Pumping of the GARPUN wide-aperture excimer laser by counterpropagating electron beams

Arlantsev, S V; Grigor'yants, E A; Vadkovskii, A D; Зворыкин, В. Д.; Metreveli, G. E.

doi:10.1070/qe1994v024n03abeh000070

Cited by 5 publications

(3 citation statements)

References 2 publications

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“…In our previous experiments e-beam pinching took place without magnetic field. This effect would introduce additional losses and scattering of electrons 18,19 effect is clearly demonstrated in Fig. 10, where the energy fluence of scattered electrons at 8.5-cm distance from e-beam boundary was much higher without magnetic field than in opposite case.…”

Section: Distribution Of Scattered Electrons In Laser Chambermentioning

confidence: 86%

“…The layout ofthese experiments is shown schematically in Fig.2. The "GARPUN" module 18, 19 has a laser chamber (1) with dimensions 19 x 22 x 140 cm and output aperture 16 x 18 cm. Two counter-propagating e-beams of the area 12 X100 cm and with current density 50 j2 were coupled into the chamber from opposite sides throughout vacuum-tight 2O-.tm thickness Ti or 50-jim Al-Be foils, which separated the working gas in a chamber from the vacuum diodes (2).…”

Section: Laser Facilities and Experimental Proceduresmentioning

confidence: 99%

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<title>Electron beam transport and foil stability in high-energy e-beam-pumped KrF lasers</title>

et al. 2001

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There are several key engineering and physical issues for the development of Krypton Fluoride driver for Inertial Fusion Energy Program. In the frame of this Program we have performed experiments with e-beam-pumped KrF laser installation GARPUN on the transportation of relativistic e-beams through Aluminum-Beryllium and Titanium foils and compared them with Monte Carlo numerical calculations. It was shown that 5O-.tm thickness Al-Be and 2O-mi Ti foils had equal transmittance of 75% for '3OO keV, 50 lcAJcm2, 100 ns e-beams, being lower than calculated one. In contrast to Ti foil, which surface was strongly etched by fluorine, no surface modification and no fatal damages were observed for Al-Be foils after lOOO laser shots and protracted fluorine exposure. It was shown that applied magnetic field of '-4kGs significantly reduced electron scattering both across and along laser cell at typical pumping conditions with 1 .5-atm pressure working gas. The energy fluence of scattered electrons fell down from '-lOO mJ/cm2 to -4 mJ/cm2 per pulse at 8.5-cm distance from the boundary of injected e-beams. Without magnetic field the scattered electrons were spread up to 20 cm, thus strongly irradiating optical windows and being a cause of additional induced absorption oflaser radiation.

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Section: Distribution Of Scattered Electrons In Laser Chambermentioning

confidence: 86%

Section: Laser Facilities and Experimental Proceduresmentioning

confidence: 99%

<title>Electron beam transport and foil stability in high-energy e-beam-pumped KrF lasers</title>

et al. 2001

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“…Specific pumping power in the gain region of GARPUN amplifier was determined earlier from the total e-beam energy deposition measured by means of a magnetically-inductive pressure gauge and from pumping distribution monitored by ArO fluorescence (Arlantsev et al, 1994). Gain measurements were done for typical gas mixtures F 2 /Kr/Ar ¼ 0.2/6/93.8% at total pressures p ¼ 1.25 2 1.75 atm.…”

Section: Gain and Absorption Measurements In Garpun Amplifiermentioning

confidence: 99%

GARPUN-MTW: A hybrid Ti:Sapphire/KrF laser facility for simultaneous amplification of subpicosecond/nanosecond pulses relevant to fast-ignition ICF concept

Зворыкин

Didenko²,

Ионин

et al. 2007

Laser Part. Beams

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The first stage of the petawatt excimer laser project started at the P.N. Lebedev Physical Institute, implements a development of multiterawatt hybrid GARPUN-MTW laser facility for generation of ultra-high intensity subpicosecond ultraviolet (UV) laser pulses. Under this project, a multi-stage e-beam-pumped 100-J, 100-ns GARPUN KrF laser was upgraded with a femtosecond Ti:Sapphire front-end, to produce combined subpicosecond/nanosecond laser pulses with variable time delay. Attractive possibility to amplify simultaneously short and long pulses in the same large-scale KrF amplifiers is analyzed with regard to the fast-ignition, inertial confinement fusion problem. Detailed description of hybrid laser system is presented with synchronized KrF and Ti:Sapphire master oscillators. Based on gain and absorption measurements at GARPUN amplifier and numerical simulations with a quasi-stationary code, we are predicting that 1.6 J can be obtained in a short pulse at hybrid GARPUN-MTW Ti:Sapphire/KrF laser facility, combined with several tens of joules in nanosecond pulse. Amplified spontaneous emission, which is responsible for the pre-pulse formation on a target, was also investigated: its acceptable level can be provided by properly choosing staged gain or loading the amplifiers by quasi-steady laser radiation. Fluorescence and transient absorption spectra of Ar/Kr/F 2 mixtures conventionally used in KrF amplifiers were recorded to find out the possibility for femtosecond pulse amplification at the broadband Kr 2 F (4 2 G ! 1,2 2 G) transition, which benefits in 100 times higher saturation energy density than for KrF (B ! X) transition.

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Self-focusing of UV radiation in 1 mm scale plasma in a deep ablative crater produced by 100 ns, 1 GW KrF laser pulse in the context of ICF

Зворыкин

Lebo

Ustinovskii

et al. 2020

Matter and Radiation at Extremes

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Experiments at the GARPUN KrF laser facility and 2D simulations using the NUTCY code were performed to study the irradiation of metal and polymethyl methacrylate (PMMA) targets by 100 ns UV pulses at intensities up to 5 × 1012 W cm−2. In both targets, a deep crater of length 1 mm was produced owing to the 2D geometry of the supersonic propagation of the ablation front in condensed matter that was pushed sideways by a conical shock wave. Small-scale filamentation of the laser beam caused by thermal self-focusing of radiation in the crater-confined plasma was evidenced by the presence of a microcrater relief on the bottom of the main crater. In translucent PMMA, with a penetration depth for UV light of several hundred micrometers, a long narrow channel of length 1 mm and diameter 30 μm was observed emerging from the crater vertex. Similar channels with a length-to-diameter aspect ratio of ∼1000 were produced by a repeated-pulse KrF laser in PMMA and fused silica glass at an intensity of ∼109 W cm−2. This channel formation is attributed to the effects of radiation self-focusing in the plasma and Kerr self-focusing in a partially transparent target material after shallow-angle reflection by the crater wall. Experimental modeling of the initial stage of inertial confinement fusion-scale direct-drive KrF laser interaction with subcritical coronal plasmas from spherical and cone-type targets using crater-confined plasmas seems to be feasible with increased laser intensity above 1014 W cm−2.

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Pumping of the GARPUN wide-aperture excimer laser by counterpropagating electron beams

Cited by 5 publications

References 2 publications

<title>Electron beam transport and foil stability in high-energy e-beam-pumped KrF lasers</title>

<title>Electron beam transport and foil stability in high-energy e-beam-pumped KrF lasers</title>

GARPUN-MTW: A hybrid Ti:Sapphire/KrF laser facility for simultaneous amplification of subpicosecond/nanosecond pulses relevant to fast-ignition ICF concept

Self-focusing of UV radiation in 1 mm scale plasma in a deep ablative crater produced by 100 ns, 1 GW KrF laser pulse in the context of ICF

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