LINAC2012 - List of Keywords (simulation)

Paper	Title	Other Keywords	Page
SUPB003	Feasibility Study of Short Pulse Mode Operation for Multi-turn ERL Light Source	linac, emittance, undulator, acceleration	4
	T. Atkinson, A.V. Bondarenko, A.N. Matveenko, Y. Petenev HZB, Berlin, Germany
	The optics and simulation group at HZB are designing Germany’s future light source. Based on the emerging Energy Recovery Linac super conducting technology, the Femto-Science-Factory (FSF) will provide its users with ultra-bright photons of Angstrom wavelength at 6 GeV. The FSF is intended to be a multi-user facility and offer a wide variety of operation modes. A low emittance ~0.1 μm rad mode will operate in conjunction with a short-pulse ~10 fs mode. This paper highlights the physical limitations when trying to offer interchangeable modes and preserve beam high quality.

SUPB006	Study of Beam-Based Alignment for Shanghai Soft X-Ray FEL Facility	linac, emittance, alignment, FEL	10
	D. Gu, Q. Gu, D. Huang, M. Zhang, M.H. Zhao SINAP, Shanghai, People's Republic of China
	In linear accelerators, dispersion caused by quadrupole misalignment and transverse wake-field effect caused by alignment errors of accelerate structures will lead to a significant emittance growth. There are more stringent restrictions on SXFEL, the traditional optical alignment can no longer meet its requirements, but the Beam-Based Alignment(BBA) method allows more precise alignment, further reduce the Linac errors to meet SXFEL requirements .In undulator sections, orbit changes are not only caused by misalignments of quadrupole magnet position ,but also the errors of undulator magnetic. In order to achieve alignment accuracy over longer distance, we measuring BPM data under different conditions and using SVD algorithm for calculation and analysis, we can get the quadrupole magnet errors and BPM offset. With the method above, software based on MATLAB has been designed and compared the results with other software.

SUPB007	On-Line Dispersion Free Steering for the Main Linac of CLIC	emittance, ground-motion, feedback, linac	13
	J. Pfingstner, D. Schulte CERN, Geneva, Switzerland
	For future linear colliders as well as for light sources, ground motion effects are a severe problem for the accelerator performance. After a few minutes, orbit feedback systems are not sufficient to mitigate all ground motion effects and additional long term methods will have to be deployed. In this paper, the long term ground motion effects in the main linac of the Compact Linear Collider (CLIC) are analysed via simulation studies. The primary growth of the projected emittance is identified to originate from chromatic dilutions due to dispersive beam orbits. To counter this effect, an on-line identification algorithm is applied to measure the dispersion parasitically. This dispersion estimate is used to correct the beam orbit with an iterative dispersion free steering algorithm. The presented results are not only of interest for the CLIC project, but for all linacs in which the dispersive orbit has to be corrected over time.

SUPB011	Computational Model Analysis for Experimental Observation of Optical Current Noise Suppression Below the Shot-noise Limit	plasma, electron, linac, beam-transport	25
	A. Nause, A. Gover University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel
	Funding: We acknowledge support of the Israel Science Foundation grant We report first demonstration of optical frequency current shot-noise suppression in a relativistic e-beam. This process is made possible by collective Coulomb interaction between the electrons of a cold intense beam during beam drift, and is essentially a process of longitudinal beam-plasma oscillation [1]. Suppression of beam current noise below the classical “shot-noise” level has been known in the microwave tubes art [2]. This is the first time that it is demonstrated in the optical regime. We predict that the scheme can be extended to the XUV and possibly to shorter wavelengths with further development of technology. The fundamental current shot-noise determines the level of incoherent spontaneous radiation emission from electron-beam optical radiation sources and SASE-FELs [3]. Suppressing shot-noise would make it possible to attain spontaneous emission sub-radiance [4] and surpass the classical coherence limits of seed-injected FELs. The effect was demonstrated by measuring sub-linear growth as a function of current of the OTR Radiation. This finding indicates that the beam charge homogenizes due to the collective interaction, and its distribution becomes sub-Poissonian. [1] A. Gover, E. Dyunin, PRL, 102, 154801, 2009 [2] H. Haus, N. Robinson, Proc. IRE, 43, 981 (1955) [3] P. Emma, et al , Nature Photonics 4, 641 (2010) [4] A. Dicke, Phys. Rev. 93, 99 (1954)

SUPB013	The Beam Commissioning Plan of Injector II in C-ADS	rfq, cavity, proton, diagnostics	32
	Z.J. Wang, Y. He, H. Jia, C. Li, S.H. Liu, W. Wu, X.B. Xu, B. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	The design work of the Injector II, which is 10 MeV proton linac, in C-ADS project is being finished and some key elements are being fabricated. Now it is necessary to definite the operation mode of beam commissioning, including the selection of the beam current, pulse length and repetition frequency. Also the beam commissions plan should be specified. The beam commissions procedures is simulated with t-mode code GPT. In this paper, the general beam commissioning plan of Injector II in CIADS and simulation results of commissions procedures are presented.

SUPB014	RF Setup of the MedAustron RFQ	rfq, resonance, ion, pick-up	35
	B. Koubek, A. Schempp, J.S. Schmidt IAP, Frankfurt am Main, Germany J. Haeuser Kress GmbH, Biebergemuend, Germany
	A Radio Frequency Quadrupole (RFQ) was built for the injector of the cancer treatment facility MedAuston in Austria. For the RF design simulations were performed using CST Microwave Studio and the structure was manufactured by Firma Kress in Biebergemuend, Germany. The simulations and the RF setup of the delivered RFQ are presented in this paper.

SUPB016	RFQ With Improved Energy Gain	rfq, acceleration, ion, emittance	41
	A. Kolomiets ITEP, Moscow, Russia A.S. Plastun MEPhI, Moscow, Russia
	RFQ structure is practically only one choice for using in front ends of ion linacs for acceleration up to energy about 3 MeV. This limit is due to its relatively low acceleration efficiency. However it isn’t intrinsic feature of RFQ principle. It is defined only by vane geometry of conventional RFQ structure with sinusoidal modulation of vanes. The paper presents results of analysis RFQ with modified vane geometries that allow to improve acceleration efficiency. RFQ with modified vanes was used for design second section of heavy ion injector of TWAC for acceleration of ions with Z/A = 0.33 up to 7 MeV/u.

SUPB017	Tuning Studies on 4-rod-RFQs	rfq, linac, resonance, coupling	44
	J.S. Schmidt, B. Klump, B. Koubek, A. Schempp IAP, Frankfurt am Main, Germany
	A NI LabVIEW based Tuning Software has been devel- oped to structure the tuning process of 4-rod Radio Fre- quency Quadrupole s (RFQs). Its results are compared to measurement data of 4-rod RFQs in different frequency ranges. For the optimization of RFQ design parameters, a certain voltage distribution along the electrodes of an RFQ is assumed. Therefore an accurate tuning of the voltage distribution is very important for the beam dynamic prop- erties of an RFQ. A variation can lead to particle losses and reduced beam quality especially at higher frequencies. Our electrode design usually implies a constant longitudi- nal voltage distribution. For its adjustment tuning plates are used between the stems of the 4-rod-RFQ. These pre- dictions are based, in contrast to other simulations, on mea- surements to define the characteristics of the RFQ as it was build - not depending on assumptions of the design. This will lead to a totally new structured process of tuning 4- rod-RFQs in a broad range of frequencies by using the pre- dictions of a software. The results of these studies are pre- sented in this paper.

SUPB018	Studies of Parasitic Cavity Modes for Proposed ESS Linac Lattices	linac, cavity, proton, lattice	47
	R. Ainsworth Royal Holloway, University of London, Surrey, United Kingdom S. Molloy ESS, Lund, Sweden
	The European Spallation Source (ESS) planned for construction in Lund, Sweden, will be the worlds most intense source of pulsed neutrons. The neutrons will be generated by the collision of a 2.5 GeV proton beam with a heavy-metal target. The superconducting section of the proton linac is split into three different types of cavities, and a question for the lattice designers is at which points in the beamline these splits should occur. This note studies various proposed designs for the ESS lattice from the point of view of the effect on the beam dynamics of the parasitic cavity modes lying close in frequency to the fundamental accelerating mode. Each linac design is characterised by the initial kinetic energy of the beam, as well as by the velocity of the beam at each of the points at which the cavity style changes. The scale of the phase-space disruption of the proton pulse is discussed, and some general conclusions for lattice designers are stated.

SUPB019	The Multipacting Simulation for the New-Shaped QWR using TRACK3P	cavity, accelerating-gradient, electron, niobium	50
	C. Zhang, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, S.H. Zhang, S.X. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	In order to improve the electro-magnetic performance of the quarter wave resonator, a new-shaped cavity with an elliptical cylinder outer conductor has been proposed. This novel cavity design can provide much lower peak surface magnetic field and much higher Ra/Q0 and G. The Multipacting simulation has been done for this new QWR cavity using ACE3P/TRACK3P code, in this paper the simulation results will be presented and analyzed.

SUPB020	Structural Analysis of the New-Shaped QWR for HIAF in IMP	cavity, superconducting-cavity, SRF, controls	53
	C. Zhang, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, Y.Z. Yang, W.M. Yue, S.H. Zhang, S.X. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China M.H. Xu IHEP, Beijing, People's Republic of China
	Since the QWR cavity is very successful for the operation with frequency of 48 to 160 MHz and beta value of 0.001 to 0.2, a new-shaped QWR is being designed for the low energy superconducting section of HIAF in the Institute of Modern Physics. The cavity will work at 81.25 MHz and \beta of 0.085，with a elliptical cylinder outer conductor to better its electro-magnetic performance and keep limited accelerating space. Structural design is an important aspect of the overall cavity implementation, and in order to minimize the frequency shift of the cavity due to the helium bath pressure fluctuations, the Lorentz force and microphonic excitation, stiffening elements have to be applied. In this paper, structural analyses of the new-shaped QWR are presented and stiffening methods are explored.

SUPB022	First Measurements on the 325 MHz Superconducting CH Cavity	cavity, controls, linac, coupling	56
	M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany M. Amberg HIM, Mainz, Germany W.A. Barth, S. Mickat GSI, Darmstadt, Germany M. Pekeler RI Research Instruments GmbH, Bergisch Gladbach, Germany
	Funding: Work supported by HIM, GSI, BMBF Contr. No. 06FY161I At the Institute for Applied Physics (IAP), Frankfurt University, a superconducting 325 MHz CH-Cavity has been designed and built. This 7-cell cavity has a geometrical \beta of 0.16 corresponding to a beam energy of 11.4 AMeV. The design gradient is 5 MV/m. Novel features of this resonator are a compact design, low peak fields, easy surface processing and power coupling. Furthermore a new tuning system based on bellow tuners inside the resonator will control the frequency during operation. After successful rf tests in Frankfurt the cavity will be tested with a 10 mA, 11.4 AMeV beam delivered by the GSI UNILAC. In this paper first measurements and corresponding simulations will be presented.

SUPB023	Status of the Superconducting CW Demonstrator for GSI	cavity, linac, solenoid, cryogenics	59
	F.D. Dziuba, M. Amberg, M. Busch, H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany K. Aulenbacher IKP, Mainz, Germany W.A. Barth, S. Mickat GSI, Darmstadt, Germany
	Funding: Helmholtz Institut Mainz (HIM), GSI, BMBF Contr. No. 06FY7102 Since the existing UNILAC at GSI will be used as an injector for the FAIR facility a new superconducting (sc) continous wave (cw) LINAC is highly requested by a broad community of future users to fulfil the requirements of nuclear chemistry, especially in the research field of Super Heavy Elements (SHE). This LINAC is under design in collaboration with the Institute for Applied Physics (IAP) of Frankfurt University, GSI and the Helmholtz Institut Mainz (HIM). It will consist of 9 sc Crossbar-H-mode (CH) cavities operated at 217 MHz which provide an energy up to 7.3 AMeV. Currently, a prototype of the cw LINAC is under development. This demonstrator comprises the first sc CH cavity of the LINAC embedded between two sc solenoids mounted in a horizontal cryomodule. One important milestone of the project will be a full performance test of the demonstrator by injecting and accelerating a beam from the GSI High Charge State Injector (HLI) in 2014. The status of the demonstrator is presented.

SUPB024	Development of Permanent Magnet Focusing System for Klystrons	klystron, focusing, permanent-magnet, cathode	62
	Y. Fuwa, Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan S. Fukuda, S. Michizono KEK, Ibaraki, Japan
	The Distributed RF System (DRFS) for the International Linear Collider (ILC) requires thousands of klystrons. The failure rate of the power supply for solenoid focusing coil of each klystron may be a critical issue for a regular operation of the ILC. A permanent magnet beam focusing system can increase reliability and eliminate their power consumption. Since the required magnetic field is not high in this system, inexpensive anisotropic ferrite magnets can be used instead of magnets containing rare earth materials. In order to prove its feasibility, a test model of a permanent magnet focusing beam system is constructed and a power test of the klystron for DRFS with this model is under preparation. The results of magnetic field distribution measurement and the power test will be presented.

SUPB026	Multipacting Analysis of High-velocity Superconducting Spoke Resonators	electron, cavity, site, superconductivity	68
	C.S. Hopper, J.R. Delayen ODU, Norfolk, Virginia, USA
	Some of the advantages of superconducting spoke cavities are currently being investigated for the high-velocity regime. When determining a final, optimized geometry, one must consider the possible limiting effects multipacting could have on the cavity. We report on the results of analytical calculations and numerical simulations of multipacting electrons in superconducting spoke cavities and methods for reducing their impact.

SUPB027	Mechanical Study of the First Superconducting Half-wave Resonator for Injector II of CADS Project	cavity, HOM, controls, cryomodule	71
	S. He, Y. He, S.C. Huang, F.F. Wang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	Funding: This work is Supported by the National Natural Science Foundation of China (Grant Agreement 91026001) Within the framework of the China Accelerator-Driven Sub-critical Systems (CADS) project, Institute of Modern Physics (IMP) Chinese Academic of Sciences has proposed a 162.5 MHz Half-Wave Resonator (HWR) Superconducting cavity for low energy section (β=0.09) of high power proton linear accelerators as a new injector II for CIADS. For the geometrical design of superconducting cavities structure mechanical simulations are essential to predict mechanical eigenmodes and the deformation of the cavity walls due to bath pressure effects and the cavity cool-down. Additionally, the tuning analysis has been investigated to control the frequency against microphonics and Lorentz force detuning. Therefore, several RF, static structure, thermal and modal analysis with a three-dimensional Finite-Element Method (FEM) code Traditional ANSYS have been performed.

SUPB028	The Superconducting CH Cavity Development in IMP*	cavity, linac, niobium, resonance	74
	M.X. Xu, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, Z.J. Wang, J.W. Xia, Y.Z. Yang, W.M. Yue, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	Funding: Work supported by 91026001 Nature Science Foundation of China The Cross-Bar H-type (CH) cavity is a multi-gap drift tube structure operated in the H21 mode [1]. The Institute of Modern Physics (IMP) has been doing research and development on this type of superconducting CH cavity which can work at the C-ADS (accelerator driver sub-critical system of China). A new geometry CH cavity has been proposed which have smaller radius. It’s suitable in fabrication, and it’s can reduce cost too .Detailed numerical simulations with CST MicroWave Studio have been performed. An overall surface reduction of 30% against the old structure seems feasible. A copper model CH cavity is being fabrication for validating the simulations and the procedure of fabricating niobium cavity.

SUPB032	The C-band RF Pulse Compression for Soft XFEL at SINAP	cavity, coupling, klystron, free-electron-laser	83
	C.P. Wang, Q. Gu, Z.T. Zhao SINAP, Shanghai, People's Republic of China
	A compact soft X-ray free electron laser facility is presently being constructed at shanghai institute of applied physics (SINAP), Chinese academy of science in 2012 and will be accomplished in 2014. This facility requires a compact linac with a high-gradient accelerating structure for a limited overall length less than 230 m. The c-band technology which is already used in KEK/Spring-8 linear accelerator is a good compromise for this compact facility and a c-and traveling-wave accelerating structure was already fabricated and tested at SINAP, so a c-band pulse compression will be required. AND a SLED type RF compression scheme is proposed for the C-band RF system of the soft XFEL and this scheme uses TE0.1.15 mode energy storage cavity for high Q-energy storage. The C-band pulse compression under development at SINAP has a high power gain about 3.1 and it is designed to compress the pulse width from 2.5 μs to 0.5 μs and multiply the input RF power of 50 MW to generate 160 MW peak RF power, and the coupling coefficient will be 8.5. It has three components: 3 dB coupler, mode convertors and the resonant cavities.

MO3A04	Accelerator/Decelerator of Slow Neutrons	neutron, focusing, controls, dipole	133
	M. Kitaguchi Kyoto University, Research Reactor Institute, Osaka, Japan Y. Arimoto, H.M. Shimizu KEK, Ibaraki, Japan P.W. Geltenbort ILL, Grenoble, France S. Imajo Kyoto University, Kyoto, Japan Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan Y. Seki RIKEN Nishina Center, Wako, Japan T. Yoshioka Kyushu University, Fukuoka, Japan
	Funding: Supported by the Quantum Beam Fundamentals Development Program MEXT, a Grant-in-Aid for Creative Scientific Research of MEXT Program No.19GS0210 and No.23244047, Yamada Science Foundation, and KEK. An accelerator/decelerator for slow neutron beams has been demonstrated. The energy of a neutron can be increased or decreased by flipping the neutron spin (directly coupled to magnetic dipole moment) in magnetic field. This device is a combination of a gradient magnetic field and an RF magnetic field. Because the RF frequency for the spin flip is a function of the external magnetic field, only neutrons that are located in a specific magnetic field level will be spin-flipped at a given RF frequency. By changing the RF frequency, the energy change can be selected in the gradient magnetic field. The maximum field of the gradient magnet is 1 T, which corresponds to the energy change of 120 neV. The magnetic field linearly decreases to 0.2T within 25 cm. By putting this device on a beamline from a pulsed neutron source, neutron rebuncher is realized. The dense slow neutrons are important to suppress the systematic errors for the measurement of neutron electric dipole moment (nEDM). The combination of spallation neutron source and this neutron rebuncher is suitable to the measurement of nEDM. A review of current status of our plan for nEDM experiment at J-PARC will be also presented.
	Slides MO3A04 [3.750 MB]

MOPLB04	A 10 MeV L-band Linac for Irradiation Applications in China	linac, electron, gun, klystron	147
	G. Pei, Y.L. Chi, M.H. Dai, D.Y. He, X. He, X. Li, J. Liu, C. Ma, X. Wang, C.H. Yu, F. Zhao, J. Zhao, Z.S. Zhou IHEP, Beijing, People's Republic of China Y. Feng, H. Huang, S. Shi, E. Tang, X. Yang, Q. Yuan, Z. Zhu Institute of High Energy Physics (IHEP), People's Republic of China Z. Li, X. Zhang Wuxi EL PONT Radiation Technology Ltd, Wuxi, People's Republic of China
	The electron linear accelerator has wide applications, and the demands are keeping growing for the irradiation applications in China. A high beam power 10 MeV L-band Linac has been developed recently as a joint venture of Institute of High Energy Physics and EL-PONT Company. The Thales TH2104U klystron, 3 A thermionic electron gun and three meter L-band disk-loaded constant impedance RF structure are adopted. A stable electron beam of 10 MeV, 40 kW has been obtained in the last May with a microwave to beam efficiency of about 65%. In this paper we will present the detailed design issues and beam commissioning.
	Slides MOPLB04 [1.800 MB]

MOPLB12	X-Ray Local Energy Spectrum Measurement on Tsinghua Thomson Scattering X-Ray Source (TTX)	scattering, electron, laser, photon	171
	Y.-C. Du, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, H. Zha, Z. Zhang TUB, Beijing, People's Republic of China
	Thomson scattering X-ray source, in which the TW laser pulse is scattered by the relativistic electron beam, can provide ultra short, monochromatic, high flux, tunable polarized hard X-ray pulse which is can widely used in physical, chemical and biological process research, ultra-fast phase contrast imaging, and so on. Since the pulse duration of X-ray is as short as picosecond and the flux in one pulse is high, it is difficult to measure the x-ray spectrum. In this paper, we present the X-ray spectrum measurement experiment on Tsinghua Thomson scattering. The preliminary experimental results shows the maximum X-ray energy is about 47 keV, which is agree well with the simulations.
	Slides MOPLB12 [1.311 MB]

MOPB007	Study of Microbunching Instabilitity in the Linac of the Shanghai Soft X-Ray Free Electron Laser Facility	linac, impedance, FEL, electron	189
	D. Huang, Q. Gu, M. Zhang SINAP, Shanghai, People's Republic of China
	The microbunching instability in the LINAC of a FEL facility has always been an issue which may degrade the quality of the electron beam. As the result, the whole facility may not be working properly. Shanghai soft X-ray FEL project (SXFEL), which is planned to start construction by the end of 2012, will be the first X-ray FEL facility in China. In this article, detailed study will be given based on the physical design of the facility to gain better understanding and control over the possible microbunching instability in SXFEL, which is critical to the success of the project. Moreover, the contribution of the possible plasma effects to the instability will also be studied by modifying the physical model of the longitudinal space charge (LSC) impedance.

