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The infrared imaging video bolometer at Wendelstein 7-X
No full textThe radiated power distribution is a crucial aspect of heat transport, heat load mitigation, and plasma exhaust performance. An imaging video bolometer camera has been installed to measure the plasma radiated power in the divertor region of the Wendelstein 7-X (W7-X) stellarator. This diagnostic offers a wide-angle (40° × 68°) sampling of the plasma volume in both the poloidal and toroidal directions. The field-of-view is covered with a large number (>500) of bolometer channels, providing imaging capability. The diagnostic design is introduced here together with its data analysis procedure. A set of laboratory experiments is performed to assess the thermal properties of the gold absorber foil and their spatial uniformity. Following installation, a heat source originating from the inertially cooled front of the diagnostic is identified and filtered out. The discharge data indicate a satisfactory signal-to-noise ratio as well as spatiotemporal resolution. These represent the first toroidally resolved images of the line-integrated radiated power in the W7-X island divertor. The diagnostic was then upgraded with a thinner platinum absorber and adjusted mirrors. Early data from the most recent experimental campaign employing the upgraded design show a considerable improvement in the diagnostic performance with more bolometer channels (>1400) , extended coverage, and increased spatial resolution
Approach of a digital twin for the high-frequency dynamics (FMR) of arbitarily shaped, symmetric ferromagnetic polycrystalline samples
No full textUnderstanding the Component-Driven Influence on the Electrochemical Properties in Single-Ion Polymer Electrolytes for Sodium-Based Batteries
No full textState-of-the-Art of High-Power Gyro-Devices: 2025 Update of Experimental Results
No full textThis report presents an update of the experimental achievements published in the review “State-of-the-Art of High-Power Gyro-Devices and Free Electron Masers,” Journal of Infrared, Millimeter, and Terahertz Waves, 41, No. 1, pp 1–140 (2020) related to the development of gyro-devices (Tables 2–34). Emphasis is on high-power gyrotron oscillators for long-pulse or continuous wave (CW) operation and pulsed gyrotrons for many other applications. In addition, this work gives a short update on the present development status of frequency step-tunable and multi-fre-quency gyrotrons; coaxial-cavity multi-megawatt gyrotrons; complex two-section stepped cavity gyrotrons; gyrotrons for technological and spectroscopy applica-tions; relativistic gyrotrons; large orbit gyrotrons (LOGs); quasi-optical gyrotrons; fast- and slow-wave cyclotron autoresonance masers (CARMs); gyroklystron, gyro-TWT, and gyrotwystron amplifiers; gyro-harmonic converters; gyro-BWOs; and dielectric vacuum windows for such high-power mm-wave sources. Gyrotron oscil-lators (“gyromonotrons or just gyrotrons”) are mainly used as high-power millim-eter-wave sources for electron cyclotron heating (ECH), electron cyclotron current drive (ECCD), stability control, and diagnostics of magnetically confined plasmas for clean generation of energy by controlled thermonuclear fusion. Megawatt-class gyrotrons employ synthetic-diamond output windows and single-stage depressed collectors (SDCs) for electron energy recovery. The maximum pulse length of the 140 GHz, 1.3 MW IPP-KIT-THALES gyrotron is 3 min (1.2 MW/6 min) at 97.5% Gaussian output mode purity and 47% efficiency. The 1 MW version of this tube operates at pulse lengths up to 30 min, and PLL-frequency stabilization has been demonstrated. The first Japan QST-CANON 170 GHz ITER gyrotron prototype achieved 1 MW, 800 s at 55% efficiency and holds the energy world record of 2.88 GJ (0.8 MW, 60 min, 57%). The Russian 170 GHz ITER gyrotron obtained 0.99 (1.2) MW with a pulse duration of 1000 (100) s and 57 (53)% efficiency. First frequency-injection-locked operation of a very high-order-mode Russian 170 GHz-1 MW
gyrotron (IAP) has been demonstrated in short pulses using a PLL-frequency-sta-bilized 20 kW gyrotron master oscillator. A Russian short-pulse 74.2 GHz, 100 kW
gyrotron (SPbSTU) with 4-stage depressed collector achieved an efficiency of 72%.
The prototype tube of the KIT 2 MW, 170 GHz coaxial-cavity gyrotron (pulse dura-tion 50 ms) achieved in 1 ms pulses the record power of 2.2 MW at 48% efficiency
and 96% Gaussian mode purity and was operated at pulse lengths up to 50 ms. High-power CW gyrotron oscillators have also been successfully used in materials
processing. Such technological applications require tubes with the following param-eters: f ≥ 24 GHz, Pout = 4–50 kW, CW, η ≥ 30%. Gyrotrons with pulsed magnet for
various short-pulse applications deliver Pout = 210 kW with τ = 20 μs at frequencies up to 670 GHz (η ≅20%), Pout = 5.3 kW at 1 THz (η = 6.1%), and Pout = 0.5 kW at
1.3 THz (η = 0.6%). The average powers produced by 94 GHz gyroklystrons, gyrot-wystrons, and gyro-TWTs are 10 kW, 5 kW, and 20 kW, respectively
Pulsed-laser induced gold microparticle fragmentation by thermal strain
Full text linkLaser fragmentation of suspended microparticles (MP-LFL) is an upcoming alternative to laser ab-
lation in liquid (LAL) that allows to streamline the delivery processes and to optimize the irradiation
conditions for best efficiency. Yet, the structural basis of this process is not well understood to date.
