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New Techniques for Particle Acclerators

Description: A review is presented of the new techniques which have been proposed for use in particle accelerators. Attention is focused upon those areas where significant progress has been made in the last two years--in particular, upon two-beam accelerators, wakefield accelerators, and plasma focusers.
Date: June 1, 1990
Creator: Sessler, Andrew M.
Partner: UNT Libraries Government Documents Department

Stable Electron Beams With Low Absolute Energy Spread From a LaserWakefield Accelerator With Plasma Density Ramp Controlled Injection

Description: Laser wakefield accelerators produce accelerating gradientsup to hundreds of GeV/m, and recently demonstrated 1-10 MeV energy spreadat energies up to 1 GeV using electrons self-trapped from the plasma.Controlled injection and staging may further improve beam quality bycircumventing tradeoffs between energy, stability, and energyspread/emittance. We present experiments demonstrating production of astable electron beam near 1 MeV with hundred-keV level energy spread andcentral energy stability by using the plasma density profile to controlselfinjection, and supporting simulations. Simulations indicate that suchbeams can be post accelerated to high energies,potentially reducingmomentum spread in laser acceleratorsby 100-fold or more.
Date: June 25, 2007
Creator: Geddes, Cameron G.R.; Cormier-Michel, E.; Esarey, E.; Leemans,W.P.; Nakamura, K.; Panasenko, D. et al.
Partner: UNT Libraries Government Documents Department

Wake fields and energy spread for the ERHIC ERL

Description: Wake fields in high-current ERLs can cause significant beam quality degradations. Here we summarize effects of coherent synchrotron radiation, resistive wall, accelerating cavities and wall roughness for ERL parameters of the eRHIC project. A possibility of compensation of such correlated energy spread is also presented. An emphasis in the discussion is made on the suppression of coherent synchrotron radiation due to shielding and a possible reduction of wall roughness effects for realistic surfaces.
Date: October 16, 2011
Creator: V., Fedotov A.; Kayran&#44 & D.
Partner: UNT Libraries Government Documents Department

Verification of the AWA Photoinjector Beam Parameters Required for a Transverse-to-Longitudinal Emittance Exchange Experiment

Description: A transverse-to-longitudinal emittance exchange experiment is in preparation at the Argonne Wakefield Accelerator (AWA). The experiment aims at exchanging a low ({var_epsilon}{sub z} < 5 {micro}m) longitudinal emittance with a large ({var_epsilon}{sub x} > 15 {micro}m) transverse horizontal emittance for a bunch charge of {approx}100 pC. Achieving such initial emittance partitioning, though demonstrated via numerical simulations, is a challenging task and needs to be experimentally verified. In this paper, we report preliminary emittance measurements of the beam in the transverse and longitudinal planes performed at {approx}12 MeV. The measurements are compared with numerical simulations.
Date: May 1, 2009
Creator: Rihaoui, M. M.; Piot, P.; Power, J. G.; Mihalcea, D. & Gai, W.
Partner: UNT Libraries Government Documents Department

New modes of particle acceleration, techniques & sources symposium. Summary report

Description: A Symposium on {open_quotes}New Modes of Particle Acceleration Technique and Sources{close_quotes} was held August 19-23, 1996 at the Institute for Theoretical Physics (ITP) in Santa Barbara. This was the first of the 3 symposia hosted by the ITP and supported by its sponsor the National Science Foundation, as part of our {open_quotes}New Ideas for Particle Accelerators{close_quotes} program. The symposia was organized and chaired by Dr. Zohreh Parsa of ITP/Brookhaven National Laboratory. This Symposium provided a perspective on the future direction of the Advanced Accelerator Research. The experimental study of elementary particles has become concentrated at a few large laboratories throughout the world because of the size and cost of the accelerator facilities needed for this work. For example, the Large Hadron Collider (LHC) at CERN, currently under construction, is 27 km in circumference and is being financed by the European membership of CERN plus contributions from non-member nations. An evolutionary approach to construction of ever higher energy colliders will only continue this trend towards high cost and large size.
Date: December 31, 1996
Creator: Parsa, Z.
Partner: UNT Libraries Government Documents Department

