DE2124167A1 - Evacuated electron discharge tube - Google Patents

Description

DCMDLLER-BORe DiPL-PHYS. DR. MAN ITZ D I PL-CH EM. DR. D EUFEL DIPL-ING. FINSTERWALD DIPL-ING. GRÄMKOW 2124167 PATENT LAWYERS

Munich, the (4, MAf «|

Hl / B - E 1039

ENGLISH ELECTRIC VALTE COMPANY LIMITED Bush House, Aldwych, London, W.C. 2.

England

Evacuated electron discharge tube

The invention relates to an evacuated electron discharge tube and relates in particular to such a discharge tube, which has a casing or a bulb has, in which a high vacuum are maintained for satisfactory operation got to. It is particularly advantageous in a high power microwave electron discharge tube.

General practice with evacuated electron discharge tubes is to have a chemically active getter in the To attach a piston that is pumped out to the desired high vacuum and sealed. The lifespan and Performance or the efficiency of the tube

1 098 4 87 U2 9

Dr. MOHw-Bort Or. Manitz · Dr. German Dipl.-Ing. RniNrwaW Dipl.-Ing. Grimkov Iraumdnraig, Am BOrQwparfc β 8 MOndMn 22, Rob «1-Koth-Slra6 · 1 7 Stuttgart - lad Coniutolt T «Mo« (0531) 73887 T.l.fon (0811) 2? 3645, T.l.x S220M iribpet MarkWrofl · 3, TtWbn (0711) «72 * 1 Bank ι Z.ntrolka.ii Baytr. Volksbank.n, MOnch.n, account no. 9822 PotttdiMfc: MOndMn f! 4ti

depend on the maintenance of the vacuum and the Vacuum tightness of the sealed piston in connection with the ability of the chemical getter with the gases that are created in the tube during its use and storage, the vacuum to maintain. Chemical getters are appropriate in many cases, but they are only able to to deal with gases that react with the getter material, but not with CIL and noble gases in general. As a result, in certain cases they are not really adequate and the practice is a getter ion pump The more expensive electron discharge tubes have been added to better upright to maintain the vacuum and thus extend the satisfactory life of the tube. A known getter ion pump, however, has the significant practical disadvantage that a external source of electrical power for their operation is required. In addition, the getter ion pump only causes pumping when the external power source is switched on - but not when the Tube is only stored.

The aim of the invention is to avoid this disadvantage.

According to the invention, an evacuated electron discharge tube device with an electron discharge tube an ion getter pump device which comprises a body made of radioactive material, which is arranged to act as a source of power therefor; the facility is located either in a vacuum-tight housing formed by the piston of the tube, or in a vacuum-tight one Housing that holds the tubular piston, a casing or

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a piston for the device and a connecting passage between them.

The body of radioactive material can be a source of alpha particles. Preferred examples of such materials are CbUzj-2 ^and - ^ 24V ^Venn either of these

Materials used are preferably associated with facilities that have an undesirable accompanying Reduce x-rays from it. Such devices can, for example, be made of a thin mild steel sheet be educated.

Instead of a source of alpha particles, a Source of beta particles for the body of the radioactive Materials are used. A preferred source of beta particles is tritium - preferably in Ti dissolved tritium.

Preferably, the pump device is constructed so that it has the effect of an ion getter pump with the of a chemical getter.

In an embodiment according to the invention, the device comprises an enclosure with a support base or a support base and a hollow cathode and become a body of radioactive material, a collector, and an anode carried by the pedestal in the interior of the cathode, the envelope or encapsulation is such that a free path is provided for grass from the inside to the outside, and the overall arrangement is such that emitted particles are confined within the enclosure are.

