| Paper | Title | Page |
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| TUPB001 | The Fine Structure of the Zone of Particle Interaction with a Finite Length Periodic Structure | 473 |
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| 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. | ||
| TUPB002 | Deflecting Structures with Minimized Level of Aberrations | 476 |
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Funding: in part RBFR N 12-02-00654a Deflecting structures are now widely used for bunch phase space manipulations either in bunch rotation for special bunch diagnostic or in emittance exchange experiments. As a tool for manipulation, the structure itself should provide the minimal phase space perturbations due to non linear additives in the field distribution. Even if the field of synchronous harmonic is aberration free, the higher space harmonics provide significant non linear additives in the field distribution, leading to emittance growth during phase space manipulation. Criterion of the field quality estimation is developed and deflecting structures are considered for minimization of non linear additives. Examples with almost aberration free total field distributions are presented. |
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| TUPB004 | Results of Testing of Multi-beam Klystrons for the European XFEL | 479 |
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| For the European XFEL multi-beam klystrons, which can produce RF power of 10 MW at an RF frequency of 1.3 GHz, at 1.5ms pulse length and 10 Hz repetition rate, were chosen as RF power sources. Twenty-seven of horizontal multi-beam klystrons (MBK) together with connection modules (CM) will be installed in the XFEL underground tunnel. The CM will be installed on the MBK and connects the MBK to the pulse transformer with only one HV cable, because the CM has a filament transformer inside as well as all diagnostics for HV and cathode current measurements. MBK prototypes together with CM prototypes have been tested for long time at a test stand at DESY, about 3000 hours of operation for each of horizontal MBK with full RF output power, full pulse length and repetition rate of 10 Hz. Testing of first MBKs from series production has been started. In this paper we will give an overview of the test procedure, summarize the current test results and we will give a comparison of the most important parameters. | ||
| TUPB005 | Computational Model Analysis for Experimental Observation of Optical Current Noise Suppression Below the Shot-noise Limit | 482 |
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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) |
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| TUPB006 | Stability Performance of the Injector for SACLA/XFEL at SPring-8 | 486 |
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| To realize the SACLA, it is necessary to obtain stabilities of 10-4 and 50 fs in the amplitude and time of an acceleration voltage, respectively. The achievement of the rf stabilities were almost satisfactory for the target values. Consequently, the 7 GeV beam energy stability was 0.02% (std.) or less. However, there was XFEL power variation caused by a variation of a beam position in a 40 MeV injector section. A periodically changed beam position of 40 μm (std.) was found out at a cycle of 2 s by Fourier transform method using BPM data. The temperatures of all the injector rf cavities are controlled within 28±0.04˚C by a controller using the cooling water. The AC power supplies of the controller to heat the cooling water are operated at 0.5 Hz by pulse width modulation control with alternatively turning on or off. The strong correlation between laser intensity variation and the modulation frequency of the AC power supplies was found out. We are planning to improve the cavity temperature variation in the order of less than 0.01˚C with DC power supplies to establish continuously regulated the cavity temperature. This plan will reduce the XFEL power variation. | ||
| TUPB008 | Major Trends in Linac Design for X-ray FELs | 489 |
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Funding: This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-06CH11357. Major trends in the contemporary linac designs for x-ray free-electron lasers (XFELs) are outlined starting with identification of the key performance parameters, continuing with considerations of the design options for the electron gun and linac, and finishing with electron beam manipulation in the phase space. |
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| TUPB009 | C-Band Accelerating Structure Development and Tests for the SwissFEL | 492 |
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| SwissFEL requires a 5.8 GeV beam provided by a C-band linac consisting of 104 two-meter accelerating structures. Each structure is of the constant gradient type and is composed of 113 cups. The cup shape is double-rounded to increase the quality factor. No tuning feature is implemented. For this reason ultra-precise turning is exploited. A strong R&D program has been launched on structure fabrication, which will be followed by a future technology transfer to a commercial company. The program includes the production and test of short structures that can be brazed in the existing PSI vacuum oven and will be completed with the production of the full two-meter prototype once the new full scale brazing oven, presently under construction, is operational. The status of the R&D program, including the production and power test results of the first two test structures, is reported here. | ||
| TUPB010 | The Swiss FEL RF Gun: RF Design and Thermal Analysis | 495 |
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| We report here on the design of a dual-feed S-band 2.5 cell RF gun, developed in the framework of SwissFEL, capable of operating at 100 Hz repetition rate. As in the LCLS RF gun, z-coupling, to reduce the pulsed surface heating, and a racetrack coupling cell shape, to minimize the quadrupolar component of the fields, have been adopted. The cell lengths and the iris thicknesses are as in the PHIN gun operating at CERN. However the irises aperture has been enlarged to obtain a frequency separation between the operating π mode and the π/2 mode higher than 15 MHz. An amplitude modulation scheme of the RF power, which allows one to obtain a flat plateau of 150 ns for multibunch operation and a reduced average power is presented as well. With an RF pulse duration of 1μs it is shown that operation at 100 MV/m and 100 Hz repetition rate is feasible with very reasonable thermal stresses. | ||
