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A Vlasov Solver for Longitudinal Dynamics in Beam Delivery Systems for X-Ray FELs

Description: Direct numerical methods for solving the Vlasov equationoffer some advantages over macroparticle simulations, as they do notsuffer from the consequences of the statistical fluctuations inherent inusing a number of macroparticles smaller than thebunch population.Unfortunately these methods are more time-consuming and generallyconsidered impractical in a full 6D phase space. However, in alower-dimension phase space they may become attractive if the beamdynamics is sensitive to the presence of sma… more
Date: May 9, 2007
Creator: Venturini, Marco; Warnock, Robert & Zholents, Alexander
Partner: UNT Libraries Government Documents Department
open access

Feasibility analysis for attosecond X-ray pulses at FERMI@ELETTRA free electron laser

Description: We present preliminary analysis for the feasibility of the attosecond x-ray pulses at a proposed FERMI@ELETTRA free electron laser (FEL) [1]. In part 1 we restrict ourselves to minimal modifications to the proposed FEL and consider a scheme for attosecond x-ray production which can be qualified as a small add-on to a primary facility. We demonstrate that at 5-nm wavelength our scheme is capable for production of pulses with an approximate duration of 100 attoseconds at approximately 2 MW peak p… more
Date: September 1, 2004
Creator: Zholents, Alexander
Partner: UNT Libraries Government Documents Department
open access

Methods of Attosecond X-Ray Pulse Generation

Description: We review several proposals for generation of solitary attosecond pulses using two types of free electron lasers which are envisioned as future light sources for studies of ultra-fast dynamics using soft and hard x-rays.
Date: May 8, 2005
Creator: Zholents, Alexander
Partner: UNT Libraries Government Documents Department
open access

Proposal for an Enhanced Self-Amplified Spontaneous Emission X-ray Free Electron Laser

Description: We describe a technique by which an energy modulation of electrons via interaction with a laser pulse in a wiggler magnet is used for a significant increase of the electron peak current prior to entering a long SASE FEL undulator. This results in a reduction of the gain length for the SASE process and a modification of the structure of the output x-ray radiation. It also temporally links the output x-ray pulse to the initial laser pulse, thus providing an opportunity for accurate synchronizatio… more
Date: February 1, 2004
Creator: Zholents, Alexander
Partner: UNT Libraries Government Documents Department
open access

GENERATION OF SUBPICOSECOND X-RAY PULSES IN STORAGE RINGS

Description: Supicosecond x-ray pulses are routinely produced at ALS,BESSY and SLS with slicing technique and used in pump-probe experimentswith controlled delay between laser pump pulses and x-ray probe pulses.New development aiming for a production of a subpicosecond x-ray pulsesusing rf orbit deflection technique is under way at APS. Both techniqueswill be reviewed here.
Date: June 19, 2007
Creator: Zholents, Alexander A.
Partner: UNT Libraries Government Documents Department
open access

Beam break up analysis for the Berkeley Recirculating Linac Light Source

Description: We describe here a study of a single bunch Beam Break Up (BBU) instability for a proposed Berkeley fast x-ray facility based on a recirculating linac [1]. The recirculating linac employs a 600 MeV superconducting RF linear accelerator and the electron beam energy of {approx} 2.5 GeV is reached over four beam passes through the linac. A 120 MeV superconducting RF linear accelerator is used as an injector to the recirculating linac. The machine parameters are listed in Appendix A. The equation de… more
Date: January 20, 2002
Creator: De Santis, Stefano & Zholents, Alexander A.
Partner: UNT Libraries Government Documents Department
open access

Towards attosecond X-ray pulses from the FEL

Description: The ability to study ultrafast phenomena has been recently advanced by the demonstrated production and measurement of a single, 650-attosecond (10{sup 18} sec), VUV x-ray pulse[1] and, latter, a 250-attosecond pulse[2]. The next frontier is a production of the x-ray pulses with shorter wavelengths and in a broader spectral range. Several techniques for a generation of an isolated, attosecond duration, short-wavelength x-ray pulse based upon the ponderomotive laser acceleration [3], SASE and har… more
Date: July 1, 2004
Creator: Zholents, Alexander A. & Fawley, William M.
Partner: UNT Libraries Government Documents Department
open access

Beam break up analysis for the Berkeley femtosource

Description: We present a study of the single-bunch beam break up (BBU) instability for a proposed x-ray facility, based on a recirculating linac, to be built in Berkeley. The effects of injection errors, both position and angle, and of misalignments in the linac are investigated. We propose possible methods for limiting the consequent emittance increase.
Date: May 30, 2002
Creator: De Santis, Stefano & Zholents, Alexander A.
Partner: UNT Libraries Government Documents Department
open access

Simulations of the microbunching instability in beam deliverysystems for free electron lasers

