EP0646283B1 - Electron beam exit window - Google Patents

Electron beam exit window Download PDF

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Publication number
EP0646283B1
EP0646283B1 EP93911733A EP93911733A EP0646283B1 EP 0646283 B1 EP0646283 B1 EP 0646283B1 EP 93911733 A EP93911733 A EP 93911733A EP 93911733 A EP93911733 A EP 93911733A EP 0646283 B1 EP0646283 B1 EP 0646283B1
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EP
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Prior art keywords
frame
metal foil
electron beam
fibre bundles
vacuum
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EP93911733A
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German (de)
French (fr)
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EP0646283A1 (en
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Olaf Roeder
Ulf Seyfert
Siegfried Panzer
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Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
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Fraunhofer Gesellschaft zur Forderung der Angewandten Forschung eV
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J33/00—Discharge tubes with provision for emergence of electrons or ions from the vessel; Lenard tubes
    • H01J33/02—Details
    • H01J33/04—Windows
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J5/00—Details relating to vessels or to leading-in conductors common to two or more basic types of discharge tubes or lamps
    • H01J5/02—Vessels; Containers; Shields associated therewith; Vacuum locks
    • H01J5/18—Windows permeable to X-rays, gamma-rays, or particles

Definitions

  • the invention relates to an electron beam exit window through which the electron beam generated in an evacuated electron beam is led out into a room of higher pressure, preferably at atmospheric pressure.
  • beam exit windows also called Lenard windows
  • Such beam exit windows are mainly used in electron beam systems with which an electron beam process, such as. B. an electron beam polymerization takes place in a room at atmospheric pressure.
  • the electron beam can be generated both as an axial beam and moved over the beam exit window by means of a scanner, and can also be guided through the beam exit window as a band-shaped or flat-shaped electron beam.
  • the simplest versions consist of a thin, gas-impermeable film, which separates the jet generation chamber from the free atmosphere in a vacuum-tight manner.
  • These foils are preferably made of aluminum, titanium or beryllium alloys. When the electron beam passes through, the film is heated due to the inevitable interaction between the electron beam and the film material.
  • the foils have to withstand the pressure difference, but must not be too thick, on the one hand to limit the energy losses of the electron beam to be discharged and on the other hand to limit the amount of power loss that has to be dissipated from the foil, so that the foil heating remains within a temperature tolerable by the foil material ( US-A-3,222,558).
  • a gas flow is used for heat dissipation.
  • the invention has for its object to provide an electron beam exit window of the type mentioned, which does not require a massive water-cooled support structure, has a low power absorption, is particularly suitable for electron beams of relatively low acceleration voltage and is easy to manufacture.
  • the support of the metal foil by the support grid formed from high-temperature fiber bundles and the loading of the fiber bundle on tensile stress allow a cross-sectional minimization of the support grid construction and thus a substantial reduction in beam losses in the beam exit window.
  • the use of carbon fiber bundles for the support grid is particularly advantageous because of the low elastic expansion and the low coefficient of thermal expansion. Ensuring an approximately circular cross-section of the fiber bundle under load takes place, for. B. by twisting the filaments.
  • the use of fiber bundles made of a highly heat-resistant material enables the maintenance of a high temperature gradient over the support grid in the beam direction as well the dissipation of a substantial part of the beam power absorbed in the support grid by heat radiation.
  • a metal foil made of titanium and carbon fiber bundles as a support grid
  • a similar barrier layer can also be expedient on the pressure side of the foil in order to avoid the undesired diffusion of the gaseous contact partners of the metal foil.
  • the fiber bundles form an angle not equal to 90 ° with the fastening frame. Appropriate adaptation of this angle to the window width, the spacing of the fiber bundles from one another and the power density distribution of the electron beam improve the irradiation homogeneity on the moving material to be irradiated.
  • the metal foil can also be cooled on the pressure side in a known manner by a gas flow, preferably in the direction of the fiber bundle.
  • the radiation exit window according to the invention is particularly suitable for relatively low-energy electron beams and a short distance between the beam exit window and the material to be irradiated.
  • the frame 1 and 2 consists of the frame 1 with the opening 2 for the beam exit, the area of which is covered by a support grid 3 consisting of fiber bundles 4 made of carbon.
  • the fiber bundles 4 are firmly anchored in grooves 5 by filling in casting resin 6.
  • On the Frame 1 is glued to the support grid 3 of metal foil 7 made of titanium.
  • the fiber bundles 4 of the support grid 3 are arranged to improve the homogeneity of the radiation at an angle ⁇ ⁇ 90 ° to the leg of the frame 1.
  • the frame 1 has, on the opposite side of the support grid 3, a sealing surface 8 which bears against the electron beam generator (not shown) in a vacuum-tight manner. To limit the tensile stress in the fiber bundles 4, these have a sag h. Under the effect of the applied pressure difference, the metal foil 7 lies against the support grid 3. To ensure an approximately circular shape of the fiber bundles 4, even under the load from the metal foil 7, the fiber bundles 4 are twisted.
  • a barrier layer 12 made of titanium oxide is applied to the metal foil 7 on both sides in order to reduce chemical reactions between the support grid material and the gaseous reaction partners and the metal foil.

