This Working Group is aimed at pursuing the study, by theory and/or simulations, of particle and radiation beams at extreme phase space density.
Typical topics of interest are: generation and preservation of high beam brightness, coherent modulation of phase space density, ultra-short bunches, ultra focused beams, transport and emittance characterization of self-injected plasma beams, external injection into plasma waves, particle wakefield schemes at high transformer ratio, etc.
Main aims are: optimization of advanced radiation beam production, in several spectral ranges (THz, UV-FEL, X, gamma), creation of secondary beams with advanced characteristics (bunched/polarized positrons, bunched neutrons, etc.).