LINAC2016 - List of Keywords (impedance)

Paper	Title	Other Keywords	Page
MOOP03	High Gradient Accelerating Structures for Carbon Therapy Linac	linac, cavity, ion, operation	44
	S.V. Kutsaev, R.B. Agustsson, L. Faillace, E.A. Savin RadiaBeam, Santa Monica, California, USA A. Goel, B. Mustapha, A. Nassiri, P.N. Ostroumov, A.S. Plastun ANL, Argonne, Illinois, USA E.A. Savin MEPhI, Moscow, Russia
	Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, under contract 0000219678 Carbon therapy is the most promising among techniques for cancer treatment, as it has demonstrated significant improvements in clinical efficiency and reduced toxicity profiles in multiple types of cancer through much better localization of dose to the tumor volume. RadiaBeam, in collaboration with Argonne National Laboratory, are developing an ultra-high gradient linear accelerator, Advanced Compact Carbon Ion Linac (ACCIL), for the delivery of ion-beams with end-energies up to 450 MeV/u for 12C⁶⁺ ions and 250 MeV for protons. In this paper, we present a thorough comparison of standing and travelling wave designs for high gradient S-Band accelerating structures operating with ions at varying velocities, relative to the speed of light, in the range 0.3-0.7. In this paper we will compare these types of accelerating structures in terms of RF, beam dynamics and thermo-mechanical performance.
	Slides MOOP03 [3.497 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP03
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MOOP04	Traveling Wave Linear Accelerator With RF Power Flow Outside of Accelerating Cavities	coupling, linac, cavity, electron	48
	V.A. Dolgashev SLAC, Menlo Park, California, USA
	Funding: Work supported by the U.S. DOE under Contract No. DE-AC02-76-SF00515. An accelerating structure is a critical component of particle accelerators for medical, security, industrial and scientific applications. Standing-wave side-coupled accelerating structures are used where available RF power is at a premium, while average current and average RF power lost in the structure are high. These structures are expensive to manufacture and typically require a circulator to divert structure-reflected power away from RF source, klystron or magnetron. In this report a traveling wave accelerating structure is presented which combines high shunt impedance of the side-coupled standing wave structure with such advantages as simpler tuning and manufacturing. In addition, the structure is matched to the RF source so no circulator is needed. This paper presents the motivation for this structure and shows a practical example.
	Slides MOOP04 [5.459 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP04
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MOPLR011	Design of a Dielectric-lined Waveguide for Terahertz-driven Linear Electron Acceleration	electron, acceleration, accelerating-gradient, experiment	158
	A.L. Healy, G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom M.J. Cliffe, D.M. Graham The University of Manchester, The Photon Science Institute, Manchester, United Kingdom S.P. Jamison STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R. Valizadeh Cockcroft Institute, Warrington, Cheshire, United Kingdom
	A dielectric-lined waveguide has been designed for use as an accelerating structure in terahertz-driven electron acceleration experiments at Daresbury. Experimental verification of acceleration will take place on Versatile Electron Linear Accelerator (VELA). The choice of a rectangular waveguide structure with sidewall dielectric layers enables tuning by varying the spacing between dielectric slabs to account for potential manufacturing errors. Schemes for coupling free-space single cycle THz pulses into the waveguide have been evaluated and optimised through CST simulation. Comparison of simulation with experimental measurements will also be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR011
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MOPLR018	Upgrade of the Klystron Modulator of the L-Band Electron Linac at Osaka University for Higher Stability	klystron, resonance, linac, high-voltage	178
	K. Furukawa, G. Isoyama ISIR, Osaka, Japan R. Kato KEK, Ibaraki, Japan K. Kawase HSRC, Higashi-Hiroshima, Japan A. Tokuchi Pulsed Power Japan Laboratory Ltd., Kusatsu-shi Shiga, Japan
	The klystron modulator for the L-band linac is upgraded for higher stability. The two-step charging system for the pulse forming network (PFN) is upgraded by adding a high impedance resonant charging line in parallel with the main line. The charging step of the PFN voltage is reduced considerably near the setting value by switching the main resonance line off so that the charging current flows only through the high impedance line. The second model of the solid-state switch is developed using 60 static-induction thyristors, ten of which are connected in series with six such series connected in parallel to meet maximum specifications of 25 kV and 6 kA. The air-cooling capacity is reinforced so that repetition rate is increased from 10 pps for the first model to 60 pps. The fluctuation and accuracy of the klystron voltage are measured to be 7.8×10^-6 or 7.8 ppm for the upgraded klystron modulator using a differential amplifier with much higher sensitivity than one used in the previous measurement.
