Arrangement and method for exciting a laser-based fusion reaction in a fusion target
Patent Information
- Application Number
- PCT/DE2026/100172
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-02-19
- Filing Date
- 2026-02-13
- Publication Date
- 2026-08-27
Smart Images
Figure DE2026100172_27082026_PF_FP_ABST
Abstract
Description
[0001] ARRANGEMENT AND METHOD FOR INITIATING A LASER-BASED FUSION REACTION IN A FUSIONSTARGET
[0002] The invention relates to an arrangement and a method for exciting a laser-based fusion reaction.
[0003] Various technologies for converting nuclear energy into thermal and ultimately electrical energy by means of nuclear fusion are already known in the prior art, whereby a fundamental distinction can be made between technologies based on magnetic confinement and technologies based on inertial confinement.
[0004] 1. Magnetic confinement
[0005] In magnetic confinement, the fusion reaction in a plasma (usually using deuterium and tritium) is initiated by extremely high temperatures exceeding 100 million degrees at relatively low pressures. This requires a long confinement time for the plasma, for which two fundamental concepts exist: the tokamak and the stellarator. These devices employ sometimes complex magnetic fields to confine and heat the plasma long enough for fusion reactions to occur, ideally yielding more energy than is consumed.
[0006] The best-known example of a tokamak is the international fusion reactor ITER (Cadarache, France), which is intended to achieve a positive energy balance for the first time using magnetic confinement.
[0007] A well-known example of a stellarator is Wendelstein-7X (Greifswald, Germany), which, however, is not yet designed for a positive energy balance and primarily serves to research the technology.
[0008] Magnetic confinement technology is extremely complex and expensive, and remains the subject of intensive research worldwide. A fundamental disadvantage of this technology is that extremely high temperatures must be achieved due to the low pressure in the plasma chamber. Because of these high temperatures, the plasma must be kept permanently away from the reactor wall, requiring extremely sophisticated and powerful magnetic fields.
[0009] 2. Inertial confinement
[0010] An alternative technology is inertial confinement. This involves attempting to initiate fusion reactions by extremely compressing fuel spheres (so-called targets) made of ignitable material (usually deuterium and tritium, but also hydrogen and boron) in a very short time, thereby achieving very high pressures and temperatures. The compression of the targets can be achieved using various methods, such as particle beams or even light (laser beams). However, it has been shown that compression using particle beams requires a significant effort to accelerate the particles.
[0011] Intensive research is currently being conducted on laser inertial confinement technology, as increasingly powerful lasers are being developed. For example, in 2022, the Lawrence Livermore National Laboratory (LLNL) in the USA announced that, for the first time, more energy was released through fusion at its National Ignition Facility (NIF) than was used to compress the targets. However, the energy balance remains extremely negative, as this calculation does not include the energy required to generate the laser pulses.
[0012] There are various concepts for inertial confinement using lasers. Most often, the fusion target is irradiated in a reactor chamber with a multitude of laser beams from different directions, either directly or indirectly, with the lasers being precisely aligned before the system is operated.
[0013] a. Direct Drive
[0014] In this technique, the target is bombarded from all sides with laser beams, which compresses and heats it. Due to the direct irradiation, this technique is highly efficient. However, the high demands on the laser's accuracy, timing, and the target's shape prove to be disadvantages.
[0015] b. Indirect Drive (concept of NIF)
[0016] In this technique, a cavity containing the target is heated using laser radiation. The cavity emits X-rays that heat the target. The advantage of this technique is that the requirements for laser accuracy are relatively low. However, a disadvantage is the lower efficiency compared to direct laser irradiation of the target.
[0017] c. Fast Ignition
[0018] In this technique, compression and ignition occur separately. The target is first compressed by an initial laser irradiation, and ignition is triggered by a subsequent second laser irradiation. A disadvantage of this method is that the penetration of the ignition laser into the center of the target is hampered by "dirt" from the previous compression.
[0019] d. Shock Ignition
[0020] In this process, the target is first compressed, but this time not by laser irradiation, but by means of shock waves. In a subsequent step, the actual ignition of the target then takes place.
[0021] A particularly promising concept is the ignition method described in section a., using direct drive, in which the target is bombarded directly and simultaneously with lasers from all sides. This is intended to achieve uniform compression of the target, generating very high pressures and temperatures within it, thus initiating the fusion reaction. The targets are on the order of a few millimeters in size. For continuous energy generation, it is necessary to ignite a large number of targets sequentially. Concepts for this already exist, involving the insertion of targets into a reactor chamber. The targets are then bombarded with laser beams from various directions in the center of the reactor chamber. The lasers are precisely aligned before the system is put into operation.
[0022] However, several technical challenges must be overcome in this context. For successful nuclear fusion, it is crucial that the laser beams strike the target uniformly and simultaneously from all sides. This means that the laser beams must be aligned so that the focus of each individual beam lies on the target's surface. Furthermore, the multitude of laser foci must be evenly distributed across the target's surface, and the beams must strike the target at precisely the same time to achieve uniform and simultaneous compression. If a laser pulse deviates even slightly from the ideal position or arrives late, the fuel in the target can shift at that point, preventing effective compression.
[0023] Furthermore, it should be noted that the target may deviate from an ideal spherical shape due to manufacturing tolerances or deformation during insertion into the reactor chamber. This results in uneven compression of the target, leading to plasma instabilities (so-called Raleigh-Taylor instabilities) and consequently preventing the necessary ignition threshold from being reached or resulting in only a small portion of the fuel being fused.
[0024] The present invention is based on the objective of providing an arrangement and a method for exciting a laser-based fusion reaction, whereby a uniform and simultaneous irradiation of the moving fusion target from all sides by a plurality of laser beams with high dynamics is made possible.
