Recently, producing and maintaining short bunches in accelerators has become a forefront issue. Examples of accelerators that require short bunches are high quality nuclear physics accelerators, free electron laser driver accelerators, next generation ...

This paper discusses a novel idea to accelerate low-intensity bunches of electrons (or positrons) by the wake field of intense proton bunches travelling along the axis of a cylindrical rf structure. Accelerating gradients in excess of 100 MeV/m and large ...

Laser-driven plasma-based accelerators are capable of producing ultrashort electron bunches in which the longitudinal size is much smaller than the transverse size. We present theoretical studies of the transport of such electron bunches in vacuum. Space charge forces acting on the ...

Electron beam bunching in the optical wavelength was observed experimentally for the first time at the Brookhaven Accelerator Test Facility (ATF) using the Inverse Free Electron (IFEL) accelerator. The micro-bunched electron beam has been studied by ...

Several theories have been proposed to explain anomalous bunch lengthening and widening in particle storage rings. All these theories either assume a modification of the accelerating potential well or a high frequency self-bunching mechanism similar to th...

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 ...

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 ...

... of an X-band linear accelerator for production of a beam having high ... A small angle theory of bunching in a distributed buncher is developed and ...

The electric field carried along by a SLC bunch is very intense at the surface of the bunch because of the bunch's tiny transverse dimensions and its high charge density. For a given bunch population, the maximum electric field - which occurs at the surface - is inversely proportional to the ...

The compression and acceleration of an external electron bunch into the laser wakefield is studied using 3D modeling with the LAPLAC code and compared to analytical predictions. It is shown, for a laser propagating in a plasma channel, that the nonlinear laser pulse dynamics together with the finite laser spot size influence the ...

Coherent transition radiation is used to measure the length of the ultra-short electron bunches available at the Stanford Linear Accelerator Center. The results and the limitations of the method are described.

The Argonne Wakefield Accelerator group develops accelerating structures based on dielectric loaded waveguides. We use high charge short electron bunches to excite wakefields in dielectric loaded structures, and a second (low charge) beam to probe the wak...

Laser-driven plasma-based accelerators are capable of producing ultrashort electron bunches in which the longitudinal size is much smaller than the transverse size. We present theoretical studies of the transport of such electron bunches in vacuum. Space ...

As was discussed earlier [1,2] longitudinal space charge force in initially nonuniform bunch transforms density fluctuations into energy modulation along the bunch. For characterization of the resulted energy modulation one can chirp the bunch using accelerator section, located upstream of beam spectrometer, and ...

At Stanford Linear Accelerator Center (SLAC) a Bunch Length Measurement system has been developed to measure the length of the electron bunch for its new Linac Coherent Light Source (LCLS). This destructive measurement uses a transverse-mounted RF deflect...

ated with a relativistic electron-positron jet front propagating into an .... Nevertheless, the electron bunching seen in this case as opposed to the ...

The FELIX free-electron laser uses short pulses of relativistic electrons produced by an RF accelerator. The design target for the duration of these electron bunches was around 3 ps. In experiments we observed that the bunches emit coherently enhanced spontaneous emission ...

The linear collider project at SLAC contains two damping rings to reduce the emittance of short electron or positron bunches which contain 5 x 10 exp 10 particles per bunch. Two of these bunches are stored at a time and then extracted for acceleration in ...

Laser induced bunch lengthening has been measured on the ACO Storage Ring Free Electron Laser (SRFEL) in the anomalous bunch lengthening regime. The experimental results show correlations between the appearance of coherent modes in the electron bunch and anomalous behavior in the presence of ...

In recent years, there has been increasing interest in short electron bunches for different applications such as short wavelength FELs, linear colliders, and advanced accelerators such as laser or plasma wakefield accelerators. One would like to meet various requirements such as high peak current, low momentum ...

The process of wake-field excitation in plasma by sequence of electron bunches is considered theoretically. The dependence of the magnitude of fields from the number of bunches in the pulse is considered also. The reason for the wake-field saturation is determined. The pulse of electrons of energy 2 MeV, of current ...

We study numerically the excitation of plasma wakefields by a train of electron bunches. The purpose is to find a regime in which the wakefield excited by individual electron bunches add and have a large amplitude and a large transformer ratio. This scheme will produce a high energy accelerated ...

Some of the requirements imposed on future linear accelerators to be used in electron-positron colliders are reviewed, as well as some approaches presently being examined for meeting those requirements. RF sources for use in these linacs are described, as well as wakefields, single bunches, and multiple-bunch ...

We report the use of coherent Smith-Purcell radiation to measure the bunch length of femtosecond-scale, 15 MeV electron bunches produced by a 17 GHz rf accelerator. The Smith-Purcell radiation was produced by passing a train of electron bunches above a metal grating. The ...

A new scheme of electron acceleration, employing relativistic electron bunches in a cold plasma, is analyzed. The wake field of a leading bunch is derived in a single-particle model. We then extend the model to include finite bunch length effect. In particular, we discuss ...

The procedure and results of measuring the phase spectrum of accelerated electron bunches are described. At the exit from the accelerator the beam is deflected by the microwave field of a deflector at a frequency different from the bunch repetition frequency, owing to which the entry phase of ...

The current loading in a bunching section with constant structure is considered, when a strong electron phase space motion occurs during the acceleration process. The beam effect was calculated using a self-consistent description of the particle dynamics in a field representing the superposition of the field of the external generator ...

An application accelerator system for monitoring the gain of a free electron laser is disclosed. Coherent Synchrotron Radiation (CSR) detection techniques are used with a bunch length monitor for ultra short, picosec to several tens of femtosec, electron bunches. The monitor employs an ...

An application accelerator system for monitoring the gain of a free electron laser. Coherent Synchrotron Radiation (CSR) detection techniques are used with a bunch length monitor for ultra short, picosec to several tens of femtosec, electron bunches. The monitor employs an application ...

