Author: Zhang, H.D.
Paper Title Page
MOPMA005 Non-invasive Beam Profile Monitoring 537
 
  • C.P. Welsch, T. Cybulski, A. Jeff, V. Tzoganis, H.D. Zhang
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • T. Cybulski, A. Jeff, V. Tzoganis, C.P. Welsch, H.D. Zhang
    The University of Liverpool, Liverpool, United Kingdom
  • A. Jeff
    CERN, Geneva, Switzerland
  • V. Tzoganis
    RIKEN, Saitama, Japan
 
  Funding: Work supported by the Helmholtz Association under contract VH-NG-328, the EU under contracts 215080 and 289485, as well as the STFC Cockcroft core grant No. ST/G008248/1.
State-of-the-art high energy and high intensity accelerators require new approaches to transverse beam profile monitoring as many established techniques will no longer work due to the high power stored in the beam. In addition, many accelerator applications such as ion beam cancer therapy or material irradiation would benefit significantly from the availability of non-invasive beam profile monitors. Research in the QUASAR Group has focused on this area over the past 5 years. Two different approaches were successfully developed: Firstly, a supersonic gas jet-based monitor was designed and commissioned. It enables the detection of the 2-dimensional transverse beam profile of essentially any charged particle beam with negligible disturbance of the primary beam and accelerator vacuum. Secondly, a monitor based on the Silicon strip VELO detector, originally developed for the LHCb experiment, was tested as an online beam monitor at the Clatterbridge Cancer Center in the UK. The design of both monitors is presented in this contribution. Results from measurements are discussed and complemented by numerical studies into the performance limits of either technique.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA005  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOPWI004 Novel Single Shot Bunch Length Diagnostic using Coherent Diffraction Radiation 1150
 
  • R.B. Fiorito, C.P. Welsch, H.D. Zhang
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • A.G. Shkvarunets
    UMD, College Park, Maryland, USA
 
  Funding: European Union’s grant agreement no. 624890 and STFC Cockcroft core grant No. ST/G008248/1; US Office of Naval Research and DOD Joint Technology Office.
Current beam bunch length monitors which measure the spectral content of beam-associated coherent radiation to determine the longitudinal bunch form factor usually require wide bandwidth detection or Fourier transformation of interferometric data and multiple beam pulses. The data must then be Fourier transformed to obtain the bunch length. In this contribution we discuss progress in the development of a novel single shot method that utilizes the frequency integrated angular distribution (AD) of coherent diffraction radiation (CDR) to measure the RMS bunch length directly. We also present simulation results which show how the AD changes with bunch length for several electron beam linacs, where we are planning to test this new method, our single shot measurement technique and plans for comparison to other bunch length monitors.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI004  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
MOPWI006 Development of a Supersonic Gas-jet Monitor to Measure Beam Profile Non-destructively 1157
 
  • H.D. Zhang, A. Jeff, V. Tzoganis, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • A. Jeff
    CERN, Geneva, Switzerland
  • A. Jeff, V. Tzoganis, C.P. Welsch, H.D. Zhang
    The University of Liverpool, Liverpool, United Kingdom
  • V. Tzoganis
    RIKEN, Saitama, Japan
 
  Funding: This project is supported by Helmholtz Association(VH-NG-328), EU’s 7th Framework Program for research, technological development and demonstration( 215080) and STFC Cockcroft core grant(ST/G008248/1).
The measurement of the transverse beam profile is a great challenge for high intensity, high brightness and high power particle beams due to their destructive power. Current non-destructive methods such as residual gas monitors and beam induced fluorescence monitors either require a rather long integration time or residual gas pressures in the order of 10-7 mbar to make meaningful measurements. A supersonic gas-jet beam profile monitor has been developed by QUASAR group at the Cockcroft Institute, UK and promises significant improvements over these established techniques. In this monitor, a supersonic gas curtain is generated that crosses the beam to be analyzed under an angle of 45°. When both beams interact, ionization of the gas jet particles occurs and these ions are then accelerated by an electrostatic extraction field towards a Micro Channel Plate (MCP). Beam images are then obtained via a phosphor screen-CCD camera combination. In this contribution, we discuss the monitor design and present beam profile measurements of a 5 keV electron beam. These are complemented by results from measurements using a pulsed valve to study the gas jet dynamics.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI006  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPJE074 LCLS Injector Laser Modulation to Improve FEL Operation Efficiency and Performance 1813
 
  • S. Li, D.K. Bohler, W.J. Corbett, A.S. Fisher, S. Gilevich, Z. Huang, A. Li, D.F. Ratner, J. Robinson, F. Zhou
    SLAC, Menlo Park, California, USA
  • R.B. Fiorito, E.J. Montgomery
    UMD, College Park, Maryland, USA
  • H.D. Zhang
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • H.D. Zhang
    The University of Liverpool, Liverpool, United Kingdom
 
  In the Linear Coherent Light Source (LCLS) at SLAC, the injector laser plays an important role as the source of the electron beam for the Free Electron Laser (FEL). The injector laser strikes a copper photocathode which emits photo-electrons due to photo-electric effect. The emittance of the electron beam is highly related to the transverse shape of the injector laser. Currently the LCLS injector laser has hot spots that degrade the FEL performance. The goal of this project is to use adaptive optics to modulate the transverse shape of the injector laser, in order to produce a desired shape of electron beam. With a more controllable electron transverse profile, we can achieve lower emittance for the FEL, improve the FEL performance and operation reliability. We first present various options for adaptive optics and damage test results. Then we will discuss the shaping process with an iterative algorithm to achieve the desired shape, characterized by Zernike polynomial deconstruction.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE074  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)