How does a closed microfocus X-ray tube generate X-rays?

First, the microfocus X-ray tube of WELLMAN X-ray inspection equipment is closed. The microfocus X-ray tubes below 160KV are usually closed.

Accelerating the electrons and hitting a metal target is the easiest way to generate X-rays. After the electron hits the target, 99% of its lost kinetic energy is converted into thermal energy, which causes the target to generate heat; the remaining 1% of the kinetic energy emits photons, generates X-rays.

The closed microfocus X-ray tube also uses this method.

First of all, it is necessary to ensure that space, where the X-rays are generated is in a vacuum state, and the vacuum degree is not lower than 10-4 Pa, to avoid rapid oxidation and burnout of the filament that emits electrons.

The closed X-ray tube is vacuumized during production and then sealed, so that there is no need to vacuumize again, and it can be used after waiting for the low-voltage power supply to heat the filament.

                                                                                                   closed microfocus X-ray tube

As shown above, the high voltage generator applies a high voltage current to the tungsten wire of the cathode to generate an electron beam and provides sufficient voltage (ten to more than one hundred kilovolts) between the cathode and anode, so that the electron beam is in high energy and high-speed state.

After hitting the anode target (the material is also usually tungsten), it can reduce the area where the electron beam strikes after electrostatic focusing, that is, reduce the focus size. The 1% of the kinetic energy lost by the electron beam is converted into X-rays, which pass through the beryllium window and are emitted outward.

By adjusting the voltage and current of the X-ray tube, the penetrating power of X-rays and the number of electrons can be increased. You can click on previous articles to learn more.