TARGET FOR TRIGGERING NUCLEAR FUSION REACTIONS NON-THERMALLY, SYSTEM AND METHOD FOR PRODUCING FUSION ENERGY

Abstract

A target (10) for triggering nuclear fusion reactions non-thermally includes a plurality of aligned nano-rods (12) of a first nuclear fusion fuel material, and an interspace between the nano-rods filled with a second nuclear fusion fuel material. The first and second nuclear fusion fuel materials are different from each other. In some embodiments, the nuclei of the first nuclear fusion fuel material have a first atomic number and nuclei of the second nuclear fusion fuel material have a second atomic number, wherein the first atomic number is higher than the second atomic number. A system for producing neutronic and aneutronic fusion energy by a neutronic and/or aneutronic nuclear fusion reaction includes a target (10) and a laser device for emitting a laser pulse that can at least partially be absorbed by the target (10).

Claims

1. A target for triggering nuclear fusion reactions non-thermally, the target comprising: a plurality of aligned nano-rods of a first nuclear fusion fuel material, and an interspace between the nano-rods filled with a second nuclear fusion fuel material, wherein the first and second nuclear fusion fuel materials are different from each other.

2. The target according to claim 1, wherein a portion or all of the nano-rods of the target are cylindrically or conically shaped while having a circular, elliptical, rectangular, or polygonal base, each having a rod-diameter and a rod-length.

3. The target according to claim 1, wherein nuclei of the first nuclear fusion fuel material have a first atomic number and nuclei of the second nuclear fusion fuel material have a second atomic number, wherein the first atomic number is higher than the second atomic number.

4. The target according to claim 1, wherein the first nuclear fusion fuel material comprises boron and/or lithium.

5. The target according to claim 1, wherein the second nuclear fusion fuel material comprises tritium and/or deuterium.

6. The target according to claim 1, wherein the first nuclear fusion fuel material is doped with a further nuclear fusion constituent.

7. The target according to claim 1, wherein the plurality of aligned nano-rods comprises nano-rods of different first nuclear fusion fuel materials which are interlaced.

8. A system for producing neutronic and aneutronic fusion energy by a neutronic and/or aneutronic nuclear fusion reaction, the system comprising: a target according to claim 1, and a laser device for emitting a laser pulse, wherein the laser pulse can at least partially be absorbed by the target.

9. The system according to claim 8, wherein the laser pulse is a femtosecond optical to vacuum ultraviolet (VUV) laser pulse.

10. A method for producing neutronic and aneutronic fusion energy by a neutronic and/or aneutronic nuclear fusion reaction, the method comprising irradiating a target according to claim 1 with a laser pulse, wherein the laser pulse is at least partially absorbed by the target.

11. The method according to claim 10, wherein the laser pulse is a femtosecond optical to vacuum ultraviolet (VUV) laser pulse.

12. The target according to claim 2, wherein the rod-diameter is 100 nm or smaller.

13. The method according to claim 12, wherein the rod-diameter is 50 nm or smaller.

14. The method according to claim 12, wherein the rod-diameter is 30 nm or smaller.

15. The method according to claim 2, wherein the rod-length is above 10 μm.

16. The method according to claim 15, wherein the rod-length is between 10 μm and 100 μm.

17. The method according to claim 15, wherein the rod-length is between 10 and 300 μm.

18. The target according to claim 4, wherein the first nuclear fusion fuel material comprises p.sup.11B, p.sup.6Li, .sup.2D.sup.6Li, n.sup.6Li, and/or n.sup.7Li reactions.

19. The target according to claim 6, wherein the boron is doped with p, D and/or Li, and the Li is doped with p.

20. The target according to claim 7, wherein the plurality of aligned nano-rods comprises nano-rods of B and Li which are interlaced.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0079] FIG. 1 illustrates a perspective view of a preferred target.

[0080] FIGS. 2a and 2b illustrate a top view of the preferred target of FIG. 1.

[0081] FIG. 3 illustrates a side view of the preferred target of FIG. 1.

[0082] FIG. 4 shows the conversion fraction η.sup.pB as a function of β.sup.pB and n.sub.BR.sub.p.

[0083] FIG. 5 is an exemplary isocontour plot illustrating the scaling behavior of the conversion efficiency Q.sup.pB.

[0084] FIG. 6 shows the conversion fraction η.sup.DT as a function of β.sup.DT and n.sub.TR.sub.D.

[0085] FIG. 7 is an exemplary isocontour plot illustrating the scaling behavior of the conversion efficiency Q.sup.DT.

DETAILED DESCRIPTION

[0086] In the following detailed description, same or corresponding elements and features are referenced by the same or corresponding reference signs and a repetitive description thereof is avoided.

[0087] FIG. 1 illustrates a perspective view of a preferred target 10. A common base 14 is, in the illustrated embodiment, square shaped and has a flat upper surface 15 from which a plurality of nano-rods 12 extend perpendicularly from the common base 14. The nano-rods 12 are regularly arranged along a first direction X and a second direction Y, wherein the first direction X and the second direction Y are perpendicularly oriented with respect to each other in a Cartesian sense. Alternative arrangements of perpendicular directions are, for example, according to circular coordinates, i.e., along a radius with respect to an origin, and a circumference about this origin.

