LINAC2016 - List of Keywords (DTL)

Paper	Title	Other Keywords	Page
MOPRC013	Tracking Based Courant-Snyder Parameter Matching in a Linac with a Strong Space-Charge Force	linac, space-charge, emittance, quadrupole	93
	R. Miyamoto ESS, Lund, Sweden
	During the design of a hadron linac, matching at the interfaces of different structures or lattice periods is often performed with the linear approximation of the space-charge force. When space-charge is extremely strong, like in the low energy part of the proton linac of the European Spallation Source, such a matching method is not always good enough and could lead to a residual mismatch at the design level. To avoid this, a matching scheme based on iterations of tracking, thus including the full effect of the space-charge force, is developed. This paper presents the scheme itself as well as its application to the ESS linac.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC013
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MOPRC018	Improved Beam Dynamics and Cavity RF Design for the FAIR Proton Injector	cavity, linac, proton, quadrupole	111
	R. Tiede, A. Almomani, M. Busch, F.D. Dziuba, U. Ratzinger IAP, Frankfurt am Main, Germany
	The FAIR facility at GSI requires a dedicated 70 MeV, 70 mA proton injector for the research program with intense antiproton beams. The main accelerator part consists of six 'Crossbar H-type' (CH) cavities operated at 325 MHz. Based on a linac layout carefully developed over several years, recently the beam dynamics has been revised with the scope of finalising the design and thus being able to start the construction of the main linac components. As compared to previous designs the MEBT behind the RFQ was slightly extended, the gap numbers per CH cavity and the voltage distributions were optimised and the layout of the intermediate diagnostics section including a rebuncher cavity at 33 MeV was redesigned. Finally, detailed machine error studies were performed in order to check the error response of the new design and the steering concept in particular. In the consequence, the final parameters obtained from the beam dynamics update are used for finalizing the CH-DTL cavity design by CST-MWS calculations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC018
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MOPLR049	Design of a 750 MHz IH Structure for Medical Applications	rfq, dipole, linac, proton	240
	S. Benedetti, A. Grudiev, A. Latina CERN, Geneva, Switzerland
	Low velocity particles are critical in every hadron accelerator chain. While RFQs nicely cover the first MeV/u range, providing both acceleration and bunching, energies higher than few MeV/u require different structures, depending on the specific application. In the framework of the TULIP project [1], a 750 MHz IH structure was designed, in order to cover the 5-10 MeV/u range. The relatively high operating frequency and small bore aperture radius led the choice towards TE mode structures over more classic DTLs. Hereafter, the RF regular cell and end cell optimization is presented. An innovative solution to compensate dipole kicks is discussed, together with the beam dynamics and the matching with the 5 MeV 750 MHz CERN RFQ [2]. This structure was specifically designed for medical applications with a duty cycle of about 1 ', but can easily adapted to duty cycles up to 5 %, typical of PET isotopes production in hospitals.
	Poster MOPLR049 [3.212 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR049
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MOPLR059	Commissioning Plans for the ESS DTL	linac, emittance, diagnostics, proton	264
	M. Comunian, L. Bellan, F. Grespan, A. Pisent INFN/LNL, Legnaro (PD), Italy M. Eshraqi, R. Miyamoto ESS, Lund, Sweden
	The Drift Tube Linac (DTL) of the European Spallation Source (ESS) is designed to operate at 352.2 MHz with a duty cycle of 4% (a beam pulse of 2.86 ms, 14 Hz repetition period) and will accelerate a proton beam of 62.5 mA pulse peak current from 3.62 to 90 MeV. This article describes the commissioning strategy plans for the DTL part of the linac, techniques for finding the RF set-point of the 5 tanks and steering approach. Typical beam parameters, as proposed for commissioning purposes, are discussed as well and how the commissioning sequence of the tanks fits together with ongoing installation works in the tunnel.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR059
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MOPLR069	Implication of Manufacturing Errors on the Layout of Stabilization System and on the Field Quality in a Drift Tube Linac - RF DTL Error Study	linac, simulation, emittance, drift-tube-linac	290
	R. De Prisco, A.R. Karlsson Lund University, Lund, Sweden M. Eshraqi, Y.I. Levinsen, R. Miyamoto ESS, Lund, Sweden
	The field flatness and the layout of the stabilization system in a drift tube linac are strongly dependent on the manufacturing errors that affect the local resonant frequency. In this paper a methodology is presented to study, firstly, the sensitivity of the resonant frequency and of the field flatness to each geometrical parameter of the drift tubes; then a set of tolerances for each parameter is found and a stabilization system layout is defined in order to keep the field flatness within an acceptable limit.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR069
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MOPLR070	Integration of Interfaces and Stabilization System in the Design of a Drift Tube Linac	simulation, vacuum, interface, linac	294
	R. De Prisco, A.R. Karlsson Lund University, Lund, Sweden M. Eshraqi, Y.I. Levinsen, R. Miyamoto ESS, Lund, Sweden
