A vacuum tube insert assembly includes a flared insert piece having an annular flange and a stem each constructed of glass. The stem extends axially from the flange. The flange surrounds a perimeter edge of a plug concavity defined by the stem. Feed-through pins pass axially through the stem and are sealed thereto. The pins terminate inside of the concavity to form a plug. A socket connects to the plug within the concavity and includes receptacles that removably couple to the pins, with an engagement feature preventing erroneous plug and socket connections. A method includes axially inserting the pins through the stem at a fixed relative position such that the pins are arranged within the plug concavity, sealing the stem such that the stem is vacuum-sealed to the pins, thereby forming the plug, and removably coupling mating receptacles of the socket to the pins.

An emitter, a field emission assembly, and an electromagnetic wave generator are provided, and the emitter is an emitter for emitting electrons in an electromagnetic wave generator and is in the form of a sheet in which a plurality of yarns including carbon nanotube (CNT) fibers are weaved.

Embodiments include an apparatus, comprising: a conductive base; an insulating substrate; an electron emitter disposed on the insulating substrate; a grid disposed adjacent to the electron emitter, the grid including a first conductive side and a second conductive side separate from the first conductive side; a plurality of posts; wherein: the first conductive side is attached to the insulating substrate through a first group of the posts; the second conductive side is attached to the insulating substrate through a second group of the posts; and the conductive base is attached to the insulating substrate through a third group of the posts.

A filament assembly 10 for an x-ray tube 20 can include a planar filament 11 electrically-coupled between and substantially-encircled by a pair of collector plates C1 and C2. The pair of collector plates C1 and C2 can support the planar filament 11 so that it does not twist or warp and align the filament assembly 10 within a cathode cup 33. The pair of collector plates C1 and C2 can block electrons emitted from a back side of the filament. Without the collector plates C1 and C2, back side electrons can change direction by about 180, hit the target, and distort a target electron spot. Each collector plate C1 or C2 can include holes H1 and H2. These holes H1 and H2 can aid in alignment of the collector plates C1 and C2 with electrodes 31 and electrode 32, can allow welding at a lower temperature, and can facilitate weld inspection.