WorldWideScience

Sample records for bunching

  1. 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

  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 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)

  3. 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)

  4. 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)

  5. 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.

  6. 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.

  7. 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.

  8. 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)

  9. 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

  10. 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.

  11. Non-Intercepting Bunch Length Monitor for Picosecond Electron Bunches

    CERN Document Server

    Braun, Hans Heinrich

    1998-01-01

    A bunch length monitor for very short electron bunches, r.m.s. > 1 ps, has been implemented in the CLIC (Compact Linear Collider) Test Facility (CTF) at CERN. It consists of a long, rectangular wavegu ide connected at one end to the beam pipe and a detection system at the other end. Information on the bunch length is obtained by frequency-domain analysis of the signal excited by the beam in the wav eguide. The signal can be detected either by a fast diode detector or by a RF mixer in combination with a RF sweep oscillator. With the diode detector, single-shot measurements can be performed, while the mixer set-up allows quantitative bunch length measurements for single bunches and for bunch-trains. The design and installation of two monitors and detection systems operating in two different fre quency bands, Ka (26.5--40 GHz) and E (60--90 GHz), are described. Results obtained with the new monitor are presented and compared with bunch length measurements that were performed simultaneously wi th a streak camera ...

  12. 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)

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

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

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

  14. Overview of bunch length measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A. H.

    1999-02-19

    An overview of particle and photon beam bunch length measurements is presented in the context of free-electron laser (FEL) challenges. Particle-beam peak current is a critical factor in obtaining adequate FEL gain for both oscillators and self-amplified spontaneous emission (SASE) devices. Since measurement of charge is a standard measurement, the bunch length becomes the key issue for ultrashort bunches. Both time-domain and frequency-domain techniques are presented in the context of using electromagnetic radiation over eight orders of magnitude in wavelength. In addition, the measurement of microbunching in a micropulse is addressed.

  15. 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.

  16. 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...

  17. 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

  18. 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

  19. 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.

  20. 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

  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. 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...

  3. 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

  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. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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)

  13. 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

  14. 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.

  15. 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)

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  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. 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

  7. Bucket shaking stops bunch dancing in Tevatron

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-03-01

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

  8. Bucket shaking stops bunch dancing in Tevatron

    International Nuclear Information System (INIS)

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

  9. 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

  10. 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

  11. 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.

  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. 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

  14. 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.

  15. 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...

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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...

  2. 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.

  3. 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

  4. 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

  5. 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.

  6. 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

  7. Use of Helical Transport Channels for Bunch Recombination

    Energy Technology Data Exchange (ETDEWEB)

    Neuffer, David; Yonehara, Katsuya; /Fermilab; Yoshikawa, Cary; /MUONS Inc., Batavia

    2010-03-01

    Cooling scenarios for a high-luminosity Muon Collider require bunch recombination for optimal luminosity. In this report we note that the tunable chronicity property of a helical transport channel (HTC) makes it a desirable component of a bunch recombiner. A large chronicity HTC is desirable for the bunch recombining transport, while more isochronous transport may be preferred for rf manipulations. Scenarios for bunch recombination are presented, with initial 1-D simulations, in order to set the stage for future 3-D simulation and optimization. HTC transports may enable a very compact bunch recombiner.

  8. Use of Helical Transport Channels for Bunch Recombination

    Energy Technology Data Exchange (ETDEWEB)

    Neuffer, David; Yonehara, Katsuya; /Fermilab; Ankenbrandt, C.; Yoshikawa, Cary; /MUONS Inc., Batavia

    2012-05-01

    Cooling scenarios for a high-luminosity Muon Collider require bunch recombination for optimal luminosity. In this report we note that the tunable chronicity property of a helical transport channel (HTC) makes it a desirable component of a bunch recombiner. A large chronicity HTC is desirable for the bunch recombining transport, while more isochronous transport may be preferred for rf manipulations. Scenarios for bunch recombination are presented, with initial 1-D simulations, in order to set the stage for future 3-D simulation and optimization. HTC transports may enable a very compact bunch recombiner.

  9. 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)

  10. 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.

  11. Halo formation in three-dimensional bunches

    Energy Technology Data Exchange (ETDEWEB)

    Gluckstern, R.L.; Fedotov, A.V. [Physics Department, University of Maryland, College Park, Maryland 20742 (United States); Kurennoy, S.; Ryne, R. [Los Alamos Neutron Science Center Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    1998-10-01

    We have constructed, analytically and numerically, a class of self-consistent six-dimensional (6D) phase space stationary distributions. Stationary distributions allow us to study the halo development mechanism without it being obscured by beam redistribution and its effect on halo formation. The beam is then mismatched longitudinally and/or transversely, and we explore the formation of longitudinal and transverse halos in 3D axisymmetric beam bunches. We find that the longitudinal halo forms first for comparable longitudinal and transverse mismatches because the longitudinal tune depression is more severe than the transverse one for elongated bunches. Of particular importance is the result that, due to the coupling between longitudinal and transverse motion, a longitudinal or transverse halo is observed for a mismatch less than 10{percent} if the mismatch in the other plane is large. {copyright} {ital 1998} {ital The American Physical Society}

  12. Halo formation in three-dimensional bunches

    CERN Document Server

    Fedotov, A V; Kurennoy, S S; Ryne, Robert D

    1998-01-01

    A new class of self-consistent 6-D phase space stationary distributions is constructed both analytically and numerically. The beam is then mismatched longitudinally and/or transversely, and we explore the beam stability and halo formation for the case of 3-D axisymmetric beam bunches using particle-in-cell simulations. We concentrate on beams with bunch length-to-width ratios varying from 1 to 5, which covers the typical range of the APT linac parameters. We find that the longitudinal halo forms first for comparable longitudinal and transverse mismatches. An interesting coupling phenomenon - a longitudinal or transverse halo is observed even for very small mismatches if the mismatch in the other plane is large - is discovered.

  13. Halo formation in three-dimensional bunches

    Science.gov (United States)

    Gluckstern, R. L.; Fedotov, A. V.; Kurennoy, S.; Ryne, R.

    1998-10-01

    We have constructed, analytically and numerically, a class of self-consistent six-dimensional (6D) phase space stationary distributions. Stationary distributions allow us to study the halo development mechanism without it being obscured by beam redistribution and its effect on halo formation. The beam is then mismatched longitudinally and/or transversely, and we explore the formation of longitudinal and transverse halos in 3D axisymmetric beam bunches. We find that the longitudinal halo forms first for comparable longitudinal and transverse mismatches because the longitudinal tune depression is more severe than the transverse one for elongated bunches. Of particular importance is the result that, due to the coupling between longitudinal and transverse motion, a longitudinal or transverse halo is observed for a mismatch less than 10% if the mismatch in the other plane is large.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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].

  19. 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...

  20. 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.

  1. 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.

  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. Responses of savanna lawn and bunch grasses to water limitation

    NARCIS (Netherlands)

    van der Plas, Alfons; Zeinstra, Patricia; Veldhuis, Michiel; Fokkema, Rienk; Tielens, Elske; Howison, Ruth; Olff, Han

    2013-01-01

    The grass layer of African savannas consists of two main vegetation types: grazing lawns, dominated by short, mostly clonally reproducing grasses, and bunch grasslands, dominated by tall bunch grasses. This patchy distribution of vegetation types is mostly created by large herbivores, which selectiv

  4. 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...

  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. Higher-order photon bunching in a semiconductor microcavity

    DEFF Research Database (Denmark)

    Assmann, M.; Veit, F.; Bayer, M.;

    2009-01-01

    in the single-mode emission of a semiconductor microcavity in the weak and strong coupling regimes. The counting statistics of single photons were recorded with picosecond time resolution, allowing quantitative measurement of the few-photon bunching inside light pulses. Our results show bunching behavior...

  7. Ultra short electron beam bunches from a laser plasma cathode

    Energy Technology Data Exchange (ETDEWEB)

    Maekawa, Akira [Nuclear Professional School, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan)]. E-mail: maekawa@nuclear.jp; Tsujii, Ryosuke [Nuclear Professional School, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Kinoshita, Kennichi [Nuclear Professional School, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Atsushi, Yamazaki [Nuclear Professional School, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Kobayashi, Kazuyuki [Nuclear Professional School, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Uesaka, Mitsuru [Nuclear Professional School, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Shibata, Yukio [Nuclear Professional School, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Kondo, Yasuhiro [Nuclear Professional School, University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Ohkubo, Takeru [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gunma (Japan); Hosokai, Tomonao [Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo (Japan); Zhidkov, Alexei [Central Research Institute of Electric Power Industry, 2-6-1 Nagasaka, Yokosuka, Kanagawa (Japan); Takahashi, Toshiharu [Kyoto University Research Reactor Institute, Asahiro-nishi2, Kumatori, Sennan, Osaka (Japan)

    2007-08-15

    The fluctuation of the electron bunch duration due to energy spectrum instability in a laser plasma cathode has been examined. Previous experiments clearly proved that a laser plasma cathode can generate ultrashort electron bunches with a bunch duration of 130 fs (FWHM) and a geometrical emittance 0.07{pi} mm mrad. The effect of temporal elongation of electron bunches due to their energy spread is estimated and the results are in good agreement with previous experiments. It is also clarified that the instability of the energy spectrum not only leads to a fluctuation of the bunch shape but also to a time-of-flight jitter, affecting possible future applications of a laser plasma cathode.

  8. Studies of RF Noise Induced Bunch Lengthening at the LHC

    CERN Document Server

    Mastoridis, T; Rivetta, C H; Baudrenghien, P; Butterworth, A C; Molendijk, J C

    2011-01-01

    Radio Frequency noise induced bunch lengthening can strongly affect the Large Hadron Collider performance through luminosity reduction, particle loss, and other effects. Models and theoretical formalisms demonstrating the dependence of the LHC longitudinal bunch length on the RF station noise spectral content have been presented*,**. Initial measurements validated these studies and determined the performance limiting RF components. For the existing LHC LLRF implementation the bunch length increases with a rate of 1 mm/hr, which is higher than the intrabeam scattering diffusion and leads to a 27% bunch length increase over a 20 hour store. This work presents measurements from the LHC that better quantify the relationship between the RF noise and longitudinal emittance blowup. Noise was injected at specific frequency bands and with varying amplitudes at the LHC accelerating cavities. The experiments presented in this paper confirmed the predicted effects on the LHC bunch length due to both the noise around the ...

  9. 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...

  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. 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.

  13. 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...

  14. 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.

  15. 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.

  16. 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

  17. Investigation of transient processes at the DELTA electron storage ring using a digital bunch-by-bunch feedback system

    International Nuclear Information System (INIS)

    At the 1.5-GeV synchrotron radiation source DELTA, operated by the TU Dortmund University, intensive synchrotron radiation in the spectral range from hard X-rays to THz radiation is generated by the circular deflection of highly relativistic electron bunches. Interacting with the vacuum chamber wall, the electron bunches create electric fields, which can act back on subsequent bunches. With increasing beam current, the excitation is enhanced so that the electron beam is unstable, which means that the electron bunches oscillate longitudinally or transversely relative to their reference position. The oscillations reduce the quality of the synchrotron radiation and limit the maximum storable beam current. Within the scope of this thesis, the beam instabilities at the storage ring were systematically investigated. A digital bunch-by-bunch feedback system was installed and commissioned, which allows to detect and digitize the position of each electron bunch at each turn. Based on the input signal, a correction signal is calculated in order to suppress transverse and longitudinal oscillation of the bunches. In addition, it is possible to excite dedicated bunches. The systematic excitation of all coupled-bunch modes allowed for the first time to determine the damping rates of all 192 eigenmodes of the electron beam. The current dependence of the damping rates was investigated and an instability threshold was found. Besides the investigation of multibunch instabilities, single-bunch instabilities are discussed. In addition, the acquisition unit of the digital feedback system can be triggered on external events. This was used to investigate the injection process and beam losses. It was shown that the transverse feedback system increases the injection efficiency. Another aspect of this thesis is the improvement of the signal quality of ultrashort coherent synchrotron radiation pulses, which are generated by the short-pulse facility at DELTA. The short-pulse facility is based

  18. Investigation of transient processes at the DELTA electron storage ring using a digital bunch-by-bunch feedback system

    Energy Technology Data Exchange (ETDEWEB)

    Hoener, Markus

    2015-07-01

    At the 1.5-GeV synchrotron radiation source DELTA, operated by the TU Dortmund University, intensive synchrotron radiation in the spectral range from hard X-rays to THz radiation is generated by the circular deflection of highly relativistic electron bunches. Interacting with the vacuum chamber wall, the electron bunches create electric fields, which can act back on subsequent bunches. With increasing beam current, the excitation is enhanced so that the electron beam is unstable, which means that the electron bunches oscillate longitudinally or transversely relative to their reference position. The oscillations reduce the quality of the synchrotron radiation and limit the maximum storable beam current. Within the scope of this thesis, the beam instabilities at the storage ring were systematically investigated. A digital bunch-by-bunch feedback system was installed and commissioned, which allows to detect and digitize the position of each electron bunch at each turn. Based on the input signal, a correction signal is calculated in order to suppress transverse and longitudinal oscillation of the bunches. In addition, it is possible to excite dedicated bunches. The systematic excitation of all coupled-bunch modes allowed for the first time to determine the damping rates of all 192 eigenmodes of the electron beam. The current dependence of the damping rates was investigated and an instability threshold was found. Besides the investigation of multibunch instabilities, single-bunch instabilities are discussed. In addition, the acquisition unit of the digital feedback system can be triggered on external events. This was used to investigate the injection process and beam losses. It was shown that the transverse feedback system increases the injection efficiency. Another aspect of this thesis is the improvement of the signal quality of ultrashort coherent synchrotron radiation pulses, which are generated by the short-pulse facility at DELTA. The short-pulse facility is based

  19. 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.

  20. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Gronbech-Jensen, N.; Samuelsen, M.R. (Physics Laboratory I, The Technical University of Denmark, DK-2800 Lyngby (Denmark)); Lomdahl, P.S. (Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM (USA)); Blackburn, J.A. (Department of Physics and Computing, Wilfrid Laurier University, Waterloo, Ontario (Canada))

    1990-09-01

    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.

  2. 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.

  3. 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

  4. Dependence of bunch energy loss in cavities on beam velocity

    Science.gov (United States)

    Kurennoy, Sergey S.

    1999-03-01

    Beam energy loss in a cavity can be easily computed for a relativistic bunch using time-domain codes like MAFIA or ABCI. However, for nonrelativistic beams the problem is more complicated because of difficulties with its numerical formulation in the time domain. We calculate the cavity loss factors for a bunch in frequency domain as a function of its velocity and compare results with the relativistic case.

  5. 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.

  6. MD 346: Summary of single bunch instability threshold measurements

    CERN Document Server

    Carver, Lee Robert; Metral, Elias; Salvant, Benoit; Levens, Tom; Buffat, Xavier; Pieloni, Tatiana; Tambasco, Claudia; Trad, Georges; CERN. Geneva. ATS Department

    2016-01-01

    The purpose of this MD is to measure the octupole current threshold to reach single-bunch stability in the LHC at flat top. Two bunches with dierent emittances are injected in the LHC in both B1 and B2 and the current in the Landau octupoles was progressively decreased until an instability developed. The measurements provide insight into the LHC impedance model by comparing them with the stabilizing octupole current predicted from DELPHI.

  7. 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...

  8. 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

  9. Impedance Analysis of Longitudinal Bunch Shape Measurements at PLS

    CERN Document Server

    Hwang, Ilmoon; Kim Eun San; Yoon, Moohyun

    2005-01-01

    We measured the longitudinal bunch shape by streak camera at 2.5 GeV Pohang Light Source. The impedances estimated by a series R+L model indicate a resistance R= 960 ohm, an inductance L= 80 nH and a longitudinal impedance Z/n= 0.53 ohm. The scaling law for the bunch lengthenig is expressed as I0

  10. The LHC Transverse Coupled-Bunch Instability

    CERN Document Server

    Mounet, Nicolas; Métral, Elias

    In this thesis, the problem of the transverse coupled-bunch instabilities created by the Large Hadron Collider (LHC) beam-coupling impedance, that can possibly limit the machine operation, is addressed thanks to several new theories and tools. A rather complete vision of the problem is proposed here, going from the calculation of the impedances and wake functions of individual machine elements, to the beam dynamics study. Firstly, new results are obtained in the theory of the beam-coupling impedance for an axisymmetric two-dimensional structure, generalizing Zotter's theories, and a new general theory is derived for the impedance of an infinite flat two-dimensional structure. Then, a new approach has been found to compute the wake functions from such analytically obtained beam-coupling impedances, over-coming limitations that could be met with standard discrete Fourier transform procedures. Those results are then used to obtain an impedance and wake function model of the LHC, based on the (resistive-) wall im...

  11. 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.

  12. An improved injector bunching geometry for ATLAS

    CERN Document Server

    Pardo, Richard C; Clifft, B E; Sherementov, S; Strickhorn, P

    2002-01-01

    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 PH 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 suppor...

  13. 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.

  14. A Novel Diagnostics of Ultrashort Electron Bunches Based on Detection of Coherent Radiation from Bunched Electron Beam in an Undulator

    CERN Document Server

    Saldin, Evgeny L; Yurkov, Mikhail V

    2004-01-01

    We propose a new method for measurements of the longitudinal profile of 100 femtosecond electron bunches for X-ray Free Electron Lasers (XFELs). The method is based on detection of coherent undulator radiation produced by modulated electron beam. Seed optical quantum laser is used to produce exact optical replica of ultrashort electron bunches. The replica is generated in apparatus which consists of an input undulator (energy modulator), and output undulator (radiator) separated by a dispersion section. The radiation in the output undulator is excited by the electron bunch modulated at the optical wavelength and rapidly reaches a hundred-MW-level power. We then use the now-standard method of ultrashort laser pulse-shape measurement, a tandem combination of autocorrelator and spectrum (FROG -- frequency resolved optical gating) providing real-time single-shot measurements of the electron bunch structure. The big advantage of proposed technique is that it can be used to determine the slice energy spread and emi...

  15. 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...

  16. 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.

  17. 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.

  18. Measuring the Bunch Frequency Multiplication at CTF3

    CERN Document Server

    Bettoni, S; Corsini, R; Dabrowski, A; Doebert, S; Egger, D; Ferrari, A; Lefevre, T; Rabiller, A; Skowronski, PK; Soby, L; Tecker, F; Welsch, CP

    2010-01-01

    The CLIC Test Facility 3 (CTF3) is being built and commissioned by an international collaboration to test the feasibility of the proposed Compact Linear Collider (CLIC) drive beam generation scheme. Central to this scheme is the use of RF deflectors to inject bunches into a delay loop and a combiner ring, in order to transform the initial bunch frequency of 1.5 GHz from the LINAC to a final bunch frequency of 12 GHz. The optimization procedure relies on several steps. The active length of each ring is carefully adjusted to within less than millimetre accuracy using a wiggler magnet. The transverse optics of the machine must be set up in a way to ensure beam isochronicity. Diagnostics based on optical Streak camera and RF power measurements have been designed to measure the longitudinal behaviour of the beam during the combination. This paper presents their performance and recent measurements

  19. Longitudinal Coupled-Bunch Instabilities in the CERN PS

    CERN Document Server

    Damerau, H; Mehler, M; Rossi, C; Shaposhnikova, E; Tückmantel, Joachim; Vallet, J L

    2007-01-01

    Longitudinal coupled bunch instabilities in the CERN PS represent a major limitation to the high brightness beam delivered for the LHC. To identify possible impedance sources for these instabilities, machine development studies have been carried out. The growth rates of coupled bunch modes have been measured, and modes have been identified using mountain range data. Growth rate estimations from coupled bunch mode theory are compared to these results. It is shown that the longitudinal impedance of the broad resonance curve of the main 10 MHz RF system can be identified as the most probable source. Several modes are driven simultaneously due to the large width of the resonance, which is considered for the analysis.

  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. 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.)

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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%

  7. Tax Bunching, Income Shifting and Self-employment

    DEFF Research Database (Denmark)

    le Maire, Christian Daniel; Schjerning, Bertel

    2013-01-01

    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...

  8. Tax Bunching, Income Shifting and Self-employment

    DEFF Research Database (Denmark)

    le Maire, Christian Daniel; Schjerning, Bertel

    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...

  9. 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)

  10. 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

  11. 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.

  12. 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...

  13. 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.

  14. Radiation sources and diagnostics with ultrashort electron bunches

    Energy Technology Data Exchange (ETDEWEB)

    Catravas, P.; Esarey, E.; Leemans, W.P.

    2001-11-02

    The basic principles and design of radiation sources (transition radiation, Cerenkov radiation, radiation from periodic structures, etc.) and radiation-based diagnostics will be discussed, with emphasis on radiation from ultra-short electron bunches. Ultra-short electron bunches have the potential to produce high peak flux radiation sources that cover wavelength regimes where sources are currently not widely available (coherent THz/IR) as well as ultrashort X-ray pulses (3-100 fs). While radiation from the electron bunch contains the full signature of the electron beam and/or medium it has travelled through, the deconvolution of a single property of interest can be difficult due to a large number of contributing properties. The experimental implementation of novel solutions to this problem will be described for beams from 30 MeV to 30 GeV, including fluctuational interferometry, source imaging, phase matched cone angles and laser-based techniques, which utilize optical transition radiation, wiggler and Cerenkov radiation, and Thomson scattering. These novel diagnostic methods have the potential to resolve fs bunch durations, slice emittance on fs scales, etc. The advantages and novel features of these techniques will be discussed.

  15. Modeling Multi-Bunch X-band Photoinjector Challenges

    Energy Technology Data Exchange (ETDEWEB)

    Marsh, R A; Anderson, S G; Gibson, D J; Barty, C J

    2012-05-09

    An X-band test station is being developed at LLNL to investigate accelerator optimization for future upgrades to mono-energetic gamma-ray technology at LLNL. The test station will consist of a 5.5 cell X-band rf photoinjector, single accelerator section, and beam diagnostics. Of critical import to the functioning of the LLNL X-band system with multiple electron bunches is the performance of the photoinjector. In depth modeling of the Mark 1 LLNL/SLAC X-band rf photoinjector performance will be presented addressing important challenges that must be addressed in order to fabricate a multi-bunch Mark 2 photoinjector. Emittance performance is evaluated under different nominal electron bunch parameters using electrostatic codes such as PARMELA. Wake potential is analyzed using electromagnetic time domain simulations using the ACE3P code T3P. Plans for multi-bunch experiments and implementation of photoinjector advances for the Mark 2 design will also be discussed.

  16. Simulations of Merging Helion Bunches on the AGS Injection Porch

    Energy Technology Data Exchange (ETDEWEB)

    Gardner, C. J. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-08-29

    During the setup of helions for the FY2014 RHIC run it was discovered that the standard scheme for merging bunches on the AGS injection porch required an injection kicker pulse shorter than what was available. To overcome this difficulty, K. Zeno proposed and developed an interesting and unusual alternative which uses RF harmonic numbers 12, 4, 2 (rather than the standard 8, 4, 2) to merge 8 helion bunches into 2. In this note we carry out simulations that illustrate how the alternative scheme works and how it compares with the standard scheme. This is done in Sections 13 and 14. A scheme in which 6 bunches are merged into 1 is simulated in Section 15. This may be useful if more helions per merged bunch are needed in future runs. General formulae for the simulations are given in Sections 9 through 12. For completeness, Sections 1 through 8 give a derivation of the turn-by-turn equations of longitudinal motion at constant magnetic field. The derivation is based on the work of MacLachlan. The reader may wish to skip over these Sections and start with Section 9.

  17. Simulation of single-bunch instabilities with HEADTAIL

    CERN Document Server

    Astapovych, Daria; Mounet, Nicolas Frank; CERN. Geneva. ATS Department

    2015-01-01

    Transverse collective instabilities are one of the most important limitations to achieve the highest luminosities in the LHC and have been regularly observed during the LHC Run I. We present here an analysis of single bunch instabilities observed in 2012, together with a comparison with HEADTAIL simulations using the LHC impedance model.

  18. 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.

  19. 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.

  20. 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).

  1. Bunch transverse emittance increase in electron storage rings

    Institute of Scientific and Technical Information of China (English)

    GAO Jie

    2009-01-01

    In this paper a theoretical framework to estimate the bunch transverse emittance growing in electron storage rings due to short range transverse wakefield of the machine is established. New equilibrium emittance equations are derived and applied to explain the experimentally obtained results in ATF damping ring. This equation will be useful for linear collider damping ring design.

  2. Single Bunch Stability in LER of PEP II

    Energy Technology Data Exchange (ETDEWEB)

    Heifets, S.; /SLAC; Sabbi, G.; /Fermilab

    2011-10-11

    The note describes results of studies of the single bunch stability in the low energy ring (LER) of the PEP-II B-factory. Simulations describe the potential well distortion (PWD) obtained by numerical solution of the Haiisinski equation and results on the beam stability obtained with the code TRISIM. Both longitudinal and transverse wake fields are taken into account. Preliminary estimates indicate that single bunch in the LER of the PEP-II B-factory has to be stable, both longitudinally and transversely, at the maximum design bunch current 1.8 mA (beam current 3A). However, realistic wakes of the machine has been constructed only recently using results of the extensive numerical simulations of the vacuum components of the ring. Additional to that, the code TRISIM, a simulation program for single-bunch collective effects written by one of the authors (G. S.), became recently available. This allows us to study beam stability in a more reliable way than it is possible analytically.

  3. 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.

  4. 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.

  5. 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.)

  6. 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.

  7. 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...

  8. 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)

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

    Institute of Scientific and Technical Information of China (English)

    XIANG Dao; YANG Xing-Fan; HUANG Wen-Hui; TANG Chuan-Xiang; LIN Yu-Zheng; LI Wei-Hua; PAN Qing; LI Ming

    2008-01-01

    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 0.73ps, which confirms a successful commissioning of the bunch compressor and the interferometer.

  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. 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)

  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. 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.

  15. 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

  16. 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.

  17. 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.

  18. Transient resistive wall wake for very short bunches

    CERN Document Server

    Stupakov, Gennady

    2005-01-01

    Work supported by U.S. Department of Energy, contract DE-AC03-76SF00515. The catch up distance for the resistive wall wake in a round pipe is approximately equal to the square of the pipe radius divided by the bunch length. The standard formulae for this wake are applicable at distances much larger than the catch up distance. For extremely short bunches, considered recently by Zholents and Fawley in application for SASE (PRL, vol. 92, p. 224801), this formation length can be tens of meters. In this paper, we calculate the resistive wall wake for such a beam at distances compared with the catch up distance assuming a constant wall conductivity. We also discuss how the derivation can be modified to include the frequency dependence of the conductivity characteristic for very short wavelength.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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)

  4. Characterizing the Temporal Structure of a Relativistic Electron Bunch

    Institute of Scientific and Technical Information of China (English)

    邓海啸; 冯超; 刘波; 王东; 王兴涛; 张猛

    2011-01-01

    Using proper beam energy chirp and the undulator detuning effect, we propose a modified optical replica synthesizer scheme to characterize the temporal structure of a relativistic electron bunch, which predicts a 100-fs temporal resolution in numerical simulation. The proof of principle experiment demonstrates a peak current of 9 A and a slice energy spread of about 0.5keV for the uncompressed electron beam of the Shanghai Deep UV Free Electron Laser Facility.%Using proper beam energy chirp and the undulator detuning effect,we propose a modified optical replica synthesizer scheme to characterize the temporal structure of a relativistic electron bunch,which predicts a 100-fs temporal resolution in numerical simulation.The proof of principle experiment demonstrates a peak current of 9 A and a slice energy spread of about 0.5 keV for the uncompressed electron beam of the Shanghai Deep UV Free Electron Laser Facility.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-05-01

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

  10. 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)

  11. 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

  12. 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)

  13. 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...