[0025] A further object of the present invention is to provide an alternative arrangement and an alternative method for exciting a laser-based fusion reaction. The present invention solves the aforementioned problems in an arrangement for exciting a laser-based fusion reaction, comprising:
[0026] a reactor chamber with an inlet for injecting fusion targets, a device for generating a plurality of laser beams for direct bombardment of the fusion target, wherein the direction of the laser beams is adjustable by means of a mirror device with at least one tilting mirror adjustable in at least one spatial direction,
[0027] a measuring system that is set up to record measurement data of the fusion target within the reactor chamber, and
[0028] a control unit that is set up to receive measurement data of the fusion target from the measuring system and, depending on the received measurement data, to adjust or adapt the tilting mirrors of the mirror devices in a manner individually adapted to the respective fusion target.
[0029] Furthermore, the present invention solves the aforementioned problems in a method for exciting a laser-based fusion reaction, comprising:
[0030] Injecting a fusion target into a reactor chamber;
[0031] Providing a device for generating a plurality of laser beams for direct bombardment of the fusion target, wherein the direction of the laser beams is adjusted by means of a mirror device with at least one tilting mirror adjustable in at least one spatial direction;
[0032] Acquisition of measurement data from the fusion target within the reactor chamber using a measurement system; and
[0033] Tracking or adjusting the tilting mirrors of the mirror devices in a manner individually adapted to the respective fusion target, depending on the measurement data of the fusion target recorded by the measuring system.
[0034] The term "fusion target" is to be understood in the broadest sense and generally refers to a spatially confined fuel sphere made of fusion-capable material, such as deuterium and tritium (DT), hydrogen and boron, etc. Although the fusion target generally contains the fuel in solid form, fusion targets with liquid or gaseous fuel are also fundamentally possible. The present invention provides an approach to nuclear fusion using distributed lasers deflected by mirror devices for the direct bombardment of a fusion target. The fusion target is bombarded simultaneously from different sides by several laser beams, the laser beams being controllable in at least one axis by tilting mirrors in order to track the fusion target with high dynamics. According to one embodiment of the invention, the laser beams are individually oriented and, if necessary,The laser beams are additionally adjusted in intensity, timing, or arrangement on the target surface to ensure ideal combustion of the fusion target's fuel. The laser beams are aligned by a control unit based on measurement data acquired by an upstream measuring system for the respective fusion target. Thus, the laser beam alignment can be dynamically adapted to the specific properties of each fusion target. In this way, a uniform distribution of the numerous laser focuses across the surface of the fusion target can be achieved with high accuracy, resulting in uniform compression.
[0035] The measurement system for determining measurement data of the fusion target can be designed as a passive system, comprising, for example, one or more cameras, which captures the measurement data of the fusion target without further aids in the form of simple optical images and transmits these to the control unit. The measurement system could also be designed as an active system, in which, for example, the fusion target is scanned using electromagnetic radiation. Such an active configuration can be implemented as an alternative to or in addition to the aforementioned cameras. When scanning the fusion target using electromagnetic radiation, the radiation reflected, scattered, or otherwise affected by the fusion target can be detected by a receiving device, and measurement data about the fusion target can be derived from this data and then transmitted to the control unit.For irradiating the fusion target, for example, (visible) laser radiation or X-rays can be used. In one embodiment, the measurement data is evaluated using interferometric methods. Here, for example, interference patterns arising from the superposition of coherent or partially coherent waves can be analyzed. Interferometry allows, in particular, the determination of phase shifts, optical path length changes, refractive index distributions, or surface profiles with high accuracy. Alternatively or additionally, shadowgraphy methods, phase contrast methods, and / or other imaging evaluation techniques can be used. It is understood that the aforementioned methods can be used individually or in any combination.It is also possible to apply several evaluation methods in parallel or sequentially to increase the accuracy, robustness, or information density of the measurement data evaluation.
[0036] For a fusion reaction to begin, the compression must be such that an inward-directed shock front is generated. With an ideally spherical fusion target, this means that the laser beams are directed evenly distributed across the surface in a specific grid pattern. Furthermore, the energy input must be simultaneous. The energy of each laser pulse must also be the same to achieve uniform compression. Deviations from this (such as deviations from a spherical shape, a delayed pulse, or a pulse with too little or too much energy) can cause the target to deflect at that point, resulting in a failure to fusion or only a small portion of the target's fuel being fused. The arrangement proposed according to the invention...The method proposed according to the invention addresses this problem by dynamically adapting the orientation of the laser beams to the specific properties of each fusion target. In this context, the term "uniform" is to be understood as meaning that the irradiation of the target is individually adapted to its properties (e.g., position, velocity, shape, rotation, and / or the like), so that an inwardly directed optimal compression of the target is achieved, thus triggering a fusion reaction. According to an advantageous embodiment of the invention, the measurement data acquired by the measuring system include position data and / or velocity data of the fusion target. In other words, the measuring system determines the position and velocity of the target, ultimately an exact flight or motion vector of the fusion target.Based on this information, the ideal firing parameters for the individual laser beams are determined, in particular their individual alignment. Should the target, for example due to deviations in its position or trajectory, not be in focus of the lasers, the laser beams are dynamically adjusted depending on the corresponding measurement data.
[0037] According to an advantageous embodiment of the invention, the at least one tilting mirror of the mirror assembly is adjustable in two spatial directions. This enables particularly flexible and highly accurate adjustment of the laser beam alignment to the respective fusion target.
