US3617788A - Method of vacuum-tight closure of thin beryllium windows and x-ray tube provided with such a window - Google Patents

Method of vacuum-tight closure of thin beryllium windows and x-ray tube provided with such a window Download PDF

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Publication number
US3617788A
US3617788A US856647A US3617788DA US3617788A US 3617788 A US3617788 A US 3617788A US 856647 A US856647 A US 856647A US 3617788D A US3617788D A US 3617788DA US 3617788 A US3617788 A US 3617788A
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United States
Prior art keywords
window
beryllium
windows
ray tube
vacuum
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Expired - Lifetime
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US856647A
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English (en)
Inventor
Jan Goorissen
Pieter Van Der Werf
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US Philips Corp
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US Philips Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J35/00—X-ray tubes
    • H01J35/02—Details
    • H01J35/16—Vessels; Containers; Shields associated therewith
    • H01J35/18—Windows
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2235/00—X-ray tubes
    • H01J2235/18—Windows, e.g. for X-ray transmission
    • H01J2235/183—Multi-layer structures

Definitions

  • the practically unavoidable pores or cracks in the beryllium foil are found to be completely closed by a layer thickness of about 1 t.
  • rejects in the production due to bad vacuum-tightness can be avoided and it becomes thus possible to manufacture reliable X-ray tubes provided with these extremely thin windows.
  • window plates cut from such metal foil and arranged in the window frame are often not vacuum-tight and hence unserviceable. Reinsertion of a window involves additional time and costs. This is not readily avoidable because a preliminary test of cutout window plates for assessing the vacuum-tightness does not always give reliable results. It is furthermore unavoidable that a piece of metal foil of comparatively small size, having many pores, is divided among a plurality of windows during cutting, which are then unserviceable.
  • the invention relates to a method of vacuum-tight closure of beryllium windows of a thickness of not more than 100 ,u. for closing exit openings of X-ray tubes and has for its object to obviate said disadvantages.
  • the mechanically machined window cut from a thin, rolled plate of beryllium is provided by a particle sputtering technique with a covering layer closing the pores of the window.
  • a coating of a thickness of about I 41 applied to a beryllium window by sputtering provides a complete closure of the pores provided these pores do not exceed about 1..
  • the material to be sputtered should for this purpose contain only elements of a low atomic number and usually consists of beryllium oxide or beryllium.
  • the rolled beryllium foil may be treated before cutting window plates.
  • the cutout window plates may be treated separately, while the use of material of apparently bad portions of a metal foil can be avoided.
  • the windows already arranged in a frame may be treated, which facilitates handling and checking with respect to vacuum-tightness.
  • the treatment may be carried out after the windows, which may no longer be flat but be provided with some profile for special requirements, have been arranged in the window opening of the X-ray tube.
  • FIG. I is a quite schematic sectional view of a device for carrying out the method
  • FIG. 2 is a sectional view of an X-ray tube provided with a window in accordance with the invention.
  • the sputtering space 1 communicates through an opening 2 in a base plate 3 with a suction pump (not shown), while the space 1 is bounded by a bell 4, preferably of glass.
  • the sputtering space accommodates a metal electrode 5, to which a beryllium oxide plate 6 is fastened
  • the electrode 5 together with the plate 6 is electrically connected via a through-connection 7 to a high-frequency generator 8, which is capable of supplying a voltage up to 4 kv. of a frequency of 20 MHz.
  • the electrode 5 and the supply conductor 9 inside the bell are screened by an earth-con nected sheath 10.
  • a vapor-deposition table 11, electrically connected to a base plate, can receive the beryllium windows to be treated.
  • the base plate has the further required passages,
  • the passage 12 for the supply of ar on as to the sputtering space 1 being shown.
  • a control v ve 2 the pressure of the argon gas can be adjusted in the space 1.
  • This gas pressure is of the order of 5X10 Torr.
  • the high-frequency field applied, together with a magnetic field produced by a magnet coil 14, produces a plasma of argon ions and maintains it so that particles are released from the beryllium oxide plate 6 and applied to the window 15 lying on the table 11.
  • the thickness of the coating is controlled by the duration of the process and is about 1 u.
  • the plate 6 must be replaced by a plate of beryllium metal, in which case a capacitor must be connected between the electrode 5 and the high frequency source in order to cause the process to be performed in the correct sense. It is furthermore possible to volatilize beryllium in an oxygen atmosphere, so that a coating of beryllium oxide is formed. If the window plate is to be treated after mounting in the X-ray tube, an opening (not shown) has to be provided in the bell or in the base plate, through which the window can be disposed approximately at the place of the then failing table 11. The tube to be treated must then be conductively connected to the base plate.
  • FIG. 2 One embodiment of an X-ray tube comprising a window thus treated is shown in FIG. 2.
  • This tube is of the type disclosed by the applicant in Dutch Pat. application No. 6,708,463, where the desirability of thin windows is indicated and the problem of lack of vacuum-tightness of these windows is involved.
  • the tube comprises a glass sheath 20 enclosing a vacuum space in which a cathode 21 is arranged, opposite which a hollow metal tube 22 is arranged, which extends beyond a seal 23 of the sheath 20 and is made of ferromagnetic material, for example, iron.
  • this tube accommodates a copper anode 24, which closes the tube in an airtight manner, while the window 25 of a thickness of, for example, 50 [-L is located opposite said anode in the wall of the tube through which window the X-rays released at 26 emerge.
  • the projecting tube portion may be arranged in the bell of FIG. 1. The small quantity of beryllium or beryllium oxide deposited on the tube wall during treatment will not give rise to any difficulty. If desired, the tube may be screened against it.
  • a method of hermetically sealing beryllium windows of a thickness of less than ,u for closing radiation openings of X-ray tubes comprising the step of sputtering beryllium or beryllium oxide onto a thin rolled sheet of beryllium to form a coating thereon closing the pores in the beryllium sheet.
  • window plates are cut from a foil and are fastened in a frame readily mounted in the exit opening of an X-ray tube, said plates then being provided with a coating on at least one side thereof.
  • An X-ray tube for producing comparatively soft X-rays for fluorescence analysis of elements of a low atomic number comprising an evacuated envelope provided with anode and cathode electrodes, said envelope having a beryllium exit window having a thickness of about 50 11., said window provided on at least one side with a sputtered coating of beryllium or beryllium oxide closing the pores in the window.