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  • Electron Sources, Ion Sources (AREA)
  • Laminated Bodies (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)

Abstract

Owing to their necessary thickness, prior art electron beam exit wimdows (Lenard windows) have a high absorption or require cooling systems and expensive supporting structures. The aim is to provide a window which is easy to make with low absorption which avoids these problems. The beam exit aperture is given a vacuum-tight seal in the prior art manner using a metal foil while on the vacuum side a supporting grid of highly heatproof fibre strands secured in a frame is fitted to bear against it. The electron beam exit window is particularly suitable for relative low electron energies with high power density.

Description

Die Erfindung betrifft ein Elektronenstrahlaustrittsfenster, über das der in einem evakuierten Elektronenstrahler erzeugte Elektronenstrahl in einen Raum höheren Druckes, vorzugsweise an Atmospharendruck, herausgeführt wird. Derartige Strahlaustrittsfenster, auch Lenardfenster genannt, werden hauptsächlich in Elektronenstrahlanlagen verwendet, mit denen ein Elektronenstrahlprozeß, wie z. B. eine Elektronenstrahlpolymerisation, in einem auf Atmosphärendruck befindlichen Raum erfolgt. Dabei kann der Elektronenstrahl sowohl als Axialstrahl erzeugt und mittels Scanner über das Strahlaustrittsfenster bewegt werden als auch als band- oder flächenförmig erzeugter Elektronenstrahl durch das Strahlaustrittsfenster geführt werden.The invention relates to an electron beam exit window through which the electron beam generated in an evacuated electron beam is led out into a room of higher pressure, preferably at atmospheric pressure. Such beam exit windows, also called Lenard windows, are mainly used in electron beam systems with which an electron beam process, such as. B. an electron beam polymerization takes place in a room at atmospheric pressure. The electron beam can be generated both as an axial beam and moved over the beam exit window by means of a scanner, and can also be guided through the beam exit window as a band-shaped or flat-shaped electron beam.

Es sind verschieden gestaltete Einrichtungen zum Austritt von Elektronenstrahlen an freie Atmosphäre bekannt. Die einfachsten Ausführungen bestehen aus einer dünnen, gasundurchlässigen Folie, welche den Strahlerzeugungsraum vakuumdicht von der freien Atmosphäre trennt. Diese Folien sind vorzugsweise aus Aluminium, Titan oder Beryllium-Legierungen. Beim Durchtritt des Elektronenstrahles wird die Folie infolge unvermeidlicher Wechselwirkung zwischen dem Elektronenstrahl und dem Folienwerkstoff erwärmt. Die Folien müssen der Druckdifferenz standhalten, dürfen aber nicht zu dick sein, um einerseits die Energieverluste des auszuschleusenden Elektronenstrahls und andererseits die Höhe der Verlustleistung, die aus der Folie abzuführen ist, zu begrenzen, so daß die Folienerwärmung innerhalb einer vom Folienwerkstoff tolerierbaren Temperatur verbleibt (US-A-3 222 558). Zur Wärmeabführung dient im einfachsten Fall eine Gasströmung.Variously designed devices for the emission of electron beams to a free atmosphere are known. The simplest versions consist of a thin, gas-impermeable film, which separates the jet generation chamber from the free atmosphere in a vacuum-tight manner. These foils are preferably made of aluminum, titanium or beryllium alloys. When the electron beam passes through, the film is heated due to the inevitable interaction between the electron beam and the film material. The foils have to withstand the pressure difference, but must not be too thick, on the one hand to limit the energy losses of the electron beam to be discharged and on the other hand to limit the amount of power loss that has to be dissipated from the foil, so that the foil heating remains within a temperature tolerable by the foil material ( US-A-3,222,558). In the simplest case, a gas flow is used for heat dissipation.