The function of a fifth harmonic (14.28 GHz) bunch monitor is to provide a signal which is proportional to the electron beam bunch size. The monitoring of the rf power signal at 14.28 GHz enables the operator to optimize the rf bunching of the beam at the end of the first accelerating section ...

will be needed to make further progress. Perhaps the most promising is the laser plasma accelerator. A simulation of a laser wakefield acceerator: bunches of electrons...

It is shown that optimal difference of frequencies of following of electron bunches and following of wake-field bubbles exists, so N-1 drive-bunches strengthen chain of wakefield bubbles and N-th bunch gets in maximal accelerating wakefield.

Experiments, and simulations have shown that quasi-monoenergetic electron bunches can be accelerated from the background electron plasma population up to relativistic energies. Theoretical work indicated that with a proper choice of laser, plasma, and injection parameters the acceleration of ...

The Inverse Free Electron (IFEL) and its applications are first briefly reviewed. The concept of harmonic IFEL was proposed for electron beam micro-bunching. A tightly micro-bunched electron beam could be used either as a laser accelerator injector or for...

Focussing ultra-short electron bunches from a laser-plasma wakefield accelerator into an undulator requires particular attention to be paid to the emittance, electron bunch duration and energy spread. Here we present the design and implementation of a focussing system for the ALPHA-X beam ...

Electron beam bunching in the optical wavelength was observed experimentally for the first time at the Brookhaven Accelerator Test Facility (ATF) using the Inverse Free Electron (IFEL) accelerator. The micro-bunched electron beam has been studied by ...

Research into the production and utilization of short electron bunches at Brookhaven National Laboratory is underway at the Source Development Laboratory (SDL) and Accelerator Test Facility (ATF). Projects planned for the SDL facility include a 210 MeV electron linac with a dipole chicane that is designed to ...

The drive linac in Phase I of the Argonne Wakefield Accelerator (AWA) will be used to accelerate short duration (10 ps), high charge (100 nC) electron bunches from 2 MV to 20 MV for use in a variety of wakefield acceleration and measurement studies. The h...

We have developed a new method for measuring the electromagnetic fields (wake fields) induced in high-frequency accelerating devices by intense relativistic electron bunches. These fields are probed by a second collinear electron bunch which follows the primary bunch at a ...

This paper expands on a few important details of the Wakeatron concept. This is a device where electrons can be accelerated by the wake field of short intense proton bunches travelling along the axis of an rf structure. Specifically, we have examined the consequences of the longitudinal dynamics of both the ...

Using a longitudinally dispersive bending-magnet transport system followed by off-phase acceleration in a radio frequency electric field, it is possible to transform a highly relativistic electron bunch such that the relative time coordinate within the initial bunch is uniquely mapped to the relative energy ...

The electron cloud in positron storage rings is pinched when a bunch passes by. For short bunches, the radiation due to acceleration of electrons of the cloud is coherent. Detection of such radiation can be used to measure the density of the cloud. The estimate of the power and the time ...

We have measured the wake fields induced by short, intense relativistic electron bunches in a slow wave structure consisting of a dielectric-lined tube, as a test of the dielectric wake-field acceleration mechanism. These fields were used to accelerate a second electron ...

Recent experiments have explored the use of a free-electron laser (FEL) as a buncher for a microwave two-beam accelerator, and the subsequent driving of a standing-wave rf output cavity. Here the authors present a deeper analysis of the longitudinal dynamics of the electron bunches as they are transported from the ...

Companion development of ultrafast electron beam diagnostics capable of noninvasively resolving single bunch detail is essential for the development of high energy, high brightness accelerator facilities and associated beam-based light source applications. Existing conventional accelerators can exhibit ...

Theory is presented for excitation of hybrid electric/magnetic (HEM) wake-field modes by passage of an electron drive bunch in a dielectric-lined cylindrical waveguide. The drive bunch is moving parallel to the waveguide axis, but is displaced by a radial increment r{sub 0}. Knowledge of the amplitudes of all HEM modes allows ...

In the design of future linear colliders, it will be important to minimize the loss of beam energy due to the excitation of higher-order modes in the accelerator structure by single bunches of electrons or positrons. This loss is not only detrimental in i...

The lasertron rf generator uses an rf-modulated laser beam to generate a tightly bunched electron beam that is accelerated by a dc power supply to the fractional megawatt region. The tightly bunched beam then crosses an output cavity where most of the kin...

This paper discusses a novel idea to accelerate low-intensity bunches of electrons (or positrons) by the wake field of intense proton bunches travelling along the axis of a cylindrical rf structure. Accelerating gradients in excess of 100 MeV/m and large ''transformer ...

Both self-acceleration and laser-acoustic acceleration in crystals are considered. The conduction electrons in the crystal are treated as a plasma and are the medium through which the acceleration takes place. Self-acceleration is the possible acceleration of part of a ...

The resonant excitation of plasma wakefields by a train of equidistant electron bunches can lead to large energy loss and energy gain. The bunch train can in principle also be tailored to produce a large transformer ratio R (>>2). The energy gain by a witness bunch can in principle reach R times the drive ...

Production of a monoenergetic electron bunch in a self-injected laser-wakefield accelerator is investigated with a tomographic method which resolves the electron injection and acceleration processes. It is found that all the electrons in the monoenergetic ...

Recently, producing and maintaining short bunches in accelerators has become a forefront issue. Examples of accelerators that require short bunches are high quality nuclear physics accelerators, free electron laser driver accelerators, next generation ...

The Vavilov-Cherenkov radiation generated by a relativistic electron bunch that propagates in the vacuum channel of a rectangular dielectric-filled wakefield accelerating structure is analytically described. The approach is based on the expansion of wake fields in terms of the eigenfunctions of operators of the transverse electric and ...

The main goal at the Accelerator Test Facility (ATF) at the KEK laboratory in Japan is to develop the technology that can stably supply the main linac with an extremely flat multi-bunch beam. The injector for this accelerator was upgraded to produce greater than 2 x 10{sup 10} in electrons a single ...

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 ...

