RU2586993C1 - Centrifugal z-pinch - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention can be used as pulsed neutron and x-ray radiation source. Device consists of pulse power supply and gas-discharge chamber with electrodes and hydrogen isotopes. Electrodes are made in form of coaxial located one in another conducting bodies of revolution with curvilinear form. Around inner electrode-anode current lead there is an insulator with diameter smaller than that of working part of anode and cylindrical surface between electrodes ends in chamber. Cathode-chamber housing current lead is located near its central hole, through which insulator and anode current lead are passed. For cathode and anode additional current leads and insulator are made in mirror symmetry near cathode central hole respectively. Two anode current leads are tubular with mirror symmetric multithread spirals from inclined slots filled with solid insulators. Spirals are arranged vertically in zones of opposite corresponding gaps between electrodes ends in chamber.

EFFECT: technical result is increase of thermonuclear efficiency.

1 cl, 1 dwg

Description

The described invention relates to a plasma technique, in particular to devices with a Z-pinch configuration, and can be used as a pulsed source of neutrons and x-rays.

Known pulse source of x-ray radiation: patent RU No. 2315449 C1, 06/13/2006, Selemir Viktor Dmitrievich, Repin Pavel Borisovich, Orlov Andrei Petrovich, Pikulin Igor Valentinovich “Device for producing dense high-temperature plasma in a Z-pinch, cl. IPC H05H 1/06, publ. in BI No. 2, 2008, patent holder - Russian Federation represented by the Federal Atomic Energy Agency (RU), Federal State Unitary Enterprise “Russian Federal Nuclear Center - All-Russian Scientific Research Institute of Experimental Physics” FSUE RFNC-VNIIEF (RU ) (city of Sarov). The device contains a switching power supply, a vacuum working chamber with two electrodes. The electrodes are mounted on the same axis at a distance from each other. Between them is an axisymmetric liner cascade containing a system of electrically conductive elements with a twist angle φ ₁ relative to the axis of the cascade. At another diameter between the electrodes, at least one more liner cascade is arranged coaxially, containing a system of electrically conductive elements with an opposite twist angle φ ₂ . The electrically conductive elements are made rectilinear or spiral-shaped from wires, foil, in the form of a metal layer sprayed onto a substrate, or from a combination thereof. The twist angle of the electrically conductive elements in one cascade is chosen equal to 0 <φ ₁ ≤60 °, and in the other cascade - 60 ° ≤φ ₂ <0 °. The described analog device works as follows. When applying electric voltage from a switching power supply to a two-stage liner load, the current begins to increase through multi-wire cascades twisted in opposite directions. In this configuration, the magnetic field of the current acquires, in addition to the azimuthal component, an axial component, which is mainly concentrated in the annular region between the cascades. With a subsequent increase in current, the electrically conductive elements of the liner evaporate to form a two-layer plasma liner. The magnitude of the discharge current reaches megaampere values - in the specific case, about 20 MA. Subsequently, the current increasing along the two-layer liner system leads to its acceleration in the radial direction to the central axis of the camera. If, for example, the system is formed of spiral wires, then the plasma liner flies in the center of the chamber in the form of a compact two-layer cylinder. After the current is interrupted, the plasma cylinder collapses by inertia with the transition of the plasma thermal energy into an x-ray pulse. The configuration of this cylindrical two-layer Z-pinch, on the one hand, leads to the appearance of a “shear” of a magnetic field in the plasma liner (that is, the resulting magnetic field lines have a twist angle that varies along the thickness of the liner system) and an azimuthal rotational moment is acquired. The presence of a “shear” of the magnetic field and the torque of the plasma helps to suppress the development of destructive magnetohydrodynamic (MHD) instabilities. These factors make it possible to realize high degrees of stable radial compression of the Z-pinch in the described analogue while maintaining the initial axial symmetry (two-layer plasma cylinder at the beginning of the pinch and at the end). On the other hand, the presence of a distinctive feature — the absence of an axial magnetic field covered by the internal cascade, which counteracts the radial implosion process of a multistage cylindrical Z-pinch — causes an experimentally confirmed fact that the efficiency (efficiency) of the x-ray source increases.

The set of features of the first analogue, similar to the set of essential features of the claimed device:

1) a pulse source of electrical power;

2) a discharge chamber with two electrodes;

3) two multi-start spirals installed in height in the gap between the ends of the electrodes in the chamber.

The reasons that impede the obtaining of the required technical result from the claimed invention is the increase in thermonuclear efficiency, when implementing the first analogue, the following:

1. Two oppositely twisted multi-start spirals are made of wires exploding in the discharge chamber.

Correspondingly, the creation of a “shear” of the magnetic field and azimuthal torque of the plasma leads to filling the analog discharge chamber with ions from electrically conductive refractory materials with a large atomic number Z (tungsten, for example). In this case, the introduction of gaseous hydrogen isotopes into the chamber between the electrodes for the implementation of thermonuclear reactions during a Z-pinch discharge becomes meaningless, since the plasma from the evaporated helices will act as impurities that suppress the increase in the temperature of the thermonuclear plasma.

2. Coaxial arrangement of two oppositely twisted multi-start spirals and one discharge gap between the electrodes.

The use of two oppositely twisted current spirals creates a two-layer current-plasma shell at the beginning of the pinch. On the other hand, due to one discharge gap between the electrodes, the current-plasma shell of the analog before cumulation is the surface of one plasma volume - the same cylinder as in the classical Z-pinch, only rotating and with a circular cavity in the center. In this case, there is a technical contradiction - rotation from the “shear” and the torque of the entire plasma contribute to the radial compression of the plasma due to the suppression of MHD instabilities and at the same time prevents compression due to the appearance of centrifugal force and the selection of energy to create a twist. To increase the efficiency of the setup, it is necessary that the rotation of the plasma be used not only to create a shear and torque - by quenching the MHD instabilities, but also directly to compress the plasma.

