Plasma-facing component

Abstract

A plasma-facing component comprising: an armour layer (101); and a heat sink (201) outboard of and in thermal contact with the armour layer (101); wherein: the heat sink (201) comprises: an impingement surface (211), and a jet array element (220) separated from the impingement surface (211) by a plenum space (231), the jet array element (220) comprising a plurality of jet inlet openings for gas jet impingement cooling of the impingement surface (211); wherein the impingement surface (211) comprises a copper-chromium-zirconium alloy material on which a plurality of pin fins is provided.

Description

PLASMA-FACING COMPONENTField of the Invention

[0001] The present invention relates generally to plasma-facing components for a nuclear fusion reactor. More specifically, the disclosure is concerned with improving cooling of plasma-facing components.Background

[0002] Designing plasma-facing components in a nuclear fusion reactor that relies on magnetic confinement of plasma requires consideration of the plasma edge processes, together with the material properties of the component. Of particular concern, in terms of material properties of the plasma-facing component, is how the plasma-facing component deals with a high thermal load. As well as the thermal load in ramp up, steady state, and ramp down operations of the fusion reactor, there is a particular challenge in dealing with high heat flux should plasma instability lead to a thermal shock load being applied to the plasma-facing component. Indeed, limiter plasma-facing components specifically are used, with adaptations that are intended to deal with the effects of plasma contact.

[0003] In addition to the design constraints resulting from the expected thermal loads, operational constraints relating to other features of the fusion reactor are also relevant to the design of plasma-facing components. For example, the overall dimensions of the fusion reactor, and the design of heat transfer systems for maintaining operation of the fusion reactor and extracting useable energy from the fusion reactor.

[0004] At present, such heat transfer systems are complex, typically having a large number of joints and other failure points which require continuous maintenance. In addition, there may be conflicting requirements from different systems in the fusion reactor to be as close as possible to the plasma, for efficient overall operation. Historically there has been a trade-off between systems. Naively one might say that the reactor surround simply be made as large as necessary to accommodate all of the various competing systems, however it will be appreciated that space is at a premium in the context of delivering commercially viable energy.

[0005] It is thus highly desirable to seek improvements to the way in which the plasmafacing components are designed, in order to enable better holistic fusion reactor design. It is desirable to enable effective thermal management of the plasma-facingcomponents without unduly increasing the radial dimension needed for the components, or requiring exotic alloys for the heat transfer components, while avoiding other space / size compromises associated with a liquid cooling strategy for plasmafacing components.Summary

[0006] The present invention is defined according to the independent claims. Additional features will be appreciated from the dependent claims and the description herein. Any embodiments which are described but which do not fall within the scope of the claims are to be interpreted merely as examples useful for a better understanding of the invention.

[0007] The example embodiments have been provided with a view to addressing at least some of the difficulties that are encountered with current approaches to designing plasma-facing components, whether those difficulties have been specifically mentioned above or will otherwise be appreciated from the discussion herein. In particular, the example embodiments aim to improve thermal performance of the plasma-facing component, such as without requiring the use of exotic alloys and such that a gas cooling strategy becomes viable, and while managing component count and complexity needed in the elements that supply cooling gas over a relatively large plasma-facing surface area.

[0008] In a first aspect of the invention there is provided a plasma-facing component comprising: an armour layer; and a heat sink outboard of and in thermal contact with the armour layer; wherein the heat sink comprises: an impingement surface, and a jet array element separated from the impingement surface by a plenum space, the jet array element comprising a plurality of jet inlet openings for gas jet impingement cooling of the impingement surface; wherein the impingement surface comprises a copper-chromium-zirconium alloy material on which a plurality of pin fins is provided.