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. Simulation of Transverse Multi-Bunch Instabilities of Proton Beams in LHC

    CERN Document Server

    Koschik, Alexander; Zotter, Bruno

    The CERN Large Hadron Collider (LHC) is designed for highest luminosity and therefore requires operation with a large number of bunches and high intensities. Its performance could be limited by the electromagnetic interaction between the charged particle beam and its surroundings which cause collective instabilities. This thesis describes methods of simulating and analyzing multi-bunch instabilities in circular accelerators and storage rings. The simulation models as well as analyzing tools presented here, also facilitate the interpretation of measurements in multi-bunch machines. The 3-dimensional, multi-bunch tracking program MultiTRISIM was developed, based on its single-bunch predecessor TRISIM3D. It allows the exploration of longrange effects in round or flat vacuum chambers for equidistant or uneven filling schemes. Previous computer simulations of collective effects concentrated mainly on instabilities of single or few bunches in electron storage rings. There, the strong radiation damping reduces the r...

  1. 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.

  2. Strong-Strong Beam-Beam Simulation of Bunch Length Splitting at the LHC

    CERN Document Server

    Qiang, J; Pieloni, Tatiana; Ohmi, Kazuhito

    2015-01-01

    Longitudinal bunch length splitting was observed for some LHC beams. In this paper, we will report on the study of the observation using strong-strong beam-beam simulations. We explore a variety of factors including initial momentum deviation, collision crossing angle, synchrotron tune, chromaticity, working points and bunch intensity that contribute to the beam particle loss and the bunch length splitting, and try to understand the underlying mechanism of the observed phenomena.

  3. Spatial configuration of a plasma bunch formed under gyromagnetic resonance in a magnetic mirror trap

    Science.gov (United States)

    Andreev, V. V.; Novitskii, A. A.; Umnov, A. M.; Chuprov, D. V.

    2016-06-01

    The spatial configuration of a relativistic plasma bunch generated under the gyromagnetic autoresonance and confined in a magnetic mirror trap has been studied experimentally and numerically. The characteristics of bremsstrahlung generated by the plasma bunch from the gas and chamber walls were investigated using X-ray spectroscopy and radiometry, which made it possible to determine the localization of the bunch and analyze the dynamics of its confinement.

  4. 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.

  5. 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)

  6. 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

  7. 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)

  8. The source of THz radiation based on dielectric waveguide excited by sequence of electron bunches

    Science.gov (United States)

    Altmark, A. M.; Kanareykin, A. D.

    2016-07-01

    We present a new method for excitation of THz Cherenkov radiation in a dielectric waveguide by relativistic electron bunches. A sequence of bunches generates monochromatic radiation. The frequency of radiation is defined by the distance between the bunches. The studies were carried by using the newly updated BBU-3000 code which permits taking into account a number of additional options: an external quadrupole focusing system, group velocity of the wakefield, and the dielectric material loss factor. In this paper, we present our algorithm for optimizing the number and sequential positions of bunches for generation of narrow band high power THz radiation.

  9. 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

  10. 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

  11. 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.)

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

    Energy Technology Data Exchange (ETDEWEB)

    Bert, J.S.; Ruth, R.D.

    1995-08-01

    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.

  13. 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.

  14. Bunch-Crossing Identification for saturated calorimeter signals

    CERN Document Server

    Pfeiffer, Ullrich

    1999-01-01

    This paper describes an algorithm, which will be implemented in the Preprocessor ASIC of the ATLAS Level-1 Calorimeter trigger. Its purpose is to identify the corresponding Bunch-Crossing in time for saturated trigger tower signals from the calorimeters (saturated BCID). Results presented here are combined from simulations with a PSPICE model of the Liquid Argon trigger tower electronics and the digital signal processing inside the Preprocessor. The PSPICE model describes saturation of analogue pulses in a realistic way. The digital processing allows to investigate noise effects and shifts of the digitization strobe of the FADC against the pulse position.

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

    CERN Document Server

    Heifets, S

    2003-01-01

    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.

  16. 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...

  17. 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.

  18. 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

  19. 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

  20. 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

  1. 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.

  2. 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.

  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. 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.)

  5. 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 ...

  6. 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.}

  7. 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.

  8. Reducing energy spread for long bunch train at SLAC

    Energy Technology Data Exchange (ETDEWEB)

    Decker, F.-J.; Farkas, D. [Stanford Linear Accelerator Center, CA (United States); Rinolfi, L. [CERN, Geneva (Switzerland); Truher, J. [Stanford Linear Accelerator Center, CA (United States)

    1996-06-01

    The normal energy gain of the SLC RF system, using SLED (SLAC Energy Development) cavities, can accelerate only about 150 ns beam pulse within an energy spread of 0.5% with 10(exp 11) particles per pulse. By applying two additional 180 deg. phase inversions for about 20% of all SLC klystrons, the classical SLED pulse is flattened to achieve an energy spread of 0.3% over 240 ns which corresponds to 680 bunches in S-band. This scheme was developed for the fixed target experiment E-154, to study the neutron spin. It was used to run at a beam energy of 48.8 GeV and a beam charge of up to 10(exp 11) e- per pulse. This paper describes the beam loading compensation using early beam injection scheme and new RF phase inversions which have been implemented for the SLED devices. The experimental results, obtained during fall 1995, are compared to simulations. The results surpassed the initial requested beam qualities. A similar approach might be useful for future linear colliders with long bunch trains.

  9. A Drive Laser for Multi-Bunch Photoinjector Operation

    Energy Technology Data Exchange (ETDEWEB)

    Gibson, D J; Cormier, E; Messerly, M J; Prantil, M A; Barty, C J

    2012-05-11

    Numerous electron beam applications would benefit from increased average current without sacrificing beam brightness. Work is underway at LLNL to investigate the performance of X-band photoinjectors that would generate electron bunches at a rate matching the RF drive frequency, i.e. one bunch per RF cycle. A critical part of this effort involves development of photo-cathode drive laser technology. Here we present a new laser architecture that can generate pulse trains at repetition rates up to several GHz. This compact, fiber-based system is driven directly by the accelerator RF and so is inherently synchronized with the accelerating fields, and scales readily over a wide range of drive frequencies (L-band through X-band). The system will be required to produce 0.5 {mu}J, {approx}200 fs rise time, spatially and temporally shaped UV pulses designed to optimize the electron beam brightness. Presented is the current status of this system, producing 2 ps pulses from a continuous-wave source.

  10. 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.

  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. BIOCHEMICAL ESTIMATION OF PRIMARY METABOLITES OF CASSIA NODOSA BUNCH.

    Directory of Open Access Journals (Sweden)

    Ankita Yadav et al

    2012-09-01

    Full Text Available Cassia nodosa Bunch. is an ornamental tree belonging to family Leguminosae, popularly known as Pink Shower is a perennial tree. Laboratory evaluations were made to asses the study of primary metabolites in different plant parts of Cassia nodosa Bunch. The highest amount of soluble sugars (10.27mg/ gdw, lipids (32.36mg/gdw, phenols (20.0mg/gdw, DNA (11.78mg/gdw and Chlorophyll- a+b (0.94mg/gdw was observed in pods, ascorbic acid (0.867 mg/gdw, proteins (115.0mg/gdw, RNA (4.60mg/gdw and carotenoids (0.554mg/gdw in leaves and starch (10.02mg/gdw in stems. Similarly lowest amount of proteins (39.48mg/gdw, phenols (4.67mg /gdw, RNA (0.49mg/ gdw and DNA (1.76mg/gdw was observed in leaves, starch (3.76mg/gdw in flowers, soluble sugars (2.45mg/gdw, lipids (3.48mg /gdw, ascorbic acid (0.089mg/gdw in roots.

  13. Flat bunch creation and acceleration: a possible path for the LHC luminosity upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, C.M.; /Fermilab

    2009-05-01

    Increasing the collider luminosity by replacing bunches having Gaussian line-charge distribution with flat bunches, but with same beam-beam tune shift at collision, has been studied widely in recent years. But, creation of 'stable' flat bunches (and their acceleration) using a multiple harmonic RF system has not been fully explored. Here, we review our experience with long flat bunches in the barrier RF buckets at Fermilab.We presentsome preliminary results from beam dynamics simulations and recent beam studies in the LHC injectors to create stable flat bunches using double harmonic RF systems. The results deduced from these studies will be used to model the necessary scheme for luminosity upgrade in the LHC. We have also described a viable (and economical) way for creation and acceleration of flat bunches in the LHC. The flat bunch scheme may have many advantages over the LHC baseline scenario, particularly because of the reduced momentum spread of the bunch for increased intensities.

  14. 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

  15. 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.

  16. 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)

  17. 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

  18. Calculation of the Beam Field in the LCLS Bunch Length Monitor

    Energy Technology Data Exchange (ETDEWEB)

    Stupakov, G.; Ding, Y.; Huang, Z.; /SLAC

    2006-06-07

    Maintaining a stable bunch length and peak current is a critical step for the reliable operation of a SASE based x-ray source. In the LCLS, relative bunch length monitors (BLM) right after both bunch compressors are proposed based on the coherent radiation generated by the short electron bunch. Due to its diagnostic setup, the standard far field synchrotron radiation formula and well-developed numerical codes do not apply for the analysis of the BLM performance. In this paper, we develop a calculation procedure to take into account the near field effect, the effect of a short bending magnet, and the diffraction effect of the radiation transport optics. We find the frequency response of the BLM after the first LCLS bunch compressor and discuss its expected performance.

  19. 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)

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  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. 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

  6. 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.

  7. 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

  8. 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.

  9. Modeling Longitudinal Oscillations of Bunched Beams in Synchrotrons

    CERN Document Server

    Klingbeil, Harald; Mehler, Monika; Zipfel, Bernhard

    2010-01-01

    Longitudinal oscillations of bunched beams in synchrotrons have been analyzed by accelerator physicists for decades, and a closed theory is well-known [1]. The first modes of oscillation are the coherent dipole mode, quadrupole mode, and sextupole mode. Of course, these modes of oscillation are included in the general theory, but for developing RF control systems, it is useful to work with simplified models. Therefore, several specific models are analyzed in the paper at hand. They are useful for the design of closed-loop control systems in order to reach an optimum performance with respect to damping the different modes of oscillation. This is shown by the comparison of measurement and simulation results for a specific closed-loop control system.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

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

    International Nuclear Information System (INIS)

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

  15. 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.

  16. 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

  17. 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.

  18. 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.)

  19. 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.

  20. 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)

  1. 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...

  2. 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.

  3. 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.

  4. 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.

  5. 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)

  6. 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.

  7. Numerical calculation of the motion of dense electron bunch interacting with pulsed accelerating field in inhomogeneous cavity

    Energy Technology Data Exchange (ETDEWEB)

    Bakhvalov, N.S.; Zhidkov, E.P.; Kadantseva, E.P.; Rubin, S.B.; Serdyukova, S.I.

    1982-01-01

    Results of numerical calculation by the finite-differential method of self-consistent problem of the motion of dense electron bunch in inhomogeneous cavity is discussed. The pulsed strange wave with finite storage of energy, excited secondary and induced potential fields affects the bunch. Two problems are considered: in the first case bunch flies into the cavity, in the second one at the initial moment the bunch rests in the center of cavity. The energy balance in the dynamic system, bunch plus total electromagnetic field, is considered.

  8. 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)

  9. High intensity single bunch operation with heavy periodic transient beam loading in wide band rf cavities

    Science.gov (United States)

    Tamura, Fumihiko; Hotchi, Hideaki; Schnase, Alexander; Yoshii, Masahito; Yamamoto, Masanobu; Ohmori, Chihiro; Nomura, Masahiro; Toda, Makoto; Shimada, Taihei; Hasegawa, Katsushi; Hara, Keigo

    2015-09-01

    The rapid cycling synchrotron (RCS) in the Japan Proton Accelerator Research Complex (J-PARC) was originally designed to accelerate two high intensity bunches, while some of neutron experiments in the materials and life science experimental facility and a muon experiment using main ring beams require a single bunch operation mode, in which one of the two rf buckets is filled and the other is empty. The beam intensity in the single bunch operation has been limited by longitudinal beam losses due to the rf bucket distortions by the wake voltage of the odd harmonics (h =1 ,3 ,5 ) in the wide band magnetic alloy cavities. We installed an additional rf feedforward system to compensate the wake voltages of the odd harmonics (h =1 ,3 ,5 ). The additional system has a similar structure as the existing feedforward system for the even harmonics (h =2 ,4 ,6 ). We describe the function of the feedforward system for the odd harmonics, the commissioning methodology, and the commissioning results. The longitudinal beam losses during the single bunch acceleration disappeared with feedforward for the odd harmonics. We also confirmed that the beam quality in the single bunch acceleration are similar to that of the normal operation with two bunches. Thus, high intensity single bunch acceleration at the intensity of 2.3 ×1013 protons per bunch has been achieved in the J-PARC RCS. This article is a follow-up of our previous article, Phys. Rev. ST Accel. Beams 14, 051004 (2011). The feedforward system extension for single bunch operation was successful.

  10. 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.

  11. 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

  12. 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

  13. 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 ...

  14. 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.

  15. 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.

  16. 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.

  17. A Bunch Length Monitor for JLab 12 GeV Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Mahmoud Mohamad Ali [ODU; Freyberger, Arne P. [JLAB; Gubeli, Joseph F. [JLAB; Krafft, Geoffrey A. [JLAB

    2013-12-01

    A continuous non-invasive bunch length monitor for the 12 GeV upgrade of Jefferson Lab will be used to determine the bunch length of the beam. The measurement will be done at the fourth dipole of the injector chicane at 123 MeV using the coherent synchrotron light emitted from the dipole. The estimated bunch length is 333 fs. A vacuum chamber will be fabricated and a Radiabeam real time interferometer will be used. In this paper, background, the estimated calculations and the construction of the chamber will be discussed.

  18. 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.

  19. Design of a high-bunch-charge 112-MHz superconducting RF photoemission electron source

    Science.gov (United States)

    Xin, T.; Brutus, J. C.; 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.

    2016-09-01

    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. 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 to produce high-brightness and high-bunch-charge bunches for the coherent electron cooling proof-of-principle experiment. The gun utilizes a quarter-wave resonator geometry for assuring beam dynamics and uses high quantum efficiency multi-alkali photocathodes for generating electrons.

  20. Electron bunch structure in energy recovery linac with high-voltage dc photoelectron gun

    Science.gov (United States)

    Saveliev, Y. M.; Jackson, F.; Jones, J. K.; McKenzie, J. W.

    2016-09-01

    The internal structure of electron bunches generated in an injector line with a dc photoelectron gun is investigated. Experiments were conducted on the ALICE (accelerators and lasers in combined experiments) energy recovery linac at Daresbury Laboratory. At a relatively low dc gun voltage of 230 kV, the bunch normally consisted of two beamlets with different electron energies, as well as transverse and longitudinal characteristics. The beamlets are formed at the head and the tail of the bunch. At a higher gun voltage of 325 kV, the beam substructure is much less pronounced and could be observed only at nonoptimal injector settings. Experiments and computer simulations demonstrated that the bunch structure develops during the initial beam acceleration in the superconducting rf booster cavity and can be alleviated either by increasing the gun voltage to the highest possible level or by controlling the beam acceleration from the gun voltage in the first accelerating structure.

  1. 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.

  2. 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.

  3. 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.)

  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. 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.

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

    Directory of Open Access Journals (Sweden)

    Zhang Zhi

    2009-01-01

    Full Text Available Abstract 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.

  7. Longitudinal bunch profile diagnostics in the 50fs range using coherent Smith-Purcell radiation

    CERN Document Server

    Delerue, Nicolas; Maclean, Ewen; Reichold, Armin

    2009-01-01

    We have considered the possibility of using coherent Smith-Purcell radiation for the single-shot determination of the longitudinal profile of 50 fs (FWHM) long electron bunches. This length is typical for the bunches currently produced by Laser Wakefield Acceleration and is at the limit of what is achievable by alternative techniques, such as Electro-Optic sampling. It is concluded that there are no obstacles, either theoretical or experimental, in the implementation of this technique. A set of three gratings, with periods of 15, 85 and 500 micrometres, will produce detectable energy in the wavelength region 10-1000 micrometres, which should be adequate for the reconstruction of the bunch shape by the Kramers-Kronig technique. For bunch charges of 109 electrons, or more, the radiated energy can be detected by room temperature pyroelectric detectors. The limits of possible extension of the technique to even shorter lengths are also considered.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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...

  13. 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...

  14. 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.

  15. Bunch length measurement at the Fermilab A0 photoinjector using a Martin-Puplett interferometer

    Energy Technology Data Exchange (ETDEWEB)

    Thurman-Keup, Randy; Fliller, Raymond Patrick; Kazakevich, Grigory; /Fermilab

    2008-05-01

    We present preliminary measurements of the electron bunch lengths at the Fermilab A0 Photoinjector using a Martin-Puplett interferometer on loan from DESY. The photoinjector provides a relatively wide range of bunch lengths through laser pulse width adjustment and compression of the beam using a magnetic chicane. We present comparisons of data with simulations that account for diffraction distortions in the signal and discuss future plans for improving the measurement.

  16. 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.

  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. 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...

  19. 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...

  20. 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...

  1. Stochastic cooling of bunched beams from fluctuation and kinetic theory

    Energy Technology Data Exchange (ETDEWEB)

    Chattopadhyay, S.

    1982-09-01

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

  2. Bunching high intensity proton beams with a CH-DTL

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, Malte; Claessens, Christine; Heilmann, Manuel; Hinrichs, Ole; Koser, Daniel; Meusel, Oliver; Noll, Daniel; Podlech, Holger; Ratzinger, Ulrich; Seibel, Anja [Institut fuer Angewandte Physik, Goethe-Universitaet Frankfurt am Main (Germany)

    2014-07-01

    The Frankfurt Neutron Source at the Stern-Gerlach-Zentrum (FRANZ) will provide ultra short neutron pulses at high intensities and repetition rates. The facility is under construction with an expected first beam by the end of 2014. A 5-Gap CH rebuncher is installed behind a coupled RFQ/IH-DTL combination at the end of the LINAC section between two magnetic quadrupole triplets. It will be used for varying the final energy between 1.8 and 2.2 MeV, as well as for focusing the proton beam bunch longitudinally, to compensate RF defocusing effects and huge space charge forces at currents up to 200 mA at the final stage of extension. Therefore high current beam dynamic simulations are in progress. They include benchmarking of different beam dynamic codes like LORASR, TraceWin and Bender (a new PIC tracking code developed at IAP), as well as validating the results by measurements. Detailed error tolerance studies, thermal simulations and examination of multipole field impact, due to the cavity geometry, are also done. Furthermore, this CH rebuncher serves as prototype for CH cavity operation at MYRRHA (Belgium), an Accelerator Driven System (ADS) for transmutation of high level nuclear waste. After copper-plating the cavity, RF conditioning will start in spring 2014.

  3. 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.

  4. 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.

  5. Peculiarities of step bunching on Si(001) surface induced by DC heating

    Science.gov (United States)

    Latyshev, A. V.; Litvin, L. V.; Aseev, A. L.

    1998-06-01

    An evolution of the stepped Si(001) surface, induced by the electric current heating the crystal, has been observed directly by an in situ ultra-high vacuum reflection electron microscopy (UHV REM). Two scenarios of the initial stages of step bunching, depending on the average step-step distance, were detected: monatomic step coupling and polycentric nucleation of large terraces. From the successive REM images of step bunching, the step number in the bunch was accounted to depend on the annealing time as a power-law function with a scaling exponent equal to 0.53±0.05. Also, the average distance between coupled steps in the bunch was measured as a root-square dependence on the number of the coupled steps in this bunch. In spite of essential difference in the structural properties of Si(001) and Si(111) surfaces, the monatomic step behavior seems to be described by the same kinetic mechanism of step bunching induced by DC heating.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-08-01

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

  7. 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.

  8. 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

  9. 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.

  10. 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.

  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. Holographic Spectroscopy for Rapid Electron Bunch Analysis: Development of an Instrument with THZ Resolved Optical Gating

    Energy Technology Data Exchange (ETDEWEB)

    Sievers, Albert

    2011-10-28

    The main thrust of our project was to apply the concepts of holographic spectroscopy, developed earlier in the visible and near IR spectral regions for satellite mapping, to the THz region in order to measure the spectral signature of the coherent radiation emanating from a relativistic electron bunch to obtain the bunch length itself. There were four major discoveries. (1) In the course of this ground-breaking work we developed and built the first static THz interferometer suitable for the realization of such a holographic Fourier transform spectrometer. Experimental tests and analysis of the observed results have provided the necessary foundation for future development of THz detector arrays optimized for spectroscopic applications. (2) Since such detectors do not exist at the present time our next effort was to find an alternative approach. We explored the electro-optic (EO) detection of the THz pulse using the short pulse of a visible diode laser synchronized to the bunch with the long-term goal aimed at single bunch measurement capability. The main hurdle was found to be the parasitic scattering of the diode radiation in the EO medium. By using the optical Fourier transform of the THz interference pattern the effects of this background were suppressed enough to obtain the spectrum using multiple shot acquisition. During our experiments at the FLASH facility at DESY we determined that for single bunch measurement capability the diode laser has to be able to produce sub 100 ps pulses with peak power of at least 1 W. Since these parameters are quite feasible at the current stage of diode laser science this combination of techniques can be used for single shot measurement of a short electron bunch. (3) In carrying out the above effort a simpler measurement possibility was uncovered involving the visible/nearIR pulse of incoherent radiation produced by the same bunch. This observation made possible the cross-correlation of the THz coherent and visible incoherent

  13. Development of a Turn-by-Turn Beam Position Monitoring System for Multiple Bunch Operation of the ATF Damping Ring

    CERN Document Server

    Burrows, P N; Kraljevic, N Blaskovic; Christian, G B; Davis, M R; Perry, C; Apsimon, R J; Constance, B; Gerbershagen, A; Resta-Lopez, J

    2012-01-01

    An FPGA-based monitoring system has been developed to study multi-bunch beam instabilities in the damping ring (DR) of the KEK Accelerator Test Facility (ATF). The system utilises a stripline beam position monitor (BPM) and single-stage down-mixing BPM processor. The system is designed to record the horizontal and/or vertical positions of up to three bunches in the DR with c. 150ns bunch spacing, or the head bunch of up to three trains in a multi-bunch mode with a bunch spacing of 5.6 ns. The FPGA firmware and data acquisition software allow the recording of turnby-turn data. An overview of the system and performance results will be presented.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-24

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

  15. Infrared single shot diagnostics for the longitudinal profile of the electron bunches at FLASH

    International Nuclear Information System (INIS)

    The longitudinal profile of electron bunches plays an important role in the design of single-pass free electron lasers and future linear e+e- colliders. For the free electron laser FLASH in Hamburg, a longitudinal compression scheme is used which results in an asymmetric longitudinal bunch profile with a 'spike'. This 'spike', which has a very high peak current, is used in a high-gain SASE-FEL process to produce high intensity (about 70 μJ) femtosecond photon pulses in the XUV wavelength range. The required high peak current of the electron bunch is realized by confining a large number of electrons in a width, measured in time units, of few tens of femtosecond, making the diagnostics of such bunches a challenge. Furthermore, the operation of facilities such as FLASH shows that single-shot diagnostics is indispensable. It is intuitive to use a time domain method to measure the electron bunch length. However, when the structures present in the bunch profile fall in the femtoseconds range, this is beyond the resolution of time-resolved methods developed so far. In this thesis, a wavelength-domain technique is described that can fulfill both requirements of single shot and high resolution reaching to the femtoseconds range. The amount of charge that is confined in a typical length of several femtoseconds (FWHM of the spike) can be determined by a novel single-shot spectrometer that resolves the coherent radiation (e.g. coherent transition radiation) in the far-infrared and mid-infrared range. Furthermore the extension of this single-shot spectroscopy to shorter wavelengths reaching the near-infrared, makes it possible to investigate the presence of structures in the bunch profile that might correlate or anti-correlate to the SASE intensity. (orig.)

  16. Infrared single shot diagnostics for the longitudinal profile of the electron bunches at FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Delsim-Hashemi, Hossein

    2008-09-15

    The longitudinal profile of electron bunches plays an important role in the design of single-pass free electron lasers and future linear e{sup +}e{sup -} colliders. For the free electron laser FLASH in Hamburg, a longitudinal compression scheme is used which results in an asymmetric longitudinal bunch profile with a 'spike'. This 'spike', which has a very high peak current, is used in a high-gain SASE-FEL process to produce high intensity (about 70 {mu}J) femtosecond photon pulses in the XUV wavelength range. The required high peak current of the electron bunch is realized by confining a large number of electrons in a width, measured in time units, of few tens of femtosecond, making the diagnostics of such bunches a challenge. Furthermore, the operation of facilities such as FLASH shows that single-shot diagnostics is indispensable. It is intuitive to use a time domain method to measure the electron bunch length. However, when the structures present in the bunch profile fall in the femtoseconds range, this is beyond the resolution of time-resolved methods developed so far. In this thesis, a wavelength-domain technique is described that can fulfill both requirements of single shot and high resolution reaching to the femtoseconds range. The amount of charge that is confined in a typical length of several femtoseconds (FWHM of the spike) can be determined by a novel single-shot spectrometer that resolves the coherent radiation (e.g. coherent transition radiation) in the far-infrared and mid-infrared range. Furthermore the extension of this single-shot spectroscopy to shorter wavelengths reaching the near-infrared, makes it possible to investigate the presence of structures in the bunch profile that might correlate or anti-correlate to the SASE intensity. (orig.)

  17. Spectral reflectance analysis of longkong (Lansium domesticum Corr. bunches as an indicator for optimal harvesting

    Directory of Open Access Journals (Sweden)

    Kaewtubtim, P.

    2007-09-01

    Full Text Available To determine the appropriate harvesting time of Longkong bunches, the spectral reflectance of ripening bunches was investigated from images taken by a digital camera using red LED and green LED. Every day images were taken from selected bunches at a Longkong estate during the growth of the bunches from immaturity to the over-ripe phase, to trace the changes in color that correlate with the process of ripening. The images were analyzed by measuring the changes in the three basic colors i.e. red, green and blue, using a specially developed Color Analysis computer program of Longkong "fruit" (CAOL, and then the obtained results were compared with the sweet in form of total soluble solid (TSS:TA.The result showed that the blue light reflectance from red LED source (Br was selected as an indicator for harvesting Longkong bunches. Br was inversely proportional to ripeness of Longkong. The blue color intensity decreases linearly while TSS:TA increases monotonously. From our investigations, we suggest that the time interval to harvest Longkong should be within 96 ±7 days after the first flower blossom of that bunch takes place while blue level per pixel was in the range of 8.67-2.39. If Longkong bunch was cut while the blue color level was in the range of 8.67-5.53, its taste will be sweet and sour and strong enough for long distance shipment. But if the blue level per pixel was in the range of 5.52-2.39, it has a very good taste and is suitable a for sale in the local area. In addition, it was also found that the blue level per pixel usually decreased at the rate of 0.45 per day. This made is possible to predict the harvesting day by this technique.

