LINAC2022 - List of Keywords (coupling)

Paper	Title	Other Keywords	Page
MOPOJO12	Design of a Compact Linac for High Average Power Radiotherapy	cavity, linac, GUI, gun	53
	C.D. Nantista, G.B. Bowden, Z. Li, M. Shumail, S.G. Tantawi SLAC, Menlo Park, California, USA B.W. Loo Stanford University, Stanford, California, USA
	We present the design of a compact, 10 MeV, 300 mA pulsed X-band linac developed for medical application. The layout, <1 m including gun, buncher, capture section and current monitor, is of a recent configuration in which the 36 main linac cavities are individually fed in parallel through side waveguide manifolds, allowing for split fabrication. Initially destined for experimental study of FLASH irradiation of mouse tumors, the design was developed as a prototype for realization of a PHASER cancer treatment machine, in which multiple linacs, powered sequentially from a common RF source, are to provide rapid treatment to patients from multiple directions without mechanical movement, delivering dosage on a time scale that essentially freezes the patient. In this paper, we focus on the RF design, beam capture optimization, mechanical design and fabrication of the linac itself, deferring discussion of other important aspects such as window and target design, experimental specification setting, radiation shielding and operations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOJO12
About •	Received ※ 22 August 2022 — Revised ※ 26 August 2022 — Accepted ※ 02 September 2022 — Issue date ※ 06 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOJO16	Cryogenic Accelerator Design for Compact Very High Energy Electron Therapy	cavity, linac, distributed, electron	62
	E.J.C. Snively, V. Borzenets, G.B. Bowden, A.K. Krasnykh, Z. Li, C.D. Nantista, M. Oriunno, M. Shumail, S.G. Tantawi SLAC, Menlo Park, California, USA B.W. Loo Stanford University, Stanford, California, USA
	Funding: This research has been supported by the U.S. Department of Energy (DOE) under Contract No. DE-C02-76SF00515. We report on the development of a cryogenic X-band (11.424 GHz) accelerator to provide electron beams for Very High Energy Electron therapy. The distributed coupling linac is designed with a 135° phase advance, capable of producing a 100 MeV/m accelerating gradient in a one-meter structure using only 19 MW when operating at 77 K. This peak power will be achieved through pulse compression of a 5-8 MW few-µs pulse, ensuring compatibility with a commercial power source. We present designs of the cryogenic linac and power distribution system, as well as a room temperature pulse compressor using the HE11 mode in a corrugated cavity. We discuss scaling this compact and economical design into a 16 linac array that can achieve FLASH dose rates (> 40 Gy/s) while eliminating the downtime associated with gantry motion.
	Slides MOPOJO16 [1.320 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOJO16
About •	Received ※ 14 August 2022 — Revised ※ 18 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 26 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOPA17	RF Commissioning of the First-of-Series Cavity Section of the Alvarez 2.0 at GSI	cavity, DTL, operation, vacuum	106
	M. Heilmann, L. Groening, C. Herr, M. Hoerr, S. Mickat, B. Schlitt, G. Schreiber GSI, Darmstadt, Germany
	The existing post-stripper DTL of the GSI UNILAC will be replaced with the new Alvarez 2.0 DTL to serve as the injector chain for the Facility of Antiproton and Ion Research (FAIR). The 10⁸.4 MHz Alvarez 2.0 DTL with a total length of 55 meters has an input energy of 1.36 MeV/u and the output energy is 11.32 MeV/u. The presented First-of-Series (FoS) cavity section with 11 drift tubes and a total length of 1.9 m is the first part of the first cavity of the Alvarez 2.0 DTL. After copper plating and assembly of the cavity the RF-conditioning started in July 2021. These proceeding gives an overview on the results of the successfully RF-conditioning to reach the necessary gap voltage for uranium operation including a comfortable safety margin.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOPA17
About •	Received ※ 24 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 01 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPOGE16	Development of High-Gradient Accelerating Structures for Proton Radiography Booster at LANSCE	cavity, booster, linac, proton	188
	S.S. Kurennoy, Y.K. Batygin, E.R. Olivas LANL, Los Alamos, New Mexico, USA
	Increasing energy of proton beam at LANSCE from 800 MeV to 3 GeV improves radiography resolution ~10 times. We propose accomplishing this energy boost with a compact cost-effective linac based on normal conducting high-gradient (HG) RF accelerating structures. Such an unusual proton linac is feasible for proton radiography (pRad), which operates with very short beam (and RF) pulses. For a compact pRad booster at LANSCE, we have developed a multi-stage design: a short L-band section to capture and compress the 800-MeV proton beam from the existing linac followed by the main HG linac based on S- and C-band cavities, and finally, by an L-band de-buncher. Here we present details of development, including EM and thermal-stress analysis, of proton HG structures with distributed RF coupling for the pRad booster. A short test structure is designed specifically for measurements at the LANL C-band RF Test Stand. S.S. Kurennoy, Y.K. Batygin. IPAC21, MOPAB210.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOGE16