[0009] To deal with the high heat flux through the plasma-facing component, a significant pumping power is required to deliver sufficient gas for the gas jet impingement cooling. Furthermore, to achieve relatively uniform heat transfer from the impingement surface, gas jet impingement techniques typically employ a high density of jet inlets, which also increases the required pumping power for a given area. The use of pin fins has been determined to be beneficial in heat transfer performance when convective resistance is much greater than conductive resistance for the heat sink. Assuch, the pin fins make a significant difference for heat sinks comprising a highly conductive material, such as CuCrZr, at the impingement surface. In addition, it has been determined that the mechanical properties of CuCrZr alloys allow the heat sink to be relatively thin, thus decreasing the conductive resistance and further contributing to the effectiveness of the pin fins in increasing heat transfer performance. The gas cooling approach as described takes full advantage of properties of CuCrZr, while avoiding the issues which may arise from liquid-gas phase change cooling, such as film-boiling, by direct impingement of the gas jets onto the CuCrZr material of the impingement surface.

[0010] The term inboard is used to mean the side of the plasma-facing component that is closest to the plasma, or a direction toward the plasma, in use. Correspondingly, the term outboard has the opposite sense. It will be understood that the plasma facing component may face toward the centre of a toroidal fusion reactor, toward the exterior, according to its arrangement in the plasma chamber, and that each of these orientations may comprise an inboard or an outboard direction according to the positioning of the plasma-facing component.

[0011] In one example, the plasma-facing component comprises a heat transfer layer between the armour layer and the heat sink. In one example, the heat transfer layer comprises a copper layer, such as a low-oxygen copper layer. In one example, the heat transfer layer is bonded to the armour layer, and / or to the heat sink. In one example, the heat transfer layer is in intimate thermal contact with the armour layer and the heat sink. In one example, the heat transfer layer provides a thermal bridge between the armour layer and the heat sink.

[0012] In one example, the armour layer comprises a plurality of armour tiles. In one example, the armour layer comprises a tungsten layer, or a layer comprising a tungsten alloy.

[0013] In one example, the jet array element is formed of copper-chromium-zirconium alloy material. In one example, the jet array element is formed of copper-chromium-zirconium alloy material such as to present a CuCrZr surface for impingement, such as an uncoated or otherwise uncovered surface.

[0014] In one example, the impingement surface is provided on an insert that is bonded to the heat sink. This simplifies manufacture of the component. In one example, the impingement surface is formed integrally with the pressure boundary of the heat sink.

[0015] In one example, the plasma-facing component is, in use, helium cooled.

[0016] In one example, the pin fins comprise an array of projections extending from the impingement surface. In one example, the pin fins are generally cylindrical. In one example, the pin fins extend generally perpendicularly from the impingement surface. In one example, the impingement surface is generally planar, and the jet inlet openings are arranged such that jets emitted therefrom are aligned generally parallel to an inboard-outboard axis, and generally in parallel to one another.

[0017] In one example, the pin fins are characterised by a pin height, a pin diameter and a pin spacing. In one example, the pin spacing, i.e. the distance between the centres of adjacent pins is constant in one direction, for example in two directions, such as two perpendicular directions. In one example, the plurality of pin fins is provided in a regular array, for example a square array.

[0018] In one example, the pin height is in the range 0.3mm to 1mm, such as 0.3mm, 0.5mm or 0.9mm

[0019] In one example, the pin diameter is in the range 0.25mm to 0.75mm, such as 0.5mm.

[0020] In one example, the pin spacing is between 0.75 mm and 2mm, such as 0.9mm, or 1.5mm.

[0021] In one example, the heatsink is greater than 0.5mm thick, such as greater than 1mm thick. For example the heatsink is 3mm thick.

[0022] In one example, the jet array element comprises a plurality of jet inlet openings arranged in a linear array. In one example, the plurality of jet inlet openings are arranged in a linear array with constant spacing. In one example, the jet array element comprises a plurality of jet inlet opening arrays, such as linear arrays lying parallel to but laterally offset from one another. In one example, the jet inlet openings in each linear array are spaced apart from one another by more than 3mm, for example 4mm, 6mm, 8mm or 10mm. In one example, the jet inlet openings of adjacent linear arrays are spaced apart by the same separation as adjacent jet inlet openings within the lineararrays. In one example, the jet inlet openings lie at the vertices of an array of isosceles triangles, such as identical isosceles triangles.

