LINAC2014 - List of Keywords (DTL)

Paper	Title	Other Keywords	Page
MOIOA02	Commissioning of the Low-Energy Part of Linac4	emittance, rfq, linac, solenoid	6
	A.M. Lombardi CERN, Geneva, Switzerland
	The Linac4 front-end (3MeV) was first commissioned in a dedicated test stand and then moved to its final position in the Linac4 tunnel. Accelerating cavities will be added progressively over two years to allow the characterisation of the beam with a dedicated measurement line at several energy stages (3,12,30,50, 100 and finally160MeV). This paper reports about the progress and the commissioning experience up to today.
	Slides MOIOA02 [5.339 MB]

MOPP036	Estimation of the Thermal Load and Signal Level of the ESS Wire Scanner	linac, detector, photon, cryomodule	137
	B. Cheymol ESS, Lund, Sweden
	The European Spallation Source (ESS), to be built in the south of Sweden, will use a 2 GeV superconducting linac to produce the worlds most powerful neutron source with a beam power of 5 MW. A number of wire scanners will be used to characterize the beam transverse profile. The design of the wire has to cope with the high power density of the beam and must satisfy the overall measurement robustness, accuracy and sensitivity for the commissioning and the regular retuning phase of the ESS linac. This paper describes the preliminary design of the wire scanner system in the normal conducing linac as well as in the superconducting linac.

MOPP037	Conceptual Design of the ESS DTL Faraday Cup	simulation, linac, cavity, beam-transport	140
	B. Cheymol, E. Lundh ESS, Lund, Sweden
	The DTL section of the ESS linac will accelerate the beam form 3.6 MeV to 90 MeV at a peak current of 62.5 mA. It is foreseen to install after each DTL tank a Faraday cup for beam current and the beam transmission measurements during retuning phase. An energy degrader will be positioned in front of the in order to perform a low resolution phase scan of the DTL tank before injecting the beam in the downstream structure. This paper describes the preliminary studies of the Faraday cup, mainly focus on the energy degrader.

MOPP039	Dynamics of Bunches Partially Chopped with the MEBT Chopper in the ESS Linac	linac, lattice, simulation, quadrupole	146
	R. Miyamoto, B. Cheymol, R. De Prisco, M. Eshraqi, A. Ponton, E. Sargsyan ESS, Lund, Sweden I. Bustinduy ESS Bilbao, Bilbao, Spain
	The front-end of a hadron linac typically has a transient time during turning on and off and bunches in the head and tail of a pulse from this period likely have wrong parameters and a risk to cause beam losses. A risk of losses must be avoided as possible in a high power machine so these bunches are removed with deflectors called choppers in the ESS Linac. From experiences of other machines, a rise time of a chopper as fast as one RF period (2.84~ns for ESS) is challenging to achieve and not necessarily needed with no ring to inject like ESS, and hence a 10~ns rise time is planned for a chopper in the medium energy beam transport of ESS. This, however, means that several bunches receive intermediate deflections and may propagate with large trajectory excursions. This paper studies dynamics of such partially chopped bunches in detail to ensure no significant loss is caused by them.

MOPP060	Status of the GSI Poststripper - HE-Linac	rfq, linac, ion, simulation	190
	S. Mickat, W.A. Barth, G. Clemente, X. Du, L. Groening, A. Orzhekhovskaya, B. Schlitt, H. Vormann, C. Xiao, S.G. Yaramyshev GSI, Darmstadt, Germany M. Droba, H. Hähnel, U. Ratzinger, R. Tiede IAP, Frankfurt am Main, Germany
	The High-Energy (HE) Linac is proposed to substitute the existing UNILAC post-stripper section. The post-stripper is an Alvarez DTL, which is in operation over four decades successfully. A quasi Front-to-End simulation along the UNILAC shows, that by taking future upgrade options into account already, with the existing Alvarez section the Fair requirements are not reached. Even by substituting the Alvarez section by the HE Linac the aim is not reached per se regarding the existing boundary conditions. Currently workpackages are defined together with the Institute of Applied Physics at Frankfurt University. Starting from the Ion sources to the SIS18 transfer channel every section is reinvestigated for improvements in beam quality and intensity.

MOPP062	Proposal of a Conventional Matching Section as an Alternative to the Existing HSI MEBT Superlens at GSI UNILAC	simulation, rfq, emittance, cavity	196
	H. Hähnel, U. Ratzinger, R. Tiede IAP, Frankfurt am Main, Germany
	We propose a new design for the HSI MEBT section at GSI UNILAC as part of the planned UNILAC upgrade. The existing MEBT section was designed in 1996 and based on a novel concept called the superlens* which uses a magnetic quadrupol doublet lens combined with a short RFQ cavity for transversal and longitudinal focusing. In 2009 the RFQ section in front of the MEBT was upgraded which led to significant changes in the RFQ output particle distribution. Recent LORASR simulations show that the superlens transmission decreases to 90% (related to 20.75 mA, U⁴⁺ at input). Moreover, the matching to the following IH-DTL is not ideal. This leads to further losses in the IH and to a decrease of the overall UNILAC efficiency. To reach the FAIR requirement of 18 mA U⁴⁺ current for the UNILAC with minimal losses and to provide more flexibility for varying current level operation, a new design based on two magnetic quadrupole triplet lenses and a 2-gap buncher is proposed. The design shows full transmission at 20.75 mA U⁴⁺ current and improved matching to the IH-DTL, leading to a drastic decrease of particle losses along the IH-DTL. * U. Ratzinger, R. Tiede, A New Matcher Type between RFQ and IH-DTL for the GSI High Current Heavy Ion Prestripper LINAC, Proc. LINAC96, Geneva, Switzerland, pp. 128-130
	Poster MOPP062 [9.440 MB]

MOPP067	Operation of the LINAC and the LINAC RF System for the Ion-Beam Therapy Center Heidelberg	ion, linac, operation, rfq	211
	E. Feldmeier, R. Cee, Th. Haberer HIT, Heidelberg, Germany
	The Heidelberg Ion Therapy Center HIT is in clinical operation since 2009. It is the first dedicated european particle accelerator for medical treatment. Its central location on the campus of the Heidelberg University Hospital fits perfectly in the clinical everyday life. The accelerator complex consists of a linear accelerator and a synchrotron and is designed for protons and carbon ions, but can also provide helium and oxygen ions. The LINAC, build in 2006, operates since 5 years in a 24/7 schema which leads to 60000 operating hours up to now. The performance with an availibility of better than 99% is much higher than expected and is caused by a solid design and a well planned and foresighted maintenance. Unavoidable failures during operation can be solved very fast with the on site experts for each section. The combination of personnel spare parts and permanent ongoing developments is very successful. An upgrade program for parts of the linac and also for the RF system is in planning to keep the uptime high and to improve the performance for further needs.