Also known pulsed neutron source: A. with. No. 1448993, V.M. Bystritsky, M.M. Fix and V.G. Tolmacheva "Pulse source of neutrons", cl. IPC H05H 5/00, publ. in BI No. 32, 1992. The source with the end swirl of the plasma shell in the azimuthal direction contains a sealed housing in which two coaxially located cylindrical electrodes are placed coaxially, galvanically isolated from one another, a pulsed current source connected through a switch to a central electrode - anode, and a pulsed inlet system of deuterium gas or plasma. An external cylindrical electrode - the cathode is mounted at one end on the end wall of the casing and galvanically connected to a common bus. The final section of at least one of the cylindrical electrodes is made in the form of a multi-start spiral, while the angle of the spiral α, rad, the length of the spiral segment is 1 _sp , m, and the diameter of the spiral d, m is selected from the condition: 2d≥1 _sp ≥5 10 ⁴ · d · I ^-1 · tgα, where I is the current of the pulsed current source, A. A source variant is possible, in which the final section of the second electrode is also made as a multi-start spiral, the length of which corresponds to the length of the spiral section of the first electrode, and the angle of approach equal in magnitude and opposite in sign angle and the first spiral.

The device operates on the second analogue as follows. At the initial time, the current source is charged. The switch is open, the entire device is evacuated to a working vacuum, the valve of the pulsed inlet system of deuterium gas or plasma is closed. At the required time, this valve is triggered and a calculated portion of deuterium gas (or plasma) is injected into the region between the anode and cathode. After the calculated and controlled delay time, determined by the rate of filling with gas (plasma) of one annular gap between the anode and cathode, the switch is triggered and a high voltage is applied to the anode. A current begins to flow through the anode, creating an azimuthal magnetic field around the anode. As a result of the electrodynamic interaction of this field with the plasma current, determined by the Lorentz force, the current-plasma shell will begin to move to the end of the device, capturing (raking) gas in its path in this process and ionizing it as a result. Upon receipt at the end portion, where the cathode (either the anode, or both) is made in the form of a multiple start spiral, the reverse current flowing down the spiral creates an azimuthal component of the magnetic field. As a result, the current-plasma shell acquires the initial azimuthal moment of motion, and the end swirl is preserved when the plasma is carried out beyond the ends of the electrodes. After the plasma is carried out beyond the ends of the electrodes, a relatively stable plasma vortex is formed.

Due to obtaining a more stable plasma configuration — a non-cylindrical vortex, the thermonuclear efficiency of the analog installation increases in the second analogue compared to the classical cylindrical Z-pinch.

The stability of a non-cylindrical vortex is due to the following. The vortex itself has the form of a kind of torus. From below, this torus is bounded by an annular, plasma-convex current-plasma sheath, which previously acted as a magnetic piston. From above, the plasma torus is also limited by the second, but concave to the retained plasma, second current-plasma shell. The second current-plasma shell appeared as a result of lynching of the emitted plasma in a high-current discharge (the characteristic value of the discharge current corresponds to megaampere values) with the formation of a single dense rotating vortex. Between themselves, two curved surfaces of the vortex plasma torus are geometrically supplemented by two annular surfaces. The larger ring corresponds to the contact of the vortex with the cathode. The smaller ring corresponds to the contact of the vortex at the center of the anode. The presence of a torque in a plasma pinch vortex contributes to the suppression of MHD instabilities of a compressible and confined plasma, similarly to the case of the first analogue.

Analysis of current in a plasma with a helical magnetic field (p. 225-226; Artsimovich LA, Sagdeev RZ Plasma physics for physicists. - M.: Atomizdat, 1979. - 320 p.) Indicates that the current in the system is not concentrated by the idealized geometry of the pinch on the surface of the plasma bunch, but is distributed in some way over the surface section of the plasmoid. In this case, the axial and azimuthal components of the helical field coexist inside the plasma. Due to the fact that the pitch of each magnetic surface in a plasma is different, the current tubes “get mixed up” at a radial displacement (the so-called width) and a stabilizing quasi-elastic tensile force arises.

As can be seen from the analysis described, in the second analogue, a shear also develops on two current-plasma shells of a plasma vortex with its contribution, like the first analogue, to the stabilization of compression and confinement of plasma.

The set of features of the first analogue, similar to the set of essential features of the claimed device, is as follows:

1) a pulse source of electrical power;

2) a gas discharge chamber filled with hydrogen isotopes and containing gas discharge electrodes;

3) gas-discharge electrodes are made in the form of coaxial electrically conductive bodies of revolution located in one another;

4) an external electrode-cathode, an internal electrode-anode;

5) the presence of two oppositely twisted non-destructible during the discharge of multiple-start electrically conductive spirals.

The reasons that hinder the increase of thermonuclear efficiency during the operation of the device, the second analogue, are as follows.

1. As in the first analogue, in the second analogue the centrifugal forces from the rotational motion of the plasma are not used to compress the plasma, but prevent pinching. True, the selection of energy for plasma swirling, in contrast to the first analogue, is compensated by the mutual attraction of unidirectional currents on the side surfaces of the vortex separated by electrode pads. In the first analogue, the axial components of the currents responsible for the swirling of the plasma on the lateral surfaces of the cylinder have opposite directions - like a kind of multi-pass solenoid - and therefore do not add up like currents in a pinch.

2. The absence of a magnetic well - the upper current-plasma shell of a plasma vortex, convex from the side of the plasma.

As is well known (p. 218-219; Artsimovich L.A., Sagdeev R.Z. Plasma physics for physicists. - M .: Atomizdat, 1979. - 320 p.) - for closed magnetic traps the following theorem holds. It is impossible to create such a magnetic field, the intensity of which increases outward from the plasma boundary near each point on the surface of the toroidal plasma configuration. Due to its diamagnetism, the plasma itself tends to propagate towards a weaker magnetic field. Therefore, if the plasma surface is held by a magnetic field, the intensity of which decreases from the plasma boundary to the outside, then the position of the plasmoid boundary can be unstable. At the same time, for systems with low-pressure plasma (for example, a tokamak), this position is not critical.

According to the Lawson criterion, pinch systems cannot, in principle, be created with a low pressure of a thermonuclear plasma.

