Optical Diagnostics on ETA-II for X-Rays Spot Size

Gated and streak cameras have been used to look at a high current focused electron beam on a target, and the x-rays produced by that interaction. An optical camera images the optical transition radiation (OTR) from the beam hitting a carbon target to give focused beam profiles. Blackbody radiation from heavy metal targets is experimentally proven to be dominant. The roll bar technique is used as a thick knife edge to ‘image’ the x-ray spot produced by the beam-target interaction. The x-ray shadow is converted to visible photons using a scintillator and imaged using a gated optical camera. The scintillator thickness places a limit on the resolution of the diagnostic. A time dependent spot size can be constructed using multiple shots and assuming repeatability. Data will be presented from these techniques and compared to an x-ray pinhole camera.