Measurements of electron-induced neutrons as a tool for determination of electron temperature of fast electrons in the task of optimization laser-produced plasma ions acceleration

High intensity laser-plasma interaction has attracted considerable interest for a number of years. The laser-plasma interaction is accompanied by generation of various charged particle beams, such as high-energy proton and ions with high charge to mass ratio (Q/M; same as multi-charged ions). Results of simultaneous novel measurements of electron-induced photonuclear neutrons (photoneutron), which are a diagnostic of the laser-plasma interaction, are proposed to use for optimization of the laser-plasma ion generation. The proposed method is demonstrated by the laser irradiation with the intensity of 1 × 10(21) W/cm(2) on the metal foil target. The photoneutrons are measured by using NE213 liquid scintillation detectors. Heavy-ion signal is registered with the CR-39 track detector simultaneously. The measured signals of the electron-induced photoneutrons are well reproduced by using the Particle and Heavy Ion Transport code System. The results obtained provide useful approach for analyzing the various laser based ion beams.

Macroscopic evidence of soliton formation in multiterawatt laser-plasma interaction

A novel physical phenomenon has been observed following the interaction of an intense (10(19) W/cm(2)) laser pulse with an underdense plasma. Long-lived, macroscopic bubblelike structures have been detected through the deflection that the associated electric charge separation causes in a proton probe beam. These structures are interpreted as the remnants of a cloud of relativistic solitons generated in the plasma by the ultraintense laser pulse. This interpretation is supported by an analytical study of the soliton cloud evolution, by particle-in-cell simulations, and by a reconstruction of the proton-beam deflection.

Magnetic field energy dissipation due to particle trapping in a force-free configuration of collisionless pair plasmas

It is shown by using a two-dimensional, fully relativistic, electromagnetic particle-in-cell simulation code that a force-free magnetic configuration in collisionless, electron-positron (pair) plasmas becomes unstable against current-driven Buneman instability and subsequently there occurs a strong magnetic field energy dissipation associated with collisionless magnetic reconnection, which can be driven by particle trapping due to two-dimensional electric potentials remaining in the nonlinear stage of the initial current-driven Buneman instability. About 43% of the initial magnetic field energy dissipates and is transformed to plasma heating as well as high-energy particle production. The energy spectrum in the high-energy region is given by an exponential type with two temperatures. We also show the simulation results for the electron-ion plasma to compare the effect of the mass ratio of the electron and proton.

Relativistic solitons in magnetized plasmas

The results of analytical and numerical investigations on the properties of one-dimensional (nondrifting) solitons of relativistic amplitude, in the presence of an externally imposed uniform magnetic field B0, are presented and compared with those of the unmagnetized plasma theory (Esirkepov et al., Pis'ma Zh. Eksp. Teor. Fiz. 68, 33 (1998) [JETP Lett. 68, 36 (1998)]). The presence of a uniform longitudinal magnetic field, the intensity of which corresponds to an electron cyclotron frequency Omega(e)=eB(0)/m(e)c that is a non-negligible fraction of the laser frequency omega(0), has important consequences on the properties of relativistically intense solitons. The region of the parameter space (omega(0),Omega(e)) where magnetized solitons exist is determined analytically, and new conditions of breaking due to the total density depletion are given. It is shown that stable high energy magnetized solitons can be produced.