MOPB022	RF Characteristic Studies on the Whole Accelerating Structure for the BEPCII Linear Accelerator	linac, vacuum, impedance, electromagnetic-fields	219
	S. Pei, M. Hou, X. Li, J.R. Zhang IHEP, Beijing, People's Republic of China B.L. Wang SINAP, Shanghai, People's Republic of China
	An accelerating structure is one device to boost the particle energy. 2856 MHz 3 m long travelling wave disk-loaded accelerating structure is applied in BEPCII linac, its RF characteristics are mainly determined by the 84 regular cells located between the input and output couplers. Input and output couplers need to be included when the whole structure RF characteristics are simulated before fabrication; otherwise it would be difficult to obtain the travelling wave fields excited in the whole structure. If the real 3D couplers are modelled during the design process, a large amount of computer resources and time need to be used. However, if the redesigned azimuth symmetric coupler is used to replace the real 3D one during the simulation process, much less computer resources and time are required. With this method proposed here, the simulation results agree well with the theoretically calculated and experimentally measured ones. *peisl@ihep.ac.cn

MOPB036	Feasibility Study of Short Pulse Mode Operation for Multi-turn ERL Light Source	linac, emittance, undulator, acceleration	255
	T. Atkinson, A.V. Bondarenko, A.N. Matveenko, Y. Petenev HZB, Berlin, Germany
	The optics and simulation group at HZB are designing Germany’s future light source. Based on the emerging Energy Recovery Linac super conducting technology, the Femto-Science-Factory (FSF) will provide its users with ultra-bright photons of Angstrom wavelength at 6 GeV. The FSF is intended to be a multi-user facility and offer a wide variety of operation modes. A low emittance ~0.1 μm rad mode will operate in conjunction with a short-pulse ~10 fs mode. This paper highlights the physical limitations when trying to offer interchangeable modes and preserve beam high quality.

MOPB042	On-line Dispersion Free Steering for the Main Linac of CLIC	emittance, ground-motion, feedback, linac	267
	J. Pfingstner, D. Schulte CERN, Geneva, Switzerland
	For future linear colliders as well as for light sources, ground motion effects are a severe problem for the accelerator performance. After a few minutes, orbit feedback systems are not sufficient to mitigate all ground motion effects and additional long term methods will have to be deployed. In this paper, the long term ground motion effects in the main linac of the Compact Linear Collider (CLIC) are analysed via simulation studies. The primary growth of the projected emittance is identified to originate from chromatic dilutions due to dispersive beam orbits. To counter this effect, an on-line identification algorithm is applied to measure the dispersion parasitically. This dispersion estimate is used to correct the beam orbit with an iterative dispersion free steering algorithm. The presented results are not only of interest for the CLIC project, but for all linacs in which the dispersive orbit has to be corrected over time.

MOPB046	A 10 MeV L-band Linac for Irradiation Applications in China	linac, electron, gun, klystron	276
	G. Pei, Y.L. Chi, M.H. Dai, D.Y. He, X. He, X. Li, J. Liu, C. Ma, X. Wang, X.W. Yang, C.H. Yu, F. Zhao, J. Zhao, Z.S. Zhou IHEP, Beijing, People's Republic of China Y. Feng, H. Huang, S. Shi, E. Tang, X. Yang, Q. Yuan, Z. Zhu Institute of High Energy Physics (IHEP), People's Republic of China Z. Li, X. Zhang Wuxi EL PONT Radiation Technology Ltd, Wuxi, People's Republic of China
	The electron linear accelerator has wide applications, and the demands are keeping growing for the irradiation applications in China. A high beam power 10 MeV L-band Linac has been developed recently as a joint venture of Institute of High Energy Physics and EL-PONT Company. The Thales TH2104U klystron, 3 A thermionic electron gun and three meter L-band disk-loaded constant impedance RF structure are adopted. A stable electron beam of 10 MeV, 40 kW has been obtained in the last May with a microwave to beam efficiency of about 65%. In this paper we will present the detailed design issues and beam commissioning.

MOPB056	Multipacting Analysis of High-Velocity Superconducting Spoke Resonators	electron, cavity, site, superconductivity	303
	C.S. Hopper, J.R. Delayen ODU, Norfolk, Virginia, USA
	Some of the advantages of superconducting spoke cavities are currently being investigated for the high-velocity regime. When determining a final, optimized geometry, one must consider the possible limiting effects multipacting could have on the cavity. We report on the results of analytical calculations and numerical simulations of multipacting electrons in superconducting spoke cavities and methods for reducing their impact.

MOPB057	Mechanical Study of the First Superconducting Half-wave Resonator for Injector II of CADS Project	cavity, HOM, controls, cryomodule	306
	S. He, Y. He, S.C. Huang, F.F. Wang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	Funding: This work is Supported by the National Natural Science Foundation of China (Grant Agreement 91026001) Within the framework of the China Accelerator-Driven Sub-critical Systems (CADS) project, Institute of Modern Physics (IMP) Chinese Academic of Sciences has proposed a 162.5 MHz Half-Wave Resonator (HWR) Superconducting cavity for low energy section (β=0.09) of high power proton linear accelerators as a new injector II for CIADS. For the geometrical design of superconducting cavities structure mechanical simulations are essential to predict mechanical eigenmodes and the deformation of the cavity walls due to bath pressure effects and the cavity cool-down. Additionally, the tuning analysis has been investigated to control the frequency against microphonics and Lorentz force detuning. Therefore, several RF, static structure, thermal and modal analysis with a three-dimensional Finite-Element Method (FEM) code Traditional ANSYS have been performed.

MOPB059	The Superconducting CH Cavity Development in IMP*	cavity, linac, niobium, resonance	309
	M.X. Xu, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, Z.J. Wang, J.W. Xia, Y.Z. Yang, W.M. Yue, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	Funding: Work supported by 91026001 Nature Science Foundation of China The Cross-Bar H-type (CH) cavity is a multi-gap drift tube structure operated in the H21 mode [1]. The Institute of Modern Physics (IMP) has been doing research and development on this type of superconducting CH cavity which can work at the C-ADS (accelerator driver sub-critical system of China). A new geometry CH cavity has been proposed which have smaller radius. It’s suitable in fabrication, and it’s can reduce cost too .Detailed numerical simulations with CST MicroWave Studio have been performed. An overall surface reduction of 30% against the old structure seems feasible. A copper model CH cavity is being fabrication for validating the simulations and the procedure of fabricating niobium cavity.

MOPB072	Multipole Expansion of the Fields in Superconducting High-Velocity Spoke Cavities	cavity, multipole, quadrupole, linac	345
	R.G. Olave, J.R. Delayen, C.S. Hopper ODU, Norfolk, Virginia, USA
	Multi-spokes superconducting cavities in the high-beta regime are being considered for a number of applications. In order to accurately model the dynamics of the particles in such cavities, knowledge of the fields off-axis are needed. We present a study of the multipoles expansion of the fields from an EM simulation field data for a two-spoke cavity operating at 325 MHz, β = 0.82 and 500 MHz, β = 1.

MOPB074	Thermo-Mechanical Simulations of the Frequency Tuning Plunger for the IFMIF Half-Wave Resonator	niobium, cavity, vacuum, cryomodule	351
	N. Bazin, P. Bosland, S. Chel, G. Devanz, N. Grouas, P. Hardy, J. Migne, F. Orsini, F. Peauger CEA/DSM/IRFU, France
	In the framework of the International Fusion Materials Irradiation Facility (IFMIF), a superconducting option has been chosen for the 5 MeV RF Linac of the first phase of the project (EVEDA), based on a cryomodule composed of 8 HWRs, 8 RF couplers and 8 Solenoid packages. The frequency tuning system of the IFMIF HWR is an innovated system based on a capacitive plunger installed in the electric field region allowing a large tuning range. Following the cold test results obtained on HWR equipped with the first design of plunger in 2011, it was decided to develop a new design of a fully-niobium plunger. The paper will present the development of the new plunger concepts and the thermo-mechanical simulations. For the mechanical simulations, the aim is to sufficiently deform the plunger to tune the cavity while staying in the elastic range of the niobium material. For the thermal simulations, all the non-linear properties of the materials and the effects of the RF fields are taken into account: thermal conductivity and surface resistance are depending on the temperature, RF fields computed with dedicated software are leading to thermal dissipations in the materials and the vacuum seal. F. Orsini et al., “Vertical tests preliminary results of the IFMIF cavity prototypes and cryomodule development”, SRF 2011, Chigaco, USA

MOPB089	X-Ray Local Energy Spectrum Measurement at Tsinghua Thomson Scattering X-Ray Source (TTX)	scattering, electron, laser, photon	383
	Y.-C. Du, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, H. Zha, Z. Zhang TUB, Beijing, People's Republic of China
	Thomson scattering X-ray source, in which the TW laser pulse is scattered by the relativistic electron beam, can provide ultra short, monochromatic, high flux, tunable polarized hard X-ray pulse which is can widely used in physical, chemical and biological process research, ultra-fast phase contrast imaging, and so on. Since the pulse duration of X-ray is as short as picosecond and the flux in one pulse is high, it is difficult to measure the x-ray spectrum. In this paper, we present the X-ray spectrum measurement experiment on Tsinghua Thomson scattering. The preliminary experimental results shows the maximum X-ray energy is about 47 keV, which is agree well with the simulations.

MOPB094	Simulation Study on the Longitudinal Bunch Shape Measurement by RF Chopper at J-PARC Linac	cavity, emittance, linac, DTL	395
	T. Maruta JAEA/J-PARC, Tokai-mura, Japan M. Ikegami J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	A RF chopper is placed in the medium energy transport section (MEBT1) at J-PARC linac. The chopper is normally driven at synchronous phase of 0 degree to give a maximum deflection. The chopper has two RF gaps and both of them deflect a beam bunch horizontally while RF is on. In the MEBT1 section, while we have a transverse emittance monitor, there is no longitudinal monitor. It is hard to newly place a longitudinal beam monitor there due to space limitation. We conduct a simulation which studies on the usability of the chopper to a longitudinal beam monitor. When the synchronous phase of the chopper is ± 90 degree, the longitudinal beam profile is projected to horizontal beam distribution. In this presentation, we introduce simulation results.

MOPB098	Planning for Experimental Demonstration of Transverse Emittance Transfer at the GSI UNILAC through Eigen-Emittance Shaping	emittance, quadrupole, coupling, scattering	404
	C. Xiao, O.K. Kester IAP, Frankfurt am Main, Germany L. Groening GSI, Darmstadt, Germany
	The minimum transverse emittances achievable in a beam line are determined by the two transverse eigen-emittances of the beam. For vanishing interplane correlations they are equal to the transverse rms-emittances. Eigen-emittances are constants of motion for all symplectic beam line elements, i.e. (even tilted) linear elements. To allow for rms-emittance transfer, the eigen-emittances are changed by a non-symplectic action to the beam, preferably preserving the 4d-rms-emittance. Unlike emittance swapping the presented concept will allow transforming a beam of equal rms-emittances into a beam of different rms-emittances while preserving the 4d-rms-emittance. This contribution will introduce the concept for eigen-emittance shaping and rms-emittance transfer at an ion linac. The actual work status towards the experimental demonstration of the concept at the GSI UNILAC is presented.

TUPLB05	Computational Model Analysis for Experimental Observation of Optical Current Noise Suppression below the Shot-Noise Limit	plasma, electron, linac, beam-transport	451
	A. Gover University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel A. Nause University of Tel Aviv, Tel Aviv, Israel
	Funding: We acknowledge support of the Israel Science Foundation grant We report first demonstration of optical frequency current shot-noise suppression in a relativistic e-beam. This process is made possible by collective Coulomb interaction between the electrons of a cold intense beam during beam drift, and is essentially a process of longitudinal beam-plasma oscillation [1]. Suppression of beam current noise below the classical “shot-noise” level has been known in the microwave tubes art [2]. This is the first time that it is demonstrated in the optical regime. We predict that the scheme can be extended to the XUV and possibly to shorter wavelengths with further development of technology. The fundamental current shot-noise determines the level of incoherent spontaneous radiation emission from electron-beam optical radiation sources and SASE-FELs [3]. Suppressing shot-noise would make it possible to attain spontaneous emission sub-radiance [4] and surpass the classical coherence limits of seed-injected FELs. The effect was demonstrated by measuring sub-linear growth as a function of current of the OTR Radiation. This finding indicates that the beam charge homogenizes due to the collective interaction, and its distribution becomes sub-Poissonian. [1] A. Gover, E. Dyunin, PRL, 102, 154801, 2009 [2] H. Haus, N. Robinson, Proc. IRE, 43, 981 (1955) [3] P. Emma, et al , Nature Photonics 4, 641 (2010) [4] A. Dicke, Phys. Rev. 93, 99 (1954)

TUPLB12	Development of Permanent Magnet Focusing System for Klystrons	klystron, focusing, permanent-magnet, cathode	470
	Y. Fuwa, Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan S. Fukuda, S. Michizono KEK, Ibaraki, Japan
	The Distributed RF System (DRFS) for the International Linear Collider (ILC) requires thousands of klystrons. The failure rate of the power supply for solenoid focusing coil of each klystron may be a critical issue for a regular operation of the ILC. A permanent magnet beam focusing system can increase reliability and eliminate their power consumption. Since the required magnetic field is not high in this system, inexpensive anisotropic ferrite magnets can be used instead of magnets containing rare earth materials. In order to prove its feasibility, a test model of a permanent magnet focusing beam system is constructed and a power test of the klystron for DRFS with this model is under preparation. The results of magnetic field distribution measurement and the power test will be presented.
	Slides TUPLB12 [1.357 MB]

TUPB001	The Fine Structure of the Zone of Particle Interaction with a Finite Length Periodic Structure	wakefield, impedance, diagnostics, emittance	473
	V.V. Paramonov RAS/INR, Moscow, Russia
	The periodic constant impedance deflecting structures are widely used for a special beam diagnostic in FEL facilities. The method, based on frequency domain approach, was developed to estimate long range wake fields structure parameters in a wide frequency range. It is shown, that regardless to number of cells in the structure, at each passband to the zone of particle effective interaction with the structure belongs several, at least three modes. The usual time domain simulations provide the total estimation for loss factor or kick factor values and modes separation in the time domain approach requires enormous simulations.

TUPB005	Computational Model Analysis for Experimental Observation of Optical Current Noise Suppression Below the Shot-noise Limit	plasma, electron, linac, beam-transport	482
	A. Gover University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel A. Nause University of Tel Aviv, Tel Aviv, Israel
	Funding: We acknowledge support of the Israel Science Foundation grant We report first demonstration of optical frequency current shot-noise suppression in a relativistic e-beam. This process is made possible by collective Coulomb interaction between the electrons of a cold intense beam during beam drift, and is essentially a process of longitudinal beam-plasma oscillation.[1] Suppression of beam current noise below the classical “shot-noise” level has been known in the microwave tubes art [2]. This is the first time that it is demonstrated in the optical regime. We predict that the scheme can be extended to the XUV and possibly to shorter wavelengths with further development of technology. The fundamental current shot-noise determines the level of incoherent spontaneous radiation emission from electron-beam optical radiation sources and SASE-FELs [3]. Suppressing shot-noise would make it possible to attain spontaneous emission sub-radiance [4] and surpass the classical coherence limits of seed-injected FELs. The effect was demonstrated by measuring sub-linear growth as a function of current of the OTR Radiation. This finding indicates that the beam charge homogenizes due to the collective interaction, and its distribution becomes sub-Poissonian. [1] A. Gover, E. Dyunin, PRL, 102, 154801, 2009 [2] H. Haus, N. Robinson, Proc. IRE, 43, 981 (1955) [3] P. Emma, et al , Nature Photonics 4, 641 (2010) [4] A. Dicke, Phys. Rev. 93, 99 (1954)

TUPB018	Study of Beam-Based Alignment for Shanghai Soft X-Ray FEL Facility	linac, emittance, alignment, FEL	513
	D. Gu, Q. Gu, D. Huang, M. Zhang, M.H. Zhao SINAP, Shanghai, People's Republic of China
	In linear accelerators, dispersion caused by quadrupole misalignment and transverse wake-field effect caused by alignment errors of accelerate structures will lead to a significant emittance growth. There are more stringent restrictions on SXFEL, the traditional optical alignment can no longer meet its requirements, but the Beam-Based Alignment(BBA) method allows more precise alignment, further reduce the Linac errors to meet SXFEL requirements .In undulator sections, orbit changes are not only caused by misalignments of quadrupole magnet position ,but also the errors of undulator magnetic. In order to achieve alignment accuracy over longer distance, we measuring BPM data under different conditions and using SVD algorithm for calculation and analysis, we can get the quadrupole magnet errors and BPM offset. With the method above, software based on MATLAB has been designed and compared the results with other software.

TUPB023	The Optimization of RF Deflector Input Power Coupler	coupling, emittance, electron, diagnostics	528
	A.Yu. Smirnov, O.A. Adonev, P.V. Binyukov, N.P. Sobenin MEPhI, Moscow, Russia
	This paper concerns the investigation of different types of input power cell for S-band RF electron deflector. This device serving for slice emittance diagnostics is a disc-loaded waveguide which operates with TE11-like wave in traveling wave regime with 120 deg phase shift per cell. Since this deflector meets the restriction on its length and has to provide high enough deflecting potential to a particle during its flight time it is significant to increase the transversal field strength in coupling cell or to shorten it so that the deflecting potential remains constant. The total structure consists of 14 regular cells and two couplers. As it is now all cells have the same length equal to D=33.34 mm and the field in couplers is lower than that of regular cells. In this paper different length are considered and numerically simulated in order to choose the best one.

TUPB031	Beam Envelope Analysis and Simulation	linac, ion, emittance, controls	543
	V.S. Dyubkov, A.S. Plastun MEPhI, Moscow, Russia
	Forming the charge particle beams with small cross-sections and low energies is an actual problem for a linac design. That beams are used actively for isotope therapy, ion implantation, etc. Beam emittance is its quality factor, and it should be matched with a facility channel acceptance. The method for beam dynamics analysis at linac is developed in terms of non-coherent particle oscillation study. Nonlinear beam dynamics is investigated by using this method. It is shown that this technique allows one to realize effective beam emittance control. Analytical results obtained are verified by means of numerical simulation.

TUPB035	A New Design of the RFQ Channel for GSI HITRAP Facility	rfq, ion, DTL, linac	555
	S.G. Yaramyshev, W.A. Barth, G. Clemente, L.A. Dahl, V. Gettmann, F. Herfurth, M. Kaiser, M.T. Maier, D. Neidherr, A. Orzhekhovskaya, H. Vormann, G. Vorobjev GSI, Darmstadt, Germany R. Repnow MPI-K, Heidelberg, Germany
	The HITRAP linac at GSI is designed to decelerate ions with mass to charge ratio of A/Z<3 from 4 MeV/u to 6 keV/u for experiments with ion traps. The particles are decelerated to 500 keV/u with an IH-DTL stucture and finally to 6 keV/u with a 4-rod RFQ. During commissioning stage the deceleration to approx. 500 keV/u was successfully demonstrated, while no particles behind the RFQ with an energy of 6 keV/u were observed. Dedicated simulations with DYNAMION code, based on 3D-fotometrie of the fabricated RFQ electrodes were successfully performed comprehending the commissioning results. In a second step the simulations have been experimentally confirmed at a test-stand (MPI, Heidelberg). An input energy, accepted by the RFQ channel is significantly higher than design value. For this reason the longitudinal beam emittance after deceleration with IH structure does not fit to the longitudinal RFQ acceptance. To solve this problem a new design of the RFQ channel with a correct input energy has been started. New RFQ parameters and the results of the beam dynamics simulations are presented in this paper.

TUPB036	Design of Re-Buncher Cavity for Heavy-ion LINAC in IMP	cavity, DTL, linac, impedance	558
	L.P. Sun, X. Du, Y. He, A. Shi, C. Zhang, Z.L. Zhang IMP, Lanzhou, People's Republic of China
	A re-buncher with spiral arms for a heavy ion linear accelerator named as SSC-LNAC at HIRFL (the heavy ion research facility of Lanzhou) has been constructed. The re-buncher, which is used for beam longitudinal modulation and match between the RFQ and DTL, is designed to be operated in continuous wave (CW) mode at the Medium-Energy Beam-Transport (MEBT) line to maintain the beam intensity and quality. Because of the longitudinal space limitation, the re-buncher has to be very compact and will be built with four gaps. We determined the key parameters of the re-buncher cavity from the simulations using Microwave Studio software, such as the resonant frequency, the quality factor Q and the shunt impedance. The detailed design of a 53.667 MHz spiral cavity and measurement results of its prototype will be presented.

TUPB041	Scattering of H⁻ Stripped Electrons from SEM Grids and Wire Scanners at the CERN LINAC4	electron, scattering, linac, polarization	567
	F. Roncarolo, E. Chevallay, M. Duraffourg, G.J. Focker, C. Heßler, U. Raich, VC. Vuitton, F. Zocca CERN, Geneva, Switzerland B. Cheymol ESS, Lund, Sweden
	At the CERN LINAC4, wire grids and scanners will be used to characterize the H⁻ beam transverse profile at different stages along the acceleration to 160 MeV. The wire signal will be determined by the balance between secondary emission and number of charges stopped in the wire, which will depend on the wire material and diameter, the possible choice of biasing (DC) the wires and the beam energy. The outermost electrons of H⁻ ions impinging on a wire are stripped in the first nanometers of material. A portion of such electrons are scattered away from the wire and can reach the neighboring wires. In addition, scattered electrons hitting the surrounding beam pipe generate secondary electrons that can also perturb the measurement. Monte Carlo simulations, analytical calculations and a laboratory experiment allowed quantifying the amount of scattering and the scattered particles distributions. The experiment was based on 70 keV electrons, well reproducing the case of 128 MeV H⁻ ions. For all the LINAC4 simulated cases the predicted effect on the beam size reconstruction results in a relative error of less than 5%.

