Laser two-color scattering (TCS) is proposed to detect the neutral species in the edge of fusion devices, namely, tokamaks. TCS uses two wavelengths to probe both the laser Rayleigh scattering and Thomson scattering of the neutral-electron bath, with emphasis on neutral density measurements such as that of hydrogen and deuterium. Modeling of the Rayleigh scattering of tokamak neutral species under various plasma conditions (electron density and temperature) shows that, with an appropriate filtering of the Thomson signal and by going to ultraviolet-region wavelengths, identification of the Rayleigh signal can be achieved. Photon count and signal fractions are calculated in two test cases, one in the midplane region of the National Spherical Torus Experiment and one in the divertor region of DIII-D. An uncertainty analysis and discussion of the feasibility of the TCS diagnostic is also presented.
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http://dx.doi.org/10.1063/5.0027481 | DOI Listing |
Proc Natl Acad Sci U S A
December 2024
Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen 37077, Germany.
Optical imaging access to nanometer-level protein distributions in intact tissue is a highly sought-after goal, as it would provide visualization in physiologically relevant contexts. Under the unfavorable signal-to-background conditions of increased absorption and scattering of the excitation and fluorescence light in the complex tissue sample, superresolution fluorescence microscopy methods are severely challenged in attaining precise localization of molecules. We reasoned that the typical use of a confocal detection pinhole in MINFLUX nanoscopy, suppressing background and providing optical sectioning, should facilitate the detection and resolution of single fluorophores even amid scattering and optically challenging tissue environments.
View Article and Find Full Text PDFJ Phys Chem B
September 2024
Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London SW7 2AZ, United Kingdom.
Free electron lasers operating in the soft and hard X-ray regime provide capabilities for ultrafast science in many areas, including X-ray spectroscopy, diffractive imaging, solution and material scattering, and X-ray crystallography. Ultrafast time-resolved applications in the picosecond, femtosecond, and attosecond regimes are often possible using single-shot experimental configurations. Aside from X-ray pump and X-ray probe measurements, all other types of ultrafast experiments require the synchronized operation of pulsed laser excitation for resonant or nonresonant pumping.
View Article and Find Full Text PDFPhys Rev E
June 2024
Faculty of Physics, Weizmann Institute of Science, Rehovot 7610001, Israel.
We report on experimental and theoretical studies on the Stark profile of the He ii Paschen-α line over a wide range of plasma parameters. This line was emitted from a laser-induced plasma with electron densities in the range of 8.1×10^{22}-4.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
October 2024
Department of Chemical Engineering, Northeastern University, Boston, MA, USA.
Multiplexed fluorescence in vivo imaging remains challenging due to the attenuation and scattering of visible and traditional near infrared (NIR-I, 650-950 nm) wavelengths. Fluorescence imaging using shortwave infrared (SWIR, 1000-1700 nm, a.k.
View Article and Find Full Text PDFNanoscale
June 2024
Department of Chemistry and The Photonics Center, Boston University, Boston, MA 02459, USA.
Plasmonic molecules are discrete assemblies of noble metal nanoparticles (NPs) that are of interest as transducers in optical nanosensors. So far, NPs with diameters of ∼40 nm have been the preferred building blocks for plasmonic molecules intended as optical single molecule sensors due to difficulties associated with detecting smaller NPs through elastic scattering in conventional darkfield microscopy. Here, we apply 405 nm, 445 nm two-color interferometric scattering (iSCAT) microscopy to characterize polyethylene glycol (PEG) tethered dimers of 10 nm and 20 nm Ag NPs and their monomers.
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