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Sample records for bunching

  1. 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)

  2. 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.

  3. Study on ILC bunch compressor

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In this paper, we have found a new set of parameters for the short two-stage ILC bunch compres-sors. The RF sections are both in the accelerating phase rather than the decelerating phase to improve the accelerating efficiency. We have also studied the CSR related issues. The results show that the microbunch instability exists extensively in the second bunch compressor, but the emittance dilution is small due to the relatively long bunch.

  4. CEBAF Upgrade Bunch Length Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Ahmad, Mahmoud [Old Dominion Univ., Norfolk, VA (United States)

    2016-05-01

    Many accelerators use short electron bunches and measuring the bunch length is important for efficient operations. CEBAF needs a suitable bunch length because bunches that are too long will result in beam interruption to the halls due to excessive energy spread and beam loss. In this work, bunch length is measured by invasive and non-invasive techniques at different beam energies. Two new measurement techniques have been commissioned; a harmonic cavity showed good results compared to expectations from simulation, and a real time interferometer is commissioned and first checkouts were performed. Three other techniques were used for measurements and comparison purposes without modifying the old procedures. Two of them can be used when the beam is not compressed longitudinally while the other one, the synchrotron light monitor, can be used with compressed or uncompressed beam.

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

    CERN Document Server

    Bartosik, H

    2012-01-01

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

  6. 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.

  7. 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.

  8. STOCHASTIC COOLING FOR BUNCHED BEAMS.

    Energy Technology Data Exchange (ETDEWEB)

    BLASKIEWICZ, M.

    2005-05-16

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

  9. Multi-bunch Feedback Systems

    CERN Document Server

    Lonza, M

    2014-01-01

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

  10. Dechirper Wakefields for Short Bunches

    CERN Document Server

    Bane, Karl

    2016-01-01

    In previous work [1] general expressions, valid for arbitrary bunch lengths, were derived for the wakefields of corrugated structures with flat geometry, such as is used in the RadiaBeam/LCLS dechirper. However, the bunch at the end of linac-based X-ray FELs--like the LCLS--is extremely short, and for short bunches the wakes can be considerably simplified. In this work, we first derive analytical approximations to the short-range wakes. These are generalized wakes, in the sense that their validity is not limited to a small neighborhood of the symmetry axis, but rather extends to arbitrary transverse offsets of driving and test particles. The validity of these short-bunch wakes holds not only for the corrugated structure, but rather for any flat structure whose beam-cavity interaction can be described by a surface impedance. We use these wakes to obtain, for a short bunch passing through a dechirper: estimates of the energy loss as function of gap, the transverse kick as function of beam offset, the slice ener...

  11. 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.

  12. Longitudinal Single Bunch Instability Study on BEPCII

    CERN Document Server

    Dou, Wang; Zhe, Duan; Na, Wang; Li, Wang; Lin, Wang; Jie, Gao

    2013-01-01

    In order to study the single bunch longitudinal instability in BEPCII, experiments on the positron ring (BPR) for the bunch lengthening phenomenon were made. By analyzing the experimental data based on Gao's theory, the longitudinal loss factor for the bunch are obtained. Also, the total wake potential and the beam current threshold are estimated.

  13. Turn-by-Turn and Bunch-by-Bunch Transverse Profiles of a Single Bunch in a Full Ring

    Energy Technology Data Exchange (ETDEWEB)

    Kraus, R.; /Nevada U., Reno; Fisher, A.S.; /SLAC

    2005-12-15

    The apparatus described in this paper can image the evolution of the transverse profile of a single bunch, isolated from a full PEP-II ring of 1500 bunches. Using this apparatus there are two methods of single bunch imaging; bunch-by-bunch beam profiling can image every bunch in the ring a single bunch at a time with the images of sequential bunches being in order, allowing one to see variations in beam size along a train. Turn-by-turn beam profiling images a single bunch on each successive turn it makes around the ring. This method will be useful in determining the effect that an injected bunch has on a stable bunch as the oscillations of the injected bunch damp out. Turn-by-turn imaging of the synchrotron light uses a system of lenses and mirrors to image many turns of both the major and minor axis of a single bunch across the photocathode of a gateable camera. The bunch-by-bunch method is simpler: because of a focusing mirror used in porting the light from the ring, the synchrotron light from the orbiting electrons becomes an image at a certain distance from the mirror; and since the camera does not use a lens, the photocathode is set exactly at this image distance. Bunch-by-bunch profiling has shown that in the Low Energy Ring (LER) horizontal bunch size decreases along a train. Turn-by-turn profiling has been able to image 100 turns of a single bunch on one exposure of the camera. The turn-by-turn setup has also been able to image 50 turns of the minor axis showing part of the damping process of an oscillating injected charge during a LER fill. The goal is to image the damping of oscillations of injected charge for 100 turns of both the major and minor axis throughout the damping process during trickle injection. With some changes to the apparatus this goal is within reach and will make turn-by-turn imaging a very useful tool in beam diagnostics.

  14. 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.

  15. Dynamics of Femtosecond Electron Bunches

    OpenAIRE

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

    2007-01-01

    In the laser wakefield accelerator (LWFA) a short intense laser pulse, with a duration of the order of a plasma wave period, excites an unusually strong plasma wake wave (laser wakefield). Recent experiments on laser wakefield acceleration [Nature (London) 431, p.535, p.538, p.541 (2004)] demonstrated generation of ultra-short (with a duration of a few femtoseconds) relativistic electron bunches with relatively low energy spread of the order of a few percent. We have studied the dynamics of s...

  16. 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.

  17. TRANSVERSE MODES FOR FLAT INTER-BUNCH WAKES*

    CERN Document Server

    Burov, A

    2013-01-01

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

  18. 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.

  19. LHC MD 1279: Bunch Flattening in Physics

    CERN Document Server

    AUTHOR|(CDS)2073675; Baudrenghien, Philippe; Esteban Muller, Juan; Shaposhnikova, Elena; CERN. Geneva. ATS Department

    2017-01-01

    Vertex reconstruction is not accurate enough for LHCb when the bunch length in physics shrinks below about 0.9 ns. The end-of-fill MD studies presented here proved that bunch flattening using sinusoidal RF modulation is a loss-free method to increase the r.m.s. bunch length and flatten the bunch profile. Furthermore, the optimum modulation parameters to be used in physics have been identified. Subsequently, bunch flattening in physics was used operationally with a modulation frequency of 98.75 % of the central synchrotron frequency and 0.6 modulation amplitude, resulting in a 150-200 ps increase in the BQM-measured bunch length. A ‘mid-of-fill’ test at arrival to flat top revealed that also the bunch distribution created by the controlled emittance blow-up during the ramp is affected when bunch flattening is applied. The measurements took place on 17th June and the 4th, 7th and 22nd July 2016. Operational cases are shown as well.

  20. Femtosecond electron bunches, source and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Thongbai, C. [FNRF, Department of Physics, Chiang Mai University, Chiangmai 50200 (Thailand)], E-mail: chlada@chiangmai.ac.th; Kusoljariyakul, K. [FNRF, Department of Physics, Chiang Mai University, Chiangmai 50200 (Thailand); Rimjaem, S. [DESY Zeuthen, Platanenallee 6, Zeuthen 15738 (Germany); Rhodes, M.W. [IST, Chiang Mai University, Chiangmai 50200 (Thailand); Saisut, J. [FNRF, Department of Physics, Chiang Mai University, Chiangmai 50200 (Thailand); Thamboon, P.; Wichaisirimongkol, P. [IST, Chiang Mai University, Chiangmai 50200 (Thailand); Vilaithong, T. [FNRF, Department of Physics, Chiang Mai University, Chiangmai 50200 (Thailand)

    2008-03-11

    A femtosecond electron source has been developed at the Fast Neutron Research Facility (FNRF), Chiang Mai University, Thailand. So far, it has produced electron bunches as short as {sigma}{sub z}{approx}180 fs with (1-6)x10{sup 8} electrons per microbunch. The system consists of an RF-gun with a thermionic cathode, an alpha-magnet as a magnetic bunch compressor, and a linear accelerator as a post acceleration section. Coherent transition radiation emitted at wavelengths equal to and longer than the bunch length is used in a Michelson interferometer to determine the bunch length by autocorrelation technique. The experimental setup and results of the bunch length measurement are described.

  1. Tevatron bunch length studies at CDF

    Energy Technology Data Exchange (ETDEWEB)

    Matthew Jones; Bob Kephart; and Rick Vidal

    2002-05-29

    A luminous interaction region can be described by the distribution in (x, y, z) over which p{bar p} interactions are observed in a detector. The spatial size of this distribution can be written in terms of expressions that involve only combinations of the proton and anti-proton bunch sizes. Hence, it is not possible to determine the sizes of the proton and anti-proton bunches independently by fitting the distribution of (x, y, z) from the recorded events. If, in addition to the coordinates (x, y, z) at which p{bar p} interactions occur, the times at which the interactions took place are also measured, then it becomes possible to measure the lengths of the proton and anti-proton bunches separately. This sensitivity is due to a correlation between z and t that arises from the fact that the proton and anti-proton bunches travel in opposite directions. The derivation presented in section 2 quantifies this correlation, resulting in an expression for the probability density as a function of z and t for p{bar p} interactions. By fitting the distributions observed at CDF using this model, we measure the lengths of the proton and anti-proton bunches at times throughout several Tevatron stores. From this analysis the evolution of the bunch lengths can be studied. We attempt to correlate these with other measures of the bunch length obtained using different experimental techniques.

  2. 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.

  3. 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.

  4. 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.

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

    CERN Document Server

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

    2002-01-01

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

  6. 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.

  7. 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.

  8. LHC Longitudinal Single-Bunch Stability Threshold

    CERN Document Server

    Esteban Muller, Juan Federico; Baudrenghien, Philippe; Lasheen, Alexandre; Roggen, Toon; Shaposhnikova, Elena; Timko, Helga; CERN. Geneva. ATS Department

    2016-01-01

    The aim of the MD studies presented here was to determine with a reasonable accuracy the single-bunch longitudinal stability threshold in the LHC. The measurements were performed by placing along the ring 8 or 20 ‘single’ bunches with different intensities but similar longitudinal emittances. Then they were accelerated and bunch stability was observed at arrival to flat top. Combining the results of two measurement sessions, the single bunch stability threshold is estimated to be (2.4 ± 0.2) × 10^11 ppb for an emittance of 1.89 eVs (1.0 ns) at 6.5 TeV with 12 MV RF voltage. Measurements were taken during the MD session MD472 from 22:00 on 20th to 05:00 on 21st July 2015 and session MD365 from 17:00 on 26th to 01:00 on 27th August 2015.

  9. Space Charge Mitigation With Longitudinally Hollow Bunches

    CERN Document Server

    Oeftiger, Adrian; Rumolo, Giovanni; CERN. Geneva. ATS Department

    2016-01-01

    Suitably, hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN’s PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.

  10. Space Charge Mitigation With Longitudinally Hollow Bunches

    CERN Multimedia

    Oeftiger, Adrian; Rumolo, Giovanni

    2016-01-01

    Hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN’s PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.

  11. 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.

  12. 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

  13. 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.

  14. COMMISSIONING OF THE DIGITAL TRANSVERSE BUNCH-BY-BUNCH FEEDBACK SYSTEM FOR THE TLS.

    Energy Technology Data Exchange (ETDEWEB)

    HU, K.H.; KUO, C.H.; CHOU, P.J.; LEE, D.; HSU, S.Y.; CHEN, J.; WANG, C.J.; HSU, K.T.; KOBAYASHI, K.; NAKAMURA, T.; CHAO, A.W.; WENG, W.T.

    2006-06-26

    Multi-bunch instabilities degrade beam quality through increased beam emittance, energy spread and even beam loss. Feedback systems are used to suppress multi-bunch instabilities associated with the resistive wall of the beam ducts, cavity-like structures, and trapped ions. A new digital transverse bunch-by-bunch feedback system has recently been commissioned at the Taiwan Light Source, and has replaced the previous analog system. The new system has the advantages that it enlarges the tune acceptance and improves damping for transverse instability at high currents, such that top-up operation is achieved. After a coupled-bunch transverse instability was suppressed, more than 350 mA was successfully stored during preliminary commissioning. In this new system, a single feedback loop simultaneously suppresses both horizontal and vertical multi-bunch instabilities. Investigating the characteristics of the feedback loop and further improving the system performances are the next short-term goals. The feedback system employs the latest generation of field-programmable gate array (FPGA) processor to process bunch signals. Memory has been installed to capture up to 250 msec of bunch oscillation signal, considering system diagnostics suitable to support various beam physics studies.

  15. 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.}

  16. Microwave measurement of intra bunch charge distributions

    CERN Document Server

    Dehler, M

    2003-01-01

    A direct way of obtaining intra bunch charge distributions is to measure the amplitude roll off as well as the phase behavior of the spectrum of the single bunch self field. To that effect, a microwave pickup together with a microwave front end has been installed in the storage ring of the Swiss Light Source (SLS). As pickup, button type bpms are used, which have been designed for a broad band behavior in the excess of 30 GHz. Three bpms together with their individual front ends are used in order to sample the beam spectrum at frequencies of 6, 12 and 18 GHz, which compares to the standard spectrum of a 1 mA single bunch extending to approximately 12 GHz (13 ps rms bunch length). The signals are mixed to base band in loco using the multiplied RF frequency as a LO. By shifting the LO phase, simultaneously the amplitude roll off as well the complex phase of the beam spectrum can be obtained. Where using a resonator as a pickup would smear out the response over several bunches, allowing only the determination of...

  17. Probing the LHC impedance with single bunches

    CERN Document Server

    Esteban Müller, J F; Bohl, T; Bhat, C; Calaga, R; Kain, V; Kuhn, M; Mounet, N; Papotti, G; Shaposhnikova, E; Timko, H

    2013-01-01

    The main purpose of this MD was to study longitudinal and transverse beam dynamics in the LHC. Eight bunches with different bunch lengths and intensities were injected into the LHC in two fills. The distance between bunches is large enough so they can be treated as single bunches. The bunch length and the intensity were adjusted in the SPS by applying controlled longitudinal emittance blow-up with different amplitudes and transverse scraping. The aim of the first fill was to measure the longitudinal and the transverse impedance at injection energy (450 GeV). The second fill of the MD included acceleration to 4 TeV and was used to study the loss of Landau damping during the ramp, observed as dipole and quadrupole oscillations, and to measure the impedance at top energy. Measurements of synchronous phase shift and peak-detected Schottky spectra were taken during both fills in order to estimate the longitudinal impedance and they are presented in this Note. We also show the transverse emittance evolution during ...

  18. Gyrophase bunched ions in the plasma sheet

    Science.gov (United States)

    Wang, Zhiqiang; Zhai, Hao; Gao, Zhuxiu; Huang, Chaoyan

    2017-01-01

    Gyrophase bunched ions were first detected in the upstream region of the Earth's bow shock in the early 1980s which is formed by the microphysical process associated with reflected solar wind ions at the bow shock. Inside the magnetosphere, the results of computer simulations demonstrated that nonlinear wave-particle interaction can also result in the gyrophase bunching of particles. However, to date direct observations barely exist regarding this issue occurred inside the magnetosphere. In this paper, we report for the first time an event of gyrophase bunched ions observed in the near-Earth plasma sheet. The nongyrotropic distributions of ions were closely accompanied with the electromagnetic waves at the oxygen cyclotron frequency. The phase of bunched ions and the phase of waves mainly have very narrow phase differences (helicity with respect to the propagation direction, which agrees with the characteristic of electromagnetic ion cyclotron waves. The observation of O+ ions composition suggests that the oxygen band waves are excited due to the enhancements of the O+ ion density. This study suggests that the gyrophase bunching is a significant nonlinear effect that exists not only in the bow shock but also in the inner magnetosphere.

  19. Measurement of Satellite Bunches at the LHC

    CERN Document Server

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

    2012-01-01

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

  20. 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.

  1. 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...

  2. Sub-fs Electron Bunch Generation with Sub-10-fs Bunch Arrival-Time Jitter via Bunch Slicing in a Magnetic Chicane

    OpenAIRE

    Zhu, Jun; Assmann, R W.; Dohlus, M.; Dorda, U.; Marchetti, Barbara

    2016-01-01

    The generation of ultra-short electron bunches with ultra-small bunch arrival-time jitter is of vital importance for Laser-plasma wake field acceleration (LWFA) with external injection. We study the production of 100-MeV electron bunches with bunch durations of sub-femtosecond (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 tw...

  3. FOCUSING AND ACCELERATION OF BUNCHED BEAMS

    Energy Technology Data Exchange (ETDEWEB)

    PARSA,Z.; ZADOROZHNY,V.

    2000-04-07

    A new approach to solving the kinetic equation for the beam distribution function, (very useful from the practical point of view), is discussed, in which the authors also obtain a complement to the Skrinsky's condition for the self-focused bunched beam. This problem belongs to the theory of nonlinear systems in which both regular and chaotic motion is possible. The kinetic approach, based on Vlasov-Poisson equations, are used to investigate the focusing and acceleration of bunched beam. Special attention is given to the studies of stability in a bunched beam by means of the two norm, which may be used to describe t!he motion of high-energy particles.

  4. Wakefields of Sub-Picosecond Electron Bunches

    Energy Technology Data Exchange (ETDEWEB)

    Bane, Karl L.F.; /SLAC

    2006-04-19

    We discuss wakefields excited by short bunches in accelerators. In particular, we review some of what has been learned in recent years concerning diffraction wakes, roughness impedance, coherent synchrotron radiation wakes, and the resistive wall wake, focusing on analytical solutions where possible. As examples, we apply formulas for these wakes to various parts of the Linac Coherent Light Source (LCLS) project. The longitudinal accelerator structure wake of the SLAC linac is an important ingredient in the LCLS bunch compression process. Of the wakes in the undulator region, the dominant one is the resistive wall wake of the beam pipe.

  5. 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.

  6. Longitudinal Beam Diagnostics for the ILC Injectors and Bunch Compressors

    Energy Technology Data Exchange (ETDEWEB)

    Piot, Philippe [Northern Illinois U.; Bracke, Adam [Northern Illinois U.; Demir, Veysel [Northern Illinois U.; Maxwell, Timothy [Fermilab; Rihaoui, Marwan [Argonne; Jing, Chunguang [Euclid Techlabs, Solon; Power, John [Argonne

    2010-12-01

    We present a diagnostics suite and analyze techniques for setting up the longitudinal beam dynamics in ILC e⁻ injectors and e⁺ and e⁻ bunch compressors. Techniques to measure the first order moments and recover the first order longitudinal transfer map of the injector's intricate bunching scheme are presented. Coherent transition radiation diagnostics needed to measure and monitor the bunch length downstream of the ~5 GeV bunch compressor are investigated using a vector diffraction model.

  7. Interaction of ultrarelativistic electron and proton bunches with dense plasmas

    CERN Document Server

    Rukhadze, A A

    2012-01-01

    Here we discuss the possibility of employment of ultrarelativistic electron and proton bunches for generation of high plasma wakefields in dense plasmas due to the Cherenkov resonance plasma-bunch interaction. We estimate the maximum amplitude of such a wake and minimum system length at which the maximum amplitude can be generated at the given bunch parameters.

  8. 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.

  9. The Case: Bunche-Da Vinci Learning Partnership Academy

    Science.gov (United States)

    Eisenberg, Nicole; Winters, Lynn; Alkin, Marvin C.

    2005-01-01

    The Bunche-Da Vinci case described in this article presents a situation at Bunche Elementary School that four theorists were asked to address in their evaluation designs (see EJ791771, EJ719772, EJ791773, and EJ792694). The Bunche-Da Vinci Learning Partnership Academy, an elementary school located between an urban port city and a historically…

  10. Formation of step bunches induced by flow in solution

    OpenAIRE

    Inaba, Masashi; Sato, Masahide

    2012-01-01

    We study the formation of step bunches induced by flow in solution during growth. In our previous study [M. Inaba and M. Sato: J. Phys. Soc. Jpn. 80 (2011) 074606], we showed that the step-down flow in solution causes bunching. In this research, we study the dependence of step behavior on some parameters. With a slow flow, the separation and coalescence between steps and bunches occur frequently during step bunching. With increasing flow rate, the frequency decreases and tight bunches are for...

  11. A Two Bunch Beam Position Monitor

    Energy Technology Data Exchange (ETDEWEB)

    Medvedko, E.; Aiello, R.; Smith, S.; /SLAC

    2011-09-12

    A new beam position monitor digitizer module has been designed, tested and tuned at SLAC. This module, the electron-positron beam position monitor (epBPM), measures position of single electron and positron bunches for the SLC, LINAC, PEPII injections lines and final focus. The epBPM has been designed to improve resolution of beam position measurements with respect to existing module and to speed feedback correction. The required dynamic range is from 5 x 10{sup 8} to 10{sup 11} particles per bunch (46dB). The epBPM input signal range is from {+-}2.5 mV to {+-}500 mV. The pulse-to-pulse resolution is less than 2 {mu}m for 5 x 10{sup 10} particles per bunch for the 12 cm long striplines, covering 30{sup o} at 9 mm radius. The epBPM module has been made in CAMAC standard, single width slot, with SLAC type timing connector. 45 modules have been fabricated. The epBPM module has four input channels X{sup +}, X{sup -}, Y{sup +}, Y{sup -} (Fig. 1), named to correspond with coordinates of four striplines - two in horizontal and two in vertical planes, processing signals to the epBPM inputs. The epBPM inputs are split for eight signal processing channels to catch two bunches, first - the positron, then the electron bunch in one cycle of measurements. The epBPM has internal and external trigger modes of operations. The internal mode has two options - with or without external timing, catching only first bunch in the untimed mode. The epBPM has an on board calibration circuit for measuring gain of the signal processing channels and for timing scan of programmable digital delays to synchronize the trigger and the epBPM input signal's peak. There is a mode for pedestal measurements. The epBPM has 3.6 {mu}s conversion time.

  12. 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.

  13. 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}

  14. 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.

  15. 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.

  16. Bunch Profiling Using a Rotating Mask

    Energy Technology Data Exchange (ETDEWEB)

    Miller, Mitchell; /SLAC /IIT, Chicago

    2012-08-24

    The current method for measuring profiles of proton bunches in accelerators is severely lacking. One must dedicate a great deal of time and expensive equipment to achieve meaningful results. A new method to complete this task uses a rotating mask with slots of three different orientations to collect this data. By scanning over the beam in three different directions, a complete profile for each bunch is built in just seconds, compared to the hours necessary for the previous method. This design was successfully tested using synchrotron radiation emitted by SPEAR3. The profile of the beam was measured in each of the three desired directions. Due to scheduled beam maintenance, only one set of data was completed and more are necessary to solve any remaining issues. The data collected was processed and all of the RMS sizes along the major and minor axes, as well as the tilt of the beam ellipse were measured.

  17. 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.

  18. 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.

  19. Bunch cleaning strategies and experiments at the Advanced Photon Source.

    Energy Technology Data Exchange (ETDEWEB)

    Sereno, N. S.

    1999-04-15

    The Advanced Photon Source (APS) design incorporated a positron accumulator ring (PAR) as part of the injector chain. In order to increase reliability and accommodate other uses of the injector, APS will run with electrons, eliminating the need for the PAR, provided another method of eliminating rf bucket pollution in the APS is found. Satellite bunches captured from an up to 30-ns-long beam from the linac need to be removed in the injector synchrotron and storage ring. The bunch cleaning method considered here relies on driving a stripline kicker with an amplitude modulated (AM) carrier signal where the carrier is at a revolution harmonic sideband corresponding to the vertical tune. The envelope waveform is phased so that all bunches except a single target bunch (eventually to be injected into the storage ring) are resonated vertically into a scraper. The kicker is designed with a large enough shunt impedance to remove satellite bunches from the injection energy of 0.4 GeV up to 1 GeV. Satellite bunch removal in the storage ring relies on the single bunch current tune shift resulting from the machine impedance. Small bunches remaining after initial preparation in the synchrotron may be removed by driving the beam vertically into a scraper using a stripline kicker operating at a sideband corresponding to the vertical tune for small current bunches. In this paper both design specifications and bunch purity measurements are reported for both the injector synchrotron and storage ring.

  20. 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].

  1. Design of BEPC Ⅱ bunch current monitor system

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lei; MA Hui-Zhou; YUE Jun-Hui; LEI Ge; CAO Jian-She; MA Li

    2008-01-01

    BEPC Ⅱ is an electron-positron collider designed to run under multi-bunches and high beam current condition. The accelerator consists of an electron ring, a positron ring and a linear injector. In order to achieve the target luminosity and implement the equal bunch charge injection, the Bunch Current Monitor (BCM)system is built on BEPC Ⅱ. The BCM system consists of three parts: the front-end circuit, the bunch current acquisition system and the bucket selection system. The control software of BCM is based on VxWorks and EPICS. With the help of BCM system, the bunch current in each bucket can be monitored in the Central Control Room. The BEPC Ⅱ timing system can also use the bunch current database to decide which bucket needs to refill to implement "top-off" injection.

  2. Femtosecond electron-bunch dynamics in laser wakefields and vacuum

    OpenAIRE

    Khachatryan, A. G.; Irman, A.; Goor, van de, AAAM; Boller, K. -J.

    2007-01-01

    Recent advances in laser wakefield acceleration demonstrated the generation of extremely short (with a duration of a few femtoseconds) relativistic electron bunches with relatively low (of the order of couple of percent) energy spread. In this article we study the dynamics of such bunches in drift space (vacuum) and in channel-guided laser wakefields. Analytical solutions were found for the transverse coordinate of an electron and for the bunch envelope in the wakefield in the case of arbitra...

  3. Tax Bunching, Income Shifting and Self-employment

    DEFF Research Database (Denmark)

    le Maire, Christian Daniel; Schjerning, Bertel

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

  4. Tax Bunching, Income Shifting and Self-employment

    DEFF Research Database (Denmark)

    le Maire, Christian Daniel; Schjerning, Bertel

    2013-01-01

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

  5. Effect of the induced field memory on the bunch lengthening

    Energy Technology Data Exchange (ETDEWEB)

    Pestrikov, D.V., E-mail: pestrikov@inp.nsk.su

    2015-02-11

    We study the variations of the solutions to the Haissinski equation versus the duration of the memory of the longitudinal induced fields. For simplicity, we assume that a single bunch in a storage ring interacts with surrounding electrodes, which electromagnetically are equivalent to a parallel LR-circuit. For this particular case, we have found out that controlling the decay time of the bunch induced fields we can substantially affect the length of the bunch as well as the features of Landau damping of coherent oscillations of the bunch.

  6. POSITION DETERMINATION OF CLOSELY SPACED BUNCHES USING CAVITY BPMs

    CERN Document Server

    Joshi, N; Cullinan, F; Lyapin, A

    2011-01-01

    Radio Frequency (RF) Cavity Beam Position Monitor (BPM) systems form a major part of precision position measurement diagnostics for linear accelerators with low emittance beams. Using cavity BPMs, a position resolution of less than 100 nm has been demonstrated in single bunch mode operation. In the case of closely spaced bunches, where the decay time of the cavity is comparable to the time separation between bunches, the BPM signal from a bunch is polluted by the signal induced by the previous bunches in the same bunch-train. This paper discusses our ongoing work to develop the methods to extract the position of closely spaced bunches using cavity BPMs. A signal subtraction code is being developed to remove the signal pollution from previous bunches and to determine the individual bunch position. Another code has been developed to simulate the BPM data for the cross check. Performance of the code is studied on the experimental and simulated data. Application of the analysis techniques to the linear colliders,...

  7. Beam transport and bunch compression at TARLA

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-10-21

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

  8. 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...

  9. Femtosecond electron-bunch dynamics in laser wakefields and vacuum

    NARCIS (Netherlands)

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

    2007-01-01

    Recent advances in laser wakefield acceleration demonstrated the generation of extremely short (with a duration of a few femtoseconds) relativistic electron bunches with relatively low (of the order of couple of percent) energy spread. In this article we study the dynamics of such bunches in drift s

  10. Coupled-Beam and Coupled-Bunch Instabilities

    Energy Technology Data Exchange (ETDEWEB)

    Burov, Alexey [Fermilab

    2016-06-23

    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.

  11. 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.

  12. 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.

  13. 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.

  14. 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 ...

  15. ACHROMAT WITH LINEAR SPACE CHARGE FOR BUNCHED BEAMS

    Energy Technology Data Exchange (ETDEWEB)

    RAPARIA,D.; ALESSI,J.G.; LEE,Y.Y.; WENG,W.T.

    1998-08-23

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

  16. A Proof of Principle of Asymmetric Bunch Pair Merging

    CERN Document Server

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

    2003-01-01

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

  17. Synchronization of Synchrotrons for bunch-to-bucket Transfers

    CERN Document Server

    Ferrand, Thibault; Damerau, Heiko; CERN. Geneva. ATS Department

    2015-01-01

    To reach high particle energies with synchrotrons, a chain of several accelerators is required, as the ratio of extraction and injection energy is in the range of 10 to 20 per synchrotron. Hence the beam must be transfered from one accelerator to the next one. This document deals with the bunch-to-bucket transfer method to inject particle bunches composing the beam from a source synchrotron to a target synchrotron. After we highlight the theoretical concept of the bunch-to-bucket transfer, we determine physical limitations due to the beam dynamics and the adiabatic aspect of the particle bunches. A summary of the currently performed bunch-to-bucket transfer scenarios between the accelerators at CERN is given and set in relation with the mentioned theoretical concepts.

  18. 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...

  19. 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.

  20. Caustic-based approach to understanding bunching dynamics and current spike formation in particle bunches

    Science.gov (United States)

    Charles, T. K.; Paganin, D. M.; Dowd, R. T.

