RU73875U1 - COLD CATHODE - Google Patents

Abstract

ESSAY

The utility model relates to electronic technology, and more specifically, to its areas where the physical phenomenon of electronic or ion-electron or field emission is used and relates to the cold cathode.

A cold cathode of metal or alloy is proposed having a mixed structure containing grains and fragments of nanometric size, obtained by intensive plastic deformation, characterized in that the cathode has a mixed structure containing from 50 to 95% grains of nanometer size, the rest of the fragments, or grain structure containing nanometer-sized grains obtained by intensive plastic deformation and subsequent low-temperature annealing at a temperature not lower than the operating temperature Toda.

The utility model is an improvement in the cold cathode, the structure of which is obtained by means of intense plastic deformation and can further increase the efficiency of the cathode by reducing the electron work function.

Description

2420-300935RU / 032

COLD CATHODE

The utility model relates to electronic technology, and more specifically, to its areas where the physical phenomenon of electronic or ion-electron or field emission is used, and relates to the cold cathode.

Cold cathodes operating on the principle of secondary electron or ion-electron emission, or field emission, are widespread. They are used in devices such as vacuum and gas-discharge devices, including optical quantum generators, helium-neon lasers, indicator devices, and ion sources. In particular, the latter are, in turn, an important component of widely used devices: plasmatrons, mass spectrometers. The characteristics of cold cathodes determine the accuracy and efficiency of the above devices. The requirements for the characteristics of cold cathodes increase with the development of microelectronics and nanoelectronics.

In most of the devices listed above, cold cathodes use cathodes made of metals and alloys: aluminum, beryllium, magnesium, iron, nickel, tantalum, molybdenum, etc. [1]. The choice of a certain cathode material is carried out, guided by the requirements for its durability and efficiency, in the latter case, taking into account such a most important emission characteristic of a metal or alloy as the electron work function. Other things being equal, a decrease in the electron work function allows one to obtain, for example, a larger ion current in an ion source with a lower value of the applied voltage. In addition, for example, in gas-discharge devices, decreasing the value of the work function allows reducing the gas pressure and thereby reducing the load on the vacuum system of the device, which ultimately leads to an increase in the reliability of the device.

The values of the electron work function for various materials, including metals, are given in the reference literature [2].

Known cold cathode of a gas-discharge device [3], made of practically pure aluminum, into which an additive of silicon in the amount of 0.5-1.65 masses is introduced. %

The silicon additive in aluminum promotes the formation of a homogeneous microstructure and grain size reduction, which in turn contributes to an increase in the stability of the oxide layer and prevents the cathode from sputtering.

Known cold cathode [4], the material of which, in contrast to [3] also contains iron in an amount of 0.1-2.0 mass. % The introduction of an iron additive in an alloy of aluminum with silicon reduces the lattice parameters due to the formation of a homogeneous substitutional solid solution in aluminum. In this case, the resistance to ion bombardment of the cathode surface increases, and sputtering is further reduced.

Known cold cathode of a gas-discharge device, in which nickel is used as the cathode material with the addition of cesium or rubidium aluminosilicate in an amount of 0.5-25 mass. % [5], which provides the possibility of stable operation of the cathode in conditions of intense ion bombardment, increases the emission current, including by reducing the output work.

The disadvantage of the methods associated with changing the composition of the alloy by introducing special additives [3, 4, 5] is the inability to manufacture a cathode with predetermined properties with a high degree of accuracy, which is due to the fact that it is almost impossible to maintain the same composition with different melts alloy. That is why, in known solutions, the amount of additives is given in a fairly wide range. Such cathodes cannot be interchangeable when used in the above-mentioned modern devices. In addition, changing the composition of any industrial alloy is economically extremely disadvantageous.

In connection with the last statement, the use of industrial aluminum alloys of type D 16, mass. %: Al - basic; Cu - 4.3; Mg - 1.5; Mn 0.6; Fe ≤ 0.5; Si ≤ 0.5, and AD 1 (technically pure aluminum, 99.3%) as a cold cathode material [6]. The cathode has a surface hardened by cold plastic deformation, namely, ball rolling. Such a hardened surface enhances cathode durability.

Known cathode (cathode target) [7], made of metal or alloy, having a homogeneous fine-grained, with a grain size of 15 μm and above, the structure in the entire volume. Such a structure in the cathode is obtained due to plastic deformation (rolling) of the cathode blank.

