Coherent radiation sources based on laser plasma accelerators

Jaroszynski, D.A. and Vieux, G. (2002) Coherent radiation sources based on laser plasma accelerators. American Institute of Physics Conference Proceedings, 647. pp. 902-913. ISSN 1551-7616 (http://dx.doi.org/10.1063/1.1524946)

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Abstract

Laser-driven plasma wakefield accelerators (LWFAs) based on table-top terawatt lasers have the potential of producing high brightness ultra-short electron bunches that are ideal for driving free-electron lasers (FELs). These sources are excellent candidates for reaching the x-ray spectral region. However, the creation of a compact radiation source based on this technology requires a number of difficult challenges to be met. Currently, LWFAs produce beams with excellent transverse emittance but very large energy spectra. To meet the requirement that the fractional energy spread should be less than the universal FEL gain parameter, , the electron bunch injected into the accelerator must occupy a small region of phase space. We will discuss a new project that has recently been set up in the UK to develop LWFA technology and apply to the creation of a compact FEL. To meet the stringent injection requirements, 10 MeV ultra-shot injection electron bunches, with durations a fraction of the plasma wake period, will be produced in a photoinjector. A fully ionized hydrogen filled capillary, with plasma densities up to 1019 cm-3, will have a dual function of acting as a preformed plasma waveguide for guiding the laser pulse while providing the medium for the LWFA. Table-top terawatt Ti:sapphire lasers will be utilized as drive lasers. As a demonstration of the utility of the compact accelerator, electron bunches from the LWFA will be used to create coherent electromagnetic radiation in a FEL. Progress on the development of the plasma capillary channel and diagnostic systems based on terahertz time domain spectroscopic techniques are presented. ©2002 American Institute of Physics