IPAC2018 - List of Authors (Velez, A.V.)

Paper	Title	Page
WEPML047	Study on RF Coupler Kicks of SRF Cavities in the BESSY VSR Module	2804
	A.V. Tsakanian, T. Mertens Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany H.-W. Glock, J. Knobloch, M. Ries, A.V. Vélez HZB, Berlin, Germany
	The BESSY VSR upgrade of the BESSY II light source represents a novel approach to simultaneously store long (ca. 15ps) and short (ca. 1.7ps) bunches in the storage ring with the standard user optics. This challenging goal requires installation of four new SRF multi-cell cavities (2x1.5GHz and 2x1.75GHz) equipped with strong waveguide HOM dampers ensuring tolerable beam coupling impedance, necessary for stable operation. These cavities will operate at high 20MV/m in CW mode and at the zero-crossing phase according to the accelerating voltage. Consequently the transverse voltages will be maximum and can impact the transverse beam dynamics. The asymmetric character of those transverse kicks are caused by cavity fundamental power couplers (FPC) with strong monopole terms, introducing transverse kick to on-axis particles. Different FPC orientations were analyzed to optimize the net coupler kick from the four cavity chain. The coupler kick strength of each cavity is estimated taking into account accelerating mode amplitudes and phases required for operation in VSR mode.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML047
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPML048	HOM Power Levels in the BESSY VSR Cold String	2808
	A.V. Tsakanian, T. Flisgen Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany H.-W. Glock, J. Knobloch, A.V. Vélez HZB, Berlin, Germany
	The BESSY VSR upgrade of the BESSY II light source represents a novel approach to simultaneously store long (ca. 15ps) and short (ca. 1.7ps) bunches in the storage ring. This challenging goal requires installation of four new SRF cavities (2x1.5 GHz and 2x1.75 GHz) in one module for installation in a single straight. These cavities are equipped with strong waveguide HOM dampers necessary for stable operation. The expected HOM power and spectrum has been analyzed for the complete cold string. The cold string is a combination of various elements such as SRF cavities, bellows with and without shielding, warm HOM beampipe absorbers and UHV pumping domes. The presented study is performed for various BESSY VSR bunch filling patterns with 300 mA beam current. The contribution of each component to the total HOM power is presented. In addition the optimization of different cavity arrangements in the module is performed in order to reach the optimal operation conditions with equally distributed power levels along the string and tolerable beam coupling impedance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML048
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF033	Design of the Beamline Elements in the BESSY VSR Cold String	4123
	H.-W. Glock, F. Glöckner, J. Knobloch, E. Sharples, A.V. Tsakanian, A.V. Vélez HZB, Berlin, Germany T. Flisgen Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
	Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of the Helmholtz Association The four SRF cavities in the BESSY VSR module will be linked by bellows, which will be equipped with inner coaxial shielding pipes to prevent both parasitic fundamental mode losses and beam-induced heating. The central bellow will also act as a collimator for synchrotron radiation generated in the closest upstream dipole magnet. Additional bellows at the module's ends are needed to connect with the warm BESSY beam pipe. Outside the module the beam pipe cross section transitions will be located, which will be equipped with toroidal HOM absorbing elements. In the paper the recent design considerations and specifications for all those components will be described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF033
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPMF038	Status of the BESSY VSR Project	4138
	P. Schnizer, W. Anders, Y. Bergmann, P. Goslawski, H. Hartmut, A. Jankowiak, J. Knobloch, A. Neumann, K. Ott, M. Ries, A. Schälicke, A.V. Vélez HZB, Berlin, Germany
	BESSY VSR is set out to provide a variable pulse pattern to the BESSY II users. This project is now fully funded and heading into its implementation phase. The pulse pattern, consisting of long and short pulses, require inserting cavities providing a 3rd and a 3.5th harmonic of the fundamental harmonic of the ring. Therefore 1.5 and 1.75 GHz cavities are developed with appropriate higher order mode damping spectrum. Similarly the BESSY II ring and injector chain has to be upgraded to provide appropriate diagnostics and increase the injection efficiency. In this paper we give the current status of the project and give an overview of scientific challenges currently being tackled.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF038
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Study on RF Coupler Kicks of SRF Cavities in the BESSY VSR Module