	Making an accurate RF design of any accelerating structure is fundamental to ensure that electromagnetic and beam dynamics requirements will be achieved. This is essential for the most complicated accelerating structures like the drift tube linac: in this case a meticulous design facilitates the RF commissioning too. In this paper the influence of the interfaces and of the field stabilization system on the RF design is analyzed and an advanced design methodology to mitigate field degradation is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR070
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MOPLR072	The Effect of DTL Cavity Field Errors on Beam Spill at LANSCE	cavity, linac, LLRF, target	301
	L. Rybarcyk, R.C. McCrady LANL, Los Alamos, New Mexico, USA
	The Los Alamos Neutron Science Center (LANSCE) accelerator comprises two (H⁺ and H⁻) 750-keV Cockcroft-Walton style injectors, a 201.25-MHz, 100-MeV drift-tube linac (DTL) and an 805-MHz, 800-MeV coupled-cavity linac (CCL). As part of the LANSCE Risk Mitigation project a new digital low-level radio frequency (LLRF) control system is being deployed across the linac, starting with the DTL. Related to this upgrade, a study was performed where specific cavity field errors were simultaneously introduced in all DTL tanks about the nominal stable, low-spill, production set points to mimic LLRF control errors. The impact of these errors on the resultant beam spill was quantified for the nominal 100 μA, 800-MeV Lujan beam. We present the details of the measurement approach and results that show a rapid increase in total linac beam spill as DTL cavity field phase and amplitude errors are increased.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR072
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TU1A01	Review on Trends in Normal Conducting Linacs for Protons, Ions and Electrons, With Emphasis on New Technologies and Applications	linac, rfq, proton, electron	336
	F. Gerigk CERN, Geneva, Switzerland
	In recent years a lot of attention was given to developments in the field of superconducting cavities. While these cavities can save operating costs and shorten the length of linacs, there are many applications and circumstances where normal conducting cavities are superior. This talk reviews some of the normal conducting linacs, which have been either recently commissioned, or which are currently under construction or in the design phase. Focus will be given to the choice between normal and superconducting cavities and to emerging normal conducting technologies and their applications.
	Slides TU1A01 [16.553 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TU1A01
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TU1A03	Experience with the Construction and Commissioning of Linac4	linac, ion, emittance, cavity	342
	J.-B. Lallement CERN, Geneva, Switzerland
	In the framework of the LHC Injector Upgrade program, CERN is presently commissioning Linac4, a 160MeV H⁻ ion linac, which will replace the present 50 MeV proton linac (Linac2) as injector to the PS Booster during the next LHC long shut-down. The installation of the machine has proceeded in parallel with a staged beam commissioning at the energies of 3, 12, 50, 100 MeV and finally 160 MeV, foreseen for fall 2016. A seven month long reliability run will take place during 2017 to access potential weak points and find mitigations. The lessons learnt during its construction, the main outcomes of the beam commissioning and the remaining steps toward its connection to the PS Booster are presented in this paper.
	Slides TU1A03 [5.747 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TU1A03
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TU2A02	Pulsed High Power Klystron Modulators for ESS Linac Based on the Stacked Multi-Level Topology	klystron, linac, operation, flattop	359
	C.A. Martins, G. Göransson, M. Kalafatic ESS, Lund, Sweden M. Collins Lund Technical University, Lund, Sweden
	ESS has launched an internal R&D project in view of designing, prototyping and validating a klystron modulator compatible with the requirements based on a novel topology named SML (Stacked Multi-Level). This topology is modular and based on the utilization of High Frequency (HF) transformers. The topology allows for the usage of industrial standard power electronic components at the primary stage at full extent which can easily be placed and wired in a conventional electrical cabinet. It requires only few special components like HF transformers, rectifiers and filters (i.e. passive components) to be placed in an oil tank. This arrangement allows scaling up in average and pulse power to the required levels while keeping the size, cost, efficiency and reliability of the different modules under good control. Besides the very good output pulse power quality, the AC grid power quality is also remarkably high with a line current harmonic distortion below 3%, a unitary power factor and an extremely reduced line voltage flicker below 0.3%. A reduced scale modulator prototype has been built and validated experimentally.
	Slides TU2A02 [8.596 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TU2A02
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TUPRC002	ESS DTL Beam Dynamics Comparison Between S-Code and T-Code	emittance, simulation, software, linac	411
	M. Comunian, L. Bellan, F. Grespan, A. Pisent INFN/LNL, Legnaro (PD), Italy L. Bellan Univ. degli Studi di Padova, Padova, Italy
	The Drift Tube Linac (DTL) of the European Spallation Source (ESS) is designed to operate at 352.2 MHz with a duty cycle of 4% (3 ms pulse length, 14 Hz repetition period) and will accelerate a proton beam of 62.5 mA pulse peak current from 3.62 to 90 MeV. In this paper the DTL beam dynamics comparison between the s-code TraceWin and the t-code Parmela is presented. Full field map of the permanent magnet quadrupoles (with COMSOL) and RF fields of each of the 5 tanks (with MDTFish) were used for the two programs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPRC002