[0023] In one example, the jet diameter is 1mm. In one example, the ratio of jet diameter to pin diameter is between 3: 1 and 1:1, such as 2: 1.

[0024] In one example, the jet array element comprises a baffle that separates an inlet gas delivery volume from an outlet gas exhaust volume. In one example, the baffle defines a shared outlet from the plenum space for gas from the jet inlet openings, the shared outlet including the shared gas exhaust volume.

[0025] In one example, the baffle defines a shared inlet to the plenum space for inlet gas supplied to the first and second pluralities of jet inlet openings, the shared inlet including the shared inlet gas delivery volume.

[0026] In one example, in cross section the jet array element comprises a plurality of jet inlet openings inboard, with the baffle extending in an outboard direction to define a side wall of the shared outlet, for example extending in an outboard direction on one side of, or both sides of the plurality of jet inlet openings to define side walls of the outlet gas exhaust volume.

[0027] In one example, in cross section the jet array element comprises a plurality of jet inlet openings inboard, with the baffle extending in an outboard direction to define a side wall of a shared inlet, for example extending in an outboard direction on one side of, or both sides of the plurality of jet inlet openings to define side walls of the gas delivery volume.

[0028] In one example, in cross section the jet array element defines an alternating arrangement of inlet gas delivery volume and outlet gas exhaust volume, by way of the baffle side wall(s), or by way of the baffle side wall(s) and one or more structural ribs.

[0029] In one example, the plasma-facing component comprises a plate-type plasmafacing component. In one example, the plate type plasma-facing component comprises a plurality of plasma-facing components as herein described, formed integrally with each other.

[0030] In one example, the plasma-facing component comprises a plate-type plasmafacing component with an inboard-outboard depth dimension of less than 150mm, for example less than 100mm, such as 50mm. In one example, the plasma-facingcomponent comprises a plate-type plasma-facing component with a length dimension of greater than 100mm, for example greater than 250mm, such as 500mm. In one example, the plasma-facing component comprises a plate-type plasma-facing component with a width dimension of greater than 100mm, for example greater than 150mm, such as 250mm.

[0031] In one example, the structural ribs divide the plate type plasma-facing component into a plurality of units, each unit comprising the features of a plasma-facing component as herein described. In one example, the structural ribs divide the plate type plasma-facing component into a plurality of like units.

[0032] In a related aspect of the invention there is provided a nuclear fusion power system comprising a vacuum vessel within which a plasma is produced, and a plasmafacing component as herein described.Brief Description of the Drawings

[0033] For a better understanding of the present disclosure reference will now be made by way of example only to the accompanying drawings, in which:FIG. 1 shows a perspective view of an example plasma-facing component, with the inboard, plasma-facing surface visible toward the top;FIG. 2 shows a sectional perspective view illustrating pin fin parameters and the arrangement of the pin fins in a plasma-facing component;FIG. 3 shows a sectional view of a plasma-facing component illustrating example operating conditions;FIG. 4 shows cross sectional view within the plasma-facing component of FIG. 1, looking generally down the length thereof, the cross section taken generally across the width thereof roughly one third from the near end; andFIG. 5 shows four example sections of plasma-facing component, illustrating the material arrangement of an example embodiment, and four different arrangements of jet array elements.Detailed Description

[0034] At least some of the following example embodiments provide an improved design and construction for plasma-facing components, considering the thermal and structural requirements for limiters in a nuclear fusion reactor that operates using magnetically confined plasma. Other advantages and improvements may also be apparent from the discussed embodiments herein.

[0035] FIG. 1 shows a plasma-facing component 1. The plasma-facing component 1 comprises a plate-type limiter for a plasma fusion reactor, the plasma-facing component 1 comprising: an armour layer 101; and a heat sink 201 outboard of and in thermal contact with the armour layer 101.

