| Paper |
Title |
Page |
| MOPKF056 |
Injector Design for the 4GLS Energy Recovery Linac Prototype
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437 |
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- C. Gerth, F.E. Hannon
CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
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Daresbury Laboratory has been given funding for the construction of an Energy Recovery Linac Prototype (ERLP) that operates at a target electron beam energy of 35 MeV and drives an IR oscillator FEL. The ERLP serves as a test-bed for the study of beam dynamics and accelerator technology important for the design and construction of the proposed 4th Generation Light Source (4GLS). A key component of the ERLP is a high-brightness injector. The injector consists of a DC photocathode gun, which is currently being built at Daresbury Laboratory and based on the design of the gun for the IR demonstrator FEL at Thomas Jefferson National Accelerator Facility. The gun section is followed by a conventional buncher cavity, a super-conducting booster and a transfer line to the main linac. In this paper, the design of the ERLP injector is discussed. The performance of the injector has been studied using the particle tracking code ASTRA.
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| MOPKF060 |
Space Charge Effects for the ERL Prototype at Daresbury Laboratory
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446 |
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- B.D. Muratori, C. Gerth
CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
- N. Vinokurov
BINP SB RAS, Novosibirsk
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Daresbury Laboratory is currently building an Energy Recovery Linac Prototype (ERLP) that will operate at a beam energy of 35 MeV. In this paper we examine the Space Charge effects on the beam dynamics in the ERLP injector line. This is done in two distinct ways. The first is based on an analytic formula derived by Vinokurov through the envelope equations and a Kapchinsky-Vladimirsky (KV) distribution. This formula gives a rough estimate of the space charge effects in the case that no quadrupoles or dipoles are present in the injector line. The second estimate is given by the multi-particle tracking code ASTRA for the whole injector line both with and without quadrupoles. Both methods are compared and are found to be in good agreement. Typical examples of injector lines are given together with specific calculations for the ERLP.
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| MOPKF067 |
Comparison of Different Buncher Cavity Designs for the 4GLS ERLP
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467 |
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- E. Wooldridge, C.D. Beard, C. Gerth
CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
- A. Buechner
FZR/FWFE, Dresden
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A DC photocathode gun is part of the injector of the Energy Recovery Linac Prototype (ERLP) currently built at Daresbury Laboratory. A buncher is required for the ERLP to decrease the bunch length off the gun. Three different single-cell cavity designs were investigated: The Cornell buncher, the Elbe Buncher and an EU cavity without Higher Order Mode (HOM) dampers. The properties of these cavities were studied with the computer codes CST's Microwave Studio and ASTRA. The fundamental frequency and field pattern was investigated in Microwave Studio. The EU cavity had to be scaled from 500MHz as the required frequency for the buncher is 1.3GHz. As the anticipated kinetic energy of the electron beam after the gun is about 350keV a particle tracking code including the space charge forces is mandatory to study the effect of the different buncher cavity designs on the beam dynamics. The particle tracking code ASTRA was used to study the performance of the bunchers for a variety of beam parameters. From these investigations it was found that the three bunchers produce very similar effects on the particle bunch.
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| THPLT044 |
Measurement of the Transverse Coherence of the TTF Free Electron Laser
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2577 |
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- R. Ischebeck, M. Tonutti
RWTH, Aachen
- J. Feldhaus, E. Saldin, E. Schneidmiller, K. Tiedtke, R. Treusch
DESY, Hamburg
- C. Gerth
CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
- P. Schmüser
Uni HH, Hamburg
- M.V. Yurkov
JINR, Dubna, Moscow Region
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The transverse coherence is important for many applications of a free electron laser (FEL). It depends on the inner structure of the electron bunch in the undulator, which is difficult to measure. It is therefore essential to determine the coherence properties of the FEL radiation directly. The coherence of the vacuum ultraviolet FEL at the TESLA Test Facility has been measured by recording the diffraction pattern of a double slit and measuring the visibility of the interference fringes. The experimental near field diffraction pattern is compared with a numerical model, taking into account the formation of the FEL radiation, the Fresnel diffraction in the near field zone and effects of the experimental set-up. Diffraction patterns have been recorded at various undulator lengths to measure the evolution of the transverse coherence along the undulator. This is compared to the expected evolution of the transverse radiation modes.
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