Optimization and performance of atmospheric Fused Hollow Cathodes

► Minimum separation of cathode walls for atmospheric plasma ignition depends on gas. ► Minimum separation of cathode walls to ignite plasma depends on type of generation. ► Minimum wall separation broader for molecular gases both for rf and pulsed dc powers. ► Minimum wall separation to ignite plasma smaller for pulsed dc than for rf power. ► Plasma reactor design and type of plasma generation affect plasma-chemical processes.