MOPP106	3D Mode Analysis of Full Tanks in Drift-Tube Linacs	linac, simulation, emittance, drift-tube-linac	300
	S.S. Kurennoy LANL, Los Alamos, New Mexico, USA
	Drift-tube linacs (DTLs) are usually designed and analyzed in axisymmetric approximation, cell by cell, using 2D codes such as Superfish and Parmila. We have developed 3D models of full DTL tanks with CST Studio to accurately calculate the tank modes, their sensitivity to post-coupler positions and tilts, tuner effects, and RF-coupler influence. Such models are important for the LANSCE DTL where each of four tanks contains tens of drift tubes and tank 2 has as much as 66 cells. We perform electromagnetic analysis of the DTL tank models using MicroWave Studio (MWS), mainly with eigensolvers but also in time domain. A similar approach has already been applied for thermal analysis of the LANSCE DTL but only with short tank models [1]. The full-tank analysis allows tuning the field profile of the operating mode and adjusting the frequencies of the neighboring modes within a realistic CST model. The MWS-calculated RF fields can be used for beam dynamics and thermal modeling. Here we present beam dynamics results for the LANSCE DTL from Particle Studio. [1] S.S. Kurennoy, LINAC08, Victoria, BC, 2008, p. 951.

MOPP107	Results from the Installation of a New 201 MHz RF System at LANSCE	cavity, electronics, controls, linac	303
	J.T.M. Lyles, C.L. Arnold, W.C. Barkley, J. Davis, A.C. Naranjo, M.S. Prokop, D. Rees, G. M. Sandoval, Jr. LANL, Los Alamos, New Mexico, USA D. Baca, R.E. Bratton, R.D. Summers Compa Industries, Inc., 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 is restoring the linac to it’s original high power capability after the power grid tube manufacturer could no longer provide triodes that could consistently meet our power requirements. High duty factor Diacrodes® now supply RF power to the largest DTL tank. These tetrodes reuse the existing infrastructure including water-cooling systems, coaxial transmission lines, high voltage power supplies and capacitor banks. The power amplifier system uses a combined pair of LANL-designed cavity amplifiers using the TH628L Diacrode® to produce as much as 3.5 MW peak and 420 kW of mean power. A digital low level RF control system was developed to complement these new linear amplifiers. Design and testing was completed in 2012, with commercialization following in 2013. The first installation is commissioned. The two remaining high power RF systems for tanks 3 and 4 will be replaced in subsequent years using a hybrid old/new RF system until the changeover is complete. Features and operating results of the replacement system are summarized, along with observations from the rapid-paced installation project.

TUIOB02	Beam Commissioning of the 100 MeV KOMAC Linac	proton, linac, operation, klystron	413
	Y.-S. Cho KAERI, Daejon, Republic of Korea
	Funding: This work was supported by the Ministry of Science, ICT & Future Planning of the Korean Government. The operation of the 100MeV proton linear accelerator for multipurpose application started in July, 2013 at KOMAC (Korea Multipurpose Accelerator Complex), KAERI (Korea Atomic Energy Research Institute). Also, the operation of the two beam lines, one is for 20MeV beam and the other for 100MeV beam, started in order to supply proton beams to users. The accumulated operation time was 2,290 hours and the proton beam was supplied to 937 samples in 2013. In addition to the beam service, the effort to increase the beam power is continuing in 2014. Beam commissioning and operation status of the linac will be presented in this talk.
	Slides TUIOB02 [7.200 MB]

TUIOB04	DTL Construction Status of CSNS Project	vacuum, linac, neutron, ion	423
	H.C. Liu, S. Fu, J. Peng, S. Wang IHEP, Beijing, People's Republic of China
	Linac of Chinese Spallation Neutron Source (CSNS) project is under construction. The ion source is tested and good performance of beam current is obtained. The low level RF tuning is underway of the RFQ and assembling of DTL will start soon. Not only the construction of hardware, but some commissioning software packages have been developed and tested.
	Slides TUIOB04 [4.772 MB]

TUPP025	Progress on ESS Medium Energy Beam Transport	linac, quadrupole, rfq, cavity	484
	I. Bustinduy, D. Fernandez-Cañoto, N. Garmendia, A. Ghiglino, O. González, P.J. González, Z. Izaola, I. Madariaga, M. Magan, L. Muguira, J.L. Muñoz, I. Rueda, F. Sordo, S. Varnasseri, R. Vivanco ESS Bilbao, Bilbao, Spain M. Eshraqi, R. Miyamoto, A. Ponton ESS, Lund, Sweden
	The considered versatile ESS MEBT is being designed to achieve four main goals: First, to contain a fast chopper and its correspondent beam dump, that could serve in the commissioning as well as in the ramp up phases. A detailed study of the chopper rise time effects on the loss budget will be presented. Second, to serve as a halo scraping section by means of various adjustable blades. Third, to measure the beam phase and proﬁle between the RFQ and the DTL, along with other beam monitors. And ﬁnally, to match the RFQ output beam characteristics to the DTL input both transversally and longitudinally. For this purpose a set of eleven quadrupoles is used to match the beam characteristics transversally, combined with three 352.2 MHz CCL type buncher cavities, which are used to adjust the beam in order to fulfil the required longitudinal parameters. A thorough study on the optimal input beam parameters will be discussed. Quadrupole design update will be presented along with new RF measurements over the buncher prototype. Finally, updated results will be presented on the chopper and beam-dump system.
	Poster TUPP025 [5.596 MB]

TUPP063	Improvements of the LORASR Code and their Impact on Current Beam Dynamics Designs	linac, proton, focusing, quadrupole	569
	R. Tiede, D. Mäder, N.F. Petry, H. Podlech, U. Ratzinger, C. Zhang IAP, Frankfurt am Main, Germany
	LORASR is a multi-particle tracking code optimized for the beam dynamics design of ‘Combined Zero Degree Structure (KONUS)’ lattices, which can benefit from an adapted input file structure and code architecture. Recent code developments focused on the implementation of tools for machine error studies and loss profile investigations, including also steering correction strategies. These tools are a stringent necessity for the design of high intensity linacs. Thus, the abilities of the present LORASR release allow performing a manifold of checks and optimizations before finalizing the layouts of KONUS-based or conventional linacs. Two representative examples are the MAX-MYRRHA Injector and the GSI FAIR Facility Proton Linac, both under development with strong participation of IAP, Frankfurt University. This paper presents the status of the LORASR code development with focus on the new features and illustrates the impact on current designs by examples taken from the above-mentioned projects.

