Author: Mann, J.I.
Paper Title Page
WEPAB056 Advanced Photoinjector Development at the UCLA SAMURAI Laboratory 2728
 
  • A. Fukasawa, G. Andonian, O. Camacho, C.E. Hansel, G.E. Lawler, W.J. Lynn, N. Majernik, P. Manwani, B. Naranjo, J.B. Rosenzweig, Y. Sakai, O. Williams
    UCLA, Los Angeles, California, USA
  • Z. Li, R. Robles, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  • J.I. Mann
    PBPL, Los Angeles, USA
  • M. Yadav
    The University of Liverpool, Liverpool, United Kingdom
 
  Funding: This work was supported by the US Department of Energy under the contract No. DE-SC0017648, DE-SC0009914, and DE-SC0020409, and by National Science Foundation Grant No. PHY-1549132
UCLA has recently constructed SAMURAI, a new radiation bunker and laser infrastructure for advanced accelerator research. In its first phase, we will build a 30 MeV photoinjector with an S-band hybrid gun. The beam dynamics simulation for this beamline showed the generation of the beam with the emittance 2.4 um and the peak current 270 A. FIR-FEL experiments are planned in this beamline. The saturation peak power was expected at 170 MW.
 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB056  
About • paper received ※ 28 May 2021       paper accepted ※ 01 July 2021       issue date ※ 11 August 2021  
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THPAB344 Magneto-Optical Trap Cathode for High Brightness Applications 4466
 
  • V.S. Yu, C.E. Hansel, G.E. Lawler, M. Mills, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • J.I. Mann
    PBPL, Los Angeles, USA
 
  Funding: This work was performed with support of the US Department of Energy under Contract No. DE-SC0020409 and the National Science Foundation under Grant No. PHY-1549132
Electron bunches extracted from magneto-optical traps (MOTs) via femtosecond photo-ionization and electrostatic acceleration can have significantly lower transverse emittance than emissions from traditional metal cathodes. Such MOT cathodes, however, have two drawbacks: the need for multiple trapping lasers and the limit to ~MV/m fields. Designs exist for MOTs which only require one trapping laser. Our RF simulations in High-Frequency Structure Simulator (HFSS) indicate that the cone MOT is the only one compatible with high gradient RF cavities. We present the combination of the two, an RF cavity with a cone-MOT as part of its geometry. It only requires one trapping laser and can use much higher fields. The geometry of the chamber is compatible with a wide range of MOT species, which allows the search for one which is compatible with copper cavities.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB344  
About • paper received ※ 19 May 2021       paper accepted ※ 29 July 2021       issue date ※ 12 August 2021  
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WEPAB097 Initial Nanoblade-Enhanced Laser-Induced Cathode Emission Measurements 2814
 
  • G.E. Lawler, J.I. Mann, J.B. Rosenzweig, V.S. Yu
    UCLA, Los Angeles, California, USA
  • R.J. Roussel
    University of Chicago, Chicago, Illinois, USA
 
  Funding: This work was supported by the Center for Bright Beams, National Science Foundation Grant No. PHY-1549132 and DOE HEP Grant DE-SC0009914
Nanostructured photocathodes offer a unique functionality not possible in traditional photocathodes, increasing beam brightness by reducing the effective emission area. Inspired by field emitter tips, we examine a possible extension for higher current operation, an extended nanoblade capable of producing asymmetric emittance electron beams. A full understanding of emission is necessary to establish the effectiveness of nanoblades as usable cathode for electron accelerators. Utilizing wet etching of silicon wafers, we arrive at a robust sample capable of dissipating incident laser fields in excess of 20 GV/m without permanent damage. Initial predictions and experiments from the nanotip case predict energies up to the keV scale from electron rescattering and fine features on the order of the photon quantum. We will present initial electron data from 800 nm Ti:S laser illumination and measurements of a focused 1 keV beam.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB097  
About • paper received ※ 19 May 2021       paper accepted ※ 24 June 2021       issue date ※ 15 August 2021  
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WEPAB147 Simulations of Nanoblade-Enhanced Laser-Induced Cathode Emissions and Analyses of Yield, MTE, and Brightness 2957
 
  • J.I. Mann, G.E. Lawler, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • T. Arias, J.K. Nangoi
    Cornell University, Ithaca, New York, USA
 
  Funding: This work was supported by the Center for Bright Beams, National Science Foundation Grant No. PHY-1549132 and DOE HEP Grant DE-SC0009914.
Laser-induced field emission of electrons from metallic nanotips has been well studied. Unfortunately, nanotips suffer low damage thresholds with enhanced fields around 10 GV/m. The nanoblade, akin to a nanotip extruded in one lateral dimension, may reach upwards of 40 GV/m due to its robust thermomechanical properties. This increased surface field promises brighter electron emissions. We perform simulations of strong-field emissions from metallic nanoblades via the 1-D time-dependent Schr\"odinger equation with effective Jellium and nonlinear collective image charge potentials, including the strong field gradients induced by the nanostructure. We measure spectra and yields and compare to recent experiments. Potential analytical forms of image potential limited yield for a spectrally rich emission are presented. Calculations of mean transverse energy are provided as well as a prospective method of mitigation with the goal of increasing brightness.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB147  
About • paper received ※ 19 May 2021       paper accepted ※ 06 July 2021       issue date ※ 01 September 2021  
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THPAB071 Physics Goals of DWA Experiments at FACET-II 3922
 
  • J.B. Rosenzweig, H.S. Ancelin, G. Andonian, A. Fukasawa, C.E. Hansel, G.E. Lawler, W.J. Lynn, N. Majernik, J.I. Mann, P. Manwani, Y. Sakai, O. Williams, M. Yadav
    UCLA, Los Angeles, California, USA
  • S.V. Baryshev
    Michigan State University, East Lansing, Michigan, USA
  • S. Baturin
    Northern Illinois University, DeKalb, Illinois, USA
  • M.J. Hogan, B.D. O’Shea, D.W. Storey, V. Yakimenko
    SLAC, Menlo Park, California, USA
 
  Funding: This work supported by DOE HEP Grant DE-SC0009914,
The dielectric wakefield acceleration (DWA) program at FACET produced a multitude of new physics results that range from GeV/m acceleration to the discovery of high field-induced conductivity in THz waves, and beyond, to a demonstration of positron-driven wakes. Here we review the rich program now developing in the DWA experiments at FACET-II. With increases in beam quality, a key feature of this program is extended interaction lengths, near 0.5 m, permitting GeV-class acceleration. Detailed physics studies in this context include beam breakup and its control through the exploitation of DWA structure symmetry. The next step in understanding DWA limits requires the exploration of new materials with low loss tangent, large bandgap, and improved thermal characteristics. Advanced structures with photonic features for mode confinement and exclusion of the field from the dielectric, as well as quasi-optical handling of coherent Cerenkov signals is discussed. Use of DWA for laser-based injection and advanced temporal diagnostics is examined.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB071  
About • paper received ※ 25 May 2021       paper accepted ※ 28 July 2021       issue date ※ 22 August 2021  
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