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TUPLR038	The DTL Post Coupler - An Ingenious Invention Turns 50	linac, cavity, drift-tube-linac, proton	547
	S. Ramberger CERN, Geneva, Switzerland M.R. Khalvati IPM, Tehran, Iran
	In September 1967, the patent for "A method and device for stabilization of the field distribution in drift tube linac" has been filed by Edward A. Knapp, Donald A. Swenson, and James M. Potter of Los Alamos National Laboratory. It is this invention which to a good part led to the success of highly efficient Alvarez drift tube linacs (DTLs) in that it considerably reduces field errors. The explanation for why the post coupler when tuned correctly has such a strong stabilizing effect has been given at the time in an accompanying paper by describing the modal confluence of the accelerating mode band with the post-coupler mode band, turning a comparatively sensitive 0-mode structure into a stable pi/2-mode like structure. As ingenious as the invention of the post-coupler appears, as poor has been the way of finding its optimum length by relying mainly on trial and error. With the design of the Linac4 DTL at CERN, a new technique has been derived by a DTL equivalent circuit model. Understanding stabilization on an almost cell by cell level provides a new way of optimizing post-couplers of an entire structure with few measurements and even without the extraction of the circuit model itself. Previous approaches to post-coupler stabilization are reviewed and the new, straightforward and accurate technique is described and demonstrated in the stabilization of the Linac4 DTL structures.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR038
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TUPLR046	Design, Fabrication, Installation and Operation of New 201 MHz RF Systems at LANSCE	linac, controls, cavity, feedback	564
	J.T.M. Lyles, W.C. Barkley, R.E. Bratton, M.S. Prokop, D. Rees LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396. The LANSCE RM project has restored the proton linac to high power capability after the RF power tube manufacturer could no longer provide devices that consistently met the high average power requirement. Diacrodes® now supply RF power to three of the four DTL tanks. These tetrodes reuse the existing infrastructure including water-cooling systems, coaxial transmission lines, high voltage power supplies and capacitor banks. Each final power amplifier system uses a combined pair of LANL-designed cavity amplifiers using the TH628L Diacrode® to produce up to 3.5 MW peak and 420 kW of mean power. A new intermediate power amplifier was developed using a TH781 tetrode. These amplifiers are the first production of new high power 200 MHz RF sources at accelerators in three decades. Design and prototype testing of the high power stages was completed in 2012, with commercialization following in 2013. Each installation was accomplished during a 4 to 5 month beam outage each year staring in 2014. Simultaneously, a new digital low-level RF control system was designed and tested, and placed into operation this year, meeting the stringent field control requirements for the linac. The rapid-paced installation project changed over from old to new RF systems while minimizing beam downtime to the user facility schedule.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR046
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TUPLR070	Efficient Heavy Ion Acceleration with IH-Type Cavities for High Current Machines in the Energy Range up to 11.4 MeV/u	linac, emittance, simulation, cavity	616
	H. Hähnel, U. Ratzinger, R. Tiede IAP, Frankfurt am Main, Germany
	Funding: BMBF 05P15RFRBA We propose an efficient design for heavy ion acceleration from 1.4 to 11.4 MeV/u with a design current of 15 emA for a Uranium 28+ beam. The proposed linac is based on IH-DTL cavities and quadrupole triplet focusing. The KONUS beam dynamics concept is used to achieve high acceleration efficiency. By optimization of the transversal focusing scheme and the longitudinal bunch center motion, low emittance growth for the entire linac is achieved. Beam dynamics simulations were performed along with 3D rf-simulations of all cavities. The cavities are designed for 10⁸.408 MHz, reaching an effective shunt impedance of 100-200 MOhm/m. The overall length of the linac is below 25 m. A mechanical realization concept employing a modular tank design is presented. The proposed design is a viable option for the GSI UNILAC poststripper linac replacement, leaving free space in the UNILAC tunnel for future energy upgrades.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TUPLR070
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TH1A02	Operation of KOMAC 100 MeV Linac	target, linac, operation, ion	683
	H.S. Kim KAERI, Daejon, Republic of Korea Y.-S. Cho, H.-J. Kwon Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea
	Funding: This work was supported by the Ministry of Science, ICT & Future Planning of the Korean Government. A 100-MeV proton linear accelerator at the KOMAC (Korea Multi-purpose Accelerator Complex) was under development for past 15 years, including preliminary design study period, and was successfully commissioned in 2013. The operation of the linac for user service started in July 2013 with two beam lines: one for a 20-MeV beam and the other for a 100-MeV beam. The linac is composed of a 50-keV microwave proton source, a 3-MeV four-vane-type RFQ (radio-frequency quadrupole) and a 100-MeV DTL (drift tube linac). In 2015, the linac operating time was more than 2,800 hours with an availability of better than 89% and unscheduled downtime was about 73 hours, mainly due to the ion source and HVCM problems. More than 2,100 samples from various fields such as material science, bio and nano technology and nuclear science, were treated in 2015. Currently, additional beamline for radioisotope production is being commissioned and a new beamline for low-flux irradiation experiments are under construction along with a continuous effort being made to increase the average beam power.