[0088] FIGS. 2a and 2b illustrate a top view of the preferred target 10 of FIG. 1, wherein FIG. 2a illustrates a total top view of the target 10, and FIG. 2b a detailed view of the illustration of FIG. 2a, namely, the top right corner including four of the nano-rods 12 illustrated in FIG. 2a. The top view of FIG. 2a more clearly illustrates that the nano-rods 12 are regularly, in this embodiment periodically, arranged along the first and second directions X and Y. FIG. 2a also illustrates a first target side length D and a second target side length D′. As illustrated, it is preferred that the nano-rods 12 are regularly arranged over the total of the first and second target side lengths D and D′. FIG. 2b highlights that a first rod-distance B between adjacent nano-rods in the first direction X is equal to a second rod-distance B′ between adjacent nano-rods in the second direction Y. Although the first and second rod-distances B, B′ can differ from each other, it is preferred that the first rod-distance B is the same as the second rod-distance B′ for at least 50% of the nano-rods 12 of the target 10, further preferably for at least 90% of the nano-rods 12 of the target 10. A rod-diameter A is smaller than the first and second rod-distances B, B′.

[0089] FIG. 3 illustrates a side view of the preferred target 10 of FIG. 1. In this side view according to FIG. 3, the nano-rods 12 are shown to have a rod-length C which is measured perpendicularly to the surface 15 of the common base 14 and between the surface 15 and a top base 16 of the nano-rods 12. The nano-rods 12 illustrated here are straight cylinders but can also be non-cylindrically shaped or oblique cylinders or hollow cylinders. However, the illustrated shape of the nano-rods is preferred.

[0090] The first and second target side lengths D and D′ of the target 10 can preferably be determined by a size of a focal spot of the laser used for the ignition, and the necessary amount of material around it to get gain well above one. As the nano-structured material has areal scaling properties, increasing D and D′ and the focal spot of the laser also increases the total fusion yield. Another parameter for variation is the composition of the target material as described before.

[0091] A system for ignition of a non-thermal fusion reaction also comprises a laser device, which is not illustrated, and which is configured for emitting a laser pulse, wherein the laser pulse has a laser carrier frequency ω, a pulse duration, and a spot size, and which can at least partially be absorbed by the nano-structured material of the target 10. An intensity of the laser pulses measured in W/cm.sup.2 can be varied through increasing the pulse energy, the pulse length or the focus spot size of the laser device. Further, the wavelength of the laser pulse can be varied.

[0092] It is preferred that the target 10 and laser properties are aligned. According to the fundamental scaling behavior of the target 10, fusion yield significantly increases with shorter wavelength. Hence, preferably, the first rod-distance B and the second rod-distance B′ of the target 10 is greater than or equals √{square root over (R.sup.2n.sub.ie.sup.2/4π∈.sub.0m.sub.eω.sup.2)}, wherein R is the radius of the rod, n.sub.i is the average ion density, e is the charge of an electron, so is the electric field constant, m.sub.e is the electron mass, and ω is the laser carrier frequency.

[0093] The intensity of the laser, including its focal spot, then determines the optimum diameter of the nano-rods. The rod length is determined by how far the laser can propagate into the target until it has fully depleted its energy. In the following, Examples of preferred technical parameters for the system of the laser device and target 10 are shown:

Example 1

[0094] Laser system:

TABLE-US-00001 Wavelength 210 nm Intensity 10.sup.21 W/cm.sup.2

[0095] Nano-rods 12 of target 10:

TABLE-US-00002 Rod-diameter A 30 nm Rod-length C 10-300 μm First rod-distance B 200 nm (center to center) Second rod-distance B′ 200 nm (center to center)

Example 2

[0096] Laser system:

TABLE-US-00003 Wavelength 400 nm Intensity 10.sup.21 W/cm.sup.2

[0097] Nano-rods 12 of target 10:

TABLE-US-00004 Rod-diameter A 30 nm Rod-length C 10-300 μm First rod-distance B 400 nm (center to center) Second rod-distance B′ 400 nm (center to center)

[0098] FIGS. 4 and 6 are exemplary graphs illustrating conversion fractions. FIG. 4 illustrates the conversion fraction η.sup.pB as a function of β.sup.pB and n.sub.BR.sub.p. FIG. 6 illustrates the conversion fraction η.sup.DT as a function of β.sup.DT and n.sub.TR.sub.D.

[0099] FIGS. 5 and 7 are exemplary isocontour plots illustrating Q of the fusion energy yield and in particular the scaling behavior of Q normalized to the initial energy in the ionic distributions after laser energy deposition of preferred non-thermal pB and DT fusion reactions as a function of β.sup.pB and β.sup.DT as well as n.sub.BR.sub.p and n.sub.TR.sub.D, respectively.

[0100] FIG. 5 illustrates the effective Q.sup.pB as a function of β.sup.pB and n.sub.BR.sub.p. With increasing n.sub.BR.sub.p the parameter β.sup.pB has to grow for best Q.sup.pB. Large β.sup.pB, however, imply a smaller conversion fraction η.sup.pB.

[0101] The conversion efficiency Q.sup.DT as a function of β.sup.DT and n.sub.TR.sub.D is shown in FIG. 7. With increasing n.sub.TR.sub.D the parameter β.sup.DT has to grow for best Q.sup.DT. Large β.sup.DT however, imply smaller η.sup.DT.

LIST OF REFERENCE SIGNS

[0102] 10 target [0103] 12 nano-rod [0104] 14 common base [0105] 15 surface [0106] 16 top base [0107] A rod-diameter [0108] B first rod-distance [0109] B′ second rod-distance [0110] C rod-length [0111] D first target side length [0112] D′ second target side length [0113] X first direction [0114] Y second direction

[0115] The various embodiments described above can be combined to provide further embodiments. All of the U.S. patents, U.S. patent application publications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet are incorporated herein by reference, in their entirety. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications, and publications to provide yet further embodiments.

[0116] These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled.