Electron acceleration in ionizable gas

In a gas-discharge device of the type having a generally planar cathode for emitting electrons and a generally planar anode for accelerating said electrons toward a luminescent target, said anode and said cathode being mutually parallel and the space between said cathode and said anode containing an ionizable gaseous atmosphere, the combination comprising

• a plurality of planar electron-transmissive accelerator electrodes mounted in spaced parallel relationship between said cathode and said anode,
• insulator means insulating said electrodes from one another and from said cathode and said anode, and permitting said electrons to pass as they travel from said cathode toward said target, and
• means connecting to said electrodes voltages which are respectively positive relative to the voltage level of said cathode, which voltages increase in value from the one of said electrodes which is closest to said target,
• the voltage difference between adjacent ones of said accelerator electrodes being less than the ionization voltage and the surface breakdown voltage therebetween,
• said electron-transmissive accelerator electrodes are respectively provided with a plurality of holes through which said electrons must pass as they travel from said cathode to said anode, and
• the minimum dimension of said holes being less than the Debye length of the gaseous atmosphere in which they are located.