FEL

FEL stands for Free Electron Laser, which is a advanced laser technology nowadays and has wide application fields. FEL emits a beam of electromagnetic radiation with a wavelength covering a wide range from the far infrared and near ultraviolet to the X-ray region. It is a very efficient and specific application field.

FEL is built based on the basic principles of particle accelerators and electromagnetic radiation. A traditional Free Electron Laser, which is the most commonly used type of FELs, is mainly composed of an electron gun, a drift tube, an undulator and a collecting mirror. Electron gun is an apparatus that emits electrons, while drift tubes is a kind of accelerator that accelerates the emission of electrons. In the undulator, it is a special kind of an electromagnet which enables electrons to oscillate at a certain frequency.

In addition, Free-Electron-Lasers need power supplies to drive the electron gun and undulator, which are the basic requirements to keep FEL working. The type of power supplier depends on the application type of FEL, it may be DC, pulsed or pulse modulated power supplies.

Once the electron beam is generated and accelerated, it is then deflected and travels through a series of straight and curved sections. The two ends of the curved sections are quasi-periodic and have opposite magnetic fields, allowing the electrons to oscillate. As the electrons travel through the undulator, an alternating electromagnetic field is formed, causing the electrons to “hop” along the undulator in a wave-like motion.

The radiation generated from the oscillating electron beam will pass through the collecting mirror before being collected and delivered as useful output. The collecting mirror not only collects the radiation emitted from the undulator, it also changes the focal length of the beam, resulting in the beam being focused more accurately. This process increases the degree of accuracy and directionality of the beam.

There are many application fields for FEL, these are mainly in areas such as accessing certain molecules and materials, biomedical applications, high resolution imaging, additive manufacturing, defense related applications, manufacturing of high performance optics, and material surface analysis.

In conclusion, FEL is an advanced laser technique which has wide application fields. It is mainly composed of an electron gun, a drift tube, an undulator and a collecting mirror. This technology has been widely used in a lot of areas such as accessing certain molecules and materials, biomedical applications, high resolution imaging, additive manufacturing, defense related applications, manufacturing of high performance optics, and material surface analysis.