Es ist weiterhin bekannt, mehrere dünne Folien im Abstand in Strahlrichtung hintereinander so anzuordnen, daß einzelne, gegen den Strahlerzeugungsraum und die Atmosphäre abgedichtete Räume entstehen. Durch diese Räume wird ein Kühlgas derart geleitet, daß sich zwischen dem Strahlerzeugungsraum und der Atmosphäre die Druckdifferenz auf die einzelnen Räume aufteilt, indem der mittlere statische Druck von Raum zu Raum zunimmt. Die Summe der Dicken der einzelnen Folien entspricht mindestens der Dicke einer Folie eines Strahlaustrittsfensters mit nur einer Folie (DD-PS 102 511; US-A-3 162 749). Da die minimal mögliche Foliendicke durch die Herstellbarkeit vakuumdichter Folien begrenzt ist, und sich die Absorption der Einzelfolien summiert, liegen hier die Absorptionsverluste sehr hoch, vor allem, wenn mit relativ geringer Beschleunigungsspannung gearbeitet wird. Hinzu kommt der Nachteil, daß die notwendige große Wölbung der Folien, insbesondere im Fensterrandbereich, zu höheren Absorptionsraten aufgrund des geneigten Strahleinfalls führt.It is also known to arrange several thin foils one behind the other in the direction of the beam in such a way that individual spaces which are sealed off from the beam generation space and the atmosphere are created. A cooling gas is passed through these rooms in such a way that the pressure difference between the jet-generating room and the atmosphere is divided between the individual rooms by increasing the mean static pressure from room to room. The sum of the Thicknesses of the individual foils correspond to at least the thickness of a foil of a beam exit window with only one foil (DD-PS 102 511; US-A-3 162 749). Since the minimum possible film thickness is limited by the manufacturability of vacuum-tight films, and the absorption of the individual films adds up, the absorption losses are very high here, especially when working with a relatively low acceleration voltage. In addition, there is the disadvantage that the large curvature of the foils, particularly in the window edge area, leads to higher absorption rates due to the inclined beam.

Weitere bekannte Lösungen bestehen darin, daß zur Begrenzung der Zugspannungen in der Folie mechanische Stützkonstruktionen verwendet werden. Die Aussparungen in diesen Stützkonstruktionen sind eng aneinander und z. T. nach der Vakuumseite konisch so verlaufend angeordnet, daß die die Folie stützenden Stege zwischen den Aussparungen vakuumseitig spitz auslaufen (DD-A-207 521, DE-A-18 00 663). Dadurch werden die Elektronen, die auf die Flächen der Stützkonstruktion auftreffen, ohne vollständigen Energieverlust reflektiert und treten danach zumindest teilweise aus dem Fenster aus. Selbst eine derart gestaltete Stützkonstruktion hat jedoch den Mangel, daß die Minderung der effektiven Elektronendurchtrittsfläche und damit der zusätzliche, durch die Stützkonstruktion bedingte Leistungsverlust des Elektronenstrahls 30 % und mehr betragen kann. Hinzu kommt als weiterer Nachteil, daß die thermische Belastung der Stützkonstruktion sehr hoch ist und folglich hohe Anforderungen an die Wärmeleitung und Wärmeabführung gestellt werden. Häufig verwendet man kühlwasserdurchflossene Stützkonstruktionen) die aber größere Stützlamellen erfordern, was sich durch den daraus resultierenden Schattenwurf nachteilig auf die Homogenität des hinter dem Fenster liegenden Bestrahlungsfeldes auswirken kann (DE-A-19 18 358).Other known solutions consist in that mechanical support structures are used to limit the tensile stresses in the film. The recesses in these support structures are close together and z. T. after the vacuum side arranged conically so that the webs supporting the film between the recesses end on the vacuum side (DD-A-207 521, DE-A-18 00 663). As a result, the electrons that strike the surfaces of the support structure are reflected without complete loss of energy and thereafter at least partially exit the window. However, even a support structure designed in this way has the defect that the reduction in the effective electron passage area and thus the additional power loss of the electron beam caused by the support structure can be 30% and more. In addition, there is a further disadvantage that the thermal load on the support structure is very high and consequently high demands are made on the heat conduction and heat dissipation. Frequently, support structures through which cooling water flows are used, but which require larger support lamellae, which can have a disadvantageous effect on the homogeneity of the radiation field behind the window due to the resulting shadow (DE-A-19 18 358).

