DE1764179A1 - X-ray tube - Google Patents

Description

Dr. Herbert Schob ~ PHN.25G6 Patent attorney. Va / ÄvdV

Applicant: _N γ _# p _hilips · Gloeilampenfabriekefl
'"■ ■■ PHI- 2508

Ann- \ τ- _{17 #} April 19-68

"X-ray tube".

• The invention relates to an X-ray tube,

which is provided with an X-ray exit window made of beryllium, so that soft X-rays with a length of not less than 15 A are well transparent. The window is placed in the vend of the tube, which is made of metal. Za let known to drink in such a tube means that prevent the feneter from being hit by electrons. For the purpose of the wake-up use, there is an electrostatic A: ucl. Juf cer ancde of the X-ray tube

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attached 1st. Ξ »is not lukewarm aöglioh - and at least with X-ray tubes xit a metal wall is often undesirable - that window and thus the wall of the tube, which is insulated from the cathode, has the same Has potential like the cathode. Welter is the one to relax Sufficient space for the arrangement of animals exhibiting cathode potential shielding gauze-like electrode required enlargement of the Distance between the electron impact point on the anode and the Window undesirable.

^ Electrons that hit the anode at high speed and then end up at the window due to elastic reflection, in an X-ray tube with a window that is transparent to soft radiation, because the beryllium window is preferably 0.05 for wavelengths above 15% · »Does not have an excess thickness and thus · has such a low heat capacity and thermal conductivity,

there is an overheating due to the energy of the fast electrons is unavoidable, so that such a tube is not possible with anode voltages that are higher than those at which X-rays with the aforementioned vrellenllnee are formed.

The purpose of the invention is to provide the rough part cu

avoid. In an X-ray tube according to the invention, the Bundelkenal in the axial direction of the tube at the point of the beam exit window and surrounded on the inside by a strong magnetic field, whose cross lines are essentially parallel to the Röhrenachs · he » • trek, while the area of almost constant field strength is at least « on the part of the pipe cross-section where the window is located, a H8ch «tbrelte exhibits. In a known X-ray tube with a · « This magnetic field is used to promote the electron bundles

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and the compression of the electron beam »to a minimum cross section is used. Di · conventional electrostatic focusing, the eeignete ₆ by a design of the TrSgers the hot cathode is obtained is sometimes insufficient, and especially not satisfactory, if the electrons are accelerated through a verhSltnisraä'ssig SIZES distance in the direction of the anode. In such FSIs, a magnetic focussing field is used, which preferably has a small focal band. As is well known, this purpose is achieved, among other things, by the fact that the electron impact points are snapped off in the immediate vicinity, in part that a lateral passage for the X-rays is opened between the opposing poles.

Such a lens' power at a maximum ir.amatic induction along the Linaenachee considerably to the Focus at. The magnetic field strength required for this is only obtained under the influence of the saturation of the iron of the pole barn.

On lie in the electron impact point on the.

Ar.cde released, elastically reflecting electrons such a magnetic focusing field acts like a stray field, because the point, ftr. which the electrons are generated, within the effective range and in the range of the high. the Linsenfeidee left. The trajectories of these high initial speeds are then not or almost not influenced by the magnetic field in the vicinity of the point of impact. You therefore understand that there is a The field surrounding the electron orbits is favorable if the electrons reflected from the anode are influenced by the aforementioned llagnetfeld

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at other points they hit the tube window or even to the To return anode.

The invention is explained below by means of a description of an exemplary embodiment with reference to the drawing. Show ss »

Fi ^. 1 ia section through the X-ray tube according to the invention

Figures?, 3 and 4 some cross-sections through the Anode part of the tube at the height of the window *.

A glass jacket 1 surrounds a vacuum-pumped space in which the hot cathode? is arranged ', the support 3 is Festgtschmelzen on the glass wall. Opposite the cathode 2 ends a metal tube 4 which protrudes over a melt 5 <* n of ^ and4i · '. The metal tube 4 consists of tinea ferromagnetic material, for example iron, and has a copper anode 6, kit at the end, which seals the tube 4 in a vacuum-tight manner. The usual liaasnahaien for cooling the anode are not shown in the drawing.