    2016-10-01

    Current modulations, current spikes, and current horns, are observed in a range of accelerator physics applications including strong bunch compression in Free Electron Lasers and linear colliders, trains of microbunching for terahertz radiation, microbunching instability and many others. This paper considers the fundamental mechanism that drives intense current modulations in dispersive regions, beyond the common explanation of nonlinear and higher-order effects. Under certain conditions, neighboring electron trajectories merge to form caustics, and often result in characteristic current spikes. Caustic lines and surfaces are regions of maximum electron density, and are witnessed in accelerator physics as folds in phase space of accelerated bunches. We identify the caustic phenomenon resulting in cusplike current profiles and derive an expression which describes the conditions needed for particle-bunch caustic formation in dispersive regions. The caustic expression not only reveals the conditions necessary for caustics to form but also where in longitudinal space the caustics will form. Particle-tracking simulations are used to verify these findings. We discuss the broader implications of this work including how to utilize the caustic expression for manipulation of the longitudinal phase space to achieve a desired current profile shape.

  1. 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.

  2. Phase detector and phase feedback for a single bunch in a two-bunch damping ring for the SLAC Linear Collider

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, H.D.; Judkins, J.G.

    1987-03-01

    The synchronous phase of a bunch of positrons or electrons being damped in a SLAC Linear Collider (SLC) damping ring is dependent on beam intensity. Injection for alternate bunches into the SLC linac from the damping rings should occur at a constant phase. A phase detector was developed allowing the measurement of phase of a single-stored bunch in the presence of a second bunch in reference to the phase of the linac. The single-bunch phase is derived from beam position monitor signals using a switching scheme to separate the two bunches circulating in each damping ring. The hardware is described including feedback loops to stabilize the extraction phase.

  3. 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

  4. 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.

  5. 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.

  6. The short bunch blow-out regime in RF photoinjectors

    Energy Technology Data Exchange (ETDEWEB)

    Serafini, L. [INFN and Universita di Milano, Via Celoria 16, 20133Milano (Italy)

    1997-06-01

    A new beam dynamics regime of RF Photoinjectors is presented here, dealing with a violent bunch elongation under the action of longitudinal space charge forces. It is shown that such a blow-out expansion of the electron bunch can lead to highly linear behaviors of both the longitudinal and the transverse space charge field, a well known prerequisite to achieve minimum emittance dilution in photoinjectors. If operated in the ultra-short pancake-like bunch regime, such an effect can be very beneficial to the emittance correction mechanism, making it effective also for ultra-short pancake like bunches. The anticipated performances are presented: kA peak current beams can be generated directly out of the photoinjector (10 to 20 MeV exit energy) with rms normalized emittances below 1mm{center_dot}mrad. {copyright} {ital 1997 American Institute of Physics.}

  7. MULTIPLE SINGLE BUNCH EXTRACTION TO THE AGS SWITCHYARD.

    Energy Technology Data Exchange (ETDEWEB)

    BROWN,K.A.; AHRENS,L.; GASSNER,D.; GLENN,J.W.; ROSER,T.; SMITH,G.; TSOUPAS,N.; VAN ASSELT,W.; ZENO,K.

    2001-06-18

    In this report we will describe the multiple single bunch extraction system as utilized to deliver beams to the Brookhaven's Alternating Gradient Synchrotron (AGS) switchyard area. We will describe modifications of the AGS switchyard, necessary to allow it to accept bunched beam, and results of the first commissioning of this system. The AGS Switchyard has for many years been used to simultaneously deliver (unbunched) resonant extracted beam to a set of fixed target experiments. In order to accommodate new fixed target experiments which require bunched beams, a method of sending the bunched beams to the AGS Switchyard was required. In addition, by using the AGS switchyard instead of the upstream section of the Brookhaven's Relativistic Heavy Ion Collider (RHIC) injection line the accelerators can be reconfigured quickly and efficiently for filling RHIC. We will present results of the commissioning of this system, which was done in January 2001.

  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. 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.

  10. Space Charge MitigationWith Longitudinally Hollow Bunches

    CERN Document Server

    Oeftiger, Adrian; Rumolo, Giovanni; CERN. Geneva. ATS Department

    2016-01-01

    Suitably, hollow longitudinal phase space distributions have a flat profile and hence reduce the impact of transverse space charge. Dipolar parametric excitation with the phase loop feedback systems provides such hollow distributions under reproducible conditions. We present a procedure to create hollow bunches during the acceleration ramp of CERN’s PS Booster machine with minimal changes to the operational cycle. The improvements during the injection plateau of the downstream Proton Synchrotron are assessed in comparison to standard parabolic bunches.

  11. 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.

  12. 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.

  13. 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...

  14. 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...

  15. Bunch-by-bunch detection of coherent transverse modes from digitized single-bpm signals in the Tevatron

    CERN Document Server

    Stancari, G; Semenov, A

    2012-01-01

    A system was developed for bunch-by-bunch detection of transverse proton and antiproton coherent oscillations based on the signal from a single beam-position monitor (BPM) located in a region of the ring with large amplitude functions. The signal is digitized over a large number of turns and Fourier-analyzed offline with a dedicated algorithm. To enhance the signal, the beam is excited with band-limited noise for about one second, and this was shown not to significantly affect the circulating beams even at high luminosity. The system is used to measure betatron tunes of individual bunches and to study beam- beam effects. In particular, it is one of the main diagnostic tools in an ongoing study of nonlinear beam-beam compensation studies with Gaussian electron lenses. We present the design and operation of this tool, together with results obtained with proton and antiproton bunches.

  16. 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...

  17. 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...

  18. Destructive interferences results in bosons anti bunching: refining Feynman's argument

    Science.gov (United States)

    Marchewka, Avi; Granot, Er'el

    2014-09-01

    The effect of boson bunching is frequently mentioned and discussed in the literature. This effect is the manifestation of bosons tendency to "travel" in clusters. One of the core arguments for boson bunching was formulated by Feynman in his well-known lecture series and has been frequently used ever since. By comparing the scattering probabilities of two bosons and of two distinguishable particles, he concluded: "We have the result that it is twice as likely to find two identical Bose particles scattered into the same state as you would calculate assuming the particles were different" [R.P. Feynman, R.B. Leighton, M. Sands, The Feynman Lectures on Physics: Quantum mechanics (Addison-Wesley, 1965)]. This argument was rooted in the scientific community (see for example [C. Cohen-Tannoudji, B. Diu, F. Laloë, Quantum Mechanics (John Wiley & Sons, Paris, 1977); W. Pauli, Exclusion Principle and Quantum Mechanics, Nobel Lecture (1946)]), however, while this sentence is completely valid, as is proved in [C. Cohen-Tannoudji, B. Diu, F. Laloë, Quantum Mechanics (John Wiley & Sons, Paris, 1977)], it is not a synonym of bunching. In fact, as it is shown in this paper, wherever one of the wavefunctions has a zero, bosons can anti-bunch and fermions can bunch. It should be stressed that zeros in the wavefunctions are ubiquitous in Quantum Mechanics and therefore the effect should be common. Several scenarios are suggested to witness the effect.

  19. High-gradient plasma-wakefield acceleration with two subpicosecond electron bunches.

    Science.gov (United States)

    Kallos, Efthymios; Katsouleas, Tom; Kimura, Wayne D; Kusche, Karl; Muggli, Patric; Pavlishin, Igor; Pogorelsky, Igor; Stolyarov, Daniil; Yakimenko, Vitaly

    2008-02-22

    A plasma-wakefield experiment is presented where two 60 MeV subpicosecond electron bunches are sent into a plasma produced by a capillary discharge. Both bunches are shorter than the plasma wavelength, and the phase of the second bunch relative to the plasma wave is adjusted by tuning the plasma density. It is shown that the second bunch experiences a 150 MeV/m loaded accelerating gradient in the wakefield driven by the first bunch. This is the first experiment to directly demonstrate high-gradient, controlled acceleration of a short-pulse trailing electron bunch in a high-density plasma.

  20. Improved Bunch Splitting for the 75ns LHC Beam

    CERN Document Server

    Damerau, H

    2011-01-01

    The 75ns variant was added to the PS arsenal of LHC-type beams by adapting the 20MHz cavity used to produce the 25 and 50ns variants to operate at a switchable 13MHz. This permitted splitting from harmonic 14 to 28, but at a cost in adiabaticity compared with the h=2142 splitting of the other two cases. Consequently, a delicate empirical optimization was necessary to bring the 75ns beam inside specification. More recently the speed at which the bunches, once fully distinct, are moved apart has been revisited and further optimization achieved. As a by-product, deliberately degrading the splitting by moving the bunches apart too quickly led to sufficient coherent motion in the resultant bunch pair to permit a voltage calibration of the 13MHz cavity by means of the influence on convergence of the rf voltage input into the iterative algorithm of the Tomoscope [1,2].

  1. 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...

  2. Fast cooling of bunches in compton storage rings*

    CERN Document Server

    Bulyak, E; Zimmermann, F

    2011-01-01

    We propose an enhancement of laser radiative cooling by utilizing laser pulses of small spatial and temporal dimensions, which interact only with a fraction of an electron bunch circulating in a storage ring. We studied the dynamics of such electron bunch when laser photons scatter off the electrons at a collision point placed in a section with nonzero dispersion. In this case of ‘asymmetric cooling’, the stationary energy spread is much smaller than under conditions of regular scattering where the laser spot size is larger than the electron beam; and the synchrotron oscillations are damped faster. Coherent oscillations of large amplitude may be damped within one synchrotron period, so that this method can support the rapid successive injection of many bunches in longitudinal phase space for stacking purposes. Results of extensive simulations are presented for the performance optimization of Compton gamma-ray sources and damping rings.

  3. 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

  4. 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.

  5. 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.)

  6. Development of a bunch-by-bunch longitudinal feedback system with a wide dynamic range for the HIGS facility

    Energy Technology Data Exchange (ETDEWEB)

    Wu, W.Z., E-mail: wwz@fel.duke.ed [Department of Physics, Duke University, Durham, NC 27708-0305 (United States); DFELL, Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Kim, Y. [Department of Physics, Idaho State University, Pocatello, ID 83209-8288 (United States); Li, J.Y. [Department of Physics, Duke University, Durham, NC 27708-0305 (United States); DFELL, Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Teytelman, D. [Dimtel, Inc., San Jose, CA 95124 (United States); Busch, M.; Wang, P.; Swift, G. [Department of Physics, Duke University, Durham, NC 27708-0305 (United States); DFELL, Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Park, I.S.; Ko, I.S. [Pohang Accelerator Laboratory, POSTECH, Pohang 790-784 (Korea, Republic of); Wu, Y.K., E-mail: wu@fel.duke.ed [Department of Physics, Duke University, Durham, NC 27708-0305 (United States); DFELL, Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States)

    2011-03-11

    Electron beam coupled-bunch instabilities can limit and degrade the performance of storage ring based light sources. A longitudinal feedback system has been developed for the Duke storage ring to suppress multi-bunch beam instabilities which prevent stable, high-current operation of the storage ring based free-electron lasers (FELs) and an FEL driven Compton gamma source, the high intensity gamma-ray source (HIGS) at Duke University. In this work, we report the development of a state-of-the-art second generation longitudinal feedback system which employs a field programmable gate array (FPGA) based processor, and a broadband, high shunt-impedance kicker cavity. With two inputs and two outputs, the kicker cavity was designed with a resonant frequency of 937 MHz, a bandwidth of 97 MHz, and a shunt impedance of 1530{Omega}. We also developed an S-matrix based technique to fully characterize the performance of the kicker cavity in the cold test. This longitudinal feedback system has been commissioned and optimized to stabilize high-current electron beams with a wide range of electron beam energies (250 MeV to 1.15 GeV) and a number of electron beam bunch modes, including the single-bunch mode and all possible symmetric bunch modes. This feedback system has become a critical instrument to ensure stable, high-flux operation of HIGS to produce nearly monochromatic, highly polarized Compton gamma-ray beams.

  7. Non-linear effects in bunch compressor of TARLA

    Science.gov (United States)

    Yildiz, Hüseyin; Aksoy, Avni; Arikan, Pervin

    2016-03-01

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

  8. Generation of sub-picosecond electron bunches from RF photoinjectors

    Energy Technology Data Exchange (ETDEWEB)

    Serafini, L. [Istituto Nazionale di Fisica Nucleare, Milan (Italy); Zhang, R. [California Univ., Los Angeles, CA (United States). Dept. of Physics; Pellegrini, C. [California Univ., Los Angeles, CA (United States). Dept. of Physics

    1997-03-11

    In this paper we discuss the possibility to generate sub-picosecond electron bunches directly from a photoinjector by illuminating a photo-cathode in an RF cavity with a phase-locked sub-picosecond laser pulse. In particular, we address all de-bunching effects taking place during acceleration and transport through a photoinjector. We provide analysis of the beam dynamics, as well as the comparison with numerical simulations. The possible performances of the present SATURNUS linac setup are presented, as well as the anticipated capabilities of a multi-cell RF gun structure based on the PWT linac presently in operation at UCLA. (orig.).

  9. 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.

  10. Collective Deceleration of Laser-Driven Electron Bunches

    Science.gov (United States)

    Chou, S.; Xu, J.; Khrennikov, K.; Cardenas, D. E.; Wenz, J.; Heigoldt, M.; Hofmann, L.; Veisz, L.; Karsch, S.

    2016-09-01

    Few-fs electron bunches from laser wakefield acceleration (LWFA) can efficiently drive plasma wakefields (PWFs), as shown by their propagation through underdense plasma in two experiments. A strong and density-insensitive deceleration of the bunches has been observed in 2 mm of 1 018 cm-3 density plasma with 5.1 GV /m average gradient, which is attributed to a self-driven PWF. This observation implies that the physics of PWFs, usually relying on large-scale rf accelerators as drivers, can be studied by tabletop LWFA electron sources.

  11. 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.

  12. Measuring short electron bunch lengths using coherent smith-purcell radiation

    Science.gov (United States)

    Nguyen, Dinh C.

    1999-01-01

    A method is provided for directly determining the length of sub-picosecond electron bunches. A metallic grating is formed with a groove spacing greater than a length expected for the electron bunches. The electron bunches are passed over the metallic grating to generate coherent and incoherent Smith-Purcell radiation. The angular distribution of the coherent Smith-Purcell radiation is then mapped to directly deduce the length of the electron bunches.

  13. Self-modulation instability of ultra-relativistic particle bunches with finite rise times

    CERN Document Server

    Vieira, J; Fang, Y; Mori, W B; Muggli, P; Silva, L O

    2014-01-01

    We study the evolution of the self-modulation instability using bunches with finite rise times. Using particle-in-cell simulations we show that unlike long bunches with sharp rise times, there are large variations of the wake amplitudes and wake phase velocity when bunches with finite rise times are used. These results show that use of bunches with sharp rise times is important to seed the self-modulation instability and to ensure stable acceleration regimes.

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

    OpenAIRE

    Gaupp, Andreas

    2013-01-01

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

  15. Generation of stable ultra-relativistic attosecond electron bunches via the laser wakefield acceleration mechanism

    NARCIS (Netherlands)

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

    2009-01-01

    In recent experiments ultra-relativistic femtosecond electron bunches were generated by a Laser Wakefield Accelerator (LWFA) in different regimes. Here we predict that even attosecond bunches can be generated by an LWFA due to the fast betatron phase mixing within a femtosecond electron bunch. The a

  16. Nonlinear structure of the wakefield generated by relativistic intense ion bunch

    Science.gov (United States)

    Koshelev, A. A.; Andreev, N. E.

    2016-11-01

    The resonant excitation of the nonlinear wakefield by a single proton bunch is investigated with the parameters characteristic of the AWAKE experiment. It is shown that obtained structure of the wakefield at a distance more than twenty periods behind the driver proton bunch can be suitable for the side injection and further acceleration of the witness electron bunch in the wakefield.

  17. 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.

  18. 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.

  19. 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.

  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. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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...

  6. 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.)

  7. Loss Factor of Tapered Structures for Short Bunches

    Energy Technology Data Exchange (ETDEWEB)

    Blednykh, A.

    2011-03-28

    Using the electromagnetic simulation code ECHO, we have found a simple phenomenological formula that accurately describes the loss factor for short bunches traversing an axisymmetric tapered collimator. In this paper, we consider tapered collimators with rectangular cross-section and use the GdfidL code to calculate the loss factor dependence on the geometric parameters for short bunches. The results for both axisymmetric and rectangular collimators are discussed. The behaviour of the impedance of tapered structures for very short bunches in the optical regime has been determined in refs. [10,11]. Here, for the loss factors for two particular geometries, we have studied the departure from the optical regime behaviour as bunch length is increased. In both cases, the ratio of the loss factor for the tapered collimator to the loss factor in the optical regime is a function only of the scaling parameter {sigma}L/d{sup 2}. The fact that the bunch length a and the taper length L appear as a product is consistent with the recent scaling derived by Stupakov in ref. [12], since there is only a weak dependence on g. One noteworthy fact that is not a priori expected is that only the larger radius or vertical half-aperture d appears. The reduction factor is independent of b. Moreover, it is striking that the specific form involving the arctan given in Eq. (5) holds for both geometries, with only the coefficient {mu} differing by a factor of {approx}2 for flat vs round. This suggests that there may be a useful phenomenological form for more general geometries which may follow from natural extensions of Eq. (5). This possibility is presently being investigated.

  8. 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.

  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. Influence of emittance on transverse dynamics of accelerated bunches in the plasma–dielectric wakefield accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Kniaziev, R.R., E-mail: rkniaziev@gmail.com [V.N. Karazin Kharkov National University, Kharkov (Ukraine); NSC Kharkov Institute of Physics and Technology, Kharkov (Ukraine); Sotnikov, G.V. [NSC Kharkov Institute of Physics and Technology, Kharkov (Ukraine)

    2016-09-01

    We study theoretically transverse dynamics of the bunch of charged particles with the finite emittance in the plasma–dielectric wakefield accelerator. Parameters of bunches are chosen the same as available from the 15 MeV Argonne Wakefield Accelerator beamline. The goal of the paper is to study the behavior of bunches of charged particles with different emittances while accelerating these bunches by wakefields in plasma–dielectric structures. Obtained results allow us to determine the limits of the emittance of the bunch where dynamics of the accelerated particles remains stable.

  11. 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.

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

    CERN Document Server

    Damerau, H

    2005-01-01

    To maximize the luminosity of the Large Hadron Collider (LHC), the collision of particle bunches with a uniform longitudinal particle density is considered for a future upgrade. The benefits of such bunches and their generation by means of special longitudinal beam manipulations are presented in this report. Three possible options are analyzed with respect to their potential luminosity gain at the beam-beam limit: short rectangular bunches held by radio frequency (RF) harmonics using multiples of the nominal RF frequency of 400.8MHz, long and flat bunches held by multiples of 40.08MHz, and so-called superbunches, confined by barrier buckets. The comparison of the three different approaches shows that flat bunches, with an intermediate bunch length of the order of several meters, are capable of producing a comparable luminosity to superbunches, while avoiding most of their inherent disadvantages. Possible schemes to create the bunches with uniform line density are studied and a longitudinal manipulation to com...

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

    Energy Technology Data Exchange (ETDEWEB)

    Kirby, Neil; /SLAC

    2009-10-30

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

  14. 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.

  15. Study of the heavy ion bunch compression in CSRm

    Institute of Scientific and Technical Information of China (English)

    YIN Da-Yu; LIU Yong; YUAN You-Jing; YANG Jian-Cheng; LI Peng; LI Jie; CHAI Wei-Ping

    2013-01-01

    The feasibility of attaining nanosecond pulse length heavy ion beam is studied in the main ring (CSRm)of the Heavy Ion Research Facility in Lanzhou.Such heavy ion beam can be produced by non-adiabatic compression,and it is implemented by a fast rotation in the longitudinal phase space.In this paper,the possible beam parameters during longitudinal bunch compression are studied with the envelope model and Particle in Cell simulation,and the results are compared.The result shows that the short bunch 238U28+ with the pulse duration of about 50 ns at the energy of 200 MeV/u can be obtained which can satisfy the research of high density plasma physics experiment.

  16. Bunch compression study using the envelope model in CSRm

    Institute of Scientific and Technical Information of China (English)

    YIN Da-Yu; LIU Yong; YUAN You-Jin; YANG Jian-Cheng; LI Peng; MEI Li-Rong; CHAI Wei-Ping; ZHANG Xiao-Hu

    2012-01-01

    The feasibility of attaining a short-pulse-duration heavy ion beam with a nanosecond pulse length is studied in the main ring of the Heavy Ion Research Facility in Lanzhou (HIRFL).Such a heavy ion beam can be produced by non-adiabatic compression,and it is implemented by fast rotation in the longitudinal phase space.In this paper,the possible beam parameters during longitudinal bunch compression are studied by using the envelope model.The result shows that a shortest heavy ion bunch 238U28+ of 29 ns with energy of 200 MeV/u can be obtained,which can satisfy high energy density physics research.

  17. 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.

  18. 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.

  19. Emittance preservation during bunch compression with a magnetized beam

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. 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.

  1. 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.

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

    Science.gov (United States)

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

    2016-04-01

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

  3. Higher-order photon bunching in a semiconductor microcavity

    DEFF Research Database (Denmark)

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

    2009-01-01

    Quantum mechanically indistinguishable particles such as photons may show collective behavior. Therefore, an appropriate description of a light field must consider the properties of an assembly of photons instead of independent particles. We have studied multiphoton correlations up to fourth order...... 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...... in the strong coupling case, which vanishes in the weak coupling regime as the cavity starts lasing. In particular, we verify the n factorial prediction for the zero-delay correlation function of n thermal light photons....

  4. 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.

  5. Coupled-bunch instabilities due to fundamental cavity impedance

    CERN Document Server

    Mastoridis, Themistoklis; Chapochnikova, Elena; Esteban Muller, Juan; Molendijk, John; Timko, Helga; CERN. Geneva. ATS Department

    2017-01-01

    The purpose of this MD was to estimate the stability threshold due to longitudinal coupled-bunch instabilities (CBIs) driven by the RF cavities' fundamental impedance. These instabilities are not a concern for the LHC. A model was developed to study the stability threshold for the High-Luminosity LHC (HL-LHC). The goal of this MD was to validate this model and thus its predictions for the HL-LHC stability margins.

  6. Predicting fresh fruit bunch yield of oil palm

    Directory of Open Access Journals (Sweden)

    Nilnond, C.

    2001-11-01

    Full Text Available This study aimed to develop the simulation model for predicting fresh fruit bunch (FFB yield of oil palm through multiple linear regression analysis. Two experiments were conducted at the oil palm plantation of Agricultural and Technology College, Krabi province. Six-year-old Tenera hybrid palms were used for the experiments. These palms were planted in Tha-sae soil series (Typic Paleudults; Fine loamy mixedwith spacing of 9x9x9 m. In the first experiment, 151 Tenera palms were selected and marked randomly throughout an area of plantation about 16 ha. For each selected palm, FFB yield and yield component characters (FFB number and bunch weight were recorded at every harvesting time for four consecutive years (June 1993 to May 1997. The results showed that the FFB number and bunch weight could be used to predict the FFB oil palm yield. In the second experiment, nine plots of Tenera hybrid palms were arranged. The plot size was 0.48 ha and had twenty palms per plot for data collection for three consecutive years (January 1994 to December 1996. These data included leaf nutrient (N, P, K, Mg and B contents in the 17th frond, the fresh fruit bunch (FFB yield and the amount of rainfall. The results showed that N, P, K, Mg and B contents in the leaves, the amount of rainfall and FFB yield in the previous year, together with the N, P, K, Mg and B contents in the leaves (in the predicting year could be used to predict the FFB oil palm yield.

  7. 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.

  8. 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)

  9. 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.

  10. 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...

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

    Energy Technology Data Exchange (ETDEWEB)

    Uesaka, Mitsuru (Nuclear Engineering Research Laboratory, University of Tokyo, 2-22 Shirakata-Shirane, Tokai-mura, Naka-gun, Ibaraki 319-11 (Japan)); Kozawa, Takahiro (Nuclear Engineering Research Laboratory, University of Tokyo, 2-22 Shirakata-Shirane, Tokai-mura, Naka-gun, Ibaraki 319-11 (Japan)); Kobayashi, Toshiaki (Nuclear Engineering Research Laboratory, University of Tokyo, 2-22 Shirakata-Shirane, Tokai-mura, Naka-gun, Ibaraki 319-11 (Japan)); Ueda, Toru (Nuclear Engineering Research Laboratory, University of Tokyo, 2-22 Shirakata-Shirane, Tokai-mura, Naka-gun, Ibaraki 319-11 (Japan)); Miya, Kenzo (Nuclear Engineering Research Laboratory, University of Tokyo, 2-22 Shirakata-Shirane, Tokai-mura, Naka-gun, Ibaraki 319-11 (Japan))

    1994-06-15

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Damerau, H.

    2005-09-01

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

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

    CERN Document Server

    Young, A

    2001-01-01

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

  14. LHC MD 652: Coupled-Bunch Instability with Smaller Emittance (all HOMs)

    CERN Document Server

    Esteban Muller, Juan; Timko, Helga; CERN. Geneva. ATS Department

    2017-01-01

    The aim of the MD was to measure the coupled-bunch stability from all HOM impedances, with a reduced longitudinal emittance in order to explore the HL-LHC conditions. The acceleration ramp was performed with the nominal beams of 2016, but a reduced target bunch length and RF voltage. With this reduced emittance, the beam remained close but above the single-bunch stability threshold. No coupled-bunch oscillations were observed, so we can conclude that the stability threshold for coupled-bunch instability is not lower than the single-bunch threshold. An interesting observation in the MD was the long-lasting injection oscillations, whose traces can still be seen at arrival to flat top; in agreement with observations in earlier MDs. The measurements took place between 28th October 20:00 and 29th October 05:10.

  15. 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...

  16. 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.

  17. Temporal evolution of longitudinal bunch profile in a laser wakefield accelerator

    OpenAIRE

    Heigoldt, M; Popp, A; Khrennikov, K.; Wenz, J; Chou, SW; Karsch, S.; Bajlekov, SI; Hooker, SM; Schmidt, B.

    2015-01-01

    © 2015 authors. Published by the American Physical Society. We present single-shot measurements of the longitudinal bunch profile from a laser-wakefield accelerator with sub-fs resolution, based on detection of coherent transition radiation in a broad spectral range. A previously developed phase retrieval algorithm enables reconstruction of the bunch profile without prior assumptions about its shape. In this study, a variable-length gas target is used to explore the dynamics of bunch evolutio...

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

    OpenAIRE

    Li, Weiwei; He, Zhiagng; Jia, Qika

    2013-01-01

    We consider a scheme to generate 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 bunc...

  19. 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.

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

    CERN Document Server

    Li, Weiwei; Jia, Qika

    2013-01-01

    We consider a scheme to generate 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.

  1. Conceptual design and modeling of a six-dimensional bunch merging scheme for a muon collider

    Science.gov (United States)

    Bao, Yu; Hanson, Gail; Palmer, Robert B.; Stratakis, Diktys

    2016-03-01

    A high luminosity muon collider requires single, intense, muon bunches with small emittances: just one of each sign. An efficient front end and a cooling channel have been designed and simulated within the collaboration of the Muon Accelerator Program. The muons are first bunched and phase rotated into 21 bunches, and then cooled in six dimensions. When they are cool enough, they are merged into single bunches: one of each sign. The bunch merging scheme has been outlined with preliminary simulations in previous studies. In this paper we present a comprehensive design with its end-to-end simulation. The 21 bunches are first merged in longitudinal phase space into seven bunches. These are directed into seven "trombone" paths with different lengths, to bring them to the same time, and then merged transversely in a collecting "funnel" into the required single larger bunches. Detailed numerical simulations show that the 6D emittance of the resulting bunch reaches the parameters needed for high acceptance into the downstream cooling channel.

  2. Effects of the precursor electron bunch on quasi-phase matched direct laser acceleration

    Science.gov (United States)

    Lin, M.-W.; Hsieh, C.-Y.; Liu, Y.-L.; Chen, S.-H.; Jovanovic, I.

    2016-12-01

    Direct laser acceleration (DLA) of electrons can be achieved by utilizing the axial field of a well-guided, radially polarized laser pulse in a density-modulated plasma waveguide. When a laser pulse of a few terawatt (TW) peak power is applied, however, the laser ponderomotive force perturbs plasma electrons to concentrate in the center, such that the generated electrostatic fields can significantly defocus the externally injected electron witness bunch and considerably deteriorate the acceleration efficiency. To improve the performance of DLA, a leading electron bunch, which acts as a precursor, can be introduced in DLA to effectively confine the witness bunch. Three-dimensional particle-in-cell simulations have been conducted to demonstrate that the transverse properties of the witness bunch can be significantly improved when a precursor bunch is used. Selected bunch transverse sizes, bunch charges, and axial separation from the witness bunch have been assigned to the precursor in a series of DLA simulations. Since a favorable ion-focusing force is provided by the precursor, the transverse properties of witness bunch can be maintained when a relatively high-power (˜2 TW) laser pulse is used in DLA, and an improved overall acceleration efficiency can be achieved.

  3. Density of bunches of native bluebunch wheatgrass and alien crested wheatgrass

    Energy Technology Data Exchange (ETDEWEB)

    Rickard, W.H.

    1985-10-01

    The density of bunches of bluebunch wheatgrass in a natural undisturbed stand averaged 3.28 per m/sup 2/ as compared to 2.96 per m/sup 2/ for a nearby stand of crested wheatgrass that was planted 30 years ago. Bunch density was similar in both stands indicating that spacing is a response to an environment deficient in soil water. Bunches of crested wheatgrass on the average weighed 3.5 times more than bunches of bluebunch wheatgrass and they also produced a greater weight of seedheads.

  4. 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)

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. Wave Localization and Density Bunching in Pair Ion Plasmas

    CERN Document Server

    Mahajan, Swadesh M

    2008-01-01

    By investigating the nonlinear propagation of high intensity electromagnetic (EM) waves in a pair ion plasma, whose symmetry is broken via contamination by a small fraction of high mass immobile ions, it is shown that this new and interesting state of (laboratory created) matter is capable of supporting structures that strongly localize and bunch the EM radiation with density excess in the region of localization. Testing of this prediction in controlled laboratory experiments can lend credence, inter alia, to conjectures on structure formation (via the same mechanism) in the MEV era of the early universe.

