Performance of free electron lasers is highly dependent of the beam phase space distribution. Characterizing the full six-dimensional phase space distribution is time consuming and often requires specialized diagnostics elements. Generative phase space reconstruction (GPSR) has been shown to provide fast and detailed reconstructions of the beam structure in six-dimensions. Nevertheless, previous implementations of GPSR rely on a transverse deflecting cavity (TCAV), which is a specialized diagnostic element not available at every section of the beamline. This experiment at the Pohang Accelerator Laboratory X-ray Free Electron Laser introduces the first implementation of six-dimensional GPSR by only using standard beamline elements commonly available, such as an accelerating cavity and dipole magnets on a chicane. Furthermore, this work presents the first experimental validation of GPSR by propagating the reconstructed beam distribution and accurately reproducing independent phase space measurements downstream, revealing that the reconstructed phase space closely resembles the true physical distribution. These results further establish GPSR as a flexible method that can accommodate a wide range of accelerator facilities for fast and detailed phase space diagnostics.

This study was led by Pohang Accelerator Laboratory, and was done in collaboration with SLAC, UChicago and the Center for Bright Beams.

Reference: 

S. Kim, J. P. Gonzalez-Aguilera, R. Roussel, G. Kim, A. Edelen, M.-H. Cho, Y.-K. Kim, C. H. Shim, H. Heo, and H. Yang, “Deployment and validation of predictive 6-dimensional beam diagnostics through generative reconstruction with standard accelerator elements,” Sci Rep, vol. 15, no. 1, p. 43049, Dec. 2025, doi: 10.1038/s41598-025-26954-6.