Due to the instability of magnetic confinement discussed above, part of the plasma will decrease from the plasma torus and the compression process will fail. It turns out that the idea of pinching only 100% of the volume of thermonuclear plasma to obtain the maximum working parameters (temperature and density) in the rotating non-cylindrical Z-pinch according to the second analogue is not realized in the entire plasma volume.

3. The technical impracticability of the plasma focusing option with a single coaxial gas-discharge gap.

Since the magnetic trap in the second analogue is not ideal, it is possible, as an option, to apply the well-known inventive technique - to turn harm in favor. That is, to use purposefully the ejection of a part of the plasma during the collapse of an open current-plasma shell, for example, for focusing the plasma. However, in the analogue under consideration, with one coaxial gas-discharge gap, it is possible to create only one whole plasma vortex. In this case, with one rotating plasma bunch when trying to organize focusing, a technical contradiction arises - the technical impracticability of two opposing movements - centripetal and centrifugal. So that focusing occurs in the analog device, the current-plasma cladding of the clot must first collapse along the central axis of the anode. On the other hand, as a result of the formation and heating, all particles of the plasma vortex acquire a rotational motion and, accordingly, centrifugal forces arise that deflect the plasma particles from the central axis of the anode, which coincides with the axis of rotation of the plasma vortex.

4. The location of multi-helix at the ends of the electrodes.

Unlike the first analogue, in the second analogue, multiple-conductive conductive spirals to create the axial components of the magnetic field are not destroyed during the discharge. The positive point from this, in relation to a thermonuclear installation, clearly consists in the fact that impurities from spiral metals do not pollute the plasma. But unlike the first analog, plasma swirling is carried out only in the final stage of the pinch. It turns out that at the stage of heating (acceleration) of the current-plasma shell, the shear and azimuthal torque are not used to stabilize the plasma MHD instabilities.

Moreover, the problem of increasing the energy consumption for the parasitic inductance of the gas discharge chamber with increasing energy invested in the discharge is not solved. If you do not take into account the presence of spiral slots at the ends of the electrodes, pulsed inlet of the working gas or plasma through a high-speed valve and the presence of the casing instead of the cathode, the installation is similar in configuration to the Meyser type plasma focus in the second analogue. We can say that both installations fundamentally, until the final stage of the discharge work the same way - they are coaxial plasma accelerators.

There is a drawback of the Meyser type plasma focus with an electrotechnical nature, which consists in limiting the growth of the discharge current with increasing installation energy at a constant operating voltage, which ultimately leads to saturation of the neutron output (p. 5, V.Ya. Nikulin, S.N. Polukhin “On the issue of plasma focus neutron scaling. Electrotechnical approach.” Preprint of LPI No 12, Moscow 2006). So, the growth of energy at a constant voltage of charging the battery is accompanied by an increase in the number of parallel connected capacitors, which leads to a decrease in the inductance of the battery. On the other hand, an increase in the battery capacity leads to an increase in the duration of the discharge and to an inevitable increase in the length of the electrodes of the discharge chamber in order to preserve the conditions for matching the moment of arrival of the current shell to the installation axis with the maximum current. As a result, there comes a time when the amplitude of the current is already determined by the inductance of the camera, and not the capacitor bank. Moreover, a further increase in battery capacity is no longer accompanied by an increase in discharge current, due to an increase in the inductance of the camera. The discharge current is saturated and, accordingly, the neutron yield is saturated. The increase in the energy of plasma focus installations (in relation to the analogue of the claimed invention can be re-arranged - coaxial plasma accelerators) is carried out, as a rule, by increasing the capacitance of the capacitor drive at a constant voltage of charging the battery, i.e. by increasing the number of parallel capacitors. Since increasing the battery capacity leads to an increase in the duration of the discharge, in order to fulfill the condition for matching the dynamics of the current-plasma shell with the duration of the current pulse - cumulation (in relation to the analogue of the claimed invention - the formation of a plasma vortex) of the current shell on the installation axis at the maximum current is necessary increase the length of the electrodes of the discharge chamber, which inevitably leads to an increase in the inductance of the chamber. Thus, a further increase in battery capacity is no longer accompanied by an increase in discharge current. The discharge current is saturated and, accordingly, the neutron yield is saturated.

A well-known drawback is also inherent in coaxial plasma accelerators - a decrease in the amplitude of the plasma accelerating voltage due to a noticeable increase in the inductance of the working chamber during the discharge, which is also caused by the relatively long length of the rectilinear acceleration path of plasma particles along the coaxial gap (p. 373-377, Hot plasma and controlled nuclear fusion. S. Yu. Lukyanov. Monograph. Main edition of the physical and mathematical literature of the publishing house. Moscow, Nauka, 1975).

If we consider the two drawbacks discussed above from the standpoint of energy efficiency - the calculation of the thermonuclear efficiency of the installation, then the situation is that even before the moment of neutron saturation, the increase in the energy input into the plasma accelerator will be accompanied by spurious energy consumption from the switching power supply for a proportional increase in the inductance of the gas discharge chamber. There is a technical contradiction - in order to put more energy into the discharge, the plasma particles must go along a longer elongated acceleration path, but with a rectilinear acceleration section, the dimensions of the coaxial accelerator, and hence its parasitic inductance, increase.

The solution to this technical contradiction could be to impart to the particles of the plasma during acceleration in the coaxial channel a spiral motion. In contrast to the rectilinear motion of the plasma, as in the second analogue, the spiral motion would make it possible to increase the plasma acceleration path for the same length of electrodes. A similar phenomenon in the second analogue takes place at the end of the pinch - the particles in the resulting plasma vortex have paths that significantly exceed the dimensions of the electrodes over which these particles circulate and the dimensions of the toroidal vortex itself. But unlike the first analogue, the plasma swirl spirals in the second analogue do not work even briefly at the beginning of the pinch.

