Open AccessMeasurement of the horizontal beam emittance of undulator radiation by tandem‐double‐slit optical system
Author(s) -
Kagoshima Yasushi,
Akada Tatsuki,
Ikeda Takumi,
Kawashima Motoki,
Aoi Yuki,
Takayama Yuki
Publication year - 2020
Publication title -
journal of synchrotron radiation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.172
H-Index - 99
ISSN - 1600-5775
DOI - 10.1107/s1600577520004415
Subject(s) - undulator , optics , physics , thermal emittance , beam (structure) , tandem , ellipse , materials science , astronomy , composite material
A tandem‐double‐slit optical system was constructed to evaluate the practical beam emittance of undulator radiation. The optical system was a combination of an upstream slit (S 1 ) and downstream slit (S 2 ) aligned on the optical axis with an appropriate separation. The intensity distribution after the double slits, I ( x 1 , x 2 ), was measured by scanning S 1 and S 2 in the horizontal direction. Coordinates having intensity were extracted from I ( x 1 , x 2 ), whose contour provided the standard deviation ellipse in the x 1 – x 2 space. I ( x 1 , x 2 ) was converted to the corresponding distribution in the phase space, I ( x 1 , x 1 ′). The horizontal beam emittance was evaluated to be 3.1 nm rad, which was larger than the value of 2.4 nm rad estimated by using ray‐tracing. It was found that the increase was mainly due to an increase in beam divergence rather than size.