Quasistatic magnetic fields generated by nonrelativistic intense linearly polarized (LP) and circularly polarized (CP) laser pulses in an initially uniform underdense plasma in the collision-dominated limit are investigated analytically.Using a selfconsistent analytical model,we perform a detailed derivation of quasistatic magnetic fields in the laser pulse envelope in the collision-dominated limit to obtain exact analytical expressions for magnetic fields and discuss the dependence of magnetic fields on laser and plasma parameters.Equations for quasistatic magnetic fields including both axial componentB z and the azimuthal one B θ are derived simultaneously from such a selfconsistent model.The dependence of quasistatic magnetic field on incident laser intensity,transverse focused radius of laser pulse,electron density and electron temperature is discussed.
This paper analytically investigates the interaction of light filaments generated by a femtosecond laser beam in air. It obtains the Hamiltonian of a total laser field and interaction force between two filaments with different phase shifts and crossing angles. The property of the interaction force, which leads the attraction or repulsion of filaments, is basically dependent on the phase shift between filaments. The crossing angle between two filaments can only determine the magnitude of the interaction force, but does not change the property of the force.
A new laser propulsion scheme with a high specific impulse is proposed in this paper.An extremely thin polyimide film is used as the propellant to eliminate thermal diffusion and sputter from the target material.It is found that a high specific impulse of 1520 s can be achieved at 10 11-W/cm 2 laser intensity because of economic use of the propellant.The influences of the laser intensity and the ablation area on the specific impulse are also studied in the experiment.
The collisional current-filamentation instability (CFI) is studied for a nonrelativistic electron beam penetrating an infinite uniform plasma. It is analytically shown that the CFI is driven by the drift-anisotropy rather than the classical anisotropy of the beam and the background plasma. Therefore, collisional effects can either attenuate or enhance the CFI depending on the drift-anisotropy of the beam-plasma system. Numerical results are given for some typical parameters, which show that collisional effects cannot stabilize but enhance the CFI in a dense plasma. Thus, the CFI may play a dominant role in the fast electron transport and deposition relevant to the fast ignition scenario (FIS).
The driving mechanism of solar flares and coronal mass ejections is a topic of ongoing debate, apart from the consensus that magnetic reconnection plays a key role during the impulsive process. While present solar research mostly depends on observations and theoretical models, laboratory experiments based on high-energy density facilities provide the third method for quantitatively comparing astrophysical observations and models with data achieved in experimental settings.In this article, we show laboratory modeling of solar flares and coronal mass ejections by constructing the magnetic reconnection system with two mutually approaching laser-produced plasmas circumfused of self-generated megagauss magnetic fields. Due to the Euler similarity between the laboratory and solar plasma systems, the present experiments demonstrate the morphological reproduction of flares and coronal mass ejections in solar observations in a scaled sense,and confirm the theory and model predictions about the current-sheet-born anomalous plasmoid as the initial stage of coronal mass ejections, and the behavior of moving-away plasmoid stretching the primary reconnected field lines into a secondary current sheet conjoined with two bright ridges identified as solar flares.
