IPAC2014 - List of Authors (Lehnert, U.)

Paper	Title	Page
MOPRI023	Simulation of the ELBE SRF Gun II	636
	P.N. Lu, A. Arnold, U. Lehnert, P. Murcek, J. Teichert, H. Vennekate, R. Xiang HZDR, Dresden, Germany
	Funding: EuCARD, contract number 227579 German Federal Ministry of Education and Research grant 05 ES4BR1/8 LA³NET, Grant Agreement Number GA-ITN-2011-289191 By combining the code of ASTRA and elegant in a user-friendly interface, a simulation tool is developed for the ELBE SRF Gun II. The photoelectric emission and first acceleration to several MeV in the gun cavity are simulated by ASTRA with a 1D Model, where the space charge effect is considered. The dependence of the beam quality on key parameters is studied, and a compromised optimization for a 77 pC beam is used for further elegant simulation of the beam transport through a dogleg and ELBE Linacs. Proper settings of the magnets and RF phases are the main targets of improving the beam quality. Up to now the best simulation result is an electron bunch with the energy of 47 MeV, energy spread of 66 keV, bunch length of 0.35 ps and transverse emittance of 1.9 μm and 2.7 μm in the two perpendicular directions.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI023
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TUZA02	THz Facility at ELBE: A Versatile Test Facility for Electron Bunch Diagnostics on Quasi-CW Electron Beams	933
	M. Gensch, B.W. Green, J. Hauser, S. Kovalev, M. Kuntzsch, U. Lehnert, P. Michel, R. Schurig HZDR, Dresden, Germany A. Al-Shemmary, V. B. Asgekar, T. Golz, H. Schlarb, N. Stojanovic, S. Vilcins DESY, Hamburg, Germany A.S. Fisher SLAC, Menlo Park, California, USA G. Geloni XFEL. EU, Hamburg, Germany A.-S. Müller, M. Schwarz KIT, Karlsruhe, Germany N.E. Neumann, D. Plettemeier TU Dresden, Dresden, Germany
	At the Helmholtz-Zentrum Dresden-Rossendorf near Dresden a quasi-cw low-energy electron linear accelerator based on superconducting radiofrequency technology is operated successfully for more than 10 years. The ELBE accelerator is driving several secondary radiation sources including 2 infrared free electron lasers. A new addition will be a THz facility that aims to make use of super-radiant THz radiation. In its final form the THz facility shall consist of one coherent diffraction radiator and one undulator source which provide high-field THz pulses at unprecedented repetition rates. While the medium term goal is to establish a unique user facility for nonlinear THz science, the THz sources are already used as a test facility for novel diagnostic techniques on quasi-cw electron beams. The progress of the developments is reported and an outlook into future challenges and opportunities is given.
	Slides TUZA02 [3.041 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUZA02
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TUPRO044	Bunch Compression of the Low-energy ELBE Electron Beam for Super-radiant THz Sources	1123
	U. Lehnert, P. Michel, R. Schurig HZDR, Dresden, Germany A.A. Aksoy Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey P.E. Evtushenko JLab, Newport News, Virginia, USA J.M. Krämer Danfysik A/S, Taastrup, Denmark
	At the ELBE radiation source two super-radiant THz sources, a broad-band trasnsition/diffraction radiation source and a planar undulator narrow-band sourc are under commissioning. At present the facility is driven from the ELBE linac with a CW electron beam of 100kHz repetition rate and up to 100pC of bunch charge. With the upgraded SRF electron gun bunch charges up to 1nC will become available. For the beam energies in the 20-30 MeV range buch compression into the sub-200 fs range becomes a major challenge. We present beam dynamics calculation of the attempted bunch compression scheme as well as first measurements obtained during the commissioning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO044
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WEPRO113	Status of the Radiation Source ELBE Upgrade	2233
	P. Michel, T.E. Cowan, U. Lehnert, U. Schramm HZDR, Dresden, Germany