TUPB048	Discussion of the Optimisation of a Linac Lattice to Minimise Disruption by a Class of Parasitic Modes	cavity, coupling, linac, lattice	585
	S. Molloy ESS, Lund, Sweden R. Ainsworth Royal Holloway, University of London, Surrey, United Kingdom
	It is well known that each resonant mode in the RF spectrum of multi-cell accelerating cavities will split into a passband containing a number of modes, and that the coupling of these modes to the beam is dependent on the velocity of the accelerated particles. If these modes are found to degrade the quality of the beam, it is possible to take various measures to damp them, and thus keep their effect below some critical threshold. In the case of the parasitic modes within the same passband as the fundamental accelerating mode, their frequency is typically too close to that of the fundamental to allow their power to be safely extracted, and so cavity designers must rely on the natural damping of the cavity itself. This note contains a theoretical discussion of the coupling of the beam to these passband modes for a large class of accelerating cavities, and provides a mathematical model for use during the design and optimisation of linacs.

TUPB052	Studies of Parasitic Cavity Modes for Proposed ESS Linac Lattices	linac, cavity, proton, lattice	591
	R. Ainsworth Royal Holloway, University of London, Surrey, United Kingdom S. Molloy ESS, Lund, Sweden
	The European Spallation Source (ESS) planned for construction in Lund, Sweden, will be the worlds most intense source of pulsed neutrons. The neutrons will be generated by the collision of a 2.5 GeV proton beam with a heavy-metal target. The superconducting section of the proton linac is split into three different types of cavities, and a question for the lattice designers is at which points in the beamline these splits should occur. This note studies various proposed designs for the ESS lattice from the point of view of the effect on the beam dynamics of the parasitic cavity modes lying close in frequency to the fundamental accelerating mode. Each linac design is characterised by the initial kinetic energy of the beam, as well as by the velocity of the beam at each of the points at which the cavity style changes. The scale of the phase-space disruption of the proton pulse is discussed, and some general conclusions for lattice designers are stated.

TUPB055	R&D of IMP Superconducting HWR for China ADS	cavity, niobium, linac, proton	600
	W.M. Yue, X.L. Guo, S. He, Y. He, R.X. Wang, P.R. Xiong, M.X. Xu, B. Zhang, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	The R&D program of IMP superconducting HWR is based on the China ADS, The aim is to build and test a HWR prototype on December 2012. We have designed a 162.5 MHz β=0.09 half-wave resonator (HWR), and a copper HWR has been fabricated in January 2012. The fabrication of a Nb HWR will be completed by September 2012, and the fabrication of a slow tuner and a high power coupler for this HWR will be completed then. In this poster, we present the HWR electromagnetic design, mechanical design, fabrication arts, copper HWR RF test result, the design of the slow tuner and the power coupler.

TUPB056	The Multipacting Simulation for the New-shaped QWR using TRACK3P	cavity, accelerating-gradient, electron, niobium	603
	C. Zhang, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, S.H. Zhang, S.X. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	In order to improve the electro-magnetic performance of the quarter wave resonator, a new-shaped cavity with an elliptical cylinder outer conductor has been proposed. This novel cavity design can provide much lower peak surface magnetic field and much higher Ra/Q0 and G. The Multipacting simulation has been done for this new QWR cavity using ACE3P/TRACK3P code, in this paper the simulation results will be presented and analyzed.

TUPB057	Structural Analysis of the New-Shaped QWR for HIAF in IMP	cavity, superconducting-cavity, SRF, controls	606
	C. Zhang, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, S.H. Zhang, S.X. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	Since the QWR cavity is very successful for the operation with frequency of 48 to 160 MHz and \beta value of 0.001 to 0.2, a new-shaped QWR is being designed for the low energy superconducting section of HIAF in the Institute of Modern Physics. The cavity will work at 81.25 MHz and \beta of 0.085，with a elliptical cylinder outer conductor to better its electro-magnetic performance and keep limited accelerating space. Structural design is an important aspect of the overall cavity implementation, and in order to minimize the frequency shift of the cavity due to the helium bath pressure fluctuations, the Lorentz force and microphonic excitation, stiffening elements have to be applied. In this paper, structural analyses of the new-shaped QWR are presented and stiffening methods are explored.

TUPB058	An Analytical Cavity Model for Fast Linac-Beam Tuning	multipole, quadrupole, cavity, dipole	609
	Z.Q. He, Z. Zheng TUB, Beijing, People's Republic of China Z.Q. He, Z. Liu, J. Wei, Y. Zhang FRIB, East Lansing, Michigan, USA
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 Non-axisymmetric RF cavities can produce axially asymmetric acceleration fields. Conventional method using numerical 3-D field tracking to address this feature is time-consuming and thus not appropriate for on-line beam tuning applications. In this paper, we develop analytical treatment of non-axisymmetric RF cavities. Multipole models of cavities are derived using realistic 3-D field in both longitudinal and transverse dimensions. Then, beam dynamics formulism is established. Finally, special case of FRIB quarter-wave resonators are calculated by the model and benchmarked against 3-D field tracking to ensure the efficiency and accuracy of the model.

TUPB060	Multipacting Suppression Modeling for Half Wave Resonator and RF Coupler*	cavity, electron, cryomodule, impedance	612
	Z. Zheng, A. Facco, Z. Liu, J. Popielarski, K. Saito, J. Wei, Y. Xu, Y. Zhang FRIB, East Lansing, Michigan, USA Z. Zheng TUB, Beijing, People's Republic of China
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 In prototype cryomodule test of Facility of Rare Isotope Beam (FRIB) β=0.53 half-wave-resonators (HWRs) severe multipacting barriers, prevented RF measurement at the full field specified. The multipacting could not be removed by several hours of RF conditioning. To better understand and to eliminate multipacting, physics models and CST simulations have been developed for both cavity and RF coupler. The simulations have good agreement with the multipacting discovered in coupler and cavity testing. Proposed cavity and coupler geometric optimizations are discussed in this paper.

TUPB061	ADRC Control for Beam Loading and Microphonics	controls, cavity, beam-loading, LLRF	615
	Z. Zheng, Z. Liu, J. Wei, Y. Zhang, S. Zhao FRIB, East Lansing, Michigan, USA Z. Zheng TUB, Beijing, People's Republic of China
	Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 Superconducting RF (SRF) cavities are subject to many disturbances such as beam loading and microphonics. Although we implemented Proportional Integral (PI) control and Active Disturbance Rejection Control (ADRC) in the Low Level RF (LLRF) system at FRIB to stabilize the RF field, the control loop gains are inadequate in the presence of beam loading and microphonics. An improved scheme is proposed and simulated with much higher gains are achieved. The feasibility to include piezo tuner in ADRC and PI circuit is also presented in this paper.

TUPB067	Development of a Superconducting Half-Wave Resonator for PXIE	cavity, linac, cryomodule, niobium	624
	Z.A. Conway, R.L. Fischer, S.M. Gerbick, M. Kedzie, M.P. Kelly, S.V. Kutsaev, B. Mustapha, P.N. Ostroumov, K.W. Shepard ANL, Argonne, USA I.V. Gonin, A. Lunin, V.P. Yakovlev Fermilab, Batavia, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics and Nuclear Physics, under contract DE-AC02-76CH03000 and DE-AC02-06CH11357 An ambitious upgrade to the FNAL accelerator complex is progressing in the Project-X Injector Experiment (PXIE). The PXIE accelerator requires 8 superconducting half-wave resonators optimized for the acceleration of 1 mA β = 0.11 H⁻ ion beams. Here we present the status of the half-wave resonator development, focusing particularly on cavity design, with a brief update on prototype fabrication.

TUPB069	BEAMDULAC-SCL Code for Complex Approach of Beam Dynamic Investigation in SC LINAC	ion, linac, focusing, solenoid	630
	A.V. Samoshin MEPhI, Moscow, Russia
	Periodic sequences of independently phased accelerating cavities and focusing solenoids are used in MeV and GeV energy range linacs. The beam dynamic investigation is difficult for such superconducting linear accelerator. The matrix calculation was preferably used for primary choused of accelerating structure parameters. This method does not allows properly investigate the longitudinal motion. The smooth approximation can be used to investigate the nonlinear ion beam dynamics in such accelerating structure and to calculate longitudinal and transverse acceptances. The potential function and the equation of motion in the Hamilton form are devised by the smooth approximation. The advantages and disadvantages of each method will describe, the results of investigation will compare. The user friendly software BEAMDULAC-SCL for ion beam dynamic analysis was created. A numerical simulation of beam dynamics in the real field are carried out for the different variants of the accelerator structure based on previously analytically obtained results.

TUPB071	First Measurements on the 325 MHz Superconducting CH Cavity	cavity, controls, linac, coupling	636
	M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany M. Amberg HIM, Mainz, Germany W.A. Barth, S. Mickat GSI, Darmstadt, Germany M. Pekeler RI Research Instruments GmbH, Bergisch Gladbach, Germany
	Funding: Work supported by GSI, BMBF Contr. No. 06FY7102, 06FY9089I At the Institute for Applied Physics (IAP), Frankfurt University, a superconducting 325 MHz CH-Cavity has been designed and built. This 7-cell cavity has a geometrical \beta of 0.16 corresponding to a beam energy of 11.4 AMeV. The design gradient is 5 MV/m. Novel features of this resonator are a compact design, low peak fields, easy surface processing and power coupling. Furthermore a new tuning system based on bellow tuners inside the resonator will control the frequency during operation. After successful rf tests in Frankfurt the cavity will be tested with a 10 mA, 11.4 AMeV beam delivered by the GSI UNILAC. In this paper first measurements and corresponding simulations will be presented.

TUPB072	Status of the Superconducting CW Demonstrator for GSI	cavity, linac, solenoid, cryogenics	639
	F.D. Dziuba, M. Amberg, M. Busch, H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany K. Aulenbacher IKP, Mainz, Germany W.A. Barth, S. Mickat GSI, Darmstadt, Germany
	Funding: Helmholtz Institut Mainz (HIM), GSI, BMBF Contr. No. 06FY7102 Since the existing UNILAC at GSI will be used as an injector for the FAIR facility a new superconducting (sc) continous wave (cw) LINAC is highly requested by a broad community of future users to fulfil the requirements of nuclear chemistry, especially in the research field of Super Heavy Elements (SHE). This LINAC is under design in collaboration with the Institute for Applied Physics (IAP) of Frankfurt University, GSI and the Helmholtz Institut Mainz (HIM). It will consist of 9 sc Crossbar-H-mode (CH) cavities operated at 217 MHz which provide an energy up to 7.3 AMeV. Currently, a prototype of the cw LINAC is under development. This demonstrator comprises the first sc CH cavity of the LINAC embedded between two sc solenoids mounted in a horizontal cryomodule. One important milestone of the project will be a full performance test of the demonstrator by injecting and accelerating a beam from the GSI High Charge State Injector (HLI) in 2014. The status of the demonstrator is presented.

TUPB073	Design and Simulation of a Test Model for a Tri-Spoke Cavity at RIKEN	cavity, vacuum, superconducting-cavity, electron	642
	L. Lu RIKEN, Saitama, Japan O. Kamigaito, N. Sakamoto, K. Suda, K. Yamada RIKEN Nishina Center, Wako, Japan
	A design for a tri-spoke-type superconducting cavity for uranium beams with β = 0.303 and a 219 MHz operational frequency is presented. And a test model designed and assembled by two end-wall flanges and one triparted part of the designed tri-spoke cavity, was expected to be built using the same fabrication technology that is supposed for Nb cavity manufacture. The designs and simulations of the tri-spoke cavity and the test model will be reported in this paper.

TUPB082	Beam Loss Track Measurements by a Fast Trigger Scheme in J-PARC Linac	linac, background, proton, neutron	663
	H. Sako, T. Maruta, A. Miura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	Funding: Work partially supported by Grant-in-Aid for Challenging Exploratory Research In J-PARC Linac, highest beam loss has been observed at the ACS (Annular-Coupled Structure linac) section. The primary source of the beam loss is considered to be H⁰ produced by an interaction of H⁻ beams with remnant gas. The H⁰ hits the beam duct, converted to H⁺, and escapes from the beam duct. To detect the H⁺'s and estimate the absolute magnitude of the beam loss, we constructed a detector system, which consists of 6 planes of hodoscopes made of 16 scintillation fibers with 64 x 64 mm² area. The scintillation light is measured by multi-anode photomultipliers. In the ACS section, two planes to measure horizontal positions are installed, and at about 1 m downstream positions, two planes for horizontal measurements and two for vertical measurements are placed. We will reconstruct charged particles passing through all the 6 planes, and measure the velocity by time-of-flight and energy loss to identify particle species. We present new measurements since the recovery of the J-PARC after the earthquake started in April 2012 by a new fast trigger scheme using dynode signals of photomultipliers in order to improve signal-to-noise ratios.

TUPB090	Development of Permanent Magnet Focusing System for Klystrons	klystron, focusing, permanent-magnet, cathode	669
	Y. Fuwa, Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan S. Fukuda, S. Michizono KEK, Ibaraki, Japan
	A permanent magnet focusing system for klystrons is under development to improve reliability of RF supply system and reduce power consumption. To save production cost, anisotropic ferrite magnets are used in this system. A test model has been fabricated and the power test of a 750 kW klystron with this focusing magnet is carried out. 60 % of the nominal output power has been achieved at a preliminary power test so far

TUPB091	176 MHz Solid State Microwave Generator Design	impedance, linac, scattering, resonance	672
	A.Yu. Smirnov, E.V. Ivanov, A.A. Krasnov, K.I. Nikolskiy, N.V. Tikhomirova Siemens Research Center, Moscow,, Russia O. Heid, T.J.S. Hughes Siemens AG, Erlangen, Germany
	This paper concerns the R&D work upon design of a compact RF amplifier to be used for superconducting CW cavities. The machine under development will operate at 176 MHz with output power of 25 kW in continuous wave regime. It consists of 50 push-pull PCB modules (approx. 500W output power each), connected in parallel to several radial filter rings, which both allow class-F operation and combine the power from the modules, delivering it to a single 50 Ω coax cable. The CST simulations ad the design of 324 MHz test prototype are presented.

TUPB093	Compact 4 kW Variable RF Power Coupler for FRIB Quarter-wave Cavities	cavity, cryomodule, vacuum, linac	678
	M.P. Kelly, Z.A. Conway, M. Kedzie, S.V. Kutsaev ANL, Argonne, USA J.L. Crisp, L.L. Harle FRIB, East Lansing, Michigan, USA
	A new compact 4 kW power coupler has been designed and prototyped at Argonne National Laboratory in collaboration with Michigan State University. The coupler is intended for use on the β=0.085 80.5 MHz superconducting quarter-wave cavities for the FRIB driver linac and also for the planned ReA6 quarter-wave cavity cryomodule. The design has a cold RF window and a 3 cm variable bellows section. The 16 cm overall length of the RF window and bellows facilitates a simple and compact installation onto the cavity inside the clean room. A prototype have been cold tested with high power under realistic conditions at Argonne and results are presented.

TUPB094	High Power Tests of TRASCO RFQ Couplers	vacuum, cavity, rfq, klystron	681
	E. Fagotti, L. Antoniazzi, F. Grespan, A. Palmieri, F. Scarpa INFN/LNL, Legnaro (PD), Italy O. Brunasso Cattarello, R. Panero INFN-Torino, Torino, Italy M. Desmons CEA/DSM/IRFU, France
	The 352.2 MHz 7.13 m long TRASCO RFQ requires an overall amount of 900 kW CW RF power in order to deliver the 40 mA proton beam from the initial energy of 80 keV to the final energy of 5 MeV. For such a purpose a system of eight compact (ϕext=38 mm, ϕint=19.4 mm) loop-based couplers was designed. In a first phase, only the first two (out of six) modules of the RFQ were tested at full power. Therefore only two (out of eight) couplers were used. In order to completely characterize these couplers, a dedicated test bench was prepared, consisting of a bridge waveguide and diagnostics (reflected power, vacuum, arc detectors etc.), onto which a couple of couplers was connected for transmission measurements. Each coupler was tested with a forward power of up to 140 kW. The description of the experimental setup and procedure, as well as the main results of the conditioning procedure will be reported in this paper.

TUPB097	The C-band RF Pulse Compression for Soft XFEL at SINAP	cavity, coupling, klystron, free-electron-laser	687
	C.P. Wang, Q. Gu, Z.T. Zhao SINAP, Shanghai, People's Republic of China
	A compact soft X-ray free electron laser facility is presently being constructed at shanghai institute of applied physics (SINAP), Chinese academy of science in 2012 and will be accomplished in 2014. This facility requires a compact linac with a high-gradient accelerating structure for a limited overall length less than 230 m. The c-band technology which is already used in KEK/Spring-8 linear accelerator is a good compromise for this compact facility and a c-and traveling-wave accelerating structure was already fabricated and tested at SINAP, so a c-band pulse compression will be required. AND a SLED type RF compression scheme is proposed for the C-band RF system of the soft XFEL and this scheme uses TE0.1.15 mode energy storage cavity for high Q-energy storage. The C-band pulse compression under development at SINAP has a high power gain about 3.1 and it is designed to compress the pulse width from 2.5 μs to 0.5 μs and multiply the input RF power of 50 MW to generate 160 MW peak RF power, and the coupling coefficient will be 8.5. It has three components: 3 dB coupler, mode convertors and the resonant cavities.

TUPB107	Amplitude and Phase Control of the Accelerating Field in the ESS Spoke Cavity	cavity, controls, feedback, beam-loading	708
	V.A. Goryashko, R.J.M.Y. Ruber, R.A. Yogi, V.G. Ziemann Uppsala University, Uppsala, Sweden
	We report about numerical simulations of the accelerating field dynamics in the ESS spoke cavity in the presence of the beam loading and Lorentz detuning. A slow feedforward is used to cure the Lorentz detuning whereas a fast feedback through a signal oscillator and cavity pre-detuning technique are applied to eliminate the beam loading effect. An analysis performed with a Simulink model shows that a combination of feedforward, feedback and cavity pre-detuning result in a substantially shorter stabilization time of the field voltage and phase on a required level as compared to a control method using only the feedforward and feedback. The latter allows one to obtain smaller magnitude but longer duration of deviations of the instantaneous voltage and phase from the required nominal values. As a result, a series of cavities only with feedforward and feedback needs an extra control technique to mitigate a cumulative systematic error rising in each cavity. In addition, a technique of adiabatic turning off of the RF power in order to prevent a high reflected power in the case of a sudden beam loss is studied.

TH2A004	Computational Model Analysis for Experimental Observation of Optical Current Noise Suppression Below the Shot-noise Limit	plasma, electron, linac, beam-transport	783
	A. Gover University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel A. Nause University of Tel Aviv, Tel Aviv, Israel
	Funding: We acknowledge support of the Israel Science Foundation grant We report first demonstration of optical frequency current shot-noise suppression in a relativistic e-beam. This process is made possible by collective Coulomb interaction between the electrons of a cold intense beam during beam drift, and is essentially a process of longitudinal beam-plasma oscillation.[1] Suppression of beam current noise below the classical “shot-noise” level has been known in the microwave tubes art [2]. This is the first time that it is demonstrated in the optical regime. We predict that the scheme can be extended to the XUV and possibly to shorter wavelengths with further development of technology. The fundamental current shot-noise determines the level of incoherent spontaneous radiation emission from electron-beam optical radiation sources and SASE-FELs [3]. Suppressing shot-noise would make it possible to attain spontaneous emission sub-radiance [4] and surpass the classical coherence limits of seed-injected FELs. The effect was demonstrated by measuring sub-linear growth as a function of current of the OTR Radiation. This finding indicates that the beam charge homogenizes due to the collective interaction, and its distribution becomes sub-Poissonian. [1] A. Gover, E. Dyunin, PRL, 102, 154801, 2009 [2] H. Haus, N. Robinson, Proc. IRE, 43, 981 (1955) [3] P. Emma, et al , Nature Photonics 4, 641 (2010) [4] A. Dicke, Phys. Rev. 93, 99 (1954)

THPLB03	Front-End Linac Design and Beam Dynamics Simulations for MYRRHA	rfq, DTL, emittance, linac	813
	C. Zhang, H. Klein, D. Mäder, H. Podlech, U. Ratzinger, A. Schempp, R. Tiede, M. Vossberg IAP, Frankfurt am Main, Germany
	Funding: Funded by the European Atomic Energy Community’s (Euratom) 7th Framework Programme under Grant Agreement n°269565. A 17MeV, 176MHz, and CW (Continuous Wave) proton linac is being developed as the front end of the driver accelerator for the MYRRHA facility in Mol, Belgium. Based on the promising preliminary design, further simulation and optimization studies have been performed with respect to code benchmarking, RFQ simulation using realistic LEBT output distributions, and an updated CH-DTL design with more detailed inter-tank configurations. This paper summarizes the new results.
	Slides THPLB03 [1.292 MB]

THPLB11	Experimental and Simulation Study of the Long-path-length Dynamics of a Space-charge-dominated Bunch	space-charge, electron, emittance, focusing	834
	I. Haber, B.L. Beaudoin, S. Bernal, R.A. Kishek, T.W. Koeth, Y. Mo UMD, College Park, Maryland, USA
	Funding: Work supported by the United States Department of Energy and the Office of Naval Research. The University of Maryland Electron Ring (UMER) is a low-energy (10 keV) electron facility built to study, on a scaled machine, the long-propagation-length evolution of a space-charge-dominated beam. Though constructed in a ring geometry to achieve a long path length at modest cost, UMER has observed important space-charge physics directly relevant to linear machines. Examples will be presented that emphasize studies of the longitudinal dynamics and comparisons to axisymmetric simulations. The detailed agreement obtained between simulation and experiment will be presented as evidence that the longitudinal physics observed is not strongly influenced by the ring geometry. Novel phenomena such as soliton formation, unimpeded bunch-end interpenetration, and an instability that occurs after this interpenetration, will be discussed.

