RU2510678C1 - Method of generating non-induction toroidal seeding current during steady-state operation of thermonuclear reactor - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: present invention employs a mechanism for non-inductive generation of toroidal seeding current by heating minor ions moving on potato orbits using a wideband radiation generator at an ion cyclotron frequency in the end region near the magnetic axis of the installation.

EFFECT: generating seeding current needed to design a stationary tokamak reactor.

2 cl

Description

The invention relates to the physics of high-temperature plasma and may find application in controlled thermonuclear fusion.

A known method of creating a non-induction current in closed magnetic traps of the "Tokamak" type, operating in a pulsed mode, using bootstrap current, see, for example, M. Kikuchi, M. Azumi, S. Tsuji, H. Kubo, Nuclear Fusion, 1990 , V.30, P.343.

The disadvantage of this method is that the bootstrap current density is small near the magnetic axis of the installation and grows to the periphery, which creates a nonmonotonic distribution of current density and significantly complicates the stationary operation of the reactor. In this regard, for stationary operations of the Tokamak type fusion reactor near the axis of the installation, it is necessary to somehow generate an additional so-called “seed” current (see RJBickerton, JW Connor and JB Taylor, Natural physical science 229, 110 (1971) , BBKadomtsev, VDShzfranov, in Proceedings of the 4th International Conference on Plasma Physics and Controlled nuclear Fusion Research (Vienna: IAEA, 1971) Vol.2, P.479.)

There is a known method in which, using radiation from a narrow-band ion-cyclotron frequency generator (f = f ₀ (1 ± 2%)), all particles passing in the region in which the frequency f is resonant are heated (M.Laxaback, T.Hellsten, Modeling of minority ion cyclotron current drive during the activated phase of ITER, Nucl. Fusion, v. 45, p. 1510, 2005).

The disadvantage of this method is that the frequency band of the generators currently used for plasma heating does not exceed ± 2% relative to the fundamental frequency, which leads to the fact that the current generated in this way is 0.2-0.5% of the ohmic, which is not enough to ensure stationary reactor operation.

Also known is a technical solution according to the patent of the Russian Federation No.2019874, publ. 09/15/1994, "METHOD OF SUPPORTING STATIONARY CURRENT IN PLASMA OF TOROIDAL THERMONUCLEAR INSTALLATIONS OF TYPE TOKAMAK".

The invention relates to the physics of high-temperature plasma and can be used in the development of controlled thermonuclear fusion plants. The inventive to simplify the creation and maintenance of a stationary current in a tokamak and other toroidal systems, an additional impulse is transmitted from the electrons of the beam penetrating the center of the plasma to the plasma electrons. This is achieved by the interaction of two or more counterpropagating electron beams that repeatedly go around the torus. Plasma sources are located near the chamber wall, and electrons are injected along the magnetic field. The location of the plasma sources and its parameters are selected from the condition I1> I2> Ip / n, where Ip is the plasma current; n is the number of passes of the beams around the torus; I1, I2 - beam currents. In addition, it is necessary that the energy of the particle beams be greater than the thermal energy of the plasma.

A disadvantage of the known solution is that the use of the interaction of two or more counterpropagating electron beams bypassing the torus complicates the implementation and increases the cost of a stationary fusion reactor.

In the present invention, the fact is used that potato orbits intersect the equatorial plane at any point on the equatorial plane of the tokamak, and there is a region in which there are no particles with parameters corresponding to the potato orbits, but moving in the opposite direction. The cross section of this region for the ITER installation corresponds to a circle with a radius equal to r = 0.11a, where 2a is the total size of the plasma cord in the equatorial plane. Heating of ions in all potato orbits inside the mentioned region creates a longitudinal seed current.

