Oxide cathode of large area for plasma investigation

Pressed oxide cathode with emission coating as a nickel sponge filled with earth metal carbonate with 10×10 cm
²
area is described. This cathode consists of four plate 5×5 cm
²
which are heated with four separate heaters, each plate and heater are fixed on thin rods to a common platform 10×10 cm
²
. The design allows to replace plates and increase the number of plates up to the total cathode area 20×20 cm
²
and higher.