Es wurde weiterhin versucht, die genannten Mängel von Stützkonstruktionen dadurch zu mindern, daß neben einer besonderen geometrischen Gestaltung die strahlbeaufschlagten Flächen poliert und mit Elementen hoher Ordnungszahlen beschichtet werden (EP-A-0 195 153). Auch diese Maßnahmen können jedoch besagte Mängel nicht grundsätzlich vermeiden. Hinzu kommt, daß eine solche Ausführung der Stützkonstruktion sehr aufwendig ist.Attempts have also been made to alleviate the above-mentioned deficiencies of support structures by polishing the surfaces exposed to the beam and coating them with elements of high atomic numbers in addition to a special geometric design (EP-A-0 195 153). However, these measures cannot fundamentally avoid said deficiencies. In addition, such a design of the support structure is very complex.

Alle genannten Lösungen, die eine Stützkonstruktion enthalten, haben gemeinsam den Nachteil, daß die Abstände zwischen dem Strahlaustrittsfenster und dem Bestrahlungsgut vergrößert werden müssen, um den Einfluß des Lamellenquerschnitts auf die Homogenität des Bestrahlungsfeldes zu verringern. Damit ergeben sich jedoch erhöhte Verluste in der Gasstrecke zwischen Austrittsfenster und Bestrahlungsgut, was sich besonders bei relativ niedrigen Beschleunigungsspannungen nachteilig auf die verfügbare Bestrahlungstiefe und Dosisleistungsdichte auswirkt.All of the solutions mentioned, which contain a support structure, have the disadvantage in common that the distances between the beam exit window and the material to be irradiated must be increased in order to reduce the influence of the lamella cross section on the homogeneity of the radiation field. However, this results in increased losses in the gas path between the exit window and the material to be irradiated, which has a disadvantageous effect on the available radiation depth and dose rate density, in particular at relatively low acceleration voltages.

Der Erfindung liegt die Aufgabe zugrunde, ein Elektronenstrahlaustrittsfenster der eingangs genannten Art zu schaffen, welches ohne eine massive wassergekühlte Stützkonstruktion auskommt, eine geringe Leistungsabsorption aufweist, besonders auch für Elektronenstrahlen relativ geringer Beschleunigungsspannung geeignet und einfach herstellbar ist.The invention has for its object to provide an electron beam exit window of the type mentioned, which does not require a massive water-cooled support structure, has a low power absorption, is particularly suitable for electron beams of relatively low acceleration voltage and is easy to manufacture.

Erfindungsgemäß wird die Aufgabe nach den Merkmalen des Anspruches 1 gelost. Weitere Ausgestaltungen sind in den Unteransprüchen beschrieben.According to the invention the object is achieved according to the features of claim 1. Further configurations are described in the subclaims.