	Poster MOPLR018 [0.840 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR018
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MOPLR031	Wakefield Analysis of Superconducting RF-Dipole Cavities	wakefield, cavity, HOM, dipole	206
	S.U. De Silva, J.R. Delayen ODU, Norfolk, Virginia, USA
	RF-dipole crabbing cavities are being considered for a variety of crabbing applications. Some of the applications are the crabbing cavity systems for LHC High Luminosity Upgrade and the proposed Electron-Ion Collider for Jefferson Lab. The design requirements in the current applications require the cavities to incorporate complex damping schemes to suppress the higher order modes that may be excited by the high intensity proton or electron beams traversing through the cavities. The number of cavities required to achieve the desired high transverse voltage, and the complexity in the cavity geometries also contributes to the wakefields generated by beams. This paper characterizes the wakefield analysis for single cell and multi-cell rf-dipole cavities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR031
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MOPLR050	Study and Development of CW Room Temperature Rebuncher for SARAF Accelerator	cavity, vacuum, linac, acceleration	244
	B. Kaizer, Z. Horvitz, A. Perry, J. Rodnizki Soreq NRC, Yavne, Israel M. Di Giacomo, J.F. Leyge, M. Michel, P. Toussaint GANIL, Caen, France A. Friedman Ariel University, Ariel, Israel
	The SARAF 176 MHz accelerator is designed to provide CW proton/deuteron beams up to 5 mA current and 40 MeV accelerated ion energy. Phase I of SARAF (up to 4-5 MeV) has been installed, commissioned, and is available for experimental work. Phase II of SARAF is currently in the planning stage and will contain larger MEBT with three rebunchers and four cryomodules, each consisting of SC HWRs and solenoids. Phase II MEBT line is designed to follow a 1.3 MeV/u RFQ, is 4.5 m long, and contains three 176 MHz rebunchers providing a field integral of 10⁵ kV. Different rebuncher configurations have been studied in order to minimize the RF losses and maximize the shunt impedance. Different apertures have also been tested with a required of 40 mm diameter by beam dynamics. The simulations were done using CST Microwave Studio. CEA leads the design for SARAF phase II linac including the MEBT rebunchers and has studied a mixed solid copper and Cu plated stainless steel, 3-gap cavity. SNRC is developing a 4-gap OFHC copper rebuncher as a risk reduction. Both designs are presented and discussed in the paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR050
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MOPLR053	Operating Status of Injector II RFQ for C-ADS Project	rfq, cavity, coupling, scattering	254
	L.P. Sun, Y. He, C.X. Li, L. Lu, A. Shi, L.B. Shi, W.B. Wang, X.B. Xu, Z.L. Zhang, H.W. Zhao IMP/CAS, Lanzhou, People's Republic of China
	The Radio Frequency Quadrupole system has been designed and constructed for C-ADS (Chinese Accelerator Driven System) Injector II in Institute of Modern Physics (IMP), Chinese Academy of Sciences, which has been running for more than one year until now. It is a quadrilateral four-vane resonator with two equal couplers operating in CW mode. In the paper, RF system upgrade will be presented in detail，especially the two-port configuration was introduced and the conditioning based on two new sets of solid-state amplifier instead of the original tetrodes power source due to system hardware upgrade are described in the paper. RFQ, solid-state amplifier, two-port configuration, coupler
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR053
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TUPRC025	Low Temperature Nitrogen Baking of a Q0 SRF Cavities	cavity, niobium, SRF, radio-frequency	472
	P.N. Koufalis, F. Furuta, M. Ge, D. Gonnella, J.J. Kaufman, M. Liepe, J.T. Maniscalco, R.D. Porter Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Nitrogen-doping has led to an unprecedented increase in the intrinsic quality factor of bulk-niobium superconducting RF cavities. So far, high temperature baking in a nitrogen atmosphere is used almost exclusively to dope cavities. Recently, we have set focus on low temperature baking to produce similar performance increases and we present those results here.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC025
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TUPLR057	Advanced Design Optimizations of a Prototype for a Newly Revised 4-Rod CW RFQ for the HLI at GSI	rfq, dipole, resonance, simulation	586
	D. Koser, H. Podlech IAP, Frankfurt am Main, Germany P. Gerhard, L. Groening GSI, Darmstadt, Germany O.K. Kester TRIUMF, Vancouver, Canada
