Electrostatic grid device to reduce electron space charge

A vacuum electronics device comprising:

• a cathode comprising an electron-emitting region;
• an anode;
• at least one focus grid disposed entirely between the cathode and the anode, the at least one focus grid being laterally spaced apart from the electron-emitting region;
• and
• at least one acceleration grid disposed entirely between the cathode and the anode, the at least one acceleration grid being laterally spaced apart from the electron-emitting region and laterally between the electron-emitting region and the at least one focus grid,
• wherein the at least one focus grid is configured to be negatively biased relative to the acceleration grid, and
• wherein the acceleration grid is configured to be positively biased relative to the focus grid.

A method of reducing electron space charge in a vacuum electronics device, the method comprising:

• disposing at least one acceleration grid between an anode and a cathode facing the anode, the at least one acceleration grid being laterally outward from an electron-emitting region of the cathode;
• disposing at least one focus grid between the anode and the cathode, the at least one focus grid being laterally outward from the at least one acceleration grid and the electron-emitting region;
• coupling the at least one focus grid to a first power supply configured to negatively bias the at least one focus grid relative to the at least one acceleration grid;
• and
• coupling the at least one acceleration grid to a second power supply configured to positively bias the at least one acceleration grid relative to the at least one focus grid.