IPAC2018 - List of Authors (Riemann, B.)

Paper	Title	Page
MOPMK014	Resistive-Wall Impedance of Insertions for FCC-hh	378
	B. Riemann, S. Khan DELTA, Dortmund, Germany S. Arsenyev, D. Schulte CERN, Geneva, Switzerland
	Funding: This work is supported by the German Ministry of Education & Research (BMBF, funding code 05P15PERB1) and CERN (reference numbers KE3123, EDMS 1606722). In this work, transverse and longitudinal resistive-wall impedances for beam pipes in the experiment, injection, extraction and RF systems insertion regions of the Future Hadron-Hadron Collider (FCC-hh) are computed based on contributions from different given cross sections of the surrounding (elliptical) chamber parts along the beam path, their temperature-dependent conductivities, and optical functions. An emphasis is placed on the behaviour of transverse impedance in the main experimental regions (A and G), where maximum beta values of 10⁴ to 10⁵ m occur in dependence of the operation mode respectively lattice configuration. Main contributions to the transverse and longitudinal impedance budget are identified, and possibilities of reducing them are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK014
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THPAK113	Cavity Characterization Studies With the Latest Revision of YACS	3503
	B.D. Isbarn, S. Koetter, B. Riemann, M. Sommer, T. Weis DELTA, Dortmund, Germany
	Funding: Work supported by the BMBF under contract no. 05K13PEB. YACS is a 2.5D finite element method solver capable of solving for the full 3D eigenfrequency spectra of resonant axisymmetric structures while reducing the computational problem to a 2D rotation plane. The most recent revision of YACS now supports arbitrary order basis functions for the geometry and field discretization. In earlier revisions of YACS spurious modes were introduced by increasing the order of either the geometry or field basis functions. To prevent the emergence of spurious modes, YACS now matches the function spaces of the in-plane and out-plane function basis, and thus yields spurious free solutions. To demonstrate the capabilities of YACS, extensive cavity characterization studies on curved multicell microwave cavities are presented. Due to the combined utilization of the rotation symmetry, higher order basis functions and curved elements, eigenfrequency spectra above 10 GHz for L-band multicell structures can be easily obtained.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK113
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THPAK115	Numerical Multiparticle Tracking Studies on Coupled-Bunch Instabilities in the Presence of RF Phase Modulation	3511
	M. Sommer, B.D. Isbarn, S. Koetter, B. Riemann, T. Weis DELTA, Dortmund, Germany
	Funding: Work supported by the BMBF under contract no. 05K13PEB. Since 2008, longitudinal coupled-bunch instabilities are suppressed at DELTA by a modulation of the phase of the accelerating RF field inside the cavity. To achieve a deeper understanding of the interaction of both effects, experimental studies have been made in 2016. These studies show a quadratic dependency of the coupled-bunch mode damping rates on the phase modulation amplitude. Recently, a numerical particle tracking code has been developed to confirm the experimental results. It is based on long range wake field effects produced inside an RF cavity acting on multi particle bunches of arbitrary charge, together with phase focusing by a phase modulated accelerating field. The numerical results confirm the quadratic dependency of damping rates on the phase shift obtained in experimental studies before.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK115
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THPMK098	A Tunable Narrowband Source in the Sub-THz and THz Range at DELTA	4534
	C. Mai, B. Büsing, S. Khan, A. Meyer auf der Heide, B. Riemann, B. Sawadski, P. Ungelenk DELTA, Dortmund, Germany M. Brosi, J.L. Steinmann KIT, Karlsruhe, Germany F. Frei PSI, Villigen PSI, Switzerland C. Gerth DESY, Hamburg, Germany M. Laabs, N. Neumann TU Dresden, Dresden, Germany N.M. Lockmann University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	Funding: Work supported by the DFG (INST 212/236-1 FUGG), the BMBF (05K13PEC, 05K16PEB) and the state of NRW. At DELTA, a 1.5-GeV electron storage ring operated as a synchrotron light source by the TU Dortmund University, an interaction of ultrashort laser pulses with electron bunches is used to generate broadband as well as tunable narrowband radiation in the frequency range between 75 GHz and 5.6 THz. The performance of the source was studied using two different Fourier-transform spectrometers. It was demonstrated that the source can be used for the characterization and comparison of Schottky-diode based detectors, e.g., an on-chip spectrometer enabling single-shot applications.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK098
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THPMK099	Measurement of the Laser-Induced Energy Modulation Amplitude at the Short-Pulse Facility at DELTA	4538
	A. Meyer auf der Heide, B. Büsing, S. Khan, N.M. Lockmann, C. Mai, B. Riemann, B. Sawadski DELTA, Dortmund, Germany
	The short-pulse facility at the synchrotron light source DELTA operated by the TU Dortmund University employs coherent harmonic generation (CHG) to provide ultrashort pulses in the vacuum ultraviolet and terahertz regime. Here, a laser-electron interaction results in a modulation of the electron energy which is transformed into a density modulation by a magnetic chicane. Measurements of the energy modulation amplitude with different techniques including an RF phase modulation are presented. A combination of the results allow to estimate the energy spread of the electron beam.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK099
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THPML084	Validating the COBEA Algorithm at the DELTA Storage Ring	4851
	B. Riemann, B.D. Isbarn, S. Khan, S. Koetter, T. Weis DELTA, Dortmund, Germany
	Closed-Orbit Bilinear-Exponential Analysis (COBEA) is an algorithm to decompose monitor-corrector response matrices into (scaled) beta optics values, phase advances, scaled dispersion and betatron tunes. No explicit magnetic lattice model is required for COBEA - only the sequence of monitors and correctors along the beam path (no lengths, no strengths approach). To obtain absolute beta values, the length of one drift space can be provided as optional input. In this work, the application of COBEA to the DELTA storage ring, operated by TU Dortmund University, is discussed, and its results for betatron tunes and scaled dispersion are compared with those of conventional, direct measurement methods. COBEA is also put in a historical perspective to other diagnostic algorithms. Improvements in the Python implementation of COBEA, which is available as free software, are presented. Due to COBEA being relatively modest regarding its requirements on input data respectively hardware, it should be applicable to the majority of existing storage rings.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML084
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Paper