TUPP089	Tuning and Field Stabilization of the CERN Linac4 Drift Tube Linac	linac, cavity, simulation, resonance	631
	M.R. Khalvati IPM, Tehran, Iran S. Ramberger CERN, Geneva, Switzerland
	The Drift Tube Linac (DTL) for the new linear accelerator Linac4 at CERN will accelerate H–beams of up to 40 mA average pulse current from 3 to 50 MeV. The structure consists of three cavities. The first cavity (Tank1) is a 3.9 m long tank containing 38 drift tubes, 10 fixed tuners, 2 movable tuners and 12 post-couplers, operating at a frequency of 352.2 MHz and an average accelerating field of 3.1 MV/m. This paper reports on the results and procedures used for the low–power tuning, stabilization and power coupler tuning carried out on the first Linac4 DTL tank. The upgrade of the bead pull measurement system and twists to the well-known tilt sensitivity technique are discussed.

TUPP094	Recent Progress of Beam Commissioning at J-PARC Linac	linac, operation, acceleration, cavity	646
	T. Maruta J-PARC, KEK & JAEA, Ibaraki-ken, Japan K. Futatsukawa, T. Miyao KEK, Ibaraki, Japan M. Ikegami FRIB, East Lansing, Michigan, USA Y. Liu KEK/JAEA, Ibaraki-Ken, Japan A. Miura, H. Sako JAEA/J-PARC, Tokai-mura, Japan
	We installed Annular-type Coupled Structure (ACS) linac in year 2013 in present linac downstream to extend the beam energy from 181 to 400 MeV. The beam commissioning had been conducted for one month in last December to January, and then we successfully extract 400 MeV beam. Whereas, we stably operate the linac at peak current of 15 mA, which is equivalent to 300 kW at the extraction of 3 GeV RCS, we observe unexpected residual radiations in ACS section. In this presentation, we review the recent progress in beam commissioning and beam loss study.

TUPP097	100-MeV Proton Beam Phase Measurement by Using Stripline BPM	linac, proton, simulation, coupling	656
	H.S. Kim, Y.-S. Cho, H.-J. Kwon KAERI, Daejon, Republic of Korea
	Funding: This work is supported by Ministry of Science, ICT & Future Planning of the Korean Government. In Korea Multipurpose Accelerator Complex (KOMAC), a 100-MeV proton linac, which is composed of a proton injector based on the microwave ion source, 3-MeV RFQ with a four-vane type and 100-MeV DTL with electromagnetic quadrupoles has been developed and currently provides the proton beam to users for various applications. To increase the beam power up to the design value, several improvements are required including the fine adjustment of the RF set-point during the operation. A stripline BPM is used for the beam phase measurement, where the pickup signals from four electrodes are combined by using the RF combiner, then mixed with 300 MHz LO reference signal resulting in 50 MHz IF signal which is processed by digital IQ demodulation method. In this paper, the details of the beam phase measurement setup and results will be presented.

WEIOA05	High Power RF Sources for the ESS RF Systems	klystron, linac, operation, rfq	756
	M. Jensen, G. Göransson, C. Marrelli, C. Martins, R. Montaño, A. Sunesson, R.A. Yogi, R. Zeng ESS, Lund, Sweden A.J. Johansson Lund University, Lund, Sweden
	The RF system for ESS will consist of around 150 high power RF sources and will deliver 125 MW peak power to the proton beam during the 2.86 ms pulse with an average power of 5 MW. The two RF frequencies, 352 and 704 MHz, the different power requirements along the linac and the sources currently available strongly influence the choice of RF technology. This talk will focus on the high power RF solutions for the main parts of the linac. We present an overview of the available technology along with the first test results of the main sources. Additionally, we will present the preliminary design of a new 1.2 MW multi-beam super power IOT being designed together with industry for the high beta section of the linac.
	Slides WEIOA05 [5.090 MB]

THPP027	Commissioning of the Linac4 Low Level RF and Future Plans	cavity, LLRF, linac, klystron	892
	P. Baudrenghien, J. Galindo, G. Hagmann, J. Noirjean, D. Stellfeld, D. Valuch CERN, Geneva, Switzerland
	Linac4 is a new 86-m long normal-conducting linear accelerator that will provide 160 MeV H⁻ to the CERN PS Booster (PSB), and replace the present 50 MeV proton Linac2. The Low Level RF (LLRF) system has to control the RFQ, two choppers, three bunching cavities, twenty two accelerating cavities and one debuncher in the transfer line to the PSB. To optimize the transfer into the 1 MHz PSB bucket, the machine includes fast choppers (synchronized with the PSB RF) and a voltage modulation of the last two cavities that will provide Longitudinal Painting for optimum filling. The commissioning in the tunnel with beam has started in October 2013. So far the part consisting of the RFQ, the three bunching cavities, and the first DTL is operational. The rest of the machine will be progressively commissioned till end 2015. The paper presents the LLRF system. First results from the commissioning (with a prototype regulation system) are shown and the more sophisticated algorithms under development are presented.

THPP036	CERN Linac4 Drift Tube Linac Manufacturing and Assembly	linac, vacuum, alignment, interface	923
	S. Ramberger, P. Bourquin, A. Cherif, Y. Cuvet, A. Dallocchio, G. Favre, J.-F. Fuchs, J.-M. Geisser, F. Gerigk, J.-M. Giguet, J. Hansen, M. Polini, S. Sgobba, N. Thaus, M. Vretenar CERN, Geneva, Switzerland
	The manufacturing of the Linac4 Drift Tube Linac (DTL) components has been completed and the assembly of the structures is in its final stages. 3 tanks of 3.9m, 7.3m, and 7.3m, designed to accelerate a 40mA average pulse current H–beam from 3 to 50MeV, are being assembled from 2, 4 and 4 segments of about 2.0m length, containing each from 22 drift tubes at the low energy end, down to only 6 at the high energy end. Due to its peculiar design avoiding adjustment mechanisms on the drift tube, tight tolerances have to be maintained in the production. This paper discusses the assembly stages that are used to achieve the tolerances over the full length of the structures. Metrology results on the assembled DTL Tank1 confirm the required precision.

THPP038	The Drift Tube Welding Assembly for the Linac4 Drift Tube Linac at CERN	linac, operation, drift-tube-linac, electron	929
	I. Sexton, A. Cherif, Y. Cuvet, G. Favre, J.-M. Geisser, S. Ramberger, S. Sgobba, T. Tardy CERN, Geneva, Switzerland F.M. Mirapeix DMP, Mendaro, Spain
	The fabrication of the Linac4 Drift Tube Linac (DTL) required the welding assembly of 10⁸ drift tubes (DT) which has been undertaken at the CERN workshop. The design of the DTL is particular in that it was purposely simplified to avoid any position adjustment mechanism for drift tubes in the tank. In consequence, drift tubes have been designed with tight tolerances and parts have been assembled with an optimised welding procedure. Two re-machining stages have been introduced in order to compensate for welding distortions. This paper discusses the various assembly stages with a view on the final precision that has been achieved.
	Poster THPP038 [8.665 MB]

THPP042	Error Study on the Normal Conducting ESS Linac	emittance, linac, rfq, quadrupole	942
	R. De Prisco, M. Eshraqi, R. Miyamoto, E. Sargsyan ESS, Lund, Sweden A.R. Karlsson Lund University, Lund, Sweden
	One of the preliminary, but important test to evaluate the robustness of the accelerator design is performing the statistical error study by introducing realistic tolerances on the machine components. In this paper the guidelines to define the tolerances and the correction system are summarized in order to validate the design. Firstly statistical studies have been performed in order to define the sensitivity to single errors and to fix the tolerances. Then all errors, within the previous defined tolerances, are applied with the correction system to evaluate the beam quality and to check if the system guarantees a radiologically safe operation.

