Compact energy storage using a modified-spiral PFL

The pulse length available from a coaxial PFL (pulse-forming line) of given length and dielectric constant has been doubled using a modified spiral technique. The modified spiral consists of a cylinder formed from a large number of insulated cables which are first laid parallel to the PFL axis and then given a moderate twist. The PFL is essentially a helical delay line in a form which accomplishes substantial pulse stretching without introducing significant turn-to-turn voltage gradients or distortion of the pulse shape. The technique can be used to increase the energy stored per unit length for a PFL of fixed impedance and pulse duration