Title

Page

Resistive-Wall Impedance of Insertions for FCC-hh

378

B. Riemann, S. Khan
DELTA, Dortmund, Germany
S. Arsenyev, D. Schulte
CERN, Geneva, Switzerland

Funding: This work is supported by the German Ministry of Education & Research (BMBF, funding code 05P15PERB1) and CERN (reference numbers KE3123, EDMS 1606722).
In this work, transverse and longitudinal resistive-wall impedances for beam pipes in the experiment, injection, extraction and RF systems insertion regions of the Future Hadron-Hadron Collider (FCC-hh) are computed based on contributions from different given cross sections of the surrounding (elliptical) chamber parts along the beam path, their temperature-dependent conductivities, and optical functions. An emphasis is placed on the behaviour of transverse impedance in the main experimental regions (A and G), where maximum beta values of 10⁴ to 10⁵ m occur in dependence of the operation mode respectively lattice configuration. Main contributions to the transverse and longitudinal impedance budget are identified, and possibilities of reducing them are discussed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK014

Export •

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

THPAK113

Cavity Characterization Studies With the Latest Revision of YACS

3503

B.D. Isbarn, S. Koetter, B. Riemann, M. Sommer, T. Weis
DELTA, Dortmund, Germany

Funding: Work supported by the BMBF under contract no. 05K13PEB.
YACS is a 2.5D finite element method solver capable of solving for the full 3D eigenfrequency spectra of resonant axisymmetric structures while reducing the computational problem to a 2D rotation plane. The most recent revision of YACS now supports arbitrary order basis functions for the geometry and field discretization. In earlier revisions of YACS spurious modes were introduced by increasing the order of either the geometry or field basis functions. To prevent the emergence of spurious modes, YACS now matches the function spaces of the in-plane and out-plane function basis, and thus yields spurious free solutions. To demonstrate the capabilities of YACS, extensive cavity characterization studies on curved multicell microwave cavities are presented. Due to the combined utilization of the rotation symmetry, higher order basis functions and curved elements, eigenfrequency spectra above 10 GHz for L-band multicell structures can be easily obtained.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK113

