A 3D model of the 4GLS VUV-FEL conceptual design including improved modelling of the optical cavity
The Conceptual Design Report for the 4th Generation Light Source (4GLS) at Daresbury Laboratory in the UK was published in Spring 2006. The proposal includes a low-Q cavity (also called a regenerative amplifier) FEL to generate variably-polarised, temporally-coherent radiation in the photon energy range 3-10eV. A new simulation code has been developed that incorporates the 3D FEL code Genesis 1.3 and which simulates in 3D the optical components and radiation propagation within the non-amplifying sections of an optical cavity*. This code is used to estimate the optimum low-Q cavity design and characterise the output from the 4GLS VUV-FEL.
4GLS and the Energy Recovery Linac Prototype Project at Daresbury Laboratory
4GLS is a novel next generation proposal for a UK national light source to be sited at Daresbury Laboratory, based on a superconducting energy recovery linac (ERL) with both high average current photon sources (undulators and bending magnets) and high peak current free electron lasers. Key features are a high gain, seeded FEL amplifier to generate XUV radiation and the prospect of advanced research arising from unique combinations of sources with femtosecond pulse structure. An R&D programme is addressing the challenging accelerator technology involved and a major part of this is a 35 MeV demonstrator, the ERL Prototype (ERLP) currently under construction. The 4GLS design activities are summarised, the ERLP described in detail and the 4GLS project status and plans explained.
SPACE CHARGE EFFECTS FOR THE ERL PROTOTYPE AT DARESBURY LABORATORY
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 transfer line. This is done in two ways. The first is based on an analytic formula derived via the envelope equations and a Kapchinsky-Vladimirsky (KV) distribution. This formula gives an appropriate estimate of the space charge effects in the case that no quadrupoles or dipoles are present in the transfer line. The second estimate is given by the multi-particle tracking code ASTRA for the whole transfer line both with and without quadrupoles. The methods are compared and are found to be in good agreement. Typical examples of beam transfer lines are given together with specific calculations for the ERLP.