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

    International Nuclear Information System (INIS)

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

  19. Long-term genomic selection for heterosis without dominance in multiplicative traits: case study of bunch production in oil palm

    OpenAIRE

    Cros, David; Denis, Marie; Bouvet, Jean-Marc; Sánchez, Leopoldo

    2015-01-01

    Background To study the potential of genomic selection for heterosis resulting from multiplicative interactions between additive and antagonistic components, we focused on oil palm, where bunch production is the product of bunch weight and bunch number. We simulated two realistic breeding populations and compared current reciprocal recurrent selection (RRS) with reciprocal recurrent genomic selection (RRGS) over four generations. All breeding strategies aimed at selecting the best individuals...

  20. Long-term genomic selection for heterosis without dominance in multiplicative traits: case study of bunch production in oil palm

    OpenAIRE

    Cros, David; Denis, Marie; Bouvet, Jean-Marc; Sanchez, Leopoldo

    2015-01-01

    Background: To study the potential of genomic selection for heterosis resulting from multiplicative interactions between additive and antagonistic components, we focused on oil palm, where bunch production is the product of bunch weight and bunch number. We simulated two realistic breeding populations and compared current reciprocal recurrent selection (RRS) with reciprocal recurrent genomic selection (RRGS) over four generations. All breeding strategies aimed at selecting the best individual...

  1. Emittance growth and instability induced by space charge effect during final beam bunching in HIF accelerator system

    Science.gov (United States)

    Kikuchi, T.; Someya, T.; Kawata, S.; Nakajima, M.; Horioka, K.

    2006-06-01

    Beam dynamics and emittance growth are investigated by using particle-in-cell simulations during a final beam bunching for a driver system of inertial fusion driven by intense heavy ion beams. Space-charge-dominated beams are transported by a transverse confinement lattice with longitudinal compression, and the emittance increases along the longitudinal beam bunching. Dipole oscillations are excited due to the initial displacement of the beam center. The displacement causes the additional emittance growth during the final beam bunching.

  2. Summary of LHC MD 398: Verification of the dependence of the BCTF measurements on beam position and bunch length

    CERN Document Server

    Krupa, Michal; Gasior, Marek; Lefevre, Thibaut; Soby, Lars; CERN. Geneva. ATS Department

    2015-01-01

    The main aim of the MD was to study the dependency of bunch-by-bunch intensity measurements to beam position and bunch length variations. Large beam position offsets in IR4 and varying bunch length were introduced to compare the performance of the presently installed Fast Beam Current Transformers with the new Integrating Current Transformer and the new Wall Current Transformer. This note explains all the procedures of the LHC MD 398, which took place on 20/07/2015, and presents the obtained results.

  3. Q-switched-like soliton bunches and noise-like pulses generation in a partially mode-locked fiber laser.

    Science.gov (United States)

    Wang, Zhenhong; Wang, Zhi; Liu, Yan-Ge; Zhao, Wenjing; Zhang, Hao; Wang, Shangcheng; Yang, Guang; He, Ruijing

    2016-06-27

    We report an intermediate regime between c.w. emission and noise-like pulses (NLPs) regime in an Er-doped partially mode-locked fiber laser with nonlinear polarization rotation. In this regime, the soliton bunches stochastically turn up from a quasi-cw background in the Q-switched-like envelope. The soliton bunches normally last for tens or hundreds of intracavity round-trips. When the soliton bunches vanish, typical NLPs chains are generated sporadically at location where the soliton bunches collapses. These results would be helpful to understand the generation and property of the NLPs regime. PMID:27410624

  4. Different charges in the same bunch train at the European XFEL

    Energy Technology Data Exchange (ETDEWEB)

    Kot, Yauhen; Limberg, Torsten; Zagorodnov, Igor

    2013-11-15

    The injector of the European XFEL was initially designed for the operation with 1nC bunch charges. Later the flexibility of the nominal design of the injector with respect to the bunch charge was studied and extended also for smaller bunch charges down to 20 pC. A very tempting upgrade of this extension would be the operation of the European XFEL with different charges in the same train. It would make it suitable also for the experiments which require simultaneously different SASE pulse length or radiation power. Operation of two bunches within the same train sets new requirements on the working points of the injector which are to be satisfied additionally to the ones of a single charge operation. From the beam dynamics point of view here is to mention the similarity of the beam optical functions after the first accelerating module and suitable for lasing shapes of both bunches in the train at the end of the linac. Due to different charges and thus to different space charge forces which act on bunches during the passage of the linac the last condition cannot be easily satisfied even if the similarity of optical functions at the beginning of the linac is achieved. A more subtle analysis of the interplay between mismatch of beam optical functions, emittance growth in the injector and different 6D beam dynamics in the linac is needed with the final goal of successful lasing of both charges. In this paper we have investigated the possibility of the operation of different charges in the bunch train for the nominal design of the injector and for the case that it is extended by an additional laser system on the cathode. We have examined the problem of similarity of beam optical functions for different bunches in a train. We report also about the sensitivity of the beam optical functions on the chosen compression scenario and give an overview over the working points for the settings at the injector for single charge operation as well as combined working points for

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

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

    Saldin, E L; Yurkov, M V

    2004-01-01

    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, a tandem combination of autocorrelator and spectrum (FROG -- frequency resolved optical gating). The FROG trace of the optical replica of electron bunch gives accurate and rapid electron bunch shape measurements in a way similar to a f...

  7. Infrared Spectroscope for Electron Bunch-length Measurement: Heat Sensor Parameters Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Domgmo-Momo, Gilles; /Towson U. /SLAC

    2012-09-05

    The Linac Coherent Light Source (LCLS) is used for many experiments. Taking advantage of the free electron laser (FEL) process, scientists of various fields perform experiments of all kind. Some for example study protein folding; other experiments are more interested in the way electrons interact with the molecules before they are destroyed. These experiments among many others have very little information about the electrons x-ray produced by the FEL, except that the FEL is using bunches less than 10 femtoseconds long. To be able to interpret the data collected from those experiments, more accurate information is needed about the electron's bunch-length. Existing bunch length measurement techniques are not suitable for the measurement of such small time scales. Hence the need to design a device that will provide more precise information about the electron bunch length. This paper investigates the use of a pyreoelectric heat sensor that has a sensitivity of about 1.34 micro amps per watt for the single cell detector. Such sensitivity, added to the fact that the detector is an array sensor, makes the detector studied the primary candidate to be integrated to an infrared spectrometer designed to better measure the LCLS electron bunch length.

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

    Science.gov (United States)

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

    2014-07-01

    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 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. PMID:24971980

  9. Fast digital transverse feedback system for bunch train operation in CESR

    International Nuclear Information System (INIS)

    We have developed a time domain transverse feedback system with the high bandwidth needed to control transverse instabilities when the CESR e+e-collider is filled with trains of closely spaced bunches. This system is based on parallel digital processors and a stripline driver. It is capable of acting on arbitrary patterns of bunches having a minimum spacing of 14 ns. Several simplifying features have been introduced. A single shorted stripline kicker driven by one power amplifier is used to control both counter-rotating beams. The desired feedback phase is achieved by sampling the bunch position at a single location on two independently selectable beam revolutions. The system adapts to changes in the betatron tune, bunch pattern, or desired damping rate through the loading of new parameters into the digital processors via the CESR control system. The feedback system also functions as a fast gated bunch current monitor. Both vertical and horizontal loops are now used in CESR operation. The measured betatron damping rates with the transverse feedback system in operation are in agreement with the analytical prediction and a computer simulation developed in connection with this work. (author)

  10. Fast digital transverse feedback system for bunch train operation in CESR

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, J.T.; Billing, M.G.; Dobbins, J.A. [Cornell Univ., Ithaca, NY (United States). Lab. of Nuclear Studies] [and others

    1996-08-01

    We have developed a time domain transverse feedback system with the high bandwidth needed to control transverse instabilities when the CESR e{sup +}e{sup -} collider is filled with trains of closely spaced bunches. This system is based on parallel digital processors and a stripline driver. It is capable of acting on arbitrary patterns of bunches having a minimum spacing of 14 ns. Several simplifying features have been introduced. A single shorted stripline kicker driven by one power amplifier is used to control both counter-rotating beams. The desired feedback phase is achieved by sampling the bunch position at a single location on two independently selectable beam revolutions. The system adapts to changes in the betatron tune, bunch pattern, or desired damping rate through the loading of new parameters into the digital processors via the CESR control system. The feedback system also functions as a fast gated bunch current monitor. Both vertical and horizontal loops are now used in CESR operation. The measured betatron damping rates with the transverse feedback system in operation are in agreement with the analytical prediction and a computer simulation developed in connection with this work. (author)

  11. Use of ramped bunches for an enhancing of transformer ratio in coaxial dielectric structures

    International Nuclear Information System (INIS)

    A main parameter of the dielectric wakefield accelerator is the transformation ratio. To in-crease it was suggested to use ramped bunch trains (so-called the RBT-technics) or multizone dielectric structures (CDWA). We demonstrate the possibility of use of RBT-technics to increase the transformer ratio in two channel dielectric structures. Two channel dielectric structure is two concentric dielectric tubes, mounted in metal casing. Axial vacuum channel is the acceleration channel for witness bunch, and the second vacuum channel is the transport channel for drive bunches. We show that for a significant increase in the transformer ratio in coaxial dielectric structures the conventional RBT technics should be modified. We report a modified algorithm of the charge distribution between bunches of train and spacing between them. Improved algorithm for the RBT-technics has been demonstrated for 30 GHz CDWA and 0.44 THz CDWA. In the first case it is possible to increase the transformer ratio from 3.8 to 20, while in the second case it was possible to increase the transformer ratio from 5.5 to 17. Also we study the transverse stability of the ramped drive bunch train in coaxial dielectric structures and compare this stability with single-channel dielectric structures.

  12. Six-dimensional measurements of trains of high brightness electron bunches

    Science.gov (United States)

    Cianchi, A.; Alesini, D.; Anania, M. P.; Bacci, A.; Bellaveglia, M.; Castellano, M.; Chiadroni, E.; Di Giovenale, D.; Di Pirro, G. P.; Ferrario, M.; Gallo, A.; Innocenti, L.; Mostacci, A.; Pompili, R.; Rossi, A. R.; Scifo, J.; Shpakov, V.; Vaccarezza, C.; Villa, F.

    2015-08-01

    Trains of ultrashort electron pulses with THz repetition rate, so-called comblike beams, are assuming an ever growing interest in plasma-based acceleration. In particle-driven plasma wakefield acceleration (PWFA), a train of driver bunches with separation of the order of plasma wavelength, i.e., 300 μ m , resonantly excites a plasma wake, which accelerates a trailing witness bunch, injected at the accelerating phase. Comblike beams have great potentialities in different fields of applications. In particular, radiation sources, such as free-electron lasers and THz radiation, take advantage from the possibility to tailor electron beams modulated both in time and energy, to customize emission bandwidth and temporal properties. In these scenarios, the manipulation of longitudinal phase space to investigate different bunch configurations, in terms of energy and time separation, is founded on the knowledge of the 6D phase space of each bunch in the train. In this paper we present the methods developed at the SPARC_LAB test facility in order to fulfill the requirements. Starting from conventional diagnostics, therefore applying well-known tools using more than one diagnostic at the same time, we have completely characterized not only the full 6D phase space of a comblike electron beam with THz repetition rate, but also each single bunch within the train. To our knowledge, this is the first time such a measurement has been performed. Experimental results for multibunch trains in different configurations, suitable for PWFA applications, will be shown and discussed.

  13. A 4 GS/sec Instability Feedback Processing System for Intra-bunch Instabilities

    CERN Document Server

    Dusatko, J; Fox, J D; Pollock, K; Rivetta, C H; Turgut, O; Hofle, W

    2013-01-01

    We present the architecture and implementation overview of a proof-of-principle digital signal processing system developed to study control of Electron-Cloud and Transverse Mode Coupling Instabilities (TMCI) in the CERN SPS. This system is motivated by intensity increases planned as part of the High Luminosity LHC upgrade. It is based on a reconfigurable processing architecture which samples intra-bunch motion and applies correction signals at a 4GSa/s rate, allowing multiple samples across a single 3.2ns SPS bunch. This initial demonstration system is a rapidly developed prototype consisting of both commercial and custom- designed hardware that implements feedback control on a single bunch. It contains a high speed ADC and DAC, capable of sampling at up to 4GSa/s, with a 16-tap FIR control filter for each bunch sample slice. Other system features include a timing subsystem to synchronize the sampling to the injection and the bunch 1 markers, the capability of generating arbitrary time domain signals to drive...

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

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-07-01

    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 ({zeta} = {delta}Q/({delta}p/p)) for example, enabled to raise the charge per bunch, but to the detriment of beam lifetime. In addition, since the impedance of the vacuum chamber deteriorates with the installation of new insertion devices, the current thresholds tend to dope down continuously. The goal of this Working Group was then to review these limitations in the existing storage rings, where a large number of beam measurements have been performed to characterise them, and to discuss different strategies which are used against them. About 15 different laboratories reported on the present performance of storage rings, experiences gained in high charge per bunch, and on simulation results and theoretical studies. More than 25 presentations addressed the critical issues and stimulated the discussion. Four main topics came out: - Observation and experimental data; - Impedance studies and tracking codes; - Theoretical investigations; - Cures and feedback. (author)

  15. Radiation from laser accelerated electron bunches: Coherent terahertz and femtosecond X-rays

    International Nuclear Information System (INIS)

    Electron beam based radiation sources provide electromagnetic radiation for countless applications. The properties of the radiation are primarily determined by the properties of the electron beam. Compact laser driven accelerators are being developed that can provide ultra-short electron bunches (femtosecond duration) with relativistic energies reaching towards a GeV. The electron bunches are produced when an intense laser interacts with a dense plasma and excites a large amplitude plasma density modulation (wakefield) that can trap background electrons and accelerate them to high energies. The short pulse nature of the accelerated bunches and high particle energy offer the possibility of generating radiation from one compact source that ranges from coherent terahertz to gamma rays. The intrinsic synchronization to a laser pulse and unique character of the radiation offers a wide range of possibilities for scientific applications. Two particular radiation source regimes are discussed: Coherent terahertz emission and x-ray emission based on betatron oscillations and Thomson scattering

  16. Temporal characterization of ultrashort ionization-injected electron bunches generated from a laser wakefield accelerator

    CERN Document Server

    Zhang, C J; 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

    2016-01-01

    A new concept to diagnose the temporal characteristics of ultrashort electron bunches 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 separated by half a laser wavelength. By analyzing the modulated energy spectrum, the beam current profile and the longitudinal (energy versus time) phase space are recovered. This concept is demonstrated through particle-in-cell simulations and experiment.

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

    Science.gov (United States)

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

    1996-01-01

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

  18. Halo formation in three-dimensional bunches with various phase space distributions

    Science.gov (United States)

    Fedotov, A. V.; Gluckstern, R. L.; Kurennoy, S. S.; Ryne, R. D.

    1999-01-01

    A realistic treatment of halo formation must take into account 3D beam bunches and 6D phase space distributions. We recently constructed, analytically and numerically, a new class of self-consistent 6D phase space stationary distributions, which allowed us to study the halo development mechanism without being obscured by the effect of beam redistribution. In this paper we consider nonstationary distributions and study how the halo characteristics compare with those obtained using the stationary distribution. We then discuss the effect of redistribution on the halo development mechanism. In contrast to bunches with a large aspect ratio, we find that the effect of coupling between the r and z planes is especially important as the bunch shape becomes more spherical.

  19. Bunching properties of a classical microtron-injector for a far infrared free electron laser

    CERN Document Server

    Kazakevitch, Grigori M; Vinokurov, N A; Jeong Young Uk; Lee Byung Cheol; Lee, J

    2001-01-01

    Longitudinal bunching properties of a classical microtron have been investigated by the numerical simulation of the longitudinal motion of accelerated electrons. The simulations were performed for the 12-turn microtron that has been used as an injector for the KAERI far infrared free electron laser. Based on the bunching properties of the electron beam, the temporal distribution of the coherent undulator radiation power during a macro pulse from the free electron laser was calculated. In the calculations, we took into account the dispersion properties of the accelerating cavity and deviations of the bunch repetition rate that were measured by the heterodyne method in real operating conditions of the microtron. The calculation results are compared with the experimental data.

  20. Bunching properties of a classical microtron-injector for a far infrared free electron laser

    Science.gov (United States)

    Kazakevitch, Grigori M.; Serednyakov, Stanislav S.; Vinokurov, Nikolai A.; Jeong, Young Uk; Lee, Byung Cheol; Lee, Jongmin

    2001-12-01

    Longitudinal bunching properties of a classical microtron have been investigated by the numerical simulation of the longitudinal motion of accelerated electrons. The simulations were performed for the 12-turn microtron that has been used as an injector for the KAERI far infrared free electron laser. Based on the bunching properties of the electron beam, the temporal distribution of the coherent undulator radiation power during a macro pulse from the free electron laser was calculated. In the calculations, we took into account the dispersion properties of the accelerating cavity and deviations of the bunch repetition rate that were measured by the heterodyne method in real operating conditions of the microtron. The calculation results are compared with the experimental data.

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

    CERN Document Server

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

    2012-01-01

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

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

    Science.gov (United States)

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

    2014-12-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Winter, A.

    2004-07-01

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

  4. Radiation from laser accelerated electron bunches: Coherent terahertz and femtosecond X-rays

    Energy Technology Data Exchange (ETDEWEB)

    Leemans, W.P.; Esarey, E.; van Tilborg, J.; Michel, P.A.; Schroeder, C.B.; Toth, Cs.; Geddes, C.G.R.; Shadwick, B.A.

    2004-10-01

    Electron beam based radiation sources provide electromagnetic radiation for countless applications. The properties of the radiation are primarily determined by the properties of the electron beam. Compact laser driven accelerators are being developed that can provide ultra-short electron bunches (femtosecond duration) with relativistic energies reaching towards a GeV. The electron bunches are produced when an intense laser interacts with a dense plasma and excites a large amplitude plasma density modulation (wakefield) that can trap background electrons and accelerate them to high energies. The short pulse nature of the accelerated bunches and high particle energy offer the possibility of generating radiation from one compact source that ranges from coherent terahertz to gamma rays. The intrinsic synchronization to a laser pulse and unique character of the radiation offers a wide range of possibilities for scientific applications. Two particular radiation source regimes are discussed: Coherent terahertz emission and x-ray emission based on betatron oscillations and Thomson scattering.

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

    International Nuclear Information System (INIS)

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

  6. Extraction of High Charge Electron Bunch from the ELSA RF Injector Comparison Between Simulation and Experiment

    CERN Document Server

    Lemaire, J; Binet, A; Lagniel, J M; Le Flanchec, V; Pichoff, N

    2004-01-01

    A new scheme based on a photoinjector and a RF linear accelerator operating at 352 MHz has been recently proposed as a versatile radiographic facility. Beam pulses of 60 ns duration contain 20 succesive electron bunches which will be extracted at 2.5 MeV from a photoinjector then accelerated through the next structure to the final energy of 51 MeV. Bunches carrying 100 nC are required for this purpose. As a first demonstrating step, 50 nC electron bunches have been produced and accelerated to 2.5 MeV with the 144 MHz ELSA photoinjector at Bruyères le Chatel. For this experiment, we compare the results and the numerical simulations made with PARMELA, MAGIC and MAFIA codes.

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

    Science.gov (United States)

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

    1993-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Douglas, David R; Tennant, Christopher

    2015-11-10

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

  9. Direct observation of spatio-temporal dynamics of short electron bunches in storage rings

    CERN Document Server

    Evain, C; Parquier, M Le; Szwaj, C; Tordeux, M -A; Manceron, L; Brubach, J -B; Roy, P; Bielawski, S

    2016-01-01

    In recent synchrotron radiation facilities, the use of short (picosecond) electron bunches is a powerful method for producing giant pulses of Terahertz Coherent Synchrotron Radiation (THz CSR). Here we report on the first direct observation of these pulse shapes with a few picoseconds resolution, and of their dynamics over a long time. We thus confirm in a very direct way the theories predicting an interplay between two physical processes. Below a critical bunch charge, we observe a train of identical THz pulses (a broadband Terahertz comb) stemming from the shortness of the electron bunches. Above this threshold, a large part of the emission is dominated by drifting structures, which appear through spontaneous self-organization. These challenging single-shot THz recordings are made possible by using a recently developed photonic time stretch detector with a high sensitivity. The experiment has been realized at the SOLEIL storage ring.

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

    Science.gov (United States)

    Douglas, David R; Tennant, Christopher

    2015-11-10

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

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

    CERN Document Server

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

    2000-01-01

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

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

    CERN Document Server

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

    2016-01-01

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

  13. Halo Formation in 3-D Bunches with Self-Consistent Stationary Distributions

    Science.gov (United States)

    Fedotov, A. V.; Gluckstern, R. L.; Kurennoy, S. S.; Ryne, R. D.

    1998-04-01

    We have constructed, analytically and numerically, a new class of self-consistent 6-D phase space stationary distributions. The beam is then mismatched longitudinally and/or transversely, and we explore the formation of longitudinal and transverse halos in 3-D axisymmetric beam bunches. The longitudinal phase space clearly shows the typical "peanut" diagram observed in 2-D calculations. We find that the longitudinal halo forms first for comparable longitudinal and transverse mismatches because the longitudinal tune depression is more severe than the transverse one for elongated bunches. Of particular importance is the coupling between longitudinal and transverse motion and its effect on halo formation.

  14. Overview of Alternative Bunching and Current-shaping Techniques for Low-Energy Electron Beams

    Energy Technology Data Exchange (ETDEWEB)

    Piot, Philippe [Northern Illinois U.

    2015-12-01

    Techniques to bunch or shape an electron beam at low energies (E <15 MeV) have important implications toward the realization of table-top radiation sources [1] or to the design of compact multi-user free-electron lasers[2]. This paper provides an overview of alternative methods recently developed including techniques such as wakefield-based bunching, space-charge-driven microbunching via wave-breaking [3], ab-initio shaping of the electron-emission process [4], and phase space exchangers. Practical applications of some of these methods to foreseen free-electron-laser configurations are also briefly discussed [5].

  15. A periodically-switched ODE model for N-bunch beamloading in a storage ring.

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, C.

    1999-04-20

    A new baseband formulation of the coupled cavity/longitudinal-bunch ODEs is derived. Assuming linearity, a model of the form {dot x}(t) = A(t)x(t) + B(t)u(t) arises, where A(t) and B(t) are piecewise constant, and periodic with the revolution period T{sub 0}. Such models, known in the control community as (periodic) switched systems, have known (in)stability criteria and control theoretic properties, which can be useful in the analysis and control of multiple bunch beamloading.

  16. Electro-optical bunch length measurements at the ANKA storage ring - First lessons learned

    Energy Technology Data Exchange (ETDEWEB)

    Hiller, Nicole; Borysenko, Andrii; Hertle, Edmund; Huttel, Erhard; Judin, Vitali; Marsching, Sebastian; Mueller, Anke-Susanne; Nasse, Michael J.; Schuh, Marcel [Karlsruher Institut fuer Technologie (KIT), Karlsruhe (Germany)

    2013-07-01

    A set up for near-field electro optical bunch length measurements has recently been installed into the UHV system of the ANKA storage ring. For electro-optical bunch length measurements during ANKA's low alpha operation a laser pulse is used to probe the field induced birefringence in an electro-optical crystal (GaP in our case). The setup allows for both, electro-optical sampling (EOS, multi-shot) and spectral decoding (EOSD, single- and multi-shot) measurements. This talk presents first results and discusses challenges that needed to be overcome in order for this method to work at storage rings.

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

    Science.gov (United States)

    Burov, Alexey

    2016-08-01

    Which gain and phase have to be set for a bunch-by-bunch transverse damper, and at which chromaticity is it better to stay? These questions are considered for three models: the two-particle model with possible quadrupole wake, the author's nested head-tail (NHT) model with the broadband impedance, and the NHT with the LHC impedance model. Details of 2D areas of stability in the chromaticity-intensity and chromaticity-gain planes and possibilities to use them are discussed. It is shown that resistive feedbacks may generate asymmetry of the tune shift distribution, which requires positively-shifted stability diagrams.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-05-03

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

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

    OpenAIRE

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

    2011-01-01

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

  20. Terahertz coherent transition radiation based on an ultrashort electron bunching beam

    Science.gov (United States)

    Liu, Wen-Xin; Huang, Wen-Hui; Du, Ying-Chao; Yan, Li-Xin; Wu, Dai; Tang, Chuan-Xiang

    2011-07-01

    The experimental result of terahertz (THz) coherent transition radiation generated from an ultrashort electron bunching beam is reported. During this experiment, the window for THz transmission from ultrahigh vacuum to free air is tested. The compact measurement system which can simultaneously test the THz wave power and frequency is built and proofed. With the help of improved Martin—Puplett interferometer and Kramers—Krong transform, the longitudinal bunch length is measured. The results show that the peak power of THz radiation wave is more than 80 kW, and its radiation frequency is from 0.1 THz to 1.5 THz.

  1. Plasma gradient controlled injection and postacceleration of high quality electron bunches

    Energy Technology Data Exchange (ETDEWEB)

    Geddes, Cameron G.R.; Nakamura, Kei; Plateau, Guillaume R.; Toth, Csaba; Cormier-Michel, Estelle; Esarey, Eric; Schroeder, Carl B.; Cary, John R.; Leemans, Wim P.; Bruhwiler, D.L.

    2008-10-15

    Plasma density gradients in a gas jet were used to control the wake phase velocity and trapping threshold in a laser wakefield accelerator, producing stable electron bunches with longitudinal and transverse momentum spreads more than 10 times lower than in previous experiments (0.17 and 0.02 MeV=c FWHM, respectively) and with central momenta of 0.76 +- 0.02 MeV=c. Transition radiation measurements combined with simulations indicated that the bunches can be used as a wakefieldaccelerator injector to produce stable beams with 0.2 MeV=c-class momentum spread at high energies.

  2. Quasimonoenergetic and low emittance ion bunch generation from ultrathin targets by counterpropagating laser pulses of ultrarelativistic intensities

    CERN Document Server

    Avetissian, H K; Mkrtchian, G F; Sedrakian, Kh V

    2011-01-01

    A new method for generation of quasimonoenergetic and low emittance fast ion/nuclei bunches of solid densities from nanotargets by two counterpropagating laser pulses of ultrarelativistic intensities is proposed, based on the threshold phenomenon of particles "reflection" due to induced nonlinear Compton scattering. Particularly, a setup is considered which provides generation of ion bunches with parameters that are required in hadron therapy.