[0036] The plate-type plasma-facing component 1 is relatively large, with example dimensions for length, width, and depth of 500mm, 250mm and 50mm. In other drawings, further representative example dimensions are provided, as are example material choices and other explanatory remarks and labels.

[0037] In use, the armour layer 101 faces the plasma, which is located inboard of the plasma-facing component 1. Since the plasma has an extremely high temperature, in use a significant heat flux is incident on, and correspondingly significant heat energy passes through the plasma-facing component 1. To resist this thermal stress, the armour layer 101 is made up of a plurality of tungsten armour tiles, which are of high melting point. The individual tiles are not separately labelled for the sake of simplicity, but as can be seen they are generally square shaped. In other embodiments, different tile materials and geometries are contemplated for the armour layer 101. For example, beryllium tiles, or rectangular tiles.

[0038] The plasma-facing component 1 is adapted so that its shape conforms, at least in the sense of being curved in the same directions, as the shape of the plasma boundary that it is to face in use. The curvature is achieved at a micro scale with slightly different thickness armour tiles, armour tiles of different thickness across their area, or the armour tile seating on the heat sink 201 at an angle to the heat sink 201 (or a combination of two or three of these adaptations). This improves the effectiveness of the plasma-facing component 1 in terms of resistance to the effects of the plasma, in use, and furthermore makes it easier to align a plurality of plasma-facing components accurately with respect to one another even when the plasma-facing components are of a larger plate-type construction.

[0039] To cope with the heat stress on the plasma-facing component 1, the heat sink 201 is arranged in thermal contact with the armour layer 101, and configured to carry heat from the plasma-facing component 1. In the embodiments shown, the heat sink 201 uses a gaseous cooling medium, in the form of helium gas, which provides jet impingement cooling for an impingement surface 211 made of CuCrZr and which is provided with a plurality of pin fins thereon. The pin fins of CuCrZr material are directly exposed to gaseous cooling medium, in use.

[0040] FIG. 2 shows cylindrical pin fins 212 on an impingement surface 211 of the heat sink 201, showing their height, diameter and separation in a square array. The heat sink 201 further comprises a jet array element 220 separated from the impingement surface 211 by a plenum space 231 , the jet array element 200 comprising a plurality of jet inlet openings 221 for gas jet impingement cooling of the impingement surface 211.

[0041] FIG. 3 shows a sectional view of a plasma-facing component 1, illustrating example operating conditions, with the armour layer 101 being exposed to a heat flux, q, of 3.41 MW per square metre.

[0042] The heat sink 201 is formed of copper-chromium-zirconium alloy material, with a heat transfer layer 301 between the armour layer 101 and the heat sink 201. The heat transfer layer 301 comprises a low-oxygen copper layer that is bonded to the armour layer 101, and to the heat sink 201 to provides a thermal bridge therebetween. A difference in thermal expansion between the material of the armour layer 101 and the CuCrZr heat sink 201, principally due to difference in coefficient of thermal expansion, but also to an extent due to temperature gradients when in use, could cause high stresses at the interface. This introduces a risk of delamination or yielding of either component. The heat transfer layer 301 provides a degree of mechanical adaptability, as it is able to creep and thus take up a differential strain without causing failure of the bond between the parts. The high thermal conductivity of copper minimises the negative thermal conduction impact of adding more material at the thermal bridge 301.

[0043] The temperature Ts at the interface between the CuCrZr material and the copper heat transfer layer 301 is limited to 350 degrees C, so that the heatsink 201 maintains structural integrity. Jets of helium gas, at temperature Tf of 200 degrees C impinge on the impingement surface 211, and the pin fins 212 thereon, carrying away heat from the heatsink 201. In this example 1mm diameter jet are used. The helium jets are delivered from the jet array element 220, through the plenum space 231.

