RU2447537C1 - Method for manufacturing of electron emitters and device for its implementation - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: method for electron emitters manufacturing of wolfram with alloy additives consists of the following: mixture of wolfram hexafluoride, hydrogen and volatile fluoride or iodide of alloy additive is added to vacuum chamber in ratio corresponding to preset composition of emitter; the mixture is exposed to laser beam action and reaction products are evacuated from the chamber at that emitter is formed by deposition of reduced wolfram and alloy additive to substrate made of wolfram and located in the laser beam centre at the holder while moving the substrate in regard to laser with speed equal to the rate of wolfram and alloy additive deposition.

EFFECT: increase of electron emitters operation life due to homogenous distribution of alloy additives with lower electronic work function than the same value for wolfram; reduction of emitter erosion due to elimination of oxidation; increase of alloy additive concentration and possibility to regulate this concentration, regulation of wolfram structure, reduction of material consumption.

19 cl, 2 dwg, 1 tbl, 3 ex

Description

The invention relates to the manufacturing technology of macro- and micro-products - electron emitters with a reduced electron work function and with a long service life, intended for thermionic elements of electric arc cathodes of plasma generators and thermionic cathodes of vacuum or gas-filled devices that are an electron source.

As a material for the manufacture of thermionic elements of the cathodes of electric arc generators of technological plasma flows, as well as thermionic cathodes of vacuum or gas-filled devices, tungsten is most widely used: tungsten cathodes have the highest melting points (3420 ° C), boiling (5620 ° C), and current density thermal emission at the melting temperature, the lowest evaporation rate. In addition, tungsten has a high heat of fusion, high mechanical strength, thermal conductivity, which is especially important for the operation of cathodes in non-stationary modes. However, tungsten is characterized by a relatively high electron work function (eφ = 4.54 eV); therefore, the operation of a pure tungsten cathode requires a high temperature close to the melting temperature. The life of the electrodes is highly dependent on the operating temperature. In order to increase the service life by lowering the operating temperature, alloying additives are introduced into the tungsten, which increase the emissivity of the cathode (V.F. Gordeev, A.V. Pustogarov. Thermionic arc cathodes. - M.: Energoatomizdat, 1988, 193 p.)

Oxides of thorium (ThO ₂ - eφ = 3.0 eV), lanthanum (La ₂ O ₃ - eφ = 2.96 eV), yttrium (Y ₂ O ₃ - eφ = 3.30 eV), zirconium (ZrO ₂ - eφ = 3.97 eV), hafnium (HfO ₂ - eφ = 3.84 eV), cerium (CeO ₂ - eφ = 2.7 eV), neodymium (Nd ₂ O ₃ - eφ = 3.88 eV), gadolinium (Gd ₂ O ₃ - eφ = 3.96 eV ), ytterbium (Yb ₂ O ₃ - eφ = 4.05 eV), barium (BaO).

The formation of tungsten cathode emitters or cathodes themselves with alloying additives is a complex technological process, for example, the METHOD FOR PRODUCING METAL POROUS CATHODES is known, which involves preparing a mixture of a certain fractional composition from tungsten powder with an average grain size of 3.57 μm, pressing, sintering and impregnation with a substance emitting electrons - a dopant. The purpose of the invention is to increase the yield of suitable cathodes and uniformity of emission ability (RF Patent No. 1619727, op. 20.12.95, C22C 1/08).

In the patent of the Russian Federation No. 2290969, op. 01/10/07 emitter of micron and submicron level is made of tungsten wire by photo-etching.

In the patent of the Russian Federation No. 413753, op. 06/25/77 tungsten carbide is coated on the surface of a flat thoriated tungsten emitter by the reduction of tungsten hexafluoride with hydrogen in the presence of hydrocarbons. The emitter is then mounted inside a copper tube.