About •	Received ※ 23 August 2022 — Accepted ※ 02 September 2022 — Issue date ※ 03 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOJO04	R&D for the Realization of a Very High Frequency Crossbar H-Mode Drift Tube Linac	cavity, DTL, linac, vacuum	341
	M. Heilmann, C. Zhang GSI, Darmstadt, Germany H. Podlech IAP, Frankfurt am Main, Germany
	A 704.4 MHz Crossbar H-mode (CH) drift tube linac has been proposed for performing a radio frequency jump at ß = 0.2. Up to now, the highest frequency of the constructed CH cavities is 360 MHz. Simulations have shown that the operation frequency for an H210-mode cavity can be up to ~800 MHz. At 704.4 MHz, the cavity dimensions become small, which bring challenges for many practical problems e.g. construction, vacuum pumping and RF coupling. This paper presents the performed R&D studies for the realization of such a very high frequency cavity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOJO04
About •	Received ※ 14 August 2022 — Revised ※ 19 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 31 August 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOJO05	Welding and Copper Plating Investigations on the FAIR Proton Linac	cavity, proton, linac, simulation	345
	A. Seibel, T. Dettinger, C.M. Kleffner, K. Knie, C. Will GSI, Darmstadt, Germany M.S. Breidt, H. Hähnel, U. Ratzinger IAP, Frankfurt am Main, Germany J. Egly PINK GmbH Vakuumtechnik, Wertheim, Germany
	A FAIR injector linac for the future FAIR facility is under construction. In order to meet the requirements for copper plating of the CH-cavities, a variety of tests with dummy cavities has been per-formed and compared to simulation. Further dummy cavities have been produced in order to improve the welding techniques. In addition, the results on 3d-printed stems with drift tubes will be presented.
	Poster TUPOJO05 [2.863 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOJO05
About •	Received ※ 08 August 2022 — Revised ※ 14 August 2022 — Accepted ※ 24 August 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOJO17	High Efficiency High Power Resonant Cavity Amplifier For PIP-II	cavity, impedance, network, electron	384
	R.E. Simpson, N. Butler, D.B. Cope, M.P.J. Gaudreau, M.K. Kempkes Diversified Technologies, Inc., Bedford, Massachusetts, USA
	An advanced high-power, high power density, solid state power amplifier (SSPA) was developed to replace Vacuum Electron Devices (VEDs). Diversified Technologies, Inc. (DTI) developed and integrated a resonant-cavity combiner with solid state amplifiers for the Proton Improvement Plan-II (PIP-II) at Fermilab. The architecture combines the power of N-many RF power transistors into a single resonant cavity that are surface-mounted and -cooled. The system is designed so that failure of individual transistors has negligible performance impact. Due to the electrical and mechanical simplicity, maintenance and logistics are simplified. DTI demonstrated the basic feasibility of a 50-100 kW class amplifier resonant cavity combiner system at 650 MHz. A single-cavity system reached 15 kW at 66% power-added efficiency with ten of 12 slots filled on only 1 of 2 cavities faces. The system further demonstrated the expected graceful degradation; an intermittent fault occurred on 1 of the 10 modules and the only observable effect was a reduction in output power to 13.3 kW with a slight reduction in efficiency. Combining of multiple cavities was also demonstrated at low power.
	Poster TUPOJO17 [0.790 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOJO17
About •	Received ※ 16 August 2022 — Revised ※ 25 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 15 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOPA03	Status and RF Devopments of ESS Bilbao RFQ	rfq, klystron, operation, vacuum	410
	N. Garmendia, I. Bustinduy, A. Conde, P.J. González, A. Kaftoosian, J. Martin, S. Masa, J.L. Muñoz, .A. Rodríguez Páramo ESS Bilbao, Zamudio, Spain
	Within the framework of the plans for study of a light-ion linear accelerator, ESS Bilbao is manufacturing a radio frequency quadrupole (RFQ) aimed at accelerating up to 3 MeV the protons generated in the ion source. The progress made and the difficulties encountered with the RFQ are discussed in this paper. A power coupler proto-type for the RFQ has been developed while several me-chanical constraints were also studied in the final cou-pler. This prototype operates at a lower power, then it can work using PEEK window for the vacuum interface and it does not require neither brazing nor cooling system. Also, a complete RF test stand is being implemented to perform the high-power conditioning in traveling and standing wave mode, to verify the power handling capa-bility of the coupler and its thermal behaviour. The RF test stand, based on EPICS environment, can provide up to 2 MW peak power at 352.2 MHz in a pulse operation of 14 Hz and a duty cycle of 4.9%.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA03
