IPAC2015 - List of Authors (Ries, M.)

Paper	Title	Page
MOPWA019	Status of the Robinson Wiggler Project at the Metrology Light Source	132
	T. Goetsch, J. Feikes, M. Ries, G. Wüstefeld HZB, Berlin, Germany
	The beam lifetime in electron storage rings concerns machines running in decay mode as well as machines doing top-up. A standard procedure to increase the lifetime is via bunch lengthening as the lifetime depends on the electron density in the bunch. Bunch lengthening is typically achieved with higher harmonic (Landau) cavities. As noted in , there are several advantages in using a different approach: it is possible to increase the bunch length by installing a Transverse Gradient (Robinson) Wiggler, which allows to transfer damping between the horizontal and the longitudinal plane. While increasing the bunch length, the horizontal emittance is being reduced yielding advantages regarding the source size depending on the magnet optics. At the Metrology Light Source, a primary source standard used by Germanys national metrology institute (Physikalisch-Technische Bundesanstalt), such a scheme is being investigated. The current state of the project including dynamic aperture effects and synchrotron radiation issues of the device is being presented in the following. T. Goetsch et al.,WEPRO028 in Proceedings of IPAC2014, Dresden (Germany), 2014 ** R. Klein et al., Phys. Rev. ST-AB 11, 110701, 2008
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MOPWA021	Transverse Resonance Island Buckets at the MLS and BESSY II	138
	M. Ries, J. Feikes, T. Goetsch, P. Goslawski, J. Li, M. Ruprecht, A. Schälicke, G. Wüstefeld HZB, Berlin, Germany
	By operating the Metrology Light Source (MLS) near horizontal resonances (fx/frev=1/2, 1/3 or 1/4), two, three or four resonance island buckets may be populated for beam storage. This paper presents experimental results and operational experience such as tuning the machine for high current, controlling inter-bucket diffusion rates, improving overall lifetime and extraction of radiation pulses with sub-revolution repetition rate. First approaches to transfer this mode of operation to the BESSY II storage ring will also be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA021
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MOPWA022	Influence of Transient Beam Loading on the Longitudinal Beam Dynamics at BESSY VSR	141
	M. Ruprecht, P. Goslawski, A. Jankowiak, A. Neumann, M. Ries, G. Wüstefeld HZB, Berlin, Germany T. Weis DELTA, Dortmund, Germany
	BESSY VSR, a scheme where 1.7 ps and 15 ps long bunches (rms) can be stored simultaneously in the BESSY II storage ring has recently been proposed . The strong longitudinal bunch focusing is achieved by superconducting high gradient RF cavities. If the bunch fill pattern exhibits a significant inhomogeneity, e.g. due to gaps, transient beam loading causes a distortion of the longitudinal phase space which is different for each bunch. The result are variations along the fill pattern in synchronous phase, synchrotron frequency and bunch shape. This paper presents investigations of transient beam loading and depicts the consequences on bunch length, phase stability and longitudinal multi-bunch oscillations for the projected setup of BESSY VSR. G. Wüstefeld, A. Jankowiak, J. Knobloch, M. Ries, Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring, Proceedings of IPAC2011, San Sebastián, Spain
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA022
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MOPHA010	RF Feedback and Detuning Studies for the BESSY Variable Pulse Length Storage Ring Higher Harmonic SC Cavities	798
	A. Neumann, P. Echevarria, P. Goslawski, M. Ries, M. Ruprecht, A.V. Vélez, G. Wüstefeld HZB, Berlin, Germany
	For the feasibility of the BESSY VSR upgrade project of BESSY II two higher harmonic systems at a factor of 3 and 3.5 of the ring's RF fundamental of 500 MHz will be installed in the ring. Operating in continuous wave at high average accelerating field of 20 MV/m and phased at zero-crossing, the superconducting cavities have to be detuned within tight margins to ensure stable operation and low power consumption at a loaded Q of 5·10⁷. The field variation of the cavities is mainly driven by the repetitive transient beam-loading of the envisaged complex bunch fill pattern in the ring. Within this work combined LLRF-cavity and longitudinal beam dynamics simulation will demonstrate the limits for stable operation, especially the coupling between synchrotron oscillation and RF feedback settings. Further impact by beam current decay and top-up injection shots are being simulated. * G. Wüstefeld et al., IPAC 11, San Sebastiàn, Spain, p. 2936.
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Paper