	Slides TH1A02 [18.355 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TH1A02
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TH1A03	Development of New Heavy Ion Linacs at GSI	linac, emittance, ion, solenoid	688
	L. Groening, S. Mickat GSI, Darmstadt, Germany
	The heavy ion linac UNILAC at GSI will be upgraded in order to meet the beam requirements imposed by the upcoming FAIR facility. This upgrade includes several innovative techniques and applications. They comprise a new gaseaous stripper with enhanced efficiency, full 4d transverse emittance measurements, a round-to-flat beam adaptor, asymmetric transverse focusing along the new Alvarez DTL, optimized shape of the drift tube surface w.r.t. shunt impedance per surface field, and a field stabilization and tuning scheme without post-couplers. Additionally, we report on development of a super-conducting cw linac for intermediate mass ions which will be dedicated to production of super heavy elements close to the Coulomb barrier.
	Slides TH1A03 [3.016 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-TH1A03
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THOP06	Novel Scheme to Tune RF Cavities Using Reflected Power	cavity, controls, resonance, TRIUMF	757
	R. Leewe, K. Fong, Z. Shahriari TRIUMF, Vancouver, Canada M. Moallem SFU, Surrey, Canada
	Tuning of the natural resonance frequency of an RF cavity is essential for accelerator structures to achieve efficient beam acceleration and to reduce power requirements. Typically operational cavities are tuned using phase comparison techniques. The phase measurement is subject to temperature drifts and renders this technique labor and time intensive. To eliminate the phase measurement, reduce human oversight and speed up the start-up time for each cavity, this paper presents a control scheme that relies solely on the reflected power measurements. A sliding mode extremum seeking algorithm is used to minimize the reflected power. To avoid tuning motor abrasion, a variable gain minimizes motor movement around the optimum operating point. The system has been tested and is fully commissioned on two drift tube linear accelerator tanks in TRIUMF's ISAC I linear accelerator. Experimental results show that the resonance frequency can be tuned to its optimum operating point while the start-up time of a single cavity and the accompanied human oversight are significantly decreased.
	Poster THOP06 [0.244 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THOP06
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THPLR042	Beam Dynamics Studies for a Compact Carbon Ion Linac for Therapy	ion, linac, focusing, rfq	946
	A.S. Plastun, B. Mustapha, A. Nassiri, P.N. Ostroumov ANL, Argonne, Illinois, USA L. Faillace, S.V. Kutsaev, E.A. Savin RadiaBeam, Santa Monica, California, 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 Accelerator Stewardship Grant, Proposal No. 0000219678 Feasibility of an Advanced Compact Carbon Ion Linac (ACCIL) for hadron therapy is being studied at Argonne National Laboratory in collaboration with RadiaBeam Technologies. The 45-meter long linac is designed to deliver 10⁹ carbon ions per second with variable energy from 45 MeV/u to 450 MeV/u. S-band structure provides the acceleration in this range. The carbon beam energy can be adjusted from pulse to pulse, making 3D tumor scanning straightforward and fast. Front end accelerating structures such as RFQ, DTL and coupled DTL are designed to operate at lower frequencies. The design of the linac was accompanied with extensive end-to-end beam dynamics studies which are presented in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR042
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THPLR060	Experience with the Conditioning of Linac4 RF Cavities	cavity, vacuum, linac, coupling	985
	S. Papadopoulos, F. Gerigk, J.-M. Giguet, J. Hansen, J. Marques Balula, A.I. Michet, S. Ramberger, N. Thaus, R. Wegner CERN, Geneva, Switzerland
	Linac4, the future H⁻ injector of the PS complex at CERN has reached the hardware and beam commissioning phase. This paper summarizes the experience gained in RF conditioning of the DTL, CCDTL and PIMS cavities. The behaviour in conditioning of these cavities strongly depends on the cavity type and assembly conditions. Examples of conditioning history and vacuum measurements before, during and after conditioning are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-THPLR060
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THPLR061	Research on a Two-beam Type Drift Tube Linac	ion, heavy-ion, cavity, acceleration	989
	L. Lu, C.X. Li, W. Ma, L.B. Shi, L.P. Sun, X.B. Xu, H.W. Zhao IMP/CAS, Lanzhou, People's Republic of China T.L. He USTC/NSRL, Hefei, Anhui, People's Republic of China L. Yang USTC, Hefei, Anhui, People's Republic of China
	The very high intense heavy-ion beam is a high attraction for heavy ion researches and heavy-ion applications, but it is limited by heavy-ion production of ion source and space-charge-effect in acceleration. There is one way, accelerating several heavy-ion beams in one cavity at same time and funneling them, which could achieve the acceleration of very high intense heavy-ion beam with existing ion source and accelerating technology. In this paper, we will introduce our designs, calculations and simulations of a 2-beam type drift tube linac.
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Paper