  10. 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.

  11. 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.

  12. Simulation of 6 to 3 to 1 merge and squeeze of Au77+ bunches in AGS

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-09

    In order to increase the intensity per Au77+ bunch at AGS extraction, a 6 to 3 to 1 merge scheme was developed and implemented by K. Zeno during the 2016 RHIC run [1]. For this scheme, 12 Booster loads, each consisting of a single bunch, are delivered to AGS per AGS magnetic cycle. The bunch from Booster is itself the result of a 4 to 2 to 1 merge which is carried out on a at porch during the Booster magnetic cycle [2]. Each Booster bunch is injected into a harmonic 24 bucket on the AGS injection porch. In order to t into the buckets and allow for the AGS injection kicker rise time, the bunch width must be reduced by exciting quadrupole oscillations just before extraction from Booster [1]. The bunches are injected into two groups of six adjacent harmonic 24 buckets. In each group the 6 bunches are merged into 3 by bringing on RF harmonic 12 while reducing harmonic 24. This is a straightforward 2 to 1 merge (in which two adjacent bunches are merged into one). One ends up with two groups of three adjacent bunches sitting in harmonic 12 buckets. These bunches are accelerated to an intermediate porch for further merging. Doing the merge on a porch that sits above injection energy helps reduce losses that are believed to be due to the space-charge force acting on the bunched particles [3]. (The 6 to 3 merge is done on the injection porch because the harmonic 24 frequency on the intermediate porch would be too high for the AGS RF cavities.) On the intermediate porch each group of 3 bunches is merged into one by bringing on RF harmonics 8 and 4 and then reducing harmonics 12 and 8. One ends up with 2 bunches, each the result of a 6 to 3 to 1 merge and each sitting in a harmonic 4 bucket. This puts 6 Booster loads into each bunch. Each merged bunch needs to be squeezed into a harmonic 12 bucket for subsequent acceleration. This is done by again bringing on harmonic 8 and then harmonic 12.

  13. Advanced simulation study on bunch gap transient effect

    Science.gov (United States)

    Kobayashi, Tetsuya; Akai, Kazunori

    2016-06-01

    Bunch phase shift along the train due to a bunch gap transient is a concern in high-current colliders. In KEKB operation, the measured phase shift along the train agreed well with a simulation and a simple analytical form in most part of the train. However, a rapid phase change was observed at the leading part of the train, which was not predicted by the simulation or by the analytical form. In order to understand the cause of this observation, we have developed an advanced simulation, which treats the transient loading in each of the cavities of the three-cavity system of the accelerator resonantly coupled with energy storage (ARES) instead of the equivalent single cavities used in the previous simulation, operating in the accelerating mode. In this paper, we show that the new simulation reproduces the observation, and clarify that the rapid phase change at the leading part of the train is caused by a transient loading in the three-cavity system of ARES. KEKB is being upgraded to SuperKEKB, which is aiming at 40 times higher luminosity than KEKB. The gap transient in SuperKEKB is investigated using the new simulation, and the result shows that the rapid phase change at the leading part of the train is much larger due to higher beam currents. We will also present measures to mitigate possible luminosity reduction or beam performance deterioration due to the rapid phase change caused by the gap transient.

  14. 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.

  15. 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 ...

  16. 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.

  17. 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.

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

    Science.gov (United States)

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

    2016-04-01

    We have built, operated, and characterized a compact ion source for low-energy bunches of singly charged atomic ions in a vacuum beam line. It is based on atomic evaporation from an electrically heated oven and ionization by electron impact from a heated filament inside a grid-based ionization volume. An adjacent electrode arrangement is used for ion extraction and focusing by applying positive high-voltage pulses to the grid. The method is particularly suited for experimental environments which require low electromagnetic noise. It has proven simple yet reliable and has been used to produce μs-bunches of up to 10(6) Mg(+) ions at a repetition rate of 1 Hz. We present the concept, setup and characterizing measurements. The instrument has been operated in the framework of the SpecTrap experiment at the HITRAP facility at GSI/FAIR to provide Mg(+) ions for sympathetic cooling of highly charged ions by laser-cooled (24)Mg(+).

  19. 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.

  20. Methods of computer processing of experimental data on the intensity of bunches in synchrotrons

    Science.gov (United States)

    Zhabitsky, V. M.

    2016-12-01

    Methods of computer processing of experimental data on the intensity of bunches in synchrotrons for the purpose of receiving functional dependences from time during the accelerating cycle for a number of circulating particles and the mean-square length of a bunch are discussed. Examples of such dependences for the beam at the nuclotron (JINR) and PSB (CERN) are presented.

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

    CERN Document Server

    Burov, Alexey

    2016-01-01

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

  2. 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

  3. Matching into the Helical Bunch Coalescing Channel for a High Luminosity Muon Collider

    Energy Technology Data Exchange (ETDEWEB)

    Sy, Amy [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Ankenbrandt, Charles [Muons Inc., Batavia, IL (United States); Derbenev, Yaroslav [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Morozov, Vasiliy [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Neuffer, David [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Yonehara, Katsuya [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Yoshikawa, Cary [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Johnson, R. P. [Muons Inc., Batavia, IL (United States)

    2015-09-01

    For high luminosity in a muon collider, muon bunches that have been cooled in the six-dimensional helical cooling channel (HCC) must be merged into a single bunch and further cooled in preparation for acceleration and transport to the collider ring. The helical bunch coalescing channel has been previously simulated and provides the most natural match from helical upstream and downstream subsystems. This work focuses on the matching from the exit of the multiple bunch HCC into the start of the helical bunch coalescing channel. The simulated helical matching section simultaneously matches the helical spatial period lambda in addition to providing the necessary acceleration for efficient bunch coalescing. Previous studies assumed that the acceleration of muon bunches from p=209.15 MeV/c to 286.816 MeV/c and matching of lambda from 0.5 m to 1.0 m could be accomplished with zero particle losses and zero emittance growth in the individual bunches. This study demonstrates nonzero values for both particle loss and emittance growth, and provides considerations for reducing these adverse effects to best preserve high luminosity.

  4. A Value-Engaged Approach for Evaluating the Bunche-Da Vinci Learning Academy

    Science.gov (United States)

    Greene, Jennifer C.

    2005-01-01

    In 2001, the Bunche Academy was chosen by its district to join in partnership with the Da Vinci Learning Corporation to embark on an ambitious whole-school reform initiative, especially designed by the corporation for low-performing schools. In this chapter, the author describes how, as illustrated in the Bunche-Da Vinci Learning Academy context,…

  5. A Proposal to Build Evaluation Capacity at the Bunche-Da Vinci Learning Partnership Academy

    Science.gov (United States)

    King, Jean A.

    2005-01-01

    The author describes potential evaluation capacity-building activities in contrast to the specifics of an evaluation design. Her response to the case of the Bunche-Da Vinci Learning Partnership Academy is developed in three parts: (1) an initial framing of the Bunche-Da Vinci situation; (2) what should be done before signing a contract; and (3)…

  6. Single/Few Bunch Space Charge Effects at 8 GeV in the Fermilab Main Injector

    Energy Technology Data Exchange (ETDEWEB)

    Scott, D.J.; Capista, D.; Kourbanis, I.; Seiya, K.; Yang, M.-J.; /Fermilab

    2012-05-01

    For Project X, it is planned to inject a beam of 3 10{sup 11} particles per bunch into the Main Injector. Therefore, at 8 GeV, there will be increased space charge tune shifts and an increased incoherent tune spread. In preparation for these higher intensity bunches exploratory studies have commenced looking at the transmission of different intensity bunches at different tunes. An experiment is described with results for bunch intensities between 20 and 300 10{sup 9} particles. To achieve the highest intensity bunches coalescing at 8 GeV is required, resulting in a longer bunch length. Comparisons show that similar transmission curves are obtained when the intensity and bunch length have increased by similar factors. This indicates the incoherent tune shifts are similar, as expected from theory. The results of these experiments will be used in conjugation with simulations to further study high intensity bunches in the Main Injector.

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

    CERN Document Server

    Balbekov, V

    2015-01-01

    Transverse instability of a bunch in a circular accelerator is elaborated in this paper. New tree-modes model is proposed and developed to describe the most unstable modes of the bunch. The model includes chromaticity and space charge, and can be used with any bunch and wake forms. Dispersion relation for the bunch eigentunes is obtained in form of a third-order algebraic equation. Known head-tail and TMCI modes appear as the ultimate cases which are distinctly bounded at zero chromaticity only. It is shown that the instability parameters depend only slightly on the bunch model but are rather sensitive to the wake shape. Resistive wall wake is considered in detail including a comparison of single and collective effects. It is shown that space charge influence depends on sign of the wake function enhancing the stability with negative one.

  8. Longitudinal electron bunch diagnostics using coherent transition radiation at the IRFEL

    Science.gov (United States)

    Zhou, T. Y.; Yang, Y. L.; Sun, B. G.; Tang, L. L.; Lu, P.; Zhou, Z. R.; Wu, F. F.; Liu, X. Y.

    2016-09-01

    A longitudinal electron bunch diagnostics system is developing to measure the longitudinal bunch charge distribution for the new IRFEL at National Synchrotron Radiation Laboratory (NSRL). We use a Martin-Puplett interferometer, which is essentially a Michelson interferometer, to measure the spectrum of the coherent transition radiation produced by electrons through a thin metallic foil. Frequency components of coherent transition radiation have a relationship with the bunch form factor, which is described by the square modulus of the Fourier transform of the bunch distribution. Then several techniques, including a Kramers-Kronig analysis, have been applied to determine the longitudinal bunch charge distribution. The details of the design and theoretical investigation will be described in this paper.

  9. Bunch compression efficiency of the femtosecond electron source at Chiang Mai University

    Energy Technology Data Exchange (ETDEWEB)

    Thongbai, C. [Department of Physics and Materials Science, Chiang Mai University, Chiangmai 50200 (Thailand); ThEP Center, Commission on Higher Education, Ministry of Education, Bangkok 10400 (Thailand); Kusoljariyakul, K., E-mail: zartparz@gmail.com [Department of Physics and Materials Science, Chiang Mai University, Chiangmai 50200 (Thailand); ThEP Center, Commission on Higher Education, Ministry of Education, Bangkok 10400 (Thailand); Saisut, J. [Department of Physics and Materials Science, Chiang Mai University, Chiangmai 50200 (Thailand); ThEP Center, Commission on Higher Education, Ministry of Education, Bangkok 10400 (Thailand)

    2011-07-21

    A femtosecond electron source has been developed at the Plasma and Beam Physics Research Facility (PBP), Chiang Mai University (CMU), Thailand. Ultra-short electron bunches can be produced with a bunch compression system consisting of a thermionic cathode RF-gun, an alpha-magnet as a magnetic bunch compressor, and a linear accelerator as a post acceleration section. To obtain effective bunch compression, it is crucial to provide a proper longitudinal phase-space distribution at the gun exit matched to the subsequent beam transport system. Via beam dynamics calculations and experiments, we investigate the bunch compression efficiency for various RF-gun fields. The particle distribution at the RF-gun exit will be tracked numerically through the alpha-magnet and beam transport. Details of the study and results leading to an optimum condition for our system will be presented.

  10. Thermal damage at short electron bunches passage through a thin target

    Science.gov (United States)

    Babaev, A. A.; Gogolev, A. S.

    2016-07-01

    The thin target could be used for beam diagnostics by means the radiation that is induced by interaction of beam particles with target matter. The electron beams used in modern applications (as, for example, modern FELs) have very large brightness, small emittance as well as very short bunch length. For example, the bunch length of XFEL is about of 25 um at bunch charge order of 1 nC and with electrons energy of 17.5 GeV. The passage of this powerful short bunches could damage the target or even completely destroy it. In the presented work the train of such bunches passages through the target is investigated. It is shown the target works in extreme regime close to phase transition temperature.

  11. Dynamics of electron bunches at the laser–plasma interaction in the bubble regime

    Energy Technology Data Exchange (ETDEWEB)

    Maslov, V.I., E-mail: vmaslov@kipt.kharkov.ua; Svystun, O.M., E-mail: svistun_elena@mail.ru; 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.

  12. 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.

  13. 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.

  14. Transverse dynamics of an intense electron bunch traveling through a pre-ionized plasma

    Energy Technology Data Exchange (ETDEWEB)

    Lehe, R., E-mail: remi.lehe@ensta.fr; Thaury, C.; Lifschitz, A.; Rax, J.-M.; Malka, V. [Laboratoire d' Optique Appliquée, ENSTA-CNRS-Ecole Polytechnique, UMR 7639, 91761 Palaiseau (France)

    2014-04-15

    The propagation of a relativistic electron bunch through a plasma is an important problem in both plasma-wakefield acceleration and laser-wakefield acceleration. In those situations, the charge of the accelerated bunch is usually large enough to drive a relativistic wakefield, which then affects the transverse dynamics of the bunch itself. Yet to date, there is no fully relativistic, fully electromagnetic model that describes the generation of this wakefield and its feedback on the bunch. In this article, we derive a model which takes into account all the relevant relativistic and electromagnetic effects involved in the problem. A very good agreement is found between the model and the results of particle-in-cell simulations. The implications of high-charge effects for the transport of the bunch are discussed in detail.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2001-06-18

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

  16. 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.

  17. Few femtosecond level electron bunch diagnostic at quasi-cw electron accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Green, Bertram; Kuntzsch, Michael; Kovalev, Sergei; Hauser, Jens; Findeisen, Stefan; Schneider, Christian; Kaya, Caglar; Michel, Peter; Gensch, Michael [Helmholtz-Zentrum Dresden-Rossendorf (Germany); Al-Shemmary, Alaa; Stojanovic, Nikola [Deutsches Elektronen-Synchrotron (Germany)

    2013-07-01

    At the SRF based prototype cw accelerator ELBE a new electron beamline, providing for femtosecond electron bunches with nC bunch charges and repetition rates in the 1-200 KHz regime and with pC bunch charge and repetition rates of 13 MHz, is currently being constructed. The 40 MeV electrons will be used in photon-electron interaction experiments with TW and PW class lasers and the generation of broad and narrow bandwidth coherent THz pulses. Discussed here are ideas for novel online diagnostics of the electron bunch properties (e.g. arrival time and bunch form) based on the time and frequency domain analysis of the emitted coherent THz radiation, but also based on direct measurements by e.g. electro-optic sampling. The suitability of ELBE as a testbed for diagnostic of future cw X-ray photon sources (e.g. energy recovery linacs) will be discussed.

  18. 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.

  19. Tunable subpicosecond electron-bunch-train generation using a transverse-to-longitudinal phase-space exchange technique.

    Science.gov (United States)

    Sun, Y-E; Piot, P; Johnson, A; Lumpkin, A H; Maxwell, T J; Ruan, J; Thurman-Keup, R

    2010-12-03

    We report on the experimental generation of a train of subpicosecond electron bunches. The bunch train generation is accomplished using a beam line capable of exchanging the coordinates between the horizontal and longitudinal degrees of freedom. An initial beam consisting of a set of horizontally separated beamlets is converted into a train of bunches temporally separated with tunable bunch duration and separation. The experiment reported in this Letter unambiguously demonstrates the conversion process and its versatility.

  20. Direct observation of beam bunching in BWO experiments

    CERN Document Server

    Morimoto, I; Maebara, S; Kishiro, J; Takayama, K; Horioka, K; Ishizuka, H; Kawasaki, S; Shiho, M

    2001-01-01

    Backward Wave Oscillation (BWO) experiments using a Large current Accelerator-1 (Lax-1) Induction Linac as a seed power source for an mm-wave FEL are under way. The Lax-1 is typically operated with a 1 MeV electron beam, a few kA of beam current, and a pulse length of 100 ns. In the BWO experiments, annular and solid beams are injected into a corrugated wave guide with guiding axial magnetic field of 1 T. In the BWO with annular beam an output power of 210 MW at 9.8 GHz was obtained. With a solid beam the output power was 130 MW, and an electron beam bunching with the frequency of 9.6-10.2 GHz was observed by a streak camera.

  1. Helical bunching and symmetry lowering inducing multiferroicity in Fe langasites

    Science.gov (United States)

    Chaix, L.; Ballou, R.; Cano, A.; Petit, S.; de Brion, S.; Ollivier, J.; Regnault, L.-P.; Ressouche, E.; Constable, E.; Colin, C. V.; Zorko, A.; Scagnoli, V.; Balay, J.; Lejay, P.; Simonet, V.

    2016-06-01

    The chiral Fe-based langasites represent model systems of triangle-based frustrated magnets with a strong potential for multiferroicity. We report neutron-scattering measurements for the multichiral Ba3M Fe3Si2O14 (M =Nb ,Ta ) langasites revealing new important features of the magnetic order of these systems: the bunching of the helical modulation along the c axis and the in-plane distortion of the 120∘ Fe-spin arrangement. We discuss these subtle features in terms of the microscopic spin Hamiltonian and provide the link to the magnetically induced electric polarization observed in these systems. Thus, our findings put the multiferroicity of this attractive family of materials on solid ground.

  2. 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.

  3. Early transverse decoherence of bunches with space charge

    Science.gov (United States)

    Karpov, Ivan; Kornilov, Vladimir; Boine-Frankenheim, Oliver

    2016-12-01

    The transverse decoherence of injected bunches is an important phenomenon in synchrotrons and storage rings. The initial stage of this process determines the transverse emittance blowup, which should be taken into account for the design of feedback systems, for example. The interplay of different high-intensity effects can strongly affect the initial decoherence stage. We present a model that explains decoherence and emittance growth with chromaticity, space charge, and image charges within the first synchrotron period. We compare the model for different combinations of parameters with self-consistent particle tracking simulations and measurements in the SIS18 synchrotron at GSI Darmstadt. Generally, space charge slows down the decoherence process and can cause the loss of decoherence. Chromaticity and image charges can partly compensate this loss and restore the decoherence. We also analyze the single-particle excitation driven by space charge during the decoherence process. Particles gain large amplitudes from the coherent beam oscillation, which leads to halo buildup and losses.

  4. Can YAG screen accept LEReC bunch train?

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-18

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

  5. 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.

  6. Bunching and cooling of radioactive ions with REXTRAP

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, P. E-mail: k.schmidt@gsi.de; Ames, F.; Bollen, G.; Forstner, O.; Huber, G.; Oinonen, M.; Zimmer, J

    2002-04-22

    The post-accelerator REX-ISOLDE at ISOLDE/CERN will deliver radioactive ion beams with energies up to 2.2 MeV/u. For this purpose, a Penning trap and an electron-beam ion source are combined with a linear accelerator. REXTRAP - a large gas-filled Penning trap - has started its commissioning phase. First tests have shown that REXTRAP is able to accumulate, cool and bunch stable ISOLDE ion beams covering a large mass range. Fulfilling the REX-ISOLDE demands, it can handle beam intensities from a few hundred up to 1x10{sup 6} ions per pulse at repetition rates up to 50 Hz.0.

  7. Radiation of charge bunches revolving around a metamaterial sphere

    Science.gov (United States)

    Torabi, Mahmoud; Shokri, Babak

    2017-01-01

    We investigate the interaction of a relativistic uniformly rotating charge with a metamaterial sphere in the microwave range. The charge revolves around the sphere at the equatorial plane. The root mean square of the radiation field for different types of metamaterial spheres is presented and its dependence on some usual parameters is considered. They demonstrate that the radiation field is concentrated near the surface and shifts towards the centre by increasing charge energy for conventional and double-negative metamaterials. The stopping and deflection forces acting on the charge are also calculated. Finally, we generalize these results to a line charge bunch. This study has potential application in the area of high-power radiation sources and accelerators.

  8. Hydrothermal pretreatment of palm oil empty fruit bunch

    Science.gov (United States)

    Simanungkalit, Sabar Pangihutan; Mansur, Dieni; Nurhakim, Boby; Agustin, Astrid; Rinaldi, Nino; Muryanto, Fitriady, Muhammad Ariffudin

    2017-01-01

    Hydrothermal pretreatment methods in 2nd generation bioethanol production more profitable to be developed, since the conventional pretreatment, by using acids or alkalis, is associated with the serious economic and environmental constraints. The current studies investigate hydrothermal pretreatment of palm oil empty fruit bunch (EFB) in a batch tube reactor system with temperature and time range from 160 to 240 C and 15 to 30 min, respectively. The EFB were grinded and separated into 3 different particles sizes i.e. 10 mesh, 18 mesh and 40 mesh, prior to hydrothermal pretreatment. Solid yield and pH of the treated EFB slurries changed over treatment severities. The chemical composition of EFB was greatly affected by the hydrothermal pretreatment especially hemicellulose which decreased at higher severity factor as determined by HPLC. Both partial removal of hemicellulose and migration of lignin during hydrothermal pretreatment caused negatively affect for enzymatic hydrolysis. This studies provided important factors for maximizing hydrothermal pretreatment of EFB.

  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. 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.

  11. 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.)

  12. 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.

  13. 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.

  14. 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.

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

    Science.gov (United States)

    Garg, Akash Deep; Nathwani, R. K.; Holikatti, A. C.; Kumar Karnewar, Akhilesh; Tyagi, Y.; Yadav, S.; Puntambekar, T. A.; Navathe, C. P.

    2012-11-01

    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.

  16. 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.

  17. 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...

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Experimental investigation of the longitudinal beam dynamics in a photoinjector using a two-macroparticle bunch

    Energy Technology Data Exchange (ETDEWEB)

    Piot, P.; /Northern Illinois U. /Fermilab; Tikhoplav, R.; /Rochester U.; Mihalcea, D.; Barov, N.; /Northern Illinois U.

    2006-03-01

    We have developed a two-macroparticle bunch to explore the longitudinal beam dynamics through various components of the Fermilab/NICADD photoinjector. Such a two-macroparticle bunch is generated by splitting the ultraviolet pulse from the photocathode drive laser. The presented method allows the exploration of radiofrequency-induced compression in the 1.625 cell rf-gun and the booster cavity. It also allows a direct measurement of the momentum compaction of the magnetic bunch compressor. The measurements are compared with analytical and numerical models.

  4. ElectroOptical measurements of ultrashort 45 MeV electron beam bunch

    CERN Document Server

    Nikas, D; Kowalski, L A; Larsen, R; Lazarus, D M; Ozben, C; Semertzidis, Y K; Tsang, Thomas; Srinivasan-Rao, T

    2001-01-01

    We have made an observation of 45 MeV electron beam bunches using the nondestructive electro-optical (EO) technique. The amplitude of the EO modulation was found to increase linearly with electron beam charge and decrease inversely with the optical beam path distance from the electron beam. The risetime of the signal was bandwidth limited by our detection system to \\~70ps. An EO signal due to ionization caused by the electrons traversing the EO crystal was also observed. The EO technique may be ideal for the measurement of bunch structure with femtosecond resolution of relativistic charged particle beam bunches.

  5. 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.

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

    Science.gov (United States)

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

    2016-03-01

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

  7. Bunch Length Monitoring at the A0 Photoinjector Using a Quasi-Optical Schottky Detector

    Energy Technology Data Exchange (ETDEWEB)

    Kazakevich, G.; Davidsaver, M.; Edwards, H.; Fliller, R.; Koeth, T.; Lumpkin, A.; Nagaitsev, S.; Ruan, J.; Thurman-Keup, R.; /Fermilab; Jeong, Y.U.; /KAERI, Taejon; Kubarev, V.; /Novosibirsk, IYF

    2009-05-01

    Noninvasive bunch duration monitoring has a crucial importance for modern accelerators intended for short wavelength FEL's, colliders and in some beam dynamics experiments. Monitoring of the bunch compression in the Emittance Exchange Experiment at the A0 Photoinjector was done using a parametric presentation of the bunch duration via Coherent Synchrotron Radiation (CSR) emitted in a dipole magnet and measured with a wideband quasi-optical Schottky Barrier Detector (SBD). The monitoring resulted in a mapping of the quadrupole parameters allowing a determination of the region of highest compression of the bunch in the sub-picosecond range. The obtained data were compared with those measured using the streak camera. A description of the technique and the results of simulations and measurements are presented and discussed in this report.

  8. 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.

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

    CERN Document Server

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

    2016-01-01

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

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

    CERN Document Server

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

    2009-01-01

    We describe a novel technique to characterize ultrashort electron bunches in X-ray 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.

  11. 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.

  12. A Single Shot, Sub-picosecond Beam Bunch Characterization with Electro-optic Techniques

    CERN Document Server

    Semertzidis, Y K; Castillo, V; Larsen, R; Lazarus, D M; Nikas, D; Ozben, C; Srinivasan-Rao, T; Stillman, A; Tsang, Thomas; Kowalski, L A

    2001-01-01

    In the past decade, the bunch lengths of electrons in accelerators have decreased dramatically to the range of a few picoseconds \\cite{Uesaka94,Trotz97}. Measurement of the length as well as the longitudinal profile of these short bunches have been a topic of research in a number of institutions \\cite{Uesaka97,Liu97,Hutchins00}. One of the techniques uses the electric field induced by the passage of electrons in the vicinity of a birefringent crystal to change its optical characteristics. Well-established electro-optic techniques can then be used to measure the temporal characteristics of the electron bunch. In this paper we present a novel, non-invasive, single-shot approach to improve the resolution to tens of femtoseconds so that sub-millimeter bunch length can be measured.

  13. LHC MD 1087: Controlled Longitudinal Emittance Blow-up with Short Bunches

    CERN Document Server

    Timko, Helga; Esteban Muller, Juan; Jaussi, Michael; Lasheen, Alexandre; Shaposhnikova, Elena; CERN. Geneva. ATS Department

    2017-01-01

    The aim of the MD was to study the controlled longitudinal emittance blow-up applied during the ramp with bunches that are slightly shorter than operational. Earlier MDs in 2015 have shown that with a short target bunch length, the blow-up is less controlled and a bifurcation of bunch lengths occurs. The presented measurements show that the bifurcation is independent of the presence of the bunch length feedback, pointing towards an intensity-dependent phenomenon, originating from a synchrotron frequency shift with intensity. Accurate measurements of synchrotron frequency shift with intensity are presented as well. The measurements took place between 22nd August 2016, 19:00 and 23rd August 2016, 04:00.

  14. 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.

  15. 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.

  16. 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.

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

    CERN Document Server

    Bassi, G

    2005-01-01

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

  18. 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.

  19. 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.)

  20. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-07-01

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

  2. Spherical nanocrystalline cellulose (NCC) from oil palm empty fruit bunch pulp via ultrasound assisted hydrolysis.

    Science.gov (United States)

    Zianor Azrina, Z A; Beg, M Dalour H; Rosli, M Y; Ramli, Ridzuan; Junadi, Norhafzan; Alam, A K M Moshiul

    2017-04-15

    Nanocrystalline cellulose (NCC) was isolated from oil palm empty fruit bunch pulp (EFBP) using ultrasound assisted acid hydrolysis. The obtained NCC was analysed using FESEM, XRD, FTIR, and TGA, and compared with raw empty fruit bunch fibre (REFB), empty fruit bunch pulp (EFBP), and treated empty fruit bunch pulp (TEFBP). Based on FESEM analysis, it was found that NCC has a spherical shaped after acid hydrolysis with the assistance of ultrasound. This situation was different compared to previous studies that obtained rod-like shaped of NCC. Furthermore, the crystallinity of NCC is higher compared to REFB and EFBP. According to thermal stability, the NCC obtained shows remarkable sign of high thermal stability compared to REFB and EFBP.

  3. Electron Bunch Length Measurements in the E-167 Plasma Wakefield Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Blumenfeld, I.; Auerbach, D.; Berry, M.; Clayton, C.E.; Decker, F.J.; Hogan, M.J.; Huang, Cheng-Kun; Ischebeck, R.; Iverson, R.; Johnson, D.; Joshi, C.; Katsouleas, T.; Kirby, N.; Lu, Wei; Marsh, K.A.; Mori, W.B.; Muggli, P.; Oz, E.; Siemann, R.H.; Walz, D.; Zacherl, W.; /SLAC /UCLA /Southern California U.

    2007-03-27

    Bunch length is of prime importance to beam driven plasma wakefield acceleration experiments due to its inverse relationship to the amplitude of the accelerating wake. We present here a summary of work done by the E167 collaboration measuring the SLAC ultra-short bunches via autocorrelation of coherent transition radiation. We have studied material transmission properties and improved our autocorrelation traces using materials with better spectral characteristics.

  4. Bunch length measurement at Tsinghua Thomson scattering X-ray source

    Institute of Scientific and Technical Information of China (English)

    DU Ying-Chao; HUA Jian-Fei; YAN Li-Xin; DU Qiang; HUANG Wen-Hui; TANG Chuan-Xiang

    2011-01-01

    The length of electron beam from a photocathode RF gun is determined by a spectrometer, according to the relative energy spread induced by the bunch length during the acceleration in a linac. For a photocathode RF gun, different laser injected phase and beam charge are studied. The compression is changed for the different laser phases, as from 10° to 30°, and the bunch length is lengthened due to the strong longitudinal space charge force, caused by the increased charge.

  5. 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.

  6. 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.

  7. Electric and Magnetic Fields Generated by a Charged Bunch between Parallel Conducting Plates

    Directory of Open Access Journals (Sweden)

    B. Levchenko

    2010-01-01

    Full Text Available Image fields generated by a bunch of charged particles between two parallel perfectly conducting plates are studied in detail. We derive exact analytical expressions for external fields of a charged relativistic bunch with a circular cross-section. Summation of image fields by the direct method invented by Laslett allows the infinite series to be represented in terms of elementary trigonometric functions.

  8. 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.

