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Sample records for bunching

  1. 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)

  2. 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

  3. 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)

  4. 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)

  5. 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

  6. 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)

  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. 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.

  9. 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.

  10. 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...

  11. 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

  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. 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)

  15. 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.

  16. 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

  17. 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)

  18. 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

  19. 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

  20. 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.

  1. 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)

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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...

  8. 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.

  9. 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...

  10. 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

  11. 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

  12. 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.

  13. 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

  14. 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

  15. 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)

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. 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...

  4. 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.

  5. 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

  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. 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

  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. 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.

  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. 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).

  14. 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).

  15. 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)

  16. 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.

  17. 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.

  18. 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)

  19. 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.

  20. 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.

  1. 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

  2. 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...

  3. 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

  4. 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)

  5. 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)

  6. 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.

  7. 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

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.)

  14. 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.

  15. 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...

  16. 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

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 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

  7. 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

  8. 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.

  9. 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.

  10. 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

  11. 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

  12. 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.}

  13. 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

  14. 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.

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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...

  1. 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.

  2. ''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)

  3. 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...

  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. 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

  6. 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)

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. 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)

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. 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.

  20. 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...

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. 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

  6. 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

  7. 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.

  8. 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

  9. 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

  10. 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

  11. 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

  12. 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)

  13. 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

  14. 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

  15. 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.

  16. 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)

  17. 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

  18. 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.

  19. 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)

  20. 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

  1. 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.

  2. 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.)

  3. 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.

  4. 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.

  5. 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

  6. 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].

  7. 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).

  8. 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

  9. 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...

  10. 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...

  11. 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.

  12. 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...

  13. 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...

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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.)

  19. 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...

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. 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....

  5. 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

  6. 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

  7. 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

  8. 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...

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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)

  14. 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...

  15. 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

  16. 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.

  17. 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...

  18. 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.

  19. 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

  20. 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

  1. 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

  2. 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.

  3. 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

  4. 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

  5. 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...

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. 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

  19. 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

  20. 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.

  1. 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...

  2. 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

  3. 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.

  4. 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...

  5. 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

  6. 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 ...

  7. 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.

  8. 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

  9. 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.

  10. 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...

  11. 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...

  12. 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

  13. 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.

  14. 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

  15. 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

  16. 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).

  17. 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.

  18. 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.

  19. 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.

  20. 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...

  1. 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.

  2. 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.

  3. Bunch gap signal picking-up in BEPC II

    International Nuclear Information System (INIS)

    A high speed circuit is designed for obtaining the BEPC II bunch fiducial signal based on tunnel diode circuit, monostable multivibrator and ECL logic technology. The bunch train with a gap in storage ring is described. The waveforms of the induced signal of the pickup electrode after long cable transmission decay are analyzed. A monostable multivibrator using tunnel diode is described, with which a positive pulse of 0.3 ns is stretched to a 4 ns ECL signal. The ways to find out gap in standard and non-standard injection mode are presented. The test result shows that the circuit works well in standard and non-standard bunch injection modes and the measured timing jitter of 80.49 ps(RMS) fits for the design. (authors)

  4. Commissioning of the LCLS Linac and Bunch Compressors

    International Nuclear Information System (INIS)

    The Linac Coherent Light Source (LCLS) is a SASE x-ray Free-Electron Laser (FEL) project under construction at SLAC [1]. The injector section, from drive-laser and RF photocathode gun through the first bunch compressor, was commissioned in the spring and summer of 2007. The second phase of commissioning, including the second bunch compressor and various main linac modifications, was completed in January through August of 2008. We report here on experience gained during this second phase of machine commissioning, including the injector, the first and second bunch compressor stages, the linac up to 14 GeV, and beam stability measurements. The final commissioning phase, including the undulator and the long transport line from the linac, is set to begin in December 2008, with first light expected in July 2009

  5. Chicane and wiggler based bunch compressors for future linear colliders

    International Nuclear Information System (INIS)

    In this paper, the authors 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, the authors describe bunch compressors based upon magnetic chicanes or wigglers which do not 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, they present a detailed design for the NLC linear collider

  6. A waveguide overloaded cavity as longitudinal kicker for the DA{Phi}NE bunch-by-bunch feedback system

    Energy Technology Data Exchange (ETDEWEB)

    Gallo, A.; Boni, R.; Ghigo, A.; Marcellini, F.; Serio, M.; Zobov, M. [Instituto Nazionale de Fisica Nucleare, Frascati (Italy). Lab. Nazionale di Frascati

    1996-08-01

    The multibunch operation of DA{Phi}NE calls for a very efficient feedback system to damp the coupled-bunch longitudinal instabilities. A collaboration program among SLAC, LBL and LNF laboratories on this subject led to the development of a time domain, digital system based on digital signal processors that has been already successfully tested at ALS. The feedback chain ends with the longitudinal kicker, an electromagnetic structure capable of transferring the proper energy correction to each bunch. A cavity kicker for the DA{Phi}NE bunch-by-bunch longitudinal feedback system based on a pill-box loaded by six waveguides has been designed and a full-scale aluminium prototype has been fabricated at LNF. Both simulations and measurements have shown a peak shunt impedance of about 750 ohm and a bandwidth of about 220 MHz. The large shunt impedance allows to economize on the costly feedback power. Moreover, the damping waveguides drastically reduce the device HOM longitudinal and transverse impedances. One cavity pre ring will be sufficient to operate the machine up to 30 bunches while a second device per ring together with a feedback power improvement will be necessary to reach the ultimate current. (G.T.)

  7. Design of the Source Development Lab bunch compressor

    International Nuclear Information System (INIS)

    The accelerator at the Source Development Lab at BNL consists of a 1.6 cell RF photocathode electron gun followed by a 230 MeV SLAC-type linac that includes a magnetic chicane bunch compressor. The nominal specifications call for a 10 ps FWHM bunch of 2nC charge to be compressed in time by a factor of 25 at an energy of 85 MeV. The design of the compressor magnets and the beam dynamics from the gun through the magnetic chicane are described

  8. 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.

  9. The First Results of Bunch Shape Measurements in SNS Linac

    CERN Document Server

    Feschenko, A; Kisselev, Yu V; Kravchuk, L V; Liyu, A; Menshov, A; Mirzojan, A N

    2004-01-01

    Three Bunch Shape Monitors with transverse scanning of low energy secondary electrons for the SNS Linac have been developed and fabricated. The peculiarity of the detectors is using of energy separation of the electrons. The separation enables to minimize influence of detached electrons originated from dissociation of H-minus ions in the detector wire target. The first detector was used at the exit of the first DTL tank during its commissioning. The results of Bunch Shape measurements are presented and discussed. These results were used to verify beam quality, to set parameters of the accelerating field, to estimate a longitudinal beam halo and to restore a longitudinal beam emittance.

  10. Measuring the longitudinal bunch profile at CTF3

    CERN Document Server

    Dabrowski, A E; Bettoni, S; Braun†, H H; Corsini, R; Döbert, S; Egger, D; Lefevre, T; Rabiller, A; Shaker, H; Soby, L; Skowronski, P K; Tecker, F; Velasco, M

    2010-01-01

    The CLIC Test Facility 3 (CTF3) is being built and commissioned by an international collaboration in order to test the feasibility of the proposed Compact Linear Collider (CLIC) two-beam acceleration scheme. The monitoring and control of the bunch length throughout the CTF3 complex is important since this affects the efficiency and the stability of the final RF power production process. Bunch length diagnostics therefore form an essential component of the beam instrumentation at CTF3. This paper presents longitudinal profile measurements based on Streak camera and non-destructive RF power and microwave spectrometry techniques.

  11. Optical plasma torch electron bunch generation in plasma wakefield accelerators

    Science.gov (United States)

    Wittig, G.; Karger, O.; Knetsch, A.; Xi, Y.; Deng, A.; Rosenzweig, J. B.; Bruhwiler, D. L.; Smith, J.; Manahan, G. G.; Sheng, Z.-M.; Jaroszynski, D. A.; Hidding, B.

    2015-08-01

    A novel, flexible method of witness electron bunch generation in plasma wakefield accelerators is described. A quasistationary plasma region is ignited by a focused laser pulse prior to the arrival of the plasma wave. This localized, shapeable optical plasma torch causes a strong distortion of the plasma blowout during passage of the electron driver bunch, leading to collective alteration of plasma electron trajectories and to controlled injection. This optically steered injection is more flexible and faster when compared to hydrodynamically controlled gas density transition injection methods.

  12. Bunch Length Measurements With Laser/SR Cross-Correlation

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Timothy; /Stanford U., Phys. Dept.; Daranciang, Dan; /Stanford U., Phys. Dept.; Lindenberg, Aaron; /Stanford U., Phys. Dept.; Corbett, Jeff; /SLAC; Fisher, Alan; /SLAC; Goodfellow, John; /SLAC; Huang, Xiaobiao; /SLAC; Mok, Walter; /SLAC; Safranek, James; /SLAC; Wen, Haidan; /SLAC

    2012-07-06

    By operating SPEAR3 in low-{alpha} mode the storage ring can generate synchrotron radiation pulses of order 1ps. Applications include pump-probe x-ray science and the production of THz radiation in the CSR regime. Measurements of the bunch length are difficult, however, because the light intensity is low and streak cameras typically provide resolution of only a few ps. Tests are now underway to resolve the short bunch length using cross-correlation between a 60-fs Ti:Sapphire laser and the visible SR beam in a BBO crystal. In this paper we report on the experimental setup, preliminary measurements and prospects for further improvement.

  13. The Optimized Bunch Compressor for the International Linear Collider

    International Nuclear Information System (INIS)

    The International Linear Collider (ILC) utilizes a two stage Bunch Compressor (BC) that compresses the RMS bunch length from 9 mm to 200 to 300 micrometers before sending the electron beam to the Main Linac. This paper reports on the new design of the optimized BC wiggler. It was reduced in length by more than 30%. The introduction of nonzero dispersion slope in the BC wigglers enabled them to generate the required compression while having a small SR emittance growth, a tunability range of over a factor of 2 in each wiggler, and less than 3% RMS energy spread throughout the entire system

  14. VISCOSITY ANALYSIS OF EMPTY FRUIT BUNCH (EFB) BIO-OIL

    OpenAIRE

    Z.S. Nazirah; M.J.M. Ridzuan; S.M. Hafis; Mohamed, A R; K.Azduwin

    2013-01-01

    Empty fruit bunches (EFB) are one of the solid wastes produced by the palm oil industry, which is increasing rapidly. The aim of this paper is to analyse the viscosity of empty fruit bunch (EFB) bio-oil that can be extracted from all solid waste EFB as a sample, and a few processes were executed. The samples underwent two processes, which were pre-treatment and pyrolysis. The pre-treatment involved three processes, namely, cutting, shredding and sieving, which were necessary in order to prepa...

  15. Operation and performance of bunch pre-compression for increased transmission at the SLC

    International Nuclear Information System (INIS)

    As the beam currents at the SLC are increased, transverse aperture restrictions in the ring-to-linac transport line (RTL) become increasingly important. The RTL contains a bunch compressor which introduces a large energy variation across the bunch and hence a larger transverse beam size. Since 1994 the compressor amplitude has been operating at higher than design voltage. While advantageous for shaping the bunch distribution, this increased the bunch energy spread and therefore resulted in more beam loss. Moreover, due to current-dependent bunch lengthening in the damping ring, the higher the beam current, the more the current loss. To avoid such losses, the bunch length may be precompressed in the damping ring. Until recently, bunch precompression with high beam currents was not stable. In this paper the authors identify the reasons for the difficulties, describe the changes made to accommodate bunch precompression, and discuss performance aspects after implementation. The estimated increase in current at the interaction point is 15%

  16. A betatron tune measurement system based on bunch-by-bunch transverse feedback at the Duke storage ring

    Science.gov (United States)

    Xu, Wei; Z. Wu, W.; Li, Jing-Yi; He, Duo-Hui; K. Wu, Y.

    2013-07-01

    To combat electron beam instabilities, a digital bunch-by-bunch transverse feedback (TFB) system has been developed for the Duke storage ring. While it is capable of suppressing transverse beam instabilities for multibunch operation, the TFB system has not been needed for typical operation of the Duke storage ring. To explore the great potential of this system, we have developed beam diagnostic techniques using the TFB, in particular, the TFB based tune measurement techniques. The tune measurement technique allows us to conduct fast chromaticity measurements, compared with the existing chromaticity measurement system using a network analyzer. This new tune measurement system also enables us to measure the bunch tune for multibunch operation of the Duke storage ring. With the TFB based tune measurement system, we have studied the tune stability of the electron beam in the Duke storage ring. This tune system has also been used to calibrate the tune knob for the Duke storage ring.

  17. Bunch-shape monitor for a picosecond single-bunch beam of a 35 MeV electron linear accelerator

    International Nuclear Information System (INIS)

    A non-interactive-type bunch-shape and beam intensity monitor for a 35 MeV electron linear accelerator (linac) has been developed. The monitor consists of an electric SMA-type connector and an Al pipe of 50 mm inner diameter. Test measurements of the present monitor have been made under the conditions of the accelerated charges of lower than 27 nC/pulse and the pulse width ranging from 6 to 30 ps (Full Width at Half Maximum). The results show that the present monitor is applicable to bunch-shape measurement of the picosecond single-bunch beam. The monitor output is also found to be proportional to the beam intensity of more than 0.05 nC/pulse. (author)

  18. Bunch-Shape Monitor for a Picosecond Single-Bunch Beam of a 35 MeV Electron Linear Accelerator

    Science.gov (United States)

    Hosono, Yoneichi; Nakazawa, Masaharu; Iguchi, Tetsuo; Ueda, Touru; Kobayashi, Tosiaki; Kozawa, Takahiro; Uesaka, Mitsuru; Ohkuma, Juzo; Okuda, Shuichi; Yamamoto, Tamotsu; Suemine, Shoji

    1995-09-01

    A non-interactive-type bunch-shape and beam intensity monitor for a 35 MeV electron linear accelerator (linac) has been developed. The monitor consists of an electric SMA-type connector and an Al pipe of 50 mm inner diameter. Test measurements of the present monitor have been made under the conditions of the accelerated charges of lower than 27 nC/pulse and the pulse width ranging from 6 to 30 ps (Full Width at Half Maximum). The results show that the present monitor is applicable to bunch-shape measurement of the picosecond single-bunch beam. The monitor output is also found to be proportional to the beam intensity of more than 0.05 nC/pulse.

  19. Observation of the substructure in the electron bunch on the ACO storage ring

    International Nuclear Information System (INIS)

    In the future, one interesting point of the SRFEL at Orsay will be the microtemporal analysis of the laser beam correlated with that of the electron bunch. In a first time, we have only analysed the temporal structure of the electron bunch with an Electrophotonic streak camera. The first results seem to indicate that the bunch is not an homogeneous bunch but presents a substructure. We discuss with details this data

  20. Excitation of wake waves in plasma by a succession of charged particle bunches. II

    International Nuclear Information System (INIS)

    The problem of excitation of wake waves in plasma by a succession of homogeneous relativistic electron bunches is considered. A recurrent relation between the amplitude of wake fields of the n-th and (n-1)-th bunches has been obtained. It was shown that the maximum possible value of the amplitude of wake field in case of a single bunches may by obtained behind the N-th bunch, when nb/na>1. 11 refs

  1. Design of a multi-bunch BPM for the next linear collider

    International Nuclear Information System (INIS)

    The Next Linear Collider (NLC) will collide 180-bunch trains of electrons and positrons with bunch spacing of 1.4 ns. The small spot size (σy < 3 nm) at the interaction point requires precise control of emittance, which in turn requires the alignment of individual bunches in the train to within a fraction of a micron. Multi-bunch beam position monitors (BPMs) are to determine the bunch-to-bunch misalignment on each machine pulse. High bandwidth kickers will then be programmed to bring the train into better alignment on the next machine cycle. A prototype multi-bunch BPM system with bandwidth (350 MHz) sufficient to distinguish adjacent bunches has been built at SLAC. It is based on 5 G sample/s digitization of analog sum and difference channels. Calibration tone injection and logging of the single bunch impulse response provide the kernel for deconvolution of bunch-by-bunch position from the sum and difference waveforms. These multi-bunch BPMs have been tested in the Accelerator Test Facility at KEK and in the PEP-II ring at SLAC. The results of these measurements are presented in this paper

  2. An Electron Bunch Compressor Based on an FEL Interaction in the Far Infra Red

    CERN Document Server

    Gaupp, Andreas

    2013-01-01

    In this note an electron bunch compressor is proposed based on FEL type interaction of the electron bunch with far infrared (FIR) radiation. This mechanism maintains phase space density and thus requires a high quality electron beam to produce bunches of the length of a few ten micrometer.

  3. Short Electron Beam Bunch Characterization Through Measurement of Terahertz Radiation

    CERN Document Server

    Zhang, Shukui; Douglas, David; Shinn, Michelle D; Williams, Gwyn

    2004-01-01

    Characterization of the electron beam bunch length of the upgrade FEL at Jefferson Lab was performed by analyzing the FTIR spectra of the coherent terahertz pulses. The results are compared with autocorrelation from a scanning polarization autocorrelator that measures the optical transition radiation. The limitations of the different methods to such a characterization are presented in this paper.

  4. Plasmas in particle accelerators: adiabatic theories for bunched beams

    International Nuclear Information System (INIS)

    Three different formalisms for discussing Vlasov's equation for bunched beam problems with anharmonic space charge forces are outlined. These correspond to the use of a drift kinetic equation averaged over random betatron motions; a fluidkinetic adiabatic regime analogous to the theory of Chew, Goldberger, and Low; and an adiabatic hydrodynamic theory

  5. The stability of ions in bunched-beam machines

    International Nuclear Information System (INIS)

    In this paper, the conditions leading to the accumulation of ions are established for various cases of bunched beams, together with the maximum ion density which can be reached. An application to the SPS panti p collider is also given. (orig./HSI)

  6. LHC Report: 1,033 bunches per beam and counting

    CERN Multimedia

    Jorg Wenninger for the LHC team

    2015-01-01

    Following the second technical stop, the first beams were injected into the LHC in the early evening of Saturday, 5 September. About ten days later, the machine was operated with around 1,000 bunches per beam.    Evolution of the stored energy per LHC beam, over time.   The first step after a technical stop consists of running through a full LHC cycle, from injection to collisions and beam dump, with a low-intensity bunch (“probe”) to check all machine settings and equipment. This is followed by a series of collimation and absorber validation tests at different points in the LHC cycle. Low-intensity beams – typically the equivalent of three nominal bunches (3 x 1011 protons) – are expanded transversely or longitudinally, or de-bunched to verify that the collimators and absorbers are correctly intercepting lost particles. The techniques for those validations have been progressively improved, and t...

  7. Scanning Synchronization of Colliding Bunches for MEIC Project

    Energy Technology Data Exchange (ETDEWEB)

    Derbenev, Yaroslav S. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Popov, V. P. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Chernousov, Yu D. [Inst. of Chemical Kinetics and Combustion, Novosibirsk (Russian Federation); Kazakevich, G. M. [Euclid Techlabs LLC., Cleveland, OH (United States)

    2015-09-01

    Synchronization of colliding beams is one of the major issues of an electron-ion collider (EIC) design because of sensitivity of ion revolution frequency to beam energy. A conventional solution for this trouble is insertion of bent chicanes in the arcs space. In our report we consider a method to provide space coincidence of encountering bunches in the crab-crossing orbits Interaction Region (IR) while repetition rates of two beams do not coincide. The method utilizes pair of fast kickers realizing a bypass for the electron bunches as the way to equalize positions of the colliding bunches at the Interaction Point (IP). A dipole-mode warm or SRF cavities fed by the magnetron transmitters are used as fast kickers, allowing a broad-band phase and amplitude control. The proposed scanning synchronization method implies stabilization of luminosity at a maximum via a feedback loop. This synchronization method is evaluated as perspective for the Medium Energy Electron-Ion collider (MEIC) project of JLab with its very high bunch repetition rate.

