US2149093A - Method and apparatus for X-ray production - Google Patents

Method and apparatus for X-ray production Download PDF

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Publication number
US2149093A
US2149093A US147287A US14728737A US2149093A US 2149093 A US2149093 A US 2149093A US 147287 A US147287 A US 147287A US 14728737 A US14728737 A US 14728737A US 2149093 A US2149093 A US 2149093A
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US
United States
Prior art keywords
discharge
cathode
anode
ray
condenser
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US147287A
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English (en)
Inventor
Kenneth H Kingdon
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co
Original Assignee
General Electric Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to BE429452D priority Critical patent/BE429452A/xx
Application filed by General Electric Co filed Critical General Electric Co
Priority to US147287A priority patent/US2149093A/en
Priority to FR838991D priority patent/FR838991A/fr
Priority to GB17188/38A priority patent/GB499721A/en
Priority to DE1938A0087101 priority patent/DE693547C/de
Application granted granted Critical
Publication of US2149093A publication Critical patent/US2149093A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/22—X-ray tubes specially designed for passing a very high current for a very short time, e.g. for flash operation
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05G—X-RAY TECHNIQUE
    • H05G1/00—X-ray apparatus involving X-ray tubes; Circuits therefor
    • H05G1/08—Electrical details
    • H05G1/10—Power supply arrangements for feeding the X-ray tube
    • H05G1/22—Power supply arrangements for feeding the X-ray tube with single pulses
    • H05G1/24—Obtaining pulses by using energy storage devices