	ELBE is based on a 40 MeV superconducting Electron Linac able to operate in CW mode and provides manifold secondary user beams. The suite of secondary beams include: two free electron lasers operating in the IR/THz regime; a fast neutron beam; a Bremsstrahlung gamma-ray beam; a low-energy positron beam; and patented single-electron test beams. The primary electron beam is also used for radiobiology research, or in interaction with ultra-intense PW-class lasers. Through 2014 ELBE will be upgraded to a Centre for High Power Radiation Sources. The ELBE beam current was increased to 1.6 mA by using novel solid state RF amplifiers. The concept also contains additional broad and narrow band coherent THz sources and the development of a 500 TW TiSa Laser and even a 1.5 PW diode pumped laser system. Laser plasma electron acceleration and proton acceleration experiments for medical applications are planned. Additionally, coupled electron laser beam experiments like Thomson scattering or injection of ELBE electron into the laser plasma will be done.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO113
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WEPME003	Two Years Experience with the Upgraded ELBE RF System Driven by 20kW Solid State Amplifier Blocks (SSPA)	2257
	H. Büttig, A. Arnold, A. Büchner, M. Justus, M. Kuntzsch, U. Lehnert, P. Michel, R. Schurig, G.S. Staats, J. Teichert HZDR, Dresden, Germany
	Since January 2012 the Superconducting CW Linac ELBE is equipped and in permanent operation with four 20 kW Solid State Amplifier Blocks. The poster gives an overview on the design of the new RF system and the experience gained within the first two years of operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME003
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THPRO012	Wakefield-based Dechirper Structures for ELBE	2882
	F. Reimann, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany U. Lehnert, P. Michel HZDR, Dresden, Germany
	Funding: Federal Ministry of Education and Research The efficient reduction of the pulse length and the energy width of electron beams plays a crucial role in the generation of short pulses in the range of sub-picoseconds at future light sources. At the radiation source ELBE in Dresden Rossendorf short pulses are required for coherent THz generation and laser-electron beam interaction experiments such as X-ray Thomson scattering. Energy dechirping can be carried out passively by wakefields generated when the electron beam passes through suitable structures, namely corrugated and dielectrically lined cylindrical pipes or dielectrically lined rectangular waveguides (,,*). All structures offer the possibility to tune the resulting wakefield and therefore the resulting energy chirp through a variation of purely geometrical or material parameters. In this paper we present a semi-analytical approach to determine the wakefield in dielectrically lined rectangular waveguide, starting with the expression of the electric field in terms of the structure's eigenmodes. Bane, Stupakov, SLAC-PUB-14925 (2012) Mosnier, Novokhatski, in: Proceedings of PAC97, Vancouver, Canada, 1997 * Antipov et al., in: Proceedings of IPAC2012, New Orleans, USA, 2012
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO012
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THPRO055	Electron Beam Final Focus System for Thomson Scattering at ELBE	2995
	J.M. Krämer, F. Bødker, A. Baurichter, M. Budde Danfysik A/S, Taastrup, Denmark A. Irman, U. Schramm Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany U. Lehnert, P. Michel HZDR, Dresden, Germany
	Funding: This work is part of LA3NET and funded by European Commission under Grant Agreement Number 289191. The design of an electron beam Final Focus System (FFS) aiming for high-flux laser-Thomson backscattering x-ray sources at ELBE* is presented. A telescope system consisting of four permanent magnet based quadrupoles was found to have significantly less chromatic aberrations than a quadrupole triplet. This allows sub-ps electron beam focusing to match the laser spot size at the interaction point. Focusing properties like the position of the focal plane and the spot size are retained for electron beam energies between 20 and 30 MeV by adjusting the position of the quadrupoles individually on a motorized stage. Since the electron beam is chirped for bunch compression upstream, the rms energy spread is increased to one or two percent and second order chromatic effects must be taken into account. For an emittance of 13 pi mm mrad, we predict rms spot sizes of about 40 um and divergences of about 15 mrad. We also present the design of the permanent magnet quadrupoles to be used for the FFS. Ferromagnetic poles ensure a high field quality and adjustable shunts allow for fine adjustment of the field strength and compensation of deviations in the permanent magnet material. *A. Jochmann et al., Phys. Rev. Lett. 111 (2013) 114803
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO055
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Paper

