| Paper | Title | Page |
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| TPAE016 | The Argonne Wakefield Accelerator Facility: Status and Recent Activities | 1485 |
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Funding: This work is supported by the U.S. Department of Energy, under contract No. W-31-109-ENG-38. The Argonne Wakefield Accelerator Facility (AWA) is dedicated to the study of electron beam physics and the development of accelerating structures based on electron beam driven wakefields. In order to carry out these studies, the facility employs a photocathode RF gun capable of generating electron beams with high bunch charges (up to 100 nC) and short bunch lengths. This high intensity beam is used to excite wakefields in the structures under investigation. The wakefield structures presently under development are dielectric loaded cylindrical waveguides with operating frequencies of 7.8 or 15.6 GHz. The facility is also used to investigate the generation and propagation of high brightness electron beams. Presently under investigation, is the use of photons with energies lower than the work function of the cathode surface (Schottky-enabled photoemission), aimed at generating electron beams with low thermal emittance. Novel electron beam diagnostics are also developed and tested at the facility. The AWA electron beam is also used in laboratory-based astrophysics experiments; namely, measurements of microwave Cherenkov radiation and fluorescence of air. We report on the current status of the facility and present recent results. |
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| TPAE018 | 34.272 GHz Multilayered Dielectric-Loaded Accelerating Structure | 1592 |
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| A scheme of multilayered structure design of 34.272 GHz with alternating dielectric of 38 and 9.7 is presented. The multilayer structure employs the Bragg Fiber concepts where the dielectric layers are used to create multiple reflections in order to confine the accelerating fields, thus greatly reducing the power loss of from external metal wall. The structure will operate at TM03 mode instead of normal TM01 mode. Numerical examples for the 2- and 4-layers 34.272 GHz multilayered structures are presented with detailed analysis of TM (acceleration) modes and HEM (parasitic) modes. We found that the power attenuation of the proposed structure can be lowered from ~ 20 dB/m for a single layer structure to ~ 6 dB/m for 2 -4 layered structure in at 34.272 GHz. We will also present a coupler design for the multilayered dielectric-loaded accelerating structure, which has capability of mode selection and high efficient RF transmission. | ||
| TOPA005 | Left-Handed Metamaterials Studies and their Application to Accelerator Physics | 458 |
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Funding: DOE grant NSF grant Recently, there has been a growing interest in applying artificial materials, known as Left-Handed Metamaterials (LHM), to accelerator physics. These materials have both negative permittivity and permeability and therefore possess several unusual properties: the index of refraction is negative and the direction of the group velocity is antiparallel to the direction of the phase velocity (along k). These properties lead to a reverse Cherenkov effect, which has potential beam diagnostic applications, in addition to accelerator applications. Several LHM devices with different configurations are being experimentally and theoretically studied at Argonne. In this paper, we describe permittivity and permeability retrieval techniques that we have developed and applied to these devices. We have also investigated the possibility of building a Cherenkov detector based on LHM and propose an experiment to observe the reverse radiation generated by an electron beam passing through a LHM. The potential advantage of a LHM detector is that the radiation in this case is emitted in the direction reversed to the direction of the beam, so it could be easier to get a clean measurement. |
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| WPAP034 | Positron Emulator for Commissioning ILC Positron Source | 2321 |
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Funding: U.S. DOE. It is apparent that the gamma-ray based positron source components including positron linac and damping rings for ILC can not be easily commissioned until the electron beam is fully conditioned at high energies (> 150 GeV). In this paper, we discuss a scheme that could use a short and energetic electron beam scattered through a set of carefully selected targets to simulate certain behaviors of the positron beam, such as beam emittance and energy spread. The basic idea is to make the phase space distribution of the scattered electron beam to reflect certain aspects of the positron beam distributions. Subsequently, the positron source elements such as capture optics, linacs and even damping ring could be effectively commissioned before ILC colliding electron beam is ready. The simulation results using EGS4 for beam scattering and PARMELA for beam dynamics are presented. |
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| TPAT058 | Calculation of Electron Beam Potential Energy from RF Photocathode Gun | 3441 |
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Funding: U.S. Department of Energy. In this paper, we consider the contribution of potential energy to beam dynamics as simulated by PARMELA at low energies (10 - 30MeV). We have developed a routine to calculate the potential energy of the relativistic electron beam using the static coulomb potential in the rest frame (first order approximation as in PARMELA). We found that the potential energy contribution to the beam dynamics could be very significant, particularly with high charge beams generated by an RF photocathode gun. Our results show that when the potential energy is counted correctly and added to the kinetic energy from PARMELA, the total energy is conserved. Simulation results of potential and kinetic energies for short beams (~1 mm) at various charges (1 - 100 nC) generated by a high current RF photocathode gun are presented. |
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| RPPP003 | Proposal of the Next Incarnation of Accelerator Test Facility at KEK for the International Linear Collider | 874 |
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| The realization of the International Linear Collider (ILC) will require the ability to create and reliably maintain nanometer size beams. The ATF damping ring is the unique facility where ILC emittancies are possible. In this paper we present and evaluate the proposal to create a final focus facility at the ATF which, using compact final focus optics and an ILC-like bunch train, would be capable of achieving 35nm beam size. Such a facility would enable the development of beam diagnostics and tuning methods, as well as the training of young accelerator physicists. |