magnetic mirror device

Abstract

The magnetic mirror device (200) comprises a first inner coil (104) arranged to conduct current in a first direction, and a second inner coil (105) axially offset from the first inner coil (104) and arranged to conduct current in a second direction opposite the first direction. The mirror device (200) further comprises a first outer coil (210) positioned radially outward of the first inner coil (104) and arranged to conduct current in the second direction, and a second outer coil (212) positioned radially outward of the second inner coil (105) and arranged to conduct current in the first direction.

Description

[Technical Field]

[0001] FIELD OF THE DISCLOSURE The present disclosure relates to magnetic mirror devices and methods of operating magnetic mirror devices. [Background technology]

[0002] Significant efforts are being made to design nuclear reactors for controlled nuclear fusion on Earth. The most promising fusion process involves the use of the hydrogen isotope deuterium ( 2 H) and tritium ( 3 H). The deuterium-tritium fusion process has a kinetic energy of about 3.5 MeV. 4 It produces He alpha particles and neutrons with a kinetic energy of approximately 14.1 MeV.

[0003] For fusion to occur, the nuclei must be in the form of a plasma with a temperature on the order of 150 million Kelvin. Providing confinement for such a plasma remains a major challenge.

[0004] Plasma confinement involves the confinement of charged particles in the plasma. There are several different known magnetic configurations for plasma confinement. A well-known class of designs is the magnetic mirror device. In it, particles follow magnetic field lines through the magnetic mirror device and are reflected by regions of increased magnetic flux density in the surrounding area of ​​the device.

[0005] One configuration of magnetic mirror devices known in the prior art is the linear bottle configuration. Another configuration of magnetic mirror devices known in the prior art is the biconic cusp, in which a first coil is arranged to conduct current in a first direction and a second coil is arranged to conduct current in a second direction opposite the first direction, with the first and second coils longitudinally displaced within the device. Two parallel electromagnets thus formed, with currents flowing in opposite directions, generate oppositely directed electromagnetic fields that can interact to form a plasma confinement region between the coils.

[0006] There is a constant need to improve such devices. Summary of the Invention

[0007] It is an object of the present disclosure to solve or at least mitigate the above problems.

[0008] To this end, according to a first aspect, there is provided a magnetic mirror apparatus comprising: a first inner coil arranged to conduct current in a first direction; and a second inner coil axially offset from the first inner coil and arranged to conduct current in a second direction opposite to the first direction, wherein the plasma confinement device further comprises a first outer coil located radially outward of the first inner coil and arranged to conduct current in the second direction; and a second outer coil located radially outward of the second inner coil and arranged to conduct current in the first direction.

[0009] Thus, compared to the biconic cusps known in the prior art, the present invention adds a first outer coil located radially outside the first inner coil and a second outer coil located radially outside the second inner coil.

[0010] This allows for the generation of a central plasma confinement region located at the center of the plasma confinement device, as well as an outer annular plasma confinement region having similar magnetic field characteristics, the annular plasma confinement region being located radially outward of the central plasma confinement region. Due to its annular geometry, the outer plasma confinement region may enable a significantly larger confined plasma volume to be achieved for a given magnetic mass compared to the central plasma confinement region having the compact geometry of a biconic cusp. Furthermore, this configuration allows the outer plasma confinement region to present concave magnetic field lines as viewed from outside the outer plasma confinement region, which are known to be related to magnetohydrodynamic stability of the confined plasma.

[0011] According to another aspect, there is provided a fusion reactor comprising the magnetic mirror device of the first aspect, which may generally exhibit the same features and advantages as the first aspect.

[0012] According to another aspect, there is provided the use of the magnetic mirror device of the first aspect in a nuclear fusion reactor, which may generally exhibit the same features and advantages as the first aspect.

