Author: Fedurin, M.G.
Paper Title Page
MOPPP012 Experimental Observation of Energy Modulation in Electron Beams Passing through Terahertz Dielectric Wakefield Structures 595
 
  • S.P. Antipov, C.-J. Jing, A. Kanareykin, P. Schoessow
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • M.G. Fedurin, K. Kusche, V. Yakimenko
    BNL, Upton, Long Island, New York, USA
  • W. Gai, A. Zholents
    ANL, Argonne, USA
  • B.C. Jiang
    SINAP, Shanghai, People's Republic of China
 
  Funding: DOE SBIR.
We report observation of a strong wakefield induced energy modulation in an energy-chirped electron bunch passing through a terahertz dielectric-lined waveguide. This modulation can be effectively converted into a spatial modulation by means of a chicane, forming micro-bunches (density modulation) with a periodicity of 0.5 - 1 picosecond, hence capable of driving coherent THz radiation. The experimental results agree well with theoretical predictions.
 
 
MOPPP013 Passive Momentum Spread Compensation by a “Wakefield Silencer” 598
 
  • S.P. Antipov, C.-J. Jing, A. Kanareykin, P. Schoessow
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • M.G. Fedurin, K. Kusche, V. Yakimenko
    BNL, Upton, Long Island, New York, USA
  • W. Gai, A. Zholents
    ANL, Argonne, USA
 
  Funding: DOE SBIR.
We report an observation of de-chirping of a linearly chirped (in energy) electron bunch by its passage through a 5 cm long dielectric loaded waveguide structure. The experiment was conducted at the ATF facility at BNL according to a concept dubbed a wakefield silencer originally developed at the ANL AATF*, which involves defining the electron bunch peak current distribution and selecting the optimal waveguide structure suitable for chirp cancellation using self-induced wakefields of the electron bunch. Our experiment has been carried out with a 247 micron triangular beam with a 200 keV energy spread, which was reduced by a factor of three to approximately 70 keV by passing it through a 0.95 THz dielectric-lined structure. Theoretical analysis supports the experimental results. Further exploration and applications of this technique will be discussed as well.
* M. Rosing, J. Simpson, Argonne Wakefield Accelerator Note, WF -144 (1990).
 
 
WEPPP008 Vacuum Laser Acceleration Experiment Perspective at Brookhaven National Lab-Accelerator Test Facility 2735
 
  • X.P. Ding, D.B. Cline, L.S. Shao
    UCLA, Los Angeles, California, USA
  • M.G. Fedurin, K. Kusche, I. Pogorelsky, V. Yakimenko
    BNL, Upton, Long Island, New York, USA
  • Y.K. Ho, Q. Kong
    Fudan University, Shanghai, People's Republic of China
  • J.J. Xu
    Shanghai Institute of Optics and Fine Mechanics, Shanghai, People's Republic of China
 
  Funding: Supported by the DOE under award number DE-FG02-92ER40695 (UCLA)
This paper presents the pre-experiment plan and prediction of the first stage of Vacuum Laser Acceleration (VLA) collaborating by UCLA, Fudan University and ATF-BNL. This first stage experiment is a Proof-of-Principle to support our previously posted novel VLA theory. Simulations show that based on ATF’s current experimental conditions, the electron beam with initial energy of 15MeV can get net energy gain from intense CO2 laser beam. The difference of electron beam energy spread is observable by ATF beam line diagnostics system. Further this energy spread expansion effect increases along with the laser intensity increasing. The proposal has been approved by ATF committee and experiment will be the next project.
 
 
WEPPP015 Generation and Characterization of 5-micron Electron Beam for Probing Optical Scale Structures 2753
 
  • M.G. Fedurin, M. Babzien, V. Yakimenko
    BNL, Upton, Long Island, New York, USA
  • B.A. Allen
    USC, Los Angeles, California, USA
  • P. Muggli
    MPI, Muenchen, Germany
  • A.Y. Murokh
    RadiaBeam, Santa Monica, USA
 
  In recent years advanced acceleration technologies have progress toward combination of electron beam, laser and optical scale dielectric structures. In present paper described generation of the electron beam probe with parameters satisfied to perform test of such optical structures.  
 
WEPPP037 Experimental Study of Self Modulation Instability of ATF Electron Beam 2807
 
  • Y. Fang
    USC, Los Angeles, California, USA
  • M. Babzien, M.G. Fedurin, K. Kusche, R. Malone, V. Yakimenko
    BNL, Upton, Long Island, New York, USA
  • W.B. Mori
    UCLA, Los Angeles, California, USA
  • P. Muggli
    MPI, Muenchen, Germany
  • L.O. Silva, J. Vieira
    Instituto Superior Tecnico, Lisbon, Portugal
 
  Funding: US. Department of Energy.
We demonstrate experimentally for the first time the self-modulation of a relativistic electron bunch in a plasma. This demonstration serves as a proof-of-principle test for the mechanisms of transverse self-modulation of particle bunches in plasmas. It indicates the possibility of using long electron or proton bunches as drivers for plasma based accelerators. The long (~5ps) bunch available at BNL-ATF is used in this experiment and in the particle-in-cell OSIRIS. We use the 2D version for cylindrically symmetric geometries. The energy of the beam particles is measured after the plasma exit in the experiment. The obvious energy gain and loss by electrons indicates the excitation of longitudinal wakefields, and hence of transverse focusing fields. Both simulations and experiments show that the electron beamlets are formed at the scale of the plasma wavelength, and the number of beamlets changes as the plasma density is varied. We also measured the variation in beam transverse size downstream from the plasma as well as the variations in coherent transition radiation energy to demonstrate the effect of transverse self–modulation.
 
