LINAC2022 - Classification: Technology / Room temperature RF

Paper	Title	Page
MOPORI20	Fabrication, Field Measurement, and Testing of a Compact RF Deflecting Cavity for ELBE	271
	T.G. Hallilingaiah, P. Michel, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany A. Arnold, S. Köppen, P. Michel HZDR, Dresden, Germany U. van Rienen University of Rostock, Rostock, Germany
	A transverse deflecting cavity is being developed for the electron linac ELBE to separate the bunches into two or more beamlines so that multiple user experiments can be carried out simultaneously. A normal conducting double quarter-wave cavity has been designed to deliver a transverse kick of 300 kV when driven by an 800 W solid-state amplifier at 273 MHz. The main challenges in fabrication were machining the complex cavity parts with high precision, pre-tuning the cavity frequency, and the final vacuum brazing within the tolerances, which are described in this paper. The reason for a low intrinsic quality factor measured during the low power test was investigated, and suitable steps were taken to improve the quality factor. The cavity field profiles obtained from the bead-pull measurement matched the simulation results. Further, the cavity was driven up to 1 kW using a modified pick-up antenna, and eventually, vacuum conditioning of the cavity was accomplished. The cavity fulfils the design requirements and is ready for beam tests.
	Poster MOPORI20 [4.325 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPORI20
About •	Received ※ 14 August 2022 — Revised ※ 15 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 07 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPORI22	High-Power Test of an APF IH-DTL Prototype for the Muon Linac	275
SUPCRI07	use link to see paper's listing under its alternate paper code
	Y. Nakazawa, H. Iinuma Ibaraki University, Ibaraki, Japan E. Cicek, H. Ego, K. Futatsukawa, N. Kawamura, T. Mibe, S. Mizobata, N. Saito, M. Yoshida KEK, Ibaraki, Japan N. Hayashizaki Research Laboratory for Nuclear Research, Tokyo Institute of Technology, Tokyo, Japan Y. Iwata NIRS, Chiba-shi, Japan R. Kitamura, Y. Kondo, T. Morishita JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan M. Otani J-PARC, KEK & JAEA, Ibaraki-ken, Japan Y. Sue, K. Sumi, M. Yotsuzuka Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan Y. Takeuchi Kyushu University, Fukuoka, Japan T. Yamazaki KEK, Tokai Branch, Tokai, Naka, Ibaraki, Japan H.Y. Yasuda University of Tokyo, Tokyo, Japan
	A muon linac is under development for a new muon g-2/EDM experiment at J-PARC. The muons are cooled to about room temperature and then re-accelerated to 212 MeV by four linear accelerators to produce a low-emittance muon beam. In the low-beta section, a short-range acceleration cavity with high efficiency needs to be developed to suppress the decay of muons. We propose a 324 MHz inter-digital H-mode drift-tube linac (IH-DTL) with high acceleration efficiency. The cavity can be downsized by introducing the alternating phase focusing (APF) method that provides transverse focusing only with an E-field. We have developed a prototype cavity that accelerates muons up to 1.3 MeV to demonstrate the principle. In this paper, the result of the high power test of the APF IH-DTL prototype is reported.
	Poster MOPORI22 [10.978 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPORI22
About •	Received ※ 13 August 2022 — Revised ※ 16 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 01 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPORI23	High-Power Testing Results of X-Band RF-Window and 45 Degrees Spiral Load	279
	M. Boronat, H. Bursali, N. Catalán Lasheras, A. Grudiev, G. McMonagle, I. Syratchev CERN, Meyrin, Switzerland
	The X-Band test facilities at CERN have been running for some years now qualifying CLIC structure prototypes but also developing and testing high power general-purpose X-Band components, used in a wide range of applications. Driven by operational needs, several components have been redesigned and tested aiming to optimize the reliability and the compactness of the full system and therefore enhancing the accessibility of this technology inside and outside CERN. To this extent, a new high-power RF-window has been designed and tested aiming to avoid unnecessary venting of high-power sections already conditioned, easing the interventions, and protecting the klystrons. A new spiral load prototype has also been designed, built, and tested, optimizing the compactness, and improving the fabrication process. In these pages, the design and manufacturing for each component will be shortly described, along with the last results on the high-power testing.
	Poster MOPORI23 [2.275 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPORI23
About •	Received ※ 24 August 2022 — Revised ※ 29 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 31 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPORI24	Monte Carlo Model of High-Voltage Conditioning and Operation	283
	W.L. Millar, W. Wuensch CERN, Meyrin, Switzerland G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	To synthesise the experimental results and theory pertaining to high-field phenomena, a model has been developed to simulate the conditioning and operation of high-field systems. By using a mesh-based method, the high-field conditioning of any arbitrary geometry and surface electric field distribution may be simulated for both RF and DC devices. Several phenomena observed in previous high-field tests such as the probabilistic behaviour of vacuum arcs and the inhomogeneous distribution of arc locations are described by this approach.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPORI24
About •	Received ※ 20 August 2022 — Revised ※ 22 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPORI26	Limits on Standing Wave Cavity Performance Due to Thermal Effects	287
SUPCRI02	use link to see paper's listing under its alternate paper code
	S.J. Smith, G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	After an RF cavity has been designed, a thermal analysis is typically performed to assess the effects of RF heating on the operating frequency and field flatness. A multi-physics approach (coupled electromagnetic, thermal, and mechanical) is normally employed, sometimes combined with computational fluid dynamics (CFD) simulations to incorporate flowing water, which is used for cooling in normal conducting structures. Performing a CFD analysis can add significant time to the design process because of the long and complex simulations and instead, approximations of the heat transfer coefficients and inlet/outlet water temperature rises are made and used directly in the multi-physics analysis. In this work, we first explore the limits of these approximations, identifying when they apply and how accurate they are. We then investigate different pipe geometries and water flow rates to find the thermal limits from RF heating on cavity performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPORI26
About •	Received ※ 17 August 2022 — Revised ※ 20 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

