Keyword: gun
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TUP005 Commissioning the Beam-Loss Monitoring System of the LCLS Superconducting Linac linac, cryomodule, MMI, radiation 187
  • A.S. Fisher, N. Balakrishnan, G.W. Brown, E.P. Chin, W.G. Cobau, J.E. Dusatko, B.T. Jacobson, S. Kwon, J.A. Mock, J. Park, J. Pigula, E. Rodriguez, J.I.D. Rudolph, D. Sanchez, L. Sapozhnikov, J.J. Welch
    SLAC, Menlo Park, California, USA
  A 4-GeV superconducting linac has been added to the LCLS x-ray FEL facility at SLAC. Its 120-kW, 1-MHz beam requires new beam-loss monitors (BLMs) for radiation protection, machine protection, and diagnostics. Long radiation-hard optical fibres span the full 4 km from the electron gun of the SC linac to the final beam dump. Diamond detectors at anticipated loss points provide local protection. Detector signals are continuously integrated with a 500-ms time constant and compared to a loss threshold. If crossed, the beam is halted within 0.1 ms. Commissioning began in March 2022 with the 100-MeV injector and with RF processing of the cryomodules. At IBIC 2022 last September, we presented commissioning results from the injector BLMs. In October, the beam passed through the full linac and the bypass transport line above the LCLS copper linac, stopping at an intermediate dump. In August it continued through the soft x-ray undulator and achieved first lasing. Here we present BLM commissioning at energies up to 4 GeV and rates up to 100 kHz. We discuss measurements and software using the fast diagnostic-waveform output to localize beam losses and to detect wire-scanner signals.  
poster icon Poster TUP005 [2.620 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2023-TUP005  
About • Received ※ 06 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 27 September 2023
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TUP027 Microbunching of Thermionic Cathode RF Gun Beams in the Advanced Photon Source S-Band Linac linac, bunching, electron, radiation 240
  • J.C. Dooling, A.R. Brill, N. Kuklev, I. Lobach, A.H. Lumpkin, N. Sereno, Y. Sun
    ANL, Lemont, Illinois, USA
  Funding: Work supported by the U.S. D.O.E.,Office of Science, Office of Basic Energy Sciences, under contract number DE-AC02- 06CH11357.
We report on measurements of beams from thermionic cathode (TC) rf guns in the Advanced Photon Source S-Band Linac. These measurements include the macropulse out of both new and existing TC guns as well as the observation of microbunching within the micropulses of these beams. A gun chopper limits the macropulse FWHM duration to the 10-ns range. Our objectives were to analyse the new TC gun and investigate microbunching within a TC-rf-gun-generated beam. Our diagnostics elucidated longitudinal beam structures from the ns to the fs time scales. Coherent transition radiation (CTR) interferometers responding to far-infrared wavelengths were employed after each compression stage to provide the autocorrelations of the sub-ps micropulse durations. The first compression stage is an alpha magnet and the second a chicane. A CCD camera was used to image the beam via optical transition radiation from an Al screen at the end of the linac and also employed to measure coherent optical transition radiation (COTR) in the visible range. The COTR diagnostic observations, implying microbunching on a fs time scale, are presented and compared with a longitudinal space-charge impedance model.
poster icon Poster TUP027 [3.649 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2023-TUP027  
About • Received ※ 15 July 2023 — Revised ※ 08 September 2023 — Accepted ※ 12 September 2023 — Issue date ※ 23 September 2023
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WEP023 Progress on an Electron Beam Profile Monitor at the Fermilab Main Injector electron, proton, experiment, target 395
  • R.M. Thurman-Keup, T.V. Folan, M.W. Mwaniki, S.G. Sas-Pawlik
    Fermilab, Batavia, Illinois, USA
  Funding: This work was produced by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
The current program at Fermilab involves the construction of a new superconducting linear accelerator (LINAC) to replace the existing warm version. The new LINAC, together with other planned improvements, is in support of proton beam intensities in the Main Injector (MI) that will exceed 2 MW. Measuring the transverse profiles of these high intensity beams in a ring requires non-invasive techniques. The MI uses ionization profile monitors as its only profile system. An alternative technique involves measuring the deflection of a probe beam of electrons with a trajectory perpendicular to the proton beam. This type of device was installed in MI and initial studies of it have been previously presented. This paper will present the status and recent studies of the device utilizing different techniques.
poster icon Poster WEP023 [3.243 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2023-WEP023  
About • Received ※ 08 September 2023 — Revised ※ 09 September 2023 — Accepted ※ 14 September 2023 — Issue date ※ 14 September 2023
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