Die Abstützung der Metallfolie durch das aus hochwarmfesten Faserbündeln gebildete Stützgitter sowie die Belastung der Faserbündel auf Zugspannung gestatten eine Querschnittsminimierung der Stützgitterkonstruktion und damit eine wesentliche Reduzierung der Strahlverluste im Strahlaustrittsfenster. Die Verwendung von Kohlenstoffaserbundeln für das Stützgitter ist aufgrund der geringen elastischen Dehnung und des geringen Temperaturausdehnungskoeffizienten besonders vorteilhaft. Die Gewährleistung eines auch unter Belastung etwa kreisförmigen Querschnitts der Faserbündel erfolgt z. B. durch Verdrillen der Filamente. Die Verwendung von Faserbündeln aus einem hochwarmfesten Werkstoff ermöglicht die Aufrechterhaltung eines hohen Temperaturgradienten über dem Stützgitter in Strahlrichtung sowie die Abführung eines wesentlichen Teiles der im Stützgitter absorbierten Strahlleistung durch Wärmestrahlung. Bei Verwendung einer Metallfolie aus Titan und Kohlenstoffaserbündeln als Stützgitter ist es zweckmaßig, die Metallfolie auf der Vakuumseite mit einer Sperrschicht, vorzugsweise aus Titanoxid, zu versehen, um chemische Reaktionen zwischen dem Werkstoff des Stützgitters und der Metallfolie zu vermeiden. Eine ähnliche Sperrschicht kann auch auf der Druckseite der Folie zweckmäßig sein, um die unerwünschte Eindiffusion der gasförmigen Kontaktpartner der Metallfolie zu vermeiden.The support of the metal foil by the support grid formed from high-temperature fiber bundles and the loading of the fiber bundle on tensile stress allow a cross-sectional minimization of the support grid construction and thus a substantial reduction in beam losses in the beam exit window. The use of carbon fiber bundles for the support grid is particularly advantageous because of the low elastic expansion and the low coefficient of thermal expansion. Ensuring an approximately circular cross-section of the fiber bundle under load takes place, for. B. by twisting the filaments. The use of fiber bundles made of a highly heat-resistant material enables the maintenance of a high temperature gradient over the support grid in the beam direction as well the dissipation of a substantial part of the beam power absorbed in the support grid by heat radiation. When using a metal foil made of titanium and carbon fiber bundles as a support grid, it is expedient to provide the metal foil on the vacuum side with a barrier layer, preferably made of titanium oxide, in order to avoid chemical reactions between the material of the support grid and the metal foil. A similar barrier layer can also be expedient on the pressure side of the foil in order to avoid the undesired diffusion of the gaseous contact partners of the metal foil.

Die Faserbündel bilden mit dem Befestigungsrahmen einen Winkel ungleich 90°. Durch eine geeignete Anpassung dieses Winkels an die Fensterbreite, den Abstand der Faserbündel untereinander und die Leistungsdichteverteilung des Elektronenstrahles wird auf dem bewegten Bestrahlungsgut die Bestrahlungshomogenität verbessert. Die Metallfolie kann auch auf der Druckseite in bekannter Weise durch eine Gasströmung, vorzugsweise in Richtung der Faserbündel, gekühlt werden.The fiber bundles form an angle not equal to 90 ° with the fastening frame. Appropriate adaptation of this angle to the window width, the spacing of the fiber bundles from one another and the power density distribution of the electron beam improve the irradiation homogeneity on the moving material to be irradiated. The metal foil can also be cooled on the pressure side in a known manner by a gas flow, preferably in the direction of the fiber bundle.

Das erfindungsgemäße Strahlenaustrittsfenster ist besonders für relativ niederenergetische Elektronenstrahlen und geringe Distanz zwischen Strahlaustrittsfenster und Bestrahlungsgut geeignet.The radiation exit window according to the invention is particularly suitable for relatively low-energy electron beams and a short distance between the beam exit window and the material to be irradiated.

An einem Ausführungsbeispiel wird die Erfindung näher erläutert. In den zugehörigen Zeichnungen zeigen:

  • Fig. 1: eine Draufsicht auf einen Rahmen mit Stützgitter eines Elektronenstrahlaustrittsfensters,
  • Fig. 2: einen Schnitt durch ein Elektronenstrahlfenster,
  • Fig. 3: einen Teilschnitt (stark vergrößert) durch ein Faserbündel mit der Metallfolie.
The invention is explained in more detail using an exemplary embodiment. In the accompanying drawings:
  • 1 : a plan view of a frame with a support grid of an electron beam exit window,
  • 2 : a section through an electron beam window,
  • 3 : a partial section (greatly enlarged) through a fiber bundle with the metal foil.