GeV electron beams from cm-scale channel guided laser wakefieldaccelerator

Description: Laser-wakefield accelerators (LWFA) can produce electricfields of order 10-100 GV/m suitable for acceleration of electrons torelativistic energies. The wakefields are excited by a relativisticallyintense laser pulse propagating through a plasma and have a phasevelocity determined by the group velocity of the light pulse. Twoimportant effects that can limit the acceleration distanceand hence thenet energy gain obtained by an electron are diffraction of the drivelaser pulse and particle-wake dephasing. Diffraction of a focusedultra-short laser pulse can be overcome by using preformed plasmachannels. The dephasing limit can be increased by operating at a lowerplasma density, since this results in an increase in the laser groupvelocity. Here we present detailed results on the generation of GeV-classelectron beams using an intense femtosecond laser beamand a 3.3 cm longpreformed discharge-based plasma channel [W.P. Leemans et al., NaturePhysics 2, 696-699 (2006)]. The use of a discharge-based waveguidepermitted operation at an order ofmagnitude lower density and 15 timeslonger distance than in previous experiments that relied on laserpreformed plasma channels. Laser pulses with peak power ranging from10-50 TW were guided over more than 20 Rayleigh ranges and high-qualityelectron beams with energy up to 1 GeV were obtained by channelling a 40TW peak power laser pulse. The dependence of the electron beamcharacteristics on capillary properties, plasma density,and laserparameters are discussed.
Date: February 20, 2007
Creator: Nakamura,K.; Nagler, B.; Toth, Cs.; Geddes, C.G.R.; Schroeder,C.; Esarey, E. et al.
Partner: UNT Libraries Government Documents Department

Hosing Instability in the Blow-Out Regime for Plasma-Wakefield Acceleration

Description: The electron hosing instability in the blow-out regime of plasma-wakefield acceleration is investigated using a linear perturbation theory about the electron blow-out trajectory in Lu et al. [in Phys. Rev. Lett. 96, 165002 (2006)]. The growth of the instability is found to be affected by the beam parameters unlike in the standard theory Whittum et al. [Phys. Rev. Lett. 67, 991 (1991)] which is strictly valid for preformed channels. Particle-in-cell simulations agree with this new theory, which predicts less hosing growth than found by the hosing theory of Whittum et al.
Date: February 13, 2008
Creator: Huang, C.; Lu, W.; Zhou, M.; Clayton, C.E.; Joshi, C.; Mori, W.B. et al.
Partner: UNT Libraries Government Documents Department

Hose Instability and Wake Generation By An Intense Electron Beam in a Self-Ionized Gas

Description: The propagation of an intense relativistic electron beam through a gas that is self-ionized by the beam's space charge and wakefields is examined analytically and with 3D particle-in-cell simulations. Instability arises from the coupling between a beam and the offset plasma channel it creates when it is perturbed. The traditional electron hose instability in a preformed plasma is replaced with this slower growth instability depending on the radius of the ionization channel compared to the electron blowout radius. A new regime for hose stable plasma wakefield acceleration is suggested.
Date: April 12, 2006
Creator: Deng, S.; Barnes, C.D.; Clayton, C.E.; O'Connell, C.; Decker, F.J.; Fonseca, R.A. et al.
Partner: UNT Libraries Government Documents Department

Emittance Growth from Multiple Coulomb Scattering in a Plasma Wakefield Accelerator

Description: Emittance growth is an important issue for plasma wakefield accelerators (PWFAs). Multiple Coulomb scattering (MCS) is one factor that contributes to this growth. Here, the MCS emittance growth of an electron beam traveling through a PWFA in the blow out regime is calculated. The calculation uses well established formulas for angular scatter in a neutral vapor and then extends the range of Coulomb interaction to include the effects of traveling through an ion column. Emittance growth is negligible for low Z materials; however, becomes important for high Z materials.
Date: June 27, 2007
Creator: Kirby, N.; Berry, M.; Blumenfeld, I.; Hogan, M.J.; Ischebeck, R.; Siemann, R. et al.
Partner: UNT Libraries Government Documents Department

