Shielded, high-voltage probes

A series of high-voltage probes (≃300 kV) with a high input impedance (≳ 10 kΩ) and good frequency response (≲ 100 MHz) have been built. These probes use two concentric cylinders of resistive material; the inner cylinder is the larger resistor of a voltage divider and the outer cylinder shields the inner one from the stray capacitance which would normally degrade the response. These cylinders can be made of almost any resistive material provided that certain theoretical considerations based on nonuniform field penetration and probe impedances are taken into account. The theories discussed are compared to the experimental results of several probes with different resistive materials and relative dimensions. Of primary interest are the probe´s response, cost, weight, construction time, energy absorption, and system compatability (loading and shielding).