FEL2015 - Table of Session: TUD (FEL Tech. & Hardware : Electron Diag., Timing, Synchronization, and Controls)

Paper

Title

Page

COTR Resistant Profile Monitor

554

H. Loos
SLAC, Menlo Park, California, USA

Funding: Work supported by DOE contract DE-AC02-76SF00515
Electron beam accelerators used as drivers for short wavelength FELs need ultra-high brightness beams with small emittances and highly compressed bunch lengths. The acceleration and beam transport process of such beams leads to micro-bunching instabilities which cause the emergence of coherent optical transition radiation (COTR). The effect of COTR on profile monitors based on OTR or fluorescent screens can be quite detrimental to their intended use to measure beam sizes and profiles. This presentation will review past observations of the beam diagnostics issues due to COTR and discuss various mitigation schemes for profile monitors as well as present experience with such implementations.

Slides TUD01 [1.536 MB]

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TUD02

Diffraction Radiation Monitor

561

Y. Taira
AIST, Tsukuba, Japan

Non-invasive beam diagnostics using a diffraction radiation (DR) has been developed at several electron accelerator facilities. Generation process of DR is similar to that of transition radiation (TR). TR is emitted when a charged particle passes through the boundary between two media with different dielectric constants. On the other hand, DR is emitted when it passes through in the vicinity of a boundary between two media. In the generation process of DR, the charged particle doesn't intersect the medium but its electric field intersects the medium. An aperture, a slit, and an edge are used for DR target. Optical wavelength of DR is usually used for beam diagnostics. One can evaluate energy, a transverse beam size, and a divergence of an electron beam by measuring a spatial distribution of DR. Moreover, coherent diffraction radiation with the wavelength of less than millimeter range is used for a bunch length measurement. In this conference, a theoretical background of DR and experimental results carried out at several facilities will be presented.

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TUD03

First Results of the SRF Gun Test for CeC PoP Experiment

564

I. Pinayev, Z. Altinbas, S.A. Belomestnykh, K.A. Brown, J.C. Brutus, A.J. Curcio, A. Di Lieto, C. Folz, D.M. Gassner, M. Harvey, J.P. Jamilkowski, Y.C. Jing, D. Kayran, R. Kellermann, R.F. Lambiase, V. Litvinenko, G.J. Mahler, M. Mapes, W. Meng, T.A. Miller, M.G. Minty, G. Narayan, P. Orfin, T. Rao, J. Reich, B. Sheehy, J. Skaritka, L. Smart, K.S. Smith, L. Snydstrup, V. Soria, R. Than, C. Theisen, J.E. Tuozzolo, E. Wang, G. Wang, B. P. Xiao, T. Xin, W. Xu, A. Zaltsman
BNL, Upton, Long Island, New York, USA

We have started the first tests of the equipment for the coherent electron cooling proof-of-principle experiment. After tests of the 500 MHz normal conducting cavities we proceeded with the low power beam tests of a CW SRF gun. The results of the tests with record beam parameters are presented.

Slides TUD03 [1.201 MB]

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TUD04

Relative Bunch Length Measurements at MAX IV Linac

F. Curbis, E. Mansten, D.F. Olsson, S. Thorin
MAX-lab, Lund, Sweden

The commission of the MAX IV linac recently started and among other features, some attention has been dedicated to the characterization of the bunch length compression. Instead of the most commonly used magnetic chicanes, in the MAX IV linac two double achromats can compress the photo-cathode beam from a few ps to hundred fs level. Since the linac is not yet equipped with dedicated diagnostics for absolute bunch measurements, we performed relative measurement of the bunch length. We take advantage of the transition radiation emitted by the bunch when crossing a ceramic gap discontinuity, which is situated after the bunch compressors. The signal is picked up by horn antennas and directed to diodes sensitive to different frequencies. In this contribution we show the first experimental results and the comparison with simulations of our specific geometry.