Title

Other Keywords

Page

MOPRC013

Tracking Based Courant-Snyder Parameter Matching in a Linac with a Strong Space-Charge Force

linac, space-charge, emittance, quadrupole

93

R. Miyamoto
ESS, Lund, Sweden

During the design of a hadron linac, matching at the interfaces of different structures or lattice periods is often performed with the linear approximation of the space-charge force. When space-charge is extremely strong, like in the low energy part of the proton linac of the European Spallation Source, such a matching method is not always good enough and could lead to a residual mismatch at the design level. To avoid this, a matching scheme based on iterations of tracking, thus including the full effect of the space-charge force, is developed. This paper presents the scheme itself as well as its application to the ESS linac.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC013

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MOPRC018

Improved Beam Dynamics and Cavity RF Design for the FAIR Proton Injector

cavity, linac, proton, quadrupole

111

R. Tiede, A. Almomani, M. Busch, F.D. Dziuba, U. Ratzinger
IAP, Frankfurt am Main, Germany

The FAIR facility at GSI requires a dedicated 70 MeV, 70 mA proton injector for the research program with intense antiproton beams. The main accelerator part consists of six 'Crossbar H-type' (CH) cavities operated at 325 MHz. Based on a linac layout carefully developed over several years, recently the beam dynamics has been revised with the scope of finalising the design and thus being able to start the construction of the main linac components. As compared to previous designs the MEBT behind the RFQ was slightly extended, the gap numbers per CH cavity and the voltage distributions were optimised and the layout of the intermediate diagnostics section including a rebuncher cavity at 33 MeV was redesigned. Finally, detailed machine error studies were performed in order to check the error response of the new design and the steering concept in particular. In the consequence, the final parameters obtained from the beam dynamics update are used for finalizing the CH-DTL cavity design by CST-MWS calculations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPRC018

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MOPLR049

Design of a 750 MHz IH Structure for Medical Applications

rfq, dipole, linac, proton

240

S. Benedetti, A. Grudiev, A. Latina
CERN, Geneva, Switzerland

Low velocity particles are critical in every hadron accelerator chain. While RFQs nicely cover the first MeV/u range, providing both acceleration and bunching, energies higher than few MeV/u require different structures, depending on the specific application. In the framework of the TULIP project [1], a 750 MHz IH structure was designed, in order to cover the 5-10 MeV/u range. The relatively high operating frequency and small bore aperture radius led the choice towards TE mode structures over more classic DTLs. Hereafter, the RF regular cell and end cell optimization is presented. An innovative solution to compensate dipole kicks is discussed, together with the beam dynamics and the matching with the 5 MeV 750 MHz CERN RFQ [2]. This structure was specifically designed for medical applications with a duty cycle of about 1 ', but can easily adapted to duty cycles up to 5 %, typical of PET isotopes production in hospitals.

Poster MOPLR049 [3.212 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR049

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MOPLR059

Commissioning Plans for the ESS DTL

linac, emittance, diagnostics, proton

264

M. Comunian, L. Bellan, F. Grespan, A. Pisent
INFN/LNL, Legnaro (PD), Italy
M. Eshraqi, R. Miyamoto
ESS, Lund, Sweden

The Drift Tube Linac (DTL) of the European Spallation Source (ESS) is designed to operate at 352.2 MHz with a duty cycle of 4% (a beam pulse of 2.86 ms, 14 Hz repetition period) and will accelerate a proton beam of 62.5 mA pulse peak current from 3.62 to 90 MeV. This article describes the commissioning strategy plans for the DTL part of the linac, techniques for finding the RF set-point of the 5 tanks and steering approach. Typical beam parameters, as proposed for commissioning purposes, are discussed as well and how the commissioning sequence of the tanks fits together with ongoing installation works in the tunnel.

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reference for this paper ※ https://doi.org/10.18429/JACoW-LINAC2016-MOPLR059

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MOPLR069

Implication of Manufacturing Errors on the Layout of Stabilization System and on the Field Quality in a Drift Tube Linac - RF DTL Error Study

linac, simulation, emittance, drift-tube-linac

290

R. De Prisco, A.R. Karlsson
Lund University, Lund, Sweden
M. Eshraqi, Y.I. Levinsen, R. Miyamoto
ESS, Lund, Sweden

The field flatness and the layout of the stabilization system in a drift tube linac are strongly dependent on the manufacturing errors that affect the local resonant frequency. In this paper a methodology is presented to study, firstly, the sensitivity of the resonant frequency and of the field flatness to each geometrical parameter of the drift tubes; then a set of tolerances for each parameter is found and a stabilization system layout is defined in order to keep the field flatness within an acceptable limit.