Title

Page

Status of the Robinson Wiggler Project at the Metrology Light Source

132

T. Goetsch, J. Feikes, M. Ries, G. Wüstefeld
HZB, Berlin, Germany

The beam lifetime in electron storage rings concerns machines running in decay mode as well as machines doing top-up. A standard procedure to increase the lifetime is via bunch lengthening as the lifetime depends on the electron density in the bunch. Bunch lengthening is typically achieved with higher harmonic (Landau) cavities. As noted in *, there are several advantages in using a different approach: it is possible to increase the bunch length by installing a Transverse Gradient (Robinson) Wiggler, which allows to transfer damping between the horizontal and the longitudinal plane. While increasing the bunch length, the horizontal emittance is being reduced yielding advantages regarding the source size depending on the magnet optics. At the Metrology Light Source, a primary source standard used by Germanys national metrology institute (Physikalisch-Technische Bundesanstalt)**, such a scheme is being investigated. The current state of the project including dynamic aperture effects and synchrotron radiation issues of the device is being presented in the following.
* T. Goetsch et al.,WEPRO028 in Proceedings of IPAC2014, Dresden (Germany), 2014
** R. Klein et al., Phys. Rev. ST-AB 11, 110701, 2008

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA019

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

MOPWA021

Transverse Resonance Island Buckets at the MLS and BESSY II

138

M. Ries, J. Feikes, T. Goetsch, P. Goslawski, J. Li, M. Ruprecht, A. Schälicke, G. Wüstefeld
HZB, Berlin, Germany

By operating the Metrology Light Source (MLS) near horizontal resonances (fx/frev=1/2, 1/3 or 1/4), two, three or four resonance island buckets may be populated for beam storage. This paper presents experimental results and operational experience such as tuning the machine for high current, controlling inter-bucket diffusion rates, improving overall lifetime and extraction of radiation pulses with sub-revolution repetition rate. First approaches to transfer this mode of operation to the BESSY II storage ring will also be presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA021

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

MOPWA022

Influence of Transient Beam Loading on the Longitudinal Beam Dynamics at BESSY VSR

141

M. Ruprecht, P. Goslawski, A. Jankowiak, A. Neumann, M. Ries, G. Wüstefeld
HZB, Berlin, Germany
T. Weis
DELTA, Dortmund, Germany

BESSY VSR, a scheme where 1.7 ps and 15 ps long bunches (rms) can be stored simultaneously in the BESSY II storage ring has recently been proposed *. The strong longitudinal bunch focusing is achieved by superconducting high gradient RF cavities. If the bunch fill pattern exhibits a significant inhomogeneity, e.g. due to gaps, transient beam loading causes a distortion of the longitudinal phase space which is different for each bunch. The result are variations along the fill pattern in synchronous phase, synchrotron frequency and bunch shape. This paper presents investigations of transient beam loading and depicts the consequences on bunch length, phase stability and longitudinal multi-bunch oscillations for the projected setup of BESSY VSR.
* G. Wüstefeld, A. Jankowiak, J. Knobloch, M. Ries, Simultaneous Long and Short Electron Bunches in the BESSY II Storage Ring, Proceedings of IPAC2011, San Sebastián, Spain

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA022

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

MOPHA010

RF Feedback and Detuning Studies for the BESSY Variable Pulse Length Storage Ring Higher Harmonic SC Cavities

798

A. Neumann, P. Echevarria, P. Goslawski, M. Ries, M. Ruprecht, A.V. Vélez, G. Wüstefeld
HZB, Berlin, Germany

For the feasibility of the BESSY VSR upgrade project of BESSY II two higher harmonic systems at a factor of 3 and 3.5 of the ring's RF fundamental of 500 MHz will be installed in the ring. Operating in continuous wave at high average accelerating field of 20 MV/m and phased at zero-crossing, the superconducting cavities have to be detuned within tight margins to ensure stable operation and low power consumption at a loaded Q of 5·10⁷. The field variation of the cavities is mainly driven by the repetitive transient beam-loading of the envisaged complex bunch fill pattern in the ring. Within this work combined LLRF-cavity and longitudinal beam dynamics simulation will demonstrate the limits for stable operation, especially the coupling between synchrotron oscillation and RF feedback settings. Further impact by beam current decay and top-up injection shots are being simulated.
* G. Wüstefeld et al., IPAC 11, San Sebastiàn, Spain, p. 2936.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA010

Export •

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