Slides TUD04 [3.381 MB]

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Paper	Title	Page
TUD01	COTR Resistant Profile Monitor	554
	H. Loos SLAC, Menlo Park, California, USA
	Funding: Work supported by DOE contract DE-AC02-76SF00515 Electron beam accelerators used as drivers for short wavelength FELs need ultra-high brightness beams with small emittances and highly compressed bunch lengths. The acceleration and beam transport process of such beams leads to micro-bunching instabilities which cause the emergence of coherent optical transition radiation (COTR). The effect of COTR on profile monitors based on OTR or fluorescent screens can be quite detrimental to their intended use to measure beam sizes and profiles. This presentation will review past observations of the beam diagnostics issues due to COTR and discuss various mitigation schemes for profile monitors as well as present experience with such implementations.
	Slides TUD01 [1.536 MB]
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

TUD02	Diffraction Radiation Monitor	561
	Y. Taira AIST, Tsukuba, Japan
	Non-invasive beam diagnostics using a diffraction radiation (DR) has been developed at several electron accelerator facilities. Generation process of DR is similar to that of transition radiation (TR). TR is emitted when a charged particle passes through the boundary between two media with different dielectric constants. On the other hand, DR is emitted when it passes through in the vicinity of a boundary between two media. In the generation process of DR, the charged particle doesn't intersect the medium but its electric field intersects the medium. An aperture, a slit, and an edge are used for DR target. Optical wavelength of DR is usually used for beam diagnostics. One can evaluate energy, a transverse beam size, and a divergence of an electron beam by measuring a spatial distribution of DR. Moreover, coherent diffraction radiation with the wavelength of less than millimeter range is used for a bunch length measurement. In this conference, a theoretical background of DR and experimental results carried out at several facilities will be presented.
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

TUD03	First Results of the SRF Gun Test for CeC PoP Experiment	564
	I. Pinayev, Z. Altinbas, S.A. Belomestnykh, K.A. Brown, J.C. Brutus, A.J. Curcio, A. Di Lieto, C. Folz, D.M. Gassner, M. Harvey, J.P. Jamilkowski, Y.C. Jing, D. Kayran, R. Kellermann, R.F. Lambiase, V. Litvinenko, G.J. Mahler, M. Mapes, W. Meng, T.A. Miller, M.G. Minty, G. Narayan, P. Orfin, T. Rao, J. Reich, B. Sheehy, J. Skaritka, L. Smart, K.S. Smith, L. Snydstrup, V. Soria, R. Than, C. Theisen, J.E. Tuozzolo, E. Wang, G. Wang, B. P. Xiao, T. Xin, W. Xu, A. Zaltsman BNL, Upton, Long Island, New York, USA
	We have started the first tests of the equipment for the coherent electron cooling proof-of-principle experiment. After tests of the 500 MHz normal conducting cavities we proceeded with the low power beam tests of a CW SRF gun. The results of the tests with record beam parameters are presented.
	Slides TUD03 [1.201 MB]
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)

TUD04	Relative Bunch Length Measurements at MAX IV Linac
	F. Curbis, E. Mansten, D.F. Olsson, S. Thorin MAX-lab, Lund, Sweden
	The commission of the MAX IV linac recently started and among other features, some attention has been dedicated to the characterization of the bunch length compression. Instead of the most commonly used magnetic chicanes, in the MAX IV linac two double achromats can compress the photo-cathode beam from a few ps to hundred fs level. Since the linac is not yet equipped with dedicated diagnostics for absolute bunch measurements, we performed relative measurement of the bunch length. We take advantage of the transition radiation emitted by the bunch when crossing a ceramic gap discontinuity, which is situated after the bunch compressors. The signal is picked up by horn antennas and directed to diodes sensitive to different frequencies. In this contribution we show the first experimental results and the comparison with simulations of our specific geometry.
	Slides TUD04 [3.381 MB]
Export •	reference for this paper to ※ LaTeX, ※ Text, ※ IS/RefMan, ※ EndNote (xml)