Ion beam generating mechanism in dense plasma focus

Abstract

Summary form only given. A model for generating high electric fields for charged particle acceleration in dense plasma focus (DPF) devices has been developed. The mechanism found to be responsible for the generation of high electric fields is a magnetic Rayleigh-Taylor instability seeded by major features in the electrode geometry of DPF devices. The model extends to DPF devices incorporating hollow as well as solid anodes. The magnetic Rayleigh-Taylor instability is responsible for the formation of a trapped magnetic flux cavity in the plasma sheath as it converges on axis. The cavity is formed in a roughly toroidal geometry with the major axis corresponding to the centerline of the DPF device. The cavity of trapped flux then undergoes a fast compression at the sheath implosion velocity. Rapid compression of magnetic field in this geometry sets up a strong transient electric field suitable for charged particle acceleration. The development of the magnetic cavity was calculated using a two-dimensional, resistive magnetohydrodynamic code. The transient electric field was calculated using a set of one-dimensional electromagnetic codes. Preliminary results produced electric fields of 0.2 MV/cm over accelerating lengths of 0.5 cm with a duration of a few nanoseconds. Results of charged particle acceleration in the unique electromagnetic field geometry are also discussed.