About •	Received ※ 09 August 2022 — Revised ※ 28 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 02 September 2022
Cite •	reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPOPA29	Design Enhancements for the SNS RFQ Coaxial Coupler	rfq, simulation, multipactoring, operation	469
	G.D. Toby, C.N. Barbier, Y.W. Kang, S.W. Lee, J.S. Moss ORNL, Oak Ridge, Tennessee, USA A.H. Narayan ORNL RAD, Oak Ridge, Tennessee, USA
	Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. This research was supported by the DOE Office of Science, Basic Energy Science. The H⁻ ion linear accelerator at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory operates with reliability that routinely surpasses 90% during scheduled beam operation. With the ambitious goal of eventually achieving at least 95% availability, several upgrade and improvement projects are ongoing. One such project is the modification of the coaxial couplers that transfer radio frequency (RF) power to the accelerator’s Radio Frequency Quadrupole (RFQ). The proposed modification utilizes stub sections and capacitive coupling to construct a physically separable assembly with DC isolation. With a separated coupler assembly, the section that includes the magnetic coupling loop can be permanently mounted to the RFQ which would eliminate the need to re-adjust the couplers after maintenance activities, upgrades, and repairs. Additionally, the modified design would provide increased multipaction suppression with DC biasing and potentially lower thermal gradients across the device. This paper presents the design and simulation results of the project.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA29
About •	Received ※ 23 August 2022 — Revised ※ 29 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 01 September 2022
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TUPOGE18	Operations of Copper Cavities at Cryogenic Temperatures	cavity, cryogenics, vacuum, experiment	533
	H. Wang, U. Ratzinger, M. Schuett IAP, Frankfurt am Main, Germany
	This work is focused on the anomalous skin effect in copper and how it affects the efficiency of copper-cavities in the temperature range 40-50 K. The quality factor Q of three coaxial cavities was measured over the temperature range from 10 K to room temperature in the experiment. The three coaxial cavities have the same structure, but different lengths, which correspond to resonant frequencies: around 100 MHz, 220 MHz and 340 MHz. Furthermore, the effects of copper-plating and additional baking in the vacuum oven on the quality factor Q are studied in the experiment. The motivation is to check the feasibility of an efficient, pulsed, ion linac, operated at cryogenic temperatures.
	Slides TUPOGE18 [1.115 MB]
	Poster TUPOGE18 [1.518 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOGE18
About •	Received ※ 22 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 02 September 2022 — Issue date ※ 03 September 2022
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THPOJO14	Distributed Coupling Linac for Efficient Acceleration of High Charge Electron Bunches	cavity, linac, distributed, electron	724
	A. Dhar, M. Bai, Z. Li, E.A. Nanni, M.A.K. Othman, S.G. Tantawi, G.R. White SLAC, Menlo Park, California, USA
	Funding: This work was supported by the Department of Energy Contract No. DE-AC02-76SF00515. The Electron Ion Collider requires a pre-injector linac to accelerate large electron bunches from 4 MeV up to 400 MeV over 35 m. Currently this linac is being designed with 3 m long traveling wave structures, which provide a gradient of 16 MV/m. We propose the use of a 1 m distributed coupling design as a potential alternative and future upgrade path to this design. Distributed coupling allows power to be fed into each cavity directly via a waveguide manifold, avoiding on-axis coupling. A distributed coupling structure at S-band was designed to optimize for shunt impedance and large aperture size. This design provides greater efficiency, thereby lowering the number of klystrons required to power the full linac. In addition, particle tracking analysis shows that this linac maintains lower emittance as bunch charge increases to 14 nC and wakefields become more prevalent. We present the design of this distributed coupling structure, as well as progress on structure manufacturing and characterization. F. Willeke, "Electron ion collider conceptual design report 2021," tech. rep., United States, 2021. ** S. Tantawi et al., Phys. Rev. Accel. Beams, vol. 23, p. 092001, Sep 2020.
	Poster THPOJO14 [5.280 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO14
About •	Received ※ 24 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 15 September 2022
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Paper