THPB004	Current Status of the RAL Front End Test Stand (FETS) Project	rfq, ion, ion-source, diagnostics	846
	D.C. Plostinar, C. Gabor STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom S.M.H. Alsari, M. Aslaninejad, A. Kurup, J.K. Pozimski, P. Savage Imperial College of Science and Technology, Department of Physics, London, United Kingdom J.J. Back University of Warwick, Coventry, United Kingdom G.E. Boorman, A. Bosco Royal Holloway, University of London, Surrey, United Kingdom M.A. Clarke-Gayther, D.C. Faircloth, S.R. Lawrie, A.P. Letchford STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom S. Jolly UCL, London, United Kingdom
	The UK proton accelerator strategy aims to develop a viable high power proton driver with applications including spallation neutrons, the neutrino factory and ADSR. An essential first ingredient, identified as one of the main UK R&D accelerator projects, is the Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL), aimed at producing a high quality, high current, cleanly chopped H⁻ beam. Through its component parts, FETS has triggered development of a high brightness, 60 mA H⁻ ion source, a three-solenoid Low Energy Beam Transport line (LEBT), a 3 MeV four-vane Radio-Frequency Quadrupole (RFQ) and a Medium Energy Beam Transport line (MEBT) with a high speed chopper. The project is well advanced and when operational should be sufficiently versatile to explore a range of operating conditions. In this paper we present the current status of the construction, and plans for operation, experiments and future development.

THPB005	Front-End Linac Design and Beam Dynamics Simulations for MYRRHA	rfq, DTL, emittance, linac	849
	C. Zhang, H. Klein, D. Mäder, H. Podlech, U. Ratzinger, A. Schempp, R. Tiede, M. Vossberg IAP, Frankfurt am Main, Germany
	Funding: Funded by the European Atomic Energy Community’s (Euratom) 7th Framework Programme under Grant Agreement n°269565. A 17MeV, 176MHz, and CW (Continuous Wave) proton linac is being developed as the front end of the driver accelerator for the MYRRHA facility in Mol, Belgium. Based on the promising preliminary design, further simulation and optimization studies have been performed with respect to code benchmarking, RFQ simulation using realistic LEBT output distributions, and an updated CH-DTL design with more detailed inter-tank configurations. This paper summarizes the new results.

THPB007	A Pulsed Linac Front-end for ADS Applications	proton, rfq, emittance, linac	855
	U. Ratzinger, H. Podlech, A. Schempp, K. Volk IAP, Frankfurt am Main, Germany U. Hagen, O. Heid, T.J.S. Hughes Siemens AG, Erlangen, Germany H. Hoeltermann BEVATECH OHG, Offenbach/Main, Germany
	Quite a number of projects worldwide develop proton driver linacs for neutron sources and other accelerator driven systems. One trend is to use a high duty factor and superconducting cavities as much as possible. Alternatively, one can aim on short duty factor and count on a continuing rapid development of pulsed rf amplifiers based on power transistor technology. A 500 mA, 5 % duty factor layout of a proton injector is presented, consisting of a filament driven volume ion source, of a 150 keV transport section and of a 4 m long 162 MHz RFQ up to 2 MeV beam energy. Beam dynamics results as well as the technical design will be shown.

THPB008	A Coupled RFQ-IH Cavity for the Neutron Source FRANZ	rfq, cavity, DTL, coupling	858
	M. Heilmann, O. Meusel, D. Mäder, U. Ratzinger, A. Schempp, M. Schwarz IAP, Frankfurt am Main, Germany
	The Frankfurt neutron source FRANZ will deliver neutrons in the energy range from 1 to 500 keV with high pulsed intensities. A 2 MeV proton beam will produce protons via the 7Li(p,n)7Be reaction. The 175 MHz accelerator cavity consists of a 4-rod-RFQ coupled with an 8 gap interdigital H-type drift tube section, the total cavity length being 2.3m. The combined cavity will be powered by one RF amplifier to reduce investment and operation costs. The inductive power coupler will be at the RFQ part. The coupling into the IH - section is provided through a large aperture - mainly inductively. By CST - MWS - simulations as well as by an RF - model the voltage tuning along the cavity was investigated, and with special care the balance between both cavity sections. A first set of RFQ electrodes should allow to reach beam currents up to 50 mA in cw operation: The beam is pulsed with 100 ns, 250 kHz, while the cavity has to be operated cw due to the high rep. rate. The layout of the cavity cooling aims on a maximum accessible heat load of 200 kW.

THPB011	Linac4 45 keV Proton Beam Measurements	rfq, solenoid, linac, proton	867
	G. Bellodi, V.A. Dimov, L.M. Hein, J.-B. Lallement, A.M. Lombardi, O. Midttun, R. Scrivens CERN, Geneva, Switzerland P.A. Posocco Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	Linac4 is a 160 MeV normal-conducting H⁻ linear accelerator, which will replace the 50 MeV proton Linac (Linac2) as injector for the CERN proton complex. Commissioning of the low energy part - H⁻ source, a 45 keV Low Energy Beam Transport line (LEBT), a 3 MeV RFQ and a Medium Energy Beam Transport (MEBT) line - will start in fall 2012 on a dedicated test stand installation. In preparation to this, preliminary measurements were taken in the past few months using a 45 keV proton source and a temporary LEBT setup, with the aim of characterising the output beam by comparison with simulations. This also allowed a first verification of the diagnostics instrumentation and acquisition software tools. Measurements of beam profile, emittance and intensity were taken after the source, after the first and after the second LEBT solenoids respectively. Particle distributions were reconstructed from emittance scans and used as input to simulation studies of the beam transport through the line. Comparison of the results with the measurements allowed an experimental validation of the LEBT (in terms of misalignments and calibration points) and qualification of the beam at the source output.

THPB022	Beam Phase Measurement for PEFP Linear Accelerator	linac, DTL, LLRF, proton	894
	H.S. Kim, Y.-S. Cho, J.-H. Jang, H.-J. Kwon, J.Y. Ryu, K.T. Seol, Y.-G. Song KAERI, Daejon, Republic of Korea
	Funding: Works supported by the Ministry of Education, Science and Technology of Korean Government. According to the commissioning plan of the PEFP proton linac, an accurate measurement of beam phase is essential, especially for setting up the RF operating parameters of DTL. Beam position monitors (BPMs) installed between DTL tanks can provide information about the beam phase as well as about the beam transverse position. By using a BPM as a beam phase monitor, beam phase can be measured without additional devices on the linac or the beam line. The signals from 4 electrodes in the BPM can be summed by using a 4-way RF combiner, by which the effect of the transverse beam offset on the phase measurement can be eliminated. The combined BPM signal (350 MHz) is mixed with LO signal (300 MHz) and down-converted to IF signal (50 MHz), then fed into the signal processing unit, where the phase information is extracted by using IQ demodulation method with a sampling frequency of 40 MHz. In this paper, the beam phase measurement system and signal processing scheme will be presented.

THPB026	The Beam Commissioning Plan of Injector II in C-ADS	rfq, cavity, proton, diagnostics	906
	Z.J. Wang, Y. He, H. Jia, C. Li, S.H. Liu, W. Wu, X.B. Xu, B. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	The design work of the Injector II, which is 10 MeV proton linac, in C-ADS project is being finished and some key elements are being fabricated. Now it is necessary to definite the operation mode of beam commissioning, including the selection of the beam current, pulse length and repetition frequency. Also the beam commissions plan should be specified. The beam commissions procedures is simulated with t-mode code GPT. In this paper, the general beam commissioning plan of Injector II in CIADS and simulation results of commissions procedures are presented.

THPB030	DTL Design for ESS	DTL, linac, proton, drift-tube-linac	918
	M. Comunian, F. Grespan, A. Pisent INFN/LNL, Legnaro (PD), Italy R. De Prisco Lund University, Lund, Sweden M. Eshraqi ESS, Lund, Sweden P. Mereu INFN-Torino, Torino, Italy
	In the present design of the European Spallation Source (ESS) accelerator, the Drift Tube Linac (DTL) will accelerate a proton beam of 50 mA pulse peak current from 3 to 80 MeV. It is designed to operate at 352.2 MHz, with a duty cycle of 4% (3 ms pulse length, 14 Hz repetition period). Permanent magnet quadrupoles (PMQs) are used as focusing elements in a FODO lattice scheme, which leaves space for steerers and diagnostics . In this paper beam dynamics studies and preliminary RF design are shown, including constraints in terms of quadrupole dimensions, total length, field stability, RF power, peak electric field.

THPB046	RF Setup of the MedAustron RFQ	rfq, resonance, ion, pick-up	957
	B. Koubek, A. Schempp, J.S. Schmidt IAP, Frankfurt am Main, Germany J. Haeuser Kress GmbH, Biebergemuend, Germany
	A Radio Frequency Quadrupole (RFQ) was built for the injector of the cancer treatment facility MedAuston in Austria. For the RF design simulations were performed using CST Microwave Studio and the structure was manufactured by Firma Kress in Biebergemuend, Germany. The simulations and the RF setup of the delivered RFQ are presented in this paper.

THPB047	Test RFQ for the MAX Project	rfq, cavity, linac, proton	960
	M. Vossberg, H. Klein, H. Podlech, A. Schempp, C. Zhang IAP, Frankfurt am Main, Germany A. Bechtold NTG Neue Technologien GmbH & Co KG, Gelnhausen, Germany
	As a part of the MAX project it will be demonstrated by simulations and thermal measurements, that a 4-rod-RFQ is the right choice even at cw-operation. A 4-rod Test-RFQ with a resonance frequency of 175 MHz has been designed and built for the MAX-Project. But the RFQ had to be modified to solve the cooling problem at cw-operation, the geometrical precision had to be improved as well as the rf-contacts. The developments led to a new layout and a sophisticated production procedure of the stems and the electrodes. Calculations show an improved Rp-value leading to powerlosses of ca. 25 kW/m only, which is about half of the powerlosses which could be achieved safely at cw-operation of the similar Saraf-RFQ. Thermal measurements and simulations with the single components are in progress. The temperature distribution in cw-operation will be measured and the rf-performance checked.

THPB049	Tuning Studies on 4-Rod-RFQs	rfq, linac, resonance, coupling	963
	J.S. Schmidt, B. Klump, B. Koubek, A. Schempp IAP, Frankfurt am Main, Germany
	A NI LabVIEW based Tuning Software has been devel- oped to structure the tuning process of 4-rod Radio Fre- quency Quadrupole s (RFQs). Its results are compared to measurement data of 4-rod RFQs in different frequency ranges. For the optimization of RFQ design parameters, a certain voltage distribution along the electrodes of an RFQ is assumed. Therefore an accurate tuning of the voltage distribution is very important for the beam dynamic prop- erties of an RFQ. A variation can lead to particle losses and reduced beam quality especially at higher frequencies. Our electrode design usually implies a constant longitudi- nal voltage distribution. For its adjustment tuning plates are used between the stems of the 4-rod-RFQ. These pre- dictions are based, in contrast to other simulations, on mea- surements to define the characteristics of the RFQ as it was build - not depending on assumptions of the design. This will lead to a totally new structured process of tuning 4- rod-RFQs in a broad range of frequencies by using the pre- dictions of a software. The results of these studies are pre- sented in this paper.

THPB050	RFQ With Improved Energy Gain	rfq, acceleration, ion, emittance	966
	A. Kolomiets ITEP, Moscow, Russia A.S. Plastun MEPhI, Moscow, Russia
	RFQ structure is practically only one choice for using in front ends of ion linacs for acceleration up to energy about 3 MeV. This limit is due to its relatively low acceleration efficiency. However it isn’t intrinsic feature of RFQ principle. It is defined only by vane geometry of conventional RFQ structure with sinusoidal modulation of vanes. The paper presents results of analysis RFQ with modified vane geometries that allow to improve acceleration efficiency. RFQ with modified vanes was used for design second section of heavy ion injector of TWAC for acceleration of ions with Z/A = 0.33 up to 7 MeV/u.

THPB052	Recent Progress with the J-PARC RFQs	rfq, linac, emittance, vacuum	972
	Y. Kondo, K. Hasegawa, T. Morishita JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan H. Kawamata, F. Naito, T. Sugimura KEK, Ibaraki, Japan
	In this paper, we will report recent topics about J-PARC RFQs. First, the operating RFQ (RFQ I) have been recovered from the long shutdown due to the earthquake. This RFQ have been suffered from breakdown problem since 2008, therefore we have been developing a back-up RFQ (RFQ II). In April 2012, the high power test was successfully performed. Finally, we are fabricating a new RFQ for the beam-current upgrade of the J-PARC linac (RFQ III). The status of these RFQs are described.

THPB055	Numerical Simulations of ProjectX/PXIE RFQ	rfq, linac, emittance, space-charge	975
	J.-F. Ostiguy, A. Saini, N. Solyak Fermilab, Batavia, USA
	Funding: Fermi Research Alliance, LLC under DOE Contract No. De-AC02-07CH11359 Project-X is a proposed superconducting linac-based high intensity proton source at Fermilab. The machine first stages operate in CW mode from 2.1 to 3 GeV and a high bandwidth chopper is used to produce the required bunch patterns. A 162.5 MHz CW RFQ accelerates the beam from 30 keV to 2.1 MeV. A concern with CW operation is that losses either within the RFQ or in the dowstream modules should be well-understood and remain very low to ensure safe and/or reliable operation. In this contribution, we investigate the suitability of existing RFQ codes and model the PXIE RFQ (ProjectX test facility) designed constructed by LBNL to make useful predictions of loss patterns and phase space distribution.

THPB061	Experimental and Simulation Study of the Long-path-length Dynamics of a Space-charge-dominated Bunch	space-charge, electron, emittance, focusing	978
	I. Haber, B.L. Beaudoin, S. Bernal, R.A. Kishek, T.W. Koeth, Y. Mo UMD, College Park, Maryland, USA
	Funding: Work supported by the United States Department of Energy and the Office of Naval Research. The University of Maryland Electron Ring (UMER) is a low-energy (10 keV) electron facility built to study, on a scaled machine, the long-propagation-length evolution of a space-charge-dominated beam. Though constructed in a ring geometry to achieve a long path length at modest cost, UMER has observed important space-charge physics directly relevant to linear machines. Examples will be presented that emphasize studies of the longitudinal dynamics and comparisons to axisymmetric simulations. The detailed agreement obtained between simulation and experiment will be presented as evidence that the longitudinal physics observed is not strongly influenced by the ring geometry. Novel phenomena such as soliton formation, unimpeded bunch-end interpenetration, and an instability that occurs after this interpenetration, will be discussed.

THPB063	Simulated Performance of the CARIBU EBIS Charge Breeder Transport Line	ion, emittance, diagnostics, electron	984
	C. Dickerson, S.A. Kondrashev, B. Mustapha, P.N. Ostroumov ANL, Argonne, USA
	Funding: This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under contract number DE-AC02-06CH11357. An Electron Beam Ion Source (EBIS) has been designed and is being built to charge breed ions from the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) for post acceleration in the Argonne Tandem Linear Accelerator System (ATLAS). The calculated transverse acceptance of the EBIS charge breeder can approach the emittance of the injected ion beam, so beam distortion during transport could lead to incomplete injection and a decrease in the overall system efficiency. The beam quality can be maintained for simulations of the transport line using the ideal ion beam parameters. This paper reports the results of the electrostatic and ion beam transport simulations used to minimize the ion beam distortions by optimizing component designs and configurations.

THPB064	Beam Dynamics Tools for Linacs Design	electron, beam-loading, linac, synchrotron	987
	A.S. Setty THALES, Colombes, France
	In the last 25 years, we have been using our in house 3D code PRODYN * for electron beam simulations. We have also been using our in house code SECTION for the design of the travelling wave accelerating structures and the beam loading compensation. PRODYN follows in time, the most complicated electron trajectories with relativistic space-charge effects. This code includes backward as well as forwards movements. This paper will describe those two codes and will give some simulations and measurements results. * D. Tronc and A. Setty, Electrons RF auto-focusing and capture in bunchers, Linear Accelerator Conference 1988, Virginia.

THPB065	Status of the Beam Dynamics Code DYNAC	dipole, rfq, emittance, quadrupole	990
	E. Tanke, J.A. Rodriguez, W. Wittmer, X. Wu FRIB, East Lansing, Michigan, USA S. Valero CEA, Gif-sur-Yvette, France D. Wang NSCL, East Lansing, Michigan, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 The beam dynamics code DYNAC* was originally developed at CERN. For accelerating elements a set of very accurate quasi-Liouvillian beam dynamics equations was introduced, applicable to protons, heavy ions and non-relativistic electrons. Furthermore, DYNAC contains three space charge routines, including a 3D version*. More recently, a numerical method has been added, capable of simulating a multi charge state ion beam in accelerating elements (i.e. cavities). Beam line devices such as sextupoles and quadrupole-sextupole magnets as well as electrostatic devices are now also included. Capability of second order calculations of such elements for a multi charge state beam has been implemented. Benchmarking of the code, in particular for a multi-charge state beam is discussed. Comparison of beam simulations results with beam measurements on the MSU ReAccelerator (ReA) are reported. The possibility of using DYNAC as an online tool for ReA and FRIB is discussed. DYNAC: A Multi-Particle Beam Dynamics Code for Leptons and Hadrons, E.Tanke et al,LINAC2002 **HERSC: A New 3 Dimensional Space Charge Routine for High Intensity Bunched Beams, E.Tanke et al,LINAC2002

THPB094	Performance of Beam Chopper at SARAF via RF Deflector Before the RFQ	rfq, ion, proton, ion-source	1038
	A. Shor, D. Berkovits, I. Fishman, A. Grin, B. Kaizer, L. Weissman Soreq NRC, Yavne, Israel
	We describe performance of a beam chopper at the SARAF accelerator consisting of an HV deflector preceding the RFQ. The deflector and electronics, developed at LNS Catania, was designed to provide slow beam chopping for beam testing and diagnostics where low beam power is necessary. The HV deflector sweeps away the low energy beam onto a water cooled beam catcher, while a fast HV switch momentarily switches off the HV whenever a transmitted beam to the RFQ is desired. We report on measurements with this chopping system, where minimum transmitted beam pulse of 180 ns duration is attained with a rise and fall time of several nano-seconds. We performed beam dynamics simulations of SARAF Phase-I, including the deflector, where the short rise and fall times of the chopped beam is attributed to the tight collimation of the deflected beam provided by the RFQ and the fast Faraday Cup. We also describe beam dynamics simulations which suggest that single RFQ bunch selection can be achieved with the existing chopping system, during zero-crossover for positive-negative deflecting HV waveform.

THPB095	Designing of a Phase-mask-type Laser Driven Dielectric Accelerator for Radiobiology	laser, electron, acceleration, vacuum	1041
	K. Koyama UTNL, Ibaraki, Japan A. Aimidura, M. Uesaka The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan Y. Matsumura University of Tokyo, Tokyo, Japan T. Natsui, M. Yoshida KEK, Ibaraki, Japan
	Funding: This work is supported by KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120 In order to estimate the health risk of a low radiation dose, basic processes of the radiobiology should be clarified by shooting a DNA using a spatially and temporary defined particle beam or X-ray. A suitable beam size is as small as a resolving power of an optical microscope of a few hundred nanometers. Photonic crystal accelerators (PCA) are capable of delivering nm-beams of sub-fs pulses because the characteristic length and frequency of PCAs are on the order of the laser light. Since the phase-mask type accelerator has a simpler structure than other types of PCAs, we are designing a phase-mask type laser driven dielectric accelerator. By adopting an unbalanced length of pillar and ditch (grating) of 4:1, a standing wave like acceleration field is produced in a acceleration channel. A pillar height and initial speed of injected electron are determined by analytically. The maximum acceleration gradient of 2 GeV/m is estimated. The required laser power is roughly estimated to be 6.5 GW. The simulation using CST-code also shows similar values to accelerate electrons by the phase-mask type accelerator.