As a prototype for the totality of signs closest to the set of essential features of the claimed invention, a device for producing pulsed x-ray and neutron radiation is selected: No. 347006, N.G. Makeev, T.I. Filippova and N.V. Filippov “Plasma source of penetrating radiation”, cl. IPC H05H 1/06, publ. in BI No. 4, 1995. A plasma source of penetrating radiation consists of a gas discharge chamber filled with hydrogen isotopes and containing gas discharge electrodes, and a pulsed electric power source. The electrodes are made in the form of coaxial electrically conductive bodies of revolution located in one another with a curvilinear generatrix, in a particular case representing the voltage of an elliptical arc with a straight segment inclined to the camera axis. The internal electrode serving as the anode is mounted on a cylindrical input surrounded by an insulator. The input of the inner electrode has a diameter smaller than the diameter of the working part of the inner electrode. The insulator between the electrodes, made, for example, of alunda, has a cylindrical shape. On the external electrode, which is the cathode, in the immediate vicinity of the insulator, cylindrical recesses are made. They are located uniformly around a circle, the center of which is on the axis of the chamber, and serve to bind the beginning of the discharge in order to evenly distribute the current in the discharge chamber.

The prototype device works as follows. After applying voltage from a pulsed source to the anode, a cylindrical plasma shell having a fibrous structure is formed near the insulator. Under the action of electrodynamic forces, the plasma shell moves away from the insulator and moves with acceleration along the interelectrode gap to the focusing region, which is located on the axis of the discharge chamber near the anode surface from the side of the chamber opposite the insulator. The plasma focus formed during the discharge is a source of neutrons and x-rays.

The set of features of the prototype, similar to the set of essential features of the claimed device is as follows:

1) a pulse source of electrical power;

2) a gas discharge chamber filled with hydrogen isotopes and containing gas discharge electrodes;

3) the electrodes are made in the form of coaxial electrically conductive bodies of revolution located in one another with curvilinear generators;

4) the internal electrode is the anode;

5) at the same time, the cathode serves as the camera body;

6) an insulator is installed around the anode current lead, having an outer cylindrical surface with a diameter smaller than the diameter of the working part of the anode inside the chamber between the ends of the electrodes;

7) an insulator and anode current lead are passed through the central hole in the cathode;

8) the cathode current lead is placed near its central hole.

The reasons that hinder the increase of thermonuclear efficiency during the operation of the prototype are as follows.

1. The lack of technical means that change the geometric structure of the plasma focus, which prevents the improvement of plasma focus systems.

As is known, the mechanism of plasma focus formation is as follows. When cumulating the current-plasma shell (pp. 36-37, Valery Nikulin, manuscript. On the rights of the manuscript - The dissertation for the degree of Doctor of Physics and Mathematics “High-current discharge of the plasma focus type. Physical processes and applications in technology.” Physical Institute named after PN Lebedev, Moscow, 2007) on the camera axis there is a rapid compression (pinching) of the plasma near the surface of the anode to a certain minimum, for the entire time of the pinch, radius. The maximum compression is followed by a slight expansion of the pinch, and the Rayleigh – Taylor instability of the type of constrictions with a wavelength of 2–10 times less than the total length of the plasma column develops on its surface, leading to the appearance of a second plasma compression. The diameter of the plasma cylinder in the 1st compression is 0.3-1.5 cm, in the second it is 0.1-0.5 cm. Due to the outflow of a large mass of plasma during compression upwards due to the non-cylindrical shape of the shell and radial emission (due to development of pinch instabilities) a significant part of the energy is transferred to a small amount of the remaining substance. In this magnetohydrodynamic regime, the plasma is efficiently heated under compression.

The resulting zone of high-temperature plasma is an intense source of radiation and is called the plasma focus.

The resulting plasma clot — the plasma focus — is relatively small in comparison with the dimensions of the gas discharge chamber of the plasma focus units.

For example (p. - 5; 13, V. Ya. Nikulin, S. N. Polukhin “On the issue of neutron scaling of the plasma focus. Electrotechnical approach.” Preprint FIAN No 12, Moscow 2006), at the PF-3 INS RRC Kurchatov Institute The plasma column of focus has a height of about 5 cm and a maximum pinch diameter of about 1.5 cm (as mentioned above). At the same time, the diameter of the cathode (i.e., the body of the gas discharge chamber) is slightly more than one meter and is equal to 116 cm, and the diameter of the anode is one meter. True, these values are given for non-thermonuclear modes - without deuterium in the chamber.

In addition to another example, another source indicates that the characteristic focus sizes for thermonuclear plasmofocus units (p. 613, Physical Encyclopedia / Ed. By A.M. Prokhorov Ed. By D.M. Alekseev, AM Baldin, AM Bonch-Bruevich A.S. Borovik-Romanov et al. - M.: Big Russian Encyclopedia. T. 3. Magnetoplasmic - Poynting's theorem. 1992. 672 p., Ill.) Are in the range of 0.01-3 cm.

These are also relatively small values in comparison with the sizes of the electrodes - for installing the PF-400 Tulip FIAN (p. 45, Valery Nikulin, manuscript. On the rights of the manuscript - The dissertation for the degree of Doctor of Physics and Mathematics “High-current discharge like plasma focus. Physical processes and applications in technologies. ”PN Lebedev Physical Institute, Moscow, 2007) with Filippov geometry, the cathode diameter is 50 cm and the anode diameter is 40 cm, respectively.

On the one hand, in comparison with existing pinch systems, the plasma focus is characterized by the highest plasma compression efficiency (p. 613, Physical Encyclopedia / Ed. By A.M. Prokhorov. Ed. By. D.M. Alekseev, A.M. Baldin, AM Bonch-Bruevich, AS Borovik-Romanov, etc. - M .: Big Russian Encyclopedia. T. 3. Magnetoplasmic - Poynting's theorem. 1992. 672 p., Ill.) And, accordingly, a higher energy concentration in unit pinch volume. So, with plane compression, the plasma density increases by about 4 times, in a cylindrical chamber, taking into account the reflection of the shock wave, by 33 times, and in the case of focusing as a result of a partial ejection of mass on a portion of a height limited along the axis (for example, 5 cm near the installation PF-3) the density increases by 10 ³ times (taking into account the decrease in entropy).

This characteristic, the high efficiency of pinching the plasma focus, indicates the advisability of introducing focusing of the plasma vortex into gas-discharge installations according to the second analogue.