Description: In this paper, we examine the growth of the microbunchinginstability in the electron beam delivery system of a free electron laser(FEL). We present the results of two sets of simulations, one conductedusing a direct Vlasov solver, the other using a particle-in-cell codeImpact-Z with the number of simulation macroparticles ranging up to 100million. Discussion is focused on the details of longitudinal dynamicsand on numerical values of uncorrelated (slice) energy spread atdifferent points in the … more
Date: June 29, 2007
Creator: Pogorelov, Ilya; Qiang, Ji; Ryne, Rob; Venturini, Marco; Zholents, Alexander & Warnock, Robert
Partner: UNT Libraries Government Documents Department
open access

Modeling Microbunching from Shot Noise Using Vlasov Solvers

Description: Unlike macroparticle simulations, which are sensitive to unphysical statistical fluctuations when the number of macroparticles is smaller than the bunch population, direct methods for solving the Vlasov equation are free from sampling noise and are ideally suited for studying microbunching instabilities evolving from shot noise. We review a 2D (longitudinal dynamics) Vlasov solver we have recently developed to study the microbunching instability in the beam delivery systems for x-ray FELs and p… more
Date: May 1, 2008
Creator: Venturini, Marco; Venturini, Marco & Zholents, Alexander
Partner: UNT Libraries Government Documents Department
open access

Obtaining two attosecond pulses pulses for x-ray stimulated Raman spectroscopy

Description: Attosecond x-ray pulses are an indispensable tool for the study of electronic and structural changes in molecules undergoing chemical reactions. They have a wide bandwidth comparable to the energy bands of valence electronic states and, therefore, are well suited for making and probing multiple valence electronic excitations using core electron transitions. Here we propose a method of creating a sequence of two attosecond soft x-ray pulses in a free electron laser by optical manipulation of ele… more
Date: June 23, 2009
Creator: Zholents, Alexander & Penn, G.
Partner: UNT Libraries Government Documents Department
open access

Development of a 2D Vlasov Solver for Single-Pass Systems

Description: Direct numerical methods for solving the Vlasov equationoffer some advantages over macroparticle simulations, as they do notsuffer from the numerical noise inherent in using a number ofmacroparticles smaller than the bunch population. Unfortunately thesemethods are more time-consuming and generally considered impractical in afull 6D phase space. However, in a lower-dimension phase space they maybecome attractive if the beam dynamics is sensitive to the presence ofsmall charge-density fluctuatio… more
Date: July 31, 2006
Creator: Venturini, Marco; Warnock, Robert & Zholents, Alexander
Partner: UNT Libraries Government Documents Department
open access

Investigation of Beam Instability Under the Effects of Long-Range Transverse Wake Fields in the Berkeley Future Light Source

Description: An ultra-relativistic charged particle bunch moving through a resonator cavity leaves behind a wake field that will affect subsequent bunches (if the bunch is not ultra-relativistic, the wake field will not be exclusively behind it). If the initial bunch enters the cavity off-axis, it will produce a transverse wake field that can then kick later bunches off the axis. Thus, even bunches that were initially traveling on axis could be displaced and, in turn, produce their own transverse wake field… more
Date: August 31, 2008
Creator: Kur, Eugene & Zholents, Alexander A.
Partner: UNT Libraries Government Documents Department
open access

Halo particle confinement in the VLHC using optical stochastic cooling

Description: Beam halo particles following the extreme trajectories near the physical aperture limit radiate Smith-Purcell radiation when moving over a diffraction grating. This grating can be used as a pick-up and a kicker for optical stochastic cooling of the halo particles. In this application cooling would have the effect of slowing down the halo particle diffusion onto the aperture. Cooling efficiency would quickly diminish with the distance from the aperture and would only affect the halo particles. A… more
Date: June 1, 2000
Creator: Zholents, Alexander; Barletta, W.; Chattopadhyay, S. & Zolotorev, M.
Partner: UNT Libraries Government Documents Department
open access

Beam energy spread in FERMI@elettra gun and linac induced by intrabeam scattering

Description: Intrabeam scattering (IBS) of electrons in the pre-cathode area in the electron guns know in the literature as Boersh effect is responsible for a growth of the electron beam energy spread there. Albeit most visible within the electron gun where the electron beam density is large and the energy spread is small, the IBS acts all along the entire electron beam pass through the Linac. In this report we calculate the energy spread induced by IBS in the FERMI@elettra electron gun.
Date: July 11, 2008
Creator: Zholents, Alexander A.; Zolotorev, Max S. & Penco, Giuseppe
Partner: UNT Libraries Government Documents Department
open access

