Hybrid modeling of relativistic underdense plasma photocathode injectors

Xi, Y. and Hidding, B. and Bruhwiler, D. and Pretzler, G. and Rosenzweig, J. B. (2013) Hybrid modeling of relativistic underdense plasma photocathode injectors. Physical Review Special Topics: Accelerators and Beams, 16 (3). 031303. ISSN 1098-4402 (https://doi.org/10.1103/PhysRevSTAB.16.031303)

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Abstract

The dynamics of laser ionization-based electron injection in the recently introduced plasma photocathode concept is analyzed analytically and with particle-in-cell simulations. The influence of the initial few-cycle laser pulse that liberates electrons through background gas ionization in a plasma wakefield accelerator on the final electron phase space is described through the use of Ammosov-Deloine-Krainov theory as well as nonadiabatic Yudin-Ivanov (YI) ionization theory and subsequent downstream dynamics in the combined laser and plasma wave fields. The photoelectrons are tracked by solving their relativistic equations of motion. They experience the analytically described transient laser field and the simulation-derived plasma wakefields. It is shown that the minimum normalized emittance of fs-scale electron bunches released in mulit-GV/m-scale plasma wakefields is of the order of 10-2 mm mrad. Such unprecedented values, combined with the dramatically increased controllability of electron bunch production, pave the way for highly compact yet ultrahigh quality plasma-based electron accelerators and light source applications.