Also known is a method of manufacturing emitters of thermionic elements of the cathodes for electric arc plasma generators (plasmatrons). An emitter with a diameter of several millimeters and a length of 10-20 mm is machined from a tungsten billet (or tungsten with additives of oxides of lanthanum, yttrium, aluminum and other metals), which is then pressed or sealed into a centrally located cylindrical channel of a copper water-cooled cathode element (V.F. . Gordeev, AV Pustogarov. Thermionic arc cathodes. - M.: Energoatomizdat, 1988, 193 pp.) The disadvantage of this method is:

- a large amount of waste during milling and / or turning of standard tungsten blanks manufactured at metallurgical plants,

- in the manufacture of an alloy of tungsten with alloying additives by metallurgical methods it is technically difficult due to segregation to obtain the optimal concentration of these additives in the emitter from the point of view of the work function,

- at operating temperatures T> 2600-2800 K, oxide additives are reduced to metal, while the released oxygen mechanically goes outside, which in itself introduces defects into the working surface of the emitter and reduces its working life. These defects are enhanced by the formation of relatively volatile tungsten oxides, which contributes to even greater erosion of the emitter.

A known method of producing silicon from gaseous silicon tetrafluoride, comprising exposing silicon tetrafluoride to continuous radiation of a CO ₂ laser in a reaction chamber, the gaseous silicon tetrafluoride being exposed to laser radiation with a power of 2-10 kW at a pressure of 100-200 mm Hg and at the same time, hydrogen and argon are introduced into the reaction chamber during continuous circulation of these gases and the removal of gaseous reaction products, moreover, silicon is deposited inside the chamber, and the interaction of SiF ₄ and H _{2 is} carried out at a molar ratio of 2: 1, respectively.

To implement this method, a device is proposed that contains a CO ₂ laser with a focusing lens, a reaction chamber with optical windows for input and output of a laser beam mounted at the ends of the chamber, the introduction of gaseous silicon tetrafluoride and hydrogen into the reaction chamber is made in the form of a pipe consisting of two tubes, coaxially located one in the other, and mounted in the middle of the camera on the same axis with the focus point of the laser beam and a silicon trap, while the inner tube serves to introduce silicon trafluoride, external for introducing hydrogen, nozzles for introducing argon are installed at the edges of the reaction chamber, a nozzle for removing reaction gases is installed at the bottom of the chamber, connected to a vacuum pump and filter (RF Patent No. 2066296, C01B 33/03, publ. 10.09. 96).

At present, there is no technology for producing a tungsten emitter of electrons doped with additives, macro- or micro-size “by measure”, i.e. without subsequent mechanical processing, which would make it possible to obtain an emitter of a given size, composition and structure in a single technological process.

The technical result that the invention provides is to increase the service life of tungsten electron emitters due to the homogeneous distribution of dopants with lower electron work function than tungsten, reduce emitter erosion by eliminating oxidation, increase and the ability to control the concentration of dopants, adjust the structure tungsten, reduced material consumption.

To achieve this result, a method for manufacturing an electron emitter from tungsten with dopants is proposed, which consists in introducing into the vacuum chamber a mixture of tungsten hexafluoride, hydrogen and volatile fluoride or dopant iodide in a ratio corresponding to a given emitter composition, they act on the specified mixture with a laser beam and the reaction products are removed from the chamber, and an emitter is formed by depositing reduced tungsten and a dopant on a substrate made of tungsten, and displacements of the center of the laser beam on the carrier, moving the substrate relative to the laser at a rate equal to the rate of precipitation and tungsten dopant.

In this case, an emitter of a given size is formed in the recess of the holder, made in the form of a cathode element.

In this case, the substrate in the form of a disk is placed on the bottom of the recess of the cathode element.

A mixture of tungsten hexafluoride, hydrogen and volatile fluoride or dopant iodide is injected into the recesses in the cathode element.

Tungsten hexafluoride is heated to 18 ° C, a temperature close to the boiling point of tungsten hexafluoride.

Volatile molybdenum hexafluoride heated to a temperature not lower than 40 ° C — a temperature close to the boiling point of molybdenum hexafluoride — is used as an alloying additive.

Volatile niobium pentafluoride heated to a temperature not lower than 235 ° C — a temperature close to the boiling point of niobium pentafluoride — is used as an alloying additive.

Volatile tantalum pentafluoride heated to a temperature not lower than 230 ° C — a temperature close to the boiling point of tantalum pentafluoride — is used as an alloying additive.

As a dopant, volatile titanium tetrafluoride is used, heated to a temperature not lower than 286 ° C, a temperature close to the boiling point of titanium tetrafluoride.

As a dopant, volatile zirconium tetraiodide is used, heated to a temperature not lower than 418 ° C - a temperature close to the boiling point of zirconium tetraiodide.

As a dopant, volatile hafnium tetraiodide is used, heated to a temperature not lower than 418 ° C - a temperature close to the boiling point of hafnium tetraiodide.

As a dopant, volatile lanthanum triiodide is used, heated to a temperature not lower than 1580 ° C - a temperature close to the boiling point of lanthanum triiodide.

Also proposed is a device for the manufacture of an emitter of electrons from tungsten with dopants, consisting of a laser, a vacuum chamber with optical windows for input and output of a laser beam, a pipe for the removal of reaction gases connected to the filter, a pipe for supplying hydrogen and volatile compounds of tungsten and dopants, at the same time, inside the chamber, on the axis of the laser beam, a substrate made of tungsten and mounted on a holder mounted to move in the direction perpendicular to it is mounted the laser beam.

The movement is carried out using a positioning device mounted on a vacuum chamber.

The holder is made in the form of a cathode element with a central recess corresponding in shape and size to the emitter.

In this case, the substrate, made in the form of a tungsten disk, is located at the bottom of the recess of the cathode element.

In this case, the diameter of the laser beam is equal to the diameter of the recess.

The vacuum chamber can be made of monel metal.

In addition, the supply pipe of hydrogen and volatile compounds of tungsten and alloying additives is connected to the injector located in the chamber, the output end of which is located near the recess in the cathode element.

In addition, an absorber for trapping hydrogen fluoride and a column for trapping iodine or hydrogen iodide can be installed behind the filter.

Figure 1 is a General diagram of the device, where 1 is a laser; 2 - laser beam; 3 - optical window; 4 - a vacuum chamber; 5 - pipe input reagents; 6 - mixer; 7 - pipeline; 8, 15, 18 - flowmeters; 9, 14, 17, 20, 25 - valves; 10 - a container with tungsten hexafluoride; 11, 12 - heaters; 13 - container with a fluoride (iodide) dopant; 16 - manovacuum meter; 19 - pipe outlet of the reaction gases; 21 - cermet filter; 22 - positioning device; 23 - an absorber; 24 - pipe exhaust; 26 - to the vacuum line.

Figure 2 shows a manufacturing diagram of an electron emitter on a holder in the form of a cathode element, where

27 - cathode element; 28 — cathode cooling cavity; 29 - tungsten disk; 30 - injector for introducing reagents into the recesses of the cathode element.

The manufacturing process of emitters is based on the use of laser beam treatment of the substrate surface, to which a mixture of volatile tungsten hexafluoride with hydrogen is continuously supplied, to which a volatile compound of a tungsten alloying element is mixed in a predetermined ratio.

The laser beam can be formed using a CO ₂ laser operating at a wavelength of 10.6 microns, or using an Ar ⁺ laser operating at a wavelength of 514 nm, or using an Ar ⁺ laser operating at a wavelength of 480 nm, or with using a Kr ⁺ laser operating at a wavelength of 647.1 nm, or using a ruby laser operating at a wavelength of 1000 nm.

Volatile fluorides or rare metals with a lower work function than tungsten or relatively volatile and thermodynamically unstable metal alloy iodides are used as a volatile compound of a dopant. A laser beam concentrated on a substrate heats it to a sufficiently high temperature; a stoichiometric homogeneously mixed mixture of tungsten hexafluoride with hydrogen and a volatile compound of a tungsten alloying metal is brought to this site. The substrate for growing a tungsten electron emitter from a mixture of tungsten hexafluoride, hydrogen and volatile fluoride (iodide) alloy metal during laser heating can be a thin tungsten disk covering the bottom of the recess in the cathode element or a tungsten wire. As the size of the applied material of the emitter increases, the spot of the laser beam should shift, which is achieved by moving the camera relative to the laser.

