RELATIVISTIC SELF-FOCUSING OF AN ULTRA-INTENSE LASER-PULSE IN A PLASMA

New compact multiterawatt lasers allow us to study the relativistic re gime of laser-plasma interaction. The propagation of a multiterawatt s ubpicosecond laser pulse in a plasma has been investigated theoretical ly and experimentally. A 10 TW laser pulse at a 1064 nm wavelength has been focused in a hydrogen gas jet. Thomson scattering observations s how that a relativistic self-focusing and channeling occur when the la ser power exceeds a critical value predicted by theory. The amount of enhancement in self-focused intensity exceeds one order of magnitude. The laser pulse propagates through the plasma over a distance much lar ger than the Rayleigh length determined by vacuum diffraction.