Since effective plasma heating in a magnetic field using radiation at the ion cyclotron frequency occurs only by heating ions that differ in mass from the ions of the main plasma, and the content of such ions in the setup does not exceed 1-10%, such ions are called small ions additives. The closest technical solution is the prototype (has the signs: A method for generating a non-induction toroidal seed current during stationary operation of a thermonuclear reactor, which includes introducing into the plasma radiation at an ion-cyclotron frequency and high-frequency heating of ions moving along the orbits passing near the magnetic axis of the tokamak) is a method non-induction current generation during stationary operation of a self-sustaining fusion reactor proposed by LG. Ericsson and F. Porcelly, Dynamics of energetic ion orbits in magnetical ly confined plasmas, Plasma physics and controlled fusion, v. 43, p. R145, 2001. To implement this proposal, we consider the heating of ions in a potato orbit passing through a magnetic axis, in which the longitudinal velocity vanishes on the axis (under the term: “ potato orbit ”should be understood as the particle’s trajectory in which the direction of the longitudinal velocity of the particle coincides with the direction of the ohmic current in the tokamak“ ... potato bootstrap current ... ”), - see for example: KCShaing et al., Steady State Tokamak Equilibria Without External Current Drive Phys. Rev. Letters, 79, 3652, 1997.

In this method, to create a stationary thermonuclear reactor based on the Tokamak system, it was proposed to use high-frequency heating of only ions moving along the orbits passing through the magnetic axis of the tokamak. In this case, a trap with a stationary toroidal magnetic field is created, it is filled with plasma with the density and temperature necessary for the implementation of self-sustaining thermonuclear reactions, and a diamagnetic current of ions is generated that pass only through the magnetic axis, using radiation from a narrow-band ion cyclotron frequency generator. The disadvantage of this method is that the diamagnetic current was calculated only on the magnetic axis of the installation, where the bootstrap current density is close to zero, and when moving away from the installation axis, the bootstrap current density increases. Such a strongly nonmonotonic current density distribution makes stable plasma confinement impossible.

The technical result of the proposed invention is the use of a seed current generation mechanism in the considered region with an increase in the transverse energy of small additive particles (for example ³ He) moving along these orbits with the help of radiation from a broadband ion cyclotron frequency generator, which allows a significant increase in the non-inductive longitudinal current compared to the current obtained by known methods, in particular, in comparison with the prototype.

вблизи магнитной оси установки, где: A=R/a - аспектное отношение, $$\varsigma =\frac{2q{\rho }_i}{R}$$

ρ_i - ларморовский радиус иона, q - коэффициент запаса устойчивости, R и а - большой и малый радиусы токамака,To achieve the indicated technical result, a method for generating a non-induction toroidal seed current during stationary operation of a thermonuclear reactor is proposed, which includes introducing radiation at the ion-cyclotron frequency into the vacuum chamber formed in the reactor chamber and high-frequency heating of ions moving along the orbits passing near the magnetic axis of the tokamak, and additionally introduced into the plasma ions ³ He, which produce high-frequency heating by wideband (Δf = ± 0.04f ₀₎ radiation generator onnoy cyclotron frequency, wherein the heating is carried out in an area with a radius of $$r=\frac{3}{2^{\raisebox{1ex}{$5$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}}Aa{\varsigma }^{\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}$$

near the magnetic axis of the installation, where: A = R / a - aspect ratio, $$\varsigma =\frac{2q{\rho }_i}{R}$$

ρ _i is the Larmor radius of the ion, q is the stability margin, R and a are the large and small radii of the tokamak,

wherein

- when forming a plasma, the vacuum chamber of the reactor is filled with a mixture of deuterium, tritium, and ³ He ions are added in an amount of 1 to 5% relative to the number of ions of the main plasma.

To achieve a technical result in the method of generating a non-induction toroidal seed current during stationary operation of a thermonuclear reactor, create a trap with a stationary toroidal magnetic field, fill it with plasma with the density and temperature necessary for the implementation of self-sustaining thermonuclear reactions, add small additive ions to it (in deuterium-tritium in plasma it can be ³ He ions), they increase the transverse energy of ions of a small additive by means of radiation from a broadband ion generator no-cyclotron frequency.

In the method for generating a toroidal seed current during stationary operation of a self-sustaining fusion reactor, the following sequence of operations is carried out.