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MOPLR070

Integration of Interfaces and Stabilization System in the Design of a Drift Tube Linac

simulation, vacuum, interface, linac

294

R. De Prisco, A.R. Karlsson
Lund University, Lund, Sweden
M. Eshraqi, Y.I. Levinsen, R. Miyamoto
ESS, Lund, Sweden

Making an accurate RF design of any accelerating structure is fundamental to ensure that electromagnetic and beam dynamics requirements will be achieved. This is essential for the most complicated accelerating structures like the drift tube linac: in this case a meticulous design facilitates the RF commissioning too. In this paper the influence of the interfaces and of the field stabilization system on the RF design is analyzed and an advanced design methodology to mitigate field degradation is presented.

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MOPLR072

The Effect of DTL Cavity Field Errors on Beam Spill at LANSCE

cavity, linac, LLRF, target

301

L. Rybarcyk, R.C. McCrady
LANL, Los Alamos, New Mexico, USA

The Los Alamos Neutron Science Center (LANSCE) accelerator comprises two (H⁺ and H⁻) 750-keV Cockcroft-Walton style injectors, a 201.25-MHz, 100-MeV drift-tube linac (DTL) and an 805-MHz, 800-MeV coupled-cavity linac (CCL). As part of the LANSCE Risk Mitigation project a new digital low-level radio frequency (LLRF) control system is being deployed across the linac, starting with the DTL. Related to this upgrade, a study was performed where specific cavity field errors were simultaneously introduced in all DTL tanks about the nominal stable, low-spill, production set points to mimic LLRF control errors. The impact of these errors on the resultant beam spill was quantified for the nominal 100 μA, 800-MeV Lujan beam. We present the details of the measurement approach and results that show a rapid increase in total linac beam spill as DTL cavity field phase and amplitude errors are increased.

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TU1A01

Review on Trends in Normal Conducting Linacs for Protons, Ions and Electrons, With Emphasis on New Technologies and Applications

linac, rfq, proton, electron

336

F. Gerigk
CERN, Geneva, Switzerland

In recent years a lot of attention was given to developments in the field of superconducting cavities. While these cavities can save operating costs and shorten the length of linacs, there are many applications and circumstances where normal conducting cavities are superior. This talk reviews some of the normal conducting linacs, which have been either recently commissioned, or which are currently under construction or in the design phase. Focus will be given to the choice between normal and superconducting cavities and to emerging normal conducting technologies and their applications.

Slides TU1A01 [16.553 MB]

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TU1A03

Experience with the Construction and Commissioning of Linac4

linac, ion, emittance, cavity

342

J.-B. Lallement
CERN, Geneva, Switzerland

In the framework of the LHC Injector Upgrade program, CERN is presently commissioning Linac4, a 160MeV H⁻ ion linac, which will replace the present 50 MeV proton linac (Linac2) as injector to the PS Booster during the next LHC long shut-down. The installation of the machine has proceeded in parallel with a staged beam commissioning at the energies of 3, 12, 50, 100 MeV and finally 160 MeV, foreseen for fall 2016. A seven month long reliability run will take place during 2017 to access potential weak points and find mitigations. The lessons learnt during its construction, the main outcomes of the beam commissioning and the remaining steps toward its connection to the PS Booster are presented in this paper.

Slides TU1A03 [5.747 MB]

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TU2A02

Pulsed High Power Klystron Modulators for ESS Linac Based on the Stacked Multi-Level Topology

klystron, linac, operation, flattop

359

C.A. Martins, G. Göransson, M. Kalafatic
ESS, Lund, Sweden
M. Collins
Lund Technical University, Lund, Sweden

ESS has launched an internal R&D project in view of designing, prototyping and validating a klystron modulator compatible with the requirements based on a novel topology named SML (Stacked Multi-Level). This topology is modular and based on the utilization of High Frequency (HF) transformers. The topology allows for the usage of industrial standard power electronic components at the primary stage at full extent which can easily be placed and wired in a conventional electrical cabinet. It requires only few special components like HF transformers, rectifiers and filters (i.e. passive components) to be placed in an oil tank. This arrangement allows scaling up in average and pulse power to the required levels while keeping the size, cost, efficiency and reliability of the different modules under good control. Besides the very good output pulse power quality, the AC grid power quality is also remarkably high with a line current harmonic distortion below 3%, a unitary power factor and an extremely reduced line voltage flicker below 0.3%. A reduced scale modulator prototype has been built and validated experimentally.

Slides TU2A02 [8.596 MB]

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TUPRC002

ESS DTL Beam Dynamics Comparison Between S-Code and T-Code

emittance, simulation, software, linac

411

M. Comunian, L. Bellan, F. Grespan, A. Pisent
INFN/LNL, Legnaro (PD), Italy
L. Bellan
Univ. degli Studi di Padova, Padova, Italy

The Drift Tube Linac (DTL) of the European Spallation Source (ESS) is designed to operate at 352.2 MHz with a duty cycle of 4% (3 ms pulse length, 14 Hz repetition period) and will accelerate a proton beam of 62.5 mA pulse peak current from 3.62 to 90 MeV. In this paper the DTL beam dynamics comparison between the s-code TraceWin and the t-code Parmela is presented. Full field map of the permanent magnet quadrupoles (with COMSOL) and RF fields of each of the 5 tanks (with MDTFish) were used for the two programs.

