ASU compact x-ray light source (IMAGE)
Caption
To make the first X-rays, the CXLS instrument was powered up to deliver around 4 keV photon energy. The first step takes place in the photoinjector of the light source. There, UV laser pulses are applied to a copper surface – at a rate of 1,000 pulses per second – each releasing a bunch of electrons into vacuum which are then accelerated in a strong electrical field. Next, the electron bunches are driven by a linear accelerator to nearly the speed of light and travel through a series of magnets that guide and focus the beam into an interaction chamber. In the final step, an infrared laser is shot nearly head-on into the path of the oncoming electrons. This results in the emission of powerful x-rays, in a process known as inverse Compton scattering, where the laser is key to the compact facility size. Strong magnetic fields shepherd the electrons into a capture sink. The emitted x-rays are sent downstream to interact with the sample of interest, such as proteins or other molecules (for the first x-ray demonstration, this step was omitted).
Credit
Shireen Dooling, Biodesign Institute at Arizona State University
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