[0044] As will be appreciated, the high thermal conductivity of the CuCrZr heatsink 201 means that convective heat transfer dominates the removal of heat by jet impingement cooling, and as such the presence of pin fins produces a marked improvement in cooling performance. For other materials, in order to achieve comparable cooling, the thickness of the heatsink would have to be reduced to unworkably small thickness, compromising the mechanical stability thereof. In the example of FIG. 3, pumping power for the cooling gas is set at 50kW per square metre, and the inventors have determined that the presence of pin fins increases the cooling effectiveness without unduly increasing the required pumping power. That is, there is a benefit, in the CuCrZr heat sink cooled by helium jets, to having the jets impinge on pin fins, a benefit beyond that achieved by simply upping the pumping power to a comparable level that accounts for the extra resistance produced by the pin fins.

[0045] FIG. 4 and FIG. 5 show a practical implementation of a heat sink 201, in which a first plurality of jet inlet openings 221 for gas jet impingement cooling of the impingement surface 211; and a second plurality of jet inlet openings 222 for gas jet impingement cooling of the impingement surface 211 are provided in the jet array element 220. The jet array element 220 further comprises a baffle 223 defining a shared outlet from the plenum space 231 for gas from the first and second pluralities of jet inlet openings 221, 222. The baffle 223 may also be referred to as an inlet / outlet divider. The shared outlet lies outwardly and between the first and second pluralities of jet inlet openings 221, 222, between side wall portions of the baffle 223, labelled as 224 and 225. Int these embodiments, the heat sink 201 of the plasma-facing component 1 provides integrated, internal manifolding for the gaseous cooling medium.

[0046] In the example embodiment of FIG. 4 and FIG. 5, the plenum space 231 extends along the length of the plasma-facing component 1 , as do each of the jet inlet openings, the pin fins on the impingement surface and furthermore as does the shared outlet.

[0047] The plenum space 231, and shared outlet therefrom, together with the baffle 233 comprise an internal manifolding arrangement for gas movement through the heat sink 201. The plenum space 231 defines an unobstructed volume for the delivery of cooling gas from the jet inlet openings onto the impingement surface 211 and defines an unobstructed volume for the removal of cooling gas from the impingement surface 211 to the shared outlet, in the sense that the cooling gas is not constrained in channels, or by other macro features of the impingement surface 211. The jet inlet openings 221 are arranged opposite the impingement surface 211 , such that jets emitted from the jetinlet openings 221 perpendicular to the impingement surface 211. The impingement surface 211 is generally planar and the jet inlet openings 221 are arranged such that jets emitted therefrom are aligned generally parallel to an inboard-outboard axis, and generally in parallel to one another. With this arrangement, the jets impinge on the pin fins on the impingement surface in a direction that is parallel to the height direction of the pin fins as they extend from the impingement surface 211.

[0048] To give scalability, the jet array element 220 is supported between two structural ribs 240, with a plurality of unit elements as described formed alongside one another, between the structural ribs 240. The structural ribs 240 run the length of the plasmafacing component 1, and further contribute to gas distribution within the heat sink 201, both within the unit elements, and between them.

[0049] The baffle 223 partially bounds an inlet gas delivery volume for the jet array element 220, the inlet gas delivery volume defined between an inlet manifold 250 for receiving cooling gas, and jet openings of the jet array element 220. The baffle 223 and / or one or more structural rib 240 that support the jet array element 220 bound the inlet gas delivery volume for the jet array element 220, the inlet gas delivery volume defined between an inlet manifold 250 for receiving cooling gas, and jet openings of the jet array element 220. As can be discerned from FIG. 3, the cross section of the inlet gas delivery volume decreases with distance along the inlet gas delivery volume, decreasing with distance from the inlet manifold 250. This tapered arrangement helps with even distribution of cooling gas through the jets 231. To support removal of heat from the heat sink 201 as the gas moves through the inlet and outlet passageways formed by the baffle 223 and the ribs 240, these components are also formed of a CuCrZr material.