 
WEPPP042 Experimental Demonstration of Wakefield Effects in a 250 GHz Planar Diamond Accelerating Structure 2816
 
  • S.P. Antipov, J.E. Butler, C.-J. Jing, A. Kanareykin, P. Schoessow, S.S. Zuo
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • M.G. Fedurin, K. Kusche, V. Yakimenko
    BNL, Upton, Long Island, New York, USA
  • W. Gai
    ANL, Argonne, USA
 
  Funding: DOE SBIR
We have directly measured the mm-wave wake fields induced by subpicosecond, intense relativistic electron bunches in a diamond loaded accelerating structure via the dielectric wake-field acceleration mechanism. Fields produced by a first, drive, beam were used to accelerate a second, witness, electron bunch which followed the driving bunch at an adjustable distance. The energy gain of the witness bunch as a function of its separation from the drive bunch is a direct measurement of the wake potential. We also present wakefield mapping results for THz quartz structures. In this case decelerating wake inside the bunch is inferred from the drive beam energy modulation.
 
 
WEPPP051 Excitation of Plasma Wakefields with Designer Bunch Trains 2828
 
  • P. Muggli
    MPI, Muenchen, Germany
  • B.A. Allen, Y. Fang
    USC, Los Angeles, California, USA
  • M. Babzien, M.G. Fedurin, K. Kusche, R. Malone, C. Swinson, V. Yakimenko
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by US Department of Energy.
Plasma can sustain multi-GV/m longitudinal electric fields that can be used for particle acceleration. In the plasma wakefield accelerator, or PWFA, the wakefields are driven by a single or a train of electron bunches with length comparable to the plasma wavelength. A train of bunches resonantly driving the wakefields can lead to energy gain by trailing particles many times the energy of the incoming drive train particles (large transformer ratio). In proof-of-principle experiments at the Brookhaven National Laboratory Accelerator Test Facility, we demonstrate by varying the plasma density over four orders of magnitude, and therefore the accelerator frequency over two orders of magnitude (~100GHz to a few THz), that trains with ~ps period resonantly drive wakefields in ~1016/cc density plasmas. We also demonstrate energy gain by a trailing witness electron bunch that follows the drive train with a variable delay. Detailed experimental results will be presented.
 
 
WEPPR089 Experimental Progress: Current Filamentation Instability Study 3141
 
  • B.A. Allen, P. Muggli
    USC, Los Angeles, California, USA
  • M. Babzien, M.G. Fedurin, K. Kusche, V. Yakimenko
    BNL, Upton, Long Island, New York, USA
  • C. Huang
    LANL, Los Alamos, New Mexico, USA
  • J.L. Martins, L.O. Silva
    IPFN, Lisbon, Portugal
  • W.B. Mori
    UCLA, Los Angeles, California, USA
 
  Funding: Work supported by: National Science Foundation and US Department of Energy.
Current Filamentation Instability, CFI, is of central importance for the propagation of relativistic electron beams in plasmas. CFI has potential relevance to astrophysics, magnetic field and radiation generation in the afterglow of gamma ray bursts, and inertial confinement fusion, energy transport in the fast-igniter concept. An experimental study of this instability is underway at the Accelerator Test Facility, ATF, at Brookhaven National Laboratory with the 60MeV electron beam and centimeter length capillary discharge plasma. The experimental program includes the systematic study and characterization of the instability as a function of beam (charge, transverse and longitudinal profile) and plasma (plasma density) parameters. Specifically, the transverse beam profile is measured directly at the plasma exit using optical transition radiation from a thin gold-coated silicon window. Experimental results show the reduction of the beam transverse size and the appearance of multiple (1-4) filaments and are a function of the plasma density. We will present simulation and experimental results, provide discussion of these results and outline next steps in the experiment.
 
 
THEPPB008 Inverse Compton Scattering Experiment in a Bunch Train Regime Using Nonlinear Optical Cavity 3245
 
  • A.Y. Murokh, R.B. Agustsson, S. Boucher, P. Frigola, T. Hodgetts, A.G. Ovodenko, M. Ruelas, R. Tikhoplav
    RadiaBeam, Santa Monica, USA
  • M. Babzien, M.G. Fedurin, T.V. Shaftan, V. Yakimenko
    BNL, Upton, Long Island, New York, USA
  • I. Jovanovic
    Penn State University, University Park, Pennsylvania, USA
 
  Inverse Compton Scattering (ICS) is a promising approach towards achieving high intensity, directional beams of quasi-monochromatic gammas, which could offer unique capabilities in research, medical and security applications. Practicality implementation of ICS sources, however, depends on the ability to achieve high peak brightness (~0.1-1.0 ICS photons per interacting electron), while increasing electron-laser beam interaction rate to about 10,000 cps. We discuss the results of the initial experimental work at the Accelerator Test Facility (ATF) at BNL to demonstrate ICS interaction in a pulse-train regime, using a novel laser recirculation scheme termed Recirculation Injection by Nonlinear Gating (RING). Initial experimental results and outlook are presented.