MEASUREMENTS OF THE ELECTROHYDRODYNAMIC INSTABILITY IN PLANAR GEOMETRY USING GALLIUM

The electrohydrodynamic (EHD) instability in planar geometry was obser ved using gallium as the working fluid. Electric fields in the range o f 0.12-0.26 MV/cm were applied in pulse durations up to 14.4 ms. The i nstability of the gallium surface was observed using a box camera and pulsed backlighting. The measured wavelengths of the instability range d from 1.2 to 17.0 mm, consistent with theoretical predictions provide d a field enhancement factor of 1.5 is assumed on the meniscus of the gallium. A transverse magnetic field of about 0.6 T was found to compl etely dampen the instability along the magnetic field at an applied el ectric field of 0.2 MV/cm; the transverse direction was unaffected. Th is result puts limits on the usefulness of an EHD ion source in magnet ically insulated diodes for inertial confinement fusion studies. (C) 1 995 American Institute of Physics.