Title

Page

Simulation of the ELBE SRF Gun II

636

P.N. Lu, A. Arnold, U. Lehnert, P. Murcek, J. Teichert, H. Vennekate, R. Xiang
HZDR, Dresden, Germany

Funding: EuCARD, contract number 227579 German Federal Ministry of Education and Research grant 05 ES4BR1/8 LA³NET, Grant Agreement Number GA-ITN-2011-289191
By combining the code of ASTRA and elegant in a user-friendly interface, a simulation tool is developed for the ELBE SRF Gun II. The photoelectric emission and first acceleration to several MeV in the gun cavity are simulated by ASTRA with a 1D Model, where the space charge effect is considered. The dependence of the beam quality on key parameters is studied, and a compromised optimization for a 77 pC beam is used for further elegant simulation of the beam transport through a dogleg and ELBE Linacs. Proper settings of the magnets and RF phases are the main targets of improving the beam quality. Up to now the best simulation result is an electron bunch with the energy of 47 MeV, energy spread of 66 keV, bunch length of 0.35 ps and transverse emittance of 1.9 μm and 2.7 μm in the two perpendicular directions.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRI023

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TUZA02

THz Facility at ELBE: A Versatile Test Facility for Electron Bunch Diagnostics on Quasi-CW Electron Beams

933

M. Gensch, B.W. Green, J. Hauser, S. Kovalev, M. Kuntzsch, U. Lehnert, P. Michel, R. Schurig
HZDR, Dresden, Germany
A. Al-Shemmary, V. B. Asgekar, T. Golz, H. Schlarb, N. Stojanovic, S. Vilcins
DESY, Hamburg, Germany
A.S. Fisher
SLAC, Menlo Park, California, USA
G. Geloni
XFEL. EU, Hamburg, Germany
A.-S. Müller, M. Schwarz
KIT, Karlsruhe, Germany
N.E. Neumann, D. Plettemeier
TU Dresden, Dresden, Germany

At the Helmholtz-Zentrum Dresden-Rossendorf near Dresden a quasi-cw low-energy electron linear accelerator based on superconducting radiofrequency technology is operated successfully for more than 10 years. The ELBE accelerator is driving several secondary radiation sources including 2 infrared free electron lasers. A new addition will be a THz facility that aims to make use of super-radiant THz radiation. In its final form the THz facility shall consist of one coherent diffraction radiator and one undulator source which provide high-field THz pulses at unprecedented repetition rates. While the medium term goal is to establish a unique user facility for nonlinear THz science, the THz sources are already used as a test facility for novel diagnostic techniques on quasi-cw electron beams. The progress of the developments is reported and an outlook into future challenges and opportunities is given.

Slides TUZA02 [3.041 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUZA02

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TUPRO044

Bunch Compression of the Low-energy ELBE Electron Beam for Super-radiant THz Sources

1123

U. Lehnert, P. Michel, R. Schurig
HZDR, Dresden, Germany
A.A. Aksoy
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
P.E. Evtushenko
JLab, Newport News, Virginia, USA
J.M. Krämer
Danfysik A/S, Taastrup, Denmark

At the ELBE radiation source two super-radiant THz sources, a broad-band trasnsition/diffraction radiation source and a planar undulator narrow-band sourc are under commissioning. At present the facility is driven from the ELBE linac with a CW electron beam of 100kHz repetition rate and up to 100pC of bunch charge. With the upgraded SRF electron gun bunch charges up to 1nC will become available. For the beam energies in the 20-30 MeV range buch compression into the sub-200 fs range becomes a major challenge. We present beam dynamics calculation of the attempted bunch compression scheme as well as first measurements obtained during the commissioning.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-TUPRO044