In this case, the tungsten and the alloying metal are simultaneously reduced and the alloy is ultimately deposited on the substrate in the form of a cylindrical emitter of tungsten homogeneously alloyed with the additive metal. As an example, consider the process of alloying tungsten with molybdenum or producing a tungsten-molybdenum alloy. This process is described by the equation:

,

,

where W (nMo) is either an alloy of tungsten with molybdenum or, at a relatively low partial pressure of molybdenum hexafluoride, tungsten homogeneously doped with molybdenum having a lower work function than pure tungsten.

The following metals were used as alloying tungsten (eφ = 4.54 eV): molybdenum (eφ = 4.3 eV) in the form of volatile molybdenum hexafluoride, tantalum (eφ = 4.12 eV) in the form of volatile tantalum pentafluoride, niobium (eφ = 3.99 eV) in the form of volatile pentafluoride niobium, titanium (eφ = 3.95 eV) in the form of volatile titanium tetrafluoride, zirconium (eφ = 3.9 eV) and hafnium (eφ = 3.53 eV) in the form of volatile zirconium and hafnium iodides, lanthanum (eφ = 3.3 eV) in the form of lanthanum triiodide vapor . If necessary, it is possible to use aluminum (eφ = 4.25 eV) in the form of volatile aluminum triiodide and tin (eφ = 4.38 eV) in the form of volatile tin tetraiodide as an alloying additive.

Table 1 summarizes the physical properties of tungsten, alloying tungsten metals and their starting materials; Based on these data, the initial parameters of the processes for producing tungsten electron emitters doped with additives with a lower electron work function are determined.

The method is as follows.

Into a pre-evacuated chamber 4, which can be made of monel metal, corrosion-resistant to fluoride and fluoride, with a substrate located in it, for example, a tungsten disk 29 mounted on a holder, for example, a cathode element 27, it is introduced from below through a pipe 5 with a flow meter 18, a mixture of the corresponding volatile fluoride with hydrogen so that it is directed towards the substrate. In the upper part of the chamber is placed a pipe 19 for the removal of reaction gases. In the front wall of the chamber, a window 3 is made of optically transparent and corrosion-resistant material for introducing a beam 2 of laser 1 (two other windows are located on other walls of the chamber); the camera can be located on the positioning device 22, making it possible to move it along three coordinate axes. For evacuation used a vacuum pipe 26 with valve 25.

The condensed tungsten hexafluoride in the container 10 was brought into a gaseous state by heating it using a heater 11, and fed through a valve 9 and a flow meter 8 through a pipe 7 to a mixer 6. There, fluoride or dopant iodide from a container 13 was supplied through a valve 14 and a flow meter 15.

The calculated amount of hydrogen was supplied to the mixer 6 through the valve 17 and the hydrogen flow meter 18 to obtain a homogeneous gas mixture of a given composition. The temperature of the mixer 6 should always be higher than the temperature of the evaporator of tungsten hexafluoride and should correspond to the temperature of evaporation or sublimation of the fluoride or iodide of the dopant (Table 1) taking into account the required partial pressure of this additive. The same applies to the temperature of the vacuum chamber itself and the connecting pipes. The pressure in the communications is measured by manovacuum meters 16. The reaction mixture can be fed directly through the injector 30 into a recess in the cathode element.

In the process of growing an electron emitter, reduction by-products are formed, consisting mainly of gaseous hydrogen fluoride. They are sent from the chamber 4 through a pipe 19, for example, to a cermet anisotropic filter 21. Hydrogen fluoride is trapped completely either in the absorber 23 or in a sorption column filled with granules of a solid fluoride sorbent. When iodides of alloying elements are used, impurities of iodine or hydrogen iodide appear in the hydrofluoric exhaust; in this case, in addition to the absorber (sorption column) 23, an additional column is installed for collecting iodine or hydrogen iodide (for example, a condenser cooled by an appropriate refrigerant is not shown). Further, exhaust products are discharged along line 24.

The process of growing an electron emitter proceeds as follows. They turn on the heating of containers 10 and 13, vacuum the chamber 4 and all communications, turn on the laser 1. The laser beam 2 is directed through an optical window 3 to a copper cathode element 27, in the center of which a recess is machined - a cylindrical channel with specified dimensions for growing an electron emitter in it.