On the other hand, if we take only the plasma focus unit itself and compare the value of the energy invested in the focus with the value of all the energy received from the switching power supply - a capacitor bank, small values occur.

So developers and experimenters say (p. 109, All-Union Institute of Scientific and Technical Information. Results of Science and Technology. Plasma Physics Series. Volume 2. Editor - VD Shafranov. Moscow. 1981) about the focus energy content of about 10% of the battery energy.

Theorists, speaking of a plasma clot that occurs already during the second compression of the plasma, predict (p. 240; 243, Questions of the theory of plasma. Collection of articles. Issue 8. Edited by Academician MA Leontovich. M., Atomizdat, 1974, p. 384.) Only 3% of the energy invested in the focus of the battery energy.

Such small values of the relative energy deposition in the plasma focus can be explained by the small mass of the plasma in the focus. If a central hole is made in the cathode (p. 217-218, L. A. Artsimovich. Controlled thermonuclear reactions. State Publishing House of Physics and Mathematics. Moscow. 1961), and a plasma focus installation is used as a plasma injector (plasma gun), then As a result of the first experiments on small low-power installations, the mass of the ejected “projectile” —the plasma focus — was obtained, only a few tenths of a percent of the total mass of gas in the discharge chamber.

An increase in the energy input at subsequent plasma focusing installations did not save the situation.

Saturations are observed on megajoule range installations (pp. 166-167; 173, Valery Nikulin, Nikulin, manuscript. On the rights of the manuscript - The dissertation for the degree of Doctor of Physics and Mathematics “High-current discharge like plasma focus. Physical processes and applications in technologies”. PN Lebedev Physical Institute, Moscow, 2007) neutron and hard x-ray radiation outputs. The increase in energy input into discharge in megajoule installations is not accompanied by an increase in penetrating radiation.

In other words, for any energy industry, existing plasma focus units have a relatively small plasma focus in size and energy content.

It turns out that when working with classical plasma-focusing systems, a technical contradiction arises - on the one hand, it is necessary to provide as compact plasma focusing as possible, on the other hand, a compact linear pinch obtained by focusing results in small percentages of the focused plasma, the percentage of energy input into the focus, and impossibility growth of energy input in megajoule areas.

2. The presence of movement of the current-plasma shell from the perimeter of the anode along its upper surface to the center of focusing.

It is well known that stabilization of plasma instabilities under certain conditions can occur spontaneously as a transition to an energetically more favorable state when, due to the development of instability, the processes of particle and energy transfer are adjusted in such a way that stable current distributions are realized. Such plasma self-organization is most clearly manifested in current systems — tokamaks and pinches with a reversed magnetic field (pp. 656-658, Physical Encyclopedia / Ed. By A.M. Prokhorov. Ed. By D.M. Alekseev, A.M. Baldin, A.M. Bonch-Bruevich, A.S. Borovik-Romanov, etc. - M .: Big Russian Encyclopedia. T. 4 Poynting-Robertson-Streamers, 1994, 704 pp., Ill.).

In the study of the plasma focus with a spherical chamber, created as a special case of the prototype device, it was found that the initial phase of the motion of the plasma shell in the SFC from the insulator to the equatorial zone of the chamber obeys the laws of shell dynamics in the inverse Z-pinch (Development and study of spherical chambers with plasma focus N.G. Makeev, V.G. Rumyantsev, G.N. Cheremukhin - page of the site http://pandiaweb.ru/text/77/309/52969.php of the online publication Pandia.ru). This provides automatic adjustment of the speed of movement of various sections of the shell and improves its axial symmetry.

In the prototype device, of course, as in a plasma focus with a spherical chamber, when the current-plasma shell moves from the insulator to the perimeter of the anode ellipsoid, auto-adjustment of the speed of movement of various sections of the shell and improvement of its axial symmetry will also be observed.

Unfortunately, then the current-plasma shell begins to move toward the center of the anode surface with a decrease in its radius and, as a classical Z-pinch, becomes susceptible to plasma instability of the type of constriction.

3. The lack of technical means to create a shear and azimuthal torque of a compressible plasma.

The current-plasma shell in the plasma focus setups of the Filipov and Maser type, as is well known, has the form of a surface concave from the side of the plasma. Under the pressure of dynamic pressure, the current-plasma shell in the prototype device is also convex towards the compressible plasma. It automatically produces a kind of magnetic well, which contributes to the suppression of MHD instabilities on the surface of the magnetic piston.

However, only the concavity of the current-plasma shell is insufficient to eliminate all MHD instabilities, since the current-plasma shell in the setup, the plasma focus and the compressible plasma itself have an inhomogeneous structure with density discontinuities.

The current-plasma shell at the initial stages of the development of the plasma focus has a fibrous structure, which subsequently leads to the development of undesirable plasma instabilities (pp. 93-95, All-Union Institute of Scientific and Technical Information. Results of Science and Technology. Plasma Physics. Volume 2. Editor - V.D. Shafranov. Moscow, 1981). When a high voltage is applied to the anode, an electric field arises with a maximum at the cathode-insulator boundary. From this edge, an ionization wave begins to propagate along the surface of the insulator and reaches the anode edge. From this moment in time, the electric field is almost constant and reaches several kV / cm. The gas gap is an ohmic load in which conductivity continues to increase due to ionization of the gas (deuterium). Moreover, the presence of a small gradient of the electric field when moving away from the insulator leads to a sharp inhomogeneity of ionization - “ionization current screening” near the insulator. At this stage, the external signs of a gas discharge are manifested — the nucleation of anode spots giving rise to the azimuthal current structure (formation of current fibers), as well as the appearance of transverse striations. These strata correspond to the alternation of sections of different densities and temperatures along the current fiber. The resulting fibrous current-plasma shell under the action of the ponderomotive current begins to move to the axis of the installation and pushes the shock wave in front of it. In the process of movement, the current-plasma shell contracts, takes the form of a funnel with a neck to the anode, and the current fibers close. Moreover, the previously formed strata can initiate the development of MHD instability of the plasma column at the stage of formation of the plasma focus.

