List of Topics

SfC Home > Physics > Electromagnetic Waves >


X-ray Generation

by Ron Kurtus (revised 20 September 2013)

There are three major ways that x-rays are produced or generated. The most common is the Bremsstrahlung process, where a high speed electron traveling in a material is slowed or stopped by the forces of an atom it encounters, thus emitting an x-ray.

Another method is K-shell emission, where a high energy electron knocks an electron from an inner orbit in an atom, and an x-ray is emitted with the replacement of that electron. The third method occurs in a synchrotron, which is a subatomic particle accelerator that creates high intensity x-rays used for nuclear studies.

Questions you may have include:

This lesson will answer those questions. Useful tool: Units Conversion

Bremsstrahlung process

The most common method of creating or generating x-rays is by the Bremsstrahlung process, where high energy electrons collide with a metal target, usually made of an alloy of tungsten combined with rhenium or molybdenum. Bremsstrahlung is German for braking or decelerating radiation. The phenomenon was discovered by Nikola Tesla around 1890.

(See the Biography of Nikola Tesla for more information on him.)

The way the Bremsstrahlung process works is that when a high energy electron hits or passes near the nucleus of an atom such as tungsten, it makes a sudden deceleration and change in direction. This loss of kinetic energy is transferred into radiation energy in the form of x-rays.

Note the the dual nature of electromagnetic radiation states that an x-ray may also be a high energy photon. In other words, a burst of radiation can be considered equivalent to release of a photon.

K-shell emission

Another method to create x-rays is through K-shell emission. In the Bohr model of the atom, the K-shell is the first shell or innermost shell of the atom. It is at the lowest energy state among the atom's shells.

When a high energy electron is accelerated into a metal target, some electrons knock the K-shell electrons out of orbit. An electron from a higher energy orbit or shell will jump down to replace the lost electron. Since the K-shell requires a lower state of energy, radiation energy is given in the form of an x-ray photon.

The explanation for K-shell x-ray emission using the electron cloud model of the atom is similar, although not as straightforward.

Since electrons are so very small compared with the nucleus of a moderately heavy metal atom, the probability of collision of an incoming electron with a K-shell electron is very small. This process is extremely inefficient in to producing a reasonable amount of x-rays.

Synchrotron radiation

A synchrotron is a large device used to study the effects of accelerating subatomic particles through high-powered magnetic fields at speeds near the speed of light. When electrons spiral around a magnetic field at high velocities, they give off radiation depending on their velocity. At high enough velocities, the radiation is in the form of x-rays. This is called synchrotron radiation.

Synchrotron radiation and a more simple cyclotron radiation are used as sources of x-rays primarily for laboratory nuclear studies.

Caused by change in velocity

Since velocity is speed in a specific direction, circular motion represents at change in velocity or acceleration (deceleration). When a charged particle such as an electron decelerates, it gives off electromagnetic radiation equivalent to the loss in energy from the deceleration. Thus, x-rays can be generated.

X-rays from Sun use same method

Since the Sun has extremely high energy electrons, as well as strong magnetic fields, it is a source of natural x-rays by the same synchrotron effect. The energy of those x-rays is greatly diminished by the time they get to the Earth.


The three major method to generate x-rays are the Bremsstrahlung process, K-shell emission and synchrotron radiation. In Bremsstrahlung process, a high speed electron traveling in a material is slowed or stopped by a nucleus, thus emitting an x-ray. In K-shell emission, a high energy electron knocks an electron from an inner orbit in an atom, and an x-ray is emitted with the replacement of that electron. In synchrotron radiation, electrons emit x-rays while spinning in a magnetic field.

Be courageous in what you do

Resources and references

Ron Kurtus' Credentials


Physics Resources

Viewing the Periodic Table of the Elements with X-rays - College experiment using K-shell method


Top-rated books on X-Rays

Top-rated books on Electromagnetic Waves

Questions and comments

Do you have any questions, comments, or opinions on this subject? If so, send an email with your feedback. I will try to get back to you as soon as possible.

Share this page

Click on a button to bookmark or share this page through Twitter, Facebook, email, or other services:


Students and researchers

The Web address of this page is:

Please include it as a link on your website or as a reference in your report, document, or thesis.

Copyright © Restrictions

Where are you now?

School for Champions

Physics topics

X-ray Generation

Electromagnetic Wave topics

Long wavelengths

Visible frequencies

Short wavelengths

Also see

Let's make the world a better place

Be the best that you can be.

Use your knowledge and skills to help others succeed.

Don't be wasteful; protect our environment.

You CAN influence the world.

Live Your Life as a Champion:

Take care of your health

Seek knowledge and gain skills

Do excellent work

Be valuable to others

Have utmost character

Be a Champion!

The School for Champions helps you become the type of person who can be called a Champion.