[0038] The laser beams can be generated in various ways within the scope of the present invention. For example, the arrangement can have only a small number of laser sources, with the generated beams being split into several individual beams, which are then directed into the reactor chamber via mirrors. A mirror device is located in the beam path of each individual beam, directing the beam precisely onto the fusion target. In the extreme case, all individual beams could be generated in this way using a single laser source. Alternatively, the arrangement could have a multitude of laser sources, such that each individual laser beam is generated by a separate laser source. It should be noted that, in principle, many individual, lower-powered laser sources are simpler and more cost-effective to implement than one large, high-powered laser source.Furthermore, the energy densities on the mirrors of the mirror devices used to align the individual laser beams decrease significantly when multiple laser beams are used.
[0039] According to an advantageous embodiment of the invention, the measuring system is further configured to determine the shape of the surface of the fusion target, wherein the control unit is configured to receive data regarding the shape of the surface of the fusion target from the measuring system and, based on this data, to adjust the tracking or adjustment of the tilting mirrors of the mirror devices for uniform irradiation of the fusion target by the majority of laser beams. Knowledge of the exact geometry of the fusion target offers the advantage that the bombardment parameters for the laser beams can be adjusted accordingly to achieve uniform coverage of the surface of the fusion target with the energy of the laser beams. For example, if the measuring system is used to determine the shape of the surface of the fusion target, the control unit can adjust the tracking or adjustment of the tilting mirrors of the mirror devices to ensure uniform irradiation of the fusion target by the majority of laser beams.If the fusion target has a perfectly spherical surface, the laser beams can be evenly distributed across the surface using the control unit, and the same intensity / energy output can be set for all laser beams. If, however, the measuring system detects a deviation of the fusion target's geometry from a perfect sphere, the control unit can, for example, selectively align individual laser beams with surface deformations, so that the radiation output (energy) is directed evenly onto the fuel inside the fusion target.
[0040] The surface shape of the target can deviate from an ideal spherical shape due to manufacturing tolerances during production. Subsequent influences (such as during storage or transport) can also cause deviations. Finally, the target's shape can be altered by the forces exerted when it is inserted into the reactor chamber. These deviations can manifest as individual defects (dents, bumps, or similar) on the surface, or as general deviations from a spherical shape, such as deformation of the target towards ellipsoids or other similar deviations from a spherical form.
[0041] According to an advantageous embodiment of the invention, the measuring system is further configured to determine the rotational speed and direction of rotation of the fusion target. Knowledge of these parameters, in conjunction with knowledge of the position, speed, and direction of movement of the fusion target, offers the advantage that the precise position or orientation of any surface deformation at the desired time of laser irradiation of the fusion target can be predetermined, and the alignment of the individual laser beams can be adjusted or adapted accordingly in advance using the control device.
[0042] According to an advantageous embodiment of the invention, the measuring system is designed as an optical measuring system with a plurality of optical sensors. The optical sensors can, for example, include cameras (in particular, for example, line scan cameras and / or matrix cameras) and can be configured to acquire measurement data from different directions at different times in order to determine parameters such as the exact flight vector, the exact position in space, the exact geometry, and, if applicable, the intrinsic rotation speed and direction of rotation of the fusion target. With a view to achieving the highest possible precision of the measurements, the exposure times for the individual measurements can be selected to be correspondingly short. Additionally or alternatively, the optical sensors of the measuring system can be provided with an active image stabilization device. This image stabilization can, for example, be implemented in the form of a Fast Steering Mirror (FSM).
[0043] According to an advantageous embodiment of the invention, the measuring system comprises a plurality of temperature sensors distributed on the inside of the reactor wall. As already mentioned, the trajectory of the fusion target runs through the vacuum of the reactor chamber. Thus, a change in the trajectory of the fusion target due to friction / collision with other molecules is largely excluded. However, there is a possibility that the trajectory and / or the geometry of the fusion target may be influenced after measurement by the optical sensors of the measuring system due to the radiant heat from the reactor wall. For example, the fusion target could melt slightly and thus change its shape.The temperature sensors enable the measurement of radiant heat and the counteracting of the aforementioned effect by using the temperature sensor data to consider the effects of radiant heat on the geometry and trajectory of the fusion target and, if necessary, to adjust the laser beam orientation via the control unit. According to an advantageous embodiment of the invention, the tilting mirrors of the mirror devices are designed as Fast Steering Mirrors (FSMs – alternatively often also referred to as Fine Steering Mirrors). This design enables high dynamics of the mirror device, allowing for individual beam direction with individual target coordinates for each laser beam. The specific construction of the FSMs can correspond to the structure described in DE 102021 202 120 A1 – the disclosure of which is hereby incorporated into the present application by reference.
