Longitudinal space-charge effects in a retarding field energy analyzer

Experimental and theoretical work has been carried out to study the longitudinal space-charge effects in a retarding field energy analyzer. A one-dimensional model for both a mono-energetic beam and a thermal beam has been developed for this purpose. The study shows that, if the current density inside the device were higher than a critical value, the longitudinal space-charge effects would distort the measured energy spectrum. The measured mean energy will be shifted toward the low-energy side and the resulting spectrum will have a tail at the high-energy side. The measured FWHM and rms energy spread may also be affected.