IPAC2021 - List of Authors (Grudiev, A.)

Paper	Title	Page
MOPAB142	A Compact, Low-Field, Broadband Matching Section for Externally-Powered X-Band Dielectric-Loaded Accelerating Structures	495
	Y. Wei, C.P. Welsch The University of Liverpool, Liverpool, United Kingdom H. Bursali Sapienza University of Rome, Rome, Italy N. Catalán Lasheras, S. Gonzalez Anton, A. Grudiev, R. Wegner, Y. Wei CERN, Meyrin, Switzerland B.T. Freemire, C.-J. Jing Euclid TechLabs, Solon, Ohio, USA J. Sauza-Bedolla Lancaster University, Lancaster, United Kingdom Y. Wei, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	It has been technically challenging to efficiently couple external radiofrequency (RF) power to cylindrical dielectric-loaded accelerating (DLA) structures. This is especially true when the DLA structure has a high dielectric constant. This contribution presents a novel design of a matching section for coupling the RF power from a circular waveguide to an X-band DLA structure with a dielectric constant ε_r=16.66 and a loss tangent \tanθ = 3.43× 10^-5. It consists of a very compact dielectric disk with a width of 2.035 mm and a tilt angle of 60 degrees, resulting in a broadband coupling at a low RF field which has the potential to survive in the high-power environment. To prevent a sharp dielectric corner break, a 45-degree chamfer is added. Moreover, a microscale vacuum gap, caused by metallic clamping between the thin coating and the outer thick copper jacket, is studied in detail. Based on simulation studies, a prototype of the DLA structure with the matching sections was fabricated. Results from preliminary bench measurements and their comparison with design values will also be discussed.
	Poster MOPAB142 [2.617 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB142
About •	paper received ※ 11 May 2021 paper accepted ※ 21 May 2021 issue date ※ 19 August 2021
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MOPAB370	X-Band RF Spiral Load Optimization for Additive Manufacturing Mass Production	1143
	H. Bursali Sapienza University of Rome, Rome, Italy N. Catalán Lasheras, R.L. Gerard, A. Grudiev, O. Gumenyuk, P. Morales Sanchez, B. Riffaud CERN, Geneva, Switzerland J. Sauza-Bedolla Lancaster University, Lancaster, United Kingdom
	The CLIC main linac uses X-band traveling-wave normal conducting accelerating structures. The RF power not used for beam acceleration nor dissipated in the resistive wall is absorbed in two high power RF loads that should be as compact as possible to minimize the total footprint of the machine. In recent years, CERN has designed, fabricated and successfully tested several loads produced by additive manufacturing. With the current design, only one load can be produced in the 3D printing machine at a time. The aim of this study is optimizing the internal cross-section of loads in order to create a stackable design to increase the number of produced parts per manufacturing cycle and thus decrease the unit price. This paper presents the new design with an optimization of the internal vacuum part of the so-called RF spiral load. In this case, RF and mechanical designs were carried out in parallel. The new cross section has showed good RF reflection reaching less than -30 dB in simulations. The final load is now ready to be manufactured and high-power tested. This new load will not only provide cost saving but also faster manufacturing for mass production.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB370
About •	paper received ※ 18 May 2021 paper accepted ※ 26 May 2021 issue date ※ 23 August 2021
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TUPAB076	High-Gradient Breakdown Studies of an X-Band Accelerating Structure Operated in the Reversed Taper Direction	1543
	X.W. Wu, N. Catalán Lasheras, A. Grudiev, G. McMonagle, I. Syratchev, W. Wuensch CERN, Meyrin, Switzerland M. Boronat IFIC, Valencia, Spain A. Castilla, A.V. Edwards, W.L. Millar Lancaster University, Lancaster, United Kingdom
	The results of high-gradient tests of a tapered X-band traveling-wave accelerator structure powered in reversed direction are presented. Powering the tapered structure from the small aperture, normally output, at the end of the structure provides unique conditions for the study of gradient limits. This allows high fields in the first cell for a comparatively low input power and a field distribution that rapidly falls off along the length of the structure. A maximum gradient of 130 MV/m in the first cell at a pulse length of 100 ns was reached for an input power of 31.9 MW. Details of the conditioning and operation at high-gradient are presented. Various breakdown rate measurements were conducted at different power levels and rf pulse widths. The structure was standard T24 CLIC test structure and was tested in Xbox-3 at CERN.
	Poster TUPAB076 [1.077 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB076
About •	paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 12 August 2021
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TUPAB077	Novel Open Cavity for Rotating Mode SLED-Type RF Pulse Compressors	1547
	X.W. Wu, A. Grudiev CERN, Meyrin, Switzerland
	A new X-band high-power rotating mode SLAC Energy Doubler (SLED)-type rf pulse compressor is proposed. It is based on a novel cavity type, a single open bowl-shape energy storage cavity with high Q₀ and compact size, which is coupled to the waveguide using a compact rotating mode launcher. The novel cavity type is applied to the rf pulse compression system of the main linac rf module of the klystron-based option of the Compact Linear Collider (CLIC). Quasi-spherical rotating modes of \rm{TE}_1,2,4 and \rm{TE}_1,2,13 are proposed for the correction cavity and storage cavity of the rf pulse compression system respectively. The storage cavity working at \rm{TE}_1,2,13 has a Q₀ of 240000 and a diameter less than 33 cm. The design of the pulse compressor and in particular of the high-Q cavity will be presented in detail.
	Poster TUPAB077 [1.229 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB077
About •	paper received ※ 19 May 2021 paper accepted ※ 10 June 2021 issue date ※ 27 August 2021
Export •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