[0044] According to an advantageous embodiment of the invention, the FSM comprises means for dissipating heat from the tilting mirror. In this context, it must be considered that the mirror of the FSM heats up due to the high incident laser power, making the thermal management of the beam system particularly important. If the FSM is partially arranged in the reactor chamber, the mirror or the internal components of the FSM are also heated, in particular by radiant heat from the reactor wall or by heat from the reaction. To prevent damage to the mirror or the components behind it from heat input, the heat must be dissipated efficiently. This can be achieved, for example, by means of specific heat-dissipating elements that are installed in or on the FSM. Alternatively or additionally, existing components of the FSM can be used for heat dissipation. For example, heat dissipation can occur via the solid-state hinge of the FSM.In its installed state, the solid-state joint of the FSM connects the movable mirror to the reactor wall, whereby the connection can be realized mechanically in various ways. As an alternative to a direct connection, it is conceivable, for example, that the solid-state joint is connected to a housing of the FSM, the housing being part of the reactor wall. According to an advantageous embodiment of the invention, the solid-state joint can be designed as part of a cooling system. Specifically, cooling channels can be formed inside the solid-state joint, through which a cooling fluid flows. Alternatively or additionally, the solid-state joint could be made of a material with particularly high thermal conductivity. This allows the heat to be efficiently dissipated from the mirror of the FSM. According to an advantageous embodiment of the invention, the FSM is integrated into the reactor wall of the reactor chamber, forming a vacuum barrier.It is possible to arrange passive elements of the FSM inside and active elements outside the reactor chamber. Specifically, for example, the tilting mirror and the mirror suspension, including the solid-state hinge, can be located inside the reactor chamber, while the sensors and actuators for aligning the tilting mirror, including the associated electronics, can be located outside the reactor chamber. In this case, the detection of the position and velocity of the fusion target by the measuring system, as well as the actuation (= alignment) of the laser beams across the vacuum barrier, can also take place outside the reactor chamber. In a particularly advantageous embodiment, parts of the sensor system or...The actuators of the FSM serve to separate the reactor chamber, whereby an arrangement corresponding to the actuator-sensor arrangement disclosed in EP 3063504 B1 – the disclosure of which is hereby incorporated into the present application by reference – can be implemented. In particular, parts of the sensor or actuator system can, for example, be designed as a component of the reactor wall or be embedded in the reactor wall and thus realize the vacuum barrier.
[0045] According to an alternative embodiment, the tilting mirrors of the mirror devices are arranged outside the reactor chamber, and the laser beams can be directed into the reactor chamber through feedthroughs formed in the reactor wall. Beam alignment thus takes place outside the vacuum of the reactor chamber. The feedthroughs formed in the reactor wall can be, for example, inlet windows or fibers. Inlet windows are advantageously made of a material with a high transmission coefficient for the respective frequency of the laser radiation used, so that the aligned laser beams can be directed into the reactor chamber with minimal loss.
[0046] According to an advantageous embodiment of the invention, the spot diameter and the number of laser beams are dimensioned such that the superposition of the individual distribution functions of the individual laser beams results in a uniform power density on the surface of the fusion target. In this context, starting from a Gaussian beam profile of the laser beams, it can be provided, for example, that any two target points of adjacent laser beams on the surface of the fusion target have a maximum distance from each other, which is defined by the extent of the beam profile on the target surface at which the laser intensity in the Gaussian profile has dropped to 1 / e of the maximum intensity at the center of the beam profile. However, if the surface shape of the target deviates more significantly from a spherical shape, e.g.,If the surface is dented or raised, the spacing of the target points may need to be adjusted to account for the surface shape and achieve uniform compression of the target. For example, if the surface is raised, the spacing of the target points must be reduced to achieve the necessary power density for compression due to the accumulation of fuel at that point.
[0047] According to an advantageous embodiment of the invention, the laser beams are generated by a plurality of individual laser sources, which are synchronized together. This offers the advantage that no expensive high-power laser is required, but rather the energy input necessary to excite / ignite a fusion reaction can be supplied by the sum of numerous relatively lower-power laser sources. In addition to the lower costs, the comparatively lower power input on the surfaces of the mirrors used to align the laser beams is also a benefit.
[0048] According to an advantageous embodiment of the invention, compression of the fusion target is triggered by a pre-irradiation comprising at least one generation of a plurality of laser beams, and ignition of the fuel in the compressed fusion target is triggered by a subsequent irradiation comprising at least one generation of a plurality of laser beams. In other words, the fusion target is repeatedly struck by the laser beams to separate the compression process from the ignition process. According to an advantageous embodiment of the invention, the method, in particular, for example, the calculation of the orientation of the individual laser beams, i.e., the calculation of the laser trajectories, is carried out in a self-learning feedback loop to obtain the optimal energy yield in the fusion reaction. The feedback loop can be supported by AI.Specifically, the method can involve measuring the fusion energy yield generated during the fusion reaction. Based on these measurements, the tracking or adjustment of the tilting mirrors of the mirror devices can be optimized using the self-learning feedback loop and the measured fusion energy yield as a target optimization parameter.
[0049] There are now various ways to advantageously elaborate and further develop the teaching of the present invention. For this purpose, reference should be made, on the one hand, to the claims subordinate to independent claims 1 and 14, and on the other hand, to the following explanation of preferred embodiments of the invention with reference to the drawing. In conjunction with the explanation of the preferred embodiments of the invention with reference to the drawing, generally preferred embodiments and further developments of the teaching are also explained. The drawing shows
[0050] Fig. 1 shows a schematic representation of the temporal sequence of mirror alignment in a mirror device of an arrangement for exciting a laser-based fusion reaction according to an embodiment of the present invention.
[0051] Fig. 2 shows a schematic representation of the temporal sequence according to Figure 1 in an arrangement with a plurality of mirror devices according to an embodiment of the present invention.
[0052] Fig. 3 shows a schematic representation of an arrangement for exciting a laser-based fusion reaction according to an embodiment of the present invention, wherein the mirror devices are arranged outside the reactor chamber. Fig. 4 shows a schematic representation of an arrangement for exciting a laser-based fusion reaction according to an embodiment of the present invention, wherein the mirror devices are partially arranged inside the reactor chamber.
[0053] Fig. 5 shows a spatial schematic representation of an arrangement for exciting a laser-based fusion reaction according to an embodiment of the present invention with a plurality of laser sources.
[0054] Fig. 6 shows an enlarged schematic representation of a laser source of the arrangement according to Fig. 5 together with associated mirror device,
[0055] Fig. 7 shows a schematic representation of target points of laser beams on the surface of a fusion target in an arrangement for exciting a laser-based fusion reaction according to an embodiment of the present invention.
