Abstract: A heater is built in an inner sleeve of an electron gun, and an impregnated type cathode is fixed at an end portion, on the grid electrodes side, of the inner sleeve. The inner sleeve, having an outside diameter ranging from about 1.0 mm to 1.4 mm and a length substantially equal to a primary spiral length of the heater is inserted in an outer sleeve. The outer sleeve has on the grid electrodes side a small-diameter portion having an outside diameter ranging from about 2.2 mm to about 2.6 mm and on the base end side a large-diameter portion having an outside diameter ranging from about 2.6 mm to 3.0 mm. The inner sleeve is inserted in the small-diameter portion and is fixed thereto by means of strap-like tabs. A holder is fixed around the outer peripheral portion of the large-diameter portion, and is assembled in a ceramic disk via the holder.

Abstract: Nonaqueous suspension for electrophoretic deposition of powders is disclosed which includes suspension consisting of ketonic solvent, nitrocellulose dissolved therein and powders suspended therein, strong acid, and strong base. In this case, the strong acid and the strong base both are added to the suspension such that conductivity of the suspension becomes 1 to 30 .mu. /cm.

Abstract: A flat thermionic cathode is provided with a substrate having at least one main heating element thereon to produce at least one substantially localized area of heat and a sub-heating element to substantially define a heating area, the localized area being produced within the heating area. A cathode element including electron emissive material is disposed at the localized area. While the localized area tends to produce a temperature gradient directed from the localized area toward the perimeter of the substrate so as to create thermal stress in the substrate along the perimeter thereof, the sub-heating element reduces this temperature gradient and, consequently, the thermal stress.

Abstract: A thermionic cathode structure includes a ceramic base plate, a heater layer of tungsten coated on the ceramic base plate, a cathode lead layer of tungsten formed on a ceramic insulating layer covering the heater layer, a base metal layer coated on the cathode lead layer, and a cathode material coated on the base metal layer.