[0050] The baffle 223 bounds an outlet gas exhaust volume for the jet array element 220, the outlet gas exhaust volume defined between the plenum space 231 and an outlet manifold, or exhaust manifold for receiving used cooling gas. The baffle 223 and structural ribs 240 that support the jet array element 220 bound the outlet gas exhaust volume for the jet array element 220, with the outlet gas exhaust volume defined between the plenum space 231 and an outlet manifold.

[0051] The baffle 223 separates the inlet gas delivery volume from the outlet gas exhaust volume, such that the change in cross section in one is reflected by the change in cross section of the other along the respective lengths thereof, with the cross sectionof the inlet gas delivery volume decreasing along its length, to even out delivery of gas, and the outlet gas exhaust volume also decreasing along its length to concentrate the flow of exhaust used cooling gas. The baffle 223,

[0052] In the first example shown in FIG. 5, the baffle 223 defines a shared outlet from the plenum space 231 for gas from first, second and third pluralities of jet inlet openings 221, 222, 223, with shared outlets therebetween, communicating with the respective shared gas exhaust volume. In this embodiment, the structural ribs 240 contribute to gas manifolding on the inlet side, but on the outlet side, the baffle 233 is primarily responsible for this function.

[0053] The other examples in FIG. 5 show different arrangements of jet array elements 220, with various shapes of baffle 223 defining shared inlets to the plenum space 231 for inlet gas supplied to the first and second pluralities of jet inlet openings, inlet including the shared inlet gas delivery volume. The jet spacing varies between these examples, for example 4mm, 6mm, 8mm and 10mm jet spacings being used. In the examples of FIG. 5, in cross section the jet array elements 220 define an alternating arrangement of inlet gas delivery volume and outlet gas exhaust volume, by way of the baffle 223 side wall(s), or by way of the baffle 223 side wall(s) and one or more structural rib 240. Different jet inlet openings, for example different spacings and sizes, are also provided, according to the specified cooling performance required of the plasma-facing component 1.

[0054] The structural ribs 240 divide the plate type plasma-facing component into a plurality of units, each unit comprising the features of a plasma-facing component as herein described. The structural ribs 240 suitably divide the plate type plasma-facing component 1 into a plurality of like units, which are supplied from shared inlet manifold 250 for cooling gas, which may also be referred to as a shared primary inlet, and discharge used cooling gas from a shared outlet manifold, which may be referred to as a shared primary exhaust. The shared primary input 250 runs transverse to the structural rib 240, passing adjacent to the ends thereof, and running transverse thereto. The shared primary input and shared primary exhaust are located at opposite ends of a structural rib 240 in each unit.

[0055] The shared primary exhaust communicates used cooling gas to an overall plate outlet, which is not shown. The shared primary input receives cooling gas from an overall plate inlet 205 identified in FIG. 4. Said overall plate inlet and outlet facilitateconnection to a gas supply and exhaust system. In various embodiments concentric overall inlet and outlets may be used to reduce the effect of thermal stresses, and these may be located centrally, or at a corner, or edge of the plate-type plasma-facing component 1.

[0056] FIG. 5 again shows material components of the plasma-facing component 1. That is, the armour layer 101 comprises tungsten, as previously mentioned. The heat sink 201 is formed of copper-chromium-zirconium alloy material, with a heat transfer layer 301 between the armour layer 101 and the heat sink 201. The heat transfer layer 301 is labelled only in the enlarged view, for the sake of clarity. The heat transfer layer 301 comprises a low-oxygen copper layer that is bonded to the armour layer 101, and to the heat sink 201 to provides a thermal bridge therebetween.

[0057] Also visible in the enlarged section, the impingement surface 211 is provided with the plurality of pin fins 212 thereon, to aid in heat transfer from the impingement of gas jets on the impingement surface 211.