[0056] Fig. 8 shows a schematic representation of a mirror arrangement partially located within the reactor chamber of an arrangement for exciting a laser-based fusion reaction according to an embodiment of the present invention, and
[0057] Fig. 9 shows a schematic representation of target points of laser beams on the surface of a deformed fusion target in an arrangement for exciting a laser-based fusion reaction according to an embodiment of the present invention.
[0058] The figures illustrate the features of the invention only in principle and do not claim to be physically accurate. In particular, laser beams are generally only depicted in principle and do not correspond to (geometric) optics. In the arrangement according to the invention for exciting a laser-based fusion reaction, each individual laser source of the arrangement is assigned a mirror device for aligning the respective laser beam. The mirror device comprises at least one tilting mirror adjustable in two spatial directions and optionally additional reflective components, in particular, for example, one or more deflecting mirrors.
[0059] Fig. 1 schematically shows an exemplary mirror designed as an FSM (Fast Steering Mirror) 2 as a component of such a mirror device 1. The FSM 2 comprises a tilting mirror 3 adjustable in two spatial directions and a sensor and actuator unit 4 for precise adjustment of the orientation of the tilting mirror 3.
[0060] Fig. 1 illustrates, step by step, the temporal sequence of the alignment of the tilting mirror 3 and the fuel ignition using the FSM 2 shown as an example. As described in detail below, according to an exemplary embodiment, based on information from a measuring system 19 for determining the geometry and trajectory of the fusion target 5 in the reactor chamber 6 (not shown in Fig. 1), an individual trajectory of the fusion target 5 is calculated for each target and / or each fusion cycle. The FSM 2 is then controlled so that the respective laser beam strikes the surface of the fusion target 5 at the desired location. This is done synchronously for all laser sources of the arrangement.
[0061] With regard to the control of the FSM 2, it is specifically intended that the tilt angle of the tilting mirror 3 adapts dynamically in such a way that a specific, predetermined position on the fusion target 5 is directly targeted when an imaginary laser line is projected. If the fusion target 5 is in a specific, predetermined position, the laser sources are activated and laser beams are emitted. Immediately after the laser beams strike the fusion target 5, compression of the fusion target 5 occurs, and—provided the irradiation of the fusion target 5 is sufficiently uniform and simultaneous—the fuel is ignited in the next step, thereby initiating the nuclear fusion reaction.
[0062] In Fig. 2, the same process is depicted in the diagrams from left to right, using multiple FSMs 2. Fig. 2 is a sectional view showing only one plane with a total of 6 FSMs 2 arranged in this plane. In a three-dimensional view, the irradiation arrangement is ideally designed such that the FSMs are evenly distributed in the space around the reactor chamber 6 (not shown in Fig. 2), so that the entire surface of the fusion target 5 is irradiated uniformly.
[0063] Fig. 3 shows a schematic representation of an arrangement for exciting a laser-based fusion reaction according to an embodiment of the present invention, with a plurality of laser sources 7 arranged around the reactor chamber 6. This is again a sectional view, showing only one plane of the irradiation arrangement. In a real implementation, the individual laser sources 7, together with their respective associated mirror arrangement 1, are uniformly distributed in the space around the reactor chamber 6, as shown by way of example in Fig. 5.
[0064] Fig. 3 shows a spherically shaped reactor chamber 6 with an inlet 8 for injecting fusion targets 5. A vacuum prevails inside the reactor chamber 6. The introduction of fusion targets 5 into the reactor chamber 6 can be carried out using conventional injection methods, as are known from the prior art. The production of the fusion targets 5 can also be carried out using conventional fuel generators, which are likewise known from the prior art.
[0065] As shown in the arrangement for exciting a laser-based fusion reaction according to Fig. 3, the arrangement includes a measuring system 19 configured to acquire measurement data of a fusion target 5 within the reactor chamber 6. For this purpose, the measuring system 19 can include several cameras 20 that measure the target 5 from different directions and at different times. In the arrangement according to Fig. 3, two cameras 20 are provided by way of example, arranged opposite each other at the inlet channel of the reactor chamber 6. However, it is understood that the measuring system 19 can include more than two cameras, which can also be positioned differently than in Fig. 3. In particular, cameras can be oriented towards the space within the reactor chamber 6 such that the fusion target 5 is measured along its entire path through the reactor chamber 6, i.e.,The process from inlet 8 to ignition in the center of reactor chamber 6 can be observed, and measurement data from the fusion target 5 can be recorded. To ensure high measurement precision, the cameras 20 advantageously feature image stabilization. For example, each camera 20 could have an FSM for image stabilization.
[0066] Measurement data is determined from the camera recordings, which, for example, represent one or more of the following parameters of Fusion Target 5:
[0067] - Position of fusion target 5 in space at a specific time. - Velocity and motion vector of fusion target 5. - Geometry of fusion target 5: In this respect, deviations from an ideal spherical shape are particularly important, which can arise, for example, due to manufacturing tolerances or deformation during insertion into reactor chamber 6.
[0068] - Rotation speed and rotation direction of the fusion target 5.
[0069] From these parameters, the exact location and orientation of the fusion target 5 at the desired time of laser activation are calculated. Additionally, the shape of the surface of the fusion target 5 is determined from these parameters. Based on this, the precise trajectories for the FSMs 2 of the mirror arrangements 1 of the laser sources 7, as well as the exact target points on the surface of the fusion target 5, are then determined.