THPP043	Benchmark of the Beam Dynamics Code DYNAC Using the ESS Proton Linac	linac, simulation, rfq, space-charge	945
	E. Tanke, R. De Prisco, M. Eshraqi, R. Miyamoto, A. Ponton, E. Sargsyan ESS, Lund, Sweden S. Valero CEA, Gif-sur-Yvette, France
	The beam dynamics code DYNAC is benchmarked using the ESS Proton Linac. Recent work on improvements in the code, including of the RFQ model, is discussed. The three space charge routines contained in DYNAC, including a 3D version, have remained unchanged. The code contains a numerical method, capable of simulating a multi-charge state ion beam in accelerating elements. In addition, protons, single charge state heavy ions and non-relativistic electrons in accelerating elements can be modeled using an analytical method. The benchmark will include comparisons of both methods with the beam dynamics models in use at ESS: TraceWin and Toutatis. As this analytical method used in DYNAC is fast, it is a prime candidate for use as an online beam simulation tool.

THPP044	ESS Normal Conducting Linac Status and Plans	linac, rfq, proton, vacuum	948
	A. Ponton, B. Cheymol, R. De Prisco, M. Eshraqi, R. Miyamoto, E. Sargsyan ESS, Lund, Sweden G. Bourdelle, M. Desmons, A. France, O. Piquet, B. Pottin CEA/DSM/IRFU, France I. Bustinduy, P.J. González, J.L. Muñoz, I. Rueda, F. Sordo ESS Bilbao, Bilbao, Spain L. Celona, S. Gammino, L. Neri INFN/LNS, Catania, Italy M. Comunian, F. Grespan, A. Pisent, C. R. Roncolato INFN/LNL, Legnaro (PD), Italy P. Mereu INFN-Torino, Torino, Italy
	The ESS Normal Conducting (NC) linac is composed of an ion source, a Low Energy Beam Transport line, a Radio Frequency Quarupole (RFQ), a Medium Energy Beam Transport Line (MEBT) and a Drift Tube Linac (DTL). It creates, bunches and accelerates the proton beam up to 90 MeV before injecting into the superconducting linac which will deliver a 5 MW beam onto the neutron production target. The construction of the NC linac is part of a broad collaboration involving experts of various Labs in Europe. The technical chalenges and the collaboration strategy for the NC linac will be presented.

THPP045	ESS Linac Beam Modes	rfq, linac, emittance, quadrupole	951
	E. Sargsyan, R. Miyamoto ESS, Lund, Sweden
	The ESS Linac will ultimately deliver 5 MW of beam power to the target with a long-pulse structure of 2.86 ms and 14 Hz repetition rate, which is essential for the production of long-wavelength neutrons [1]. Ten different beam power levels are requested for the operation. In order to preserve the required time structure of the beam, different beam power levels will be produced by reducing the beam current in ten regular steps using an iris with an adjustable aperture in the LEBT. Low current and low emittance beams may as well be useful for the beam commissioning of the Linac. This paper describes the generation and the beam dynamics of different beam modes in the ESS Linac.

THPP065	Acceleration of Intense Flat Beams in Periodic Lattices	emittance, focusing, space-charge, acceleration	1001
	L. Groening, C. Xiao GSI, Darmstadt, Germany I. Hofmann TEMF, TU Darmstadt, Darmstadt, Germany
	Recently a scheme for creation of flat ion beams from linacs has been proposed to increase the efficiency of multi-turn-injection. The proof of principle experiment shall be performed at GSI in Summer 2014. Since the scheme requires charge stripping, it may be necessary to perform the round-to-flat transformation prior to acceleration to the final energy of the linac. This requires preservation of the beam flatness during acceleration along the drift tube linac. This contribution is on simulations of acceleration of flat beams subject to considerable space charge tune depression. It is shown that the flatness can be preserved if the transverse tunes are properly chosen and if mis-match along inter-tank sections is minimized along the DTL.

THPP073	Cavity Excitation of the Chopped Beam at the J-PARC Linac	linac, pick-up, operation, injection	1023
	K. Futatsukawa KEK, Ibaraki, Japan
	In the J-PARC linac, the beam energy at the injection of the rapid-cycle synchrotron (RCS) was upgraded up to 400 MeV by the installation of 25 additional cavities, annular-ring coupled structure (ACS), in 2013. The initial frequency of RCS was shifted to 1.227 MHz because of the change the injection-beam velocity. At the linac, the beam is chopped as the comb-like structure with this frequency (intermediate-pulse) by the RF deflector. The component of this RCS frequency excited the PC1 mode of DTL2 and was the cause of the RF-control difficulty. Additionally, it could be confirmed that other chopping operations, which does not have specific intermediate-pulses for example, drove other modes. In this paper, I would like to introduce this phenomena and the counterplan as the RF control.

THPP086	ESS DTL Error Study	emittance, multipole, linac, dipole	1047
	M. Comunian, F. Grespan, A. Pisent INFN/LNL, Legnaro (PD), 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. The error study is decisive to define the DTL manufacturing tolerances and to evaluate its robustness. In this paper the DTL performances are shown.

THPP087	ESS DTL Design and Drift Tube Prototypes	linac, coupling, vacuum, quadrupole	1050
	F. Grespan, M. Comunian, A. Pisent, M. Poggi, C. R. Roncolato INFN/LNL, Legnaro (PD), Italy P. Mereu INFN-Torino, Torino, Italy
	The Drift Tube Linac (DTL) for the ESS accelerator will accelerate protons up to 62.5 mA average pulse current from 3.62 to 90 MeV. The 5 tanks composing the DTL are designed to operate at 352.2 MHz in pulses of 2.86 ms long with a repetition rate of 14 Hz. The accelerating field is around 3.1 MV/m, constant in each tank. Permanent magnet quadrupoles (PMQs) are used as focusing element in a FODO lattice. The empty drift tubes accommodate Electro Magnetic Dipoles (EMDs) and Beam Position Monitors (BPMs) in order to implement beam corrective schemes. A complete set of Drift Tubes is under construction that is BPM, EMD and PMQ types. These prototypes are aimed to validate the design with the involved integration issues of the various components, as well as the overall technological and assembly process. This paper presents the main mechanical choices and the status of the prototyping program of the Drift Tubes.

