Paper  Title  Other Keywords  Page 

MOP010  A Fast Chopper for the Fermilab High Intensity Neutrino Source (HINS)  linac, vacuum, highvoltage, simulation  73 


A fast chopper capable of kicking single 2.5 MeV H^{} bunches, spaced at 325 MHz, at rates greater than 50 MHz is needed for the Fermilab High Intensity Neutrino Source (HINS). Four 1.2 kV fast pulsers, designed and manufactured by Kentech Instruments Ltd., will drive a ~0.5m long meander made from a copper plated ceramic composite. Test results showing pulses from the prototype 1.2 kV pulser propagating down the meander will be presented. 

MOP024  Low Energy Spread Beam Dynamics and RF Design of a Trapezoidal IHRFQ  rfq, cavity, bunching, ion  115 


Funding: Supported by NSFC (10775009) 

MOP090  Scattering Matrix Simulations of Fields and Dispersion Relations in Superconducting Cavities for XFEL and ILC  scattering, coupling, cavity, simulation  287 


The globalised scattering matrix (GSM) method provides an efficient means of obtaining the electromagnetic field in interconnected multicavity structures. In the proposed XFEL at DESY and the ILC facilities, energetic electron beams can readily excite higher order modes which if left unchecked can dilute the emittance of the beams. The GSM in conjunction with finite element modelling of the scattering matrices of the linac cavities is used to enable the characteristic eigenmodes to be rapidly obtained and the potential for trapped modes is investigated. This characteristic eigensystem allows the wakefield experienced by the beam to be analysed and the consequences on beam quality ascertained. The impact of fabrication errors on the transverse electromagnetic field and corresponding resonant frequencies of the modes is also explored in detailed simulations. 

MOP102  Electron Beam Dynamics in the DARHTII Linear Induction Accelerator  electron, induction, dipole, focusing  311 


Funding: Work supported by USDOE under contract DEAC5206NA25396 *"Longpulse beam stability experiments on the DARHTII linear induction accelerator", Carl Ekdahl, et al., IEEE Trans. Plasma. Sci. Vol. 34, 2006, pp. 460466. 

TUP057  Design and Fabrication of CLIC Test Structures  damping, HOM, acceleratinggradient, wakefield  533 


Demonstration of a gradient of 100 MV/m at a breakdown rate of 107 is one of the key feasibility issues of the CLIC project. A high power rf test program both at Xband (SLAC and KEK) and 30 GHz (CERN) is under way to develop accelerating structures reaching this performance. The test program includes the comparison of structures with different rf parameters, with/without wakefield damping waveguides, and different fabrication technologies namely quadrant bars and stacked disks. The design and objectives of the various Xband and 30 GHz structures are presented and their fabrication methods and status is reviewed. 

THP024  Initial Study on the Shape Optimisation of the CLIC Crab Cavity  cavity, dipole, beamloading, coupling  833 


The CLIC linear collider will require a crab cavity to align bunches prior to collision. Consideration of the bunch structure leads us to favour the use of Xband copper cavities. Due to the large variation of train to train beam loading, it is necessary to minimise the consequences of beam loading. One solution is to use a travelling wave structure with a large group velocity allowing rapid propagation of amplitude errors from the system. Such a design makes this structure significantly different from previous travelling wave deflecting structures. This paper will look at the implications of this on other cavity parameters and the optimization of the cavity geometry. 

THP040  A New TEMType Deflecting and Crabbing RF Structure  cavity, simulation, vacuum, damping  873 


Funding: Supported by US DOE Contract No. DEAC0506OR23177 

THP049  Optimization of SpiralLoaded Cavities Using the 3D Code OPERA/SOPRANO  cavity, resonance, simulation, insertion  900 


Rebunching cavities are today routinely used for matching a beam of charged particles between different accelerator structures, and thus optimizing the overall transmission and beam quality. At low resonance frequencies, unnecessary large dimensions of these cavities can be avoided by using spiralloaded cavities. The optimization of these structures is a complicated process in which a wide range of different parameters have to be modified essentially in parallel. In this contribution, we investigate in detail the characteristics of a model structure with the 3D code OPERA/SOPRANO. This includes the optimization of the structure in terms of the spiral geometry for a given resonance frequency, the investigation of power losses on the inner surfaces, and the possibility of cavity tuning by means of a tuning cylinder. 