| TUPB011 | The Swiss FEL S-Band Accelerating Structure: RF Design | 498 |
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| The Swiss FEL accelerator concept consists of a 450 MeV S-band injector Linac at 2998.8 GHz followed by the main linac at the C-band frequency aiming at a final energy of 5.8 GeV. The injector has six four-meter long S-band accelerating structures that shall operate with gradients up to 20 MV/m and with a 100 Hz repetition rate. Each structure has 122 cells, including the two coupler cells and operates with a 2π/3 phase advance. The design presented is such that the average dissipated RF power is constant over the whole length of the structure. The cells consist of cups and the cell irises have an elliptical profile to minimize the peak surface electric field. The coupler cells are of the double-feed type with a racetrack cross-section to cancel the dipolar components of the fields and to minimize its quadrupolar components. | ||
| TUPB012 | The Swiss FEL C-Band Accelerating Structure: RF Design and Thermal Analysis | 501 |
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| The Swiss FEL accelerator concept consists of a 450 MeV S-band injector linac followed by the main linac in C-band aiming at a final energy of 5.8 GeV. The two-meter long C-band accelerating structures have 113 cells, including the two coupler cells, and operate with a 2π/3 phase advance. The structure is of the constant-gradient type with rounded wall cells and has an average iris radius of 6.44 mm, a radius compatible with the impact of the short-range wakefields on the whole linac beam dynamics. The cell irises have an elliptical profile to minimize the peak surface electric fields and the coupler cells are of the J-type. We report here on the RF design of the structure, as well as on its thermal analysis, to target operational conditions with an accelerating gradient of about 28 MV/m and a repetition rate of 100 Hz. | ||
| TUPB013 | Update on the Commissioning Effort at the SwissFEL Injector Test Facility | 504 |
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| The SwissFEL Injector Test Facility at the Paul Scherrer Institute is the principal test bed and demonstration plant for the SwissFEL project, which aims at realizing a hard-X-ray Free Electron Laser by 2017. Since the spring of 2012 the photoinjector facility has been running with all RF cavities in full operation, allowing beam characterization at energies around 230 MeV with bunch charges between 10 and 200 pC. We give an overview of recent commissioning efforts with particular emphasis on efforts to optimize the emittance of the uncompressed beam. | ||
| TUPB014 | Comparative Design of Single Pass, Photo-cathode RF-LINAC FEL for the THz Frequency Range: Self Amplification vs. Enhanced Super-radiance | 507 |
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| Self amplified spontaneous emission and enhanced super-radiance are discussed and compared as possible configurations in the construction of a single-pass, photo-cathode RF-LINAC FEL source for THz radiation, being developed in Ariel University Center of Samaria. Numerical simulations carried out using 3D, space-frequency approach demonstrate the charge squared dependence of the radiation power in both cases, the characteristic typical to super-radiant emission. The comparison reveals a high efficiency of an enhanced super-radiance FEL, which however can only be achieved with ultra-short (the radiation wavelength long or shorter) drive electron beam bunches at a proper energy chirping. | ||
| TUPB015 | Warm Beamlines and Infrastructure in the European XFEL | 510 |
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| The European XFEL is driven by a superconducting linear accelerator. In the main accelerator tunnel the accelerator modules will be suspended from the tunnel ceiling. The warm sections like bunch compressors will be installed on girders supported from the floor. The accelerator infrastructure like klystrons and electronic racks will be installed in the accelerator tunnel in close proximity to the electron beamline. | ||
| TUPB018 | Study of Beam-Based Alignment for Shanghai Soft X-Ray FEL Facility | 513 |
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| 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. | ||
| TUPB019 | Second CW and LP Operation Test of XFEL Prototype Cryomodule | 516 |
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| In summer 2011, we have performed the first test of continuous wave (cw) and long pulse (lp) operation of the XFEL prototype cryomodule, which originally has been designed for short pulse operation. In April and June 2012, the second test took place, with the next cryomodule prototype. For that test cooling in the cryomodule was improved and new LLRF system has been implemented. In this contribution we discuss results of the second RF test of these new types of operation, which can in the future extend flexibility in the time beam structure of the European XFEL facility | ||
| TUPB020 | Status of the European XFEL 3.9 GHz system | 519 |
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| The third harmonic system at 3.9 GHz of the European XFEL injector section will linearize the bunch RF curvature, induced by first accelerating module, before the first compression stage. This paper presents qualification tests on cavity prototypes and the on-going activities towards the realization of the third harmonic section of the European XFEL in view of its commissioning in 2014. | ||
| TUPB021 | Study of Plasma Effect in Longitudinal Space Charge Induced Microbunching Instability | 522 |
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The longitudinal space charge (LSC) plays an important role in introducing the microbunching instability in the LINAC of a free electron laser (FEL) facility. The current model of LSC impedance [1] derived from the fundamental electromagnetic theory [2] is widely used to explain the growth of the microbunching instability [3]. However, in the case of highly bright relativistic electron beams, the plasma effect starts to play a role. In this article, the basic model of LSC impedance including the plasma effect is built , and the modifications to the microbunching instability based on the new model are discussed in various conditions.
