Some mechanisms and time scales for emittance growth

Publisher Website
Google Scholar
Abstract
We discuss several processes which affect transverse rms emittance and analyze the growth rate for two of them: (1) a fast process by which electrostatic self‐field energy is converted into fluid motion, and (2) a slow process by which a nonlinear focusing force converts beam‐size mismatch energy into additional emittance growth. The analysis for these two cases is done by solving the particle equation of motion. For the latter case we find that the final emittance depends primarily on the beam‐size mismatch and that the time scale is inversely proportional to the nonlinearity parameter. We also discuss, in a more general way, another process by which wave‐breaking in phase space causes partial conversion of fluid motion to quasi‐thermal energy. In all cases, insight is gained by splitting the mean‐square emittance into fluid‐motion and quasi‐thermal parts. Among other benefits, this allows a clearer understanding of the wave‐breaking process.

This publication has 0 references indexed in Scilit: