Prof. Dino Jaroszynski (University of Strathclyde, Glasgow, UK), Laser-driven accelerators and radiation sources: a new paradigm

Wednesday 14 Apr 2010, 10:00 → 11:00 Europe/Bucharest

In this talk we will present progress towards producing an ultra-compact laser driven plasma wakefield accelerator and applying it as an ultra-short pulse radiation source. Strathclyde has been leading the way in developing and applying these compact sources, through the Advanced Laser Plasma High-energy Accelerators towards X-rays (ALPHA-X). We will discuss how the state-of-the-art prior to ALPHA-X, where electron beams were produced with 100% energy spreads, has been completely transformed by pioneering developments by the ALPHA-X team, culminating in routinely producing very high quality electron beams with energies between 50 MeV and 1 GeV. The wakefield accelerator at Strathclyde produces high brightness electron beams with such high quality that it is now making feasible a compact university laboratory sized free-electron laser or hard X-ray source that could transform the way science is done. Apart from the excellent measured beam properties: energy spread less than 0.4% at 100 MeV, emittance less than 1.5 pi mm mrad and bunch duration less than 10 femtoseconds, giving peak currents of 1 - 5 kA, there are other opportunities to exploit the electron beams while still in the plasma. The very large transverse forces in the plasma channel produced by the laser pulse cause oscillation of the electrons resulting in the emission of brilliant gamma ray pulses with durations less than 10 femtoseconds. We will present recent experimental results from the ALPHA-X project which show intense gamma rays are produced with such intensities and photon energies that they pass through 20 cm of lead. These results open up the possibility of imaging very dense matter and studying nuclear processes directly in the time domain on a femtosecond time scale. However, to demonstrate the immediate applicability of such a hard X-ray source we have demonstrated phase-contrast imaging of a weakly absorbing object, which indicates the usefulness of the source for medical imaging of tissue. The talk will concentrate on the new opportunities arising from this paradigm shift, replacing the accelerating forces of microwave cavities by forces in plasma due to charge separation to accelerate particles and generate radiation on a footprint that is one thousand times smaller. The development of the laser-plasma wakefield accelerator could be heralding a revolution in the way science is done, but in the near term - many new and exciting results are being produced. These new opportunities have led to the creation of the Scottish Centre for the Application of Plasma-based Accelerators (SCAPA), which brings together scientists from the Scottish Universities Physics Alliance (SUPA) and further afield.