Design principles for vector inversion generators

Vector Inversion Generators (VIG), were invented in the 60’s by Fitch and Howell (1). They consist of two parallel plate transmission lines, wound on a common mandrel and sharing a common conductor. VIG’s are a compact electrostatic energy storage device that can convert the stored energy into a traveling RF wave in one component-one step process. In that regard, they are unique. VIG’s have been periodically investigated for a number of applications, none of which led to wide spread applications. In recent years (2, 3), there have been a number of advances in materials technology and improvements in efficiency, life, and ease of manufacture. In our laboratory, we have constructed VIG’s that can function at voltages up to 1 MV with limited lifetime in a “coke can” size package. Similarly, we routinely operate VIG devices at high repetition rates for millions of charge discharge cycles. In the course of developing these devices, we have formulated a series of design equations and methodology that allow us to bound the parameter range that must be met for specific performance specifications, Usually, the actual performance of the devices constructed by this methodology, are within a few percent of theoretical predictions. In this paper, we will describe the basic equations that allow determination of the VIG erection time, amount of energy available at the output of the device and the restrictions on the value of the load impedance necessary for efficient energy transfer. We will describe a method for determining the maximum current, I, and dI/dt. Using our methodology, we will present data from several point designs that illustrate the utility of our methodology and comment on applications such as X-ray production, impulse generators, and as an RF source.