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 ...

The Argonne Wakefield Accelerator group develops accelerating structures based on dielectric loaded waveguides. We use high charge short electron bunches to excite wakefields in dielectric loaded structures, and a second (low charge) beam to probe the wakefields left behind by the drive beam. We report measurements ...

The Argonne Wakefield Accelerator facility has begun its experimental program. It is designed to address advanced acceleration research requiring very short, intense electron bunches. It incorporates two photocathode based electron sources. One produces u...

We examine the re-acceleration of a bunched beam through a linear induction accelerator (LIA) cavity, with attention to the energy lost through coupling to the TM modes of the structure. We find that the energy lost at 1 kA peak current is a small fraction of the boost which the LIA is designed to impart. We discuss implications for a ...

A theoretical model was developed to explain observations of collective ion acceleration in linear systems. A linearized calculation for the pinch mechanism considered is carried out using the two mass approximation for the relativistic electron beam. This model differs from the picture previously constructed in that the polarization charge due to Cerenkov ...

Electron bunches with the unparalleled combination of high charge, low emittances, and short time duration, as first produced at the SLAC Final Focus Test Beam (FFTB), are foreseen to be produced at the SABER facility. These types of bunches have enabled ...

A photocathode electron source for the Argonne Wakefield accelerator is being designed to produce a number of short (10 psec), 100 nC bunches per rf pulse. Possible sources of fluctuations in the position and energy of these bunches are variations in the ...

As part of the design effort for a free electron laser driven by the Next Linear Collider Test Accelerator (NLCTA), the author reports studies of bunch- length compression utilizing the existing infrastructure and hardware. In one possible version of the ...

The bunch shape of single-bunch electron beams, generated with a 38 MeV L-band linear accelerator, was evaluated using the longitudinal bunch form factor at the Institute of Scientific and Industrial Research at Osaka University. The single-bunch beams are being used in ...

In this paper the authors discuss the generation of ultra-short electron bunches using laser-driven RF guns. The designs are tailored for future plasma accelerators. Second generation plasma accelerators are expected to be very demanding in terms of bunch length, since the ...

In the SLC main linac a train of three bunches is accelerated. The leading positron bunch is followed by two bunches of electrons. When the positron bunch passes off-axis through the Rf structures, it excites dipole modes in the structures, for example long-range transverse ...

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 ...

Laser induced bunch lengthening has been measured on the ACO Storage Ring Free Electron Laser (SRFEL) in the anomalous bunch lengthening regime. The experimental results show correlations between the appearance of coherent modes in the electron bunch and anomalous behavior in the presence of ...

The intensity of the accelerated single bunched electron beam depends on the performance of the electron gun and the fast cathode pulser. The electron beam is emitted by a Y-796 cathode assembly with a cathode of 2 cm2 (8 A/cm2), and an extracted voltage of 90 kV. The maximum charge of the ...

An analytic formalism of cumulative beam breakup in linear accelerators is developed. This formalism is applied to both low-velocity ion accelerators and high-energy electron accelerators. It includes arbitrary velocity, acceleration, focusing, initial conditions, beam-cavity resonances, finite ...

In high charge RF photoinjectors for wakefield two beam acceleration studies, due to the strong longitudinal space charge, bunch lengthening between the photocathode and photoinjector exit is a critical issue. We present beam dynamics studies of bunch lengthening in an RF photoinjector for a high charge electron ...

A combination klystron-linear accelerator which utilizes anti-bunch electrons generated in the klystron section as a source of electrons to be accelerated in the accelerator section. Electron beam current is controlled by second harmonic ...

Dielectric loaded wakefield structures have potential to be used as high gradient accelerator components. Using the high current drive beam at the Argonne Wakefield Accelerator Facility, we employed cylindrical dielectric loaded wakefield structures to generate accelerating fields of up to 86 MV/m, at 10 GHz. Short ...

Dielectric loaded wakefield structures have potential to be used as high gradient accelerator components. Using the high current drive beam at the Argonne Wakefield Accelerator Facility, we employed cylindrical dielectric loaded wakefield structures to generate accelerating fields of up to 86 MV/m, at 10 GHz. Short ...

Experimental results are reported from two measurementtechniques (semiconductor switching and electro-optic sampling) thatallow temporal characterization of electron bunches produced by alaser-driven plasma-based accelerator. As femtosecond electron bunchesexit the plasma-vacuum interface, coherent transition ...

For every cycle of the SLC, the injector is required to launch two electron bunches and a single positron bunch into their respective emittance damping rings. Each bunch is to have a population of 7.5 x 10/sup 10/ particles/bunch, an energy of 1.21 GeV, and a full width energy spread of less ...

The transformer ratio R is a parameter that characterizes the efficiency of the energy transferred from the drive beam to the trailing witness beam passing through a wakefield accelerating structure (all metal or dielectric based) or a plasma chamber. Using a ramped bunch train (RBT) rather than a single drive bunch, the enhanced ...

The transformer ratio R is a parameter that characterizes the efficiency of the energy transferred from the drive beam to the trailing witness beam passing through a wakefield accelerating structure (all metal or dielectric based) or a plasma chamber. Using a ramped bunch train (RBT) rather than a single drive bunch, the enhanced ...

The transformer ratio R is a parameter that characterizes the efficiency of the energy transferred from the drive beam to the trailing witness beam passing through a wakefield accelerating structure (all metal or dielectric based) or a plasma chamber. Using a ramped bunch train (RBT) rather than a single drive bunch, the enhanced ...

The diagnostics of ultrashort electron bunches developed basing on undulator and synchrotron radiation in the framework of the JINR-DESY collaboration is designated for the International Linear Collider (ILC) project, as well as for Free Electron Lasers (FELs) such as the FLASH and X ray XFEL laser. All these ...

An adiabatic free-electron laser wiggler for electron beam bunching is described. A free-electron laser naturally bunches an electron beam. When the beam is trapped adiabatically, the emittance of the bunched beam is decreased significantly compared ...