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TUPLR038

The DTL Post Coupler - An Ingenious Invention Turns 50

linac, cavity, drift-tube-linac, proton

547

S. Ramberger
CERN, Geneva, Switzerland
M.R. Khalvati
IPM, Tehran, Iran

In September 1967, the patent for "A method and device for stabilization of the field distribution in drift tube linac" has been filed by Edward A. Knapp, Donald A. Swenson, and James M. Potter of Los Alamos National Laboratory. It is this invention which to a good part led to the success of highly efficient Alvarez drift tube linacs (DTLs) in that it considerably reduces field errors. The explanation for why the post coupler when tuned correctly has such a strong stabilizing effect has been given at the time in an accompanying paper by describing the modal confluence of the accelerating mode band with the post-coupler mode band, turning a comparatively sensitive 0-mode structure into a stable pi/2-mode like structure. As ingenious as the invention of the post-coupler appears, as poor has been the way of finding its optimum length by relying mainly on trial and error. With the design of the Linac4 DTL at CERN, a new technique has been derived by a DTL equivalent circuit model. Understanding stabilization on an almost cell by cell level provides a new way of optimizing post-couplers of an entire structure with few measurements and even without the extraction of the circuit model itself. Previous approaches to post-coupler stabilization are reviewed and the new, straightforward and accurate technique is described and demonstrated in the stabilization of the Linac4 DTL structures.

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TUPLR046

Design, Fabrication, Installation and Operation of New 201 MHz RF Systems at LANSCE

linac, controls, cavity, feedback

564

J.T.M. Lyles, W.C. Barkley, R.E. Bratton, M.S. Prokop, D. Rees
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396.
The LANSCE RM project has restored the proton linac to high power capability after the RF power tube manufacturer could no longer provide devices that consistently met the high average power requirement. Diacrodes® now supply RF power to three of the four DTL tanks. These tetrodes reuse the existing infrastructure including water-cooling systems, coaxial transmission lines, high voltage power supplies and capacitor banks. Each final power amplifier system uses a combined pair of LANL-designed cavity amplifiers using the TH628L Diacrode® to produce up to 3.5 MW peak and 420 kW of mean power. A new intermediate power amplifier was developed using a TH781 tetrode. These amplifiers are the first production of new high power 200 MHz RF sources at accelerators in three decades. Design and prototype testing of the high power stages was completed in 2012, with commercialization following in 2013. Each installation was accomplished during a 4 to 5 month beam outage each year staring in 2014. Simultaneously, a new digital low-level RF control system was designed and tested, and placed into operation this year, meeting the stringent field control requirements for the linac. The rapid-paced installation project changed over from old to new RF systems while minimizing beam downtime to the user facility schedule.

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TUPLR070

Efficient Heavy Ion Acceleration with IH-Type Cavities for High Current Machines in the Energy Range up to 11.4 MeV/u

linac, emittance, simulation, cavity

616

H. Hähnel, U. Ratzinger, R. Tiede
IAP, Frankfurt am Main, Germany

Funding: BMBF 05P15RFRBA
We propose an efficient design for heavy ion acceleration from 1.4 to 11.4 MeV/u with a design current of 15 emA for a Uranium 28+ beam. The proposed linac is based on IH-DTL cavities and quadrupole triplet focusing. The KONUS beam dynamics concept is used to achieve high acceleration efficiency. By optimization of the transversal focusing scheme and the longitudinal bunch center motion, low emittance growth for the entire linac is achieved. Beam dynamics simulations were performed along with 3D rf-simulations of all cavities. The cavities are designed for 10⁸.408 MHz, reaching an effective shunt impedance of 100-200 MOhm/m. The overall length of the linac is below 25 m. A mechanical realization concept employing a modular tank design is presented. The proposed design is a viable option for the GSI UNILAC poststripper linac replacement, leaving free space in the UNILAC tunnel for future energy upgrades.

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TH1A02

Operation of KOMAC 100 MeV Linac

target, linac, operation, ion

683

H.S. Kim
KAERI, Daejon, Republic of Korea
Y.-S. Cho, H.-J. Kwon
Korea Atomic Energy Research Institute (KAERI), Gyeongbuk, Republic of Korea

Funding: This work was supported by the Ministry of Science, ICT & Future Planning of the Korean Government.
A 100-MeV proton linear accelerator at the KOMAC (Korea Multi-purpose Accelerator Complex) was under development for past 15 years, including preliminary design study period, and was successfully commissioned in 2013. The operation of the linac for user service started in July 2013 with two beam lines: one for a 20-MeV beam and the other for a 100-MeV beam. The linac is composed of a 50-keV microwave proton source, a 3-MeV four-vane-type RFQ (radio-frequency quadrupole) and a 100-MeV DTL (drift tube linac). In 2015, the linac operating time was more than 2,800 hours with an availability of better than 89% and unscheduled downtime was about 73 hours, mainly due to the ion source and HVCM problems. More than 2,100 samples from various fields such as material science, bio and nano technology and nuclear science, were treated in 2015. Currently, additional beamline for radioisotope production is being commissioned and a new beamline for low-flux irradiation experiments are under construction along with a continuous effort being made to increase the average beam power.