  8. Test of new diagnostics for bunch length measurement

    International Nuclear Information System (INIS)

    Two new diagnostics for bunch length measurements have been recently tested at the ESRF. The first one is based on the spectral analysis of the visible light beam produced by a dipole. The beam is collimated at the input of a photodiode whose output is connected to a spectrum analyzer. The frequency signature is then equivalent to the longitudinal spectrum of the beam. The second device is based on two HF cavities, tuned at two different frequencies, and coupled to the beam wake fields. Their response to the beam passage gives the component of the beam spectrum at the two specified frequencies, from which the beam profile may be reconstructed. Results for these two devices will be presented and compared to measurements made with a streak camera in order to evaluate them. In the low current per bunch regime, both devices show promising results as the theoretical value for zero current bunch length could be reproduced. In this regime, the microwave cavity offers a faster acquisition time. Unfortunately, for high current bunches, time reconstruction is no longer possible for both devices, because the Gaussian approximation is no longer valid. The spectrum method accurately describes, the evolution of the longitudinal spectrum with current, but absolute values will differ by about 20% from the streak camera measurements

  9. Instability of a witness bunch in a plasma bubble

    CERN Document Server

    Burov, A; Nagaitsev, S

    2016-01-01

    The stability of a trailing witness bunch, accelerated by a plasma wake accelerator (PWA) in a blow-out regime, is discussed. The instability growth rate as well as the energy spread, required for BNS damping, are obtained. A relationship between the PWA power efficiency and the BNS energy spread is derived.

  10. 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

  11. Study of Short Bunches at the Free Electron Laser CLIO

    CERN Document Server

    Delerue, Nicolas; Khodnevych, Vitalii; Berthet, Jean-Paul; Glotin, Francois; Ortega, Jean-Michel; Prazeres, Rui

    2016-01-01

    CLIO is a Free Electron Laser based on a thermionic electron gun. In its normal operating mode it delivers electron 8 pulses but studies are ongoing to shorten the pulses to about 1 ps. We report on simulations showing how the pulse can be shortened and the expected signal yield from several bunch length diagnostics (Coherent Transition Radiation, Coherent Smith Purcell Radiation).

  12. Instability of a witness bunch in a plasma bubble

    Energy Technology Data Exchange (ETDEWEB)

    Burov, A. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Lebedev, V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Nagaitsev, S. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2016-02-16

    The stability of a trailing witness bunch, accelerated by a plasma wake accelerator (PWA) in a blow-out regime, is discussed. The instability growth rate as well as the energy spread, required for BNS damping, are obtained. A relationship between the PWA power efficiency and the BNS energy spread is derived.

  13. 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

  14. BUNCHED BEAM STOCHASTIC COOLING SIMULAITONS AND COMPARISON WITH DATA

    Energy Technology Data Exchange (ETDEWEB)

    BLASKIEWICZ,M.; BRENNAN, J.M.

    2007-09-10

    With the experimental success of longitudinal, bunched beam stochastic cooling in RHIC it is natural to ask whether the system works as well as it might and whether upgrades or new systems are warranted. A computer code, very similar to those used for multi-particle coherent instability simulations, has been written and is being used to address these questions.

  15. Electro-optic methods for longitudinal bunch diagnostics at FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Steffen, B.R.

    2007-07-15

    Precise measurements of the temporal profile of sub-picosecond electron bunches are of high interest for the optimization and operation of VUV and X-ray free electron lasers. In this thesis, the shortest electro-optic signals measured so far for electron bunch diagnostics are presented, reaching a time resolution of better than 50 fs (rms). The e ects that introduce signal distortions and limit the time resolution are studied in numerical simulations for different electro-optic detection materials and techniques. The time resolution is mainly limited by lattice resonances of the electro-optic crystal. Electro-optic signals as short as 54 fs (rms) are obtained with gallium phosphide (GaP) crystals in a crossed polarizer detection scheme using temporally resolved electro-optic detection. Measuring near crossed polarization, where the electro-optic signal is proportional to the velocity field of the relativistic electron bunch, the shortest obtained signal width is 70 fs (rms). The electro-optic signals are compared to electron bunch shapes that are measured simultaneously with a transverse deflecting structure with 20 fs resolution. Numerical simulations using the bunch shapes as determined with the transverse deflecting cavity as input data are in excellent agreement with electro-optical signals obtained with GaP, both for temporally and spectrally resolved measurements. In the case of zinc telluride (ZnTe) the observed signals are slightly broader and significantly smaller than expected from simulations. These discrepancies are probably due to the poor optical quality of the available ZnTe crystals. (orig.)

  16. Measuring the electron bunch timing with femtosecond resolution at FLASH

    International Nuclear Information System (INIS)

    Bunch arrival time monitors (BAMs) are an integral part of the laser-based synchronisation system which is being developed at the Free Electron Laser in Hamburg (FLASH).The operation principle comprises the measurement of the electron bunch arrival time relative to the optical timing reference, which is provided by actively length-stabilised fibre-links of the synchronisation system. The monitors are foreseen to be used as a standard diagnostic tool, not only for FLASH but also for the future European X-Ray Free-Electron Laser (European XFEL). The present bunch arrival time monitors have evolved from proof-of-principle experiments to beneficial diagnostic devices, which are almost permanently available during standard machine operation. This achievement has been a major objective of this thesis. The developments went in parallel to improvements in the reliable and low-maintenance operation of the optical synchronisation system. The key topics of this thesis comprised the characterisation and optimisation of the opto-mechanical front-ends of both, the fibre-links and the BAMs. The extent of applications involving the bunch arrival time information has been enlarged, providing automated measurements for properties of the RF acceleration modules, for instance, the RF on-crest phase determination and the measurement of energy fluctuations. Furthermore, two of the currently installed BAMs are implemented in an active phase and gradient stabilisation of specific modules in order to minimise the arrival time jitter of the electron bunches at the location of the FEL undulators, which is crucial for a high timing resolution of pump-probe experiments.

  17. Electro-optic methods for longitudinal bunch diagnostics at FLASH

    International Nuclear Information System (INIS)

    Precise measurements of the temporal profile of sub-picosecond electron bunches are of high interest for the optimization and operation of VUV and X-ray free electron lasers. In this thesis, the shortest electro-optic signals measured so far for electron bunch diagnostics are presented, reaching a time resolution of better than 50 fs (rms). The e ects that introduce signal distortions and limit the time resolution are studied in numerical simulations for different electro-optic detection materials and techniques. The time resolution is mainly limited by lattice resonances of the electro-optic crystal. Electro-optic signals as short as 54 fs (rms) are obtained with gallium phosphide (GaP) crystals in a crossed polarizer detection scheme using temporally resolved electro-optic detection. Measuring near crossed polarization, where the electro-optic signal is proportional to the velocity field of the relativistic electron bunch, the shortest obtained signal width is 70 fs (rms). The electro-optic signals are compared to electron bunch shapes that are measured simultaneously with a transverse deflecting structure with 20 fs resolution. Numerical simulations using the bunch shapes as determined with the transverse deflecting cavity as input data are in excellent agreement with electro-optical signals obtained with GaP, both for temporally and spectrally resolved measurements. In the case of zinc telluride (ZnTe) the observed signals are slightly broader and significantly smaller than expected from simulations. These discrepancies are probably due to the poor optical quality of the available ZnTe crystals. (orig.)

  18. Measuring the electron bunch timing with femtosecond resolution at FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Bock, Marie Kristin

    2013-03-15

    Bunch arrival time monitors (BAMs) are an integral part of the laser-based synchronisation system which is being developed at the Free Electron Laser in Hamburg (FLASH).The operation principle comprises the measurement of the electron bunch arrival time relative to the optical timing reference, which is provided by actively length-stabilised fibre-links of the synchronisation system. The monitors are foreseen to be used as a standard diagnostic tool, not only for FLASH but also for the future European X-Ray Free-Electron Laser (European XFEL). The present bunch arrival time monitors have evolved from proof-of-principle experiments to beneficial diagnostic devices, which are almost permanently available during standard machine operation. This achievement has been a major objective of this thesis. The developments went in parallel to improvements in the reliable and low-maintenance operation of the optical synchronisation system. The key topics of this thesis comprised the characterisation and optimisation of the opto-mechanical front-ends of both, the fibre-links and the BAMs. The extent of applications involving the bunch arrival time information has been enlarged, providing automated measurements for properties of the RF acceleration modules, for instance, the RF on-crest phase determination and the measurement of energy fluctuations. Furthermore, two of the currently installed BAMs are implemented in an active phase and gradient stabilisation of specific modules in order to minimise the arrival time jitter of the electron bunches at the location of the FEL undulators, which is crucial for a high timing resolution of pump-probe experiments.

  19. 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

  20. 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.

  1. Bunching of a low-velocity ion beam and the development of beam diagnostic technology

    International Nuclear Information System (INIS)

    An RF cavity resonator for bunching the low-velocity ions has been installed in the beam line from an ECR ion source on a test stand, and the bunch structure is observed by a Faraday cup with good frequency response characteristics. This test stand is originally for development of beam monitors. Owing to the introduction of the RF cavity, beam monitors for bunched beam observation can be tested. Reversely beam bunching characteristics of cavities can be examined on this test stand. Measurements of H, O and Ar beams bunched by an RF cavity equipped with a magnetic alloy are reported. The design of the Faraday cup is also described. (K. Yoshida)

  2. A fifth harmonic rf bunch monitor for the ANL-APS electron linac

    International Nuclear Information System (INIS)

    The function of a fifth harmonic (14.28 GHz) bunch monitor is to provide a signal which is proportional to the electron beam bunch size. The monitoring of the rf power signal at 14.28 GHz enables the operator to optimize the rf bunching of the beam at the end of the first accelerating section where the full bunching has been formed and remains mainly constant in size throughout the rest of the electron linac. A modified version of the SLAC original bunch monitor has been fabricated and its rf properties measured. This paper describes the design and the initial measurement results

  3. Self-pinching of a relativistic electron bunch in a drift tube

    OpenAIRE

    Parazzoli, Claudio G.; Koltenbah, Benjamin E. C.

    1997-01-01

    Electron bunches with charge densities $\\rho$ of the order of $10^2$ to $10^3$ [nC/cm$^3$], energies between $20.$ and $100.$ [MeV], peak current $>100$ [A], bunch lengths between 0.3 and 1.8 [cm], and bunch charge of 2.0 to $20.$ [nC] are relevant to the design of Free Electron Lasers and future linear colliders. In this paper we present the results of numerical simulations performed with a particle in a cell (pic) code of an electron bunch in a drift tube. The electron bunch has cylindrical...

  4. Experimental Characterization of Sub-picosecond Electron Bunch Length with Coherent Diffraction Radiation

    International Nuclear Information System (INIS)

    Diffraction radiation is one of the most promising candidates for electron beam diagnostics for the International Linear Collider, x-ray free electron lasers and energy recovery linac due to its non-intercepting characteristics. We report the non-intercepting measurement of sub-ps electron bunch length with coherent diffraction radiation. The bunch length is measured with a Martin—Puplett interferometer and the detailed longitudinal bunch shape is reconstructed with the Kramers—Kronig relation. The rms bunch length is found to be about 0.73 ps, which confirms a successful commissioning of the bunch compressor and the interferometer. (nuclear physics)

  5. Experimental characterization of sub-picosecond electron bunch length with coherent diffraction radiation

    International Nuclear Information System (INIS)

    Diffraction radiation is one of the most promising candidates for electron beam diagnostics for the International Linear Collider, x-ray free electron lasers and energy recovery linac due to its non-intercepting characteristics. We report the non-intercepting measurement of sub-ps electron bunch length with coherent diffraction radiation. The bunch length is measured with a Martin-Puplett interferometer and the detailed longitudinal bunch shape is reconstructed with the Kramers-Kronig relation. The rms bunch length is found to be about 0.73 ps, which confirms a successful commissioning of the bunch compressor and the interferometer. (authors)

  6. Exploiting coherence for real-time studies by single-bunch imaging

    OpenAIRE

    Rack, A; Scheel, M; Hardy, L; Curfs, C.; Bonnin, A; Reichert, H

    2014-01-01

    First real-time studies of ultra-fast processes by single-bunch imaging at the European Synchrotron Radiation Facility are reported. By operating the storage ring of the ESRF in single-bunch mode with its correspondingly increased electron bunch charge density per singlet, the polychromatic photon flux density at insertion-device beamlines is sufficient to capture hard X-ray images exploiting the light from a single bunch (the corresponding bunch length is 140 ps FWHM). Hard X-ray imaging wit...

  7. Generation of femtosecond electron bunches using a laser photocathode RF gun linac

    International Nuclear Information System (INIS)

    Electron beams with pulse durations of picoseconds and femtoseconds have been applied to the accelerator physics application such as free electron lasers and laser-Comptom x-rays. The ultrashort electron bunches are also key element in time-resolved measurements including pulse radiolysis to improve the time resolution of the measurements. In this study, femtosecond electron bunches were generated using a laser photocathode RF gun linac and a magnetic bunch compressor at ISIR, Osaka University. The bunch lengths were evaluated by detecting coherent transition radiation (CTR) emitted from the electron bunches using a Michelson interferometer. (author)

  8. Estimation of emittance degradation due to multi-pole fields of XFEL bunch compressors

    International Nuclear Information System (INIS)

    In order to obtain a high-brightness electron beam in an XFEL, the electron bunch should be longitudinally compressed in a linear accelerator using magnetic bunch compressors composed of four bending magnets. The bunch compression requires a large energy chirp on the electron bunch, which produces a horizontal spread of the beam size inside bunch compressors. Since the bending magnets have multi-pole field components, they leak energy-dispersion and degrade emittance downstream of the chicane. In this paper, the emittance degradation due to the multi-pole fields of the bending magnets is estimated using simplified analytical formulae for the XFEL/SPring-8. (author)

  9. 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)

  10. Ponderomotive scattering of an electron-bunch before injection into a laser wakefield

    CERN Document Server

    Khachatrian, A G; Luttikhof, M J H; Van Goor, F A

    2006-01-01

    For the purpose of laser wakefield acceleration, it turned out that also the injection of electron bunches longer than a plasma wavelength can generate accelerated femtosecond bunches with relatively low energy spread. This is of high interest because such injecting bunches can be provided, e.g., by state-of-the-art photo cathode RF guns. Here we point out that when an e-bunch is injected in the wakefield it is important to take into account the ponderomotive scattering of the injecting bunch by the laser pulse in the vacuum region located in front of the plasma. At low energies of the injected bunch this scattering results in a significant drop of the collection efficiency. Larger collection efficiency can by reached with lower intensity laser pulses and relatively high injection energies. We also estimate the minimum trapping energy for the injected electrons and the length of the trapped bunch.

  11. Creation and Storage of Long and Flat Bunches in the LHC

    CERN Document Server

    Damerau, H

    2005-01-01

    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 400.8MHz, long and flat bunches held by multiples of 40.08MHz, 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 com...

  12. 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

  13. 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

  14. 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.

  15. A compact source for bunches of singly charged atomic ions

    Science.gov (United States)

    Murböck, T.; Schmidt, S.; Andelkovic, Z.; Birkl, G.; Nörtershäuser, W.; Vogel, M.

    2016-04-01

    We have built, operated, and characterized a compact ion source for low-energy bunches of singly charged atomic ions in a vacuum beam line. It is based on atomic evaporation from an electrically heated oven and ionization by electron impact from a heated filament inside a grid-based ionization volume. An adjacent electrode arrangement is used for ion extraction and focusing by applying positive high-voltage pulses to the grid. The method is particularly suited for experimental environments which require low electromagnetic noise. It has proven simple yet reliable and has been used to produce μs-bunches of up to 106 Mg+ ions at a repetition rate of 1 Hz. We present the concept, setup and characterizing measurements. The instrument has been operated in the framework of the SpecTrap experiment at the HITRAP facility at GSI/FAIR to provide Mg+ ions for sympathetic cooling of highly charged ions by laser-cooled 24Mg+.

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

    International Nuclear Information System (INIS)

    In this paper, two possible bunch compression configurations are proposed and evaluated by numerical simulation in the Next Linear Collider Test Accelerator (NLCTA) at SLAC. A bunch compression ratio up to 20 could be achieved under a perfect condition, without consideration for the timing jitter and other error sources. The NLCTA is a test accelerator built at SLAC, which is approximately 42 meters long and composed of X-band acceleration structures. The main aim of building NLCTA is to develop and demonstrate the X-band rf acceleration technologies for the next generation linear collider, with a relatively high acceleration gradient between 50 MV/m and 100 MV/m. The current operation configuration of NLCTA features a thermionic-cathode electron gun at its starting point which generates an electron beam with an energy of 5 MeV. This is followed by a roughly 1.5 meter long X-band acceleration structure which boosts the electron beam energy to 60 MeV. Then there is a four-dipole magnetic chicane which is 6 meters long and provides a first order longitudinal dispersion of R56 = -73mm. Next the electron beam passes by several matching quadrupoles and can be accelerated further to 120 MeV through another one-meter-long X-band acceleration structure. After that, there are three small chicanes downstream, with a total first order longitudinal dispersion of R56 = -10mm. A sketch of the main components of NLCTA is shown in Figure 1, where the total length of this accelerator is 45 meters. Free Electron Lasers (FELs), proposed by J. Madey and demonstrated for the first time at Stanford University in 1970s (2) (3), use the lasing of relativistic electron beam traveling through a magnetic undulator, which can reach high power and can be widely tunable in wavelength. Linac based FEL source can provide sufficient brightness, and a short X-ray wavelength down to angstrom scale, which promises in supporting wide range of research experiments. In order to have an electron beam

  17. MD210 Note: Creation of Hollow Bunches in the PSB

    CERN Document Server

    Oeftiger, Adrian; Findlay, Alan James; Hancock, Steven; Rumolo, Giovanni; CERN. Geneva. ATS Department

    2016-01-01

    MD210 aims for the creation of longitudinally hollow bunches in the CERN PS Booster. The first three sessions have been carried out using the radial loop feedback system in order to drive the beam on a dipolar parametric resonance (instead of the phase loop). It has been found that the damping by the phase loop inhibits the excitation of the resonance to a major extent. The hollow distributions generated under these circumstances fail to reach a satisfying bunching factor. Nonetheless, proving the principally successful application of this technique to the PS Booster promises good results once the phase loop system supports trim functions. The approach, actions and detailed results of the first three MD sessions are presented in this paper.

  18. 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

  19. Bunch Shape Monitors For The Desy H-Minus Linac

    Science.gov (United States)

    Feschenko, A. V.; Liiou, A. V.; Mirzojan, A. N.; Menshov, A. A.; Ostroumov, P. N.; Holtkamp, N.; Nagl, M.; Peperkorn, I.

    1997-05-01

    In order to tune and control the longitudinal bunch shape and energy spread in the DESY Proton linac (LINAC III), three Bunch Shape Monitors (BSM) have been developed and installed. The mechanical layout has been optimised in order to fit the extremely narrow space between the DTL tanks. One of the BSMs, as an additional feature, can measure the absolute energy of the beam and is installed downstream of three Alvarez tanks. Using of thin wire as a source of secondary electrons, these devices can be used as a non-destructive beam diagnostic tool during Linac operation. The performance of the BSMs as well as the results of the Linac III studies using the new devices will be presented.

  20. Bunch-motion feedback for B-factories

    International Nuclear Information System (INIS)

    The colliding electron and positron beams in a B-factory must have average current of one ampere or more to produce the required luminosity. The high current interacts with structures in the beam tube to drive strong coupled-bunch (c.b.) instabilities. To suppress these instabilities requires negative feedback of the bunch motions. Beam impedances arising from strong rf cavity modes should first be reduced to make the required feedback damping rate practical and the cost economical. In what follows, control of transverse motions will be discussed first, then longitudinal. We shall use the parameters of the 3.1 GeV ring of PEP-II to illustrate the general requirements

  1. 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)

  2. Biperiodical bunching system based on the evanescent waves

    CERN Document Server

    Ayzatsky, M I; Perezhogin, S A

    2001-01-01

    To improve the beam bunching at the initial stage of acceleration it is necessary to create an increasing field distribution. Such distribution can be created in a biperiodic disk-loaded waveguide. It is well known that in periodic structures there are two different types of electromagnetic oscillations. In the passbands they exist in the form of travelling waves.In the stopbands electromagnetic oscillations exist in the form of evanescent waves and have the decreasing (increasing) dependence on the coordinate. The properties of electromagnetic oscillations in the stopband that exists in the biperiodic structure due to its biperiodicity are investigated. The results of the simulation of bunching process in the system based on the evanescent wave are presented.

  3. 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.

  4. 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.

  5. 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.

  6. 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)

  7. Universality of Generalized Bunching and Efficient Assessment of Boson Sampling

    Science.gov (United States)

    Shchesnovich, V. S.

    2016-03-01

    It is found that identical bosons (fermions) show a generalized bunching (antibunching) property in linear networks: the absolute maximum (minimum) of the probability that all N input particles are detected in a subset of K output modes of any nontrivial linear M -mode network is attained only by completely indistinguishable bosons (fermions). For fermions K is arbitrary; for bosons it is either (i) arbitrary for only classically correlated bosons or (ii) satisfies K ≥N (or K =1 ) for arbitrary input states of N particles. The generalized bunching allows us to certify in a polynomial in N number of runs that a physical device realizing boson sampling with an arbitrary network operates in the regime of full quantum coherence compatible only with completely indistinguishable bosons. The protocol needs only polynomial classical computations for the standard boson sampling, whereas an analytic formula is available for the scattershot version.