Export •

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

THPAK115

Numerical Multiparticle Tracking Studies on Coupled-Bunch Instabilities in the Presence of RF Phase Modulation

3511

M. Sommer, B.D. Isbarn, S. Koetter, B. Riemann, T. Weis
DELTA, Dortmund, Germany

Funding: Work supported by the BMBF under contract no. 05K13PEB.
Since 2008, longitudinal coupled-bunch instabilities are suppressed at DELTA by a modulation of the phase of the accelerating RF field inside the cavity. To achieve a deeper understanding of the interaction of both effects, experimental studies have been made in 2016. These studies show a quadratic dependency of the coupled-bunch mode damping rates on the phase modulation amplitude. Recently, a numerical particle tracking code has been developed to confirm the experimental results. It is based on long range wake field effects produced inside an RF cavity acting on multi particle bunches of arbitrary charge, together with phase focusing by a phase modulated accelerating field. The numerical results confirm the quadratic dependency of damping rates on the phase shift obtained in experimental studies before.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK115

Export •

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

THPMK098

A Tunable Narrowband Source in the Sub-THz and THz Range at DELTA

4534

C. Mai, B. Büsing, S. Khan, A. Meyer auf der Heide, B. Riemann, B. Sawadski, P. Ungelenk
DELTA, Dortmund, Germany
M. Brosi, J.L. Steinmann
KIT, Karlsruhe, Germany
F. Frei
PSI, Villigen PSI, Switzerland
C. Gerth
DESY, Hamburg, Germany
M. Laabs, N. Neumann
TU Dresden, Dresden, Germany
N.M. Lockmann
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Funding: Work supported by the DFG (INST 212/236-1 FUGG), the BMBF (05K13PEC, 05K16PEB) and the state of NRW.
At DELTA, a 1.5-GeV electron storage ring operated as a synchrotron light source by the TU Dortmund University, an interaction of ultrashort laser pulses with electron bunches is used to generate broadband as well as tunable narrowband radiation in the frequency range between 75 GHz and 5.6 THz. The performance of the source was studied using two different Fourier-transform spectrometers. It was demonstrated that the source can be used for the characterization and comparison of Schottky-diode based detectors, e.g., an on-chip spectrometer enabling single-shot applications.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK098

Export •

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

THPMK099

Measurement of the Laser-Induced Energy Modulation Amplitude at the Short-Pulse Facility at DELTA

4538

A. Meyer auf der Heide, B. Büsing, S. Khan, N.M. Lockmann, C. Mai, B. Riemann, B. Sawadski
DELTA, Dortmund, Germany

The short-pulse facility at the synchrotron light source DELTA operated by the TU Dortmund University employs coherent harmonic generation (CHG) to provide ultrashort pulses in the vacuum ultraviolet and terahertz regime. Here, a laser-electron interaction results in a modulation of the electron energy which is transformed into a density modulation by a magnetic chicane. Measurements of the energy modulation amplitude with different techniques including an RF phase modulation are presented. A combination of the results allow to estimate the energy spread of the electron beam.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK099

Export •

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

THPML084

Validating the COBEA Algorithm at the DELTA Storage Ring

4851

B. Riemann, B.D. Isbarn, S. Khan, S. Koetter, T. Weis
DELTA, Dortmund, Germany

Closed-Orbit Bilinear-Exponential Analysis (COBEA) is an algorithm to decompose monitor-corrector response matrices into (scaled) beta optics values, phase advances, scaled dispersion and betatron tunes. No explicit magnetic lattice model is required for COBEA - only the sequence of monitors and correctors along the beam path (no lengths, no strengths approach). To obtain absolute beta values, the length of one drift space can be provided as optional input. In this work, the application of COBEA to the DELTA storage ring, operated by TU Dortmund University, is discussed, and its results for betatron tunes and scaled dispersion are compared with those of conventional, direct measurement methods. COBEA is also put in a historical perspective to other diagnostic algorithms. Improvements in the Python implementation of COBEA, which is available as free software, are presented. Due to COBEA being relatively modest regarding its requirements on input data respectively hardware, it should be applicable to the majority of existing storage rings.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML084

Export •

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