The laser wakefield accelerator (LWFA) offers the possibility of reducing the size of accelerators by three orders of magnitude, while simultaneously reducing the bunch duration to femtoseconds. The high peak currents possible from LWFAs make them suitable as drivers of radiation sources such as the free-electron laser (FEL). A compact X ray FEL would have a large impact on the way science is done by making powerful tools available to universities and research establishments.
Recent progress will be presented of the Advanced Laser Plasma High-energy Accelerators towards X-rays (ALPHA-X) project where a compact coherent radiation source based on the LWFA is being developed. A high power laser pulse (900 mJ, 35 fs) is focused into a 2 mm long gas jet. Electrons from the plasma are self-injected into the accelerating potential of the plasma density wake behind the laser pulse. Measurements have been made of the electron beam properties, i.e. charge, energy spread, emittance and bunch length, and these are compared with predictions from OSIRIS PIC simulations and reduced models. It is shown that the LWFA characteristics are suitable for driving a FEL. Results of electrons generated in a 40 mm long capillary discharge waveguide are also presented.