  8. Generation of ultrashort electron bunches by colliding laser pulses

    International Nuclear Information System (INIS)

    A proposed laser-plasma based relativistic electron source [E. Esarey et al., Phys. Rev. Lett. 79, 2682 (1997)] using laser triggered injection of electrons is investigated. The source generates ultrashort electron bunches by dephasing and trapping background plasma electrons undergoing fluid oscillations in an excited plasma wake. The plasma electrons are dephased by colliding two counter-propagating laser pulses which generate a slow phase velocity beat wave. Laser pulse intensity thresholds for trapping and the optimal wake phase for injection are calculated. Numerical simulations of test particles, with prescribed plasma and laser fields, are used to verify analytic predictions and to study the longitudinal and transverse dynamics of the trapped plasma electrons. Simulations indicate that the colliding laser pulse injection scheme has the capability to produce relativistic femtosecond electron bunches with fractional energy spread of order a few percent and normalized transverse emittance less than 1 mm mrad using 1 TW injection laser pulses

  9. Repetitive Bunches from RF-Photo Gun Radiate Coherently

    CERN Document Server

    Van der Geer, C A J; Van der Geer, S B

    2004-01-01

    We consider to feed the laser wake field accelerator of the alpha-X project by a train of low charge pancake electron bunches to reduce undesired expansion due to space-charge forces. To this purpose the photo excitation laser of the rf-injector is split into a train of sub-pulses, such that each of the produced electron bunches falls into a successive ponderomotive well of the plasma accelerator. This way the total accelerated charge is not reduced. The repetitive photo gun can be tested, at low energy, by connecting it directly to the undulator and monitoring the radiation. The assertions are based on the results of new GPT simulations.

  10. 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.

  11. Measurement of electron beam bunch phase length by rectangular cavities

    International Nuclear Information System (INIS)

    An analysis of a phase length of electron bunches with the help of crossed rectangular resonators with the Hsub(102) oscillation type has been made. It has been shown that the electron coordinates after the duplex resonator are described by an ellipse equation for a non-modulated beam. An influence of the initial energy spread upon the electron motion has been studied. It has been ascertained that energy modulation of the electron beam results in displacement of each electron with respect to the ellipse which is proportional to modulation energy, i.e. an error in determination of the phase length of an electron bunch is proportional to the beam energy spread. Relations have been obtained which enable to find genuine values of phases of the analyzed electrons with an accuracy up to linear multipliers

  12. Absolute Bunch Length Measurements by Incoherent Radiation Fluctuation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sannibale, F.; /LBL, Berkeley; Stupakov, G.V.; /SLAC; Zolotorev, M.S.; /LBL, Berkeley; Filippetto, D.; /INFN, Rome; Jagerhofer, L.; /Vienna, Tech. U.

    2009-12-09

    By analyzing the pulse to pulse intensity fluctuations of the radiation emitted by a charge particle in the incoherent part of the spectrum, it is possible to extract information about the spatial distribution of the beam. At the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory, we have developed and successfully tested a simple scheme based on this principle that allows for the absolute measurement of the rms bunch length. A description of the method and the experimental results are presented.

  13. 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.

  14. Bunch lengthening with bifurcation in electron storage rings

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Eun-San; Hirata, Kohji [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

    1996-08-01

    The mapping which shows equilibrium particle distribution in synchrotron phase space for electron storage rings is discussed with respect to some localized constant wake function based on the Gaussian approximation. This mapping shows multi-periodic states as well as double bifurcation in dynamical states of the equilibrium bunch length. When moving around parameter space, the system shows a transition/bifurcation which is not always reversible. These results derived by mapping are confirmed by multiparticle tracking. (author)

  15. 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.

  16. 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

  17. Longitudinal bunch compression study with induction voltage modulator

    OpenAIRE

    Nakayama Akira; Sakai Yasuo; Miyazaki Yoshifumi; Kikuchi Takashi; Nakajima Mitsuo; Horioka Kazuhiko

    2013-01-01

    For the beam driver of inertial confinement fusion, the technology to compress a charged particle beam in longitudinal direction is crucially important. However, the quality of the beam is expected to be deteriorated when the beam is rapidly compressed in longitudinal direction. In order to investigate the beam dynamics during bunch compression, we made a compact beam compression system and carried out beam compression experiments. In this paper, we show the background of our study and recent...

  18. 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.

  19. 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....

  20. 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)

  1. 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.

  2. LHC Report: Boost in bunches brings record luminosity

    CERN Multimedia

    2011-01-01

    Having hit a luminosity of around 8.4x1032 cm-2 s-1 with 768 bunches per beam, the LHC went into a 5-day machine development (MD) program on Wednesday 4 May. Operators are now working on increasing the number of particle bunches in the machine towards a 2011 maximum of around 1380 bunches. The team is already hitting major milestones, recording another record-breaking peak luminosity on Monday 23 May.   Former LHC Project Leader Lyn Evans (to the right) and Laurette Ponce, the engineer-in-charge when the recent luminosity record was achieved. The MD periods improve our understanding of the machine, with the aim of increasing its short- and long-term performance. This one also included tests of the machine’s configurations for special physics runs and a future high luminosity LHC. It was an intense program and overall it went very well, with most measurements carried out successfully. Highlights included: commissioning a dedicated machine setup for TOTEM and ALFA; succe...

  3. 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.

  4. Bunch shape measurement of CW heavy-ion beam

    International Nuclear Information System (INIS)

    An accurate bunch shape measurement is one of the most important tasks during the fine tuning of multi-cavity accelerators. A device for the measurement of bunch time structure of cw heavy-ion beams with time resolution ∼20 picoseconds was developed, constructed and commissioned at ATLAS which is a 50 MV superconducting heavy-ion linac. The Bunch Shape Monitor (BSM) is based on the analysis of secondary electrons produced by a primary beam hitting a tungsten wire to which a potential of -10 kV is applied. In a BSM the longitudinal distribution of charge of the primary beam is coherently transformed into a spatial distribution of low energy secondary electrons through transverse rf modulation. The distribution of secondary electrons is detected by a chevron MCP coupled to a phosphor screen. The signal image on the screen is measured by use of a CCD camera connected to a PC. This BSM analyzes cw beams rather than pulsed beams studied by a previous device [1]. Design features of the BSM and the beam measurement results are reported

  5. Stability of Flat Bunches in the Recycler Barrier Bucket

    Energy Technology Data Exchange (ETDEWEB)

    Sen, T.; Bhat, C.; Ostiguy, J.-F.; /Fermilab

    2009-05-01

    We examine the stability of intense flat bunches in barrier buckets used in the Fermilab Recycler. We consider some common stationary distributions and show that they would be unstable against rigid dipole oscillations. We discuss the measurements which identify stable distributions. We also report on experimental studies on the impact of creating a local extremum of the incoherent frequency within the rf bucket. We considered two typical stationary distributions and found they were not adequate descriptions of the Recycler bunches. From the measured line density distribution we find (a) the tanh function is a good fit to the line density, and (b) the coherent frequency of the rigid dipole mode for this distribution is within the incoherent spread at nominal intensities. Stability diagrams when the beam couples to space charge and external impedances will be discussed elsewhere. Our initial experimental investigations indicate that longitudinal stability in the Recycler is, consistent with expectations, influenced by the ratio T{sub 2}/(4T{sub 1}) which determines the location of the extremum of the incoherent tune. The coherent tune depends strongly on the distribution in the bunch tails which is difficult to measure. Numerical studies using both a conventional tracking code and a Vlasov solver are in progress and should provide more insight into conditions that may lead to unstable behavior.

  6. Characterization of pseudosingle bunch kick-and-cancel operational mode

    Science.gov (United States)

    Sun, C.; Robin, D. S.; Steier, C.; Portmann, G.

    2015-12-01

    Pseudosingle-bunch kick-and-cancel (PSB-KAC) is a new operational mode at the Advanced Light Source of Lawrence Berkeley National Laboratory that provides full timing and repetition rate control for single x-ray pulse users while being fully transparent to other users of synchrotron radiation light. In this operational mode, a single electron bunch is periodically displaced from a main bunch train by a fast kicker magnet with a user-on-demand repetition rate, creating a single x-ray pulse to be matched to a typical laser excitation pulse rate. This operational mode can significantly improve the signal to noise ratio of single x-ray pulse experiments and drastically reduce dose-induced sample damage rate. It greatly expands the capabilities of synchrotron light sources to carry out dynamics and time-of-flight experiments. In this paper, we carry out extensive characterizations of this PSB-KAC mode both numerically and experimentally. This includes the working principle of this mode, resonance conditions and beam stability, experimental setups, and diagnostic tools and measurements.

  7. 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

  8. Emittance control and RF bunch compression in the NSRRC photoinjector

    Science.gov (United States)

    Lau, W. K.; Hung, S. B.; Lee, A. P.; Chou, C. S.; Huang, N. Y.

    2011-05-01

    The high-brightness photoinjector being constructed at the National Synchrotron Radiation Research Center is for testing new accelerator and light-source concepts. It is the so-called split photoinjector configuration in which a short solenoid magnet is used for emittance compensation. The UV-drive laser pulses are also shaped to produce uniform cylindrical bunches for further reduction of beam emittance. However, limited by the available power from our microwave power system, the nominal accelerating gradient in the S-band booster linac is set at 18 MV/m. A simulation study with PARMELA shows that the linac operating at this gradient fails to freeze the electron beam emittance at low value. A background solenoid magnetic field is applied for beam emittance control in the linac during acceleration. A satisfactory result that meets our preliminary goal has been achieved with the solenoid magnetic field strength at 0.1 T. RF bunch compression as a means to achieve the required beam brightness for high-gain free-electron laser experiments is also examined. The reduction of bunch length to a few hundred femtoseconds can be obtained.

  9. Emittance control and RF bunch compression in the NSRRC photoinjector

    International Nuclear Information System (INIS)

    The high-brightness photoinjector being constructed at the National Synchrotron Radiation Research Center is for testing new accelerator and light-source concepts. It is the so-called split photoinjector configuration in which a short solenoid magnet is used for emittance compensation. The UV-drive laser pulses are also shaped to produce uniform cylindrical bunches for further reduction of beam emittance. However, limited by the available power from our microwave power system, the nominal accelerating gradient in the S-band booster linac is set at 18 MV/m. A simulation study with PARMELA shows that the linac operating at this gradient fails to freeze the electron beam emittance at low value. A background solenoid magnetic field is applied for beam emittance control in the linac during acceleration. A satisfactory result that meets our preliminary goal has been achieved with the solenoid magnetic field strength at 0.1 T. RF bunch compression as a means to achieve the required beam brightness for high-gain free-electron laser experiments is also examined. The reduction of bunch length to a few hundred femtoseconds can be obtained.

  10. Characterestics of pico-second single bunch at the S-band linear accelerator

    International Nuclear Information System (INIS)

    Measurement of the bunch structure of a pico-second single bunch was performed using a femto-second streak camera at the S-band linear accelerator of the University of Tokyo. The aim of this research is to investigate the feasibility of the generation of a femto-second single bunch at the S-band linac. The details of the bunch structure and energy spectrum of an original single bunch were precisely investigated in several operation modes where the RF phases in accelerating tubes and a prebuncher were varied. The femto-second streak camera was utilized to measure the bunch structure by one shot via Cherenkov radiation emitted by the electrons in the bunch. Next, an experiment for magnetic pulse compression of the original single bunch was carried out. Pulse shapes of the compressed bunchs for different energy modulation were also obtained by measuring Cherenkov radiation by one shot using the femto-second streak camera. Prior to the experiment, numerical tracking analysis to determine operating parameters for the magnetic pulse compression was also done. Measured pulse widths were compared with calculated ones. Finally, a 2 ps (full width at half maximum; FWHM) single bunch with an electric charge of 0.3 nC could be generated by the magnetic pulse compression. ((orig.))

  11. 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.)

  12. 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.)

  13. Design of a Multi-Bunch BPM for the Next Linear Collider

    CERN Document Server

    Young, A

    2001-01-01

    The Next Linear Collider (NLC) design requires precise control of colliding trains of high-intensity (1.4 x 10 sup 1 sup 0 particles/bunch) and low-emittance beams. High-resolution multi-bunch beam position monitors (BPMs) are required to ensure uniformity across the bunch trains with bunch spacing of 1.4ns. A high bandwidth (approx 350 MHz) multi-bunch BPM has been designed based on a custom-made stripline sum and difference hybrid on a Teflon-based material. High bandwidth RF couplers were included to allow injection of a calibration tone. Three prototype BPMs were fabricated at SLAC and tested in the Accelerator Test Facility at KEK and in the PEP-II ring at SLAC. Tone calibration data and single-bunch and multi-bunch beam data were taken with high-speed (5Gsa/s) digitizers. Offline analysis determined the deconvolution of individual bunches in the multi-bunch mode by using the measured single bunch response. The results of these measurements are presented in this paper.

  14. 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.

  15. Coherent Smith-Purcell radiation as a diagnostic for sub-picosecond electron bunch length

    International Nuclear Information System (INIS)

    We suggest a novel technique of measuring sub-picosecond electron bunch length base on coherent Smith-Purcell radiation (SPR) emitted when electrons pass close to the surface of a metal grating. With electron bunch lengths comparable to the grating period, we predict that coherent SPR will be emitted at large angles with respect to direction of beam propagation. As the bunch length shortens, the coherent SPR will be enhanced over the incoherent component that is normally observed at small angles. Furthermore, the angular distribution of the coherent SPR will be shifted toward smaller angles as the bunch length becomes much smaller than the grating period. By measuring the angular distribution of the coherent SPR, one can determine the bunch length of sub-picosecond electron pulses. This new technique is easy to implement and appears capable of measuring femtosecond electron bunch lengths

  16. Preliminary calculations of ballistic bunch compression with thermionic cathode rf guns

    International Nuclear Information System (INIS)

    Preliminary calculations using the computer code PARMELA indicate that it is possible to achieve peak currents on the order of 1 kA using a thermionic-cathode rf gun and ballistic bunch compression. In contrast to traditional magnetic bunching schemes, ballistic bunch compression uses a series of rf cavities to modify the energy profile of the beam and properly chosen drifts to allow the bunching to occur naturally. The method, suitably modified, should also be directly applicable to photoinjector rf guns. Present work is focusing on simultaneously compressing the bunch while reducing the emittance of the electron beam. At present, the calculated normalized rms emittance is in the neighborhood of 6.8 π mm mrad with a peak current of 0.88 kA, and a peak bunch charge of 0.28 nC from a thermionic-cathode gun

  17. 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

  18. Evaluation of electron bunch shapes using the spectra of the coherent radiation

    CERN Document Server

    Nakamura, M; Okuda, S; Kozawa, T; Kato, R; Takahashi, T; Nam, S K

    2001-01-01

    The bunch shape of single-bunch electron beams, generated with a 38 MeV L-band linear accelerator, was evaluated using the longitudinal bunch form factor at the Institute of Scientific and Industrial Research at Osaka University. The single-bunch beams are being used in experiments for generating self-amplified spontaneous emission and coherent radiation. In the present experiments, the energy of the electron beam was 27 MeV, the energy spread 1.1% FWHM, and the electron charge in a bunch 13.5 nC. The form factor was obtained from the spectrum of the coherent transition radiation measured with a Martin-Pupplet interferometer. A streak measurement was also performed in the same configurations and the results were compared to those for the measurements of the coherent radiation. By using these two methods, the performance of a chicane-type bunch compressor was investigated.

  19. 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)

  20. Electromagnetic field excitation by an electron bunches in a partially filled cylindrical dielectric resonator

    International Nuclear Information System (INIS)

    A nonlinear self-consistent theory of wakefield excitation by an electron bunches in cylindrical resonator with longitudinally nonuniform filling by dielectric is constructed. A bunch-excited field are presented in the form of superposition solenoidal and potential fields. The formulated nonlinear theory allows carrying out numerical analysis of resonator excitation by electron bunches for the best interpretation of the results received in experiment

  1. 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)

  2. Application of coherent synchrotron radiation to the bunch length monitor for JLC

    International Nuclear Information System (INIS)

    The complete spectrum of coherent synchrotron radiation were measured at wavelengths from 0.16 to 3.5 mm. A bunch shape was estimated by the Fourier analysis for this spectrum. This result agree with that of simulation for the bunching process in the injector of the accelerator. These properties of coherent synchrotron radiation can be applied to the bunch length monitor for JLC. (author)

  3. Bunch length measurements using a Martin-Puplett interferometer at the VUV-FEL

    International Nuclear Information System (INIS)

    In this thesis, the results of longitudinal bunch shape and bunch length measurements at the DESY VUV-FEL are discussed. As short electron bunches are required for a high-gain free electron laser, the coherent synchrotron radiation (CSR) they produce in a magnetic chicane can be used for diagnostics. The employment of a Martin-Puplett interferometer for measuring the CSR spectrum and the principle of reconstructing the charge distribution from it are presented. (orig.)

  4. 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.

  5. 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...

  6. The design of an electron gun grid pulse circuit for a single bunch mode operation

    International Nuclear Information System (INIS)

    Siam Photon Source (Thailand) operates multiple bunch system at Booster. For the single bunch mode operation, the electron gun will emit a bunch of electron at pulse width 4 ns. A gun grid circuit is designed by using a pulse forming network and an avalanche technique. The circuit is tested with a high bandwidth oscilloscope and the circuit is then connected to the gun assembly.

  7. 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)...

  8. Electro-optic measurement of the wake fields of 16 MeV electron bunches

    International Nuclear Information System (INIS)

    The authors demonstrate the measurement in the time domain and with picosecond resolution of the high frequency electromagnetic fields generated by a bunched beam of 16 MeV electrons. A birefringent crystal placed 2 cm from the beam is sampled in time by a pulsed laser synchronized with the electron bunch. The electric field waveform has been recorded with substantial structure as late as 2.5 ns after the passage of the bunch

  9. 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)

  10. End-to-end simulation of bunch merging for a muon collider

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Yu [Univ. of California, Riverside, CA (United States); Stratakis, Diktys [Brookhaven National Lab. (BNL), Upton, NY (United States); Hanson, Gail G. [Univ. of California, Riverside, CA (United States); Palmer, Robert B. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-05-03

    Muon accelerator beams are commonly produced indirectly through pion decay by interaction of a charged particle beam with a target. Efficient muon capture requires the muons to be first phase-rotated by rf cavities into a train of 21 bunches with much reduced energy spread. Since luminosity is proportional to the square of the number of muons per bunch, it is crucial for a Muon Collider to use relatively few bunches with many muons per bunch. In this paper we will describe a bunch merging scheme that should achieve this goal. We present for the first time a complete end-to-end simulation of a 6D bunch merger for a Muon Collider. The 21 bunches arising from the phase-rotator, after some initial cooling, are merged in longitudinal phase space into seven bunches, which then go through seven paths with different lengths and reach the final collecting "funnel" at the same time. The final single bunch has a transverse and a longitudinal emittance that matches well with the subsequent 6D rectilinear cooling scheme.

  11. High-brightness double-bunch electron beam generation at ISIR

    International Nuclear Information System (INIS)

    A new gun pulser of a 38 MeV L-band linac has been developed to generate a high-brightness double-bunch beam at ISIR. The charge of a bunch is 19 nC and the interval between the two bunches is 37 ns, which is settled with a delay line. The energies of the two bunches are different under ordinary conditions and agree after controlling the conditions of the rf components of the linac. The former beam is applied to developing a new pulse-radiolysis method and the latter to FEL experiments. (author)

  12. 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

  13. 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).

  14. Longitudinal Bunch Shape Monitor Using the Beam Chopper of the J-PARC

    CERN Document Server

    Naito, F

    2004-01-01

    We propose the longitudinal bunch shape monitor for the low energy part of the linac of the J-PARC. The monitor uses the beam chopper cavity installled in the MEBT line between thr RFQ and the DTL of the J-PARC as a kind of the bunch rotator. Consequentry the longitudinal bunch shape is measured along the horizontal direction. If we can measure the energy distribution of the bunch also, the longitudinal emittance of the beam is derived. In the paper, the basic idea of the monitor is discussed in detail.

  15. Measurement of the longitudinal wakefield and the bunch shape in the SLAC linac

    International Nuclear Information System (INIS)

    The authors report on measurements of the bunch energy spectrum at the end of the SLAC linac. Using the spectra obtained for two different linac rf phases they obtain both the bunch induced voltage and the longitudinal distribution of the bunch. The measurement results are compared with theoretical predictions. In particular, the induced voltage is in good agreement with that obtained using the calculated wake function for the SLAC linac. This measurement technique may be useful for monitoring changes of the linac bunch shape in the SLC

  16. 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.