	Within the scope of the FAIR project (Facility for Antiproton and Ion Research) at GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, the front end of the existing High Charge State Injector (HLI) is upgraded for cw operation. The dedicated new 4-Rod RFQ structure is currently being designed at the Institute for Applied Physics (IAP) of the Goethe University of Frankfurt. The overall design is based on the RFQ structures that were originally developed for FRANZ* and MYRRHA*. Regarding the HLI-RFQ the comparatively low operating frequency of 10⁸ MHz causes a general susceptibility towards mechanical vibrations especially concerning the electrodes because of the necessarily larger distance between the stems. Besides RF simulations and basic thermal simulations with CST Studio Suite, the key issues like mechanical electrode oscillations as well as temperature distribution from heat loss in cw operation are investigated with simulations using ANSYS Workbench. At first instance a dedicated 6-stem prototype is currently being manufactured in order to validate the simulated RF performance, thermal behavior and structural mechanical characteristics. M. Heilmann et al., A Coupled RFQ-IH Cavity for the Neutron Source FRANZ, IPAC13 **C. Zhang, H. Podlech, New Reference Design of the European ADS RFQ Accelerator For MYRRHA, IPAC14
	Poster TUPLR057 [1.484 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR057
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TUPLR059	Asymmetric Four-Vane RFQ	dipole, quadrupole, rfq, simulation	592
	A.S. Plastun ANL, Argonne, Illinois, USA A. Kolomiets, D.A. Liakin ITEP, Moscow, Russia
	Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357. A four-vane resonator is widely used in Radio Frequency Quadrupole (RFQ) accelerators. The field distribution in a long four-vane resonator can be easily perturbed by nearest dipole modes which are excited due to the local geometry errors. This paper describes the electromagnetic properties of a four-vane resonator with an introduced asymmetry between neighboring chambers. The asymmetry provides necessary separation of dipole modes keeping losses and field uniformity of quadrupole mode similar to those in a conventional four-vane resonator. This feature of an asymmetric resonator is confirmed by analytical results from transmission line model as well as by CST Studio simulations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR059
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TH1A05	Towards Commissioning of the IFMIF RFQ	rfq, linac, vacuum, controls	698
	A. Pisent INFN/LNL, Legnaro (PD), Italy
	All 18 sections of the IFMIF RFQ were completed in summer 2015. A 2 m section (the last three modules and one prototype used as RF termination) were RF tested at LNL at the design value of 90 kW/m in cw conditions. The three 3.3 m long supermodules were sent to Japan in January 2016. The RFQ was installed and tuned with fixed tuners to the nominal field frequency and field distribution. The very high design shunt impedance was achieved.
	Slides TH1A05 [23.395 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TH1A05
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THOP10	Design and Commissioning of FRIB Multipacting-Free Fundamental Power Coupler	electron, cavity, cryomodule, controls	767
	Z. Zheng, J.T. Popielarski, K. Saito, S. Stark, T. Xu, Y. Yamazaki FRIB, East Lansing, USA
	Funding: *Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 The original Fundamental Power Coupler (FPC) of Half-Wave Resonator (HWR) for the Facility of Rare Isotope Beams (FRIB) requires multipacting conditioning at operating RF power which is up to 5 kW Continue Wave (CW). Conditioning takes a lot of time and RF power, and its elimination is highly desirable. To significantly shorten the RF conditioning, we developed a multipacting-free coupler design. This paper reports the latest progress in the optimization and prototype tests of multipacting-free coupler. The choke structure is removed and coupler geometry is further modified to protect the coupler RF window from the electron bombardment. The comparison result of multipacting-free coupler with original coupler was performed on automatic conditioning system, which showed significantly time reducing for RF conditioning.
	Slides THOP10 [2.442 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP10
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THPLR011	Traveling Wave Accelerating Structure Power Input Calculation With Equivalent Circuit Method	coupling, operation, interface, resonance	864
	S.V. Matsievskiy, V.I. Kaminskiy MEPhI, Moscow, Russia
	Nowadays linac accelerating RF systems design is usually done by the finite difference method. It provides high accuracy of calculations and freedom in topology choosing, but may draw considerable amounts of computer resources with long calculation times. Alternative to this method, equivalent circuit method exists. The basic idea of this method is to build a lumped element circuit, which with certain approximation acts as an original accelerating cell. It drastically reduces the number of equations to solve. This method is long known but usually only used for the particular accelerating structures when speed of calculation is a key-factor. This paper describes an attempt to create more universal and user-friendly software application for calculating electrical field distribution in accelerating structures, provides mathematical equations this software is based on. The resulting application may be used for preliminary calculations of acceleration structures and help to determine cells electrodynamic parameters reducing overall design time.
	Poster THPLR011 [0.789 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR011
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Paper

