American Society for Nondestructive Testing (ASNT) Radiographic Testing Practice Test

A betatron is primarily used to generate high-energy electrons, making this the correct choice. This device operates on the principle of acceleration, using alternating electric fields to accelerate electrons to relativistic speeds. When these high-energy electrons are directed towards a target, they can produce x-rays through the process of bremsstrahlung, which is the rapid deceleration of electrons when they come close to atomic nuclei.

This capability of the betatron to produce high-energy electrons is particularly valuable in various applications, such as radiation therapy and industrial radiography, where the energy of the x-rays needs to be sufficient to penetrate dense materials. The other options listed do not accurately capture the primary function of a betatron. Enhancing image clarity, controlling radiation levels, and focusing the x-ray beam are important aspects of x-ray technology, but they are not the main purpose of this specific tool.