Angled flat emitter for high power cathode with electrostatic emission control

A method for focusing an electron beam emitted from an X-ray tube, the method comprising the steps of:

• providing an X-ray tube including a cathode assembly on which is disposed a pair of emission surfaces for generating a pair of electron beams, the pair of emission surfaces disposed at an angle with regard to one another, a focusing electrode adjacent the cathode assembly, an extraction electrode spaced from the focusing electrode opposite the cathode assembly that can be can be adjusted between a positive and negative bias relative to the pair of emission surfaces, a magnetic assembly spaced from the extraction electrode opposite the focusing electrode and a target spaced from the magnetic assembly opposite the extraction electrode capable of generating X-rays when impinged upon by the electron beams;
• passing an emission current through at least one of the pair of emission surfaces to generate an electron beam;
• and
• passing a focusing current through the magnetic assembly to focus the electron beam onto the target.

A computed tomography system comprising:

• a gantry;
• an X-ray tube coupled to the gantry, the X-ray tube comprising a cathode assembly having a pair of emission surfaces for generating an electron beam, the pair of emission surfaces disposed therein at angles with respect to one another, a focusing electrode for focusing the electron beam, and an extraction electrode which controls the intensity of the electron beam though the adjustment of a positive or negative biasing voltage applied to the extraction electrode;
• and
• a target for generating X-rays when impinged upon by the electron beam.