Title

Other Keywords

Page

MOOP03

High Gradient Accelerating Structures for Carbon Therapy Linac

linac, cavity, ion, operation

44

S.V. Kutsaev, R.B. Agustsson, L. Faillace, E.A. Savin
RadiaBeam, Santa Monica, California, USA
A. Goel, B. Mustapha, A. Nassiri, P.N. Ostroumov, A.S. Plastun
ANL, Argonne, Illinois, USA
E.A. Savin
MEPhI, Moscow, Russia

Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics, under contract 0000219678
Carbon therapy is the most promising among techniques for cancer treatment, as it has demonstrated significant improvements in clinical efficiency and reduced toxicity profiles in multiple types of cancer through much better localization of dose to the tumor volume. RadiaBeam, in collaboration with Argonne National Laboratory, are developing an ultra-high gradient linear accelerator, Advanced Compact Carbon Ion Linac (ACCIL), for the delivery of ion-beams with end-energies up to 450 MeV/u for 12C⁶⁺ ions and 250 MeV for protons. In this paper, we present a thorough comparison of standing and travelling wave designs for high gradient S-Band accelerating structures operating with ions at varying velocities, relative to the speed of light, in the range 0.3-0.7. In this paper we will compare these types of accelerating structures in terms of RF, beam dynamics and thermo-mechanical performance.

Slides MOOP03 [3.497 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP03

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MOOP04

Traveling Wave Linear Accelerator With RF Power Flow Outside of Accelerating Cavities

coupling, linac, cavity, electron

48

V.A. Dolgashev
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. DOE under Contract No. DE-AC02-76-SF00515.
An accelerating structure is a critical component of particle accelerators for medical, security, industrial and scientific applications. Standing-wave side-coupled accelerating structures are used where available RF power is at a premium, while average current and average RF power lost in the structure are high. These structures are expensive to manufacture and typically require a circulator to divert structure-reflected power away from RF source, klystron or magnetron. In this report a traveling wave accelerating structure is presented which combines high shunt impedance of the side-coupled standing wave structure with such advantages as simpler tuning and manufacturing. In addition, the structure is matched to the RF source so no circulator is needed. This paper presents the motivation for this structure and shows a practical example.

