BIW2012 - List of Authors (Behrens, C.)

Paper

Title

Page

Fast Bunch Profile Monitoring with THz Spectroscopy of Coherent Radiation at FLASH

256

S. Wesch, C. Behrens, B. Schmidt
DESY, Hamburg, Germany
E. Hass
Uni HH, Hamburg, Germany

We developed a fast bunch profile monitor based on wavelength-resolved THz detection. An in-vacuum spectrometer with four dispersive gratings and parallel readout of 120 individual wavelength bins provides detailed shot-to-shot information on the bunch shape. The device can be operated in short (5-44 um) and long range (45-435 um) mode to cover the entire longitudinal phase space for compressed bunches of the FLASH linac. Due to the large wavelength range, the electron bunch time profile can be reconstructed reliably in detail using Kramers-Kronig algorithm for the phase retrieval. Performance of the instrument and results compared to direct time domain (TDS) measurements will be presented for electron bunches down to a few 10th femtoseconds length.

Slides THAP01 [7.475 MB]

THBP01

Ultra-short Electron Bunch and X-ray Temporal Diagnostics with an X-band Transverse Deflecting Cavity

264

P. Krejcik, Y.T. Ding, J.C. Frisch, Z. Huang, H. Loos, J.W. Wang, M.-H. Wang
SLAC, Menlo Park, California, USA
C. Behrens
DESY, Hamburg, Germany
P. Emma
LBNL, Berkeley, California, USA

Funding: This work was supported by Department of Energy Contract No. DE-AC0276SF00515.
The technique of streaking an electron bunch with a RF deflecting cavity to measure its bunch length is being applied in a new way at the Linac Coherent Light Source with the goal of measuring the femtosecond temporal profile of the FEL photon beam. A powerful X-band deflecting cavity is being installed downstream of the FEL undulator and the streaked electron beam will be observed at an energy spectrometer screen at the beam dump. The single-shot measurements will reveal which time slices of the streaked beam have contributed to the FEL process by virtue of their greater energy loss and energy spread relative to the non-lasing portions of the electron bunch. Since the diagnostic is located downstream of the undulator it can be operated continuously without interrupting the beam to the users. The resolution of the new X-band system will be compared to the existing S-band RF deflecting diagnostic systems at SLAC and consideration is given to the required RF phase stability tolerances required for acceptable beam jitter on the monitor. Simulation studies show that about 1 fs (rms) time resolution is achievable in the LCLS over a wide range of FEL wavelengths and pulse lengths.

Paper	Title	Page
THAP01	Fast Bunch Profile Monitoring with THz Spectroscopy of Coherent Radiation at FLASH	256
	S. Wesch, C. Behrens, B. Schmidt DESY, Hamburg, Germany E. Hass Uni HH, Hamburg, Germany
	We developed a fast bunch profile monitor based on wavelength-resolved THz detection. An in-vacuum spectrometer with four dispersive gratings and parallel readout of 120 individual wavelength bins provides detailed shot-to-shot information on the bunch shape. The device can be operated in short (5-44 um) and long range (45-435 um) mode to cover the entire longitudinal phase space for compressed bunches of the FLASH linac. Due to the large wavelength range, the electron bunch time profile can be reconstructed reliably in detail using Kramers-Kronig algorithm for the phase retrieval. Performance of the instrument and results compared to direct time domain (TDS) measurements will be presented for electron bunches down to a few 10th femtoseconds length.
	Slides THAP01 [7.475 MB]

THBP01	Ultra-short Electron Bunch and X-ray Temporal Diagnostics with an X-band Transverse Deflecting Cavity	264
	P. Krejcik, Y.T. Ding, J.C. Frisch, Z. Huang, H. Loos, J.W. Wang, M.-H. Wang SLAC, Menlo Park, California, USA C. Behrens DESY, Hamburg, Germany P. Emma LBNL, Berkeley, California, USA
	Funding: This work was supported by Department of Energy Contract No. DE-AC0276SF00515. The technique of streaking an electron bunch with a RF deflecting cavity to measure its bunch length is being applied in a new way at the Linac Coherent Light Source with the goal of measuring the femtosecond temporal profile of the FEL photon beam. A powerful X-band deflecting cavity is being installed downstream of the FEL undulator and the streaked electron beam will be observed at an energy spectrometer screen at the beam dump. The single-shot measurements will reveal which time slices of the streaked beam have contributed to the FEL process by virtue of their greater energy loss and energy spread relative to the non-lasing portions of the electron bunch. Since the diagnostic is located downstream of the undulator it can be operated continuously without interrupting the beam to the users. The resolution of the new X-band system will be compared to the existing S-band RF deflecting diagnostic systems at SLAC and consideration is given to the required RF phase stability tolerances required for acceptable beam jitter on the monitor. Simulation studies show that about 1 fs (rms) time resolution is achievable in the LCLS over a wide range of FEL wavelengths and pulse lengths.