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X-ray Tube Working Principle and Its Construction

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Do you ever wonder how X-ray tubes are constructed or the principle behind their workings? 

It’s fascinating to think about how the parts of a vital inspection tool are constructed and forged to serve its optimal purpose and utilized for the best quality control measures it’s made to serve. It is important here to state that x-rays are imaging technologies that use radiation to generate images that help detect component defects and ensure the safety of equipment production.

However, most of this imaging process takes place in the x-ray tube, and hence why we need to know how the x-ray is created and what goes on in the x-ray tube during the imaging process.

If you are ready then, shall we begin?


I. How is an X-ray Tube Constructed?

While you might be fascinated with the benefits of X-ray tubes and X-ray machines for their material inspection abilities, one other thing you might also like to consider will be how X-ray tubes are constructed. 

The first production of x-rays was by Roentgen in 1895 after producing electromagnetic radiation via a device that speeds up electrons between an anode and a cathode. Nonetheless, the basic working principle of x-ray production remains the same in this age, although adjustments have been made to produce an industrial functional beam generator.

The filament, also known as the cathode and target, also known as an anode, is encapsulated in a vacuum-filled envelope, which provides support and electrical insulation. Furthermore, the envelope is most often made from glass, even though some tubes contain envelopes made from ceramic or even metal. 


How is an X-ray Tube Constructed


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II. How are X-rays Generated in X-ray Tubes?

Frankly, the intensity of the X-ray generated by an X-ray tube significantly affects the quality of the X-ray image and consequently the accuracy of your X-ray inspection result. But how are these X-rays generated? 

The major components of an X-ray tube consist of an evacuated envelope containing a cathode (filament), an anode (target), exit window, and a focusing cup or cylinder. 

But here is the thing. 

Electrons are discharged using thermal emission when an electric charge passes through the tungsten filament. Given the high voltage difference between the anode and the cathode, these electrons are then expedited towards the anode (Target). Additionally, the electrons then striking the anode cause the outflow of X-rays, and the X-rays exit the tube via the narrow beryllium window.

Since only about 1% of the applied energy is converted to X-rays, converting electrons into X-rays is deemed a very inefficient process. Notwithstanding, the remainder of the energy is transformed into heat within the anode, and due to that fact, the back of the anode is usually cooled.


III. What is the Working Principle of X-ray Tubes?

For starters, X-ray tubes require a great deal of precision in setting the working parameters. However, you need to understand its basic working principles to know the suitable parameter settings for different inspection scenarios. 

The X-ray tube operates by discharging electrons from a heated cathode directed toward a target or a rotating anode disc, and the point where the electrons strike the target is known as the focal spot. Consequently, X-ray photons and imaging are emitted in all directions at the focal spot. Nevertheless, the required X-ray radiations are channeled towards the anode and are fixated by a collimator. Also, a photomultiplier is often employed to view the image contrast. Images received are then viewed on a photographic plate or digitally on a screen, and the light and dark spots on the film characterize the high and low element penetration of the x-ray image.

X-ray machines function by applying controlled voltage and current to the X-ray tube. So, operators monitor the beam’s intensity of X-rays by regulating voltage or electric charge. 


IV. Advantages of X-rays in Industry

X-rays are very beneficial to many industries, especially for assessing the quality of materials and products. The thing is, there are numerous other advantages across various sectors that X-rays offer. 

For instance, high result accuracy over other methods like visual inspection is possible because, with the use of the beams penetrating the test material, the various defects that the naked eye can never notice are visible when observed from the images generated on the photographic plate.

Also, samples can be reused as X-rays are NDTs (Non-Destructive Testing). Non-Destructive Testing is a technique of finding defects on a test material without damaging the material. 

Finally, the speed of getting results is almost instantly because, with x-rays, the amount of time required to carry out an x-ray test is reasonably short.


Advantages of X-rays


V. Applications of X-rays in Industry

In general, X-rays are applied to identify defects in products and materials, especially in the manufacturing industry. Nonetheless, there are many other applications in various sectors beyond flaw detection. 

Take the automotive industry, for example. A visual inspection will only result in multiple errors with numerous parts connected in the assembly line. However, the x-ray inspection is a more effective, efficient, and time-saving mode of tracing any mistakes made in the production line.

Likewise, for Print Circuit Boards (PCBs), integrated circuits (ICs) are tiny and mostly very difficult to see in the electronic manufacturing industry. Inspecting flaws like weak soldering and missing components can be strenuous. Thankfully, the inspection of PCBs is easier, faster, and efficient using PCB x-ray machines.

X-rays are also used in battery inspection to identify possible production flaws.



In conclusion, the fabrication and functionality of the x-ray machine are quite fascinating especially considering how it started in 1895. However, it is satisfying to know that it is advantageous with fast and reliable test results, user-friendly and less cumbersome features of the x-ray equipment, to mention a few.

And finally, the use of x-ray inspection as a quality control and quality assessment tool intersects several major industries such as the manufacturing, electrical, and medical industries.

Now that you have this information, we hope you get to apply it in your next X-ray tube purchase. It’ll be worth it. 

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