| Paper | Title | Page |
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| MOPOPT018 | Advancing to a GHz Transition Radiation Monitor for Longitudinal Charge Distribution Measurements | 267 |
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Funding: This work is supported by the German Federal Ministry of Education and Research (BMBF) under contract no. 05P21RORB2. Joint Project 05P2021 - R&D Accelerator (DIAGNOSE) In the past, longitudinal beam profiles have been measured with e.g., Feschenko monitors*, Fast Faraday Cups (FFC)** and field monitors. Feschenko monitors usually examine an average shape over several pulses and FFCs are interceptive devices by design. In this work we want to present the progress in the development of a novel GHz diffraction radiation monitor which shall be able to measure the longitudinal charge distribution of single bunches within Hadron beam LINACS non-destructively. A proof-of-concept measurement has been performed at GSI. We aim for a resolution of 50 to 100ps at beam energies of β=0.05 to 0.74. electronic field simulations were performed using CST Particle Studio to determine an optimal RF-Window, which also suits as vacuum chamber and the beam energy and angular dependencies of the diffraction radiation for different materials were analyzed. * A. V. Feschenko (2001): Methods and Instrumentation for Bunch Shape Measurements. In Proc. PAC’01, paper ROAB002 ** G. Zhu et al (2018): Rev. Sci. Instrum. issn 0034-6748, doi :10.1063/1.5027608 |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT018 | |
| About • | Received ※ 14 June 2022 — Revised ※ 11 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 15 June 2022 | |
| Cite • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
| MOPOPT019 | Wakefield Studies for a Bunch Arrival-Time Monitor Concept with Rod-Shaped Pickups on a Printed Circuit Board for X-Ray Free-Electron Lasers | 271 |
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Funding: This work is supported by the German Federal Ministry of Education and Research (BMBF) under contract No. 05K19RO1. The European XFEL (EuXFEL) and other notable X-ray Free-Electron Laser facilities rely on an all-optical synchronization system with electro-optical bunch arrival-time monitors (BAM). The current BAMs were benchmarked with a resolution of 3.5 fs for nominal 250 pC bunches at the EuXFEL, including jitter of the optical reference system. The arrival-time jitter could be reduced to about 10 fs with a beam-based feedback system. For future experiments at the EuXFEL the bunch charge will be decreased to a level where the existing system’s accuracy will no longer be sufficient. In simulations a concept based on rod-shaped pickups mounted on a printed circuit board indicated its potential for such low charge applications. For the feasibility of the proposed design, its contribution to the total impedance is essential. In this work the design and an intermediate version are compared to state-of-the-art BAM regarding their wake potential. Furthermore, measures to mitigate wakefields are discussed. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-MOPOPT019 | |
| About • | Received ※ 08 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 05 July 2022 | |
| Cite • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |
| TUPOTK005 | Mitigation of Parasitic Losses in the Quadrupole Resonator Enabling Direct Measurements of Low Residual Resistances of SRF Samples | 1196 |
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| The quadrupole resonator (QPR) is a dedicated sample-test cavity for the RF characterization of superconducting samples in a wide temperature, RF field and frequency range. Its main purpose are high resolution measurements of the surface resistance with direct access to the residual resistance thanks to the low frequency of the first operating quadrupole mode. Besides the well-known high resolution of the QPR, a bias of measurement data towards higher values has been observed, especially at higher harmonic quadrupole modes. Numerical studies show that this can be explained by parasitic RF losses on the adapter flange used to mount samples into the QPR. Coating several micrometer of niobium on those surfaces of the stainless steel flange that are exposed to the RF fields significantly reduced this bias, enabling a direct measurement of a residual resistance smaller than 5 nano-Ohm at 2 K and 413 MHz. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2022-TUPOTK005 | |
| About • | Received ※ 08 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 28 June 2022 | |
| Cite • | reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml) | |