Slides MOOP04 [5.459 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOOP04

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MOPLR011

Design of a Dielectric-lined Waveguide for Terahertz-driven Linear Electron Acceleration

electron, acceleration, accelerating-gradient, experiment

158

A.L. Healy, G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
M.J. Cliffe, D.M. Graham
The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
S.P. Jamison
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R. Valizadeh
Cockcroft Institute, Warrington, Cheshire, United Kingdom

A dielectric-lined waveguide has been designed for use as an accelerating structure in terahertz-driven electron acceleration experiments at Daresbury. Experimental verification of acceleration will take place on Versatile Electron Linear Accelerator (VELA). The choice of a rectangular waveguide structure with sidewall dielectric layers enables tuning by varying the spacing between dielectric slabs to account for potential manufacturing errors. Schemes for coupling free-space single cycle THz pulses into the waveguide have been evaluated and optimised through CST simulation. Comparison of simulation with experimental measurements will also be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR011

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MOPLR018

Upgrade of the Klystron Modulator of the L-Band Electron Linac at Osaka University for Higher Stability

klystron, resonance, linac, high-voltage

178

K. Furukawa, G. Isoyama
ISIR, Osaka, Japan
R. Kato
KEK, Ibaraki, Japan
K. Kawase
HSRC, Higashi-Hiroshima, Japan
A. Tokuchi
Pulsed Power Japan Laboratory Ltd., Kusatsu-shi Shiga, Japan

The klystron modulator for the L-band linac is upgraded for higher stability. The two-step charging system for the pulse forming network (PFN) is upgraded by adding a high impedance resonant charging line in parallel with the main line. The charging step of the PFN voltage is reduced considerably near the setting value by switching the main resonance line off so that the charging current flows only through the high impedance line. The second model of the solid-state switch is developed using 60 static-induction thyristors, ten of which are connected in series with six such series connected in parallel to meet maximum specifications of 25 kV and 6 kA. The air-cooling capacity is reinforced so that repetition rate is increased from 10 pps for the first model to 60 pps. The fluctuation and accuracy of the klystron voltage are measured to be 7.8×10^-6 or 7.8 ppm for the upgraded klystron modulator using a differential amplifier with much higher sensitivity than one used in the previous measurement.

Poster MOPLR018 [0.840 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR018

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MOPLR031

Wakefield Analysis of Superconducting RF-Dipole Cavities

wakefield, cavity, HOM, dipole

206

S.U. De Silva, J.R. Delayen
ODU, Norfolk, Virginia, USA

RF-dipole crabbing cavities are being considered for a variety of crabbing applications. Some of the applications are the crabbing cavity systems for LHC High Luminosity Upgrade and the proposed Electron-Ion Collider for Jefferson Lab. The design requirements in the current applications require the cavities to incorporate complex damping schemes to suppress the higher order modes that may be excited by the high intensity proton or electron beams traversing through the cavities. The number of cavities required to achieve the desired high transverse voltage, and the complexity in the cavity geometries also contributes to the wakefields generated by beams. This paper characterizes the wakefield analysis for single cell and multi-cell rf-dipole cavities.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR031

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MOPLR050

Study and Development of CW Room Temperature Rebuncher for SARAF Accelerator

cavity, vacuum, linac, acceleration

244

B. Kaizer, Z. Horvitz, A. Perry, J. Rodnizki
Soreq NRC, Yavne, Israel
M. Di Giacomo, J.F. Leyge, M. Michel, P. Toussaint
GANIL, Caen, France
A. Friedman
Ariel University, Ariel, Israel