Slides TH1A02 [18.355 MB]

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TH1A03

Development of New Heavy Ion Linacs at GSI

linac, emittance, ion, solenoid

688

L. Groening, S. Mickat
GSI, Darmstadt, Germany

The heavy ion linac UNILAC at GSI will be upgraded in order to meet the beam requirements imposed by the upcoming FAIR facility. This upgrade includes several innovative techniques and applications. They comprise a new gaseaous stripper with enhanced efficiency, full 4d transverse emittance measurements, a round-to-flat beam adaptor, asymmetric transverse focusing along the new Alvarez DTL, optimized shape of the drift tube surface w.r.t. shunt impedance per surface field, and a field stabilization and tuning scheme without post-couplers. Additionally, we report on development of a super-conducting cw linac for intermediate mass ions which will be dedicated to production of super heavy elements close to the Coulomb barrier.

Slides TH1A03 [3.016 MB]

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THOP06

Novel Scheme to Tune RF Cavities Using Reflected Power

cavity, controls, resonance, TRIUMF

757

R. Leewe, K. Fong, Z. Shahriari
TRIUMF, Vancouver, Canada
M. Moallem
SFU, Surrey, Canada

Tuning of the natural resonance frequency of an RF cavity is essential for accelerator structures to achieve efficient beam acceleration and to reduce power requirements. Typically operational cavities are tuned using phase comparison techniques. The phase measurement is subject to temperature drifts and renders this technique labor and time intensive. To eliminate the phase measurement, reduce human oversight and speed up the start-up time for each cavity, this paper presents a control scheme that relies solely on the reflected power measurements. A sliding mode extremum seeking algorithm is used to minimize the reflected power. To avoid tuning motor abrasion, a variable gain minimizes motor movement around the optimum operating point. The system has been tested and is fully commissioned on two drift tube linear accelerator tanks in TRIUMF's ISAC I linear accelerator. Experimental results show that the resonance frequency can be tuned to its optimum operating point while the start-up time of a single cavity and the accompanied human oversight are significantly decreased.

Poster THOP06 [0.244 MB]

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THPLR042

Beam Dynamics Studies for a Compact Carbon Ion Linac for Therapy

ion, linac, focusing, rfq

946

A.S. Plastun, B. Mustapha, A. Nassiri, P.N. Ostroumov
ANL, Argonne, Illinois, USA
L. Faillace, S.V. Kutsaev, E.A. Savin
RadiaBeam, Santa Monica, California, 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 Accelerator Stewardship Grant, Proposal No. 0000219678
Feasibility of an Advanced Compact Carbon Ion Linac (ACCIL) for hadron therapy is being studied at Argonne National Laboratory in collaboration with RadiaBeam Technologies. The 45-meter long linac is designed to deliver 10⁹ carbon ions per second with variable energy from 45 MeV/u to 450 MeV/u. S-band structure provides the acceleration in this range. The carbon beam energy can be adjusted from pulse to pulse, making 3D tumor scanning straightforward and fast. Front end accelerating structures such as RFQ, DTL and coupled DTL are designed to operate at lower frequencies. The design of the linac was accompanied with extensive end-to-end beam dynamics studies which are presented in this paper.

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THPLR060

Experience with the Conditioning of Linac4 RF Cavities

cavity, vacuum, linac, coupling

985

S. Papadopoulos, F. Gerigk, J.-M. Giguet, J. Hansen, J. Marques Balula, A.I. Michet, S. Ramberger, N. Thaus, R. Wegner
CERN, Geneva, Switzerland

Linac4, the future H⁻ injector of the PS complex at CERN has reached the hardware and beam commissioning phase. This paper summarizes the experience gained in RF conditioning of the DTL, CCDTL and PIMS cavities. The behaviour in conditioning of these cavities strongly depends on the cavity type and assembly conditions. Examples of conditioning history and vacuum measurements before, during and after conditioning are discussed.

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THPLR061

Research on a Two-beam Type Drift Tube Linac

ion, heavy-ion, cavity, acceleration

989

L. Lu, C.X. Li, W. Ma, L.B. Shi, L.P. Sun, X.B. Xu, H.W. Zhao
IMP/CAS, Lanzhou, People's Republic of China
T.L. He
USTC/NSRL, Hefei, Anhui, People's Republic of China
L. Yang
USTC, Hefei, Anhui, People's Republic of China

The very high intense heavy-ion beam is a high attraction for heavy ion researches and heavy-ion applications, but it is limited by heavy-ion production of ion source and space-charge-effect in acceleration. There is one way, accelerating several heavy-ion beams in one cavity at same time and funneling them, which could achieve the acceleration of very high intense heavy-ion beam with existing ion source and accelerating technology. In this paper, we will introduce our designs, calculations and simulations of a 2-beam type drift tube linac.

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