Stabilizing effect of a magnetic field on a gas bubble produced at a microelectrode

The effect on the growth of a single hydrogen bubble of a magnetic field oriented normal to the surface of a microelectrode is investigated. Overpotential oscillations due to periodic growth and detachment of bubbles are correlated with high-speed camera images and particle tracking was used to follow the flow pattern. The bubbles on both horizontal and vertical microelectrodes grow bigger in the field, doubling in diameter before they break away in 5 Tesla. The effect is related to the influence of the magnetic field on the breakoff mechanism rather than to Ekman pumping driven by the Lorentz force.

► High-speed photography of growth of a single hydrogen bubble on a microelectrode.
► Bubbles grow twice the size in a magnetic field.
► Pumped Ekman flow driven by the Lorentz force, observed with tracer particles, is not responsible.
► Magnetic field controls the premature breakoff process, but it is not sure how.
► Bubbles that entirely cover the microelectrode fail to insulate it electrically.