DE2037029A1 - Ion source - Google Patents

Description

ν.B / JE July 3, 1970

Institute for Plasmaphysics GmbH 8O46 Garching

Ion source

The present invention relates to an ion source, in particular for one based on the principle of a mass spectrometer working device for isotope separation.

Devices for isotope separation based on the principle a mass spectrometer work, stand out in comparison to isotope separators, which work according to different principles work through a very high separation factor. So far, however, it has not been possible to achieve a satisfactory result with such facilities To achieve mass throughput, since ion sources with the required power were not available. the known ion sources, e.g. ion sources in which a vaporized or gaseous material ionized by an electrical discharge or by electron bombardment namely only deliver relatively small ion currents.

The present invention is accordingly based on the object of specifying a high-power ion source, which can be used wherever high ion currents are required, especially in devices for isotope separation, which work on the principle of a mass spectrometer?

The invention is based on an ion source with a Ionization device, which can be fed to the ionizing atoms, and a negatively biasable perforated electrode through which the generated ions can be transported to a consumer

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According to the invention, the above object is achieved solved in such an ion source that the Ionisierungseinrichtimg a heatable, large-area electrode from one Material which is able to ionize the atoms to be ionized by contact ionization, and that a device is provided that between the two electrodes an axial (i.e. running in the direction from one electrode to the other) magnetic constant field generated »

Such a large-area electrode onto which, for example, an atomic beam generated by evaporation of the to be ionized Material can be directed, in combination with the axial magnetic field represents a very productive ion source, with which high ion currents and mass throughputs can be achieved.

Further developments and embodiments of the invention are characterized in the subclaims ₀

The invention is described in the following by embodiments explained in more detail in connection with the drawing, it demonstrate:

Figure "1 is a schematiseh © representation of an ion source according to a first Ausführangsbeispiel dei ³ invention, and

Fig »2 a schematissh © © ines representation · ion source according to a second lusfüiteungslbeigpiel of Erfindong * _e

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10 can be accelerated. A vaporizer device 16 is arranged in front of the ionization electrode 10, e.g. Arrangement 18 is heatable and a beam 20 of atoms of the material to be ionized 22 against the front surface of the Electrode 10 aligns.

In the distance in front of the ionization electrode 10 is a perforated, e.g., reticulated electrode 24 is arranged. Further a device (not shown), for example a cylindrical magnetic coil surrounding the vacuum vessel, is provided which is implemented in the Space between the electrodes 10 and 24, an essentially homogeneous constant magnetic field indicated by an arrow B produced from e.g. 2 to 8 kö.

The ionization electrode 10 consists of a material that ionizes the atoms to be ionized by contact ionization able. This means that the ionization voltage of the atoms to be ionized is comparable to the exit voltage the electrode material must be. For the ionization of alkali and alkaline earth metals as well as uranium and the like, for example, a Electrode made of tungsten, rhenium or tantalum can be used. When using carbon for the ionization electrode elements with even higher ionization potentials can also be ionized.

During operation, the ionization electrode 10 is heated to operating temperature, for example 2500 ^° K, by electron bombardment, and the vaporizer device 16, 18 is put into operation, so that an atom beam 20 directed onto the front surface of the electrode 10 emerges from it. The atoms striking the electrode 10 are ionized by contact ionization and, together with the electrons thermally emitted by the electrode 10, form a plasma held together by the axial magnetic field β, from which the ions emerge through the perforated electrode 24, which is negatively biased with respect to the ionization electrode 10. The negative voltage at the broken electrode 24 only needs to be relatively small (for example 10-20 V) because it

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only serves to hold back the electrons of the plasma. The ions indicated by arrows 28 can then be supplied to your determination, for example they can be placed in an the principle of a mass spectrometer working device for isotope separation occur, which in Fig. 1 only schematically is indicated as a dashed rectangle

The embodiment shown in FIG. 2 operates on the same principle as the embodiment according to Fig. 1 "The device for feeding the but is to be ionized atoms in the apparatus of FIG. £, disposed behind the electrode 10 ^f having perforations 30th The material to be ionized is evaporated, for example, by an annular evaporation ^{boat 16 f} and then passes through the openings 30 * , e§ being ionized through contact with the wall of these openings. The electrode 10 ^f can, for example, be heatable by direct passage of current and, for this purpose, can be provided with a center electrode 32 and a peripheral electrode 34. As in the example according to FIG. 1, the ions generated emerge through the perforated electrode 24. The device for generating the axial magnetic field B is indicated schematically as a solenoid 35 *

The diameter of the electrode 10 is

preferably at least 50 mm. The distance between the electrodes 10 and 24 is preferably about 100 mm or larger.

The electrode 10 * and the vaporizer device can also consist of a heatable hollow body in which the material to be ionized and vaporized is located and which has openings corresponding to the openings 30, from which the vaporized material emerges with simultaneous ionization on the walls.

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Claims (4)

2037023 Claims (l. ion source rait an ionization device, the atoms to be ionized can be fed, and a negatively biasable, perforated electrode through which the generated Ions pass through to a consumer, thereby characterized in that the ionization device has a heatable, large-area electrode (10, 10 *) made of a material which is able to ionize the atoms to be ionized by contact ionization, and that a device is provided which generates an axial magnetic field between the electrodes (10,10 *; 24). 2. Ion source according to claim 1, characterized in that that the ion source includes a vaporizer device (16, 18) which emits a beam (20) from the Atoms to be ionized, which is applied to one of the suction electrodes (24) facing side of the heatable electrode (10) directed igt (Fig. 1). ■ J5. Ion source according to claim 1, characterized in that the heatable electrode (10 *) has openings (^ O) and that on the side of the electrode (10 *) facing away from the suction electrode (24) an evaporator device (16 * I) for the atoms to be ionized is arranged, which pass through the openings (JO) of the electrode (10 *) and are ionized by Kontäktionisierung. 4. Ion source according to claim 1, 2 or 2 characterized by using them in an on the principle of a mass spectrometer working facility for the separation of uranium isotopes 109885/1040 Blank page