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SUPB003

Feasibility Study of Short Pulse Mode Operation for Multi-turn ERL Light Source

linac, emittance, undulator, acceleration

4

T. Atkinson, A.V. Bondarenko, A.N. Matveenko, Y. Petenev
HZB, Berlin, Germany

The optics and simulation group at HZB are designing Germany’s future light source. Based on the emerging Energy Recovery Linac super conducting technology, the Femto-Science-Factory (FSF) will provide its users with ultra-bright photons of Angstrom wavelength at 6 GeV. The FSF is intended to be a multi-user facility and offer a wide variety of operation modes. A low emittance ~0.1 μm rad mode will operate in conjunction with a short-pulse ~10 fs mode. This paper highlights the physical limitations when trying to offer interchangeable modes and preserve beam high quality.

SUPB006

Study of Beam-Based Alignment for Shanghai Soft X-Ray FEL Facility

linac, emittance, alignment, FEL

10

D. Gu, Q. Gu, D. Huang, M. Zhang, M.H. Zhao
SINAP, Shanghai, People's Republic of China

In linear accelerators, dispersion caused by quadrupole misalignment and transverse wake-field effect caused by alignment errors of accelerate structures will lead to a significant emittance growth. There are more stringent restrictions on SXFEL, the traditional optical alignment can no longer meet its requirements, but the Beam-Based Alignment(BBA) method allows more precise alignment, further reduce the Linac errors to meet SXFEL requirements .In undulator sections, orbit changes are not only caused by misalignments of quadrupole magnet position ,but also the errors of undulator magnetic. In order to achieve alignment accuracy over longer distance, we measuring BPM data under different conditions and using SVD algorithm for calculation and analysis, we can get the quadrupole magnet errors and BPM offset. With the method above, software based on MATLAB has been designed and compared the results with other software.

SUPB007

On-Line Dispersion Free Steering for the Main Linac of CLIC

emittance, ground-motion, feedback, linac

13

J. Pfingstner, D. Schulte
CERN, Geneva, Switzerland

For future linear colliders as well as for light sources, ground motion effects are a severe problem for the accelerator performance. After a few minutes, orbit feedback systems are not sufficient to mitigate all ground motion effects and additional long term methods will have to be deployed. In this paper, the long term ground motion effects in the main linac of the Compact Linear Collider (CLIC) are analysed via simulation studies. The primary growth of the projected emittance is identified to originate from chromatic dilutions due to dispersive beam orbits. To counter this effect, an on-line identification algorithm is applied to measure the dispersion parasitically. This dispersion estimate is used to correct the beam orbit with an iterative dispersion free steering algorithm. The presented results are not only of interest for the CLIC project, but for all linacs in which the dispersive orbit has to be corrected over time.

SUPB011

Computational Model Analysis for Experimental Observation of Optical Current Noise Suppression Below the Shot-noise Limit

plasma, electron, linac, beam-transport

25

A. Nause, A. Gover
University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel

Funding: We acknowledge support of the Israel Science Foundation grant
We report first demonstration of optical frequency current shot-noise suppression in a relativistic e-beam. This process is made possible by collective Coulomb interaction between the electrons of a cold intense beam during beam drift, and is essentially a process of longitudinal beam-plasma oscillation [1]. Suppression of beam current noise below the classical “shot-noise” level has been known in the microwave tubes art [2]. This is the first time that it is demonstrated in the optical regime. We predict that the scheme can be extended to the XUV and possibly to shorter wavelengths with further development of technology. The fundamental current shot-noise determines the level of incoherent spontaneous radiation emission from electron-beam optical radiation sources and SASE-FELs [3]. Suppressing shot-noise would make it possible to attain spontaneous emission sub-radiance [4] and surpass the classical coherence limits of seed-injected FELs. The effect was demonstrated by measuring sub-linear growth as a function of current of the OTR Radiation. This finding indicates that the beam charge homogenizes due to the collective interaction, and its distribution becomes sub-Poissonian.
[1] A. Gover, E. Dyunin, PRL, 102, 154801, 2009
[2] H. Haus, N. Robinson, Proc. IRE, 43, 981 (1955)
[3] P. Emma, et al , Nature Photonics 4, 641 (2010)
[4] A. Dicke, Phys. Rev. 93, 99 (1954)

SUPB013

The Beam Commissioning Plan of Injector II in C-ADS

rfq, cavity, proton, diagnostics

32

Z.J. Wang, Y. He, H. Jia, C. Li, S.H. Liu, W. Wu, X.B. Xu, B. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

The design work of the Injector II, which is 10 MeV proton linac, in C-ADS project is being finished and some key elements are being fabricated. Now it is necessary to definite the operation mode of beam commissioning, including the selection of the beam current, pulse length and repetition frequency. Also the beam commissions plan should be specified. The beam commissions procedures is simulated with t-mode code GPT. In this paper, the general beam commissioning plan of Injector II in CIADS and simulation results of commissions procedures are presented.

SUPB014

RF Setup of the MedAustron RFQ

rfq, resonance, ion, pick-up

35

B. Koubek, A. Schempp, J.S. Schmidt
IAP, Frankfurt am Main, Germany
J. Haeuser
Kress GmbH, Biebergemuend, Germany

A Radio Frequency Quadrupole (RFQ) was built for the injector of the cancer treatment facility MedAuston in Austria. For the RF design simulations were performed using CST Microwave Studio and the structure was manufactured by Firma Kress in Biebergemuend, Germany. The simulations and the RF setup of the delivered RFQ are presented in this paper.

SUPB016

RFQ With Improved Energy Gain

rfq, acceleration, ion, emittance

41

A. Kolomiets
ITEP, Moscow, Russia
A.S. Plastun
MEPhI, Moscow, Russia

RFQ structure is practically only one choice for using in front ends of ion linacs for acceleration up to energy about 3 MeV. This limit is due to its relatively low acceleration efficiency. However it isn’t intrinsic feature of RFQ principle. It is defined only by vane geometry of conventional RFQ structure with sinusoidal modulation of vanes. The paper presents results of analysis RFQ with modified vane geometries that allow to improve acceleration efficiency. RFQ with modified vanes was used for design second section of heavy ion injector of TWAC for acceleration of ions with Z/A = 0.33 up to 7 MeV/u.

SUPB017

Tuning Studies on 4-rod-RFQs

rfq, linac, resonance, coupling

44

J.S. Schmidt, B. Klump, B. Koubek, A. Schempp
IAP, Frankfurt am Main, Germany

A NI LabVIEW based Tuning Software has been devel- oped to structure the tuning process of 4-rod Radio Fre- quency Quadrupole s (RFQs). Its results are compared to measurement data of 4-rod RFQs in different frequency ranges. For the optimization of RFQ design parameters, a certain voltage distribution along the electrodes of an RFQ is assumed. Therefore an accurate tuning of the voltage distribution is very important for the beam dynamic prop- erties of an RFQ. A variation can lead to particle losses and reduced beam quality especially at higher frequencies. Our electrode design usually implies a constant longitudi- nal voltage distribution. For its adjustment tuning plates are used between the stems of the 4-rod-RFQ. These pre- dictions are based, in contrast to other simulations, on mea- surements to define the characteristics of the RFQ as it was build - not depending on assumptions of the design. This will lead to a totally new structured process of tuning 4- rod-RFQs in a broad range of frequencies by using the pre- dictions of a software. The results of these studies are pre- sented in this paper.

SUPB018

Studies of Parasitic Cavity Modes for Proposed ESS Linac Lattices

linac, cavity, proton, lattice

47

R. Ainsworth
Royal Holloway, University of London, Surrey, United Kingdom
S. Molloy
ESS, Lund, Sweden

The European Spallation Source (ESS) planned for construction in Lund, Sweden, will be the worlds most intense source of pulsed neutrons. The neutrons will be generated by the collision of a 2.5 GeV proton beam with a heavy-metal target. The superconducting section of the proton linac is split into three different types of cavities, and a question for the lattice designers is at which points in the beamline these splits should occur. This note studies various proposed designs for the ESS lattice from the point of view of the effect on the beam dynamics of the parasitic cavity modes lying close in frequency to the fundamental accelerating mode. Each linac design is characterised by the initial kinetic energy of the beam, as well as by the velocity of the beam at each of the points at which the cavity style changes. The scale of the phase-space disruption of the proton pulse is discussed, and some general conclusions for lattice designers are stated.

SUPB019

The Multipacting Simulation for the New-Shaped QWR using TRACK3P

cavity, accelerating-gradient, electron, niobium

50

C. Zhang, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, S.H. Zhang, S.X. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

In order to improve the electro-magnetic performance of the quarter wave resonator, a new-shaped cavity with an elliptical cylinder outer conductor has been proposed. This novel cavity design can provide much lower peak surface magnetic field and much higher Ra/Q0 and G. The Multipacting simulation has been done for this new QWR cavity using ACE3P/TRACK3P code, in this paper the simulation results will be presented and analyzed.

SUPB020

Structural Analysis of the New-Shaped QWR for HIAF in IMP

cavity, superconducting-cavity, SRF, controls

53

C. Zhang, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, Y.Z. Yang, W.M. Yue, S.H. Zhang, S.X. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China
M.H. Xu
IHEP, Beijing, People's Republic of China

Since the QWR cavity is very successful for the operation with frequency of 48 to 160 MHz and beta value of 0.001 to 0.2, a new-shaped QWR is being designed for the low energy superconducting section of HIAF in the Institute of Modern Physics. The cavity will work at 81.25 MHz and \beta of 0.085，with a elliptical cylinder outer conductor to better its electro-magnetic performance and keep limited accelerating space. Structural design is an important aspect of the overall cavity implementation, and in order to minimize the frequency shift of the cavity due to the helium bath pressure fluctuations, the Lorentz force and microphonic excitation, stiffening elements have to be applied. In this paper, structural analyses of the new-shaped QWR are presented and stiffening methods are explored.

SUPB022

First Measurements on the 325 MHz Superconducting CH Cavity

cavity, controls, linac, coupling

56

M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany
M. Amberg
HIM, Mainz, Germany
W.A. Barth, S. Mickat
GSI, Darmstadt, Germany
M. Pekeler
RI Research Instruments GmbH, Bergisch Gladbach, Germany

Funding: Work supported by HIM, GSI, BMBF Contr. No. 06FY161I
At the Institute for Applied Physics (IAP), Frankfurt University, a superconducting 325 MHz CH-Cavity has been designed and built. This 7-cell cavity has a geometrical \beta of 0.16 corresponding to a beam energy of 11.4 AMeV. The design gradient is 5 MV/m. Novel features of this resonator are a compact design, low peak fields, easy surface processing and power coupling. Furthermore a new tuning system based on bellow tuners inside the resonator will control the frequency during operation. After successful rf tests in Frankfurt the cavity will be tested with a 10 mA, 11.4 AMeV beam delivered by the GSI UNILAC. In this paper first measurements and corresponding simulations will be presented.

SUPB023

Status of the Superconducting CW Demonstrator for GSI

cavity, linac, solenoid, cryogenics

59

F.D. Dziuba, M. Amberg, M. Busch, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany
K. Aulenbacher
IKP, Mainz, Germany
W.A. Barth, S. Mickat
GSI, Darmstadt, Germany

Funding: Helmholtz Institut Mainz (HIM), GSI, BMBF Contr. No. 06FY7102
Since the existing UNILAC at GSI will be used as an injector for the FAIR facility a new superconducting (sc) continous wave (cw) LINAC is highly requested by a broad community of future users to fulfil the requirements of nuclear chemistry, especially in the research field of Super Heavy Elements (SHE). This LINAC is under design in collaboration with the Institute for Applied Physics (IAP) of Frankfurt University, GSI and the Helmholtz Institut Mainz (HIM). It will consist of 9 sc Crossbar-H-mode (CH) cavities operated at 217 MHz which provide an energy up to 7.3 AMeV. Currently, a prototype of the cw LINAC is under development. This demonstrator comprises the first sc CH cavity of the LINAC embedded between two sc solenoids mounted in a horizontal cryomodule. One important milestone of the project will be a full performance test of the demonstrator by injecting and accelerating a beam from the GSI High Charge State Injector (HLI) in 2014. The status of the demonstrator is presented.

SUPB024

Development of Permanent Magnet Focusing System for Klystrons

klystron, focusing, permanent-magnet, cathode

62

Y. Fuwa, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
S. Fukuda, S. Michizono
KEK, Ibaraki, Japan

The Distributed RF System (DRFS) for the International Linear Collider (ILC) requires thousands of klystrons. The failure rate of the power supply for solenoid focusing coil of each klystron may be a critical issue for a regular operation of the ILC. A permanent magnet beam focusing system can increase reliability and eliminate their power consumption. Since the required magnetic field is not high in this system, inexpensive anisotropic ferrite magnets can be used instead of magnets containing rare earth materials. In order to prove its feasibility, a test model of a permanent magnet focusing beam system is constructed and a power test of the klystron for DRFS with this model is under preparation. The results of magnetic field distribution measurement and the power test will be presented.

SUPB026

Multipacting Analysis of High-velocity Superconducting Spoke Resonators

electron, cavity, site, superconductivity

68

C.S. Hopper, J.R. Delayen
ODU, Norfolk, Virginia, USA

Some of the advantages of superconducting spoke cavities are currently being investigated for the high-velocity regime. When determining a final, optimized geometry, one must consider the possible limiting effects multipacting could have on the cavity. We report on the results of analytical calculations and numerical simulations of multipacting electrons in superconducting spoke cavities and methods for reducing their impact.

SUPB027

Mechanical Study of the First Superconducting Half-wave Resonator for Injector II of CADS Project

cavity, HOM, controls, cryomodule

71

S. He, Y. He, S.C. Huang, F.F. Wang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

Funding: This work is Supported by the National Natural Science Foundation of China (Grant Agreement 91026001)
Within the framework of the China Accelerator-Driven Sub-critical Systems (CADS) project, Institute of Modern Physics (IMP) Chinese Academic of Sciences has proposed a 162.5 MHz Half-Wave Resonator (HWR) Superconducting cavity for low energy section (β=0.09) of high power proton linear accelerators as a new injector II for CIADS. For the geometrical design of superconducting cavities structure mechanical simulations are essential to predict mechanical eigenmodes and the deformation of the cavity walls due to bath pressure effects and the cavity cool-down. Additionally, the tuning analysis has been investigated to control the frequency against microphonics and Lorentz force detuning. Therefore, several RF, static structure, thermal and modal analysis with a three-dimensional Finite-Element Method (FEM) code Traditional ANSYS have been performed.

SUPB028

The Superconducting CH Cavity Development in IMP*

cavity, linac, niobium, resonance

74

M.X. Xu, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, Z.J. Wang, J.W. Xia, Y.Z. Yang, W.M. Yue, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

Funding: Work supported by 91026001 Nature Science Foundation of China
The Cross-Bar H-type (CH) cavity is a multi-gap drift tube structure operated in the H21 mode [1]. The Institute of Modern Physics (IMP) has been doing research and development on this type of superconducting CH cavity which can work at the C-ADS (accelerator driver sub-critical system of China). A new geometry CH cavity has been proposed which have smaller radius. It’s suitable in fabrication, and it’s can reduce cost too .Detailed numerical simulations with CST MicroWave Studio have been performed. An overall surface reduction of 30% against the old structure seems feasible. A copper model CH cavity is being fabrication for validating the simulations and the procedure of fabricating niobium cavity.

SUPB032

The C-band RF Pulse Compression for Soft XFEL at SINAP

cavity, coupling, klystron, free-electron-laser

83

C.P. Wang, Q. Gu, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

A compact soft X-ray free electron laser facility is presently being constructed at shanghai institute of applied physics (SINAP), Chinese academy of science in 2012 and will be accomplished in 2014. This facility requires a compact linac with a high-gradient accelerating structure for a limited overall length less than 230 m. The c-band technology which is already used in KEK/Spring-8 linear accelerator is a good compromise for this compact facility and a c-and traveling-wave accelerating structure was already fabricated and tested at SINAP, so a c-band pulse compression will be required. AND a SLED type RF compression scheme is proposed for the C-band RF system of the soft XFEL and this scheme uses TE0.1.15 mode energy storage cavity for high Q-energy storage. The C-band pulse compression under development at SINAP has a high power gain about 3.1 and it is designed to compress the pulse width from 2.5 μs to 0.5 μs and multiply the input RF power of 50 MW to generate 160 MW peak RF power, and the coupling coefficient will be 8.5. It has three components: 3 dB coupler, mode convertors and the resonant cavities.

MO3A04

Accelerator/Decelerator of Slow Neutrons

neutron, focusing, controls, dipole

133

M. Kitaguchi
Kyoto University, Research Reactor Institute, Osaka, Japan
Y. Arimoto, H.M. Shimizu
KEK, Ibaraki, Japan
P.W. Geltenbort
ILL, Grenoble, France
S. Imajo
Kyoto University, Kyoto, Japan
Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
Y. Seki
RIKEN Nishina Center, Wako, Japan
T. Yoshioka
Kyushu University, Fukuoka, Japan

Funding: Supported by the Quantum Beam Fundamentals Development Program MEXT, a Grant-in-Aid for Creative Scientific Research of MEXT Program No.19GS0210 and No.23244047, Yamada Science Foundation, and KEK.
An accelerator/decelerator for slow neutron beams has been demonstrated. The energy of a neutron can be increased or decreased by flipping the neutron spin (directly coupled to magnetic dipole moment) in magnetic field. This device is a combination of a gradient magnetic field and an RF magnetic field. Because the RF frequency for the spin flip is a function of the external magnetic field, only neutrons that are located in a specific magnetic field level will be spin-flipped at a given RF frequency. By changing the RF frequency, the energy change can be selected in the gradient magnetic field. The maximum field of the gradient magnet is 1 T, which corresponds to the energy change of 120 neV. The magnetic field linearly decreases to 0.2T within 25 cm. By putting this device on a beamline from a pulsed neutron source, neutron rebuncher is realized. The dense slow neutrons are important to suppress the systematic errors for the measurement of neutron electric dipole moment (nEDM). The combination of spallation neutron source and this neutron rebuncher is suitable to the measurement of nEDM. A review of current status of our plan for nEDM experiment at J-PARC will be also presented.

Slides MO3A04 [3.750 MB]

MOPLB04

A 10 MeV L-band Linac for Irradiation Applications in China

linac, electron, gun, klystron

147

G. Pei, Y.L. Chi, M.H. Dai, D.Y. He, X. He, X. Li, J. Liu, C. Ma, X. Wang, C.H. Yu, F. Zhao, J. Zhao, Z.S. Zhou
IHEP, Beijing, People's Republic of China
Y. Feng, H. Huang, S. Shi, E. Tang, X. Yang, Q. Yuan, Z. Zhu
Institute of High Energy Physics (IHEP), People's Republic of China
Z. Li, X. Zhang
Wuxi EL PONT Radiation Technology Ltd, Wuxi, People's Republic of China

The electron linear accelerator has wide applications, and the demands are keeping growing for the irradiation applications in China. A high beam power 10 MeV L-band Linac has been developed recently as a joint venture of Institute of High Energy Physics and EL-PONT Company. The Thales TH2104U klystron, 3 A thermionic electron gun and three meter L-band disk-loaded constant impedance RF structure are adopted. A stable electron beam of 10 MeV, 40 kW has been obtained in the last May with a microwave to beam efficiency of about 65%. In this paper we will present the detailed design issues and beam commissioning.

Slides MOPLB04 [1.800 MB]

MOPLB12

X-Ray Local Energy Spectrum Measurement on Tsinghua Thomson Scattering X-Ray Source (TTX)

scattering, electron, laser, photon

171

Y.-C. Du, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, H. Zha, Z. Zhang
TUB, Beijing, People's Republic of China

Thomson scattering X-ray source, in which the TW laser pulse is scattered by the relativistic electron beam, can provide ultra short, monochromatic, high flux, tunable polarized hard X-ray pulse which is can widely used in physical, chemical and biological process research, ultra-fast phase contrast imaging, and so on. Since the pulse duration of X-ray is as short as picosecond and the flux in one pulse is high, it is difficult to measure the x-ray spectrum. In this paper, we present the X-ray spectrum measurement experiment on Tsinghua Thomson scattering. The preliminary experimental results shows the maximum X-ray energy is about 47 keV, which is agree well with the simulations.

Slides MOPLB12 [1.311 MB]

MOPB007

Study of Microbunching Instabilitity in the Linac of the Shanghai Soft X-Ray Free Electron Laser Facility

linac, impedance, FEL, electron

189

D. Huang, Q. Gu, M. Zhang
SINAP, Shanghai, People's Republic of China

The microbunching instability in the LINAC of a FEL facility has always been an issue which may degrade the quality of the electron beam. As the result, the whole facility may not be working properly. Shanghai soft X-ray FEL project (SXFEL), which is planned to start construction by the end of 2012, will be the first X-ray FEL facility in China. In this article, detailed study will be given based on the physical design of the facility to gain better understanding and control over the possible microbunching instability in SXFEL, which is critical to the success of the project. Moreover, the contribution of the possible plasma effects to the instability will also be studied by modifying the physical model of the longitudinal space charge (LSC) impedance.

