US1092489A - X-ray tube. - Google Patents

Description

. KESSELRING.

X-RAYTUBB.

APPLICATION FILED OCT. 17. 1912.

Patented Apr. 7, 1914 E il, rrr il HERMANN 1VI. KESSELRING, OF CHICAGO, ILLINOIS.

X-RAY TUBE.

' Specification of Letters Patent.

Patented Apr. 7, 1914.

Application filed October 17, 1912. Serial No. 726,230.

l of whichthe following is a specication.

In the use of X-ray tubes, as hitherto constructed, they frequentlypuncture at points adjacent to the electrodes, and more especially at or near the junction of the body and handle portions at the cathode side of the tube. The primary cause of this puncturing is that the surfaceportions of the metal electrode become oxidized and metal oXid particles are deposited upon the sur- `face of the glass. When a particle of metal loXid lodges upon the glass at a point near the cathode, more especially, the current is apt to jump from the cathode to such parti` cle causing a spark which punctures the glass at that point and destroys the usefulness of the tube.

. My object is so to improve the construc- `tion of X-ray tubes as to obviate or, at least, greatly diminish the said danger.

It is further my object to provide means for the rapid withdrawal of heat from the body of the tube, to prevent overheating thereof and thus render it easier to handle with less liability of injury to the tube.

The accompanying drawing is a sectional view of an X-ray tube, of known 'construction, provided with my improvements.

The tube is of glass having the usual spherical body-portion 1, and the hollow eX- tensions 2, 3 forming handles. In the eXtension 2 is a cathode 4 formed with a head, having a concave face 5, and a stem 6.

The numeral 7 designates the target which serves likewise as the main anode of the tube. The stem 8 of the anodeis in the eX- tension 3. On the body-portion is the usual regulator 9 and also a hollow extension 10, containing an assistant anode 11.

Supported in the part 2 is an insulating shield 12, preferably of lead-glass. The shield 12 surrounds the stem and head of the cathode leaving only the concave face 5 thereof exposed. The shield 12 is out of contact With the stem 6 of the cathode eX- cept at the point 13 where it is contracted about the same to steady it. The shield 12, being of lead-glass, by which I mean glass having a material percentage of lead in its composition, is impervious to cathode rays and operates as a current insulator serving to confine the discharge of current to the concave face 5, and squarely against the target 7, thereby limiting dissemination of the cathode rays in the tube. The shield 12 also serves as a heat-insulator for the cathode which protects the extension 2 and adj acent body-portion 1 from the heat generated at the cathode.

The anode or target 7 is a solid cylindrical metal block with an inclined face containing a platinum disk 14. Surrounding the target is a metal sleeve 15 having an opening 16 through which the X-rays are projected.

Within and integral with the extension 3 is a preferably lead-glass shield formed with an inner-tubular portion 17 loosely surrounding the stem 8 and attached by the metal sleeve or ferrule 18 to the cylindrical head 7. Integral with the inner sleeve 17 is an outer lead-glass sleeve or tube 19 surrounding the parts 17, 18 and 15, and eX- tending slightly beyond the latter. It has an opening 20 registering with the opening -16. The inner and outer sleeves or tubes 17, 19, serve as current and heat-insulators for the head and stem of the anode and protect the surrounding extension 3 and adjacent body-portion 1 from the heat of the anode. The outer-end portion ofthe eXtension 3 is enlarged into a bulb 22, and is of thinner glass than the body-portion of the tube. The glass being thinner permits heat to discharge or radiate therefrom more rapidly, and in practice much of the heat genlerated at the anode is conducted, along the parts 7, 8, 18, 17 and 19 to the thin glass bulb 22 whence it radiates rapidly into the surrounding atmosphere. The bulb 22, in practice, serves in factto withdraw much of the .heat from the main bulb, or body-portion, 1 and thus diminish danger of injury to the tube in the handling thereof.

The assistant anode 11 is loosely surrounded, in the part or extension 10 of the tube by a, preferably lead-glass, tube, or shield, 21, integral with the part 10 and serving as a current and heat-insulator.

While the tube is in operation the cathode 4, more especially, becomes heated to a high temperature and the main purpose of the shield 12 is to reduce the heat radiated therefrom to the extension 2 and adjacent bodyportion 1 of the tube. It has been found in practice that if the latter become heated to a high temperature 'they are very apt to fracture if touched with metal or any comparatively cold object. Furthermore, heating, particularly, of the extension 2, interferes with the handling of the tube by the operator. The shield 12 absorbs much of the heat radiated from lthe cathode and thus serves to prevent the surrounding tube from being heated to a degree which will cause it to fracture and puncture, if touched with metal, as by a ring onr the operators finger, and also prevents the extension 2 from being heatedl to a temperature which Willinterfere with ready handling thereof by the operator. The inner and outer tubes or shields 17, 19 serve to insulate the target or anode and to protect the surrounding parts 3 and 1 of the tube from theheat thereof. The shields 17, 19, furthermore, serve to prevent metal oxid loosened from the anode from being deposited against adjacent parts j the inner surface of the handle or body-portion near enough to the cathode for the current to spark, across. This s arking against' the glass of the handle or bo y-portlon is apt to, and frequently does, result in puncturing the lass thereby destroying the usefulness of t e tube. When the particles of metal oxid remain in the shield .12, the current may jump thereto and cause sparks, but as .the shield is very hot and not exposed to the chilling effect of the outside. atmosphere, it is not liable to puncture, though if it did puncture, it would Anot destroy the usefulness of the tube. Incidentally the leadv lass shields described reduce danger of -ray burns the handling of the implement.

The foregoing description is intended to convey a clear understandin of my improvements in what I nonT believe to be the best form of their embodiment, and-no undue limitation should be understood therefrom. It is my intention to claim all that is novel in my invention, andthat the claims shall be construed as broadly as the prior state of the art may Warrant.

What I claim as new and desire to secure by Letters Patent is 1. lIn an X-ray tube, the combination with the glass body-portion and electrodes, of a glass extension containing one of the electrodes and formed along its outer-end portion with a compartment of thinner glass than the said body-portion, for the purpose set forth.

2. In an X-ray tube, the combination vvitl.` the glass body-portion and electrodes, of a glass extension having an enlarged outerend portion forming a compartment of thinner glass than the said body-portion, for the purpose set forth. A

HERMANN M. KESSELRING.

L. I-IEIsLAR, J. LANDEsMAN.

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