  3. Emittance growth due to static and radiative space charge forces in an electron bunch compressor

    Science.gov (United States)

    Talman, Richard; Malitsky, Nikolay; Stulle, Frank

    2009-01-01

    Evolution of short intense electron bunches passing through bunch-compressing beam lines is studied using the UAL (Unified Accelerator Libraries) string space charge formulation [R. Talman, Phys. Rev. ST Accel. Beams 7, 100701 (2004)PRABFM1098-440210.1103/PhysRevSTAB.7.100701; N. Malitsky and R. Talman, in Proceedings of the 9th European Particle Accelerator Conference, Lucerne, 2004 (EPS-AG, Lucerne, 2004); R. Talman, Accelerator X-Ray Sources (Wiley-VCH, Weinheim, 2006), Chap. 13]. Three major configurations are studied, with the first most important and studied in greatest detail (because actual experimental results are available and the same results have been simulated with other codes): (i) Experimental bunch compression results were obtained at CTF-II, the CERN test facility for the “Compact Linear Collider” using electrons of about 40 MeV. Previous simulations of these results have been performed (using TraFiC4* [A. Kabel , Nucl. Instrum. Methods Phys. Res., Sect. A 455, 185 (2000)NIMAER0168-900210.1016/S0168-9002(00)00729-4] and ELEGANT [M. Borland, Argonne National Laboratory Report No. LS-287, 2000]). All three simulations are in fair agreement with the data except that the UAL simulation predicts a substantial dependence of horizontal emittance γx on beam width (as controlled by the lattice βx function) at the compressor location. This is consistent with the experimental observations, but inconsistent with other simulations. Excellent agreement concerning dependence of bunch energy loss on bunch length and magnetic field strength [L. Groening , in Proceedings of the Particle Accelerator Conference, Chicago, IL, 2001 (IEEE, New York, 2001), http://groening.home.cern/groening/csr_00.htm] confirms our understanding of the role played by coherent synchrotron radiation (CSR). (ii) A controlled comparison is made between the predictions of the UAL code and those of CSRTrack [M. Dohlus and T. Limberg, in Proceedings of the 2004 FEL Conference, pp. 18

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-06-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-08-31

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

  6. Coherent-Radiation Spectroscopy of Few-Femtosecond Electron Bunches Using a Middle-Infrared Prism Spectrometer

    Science.gov (United States)

    Maxwell, T. J.; Behrens, C.; Ding, Y.; Fisher, A. S.; Frisch, J.; Huang, Z.; Loos, H.

    2013-11-01

    Modern, high-brightness electron beams such as those from plasma wakefield accelerators and free-electron laser linacs continue the drive to ever-shorter bunch durations. In low-charge operation (˜20pC), bunches shorter than 10 fs are reported at the Linac Coherent Light Source (LCLS). Though suffering from a loss of phase information, spectral diagnostics remain appealing as compact, low-cost bunch duration monitors suitable for deployment in beam dynamics studies and operations instrumentation. Progress in middle-infrared (MIR) imaging has led to the development of a single-shot, MIR prism spectrometer to characterize the corresponding LCLS coherent beam radiation power spectrum for few-femtosecond scale bunch length monitoring. In this Letter, we report on the spectrometer installation as well as the temporal reconstruction of 3 to 60 fs-long LCLS electron bunch profiles using single-shot coherent transition radiation spectra.

  7. Delignification outperforms alkaline extraction for xylan fingerprinting of oil palm empty fruit bunch

    NARCIS (Netherlands)

    Murciano Martínez, Patricia; Kabel, Mirjam A.; Gruppen, Harry

    2016-01-01

    Enzyme hydrolysed (hemi-)celluloses from oil palm empty fruit bunches (EFBs) are a source for production of bio-fuels or chemicals. In this study, after either peracetic acid delignification or alkaline extraction, EFB hemicellulose structures were described, aided by xylanase hydrolysis. Deligni

  8. A new method to generate relativistic comb bunches with tunable subpicosecond spacing

    International Nuclear Information System (INIS)

    We propose and analyze a scheme to produce comb bunches, i.e. a bunch consisting of micro-bunch trains, with tunable subpicosecond spacing. In the scheme, the electron beam is first deflected by a deflecting cavity which introduces a longitudinal-dependent linear transverse kick to the particles. After passing through a drift space, the transverse beam size is linearly coupled to the longitudinal position of the particle inside the beam, and a mask is placed there to tailor the beam, then the mask distribution is imprinted on the beam's longitudinal distribution. A quadrupole magnet and another deflecting cavity are used in the beam line to compensate the transverse angle due to the first deflecting cavity. Analysis shows that the number, length, and spacing of the trains can be controlled through the parameters of the deflecting cavity and the mask. Such electron bunch trains can be applied to an infrared free electron laser, a plasma-wakefield accelerator and a supper-radiance THz source. (authors)

  9. Laser Gate: Multi-MeV electron acceleration and zeptosecond e-bunching

    OpenAIRE

    Kaplan, A. E.; Pokrovsky, A. L.

    2009-01-01

    Relativistically-intense laser beam with large field gradient ("laser gate") enables strong inelastic scattering of electrons crossing the beam. This process allows for multi-MeV electron net acceleration per pass within the wavelength space. Inelastic scattering even in low-gradient laser field may also induce extremely tight temporal focusing and electron bunch formation down to quantum, zepto-second limit.

  10. Ralph Bunche's International Legacy: The Middle East, Congo, and United Nations Peacekeeping

    Science.gov (United States)

    Lyman, Princeton N.

    2004-01-01

    Ralph Bunche is remembered most for three major achievements in the international field. His mediation of the end of the first Israel-Arab war, for which he won the Nobel Peace Prize; his work in the tumultuous period of independence in the Congo; and his "invention" of United Nations peacekeeping, which itself won the Nobel Peace Prize in 1950.…

  11. Measurements of bunch length and shape at the ANKA storage ring

    Energy Technology Data Exchange (ETDEWEB)

    Hiller, Nicole; Fitterer, Miriam; Hillenbrand, Steffen; Huttel, Erhard; Hofmann, Andre; Judin, Vitali; Klein, Marit; Marsching, Sebastian; Mueller, Anke-Susanne; Plech, Anton; Smale, Nigel; Sonnad, Kiran [Karlsruhe Institute of Technology, Karlsruhe (Germany); Bruendermann, Erik; Krueger, Matthias [Physikalische Chemie II, Ruhr University, Bochum (Germany); Tavares Fernandes, Pedro [Karlsruhe Institute of Technology, Karlsruhe (Germany); Brazilian Synchrotron Light Laboratory (LNLS) (Brazil)

    2010-07-01

    Various methods are in use at the ANKA storage ring to determine the length and, if possible, the shape of the electron bunches. This presentation gives an overview of the different methods and studies performed. Emphasis will be put on streak camera measurements and the technique of intensity autocorrelation with semi-conductor detectors.

  12. Simulation of ELBE SRF gun II for high-bunch-charge applications

    Science.gov (United States)

    Lu, P.; Arnold, A.; Teichert, J.; Vennekate, H.; Xiang, R.

    2016-09-01

    The SRF gun at ELBE will benefit most of the local user beamlines for future high-bunch-charge operations. Parallel to its development, simulation-based investigations have been performed to improve the beam quality for THz experiments and Compton backscattering experiments. These two applications have the most challenging requirements: THz experiments benefit significantly from short bunch lengths at the sub-ps level, while Compton backscattering experiments demand small transverse beam sizes of about 30 μm. The beam dynamics of the SRF gun are simulated with ASTRA and the beam transport is optimized using Elegant. Important physical effects included in simulations are introduced first, where the interesting phenomenon of "slice mismatch" is generally quantified and numerically studied. Afterwards, beam transport strategies and optimization methods are proposed which are based on the specific settings of ELBE but also applicable to similar accelerator setups. Finally, optimizations of the SRF gun and the beam transport in ELBE are presented. Results show that the SRF gun is capable of providing 500 pC bunches for both applications with better beam qualities than the currently 100 pC bunches supplied by the existing thermionic DC source.

  13. Towards highest peak intensities for ultra-short MeV-range ion bunches

    Science.gov (United States)

    Busold, Simon; Schumacher, Dennis; Brabetz, Christian; Jahn, Diana; Kroll, Florian; Deppert, Oliver; Schramm, Ulrich; Cowan, Thomas E.; Blažević, Abel; Bagnoud, Vincent; Roth, Markus

    2015-07-01

    A laser-driven, multi-MeV-range ion beamline has been installed at the GSI Helmholtz center for heavy ion research. The high-power laser PHELIX drives the very short (picosecond) ion acceleration on μm scale, with energies ranging up to 28.4 MeV for protons in a continuous spectrum. The necessary beam shaping behind the source is accomplished by applying magnetic ion lenses like solenoids and quadrupoles and a radiofrequency cavity. Based on the unique beam properties from the laser-driven source, high-current single bunches could be produced and characterized in a recent experiment: At a central energy of 7.8 MeV, up to 5 × 108 protons could be re-focused in time to a FWHM bunch length of τ = (462 ± 40) ps via phase focusing. The bunches show a moderate energy spread between 10% and 15% (ΔE/E0 at FWHM) and are available at 6 m distance to the source und thus separated from the harsh laser-matter interaction environment. These successful experiments represent the basis for developing novel laser-driven ion beamlines and accessing highest peak intensities for ultra-short MeV-range ion bunches.

  14. Comparative Study of Bunch Length And Arrival Time Measurements at FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Schlarb, H.; Azima, A.; Dusterer, S.; Huning, M.; Knabbe, E.A.; Roehrs, M.; Rybnikov, V.; Schmidt, B.; Steffen, B.; /DESY; Ross, M.C.; /SLAC; Schmueser, P.; Winter, A.; /Hamburg U.

    2007-04-16

    Diagnostic devices to precisely measure the longitudinal electron beam profile and the bunch arrival time require elaborate new instrumentation techniques. At FLASH, two entirely different methods are used. The bunch profile can be determined with high precision by a transverse deflecting RF structure, but the method is disruptive and does not allow to monitor multiple bunches in a macro-pulse train. It is therefore complemented by two non-disruptive electrooptical devices, called EO and TEO. The EO setup uses a dedicated diagnostic laser synchronized to the machine RF. The longitudinal electron beam profile is encoded in the intensity profile of a chirped laser pulse and analyzed by looking at the spectral composition of the pulse. The second setup, TEO, utilizes the TiSa-based laser system used for pump-probe experiments. Here, the temporal electron shape is encoded into the spatial dimension of the laser pulse by an intersection angle between the laser and the electron beam at the EO-crystal. In this paper, we present a comparative study of bunch length and arrival time measurements performed simultaneously with all three experimental techniques.

  15. Parallel Beam-Beam Simulation Incorporating Multiple Bunches and Multiple Interaction Regions

    CERN Document Server

    Jones, F W; Pieloni, T

    2007-01-01

    The simulation code COMBI has been developed to enable the study of coherent beam-beam effects in the full collision scenario of the LHC, with multiple bunches interacting at multiple crossing points over many turns. The program structure and input are conceived in a general way which allows arbitrary numbers and placements of bunches and interaction points (IP's), together with procedural options for head-on and parasitic collisions (in the strong-strong sense), beam transport, statistics gathering, harmonic analysis, and periodic output of simulation data. The scale of this problem, once we go beyond the simplest case of a pair of bunches interacting once per turn, quickly escalates into the parallel computing arena, and herein we will describe the construction of an MPI-based version of COMBI able to utilize arbitrary numbers of processors to support efficient calculation of multi-bunch multi-IP interactions and transport. Implementing the parallel version did not require extensive disruption of the basic ...

  16. Distinct physiological responses underlie defoliation tolerance in African lawn and bunch grasses

    NARCIS (Netherlands)

    Anderson, T.M.; Kumordzi, B.B.; Fokkema, W.; Valls Fox, H.; Olff, H.

    2013-01-01

    Premise of research. African grass communities are dominated by two distinct functional types: tall, caespitose bunch grasses and short, spreading lawn grasses. Functional type coexistence has been explained by differences in defoliation tolerance, because lawn grasses occur in intensively grazed ar

  17. Theory of superradiance of electron bunch moving in waveguide under group synchronism condition

    CERN Document Server

    Ginzburg, N S; Sergeev, A S

    2000-01-01

    Theory of wiggler superradiance of electron bunch moving in waveguide under group synchronism condition is presented. It is shown that in the reference frame moving with electrons emission occurs at a quasi cut-off frequency. The theory is based on parabolic equation for description of wave profile evolution. Comparison with experimental results is discussed.

  18. Transverse self-fields within an electron bunch moving in an arc of a circle

    CERN Document Server

    Geloni, G A; Luiten, J; Van der Wiel, M J; Dohlus, M; Saldin, E L; Schneidmiller, E A; Yurkov, M; Geloni, Gianluca; Botman, Jan; Luiten, Jom; Wiel, Marnix van der; Dohlus, Martin; Saldin, Evgeni; Schneidmiller, Evgeni; Yurkov, Mikhail

    2004-01-01

    As a consequence of motions driven by external forces, self-fields (which are different from the static case) originate within an electron bunch. In the case of magnetic external forces acting on an ultrarelativistic beam, the longitudinal self-interactions are responsible for CSR (Coherent Synchrotron Radiation)-related phenomena, which have been studied extensively. On the other hand, transverse self-interactions are present too. At the time being, existing theoretical analysis of transverse self-forces deal with the case of a bunch moving along a circular orbit only, without considering the situation of a bending magnet with a finite length. In this paper we propose an electrodynamical analysis of transverse self-fields which originate, at the position of a test particle, from an ultrarelativistic electron bunch moving in an arc of a circle. The problem will be first addressed within a two-particle system. We then extend our consideration to a line bunch with a stepped density distribution, a situation whi...

  19. Dilute Ionic Liquids Pretreatment of Palm Empty Bunch and Its Impact to Produce Bioethanol

    Directory of Open Access Journals (Sweden)

    Lucy Arianie

    2014-06-01

    Full Text Available Ethanol production through ionic liquids pretreatment of palm empty bunch (PEB was carried out. This research aims to investigate impact of ionic liquids synthetic i.e 1-butyl- 3-methyl imidazoliumbromide or [BMIM]bromide toward cellulose’s palm empty bunch and convert its cellulose into bioethanol. Ionic liquid was synthesized through reflux and microwave assisted synthesis methods. Research investigation showed that microwave assisted synthesis produce [BMIM]bromide 90% faster than reflux method. The characterization of synthesized product using FTIR, 1H-NMR, 13C-NMR and LC-MS showed that these reactions have been carried out successfully. Scanning electron microscope figure out changes morphological surface of palm empty bunch caused by ionic liquid pretreatment. Crystallinity index of PEB milled and cellulose of PEFB after [BMIM]bromide dissolution were identified using comparison of PEB FTIR spectrum. Cellulose without dilute [BMIM]bromide have higher LOI number than cellulose after [BMIM]bromide dissolution. It indicated that a large part of cellulose after dissolution has been changed into amorf. Hydrolysis residue of palm empty bunch hydrolyzed by sulfuric acids 5%, 100 0C for 5 hours and produce 685 ppm of reducing sugar. Simultaneous Saccharification and Fermentation using Trichoderma viride and Saccharomyce cerevisiae for 5 days produce 0,69% of bioethanol.

  20. TADPOLE for longitudinal electron-bunch diagnostics based on electro-optic upconversion

    Energy Technology Data Exchange (ETDEWEB)

    Schwinkendorf, Jan-Patrick, E-mail: jan-patrick.schwinkendorf@desy.de; Wunderlich, Steffen, E-mail: steffen.wunderlich@desy.de; Schaper, Lucas; Schmidt, Bernhard; Osterhoff, Jens

    2014-03-11

    Electron-bunch diagnostics are desired to utilize unambiguous, non-destructive, single-shot techniques. Various methods fulfill the latter two demands, but feature significant ambiguities and constraints in the reconstruction of time-domain electron-bunch profiles, e.g. uncertainties arising from the phase retrieval of coherent radiation using the Kramers–Kronig relation. We present a novel method of measuring the spectral phase. The measurement is based on upconversion in an electro-optic crystal, where the THz-field spectrum of fs-electron bunches is shifted to the near-infrared. This technique allows the single-shot detection of its longitudinal form factor in both, amplitude and phase. The spectral phase and amplitude information is measured and thus the temporal profile reconstructed using temporal analysis by dispersing a pair of light E-fields, also known as TADPOLE. This is a combination of frequency resolved optical gating (FROG) and spectral interferometry, enabling the temporal measurement of low-power laser pulses. In this procedure, a narrow-bandwidth laser pulse detecting the longitudinal variations in the transverse electric field of an electron bunch via frequency mixing is interfered with a broadband and FROG-characterized reference pulse. The longitudinal beam profile may therefore be unambiguously inferred from the generated interferogram and the detected spectral-phase-information of the reference pulse.

  1. TADPOLE for longitudinal electron-bunch diagnostics based on electro-optic upconversion

    Energy Technology Data Exchange (ETDEWEB)

    Schwinkendorf, Jan-Patrick; Wunderlich, Steffen; Schmidt, Bernhard; Osterhoff, Jens [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2013-07-01

    Electron-bunch diagnostics are desired to utilize unambiguous, non-destructive, single-shot techniques. Various methods fulfill the latter two demands, but feature significant ambiguities and constraints in the reconstruction of a time-domain electron-bunch profile, as for example uncertainties due to the phase retrieval of coherent radiation using the Kramers-Kronig relation. We present a novel method of upconverting the THz-field spectrum of fs electron bunches at the free-electron laser FLASH into the near-infrared in an electro-optic crystal. This technique allows the single-shot detection of its longitudinal form factor in both, amplitude and phase. The spectral phase and amplitude information is measured and thus the temporal profile reconstructed using temporal analysis by dispersing a pair of light E-fields, also known as TADPOLE. This is a combination of frequency resolved optical gating (FROG) and spectral interferometry, which enables the temporal measurement of low-power laser pulses. In this experiment, a narrow-bandwidth laser pulse detecting the longitudinal electric field of an electron bunch is interfered with a broadband and FROG-characterized reference pulse. The longitudinal beam profile may therefore be unambiguously inferred from the generated interferogram and the detected spectral-phase-information of the reference pulse.

  2. Single-shot electron bunch length measurements using a spatial electro-optical autocorrelation interferometer

    International Nuclear Information System (INIS)

    A spatial, electro-optical autocorrelation (EOA) interferometer using the vertically polarized lobes of coherent transition radiation (CTR) has been developed as a single-shot electron bunch length monitor at an optical beam port downstream the 100 MeV preinjector LINAC of the Swiss Light Source. This EOA monitor combines the advantages of step-scan interferometers (high temporal resolution) [D. Mihalcea et al., Phys. Rev. ST Accel. Beams 9, 082801 (2006) and T. Takahashi and K. Takami, Infrared Phys. Technol. 51, 363 (2008)] and terahertz-gating technologies [U. Schmidhammer et al., Appl. Phys. B: Lasers Opt. 94, 95 (2009) and B. Steffen et al., Phys. Rev. ST Accel. Beams 12, 032802 (2009)] (fast response), providing the possibility to tune the accelerator with an online bunch length diagnostics. While a proof of principle of the spatial interferometer was achieved by step-scan measurements with far-infrared detectors, the single-shot capability of the monitor has been demonstrated by electro-optical correlation of the spatial CTR interference pattern with fairly long (500 ps) neodymium-doped yttrium aluminum garnet (Nd:YAG) laser pulses in a ZnTe crystal. In single-shot operation, variations of the bunch length between 1.5 and 4 ps due to different phase settings of the LINAC bunching cavities have been measured with subpicosecond time resolution.

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

    Directory of Open Access Journals (Sweden)

    Rajinda Senaratne

    2009-08-01

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

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

    Science.gov (United States)

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

    2016-07-01

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

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

    International Nuclear Information System (INIS)

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

  6. Factors associated with the allocation of carbohydrates to bunch dry matter production in oil palm.

    NARCIS (Netherlands)

    Breure, C.J.

    1987-01-01

    This thesis reports on the factors relevant to the allocation of assimilates to oil palm bunch dry matter (DM) production, based on an extensive set of growth and yield records from experiments in Papua New Guinea and Malaysia.Basically, assimilates from gross assimilation of the canopy are first us

  7. Dilute Ionic Liquids Pretreatment of Palm Empty Bunch and Its Impact to Produce Bioethanol

    Directory of Open Access Journals (Sweden)

    Lucy Arianie

    2013-12-01

    Full Text Available Ethanol production through ionic liquids pretreatment of palm empty bunch (PEB was carried out. This research aims to investigate impact of ionic liquids synthetic i.e 1-butyl-3-methyl imidazoliumbromide or [BMIM]bromide toward cellulose’s palm empty bunch and convert its cellulose into bioethanol. Ionic liquid was synthesized  through reflux and microwave assisted synthesis methods. Research investigation showed that microwave assisted synthesis produce [BMIM]bromide 90% faster than reflux method. The characterization of synthesized product using FTIR, 1H-NMR, 13C-NMR and LC-MS showed that these reactions have been carried out successfully. Scanning electron microscope figure out changes morphological surface of palm empty bunch caused by ionic liquid pretreatment. Crystallinity index of PEB milled and cellulose of PEFB after [BMIM]bromide dissolution were identified using comparison of PEB FTIR spectrum. Cellulose without dilute [BMIM]bromide have higher LOI number than cellulose after [BMIM]bromide dissolution. It indicated that a large part of cellulose after dissolution has been changed into amorf. Hydrolysis residue of palm empty bunch hydrolyzed by sulfuric acids 5%, 100 0C for 5 hours and produce 685 ppm of reducing sugar. Simultaneous Saccharification and Fermentation using Trichoderma viride and Saccharomyce cerevisiae  for 5 days produce 0,69% of bioethanol.

  8. Sub-femtosecond electron bunches created by direct laser acceleration in a laser wakefield accelerator with ionization injection

    CERN Document Server

    Lemos, N; Marsh, K A; Joshi, C

    2015-01-01

    In this work, we will show through three-dimensional particle-in-cell simulations that direct laser acceleration in laser a wakefield accelerator can generate sub-femtosecond electron bunches. Two simulations were done with two laser pulse durations, such that the shortest laser pulse occupies only a fraction of the first bubble, whereas the longer pulse fills the entire first bubble. In the latter case, as the trapped electrons moved forward and interacted with the high intensity region of the laser pulse, micro-bunching occurred naturally, producing 0.5 fs electron bunches. This is not observed in the short pulse simulation.

  9. Electron diffraction using ultrafast electron bunches from a laser-wakefield accelerator at kHz repetition rate

    Science.gov (United States)

    He, Z.-H.; Thomas, A. G. R.; Beaurepaire, B.; Nees, J. A.; Hou, B.; Malka, V.; Krushelnick, K.; Faure, J.

    2013-02-01

    We show that electron bunches in the 50-100 keV range can be produced from a laser wakefield accelerator using 10 mJ, 35 fs laser pulses operating at 0.5 kHz. It is shown that using a solenoid magnetic lens, the electron bunch distribution can be shaped. The resulting transverse and longitudinal coherence is suitable for producing diffraction images from a polycrystalline 10 nm aluminum foil. The high repetition rate, the stability of the electron source, and the fact that its uncorrelated bunch duration is below 100 fs make this approach promising for the development of sub-100 fs ultrafast electron diffraction experiments.

  10. Electron diffraction using ultrafast electron bunches from a laser-wakefield accelerator at kHz repetition rate

    International Nuclear Information System (INIS)

    We show that electron bunches in the 50–100 keV range can be produced from a laser wakefield accelerator using 10 mJ, 35 fs laser pulses operating at 0.5 kHz. It is shown that using a solenoid magnetic lens, the electron bunch distribution can be shaped. The resulting transverse and longitudinal coherence is suitable for producing diffraction images from a polycrystalline 10 nm aluminum foil. The high repetition rate, the stability of the electron source, and the fact that its uncorrelated bunch duration is below 100 fs make this approach promising for the development of sub-100 fs ultrafast electron diffraction experiments.

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

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

    CERN Document Server

    Pivi, M T

    2003-01-01

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

  14. DESIGN AND INITIAL RESULTS OF A TURN-BY-TURN BEAM POSITION MONITORING SYSTEM FOR MULTIPLE BUNCH OPERATION OF THE ATF DAMPING RING

    CERN Document Server

    Christian, G B; Bett, D R; Burrows, P N; Davis, M R; Gerbershagen, A; Perry, C; Constance, B; Resta-Lopez, J

    2011-01-01

    An FPGA-based monitoring system has been developed to study multi-bunch beam instabilities in the damping ring (DR) of the KEK Accelerator Test Facility (ATF), utilising a stripline beam position monitor (BPM) and existing BPM processor hardware. The system is designed to record the horizontal and/or vertical positions of up to three bunches in the DR in single-bunch multi-train mode or the head bunch of up to three trains in multi-bunch mode, with a bunch spacing of 5.6 ns. The FPGA firmware and data acquisition software were modified to record turn-by-turn data for up to six channels and 1–3 bunches in the DR. An overview of the system and initial results will be presented.

  15. A new technique for compression of tree bunches from young stands

    Energy Technology Data Exchange (ETDEWEB)

    Bergstroem, D.; Nordfjell, T. (The Department of Forest Resource Management, The Swedish University of Agriculture Science, Umeaa (Sweden)); Bergsten, U. (The Department of Forest Ecology and Management, The Swedish University of Agriculture Science, Umeaa (Sweden))

    2007-07-01

    Trees or parts of trees from young stands could provide valuable biomass for energy production. However, they are voluminous, resulting in low load densities and poor efficiencies for forwarder and subsequent handling operations. Furthermore, the fresh raw material generally has high proportions of foliage and, thus, high mineral (ash) contents, so much of the foliage should be left, evenly distributed in the stand after harvesting, if possible, in order to reduce losses of nutrients and improve the material's combustion parameters. The objective of the study reported here was to evaluate the potential utility of a new, prototype machine for compressing bunched trees from young stands. It uses aggressive feed rollers to break and flatten branches to compress bunches during processing, and substantially defoliates the bunched stems. In this study Pinus sylvestris trees of two size classes (A and B, with diameters at breast height, dbh, of 5-8 cm and 12-15 cm, respectively) were used to test the system. Trees were manually felled and gathered into bunches that were subsequently processed using the prototype. Bucking was done by hand, and the bucked trees were bundled by tightening nylon string with a force of 100 N around each bucked bunch at the root end, the middle and the top end. Samples of bunches were chipped and sub-samples were taken to measure their ash and moisture contents. The results showed that for type A bundles the compression technique caused an 11% reduction in weight (due to losses of needles and fine branches), an 0.3 % reduction in ash content and a 68% increase in bulk density. Corresponding figures for type B bundles were a 150/o decrease in weight, a 0.4 % decrease in ash content and a 150% increase in bulk density. The results show that the effects are greatest when processing larger trees. The tested equipment could be attached to a harvester head or mounted on a forwarder-crane. Alternatively, it could be mounted as a separate unit, e

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

    CERN Document Server

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

    2012-01-01

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

  17. Focusing and transport of high-intensity multi-MeV proton bunches from a compact laser-driven source

    Science.gov (United States)

    Busold, S.; Schumacher, D.; Deppert, O.; Brabetz, C.; Frydrych, S.; Kroll, F.; Joost, M.; Al-Omari, H.; Blažević, A.; Zielbauer, B.; Hofmann, I.; Bagnoud, V.; Cowan, T. E.; Roth, M.

