Paper  Title  Other Keywords  Page 

MOP067  High Gradient Excitation and RF Power Generation Using Dielectric Loaded Wakefield Structures  electron, gun, klystron, laser  232 


Funding: Work supported by the U.S. Department of Energy under contract No. DEAC0206CH11357. 

MOP068  Trains of SubPicosecond Electron Bunches for HighGradient Plasma Wakefield Acceleration  plasma, electron, emittance, simulation  235 


Funding: Work Supported by US Department of Energy *P. Muggli et al., to appear in Phys. Rev. Lett. (2008). 

MOP087  Status of Longitudinal Beam Dynamics Studies in CTF3  simulation, electron, spacecharge, cavity  278 


The aim of the CLIC Test Facility CTF3, built at CERN by an international collaboration, is to address the main feasibility issues of the CLIC electronpositron linear collider technology by 2010. One keyissue studied in CTF3 is the generation of the very high current drive beam, used in CLIC as the rf power source. It is particularly important to simulate and control the drive beam longitudinal dynamics in the drive beam generation complex, since it directly affects the efficiency and stability of the rf power production process. In this paper we describe the ongoing effort in modelling the longitudinal evolution of the CTF3 drive beam and compare the simulations with experimental results. 

MOP089  Beam Dynamics and Wakefield Simulations for High Gradient ILC Linacs  cavity, simulation, linac, emittance  284 


Higher order modes (HOMs) are simulated with finite element and finite difference computer codes for the ILC superconducting cavities currently under investigation for the ILC. In particular, HOMs in KEK's Ichiro type of cavity and Cornel University's Reentrant design are focussed on in this work. The aim, at these Universities and laboratories, is to achieve an accelerating gradient in excess of 50 MV/m in 9cell superconducting cavities whilst maintaining a high quality and stable electron beam. At these high gradients, electrical breakdown is an important cause for concern and the wakefields excited by the energetic electron beams are also potentially damaging to the beam's emittance. Here we restrict the analysis to performing detailed simulations, on emittance dilution due to beams initially injected with realistic offsets from the electrical centre of the cavities and due to statistical misalignments of the cavities. We take advantage of the latest beam dynamics codes in order to perform these simulations. 

MOP104  Parallel 3D Finite Element ParticleInCell Code for HighFidelity RF Gun Simulations  simulation, gun, spacecharge, emittance  317 


Funding: Work supported by DOE contract DEAC0276SF00515. 

MOP105  Beam Dynamics and Wakefield Simulations for the CLIC Main Linacs  emittance, cavity, damping, linac  320 


The CLIC linear collider aims at accelerating multiple bunches of electrons and positrons and colliding them at a center of mass energy of 3 TeV. These bunches are accelerated through Xband linacs operating at an accelerating frequency of 12 GHz. Each beam readily excites wakefields in the accelerating cavities of each linac. The transverse components of the wakefields, if left unchecked, can dilute the beam emittance. The present CLIC design relies on heavy damping of these wakefields in order to ameliorate the effects of the wakefields on the beam emittance. Here we present initial results on simulations of the longrange wakefields in these structures and on beam dynamics simulations. In particular, detailed simulations are performed, on emittance dilution due to beams initially injected with realistic offsets from the electrical centre of the cavities and due to statistical misalignments of the cavities. 

TU302  Control, Stability and Staging in Laser Wakefield Accelerators  laser, controls, linac, plasma  379 


Laser driven plasma wakefields have recently accelerated electron beams with quasimonoenergetic energy distributions and with gradients of ~100 GV/m. Stabilization and optimization of beam quality are now essential. Recent LBNL experiments have demonstrated control of self trapping, resulting in reproducible bunches at 0.5 GeV. Further optimization has been demonstrated using plasma density gradients to control trapping, producing beams with very low absolute momentum spread at low energies. Simulations indicate that use of these beams as an injector greatly improves accelerator performance and experiments are now underway to demonstrate such staging, which will be a crucial technology for laser driven linacs. This talk will cover recent progress in LWFAs to obtain more reproducible, higher quality beams and also cover staging prospects for high energy laser linacs. 



TUP050  Design and Optimization of Electron Bunch Acceleration and Compression  electron, linac, acceleration, cavity  512 


Funding: The work of PE and JW was supported by the US Department of Energy under contract DEAC0276SF00515. The work of RAB and KJK was supported by National Science Foundation Award No. DMR0537588. 

TUP055  Optimum Frequency and Gradient for the CLIC Main Linac Accelerating Structure  linac, luminosity, collider, acceleratinggradient  527 


Recently the CLIC study has changed the operating frequency and accelerating gradient of the main linac from 30 GHz and 150 MV/m to 12 GHz and 100 MV/m, respectively. This major change of parameters has been driven by the results from a novel main linac optimization procedure. The procedure allows simultaneous optimization of operating frequency, accelerating gradient, and many other parameters of CLIC main linac. It takes into account both beam dynamics (BD) and high power rf constraints. BD constraints are related to emittance growth due to short and longrange transverse wakefields. Rf constraints are related to rf breakdown and pulsed surface heating of the accelerating structure. The optimization figure of merit includes the power efficiency, measured as a ratio of luminosity to the input power as well as a quantity proportional to investment cost. 

TUP057  Design and Fabrication of CLIC Test Structures  damping, HOM, acceleratinggradient, impedance  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. 

TUP107  Longitudinal Beam Diagnostics for the ILC Injectors and Bunch Compressors  diagnostics, luminosity, emittance, bunching  655 


Funding: Work supported by US. Department of Energy, under Contract No. DEFG0206ER41435 with Northern Illinois University. 

THP038  A New SRF Cavity Shape with Minimized Surface Electric and Magnetic Fields for the ILC  cavity, HOM, dipole, coupling  867 


Funding: Work supported by DOE contract DEAC0276SF00515. 



THP074  A New Accelerator Structure Concept: the Zipper Structure  coupling, HOM, damping, resonance  963 


Funding: Work supported by the U.S. Department of Energy under contract DEAC0276SF00515. 