Das Elektronenstrahlaustrittsfenster gemäß Fig. 1 und 2 besteht aus dem Rahmen 1 mit der Öffnung 2 für den Strahlaustritt, deren Bereich durch ein Stützgitter 3, bestehend aus Faserbündeln 4 aus Kohlenstoff, abgedeckt ist. Die Faserbündel 4 sind in Nuten 5 stoffschlüssig durch Auffüllen von Gießharz 6 verankert. Auf dem Rahmen 1 ist eine auf dem Stützgitter 3 aufliegende Metallfolie 7 aus Titan aufgeklebt. Die Faserbündel 4 des Stützgitters 3 sind zur Verbesserung der Homogenität der Bestrahlung in einem Winkel α < 90° zum Schenkel des Rahmens 1 angeordnet.
Der Rahmen 1 hat auf der Gegenseite des Stützgitters 3 eine Dichtfläche 8, die an dem Elektronenstrahlerzeuger (nicht gezeichnet) vakuumdicht anliegt.
Zur Begrenzung der Zugspannung in den Faserbündeln 4 haben diese einen Durchhang h. Unter Wirkung der anliegenden Druckdifferenz legt sich die Metallfolie 7 an das Stützgitter 3 an. Zur Gewährleistung einer annähernden Kreisform der Faserbündel 4 auch unter der Belastung durch die Metallfolie 7 sind die Faserbündel 4 verdrillt.1 and 2 consists of the frame 1 with the opening 2 for the beam exit, the area of which is covered by a support grid 3 consisting of fiber bundles 4 made of carbon. The fiber bundles 4 are firmly anchored in grooves 5 by filling in casting resin 6. On the Frame 1 is glued to the support grid 3 of metal foil 7 made of titanium. The fiber bundles 4 of the support grid 3 are arranged to improve the homogeneity of the radiation at an angle α < 90 ° to the leg of the frame 1.
The frame 1 has, on the opposite side of the support grid 3, a sealing surface 8 which bears against the electron beam generator (not shown) in a vacuum-tight manner.
To limit the tensile stress in the fiber bundles 4, these have a sag h. Under the effect of the applied pressure difference, the metal foil 7 lies against the support grid 3. To ensure an approximately circular shape of the fiber bundles 4, even under the load from the metal foil 7, the fiber bundles 4 are twisted.

Im Ausschnitt Fig. 3 ist dargestellt, daß die aus dem Elektronenstrahlerzeuger austretenden Elektronenstrahlen 9 sowohl auf die Metallfolie 7 als auch auf die Faserbündel 4 des Stützgitters 3 auftreffen. Während die Elektronenstrahlen 9 die Metallfolie 7 unter Energieverlust durchdringen, wird die auf das Faserbündel 4 auftreffende Strahlleistung nahezu vollständig von diesem absorbiert und in Wärme umgesetzt. Der Bildungsort der Wärme ist, abhängig von der Elektronenenergie, auf die strahlseitige Peripherie 10 des Faserbündels 4 begrenzt. Bedingt durch die schlechte Wärmeleitung über dem Querschnitt des Faserbündels 4 und der auf der Druckseite durch einen Gasstrom gekühlten Metallfolie 5 entsteht über dem Querschnitt ein hoher Temperaturgradient. Dadurch wird ein Großteil der in den Faserbündeln 4 absorbierten Leistung in der Gegenrichtung 11 zu den Elektronenstrahlen 9 abgestrahlt. Die vergleichsweise gute Wärmeleitung der Metallfolie 7 hat zur Folge, daß die an den einzelnen Fasern des Faserbündels 4 anliegende Metallfolie 7 über ihrem Querschnitt eine etwa konstante Temperatur besitzt.3 shows that the electron beams 9 emerging from the electron beam generator strike both the metal foil 7 and the fiber bundles 4 of the support grid 3. While the electron beams 9 penetrate the metal foil 7 with energy loss, the beam power impinging on the fiber bundle 4 is almost completely absorbed by the latter and converted into heat. Depending on the electron energy, the place of formation of the heat is limited to the periphery 10 of the fiber bundle 4 on the beam side. Due to the poor heat conduction over the cross section of the fiber bundle 4 and the metal foil 5 cooled on the pressure side by a gas stream, a high temperature gradient arises over the cross section. As a result, a large part of the power absorbed in the fiber bundles 4 is radiated in the opposite direction 11 to the electron beams 9. The comparatively good heat conduction of the metal foil 7 has the consequence that the metal foil 7 lying against the individual fibers of the fiber bundle 4 has an approximately constant temperature over its cross section.

