CN220232739U - Plasma window structure for relieving heat load of divertor in magnetic confinement fusion device - Google Patents

Abstract

The utility model discloses a plasma window structure for relieving the heat load of a divertor in a magnetic confinement fusion device, which comprises a main vacuum chamber and a divertor chamber, wherein the divertor chamber is provided with a divertor target plate, the throat width of the divertor chamber is narrowed, a long and narrow area is constructed between the throat narrowed position of the divertor chamber and the main vacuum chamber to form a plasma window, and the divertor chamber is provided with an air charging hole for charging neutral gas into the area where the divertor target plate is positioned to form a high-pressure end of the plasma window. The structure can increase the neutral air pressure near the target plate of the divertor while maintaining the neutral air pressure required by the main vacuum chamber, so as to form a high-pressure air target, block the particle flow and the heat flow from the upstream and effectively relieve the high heat load of the target plate.

Description

Plasma window structure for relieving heat load of divertor in magnetic confinement fusion device

Technical Field

The utility model relates to the technical field of magnetic confinement fusion and windowless sealing, in particular to a plasma window structure for relieving the heat load of a divertor in a magnetic confinement fusion device.

Background

Divertors are an important component of magnetically confined fusion devices. The primary function of the divertor is to expel the particle and heat flows from the core while shielding impurities from the walls of the device, reducing contamination of the core plasma by impurities. The problem of divertor thermal loading is faced with a significant challenge, and particle flow and heat flow from the tokamak core can be transported along the SOL to the divertor target plate. According to the estimation, taking the ITER device as an example, if a common non-optimized divertor is adopted, the steady-state heat flow reaching the divertor target plate may exceed 100The transient heat flow may be an order of magnitude higher. The most advanced ITER-like tungsten copper water-cooled divertors can bear about 15 ± heat load>. The two have a gap of 1-2 orders of magnitude, and the problem of controlling the heat flow of the target plate of the divertor has become a blocking tiger for the future long-pulse steady-state operation fusion reactor. At present, the divertor enters an off-target running state by filling extra neutral gas near the target plate, so that the heat load of the target plate can be effectively relieved. However, since the divertor chamber is in communication with the main vacuum chamber, deuterium gas is introducedThe normal discharge of the main plasma is likely to be affected, and if inert gas is injected, the main plasma may be polluted, so that the confining performance of the core plasma is seriously affected, and even the core plasma is broken.

The present utility model has been made in view of this.

Disclosure of Invention

The present utility model aims to address the above-mentioned problems in the prior art by providing a plasma window structure for alleviating the thermal load of a divertor in a magnetically confined fusion device.

The plasma window is a windowless sealing means for realizing a high vacuum chamber and a low vacuum chamber by utilizing a section of thermal plasma. Since the plasma window has a characteristic of allowing high-temperature charged particles to pass therethrough while blocking low-temperature neutral particles from passing therethrough, if it can be applied to a magnetic confinement fusion device to separate a main vacuum chamber and a target plate region of a divertor, it is possible to prevent neutral gas and high-Z impurities from entering the main plasma while increasing the pressure of the divertor, reducing the thermal load of the target plate.

Therefore, a scheme is developed to separate the main vacuum chamber and the divertor chamber of the magnetic confinement fusion device by using a plasma window, and prevent neutral gas from entering the upstream of the main vacuum chamber, so that more gas can be filled in the divertor region to form a high-pressure gas target, thereby fundamentally solving the problem of heat load of the divertor. Based on the above, the technical scheme of the utility model is as follows:

a plasma window structure for relieving the thermal load of a divertor in a magnetically confined fusion device comprises a main vacuum chamber and a divertor chamber, wherein the divertor chamber is provided with a divertor target plate, the throat width of the divertor chamber is narrowed, a long and narrow region is constructed between the narrowed position of the throat of the divertor chamber and the main vacuum chamber to form a plasma window, and the divertor chamber is provided with an air charging hole for charging neutral gas into the region where the divertor target plate is positioned to form a high-pressure end of the plasma window.

When the plasma window structure is used, the area where the divertor target plate is located is a high-pressure end, and the main vacuum chamber area is a low-pressure end, so that neutral gas enters the plasma window from the area where the divertor target plate is located and then enters the main vacuum chamber area, most of the neutral gas entering the plasma window area can be ionized by heat flow from the scraping layer of the main vacuum chamber, low-temperature high-density plasmas with several electron volts are formed, and the structure has the characteristics of allowing high-temperature charged particles to pass and blocking low-temperature neutral particles to pass, namely, the plasma window is formed, and the effect of blocking the neutral gas is achieved.

Alternatively or preferably, in the above plasma window structure, an exhaust port is provided at a junction between the plasma window and the main vacuum chamber to prevent the unionized neutral gas from the high-pressure end from entering the upstream of the main vacuum chamber.

