Ultrahigh-brightness KrF laser system for fast ignition studies

Multiple filamentation of supercritical UV laser beam in atmospheric air

“…That was a reason why a direct USP amplification at the UV wavelength k = 248 nm was first considered to achieve a highpeak-power USP (see [17] and references therein). Although peak power of $10 TW obtained at large-scale e-beam-pumped KrF facilities exceeds by 5 orders of magnitude the critical power P cr % 0.1 GW for k = 248 nm, no evidences of the UV laser beam filamentation, as well as of nonlinear absorption or phase-modulation were reported in those experiments [6][7][8][9]. On the contrary, in our experiments at GARPUN-MTW Ti:Sapphire/KrF laser facility a multiple filamentation was clearly observed for output UV radiation with a peak power P $1 TW and sub-ps pulse length [18][19][20][21].…”

“…A 390-fsec USP with a peak power of 4 TW was obtained at slightly smaller facility [9] while the shortest UV USP ever achieved with a discharge-pumped KrF amplifier was 60-fs long [10]. In addition, short-wavelength KrF lasers have better focusing capability with a focal spot area scaling as S / k 2 , and peak USP intensities as high as 10 20 W/cm 2 were announced [6,7,11].…”

“…For such targets UV radiation of KrF laser has evident benefits in comparison with the IR radiation of solid-state lasers because of higher plasma critical density n ecr , which scales with the laser wavelength k as n ecr / k À2 . About 10-TW peak powers were demonstrated earlier for a few ps-length UV USP at the biggest Super-Sprite and Super-ASHURA KrF laser systems with 60-cm-aperture of e-beam-pumped final amplifier [6][7][8]. A 390-fsec USP with a peak power of 4 TW was obtained at slightly smaller facility [9] while the shortest UV USP ever achieved with a discharge-pumped KrF amplifier was 60-fs long [10].…”

Understanding laser beam brightness: A review and new prospective in material processing

“…Shaw et al [83] reported that fast ignition can be achieved with the use of a high brightness KrF laser system with a low wavelength (268 nm). The paper also reported that femtosecond pulses could obtain a significantly high brightness value and this is rightly so due to the low wavelength of the KrF laser which could generally exhibit a high brightness value.…”

Progress on high power excimer laser in NINT

“…Rare gas halide excimer lasers are widely concerned as powerful ultra-violet sources [1][2][3][4][5] . Excimer laser has outstanding features including short wavelength, good uniform illumination, focal beam zooming and rep-rate operation, which leads to many advantages over glass lasers in target physics such as high coupling efficiency, high threshold of plasma parametric instabilities and minimal laser imprinting disturbance [6][7] .…”