Auf der Metallfolie 7 ist beidseitig eine Sperrschicht 12 aus Titanoxid aufgebracht, um chemische Reaktionen zwischen dem Stützgittermaterial sowie den gasförmigen Reaktionspartnern und der Metallfolie zu reduzieren.A barrier layer 12 made of titanium oxide is applied to the metal foil 7 on both sides in order to reduce chemical reactions between the support grid material and the gaseous reaction partners and the metal foil.

Claims (16)

  1. An electron beam exit window, consisting of a frame for vacuum-tight attachment to the electron beam generator, a vacuum-tight metal foil which is permeable to the electron beam and a support structure for the metal foil, characterized in that a support grating (3) of fibre bundles (4) is arranged bearing on the vacuum side of the metal foil (7), consisting of a highly heat resistant material, in that the support grating (3) is tensioned in the frame (1) and in that the metal foil (7) is arranged vacuum-tight on the frame (1).
  2. A device according to claim 1, characterized in that the fibre bundles (4) consist of carbon filaments which are twisted.
  3. A device according to claim 1 and/or 2, characterized in that the fibre bundles (4) are bound with carbon.
  4. A device according to claim 1, characterized in that the fibre bundles (4) are attached to the frame (1) with a defined sag by a material bond or by interlocking.
  5. A device according to claim 4, characterized in that the fibre bundles (4) are laid in grooves (5) formed in the frame (1) and which are thereafter sealed preferably with cast resin (6).
  6. A device according to at least one of claims 1 to 5, characterized in that the fibre bundles (4) run parallel to one another or cross in the frame (1).
  7. A device according to claim 6, characterized in that the fibre bundles (4) run at an angle a other than 90° to the edge of the frame (1).
  8. A device according to at least one of claims 1 to 7, characterized in that the frame (1) is made from carbon fibre reinforced carbon (CFC).
  9. A device according to at least one of claims 1 to 7, characterized in that the frame (1) is made from metal.
  10. A device according to at least one of claims 1 to 9, characterized in that the frame (1) is so formed and connected to sealing surfaces or sealing elements that it is simultaneously a sealing component.
  11. A device according to at least one of claims 1 to 10, characterized in that the metal foil (7) is made from titanium or a titanium alloy.
  12. A device according to at least one of claims 1 to 11, characterized in that barrier coatings (12) acting as a diffusion barrier are applied to the surfaces of the metal foil (7).
  13. A device according to claim 12, characterized in that the barrier coating (12) is titanium dioxide in the case of fibre bundles (4) of carbon and a metal foil (7) of titanium.
  14. A device according to at least one of claims 1 to 13, characterized in that the metal foil (7) is bonded vacuum tight on to the frame (1).
  15. A device according to claim 14, characterized in that the bonded region is protected by a covering from entry of back-scattered electrons.
  16. A device according to at least one of claims 1 to 15, characterized in that means for creating a cooling gas flow are arranged in the region of the pressure side of the metal foil (7).
EP93911733A 1992-06-15 1993-05-03 Electron beam exit window Expired - Lifetime EP0646283B1 (en)

Applications Claiming Priority (3)

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DE4219562A DE4219562C1 (en) 1992-06-15 1992-06-15
DE4219562 1992-06-15
PCT/DE1993/000402 WO1993026032A1 (en) 1992-06-15 1993-05-03 Electron beam exit window

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EP0646283A1 EP0646283A1 (en) 1995-04-05
EP0646283B1 true EP0646283B1 (en) 1997-01-22

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US (1) US5561342A (en)
EP (1) EP0646283B1 (en)
JP (1) JPH08501651A (en)
DE (2) DE4219562C1 (en)
WO (1) WO1993026032A1 (en)

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US7768267B2 (en) 2007-07-11 2010-08-03 Brooks Automation, Inc. Ionization gauge with a cold electron source

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US7768267B2 (en) 2007-07-11 2010-08-03 Brooks Automation, Inc. Ionization gauge with a cold electron source

Also Published As

Publication number Publication date
WO1993026032A1 (en) 1993-12-23
JPH08501651A (en) 1996-02-20
US5561342A (en) 1996-10-01
EP0646283A1 (en) 1995-04-05
DE4219562C1 (en) 1993-07-15
DE59305276D1 (en) 1997-03-06

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