  17. Strong wakefields generated by a train of femtosecond bunches in a planar dielectric microstructure

    Science.gov (United States)

    Wang, Changbiao; Hirshfield, J. L.; Fang, J.-M.; Marshall, Thomas C.

    2004-05-01

    A tall, dielectric-lined rectangular wakefield microstructure is analyzed as a possible element of an advanced linear wakefield accelerator. This accelerator would be driven by a train of fs electron microbunches that would be chopped out of a longer bunch using a powerful CO2 laser and then formed into a train of rectangular-profile bunches using a quadrupole. The bunches set up a periodic wakefield in the microstructure that can be built up to 400 600 MV/m, for example, using a train of ten 3-fs 1-pC bunches. Two major issues are examined. First, interference is studied using the particle-in-cell code KARAT between transition radiation and Cerenkov wakefield radiation, both set up by the passage of a charge bunch through a dielectric structure of finite length. Of significance is the difference in propagation speeds of transition radiation and Cerenkov radiation (which travels almost at the vacuum light speed c) and the magnitude of the respective fields. Second, stability is examined for drive and accelerated bunches using computations of test particle orbits in the longitudinal and transverse wakefields excited by the drive bunches. It is found that nearly all test electrons in the drive bunches are confined within the structure for a travel distance of 30cm or more, while test electrons located in an accelerated bunch can have stable motion over greater than 30cm without passing through the structure walls.

  18. Bunch of restless vector solitons in a fiber laser with SESAM.

    Science.gov (United States)

    Zhao, L M; Tang, D Y; Zhang, H; Wu, X

    2009-05-11

    We report on the experimental observation of a novel form of vector soliton interaction in a fiber laser mode-locked with SESAM. Several vector solitons bunch in the cavity and move as a unit with the cavity repetition rate. However, inside the bunch the vector solitons make repeatedly contractive and repulsive motions, resembling the contraction and extension of a spring. The number of vector solitons in the bunch is controllable by changing the pump power. In addition, polarization rotation locking and period doubling bifurcation of the vector soliton bunch are also experimentally observed. PMID:19434141

  19. 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.)

  20. 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

  1. Generation and measurement of sub-picosecond electron bunch in photocathode rf gun

    International Nuclear Information System (INIS)

    We consider a scheme to generate a sub-picosecond electron bunch in the photocathode rf gun by improving the acceleration gradient in the gun, suitably tuning the bunch charge, the laser spot size and the acceleration phase, and reducing the growth of transverse emittance by laser shaping. A nondestructive technique is also reported to measure the electron bunch length, by measuring the high-frequency spectrum of wakefield radiation which is caused by the passage of a relativistic electron bunch through a channel surrounded by a dielectric. (authors)

  2. Optimization of a bunch compressor at KEK-ERL test facility

    International Nuclear Information System (INIS)

    To produce high brightness synchrotron radiation generated from an energy recovery linac, it is necessary to shorten the bunch length and reduce the emittance of electron beam. However, the energy loss and the emittance growth caused by a coherent synchrotron radiation (CSR) at a bending section are enormous for the short bunch with a length of a few 10-micro meters especially at a low energy. Therefore the bunch length is compressed gradually in the ARC after accelerating the beam up to the full energy. The beam optics for a bunch compression was optimized to suppress the growth of a transverse emittance and an energy spread. (author)

  3. Measurement of the energy loss of an electron bunch passing in a chicane-type bunch compressor due to the coherent synchrotron radiation

    International Nuclear Information System (INIS)

    The energy loss of an electron beam due to the coherent synchrotron radiation in the components for beam transportation possibly degrades the quality of the beam. In this work the energy loss of an intense single-bunch electron beam passing through a chicane-type bunch compressor has been investigated. The single-bunch beams are being used for self-amplified spontaneous emission experiments in Osaka University. At a beam energy of 27 MeV and the charge of electrons in a bunch of 22 nC the peak shift on the energy spectrum of the beam by 1% and the energy loss of about 0.5% have been observed. In order to evaluate the energy of the coherent synchrotron radiation emitted in the bunch compressor a form factor of the electron bunch has been assumed, according to the results for the measurements of the time profile of the electron bunch with a streak camera and the spectrum of the coherent transition radiation

  4. Measurement of the energy loss of an electron bunch passing in a chicane-type bunch compressor due to the coherent synchrotron radiation

    CERN Document Server

    Okuda, S; Yokoyama, K

    2000-01-01

    The energy loss of an electron beam due to the coherent synchrotron radiation in the components for beam transportation possibly degrades the quality of the beam. In this work the energy loss of an intense single-bunch electron beam passing through a chicane-type bunch compressor has been investigated. The single-bunch beams are being used for self-amplified spontaneous emission experiments in Osaka University. At a beam energy of 27 MeV and the charge of electrons in a bunch of 22 nC the peak shift on the energy spectrum of the beam by 1% and the energy loss of about 0.5% have been observed. In order to evaluate the energy of the coherent synchrotron radiation emitted in the bunch compressor a form factor of the electron bunch has been assumed, according to the results for the measurements of the time profile of the electron bunch with a streak camera and the spectrum of the coherent transition radiation.

  5. 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.

  6. Theory and simulation of CSR microbunching in bunch compressors

    Science.gov (United States)

    Huang, Zhirong; Borland, Michael; Emma, Paul; Kim, Kwang-Je

    2003-07-01

    CSR microbunching instability in bunch compressors is studied both analytically and numerically. The iterative solutions of the integral equation for the instability provide approximate expressions of CSR microbunching due to initial density and energy modulation, and can be applied to a series of bending systems consisting of multiple compressor chicanes and transport lines. Two similar but independent simulation methods are developed and are compared to each other as well as with theory. We determine the total gain in density modulation for all bend systems of the Linac Coherent Light Source and discuss initial conditions that start the unstable process.

  7. Theory and simulation of CSR microbunching in bunch compressors

    International Nuclear Information System (INIS)

    CSR microbunching instability in bunch compressors is studied both analytically and numerically. The iterative solutions of the integral equation for the instability provide approximate expressions of CSR microbunching due to initial density and energy modulation, and can be applied to a series of bending systems consisting of multiple compressor chicanes and transport lines. Two similar but independent simulation methods are developed and are compared to each other as well as with theory. We determine the total gain in density modulation for all bend systems of the Linac Coherent Light Source and discuss initial conditions that start the unstable process

  8. Tool Wear Characteristics of Oil Palm Empty Fruit Bunch Particleboard

    OpenAIRE

    Jegatheswaran Ratnasingam; Tee Chew Tek; Saied Reza Farrokhpayam

    2008-01-01

    A series of machining experiments on the Oil-Palm Empty Fruit Bunch (OPEFB) particleboard were carried out using a CNC router, to evaluate the tool wearing properties of the composite in comparison to the conventional wood-material particleboard. A single-fluted tungsten-carbide router bit (12 mm φ, 18 000 rpm), with a rake angle of 15° was used in this experiment, in which the depth of cut was 1.5 mm and feed speed was 4.5 m min-1. The router bit machined the edge of the board, moving along ...

  9. A BUNCH TO BUCKET PHASE DETECTOR USING DIGITAL RECEIVER TECHNOLOGY.

    Energy Technology Data Exchange (ETDEWEB)

    DELONG,J.; BRENNAN, J. M.; HAYES,T.; TUONG, N. LE,; SMITH, K.

    2003-05-12

    Transferring high-speed digital signals to a Digital Signal Processor is limited by the IO bandwidth of the DSP. A digital receiver circuit is used to translate high frequency W signals to base-band. The translated output frequency is close to DC and the data rate can be reduced, by decimation, before transfer to the DSP. By translating both the longitudinal beam (bunch) and RF cavity pick-ups (bucket) to DC, a DSP can be used to measure their relative phase angle. The result can be used as an error signal in a beam control servo loop and any phase differences can be compensated.

  10. A BUNCH TO BUCKET PHASE DETECTOR USING DIGITAL RECEIVER TECHNOLOGY

    International Nuclear Information System (INIS)

    Transferring high-speed digital signals to a Digital Signal Processor is limited by the IO bandwidth of the DSP. A digital receiver circuit is used to translate high frequency W signals to base-band. The translated output frequency is close to DC and the data rate can be reduced, by decimation, before transfer to the DSP. By translating both the longitudinal beam (bunch) and RF cavity pick-ups (bucket) to DC, a DSP can be used to measure their relative phase angle. The result can be used as an error signal in a beam control servo loop and any phase differences can be compensated

  11. STEAM EXPLOSION PULPING OF OIL PALM EMPTY FRUIT BUNCH FIBER

    OpenAIRE

    Xiwen Wang,; Jian Hu; Jingshan Zeng

    2012-01-01

    Steam explosion pulping was evaluated for oil palm empty fruit bunches fiber. The fiber morphology was observed by SEM and TEM. Results indicated that lignin was molten and the cell wall damaged after the steam explosion pulping and that the fiber was partly separated at the same time. The results of handsheet tests showed that the steam exploded pulp had a high yield (78.2%), good physical properties (especially for ring crush 8.6 N•m/g), and low effluent load (SS=910 mg/L; BOD5=3952 mg/L; C...

  12. Longitudinal bunch compression study with induction voltage modulator

    Directory of Open Access Journals (Sweden)

    Nakayama Akira

    2013-11-01

    Full Text Available For the beam driver of inertial confinement fusion, the technology to compress a charged particle beam in longitudinal direction is crucially important. However, the quality of the beam is expected to be deteriorated when the beam is rapidly compressed in longitudinal direction. In order to investigate the beam dynamics during bunch compression, we made a compact beam compression system and carried out beam compression experiments. In this paper, we show the background of our study and recent progress of the beam compression experiments.

  13. Theory and Simulation of CSR Microbunching in Bunch Compressors

    International Nuclear Information System (INIS)

    CSR microbunching instability in bunch compressors is studied both analytically and numerically. The iterative solutions of the integral equation for the instability provide approximate expressions of CSR microbunching due to initial density and energy modulation, and can be applied to a series of bending systems consisting of multiple compressor chicanes and transport lines. Two similar but independent simulation methods are developed and are compared to each other as well as with theory. We determine the total gain in density modulation for all bend systems of the Linac Coherent Light Source and discuss initial conditions that start the unstable process

  14. The single-mode CSR instability for a bunched beam

    International Nuclear Information System (INIS)

    The coherent synchrotron radiation (CSR) instability at the shielding threshold may be driven by a single synchronous mode excited by the beam in the beam pipe. The instability in this case has been analyzed [1] in the coasting beam approximation neglecting synchrotron motion. The later becomes important at large time intervals in storage rings where it substantially affects the beam dynamics. The single-mode CSR instability of a bunched beam with the synchrotron motion taken into account is described in this paper both in linear and nonlinear regimes. Analysis is relevant to other instabilities where the interaction is dominated by a single mode

  15. Theory and simulation of CSR microbunching in bunch compressors

    International Nuclear Information System (INIS)

    CSR microbunching instability in bunch compressors is studied both analytically and numerically. The iterative solutions of the integral equation for the instability provide approximate expressions of CSR microbunching due to initial density and energy modulation, and can be applied to a series of bending systems consisting of multiple compressor chicanes and transport lines. Two similar but independent simulation methods are developed and are compared to each other as well as with theory. They determine the total gain in density modulation for all bend systems of the Linac Coherent Light Source and discuss initial conditions that start the unstable process

  16. Magnetic Bunch Compression for a Compact Compton Source

    Energy Technology Data Exchange (ETDEWEB)

    Gamage, B. [ODU; Satogata, Todd J. [JLAB

    2013-12-01

    A compact electron accelerator suitable for Compton source applications is in design at the Center for Accelerator Science at Old Dominion University and Jefferson Lab. Here we discuss two options for transverse magnetic bunch compression and final focus, each involving a 4-dipole chicane with M_{56} tunable over a range of 1.5-2.0m with independent tuning of final focus to interaction point $\\beta$*=5mm. One design has no net bending, while the other has net bending of 90 degrees and is suitable for compact corner placement.

  17. 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

  18. 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

  19. Simulation studies of the SLC bunch compressor (RTL)

    Energy Technology Data Exchange (ETDEWEB)

    Zimmermann, F.

    1996-06-01

    In the 1994/95 SLC run, bunch lengthening in the damping ring along with overcompression in the two ring-to-linac transport lines (RTLs) have caused a normal beam loss of about 10-20% between entrance and end of the RTLs, which constitutes a major hindrance to further luminosity increases of the SLC. This paper summarizes studies of both longitudinal and six-dimensional dynamics in the RTL, and compares simulation results with measurements. Quadratic dependence of path length on energy and higher-order multipoles in the RTL quadrupoles are shown to affect the compressor performance. Minor optics changes are suggested which may improve the transmission efficiency.

  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. Overview of coupled bunch active damper systems at FNAL

    International Nuclear Information System (INIS)

    Beam intensities in all of the accelerators at Fermilab will increase significantly when the Main Injector becomes operational and will cause unstable oscillations in transverse position and energy. Places where the coupled bunch oscillations could dilute emittances include the Booster, Main Injector, and Tevatron. This paper provides an overview of the active feedback system upgrades which will be used to counteract the problem. It will explain the similarities between all the systems and will also explain design differences between longitudinal and transverse systems, fast sweeping systems, and systems for partially filled machines. Results from operational systems will also be shown. 7 refs., 4 figs., 1 tab

  2. 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

  3. 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.

  4. Mechanical Properties of Oil Palm Empty Fruit Bunch Fiber

    Science.gov (United States)

    Gunawan, Fergyanto E.; Homma, Hiroomi; Brodjonegoro, Satryo S.; Hudin, Afzer Bin Baseri; Zainuddin, Aryanti Binti

    In tropical countries such as Indonesia and Malaysia, the empty fruit bunches are wastes of the oil palm industry. The wastes are abundantly available and has reached a level that severely threats the environment. Therefore, it is a great need to find useful applications of those waste materials; but firstly, the mechanical properties of the EFB fiber should be quantified. In this work, a small tensile test machine is manufactured, and the tensile test is performed on the EFB fibers. The results show that the strength of the EFB fiber is strongly affected by the fiber diameter; however, the fiber strength is relatively low in comparison to other natural fibers.

  5. Modulation Of Low Energy Beam To Generate Predefined Bunch Trains For The NSLS-II Top-Off Injection

    International Nuclear Information System (INIS)

    The NSLS II linac will produce a bunch train, 80-150 bunches long with 2 ns bunch spacing. Having the ability to tailor the bunch train can lead to the smaller bunch to bunch charge variation in the storage ring. A stripline is planned to integrate into the linac baseline to achieve this tailoring. The stripline must have a fast field rise and fall time to tailor each bunch. The beam dynamics is minimally affected by including the extra space for the stripline. This paper discusses the linac beam dynamics with stripline, and the optimal design of the stripline. A stripline is to be integrated in the linac to match the storage ring uniform bunch charge requirement, which simplifies the gun pulser electronics and looses the edge uniform requirement. It is located at low energy to lower the stripline power supply requirement and limit the dumped electron radiation. By turning off the stripline, the beam dynamics through linac is comparable with the baseline design. More advanced ideas can be explored. If a DC corrector along with the stripline is used, the core bunch trains gets kick from the stripline while the head and the tail of bunch train just gets a DC kick. The stripline power supply waveform is a single flat top waveform with fast rise and drop and the pulse length is ∼200 ns long or 100 bunches, which may be easier from the power supply view point. We are also considering the bunch by bunch charge manipulation to match the storage ring uniform bunch charge distribution requirement. By modulating the flat top waveform at 250 MHz with adjustable amplitude, each the bunch center is either at 45 degree or 135 degree. Only the head or tail of the bunch is trimmed out. Although each bunch center deviation from idea center is very different at low energy, it is gradually minimized with beam energy increase.

  6. DSP and FPGA Based Bunch Current Signal Processing

    CERN Document Server

    Naylor, G A

    2001-01-01

    The current in electron storage rings used as synchrotron light sources must be measured to a very high precision in order to determine the stored beam lifetime. This is especially so in high-energy machines in which the lifetime may be very high. Parametric current transformers (PCT) have traditionally been used to measure the DC or average current in the machine, which offer a very high resolution. Unfortunately these do not allow the different components of a complex filling pattern to be measured separately. A hybrid filling mode delivered at the ESRF consists of one third of the ring filled with bunches with a single highly populated bunch in the middle of the two-thirds gap. The lifetime of these two components may be very different. Similarly the two components are injected separately and can be monitored separately using a fast current transformer (FCT) or an integrating current transformer (ICT). The signals from these devices can be analysed using high speed analogue to digital converters operating ...

  7. 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.

  8. Measuring the electron beam energy in a magnetic bunch compressor

    International Nuclear Information System (INIS)

    Within this thesis, work was carried out in and around the first bunch compressor chicane of the FLASH (Free-electron LASer in Hamburg) linear accelerator in which two distinct systems were developed for the measurement of an electron beams' position with sub-5 μm precision over a 10 cm range. One of these two systems utilized RF techniques to measure the difference between the arrival-times of two broadband electrical pulses generated by the passage of the electron beam adjacent to a pickup antenna. The other system measured the arrival-times of the pulses from the pickup with an optical technique dependent on the delivery of laser pulses which are synchronized to the RF reference of the machine. The relative advantages and disadvantages of these two techniques are explored and compared to other available approaches to measure the same beam property, including a time-of-flight measurement with two beam arrival-time monitors and a synchrotron light monitor with two photomultiplier tubes. The electron beam position measurement is required as part of a measurement of the electron beam energy and could be used in an intra-bunch-train beam-based feedback system that would stabilize the amplitude of the accelerating field. By stabilizing the accelerating field amplitude, the arrival-time of the electron beam can be made more stable. By stabilizing the electron beam arrival-time relative to a stable reference, diagnostic, seeding, and beam-manipulation lasers can be synchronized to the beam. (orig.)

  9. 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.

  10. Single Shot Electron-Beam Bunch Length Measurements

    CERN Document Server

    Berden, G; Oepts, D; Van der Meer, A F G

    2003-01-01

    It is recognised by the Instrumentation community that 4th generation light sources (like TESLA, LCLS) are posing some of the most stringent requirements on beam diagnostics. Among these, the single-shot electro-optic measurement of the bunch length and shape in the sub-picosecond domain is an ongoing development. The electro-optic detection method makes use of the fact that the local electric field of a highly relativistic electron bunch moving in a straight line is almost entirely concentrated perpendicular to its direction of motion. This electric field makes an electro-optic crystal placed in the vicinity of the beam birefringent. The amount of birefringence depends on the electric field and is probed by monitoring the change of polarization of the wavelength components of a chirped, synchronized Ti:sapphire laser pulse. This talk will provide details of the experimental setup at the Free Electron Laser for Infrared eXperiments (FELIX) in Nieuwegein, The Netherlands, where single shot images have been obt...

  11. Booster's coupled bunch damper upgrade

    Energy Technology Data Exchange (ETDEWEB)

    William A. Pellico and D. W. Wildman

    2003-08-14

    A new narrowband active damping system for longitudinal coupled bunch (CB) modes in the Fermilab Booster has recently been installed and tested. In the past, the Booster active damper system consisted of four independent front-ends. The summed output was distributed to the 18, h=84 RF accelerating cavities via the RF fan-out system. There were several problems using the normal fan-out system to deliver the longitudinal feedback RF. The high power RF amplifiers normally operate from 37 MHz to 53 MHz whereas the dampers operate around 83MHz. Daily variations in the tuning of the RF stations created tuning problems for the longitudinal damper system. The solution was to build a dedicated narrowband, Q {approx} 10, 83MHz cavity powered with a new 3.5kW solid-state amplifier. The cavity was installed in June 2002 and testing of the amplifier and damper front-end began in August 2002. A significant improvement has been made in both operational stability and high intensity beam damping. At present there are five CB modes being damped and a sixth mode module is being built. The new damper hardware is described and data showing the suppression of the coupled-bunch motion at high intensity is presented.

