Magnetic deflection cathode ray tube system with electron gun having focus structure of a deposited resistive material

A high speed magnetic deflection cathode ray tube system having a selected magnetic deflection time constant comprising

• a glass envelope including a neck portion having first and second ends,
• a magnetic deflection yoke positioned at the second end of said neck portion and passing deflection flux through a predetermined portion of said neck portion, and
• an electron gun including a focus structure, means within said predetermined portion including at least a portion of said focus structure of said electron gun, said focus structure of said means within said predetermined portion including a tube of non-magnetic material having inner and outer surfaces and including a deposited film of a resistive material deposited on one or both of said surfaces, said resistive material being of a selected bulk resistivity .rho. and selected thickness t so said deposited film provides a selected time constant .tau. of said deposited film caused by the eddy currents induced therein by the deflection flux, in accordance with the relationship ##EQU2## where .mu. is the permeability of the resistive material, said means providing said time constant equal to or less than 100 nanoseconds.