The effects of coherently enhanced radiation reaction on the motion of subwavelength electron bunches in interaction with intense laser pulses are analyzed. The radiation reaction force behaves as a radiation pressure in the laser beam direction, combined with a viscous force in the perpendicular direction. Due to Coulomb expansion of the ...

A single-pass high-gain x-ray free electron laser (FEL) calls for a high quality electron bunch. In particular, for a seeded FEL amplifier and for a harmonic generation FEL, the electron bunch initial energy profile uniformity is crucial for generating an FEL with a narrow bandwidth. After the ...

Details on the generation of (multiple) quasimonoenergetic electron bunches in the self-modulated laser wakefield acceleration (SMLWFA) regime are presented. This type of laser-plasma interaction can result in pronounced longitudinal laser pulse fragmentation, dependent on plasma density and laser intensity. It is shown by experiments ...

Facilities for Accelerator Science and Experimental Test Beams (FACET) is a proposed facility at SLAC that would use the initial two-thirds of the linac to transport e{sup +} and e{sup -} beams to an experimental region. A principal use of this facility is to identify the optimum method for accelerating positrons in a beam driven plasma wakefield ...

An analytical theory for the interaction of an electron bunch with a nonlinear plasma wave is developed to make it possible to design efficient laser- and/or beam-driven accelerators that generate high quality monoenergetic electron beams. This theory shows how to choose the charge, the shape, and the placing of ...

This paper reports on design and construction features of a bunching system built at the Naval Research Laboratory (NRL) for the NRL linac, with emphasis on solution of the impedance matching and tuning problems inherent in the buncher design.

Coherent radiation emitted from a relativistic electron bunch consists of wavelengths longer than or comparable to the bunch length. The intensity of this radiation out-numbers that of its incoherent counterpart, which extends to wavelengths shorter than the bunch length, by a factor equal to the number of ...

We present a practical method for achieving a transformer ratio (R) greater than 2 with any collinear wakefield accelerator--i.e. with either plasma or structure based wakefield accelerators. It is known that the transformer ratio cannot generally be greater than 2 for a symmetric drive bunch in a collinear wakefield ...

Recent studies of the scaling laws and economic feasibility of very-high-energy linear accelerators suggest the use of very-short-wavelength accelerating structures. Consideration is being given to the use of electromagnetic driving fields of centimeter, millimeter, and even micron wavelengths. As we scale down to smaller dimensions, the use of open ...

Estimations are given for possible longitudinal coupled-bunch instabilities due to non-accelerating modes of a multi-cell pi -mode accelerating structure. When every bucket in the ring is filled with electrons, some cavity modes in the fundamental passban...

A scheme for accelerating electrons is proposed which uses a bunched relativistic electron beam in a cold plasma. Lasers are not required, and large energy gradients (exceeding 1 GeV/m) are attained. As in the two-stream instability, the streaming relativistic electrons lose energy to the ...

We observed the bunch structure of the circulating beam in the 1.3-GeV Electron Synchrotron (ES) for the first time. The ES operated at a repetition rate of 21 Hz and an rf frequency of 138 MHz. The bunch length variation during the rf acceleration were d...

At the DESY TTF2 linear accelerator three special techniques to characterize the longitudinal charge distribution of the electron bunches that drive the free-electron laser are currently under study: electro-optical sampling, far-infrared spectral analysis of coherent radiation and the use of a transverse ...

Recent advances in laser-plasma accelerators, including the generation of GeV-scale electron bunches, enable applications such as driving a compact free-electron laser (FEL). Significant reduction in size of the FEL is facilitated by the expected ultrahigh peak beam currents (10-100 kA) generated in laser-plasma ...

The minimum bunch length achievable using a magnetic bunch compression system is related to the nonlinear dispersion of the compressor and the nonlinear energy-phase correlation of the bunch's longitudinal phase space. For electron bunches with medium or high charge (on the order of 1 nC, or ...

We report turn-by-turn observation of coherent synchrotron radiation (CSR) produced by the laser bunch slicing technique at an electron storage ring operated with a small momentum compaction factor. CSR emission was intermittent, and its interval depended strongly on the betatron tune. This peculiar behavior of the CSR could be interpreted as a result of ...

The second harmonic of the laser light (2omega(0)) is observed on the rear side of thick solid targets irradiated by a laser beam at relativistic intensities. This emission is explained by the acceleration by the laser pulse in front of the target of short bunches of electrons separated by the period (or half the period) of the laser ...

We have augmented the code POSINST to include solenoid fields and used it to simulate the buildup of electron cloud due in the PEP-II positron ring. We find that the distribution of electrons is strongly affected by the resonances associated with the cyclotron period and bunch spacing. In addition, we discover a threshold beyond which ...

We have augmented the code POSINST to include solenoid fields, and used it to simulate the build up of electron cloud due in the PEP-II positron ring. We find that the distribution of electrons is strongly affected by the resonances associated with the cyclotron period and bunch spacing. In addition,we discover a threshold beyond which ...

The Plasma and Beam Physics Research Facility at Chiang Mai University has established a THz facility to focus on the study of ultra-short electron pulses. Short electron bunches can be generated from a system that consists of a radio-frequency (RF) gun with a thermionic cathode, an alpha magnet as a magnetic bunch ...

A FEL of average power 200 kW is being designed at the LBNL for satellite power beaming. It utilizes the radiation of {approximately} 100 MeV electrons with {approximately} 200 A peak current. In order to obtain the desired peak current, the 5mm long electron bunches delivered by a linear accelerator are ...

Electron acceleration, in vacuum, mediated by an intense echelon phase-modulated long Gaussian laser pulse, is investigated here. Theoretical and numerical analyses show that this pulse can accelerate an electron to much higher energies than an unmodulated pulse. The staircase-like phase structure of the laser ...

The DUVFEL electron linac is designed to produce sub-picosecond, high brightness electron bunches for driving a short wavelength FEL. Four experiments have been commissioned to address the challenge of accurately measuring bunch lengths on this timescale. In the frequency domain, a short 12 period undulator is used ...

