Anodes for rotary anode x-ray tubes

An anode for use in a rotary anode x-ray tube, comprising:

• a disc having an axis of rotation and comprised of a first metallic material, said disc having a front and a rear face and said first metallic material being of uniform composition and being uninterrupted from said front to said rear face,
• said front face having a substantially unbeveled central region circumjacent said axis and an adjacent annular region which is beveled rearwardly at an acute angle relative to a plane to which said axis of rotation is perpendicular,
• said rearwardly beveled annular region having a surface layer comprised of a second metallic material having a different coefficient of thermal expansion than said first metallic material, said surface layer providing a focal spot surface on which the electron beam of an x-ray tube impinges to produce x-radiation an incident of which is to produce a high temperature gradient in said disc in the region adjacent said front face,
• said rear face having a substantially unbeveled central region circumjacent said axis and an adjacent annular region which is beveled forwardly at an acute angle relative to a plane to which said axis is perpendicular,
• the configuration of said anode for minimizing distortion of said disc due to cyclical occurrence of said high temperature gradient being defined by the equation ##EQU2## where:
• r.sub.0 is the rear unbeveled surface radius;
• r.sub.1 is the front unbeveled surface radius;
• r.sub.2 is the total anode radius;
• W = T-E where T is the total thickness of the anode and E is the thickness of the peripheral edge of the anode;
• .theta. is the angle between the front rearwardly beveled surface and a plane to which said axis of rotation is perpendicular;
• and
• .phi. is the angle between the rear forwardly beveled surface and a plane to which said axis of rotation is perpendicular.