Plasma cloud generation with intense electric fields inside a porous spherical cavity resonator excited by an external plane wave

Summary form only given. A porous spherical cavity resonator (PSCR) may be used to greatly increase the electric fields of a high power radio beam in order to produce isolated plasma clouds by neutral gas breakdown. The PSCR is a spherical polyhedron constructed from open surface polygons. The high-Q wave resonator can be excited at specific resonant frequencies by an external plane wave incident on the sphere. The resonant frequencies of the porous sphere are determined by the radius of the sphere and by the area of the openings in the surface of the sphere. The strength of the internal electric fields is influenced by the width of the conducting edges that comprise the polyhedron frame. The surface of the sphere contains polygons with dimensions much smaller than a wavelength. The transmission through the surface of the sphere decreases with the open area of the polygons. The optimum edge width is found where the external EM wave field excites the strongest internal field amplitudes by both letting the excitation field inside the sphere and keeping the internal fields contained. The WIPL-D EM simulation model is used to determine the optimum porous resonator for polyhedrons with 960 vertices (V960). All of the cavity modes for a solid spherical cavity resonator can be excited in the porous spherical cavity resonator (PSCR). With a high resonator Q, an EM plane-wave of 1 V/m can excite an internal electric field of over 1000 V/m. The spherical cavity modes are simulated to provide a variety of electric field distributions at the interior of the PSCR. The theory predicts that a wide variety of plasma clouds may be generated inside the sphere using selected resonant modes. This technique will be tested at NRL using a powerful (6 kW) plasma source operating at 2.54 GHz to illuminate a V960 ball fabricated out of stainless steel using stereo lithography processes.