Title

Other Keywords

Page

MOPOJO12

Design of a Compact Linac for High Average Power Radiotherapy

cavity, linac, GUI, gun

53

C.D. Nantista, G.B. Bowden, Z. Li, M. Shumail, S.G. Tantawi
SLAC, Menlo Park, California, USA
B.W. Loo
Stanford University, Stanford, California, USA

We present the design of a compact, 10 MeV, 300 mA pulsed X-band linac developed for medical application. The layout, <1 m including gun, buncher, capture section and current monitor, is of a recent configuration in which the 36 main linac cavities are individually fed in parallel through side waveguide manifolds, allowing for split fabrication. Initially destined for experimental study of FLASH irradiation of mouse tumors, the design was developed as a prototype for realization of a PHASER cancer treatment machine, in which multiple linacs, powered sequentially from a common RF source, are to provide rapid treatment to patients from multiple directions without mechanical movement, delivering dosage on a time scale that essentially freezes the patient. In this paper, we focus on the RF design, beam capture optimization, mechanical design and fabrication of the linac itself, deferring discussion of other important aspects such as window and target design, experimental specification setting, radiation shielding and operations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOJO12

About •

Received ※ 22 August 2022 — Revised ※ 26 August 2022 — Accepted ※ 02 September 2022 — Issue date ※ 06 September 2022

Cite •

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

MOPOJO16

Cryogenic Accelerator Design for Compact Very High Energy Electron Therapy

cavity, linac, distributed, electron

62

E.J.C. Snively, V. Borzenets, G.B. Bowden, A.K. Krasnykh, Z. Li, C.D. Nantista, M. Oriunno, M. Shumail, S.G. Tantawi
SLAC, Menlo Park, California, USA
B.W. Loo
Stanford University, Stanford, California, USA

Funding: This research has been supported by the U.S. Department of Energy (DOE) under Contract No. DE-C02-76SF00515.
We report on the development of a cryogenic X-band (11.424 GHz) accelerator to provide electron beams for Very High Energy Electron therapy. The distributed coupling linac is designed with a 135° phase advance, capable of producing a 100 MeV/m accelerating gradient in a one-meter structure using only 19 MW when operating at 77 K. This peak power will be achieved through pulse compression of a 5-8 MW few-µs pulse, ensuring compatibility with a commercial power source. We present designs of the cryogenic linac and power distribution system, as well as a room temperature pulse compressor using the HE11 mode in a corrugated cavity. We discuss scaling this compact and economical design into a 16 linac array that can achieve FLASH dose rates (> 40 Gy/s) while eliminating the downtime associated with gantry motion.