[0013] According to another aspect, there is provided a method of operating a magnetic mirror device, the method comprising: a first inner coil of the magnetic mirror device conducting current in a first direction; a second inner coil of the magnetic mirror device axially offset from the first inner coil and conducting current in a second direction opposite the first direction; a first outer coil of the magnetic mirror device located radially outward of the first inner coil and conducting current in the second direction; and a second outer coil of the magnetic mirror device located radially outward of the second inner coil and conducting current in the first direction. This aspect may generally exhibit the same features and advantages as the first aspect.

[0014] The method may be performed to confine the plasma.

[0015] The method may be carried out in a fusion reactor.

[0016] The above and additional objects, features, and advantages of the present disclosure will be better understood through the following illustrative and non-limiting detailed description of preferred embodiments, with reference to the accompanying drawings in which like reference numerals are used for like elements and in which: [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a cross-sectional plan view of a magnetic mirror device having a biconic cusp configuration. [Figure 2] FIG. 1 is a cross-sectional plan view of a magnetic mirror device. DETAILED DESCRIPTION OF THE INVENTION

[0018] As is generally known, plasma confinement devices can be based on either open or closed magnetic field lines.

[0019] A closed magnetic field configuration can be realized, for example, in a toroidal magnetic field, an example of such a device being a tokamak.

[0020] An open magnetic field line plasma confinement device, as known per se in the prior art, may operate by the principle of magnetic mirroring, in which charged particles of the plasma are reflected by a region of increased magnetic flux density in the peripheral part of the confinement region.

[0021] The magnetic mirror device may be a linear magnetic mirror device with a first mirror region located at a first end of the magnetic mirror device and a second mirror region located at a second end of the linear magnetic mirror device. Alternatively, magnetic mirror devices with more elaborate configurations having more than two mirror regions are equally possible, such as in the case of a biconic cusp or in the case of the inventive concepts described in more detail below.

[0022] Although recognized to provide plasma confinement, open field line plasma confinement devices always suffer from leakage of charged particles with velocity vectors sufficiently aligned with the magnetic field lines. More specifically, the Miller effect occurs for all particles within an approach angle outside the loss cone defined by the helical pitch angle of the charged particle's orbital spin around the magnetic field lines.

[0023] The size of the loss cone is determined by the maximum magnetic flux density B in the mirror region, which follows the magnetic field lines. mirror and the minimum magnetic flux density B in the central region of the plasma confinement region central The mirror ratio r is defined as the ratio of mirror is determined by the following:

number

[0024] The angles that define the loss cone are then:

number

[0025] Therefore, it can be seen that a high mirror ratio results in a small loss cone, and as a result, only particles with velocities most aligned with the magnetic field lines escape. Conversely, a low mirror ratio results in a large loss cone.

[0026] It is known from the literature that a characteristic of the magnetic field lines of a plasma confinement device that is relevant to the magnetohydrodynamic stability of the confined plasma is a concave magnetic field, i.e. a magnetic field with concave magnetic field lines, as viewed from outside the plasma confinement region and the confined plasma.

[0027] Throughout this disclosure, reference will be made to diagrams showing simulated magnetic field lines, i.e., isopotential lines.

[0028] 1, presented as an example useful for understanding the concepts of the present invention, is a cross-sectional plan view of a magnetic mirror device 100 having a biconic cusp configuration. In the example of FIG. 1, the magnetic mirror device 100 is rotationally symmetric, or at least substantially rotationally symmetric, about an axis of symmetry A, which lies in the plane of FIG. 1.

[0029] The magnetic mirror device 100 may be used for plasma confinement and may include conventional shielding and / or a plasma vessel 102 known in the art. The shielding may include neutron shielding known per se. In particular, the magnetic mirror device 100 may be included in and / or used in a nuclear fusion reactor.

[0030] As can be seen from Figure 1, the magnetic mirror device 100 comprises a plurality of electromagnetic coils, namely two electromagnetic coils 104 and 105. Each electromagnetic coil 104, 105 may be arranged in a circular loop as in Figure 1 and may be arranged to conduct a respective direct current, the direction of which is conventionally indicated in Figure 1 using a respective dot or cross.

