Detailed investigation of the DLC films in the transmissive photocathode DC gun application

摘要

Photocathode electron guns are key devices for high quality electron bunches generation. Development of the original photocathode conception — backside illuminated transmissive (for laser beam) photocathode — is going on at the Photo-gun test bench of the Joint Institute for Nuclear Research (JINR). Such cathode has an improved (in comparison with “classic” photocathode) quantum efficiency due to vectorial photoelectric effect. The influence of the diamond-like carbon (DLC) films production technology on quantum efficiency of prepared photocathode has been investigated. DLC films were deposited on silicon substrate and stainless steel mesh by plasma enhanced chemical vapor deposition from gas mixture CH4+Dz(Hz)+Ar and reactive magnetron sputtering using carbon target and gas mixture Ar and Dz(Hz). The concentration of elements in films was determined by Rutherford backscattering spectrometry and Elastic recoil detection analytical methods simultaneously. Raman spectroscopy at visible excitation wavelength was used for I(D)/I(G) ratio determination. Emission properties of the films were investigated, new results concerning extracted charge and quantum efficiency are presented.