Rotary piston x-ray tube with the anode in a radially rotating section of the piston shell
A rotary piston x-ray tube has a piston formed by a case wall and support such that it can rotate around a rotational axis. The piston contains a cathode and an anode. To improve cooling, the anode of the rotary piston x-ray tube forms a radially-rotating section of the shell wall.
1. A rotary piston x-ray tube comprising:
a rotary piston comprising a first piston base and a second piston base and a continuous shell wall extending between and connecting said first piston base and said second piston base, said shell wall having a frustrum-shape with a region of maximum radius;
said rotary piston enclosing an evacuated volume and containing an anode and a cathode in said evacuated volume, said cathode emitting an electron beam;
said rotary piston being supported for rotation around a rotational axis and said anode forming a radially-rotating section of said shell wall disposed in said region of maximum radius;
a deflector disposed along said shell wall between said cathode and said anode, said deflector interacting with said electron beam to deflect said electron beam from said cathode onto said anode, said electron beam striking said anode and causing emission of x-rays from said anode as well as generation of heat at said anode; and
said shell wall having an exterior surface at said region of maximum radius that is exposed to allow direct interaction of said exterior surface with a coolant, said exterior surface being in thermal communication with said anode and promoting transfer of said heat from said anode to said coolant.
2. A rotary piston x-ray tube as claimed in claim 1 wherein said shell wall comprises a cylindrical region adjacent to said frustum-shaped region.
3. A rotary piston x-ray tube as claimed in claim 1 wherein said anode is cylindrical.
4. A rotary piston x-ray tube as claimed in claim 1 wherein said anode has a frustrum shape.
5. A rotary piston x-ray tube as claimed in claim 1 wherein said anode comprises a layer of a material having a high melting point.
6. A rotary piston x-ray tube as claimed in claim 5 wherein said anode additionally comprises an x-ray emissive layer on said layer of a material with a high melting point.
7. A rotary piston x-ray tube as claimed in claim 6 wherein said x-ray emission layer is comprised of a material selected from the group consisting of tungsten, molybdenum and rhenium.
8. A rotary piston x-ray tube as claimed in claim 1 wherein said anode has a thickness in a range between 10 mm to 20 mm.
9. A rotary piston x-ray tube as claimed in claim 8 wherein said anode comprises an x-ray emissive layer having a thickness in a range between 0.5 mm to 1.5 mm.
10. A rotary piston x-ray tube as claimed in claim 1 wherein said shell wall comprises a section comprised of aluminum.
11. A rotary piston x-ray tube as claimed in claim 1 wherein said shell wall is comprised of a non-magnetic material.
12. A rotary piston x-ray tube as claimed in claim 11 wherein said non-magnetic material is selected from the group consisting of aluminum and stainless steel.
13. A rotary piston x-ray tube as claimed in claim 1 wherein said shell wall has a thickness in a range between 1 mm to 3 mm.
14. A rotary piston x-ray tube as claimed in claim 1 wherein said radially-rotating section of said shell wall has a thickness, and wherein said anode occupies only a portion of said thickness.