In the wall of the metal pipe «4 there is a passage opening 7 for the X-rays, the sittelc of a thin-walled one Beryllium window »θ closed, which has a thickness of e.g. about 0.05 na bat.

Due to the mechanical and electrical connection between the window 6 and the anode tube 4, the window daa Potential like the anode 6. If now the Kntcode 2 and the anode connected to the operating voltage are elastic from the anoea surface 9 reflected electrons in the direction of daa Window 9 deflected, aas ale point of impact for such electrons

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which are accelerated by the applied vehicle voltage and their Speed is hardly reduced as a result of the distraction, one exposed to intense heat. The electrons are through a Magnetic field derived from the window, the magnetic field length de · durcl the bundle channel formed by the inner wall of the anode tubes · 4 in height de · Pensters the *> electron paths ending at the electrode are ring-shaped umecblleset. Such an "umsohlie the Slek'tronenbahnen" "ends · etarkea magnetic field can sighting the invading and sioh sun Electrons moving towards the window are changed enough so that such electrons go past a window door and to other places hit in the anode tube or sur. The anode can be returned. the The usual shielding of the window "becomes by means of a magnetic field" ronSee more than 5000 Qa'u ·· received.

_φ For the sinus control α ·· stray flux ···· iat «ine low«

Magnetic induction is required, so that a thick-walled anode tube 4 must be used, since at the height of the window there is a annular · has interruption. If the Xrreguhg is not too strong as a result of the interruption of the poles, the drilling becomes the glaioh ··· blesses »ch shielded and thus becomes there« field in this Space suppressed. - A magnet is used for Irteugen de · Felde «! Aohea yoke 10 ', there I anode tube 4 aneohlieaat and with a Brregermagnetapule 11 veraver ist * The required FtId can also result in a Permanent magnets. The sur BilftUBf the ICagnetpole provided interruption 12 in the anode tube 4 duroh elm not magnetic · bridged material.

Around oas field mBgliohst dense sn d ·· Window 8 see below bring the wall thickness of the anode tube on the side

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of the window enlarged. The cross-sections of FIGS. 2 and 3 are designed in such a way that the weight of the anode tube can be lower while maintaining a very strong felue at the window. The cross-section of the shape shown in FIG. 4 is preferable if one or more windows 8 permeable to X-rays exiting in different directions are installed, which sometimes do so

for X-ray diffraction devices with several outlet openings for the x-rays is the case.

Ss emphasizes eic :, that the dimensions of the

Tubes almost identical to those of the structure without the required window partition can be.

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Claims (4)

-7- ~ PHN.2508 PATgSTASSPRUECHSi 1. X-ray tube, which is made of 3eryllium with an un-; for soft X-rays well permeable to X-rays, which is mounted in a metal Yar. part with a ring-shaped cross-section of the tube, which forms a whole with the anode, characterized in that the bundle channel in the axial direction of the tube βία radiation exit window (7 _t ß) and on the inside of this window "is uasschloseen by a strong liatTietfeid whose lines of force extend calibrated substantially parallel .to the tube axis, ws'hrend dss area with a substantially constant field strength at least on the side dee lohr cross section, located wc de" window is , has a maximum width. 2. X-ray tube according to claim 1, characterized in that the StSrke the metal edge (4) locally durcL with rinj.förmifecc cross section oblateness of the inner cross-sections is vergr6Bsert, and that there · Strahlenaustrittsfeneter (7 _t 8) in this part d * iet attached r Fland . 3. X-ray tube according to ^A nspruch 1, terized in lines, ^ DAEs the inner and Aueeenqutrechnitt the üetallviand are circular and are arranged eccentrically in relation to each other, wherein dae Strahlenaustrittefeneter in the thick peripheral portion mounted ibt. 4. X-ray tube according to claim 1, characterized in that that the Lletallr.and a square inner cross-section and has a circular Ausse.nquersohnitt. 109822 / 05U ^BAD I e r s e i t