a polychromator. The alternative approach for similar measurements is proposed in the paper. The interference pattern from two shifted halves of a CDR target may be used for this aim. If the broadband detector measures a CDR yield around λ0 ∼ σz then moving one half of the CDR target relative to other (parallel to beam) in the range of a few bunch lengths one can obtain the detuning curve (interferogram). The shape of detuning curve and its connection with bunch length is calculated for different detector apertures and detector waveband. The proposed technique may open the new possibility for non-invasive bunch length measurements in the subpicosecond range

  13. Electron Bunch Shape Measurements Using Electro-optical Spectral Decoding

    Science.gov (United States)

    Borysenko, A.; Hiller, N.; Müller, A.-S.; Steffen, B.; Peier, P.; Ivanisenko, Y.; Ischebeck, R.; Schlott, V.

    Longitudinal diagnostics of the electron bunch shapes play a crucial role in the operation of linac-based light sources. Electro-optical techniques allow us to measure the longitudinal electron bunch profiles non-destructively on a shot-by-shot basis. Here we present results from measurements of electron bunches with a length of 200-900 fs rms at the Swiss FEL Injector Test Facility. All the measurements were done using an Yb-doped fibre laser system (with a central wavelength of a 1050 nm) and a GaP crystal. The technique of electro-optical spectral decoding (EOSD) was applied and showed great capabilities to measure bunch shapes down to around 370 fs rms. Measurements were performed for different electron energies to study the expected distortions of the measured bunch profile due to the energy-dependent widening of the electric field, which plays a role for low beam energies below and around 40 MeV. The studies provide valuable input for the design of the EOSD monitors for the compact linear accelerator FLUTE that is currently under commissioning at the Karslruhe Institute of Technology (KIT).

  14. Harmonically resonant cavity as a bunch-length monitor

    Science.gov (United States)

    Roberts, B.; Hannon, F.; Ali, M. M.; Forman, E.; Grames, J.; Kazimi, R.; Moore, W.; Pablo, M.; Poelker, M.; Sanchez, A.; Speirs, D.

    2016-05-01

    A compact, harmonically resonant cavity with fundamental resonant frequency 1497 MHz was used to evaluate the temporal characteristics of electron bunches produced by a 130 kV dc high voltage spin-polarized photoelectron source at the Continuous Electron Beam Accelerator Facility (CEBAF) photoinjector, delivered at 249.5 and 499 MHz repetition rates and ranging in width from 45 to 150 picoseconds (FWHM). A cavity antenna attached directly to a sampling oscilloscope detected the electron bunches as they passed through the cavity bore with a sensitivity of ˜1 mV /μ A . The oscilloscope waveforms are a superposition of the harmonic modes excited by the beam, with each cavity mode representing a term of the Fourier series of the electron bunch train. Relatively straightforward post-processing of the waveforms provided a near-real time representation of the electron bunches revealing bunch-length and the relative phasing of interleaved beams. The noninvasive measurements from the harmonically resonant cavity were compared to measurements obtained using an invasive RF-deflector-cavity technique and to predictions from particle tracking simulations.

  15. Emittance-dominated long bunches in dual harmonic RF system

    Institute of Scientific and Technical Information of China (English)

    AN Shi-Zhong; Klaus Bongardt; Rudolf Maier; TANG Jing-Yu; ZHANG Tian-Jue

    2008-01-01

    The storage of long bunches for long time intervals needs flattened stationary buckets with a large bucket height. The longitudinal motion of the initially mismatched beam has been studied for both the single and dual harmonic RF systems. The RF amplitude is determined to be r.m.s wise matched. The bucket height of the single harmonic system is too small even for shorter bunch with only 20% increased energy spread. The Halo formation and even debunching can be seen after a few synchrotron periods for single particles with large amplitude. In the case of small energy spread for a cooled beam, Coulomb interaction cannot be ignored. The external voltage has to be increased to keep the r.m.s bunch length unchanged. The new voltage ratio R(N) simplifies physics for the emittance-dominated bunches with modest particle number N. For the single harmonic system, substantial amount of debunching occurs without increasing the external voltage, but very little if the RF amplitude is doubled. Results from the ORBIT tracking code are presented for the 1 GeV bunch in the HESR synchrotron, part of the GSI FAIR project.

  16. Performance of the transverse coupled-bunch feedback system in the SRRC

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, K.T.; Kuo, C.C.; Kuo, C.H.; Lin, K.K.; Ueng, T.S.; Weng, W.T.

    1996-10-01

    A transverse feedback system has been implemented and commissioned in the SRRC storage ring to suppress transverse coupled-bunch oscillations of the electron beam. The system includes transverse oscillation detectors, notch filter, baseband quadrature processing circuitry, power amplifiers, and kickers. To control a large number of transverse coupled-bunch modes, the system is broad-band, bunch-by- bunch in nature. Because the system is capable of bunch-by-bunch correction, it can also be useful for suppressing instabilities introduced by ions. The sextupole strength was then reduced to improve dynamic aperture and hence lifetime of the storage ring.