Definitions

  • the present invention relates to improvements in methods and means for producing X-rays and related radiations.
  • this is accomplished by utilizing as an X-ray source a discharge device having a cathode of a type which is capable of generating almost unlimited quantitles of electron emission.
  • a cathode comprises a body or pool of mercury.
  • a discharge device of the class in question may, under certain conditions and for at least short intervals of time, be operated in such a manner as to realize potentials of X-ray-producing-magnitude in the discharge space and to provide X-ray-producing currents of extremely large magnitudes. Specifically, this is accomplished in a preferred embodiment of the invention by the provision of high potential energy storage means capable of supplying extremely high-intensity current to a pool-type discharge device during an initial discharge period.
  • Fig. 1 represents a discharge device suitable for the practice of the invention in combination with an appropriate circuit for energizing the same
  • Fig. 2 is a graphical representation useful in explaining the invention
  • Fig. 5 is a sectional view of an alternative form 01. discharge device in connection with which the invention may be applied.
  • I have shown I lo a discharge device comprising an elongated glass envelope III which encloses a plurality of cooperating discharge electrodes including an anode,
  • the anode, indicated at H may suitably comprise a plate or disk capable of X-ray emission upon bombardment by high velocity electrons. It is preferably constituted of a refractory metal such, for example, as tungsten and may be supported within the tube by a conducting member H, for example, of molybdenum.
  • the cathode indicated at I4 is of such nature as to be capable in its normal or steady-state operation of developing electrons at a sufficient rate to permit substantially unlimited energy to be transmitted through the dis- 1 charge device.
  • a cathode is typically exemplified by a pool or other self-reconstructing body of a readily vaporizable ionizable material, such as mercury.
  • discharge devices of the U class described While they are capable of transmitting substantially unlimited energy, as previously specified, they inherently operate at low (non-X-ray-producing) potentials. Such operation is a result of the fact that in a steady- 25 state or non-transient condition sufllcient of the cathode material becomes vaporized'to permit the occurrence of substantial ionization in the discharge space. Such ionization neutralizes space charge and permits the passage of a discharge 30 at potentials on the order of those which characterize an arc. Because of the apparent impossibility of developing high electron velocities within such devices, it has heretofore been considered impracticable to generate X-rays by 35 their use.
  • this condenser may be charged to an X-ray producing potential by means of a high voltage transformer l8 in combination with a rectifier i8 and a current-limiting resistor 20.
  • the rectiller is may be of any known type, for example, a thermionic vacuum tube.
  • a starting electrode 22 suitably comprising a body of semiconducting material having a portion thereof in contact with the cathode during the normal operation of the device. If this electrode is sub- Jected to a properly directed potential at a time when the anode II is positive with respect to the cathode i 4 a discharge will be caused to take place between the anode and cathode.
  • Particular means for impressing such a potential are illustrated as comprising a condenser 23 in combination with a battery 24 for charging the same and a current-limiting resistor 25.
  • a manually operable switch 21 controlling the electrode 22 makes it possible to initiate the discharge at desired intervals.
  • the condenser I! be of relatively high capacity and capable of being charged to X-ray-producing potentials. (In a particular case I have employed with good success a condenser having a capacity of 0.015 microfarad and charged to an operating potential of 100,000 volts.) It is also necessary that the circuit connections 29 and 30, which connect the condenser to the anode and cathode terminals of the discharge device, be of extremely low inductance and resistance in order that they shall not constitute a limitation on the rate at which current may be delivered to the discharge device. In connection with the discharge device itself, it is desirable to have the surface of the electrodes clean and free from contaminating impurities which might tend to modify the breakdown characteristics of the device.
  • Fig. 2 The precise character of the variations obtained is illustrated in Fig. 2, in which it appears that the amount of X-radiation obtainable with a mercury pool cathode falls oi! rapidly at temperatures above about 0 C. For this reason, I prefer to operate at mercury temperatures below ,this value, and in Fig. 1 I have shown an exemplary means for maintaining the mercury temperature within the desired range. As shown, such means comprises a cooling coil 25 having an inlet 36 and an outlet 21 and arranged in heatexchanging relation with the cathode I4. At zero degrees centigrade the vapor pressure of mercury is about 0.16 micron.
  • the energy storage means is of the same character as that previously described and comprises a condenser 40 adapted to be connected to a high potential source (not shown) through a current-limiting resistor 4
  • the discharge device differs from that previously described in comprising only an anode 43 and a cathode 44, the starting electrode being omitted.
  • a spark gap comprising spaced spheres 46 and 41, such spheres being separated by a distance which permits breakdown between them only upon application of a voltage of X-ray producing magnitude.
  • the device is shunted by a high resistance 48 (say, 50,000 ohms).
  • the spheres 46 and 41 may be maintained in fixed spatial relationship and the voltage across the condenser 40 allowed to build up until breakdown of the spark gap occurs, whereupon substantially the full voltage of the condenser will be impressed across the discharge device.
  • the condenser 40 may be charged to a desired voltage and the spacing of the spheres decreased until a discharge occurs.
  • X-radiation of the character previously described may be obtained provided the rate of current supply to the discharge device during its initial discharge period is sufliciently great.
  • a spark gap 50 is included in the circuit connections between the energy storage means and the discharge device.
  • a portion of the voltage will exist across the spark gap and another portion across the discharge space between the anode II and the cathode I4. 7
  • the starting electrode 22 is energized, however, the decrease in the drop across the discharge space will raise the potential gradient across the spark gap and result in its immediate breakdown.
  • Fig. 5 I have shown another form of discharge device which may be substituted for that described in connection with Fig, 1.
  • an elongated glass envelope 55 which is closed at its ends by means of metal members 56 and 51 sealed into the glass.
  • the upper metal closure member acts as a support for an anode 58 to which it is connected by means of a conducting structure including shaft portions 60 and GI. These two shaft portions are connected by means of a conducting cylinder 62 which is of a diameter only slightly smaller than that of the envelope itself and which provides a long narrow space between the cylinder and the envelope whereby the possibility of a discharge reaching the closure member 56 may be effectively avoided.
  • the lower closure member 5! acts as a receptacle for a quantity of cathode material 64, suitably of mercury, and is provided externally with cooling means in the form of a cooling coil 65 as previously described.
  • a starting electrode 66 comprising a tapered body of semi-conducting material.
  • a metal shield 68 interposed between them.
  • the shield 68 is preferably provided with a rounded and polished surface whereby the danger of its acting as a point of breakdown is reduced to a minimum.
  • cathodes comprising these materials are generically referred to herein and in the following claims as "pool-type cathodes", by which term I intend to designate a pool or other substantial body of the materials in question.
  • a source of a readily ionizable gas This may comprise either a vaporized component of the cathode material itself, or a residual gas such as argon provided in the discharge envelope.
  • a discharge device comprising an anode constituted of a material which is capable of effective X-ray emission upon bombardment by high potential electrons and a pooltype cathode serving as a source of ionizable vapor, a condenser, circuit means for connecting the condenser to the anode and cathode terminals of the discharge device, said circuit means having a substantially negligible impedance during discharge periods of the device, and means effective during inoperative periods of the device to charge such condenser to an X-ray producing potential.
  • a discharge device comprising an anode constituted of a material which is capable of effective X-ray emission upon bombardment by high velocity electrons and a pool type cathode cooperatively associated with the anode, said cathode being capable in its normal or steady state operation of developing electrons at a suflicient rate to permit substantially unlimited current to be transmitted between the anode and cathode at non-X-ray-producing potentials, a condenser, circuit means for connecting the condenser to the anode and cathode terminals of the discharge device, said circuit means having a substantially negligible impedance during discharge periods of the device, means effective during inoperative periods of the device to charge such condenser to an X-ray producing potential, and means for initiating a discharge through the device at desired intervals.
  • a discharge device enclosing an anode and a mercury pool cathode, means for cooling said cathode sufliciently to maintain the normal vapor pressure in the envelope below about 0.16 micron of mercury, a condenser, circuit means for connecting the condenser to the anode and cathode terminals of the discharge device, said circuit means having a substantially negligible impedance during discharge periods of the device, means effective during inoperative periods of the device to charge such condenser to an X-ray producing potential, and means for initiating a. discharge through the device at desired intervals.