Paper

Title

Other Keywords

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MOIOA02

Commissioning of the Low-Energy Part of Linac4

emittance, rfq, linac, solenoid

6

A.M. Lombardi
CERN, Geneva, Switzerland

The Linac4 front-end (3MeV) was first commissioned in a dedicated test stand and then moved to its final position in the Linac4 tunnel. Accelerating cavities will be added progressively over two years to allow the characterisation of the beam with a dedicated measurement line at several energy stages (3,12,30,50, 100 and finally160MeV). This paper reports about the progress and the commissioning experience up to today.

Slides MOIOA02 [5.339 MB]

MOPP036

Estimation of the Thermal Load and Signal Level of the ESS Wire Scanner

linac, detector, photon, cryomodule

137

B. Cheymol
ESS, Lund, Sweden

The European Spallation Source (ESS), to be built in the south of Sweden, will use a 2 GeV superconducting linac to produce the worlds most powerful neutron source with a beam power of 5 MW. A number of wire scanners will be used to characterize the beam transverse profile. The design of the wire has to cope with the high power density of the beam and must satisfy the overall measurement robustness, accuracy and sensitivity for the commissioning and the regular retuning phase of the ESS linac. This paper describes the preliminary design of the wire scanner system in the normal conducing linac as well as in the superconducting linac.

MOPP037

Conceptual Design of the ESS DTL Faraday Cup

simulation, linac, cavity, beam-transport

140

B. Cheymol, E. Lundh
ESS, Lund, Sweden

The DTL section of the ESS linac will accelerate the beam form 3.6 MeV to 90 MeV at a peak current of 62.5 mA. It is foreseen to install after each DTL tank a Faraday cup for beam current and the beam transmission measurements during retuning phase. An energy degrader will be positioned in front of the in order to perform a low resolution phase scan of the DTL tank before injecting the beam in the downstream structure. This paper describes the preliminary studies of the Faraday cup, mainly focus on the energy degrader.

MOPP039

Dynamics of Bunches Partially Chopped with the MEBT Chopper in the ESS Linac

linac, lattice, simulation, quadrupole

146

R. Miyamoto, B. Cheymol, R. De Prisco, M. Eshraqi, A. Ponton, E. Sargsyan
ESS, Lund, Sweden
I. Bustinduy
ESS Bilbao, Bilbao, Spain

The front-end of a hadron linac typically has a transient time during turning on and off and bunches in the head and tail of a pulse from this period likely have wrong parameters and a risk to cause beam losses. A risk of losses must be avoided as possible in a high power machine so these bunches are removed with deflectors called choppers in the ESS Linac. From experiences of other machines, a rise time of a chopper as fast as one RF period (2.84~ns for ESS) is challenging to achieve and not necessarily needed with no ring to inject like ESS, and hence a 10~ns rise time is planned for a chopper in the medium energy beam transport of ESS. This, however, means that several bunches receive intermediate deflections and may propagate with large trajectory excursions. This paper studies dynamics of such partially chopped bunches in detail to ensure no significant loss is caused by them.

MOPP060

Status of the GSI Poststripper - HE-Linac

rfq, linac, ion, simulation

190

S. Mickat, W.A. Barth, G. Clemente, X. Du, L. Groening, A. Orzhekhovskaya, B. Schlitt, H. Vormann, C. Xiao, S.G. Yaramyshev
GSI, Darmstadt, Germany
M. Droba, H. Hähnel, U. Ratzinger, R. Tiede
IAP, Frankfurt am Main, Germany

The High-Energy (HE) Linac is proposed to substitute the existing UNILAC post-stripper section. The post-stripper is an Alvarez DTL, which is in operation over four decades successfully. A quasi Front-to-End simulation along the UNILAC shows, that by taking future upgrade options into account already, with the existing Alvarez section the Fair requirements are not reached. Even by substituting the Alvarez section by the HE Linac the aim is not reached per se regarding the existing boundary conditions. Currently workpackages are defined together with the Institute of Applied Physics at Frankfurt University. Starting from the Ion sources to the SIS18 transfer channel every section is reinvestigated for improvements in beam quality and intensity.

MOPP062

Proposal of a Conventional Matching Section as an Alternative to the Existing HSI MEBT Superlens at GSI UNILAC

simulation, rfq, emittance, cavity

196

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

We propose a new design for the HSI MEBT section at GSI UNILAC as part of the planned UNILAC upgrade. The existing MEBT section was designed in 1996 and based on a novel concept called the superlens* which uses a magnetic quadrupol doublet lens combined with a short RFQ cavity for transversal and longitudinal focusing. In 2009 the RFQ section in front of the MEBT was upgraded which led to significant changes in the RFQ output particle distribution. Recent LORASR simulations show that the superlens transmission decreases to 90% (related to 20.75 mA, U⁴⁺ at input). Moreover, the matching to the following IH-DTL is not ideal. This leads to further losses in the IH and to a decrease of the overall UNILAC efficiency. To reach the FAIR requirement of 18 mA U⁴⁺ current for the UNILAC with minimal losses and to provide more flexibility for varying current level operation, a new design based on two magnetic quadrupole triplet lenses and a 2-gap buncher is proposed. The design shows full transmission at 20.75 mA U⁴⁺ current and improved matching to the IH-DTL, leading to a drastic decrease of particle losses along the IH-DTL.
* U. Ratzinger, R. Tiede, A New Matcher Type between RFQ and IH-DTL for the GSI High Current Heavy Ion Prestripper LINAC, Proc. LINAC96, Geneva, Switzerland, pp. 128-130

Poster MOPP062 [9.440 MB]

MOPP067

Operation of the LINAC and the LINAC RF System for the Ion-Beam Therapy Center Heidelberg

ion, linac, operation, rfq

211

E. Feldmeier, R. Cee, Th. Haberer
HIT, Heidelberg, Germany

The Heidelberg Ion Therapy Center HIT is in clinical operation since 2009. It is the first dedicated european particle accelerator for medical treatment. Its central location on the campus of the Heidelberg University Hospital fits perfectly in the clinical everyday life. The accelerator complex consists of a linear accelerator and a synchrotron and is designed for protons and carbon ions, but can also provide helium and oxygen ions. The LINAC, build in 2006, operates since 5 years in a 24/7 schema which leads to 60000 operating hours up to now. The performance with an availibility of better than 99% is much higher than expected and is caused by a solid design and a well planned and foresighted maintenance. Unavoidable failures during operation can be solved very fast with the on site experts for each section. The combination of personnel spare parts and permanent ongoing developments is very successful. An upgrade program for parts of the linac and also for the RF system is in planning to keep the uptime high and to improve the performance for further needs.

