IPAC2012 - List of Keywords (free-electron-laser)

Paper	Title	Other Keywords	Page
MOOAA03	Fast Feedback Strategies for Longitudinal Beam Stabilization	feedback, controls, laser, electron	26
	S. Pfeiffer, M.K. Bock, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany W. Jałmużna TUL-DMCS, Łódź, Poland G. Lichtenberg, H. Werner TUHH, Hamburg, Germany
	The key for pump-probe and seeding experiments at Free Electron Lasers such as FLASH is a femtosecond precise regulation of the bunch arrival time and compression. To maintain this beam based requirements, both for a single bunch and within a bunch train, it is necessary to combine field and beam based feedback loops. We present in this paper an advancement of the currently implemented beam based feedback system at FLASH. The principle of beam based modulation of the RF set point can be superimposed by a direct feedback loop with a beam optimized controller. Recent measurements of the achieved bunch arrival time jitter reduction to 20 fs have shown the performance gain by this direct feedback method . The combination of both approaches will be presented and possible advantages are discussed. C. Schmidt et al., “Feedback Strategies for Bunch Arrival Time Stabilization at FLASH Towards 10 fs,” FEL’2011, Shanghai, August 2011, THPA26, http://www. JACoW.org.
	Slides MOOAA03 [0.544 MB]

MOPPP085	Single Electron Dynamic of Microwave Undulator	electron, undulator, FEL, radiation	753
	C. Chang, J. Neilson, C. Pellegrini, M. Shumail, S.G. Tantawi SLAC, Menlo Park, California, USA
	The analytical and numerical calculations for the dynamic of single electron and beam in RF undulator have been conducted and compared. The transverse and longitudinal velocity, trajectory, energy variation, and the spontaneous radiation are studied. It is found that the forward and backward wave (FW/BW) components have different contribution on electron motion and radiation, most of the energy spread comes from FW component, in other words, the effect of FW on modulating the electron energy is much stronger than that of BW for the same undulating-amplitude value, which mechanism has been analyzed.

MOPPR018	Beam Halo Monitor for FLASH and the European XFEL	electron, diagnostics, laser, pick-up	816
	A. Ignatenko, N. Baboi, O. Hensler, M. Schmitz, K. Wittenburg DESY, Hamburg, Germany H.M. Henschel, W. Lange, W. Lohmann DESY Zeuthen, Zeuthen, Germany A. Ignatenko BTU, Cottbus, Germany S. Schuwalow Uni HH, Hamburg, Germany
	The Beam Halo Monitor for Free-electron Laser in Hamburg (FLASH) based on pCVD diamond and monocrystalline artificial sapphire sensors has been successfully commissioned in September 2009. It is a part of the beam dump diagnostics and ensures safe beam dumping. Its description and the experience gained during its operation are given. The ideas on the design and aspects of operation of the similar systems at FLASH II and the European XFEL are presented.

TUEPPB011	Echo Enabled High Mode Generation for X-ray FELs	laser, electron, bunching, FEL	1140
	E. Hemsing SLAC, Menlo Park, California, USA A. Marinelli UCLA, Los Angeles, California, USA
	Funding: Work supported by U.S. DOE under Contract Nos. DE-AC02-76SF00515 and DE-FG02-07ER46272. We describe a simple technique based on a modified echo-enabled harmonic generation (EEHG) scheme to manipulate the three-dimensional electron beam microbunching distribution in order to generate higher-order optical modes in an FEL. As with EEHG, the concept uses two modulators and two chicanes to produce microbunching. However, in one of the modulators, the resonant interaction with the laser has a well-defined transverse structure that becomes strongly correlated to the longitudinal microbunching distribution. Both high-harmonic frequencies and high transverse mode numbers can be generated through a transversely-dependent echo effect.

TUPPC009	Dihedral Group and Repetitive Achromats with Mirror Symmetric or Mirror Antisymmetric Basic Cell	multipole, electron, resonance, focusing	1170
	V. Balandin, R. Brinkmann, W. Decking, N. Golubeva DESY, Hamburg, Germany
	Using the group-theoretical point of view for the design of magnetic optical achromats as introduced in, we study in this paper second- and third-order repetitive achromats with a mirror symmetric or mirror antisymmetric basic cell. We also compare these achromats with repetitive achromats designed without internal cell symmetries taken into account. V.Balandin, R.Brinkmann, W.Decking, N.Golubeva. Two Cell Repetitive Achromats and Four Cell Mirror Symmetric Achromats, Proceedings of IPAC'10, Kyoto, Japan.

TUPPP093	General Results on the Nature of FEL Amplification	electron, FEL, laser, wiggler	1804
	S.D. Webb Tech-X, Boulder, Colorado, USA V. Litvinenko, G. Wang BNL, Upton, Long Island, New York, USA
	Free-electron lasers are increasingly important tools for the material and biological sciences, and although numerical and analytical theory is extensive, a fundamental question about the nature of the FEL growing modes has remained unanswered. In this proceeding, we present results of a topological nature concerning the number of amplifying solutions to the 1-dimensional FEL equations as related to the energy distribution of the electron bunches.

