Radiation generating tube

摘要

The present invention provides a radiation generating tube which suppresses electrical charging of an inner wall of an insulating tube attributable to electron emission from a junction between the insulating tube and a cathode and which has improved voltage withstand capability. The radiation generating tube comprising: a hollow insulating tube; a cathode and an anode respectively bonded to both ends of the insulating tube; and an electron emission source provided on the cathode, the radiation generating tube having a vacuum interior space. The electron emission source includes an electron emitting portion in the interior space, and the insulating tube includes a protrusion that protrudes into the interior space.

主权项

1. An X-ray generating tube comprising:
a hollow insulating tube having an inner wall; a cathode and an anode respectively bonded to first and second ends of said insulating tube; and an electron emission source provided on said cathode, said X-ray generating tube having a vacuum interior space that is enclosed by said insulating tube, said cathode, and said anode, wherein
said electron emission source includes an electron emitting portion in said interior space and has a tip, andsaid insulating tube includes a protrusion that protrudes into said interior space,whereinwhen a distance in an axial direction from said cathode to said tip of said electron emission source is denoted by L1 and a distance in a radial direction between said electron emission source and said inner wall of said insulating tube at said tip of said electron emission source is denoted by D,a distance of closest approach R (L) between said electron emission source and said protrusion arranged at a position at a distance of L in the axial direction from said cathode satisfies the following relationship:
R(L)≧D×L/L1, andwhereinsaid inner wall of said insulating tube is formed of a cylindrical surface, said protrusion is a protruding portion that protrudes inward in the radial direction from said inner wall of said insulating tube, andan amount of protrusion H (L) of said protruding portion from said inner wall satisfies the following relationships:where L≦L1:
H(L)≦(1−L/L1)×D, andwhere L>L1:
(D−H(L))2+(L−L1)2≧(D×L/L1)2.