Due to the homogeneous fine-grained structure, uniformity of metal sputtering from the target surface is achieved. But the known solution [7] does not reflect how the cathode structure, in particular, the grain size obtained by plastic deformation, can affect the electron work function and cathode strength.

The effect of plastic deformation under various conditions of a stress-strain state on the electron work function is known from [8]. A technique is proposed for calculating the change in the work function based on the model of its relationship with the electronegativity of metals, taking into account the formation of nanometric surface defects. However, the possibilities of using the model and the calculation procedure based on it in the manufacture of the cathode, characterized by a lower value of the work function, are also limited. The reason for this is, first of all, that the technique, being quite complex and cumbersome, takes into account the influence on the change in the work function of the output only of surface defects, which can be neutralized during further processing of the cathode or during its operation.

Moreover, from [8] it is known that a decrease in the work function corresponds to an increase in the degree of plastic deformation.

It is known that the maximum possible degree of deformation without destroying the workpiece allows the implementation of special methods of intensive plastic deformation (IPD) [9,10].

The most well-known special SPD methods include equal-channel angular pressing (ECG-pressing) and torsion under quasi-hydrostatic pressure in a Bridgman type anvil type installation [9,10]. Using these methods, a degree of deformation of e ≥ 4 can be achieved, where e is the true logarithmic degree of deformation.

Based on the foregoing, a cold cathode, known from [11], was selected as a prototype of a utility model. The cathode is made of tungsten with a purity of 99.99% and has a structure with a nanometric grain size of about 100 nm, which was obtained due to the SPD carried out, in particular, by torsion under quasi-hydrostatic pressure in a Bridgman type anvil type installation to the true logarithmic degree e ~ 7.

By measuring the contact potential difference, the electron work function is determined, more precisely, the difference between the work function of the cathode sample subjected to SPD and having a nanometric grain size and the work function of the cathode sample in the usual coarse-grained state. It was found that the formation of a structure with a nanometric grain size leads to a decrease in the work function in the metal. The decrease in the work function for tungsten with a grain size of about 100 nm was ~ 0.8 eV. Complex studies of the sample were carried out, including transmission electron microscopy, as well as numerical simulation of the experiment.

It was found that the specific behavior of the nanocrystalline material under consideration is determined, first of all, not by a small grain size, but by a special, characterized by internal stresses, “nonequilibrium” state of grain boundaries, as evidenced by the diffuse contrast at the grain boundaries observed by means of an electron transmission microscope. Moreover, significant, up to 1-3%, lattice distortions by internal stresses were observed near the boundaries in a region with a width of the order of 10 nm.

Thus, it was possible to hypothesize that the formation of a structure with a nanometric grain size leads to the appearance of current tubes with a reduced work function. Such a current tube directly includes grain boundaries and their surroundings with a width of about 10 nm.

In addition to reducing the work function, the SPD leads to a noticeable increase in the strength of the cold cathode, which can lead to an increase in its durability [6].

However, further experiments showed that an increase in the degree of deformation, in particular, of a sample from the same tungsten, during SPD does not give the expected decrease in the work function, known from [8]. And when deformed by the IPD method, in particular, of a sample from an industrial aluminum alloy AMG6 (6.3% Mg; 0.6% Mn; Cu <0.1%; Zn <0.2%; Fe <0.4; Si < 0.4%, the rest Al) generally fails to obtain the expected result in accordance with [11].

Thus, there is a problem associated with the identification of a clear relationship between the value of the electron work function in the cathode and its structure, characterized by the nanometric grain size obtained by SPD.

The objective of the utility model is to increase the efficiency of a cathode made of metal or alloy by reducing the electron work function by modifying the cathode structure obtained after SPD.

The problem is solved when the cold cathode of a metal or alloy having a mixed structure containing grains and fragments of nanometric size, obtained by intensive plastic deformation, differs from the known fact that the cathode has a mixed structure containing from 50 to 95% grains of nanometric size, the rest of the fragments, or a grain structure containing grains of nanometric size, obtained by intensive plastic deformation and subsequent low-temperature annealing erature is not lower than the operating temperature of the cathode.