    2013-10-01

    Laser ion acceleration provides for compact, high-intensity ion sources in the multi-MeV range. Using a pulsed high-field solenoid, for the first time high-intensity laser-accelerated proton bunches could be selected from the continuous exponential spectrum and delivered to large distances, containing more than 109 particles in a narrow energy interval around a central energy of 9.4 MeV and showing ≤30mrad envelope divergence. The bunches of only a few nanoseconds bunch duration were characterized 2.2 m behind the laser-plasma source with respect to arrival time, energy width, and intensity as well as spatial and temporal bunch profile.

  18. Observation, control and modal analysis of longitudinal coupled-bunch instabilities in the ALS via a digital feedback system

    International Nuclear Information System (INIS)

    The operation of a longitudinal multi-bunch damping system using digital signal processing techniques is shown via measurements from the LBL Advanced Light Source. The feedback system (developed for use by PEP-II, ALS and DAΦNE) uses a parallel array of signal processors to implement a bunch by bunch feedback system for sampling rates up to 500 MHz. The programmable DSP system allows feedback control as well as accelerator diagnostics. A diagnostic technique is illustrated which uses the DSP system to excite and then damp the beam. The resulting 12 ms time domain transient is Fourier analyzed to provide the simultaneous measurement of growth rates and damping rates of all unstable coupled-bunch beam modes

  19. Femtosecond timing-jitter between photo-cathode laser and ultra-short electron bunches by means of hybrid compression

    Science.gov (United States)

    Pompili, R.; Anania, M. P.; Bellaveglia, M.; Biagioni, A.; Castorina, G.; Chiadroni, E.; Cianchi, A.; Croia, M.; Di Giovenale, D.; Ferrario, M.; Filippi, F.; Gallo, A.; Gatti, G.; Giorgianni, F.; Giribono, A.; Li, W.; Lupi, S.; Mostacci, A.; Petrarca, M.; Piersanti, L.; Di Pirro, G.; Romeo, S.; Scifo, J.; Shpakov, V.; Vaccarezza, C.; Villa, F.

    2016-08-01

    The generation of ultra-short electron bunches with ultra-low timing-jitter relative to the photo-cathode (PC) laser has been experimentally proved for the first time at the SPARC_LAB test-facility (INFN-LNF, Frascati) exploiting a two-stage hybrid compression scheme. The first stage employs RF-based compression (velocity-bunching), which shortens the bunch and imprints an energy chirp on it. The second stage is performed in a non-isochronous dogleg line, where the compression is completed resulting in a final bunch duration below 90 fs (rms). At the same time, the beam arrival timing-jitter with respect to the PC laser has been measured to be lower than 20 fs (rms). The reported results have been validated with numerical simulations.

  20. Beam Dynamics and Pulse Duration Control During Final Beam Bunching in Driver System for Heavy Ion Inertial Fusion

    CERN Document Server

    Kikuchi, Takashi; Katayama, Takeshi; Kawata, Shigeo; Nakajima, Mitsuo; Someya, Tetsuo

    2005-01-01

    Beam dynamics is investigated by multi-particle simulations during a final beam bunching in a driver system for heavy ion inertial fusion (HIF). The longitudinal bunch compression causes the beam instability induced by the strong space charge effect. The multi-particle simulation can indicate the emittance growth due to the longitudinal bunch compression. Dependence in the beam pulse duration is also investigated for effective pellet implosion in HIF. Not only the spatial nonuniformity of the beam illumination, but also the errors of the beam pulse duration cause changes of implosion dynamics. The allowable regime of the beam pulse duration for the effective fusion output becomes narrow with decreasing the input beam energy. The voltage accuracy requirement at the beam velocity modulator is also estimated for the final beam bunching. It is estimated that the integrated voltage error is allowable as a few percent.

  1. UV pulse trains by α-BBO crystal stacking for the production of THz-rap-rate electron bunches

    Science.gov (United States)

    Yan, Li-Xin; Hua, Jian-Fei; Du, Ying-Chao; Huang, Yuan-Fang; You, Yan; Wang, Dan; Huang, Wen-Hui; Tang, Chuan-Xiang; Tang

    2012-08-01

    Ultrashort electron bunch trains can be used for plasma wake field acceleration (PWFA) to overcome the limit of transformer ratio of a single electron bunch, or high-power terahertz (Thz) radiation production by various radiation mechanisms. Basic facility for high-power THz radiation development based on ultrashort electron beam has been set up at accelerator lab of TUB. Using birefringent crystal serials, ultraviolet (UV) pulse shaping for photocathode radio frequency gun to produce THz-repetition-rate pulse train was realized. Driven by such pulses, ultrashort electron bunch train with picosecond (ps) spacing was obtained for THz production. Measurement of the stacked UV pulse trains was done by difference frequency generation (DFG), and the measured group velocity mismatch of α-BBO crystal at 266.7-nm wavelength was 0.8 ps/mm. This method may also be applied to form ramped electron bunch trains for PWFA.

  2. Parametric (quasi-Cherenkov) cooperative radiation produced by electron bunches in natural or photonic crystals

    CERN Document Server

    Anishchenko, S V

    2013-01-01

    We use numerical modeling to study the features of parametric (quasi-Cherenkov) cooperative radiation arising when an electron bunch passes through a crystal (natural or artificial) under the conditions of dynamical diffraction of electromagnetic waves in the presence of shot noise. It is shown that in both Laue and Bragg diffraction cases, parametric radiation consists of two strong pulses: one emitted at small angles with respect to the particle velocity direction and the other emitted at large angles to it. Under Bragg diffraction conditions, the intensity of parametric radiation emitted at small angles to the particle velocity direction reaches saturation at sufficiently smaller number of particles than the intensity of parametric radiation emitted at large angles. Under Laue diffraction conditions, every pulse contains two strong peaks, which are associated with the emission of electromagnetic waves at the front and back ends of the bunch. The presence of noise causes a chaotic signal in the interval bet...

  3. Tailored electron bunches with smooth current profiles for enhanced transformer ratios in beam-driven acceleration

    CERN Document Server

    Lemery, Francois

    2015-01-01

    Collinear high-gradient ${\\cal O} (GV/m)$ beam-driven wakefield methods for charged-particle acceleration could be critical to the realization of compact, cost-efficient, accelerators, e.g., in support of TeV-scale lepton colliders or multiple-user free-electron laser facilities. To make these options viable, the high accelerating fields need to be complemented with large transformer ratios $>2$, a parameter characterizing the efficiency of the energy transfer between a wakefield-exciting "drive" bunch to an accelerated "witness" bunch. While several potential current distributions have been discussed, their practical realization appears challenging due to their often discontinuous nature. In this paper we propose several alternative current profiles which are smooth which also lead to enhanced transformer ratios. We especially explore a laser-shaping method capable of generating one the suggested distributions directly out of a photoinjector and discuss a linac concept that could possible drive a dielectric ...

  4. Use of electronic space charge to accelerate, focus and bunch plasma ions for pellet fusion

    International Nuclear Information System (INIS)

    Prior experiments have shown that deep, nearly parabolic, potential wells can be created by the injection of electrons into a spherical diode. Furthermore, it has been demonstrated that a large fraction of the input power can be transferred from the electronic space charge to ion motion provided the electron collection probability is small. However, the instantaneous power required for pellet fusion is still beyond the capabilities of existing machines. By utilizing the spherically symmetric potential wells found previously, the instantaneous power delivered to a small target at the center can be magnified (or bunched) by factors of 10 to 100. The measurement of these potentials, the comparison with a realistic theory, and an extrapolation to higher voltages/energies will be presented. Recent experiments are described which imply that bunching is present in a planar diode. Although the experiments were performed at low voltages (kV), the extrapolation with constant perveance is straightforward

  5. Late-time structure of the Bunch-Davies de Sitter wavefunction

    Energy Technology Data Exchange (ETDEWEB)

    Anninos, Dionysios [Stanford Institute of Theoretical Physics, Stanford University, Stanford (United States); Anous, Tarek [Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge (United States); Freedman, Daniel Z. [Stanford Institute of Theoretical Physics, Stanford University, Stanford (United States); Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge (United States); Department of Mathematics, Massachusetts Institute of Technology, Cambridge (United States); Konstantinidis, George [Stanford Institute of Theoretical Physics, Stanford University, Stanford (United States)

    2015-11-30

    We examine the late time behavior of the Bunch-Davies wavefunction for interacting light fields in a de Sitter background. We use perturbative techniques developed in the framework of AdS/CFT, and analytically continue to compute tree and loop level contributions to the Bunch-Davies wavefunction. We consider self-interacting scalars of general mass, but focus especially on the massless and conformally coupled cases. We show that certain contributions grow logarithmically in conformal time both at tree and loop level. We also consider gauge fields and gravitons. The four-dimensional Fefferman-Graham expansion of classical asymptotically de Sitter solutions is used to show that the wavefunction contains no logarithmic growth in the pure graviton sector at tree level. Finally, assuming a holographic relation between the wavefunction and the partition function of a conformal field theory, we interpret the logarithmic growths in the language of conformal field theory.

  6. Halo formation in spheroidal bunches with self-consistent stationary distributions

    Energy Technology Data Exchange (ETDEWEB)

    Fedotov, A.V.; Gluckstern, R.L. [Univ. of Maryland, College Park, MD (United States); Kurennoy, S.S.; Ryne, R.D. [Los Alamos National Lab., NM (United States)

    1998-12-31

    A new class of self-consistent 6-D phase space stationary distributions is constructed both analytically and numerically. The beam is then mismatched longitudinally and/or transversely, and the authors explore the beam stability and halo formation for the case of 3-D axisymmetric beam bunches using particle-in-cell simulations. They concentrate on beams with bunch length-to-width ratios varying from 1 to 5, which covers the typical range of the APT linac parameters. They find that the longitudinal halo forms first for comparable longitudinal and transverse mismatches. An interesting coupling phenomenon -- a longitudinal or transverse halo is observed even for very small mismatches if the mismatch in the other plane is large -- is discovered.

  7. Longitudinal halo in beam bunches with self-consistent 6-D distributions

    Science.gov (United States)

    Gluckstern, R. L.; Fedotov, A. V.; Kurennoy, S. S.; Ryne, R. D.

    1998-11-01

    We have explored the formation of longitudinal and transverse halos in 3-D axisymmetric beam bunches by starting with a self-consistent 6-D phase space distribution. Stationary distributions allow us to study the halo development mechanism without being obscured by beam redistribution and its effect on halo formation. The beam is then mismatched longitudinally and/or transversely, and we explore the rate, intensity and spatial extent of the halos which form, as a function of the beam charge and the mismatches. We find that the longitudinal halo forms first because the longitudinal tune depression is more severe than the transverse one for elongated bunches and conclude that it plays a major role in halo formation.

  8. Tunable THz radiation source from dielectric loaded waveguide excited by nonrelativistic electron bunch trains

    Science.gov (United States)

    Li, Weiwei; He, Zhigang; Lu, Yalin; Huang, Ruixuan; Liu, Weihao; Jia, Qika; Wang, Lin

    2016-10-01

    We propose a novel scheme to generate a tunable narrow-band THz radiation. In this scheme, a train of laser pulses with THz repetition rate is used to drive a photocathode direct current (DC) gun, leading to the emission of a train of electron bunches. The electron bunch train is subsequently accelerated by the gun field and applied to selectively excite one of the modes in the dielectric loaded waveguide (DLW) structure, which is located downstream the DC gun. Thanks to the tunability of the repetition rate of laser pulses and the gun voltage, a tunable narrow-band THz radiation source can be obtained. This proposed source has the advantages of compactness, robustness and relatively high power.

  9. Electron Bunch Timing with Femtosecond Precision in a Superconducting Free-Electron Laser

    Science.gov (United States)

    Löhl, F.; Arsov, V.; Felber, M.; Hacker, K.; Jalmuzna, W.; Lorbeer, B.; Ludwig, F.; Matthiesen, K.-H.; Schlarb, H.; Schmidt, B.; Schmüser, P.; Schulz, S.; Szewinski, J.; Winter, A.; Zemella, J.

    2010-04-01

    High-gain free-electron lasers (FELs) are capable of generating femtosecond x-ray pulses with peak brilliances many orders of magnitude higher than at other existing x-ray sources. In order to fully exploit the opportunities offered by these femtosecond light pulses in time-resolved experiments, an unprecedented synchronization accuracy is required. In this Letter, we distributed the pulse train of a mode-locked fiber laser with femtosecond stability to different locations in the linear accelerator of the soft x-ray FEL FLASH. A novel electro-optic detection scheme was applied to measure the electron bunch arrival time with an as yet unrivaled precision of 6 fs (rms). With two beam-based feedback systems we succeeded in stabilizing both the arrival time and the electron bunch compression process within two magnetic chicanes, yielding a significant reduction of the FEL pulse energy jitter.

  10. Study of a magnetic alloy-loaded RF cavity for bunch compression at the CSR

    International Nuclear Information System (INIS)

    The Heavy Ion Research Facility and Cooling Storage Ring (HIRFL-CSR) accelerator in Lanzhou offers a unique possibility for the generation of high density and short pulse heavy ion beams by non-adiabatic bunch compression longitudinally, which is implemented by a fast jump of the RF-voltage amplitude. For this purpose, an RF cavity with high electric field gradient loaded with Magnetic Alloy cores has been developed. The results show that the resonant frequency range of the single-gap RF cavity is from 1.13 MHz to 1.42 MHz, and a maximum RF voltage of 40 kV with a total length of 100 cm can be obtained, which can be used to compress heavy ion beams of 238U72+ with 250 MeV/u from the initial bunch length of 200 ns to 50 ns with the coaction of the two single-gap RF cavity mentioned above. (authors)

  11. Demonstration of Cathode Emittance Dominated High Bunch Charge Beams in a DC gun-based Photoinjector

    CERN Document Server

    Gulliford, Colwyn; Bazarov, Ivan; Dunham, Bruce; Cultrera, Luca

    2015-01-01

    We present the results of transverse emittance and longitudinal current profile measurements of high bunch charge (greater than or equal to 100 pC) beams produced in the DC gun-based Cornell Energy Recovery Linac Photoinjector. In particular, we show that the cathode thermal and core beam emittances dominate the final 95% and core emittance measured at 9-9.5 MeV. Additionally, we demonstrate excellent agreement between optimized 3D space charge simulations and measurement, and show that the quality of the transverse laser distribution limits the optimal simulated and measured emittances. These results, previously thought achievable only with RF guns, demonstrate that DC gun based photoinjectors are capable of delivering beams with sufficient single bunch charge and beam quality suitable for many current and next generation accelerator projects such as Energy Recovery Linacs (ERLs) and Free Electron Lasers (FELs).

  12. Demonstration of cathode emittance dominated high bunch charge beams in a DC gun-based photoinjector

    International Nuclear Information System (INIS)

    We present the results of transverse emittance and longitudinal current profile measurements of high bunch charge (≥100 pC) beams produced in the DC gun-based Cornell energy recovery linac photoinjector. In particular, we show that the cathode thermal and core beam emittances dominate the final 95% and core emittances measured at 9–9.5 MeV. Additionally, we demonstrate excellent agreement between optimized 3D space charge simulations and measurement, and show that the quality of the transverse laser distribution limits the optimal simulated and measured emittances. These results, previously thought achievable only with RF guns, demonstrate that DC gun based photoinjectors are capable of delivering beams with sufficient single bunch charge and beam quality suitable for many current and next generation accelerator projects such as Energy Recovery Linacs and Free Electron Lasers

  13. High Bandwidth Pickup Design for Bunch Arrival-time Monitors for Free-Electron Laser

    CERN Document Server

    Angelovski, Aleksandar; Hansli, Matthias; Penirschke, Andreas; Schnepp, Sascha M; Bousonville, Michael; Schlarb, Holger; Bock, Marie Kristin; Weiland, Thomas; Jakoby, Rolf

    2012-01-01

    In this paper, we present the design and realization of high bandwidth pickup electrodes with a cutoff frequency above 40 GHz. The proposed cone-shaped pickups are part of a bunch arrival-time monitor (BAM) designed for high (> 500 pC) and low (20 pC) bunch charge operation mode providing for a time resolution of less than 10 fs for both operation modes. The proposed design has a fast voltage response, low ringing, and a resonance-free spectrum. For assessing the influence of manufacturing tolerances on the performance of the pickups, an extensive tolerance study has been performed via numerical simulations. A non-hermetic model of the pickups was built for measurement and validation purposes. The measurement and simulation results are in good agreement and demonstrate the capability of the proposed pickup system to meet the given specifications.

  14. ACCELERATORS Study of a magnetic alloy-loaded RF cavity for bunch compression at the CSR

    Science.gov (United States)

    Yin, Da-Yu; Liu, Yong; Xia, Jia-Wen; Li, Peng; Zhao, Yong-Tao; Yang, Lei; Qi, Xin

    2010-12-01

    The Heavy Ion Research Facility and Cooling Storage Ring (HIRFL-CSR) accelerator in Lanzhou offers a unique possibility for the generation of high density and short pulse heavy ion beams by non-adiabatic bunch compression longitudinally, which is implemented by a fast jump of the RF-voltage amplitude. For this purpose, an RF cavity with high electric field gradient loaded with Magnetic Alloy cores has been developed. The results show that the resonant frequency range of the single-gap RF cavity is from 1.13 MHz to 1.42 MHz, and a maximum RF voltage of 40 kV with a total length of 100 cm can be obtained, which can be used to compress heavy ion beams of 238U72+ with 250 MeV/u from the initial bunch length of 200 ns to 50 ns with the coaction of the two single-gap RF cavity mentioned above.

  15. Matching sub-fs electron bunches for laser-driven plasma acceleration at SINBAD

    Science.gov (United States)

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

    2016-09-01

    We present theoretical and numerical studies of matching sub-femtosecond space-charge-dominated electron bunch into the Laser-plasma Wake Field Accelerator (LWFA) foreseen at the SINBAD facility. The longitudinal space-charge (SC) effect induced growths of the energy spread and longitudinal phase-space chirp are major issues in the matching section, which will result in bunch elongation, emittance growth and spot size dilution. In addition, the transverse SC effect would lead to a mismatch of the beam optics if it were not compensated for. Start-to-end simulations and preliminary optimizations were carried out in order to understand the achievable beam parameters at the entrance of the plasma accelerator.

  16. Late-time Structure of the Bunch-Davies De Sitter Wavefunction

    CERN Document Server

    Anninos, Dionysios; Freedman, Daniel Z; Konstantinidis, George

    2014-01-01

    We examine the late time behavior of the Bunch-Davies wavefunction for interacting light fields in a de Sitter background. We use perturbative techniques developed in the framework of AdS/CFT, and analytically continue to compute tree and loop level contributions to the Bunch-Davies wavefunction. We consider self-interacting scalars of general mass, but focus especially on the massless and conformally coupled cases. We show that certain contributions grow logarithmically in conformal time both at tree and loop level. We also consider gauge fields and gravitons. The four-dimensional Fefferman-Graham expansion of classical asymptotically de Sitter solutions is used to show that the wavefunction contains no logarithmic growth in the pure graviton sector at tree level. Finally, assuming a holographic relation between the wavefunction and the partition function of a conformal field theory, we interpret the logarithmic growths in the language of conformal field theory.

  17. Femtosecond probing of light-speed plasma wakefields by using a relativistic electron bunch

    CERN Document Server

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

    2016-01-01

    Relativistic wakes produced by intense laser or particle beams propagating through plasmas are being considered as accelerators for next generation of colliders and coherent light sources. Such wakes have been shown to accelerate electrons and positrons to several gigaelectronvolts (GeV), with a few percent energy spread and a high wake-to-beam energy transfer efficiency. However, complete mapping of electric field structure of the wakes has proven elusive. Here we show that a high-energy electron bunch can be used to probe the fields of such light-speed wakes with femtosecond resolution. The highly transient, microscopic wakefield is reconstructed from the density modulated ultra-short probe bunch after it has traversed the wake. This technique enables visualization of linear wakefields in low-density plasmas that can accelerate electrons and positrons beams. It also allows characterization of wakes in plasma density ramps critical for maintaining the beam emittance, improving the energy transfer efficiency ...

  18. Downramp-assisted underdense photocathode electron bunch generation in plasma wakefield accelerators

    CERN Document Server

    Knetsch, Alexander; Wittig, Georg; Groth, Henning; Xi, Yunfeng; Deng, Aihua; Rosenzweig, James Benjamin; Bruhwiler, David Leslie; Smith, Johnathan; Jaroszynski, Dino Anthony; Sheng, Zheng-Ming; Manahan, Grace Gloria; Xia, Guoxing; Jamison, Steven; Hidding, Bernhard

    2014-01-01

    It is shown that the requirements for high quality electron bunch generation and trapping from an underdense photocathode in plasma wakefield accelerators can be substantially relaxed through localizing it on a plasma density downramp. This depresses the phase velocity of the accelerating electric field until the generated electrons are in phase, allowing for trapping in shallow trapping potentials. As a consequence the underdense photocathode technique is applicable by a much larger number of accelerator facilities. Furthermore, dark current generation is effectively suppressed.

  19. Subpicosecond electron bunch train production using a phase-space exchange technique

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Y.-E.; /Fermilab; Piot, P.; /Fermilab /Northern Illinois U.; Johnson, A.S.; Lumpkin, A.H.; /Fermilab; Maxwell, T.J.; /Fermilab /Northern Illinois U.; Ruan, J.; Thurman-Keup, R.M.; /Fermilab

    2011-03-01

    Our recent experimental demonstration of a photoinjector electron bunch train with sub-picosecond structures is reported in this paper. The experiment is accomplished by converting an initially horizontal beam intensity modulation into a longitudinal phase space modulation, via a beamline capable of exchanging phase-space coordinates between the horizontal and longitudinal degrees of freedom. The initial transverse modulation is produced by intercepting the beam with a multislit mask prior to the exchange. We also compare our experimental results with numerical simulations.

  20. E-Cloud Drivent Single-Bunch Instabilities in PS2

    OpenAIRE

    Venturini, M.

    2010-01-01

    One of the proposals under consideration for future upgrades of the LHC injector complex entails the replacement of the PS with the PS2, a longer circumference and higher energy synchrotron, with electron cloud effects representing a potentially serious limitation to the achievement of the upgrade goals. We report on ongoing numerical studies aiming at estimating the e-cloud density threshold for the occurrence of single bunch instabilities.

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

    OpenAIRE

    Venturini, M.

    2012-01-01

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

  2. Sport cycling crashes on public roads, the influence of bunch riding and experience.

    OpenAIRE

    Wijlhuizen, G.J. & Gent, P. van

    2014-01-01

    Cycling is a popular but unsafe mode of transport in the Netherlands and the number of seriously injured bicyclists has increased significantly since 2006. A special subgroup is the population of sport cyclists who perform their sport on public roads. The number of road crashes with sport cyclists shows an increasing trend. The authors propose two factors which might contribute to this trend. First, bunch riding among sport cyclists, and second the inflow of cyclists with low experience. No e...

  3. Current status of the electro-optical bunch length monitor at ANKA

    Energy Technology Data Exchange (ETDEWEB)

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

    2012-07-01

    A setup for precise electro-optical bunch length measurements at the ANKA storage ring is currently assembled. It is based on the principle of spectral decoding and consists of a GaP-crystal and an Yb fiber laser. As the impedance is changed by introducing the crystal in the beam pipe the resulting wake fields have to be taken into account. In this talk we present the current status of the project and the first simulation results.

  4. POTENTIAL OF FINES AS REINFORCING FIBRES IN ALKALINE PEROXIDE PULP OF OIL PALM EMPTY FRUIT BUNCH

    OpenAIRE

    Nurul H. Kamaludin,; Arniza Ghazali,; Wan Daud Wanrosli

    2012-01-01

    Pulp from the alkaline peroxide mechanical pulping (APMP) of oil palm empty fruit bunch, EFB, was fractionated with varying mesh-size screens to examine the effects imposed by size-specific fines on the produced pulp network. Occurring mainly as a result of refining, fines elements with dimensions almost resembling EFB fibres were the long tube-like tapered vessels from the arrays of adjoined cell walls detached along the perforation lines. These fibrillated vessel elements constituting the P...

  5. Isolation, Characterization, and Application of Nanocellulose from Oil Palm Empty Fruit Bunch Fiber as Nanocomposites

    OpenAIRE

    Lani, N. S.; Ngadi, N.; A. Johari; Jusoh, M

    2014-01-01

    Nanocomposites, consisting of a polymeric matrix and nanosized elements as reinforcement, have attracted significant scientific attention because of their high mechanical performance. A large variety of nanocomposites have been prepared using bio-based materials as a matrix and nanoreinforcement, so that it can reduce the dependence on nondegradable products and move to a sustainable materials basis. The objective of this study was to isolate nanocellulose from empty fruit bunch (EFB) fiber a...

  6. A Review of Structural Performance of Oil Palm Empty Fruit Bunch Fiber in Polymer Composites

    OpenAIRE

    Reza Mahjoub; Jamaludin Bin Mohamad Yatim; Abdul Rahman Mohd. Sam

    2013-01-01

    According to environmental concerns and financial problems, natural fibers have become interesting and fascinating nowadays to be used as an industrial material and structural material for rehabilitating of structures. Oil palm empty fruit bunch fiber (OPF) is a natural fiber which is found a lot in tropical areas. Scientists have used OPF fiber with many types of resins such as epoxy, polypropylene, polyester, and phenol formaldehyde. Therefore, this paper focused on the properties of OPF fi...

  7. Extraction of a single soliton from a bunch of solitons generated by pulse breakup

    Science.gov (United States)

    Bello-Jimenez, Miguel A.; Kuzin, Evgeny A.; Pottiez, Olivier; Ibarra-Escamilla, Baldemar; Flores-Rosas, Ariel; Duran-Sanchez, Manuel

    2010-02-01

    Pulses propagating in the fiber with anomalous dispersion are broken up to the bunch of soliton. The extraction of an individual soliton from the bunch can be used for soliton generation and also for investigation of the process of the soliton formation. In this work we experimentally demonstrate that the NOLM allows extraction of an individual soliton. Earlier we have shown numerically that the NOLM has high transmission for the solitons with a range of durations while solitons with shorter and longer durations are rejected. The range of the durations with high transmission depends on the NOLM length and also can be moved by amplification of solitons before entering to the NOLM. In the experiment we launched 25-ps pulses with about 10 W of power to the 500-m single mode fiber with dispersion equal to 20 ps/nm-km. As a result of the pulse breakup, a bunch of solitons is formed at the fiber output. The resulting solitons are launched to the EDFA and then to the NOLM made from the 40-m of the same fiber. The NOLM parameters are adjusted to transmit the highest soliton in the bunch (about 50 W of power and 1 ps of duration according to theoretical estimations). In the experiment we detected at the NOLM output a single pulse with duration of 1.46 ps and autocorrelation function similar to that of the soliton. When a 1-km fiber was attached to the NOLM at the fiber output we detected a soliton with duration of 0.9 ps.