THP058  Accelerating Structure for CBand Electron Linear Accelerator Optimization  electron, coupling, vacuum, cavity  921 


The results of analysis and comparison of different linear accelerator designs for 10 MeV facility powered by 4.5 MW klystron on 5712 MHz operation frequencies presented. Several concepts of accelerator including standing wave and traveling wave ones with either rf or magnetic focusing were considered. Cells geometry and beam dynamics parameters in these types of accelerators featuring high capture factor were obtained using numeric simulation methods. The computer simulation code for traveling wave linac optimization based on beam dynamics with space charge consideration was developed. Accelerating structures and input coupler for traveling wave linac along with standing wave one were designed. The task of energy variation was solved. 

THP059  The Cut Disk Structure Parameters for Medium Proton Energy Range  coupling, septum, proton, linac  924 


For intense proton beam acceleration the structure aperture diameter should be ~30 mm. With such aperture room temperature coupled cell accelerating structures have the maximal effective shunt impedance Ze at operating frequency ~650 MHz. For this frequency well known Side Coupled Stricture (SCS), Disk and Washer Structure (DAW), Annular Coupled Structure (ACS) have large transversal dimension, leading to essential technological problems. The Cut Disk Structure (CDS) has been proposed to join high Ze and coupling coefficient kc values, but preferably for high energy linacs. In this report parameters of the four windows CDS option are considered at operating frequency ~700 MHz for proton energy range from 80 MeV to 200 MeV. The cells diameter ~30 cm and kc ~0.12 result naturally, but Ze value is of (0.70.9) from Ze value for SCS (kc=0.03). Small cells diameter opens possibility of CDS applications for twice lower frequency and structure parameters at operating frequency ~ 350 MHz are estimated too. Cooling conditions for heavy duty cycle operation are considered. 



THP062  Design of an XBand Accelerating Structure for the CLIC Main Linac  damping, linac, HOM, acceleratinggradient  933 


The rf design of an accelerating structure for the CLIC main linac is presented. The structure is designed to provide 100 MV/m averaged accelerating gradient at 12 GHz with an rftobeam efficiency as high as 27.7%. The design takes into account both aperture and HOM damping requirements coming from beam dynamics as well as the limitations related to rf breakdown and pulsed surface heating. 

THP064  Development Status of the PiMode Accelerating Structure (PIMS) for Linac4  cavity, coupling, linac, vacuum  939 


The highenergy section of Linac4, between 100 and 160 MeV, will be made of a sequence of 12 sevencell accelerating cavities of the PiMode Structure (PIMS) type, resonating at 352 MHz. Compared to other structures used in this energy range, cavities operating in pimode with a low number of cells have the advantage of simplified construction and tuning, compensating for the fact that the shunt impedance is about 10% lower because of the lower frequency. Field stability in steady state and in presence of transients is assured by the low number of cells and by the relatively high coupling factor of 5%. Standardising the linac rf ystem to a single frequency is considered as an additional economical and operational advantage. The mechanical design of the PIMS will be very similar to that of the 352 MHz normal conducting 5cell LEP accelerating cavities, which have been successfully operated at CERN for 15 years. After reviewing the basic design principles, the paper will focus on the tuning strategy, on the field stability calculations and on the mechanical design. It will also report the results of measurement on a cold model and the design of a fullscale prototype. 

THP065  Shunt Impedance Studies in the ISIS Linac  linac, DTL, simulation, cavity  942 


The ISIS linac consists of four DTL tanks that accelerate a 50 pps, 20 mA H^{} beam up to 70 MeV before injecting it into an 800 MeV synchrotron. Over the last decades, the linac has proved to be a strong and reliable injector for ISIS, which is a significant achievement considering that two of the tanks are more than 50 years old. At the time the machine was designed, the limited computing power available and the absence of 3D electromagnetic (EM) simulation codes, made the creation of a linac optimized for power efficiency almost impossible, so from this point of view, the ISIS linac is quite simple by today's standards. In this paper, we make a shunt impedance comparison study using the power consumption data collected from ISIS and the results obtained when simulating each of the four DTL tanks with 2D and 3D EM codes. The comparison will allow us to check the accuracy of our simulation codes and models and to assess their relative performance. It is particularly important to benchmark these codes against real data, in preparation for their use in the design of a proposed new linac, which will replace the currently aging ISIS injector. 

THP075  XBand Traveling Wave RF Deflector Structures  kicker, emittance, factory, electron  966 


Funding: Work supported by U.S. Department of Energy, contract DEAC0276SF00515 (SLAC) 

THP090  Marx Bank Technology for Accelerators and Colliders  highvoltage, controls, collider, diagnostics  1002 


Funding: U.S. Department of Energy SBIR Program 

THP098  RF Vector Control for Efficient FanOut Power Distribution  cavity, controls, linac, coupling  1018 


Funding: This work was supported by SNS through UTBattelle, LLC, under contract DEAC0500OR22725 for the U.S. DOE. 