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.
Coherent electron beam density modulator for driving X-ray free electron lasers
Abstract We propose a new compact scheme for a Free Electron Laser with more coherent properties for the X-ray beam. Higher FEL performance would be achieved using a train of electron bunches initially accelerated in a linear accelerator. Similar to the RF klystron concept, we propose developing an X-ray FEL which consists of two parts: an X-ray self-seeding electron beam density modulator and an output set of undulators. A density modulator consists of a low-Q X-ray cavity and an undulator, which is placed between the cavity mirrors. We use this undulator as a very high gain amplifier, which compensates the amplitude loss due to monochromatic X-ray reflections from the mirrors. Following the X-ray cavity, the density modulated electron beam is separated from the X-ray beam and then enters the output set of undulators. The frequency spectrum of the final X-ray beam is determined mainly by the bandwidth of the reflected elements in the X-ray cavity.
DESIGN CONSIDERATIONS FOR THE 4GLS XUV-FEL
An XUV Free-ElectronLaseroperatinginthe photonenergy range 10-100eV is a key component of the proposed 4th Generation Light Source (4GLS) at Daresbury Laboratory in the UK. The current design proposal is an amplifier FEL seeded by a High Harmonic Generation (HHG) source. In this paper we present and discuss the considerations that led to the current design. We also present 3D simulation results that illustrate the potential radiation output characteristics.