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| 1 | Studies of laser-plasma interaction physics with low-density targets for direct-drive inertial confinement schemes显示文摘Comprehensive understanding and possible control of parametric instabilities in the context of inertial confinement fusion (ICF) remains achallenging task. The details of the absorption processes and the detrimental effects of hot electrons on the implosion process require as mucheffort on the experimental side as on the theoretical and simulation side. This paper describes a proposal for experimental studies on nonlinearinteraction of intense laser pulses with a high-temperature plasma under conditions corresponding to direct-drive ICF schemes. We propose todevelop a platform for laser-plasma interaction studies based on foam targets. Parametric instabilities are sensitive to the bulk plasma temperatureand the density scale length. Foam targets are sufficiently flexible to allow control of these parameters. However, investigationsconducted on small laser facilities cannot be extrapolated in a reliable way to real fusion conditions. It is therefore necessary to performexperiments at a multi-kilojoule energy level on medium-scale facilities such asOMEGAor SG-III. An example of two-plasmon decay instabilityexcited in the interaction of two laser beams is considered. | V.Tikhonchuk Y.J.Gu O.Klimo J.Limpouch S.Weber | 2019 | Matter and Radiation at Extremes2019，4，4： | 3 |
| 2 | Fast magnetic energy dissipation in relativistic plasma induced by high order laser modes显示文摘Fast magnetic field annihilation in a collisionless plasma is induced by using TEM(1,0) laser pulse. The magnetic quadrupole structure formation, expansion and annihilation stages are demonstrated with 2.5-dimensional particle-in-cell simulations. The magnetic field energy is converted to the electric field and accelerate the particles inside the annihilation plane. A bunch of high energy electrons moving backwards is detected in the current sheet. The strong displacement current is the dominant contribution which induces the longitudinal inductive electric field. | Y.J.Gu Q.Yu O.Klimo T.Zh.Esirkepov S.V.Bulanov S.Weber G.Korn | 2016 | High Power Laser Science and Engineering2016，4，2： | 0 |
| 3 | Collective absorption of laser radiation in plasma at sub-relativistic intensities显示文摘Processes of laser energy absorption and electron heating in an expanding plasma in the range of irradiances Iλ^2=1015–1016 W·μm^2/cm^2 are studied with the aid of kinetic simulations.The results show a strong reflection due to stimulated Brillouin scattering and a significant collisionless absorption related to stimulated Raman scattering near and below the quarter critical density.Also presented are parametric decay instability and resonant excitation of plasma waves near the critical density.All these processes result in the excitation of high-amplitude electron plasma waves and electron acceleration.The spectrum of scattered radiation is significantly modified by secondary parametric processes,which provide information on the spatial localization of nonlinear absorption and hot electron characteristics.The considered domain of laser and plasma parameters is relevant for the shock ignition scheme of inertial confinement fusion. | Y.J.Gu O.Klimo Ph.Nicolai S.Shekhanov S.Weber V.T.Tikhonchuk | 2019 | High Power Laser Science and Engineering2019，7，3： | 0 |
| 4 | Time evolution of stimulated Raman scattering and two-plasmon decay at laser intensities relevant for shock ignition in a hot plasma显示文摘Laser–plasma interaction(LPI)at intensities 1015–1016 W·cm^-2 is dominated by parametric instabilities which can be responsible for a significant amount of non-collisional absorption and generate large fluxes of high-energy nonthermal electrons.Such a regime is of paramount importance for inertial confinement fusion(ICF)and in particular for the shock ignition scheme.In this paper we report on an experiment carried out at the Prague Asterix Laser System(PALS)facility to investigate the extent and time history of stimulated Raman scattering(SRS)and two-plasmon decay(TPD)instabilities,driven by the interaction of an infrared laser pulse at an intensity^1.2×1016 W·cm^-2 with a^100μm scalelength plasma produced from irradiation of a flat plastic target.The laser pulse duration(300 ps)and the high value of plasma temperature(~4 ke V)expected from hydrodynamic simulations make these results interesting for a deeper understanding of LPI in shock ignition conditions.Experimental results show that absolute TPD/SRS,driven at a quarter of the critical density,and convective SRS,driven at lower plasma densities,are well separated in time,with absolute instabilities driven at early times of interaction and convective backward SRS emerging at the laser peak and persisting all over the tail of the pulse.Side-scattering SRS,driven at low plasma densities,is also clearly observed.Experimental results are compared to fully kinetic large-scale,two-dimensional simulations.Particle-in-cell results,beyond reproducing the framework delineated by the experimental measurements,reveal the importance of filamentation instability in ruling the onset of SRS and stimulated Brillouin scattering instabilities and confirm the crucial role of collisionless absorption in the LPI energy balance. | G.Cristoforetti L.Antonelli D.Mancelli S.Atzeni F.Baffigi F.Barbato D.Batani G.Boutoux F.D'Amato J.Dostal R.Dudzak E.Filippov Y.J.Gu L.Juha O.Klimo M.Krus S.Malko A.S.Martynenko Ph.Nicolai V.Ospina S.Pikuz O.Renner J.Santos V.T.Tikhonchuk J.Trela S.Viciani L.Volpe S.Weber L.A.Gizzi | 2019 | High Power Laser Science and Engineering2019，7，3： | 0 |
| 5 | Dynamic stabilization of plasma instability显示文摘The paper presents a review of dynamic stabilization mechanisms for plasma instabilities. One of the dynamic stabilization mechanisms for plasma instability was proposed in the paper [Kawata, Phys. Plasmas 19, 024503(2012)],based on a perturbation phase control. In general, instabilities emerge from the perturbations. Normally the perturbation phase is unknown, and so the instability growth rate is discussed. However, if the perturbation phase is known, the instability growth can be controlled by a superimposition of perturbations imposed actively. Based on this mechanism we present the application results of the dynamic stabilization mechanism to the Rayleigh–Taylor instability(RTI) and to the filamentation instability as typical examples in this paper. On the other hand, in the paper [Boris, Comments Plasma Phys. Control. Fusion 3, 1(1977)] another mechanism was proposed to stabilize RTI, and was realized by the pulse train or the laser intensity modulation in laser inertial fusion [Betti et al., Phys. Rev. Lett. 71, 3131(1993)]. In this latter mechanism, an oscillating strong force is applied to modify the basic equation, and consequently the new stabilization window is created. Originally the latter was proposed by Kapitza. We review the two stabilization mechanisms, and present the application results of the former dynamic stabilization mechanism. | S.Kawata T.Karino Y.J.Gu | 2019 | High Power Laser Science and Engineering2019，7，1： | 0 |
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