In addition to the transverse structures - striations, there are also longitudinal azimuthal structures generated by the fibrous nature of the current-plasma shell, preventing both the formation of a plasma focus and the raking of gas by the current-plasma shell to the focus axis (p. 148, 149; 161, 163, Valery Nikulin, Nikulin , manuscript. On the rights of the manuscript - The dissertation for the degree of Doctor of Physics and Mathematics "High-current discharge of the plasma focus type. Physical processes and applications in technology", PN Lebedev Physical Institute, Moscow, 2007). Firstly, these are the “triaxes”. At the stage preceding the first compression, the current has a fibrous structure, the magnetic field near the axis acquires a multipole character, and the opposite direction current can be excited on the PF axis, which, closing on itself, forms a loop. This will lead to plasma deceleration and the formation for some time (up to the absorption and dissipation of this current) of a quasi-equilibrium configuration of the Triax type with a fibrous structure. Secondly, this is the filament structure of the current-plasma membrane. The absolute yield of hard radiation from a plasma focus type installation largely depends on how efficiently the current-plasma shell rakes the working gas. Residual gas can cause secondary breakdowns near the insulator and thereby shunt the current flowing through the pinch. The reason for the formation of the second current shell is associated with the filamentation of the first current shell, as a result of which it does not completely rake the working gas. In turn, the causes of filamentation are a distortion of the uniformity of development of the uniformity of the azimuthal fibrous structure of the current-plasma shell, which is due to two reasons: the presence in the current shell of impurities from the structural materials of the discharge chamber and overheating of the shell. Impurities reduce the conductivity of the shell, increase and loosen its skin layer, which leads to the appearance of large-scale inhomogeneities. Overheating of the shell is associated with the existence of a limit restricting the transfer of battery energy per unit surface of the plasma shell and the working surface of the insulator, above which the so-called overheating instability develops.

Uncompensated by a magnetic well in the plasma focus of MHD instability could be suppressed, as in analog devices, due to the width of the current-plasma shell and the azimuthal rotational moment of a compressible plasma. However, in the installation of the prototype there are no multi-current current spirals for plasma swirling.

4. The absence of a shear will negatively affect the raking of the working gas of the newly created plasma focus installation if it contains only the movement of the current-plasma shell, as in the inverse pinch, from the center to the perimeter with an increase in the radius of the shell.

The fact is that in the prototype installation, the current fibers initially diverge from each other on the lower side of the anode - as in the reverse pinch, but then they still stick together when focusing on the upper side of the anode.

If constructive conditions are created only to expand the gap between the fibers of the sheath, then leakage of the raked working gas will be observed between the non-tangled straight fibers.

5. Axial rectilinear motion of plasma particles upon heating.

The proposed electrode system in the prototype device provides an extended phase of the accelerated movement of the plasma shell in the coaxial gap (like Maser) and a fleeting phase of its radial convergence to the camera axis (like Filippov). At the same time, the radial rectilinear motion of the current-plasma shell during an extended phase of accelerated motion (under the bottom of the anode) leads, as in coaxial plasma accelerators, to a decrease in the amplitude of the plasma-accelerating voltage due to a noticeable increment in the inductance of the working chamber during the discharge, which is caused by the relatively large length of the rectilinear path of plasma particle acceleration along the coaxial gap. Like the second analogue, the prototype also has a technical contradiction - in order to put more energy into the discharge, the plasma particles must go along a longer elongation path, but with a rectilinear acceleration section, the dimensions of the coaxial accelerator, and hence its parasitic inductance, increase.

6. The decrease in the area of the current-plasma shell when it converges to collapse.

In the transient phase of radial convergence to the camera axis, the entire current-plasma shell is on the upper surface of the anode ellipsoid. With the convergence of the current-plasma shell, its diameter decreases - accordingly, the area of the shell decreases. A decrease in area can provoke filamentation due to the risk of exceeding the limit limiting the transfer of battery energy per unit surface of the plasma shell, and, accordingly, the development of overheating instability.

7. Small contact area of the neck of the plasma funnel with the surface of the anode. Due to the small area of the neck of the plasma funnel, the metal surface of the anode evaporates, and the resulting impurities with a large atomic number Z are released into the plasma, and, as a result, the plasma temperature decreases.

The technical problem to which the invention is directed is on the one hand. radically change the geometry of the plasma bunch in the plasma focus setup and, accordingly, increase the relative values of the size, volume, and energy input of the plasma focus, and, on the other hand, compensate for the increase in energy consumption for the formation of a larger plasma focus due to:

1) suppression of MHD instabilities of the plasma by adding to the magnetic well of the plasma focus of the shear, the plasma rotational moment, and automatically adjusting the speed of movement of various sections of the current-plasma shells when they move perpendicular to the cylindrical surface of the insulators with a symmetric increase in the radius of the vortices;

2) improving raking of the working gas due to the shear on raking current-plasma shells;

3) the use of centrifugal forces from the rotation of the plasma to compress the plasma;

4) auto-adjusting the speed of movement of various sections of current-plasma shells and improving their axial symmetry;

5) reducing the parasitic inductance of the chamber and its numerical growth with pinch;

6) a noticeable increase in the area of the current-plasma shell throughout its existence;

7) utilization of the azimuthal components of the current of the current-plasma shell for the collapse of the shells;

8) growth during pinch of the contact area of the neck of the collapse of the current-plasma surfaces on the anode.

The technical result expected from the solution of the technical problem during the implementation of the claimed invention is to increase the thermonuclear efficiency of a gas-discharge installation with a modernized plasma focus.

The technical task is solved thanks to the installation with a Z-pinch, which has the following characteristic essential features that match the characteristic features of the prototype device:

1) a pulse source of electrical power;

2) a gas discharge chamber filled with hydrogen isotopes and containing gas discharge electrodes;

3) the electrodes are made in the form of coaxial electrically conductive bodies of revolution located in one another with curvilinear generators;

4) the internal electrode is the anode;

5) at the same time, the cathode serves as the camera body;

6) an insulator is installed around the anode current lead, having an outer cylindrical surface with a diameter smaller than the diameter of the working part of the anode inside the chamber between the ends of the electrodes;

7) an insulator and anode current lead are passed through the central hole in the cathode;

8) the cathode current lead is placed near its central hole, the following distinctive essential features are added:

1) an additional central hole is made at the cathode;

2) for the cathode and anode, the additional current leads and the insulator are respectively symmetrically made near this additional central hole of the cathode;

3) two current leads of the anode are made tubular with mirror-symmetric multi-start spirals from inclined slots;

4) the spirals are arranged in height in zones opposite the corresponding gaps between the ends of the electrodes in the chamber;

5) the inclined slots of the spirals are filled with solid insulators.