  12. Generation of ultrashort electron bunches by colliding laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, C.B.; Lee, P.B.; Wurtele, J.S. [Department of Physics, University of California at Berkeley, Berkeley, California 94720 (United States); Esarey, E. [Beam Physics Branch, Plasma Physics Division, Navel Research Laboratory, Washington, District of Columbia 20375 (United States); Leemans, W.P. [Center for Beam Physics, Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    1999-07-01

    A proposed laser-plasma based relativistic electron source [E. Esarey {ital et al.}, Phys. Rev. Lett. {bold 79}, 2682 (1997)] using laser triggered injection of electrons is investigated. The source generates ultrashort electron bunches by dephasing and trapping background plasma electrons undergoing fluid oscillations in an excited plasma wake. The plasma electrons are dephased by colliding two counter-propagating laser pulses which generate a slow phase velocity beat wave. Laser pulse intensity thresholds for trapping and the optimal wake phase for injection are calculated. Numerical simulations of test particles, with prescribed plasma and laser fields, are used to verify analytic predictions and to study the longitudinal and transverse dynamics of the trapped plasma electrons. Simulations indicate that the colliding laser pulse injection scheme has the capability to produce relativistic femtosecond electron bunches with fractional energy spread of order a few percent and normalized transverse emittance less than 1 mm mrad using 1 TW injection laser pulses. {copyright} {ital 1999 American Institute of Physics.}

  13. Observation of Superposition of Wake Fields Generated by Electron Bunches in a Dielectric-Lined Waveguide

    CERN Document Server

    Shchelkunov, Sergey V; Hirshfield, Jay L; La Pointe, Michael A; Marshall, Thomas C

    2005-01-01

    We report results from an experiment, done at the Accelerator Test Facility, Brookhaven National Laboratory, which demonstrates the successful superposition of wake fields excited by 50MeV bunches which travel ~50cm along the axis of a cylindrical waveguide which is lined with alumina. Wake fields from two short (5-6psec) 0.15-0.35nC bunches are superimposed and the energy losses of each bunch are measured as the separation between the bunches is varied so as to encompass approximately one wake field period (~21cm). A spectrum of 40 TM0m eigenmodes is excited by the bunch. A substantial retarding wake field (2.65MV/m×nC for just the first bunch) is developed because of the short bunches and the narrow vacuum channel diameter (3mm) through which they move. The energy loss of the second bunch exhibits a narrow resonance with a 4mm (13.5psec) footprint. This experiment may be compared with a related experiment reported by a group at the Argonne National Laboratory where a much weaker wake field (~0.1MV...

  14. Optical measurement of the longitudinal ion distribution of bunched ion beams in the ESR

    International Nuclear Information System (INIS)

    An optical technique to study the longitudinal distribution of ions in a bunched ion beam circulating in a storage ring is presented. It is based on the arrival-time analysis of photons emitted after collisional excitation of residual gas molecules. The beam-induced fluorescence was investigated in the ultraviolet regime with a channeltron and in the visible region using a photomultiplier tube. Both were applied to investigate the longitudinal shape of bunched and electron-cooled 209Bi80+ ion beams at about 400 MeV/u in the experimental storage ring (ESR) at GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. Bunch lengths were determined with an uncertainty of about 0.5 m using the UV-sensitive channeltron and with slightly lower accuracy from the photomultiplier data due to the slower transitions in the red region of the spectrum. The Gaussian shape of the longitudinal distribution of ions inside the bunch was confirmed. With the information of the transverse beam size that can be measured simultaneously by a newly installed ionization profile monitor (IPM) at the ESR, an accurate determination of the ion density in the bunched beam will be allowed. -- Highlights: ► Optical methods to measure the bunch shape of ion beam at storage ring. ► High resolution of bunch length was obtained from the UV-sensitive channeltron. ► The Gaussian shape of longitudinal distribution of the ions in the bunch was confirmed

  15. Sub-picosecond bunch length measurement at the TESLA test facility

    International Nuclear Information System (INIS)

    Sub-picosecond electron bunches are required for the operation of future VUV and X-ray Free Electron Lasers. A streak camera, a Martin-Puplett interferometer and a longitudinal phase space rotation method have been applied at the TESLA Test Facility linac to measure electron bunch lengths

  16. 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

  17. 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.

  18. 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

  19. Excitation of wake waves in plasma by a succession of charged particle bunches. I

    International Nuclear Information System (INIS)

    The problem of excitation of wake waves in plasma by a succession of charged particle bunches is considered in the linear approximation. The case of resonant amplification of the wake field taking place for definite relations between the bunch parameters is analyzed. 11 refs

  20. Development of non-invasive monitoring system to measure bunch-by-bunch charge density distribution in 6D phase space

    International Nuclear Information System (INIS)

    We are developing the ultimate non-destructive monitor to measure 6D-phase space charge density distribution of electron bunches shot by shot. Our single-shot 6-D bunch monitor consists of four or six 3-D bunch charge distribution (3D-BCD) monitors based on triplet 3D-BCD elements installed in non-dispersive and dispersive sections of a beam drift transport line. We are planning to use these non-destructive triplet bunch monitor components, not only for a 3-D bunch (3D-BCD) monitor, but also as an electron energy chirping monitor in dispersive sections of the injection line for SPring-8 II from SACLA linac. In 2013, we upgraded the SPring-8 photoinjector test facility to be able to accelerate up to 85 MeV and installed a magnetic chicane to compress bunches down to 30 fs (FWHM). A 3D-BCD monitor evolved from simple encoding of EO sampling into a multiplexing technique with a single probe laser pulse for multiple EO crystal detectors in a manner of spectral decoding (demultiplexing). We realized demultiplexing as an imaging spectrograph with eight-track simultaneous detection in the area array CCD of a high-speed gated I.I. camera. Transverse detections of bunch slices are done by analyzing the higher order moments of the bunch slice charge density distributions. For achieving the upper limit of temporal resolution, we are preparing to combine high-temporal-response EO-detector organic crystals and an octave broadband probe laser pulse with a linear chirp rate of 1 fs/nm. We are developing an EO-probe laser pulse with ∼10 μJ pulse energy and bandwidth over 300 nm (FWHM; flattop spectrum). (author)

  1. 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

  2. Bunch Compressor Beamlines for the Tesla and S Band Linear Colliders

    International Nuclear Information System (INIS)

    A detailed design for a single stage beam bunch length compressor for both the TESLA and the S-Band Linear Collider (SBLC) is presented. Compression is achieved by introducing an energy-position correlation along the bunch with an rf section at zero-crossing phase followed by a short bending section with energy dependent path length (momentum compaction). The motivation for a wiggler design is presented and many of the critical single bunch tolerances are evaluated. A solenoid based spin rotator is included in the design and transverse emittance tuning elements, diagnostics and tuning methods are described. Bunch length limitations due to second order momentum compaction and sinusoidal rf shape are discussed with options for compensation. Finally, the disadvantages of bunch compression using a 180o arc are discussed

  3. An Electron Bunch Compression Scheme for a Superconducting Radio Frequency Linear Accelerator Driven Light Source

    International Nuclear Information System (INIS)

    We describe an electron bunch compression scheme suitable for use in a light source driven by a superconducting radio frequency (SRF) linac. The key feature is the use of a recirculating linac to perform the initial bunch compression. Phasing of the second pass beam through the linac is chosen to de-chirp the electron bunch prior to acceleration to the final energy in an SRF linac ('afterburner'). The final bunch compression is then done at maximum energy. This scheme has the potential to circumvent some of the most technically challenging aspects of current longitudinal matches; namely transporting a fully compressed, high peak current electron bunch through an extended SRF environment, the need for a RF harmonic linearizer and the need for a laser heater. Additional benefits include a substantial savings in capital and operational costs by efficiently using the available SRF gradient.

  4. Bunch Compressor Beamlines for the Tesla and S Band Linear Colliders

    CERN Document Server

    Emma, P

    2003-01-01

    A detailed design for a single stage beam bunch length compressor for both the TESLA and the S-Band Linear Collider (SBLC) is presented. Compression is achieved by introducing an energy-position correlation along the bunch with an rf section at zero-crossing phase followed by a short bending section with energy dependent path length (momentum compaction). The motivation for a wiggler design is presented and many of the critical single bunch tolerances are evaluated. A solenoid based spin rotator is included in the design and transverse emittance tuning elements, diagnostics and tuning methods are described. Bunch length limitations due to second order momentum compaction and sinusoidal rf shape are discussed with options for compensation. Finally, the disadvantages of bunch compression using a 180 sup o arc are discussed.

  5. Commissioning of TTF2 Bunch Compressor for the Femtosecond (FS) FEL Mode Operation

    CERN Document Server

    Kim, Yujong

    2005-01-01

    To get lasing at TTF2, we should supply high quality electron beams with a high peak current, a low slice emittance, and a low slice energy spread. To supply a high peak current, we compress bunch length with two bunch compressors. During TTF2 lasing period, there was no available special bunch length diagnostic tool such as LOLA cavity or streak camera. However we could optimize TTF2 bunch compressors by monitoring pyro-electric detector signal, by measuring emittance, and by monitoring beam images at chicane center and dump region, and by comparing operational machine conditions with simulation results. In this paper, we describe our various commissioning experiences of TTF2 bunch compressor to generate a femtosecond-long spike with a high peak current.

  6. Dynamics of electron bunches at the laser-plasma interaction in the bubble regime

    Science.gov (United States)

    Maslov, V. I.; Svystun, O. M.; Onishchenko, I. N.; Tkachenko, V. I.

    2016-09-01

    The multi-bunches self-injection, observed in laser-plasma accelerators in the bubble regime, affects the energy gain of electrons accelerated by laser wakefield. However, understanding of dynamics of the electron bunches formed at laser-plasma interaction may be challenging. We present here the results of fully relativistic electromagnetic particle-in-cell (PIC) simulation of laser wakefield acceleration driven by a short laser pulse in an underdense plasma. The trapping and acceleration of three witness electron bunches by the bubble-like structures were observed. It has been shown that with time the first two witness bunches turn into drivers and contribute to acceleration of the last witness bunch.

  7. 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.

  8. Electron cloud induced single bunch instability, simulation by tracking with a pre-computed wake matrix

    Energy Technology Data Exchange (ETDEWEB)

    Markovik, Aleksandar; Rienen, Ursula van [Fakultaet fuer Informatik und Elektrotechnik, Rostock (Germany)

    2012-07-01

    A PIC simulation of the interaction of a positron beam with an e-cloud yields the wake kick from the electrons on the tail particles of the bunch. Thereby a certain offset in the transverse centroid position of the bunch perturbs the electron distribution which than exercise a transverse kick on the following bunch particles. By slicing the bunch in axial direction and computing the wake kick from the e-cloud due to the vertical offset of each slice we receive a triangular wake matrix. With such a pre-computed wake matrix, for a certain e-cloud density, we investigate the stability of a single bunch by tracking it through the linear optics of the storage ring while at each turn applying the kick from the e-cloud.

  9. Radiation of the electron bunch moving in non-regular fields

    CERN Document Server

    Gevorgian, Lekdar

    2012-01-01

    The problem of spontaneous radiation of the electron bunch grazing into a charged metallic surface with randomly distributed needle shaped asperities is considered. Distances between two neighboring asperities have been described by gamma distribution. Being repealed by highly charged asperities the electrons of the bunch move along non-regular periodical trajectories in the planes parallel to the metallic surface. The spatial periods of the trajectories are random quantities which are described by the same gamma distribution. The radiation characteristics of the bunch have been obtained. It is shown that the angular distributions of the number of photons radiated from the bunch and from a single electron are the same but the frequency distribution of the bunch is being drastically changed at the hard frequency region. It is proposed to develop a new non-destructive method for investigation of the metal surface roughness. The frequency distribution of the number of photons radiated under the zero angle has be...

  10. 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.

  11. 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.

  12. Wake excited in plasma by an ultra-relativistic point-like bunch

    CERN Document Server

    Stupakov, G; Khudik, V; Shvets, G

    2016-01-01

    A plasma flow behind a relativistic electron bunch propagating through a cold plasma is found assuming that the transverse and longitudinal dimensions of the bunch are small and the bunch can be treated as a point charge. In addition, the bunch charge is assumed small. A simplified system of equations for the plasma electrons is derived and it is shown that, through a simple rescaling of variables, the bunch charge can be eliminated from the equations. These equations have a unique solution, with an ion cavity formed behind the driver. The equations are solved numerically and the scaling of the cavity dimensions with the driver charge is obtained. A numerical solution for the case of a positively charged driver is also found.

  13. RFKO system for single-bunch operation of Hefei light source

    International Nuclear Information System (INIS)

    A new RFKO (RF Knock Out) system for partial filling operation is in commission at the Hefei light source storage ring. This system is composed of a frequency divider, waveform generator, and vector signal source and wideband amplifier. The in-phase signal of beam bunch is obtained by dividing the reference signal from the storage ring's RF system. Triggered by the in-phase signal, the waveform generator outputs a pulse burst. Modulated by the pulse, the waveform generator produces the RFKO signal, and the RFKO signal is applied to the strip line after amplification. The single bunch operation is achieved in this way and the current has reached 18 mA at present. Some bunch-train patterns such as 3-train with 6-bunch and non-uniform bunch train are also tested. (authors)

  14. Emittance growth and energy loss due to coherent synchrotron radiation in a bunch compressor

    International Nuclear Information System (INIS)

    Electron bunches of high charge (up to 10 nC) are compressed in length in the Compact Linear Collider Test Facility magnetic chicane to less than 0.4 mm rms. The short bunches radiate coherently in the chicane magnetic field, and the horizontal and longitudinal phase space density distributions are affected. This paper reports the results of beam emittance and momentum measurements. Horizontal and vertical emittances and momentum spectra were measured for different bunch compression factors and bunch charges. In particular, for 10 nC bunches, the mean beam momentum decreased by about 5% while the rms momentum spread increased from 2% to 8%. The experimental results are compared with simulations made with the code TRAFIC4

  15. An Electron Bunch Compression Scheme for a Superconducting Radio Frequency Linear Accelerator Driven Light Source

    Energy Technology Data Exchange (ETDEWEB)

    C. Tennant, S.V. Benson, D. Douglas, P. Evtushenko, R.A. Legg

    2011-09-01

    We describe an electron bunch compression scheme suitable for use in a light source driven by a superconducting radio frequency (SRF) linac. The key feature is the use of a recirculating linac to perform the initial bunch compression. Phasing of the second pass beam through the linac is chosen to de-chirp the electron bunch prior to acceleration to the final energy in an SRF linac ('afterburner'). The final bunch compression is then done at maximum energy. This scheme has the potential to circumvent some of the most technically challenging aspects of current longitudinal matches; namely transporting a fully compressed, high peak current electron bunch through an extended SRF environment, the need for a RF harmonic linearizer and the need for a laser heater. Additional benefits include a substantial savings in capital and operational costs by efficiently using the available SRF gradient.

  16. Electron cloud induced single bunch instability, simulation by tracking with a pre-computed wake matrix

    International Nuclear Information System (INIS)

    A PIC simulation of the interaction of a positron beam with an e-cloud yields the wake kick from the electrons on the tail particles of the bunch. Thereby a certain offset in the transverse centroid position of the bunch perturbs the electron distribution which than exercise a transverse kick on the following bunch particles. By slicing the bunch in axial direction and computing the wake kick from the e-cloud due to the vertical offset of each slice we receive a triangular wake matrix. With such a pre-computed wake matrix, for a certain e-cloud density, we investigate the stability of a single bunch by tracking it through the linear optics of the storage ring while at each turn applying the kick from the e-cloud.

  17. 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.

  18. Stability of higher-order longitudinal modes in a bunched beam without mode coupling

    International Nuclear Information System (INIS)

    The theory of longitudinal instabilities of bunched beams was proposed by F. Sacherer. Starting from the Vlasov equation, he derived the integral equation for the perturbed distribution function. While the general method to solve the integral equation was given by Sacherer, a number of other papers discussing longitudinal bunched beam instability have also been published. Here we want to propose another formalism with which we can treat the integral equation without mode coupling for the case of a Gaussian bunch. We then generalize the formalism for the other bunch distributions, and derive a practical method to analyze the instability for the case of a parabolic bunch. While the solution of the Sacherer equation that we find is not new, we present another approach to solve it. Since the integral equation for the transverse instability is similar to that for the longitudinal instability, this formalism is also useful for the transverse case. 12 figs., 4 figs

  19. Investigation of the longitudinal charge distribution of electron bunches at the VUV-FEL using the transverse deflecting cavity LOLA

    International Nuclear Information System (INIS)

    In this thesis, the theory, commissioning, and results of the transverse deflecting cavity, LOLA IV, for longitudinal bunch shape and bunch length measurements at the DESY Vacuum-Ultraviolet Free Electron Laser (VUV-FEL) are presented. The design of the linear accelerator foresees bunch lengths in the order of 100 fs and below. This poses a serious challenge for diagnosing the longitudinal structure of these bunches. LOLA promises resolution down to 17 fs. (orig.)

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. Can YAG screen accept LEReC bunch train?

    Energy Technology Data Exchange (ETDEWEB)

    Seletskiy, S. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Thieberger, P. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Miller, T. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2016-05-18

    LEReC RF diagnostic beamline is supposed to accept 250 us long pulse trains of 1.6 MeV – 2.6 MeV (kinetic energy) electrons. This beamline is equipped with YAG profile monitor. Since we are interested in observing only the last macro bunch in the train, one of the possibilities is to install a fast kicker and a dedicated dump upstream of the YAG screen (and related diagnostics equipment). This approach is expensive and challenging from engineering point of view. Another possibility is to send the whole pulse train to the YAG screen and to use a fast gated camera (such as Imperex B0610 with trigger jitter under 60ns [1]) to observe the image from the last pulse only. In this paper we study the feasibility of the last approach.

  5. 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.

  6. 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.

  7. Linear Vlasov Analysis for Stability of a Bunched Beam

    International Nuclear Information System (INIS)

    The authors study the linearized Vlasov equation for a bunched beam subject to an arbitrary wake function. Following Oide and Yokoya, the equation is reduced to an integral equation expressed in angle-action coordinates of the distorted potential well. Numerical solution of the equation as a formal eigenvalue problem leads to difficulties, because of singular eigenmodes from the incoherent spectrum. The authors rephrase the equation so that it becomes non-singular in the sense of operatory theory, and has only regular solutions for coherent modes. They report on a code that finds thresholds of instability by detecting zeros of the determinant of the system as they enter the upper-half frequency plane, upon increase of current. Results are compared with a time-domain integration of the nonlinear Vlasov equation with a realistic wake function for the SLC damping rings. There is close agreement between the two calculations

  8. Linear Vlasov Analysis for Stability of a Bunched Beam

    Energy Technology Data Exchange (ETDEWEB)

    Warnock, R

    2004-08-12

    The authors study the linearized Vlasov equation for a bunched beam subject to an arbitrary wake function. Following Oide and Yokoya, the equation is reduced to an integral equation expressed in angle-action coordinates of the distorted potential well. Numerical solution of the equation as a formal eigenvalue problem leads to difficulties, because of singular eigenmodes from the incoherent spectrum. The authors rephrase the equation so that it becomes non-singular in the sense of operatory theory, and has only regular solutions for coherent modes. They report on a code that finds thresholds of instability by detecting zeros of the determinant of the system as they enter the upper-half frequency plane, upon increase of current. Results are compared with a time-domain integration of the nonlinear Vlasov equation with a realistic wake function for the SLC damping rings. There is close agreement between the two calculations.

  9. Characterization of cellulose extracted from oil palm empty fruit bunch

    Science.gov (United States)

    Sisak, Muhammad Asri Abdul; Daik, Rusli; Ramli, Suria

    2015-09-01

    Recently, cellulose has been studied by many researchers due to its promising properties such as biodegradability, biocompatibility, hydrophilicity and robustness. Due to that it is applied in many fields such as paper, film, drug delivery, membranes, etc. Cellulose can be extracted from various plants while oil palm empty fruit bunch (OPEFB) is the one of its sources. In this study, cellulose was extracted by chemical treatments which involved the use of formic acid and hydrogen peroxide to remove hemicellulose and lignin components. Maximum yield was 43.22%. Based on the FT-IR spectra, the peak of wax (1735 cm-1), hemicellulose (1375 cm-1) and lignin (1248 cm-1 and 1037 cm-1) were not observed in extracted cellulose. TGA analysis showed that the extracted cellulose starts to thermally degrade at 340 °C. The SEM analysis suggested that the cellulose extracted from OPEFB was not much different from commercial cellulose.

  10. Can YAG screen accept LEReC bunch train?

    Energy Technology Data Exchange (ETDEWEB)

    Seletskiy, S. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Thieberger, P. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Miller, T. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2016-05-18

    LEReC RF diagnostic beamline is supposed to accept 250 us long pulse trains of 1.6 MeV – 2.6 MeV (kinetic energy) electrons. This beamline is equipped with YAG profile monitor. Since we are interested in observing only the last macro bunch in the train, one of the possibilities is to install a fast kicker and a dedicated dump upstream of the YAG screen (and related diagnostics equipment). This approach is expensive and challenging from engineering point of view. Another possibility is to send the whole pulse train to the YAG screen and to use a fast gated camera (such as Imperex B0610 with trigger jitter under 60ns) to observe the image from the last pulse only. In this paper we study the feasibility of the last approach.

