Effect of sputtering in vacuum and repetitive breakdowns on field emission characteristic

Oxygen-free copper electrodes stored in the atmosphere for long term were used as test samples. Changes of field emission characteristics with 500 repetitive breakdowns and He ion beam sputtering were investigated in conjunction with analyses of electrode surface conditions by X-ray Photoelectron Spectroscopy (XPS). Experiments revealed that field emission currents were detected from electrodes used as the anode after 500 breakdowns, while for electrodes that were nontreated and the cathode after 500 breakdowns field emission currents were not detected. Anode and cathode surfaces were cleaned up by 500 breakdowns. Cathode surfaces were much more cleaned up than anode surfaces after repetitive 500 breakdowns.