[1] Marco Venturini, Phys Rev. ST Accel. Beams 11, 034401 (2008) [2] J. D. Jackson, Classical Electrodynamics (Wiley, 1999) [3] Z. Huang, et. al., Phys, Rev. ST Accel. Beams 7, 074401 (2004) |
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| TUPB022 | A Passive Linearizer for Bunch Compression | 525 |
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| In high gain free electron laser (FEL) facility design and operation, a high bunch current is required to get lasing with a reasonable gain length. Because of the current limitation of the electron source due to the space charge effect, a compression system is commonly used to compress the electron beam to the exact current needed. Before the bunch compression, the nonlinear energy spread due to the finite bunch length should be compensated; otherwise the longitudinal profile of bunch will be badly distorted. Usually an X band accelerating structure is used to compensate the nonlinear energy spread while decelerating the beam. For UV FEL facility, the X band system is too expensive comparing to the whole facility. In this paper, we present a corrugated structure as a passive linearizer, and the preliminary study of the beam dynamics is also shown. | ||
| TUPB023 | The Optimization of RF Deflector Input Power Coupler | 528 |
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| 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. | ||
| TUPB026 | Measurements of a Reduced Energy Spread of a Recirculating Linac by Non-isochronous Beam Dynamics | 531 |
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Funding: supported by DFG through SFB 634 The Superconducting Linear Accelerator S-DALINAC at the University of Darmstadt (Germany) is a recirculating linac with two recirculations providing beams for measurements in nuclear physics at small momentum transfers. For these experiments an energy spread of better than 10-4 (rms) is needed. Currently acceleration in the linac section is done on crest of the accelerating field. The recirculation path is operated achromatic and isochronous. In this recirculation scheme the energy spread of the resulting beam in the ideal case is determined by the electron bunch length. Taking into account the stability of the RF system the energy spread increases drastically to more than 10-3 (rms). We will present a new non-isochronous recirculation scheme which helps cancelling out these errors from the rf-control. This scheme uses longitudinal dispersion in the recirculation paths and an acceleration off-crest with a certain phase with respect to the maximum. We will present results of the commissioning of the new system including measurements of the longitudinal dispersion in the recirculation arcs as well as measurements of the resulting energy spread using an electron spectrometer. |
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| TUPB028 | Status of the Rare Isotope Science Project in Korea | 534 |
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Funding: National Research Foundation of Korea A heavy-ion accelerator facility is being designed in Korea for the production of rare isotope beams under the name of rare isotope science project (RISP). The project is funded and officially started in Jan. 2012. The accelerator complex is composed of three main accelerators: a superconducting linac to use in-flight fragmentation (IF) method in generating isotope beams, a 70 kW proton cyclotron for the ISOL method, and a superconducting post accelerator for re-acceleration of rare isotope beams to the energy range of 18 MeV/u. The minimum energy of a U beam required for the IF driver is 200 MeV/u at the beam power of 400 kW. The beam current of U ions in high charge states is limited by the performance of existing ECR ion sources. This facility will be unique in the aspect that state-of-art accelerators are facilitated for both the IF and ISOL drivers and combined to produce extreme exotic beams. Also, standalone operation of each accelerator will allow us to accommodate diverse users from beam application fields as well as nuclear physics. The current status of the design efforts will be presented. |
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| TUPB029 | Beam Intensity and Energy Control for the SPIRAL2 Facility | 537 |
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| The first part of the SPIRAL2 facility, which entered last year in the construction phase at GANIL in France, consists of an ion source, a deuteron and a proton source, a RFQ and a superconducting linear accelerator delivering high intensity, up to 5mA and 40 MeV for the deuteron beams. Diagnostic developments have been done to control the intensity and the beam energy by non-interceptive methods at the linac exit. The beam current is measured by using couples of ACCT-DCCT installed along the lines and the beam energy by using a time of flight device. This paper gives explanations about the technical solutions, the results and resolutions for measuring and controlling the beam. | ||
| TUPB030 | Overview of the Superconducting Linacs of the Rare Isotope Science Project | 540 |
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| The Rare Isotope Science Project is launched in Korea to build a IF and ISOL facilities. The IF driver superconducting linac is to accelerate ion beams up to 200 MeV/u for U beam and 600 MeV for proton beam. The ISOL post linac is a superconducting linac to accelerate up to 18 MeV/u for U beam. General layout of SC linac is discussed. | ||
| TUPB031 | Beam Envelope Analysis and Simulation | 543 |
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| 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. | ||
| TUPB032 | Beam Dynamics of the Linac ALPI-PIAVE in View of Possible Upgrades Scenario for the SPES Project. | 546 |
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| At the Legnaro National Laboratories it is operating a Super Conducting linac for nuclear studies named ALPI. The ALPI linac is injected either by a XTU tandem, up to 14 MV, or by the s-c PIAVE injector, made with 2 SC-RFQ. In this article will be report the beam dynamics simulations for some possible scenario upgrade of the linac operate by a new injector, made with a new RFQ. | ||
| TUPB033 | Piezoelectric Actuator Based Phase Locking System for IUAC Linac | 549 |
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| The linac of IUAC consists of three main accelerating modules with each one housing eight superconducting quarter wave resonators. Currently, the phase locking of the resonator is performed by a combination of fast I-Q based electronic tuner and helium gas flow based mechanical tuner. Microphonics measurement on the resonators found the presence of lower frequency vibrations along with main mechanical mode (~60 Hz) of the resonators. Although main mechanical mode of the resonator is damped by using SS balls, the presence of lower frequency vibrations demand more RF power from the amplifier, as the existing mechanical tuner works in time scale of seconds. A combination of piezoelectric actuator based fast tuner along with stepper motor based coarse tuner operating in the time scale of milliseconds is being developed. This scheme is implemented on a few resonators in last linac cryostat. Initial results show that this mechanism can arrest all low frequency vibrations thereby reducing a substantial load from the electronic tuner and improve the dynamics of the phase locking scheme. The implementation scheme along with test results will be presented in detail. | ||
| TUPB034 | A Helium Injector for Coupled RFQ and SFRFQ Cavity Project at Peking University | 552 |