  11. Analyzing gigahertz bunch length instabilities with a digital signal processor

    International Nuclear Information System (INIS)

    A bunch length instability, nicknamed the ''sawtooth'', because of its transient behavior, has been observed at high current running in the Stanford Linear Collider (SLC) electron damping ring. The incompatibility of this instability with successful SLC naming prompted its study using a high bandwidth real-time spectrum analyzer, the Tektronix 3052 digital signal processor (DSP) system. This device has been used to study energy ramping in storage rings but this is the first time it has been used to study transient instability phenomena. It is a particularly valuable tool for use in understanding non-linear, multiple frequency phenomena. The frequency range of this device has been extended through the use of radio frequency (RF) down converters. This paper describes the measurement setup and presents some of the results

  12. Emittance Correction in the 2006 ILC Bunch Compressor

    International Nuclear Information System (INIS)

    A recent study [1] has indicated substantial potential emittance growth in the ILC bunch compressor due to quad misalignments, BPM misalignments, and pitches in the RF cavities. Table 1 summarizes several results from [1]. In this simulation, quad misalignments and cavity pitches are Gaussian distributed and are considered with respect to the nominal survey line; BPM misalignments are also Gaussian-distributed but are considered with respect to the quadrupole axis. It is assumed that the BPM offsets with respect to the quads are found in a previous quad-shunting BBA step which is not simulated. In this study we seek to repeat the studies documented above, and additionally to perform a study in which additional dispersion bumps are used to further reduce the projected emittance

  13. STEAM EXPLOSION PULPING OF OIL PALM EMPTY FRUIT BUNCH FIBER

    Directory of Open Access Journals (Sweden)

    Xiwen Wang,

    2012-01-01

    Full Text Available Steam explosion pulping was evaluated for oil palm empty fruit bunches fiber. The fiber morphology was observed by SEM and TEM. Results indicated that lignin was molten and the cell wall damaged after the steam explosion pulping and that the fiber was partly separated at the same time. The results of handsheet tests showed that the steam exploded pulp had a high yield (78.2%, good physical properties (especially for ring crush 8.6 N•m/g, and low effluent load (SS=910 mg/L; BOD5=3952 mg/L; CODCr=8140 mg/L. The SEP pulp from oil palm EFB fiber was very suitable for packaging paper when combined with American OCC pulp.

  14. Bio-oil derived from empty fruit bunches

    Energy Technology Data Exchange (ETDEWEB)

    Abdullah, N. [School of Physics, Universiti Sains Malaysia, 11800 Minden, Penang (Malaysia); Gerhauser, H. [ECN Biomass, Coal and Environmental Research, Petten (Netherlands)

    2008-08-15

    The fast pyrolysis of washed and unwashed empty fruit bunches (EFB), a waste of the palm oil industry, is investigated in this study. Firstly, the composition and particle size distribution of the washed and unwashed feedstock were determined and the thermal degradation behaviour was analysed by TGA. Then a 150 g/h fluidised bed bench scale fast pyrolysis unit was used to study the impact of key variables: reactor temperature in the range 425-550C and feedstock ash content in the range 1.03-5.43 mf wt%. The properties of the liquid product were analysed and compared with wood derived bio-oil and petroleum fuels. It was found that the maximum ash content of washed feedstock that still yields homogenous liquids is less than about 3 mf wt%. The experiments also indicated that the fast pyrolysis of washed EFB with a low ash content gave similar yields as commonly obtained for wood.

  15. VISCOSITY ANALYSIS OF EMPTY FRUIT BUNCH (EFB BIO-OIL

    Directory of Open Access Journals (Sweden)

    Z.S. Nazirah

    2013-12-01

    Full Text Available Empty fruit bunches (EFB are one of the solid wastes produced by the palm oil industry, which is increasing rapidly. The aim of this paper is to analyse the viscosity of empty fruit bunch (EFB bio-oil that can be extracted from all solid waste EFB as a sample, and a few processes were executed. The samples underwent two processes, which were pre-treatment and pyrolysis. The pre-treatment involved three processes, namely, cutting, shredding and sieving, which were necessary in order to prepare EFB into a particle size suitable for the reactor. After that, the samples were fed into the feedback reactor as feedstock for the pyrolysis process to produce bio-oil. Once the bio-oil was produced, its viscosity was tested using the Brookfield Viscometer in two conditions: before and after the chemical reaction. The bio-oil was treated by adding 10 ml and 20 ml of acetone respectively through the chemical reaction. The viscosity test was carried out at different temperatures, which were 25°C, 30°C, 35°C, 40°C, 45°C and 50°C respectively. The observed viscosity of the EFB bio-oil varied and was higher as the temperature decreased. In addition, the viscosity of the EFB bio-oil was higher when it reacted chemically with the acetone added. Therefore, the results showed that the chemical reaction with acetone has the potential to increase the viscosity of EFB bio-oil.

  16. Measuring the electron beam energy in a magnetic bunch compressor

    Energy Technology Data Exchange (ETDEWEB)

    Hacker, Kirsten

    2010-09-15

    Within this thesis, work was carried out in and around the first bunch compressor chicane of the FLASH (Free-electron LASer in Hamburg) linear accelerator in which two distinct systems were developed for the measurement of an electron beams' position with sub-5 {mu}m precision over a 10 cm range. One of these two systems utilized RF techniques to measure the difference between the arrival-times of two broadband electrical pulses generated by the passage of the electron beam adjacent to a pickup antenna. The other system measured the arrival-times of the pulses from the pickup with an optical technique dependent on the delivery of laser pulses which are synchronized to the RF reference of the machine. The relative advantages and disadvantages of these two techniques are explored and compared to other available approaches to measure the same beam property, including a time-of-flight measurement with two beam arrival-time monitors and a synchrotron light monitor with two photomultiplier tubes. The electron beam position measurement is required as part of a measurement of the electron beam energy and could be used in an intra-bunch-train beam-based feedback system that would stabilize the amplitude of the accelerating field. By stabilizing the accelerating field amplitude, the arrival-time of the electron beam can be made more stable. By stabilizing the electron beam arrival-time relative to a stable reference, diagnostic, seeding, and beam-manipulation lasers can be synchronized to the beam. (orig.)

  17. Hydroxynortriptyline of Empty Fruit Bunches Fibre using Polyethylene glycol (PEG)

    International Nuclear Information System (INIS)

    The aim of this study was to investigate the reaction of oil palm empty fruit bunches fibre (EFBF) via chemical modification and hydroxynortriptyline method using polyethylene glycol (PEG). The first stage was the modification of EFB fibre using NaOH and isopropanol. The next stage was the preparation of hydroxypropylated-empty fruit bunches fibre (HP-EFBF), using different molecular weight of PEG (6,000, 8,000 and 10,000). The characterisation involved in this study were conducted by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetry analysis (TGA), determination of kinetic activation energy (Ea), X-ray diffraction (XRD), cellulose crystallinity index (CrI) and weight increment of the HP-EFB fibre. SEM results showed the surface of HP-EFBF swelled and craters formed along the surface of the fibre. IR spectrum also showed OH stretching band in EFB without treatment is 3402 cm-1, but after hydroxynortriptyline process, the OH stretching band in HP-EFBF (10000, 8000 and 6000) slightly shifted to 3392, 3384 and 3370 cm-1, respectively. TGA showed the thermal stability of HP-EFBF 6,000 was lower than HP-EFBF 8,000 and 10,000. After chemical modification, the activation energy, Ea increased from 32.4 to 51.9 kJ/ mol more than EFB without treatment, 12.5 kJ/ mol. XRD showed that diffraction peak (002) shifted to the smaller 2θ angle and the peaks (101, 10I) disappeared after hydroxynortriptyline process. Crystallinity index, of EFB without treatment decreased from 27 % to 25 % after chemical modification. The higher the molecular weight of the PEG, the greater the weight increment of the HP-EFBF. (author)

  18. Bunch Length Measurements at the JLab FEL Using Coherent Transition and Synchrotron Radiation

    Science.gov (United States)

    Evtushenko, P.; Coleman, J.; Jordan, K.; Klopf, J. Michael; Neil, G.; Williams, G. P.

    2006-11-01

    The JLab FEL is routinely operated with sub-picosecond bunches. The short bunch length is important for high gain of the FEL. Coherent transition radiation has been used for the bunch length measurements for many years. This diagnostic can be used only in the pulsed beam mode. It is our goal to run the FEL with CW beam and a 74.85 MHz micropulse repetition rate, which, with the 135 pC nominal bunch charge corresponds to the beam average current of 10 mA, Hence it is very desirable to have the possibility of making bunch length measurements when running CW beam with any micropulse frequency. We use a Fourier transform infrared (FTIR) interferometer, which is essentially a Michelson interferometer, to measure the spectrum of the coherent synchrotron radiation generated in the last dipole of the magnetic bunch compressor upstream of the FEL wiggler. This noninvasive diagnostic provides bunch length measurements for CW beam operation at any micropulse frequency. We also compare the measurements made with the help of the FTIR interferometer with data obtained using the Martin-Puplett interferometer. Results of the two diagnostics agree within 15 %. Here we present a description of the experimental setup, data evaluation procedure and results of the beam measurements.

  19. A novel source of MeV positron bunches driven by energetic protons for PAS application

    Science.gov (United States)

    Tan, Zongquan; Xu, Wenzhen; Liu, Yanfen; Xiao, Ran; Kong, Wei; Ye, Bangjiao

    2014-11-01

    This paper proposes a novel methodology of MeV positrons generation for PAS application. Feasibility of this proposal analyzed by G4Beamline and Transport have shown reasonable success. Using 2 Hz, 1.6 GeV, 100 ns and 1.5 μC/bunch proton bunches for bombarding a graphite target, about 100 ns e+ bunches are generated. Quasi-monochromatic positrons in the range of 1-10 MeV included in these bunches have a flux of >107/s, peak brightness of 1014/s. A magnetic-confinement beamline is utilized to transport the positrons and a "Fast Beam Chopper" is unprecedentedly extended to chop those relativistic bunches. The positron beam can be finally characterized by the energy range of 1-10 MeV and bunch width from one hundred ps up to 1 ns. Such ultrashort bunches can be useful in tomography-type positron annihilation spectroscopy (PAS) as well as other applications.

  20. 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

  1. Bunch stability during high-gradient wakefield generation in a dielectric-lined waveguide

    International Nuclear Information System (INIS)

    A recently developed analytic theory for wakefields generated when a charge bunch, or train of bunches, passes along a dielectric-lined waveguide is applied to examine stability issues for this system. Such a configuration could be the key element in a two-beam accelerator to create colliding TeV-range electron and positron beams. It is shown that a 587 MV/m peak acceleration gradient can be achieved when a train of five 2 nC, 1.0 GeV, 0.20 mm long drive bunches passes along the axis of an alumina-lined waveguide (ε=9.5) with inner and outer radii 0.50 and 5.0 mm. The energy gain of a 0.2 nC test bunch in a 4 m long stage under these conditions is shown to be 1.48 GeV, for an average acceleration gradient of 370 MV/m. However, when a drive bunch is injected parallel to, but displaced from, the waveguide axis, transverse (mainly dipole) forces cause the tail of the bunch to swerve sharply toward the waveguide wall (head-to-tail instability), and to intersect the wall after traversing a relatively short distance. These results suggest that successful exploitation of the appealing strong wakefields generated by a train of drive bunches will require some means of transverse stabilization, such as an array of externally applied focusing and defocusing quadrupoles

  2. Measurement of Bunch Length Using Spectral Analysis of Incoherent Radiation Fluctuations

    International Nuclear Information System (INIS)

    A measurement of the longitudinal beam profile of a relativistic charged particle beam is an important tool in modern accelerators. For bunch lengths in the range of picoseconds, such measurements can be performed by means of a streak camera. Shorter bunches usually require special techniques. In this paper we describe a novel technique that allows obtaining properties of a bunch of charged particles through measurement of the fluctuations of incoherent radiation from the bunch. Due to shot-noise fluctuations in the longitudinal beam density, this incoherent radiation has a spectrum, which consists of random spikes with width inversely proportional to the bunch length. The convolution of the beam current can also be obtained from the radiation spectrum. After the convolution function is found, the phase retrieval technique can be applied to recover the bunch shape. This technique has been used to analyze the shape of the 4-ps-long bunches at the Advanced Photon Source self-amplified spontaneous emission free-electron laser (SASE FEL) experiment

  3. 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.

  4. Measurement of bunch length in Indus-1 storage ring using fast photodiode

    International Nuclear Information System (INIS)

    The length of electron bunches in a storage ring is an important parameter for both synchrotron radiation users and accelerator physicists. Several methods are used for measurements of bunch length using electronic and optical instruments. We have measured temporal profile of synchrotron radiation emitted from dipole magnet of Indus-1 by using fast photodiode. Bunch length is calculated by assuming gaussian profile for the particles inside bunch. The results show that bunch length is increasing with the decrease of gap voltage of RF cavity. These measurements were carried out at low beam current; at high voltage results are in close agreement with theory and the values estimated using ZAP code. In the second experiment, the results show that bunch length increases with the increase of beam current inside the bunch, and above threshold current, it follows Chao-Gareyte scaling law. The longitudinal broadband impedance for Indus-1 SRS was estimated using Keil-Schnell criterion and results were compared with theoretical estimated values using ZAP code.

  5. 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...

  6. Beam test of multi-bunch energy compensation system in the accelerator test facility at KEK

    International Nuclear Information System (INIS)

    A beam test of the multi-bunch energy compensation system (ECS) was performed using the ΔF method with the 2856±4.327 HMz accelerating structures in the accelerator test facility (ATF) at KEK. The 1.54 GeV S-band linac of the ATF was designed to accelerate a multi-bunch beam the consists of 20 bunches with 2.8 ns spacing. The multi-bunch beam with 2.0 x 1010 electrons/bunch has an energy deviation of about 8.5% at the end of the linac due to transient beam loading without ECS. The ATF linac is the injector of the ATF damping ring (DR), whose energy acceptance is ±0.5%. The beam loading compensation system is necessary in the ATF linac for the successful injection of multi-bunch into DR. The rf system of the linac consists of 8 regular rf units with the SLED system and 2 ECS rf units without the SLED system. The accelerating structures of the regular units are driven at 2856 MHz and the 2 ECS structures are operated with slightly different rf frequencies of 2856±4.327 MHz. In the beam test, we have succeeded in compressing the multi-bunch energy spread within the energy acceptance of the DR using ΔF ECS. The principle of the beam loading compensation system of KEK-ATF and the experimental results are described in this paper. (author)

  7. A hybrid approach for generating ultra-short bunches for advanced accelerator applications

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-01

    Generation of electron beams with high phase-space density, short bunch length and high peak current is an essential requirement for future linear colliders and bright electron beam sources. Unfortunately, such bunches cannot be produced directly from the source since forces from the mutual repulsion of electrons would destroy the brilliance of the beam within a short distance. Here, we detail a beam dynamics study of an innovative two-stage compression scheme that can generate ultra-short bunches without degrading the beam quality. In the first stage, the beam is compressed with an advanced velocity bunching technique in which the longitudinal phase space is rotated so that electrons on the bunch tail become faster than electrons in the bunch head. In the second stage, the beam is further compressed with a conventional magnetic chicane. With the aid of numerical simulations we show that our two-staged scheme is capable to increase the current of a 50 pC bunch to a notable factor of 100 while the emittance growth can be suppressed to 1% with appropriate tailoring of the initial beam distribution.

  8. Development of a photo-cathode rf electron gun for ultra-short bunch generation

    International Nuclear Information System (INIS)

    The photocathode rf electron gun is a high brightness electron source because the initial electron bunch shape can be controlled by the cathode illuminating laser pulse and then the bunch is rapidly accelerated by the high gradient electric field in the rf gun cavity. The rf guns are widely used not only as a injector for large facility but also application researches. At Waseda University, I and collaborators have been developing an rf electron gun since 1999. We performed optimization of cavity structure, improvement of rf tuner and development of photocathode material, then we succeeded in operating 3.6 cell rf gun. In these backgrounds, I conceived a new type rf gun cavity structure for ultra-short electron bunch generation, named Energy-Chirping-Cell attached rf gun (ECC rf gun). Less than 100 fs (rms) bunch can be produced with 100 pC charge by this ECC rf gun in the simulation. Such a high peak current bunch has a possibility to apply for the coherent THz radiation source and single shot electron diffraction microscope. Encouraged by this successful simulation results, we manufactured an ECC rf gun and measured the bunch length at Waseda University. The experimental results showed a good agreement with simulation and we found that the bunch length from ECC rf gun was less than 500 fs (rms). In this paper, the introduction of the photocathode rf gun, principle and experimental results of ECC rf gun, and future prospective will be described. (author)

  9. 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.

  10. Measurement of bunch length in Indus-1 storage ring using fast photodiode

    Energy Technology Data Exchange (ETDEWEB)

    Garg, Akash Deep; Nathwani, R. K.; Holikatti, A. C.; Kumar Karnewar, Akhilesh; Tyagi, Y.; Yadav, S.; Puntambekar, T. A.; Navathe, C. P. [Beam Diagnostics Section, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)

    2012-11-15

    The length of electron bunches in a storage ring is an important parameter for both synchrotron radiation users and accelerator physicists. Several methods are used for measurements of bunch length using electronic and optical instruments. We have measured temporal profile of synchrotron radiation emitted from dipole magnet of Indus-1 by using fast photodiode. Bunch length is calculated by assuming gaussian profile for the particles inside bunch. The results show that bunch length is increasing with the decrease of gap voltage of RF cavity. These measurements were carried out at low beam current; at high voltage results are in close agreement with theory and the values estimated using ZAP code. In the second experiment, the results show that bunch length increases with the increase of beam current inside the bunch, and above threshold current, it follows Chao-Gareyte scaling law. The longitudinal broadband impedance for Indus-1 SRS was estimated using Keil-Schnell criterion and results were compared with theoretical estimated values using ZAP code.

  11. A hybrid approach for generating ultra-short bunches for advanced accelerator applications

    Science.gov (United States)

    Stratakis, Diktys

    2016-06-01

    Generation of electron beams with high phase-space density, short bunch length and high peak current is an essential requirement for future linear colliders and bright electron beam sources. Unfortunately, such bunches cannot be produced directly from the source since forces from the mutual repulsion of electrons would destroy the brilliance of the beam within a short distance. Here, we detail a beam dynamics study of a two-stage compression scheme that can generate ultra-short bunches without degrading the beam quality. In the first stage, a magnetized beam is compressed with a velocity bunching technique in which the longitudinal phase space is rotated so that electrons on the bunch tail become faster than electrons in the bunch head. In the second stage, the beam is further compressed with a magnetic chicane. With the aid of numerical simulations we show that our two-staged scheme is capable to increase the current of a 50 pC bunch by a notable factor of 100 (from 15 A to 1.5 kA) while the emittance growth can be suppressed to 1% with appropriate tailoring of the initial beam distribution.

  12. 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.

  13. Initial simulation studies of electron bunch from RF photocathode gun of DLS project

    International Nuclear Information System (INIS)

    A Free Electron Laser based compact light source, named as Delhi Light Source (DLS), is under construction at IUAC. The facility aims to produce THz and Infrared radiation by injecting high quality electron beam into an undulator magnet. In addition, intense X-rays can be obtained by bombarding the electron beam with a laser beam by the method of Inverse Compton scattering. The complete project is divided in to three phases. The first phase of the project aims at generating pre-bunched electron beam from a 2.6 cell room temperature RF photocathode gun operating at 2.86 GHz. The bunch train with a repetition rate of 10 Hz, will consist of 2, 4, 8 or 16 micro-bunches . By varying the separation between the microbunches, the tuning of the THz radiation produced from the undulator magnet can be performed. Metal photocathode will be used initially to generate the electron micro-bunches to keep the temporal spread small. This paper describes the simulation studies using ASTRA code for optimization of various parameters from RF photocathode gun upto the undulator entrance. The multiple parameters are optimized one at a time, for a single electron bunch, ensuring the desired output parameter is contained within tolerable limits. Beam optics simulation with multi electron bunches are also studied with variable number of 2, 4 and 8 micro-bunches with different micro-bunch spacing. In the simulation studies, attention is paid to optimize the fundamental beam parameters like the transverse emittance, energy spread, transverse/longitudinal beam size etc. The paper describes the simulation results with single and multi-electron bunches. (author)

  14. 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

  15. Build up of electron cloud with different bunch pattern in the presence of solenoid field

    International Nuclear Information System (INIS)

    We have augmented the code POSINST to include solenoid fields, and used it to simulate the build up of electron cloud due to electron multipacting in the PEP-II positron ring. We find that the distribution of electrons is strongly affected by the resonances associated with the cyclotron period and bunch spacing. In addition, we discover a threshold beyond which the electron density grows exponentially until it reaches the space charge limit. The threshold does not depend on the bunch spacing but does depend on the positron bunch population

  16. Buildup of electron cloud with different bunch pattern in the presence of solenoid field

    International Nuclear Information System (INIS)

    We have augmented the code POSINST to include solenoid fields, and used it to simulate the build up of electron cloud due to electron multipacting in the PEP-II positron ring. We find that the distribution of electrons is strongly affected by the resonances associated with the cyclotron period and bunch spacing. In addition, we discover a threshold beyond which the electron density grows exponentially until it reaches the space charge limit. The threshold does not depend on the bunch spacing but does depend on the positron bunch population

  17. Transport of bunches in a dielectric wakefield accelerator using an array of plasma cells

    International Nuclear Information System (INIS)

    An array of short sections of plasma dielectric wakefield accelerator modules spaced by vacuum zones (without plasma) is proposed to avoid the 'underdense' operating regime. A calculation of the dynamics of the accelerated particles in such an array of accelerating-drift sections is given. The parameters of bunches which are available in SLAC are used for this calculation. A dielectric structure using fused silica provides an operating frequency approx 350 GHz. Lengths of plasma and vacuum sections providing stable transportation of the accelerated bunch are found. The bunch size in the focal plane is determined

  18. Spectral reflectance of oil-palm (Elaeis guineensis Jacq.) bunches as indicator for optimal harvesting

    OpenAIRE

    Wunsri, S.; Chittrakarn, T.; Bhongsuwan, T.; Kongsaeng, S.