Due to the high thermal conductivity of copper, a thin tungsten disk 29 is densely pressed onto the channel bottom, and a laser beam is directed onto the surface of the disk so that its diameter matches the diameter of the disk. A cooling cavity 28 is made in the cathode element.

On the disk of tungsten 29 begins the process of deposition of tungsten with alloying additives.

The emitter formation process proceeds with a gradual removal of the formed surface from the laser. The removal rate corresponds to the deposition rate of the emitter material.

The mixture (WF ₆ + xH ₂ + MeHal _n ), having a stoichiometric composition with respect to tungsten, hydrogen and alloying components, enters from the mixer 6 through the nozzle 5 and is injected by the injector 30 at such a speed that it reaches the bottom of the cathode element 27 in the spot of the laser beam. Estimates of the speeds of the laser process show that the time for which the mixture must reach the substrate is in the range of 0.001-0.01 s.

The gas mixture must be transparent to the laser. Analysis of the absorption spectra of gaseous fluorides of tungsten, molybdenum, tantalum and other metals shows that a number of lasers can be used to fabricate the above electronic emitters:

- CO ₂ laser operating at a wavelength of 10.6 microns;

- Ar ⁺ laser operating at a wavelength of 514 nm and a wavelength of 480 nm;

- Kr ⁺ laser operating at a wavelength of 647.1 nm;

- ruby laser operating at a wavelength of 1000 nm;

To ensure camera movement along three coordinate axes, it is equipped with a Burleigh X-Y-Z micro-positioning device, which has a linear accuracy of movement better than 0.1 microns.

Example 1

The reactor, shown schematically in FIGS. 1, 2, is used for the manufacture of cathode elements of 100-200 kW electric arc plasmatrons equipped with an electronic emitter made of an alloy of tungsten with molybdenum, in which 80% by weight. tungsten and 20% molybdenum. The work function of tungsten (eφ = 4.54 eV) was used to dope tungsten with molybdenum (eφ = 4.3 eV). The raw material for alloying is molybdenum hexafluoride. The dimensions of the cylindrical channel in a copper holder - cathode element: 4 mm in diameter 20 mm length, a disk made of tungsten is tightly pressed into the bottom of the channel. The size of the copper cathode element is 20 mm in diameter, 40 mm in length. The dimensions of the vacuum chamber of the reactor are 60 × 60 × 60 mm. The diameter of each of the 3 optical windows of the camera is 40 mm. The camera is mounted in a Burleigh X-Y-Z micro-positioning device with linear accuracy above 0.1 microns.

The temperature of the container with tungsten hexafluoride 18 C; the temperature of the container with molybdenum hexafluoride, a mixer, connecting lines and the walls of the reactor is 40 C. The reactor was evacuated to a residual pressure of ~ 0.001 Pa before the start of the process. The process of deposition of doped tungsten was carried out in a continuous mode.

For work, we used a CO ₂ laser operating at a wavelength of 10.6 microns; laser power - 0.705-1.310 kW.

The temperature of the tungsten disk in the spot focus of the laser beam was 810 ° C at a power of 1.310 kW, the pressure in the reactor after introducing a stoichiometric mixture of tungsten, molybdenum and hydrogen hexafluorides into it was 90 kPa. Under these conditions, polycrystalline tungsten and molybdenum are deposited at a rate of ~ 120 μm / min. At the same speed, the microposition device moved the reactor away from the laser so that the focus of the laser beam was concentrated all the time on the surface of the emitter. TEM photomicrographs of the polycrystal extracted from the channel show that the grains reach ~ 10 μm, i.e. the grown preform had a nanocrystalline structure. The emitter length was ultimately 20 mm, diameter 4 mm. The total growing time is 198 min = 3.3 hours.

The morphology of the obtained product was determined using a scanning (scanning) electron microscope. To determine the phase composition of the product using transmission electron microscopy (TEM - Transmission Electron Microscopy), which allows to determine the phase distribution. It was established that molybdenum was distributed homogeneously in the body of the electron emitter in both diameter and length.

