A system and method for characterizing and charging a sample. The system includes a vacuum chamber, a first apparatus in the vacuum chamber and configured to characterize a sample, and a second apparatus in the vacuum chamber and configured to charge the sample. The second apparatus includes an electron gun configured to provide an electron beam to the sample and including an emission cathode biased to a first voltage relative to a reference voltage, a sample holder configured to support the sample, and a mesh located between the electron gun and the sample holder. Additionally, the second apparatus includes a first voltage supply configured to bias the mesh to a second voltage relative to the sample holder, and a second voltage supply configured to bias the sample holder to a third voltage relative to the reference voltage.