The combination of all the essential features of a modernized plasma focus installation eliminates the diversity of its technical applications, which serves as the key to solving the technical problem of the claimed invention. If a classical plasma focus can be used to make a hole in the center of the cathode for shots with plasma columnar clots, like shells in a plasma injector, then in a modernized pinch “shots” are made in the form of single rings along a circular perimeter around the anode. The use of an upgraded pinch in the form of a plasma gun for pumping thermonuclear magnetic traps, plasma shots in military electrodynamic guns, and plasma space rocket propulsors is specially eliminated.

In order to form a plasma focus at the end of the pinch in the form of a ring around the perimeter of the working part of the anode on the mirror symmetry axis of the cathode and anode current leads at the beginning of the pinch, two symmetric current-plasma shells are created at the center of the installation at two insulators. Further, these shells move to the perimeter of the anode, where they collide, starting from the soles, with their lateral surfaces and form a quasitoroidal pinch.

The following salient features of the new installation provide ring focus:

1) a pulse source of electrical power;

2) a gas discharge chamber filled with hydrogen isotopes and containing gas discharge electrodes;

3) the electrodes are made in the form of coaxial electrically conductive bodies of revolution located in one another with curvilinear generators;

4) the internal electrode is the anode;

5) at the same time, the cathode serves as the camera body;

6) an insulator is installed around the anode current lead, having an outer cylindrical surface with a diameter smaller than the diameter of the working part of the anode inside the chamber between the ends of the electrodes;

7) an insulator and anode current lead are passed through the central hole in the cathode;

8) the cathode current lead is placed near its central hole;

9) an additional central hole is made at the cathode;

10) for the cathode and anode, the additional current leads and the insulator are respectively symmetrically made near this additional central hole of the cathode;

11) two current leads of the anode are made tubular.

To eliminate compensation in the form of an increase in the energy input with increasing dimensions of the new ring plasma focus, measures have been introduced to suppress MHD plasma instabilities by adding a shear with a plasma torque to the system and automatically adjusting the axial velocity of the swirling current-plasma shells expanding symmetrically and perpendicularly from the cylindrical surfaces of the insulators, improving raking of the working gas due to the shear of the current-plasma shell, the use of centrifugal forces from the rotation of the plasma for compression plasma, reducing the parasitic inductance of the chamber and its numerical growth during pinch, utilization of the azimuthal components of the current of the current-plasma shell for collapse of the shells, as well as measures to reduce the increase in energy density on the surfaces of the current-plasma shells and the surface of the anode up to the moment of counter collapse of the shells due to a noticeable increase in the area of the current-plasma shell during its existence and growth during the pinch of the contact area of the collar of the collapse of the current-plasma over awns at the anode. In other words, increased energy efficiency of plasma heating for the formation of a plasma focus.

It should be noted that the process of automatic adjustment of the axial motion speed flying symmetrically and perpendicularly from the cylindrical surfaces of the insulators of non-rotating current-plasma shells occurs even when the above eleven essential characteristic features of the claimed device are realized.

All the described effects (except, of course, auto-adjustments) for increasing the energy efficiency of heating are achieved due to the vortex motion of two current-plasma shells throughout their existence, starting from the formation and development of insulators around the cylindrical surfaces and ending with a joint collision with collapse. The following significant distinguishing features of the new installation provide energy efficiency (in conjunction with the essential distinguishing features described above) - the absence of an increase in energy consumption for creating a ring focus:

1) two tubular current leads of the anode are made with mirror-symmetric multi-start spirals from inclined slots;

2) the spirals are arranged in height in zones opposite the corresponding gaps between the ends of the electrodes in the chamber.

To prevent secondary parasitic discharges around the spirals of the tubular current leads of the anodes, the following significant feature has been added to the upgraded plasma focus installation.

1. The inclined slots of the spirals are filled with solid insulators.

The technical solution allows two created current-plasma shells to move along parallel annular coaxial channels in the form of expanding two mirror-symmetric vortices and accelerate both under the action of ponderomotive current forces and centrifugal forces. Due to the fact that rotating current-plasma shells have a shear, and compressible plasma, which is formed by a shock wave from the radial motion of current-plasma shells, has an azimuthal rotational moment, conditions are created for suppressing MHD plasma instabilities. In addition, the damping of MHD instabilities of current-plasma shells in the claimed device is facilitated by the automatic adjustment of the axial motion speed of their boundaries, which occurs during symmetrical expansion perpendicular to the cylindrical surfaces of the insulators of the vortices of these shells. Due to the confusion of the fibers, raking of the working gas is improved at wider during auto-regulated expansion of current-plasma shells. Since the particles in the current-plasma shells have a swirling motion in the coaxial accelerating gaps, it becomes possible not to increase the size of the installation and, accordingly, the loss of the initial parasitic inductance of the working chamber and the growth of this inductance during discharge. It is characteristic that the area of two current-plasma shells increases, since their diameter increases during acceleration. Therefore, the conditions for the development of overheating instability will not come. On the perimeter of one common for two current-plasma shells of the anode, the front edges of the two lateral surfaces of the shells collide, they collapse together and the formation of an annular plasma focus. As a result of the addition of the unidirectional azimuthal current components responsible for the rotation of the plasma in the vortices, the collapse increases the pulsed magnetic field to focus the pinch and thus compensates for the decrease in the translational velocity of the plasma during its vortex motion in the annular coaxial gaps of the modernized installation. Due to the fact that the neck of the funnel from two lateral surfaces of the opposing current-plasma shells lies on the annular surface around the entire perimeter of the anode, and not in a small spot spot in the center of the anode, as in a classical plasma focus installation, the evaporation of the anode metal during plasma cumulation is reduced to a minimum.

