Spectra and angular distributions of electrons emitted from laser-produced plasmas

Abstract

The spectra and angular distributions of high-energy electrons emitted from laser-produced plasmas have been measured. The plasmas were produced using short pulses from both CO2 and Nd : glass lasers to irradiate polyethylene slabs. For a CO2 laser intensity of approximately 3×1014 W/cm2 we find at least an order of magnitude greater energy conversion to high-energy electrons than with a Nd : glass laser intensity of approximately 5×1015 W/cm2. The angular distribution of electron emission is strongly peaked along the target normal (i.e., density gradient) and fine angular structure is observed.

High intensity femtosecond laser deposition of diamond-like carbon thin films

“…Suprathermal electrons have been previously observed in laser fusion studies, [12][13][14][15] where the laser intensities used are similar to those generated by the femtosecond pulses in our experiment. These suprathermal or sometimes termed ''fast electrons'' are characterized by a temperature that is on the order of 10-20 times higher than that of the background plasma temperature and scales as (I 2 ) a T b , where a and b generally have values between 0.25 and 0.50 and I is the laser intensity, is the laser wavelength, and T is the background plasma temperature.…”

Cut-off conditions and existence domains for large-amplitude ion-acoustic solitons and double layers in fluid plasmas

“…In this paper we describe an existence-parameter study of solitons and double layers (DLs) in plasmas composed of double Maxwell-Boltzmann electron species and two adiabatic fluid ion species where the ions are assumed to be singly charged. Such plasmas occur commonly in space (Temerin et al 1982;Mozer & Temerin 1983;Hudson et al 1983;Bostrom et al 1988) and many laboratory situations (Jones et al 1975;Nishida & Nagasawa 1986;Nakamura 1987), particularly in lasers (Giovanielli, Kephart & Williams 1976;Estabrook & Kruer 1978;Bezzerides, Forslund & Lindman 1978;Ludmirsky et al 1985), and have been the subject of several theoretical studies (Jones et, al. 1975;Buti 1980;Nishihara & Tajiri 1981;Raychaudhuri et al 1985;Erokhin & Tsybenko 1986;Bharuthram & Shukla 1986).…”

Imagerie médicale avec des sources X créées par laser

“…L'étude du rayonnement X dur obtenu lors d'une interaction laser-plasma a fait l'objet de nombreuses études dans plusieurs laboratoires. Les premières expériences ont été réalisées avec de très grosses installations laser de puissance délivrant des impulsions laser relativement longues (nanoseconde) dans le domaine de l'infra-rouge [2][3][4][5][6][7][8][9]. Le développement de ces sources X pour l'imagerie médicale a été proposé très tôt [10].…”