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPRO113

Status of the Radiation Source ELBE Upgrade

2233

P. Michel, T.E. Cowan, U. Lehnert, U. Schramm
HZDR, Dresden, Germany

ELBE is based on a 40 MeV superconducting Electron Linac able to operate in CW mode and provides manifold secondary user beams. The suite of secondary beams include: two free electron lasers operating in the IR/THz regime; a fast neutron beam; a Bremsstrahlung gamma-ray beam; a low-energy positron beam; and patented single-electron test beams. The primary electron beam is also used for radiobiology research, or in interaction with ultra-intense PW-class lasers. Through 2014 ELBE will be upgraded to a Centre for High Power Radiation Sources. The ELBE beam current was increased to 1.6 mA by using novel solid state RF amplifiers. The concept also contains additional broad and narrow band coherent THz sources and the development of a 500 TW TiSa Laser and even a 1.5 PW diode pumped laser system. Laser plasma electron acceleration and proton acceleration experiments for medical applications are planned. Additionally, coupled electron laser beam experiments like Thomson scattering or injection of ELBE electron into the laser plasma will be done.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRO113

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WEPME003

Two Years Experience with the Upgraded ELBE RF System Driven by 20kW Solid State Amplifier Blocks (SSPA)

2257

H. Büttig, A. Arnold, A. Büchner, M. Justus, M. Kuntzsch, U. Lehnert, P. Michel, R. Schurig, G.S. Staats, J. Teichert
HZDR, Dresden, Germany

Since January 2012 the Superconducting CW Linac ELBE is equipped and in permanent operation with four 20 kW Solid State Amplifier Blocks. The poster gives an overview on the design of the new RF system and the experience gained within the first two years of operation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME003

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPRO012

Wakefield-based Dechirper Structures for ELBE

2882

F. Reimann, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
U. Lehnert, P. Michel
HZDR, Dresden, Germany

Funding: Federal Ministry of Education and Research
The efficient reduction of the pulse length and the energy width of electron beams plays a crucial role in the generation of short pulses in the range of sub-picoseconds at future light sources. At the radiation source ELBE in Dresden Rossendorf short pulses are required for coherent THz generation and laser-electron beam interaction experiments such as X-ray Thomson scattering. Energy dechirping can be carried out passively by wakefields generated when the electron beam passes through suitable structures, namely corrugated and dielectrically lined cylindrical pipes or dielectrically lined rectangular waveguides (*,**,***). All structures offer the possibility to tune the resulting wakefield and therefore the resulting energy chirp through a variation of purely geometrical or material parameters. In this paper we present a semi-analytical approach to determine the wakefield in dielectrically lined rectangular waveguide, starting with the expression of the electric field in terms of the structure's eigenmodes.
* Bane, Stupakov, SLAC-PUB-14925 (2012)
** Mosnier, Novokhatski, in: Proceedings of PAC97, Vancouver, Canada, 1997
*** Antipov et al., in: Proceedings of IPAC2012, New Orleans, USA, 2012

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO012

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THPRO055

Electron Beam Final Focus System for Thomson Scattering at ELBE

2995

J.M. Krämer, F. Bødker, A. Baurichter, M. Budde
Danfysik A/S, Taastrup, Denmark
A. Irman, U. Schramm
Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany
U. Lehnert, P. Michel
HZDR, Dresden, Germany

Funding: This work is part of LA3NET and funded by European Commission under Grant Agreement Number 289191.
The design of an electron beam Final Focus System (FFS) aiming for high-flux laser-Thomson backscattering x-ray sources at ELBE* is presented. A telescope system consisting of four permanent magnet based quadrupoles was found to have significantly less chromatic aberrations than a quadrupole triplet. This allows sub-ps electron beam focusing to match the laser spot size at the interaction point. Focusing properties like the position of the focal plane and the spot size are retained for electron beam energies between 20 and 30 MeV by adjusting the position of the quadrupoles individually on a motorized stage. Since the electron beam is chirped for bunch compression upstream, the rms energy spread is increased to one or two percent and second order chromatic effects must be taken into account. For an emittance of 13 pi mm mrad, we predict rms spot sizes of about 40 um and divergences of about 15 mrad. We also present the design of the permanent magnet quadrupoles to be used for the FFS. Ferromagnetic poles ensure a high field quality and adjustable shunts allow for fine adjustment of the field strength and compensation of deviations in the permanent magnet material.
*A. Jochmann et al., Phys. Rev. Lett. 111 (2013) 114803

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRO055

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)