Slides MOPOJO16 [1.320 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOJO16

About •

Received ※ 14 August 2022 — Revised ※ 18 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 26 September 2022

Cite •

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

MOPOPA17

RF Commissioning of the First-of-Series Cavity Section of the Alvarez 2.0 at GSI

cavity, DTL, operation, vacuum

106

M. Heilmann, L. Groening, C. Herr, M. Hoerr, S. Mickat, B. Schlitt, G. Schreiber
GSI, Darmstadt, Germany

The existing post-stripper DTL of the GSI UNILAC will be replaced with the new Alvarez 2.0 DTL to serve as the injector chain for the Facility of Antiproton and Ion Research (FAIR). The 10⁸.4 MHz Alvarez 2.0 DTL with a total length of 55 meters has an input energy of 1.36 MeV/u and the output energy is 11.32 MeV/u. The presented First-of-Series (FoS) cavity section with 11 drift tubes and a total length of 1.9 m is the first part of the first cavity of the Alvarez 2.0 DTL. After copper plating and assembly of the cavity the RF-conditioning started in July 2021. These proceeding gives an overview on the results of the successfully RF-conditioning to reach the necessary gap voltage for uranium operation including a comfortable safety margin.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOPA17

About •

Received ※ 24 August 2022 — Accepted ※ 29 August 2022 — Issue date ※ 01 September 2022

Cite •

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

MOPOGE16

Development of High-Gradient Accelerating Structures for Proton Radiography Booster at LANSCE

cavity, booster, linac, proton

188

S.S. Kurennoy, Y.K. Batygin, E.R. Olivas
LANL, Los Alamos, New Mexico, USA

Increasing energy of proton beam at LANSCE from 800 MeV to 3 GeV improves radiography resolution ~10 times. We propose accomplishing this energy boost with a compact cost-effective linac based on normal conducting high-gradient (HG) RF accelerating structures. Such an unusual proton linac is feasible for proton radiography (pRad), which operates with very short beam (and RF) pulses. For a compact pRad booster at LANSCE, we have developed a multi-stage design: a short L-band section to capture and compress the 800-MeV proton beam from the existing linac followed by the main HG linac based on S- and C-band cavities, and finally, by an L-band de-buncher*. Here we present details of development, including EM and thermal-stress analysis, of proton HG structures with distributed RF coupling for the pRad booster. A short test structure is designed specifically for measurements at the LANL C-band RF Test Stand.
* S.S. Kurennoy, Y.K. Batygin. IPAC21, MOPAB210.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-MOPOGE16

About •

Received ※ 23 August 2022 — Accepted ※ 02 September 2022 — Issue date ※ 03 September 2022

Cite •

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

TUPOJO04

R&D for the Realization of a Very High Frequency Crossbar H-Mode Drift Tube Linac

cavity, DTL, linac, vacuum

341

M. Heilmann, C. Zhang
GSI, Darmstadt, Germany
H. Podlech
IAP, Frankfurt am Main, Germany

A 704.4 MHz Crossbar H-mode (CH) drift tube linac has been proposed for performing a radio frequency jump at ß = 0.2. Up to now, the highest frequency of the constructed CH cavities is 360 MHz. Simulations have shown that the operation frequency for an H210-mode cavity can be up to ~800 MHz. At 704.4 MHz, the cavity dimensions become small, which bring challenges for many practical problems e.g. construction, vacuum pumping and RF coupling. This paper presents the performed R&D studies for the realization of such a very high frequency cavity.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOJO04

About •

Received ※ 14 August 2022 — Revised ※ 19 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 31 August 2022