MOPB022

RF Characteristic Studies on the Whole Accelerating Structure for the BEPCII Linear Accelerator

linac, vacuum, impedance, electromagnetic-fields

219

S. Pei, M. Hou, X. Li, J.R. Zhang
IHEP, Beijing, People's Republic of China
B.L. Wang
SINAP, Shanghai, People's Republic of China

An accelerating structure is one device to boost the particle energy. 2856 MHz 3 m long travelling wave disk-loaded accelerating structure is applied in BEPCII linac, its RF characteristics are mainly determined by the 84 regular cells located between the input and output couplers. Input and output couplers need to be included when the whole structure RF characteristics are simulated before fabrication; otherwise it would be difficult to obtain the travelling wave fields excited in the whole structure. If the real 3D couplers are modelled during the design process, a large amount of computer resources and time need to be used. However, if the redesigned azimuth symmetric coupler is used to replace the real 3D one during the simulation process, much less computer resources and time are required. With this method proposed here, the simulation results agree well with the theoretically calculated and experimentally measured ones.
*peisl@ihep.ac.cn

MOPB036

Feasibility Study of Short Pulse Mode Operation for Multi-turn ERL Light Source

linac, emittance, undulator, acceleration

255

T. Atkinson, A.V. Bondarenko, A.N. Matveenko, Y. Petenev
HZB, Berlin, Germany

The optics and simulation group at HZB are designing Germany’s future light source. Based on the emerging Energy Recovery Linac super conducting technology, the Femto-Science-Factory (FSF) will provide its users with ultra-bright photons of Angstrom wavelength at 6 GeV. The FSF is intended to be a multi-user facility and offer a wide variety of operation modes. A low emittance ~0.1 μm rad mode will operate in conjunction with a short-pulse ~10 fs mode. This paper highlights the physical limitations when trying to offer interchangeable modes and preserve beam high quality.

MOPB042

On-line Dispersion Free Steering for the Main Linac of CLIC

emittance, ground-motion, feedback, linac

267

J. Pfingstner, D. Schulte
CERN, Geneva, Switzerland

For future linear colliders as well as for light sources, ground motion effects are a severe problem for the accelerator performance. After a few minutes, orbit feedback systems are not sufficient to mitigate all ground motion effects and additional long term methods will have to be deployed. In this paper, the long term ground motion effects in the main linac of the Compact Linear Collider (CLIC) are analysed via simulation studies. The primary growth of the projected emittance is identified to originate from chromatic dilutions due to dispersive beam orbits. To counter this effect, an on-line identification algorithm is applied to measure the dispersion parasitically. This dispersion estimate is used to correct the beam orbit with an iterative dispersion free steering algorithm. The presented results are not only of interest for the CLIC project, but for all linacs in which the dispersive orbit has to be corrected over time.

MOPB046

A 10 MeV L-band Linac for Irradiation Applications in China

linac, electron, gun, klystron

276

G. Pei, Y.L. Chi, M.H. Dai, D.Y. He, X. He, X. Li, J. Liu, C. Ma, X. Wang, X.W. Yang, C.H. Yu, F. Zhao, J. Zhao, Z.S. Zhou
IHEP, Beijing, People's Republic of China
Y. Feng, H. Huang, S. Shi, E. Tang, X. Yang, Q. Yuan, Z. Zhu
Institute of High Energy Physics (IHEP), People's Republic of China
Z. Li, X. Zhang
Wuxi EL PONT Radiation Technology Ltd, Wuxi, People's Republic of China

The electron linear accelerator has wide applications, and the demands are keeping growing for the irradiation applications in China. A high beam power 10 MeV L-band Linac has been developed recently as a joint venture of Institute of High Energy Physics and EL-PONT Company. The Thales TH2104U klystron, 3 A thermionic electron gun and three meter L-band disk-loaded constant impedance RF structure are adopted. A stable electron beam of 10 MeV, 40 kW has been obtained in the last May with a microwave to beam efficiency of about 65%. In this paper we will present the detailed design issues and beam commissioning.

MOPB056

Multipacting Analysis of High-Velocity Superconducting Spoke Resonators

electron, cavity, site, superconductivity

303

C.S. Hopper, J.R. Delayen
ODU, Norfolk, Virginia, USA

Some of the advantages of superconducting spoke cavities are currently being investigated for the high-velocity regime. When determining a final, optimized geometry, one must consider the possible limiting effects multipacting could have on the cavity. We report on the results of analytical calculations and numerical simulations of multipacting electrons in superconducting spoke cavities and methods for reducing their impact.

MOPB057

Mechanical Study of the First Superconducting Half-wave Resonator for Injector II of CADS Project

cavity, HOM, controls, cryomodule

306

S. He, Y. He, S.C. Huang, F.F. Wang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

Funding: This work is Supported by the National Natural Science Foundation of China (Grant Agreement 91026001)
Within the framework of the China Accelerator-Driven Sub-critical Systems (CADS) project, Institute of Modern Physics (IMP) Chinese Academic of Sciences has proposed a 162.5 MHz Half-Wave Resonator (HWR) Superconducting cavity for low energy section (β=0.09) of high power proton linear accelerators as a new injector II for CIADS. For the geometrical design of superconducting cavities structure mechanical simulations are essential to predict mechanical eigenmodes and the deformation of the cavity walls due to bath pressure effects and the cavity cool-down. Additionally, the tuning analysis has been investigated to control the frequency against microphonics and Lorentz force detuning. Therefore, several RF, static structure, thermal and modal analysis with a three-dimensional Finite-Element Method (FEM) code Traditional ANSYS have been performed.

MOPB059

The Superconducting CH Cavity Development in IMP*

cavity, linac, niobium, resonance

309

M.X. Xu, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, Z.J. Wang, J.W. Xia, Y.Z. Yang, W.M. Yue, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

Funding: Work supported by 91026001 Nature Science Foundation of China
The Cross-Bar H-type (CH) cavity is a multi-gap drift tube structure operated in the H21 mode [1]. The Institute of Modern Physics (IMP) has been doing research and development on this type of superconducting CH cavity which can work at the C-ADS (accelerator driver sub-critical system of China). A new geometry CH cavity has been proposed which have smaller radius. It’s suitable in fabrication, and it’s can reduce cost too .Detailed numerical simulations with CST MicroWave Studio have been performed. An overall surface reduction of 30% against the old structure seems feasible. A copper model CH cavity is being fabrication for validating the simulations and the procedure of fabricating niobium cavity.

MOPB072

Multipole Expansion of the Fields in Superconducting High-Velocity Spoke Cavities

cavity, multipole, quadrupole, linac

345

R.G. Olave, J.R. Delayen, C.S. Hopper
ODU, Norfolk, Virginia, USA

Multi-spokes superconducting cavities in the high-beta regime are being considered for a number of applications. In order to accurately model the dynamics of the particles in such cavities, knowledge of the fields off-axis are needed. We present a study of the multipoles expansion of the fields from an EM simulation field data for a two-spoke cavity operating at 325 MHz, β = 0.82 and 500 MHz, β = 1.

MOPB074

Thermo-Mechanical Simulations of the Frequency Tuning Plunger for the IFMIF Half-Wave Resonator

niobium, cavity, vacuum, cryomodule

351

N. Bazin, P. Bosland, S. Chel, G. Devanz, N. Grouas, P. Hardy, J. Migne, F. Orsini, F. Peauger
CEA/DSM/IRFU, France

In the framework of the International Fusion Materials Irradiation Facility (IFMIF), a superconducting option has been chosen for the 5 MeV RF Linac of the first phase of the project (EVEDA), based on a cryomodule composed of 8 HWRs, 8 RF couplers and 8 Solenoid packages. The frequency tuning system of the IFMIF HWR is an innovated system based on a capacitive plunger installed in the electric field region allowing a large tuning range. Following the cold test results obtained on HWR equipped with the first design of plunger in 2011*, it was decided to develop a new design of a fully-niobium plunger. The paper will present the development of the new plunger concepts and the thermo-mechanical simulations. For the mechanical simulations, the aim is to sufficiently deform the plunger to tune the cavity while staying in the elastic range of the niobium material. For the thermal simulations, all the non-linear properties of the materials and the effects of the RF fields are taken into account: thermal conductivity and surface resistance are depending on the temperature, RF fields computed with dedicated software are leading to thermal dissipations in the materials and the vacuum seal.
* F. Orsini et al., “Vertical tests preliminary results of the IFMIF cavity prototypes and cryomodule development”, SRF 2011, Chigaco, USA

MOPB089

X-Ray Local Energy Spectrum Measurement at Tsinghua Thomson Scattering X-Ray Source (TTX)

scattering, electron, laser, photon

383

Y.-C. Du, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, H. Zha, Z. Zhang
TUB, Beijing, People's Republic of China

Thomson scattering X-ray source, in which the TW laser pulse is scattered by the relativistic electron beam, can provide ultra short, monochromatic, high flux, tunable polarized hard X-ray pulse which is can widely used in physical, chemical and biological process research, ultra-fast phase contrast imaging, and so on. Since the pulse duration of X-ray is as short as picosecond and the flux in one pulse is high, it is difficult to measure the x-ray spectrum. In this paper, we present the X-ray spectrum measurement experiment on Tsinghua Thomson scattering. The preliminary experimental results shows the maximum X-ray energy is about 47 keV, which is agree well with the simulations.

MOPB094

Simulation Study on the Longitudinal Bunch Shape Measurement by RF Chopper at J-PARC Linac

cavity, emittance, linac, DTL

395

T. Maruta
JAEA/J-PARC, Tokai-mura, Japan
M. Ikegami
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

A RF chopper is placed in the medium energy transport section (MEBT1) at J-PARC linac. The chopper is normally driven at synchronous phase of 0 degree to give a maximum deflection. The chopper has two RF gaps and both of them deflect a beam bunch horizontally while RF is on. In the MEBT1 section, while we have a transverse emittance monitor, there is no longitudinal monitor. It is hard to newly place a longitudinal beam monitor there due to space limitation. We conduct a simulation which studies on the usability of the chopper to a longitudinal beam monitor. When the synchronous phase of the chopper is ± 90 degree, the longitudinal beam profile is projected to horizontal beam distribution. In this presentation, we introduce simulation results.

MOPB098

Planning for Experimental Demonstration of Transverse Emittance Transfer at the GSI UNILAC through Eigen-Emittance Shaping

emittance, quadrupole, coupling, scattering

404

C. Xiao, O.K. Kester
IAP, Frankfurt am Main, Germany
L. Groening
GSI, Darmstadt, Germany

The minimum transverse emittances achievable in a beam line are determined by the two transverse eigen-emittances of the beam. For vanishing interplane correlations they are equal to the transverse rms-emittances. Eigen-emittances are constants of motion for all symplectic beam line elements, i.e. (even tilted) linear elements. To allow for rms-emittance transfer, the eigen-emittances are changed by a non-symplectic action to the beam, preferably preserving the 4d-rms-emittance. Unlike emittance swapping the presented concept will allow transforming a beam of equal rms-emittances into a beam of different rms-emittances while preserving the 4d-rms-emittance. This contribution will introduce the concept for eigen-emittance shaping and rms-emittance transfer at an ion linac. The actual work status towards the experimental demonstration of the concept at the GSI UNILAC is presented.

TUPLB05

Computational Model Analysis for Experimental Observation of Optical Current Noise Suppression below the Shot-Noise Limit

plasma, electron, linac, beam-transport

451

A. Gover
University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel
A. Nause
University of Tel Aviv, Tel Aviv, Israel

Funding: We acknowledge support of the Israel Science Foundation grant
We report first demonstration of optical frequency current shot-noise suppression in a relativistic e-beam. This process is made possible by collective Coulomb interaction between the electrons of a cold intense beam during beam drift, and is essentially a process of longitudinal beam-plasma oscillation [1]. Suppression of beam current noise below the classical “shot-noise” level has been known in the microwave tubes art [2]. This is the first time that it is demonstrated in the optical regime. We predict that the scheme can be extended to the XUV and possibly to shorter wavelengths with further development of technology. The fundamental current shot-noise determines the level of incoherent spontaneous radiation emission from electron-beam optical radiation sources and SASE-FELs [3]. Suppressing shot-noise would make it possible to attain spontaneous emission sub-radiance [4] and surpass the classical coherence limits of seed-injected FELs. The effect was demonstrated by measuring sub-linear growth as a function of current of the OTR Radiation. This finding indicates that the beam charge homogenizes due to the collective interaction, and its distribution becomes sub-Poissonian.
[1] A. Gover, E. Dyunin, PRL, 102, 154801, 2009
[2] H. Haus, N. Robinson, Proc. IRE, 43, 981 (1955)
[3] P. Emma, et al , Nature Photonics 4, 641 (2010)
[4] A. Dicke, Phys. Rev. 93, 99 (1954)

TUPLB12

Development of Permanent Magnet Focusing System for Klystrons

klystron, focusing, permanent-magnet, cathode

470

Y. Fuwa, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
S. Fukuda, S. Michizono
KEK, Ibaraki, Japan

The Distributed RF System (DRFS) for the International Linear Collider (ILC) requires thousands of klystrons. The failure rate of the power supply for solenoid focusing coil of each klystron may be a critical issue for a regular operation of the ILC. A permanent magnet beam focusing system can increase reliability and eliminate their power consumption. Since the required magnetic field is not high in this system, inexpensive anisotropic ferrite magnets can be used instead of magnets containing rare earth materials. In order to prove its feasibility, a test model of a permanent magnet focusing beam system is constructed and a power test of the klystron for DRFS with this model is under preparation. The results of magnetic field distribution measurement and the power test will be presented.

Slides TUPLB12 [1.357 MB]

TUPB001

The Fine Structure of the Zone of Particle Interaction with a Finite Length Periodic Structure

wakefield, impedance, diagnostics, emittance

473

V.V. Paramonov
RAS/INR, Moscow, Russia

The periodic constant impedance deflecting structures are widely used for a special beam diagnostic in FEL facilities. The method, based on frequency domain approach, was developed to estimate long range wake fields structure parameters in a wide frequency range. It is shown, that regardless to number of cells in the structure, at each passband to the zone of particle effective interaction with the structure belongs several, at least three modes. The usual time domain simulations provide the total estimation for loss factor or kick factor values and modes separation in the time domain approach requires enormous simulations.

TUPB005

Computational Model Analysis for Experimental Observation of Optical Current Noise Suppression Below the Shot-noise Limit

plasma, electron, linac, beam-transport

482

A. Gover
University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel
A. Nause
University of Tel Aviv, Tel Aviv, Israel

Funding: We acknowledge support of the Israel Science Foundation grant
We report first demonstration of optical frequency current shot-noise suppression in a relativistic e-beam. This process is made possible by collective Coulomb interaction between the electrons of a cold intense beam during beam drift, and is essentially a process of longitudinal beam-plasma oscillation.[1] Suppression of beam current noise below the classical “shot-noise” level has been known in the microwave tubes art [2]. This is the first time that it is demonstrated in the optical regime. We predict that the scheme can be extended to the XUV and possibly to shorter wavelengths with further development of technology. The fundamental current shot-noise determines the level of incoherent spontaneous radiation emission from electron-beam optical radiation sources and SASE-FELs [3]. Suppressing shot-noise would make it possible to attain spontaneous emission sub-radiance [4] and surpass the classical coherence limits of seed-injected FELs. The effect was demonstrated by measuring sub-linear growth as a function of current of the OTR Radiation. This finding indicates that the beam charge homogenizes due to the collective interaction, and its distribution becomes sub-Poissonian.
[1] A. Gover, E. Dyunin, PRL, 102, 154801, 2009
[2] H. Haus, N. Robinson, Proc. IRE, 43, 981 (1955)
[3] P. Emma, et al , Nature Photonics 4, 641 (2010)
[4] A. Dicke, Phys. Rev. 93, 99 (1954)

TUPB018

Study of Beam-Based Alignment for Shanghai Soft X-Ray FEL Facility

linac, emittance, alignment, FEL

513

D. Gu, Q. Gu, D. Huang, M. Zhang, M.H. Zhao
SINAP, Shanghai, People's Republic of China

In linear accelerators, dispersion caused by quadrupole misalignment and transverse wake-field effect caused by alignment errors of accelerate structures will lead to a significant emittance growth. There are more stringent restrictions on SXFEL, the traditional optical alignment can no longer meet its requirements, but the Beam-Based Alignment(BBA) method allows more precise alignment, further reduce the Linac errors to meet SXFEL requirements .In undulator sections, orbit changes are not only caused by misalignments of quadrupole magnet position ,but also the errors of undulator magnetic. In order to achieve alignment accuracy over longer distance, we measuring BPM data under different conditions and using SVD algorithm for calculation and analysis, we can get the quadrupole magnet errors and BPM offset. With the method above, software based on MATLAB has been designed and compared the results with other software.

TUPB023

The Optimization of RF Deflector Input Power Coupler

coupling, emittance, electron, diagnostics

528

A.Yu. Smirnov, O.A. Adonev, P.V. Binyukov, N.P. Sobenin
MEPhI, Moscow, Russia

This paper concerns the investigation of different types of input power cell for S-band RF electron deflector. This device serving for slice emittance diagnostics is a disc-loaded waveguide which operates with TE11-like wave in traveling wave regime with 120 deg phase shift per cell. Since this deflector meets the restriction on its length and has to provide high enough deflecting potential to a particle during its flight time it is significant to increase the transversal field strength in coupling cell or to shorten it so that the deflecting potential remains constant. The total structure consists of 14 regular cells and two couplers. As it is now all cells have the same length equal to D=33.34 mm and the field in couplers is lower than that of regular cells. In this paper different length are considered and numerically simulated in order to choose the best one.

TUPB031

Beam Envelope Analysis and Simulation

linac, ion, emittance, controls

543

V.S. Dyubkov, A.S. Plastun
MEPhI, Moscow, Russia

Forming the charge particle beams with small cross-sections and low energies is an actual problem for a linac design. That beams are used actively for isotope therapy, ion implantation, etc. Beam emittance is its quality factor, and it should be matched with a facility channel acceptance. The method for beam dynamics analysis at linac is developed in terms of non-coherent particle oscillation study. Nonlinear beam dynamics is investigated by using this method. It is shown that this technique allows one to realize effective beam emittance control. Analytical results obtained are verified by means of numerical simulation.

TUPB035

A New Design of the RFQ Channel for GSI HITRAP Facility

rfq, ion, DTL, linac

555

S.G. Yaramyshev, W.A. Barth, G. Clemente, L.A. Dahl, V. Gettmann, F. Herfurth, M. Kaiser, M.T. Maier, D. Neidherr, A. Orzhekhovskaya, H. Vormann, G. Vorobjev
GSI, Darmstadt, Germany
R. Repnow
MPI-K, Heidelberg, Germany

The HITRAP linac at GSI is designed to decelerate ions with mass to charge ratio of A/Z<3 from 4 MeV/u to 6 keV/u for experiments with ion traps. The particles are decelerated to 500 keV/u with an IH-DTL stucture and finally to 6 keV/u with a 4-rod RFQ. During commissioning stage the deceleration to approx. 500 keV/u was successfully demonstrated, while no particles behind the RFQ with an energy of 6 keV/u were observed. Dedicated simulations with DYNAMION code, based on 3D-fotometrie of the fabricated RFQ electrodes were successfully performed comprehending the commissioning results. In a second step the simulations have been experimentally confirmed at a test-stand (MPI, Heidelberg). An input energy, accepted by the RFQ channel is significantly higher than design value. For this reason the longitudinal beam emittance after deceleration with IH structure does not fit to the longitudinal RFQ acceptance. To solve this problem a new design of the RFQ channel with a correct input energy has been started. New RFQ parameters and the results of the beam dynamics simulations are presented in this paper.

TUPB036

Design of Re-Buncher Cavity for Heavy-ion LINAC in IMP

cavity, DTL, linac, impedance

558

L.P. Sun, X. Du, Y. He, A. Shi, C. Zhang, Z.L. Zhang
IMP, Lanzhou, People's Republic of China

A re-buncher with spiral arms for a heavy ion linear accelerator named as SSC-LNAC at HIRFL (the heavy ion research facility of Lanzhou) has been constructed. The re-buncher, which is used for beam longitudinal modulation and match between the RFQ and DTL, is designed to be operated in continuous wave (CW) mode at the Medium-Energy Beam-Transport (MEBT) line to maintain the beam intensity and quality. Because of the longitudinal space limitation, the re-buncher has to be very compact and will be built with four gaps. We determined the key parameters of the re-buncher cavity from the simulations using Microwave Studio software, such as the resonant frequency, the quality factor Q and the shunt impedance. The detailed design of a 53.667 MHz spiral cavity and measurement results of its prototype will be presented.

TUPB041

Scattering of H⁻ Stripped Electrons from SEM Grids and Wire Scanners at the CERN LINAC4

electron, scattering, linac, polarization

567

F. Roncarolo, E. Chevallay, M. Duraffourg, G.J. Focker, C. Heßler, U. Raich, VC. Vuitton, F. Zocca
CERN, Geneva, Switzerland
B. Cheymol
ESS, Lund, Sweden

At the CERN LINAC4, wire grids and scanners will be used to characterize the H⁻ beam transverse profile at different stages along the acceleration to 160 MeV. The wire signal will be determined by the balance between secondary emission and number of charges stopped in the wire, which will depend on the wire material and diameter, the possible choice of biasing (DC) the wires and the beam energy. The outermost electrons of H⁻ ions impinging on a wire are stripped in the first nanometers of material. A portion of such electrons are scattered away from the wire and can reach the neighboring wires. In addition, scattered electrons hitting the surrounding beam pipe generate secondary electrons that can also perturb the measurement. Monte Carlo simulations, analytical calculations and a laboratory experiment allowed quantifying the amount of scattering and the scattered particles distributions. The experiment was based on 70 keV electrons, well reproducing the case of 128 MeV H⁻ ions. For all the LINAC4 simulated cases the predicted effect on the beam size reconstruction results in a relative error of less than 5%.