[0070] In the embodiment shown in Fig. 3, the mirror arrangements 1 assigned to each of the individual laser sources 7 include, in addition to the FSM 2, a deflecting mirror 9. The beam guidance is such that the laser sources 7 are aligned towards the reactor chamber 6 and the laser beams are reflected onto the FSM 2 by means of the deflecting mirrors 9. To couple a laser beam into the reactor chamber, the tilting mirror 3 of the FSM 2 then reflects the respective laser beam onto an inlet window 10 arranged in the reactor wall of the reactor chamber 6. The laser beam is thereby directed precisely onto the fusion target 5, as will be described further and in detail. The inlet windows 10 are made of a material that has a high transmission coefficient for the respective frequency of the laser radiation from the laser sources 7, in order to couple the laser radiation with minimal loss.
[0071] In the embodiment shown in Fig. 3, the laser sources 7 and the mirror devices 1 assigned to each of the individual laser sources 7 are arranged completely outside the reactor chamber 6, i.e. both the FSM 2 and the deflecting mirror 9 are located outside the reactor chamber 6, so that the beam deflection takes place outside the vacuum of the reactor chamber 6.
[0072] Fig. 4 shows a schematic representation of an arrangement for exciting a laser-based fusion reaction according to a further embodiment of the present invention. In contrast to the previous embodiment according to Fig. 3, here the beam deflection takes place in the vacuum of the reactor chamber 6, which further improves the precision of the beam guidance. For this purpose, the FSMs 2 of the respective mirror assemblies 1 are arranged partially or even completely within the reactor chamber 6. The laser beams generated by the laser sources 7 arranged outside the reactor chamber 6 are directed into the reactor chamber 6 via coupling means 17 integrated into the reactor wall (e.g., in the form of optical fibers).
[0073] Specifically, Fig. 4 shows an advantageous embodiment in which the FSM 2 is only partially located in the vacuum of the reactor chamber 6. The individual components of the FSM 2 are advantageously divided such that sensitive parts of the FSM 2, such as electronic components (sensors, actuators, electronics), are arranged outside the reactor chamber 6 (and thus outside the vacuum). Only mechanical components of the FSM 2 (mirrors, solid-state hinge, and optionally passive parts of the magnetic circuit, such as permanent magnets) are located inside the reactor chamber 6. A vacuum barrier is formed inside the FSM 2, which ensures that the vacuum within the reactor chamber 6 is maintained and that no ambient air can pass through the FSM 2 into the reactor chamber 6. The vacuum barrier can be, for example,be designed in such a way that a hermetically sealed coupling point is formed between the (passive) components of the FSM 2 in the vacuum of the reactor chamber 6 and the (active) components outside the vacuum of the reactor chamber 6.
[0074] In the embodiment shown in Fig. 4, the mirror assembly 1 assigned to each individual laser source 7 comprises a mirror element 2 (FES) located on the side of the reactor chamber 6 opposite the coupling means 17 of the laser beam of the respective laser source 7. The beam path is configured such that a laser beam from a laser source 7 is directed onto the tilting mirror 3 of the FSE of the respective mirror assembly 1 on the opposite side of the reactor chamber 6. This allows for an alternating arrangement of laser sources 7 (or of inlet windows 10 for coupling the laser beams) and FSEs 2, thus maximizing the use of the available space in the reactor wall of the reactor chamber 6. A further advantage of this arrangement is that, after the laser beam is deflected by the FSE, no further optical elements are present in the beam path.This simplifies the design and calculation of the optical path of the laser beams towards Fusion Target 5.
[0075] In the examples according to Figs. 3 and 4, the fusion targets 5 can be sequentially injected into the reactor chamber 6 during operation, and the processes described above, i.e., the measurements on the fusion target 5, the alignment of the (imaginary) laser beams of the laser sources 7, and the simultaneous activation of the laser sources 7 to initiate or ignite the fusion reaction, can be carried out repeatedly, with a corresponding individual adjustment of the irradiation parameters (such as direction of the laser beams, time, duration, and energy content of each laser pulse, etc.) being made for each of the fusion targets 5 based on the respective measurements.Because many ignitions occur in succession, it is possible to employ machine learning (ML) methods and allow the process to continuously optimize itself with a superimposed self-learning artificial intelligence, whereby the information recorded by the measuring system 19 could be used as training data for the artificial intelligence. One possible target optimization parameter is the resulting reactor heat output. Alternatively or additionally, other parameters can also be defined as target optimization parameters, such as the resulting particle flux, i.e., neutrons in the case of a DT reaction (. 2 D + 3 T -> 4 He + n) or helium in the case of a pB reaction (p + 11 B -> 3 4 He), or the resulting scattered light.
[0076] In addition to the parameters obtained by the measuring system 19, according to an advantageous further development of the invention, further data, e.g. from temperature sensors distributed in the reactor wall, can be used to take into account the potential influence of the radiant heat from the reactor wall on the geometry and trajectory of the fuel.
[0077] Fig. 5 shows an embodiment of an arrangement for exciting a laser-based fusion reaction with a plurality of laser sources 7 and each associated mirror assembly 1. The specific setup is comparable for all laser sources 7 of the arrangement and is shown enlarged in Fig. 6 using the example of one laser source 7. A laser beam emitted from the laser source 7 first strikes a deflecting mirror 9 and from there a tilting mirror 3, adjustable in two spatial directions and designed as an FSM 2. With the aid of the tilting mirror 3, the laser beam can be directed through an entrance window 10 of the (not shown) reactor chamber onto a fusion target in the reactor chamber. In the example shown in Fig.In the example shown in Figure 5, the arrangement comprises a total of 256 laser sources 7, which are arranged spherically in the space around the reactor chamber in a uniform distribution, so that a fusion target in the reactor chamber can be irradiated uniformly and simultaneously with laser beams from many directions.