  9. Seeding of self-modulation instability of a long electron bunch in a plasma.

    Science.gov (United States)

    Fang, Y; Yakimenko, V E; Babzien, M; Fedurin, M; Kusche, K P; Malone, R; Vieira, J; Mori, W B; Muggli, P

    2014-01-31

    We demonstrate experimentally that a relativistic electron bunch shaped with a sharp rising edge drives plasma wakefields with one to seven periods along the bunch as the plasma density is increased. The plasma density is varied in the 10(15)-10(17)  cm(-3) range. The wakefields generation is observed after the plasma as a periodic modulation of the correlated energy spectrum of the incoming bunch. We choose a low bunch charge of 50 pC for optimum visibility of the modulation at all plasma densities. The longitudinal wakefields creating the modulation are in the MV/m range and are indirect evidence of the generation of transverse wakefields that can seed the self-modulation instability, although the instability does not grow significantly over the short plasma length (2 cm). We show that the seeding provides a phase reference for the wakefields, a necessary condition for the deterministic external injection of a witness bunch in an accelerator. This electron work supports the concept of similar experiments in the future, e.g., SMI experiments using long bunches of relativistic protons.

  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. 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.

  12. Generation of attosecond electron bunches in a laser-plasma accelerator using a plasma density upramp

    Energy Technology Data Exchange (ETDEWEB)

    Weikum, M.K., E-mail: maria.weikum@desy.de [Deutsches Elektronensynchrotron (DESY), Bdg. 30b, Notkestr. 85, 22607 Hamburg (Germany); Department of Physics, University of Strathclyde, G4 0NG Glasgow (United Kingdom); Li, F.Y. [Department of Physics, University of Strathclyde, G4 0NG Glasgow (United Kingdom); Assmann, R.W. [Deutsches Elektronensynchrotron (DESY), Bdg. 30b, Notkestr. 85, 22607 Hamburg (Germany); Sheng, Z.M. [Department of Physics, University of Strathclyde, G4 0NG Glasgow (United Kingdom); Laboratory for Laser Plasmas and Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Jaroszynski, D. [Department of Physics, University of Strathclyde, G4 0NG Glasgow (United Kingdom)

    2016-09-01

    Attosecond electron bunches and attosecond radiation pulses enable the study of ultrafast dynamics of matter in an unprecedented regime. In this paper, the suitability for the experimental realization of a novel scheme producing sub-femtosecond duration electron bunches from laser-wakefield acceleration in plasma with self-injection in a plasma upramp profile has been investigated. While it has previously been predicted that this requires laser power above a few hundred terawatts typically, here we show that the scheme can be extended with reduced driving laser powers down to tens of terawatts, generating accelerated electron pulses with minimum length of around 166 attoseconds and picocoulombs charge. Using particle-in-cell simulations and theoretical models, the evolution of the accelerated electron bunch within the plasma as well as simple scalings of the bunch properties with initial laser and plasma parameters are presented. - Highlights: • LWFA with an upramp density profile can trap and accelerate sub-fs electron beams. • A reduction of the necessary threshold laser intensity by a factor 4 is presented. • Electron properties are tuned by varying initial laser and plasma parameters. • Simulations predict electron bunch lengths below 200 attoseconds with pC charge. • Strong bunch evolution effects and a large energy spread still need to be improved.

  13. Stably propagating trains of attosecond electron bunches generated along the target back

    Science.gov (United States)

    Pan, K. Q.; Zheng, C. Y.; Cao, L. H.; Liu, Z. J.; He, X. T.

    2016-09-01

    With the help of particle-in-cell simulations, we show a stably propagating train of attosecond ( 10 - 18 s) electron bunches which are generated along the target back surface via laser-solid interactions. The electron bunches are generated by the oscillating electric fields of the surface plasma wave. Because of the combinational effects of the electrostatic field and the static magnetic field on the target back surface, the electron bunches are stably propagating along the target back surface, which means they are totally separated from the laser pulse. The averaged energy of these electron bunches is over 20 MeV , the maximum averaged density is about 6 n c (where n c ≈ 1.1 × 10 21 cm - 3 is the critical density of the incident laser), and the averaged duration is less than 200 as. Such electron bunches are easily applied to the generation of attosecond x-rays via Compton backscattering. The energy conversion efficiency from the laser to the attosecond electron bunches is about 1.5%.

  14. A multi-length bunch design for electron storage rings with odd buckets

    Institute of Scientific and Technical Information of China (English)

    ZHU Liang-Jing; LI Wei-Min; WANG Lin; XIANG Dao; HUANG Xiao-Biao

    2015-01-01

    A scheme with two superconducting RF cavities is designed to upgrade electron storage rings with odd buckets to multi-length bunches.In this paper,the Hefei Light Source Ⅱ (HLS Ⅱ) is given as an example for odd buckets.As it is designed for 45 buckets,which is a multiple of 3,simultaneous generation of three different lengths of bunches is proposed with the presently applied user optics.The final result,without low-α optics,is to fill HLS Ⅱ with long bunches of length 50 ps,medium bunches of 23 ps and short bunches of 6 ps.Every third bucket can be filled with short bunches,of which the current limit is up to 6.6 mA,more than 60 times the limit for low-α mode.Moreover,particle tracking simulations to examine the beam dynamics,performed by ELEGANT,and calculations of the beam instabilities are presented in this paper.

  15. 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.)

  16. Calculation of coupled bunch effects in the synchrotron light source BESSY VSR

    Energy Technology Data Exchange (ETDEWEB)

    Ruprecht, Martin

    2016-02-22

    In the scope of this thesis, the strength of coupled bunch instabilities (CBIs) driven by longitudinal monopole higher order modes (HOMs) and transverse dipole and quadrupole HOMs is evaluated for the upgrade project BESSY Variable Pulse Length Storage Ring (BESSY VSR) at Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH (HZB), based on analytic calculations and tracking simulations, and compared to the performance of an active bunch-by-bunch feedback (BBFB). Algorithms for tracking codes are derived, and a semi-empirical formula for the estimation of transverse quadrupole CBIs is presented. CBI studies are an integral part of the benchmarking of the cavity models for BESSY VSR and have been accompanying and influencing their entire design process. Based on the BESSY VSR cavity model with highly advanced HOM damping, beam stability is likely to be reached with a BBFB system, independent of the bunch fill pattern. Additionally, measurements of CBIs have been performed at BESSY II and the Metrology Light Source of the Physikalisch-Technische Bundesanstalt (MLS), where the longitudinal long range impedance was characterized. Transient beam loading is evaluated by means of analytic formulas and new experimentally verified tracking codes. For the baseline bunch fill pattern of BESSY VSR, it is shown that the particular setup of cavity frequencies amplifies the transient effect on the long bunch, limiting its elongation and potentially resulting in increased Touschek losses.

  17. Studies of a Proton Bunch Phase Monitor for Range Verification in Proton Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Werner, T.; Golnik, C.; Enghardt, W.; Petzoldt, J.; Kormoll, T.; Pausch, G. [Technische Universitaet Dresden, OncoRay, PF 41, 01307 Dresden (Germany); Straessner, A. [Technische Universitaet Dresden, Institute for Nuclear and Particle Physics, Zellescher Weg 19, 01069 Dresden (Germany); Roemer, K.; Dreyer, A.; Hueso-Gonzalez, F.; Enghardt, W. [Helmholtz-Zentrum Dresden-Rossendorf, PF 510 119, 01314 Dresden (Germany)

    2015-07-01

    A primary subject of the present research in particle therapy is to ensure the precise irradiation of the target volume. The prompt gamma timing (PGT) method provides one possibility for in vivo range verification during the irradiation of patients. Prompt gamma rays with high energies are emitted promptly due to nuclear reactions of protons with tissue. The arrival time of these gammas to the detector reflects the stopping process of the primary protons in tissue and is directly correlated to the range. Due to the time resolution of the detector and the proton bunch time spread, as well as drifts of the bunch phase with respect to the accelerator frequency, timing spectra are smeared out and compromise the accuracy of range information intended for future clinical applications. Nevertheless, counteracting this limitation and recovering range information from the PGT measured spectra, corrections using a bunch phase monitor can be performed. A first prototype of bunch phase monitor was tested at GSI Darmstadt, where measurements of the energy correlation profile of the ion bunches were performed. At the ELBE accelerator at Helmholtz-Zentrum Dresden-Rossendorf (HZDR), set up to provide bremsstrahlung photons in very short pulses, a constant fraction algorithm for the incoming digital signals was evaluated, which is used for optimizing the time resolution. Studies of scattering experiments with different thin targets and detector positions are accomplished at Onco Ray Dresden, where a clinical proton beam is available. These experiments allow a basic characterization of the proton bunch structure and the detection yield. (authors)

  18. Modulated Electron Bunch with Amplitude Front Tilt in an Undulator

    CERN Document Server

    Geloni, Gianluca; Saldin, Evgeni

    2015-01-01

    In a previous paper we discussed the physics of a microbunched electron beam kicked by the dipole field of a corrector magnet by describing the kinematics of coherent undulator radiation after the kick. We demonstrated that the effect of aberration of light supplies the basis for understanding phenomena like the deflection of coherent undulator radiation by a dipole magnet. We illustrated this fact by examining the operation of an XFEL under the steady state assumption, that is a harmonic time dependence. We argued that in this particular case the microbunch front tilt has no objective meaning; in other words, there is no experiment that can discriminate whether an electron beam is endowed with a microbunch front tilt of not. In this paper we extend our considerations to time-dependent phenomena related with a finite electron bunch duration, or SASE mode of operation. We focus our attention on the spatiotemporal distortions of an X-ray pulse. Spatiotemporal coupling arises naturally in coherent undulator radi...

  19. 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.

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

    Science.gov (United States)

    Ratnasingam, Jegatheswaran; Chew Tek, Tee; Farrokhpayam, Saied Reza

    A series of machining experiments on the Oil-Palm Empty Fruit Bunch (OPEFB) particleboard were carried out using a CNC router, to evaluate the tool wearing properties of the composite in comparison to the conventional wood-material particleboard. A single-fluted tungsten-carbide router bit (12 mm φ, 18 000 rpm), with a rake angle of 15° was used in this experiment, in which the depth of cut was 1.5 mm and feed speed was 4.5 m min-1. The router bit machined the edge of the board, moving along the full length before returning to repeat the cycle. The tool was examined for the extent of wear after complete failure had occurred. The result found that the wear pattern was similar in the oil-palm based particleboard and the wood-based particleboard, but the former was twice more abrasive compared to the latter. Microscopic examination of the cutter edge revealed greater incidence of micro-fracture when cutting the oil-palm based particleboard, indicating the presence of hard impurities in the composite. From an economic perspective, the tooling cost for machining oil-palm based particleboard is estimated to be twice of the cost for machining wood-based particleboard. This study shows that the machining properties of oil-palm based particleboard will be a primary concern, if the board is to find widespread application as a potential substitute for wood-based particleboard.

  1. 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.

  2. 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.

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

    Science.gov (United States)

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

    2015-04-01

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

  4. 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.

  5. 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.)

  6. A self-focusing, high transformer ratio, collinear plasma dielectric wakefield accelerator driven by a ramped bunch train

    Science.gov (United States)

    Sotnikov, Gennadij V.; Marshall, Thomas C.; Shchelkunov, Sergey V.; Hirshfield, Jay L.

    2017-03-01

    New results of studies of wakefield excitation by a ramped bunch train in a collinear, single-channel dielectriclined THz-wakefield accelerator structure that is filled with a low-temperature plasma are presented. A novel ramped train of drive bunches, together with plasma filling part of the transport channel, makes possible substantial improvement of the transformer ratio of the multimode collinear device to 6:1 while the plasma could stabilize the transverse motion of the drive and witness bunches.

  7. Perturbation-minimized triangular bunch for high-transformer ratio using a double dogleg emittance exchange beam line

    Science.gov (United States)

    Ha, G.; Cho, M. H.; Gai, W.; Kim, K.-J.; Namkung, W.; Power, J. G.

    2016-12-01

    The longitudinal shape, i.e., the current profile, of an electron bunch determines the transformer ratio in a collinear wakefield accelerator and thus methods are sought to control the longitudinal bunch shape. The emittance exchange (EEX) appears to be promising for creating a precisely controlled longitudinal bunch shapes. The longitudinal shape is perturbed by two sources: higher-order terms in the beam line optics and collective effects and these perturbations can lead to a significant drop of the transformer ratio. In this paper, we analytically and numerically investigate the perturbation to an ideal triangular longitudinal bunch shape and propose methods to minimize it.

  8. 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

  9. Nonlinear wake amplification by an active medium in a cylindrical waveguide using a modulated trigger bunch

    Institute of Scientific and Technical Information of China (English)

    Zeev; Toroker; Miron; Voin; Levi; Schchter

    2014-01-01

    Cerenkov wake amplification can be used as an accelerating scheme,in which a trigger bunch of electrons propagating inside a cylindrical waveguide filled with an active medium generates an initial wake field.Due to the multiple reflections inside the waveguide,the wake may be amplified significantly more strongly than when propagating in a boundless medium.Sufficiently far away from the trigger bunch the wake,which travels with the same phase velocity as the bunch,reaches saturation and it can accelerate a second bunch of electrons trailing behind.For a CO2 gas mixture our numerical and analytical calculations indicate that a short saturation length and a high gradient can be achieved with a large waveguide radius filled with a high density of excited atoms and a trigger bunch that travels at a velocity slightly above the Cerenkov velocity.To obtain a stable level of saturated wake that will be suitable for particle acceleration,it is crucial to satisfy the single-mode resonance condition,which requires high accuracy in the waveguide radius and the ratio between the electron phase velocity and the Cerenkov velocity.For single-mode propagation our model indicates that it is feasible to obtain gradients as high as GV m-1 in a waveguide length of cm.

  10. Two-photon super bunching of thermal light via multiple two-photon-path interference

    CERN Document Server

    Hong, Peilong; Zhang, Guoquan

    2012-01-01

    We propose a novel scheme to achieve two-photon super bunching of thermal light through multiple two-photon-path interference, in which two mutually first-order incoherent optical channels are introduced by inserting a modified Michelson interferometer into a traditional two-photon HBT interferometer, and the bunching peak-to-background ratio can reach 3 theoretically. Experimentally, the super bunching peak-to-background ratio was measured to be 2.4, much larger than the ratio 1.7 measured with the same thermal source in a traditional HBT interferometer. The peak-to-background ratio of two-photon super bunching of thermal light can be increased up to $2\\times1.5^n$ by inserting cascadingly $n$ pairs of mutually first-order incoherent optical channels into the traditional two-photon HBT interferometer. The two-photon super bunching of thermal light should be of great significance in improving the visibility of classical ghost imaging.

  11. Fiber laser pumped high power mid-infrared laser with picosecond pulse bunch output.

    Science.gov (United States)

    Wei, Kaihua; Chen, Tao; Jiang, Peipei; Yang, Dingzhong; Wu, Bo; Shen, Yonghang

    2013-10-21

    We report a novel quasi-synchronously pumped PPMgLN-based high power mid-infrared (MIR) laser with picosecond pulse bunch output. The pump laser is a linearly polarized MOPA structured all fiberized Yb fiber laser with picosecond pulse bunch output. The output from a mode-locked seed fiber laser was directed to pass through a FBG reflector via a circulator to narrow the pulse duration from 800 ps to less than 50 ps and the spectral FWHM from 9 nm to 0.15 nm. The narrowed pulses were further directed to pass through a novel pulse multiplier through which each pulse was made to become a pulse bunch composing of 13 sub-pulses with pulse to pulse time interval of 1.26 ns. The pulses were then amplified via two stage Yb fiber amplifiers to obtain a linearly polarized high average power output up to 85 W, which were then directed to pass through an isolator and to pump a PPMgLN-based optical parametric oscillator via quasi-synchronization pump scheme for ps pulse bunch MIR output. High MIR output with average power up to 4 W was obtained at 3.45 micron showing the feasibility of such pump scheme for ps pulse bunch MIR output.

  12. 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.

  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. 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...

  15. 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.

  16. 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)

  17. Probing intensity limits of LHC-Type bunches in CERN SPS with nominal optics

    CERN Document Server

    Adrian, G; Andujar, O; Argyropoulos, T; Axensalva, J; Baldy, J; Bartosik, H; Cettour Cave, S; Chapuis, F; Comblin, JF; Cornelis, K; Cotte, D; Cunnington, K; Damerau, H; Delrieux, M; Duran-Lopez, JL; Esteban Mueller, J; Findlay, A; Fleuret, J; Follin, F; Freyermuth, P; Genoud, H; Gilardoni, S; Guerrero, A; Hancock, S; Hanke, K; Hans, O; Hazelaar, R; Höfle, W; Jensen, L; Kuczerowski, J; Le Borgne, Y; Maillet, R; Manglunki, D; Massot, S; Matli, E; Métral, G; Métral, E; Mikulec, B; Nonglaton, JM; Ovalle, E; Papaphilippou, Y; Pereira, L; Peters, F; Rey, A; Ridewood, J; Rumolo, G; Salvant, B; Sanchez Alvarez, JL; Shaposhnikova, E; Steerenberg, R; Steinhagen, R; Tan, J; Vandorpe, B; Veyrunes, E

    2011-01-01

    Some of the upgrade scenarios of the high-luminosity LHC require large intensity per bunch from the injector chain. Single bunch beams with intensities of up to 3.5 to 4e11 p/b and nominal emittances were successfully produced in the PS Complex and delivered to the SPS in 2010. This contribution presents results of studies with this new intense beam in the SPS to probe single bunch intensity limitations with nominal gamma transition. In particular, the vertical Transverse Mode Coupling Instability (TMCI) threshold with low chromaticity was observed at 1.6e11 p/b for single nominal LHC bunches in the SPS. With increased vertical chromaticity, larger intensities could be injected, stored along the flat bottom and accelerated up to 450 GeV/c. However, significant losses and/or transverse emittance blow up were then observed. Longitudinal and transverse optimization efforts in the PSB, PS and SPS were put in place to minimize this beam degradation and succeeded to obtain single 2.5e11 p/b LHC type bunches with sa...

  18. Ion Emittance Growth Due to Focusing Modulation from Slipping Electron Bunch

    Energy Technology Data Exchange (ETDEWEB)

    Wang, G. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2015-02-17

    Low energy RHIC operation has to be operated at an energy ranging from γ = 4.1 to γ = 10. The energy variation causes the change of revolution frequency. While the rf system for the circulating ion will operate at an exact harmonic of the revolution frequency (h=60 for 4.5 MHz rf and h=360 for 28 MHz rf.), the superconducting rf system for the cooling electron beam does not have a frequency tuning range that is wide enough to cover the required changes of revolution frequency. As a result, electron bunches will sit at different locations along the ion bunch from turn to turn, i.e. the slipping of the electron bunch with respect to the circulating ion bunch. At cooling section, ions see a coherent focusing force due to the electrons’ space charge, which differs from turn to turn due to the slipping. We will try to estimate how this irregular focusing affects the transverse emittance of the ion bunch.

  19. High quality electron bunch generation with CO2-laser-plasma interaction

    Science.gov (United States)

    Zhang, Lingang; Shen, Baifei; Xu, Jiancai; Ji, Liangliang; Zhang, Xiaomei; Wang, Wenpeng; Zhao, Xueyan; Yi, Longqing; Yu, Yahong; Shi, Yin; Xu, Tongjun; Xu, Zhizhan

    2015-02-01

    CO2 laser-driven electron acceleration in low-density plasma is demonstrated using particle-in-cell simulation. An intense CO2 laser pulse of long wavelength excites a wake bubble that has a large elongated volume for accelerating a large number of electrons before reaching the charge saturation limit. A transversely injected laser pulse is used to induce and control the electron injection. It is found that an electron bunch with total charge up to 10 nC and absolute energy spread less than 16 MeV can be obtained. As a result, the charge per energy interval of the bunch reaches up to 0.6 nC/MeV. Intense CO2-laser based electron acceleration can provide a new direction for generating highly charged electron bunches with low energy spread, which is of much current interest, especially for table-top X-ray generation.

  20. 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.

  1. On Compensating Tune Spread Induced by Space Charge in Bunched Beams

    CERN Document Server

    Litvinenko, Vladimir N

    2014-01-01

    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. 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. 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.

  2. Adjustment of a double drift harmonic buncher and bunch shape measurements

    CERN Document Server

    Knott, J; Weiss, M

    1976-01-01

    The longitudinal beam matching of the new 50 MeV linac is achieved with a double drift harmonic buncher. For optimum bunching efficiency the RF phase difference between the two cavities should be known and controlled to about 1 degrees (at 202.56 MHz). The adjustment of the RF levels and phases is based on observations of the bunch form via a broad-band probe connected to a travelling wave oscilloscope. The time base is tightly locked to the RF by a specially developed circuit allowing a systematic study of different bunching conditions. A comparison is made between some preliminary measurements and the waveforms predicted by a simplified theory. (3 refs).

  3. Unveiling the internal microstructures of relativistic electron bunches using a "time-stretch" strategy

    CERN Document Server

    Roussel, E; Szwaj, M Le Parquier C; Manceron, L; Brubach, J -B; Tordeux, M -A; Ricaud, J -P; Cassinari, L; Labat, M; Couprie, M -E; Roy, P; Bielawski, S

    2014-01-01

    Relativistic electron bunches are powerful light sources, which are largely exploited in synchrotron radiation facilities, and are crucial for most sciences. However, electrons bunches suffer from instabilities, leading to spontaneous spatial structure formation. This effect --recalling fluid turbulence issues-- represents a fundamental limitation for light sources, and simultaneously an opportunity because the structures emit high powers of terahertz radiation ($>$10000 times normal synchrotron radiation). Up to now, though crucial for understanding and mastering synchrotron sources, observations of the structures remained a largely open problem, because of their extreme evolution speed. Here we demonstrate the possibility of direct observation by adapting a technique from photonics, {\\it time-strech}, consisting in "slowing-down" the phenomena prior to recording. As a main result, we present the first recording of electron bunch microstructures versus time, with submillimeter resolution, in a storage ring. ...

  4. Coherent transition radiation diagnostic for electron bunch shape measurement at FELIX

    Science.gov (United States)

    Ding, Meisong; Weits, H. H.; Oepts, D.

    1997-02-01

    An optical autocorrelation system using coherent transition radiation has been set up to determine the electron bunch shape at FELIX. A polarisation interferometer and a 10 × 10 mm 2 pyroelectric detector are used to allow operation over a wide range of wavelength (from 30 μm to 10 mm) without strong variation in efficiency. An evacuated 15 m long overmoded waveguide is used to transport the transition radiation to the experimental area. The intensity of the transition radiation was measured and compared with our calculation. The phase-retrieval technique applied to the measured spectrum provides details of the electron bunch. The bunch shapes have been studied at different buncher phase settings. Measurements of coherent transition radiation and coherent undulator radiation are compared.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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].

  14. 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.

  15. 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.

  16. 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 (~20 pC), 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.

  17. 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.

  18. 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.

  19. Multiple-bunch-length operating mode design for a storage ring using hybrid low alpha and harmonic cavity method

    Science.gov (United States)

    Gao, Weiwei; Wang, Lin; Li, Heting

    2017-03-01

    In this paper we design a simultaneous three bunch length operating mode at the HLS-II (Hefei Light Source II) storage ring by installing two harmonic cavities and minimizing the momentum compaction factor. The short bunches (2.6 mm) presented in this work will meet the requirement of coherent millimeter-wave and sub-THz radiation experiments, while the long bunches (20 mm) will efficiently increase the total beam current. Therefore, this multiple-bunch-length operating mode allows present synchrotron users and coherent millimeter-wave users (or sub THz users) to carry out their experiments simultaneously. Since the relatively low energy characteristic of HLS-II we achieve the multiple-bunch-length operating mode without multicell superconducting RF cavities, which is technically feasible.

  20. 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

  1. Modification of the LEP electrostatic separator systems for operation with bunch trains

    CERN Document Server

    Balhan, B; Carlier, E; Deluen, J P; Dieperink, J H; Garrel, N; Goddard, B; Guinand, R; Kalbreier, Willi; Laffin, M; Lamont, M; Mertens, V; Poole, John; Verhagen, H

    1996-01-01

    To meet the LEP2 luminosity requirements for W-pair production, it is planned to operate LEP with Bunch Trains from 1995 onwards. This new mode of operation entails significant modification both to the existing separator hardware and its control system. The changes have been implemented so as to provide maximum flexibility for the realisation of the Bunch Train scheme, and also make a return to operation with Pretzel separation possible during 1995. Two LEP Interaction Points (IP) were equipped with new separators in late 1994, enabling first tests with the collision of one train of four e+ bunches with one train of e- bunches. During the 1994/95 shutdown, four separators have been installed in the two remaining experimental IPs, and eight separators in the non-experimental IP have been displaced to new positions. Details are given of optics requirements for the separator installations, the polarity of the closed orbit separator bumps, system modifications, and performance considerations. Results are presente...

  2. 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...

  3. 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.

  4. Bunch length measurement at Tsinghua Thomson scattering X-ray source

    Institute of Scientific and Technical Information of China (English)

    DU Ying-Chao; HUA Jian-Fei; YAN Li-Xin; DU Qiang; HUANG Wcn-Hui; TANG Chuan-Xiang

    2011-01-01

    The length of electron beam from a photocathode RF gun is determined by a spectrometer, according to the relative energy spread induced by the bunch length during the acceleration in a linac. For a photocathode RF gun, different laser injected phase and b

  5. Bunching of an Intense Electron-Beam Extracted from a Triode Gun Modulated at 1 Ghz

    NARCIS (Netherlands)

    van der Geer, C. A. J.; Bakker, R. J.; van der Meer, A. F. G.; van Amersfoort, P. W.; Gillespie, W. A.; Saxon, G.

    1991-01-01

    We present measurements of the bunch length and emittance of a high-current electron beam, which is extracted from a triode modulated at 1 GHz and subsequently compressed by means of velocity modulation in a prebuncher cavity. The prebuncher is detuned by about 1 MHz in order to ensure that the tota

  6. Coherent transition radiation diagnostic for electron bunch shape measurement at FELIX

    NARCIS (Netherlands)

    Ding, M. S.; Weits, H. H.; Oepts, D.

    1997-01-01

    An optical autocorrelation system using coherent transition radiation has been set up to determine the electron bunch shape at FELIX. A polarisation interferometer and a 10 x 10 mm(2) pyroelectric detector are used to allow operation over a wide range of wavelength (from 30 mu m to 10 mm) without st

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

    Science.gov (United States)

    Sütterlin, Daniel; Erni, Daniel; Schlott, Volker; Sigg, Hans; Jäckel, Heinz; Murk, Axel

    2010-10-01

    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.

  8. 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

  9. 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.

  10. A new type of bunch compressor and seeding of a short-wavelength coherent radiation.

    Energy Technology Data Exchange (ETDEWEB)

    Zholents, A. A.; Zolotorev, M. S. (Accelerator Systems Division (APS)); (LBNL)

    2011-05-30

    Transverse-to-longitudinal emittance exchange was proposed in [1] as a tool for an effective matching of the electron beam phase space to requirements of a possible application. Here we propose a new purpose, namely, use of two consecutive emittance exchanges equipped with the telescope between them for a bunch compression that can be done without the energy chirp in the electron bunch. In principle it allows to reduce the electron peak current in the linac by moving the bunch compressor to the end of the linac and, thus, to relax collective effects associated with high peak currents. It is also possible to have a split-action compression when the first part is done inside the low-energy part of the linac and the second and final part is done after the linac. We also demonstrate how proposed bunch compressor can be used for frequency up-conversion of the energy modulation provided by the laser interacting with the electron beam and thus can prepare a significantly higher frequency seed for seeded free-electron lasers. The same approach can be used for a frequency down-conversion that can be useful for generation of THz radiation.

  11. Studies of Longitudinal Coupled-Bunch Instabilities in the LHC Injectors Chain

    CERN Document Server

    AUTHOR|(CDS)2087149; Migliorati, M

    Among several challenging objectives of the LHC Injectors Upgrade project, one aim is to double the beam intensity of the CERN Proton Synchrotron (PS) in order to achieve the integrated luminosity target of the High-Luminosity LHC project. A known limitation to reach the required high intensity is caused by the longitudinal coupled-bunch (CB) oscillations developing above the PS transition energy. The unwanted oscillations induce large bunch-to-bunch intensity variations not compatible with the specifications of the future LHC-type beams. In 2014 a new longitudinal kicker cavity has been installed, the Finemet cavity, as a part of the new digital coupled-bunch feedback (FB) system. The Finemet cavity allows with its large frequency bandwidth, to damp all the expected oscillation modes simultaneously. In the framework of this PhD study the impedance contribution of this equipment has been analyzed starting from the present knowledge of the machine impedance. A model of both the 10 MHz and the Finemet has been ...

  12. 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.

  13. 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.

  14. Development and commissioning of a double-prism spectrometer for the diagnosis of femtosecond electron bunches

    Energy Technology Data Exchange (ETDEWEB)

    Wunderlich, Steffen

    2016-12-15

    Free-electron lasers as accelerator-driven light sources and wakefield-based acceleration in plasmas require the knowledge of the longitudinal extension and the longitudinal current profile of the involved electron bunches. These bunches can yield lengths below 10 μm, or durations shorter than approx. 33 fs, as well as charges less than 30 pC. During this work, transition radiation from relativistic electron bunches was investigated in the mid-infrared wavelength regime. A spectrometer using an arrangement of two consecutive zinc selenide prisms was developed, built and commissioned. The instrument covers the spectral range from 2 μm to 18 μm in a single shot. Measurements with the double-prism spectrometer were conducted at the FEL facilities FLASH at DESY in Hamburg, Germany and FELIX at the Radboud Universiteit in Nijmegen, The Netherlands. The assessment of the spectrometer and comparative studies with established diagnostic devices at FLASH show high signal-to-noise ratios at bunch charges below 10 pC and confirm the obtained results.

