Operation of ferroelectric plasma cathodes in magnetic field

During last decade the phenomenon of strong ferroelectric emission was studied widely in many laboratories all around the world. It was shown that the application of a driving pulse of ∼ 1 kV between solid rear and patterned from electrodes which cover a sample of a ferroelectric ceramics results in electron emission from the side of the front electrode. The current density of this electron emission varies from tens to hundreds A/cm². Ferroelectric cathodes can operate with a repetition rate up to several MHz without significant vacuum deterioration. Resent investigations showed that in plasma mode the strong electron emission occurs from surface discharge plasma formed on the ceramic surface near the edges of the front electrode pattern. This plasma has a density of ∼ 10¹² cm^-3, an electron temperature of 2-3 eV, and consists mostly from the material of the ferroelectric ceramics and the front electrode. Although ferroelectric plasma cathodes were used successfully in several experimental setups with applied magnetic field, particularly in relativistic magnetrons, the behavior of the ferroelectric plasma cathodes in the magnetic field and the dependence of the plasma parameters on the magnetic field strength were not studied yet. In the present work the results of experimental investigations of the operation of planar ferroelectric plasma cathodes in the uniform magnetic field are presented. It is shown the ferroelectric plasma cathodes can be successfully used in the magnetic field up to several kGs without substantial deterioration of the emissive properties. The dependence of plasma parameters on the applied magnetic field is reported.