  8. DEGRADATION, MECHANO-PHYSICAL, AND MORPHOLOGICAL PROPERTIES OF EMPTY FRUIT BUNCH REINFORCED POLYESTER COMPOSITES

    OpenAIRE

    Abdul Khalil, H. P. S.; Irshad ul Haq Bhat; M. Y. Sartika

    2010-01-01

    This research aims to study the effects of degradation on mechanical, physical, and morphological properties of empty fruit bunch (EFB) fiber- reinforced polyester composites. The unsaturated polyester resin has been used to produce thermoset polymer composites. The reinforcing effect in composites was evaluated at various fiber loadings, including an overall fiber content (by weight) of 20% and 40%. The mechanical (tensile, flexural, and impact) and physical (density, moisture content, and w...

  9. Lie algebraic analysis for the nonlinear transport of intense bunched beam in electrostatic quadrupoles

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhuo; L(U) Jian-Qin

    2008-01-01

    In this paper, the nonlinear transport of intense bunched beams in electrostatic quadrupoles is analyzed using the Lie algebraic method, and the results are briefly presented of the linear matrix approximation and the second order correction of particle trajectory in the state space. Beam having K-V distribution and Gaussian distribution approximation are respectively considered. A brief discussion is also given of the total effects of the quadrupole and the space charge forces on the evolution of the beam envelope.

  10. Downramp-assisted underdense photocathode electron bunch generation in plasma wakefield accelerators

    OpenAIRE

    Knetsch, Alexander; Karger, Oliver; Wittig, Georg; Groth, Henning; Xi, Yunfeng; Deng, Aihua; Rosenzweig, James Benjamin; Bruhwiler, David Leslie; Smith, Johnathan; Jaroszynski, Dino Anthony; Sheng, Zheng-Ming; Manahan, Grace Gloria; Xia, Guoxing; Jamison, Steven; Hidding, Bernhard

    2014-01-01

    It is shown that the requirements for high quality electron bunch generation and trapping from an underdense photocathode in plasma wakefield accelerators can be substantially relaxed through localizing it on a plasma density downramp. This depresses the phase velocity of the accelerating electric field until the generated electrons are in phase, allowing for trapping in shallow trapping potentials. As a consequence the underdense photocathode technique is applicable by a much larger number o...

  11. Hybrid Fibre Polylactide Acid Composite with Empty Fruit Bunch: Chopped Glass Strands

    OpenAIRE

    K. Y. Tshai; A. B. Chai; Kong, I.; Hoque, M.E; Tshai, K. H.

    2014-01-01

    Hybrid polylactide acid (PLA) composites reinforced with palm empty fruit bunch (EFB) and chopped strand E-glass (GLS) fibres were investigated. The hybrid fibres PLA composite was prepared through solution casting followed by pelletisation and subsequent hot compression press into 1 mm thick specimen. Chloroform and dichloromethane were used as solvent and their effectiveness in dissolving PLA was reported. The overall fibre loading was kept constant at volume fraction, Vf, of 20% while the ...

  12. Extraction and Characterization of Fibres from the Stalk and Spikelets of Empty Fruit Bunch

    OpenAIRE

    Yakum Reneta Nafu; Josepha Foba-Tendo; Ebenezer Njeugna; Gossett Oliver; Kavian Omar Cooke

    2015-01-01

    Fibres from different parts of empty fruit bunch, which is a major solid waste from oil palm processing, were subjected to different pretreatments and characterised for variability in length and diameter, mechanical performance, and proximate and trace element composition. Morphology and surface composition of the fibres were determined using scanning electron microscopy with energy dispersive X-ray. The fibres were further treated with KOH-boric acid and characterized by Fourier transform in...

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

    Directory of Open Access Journals (Sweden)

    Tuba DİLMAÇÜNAL

    2011-11-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-07-01

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

  15. Photon antibunching and bunching in a ring-resonator waveguide quantum electrodynamics system.

    Science.gov (United States)

    Chen, Zihao; Zhou, Yao; Shen, Jung-Tsung

    2016-07-15

    We numerically investigate the photonic state generation and its nonclassical correlations in a ring-resonator waveguide quantum electrodynamics system. Specifically, we discuss photon antibunching and bunching in various scenarios, including the imperfect resonator with backscattering and dissipations. Our numerical results indicate that an imperfect ring resonator with backscattering can enhance the quality of antibunching. In addition, we also identify the quantum photonic halo phenomenon in the photon scattering dynamics and the shoulder effect in the second-order correlation function.

  16. Direct Bioconversion of Oil Palm Empty Fruit Bunches for Bioethanol Production By Solid State Bioconversion

    OpenAIRE

    Nassereldeen Ahmed Kabbashi; Md. Zahangir Alam; M. Fahrurrazi Tompang

    2010-01-01

    The bioethanol production was conducted by utilizing agriculture waste, palm oil empty fruit bunches (EFB) with the aid of T. harzianum and yeast, Saccharomyces cerevisiae using solid state bioconversion method. The compatibility of various fungal strains was done as to develop the direct bioconversion process of compatible mixed culture. Analyzes such ethanol estimation, reducing sugar and glucosamine as growth indicator were conducted in order to select the best experimented run for ...

  17. Factors associated with the allocation of carbohydrates to bunch dry matter production in oil palm.

    OpenAIRE

    Breure, C.J.

    1987-01-01

    This thesis reports on the factors relevant to the allocation of assimilates to oil palm bunch dry matter (DM) production, based on an extensive set of growth and yield records from experiments in Papua New Guinea and Malaysia.Basically, assimilates from gross assimilation of the canopy are first used for maintenance of existing biomass (maintenance respiration). The remaining assimilates are converted into structural DM production. Carbohydrate requirements for components of DM production ar...

  18. Photon antibunching and bunching in a ring-resonator waveguide quantum electrodynamics system.

    Science.gov (United States)

    Chen, Zihao; Zhou, Yao; Shen, Jung-Tsung

    2016-07-15

    We numerically investigate the photonic state generation and its nonclassical correlations in a ring-resonator waveguide quantum electrodynamics system. Specifically, we discuss photon antibunching and bunching in various scenarios, including the imperfect resonator with backscattering and dissipations. Our numerical results indicate that an imperfect ring resonator with backscattering can enhance the quality of antibunching. In addition, we also identify the quantum photonic halo phenomenon in the photon scattering dynamics and the shoulder effect in the second-order correlation function. PMID:27420523

  19. Longitudinal motion in bunch compression and in the external beam line

    International Nuclear Information System (INIS)

    Heavy ion fusion simulation experiments on the SNS synchrotron in the fields of; momentum spread increase during debunching, storage ring bunch compression experiments at 70.44 MeV, and, briefly, longitudinal motion in external beam line, were evaluated qualitatively. Certain features that need attention were noted but overall it was concluded that the proposed experiments on the SNS would yield considerable insight into HIF drivers. (U.K.)

  20. The Relationship Between Palm Oil Index Development and Mechanical Properties in the Ripening Process of Tenera Variety Fresh Fruit Bunches

    OpenAIRE

    Afshin Keshvadi; Johari Bin Endan, Haniff Harun, Desa Ahmad and Farah Saleena

    2011-01-01

    This research has done to determine of the relationship between palm oil development in mesocarp and kernel and Mechanical properties of fresh fruit bunches during the ripening process. For this purpose, Tenera oil palm (Elaeis guineensis) variety (A cross between Dura and Pisifera) on 8 year- old palms planted in 2003 at the Malaysian Palm Oil Board (MPOB) research station were selected. Fresh fruit bunches were harvested and were divided into three regions (Top, Middle and Bottom) where the...

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

    Science.gov (United States)

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

    2016-04-01

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

  2. Emittance growth due to static and radiative space charge forces in an electron bunch compressor

    CERN Document Server

    Talman, Richard; Stulle, Frank

    2009-01-01

    Evolution of short intense electron bunches passing through bunch-compressing beam lines is studied using the UAL (Unified Accelerator Libraries) string space charge formulation [R. Talman, Phys. Rev. ST Accel. Beams 7, 100701 (2004); N. Malitsky and R. Talman, in Proceedings of the 9th European Particle Accelerator Conference, Lucerne, 2004 (EPS-AG, Lucerne, 2004); R. Talman, Accelerator X-Ray Sources (Wiley-VCH, Weinheim, 2006), Chap. 13]. Three major configurations are studied, with the first most important and studied in greatest detail (because actual experimental results are available and the same results have been simulated with other codes): (i) Experimental bunch compression results were obtained at CTF-II, the CERN test facility for the “Compact Linear Collider” using electrons of about 40 MeV. Previous simulations of these results have been performed (using trafic4* [A. Kabel et al., Nucl. Instrum. Methods Phys. Res., Sect. A 455, 185 (2000)] and elegant [M. Borland, Argonne National Laboratory...

  3. On compensating tune spread induced by space charge in bunched beams

    Energy Technology Data Exchange (ETDEWEB)

    Litvinenko V. N.; Wang, G.

    2014-05-09

    Space charge effects play significant role in modern-day accelerators. These effects frequently constrain attainable beam parameters in an accelerator, or, in an accelerator chain. They also could limit the luminosity of hadron colliders operating either at low energies or with a sub-TeV high brightness hadron beams. The latter is applied for strongly cooled proton and ion beams in eRHIC – the proposed future electron-ion collider at Brookhaven National Laboratory. A number of schemes for compensating space charge effects in a coasting (e.g. continuous) hadron beam were proposed and some of them had been tested. Using a proper transverse profile of the electron beam (or plasma column) for a coasting beam would compensate both the tune shift and the tune spread in the hadron beam. But all of these methods do not address the issue of tune spread compensation of a bunched hadron beam, e.g. the tune shift dependence on the longitudinal position inside the bunch. In this paper we propose and evaluate a novel idea of using a co-propagating electron bunch with miss-matched longitudinal velocity to compensate the space charge induced tune-shift and tune spread. We present a number of practical examples of such system.

  4. Production of high intensity electron bunches for the SLAC Linear Collider

    International Nuclear Information System (INIS)

    This thesis describes the design and performance of a high intensity electron injecfor for the SLAC Linear Collider. Motivation for the collider and the specifications for the injector are discussed. An analytic theory of the bunching and capture of electrons by rf fields is discussed in the limit of low space charge and small signal. The design and performance of SLAC's main injector are described to illustrate a successful application of this theory. The bunching and capture of electrons by rf fields are then discussed in the limit of high space charge and large signal, and a description of the design of the collider injector follows. In the limit of high space charge forces and large rf signals, the beam dynamics are considerably more complex and numerical simulations are required to predict particle motion. A computer code which models the longitudinal dynamics of electrons in the presence of space charge and rf fields is described. The results of the simulations, the resulting collider injector design and the various components which make up the collider injector are described. These include the gun, subharmonic bunchers, traveling-wave buncher and velocity-of-light accelerator section. Finally, the performance of the injector is described including the beam intensity, bunch length, transverse emittance and energy spectrum. While the final operating conditions differ somewaht from the design, the performance of the collider injector is in good agreement with the numerical simulations and meets all of the collider specifications. 28 refs

  5. Analysis of the electron cloud observations with 25 ns bunch spacing at LHC

    CERN Document Server

    Iadarola, G; Rumolo, G; Arduini, G; Baglin, V; Banfi, D; Claudet, S; Dominguez, O; Esteban Müller, J; Pieloni, T; Shaposhnikova, E; Tavian, L; Zannini, C; Zimmermann, F

    2014-01-01

    Electron Cloud (EC) effects have been identified as a major performance limitation for the Large Hadron Collider (LHC) when operating with the nominal bunch spacing of 25 ns. During the LHC Run 1 (2010 - 2013) the luminosity production mainly used beams with 50 ns spacing, while 25 ns beams were only employed for short periods in 2011 and 2012 for test purposes. On these occasions, observables such as pressure rise, heat load in the cold sections as well as clear signatures on bunch-by-bunch emittance blow up, particle loss and energy loss indicated the presence of an EC in a large portion of the LHC. The analysis of the recorded data, together with EC build up simulations, has led to a significant improvement of our understanding of the EC effect in the different components of the LHC. Studies were carried out both at injection energy (450 GeV) and at top energy (4 TeV) aiming at determining the energy dependence of the EC formation and its impact on the quality of the proton beam.

  6. Production of high intensity electron bunches for the SLAC Linear Collider

    Energy Technology Data Exchange (ETDEWEB)

    James, M.B.

    1987-08-01

    This thesis describes the design and performance of a high intensity electron injecfor for the SLAC Linear Collider. Motivation for the collider and the specifications for the injector are discussed. An analytic theory of the bunching and capture of electrons by rf fields is discussed in the limit of low space charge and small signal. The design and performance of SLAC's main injector are described to illustrate a successful application of this theory. The bunching and capture of electrons by rf fields are then discussed in the limit of high space charge and large signal, and a description of the design of the collider injector follows. In the limit of high space charge forces and large rf signals, the beam dynamics are considerably more complex and numerical simulations are required to predict particle motion. A computer code which models the longitudinal dynamics of electrons in the presence of space charge and rf fields is described. The results of the simulations, the resulting collider injector design and the various components which make up the collider injector are described. These include the gun, subharmonic bunchers, traveling-wave buncher and velocity-of-light accelerator section. Finally, the performance of the injector is described including the beam intensity, bunch length, transverse emittance and energy spectrum. While the final operating conditions differ somewaht from the design, the performance of the collider injector is in good agreement with the numerical simulations and meets all of the collider specifications. 28 refs.

  7. Tunable High-Intensity Electron Bunch Train Production Based on Nonlinear Longitudinal Space Charge Oscillation

    Science.gov (United States)

    Zhang, Zhen; Yan, Lixin; Du, Yingchao; Zhou, Zheng; Su, Xiaolu; Zheng, Lianmin; Wang, Dong; Tian, Qili; Wang, Wei; Shi, Jiaru; Chen, Huaibi; Huang, Wenhui; Gai, Wei; Tang, Chuanxiang

    2016-05-01

    High-intensity trains of electron bunches with tunable picosecond spacing are produced and measured experimentally with the goal of generating terahertz (THz) radiation. By imposing an initial density modulation on a relativistic electron beam and controlling the charge density over the beam propagation, density spikes of several-hundred-ampere peak current in the temporal profile, which are several times higher than the initial amplitudes, have been observed for the first time. We also demonstrate that the periodic spacing of the bunch train can be varied continuously either by tuning launching phase of a radio-frequency gun or by tuning the compression of a downstream magnetic chicane. Narrow-band coherent THz radiation from the bunch train was also measured with μ J -level energies and tunable central frequency of the spectrum in the range of ˜0.5 to 1.6 THz. Our results pave the way towards generating mJ-level narrow-band coherent THz radiation and driving high-gradient wakefield-based acceleration.

  8. Tunable High-Intensity Electron Bunch Train Production Based on Nonlinear Longitudinal Space Charge Oscillation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhen; Yan, Lixin; Du, Yingchao; Zhou, Zheng; Su, Xiaolu; Zheng, Lianmin; Wang, Dong; Tian, Qili; Wang, Wei; Shi, Jiaru; Chen, Huaibi; Huang, Wenhui; Gai, Wei; Tang, Chuanxiang

    2016-05-05

    High-intensity trains of electron bunches with tunable picosecond spacing are produced and measured experimentally with the goal of generating terahertz (THz) radiation. By imposing an initial density modulation on a relativistic electron beam and controlling the charge density over the beam propagation, density spikes of several-hundred-ampere peak current in the temporal profile, which are several times higher than the initial amplitudes, have been observed for the first time. We also demonstrate that the periodic spacing of the bunch train can be varied continuously either by tuning launching phase of a radiofrequency gun or by tuning the compression of a downstream magnetic chicane. Narrow-band coherent THz radiation from the bunch train was also measured with μJ-level energies and tunable central frequency of the spectrum in the range of ~0.5 to 1.6 THz. Our results pave the way towards generating mJ-level narrow-band coherent THz radiation and driving high-gradient wakefield-based acceleration.

  9. Investigation of bunch repetition rate deviations in FIR FEL driven by a magnetron-based microtron

    CERN Document Server

    Kazakevitch, Grigori M; Lee Byung Cheol; Lee, J

    2002-01-01

    The stability of the bunch repetition rate in a FIR FEL driven by a 2.8 GHz magnetron-based microtron was investigated using a heterodyne method with a low Q-factor straight-flight measuring cavity. The measuring cavity is located in the straight section of the FIR FEL injection beam line and is excited by the passage of electron bunches. The RF signal from the measuring cavity coupling loop was mixed with a precise heterodyne signal with a frequency difference of several MHz. The beat frequency was analyzed to obtain the temporal distribution of the bunch repetition rate deviation during the macro pulse of the electron beam. The time resolution and the accuracy of measurements are approximately 100 ns and a few kHz, respectively. Based on this data, we could determine the level and shape of the magnetron current and the initial frequency shift between magnetron and accelerating cavity for the FEL operation in the wavelength range 100-300 microns.

  10. Bunch yield of interspecific hybrids of American oil palm with oil palm in the juvenile phase

    Directory of Open Access Journals (Sweden)

    Rui Alberto Gomes Junior

    2016-07-01

    Full Text Available To identify superior genotypes, 42 progenies of interspecific hybrids between American oil palm and oil palm were evaluated in an area with incidence of bud rot. The following variables were assessed: total bunch yield (TBY, number of bunches (NB and mean bunch weight (MBW from the third to the sixth year of cultivation and estimates of genetic parameters obtained by REML/BLUP procedures. High heritability values of the evaluated traits were observed. The gain estimates for TBY were 14.49% for the selection of the five best progenies and 33.36% for the selection of the five best trees, considering multiplication by cloning. A medium correlation was observed between TBY and NB (r2 = 0.33±0.021, a high correlation between TBY and MBW (r2 = 0.53±0.019 and a negative high correlation between NB and MBW (r2 = –0.60±0.018. The results indicate a high expectation of gains with selection for TBY.

  11. Stripline Transversal Filter Techniques for Sub-picosecond Bunch Timing Measurements

    International Nuclear Information System (INIS)

    Measurement of time of arrival of a particle bunch is a fundamental beam diagnostic. The PEP-II/ALS/BESSY/PLS longitudinal feedback systems use a planar stripline circuit to convert a 30 ps beam BPM impulse signal into a 4 cycle tone burst at the 6th harmonic of the accelerator RF frequency (2.856 GHz). A phase-detection technique is used to measure the arrival time of these BPM impulses with 200 fs rms single-shot resolution (out of a 330 ps dynamic range). Scaled in frequency, this approach is directly applicable to FEL and other sub-ps regime pulse and timing measurements. The transversal circuit structure is applicable to measurement of microbunches or closely spaced bunches (the PEP-II/ALS/BESSY/PLS examples make independent measurements at 2 ns bunch spacing) and opens up some new diagnostic and control possibilities. This paper reviews the principles of the technique, and uses data from PEP-II operations to predict the limits of performance of this measurement scheme for arrival phase measurement. These predictions are compared with results in the literature from electro-optic sub-picosecond beam timing and phasing diagnostics

  12. Demonstration of a real-time interferometer as a bunch-lenght monitor in a high-current electron beam accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Thangaraj, J.; Thurman-Keup, R.; Ruan, J.; Johnson, A.S.; Lumpkin, A; Santucci, J.; Maxwell, T.; /Fermilab; Andonian, G.; /UCLA /RadiaBeam Tech.; Murokh, A.; Ruelas, M.; Ovodenko, A.; /RadiaBeam Tech.

    2012-03-01

    A real-time interferometer (RTI) has been developed to monitor the bunch length of an electron beam in an accelerator. The RTI employs spatial autocorrelation, reflective optics, and a fast response pyro-detector array to obtain a real-time autocorrelation trace of the coherent radiation from an electron beam thus providing the possibility of online bunch-length diagnostics. A complete RTI system has been commissioned at the A0 photoinjector facility to measure sub-mm bunches at 13 MeV. Bunch length variation (FWHM) between 0.8 ps (-0.24 mm) and 1.5 ps (-0.45 mm) has been measured and compared with a Martin-Puplett interferometer and a streak camera. The comparisons show that RTI is a viable, complementary bunch length diagnostic for sub-mm electron bunches.

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

    Science.gov (United States)

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

    2016-06-01

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

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

    Directory of Open Access Journals (Sweden)

    Jifei Zhao

    2016-06-01

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

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

    Directory of Open Access Journals (Sweden)

    Mohamad A. Sukiran

    2009-01-01

    Full Text Available 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 different condition. Approach: In this study, pyrolysis of oil palm Empty Fruit Bunches (EFB was investigated using quartz fluidized fixed bed reactor. The effects of pyrolysis temperatures, particle sizes and heating rates on the yield of the products were investigated. The temperature of pyrolysis and heating rate were varied in the range 300-700 °C and 10-100 °C min1 respectively. The particle size was varied in the range of Results: Under the experimental conditions, the maximum bio-oil yield was 42.28% obtained at 500 ºC, with a heating rate of 100 ºC min-1 and particle size of 91-106 µm. The calorific values of bio-oil ranged from 20-21 MJ kg-1. A great range of functional groups of phenol, alcohols, ketones, aldehydes and carboxylic acids were indicated in FTIR spectrum. Conclusion: The chemical characterisation results showed that the bio-oil obtained from oil palm EFB maybe a potentially valuable source as fuel or chemical feedstocks.

  16. Long bunch trains measured using a prototype cavity beam position monitor for the Compact Linear Collider

    Science.gov (United States)

    Cullinan, F. J.; Boogert, S. T.; Farabolini, W.; Lefevre, T.; Lunin, A.; Lyapin, A.; Søby, L.; Towler, J.; Wendt, M.

    2015-11-01

    The Compact Linear Collider (CLIC) requires beam position monitors (BPMs) with 50 nm spatial resolution for alignment of the beam line elements in the main linac and beam delivery system. Furthermore, the BPMs must be able to make multiple independent measurements within a single 156 ns long bunch train. A prototype cavity BPM for CLIC has been manufactured and tested on the probe beam line at the 3rd CLIC Test Facility (CTF3) at CERN. The transverse beam position is determined from the electromagnetic resonant modes excited by the beam in the two cavities of the pickup, the position cavity and the reference cavity. The mode that is measured in each cavity resonates at 15 GHz and has a loaded quality factor that is below 200. Analytical expressions for the amplitude, phase and total energy of signals from long trains of bunches have been derived and the main conclusions are discussed. The results of the beam tests are presented. The variable gain of the receiver electronics has been characterized using beam excited signals and the form of the signals for different beam pulse lengths with the 2 /3 ns bunch spacing has been observed. The sensitivity of the reference cavity signal to charge and the horizontal position signal to beam offset have been measured and are compared with theoretical predictions based on laboratory measurements of the BPM pickup and the form of the resonant cavity modes as determined by numerical simulation. Finally, the BPM was calibrated so that the beam position jitter at the BPM location could be measured. It is expected that the beam jitter scales linearly with the beam size and so the results are compared to predicted values for the latter.

  17. High Charge PHIN Photo Injector at CERN with Fast Phase switching within the Bunch Train for Beam Combination

    CERN Document Server

    Csatari Divall, M; Bolzon, B; Bravin, E; Chevallay, E; Dabrowski, A; Doebert, S; Drozdy, A; Fedosseev, V; Hessler, C; Lefevre, T; Livesley, S; Losito, R; Olvegaard, M; Petrarca, M; Rabiller, A N; Egger, D; Mete, O

    2011-01-01

    The high charge PHIN photo-injector was developed within the framework of the European CARE program to provide an alternative to the drive beam thermionic gun in the CTF3 (CLIC Test Facility) at CERN. In PHIN 1908 electron bunches are delivered with bunch spacing of 1.5 GHz and 2.33 nC charge per bunch. Furthermore the drive beam generated by CTF3 requires several fast 180 deg phase-shifts with respect to the 1.5 GHz bunch repetition frequency in order to allow the beam combination scheme developed at CTF3. A total of 8 subtrains, each 140 ns long and shifted in phase with respect to each other, have to be produced with very high phase and amplitude stability. A novel fiber modulator based phase-switching technique developed on the laser system provides this phase-shift between two consecutive pulses much faster and cleaner than the base line scheme, where a thermionic electron gun and sub-harmonic bunching are used. The paper describes the fiber-based switching system and the measurements verifying the schem...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-02-11

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

  19. Study on energy difference compensation for high intense multi-bunch electron beam generated by a photocathode RF-gun

    International Nuclear Information System (INIS)

    At Waseda University, we have been studying a high quality electron beam generation and its application experiments with a Cs-Te photocathode RF-Gun. To generate more intense and stable electron beam, we have been developing the cathode irradiating UV laser which consists of optical fiber amplifier and LD pumped amplifier. As the result, more than 100 multi-bunch electron beam with 1nC each bunch charge was obtained. However, it has to be considered that the accelerating voltage will decrease because of the beam loading effect. So we have studied the RF amplitude modulation technique to compensate the bunch by bunch energy difference. The energy difference will caused by transient accelerating voltage in RF-Gun cavity and beam loading effect. As the result of this compensation method, the energy difference has been compensated to 1% p-p, while 5% p-p without compensation. In this conference, we will report our multi-bunch electron beam linac system, the details of energy compensation method using the RF amplitude modulation and the results of beam experiment. (author)

  20. Emission of Low-Energy Photons by Electrons at Electron-Positron and Electron-Ion Colliders with Dense Bunches

    CERN Document Server

    Jentschura, U D; Serbo, V G; 10.1103/PhysRevSTAB.12.011003

    2009-01-01

    Usually, the emission of low-energy photons in electron-positron (or electron-ion) bunch collisions is calculated with the same approach as for synchrotron radiation (beamstrahlung). However, for soft photons (E_gamma < E_c where E_c is a critical photon energy), when the coherence length of the radiation becomes comparable to the bunch length, the beamstrahlung approximation becomes invalid. In this paper, we present results of our calculation for this region based on approximation of classical currents. We consider several colliders with dense bunches. The number of low-energy photons dN_gamma emitted by N_e electrons per bunch crossing in the energy interval dE_gamma is dN_gamma = alpha g N_e dE_gamma/E_gamma, where alpha is the fine-structure constant, and the function g, which depends on the bunch parameters, typically is of order unity for modern colliders. In particular, for the ILC, we find that E_c = 83 keV and g=5.5 at a vanishing beam axis displacement, and g=0.88, E_c=0.24 keV for KEKB. We also...

  1. Electric field detection of coherent synchrotron radiation in a storage ring generated using laser bunch slicing

    Science.gov (United States)

    Katayama, I.; Shimosato, H.; Bito, M.; Furusawa, K.; Adachi, M.; Shimada, M.; Zen, H.; Kimura, S.; Yamamoto, N.; Hosaka, M.; Katoh, M.; Ashida, M.