MOPP106

3D Mode Analysis of Full Tanks in Drift-Tube Linacs

linac, simulation, emittance, drift-tube-linac

300

S.S. Kurennoy
LANL, Los Alamos, New Mexico, USA

Drift-tube linacs (DTLs) are usually designed and analyzed in axisymmetric approximation, cell by cell, using 2D codes such as Superfish and Parmila. We have developed 3D models of full DTL tanks with CST Studio to accurately calculate the tank modes, their sensitivity to post-coupler positions and tilts, tuner effects, and RF-coupler influence. Such models are important for the LANSCE DTL where each of four tanks contains tens of drift tubes and tank 2 has as much as 66 cells. We perform electromagnetic analysis of the DTL tank models using MicroWave Studio (MWS), mainly with eigensolvers but also in time domain. A similar approach has already been applied for thermal analysis of the LANSCE DTL but only with short tank models [1]. The full-tank analysis allows tuning the field profile of the operating mode and adjusting the frequencies of the neighboring modes within a realistic CST model. The MWS-calculated RF fields can be used for beam dynamics and thermal modeling. Here we present beam dynamics results for the LANSCE DTL from Particle Studio.
[1] S.S. Kurennoy, LINAC08, Victoria, BC, 2008, p. 951.

MOPP107

Results from the Installation of a New 201 MHz RF System at LANSCE

cavity, electronics, controls, linac

303

J.T.M. Lyles, C.L. Arnold, W.C. Barkley, J. Davis, A.C. Naranjo, M.S. Prokop, D. Rees, G. M. Sandoval, Jr.
LANL, Los Alamos, New Mexico, USA
D. Baca, R.E. Bratton, R.D. Summers
Compa Industries, Inc., 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 is restoring the linac to it’s original high power capability after the power grid tube manufacturer could no longer provide triodes that could consistently meet our power requirements. High duty factor Diacrodes® now supply RF power to the largest DTL tank. These tetrodes reuse the existing infrastructure including water-cooling systems, coaxial transmission lines, high voltage power supplies and capacitor banks. The power amplifier system uses a combined pair of LANL-designed cavity amplifiers using the TH628L Diacrode® to produce as much as 3.5 MW peak and 420 kW of mean power. A digital low level RF control system was developed to complement these new linear amplifiers. Design and testing was completed in 2012, with commercialization following in 2013. The first installation is commissioned. The two remaining high power RF systems for tanks 3 and 4 will be replaced in subsequent years using a hybrid old/new RF system until the changeover is complete. Features and operating results of the replacement system are summarized, along with observations from the rapid-paced installation project.

TUIOB02

Beam Commissioning of the 100 MeV KOMAC Linac

proton, linac, operation, klystron

413

Y.-S. Cho
KAERI, Daejon, Republic of Korea

Funding: This work was supported by the Ministry of Science, ICT & Future Planning of the Korean Government.
The operation of the 100MeV proton linear accelerator for multipurpose application started in July, 2013 at KOMAC (Korea Multipurpose Accelerator Complex), KAERI (Korea Atomic Energy Research Institute). Also, the operation of the two beam lines, one is for 20MeV beam and the other for 100MeV beam, started in order to supply proton beams to users. The accumulated operation time was 2,290 hours and the proton beam was supplied to 937 samples in 2013. In addition to the beam service, the effort to increase the beam power is continuing in 2014. Beam commissioning and operation status of the linac will be presented in this talk.

Slides TUIOB02 [7.200 MB]

TUIOB04

DTL Construction Status of CSNS Project

vacuum, linac, neutron, ion

423

H.C. Liu, S. Fu, J. Peng, S. Wang
IHEP, Beijing, People's Republic of China

Linac of Chinese Spallation Neutron Source (CSNS) project is under construction. The ion source is tested and good performance of beam current is obtained. The low level RF tuning is underway of the RFQ and assembling of DTL will start soon. Not only the construction of hardware, but some commissioning software packages have been developed and tested.

Slides TUIOB04 [4.772 MB]

TUPP025

Progress on ESS Medium Energy Beam Transport

linac, quadrupole, rfq, cavity

484

I. Bustinduy, D. Fernandez-Cañoto, N. Garmendia, A. Ghiglino, O. González, P.J. González, Z. Izaola, I. Madariaga, M. Magan, L. Muguira, J.L. Muñoz, I. Rueda, F. Sordo, S. Varnasseri, R. Vivanco
ESS Bilbao, Bilbao, Spain
M. Eshraqi, R. Miyamoto, A. Ponton
ESS, Lund, Sweden

The considered versatile ESS MEBT is being designed to achieve four main goals: First, to contain a fast chopper and its correspondent beam dump, that could serve in the commissioning as well as in the ramp up phases. A detailed study of the chopper rise time effects on the loss budget will be presented. Second, to serve as a halo scraping section by means of various adjustable blades. Third, to measure the beam phase and proﬁle between the RFQ and the DTL, along with other beam monitors. And ﬁnally, to match the RFQ output beam characteristics to the DTL input both transversally and longitudinally. For this purpose a set of eleven quadrupoles is used to match the beam characteristics transversally, combined with three 352.2 MHz CCL type buncher cavities, which are used to adjust the beam in order to fulfil the required longitudinal parameters. A thorough study on the optimal input beam parameters will be discussed. Quadrupole design update will be presented along with new RF measurements over the buncher prototype. Finally, updated results will be presented on the chopper and beam-dump system.

Poster TUPP025 [5.596 MB]

TUPP063

Improvements of the LORASR Code and their Impact on Current Beam Dynamics Designs

linac, proton, focusing, quadrupole

569

R. Tiede, D. Mäder, N.F. Petry, H. Podlech, U. Ratzinger, C. Zhang
IAP, Frankfurt am Main, Germany

LORASR is a multi-particle tracking code optimized for the beam dynamics design of ‘Combined Zero Degree Structure (KONUS)’ lattices, which can benefit from an adapted input file structure and code architecture. Recent code developments focused on the implementation of tools for machine error studies and loss profile investigations, including also steering correction strategies. These tools are a stringent necessity for the design of high intensity linacs. Thus, the abilities of the present LORASR release allow performing a manifold of checks and optimizations before finalizing the layouts of KONUS-based or conventional linacs. Two representative examples are the MAX-MYRRHA Injector and the GSI FAIR Facility Proton Linac, both under development with strong participation of IAP, Frankfurt University. This paper presents the status of the LORASR code development with focus on the new features and illustrates the impact on current designs by examples taken from the above-mentioned projects.

