The BMBF-funded IFE Targetry HUB project was launched at the end of 2024 with the aim of researching basic target fabrication and fielding technologies for laser-based inertial confinement fusion in Germany.
Nuclear fusion has enormous potential to solve energy demand problems worldwide. Laser-driven inertial fusion is the only scheme that has demonstrated scientific net energy gain, yet the engineering challenge remains to implement reliable fusion technology and build a commercially viable fusion power plant.
The German joint project, consisting of 15 partners from research and industry under the leadership of Fraunhofer Institute for Applied Solid State Physics (IAF) and Focused Energy GmbH, has started research on so-called targets. This key component of laser-based inertial confinement fusion comprises the hydrogen fusion fuel and the ablator material needed to compress and fuse the hydrogen isotopes deuterium and tritium.
The promise of nuclear fusion: A global energy solution
Following the first successful demonstration of deuterium and tritium fusion and burn with net positive scientific gain at Lawrence Livermore National Laboratory, interest in fusion technology has grown rapidly around the world. However, there is still a long way to go before nuclear fusion can be used commercially as a sustainable energy source that will offer great value to society. The BMBF-funded project “Inertial Fusion Energy (IFE) Targetry HUB for DT Inertial Fusion” (IFE Targetry HUB) is now laying an important foundation for research into laser-based inertial fusion in Germany.
Any form of laser-driven inertial confinement fusion is a pulsed process in which a target filled with the hydrogen isotopes deuterium and tritium is compressed and ignited using many high-energy laser beams as drivers. A temperature of up to 120 million degrees Celsius is reached, vaporising the target and simultaneously heating and compressing the fuel to multiple times solid density. This enables the fusion reaction in which the positively charged atomic nuclei overcome their mutual repulsion and fuse to form helium while releasing enormous amounts of energy.
Research and development are still necessary to improve the properties of existing targets in order to ensure the necessary qualitative progress for the development of a power plant, e.g., in terms of yield and reproducibility. Current targets are extensively measured and characterised so that the results of a fusion experiment can be compared with simulations.
The fundamental ability to produce targets with suitable properties for fusion is of crucial relevance for the realisation of a fusion power plant. The costs per target with a repetition rate of >10⁶ shots per day must be significantly reduced for a commercially viable power plant. For the targets that were successfully tested at LLNL and created by a partner of this consortium, Diamond Materials, individual production is state-of-the-art.
The IFE Targetry HUB Initiative
The IFE Targetry HUB project aims to develop concepts that, on the one hand, improve the fusion properties and make progress verifiable, but at the same time, can be manufactured in ever larger quantities.
The supply of material for the injection and fixation of the fusion fuel is of paramount importance for the power plant. As previous fusion experiments have shown, the quality of the compressed targets is a key skill for IFE, which determines essential success factors. The fusion target must meet the immense qualitative requirements (material, geometric, thermal, mechanical parameters) and retain its characteristics while being accelerated and injected at high speed into the reactor chamber, as well as being produced in sufficient quantities, characterised and examined with regard to reproducibility.
The creation of a material and process basis, as well as a characterisation basis, is the prerequisite for this undertaking. Essential available and foreseeable technologies are combined in this project so that both production and suitable and innovative characterisation methods are developed. With regard to the manufacturing methods, the final goal must be to improve the material quality so that 100% control can be permanently avoided using statistical controls.
In the IFE Targetry HUB, the partners contribute their different expertise covering basic research, applied research and industry to jointly research suitable materials and processes for the functional and cost-efficient scalable production and characterisation of Hydrogen fuel targets for laser-based inertial confinement fusion. These targets represent a bottleneck for efficient nuclear fusion and are, therefore, a key technology on the way to the laser-based fusion power plant of the future.
Previous demonstrations have used spherical diamond targets as small as 1mm in diameter. Target geometry, interface properties and purity, as well as material quality, are critical to the success of nuclear fusion. The IFE Targetry HUB is now developing and implementing high-precision manufacturing processes, such as additive manufacturing of foams or plasma coating and characterisation of target components. The aim of the research is scalable target production that meets the high requirements for successful laser-based inertial confinement fusion.