The work function of the electrons from the grown (W-Mo) - alloy was determined by the contact potential difference (CRP) method. It was found that during the cathode operation, the electron work function corresponded to the calculated value of 4.2 eV.

Example 2

The reactor, shown schematically in FIGS. 1, 2, is used for the manufacture of cathode elements of 100-200 kW electric arc plasmatrons equipped with an electronic emitter made of an alloy of tungsten with tantalum, in which 80% by weight. tungsten and 20% tantalum. The work function of tungsten (eφ = 4.54 eV) for doping tungsten was used tantalum (eφ = 4.12 eV). The raw material for alloying is tantalum pentafluoride. The dimensions of the cylindrical channel in a copper holder - cathode element: 4 mm in diameter, 20 mm in length, a disk made of tungsten is tightly pressed into the bottom of the channel. The size of the copper cathode element is 20 mm in diameter, 40 mm in length. The dimensions of the reactor chamber are 60 × 60 × 60 mm. The diameter of each of the 3 optical windows of the camera is 40 mm. The temperature of the container with tungsten hexafluoride 18 C; the temperature of the container with tantalum pentafluoride, a mixer, connecting communications and the walls of the laser reactor is 230 ° C. Before the start of the process, the reactor was evacuated to a residual pressure of ~ 10 ^-3 Pa. The process of deposition of doped tungsten was carried out in a continuous mode. For work, we used a CO ₂ laser operating at a wavelength of 10.6 microns; laser power - 0.705-1.310 kW.

The temperature of the tungsten disk in the spot focus of the laser beam was 1.310 kW at 813 ° C, and the pressure in the reactor after entering a stoichiometric mixture of tungsten hexafluoride, tantalum pentafluoride, and hydrogen was 89 kPa. Under these conditions, polycrystalline tungsten and tantalum are simultaneously deposited at a rate of 110 μm / min. At the same speed, the microposition device moved the reactor away from the laser so that the focus of the laser beam was concentrated all the time on the surface of the emitter. TEM microphotographs of the polycrystal show that the grains reach ~ 10 μm, i.e. the grown emitter had a nanocrystalline structure. The length of the micro rod was ultimately 20 mm, diameter 4 mm. The time for growing the rod is 242 min = 4.03 hours.

It was established that during the operation of the cathode obtained by the W-Ta polycrystalline alloy, the electron work function corresponded to the calculated value of 4.12 eV.

Example 3

The reactor, shown schematically in FIGS. 1, 2, is used for the manufacture of cathode elements of 100-200 kW electric arc plasmatrons equipped with an electronic emitter made of an alloy of tungsten with hafnium, in which 87% by weight. tungsten and 13% hafnium. The work function of tungsten (eφ = 4.54 eV) was used for doping tungsten with hafnium (eφ = 3.53 eV). The starting material for alloying is hafnium tetraiodide. The dimensions of the cylindrical channel in the copper holder of the cathode element: 4 mm in diameter, 20 mm length, a washer made of tungsten is tightly pressed into the bottom of the channel.

The process conditions and dimensions of the cathode, as in the previous examples. The temperature of the container with tungsten hexafluoride 18 C; the temperature of the container with hafnium tetraiodide, mixer, communications and walls of the laser reactor 400 ° C. The temperature of the tungsten disk in the spot focus of the laser beam was 1.310 kW at 817 ° C, and the pressure in the laser reactor after entering a stoichiometric mixture of tungsten hexafluoride, hafnium tetraiodide and hydrogen was 89 kPa. Under these conditions, polycrystalline tungsten and hafnium are simultaneously deposited at a rate of 145 μm / min. At the same speed, the microposition device moved the reactor away from the laser. TEM - micrographs of a polycrystal show that grains reach ~ 10 μm, i.e. the grown emitter had a nanocrystalline structure. The emitter length was ultimately 20 mm, diameter 4 mm. The time for growing the rod is 188 min = 3.13 hours.

It was established that during the operation of the cathode obtained by the W-Hf polycrystalline alloy, the electron work function corresponded to the calculated value of 3.53 eV.

