Calculation and design of grids in Pierce guns

Codes and methods which have been used to design grids for Pierce guns are described. A novel, very simple grid concept is described. It provides about a 50% reduction in cutoff voltage over standard grids, for a given number of grid rings and outer vanes. Alternatively, the number of grid rings and vanes required to satisfy a given cutoff requirement can be reduced. This, in turn, leads to a reduction in cathode loading and lower tunnel emittance. It is shown that the codes TMLBMC and DEMEOS are in excellent agreement with experimental data and that they are useful in the design of these grids. So-called T-grids have led to better focusing and greatly improved tube performance.<>