Advancements in target production for laser-based inertial fusion
The aim of the IFE Targetry HUB joint project is to form a material, process and characterisation basis for the simultaneous production of functional and cost-efficient targets for laser-based inertial fusion. Based on the development of new high-density carbon (HDC) diamond targets, HDC targets with novel silicon doping are similar to the previous tungsten-based HDC targets. In the derivation of the findings from HDC development, the aim is to research manufacturing processes that allow the simultaneous production of targets in an initial number of at least 5,000 pieces. So far, the available HDC fabrication techniques are amenable to yield only small quantities of up to a few tenths of high-quality targets.
The development towards a high number of target production is evidence-based, based on the analysis of the achieved material quality through fusion testing (firing). On the basis of the existing experimental results, criteria for material evaluation with regard to repeated fusion are being developed. For this purpose, both a simulation and a characterisation basis are being established.
Furthermore, additive manufacturing processes for polymer targets are being developed and investigated in order to produce foams and, in combination with atmospheric pressure plasma technology, modify them and embed them in process flows with low contamination. This could potentially, after proof of suitability for fusion, enable very high production rates at low process costs.
The already well-established 2PP printing technology with point-point interaction is being improved in terms of the achievable resolution and, in parallel, a new type of 2PP projection lithography is being developed, which significantly reduces the printing time of IFE targets. New statistical characterisation methods using microwave resonators and X-ray tomography are to be developed to capture a large number of targets using static characterisation methods.
The possibility is created to measure essential parameters of those materials at cryogenic temperatures that are to be used in the IFE target. In addition, a test stand will be implemented to test the behaviour of IFE foams and integrated foam and ablation spherical shell targets, which can be examined when filled with liquid hydrogen via a microcapillary.
Microcomponents must be characterised before they can be used as IFE targets in laser-plasma experiments or in the first fusion test reactor. The requirements regarding material purity, concentricity and sphericity of the ablation spherical shell, homogeneity of the foam filled with DT ice, as well as, for example, the position of the cone in the spherical shell for the Proton Fast Ignition, are just a few quality parameters that must be determined with the highest precision. For this purpose, specific measuring devices will be developed and qualified as part of this research project.
After the successful demonstration of a functional target production process in medium quantities under laboratory conditions, the results will be incorporated into the progressive development of the production process necessary to produce a sufficiently large number of targets for commercial reactor operation.
The company Focused Energy GmbH, along with the other industrial partners, will transfer the positive results of this three-year research funding into the subsequent development phase and bring together and validate the processes and products developed specifically for IFE target production by the respective project partners.
The IFE Targetry HUB is funded by the Federal Ministry of Education and Research BMBF. Fraunhofer IAF and Focused Energy GmbH coordinate the project consortium, consisting of:
- Focused Energy GmbH
- Karlsruhe Institute of Technology—Tritium Laboratory Karlsruhe (KIT-TLK)
- Technical University of Darmstadt with
- Institute for Nuclear Physics (IKP)
- Institute for Nano- and Microfluidics (NMF)
- Institute for Production Engineering and Forming Machines (PtU)
- KERN Microtechnik
- Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V. with
- Fraunhofer Institute for Applied Solid State Physics IAF (coordinator)
- Fraunhofer Institute for Laser Technology ILT
- Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM
- Fraunhofer Institute for Integrated Circuits IIS—Development Center X-ray Technology EZRT
- Diamond Materials
- Plasmatreat GmbH
- LightFab GmbH
- ModuleWorks GmbH
- Herkula Farben GmbH
The work was funded by the German federal ministry of education and research, BMBF, in the initiative IFE Targetry HUB, FKZ: 13F1013A.
The support of the VDI technology centre, Dr. Thomas Kuschel, is greatly acknowledged.
Please note, this article will also appear in the 21st edition of our quarterly publication.