Landscapes

  • X-Ray Techniques (AREA)
  • Exposure Of Semiconductors, Excluding Electron Or Ion Beam Exposure (AREA)
US147287A 1937-06-09 1937-06-09 Method and apparatus for X-ray production Expired - Lifetime US2149093A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
BE429452D BE429452A (fr) 1937-06-09
US147287A US2149093A (en) 1937-06-09 1937-06-09 Method and apparatus for X-ray production
FR838991D FR838991A (fr) 1937-06-09 1938-06-08 Perfectionnements aux tubes à décharge
GB17188/38A GB499721A (en) 1937-06-09 1938-06-09 Improvements in and relating to methods of and apparatus for for the production of x-rays
DE1938A0087101 DE693547C (de) 1937-06-09 1938-06-10 Roentgenroehrenanordnung

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US147287A US2149093A (en) 1937-06-09 1937-06-09 Method and apparatus for X-ray production

Publications (1)

Publication Number Publication Date
US2149093A true US2149093A (en) 1939-02-28

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ID=22520978

Family Applications (1)

Application Number Title Priority Date Filing Date
US147287A Expired - Lifetime US2149093A (en) 1937-06-09 1937-06-09 Method and apparatus for X-ray production

Country Status (5)

Country Link
US (1) US2149093A (fr)
BE (1) BE429452A (fr)
DE (1) DE693547C (fr)
FR (1) FR838991A (fr)
GB (1) GB499721A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2623191A (en) * 1947-03-20 1952-12-23 Int Standard Electric Corp Electric discharge tube

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2623191A (en) * 1947-03-20 1952-12-23 Int Standard Electric Corp Electric discharge tube

Also Published As

Publication number Publication date
GB499721A (en) 1939-01-27
FR838991A (fr) 1939-03-21
DE693547C (de) 1940-07-13
BE429452A (fr)

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