Force on an Asymmetric Capacitor

TL;DR

This paper investigates the Biefeld-Brown effect in asymmetric capacitors, analyzing potential physical mechanisms and emphasizing the need for further experiments to understand the force's origin, with implications for propulsion technologies.

Contribution

The study provides a detailed analysis of possible mechanisms behind the Biefeld-Brown effect and highlights the necessity of new theoretical models and experiments for clarification.

Findings

Ionic wind is too small to explain the force.

Ionic drift could account for the force magnitude.

Further experiments are needed to understand the effect's nature.

Abstract

When a high voltage (~30 kV) is applied to a capacitor whose electrodes have different physical dimensions, the capacitor experiences a net force toward the smaller electrode (Biefeld-Brown effect). We have verified this effect by building four capacitors of different shapes. The effect may have applications to vehicle propulsion and dielectric pumps. We review the history of this effect briefly through the history of patents by Thomas Townsend Brown. At present, the physical basis for the Biefeld-Brown effect is not understood. The order of magnitude of the net force on the asymmetric capacitor is estimated assuming two different mechanisms of charge conduction between its electrodes: ballistic ionic wind and ionic drift. The calculations indicate that ionic wind is at least three orders of magnitude too small to explain the magnitude of the observed force on the capacitor. The ionic drift transport assumption leads to the correct order of magnitude for the force, however, it is difficult to see how ionic drift enters into the theory. Finally, we present a detailed thermodynamic treatment of the net force on an asymmetric capacitor. In the future, to understand this effect, a detailed theoretical model must be constructed that takes into account plasma effects: ionization of gas (or air) in the high electric field region, charge transport, and resulting dynamic forces on the electrodes. The next series of experiments should determine whether the effect occurs in vacuum, and a careful study should be carried out to determine the dependence of the observed force on gas pressure, gas species and applied voltage.