Pressure dependence of spontaneous magnetic fields in laser produced plasma

Abstract

Magnetic fields of strength up to hundreds of gauss nay appear spontaneously when a plasma is produced either by laser-induced breakdown of a gas [1] or by laser irradiation of a solid target [2]. In the latter case the magnetic fields exhibit a systematic dependence on the density or the ambient background gas into which the plasma streams [3]. We have investigated the space and time behavior of the fields produced by irradiation of an aluminum slab with 6 joule, 20 nanosecond (10¹⁰ : watt/ cm²) pulses of 1.06 micron radiation, in backgrounds of H^, UQ, H2< and Ar. An equation describing the time development of die magnetic field can be obtained from the electron equation of notion