Emittance exchange results

Description: The promise of next-generation light sources depends on the availability of ultra-low emittance electron sources. One method of producing low transverse emittance beams is to generate a low longitudinal emittance beam and exchange it with a large transverse emittance. Experiments are underway at Fermilab's A0 Photoinjector and ANL's Argonne Wakefield Accelerator using the exchange scheme of Kim and Sessler. The experiment at the A0 Photoinjector exchanges a large longitudinal emittance with a small transverse emittance. AWA expects to exchange a large transverse emittance with a small longitudinal emittance. In this paper we discuss recent results at A0 and AWA and future plans for these experiments.
Date: September 1, 2009
Creator: Fliller, R.P., III; /Brookhaven; Koeth, T. & /Rutgers U., Piscataway
Partner: UNT Libraries Government Documents Department

Observation of transverse space charge effects in a multi-beamlet electron bunch produced in a photo-emission electron source

Description: A 'multiple beamlet' experiment aimed at investigating the transverse space charge effect was recently conducted at the Argonne Wakefield Accelerator. The experiment generated a symmetric pattern of 5 beamlets on the photocathode of the RF gun with the drive laser. We explored the evolution of the thereby produced 5 MeV, space-charge dominated electron beamlets in the 2m drift following the RF photocathode gun for various external focusing. Two important effects were observed and benchmarked using the particle-in-cell beam dynamics code IMPACT-T. In this paper, we present our experimental observation and their benchmarking with Impact-T.
Date: September 1, 2008
Creator: Rihaoui, M.; /Northern Illinois U. /NICADD, DeKalb; Gai, W.; /Argonne; Piot, P.; /Northern Illinois U. /NICADD, DeKalb /FERMILAB et al.
Partner: UNT Libraries Government Documents Department

3-D Simulations of Plasma Wakefield Acceleration with Non-Idealized Plasmas and Beams

Description: 3-D Particle-in-cell OSIRIS simulations of the current E-162 Plasma Wakefield Accelerator Experiment are presented in which a number of non-ideal conditions are modeled simultaneously. These include tilts on the beam in both planes, asymmetric beam emittance, beam energy spread and plasma inhomogeneities both longitudinally and transverse to the beam axis. The relative importance of the non-ideal conditions is discussed and a worst case estimate of the effect of these on energy gain is obtained. The simulation output is then propagated through the downstream optics, drift spaces and apertures leading to the experimental diagnostics to provide insight into the differences between actual beam conditions and what is measured. The work represents a milestone in the level of detail of simulation comparisons to plasma experiments.
Date: September 27, 2005
Creator: Deng, S.; Katsouleas, T.; Lee, S.; Muggli, P.; U., /Southern California; Mori, W.B. et al.
Partner: UNT Libraries Government Documents Department

Betatron radiation from density tailored plasmas

Description: In laser wakefield accelerators, electron motion is driven by intense forces that depend on the plasma density. Transverse oscillations in the accelerated electron orbits produce betatron radiation. The electron motion and the resulting betatron radiation spectrum can therefore be controlled by shaping the plasma density along the orbit of the electrons. Here, a method based on the use of a plasma with a longitudinal density variation (density depression or step) is proposed to increase the transverse oscillation amplitude and the energy of the electrons accelerated in a wakefield cavity. For fixed laser parameters, by appropriately tailoring the plasma profile, the betatron radiation emitted by these electrons is significantly increased in both flux and energy.
Date: April 11, 2009
Creator: Ta Phuoc, Kim; Esarey, E.; Leurent, V.; Cormier-Michel, E.; Geddes, C.G.R.; Schroeder, C.B. et al.
Partner: UNT Libraries Government Documents Department