In order to reach the high peak current required for an x-ray FEL, two separate magnetic dipole chicanes are used in the LCLS accelerator to compress the electron bunch length in stages. In these bunch compressors, coherent synchrotron radiation (CSR) can be emitted-induced either by a short ...

Bunch length and energy-z correlation measurements were performed on the high energy (28.5 GeV) electron test beam of the A-line and End Station A (ESA) facilities at the SLAC National Accelerator Laboratory. The longitudinal profile of each bunch was measured by imaging the synchrotron light emitted as the ...

The authors explore the generation of short electron bunches from a field-emitter array cathode consisting of nanometer-sized metallic tips that is compatible with an acceleration electric field above 10 MV/m. Sub-nanosecond field emission electron bunches were generated by applying fast ...

A scheme is proposed to produce high-quality quasi-monoenergetic attosecond electron bunches based on laser ponderomotive-force acceleration along the surface of wire or slice targets. Two- and three-dimensional particle-in-cell simulations demonstrate that the electron energy depends weakly on the target density. ...

A plasma channel is a narrow preionized column of plasma that can be used for a number of accelerator applications. Plasma channels play a crucial role in the laser wakefield accelerator (LWFA), where they may provide the acceleration medium as well as guiding of the intense laser pulse and accelerated ...

Measurements of coherent diffraction radiation from a slit of variable width generated by short electron bunches were performed in millimeter and submillimeter ranges. Experimental data are compared with the transition radiation case and theoretical predictions. A more realistic description than the conventional theory is necessary to account for the data ...

Uniform three-dimensional ellipsoidal distributions of charge are the ultimate goal in charged particle accelerator physics because of their linear internal force fields. Such bunches remain ellipsoidal with perfectly linear position-momentum phase space correlations in any linear transport system. We present a method, based on photoemission by radially ...

The longitudinal charge distribution of short electron bunches can be characterized by a measurement of their coherent far-infrared radiation spectrum. This paper will present the results obtained at the DESY VUV-FEL linear accelerator by observation of synchrotron radiation with a Martin-Puplett interferometer. The reconstructed ...

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, ...

Numerical calculations are made to determine the h-f amplitude damping increased by beam loading, the variation of the phase length of the electron bunch with respect to the wave, and the energy increase of the electron. In the calculations which are carried out for one section of the accelerator it is ...

A Two-Beam Accelerator, in which one of the beams is an intense low energy beam made to undergo free electron lasing and the other beam is a compact bunch of high energy electrons, is shown to be an interesting possibility for a linear collider.

The electron cloud effect (ECE) causes beam instabilities in accelerator structures with intense positively charged bunched beams. Reduction of the secondary electron yield (SEY) of the beam pipe inner wall is effective in controlling cloud formation. We ...

We propose a novel method for tailoring the current distribution of relativistic electron bunches. The technique relies on a recently proposed transverse-to-longitudinal phase space exchange. The bunch is transversely shaped and the phase space exchange mechanism converts this transverse profile into a current profile. The technique ...

We proposed a novel method for tailoring the current distribution of relativistic electron bunches. The technique relies on a recently proposed transverse-to-longitudinal phase space exchange. The bunch is transversely shaped and the phase space exchange mechanism converts this transverse profile into a current profile. The technique ...

We proposed a novel method for tailoring the current distribution of relativistic electron bunches. The technique relies on a recently proposed transverse-to-longitudinal phase space exchange. The bunch is transversely shaped and the phase space exchange mechanism converts this transverse profile into a current profile. The technique ...

A bunch length monitor for ultrashort (90 fs to 1 ps) electron bunches using a coherent synchrotron radiation detection techniques has been developed in a collaboration between the Thomas Jefferson National accelerator Facility (Jefferson Lab) and the University of Virginia. The noninvasive, high-resolution, ...

For the generation of intense single and multiple bunches of electrons (> 8 nc per bunch) for accelerator studies at SLAC, a high peak current photoemission electron gun has been developed. A gallium arsenide photocathode is illuminated by the optical bea...

The ion response to relativistic electron bunches in the so called bubble or blowout regime of a laser-plasma accelerator is discussed. In response to the strong fields of the accelerated electrons the ions form a central filament along the laser axis that can be compressed to densities 2 ...

We explore in this note the idea of accelerating a low intensity electron or positron bunch, travelling through a linear rf structure, following at a short distance an intense proton bunch which leaves behind a wake field. This device acts like a transformer where two beams are involved: one made of protons at ...

A new concept of double-decker electron beam accelerator based on a photocathode radio-frequency (rf) gun was proposed for studying chemical kinetics and primary processes or reactions of radiation chemistry. The synchronized double-decker electron beams with time interval of 1.4 ns were generated in the rf gun by injecting two laser ...

A new concept of double-decker electron beam accelerator based on a photocathode radio-frequency (rf) gun was proposed for studying chemical kinetics and primary processes or reactions of radiation chemistry. The synchronized double-decker electron beams with time interval of 1.4 ns were generated in the rf gun by injecting two laser ...

A photoinjector is being constructed in order to produce a pulse train of up to 800 electron bunches, each with 8 nC of charge and a 3.5 ps rms bunch length. The spacing between bunches within a train is 1 s and the train repe-tition rate is 1?10 Hz. The desired transverse emittance is <20 mm mrad. An rf ...

... Development of a linear accelerator for production of a bunched ... This accelerator was ... Calibration of an analyzing magnet intended to produce, by ...

Electron bunches produced in self-modulated laser wakefield experiments usually have a broad energy spectrum, with most electrons at low energy (1-3 MeV) and only a small fraction at high energy. We propose and investigate further acceleration of such bunches in a channel-guided resonant laser ...

Several theories have been proposed to explain anomalous bunch lengthening and widening in particle storage rings. All these theories either assume a modification of the accelerating potential well or a high frequency self-bunching mechanism similar to the one proposed for proton bunches. Some of the theories ...