  15. Single-bunch emittance dilution in the perfect ILC main linac

    Institute of Scientific and Technical Information of China (English)

    WANG Dou; GAO Jie

    2011-01-01

    In the ILC(International Linear Collider)main linac, low emittance preservation is the most important issue for beam dynamics study. As the main sources of emittance dilution, the dispersive and wakefield effects were studied in this paper. The theoretical calculations and numerical simulations of these two effects on single-bunch emittance dilution, without any misalignment errors, are presented in detail.

  16. 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.

  17. Geometric analysis of phase bunching in the central region of cyclotron

    Energy Technology Data Exchange (ETDEWEB)

    Miyawaki, Nobumasa, E-mail: miyawaki.nobumasa@jaea.go.jp [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Fukuda, Mitsuhiro [Research Center for Nuclear Physics, Osaka University, 10-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Kurashima, Satoshi; Kashiwagi, Hirotsugu; Okumura, Susumu [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Arakawa, Kazuo [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Gunma University Heavy Ion Medical Center, Gunma University, 3-39-22 Showa-Machi, Maebashi, Gunma 371-8511 (Japan); Kamiya, Tomihiro [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan)

    2013-07-01

    An optimum condition for realizing phase bunching in the central region of a cyclotron was quantitatively clarified by a simplified geometric trajectory analysis of charged particles from the first to the second acceleration gap. The phase bunching performance was evaluated for a general case of a cyclotron. The phase difference of incident particles at the second acceleration gap depends on the combination of four parameters: the acceleration harmonic number h, the span angle θ{sub D} of the dee electrode, the span angle θ{sub F} from the first to the second acceleration gap, the ratio R{sub V} of the peak acceleration voltage between the cyclotron and ion source. Optimum values of θ{sub F} for phase bunching were limited by the relationship between h and θ{sub D}, which is 90°/h+θ{sub D}/2≤θ{sub F}≤180°/h+θ{sub D}/2, and sin θ{sub F}>0. The phase difference with respect to the reference particle at the second acceleration gap is minimized for voltage-ratios between two and four for an initial phase difference within 40 RF degrees. Although the slope of the first acceleration gap contributes to the RF phase at which the particles reach the second acceleration gap, phase bunching was not affected. An orbit simulation of the AVF cyclotron at the Japan Atomic Energy Agency verifies the evaluation based on geometric analysis.

  18. 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

  19. Violation of the transit-time limit toward generation of ultrashort electron bunches with controlled velocity chirp

    Science.gov (United States)

    Jeon, Seok-Gy; Shin, Dongwon; Hur, Min Sup

    2016-09-01

    Various methods to generate ultrashort electron bunches for the ultrafast science evolved from the simple configuration of two-plate vacuum diodes to advanced technologies such as nanotips or photocathodes excited by femtosecond lasers. In a diode either in vacuum or of solid-state, the transit-time limit originating from finite electron mobility has caused spatiotemporal bunch-collapse in ultrafast regime. Here, we show for the first time that abrupt exclusion of transit-phase is a more fundamental origin of the bunch-collapse than the transit-time limit. We found that by significantly extending the cathode-anode gap distance, thereby violating the transit-time limit, the conventional transit-time-related upper frequency barrier in diodes can be removed. Furthermore, we reveal how to control the velocity chirp of bunches leading to ballistic bunch-compression. Demonstration of 0.707 THz-, 46.4 femtosecond-bunches from a 50 μm-wide diode in three-dimensional particle-in-cell simulations shows a way toward simple and compact sources of ultrafast electron bunches for diverse ultrafast sciences.

  20. Bunched and Madm Function Downstream of Tuberous Sclerosis Complex to Regulate the Growth of Intestinal Stem Cells in Drosophila.

    Science.gov (United States)

    Nie, Yingchao; Li, Qi; Amcheslavsky, Alla; Duhart, Juan Carlos; Veraksa, Alexey; Stocker, Hugo; Raftery, Laurel A; Ip, Y Tony

    2015-12-01

    The Drosophila adult midgut contains intestinal stem cells that support homeostasis and repair. We show here that the leucine zipper protein Bunched and the adaptor protein Madm are novel regulators of intestinal stem cells. MARCM mutant clonal analysis and cell type specific RNAi revealed that Bunched and Madm were required within intestinal stem cells for proliferation. Transgenic expression of a tagged Bunched showed a cytoplasmic localization in midgut precursors, and the addition of a nuclear localization signal to Bunched reduced its function to cooperate with Madm to increase intestinal stem cell proliferation. Furthermore, the elevated cell growth and 4EBP phosphorylation phenotypes induced by loss of Tuberous Sclerosis Complex or overexpression of Rheb were suppressed by the loss of Bunched or Madm. Therefore, while the mammalian homolog of Bunched, TSC-22, is able to regulate transcription and suppress cancer cell proliferation, our data suggest the model that Bunched and Madm functionally interact with the TOR pathway in the cytoplasm to regulate the growth and subsequent division of intestinal stem cells.

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

    Science.gov (United States)

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

    2013-04-01

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

  2. 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.

  3. 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

    An unknown major compound, characteristically occurring during processing of oil palm empty fruit bunches was identified with LC-DAD-ESI-MS/MS to be 4-hydroxybenzoic acid. Lignin from oil palm empty fruit bunches contains 4-hydroxybenzoic acid so a tempting conclusion was that the 4-hydroxybenzoic...... 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...

  4. Operational experience on the generation and control of high brightness electron bunch trains at SPARC-LAB

    Science.gov (United States)

    Mostacci, A.; Alesini, D.; Anania, M. P.; Bacci, A.; Bellaveglia, M.; Biagioni, A.; Cardelli, F.; Castellano, Michele; Chiadroni, Enrica; Cianchi, Alessandro; Croia, M.; Di Giovenale, Domenico; Di Pirro, Giampiero; Ferrario, Massimo; Filippi, Francesco; Gallo, Alessandro; Gatti, Giancarlo; Giribono, Anna; Innocenti, L.; Marocchino, A.; Petrarca, M.; Piersanti, L.; Pioli, S.; Pompili, Riccardo; Romeo, Stefano; Rossi, Andrea Renato; Shpakov, V.; Scifo, J.; Vaccarezza, Cristina; Villa, Fabio; Weiwei, L.

    2015-05-01

    Sub-picosecond, high-brightness electron bunch trains are routinely produced at SPARC-LAB via the velocity bunching technique. Such bunch trains can be used to drive multi-color Free Electron Lasers (FELs) and plasma wake field accelerators. In this paper we present recent results at SPARC-LAB on the generation of such beams, highlighting the key points of our scheme. We will discuss also the on-going machine upgrades to allow driving FELs with plasma accelerated beams or with short electron pulses at an increased energy.

  5. 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.

  6. 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.

  7. Wall-Current-Monitor based Ghost and Satellite Bunch Detection in the CERN PS and the LHC Accelerators

    CERN Document Server

    Steinhagen, R J; Belleman, J; Bohl, T; Damerau, H

    2012-01-01

    While most LHC detectors and instrumentation systems are optimised for a nominal bunch spacing of 25 ns, the LHC RF cavities themselves operate at the 10th harmonic of the maximum bunch frequency. Due to the beam production scheme and transfers in the injector chain, part of the nominally ‘empty’ RF buckets may contain particles, referred to as ghost or satellite bunches. These populations must be accurately quantified for high-precision experiments, luminosity calibration and control of parasitic particle encounters at the four LHC interaction points. This contribution summarises the wall-current-monitor based ghost and satellite bunch measurements in CERN’s PS and LHC accelerators. Instrumentation set-up, post-processing and achieved performance are discussed.

  8. 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.

  9. 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.

  10. A linear radiofrequency quadrupole ion trap for the cooling and bunching of radioactive ion beams

    CERN Document Server

    Kellerbauer, A G; Dilling, J; Henry, S; Herfurth, F; Kluge, H J; Lamour, E; Moore, R B; Scheidenberger, C; Schwarz, S; Sikler, G; Szerypo, J

    2002-01-01

    A linear radiofrequency quadrupole ion guide and beam buncher has been installed at the ISOLTRAP mass spectrometry experiment at the ISOLDE facility at CERN. The apparatus is being used as a beam cooling, accumulation, and bunching system. It operates with a buffer gas that cools the injected ions and converts the quasicontinuous 60- keV beam from the ISOLDE facility to 2.5-keV beam pulses with improved normalized transverse emittance. Recent measurements suggest a capture efficiency of the ion guide of up to 40% and a cooling and bunching efficiency of at least 12% which is expected to still be increased. The improved ISOLTRAP setup has so far been used very successfully in three on-line experiments. (12 refs).

  11. Density bunching effects in a laser-driven, near-critical density plasma for ion acceleration

    Science.gov (United States)

    Ettlinger, Oliver; Sahai, Aakash; Hicks, George; Ditter, Emma-Jane; Dover, Nicholas; Chen, Yu-Hsin; Helle, Michael; Gordon, Daniel; Ting, Antonio; Polyanskiy, Mikhail; Pogorelsky, Igor; Babzien, Marcus; Najmudin, Zulfikar

    2016-10-01

    We present work investigating the interaction of relativistic laser pulses with near-critical density gas targets exhibiting pre-plasma scale lengths of several laser wavelengths. Analytical and computational modelling suggest that the interaction dynamics in a low-Z plasma is a direct result of induced density bunching up to the critical surface. In fact, these bunches can themselves become overcritical and experience significant radiation pressure, accelerating ions to higher energies compared to an ``idealised'' plasma slab target. This work will be used to help explain the observation of ion energies exceeding those predicted by radiation pressure driven hole-boring in recent experiments using the TW CO2 laser at the Accelerator Test Facility at Brookhaven National Laboratory.

  12. 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.

  13. High quality electron bunch generation with CO2-laser plasma accelerator

    CERN Document Server

    Zhang, L G; Xu, J C; Ji, L L; Zhang, X M; Wang, W P; Zhao, X Y; Yi, L Q; Yu, Y H; Shi, Y; Xu, T J; Xu, Z Z

    2014-01-01

    CO2 laser-driven electron acceleration is demonstrated with particle-in-cell simulation in low-density plasma. An intense CO2 laser pulse with long wavelength excites wakefield. The bubble behind it has a broad space to sustain a large amount of electrons before reaching its charge saturation limit. A transversely propagating inject pulse is used to induce and control the ambient electron injection. The accelerated electron bunch with total charge up to 10 nC and the average charge per energy interval of more than 0.6 nC/MeV are obtained. Plasma-based electron acceleration driven by intense CO2 laser provides a new potential way to generate high-charge electron bunch with low energy spread, which has broad applications, especially for X-ray generation by table-top FEL and bremsstrahlung.

  14. Microbunching instability in relativistic electron bunches: direct observations of the microstructures using ultrafast YBCO detectors.

    Science.gov (United States)

    Roussel, E; Evain, C; Szwaj, C; Bielawski, S; Raasch, J; Thoma, P; Scheuring, A; Hofherr, M; Ilin, K; Wünsch, S; Siegel, M; Hosaka, M; Yamamoto, N; Takashima, Y; Zen, H; Konomi, T; Adachi, M; Kimura, S; Katoh, M

    2014-08-29

    Relativistic electron bunches circulating in accelerators are subjected to a dynamical instability leading to microstructures at millimeter to centimeter scale. Although this is a well-known fact, direct experimental observations of the structures, or the field that they emit, remained up to now an open problem. Here, we report the direct, shot-by-shot, time-resolved recording of the shapes (including envelope and carrier) of the pulses of coherent synchrotron radiation that are emitted, and that are a "signature" of the electron bunch microstructure. The experiments are performed on the UVSOR-III storage ring, using electrical field sensitive YBa2Cu3O(7-x) thin-film ultrafast detectors. The observed patterns are subjected to permanent drifts, that can be explained from a reasoning in phase space, using macroparticle simulations.

  15. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, J., E-mail: jun.zhu@desy.de [Deutsches Elektronen-Synchrotron, DESY, Hamburg (Germany); Universität Hamburg, Hamburg (Germany); Assmann, R.W.; Dorda, U.; Marchetti, B. [Deutsches Elektronen-Synchrotron, DESY, Hamburg (Germany)

    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.

  17. 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 ...

  18. 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.

  19. 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.

  20. Thomson backscattering diagnostics of nanosecond electron bunches in high space charge regime

    CERN Document Server

    Paroli, B

    2012-01-01

    The intra-beam repulsions play a significant role in determining the performances of free-electron devices when an high brilliance of the beam is required. The transversal and longitudinal spread of the beam, its energy and density are fundamental parameters in any beam experiment and different beam diagnostics are available to measure such parameters. A diagnostic method based on the Thomson backscattering of a laser beam impinging on the particle beam is proposed in this work for the study of nanosecond electron bunches in high space charge regime. This diagnostics, aimed to the measurement of density, energy and energy spread, was set-up in a Malmberg-Penning trap (generally used for the electron/ion confinment) in two different configurations designed to optimize sensitivity, spatial resolution and electron-beam coincidence in space and time. To this purpose an electron bunch (pulse time <4ns), produced by a photocathode source, was preliminary characterized with different electrostatic diagnostics and...

  1. MD1831: Single Bunch Instabilities with Q" and Non-Linear Corrections

    CERN Document Server

    Carver, Lee Robert; De Maria, Riccardo; Li, Kevin Shing Bruce; Amorim, David; Biancacci, Nicolo; Buffat, Xavier; Maclean, Ewen Hamish; Metral, Elias; Lasocha, Kacper; Lefevre, Thibaut; Levens, Tom; Salvant, Benoit; CERN. Geneva. ATS Department

    2017-01-01

    During MD1751, it was observed that both a full single beam and 964 non-colliding bunches in Beam 1 (B1) and Beam 2 (B2) were both stable at the End of Squeeze (EOS) for 0A in the Landau Octupoles. At ß* = 40cm there is also a significant Q" arising from the lattice, as well as uncorrected non-linearities in the Insertion Regions (IRs). Each of these effects could be capable of fully stabilising the beam. This MD made first use of a Q" knob through variation of the Main Sextupoles (MS) by stabilising a single bunch at Flat Top, before showing at EOS that the non-linearities were the main contributors to the beam stability.

  2. Proposal for Single-Bunch Collimator Wakefield Measurements at SLAC ESTB

    CERN Document Server

    Resta-Lopez, J; Faus-Golfe, A; Fuster-Martinez, N; Hast, C; Jones, R M; Latina, A; Pivi, M; Rumolo, G; Schulte, D; Smith, J; Tomas, R

    2012-01-01

    Collimator wakefields in the Beam Delivery System (BDS) of future linear colliders, such as the International Linear Collider (ILC) and the Compact Linear Collider (CLIC), can be an important source of emittance growth and beam jitter amplification, consequently degrading the luminosity. Therefore, a better understanding of collimator wakefield effects is essential to optimise the collimation systems of future linear colliders in order to minimise wakefield effects. In the past, measurements of single-bunch collimator wakefields have been carried out at SLAC with the aim of benchmarking theory, numerical calculations and experiments. Those studies revealed some discrepancies between the measurements and the theoretical models. New experimental tests using available beam test facilities, such as the End Station A Test Beam (ESTB) at SLAC, would help to improve our understanding on collimator wakefields. ESTB will provide the perfect test bed to investigate collimator wakefields for different bunch length condi...

  3. Sensitivity improvement of radio receivers by exploiting an arithmetic pattern in photon bunching noise

    CERN Document Server

    Lieu, Richard

    2016-01-01

    A hierarchy of statistics of increasing sophistication and accuracy is proposed, to exploit an interesting and fundamental arithmetic structure in the photon bunching noise of incoherent light of large photon occupation number, with the purpose of suppressing the noise and rendering a more reliable and unbiased measurement of the light intensity. The method does not require any new hardware, rather it operates at the software level, with the help of high precision computers, to reprocess the intensity time series of the incident light to create a new series with smaller bunching noise coherence length. The ultimate accuracy improvement of this method of flux measurement is limited by the timing resolution of the detector, the precision of the computer in manipulating numbers, and the photon occupation number of the beam (the higher the photon number the better the performance). The principal application is sensitivity enhancement of radio astronomical observations.

  4. 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).

  5. 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 ...

  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. Preparation of activated carbon by microwave heating of langsat (Lansium domesticum) empty fruit bunch waste.

    Science.gov (United States)

    Foo, K Y; Hameed, B H

    2012-07-01

    The feasibility of langsat empty fruit bunch waste for preparation of activated carbon (EFBLAC) by microwave-induced activation was explored. Activation with NaOH at the IR ratio of 1.25, microwave power of 600 W for 6 min produced EFBLAC with a carbon yield of 81.31% and adsorption uptake for MB of 302.48 mg/g. Pore structural analysis, scanning electron microscopy and Fourier transform infrared spectroscopy demonstrated the physical and chemical characteristics of EFBLAC. Equilibrium data were best described by the Langmuir isotherm, with a monolayer adsorption capacity of 402.06 mg/g, and the adsorption kinetics was well fitted to the pseudo-second-order equation. The findings revealed the potential to prepare high quality activated carbon from langsat empty fruit bunch waste by microwave irradiation.

  9. Electro-optical Measurements of Ultrashort 45 MeV Electron Beam Bunches

    CERN Document Server

    Tsang, Thomas; Kowalski, L A; Larsen, R; Lazarus, D M; Nikas, D; Ozben, C; Semertzidis, Y K; Srinivasan-Rao, T

    2000-01-01

    We have measured the temporal duration of 45 MeV picosecond electron beam bunches using a noninvasive electro-optical (EO) technique. The amplitude of the EO modulation was found to increase linearly with electron beam charge and decrease inversely with distance from the electron beam. The risetime of the temporal signal was limited by our detection system to ~70ps. The EO signal due to ionization caused by the electrons traversing the EO crystal was also observed. It has a distinctively long decay time constant and signal polarity opposite to that due to the field induced by the electron beam. The electro-optical technique may be ideal for the measurement of bunch length of femtosecond, relativistic, high energy, charged, particle beams.

  10. 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.

  11. 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.

  12. Bacterial Community Structure and Biochemical Changes Associated With Composting of Lignocellulosic Oil Palm Empty Fruit Bunch

    OpenAIRE

    Mohd Huzairi Mohd Zainudin; Mohd Ali Hassan,; Umi Kalsom Md Shah; Norhani Abdullah; Mitsunori Tokura; Hisashi Yasueda; Yoshihito Shirai; Kenji Sakai; Azhari Samsu Baharuddin

    2013-01-01

    Bacterial community structure and biochemical changes during the composting of lignocellulosic oil palm empty bunch (EFB) and palm oil mill effluent (POME) anaerobic sludge were studied by examining the succession of the bacterial community and its association with changes in lignocellulosic components by denaturing gradient gel electrophoresis (DGGE) and the 16S rRNA gene clone library. During composting, a major reduction in cellulose after 10 days from 50% to 19% and the carbon content fro...

  13. 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.

  14. 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.

  15. Status of non-destructive bunch length measurement based on coherent Cherenkov radiation

    CERN Document Server

    Zhang, Jianbing; Yu, Tiemin; Deng, Haixiao; Shkitov, Dmitry; Shevelev, Mikhail; Naumenko, Gennady; Potylitsyn, Alexander

    2013-01-01

    As a novel non-destructive bunch length diagnostic of the electron beam, an experimental observation of the coherent Cherenkov radiation generated from a dielectric caesium iodide crystal with large spectral dispersion was proposed for the 30MeV femtosecond linear accelerator at Shanghai Institute of Applied Physics (SINAP). In this paper, the theoretical design, the experimental setup, the terahertz optics, the first angular distribution observations of the coherent Cherenkov radiation, and the future plans are presented.

  16. Pretreatment of empty fruit bunch from oil palm for fuel ethanol production and proposed biorefinery process.

    Science.gov (United States)

    Tan, Liping; Yu, Yongcheng; Li, Xuezhi; Zhao, Jian; Qu, Yinbo; Choo, Yuen May; Loh, Soh Kheang

    2013-05-01

    This study evaluates the effects of some pretreatment processes to improve the enzymatic hydrolysis of oil palm empty fruit bunch (EFB) for ethanol production. The experimental results show that the bisulfite pretreatment was practical for EFB pretreatment. Moreover, the optimum pretreatment conditions of the bisulfite pretreatment (180 °C, 30 min, 8% NaHSO3, 1% H2SO4) were identified. In the experiments, a biorefinery process of EFB was proposed to produce ethanol, xylose products, and lignosulfonates.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Electron Cloud Cyclotron Resonances in the Presence of a Short-bunch-length Relativistic Beam

    Energy Technology Data Exchange (ETDEWEB)

    Celata, C.M.; Furman, Miguel A.; Vay, J.-L.; Yu, Jennifer W.

    2008-09-02

    Computer simulations using the 2D code"POSINST" were used to study the formation of the electron cloud in the wiggler section of the positron damping ring of the International Linear Collider. In order to simulate an x-y slice of the wiggler (i.e., a slice perpendicular to the beam velocity), each simulation assumed a constant vertical magnetic field. At values of the magnetic field where the cyclotron frequency was an integral multiple of the bunch frequency, and where the field strength was less than approximately 0.6 T, equilibrium average electron densities were up to three times the density found at other neighboring field values. Effects of this resonance between the bunch and cyclotron frequency are expected to be non-negligible when the beam bunch length is much less than the product of the electron cyclotron period and the beam velocity, for a beam moving at v~;;c. Details of the dynamics of the resonance are described.

  2. 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.

  3. 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.

  4. Double and triple-harmonic RF buckets and their use for bunch squeezing in AGS

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-08-24

    For the past several years we have merged bunches in AGS in order to achieve the desired intensity per bunch prior to injection into RHIC. The merging is done on a at porch at or above AGS injection energy. Because the merges involve the reduction of the RF harmonic number by a factor of 2 (for a 2 to 1 merge) and then a factor of 3 (for a 3 to 1 merge), one requires RF frequencies 6hfs, 3hfs, 2hfs and hfs, where fs is the revolution frequency on the porch and h = 4 is the fundamental harmonic number. The standard AGS RF cavities cannot operate at the lowest frequencies 2hfs and hfs; these are provided by two modi ed cavities. Upon completion of the merges, the bunches are sitting in harmonic h buckets. In order to be accelerated they need to be squeezed into harmonic 3h buckets. This is accomplished by producing a double-harmonic bucket in which harmonics h and 2h act in concert, and then a triple-harmonic bucket in which harmonics h, 2h, and 3h act in concert. Simulations have shown that the squeeze presents an acceptance bottleneck which limits the longitudinal emittance that can be put into the harmonic 3h bucket.

  5. 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...

  6. 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.

  7. Monte Carlo Mean Field Treatment of Microbunching Instability in the FERMI@Elettra First Bunch Compressor

    Energy Technology Data Exchange (ETDEWEB)

    Bassi, G.; /Liverpool U. /Cockroft Inst.; Ellison, J.A.; Heinemann, K.; /New Mexico U.; Warnock, R.; /SLAC

    2009-05-07

    Bunch compressors, designed to increase the peak current, can lead to a microbunching instability with detrimental effects on the beam quality. This is a major concern for free electron lasers (FELs) where very bright electron beams are required, i.e. beams with low emittance and energy spread. In this paper, we apply our self-consistent, parallel solver to study the microbunching instability in the first bunch compressor system of FERMI{at}Elettra. Our basic model is a 2D Vlasov-Maxwell system. We treat the beam evolution through a bunch compressor using our Monte Carlo mean field approximation. We randomly generate N points from an initial phase space density. We then calculate the charge density using a smooth density estimation procedure, from statistics, based on Fourier series. The electric and magnetic fields are calculated from the smooth charge/current density using a novel field formula that avoids singularities by using the retarded time as a variable of integration. The points are then moved forward in small time steps using the beam frame equations of motion, with the fields frozen during a time step, and a new charge density is determined using our density estimation procedure. We try to choose N large enough so that the charge density is a good approximation to the density that would be obtained from solving the 2D Vlasov-Maxwell system exactly. We call this method the Monte Carlo Particle (MCP) method.

  8. 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.

  9. Transverse coupled-bunch instability thresholds in the presence of a harmonic-cavity-flattened rf potential

    Science.gov (United States)

    Cullinan, F. J.; Nagaoka, R.; Skripka, G.; Tavares, P. F.

    2016-12-01

    A small vacuum chamber aperture is a present trend in the design of future synchrotron light sources. This leads to a large resistive-wall impedance that can drive coupled-bunch instabilities. Another trend is the use of passively driven cavities at a harmonic of the main radio frequency to lengthen the electron bunches in order to increase the Touschek lifetime and reduce emittance blowup due to intrabeam scattering. In some cases, the harmonic cavities may be tuned to fulfill the flat potential condition. With this condition met, it has been predicted in simulation that the threshold current for coupled-bunch resistive-wall instabilities is much higher than with no bunch lengthening at all. In this paper, the features of a bunch in the flat potential that would contribute toward this stabilization are identified and discussed. The threshold currents for these instabilities are estimated for the MAX IV 3 GeV storage ring at different values of chromaticity using macroparticle simulations in the time domain and, within the limits of the existing theory, frequency domain calculations. By comparing the results from these two methods and analyzing the spectra of the dominant head-tail modes, the impact of each of the distinguishing features of a bunch in the flat potential can be explained and quantified in terms of the change in threshold current. It is found that, above a certain chromaticity, the threshold current is determined by the radial structure of the zeroth-order head-tail mode. This happens at a lower chromaticity if the bunch length is longer.

  10. 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.

  11. 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.

  12. 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.

  13. 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...

  14. 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...

  15. Generation of femtosecond bunch trains using a longitudinal-to-transverse phase space exchange technique

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Yin-e; /Fermilab; Piot, Philippe; /Fermilab /Northern Illinois U.

    2008-10-01

    We demonstrate analytically and via numerical simulations, how a longitudinal-to-transverse phase space manipulation can be used to produce a train of femtosecond electron bunches. The technique uses an incoming transversely-modulated electron beam obtained via destructive (e.g. using a multislits mask) methods. A transverse-to-longitudinal exchanger is used to map this transverse modulation into a temporal modulation. Limitation of the proposed method and scalability to the femtosecond regime are analyzed analytically and with the help of numerical simulation. Finally, a proof-of-principle experiment is discussed in the context of the Fermilab's A0 photoinjector.

  16. Enhanced coherent emission of terahertz radiation by energy-phase correlation in a bunched electron beam.

    Science.gov (United States)

    Doria, A; Gallerano, G P; Giovenale, E; Messina, G; Spassovsky, I

    2004-12-31

    We report the first observation of enhanced coherent emission of terahertz radiation in a compact free electron laser. A radio-frequency (rf) modulated electron beam is passed through a magnetic undulator emitting coherent radiation at harmonics of the rf with a phase which depends on the electron drift velocity. A proper correlation between the energy and phase distributions of the electrons in the bunch has been exploited to lock in phase the radiated field, resulting in over 1 order of magnitude enhancement of the coherent emission.

  17. Effectiveness of rf phase modulation for increasing bunch length in electron storage rings

    Science.gov (United States)

    Orsini; Mosnier

    2000-04-01

    Aiming at increasing the apparent bunch length and hence the beam lifetime in electron storage rings, rf phase modulation near one parametric resonance has been experimentally investigated. Since the possible benefit of this technique depends greatly on the ring parameters, we studied the effect of such a modulation for different rf parameters on the longitudinal emittance. Theoretical predictions and results of simulations are compared and discussed. It is shown that synchrotron radiation tends to spoil the parametric resonance. In particular, a criterion for island survival has been found.

  18. Vacuum electron acceleration and bunch compression by a flat-top laser beam.

    Science.gov (United States)

    Wang, W; Wang, P X; Ho, Y K; Kong, Q; Gu, Y; Wang, S J

    2007-09-01

    The field intensity distribution and phase velocity characteristics of a flat-top laser beam are analyzed and discussed. The dynamics of electron acceleration in this kind of beam are investigated using three-dimensional test particle simulations. Compared with the standard (i.e., TEM(00) mode) Gaussian beam, a flat-top laser beam has a stronger longitudinal electric field and a larger diffraction angle. These characteristics make it easier for electrons to be trapped and accelerated by the beam. With a flat-top shape, the laser beam is also applicable to the acceleration of low energy electron and bunch compression.

  19. 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.

  20. Rf stability, control and bunch lengthening in electron synchrotron storage rings

    Energy Technology Data Exchange (ETDEWEB)

    Wachtel, J.M.

    1989-09-01

    A self-consistent theory for nonlinear longitudinal particle motion and rf cavity excitation in a high energy electron storage ring is developed. Coupled first order equations for the motion of an arbitrary number of particles and for the field in several rf cavities are given in the form used in control system theory. Stochastic quantum excitation of synchrotron motion is included, as are the effects of rf control system corrections. Results of computations for double cavity bunch lengthening are given. 11 refs., 4 figs., 1 tab.

  1. Improvement on a Michelson interferometer for bunch length measurement of a femtosecond accelerator

    Institute of Scientific and Technical Information of China (English)

    LIN Xuling; ZHANG Jianbing; BEI Hua; DAI Zhimin

    2009-01-01

    Based on the femtosecond accelerator facility at Shanghai Institute of Applied Physics (SINAP),a conventional far-infrared Michelson interferometer was built to measure the bunch length by means of optical autocorrelation.However,according to the preliminary experiment result,the resolution of interferometer is not good enough,because the mirror-driving mechanism makes the moving mirror tend to tilt or wobble as it retards.Considering of the allowable errors,we calculate the maximum allowable titling angle of the moving mirror,and discuss the alignment plan in this paper.

  2. Particle self-bunching in the Schwinger effect in spacetime-dependent electric fields.

    Science.gov (United States)

    Hebenstreit, F; Alkofer, R; Gies, H

    2011-10-28

    Nonperturbative electron-positron pair creation (the Schwinger effect) is studied based on the Dirac-Heisenberg-Wigner formalism in 1+1 dimensions. An ab initio calculation of the Schwinger effect in the presence of a simple space- and time-dependent electric field pulse is performed for the first time, allowing for the calculation of the time evolution of observable quantities such as the charge density, the particle number density or the total number of created particles. We predict a new self-bunching effect of charges in phase space due to the spatial and temporal structure of the pulse.