Cite •

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

TUPOJO05

Welding and Copper Plating Investigations on the FAIR Proton Linac

cavity, proton, linac, simulation

345

A. Seibel, T. Dettinger, C.M. Kleffner, K. Knie, C. Will
GSI, Darmstadt, Germany
M.S. Breidt, H. Hähnel, U. Ratzinger
IAP, Frankfurt am Main, Germany
J. Egly
PINK GmbH Vakuumtechnik, Wertheim, Germany

A FAIR injector linac for the future FAIR facility is under construction. In order to meet the requirements for copper plating of the CH-cavities, a variety of tests with dummy cavities has been per-formed and compared to simulation. Further dummy cavities have been produced in order to improve the welding techniques. In addition, the results on 3d-printed stems with drift tubes will be presented.

Poster TUPOJO05 [2.863 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOJO05

About •

Received ※ 08 August 2022 — Revised ※ 14 August 2022 — Accepted ※ 24 August 2022 — Issue date ※ 15 September 2022

Cite •

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

TUPOJO17

High Efficiency High Power Resonant Cavity Amplifier For PIP-II

cavity, impedance, network, electron

384

R.E. Simpson, N. Butler, D.B. Cope, M.P.J. Gaudreau, M.K. Kempkes
Diversified Technologies, Inc., Bedford, Massachusetts, USA

An advanced high-power, high power density, solid state power amplifier (SSPA) was developed to replace Vacuum Electron Devices (VEDs). Diversified Technologies, Inc. (DTI) developed and integrated a resonant-cavity combiner with solid state amplifiers for the Proton Improvement Plan-II (PIP-II) at Fermilab. The architecture combines the power of N-many RF power transistors into a single resonant cavity that are surface-mounted and -cooled. The system is designed so that failure of individual transistors has negligible performance impact. Due to the electrical and mechanical simplicity, maintenance and logistics are simplified. DTI demonstrated the basic feasibility of a 50-100 kW class amplifier resonant cavity combiner system at 650 MHz. A single-cavity system reached 15 kW at 66% power-added efficiency with ten of 12 slots filled on only 1 of 2 cavities faces. The system further demonstrated the expected graceful degradation; an intermittent fault occurred on 1 of the 10 modules and the only observable effect was a reduction in output power to 13.3 kW with a slight reduction in efficiency. Combining of multiple cavities was also demonstrated at low power.

Poster TUPOJO17 [0.790 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOJO17

About •

Received ※ 16 August 2022 — Revised ※ 25 August 2022 — Accepted ※ 28 August 2022 — Issue date ※ 15 September 2022

Cite •

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

TUPOPA03

Status and RF Devopments of ESS Bilbao RFQ

rfq, klystron, operation, vacuum

410

N. Garmendia, I. Bustinduy, A. Conde, P.J. González, A. Kaftoosian, J. Martin, S. Masa, J.L. Muñoz, .A. Rodríguez Páramo
ESS Bilbao, Zamudio, Spain

Within the framework of the plans for study of a light-ion linear accelerator, ESS Bilbao is manufacturing a radio frequency quadrupole (RFQ) aimed at accelerating up to 3 MeV the protons generated in the ion source. The progress made and the difficulties encountered with the RFQ are discussed in this paper. A power coupler proto-type for the RFQ has been developed while several me-chanical constraints were also studied in the final cou-pler. This prototype operates at a lower power, then it can work using PEEK window for the vacuum interface and it does not require neither brazing nor cooling system. Also, a complete RF test stand is being implemented to perform the high-power conditioning in traveling and standing wave mode, to verify the power handling capa-bility of the coupler and its thermal behaviour. The RF test stand, based on EPICS environment, can provide up to 2 MW peak power at 352.2 MHz in a pulse operation of 14 Hz and a duty cycle of 4.9%.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA03

About •

Received ※ 09 August 2022 — Revised ※ 28 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 02 September 2022