Utility Model Explanation

Investigations by electron microscopy of samples subjected to SPD have shown that, under intense plastic deformation, the structure of a metal or alloy undergoes significant modifications. Grain division occurs with the formation of smaller than the initial grains, fragments - disoriented areas separated by unformed dislocation-type boundaries. In the process of recrystallization, fragments are transformed into grains of approximately the same size as the fragments, with the formation of grain-type boundaries between them. In this case, the formation of grains and corresponding boundaries in pure metals is more intense than in alloys, due to the migration of boundaries difficult in alloys. Next, there is a division of the newly formed grains. These processes during the time of the IPD implementation occur simultaneously and continuously. Therefore, at the time when the required nanometric size of the structural elements is reached, when the SPD is interrupted, both grains and fragments of nanometric size are inevitably present in the metal or alloy. Thus, the metal or alloy after the SPD has a mixed structure, at best, containing an equal number of grains and fragments, as, for example, in metals, or a predominant, more than 50%, number of fragments, as, for example, in alloys. The first picture was revealed, in particular, during additional studies of the structure of the sample from tungsten, and the second - during studies of the structure of the sample from aluminum alloy AMG6.

Moreover, an increase in the degree of deformation above a certain value depending on the physical properties of the metal or alloy does not lead to the transformation of the fragmented structure into a grain structure and to an increase in the fraction of grain boundaries. For this reason, both alloys and pure metals, after SPD, can have a structure containing mainly fragments of nanometric size. The boundaries of the fragments are of a dislocation nature, that is, they are not crystallographically formed, and remain so during and after deformation (see Fig. 10 below, illustrating the considered structure of a cathode sample from AMG6 alloy). Accordingly, such unformed boundaries cannot provide an additional decrease in the electron work function. Moreover, the work function in the cathode samples with a structure containing less than 70 - 80% of the grains may not differ in value from the work function in the cathode samples with a coarse-grained structure obtained by traditional methods.

During low-temperature annealing, the fragmented structure is transformed into a grain structure. The temperature and annealing time are selected from the condition of preservation of the nanometric grain size.

Annealing temperature, sufficient only for the conversion of fragments into grains, does not lead to an increase in the size of structural elements. The nanometric grain size remains approximately equal to the size of the fragments. Since it is almost impossible to achieve absolute equality in the sizes of grains and fragments in such a physical process as the transformation of the structure of a metal or alloy, the grain size by several nanometers, within ~ 20 - 30 nm, can be larger than the sizes of fragments. The boundaries of the formed nanometer-sized grains make an additional contribution to the decrease in the electron work function compared to the contribution that only the SPD gives in the case of a partially fragmented structure, such as, for example, for a tungsten cathode. In the presence of a predominantly fragmented structure after SPD, only annealing can provide the effect of decreasing the value of the work function known from [11].

Ensuring, due to SPD and subsequent low-temperature annealing, the presence of at least 50% nanometer-sized grains in the alloy structure, for example, AMG6, already creates a favorable picture of the appearance of current tubes and a decrease in the work function. In pure metals due to IPD and annealing, a structure containing up to 100% nanometer grains can be obtained.

It is recommended that the annealing temperature for most metals and alloys traditionally used for the manufacture of a cold cathode be chosen to be approximately 0.2 Tm. It has been experimentally established that such an annealing temperature is suitable for practically pure metals, such as nickel, tungsten, titanium, molybdenum, and for alloys such as AMG6, E 125 (2.5% Nb; the rest is Zr), etc. Annealing at more low temperature does not lead to noticeable changes in the structure of the deformed sample. In addition, the cold cathode during operation can be warmed up, as a rule, from room temperature to temperatures of the order of 100 ^° C; therefore, the annealing temperature must be at least the working temperature of the cathode in order to avoid thermal instability of its structure during operation.

In combination with low-temperature annealing, SPD can be used to obtain a structure that increases the cathode efficiency from almost any metal or alloy traditionally used for these purposes. Whereas the use of IPD alone cannot lead to an increase in the efficiency of a cathode made of metal or alloy, which is prone to intense fragmentation during IPD.

The use of SPD and low-temperature annealing can increase the efficiency of the proposed cold cathode compared to the prototype by manufacturing a cathode from an industrial alloy without introducing additional additives to reduce the electron work function.

In addition, the utility model retains other advantages of the prototype.

Namely, a utility model allows to increase the strength of the cold cathode. However, compared with traditional coarse-grained cathodes, the increase in strength occurs by a slightly lower value than in the prototype, due to the partial removal of hardening.

IPD methods have certain limitations associated with the small dimensions of the workpieces and the need to give them a certain shape: a bar - for ECA pressing, or a disk - for torsion under quasi-hydrostatic pressure.

However, the aforementioned is not a limitation for the industrial application of the utility model, since the cathode has small dimensions corresponding to the SPD methods and a tendency to further decrease in dimensions. Moreover, there is the possibility of industrial use in combination with low-temperature annealing of such an SPD method, such as torsion under quasi-hydrostatic pressure, which is traditionally considered suitable for processing samples of metals and alloys in laboratory conditions.

It should also be noted that during the operation of the cathode heated to realize the phenomenon of thermionic emission, grain growth occurs, accompanied by relaxation of the energy stored within the boundaries. Therefore, the feature reflected in the name of the utility model, the cold cathode, becomes significant.

Based on the foregoing, we can conclude that the tasks of the utility model are solved only with the interconnected use of the totality of the essential features of the utility model.

The utility model is illustrated by the following graphic materials:

Figure 1. The cathode fabrication scheme;

Figure 2. Experimental sample of a cold cathode (photo);

Figure 3. The appearance of the diode cell (photo);

Figure 4. Gas discharge in a diode cell (photo);

Figure 5. Current-voltage characteristics of a diode cell with a cold nickel cathode;

6. Current-voltage characteristics of the diode cell with a cold cathode of alloy E 125;

7. Current-voltage characteristics of the diode cell with a cold cathode from AMG6 alloy;

Fig. 8. Current-voltage characteristics of a diode cell with a cold tungsten cathode;

Fig.9. Structure of a sample of a cold cathode from an AMG6 alloy before deformation;

Figure 10. The structure of the sample from the cold cathode of the AMG6 alloy after SPD;

11. Structure of a sample of a cold cathode from AMG6 alloy after SPD and annealing at 75 ⁰ С;

Fig. 12. The structure of the sample from the alloy AMG6 after SPD and annealing at 150 ° C;

Fig.13. Structure of a sample of a cold cathode from AMG6 alloy after SPD and annealing at 250 ° С;

Fig.14. Structure of a sample of a cold cathode from AMG6 alloy after SPD and annealing at 300 ° С;

Fig.15. The microhardness of a cold cathode sample as a function of grain size.

Examples of specific performance:

For the manufacture of a cold cathode in accordance with the essential features of a utility model, aluminum, beryllium, iron, nickel, tungsten, tantalum, molybdenum, titanium, niobium, zirconium and other metals or alloys based on them can also be used, for example [1] that is, traditionally used for the manufacture of a cold cathode.

To illustrate the industrial applicability of the utility model, technically pure nickel (Ni 99.98%), technically pure tungsten (99.99%) and industrial aluminum alloys - AMG6, and zirconium - E125 were chosen as the cold cathode material. The given example does not exhaust the possibilities of using all other metals and alloys from which a cold cathode can be made.

In all cases, the cathode blank was deformed by the SPD method - torsion under quasi-hydrostatic pressure at a Bridgman type anvil type installation (Figure 1). In figure 1, position 1 indicates the cathode blank, position 2 - anvil strikers.

The given example also does not exhaust the use of other IPD methods in the manufacture of a cold cathode, including, in the case of their development after the creation of a real utility model.

For IPD, a disk with a diameter of 10 mm and a thickness of 0.2 mm was cut from an industrial hot-pressed bar from an alloy AMG6, as well as ingots from nickel and tungsten, and alloy E 125.

Billets were placed between two strikers and squeezed under pressure P ~ 7 GPa at room temperature.

A structure with elements in the form of mainly fragments in the cathode blanks of alloys E 125 and AMG6, as well as in the form of fragments and grains in the cathode blanks of tungsten and nickel was obtained through intense plastic deformation. The deformation of all the blanks was carried out until the true logarithmic degree e ~ 7 was achieved.

The degree of deformation was determined by the formula:

e = ln (φr / l ),

where θ is the rotation angle in radians, r and l are the radius and thickness of the workpiece, respectively [10].

Using a JEM-2000EX transmission electron microscope, the degree of fragmentation of the workpieces and the sizes of structural elements were determined.

The average size of the fragments and grains in the cathode blanks of nickel and tungsten was 100 nm. At the same time, the degree of fragmentation of the nickel preform was greater than that of the tungsten preform.

The average size of the fragments in the blanks of the cathode of the alloy AMG6 was 100 nm.

The average grain and fragment size in the cathode blank of alloy E125 was 90 nm.

In the last two blanks, the degree of fragmentation was significant.

After deformation, the cathode blanks were subjected to low temperature annealing. Annealing was carried out at the following temperatures:

- for workpieces from AMG6 alloy - 150 ° C;

- for a workpiece from alloy E125 - 300 ° C;

- for nickel billets - 250 ° C;

- for billets made of tungsten - 500 ° C.

Annealing time was ~ 1 hour. The annealing time may be longer or shorter than indicated depending on, respectively, a lower or higher annealing temperature.

After annealing in all cathode samples, a predominantly grain structure was obtained.

Also, using the JEM-2000EX transmission electron microscope, the grain size in the cathode samples and their approximate number were determined.

Accordingly, the average grain size and their approximate amount were

- in the sample cathode from alloy AMG6 - 130 nm, 60%;

- in a sample of a cathode from alloy E125 - 110 nm, 70%;

- in the sample cathode made of Nickel - 120 nm, 80%;

- in a tungsten cathode sample - 120 nm, 100%

To prevent oxidative processes, annealing was carried out in an electric furnace in vacuum.

After deformation and annealing, all four cathode samples were subjected to additional deformation to obtain a slightly convex-concave shape. In this case, the workpieces were deformed at room temperature.

The prepared samples of the cold cathode had a disk shape with a diameter of 10 mm and a thickness of ~ 0.1 mm.

The finished experimental cold cathode sample is shown in FIG. 2. Such a cathode can be used as part of an ion source.

Next, we measured the electron work function.

The work function was measured by the contact potential difference method [12]. The shift of the delay curves relative to each other directly determined the relative change in the work function Δφ for cathode samples having a structure after SPD and low-temperature annealing and for samples having a structure after only SPD. For the reliability of the results, before measuring the work function, we cleaned the surface of all samples directly in the measuring setup, avoiding contact of the sample with air, using ion etching in an inert gas atmosphere.

The measurement error was ~ 2%.

For clarity, the results are summarized in a table:

No. Sample material Δφ = φ ₁ -φ ₂ , eV one Alloy AMG6 0.3 2 Nickel 0.4 3 Alloy E125 0.3 four Tungsten 0.2

φ ₁ and φ ₂ are the electron work function of the proposed cold cathode and prototype, respectively ..

Measurements showed that cathode samples after SPD and low-temperature annealing have a lower work function compared to cathode samples after SPD.

Decreased work function leads to increased efficiency

cold cathode, for example, during its operation as part of an ion source.

An ion source is an electrovacuum device for producing a directed ion flow, the action of which is based on the use of various types of electric discharges in a gas (inert gases, hydrogen) or metal vapors. The simplest ion source is a diode cell, FIG. 3, 4, the cylinder of which is filled with an inert gas, and the properties are determined by the interaction of the electron flow with the gas medium and the electric field between the electrodes (anode and cathode).

The efficiency of an ion source with a cold cathode is characterized by the ability to produce a higher working current of the ion beam at a lower working voltage, as well as a uniform ion beam composition and a constant ion current density. Under the same conditions, the efficiency of the cathode depends on the properties of the cathode material, in particular, on the electron work function. The lower the electron work function, the greater the coefficient of secondary ion-electron emission and, as a consequence, the ion beam intensity.

Studies of the current-voltage characteristics of an independent discharge in a diode cell with the proposed cold cathodes have shown an increase in the efficiency of the cathodes:

- of nickel higher by 55%, see figure 5;

- of alloy E125 higher by 35%, see Fig.6 .;

- from the alloy AMG6 higher by 40%, see Fig.7;

- of tungsten higher by 25%, see Fig. 8.

The current-voltage characteristics of the proposed cold cathodes are shown in FIG. 5, 6, 7, 8.

In FIG. 5, 6, 7, 8 curve 1 - current-voltage characteristic of a diode cell with the proposed cold cathode made of nickel, alloys E125 and AMG6 and tungsten, respectively, and having a structure after SPD and low temperature annealing; curve 2 - current-voltage characteristic of a diode cell with a cold cathode made of the same materials with a structure obtained after SPD without using low-temperature annealing.

As already noted, studies of the microstructure of the samples were carried out using a JEM-2000EX transmission electron microscope. The samples of all four materials were examined: nickel, tungsten, AMG6 alloy, and E125 alloy. In all cases, reliable results were obtained regarding the evolution of the structure in the samples, confirming the possibility of solving the problem of the utility model. For brevity, the following are data (graphic materials) on the AMG6 alloy only.

In FIG. Figures 9, 10, 11, 12, 13, 14 show the cathode structure of the studied alloy AMG6, respectively, before deformation, after deformation, after deformation, and annealing at temperatures T = 75, 150, 250, and 300 ⁰ С.

Before SPD, the AMG6 alloy had a typical partially recrystallized structure of a hot-pressed semi-finished product. Coarse inclusions of primary phases were present in the matrix. Chemical analysis showed that the composition of light particles corresponds to the Al ₁₀ Mg ₂ Mn phase, and that of dark particles corresponds to Mg ₂ Si.

After SPD, the matrix structure acquired a fragmented structure and consisted of fragment elements with an average size of ~ 100 nm. The inhomogeneous contrast in the body of the fragments testified to the presence of strong distortions of the crystal lattice and high internal stresses, and to the dislocation nature of the boundaries and their unformed state.

Annealing at a temperature of 75 ° C did not lead to noticeable changes in the fragmented structure of the alloy.

During annealing at a temperature of 150 ° С, the fragmented structure was transformed into a grain-type structure. The process was accompanied by a slight enlargement of grains (up to ~ 130 nm). With a further increase in temperature to 250 ° C, normal grain growth was activated, forming an equilibrium and equiaxial structure, with an average grain size of ~ 540 nm. A further increase in the annealing temperature was accompanied by a significant enlargement of grains. As a result, after annealing at 300 ° С, the grain size increased to 2 μm.

The obtained data also made it possible to estimate the microhardness of the sample in various structural states. Microhardness was evaluated according to GOST 9450-76.

On Fig shows the dependence of microhardness on the annealing temperature of the alloy AMG6 and, accordingly, on the grain size. According to the obtained dependence, the microhardness of a cold cathode sample subjected to SPD and low-temperature annealing is 2.5 times higher than that of a sample in a coarse-grained state. As a result, the cathode strength is increased 2.5 times, and, as already noted for a number of alloys, its durability. In this case, the microhardness of the sample after SPD and low-temperature annealing is slightly less than after SPD due to the partial removal of strain hardening (hardening).

The sharp decrease in microhardness observed at higher temperatures is caused by the structural transformations described above and is associated with the removal of the effects of strain hardening.

Sources of information taken into account:

1. A.S. SU 375709, IPC H01J 9/02, 1/30 1973.

2. V.S. Fomenko Reference "Emission properties of materials." Kiev, Science. Dumka, 1981.-340s.

3. A.S. SU 1023947, IPC H01J 1/30, 1991.

4. A.S. SU 1108942 IPC H01J 1/30, 1991.

5. A.S. SU 1115619, IPC H01J 1/14, 9/02, 1987.

6. G.G. Bondarenko et al. “Creation of efficient cold cathodes from aluminum and beryllium”, Prospective Materials magazine, No. 2, 2007, p. 23-28.

7. RF patent 2261288, C23C 14/34, C22F 1/00, C22B 5/12, 2005.

8. S.V. Loskutov, “Changing the electron work function during elastic-plastic deformation of metals,” FIP FIP PSE Vol. 1, No. 3-4, vol. 1, No. 3-4.

9. V.M. Segal, V.I. Reznikov, V.I. Kopylov et al. “Processes of plastic structure formation of metals”, Minsk, “Science and Technology”, 1994, 232 pp.

10. N.A. Smirnova, V.I. Levit, V.I. Pilyugin et al. “Evolution of the structure of fcc crystals with large plastic deformations”, FMM, 1986, T. 61, No. 6, p. 1171-1176.

11. R.R. Mulyukov, Yu.M. Yumaguzin, “The work function of electrons from nanocrystalline tungsten,” Doklady Akademii Nauk, 2004, Volume 399, No. 6, pp. 730-732.

12. Anderson P.A. Phys. Rev. 1952. V. 88. P. 655-658.

Claims (1)

A cold metal or alloy cathode having a mixed structure containing grains and fragments of nanometric size, obtained by intensive plastic deformation, characterized in that the cathode has a mixed structure containing 50 to 95% nanometer grains, the rest of the fragments, or grain structure, containing nanometer-sized grains obtained by intensive plastic deformation and subsequent low-temperature annealing at a temperature not lower than the cathode operating temperature.