Summarizing the foregoing, as a result, we have an increase in the relative sizes, volume, and enclosed energy of the plasma focus without a relative increase in energy consumption for the formation of a new plasma structure, and hence, an increase in neutron and x-ray radiation at a given energy.

Thermonuclear efficiency is increasing - a technical result has been achieved.

The technical nature of the proposed technical solution is illustrated by the drawing - Fig. 1, which depicts the following elements:

1) cathode;

2) the working part of the anode;

3) a cylindrical insulator between the electrodes;

4) a tubular current lead of the anode;

5) an open conductive coil of a multiple start spiral;

6) an insulator of adjacent turns of a multi-start spiral;

7) cathode current lead;

8) arrester;

9) low inductance high voltage capacitor bank;

10) quasitoroidal plasma focus.

ω ₁ = ω ₂ - respectively equal in magnitude and direction of the angular velocity of rotation of two mirror plasma vortices.

Dashed lines show the cross sections and positions of the current-plasma shells as they move from the corresponding cylindrical surface of the insulator to the perimeter of the anode.

The cathode material is stainless steel. The cathode consists of two mirror halves, which are connected together vacuum-tight (not shown in the drawing).

The material of the anode is electrical copper.

The working surfaces of the electrodes are outlined using ellipsoids of revolution.

It is proposed to use brokerite as the material of the insulator between the electrode (pp. 134-137, Balkevich VL Technical ceramics: Textbook. Manual for technical colleges. - 2nd ed., Revised and additional - M .: Stroyizdat, 1984. - 256 p., Ill.). At normal temperature, the thermal conductivity of electrically insulating ceramics based on beryllium oxide exceeds the thermal conductivity of other oxide and ceramic materials by 7-10 times. Under normal conditions, the thermal conductivity of beryllium oxide also exceeds the thermal conductivity of a number of metals (steel, nickel, molybdenum, lead, etc.). True, with increasing temperature, the thermal conductivity of beryllium oxide, like that of other oxide ceramics, drops sharply, but in the high temperature region (1500-1800 ° C) the thermal conductivity of BeO is 1.5-2 times higher than the thermal conductivity of other oxide ceramics. The volatility of sintered beryllium oxide ceramics in vacuum is practically not detected up to 2000-2100 ° C.

At one time, when the installation — the plasma focus — began to be created, it was proposed to replace the lateral dielectric surface of the installation of a classical Z-pinch with a copper one. Due to the better thermal conductivity of copper compared to the insulator, it was assumed and obtained a decrease in impurities in the pinch plasma.

In the inventive installation, the contact of the plasma with the insulator could not be completely eliminated. Therefore, by analogy, it is proposed to increase the thermal conductivity of one of the surface of the gas discharge chamber. Only not by replacing the dielectric with a conductor, but by increasing the thermal conductivity of the insulators between the electrodes when using beryllium oxide. The radiation resistance of beryllium oxide allows such a replacement - beryllium oxide, as is well known, is a good matrix material for nuclear fuel.

As materials for insulators filling the spiral slots on the tubular current leads of the anodes, mica can be used. The flexibility of the mica makes it easy to fill the curved grooves of the slots. Not the last argument in favor of the use of mica in the inventive device is the high radiation resistance of mica materials.

However, fluoroplastic can also be used as materials for insulators filling spiral slots on the tubular current leads of anodes. It is not necessary to achieve vacuum tightness on the spirals of the current leads. Therefore, unlike solid ceramic insulators between the electrodes, flexible dielectrics can be used for laying in spirals, which is technologically simpler.

The claimed device operates as follows.

After applying voltage from a pulsed source through a spark gap to the anode, two cylindrical plasma shells having a fibrous structure are formed near two insulators. Under the influence of electrodynamic forces, the plasma shells symmetrically move away from the insulators. Due to the pulsed current in the multi-helix spirals of the two current leads of the anode, the shells acquire an additional motion — rotational azimuthal — to the already existing axial one. Due to this rotation, the fibers of the current-plasma shells are mixed to form a shear. Two vortices are unwound in two parallel annular coaxial gaps between the electrodes. The diameters of the vortices increase all the time. The plasma formed from two shock waves in front of the shells acquires a rotational moment. After a certain time, the current-plasma rotating shells under the action of ponderomotive and centrifugal forces go out with their soles to the perimeter of the anode. Here they collide with their side surfaces. The geometry of the chamber and the inductance of the capacitor bank are selected so that the maximum current pulse coincides in time with the moment the surfaces of the shells meet. Next, the formed wedge-shaped annular channel collapses due to the fusion of the spiral currents of the shells with the eddy flowing of part of the plasma to the side to the inner perimeter of the cathode. Vortex flow leads to cumulation of plasma. The pinching of the resulting pinch, by analogy with the plasma focus, will be accompanied by the transfer of energy to a part of the plasma — to the resulting compact plasma clot — a quasitor in the inventive device. This focused plasma quasitor is a source of neutrons and x-rays.

The inventive device is a type of non-cylindrical Z-pinch, which paradoxically uses centrifugal forces and effects.

For this reason, the inventor called the claimed pinch installation - "centrifugal Z-pinch."

Claims (1)

A plasma source of penetrating radiation, consisting of a pulsed electric power source and a gas discharge chamber filled with hydrogen isotopes and containing gas discharge electrodes made in the form of coaxial electrically conductive rotation bodies with curvilinear components arranged one inside the other, an insulator is installed around the current lead of the internal electrode - anode, having an inside of the chamber between the ends of the electrodes the outer cylindrical surface with a diameter smaller than the diameter of the working part of the anode, the current lead of the cathode - the camera housing is placed near its central hole, through which an insulator and anode current lead are passed, characterized in that for the cathode and anode additional current leads and an insulator are made mirror-like respectively near the additional central cathode hole, moreover, two anode current leads are made tubular with mirror-symmetric multi-paths spirals from inclined slots filled with solid insulators, while the spirals are located in height in areas opposite the corresponding gaps between the end faces mi electrodes in the chamber.

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