A new method is proposed for collectively accelerating bunches of ions with an intense relativistic-electron beam. By varying the beam energy in time, acceleration of a slow Doppler-shifted cyclotron wave can be accomplished, without accompanying degradation of the beam equilibrium. Test-particle calculations ...

Previous experiments on FFTB at SLAC demonstrated that short electron bunches can produce accelerating gradient of 50 GeV/m over one meter[1]. These experiments provided the science case for the new FACET facility which will have 23 GeV high current beams. Two-bunch PWFA experiment has a second ...

One of the steps involved in producing an intense ion beam from conventional accelerators for Heavy Ion Fusion (HIF) is beam bunching. To maintain space charge neutralized transport, neutralization must occur more quickly as the beam bunches. It has been demonstrated at BNL that a 60 mA proton beam from a 750 kV Cockcroft--Walton can ...

The authors investigate the stability of the driving electron or positron beam in the plasma wakefield accelerator (PWFA). Although the beam is subject to self-focusing, filamentation, and two-stream instability, they find that all of these can be stabilized by introducing thermal energy and an axial magnetic field.

This paper expands on a few important details of the Wakeatron concept. This is a device where electrons can be accelerated by the wake field of short intense proton bunches travelling along the axis of an rf structure. Specifically, we have examined the ...

Induction linacs are among the most powerful accelerators in existence. They have accelerated electron bunches of several kiloamperes, and are being investigated as drivers for heavy ion driven inertial confinement fusion (HIF), which requires peak beam c...

The collective acceleration mechanism of protons and nuclei in solar flares, which lies in the fact that nuclei are trapped by electron bunches moving along the opened lines of force of the decreasing magnetic field of solar sports, is discussed. The prop...

Recent experiments have explored the use of a free-electron laser (FEL) as a buncher for a microwave two-beam accelerator, and the subsequent driving of a standing-wave rf output cavity. Here the authors present a deeper analysis of the longitudinal dynam...

The Sub-Picosecond Accelerator (SPA) at the Los Alamos National Laboratory is an L-band photoinjector. Using magnetic compression, the SPA routinely compresses 8 MeV, 1 nC per bunch electron beams from an initial temporal FWHM bunch length of 20 ps to less than 1 ps. In recent plasma wakefield ...

The temporal profile of relativistic laser-plasma-accelerated electron bunches has been characterized. Coherent transition radiation at THz frequencies, emitted at the plasma-vacuum boundary, was measured through electro-optic sampling. Frequencies up to the crystal detection limit of 4 THz were observed. Comparison between data and ...

Dielectric loaded wakefield structures have potential to be used as high gradient accelerator components. Using the high current drive beam at the Argonne Wakefield Accelerator Facility, we employed cylindrical dielectric loaded wakefield structures to generate accelerating fields of up to 100 MV/m. Short electron ...

A free electron laser (FEL) is provided with an accelerator for outputting electron beam pulses; a buncher for modulating each one of the electron beam pulses to form each pulse into longitudinally dispersed bunches of electrons; and a wiggler for generating coherent light ...

A free electron laser (FEL) is provided with an accelerator for outputting electron beam pulses; a buncher for modulating each one of the electron beam pulses to form each pulse into longitudinally dispersed bunches of electrons; and a wiggler for generating coherent light ...

The laser undulator compact X-ray source (LUCX) is a test bench used with the compact, high-brightness X-ray generator at KEK (High Energy Accelerator Research Organization). Our group is conducting experiments with LUCX to demonstrate the possibility of K-edge digital subtraction angiography, based on Compton scattering. One of the challenging problems is to generate ...

The Brookhaven Accelerator Test Facility (ATF) is a 50-MeV electron linac designed to produce electron bunches which can be synchronized with the picosecond pulse of a 100-GWatt CO/sub 2/ laser. This facility will be used to study the acceleration of electrons by the ...

The mechanism of longitudinal interaction of high-energy positrons of a bunch train and secondary emitted particles of electron cloud is analyzed. We consider the case when electron cloud in solenoidal magnetic field is built mainly due to multipacting process. Positron bunches have to use some amount of their ...

Plasma-based accelerators have the ability to sustain extremely large accelerating gradients, with possible high-energy physics applications. This dissertation further develops the theory of plasma-based accelerators by addressing three topics: the performance of a hollow plasma channel as an accelerating ...

-state lasers could meet the requirements for next generation high-gradient particle acceleration. In addition to high gradient operation, a laser- driven accelerator should produce ultra-short elec- tron bunches electron bunch length, on the order of subfemtosecond, is desirable for generating ...

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 ...

Novel acceleration concepts such as laser- or beam-driven plasma acceleration require advanced diagnostic techniques to characterize and monitor the beam. A particular challenge is to measure bunch lengths of the order of 10 femtoseconds. Several methods are currently explored at the free-electron laser FLASH at ...

The design of the linac delivering electron bunches into ten independent soft x-ray free electron lasers (FELs) producing light at 1 nm and longer wavelengths is presented. The bunch repetition rate in the linac is 1 MHz and 100 kHz in each of ten FEL beam lines. Various issues regarding machine layout and ...

The 28 GeV proton synchrotron (PS) forms part of the chain of LEP injectors with the role of accelerating positrons and electrons from 0.6 GeV, the operating energy of the Electron/Positron Accumulator (EPA), to 3.5 GeV, the positron/electron injection energy of CERN's 400 GeV proton synchrotron (SPS) ...

Positron beam position measurement for the Advanced Photon Source (APS) linac beam is affected by the presence of electrons that are also captured and accelerated along with the positrons. This paper presents a method of measuring positron position in a beam consisting of alternating bunches of positrons and ...

Bunch driven plasma wakefield accelerators (PWFA), such as the 'plasma afterburner', are a promising emerging method for significantly increasing the energy output of conventional particle accelerators. The study and optimization of this method would benefit from an experimental correlation of the drive ...

The plasma wakefield accelerator (PWFA) is an accelerator concept based on utilizing a large amplitude plasma wave to accelerate relativistic electrons to ultra-high energy. The plasma wave represents the wave produced by a relativistic beam as it passes through a cold plasma. As the beam enters the plasma its ...

The electron, positron, and photon acceleration in the first cycle of a laser-driven wakefield is investigated. Separatrices between different types of the particle motion (trapped, reflected by the wakefield and ponderomotive potential, and transient) are demonstrated. The ponderomotive acceleration of electrons ...

Laser plasma accelerators are able to produce high quality electron beams from 1 MeV to 1 GeV. The next generation of plasma accelerator experiments will likely use a multi-stage approach where a high quality electron bunch is first produced and then injected into an ...

In this paper we propose a multi-stage wake field acceleration scheme to overcome the low transformer ratio problem and still provide high accelerating gradients. The idea is very simple. We use a train of several electron bunches from a linear accelerator (main linac) with well defined ...

A new accelerator, LACARA (laser-driven cyclotron autoresonance accelerator), under construction at the Accelerator Test Facility at Brookhaven National Laboratory, is to be powered by a 1 TW CO2 laser beam and a 50 MeV injected electron pulse. LACARA will produce inside a 2 m, 6 T solenoid a 100 MeV gyrating ...

Longitudinal bunching properties of a classical microtron have been investigated by the numerical simulation of the longitudinal motion of accelerated electrons. The simulations were performed for the 12-turn microtron that has been used as an injector for the KAERI far infrared free electron laser. Based on the ...

In a plasma wakefield accelerator (PWFA) with a drive bunch density higher than the plasma, a pure ion column is formed behind the drive bunch (blow-out regime). Due to the ion restoring force, which is linearly increasing with radius, beam electrons perform betatron oscillations. We consider the case of a witness ...

The main injector for the 4 GeV CEBAF accelerator at Thomas Jefferson National Accelerator Facility was designed to deliver simultaneously three CW electron beams for nuclear physics research. The maximum design current for a single beam from the injector is 100 ?A, or 0.2 pC per microbunch at a repetition rate of 499 MHz. It was found ...

We report the development of a nondestructive technique to measure bunch rms length in the psec range and below, and eventually in the fsec range, 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. We demonstrate ...

At the SLC, a train consisting of one positron bunch followed by two electron bunches is accelerated in the linac, each separated by about 60 ns. Long-range transverse wakefields from the leading bunch were found to cause up to a factor of three increase in beam jitter for the trailing ...

The International Linear Collider (ILC) is a proposed electron-positron collider, expected to provide insight into important questions in particle physics. A part of the global R&D effort for the ILC is the design of its electron gun and electron bunching system. The present design of the ...

Coherent radiation in the 0.3-3 THz range has been generated from femtosecond electron bunches at a plasma-vacuum boundary via transition radiation. The bunches produced by a laser-plasma accelerator contained 1.5 nC of charge. The THz energy per pulse within a limited 30 mrad collection angle was 3-5 nJ and scaled ...

Coherent radiation in the 0.3 - 3 THz range has been generated from femto second electron bunches at a plasma-vacuum boundary via transition radiation. The bunches produced by a laser-plasma accelerator contained 1.5 nC of charge. The THz energy per pulse within a limited 30 mrad collection angle was 3.5 nJ and ...

The concept of the Lasertron can be most easily described by referring to the figures. A short bunch of electrons (short in time compared to the period of an rf cycle), is emitted from the cathode and accelerated by a dc potential toward the anode. An rf cavity, located just past the anode aperture, is the output cavity. The rf ...

Cumulative beam breakup in linear accelerators has been studied extensively for the case of infinitely short bunches. While this model is appropriate for high energy accelerators, in high-current ion accelerators the bunch length can occupy a significant ...

These days the linac at the Stanford Linear Accelerator Center (SLAC) is mainly an injector for the PEP-II rings. But besides the electrons and positrons for PEP-II, it provides a 30 GeV electron or positron beam to the end of the linac into the FFTB (Final Focus Test Beam) area or creates a test beam for the A-Line. In the FFTB tunnel ...

LBNL is currently pursuing a collider design based on meter-long 10 GeV laser-plasma accelerator stages, and Thomson gamma source designs at �1 GeV, that will operate in the quasi-linear regime. This regime allows symmetric acceleration of electrons and positrons and has the property that the transverse fields are proportional to the ...

Excitation of wakefields from a short charge bunch moving parallel to the axis of a dielectric-lined cylindrical waveguide is analyzed. This situation amounts to generation of Cerenkov radiation in a transversely bounded system. Wakefields are expanded into an orthonormal set of hybrid electric-magnetic eigenfunctions for this waveguide geometry. The orthonormalization ...

Excitation of wakefields from a short charge bunch moving parallel to the axis of a dielectric-lined cylindrical waveguide is analyzed. This situation amounts to generation of Cerenkov radiation in a transversely bounded system. Wakefields are expanded into an orthonormal set of hybrid electric-magnetic eigenfunctions for this waveguide geometry. The orthonormalization ...

The phase stability in the capture and acceleration scenario (CAS) is studied and compared with that of conventional linear electron accelerators (CLEAs). For the CAS case, it has been found that a slow phase slippage occurs due to the difference between the electron velocity and the phase velocity of the ...

Slow feedback has been developed to control the energy and energy spread of the beams which are injected into the SLC damping rings. Within a single RF pulse, two bunches of electrons and one bunch of positrons are accelerated to an energy of 1.21 GeV in the injector of the SLC. The two ...

We present analytical studies of electron acceleration in the low-density preplasma of a thin solid target by an intense femtosecond laser pulse. Electrons in the preplasma are trapped and accelerated by the ponderomotive force as well as the wake field. Two-dimensional particle-in-cell simulations show that when ...

The Coherent Synchrotron Radiation (CSR) could be a concern in many modern accelerator projects. In the proposed electron-cooling project for the Relativistic Heavy Ion Collider (RHIC), the electron cooler is designed to cool 100 GeV/nucleon bunched ion-beam using 55 MeV electrons. The ...