  3. Utilization of palm empty fruit bunch for the production of biodiesel from Jatropha curcas oil.

    Science.gov (United States)

    Yaakob, Zahira; Sukarman, Irwan Sukma Bin; Narayanan, Binitha; Abdullah, Siti Rozaimah Sheikh; Ismail, Manal

    2012-01-01

    Transesterification reaction of Jatropha curcas oil with methanol was carried out in the presence of ash generated from Palm empty fruit bunch (EFB) in a heterogeneous catalyzed process. The ash was doped with KOH by impregnation to achieve a potassium level of 20 wt.%. Under optimum conditions for the EFB-catalyzed (65 °C, oil/methanol ratio of 15, 90 min, 20 wt.% EFB ash catalyst) and the KOH-EFB-catalyzed reactions (65 °C, oil/methanol ratio of 15, 45 min, 15 wt.% of KOH doped EFB ash), biodiesel (>98%) with specifications higher than those stipulated by European biodiesel quality standard EN 14214 was obtained.

  4. Isolation of Nanocrystalline Cellulose from oil palm empty fruit bunch – A response surface methodology study

    Directory of Open Access Journals (Sweden)

    Song Yee Kai

    2016-01-01

    Full Text Available The research work studied the extraction of Nano Crystalline Cellulose (NCC from oil palm empty fruit bunch (EFB, with aid of Response Surface Methodology (RSM. Particle size analysis using Malvern Zetasizer had confirmed the extracted NCC fall within the desired nano scaled range. The impact of three input parameters, namely concentration of NaOH solution during alkaline treatment, concentration of H2SO4 solution during acid hydrolysis, and duration for acid hydrolysis on NCC particle were investigated. From ANOVA study, it had suggested that the current RSM model is significant to interpret the interaction among the all three input parameters.

  5. Drying Pre-treatment on Empty Fruit Whole Bunches of Oil Palm Wastes

    Science.gov (United States)

    Khalib, N. Che; Abdullah, N.; Sulaiman, F.

    2010-07-01

    This study is focused on the drying pre-treatment on whole empty fruit bunches [EFB] oil palm wastes. The drying process of whole EFB wastes by conventional method is investigated using the conventional oven in order to obtain less than 10 mf wt % moisture content. Normally, the biomass is dried to less than 10 mf wt % in most laboratory experiments and commercial processes for thermal conversion technologies such as pyrolysis. The result shows that the moisture content of EFB of less than 10 mf wt % is achieved after 29 hours of drying process.

  6. 束团序列发射的相干同步辐射强度数值计算%Numerical Calculation on Coherent Synchrotron Radiation Intensity Due to Inter-Bunch Interference in the Bunch Train

    Institute of Scientific and Technical Information of China (English)

    朱俊彪; 张国庆; 李永贵; 谢家麟

    2001-01-01

    提出一个新颖的射频电子束团序列在偏转或者摇摆磁场中发射的相干同步辐射相干迭加导致辐射增强的理论模型,并基此分析和计算了利用BFEL装置的30MeV射频直线加速器产生的电子束团序列发射的相干辐射增强效应. 由讨论可知,不同的束团产生的相干同步辐射之间存在相干性源于束团间的相干性;这种束团间的相干性引起的辐射增强迭加在单个束团产生的相干辐射功率谱上;随着波长的增长,这种辐射增强呈现规则的高速振荡效应;束团间相干性引起的强度增强近似约为宏脉冲内所含束团数的平方. 最后提出利用所设计的毫米波Michelson干涉仪检测BFEL装置的电子束团序列的相干性的实验设想.%A novel model for the inter-bunch interference in a bunch train is presented where a train of electron bunches passing through a bending or undulator magnetic field is considered as a moving multi-slit diffraction array from which multi beams of coherent radiation emitted with definite phase difference. Based on this model,interference among multi-beams of coherent synchrotron radiation emitted from consecutive bunches accelerated by a 30 MeV RF-Linac at BFEL is analyzed and numerically calculated. From the discussions it is shown that: 1. Rapidly oscillating radiation enhancement due to inter-bunch interference is overlapped on the single bunch power spectrum;2. Such radiation enhancement consists of series of spectrum lines corresponding to harmonics of the fundamental of RF-Linac;3. Main maximum positions are determined by the “diffraction condition”;4. Intensity enhancement is about as high as the number of bunches in a macropulse;5. The axially measured radiation frequency is lower than the offaxis one. Experimental design to measure interference from separate bunches at the BFEL Linac with the developed mm-wave Michelson interferometer is presented.

  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. 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.

  10. 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.

  11. Development of a Bunch Frequency Monitor for the Preliminary Phase of the CLIC Test Facility CTF3

    CERN Document Server

    Caspers, Friedhelm; Ferrari, A; Rinolfi, Louis; Royer, P; Rydberg, A; Tecker, F A

    2003-01-01

    In the framework of the CLIC RF power source studies, the feasibility of the electron bunch train combination by injection with RF deflectors into an isochronous ring has been successfully demonstrated in the preliminary phase of CTF3. A new method, based on beam frequency spectrum analysis, was experimented to monitor this scheme. A coaxial pick-up and its read-out electronics were designed and mounted in the CTF3 ring to allow comparison of the amplitudes of five harmonics of the fundamental beam frequency (3 GHz) while combining the bunch trains. The commissioning of the monitor was a successful proof of principle for this new method, despite the short length of the bunch trains and the presence of parasitic signals associated to high-order waveguide modes propagating with the beam inside the pipe.

  12. 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...

  13. 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...

  14. 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...

  15. Beam transfer functions for relativistic proton bunches with beam–beam interaction

    Energy Technology Data Exchange (ETDEWEB)

    Görgen, P., E-mail: goergen@temf.tu-darmstadt.de [Institut für Theorie Elektromagnetischer Felder (TEMF), Technische Universität Darmstadt, Schloßgartenstr. 8 64289 Darmstadt (Germany); Boine-Frankenheim, O. [Institut für Theorie Elektromagnetischer Felder (TEMF), Technische Universität Darmstadt, Schloßgartenstr. 8 64289 Darmstadt (Germany); Fischer, W. [Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2015-03-21

    We present a method for the recovery of the transverse tune spread directly from the beam transfer function (BTF). The model is applicable for coasting beams and bunched beams at high energy with a tune spread from transverse nonlinearities induced by the beam–beam effect or by an electron lens. Other sources of tune spread can be added. A method for the recovery of the incoherent tune spread without prior knowledge of the nonlinearity is presented. The approach is based on the analytic model for BTFs of coasting beams, which agrees very well with simulations results for bunched beams at relativistic energies with typically low synchrotron tune. A priori the presented tune spread recovery method is usable only in the absence of coherent modes, but additional simulation data shows its applicability even in the presence of coherent beam–beam modes. Finally agreement of both the analytic and simulation models with measurement data obtained at RHIC is presented. The proposed method successfully recovers the tune spread from analytic, simulated and measured BTF.

  16. 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.

  17. 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.

  18. Remote control of a streak camera for real time bunch size measurement in LEP

    CERN Document Server

    Burns, A J; De Vries, J C

    1995-01-01

    A double sweep streak camera, built by industry according to CERN specifications, has been used for a number of years to provide real time three-dimensional measurements of bunches in LEP, by means of a dedicated synchrotron light source. Originally requiring local manipulation in an underground lab close to the LEP tunnel, the camera can now be fully operated via the control system network. Control functions, such as the adjustment of lens and mirror positions, the selection of camera weep speeds, and the setting of 12 ps resolution trigger timing, are handled by various networked VME systems, as is real time image processing. Bunch dimension averages are transferred every few seconds via the control system to the LEP measurement database, and a dedicated high bandwidth video transmission allows the streak camera images and processed results to be viewed in real time (at 25 Hz) in the LEP control room. Feedback control loops for light intensity, trigger timing and image tracking allow the setup to provide us...

  19. 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.)

  20. Single bunch injection system for storage ring FEL using an rf photoinjector

    Science.gov (United States)

    O'Shea, P. G.; Lancaster, J. A.; Madey, J. M. J.; Sachtschale, R.; Jones, R.

    1997-05-01

    RF photoinjectors have gained acceptance as the source of choice for high-brightness electron accelerators, but have been quite expensive to build and difficult to operate. In this paper we describe the successful operation of an inexpensive, simple and reliable rf photoinjector suitable for single bunch injection into storage rings. For optimum storage ring FEL and Compton Backscatter performance, we require that the electrons be injected to specified ring rf buckets and no others. The injector-linac electron gun is a single-cell s-band rf gun with a LaB6 cathode. The gun is followed by an a-magnet momentum filter and buncher. The LaB6 cathode can be operated in a pure thermionic mode, a laser switched photoemission mode, or in a combined mode. The laser is a near-UV TEA nitrogen laser with a 600 ps pulse, and 0-50 Hz repetition rate. We routinely inject 0.1 nC bunches at 270 MeV. The ratio of charge in the primary ring bucket to that in the other buckets is better than 1000.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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...

  8. The beam bunching and transport system of the Argonne positive ion injector

    Energy Technology Data Exchange (ETDEWEB)

    Den Hartog, P.K.; Bogaty, J.M.; Bollinger, L.M.; Clifft, B.E.; Pardo, R.C.; Shepard, K.W.

    1989-01-01

    A new positive ion injector (PII) is currently under construction at Argonne that will replace the existing 9-MV tandem electrostatic accelerator as an injector into ATLAS. It consists of an electron-cyclotron resonance-ion source on a 350-kV platform injecting into a superconducting linac optimized for very slow (..beta.. less than or equal to .007 c) ions. This combination can potentially produce even higher quality heavy-ion beams than are currently available from the tandem since the emittance growth within the linac is largely determined by the quality of the bunching and beam transport. The system we have implemented uses a two-stage bunching system, composed of a 4-harmonic gridded buncher located on the ECR high-voltage platform and a room temperature spiral-loaded buncher of novel design. A sinusoidal beam chopper is used for removal of tails. The beam transport is designed to provide mass resolution of M/..delta..M > 250 and a doubly-isochronous beamline is used to minimize time spread due to path length differences. 4 refs., 2 figs.

  9. 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.

  10. 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.

  11. 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.

  12. 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....

  13. 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.

  14. External injection and acceleration of electron bunch in front of the plasma wakefield produced by a periodic chirped laser pulse

    Science.gov (United States)

    Eslami, Esmaeil; Afhami, Saeedeh

    2017-01-01

    Herein, we present the analytical results on the behavior of the electron bunch injected in front of the plasma wakefield produced by a chirped laser pulse. In particular, a periodic chirped pulse may produce an ultra-relativistic electron bunch with a relatively small energy spread. The electrons are trapped near the region of the first accelerating maximum of the wakefield and are compressed in both the longitudinal and transverse directions (betatron oscillation). Our results are in good agreement with the one-dimensional results recently published.

  15. Bunch stabilization using rf phase modulation in the Intense Pulse Neutron Source (IPNS) Rapid Cycling Synchrotron (RCS).

    Energy Technology Data Exchange (ETDEWEB)

    Brumwell, F. R.; Dooling, J. C.; McMichael, G. E.

    1999-09-01

    Phase modulation (PM) is used to increase the current limit in the IPNS RCS. A device referred to as a scrambler introduces a small oscillating phase between the two RCS rf cavities at approximately twice the synchrotrons frequency, f{sub s}. The modulation introduced by the scrambler generates longitudinal oscillations in the bunch at 2f{sub s}. Modulations in the bunch are also observed transversely indicating a coupling between longitudinal and transverse motion. Comparing PM with amplitude modulation (AM), coupling to the beam is roughly equivalent at 2f{sub s}.

  16. Simulation Results of a Feedback Control System to Damp Electron Cloud Single-Bunch Transverse Instabilities in the CERN SPS

    CERN Document Server

    Secondo, R; Venturini, M; Fox, J D; Rivetta, C H; Höfle, W

    2011-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Kluge, T., E-mail: t.kluge@hzdr.de; 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).

  18. 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

  19. Evaluation of Bunch Protectors for Preventing Insect Infestation and Preserving Yield and Fruit Quality of Dates, Phoenix dactylifera L.

    Science.gov (United States)

    Perring, Thomas M; Nay, Justin E

    2015-04-01

    In experiments comparing conventional date paper wraps with polyester mesh bags, date bunches enclosed in polyester mesh bags had lower insect infestations than dates covered by paper wraps. Carob moth, Ectomyelois ceratoniae (Zeller), infestations of marketable fruit were significantly lower for mesh bags (0.6-3.1%) compared with paper wraps (8.5-15.5%). Other fruit pests [raisin moth, Cadra figulilella (Gregson), and beetles in the family Nitidulidae] were less common than carob moth, and infestation by these insects was consistently lower in fruit protected by mesh bags. Date bunches in mesh bag treatments had a 21-46% net increase in marketable date fruit owing to the fact that the bags prevented marketable dates from falling to the garden floor. The number of abscised kimri fruit was higher in the mesh bag treatment than the paper wrap treatment, yet there were no differences in the incidences of other fruit maladies (black nose, fruit with fungi, shriveled fruit, abscised khalal fruit, infertile fruit, and nonripe fruit). Bunch sanitation, used just prior to bagging and wrapping dates, successfully removed abscised kimri fruit from bunches, which resulted in a significantly lower number of cull dates from one garden, but this response was not present at a second garden. These studies show that mesh bags should be included in an integrated pest management program on dates.

  20. 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...

  1. Longitudinal impedance monitoring in the SPS with single short bunches at 26 GeV/c (RF on)

    CERN Document Server

    Bohl, T; Shaposhnikova, E; CERN. Geneva. AB Department

    2008-01-01

    In the course of monitoring the low frequency impedance of the SPS over the years usually the quadrupole frequency shift as a function of intensity is measured with single bunches at 26 GeV/c with RF on using the peak detected signal. The additional acquisition of longitudinal bunch profiles allows the evaluation of various parameters of the injected beam, details of its quadrupole oscillation and the evolution of the bunch length as a function of time. Data acquired between 1999 and 2007 will be analysed in this respect. It will be shown that the bunch length data at 600 ms indicates clearly the effect of the SPS impedance reduction programme realised in 2000/2001 and that from then on the absolute value of the quadrupole frequency shift shows a tendency to increase over the years, indicating an impedance increase. However, it does not allow to monitor unambiguously the changes from one year to the next. The reason that the quadrupole frequency shift is not very well determined is attributed to the lack of r...

  2. 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.

  3. Electron identification measurements in ATLAS using $\\sqrt{s}$ = 13 TeV data with 50 ns bunch spacing

    CERN Document Server

    The ATLAS collaboration

    2015-01-01

    This document gives a brief description of early measurements of identification efficiencies of central electrons using proton-proton collision data at $\\sqrt{s} = $13 TeV with 50 ns bunch spacing. The data were collected with the ATLAS detector in 2015 and correspond to an integrated luminosity of $\\int$Ldt = 85 pb$^{-1}$.

  4. 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.)

  5. Application of Metal-Semiconductor-Metal (MSM) Photodetectors for Transverse and Longitudinal Intra-Bunch Beam Diagnostics

    CERN Document Server

    Steinhagen, R J; Boland, M J; Lucas, T G; Rassool, R P

    2013-01-01

    The performance reach of modern accelerators is often governed by the ability to reliably measure and control the beam stability. In high-brightness lepton and high-energy hadron accelerators, the use of optical diagnostic techniques is becoming more widespread as the required bandwidth, resolution and high RF beam power level involved limit the use of traditional electro-magnetic RF pick-up based methods. This contribution discusses the use of fibre-coupled ultra-fast Metal-Semiconductor-Metal Photodetectors (MSM-PD) as an alternative, dependablemeans to measure signals derived from electro-optical and synchrotron-light based diagnostics systems. It describes the beam studies performed at CERN’s CLIC Test Facility (CTF3) and the Australian Synchrotron to assess the feasibility of this technology as a robust, wide-band and sensitive technique for measuring transverse intra-bunch and bunch-by-bunch beam oscillations, longitudinal beam profiles, un-bunched beam population and beam-halo profiles. The amplifica...

  6. On the production of flat electron bunches for laser wake field acceleration

    CERN Document Server

    Kando, M; Kotaki, H; Koga, J; Bulanov, S V; Tajima, T; Chao, A; Pitthan, R; Schüler, K P; Zhidkov, A G; Nemoto, K

    2006-01-01

    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 focus...

  7. Nano-scale electron bunching in laser-triggered ionization injection in plasma accelerators

    CERN Document Server

    Xu, X L; Li, F; Wan, Y; Wu, Y P; Hua, J F; Pai, C -H; Lu, W; An, W; Yu, P; Mori, W B; Joshi, C

    2015-01-01

    Ionization injection is attractive as a controllable injection scheme for generating high quality electron beams using plasma-based wakefield acceleration. Due to the phase dependent tunneling ionization rate and the trapping dynamics within a nonlinear wake, the discrete injection of electrons within the wake is nonlinearly mapped to discrete final phase space structure of the beam at the location where the electrons are trapped. This phenomenon is theoretically analyzed and examined by three-dimensional particle-in-cell simulations which show that three dimensional effects limit the wave number of the modulation to between $> 2k_0$ and about $5k_0$, where $k_0$ is the wavenumber of the injection laser. Such a nano-scale bunched beam can be diagnosed through coherent transition radiation upon its exit from the plasma and may find use in generating high-power ultraviolet radiation upon passage through a resonant undulator.

  8. Steam explosion pretreatment of oil palm empty fruit bunches (EFB) using autocatalytic hydrolysis: A biorefinery approach.

    Science.gov (United States)

    Medina, Jesus David Coral; Woiciechowski, Adenise; Zandona Filho, Arion; Nigam, Poonam Singh; Ramos, Luiz Pereira; Soccol, Carlos Ricardo

    2016-01-01

    The oil palm empty fruit bunches (EFB) are an attractive source of carbon for the production of biochemical products, therefore, the aim of this work is to analyze the effect of the steam explosion (SE) pretreatment under autocatalytic conditions on EFB using a full experimental design. Temperature and reaction time were the operational variables studied. The EFB treated at 195°C for 6 min showed an increase of 34.69% in glycan (mostly cellulose), and a reduction of 68.12% in hemicelluloses, with increased enzymatic digestibility to 33% producing 4.2 g L(-1) of glucose. Scanning electron micrographs of the steam treated EFB exhibited surface erosion and an increased fiber porosity. Fourier transform infrared spectroscopy showed the solubilization of hemicellulose and modification of cellulose in treated EFB.

  9. Single and Multi-bunch End-to-end Tracking in the LHeC

    CERN Document Server

    Pellegrini, D; Latina, A; Schulte, D

    2015-01-01

    The LHeC study aims at delivering an electron beam for collision with the LHC proton beam. The current base- line design consists of a multi-pass superconductive energy- recovery linac operating in a continuous wave mode. The high current beam ($\\sim$ 100 mA) in the linacs excites long- range wake-fields between bunches of different turns, which induce instabilities and might cause beam losses. PLACET2, a novel version of the tracking code PLACET, capable to handle recirculation and time dependencies, has been em- ployed to perform the first LHeC end-to-end tracking. The impact of long-range wake-fields, synchrotron radiation, and beam-beam effects has been assessed. The simulation results and recent improvements in the lattice design are presented and discussed in this paper.

  10. Attosecond Control of Relativistic Electron Bunches using Two-Colour Fields

    CERN Document Server

    Yeung, M; Bierbach, J; Li, L; Eckner, E; Kuschel, S; Woldegeorgis, A; Rödel, C; Sävert, A; Paulus, G G; Coughlan, M; Dromey, B; Zepf, M

    2016-01-01

    Energy coupling during relativistically intense laser-matter interactions is encoded in the attosecond motion of strongly driven electrons at the pre-formed plasma-vacuum boundary. Studying and controlling this motion can reveal details about the microscopic processes that govern a vast array of light-matter interaction physics and applications. These include research areas right at the forefront of extreme laser-plasma science such as laser-driven ion acceleration1, bright attosecond pulse generation2,3 and efficient energy coupling for the generation and study of warm dense matter4. Here we demonstrate attosecond control over the trajectories of relativistic electron bunches formed during such interactions by studying the emission of extreme ultraviolet (XUV) harmonic radiation. We describe how the precise addition of a second laser beam operating at the second harmonic of the driving laser pulse can significantly transform the interaction by modifying the accelerating potential provided by the fundamental ...

  11. Modelling and Studies for a Wideband Feedback System for Mitigation of Transverse Single Bunch Instabilities

    CERN Document Server

    Li, K S B; Rumolo, G; Cesaratto, J; Dusatko, J; Fox, J; Pivi, M; Pollock, K; Rivetta, C; Turgut, O

    2013-01-01

    As part of the LHC Injector Upgrade (LIU) Project [1], a wideband feedback system is under study for mitigation of coherent single bunch instabilities. This type of system may provide a generic way of shifting the instability threshold to regions that are currently inaccessible, thus, boosting the brightness of future beams. To study the effectiveness of such systems, a numerical model has been developed that constitutes a realistic feedback system including real transfer functions for pickup and kicker, realistic N-tap FIR and IIR filters as well as noise and saturation effects. Simulations of SPS cases have been performed with HEADTAIL to evaluate the feedback effectiveness in the presence of transverse mode coupling and electron clouds. Some results are presented addressing bandwidth limitations and amplifier power requirements.

  12. Two mode photon bunching effect as witness of quantum criticality in circuit QED

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    We suggest a scheme to probe critical phenomena at a quantum phase transition (QPT) using the quantum correlation of two photonic modes simultaneously coupled to a critical system. As an experimentally accessible physical implementation,a circuit QED system is formed by a capacitively coupled Josephson junction qubit array interacting with one superconducting transmission line resonator (TLR). It realizes an Ising chain in the transverse field (ICTF) which interacts with the two magnetic modes propagating in the TLR. We demonstrate that in the vicinity of criticality the originally independent fields tend to display photon bunching effects due to their interaction with the ICTF. Thus,the occurrence of the QPT is reflected by the quantum characteristics of the photonic fields.

  13. Two mode photon bunching effect as witness of quantum criticality in circuit QED

    Institute of Scientific and Technical Information of China (English)

    AI Qing; WANG YingDan; LONG GuiLu; SUN ChangPu

    2009-01-01

    We suggest a scheme to probe critical phenomena at a quantum phase transition (OPT) using the quantum correlation of two photonic modes simultaneously coupled to a critical system. As an experimentally accessible physical implementation, a circuit QED system is formed by a capsciUvely coupled Josephson junction qubit array interacting with one superconducting transmission line resonator (TLR). It realizes an Ising chain in the transverse field (ICTF) which interacts with the two magnetic modes propagating in the TLR. We demonstrate that in the vicinity of criticality the originally independent fields tend to display photon bunching effects due to their interaction with the ICTF. Thus,the occurrence of the QPT is reflected by the quantum characteristics of the photonic fields.

  14. Nanoscale Electron Bunching in Laser-Triggered Ionization Injection in Plasma Accelerators

    Science.gov (United States)

    Xu, X. L.; Pai, C.-H.; Zhang, C. J.; Li, F.; Wan, Y.; Wu, Y. P.; Hua, J. F.; Lu, W.; An, W.; Yu, P.; Joshi, C.; Mori, W. B.

    2016-07-01

    Ionization injection is attractive as a controllable injection scheme for generating high quality electron beams using plasma-based wakefield acceleration. Because of the phase-dependent tunneling ionization rate and the trapping dynamics within a nonlinear wake, the discrete injection of electrons within the wake is nonlinearly mapped to a discrete final phase space structure of the beam at the location where the electrons are trapped. This phenomenon is theoretically analyzed and examined by three-dimensional particle-in-cell simulations which show that three-dimensional effects limit the wave number of the modulation to between >2 k0 and about 5 k0, where k0 is the wave number of the injection laser. Such a nanoscale bunched beam can be diagnosed by and used to generate coherent transition radiation and may find use in generating high-power ultraviolet radiation upon passage through a resonant undulator.

  15. Effect of bunching of cilia and their interplay on muco-ciliary transport.

    Science.gov (United States)

    Roy, Yagnaseni; Sivathanu, Vivek; Das, Sarit K

    2013-11-01

    Cilia are hair-like organelles projecting from a eukaryotic cell, used either for locomotion or as sensors. Cilia commonly occur in patches. To take this into consideration, we represent cilia in multiple patches, instead of the conventional 'dense mat' representation. We focus on the combined action and interplay of these patches. The effects of varying the frequency, spacing and phase lag of the beating of one cilia bunch with respect to the beating of adjacent patches are studied. We model the Airway Surface Liquid (ASL) as a three-layer structure. The possibility of an optimum frequency of beating is noted and the change of mucous flow under different spacing and phase differences are observed.

  16. Sequential acid-/alkali-pretreatment of empty palm fruit bunch fiber.

    Science.gov (United States)

    Kim, Seonghun; Park, Jang Min; Seo, Jeong-Woo; Kim, Chul Ho

    2012-04-01

    Pretreatment processes are key technologies for generating fermentable sugars based on lignocellulosic biomass. In this study, we developed a novel method for empty palm fruit bunch fiber (EPFBF) using sequential pretreatment with dilute acid and then alkali. Dilute sulfuric acid was used in the first step, which removed 90% of the hemicellulose and 32% of the lignin, but left most of the cellulose under the optimum pretreatment condition. Sodium hydroxide was then applied in the second step, which extracted lignin effectively with a 70% delignification yield, partially disrupting the ordered fibrils of the EPFBF and thus enhancing the enzyme digestibility of the cellulose. The sequentially pretreated biomass consisted of 82% cellulose, less than 1% hemicellulose, and 30% lignin content afterward. The pretreated biomasses morphologically revealed rough, porous, and irregularly ordered surfaces for enhancing enzyme digestibility. These results indicate that the sequentially acid/alkali-pretreated EPFBF could be broadly useful as a novel biomass.

  17. Multi-Bunch Simulations of the ILC for Luminosity Performance Studies

    CERN Document Server

    White, Glen; Walker, Nicholas J

    2005-01-01

    To study the luminosity performance of the International Linear Collider (ILC) with different design parameters, a simulation was constructed that tracks a multi-bunch representation of the beam from the Damping Ring extraction through to the Interaction Point. The simulation code PLACET is used to simulate the LINAC, MatMerlin is used to track through the Beam Delivery System and GUINEA-PIG for the beam-beam interaction. Included in the simulation are ground motion and wakefield effects, intra-train fast feedback and luminosity-based feedback systems. To efficiently study multiple parameters/multiple seeds, the simulation is deployed on the Queen Mary High-Throughput computing cluster at Queen Mary, University of London, where 100 simultaneous simulation seeds can be run.

  18. Morphological and spectroscopic analysis of cellulose nanocrystals extracted from oil palm empty fruit bunch fiber

    Energy Technology Data Exchange (ETDEWEB)

    Dasan, Y. K., E-mail: aamir.bhat@petronas.com.my; Bhat, A. H., E-mail: aamir.bhat@petronas.com.my [Department of Fundamental and Applied Sciences, Universiti Teknologi PETRONAS, 31750, Bandar Seri Iskandar, Perak (Malaysia); Faiz, A., E-mail: faizahmad@petronas.com.my [Department of Mechanical Engineering, Universiti Teknologi PETRONAS, 31750, Bandar Seri Iskandar, Perak (Malaysia)

    2015-07-22

    This work evaluates the use of oil palm empty fruit bunch (OPEFB) fiber as a source of cellulose to obtain nanocrystalline cellulose (CNC) by acid hydrolysis reaction. The raw OPEFB fibers were pretreated with aqueous Sodium hydroxide at 80°C followed by bleaching treatment and further hydrolyzed with Sulphuric acid at 45°C with limited range of hydrolysis time and acid concentration. The resulting CNC’s were characterized for spectroscopic, crystallographic and morphological properties using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffractometer (XRD), Transmission Electron Microscope (TEM) and Atomic Force Microscopy (AFM). Finding of this study shows that the properties of CNC’s are strongly dependent on the hydrolysis time and acid concentration.

  19. 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.

  20. MD1228: Validation of Single Bunch Stability Threshold & MD1751: Instability Studies with a Single Beam

    CERN Document Server

    Carver, Lee Robert; Biancacci, Nicolo; Buffat, Xavier; Iadarola, Giovanni; Lasocha, Kacper; Li, Kevin Shing Bruce; Levens, Tom; Metral, Elias; Salvant, Benoit; Tambasco, Claudia; CERN. Geneva. ATS Department

    2017-01-01

    Instabilities were being routinely observed in B1V during ADJUST. The timing of the instabilities has been localised to shortly after the TOTEM bump has been implemented. The result is emittance blowup which can negatively effect the luminosity output of the fill. This MD aimed to rule out possible sources of the instability (i.e. beam-beam effects or electron cloud) by only taking one single beam to 6.5TeV and going through the full machine cycle. After the implementation of the TOTEM bump, a reduction of the octupole current was performed in order to determine if there was a discrepancy in the threshold between simulations and measurement. As a precursor, the results of the End of Fill MD: Validation of Single Bunch Stability Threshold will also be described.

  1. Cellulose acetate from oil palm empty fruit bunch via a one step heterogeneous acetylation.

    Science.gov (United States)

    Wan Daud, Wan Rosli; Djuned, Fauzi Muhammad

    2015-11-05

    Acetone soluble oil palm empty fruit bunch cellulose acetate (OPEFB-CA) of DS 2.52 has been successfully synthesized in a one-step heterogeneous acetylation of OPEFB cellulose without necessitating the hydrolysis stage. This has only been made possible by the mathematical modeling of the acetylation process by manipulating the variables of reaction time and acetic anhydride/cellulose ratio (RR). The obtained model was verified by experimental data with an error of less than 2.5%. NMR analysis showed that the distribution of the acetyl moiety among the three OH groups of cellulose indicates a preference at the C6 position, followed by C3 and C2. XRD revealed that OPEFB-CA is highly amorphous with a degree of crystallinity estimated to be ca. 6.41% as determined from DSC. The OPEFB-CA films exhibited good mechanical properties being their tensile strength and Young's modulus higher than those of the commercial CA.