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| A new acceleration structure named as coupled RFQ and SFRFQ cavity is under design at Peking University (PKU). A pulsed He+ beam injector will be needed to transport 30 keV 20 mA He+ beam with a factor of 1/6, pulse width of 1 ms and normalized rms emittance less than 0.15 π{·}mm{·}mrad for this composited type cavity. Based on the experimental results obtained on the PKU LEBT test bench, a 1.16 m long two-solenoid type low energy beam transport (LEBT) line was developed. In this paper we will address the 30 keV He+ ion beam transportation experiment results on the test bench as well as the specific design on the helium injector. | ||
| TUPB035 | A New Design of the RFQ Channel for GSI HITRAP Facility | 555 |
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| 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 | 558 |
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| 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. | ||
| TUPB039 | Conceptual Design of Superconducting Heavy Ion Linear Injector for HIAF | 561 |
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| A heavy ion accelerator facility, High Intensity Heavy Ion Accelerator Facility (HIAF), has been promoted by Institute of Modern Physics （IMP）of Chinese Academy of Sciences (CAS). The injector of the accelerator facility is a superconducting linac. It is a high intensity heavy ion linac and works on pulse mode. The final energy is 150 MeV/u. The accelerated species are from P to Uranium. The linac works with both laser and ECR ion source. The designed current is 20 emA. The general concept of HIAF and the preliminary design of linear injector are presented in the paper. | ||
| TUPB040 | Status of the Linac SRF Acquisition for FRIB | 564 |
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Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE SC0000661. The Facility for Rare Isotope Beams (FRIB) will utilize a high-intensity, superconducting heavy-ion driver linac to provide stable ion beams from protons to uranium up to energies of >200 MeV/u and at a beam power of up to 400 kW. The ions are accelerated to about 0.5 MeV/u using a room-temperature 80.5 MHz RFQ and injected into a superconducting cw linac consisting of 330 individual low-beta cavities in 49 cryomodules operating at 2 K. This paper discusses the current status of the linac SRF acquisition strategy as the project phases into construction mode. |
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| TUPB041 | Scattering of H− Stripped Electrons from SEM Grids and Wire Scanners at the CERN LINAC4 | 567 |
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| 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%. | ||
| TUPB042 | Progress on RFQIII Fabrication in J-PARC Linac | 570 |
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| The J-PARC accelerator comprises an injector linac, a 3 GeV Rapid-Cycling Synchrotron and a 50 GeV Main Ring. The J-PARC linac has been operating for users with the beam energy of 181 MeV. The energy (to 400 MeV) and current (to 50 mA) upgrade of the linac is scheduled for 1MW operation at RCS. For the current upgrade, the fabrication of a new RFQ, which is designed for 50 mA acceleration, has been started. The engineering design and the fabrication technologies were carefully chosen to reduce the discharge risk during the operation. For good vacuum pumping, vanes and ports are brazed for the direct pumping through slits at the tuners. Also, we tried a chemical polishing to improve the smoothness of the vane surface. In this paper, we present the fabrication progress of a new RFQ in J-PARC linac. | ||
| TUPB043 | One Design of Heavy Ion Linac Injector for CSRm | 573 |
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| The design of heavy ion linac as one new injector of the main Cooling Storage Ring (CSRm) has been discussed. The linac design is based on interdigital H mode drift tube with KONUS (Kombinierte Null Grad Struktur). A high acceleration rate with zero degree synchronous particle phase acceleration reduce the length of IH-KONUS linac and the cost in comparison with conventional linac based on Alvarez structure. To reduce the effect of emittance growth, the RFQ structure is used in front of the IH-KONUS linac. In this linac, the design particle 238U28+ will be accelerated to 7 AMeV, and the transmission of Uranium beam can reach up to 80%. In this report, the initial physics design of the main linac is presented. | ||
| TUPB044 | Cryogenic System for the ADS Injector II in IMP, CAS | 576 |
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Funding: Work supported by Accelerator Driven Sub-critical (ADS) program of CAS, China In order to meet the requirements of ADS Injector II project which is now being designed and built in IMP, CAS, a liquid helium cryogenic system with 4.5K & 850W cooling power is being built. This paper presents the primary design and the status of this cryogenic system with different operation models according to the need of superconducting tests. guoxh@impcas.ac.cn |
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| TUPB046 | R&D Towards CW Ion Linacs at ANL | 579 |
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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, DE-AC02-06CH11357 and ANL WFO 85Y47. The accelerator development group in ANL’s Physics Division has engaged in substantial R&D related to CW proton and ion accelerators. Particularly, a 4 meter long 60.625 MHz CW RFQ has been developed, built and is being commissioned with beam. Development and fabrication of a cryomodule with seven 72.75 MHz quarter-wave cavities is complete and it is being assembled. Off-line testing of several QWRs has demonstrated outstanding performance in terms of both accelerating voltage and surface resistance. Both the RFQ and cryomodule were developed and built to upgrade ATLAS to higher efficiency and beam intensities. Another cryomodule with eight 162.5 MHz SC HWRs and eight SC solenoids is being developed and built for Project X at FNAL. We are also developing both an RFQ and cryomodules (housing 176 MHz HWRs) for proton & deuteron acceleration at SNRC (Soreq, Israel). In this paper we discuss ANL-developed technologies for normal-conducting and SC accelerating structures for medium- and high-power CW accelerators, including the projects mentioned above and other developments for applications such as transmutation of spent reactor fuel. |
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| TUPB047 | Status of the Superconducting RF Activities for the HIE ISOLDE Project | 582 |
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| The planned upgrade of the REX ISOLDE facility at CERN will boost the energy of the machine from 3 MeV/u up to 10 MeV/u with beams of mass-to-charge ratio 2.5 < A/q < 4. For this purpose, a new superconducting post accelerator based on independently phased 101.28 MHz Quarter Wave Resonators (QWR) will replace part of the normal conducting Linac. The QWRs make use of the Niobium sputtering on Copper technology which was successfully applied to LEP2, LHC and to the energy upgrade of the ALPI Linac at INFN-LNL. The status of advancement of the project will be detailed, limited to the SRF activities. | ||
| TUPB048 | Discussion of the Optimisation of a Linac Lattice to Minimise Disruption by a Class of Parasitic Modes | 585 |
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| 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. | ||
| TUPB049 | Superconducting Low Beta Niobium Resonator for Heavy Ions | 588 |
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| For the high current injector at Inter-University Accelerator Centre, a new superconducting niobium resonator optimized for β = 0.05 operating at 97 MHz, has been designed and fabricated. This resonator has the highest frequency in its class among the superconducting structures designed for such low velocity particles. The resonator has been carefully modeled using Microwave Studio code to minimize the peak magnetic field in order to achieve high accelerating gradients in it. Even though the resonance frequency is high, the physical dimensions of the resonator are large enough to allow processing of its superconducting surface effectively. The mechanical design of the resonator has been modeled using ANSYS multiphysics to increase the frequency of the lowest mechanical eigenmode of the central co-axial line, and also reduce liquid helium induced pressure fluctuations in the resonator. Bead pull measurements have been performed on the niobium resonator and they match with the design values very well. Cold tests at 4.2 K will be performed in the next few weeks. This paper will briefly present the design of the low beta resonator and details of the results from the cold tests. | ||