109848/1420

At least the inner surface of the cathode is preferably made of chemical getter material, as is also preferably the collector and the anode. The coloring of emitted particles in the encapsulation can be achieved by providing the cathode- "; ir_l the base made of / for particles impermeable! ^" Materials, whereby sis are designed as constructions open at one end and m. ± t their open structures Eaden each other over-lappeai be arranged one in the other. For example, the cathode ■ and the base may be located in the Fori £ ei ar hol "- ?. s' ε sylindrisohen Construction: αε, Fuei ~ SeilcLe.n impermeable Msite-ri &l" is only einsa Ends Df.?sz provided will.,. the two constructions. have different diameters imi coaxial sit their open. hands IToöi'lappend. "ui *> I one in & © 3? others arranged sLdA, around a ring-fringed SwiiScLsEraxoa Sifirrfes. you lassii them, wc they iisb. overlap.

In the case of an iaisfiiliniiig form of the facility, indicate. the cathode and the S ^ eIiGl ^ e ^ ceils ¹ dis SOr-a ■ sir.fc.s only eh one end open hollow, cylinder? on, with the swei cylinder mt- different Tv.vckr ^ .sse-'m

provided and coaxial with their open ends in the other are attached, -as sinssi ιingfönaigen Leave space between them frsisiil, and the The base of the cathode cylinder and one in the nozzle Source for alpha particles and a collector in the Area of source bears; an anode rod or wire is provided which closes close to zn ^ 031 End of the cathode cylinder extends and which is carried by the collector 5 a high

109848 / U29

Resistance is between the collector and the alpha particle source switched and a connection between the source and the cathode cylinder is provided.

In another embodiment of the device are the cathode and the base each in the form of a hollow cylinder open only at one end provided, the two cylinders having different diameters and being coaxial with their open ones Ends one in the other to leave an annular space between them, and the base carries the cathode cylinder and in it a source of beta particles and a collector adjacent to the source; an anode rod or wire is provided, which extends near the closed end of the cathode and which is carried by the source; a high one Resistance is connected between the collector and the beta particle source and there is a connection provided between the collector and the cathode cylinder.

In both of the above-mentioned embodiments, the preferred material for at least the interior is the Cathode and also for the collector and the anode Ti and a preferred material for the The base is glass. A shield, for example made of Mo, is also preferred in both embodiments provided to prevent metal from splashing on the base.

Another embodiment of the pumping device comprises an outer carrier with a thin layer of radioactive material on its inner surface,

1 O 9 fU 8 / U 2'8

a coaxial anode, at least one coaxial grid between the anode and the support, and a pair of Shields, one of which is provided at each end of the anode and the coaxial support structure. at In one embodiment of this type the layer is an alpha particle source and there are two coaxial gratings provided with the interior connected to the source and shields and being relatively permeable Ion collection grid is provided and the exterior is connected to the anode and as a relatively impermeable one Alpha particle collection grid is provided. At a In another embodiment, the layer is a beta particle source and only one grid is provided, which is with connected to the shields, operated with a negative potential and acted as a beta particle is provided. In these two embodiments, the electrons run in orbits around the central anode, to cause ionization.

The invention is described below with reference to the drawing, for example; in this shows:

1 and 2 show an elevation or cross section of an embodiment and % form of a pumping device according to the invention, and FIG. 3 / a

View similar to FIGS. 1 or 2 of another embodiment.

The pump shown in the drawing is suitable as well as what can be used as a radio-control pump, i.e. a getter pump that operates on a radioactive isotope as well as a chemical getter to act. According to the drawing is a glass slide base 1 and a cathode 2 in the form of a cylindrical, provided at one end of the sleeve. A layer of radioactive isotope material 3 on a Carrier support plate 4 and a Partxkelempfänger 5, from which extends an anode wire or rod 6 from the base and socket in the interior

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7-1124167

worn by the cathode. The base 1 is also provided as a cylinder open at one end. It extends coaxially with the cathode, has a larger diameter than the cathode and its open end overlaps the open end of the cathode, is arranged at a distance therefrom and surrounds it. Support pins 7 melted through the base 1 carry the cathode 2 and similarly melted support pins 8 and 9 carry the support plate 4 and the particle or particle receiver 5 with its anode rod 6 , is provided to prevent metal from splashing on the base ^Λ. A high resistance 11 found in Pig. 2 is not shown, connects the parts 4 and 5 by the pins 8 and 9 and a connection 12, which is also not shown in FIG practical value can be given, for example, the