The SARAF 176 MHz accelerator is designed to provide CW proton/deuteron beams up to 5 mA current and 40 MeV accelerated ion energy. Phase I of SARAF (up to 4-5 MeV) has been installed, commissioned, and is available for experimental work. Phase II of SARAF is currently in the planning stage and will contain larger MEBT with three rebunchers and four cryomodules, each consisting of SC HWRs and solenoids. Phase II MEBT line is designed to follow a 1.3 MeV/u RFQ, is 4.5 m long, and contains three 176 MHz rebunchers providing a field integral of 10⁵ kV. Different rebuncher configurations have been studied in order to minimize the RF losses and maximize the shunt impedance. Different apertures have also been tested with a required of 40 mm diameter by beam dynamics. The simulations were done using CST Microwave Studio. CEA leads the design for SARAF phase II linac including the MEBT rebunchers and has studied a mixed solid copper and Cu plated stainless steel, 3-gap cavity. SNRC is developing a 4-gap OFHC copper rebuncher as a risk reduction. Both designs are presented and discussed in the paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR050

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MOPLR053

Operating Status of Injector II RFQ for C-ADS Project

rfq, cavity, coupling, scattering

254

L.P. Sun, Y. He, C.X. Li, L. Lu, A. Shi, L.B. Shi, W.B. Wang, X.B. Xu, Z.L. Zhang, H.W. Zhao
IMP/CAS, Lanzhou, People's Republic of China

The Radio Frequency Quadrupole system has been designed and constructed for C-ADS (Chinese Accelerator Driven System) Injector II in Institute of Modern Physics (IMP), Chinese Academy of Sciences, which has been running for more than one year until now. It is a quadrilateral four-vane resonator with two equal couplers operating in CW mode. In the paper, RF system upgrade will be presented in detail，especially the two-port configuration was introduced and the conditioning based on two new sets of solid-state amplifier instead of the original tetrodes power source due to system hardware upgrade are described in the paper.
RFQ, solid-state amplifier, two-port configuration, coupler

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR053

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TUPRC025

Low Temperature Nitrogen Baking of a Q0 SRF Cavities

cavity, niobium, SRF, radio-frequency

472

P.N. Koufalis, F. Furuta, M. Ge, D. Gonnella, J.J. Kaufman, M. Liepe, J.T. Maniscalco, R.D. Porter
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Nitrogen-doping has led to an unprecedented increase in the intrinsic quality factor of bulk-niobium superconducting RF cavities. So far, high temperature baking in a nitrogen atmosphere is used almost exclusively to dope cavities. Recently, we have set focus on low temperature baking to produce similar performance increases and we present those results here.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC025

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TUPLR057

Advanced Design Optimizations of a Prototype for a Newly Revised 4-Rod CW RFQ for the HLI at GSI

rfq, dipole, resonance, simulation

586

D. Koser, H. Podlech
IAP, Frankfurt am Main, Germany
P. Gerhard, L. Groening
GSI, Darmstadt, Germany
O.K. Kester
TRIUMF, Vancouver, Canada

Within the scope of the FAIR project (Facility for Antiproton and Ion Research) at GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, the front end of the existing High Charge State Injector (HLI) is upgraded for cw operation. The dedicated new 4-Rod RFQ structure is currently being designed at the Institute for Applied Physics (IAP) of the Goethe University of Frankfurt. The overall design is based on the RFQ structures that were originally developed for FRANZ* and MYRRHA**. Regarding the HLI-RFQ the comparatively low operating frequency of 10⁸ MHz causes a general susceptibility towards mechanical vibrations especially concerning the electrodes because of the necessarily larger distance between the stems. Besides RF simulations and basic thermal simulations with CST Studio Suite, the key issues like mechanical electrode oscillations as well as temperature distribution from heat loss in cw operation are investigated with simulations using ANSYS Workbench. At first instance a dedicated 6-stem prototype is currently being manufactured in order to validate the simulated RF performance, thermal behavior and structural mechanical characteristics.
*M. Heilmann et al., A Coupled RFQ-IH Cavity for the Neutron Source FRANZ, IPAC13
**C. Zhang, H. Podlech, New Reference Design of the European ADS RFQ Accelerator For MYRRHA, IPAC14

