New Applications of Impedance Networks as Analog Computers for Electronic Space Charge and for Semiconductor Diffusion Problems

Starting from a general partial differential equation of the second order, which includes the equations of Laplace, of Poisson, and those of semiconductor diffusion problems, an equivalent equation with finite differences is discussed. This leads to resistance and to resistance-capacitance networks. Resistance chains are applied to high vacuum diodes of one-dimensional character (plane, circular, and spherical systems). Results are within about a per cent of the exact solutions. Resistance-capacitance chains and networks are applied to semiconductor diffusion problems with space and surface recombination, yielding known and new results pertaining to p-n diodes. A plane resistance network is applied to a triode with electronic space charge and yields the anode current vs grid voltage curve within a few per cents of the published value. These results may lead to considerable savings in the design of new tubes.