Author: Brosi, M.
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MOPHA023 Observation of Coherent Pulses in the Sub-THz Range at DELTA 823
 
  • C. Mai, F.H. Bahnsen, M. Bolsinger, S. Hilbrich, M. Huck, M. Höner, S. Khan, A. Meyer auf der Heide, R. Molo, H. Rast, G. Shayeganrad, P. Ungelenk
    DELTA, Dortmund, Germany
  • M. Brosi, B. Kehrer, A.-S. Müller, M.J. Nasse, P. Schönfeldt, P. Schütze, S. Walther
    KIT, Karlsruhe, Germany
  • H. Huck
    DESY Zeuthen, Zeuthen, Germany
 
  Funding: Work supported by the BMBF (05K13PEC).
Coherent ultrashort THz pulses induced by a laser-electron interaction are routinely produced and observed at DELTA, a 1.5-GeV synchrotron light source operated by the TU Dortmund University. The turn-by-turn evolution of the radiation spectrum is known to shift to the sub-THz regime after the initial laser-electron interaction. Recently, an ultrafast YBCO-based THz detector has been permanently installed and a Schottky diode has been tested at the THz beamline. Measurements with these detectors showing the temporal evolution of the coherent signals after several revolutions are presented. Furthermore, the concept of a recently designed Fourier-transform spectrometer optimized for the sub-THz region is shown.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA023  
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MOPHA042 Online Studies of THz-radiation in the Bursting Regime at ANKA 882
 
  • M. Brosi, C.M. Caselle, E. Hertle, N. Hiller, A. Kopmann, A.-S. Müller, M. Schwarz, P. Schönfeldt, J.L. Steinmann, M. Weber
    KIT, Karlsruhe, Germany
 
  Funding: This work has been supported by the Initiative and Networking Fund of the Helmholtz Association under contract number VH-NG-320
The ANKA storage ring of the Karlsruhe Institute of Technology (KIT) operates in the energy range from 0.5 to 2.5 GeV and generates brilliant coherent synchrotron radiation in the THz range with a dedicated bunch length reducing optic. The producing of radiation in the so-called THz-gap is challenging, but this intense THz radiation is very attractive for certain user experiments. The high degree of compression in this so-called low-alpha optics leads to a complex longitudinal dynamics of the electron bunches. The resulting micro-bunching instability leads to time dependent fluctuations and strong bursts in the radiated THz power. The study of these fluctuations in the emitted THz radiation provides insight into the longitudinal beam dynamics. Fast THz detectors combined with KAPTURE, the dedicated KArlsruhe Pulstaking and Ultrafast Readout Electronics system developed at KIT, allow the simultaneous measurement of the radiated THz intensity for each bunch individually in a multi-bunch environment. This contribution gives an overview of the first experience gained using this setup as an online diagnostics tool.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA042  
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TUPWA043 Non-interferometric Spectral Analysis of Synchrotron Radiation in the THz regime at ANKA 1509
 
  • J.L. Steinmann, M. Brosi, E. Bründermann, C.M. Caselle, E. Hertle, N. Hiller, B. Kehrer, A.-S. Müller, M. Schuh, M. Schwarz, P. Schönfeldt, P. Schütze
    KIT, Karlsruhe, Germany
  • J.L. Hesler
    Virginia Diodes Inc., Charlottesville, USA
 
  Interferometry is the quasi-standard for spectral measurements in the THz- and IR-range. The frequency resolution, however, is limited by the travel range of the interferometer mirrors. Therefore, a resolution in the low megahertz range would require interferometer arms of about 100 m. As an alternative, heterodyne measurements provide a resolution in the Hertz range, an improvement of 6 orders of magnitude. Here we present measurements done at ANKA with a VDI WR3.4SAX, a mixer that can be tuned to frequencies from 220 GHz to 330 GHz and we show how the bunch filling pattern influences the amplitude of specific frequencies.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA043  
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