  17. Modulated Electron Bunch with Amplitude Front Tilt in an Undulator

    CERN Document Server

    Geloni, Gianluca; Saldin, Evgeni

    2015-01-01

    In a previous paper we discussed the physics of a microbunched electron beam kicked by the dipole field of a corrector magnet by describing the kinematics of coherent undulator radiation after the kick. We demonstrated that the effect of aberration of light supplies the basis for understanding phenomena like the deflection of coherent undulator radiation by a dipole magnet. We illustrated this fact by examining the operation of an XFEL under the steady state assumption, that is a harmonic time dependence. We argued that in this particular case the microbunch front tilt has no objective meaning; in other words, there is no experiment that can discriminate whether an electron beam is endowed with a microbunch front tilt of not. In this paper we extend our considerations to time-dependent phenomena related with a finite electron bunch duration, or SASE mode of operation. We focus our attention on the spatiotemporal distortions of an X-ray pulse. Spatiotemporal coupling arises naturally in coherent undulator radi...

  18. Bunching high intensity proton beams with a CH-DTL

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, Malte; Claessens, Christine; Heilmann, Manuel; Hinrichs, Ole; Koser, Daniel; Meusel, Oliver; Noll, Daniel; Podlech, Holger; Ratzinger, Ulrich; Seibel, Anja [Institut fuer Angewandte Physik, Goethe-Universitaet Frankfurt am Main (Germany)

    2014-07-01

    The Frankfurt Neutron Source at the Stern-Gerlach-Zentrum (FRANZ) will provide ultra short neutron pulses at high intensities and repetition rates. The facility is under construction with an expected first beam by the end of 2014. A 5-Gap CH rebuncher is installed behind a coupled RFQ/IH-DTL combination at the end of the LINAC section between two magnetic quadrupole triplets. It will be used for varying the final energy between 1.8 and 2.2 MeV, as well as for focusing the proton beam bunch longitudinally, to compensate RF defocusing effects and huge space charge forces at currents up to 200 mA at the final stage of extension. Therefore high current beam dynamic simulations are in progress. They include benchmarking of different beam dynamic codes like LORASR, TraceWin and Bender (a new PIC tracking code developed at IAP), as well as validating the results by measurements. Detailed error tolerance studies, thermal simulations and examination of multipole field impact, due to the cavity geometry, are also done. Furthermore, this CH rebuncher serves as prototype for CH cavity operation at MYRRHA (Belgium), an Accelerator Driven System (ADS) for transmutation of high level nuclear waste. After copper-plating the cavity, RF conditioning will start in spring 2014.

  19. Bunching high intensity proton beams with a CH-DTL

    International Nuclear Information System (INIS)

    The Frankfurt Neutron Source at the Stern-Gerlach-Zentrum (FRANZ) will provide ultra short neutron pulses at high intensities and repetition rates. The facility is under construction with an expected first beam by the end of 2014. A 5-Gap CH rebuncher is installed behind a coupled RFQ/IH-DTL combination at the end of the LINAC section between two magnetic quadrupole triplets. It will be used for varying the final energy between 1.8 and 2.2 MeV, as well as for focusing the proton beam bunch longitudinally, to compensate RF defocusing effects and huge space charge forces at currents up to 200 mA at the final stage of extension. Therefore high current beam dynamic simulations are in progress. They include benchmarking of different beam dynamic codes like LORASR, TraceWin and Bender (a new PIC tracking code developed at IAP), as well as validating the results by measurements. Detailed error tolerance studies, thermal simulations and examination of multipole field impact, due to the cavity geometry, are also done. Furthermore, this CH rebuncher serves as prototype for CH cavity operation at MYRRHA (Belgium), an Accelerator Driven System (ADS) for transmutation of high level nuclear waste. After copper-plating the cavity, RF conditioning will start in spring 2014.

  20. Fermented empty fruit bunch (FEFB) as feed for ruminant animal

    International Nuclear Information System (INIS)

    Fermented oil palm empty fruit bunch, now known as 'Sterifeed' has been characterized by physico-chemical properties. It has also been proven to have an improved digestibility (by in vitro and in-vivo test) over the original material. The remaining important aspect of feed to be examined is the long term effect of feeding this material to animals. The size of fermentation media bags used was 0.5 - 1 kg/bag. In the large scale production of these materials, the numbers of bags were increased. The production at pilot scale level reinvestigated the basic processing parameters for the 1 kg/bag media and also performed a trial run for different sizes of bags. These include: 1) investigation on the growth of fungi on fermentation media subjected to different treatment times and the non treated media, 2) evaluation of the processing rate, 3) trial run processing of 25-50 MT oil palm EFB into feed, and 4) processing of different sizes of bags