Optimum design of a conductor pattern for a high speed bubble drive circuit

This paper describes a design method for an optimum bubble drive circuit composed of two meandering conductor patterns. The distribution of an average vertical component of the magnetic field produced by the patterns is calculated. The distribution is decomposed into Fourier spectra, from which a distortion factor D is obtained. A factor F which indicates the degree of deformation of the progressive magnetic field is introduced. It is clarified that F has a minimum for any field distribution when the patterns are driven with cosine- and sine-wave currents and that F, which is a simple function of D in that case, has a minimum at (gap width)/(pattern width) = 1/2 for any spacer thickness.