TUPP089

Tuning and Field Stabilization of the CERN Linac4 Drift Tube Linac

linac, cavity, simulation, resonance

631

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

The Drift Tube Linac (DTL) for the new linear accelerator Linac4 at CERN will accelerate H–beams of up to 40 mA average pulse current from 3 to 50 MeV. The structure consists of three cavities. The first cavity (Tank1) is a 3.9 m long tank containing 38 drift tubes, 10 fixed tuners, 2 movable tuners and 12 post-couplers, operating at a frequency of 352.2 MHz and an average accelerating field of 3.1 MV/m. This paper reports on the results and procedures used for the low–power tuning, stabilization and power coupler tuning carried out on the first Linac4 DTL tank. The upgrade of the bead pull measurement system and twists to the well-known tilt sensitivity technique are discussed.

TUPP094

Recent Progress of Beam Commissioning at J-PARC Linac

linac, operation, acceleration, cavity

646

T. Maruta
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
K. Futatsukawa, T. Miyao
KEK, Ibaraki, Japan
M. Ikegami
FRIB, East Lansing, Michigan, USA
Y. Liu
KEK/JAEA, Ibaraki-Ken, Japan
A. Miura, H. Sako
JAEA/J-PARC, Tokai-mura, Japan

We installed Annular-type Coupled Structure (ACS) linac in year 2013 in present linac downstream to extend the beam energy from 181 to 400 MeV. The beam commissioning had been conducted for one month in last December to January, and then we successfully extract 400 MeV beam. Whereas, we stably operate the linac at peak current of 15 mA, which is equivalent to 300 kW at the extraction of 3 GeV RCS, we observe unexpected residual radiations in ACS section. In this presentation, we review the recent progress in beam commissioning and beam loss study.

TUPP097

100-MeV Proton Beam Phase Measurement by Using Stripline BPM

linac, proton, simulation, coupling

656

H.S. Kim, Y.-S. Cho, H.-J. Kwon
KAERI, Daejon, Republic of Korea

Funding: This work is supported by Ministry of Science, ICT & Future Planning of the Korean Government.
In Korea Multipurpose Accelerator Complex (KOMAC), a 100-MeV proton linac, which is composed of a proton injector based on the microwave ion source, 3-MeV RFQ with a four-vane type and 100-MeV DTL with electromagnetic quadrupoles has been developed and currently provides the proton beam to users for various applications. To increase the beam power up to the design value, several improvements are required including the fine adjustment of the RF set-point during the operation. A stripline BPM is used for the beam phase measurement, where the pickup signals from four electrodes are combined by using the RF combiner, then mixed with 300 MHz LO reference signal resulting in 50 MHz IF signal which is processed by digital IQ demodulation method. In this paper, the details of the beam phase measurement setup and results will be presented.

WEIOA05

High Power RF Sources for the ESS RF Systems

klystron, linac, operation, rfq

756

M. Jensen, G. Göransson, C. Marrelli, C. Martins, R. Montaño, A. Sunesson, R.A. Yogi, R. Zeng
ESS, Lund, Sweden
A.J. Johansson
Lund University, Lund, Sweden

The RF system for ESS will consist of around 150 high power RF sources and will deliver 125 MW peak power to the proton beam during the 2.86 ms pulse with an average power of 5 MW. The two RF frequencies, 352 and 704 MHz, the different power requirements along the linac and the sources currently available strongly influence the choice of RF technology. This talk will focus on the high power RF solutions for the main parts of the linac. We present an overview of the available technology along with the first test results of the main sources. Additionally, we will present the preliminary design of a new 1.2 MW multi-beam super power IOT being designed together with industry for the high beta section of the linac.

Slides WEIOA05 [5.090 MB]

THPP027

Commissioning of the Linac4 Low Level RF and Future Plans

cavity, LLRF, linac, klystron

892

P. Baudrenghien, J. Galindo, G. Hagmann, J. Noirjean, D. Stellfeld, D. Valuch
CERN, Geneva, Switzerland

Linac4 is a new 86-m long normal-conducting linear accelerator that will provide 160 MeV H⁻ to the CERN PS Booster (PSB), and replace the present 50 MeV proton Linac2. The Low Level RF (LLRF) system has to control the RFQ, two choppers, three bunching cavities, twenty two accelerating cavities and one debuncher in the transfer line to the PSB. To optimize the transfer into the 1 MHz PSB bucket, the machine includes fast choppers (synchronized with the PSB RF) and a voltage modulation of the last two cavities that will provide Longitudinal Painting for optimum filling. The commissioning in the tunnel with beam has started in October 2013. So far the part consisting of the RFQ, the three bunching cavities, and the first DTL is operational. The rest of the machine will be progressively commissioned till end 2015. The paper presents the LLRF system. First results from the commissioning (with a prototype regulation system) are shown and the more sophisticated algorithms under development are presented.

THPP036

CERN Linac4 Drift Tube Linac Manufacturing and Assembly

linac, vacuum, alignment, interface

923

S. Ramberger, P. Bourquin, A. Cherif, Y. Cuvet, A. Dallocchio, G. Favre, J.-F. Fuchs, J.-M. Geisser, F. Gerigk, J.-M. Giguet, J. Hansen, M. Polini, S. Sgobba, N. Thaus, M. Vretenar
CERN, Geneva, Switzerland

The manufacturing of the Linac4 Drift Tube Linac (DTL) components has been completed and the assembly of the structures is in its final stages. 3 tanks of 3.9m, 7.3m, and 7.3m, designed to accelerate a 40mA average pulse current H–beam from 3 to 50MeV, are being assembled from 2, 4 and 4 segments of about 2.0m length, containing each from 22 drift tubes at the low energy end, down to only 6 at the high energy end. Due to its peculiar design avoiding adjustment mechanisms on the drift tube, tight tolerances have to be maintained in the production. This paper discusses the assembly stages that are used to achieve the tolerances over the full length of the structures. Metrology results on the assembled DTL Tank1 confirm the required precision.

THPP038

The Drift Tube Welding Assembly for the Linac4 Drift Tube Linac at CERN

linac, operation, drift-tube-linac, electron

929

I. Sexton, A. Cherif, Y. Cuvet, G. Favre, J.-M. Geisser, S. Ramberger, S. Sgobba, T. Tardy
CERN, Geneva, Switzerland
F.M. Mirapeix
DMP, Mendaro, Spain

The fabrication of the Linac4 Drift Tube Linac (DTL) required the welding assembly of 10⁸ drift tubes (DT) which has been undertaken at the CERN workshop. The design of the DTL is particular in that it was purposely simplified to avoid any position adjustment mechanism for drift tubes in the tank. In consequence, drift tubes have been designed with tight tolerances and parts have been assembled with an optimised welding procedure. Two re-machining stages have been introduced in order to compensate for welding distortions. This paper discusses the various assembly stages with a view on the final precision that has been achieved.