| TUPB052 | Studies of Parasitic Cavity Modes for Proposed ESS Linac Lattices | 591 |
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| 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. | ||
| TUPB053 | Main Coupler Design for Project X | 594 |
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| A multi-megawatt proton/H− source, Project X, is under development at Fermi National Accelerator Laboratory. Main element of it is a 3 GeV superconducting proton linac which includes 5 families of superconducting cavities of three frequencies: 162.5, 325 and 650 MHz. Scope of this paper is the development of power couplers for 325 and 650 MHz at FNAL. Upgraded version of the accelerator will require two types of couplers, which reliably can operate at CW power level ~25 kW at 325 MHz and ~100 kW at 650 MHz respectively. In this paper we are describing the current design of these devices. | ||
| TUPB054 | Coherent Effects of High Current Beam in Project-X Linac | 597 |
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| Resonance excitation of longitudinal high order modes in superconducting RF structures of Project X CW linac is studied. We analyze regimes of operation of the linac with high beam current, which can be used to provide an intense muon source for the future Neutrino Factory or Muon Collider, and also important for the Accelerator-Driven Subcritical (ADS) systems. We calculate power loss and associated heat load to the cryogenic system. Longitudinal emittance growth is estimated. We consider an alternative design of the elliptical cavity for the high energy part of linac, which is more suitable for high current operation. | ||
| TUPB055 | R&D of IMP Superconducting HWR for China ADS | 600 |
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| 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 | 603 |
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| 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 | 606 |
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| 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 | 609 |
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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. |
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| TUPB060 | Multipacting Suppression Modeling for Half Wave Resonator and RF Coupler* | 612 |
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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. |
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| TUPB061 | ADRC Control for Beam Loading and Microphonics | 615 |
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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. |
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| TUPB062 | Longitudinal Dynamic Analysis for the Project X 3-8 GeV Pulsed Linac | 618 |
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| The Pulsed Linac is a will require over 200 9-cell, 1300 MHz cavities packed in 26 ILC type cryomodules to accelerate 1 mA average beam current from 3GeV to 8 GeV. The architecture of the RF must optimize RF power, beam emittance, and energy gain amid a large number of requirement and constraints. The pulse length is a critical issue. Ideally, a 26 ms pulse would allow direct injection into the Fermilab’s Main Injector, bypassing the need of the Fermilab’s Recicler. High loaded quality factors (QL) are also desirable to minimize RF power. These requirements demand an accurate control of the cavity resonant frequency disturbed by Lorentz Force Detuning and microphonics. Also the LLRF control system must regulate the RF amplitude and phase within tight bounds amid a long list of dynamic disturbances. The present work describes the simulation efforts and measurements at Fermilab facilities. | ||
| TUPB066 | Reduced-beta Cavities for High-intensity Compact Accelerators | 621 |
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Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under contract number DE-AC02-06CH11357 and WFO 8R268. This paper reports on the development and testing of a superconducting quarter-wave and a superconducting half-wave resonator. The quarter-wave resonator is designed for β = 0.077 ions, operates at 72 MHz and can provide more than 7.4 MV of accelerating voltage at the design beta, with peak surface fields of 164 mT and 117 MV/m. Operation was limited to this level not by RF surface defects but by our available RF power and administrative limits on x-ray production. A similar goal is being pursued in the development of a half-wave resonator designed for β = 0.29 ions and operated at 325 MHz. |
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| TUPB067 | Development of a Superconducting Half-Wave Resonator for PXIE | 624 |
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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. |
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| TUPB068 | Cryomodule Designs for Superconducting Half-Wave Resonators | 627 |
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Funding: This work was supported by the U.S. DOE, Office of Nuclear Physics, contract number DE-AC02-06CH11357, WFO 85Y47 supported by SNRC, and WFO 82308 supported by Fermi National Accelerator Laboratory. In this paper we present advanced techniques for the construction of half-wave resonator cryomodules. Recent advances in superconducting low-beta cavity design and processing have yielded dramatically improved cavity performance which reduce accelerator cost and improve operational reliability. This improvement has led to the proposal and construction of half-wave resonators by ANL for the acceleration of 0.1 < \beta < 0.5 ions, e.g., the SARAF Phase-II project at SNRC (SOREQ, Israel) and Project-X at Fermilab. These cryomodules build and improve upon designs and techniques recently implemented in upgrades to ATLAS at ANL. Design issues include the ease of assembly/maintenance, resonator cleanliness, operating at 2 or 4 Kelvin, and ancillary system interfacing. |
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| TUPB069 | BEAMDULAC-SCL Code for Complex Approach of Beam Dynamic Investigation in SC LINAC | 630 |
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| 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. | ||
| TUPB070 | Development of Proton Therapy at the SC Linac with BEAMDULAC-SCL Code | 633 |
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Proton cancer therapy complexes are conventionally developing based on synchrotrons and cyclotrons. High electrical power consumption and especial devices necessary to energy variation (as slow extraction systems and degraders) are the main problems of such complexes. At once SC linacs based on short independently phased quarter and half wave cavities have a serious progress at present. Linear accelerator consumes less power comparably with cyclic and the energy variation can be easily realized by means of RF field amplitude and phase variation in a number of cavities. The accelerator’s modular configuration which is now widely used in FRIBs * or SNSs can be applied for therapy linac also (see for example **). It is possible to choose the SC linac parameters and proton and ion beams stability study with help of the BEAMDULAC-SCL code. This software also allows providing of the structure optimization and the beam dynamics control.