Design of an electro-optical sampling experiment at the AWA facility

Description: The free space electro-optical (EO) sampling technique is a powerful tool for analyzing the longitudinal charge density of an ultrashort e-beam. In this paper, we present (1) experimental results for a laser-based mock-up of the EO experiment [1] and (2) a design for a beam-based, single-shot, EO sampling experiment using the e-beam from the Argonne Wakefield Accelerator (AWA) RF photoinjector. For the mock-up, a tabletop terahertz experiment is conducted in the AWA laser room. The mock-up uses an IR beam incident on <110> ZnTe crystal to produce a THz pulse via optical rectification. Detection is based on the cross correlation between the THz field and the probe IR laser field in a second <110> ZnTe crystal.
Date: June 1, 2007
Creator: Ruan, J.; Edwards, H.; Tan, Cheng Yang; Thurman-Keup, R.; Scarpine, V.; /Fermilab et al.
Partner: UNT Libraries Government Documents Department

Energy Measurement in a Plasma Wakefield Accelerator

Description: In the E-167 plasma wakefield acceleration experiment, electrons with an initial energy of 42GeV are accelerated in a meter-scale lithium plasma. Particles are leaving plasma with a large energy spread. To determine the spectrum of the accelerated particles, a two-plane spectrometer has been set up.
Date: July 6, 2007
Creator: Ischebeck, R
Partner: UNT Libraries Government Documents Department

An Ultra-High Gradient Cherenkov Wakefield Acceleration Experiment at SLAC FFTB

Description: The creation of ultra-high current, ultra-short pulse beams Q=3 nC, {sigma}{sub z} = 20{micro}m at the SLAC FFTB has opened the way for very high gradient plasma wakefield acceleration experiments. We study here the use of these beams in a proposed Cherenkov wakefield experiment, where one may excite electromagnetic wakes in a simple dielectric tube with inner diameter of few 100 microns that exceed the GV/m level. We discuss the scaling of the fields with design geometric design parameters, and choice of dielectric. We also examine measurable aspects of the experiment, such as the total coherent Cerenkov radiation energy one may collect, and the expected aspects of dielectric breakdown at high fields.
Date: August 2, 2005
Creator: Rosenzweig, J.B.; Hoover, S.; Hogan, M.J.; Muggli, P.; Thompson, M.; Travish, G. et al.
Partner: UNT Libraries Government Documents Department

Limiting Effects in the Transverse-to-Longitudinal Emittance Exchange Technique for Low Energy Relativistic Electron Beams

Description: Transverse to longitudinal phase space manipulation hold great promises, e.g., as a potential technique for repartitioning the emittances of a beam. A proof-of-principle experiment to demonstrate the exchange of a low longitudinal emittance with a larger transverse emittance is in preparation at the Argonne Wakefield Accelerator using a {approx}12 MeV electron beam. In this paper we explore the limiting effects of this phase space manipulation method including high order and collective effects. A realistic start-to-end simulation of the planned proof-of-principle experiment including sensitivity studies is also presented.
Date: May 1, 2009
Creator: Rihaoui, M. M.; Piot, P.; Power, J. G. & Gai, W.
Partner: UNT Libraries Government Documents Department

Modeling laser wakefield accelerators in a Lorentz boosted frame

Description: Modeling of laser-plasma wakefield accelerators in an optimal frame of reference is shown to produce orders of magnitude speed-up of calculations from first principles. Obtaining these speedups requires mitigation of a high-frequency instability that otherwise limits effectiveness in addition to solutions for handling data input and output in a relativistically boosted frame of reference. The observed high-frequency instability is mitigated using methods including an electromagnetic solver with tunable coefficients, its extension to accomodate Perfectly Matched Layers and Friedman's damping algorithms, as well as an efficient large bandwidth digital filter. It is shown that choosing the frame of the wake as the frame of reference allows for higher levels of filtering and damping than is possible in other frames for the same accuracy. Detailed testing also revealed serendipitously the existence of a singular time step at which the instability level is minimized, independently of numerical dispersion, thus indicating that the observed instability may not be due primarily to Numerical Cerenkov as has been conjectured. The techniques developed for Cerenkov mitigation prove nonetheless to be very efficient at controlling the instability. Using these techniques, agreement at the percentage level is demonstrated between simulations using different frames of reference, with speedups reaching two orders of magnitude for a 0.1 GeV class stages. The method then allows direct and efficient full-scale modeling of deeply depleted laser-plasma stages of 10 GeV-1 TeV for the first time, verifying the scaling of plasma accelerators to very high energies. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively.
Date: June 15, 2010
Creator: Vay, J.-L.; Geddes, C.G.R.; Cormier-Michel, E. & Grotec, D. P.
Partner: UNT Libraries Government Documents Department

Wakefield acceleration in structures.