Fabrication, Field Measurement, and Testing of a Compact RF Deflecting Cavity for ELBE

271

T.G. Hallilingaiah, P. Michel, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
A. Arnold, S. Köppen, P. Michel
HZDR, Dresden, Germany
U. van Rienen
University of Rostock, Rostock, Germany

A transverse deflecting cavity is being developed for the electron linac ELBE to separate the bunches into two or more beamlines so that multiple user experiments can be carried out simultaneously. A normal conducting double quarter-wave cavity has been designed to deliver a transverse kick of 300 kV when driven by an 800 W solid-state amplifier at 273 MHz. The main challenges in fabrication were machining the complex cavity parts with high precision, pre-tuning the cavity frequency, and the final vacuum brazing within the tolerances, which are described in this paper. The reason for a low intrinsic quality factor measured during the low power test was investigated, and suitable steps were taken to improve the quality factor. The cavity field profiles obtained from the bead-pull measurement matched the simulation results. Further, the cavity was driven up to 1 kW using a modified pick-up antenna, and eventually, vacuum conditioning of the cavity was accomplished. The cavity fulfils the design requirements and is ready for beam tests.

Poster MOPORI20 [4.325 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPORI20

About •

Received ※ 14 August 2022 — Revised ※ 15 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 07 September 2022

Cite •

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

MOPORI22

High-Power Test of an APF IH-DTL Prototype for the Muon Linac

275

SUPCRI07

use link to see paper's listing under its alternate paper code

Y. Nakazawa, H. Iinuma
Ibaraki University, Ibaraki, Japan
E. Cicek, H. Ego, K. Futatsukawa, N. Kawamura, T. Mibe, S. Mizobata, N. Saito, M. Yoshida
KEK, Ibaraki, Japan
N. Hayashizaki
Research Laboratory for Nuclear Research, Tokyo Institute of Technology, Tokyo, Japan
Y. Iwata
NIRS, Chiba-shi, Japan
R. Kitamura, Y. Kondo, T. Morishita
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
M. Otani
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
Y. Sue, K. Sumi, M. Yotsuzuka
Nagoya University, Graduate School of Science, Chikusa-ku, Nagoya, Japan
Y. Takeuchi
Kyushu University, Fukuoka, Japan
T. Yamazaki
KEK, Tokai Branch, Tokai, Naka, Ibaraki, Japan
H.Y. Yasuda
University of Tokyo, Tokyo, Japan

A muon linac is under development for a new muon g-2/EDM experiment at J-PARC. The muons are cooled to about room temperature and then re-accelerated to 212 MeV by four linear accelerators to produce a low-emittance muon beam. In the low-beta section, a short-range acceleration cavity with high efficiency needs to be developed to suppress the decay of muons. We propose a 324 MHz inter-digital H-mode drift-tube linac (IH-DTL) with high acceleration efficiency. The cavity can be downsized by introducing the alternating phase focusing (APF) method that provides transverse focusing only with an E-field. We have developed a prototype cavity that accelerates muons up to 1.3 MeV to demonstrate the principle. In this paper, the result of the high power test of the APF IH-DTL prototype is reported.

Poster MOPORI22 [10.978 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPORI22

About •

Received ※ 13 August 2022 — Revised ※ 16 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 01 September 2022

Cite •

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

MOPORI23

High-Power Testing Results of X-Band RF-Window and 45 Degrees Spiral Load

279

M. Boronat, H. Bursali, N. Catalán Lasheras, A. Grudiev, G. McMonagle, I. Syratchev
CERN, Meyrin, Switzerland

The X-Band test facilities at CERN have been running for some years now qualifying CLIC structure prototypes but also developing and testing high power general-purpose X-Band components, used in a wide range of applications. Driven by operational needs, several components have been redesigned and tested aiming to optimize the reliability and the compactness of the full system and therefore enhancing the accessibility of this technology inside and outside CERN. To this extent, a new high-power RF-window has been designed and tested aiming to avoid unnecessary venting of high-power sections already conditioned, easing the interventions, and protecting the klystrons. A new spiral load prototype has also been designed, built, and tested, optimizing the compactness, and improving the fabrication process. In these pages, the design and manufacturing for each component will be shortly described, along with the last results on the high-power testing.

Poster MOPORI23 [2.275 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPORI23

About •

Received ※ 24 August 2022 — Revised ※ 29 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 31 August 2022

Cite •

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

MOPORI24

Monte Carlo Model of High-Voltage Conditioning and Operation

283

W.L. Millar, W. Wuensch
CERN, Meyrin, Switzerland
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

To synthesise the experimental results and theory pertaining to high-field phenomena, a model has been developed to simulate the conditioning and operation of high-field systems. By using a mesh-based method, the high-field conditioning of any arbitrary geometry and surface electric field distribution may be simulated for both RF and DC devices. Several phenomena observed in previous high-field tests such as the probabilistic behaviour of vacuum arcs and the inhomogeneous distribution of arc locations are described by this approach.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPORI24

About •

Received ※ 20 August 2022 — Revised ※ 22 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 15 September 2022

Cite •

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

MOPORI26

Limits on Standing Wave Cavity Performance Due to Thermal Effects

287

SUPCRI02

use link to see paper's listing under its alternate paper code

S.J. Smith, G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

After an RF cavity has been designed, a thermal analysis is typically performed to assess the effects of RF heating on the operating frequency and field flatness. A multi-physics approach (coupled electromagnetic, thermal, and mechanical) is normally employed, sometimes combined with computational fluid dynamics (CFD) simulations to incorporate flowing water, which is used for cooling in normal conducting structures. Performing a CFD analysis can add significant time to the design process because of the long and complex simulations and instead, approximations of the heat transfer coefficients and inlet/outlet water temperature rises are made and used directly in the multi-physics analysis. In this work, we first explore the limits of these approximations, identifying when they apply and how accurate they are. We then investigate different pipe geometries and water flow rates to find the thermal limits from RF heating on cavity performance.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPORI26

About •

Received ※ 17 August 2022 — Revised ※ 20 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 15 September 2022

Cite •

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