Observation of relativistic and charge-displacement self-channeling of intense subpicosecond ultraviolet (248 nm) radiation in plasmas

Abstract

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Stable relativistic/charge-displacement channels in ultrahigh power density (≈10 21 W/cm 3 ) plasmas

“…Initial experimental studies (2)(3)(4)(5), conducted close to the threshold condition of the channeling phenomenon (6)(7)(8)(9)(10)(11)(12)(13)(14)(15), have furnished evidence supporting this conclusion. Measurements of the spatial properties of the propagation, using both x-ray (4) and Thomson (16,17) images, have clearly established the formation of long channels of the form shown in Fig.…”

“…2. The azimuthally perturbed Gaussian amplitude distribution has the form U0(r, ) ϭ I0 1/2 exp(Ϫ0.5(r͞ r0) 2 ) ϫ (1 ϩ (r͞r0) 4 ⌺q cos(q)). The distribution contains a weak azimuthal perturbation characterized by q ϭ 0.03, q ϭ 1-4, and ␦int ϭ max ͉I0(r, 1) Ϫ I0(r, 2)͉͞I0 ϭ 0.21.…”

Plasma channeling by multiple short-pulse lasers

“…The channeling or boring of an intense laser pulse in plasma and ion acceleration have been investigated extensively (Wilks et al, 1992;Borisov et al, 1992;Tabak et al, 1994;Zepf et al, 1996;Borghesi et al, 1997Borghesi et al, , 2002Borghesi et al, , 2007Fuchs et al, 1998;Vshivkov et al, 1998;Tanaka et al, 2000;Willi et al, 2001;Kodama et al, 2001;Najmudin et al, 2003;Hoffmann et al 2005;Flippo et al 2007;Laska et al 2007;Lei et al, 2007). In the relativistic-intensity regime, the relativistic ponderomotive force, which is proportional to the gradient of the laser intensity, dominates the laserplasma interaction (f p / ÀrI).…”

Observation of the plasma channel dynamics and Coulomb explosion in the interaction of a high-intensity laser pulse with a He gas jet

“…1 The critical power for relativistic self-focusing P c ϭ17n c /n e GW ͑where n e is the electron density and n c is the critical density͒ corresponds under our conditions to 280 GW, which is more than 10 times lower than the actual laser power. Therefore we speculate that a substantial part of the laser power is trapped in a narrow channel near the laser axis.…”

“…Guiding of intense laser pulses in underdense plasmas due to the relativistic self-focusing was first reported in Ref. 1 and then studied in detail in Refs. 2-6.…”