| Paper | Title | Page |
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| TUPMN020 | Velocity Bunching at the European XFEL | 959 |
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| This paper explores the possibility to employ velocity bunching in the first RF module of the European XFEL to increase the peak current at the injector exit. The current increase will reduce the total longitudinal bunch compression factor and loosen rf jitter tolerances by the same amount. The relation between rf tolerances and micro-bunching instability gain is discussed and the injector optimization for cases of velocity bunching to 100A and 200A peak current are presented in detail. Finally, plans for velocity bunching experiments at the FLASH facility (Free Electron Laser in Hamburg) are laid out. | ||
| TUPMS064 | RF Gun Optimization Study | 1326 |
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Funding: Authored by Jefferson Science Associates, LLC under U. S. DOE Contract No. DE-AC05-06OR23177.
Injector gun design is an iterative process where the designer optimizes a few nonlinearly interdependent beam parameters to achieve the required beam quality for a particle accelerator. Few tools exist to automate the optimization process and thoroughly explore the parameter space. The challenging beam requirements of new accelerator applications such as light sources and electron cooling devices drive the development of RF and SRF photo injectors. RF and SRF gun design is further complicated because the bunches are space charge dominated and require additional emittance compensation. A genetic algorithm has been successfully used to optimize DC photo injector designs for Cornell* and Jefferson Lab**, and we propose studying how the genetic algorithm techniques can be applied to the design of RF and SRF gun injectors. In this paper, we report on the initial phase of the study where we model and optimize gun designs that have been benchmarked with beam measurements and simulation.
* I. Bazarov, et al., "Multivariate Optimization of a High Brightness DC Gun Photoinjector", PRST-AB 2005.** F. Hannon, et al., "Simulation and Optimisation of a 100 mA DC Photoinjector", EPAC 2006. |
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| THPMN025 | High QE Photocathodes Performance during Operation at FLASH/PITZ Photoinjectors | 2763 |
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Funding: Work supported by the European Community, contract number RII3-CT-2004-506008 The FLASH (DESY-Hamburg) and PITZ (DESY-Zeuthen) photoinjectors routinely use high quantum efficiency (QE) photocathodes produced at LASA (INFN-Milano), since 1998. To further understand the photocathode behavior during beam operation, photocathode QE measurements have been performed at different operating conditions in both RF photoinjectors. The analysis of these measurements will be used to improve the photocathode preparation procedures and to deeper understand the photocathode properties, whose final goal would be the further increase of their lifetime and beam quality preservation during the RF gun operations. |
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| TUPMN026 | Conditioning of a New Gun Cavity Towards 60 MV/m at PITZ | 971 |
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Funding: This work has partly been supported by the European Community, contracts RII3-CT-2004-506008 and 011935, and by the 'Impuls- und Vernetzungsfonds' of the Helmholtz Association, contract VH-FZ-005. Beginning 2007, a new gun cavity will be installed at the photo injector test facility at DESY in Zeuthen (PITZ). It will be conditioned towards gradients as high as 60 MV/m. This gradient is required for the operation of the European XFEL. Results from the conditioning for high peak power and high duty cycle will be reported. |
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| FRPMN017 | Beam Position Monitor Calibration at the FLASH Linac at DESY | 3937 |
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| In the FLASH (Free electron LASer in Hamburg) facility at DESY more than 60 beam position monitors (BPM) with single bunch resolution are currently installed, and more are planned for future installation. Their calibration has been initially made by measuring each electronics board in the RF laboratory. However the ultimate calibration of each monitor is made by measuring its response to beam movement. This is a time-consuming procedure depending on the availability and accuracy of other components of the machine such as corrector magnets. On the other hand it has the advantage of getting in one measurement the answer of the monitor with all its components and of being independent of the monitor type. The calibration procedure and particularities for various types of BPMs in various parts of the linac will be discussed. A procedure based on the response matrices is also now under study. This would significantly speed up the calibration procedure, which is particularly important in larger accelerators such as the European XFEL (X-ray Free Electron Laser), to be built at DESY. | ||
| FRPMN023 | New Beam Diagnostic Developments at the Photo-Injector Test Facility PITZ | 3967 |
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Funding: This work has partly been supported by the European Community, contracts RII3-CT-2004-506008 and 011935, and by the "Impuls- und Vernetzungsfonds" of the Helmholtz Association, contract VH-FZ-005. The Photo-Injector Test Facility at DESY in Zeuthen (PITZ) is an electron accelerator which was built to develop and optimize high brightness electron sources suitable for SASE FEL operation. Currently, in parallel to the operation of the existing setup, a large extension of the facility and its research program is ongoing. The beam line which has a present length of about 13 meters will be extended up to about 21 meters within the next two years. Many additional diagnostics components will be added to the present layout. Two high-energy dispersive arms, an RF deflecting cavity and a phase space tomography module will extend the existing diagnostic system of the photo injector and will contribute to the full characterization of new electron sources. We will report on the latest developments of the beam diagnostics at PITZ. |