    2012-03-01

    The electric field of coherent synchrotron radiation (CSR) generated by laser bunch slicing in a storage ring has been detected by an electro-optic sampling method. The gate pulses for sampling are sent through a large-mode-area photonic-crystal fiber. The observed electric field profile of the CSR is in good agreement with the spectrum of the CSR observed using Fourier transform far-infrared spectrometry, indicating good phase stability in the CSR. The longitudinal density profiles of electrons modulated by laser pulses were evaluated from the electric field profile.

  2. Dense Helical Electron Bunch Generation in Near-Critical Density Plasmas with Ultrarelativistic Laser Intensities

    OpenAIRE

    Ronghao Hu; Bin Liu; Haiyang Lu; Meilin Zhou; Chen Lin; Zhengming Sheng; Chia-erh Chen; Xiantu He; Xueqing Yan

    2015-01-01

    The mechanism for emergence of helical electron bunch(HEB) from an ultrarelativistic circularly polarized laser pulse propagating in near-critical density(NCD) plasma is investigated. Self-consistent three-dimensional(3D) Particle-in-Cell(PIC) simulations are performed to model all aspects of the laser plasma interaction including laser pulse evolution, electron and ion motions. At a laser intensity of 1022 W/cm2, the accelerated electrons have a broadband spectrum ranging from 300 MeV to 1.3...

  3. Method of controlling coherent synchroton radiation-driven degradation of beam quality during bunch length compression

    Science.gov (United States)

    Douglas, David R.; Tennant, Christopher D.

    2012-07-10

    A method of avoiding CSR induced beam quality defects in free electron laser operation by a) controlling the rate of compression and b) using a novel means of integrating the compression with the remainder of the transport system: both are accomplished by means of dispersion modulation. A large dispersion is created in the penultimate dipole magnet of the compression region leading to rapid compression; this large dispersion is demagnified and dispersion suppression performed in a final small dipole. As a result, the bunch is short for only a small angular extent of the transport, and the resulting CSR excitation is small.

  4. INDEPENDENT COMPONENT ANALYSIS (ICA) APPLIED TO LONG BUNCH BEAMS IN THE LOS ALAMOS PROTON STORAGE RING

    Energy Technology Data Exchange (ETDEWEB)

    Kolski, Jeffrey S. [Los Alamos National Laboratory; Macek, Robert J. [Los Alamos National Laboratory; McCrady, Rodney C. [Los Alamos National Laboratory; Pang, Xiaoying [Los Alamos National Laboratory

    2012-05-14

    Independent component analysis (ICA) is a powerful blind source separation (BSS) method. Compared to the typical BSS method, principal component analysis (PCA), which is the BSS foundation of the well known model independent analysis (MIA), ICA is more robust to noise, coupling, and nonlinearity. ICA of turn-by-turn beam position data has been used to measure the transverse betatron phase and amplitude functions, dispersion function, linear coupling, sextupole strength, and nonlinear beam dynamics. We apply ICA in a new way to slices along the bunch and discuss the source signals identified as betatron motion and longitudinal beam structure.

  5. Longitudinal Bunch Pattern Measurements through Single Photon Counting at SPEAR3

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hongyi (Jack); /UC, San Diego

    2012-09-07

    The Stanford Synchrotron Radiation Lightsource (SSRL), a division of SLAC National Accelerator Laboratory, is a synchrotron light source that provides x-rays for experimental use. As electrons are bent in the storage ring, they emit electromagnetic radiation. There are 372 different buckets which electrons can be loaded into. Different filling patterns produce different types of x-rays. What is the bunch pattern at a given time? Which filling pattern is better? Are there any flaws to the current injection system? These questions can be answered with this single photon counting experiment.

  6. Limitation of bunch compression in the ring due to the envelope instability and higher order modes

    International Nuclear Information System (INIS)

    In the SNS lattice at 70 MeV with four-fold bunch compression, the vertical tune is depressed from 1380 to 840. As part of the discussion concerning possible SNS/HIF simulation experiments, an investigation has been carried out of the threshold for the space-charge depressed tune below which a significant growth of the envelope may be expected, assuming that the tunes in x and y are different. The results indicate that compression by a factor of about 4 or more leads to the possibility of checking experimentally the theory of stability of periodic transport under strong space-charge conditions. (U.K.)

  7. Bunch-by-bunch beam loss monitor system in BEPCⅡ storage ring%BEPCⅡ储存环逐束团丢束监测系统及应用

    Institute of Scientific and Technical Information of China (English)

    邓庆勇; 曹建社; 岳军会; 魏源源; 麻惠洲; 杜垚垚

    2014-01-01

    A new prototype system for bunch-by-bunch beam position measurement has been designed and built to monitor and analyse the beam loss in the Beijing Electron-Positron ColliderⅡ(BEPCⅡ)storage ring.The fast ADC is used to sample the analog signals from the beam position monitor,then the digital signal is processed further using programmable gate array (FP-GA).The beam information can be obtained by means of bunch-by-bunch,such as bunch position,bunch current and bunch tune.Based on system monitoring and data analysis for long terms,as well as the dedicated machine experiments,it’s relatively clear for operators to understand some trip events,especially the beam loss caused by the high-frequency cavity trip,tune drift and multiple bunch instability.The study proves that the system is very useful for the operation of accelerator.%针对北京正负电子对撞机二期工程(BEPCⅡ)在高流强下运行经常出现的突然丢束问题,研制了基于逐束团测量的丢束监测系统。束流位置探头(BPM)的四路电极信号作为监测系统的信号源,四路高速模数转换器(ADC)和现场可编程门阵列(FPGA)进行模拟信号的数字化和数字信号的处理。通过获取丢束前每个束团的位置和流强等信息来分析引起丢束的原因。结合加速器硬件情况,长时间对丢束监测系统数据的分析,以及设计的对比实验,深入研究丢束问题。系统对高频系统故障、束流不稳定性和磁铁电源系统不稳定等原因引起的丢束现象可以做出准确的判断,进而为加速器稳定运行提供优化方向。

  8. Numerical Study of Injection Mechanisms for Generation of Mono-Energetic Femtosecond Electron Bunch from the Plasma Cathode

    CERN Document Server

    Ohkubo, Takeru; Zhidkov, Alexei

    2005-01-01

    Acceleration gradients of up to the order of 100GV/m and mono-energetic electron bunch up to 200MeV have recently been observed in several plasma cathode experiments. However, mechanisms of self-injection in plasma are not sufficiently clarified, presently. In this study, we carried out 2D PIC simulation to reveal the mechanisms of mono-energetic femtosecond electron bunch generation. We found two remarkable conditions for the generation: electron density gradient at vacuum-plasma interface and channel formation in plasma. Steep electron density gradient (~ plasma wave length) causes rapid injection and produces an electron bunch with rather high charge and less than 100fs duration. The channel formation guides an injected laser pulse and decreases the threshold of laser self-focusing, which leads to high electric field necessary for wave-breaking injection.

  9. Observation, control, and modal analysis of longitudinal coupled-bunch instabilities in the ALS via a digital feedback system

    International Nuclear Information System (INIS)

    The operation of a longitudinal multibunch damping system using digital signal processing (DSP) techniques is shown via measurements from the Lawrence Berkeley Laboratory (LBL) Advanced Light Source (ALS). The feedback system (developed for use by PEP-II, ALS, and DAΦNE) uses a parallel array of signal processors to implement a bunch-by-bunch feedback system for sampling rates up to 500 MHz. The programmable DSP system allows feedback control as well as accelerator diagnostics. A diagnostic technique is illustrated which uses the DSP system to excite and then damp the beam. The resulting 12-ms time domain transient is Fourier analyzed to provide the simultaneous measurement of growth rates and damping rates of all unstable coupled-bunch beam modes. copyright 1997 American Institute of Physics

  10. Spectral Decoding Electro Optic Bunch Length and Arrival Time Jitter Measurements at the DESY VUV-FEL

    CERN Document Server

    Steffen, Bernd; Knabbe, Ernst-Axel; 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 electrooptic spectral decoding (EOSD) experiment is installed to probe the time structure of the electric field of the bunches to better than 200 fs rms. The field induced birefringence of a ZnTe crystal is detected by TiSa laser pulses that are frequency chirped to ≈ 2 ps. The time structure is encoded on the wavelength spectrum of the chirped TiSa pulse. First results on the bunch length as function of the linac parameters and on time jitter measurements are presented.

  11. Transverse C-band deflecting structure for longitudinal electron-bunch-diagnosis in XFEL “SACLA”

    Energy Technology Data Exchange (ETDEWEB)

    Ego, H., E-mail: ego@spring8.or.jp [Japan Synchrotron Radiation Research Institute (JASRI), Kouto, Sayo, Hyogo (Japan); Maesaka, H.; Sakurai, T.; Otake, Y. [RIKEN SPring-8 Center, Kouto, Sayo, Hyogo (Japan); Hashirano, T.; Miura, S. [Mitsubishi Heavy Industries, Ltd. (MHI), Itozaki, Mihara, Hiroshima (Japan)

    2015-09-21

    In the 8 GeV compact X-ray FEL “SACLA,” a single bunch of electrons is compressed to a duration of approximately 30 fs to yield a peak current of 3 kA, which creates brilliant self-amplified spontaneous emission. To measure the longitudinal profile of an ultrashort electron bunch and verify the compression, we developed a high-gradient C-band RF deflecting structure 1.8 m long and periodically loaded with racetrack-shaped irises. The irises generated a high deflection gradient for the vertically deflecting HEM11-5π/6 dipole mode and suppressed rotation of the deflection plane. The two structures were fabricated and generated a stable total deflecting voltage exceeding 60 MV and revealed the longitudinal electron-bunch profile with an effective time resolution of approximately 10 fs.

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

    CERN Document Server

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

    2011-01-01

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

  13. A two-step method for retrieving the longitudinal profile of an electron bunch from its coherent radiation

    CERN Document Server

    Pelliccia, Daniele

    2014-01-01

    The coherent radiation emitted by an electron bunch provides a diagnostic signal that can be used to estimate its longitudinal distribution. Commonly only the amplitude of the intensity spectrum can be measured and the associated phase must be calculated to obtain the bunch profile. Very recently an iterative method was proposed to retrieve this phase. However ambiguities associated with non-uniqueness of the solution are always present in the phase retrieval procedure. Here we present a method to overcome the ambiguity problem by first performing multiple independent runs of the phase retrieval procedure and then second, sorting the good solutions by mean of cross-correlation analysis. Results obtained with simulated bunches of various shapes and experimental measured spectra are presented, discussed and compared with the established Kramers-Kronig method. It is shown that even when the effect of the ambiguities is strong, as is the case for a double peak in the profile, the cross-correlation post-processing...

  14. Excitation of Longitudinal Coupled-bunch Oscillations with the Wide-band Cavity in the CERN PS

    CERN Document Server

    Ventura, Letizia; Migliorati, Mauro; Sterbini, Guido

    2016-01-01

    Longitudinal coupled-bunch oscillations in the CERN Proton Synchrotron have been studied in the past years and they have been recognized as one of the major challenges to reach the high brightness beam required by the High Luminosity LHC project. In the frame of the LHC Injectors Upgrade project in 2014 a new wide-band Finemet cavity has been installed in the Proton Synchrotron as a part of the coupled-bunch feedback system. To explore the functionality of the Finemet cavity during 2015 a dedicated measurement campaign has been performed. Coupled-bunch oscillations have been excited with the cavity around each harmonic of the revolution frequency with both a uniform and nominal filling pattern. In the following the measurements procedure and results are presented.

  15. Screening and incorporation of rust resistance from Allium cepa into bunching onion (Allium fistulosum) via alien chromosome addition.

    Science.gov (United States)

    Wako, Tadayuki; Yamashita, Ken-ichiro; Tsukazaki, Hikaru; Ohara, Takayoshi; Kojima, Akio; Yaguchi, Shigenori; Shimazaki, Satoshi; Midorikawa, Naoko; Sakai, Takako; Yamauchi, Naoki; Shigyo, Masayoshi

    2015-04-01

    Bunching onion (Allium fistulosum L.; 2n = 16), bulb onion (Allium cepa L. Common onion group), and shallot (Allium cepa L. Aggregatum group) cultivars were inoculated with rust fungus, Puccinia allii, isolated from bunching onion. Bulb onions and shallots are highly resistant to rust, suggesting they would serve as useful resources for breeding rust resistant bunching onions. To identify the A. cepa chromosome(s) related to rust resistance, a complete set of eight A. fistulosum - shallot monosomic alien addition lines (MAALs) were inoculated with P. allii. At the seedling stage, FF+1A showed a high level of resistance in controlled-environment experiments, suggesting that the genes related to rust resistance could be located on shallot chromosome 1A. While MAAL, multi-chromosome addition line, and hypoallotriploid adult plants did not exhibit strong resistance to rust. In contrast to the high resistance of shallot, the addition line FF+1A+5A showed reproducibly high levels of rust resistance.

  16. Multi-chromatic narrow-energy-spread electron bunches from laser wakefield acceleration with dual color lasers

    CERN Document Server

    Zeng, Ming; Yu, Lu-Le; Mori, Warren B; Sheng, Zheng-Ming; Hidding, Bernhard; Jaroszynski, Dino; Zhang, Jie

    2014-01-01

    A method based on laser wakefield acceleration is proposed that can generate electron bunches with an energy spectrum containing multiple spikes each with very narrow energy spread. The method is demonstrated through multi-dimensional particle-in-cell simulations. The beating of bichromatic short pulse laser fields allows controlled ionization injection of electrons into an accelerating bucket. Due to the different dispersion of the two color pulses co-propagating in the background plasma, the peak amplitude of the combined laser field oscillates during the propagation. Ionization injection occurs when the peak amplitude exceeds an ionization threshold. The threshold is exceeded for limited durations at different propagation distances. Electrons from each injection duration produce separate electron bunches. This combined with an oscillating bubble in multi-dimensions produces an energy spectrum with multi-chromatic spikes, where each spike has an energy spread less than 1%. Such electron bunches could be use...

  17. X-Band deflecting cavity design for ultra-short bunch length measurement of SXFEL at SINAP

    CERN Document Server

    Tan, Jian-Hao; Fang, Wen-Cheng; Tong, De-Chun; Zhao, Zhen-Tang

    2014-01-01

    For the development of the X-ray Free Electron Lasers test facility (SXFEL) at SINAP, ultra-short bunch is the crucial requirement for excellent lasing performance. It's a big challenge for deflecting cavity to measure the length of ultra-short bunch, and higher deflecting gradient is required for higher measurement resolution. X-band travelling wave deflecting structure has features of higher deflecting voltage and compact structure, which is good performance at ultra-short bunch length measurement. In this paper, a new X-band deflecting structure has been designed operated at HEM11-2pi/3 mode. For suppressing the polarization of deflecting plane of the HEM11 mode, two symmetrical caves are added on the cavity wall to separate two polarized modes. More details of design and simulation results are presented in this paper.

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

    International Nuclear Information System (INIS)

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

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

    International Nuclear Information System (INIS)

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

  20. Reflective optical system for time-resolved electron bunch measurements at PITZ

    Energy Technology Data Exchange (ETDEWEB)

    Rosbach, K.; Baehr, J. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Roensch-Schulenburg, J. [Hamburg Univ. (Germany). Inst. fuer Experimentalphysik

    2011-01-15

    The Photo-Injector Test facility at DESY, Zeuthen site (PITZ), produces pulsed electron beams with low transverse emittance and is equipped with diagnostic devices for measuring various electron bunch properties, including the longitudinal and transverse electron phase space distributions. The longitudinal bunch structure is recorded using a streak camera located outside the accelerator tunnel, connected to the diagnostics in the beam-line stations by an optical system of about 30 m length. This system mainly consists of telescopes of achromatic lenses, which transport the light pulses and image them onto the entrance slit of the streak camera. Due to dispersion in the lenses, the temporal resolution degrades during transport. This article presents general considerations for time-resolving optical systems as well as simulations and measurements of specific candidate systems. It then describes the development of an imaging system based on mirror telescopes which will improve the temporal resolution, with an emphasis on off-axis parabolic mirror systems working at unit magnification. A hybrid system of lenses and mirrors will serve as a proof of principle. (orig.)

  1. Measurement of Schottky-like Signals from Linac Bunched Hadron Beams for Momentum Spread Evaluation

    CERN Document Server

    Kowina, P; Caspers, F; Singh, R

    2013-01-01

    We present a novel method for the measurement of Linac beam parameters in the longitudinal phase space. The longitudinal momentum spread can be evaluated by means of Schottky type signal analysis of bunched beams. There is a close similarity between a repetitive Linac bunch train and a circulating beam with a single short batch in a large machine like the LHC. A dedicated longitudinal cavity pick-up was used in the Linac where resonance frequency and Q-value were carefully selected in order to get an optimum compromise between the unavoidable coherent signal and the desired incoherent part of the beam spectrum. A time domain gating similar to the 4.8 GHz LHC Schottky front-end is applied. As a cross-check of the validity of the interpretation in terms of momentum spread, the Linac beam is analyzed in the downstream synchrotron using standard Schottky methods. In principle, this approach can be understood as an extension of Schottky analysis for circular machines with a perfect “mixing” between subsequent ...

  2. Bio-composite Nonwoven Media Based on Chitosan and Empty Fruit Bunches for Wastewater Application

    International Nuclear Information System (INIS)

    Fibrous filter media in the form of non-woven filters have been used extensively in water treatment as pre-filters or to support the medium that does the separation. Lignocellulosic such as empty fruit bunches have potential to be used as a low cost filter media as they represent unused resources, widely available and are environmentally friendly. Laboratory filtration tests were performed to investigate the potential application of empty fruit bunches that enriched with chitosan as a fiber filter media to remove suspended solids, oil and grease, and organics in terms of chemical oxygen demand from palm oil mill effluent. The present paper studies the effect of chitosan concentration on the filter media performance. Bench-scaled experiment results indicated that pre-treatment using the fiber filtration system removed up to 67.3% of total suspended solid, 65.1% of oil and grease and 46.1% of chemical oxygen demand. The results show that the lignocellulosic fiber filter could be a potential technology for primary wastewater treatment.

  3. Bio-composite Nonwoven Media Based on Chitosan and Empty Fruit Bunches for Wastewater Application

    Science.gov (United States)

    Sadikin, Aziatul Niza; Nawawi, Mohd Ghazali Mohd; Othman, Norasikin

    2011-01-01

    Fibrous filter media in the form of non-woven filters have been used extensively in water treatment as pre-filters or to support the medium that does the separation. Lignocellulosic such as empty fruit bunches have potential to be used as a low cost filter media as they represent unused resources, widely available and are environmentally friendly. Laboratory filtration tests were performed to investigate the potential application of empty fruit bunches that enriched with chitosan as a fiber filter media to remove suspended solids, oil and grease, and organics in terms of chemical oxygen demand from palm oil mill effluent. The present paper studies the effect of chitosan concentration on the filter media performance. Bench-scaled experiment results indicated that pre-treatment using the fiber filtration system removed up to 67.3% of total suspended solid, 65.1% of oil and grease and 46.1% of chemical oxygen demand. The results show that the lignocellulosic fiber filter could be a potential technology for primary wastewater treatment.

  4. On the Production of Flat Electron Bunches for Laser Wake Field Acceleration

    Energy Technology Data Exchange (ETDEWEB)

    Kando, M.; Fukuda, Y.; Kotaki, H.; Koga, J.; Bulanov, S.V.; Tajima, T.; /JAERI, Kyoto; Chao, A.; Pitthan, R.; /SLAC; Schuler, K.-P.; /DESY; Zhidkov, A.G.; /CRIEPI, Tokyo; Nemoto, K.; /CRIEPI, Tokyo

    2006-06-27

    We suggest a novel method for injection of electrons into the acceleration phase of particle accelerators, producing low emittance beams appropriate even for the demanding high energy Linear Collider specifications. In this paper we work out the injection into the acceleration phase of the wake field in a plasma behind a high intensity laser pulse, taking advantage of the laser polarization and focusing. With the aid of catastrophe theory we categorize the injection dynamics. The scheme uses the structurally stable regime of transverse wake wave breaking, when electron trajectory self-intersection leads to the formation of a flat electron bunch. As shown in three-dimensional particle-in-cell simulations of the interaction of a laser pulse in a line-focus with an underdense plasma, the electrons, injected via the transverse wake wave breaking and accelerated by the wake wave, perform betatron oscillations with different amplitudes and frequencies along the two transverse coordinates. The polarization and focusing geometry lead to a way to produce relativistic electron bunches with asymmetric emittance (flat beam). An approach for generating flat laser accelerated ion beams is briefly discussed.

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

    Directory of Open Access Journals (Sweden)

    Wan Rosli Wan Daud

    2007-01-01

    Full Text Available 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. They had numerous silica-bodies attached to craters on their surfaces; the craters were perforated at the bottom. Many other minerals were also present in the strands. Our microscopic observations suggested that the silica-bodies are connected to a network of siliceous pathway within the fibrous matrix, and minerals tend to concentrate adjacent to the silica-bodies. Our findings could be useful in identifying suitable techniques for processing the oil palm fiber strands into value-added products.

  6. Hydrothermal pre-treatment of oil palm empty fruit bunch into fermentable sugars

    Science.gov (United States)

    Muhd Ali, M. D.; Tamunaidu, P.; Nor Aslan, A. K. H.; Morad, N. A.; Sugiura, N.; Goto, M.; Zhang, Z.

    2016-06-01

    Presently oil palm empty fruit bunch (OPEFB) is one of the solid waste which is produced daily whereby it is usually left at plantation site to act as organic fertilizer for the plants to ensure the sustainability of fresh fruit bunch. The major drawback in biomass conversion technology is the difficulty of degrading the material in a short period of time. A pre-treatment step is required to break the lignocellulosic biomass to easily accessible carbon sources for further use in the production of fuels and fine chemicals. Therefore, this study investigated the effect of hydrothermal pre-treatment under different reaction temperatures (100 - 250°C), reaction time (10 - 40 min), solid to solvent ratio of (1:10 - 1:20 w/v) and particle size (0.15 - 1.00 mm) on the solubilization of OPEFB to produce soluble fermentable sugars. The maximum soluble sugars of 68.18 mg glucose per gram of OPEFB were achieved at 175°C of reaction temperature, 20 min of reaction time, 1:15 w/v of solid to solvent ratio for 30 mm of particle size. Results suggest that reaction temperature, reaction time, the amount of solid to solvent ratio and size of the particle are crucial parameters for hydrothermal pretreatment, in achieving a high yield of soluble fermentable sugars.

  7. Matching the laser generated p bunch into a crossbar-H drift tube linac

    Science.gov (United States)

    Almomani, A.; Droba, M.; Ratzinger, U.; Hofmann, I.

    2012-05-01

    Proton bunches with energies up to 30 MeV have been measured at the PHELIX laser. Because of the laser-plasma interactions at a power density of about 4×1019W/cm2, a total yield of 1.5×1013protons was produced. For the reference energy of 10 MeV, the yield within ±0.5MeV was exceeding 1010protons. The important topic for a further acceleration of the laser generated bunch is the matching into the acceptance of an rf accelerator stage. With respect to the high space charge forces and the transit energy range, only drift tube linacs seem adequate for this purpose. A crossbar H-type (CH) cavity was chosen as the linac structure. Optimum emittance values for the linac injection are compared with the available laser generated beam parameters. Options for beam matching into a CH structure by a pulsed magnetic solenoid and by using the simulation codes LASIN and LORASR are presented.

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

    Directory of Open Access Journals (Sweden)

    Mohamad A. Sukiran

    2011-01-01

    Full Text Available Problem statement: The palm oil industry generates an abundance of oil palm biomass such as the Empty Fruit Bunch (EFB, shell, frond, trunk and Palm Oil Mill Effluent (POME. For 88 million tones of Fresh Fruit Bunch (FFB processed in 2008, the amount of oil palm biomass was more than 26 million tones. Studies about production of bio-char from oil palm biomass are still lacking in Malaysia. So, this study was aimed to: (i determine the effect of pyrolysis temperatures on bio-char yield (ii characterize the bio-char obtained under different pyrolysed temperatures. Approach: In this study, pyrolysis of EFB was conducted using a fluidized fixed bed reactor. The effect of pyrolysis temperatures on bio-char yield was investigated. The pyrolysis temperature used ranged from 300-700°C. The elemental analysis, calorific value, surface area and total pore volume of the bio-char were determined. Results: The highest bio char yield of 41.56% was obtained at an optimum pyrolysis temperature of 300°C with particle size of 91-106 μm and the heating rate of 30°C min-1. The calorific values of bio-char ranged from 23-26 MJ kg-1. Conclusion: It was found that the bio-char products can be characterized as carbon rich, high calorific value and potential solid biofuels.

  9. Reflective optical system for time-resolved electron bunch measurements at PITZ

    International Nuclear Information System (INIS)

    The Photo-Injector Test facility at DESY, Zeuthen site (PITZ), produces pulsed electron beams with low transverse emittance and is equipped with diagnostic devices for measuring various electron bunch properties, including the longitudinal and transverse electron phase space distributions. The longitudinal bunch structure is recorded using a streak camera located outside the accelerator tunnel, connected to the diagnostics in the beam-line stations by an optical system of about 30 m length. This system mainly consists of telescopes of achromatic lenses, which transport the light pulses and image them onto the entrance slit of the streak camera. Due to dispersion in the lenses, the temporal resolution degrades during transport. This article presents general considerations for time-resolving optical systems as well as simulations and measurements of specific candidate systems. It then describes the development of an imaging system based on mirror telescopes which will improve the temporal resolution, with an emphasis on off-axis parabolic mirror systems working at unit magnification. A hybrid system of lenses and mirrors will serve as a proof of principle. (orig.)

  10. Development of deflector cavity and RF amplifier for bunch length detector system

    Science.gov (United States)

    Pandey, H. K.; Bhattacharya, T. K.; Chakrabarti, A.

    2016-02-01

    A minimally-interceptive bunch length detector system is being developed for measurement of longitudinal dimension of the bunch beam from RFQ of the radioactive ion beam (RIB) facility at VECC. This detector system is based on secondary electrons emission produced by the primary ion beam hitting a thin tungsten wire placed in the beam path. In this paper we report the design, development and off line testing results of deflector cavity together with its RF sysytem. The deflector cavity is a capacitive loaded helical type λ/2 resonator driven by RF source of 500 W at 37.8 MHz solid state amplifier, realized by combining two amplifier modules of 300 W each. The measured RF characteristics of the resonator, such as frequency, Q value and shunt impedance have been found to be reasonably good and close to the analytical estimation and results of simulation. The design philosophy and test results of individual components of the amplifier are discussed. The test result upto full power shows a good harmonic separation at the individual module level and this is found to improve further when modules are combined together.The results of high power performance test of the deflector cavity together with amplifier are also reported.