Re-circulating linac vacuum system

Description: The vacuum system for a proposed 2.5 GeV, 10{Mu}A recirculating linac synchrotron light source [1] is readily achievable with conventional vacuum hardware and established fabrication processes. Some of the difficult technical challenges associated with synchrotron light source storage rings are sidestepped by the relatively low beam current and short beam lifetime requirements of a re-circulating linac. This minimal lifetime requirement leads directly to relatively high limits on the background… more
Date: May 9, 2003
Creator: Wells, Russell P.; Corlett, John N. & Zholents, Alexander A.
Partner: UNT Libraries Government Documents Department
open access

An injector for the proposed Berkeley Ultrafast X-Ray Light Source

Description: Berkeley Lab has proposed to build a recirculating linac based X-ray source for ultra-fast dynamic studies [1]. This machine requires a flat electron beam with a small vertical emittance and large x/y emittance ratio to allow for compression of spontaneous undulator emission of soft and hard x-ray pulses, and a low-emittance, round electron beam for coherent emission of soft x-rays via the FEL process based on cascaded harmonic generation [2]. We propose an injector system consisting of two hig… more
Date: May 19, 2003
Creator: Lidia, Steven; Corlett, John; Pusina, Jan; Staples, John & Zholents, Alexander
Partner: UNT Libraries Government Documents Department
open access

Intense attosecond radiation from an X-ray FEL - extended version

Description: We propose the use of a ultra-relativistic electron beam interacting with a few-cycle, intense laser pulse and an intense pulse of the coherent x-rays to produce a multi-MW intensity, x-ray pulses {approx}100 attoseconds in duration. Due to a naturally-occurring frequency chirp, these pulses can be further temporally compressed.
Date: December 1, 2003
Creator: Zholents, Alexander A. & Fawley, William M.
Partner: UNT Libraries Government Documents Department
open access

Generation of attosecond electron bunches

Description: Ultra-fast science is an important new research frontier that is driving the development of novel sources for generation of extremely short x-ray and electron pulses. Recent advances in femtosecond lasers have stimulated development of femtosecond x-ray sources that allow the study of matter at the time scale shorter than period of oscillations of atoms in molecules, {approx} 100 fs. The next breakthrough would be a source of electron pulses comparable with atomic periods {omega}{sup -1} {appro… more
Date: June 18, 2001
Creator: Zholents, Alexander A.; Zolotorev, Max S. & Wan, Weishi
Partner: UNT Libraries Government Documents Department
open access

LINAC DESIGN FOR AN ARRAY OF SOFT X-RAY FREE ELECTRON LASERS

Description: 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 lattice, bunch compression, collimation, and the beam switch yard are discussed. Particular attention is given to collective effects. A demanding goal is to preserve both a low beam slice emi… more
Date: September 22, 2008
Creator: Zholents, Alexander A.; Kur, E.; Penn, G.; Qiang, Ji; Venturini, M. & Wells, R. P.
Partner: UNT Libraries Government Documents Department
open access

Tailored terahertz pulses from a laser-modulated electronbeam

Description: Interaction of an electron beam with a femtosecond laserpulseco-propagating through a wiggler modulates the electronenergieswithin a short slice of the electron bunch comparable with the durationof the laser pulse (Figure 1). Propagating around an electron storagering, this bunch develops a longitudinal density perturbation due to thedispersion of electron trajectories. Figure 1 shows how this createsfemtosecond electron bunch wings which are used for femtosecond x-raylight. In addition, this d… more
Date: July 19, 2005
Creator: Martin, Michael C.; Byrd, John; Hao, Zhao; Robin, David; Sannibale,Fernando; Schoenlein, Robert W. et al.
Partner: UNT Libraries Government Documents Department
open access

Design and Commissioning Plan for a Laser Heater for FERMI@elettra

Description: The purpose of a laser heater is to increase the electron beam uncorrelated energy spread as a way to control and ideally suppress the microbunching instability in the linac drive for x-rays FELs. We review the motivations for equipping FERMI with a laser heater and provide a specification for the basics parameters as well as a description of a practical layout including desired diagnostics provisions for both the electron and laser beams. We also outline some useful operational guidelines for … more
Date: October 25, 2008
Creator: Zholents, Alexander A.; Qiang, J.; Venturini, M.; Wells,, R.; Wilcox, R.; Di Mitri, S. et al.
Partner: UNT Libraries Government Documents Department
open access

The FERMI @ Elettra Technical Optimization Study: PreliminaryParameter Set and Initial Studies

Description: The goal of the FERMI {at} Elettra Technical Optimization Study is to produce a machine design and layout consistent with user needs for radiation in the approximate ranges 100 nm to 40 nm, and 40 nm to 10 nm, using seeded FEL's. The Study will involve collaboration between Italian and US physicists and engineers, and will form the basis for the engineering design and the cost estimation.
Date: August 1, 2005
Creator: Byrd, John; Corlett, John; Doolittle, Larry; Fawley, William; Lidia, Steven; Penn, Gregory et al.
Partner: UNT Libraries Government Documents Department
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