TUPB048

Discussion of the Optimisation of a Linac Lattice to Minimise Disruption by a Class of Parasitic Modes

cavity, coupling, linac, lattice

585

S. Molloy
ESS, Lund, Sweden
R. Ainsworth
Royal Holloway, University of London, Surrey, United Kingdom

It is well known that each resonant mode in the RF spectrum of multi-cell accelerating cavities will split into a passband containing a number of modes, and that the coupling of these modes to the beam is dependent on the velocity of the accelerated particles. If these modes are found to degrade the quality of the beam, it is possible to take various measures to damp them, and thus keep their effect below some critical threshold. In the case of the parasitic modes within the same passband as the fundamental accelerating mode, their frequency is typically too close to that of the fundamental to allow their power to be safely extracted, and so cavity designers must rely on the natural damping of the cavity itself. This note contains a theoretical discussion of the coupling of the beam to these passband modes for a large class of accelerating cavities, and provides a mathematical model for use during the design and optimisation of linacs.

TUPB052

Studies of Parasitic Cavity Modes for Proposed ESS Linac Lattices

linac, cavity, proton, lattice

591

R. Ainsworth
Royal Holloway, University of London, Surrey, United Kingdom
S. Molloy
ESS, Lund, Sweden

The European Spallation Source (ESS) planned for construction in Lund, Sweden, will be the worlds most intense source of pulsed neutrons. The neutrons will be generated by the collision of a 2.5 GeV proton beam with a heavy-metal target. The superconducting section of the proton linac is split into three different types of cavities, and a question for the lattice designers is at which points in the beamline these splits should occur. This note studies various proposed designs for the ESS lattice from the point of view of the effect on the beam dynamics of the parasitic cavity modes lying close in frequency to the fundamental accelerating mode. Each linac design is characterised by the initial kinetic energy of the beam, as well as by the velocity of the beam at each of the points at which the cavity style changes. The scale of the phase-space disruption of the proton pulse is discussed, and some general conclusions for lattice designers are stated.

TUPB055

R&D of IMP Superconducting HWR for China ADS

cavity, niobium, linac, proton

600

W.M. Yue, X.L. Guo, S. He, Y. He, R.X. Wang, P.R. Xiong, M.X. Xu, B. Zhang, C. Zhang, S.H. Zhang, S.X. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

The R&D program of IMP superconducting HWR is based on the China ADS, The aim is to build and test a HWR prototype on December 2012. We have designed a 162.5 MHz β=0.09 half-wave resonator (HWR), and a copper HWR has been fabricated in January 2012. The fabrication of a Nb HWR will be completed by September 2012, and the fabrication of a slow tuner and a high power coupler for this HWR will be completed then. In this poster, we present the HWR electromagnetic design, mechanical design, fabrication arts, copper HWR RF test result, the design of the slow tuner and the power coupler.

TUPB056

The Multipacting Simulation for the New-shaped QWR using TRACK3P

cavity, accelerating-gradient, electron, niobium

603

C. Zhang, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, S.H. Zhang, S.X. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

In order to improve the electro-magnetic performance of the quarter wave resonator, a new-shaped cavity with an elliptical cylinder outer conductor has been proposed. This novel cavity design can provide much lower peak surface magnetic field and much higher Ra/Q0 and G. The Multipacting simulation has been done for this new QWR cavity using ACE3P/TRACK3P code, in this paper the simulation results will be presented and analyzed.

TUPB057

Structural Analysis of the New-Shaped QWR for HIAF in IMP

cavity, superconducting-cavity, SRF, controls

606

C. Zhang, S. He, Y. He, S.C. Huang, Y.L. Huang, T.C. Jiang, R.X. Wang, M.X. Xu, Y.Z. Yang, W.M. Yue, S.H. Zhang, S.X. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

Since the QWR cavity is very successful for the operation with frequency of 48 to 160 MHz and \beta value of 0.001 to 0.2, a new-shaped QWR is being designed for the low energy superconducting section of HIAF in the Institute of Modern Physics. The cavity will work at 81.25 MHz and \beta of 0.085，with a elliptical cylinder outer conductor to better its electro-magnetic performance and keep limited accelerating space. Structural design is an important aspect of the overall cavity implementation, and in order to minimize the frequency shift of the cavity due to the helium bath pressure fluctuations, the Lorentz force and microphonic excitation, stiffening elements have to be applied. In this paper, structural analyses of the new-shaped QWR are presented and stiffening methods are explored.

TUPB058

An Analytical Cavity Model for Fast Linac-Beam Tuning

multipole, quadrupole, cavity, dipole

609

Z.Q. He, Z. Zheng
TUB, Beijing, People's Republic of China
Z.Q. He, Z. Liu, J. Wei, Y. Zhang
FRIB, East Lansing, Michigan, USA

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
Non-axisymmetric RF cavities can produce axially asymmetric acceleration fields. Conventional method using numerical 3-D field tracking to address this feature is time-consuming and thus not appropriate for on-line beam tuning applications. In this paper, we develop analytical treatment of non-axisymmetric RF cavities. Multipole models of cavities are derived using realistic 3-D field in both longitudinal and transverse dimensions. Then, beam dynamics formulism is established. Finally, special case of FRIB quarter-wave resonators are calculated by the model and benchmarked against 3-D field tracking to ensure the efficiency and accuracy of the model.

TUPB060

Multipacting Suppression Modeling for Half Wave Resonator and RF Coupler*

cavity, electron, cryomodule, impedance

612

Z. Zheng, A. Facco, Z. Liu, J. Popielarski, K. Saito, J. Wei, Y. Xu, Y. Zhang
FRIB, East Lansing, Michigan, USA
Z. Zheng
TUB, Beijing, People's Republic of China

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
In prototype cryomodule test of Facility of Rare Isotope Beam (FRIB) β=0.53 half-wave-resonators (HWRs) severe multipacting barriers, prevented RF measurement at the full field specified. The multipacting could not be removed by several hours of RF conditioning. To better understand and to eliminate multipacting, physics models and CST simulations have been developed for both cavity and RF coupler. The simulations have good agreement with the multipacting discovered in coupler and cavity testing. Proposed cavity and coupler geometric optimizations are discussed in this paper.

TUPB061

ADRC Control for Beam Loading and Microphonics

controls, cavity, beam-loading, LLRF

615

Z. Zheng, Z. Liu, J. Wei, Y. Zhang, S. Zhao
FRIB, East Lansing, Michigan, USA
Z. Zheng
TUB, Beijing, People's Republic of China

Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
Superconducting RF (SRF) cavities are subject to many disturbances such as beam loading and microphonics. Although we implemented Proportional Integral (PI) control and Active Disturbance Rejection Control (ADRC) in the Low Level RF (LLRF) system at FRIB to stabilize the RF field, the control loop gains are inadequate in the presence of beam loading and microphonics. An improved scheme is proposed and simulated with much higher gains are achieved. The feasibility to include piezo tuner in ADRC and PI circuit is also presented in this paper.

TUPB067

Development of a Superconducting Half-Wave Resonator for PXIE

cavity, linac, cryomodule, niobium

624

Z.A. Conway, R.L. Fischer, S.M. Gerbick, M. Kedzie, M.P. Kelly, S.V. Kutsaev, B. Mustapha, P.N. Ostroumov, K.W. Shepard
ANL, Argonne, USA
I.V. Gonin, A. Lunin, V.P. Yakovlev
Fermilab, Batavia, USA

Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics and Nuclear Physics, under contract DE-AC02-76CH03000 and DE-AC02-06CH11357
An ambitious upgrade to the FNAL accelerator complex is progressing in the Project-X Injector Experiment (PXIE). The PXIE accelerator requires 8 superconducting half-wave resonators optimized for the acceleration of 1 mA β = 0.11 H⁻ ion beams. Here we present the status of the half-wave resonator development, focusing particularly on cavity design, with a brief update on prototype fabrication.

TUPB069

BEAMDULAC-SCL Code for Complex Approach of Beam Dynamic Investigation in SC LINAC

ion, linac, focusing, solenoid

630

A.V. Samoshin
MEPhI, Moscow, Russia

Periodic sequences of independently phased accelerating cavities and focusing solenoids are used in MeV and GeV energy range linacs. The beam dynamic investigation is difficult for such superconducting linear accelerator. The matrix calculation was preferably used for primary choused of accelerating structure parameters. This method does not allows properly investigate the longitudinal motion. The smooth approximation can be used to investigate the nonlinear ion beam dynamics in such accelerating structure and to calculate longitudinal and transverse acceptances. The potential function and the equation of motion in the Hamilton form are devised by the smooth approximation. The advantages and disadvantages of each method will describe, the results of investigation will compare. The user friendly software BEAMDULAC-SCL for ion beam dynamic analysis was created. A numerical simulation of beam dynamics in the real field are carried out for the different variants of the accelerator structure based on previously analytically obtained results.

TUPB071

First Measurements on the 325 MHz Superconducting CH Cavity

cavity, controls, linac, coupling

636

M. Busch, F.D. Dziuba, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany
M. Amberg
HIM, Mainz, Germany
W.A. Barth, S. Mickat
GSI, Darmstadt, Germany
M. Pekeler
RI Research Instruments GmbH, Bergisch Gladbach, Germany

Funding: Work supported by GSI, BMBF Contr. No. 06FY7102, 06FY9089I
At the Institute for Applied Physics (IAP), Frankfurt University, a superconducting 325 MHz CH-Cavity has been designed and built. This 7-cell cavity has a geometrical \beta of 0.16 corresponding to a beam energy of 11.4 AMeV. The design gradient is 5 MV/m. Novel features of this resonator are a compact design, low peak fields, easy surface processing and power coupling. Furthermore a new tuning system based on bellow tuners inside the resonator will control the frequency during operation. After successful rf tests in Frankfurt the cavity will be tested with a 10 mA, 11.4 AMeV beam delivered by the GSI UNILAC. In this paper first measurements and corresponding simulations will be presented.

TUPB072

Status of the Superconducting CW Demonstrator for GSI

cavity, linac, solenoid, cryogenics

639

F.D. Dziuba, M. Amberg, M. Busch, H. Podlech, U. Ratzinger
IAP, Frankfurt am Main, Germany
K. Aulenbacher
IKP, Mainz, Germany
W.A. Barth, S. Mickat
GSI, Darmstadt, Germany

Funding: Helmholtz Institut Mainz (HIM), GSI, BMBF Contr. No. 06FY7102
Since the existing UNILAC at GSI will be used as an injector for the FAIR facility a new superconducting (sc) continous wave (cw) LINAC is highly requested by a broad community of future users to fulfil the requirements of nuclear chemistry, especially in the research field of Super Heavy Elements (SHE). This LINAC is under design in collaboration with the Institute for Applied Physics (IAP) of Frankfurt University, GSI and the Helmholtz Institut Mainz (HIM). It will consist of 9 sc Crossbar-H-mode (CH) cavities operated at 217 MHz which provide an energy up to 7.3 AMeV. Currently, a prototype of the cw LINAC is under development. This demonstrator comprises the first sc CH cavity of the LINAC embedded between two sc solenoids mounted in a horizontal cryomodule. One important milestone of the project will be a full performance test of the demonstrator by injecting and accelerating a beam from the GSI High Charge State Injector (HLI) in 2014. The status of the demonstrator is presented.

TUPB073

Design and Simulation of a Test Model for a Tri-Spoke Cavity at RIKEN

cavity, vacuum, superconducting-cavity, electron

642

L. Lu
RIKEN, Saitama, Japan
O. Kamigaito, N. Sakamoto, K. Suda, K. Yamada
RIKEN Nishina Center, Wako, Japan

A design for a tri-spoke-type superconducting cavity for uranium beams with β = 0.303 and a 219 MHz operational frequency is presented. And a test model designed and assembled by two end-wall flanges and one triparted part of the designed tri-spoke cavity, was expected to be built using the same fabrication technology that is supposed for Nb cavity manufacture. The designs and simulations of the tri-spoke cavity and the test model will be reported in this paper.

TUPB082

Beam Loss Track Measurements by a Fast Trigger Scheme in J-PARC Linac

linac, background, proton, neutron

663

H. Sako, T. Maruta, A. Miura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

Funding: Work partially supported by Grant-in-Aid for Challenging Exploratory Research
In J-PARC Linac, highest beam loss has been observed at the ACS (Annular-Coupled Structure linac) section. The primary source of the beam loss is considered to be H⁰ produced by an interaction of H⁻ beams with remnant gas. The H⁰ hits the beam duct, converted to H⁺, and escapes from the beam duct. To detect the H⁺'s and estimate the absolute magnitude of the beam loss, we constructed a detector system, which consists of 6 planes of hodoscopes made of 16 scintillation fibers with 64 x 64 mm² area. The scintillation light is measured by multi-anode photomultipliers. In the ACS section, two planes to measure horizontal positions are installed, and at about 1 m downstream positions, two planes for horizontal measurements and two for vertical measurements are placed. We will reconstruct charged particles passing through all the 6 planes, and measure the velocity by time-of-flight and energy loss to identify particle species. We present new measurements since the recovery of the J-PARC after the earthquake started in April 2012 by a new fast trigger scheme using dynode signals of photomultipliers in order to improve signal-to-noise ratios.

TUPB090

Development of Permanent Magnet Focusing System for Klystrons

klystron, focusing, permanent-magnet, cathode

669

Y. Fuwa, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
S. Fukuda, S. Michizono
KEK, Ibaraki, Japan

A permanent magnet focusing system for klystrons is under development to improve reliability of RF supply system and reduce power consumption. To save production cost, anisotropic ferrite magnets are used in this system. A test model has been fabricated and the power test of a 750 kW klystron with this focusing magnet is carried out. 60 % of the nominal output power has been achieved at a preliminary power test so far

TUPB091

176 MHz Solid State Microwave Generator Design

impedance, linac, scattering, resonance

672

A.Yu. Smirnov, E.V. Ivanov, A.A. Krasnov, K.I. Nikolskiy, N.V. Tikhomirova
Siemens Research Center, Moscow,, Russia
O. Heid, T.J.S. Hughes
Siemens AG, Erlangen, Germany

This paper concerns the R&D work upon design of a compact RF amplifier to be used for superconducting CW cavities. The machine under development will operate at 176 MHz with output power of 25 kW in continuous wave regime. It consists of 50 push-pull PCB modules (approx. 500W output power each), connected in parallel to several radial filter rings, which both allow class-F operation and combine the power from the modules, delivering it to a single 50 Ω coax cable. The CST simulations ad the design of 324 MHz test prototype are presented.

TUPB093

Compact 4 kW Variable RF Power Coupler for FRIB Quarter-wave Cavities

cavity, cryomodule, vacuum, linac

678

M.P. Kelly, Z.A. Conway, M. Kedzie, S.V. Kutsaev
ANL, Argonne, USA
J.L. Crisp, L.L. Harle
FRIB, East Lansing, Michigan, USA

A new compact 4 kW power coupler has been designed and prototyped at Argonne National Laboratory in collaboration with Michigan State University. The coupler is intended for use on the β=0.085 80.5 MHz superconducting quarter-wave cavities for the FRIB driver linac and also for the planned ReA6 quarter-wave cavity cryomodule. The design has a cold RF window and a 3 cm variable bellows section. The 16 cm overall length of the RF window and bellows facilitates a simple and compact installation onto the cavity inside the clean room. A prototype have been cold tested with high power under realistic conditions at Argonne and results are presented.

TUPB094

High Power Tests of TRASCO RFQ Couplers

vacuum, cavity, rfq, klystron

681

E. Fagotti, L. Antoniazzi, F. Grespan, A. Palmieri, F. Scarpa
INFN/LNL, Legnaro (PD), Italy
O. Brunasso Cattarello, R. Panero
INFN-Torino, Torino, Italy
M. Desmons
CEA/DSM/IRFU, France

The 352.2 MHz 7.13 m long TRASCO RFQ requires an overall amount of 900 kW CW RF power in order to deliver the 40 mA proton beam from the initial energy of 80 keV to the final energy of 5 MeV. For such a purpose a system of eight compact (ϕext=38 mm, ϕint=19.4 mm) loop-based couplers was designed. In a first phase, only the first two (out of six) modules of the RFQ were tested at full power. Therefore only two (out of eight) couplers were used. In order to completely characterize these couplers, a dedicated test bench was prepared, consisting of a bridge waveguide and diagnostics (reflected power, vacuum, arc detectors etc.), onto which a couple of couplers was connected for transmission measurements. Each coupler was tested with a forward power of up to 140 kW. The description of the experimental setup and procedure, as well as the main results of the conditioning procedure will be reported in this paper.

TUPB097

The C-band RF Pulse Compression for Soft XFEL at SINAP

cavity, coupling, klystron, free-electron-laser

687

C.P. Wang, Q. Gu, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

A compact soft X-ray free electron laser facility is presently being constructed at shanghai institute of applied physics (SINAP), Chinese academy of science in 2012 and will be accomplished in 2014. This facility requires a compact linac with a high-gradient accelerating structure for a limited overall length less than 230 m. The c-band technology which is already used in KEK/Spring-8 linear accelerator is a good compromise for this compact facility and a c-and traveling-wave accelerating structure was already fabricated and tested at SINAP, so a c-band pulse compression will be required. AND a SLED type RF compression scheme is proposed for the C-band RF system of the soft XFEL and this scheme uses TE0.1.15 mode energy storage cavity for high Q-energy storage. The C-band pulse compression under development at SINAP has a high power gain about 3.1 and it is designed to compress the pulse width from 2.5 μs to 0.5 μs and multiply the input RF power of 50 MW to generate 160 MW peak RF power, and the coupling coefficient will be 8.5. It has three components: 3 dB coupler, mode convertors and the resonant cavities.

TUPB107

Amplitude and Phase Control of the Accelerating Field in the ESS Spoke Cavity

cavity, controls, feedback, beam-loading

708

V.A. Goryashko, R.J.M.Y. Ruber, R.A. Yogi, V.G. Ziemann
Uppsala University, Uppsala, Sweden

We report about numerical simulations of the accelerating field dynamics in the ESS spoke cavity in the presence of the beam loading and Lorentz detuning. A slow feedforward is used to cure the Lorentz detuning whereas a fast feedback through a signal oscillator and cavity pre-detuning technique are applied to eliminate the beam loading effect. An analysis performed with a Simulink model shows that a combination of feedforward, feedback and cavity pre-detuning result in a substantially shorter stabilization time of the field voltage and phase on a required level as compared to a control method using only the feedforward and feedback. The latter allows one to obtain smaller magnitude but longer duration of deviations of the instantaneous voltage and phase from the required nominal values. As a result, a series of cavities only with feedforward and feedback needs an extra control technique to mitigate a cumulative systematic error rising in each cavity. In addition, a technique of adiabatic turning off of the RF power in order to prevent a high reflected power in the case of a sudden beam loss is studied.

TH2A004

Computational Model Analysis for Experimental Observation of Optical Current Noise Suppression Below the Shot-noise Limit

plasma, electron, linac, beam-transport

783

A. Gover
University of Tel-Aviv, Faculty of Engineering, Tel-Aviv, Israel
A. Nause
University of Tel Aviv, Tel Aviv, Israel

Funding: We acknowledge support of the Israel Science Foundation grant
We report first demonstration of optical frequency current shot-noise suppression in a relativistic e-beam. This process is made possible by collective Coulomb interaction between the electrons of a cold intense beam during beam drift, and is essentially a process of longitudinal beam-plasma oscillation.[1] Suppression of beam current noise below the classical “shot-noise” level has been known in the microwave tubes art [2]. This is the first time that it is demonstrated in the optical regime. We predict that the scheme can be extended to the XUV and possibly to shorter wavelengths with further development of technology. The fundamental current shot-noise determines the level of incoherent spontaneous radiation emission from electron-beam optical radiation sources and SASE-FELs [3]. Suppressing shot-noise would make it possible to attain spontaneous emission sub-radiance [4] and surpass the classical coherence limits of seed-injected FELs. The effect was demonstrated by measuring sub-linear growth as a function of current of the OTR Radiation. This finding indicates that the beam charge homogenizes due to the collective interaction, and its distribution becomes sub-Poissonian.
[1] A. Gover, E. Dyunin, PRL, 102, 154801, 2009
[2] H. Haus, N. Robinson, Proc. IRE, 43, 981 (1955)
[3] P. Emma, et al , Nature Photonics 4, 641 (2010)
[4] A. Dicke, Phys. Rev. 93, 99 (1954)

THPLB03

Front-End Linac Design and Beam Dynamics Simulations for MYRRHA

rfq, DTL, emittance, linac

813

C. Zhang, H. Klein, D. Mäder, H. Podlech, U. Ratzinger, A. Schempp, R. Tiede, M. Vossberg
IAP, Frankfurt am Main, Germany

Funding: Funded by the European Atomic Energy Community’s (Euratom) 7th Framework Programme under Grant Agreement n°269565.
A 17MeV, 176MHz, and CW (Continuous Wave) proton linac is being developed as the front end of the driver accelerator for the MYRRHA facility in Mol, Belgium. Based on the promising preliminary design, further simulation and optimization studies have been performed with respect to code benchmarking, RFQ simulation using realistic LEBT output distributions, and an updated CH-DTL design with more detailed inter-tank configurations. This paper summarizes the new results.