Paper

Title

Other Keywords

Page

MOOAA03

Fast Feedback Strategies for Longitudinal Beam Stabilization

feedback, controls, laser, electron

26

S. Pfeiffer, M.K. Bock, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
W. Jałmużna
TUL-DMCS, Łódź, Poland
G. Lichtenberg, H. Werner
TUHH, Hamburg, Germany

The key for pump-probe and seeding experiments at Free Electron Lasers such as FLASH is a femtosecond precise regulation of the bunch arrival time and compression. To maintain this beam based requirements, both for a single bunch and within a bunch train, it is necessary to combine field and beam based feedback loops. We present in this paper an advancement of the currently implemented beam based feedback system at FLASH. The principle of beam based modulation of the RF set point can be superimposed by a direct feedback loop with a beam optimized controller. Recent measurements of the achieved bunch arrival time jitter reduction to 20 fs have shown the performance gain by this direct feedback method *. The combination of both approaches will be presented and possible advantages are discussed.
* C. Schmidt et al., “Feedback Strategies for Bunch Arrival Time Stabilization at FLASH Towards 10 fs,” FEL’2011, Shanghai, August 2011, THPA26, http://www. JACoW.org.

Slides MOOAA03 [0.544 MB]

MOPPP085

Single Electron Dynamic of Microwave Undulator

electron, undulator, FEL, radiation

753

C. Chang, J. Neilson, C. Pellegrini, M. Shumail, S.G. Tantawi
SLAC, Menlo Park, California, USA

The analytical and numerical calculations for the dynamic of single electron and beam in RF undulator have been conducted and compared. The transverse and longitudinal velocity, trajectory, energy variation, and the spontaneous radiation are studied. It is found that the forward and backward wave (FW/BW) components have different contribution on electron motion and radiation, most of the energy spread comes from FW component, in other words, the effect of FW on modulating the electron energy is much stronger than that of BW for the same undulating-amplitude value, which mechanism has been analyzed.

MOPPR018

Beam Halo Monitor for FLASH and the European XFEL

electron, diagnostics, laser, pick-up

816

A. Ignatenko, N. Baboi, O. Hensler, M. Schmitz, K. Wittenburg
DESY, Hamburg, Germany
H.M. Henschel, W. Lange, W. Lohmann
DESY Zeuthen, Zeuthen, Germany
A. Ignatenko
BTU, Cottbus, Germany
S. Schuwalow
Uni HH, Hamburg, Germany

The Beam Halo Monitor for Free-electron Laser in Hamburg (FLASH) based on pCVD diamond and monocrystalline artificial sapphire sensors has been successfully commissioned in September 2009. It is a part of the beam dump diagnostics and ensures safe beam dumping. Its description and the experience gained during its operation are given. The ideas on the design and aspects of operation of the similar systems at FLASH II and the European XFEL are presented.

TUEPPB011

Echo Enabled High Mode Generation for X-ray FELs

laser, electron, bunching, FEL

1140

E. Hemsing
SLAC, Menlo Park, California, USA
A. Marinelli
UCLA, Los Angeles, California, USA

Funding: Work supported by U.S. DOE under Contract Nos. DE-AC02-76SF00515 and DE-FG02-07ER46272.
We describe a simple technique based on a modified echo-enabled harmonic generation (EEHG) scheme to manipulate the three-dimensional electron beam microbunching distribution in order to generate higher-order optical modes in an FEL. As with EEHG, the concept uses two modulators and two chicanes to produce microbunching. However, in one of the modulators, the resonant interaction with the laser has a well-defined transverse structure that becomes strongly correlated to the longitudinal microbunching distribution. Both high-harmonic frequencies and high transverse mode numbers can be generated through a transversely-dependent echo effect.

TUPPC009

Dihedral Group and Repetitive Achromats with Mirror Symmetric or Mirror Antisymmetric Basic Cell

multipole, electron, resonance, focusing

1170

V. Balandin, R. Brinkmann, W. Decking, N. Golubeva
DESY, Hamburg, Germany

Using the group-theoretical point of view for the design of magnetic optical achromats as introduced in*, we study in this paper second- and third-order repetitive achromats with a mirror symmetric or mirror antisymmetric basic cell. We also compare these achromats with repetitive achromats designed without internal cell symmetries taken into account.
* V.Balandin, R.Brinkmann, W.Decking, N.Golubeva. Two Cell Repetitive Achromats and Four Cell Mirror Symmetric Achromats, Proceedings of IPAC'10, Kyoto, Japan.

TUPPP093

General Results on the Nature of FEL Amplification

electron, FEL, laser, wiggler

1804

S.D. Webb
Tech-X, Boulder, Colorado, USA
V. Litvinenko, G. Wang
BNL, Upton, Long Island, New York, USA

Free-electron lasers are increasingly important tools for the material and biological sciences, and although numerical and analytical theory is extensive, a fundamental question about the nature of the FEL growing modes has remained unanswered. In this proceeding, we present results of a topological nature concerning the number of amplifying solutions to the 1-dimensional FEL equations as related to the energy distribution of the electron bunches.