[0031] In particular, the magnetic mirror device 100 includes a plurality of electromagnetic coils 104, 105, conventionally marked with a dot and a cross in FIG. 1, which comprises a first coil 104 arranged to conduct current in a first direction, and a second coil 105 axially offset from the first coil and arranged to conduct current in a second direction opposite the first direction.

[0032] 1, as is apparent from the figure, multiple electromagnetic coils 104, 105 may be arranged coaxially with respect to the axis of symmetry A in the example of Figure 1. Furthermore, the coils 104, 105 may be spaced apart longitudinally with respect to the axis of symmetry A.

[0033] As known per se in the art, the biconic cusp electromagnetic coil configuration exemplified by the magnetic mirror apparatus 100 of FIG. 1 makes it possible to generate a plasma confinement region 106 located in the center of the plasma confinement device 100.

[0034] The magnetic field configuration of Figure 1 has no toroidal component, i.e., no magnetic field component perpendicular to the cross section of the figure.

[0035] 1, the plasma confinement region 106 is limited by the respective mirror regions 108a,b,c of increased magnetic flux density compared to the region around the center C of the magnetic mirror device, as evidenced by the magnetic field line spacing in each mirror region 108a,b,c compared to the region around the center C, and as known per se in the art. In other words, each respective mirror region 108a,b,c has magnetic field lines that converge as they are approached from the region around the center C of the magnetic mirror device 100. In particular, in the biconic cusp field configuration of the magnetic mirror device 100 of FIG. 1, there are more than two mirror regions 108a,b,c, i.e., three mirror regions 108a,b,c.

[0036] The first mirror region 108a is formed between the first coil 104 and the second coil 105 at the outer radial periphery of the plasma confinement region 106. Thus, the magnetic field lines in the first mirror region 108a extend radially of the magnetic mirror device 100, i.e., perpendicular to the axis of symmetry A.

[0037] The second mirror region 108b is formed radially inward of the first coil 104, around the axially lower side of the plasma confinement region 106. In other words, the first coil 104 is located radially outward of the second mirror region 108b. Therefore, the magnetic field lines in the second mirror region 108b generally extend in the longitudinal direction of the magnetic mirror device 100, i.e., along the axis of symmetry A.

[0038] The third mirror region 108c is formed radially inward of the second coil 105 around the upper axial side of the plasma confinement region 106. In other words, the second coil 105 is located radially outward of the third mirror region 108c. Therefore, the magnetic field lines in the third mirror region 108c generally extend in the longitudinal direction of the magnetic mirror device 100, i.e., along the axis of symmetry A.

[0039] Therefore, the plasma confinement region 106 has a compact topology around the center point C of the magnetic mirror device 100 and therefore does not have any holes. In the example of Figure 1, the plasma confinement region has rotational symmetry about the axis of symmetry A.

[0040] 2 is a cross-sectional plan view of a magnetic mirror device 200. In the example of FIG. 2, the magnetic mirror device 200 is rotationally symmetric, or at least substantially rotationally symmetric, about an axis of symmetry A which lies in the plane of FIG.

[0041] The magnetic mirror device 200 may be used for plasma confinement and may include conventional shielding known in the art and / or a plasma vessel 102. The shielding may include neutron shielding known per se. In particular, the magnetic mirror device 200 may be included in and / or used in a nuclear fusion reactor.

[0042] As can be seen from Figure 2, the magnetic mirror device 200 includes a plurality of electromagnetic coils 104, 105, 210, and 212, i.e., four electromagnetic coils 104, 105, 210, and 212. Each of the electromagnetic coils 104, 105, 210, and 212 may be arranged in a circular loop as in Figure 2, and may be arranged to conduct a respective direct current, the direction of which is conventionally indicated in Figure 2 using a respective dot or cross.

[0043] Similar to the magnetic mirror device 100 of FIG. 1 having a biconic cusp magnetic field configuration, the magnetic mirror device 200 of FIG. 2 comprises a first inner coil 104 arranged to conduct current in a first direction and a second inner coil 105 axially offset from the first inner coil and arranged to conduct current in a second direction opposite the first direction.

[0044] The magnetic field configuration of Figure 2 has no toroidal component, i.e., no magnetic field component perpendicular to the cross section of the figure.

[0045] In the configuration of FIG. 2, as is apparent from the figure, the first inner coil 104 and the second inner coil 105 may be arranged coaxially with respect to the axis of symmetry A in the example.

[0046] In addition to the configuration of the magnetic mirror device 100 in FIG. 1, the magnetic mirror device 200 includes a first outer coil 210 and a second outer coil 212 .

[0047] The first outer coil 210 is located radially outside the first inner coil 104 with respect to the axis of symmetry A. Therefore, the first inner coil 104 and the first outer coil 210 are arranged concentrically.

[0048] The first outer coil 210 is positioned to conduct current in a second direction, ie, in the same direction as the current conducted by the second inner coil 105 .

[0049] The second outer coil 212 is located radially outward of the second inner coil 105 with respect to the axis of symmetry A. Therefore, the second inner coil 105 and the second outer coil 212 are arranged concentrically.

[0050] The second outer coil 212 is positioned to conduct current in a first direction, ie, the same direction as the current conducted by the first inner coil 104 .

[0051] For example, the absolute values ​​of the respective currents conducted by each of the first inner coil 104, the second inner coil 105, the first outer coil 210, and the second outer coil 212 may be equal. Alternatively, two or more coils may conduct currents having unequal absolute values.

[0052] Similar to the biconic cusp electromagnetic coil configuration of FIG. 1, the coil arrangement of the magnetic mirror apparatus 200 of FIG. 2 allows for placement of a central plasma confinement region 106 located at the center C of the plasma confinement device 100 .

[0053] 2, the central plasma confinement region 106 is bounded by the respective mirror regions 108a,b,c of increased magnetic flux density relative to the region around the center C of the magnetic mirror device 200, as evidenced by the magnetic field line spacing in each mirror region 108a,b,c and the region around the center C of the magnetic mirror device, similar to the biconic cusp configuration of FIG. 1. In other words, each respective mirror region 108a,b,c has magnetic field lines that converge as they are approached from the center C of the magnetic mirror device 200. Notably, the central plasma confinement region has more than two mirror regions, i.e., three mirror regions 108a,b,c.

[0054] As is clear from FIG. 2, the second inner coil 105 and the second outer coil 212 may be arranged in mirror symmetry on the symmetry plane P with respect to the first inner coil 104 and the first outer coil 210.

[0055] The first mirror region 108a of the central plasma confinement region 106 is formed between the first inner coil 104 and the second inner coil 105 at the outer radial periphery of the central plasma confinement region 106. Thus, the magnetic field lines in the first mirror region 108a generally extend radially of the magnetic mirror device 200, i.e., perpendicular to the axis of symmetry A.

[0056] The second mirror region 108b of the central plasma confinement region 106 is formed radially inward of the first inner coil 104, around the axially lower side of the central plasma confinement region 106. In other words, the first inner coil 104 is located radially outward of the second mirror region 108b. Therefore, the magnetic field lines in the second mirror region 108b generally extend in the longitudinal direction of the magnetic mirror device 200, i.e., along the axis of symmetry A.

[0057] The third mirror region 108c of the central plasma confinement region 106 is formed radially inward of the second inner coil 105, around the upper axial periphery of the plasma confinement region 106. Thus, the magnetic field lines in the third mirror region 108c generally extend in the longitudinal direction of the magnetic mirror device 200, i.e., along the axis of symmetry A.

[0058] Therefore, the central plasma confinement region 106 has a compact topology around the center point C of the magnetic mirror device 200 and therefore does not have any holes. The plasma confinement region has rotational symmetry about the axis of symmetry A.

[0059] In addition to the central plasma confinement region 106, and unlike the biconic cusp configuration of the magnetic mirror device 100 of FIG. 1, the coil arrangement of the magnetic mirror device 200 of FIG. 2 allows for the placement of a further plasma confinement region in the form of an outer plasma confinement region 206, which has an annular topology.

[0060] 2, the outer plasma confinement region 206 is bounded by the respective mirror regions 108a, 208b, c, d of increased magnetic flux density relative to the central region of the outer plasma confinement region 206, as evidenced by the magnetic field line spacing in each mirror region 108a, 208b, c, d and the central region of the outer plasma confinement region 206. The central region of the plasma confinement region 206 is located axially between the first inner coil 104 and the first outer coil 210 on the one hand and the second inner coil 105 and the second outer coil 212 on the other hand. The central region of the outer plasma confinement region 206 is located radially between the first inner coil 104 and the second inner coil 105 on the one hand and the first outer coil 210 and the second outer coil 212 on the other hand.

[0061] In other words, each respective mirror region 108a, 208b, c, d of the outer plasma confinement region 206 has converging magnetic field lines. In particular, the outer plasma confinement region 206 has more than two mirror regions, i.e., four mirror regions 108a, 208b, c, d.

[0062] The first mirror region 108a of the outer plasma confinement region 206 is identical to the first mirror region 108a of the central plasma confinement region 106 and is formed between the first inner coil 104 and the second inner coil 105 at the inner radial periphery of the outer plasma confinement region 206. Thus, the magnetic field lines in the first mirror region 108a generally extend radially of the magnetic mirror device 200, i.e., perpendicular to the axis of symmetry A.

[0063] The second mirror region 208d of the outer plasma confinement region 206 is formed between the first outer coil 210 and the second outer coil 212 at the outer radial periphery of the outer plasma confinement region 206. Thus, the magnetic field lines in the second mirror region 208d generally extend radially of the magnetic mirror device 200, i.e., perpendicular to the axis of symmetry A.

[0064] The third mirror region 208b of the outer plasma confinement region 206 is formed radially between the first inner coil 104 and the first outer coil 210 around the lower axial periphery of the outer plasma confinement region 206. Thus, the magnetic field lines in the third mirror region 208b generally extend longitudinally of the magnetic mirror device 200, i.e., parallel to the axis of symmetry A.

[0065] The fourth mirror region 208c of the outer plasma confinement region 206 is formed radially between the second inner coil 105 and the second outer coil 212 around the upper axial periphery of the outer plasma confinement region 206. Thus, the magnetic field lines in the fourth mirror region 208c generally extend longitudinally of the magnetic mirror device 200, i.e., parallel to the axis of symmetry A.

[0066] Thus, the outer plasma confinement region 206 has an annular or donut-shaped topology, i.e., holes, radially outward from the axis of symmetry A. The outer plasma confinement region 206 has rotational symmetry about the axis of symmetry A.

[0067] As is evident from FIG. 2, the central plasma confinement region 106 and the outer plasma confinement region 206 may exhibit concave magnetic field lines as viewed from outside the respective plasma confinement regions, which are associated with magnetohydrodynamic stability of the confined plasma.

[0068] Typical dimensions of the magnetic mirror device 200 of FIG. 2 may be as follows:

[0069] The distance between the first inner coil 104 and the second inner coil 105 and the distance between the first outer coil 210 and the second outer coil 212 may be in the range of 1 to 2 m, preferably about 2.2 m.

[0070] The first inner coil 104, the first outer coil 210, the second inner coil 105, and the second outer coil 212 may have a height in the range of 1 to 2 m, preferably about 1.1 m.

[0071] The first inner coil 104 and the second inner coil 105 may each have an inner radius in the range of 1 to 2 m, preferably about 2.2 m.

[0072] The first inner coil 104 and the second inner coil 105 may each have an outer radius in the range of 3 to 7 m, preferably about 6.2 m.