Thus, this invention will allow in one technological process to obtain emitters for thermionic elements of electric arc cathodes of plasma generators and thermionic cathodes of vacuum or gas-filled devices that are a source of electrons. At the same time, the service life of tungsten electron emitters increases due to the homogeneous distribution of dopants with lower electron work function than tungsten, emitter erosion due to elimination of oxidation is reduced, it becomes possible to control the concentration of dopants, and to regulate the structure of tungsten.

Claims (19)

1. A method of manufacturing an emitter of electrons from tungsten with dopants, which consists in the fact that a mixture of tungsten hexafluoride, hydrogen and volatile fluoride or dopant iodide in a ratio corresponding to a given emitter composition is introduced into the vacuum chamber, a laser beam is applied to the said mixture and products are removed reactions from the chamber, while forming an emitter by depositing reduced tungsten and a dopant on a substrate made of tungsten and placed in the center of the laser beam on the holder, while moving the substrate relative to the laser at a speed equal to the deposition rate of tungsten and dopant. 2. The method according to claim 1, characterized in that the emitter of a given size is formed in the recess of the holder, made in the form of a cathode element. 3. The method according to claim 2, characterized in that the substrate in the form of a disk is placed on the bottom of the recess of the cathode element. 4. The method according to claim 2, characterized in that the mixture of tungsten hexafluoride, hydrogen and volatile fluoride or dopant iodide are injected into the recesses in the cathode element. 5. The method according to claim 1, characterized in that the tungsten hexafluoride is heated to 18 ° C, a temperature close to the boiling point of tungsten hexafluoride. 6. The method according to claim 1, characterized in that as a dopant, volatile molybdenum hexafluoride is used, heated to a temperature of at least 40 ° C — a temperature close to the boiling point of molybdenum hexafluoride. 7. The method according to claim 1, characterized in that as a dopant, volatile niobium pentafluoride is used, heated to a temperature not lower than 235 ° C — a temperature close to the boiling point of niobium pentafluoride. 8. The method according to claim 1, characterized in that as a dopant, volatile tantalum pentafluoride is used, heated to a temperature of at least 230 ° C — a temperature close to the boiling point of tantalum pentafluoride. 9. The method according to claim 1, characterized in that as a dopant, volatile titanium tetrafluoride is used, heated to a temperature not lower than 286 ° C — a temperature close to the boiling point of titanium tetrafluoride. 10. The method according to claim 1, characterized in that as a dopant, volatile zirconium tetraiodide is used, heated to a temperature not lower than 418 ° C — a temperature close to the boiling point of zirconium tetraiodide. 11. The method according to claim 1, characterized in that as a dopant, volatile hafnium tetraiodide is used, heated to a temperature not lower than 418 ° C — a temperature close to the boiling point of hafnium tetraiodide. 12. The method according to claim 1, characterized in that as a dopant, volatile lanthanum triiodide is used, heated to a temperature not lower than 1580 ° C — a temperature close to the boiling point of lanthanum triiodide. 13. A device for manufacturing an emitter of electrons from tungsten with dopants, consisting of a laser, a vacuum chamber with optical windows for input and output of a laser beam, a pipe for the removal of reaction gases connected to the filter, a pipe for supplying hydrogen and volatile compounds of tungsten and dopants, while inside the chamber on the axis of the laser beam, a substrate is made perpendicular to it, made of tungsten and mounted on a holder, mounted to move in the direction of the laser beam. 14. The device according to item 13, wherein the movement is carried out using a positioning device mounted on a vacuum chamber. 15. The device according to item 13, wherein the holder is made in the form of a cathode element with a Central recess, in shape and size corresponding to the emitter. 16. The device according to p. 15, characterized in that the substrate is made in the form of a tungsten disk located at the bottom of the recess of the cathode element. 17. The device according to p. 15, characterized in that the diameter of the laser beam is equal to the diameter of the recess. 18. The device according to p. 15, characterized in that the pipe for supplying hydrogen and volatile compounds of tungsten and alloying additives is connected to an injector located in a vacuum chamber, the output end of which is located near the recess in the cathode element. 19. The device according to claim 13, characterized in that the filter has an absorber for trapping hydrogen fluoride and a column for trapping iodine or hydrogen iodide.

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