Filament assembly having reduced electron beam time constant

An x-ray tube, comprising:

• a vacuum enclosure;
• an anode positioned within the vacuum enclosure and including a target surface;
• and
• a cathode positioned with respect to the anode, the cathode including:
• a filament assembly, comprising:
• a heat sink;
• a plurality of filament segments configured for simultaneous emission of a beam of electrons for impingement on the target surface of the anode, the filament segments being electrically connected in series, wherein each filament segment includes:
• first and second end portions, the end portions being thermally connected to the heat sink;
• and
• a central portion interposed between the first and second end portions, the central portion having a modified work function for preferentially emitting electrons.

A filament assembly, comprising:

• a heat sink defining a plurality of slots;
• a plurality of filament segments configured for simultaneous emission of a beam of electrons, wherein a portion of each filament segment is disposed within a corresponding at least one of the slots, and wherein each filament segment includes:
• first and second end portions, the end portions being thermally connected to the heat sink;
• and
• a central portion interposed between the first and second end portions.