KrF lasers for inertial fusion energy

Sethian, J. D.; Obenschain, S. P.; Lehmberg, R. H.; McGeoch, Malcolm W.

doi:10.1109/fusion.1997.687697

Cited by 6 publications

(5 citation statements)

References 16 publications

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“…Different angular distributions zla=Ø° (1) and zla=45° (2) of initial electron velocities in ebeam before the foil have been compared and demonstrated small influence on the transmittance. and input e-beam divergence 4a0 (1) or zlcet5° (2).…”

Section: E-beam Transport Through Al-be Foilmentioning

confidence: 99%

“…(2) Here, Q = No' is a product of the density of the scattering particles and the total collision cross section; E is a random number distributed uniformly in the interval (0, 1). For a homogeneous medium Q is a constant and Eqn.…”

Section: Monte Carlo Numerical Modellingmentioning

confidence: 99%

“…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). The foils (3) were supported by the hibachi structure (4) having the ribs of 2-mm width, 10-mmthickness and 8-mm inter-rib gaps.…”

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: E-beam Transport Through Al-be Foilmentioning

confidence: 99%

Section: Monte Carlo Numerical Modellingmentioning

confidence: 99%

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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“…laser-plasma interaction during the past two decades at 0.1-10.0 kJ-class single-shot KrF facilities AURORA (Los Alamos National Laboratory; LANL) (Rosocha et al, 1986(Rosocha et al, , 1987Harris et al, 1993), NIKE Naval Research Laboratory (NRL) (Obenschain et al, 1996;Pawley et al, 1997Pawley et al, , 1999Aglitskiy et al, 2002), SPRITE (RAL) National Institute of Advanced Industrial Science and Technology (Shaw et al, 1993(Shaw et al, , 1999Divall et al, 1996), ASHURA National Institute of Advanced Industrial Science and Technology (AIS & T) (Owadano et al, 1989(Owadano et al, , 1993(Owadano et al, , 1999(Owadano et al, , 2001 and GARPUN Lebedev Physical Institute (LPI) (Basov et al, 1993;Zvorykin & Lebo, 1999;Zvorykin et al, 2001Zvorykin et al, , 2004Zvorykin et al, , 2006aWang et al, 2002), and especially at rep-rate Electra laser (NRL) (Sethian et al, 1998Wolford et al, 2006) have proved that e-beam-pumped KrF laser might be the best challenge for direct-drive ICF power plant. To satisfy physical and economical requirements, they should be scaled to output energies of 30-60 kJ per one module, operating all together with the total laser energy of $2 MJ at rep-rate of 5 Hz and overall system efficiency of 7.5% (Svyatoslavsky et al, 1992;Von Rosenberg, 1992;McGeoch et al, 1997;Sethian et al, 2003).…”

Section: Krf Drivers In the Fast-ignition Icf Problemmentioning

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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“…Both are based on laser gated solid state switches. In this approach a small diode laser is used to flood the junction and Technologies that can meet the fusion requirements have been identified [5]. Electra will be built by integrating each component as it is developed to build a single facility.…”

Section: The Electra Laser Programmentioning

confidence: 99%

The Electra KrF laser program

Sethian

Hegeler

Myers

et al.

PPPS-2001 Pulsed Power Plasma Science 2001. 28th IEEE International Conference on Plasma Science and 13th IEEE International Pu

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Electra is a repetitively pulsed, electron-beam pumped, Krypton Fluoride (KrF) laser that will develop the technologies that can meet the Inertial Fusion Energy (IFE) requirements for durability, efficiency, and cost. Electra will have a 30 cm x 30 cm optical aperture, an output of 400-900 Joules, and run at 5 Hz. The main amplifier will be pumped with two 30 cm x 100 cm e-beams, each with V = 500 kV, I = 110 kA, and t = 100 nsec (flat top). The components that need to be developed are: a durable and efficient pulsed power system; a durable electron beam emitter; a long life, transparent pressure foil structure (hibachi); a laser gas recirculator; and long life optical windows. The technologies developed on Electra will be directly scalable to a full size fusion power plant beam line. We have built a first generation pulsed power system that can produce the necessary pulsed power parameters and repetition rate. This system has operated at 5 Hz for 90,000 shots (e.g. five hours), which is more than ample to develop the laser components. This paper gives an overview of the Electra program, and then concentrate on the results of our research on electron beam generation, transport, and deposition. This includes evaluation of various cathode and hibachi structures, as well as KrF laser modeling.

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KrF lasers for inertial fusion energy

Cited by 6 publications

References 16 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

The Electra KrF laser program

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