Laser-Driven Particle Acceleration
Conventional charged particle accelerators are reaching their limit in size, cost, and accelerated particle energy. This talk will cover the various physical mechanisms involved in laser-driven particle acceleration, a leading concept for compact next generation devices. The ultra-high electric fields ( > TV/m) associated with ultrashort, intense laser pulses can accelerate electrons (or ions) to high energies in extremely short distances (~ mm). In the laser wakefield accelerator, a laser pulse propagates in a plasma and the ponderomotive forces associated with the pulse envelop induce large amplitude plasma waves which trap and accelerate electrons. To achieve high energies ( > GeV) it is necessary to optically guide the laser pulse over long distances, i.e., many Rayleigh ranges, in a plasma channel. The physical processes involved in laser driven plasma accelerators include optical guiding, relativistic effects, optical/plasma instabilities, electron dephasing, and group velocity dispersion. For example, to postpone dephasing (electrons overtaking the plasma wave), a tapered plasma density channel can be employed. In addition to their use in high-energy physics research, high energy electrons can be used to generate radiation from the UV to the gamma ray regime. The interaction of ultrashort intense laser pulses with matter can also generate high energy ions ( > 100 MeV). The U. of Md. laser driven acceleration program will be discussed.