Poster THPP038 [8.665 MB]

THPP042

Error Study on the Normal Conducting ESS Linac

emittance, linac, rfq, quadrupole

942

R. De Prisco, M. Eshraqi, R. Miyamoto, E. Sargsyan
ESS, Lund, Sweden
A.R. Karlsson
Lund University, Lund, Sweden

One of the preliminary, but important test to evaluate the robustness of the accelerator design is performing the statistical error study by introducing realistic tolerances on the machine components. In this paper the guidelines to define the tolerances and the correction system are summarized in order to validate the design. Firstly statistical studies have been performed in order to define the sensitivity to single errors and to fix the tolerances. Then all errors, within the previous defined tolerances, are applied with the correction system to evaluate the beam quality and to check if the system guarantees a radiologically safe operation.

THPP043

Benchmark of the Beam Dynamics Code DYNAC Using the ESS Proton Linac

linac, simulation, rfq, space-charge

945

E. Tanke, R. De Prisco, M. Eshraqi, R. Miyamoto, A. Ponton, E. Sargsyan
ESS, Lund, Sweden
S. Valero
CEA, Gif-sur-Yvette, France

The beam dynamics code DYNAC is benchmarked using the ESS Proton Linac. Recent work on improvements in the code, including of the RFQ model, is discussed. The three space charge routines contained in DYNAC, including a 3D version, have remained unchanged. The code contains a numerical method, capable of simulating a multi-charge state ion beam in accelerating elements. In addition, protons, single charge state heavy ions and non-relativistic electrons in accelerating elements can be modeled using an analytical method. The benchmark will include comparisons of both methods with the beam dynamics models in use at ESS: TraceWin and Toutatis. As this analytical method used in DYNAC is fast, it is a prime candidate for use as an online beam simulation tool.

THPP044

ESS Normal Conducting Linac Status and Plans

linac, rfq, proton, vacuum

948

A. Ponton, B. Cheymol, R. De Prisco, M. Eshraqi, R. Miyamoto, E. Sargsyan
ESS, Lund, Sweden
G. Bourdelle, M. Desmons, A. France, O. Piquet, B. Pottin
CEA/DSM/IRFU, France
I. Bustinduy, P.J. González, J.L. Muñoz, I. Rueda, F. Sordo
ESS Bilbao, Bilbao, Spain
L. Celona, S. Gammino, L. Neri
INFN/LNS, Catania, Italy
M. Comunian, F. Grespan, A. Pisent, C. R. Roncolato
INFN/LNL, Legnaro (PD), Italy
P. Mereu
INFN-Torino, Torino, Italy

The ESS Normal Conducting (NC) linac is composed of an ion source, a Low Energy Beam Transport line, a Radio Frequency Quarupole (RFQ), a Medium Energy Beam Transport Line (MEBT) and a Drift Tube Linac (DTL). It creates, bunches and accelerates the proton beam up to 90 MeV before injecting into the superconducting linac which will deliver a 5 MW beam onto the neutron production target. The construction of the NC linac is part of a broad collaboration involving experts of various Labs in Europe. The technical chalenges and the collaboration strategy for the NC linac will be presented.

THPP045

ESS Linac Beam Modes

rfq, linac, emittance, quadrupole

951

E. Sargsyan, R. Miyamoto
ESS, Lund, Sweden

The ESS Linac will ultimately deliver 5 MW of beam power to the target with a long-pulse structure of 2.86 ms and 14 Hz repetition rate, which is essential for the production of long-wavelength neutrons [1]. Ten different beam power levels are requested for the operation. In order to preserve the required time structure of the beam, different beam power levels will be produced by reducing the beam current in ten regular steps using an iris with an adjustable aperture in the LEBT. Low current and low emittance beams may as well be useful for the beam commissioning of the Linac. This paper describes the generation and the beam dynamics of different beam modes in the ESS Linac.

THPP065

Acceleration of Intense Flat Beams in Periodic Lattices

emittance, focusing, space-charge, acceleration

1001

L. Groening, C. Xiao
GSI, Darmstadt, Germany
I. Hofmann
TEMF, TU Darmstadt, Darmstadt, Germany

Recently a scheme for creation of flat ion beams from linacs has been proposed to increase the efficiency of multi-turn-injection. The proof of principle experiment shall be performed at GSI in Summer 2014. Since the scheme requires charge stripping, it may be necessary to perform the round-to-flat transformation prior to acceleration to the final energy of the linac. This requires preservation of the beam flatness during acceleration along the drift tube linac. This contribution is on simulations of acceleration of flat beams subject to considerable space charge tune depression. It is shown that the flatness can be preserved if the transverse tunes are properly chosen and if mis-match along inter-tank sections is minimized along the DTL.

THPP073

Cavity Excitation of the Chopped Beam at the J-PARC Linac

linac, pick-up, operation, injection

1023

K. Futatsukawa
KEK, Ibaraki, Japan

In the J-PARC linac, the beam energy at the injection of the rapid-cycle synchrotron (RCS) was upgraded up to 400 MeV by the installation of 25 additional cavities, annular-ring coupled structure (ACS), in 2013. The initial frequency of RCS was shifted to 1.227 MHz because of the change the injection-beam velocity. At the linac, the beam is chopped as the comb-like structure with this frequency (intermediate-pulse) by the RF deflector. The component of this RCS frequency excited the PC1 mode of DTL2 and was the cause of the RF-control difficulty. Additionally, it could be confirmed that other chopping operations, which does not have specific intermediate-pulses for example, drove other modes. In this paper, I would like to introduce this phenomena and the counterplan as the RF control.

THPP086

ESS DTL Error Study

emittance, multipole, linac, dipole

1047

M. Comunian, F. Grespan, A. Pisent
INFN/LNL, Legnaro (PD), 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. The error study is decisive to define the DTL manufacturing tolerances and to evaluate its robustness. In this paper the DTL performances are shown.

THPP087

ESS DTL Design and Drift Tube Prototypes

linac, coupling, vacuum, quadrupole

1050

F. Grespan, M. Comunian, A. Pisent, M. Poggi, C. R. Roncolato
INFN/LNL, Legnaro (PD), Italy
P. Mereu
INFN-Torino, Torino, Italy

The Drift Tube Linac (DTL) for the ESS accelerator will accelerate protons up to 62.5 mA average pulse current from 3.62 to 90 MeV. The 5 tanks composing the DTL are designed to operate at 352.2 MHz in pulses of 2.86 ms long with a repetition rate of 14 Hz. The accelerating field is around 3.1 MV/m, constant in each tank. Permanent magnet quadrupoles (PMQs) are used as focusing element in a FODO lattice. The empty drift tubes accommodate Electro Magnetic Dipoles (EMDs) and Beam Position Monitors (BPMs) in order to implement beam corrective schemes. A complete set of Drift Tubes is under construction that is BPM, EMD and PMQ types. These prototypes are aimed to validate the design with the involved integration issues of the various components, as well as the overall technological and assembly process. This paper presents the main mechanical choices and the status of the prototyping program of the Drift Tubes.