Slides THPLB03 [1.292 MB]

THPLB11

Experimental and Simulation Study of the Long-path-length Dynamics of a Space-charge-dominated Bunch

space-charge, electron, emittance, focusing

834

I. Haber, B.L. Beaudoin, S. Bernal, R.A. Kishek, T.W. Koeth, Y. Mo
UMD, College Park, Maryland, USA

Funding: Work supported by the United States Department of Energy and the Office of Naval Research.
The University of Maryland Electron Ring (UMER) is a low-energy (10 keV) electron facility built to study, on a scaled machine, the long-propagation-length evolution of a space-charge-dominated beam. Though constructed in a ring geometry to achieve a long path length at modest cost, UMER has observed important space-charge physics directly relevant to linear machines. Examples will be presented that emphasize studies of the longitudinal dynamics and comparisons to axisymmetric simulations. The detailed agreement obtained between simulation and experiment will be presented as evidence that the longitudinal physics observed is not strongly influenced by the ring geometry. Novel phenomena such as soliton formation, unimpeded bunch-end interpenetration, and an instability that occurs after this interpenetration, will be discussed.

THPB004

Current Status of the RAL Front End Test Stand (FETS) Project

rfq, ion, ion-source, diagnostics

846

D.C. Plostinar, C. Gabor
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
S.M.H. Alsari, M. Aslaninejad, A. Kurup, J.K. Pozimski, P. Savage
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
J.J. Back
University of Warwick, Coventry, United Kingdom
G.E. Boorman, A. Bosco
Royal Holloway, University of London, Surrey, United Kingdom
M.A. Clarke-Gayther, D.C. Faircloth, S.R. Lawrie, A.P. Letchford
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
S. Jolly
UCL, London, United Kingdom

The UK proton accelerator strategy aims to develop a viable high power proton driver with applications including spallation neutrons, the neutrino factory and ADSR. An essential first ingredient, identified as one of the main UK R&D accelerator projects, is the Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL), aimed at producing a high quality, high current, cleanly chopped H⁻ beam. Through its component parts, FETS has triggered development of a high brightness, 60 mA H⁻ ion source, a three-solenoid Low Energy Beam Transport line (LEBT), a 3 MeV four-vane Radio-Frequency Quadrupole (RFQ) and a Medium Energy Beam Transport line (MEBT) with a high speed chopper. The project is well advanced and when operational should be sufficiently versatile to explore a range of operating conditions. In this paper we present the current status of the construction, and plans for operation, experiments and future development.

THPB005

Front-End Linac Design and Beam Dynamics Simulations for MYRRHA

rfq, DTL, emittance, linac

849

C. Zhang, H. Klein, D. Mäder, H. Podlech, U. Ratzinger, A. Schempp, R. Tiede, M. Vossberg
IAP, Frankfurt am Main, Germany

Funding: Funded by the European Atomic Energy Community’s (Euratom) 7th Framework Programme under Grant Agreement n°269565.
A 17MeV, 176MHz, and CW (Continuous Wave) proton linac is being developed as the front end of the driver accelerator for the MYRRHA facility in Mol, Belgium. Based on the promising preliminary design, further simulation and optimization studies have been performed with respect to code benchmarking, RFQ simulation using realistic LEBT output distributions, and an updated CH-DTL design with more detailed inter-tank configurations. This paper summarizes the new results.

THPB007

A Pulsed Linac Front-end for ADS Applications

proton, rfq, emittance, linac

855

U. Ratzinger, H. Podlech, A. Schempp, K. Volk
IAP, Frankfurt am Main, Germany
U. Hagen, O. Heid, T.J.S. Hughes
Siemens AG, Erlangen, Germany
H. Hoeltermann
BEVATECH OHG, Offenbach/Main, Germany

Quite a number of projects worldwide develop proton driver linacs for neutron sources and other accelerator driven systems. One trend is to use a high duty factor and superconducting cavities as much as possible. Alternatively, one can aim on short duty factor and count on a continuing rapid development of pulsed rf amplifiers based on power transistor technology. A 500 mA, 5 % duty factor layout of a proton injector is presented, consisting of a filament driven volume ion source, of a 150 keV transport section and of a 4 m long 162 MHz RFQ up to 2 MeV beam energy. Beam dynamics results as well as the technical design will be shown.

THPB008

A Coupled RFQ-IH Cavity for the Neutron Source FRANZ

rfq, cavity, DTL, coupling

858

M. Heilmann, O. Meusel, D. Mäder, U. Ratzinger, A. Schempp, M. Schwarz
IAP, Frankfurt am Main, Germany

The Frankfurt neutron source FRANZ will deliver neutrons in the energy range from 1 to 500 keV with high pulsed intensities. A 2 MeV proton beam will produce protons via the 7Li(p,n)7Be reaction. The 175 MHz accelerator cavity consists of a 4-rod-RFQ coupled with an 8 gap interdigital H-type drift tube section, the total cavity length being 2.3m. The combined cavity will be powered by one RF amplifier to reduce investment and operation costs. The inductive power coupler will be at the RFQ part. The coupling into the IH - section is provided through a large aperture - mainly inductively. By CST - MWS - simulations as well as by an RF - model the voltage tuning along the cavity was investigated, and with special care the balance between both cavity sections. A first set of RFQ electrodes should allow to reach beam currents up to 50 mA in cw operation: The beam is pulsed with 100 ns, 250 kHz, while the cavity has to be operated cw due to the high rep. rate. The layout of the cavity cooling aims on a maximum accessible heat load of 200 kW.

THPB011

Linac4 45 keV Proton Beam Measurements

rfq, solenoid, linac, proton

867

G. Bellodi, V.A. Dimov, L.M. Hein, J.-B. Lallement, A.M. Lombardi, O. Midttun, R. Scrivens
CERN, Geneva, Switzerland
P.A. Posocco
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

Linac4 is a 160 MeV normal-conducting H⁻ linear accelerator, which will replace the 50 MeV proton Linac (Linac2) as injector for the CERN proton complex. Commissioning of the low energy part - H⁻ source, a 45 keV Low Energy Beam Transport line (LEBT), a 3 MeV RFQ and a Medium Energy Beam Transport (MEBT) line - will start in fall 2012 on a dedicated test stand installation. In preparation to this, preliminary measurements were taken in the past few months using a 45 keV proton source and a temporary LEBT setup, with the aim of characterising the output beam by comparison with simulations. This also allowed a first verification of the diagnostics instrumentation and acquisition software tools. Measurements of beam profile, emittance and intensity were taken after the source, after the first and after the second LEBT solenoids respectively. Particle distributions were reconstructed from emittance scans and used as input to simulation studies of the beam transport through the line. Comparison of the results with the measurements allowed an experimental validation of the LEBT (in terms of misalignments and calibration points) and qualification of the beam at the source output.

THPB022

Beam Phase Measurement for PEFP Linear Accelerator

linac, DTL, LLRF, proton

894

H.S. Kim, Y.-S. Cho, J.-H. Jang, H.-J. Kwon, J.Y. Ryu, K.T. Seol, Y.-G. Song
KAERI, Daejon, Republic of Korea

Funding: Works supported by the Ministry of Education, Science and Technology of Korean Government.
According to the commissioning plan of the PEFP proton linac, an accurate measurement of beam phase is essential, especially for setting up the RF operating parameters of DTL. Beam position monitors (BPMs) installed between DTL tanks can provide information about the beam phase as well as about the beam transverse position. By using a BPM as a beam phase monitor, beam phase can be measured without additional devices on the linac or the beam line. The signals from 4 electrodes in the BPM can be summed by using a 4-way RF combiner, by which the effect of the transverse beam offset on the phase measurement can be eliminated. The combined BPM signal (350 MHz) is mixed with LO signal (300 MHz) and down-converted to IF signal (50 MHz), then fed into the signal processing unit, where the phase information is extracted by using IQ demodulation method with a sampling frequency of 40 MHz. In this paper, the beam phase measurement system and signal processing scheme will be presented.

THPB026

The Beam Commissioning Plan of Injector II in C-ADS

rfq, cavity, proton, diagnostics

906

Z.J. Wang, Y. He, H. Jia, C. Li, S.H. Liu, W. Wu, X.B. Xu, B. Zhang, H.W. Zhao
IMP, Lanzhou, People's Republic of China

The design work of the Injector II, which is 10 MeV proton linac, in C-ADS project is being finished and some key elements are being fabricated. Now it is necessary to definite the operation mode of beam commissioning, including the selection of the beam current, pulse length and repetition frequency. Also the beam commissions plan should be specified. The beam commissions procedures is simulated with t-mode code GPT. In this paper, the general beam commissioning plan of Injector II in CIADS and simulation results of commissions procedures are presented.

THPB030

DTL Design for ESS

DTL, linac, proton, drift-tube-linac

918

M. Comunian, F. Grespan, A. Pisent
INFN/LNL, Legnaro (PD), Italy
R. De Prisco
Lund University, Lund, Sweden
M. Eshraqi
ESS, Lund, Sweden
P. Mereu
INFN-Torino, Torino, Italy

In the present design of the European Spallation Source (ESS) accelerator, the Drift Tube Linac (DTL) will accelerate a proton beam of 50 mA pulse peak current from 3 to 80 MeV. It is designed to operate at 352.2 MHz, with a duty cycle of 4% (3 ms pulse length, 14 Hz repetition period). Permanent magnet quadrupoles (PMQs) are used as focusing elements in a FODO lattice scheme, which leaves space for steerers and diagnostics . In this paper beam dynamics studies and preliminary RF design are shown, including constraints in terms of quadrupole dimensions, total length, field stability, RF power, peak electric field.

THPB046

RF Setup of the MedAustron RFQ

rfq, resonance, ion, pick-up

957

B. Koubek, A. Schempp, J.S. Schmidt
IAP, Frankfurt am Main, Germany
J. Haeuser
Kress GmbH, Biebergemuend, Germany

A Radio Frequency Quadrupole (RFQ) was built for the injector of the cancer treatment facility MedAuston in Austria. For the RF design simulations were performed using CST Microwave Studio and the structure was manufactured by Firma Kress in Biebergemuend, Germany. The simulations and the RF setup of the delivered RFQ are presented in this paper.

THPB047

Test RFQ for the MAX Project

rfq, cavity, linac, proton

960

M. Vossberg, H. Klein, H. Podlech, A. Schempp, C. Zhang
IAP, Frankfurt am Main, Germany
A. Bechtold
NTG Neue Technologien GmbH & Co KG, Gelnhausen, Germany

As a part of the MAX project it will be demonstrated by simulations and thermal measurements, that a 4-rod-RFQ is the right choice even at cw-operation. A 4-rod Test-RFQ with a resonance frequency of 175 MHz has been designed and built for the MAX-Project. But the RFQ had to be modified to solve the cooling problem at cw-operation, the geometrical precision had to be improved as well as the rf-contacts. The developments led to a new layout and a sophisticated production procedure of the stems and the electrodes. Calculations show an improved Rp-value leading to powerlosses of ca. 25 kW/m only, which is about half of the powerlosses which could be achieved safely at cw-operation of the similar Saraf-RFQ. Thermal measurements and simulations with the single components are in progress. The temperature distribution in cw-operation will be measured and the rf-performance checked.

THPB049

Tuning Studies on 4-Rod-RFQs

rfq, linac, resonance, coupling

963

J.S. Schmidt, B. Klump, B. Koubek, A. Schempp
IAP, Frankfurt am Main, Germany

A NI LabVIEW based Tuning Software has been devel- oped to structure the tuning process of 4-rod Radio Fre- quency Quadrupole s (RFQs). Its results are compared to measurement data of 4-rod RFQs in different frequency ranges. For the optimization of RFQ design parameters, a certain voltage distribution along the electrodes of an RFQ is assumed. Therefore an accurate tuning of the voltage distribution is very important for the beam dynamic prop- erties of an RFQ. A variation can lead to particle losses and reduced beam quality especially at higher frequencies. Our electrode design usually implies a constant longitudi- nal voltage distribution. For its adjustment tuning plates are used between the stems of the 4-rod-RFQ. These pre- dictions are based, in contrast to other simulations, on mea- surements to define the characteristics of the RFQ as it was build - not depending on assumptions of the design. This will lead to a totally new structured process of tuning 4- rod-RFQs in a broad range of frequencies by using the pre- dictions of a software. The results of these studies are pre- sented in this paper.

THPB050

RFQ With Improved Energy Gain

rfq, acceleration, ion, emittance

966

A. Kolomiets
ITEP, Moscow, Russia
A.S. Plastun
MEPhI, Moscow, Russia

RFQ structure is practically only one choice for using in front ends of ion linacs for acceleration up to energy about 3 MeV. This limit is due to its relatively low acceleration efficiency. However it isn’t intrinsic feature of RFQ principle. It is defined only by vane geometry of conventional RFQ structure with sinusoidal modulation of vanes. The paper presents results of analysis RFQ with modified vane geometries that allow to improve acceleration efficiency. RFQ with modified vanes was used for design second section of heavy ion injector of TWAC for acceleration of ions with Z/A = 0.33 up to 7 MeV/u.

THPB052

Recent Progress with the J-PARC RFQs

rfq, linac, emittance, vacuum

972

Y. Kondo, K. Hasegawa, T. Morishita
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
H. Kawamata, F. Naito, T. Sugimura
KEK, Ibaraki, Japan

In this paper, we will report recent topics about J-PARC RFQs. First, the operating RFQ (RFQ I) have been recovered from the long shutdown due to the earthquake. This RFQ have been suffered from breakdown problem since 2008, therefore we have been developing a back-up RFQ (RFQ II). In April 2012, the high power test was successfully performed. Finally, we are fabricating a new RFQ for the beam-current upgrade of the J-PARC linac (RFQ III). The status of these RFQs are described.

THPB055

Numerical Simulations of ProjectX/PXIE RFQ

rfq, linac, emittance, space-charge

975

J.-F. Ostiguy, A. Saini, N. Solyak
Fermilab, Batavia, USA

Funding: Fermi Research Alliance, LLC under DOE Contract No. De-AC02-07CH11359
Project-X is a proposed superconducting linac-based high intensity proton source at Fermilab. The machine first stages operate in CW mode from 2.1 to 3 GeV and a high bandwidth chopper is used to produce the required bunch patterns. A 162.5 MHz CW RFQ accelerates the beam from 30 keV to 2.1 MeV. A concern with CW operation is that losses either within the RFQ or in the dowstream modules should be well-understood and remain very low to ensure safe and/or reliable operation. In this contribution, we investigate the suitability of existing RFQ codes and model the PXIE RFQ (ProjectX test facility) designed constructed by LBNL to make useful predictions of loss patterns and phase space distribution.

THPB061

Experimental and Simulation Study of the Long-path-length Dynamics of a Space-charge-dominated Bunch

space-charge, electron, emittance, focusing

978

I. Haber, B.L. Beaudoin, S. Bernal, R.A. Kishek, T.W. Koeth, Y. Mo
UMD, College Park, Maryland, USA

Funding: Work supported by the United States Department of Energy and the Office of Naval Research.
The University of Maryland Electron Ring (UMER) is a low-energy (10 keV) electron facility built to study, on a scaled machine, the long-propagation-length evolution of a space-charge-dominated beam. Though constructed in a ring geometry to achieve a long path length at modest cost, UMER has observed important space-charge physics directly relevant to linear machines. Examples will be presented that emphasize studies of the longitudinal dynamics and comparisons to axisymmetric simulations. The detailed agreement obtained between simulation and experiment will be presented as evidence that the longitudinal physics observed is not strongly influenced by the ring geometry. Novel phenomena such as soliton formation, unimpeded bunch-end interpenetration, and an instability that occurs after this interpenetration, will be discussed.

THPB063

Simulated Performance of the CARIBU EBIS Charge Breeder Transport Line

ion, emittance, diagnostics, electron

984

C. Dickerson, S.A. Kondrashev, B. Mustapha, P.N. Ostroumov
ANL, Argonne, USA

Funding: This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under contract number DE-AC02-06CH11357.
An Electron Beam Ion Source (EBIS) has been designed and is being built to charge breed ions from the CAlifornium Rare Isotope Breeder Upgrade (CARIBU) for post acceleration in the Argonne Tandem Linear Accelerator System (ATLAS). The calculated transverse acceptance of the EBIS charge breeder can approach the emittance of the injected ion beam, so beam distortion during transport could lead to incomplete injection and a decrease in the overall system efficiency. The beam quality can be maintained for simulations of the transport line using the ideal ion beam parameters. This paper reports the results of the electrostatic and ion beam transport simulations used to minimize the ion beam distortions by optimizing component designs and configurations.

THPB064

Beam Dynamics Tools for Linacs Design

electron, beam-loading, linac, synchrotron

987

A.S. Setty
THALES, Colombes, France

In the last 25 years, we have been using our in house 3D code PRODYN * for electron beam simulations. We have also been using our in house code SECTION for the design of the travelling wave accelerating structures and the beam loading compensation. PRODYN follows in time, the most complicated electron trajectories with relativistic space-charge effects. This code includes backward as well as forwards movements. This paper will describe those two codes and will give some simulations and measurements results.
* D. Tronc and A. Setty, Electrons RF auto-focusing and capture in bunchers, Linear Accelerator Conference 1988, Virginia.

THPB065

Status of the Beam Dynamics Code DYNAC

dipole, rfq, emittance, quadrupole

990

E. Tanke, J.A. Rodriguez, W. Wittmer, X. Wu
FRIB, East Lansing, Michigan, USA
S. Valero
CEA, Gif-sur-Yvette, France
D. Wang
NSCL, East Lansing, Michigan, USA

Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
The beam dynamics code DYNAC* was originally developed at CERN. For accelerating elements a set of very accurate quasi-Liouvillian beam dynamics equations was introduced, applicable to protons, heavy ions and non-relativistic electrons. Furthermore, DYNAC contains three space charge routines, including a 3D version**. More recently, a numerical method has been added, capable of simulating a multi charge state ion beam in accelerating elements (i.e. cavities). Beam line devices such as sextupoles and quadrupole-sextupole magnets as well as electrostatic devices are now also included. Capability of second order calculations of such elements for a multi charge state beam has been implemented. Benchmarking of the code, in particular for a multi-charge state beam is discussed. Comparison of beam simulations results with beam measurements on the MSU ReAccelerator (ReA) are reported. The possibility of using DYNAC as an online tool for ReA and FRIB is discussed.
*DYNAC: A Multi-Particle Beam Dynamics Code for Leptons and Hadrons, E.Tanke et al,LINAC2002
**HERSC: A New 3 Dimensional Space Charge Routine for High Intensity Bunched Beams, E.Tanke et al,LINAC2002

THPB094

Performance of Beam Chopper at SARAF via RF Deflector Before the RFQ

rfq, ion, proton, ion-source

1038

A. Shor, D. Berkovits, I. Fishman, A. Grin, B. Kaizer, L. Weissman
Soreq NRC, Yavne, Israel

We describe performance of a beam chopper at the SARAF accelerator consisting of an HV deflector preceding the RFQ. The deflector and electronics, developed at LNS Catania, was designed to provide slow beam chopping for beam testing and diagnostics where low beam power is necessary. The HV deflector sweeps away the low energy beam onto a water cooled beam catcher, while a fast HV switch momentarily switches off the HV whenever a transmitted beam to the RFQ is desired. We report on measurements with this chopping system, where minimum transmitted beam pulse of 180 ns duration is attained with a rise and fall time of several nano-seconds. We performed beam dynamics simulations of SARAF Phase-I, including the deflector, where the short rise and fall times of the chopped beam is attributed to the tight collimation of the deflected beam provided by the RFQ and the fast Faraday Cup. We also describe beam dynamics simulations which suggest that single RFQ bunch selection can be achieved with the existing chopping system, during zero-crossover for positive-negative deflecting HV waveform.

THPB095

Designing of a Phase-mask-type Laser Driven Dielectric Accelerator for Radiobiology

laser, electron, acceleration, vacuum

1041

K. Koyama
UTNL, Ibaraki, Japan
A. Aimidura, M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
Y. Matsumura
University of Tokyo, Tokyo, Japan
T. Natsui, M. Yoshida
KEK, Ibaraki, Japan

Funding: This work is supported by KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120
In order to estimate the health risk of a low radiation dose, basic processes of the radiobiology should be clarified by shooting a DNA using a spatially and temporary defined particle beam or X-ray. A suitable beam size is as small as a resolving power of an optical microscope of a few hundred nanometers. Photonic crystal accelerators (PCA) are capable of delivering nm-beams of sub-fs pulses because the characteristic length and frequency of PCAs are on the order of the laser light. Since the phase-mask type accelerator has a simpler structure than other types of PCAs, we are designing a phase-mask type laser driven dielectric accelerator. By adopting an unbalanced length of pillar and ditch (grating) of 4:1, a standing wave like acceleration field is produced in a acceleration channel. A pillar height and initial speed of injected electron are determined by analytically. The maximum acceleration gradient of 2 GeV/m is estimated. The required laser power is roughly estimated to be 6.5 GW. The simulation using CST-code also shows similar values to accelerate electrons by the phase-mask type accelerator.