X-ray spectra from high-intensity subpicosecond laser produced plasmas

Teubner, U.; Wülker, C.; Theobald, W.; Förster, E.

doi:10.1063/1.871481

Cited by 45 publications

(29 citation statements)

References 48 publications

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“…Thus various efforts have been made to improve the laser pulse absorption which plays a key role in laser target interaction in general and also the coupling efficiency, related to the emission. Among those efforts, there are examples of the strong increase of XR emission by the application of double pulses [1][2][3], changes of the contrast ratio (main laser pulse to background or uncontrolled prepulses from the amplifier system) [4][5][6], the optimization of the angle of incidence [7], the target thickness [8] and the target material [9,10], all those performed in the intensity range of I 0 ≈10 15 to 10 18 W/cm 2 , where I 0 is the laser intensity in the peak of the pulse. In a similar way the yield of HEP emission has also been improved in the same or higherintensity range [11].…”

Section: Introductionmentioning

confidence: 99%

Towards optimization of femtosecond laser pulse nanostructuring of targets for high-intensity laser experiments in vacuum

et al. 2021

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The interaction of intense femtosecond laser pulses with solid targets is a topic that has attracted a large amount of interest in science and applications. For many of the related experiments a large energy deposition or absorption as well as an efficient coupling to extreme ultraviolet (XUV), X-ray photon generation, and/or high energy particles is important. Here, much progress has been made in laser development and in experimental schemes, etc. However, regarding the improvement of the target itself, namely its geometry and surface, only limited improvements have been reported. The present paper investigates the formation of laser-induced periodic surface structures (LIPSS or ripples) on polished thick copper targets by femtosecond Ti:sapphire laser pulses. In particular, the dependence of the ripple period and ripple height has been investigated for different fluences and as a function of the number of laser shots on the same surface position. The experimental results and the formation of ripple mechanisms on metal surfaces in vacuum by femtosecond laser pulses have been analysed and the parameters of the experimentally observed “gratings” interpreted on base of theoretical models. The results have been specifically related to improve high-intensity femtosecond-laser matter interaction experiments with the goal of an enhanced particle emission (photons and high energy electrons and protons, respectively). In those experiments the presently investigated nanostructures could be generated easily in situ by multiple pre-pulses irradiated prior to a subsequent much more intense main laser pulse.

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Section: Introductionmentioning

confidence: 99%

Towards optimization of femtosecond laser pulse nanostructuring of targets for high-intensity laser experiments in vacuum

et al. 2021

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“…Since the last two decades, pressure in the range of multiple GBar became quite common [9]. Due to the short duration of the laser pulse, this pressure is produced rather fast [10]. One step further, if the laser intensity is big enough, the light pressure itself (ponderomotive pressure) may contribute to the shock onset along with the ion and electron pressure.…”

Section: Introductionmentioning

confidence: 99%

Laser-plasma induced shock waves in micro shock tubes

et al. 2017

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Shock wave generation with help of lasers or shock tubes, for example, is a common subject at macroscopic scale. On the other hand, the current tendency towards smaller scales becomes more and more important. In particular, shock waves in small channels or tubes with sub-mm or micron-sized diameter have attracted much interest within the last years. But downscaling of shock wave effects such as pressure decrease and Mach number attenuation during propagation, viscous and heat effects, laminar and turbulent flow is not necessarily straightforward from macro to micro or even nano range. Although several theoretical investigations are available in this new field, there is a strong demand on experiments, which are mostly missing due to the lack of suitable methods. The present work introduces a novel method for the generation of shock waves at microscale, namely laserinduced micro shock waves (LIMS). The LIMS method applies a femtosecond laser to induce an optical breakdown in a thin aluminum target located at the entrance of a micro tube. Subsequently, a shock wave is launched by the high pressure aluminum plasma and starts propagating into the tube. The topical work presents, for the first time, experimental investigations on direct micro shock wave generation and propagation at well-defined conditions in micron-sized tubes. They are performed for different conditions and tubes down to 50 μm diameter. Different from previous shock wave investigations in the mm-diameter range that involve pressure transducers, the present work applies non-contact measurements by optical methods. The experiments are supported by additional simulations. A one-dimensional numerical hydrocode is applied to simulate the shock wave generation process. Further propagation of the shock in a micro tube is analyzed by solving twodimensional Navier-Stokes equations. Both simulations agree well with the experimental results. Nomenclature L t laser pulse duration (fs-laser) E L laser pulse energy (fs-laser)

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“…The generation of x-ray fields whose frequencies are in the 'water window' [1,2] is currently a topic of great practical interest. The laser heating of plasmas is one of the processes which is very promising in attaining this goal.…”

Section: Introductionmentioning

confidence: 99%

Measurement of Anisotropic Soft X-Ray Emission during Radio-Frequency Current Drive in the JFT-2M Tokamak

Kawashima¹,

Hasegawa

Fuchs

et al. 1994

Jpn. J. Appl. Phys.

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We investigate electron-ion recombination in a powerful bichromatic laser field of frequencies ω L and 3ω L and consider the dependence of the recombination probabilities on the relative phase ϕ of the two field components. During this process a certain number of laser photons can be absorbed or emitted, yielding a spectrum of harmonics of the form ω X = E p + nω L + I io + U tot p , where E p is the initial electron energy, n the number of emitted or absorbed laser photons ω L , I io the ionization energy and U tot p the total ponderomotive energy of the bichromatic laser field. This process is of interest for the generation of highfrequency fields during the laser heating of plasmas. We shall evaluate the nonlinear recombination probabilities as a function of the relative phase ϕ of the two field components using the inverse form of the Keldysh-Faisal-Reiss model, also taking into account in an approximate way the Coulomb effects of the ion on the recombining electron. Moreover, we shall compare our quantum mechanical results with those obtained from a classical theory of recombination, developed recently, based on Bohr's correspondence principle.(Some figures in this article are in colour only in the electronic version; see www.iop.org)

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X-ray spectra from high-intensity subpicosecond laser produced plasmas

Cited by 45 publications

References 48 publications

Towards optimization of femtosecond laser pulse nanostructuring of targets for high-intensity laser experiments in vacuum

Towards optimization of femtosecond laser pulse nanostructuring of targets for high-intensity laser experiments in vacuum

Laser-plasma induced shock waves in micro shock tubes

Measurement of Anisotropic Soft X-Ray Emission during Radio-Frequency Current Drive in the JFT-2M Tokamak

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