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| IT05 |
Single Shot Electron-Beam Bunch Length Measurements
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diagnostics, instrumentation, monitoring, electro-magnetic fields, electron |
20 |
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- G. Berden, G.M.H. Knippels, D. Oepts, A.F.G. van der Meer
FOM, Institute for Plasma Physics 'Rijnhuizen', Nieuwegein, The Netherlands
- S.P. Jamison, X. Yan, A.M. MacLeod, W.A. Gillespie
Abertay, University of Abertay Dundee, Dundee, UK
- J.L. Shen
CNU, Capital Normal University, Beijing, China
- I. Wilke
RPI, Rensselaer Polytechnic Institute, Troy, NY, USA
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It is recognised by the Instrumentation community that 4th generation
light sources (like TESLA, LCLS) are posing some of the most stringent
requirements on beam diagnostics. Among these, the single-shot
electro-optic measurement of the bunch length and shape in the
sub-picosecond domain is an ongoing development.
The electro-optic detection method makes use of the fact that the local
electric field of a highly relativistic electron bunch moving in a
straight line is almost entirely concentrated perpendicular to its
direction of motion. This electric field makes an electro-optic crystal
placed in the vicinity of the beam birefringent. The amount of
birefringence depends on the electric field and is probed by monitoring
the change of polarization of the wavelength components of a chirped,
synchronized Ti:sapphire laser pulse.
This talk will provide details of the experimental setup at the Free
Electron Laser for Infrared eXperiments (FELIX) in Nieuwegein, The
Netherlands, where single shot images have been obtained of 1.7 ps long
electron bunches (beam energy 46 MeV, charge per bunch 200 pC).
Furthermore, future upgrading possibilities will be discussed.
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| CT11 |
Beam Based HOM Analysis of Acceleating Structures at the TESLA Test Facility LINAC
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diagnostics, instrumentation, linac, higher-order-mode |
83 |
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- M. Wendt, S. Schreiber, A. Gössel
DESY, Deutsches Elektronen-Synchrotron, Hamburg, Germany
- M. Hüning
FNAL, Fermi National Accelerator Laboratory, Batavia, IL, USA
- G. Devanz, M. Jablonka, C. Magne, O. Napoly
CEA, Commissariat à l'Energie Atomique, Saclay, France
- N. Baboi* (on leave from NTLPRP)
SLAC, Stanford Linear Accelerator, Stanford, CA, USA
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The beam emittance in future linear accelerators for high energy physics
and SASE-FEL applications depends highly on the field performance in the
accelerating structures, i.e. the damping of higher order modes (HOM).
Besides theoretical and laboratory analysis (network analyzer), a beam
based analysis technique was established [S. Fartoukh, et.al.,
Proceedings of the PAC99 Conference] at the TESLA Test Facility (TTF)
linac. It uses a charge modulated beam of variable modulation frequency
to excite dipole modes. This causes a modulation of the transverse beam
displacement, which is observed at a downstream BPM and associated with a
direct analysis of the modes at the HOM couplers. Emphasis of this
presentation is put on beam instrumentation and signal analysis aspects.
A brief introduction of eigenmodes in resonant structures, as well as
some interesting measurement results are further presented.
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