Energy spectra of tailored particle beams from trapped single-component plasmas

A nondestructive technique was developed recently to create beams of electrons (or positrons) with small transverse spatial extent and high brightness from single-component plasmas confined in a Penning-Malmberg trap [T. R. Weber , Phys. Plasmas 90, 123502 (2008)]. A model for beam extraction was developed that successfully predicts the resulting beam profiles. This model is used here to predict the beam amplitudes and the energy distribution of the beams as a function of the exit-gate voltage. The resulting expressions, suitably scaled by the plasma parameters, depend only on the exit-gate voltage and the electrode radius. Predictions of the theory are confirmed using electron plasmas. This technique permits the formation of beams with both small transverse spatial extent and small energy spread. Applications involving antimatter beams (e.g., positrons) are discussed, including bright beams for improved spatial resolution, short pulses for time-resolved studies, and cold beams for improved energy resolution.