11
The value of the resistor 11 should be 10 ohms. At least the inner surface of the cylinder 2 can be made of a material such as Ti, Ta or Zr, which forms a satisfactory getter when it is in the form of a freshly as-atomized layer. The cylinder 2 can consist entirely of such a material or of any suitable material with an atomized or sprayed layer of such a getter material on its inner surface. In the present case, Ti is preferred. The particle receiver 5 and the anode rod 6 both also consist of getter material, possibly both of Ti.

The isotope support plate 4 can be made of any suitable material, for example Al and the shield IC, for example consist of Mo

The isotope layer 3 is preferably exposed to an alpha particle emitting radioactive material. It is also preferably a radioactive material that is a has very low gamma radiation emission. There are three known isotopes that meet these requirements,

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namely Po, Gm ^ n ο ^ ¹¹ ^ ^ mpA-i ' ^where ^ - ^ ^{13 the} former has a G-anma radiation emission of only about 0.001%. However, this material has the disadvantage that it volatilizes easily, so the other two materials are preferred. They both emit low-energy X-rays, but it is possible to significantly reduce the X-ray counter display or the X-ray fraction by using an X-ray protective material (not shown). The experiment shows that when using 1 mm thick sheet steel it is possible to reduce the X-ray component to about 0.1% of the alpha emission rate.

Considerations relating to the protection 'fen humans against physiologically damaging radiation put a practical Grense for the dimension of the alpha particle source 3 that can be used must be provided as _s that people for long periods within the radiation range of the present invention Entlaä'üagsrölarenapparat -for are located. Safety regulations currently prohibit continuous irradiation you more than 300m ο wheel / Wöche. This is equivalent to 2m. Bike / hour for one continuously in the Bereiejö. a vacuum tube with a radio-getter-pump in the inside of the seated people »This corresponds to 10 ^ decays per second for 30EeV-G-amma rays. If 0.1% G-sasaia rays are emitted, the maximum 39 meas. Jng of an Alplia-Qaelle would be 10 decays per second . _: _, i ^ ^A oh 2 .Curie amount «

Let 51 ^ 32? Siariehtung above in connection with the 2eiotev, _-::: construction and arrangement are described g dia alpha particles on the inside of the device

109848/1429

limited, since the glass base 1 and the cathode sleeve 2, "die.sich overlap as shown, from one material impervious to alpha particles exist and suffice to achieve this. However, if a other construction, which does not achieve this by itself, is taken - if, for example, a an existing base material permeable to alpha particles is used - can be any known Appropriate outer shielding, not shown, can be used to prevent alpha particles from escaping from the Prevent inside the pump.

As an alpha particle has 2 positive electrical charges carries, an alpha particle source forms a "source" of substantially constant current and if one such source (layer 3 in the illustrated embodiment iPrm) from a collector (collector 5) is separated by a sufficiently high resistance (the resistor 10), a high voltage can be built up. When the pump is in operation, this voltage is used as a drive voltage or control voltage to generate a Provide pumping action in the manner of an electrostatic ion pump.

The device shown is capable of pumping in three different ways, namely by chemical pumping, pumping by ionization by alpha particles, and electrostatic pumping such as by to supply an electrostatic ion pump. If a radioactive source that decays about 10 'per second results, a resistor 11 of 10 'ohms and a build-up voltage of 10 YoIt are assumed, the Receiver 5 bombarded with 10 particles per second, and when 1% of this atomizes new atoms available for chemical reaction with gas molecules, lenn the removal of

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q r -10

10 · ⁷ moles per second are expected, which is 10 To_3? R.1 / sec is equivalent; for pumping through. Ionization through

Alpha particles can also be expected to be

-10

approaching 10 torr. 1 / sec; and the electrostatic pumping by further ionization by electrons provided by the ionization effect of the alpha ropes can be expected to be wider

-10
10 Torr .1 / sec approaches; What one whole awaited

-10-10 approximate pumping speed; from 10 +10 + 10 Torr. 1 / sec. results. When the delivery of ions becomes greater than the current generated by the Alplia Eeilelien, no ion pump ^, occurs »

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9848 / U29

when a beta particle source is used instead of an alpha particle source. Because of the reduced atomization obtained with a beta particle source, a device using such a source (other things being the same) would have a slower pumping speed than a source using an alpha particle source. On the other hand, some beta particle sources do not emit gamma rays and by selecting such a source, gamma ray emission could be avoided. FIGS. 3 and 4 show views similar to those in FIGS. 1 and 2, respectively, of another embodiment of a Baep device for an apparatus according to the invention. This modified embodiment has the advantage of providing a large area radioactive source. Both alpha and beta sources operate with high efficiency when in thin film form and, as a result, large area sources are in many cases desirable.

According to Figures 3 and 4, there is an alpha particle source by a thin film 33 of a suitable radioactive material on the inner surface of an open ended cylindrical support support member 44 coaxially surrounding an anode rod 66 is provided. A glass base disk or glass base plate 101 CiQ Fig. 3 not shown) directly or indirectly carries parts 33, 44 and 66 and also the two end shields 110 (not shown in Figure 3) as well as two coaxial cylindrical ones Grids 13 and 14- with different diameters between the parts 66 and 33-44. The outer grid 14- can be quite impermeable and designed so

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that it is believed to be about? O% of the alpha particles collects.

The inner grid 13 is intended to collect ions and can be relatively transparent. The outer grid 14 and anode 66 are connected together and operated at an appropriate positive potential. The inner grid 13, the source 33 with its support 44 and the shields 110 are connected to one another. This pumping means operates in the manner of a so-called "Orbitrons" that electrons infinitely central in the r direction about the.

Anode 66 may run or crimp and thus cause ionization. A high resistance 11 connects the anode with the inner grid.

In Figures 3 and 4, a pump device is with an alpha particle source. In the event that a beta component source is required, can a construction, not shown, generally similar to that used in Figures 3 and 4, which however, differs from that of FIGS. 3 and 4 in the manner distinguishes that only a single grid between the. central anode and the radioactive material (now a beta particle source) is present on the inside of the cylindrical support. This grid is thick, designed so that it collects most of the beta particles, is at a negative potential held and is connected to the end shields or end shields. The anode rod and the beta particle source ■. -Rjrden operated at a positive potential. As the electrons run or circle during operation around di® central anode.

- patent claims -

1098A8 / U29

Claims (1)