[0078] Fig. 7 shows a schematic representation of a fusion target 5, depicted as an ideal fuel sphere, and the target points of the laser beams on the surface of the fusion target 5. This representation corresponds to the irradiation setup according to Fig. 4 with a total of 256 laser sources, so that the surface of the fusion target 5 accordingly has 256 target positions, which are represented by the points in Fig. 7. According to the uniform distribution of the laser sources described in connection with Fig. 4, the 256 points are uniformly distributed on the surface of the fusion target 5.
[0079] In the illustrated embodiment, the number of target points and the beam diameter on the fusion target 5 are selected such that the energy of the lasers is distributed as evenly as possible over the fuel during simultaneous bombardment. Only in this way can a uniform implosion of the fuel be ensured and the Rayleigh-Taylor instabilities that may arise (comparable to the problem of compressing a balloon so evenly that no bulges occur) be suppressed as effectively as possible.
[0080] In the embodiment shown in Fig. 7, the fusion target 5 is a fuel sphere with a diameter of 1 mm. As already mentioned, the target points of the 256 laser beams (according to the geometric optics) are represented as points on the sphere's surface. Since the laser beams ideally have a Gaussian beam profile, the area irradiated by each laser beam is circular, with the diameter of the irradiated circular area being 125 pm in the illustrated embodiment. The circle shown for a target point of the laser beams indicates the extent of the beam profile on the target surface at which the laser intensity in the Gaussian profile has dropped to 1 / e of the maximum intensity at the center of the beam profile. With the given dimensions (1 mm diameter of the fusion target 5, 256 laser beams with a Gaussian profile), uniform coverage of the target surface can thus be achieved.The laser intensity is largely uniformly distributed across the surface, resulting in efficient compression and heating of the fusion target 5.
[0081] The fusion target 5 in the example shown in Fig. 7 is ideally spherical. However, if the shape of the target 5 deviates from the ideal spherical shape due to the manufacturing process or influences during injection into the reactor chamber 6, the spacing of the target points may need to be adjusted to take the surface shape into account and achieve uniform compression of the target 5. For example, in the area of a raised area or bulge, the spacing of the target points on the surface must be reduced to achieve the power density necessary for compression due to the accumulation of fuel at this point.
[0082] As already mentioned in connection with Fig. 4, the mirror devices 1 assigned to the individual laser sources 7 can be arranged partially or even completely within the reactor chamber 6. Fig. 8 shows in detail an embodiment according to such an arrangement with an FSM 2 as a component of a mirror device 1 and with a vacuum barrier. The FSM 2 comprises, in a manner known per se, a tilting mirror 3 and a sensor and actuator unit 4 for adjusting the tilting mirror 3 in two spatial directions. The sensor and actuator unit 4 comprises a sensor element 11 with a number of displacement sensors 13. Specifically, the sensor element 11 generally comprises two x-displacement sensors 13 arranged symmetrically to a mirror holder 12 in a first direction (x-direction) and two y-displacement sensors arranged symmetrically to the mirror holder 12 in a second direction orthogonal to the first direction (y-direction). These displacement sensors 13 detect the position orDeflection of a permanent magnet 14 that is firmly connected to or integrated into the mirror holder 12.
[0083] Behind the sensor element 11 is an actuator 15, which can act on the permanent magnet 14. Depending on the position signals from the displacement sensors 13 and depending on the desired target direction, the actuator 15 deflects the permanent magnet 14, thereby aligning the mirror holder 12 and thus the mirror 3 so that the laser beam is deflected in the desired direction.
[0084] In the embodiment shown in Fig. 8, the FSM 2 is designed with a vacuum barrier that allows the FSM 2 to be integrated into the reactor wall 16 of the reactor chamber 6. The vacuum barrier is designed such that certain "non-critical" components of the FSM 2 are arranged within the reactor chamber 6. These include, in particular, the mirror 3, the mirror holder 12 with the solid-state joint 18, via which the mirror holder 12 is connected to the reactor wall 16, and the permanent magnet 14. Outside the reactor chamber 6 and embedded in the reactor wall 16 are the sensor element 11 with the displacement sensors 13 and the actuator 15.
[0085] As already mentioned, the arrangement for exciting a laser-based fusion reaction according to the present disclosure comprises a measuring system for determining certain parameters of the fusion target, in particular, for example, its position and velocity within the reactor chamber, wherein the measuring system may include several cameras, each of which may have an FSM for image stabilization. In this case, the respective FSMs may be integrated into the reactor wall via a vacuum barrier in the same manner as previously described in connection with Fig. 8 for the FSMs of the mirror devices 1 associated with the laser sources 7.
[0086] Fig. 9 shows – in contrast to Fig. 7 – a deformed fusion target 5, which has an approximate ellipsoidal shape. To ensure uniform energy input of the laser beams onto the fusion target 5 and uniform compression, the specific shape of the surface of the fusion target 5 is determined by the measuring system 19. The control unit is configured to receive corresponding measurement data regarding the shape of the surface of the fusion target 5 from the measuring system 19 and, based on this measurement data, to adjust the tracking or setting of the tilting mirrors 3 of the mirror devices 1 for uniform irradiation of the fusion target 5 by the majority of laser beams. Specifically, the laser beams are aligned such that the target points of the laser beams are closer together at areas of higher material concentration. This is illustrated by way of example at one of the poles of the ellipsoid in Fig. 9.The distance between adjacent laser beams is di. In areas of lower material accumulation, however, the target points are set at a greater distance. This is illustrated in Fig. 9 at the equator of the ellipsoid, where the distance between adjacent laser beams is d2, with d2 > di. This ensures that the compression of the target is uniform, thus preventing the breakout of target material (and the associated Raleigh-Taylor instability).
