Particle Simulations of High-Intensity Laser Interaction with Cone Targets

Hollow cone-shaped overdense plasma targets were used to investigate the generation and transport of fast particles in a high-intensity laser-matter interaction. Using 2d PIC simulations we examine cone, cone-wire and cone with an open tip target designs. Localization of electron jets and an angular spread are found in all cases of the laser-cone interaction. However, in the cone-wire geometry, at later times, the charge separation and radial electric fields around the wire collimate electron streams with an electron hot spot at the front end of the wire. The main mechanism of the electron transport in the targets is the reflection of electrons from the potential walls of the cone surface, and no significant surface electron transport is observed. Furthermore, the presence of harmonics in the reflected light suggests that the field intensity in the cone can be enhanced not only by simple multiple reflection but also by the field modulation due to harmonics generation. Moreover, it is found that the laser interaction with the open-tip cone can efficiently generate trains of short ( LT lambda) attosecond electron sheets close to the laser axis.5th International Conference on Inertial Fusion Sciences and Applications(IFSA 2007), Sep 09-14, 2007, Kobe, Japa

Supplementary data for the article: Mrđan, G. S.; Vastag, G. G.; Škorić, D. Đ.; Radanović, M. M.; Verbić, T. Ž.; Milčić, M. K.; Stojiljković, I. N.; Marković, O. S.; Matijević, B. M. Synthesis, Physicochemical Characterization, and TD–DFT Calculations of Monothiocarbohydrazone Derivatives. Structural Chemistry 2021, 32 (3), 1231–1245. https://doi.org/10.1007/s11224-020-01700-y.

Supplementary material for: [https://doi.org/10.1007/s11224-020-01700-y]Related to published version: [https://cherry.chem.bg.ac.rs/handle/123456789/4453

Effect of wave damping on the nonlinear saturation of stimulated Raman scattering in a finite homogeneous plasma

A question of stationarity of a nonlinear saturated regime of stimulated Raman backscattering in a finite homogeneous plasma is considered. Slowly varying envelope equations with the damping and the nonlinear frequency shift terms included are treated numerically. It is demonstrated by a space-time simulation of these equations that the variation in the damping rate drives the system through various dynamical regimes (from steady-state to chaotic). A simplified, space-only approach, based on the use of a numerical shooting method was applied to calculate the critical damping values corresponding to transitions between stationary and nonstationary saturated regimes. The corresponding bifurcation diagrams that enable prediction of the type of asymptotic behaviour of Raman instability are obtained and discussed

Quantifying self-organization in fusion plasmas

A multifaceted framework for understanding self-organization in fusion plasma dynamics is presented which concurrently manages several important issues related to the nonlinear and multiscale phenomena involved, namely,(1) it chooses the optimal template wavelet for the analysis of temporal or spatio-temporal plasma dynamics, (2) it detects parameter values at which bifurcations occur, (3) it quantifies complexity and self-organization, (4) it enables short-term prediction of nonlinear dynamics, and (5) it extracts coherent structures in turbulence by separating them from the incoherent component. The first two aspects including the detection of changes in the dynamics of a nonlinear system are illustrated by analyzing Stimulated Raman Scattering in a bounded, weakly dissipative plasma. Self-organization in the fusion plasma is quantitatively analyzed based on the numerical simulations of the Gyrokinetic-Vlasov (GKV) model of plasma dynamics. The parameters for the standard and inward shifted magnetic configurations, relevant for the Large Helical Device, were used in order to quantitatively compare self-organization and complexity in the two configurations. Finally, self-organization is analyzed for three different confinement regimes of the MAST device. Published by AIP Publishing

Simulations of relativistic laser-plasma interactions

To investigate the growth of instabilities in an underdense plasma, a number of simulations was carried out using the one-dimensional electromagnetic (EM) relativistic particle-in-cell code. A new type of Raman-like scattering was identified in a subcritical regime, which is over-dense for standard SRS. This novel instability is a parametric decay of the relativistic EM wave into a scattered light and an electron-acoustic (omega LT omega(p)) electrostatic wave. In the linear stage, resonant matchings are well satisfied, while the scattered Stokes wave is always driven near critical. During nonlinear saturation, due to rapid growth and strong localization of the Stokes wave, narrow intense EM soliton-like structures with down-shifted laser light trapped inside are formed; eventually, to be irradiated through the plasma-vacuum interface in the form of intense low-frequency EM bursts. This behavior alters the distribution of laser energy between transmission, scattering losses and generation of energetic electrons.22nd Summer School and International Symposium on the Physics of Ionized Gases, Aug 23-27, 2004, Tara Natl Pk, Yugoslavi

Stability of one-dimensional array solitons

The array soliton stability in the discrete nonlinear Schrodinger equation with dispersion for periodic boundary conditions is studied. The linear growth rate dependence on the discrete wave number and soliton amplitude is calculated from the linearized eigenvalue problem using the variational method. In addition, the eigenvalue problem is solved numerically by shooting method and a good agreement with the analytical results is found. It is proved numerically that the results fur the instability threshold fur the circular array coincides with the quasicollapse threshold for the case of open arrays With initial pulses in a form of array solitons

Spatiotemporal intermittency and chaos in stimulated Raman backscattering

Spatiotemporal dynamics of stimulated Raman backscattering in a finite, weakly dissipative plasma, with non-linear phase detuning taken into account, is examined numerically. The non-linear model of a three-wave interaction, involving quadratic coupling of slowly varying complex amplitudes of the laser pump, the backscattering and the electron plasma waves, exhibits spatiotemporal intermittency and chaos following a quasi-periodic scenario. Qualitative analysis of spatiotemporal patterns reveals increasing complexity both for the backscattered and the electron plasma wave as the relative pump strength increases. The transition from spatiotemporal intermittency to chaos is identified using methods from the theory of critical phenomena

Transition to turbulence via spatiotemporal intermittency in stimulated Raman backscattering

The spatiotemporal evolution of stimulated Raman backscattering in a bounded, uniform, weakly dissipative plasma is studied. The nonlinear model of a three-wave interaction involves a quadratic coupling of slowly varying complex amplitudes of the laser pump, the backscattered and the electron plasma wave. The corresponding set of coupled partial differential equations with nonlinear phase detuning that is taken into account is solved numerically in space time with fixed nonzero source boundary conditions. The study of the above open, convective, weakly confined system reveals a quasiperiodic transition to spatiotemporal chaos via spatiotemporal intermittency. In the analysis of transitions a dual scheme borrowed from fields of nonlinear dynamics and statistical physics is applied. An introduction of a nonlinear three-wave interaction to a growing family of paradigmatic equations which exhibit a route to turbulence via spatiotemporal intermittency is outlined in this work