Paper

Title

Page

A Compact, Low-Field, Broadband Matching Section for Externally-Powered X-Band Dielectric-Loaded Accelerating Structures

495

Y. Wei, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
H. Bursali
Sapienza University of Rome, Rome, Italy
N. Catalán Lasheras, S. Gonzalez Anton, A. Grudiev, R. Wegner, Y. Wei
CERN, Meyrin, Switzerland
B.T. Freemire, C.-J. Jing
Euclid TechLabs, Solon, Ohio, USA
J. Sauza-Bedolla
Lancaster University, Lancaster, United Kingdom
Y. Wei, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

It has been technically challenging to efficiently couple external radiofrequency (RF) power to cylindrical dielectric-loaded accelerating (DLA) structures. This is especially true when the DLA structure has a high dielectric constant. This contribution presents a novel design of a matching section for coupling the RF power from a circular waveguide to an X-band DLA structure with a dielectric constant ε_r=16.66 and a loss tangent \tanθ = 3.43× 10^-5. It consists of a very compact dielectric disk with a width of 2.035 mm and a tilt angle of 60 degrees, resulting in a broadband coupling at a low RF field which has the potential to survive in the high-power environment. To prevent a sharp dielectric corner break, a 45-degree chamfer is added. Moreover, a microscale vacuum gap, caused by metallic clamping between the thin coating and the outer thick copper jacket, is studied in detail. Based on simulation studies, a prototype of the DLA structure with the matching sections was fabricated. Results from preliminary bench measurements and their comparison with design values will also be discussed.

Poster MOPAB142 [2.617 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB142

About •

paper received ※ 11 May 2021 paper accepted ※ 21 May 2021 issue date ※ 19 August 2021

Export •

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

MOPAB370

X-Band RF Spiral Load Optimization for Additive Manufacturing Mass Production

1143

H. Bursali
Sapienza University of Rome, Rome, Italy
N. Catalán Lasheras, R.L. Gerard, A. Grudiev, O. Gumenyuk, P. Morales Sanchez, B. Riffaud
CERN, Geneva, Switzerland
J. Sauza-Bedolla
Lancaster University, Lancaster, United Kingdom

The CLIC main linac uses X-band traveling-wave normal conducting accelerating structures. The RF power not used for beam acceleration nor dissipated in the resistive wall is absorbed in two high power RF loads that should be as compact as possible to minimize the total footprint of the machine. In recent years, CERN has designed, fabricated and successfully tested several loads produced by additive manufacturing. With the current design, only one load can be produced in the 3D printing machine at a time. The aim of this study is optimizing the internal cross-section of loads in order to create a stackable design to increase the number of produced parts per manufacturing cycle and thus decrease the unit price. This paper presents the new design with an optimization of the internal vacuum part of the so-called RF spiral load. In this case, RF and mechanical designs were carried out in parallel. The new cross section has showed good RF reflection reaching less than -30 dB in simulations. The final load is now ready to be manufactured and high-power tested. This new load will not only provide cost saving but also faster manufacturing for mass production.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB370

About •

paper received ※ 18 May 2021 paper accepted ※ 26 May 2021 issue date ※ 23 August 2021

Export •

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

TUPAB076

High-Gradient Breakdown Studies of an X-Band Accelerating Structure Operated in the Reversed Taper Direction

1543

X.W. Wu, N. Catalán Lasheras, A. Grudiev, G. McMonagle, I. Syratchev, W. Wuensch
CERN, Meyrin, Switzerland
M. Boronat
IFIC, Valencia, Spain
A. Castilla, A.V. Edwards, W.L. Millar
Lancaster University, Lancaster, United Kingdom

The results of high-gradient tests of a tapered X-band traveling-wave accelerator structure powered in reversed direction are presented. Powering the tapered structure from the small aperture, normally output, at the end of the structure provides unique conditions for the study of gradient limits. This allows high fields in the first cell for a comparatively low input power and a field distribution that rapidly falls off along the length of the structure. A maximum gradient of 130 MV/m in the first cell at a pulse length of 100 ns was reached for an input power of 31.9 MW. Details of the conditioning and operation at high-gradient are presented. Various breakdown rate measurements were conducted at different power levels and rf pulse widths. The structure was standard T24 CLIC test structure and was tested in Xbox-3 at CERN.

Poster TUPAB076 [1.077 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB076

About •

paper received ※ 19 May 2021 paper accepted ※ 12 July 2021 issue date ※ 12 August 2021

Export •

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

TUPAB077

Novel Open Cavity for Rotating Mode SLED-Type RF Pulse Compressors

1547

X.W. Wu, A. Grudiev
CERN, Meyrin, Switzerland

A new X-band high-power rotating mode SLAC Energy Doubler (SLED)-type rf pulse compressor is proposed. It is based on a novel cavity type, a single open bowl-shape energy storage cavity with high Q₀ and compact size, which is coupled to the waveguide using a compact rotating mode launcher. The novel cavity type is applied to the rf pulse compression system of the main linac rf module of the klystron-based option of the Compact Linear Collider (CLIC). Quasi-spherical rotating modes of \rm{TE}_1,2,4 and \rm{TE}_1,2,13 are proposed for the correction cavity and storage cavity of the rf pulse compression system respectively. The storage cavity working at \rm{TE}_1,2,13 has a Q₀ of 240000 and a diameter less than 33 cm. The design of the pulse compressor and in particular of the high-Q cavity will be presented in detail.

Poster TUPAB077 [1.229 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB077

About •

paper received ※ 19 May 2021 paper accepted ※ 10 June 2021 issue date ※ 27 August 2021

Export •

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