* P.N. Ostroumov and et al., Proc. of PAC2001, p.4080. ** C.Ronsivalle et al. Proc. of IPAC 2011, p. 3580. |
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| TUPB071 | First Measurements on the 325 MHz Superconducting CH Cavity | 636 |
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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. |
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| TUPB072 | Status of the Superconducting CW Demonstrator for GSI | 639 |
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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. |
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| TUPB073 | Design and Simulation of a Test Model for a Tri-Spoke Cavity at RIKEN | 642 |
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| 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. | ||
| TUPB074 | Superconducting CW Heavy Ion Linac at GSI | 645 |
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Funding: Helmholtz Institute Mainz (HIM) An upgrade program has to be realized in the next years, such that enhanced primary beam intensities at the experiment target are available. For this a new sc 28 GHz full performance ECR ion source is under development. Via a new low energy beam line an already installed new RFQ and an IH-DTL will provide for cw-heavy ion beams with high average beam intensity. It is planned to build a new cw-heavy ion-linac behind this high charge state injector. In preparation an R&D program is still ongoing: The first linac section comprising a sc CH-cavity embedded by two sc solenoids (financed by HIM) as a demonstrator will be tested with beam at the GSI High Charge Injector (HLI).The new linac should feed the GSI flagship experiments SHIP and TASCA, as well as material research, biophysics and plasma physics experiments in the MeV/u-area. The linac will be integrated in the GSI-UNILAC-environment; it is housed by the existing constructions. Different layout scenarios of a multipurpose high intensity heavy ion facility will be presented as well as the schedule for preparation and integration of the new cw-linac. |
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| TUPB075 | Beam Dynamics Design of China ADS Proton Linac | 648 |
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Funding: Supported by China ADS Program(XDA03020000), National Natural Science Fundation of China (10875099) and IHEP Special Fundings(Y0515550U1) It is widely accepted that the Accelerator Driven System (ADS) is one of the most promising technical approach to solve the problem of the nuclear wastes, a potential threaten to the sustainable development of the nuclear fission energy. An ADS study program is approved by Chinese Academy of Sciences at 2011, which aims to design and built an ADS demonstration facility with the capability of more than 1000 MW thermal power within the following 25 years. The 15 MW driver accelerator will be designed and constructed by the Institute of High Energy Physics(IHEP) and Institute of Modern Physics(IMP) of China Academy of Sciences. This linac is characterized by the 1.5 GeV energy, 10mA current and CW operation. It is composed by two parallel 10 MeV injectors and a main linac integrated with fault tolerance design. The superconducting acceleration structures are employed except the RFQ. In this paper the general considerations and the beam dynamics design of the driver accelerator will be presented. |
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| TUPB077 | Thorium Energy | 651 |
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| The potential for using thorium as an alternative or supplement for uranium in fission power generation has long been recognised, with growing concerns over nuclear waste, safety and proliferation. Thorium may be used in solid fuel form, or in molten salt systems. In some approaches the fuel can incorporate components from spent nuclear fuel (minor actinides, plutonium) to also serve a transmutation function. We consider the benefits and drawbacks of using an accelerator driven subcritical system, for both solid fuel and molten salt cases, in particular addressing the power and reliability requirements of the accelerator. We outline the research that will be necessary to lead to an informed choice. | ||
| TUPB079 | Design and Beam Test of Six-Electrode BPMs for Second-Order Moment Measurement | 654 |
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| In the SPring-8 linac, four-electrode beam position monitors (BPMs) have been utilized for the measurement of the transverse first-order moments, which correspond to the centroids of beam charge distributions. We have planed to measure the transverse second-order moments of beams to obtain information of beam optics and its energy deviations during the top-up beam injection without destruction of beams. Therefore, six-electrode BPMs with circular and quasi-ellipse cross-sections have been developed on the basis of a newly introduced theory. A low-noise signal processor for the six-electrode BPM has also been developed to perform fine measurement. We expected the following resolutions determined by the S/N ratio of the circuit; the first order moments (beam positions) >1 μm, and the second order moments with a size >110 μm. The first beam test was carried out using the six-electrode BPM with circular cross-section and the old signal processor. The measured sensitivities and resolutions of the second-order moments showed good agreement with the theory. | ||
| TUPB080 | Non-destructive Real-time Monitor to Measure 3D Bunch Charge Distribution with Arrival Timing to Maximize 3D Overlapping for HHG-Seeded EUV-FEL | 657 |
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| Non-destructive, shot-by-shot real-time monitors have been developed to measure 3D bunch charge distribution (BCD). This 3D monitor has been developed to monitor 3D overlapping electron bunches and higher harmonic generation (HH) pulses in a seeded VUV-FEL. This ambitious monitor is based on an Electro-Optic (EO) multiple sampling technique in a manner of spectral decoding that is non-destructive and enables real-time measurements of the longitudinal and transverse BCD. This monitor was materialized in simultaneously probing eight EO crystals that surround the electron beam axis with a radial polarized and hollow EO-probe laser pulse. In 2009, the concept of 3D-BCD monitor was verified through electron bunch measurements at SPring-8. The further target of the temporal resolution is ~30 fs (FWHM), utilizing an organic EO crystal (DAST) instead of conventional inorganic EO crystals (ZnTe, GaP, etc.) The EO-sampling with DAST crystal is expected to measure a bunch length less than 30 fs (FWHM). In 2011, the first bunch measurement with an organic EO crystal (DAST) was successfully demonstrated in the VUV-FEL accelerator at SPring-8. | ||