Poster TUPLR057 [1.484 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR057

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TUPLR059

Asymmetric Four-Vane RFQ

dipole, quadrupole, rfq, simulation

592

A.S. Plastun
ANL, Argonne, Illinois, USA
A. Kolomiets, D.A. Liakin
ITEP, Moscow, Russia

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
A four-vane resonator is widely used in Radio Frequency Quadrupole (RFQ) accelerators. The field distribution in a long four-vane resonator can be easily perturbed by nearest dipole modes which are excited due to the local geometry errors. This paper describes the electromagnetic properties of a four-vane resonator with an introduced asymmetry between neighboring chambers. The asymmetry provides necessary separation of dipole modes keeping losses and field uniformity of quadrupole mode similar to those in a conventional four-vane resonator. This feature of an asymmetric resonator is confirmed by analytical results from transmission line model as well as by CST Studio simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR059

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TH1A05

Towards Commissioning of the IFMIF RFQ

rfq, linac, vacuum, controls

698

A. Pisent
INFN/LNL, Legnaro (PD), Italy

All 18 sections of the IFMIF RFQ were completed in summer 2015. A 2 m section (the last three modules and one prototype used as RF termination) were RF tested at LNL at the design value of 90 kW/m in cw conditions. The three 3.3 m long supermodules were sent to Japan in January 2016. The RFQ was installed and tuned with fixed tuners to the nominal field frequency and field distribution. The very high design shunt impedance was achieved.

Slides TH1A05 [23.395 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TH1A05

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THOP10

Design and Commissioning of FRIB Multipacting-Free Fundamental Power Coupler

electron, cavity, cryomodule, controls

767

Z. Zheng, J.T. Popielarski, K. Saito, S. Stark, T. Xu, Y. Yamazaki
FRIB, East Lansing, USA

Funding: *Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
The original Fundamental Power Coupler (FPC) of Half-Wave Resonator (HWR) for the Facility of Rare Isotope Beams (FRIB) requires multipacting conditioning at operating RF power which is up to 5 kW Continue Wave (CW). Conditioning takes a lot of time and RF power, and its elimination is highly desirable. To significantly shorten the RF conditioning, we developed a multipacting-free coupler design. This paper reports the latest progress in the optimization and prototype tests of multipacting-free coupler. The choke structure is removed and coupler geometry is further modified to protect the coupler RF window from the electron bombardment. The comparison result of multipacting-free coupler with original coupler was performed on automatic conditioning system, which showed significantly time reducing for RF conditioning.

Slides THOP10 [2.442 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP10

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THPLR011

Traveling Wave Accelerating Structure Power Input Calculation With Equivalent Circuit Method

coupling, operation, interface, resonance

864

S.V. Matsievskiy, V.I. Kaminskiy
MEPhI, Moscow, Russia

Nowadays linac accelerating RF systems design is usually done by the finite difference method. It provides high accuracy of calculations and freedom in topology choosing, but may draw considerable amounts of computer resources with long calculation times. Alternative to this method, equivalent circuit method exists. The basic idea of this method is to build a lumped element circuit, which with certain approximation acts as an original accelerating cell. It drastically reduces the number of equations to solve. This method is long known but usually only used for the particular accelerating structures when speed of calculation is a key-factor. This paper describes an attempt to create more universal and user-friendly software application for calculating electrical field distribution in accelerating structures, provides mathematical equations this software is based on. The resulting application may be used for preliminary calculations of acceleration structures and help to determine cells electrodynamic parameters reducing overall design time.

Poster THPLR011 [0.789 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR011

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