[0073] The first outer coil 210 and the second outer coil 212 may each have an inner radius in the range of 5 to 10 m, preferably about 8.65 m.

[0074] The first outer coil 210 and the second outer coil 212 may each have an outer radius in the range of 8 to 20 m, preferably about 11.1 m.

[0075] Throughout this disclosure, each electromagnetic coil may be manufactured and arranged using methods, materials, compounds, etc. known per se in the art, for example using copper or some other suitable metal as the conductor.

[0076] Alternatively, each electromagnetic coil may be a superconductor coil. Suitable superconductor materials may include YBCO, Bi2223, 2212, Nb3SN, NbTi, MgB2, and / or ReBCO. Throughout this disclosure, the electromagnetic coils may be, for example, so-called high temperature superconductor coils.

[0077] As is known in the art, superconductor coils may comprise an internal structure. For example, within each superconductor coil, the superconducting material may be arranged in filaments, strands, cables, ropes, or the like, using methods commonly known in the art. In this case, the cross-section of the coil referred to throughout this disclosure should be understood as the surrounding envelope of this internal structure.

[0078] For example, throughout this disclosure, superconductor coils may be fabricated and arranged using methods, materials, and compounds such as those detailed in D Uglietti: A review of commercial high temperature superconducting materials for large magnets: from wires and tapes to cables and conductors, Supercond. Sci. Technol. 32 (2019) 053001 (29pp), https: / / doi.org / 10.1088 / 1361-6668 / ab06a2, which is incorporated herein by reference.

[0079] Furthermore, the superconductor coil may be cooled using methods generally known per se in the art.

[0080] Single particle simulations have shown that the confinement in the central plasma confinement region 106 and outer plasma confinement region 206 of the magnetic mirror device 200 of FIG. 2 exhibits similar confinement performance to the plasma confinement region 106 of the magnetic mirror device 100 with the biconic cusp configuration of FIG. 1, but provides a significantly larger plasma confinement volume, in this example, approximately 16 times larger than achievable with the same magnetic mass.

[0081] The physical dimensions of the magnetic mirror device 200 may depend on many parameters, such as, for example, the optical current density in the magnetic coils, the degree of alpha particle confinement, and the desired plasma volume.

[0082] The inventive concept has been described above primarily with reference to exemplary embodiments. However, as will be readily recognized by those skilled in the art, embodiments other than those disclosed above are equally possible within the scope of the inventive concept as defined by the appended claims.

Claims

1. A magnetic mirror device (200), a first inner coil (104) arranged to conduct current in a first direction; a second inner coil (105) axially offset from the first inner coil (104) and arranged to conduct current in a second direction opposite the first direction; Equipped with The magnetic mirror device (200) a first outer coil (210) positioned radially outward of the first inner coil (104) and arranged to conduct current in the second direction; a second outer coil (212) located radially outward of the second inner coil (105) and arranged to conduct current in the first direction; The magnetic mirror device (200) further comprises:

2. A nuclear fusion reactor comprising a magnetic mirror device (200) according to claim 1.

3. Use of a magnetic mirror device (200) according to claim 1 for confining a plasma.

4. Use of the magnetic mirror device (200) according to claim 1 in a nuclear fusion reactor.

5. A method of operating a magnetic mirror device (200), comprising: a first inner coil (104) of the magnetic mirror device that conducts current in a first direction; a second inner coil (105) of the magnetic mirror device axially offset from the first inner coil and conducting current in a second direction opposite to the first direction; a first outer coil (210) of the magnetic mirror device located radially outward of the first inner coil (104) and conducting current in the second direction; a second outer coil (212) of the magnetic mirror device located radially outside the second inner coil (105) and conducting current in the first direction; A method comprising:

6. The method of claim 5 , wherein the method is performed to confine a plasma.

7. 7. The method of claim 5 or 6, wherein the method is carried out in a nuclear fusion reactor.

Images