| TUPB081 | Beam Diagnostics Development for Triumf E-Linac | 660 |
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| TRIUMF laboratory is currently in a phase of the construction of a new superconducting 50 MeV 10 mA cw electron linac (e-linac) to drive photo-fission based rare radioactive isotope beam (RIB) production. The project imposes certain technical challenges on various accelerator systems including beam diagnostics. In the first place these are a high beam power and strongly varying operating modes ranging from very short beam pulses to the cw regime. A number of development projects have been started to construct the diagnostics instrumentation required for commissioning and operation of the facility. The paper reports the present status of the projects along with measurement results obtained at the test facility which produced the first beam in Fall of 2011. | ||
| TUPB082 | Beam Loss Track Measurements by a Fast Trigger Scheme in J-PARC Linac | 663 |
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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. |
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| TUPB084 | High Dynamic-Range High Speed Linac Current Measurements | 666 |
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Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. It is desired to measure the linac current of a charged particle beam with a consistent accuracy over a dynamic range of over 120 dB. Conventional current transformers suffer from droop, can be susceptible to electromagnetic interference (EMI), and can be bandwidth limited. A novel detector and electronics were designed to maximize dynamic range of about 120 dB and measure risetimes on the order of 10 nanoseconds. |
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| TUPB090 | Development of Permanent Magnet Focusing System for Klystrons | 669 |
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| 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 | 672 |
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| 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. | ||
| TUPB092 | High Power Amplifier Systems for SARAF Phase II | 675 |
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| Soreq NRC initiated the establishment of SARAF - Soreq Applied Research Accelerator Facility. SARAF is based on a continuous wave (CW), proton/deuteron RF superconducting linear accelerator with variable energy (5–40 MeV) and current (0.04-5 mA). RF power to each cavity is driven by a High Power Solid State Amplifiers. The paper outlines the design concept of the 10 and 15 kW at 176 MHz power amplifiers that were designed, built, and 10 kW successfully tested. 15 kW is now under construction. The amplifiers are combined from basic 5.5 kW compact 19" 7U water cooled drawer. | ||
| TUPB093 | Compact 4 kW Variable RF Power Coupler for FRIB Quarter-wave Cavities | 678 |
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| 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 | 681 |
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| 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. | ||
| TUPB095 | Design of Coupler for Direct Coupled Amplifier to Drift Tube Linac Cavities of the Injector RILAC2 for RIKEN RI Beam Factory | 684 |
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| A new linac RILAC2 was constructed at RIKEN RI Beam Factory as an injector for very heavy ions such as uranium and xenon of a high mass to charge ratio m/q ∼ 7, but high intensity ions can be extracted from an ion source. Three drift tube linac cavities, operate in continuous wave mode at 36.5 MHz, have been designed and built. In order to reduce an installation area, and to save a construction cost, we adopted a direct coupling method for a power amplifier without using a long transmission line. A complicated design procedure was performed in order to take into account a change of resonant frequency of the cavity caused by a capacitance of a power tube used in the amplifier. A design of the coupler, as well as the cavity was performed using a three-dimensional electromagnetic calculation code, CST Microwave Studio (MWS). The measured input impedance seen from the amplifier (700 – 1100 Ω) was reproduced well by the calculation of MWS. Also, in order to examine MWS, a case of a coupling with 50 Ω were calculated. The coupling conditions obtained by MWS were compared with the measurement and a calculation with a lumped circuit model. | ||
| TUPB097 | The C-band RF Pulse Compression for Soft XFEL at SINAP | 687 |
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| 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. | ||
| TUPB099 | Input Coupler of the J-PARC DTL | 690 |
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| Each tank of J-PARC DTL has two input couplers. The coupler has a movable coupling loop with an capacitive element which increase the coupling with the tank. The loop position is the outside of the tank, where is the atmosphere. The tank vacuum is kept by the ceramic window on the wall for the coupler port. The ceramic is made of Aluminum oxide of 99.7 % purity. RF properties and the mechanical structure of the coupler were designed adequately in order to achieve the desired performance. We will report the design of the coupler in detail and the experiences for the practical operation of the DTL. | ||
| TUPB100 | Recovery and Status Report of DTL/SDTL for the J-PARC After Earthquake | 693 |
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| The J-PARC facilities had big damages because of the earthquake on March 11, 2011. The J-PARC linac in the tunnel had also damages. For instance the alignment of the cavity was deformed more than 40 mm and there had been observed about 0.2 mm in horizontal direction for a few DTs in the DTL. However, as the result of the recovery work which includes the re-alignment and re-conditioning of whole cavities, we were able to restart the beam acceleration of the linac. The stability of the DTL and SDTL has returned to the state before the earthquake except for a few tanks of SDTL. In this paper, we will present the recovery works from the earthquake and the operating status of the DTL and the SDTL. | ||
