Beam Transport of Ultra-Short Electron Bunches

ABSTRACT: Focussing of ultra-short electron bunches from a wakefield accelerator into an undulator requires particular attention to be paid to the emittance, electron bunch duration and energy spread. We present a design of a focussing system for the ALPHA-X transport section, which consists of a triplet of permanent magnet quadrupoles. The design has been carried out using the GPT (General Particle Tracer) code [1], which considers the space charge effects and allows us to obtain a realistic estimate of the electron beam properties inside the undulator and therefore the properties of synchrotron emission and self-amplified spontaneous free-electron laser action. The first design The primary transport section is the segment between the end of the plasma channel and the start of the undulator. This section transports electron bunches produced by a plasma wakefield accelerator usually using magnetic devices. A synchrotron radiation source or free-electron laser requires the electron bunches to be focused into an undulator for a wide range of energies. In particular, the energies expected range is from 50MeV to 1GeV. The primary transport section of the ALPHA-X beam line has been modeled using th