Description: Wakefield acceleration in dielectric loaded structures is discussed in this paper. We present a description of the dielectric wakefield accelerator concept, comparing some features of the collinear and the two beam accelerator configurations. The Argonne Wakefield Accelerator Facility (AWA) is discussed in detail, including major upgrades that are presently taking place. The basic features and capabilities of the facility are presented, and the dielectric wakefield acceleration results are briefly summarized. Possible variants of the two beam accelerator configuration are discussed, and work on planar dielectric structures in various institutions is presented. We conclude this report mentioning prospective achievements of dielectric wakefield accelerating structures.
Date: September 17, 2002
Creator: Conde, M. E.
Partner: UNT Libraries Government Documents Department

Electron acceleration in preformed plasma channels with terawatt CO{sub 2} laser

Description: Extended cylindrical plasma channels produced under gas breakdown by axicon-focused laser beams may be used as optical waveguides in laser-driven electron accelerators. Plasma channeling of the laser beams will help to maintain a high acceleration gradient over many Rayleigh lengths. In addition, the rarefied gas density channel produced after the optical gas breakdown, and followed by a plasma column expansion, reduces multiple scattering of the electron beam. A high-power picosecond C0{sub 2}laser operational at the ATF and being further upgraded to the 1 TW level is considered as the source for a plasma channel formation and as the laser accelerator driver. We show how various laser accelerator schemes including beat wave, wake field, and Inverse Cherenkov accelerator benefit from using a channeled short-pulse C0{sub 2}laser as a driver.
Date: February 1, 1995
Creator: Pogorelsky, I.V.
Partner: UNT Libraries Government Documents Department

The method of boundary perturbation, and its application to wakefield calculations

Description: The boundary perturbation method, suggested by Zhang and (independently) by Chatard-Moulin, Cooper, and their colleagues, is employed to the wakefield calculations for geometrical discontinuities in accelerators. Results are compared with that obtained from the mesh calculations using TBCI. When the perturbation is small and the geometry is suitable for TBCI, agreement is good. Discrepancies observed in other cases are also discussed.
Date: December 31, 1990
Creator: Chou, W.
Partner: UNT Libraries Government Documents Department

Summary report: working group 2 on 'Plasma Based AccelerationConcepts'

Description: A summary of the talks, papers and discussion sessions presented in the Working Group on Plasma Based Acceleration Concepts is given within the context of the progress towards a 1 GeV laser driven accelerator module. The topics covered within the Working Group were self-modulated laser wakefield acceleration, standard laser wakefield acceleration, plasma beatwave acceleration, laser guiding and wake excitation in plasma channels, plasma wakefield acceleration, plasma lenses and optical injection techniques for laser wakefield accelerators. An overview will be given of the present status of experimental and theoretical progress as well as an outlook towards the future physics and technological challenges for the development of an optimized accelerator module.
Date: September 1, 1998
Creator: Esarey, E. & Leemans, Wim
Partner: UNT Libraries Government Documents Department

The Argonne Wakefield Accelerator: Upgrade scenarios and future experiments

Description: The Argonne Wakefield Accelerator is presently operational and nearing completion of its initial dielectric structure- and plasma-based experimental program. In this paper a number of possible future improvements and directions for the AWA are discussed including photocathode source upgrades, laser pulse and beam shaping options, multiple drive bunch generation, and novel wakefield device measurements. Plans for a 1 GeV demonstration wakefield accelerator will be presented.
Date: October 1, 1997
Creator: Gai, W.; Conde, M.; Konecny, R.; Li, X.; Power, J.; Schoessow, P. et al.
Partner: UNT Libraries Government Documents Department