2804

A.V. Tsakanian, T. Mertens
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
H.-W. Glock, J. Knobloch, M. Ries, A.V. Vélez
HZB, Berlin, Germany

The BESSY VSR upgrade of the BESSY II light source represents a novel approach to simultaneously store long (ca. 15ps) and short (ca. 1.7ps) bunches in the storage ring with the standard user optics. This challenging goal requires installation of four new SRF multi-cell cavities (2x1.5GHz and 2x1.75GHz) equipped with strong waveguide HOM dampers ensuring tolerable beam coupling impedance, necessary for stable operation. These cavities will operate at high 20MV/m in CW mode and at the zero-crossing phase according to the accelerating voltage. Consequently the transverse voltages will be maximum and can impact the transverse beam dynamics. The asymmetric character of those transverse kicks are caused by cavity fundamental power couplers (FPC) with strong monopole terms, introducing transverse kick to on-axis particles. Different FPC orientations were analyzed to optimize the net coupler kick from the four cavity chain. The coupler kick strength of each cavity is estimated taking into account accelerating mode amplitudes and phases required for operation in VSR mode.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML047

Export •

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

WEPML048

HOM Power Levels in the BESSY VSR Cold String

2808

A.V. Tsakanian, T. Flisgen
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
H.-W. Glock, J. Knobloch, A.V. Vélez
HZB, Berlin, Germany

The BESSY VSR upgrade of the BESSY II light source represents a novel approach to simultaneously store long (ca. 15ps) and short (ca. 1.7ps) bunches in the storage ring. This challenging goal requires installation of four new SRF cavities (2x1.5 GHz and 2x1.75 GHz) in one module for installation in a single straight. These cavities are equipped with strong waveguide HOM dampers necessary for stable operation. The expected HOM power and spectrum has been analyzed for the complete cold string. The cold string is a combination of various elements such as SRF cavities, bellows with and without shielding, warm HOM beampipe absorbers and UHV pumping domes. The presented study is performed for various BESSY VSR bunch filling patterns with 300 mA beam current. The contribution of each component to the total HOM power is presented. In addition the optimization of different cavity arrangements in the module is performed in order to reach the optimal operation conditions with equally distributed power levels along the string and tolerable beam coupling impedance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML048

Export •

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

THPMF033

Design of the Beamline Elements in the BESSY VSR Cold String

4123

H.-W. Glock, F. Glöckner, J. Knobloch, E. Sharples, A.V. Tsakanian, A.V. Vélez
HZB, Berlin, Germany
T. Flisgen
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany

Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of the Helmholtz Association
The four SRF cavities in the BESSY VSR module will be linked by bellows, which will be equipped with inner coaxial shielding pipes to prevent both parasitic fundamental mode losses and beam-induced heating. The central bellow will also act as a collimator for synchrotron radiation generated in the closest upstream dipole magnet. Additional bellows at the module's ends are needed to connect with the warm BESSY beam pipe. Outside the module the beam pipe cross section transitions will be located, which will be equipped with toroidal HOM absorbing elements. In the paper the recent design considerations and specifications for all those components will be described.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF033

Export •

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

THPMF038

Status of the BESSY VSR Project

4138

P. Schnizer, W. Anders, Y. Bergmann, P. Goslawski, H. Hartmut, A. Jankowiak, J. Knobloch, A. Neumann, K. Ott, M. Ries, A. Schälicke, A.V. Vélez
HZB, Berlin, Germany

BESSY VSR is set out to provide a variable pulse pattern to the BESSY II users. This project is now fully funded and heading into its implementation phase. The pulse pattern, consisting of long and short pulses, require inserting cavities providing a 3rd and a 3.5th harmonic of the fundamental harmonic of the ring. Therefore 1.5 and 1.75 GHz cavities are developed with appropriate higher order mode damping spectrum. Similarly the BESSY II ring and injector chain has to be upgraded to provide appropriate diagnostics and increase the injection efficiency. In this paper we give the current status of the project and give an overview of scientific challenges currently being tackled.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF038

Export •

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