| TUPB101 | Beam Loss Occurred at DTL Cavity in J-PARC Linac | 696 |
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| The beam operation of J-PARC linac was suspended until December 2011 due to the damage by the Tohoku earthquake in March 2011. After resumed the operations, we measured the residual radiation along with the beam line during a short interval. Because the higher residual radiation was detected at the surface of drift tube linac (DTL) cavity by radiation survey, we installed the scintillation beam loss monitors (BLM) at the points where the higher radiation was detected to understand the cause of the radiation. Even the DTL section is low energy part of the linac, fine structure of the beam loss was observed by the scintillation BLM. And we measured the beam loss occurred at the DTL with the parameters of beam orbit and cavity settings. Also, the BLM is employed for the linac tuning. In this paper, the result of the radiation measurement and beam loss signals obtained by the scintillation BLMs are presented. | ||
| TUPB102 | Design and Performances of Phase Monitor in J-PARC Linac | 699 |
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| J-PARC linac employs a fast current transformer (FCT) as a beam phase monitor to calculate the beam energy by time-of-flight method. We have installed and used 61 FCTs in the current beam line. Because the phase measurements at additional 41 points in the future ACS sections are required for the energy upgrade project with adding 21 ACS (Annular Coupled Structure) cavities, we stared the design and fabrication of FCTs as the phase measurement devices. In addition, J-PARC linac employs the 4-stripline beam position monitors (BPMs) for the beam position measurement. It has been considered that the signals from striplines of BPM would be useful for a phase measurement. A phase measurement using a BPM has been successfully conducted. In order to evaluate the performances of the FCT, the signal sensitivity and cut-off frequency of newly fabricated FCT are measured. Also, these data of the BPM are also measured to be compared with the data of FCT. Based on the results of the comparing both measurements, the superiority of both monitors for beam phase measurement is discussed. | ||
| TUPB103 | CSNS DTL Prototyping and RF Tuning | 702 |
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| The 324 MHz Alvarez-type Drift Tube Linac (DTL) for the China spallation neutron source will be used to accelerate the H− ion beam of up to 15 mA peak current from 3 to 80 MeV. It consists of four independent tanks, of which the average length is about 8.6 m. Each tank is divided into three short unit tanks about 2.8 m in length for easy manufacture. A full-scale prototype of the first unit tank with 28 drift tubes containing electromagnetic quadrupoles has been constructed to validate the design and to demonstrate the technology. The overall features of the prototype in both key technology and RF tuning are presented. In particular, the influence of the post couplers was studied in the ramped field DTL. | ||
| TUPB104 | Study of the Beam Dynamics in the RISP Driver Linac | 705 |
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| Rare Isotope Science Project (RISP) has been proposed as a multi-purpose accelerator facility for providing beams of exotic rare isotopes of various energies. The RISP driver linac which is used to accelerate the beam, for an example, Uranium ions from 0.3 MeV/u to 200 MeV/u consists of superconducting RF cavities and warm quadrupole magnets for focusing heavy ion beams. Requirement of the linac design is especially high for acceleration of multiple charge beams. In this paper, we present the requirements of dynamic errors and correction schemes to minimize the beam centroid oscillation and preserve beam losses under control. | ||
TUPB105 |
First Operation of the Brookhaven EBIS as the Heavy Ion Preinjector for RHIC | |
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Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. During the 2012 RHIC run cycle, the EBIS-based heavy ion preinjector provided U39+, Au32+ and Cu11+ ions for the RHIC physics program. The preinjector was operated for ~2.5 months continuously. Intensities delivered to the Booster synchrotron were ~109 U39+ ions/pulse, ~1.5·109 Au32+ ions/pulse, and ~6·109 Cu11+ ions/pulse, in ~20 μs pulses. When providing Au and Cu for asymmetric collisions in RHIC, both species were always available, with a switching time between species of 1 second. The performance and operational experience of this new preinjector will be presented. |
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| TUPB107 | Amplitude and Phase Control of the Accelerating Field in the ESS Spoke Cavity | 708 |
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| 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. | ||
| TUPB108 | Uppsala High Power Test Stand for ESS Spoke Cavities | 711 |
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| The European Spallation Source (ESS) is one of the world’s most powerful neutron source. The ESS linac will accelerate 50 mA of protons to 2.5 GeV in 2.86 ms long pulses at a repetition rate of 14 Hz. It produces a beam with 5 MW average power and 125 MW peak power. ESS Spoke Linac consists of 28 superconducting spoke cavities, which will be developed by IPN Orsay, France. These Spoke Cavities will be tested at low power at IPN Orsay and high power testing will be performed at a test stand which will be set up at Uppsala University. The test stand consists of tetrode based RF amplifier chain at 352 MHz, 350 kW power and related RF distribution. Outputs of two tetrodes shall be combined with the hybrid coupler to produce 350 kW power. Preamplifier for a tetrode shall be solid state amplifier. As the spoke cavities are superconducting, the test stand also includes horizontal cryostat, Helium liquefier, test bunker etc. The paper describes features of the test stand in details. | ||