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  • Analysing Materials By The Use Of Radiation (AREA)
  • X-Ray Techniques (AREA)
  • Physical Vapour Deposition (AREA)
US856647A 1968-09-14 1969-09-10 Method of vacuum-tight closure of thin beryllium windows and x-ray tube provided with such a window Expired - Lifetime US3617788A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL6813190A NL6813190A (enrdf_load_stackoverflow) 1968-09-14 1968-09-14

Publications (1)

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US3617788A true US3617788A (en) 1971-11-02

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US856647A Expired - Lifetime US3617788A (en) 1968-09-14 1969-09-10 Method of vacuum-tight closure of thin beryllium windows and x-ray tube provided with such a window

Country Status (6)

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US (1) US3617788A (enrdf_load_stackoverflow)
AT (1) AT294263B (enrdf_load_stackoverflow)
DE (1) DE1942922A1 (enrdf_load_stackoverflow)
FR (1) FR2018139A1 (enrdf_load_stackoverflow)
GB (1) GB1232125A (enrdf_load_stackoverflow)
NL (1) NL6813190A (enrdf_load_stackoverflow)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4178509A (en) * 1978-06-02 1979-12-11 The Bendix Corporation Sensitivity proportional counter window
US4566116A (en) * 1982-04-30 1986-01-21 Hitachi, Ltd. Soft X-ray generator
US5013922A (en) * 1990-03-13 1991-05-07 General Electric Company Reduced thickness radiation window for an ionization detector
US5418830A (en) * 1992-05-15 1995-05-23 Scan-Tech S.A. Radiometric thickness measurement gage
EP0757362A1 (de) * 1995-08-02 1997-02-05 INSTITUT FÜR MIKROTECHNIK MAINZ GmbH Röntgenstrahlendurchlässiges Schichtmaterial, Verfahren zu seiner Herstellung sowie deren Verwendung
US20070291901A1 (en) * 2006-06-15 2007-12-20 Varian Medical Systems Technologies, Inc. X-ray tube window bonding with smooth bonding surface

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2663812A (en) * 1950-03-04 1953-12-22 Philips Lab Inc X-ray tube window
US2866114A (en) * 1953-06-12 1958-12-23 Philips Corp Beryllium window x-ray tube

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2663812A (en) * 1950-03-04 1953-12-22 Philips Lab Inc X-ray tube window
US2866114A (en) * 1953-06-12 1958-12-23 Philips Corp Beryllium window x-ray tube

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4178509A (en) * 1978-06-02 1979-12-11 The Bendix Corporation Sensitivity proportional counter window
US4566116A (en) * 1982-04-30 1986-01-21 Hitachi, Ltd. Soft X-ray generator
US5013922A (en) * 1990-03-13 1991-05-07 General Electric Company Reduced thickness radiation window for an ionization detector
US5418830A (en) * 1992-05-15 1995-05-23 Scan-Tech S.A. Radiometric thickness measurement gage
EP0757362A1 (de) * 1995-08-02 1997-02-05 INSTITUT FÜR MIKROTECHNIK MAINZ GmbH Röntgenstrahlendurchlässiges Schichtmaterial, Verfahren zu seiner Herstellung sowie deren Verwendung
US5740228A (en) * 1995-08-02 1998-04-14 Institut Fur Mikrotechnik Mainz Gmbh X-ray radiolucent material, method for its manufacture, and its use
US20070291901A1 (en) * 2006-06-15 2007-12-20 Varian Medical Systems Technologies, Inc. X-ray tube window bonding with smooth bonding surface

Also Published As

Publication number Publication date
GB1232125A (enrdf_load_stackoverflow) 1971-05-19
NL6813190A (enrdf_load_stackoverflow) 1970-03-17
AT294263B (de) 1971-11-10
FR2018139A1 (enrdf_load_stackoverflow) 1970-05-29
DE1942922A1 (de) 1970-03-19

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