[0087] Regarding further advantageous embodiments of the device according to the invention, reference is made to the general part of the description and to the attached claims to avoid repetition.
[0088] Finally, it should be expressly noted that the exemplary embodiments of the device according to the invention described above serve only to illustrate the claimed teaching and do not limit it to these exemplary embodiments. Reference numerals list
[0089] 1 Mirror assembly
[0090] 2 Fast Steering Mirror, FSM
[0091] 3 tilting mirrors
[0092] 4 sensor and actuator unit
[0093] 5 Fusion Target
[0094] 6 Reactor chamber
[0095] 7 Laser source
[0096] 8 Admission
[0097] 9 deflecting mirrors
[0098] 10 entry windows
[0099] 11 Sensor element
[0100] 12 Mirror bracket
[0101] 13 Position sensor
[0102] 14 permanent magnet
[0103] 15 Actuator
[0104] 16 Reactor wall
[0105] 17 coupling means
[0106] 18 Solid body joint
[0107] 19 Measuring system
[0108] 20 cameras
Claims
Claims 1. Arrangement for exciting a laser-based fusion reaction, comprising: a reactor chamber (6) with an inlet (8) for injecting fusion targets (5), a device for generating a plurality of laser beams for direct bombardment of the fusion target (5), wherein the direction of the laser beams is adjustable by means of a mirror device (1) with at least one tilting mirror (3) adjustable in at least one spatial direction, a measuring system (19) that is set up to record measurement data of the fusion target (5) inside the reactor chamber (6), and a control device which is set up to receive measurement data of the fusion target (5) from the measuring system (19) and, depending on the received measurement data, to adjust or adapt the tilting mirrors (3) of the mirror devices (1) in a manner individually adapted to the respective fusion target (5).
2. Arrangement according to claim 1, characterized in that the measurement data acquired by the measuring system (19) comprise position data and / or velocity data of the fusion target (5).
3. Arrangement according to claim 1 or 2, characterized in that the at least one tilting mirror (3) of the mirror device (1) is adjustable in two spatial directions.
4. Arrangement according to any one of claims 1 to 3, characterized in that the measuring system (19) is further configured to determine the shape of the surface of the fusion target (5), wherein the control device is configured to receive measurement data regarding the shape of the surface of the fusion target (5) from the measuring system (19) and, based on this measurement data, to adjust the tracking or adjustment of the tilting mirrors (3) of the mirror devices (1) for uniform irradiation of the fusion target (5) by the plurality of laser beams.
5. Arrangement according to any one of claims 1 to 4, characterized in that the measuring system (19) is further configured to determine a rotational speed and rotational direction of the fusion target (5).
6. Arrangement according to one of claims 1 to 5, characterized in that the measuring system (19) is designed as an optical measuring system (19) with a plurality of optical sensors.
7. Arrangement according to claim 6, characterized in that the optical sensors had a device for image stabilization, preferably in the form of an FSM.
8. Arrangement according to one of claims 1 to 7, characterized in that the measuring system (19) comprises a plurality of temperature sensors distributed on the inside of the reactor wall.
9. Arrangement according to one of claims 1 to 8, characterized in that the tilting mirrors (3) of the mirror devices (1) are designed as FSM (2).
10. Arrangement according to claim 9, characterized in that the FSM (2) comprises means for dissipating heat from the tilting mirror (3).
11. Arrangement according to claim 9 or 10, characterized in that the FSM (2) is integrated into the reactor wall (16) of the reactor chamber (6) forming a vacuum barrier, wherein the tilting mirror (3) and the mirror suspension (12) are located inside the reactor chamber (6) and the sensors (13) and actuators (15) for aligning the tilting mirror (3) are located outside the reactor chamber (6).
12. Arrangement according to any one of claims 1 to 10, characterized in that the tilting mirrors (3) of the mirror devices (1) are arranged outside the reactor chamber (6) and the laser beams can be directed into the reactor chamber (6) via feedthroughs formed in the reactor wall (16).
13. Arrangement according to any one of claims 1 to 12, characterized in that the spot diameter and the number of laser beams are dimensioned such that the superpositions of the individual distribution functions of the individual laser beams result in a uniform power density on the surface of the fusion target (5).
14. Method for exciting a laser-based fusion reaction, in particular for carrying out with an arrangement according to any one of claims 1 to 13, comprising: Injecting a fusion target (5) into a reactor chamber (6); Providing a device for generating a plurality of laser beams for direct bombardment of the fusion target (5), wherein the direction of the laser beams is adjusted by means of a mirror device (1) with at least one tilting mirror (3) adjustable in at least one spatial direction; Acquisition of measurement data of the fusion target (5) within the reactor chamber (6) using a measurement system (19); and Tracking or adjusting the tilting mirrors (3) of the mirror devices (1) in a manner individually adapted to the respective fusion target (5) depending on the measurement data of the fusion target (5) acquired by the measuring system (19).
15. Method according to claim 14, characterized in that the laser beams are generated by a plurality of individual laser sources (7), wherein the individual laser sources (7) are synchronized together.
16. A method according to claim 14 or 15, characterized in that compression of the fusion target (5) is triggered by means of a pre-irradiation comprising at least one generation of the plurality of laser beams, and ignition of the fuel in the compressed fusion target (5) is triggered by means of a subsequent irradiation comprising at least one generation of the plurality of laser beams.
17. A method according to any one of claims 14 to 16, characterized by the following steps: Measuring the fusion energy yield produced during the fusion reaction; and Optimizing the tracking or adjustment of the tilting mirrors (3) of the mirror devices (1) in a self-learning feedback loop using the measured fusion energy yield as a target optimization parameter.