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Microbunch preserving in-line system for an APPLE II helical radiator at the LCLS baseline

Abstract

In a previous work we proposed a scheme for polarization control at the LCLS baseline, which exploited the microbunching from the planar undulator. After the baseline undulator, the electron beam is transported through a drift by a FODO focusing system, and through a short helical radiator. The microbunching structure can be preserved, and intense coherent radiation is emitted in the helical undulator at fundamental harmonic. The driving idea of this proposal is that the background linearly-polarized radiation from the baseline undulator is suppressed by spatial filtering. Filtering is achieved by letting radiation and electron beam through Be slits upstream of the helical radiator, where the radiation spot size is about ten times larger than the electron beam transverse size. Several changes considered in the present paper were made to improve the previous design. Slits are now placed immediately behind the helical radiator. The advantage is that the electron beam can be spoiled by the slits, and narrower slits width can be used for spatial filtering. Due to this fundamental reason, the present setup is shorter than the previous one. The helical radiator is now placed immediately behind the SHAB undulator. It is thus sufficient to use the existing FODO focusing  More>>
Authors:
Geloni, Gianluca; [1]  Kocharyan, Vitali; Saldin, Evgeni [2] 
  1. European XFEL Project Team, Hamburg (Germany)
  2. Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
Publication Date:
May 15, 2011
Product Type:
Technical Report
Report Number:
DESY-11-083
Subject:
43 PARTICLE ACCELERATORS; ANGULAR DISTRIBUTION; BEAM BUNCHING; BEAM EMITTANCE; BEAM PRODUCTION; BEAM PROFILES; BEAM TRANSPORT; COHERENT RADIATION; ELECTROMAGNETIC PULSES; ELECTRON BEAMS; EV RANGE 100-1000; FOCUSING; FREE ELECTRON LASERS; G CODES; GEV RANGE 01-10; HELICAL CONFIGURATION; LASER RADIATION; MODULATION; ONDULATOR RADIATION; PHOTON BEAMS; POLARIZATION; POLARIZED BEAMS; SOFT X RADIATION; WIGGLER MAGNETS; X-RAY LASERS
OSTI ID:
21461393
Research Organizations:
Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)
Country of Origin:
Germany
Language:
English
Other Identifying Numbers:
Other: ISSN 0418-9833; TRN: DE11F7726
Availability:
Commercial reproduction prohibited; INIS; OSTI as DE21461393
Submitting Site:
DEN
Size:
13 pages
Announcement Date:
Jul 29, 2011

Citation Formats

Geloni, Gianluca, Kocharyan, Vitali, and Saldin, Evgeni. Microbunch preserving in-line system for an APPLE II helical radiator at the LCLS baseline. Germany: N. p., 2011. Web.
Geloni, Gianluca, Kocharyan, Vitali, & Saldin, Evgeni. Microbunch preserving in-line system for an APPLE II helical radiator at the LCLS baseline. Germany.
Geloni, Gianluca, Kocharyan, Vitali, and Saldin, Evgeni. 2011. "Microbunch preserving in-line system for an APPLE II helical radiator at the LCLS baseline." Germany.
@misc{etde_21461393,
title = {Microbunch preserving in-line system for an APPLE II helical radiator at the LCLS baseline}
author = {Geloni, Gianluca, Kocharyan, Vitali, and Saldin, Evgeni}
abstractNote = {In a previous work we proposed a scheme for polarization control at the LCLS baseline, which exploited the microbunching from the planar undulator. After the baseline undulator, the electron beam is transported through a drift by a FODO focusing system, and through a short helical radiator. The microbunching structure can be preserved, and intense coherent radiation is emitted in the helical undulator at fundamental harmonic. The driving idea of this proposal is that the background linearly-polarized radiation from the baseline undulator is suppressed by spatial filtering. Filtering is achieved by letting radiation and electron beam through Be slits upstream of the helical radiator, where the radiation spot size is about ten times larger than the electron beam transverse size. Several changes considered in the present paper were made to improve the previous design. Slits are now placed immediately behind the helical radiator. The advantage is that the electron beam can be spoiled by the slits, and narrower slits width can be used for spatial filtering. Due to this fundamental reason, the present setup is shorter than the previous one. The helical radiator is now placed immediately behind the SHAB undulator. It is thus sufficient to use the existing FODO focusing system of the SHAB undulator for transporting themodulated electron beam. This paper presents complete GENESIS code calculations for the new design, starting from the baseline undulator entrance up to the helical radiator exit including the modulated electron beam transport by the SHAB FODO focusing system. (orig.)}
place = {Germany}
year = {2011}
month = {May}
}