  2. Longitudinal stability of Flat Bunches with Space-Charge or Inductive Impedance

    CERN Document Server

    Santiago Gonzalez, I

    2008-01-01

    We study the loss of Landau damping for the longitudinal plane via the "Sacherer formalism". Stability limits are calculated for several longitudinal beam distributions, in particular for two types of flat bunches, which could be of interest to the LHC upgrade. The resulting stability diagrams are computed and displayed for different azimuthal modes. A general recipe is given for calculating the threshold intensity in the case of a capacitive impedance below transition or, equivalently, for a purely inductive impedance above transition. The formalism was applied to the case of the PS Booster, as an example of space-charge impedance below transition, and to the SPS, as an example of inductive impedance above transition.

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

    CERN Document Server

    Valdivia Garcia, Marco Alan

    2016-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Azhari Samsu Baharuddin,

    2012-06-01

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

  5. Suppression of multiple ion bunches and generation of monoenergetic ion beams in laser foil-plasma

    Institute of Scientific and Technical Information of China (English)

    Zhang Shan; Xie Bai-Song; Hong Xue-Ren; Wu Hai-Cheng; Aimierding Aimidula; Zhao Xue-Yan; Liu Ming-Ping

    2011-01-01

    In one-dimensional particle-in-cell simulations, this paper shows that the formation of multiple ion bunches is disadvantageous to the generation of monoenergetic ion beams and can be suppressed by choosing an optimum target thickness in the radiation pressure acceleration mechanism by a circularly polarised laser pulse. As the laser pulse becomes intense, the optimum target thickness obtained by a non-relativistic treatment is no longer adequate. Considering the relativistic Doppler-shifted pressure, it proposes a relativistic formulation to determine the optimum target thickness. The theoretical predictions agree with the simulation results well. The model is also valid for two-dimensional cases. The accelerated ion beams can be compelled to be more stable by choosing the optimum target thickness when they exhibit some unstable behaviours.

  6. Late-time Structure of the Bunch-Davies FRW Wavefunction

    CERN Document Server

    Konstantinidis, George; Shaghoulian, Edgar

    2016-01-01

    In this short note we organize a perturbation theory for the Bunch-Davies wavefunction in flat, accelerating cosmologies. The calculational technique avoids the in-in formalism and instead uses an analytic continuation from Euclidean signature. We will consider both massless and conformally coupled self-interacting scalars. These calculations explicitly illustrate two facts. The first is that IR divergences get sharper as the acceleration slows. The second is that UV-divergent contact terms in the Euclidean computation can contribute to the absolute value of the wavefunction in Lorentzian signature. Here UV divergent refers to terms involving inverse powers of the radial cutoff in the Euclidean computation. In Lorentzian signature such terms encode physical time dependence of the wavefunction.

  7. SPARC Working Point Optimization for a Bunch with Gaussian Temporal Profile

    CERN Document Server

    Boscolo, Manuela; Fusco, Valeria; Migliorati, Mauro; Reiche, Sven; Ronsivalle, Concetta

    2005-01-01

    We present the optimization of the working point for the SPARC photoinjector with a Gaussian temporal profile. The implications of a Gaussian temporal profile are discussed here for the standard working conditions and for the RF compressor case in comparison with the nominal working point performances of a 10ps flat top pulse with rise time of 1ps. Comparisons with the upgraded version of the HOMDYN code including arbitrary bunch temporal profiles are also reported. Advantages and drawbacks of the Gaussian and flat top pulse shapes are discussed. For the standard working point, it is shown that the two cases provide the same saturation length and average power, but the higher current in the beam core of the Gaussian pulse gives a higher peak radiation power. As the laser pulse shape could be Gaussian at the first stage of the SPARC operation, it is clear the importance of these simulation results.

  8. Enzyme feeding strategies for better fed-batch enzymatic hydrolysis of empty fruit bunch.

    Science.gov (United States)

    Sugiharto, Yohanes Eko Chandra; Harimawan, Ardiyan; Kresnowati, Made Tri Ari Penia; Purwadi, Ronny; Mariyana, Rina; Andry; Fitriana, Hana Nur; Hosen, Hauna Fathmadinda

    2016-05-01

    Lignin inhibitory becomes a major obstacle for enzymatic hydrolysis of empty fruit bunch conducted in high solid loading. Since current technology required high enzyme loading, surfactant application could not effectively used since it is only efficient in low enzyme loading. In addition, it will increase final operation cost. Hence, another method namely "proportional enzyme feeding" was investigated in this paper. In this method, enzyme was added to reactor proportionally to substrate addition, different from conventional method ("whole enzyme feeding") where whole enzyme was added prior to hydrolysis process started. Proportional enzyme feeding could increase enzymatic digestibility and glucose concentration up to 26% and 12% respectively, compared to whole enzyme feeding for hydrolysis duration more than 40h. If enzymatic hydrolysis was run less than 40h (25% solid loading), whole enzyme feeding is preferable.

  9. Pyrolysis of oil palm empty fruit bunch biomass pellets using multimode microwave irradiation.

    Science.gov (United States)

    Salema, Arshad Adam; Ani, Farid Nasir

    2012-12-01

    Oil palm empty fruit bunch pellets were subjected to pyrolysis in a multimode microwave (MW) system (1 kW and 2.45 GHz frequency) with and without the MW absorber, activated carbon. The ratio of biomass to MW absorber not only affected the temperature profiles of the EFB but also pyrolysis products such as bio-oil, char, and gas. The highest bio-oil yield of about 21 wt.% was obtained with 25% MW absorber. The bio-oil consisted of phenolic compounds of about 60-70 area% as detected by GC-MS and confirmed by FT-IR analysis. Ball lightning (plasma arc) occurred due to residual palm oil in the EFB biomass without using an MW absorber. The bio-char can be utilized as potential alternative fuel because of its heating value (25 MJ/kg).

  10. Morphological and spectroscopic analysis of cellulose nanocrystals extracted from oil palm empty fruit bunch fiber

    Science.gov (United States)

    Dasan, Y. K.; Bhat, A. H.; Faiz, A.

    2015-07-01

    This work evaluates the use of oil palm empty fruit bunch (OPEFB) fiber as a source of cellulose to obtain nanocrystalline cellulose (CNC) by acid hydrolysis reaction. The raw OPEFB fibers were pretreated with aqueous Sodium hydroxide at 80°C followed by bleaching treatment and further hydrolyzed with Sulphuric acid at 45°C with limited range of hydrolysis time and acid concentration. The resulting CNC's were characterized for spectroscopic, crystallographic and morphological properties using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffractometer (XRD), Transmission Electron Microscope (TEM) and Atomic Force Microscopy (AFM). Finding of this study shows that the properties of CNC's are strongly dependent on the hydrolysis time and acid concentration.

  11. Electron beam processing of oil palm empty fruit bunch fibers - polypropylene composites

    Energy Technology Data Exchange (ETDEWEB)

    Khairul Zaman, Hj. Mohd Dahlan [Malaysian Institute for Nuclear Technology Research, Kajang, Selangor (Malaysia); Manarpaac, Gloria A.; Jalaluddin, Harun [Universiti Putra Malaysia, Faculty of Forestry, Selangor (Malaysia)

    2002-03-01

    Researches on oil palm empty fruit bunch (EFB) fibers and thermoplastic composites have been carried out by many workers in the last decade. The main focus was to enhance the properties of the resultant composites in view of the incompatibility of the two components. Thus, efforts have been made to enhance their properties by using coupling agents, treating the fibers and modifying the matrices. In this study, the effects of electron beam (EB) irradiation and some reactive additives (RAs) on the mechanical properties of EFB-PP (polypropylene) composites were evaluated. Different modes of irradiation were investigated. Mono, di and tri functional of monomers of RAs were used. Irradiating PP alone, compared to irradiating the EFB fibers or irradiating both components, gave optimum properties for EFB-PP composites. Further improvements of the properties of the composites were achieved with the addition of RAs with TMPTA (trimethylol propane triacrylate) giving the optimum results. (author)

  12. Synthesis and Characterization of Cellulose Acetate from TCF Oil Palm Empty Fruit Bunch Pulp

    Directory of Open Access Journals (Sweden)

    Fauzi Muhammad Djuned

    2014-06-01

    Full Text Available Cellulose acetate (CA was successfully synthesized by the acetylation of TCF cellulose pulp from oil palm empty fruit bunches (OPEFB at room temperature, using acetic anhydride as the acetylating agent and acetic acid as the solvent in the presence of sulfuric acid/sodium bisulfate as catalysts. Degree of substitution (DS was controlled by the variables of acetylation time and acetic anhydride to cellulose ratio, under the heterogeneous state. The product (CA obtained was characterized through Fourier transform infrared spectroscopy (FTIR, nuclear magnetic resonance spectroscopy (NMR, differential scanning calorimetry (DSC, X-ray diffraction (XRD, and scanning electron microscopy (SEM. The results indicate that the CA obtained has characteristics similar to commercial CA, and DS is significantly dependent on acetylation time and the acetic anhydride-to-cellulose ratio.

  13. Tensile and characterization properties of regenerated cellulose empty fruit bunch biocomposite films using ionic liquid

    Science.gov (United States)

    Husseinsyah, Salmah; Zailuddin, Nur Liyana Izyan; Li, Chew Li; Mostapha @ Zakaria, Marliza

    2016-07-01

    The regenerated cellulose (RC) empty fruit bunch (EFB) biocomposite films were prepared using ionic liquid. The tensile strength and modulus of elasticity of regenerated cellulose biocomposite films achieved maximum value at 2 wt% of EFB contents while at 3 and 4 wt% of EFB the tensile strength and modulus of elasticity tend to decreased. The elongation at break tends to decreased at 2 wt% of EFB content but increased at 3 and 4 wt% of EFB contents. The crystallinity index reaches maximum at 2 wt% EFB content, followed by declination with further addition of EFB content. The morphology study illustrated that regenerated cellulose biocomposite films at 2 wt% of EFB contents exhibit a smooth surface that suggested the reinforcement was surrounded by the regenerated cellulose matrix, while at 4 wt% EFB content shows a rough morphology.

  14. 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.

  15. Pretreatment of empty palm fruit bunch for production of chemicals via catalytic pyrolysis.

    Science.gov (United States)

    Misson, Mailin; Haron, Roslindawati; Kamaroddin, Mohd Fadhzir Ahmad; Amin, Nor Aishah Saidina

    2009-06-01

    The effect of chemical pretreatments using NaOH, H(2)O(2), and Ca(OH)(2) on Empty Palm Fruit Bunches (EPFB) to degrade EPFB lignin before pyrolysis was investigated. Spectrophotometer analysis proved consecutive addition of NaOH and H(2)O(2) decomposed almost 100% of EPFB lignin compared to 44% for the Ca(OH)(2), H(2)O(2) system while NaOH and Ca(OH)(2) used exclusively could not alter lignin much. Next, the pretreated EPFB was catalytically pyrolyzed. Experimental results indicated the phenolic yields over Al-MCM-41 and HZSM-5 catalysts were 90 wt% and 80 wt%, respectively compared to 67 wt% yield for the untreated sample under the same set of conditions. Meanwhile, the experiments with HY zeolite yielded 70 wt% phenols.

  16. Polyhydroxybutyrate production from oil palm empty fruit bunch using Bacillus megaterium R11.

    Science.gov (United States)

    Zhang, Youhong; Sun, Wandong; Wang, Hengwei; Geng, Anli

    2013-11-01

    Oil palm empty fruit bunch (OPEFB), contains abundant cellulose and hemicelluloses and can be used as a renewable resource for fuel and chemical production. This study, as the first attempt, aims to convert OPEFB derived sugars to polyhydroxybutyrate (PHB). OPEFB collected from a Malaysia palm oil refinery plant was chemically pretreated and enzymatically hydrolyzed by an in-house prepared cellulase cocktail. The PHB producer, Bacillus megaterium R11, was isolated in Singapore and could accumulate PHB up to 51.3% of its cell dry weight (CDW) from both glucose and xylose. Tryptone was identified as its best nitrogen source. PHB content and production reached 58.5% and 9.32 g/L, respectively, for an overall OPEFB sugar concentration of 45 g/L. These respectively reached 51.6% and 12.48 g/L for OPEFB hydrolysate containing 60 g/L sugar with a productivity of 0.260 g/L/h.

  17. 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.

  18. Purification of empty fruit bunch (EFB) and kenaf soda lignin with acidified water

    Science.gov (United States)

    Hashim, Sharifah Nurul Ain Syed; Zakaria, Sarani; Jaafar, Sharifah Nabihah Syed; Hua, Chia Chin

    2014-09-01

    In this current study, the soda lignins from empty fruit bunch (EFB) and kenaf core were recovered by two step precipitation method. The objective of this research is to study the purity of lignin by washing the lignins with acidified water. The purified lignins were undergone characterization by FT-IR, Uv-Vis and XRD. The FT-IR analysis shows that kenaf core has Guaiacyl(G) and Syringyl(S) unit meanwhile EFB has Hydroxyphenyl(H), Guaiacyl(G) and Syringyl(S) unit of lignin. As for XRD analysis, the non-purified shows that the existence of impurities which is salt (NaCl). The UV analysis shows the higher absorbance which lead to the purity of lignin.

  19. Optimization of lignin production from empty fruit bunch via liquefaction with ionic liquid.

    Science.gov (United States)

    Sidik, Dilaeleyana Abu Bakar; Ngadi, Norzita; Amin, Nor Aishah Saidina

    2013-05-01

    The production of lignin from empty fruit bunch (EFB) has been carried out using liquefaction method with 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) ionic liquid (IL), in presence of sulfuric acid (H2SO4) as a catalyst. Response surface methodology (RSM) based on a factorial Central Composite Design (CCD) was employed to identify the optimum condition for lignin yield. The result indicated that the second order model was adequate for all the independent variables on the response with R(2)=0.8609. The optimum temperature, time, ionic liquid to EFB ratio, and catalyst concentration were 150.5 °C, 151 min, 3:1 wt/wt and 4.73 wt%, respectively for lignin yield=26.6%. The presence of lignin liquefied product was confirmed by UV-Vis and FTIR analysis. It was also demonstrated lignin extraction from lignocellulosic using recycled IL gave sufficient performance.

  20. Characterization of Empty Fruit Bunch Treated with Ionic Liquid Prior to Enzymatic Delignification

    Directory of Open Access Journals (Sweden)

    Revie Financie

    2015-12-01

    Full Text Available The technological utility of enzymes for delignification can be increased by using ionic liquid to open more accessible surface area for biomass transformation into bio-based products. The present paper demonstrates application of ionic liquid (IL [emim][DEP] 1-ethyl-3 methyllimidazolium-diethyl phospate for empty fruit bunch (EFB pretreatment process followed by enzymatic delignification by using Laccase.  It was found that [emim][DEP] increased the performance of the enzyme laccase and henced higher cellulose rich materials, whereas also reduced the lignin content in the EFB. The lowest lignin content obtained from IL-laccase treated EFB was approximately 17.92%, lower than the lignin content in the untreated EFB. Both treated and untreated EFB were characterized in chemical and physical properties by using scanning electron microscope (SEM, fourier transform infrared (FTIR, and thermogravimetric analysis (TGA/DTG to observe the changes resulted from the pretreatment.

  1. 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.

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

    Directory of Open Access Journals (Sweden)

    K. Y. Tshai

    2014-01-01

    Full Text Available 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 ratio of EFB to GLS fibre was varied between Vf of 0 : 20 to 20 : 0. The inclusion of GLS fibres improved the tensile and flexural performance of the hybrid composites, but increasing the glass fibre length from 3 to 6 mm has a negative effect on the mechanical properties of the hybrid composites. Moreover, the composites that were prepared using chloroform showed superior tensile and flexural properties compared to those prepared with dichloromethane.

  3. Sorption of Pb(ll) by poly(hydroxamic acid) grafted oil palm empty fruit bunch.

    Science.gov (United States)

    Haron, M J; Tiansin, M; Ibrahim, N A; Kassim, A; Wan Yunus, W M Z; Talebi, S M

    2011-01-01

    This paper describes the sorption of Pb(ll) from aqueous solution. Oil palm empty fruit bunch (OPEFB) fiber was first grafted with poly(methylacrylate) and then treated with hydroxylammonium chloride in alkaline medium to produce hydroxamic acid (PHA) grafted OPEFB. Sorption of Pb(ll) by PHA-OPEFB was maximum at pH 5. The sorption followed the Langmuir model with maximum capacityof 125.0 mg g-1 at 25 degrees C. The sorption process was exothermic, as shown by the negative value of enthalpy change, Delta H0. The free energy change (DeltaG0) for the sorption was negative, showing that the sorption process was spontaneous. A kinetic study showed that the Pb(ll) sorption followed a second order kinetic model.

  4. Evolution of flavonoids in Mouratón berries taken from both bunch halves.

    Science.gov (United States)

    Figueiredo-González, M; Cancho-Grande, B; Boso, S; Santiago, J L; Martínez, M C; Simal-Gándara, J

    2013-06-01

    Galicia (N.W. Spain) is a Spanish region with several old-traditional winegrowing areas. There are autochthonous grapevine varieties, such as Vitis vinifera L. cv. Mouratón, considered a biodiversity resource in viticulture and an opportunity for Galician sustainable wine production. Therefore, it is necessary to assess the potential of traditional cultivars to produce quality red wines. In this work, anthocyanin and flavonol evolution was followed in red berries from V. vinifera L. cv. Mouratón. The novelty of this study is that grapes were separately collected from two different positions (tips and shoulders) within the cluster, over ripening to examine the effects of berry position within the fruit cluster on the flavonoid compounds. Derivatives of five anthocyanins (malvidin, peonidin, petunidin, delphinidin and cyanidin) and derivatives of six flavonols (quercetin, myricetin, kaempherol, laricitrin isorhamnetin and syringetin) were detected in both positions within the cluster. Dynamic of anthocyanins (from 819 mg/kg to 1206 mg/kg in tips; and from 786 mg/kg to 1077 mg/kg in shoulders) and dynamic of flavonols (from 25mg/kg to 41 mg/kg in tips; and from 18 mg/kg to 21 mg/kg in shoulders) confirmed their upward trends over ripening. Grapes located inside the shoulder bunch receive less sunlight radiation than those located inside the tip bunch and this fact could explain the different accumulation observed for both positions. These results can be useful for winemakers in order to obtain different final red wine quality.

  5. Ontogenesis and nutritive value of warm-season perennial bunch grasses

    Directory of Open Access Journals (Sweden)

    Robert D. Ziehr

    2014-06-01

    Full Text Available Understanding the dynamics of nutritive values in warm-season perennial bunch grasses with change in ontogenesis is essential to managing their use as forage for livestock or cellulosic bioenergy feedstock. Accumulated growth (not previously harvested of Alamo lowland and accession 9065018 upland switch grass (Panicum virgatum, Lometa Indian grass (Sorghastrum nutans, Earl big bluestem (Andropogon gerardii, San Marcos eastern gama grass (Tripsacum dactyloides and Haskell sideoats grama (Bouteloua curtipendula , all native to the southern Great Plains of North America, as well as Selection 75 Klein grass (Panicum coloratum, originating in southern Africa but selected in North America, was harvested every 28 d for 3 yr, commencing 1 yr after establishment. Growth stage, crude protein (CP and in vitro dry matter disappearance (IVDMD over 48 h were evaluated at each date. Some entries, such as Haskell, San Marcos and Selection 75, initiated reproductive growth earlier in the growing season and had higher nutritive value [up to 119 g CP/kg dry matter (DM and 630 g IVDMD/kg DM] at seed set than those reproducing later in the season. Nutritive value of San Marcos and Selection 75 responded to autumn rainfall with resurging nutritive value (over 100 g CP/kg DM and over 600 g IVDMD/kg DM, whereas others did not. These nuances in nutritive value may be useful in manipulating species composition and season of utilization for grazing bunch grasses, especially when incorporated into opportunistic harvests of bioenergy feedstock. Normal 0 false false false EN-US X-NONE X-NONE

  6. Fundamental cavity impedance and longitudinal coupled-bunch instabilities at the High Luminosity Large Hadron Collider

    Science.gov (United States)

    Baudrenghien, P.; Mastoridis, T.

    2017-01-01

    The interaction between beam dynamics and the radio frequency (rf) station in circular colliders is complex and can lead to longitudinal coupled-bunch instabilities at high beam currents. The excitation of the cavity higher order modes is traditionally damped using passive devices. But the wakefield developed at the cavity fundamental frequency falls in the frequency range of the rf power system and can, in theory, be compensated by modulating the generator drive. Such a regulation is the responsibility of the low-level rf (llrf) system that measures the cavity field (or beam current) and generates the rf power drive. The Large Hadron Collider (LHC) rf was designed for the nominal LHC parameter of 0.55 A DC beam current. At 7 TeV the synchrotron radiation damping time is 13 hours. Damping of the instability growth rates due to the cavity fundamental (400.789 MHz) can only come from the synchrotron tune spread (Landau damping) and will be very small (time constant in the order of 0.1 s). In this work, the ability of the present llrf compensation to prevent coupled-bunch instabilities with the planned high luminosity LHC (HiLumi LHC) doubling of the beam current to 1.1 A DC is investigated. The paper conclusions are based on the measured performances of the present llrf system. Models of the rf and llrf systems were developed at the LHC start-up. Following comparisons with measurements, the system was parametrized using these models. The parametric model then provides a more realistic estimation of the instability growth rates than an ideal model of the rf blocks. With this modeling approach, the key rf settings can be varied around their set value allowing for a sensitivity analysis (growth rate sensitivity to rf and llrf parameters). Finally, preliminary measurements from the LHC at 0.44 A DC are presented to support the conclusions of this work.

  7. Performance Analysis of a Bunch and Track Identifier Prototype (BTI) for the CMS Barrel Muon Drift Chambers; Estudio de las Prestaciones de un Prototipo de Bunch and Track Identifier (BTI) para las Camaras de Deriva de CMS

    Energy Technology Data Exchange (ETDEWEB)

    Puerta Pelayo, J.

    2001-07-01

    This note contains a short description of the first step in the first level trigger applied to the barrel muon drift chambers of CMS: the Bunch and Track Identifier (BTI). The test beam results obtained with a BTI prototype have been also analysed BTI performance for different incidence angles and in presence of external magnetic field has been tested, as well as BTI capability as trigger device and track reconstructor. (Author) 30 refs.

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

    CERN Document Server

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

    2015-01-01

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

  9. Commissioning of a compact laser-based proton beam line for high intensity bunches around 10Â MeV

    Science.gov (United States)

    Busold, S.; Schumacher, D.; Deppert, O.; Brabetz, C.; Kroll, F.; Blažević, A.; Bagnoud, V.; Roth, M.

    2014-03-01

    We report on the first results of experiments with a new laser-based proton beam line at the GSI accelerator facility in Darmstadt. It delivers high current bunches at proton energies around 9.6 MeV, containing more than 109 particles in less than 10 ns and with tunable energy spread down to 2.7% (ΔE/E0 at FWHM). A target normal sheath acceleration stage serves as a proton source and a pulsed solenoid provides for beam collimation and energy selection. Finally a synchronous radio frequency (rf) field is applied via a rf cavity for energy compression at a synchronous phase of -90 deg. The proton bunch is characterized at the end of the very compact beam line, only 3 m behind the laser matter interaction point, which defines the particle source.

  10. Experimental Observation of Generation of Superradiance Pulses in the Process of Backscattering of Pump Wave on the Intense Electron Bunch

    CERN Document Server

    Ginzburg, N S; Denisov, G G; Rozental, R M; Sergeev, A; Zotova, I V

    2005-01-01

    Recently significant progress was archived in the generation of multimegawatt subnanosecond pulses in millimeter wave band utilizing the cyclotron and Cherenkov mechanisms of superradiance (SR) [1,2]. We study the novel mechanism of SR when the powerful pumping wave undergoes the stimulated back scattering on the intense electron bunch. Due to the Doppler up shift the radiation frequency can significantly exceed the frequency of the pumping wave. With the relativistic microwave generator as a pumping wave source such a mechanism can be used for generation of the powerful pulse radiation in the short millimeter and submillimeter wave bands. Experiments on the observation of the stimulated scattering in the superradiance regime were carried out at Institute of Electrophysics RAS with two synchronized accelerators. The 4 ns electron beam from the first accelerator is used for generation of the 38 GHz 100 MW pumping wave which subsequently scattered on the subnanosecond 250 keV 1 kA electron bunch produced by the...

  11. Rectangular bunched rutile TiO2 nanorod arrays grown on carbon fiber for dye-sensitized solar cells.

    Science.gov (United States)

    Guo, Wenxi; Xu, Chen; Wang, Xue; Wang, Sihong; Pan, Caofeng; Lin, Changjian; Wang, Zhong Lin

    2012-03-07

    Because of their special application in photovoltaics, the growth of one-dimensional single-crystalline TiO(2) nanostructures on a flexible substrate is receiving intensive attention. Here we present a study of rectangular bunched TiO(2) nanorod (NR) arrays grown on carbon fibers (CFs) from titanium by a "dissolve and grow" method. After a corrosion process in a strong acid solution, every single nanorod is etched into a number of small nanowires. Tube-shaped dye-sensitized solar cells are fabricated by using etched TiO(2) NRs-coated CFs as the photoanode. An absolute energy conversion efficiency of 1.28% has been demonstrated under 100 mW cm(-2) AM 1.5 illumination. This work demonstrates an innovative method for growing bunched TiO(2) NRs on flexible substrates that can be applied in flexible devices for energy harvesting and storage.

  12. Generating quasi-single-cycle THz pulse from frequency-chirped electron bunch train and a tapered undulator

    Institute of Scientific and Technical Information of China (English)

    Zhuoran Ma; Zhe Wang; Feichao Fu; Rui Wang; Dao Xiang

    2016-01-01

    We propose a proof-of-principle experiment to test a new scheme to produce a single-cycle radiation pulse in free-electron lasers(FELs). Here, a few α-BBO crystals will be first used to produce an equally spaced laser pulse train.Then, the laser pulse train illuminates the cathode to produce a frequency-chirped electron bunch train in a photocathode rf gun. Finally, the frequency-chirped electron bunch train passes through a tapered undulator to produce a quasi-single-cycle THz pulse. This experiment should allow comparison and confirmation of predictive models and scaling laws, and the preliminary experimental results will also be discussed.

  13. Bunch motion in the presence of the self-induced voltage due to a reactive impedance with RF off

    Energy Technology Data Exchange (ETDEWEB)

    Shaposhnikova, E. [European Organization for Nuclear Research, Geneva (Switzerland)

    1996-08-01

    Analytic self-consistent solutions have been found for the nonlinear Vlasov equation describing different types of behaviour with time of an intense bunch under the influence of voltage induced due to a reactive part of broad band impedance. The problem is solved for the particular type of the initial distribution function in longitudinal phase space which is elliptic and corresponds to parabolic line density. This paper is devoted to the consideration of the effects in the machine with RF off. In this case the induced voltage is changing with time and can significantly affect bunch motion. The same method applied in the case with RF on allows the time dependent effects of potential well distortion to be analysed. Numerical estimations for the CERN SPS show that effect of induced voltage is important for beam manipulations with RF off. Measurements of the change in the rate of debunching with intensity can be used to estimate the value of the reactive impedance. (author)

  14. Acetic acid-assisted hydrothermal fractionation of empty fruit bunches for high hemicellulosic sugar recovery with low byproducts.

    Science.gov (United States)

    Kim, Dong Young; Um, Byung Hwan; Oh, Kyeong Keun

    2015-07-01

    Xylose, mannose, and galactose (xmg) recovery from empty fruit bunches using acetic acid-assisted hydrothermal (AAH) fractionation method was investigated. Acetic acid has been demonstrated to be effective in xmg recovery in comparison with the liquid hot-water (LHW) fractionation. The maximum xmg recovery yield (50.7 %) from the empty fruit bunch (EFB) was obtained using AAH fractionation at optimum conditions (6.9 wt.% acetic acid at 170 °C and for 18 min); whereas, only 16.2 % of xmg recovery was obtained from the LHW fractionation at the same reaction conditions (170 °C and 18 min). Releasing out the glucose from EFB was kept at low level (<1.0 %) through all tested conditions and consequently negligible 5-HMF and formic acid were analyzed in the hydrolyzate. The production of furfural was also resulted with extremely low level (1.0 g/L).

  15. "Meshed-Bag Gathered-Bunch" method for solid-phase synthesis of small molecular diverse compounds.

    Science.gov (United States)

    Zhang, Suo-De; Liu, Gang; Xia, Shu-Quan; Wu, Ping; Zhang, Liang

    2002-01-01

    A new "Meshed-Bag Gathered-Bunch" technology for the solid-phase synthesis of chemical libraries was developed. Using such technology, we synthesized muramyl dipeptide mimetics including derivatives at the N- and C-terminus, cyclic muramyl dipeptide mimetics, muramyl dipeptide and Tuftsin's analogue conjugates. The advantages of such a method include ease of manufacture, low unit cost of production, the physical encoding method, and the compatibility with both parallel and "split-mix" approaches.