The vacuum chamber of the Tokamak-type fusion reactor is filled with a mixture of deuterium and tritium with a small amount of ³ He (about 1-5%). A toroidal magnetic field is created inside the chamber and a vortex electric field is excited, gas is sampled, an ohmic (induction) current is excited, as a result of which the setup chamber is filled with plasma. The magnitude of the vortex electric field is controlled, the magnitude of the deuterium-tritium mixture entering the chamber from the auxiliary device, and using the system of additional heating of ions and electrons, the plasma operating parameters are reached. At the same time, the transverse energy of the additive ions is increased by the radiation of a broadband ion-cyclotron frequency generator, which leads to the generation of a toroidal seed current in the final region near the magnetic axis of the setup. The magnitude of this current is determined by the magnitude of the stability margin near the axis of the installation, the magnitude of the region in which the heating is performed, the type and number of ions of a small additive.

The proposed method for generating a toroidal seed current near the magnetic axis of the thermonuclear reactor during stationary operation of the thermonuclear reactor uses an increase in the transverse energy of the potato particles due to the use of radiation from a broadband ion-cyclotron frequency generator crossing the equatorial plane of the setup in a region in which there are no particles moving in the opposite direction (term: “potato particles” means particles (ions) moving in a “potato orbit”).

In practice, the implementation of the proposed solution is illustrated by the following operating parameters and the ratios of the used controlled quantities.

Namely: in the proposed method for generating a non-induction toroidal seed current and a poloidal magnetic field in a tokamak to provide stationary operation of a thermonuclear reactor, a non-induction toroidal seed current is additionally generated using particles moving along the orbits in the final region near the magnetic axis. The parameters for this area are defined below.

For evaluation, we use the following ITER installation parameters:

Large installation radius R = 6.2 m Small installation radius a = 2 m The magnetic field strength on the axis setting B ₀ = 5.3 T Axial safety factor q = 1 Ion density ³ He n _He = 10 ¹⁹ m ^-3 Transverse energy of accelerated ions ³ He 1 MeV Ohmic current 15 MA

The radius of the region in which it is necessary to heat the ions

$$r=\frac{3}{2^{\raisebox{1ex}{$5$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}}Aa{\varsigma }^{\raisebox{1ex}{$2$}\!\left/ \!\raisebox{-1ex}{$3$}\right.}\left(\mathrm{one}\right)$$

ρ_i - ларморовский радиус иона.where A = R / a is an aspect ratio, $$\varsigma =\frac{2q{\rho }_i}{R}$$

ρ _i is the Larmor radius of the ion.

For ITER, r / a = 0.114. Ion cyclotron lasing frequency bandwidth

$$f=f_0\left(\mathrm{one}\pm \epsilon \right)=f_0\left(\mathrm{one}\pm 0.04\right)\left(2\right)$$

.Where $$\epsilon =\frac{r}{R}$$

.

Calculations show that the proposed method allows the creation of a non-inductive toroidal seed current of 1 MA near the axis of the ITER installation, i.e. current, the maximum value of which is 6.7% of the value of the ohmic current, which is more than 10 times the magnitude of the non-induction current created in a known manner.

Claims (2)

1. A method of generating a non-induction toroidal seed current during stationary operation of a thermonuclear reactor, which includes introducing radiation at the ion-cyclotron frequency into the vacuum chamber formed in the reactor chamber and high-frequency heating of ions moving along the orbits passing near the magnetic axis of the tokamak, characterized in that it additionally ions are introduced into the plasma³He, whose high-frequency heating is produced by means of broadband (Δf = ± 0.04f₀) radiation of the ion cyclotron frequency generator, and heating is carried out in a region with a radius of

near the magnetic axis of the installation, where: A = R / a - aspect ratio,

 ρ_i - Larmor radius of the ion, q - safety factor, R and a - large and small radii of the tokamak. 2. The method according to claim 1, characterized in that when the plasma is formed, the vacuum chamber of the reactor is filled with a mixture of deuterium, tritium, and ³ He ions are added in an amount of from 1 to 5% relative to the number of ions of the main plasma.