Radiation-Induced Noise in UMPC-Type Current Probes: IEMP Response of the CurrentMeasurement System

摘要

The purpose of these tests was to determine the radiation-induced noise responseof the probes in fluences up to the maximum obtainable from our high-intensity flash x-ray (HIFX), somewhat above 2 x 10 to the 11th power rads(Si)/s. This noise level determines the signal-to-noise ratio that can be obtained in low level current measurements in the pulsed radiation environment, such as input photocurrents to silicon-on-sapphire devices. The UMPC probes themselves are a significant issue because they are at present the most satisfactory way of measuring currents in pulsed radiation; in spite of their limitations a better means is not available. Not only is the internal electromagnetic pulse (IEMP) response of the probe itself presented, but also that of unavoidably related structures is addressed, such as the circuit conductors connecting to the probes. It is found that these connections typically are the limiting factor in determining the measurement system noise level. The lowest noise level attained, about 2.5 mA at 3 x 10 to the 11th power, was with a two-core transformer. Current probe, IEMP, Radiation-induced noise.