US1603700A - X-ray-tube regulator - Google Patents

Description

A N LUCIAN X-RAY TUBE REGUQATOR Filed Obt. '11. 1920 Oct. 19 1926.

Patented Oct. 19, 1-926.

UNITED STATES ARSENE N. LUCIAN, OF PHILADELPHIA, PENN SYLVAIIIA.

X-RAY-TUBE REGULATOR.

Application filed October 11, 1920. Serial No. 416,089.

This invention relates to X-ray tubes. The object of the invention is to improve both the regulation and the operation of a tube of the gas type.

The proper operation of a tube of this type requires the maintenance of a critical degree of vacuum within the tube. From continuous service the vacuum tends to rise, that is, the pressure within 'thebulb de creases during service and it-is necessary that some means be provided for lowering the vacuum to the critical point necessary for proper operation in order that a continuance in the service of the tube may immediately be bad. This regulation of the vacuum within a tube is accomplished through the medium of a side tube provided with a spark electrode in contact with a gas emitting chemical customarily held in place by means of a stuffing of asbestos. In some instances a packing of abscstos in such a side tube has been employed without other chemical. The passage of sparks from the auxiliary electrode in this side tube causes gas to be emitted not only from the chemical charge but also from the asbestos packing which escapes into the interior of the bulb to lower the vacuum. It has been found that, when asbestos has been employed to keep the chem ical charge in place, that the emitted gas is for the most part injurious to an X-ray tube as it contains a number of impurities particularly organic vapors and oxygen developed from the asbestos. Ideally that particular gas alone should be employed for reducing the vacuum after a continuous run of a tube which gas is the same as that formin the attenuated atmosphere within the bu b proper.

It is an object of my invention to provide a regulator which upon proper excitation will supply the desired quantity of only the desired gas which alone may enter the bulb proper to regulate'the vacuum and I contemplate the provision of means which shall revent the loosening of any impurities durmg the regulating operation or at any time. A further object of'my invention is to improve the general structure of a tube, as to the mounting of the electrodes and the provision of a self contained valve to facilitate the operation of the tube in response to non-uni-directional potential impulses.

The above will better be understood by reference to the illustrative embodiments described in the following specification in conwith parts shown in elevation of an illus- .trative embodiment of my invention;

Fig. 2 is a detail section drawn to an enlarged scale of my regulator structure; and

Fig. 3 is a similar view showing a modification of my regulator structure.

A is a glass bulb of usual construction having opposite aligned electrode extensions 1 and 2. Sealedto the far end of extensipn l is an inner glass sleeve 3 mounting the pinch slip-sleeve 4 of cathode 5 which has a substantial metallic stem 6, extending outwardly within the sleeve 3 and is connected with the terminal electrode 7. The sleeve 3 is preferably provided with vents 8.

Sealed to the extension 1, preferably some what inward from its outer end but near its outer end, is a glass sleeve 9 which projects inwardly towards the interior of bulb A and is provided with a bulbous enlargement 10 having ,vents 11 near the mouth of the extension 1. The sleeve 9 terminates in a throat 12 having bosses 13 cooperating with perforations 1 1, in the slotted metal mounting sleeve 15 for anode 16. The anode 16 being mounted upon the last sleeve 15 is therefore electrically insulated so far as con duction is concerned from all other parts of the tube.

An auxiliary electrode, which may be identical in construction with the cathode 5 and symmetrically positioned with respect thereto, is indicated by 17, which has an outwardly extending substantial sized metal stem 18 extending within the glass sleeve 19 which is sealed to the outer end of extension 1 and is connected with the anode terminal 20.

The sleeve 19, like the sleeve 3 may have vents 21. The auxiliary electrode 17, cooperatingwith the rear 22 of anode 16 serves as a direction valve for the entire tube and the bulbous enlargement 10 localizes the valve action so that no interference with the X-ray generation of the tube is permitted. Heretofore it has been customary to connect a valve tube in series with the ordinary. I

X-ray tube for the purpose of suppressing inverse, but with my construction. the valve and the X-ray tube are eonibined'within one bulb so that a saving is accomplished. In my tube the X-ray' anode serves the additional function of an electrode for the valve formed between itself and the electrode 17.

For regulating the vacuum within the tube the usual side tube B is provided, in the outer end of which is sealed mounting glass sleeve 30 which mounts the split expansion metallic sleeve 31 connected with the spark terminal 32. The sleeve 31 is preferably spun. out into a collar 33 serving as a shoulder mounting for the metallic pan 3% which has a flange 35 serving to grip the vitreous porous thimble 36. In the embodiment shown in Fig. l the flange 35 directly grips the rim of the thimble 36, whereas in Fig. 2 it is shown secured thereto by a suitable vitreous cement 37 such as alundum paste. Projecting through the pan 34 into the interior of the thimble 36 is electrode 38, preferably provided with a number of flaring wires or fingers 39 projecting into the chemical charge 4:0. In Fig. 3 the pan 41 corresponding to the pan 34 has a spring flange 4E2, tending to expand and frictiona'lly engage the inner surface of the rim of the thimble 36. is a conducting Wire sealed tight in thimble 36.

I prefer to construct my thimble 36 out of some highly porous earthen material which itself is free from gases and which under electric excitation will not decompose into gas. I prefer that the material be highly refractory and that it be impervious to the passage of all solid material but shall permit the passage through its walls of gas which may be generated by the chemical charge 40 within its cavity. I have found that unglazed porcelain, alundum and carborundum are satisfactory materials for the construction of the porous thimble, 36. The chemical charge L0 may consist of any chemical capable under electric excitation of liberating the gas desired for the atmosphere within the bulb A. Examples for the liberation of nitrogen areiron-nitride, aluminum-nitride and calcium-nitride and for the liberation of carbondioxideferrous oxalate, ferrous carbonate and manganesium carbonate. The charge 40 is completely enclosed so that no loose particles may be driven out into the bulb A although the generated gas may freely pass through the porous walls of the thimble. Although this porous structure is shown in the form of a thimble, porous throughout, I contemplate that every portion thereof so functions. The side walls -13 are in the form of a sleeve which is insulating, refractory and porous and which serves as a protector for the electrode 38. I believe that the use of such a sleeve is broadly new. I also understand that the end Wall 44 of my thimble may be regarded as the sole functioning porous wall of my structure.

In other words, functionally, I contemplate the complete enclosure of the gas emitting charge of chemical by an enclosure at least a portion of the walls of which are porous to the passage of the desired gas but impervlous. to the passage of undesirable substances during the regulation of the tube and in fact at all times.

What I claim and desire to secure by U. S. Letters Patent is:

1. An X-ray tube having a vacuum regulator comprising an auxiliary terminal; a charge capable of emitting a gas under excitation from said terminal and located at the end of said terminal in communication with a cavity of said X-ray tube; anda structure completely out of contact with the glass walls of said tube and completely enclosing said charge and having a solid Wall of porous material dividing said charge from the cavity of said X-ray tube.

2. In an X-ray tube, an electrode and a hollow cylindrical sleeve of solid insulating porous material cooperating with said electrode and permitting the assage of gas therethrough but insulating fioth to the passage of electricity and of solid particles.

3. A regulator for X-ray tubes comprising a porous thimble of insulating refractory material; a gas emitting chemical within said thimble; an electrode in cooperative relation to said chemical to excite the same to emit gas; and means for completing with said thimble a complete enclosure about said chemical.

In witness whereof I have signed my name to this specification this 20th day of August, 1920.

ARSENE N. LUCIAN.

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