Technique for measuring of LIA spot size on target by X-rays propagating in beam backward direction

Abstract

We are propose a technique for measuring of a focal spot size directly during the shot of a radiographic facility based on a linear induction accelerator. The key feature of the proposed method is the penumbral imaging in the direction backward to the electron beam propagation. Diagnostic has been installed in a backward hemisphere of the target chamber of a linear induction accelerator. It consists of two parallel edge-knife (roll-bars with 500 mm radius of curvature), a thin BGO scintillator, and a CCD camera with a 7 microseconds shutter. The performance and operability of the diagnostic was demonstrated on the linear induction accelerator with energy of electrons of 4 MeV. The first experimental results of the beam spot measurements are presented. A radiation transport modeling of the diagnostic scheme was performed using Monte-Carlo code PRIZMA. The effect of the scattered bremsstrahlung on the penumbral image in the backward direction was analyzed.

Soft X-ray radiography for measurements of a dense metal plasma created by intense relativistic electron beam on a tantalum target

“…The energy of electrons was 3.5 MeV, the beam current was 400 A and the pulse duration was 80 ns. The FWHM of the focal spot on the target measured using an X-ray pinhole camera [17] was 2 mm. A tantalum plate of 1 mm thick was used as the beam target.…”