DE2028921B2 - Ray passage window with soldered-in beryllium disc for high-energy rays - Google Patents

Description

The invention relates to a beam passage window for high-energy beams into which a pane is made Beryllium is soldered in. The beryllium window is usually in the wall of the vacuum-tight bulb Radiation generation or acceleration tube introduced because the beryllium because of its low Atomic number high-energy rays, such as X-rays, gamma rays or corpuscular rays lets through better than the materials that are used to manufacture the remaining parts of the piston. However, the connection between the piston and the window pane must be vacuum-tight and mechanical be durable.

The manufacture of vacuum-tight soldering of the beryllium discs in the piston of X-ray tubes used as windows are usually done with a solder, which contains silver, for example with an alloy of palladium, silver and copper or an alloy that contains an excess of Silver contains copper. On the other hand, the beryllium disc was also electroplated with copper or nickel coated to maintain a good bond when soldering. But it has been shown that apparently due to Diffusion processes or alloying processes through the solder create brittle zones that lead to the formation of cause fine, so-called hairline cracks or greatly reduce the mechanical strength. But this becomes the Manufacturing disrupted, and the windows have to be sealed by special measures and post-processing to come to permanently leak-proof tubes. This is the case to a greater extent when the Beryllium disks are particularly special because of their use in the exit window of an X-ray tube should be thin and radiolucent.

According to the invention is a ray passage window made of beryllium, which in the solution of the problem is soldered tight in a simple manner with good radiation permeability, characterized in that the Beryllium disc is coated with silver at the soldering points. The beryllium disc is made through the layer of silver is protected against the harmful effects of solder by keeping this from forming brittle zones that lead to hairline cracks etc.

being able to lead. The effect of the preferably vapor-deposited silver applied according to the invention can be described in such a way that on the one hand the solder is well wetted on the silver surface and nevertheless only slight harmless alloy formation with the beryllium of the window can be accepted. This is easy to see, especially with gentle occupancy by steaming.
In a simple manner, the invention

ίο soldering z. B. obtained in that the disc from Beryllium is cleaned with a conventional etching solution. This can be about a five percent solution of Be hydrogen fluoride in alcohol. Also a mixture of 40 to 50% nitric acid, 1 to 2% hydrofluoric acid or sulfuric acid and 48 to 59% water can do adequate cleaning. Then will the disk is placed in a vacuum containing 0.1 to 0.2 Torr argon as the residual gas. In this Atmosphere is between the disc on one

μ additional electrode made of aluminum and the grounded Surrounding a glow discharge ignited, which is maintained for 5 to 10 minutes to avoid any To remove impurities (»dusting«). After switching off the current, the soldering points are also Vaporized silver until they are 0.05 to 0.5 μm thick. For soldering, an arrangement in a vacuum can be brought to the working temperature of the solder used for a short time are heated, which is known to be a few degrees above its melting range, with a silver-copper-indium solder z. B. to 720 ° C. The arrangement consists of the frame of the window in which a layer is made Solder, the beryllium window, another layer of solder and finally a retaining ring are inserted. as Lot is z. B. the aforementioned vacuum brazing alloy made of 75% by weight silver, 15% by weight copper and 10% by weight Indium used when the frame of the window is made of monel metal or nickel.

Further features and advantages of the invention are shown below with reference to those shown in the figures Embodiments explained. In the

F i g. 1 shows the plan view of an X-ray tube broken open at the window and in FIG

F i g. 2 shows the exploded view of an arrangement for producing the soldering in a window frame.

«In Fig. 1 with 1 the vacuum flask is the X-ray tube, on the end faces of which the cathode 2 drawn in dashed lines and the cathode 2 as well dashed lines anode 3 are arranged opposite one another. The 0.1 mm thick beryllium disc 4 is inserted tightly in the frame 5, which is also soldered tightly to the outside of the piston 1 is. The beryllium disc, which is 0.1 mm thick, is in the recess of the frame 5 made of Monel metal used that it rests on the shoulder 6 and is held there with a layer of solder. Outwardly the ring 7, which is also made of Monel metal and is soldered on, lies on the beryllium disc 4.

During production (FIG. 2), a ring 8 made of soldering material is first placed on the shoulder 6, on top of it comes the disc 4 made of beryllium and then again follows a ring 9 made of solder, on the last the retaining ring 7 is attached. The rings 8 and 9 are 0.1 mm thick and are made of silver, copper, indium. The disk 4 made of beryllium is at its edge

^b5 vapor-coated with silver at the top and bottom across the width of the soldering rings 8, 9 or the end ring. This is shown on the top and bottom of the plate 4 by the enlarged relative to the other dimensions

10 and 11 indicated. To complete the rd this arrangement, which is 0.3 μm thick, in ι inserted and heated to 720 "C. After the: the frame 5 can be removed id be soldered together with its insert into which he x-ray tube.

1 sheet of drawings

Claims (3)

Patent claims: 1. Beam passage window for high-energy rays, in which a disk made of beryllium with an alloy containing silver is soldered in, characterized in that the disc (4) made of beryllium is coated with silver at the soldering points. 2. Window according to claim 1, characterized in that the pane (4) in the window frame (5) is soldered in by means of an indium-containing solder (8, 9}, after it has been soldered in the usual way cleaned, exposed to a glow discharge and at the soldering points with layers (10. 11) made of silver is steamed. 3. Window according to claim 1, characterized in that when using a window frame (5) made of Monel metal, the disc (4) is gliminted at 0.1 to 0.2 Torr in argon, the layers (10, 11) made of silver 0.05 to 0.5 μm thick and the solder (8.9) from a Mixture of 75 wt .-% silver, 15 wt .-% copper and 10 wt .-% indium.