- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Laser-induced acceleration of Helium ions from unpolarized gas jets
摘要： In order to develop a laser-driven spin-polarized 3He-ion beam source available for nuclear-physics experiments as well as for the investigation of polarized nuclear fusion, several challenges have to be overcome. Apart from the provision of a properly polarized 3He gas-jet target, one of the biggest milestones is the demonstration of the general feasibility of laser-induced ion acceleration out of gas-jet targets. Of particular importance is the knowledge about the main ion-emission angles as well as the achievable ion-energy spectra (dependent on the optimal set of laser and target parameters). We report on the results of such a feasibility study performed at PHELIX, GSI Darmstadt. Both 3He- and 4He-gas jets (ngas ～ 1019 cm?3) were illuminated with high-intensity laser pulses, ). The main ion-emission angles could be identi?ed (±90° with respect to the laser-propagation direction) and the ion-energy spectra for all ion species could be extracted: for the ions were 4.65 MeV (with a optimal laser and target parameters, the high-energy cut-offs for He + + 2 ,1 ), respectively. ) and 3.27 MeV (D normalized energy uncertainty of D ( 10 W cm =-? ? 1 =-? ? 1 0.055 0.033 ? ~ 19
关键词： laser-driven He-ion acceleration,spin-polarized ion source,polarized nuclear fusion
更新于2025-09-23 15:19:57
-
Surface Morphological Features of Molybdenum Irradiated by a Single Laser Pulse
摘要： Molybdenum (Mo) is considered a plasma facing material alternative to tungsten (W) for manufacturing the divertor armours of International Thermonuclear Experimental Reactor (ITER). Transient thermal loads of high energy occurring in a tokamak during the service life have been simulated through a single laser pulse delivered by a Nd:YAG/Glass laser, and the effects have then been examined through scanning electron microscopy (SEM) observations. An erosion crater forms in correspondence with the laser spot due to the vaporization and melting of the metal, while all around a network of cracks induced by thermal stresses is observed. The findings have been compared to results of similar experiments on W and literature data. The morphology of the crater and the surrounding area is different from that of W: the crater is larger and shallower in the case of Mo, while its walls are characterized by long filaments, not observed in W, because the lower viscosity and surface tension of Mo allow an easier flow of the liquid metal. Most importantly, the volume of Mo ablated from the surface by the single laser pulse is about ten times that of W. This critical aspect is of particular relevance and leads us to conclude that W remains the best solution for manufacturing the armours of the ITER divertor.
关键词： laser,nuclear fusion reactors,surface damage,molybdenum,microstructure
更新于2025-09-19 17:13:59
-
A high power laser facility to conduct annealing tests at high temperature
摘要： The knowledge of material properties and their behavior at high temperatures is of crucial importance in many fields. For instance, annealing phenomena occurring during the thermomechanical processing of materials, such as recrystallization, have long been recognized as being both of scientific interest and technological importance. Different methods are currently used to study annealing phenomena and submit metals to heat loads. In this work, we present the design and the development of a laser-based facility for annealing tests. This experimental setup enables studies at the laboratory scale with great flexibility to submit samples to various spatial and temporal heating profiles. Due to the possibility of having optical access to the sample, laser heating can be combined with several non-contact diagnostics such as infrared imaging to control and analyze the temperature gradients. As a case study, we present a set of experiments performed to study the recrystallization kinetics of tungsten. We demonstrate that samples can be heated linearly with heating rate up to ～2000 K/s, at temperatures above 2000 K, for seconds or hours, with typical errors in the temperature measurement of around 1% that depend mainly on the determination of sample emissivity. Such studies are of crucial interest in the framework of nuclear fusion since the international thermonuclear experimental reactor nuclear reactor will operate with a full-W divertor.
关键词： tungsten,laser annealing,nuclear fusion,high temperature,recrystallization
更新于2025-09-19 17:13:59
-
Recent Developments in Dual-Laser Digital Holography for Plasma-Facing Surface Characterization
摘要： A digital holography device is currently undergoing development at the Oak Ridge National Laboratory for the purpose of measuring surface topography, with the goal of deployment as a real-time plasma-facing component diagnostic for the study of materials that could be utilized in a nuclear fusion device. The holography system utilizes one or two lasers depending on the scale of surface features under measurement. Measurements of surface roughness were performed in a single-laser mode and compared with the data from profilometry, with a linear correlation of increased holographic measurement fidelity as surfaces became smoother. Characterization of the dual-laser operating mode has been performed via surface measurement of stainless steel targets with “stair-step” features in various sizes. Results demonstrated that surface features with known sizes as small as 25.4 μm could be resolved. Measurements were within ～55 μm or less deviation from the actual sizes, and measurement accuracy was improved as feature size was increased, corresponding to the effect of noise becoming less pronounced. A target exposed to plasma generated by an electrothermal (ET) arc source was analyzed with flat-field correction and averaging of sequential image frames to demonstrate the improved measurement quality in preparation for future use of holography on ET arc-exposed targets.
关键词： plasma-facing component interaction (PMI),Digital holography (DH),plasma (PFC),plasma-material diagnostic,nuclear fusion
更新于2025-09-12 10:27:22
-
Lightning-Rod Effect of Plasmonic Field Enhancement on Hydrogen-Absorbing Transition Metals
摘要： The plasmonic enhancement of electromagnetic ?eld energy density at the sharp tips of nanoparticles or nanoscale surface roughnesses of hydrogen-absorbing transition metals, Pd, Ti, and Ni, is quantitatively investigated. A large degree of energy focusing is observed for these transition metals in the microwave region, even surpassing the enhancement for noble metals according to the conditions. Pd, for instance, exhibits peak ?eld enhancement factors of 6000 and 2 × 108 in air for morphological aspect ratios of 10 and 100, respectively. Metal surfaces possibly contain such degrees of nano- or micro-scale native random roughnesses, and, therefore, the ?eld enhancement e?ect may have been unknowingly produced in existing electrical and optical systems. In addition, for future devices under development, particularly in hydrogen-related applications, it is desirable to design and optimize the systems, including the choice of materials, structures, and operating conditions, by accounting for the plasmonic local energy enhancement e?ect around the metal surfaces.
关键词： nuclear fusion,sensing,transition metal,surface plasmon,nanophotonics,energy device,hydrogen storage,nanoparticle
更新于2025-09-12 10:27:22