What is the approximate voltage difference maintained between the photocathode and anode in an image intensifier?

In an image intensifier, the voltage difference maintained between the photocathode and the anode is crucial for its operation. The correct answer reflects the standard operating range needed to effectively accelerate the electrons emitted from the photocathode towards the anode.

The typical voltage range of 25,000 to 30,000 volts ensures that the electrons are not only adequately accelerated but also produce a sufficient amount of light in the output phosphor. This high voltage difference enhances the overall gain of the image intensifier, allowing it to amplify low-light signals significantly, which is essential for applications like night vision and fluoroscopy.

This voltage is necessary for effective electron flow and interaction without causing damage to the components. Lower voltages may not provide sufficient acceleration, resulting in weaker imaging, while excessively high voltages could lead to detrimental effects, including potential damage to the device due to excessive current or breakdown of the components. Thus, the choice of 25,000 to 30,000 volts aligns with optimal operational requirements for image intensifiers.