Herein we employed ultrafast x-ray scattering upon picosecond laser excitation of a gold microparticle
suspension in order to understand the thermal kinetics as well as structure evolution after fragmen-
tation. The experiments are complemented by simulations according to the two-temperature model
to verify the spatiotemporal temperature distribution. It is found that above a fluence threshold of
750 J/m2 the microparticles are fragmented within a nanosecond into several large pieces where the
driving force is the strain due to a strongly inhomogeneous heat distribution on the one hand and
stress confinement due to ultrafast heating compared to stress propagation on the other hand. An
additional limited formation of small clusters is attributed to photothermal decomposition on the
front side of the microparticles at a fluence of 2700 J/m2
Non-targeted analysis of lipophilic and hydrophilic metabolites to distinguish between fresh and frozen-thawed fish of certain fish species using comprehensive 1H NMR spectroscopy and multivariate data analysis
Full text linkFood fraud along the production chain is a well-known issue that requires an effective authenticity control. For the differentiation of fresh and frozen-thawed fish, H nuclear magnetic resonance (NMR) spectroscopy based methods in combination with multivariate data analysis have proven to be suitable in principle. Here, from a total of 317 samples (cod, rainbow trout, mackerel; fresh and frozen-thawed), the lipid and polar fractions of the fish flesh were analyzed, and classification models based on a principal components analysis with linear discriminant analysis (PCA-LDA) including cross-validation were generated. Additionally, data fusions were carried out. The obtained average accuracies of > 90% (94.0% based on the lipid fraction, 92.8% based on the polar fraction) and > 95% (95.6% based on a low-level data fusion, 95.5% based on a mid-level data fusion) demonstrated a promising differentiation. Further examinations confirmed that the non-targeted analysis appears to be mandatory as no marker substances were indicated in the loadings plots of the models. To evaluate whether the generated classification models are suitable to be used in a broader manner, they were applied to 13 fresh and 13 frozen-thawed samples from twelve other common edible fish species in a preliminary study. The classification model based on the low-level data fusion gave the best results (84.6% of all 26 samples correctly predicted). Thus, although these models are very suitable for analyzing cod, rainbow trout, or mackerel for a classification as fresh or frozen-thawed, they cannot generally be applied to samples of other fish species
Self-Supervised Learning Strategies for a Platform to Test the Toxicity of New Chemicals and Materials
Full text linkHigh-throughput toxicity testing offers a fast and cost-effective way to test large amounts of compounds. A key component for such systems is the automated evaluation via machine learning models. In this paper, we address critical challenges in this domain and demonstrate how representations learned via self-supervised learning can effectively identify toxicant-induced changes. We provide a proof-of-concept that utilizes the publicly available EmbryoNet dataset, which contains ten zebrafish embryo phenotypes elicited by various chemical compounds targeting different processes in early embryonic development. Our analysis shows that the learned representations using self-supervised learning are suitable for effectively distinguishing between the modes-of-action of different compounds. Finally, we discuss the integration of machine learning models in a physical toxicity testing device in the context of the TOXBOX project
The impact of accelerator data on our understanding of extensive air showers
Full text linkBefore the start of CERN in 1954, cosmic rays (CR) were the main source of high energy particles leading to the discovery of anti-matter, muons and first mesons. Then particle accelerators provided controlled environments for studying high-energy particle interactions, producing precise data leading to the development of the Standard Model. These data were used early-on to create models to study extensive air showers (EAS), complex particle cascades initiated by high-energy cosmic rays, but its only in the late 90\u27s that both EAS models and experiments became precise enough to start to see discrepancies between hadronic model predictions and EAS data. Problems like "the muon puzzle", characterized by an unexpected surplus of muons in cosmic ray showers, has propelled further investigations into particle interactions. This talk will discuss how accelerator data have improved the accuracy of EAS models, resolved discrepancies, and offered new insights into hadronic interactions. We will also address the challenges and future directions in integrating accelerator data with EAS observations, underscoring the importance of taking into account all type of colliding system. From the simplest electron-positron annihilation to the most complex Lead-Lead or the newest proton-Oxygen interactions, we need them all to resolve the remaining inconsistencies in the models and finally improve the predictions for Astroparticle physics
