FEL2011 - Table of Session: THOA (FEL Technology II)

Paper

Title

Page

Pushing the Limits of Short Period Permanent Magnet Undulators

435

J. Bahrdt
HZB, Berlin, Germany

Short period undulators to be used as FEL radiators permit lower electron energies and, thus, reduce linac and undulator lengths. The first X-ray FEL facility based on in-vacuum undulators goes into operation soon (SPRING-8 XFEL). Other in-vacuum undulator based FELs are under construction (SWISS-FEL) or are planned. The in-vacuum undulators have period lengths between 18mm (SPRING-8-X-FEL) and 15mm (SWISS-FEL). In the future the period length will be pushed further into the sub-cm regime. The technical implications of these devices will be discussed: New materials such as PrFeB-magnets are employed. They show their superior characteristics at cryogenic temperatures. Geometric and magnetic tolerances will be tighter and the construction and shimming concepts have to be revised. New magnetic measurement systems are required as well. Recently, a 9mm period length 20 period prototype undulator has been built in collaboration between Ludwig-Maximilian-University Munich and Helmholtz-Zentrum Berlin. The potential and the challenges of sub-cm undulators will be illustrated based on first results from this prototype.

Slides THOAI1 [3.344 MB]

THOAI2

Development of Superconducting Undulators

S. Prestemon, D. Arbelaez, T. Koettig, A. Madur, S. Marks, D. Schlueter
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director of the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Undulator technology plays a critical role in FEL performance. The desire to provide a specific range of photon wavelengths for science applications constrains the design space of electron beam energy and undulator tuning capabilities. In particular, the coupling between photon wavelength, beam energy, and undulator period and strength indicates that undulator technology is a major cost driver in the design of FEL facilities. Superconducting undulators have the potential to significantly improve upon performance of current state-of-the-art undulator technologies being implemented in the first FEL facilities. Here we review the status of superconducting undulator technology, including developments in the areas of helical, planar, and variable polarizing superconducting undulator concepts at a variety of laboratories around the world. Implications of superconducting undulator performance for FEL applications are described. Finally, the major technological hurdles that remain to be addressed prior to implementation in FEL facilities are outlined, together with a summary of current R&D efforts.

Slides THOAI2 [3.891 MB]

THOA3

Demonstration of Transverse-to-longitudinal Emittance Exchange at A0 Photoinjector

443

J. Ruan, A.S. Johnson, A.H. Lumpkin, Y.-E. Sun, R.M. Thurman-Keup
Fermilab, Batavia, USA

The 3-D phase-space manipulation of electron beams enhances the performance of next generation accelerators including high energy colliders and accelerator based light sources. In this paper we will report an observation of near ideal transverse to longitudinal emittance exchange at the Fermilab A0 Photoinjector. The emittance exchange (EEX) beamline consists a 3.9 GHz normal conducting deflecting mode cavity positioned between two magnetic doglegs. We will also compare the experiment results to simulations.

THOA4

Three Bunch Compressor Scheme for SASE FEL

447

H.-S. Kang, I.S. Ko, S.H. Nam
PAL, Pohang, Kyungbuk, Republic of Korea
M.-H. Cho, C.H. Yi
POSTECH, Pohang, Kyungbuk, Republic of Korea

The bend angle of dipoles in bunch compressor needs to be small enough to reduce the emittance increase due to CSR, which requires a larger energy chirp at the preceding RF linac. Correlated energy spread is not reduced below FEL parameter after the following RF linac because of the small number of accelerating sections as in the PAL XFEL design. Three bunch compressor scheme can make it possible to minimize the CSR induced emittnace growth as well as reduce the correlated energy spread below FEL parameter.

Slides THOA4 [1.467 MB]

Paper	Title	Page
THOAI1	Pushing the Limits of Short Period Permanent Magnet Undulators	435
	J. Bahrdt HZB, Berlin, Germany
	Short period undulators to be used as FEL radiators permit lower electron energies and, thus, reduce linac and undulator lengths. The first X-ray FEL facility based on in-vacuum undulators goes into operation soon (SPRING-8 XFEL). Other in-vacuum undulator based FELs are under construction (SWISS-FEL) or are planned. The in-vacuum undulators have period lengths between 18mm (SPRING-8-X-FEL) and 15mm (SWISS-FEL). In the future the period length will be pushed further into the sub-cm regime. The technical implications of these devices will be discussed: New materials such as PrFeB-magnets are employed. They show their superior characteristics at cryogenic temperatures. Geometric and magnetic tolerances will be tighter and the construction and shimming concepts have to be revised. New magnetic measurement systems are required as well. Recently, a 9mm period length 20 period prototype undulator has been built in collaboration between Ludwig-Maximilian-University Munich and Helmholtz-Zentrum Berlin. The potential and the challenges of sub-cm undulators will be illustrated based on first results from this prototype.
	Slides THOAI1 [3.344 MB]

THOAI2	Development of Superconducting Undulators
	S. Prestemon, D. Arbelaez, T. Koettig, A. Madur, S. Marks, D. Schlueter LBNL, Berkeley, California, USA
	Funding: This work was supported by the Director of the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Undulator technology plays a critical role in FEL performance. The desire to provide a specific range of photon wavelengths for science applications constrains the design space of electron beam energy and undulator tuning capabilities. In particular, the coupling between photon wavelength, beam energy, and undulator period and strength indicates that undulator technology is a major cost driver in the design of FEL facilities. Superconducting undulators have the potential to significantly improve upon performance of current state-of-the-art undulator technologies being implemented in the first FEL facilities. Here we review the status of superconducting undulator technology, including developments in the areas of helical, planar, and variable polarizing superconducting undulator concepts at a variety of laboratories around the world. Implications of superconducting undulator performance for FEL applications are described. Finally, the major technological hurdles that remain to be addressed prior to implementation in FEL facilities are outlined, together with a summary of current R&D efforts.
	Slides THOAI2 [3.891 MB]

THOA3	Demonstration of Transverse-to-longitudinal Emittance Exchange at A0 Photoinjector	443
	J. Ruan, A.S. Johnson, A.H. Lumpkin, Y.-E. Sun, R.M. Thurman-Keup Fermilab, Batavia, USA
	The 3-D phase-space manipulation of electron beams enhances the performance of next generation accelerators including high energy colliders and accelerator based light sources. In this paper we will report an observation of near ideal transverse to longitudinal emittance exchange at the Fermilab A0 Photoinjector. The emittance exchange (EEX) beamline consists a 3.9 GHz normal conducting deflecting mode cavity positioned between two magnetic doglegs. We will also compare the experiment results to simulations.

THOA4	Three Bunch Compressor Scheme for SASE FEL	447
	H.-S. Kang, I.S. Ko, S.H. Nam PAL, Pohang, Kyungbuk, Republic of Korea M.-H. Cho, C.H. Yi POSTECH, Pohang, Kyungbuk, Republic of Korea
	The bend angle of dipoles in bunch compressor needs to be small enough to reduce the emittance increase due to CSR, which requires a larger energy chirp at the preceding RF linac. Correlated energy spread is not reduced below FEL parameter after the following RF linac because of the small number of accelerating sections as in the PAL XFEL design. Three bunch compressor scheme can make it possible to minimize the CSR induced emittnace growth as well as reduce the correlated energy spread below FEL parameter.
	Slides THOA4 [1.467 MB]