[0058] To aid manufacturing, the jet array element 220, impingement surface 211, heat transfer layer 301 and armour layer 101 may be manufactured separately and bonded to one another. Ideally, the impingement surface 211 is formed integrally with the pressure boundary of the heat sink 201.

[0059] The increase in heat transfer from the heat sink as described is proportionally greater than is achieved by simply increasing the pumping power for the jets. The pin fins improve the heat transfer coefficient considerably, to a point where standard materials with gas coolant become viable for limiter construction.

[0060] Various combinations of optional features have been described herein, and it will be appreciated that described features may be combined in any suitable combination. In particular, the features of any one example embodiment may be combined with features of any other embodiment, as appropriate, except where such combinations are mutually exclusive. Throughout this specification, the term “comprising” or “comprises” means including the component(s) specified but not to the exclusion of the presence of others.

[0061] Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

[0062] All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive.

[0063] Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent, or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

[0064] The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

CLAIMS1. A plasma-facing component (1) comprising:an armour layer (101); anda heat sink (201) outboard of and in thermal contact with the armour layer (101); wherein:the heat sink (201) comprises:an impingement surface (211), anda jet array element (220) separated from the impingement surface (211) by a plenum space (231), the jet array element (220) comprising a plurality of jet inlet openings (221) for gas jet impingement cooling of the impingement surface (211); wherein the impingement surface (211) comprises a copper-chromium-zirconium alloy material on which a plurality of pin fins (212) is provided.

2. The plasma-facing component (1) of claim 1, further comprising a copper heat transfer layer (301) between the armour layer (101) and the heat sink (201).

3. The plasma-facing component (1) of claim 1 or 2, wherein the jet array (220) element is formed of copper-chromium-zirconium alloy material.

4. The plasma-facing component (1) of any preceding claim, wherein the impingement (211) surface is formed integrally with a pressure boundary of the heat sink (201).

5. The plasma-facing component (1) of any preceding claim, wherein the pin fins (212) are provided as an array of generally cylindrical projections extending from the impingement surface (211).

6. The plasma-facing component (1) of any preceding claim, wherein the pin fins (212) extend generally perpendicularly from the impingement surface.

7. The plasma-facing component (1) of any preceding claim, wherein the impingement surface (211) is generally planar, and the jet inlet openings are arranged such that jets emitted therefrom are aligned generally parallel to an inboard-outboard axis, and generally in parallel to one another.

8. The plasma-facing component (1) of any preceding claim, wherein the pin fins are provided in an equally spaced square array.

9. The plasma-facing component (1) of any preceding claim, wherein the jet array element (220) comprises a plurality of jet inlet openings (221) arranged in a linear array.

10. The plasma-facing component (1) of any preceding claim, wherein the jet array element (220) comprises a plurality of jet inlet openings (211 , 222) that lie at the vertices of an array of isosceles triangles.

11. The plasma-facing component (1) of any preceding claim, wherein the jet array element (220) comprises a baffle (223) that separates an inlet gas delivery volume from an outlet gas exhaust volume.

12. The plasma-facing component (1) of claim 11 , wherein the baffle (223) comprises a CuCrZr material.

13. The plasma-facing component (1) of any preceding claim, wherein the plenum space (231) defines an unobstructed volume for the delivery of cooling gas from the jet inlet openings (221, 222) onto the impingement surface (211) and an unobstructed volume for the removal of cooling gas from the impingement surface (211) to a shared outlet.

14. The plasma-facing component (1) of any preceding claim, wherein the jet array element (220) is supported by, and between, structural ribs (240).

15. The plasma-facing component (1) of claim 14, wherein the structural ribs (240) are integrally formed with the jet array element (220) and run the length of the plasmafacing component (1).

16. The plasma-facing component (1) of claim 14 or 15, wherein the structural ribs comprise a CuCrZr material.

17. A nuclear fusion power system, comprisinga vacuum vessel within which a plasma is produced,a plasma-facing components comprising the features of any preceding claim.

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