  16. Evaluation of phase bunching in the central region of a cyclotron by a radial probe with a plastic scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Miyawaki, Nobumasa, E-mail: miyawaki.nobumasa@jaea.go.jp [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Fukuda, Mitsuhiro [Research Center for Nuclear Physics, Osaka University, 10-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Kurashima, Satoshi; Kashiwagi, Hirotsugu; Okumura, Susumu [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan); Arakawa, Kazuo [Gunma University Heavy Ion Medical Center, Gunma University, 3-39-22 Showa-Machi, Maebashi, Gunma, 371-8511 (Japan); Kamiya, Tomihiro [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, Gunma 370-1292 (Japan)

    2014-12-11

    A new technique for evaluating the phase bunching performance in the central region of a cyclotron was developed. A newly-developed radial probe with a 6-mm-wide, 5-mm-height plastic scintillator was applied to analysis of the correlation between the internal beam phase distribution and the initial beam phase, defined by adjusting the relative RF phase of the beam buncher. The phase distribution measurement system, comprising the radial probe equipped with a plastic scintillator and the signal-processing modules, had a sufficiently good time resolution of 45 ps full-width at half-maximum for the phase bunching evaluation. The correlations between the buncher phase and the measured phase distribution for the acceleration harmonic number h=1 and 2 were consistent with the calculation result of the geometric trajectory analysis. For h=1 case of a 107 MeV {sup 4}He{sup 2+} beam, the internal beam phase region spread over 71 RF degrees full-width at quarter-maximum (FWQM) for the acceptable buncher phase region of 48 RF degrees, and no evidence of the phase bunching effect was observed. For h=2 case of a 260 MeV {sup 20}Ne{sup 7+} beam, the internal beam phase region for the acceptable buncher phase region of 59 RF degrees was compressed into 21 RF degrees FWQM. The phase bunching effect was sharply evident for h=2, and contributed to increase of the acceptable beam phase region and the beam intensity per phase width.

  17. Peak power tunable mid-infrared oscillator pumped by a high power picosecond pulsed fiber amplifier with bunch output

    Science.gov (United States)

    Wei, Kaihua; Guo, Yan; Lai, Xiaomin; Fan, Shanhui

    2016-07-01

    A high power mid-infrared optical parametric oscillator (OPO) with picosecond pulse bunch output is experimentally demonstrated. The pump source was a high power master oscillation power amplifier (MOPA) picosecond pulsed fiber amplifier. The seed of the MOPA was a gain-switched distributed Bragg reflector (DBR) laser diode (LD) with picosecond pulse operation at a high repetition rate. The seed laser was amplified to 50 W by two-stage pre-amplifiers and a large mode area (LMA) Yb fiber based power-amplifier. A fiber-pigtailed acousto-optic modulator with the first order diffraction transmission was inserted into the second pre-amplifier to form a picosecond pulse bunch train and to change the peak power simultaneously. The power-amplified pulse bunches were focused to pump a wavelength-tunable OPO for emitting high power mid-infrared laser. By adjusting the OPO cavity length, the maximum average idler powers obtained at 3.1, 3.3 and 3.5 μm were 7, 6.6 and 6.4 W respectively.

  18. Effect of bunch sanitation on spatial distributions of abscised fruit and phycitine moths (Lepidoptera: Pyralidae) in California date gardens.

    Science.gov (United States)

    Nay, Justin E; Park, Yong-Lak; Perring, Thomas M

    2007-12-01

    Phycitine moths are an economic impediment to California date, Phoenix dactylifera L., production. Summer populations build to damaging levels on abscised dates that get trapped in fruit bunches. This study was conducted to determine the relationship between abscised fruit and moth infestation, and to evaluate changes in the spatial distribution of abscised fruit and moth-infested fruit after a bunch-sanitation treatment. Over the 9 wk of this study, there was a 69.9% reduction in the number of moth-infested fruit after a single sanitation treatment. Linear regression analysis showed a significant relationship between abscised fruit and phycitine moth-infested fruit; 42 and 76.6% of the variation in the number of infested fruit was explained by the number of abscised fruit in noncleaned and cleaned plots, respectively. The pattern of reinfestation by moths over the 9 wk posttreatment period was analyzed with spatial analysis with distance indices. Significant spatial associations were found between abscised fruit and moth-infested fruit, supporting the regression analysis. The sanitation treatments caused significant gaps in both abscised fruit and moth-infested fruit. Over time, gap sizes became smaller, indicating a nonrandom pattern of reinfestation that likely was caused by the movement of moths from nontreated areas into treated areas. This study, the first spatial analysis conducted in dates, suggests that in-season bunch sanitation could be effective at reducing summer moth densities if applied on a large regional scale.

  19. A field programmable gate array-based time-resolved scaler for collinear laser spectroscopy with bunched radioactive potassium beams.

    Science.gov (United States)

    Rossi, D M; Minamisono, K; Barquest, B R; Bollen, G; Cooper, K; Davis, M; Hammerton, K; Hughes, M; Mantica, P F; Morrissey, D J; Ringle, R; Rodriguez, J A; Ryder, C A; Schwarz, S; Strum, R; Sumithrarachchi, C; Tarazona, D; Zhao, S

    2014-09-01

    A new data acquisition system including a Field Programmable Gate Array (FPGA) based time-resolved scaler was developed for laser-induced fluorescence and beam bunch coincidence measurements. The FPGA scaler was tested in a collinear laser-spectroscopy experiment on radioactive (37)K at the BEam COoler and LAser spectroscopy (BECOLA) facility at the National Superconducting Cyclotron Laboratory at Michigan State University. A 1.29 μs bunch width from the buncher and a bunch repetition rate of 2.5 Hz led to a background suppression factor of 3.1 × 10(5) in resonant photon detection measurements. The hyperfine structure of (37)K and its isotope shift relative to the stable (39)K were determined using 5 × 10(4) s(-1) (37)K ions injected into the BECOLA beam line. The obtained hyperfine coupling constants A((2)S(1/2)) = 120.3(1.4) MHz, A((2)P(1/2)) = 15.2(1.1) MHz, and A((2)P(3/2)) = 1.4(8) MHz, and the isotope shift δν(39, 37) = -264(3) MHz are consistent with the previously determined values, where available.

  20. A field programmable gate array-based time-resolved scaler for collinear laser spectroscopy with bunched radioactive potassium beams

    Science.gov (United States)

    Rossi, D. M.; Minamisono, K.; Barquest, B. R.; Bollen, G.; Cooper, K.; Davis, M.; Hammerton, K.; Hughes, M.; Mantica, P. F.; Morrissey, D. J.; Ringle, R.; Rodriguez, J. A.; Ryder, C. A.; Schwarz, S.; Strum, R.; Sumithrarachchi, C.; Tarazona, D.; Zhao, S.

    2014-09-01

    A new data acquisition system including a Field Programmable Gate Array (FPGA) based time-resolved scaler was developed for laser-induced fluorescence and beam bunch coincidence measurements. The FPGA scaler was tested in a collinear laser-spectroscopy experiment on radioactive 37K at the BEam COoler and LAser spectroscopy (BECOLA) facility at the National Superconducting Cyclotron Laboratory at Michigan State University. A 1.29 μs bunch width from the buncher and a bunch repetition rate of 2.5 Hz led to a background suppression factor of 3.1 × 105 in resonant photon detection measurements. The hyperfine structure of 37K and its isotope shift relative to the stable 39K were determined using 5 × 104 s-1 37K ions injected into the BECOLA beam line. The obtained hyperfine coupling constants A(2S1/2) = 120.3(1.4) MHz, A(2P1/2) = 15.2(1.1) MHz, and A(2P3/2) = 1.4(8) MHz, and the isotope shift δν39, 37 = -264(3) MHz are consistent with the previously determined values, where available.

  1. Within-Vineyard, Within-Vine, and Within-Bunch Variability of the Rotundone Concentration in Berries of Vitis vinifera L. cv. Shiraz.

    Science.gov (United States)

    Zhang, Pangzhen; Barlow, Snow; Krstic, Mark; Herderich, Markus; Fuentes, Sigfredo; Howell, Kate

    2015-05-06

    This study characterizes the environmental factors driving rotundone concentrations in grape berries by quantifying rotundone variability and correlating it with viticultural parameters. Dissection of the vineyard into distinct zones (on the basis of vigor, electrical soil conductivity, and slope), vine into orientations to sun (shaded/unshaded), and grape bunches into sectors (upper and lower and front and back) shows the influence of vine vigor, sunlight, and temperature. Occurrence of the highest rotundone concentration was observed in shaded bunch sectors and vines and from higher vigor vines in the southern-facing areas of the vineyard. The highest concentration of rotundone is consistently found at the top and in shaded sectors of bunches, and this correlates to lower grape surface temperatures. Modeling showed that berry temperature exceeding 25 °C negatively affects the rotundone concentration in Shiraz. Both natural and artificial shading modulated the grape surface and air temperature at the bunch zone and increased the rotundone concentration, without affecting other grape berry quality parameters. Thus, temperature and possibly sunlight interception are the main determinants of rotundone in grape berries. Vineyard topography, vine vigor, vine row, and grape bunch orientation influence the level of berry shading and can, therefore, adjust bunch surface and zone temperatures and influence the berry rotundone concentration.

  2. Grassland structural heterogeneity in a savanna is driven more by productivity differences than by consumption differences between lawn and bunch grasses.

    Science.gov (United States)

    Veldhuis, Michiel P; Fakkert, Heleen F; Berg, Matty P; Olff, Han

    2016-11-01

    Savanna grasslands are characterized by high spatial heterogeneity in vegetation structure, aboveground biomass and nutritional quality, with high quality short-grass grazing lawns forming mosaics with patches of tall bunch grasses of lower quality. This heterogeneity can arise because of local differences in consumption, because of differences in productivity, or because both processes enforce each other (more production and consumption). However, the relative importance of both processes in maintaining mosaics of lawn and bunch grassland types has not been measured. Also their interplay been not been assessed across landscape gradients. In a South African savanna, we, therefore, measured the seasonal changes in primary production, nutritional quality and herbivore consumption (amount and percentage) of grazing lawns and adjacent bunch grass patches across a rainfall gradient. We found both higher amounts of primary production and, to a smaller extent, consumption for bunch grass patches. In addition, for bunch grasses primary production increased towards higher rainfall while foliar nitrogen concentrations decreased. Foliar nitrogen concentrations of lawn grasses decreased much less with increasing rainfall. Consequently, large herbivores targeted the biomass produced on grazing lawns with on average 75 % of the produced biomass consumed. We conclude that heterogeneity in vegetation structure in this savanna ecosystem is better explained by small-scale differences in productivity between lawn and bunch grass vegetation types than by local differences in consumption rates. Nevertheless, the high nutritional quality of grazing lawns is highly attractive and, therefore, important for the maintenance of the heterogeneity in species composition (i.e. grazing lawn maintenance).

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

    Energy Technology Data Exchange (ETDEWEB)

    Tanjia, F., E-mail: tanjia.fatema@gmail.com [Dipartimento di Fisica, Universià di Napoli “Federico II” (Italy); INFN Sezione di Napoli (Italy); Fedele, R. [Dipartimento di Fisica, Universià di Napoli “Federico II” (Italy); INFN Sezione di Napoli (Italy); De Nicola, S. [Dipartimento di Fisica, Universià di Napoli “Federico II” (Italy); INFN Sezione di Napoli (Italy); CNR-SPIN, Complesso Universitario di Monte S' Angelo, Napoli (Italy); Akhter, T. [Dipartimento di Fisica, Universià di Napoli “Federico II” (Italy); INFN Sezione di Napoli (Italy); Jovanović, D. [Institute of Physics, University of Belgrade, Belgrade (Serbia)

    2016-09-01

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

  4. Nanoporous separators for supercapacitor using activated carbon monolith electrode from oil palm empty fruit bunches

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-02-24

    Activated porous carbon electrode prepared from fibres of oil palm empty fruit bunches was used for preparing the carbon based supercapacitor cells. The symmetrical supercapacitor cells were fabricated using carbon electrodes, stainless steel current collector, H{sub 2}SO{sub 4} electrolyte, and three types of nanoporous separators. Cells A, B and C were fabricated using polypropylene, eggshell membrane, and filter paper, respectively. Electrochemical characterizations data from Electrochemical Impedance Spectroscopy, Cyclic Voltammetry, and Galvanic Charge Discharge techniques showed that specific capacitance, specific power and specific energy for cell A were 122 F g{sup −1}, 177 W kg{sup −1}, 3.42 Wh kg{sup −1}, cell B; 125 F g{sup −1}, 179 W kg{sup −1}, and 3.64 Wh kg{sup −1}, and cell C; 180 F g{sup −1}, 178 W kg{sup −1}, 4.27 Wh kg{sup −1}. All the micrographs from Field Emission Scanning Electron Microscope showed that the different in nanoporous structure of the separators lead to a significant different in influencing the values of specific capacitance, power and energy of supercapacitors, which is associated with the mobility of ion into the pore network. These results indicated that the filter paper was superior than the eggshell membrane and polypropylene nanoporous separators. However, we found that in terms of acidic resistance, polypropylene was the best nanoporous separator for acidic medium.

  5. R & D on Beam Injection and Bunching Schemes in the Fermilab Booster

    Energy Technology Data Exchange (ETDEWEB)

    Bhat, C. M. [Fermilab

    2016-01-01

    Fermilab is committed to upgrade its accelerator complex to support HEP experiments at the intensity frontier. The ongoing Proton Improvement Plan (PIP) enables us to reach 700 kW beam power on the NuMI neutrino targets. By the end of the next decade, the current 400 MeV normal conducting LINAC will be replaced by an 800 MeV superconducting LINAC (PIP-II) with an increased beam power >50% of the PIP design goal. Both in PIP and PIP-II era, the existing Booster is going to play a very significant role, at least for next two decades. In the meanwhile, we have recently developed an innovative beam injection and bunching scheme for the Booster called "early injection scheme" that continues to use the existing 400 MeV LINAC and implemented into operation. This scheme has the potential to increase the Booster beam intensity by >40% from the PIP design goal. Some benefits from the scheme have already been seen. In this paper, I will describe the basic principle of the scheme, results from recent beam experiments, our experience with the new scheme in operation, current status, issues and future plans. This scheme fits well with the current and future intensity upgrade programs at Fermilab.

  6. Acetylation of oil palm empty fruit bunch fiber as an adsorbent for removal of crude oil.

    Science.gov (United States)

    Asadpour, Robabeh; Sapari, Nasiman B; Isa, Mohamed Hasnain; Kakooei, Saeid

    2016-06-01

    Removal of oil spillage from the environment is a global concern. Various methods, including the use of fibers as sorbents, have been developed for oil spill control. Oil palm empty fruit bunch (OPEFB) fiber is a plant biomass that may be acetylated by acetic anhydride using N-bromosuccinimide (NBS) as a catalyst; here, the extent of acetylation may be calculated in terms of weight percent gain (WPG). The modified fiber was used to remove Tapis and Arabian crude oils. The optimum time, temperature, and catalyst concentration were 4 h, 120 °C, and 3 %, respectively, and these parameters could achieve an 11.49 % increase in WPG. The optimized parameters improved the adsorption capacity of OPEFB fibers for crude oil removal. The acetylated OPEFB fibers were characterized by using Fourier transform infrared spectroscopy and field emission scanning electron microscopy to observe the functional groups available and morphology. Kinetic and isotherm studies were conducted using different contact times and oil/water ratios. The rate of oil sorption onto the OPEFB fibers can be adequately described by the pseudo-second-order equation. Adsorption studies revealed that adsorption of crude oil on treated OPEFB fiber could be best described by the Langmuir isotherm model.

  7. Induction Acceleration of a Single RF Bunch in the KEK PS

    CERN Document Server

    Takayama, Ken; Arakida, Yoshio; Horioka, Kazuhiko; Igarashi, Susumu; Iwashita, Taiki; Kawasaki, Atsushi; Kishiro, Junichi; Kono, Tadaaki; Koseki, Kunio; Nakamura, Eiji; Sakuda, Makoto; Sato, Hikaru; Shiho, Makoto; Shimosaki, Yoshito; Shirakata, Masashi; Sueno, Tsuyoshi; Tokuchi, Akira; Torikai, Kota; Toyama, Takeshi; Wake, Masayoshi; Watanabe, Masao; Yamane, Isao

    2005-01-01

    A single bunch trapped in an RF bucket was accelerated by induction devices from 500 MeV to 8GeV beyond transition energy in the KEK-PS. This is the first demonstration of induction acceleration in a high energy circular ring. The acceleration was confirmed by measuring a temporal evolution of the RF phase through an entire acceleration.* Key devices in an induction acceleration system are an induction accelerating cavity capable of generating an induced voltage of 2kV/cell, a pulse modulator to drive the cavity (switching driver), and a DSP system to control gate signals for switching. Their remarkable characteristics are its repetition ratio of about 1MHz and duty factor of 50%. All devices have been newly developed at KEK so as to meet this requirement. The pulse modulator employing MOSFETs as switching elements is connected with the accelerating cavity through a long transmission cable in order to avoid a high-dose irradiation in the accelerator tunnel. The induction system has been running beyond more th...

  8. Strain-induced step bunching in orientation-controlled GaN on Si

    Science.gov (United States)

    Narita, Tetsuo; Iguchi, Hiroko; Horibuchi, Kayo; Otake, Nobuyuki; Hoshi, Shinichi; Tomita, Kazuyoshi

    2016-05-01

    We report a technique for the fabrication of high-quality GaN-on-silicon (Si) substrates for use in various power applications. GaN epitaxial layers were generated on Si(111) vicinal faces that had been previously covered with a thin coating of Al2O3 to control the orientation of the AlN seed layers. We obtained orientation-controlled GaN layers and found a linear relationship between the GaN c-axis and Si[111] tilt angles. As a result, the threading dislocation density in the AlN seed layer was reduced and high-quality GaN layers were generated. The X-ray rocking curves for these layers exhibited full width at half maximum values of 390‧‧ and 550‧‧ for the (004) and (114) reflections, respectively. Significant step bunching was observed on a GaN(0001) vicinal face produced using this technique, attributed to strain-induced attractive interactions between steps. Thus, by controlling the strain near the surface layer, we achieved the step flow growth of GaN on Si.

  9. Energy spread minimization in a cascaded laser wakefield accelerator via velocity bunching

    Science.gov (United States)

    Zhang, Zhijun; Li, Wentao; Liu, Jiansheng; Wang, Wentao; Yu, Changhai; Tian, Ye; Nakajima, Kazuhisa; Deng, Aihua; Qi, Rong; Wang, Cheng; Qin, Zhiyong; Fang, Ming; Liu, Jiaqi; Xia, Changquan; Li, Ruxin; Xu, Zhizhan

    2016-05-01

    We propose a scheme to minimize the energy spread of an electron beam (e-beam) in a cascaded laser wakefield accelerator to the one-thousandth-level by inserting a stage to compress its longitudinal spatial distribution. In this scheme, three-segment plasma stages are designed for electron injection, e-beam length compression, and e-beam acceleration, respectively. The trapped e-beam in the injection stage is transferred to the zero-phase region at the center of one wakefield period in the compression stage where the length of the e-beam can be greatly shortened owing to the velocity bunching. After being seeded into the third stage for acceleration, the e-beam can be accelerated to a much higher energy before its energy chirp is compensated owing to the shortened e-beam length. A one-dimensional theory and two-dimensional particle-in-cell simulations have demonstrated this scheme and an e-beam with 0.2% rms energy spread and low transverse emittance could be generated without loss of charge.

  10. Experimental observation of attosecond control over relativistic electron bunches with two-colour fields

    Science.gov (United States)

    Yeung, M.; Rykovanov, S.; Bierbach, J.; Li, L.; Eckner, E.; Kuschel, S.; Woldegeorgis, A.; Rödel, C.; Sävert, A.; Paulus, G. G.; Coughlan, M.; Dromey, B.; Zepf, M.

    2017-01-01

    Energy coupling during relativistically intense laser-matter interactions is encoded in the attosecond motion of strongly driven electrons at the pre-formed plasma-vacuum boundary. Studying and controlling this motion can reveal details about the microscopic processes that govern a vast array of light-matter interaction phenomena, including those at the forefront of extreme laser-plasma science such as laser-driven ion acceleration, bright attosecond pulse generation and efficient energy coupling for the generation and study of warm dense matter. Here we experimentally demonstrate that by precisely adjusting the relative phase of an additional laser beam operating at the second harmonic of the driving laser it is possible to control the trajectories of relativistic electron bunches formed during the interaction with a solid target at the attosecond scale. We observe significant enhancements in the resulting high-harmonic yield, suggesting potential applications for sources of ultra-bright, extreme ultraviolet attosecond radiation to be used in atomic and molecular pump-probe experiments.

  11. Activated carbons derived from oil palm empty-fruit bunches: Application to environmental problems

    Institute of Scientific and Technical Information of China (English)

    Md.Zahangir ALAM; Suleyman A.MUYIBI; Mariatul F.MANSOR; Radziah WAHID

    2007-01-01

    Activated carbons derived from oil palm empty fruit bunches (EFB) were investigated to find the suitability of its application for removal of phenol in aqueous solution through adsorption process. Two types of activation namely; thermal activation at 300, 500 and 800℃ and physical activation at 150℃ (boiling treatment) were used for the production of the activated carbons. A control (untreated EFB) was used to compare the adsorption capacity of the activated carbons produced from these processes. The results indicated that the activated carbon derived at the temperature of 800℃ showed maximum absorption capacity in the aqueous solution of phenol. Batch adsorption studies showed an equilibrium time of 6 h for the activated carbon at 800℃. It was observed that the adsorption capacity was higher at lower values of pH (2-3) and higher value of initial concentration of phenol (200-300 mg/L). The equilibrium data fitted better with the Freundlich adsorption isotherm compared to the Langmuir. Kinetic studies of phenol adsorption onto activated carbons were also studied to evaluate the adsorption rate. The estimated cost for production of activated carbon from EFB was shown in lower price (USD 0.50/kg of AC) compared the activated carbon from other sources and processes.

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

    Directory of Open Access Journals (Sweden)

    Ana Ferrer

    2011-04-01

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

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

    Directory of Open Access Journals (Sweden)

    N. S. Lani

    2014-01-01

    Full Text Available 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 and their reinforcing effect on polyvinyl alcohol (PVA/starch blend films. A series of PVA/starch films with different content of nanocellulose were prepared by solution casting method. Nanocellulose fiber with diameters ranging from 4 to 15 nm has been successfully prepared. On the other hand, PVA/starch films reinforced with nanocellulose fiber possess significantly improved properties compared to unreinforced film. From the results, PVA/starch films with the addition of 5% (v/v of nanocellulose exhibited best combination of properties. This nanocomposite was found to have tensile strength at about 5.694 MPa and elongation at break was 481.85%. In addition to good mechanical properties, this nanocomposite has good water resistance and biodegradability.

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

    Directory of Open Access Journals (Sweden)

    Yakum Reneta Nafu

    2015-01-01

    Full Text Available 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 infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Fibre yield was higher for spikelet than stalk. Fibres from stalk were generally larger in diameter and showed significant differences in potassium and galacturonic acid content, strength, and rigidity. Scanning electron microscopy confirmed the widespread occurrence of silica bodies as well as significant differences in the microstructure of stalk and spikelet fibres. Stalk fibres showed a greater level of porosity than spikelet fibres in the section perpendicular to the major axis. The morphology of KOH-boric acid treated fibres suggested higher recalcitrance of spikelet fibres. The significant differences between fibres from stalk and spikelet suggest that EFB, used as feedstock for biobased industries, requires more systematic characterization and separation into stalk and spikelet, which may lead to a more judicious exploitation of this valuable waste.

  15. Much Ado about Microbunching: Coherent Bunching in High Brightness Electron Beams

    Energy Technology Data Exchange (ETDEWEB)

    Ratner, Daniel [Stanford Univ., CA (United States)

    2011-05-01

    The push to provide ever brighter coherent radiation sources has led to the creation of correspondingly bright electron beams. With billions of electrons packed into normalized emittances (phase space) below one micron, collective effects may dominate both the preservation and use of such ultra-bright beams. An important class of collective effects is due to density modulations within the bunch, or microbunching. Microbunching may be deleterious, as in the case of the Microbunching Instability (MBI), or it may drive radiation sources of unprecedented intensity, as in the case of Free Electron Lasers (FELs). In this work we begin by describing models of microbunching due to inherent beam shot noise, which sparks both the MBI as well as SLAC's Linac Coherent Light Source, the world's first hard X-ray laser. We first use this model to propose a mechanism for reducing the inherent beam shot noise as well as for predicting MBI effects. We then describe experimental measurements of the resulting microbunching at LCLS, including optical radiation from the MBI, as well as the first gain length and harmonic measurements from a hard X-ray FEL. In the final chapters, we describe schemes that use external laser modulations to microbunch light sources of the future. In these sections we describe coherent light source schemes for both both linacs and storage rings.

  16. Positron Bunch Radiation in the System of Tightly-Packed Nanotubes

    CERN Document Server

    Gevorgyan, Koryun; Gevorgyan, Hayk

    2015-01-01

    The problem of channeling radiation of positron bunch in the system of packed nanotubes was investigated in the present work. Used the model of harmonic potential which is justified since on the one hand the number of positrons in the region near the axis of nanotube is small, and on the other hand their contribution to the formation of the total radiation is also small. The problem is solved in the dipole approximation. The radiation at first harmonic occurs at zero angle too. At zero angle are radiated both extremely hard and extremely soft photons due to the medium polarization. The frequency-angular distribution of number of emitted photons was received. The distribution does not depend on the azimuthal angle, since the task has cylindrical symmetry. Radiation at the zero angle is fully circularly polarized. For formation of radiation there is an energy threshold: lower threshold is due to the polarization of medium, the upper threshold depends on the oscillation amplitude of channelling positrons. When t...

  17. 3D simulations on output power fluctuation in a short bunch rf-linac FEL

    Science.gov (United States)

    Sentoku, Y.; Furukawa, H.; Mima, K.; Taguchi, T.; Kuruma, S.; Yasuda, H.; Yamanaka, C.; Nakai, S.

    1995-04-01

    A space-time dependent 3D simulation code has been developed in order to analyze the RF-linac FEL oscillator dynamics. Our simulation code employed both the transverse mode spectral method and the longitudinal finite difference method. The electron beam is modeled by a group of super particles which have a density profile in the time domain. In this model the electron beam is able to determine the energy spread and the finite emittance. This simulation code enables us to describe the transverse mode competition and the slippage effects in the resonator cavity. In this paper, a high power infrared FEL with a short bunch electron beam is investigated. The output power fluctuation with cavity desynchronism is simulated with this code. Especially, we investigated the effects of the transverse mode competition, energy spread, and the finite emittance of the electron beam on the output fluctuation. Using FELIX parameters, the FEL oscillator is simulated for 300 passes. The output power oscillates periodically in the case of single transverse mode and not in the case of multi-transverse modes. In a warm beam with multi-transverse modes, the emission is higher than that with a single mode, and the optical pulse shape is almost the after 100 passes. Furthermore, the phase space motion of the laser field is periodic and stable. As a result of the simulation, we recommend that high power infrared FEL operation should include multi-transverse modes in order to get higher emission and a more stable optical pulse.

  18. Design study of a re-bunching RFQ for the SPES project

    Science.gov (United States)

    Shin, Seung Wook; Palmieri, A.; Comunian, M.; Grespan, F.; Chai, Jong Seo

    2014-05-01

    An upgrade to the 2nd generation of the selective production of exotic species (SPES) to produce a radioactive ion beam (RIB) has been studied at the istituto nazionale di fisica nucleare — laboratory nazionali di Legnaro (INFN-LNL). Due to the long distance between the isotope separator online (ISOL) facility and the superconducting quarter wave resonator (QWR) cavity acceleratore lineare per ioni (ALPI), a new re-buncher cavity must be introduced to maintain the high beam quality during the beam transport. A particular radio frequency quadrupole (RFQ) structure has been suggested to meet the requirements of this project. A window-type RFQ, which has a high mode separation, less power dissipation and compact size compared to the conventional normal 4-vane RFQ, has been introduced. The RF design has been studied considering the requirements of the re-bunching machine for high figures of merit such as a proper operation frequency, a high shunt impedance, a high quality factor, a low power dissipation, etc. A sensitivity analysis of the fabrication and the misalignment error has been conducted. A micro-movement slug tuner has been introduced to compensate for the frequency variations that may occur due to the beam loading, the thermal instability, the microphonic effect, etc.

  19. Preparation and Characterization of Cellulose Microcrystalline (MCC) from Fiber of Empty Fruit Bunch Palm Oil

    Science.gov (United States)

    Nasution, H.; Yurnaliza; Veronicha; Irmadani; Sitompul, S.

    2017-03-01

    Alpha cellulose which was isolated from cellulose of fiber empty fruit bunch palm oil was hidrolized with hydrochloric acid (2,5N) at 80°C to produce microcrystalline cellulose (MCC). Microcrystalline cellulose is an important additional ingredient in the pharmaceutical, food, cosmetics, and structural composites. In this study, MCC, alpha cellulose, and cellulose were characterized and thereafter were compared. Characterizations were made using some equipment such as x-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and thermogravimetry analyzer (TGA). X-ray diffraction and infrared spectroscopy were studied to determine crystallinity and molecular structure of MCC, where scanning electron microscopy images were conducted for information about morfology of MCC. Meanwhile, thermal resistance of MCC was determined using thermogravimetry analyzer (TGA). From XRD and FTIR, the obtained results showed that the crystalline part was traced on MCC, where the –OH and C-O groups tended to reduced as alpha cellulose has changed to MCC. From SEM the image showed the reduction of particle size of MCC, while the thermal resistance of MCC was found lower as compared with cellulose and alpha cellulose as well, which was attributed to the lower molecular weight of MCC.

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

    Directory of Open Access Journals (Sweden)

    Nassereldeen Ahmed Kabbashi

    2010-09-01

    Full Text Available 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 optimization. The optimization of process conditions, by using central composite design (CCD was carried out. Optimization of process condition was done with varied level of moisture content, pH, inoculum size, concentration of co-substrate (wheat flour and mineral solutions. Statistical analysis showed that the optimum process condition for moisture content was 50% (v/w, pH of 4, inoculum size of 10% (v/v, concentration of wheat flour of 1% (v/v and mineral solutions 1%(v/v. In this study, the application levels of the methods of environmental management in regards to the maximum production were determined. The final optimization with the developed process conditions indicated that the maximum production was increased from 14.315 (v/v to 34.785(v/v.