What type of units charge a capacitor to a desired kilovoltage before discharging?

The type of units that charge a capacitor to a desired kilovoltage before discharging are pulse X-ray tubes. These devices work by using a capacitor to store electrical energy, which is then rapidly discharged to generate X-rays. The mechanism behind this involves charging the capacitor to a high voltage level, typically measured in kilovolts, before discharging it quickly to produce a burst of X-ray radiation.

Pulse X-ray tubes are specifically designed for applications that require short, intense bursts of radiation. This capability is especially useful in industrial radiography, where high-quality images are needed for inspection purposes. The rapid discharge of the stored energy in the capacitor allows for the generation of high-intensity X-ray pulses, facilitating effective and efficient imaging.

Other units listed, such as betatrons and linear accelerators, use different principles to produce radiation. Betatrons accelerate electrons in a circular path and rely on magnetic fields, while linear accelerators use electromagnetic fields to accelerate charged particles along a straight path. Van de Graaff generators produce high voltages through the movement of charge but are not typically used for generating X-rays in the same manner as pulse X-ray tubes.