Modeling of the expansion of ultra-short-pulse laser-produced plasmas in magnetic fields

The study of hot plasma expansion in a uniform magnetic field is of interes t for many astrophysical applications. In order to observe this process in laboratory, an experiment is proposed in which an ultrashort laser pulse pr oduces a high-temperature plasma by irradiation of a jet of atomic clusters . The very high laser light absorption exhibited in such a gas of clusters facilitates the creation of a hot (> 5 keV), dense (10(19)-10(20) cm(-3)) p lasma with a sharp boundary. The small scale of the plasma (< 100 mu m radi us) permits the use of a strong magnetic held (> 1T). Pump-probe techniques can then be used to diagnose the density and magnetic field with high spat ial and temporal resolution (< 50fs). In the present work the expansion rat e of the plasma and deceleration caused by the magnetic held are examined a nalytically. Electrodynamical aspects related to the radiation and transfor mation of energy are considered as well. The results obtained can be used i n treating experimental data, studying magnetic R-T instabilities and other phenomena of astrophysical significance.