13-03-2009 Colloquium by Klaus-Jochen Boller

4 maart 2009

Colloquium by Klaus-Jochen Boller, Universiteit Twente

15:30h at Nikhef in room H331

Laser Wake Field Acceleration of Electrons with External Bunch Injection

A drawback of conventional particle accelerators is that the accelerating electric field is limited to the range of tens of MeV/m. This requires Kilometer-sized facilities when particles with kinetic energies of many GeV are to be provided. A potential alternative to this approach is acceleration in laser driven plasma waves, so-called laser wake field acceleration (LWFA). There, the 1000-time higher fields bear the possibility to reduce the size of accelerators by a similar factor. Experimentally, the required fields can be generated by focusing multi-TW laser pulses with peak intensities around 1018 W/cm2 into plasma, which is based on charge separation by the ponderomotive force. The central problem, however, which is also named the injection problem in LWFA, is to generate, pre-accelerate and inject ultra-short (fs duration), micron-sized electron bunches which is required for acceleration with a low relative energy spread. I will report on our efforts to design and set up an experiment that might demonstrate a novel solution to the injection problem. The scheme is based on external injection of the initially much larger and longer bunches from a standard microwave accelerator, but where the bunches are trapped and spatio-temporally compressed in the plasma wave.