Magnetic field effect on the induction of an electric microfield in potassium vapor partially ionized by a laser pulse

A laser-induced electric microfield in potassium vapor partially ionized by laser radiation and placed in an external magnetic field has been studied experimentally. It was found that the dependence of the electric field rise time on the magnetic field strength had a peak value when the plasma frequency is equal to the Larmor frequency. This finding allows us to measure the photoelectron density in weakly ionized potassium vapor. The results are explained in terms of a simple model that shows how the length of the photoelectron trajectory changes with the magnetic field. Received: 4 February 2002 / Revised version: 20 June 2002 / Published online: 25 September 2002 RID="*" ID="*"Corresponding author. Fax: +374-32/31172, E-mail: rdramp@ipr.sci.am