  11. A Bunch Compression Method for Free Electron Lasers that Avoids Parasitic Compressions

    Energy Technology Data Exchange (ETDEWEB)

    Benson, Stephen V. [Jefferson Lab, Newport News, VA; Douglas, David R. [Jefferson Lab, Newport News, VA; Tennant, Christopher D. [Jefferson Lab, Newport News, VA; Wilson, Frederick G. [Jefferson Lab, Newport News, VA; Nguyen, Dinh [Brookhaven National Lab, Upton, NY

    2015-09-01

    Virtually all existing high energy (>few MeV) linac-driven FELs compress the electron bunch length though the use of off-crest acceleration on the rising side of the RF waveform followed by transport through a magnetic chicane. This approach has at least three flaws: 1) it is difficult to correct aberrations--particularly RF curvature, 2) rising side acceleration exacerbates space charge-induced distortion of the longitudinal phase space, and 3) all achromatic "negative compaction" compressors create parasitic compression during the final compression process, increasing the CSR-induced emittance growth. One can avoid these deficiencies by using acceleration on the falling side of the RF waveform and a compressor with M56>0. This approach offers multiple advantages: 1) It is readily achieved in beam lines supporting simple schemes for aberration compensation, 2) Longitudinal space charge (LSC)-induced phase space distortion tends, on the falling side of the RF waveform, to enhance the chirp, and 3) Compressors with M56>0 can be configured to avoid spurious over-compression. We will discuss this bunch compression scheme in detail and give results of a successful beam test in April 2012 using the JLab UV Demo FEL

  12. Physicochemical profile of microbial-assisted composting on empty fruit bunches of oil palm trees.

    Science.gov (United States)

    Lim, Li Yee; Bong, Cassendra Phun Chien; Chua, Lee Suan; Lee, Chew Tin

    2015-12-01

    This study was carried out to investigate the physicochemical properties of compost from oil palm empty fruit bunches (EFB) inoculated with effective microorganisms (EM∙1™). The duration of microbial-assisted composting was shorter (∼7 days) than control samples (2 months) in a laboratory scale (2 kg) experiment. The temperature profile of EFB compost fluctuated between 26 and 52 °C without the presence of consistent thermophilic phase. The pH of compost changed from weak acidic (pH ∼5) to mild alkaline (pH ∼8) because of the formation of nitrogenous ions such as ammonium (NH4 (+)), nitrite (NO2 (-)), and nitrate (NO3 (-)) from organic substances during mineralization. The pH of the microbial-treated compost was less than 8.5 which is important to prevent the loss of nitrogen as ammonia gas in a strong alkaline condition. Similarly, carbon mineralization could be determined by measuring CO2 emission. The microbial-treated compost could maintain longer period (∼13 days) of high CO2 emission resulted from high microbial activity and reached the threshold value (120 mg CO2-C kg(-1) day(-1)) for compost maturity earlier (7 days). Microbial-treated compost slightly improved the content of minerals such as Mg, K, Ca, and B, as well as key metabolite, 5-aminolevulinic acid for plant growth at the maturity stage of compost. Graphical Abstract Microbial-assisted composting on empty fruit bunches.

  13. Selective component degradation of oil palm empty fruit bunches (OPEFB) using high-pressure steam

    International Nuclear Information System (INIS)

    In order to accelerate the bioconversion process of press-shredded empty fruit bunches (EFB), the effect of high-pressure steam pre-treatment (HPST) in degrading the lignocellulosic structure was investigated. HPST was carried out under various sets of temperature/pressure conditions such as 170/0.82, 190/1.32, 210/2.03, and 230 °C/3.00 MPa. It was noted that after HPST, the surface texture, color, and mechanical properties of the treated EFB had obviously altered. Scanning electron micrographs of the treated EFB exhibited effective surface erosion that had occurred along the structure. Moreover, the Fourier transform infrared and thermogravimetric analyses showed the removal of silica bodies and hemicellulose ingredients. X-ray diffraction profiles of the treated EFB indicated significant increases in crystallinity. These results reveal that HPST is an effective pre-treatment method for altering the physicochemical properties of the EFB and enhancing its biodegradability characteristics for the bioconversion process. -- Highlights: ► Bioconversion of empty fruit bunches (EFB) was accelerated by high-pressure steam pre-treatment. ► Scanning electron micrographs exhibited surface erosion as well as composting over 20 days. ► FT-IR and TG data showed the selective removal of silica bodies and hemicellulose ingredient. ► X-ray diffraction profiles of the treated EFB indicated significant increases in crystallinity

  14. Effect of nonlinear radiofrequency electromagnetic fields on the emittance of bunched beams

    Science.gov (United States)

    Phadte, D. S.; Patidar, C. B.

    2013-07-01

    Gap transformations are frequently used in ion Linac codes, to efficiently describe the particle dynamics. Using similar approach, we analyze the uniformly bunched beam passing through an axis-symmetric radiofrequency (RF) cavity. The method can be used for other distributions as well using a similar six dimensional analysis. The effect of non-linear RF field in radial and axial directions in an RF cavity and the finite phase width of the bunch, on the transverse and longitudinal emittance growth have been studied. The expressions obtained have been verified for the two types of cavity cells namely the zero mode DTL and pi mode CCL type used frequently in ion linacs. The results are seen to be valid for the entire maximum phase acceptance up to 360 degrees. Simulations with the equivalent beams of non-uniform distributions namely Waterbag and Gaussian show that at synchronous phases closer to the wave crest, the results give a good approximation of emittance growth in both planes for non-uniform beams.

  15. Ion bunch stacking in a Penning trap after purification in an electrostatic mirror trap

    CERN Document Server

    Rosenbusch, M; Blaum, K; Borgmann, Ch; Kreim, S; Lunney, D; Manea, V; Schweikhard, L; Wienholtz, F; Wolf, R N

    2014-01-01

    The success of many measurements in analytical mass spectrometry as well as in precision mass determinations for atomic and nuclear physics is handicapped when the ion sources deliver ``contaminations'', i.e., unwanted ions of masses similar to those of the ions of interest. In particular, in ion-trapping devices, large amounts of contaminant ions result in significant systematic errors-if the measurements are possible at all. We present a solution for such cases: The ions from a quasi-continuous source are bunched in a linear radio-frequency-quadrupole ion trap, separated by a multi-reflection time-of-flight section followed by a Bradbury-Nielsen gate, and then captured in a Penning trap. Buffer-gas cooling is used to damp the ion motion in the latter, which allows a repeated opening of the Penning trap for a stacking of mass-selected ion bunches. Proof-of-principle demonstrations have been performed with the ISOLTRAP setup at ISOLDE/CERN, both with Cs-133(+) ions from an off-line ion source and by applicati...

  16. The Bunch Injection Controller for the PEP-II Storage Rings

    CERN Document Server

    Chestnut, R

    2001-01-01

    The PEP-II storage rings at SLAC each have 3492 'buckets' into which electrons and positrons can be injected into the high- and low-energy rings. Equipment to measure the currents of all the individual buckets was originally provided by the Lawrence Berkeley Laboratory and is implemented in VXI-based hardware. Data from this equipment as well as high precision direct current measurement provide the hard data for the Bunch Injection Controller. A large number of parameters determined by injection design considerations as well as set by operators for different circumstances are also used by the software algorithms to determine the desired bucket injection order and charge quantity for each injection pulse. These requests are then passed on to the venerable SLAC master pattern generator, which provides beams for other applications as well. This highly visible and highly successful system is implemented using the EPICS toolkit, and fits well into the merged SLAC EPICS/SLC control system. The Bunch Injection Contr...

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

    Energy Technology Data Exchange (ETDEWEB)

    Berg, J.S.

    1996-03-01

    A method is presented for determining the stability of a system consisting of several highly relativistic bunches of charged particles circulating in a storage ring. The particles interact with magnets designed to guide the beam as well as with electromagnetic fields induced by the particles themselves. Previous work has considered modes where all bunches in the ring are executing the same type of internal oscillation. This dissertation considers the results of allowing those modes to couple to one another. The formalism begins with a self-consistent distribution, and analyzes small perturbations to that distribution to determine if they grow exponentially. The formalism allows one to do this computation for an arbitrary magnetic lattice, as well as an arbitrary distribution of wakefield sources around the ring. The method also allows for the inclusion of a feedback system which is designed to damp multibunch oscillations. The PEP-II B-factory with a linear lattice is used as an example to demonstrate and explain the phenomenology that results from this coupling of multibunch modes. The effect of adding feedback is also explored.

  18. Gasification of bio char from empty fruit bunch in a fluidized bed

    International Nuclear Information System (INIS)

    Full text: Bio char from empty fruit bunch was gasified in a fluidized bed reactor using compressed air as a gasifying agent. The experiment was conducted in the temperature ranges of 500-850 degree Celsius and the equivalence ratio, temperature and size of the feedstock was varied. A series of parameters such as gas yield, overall carbon conversion, gas quality, and composition, were measured as a function of temperature, equivalence ratio and temperature. Results obtained were compared to the actual values of coal and other gasification feedstock reveal that, bio char has the potential to replace coal as a gasification agent in power plants .Hydrogen gas from bio char was also optimized during the experiment. There is great potential of making Hydrogen from Bio char through thermo chemical gasification It was observed that it has a very great potential of being upgraded to Fischer Tropsh fuels. There is a great opportunity of using this char from empty fruit bunch as an alternative fuel in power plants and all the adverse effects of coal gasification can be counteracted. (author)

  19. Suppression of Beam-Ion Instability in Electron Rings with Multi-Bunch Train Beam Fillings

    Energy Technology Data Exchange (ETDEWEB)

    Wang, L.; Cai, Y.; Raubenheimer, T.O.; /SLAC; Fukuma, H.; /KEK, Tsukuba

    2011-08-18

    The ion-caused beam instability in the future light sources and electron damping rings can be serious due to the high beam current and ultra-small emittance of picometer level. One simple and effective mitigation of the instability is a multi-bunch train beam filling pattern which can significantly reduce the ion density near the beam, and therefore reduce the instability growth rate up to two orders of magnitude. The suppression is more effective for high intensity beams with low emittance. The distribution and the field of trapped ions are benchmarked to validate the model used in the paper. The wake field of ion-cloud and the beam-ion instability is investigated both analytically and numerically. We derived a simple formula for the build-up of ion-cloud and instability growth rate with the multi-bunch-train filling pattern. The ion instabilities in ILC damping ring, SuperKEKB and SPEAR3 are used to compare with our analyses. The analyses in this paper agree well with simulations.

  20. Splittings, coalescence, bunch and snake patterns in the 3D nonlinear Schrödinger equation with anisotropic dispersion

    DEFF Research Database (Denmark)

    Germaschewski, K.; Grauer, R.; Bergé, L.;

    2001-01-01

    are detailed and compared with those characterizing collapsing objects with no anisotropic dispersion. Their ability to mutually coalesce is also analyzed and modeled from the interaction of Gaussian components. Next, bunch-type and snake-type instabilities, which result from periodic modulations driven...... by even and odd localized modes, are studied. The influence of the initial wave amplitude, the amplitude and wavenumber of the perturbations on the interplay of snake and bunch patterns are finally discussed. (C) 2001 Elsevier Science B.V. All rights reserved....

  1. Hydrolysis of Oil Palm Empty Fruit Bunch Fibers to Produce Sugar Hydrolyzate as Raw Material for Bioethanol Production

    OpenAIRE

    Fitriani Kasim; Anwar Kasim

    2013-01-01

    A study conducted to see the effect of the regulation and control of temperature on the length of the hydrolysis of oil palm empty fruit bunches fiber and the resulting hydrolyzate sugar levels, which will be planned to be used as raw material for bioethanol. Therefore do oil palm empty fruit bunches fiber hydrolysis with sulfuric acid (H2SO4) at low concentrations (1%) using an autoclave with a temperature of 120 ° C and 130 ° C, and the time for 30, 60, 90, 120 minutes. After that the obser...

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

    OpenAIRE

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

    2008-01-01

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

  3. Electron diffraction using ultrafast electron bunches from a laser-wakefield accelerator at kHz repetition rate

    OpenAIRE

    He, Z.-H; Thomas, A. G. R.; Beaurepaire, B; Nees, J. A.; Hou, B.; Malka, Victor; Krushelnick, K; Faure, Jérôme

    2013-01-01

    We show that electron bunches in the 50-100 keV range can be produced from a laser wake-field accelerator using 10 mJ, 35 fs laser pulses operating at 0.5 kHz. It is shown that using a solenoid magnetic lens, the electron bunch distribution can be shaped. The resulting transverse and longitudinal coherence is suitable for producing diffraction images from a polycrystalline 10 nm aluminum foil. The high repetition rate, the stability of the electron source and the fact that its uncorrelated bu...

  4. Controlled electron bunch generation in the few-cycle ultra-intense laser-solid interaction scenario

    Science.gov (United States)

    Kluge, T.; Bussmann, M.; Cowan, T. E.; Schramm, U.

    2016-09-01

    The generation of Maxwellian or exponentially decaying spectra in the interaction of ultra-intense ultra-short laser pulses with solid foils is very general observation both in experiments and simulations. Yet, the physical origin of this observation is not well understood. For a very idealized situation of plane wave, plane and cold target interaction, we show that both randomization between individual electron bunches accelerated by the laser through the plasma as well as randomization during a single bunch are not observable in particle-in-cell simulations. Hence they are not accountable for the apparent thermalization (exponential spectrum).

  5. Observation of coherently enhanced tunable narrow-band terahertz transition radiation from a relativistic sub-picosecond electron bunch train

    Energy Technology Data Exchange (ETDEWEB)

    Piot, P. [Northern Illinois Univ., DeKalb, IL (United States); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Sun, Y. -E [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Maxwell, T. J. [Northern Illinois Univ., DeKalb, IL (United States); Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Ruan, J. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Lumpkin, A. H. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Rihaoui, M. M. [Northern Illinois Univ., DeKalb, IL (United States); Thurman-Keup, R. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)

    2011-06-27

    We experimentally demonstrate the production of narrow-band (δf/f ~ =20% at f ~ = 0.5 THz) THz transition radiation with tunable frequency over [0.37, 0.86] THz. The radiation is produced as a train of sub-picosecond relativistic electron bunches transits at the vacuum-aluminum interface of an aluminum converter screen. In addition, we show a possible application of modulated beams to extend the dynamical range of a popular bunch length diagnostic technique based on the spectral analysis of coherent radiation.

  6. Method for maximizing the brightness of the bunches in a particle injector by converting a highly space-charged beam to a relativistic and emittance-dominated beam

    Energy Technology Data Exchange (ETDEWEB)

    Hannon, Fay

    2016-08-02

    A method for maximizing the brightness of the bunches in a particle injector by converting a highly space-charged beam to a relativistic and emittance-dominated beam. The method includes 1) determining the bunch charge and the initial kinetic energy of the highly space-charge dominated input beam; 2) applying the bunch charge and initial kinetic energy properties of the highly space-charge dominated input beam to determine the number of accelerator cavities required to accelerate the bunches to relativistic speed; 3) providing the required number of accelerator cavities; and 4) setting the gradient of the radio frequency (RF) cavities; and 5) operating the phase of the accelerator cavities between -90 and zero degrees of the sinusoid of phase to simultaneously accelerate and bunch the charged particles to maximize brightness, and until the beam is relativistic and emittance-dominated.

  7. Time domain numerical calculations of the short electron bunch wakefields in resistive structures

    Energy Technology Data Exchange (ETDEWEB)

    Tsakanian, Andranik

    2010-10-15

    The acceleration of electron bunches with very small longitudinal and transverse phase space volume is one of the most actual challenges for the future International Linear Collider and high brightness X-Ray Free Electron Lasers. The exact knowledge on the wake fields generated by the ultra-short electron bunches during its interaction with surrounding structures is a very important issue to prevent the beam quality degradation and to optimize the facility performance. The high accuracy time domain numerical calculations play the decisive role in correct evaluation of the wake fields in advanced accelerators. The thesis is devoted to the development of a new longitudinally dispersion-free 3D hybrid numerical scheme in time domain for wake field calculation of ultra short bunches in structures with walls of finite conductivity. The basic approaches used in the thesis to solve the problem are the following. For materials with high but finite conductivity the model of the plane wave reflection from a conducting half-space is used. It is shown that in the conductive half-space the field components perpendicular to the interface can be neglected. The electric tangential component on the surface contributes to the tangential magnetic field in the lossless area just before the boundary layer. For high conducting media, the task is reduced to 1D electromagnetic problem in metal and the so-called 1D conducting line model can be applied instead of a full 3D space description. Further, a TE/TM (''transverse electric - transverse magnetic'') splitting implicit numerical scheme along with 1D conducting line model is applied to develop a new longitudinally dispersion-free hybrid numerical scheme in the time domain. The stability of the new hybrid numerical scheme in vacuum, conductor and bound cell is studied. The convergence of the new scheme is analyzed by comparison with the well-known analytical solutions. The wakefield calculations for a number of

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

    OpenAIRE

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

    2005-01-01

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

  9. Thermophilic anaerobic co-digestion of oil palm empty fruit bunches with palm oil mill effluent for efficient biogas production

    DEFF Research Database (Denmark)

    O-Thong, Sompong; Boe, Kanokwan; Angelidaki, Irini

    2012-01-01

    The effect of pretreatment methods for improved biodegradability and biogas production of oil palm empty fruit bunches (EFB) and its co-digestion with palm oil mill effluent (POME) was investigated. The maximum methane potential of POME was 502mL CH4/gVS-added corresponding to 33.2m3 CH4/ton POME...

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

    Science.gov (United States)

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

    2012-12-01

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

  11. Study on formation of step bunching on 6H-SiC (0001) surface by kinetic Monte Carlo method

    Science.gov (United States)

    Li, Yuan; Chen, Xuejiang; Su, Juan

    2016-05-01

    The formation and evolution of step bunching during step-flow growth of 6H-SiC (0001) surfaces were studied by three-dimensional kinetic Monte Carlo (KMC) method and compared with the analytic model based on the theory of Burton-Cabera-Frank (BCF). In the KMC model the crystal lattice was represented by a structured mesh which fixed the position of atoms and interatomic bonding. The events considered in the model were adatoms adsorption and diffusion on the terrace, and adatoms attachment, detachment and interlayer transport at the step edges. In addition, effects of Ehrlich-Schwoebel (ES) barriers at downward step edges and incorporation barriers at upwards step edges were also considered. In order to obtain more elaborate information for the behavior of atoms in the crystal surface, silicon and carbon atoms were treated as the minimal diffusing species. KMC simulation results showed that multiple-height steps were formed on the vicinal surface oriented toward [ 1 1 bar 00 ] or [ 11 2 bar 0 ] directions. And then the formation mechanism of the step bunching was analyzed. Finally, to further analyze the formation processes of step bunching, a one-dimensional BCF analytic model with ES and incorporation barriers was used, and then it was solved numerically. In the BCF model, the periodic boundary conditions (PBC) were applied, and the parameters were corresponded to those used in the KMC model. The evolution character of step bunching was consistent with the results obtained by KMC simulation.

  12. A Single-Shot Method for Measuring Femtosecond Bunch Length in Linac-Based Free-Electron Lasers

    International Nuclear Information System (INIS)

    There is growing interest in the generation and characterization of femtosecond and subfemtosecond pulses from linac-based free-electron lasers (FELs). In this report, following the method of Ricci and Smith (Phys. Rev. ST Accel. Beams 3, 032801 (2000)), we investigate the measurement of the longitudinal bunch profile of an ultrashort electron bunch produced by these FELs. We show that this method can be applied in a straightforward manner at x-ray FEL facilities such as the Linac Coherent Light Source by slightly adjusting the second bunch compressor followed by running the bunch on an rf zero-crossing phase of the final linac. We find that the linac wakefield strongly perturbs the measurement, and through analysis show that it can be compensated in a simple way. We demonstrate the effectiveness of this method and wakefield compensation through numerical simulations, including effects of coherent synchrotron radiation and longitudinal space charge. When used in conjunction with a high-resolution electron spectrometer, this method potentially reveals the temporal profile of the electron beam down to the femtosecond and subfemotsecond scale.

  13. A two-step method for retrieving the longitudinal profile of an electron bunch from its coherent radiation

    Energy Technology Data Exchange (ETDEWEB)

    Pelliccia, Daniele [School of Physics, Monash University, Victoria 3800 (Australia); Sen, Tanaji [Accelerator Physics Center, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States)

    2014-11-11

    The coherent radiation emitted by an electron bunch provides a diagnostic signal that can be used to estimate its longitudinal distribution. Commonly only the amplitude of the intensity spectrum can be measured and the associated phase must be calculated to obtain the bunch profile. Very recently an iterative method was proposed to retrieve this phase. However ambiguities associated with non-uniqueness of the solution are always present in the phase retrieval procedure. Here we present a method to overcome the ambiguity problem by first performing multiple independent runs of the phase retrieval procedure and then second, sorting the good solutions by means of cross-correlation analysis. Results obtained with simulated bunches of various shapes and experimental measured spectra are presented, discussed and compared with the established Kramers–Kronig method. It is shown that even when the effect of the ambiguities is strong, as is the case for a double peak in the profile, the cross-correlation post-processing is able to filter out unwanted solutions. We show that, unlike the Kramers–Kronig method, the combined approach presented is able to faithfully reconstruct complicated bunch profiles.

  14. 4-Hydroxybenzoic acid from hydrothermal pretreatment of oil palm empty fruit bunches - Its origin and influence on biomass conversion

    DEFF Research Database (Denmark)

    Rasmussen, Helena; Mogensen, Kit H.; Jeppesen, Martin D.;

    2016-01-01

    or fucose, e.g. pectin rich biomasses. Assessment of the influence of 4-hydroxybenzoic acid in the enzymatic hydrolysis of pretreated oil palm empty fruit bunches as well as its presence during fermentation showed that 4-hydroxybenzoic acid is not inhibiting or mediating neither on the enzymatic hydrolysis...

  15. Investigation of the phase space distribution of electron bunches at the FLASH-linac using a transverse deflecting structure

    Energy Technology Data Exchange (ETDEWEB)

    Roehrs, M.

    2008-06-15

    The operation of a high-gain free-electron laser (FEL) puts stringent demands on the peak current, transverse emittance and energy spread of the electron beam. At the Free Electron Laser in Hamburg (FLASH), a transverse deflecting structure (TDS) has been installed to investigate these electron beam parameters. The radio-frequency electromagnetic field in the TDS is utilized to deflect the beam electrons vertically as a function of time so that the charge distribution in the longitudinal-horizontal plane can be imaged with optical transition radiation screens. Using this technique, the single-bunch current profile was measured with an unprecedented resolution of about 10 {mu}m (30 fs) under FEL operating conditions. A precise single-shot measurement of the energy distribution along a bunch was accomplished by using the TDS in combination with an energy spectrometer. Appropriate variations of the focal strengths of quadrupole magnets allowed for the measurement of the horizontal emittance as a function of the longitudinal position within a bunch (slice emittance) with a longitudinal resolution in the order of 10 {mu}m. While the slice emittance in the peak current region was measured to be significantly larger than deduced from properties of the FEL radiation, tomographic methods revealed a bunch region of small horizontal emittance and high current. The observed increase in slice emittance in the peak current region was found to be caused by coherent emission of synchrotron radiation within bending magnets. (orig.)

  16. Delignification outperforms alkaline extraction for xylan fingerprinting of oil palm empty fruit bunch.

    Science.gov (United States)

    Murciano Martínez, Patricia; Kabel, Mirjam A; Gruppen, Harry

    2016-11-20

    Enzyme hydrolysed (hemi-)celluloses from oil palm empty fruit bunches (EFBs) are a source for production of bio-fuels or chemicals. In this study, after either peracetic acid delignification or alkaline extraction, EFB hemicellulose structures were described, aided by xylanase hydrolysis. Delignification of EFB facilitated the hydrolysis of EFB-xylan by a pure endo-β-1,4-xylanase. Up to 91% (w/w) of the non-extracted xylan in the delignified EFB was hydrolysed compared to less than 4% (w/w) of that in untreated EFB. Alkaline extraction of EFB, without prior delignification, yielded only 50% of the xylan. The xylan obtained was hydrolysed only for 40% by the endo-xylanase used. Hence, delignification alone outperformed alkaline extraction as pretreatment for enzymatic fingerprinting of EFB xylans. From the analysis of the oligosaccharide-fingerprint of the delignified endo-xylanase hydrolysed EFB xylan, the structure was proposed as acetylated 4-O-methylglucuronoarabinoxylan.

  17. A Wideband Slotted Kicker Design for SPS Transverse Intra-Bunch Feedback

    CERN Document Server

    Cesaratto, John M; DeSantis, S; Drago, A; Fox, J D; Gallo, A; Hofle, W; Marcellini, F; Rivetta, C H; Zobov, M

    2013-01-01

    Control and mitigation of transverse beam instabilities caused by electron cloud and TMCI will be essential for the SPS to meet the beam intensity demands for the HL-LHC upgrade. A wideband intra-bunch feedback method is in development, based on a 4 GS/s data acquisition and processing, and with a back end frequency structure extending to 1 GHz. A slotted type kicker, similar to those used for stochastic cooling, has been considered as the terminal element of the feedback chain. It offers the most promising deflecting structure characteristics to meet the system requirements in terms of bandwidth, shunt impedance, and beam coupling impedance. Different types of slotted structures have been explored and simulated, including a ridged waveguide and coaxial type waveguide. In this paper we present our findings and the conceptual design of a vertical SPS wideband kicker consistent with the stay clear, vacuum, frequency band coverage, and peak shunt impedance requirements.

  18. X-ray analog pixel array detector for single synchrotron bunch time-resolved imaging

    CERN Document Server

    Koerner, Lucas J

    2010-01-01

    Dynamic x-ray studies may reach temporal resolutions limited by only the x-ray pulse duration if the detector is fast enough to segregate synchrotron pulses. An analog integrating pixel array detector with in-pixel storage and temporal resolution of around 150 ns, sufficient to isolate pulses, is presented. Analog integration minimizes count-rate limitations and in-pixel storage captures successive pulses. Fundamental tests of noise and linearity as well as high-speed laser measurements are shown. The detector resolved individual bunch trains at the Cornell High Energy Synchrotron Source (CHESS) at levels of up to 3.7x10^3 x-rays/pixel/train. When applied to turn-by-turn x-ray beam characterization single-shot intensity measurements were made with a repeatability of 0.4% and horizontal oscillations of the positron cloud were detected. This device is appropriate for time-resolved Bragg spot single crystal experiments.

  19. Abrasive wear: The efects of fibres size on oil palm empty fruit bunch polyester composite

    Science.gov (United States)

    Kasolang, S.; Kalam, A.; Ahmad, M. A.; Rahman, N. A.; Suhadah, W. N.

    2012-06-01

    This paper presents an experimental investigation carried out to determine the effect of palm oil empty fruit bunch (OPEFB) fibre size in dry sliding testing of polyester composite. These composite samples were produced by mixing raw OPEFB fibre with resin. The samples were prepared at different sizes of fibre (100, 125, 180 and 250μm). Abrasion Resistance Tester (TR-600) was used to carried out abrasive wear tests in dry sliding conditions. These tests were performed at room temperature for two different loads (10 and 30N) and at a constant sliding velocity of 1.4m/s. The specific wear rates of OPEFB polyester composites were obtained. The morphology of composite surface before and after tests was also examined using 3D microscope imaging. Preliminary work on thermal distribution at the abrasive wheel point was also conducted for selected samples.

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

    Science.gov (United States)

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

    2016-09-01

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