Compared with the prior art, the utility model has the following beneficial effects:

according to the utility model, by shrinking the throat width of the divertor chamber and increasing the long and narrow area at the junction of the throat of the divertor chamber and the main vacuum chamber to form a plasma window, the characteristic that the plasma window can allow high-temperature charged particles to pass through to block low-temperature neutral particles from passing through is utilized, the neutral air pressure near the divertor target plate in the divertor chamber is increased while the neutral air pressure required by the main vacuum chamber of the magnetic confinement fusion device is maintained, a high-pressure air target is formed, the particle flow and the heat flow from upstream main plasma are blocked, and the high heat load of the divertor target plate is relieved.

In addition, an extraction opening is added at the junction of the plasma window and the main vacuum chamber, so that the residual neutral gas which is not ionized and comes from the high-pressure end is prevented from entering the upstream of the main vacuum chamber.

The structure of the utility model can be directly modified on the basis of the existing tokamak, and has low modification cost, simple structure and obvious effect of relieving the heat load of the divertor.

Drawings

FIG. 1 is a schematic diagram of the plasma window structure for relieving the thermal load of a divertor in a magnetically confined fusion device according to the present utility model;

FIG. 2 is a schematic diagram showing the cross-sectional structure of the primary vacuum chamber and the divertor chamber of the HL-2A device;

FIG. 3 is a schematic diagram of a design of a plasma window structure for mitigating thermal loading of a divertor in a magnetic confinement fusion device in an HL-2A device according to an embodiment of the present utility model;

FIG. 4 shows the upstream setup in a SOLPS program simulation according to an embodiment of the present utility modelDuring the process, the HL-2A is not inflated under the existing divertor configurationDeuterium and improved partial filter structure are filled in>Deuterium and filling after addition of the plasma window structure of the utility model +.>In the case of deuterium, electron density of the outer midplane +.>A section plane;

FIG. 5 shows the external midplane electron temperature for the same four cases as FIG. 4A section plane;

FIG. 6 shows the heat flux density of the outer divertor target plate of four cases identical to FIG. 4A section plane;

FIG. 7 shows electron temperature of the outer divertor target plate of four cases identical to FIG. 4A section plane;

FIG. 8 is a schematic representation of the simulated HL-2A prior art partial filter configuration under filling using the SOLPS programThe neutral gas pressure along the parting line varies from the outer midplane to the outer target plate while deuterium gas.

FIG. 9 is a schematic representation of the SOLPS program used to simulate the filling of an HL-2A divertor after the addition of the plasma window structure of the present utility modelThe neutral gas pressure along the parting line varies from the outer midplane to the outer target plate while deuterium gas.

In the figure:

1-main vacuum chamber, 11-X point, 2-divertor chamber, 21-divertor chamber throat, 22-divertor target plate, 3-plasma window, 4-air filling hole, 5-air extracting hole A, 6-air extracting hole B and 7-air extracting hole C.

Detailed Description

The principles and spirit of the present utility model will be described below with reference to several exemplary embodiments shown in the drawings. It should be understood that these embodiments are described only to enable those skilled in the art to better understand and to practice the utility model, and are not intended to limit the scope of the utility model in any way.

Referring to fig. 1 in combination with fig. 2 and 3, an embodiment of the present utility model provides a plasma window structure for mitigating the thermal load of a divertor in a magnetically confined fusion device.

As an example, the method is applied to an HL-2A tokamak device, wherein the HL-2A tokamak device belongs to one of magnetic confinement fusion devices, an elongated area is constructed between the throat of a divertor chamber and a main vacuum chamber of the HL-2A device to serve as a plasma window, an area where a target plate of the divertor is located is used as a high-pressure end of the plasma window, and an area, close to an X point, of the main vacuum chamber is used as a low-pressure end of the plasma window.

The divertor chamber throat portion narrows in width to about 2 cm and extends to the elongated region to form a plasma window, 20% in length cm.

And an air charging hole is arranged in the area of the divertor target plate in the divertor chamber and is used for charging neutral gas into the area of the divertor target plate to form a high-pressure end of the plasma window. Two pumping holes (pumping holes B and C) are added near the X point of the main vacuum chamber to form a low-pressure end of the plasma window. The extraction opening A is the existing extraction opening of the HL-2A device and is still reserved. Air suction of the air suction opening A, B, CAt rates of about 17.3 respectively、17.5/>And 16.7->

In one embodiment, the effect of the plasma window structure of the present utility model to mitigate the thermal load of a divertor is demonstrated by modeling the existing divertor configuration of a comparative HL-2A device and the target plate and upstream plasma parameters after the plasma window structure is incorporated into the divertor.

In this example, the SOLPS (Scape-Off Layer Plasma Simulator) program used for simulation consisted of two-dimensional fluid program B2.5 and Monte Carlo program EIRENE for simulation of neutral particles. Based on the existing typical plasma balance configuration of the single zero discharge of HL-2A, a calculation grid is generated, plasma transportation is simulated on a 96 (polar direction) x 36 (radial direction) quadrilateral grid, and neutral transportation is simulated on an additional triangular grid extending to the inner wall of the vacuum chamber. Selecting parameters within the H-mode discharge range of HL-2A, the total energy flow through the core-edge interface (CEI) in the simulationSet to 2MW, with electron and ion energy flows each half, 1 MW. The density of deuterium ions at CEI is set to +.>. CEI boundary in the simulation of this example is +.>At the top of the mesa region, typically at the time of an H-mode discharge. The types of particles included in the simulation included: deuterium atom->Deuterium ion->Electron e, and deuterium molecule +.>And molecular ion->. The drift term was temporarily disregarded in the simulation and sputtering of the first wall and the divertor material was ignored. Atomic molecular processes for the procedural process include ionization, recombination, charge exchange, dissociation, elastic collision, and the like. Since the plasma is assumed to be in steady state, the recirculation coefficients of the walls and target plate except for the extraction opening are all set to 1, i.e. 100% of the particles at the boundary enter the recirculation, while the absorption of 0.2 is set at the extraction opening location wall. The remaining boundary conditions are default and will not be described in detail herein.

