Background:
Existing accelerators (linacs, synchrotrons, cyclotrons) apply externally generated RF-potentials to accelerate and bunch charged particles. To reach TeV energies, these accelerators have sizes of kilometers or miles.
High-power lasers open a new path toward compact accelerators because the driving electromagnetic fields are self-generated by the displacement current in the focal spot.
Laser-driven acceleration schemes are based on the acceleration of particles in the strong quasistatic electric fields or the fast-moving electromagnetic fields generated by the interaction of ultra-intense laser pulses with matter.
The interaction mechanisms involved include:
(a) Target Normal Sheath Acceleration (TNSA): in this scheme, a high-intensity laser pulse is focused onto the front side of a thin foil. At the focal point, electrons are expelled normal to the target's surface, creating an electrostatic field (sheath) that accelerates ions from the target's rear side.
(b) Laser Wakefield Acceleration (LWFA): here, the laser pulse propagates through a plasma channel or a gas jet. The ponderomotive force of the laser pulse expels electrons from the center of the interaction region, leading to the formation of a wakefield. The electric fields in the wake structure can then accelerate trailing electrons or positrons.
(c) Radiation Pressure Acceleration (RPA): in RPA, a high-energy photon transfers its momentum to a charged particle. This scheme can accelerate electrons to ultrahigh energies by exploiting the Breit-Wheeler process, in which a gamma-ray photon converts into an electron-positron pair in the presence of a strong electromagnetic field.
(d) Beam-Driven Plasma Wakefield Acceleration: In this scheme, a charged particle beam, such as a proton beam generated from a conventional accelerator, drives a plasma wakefield that can accelerate other charged particles.
Particle beam acceleration using lasers is a rapidly growing field of research, with the potential for significant advancements in particle physics, medical applications, and industrial settings.