Cite •

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

TUPOPA29

Design Enhancements for the SNS RFQ Coaxial Coupler

rfq, simulation, multipactoring, operation

469

G.D. Toby, C.N. Barbier, Y.W. Kang, S.W. Lee, J.S. Moss
ORNL, Oak Ridge, Tennessee, USA
A.H. Narayan
ORNL RAD, Oak Ridge, Tennessee, USA

Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. This research was supported by the DOE Office of Science, Basic Energy Science.
The H⁻ ion linear accelerator at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory operates with reliability that routinely surpasses 90% during scheduled beam operation. With the ambitious goal of eventually achieving at least 95% availability, several upgrade and improvement projects are ongoing. One such project is the modification of the coaxial couplers that transfer radio frequency (RF) power to the accelerator’s Radio Frequency Quadrupole (RFQ). The proposed modification utilizes stub sections and capacitive coupling to construct a physically separable assembly with DC isolation. With a separated coupler assembly, the section that includes the magnetic coupling loop can be permanently mounted to the RFQ which would eliminate the need to re-adjust the couplers after maintenance activities, upgrades, and repairs. Additionally, the modified design would provide increased multipaction suppression with DC biasing and potentially lower thermal gradients across the device. This paper presents the design and simulation results of the project.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOPA29

About •

Received ※ 23 August 2022 — Revised ※ 29 August 2022 — Accepted ※ 30 August 2022 — Issue date ※ 01 September 2022

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TUPOGE18

Operations of Copper Cavities at Cryogenic Temperatures

cavity, cryogenics, vacuum, experiment

533

H. Wang, U. Ratzinger, M. Schuett
IAP, Frankfurt am Main, Germany

This work is focused on the anomalous skin effect in copper and how it affects the efficiency of copper-cavities in the temperature range 40-50 K. The quality factor Q of three coaxial cavities was measured over the temperature range from 10 K to room temperature in the experiment. The three coaxial cavities have the same structure, but different lengths, which correspond to resonant frequencies: around 100 MHz, 220 MHz and 340 MHz. Furthermore, the effects of copper-plating and additional baking in the vacuum oven on the quality factor Q are studied in the experiment. The motivation is to check the feasibility of an efficient, pulsed, ion linac, operated at cryogenic temperatures.

Slides TUPOGE18 [1.115 MB]

Poster TUPOGE18 [1.518 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-TUPOGE18

About •

Received ※ 22 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 02 September 2022 — Issue date ※ 03 September 2022

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THPOJO14

Distributed Coupling Linac for Efficient Acceleration of High Charge Electron Bunches

cavity, linac, distributed, electron

724

A. Dhar, M. Bai, Z. Li, E.A. Nanni, M.A.K. Othman, S.G. Tantawi, G.R. White
SLAC, Menlo Park, California, USA

Funding: This work was supported by the Department of Energy Contract No. DE-AC02-76SF00515.
The Electron Ion Collider requires a pre-injector linac to accelerate large electron bunches from 4 MeV up to 400 MeV over 35 m*. Currently this linac is being designed with 3 m long traveling wave structures, which provide a gradient of 16 MV/m. We propose the use of a 1 m distributed coupling design as a potential alternative and future upgrade path to this design. Distributed coupling allows power to be fed into each cavity directly via a waveguide manifold, avoiding on-axis coupling**. A distributed coupling structure at S-band was designed to optimize for shunt impedance and large aperture size. This design provides greater efficiency, thereby lowering the number of klystrons required to power the full linac. In addition, particle tracking analysis shows that this linac maintains lower emittance as bunch charge increases to 14 nC and wakefields become more prevalent. We present the design of this distributed coupling structure, as well as progress on structure manufacturing and characterization.
* F. Willeke, "Electron ion collider conceptual design report 2021," tech. rep., United States, 2021.
** S. Tantawi et al., Phys. Rev. Accel. Beams, vol. 23, p. 092001, Sep 2020.

Poster THPOJO14 [5.280 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2022-THPOJO14

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Received ※ 24 August 2022 — Revised ※ 31 August 2022 — Accepted ※ 01 September 2022 — Issue date ※ 15 September 2022

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