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Title |
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| MOPCH069 |
Lattice Design for the Fourth Generation Light Source at Daresbury Laboratory
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184 |
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- B.D. Muratori, M.A. Bowler, H.L. Owen, S.L. Smith
CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
- S.V. Miginsky
BINP SB RAS, Novosibirsk
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The proposed Fourth Generation Light Source (4GLS) has three electron transport paths, an energy recovery loop containing the main linac, IDs and a VUV-FEL, a separate branch after the main linac for an XUV-FEL and a transport path for an IR-FEL. The first two present major challenges in lattice design. The energy recovery loop will be fed by a high average current gun, with bunches of charge of about 80 pC. High charge (1nC) bunches from a high brightness gun will be accelerated prior to the main linac and split into the XUV-FEL branch using energy separation after the main linac. We present a lattice design and results from numerical modelling of the electron bunch transport. The requirements of the machine are short bunches, a small emittance for both branches and an overall topology which gives a reasonable dimension for the building. Different transport and compression schemes were assessed to meet these requirements whilst balancing the disruptive effects of longitudinal and transverse space charge, CSR, wakefields and BBU. Investigations into all of these instabilities are summarized together with other transport issues and the resulting requirements on all IDs.
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| TUPCH039 |
A Phase Space Tomography Diagnostic for Pitz
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1091 |
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- D.J. Holder, B.D. Muratori
CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
- F.E. Hannon
Jefferson Lab, Newport News, Virginia
- S. Khodyachykh, A. Oppelt
DESY Zeuthen, Zeuthen
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The Photo Injector Test Facility at DESY in Zeuthen (PITZ) is a European collaboration developing RF photocathode electron guns for light source and linear collider projects. As part of the collaborative work being partially funded by the EU's FP6 programme, CCLRC Daresbury Laboratory and DESY are designing and building a phase space tomography diagnostic based on a set of multiple quadrupoles and view screens. In order to measure the beam emittance, four screens with intermediate quadrupole doublets will be used. The equipment will be installed and tested at PITZ as part of the facility upgrade presently ongoing. Following simulations of the gun using the ASTRA code at a range of energies, simulations of the electron beam parameters through the matching and tomography sections must be undertaken in order to specify the optimum arrangement of magnets and screens.
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| THPCH040 |
Linac Focusing and Beam Break Up for 4GLS
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2871 |
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- E. Wooldridge, B.D. Muratori
CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
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As part of the design for 4GLS the linac focusing and its effect on the beam break up (BBU) threshold have been studied. The choice of graded gradient focusing scheme is discussed and initial models of the focusing, using a triplet of quadrupoles between each of the modules within the linac, are presented. The quadrupoles were set-up in a defocusing - focusing - defocusing format with strengths of -1/2k, k, -1/2k. Using these models the BBU threshold was computed using available codes assuming a 9-cell TESLA cavity within the linac and a 7-cell design with HOM dampers. A sweep of the magnet strength with respect to the BBU threshold showed that there is an optimum setting.
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