Claims Evacuated electron discharge tube device with an electron discharge tube therethrough characterized in that an ion getter pump device with a body of radioactive material (3) is provided, which is so arranged is that he acted as a source of power for this acts, and that the device is located within a vacuum-tight housing ", which is formed by the piston of the tube. 2. Evacuated Electron Discharge Tube Equipment with an electron discharge tube, dadurcii marked that a '. · ox-engetter ·' Pamping device with a body of radioactive material Material is provided which is arranged in such a way that it acts as a source of performance therefor, and that the device is in a vacuum-tight manner Housing is located that the tubular piston, a piston for the device and a connecting channel includes between these. 3. Device according to claim 1 or 2, characterized in that the body consists of radioactive material is an alpha particle source. 4. Device according to claim 3, characterized in that the particle source C >. Device according to claim 3> characterized in that the particle source is Am ₂ ^. - 13 -
98 4 8 · / U-2-Su 6. Set up after. Claim 4 or 5, characterized in that the particle source Devices are assigned that reduce an undesirable accompanying X-ray radiation from this. 7.. Device according to claim 6, characterized in that the devices for reducing the X-rays are formed by fluent iron sheet or soft steel sheet. 8. Device according to claim. 1 or 2, thereby g e - indicates that the body made of radioactive material is iron · Beta-i ^ä eilciieaGiielle » 9 · establishment n & oii .änEv ^ uah 8 .. daä-iireli geke η .η ~ p-eiehnet. The partial class of tritium or acid dissolved in Ti _{is E} dfy ± i22icii gsksiiiiEeicliüSu ^ -IaS the . PajspeAi2Eic3! AÄimg so tvi-äuniiert is, o, a £ 'they d ^ 2 eaemlscnea G-etters combination 11. Device according to one of the previous claims, characterized in that the device has an encapsulation which comprises a support base and a hollow cathode, that a body of γοη radioactive material, a collector and an anode from the pedestal in the interior the cathode and that the encapsulation is such that a free meg for gas from the interior au whose exterior is provided, and the entire The arrangement is such that the emitted particles are confined or trapped in the enclosure. 12. The device according to claim 11, characterized in that the inner surface of the Cathode consists of a chemical getter material. 13 «Device according to claim 12, characterized in that the inner surfaces of the The collector and the anode also consist of a chemical getter material. 14 ·. Device according to one of claims 11 to 13? characterized in that confining the emitted particles in the enclosure is achieved in that the cathode and the base of materials impermeable to particles are provided, these are designed as structures, each of which is open at one end, and they old their open ends are arranged overlapping each other one in the other. 1i ?. Device according to Claim 14, characterized in that the cathode and the base each in the form of a hollow cylinder structure made of material impermeable to particles airri, dte rur is open at one end, and that the two structures have different diameters and with their open ends overlapping each other and one 'in the other coaxially mounted and one Leave bing space between them where they overlap. 16. The apparatus according to claim 15 _T, characterized in that the cathode and the base 1098A8 / U29 each in the form of a hollow cylinder open only at one end are provided that the two cylinders have different diameters and are mounted coaxially with their open ends one in the other and an annulus between them are free so that the base and the cathode cylinder in the same a source for alpha particles and a collector in the area of the source that carries an anode rod or - wire is provided that is close to the closed end of the cathode cylinder extends and is supported by the collector that a high Resistance between the collector and the alpha particle source is switched and that a connection between "the source and the cathode cylinder is provided is. 17. Device according to claim 15 _s, characterized in that the cathode and the base ^ are each provided in the form of a hollow cylinder open only at one end, that the two cylinders have different diameters and are mounted coaxially with their open ends one in the other and leaving a space therebetween that the base carries the cathode cylinder and therein a source of beta particles and a collector in the region of the source that an anode rod or wire is provided which extends near the closed end of the cathode and carried by the source, that a high resistance is connected between the collector and the beta particle source, and that a connection is provided between the collector and the cathode cylinder. - 16 - 109848 / U29 18 * Device according to claim 16 or 17, characterized characterized in that the material for at least the interior of the cathode and also for the collector and the anode is Ti. 19. Device according to one of claims 16 to 18, characterized in that the material for the base is glass. 20. Device according to one of claims 16 to 19, characterized in that a shield is provided that prevents metal from splashing on the base. 21. Device according to one of claims 1 to 10, " characterized in that the Pump means an outer carrier with a thin layer of radioactive material on it inner surface, a coaxial anode, at least one coaxial grid 'between the anode and the Supports and a pair of shields, "one at each end of the anode and the coaxial support structure". 22. Device according to one of claims 1 to 5 and 21, characterized. that the layer is an alpha particle source? , «$ * ■ that. two coaxial grids are provided that the inner grid is connected to the source and the shields and. as a relatively permeable iononsamel grid is provided and that the outer grid is connected to the anode and as a relatively? ixacluiicöläasi ^ e Alpha-Part 1 chonsaiaaelgitter provided isii _c . after voting the ABe ^ rticfco 1 17th 10984 & / 1429 Hi and 21, characterized in that the layer is a beta particle source and that only one grid is provided, that of the shields is connected, operated at a negative potential, and as a beta particle lattice is provided. -: ·: ■ - iZL'i / 'ι, 2