To better illustrate how the effect of incorporating the plasma window structure of the present utility model to mitigate the divertor target plate, we simulated multiple cases under the same upstream boundary conditions, including: the vicinity of the target plate is not inflated under the existing divertor configuration of the HL-2A device (only the extraction opening A extracts air), and the vicinity of the target plate is inflated under the existing divertor configuration of the HL-2A device (only the extraction opening A extracts air)Deuterium gas, HL-2A device is filled in under the condition of contracting the throat part of the divertor (only the extraction opening A is used for extracting air)Deuterium gas and plasma window structure added into the bias filter of HL-2A device, i.e. the pumping hole A+B+C pumping is added under the condition of contracting throat part and increasing pumping hole>Deuterium gas.

Fig. 4 and 5 show the outer midplane density, temperature profile comparisons for the four cases described above. It can be seen that in the existing divertor configuration, the air is chargedDeuterium gas, which causes the upstream plasma density and temperature profile to vary greatly (square line and upper triangle line), electron density at the mid-plane parting line +.>Exceeding 1/3 lattice Lin Wode density limit +.>Normal discharge is not possible in the experiment; after the throat of the divertor is contracted (lower triangular line), the upstream density is reduced to a certain extent, but the requirements are still not met; if the pumping hole is added near the X-point on the basis, namely after the plasma window structure is added in the divertor (asterisk line), the density and the temperature profile of the upstream middle plane are more approximate to those of the conventional non-aerated condition (square line). Fig. 6 and 7 show a cross-sectional comparison of heat flux density and temperature of the outer divertor target plate for the same four cases described above. As can be seen from FIGS. 6 and 7, the temperature of the divertor target plate (+.>) Compared with the condition of no inflation) The heat flow of the target plate is greatly reduced by two orders of magnitude, and the effect of relieving the heat load of the target plate can be achieved.

Further, the distribution of neutral gas pressure can be used as an important parameter for measuring whether the plasma window structure of the present utility model can effectively block neutral gas. FIGS. 8 and 9 are, respectively, the HL-2A prior art divertor configuration and the fill after the plasma window configuration is addedIn deuterium gas, the polar neutral gas pressure varies along the parting line from the outer midplane to the outer target plate. As can be seen from the figure, the neutral gas pressure from the outer target plate to the vicinity of the X point is very high (10 Pa) in the conventional divertor configuration, which indicates that the neutral component has accumulated in the vicinity of the X point (at a distance of 2.7m from the inner target plate in the figure), but is added to the plasmaAfter the window structure, neutral gas can be gathered in the target plate area of the divertor (the neutral gas pressure can reach 30 Pa) and used for relieving the heat load of the target plate and does not enter the upstream (main vacuum chamber) of the target plate (the neutral gas pressure at the X point is lower than 0.5 Pa), so that the influence of neutral components on core plasma (main vacuum chamber) is reduced.

In general, this example demonstrates that by shrinking the divertor throat width and adding suction at the junction of the divertor chamber and the main vacuum chamber, a plasma window structure is incorporated into the divertor, achieving the effect of the plasma window blocking neutral gas and alleviating the thermal load of the divertor target plate, compared to the conventional approach of alleviating the thermal load of the target plate by filling neutral gas.

The utility model is described in detail herein using specific examples, and the modification of the structure of the divertor, the setting of the pumping rate and other setting of the boundary conditions in the above embodiments are only illustrative and not limitative, and other parameter values are also possible, and the description of the above embodiments is only for helping to understand the core idea of the utility model. It should be noted that any obvious modifications, equivalents, or other improvements to those skilled in the art without departing from the inventive concept are intended to be included in the scope of the present utility model.

Claims (2)

1. The utility model provides a plasma window structure for alleviating partial filter heat load in magnetic confinement fusion device, magnetic confinement fusion device includes main vacuum chamber and partial filter room, partial filter room is equipped with partial filter target plate, its characterized in that, partial filter room throat width is narrowed, and is constructed with long and narrow region and forms the plasma window between partial filter room throat narrowing position and main vacuum chamber, partial filter room is equipped with the high pressure end that the gas filling hole is used for filling neutral gas to partial filter target plate place region and forms the plasma window.

2. The structure of claim 1, wherein an extraction port is provided at the interface of the plasma window and the main vacuum chamber to prevent the non-ionized neutral gas remaining from the high pressure end from entering upstream of the main vacuum chamber.