PARTICLE ACCELERATION IN PLASMAS

Abstract

Welcome to this meeting in Taipei. I am very happy to see many of world's active leading researchers in this field are gathering here. This is indeed a time of great excitement in the plasma acceleration. In April, three articles appeared in Nature demonstrating the acceleration of nearly mono-energetic electrons by short pulsed lasers when they reached the intensity threshold for relativistic self-focusing. In May, the acceleration of SLAC 28.5 GeV electron beam by the beam driven wakefield in plasma was published in PRL. It is fitting in this centennial year of publication of Einstein's four papers that relativistic laser plasma interaction becomes a hot topic and relativistic plasma physics made a big stride. In this talk, I would like to give a personal perspective of particle acceleration in plasmas and survey some of the outstanding recent results. Then I would like to pose some questions and show some of the preliminary work by my colleagues here notably that of Prof. S. H. Chen in simulation. Our universe now is believed to be dominated by Dark Matter and Dark Energy. But the visible universe is dominantly in the plasma state and plasma is a very effective accelerating medium. Recent advances in high energy astrophysics have demonstrated amply the explosive and efficient particle acceleration by plasma processes — Radio jets, X ray sources, pulsars, and Gamma ray bursts. The particle acceleration is most clearly seen in the acceleration of Cosmic Rays. Eugene Parker once remarked the fact the Nature seems to be so unfair that it gives most of the energies to just a few electrons — so plasma as an accelerating medium can be very capitalistic. The Cosmic Ray spectrum is very rich in different characteristic slopes