Power extraction using a dielectric-loaded (DL) waveguide is a way to generate high-power radio frequency (RF) waves for future particle accelerators, especially for two-beam-acceleration. In a two-beam-acceleration scheme, a low-energy, high-current particle beam is passed through a deceleration section of waveguide (decelerator), ...

The testing of the upgrade prototype for the bunch current monitors (BCMs) in the PEP-II storage rings at the Stanford Linear Accelerator Center (SLAC) is the topic of this paper. Bunch current monitors are used to measure the charge in the electron/positron bunches traveling in particle ...

A measurement of the longitudinal beam profile of a relativistic charged particle beam is an important tool in modern accelerators. For bunch lengths in the range of picoseconds, such measurements can be performed by means of a streak camera. Shorter bunches usually require special techniques. In this paper we describe a novel ...

A relativistic electron beam moving in a circular orbit in free space can radiate coherently if the wavelength of the synchrotron radiation exceeds the length of the bunch. In accelerators coherent radiation of the bunch is usually suppressed by the screening effect of the conducting walls of the vacuum chamber [1, ...

Production of a monoenergetic electron bunch in a self-injected laser-wakefield accelerator is investigated with a tomographic method which resolves the electron injection and acceleration processes. It is found that all the electrons in the monoenergetic ...

It is shown that the fields generated by relativistic electron (positron) bunches moving in overdense cold plasma have two components -- wake and Coulomb. The existence of the Coulomb component is caused by the absence of the Debay screening of the charge moving in plasma with the velocity greater than the thermal velocity of the plasma ...

The observation and modeling of coherent transition radiation from femtosecond laser accelerated electron bunches is discussed. The coherent transition radiation, scaling quadratically with bunch charge, is generated as the electrons transit the plasma-vacuum boundary. Due to the limited ...

The observation and modeling of coherent transition radiation from femtosecond laser-accelerated electron bunches is discussed. The coherent transition radiation, scaling quadratically with bunch charge, is generated as the electrons transit the plasma-vacuum boundary. Due to the limited ...

This paper presents the results of electron beam tracking simulations with the ASTRA code for the 312 cell superconducting RF gun at the Forschungszentrum Dresden-Rossendorf. The SRF gun will improve the quality of the electron beam parameters for the ELBE superconducting electron linear accelerator. The ELBE ...

Experiments [1], and simulations[2] have shown that quasi-monoenergetic electron bunches can be accelerated from the background electron plasma population up to relativistic energies. Theoretical work [3] indicated that with a proper choice of laser, plasma, and injection parameters the ...

An analytical model for the self-modulation instability of a long relativistic proton bunch propagating in uniform plasmas is developed. The self-modulated proton bunch resonantly excites a large amplitude plasma wave (wakefield), which can be used for acceleration of plasma electrons. Analytical expressions for ...

An analytical model for the self-modulation instability of a long relativistic proton bunch propagating in uniform plasmas is developed. The self-modulated proton bunch resonantly excites a large amplitude plasma wave (wakefield), which can be used for acceleration of plasma electrons. Analytical expressions for ...

Striplines beam position monitors are normally considered low frequency devices with at best an octave bandwidth. Some attempts to make them very high frequency and broadband have led to long and complicated tapered construction. However, conventional uniform coupling striplines can provide very high frequency and broadband response, if the downstream induced signal is gated out ...

Striplines beam position monitors are normally considered low frequency devices with at best an octave bandwidth. Some attempts to make them very high frequency and broadband have led to long and complicated tapered construction. However, conventional uniform coupling striplines can provide very high frequency and broadband response, if the downstream induced signal is gated out ...

The current Laser Electron Acceleration Program (LEAP) seeks to modulate the energy of an electron bunch by interaction of the electrons with a copropagating pair of crossed laser beams at 800 nm. We present an optical injector design for a LEAP cell so that it can be used to give net energy ...

The pick up and acceleration of all plasma electrons irradiated by an intense, subcyclic laser pulse is demonstrated via analytical and numerical calculations. It is shown that the initial low emittance of the plasma electrons is conserved during the process of acceleration, leading to an extremely cold, ...

In the wake-field scheme of particle acceleration, a short, intense drive bunch of electrons passes through a slow-wave structure, leaving behind high rf power in its wake field. The axial accelerating electric field associated with the rf can be quite la...

We report the production of optically spaced attosecond microbunches produced by the inverse Free Electron Laser (IFEL) process. The IFEL is driven by a Ti:sapphire laser synchronized with the electron beam. The IFEL is followed by a magnetic chicane that converts the energy modulation into the longitudinal microbunch structure. The microbunch train is ...

Different methods for diagnostics of ultrashort electron bunches are developed at JINR-DESY collaboration within the framework of the FLASH and XFEL projects and JINR participation in the ILC project. The main peculiarity of these accelerator complexes is related to formation of ultrashort electron ...

The temporal pro le of relativistic laser-plasma-acceleratedelectron bunches has been characterized. Coherent transition radiation atTHz frequencies, emitted at the plasma-vacuum boundary, is measuredthrough electro-optic sampling. The data indicates that THz radiation isemitted by a skewed bunch with a sub-50 fs rise time and a ~; 600 fs ...

A relativistic electron beam moving on a circular orbit in free space can radiate coherently if the wavelength of the synchrotron radiation exceeds the length of the bunch. In accelerators coherent synchrotron radiation (CSR) of the bunch is usually suppressed by the shielding effect of the conducting walls of the ...

A linac configuration providing a low emittance high peak current electron beam is under study for a potential Linac Coherent Light Source (LCLS) based on the SLAC accelerator. The parameters of the final electron bunch are nearing the technological limit...

A linac configuration providing a low emittance high peak current electron beam is under study for a potential Linac Coherent Light Source (LCLS) based on the SLAC accelerator. The parameters of the final electron bunch are nearing the technological limits of present accelerators in both ...