A study of the secondary electrons yield produced by laser induced ions on Faraday cups as a function of beam angle

We analyze the dependence of the Secondary Electron Emission yield on the beam incidence angle (theta) in the case of Faraday cups used for diagnosis of laser-plasma. We show that this dependence follows a sec(alpha)(theta) law, consequently theta not equal 0 situations (i.e. non-normal incidence) should be treated with care to avoid wrong measurements.