    2005-01-01

    To determine the appropriate harvesting time of Tenera oil palm bunches, the spectral reflectance of ripening bunches was investigated from images taken by a digital Canon PowerShot A20 camera. Every second day images were taken from selected bunches at an oil-palm estate during the growth of the bunchesfrom immaturity to the over-ripe phase, to trace the changes in color which correlate with the process of ripening. The images were analyzed measuring the changes in the three basic colors red...

  19. Feasibility Study of Accumulator and Compressor for the 6-bunches SPL based Proton Driver

    CERN Document Server

    Aiba, M

    2008-01-01

    Feasibility of the accumulator and the compressor ring for the SPL based proton driver have been studied for a future neutrino factory. The scenario retained for the SPL proton driver uses six bunches, with 10^14 protons in total at 50 Hz. Possible lattices for the accumulator and the compressor are presented. The beam injection/accumulation and the bunch compression are delicate issues and discussed in detail in this note. Throughout the presented study, these difficulties are disclosed not to be critical issues, and together with a discussion on the focusing towards production target, the feasibility of the 6-bunches SPL based proton driver has been confirmed.

  20. Feasibility study of accumulator and compressor for the 6-bunches SPL based proton driver

    CERN Document Server

    Aiba, M

    2008-01-01

    Feasibility studies of the accumulator and the compressor rings for the SPL based proton driver have been studied for a future neutrino factory. The scenario retained for the SPL proton driver uses six bunches, with 10^14 protons in total at 50 Hz. Possible lattices for the accumulator and the compressor are presented. The beam injection/accumulation and the bunch compression are delicate issues and discussed in detail in this note. Throughout the presented study, these difficulties are disclosed not to be critical issues, and together with a discussion on the focusing towards production target, the feasibility of the 6-bunches SPL based proton driver has been confirmed

  1. Developments of components for femto-second real-time bunch shape monitor

    International Nuclear Information System (INIS)

    For the stable SASE operation in XFEL/SPring-8, we have developed the optical components especially for three-dimensional femto-second bunch shape monitor based on Electro-Optic detection as non-destructive real-time single-shot measurements. This bunch shape monitor requires a supercontinuum laser pulse (> 400 nm bandwidth), the optical components for such a laser pulse, and an organic EO material. We report the details of developing status of these components for this bunch shape monitor. (author)

  2. Study of beam parameters of the CERN proton linac using a three dimensional bunch shape monitor

    International Nuclear Information System (INIS)

    A Three Dimensional Bunch Shape Monitor (3D-BSM) has been developed for the CERN Proton Linac 2. A new area for beam studies at high intensities has been opened by this detector. Bunch density distributions in all three dimensions and their variations along the beam pulse can be obtained. Changing field gradients in linac quadrupoles, emittance variation along the bunch has been calculated. Measurements of beam halos become possible thanks to the large dynamic range of the device. Beam parameters at various linac settings have been measured and analysed. (author)

  3. Study of beam parameters of the CERN proton linac using a three dimensional bunch shape monitor

    CERN Document Server

    Feschenko, A V; Ostroumov, P N; Dubois, O; Haseroth, H; Hill, C; Kugler, H; Lombardi, A M; Naito, F; Tanke, E; Vretenar, Maurizio

    1996-01-01

    A Three Dimensional Bunch Shape Monitor (3D-BSM) has been developed for the CERN Proton Linac 2. A new area for beam studies at high intensities has been opened by this detector. Bunch density distributions in all three dimensions and their variations along the beam pulse can be obtained. Changing field gradients in linac quadrupoles, emittance variation along the bunch has been calculated. Measurements of beam halos become possible thanks to the large dynamic range of the device. Beam parameters at various linac settings have been measured and analysed.

  4. Design of femto-second real-time bunch shape monitor based on EO detection

    International Nuclear Information System (INIS)

    In XFEL/SPring-8, it requires ultrashort electron bunches and their transportation to the undulator section. For the stable SASE operation, we have been developing three-dimensional femto-second bunch shape monitor based on Electro-Optic detection as non-destructive real-time single-shot measurements. We utilize a supercontinuum laser pulse with more than 400 nm bandwidth and an organic EO material for femto-second temporal resolution and radially polarized hollow laser beam for the three-dimensional measurements. We report the details of the concept and numerical estimations of this bunch shape monitor and developing status for the components of this monitor. (author)

  5. Electro-optical Bunch Length Monitor for FLUTE: Layout and Simulations

    OpenAIRE

    Borysenko, A.; Hertle, E.; Schuh, M.; Schwarz, M.; Wesolowski, P.; Steffen, Bernd; Hiller, N.; Judin, V.; Kehrer, B.; Marsching, S.; Müller, A. -S.; Nasse, M. J.; Rossmanith, R.; Ruprecht, R.

    2014-01-01

    A new compact linear accelerator FLUTE is currently under construction at Karlsruhe Institute of Technology (KIT) in collaboration with DESY and PSI. It aims at obtaining femtosecond electron bunches (~1fs - 300 fs) with a wide charge range (1 pC - 3 nC) and requires a precise bunch length diagnostic system. Here we present the layout of a bunch length monitor based on the electro-optic technique of spectral decoding using an Yb-doped fiber laser system (central wavelength 1030 nm) and a GaP ...

  6. Build up of Electron Cloud with Different Bunch Pattern in the Presence of Solenoid Field

    International Nuclear Information System (INIS)

    We have augmented the code POSINST to include solenoid fields, and used it to simulate the build up of electron cloud due to electron multipacting in the PEP-II positron ring. We find that the distribution of electrons is strongly affected by the resonances associated with the cyclotron period and bunch spacing. In addition, we discover a threshold beyond which the electron density grows exponentially until it reaches the space charge limit. The threshold does not depend on the bunch spacing but does depend on the positron bunch population

  7. 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

  8. 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.

  9. Generation and characterization of electron bunches with ramped current profile at the FLASH facility

    Energy Technology Data Exchange (ETDEWEB)

    Piot, P.; /Northern Illinois U. /Fermilab; Behrens, C.; Gerth, C.; /DESY; Lemery, F.; /Northern Illinois U.; Mihalcea, D.; /Fermilab; Vogt, M.; /DESY

    2011-09-01

    We report on the successful generation of electron bunches with current prof les that have a quasi-linear dependency on the longitudinal coordinate. The technique relies on impressing nonlinear correlations in the longitudinal phase space using a linac operating at two frequencies (1.3 and 3.9 GHz) and a bunch compressor. Data taken for various accelerator settings demonstrate the versatility of the method. The produced bunches have parameters well matched to drive high-gradient accelerating field with enhanced transformer ratio in beam-driven accelerators based on sub-mm-sizes dielectric or plasma structures.

  10. Generation of proton bunches by ultra-short laser pulses with high contrast

    International Nuclear Information System (INIS)

    Laser accelerated ion or proton bunches offer advantages compared to those generated by conventional accelerators, like better emittance and shorter pulse duration. We present our results on the acceleration of proton/ ion bunches created by ultra-short laser pulses of ultra-thin (d 12. It is shown how the features of the proton/ ion bunches depend on the laser pulse parameters, like intensity and contrast of the laser pulse. The results are discussed on the base of analytical calculation and PIC simulations.

  11. Experiment and simulations of sub-ps electron bunch train generation at Fermilab photoinjectors

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Y.-E; Church, M.; /Fermilab; Piot, P.; Prokop, C.R.; /Fermilab /Northern Illinois U.

    2011-10-01

    Recently the generation of electron bunch trains with sub-picosecond time structure has been experimentally demonstrated at the A0 photoinjector of Fermilab using a transverse-longitudinal phase-space exchange beamline. The temporal profile of the bunch train can be easily tuned to meet the requirements of the applications of modern accelerator beams. In this paper we report the A0 bunch-train experiment and explore numerically the possible extension of this technique to shorter time scales at the Fermilab SRF Accelerator Test Facility, a superconducting linear electron accelerator currently under construction in the NML building.

  12. 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.

  13. Quantum Linear Gravity in de Sitter Universe II: On Bunch-Davies vacuum state

    CERN Document Server

    Takook, M V

    2015-01-01

    In de Sitter ambient space formalism, the linear gravity can be written in terms of a minimally coupled scalar field and a polarization tensor. In this formalism, the minimally coupled massless scalar field can be quantized on Bunch-Davies vacuum state, that preserves the de Sitter invariant, the analyticity and removes the infrared divergence. The de Sitter quantum linear gravity is then constructed on Bunch-Davis vacuum state, which is also covariant, analytic and free of any infrared divergence. We conclude that the unique Bunch-Davies vacuum states can be used for construction of quantum field theory in de Sitter universe.

  14. Measurements of Bunch Motion Due to the Longitudinal Dipole-Coupled Bunch Instability at the Cornell Electron-Positron Storage Ring

    International Nuclear Information System (INIS)

    In the past a longitudinal dipole-coupled bunch instability had limited high current operation at CESR and resulted in a degradation of luminosity performance. A longitudinal feedback system successfully damps this instability and the exchange of superconducting rf cavities for normal conducting rf cavities in CESR has further reduced the instability's strength. A description of the longitudinal dynamics with the instability present are described in this paper along with detailed measurements of the instability using a dual-axis synchroscan streak camera. The measurements were made on single trains of bunches, multiple trains, and colliding beams. These measurements give a characterization of the instability's degradation of luminosity, modes of oscillation, and bunch distribution changes

  15. 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.

  16. 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

  17. Measurement of Sub-Picosecond Electron Bunches via Electro-Optic Sampling of Coherent Transition Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, Timothy John [Northern Illinois U.

    2012-01-01

    Future collider applications as well as present high-gradient laser plasma wakefield accelerators and free-electron lasers operating with picosecond bunch durations place a higher demand on the time resolution of bunch distribution diagnostics. This demand has led to significant advancements in the field of electro-optic sampling over the past ten years. These methods allow the probing of diagnostic light such as coherent transition radiation or the bunch wakefields with sub-picosecond time resolution. We present results on the single-shot electro-optic spectral decoding of coherent transition radiation from bunches generated at the Fermilab A0 photoinjector laboratory. A longitudinal double-pulse modulation of the electron beam is also realized by transverse beam masking followed by a transverse-to-longitudinal phase-space exchange beamline. Live profile tuning is demonstrated by upstream beam focusing in conjunction with downstream monitoring of single-shot electro-optic spectral decoding of the coherent transition radiation.

  18. Electron bunch profile reconstruction based on phase-constrained iterative algorithm

    Science.gov (United States)

    Bakkali Taheri, F.; Konoplev, I. V.; Doucas, G.; Baddoo, P.; Bartolini, R.; Cowley, J.; Hooker, S. M.

    2016-03-01

    The phase retrieval problem occurs in a number of areas in physics and is the subject of continuing investigation. The one-dimensional case, e.g., the reconstruction of the temporal profile of a charged particle bunch, is particularly challenging and important for particle accelerators. Accurate knowledge of the longitudinal (time) profile of the bunch is important in the context of linear colliders, wakefield accelerators and for the next generation of light sources, including x-ray SASE FELs. Frequently applied methods, e.g., minimal phase retrieval or other iterative algorithms, are reliable if the Blaschke phase contribution is negligible. This, however, is neither known a priori nor can it be assumed to apply to an arbitrary bunch profile. We present a novel approach which gives reproducible, most-probable and stable reconstructions for bunch profiles (both artificial and experimental) that would otherwise remain unresolved by the existing techniques.

  19. 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

  20. Short electron bunch generation using single-cycle ultrafast electron guns

    Science.gov (United States)

    Fallahi, Arya; Fakhari, Moein; Yahaghi, Alireza; Arrieta, Miguel; Kärtner, Franz X.

    2016-08-01

    We introduce a solution for producing ultrashort (˜fs ) high charge (˜pC ) from ultracompact guns utilizing single-cycle THz pulses. We show that the readily available THz pulses with energies as low as 20 μ J are sufficient to generate multi-10 keV electron bunches. Moreover, it is demonstrated that THz energies of 2 mJ are sufficient to generate relativistic electron bunches with higher than 2 MeV energy. The high acceleration gradients possible in the structures provide 30 fs electron bunches at 30 keV energy and 45 fs bunches at 2 MeV energy. These structures will underpin future devices for strong field THz physics in general and miniaturized electron guns, in which the high fields combined with the short pulse duration enable electron beams with ultrahigh brightness.

  1. Design of a High-bunch-charge 112-MHz Superconducting RF Photoemission Electron Source

    CERN Document Server

    Xin, T; Belomestnykh, Sergey A; Ben-Zvi, I; Boulware, C H; Grimm, T L; Hayes, T; Litvinenko, Vladimir N; Mernick, K; Narayan, G; Orfin, P; Pinayev, I; Rao, T; Severino, F; Skaritka, J; Smith, K; Than, R; Tuozzolo, J; Wang, E; Xiao, B; Xie, H; Zaltsman, A

    2016-01-01

    High-bunch-charge photoemission electron-sources operating in a continuous wave (CW) mode are required for many advanced applications of particle accelerators, such as electron coolers for hadron beams, electron-ion colliders, and free-electron lasers (FELs). Superconducting RF (SRF) has several advantages over other electron-gun technologies in CW mode as it offers higher acceleration rate and potentially can generate higher bunch charges and average beam currents. A 112 MHz SRF electron photoinjector (gun) was developed at Brookhaven National Laboratory (BNL) to produce high-brightness and high-bunch-charge bunches for the Coherent electron Cooling Proof-of-Principle (CeC PoP) experiment. The gun utilizes a quarter-wave resonator (QWR) geometry for assuring beam dynamics, and uses high quantum efficiency (QE) multi-alkali photocathodes for generating electrons.

  2. 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.

  3. Studies on an S-band bunching system with hybrid buncher

    International Nuclear Information System (INIS)

    Generally, a standard bunching system is composed by an SW pre-buncher, a TW buncher and a standard accelerating section. However, there is one way to simplify the whole system to some extent by using the hybrid buncher, which is a combined structure of the SW pre-buncher and the TW buncher. Here the beam dynamics studies on an S-band bunching system with the hybrid buncher is presented, and simulation results show that similar beam performance can be obtained at the linac exit by using this kind of bunching system rather than the standard one. In the meantime, the structure design of the hybrid buncher is also described. Furthermore, the standard accelerating section can also be integrated with the hybrid buncher, which can further simplify the usual bunching system and lower the construction cost. (authors)

  4. Electro Optic Bunch Length Measurements at the VUV-FEL at DESY

    CERN Document Server

    Steffen, Bernd; Knabbe, Ernst-Axel; Schlarb, Holger; Schmidt, Bernhard; Schmüser, Peter; Winter, Axel

    2005-01-01

    For the operation of a SASE FEL, the longitudinal bunch profile is one of the most critical parameters. At the superconducting linac of the VUV-FEL at DESY, an electro optic sampling (EOS) experiment was installed to probe the time structure of the electric field of the bunches to better than 100 fs rms. The field induced birefringence of a ZnTe crystal is detected by a femtosecond laser pulse (TiSa) and the time structure is measured by scanning the relative timing of the electron bunch and the TiSa pulse. A synchronization stability of better than 70 fs between laser and accelerator RF has been achieved. First results on the synchronization and the bunch profile measurements are presented.

  5. Electro-optical measurement of sub-ps structures in low charge electron bunches

    Science.gov (United States)

    Müller, F.; Peier, P.; Schlott, V.; Steffen, B.; Feurer, T.; Kuske, P.

    2012-07-01

    Electro-optical detection of THz coherent synchrotron radiation is a nondestructive method for measuring subpicosecond electron bunches or subpicosecond substructures on otherwise longer electron bunches. With a new diagnostic setup at the Swiss Light Source, which combines an amplified Yb fiber laser and a suitable GaP crystal, we demonstrate sampling as well as spectrally resolved single-shot measurements of sliced electron bunches containing as little as a few pC of charge. The single-shot measurements not only allow for a precise electric field characterization but also for a detailed analysis of the timing jitter between the electron bunch and the synchronized Yb fiber laser. The measurements of subsequent turns in the storage ring show distinct deviations from the simulations and we find strong indications that this discrepancy is caused by radiation loss through coherent synchrotron radiation itself, which is not included in many of today’s simulation codes.

  6. Method for the determination of the three-dimensional structure of ultrashort relativistic electron bunches

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, Gianluca; Ilinski, Petr; Saldin, Evgeni; Schneidmiller, Evgeni; Yurkov, Mikhail

    2009-05-15

    We describe a novel technique to characterize ultrashort electron bunches in Xray Free-Electron Lasers. Namely, we propose to use coherent Optical Transition Radiation to measure three-dimensional (3D) electron density distributions. Our method relies on the combination of two known diagnostics setups, an Optical Replica Synthesizer (ORS) and an Optical Transition Radiation (OTR) imager. Electron bunches are modulated at optical wavelengths in the ORS setup.When these electron bunches pass through a metal foil target, coherent radiation pulses of tens MW power are generated. It is thereafter possible to exploit advantages of coherent imaging techniques, such as direct imaging, diffractive imaging, Fourier holography and their combinations. The proposed method opens up the possibility of real-time, wavelength-limited, single-shot 3D imaging of an ultrashort electron bunch. (orig.)

  7. Optical synchronization and electron bunch diagnostic at the quasi-cw accelerator ELBE

    Energy Technology Data Exchange (ETDEWEB)

    Kuntzsch, Michael [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Technische Univ. Dresden (Germany); Lehnert, Ulf; Roeser, Fabian [Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany); Czwalinna, Marie Kristin; Schulz, Sebastian; Schlarb, Holger; Vilcins, Silke [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2013-07-01

    The continuous wave electron accelerator ELBE is upgraded to generate short and highly charged electron bunches (200 fs duration, up to 1 nC) with an energy of up to 40 MeV. In the last years a prototype of an optical synchronization system using a mode locked fiber laser has been build up which is now in commissioning phase. The stabilized pulse train can be used for new methods of electron bunch diagnostics like bunch arrival time measurement with the resolution down to a few femtoseconds. At ELBE a bunch arrival time monitor (BAM) has been designed and tested at the accelerator. The contribution shows the concept of the femtosecond synchronization system, the design of the BAM and first measurement results.

  8. Semiclassical quantization of the diamagnetic hydrogen atom with near-action-degenerate periodic-orbit bunches.

    Science.gov (United States)

    Gehrke, Jan; Main, Jörg; Wunner, Günter

    2010-12-01

    The existence of periodic orbit bunches is proven for the diamagnetic Kepler problem. Members of each bunch are reconnected differently at self-encounters in phase space but have nearly equal classical action and stability parameters. Orbits can be grouped already on the level of the symbolic dynamics by application of appropriate reconnection rules to the symbolic code in the ternary alphabet. The periodic orbit bunches can significantly improve the efficiency of semiclassical quantization methods for classically chaotic systems, which suffer from the exponential proliferation of orbits. For the diamagnetic hydrogen atom the use of one or few representatives of a periodic orbit bunch in Gutzwiller's trace formula allows for the computation of semiclassical spectra with a classical data set reduced by up to a factor of 20. PMID:21230723

  9. Short Electron Bunch Generation Using Single-Cycle Ultrafast Electron Guns

    CERN Document Server

    Fallahi, Arya; Yahaghi, Alireza; Arrieta, Miguel; Kärtner, Franz X

    2016-01-01

    We introduce a solution for producing ultrashort ($\\sim$fs) high charge ($\\sim$pC) from ultra-compact guns utilizing single-cycle THz pulses. We show that the readily available THz pulses with energies as low as 20 ?J are sufficient to generate multi-10 keV electron bunches. Moreover, It is demonstrated that THz energies of 2mJ are sufficient to generate relativistic electron bunches with higher than 2 MeV energy. The high acceleration gradients possible in the structures provide 30 fs electron bunches at 30 keV energy and 45 fs bunches at 2 MeV energy. These structures will underpin future devices for strong field THz physics in general and miniaturized electron guns, in which the high fields combined with the short pulse duration enable electron beams with ultrahigh brightness.

  10. Synthesis and Electrochemical Sensing Toward Heavy Metals of Bunch-like Bismuth Nanostructures

    Science.gov (United States)

    Zhang, Zhi; Yu, Ke; Bai, Dan; Zhu, Ziqiang

    2010-02-01

    Large-scale bunch-like bismuth (Bi) nanostructures were the first time to be synthesized via two-step electrochemical deposition. The growth mechanism of the nanostructures was discussed. Such a designed bunch-like Bi electrode has high sensitivity to detect the heavy metal ions due to its unique three-dimensional structures and strong ability of adsorbing the heavy metal ions. The bunch-like Bi electrode’s detection of heavy metals was statically performed using anodic stripping voltammetry (ASV). The detection in the Pb(II) concentration range of 2.5-50 μg/l was also performed. Based on the experimental results, this bunch-like Bi electrode can be considered as an interesting alternative to common mercury electrodes and bismuth film electrodes for possible use in electrochemical studies and electroanalytical applications.

  11. Measurements of Compression and Emittance Growth after the First LCLS Bunch Compressor Chicane

    International Nuclear Information System (INIS)

    The Linac Coherent Light Source (LCLS) is a SASE xray free-electron laser project presently under construction at SLAC. The injector section from RF photocathode gun through first bunch compressor chicane was installed during the fall of 2006. The first bunch compressor is located at 250 MeV and nominally compresses a 1-nC electron bunch from an rms length of about 1 mm to 0.2 mm. Transverse phase space and bunch length diagnostics are located immediately after the chicane. We present preliminary measurements and simulations of the longitudinal and transverse phase space after the chicane in various beam conditions, including extreme compression with micron-scale current spikes

  12. Construction and performance of the magnetic bunch compressor for the THz facility at Chiang Mai University

    International Nuclear Information System (INIS)

    The Plasma and Beam Physics Research Facility at Chiang Mai University has established a THz facility to focus on the study of ultra-short electron pulses. Short electron bunches can be generated from a system that consists of a radio-frequency (RF) gun with a thermionic cathode, an alpha magnet as a magnetic bunch compressor, and a linear accelerator as a post-acceleration section. The alpha magnet is a conventional and simple instrument for low-energy electron bunch compression. With the alpha magnet constructed in-house, several hundred femtosecond electron bunches for THz radiation production can be generated from the thermionic RF gun. The construction and performance of the alpha magnet, as well as some experimental results, are presented in this paper.

  13. Calculation of seed values for longitudinal coupled bunch dipole instability due to uneven bucket population

    International Nuclear Information System (INIS)

    Conventionally, the starting amplitude (or 'seed') for bunched beam coherent oscillations is assumed independent of the steady state Fourier components of the beam, and is attributed to imperfect technology of randomness. However, there are occasions when the dominant component of the seeds derive from the transient response of the impedance to the revolution harmonics. Such harmonics are caused by uneven bucket population. In this paper we find the beam response to sweeping the radio frequency through a cavity parasitic resonance in order to calculate the increases in the individual bunch dipole moments and the coupled-bunch oscillation amplitude. In the KAON Booster, an hypothetical first HOM with Q = 4000 and R/Q = 30 gives a coupled-bunch dipole oscillation of 27 degrees of rf phase; which would swamp any injection timing errors. (Author) 4 refs

  14. 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.

  15. 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.

  16. 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.

  17. Preliminary result of bunch length measurement using a modified Michelson interferometer

    Institute of Scientific and Technical Information of China (English)

    LIN Xu-Ling; ZHANG Jian-Bing; LUO Feng; BEI Hua; LU Shan-Liang; YU Tie-Min; DAI Zhi-Min

    2009-01-01

    Based on the femtosecond accelerator device which was built at the Shanghai Institute of Applied Physics (SINAP), recently a modified far infrared Michelson interferometer has been developed to measure the length of electron bunches via the optical autocorrelation method.Compared with our former normal Michelson interferometer, we use a hollow retroreflector instead of a flat mirror as the reflective mirror.The experimental setup and results of the bunch length measurement will be described in this paper.

  18. A simple method for the determination of the structure of ultrashort relativistic electron bunches

    International Nuclear Information System (INIS)

    In this paper 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 simply the combination of two well-known techniques, which where not previously combined to our knowledge. We use seed 10-ps 1047 nm quantum laser to produce exact optical replica of ultrafast electron bunches. The replica is generated in apparatus which consists of an input undulator (energy modulator), and the short 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 100 MW-level peak power. We then use the now-standard method of ultrashort laser pulse-shape measurement. Fortunately, in the past five years, remarkable progress has occurred in the development of techniques for the measurement of ultrashort laser pulses. For example, a tandem combination of autocorrelator and spectrum (FROG - frequency resolved optical gating) can be used to extract shape information from ultrashort pulses. The FROG trace of ultrashort optical replica can be used to give accurate and rapid electron bunch shape measurements in a way similar to a femtosecond oscilloscope. Real-time single-shot measurements of the electron bunch structure could provide significant information about physical mechanisms responsible for generation ultrashort electron bunches in bunch compressors. The big advantage of proposed technique is that it can be used to determine the slice energy spread and emittance in multishot measurements. It is possible to measure bunch structure completely, that is to measure peak current, energy spread and transverse emittance as a function of time. We illustrate with numerical examples the potential of the proposed method for electron beam diagnostics at the European X-ray FEL. (orig.)

  19. Morphological and chemical nature of fiber strands of oil palm empty-fruit-bunch (OPEFB)

    OpenAIRE

    Wan Rosli Wan Daud; Kwei-Nam Law; Arniza Ghazali,

    2007-01-01

    In this work we examined the morphological and chemical characteristics of the fibrous strands of oil palm empty-fruit-bunch which were left behind after being stripped of their fruits used for oil production. The empty-fruit-bunches were mechanically loosened to yield the fibrous strands, which can be used in paper and board making. We found that the fibrous strands had unique structure by having several large-diameter, long vessel elements in their core region, surrounded by vascular fibers...

  20. A method for calculating longitudinal phase space distribution when given the time profile of the bunch

    Energy Technology Data Exchange (ETDEWEB)

    Cheng-Yang Tan

    2001-07-30

    We will show in this paper a method for calculating the longitudinal phase space distribution when the time profile of the bunch as measured by a wall current monitor is given. The key to this method is the assumption that the bunch is matched to the bucket. With this assumption, we will show that the method boils down to solving a simple upper triangular matrix equation. We will also illustrate the method with two examples and show the method's shortcomings.

  1. On the computation of electromagnetic fields excited by relativistic bunches of charged particles in accelerating structures

    International Nuclear Information System (INIS)

    A numerical method is described for the calculaion of electromagnetic fields excited by arbitrarily shaped bunches of charged particles travelling through accelerating structures with cylindrical symmetry. The fields are computed by numerical integration of Maxwell's equations in the time domain. The computer program based on this method enables the user to calculate transient electromagnetic fields as well as the energy gain of particles inside the bunch. Some results are given for the LEP cavity and a pillbox. (orig.)

  2. Evaluation of fungicide programs for management of Botrytis bunch rot of grapes: 2009 field trial

    OpenAIRE

    Janousek, Christopher N; Bay, Ian S.; Herche, Ryan W; Gubler, W D

    2009-01-01

    Botrytis bunch rot is an important grapevine disease in California. Twenty eight fungicide programs were evaluated for control of bunch rot in a field experiment in a Chardonnay (clone 4) vineyard in the Carneros region of Napa Valley, California during 2009. Four fungicide applications were made from bloom to harvest with the final application made just prior to heavy rainfall. Disease was rated three weeks following the final application. Disease developed rapidly during the month of Octobe...

  3. Evaluation of fungicide programs for management of Botrytis bunch rot of grapes: 2010 field trial

    OpenAIRE

    Bay, Ian S.; Eynard, James; Gubler, W D

    2010-01-01

    Bunch rot of grapes is caused by Botrytis cinerea, a fast-growing pathogen infecting numerous crops of commercial value. Bunch rot can potentially lead to a reduction in the yield and quality of table, raisin, and wine grapes, with high economic losses in some locations or years (Flaherty et al. 1992). Botrytis overwinters as sclerotia in mummified berries on the ground or on canes. The disease can first appear as shoot blight following frequent spring rains; flowers can become infected durin...

  4. 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

  5. Feasibility of producing insulation boards from oil palm fronds and empty Fruit bunches

    OpenAIRE

    Tanasri Sihabut; Nikhom Laemsak

    2010-01-01

    This research focused on the feasibility of producing insulation boards made from oil palm fronds and empty fruit bunches via the wet forming process. Results confirmed no difference in the visual appearance between both board types. Both displayed low thermal conductivity, offering evidence of being good insulators. Boards made from empty fruit bunch weighed less than boards made from oil palm fronds. Other properties such as fire retardant, water absorption and strength still need to be inv...

  6. Feasibility of producing insulation boards from oil palm fronds and empty Fruit bunches

    Directory of Open Access Journals (Sweden)

    Tanasri Sihabut

    2010-03-01

    Full Text Available This research focused on the feasibility of producing insulation boards made from oil palm fronds and empty fruit bunches via the wet forming process. Results confirmed no difference in the visual appearance between both board types. Both displayed low thermal conductivity, offering evidence of being good insulators. Boards made from empty fruit bunch weighed less than boards made from oil palm fronds. Other properties such as fire retardant, water absorption and strength still need to be investigated.

  7. 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...

  8. 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...

  9. 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.)

  10. Wakefield Excitation by a Sequence of Electron Bunches in a Rectangular Waveguide Lined with Dielectric Slabs

    International Nuclear Information System (INIS)

    A rectangular dielectric-lined metallic structure was studied that has an advantage over a cylindrical structure from the possibility of exciting by a sequence of bunches many equally-spaced modes, thereby building up a larger mode-locked wakefield. A rectangular vacuum copper waveguide was lined with two dielectric slabs, the size of which was calculated to provide resonant excitation of the fundamental LSM mode by a sequence of bunches with repetition frequency f0=2805 MHz, produced by linear resonant electron accelerator (4.5 MeV, number of bunches 6.103, diameter 1cm, duration 60 ps each, distance between bunches 300 ps, number of electrons in each bunch 109). The waveguide has cross section 85 mm x 180 mm, and Teflon (ε 2.1) plates were placed along the smaller sides of the waveguide, their thickness from the calculation being 22 mm. In experiments, the length of the resonator was 535mm. We found that the total wakefield is three times larger than the fundamental mode; thus a greater number of excited modes was excited compared with the cylindrical case, for which this ratio was only 1.5. We found considerably more energy loss of electron bunches for the resonator case compared with the waveguide case

  11. Temporal characterization of ultrashort linearly chirped electron bunches generated from a laser wakefield accelerator

    Science.gov (United States)

    Zhang, C. J.; Hua, J. F.; Wan, Y.; Guo, B.; Pai, C.-H.; Wu, Y. P.; Li, F.; Chu, H.-H.; Gu, Y. Q.; Mori, W. B.; Joshi, C.; Wang, J.; Lu, W.

    2016-06-01

    A new method for diagnosing the temporal characteristics of ultrashort electron bunches with linear energy chirp generated from a laser wakefield accelerator is described. When the ionization-injected bunch interacts with the back of the drive laser, it is deflected and stretched along the direction of the electric field of the laser. Upon exiting the plasma, if the bunch goes through a narrow slit in front of the dipole magnet that disperses the electrons in the plane of the laser polarization, it can form a series of bunchlets that have different energies but are separated by half a laser wavelength. Since only the electrons that are undeflected by the laser go through the slit, the energy spectrum of the bunch is modulated. By analyzing the modulated energy spectrum, the shots where the bunch has a linear energy chirp can be recognized. Consequently, the energy chirp and beam current profile of those bunches can be reconstructed. This method is demonstrated through particle-in-cell simulations and experiment.

  12. 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

  13. 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

  14. AGS new fast extraction system and the single bunch extraction test

    Energy Technology Data Exchange (ETDEWEB)

    Weng, W.T.

    1983-01-01

    For the neutrino physics program and for the CBA injection, a new fast extraction system has been implemented to improve the extraction efficiency and the quality of the extracted beam. Central to the new system is a new fast kicker, placed at the H5 straight section, capable of rising between bunches, t/sub r/ < 170 nsec, and staying constant for 2.6 ..mu..sec with flat top ripple less than +-1.5%. So far, the system has been operated for longer than 3000 hours and routinely extracts 10/sup 13/ ppp at 99% efficiency. Experiment 745 on QCD test requires a single AGS bunch of 40 nsec. For this purpose another fast kicker was placed at the E5 straight section and powered by a new pulser to produce a half sinusoidal pulse with both a rise and fall time of 200 nsec. A single AGS bunch was extracted through the slow beam channel at 22 GeV/c leaving the remaining 11 bunches undisturbed which continued to be accelerated to 29.4 GeV/c and extracted by the H5 kicker through the fast beam channel. Because the ring circumference ratio of CBA to the AGS is 4-3/4, some of the injected beam from the AGS has to contain 11 bunches instead of 12; consequently, this single bunch extraction mode will also be used for CBA injection.

  15. Exploiting coherence for real-time studies by single-bunch imaging

    Energy Technology Data Exchange (ETDEWEB)

    Rack, A., E-mail: arack@snafu.de; Scheel, M.; Hardy, L.; Curfs, C.; Bonnin, A.; Reichert, H. [European Synchrotron Radiation Facility, 38000 Grenoble Cedex (France)

    2014-05-09

    First real-time studies of ultra-fast processes by means of a single-bunch imaging technique at the European Synchrotron Radiation Facility are reported. Both absorption contrast and phase contrast are accessible thanks to propagation distances of several metres. First real-time studies of ultra-fast processes by single-bunch imaging at the European Synchrotron Radiation Facility are reported. By operating the storage ring of the ESRF in single-bunch mode with its correspondingly increased electron bunch charge density per singlet, the polychromatic photon flux density at insertion-device beamlines is sufficient to capture hard X-ray images exploiting the light from a single bunch (the corresponding bunch length is 140 ps FWHM). Hard X-ray imaging with absorption contrast as well as phase contrast in combination with large propagation distances is demonstrated using spatial samplings of 11 µm and 35 µm pixel size. The images acquired allow one to track crack propagation in a bursting piece of glass, breaking of an electrical fuse as well as cell wall rupture in an aqueous foam. Future developments and their potential in the frame of the proposed Phase II of the ESRF Upgrade Program are discussed.

  16. Self-pinching of a relativistic electron bunch in a drift tube

    CERN Document Server

    Parazzoli, C G; Parazzoli, Claudio G.; Koltenbah, Benjamin E.C.

    1997-01-01

    Electron bunches with charge densities $\\rho$ of the order of $10^2$ to $10^3$ [nC/cm$^3$], energies between $20.$ and $100.$ [MeV], peak current $>100$ [A], bunch lengths between 0.3 and 1.8 [cm], and bunch charge of 2.0 to $20.$ [nC] are relevant to the design of Free Electron Lasers and future linear colliders. In this paper we present the results of numerical simulations performed with a particle in a cell (pic) code of an electron bunch in a drift tube. The electron bunch has cylindrical symmetry with the $z$-axis oriented in the direction of motion. The charge density distribution is constant in the radial and Gaussian in the longitudinal direction, respectively. The electron bunch experiences both a radial pinch in the middle of the pulse, corresponding to the peak electron density, and a significant growth of the correlated emittance. This behavior is explained, and an approximate scaling law is identified. Comparisons of the results from the pic and PARMELA codes are presented.

  17. Exploiting coherence for real-time studies by single-bunch imaging

    International Nuclear Information System (INIS)

    First real-time studies of ultra-fast processes by means of a single-bunch imaging technique at the European Synchrotron Radiation Facility are reported. Both absorption contrast and phase contrast are accessible thanks to propagation distances of several metres. First real-time studies of ultra-fast processes by single-bunch imaging at the European Synchrotron Radiation Facility are reported. By operating the storage ring of the ESRF in single-bunch mode with its correspondingly increased electron bunch charge density per singlet, the polychromatic photon flux density at insertion-device beamlines is sufficient to capture hard X-ray images exploiting the light from a single bunch (the corresponding bunch length is 140 ps FWHM). Hard X-ray imaging with absorption contrast as well as phase contrast in combination with large propagation distances is demonstrated using spatial samplings of 11 µm and 35 µm pixel size. The images acquired allow one to track crack propagation in a bursting piece of glass, breaking of an electrical fuse as well as cell wall rupture in an aqueous foam. Future developments and their potential in the frame of the proposed Phase II of the ESRF Upgrade Program are discussed

  18. Spectral reflectance of oil-palm (Elaeis guineensis Jacq. bunches as indicator for optimal harvesting

    Directory of Open Access Journals (Sweden)

    Wunsri, S.

    2005-12-01

    Full Text Available To determine the appropriate harvesting time of Tenera oil palm bunches, the spectral reflectance of ripening bunches was investigated from images taken by a digital Canon PowerShot A20 camera. Every second day images were taken from selected bunches at an oil-palm estate during the growth of the bunchesfrom immaturity to the over-ripe phase, to trace the changes in color which correlate with the process of ripening. The images were analyzed measuring the changes in the three basic colors red, green and blue, using a specially developed Color Analysis computer program for Oil-palm 'fruit' (CAOP, and determining the correlation with the measured palm-oil content of the nuts.Of the three color-bands, the red light reflectance showed the best correlation with ripeness, as the red color increased regularly and practically linearly up to the stage of the maximal oil yield. Some seven days after the thus determined optimal harvesting date for the ripe bunches, some of the ripe nuts will detachfrom the bunch and fall, but then it is too late to use the fallen nuts as indicators for harvesting. From our investigations in the field and in the laboratory we recommend that harvesting should follow immediately after the red reflectance starts declining, after having reached its peak value for the Tenera oil-palm some 5±3 days before nuts begin to detach from the bunch.

  19. A robust fibre laser system for electro-optic electron bunch profile measurements at FLASH

    International Nuclear Information System (INIS)

    For the electro-optic measurement of electron bunch profiles at FLASH a robust ytterbium doped fibre laser (YDFL) system has been developed consisting of a laser oscillator and a two-staged amplifier. The oscillator is designed to meet the specifications of high reliability and low noise operation. The amplifier makes use of tailored nonlinearity to enhance the spectral bandwidth of the output laser pulses. Active repetition rate control enables sub-picosecond synchronisation of the laser to the accelerator reference RF. Using a two-stage gating scheme the output pulse train repetition rate is adopted to the accelerator repetition rate. An experimental site used for electro-optic electron bunch diagnostics has been redesigned to support single-shot bunch profile measurements based on spectral decoding. An existing bunch profile monitor with a similar laser system was upgraded and electro-optic bunch profile measurements were conducted, allowing for a comparison with measurements done with other longitudinal electron bunch diagnostics and with former measurements.

  20. A robust fibre laser system for electro-optic electron bunch profile measurements at FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Wissmann, Laurens-Georg

    2012-08-15

    For the electro-optic measurement of electron bunch profiles at FLASH a robust ytterbium doped fibre laser (YDFL) system has been developed consisting of a laser oscillator and a two-staged amplifier. The oscillator is designed to meet the specifications of high reliability and low noise operation. The amplifier makes use of tailored nonlinearity to enhance the spectral bandwidth of the output laser pulses. Active repetition rate control enables sub-picosecond synchronisation of the laser to the accelerator reference RF. Using a two-stage gating scheme the output pulse train repetition rate is adopted to the accelerator repetition rate. An experimental site used for electro-optic electron bunch diagnostics has been redesigned to support single-shot bunch profile measurements based on spectral decoding. An existing bunch profile monitor with a similar laser system was upgraded and electro-optic bunch profile measurements were conducted, allowing for a comparison with measurements done with other longitudinal electron bunch diagnostics and with former measurements.